A gaming device which displays multiple results wherein subsequently displayed results are formed from previously displayed results. A gaming device randomly generates and displays a first set of symbols. The gaming device also generates a second set of symbols. The second set of symbols are not initially displayed to a player. The gaming device compares the first and second set of symbols to determine whether any symbols in the first set of symbols match any symbols in the second set of symbols. The gaming device displays the matching symbols and then displays the second set of symbols.

Gaming machines and specifically slot machines currently exist with mechanical or video reels having symbols thereon. In general, a player is awarded one or more credits in a slot gaming machine when one or more randomly generated symbols or combination of symbols appear on a payline. Known gaming devices also award credits for combinations of scattered symbols.
To increase player enjoyment and excitement provided by gaming machines, gaming device manufacturers constantly strive to provide players with new types of gaming machines that attract players and keep players entertained. One proven way manufacturers use to make their gaming machines more popular is to increase the number and variety of winning combinations and provide more opportunities for the player to win. Providing more variety and opportunities holds the player's interest for a longer time and also enables the manufacturer to have a wider range of payouts for the winning combinations.
To increase the number and variety of winning combinations, manufacturers have increased the number of paylines, the number of symbol positions or paystops and the number of gaming reels.
Paylines are generally predetermined arrays or reel stop positions of the set of reels where the gaming machine evaluates whether a predetermined combination of symbols occurred. A payline may consist of any number or configurations of positions of gaming symbols. For example, a payline for a set of reels can consist of a horizontal line of gaming symbols along the reels, or a diagonal line of gaming symbols along the reels, or a line overlapping several rows along the reels. It is well known to provide gaming machines with multiple paylines. With the increased complexity of the number and the positioning of the paylines on a singular set of reels, it becomes increasingly unwieldy for the gaming software to evaluate a winning combination or combinations of gaming symbols. At some point, adding variety yields diminished returns because of increased complexity. Multiple winning combinations may also become too complex for the player (i.e., a player may win after a given spin of the reels and find it difficult to determine how, where or why the player has won).
Gaming manufacturers have also increased the number of symbol positions or paystops. Increasing the number of paystops increases the number of different symbols a game can have and increases the number of times a particular symbol can appear. One way manufacturers have increased the number of paystops has been to increase the size of the reel to accommodate more stops. Original gaming machines had approximately ten stops per reel, modern mechanical reels have approximately thirty to thirty-five stops per reel and modern video machines have no technical physical limit. Increasing the number of times that a symbol can appear increases its likelihood of appearance, which affects the payout of a winning combination containing that symbol.
Another way manufacturers have increased the number of paystops has been to add reels. Many current slot machines display a set of five reels with three gaming symbols visible on each reel. This results in a visible set of gaming symbols in a three by five configuration. Slot machines may also utilize more than five reels and/or more than three visible gaming symbols on each reel, such as a ten reel configuration with ten visible gaming symbols on each reel. Such a slot machine may have a large number of potential paylines on a singular set of reels. As with increasing the paylines, the additional reels increases the complexity of the slot machine and eventually the slot machine becomes too unwieldy for the player and/or its software. For example, video reel machines have not increased the number of reels above five mainly because five reels created enough diversity to keep the game interesting without becoming too complex for the player to enjoy.
Current gaming machines also provide secondary or bonus games in addition to primary games. These secondary or bonus games are generally different from the primary game. The secondary or bonus games are generally played separately from the primary game. For instance, secondary or bonus games may be evaluated with a different set of predetermined combinations of the gaming symbols and/or different paylines. Bonus games may also be completely different games.
It should accordingly be appreciated that gaming machines have become rather complex in comparison to the original three reel, ten stop machine created before 1900. At some point, adding variety yields diminished returns as the inevitable accompanying complexity of placing multiple bets and trying to keep tract of multiple winning combinations for each bet becomes too complex for the player. A player may win after a given spin of the reels and find it difficult to determine how, where or why the player has won. Mechanical reels, which are limited in drum radius, have limited space with which to display the multitude of symbols. Simulated reel displays are also limited in size to make room for other input devices and displays requiring panel space. The limited display space and viewing area furthers the complexity created by the multitude of paylines and winning combinations.
Therefore, a need exists to create new and exciting games which increase the player's enjoyment and excitement. It is desirable to provide new gaming machines wherein a player has the opportunity to increase the number and variety of winning combinations and provide more opportunities for the player to win. It is also desirable to provide new gaming machines with new games whereby players can easily recognize winning combinations of gaming symbols, how those symbols were generated, and how and where the player won.

Gaming device which displays multiple gaming results wherein subsequent results are formed from previous results


The present disclosure relates to a method for the gear manufacturing machining of a workpiece in which a hobbing machining of the workpiece takes place to generate a gearing geometry of the workpiece, wherein the workpiece is gear manufacturing machined by gear skiving in addition to the hobbing machining.

