A scanner including a light source, an optical module, a driving device, and a control unit is provided. The light source emits a light beam to the to-be-scanned document. The optical module includes a photo sensing device for receiving the light beam reflected by the to-be-scanned document. The driving device includes a position detecting device, for detecting a position of the optical module relative to the to-be-scanned document, and outputting a position feedback signal accordingly. The control unit includes a light source controller and a timer. The scanning method includes the steps of setting the value of K to 1; moving the optical module to read the Kth scan line and adjusting the luminance of the light source to compensate exposure level of the (K+1)th scan line; and determining if K is smaller than N.

1. Field of the Invention
The invention relates in general to a scanner and method thereof, and more particularly to a scanner with a driving device for feedback control and method thereof.
2. Description of the Related Art
Along with the advance in technology, scanners have become an indispensable image capturing device, while motor is an essential element for driving a photo sensing device to capture images. Direct current (DC) motor with the advantages of small size, low noise, low power consumption and low cost has now been widely adopted in a scanner.
Referring to FIG. 1A, a structural diagram of a DC motor based scanner according to prior arts is shown. Scanner 100 includes a scan flatbed 110, a chassis 120, a DC motor 130 and an application specific integrated circuit (ASIC) 140. The DC motor 130 drives the optical module 120 to move at a constant speed, meanwhile, the photo sensing device (not shown in the diagram) of the chassis 120, a charge coupled device (CCD) for example, captures images of scan lines of a to-be-scanned document 111 on the scan flatbed 110. The DC motor 130 has an encoder 132 for outputting a position feedback signal PF. The ASIC 140, according to the position feedback signal PF, controls the DC motor 130 to precisely position the chassis 120 to assure that the images captured are uniform in quality for each scan line.
However, due to the variation in speed control of the DC motor 130, the exposure time for different scan lines will not be the same. As shown in FIG. 1B, the scanner 100 uses the position feedback signal PF to determine the exposure time T1, T2, T3 of the photo sensing device sensing the to-be-scanned document 111. When the DC motor 130 drives the optical module 120 at a predetermined constant speed, the exposure time for reading a scan line is set to be T1=t2−t0. When the DC motor 130 drives the optical module 120 to sense a certain scan line at a speed higher than the predetermined speed, the exposure time for reading this scan line is set to be T2=t1−t0. When the DC motor 130 drives the optical module 120 to read a certain scan line at a speed lower than the predetermined speed, the exposure time for reading this scan line is set to be T3=t3−t0. For the exposure time T1, T2, T3 for reading different scan lines are not the same, according to the equation that exposure level=light density of the to-be-scanned document 111×responsivity of the photo sensing device ×exposure time×analog front end (AFE) gain, the exposure level for reading each scan line will be different and the quality of the captured image will be affected.
Referring to FIG. 1C, a circuit diagram of a DC motor based scanner disclosed in U.S. Pat. No. 6,037,584 is shown. Considering that the light density of the to-be-scanned document 111 and the spectral response of the photo sensing device are normally set to be constant, the patent adjusts the AFE gain dynamically to compensate the exposure time variation so that each scan line has the same exposure level.
Scanner 150 uses a DC motor 160 to drive an optical module 170 to scan the to-be-scanned document (not shown in the diagram). The DC motor 160 has an encoder 162 for outputting a position feedback signal PF to a timer 182 of an ASIC 180. An exposure control unit 184 controls the exposure time of the CCD 172 in the optical module 170 reading each scan line of the to-be-scanned document according to the position feedback signal PF. Data obtained by the CCD 172 as sensing the to-be-scanned document is output to an analog amplification unit 174 to be amplified. The ASIC 180 of the patent further includes a gain control unit 186, which is controlled by the exposure control unit 184 and the timer 182 to dynamically adjust the AFE gain of the analog amplification unit 174 to compensate exposure level variation of each scan line.
However, the scanner disclosed in above-mentioned patent needs to introduce an additional complicated circuit like the gain control unit 186 to the ASIC 180 in order to dynamically adjust the AFE gain, which makes the system more complicated.


A cleaning device includes a cleaning roll and an intervening member. The cleaning roll contacts the surface of a charge roll that charges a photoconductor, rotates, and cleans the surface of the charge roll. The intervening member is intervened between the charge roll and the cleaning roll and causes the charge roll and the cleaning roll to separate from each other. The intervening member may be spacers that are intervened at both end portions of the charge roll and the cleaning roll and form a gap between the charge roll and the cleaning roll. The intervening member may also be a lubricant.

1. Technical Field
The present invention relates to a cleaning device that cleans a charge roll and an image forming apparatus having the cleaning device.
2. Related Art
A charge roll that charges the surface of a photoconductor directly contacts the photoconductor. For this reason, it is easy for foreign matter remaining on the surface of the photoconductor to adhere to the surface of the charge roll. When foreign matter adheres to the surface of the charge roll, this causes defective charging.
Thus, a cleaning roll made of a sponge is brought into contact with the surface of the charge roll with a predetermined nip pressure, and the cleaning roll is rotated while following the rotation of the charge roll, whereby dirt on the surface of the charge roll is removed.

Cleaning device and image forming apparatus


A color image forming method using a toner image retaining member is disclosed. In the color image forming method, a plurality of electrostatic latent images corresponding to respective color components of an image of a document are formed sequentially on a photoconductive member, and the electrostatic latent images are developed sequentially with respective toners of different colors so as to form the corresponding visible toner images on the photoconductive member. Thereafter, the toner images are transferred sequentially onto the toner image retaining member by electrifying the toner image retaining member every transfer process for each of the toner image so as to form a color image thereon, and the color image is transferred onto a paper.

1. Field of the Invention
The present invention relates to a color image forming method, and more particularly, to a color image forming method with use of a toner image retaining member for retaining a toner image temporarily.
2. Description of the Related Art
A method and apparatus for transferring two toner images on both sides of a copying paper respectively at the same time are disclosed in the Japanese patent publication (JP-B2) No. 54-28740 . In the method and apparatus, a first toner image is formed on a photoconductive body at first and the toner image having been formed is transferred on a toner image retaining member primarily. After the transfer of the first toner image onto the toner image retaining member, a second toner image is formed on the photoconductive body. Furthermore, the first toner image transferred primarily from the photoconductive body onto the toner retaining member and the second toner image formed newly on the photoconductive body are respectively transferred on both sides of a copying paper simultaneously to produce a copy of both sides. However, since an insulator belt is usually used on the toner image retaining member and the toner image formed on the photoconductive body is transferred on the insulator belt by a transfer charger arranged on the back side of the insulator belt, it is difficult to concentrate the action of the transfer charger at the transfer where the photoconductive body and the insulator belt are in contact with each other, and therefore, portions of the photoconductive body no having passed the transfer position receive undesirable affects from the transfer charger. As a result, the toner image may be spoiled.
Also, a transferring image forming method and a transferring image forming apparatus are disclosed in the Japanese patent laid open publication (P-A) No. 56-147166. In the method and apparatus, in order to form a plurality of toner images based on a formed electrostatic latent image, after the toner image formed on a charge retaining drum is transferred on an insulator belt primarily by pressing the charge retaining drum onto the insulator belt, the toner image transferred on the insulator belt is transferred on a copying paper secondarily.
Furthermore, an electrophotographic process of transferring colored electrostatic images is disclosed in the Japanese patent publication (JP-B2) No. 49-209. In the electrophotographic process, after respective colors of toner images formed on a photoconductive body are transferred primarily onto a toner image retaining drum sequentially in multiple processes so as to superimpose the same thereon, the toner image superimposed on the toner image retaining drum is transferred onto a copying paper secondarily. In the specification of the above publication, the primary transfer process for the toner image from the photoconductive body onto the toner image retaining drum is not described concretely.


An optical instrument, such as a spotting scope, is provided. The optical instrument may include a range finder configured to calculate or otherwise determine a distance between the optical instrument and an identified object. The optical instrument may also include a display and a user interface. In some embodiments, an operation system associated with the optical instrument may include sensing touchless gestures. For example, hand gestures or eye gestures may be used to navigate a user interface, to actuate the laser range finder, to alter the brightness of a display, or to carry out any of a number of other operational commands.

Various optical instruments are utilized to view distant objects. For example, spotting scopes, riflescopes, telescopes, binoculars, or other instruments may be used to view various objects at substantial distances. Often, telescopes are used to observe extraterrestrial objects (e.g., planets, stars, galaxies). Other types of devices such as spotting scopes, riflescopes and binoculars, are often used to view terrestrial objects including wildlife, geographical formations, targets during shooting or hunting activities, and a variety of other objects. Many optical instruments provide variable magnifications, making it possible to "zoom" in or out, resulting in the magnification of the viewed image changing to fit the user's preference or need.
Spotting scopes are typically more powerful in terms of magnification than binoculars and may generally be thought of as small, high-powered telescopes having the optics necessary to provide an erect image (i.e., the image will be displayed as it is naturally viewed rather than upside down, as is the case in many telescopes). Often, spotting scopes will have magnification rates between 20× and 60×. Conventional spotting scopes are typically either configured as "straight" scopes, wherein the optical path is generally along a single axis through the objective lens(es) through the eyepiece, or as "angled" scopes, wherein the eyepiece is set at an angle (conventionally at 45 degrees) relative to the optical axis extending through the objective lens(es). Each of these configurations may provide certain advantages, with a primary distinction between the two being the ergonomics of use.
Because of their relatively high power of magnification, spotting scopes are conventional mounted on a tripod or other support structure to provide some stabilization and to reduce image shake when a user is looking through the eyepiece at a magnified image.
A riflescope includes optics that magnify the view of the target and also help to aim the rifle for purposes of accuracy and precision. For example, a riflescope may include a reticle or other aiming point positioned in the field of view that is provided by the optics of the riflescope, the aiming point being aligned with a target by a user prior to firing the rifle. The aiming point may be adjustable so that a shooter may position the aiming point relative to the rifle in order to compensate for one or more factors that affect the travel of a bullet during its flight toward the target.
It is a continual desire within the industry to provide enhanced optics that provide a user with an improved viewing experience, including the viewing of information that may be provided by an associated electronic system in conjunction with the view of a live scene through the optics, as well the user operation of and interaction with the optical device.