Hobbing is a machining process for gear cutting using a defined blade. The hobbing tool typically has a plurality of blade teeth that are arranged on the periphery of the hobbing tool. A cutting movement by which a machining material removal takes place at the workpiece is achieved by rotating the hobbing tool.
Hobbing machining therefore permits a high material removal and is typically used for manufacturing a gearing at a toothed or non-toothed blank of the workpiece. A surface geometry of the hobbed workpiece suffering from relatively high tolerances results from the blade geometry and from the feed movement of the tool for manufacturing the gearing, in particular in rough machining. A hobbing machining furthermore requires good accessibility of the gearing since specific free spaces have to be available for the first cut path and the overrun of the tool.
Due to the high tolerances of the surface geometry created in the work piece by hobbying, hobbing is typically used as a soft machining for manufacturing a gearing and is combined after hardening with a hard-fine machining such as grinding or honing by which the desired surface quality is ensured. If only small overruns are available with the desired gearing, a shaping method that makes different demands on overruns than a hobbing process is typically used instead of the hobbing process.
Further methods for gear manufacturing machining are known in addition to hobbing machining. One of these methods is gear skiving. In this process, a tool having a defined blade hobs over the workpiece with a scraping movement and is led along the workpiece in the width direction. Gear skiving has long been known as a method, but has at best a subordinate significance due to the high tool wear. Gear skiving processes in combination with methods for reworking the gearing are known from DE 103 05 752 A1, DE 10 2015 120 556 A1 and DE 10 2015 104 242 A1. Gear skiving, in a similar manner to gear shaping, manages with considerably smaller first cut paths and overruns than are required for hobbing
The present disclosure comprises a method for the gear manufacturing machining of a workpiece in which a hobbing machining of the workpiece is used to generate a gearing geometry of the workpiece. The method in accordance with the disclosure is characterized in that the workpiece is additionally gear manufacturing machined by gear skiving in addition to the hobbing machining. Toothed workpieces can therefore be manufactured by the disclosed method. At least two machining steps are used for manufacturing the desired gearing geometry of the workpiece with the hobbing machining and the gear skiving.
The combined use of a hobbing machining and a gear skiving machining as disclosed herein allows the respective advantages of these processes to be combined with one another and/or to expand the workpiece geometries that can be at least partially manufactured by a hobbing machining.
The hobbing machining and the gear skiving take place by the same gear cutting machine. Costs and time in the manufacture of the toothed workpieces can hereby be saved.
Further, the hobbing machining and the gear skiving take place with the same fixing of the workpiece in a workpiece holder of the gear cutting machine. Since the workpiece remains in the workpiece holder for both machining steps, the cycle time required for the manufacturing is reduced.
Alternatively or additionally, a hobbing tool used for hobbing machining and a gear skiving tool used for gear skiving can be held in the same tool mount of the gear cutting machine and/or can be traveled through the axes of the same machining head of the gear cutting machine at least while carrying out the respective machining step. The construction effort and the costs for the gear cutting machine are hereby reduced.
In a first preferred variant, the hobbing tool and the gear skiving tool are fixed on the same tool arbor. The construction effort and the cycle time are hereby minimized since both machining steps can be carried out using only one tool holder without any tool change.
In a second variant, the gear cutting machine has two tool holders so that the hobbing tool and the gear skiving tool can be held in one tool holder each. A short cycle time is also hereby made possible since the necessity of a tool change is dispensed with. The two tool holders are arranged at a machining head and can therefore be traveled over the same travel axes of the gear cutting machine.
In a third variant, the gear cutting machine has an automatic tool changer for changing between the hobbing tool and the gear skiving tool. Only one tool holder is hereby required. Due to the increased cycle time, such a procedure rather presents itself for the manufacture of gearing arrangements with a longer machining time and smaller batch sizes.
In an embodiment, a feed movement of the respective tool in parallel with an axis of the workpiece holder takes place in the hobbing machining and/or in the gear skiving. This can in particular take place via a slide of the machining head of the gear cutting machine travelable in parallel with the axis of the workpiece holder.
In an embodiment, the rotary movement of the workpiece holder is coupled to the feed movement and/or to a rotary movement of the tool holder.
In an embodiment, the machining head of the gear cutting machine and in particular the tool holder in which the tool for hobbing machining and the tool for gear skiving are held and pivoted relative to the axis of the workpiece holder between the two machining steps. The different axial cross angles respectively required for the two machining steps can hereby be provided. The pivoting takes place about a pivot axis of the machining head extending perpendicular to the axis of the workpiece holder and/or tool holder.
The hobbing machining takes place at a first axial cross angle between the tool and the workpiece and the gear skiving machining takes place at a second axial cross angle between the tool and the workpiece, with the difference between the first and second axial cross angles amounting to more than 45°. Very different axial cross angles are hereby taken in account for the hobbing machining and for the gear skiving machining. The difference can in particular amount to more than 70°. The machining head is therefore pivoted about a corresponding pivot angle between the two machining steps.
Alternatively or additionally, the difference between the first and second axial cross angles can amount to less than 135°, less than 110°, further less than 100°.
Since such a pivot angle is not available on known hobbing machines, a gear cutting machine having a correspondingly large pivot region and specifically adapted to the carrying out of both a hobbing machining and a gear skiving machining is used.
The tool holder in which the tool for the hobbing machining and the tool for the gear skiving are held is shifted relative to the workpiece between the two machining steps. If both tools are fixed on the same arbor, the other tool can hereby be brought into engagement with the region of the workpiece to be machined.
The shifting takes place via a slide of the machining head supporting the workpiece holder travelable in parallel with the axis of rotation of the tool holder and/or via two axes of movement of a machining head supporting the workpiece holder fixing a plane perpendicular to the pivot axis.
In an embodiment, the hobbing machining takes place at the non-hardened workpiece. Alternatively or additionally, the hobbing machining is used at least for the rough machining of a gearing of the workpiece, in particular for the rough machining on a workpiece blank. The workpiece blank can have a rotationally symmetrical shape or a pre-gearing.
In an embodiment, the gear skiving machining can take place at the non-hardened workpiece. Alternatively or additionally, the gear skiving machining can at least be used for the finishing of a gearing. Depending on the embodiment, the gear skiving machining can be used for manufacturing a gearing on a workpiece blank or it can be used for finishing a gearing generated by the hobbing machining.
In a first variant, the hobbing machining and the gear skiving machining are used for manufacturing the same gearing. The hobbing machining can in particular be carried out for rough machining a gearing and consequently a gear skiving machining can be carried out at the toothed workpiece for finishing a gearing.
The terms rough machining and finishing of a gearing do not designate any absolute gearing qualities, but rather the relative gearing quality of the gearing geometry generated by the hobbing machining and the gear skiving, with the gearing quality generated by the hobbing machining being rougher or inferior with respect to the gearing quality generated by the gear skiving.
The first variant therefore combines the respective advantages of the hobbing machining and the gear skiving machining and avoids their respective disadvantages. The hobbing machining allows a high effective material removal, which then results in a tooth trace having large deviations from the ideal tooth trace due to the feed markings. The gear skiving generates a tooth trace with only small deviations due to different kinematics of engagement and small feeds, with the chip formation being associated with a high wear of the tool due to the different kinematics of engagement, in particular with the rough machining with a high material removal. The above-named problems are avoided since only the stock remaining after the hobbing machining thus has to be removed by the gear skiving, i.e. the material removal by the gear skiving is substantially reduced since the main cutting work is thus performed by the hobbing and the gearing quality is generated by the gear skiving.
In a second variant, the gearing manufactured in accordance with the present disclosure is a worm gearing. Such worm gearing arrangements were previously only able to be manufactured using complex and/or expensive special machinery. The methods disclosed in the present disclosure allow a substantially simpler manufacture and additionally provides a very high gearing quality.
The manufacture of the worm gearing in accordance with the second variant takes place by means of a method in accordance with the first variant so that the hobbing machining and the gear skiving machining are used after one another for manufacturing the worm gearing.
The method in accordance the second variant can in particular be used for manufacturing a drive element having a worm gearing of a steering drive of a vehicle.
In the first and/or second variant(s), the hobbing machining takes place by a disc-shaped profile cutter that rotates independently of the rotational movement of the workpiece holder.
The profile cutter is traveled in parallel with the axis of the workpiece holder during the hobbing machining while the workpiece is rotated about its axis such that the profile cutter generates a worm thread, with the hobbing machining taking place at an axial cross angle dependent on the lead angle of the worm gearing, with the axial cross angle approximately corresponding to the pitch angle.
In an embodiment of the first and/or second variant(s), the gear skiving takes place by a generating coupling between the gear skiving tool and the workpiece, with the gear skiving tool being traveled in parallel with the axis of the workpiece holder during gear skiving.
In accordance with the disclosure, the hobbing machining can be carried out at an axial cross angle between the hobbing tool and the workpiece in the range of +/−5° and +/−40°, in particular in the range of +/−10° and +/−20°.
The gear skiving machining can be carried out at an axial cross angle between the hobbing tool and the workpiece in the range from 90°+/−40°, in particular at an axial cross angle between the hobbing tool and the workpiece in the range of 90°+/−20°.
In a third variant, the hobbing gearing and the gear skiving machining are used for the manufacture of two different gearing arrangements of the workpiece.
Hobbing machining is in particular carried out for manufacturing a first gearing and a gear skiving machining is carried out for the manufacture of a second gearing. The first gearing has a larger diameter than the second gearing and/or forms an interference contour for the second gearing. Alternatively or additionally, workpiece contours in the proximity of one of the gearing arrangements to be machined can also represent an interference contour and can thus limit the machining capability of the gearing by means of hobbing methods.
The third variant of the present disclosure makes use of the fact that multiple gearing arrangements can be manufactured by the gear skiving that would no longer be able to be manufactured by a hobbing machining since the one gearing acts as an interference contour in the manufacturing of the other gearing by hobbing. A second gearing can in particular also be manufactured on the workpiece by gear skiving even if it has an only small axial distance from the first gearing. The hobbing machining for the first gearing therefore has the advantages of a high cutting efficiency. The relatively high wear of the gear skiving is accepted in contrast to be able to manufacture such workpieces at all, in particular without a change of machine.
In a fourth variant of the present disclosure, the gearing or gearing arrangements of the workpiece is/are one or more spur gearing arrangements.
The method in accordance with the disclosure can in particular be used for manufacturing a workpiece having a multiple gearing, in particular a shaft having at least two spur gearing arrangements arranged next to one another, in particular having different diameters. Alternatively or additionally, workpiece contours in the proximity of one of the gearing arrangements can represent an interference contour.
A method in accordance with the third variant in which the hobbing machining and the gear skiving machining are used for manufacturing two different gearing arrangements of the workpiece is used for manufacturing a workpiece having a plurality of spur gearing arrangements in accordance with the fourth variant.
In an embodiment of the third and/or fourth variant(s), the hobbing machining takes place by a hob whose rotational movement is coupled to the rotational movement of the workpiece holder, with the hob being traveled in parallel with the axis of the workpiece holder during the hobbing machining. A hob can, however, also be used in the first and/or second variant(s).
In an embodiment of the third and/or fourth variant(s), the gear skiving takes place by a generating coupling between the gear skiving tool and the workpiece, with the gear skiving tool being traveled in parallel with the axis of the workpiece holder during gear skiving.
The hobbing machining can be carried out at an axial cross angle between the hobbing tool and the workpiece in the range of 90°+/−45°, in particular in the range of 90°+/−35°.
The gear skiving machining can be carried out at an axial cross angle between the hobbing tool and the workpiece in the range of +/−45°, in particular in the range of 90°+/−35°.
An independent aspect further comprises a method for the gear manufacturing machining of a workpiece in which only a hobbing machining of the workpiece or a machining by gear skiving takes place such as has been presented within the framework of the above-described methods, in particular only a hobbing machining of the workpiece or a machining by gear skiving in accordance with at least one of the above-described variants.
The present disclosure describes a method for the manufacture of a workpiece having a worm geometry, wherein the manufacture of the worm geometry takes place by a hobbing machining of the workpiece. In one embodiment, the hobbing machining takes place by a profile cutter that rotates independently of the rotational movement of the workpiece holder. The profile cutter is traveled in parallel with the axis of the workpiece holder during the hobbing machining while the workpiece is rotated about its axis such that the profile cutter generates a worm thread.
The hobbing machining can take place at an axial cross angle dependent on the lead angle of the worm gearing, with the axial cross angle approximately corresponding to the lead angle.
Alternatively or additionally, the hobbing machining can be carried out with an axial cross angle between the hobbing tool and the workpiece in the range of +/−5° and +/−40°, in particular in the range of +/−10° and +/−20°.
The axial cross angle is set by a pivoting of a machining head of a gear cutting machine, in particular of a gear cutting machine such as will be described in more detail in the following.
Further described is a gear cutting machine in accordance with a first aspect for carrying out at least one method such as has been described above. The gear cutting machine is suitable for carrying out a method in a kinematic and/or technical control manner.
The gear cutting machine has a workpiece holder and a tool holder, with the tool holder being travelable over axes of movement of the gear cutting machine with respect to the workpiece holder. The tool holder is arranged at a machining head that is travelable over axes of movement of the gear cutting machine.
The control of the gear cutting machine is in particular designed such that at least one method as described herein can be carried out, with the carrying out taking place in an automated manner.
The gear cutting machine can in particular have a control for controlling the axes of movement of the gear cutting machine that has a function for carrying out at least one method as described herein, in particular a function for the automated carrying out of at least one method, in particular for manufacturing a plurality of identical toothed workpieces.
The control can further have functions for carrying out a plurality of the above-described alternative methods.
The functions of the control are implemented by code for controlling the axes of movement which runs on a microcontroller and/or processor of the control and which controls the axes of movement of the gear cutting machine such that it runs in an automated manner, on the gear cutting machine. An automated running does not require any intervention of a user in the control. The code can be stored in a memory of the control.
In a second, independent aspect, a gear cutting machine may have a workpiece holder and a tool holder that is travelable over axes of movement of the gear cutting machine with respect to the workpiece holder, with the tool holder being arranged at a machining head that is travelable over axes of movement of the gear cutting machine, with the machining head of the gear cutting machine having a pivot axis that stands perpendicular on the axis of the workpiece holder. The gear cutting machine is characterized in that the pivot axis has a pivot angle range of more than 90° and/or a pivot angle range that permits both a parallel and a perpendicular arrangement of the axis of rotation of the tool holder with respect to the axis of rotation of the workpiece holder.
The gear cutting machine in accordance with the second aspect is particularly suitable, kinematically suitable, to carry out a method described herein due to the large pivot angle range. The control does not necessarily have to have a function for carrying out a method described herein. The kinematic design, however, permits the control to be retrofitted and with corresponding function by new software and then the use of the gear cutting machine for carrying out a method described herein.
Alternatively or additionally, the gear cutting machine in accordance with the second aspect can be used for carrying out the hobbing machining such as has been described in more detail above, within the framework of the method described herein, in particular the hobbing machining in accordance with the above-described second variant, i.e. for manufacturing a worm gearing or a worm geometry. The gear cutting machine in accordance with the second aspect can in particular have a function for carrying out such a method, in particular for the automated carrying out.
The pivot axis has a pivot angle range of more than 110°, further of more than 130°. Alternatively or additionally, the pivot axis can have a pivot angle range that allows to pivot the axis of the tool holder in a range from −20° to +90° relative to the axis of the workpiece holder, in particular a range from −30° to +100° relative to the axis of the workpiece holder.
The gear cutting machine in accordance with the second aspect is designed in accordance with the first aspect and has the control and/or function described there.
The present disclosure further comprises software for controlling a gear cutting machine, in particular for controlling a gear cutting machine in accordance with the above-described first or second aspects having a function for carrying out at least one method described herein.
The software can in particular have a function for the automated carrying out of a method in accordance with the disclosure, in particular for manufacturing a plurality of toothed workpieces.
The software has code for controlling the axes of movement that can run on a microcontroller and/or processor of the control of a gear cutting machine and that controls the axes of movement of the gear cutting machine such that a method in accordance with the disclosure is carried out on the gear cutting machine and runs in an automated manner. An automated running does not require any intervention of a user in the control. The code can be stored in a memory of the control. The software comprises code for controlling the gear cutting machine to perform a hobbing machining of the workpiece to generate a gearing geometry of the workpiece, and code for controlling the gear cutting machine to further perform a gear skiving of the gearing geometry of the workpiece. The software may further comprise code to control the gear cutting machine to further perform the steps of the manufacturing process described herein. In an embodiment, the software may comprise code to control a pivot axis of the gear cutting machine to pivot a machining head of the gear cutting machine between the steps of hobbing machining and gear skiving.
The software is stored in a memory and/or on a memory medium.
The gear cutting machine has respective drives, in particular NC drives, for generating a rotational movement of the workpiece holder and of the tool holder about their respective axes of rotation.
The gear cutting machine has one or more linear axes, in particular NC linear axes for generating a relative movement between a tool held in the tool holder and a workpiece held in the workpiece holder.
The linear axes comprise a linear axis X1 for changing the axial spacing between the axes of rotation of the workpiece holder and of the tool holder. The linear axis X1 stands perpendicular on the axes of rotation of the workpiece holder and/or of the tool holder.
The linear axes comprise a linear axis Z1 for traveling the tool holder in parallel with the axis of rotation of the workpiece holder. The linear axis Z1 stands perpendicular on the linear axis X1.
The linear axes comprise a linear axis V1 for traveling the tool holder in parallel with its axis of rotation. Alternatively or additionally, a linear axis Y1 can be provided for traveling perpendicular to the linear axes X1 and Z1.
The pivot axis A1 stands perpendicular on the linear axes X1 and Z1 and allows a pivoting of the V1 axis.
The present invention will now be explained in more detail with reference to embodiments and to drawings.

Method for the gear manufacturing machining of a workpiece


The present invention provides various embodiments of laser systems for generating "chirp" signals. In the broadest sense, a diffraction grating is placed within a laser cavity on the face of a carrier and the motion of the carrier in its own plane causes the laser to chirp. Typically, the diffraction grating is placed in the end-reflector position of the optical path of the resonant cavity associated with the laser. By putting the diffraction grating on the outer peripheral rim of a wheel and rotating the wheel, a sequence of either up-chirp or down-chirp signals can be generated continuously. Similarly, the desired "chirped" signals can be generated by using a diffraction grating oriented radially on the face of a rotating wheel. The system also contemplates the simultaneous generation of both an up-chirp signal of one polarization and a down-chirp signal of an orthogonal polarization by using a pair of lasers and a single wheel carrying the diffraction grating on either its outer peripheral rim or its face disposed in the end-reflector positions of the lasers for simultaneously generating both the up-chirp and down-chirp signals. An optical system including a reflective mirror, a one-half waveplate, and a polarizing beamsplitter are provided at the output of the two laser system for combining the up-chirp signal and down-chirp signal for simultaneous outputting.

1. Field of the Invention
The present invention relates generally to linear frequency chirped lasers, and more particularly to a linear frequency chirped laser system that is diffraction grating driven.
2. Description of the Prior Art
The most common system used in the prior art to produce "chirping" uses an electro-optic crystal within the laser resonator. An increasing voltage applied to the crystal causes its index of refraction to change, changing the optical length of the resonator cavity and causing the resonator's longitudinal modes to tune.
The specifics of such a prior art system will be discussed for waveguide CO.sub.2 lasers. The disadvantages and problems of the prior art include, but are not limited to, the following. The electro-optic crystals are typically cadmium telluride (CdTe) having dimensions of 2 mm'2 mm in cross-section and 5 cm long. The crystals must be polished on all surfaces, with the 2 mm.times.2 mm ends being of optical quality and including antireflection coatings. The electro-optic crystals of cadmium telluride are very expensive and very fragile.
The electro-optic effect requires a ramp of 0-1600 volts across the 2 mm crystal width. The ramp must be very accurately linear, and it must be typically swept in 3 to 30 .mu.sec. This is a difficult requirement combining both high voltages and radio frequencies (RF). Furthermore, the crystal has an index of refraction of 2.7 so its optical length is 13.5 cm. This length, plus the length for the laser gain, requires that the laser resonator free spectral range (FSR) is limited to 500 MHz, and the laser cannot reach the chirp amplitude of 1 GHz desired for some applications without adding longitudinal mode suppression to an already very complex device. The present invention adds less than 2 cm to the optical length of the laser, so the laser can easily reach the 1 GHz chirp amplitude.
The electrode connections must be made between two of the 2 mm.times.5 cm faces of the crystal and the high voltage RF power must not arc to other parts of the crystal holder or flash-over from one electrode to the other.
Residual strain in the crystal or strain induced by the crystal holder causes transverse variations in the index of refraction, which distorts the optical beam and leads to optical loss within the resonator and a degraded beam quality of the laser output. The strain also causes birefringence, which converts one polarization of the light into another. This causes further optical distortions because the electro-optic effect is different for the different polarizations. It also increases the optical losses because some of the optical components will be polarization selective (the spectral line-selecting diffraction grating, for example, and possibly the waveguide bore) .
Electro-optic crystals are also piezoelectric, so the applied voltage ramp also causes a dimensional change. Because the voltage ramp occurs rapidly, a spectrum of acoustic waves are generated within the crystal. The acoustic energy will fracture the crystal if it is not removed. Even if attenuated enough so that fracture of the crystal will not occur, the acoustic energy will still induce dynamic strain-optic effects. Therefore, this energy must be removed to a very high degree of completeness.
The crystal also absorbs some optical power, which shows up as heat that must also be removed. The heat input is not uniform across the crystal, but is proportional to the optical intensity, which is most intense on the optical axis, farthest from the cooling walls. The absorbed power sets up a temperature gradient within the crystal, which causes index of refraction gradients and mechanical strains, which in turn cause strain-optic effects. These effects limit the circulating optical power and the achievable laser power and beam quality.
The electro-optic crystal must be aligned with the waveguide bore to within very exacting tolerances in both offset and angle or the insertion losses of the modulator become very large and the optical quality of the laser output drops. This requires a precision adjustable crystal holder and a very difficult alignment procedure. The crystal holder must also absorb the acoustic energy, route the high voltage RF, and provide the cooling, all without straining the crystal. The very best electro-optic modulators should have insertion losses of about 6% round-trip, and more typically they are about 10%. The present invention has an insertion loss of less than 1% round-trip.
The chirp linearity and repeatability limit the resolution of a radar system using a chirped laser transmitter. The linearity of the electro-optic driven chirp depends mainly on the linearity of the voltage ramp with time and the piezo-electric/strain-optic dynamic disturbances in the index of refraction. Other effects such as the thermal and strain-induced index of refraction gradients and birefringence will also contribute to non-linearities in the resulting optical frequency chirp. Similarly, the repeatability of the chirp slope depends not only on the repeatability of the voltage drive, but also on the dynamic strain-optic effects and the temperature dependence of the electro-optic coefficient. The prior art systems can keep deviations from linearity of the chirp ramp to 1% of the chirp amplitude, and the value of the chirp slope can be maintained constant within approximately 1% from chirp-to-chirp. The present invention very significantly improves these numbers by at least a factor of 100? The system of the present invention solves substantially all of the problems of the prior art while avoiding its shortcomings.

Diffraction grating driven linear frequency chirped laser


An eye protecting hood member made of a soft material is joined to lens rims and auxiliary temples of a spectacle frame made of a rigid material, without using any adhesive. The hood member is provided in the form of a fin between an upper side of each rim and the auxiliary temple and between an outer lateral side of each rim and the auxiliary temple for closing a space between the hood member and the face of the wearer. The lens rim is formed in the inner face of each of the upper side and the outer lateral side with at least one narrow groove so shaped as to enlarge toward its bottom. Each of the temples is formed in its inner face with at least one narrow groove so shaped as to enlarge toward its bottom. The soft material forming the hood member is filled in the narrow grooves in the lens rim and the auxiliary temple. Preferably, the narrow groove of the lens rim has a channel communicating with a lens fitting groove, and the auxiliary temple has a bore vertically extending therethrough. The soft material forming the hood member is also filled in the channel and the bore.