Spotting scope with integrated laser rangefinder and related methods


Disclosed is a wave shaping apparatus and a method for shaping an input pulse train signal alternating between a low level and a high level to provide a signal delaying a turn on of one output transistor with respect to a turn off of the other output transistor thus decreasing time, when both the transistors would be simultaneously conducting current.

A person skilled in the art will appreciate that the concepts disclosed herein are applicable to digital integrated circuits (IC), examples of which include, but are not limited to Low Voltage Complementary Metal Oxide Semiconductors (LVCMOS), Low Voltage Transistor-Transistor Logic (LVTTL), High-Speed Transceiver Logic (HSTL), Stub Series Terminated Logic (SSTL), and the like.
One of the challenges in design of output circuitry of digital ICs is satisfying current and voltage requirements dictated by a load connected to the output circuitry, while at the same time achieving a high maximum frequency (Fmax) and low delay of the signal processed by the digital IC. In general, a signal processed by digital ICs comprises a pulse train of a generally variable duty cycle. An ideal pulse train alternates instantaneously between two levels—a low level and a high level, represented by, for example, voltage or current. The up and down transitions between the low level high levels are called the rising edge and the falling edge. The duty cycle, i.e., length of time spent at the low levels and time spent at the high level varies and is determined by the information carried by the signal.
In practice, the instantaneous alternation is never achieved because of physical limitations of the system that generates the waveform. The times taken for the signal to rise from a low level to a high level and back again are called the "rise time" and the "fall time" respectively. The term "rise time" refers to the time required for the signal to change from a specified value of the low level to a specified value of the high level, and the term "fall time" refers to the time required for the signal to change from the specified value of the high level to the specified value of the low level. In other words, the rise time is the time required for the response to rise from x % to y % of its final value. Often the specified values are 10% and 90% of the difference between the high level and the low level.
A conceptual output circuitry 100 as known in the art is illustrated in FIG. 1. A signal to be processed by the output circuitry 100 originates inside of the IC and is conceptually depicted as a signal source 102. In general signal to be processed comprises data. The signal is provided to an input of a pre-driver 104. The task of the pre-driver 104 is to properly condition the signal, i.e., to provide a signal with a proper shape to an output driver 106. The task of the, output driver 106 is to amplify the signal to satisfying current and voltage requirements dictated by a load 108.
FIG. 2 illustrates further details of possible implementation of conceptual block diagram of FIG. 1. By means of example, the topology of the driver 106 of FIG. 1 may comprise a pair of P-Channel MOS transistor 206a and an N-channel MOS transistor 206b as depicted in FIG. 2 When such an output stage is driven by a signal form the pre-driver 204, there is a certain period of time, when both the P-channel MOS transistor 206a, and the N-channel MOS transistor 206b would be simultaneously "ON", i.e., the transistors are simultaneously conducting a current for a certain period of time. Such a current is known as crowbar current (Icrowbar) flowing through both of the transistors. The crowbar current causes voltage change at the power supply VDDS and VSS and power ground nodes (not shown); which in turn causes degradation of the signal.
Because of the finite frequency response of the P-channel MOS transistor 206a and the N-channel MOS transistor 206b decreasing the rise time respectively the fall time of the single signal would not prevent both the P-channel MOS transistor 206a, and the N-channel MOS transistor 206b to be ON for a certain period of time. Furthermore, decreasing the rise time respectively the fall time causes a derivative of current with time (di/dt) to increase. Such increase of di/dt further contributes to voltage change at the power supply and power ground nodes.
An improvement on the single signal solution known in the art modified the pre-driver 104 to comprise a not-AND (NAND) circuit 204a configured so that the falling edge of the NAND voltage signal turns on the P-channel MOS transistor 206a and a not-OR (NOR) circuit 204b configured so that the falling edge of the NOR voltage signal turns on the N-channel MOS transistor 206b. The inclusion of the NAND 204a and NOR 204b circuitry caused the shaping of the signal driving the P-channel MOS transistor 206a and the N-channel MOS transistor 206b to turn on at slightly different times; consequently decreasing the time when both the P-channel MOS transistor 206a, and the N-channel MOS transistor 206b are ON; thus decreasing the di/dt as well as the crowbar current. Such improvement is due to asymmetry between the turn on and turn off times of the NAND 204a and NOR 204b circuits—the falling edge of the output voltage of the NAND circuit 204a is slower than the falling edge of the output voltage of the NOR circuit 204b, while the rising edge of the output voltage of the NAND circuit 204a is faster than the rising edge of the output voltage of the NOR circuit 204b.
As illustrated in FIG. 2, although not always implemented, the pre-driver circuit comprising the NAND 204a and NOR 204b circuitry is provided with the signal to be processed 202 as well as a control signal 201, which enables and disables the at the pre-driver circuit 204 processing of the signal by the output circuitry 200.
However, there is a need in the art for a further improvement in the decrease of the di/dt as well as the crowbar current.

Optimizing pre-driver control for digital integrated circuits


Serviceable laminar flow elements are described. The serviceable laminar flow elements includes a flow sleeve, a laminar flow rod installed within the flow sleeve, a mounting plug arranged at a first end of the flow sleeve configured to fixedly secure the laminar flow rod within the flow sleeve at the first end, and an index cap arranged at a second end of the flow sleeve configured to fixedly secure the laminar flow rod within the flow sleeve at the second end. A laminar flow path is defined by a gap between an interior surface of the flow sleeve and an exterior surface of the laminar flow rod.

The subject matter disclosed herein generally relates to laminar flow elements and systems, and more specifically to serviceable or changeable laminar flow elements and systems that employ serviceable laminar flow elements.
Laminar flow elements have many uses in many diverse industries. For example, laminar flow elements may be employed for processing water in extreme conditions, such as on board spacecraft. Such laminar flow elements may be high precision structures that provide for a fine mixture control of fluids (e.g., gas) in gas-to-water systems or recovery systems. Because of the nature of such recovery systems, high precision is necessary to ensure functionality and efficiency. However, due to the high precision nature of these devices and systems contamination and/or damage may reduce or eliminate the functionality of such devices/systems. Additionally, due to the high precision nature of these devices and systems, performing maintenance and/or repairs may be difficult or impossible (e.g., onboard a spacecraft). Accordingly, it may be advantageous to improve the serviceability of high precision laminar flow elements.


A liquid ink jet ink wherein said ink is non-gelling and comprises a carrier, a pigment and a solid block copolymer of ethylene oxide and propylene oxide having a structure (A) and (B) defined herein.

Ink jet printing is a non-impact method for producing images by the deposition of ink droplets on a substrate (paper, transparent film, fabric, etc.) in response to digital signals. Ink jet printers have found broad applications across markets ranging from industrial labeling to short run printing to desktop document and pictorial imaging. The inks used in ink jet printers are generally classified as either dye-based or pigment-based.
Pigment based inks have been gaining in popularity as a means of addressing these limitations. In pigment-based inks, the colorant exists as discrete particles. The problem is that these inks interact with specially coated image receiving substrates, such as transparent films used for overhead projection and the glossy papers and opaque white films used for high quality graphics, to produce cracked images.
U.S. Pat. No. 5,462,591, by Karandikar et al, discloses an aqueous phase change ink that contains dyes and block copolymers of polyethylene oxide and polypropylene oxides as thermogelling components that causes the ink to gel when its temperature is increased to its thermoinversion point. No pigments are included in these inks.

Ink jet inks containing block copolymers of polyethylene oxide and polypropylene


The present disclosure describes techniques for playing videos. The disclosed techniques include obtaining a total duration and a playing duration of a first video segment; identifying a first video node corresponding to the first video segment and a first directing message associated with the first video node in a video playing plot graph, wherein the video playing plot graph is pre-generated and comprises a plurality of video nodes, and each video node corresponds to a video segment and is associated with a directing message comprising information related to a second video node; determining the second video node based on the first directing message in response to a determination that a difference between the total duration and the playing duration is equal to a predetermined amount; obtaining the second video segment based on the second video node; and playing the second video segment continuously once the first video segment is finished.

Existing video websites can divide a complete video file, such as a movie, into several video segments and store them in a video resource library of a video website. Each of the divided video segments can also be identified as different video types according to different video contents, such as funny type videos, music type videos, love type videos and so on. However, existing video websites are generally only able to provide the video segments for the user to play separately.

Method and device of playing video, and computing device


A power amplifier for use in a mobile handset includes an amplifying transistor, a bias circuit including a bias transistor, the bias circuit providing a bias current to bias the amplifying transistor, and a bias current control circuit, responsive to fluctuation in a reference voltage and variation in temperature, for adjusting the bias current to control an operation current of the amplifying transistor.

As is well known, modern wireless communication devices, such as mobile handset including a CDMA cell phone, are held to ever-higher performance standards. Transmissions must be clear and undistorted, and the battery in the devices must be small and have a long life. In order to meet these consumer requirements, wireless telephone designers have moved away from using traditional silicon-BASED bipolar transistors as power amplifiers and toward using more exotic transistors, such as heterojunction bipolar transistors (HBTs). Such HBTs provide outstanding power efficiency and high linearity, thus making CDMA cell phone achieve longer battery life and better signal characteristics for voice and data.
Of course, an HBT like a bipolar junction transistor (BJT) requires a direct-current (DC) bias signal to be applied to its input terminal to establish its operating point. The operating point of a transistor may be defined as a point on a transistor's characteristic curve at which the transistor will operate in the absence of an input signal. Since changes in the DC bias signal affect the operating point of the HBT and thus adversely affect the linearity of the amplifier, the DC bias signal must be very stable and unaffected by variations in temperature or in a reference voltage Vref.
FIG. 1 illustrates a conventional power amplifier module 100 for use in a CDMA cell phone. The power amplifier module 100 includes a conventional temperature compensated bias circuit in addition to an amplifying circuit. The amplifying circuit includes an amplifying transistor Q1 having an emitter grounded; an inductor L, one end thereof being supplied with Vcc and the other end thereof being connected to a collector of Q1; an output capacitor Co disposed between the collector of Q1 and an RF_OUT terminal; and an input capacitor Ci coupled between an RF_IN terminal and a base of Q1.
The bias circuit includes a bias transistor Q2, a collector thereof being supplied with Vcc; a diode-connected transistor D1 (i.e., a bipolar transistor with short-circuited collector and base), an anode thereof being connected to a base of Q2; an additional diode-connected transistor D2, an anode thereof being connected to a cathode of D1 and a cathode thereof being grounded; and a resistor R1, one end thereof being supplied with the reference voltage Vref and the other end thereof being connected to the anode of D1.
Referring to FIG. 1, the bias circuit is used to set an operating current for the power amplifier Q1. A reference current Iref flowing from the reference voltage Vref to a circuit ground through the resistor R1 and the diode-connected transistors D1 and D2 is mirrored as a collector current Ic through the power amplifier Q1 between the supply voltage Vcc and ground. The diode-connected transistors D1 and D2 provide a compensating effect that can protect the power amplifiers Q1 and Q2 against thermal runaway due to a temperature increase thereof.
Once the reference voltage Vref is set to have a predetermined value, a bias current IB of Q1, i.e., a DC component of a base current of Q1 is fixed. That is to say, the bias circuit supplies a constant bias current regardless of the output power, which in turn gives rise to a constant quiescent current IC (i.e., a DC component of the collector current of Q1), IC being an operation current of Q1.
However, the conventional power amplifier module 100 described above is highly sensitive to variation in the reference voltage Vref. For example, if the reference voltage Vref increases, a current at the base of the transistor Q2 and subsequently a current at the emitter thereof also increase. As a result, the amount of current IB flowing into the base of transistor Q1 correspondingly increases. Inversely, if the Vref decreases, a current at the base of the transistor Q2 and subsequently a current at the emitter thereof also decrease and thus the amount of the bias current IB correspondingly decreases.
Therefore, the conventional power amplifier module 100 has drawback due to the fluctuations in the reference voltage that substantially makes the operation current Ic of the transistor Q1 fluctuate.
On the other hand, as temperature rises, respective turn-on voltages (VBE1 and VBE2) of transistors Q1 and Q2 are reduced. If the VBE1 and VBE2 are lowered, voltage VA at node A is lowered and thus a reference current Iref increases. An increment ΔIref of the reference current Iref is divided into the diode-connected transistors D1 and D2 and the transistors Q1 and Q2 at node A. As a result, a base current of the transistor Q1 increases by a portion of the increment ΔIref to thereby increase the bias current IB.
On the contrary, as temperature is lowered, respective turn-on voltages (VBE1 and VBE2) of transistors Q1 and Q2 are increased. If the VBE1 and VBE2 are increased, the voltage VA at node A is increased and thus the reference current Iref is reduced. A decrement ΔIref of the reference current Iref is divided into the diode-connected transistors D1 and D2 and the transistors Q1 and Q2 at node VA. As a result, the base current of the transistor Q1 decreases by a portion of the decrement ΔIref to thereby reduce the bias current IB.
As described above, the conventional power amplifier module 100 compensates a portion of the increment or the decrement in the bias current IB due to the variations in temperature, but the compensation result is not so much.

Bias circuit for providing a constant bias current to a power amplifier

Information and Communications University Educational Foundation


Some embodiments include semiconductor constructions having an active region surrounded by insulating material. A groove crosses the active region to divide the active region into first and second portions. A conductive wordline material is within the groove. First and second diffusion regions are within the first portion of the active region, and vertically arranged to sandwich a part of the first portion therebetween. Third and fourth diffusion regions are within the second portion of the active region, and are vertically arranged to sandwich a part of the second portion therebetween. First and second conductive regions are in electrical contact with the first and second diffusion regions, respectively. Third and fourth conductive regions are in an electrical contact with the third and fourth diffusion regions, respectively.

Pillar-type transistors (vertical transistors) may have desirability in terms of size and scalability. In such pillar-type transistors, diffusion layers comprising sources and drains are formed at upper and lower portions of pillars, and channels are formed between the sources and the drains within the pillars. Bitlines may be disposed on lower portions of pillar-type transistors for utilization in memory (e.g., dynamic random access memory (DRAM)).
There is a continuing goal to improve architectural layouts of integrated circuit structures in an effort to maintain acceptable electrical connections between components while achieving ever higher levels of integration. It is desired to improve architectural characteristics of pillar-type transistors.

Semiconductor constructions having grooves dividing active regions


In an improved quick disconnect coupling comprised of operator-actuated coupler and nipple assemblies, the former including an actuating sleeve, with the coupled assemblies having first and second sealing assemblies respectively, wherein the improvement comprises, in combination, that each of the sealing assemblies includes, in addition to the known torodial sealing element, a first non-continuous metallic backup ring and a second non-metallic backup ring interposed between the torodial sealing element and the first backup ring, both backup rings being of generally truncated triangular shape, in cross section; and a metallic insulating sleeve, surrounding the actuating sleeve while being substantially fully radially spaced therefrom, via a peripheral air gap, except for a band portion at one end thereof, this band being interference-fitted on a corresponding portion of the actuating sleeve and including a plurality of axially-extending, spaced, scalloped recesses defining an additional insulating air space and having spaced boundaries that provide surfaces for the interference-fitting.