Goggles and the like are widely used in practicing active outdoor sports such as skiing and driving motorcycles which are movable at considerably high speeds to prevent the eyeballs from direct exposure to the wind and protect the eyes from dust particles suspending in the air.
Further in work factories wherein dust is produced, workers are under an obligation to wear dust-tight protective goggles for preventing dust particles from entering the eyes.
Goggles are widely known which have windshield and dust-tight functions and which comprise an eye protecting hood projecting from lens rims and a thick spongelike cushioning member affixed to the peripheral edge portion of the hood to be brought into contact with the face of the wearer. However, these goggles are bulky and therefore inconvenient to carry about, feel awkward when worn and are actually not in prevalent use except for skiers.
Accordingly, heretofore preferred are eye protecting spectacles of simple construction which merely have an eye protecting hood member 4 inwardly projecting in the form of a fin from the upper sides 14, 14 and outer lateral sides 13, 13 of lens rims 8, 8 as shown in FIG. 6. Nevertheless, since the lens rims 8 and the hood member 4 are integrally molded of rigid synthetic resin, these spectacles have the likelihood of injuring the skin when the projecting end of the rigid hood member 4 is forced against the face around the orbits.
To overcome this drawback, spectacles are made available which comprise a fin-shaped hood member molded of soft synthetic resin and adhered to lens rims of rigid synthetic resin, but there is no suitable adhesive which is capable of perfectly bonding the two materials, i.e., soft synthetic resin and rigid synthetic resin, which are different in characteristics. For this reason, the spectacles are insufficient in bond strength and have the drawback of permitting separation of the hood member from the lens rim if subjected to a great impact during use.
Eye protecting spectacles are therefore proposed which have eye protecting members 4 made of soft leather as seen in FIG. 7. The proposed spectacles comprise hood attaching fins 41 inwardly projecting from specified portions of the upper side 14 and outer lateral side 13 of each lens rim 8, a synthetic leather member fastened to the fins with rivets 42 to form the hood member 4, and a strip 43 of the same synthetic leather as above fastened to the hood member 4 by a rivet 42 with a temple 22 held between the strip and the hood member. However, the eye protecting spectacles require much labor for cutting the synthetic leather and riveting the leather components, and therefore have the drawback of being very expensive to make.
In view of the foregoing drawbacks, we have developed an eye protecting device which comprises a spectacle frame of rigid synthetic resin and an eye protecting hood member made of a soft synthetic resin material and firmly joined to the frame in intimate contact therewith without using any adhesive.

Structure for attaching member for protecting eyes from wind and dust


Structures, methods, and systems for enhanced erasing operation for non-volatile memory are disclosed. In one embodiment, a semiconductor device which comprises a memory cell array having a plurality of non-volatile memory cells, a negative voltage generating circuit for applying a negative voltage to a word line of the memory cell array during an erasing operation of the memory cell array, and a positive voltage generating circuit for applying a positive voltage to a well of the memory cell array when the negative voltage reaches a predetermined voltage.

Recently, rewritable non-volatile memories have been widely used for many electronic devices such as mobile phone terminals and digital cameras. FIG. 1 is a view illustrating a cross-section of a non-volatile memory cell 12 having a floating gate as a charge storage layer. In FIG. 1, an n-type well 31 is formed in a semiconductor substrate 30, and a p-type well 32 is formed on the n-type well 31. A well 33 is composed of the n-type well 31 and the p-type well 32. An n-type source region 34 and a drain region 36 are formed on the p-type well 32. A tunnel oxide film 42, a floating gate 44, an insulating film 46, and a control gate 48 are formed on the p-type well 32 between the source region 34 and the drain region 36. The control gate 48 is connected to a word line (not shown). An n-electrode 38 for applying a voltage to the n-type well 31 is formed and connected to the n-type well 31. A p-electrode 40 for applying a voltage to the p-type well 32 is formed and connected to the p-type well 32.
When a writing operation to the memory cell 12 is performed by accumulating a charge in the floating gate 44, an electric field is applied between the source region 34 and the drain region 36. A positive electric potential is applied to the well 33 via the control gate 48 and the word line. Thereby, hot electrons are injected into the floating gate 44, and a charge is accumulated in the floating gate 44. On the other hand, when an erasing operation is performed to the memory cell 12, that is, when the charge is erased from the floating gate 44, a negative electric potential is applied to the well 33 via the control gate 48 and the word line. Thereby, due to a Fowler-Nordheim tunneling phenomenon, electrons in the floating gate 44 tunnel to the p-type well 32 through the tunnel oxide film 42, thus erasing the charge in the floating gate 44.
FIG. 2 is a timing chart of a voltage Vwell of the well 33 (e.g., the n-type well 31 and the p-type well 32) and a voltage Vword of the word line (control gate) during the erasing operation. At t0, erasing of the memory cell 12 starts. The word line voltage Vword of a selected word line gradually increases in a negative direction. The well voltage Vwell gradually increases in a positive direction. At t1, the word line voltage Vword becomes a constant voltage Vword0. At t2, the well voltage Vwell becomes a constant voltage Vwell0. When the erasing of the memory cell 12, which is connected to the selected word line, is completed at t3 or later, the word line voltage Vword gradually becomes 0. At t4 or later, the well voltage Vwell gradually becomes 0.
However, between t0 and t2, the word line voltage Vword may be raised to 0V as in point A of FIG. 3 rather than being continually decreased. This may be due to capacitive coupling between the well 33 and the word line WL arranged on the well 33. Since the well 33 is commonly provided in many memory cells 12, an electrostatic capacitance (parasitic capacitance) of the well 33 is extremely large compared to that of the word line WL. Accordingly, the word line voltage Vword may be raised when the well 33 is charged. Due to the rise of the word line voltage Vword, the word line voltage Vword may not reach the constant voltage Vword0 at t1, which is the voltage that the word line voltage Vword is supposed to reach. Instead, word line voltage Vword may be kept constant at a voltage Vword0′ at t1. The disruption of the potential between the well voltage Vwell and the word line voltage Vword due to the capacitive coupling may delay and/or disrupt the erasing operation of the memory cell 12.

Enhanced erasing operation for non-volatile memory


Disclosed herein is a method of manufacturing a semiconductor device, including the steps of: forming an interlayer insulating film on a semiconductor substrate; forming a metal mask on the interlayer insulating film; forming a pattern trench in the metal mask and the interlayer insulating film by etching away parts of the metal mask and the interlayer insulating film; forming a conductive layer on the interlayer insulating film so as to fill in the pattern trench; and polishing the excessive conductive layer and the metal mask on the interlayer insulating film so as to leave the conductive layer in the pattern trench.

1. Field of the Invention
The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of manufacturing a semiconductor device in which a single damascene process or a dual damascene process is adopted.
2. Description of the Related Art
A copper (Cu) wiring gives a semiconductor device a lower resistance, a smaller capacity and higher reliability than an aluminum (Al) alloy wiring line gives. Thus, the importance of the copper wiring has increased in a micro-element in which circuit delay due to a parasitic resistance and a parasitic capacity of a wiring are dominant. In general, since unlike the Al alloy wiring, it is not easy to etch away Cu by utilizing a dry etching method, a single damascene process is generally accepted for Cu. The single damascene process is a process for a wiring. In this process, a predetermined trench is previously formed in an interlayer insulating film formed of, for example, a silicon oxide (SiO2) film, a wiring material is filled in the predetermined trench, and thereafter the excessive wiring material is removed by utilizing a chemical mechanical polishing (CMP) method or the like, thereby forming the desired wiring. Moreover, a dual damascene method in which after a contact hole and a wiring trench are formed, a wiring material is collectively filled in the contact hole and the wiring trench, and the excessive wiring material is then removed is also effective in reduction in the number of processes and the cost. This technique, for example, is disclosed in Japanese Patent Laid-open No. Hei 11-45887.
As a design rule for LSI has proceeded to scale down, a rate containing a barrier metal used to prevent scattering in a surface of a Cu wiring and grain boundaries or diffusion of Cu into an insulating film has increased. As a result, it is a problem that an abrupt increase in wiring resistance is generated due to an influence of such an increase or the like, which causes reduction in a processing speed of a semiconductor device. Moreover, the barrier metal is deposited in overhang-like shape in an upper end of the trench or the contact hole by utilizing a PVD method. As a result, there is also encountered such a problem that as the LSI design rule has proceeded to scale down, it is easy to generate a void when a wiring material (Cu in a normal case) is deposited.
As for the means for solving the above-mentioned problems, a method of thinning a barrier metal, or a method of forming a barrierless structure without using any of the barrier metals is well known. With regard to the thinning of the barrier metal, there is known a method of simply thinning the barrier metal deposited by utilizing the PVD method which is generally used. In addition thereto, recently, the barrier metal which is deposited by utilizing an atomic layer deposition (ALD) method has come to attract attention. In addition, with regard to the barrierless structure, in addition to a method of using a film which has a low diffusion coefficient of Cu and which is made of, for example, benzocychrobutene (BCB) as an insulating film, a method is known in which Cu is mixed with a metal such as magnesium (Mg) or aluminum (Al), whereby the barrier property is enhanced while an increase in wiring resistance is suppressed. This method is disclosed for example in T. Usui et al., "Low Resistive and Highly Reliable Cu Dual-Damascene Interconnect Technology Using Self-Formed MnSixOy Barrier Layer", Proceeding of IEEE IITC, 2005.
The barrierless structure or the thinning of the barrier metal makes it possible to reduce the wiring resistance of the semiconductor device. However, the following problems are caused in the CMP process when the wiring is formed. Hereinafter, these problems will be described by giving the barrierless structure as an example.
FIG. 4A is a process cross sectional view before the CMP is performed in the single damascene process or the dual damascene process. As shown in FIG. 4A, a wiring trench is formed in an interlayer insulating film 102 on a base substrate 101, and a conductive layer 104 made of Cu or the like is formed over the interlayer insulating film 102 so as to fill in the wiring trench. Normally, a swelling amount of conductive layer 104 in a region having a high wiring density becomes high, while a swelling amount of conductive layer 104 in a region having a low wiring density becomes low.
After that, the conductive layer 104 is subjected to the CMP in order to remove the excessive conductive layer 104 on the interlayer insulating film 102. The CMP includes a first step of flattening the conductive layer 104 by removing the excessive conductive layer 104 made of Cu, and a second step of removing surfaces of the conductive layer 104 and the interlayer insulating film 102 while the flattening of the conductive layer 104 is maintained. In the second step, in general, in order to remove a facet of the wiring which is generated during the processing, a slurry for substantially equalizing the polishing rates of the conductive layer 104 and the interlayer insulating film 102 to each other is used, and the polishing is performed until a desired wiring height is obtained while the flattening is maintained.