A hydraulic system QDC (Quick Disconnect Coupling), comprised of operatively connected nipple and coupler assemblies, provides for ease of maintenance when servicing an aircraft or a vehicle. Such QDCs permit the removal/replacement of associated equipment with minimal or preferably no loss of hydraulic fluid.
Existing, commercially available, Thread-Lok QDCs provide today's aerospace and other critical fluid handling systems with quick disconnect capabilities, self-sealing action and visual/touch indication of fully coupled positions. Such Thread-Lok couplings offer simple one hand operation as well as reliable performance during the maintenance of fluid handling systems. These thread-together couplings provide the mechanical advantage required for coupling under higher pressures.
One of the more difficult challenges that QDC manufacturers face today is the ever increasing demand for such couplings to be resistant to onboard fire during flight or operation. Existing industry specifications, including AS 1055, establish test criteria for couplings to be fire resistant and even fire proof. During a fire resistance test, the QDC is exposed to flame temperatures of over 2000 degrees F. and must be able to contain leakage satisfactorily at the coupling's normal internal pressure and flow rate for a minimum of five minutes. In order to be considered fire proof, a QDC must pass the same test conditions, but for a minimum of fifteen minutes. A key parameter for such couplings to pass this test is the ability of the internal fluid flow to carry away the heat generated and subsequently transferred by the flames. Today, many end users are now even requesting QDCs that can pass this test at normal operating pressures without the benefit of any internal fluid flow.
The noted problem has been addressed in the prior art and a fire resistant sealing ring combination is set forth in U.S. Pat. No. 3,869,132 to Taylor et al., and involves the use of a metallic static seal "C" ring. While the concept of the use of an elastomeric seal for providing the main sealing feature under normal operation and the use of a metal seal during a fire is similar to the QDC of the present invention, the present invention involves the use of a radial type seal, unlike that of this reference which involves the use of a face seal design. The metal "C" ring and other variations set forth in this reference require substantial force for actuation and cannot be readily adapted for use in quick disconnect applications since this type of metal seal requires not only substantial force to operate but also has a narrow functional scope.
U.S. Pat. No. 4,269,389 to Ekman, while pertaining to a quick disconnect device, uses sealing philosophies that are vastly different from those of the present invention. Similarly, while the structure set forth in U.S. Pat. No. 5,845,945 to Carstensen, in FIG. 3, pertains to a metal wedge back-up ring seal and an O-ring similar to that of the present invention, the concept is used in this reference is used in a single connection application mechanism that allows the connection of two tubes and does not contain a feature for the removal of the two tubes as is typical in a QDC and thus represents a totally different application. The noted arrangement of the seal and back-up ring is solely to eliminate the gap between the tapered female member and the tapered male member due to tolerances and thus functions only to provide sealing but does not include a fire resistant function.
While the structure of U.S. Pat. No. 6,173,968B1 to Nelson et al. includes a metal wedge back-up seal an O-ring arrangement similar to that of the present invention, the back-up ring has only one wedge angle that causes the back-up ring to block the extrusion gap formed between the male and female members. In contrast, the present invention seal ring utilizes two angles, with the additional angle allowing for increased force between the two parts and also includes a secondary back-up seal ring of a high strength and high temperature-resistant material. The noted reference design only operates up to about 500 degrees F. as compared with that of the present invention which has to operate in fire environments that have temperatures as high as 2250 degrees F. A key feature in this reference is that it utilizes a relatively large extrusion gap whereas in the present invention the extrusion gap is deliberately kept small.
The structure set forth in WO 89/01586 to Millard is again intended for connecting together two pipes. The noted coupling is unlike a standard QDC that can be coupled without requiring any tools. This reference requires the parts to be bolted together and the seal design is different from that of the present invention. Similarly, the structure of U.S. Pat. No. 3,612,577 to Pope et al., involves concentric pipes that uses multiple static seals with supporting back-up rings. This differs from the present invention in that the reference structure does not provide a coupling function. The only item of relevance is that the metal back-up ring has the form of a wedge. However, this back-up ring is welded in place whereas the back-up ring of the present invention is free floating and is designed to slide and move to its actuation position, when pressurized. Finally, UK patent application GB 2175355A appears to pertain to an oil well structure for creating a seal. While a wedge is added to the structure to prevent extrusion of the seal as the parts are pressed together it includes no similar features with respect to those of the present invention.
Turning now to heat shield assemblies, U.S. Pat. No. 5,761,907 to Pelletier, et al., also assigned to the assignee of the present invention, pertains to a thermal gradient dispersing heat shield assembly and the metal insulating sleeve thereof serves a similar function to heat shield utilized in the present invention. However, this reference patent pertains to non-analogous art, namely by being used in a fuel nozzle used to inject fuel in a jet engine. This reference seems to suggest that this is an incremental improvement to a prior art structure that also contains a heat shielding structure. Air gaps are, in fact, included in many aerospace and non-aerospace parts to serve as thermal barriers. The insulating sleeve of the present invention works in combination with other components in the QDC to block both radiation and convective heat transfer that promotes the breakdown of the seals that leads to QDC failure. The two noted applications are vastly different, with the insulation characteristics being the only somewhat similar feature. Similarly, the structure in U.S. Pat. No. 6,149,075 to Moertle et al. pertains to a method and apparatus for shielding heat from a fuel nozzle stem, in a non-analogous art, and provides a complete void for reducing heat transfer. As already noted, the insulation sleeve in the present invention works in conjunction with other parts in the QDC to block radiation and convection heat from causing heat leaks.
None of the discussed prior art structures pertains to the combination of features used in the present invention to achieve the requirements set forth in the noted industry standards.

Zero flow fireproof quick disconnect coupling


A power system includes an output voltage terminal that is coupled by a first conductor to one pressed power contact which is then coupled by a second conductor to an electronic device. Also, the electronic device is coupled by a third conductor to one pressed signal contact which is then coupled by a fourth conductor to an output voltage feedback terminal on the power supply. Further, the power system includes a fault detection circuit which is coupled to the fourth conductor. In operation, the fault detection circuit senses if the pressed signal contact is open at a time when the pressed signal contact is supposed to be closed. If an open contact is sensed, the fault detection circuit sends a signal to an operator which indicates that corrective action is needed.

This invention relates to systems which deliver electrical power to a subassembly of electronic devices, such as a subassembly of one or more integrated circuit chips on a printed circuit board, thru pressed electrical contacts. Each such contact includes two mating terminals that get pressed together.
In a conventional printed circuit board of the prior art, electrical power is received thru a connector that is attached to one edge of the board. Typically, the connector has several cylindrical-shaped pins that slide into corresponding holes of a socket which is mounted to a backplane. Electrical power from a power supply travels along conductors in the backplane to the socket, and then travels through the pins and along conductors on the printed circuit board to the electronic devices.
However, a problem with the above conventional practice is that the conductors which couple the electronic devices on the printed circuit board to the power supply inherently have a parasitic capacitance, a parasitic inductance, and a parasitic resistance. Those parasitic parameters limit the ability of the power supply to keep the voltage constant at the electronic devices.
One way to reduce the above parasitic parameters is to shorten the conductors which couple the electronic devices to the power supply. This can be achieved by mounting the power supply on a second printed circuit board which is held parallel to the printed circuit board that holds the electronic devices; providing mating electrical terminals on two surfaces of the printed circuit boards that face each other; and pressing mating terminals together.
But, if the above two printed circuit boards somehow get misaligned, the open circuits or abnormally high resistances can occur between the mating terminals. In that case, the power supply will again be unable to properly deliver power to the electronic devices.
Accordingly, a primary object of the present invention is to overcome the above problem.
A power system, which constitutes one preferred embodiment of the present invention, includes a power supply that has an output voltage terminal and an output voltage feedback terminal. The output voltage terminal is coupled by a first conductor to one pressed power contact which is then coupled by a second conductor to an electronic device. Also, the electronic device is coupled by a third conductor to one pressed signal contact which is then coupled by a fourth conductor to the output voltage feedback terminal on the power supply.
Further, and in accordance with the present invention, the power system includes a fault detection circuit which is coupled to the fourth conductor. In operation, the fault detection circuit senses if the pressed signal contact is open at a time when the pressed signal contact is supposed to be closed. If an open contact is sensed, the fault detection circuit sends a signal to an operator which indicates that corrective action is needed.
Preferably, the power supply and the fault detection circuit are mounted on a first printed circuit board; the electronic device is mounted on a second printed circuit board; and the pressed power contact as well as the pressed signal contact lie on two surfaces that face each other on the first and second printed circuit boards. This structure enables the power supply to be very close to the electronic device; and that enables the first, second, third and fourth conductors to be short. Thus, the parasitic capacitance, parasitic inductance and parasitic resistance of those conductors will be small; and in addition, any open circuit fault in the pressed signal contact will be detected.

Power system having pressed electrical contacts and which detects faults in the contacts


A transfer system for a composite material including: a nonwoven as carrier material and a textile layer of reinforcing fibers, wherein the reinforcing fibers consist of mono- or multifilaments or tapes and the carrier material is adhesively bonded to the layer of reinforcing fibers.

Nonwovens are frequently employed to improve the properties of area-measured/sheet materials. They improve, for example, the breaking and tearing resistance, prevent the propagation of cracks, increase impact strength and enhance the visual appearance. The open porosity of the nonwovens has a positive effect on the permeation of the binding agents contained in the composite.
Reinforcing fibers are used in packaging materials and engineered products to increase tensile strength, impact strength, stiffness and processing compatibility. In combination with nonwoven fabrics, improvements are achieved that result from the combination of the properties of both materials. A composite of polyester films and reinforcing fibers has proven itself for sports sailing purposes.
So-called scrims are also employed to enhance the roughness and grip of surfaces. For example, scrims are applied to the surface of surfboards with a view to improving grip/skid resistance.
As a rule, fiber reinforcements are applied to area-measured/sheet material directly during production by mechanically inserting the respective fibers into an adhesive bed. The incorporation of a fiber reinforcement into an adhesive bed is usually associated with inaccuracies that do not serve the intended purpose, which is, for example, to absorb the tensile forces arising in a sail. In this case, it would be desirable to be able to introduce a fiber reinforcement into the area-measured/sheet material with precise alignment and in a tight form.
A latticework made of several adhesively bonded fiber layers is known from the publication WO 2013/148696 A1, said latticework being usable for the modification of surfaces. The production is rather sophisticated and the adhesion of the different fiber layers with each other is limited.
Therefore, there is a need for systems by means of which a latticework of reinforcing fibers can simply be produced in a form conducive to application and transferred to a surface. Such a system shall in particular ensure that the application of the reinforcing fibers can be carried out precisely, i.e. without distortion and in a tight form, and results in a permanent fixation of said fibers. The system should be applicable and adaptable to a plurality of different kind of surfaces.

Transfer system for a composite material


A belt type continuously variable transmission includes an adjustable sheave which is provided with a fixed rotor fixed to a revolving shaft and with a movable rotor attached to the revolving shaft by spline fit in a manner inhibiting their relative rotation and allowing axial displacement so that a groove width is adjustable between the movable rotor and the fixed rotor, wherein the revolving shaft is provided with a load supporting portion on which tip surfaces of spline teeth of the movable rotor are in slide contact, whereby a radial load from the movable rotor is supported by the load supporting portion.

1. Field of the Invention
The present invention relates to a belt type continuously variable transmission for transmitting the revolution of an input shaft to an output shaft by changing the revolution ratio steplessly and, in particular, to the structure of a movable rotor for supporting a radial load and of a revolving shaft onto which the movable rotor is fit in a manner inhibiting their relative rotation and allowing axial displacement.
2. Description of Related Art
A belt type continuously variable transmission for vehicles comprises: a pair of revolving shafts mutually in parallel; a primary-side sheave (input-side pulley) supported in a revolvable manner by the revolving shaft on the input side and having an adjustable groove width; a secondary-side sheave (output-side pulley) identically supported in a revolvable manner by the revolving shaft on the output side and having an adjustable groove width; and a drive belt wound around the primary-side sheave and the secondary-side sheave constituting the above-mentioned pair, whereby the effective diameter of the primary-side sheave and the effective diameter of the secondary-side sheave are varied so that the revolution ratio is varied steplessly.
For example, each of the above-mentioned sheaves comprises: a fixed rotor fixed to the revolving shaft in a manner inhibiting their relative displacement; and a movable rotor fit onto the revolving shaft in a manner inhibiting their relative rotation and allowing relative axial displacement, whereby when the movable rotor is moved in an axial direction so that the distance to the fixed rotor is varied, then the groove width is varied so that the wind-around diameter, that is, the effective diameter, of the drive belt is varied.
In the connection (linkage) between the above-mentioned movable rotor and the revolving shaft, ball splines are used in general. Nevertheless, such a fit structure via ball splines results in a high cost. Thus, methods have been proposed for fitting a movable rotor onto a revolving shaft in a manner inhibiting their relative rotation and allowing relative axial displacement without the use of ball splines. An example is given in Japanese Published Unexamined Patent Application No. H6-341500.

Belt type continuously variable transmission


In a system and method for enabling a person to be transported in a personal transport vehicle, the vehicle includes smoothly operable controls and a safety user-positioning strip. The vehicle further includes a power source rapid disconnection and connection system for recharge and replacement and for secure connection. Also, the vehicle may include a safety speed regulator, and a bi-directional safety braking system. Further, the vehicle includes a preferential drive sharp-turns enabling system. The vehicle further includes an initially-flat indicia-applicable cowling. It may also include a protective security lock, a further or alternative braking system, and a trailer for enabling the carrying of items, and may be readily separable for shipping.

1. Field of the Invention
This invention is generally related to vehicles, and more particularly, to a personal transport vehicle for enabling a person to be effectively transported thereby.
2. General Background and State of the Art
It is known to enable a person to be transported by a personal motorized vehicle such as a two-wheel motorized scooter or a motorized bicycle.
However, it would be desirable to provide a personal transport vehicle which would enable a person to operate the vehicle in an efficient and effective manner. It would further be desirable to require the person to be safely positioned in the vehicle before the vehicle is operable. It would still further be desirable to enable the vehicle to be operable to provide smooth movement and to prevent jerky movement thereof. Moreover, it would be desirable to enable rapid replacement and ensure secure connection of the power source for the vehicle for enabling continuing operation of the vehicle.
It would also be desirable to enable safety regulation of the speed of the vehicle in areas of vehicle operation. Still further, it would be desirable to enable safe braking of the vehicle in the forward or reverse direction of movement thereof. Also, it would be desirable to enable making sharp turns with the vehicle when desired or required. Moreover, it would be desirable to enable the application of indicia on the vehicle for specific identifying purposes, and to enable the vehicle to be securely lockable to prevent theft thereof. Furthermore, it would be desirable to enable the vehicle to be manufactured in readily separable sub-assemblies to enable efficient shipping thereof, to provide a different type of braking system for safety purposes, and to enable the person to transport additional items as desired or needed.
Therefore, there has been identified a continuing need to provide a personal transport vehicle for enabling a person to be transported in an effective and efficient manner.

Personal transport vehicle system and method


The present disclosure provides a power control method and a power control apparatus for uplink channels. The power control method includes steps of: determining, by a UE, target transmission powers for the uplink channels in each carrier group, the UE being configured with at least two carrier groups, UCI in each carrier group being fed back via PUCCH(s) and/or PUSCH(s) on at least one uplink carrier corresponding to the carrier group; determining, by the UE, whether or not a sum of the target transmission powers for the simultaneous transmission uplink channels exceeds an allowable maximum transmission power of the UE; and in the case that the sum of the target transmission powers for the simultaneous transmission uplink channels exceeds the allowable maximum transmission power of the UE, reducing, by the UE, powers for the PUCCH(s) and/or PUSCH(s) carrying the UCI of different carrier groups among the simultaneous transmission uplink channels at least in accordance with priorities of types of the UCI, so that a sum of the transmission powers for all the uplink channels in a current uplink subframe does not exceed the allowable maximum transmission power of the UE. According to the present disclosure, it is able to perform uplink power control in the case that the UE supports the independent UCI feedback for different carrier groups.

A Long Term Evolution-Advanced (LTE-A) system may support a transmission method for performing Uplink Control Information (UCI) feedback on the basis of carrier groups, i.e., dividing aggregation carriers into a plurality of carrier groups and performing the UCI feedback within each carrier group. An uplink carrier is designated in each carrier group, so as to feed back the UCI of the carrier group on the uplink carrier via a Physical Uplink Control Channel (PUCCH). Also, the UCI corresponding to the carriers in each carrier group may be fed back on a Physical Uplink Shared Channel (PUSCH) for the carrier group. Hence, for a User Equipment (UE), there may exist in an identical uplink subframe a plurality of PUCCH(s) and/or PUSCH(s) carrying the UCI for different carrier groups.
The UCI may include Acknowledgement/Non-Acknowledgement (ACK/NACK), Chanel State Information (CSI) and Scheduling Request (SR), and the CSI may include periodic CSI and aperiodic CSI.
LTE-A Release-10 (Rel-10) and Release-11 (Rel-11) systems merely support the PUCCH transmission on an uplink Primary Component Carrier (PCC). For the UE, the PUSCH transmission may exist in an identical uplink subframe on a plurality of uplink carriers simultaneously, but the UCI transmission may be carried by merely one of the PUSCH(s). In the case of the co-existence of the PUCCH(s) and the PUSCH(s) carrying the UCI, the UCI carried by the PUCCH(s) and the PUSCH(s) is of different types. For example, the PUCCH may carry the ACK/NACK, while the PUSCH carries the periodic CSI. In other words, the UCI carried by the PUCCH(s) is of a more important type, and there will not exist such a situation where the UCI of an identical type is carried simultaneously by the PUCCH(s) and/or PUSCH(s) or the UCI carried by the PUSCH(s) is of a more important type. Hence, during the power control, it is required to preferentially ensure that the transmission power for the PUCCH(s) is not reduced.
In the LTE-A system, there is the data transmission simultaneously over the PUCCH(s) and/or PUSCH(s) carrying the UCI, and it is not defined in the original system about how to reduce the power for the PUCCH(s) and/or PUSCH(s) carrying the UCI in the case of constrained power. In addition, the PUCCH(s) and/or PUSCH(s) may carry the UCI of an identical type or different types, e.g., they may carry the ACK/NACK, or one of the PUCCH(s) (or PUSCH(s)) may carry the periodic CSI for one carrier group while another one of the PUCCH(s) (or PUSCH(s)) may carry the ACK/NACK for another carrier group. In the case that the power is constrained but a power control scheme for the original system is still used, i.e., the transmission power for the PUCCH(s) is preferentially granted, the transmission of the UCI of an important type, e.g., the SR or the ACK/NACK may be adversely affected due to the reduction in the transmission power, and thereby the entire transmission performance for the system will be adversely affected.
In a word, there is currently no uplink power control scheme in the case that the UE supports the independent UCI feedback for different carrier groups.

Power control method and power control apparatus for uplink channels

CHINA ACADEMY OF TELECOMMUNICATIONS TECHNOLOGY


An animal surgery table having an electrical heating pad disposed immediately beneath the operating surface and thermostatically controlled by a temperature sensor embedded within the heating pad for preventing heat loss from animals during surgery is disclosed.

1. Field of the Invention
This invention relates to heated animal surgery tables.
2. Description of the Related Art
Animal surgery tables are well known in the prior art. The upper, or supporting surface, of animal surgery tables is typically stainless steel, which can be cleaned and sterilized easier than most surfaces. Accordingly, they are well suited to use during surgery.
Although widely used, such tables present a significant problem in use. Stainless steel is a good conductor of heat and consequently draws body heat out of the animal during surgery. Studies demonstrate that the resulting heat loss typically drops the animal's body temperature by about 2.degree. F. (1.11.degree. C.). When an animal's body temperature drops, its heart rate increases, increasing the loss of blood and the general stress on the animal. This thermal loss can result in hypothermia, increases the trauma and stress on the animal, increases the mortality rate from surgery and from certain types of illness or injury, increases recovery time and reduces metabolism.
Rags are sometimes wrapped around the animal to reduce the heat loss, but the practice is largely ineffective for this purpose. The practice is also unsanitary and can interfar with the surgery.
Accordingly, there is a need for an animal surgery table that does not draw heat away from the animal during surgery.


The disclosure relates to a superhydrophobic surface. Methods of fabrication are disclosed including laminating an optically transparent polymer sheet with hydrophobic nanoparticles such that the nanoparticles are partially embedded and partially exposed. The resulting assembly remains optically transparent. Additional methods include the lamination of nanoparticles to flexible fabrics and the production of molded articles using nanoparticle-treated molds.