Method of manufacturing semiconductor device


An access device comprises a thin-walled sheath that is insertable into a patient through a small surgically created incision. The incision may be created using a cutdown or a percutaneous method such as that known as the Seldinger technique. Once inserted and advanced to the target surgical site, the sheath is selectively, and controllably, expanded to a desired diameter. The thin wall of the sheath is fabricated from a rectangular piece of material such as metal or plastic with two cut edges. The rectangular piece of metal or plastic is rolled tightly to create the small diameter configuration that is inserted into the patient. A cam or control member is affixed to the innermost edge of the rectangular piece of metal or plastic. The control member extends to the proximal most portion of the sheath. By rotating the control member, the operator causes the thin wall piece of rolled material to unfurl into a larger or smaller diameter, depending on the direction of rotation. A mechanical lock at the distal end of the sheath permits the control member to be selectively constrained from rotation and thus lock the sheath diameter in place.

1. Field of the Invention
This invention relates to medical access devices and, in particular, to expandable medical access devices for providing minimally invasive surgical access for various surgical procedures.
2. Description of the Related Art
A wide variety of diagnostic or therapeutic procedures involve the introduction of a device through a natural or artificially created access pathway. As such, minimally invasive access systems have been developed to generate such pathways. A general objective of these access systems is to minimize the cross-sectional area of the puncture, while maximizing the available space for the diagnostic or therapeutic instrument. Procedures that utilize access systems include, among others, a wide variety of laprascopic diagnostic and therapeutic interventional procedures.
In many of these procedures, it is advantageous to provide a self-retaining access system that provides tissue retraction throughout a surgical procedure without the continued attention of a human assistant. Self-retaining retraction provides the operator with the ability to choose the tissue and separation plane to provide adequate exposure for a given surgical procedure. Examples of tissues retractors commonly known in the surgical art include the Richardson retractor, the Alm retractor, the Balfour retractor, the Rigby retractor and the like.
In contrast to minimally invasive access systems, surgical approaches, by their open nature, generally require the elements of incision, dissection, hemostasis, and mechanical closure. The incision is typically accomplished using a scalpel, a saw, or an electrosurgical cutting device. Dissection is typically accomplished using a scalpel, electrosurgical cutting device, or a blunt object such as a pair of forceps or an obturator. Hemostasis control is generally performed using electrocautery, wound packing, and suction drainage to a collection system. Mechanical closure is generally accomplished using sutures, staples or clips.
Surgical approaches afford direct surgical vision, direct tactile feedback along with the intrinsic ability to enlarge the field of view simply by enlarging the incision and resetting the self retaining retractor. While large incisions may heal as quickly as small ones, they are a source of extended patient discomfort and poor cosmetics along with expensive recovery periods, both in and out of the hospital.
Many surgical procedures have been converted to minimally invasive, laparoscopic procedures that avoid large incisions, reduce hospital stays and costs while producing similar short- and long-term results. Such procedures typically involve minimally invasive access systems as described above. However, minimally invasive access systems for surgical procedures that do not invade body cavities, such as the abdomen or thorax may not be suited for traditional laparoscopic visualization. Such is the case in orthopedic procedures (e.g., joint or spine access). In these cases, a surgeon often is forced to rely on the blunt placement of consecutively larger cannula, with or without the benefit of a dilator to reach the desired surgical site. Surgical instruments are then inserted through the cannula to reach the target site. Surgical exposure is limited by the accurate placement of the cannula, location of pathology and diameter of the cannula. Once the skin incision of adequate size is made, the axial shear force of sequentially placed dilators, with increasing diameters, creates an operative tunnel to reach the desired surgical site.
The rigid walls of the cannula exert a tamponade pressure to provide hemostasis during the session. Distal visualization is often provided by a rigid scope while operative maneuvers are accomplished with laparoscopic or extended length instruments placed through the cannula. Radial pressure holds the cannula over the operative site freeing the operative team from retraction duties as well as removing potential obstructive nuisances from the immediate surgical field. Enlarging the surgical field requires placement of a larger cannula with an axially directed shear force. Such placement of a new cannula carries with it the possibility of loosing anatomic landmarks during the device transition. Since a majority of the tissue plane separation is achieved with blunt expansive force, rather than by tissue shearing, and is maintained with radial force, recovery is often less traumatic than that encountered with open surgery. Should the operative procedure require expansion with incision and traditional retraction applied, the recovery course may be longer and costs higher than if the minimally invasive approach was used.
Traditional laparoscopy also uses trocars, with diameters ranging from 5 to 20 mm, to gain access to the abdomen or chest. Most procedures are successfully completed through three or four trocar sites. There are cases, such as removing an organ or tissue for transplant, when time and labor burden could be reduced by the ability to enlarge a trocar site. Surgical incision sites must enlarged carefully, however, because most operators are reluctant to expand surgical exposure at the risk of losing the anatomic landmark.
A need therefore remains for improved access technology needed to create a tunnel to a target surgical site in such a way that trauma to the tissue is minimized. Preferably, such technology provides for controllable tissue dilation once the initial tunnel is created.


This invention relates to an isolated nucleic acid fragment encoding a plant lecithin:cholesterol acyltransferases. The invention also relates to the construction of a chimeric gene encoding all or a portion of the plant lecithin:cholesterol acyltransferases, in sense or antisense orientation, wherein expression of the chimeric gene results in production of altered levels of the plant lecithin:cholesterol acyltransferases in a transformed host cell.

Phosphatidylcholine-sterol O-acyltransferase (EC 22.214.171.124) transfers acyl groups from phosphatidylcholine to sterols. This enzyme is also known as lecithin:cholesterol acyltransferase (LCAT) and belongs to the class of CoA-independent acyltransferases. This enzyme is found associated with high-density lipoproteins (HDL) and forming a complex with its activators Apolipoprotein (apo)-AI and apo-D. HDLs are believed to promote the process of reverse cholesterol transport. This process involves efflux of cellular cholesterol, cholesterol esterification and lipid transport and exchange. Apo A-I and lecithin-cholesterol acyltransferase play a crucial role in reverse cholesterol transport.
The role of LCAT in plants will presumably be different from mammalian systems given the negligible levels of cholesterol found in plant oils. However, plants have a complex combination of membrane sterols that can change with environmental conditions as well as developmental determination. LCAT may function as the phosphatidylcholine acyl-exchange enzyme which moves unsaturated acyl groups into phosphatidylcholine for desaturation and out of it for incorporation into triacylglycerols. Overexpression of LCAT may lead to increased lipid metabolism and fluidity of membranes increasing resistance to heat and/or cold shock. Overexpression or cosuppression of LCAT may also be useful to genetically alter the content of phytosterol or lecithin in grains.


The invention describes a focusing drive for optical instruments that has, in addition to a pinion (1) and toothed rack arrangement (1, 2), slide rods (4) as guidance means for continuously changing the relative position of optical assemblies with respect to one another. The toothed rack (2) has a plurality of support elements (3) that are arrangedxe2x80x94for example in angled fashionxe2x80x94on either side of its longitudinal extent. The support elements (3) are designed so that they have a shallow S-shape in cross section. In addition, they are dimensioned in such a way that they touch the contact surface of the one housing module (5) only with their planar end regions (3a). The result is a resilient or flexing motion upon actuation of the pinion (1), thus achieving smooth and zero-backlash adjustment.

The present application claims priority under 35 U.S.C. 119 of German Patent Application No. 100 23 568.9 filed May 15, 2000.
The invention concerns a focusing drive for optical instruments, in particular microscopes. It has a pinion and toothed rack arrangement as well as guidance means for displacing a device component with respect to a stationary further component.
With adjustment mechanisms of this kind, the problem often exists that aging and wear phenomena occur as the toothed rack and pinion interact, and jerky adjustment operations can result. The toothed racks must be carefully centered and aligned on the component that is to be displaced. This results in time-consuming and cost-intensive assembly procedures. Combined with the aforementioned wear susceptibility of such systems, with frequent use it is therefore impossible to obtain smooth, zero-backlash guidance over a long period of time.
It is therefore the object of the present invention to eliminate the disadvantages of known focusing drive solutions and to describe a smooth and zero-backlash guidance mechanism that moreover can be installed in the optical device without alignment elements, resulting in economical manufacture.
This object is achieved, according to the present invention, by a focusing drive of the kind cited initially in that it is fitted with a plastic toothed rack that is equipped with a plurality of support elements and comprises parallel-mounted slide rods as guidance means. Special support elements are arranged on the toothed rack on either side of its longitudinal extent. These can be cantilevered from the toothed rack in arm-like fashion. The support elements are advantageously located on the toothed rack in paired fashion, so that one left arm and one right arm form, so to speak an arm xe2x80x9cpair.xe2x80x9d It is also possible for the support elements to be cantilevered in L-shaped fashion on the toothed rack. In a particular embodiment of the present invention, the support elements are of resilient configuration. For example, they can have a stepped shape or be slightly S-shaped in longitudinal section. The support elements rest with their respective end regions against the device module that is to be displaced. A one-piece configuration of the toothed rack is advantageous.
The focusing drive according to the present invention furthermore has parallel slide rods as guidance means for the displacement of a device module relative to a stationary device stand. These rods can be positioned loosely in V-grooves, the grooves being provided on the one hand in the device module to be displaced and on the other hand in the stationary device stand. According to the present invention, the slide rods are held under compressive stress in their respective positions. This is implemented by the fact that the device stand externally surrounding the slide rods is physically equipped and dimensioned so as to result in a pressure-generating clamping effect on the slide rods. It is thereby possible to provide means for stable retention and controlled modification of the pressure. These means can comprise a rotary knob that is under a spring preload. Particularly significant is the fact that the slide rods are made of an electrically conductive plastic material, and are circular in cross section. Because of the specific material selected, it is possible to create a focusing drive in which displacement along the slide rods is accomplished in dry sliding fashion. It is also possible to provide means for adjusting or changing the drag of the focusing drive. According to the present invention, this focusing drive is intended for use in antistatic optical devices, in particular microscopes.


The invention relates to a power unit, in particular for a hybrid vehicle, comprising a two-cylinder reciprocating piston engine comprising two pistons guided in two cylinders in tandem arrangement, and two counter-rotating crankshafts connected to the pistons by connecting rods, a generator which is rotatable in the same direction as the first crankshaft and in the opposite direction to the second crankshaft, and a balancer shaft which is rotatable in the same direction as the second crankshaft and in the opposite direction to the first crankshaft. The generator is operatively connected directly to the first crankshaft by a first traction mechanism and the balancer shaft is operatively connected directly to the second crankshaft by a second traction mechanism. The balancer shaft and/or the second crankshaft support(s) a flywheel mass element. The invention further relates to a vehicle, in particular a hybrid vehicle, having such a power unit.

Power units having a two-cylinder reciprocating piston engine, the pistons of which are guided in two cylinders in tandem arrangement and which comprise two counter-rotating crankshafts connected to the pistons by connecting rods are generally known from the prior art. In particular DE 10 2014 115 042 A1, DE 10 2014 115 041 A1, DE 10 2014 115 044 A1 and EP 2 633 166 B1 which trace back to the applicant exhibit such power units.
Common to the known power units is that they comprise a generator which is operatively connected to one of the crankshafts. Some variants of known power units additionally comprise a balancer shaft which is likewise operatively connected to one of the crankshafts.
The previously known power units can be used for a diverse range of applications. They are preferably used in hybrid vehicles. The previously known power units are in particular designed for a rated electrical power output of approximately 85 kW.


A support structure for a plunger employed in a plunger pump, comprises a pump housing, a cylinder firmly fitted into a cylindrical hollow defined in said housing, a plunger slidably enclosed in the cylinder to provide a pumping action, a stopper arranged on an inner peripheral surface of the cylinder, and an engaging portion arranged on the outer peripheral surface of the plunger, for engaging with the stopper and for restricting an axially projecting amount of the plunger relative to the cylinder.

1. Field of the Invention
The present invention relates to a structure for a plunger pump which can be optimally applied for an anti-skid brake control system for an automotive vehicle, and specifically to a support structure for a plunger operably employed in a plunger pump.
2. Description of the Prior Disclosure
Recently, there have been proposed and developed various automotive brake control systems associated with at least one of advantageous braking force control systems, namely a traction control system generally abbreviated as a TCS which is provided for suppressing excessive driving force exerted on driven wheels during quick depressing operation of an automotive accelerator pedal, such as quick starting, quick acceleration, or the like, and an anti-skid brake control system generally abbreviated as an ABS which is provided for preventing brakes from locking vehicle wheels during quick braking or during braking on a low frictional road surface so as to provide maximum effective braking. Of these braking force control systems, the ABS generally includes at least one brake fluid reservoir associated with either the front-wheel side or the rear-wheel side for temporarily storing the brake fluid returned from the wheel cylinders, and an auxiliary pump unit arranged for supplying the brake fluid in the wheel cylinders to the brake fluid reservoir so as to reduce the wheel cylinder pressure during the anti-skid brake control. The ABS also includes a pressure intensifying valve and a pressure reducing valve both connected to the associated wheel cylinder. The pressure intensifying valve is provided between the outlet port of the master cylinder and the inlet port of the wheel cylinder so as to establish or block the brake fluid flow from the master cylinder to the wheel cylinder, while the pressure reducing valve is provided between the brake fluid reservoir and the wheel cylinder so as to return the brake fluid in the wheel cylinder through the brake fluid reservoir and the ABS pump to the master cylinder. The ABS is operated so that the wheel slippage can be maintained within a predetermined slippage criterion by reducing, holding, and increasing the wheel cylinder pressure in response to the road condition. Traditionally, the pressure intensifying valve and the pressure reducing valve are each comprised of a two-position electromagnetic solenoid valve. Alternatively, the pressure intensifying valve and the pressure reducing valve are both comprised of a single three-position solenoid valve. For instance, the pressure intensifying valve is closed and the pressure reducing valve is opened in order to control the wheel slippage within an acceptable slippage, when the wheel cylinder pressure is reduced during the anti-skid brake control. The auxiliary pump unit is usually referred to as an "ABS pump". One such ABS pump has been disclosed in Japanese Patent First Publication Tokkai Heisei No. 2-286883.
As shown in FIG. 4, the above-noted conventional ABS pump unit is comprised of a plunger pump. Referring now to FIG. 4, the plunger pump comprises a pump housing 1 defining a cylindrical hollow 2 therein, a cylinder 3 inserted and fixed into the cylindrical hollow 2, and a plunger 4 slidably enclosed in the cylinder 3. The pump housing 1 is integrally formed as the same housing as the pressure intensifying and reducing valve being comprised of a three-position solenoid valve, for example. As clearly seen in FIG. 4, the cylinder 3 has a radial opening 3a, while the plunger 4 is formed with a radial opening 4a and an axial bore 4b. The plunger pump includes a plunger biasing means, such as a coil spring 7 comprised of a compression spring, for normally biasing the plunger 4 to a drive cam 8. The plunger pump also includes a check valve means for regulating the outlet pressure of the plunger pump. The check valve means is comprised of an inlet check ball 6 and a coil spring 5 whose spring constant determines a setting pressure of the check valve means. Conventionally, the drive cam 8 is comprised of an eccentric cam having a driven connection with a direct current motor. The plunger pump is driven by virtue of the DC motor. During operation of the plunger pump, the brake fluid temporarily stored in the brake fluid reservoir is introduced through the radial openings 3a and 4a into the axial bore 4b. Thereafter, the brake fluid in the axial bore 4b is fed through the inlet check valve 6 and 5 to an outlet port of the plunger pump, in accordance with a reciprocating motion of the plunger 4.
As set forth above, since the plunger 4 of the prior art plunger pump is normally biased in a direction outwardly projecting from the interior of the cylinder 3 by means of the coil springs 7 and 5, when a sub-assembly being in a state wherein the plunger 4, the return spring 7 for the plunger, the inlet check ball 6, and the return spring 5 for the check ball 6 are all assembled in the cylinder 3, is inserted into the cylindrical hollow 2 of the housing, there is a tendency for the plunger 4 and the check ball 6 to fall out of the cylinder 3. Therefore, when assembling the sub-assembly with the housing, a working efficiency is lowered and consequently a manufacturing cost is increased. Due to the outwardly projecting plunger of the sub-assembly, a degree of freedom for assembling is limited. That is, although the sub-assembly can be upwardly assembled into the cylindrical hollow 2 of the housing 1 in its vertical direction, it is difficult to downwardly insert the sub-assembly into the cylindrical hollow 2 of the housing in a vertical direction or to horizontally insert the sub-assembly into the cylindrical hollow 2, because the plunger and the inlet check valve both tends to fall out of the cylindrical hollow of the pump housing.


Novel systems and apparatuses for conveying particulate media are disclosed. One such system may include a conveying tank configured to receive media and push it out to a media distribution valve to be distributed to any desired destination. The media distribution valve is preferably a multi-port, pinch valve having a drain to dump any residual media not distributed through the distribution valve. One or more blast dispensers may be in communication with the media distribution valve. Each blast dispenser may be in communication with a blast chamber, which also may be in communication with the media distribution valve. A screen classifier may be in communication with the media distribution valve to receive and screen media from the blast chamber, for example, before being conveyed, if desired, through one or more conveying tanks through the media distribution valve.