Superhydrophobic surfaces having a water contact angle greater than 150° and a water slip-off angle less than 10° can have many potential applications, such as from small non-wetting micro/nanoelectronics to large self-cleaning industrial equipment.
Numerous methods and materials have been developed to fabricate superhydrophobic surfaces. For practical applications, such surfaces should exhibit mechanical and chemical stability as well as abrasion resistance. For example, if a superhydrophobic surface is touched by a bare hand, the touched area of the surface could be contaminated by salt and oil and therefore could have an increased surface energy, which reduces the surface hydrophobicity. In addition, the force exerted by touching could damage the fragile rough structure of the surface, which could result in permanent loss of its superhydrophobicity. However, despite ongoing efforts, most reported artificial superhydrophobic surfaces suffer from poor mechanical and/or chemical stability.
In addition to mechanical and/or chemical stability, a commercially viable superhydrophobic surface should exhibit a reliable resistance to water pressure. In practice, a static pressure could be generated by immersing a hydrophobic surface under water and a dynamic pressure could be generated by applying water droplets or water streams onto a hydrophobic surface. Recent research shows that even a lotus leaf can be wetted within one hour after immersed under water at a depth of 0.55 m (i.e., under a water pressure of about 0.78 psi).

Flexible fabric having superhydrophobic surface

Research Foundation of the City University of New York


Boost switching power conversion involves an apparatus for controlling transfer of power from an input voltage source to an output voltage sink. The apparatus includes a switch for controllably permitting or inhibiting delivery of current from the source to the output sink when the switch is off or on, respectively. Circuit elements of the apparatus define a characteristic time scale for time variation of the flow of current in the switch after the switch is turned on, and a switch controller is provided for turning the switch on and off at times when the current in the switch is zero. The rate at which the switch is turned on is controlled to regulate the ratio of the voltage across the output voltage sink to the average value of voltage across the input source such that the ratio is greater than or equal to one. A uni-directional conducting device is provided to permit current flow to the voltage sink after the switch has opened and to prevent reverse current flow from the voltage sink back toward the input source.

This invention relates to boost switching power converters.
Boost switching power converters accept power from an input voltage source and deliver power to a load at a controllable load voltage value which is greater than the voltage delivered by the input source. Such converters are useful in applications where a load must be supplied with a voltage greater in magnitude than the available source voltage, or where the magnitude of the voltage delivered by an input source may, under either steady-state or transient conditions, drop below the minimum value of operating voltage required by the load. In one increasingly important application, a boost switching converter forms the core element of a power factor correcting AC to DC preregulator. In such preregulators, an AC voltage source is rectified and delivered to the input of a boost switching power converter. The boost switching power converter is controlled so as to maintain the load voltage at or above both the peak value of the AC source voltage and the minimum operating voltage of the load, while simultaneously forcing the boost converter input current to follow the time varying periodic waveform of the AC source. In this way, the voltage delivered by the boost switching converter is controlled to be within the operating voltage range of the load, while the power factor presented to the AC source is kept at essentially unity. Examples of preregulators of this type are described in Wilkerson, U.S. Pat. No. 4,677,366, Williams, U.S. Pat. No. 4,940,929, and Vinciarelli, U.S. patent application Ser. No. 07/642,232, filed Jan. 16, 1991. One such prior art boost switching converter is shown in FIG. 1. In the Figure, an input inductor 12 is connected in series with an input voltage source 14, of magnitude Vin, and a switch 16. A diode 18, connected between the junction of the input inductor and the switch, is poled to carry current towards an output capacitor 20 and a load 22. In operation, the frequency at which the switch 16 is turned on and off during a converter operating cycle is fixed, and the duty cycle of the switch (i.e., the fraction, D, of the time that the switch is on during an operating cycle) is varied as a means of controlling the converter output voltage, Vo. The inductor smooths the input current, I1, keeping it essentially constant throughout the operating cycle, and the output capacitor smooths the effect of variations in the current Io so that the converter delivers an essentially DC output voltage. When the switch is on, the voltage across the switch is zero (assuming ideal circuit elements) and all of the input current flows losslessly in the switch; when the switch is off all of the input current flows through the diode toward the capacitor and the load and the voltage across the switch is equal to the output voltage Vo. Under steady state conditions, the average voltage across the input inductor must be zero, else the average value, Iin, of the input current, I1, will vary. Thus, the average value of the voltage across the switch, (1-D).multidot.Vo, must equal Vin, hence Vo=Vin/(1-D). Since D must be between zero and one, Vo>Vin. In prior art boost switching converters of the kind illustrated in FIG. 1, neither the switch nor the diode is ideal, and both elements contribute to converter losses. When the switch is turned on it is exposed to both the current flowing in the input inductor and to a reverse current which flows from the output capacitor back through the diode during the diode reverse recovery time. Switch turn-off occurs when the switch is carrying the full converter input current. Since both the rise and fall time of the switch are finite, the presence of switch voltage and current during the switch transition times will cause power to be dissipated in the switch, and, all other conditions being equal, these switching losses will increase directly with converter operating frequency. Thus, although increased operating frequency is desirable in that it allows reducing the size of the input inductor and the output capacitor (and hence the size of the converter), prior art converters inherently must trade power density against operating efficiency. As a practical matter, as the operating frequency of a prior art boost switching power converter is raised much beyond 100 KHz, efficiency declines rapidly and the thermal and electrical stresses on the switch become unmanageable. Another characteristic of prior art boost switching converters is that two or more units connected to a common input source and load will not inherently share load power if operated synchronously. Current sharing between units connected in this way is first-order dependent on second-order effects (e.g., diode voltage drops, switch impedance).


A close spaced planar vacuum diode is constructed with a photoemissive first electrode and a low work function second electrode. As a result of photon flux on said photoemissive first electrode, electrons are emitted into the vacuum space and travel to said second electrode. This electron current may then flow through an external load, powering said external load.

Field of Invention
This invention relates to the generation of electricity using photoemission and photoemission-thermionic hybrid generators.
Photovoltaic Solar Cells
The first practical solar cell was developed at Bell Laboratories in 1954 (U.S. Pat. No. 2,780,765). With the advent of the space program, photovoltaic cells made from semiconductor-grade silicon quickly became the power source of choice for use on satellites. Disruption of oil supplies to the industrialized world in the early 1970's led to serious consideration of photovoltaic cells as a terrestrial power source, focusing research attention on improving performance, lowering costs and increasing reliability. These three issues remain important today even though researchers have made extraordinary progress over the years.
For photovoltaic cells to be widely used, the costs must be competitive with those of conventional forms of electricity, which are typically 6-7 cents per kilowatt-hour. The US Department of Energy chose a target of 6 cents per kilowatt-hour for its terrestrial photovoltaic program (National Renewable Energy Laboratory. Photovoltaics Program Plan, FY 1991-FY 1995 (1991) National Photovoltaics Program, U.S. Dept. of Energy, Washington, D.C.). Today photovoltaics generate electricity at 20-30 cents per kilowatt hour; an improvement by a factor of five is therefore needed to compete in the bulk electricity market. A number of components influence photovoltaic energy costs. Foremost are the module efficiency, cost per unit area, and lifetime.
The maximum theoretical efficiency for a variety of semiconductor materials can be calculated and is in the 30-35% range, depending on the material. The highest-efficiency single-junction solar cells are made from crystalline silicon and GaAs. Silicon cells of 23% efficiency and GaAs cells of 25% efficiency have been reported. The efficiency of polycrystalline silicon is approximately 18%. A feature of photovoltaic cells is the need to draw current by way of metal contacts distributed over the negative and positive faces of the cell. This creates a problem for cell efficiencies because the contacts create an area that shades the semiconductor material. One approach to avoiding this problem is to use electrodes formed on transparent surfaces. For example, in U.S. Pat. No. 4,694,116 to Yutaki et al., entitled "Thin-Film Solar Cell", a thin-film solar cell is described which has a two-layered transparent electrode formed on a transparent substrate, a photoelectric conversion section formed on the transparent electrode, and a back electrode formed on the photoelectric conversion section. The photoelectric conversion section is generally constituted as a P/N junction. This device has efficiencies in the 7-9% range, depending on the manner of fabrication. Cells made using the edge-defined film-fed growth-ribbon process are reported to have efficiencies of 14% and the figure for dendritic web cells is 15.5%. The highest thin-film cell efficiency reported is 15.8%, for cadmium telluride. Thin films of silicon on ceramic substrates have yielded efficiencies of 15.7%.
In terms of cost, the cheapest material is silicon. There are three major types of silicon solar cells. The first type uses amorphous silicon. These cells do not possess a regular crystal structure. They can be produced in films of 0.3 microns and their production is relatively simple and cheap. Mass production of these cells is quite easy, with small amounts of material being deposited on to a substrate such as glass or aluminum, and can even be made flexible. Their major drawback is their low efficiency and short life-span. Presently, efficiencies are only 5-7%, however this drops to 3-4% in operation due to amorphous silicon instabilities. It is generally used for small scale applications such as calculators and watches.
The second type uses poly-crystalline silicon. These cells consist of a number of silicon crystals grown as an ingot from which wafers are cut. Their maximum efficiency is generally 15% and is standard material for high output applications. These wafers are of the order of 250-400 microns thick.
The final type uses mono-crystalline silicon. These are the highest efficiency silicon cells available and are cut from carefully grown ingots consisting of one crystal only. However in the past their expense has generally precluded them from anything except "space" applications where mass and area limitations are important. Recent developments in mono-crystalline cell technology has seen their cost reduced to around that of the poly-crystalline cell.
An important criterion is therefore cost per watt capacity, which is a compound of the cost per unit area and efficiency. For example crystalline silicon devices cost about 3.5$/W peak and have an efficiency of about 13%. This means that such devices will cost around 450$/m.sup.2. On the other hand, amorphous silicon devices, with efficiencies around 5% cost about 2.5$/W peak, or about 125$/m.sup.2. So a 10 m.sup.2 array will generate 1.3 kW peak for the crystalline silicon device and 0.5 kW peak for the amorphous silicon device, and they will cost $4500 and $1250 respectively. The low efficiency device is thus more economical.
Cells other than silicon are available and use materials with band-gaps nearer to 1.5 eV, such as GaAs and CdTe. They have higher theoretical efficiencies because their particular band-gap energies are closer to the theoretical optimum than silicon, which has a band-gap of 1.12 eV. They do however use materials which are more expensive, less abundant, and can be environmentally hazardous.
Efficiencies are increased as the light intensity is increased, and photovoltaic cells may be used in concentrator systems where the sun's radiation is focused onto the device using a reflector. This advantage is offset by the need to provide a cooling system, because performance and stability degrade at high temperatures.
There remains a need therefore for devices which are inexpensive to produce, and which exhibit stable operation at elevated temperatures in concentrator applications.
Photocells
These devices comprise a photocathode and an anode. The anode is small, often no more than a wire. It is maintained at a positive potential to attract electrons emitted from the cathode. When light impinges on the photocathode, electrons are released which move to the anode. This flow of electrons effectively reduces the resistance of the device, allowing a current to flow in the external biasing circuit. The magnitude of the current is dependent on the intensity of the incident light. These devices do not generate electricity.
Thermionic and Photoelectric Cells
In U.S. Pat. No. 4,266,179 entitled Solar Energy Concentration System", Hamm teaches that if solar energy is used as the heat source for a thermionic converter, it needs to be concentrated so that the temperature at the thermionic converter exceeds 2,800.degree. K. He goes on to describe multiple reflector units that are able to vary the energy concentration at the transducer by 20,000 to 250,000 fold. When this system is used with the "Radiant Energy to Electrical Power Conversion System" described by Brunson in U.S. Pat. No. 4,188,571 an output of 1.38 kW is projected from a device having electrodes separated by 6.3 .mu.m and a cathode temperature of 3630 Kelvin. Both of these inventions teach that thermionic converters may be used to harness solar energy only if a concentrator is used: they do not teach that thermionic solar energy conversion may be achieved at ambient temperatures. Furthermore, such devices operate by the conversion of light energy to heat, thence the conversion of heat to electricity. They do not teach the direct use of photon energy.
U.S. Pat. No. 4,168,716 to Fowler and Israel, entitled "Solar-Powered Thermionic-Photoelectric Laser", describes a solar-powered thermionic-photoelectric current generator which employs a parabolic telescope for collecting and concentrating sunlight into a narrow beam which is incident upon a thorium-doped tungsten cathode target within an evacuated envelope. This invention uses both thermionic and photoelectric emission from a target to enhance the current generating capabilities of a physical system which might utilize either effect alone. The device is designed so that the space charge of electrons is continuously swept away from the target by the radiation pressure of the light incident upon the target at very large angles of incidence. This invention does not use close spaced electrodes; rather it relies on the radiation pressure of the light to overcome space charge effects. Again this invention teaches that a solar energy concentrator is required in order to use a thermionic-photoelectric generator for harnessing solar energy. This invention also teaches that photoelectric emission is an ancillary source of electrons. The invention does not teach that photoelectric emission is sufficient of itself for the efficient generation of electricity.
Another invention using light to improve the efficiency of thermionic converters is U.S. Pat. No. 3,300,660 to Bensimon, entitled "Thermionic Energy Converter with Photon Ionization". Bensimon describes a device having a capillary emitter, the channels of which permit the penetration of light energy from an external source in order to facilitate the ionization of the atoms of an ionizable material, such as cesium, employed to overcome space charge effects. In this invention, photoelectric emission is not a contributing factor.
It is clear from the above that the art does not teach that pure photoelectric emission can be used for power generation. Where photocathodes have been described, they are for instrument use. For example in U.S. Pat. No. 5,598,062 to Iigami, entitled "Transparent Photocathode" a transparent photocathode is described which composed of a silver layer formed on a transparent substrate, comprising silver particles having an average diameter of 80 to 200 nm, and a silver oxide layer, potassium layer, and a cesium layer. As a result of the silver layer comprising silver particles having dispersive diameters, the transparent photocathode can selectively achieve high sensitivity to an infra-red region of near 1500 nm, and may be thus used in an infra-red analyzer. Although the photocathode is transparent, this invention does not teach that this is an advantage for use in harnessing solar energy for the use of electricity. Indeed, these devices are used for light detection, and as such consume power.
Another invention using a transparent electrode, this time a transparent collector or anode, is described in U.S. Pat. No. 5,028,835 to Fitzpatrick, entitled "Thermionic Energy Production". This invention describes a thermionic device having transparent collector surfaces coated with a thin film of conductive material. This arrangement reduces the conduction of heat by radiation from the hot emitter, thereby increasing the efficiency of the device. It is not taught that the transparent collector directly aids in the generation of electricity from solar energy.
Thus it can be seen from the foregoing that the use of the photoelectric effect to harness solar energy for electricity generation is known only as an adjunct to thermionic emission.
Generation of electricity from solar energy using a device relying on the photoelectric effect alone is not known to the art.
It can also be seen that previous devices using thermionic emission for electricity generation have required the use of solar concentrators to generate high temperatures.

Method and apparatus for photoelectric generation of electricity


This disclosure provides an engineered system comprising: a first nucleic acid molecule encoding a CasX nuclease, and a guide RNA (gRNA) or a second nucleic acid molecule encoding the gRNA, where the first nucleic acid molecule is codon optimized for a eukaryotic cell, and where the gRNA is designed to hybridize with a target site in the eukaryotic cell. Further, this disclosure provides a method of modifying at least one target site in a eukaryotic genome comprising: providing a eukaryotic cell with a CasX nuclease or a first nucleic acid molecule encoding the CasX nuclease, and providing the eukaryotic cell with a guide RNA (gRNA) or a second nucleic acid molecule encoding the gRNA, where the gRNA and the CasX nuclease form a complex, where the gRNA hybridizes to the target site, and where the complex generates a modification at the target site.

RNA-guided endonucleases can be used as tools for genome editing. However, their versatility is limited by restrictions imposed by several requirements, including short recognition motifs referred to as protospacer-adjacent motifs (PAMs) and the fact that some RNA-guided nucleases either exhibit no functionality or greatly reduced functionality in eukaryotic organisms.
CasX was recently discovered to be able to specifically cut plasmid DNA in the bacteria Escherichia coli. See Burstein et al., 2017, Nature, 542:237-241. However, it was unknown whether CasX can be reprogrammed to a) function in a eukaryotic cell, and b) whether CasX can cut chromosomal DNA.
The inventors of the present disclosure have discovered that CasX can be modified to successfully edit a eukaryotic genome.

Targeted endonuclease activity of the RNA-guided endonuclease CasX in eukaryotes


A thin film transistor formed on an insulative substrate includes: a first semiconductor film including a channel region and first source/drain regions; a gate insulating film formed on the channel region of the first semiconductor film; a gate electrode formed on the gate insulating film; an insulating film formed on surfaces of the gate electrode; and a second semiconductor film formed on the first source/drain regions of the first semiconductor film. The second semiconductor film includes second source/drain regions which make contact with the first source/drain regions of the first semiconductor film, respectively, the second source/drain regions being separated above the gate electrode by a gap.