The present disclosure relates generally to conveying technologies and particularly to particulate media conveying systems and apparatuses.
Myriad techniques exist to convey particulate media in many different industries. One technique involves pneumatic conveying typically used for bulk solids. These systems may be categorized as vacuum or negative pressure, positive pressure, or a combination of the two. They can be operated in dilute-phase where there is a lot of air and the media moves quickly, or in dense-phase where the media moves slowly or in gulps.
Vacuum systems are limited to a 15 psi pressure differential (absolute vacuum) so they are limited in how hard they can pull the media along, but this technique is by far the most common way to convey pneumatically. Very low bulk density materials will get blown around in even the slightest breeze. Cereals, powders, and grains are also easily moved with vacuum. As the intake is atmospheric, a pick-up wand may be pushed down into the bulk solid and it will get vacuumed up. However, materials with higher bulk density, such as steel shot that is physically dense and aerodynamic, will not convey or convey very slowly. Indeed, a vertical vacuum pipe will have a hard time lifting a heavy and aerodynamic particle because the air just goes around it.
Positive pressure conveying systems are not limited to 15 psi. The media to be conveyed is put into a closed vessel that is subsequently pressurized. The vessel is typically shaped so the pressurized air tries to escape the vessel through the media, pushing the media along.
Screw conveyors are another popular conveying technology. A long pipe has a helical feed wire or screw put down the middle. Turning either the screw (typical) or tube (rare) will cause media to feed up the tube. The tube has a limit to how steep it can be, particularly with free-flowing materials.
Bucket elevators are large and mechanically complex systems where a series of buckets ride along on a pair of chains. The buckets are passed under a pick-up station where media is deposited. The buckets then follow the conveyor, usually upwards and sideways only, to a single drop-off station where the buckets are inverted. Such systems are quite varied. For example, some may be belt driven, employ a continuous belt instead of buckets, manufactured from a variety of different materials, etc.
The vast majority of particulate media conveying systems for shot peening use vacuum conveying or bucket elevators. Vacuum conveying limits these systems to using smaller media, as larger media will not convey up long vertical runs, as discussed above. The bucket elevators are used in machines that may put out hundreds to thousands of pounds of shot per minute. These technologies are both single pick-up and single drop-off. In an effort to overcome the one-source to one-destination shortcoming, these systems stack all their equipment and use gravity to convey between items. Consequently, very tall machines must be employed that have only one flow path the media can follow. Conventional shot peen systems are thus typically enormous, expensive, and limited to conveying media with a single pick-up and drop-off.
Accordingly, novel systems and apparatuses for conveying multiple medias with minimization or elimination of cross-contamination, with multiple pick-up and drop-off locations, and compact size are therefore desired.

Particulate media conveying systems and apparatuses


The present invention relates to novel bacteriophages and bacteriophage cocktails containing the novel bacteriophages and or parts and/or products of them, all of them belonging to the Caudovirales order. The novel bacteriophages and the bacteriophage cocktails containing the novel bacteriophages and or parts and/or products of them are Salmonella specific bacteriophages and have lytic activity against Salmonella.

Salmonellosis, due to non-typhoid Salmonella enterica serovars, is one of the most frequently reported food-borne diseases worldwide. Since 1993 to 2003, Enteritidis (84%), Typhimurium (7%), Virchow (1%), Infantis (1%) and Blockley (1%), were the serovars of S. enterica mainly isolated from human salmonellosis in European Union. More recently, data from 2006 to 2007 corroborate that Enteritidis and Typhimurium continue to be the most prevalent, although an increase of Typhimurium (16.5%) and a decrease of Enteritidis (64.5%) must be noted (EFSA, 2010).
Poultry and swine are known reservoirs of these zoonotic pathogens. S. Enteritidis is the most frequent cause of human salmonellosis at European Community level. In general, this serovar is also the most frequently isolated from poultry meat and especially in table eggs, whereas it is less commonly found from pigs and cattle and products thereof. The second most prevalent serovar in humans, S. Typhimurium, is the most frequently isolated serovar in pigs, cattle and products thereof and was also among the top three serovars isolated from broilers and table eggs (EFSA, 2010). It is also well documented that in the last decade, the antibiotic resistance is increasing in non-typhoid S. enterica, which means that animals are both pathogen and resistance reservoirs.
Due to the great concern about Salmonella zoonoses, a new Salmonella control program in breeding flocks of Gallus gallus was implemented. This control program aim to meet the Salmonella reduction targets set by the Regulation (EC) No 1003/2005 and covers the following serovars: S. Enteritidis, S. Typhimurium, S. Infantis, S. Virchow and S. Hadar. Likewise, a control or monitoring program for Salmonella in pig herds or slaughter pigs have been implemented in different countries with the aim to have more robust data about Salmonella prevalence in swine production. Different strategies and measures to reduce Salmonella have been proposed. In fact, the intensified control of Salmonella in animal populations, particularly in poultry, and a better hygiene throughout the food chain should be the cause of the decrease of the notification rate of Salmonella cases in the European Union. One of these measures has been the use of life or inactivated vaccines to control S. Enteritidis in poultry. However, some authors doubt of its long term effectiveness (Baumler et al., 2000; Rabsch et al., 2000). In this context, it is necessary to open the scope for further research to explore new approaches to existing ones, and new weapons with which to combat these zoonotic pathogens.
Within this aim, the potential use of bacteriophages in human and animal therapy has been extensively reviewed in these lasts years (Barrow and Soothil, 1997; Barrow, 2001; Sulakvelidze et al., 2001; Summers, 2001; Merrill et al., 2003; Matsuzaki et al., 2005; Parisien et al., 2008;). Moreover, its interest as biocontrol agents of zoonotic bacteria in food and animal production and also of others involved in biodeterioration has also arisen and some strategies have been proposed (Barrow and Soothil, 1997; Joerger, 2002; Callaway et al., 2004; Greer, 2005; Hudson et al., 2005). The special characteristics of phages among which are its high specificity and its ability to selfreplicate when infecting, make them especially attractive to prevent food-borne illness, by using them as biocontrol agents in poultry and swine industries and in food production. However, the narrow host-range of bacteriophages is a great restriction to find good candidate phages for bacteriophage therapy against Salmonella enterica because these phages must be able to infect a wide range of strains and serovars of this bacterial species.
There is a consensus about lytic bacteriophages are the best suitable to achieve a significant reduction of bacterial populations due its rapid bacterial killing. Furthermore, safety criteria related to the spread of virulence genes or antibiotic resistance that could be in the phage genome must also be taken into account. Therefore, it is necessary to obtain genomic data demonstrating the impossibility of a lysogenic cycle and the absence of both potential virulence factors and/or antimicrobial resistance genes in the genomes of phage for therapy applications. In addition, it must be noted that the effectiveness of phages in food is likely to vary with each phage, each food matrix, and with the conditions of application including environmental factors (EFSA, 2009).
There are some works testing the effect of different bacteriophages for their inhibitory effect against Salmonella enterica. Thus, it has been reported a reduction of S. Typhimurium in the digestive tract of chickens after oral inoculation of lytic bacteriophages, although high titter of bacteriophages were needed and the inoculation was performed soon after infection to maximized the effect (Berchieri et al., 1991). More recently, much more significant decreases in S. Enteritidis in the cecal contents of broilers orally inoculated with bacteriophages, some of them belonging to the Myoviridae and Siphoviridae family, have been obtained at different times (Fiorentin et al., 2005a; Atterbury et al., 2007; Filho et al., 2007; Borie et al., 2008) and also in S. Typhimurium in experiments that combine the oral inoculation of bacteriophages with competitive exclusion cultures (Toro et al., 2005). In another field of application which included food safety, treatment with bacteriophages also reduced the concentration of S. Enteritidis in poultry products and turkey (Goode et al., 2003; Higgins et al., 2005; Fiorentin et al. 2005b; Bigwood et al., 2008). However, all these works are partial studies because any of them show nor a morphological and genomic characterization of bacteriophages, the phage host range, the efficiency of bacteriophages for reducing Salmonella in poultry over long periods and its efficiency in different matrices and neither some criteria related to safety.
The present invention describes the novel lytic bacteriophages UAB_Phi20 and UAB_Phi78, belonging to the Podoviriade family and UAB_Phi87, belonging to the Myoviridae family, all of them of the Caudovirales order. Those bacteriophages are Salmonella specific bacteriophages that infect different serovars of Salmonella and a high percentage of clonally unrelated strains of the serovars Typhimurium and Enteritidis. Those bacteriophages maintain their infective ability at a wide pH range. The genome of those bacteriophages does not include any known or similar gene to those involved in bacterial virulence.
The present invention also describes bacteriophage cocktail compositions containing at least one of the bacteriophages and/or parts and/or products of the bacteriophages of the invention. Those cocktail compositions can also contain other lytic bacteriophages and/or parts and/or products of them. The novel bacteriophages, when administered to animals, are useful for the bacteriophage therapy over the time of different Salmonella serovars. The present invention refers to the use of these novel bacteriophages and the novel bacteriophage cocktail compositions to reduce the concentration of different Salmonella serovars, providing doses and schedule of administration in animals and in different matrices. The invention refers to the use of the novel bacteriophages and the novel safe phage cocktail compositions as an antimicrobial for the biocontrol of populations of Salmonella in animal therapy and livestock in general as well as a sanitization and sterilization composition to be applied on slaughterhouses, animal transportation, food processing industries and foods.


A multiplexed pixel display includes a plurality of pixel electrodes, a plurality of storage elements, a first voltage supply terminal, a second voltage supply terminal, a common electrode, and a plurality of multiplexers each selectively coupling an associated one of the pixel electrodes with one of the first voltage supply terminal and the second voltage supply terminal responsive to a value of a data bit stored in an associated one of said storage elements. A controller is configured to sequentially write each bit of multi-bit data words to the storage elements, and assert, while each bit is stored in the storage elements, a first predetermined voltage on the first voltage supply terminal, a second predetermined voltage on the second voltage supply terminal, and a third predetermined voltage on the common electrode, for a time dependent on the significance of the stored bit. Various alternate controllers facilitate the use of additional driving schemes.

1. Field of the Invention
This invention relates generally to electronic driver circuits, and more particularly to a novel circuit and method for driving a display by multiplexing predetermined voltages to achieve modulation between saturation and threshold voltages of pixel electrodes in a liquid crystal display.
2. Description of the Background Art
FIG. 1 shows a single pixel cell 100 of a typical liquid crystal display. Pixel cell 100 includes a liquid crystal layer 102, contained between a transparent common electrode 104 and a pixel storage electrode 106, and a storage element 108. Storage element 108 includes complementary data input terminals 110 and 112, data output terminal 114, and a control terminal 116. Responsive to a write signal on control terminal 116, storage element 108 reads complementary data signals asserted on a pair of bit lines (B+ and B−) 118 and 120, and latches the signal on output terminal 114 and coupled pixel electrode 106.
Liquid crystal layer 102 rotates the polarization of light passing through it, the degree of rotation depending on the root-mean-square (RMS) voltage across liquid crystal layer 102. The ability to rotate the polarization is exploited to modulate the intensity of reflected light as follows. An incident light beam 122 is polarized by polarizer 124. The polarized beam then passes through liquid crystal layer 102, is reflected off of pixel electrode 106, and passes again through liquid crystal layer 102. During this double pass through liquid crystal layer 102, the beam's polarization is rotated by an amount which depends on the data signal being asserted on pixel storage electrode 106. The beam then passes through polarizer 126, which passes only that portion of the beam having a specified polarity. Thus, the intensity of the reflected beam passing through polarizer 126 depends on the amount of polarization rotation induced by liquid crystal layer 102, which in turn depends on the data signal being asserted on pixel storage electrode 106.
Storage element 108 can be either an analog storage element (e.g. capacitative) or a digital storage element (e.g., SRAM latch). In the case of a digital storage element, a common way to drive pixel storage electrode 106 is via pulse-width-modulation (PWM). In PWM, different gray scale levels are represented by multi-bit words (i.e., binary numbers). The multi-bit words are converted to a series of pulses, whose time-averaged root-mean-square (RMS) voltage corresponds to the analog voltage necessary to attain the desired gray scale value.
For example, in a 4-bit PWM scheme, the frame time (time in which a gray scale value is written to every pixel) is divided into 15 time intervals. During each interval, a signal (high, e.g., 5V or low, e.g., 0V) is asserted on the pixel storage electrode 106. There are, therefore, 16 (0-15) different gray scale values possible, depending on the number of "high" pulses asserted during the frame time. The assertion of 0 high pulses corresponds to a gray scale value of 0 (RMS 0V), whereas the assertion of 15 high pulses corresponds to a gray scale value of 15 (RMS 5V). Intermediate numbers of high pulses correspond to intermediate gray scale levels.
FIG. 2 shows a series of pulses corresponding to the 4-bit gray scale value (1010), where the most significant bit is the far left bit. In this example of binary-weighted pulse-width modulation, the pulses are grouped to correspond to the bits of the binary gray scale value. Specifically, the first group B3 includes 8 intervals (23), and corresponds to the most significant bit of the value (1010). Similarly, group B2 includes 4 intervals (22) corresponding to the next most significant bit, group B1 includes 2 intervals (21) corresponding to the next most significant bit, and group B0 includes 1 interval (20) corresponding to the least significant bit. This grouping reduces the number of pulses required from 15 to 4, one for each bit of the binary gray scale value, with the width of each pulse corresponding to the significance of its associated bit. Thus, for the value (1010), the first pulse B3 (8 intervals wide) is high, the second pulse B2 (4 intervals wide) is low), the third pulse B1 (2 intervals wide) is high, and the last pulse B0 (1 interval wide) is low. This series of pulses results in an RMS voltage that is approximately
      2    3  (10 of 15 intervals) of the full value (5V), or approximately 4.1V.
The resolution of the gray scale can be improved by adding additional bits to the binary gray scale value. For example, if 8 bits are used, the frame time is divided into 255 intervals, providing 256 possible gray scale values. In general, for (n) bits, the frame time is divided into (2n−1) intervals, yielding (2n) possible gray scale values.
Because the liquid crystal cells are susceptible to deterioration due to ionic migration resulting from a DC voltage being applied across them, the above described PWM scheme is modified as shown in FIG. 3. The frame time is divided in half. During the first half, the PWM data is asserted on the pixel storage electrode, while the common electrode is held low. During the second half of the frame time, the complement of the PWM data is asserted on the pixel storage electrode, while the common electrode is held high. This results in a net DC component of 0V, avoiding deterioration of the liquid crystal cell, without changing the RMS voltage across the cell, as is well known to those skilled in the art.
FIG. 4 shows a response curve of an electrically controlled, birefringent liquid crystal cell. The vertical axis 402 indicates the percent of full brightness (i.e., maximum light reflection) of the cell, and the horizontal axis 404 indicates the RMS voltage across the cell. As shown, the minimum brightness (a dark pixel) is achieved at an RMS voltage Vtt. For some wavelengths of light, an RMS voltage less than Vtt results in a pixel that is not completely dark, as shown in FIG. 4. For other wavelengths all RMS voltages less than Vtt result in a dark pixel. In the portion of the curve between Vtt and Vsat, the percent brightness increases as the RMS voltage increases, until 100% full brightness is reached at Vsat. Once the RMS voltage exceeds Vsat, however, the percent brightness decreases as the RMS voltage increases.
FIG. 5 shows an RMS voltage versus gray scale value curve, for an 8-bit (256 gray scale values) gray scale system. The RMS voltage for each gray scale value ("Gray Value") is given by the following formula, where Von is the digital "on" value, typically Vdd:Vrms=√{square root over ((1/255)(GrayValue)(Von)2)}{square root over ((1/255)(GrayValue)(Von)2)}{square root over ((1/255)(GrayValue)(Von)2)}
Gray scale value (x) corresponds to an RMS voltage equal to Vtt and, referring back to FIG. 4, to 0% brightness (i.e., minimum brightness which may not achieve exactly 0 brightness). Thus, the gray scale values less than value (x) are unusable, because for some wavelengths of light, they result in a brighter rather than a darker pixel, and for other wavelengths, the values result in 0% brightness and are, therefore, redundant. Similarly, value (y) corresponds to an RMS voltage equal to Vsat and, referring back to FIG. 4, to 100% full brightness. Thus, the gray scale values greater than value (y) are also unusable, because they result in a darker rather than a brighter pixel. The result of these wasted values is that true 8-bit gray scale resolution is not obtained.
In order to avoid gray scale distortions, all gray scale values must be confined to the useful portion of the liquid crystal response curve (FIG. 4) between Vtt and Vsat. One way to accomplish this is to add an additional bit to the gray scale code (e.g., use a 9-bit gray scale system) and then map the 8-bit values to the values of the 9-bit system corresponding to the useful portion of the response curve. The addition of a single bit, however, increases the bandwidth requirements of the data interface by 100%, and is, therefore, undesirable. What is needed is a system and method for confining all of the available gray scale values to the useful portion of the liquid crystal response curve.
In addition to the problem of confining all of the grayscale values to the useful portion of the liquid crystal response curve, it is also difficult to implement the debiasing (i.e., maintaining a net D.C. bias of 0V across the pixel cells). For example, the voltage being asserted on the common electrode cannot be changed while data is being asserted on the pixel electrodes. To do so, would change the data being asserted on the display (converting high signals to low signals and vice versa) and distort the displayed image. Further, because of the substantial amount of time required to write data to the display, it is difficult to rapidly write an "on" state or an "off" state to the entire display. Additionally, in order to invert the data in the display, the complement of the data must be written to each pixel of the display.
What is needed is a display capable of rapidly inverting the stored data, rapidly implementing on and off states, and providing write time flexibility.


A recording apparatus includes: a first roller; a plurality of second rollers which are displaceably provided between a position that is contacted with the first roller and a position that is left apart from the first roller, and are disposed along an axial direction of rotation of the first roller; and a unit that switches roller position, which causes the second rollers located outside a region of a medium among the plurality of second rollers to leave apart from the first roller depending on a size of a medium that is transported.

1. Technical Field
The present invention relates to a recording apparatus represented by a facsimile, a printer or the like.
2. Related Art
In a recording apparatus represented by a facsimile, a printer or the like, a paper transportation unit that accurately transports recording paper fed from a paper feeding section that feeds the recording paper, as an example of a medium, below a recording head may be configured of a driving roller that is rotated by a driving source and a driven roller that is driven to rotate by pressing the recording paper between the driving roller and the driven roller.
Most of the driving rollers are configured by including a high-friction layer on an outer peripheral surface of a shaft body (for example, a metal shaft) and the high-friction layer is formed of wear-resistant particles and a coating material in which the wear-resistant particles are adhered and held on the outer peripheral surface of the shaft body (for example, see JP-A-2012-121648).
Further, when a paper jam occurs in the middle of a transportation path, when the recording paper is interposed between the driving roller and the driven roller, workability is lowered when removing the recording paper. Thus, a configuration that takes into account the workability of the paper removal and releases (separates) the driven roller from the driving roller is adopted in the related art (for example, see JP-A-2005-112490).
Furthermore, if an object to be recorded is a disk-shaped medium, there is a case where a roller mark is caused by the driven roller coming into contact with the disk-shaped medium. Thus, a recording apparatus disclosed in JP-A-2012-116203 includes a configuration in which each of positions of a plurality of driven rollers is displaced in a contact and separation direction with respect to the driving roller.
The recording apparatus disclosed in JP-A-2012-121648 is made by considering convenience of paper jam recovery work and the recording apparatus disclosed in JP-A-2005-112490 is made by considering the transportation of the disk-shaped medium, however they still have problems as described below.
That is, when recording on the recording paper such as plain paper, a plurality of driven rollers are driven to rotate by coming into contact with the paper and some driving rollers located outside a paper region are driven to rotate by directly coming into contact with the driving roller. However, since the driven rollers of the latter come into contact with the driving roller having the high-friction layer on the outer peripheral surface thereof, that is, the driving roller having a great number of fine unevenness on the outer peripheral surface thereof, as a result, a harsh noise may occur.
Particularly, if the size of the paper is small, since the number of the driven rollers or the contact region coming into contact with the driving roller increases, the degree of the noise becomes more remarkable. Therefore, in recent years, in ink jet printers, noise reduction is further required and it is preferable that occurrence of noise, as described above, be effectively suppressed.