1. Field of the Invention
The present invention relates to a thin film transistor (hereinafter, simply referred to as a "TFT") suitable for use in an active matrix type liquid crystal display device (hereinafter, simply referred to as an "AMLCD"), an image sensor or the like, and a method for producing the same.
2. Description of the Related Art
Recently, a liquid crystal display has been receiving much attention as a flat panel display. Specifically, AMLCDs have been incorporated in televisions, projectors, notebook personal computers and the like due to their excellent display quality. In such an AMLCD, amorphous silicon (a-Si) TFTs are used as switching elements for pixels.
However, since the field effect mobility of the a-Si TFT is as low as about 1 cm.sup.2 /V.multidot.s, the a-Si TFT is not usable to form a driving circuit. Therefore, it is necessary to mount, by employing a TAB (Tape Automated Bonding) technique or the like, integrated circuits as drivers along a periphery of a substrate where the switching transistors are formed to produce a display section.
On the other hand, the field effect mobility of a TFT made of polycrystalline silicon (poly-Si) can be as high as 100 cm.sup.2 /V.multidot.s or higher. Thus, the poly-Si TFT can be used to form a driving circuit that can be formed on the same substrate with the switching transistors. In particular, a TFT made of a low-temperature poly-Si, which can be fabricated through a process conducted at a temperature of 600.degree. C. or lower, has been undergoing vigorous studies due to the fact that it can be formed on an inexpensive glass with a lower strain point.
Problems of the poly-Si TFT remaining to be solved include reduction in an off-current (i.e., a leakage current flowing between a source region and a drain region while the transistor is turned off) and enhancement of the current driving ability. In order to solve the above-mentioned problems, a thinner poly-Si film has been considered. A thinner poly-Si film allows an increase in the sheet resistance, thereby reducing the off-current. Moreover, the thinner poly-Si film allows complete depletion of the poly-Si film while the transistor is turned on, thereby reducing a threshold voltage V.sub.TH and enhancing the current driving ability.
However, the thinner poly-Si film increases the resistance of source/drain regions as well. Accordingly, the above-mentioned effect of enhancement in the current driving ability is contradicted. For example, a poly-Si film having an impurity concentration of about 10.sup.20 cm.sup.-3 has a sheet resistance of about several hundred .OMEGA./.quadrature. when the thickness thereof is 100 nm, and a sheet resistance of about several k.OMEGA./.quadrature. when the thickness thereof is 10 nm. Upon simulation, in the case where a TFT has a ratio of a channel length L and a channel width W (L/W) of about 10 .mu.m/10 .mu.m, the resistance of source/drain regions is preferably several hundred .OMEGA. or lower considering the high-speed operation required in a driving circuit. If the channel length of the TFT is shortened in order to realize further enhanced high-speed operation, it is necessary to further reduce the resistance of the source/drain regions. Accordingly, a TFT made of a thinner poly-Si film is not preferable because of deterioration in the current driving ability.
In order to solve the above-described problem, a TFT 400 shown in FIG. 4 has been proposed in which the source/drain regions are made relatively thick while a channel region is made relatively thin (Japanese Laid-Open Patent Publication Nos. 6-163899 and 6-163900).
The TFT 400 shown in FIG. 4 includes a poly-Si film 402 having a channel region and source/drain regions formed on a glass substrate 401, a gate insulating film 403 formed on the poly-Si film 402 and a gate electrode 404 formed on the gate insulating film 403. The TFT is characterized in that the thickness of the poly-Si film 402 is greater in the source/drain regions than in the channel region. In other words, the channel region is thinner than the source/drain regions.
The above-described structure is covered with an interlayer insulating film 405. Source/drain electrodes 406 are formed on the interlayer insulating film 405 so as to be electrically connected to the source/drain regions, respectively, via contact holes provided through the interlayer insulating film 405.
In such a conventional TFT, the step of forming the gate electrode 404 comes after the step of making the source/drain regions thick or the step of making the channel region thin. Accordingly, the relative location of the gate electrode 404 may be greatly offset depending on the accuracy of mask alignment for forming the gate electrode 404. Therefore, conventionally, it is difficult to form a TFT having dimensions in precise accordance with the design and with satisfactory reproducibility.
In the case where a glass substrate is used instead of a quartz substrate, it is difficult to form a plurality of TFTs on a large substrate with accuracy due to problems such as that the substrate may contract in size upon heating during the production process. In order to prevent variation in the transistor characteristics or malfunction in the transistor caused by the dislocation of the gate electrode, the gate electrode needs to be located on the channel region without fail, taking in consideration the process margins such as the accuracy of mask alignment. In order to do so, the plane area of the relatively thin channel region needs to be made large. As shown in FIG. 4, the relatively thin portion of the poly-Si film 402 (i.e., a thin film region) is formed so as to have a size sufficiently greater than the width of the gate electrode 404 along the channel length.
However, in such a structure, the entire area of the thin film region is not used as the channel region and the marginal portions are used as parts of the source/drain regions. Referring to FIG. 4, portions 407a and 407b of the thin film region are shown as the parts of the source/drain regions.
In such a structure, the sheet resistance (series resistance) of the source/drain regions is increased. In the case of a large substrate (e.g., 300 mm.times.400 mm), the process margin is about 2 to 4 .mu.m. Accordingly, when L/W of the TFT is about 10 .mu.m/10 .mu.m, resistance increased due to the process margin is approximately 1 k.OMEGA. which is substantial.
As for the switching transistors, the resistance of the source/drain regions causes little problem, and it is rather important to reduce the off-current.
The off-current cannot be sufficiently reduced only by making the poly-Si film thinner. Accordingly, it has been considered to provide a structure having a substantially undoped region (i.e., an offset structure) or a structure having a lightly doped region (i.e., an LDD structure) between the gate electrode and the source/drain regions. Moreover, semiconductor regions with a bandgap larger than that of other semiconductor regions may be provided between the gate electrode and the source/drain regions.
An undoped region or a lightly doped region formed between the gate and the drain allows reduction in the off-current by easing the electric field concentration at the end of the drain. A semiconductor having a larger bandgap is effective in reducing the off-current due to its smaller carrier density at thermal equilibrium which results in high resistance.
Usually, the offset structure or the LDD structure is formed during the step of implanting ions for forming the source/drain regions, by masking portions to be the offset regions or the LDD regions with a resist. In order to locate semiconductor regions with a larger bandgap at prescribed regions, first, a semiconductor layer with a larger bandgap is deposited and then unnecessary portions of the semiconductor layer are selectively etched away.
The offset or LDD regions are formed (in vertical direction) from a semiconductor layer having a wide bandgap. For a TFT for switching a pixel, it is more important to lay stress on obtaining a lower off-current, whereas, for a TFT used for a driver, it is more important to lay stress on obtaining a higher on-current to enhance the driving ability thereof. Thus, in the case of using the TFT for a driver, it is preferable not to form the offset or LDD regions. It is, however, possible to form the offset or LDD layers when it is desired to improve the reliability of the TFT.
The offset regions, the LDD regions or the semiconductor regions with the larger bandgap are formed in a symmetrical manner with respect to the gate electrode. Otherwise, the on-current will be asymmetric with respect to positive and negative charges of a source-drain voltage, thereby causing problems such as variations in writing signals.

Thin film transistor and method for producing the same


The device comprises a structure (1) supporting a light beam source (2), a beam guide and a camera assembly (3), the light beam source (2) being arranged to direct an outgoing beam of light (I) into the beam guide which projects the outgoing beam (P) onto a target surface to sweep the beam around an endless path (E) on the target surface, scans synchronously around the endless path (E) to receive light returning from the portion of the path (E) illuminated by the outgoing beam (P), and directs the returning light (P) onto a light sensor (12) provided in the camera assembly (3); the beam guide comprising a rotatable wedge prism (5) arranged such that the outgoing beam (2) is transmitted through relatively inclined surfaces (9, 10) of a projecting element of the prism (5) as it is rotated to direct the beam (P) to sweep around the endless path (E) and the light returning from the portion of the path illuminated by the beam (P) is received through relatively inclined surfaces (9, 10) of a receiving element of the prism (5) as it is rotated to direct the returning light (P) onto the light sensor (12). The position of the image formed on the sensor (12) is indicative of the range of the illuminated portion of the target surface and, from a knowledge of the position of the scanning beam, its three-dimensional position can be determined. An image of the sensed topology can thus be built up as the target surface is scanned.

In order to guide a robot arm in a welding robot it is necessary to locate the seam to be welded relative to the welding electrode. It is desirable to obtain three dimensional (3D) information concerning the topology of the target surface in which the seam lies since this enables much more information to be obtained about the surface and attributes much greater versatility to the welding robot.
An imaging device capable of obtaining 3-D information about a target surface has been proposed by the Caterpillar Tractor Co., in the U.S. Pat. No. 4,501,950. In this document, the disclosed imaging device comprises a support structure supporting a laser beam source, arranged to direct an incident laser beam into a beam guide whereby the laser beam is directed to traverse a circular path on the target surface. The beam guide is also provided with a window which rotates synchronously with the incident laser beam in order to view an image of the target surface illuminated by the laser beam. The window forms part of a receiving portion of the beam guide which includes an assembly of mirrors or prisms arranged to reflect the image into a chamber which extends along the axis of rotation of the beam guide, and to direct the image through the chamber. A dove prism is mounted in the chamber and supported by a sub-assembly of the beam guide to rotate at half the speed, but in the same direction, as the projecting portion of the beam guide. Thus, as the image passes through the dove prism it is " de-rotated" with respect to the support structure. Upon leaving the dove prism the image is directed into a camera assembly fixedly mounted above an aperture in the chamber.
The camera assembly of this device includes a focusing lens arrangement which directs the "de-rotated" image onto a one-dimensional sensor array. The sensor array is sensitive to the linear position at which the laser beam strikes it, and transduces this information into electrical signals which are transmitted to a data processor. The information is processed in conjunction with the angular orientation of the light guide which corresponds to the position of the laser beam on the circular path. The information concerning the angular orientation is obtained from a substantially conventional transducer.
It will be appreciated that it is highly desirable that an imaging device located on the end of a robot arm should be as light and compact as possible. However, it is also necessary to accommodate the conflicting requirement of being robust, so that the imaging device can endure the very hostile conditions experienced during a welding operation. The quality of the optics, particularly the light guide, dramatically affects the performance of the imaging device as a result of losses and distortion in transmission.
Some of these problems can be alleviated by omitting the optical "de-rotation" of the image, and using a two dimensional light sensor in the camera assembly instead and devising a suitable program for "de-rotating" the image by computer, as suggested in the aforementioned U.S. patent. However, the difficulties of processing the information obtained, and the loss of immunity to multiple reflection problems in particular, is often such as to outweigh the advantages of this tactic.
The complexity of imaging devices constructed in accordance with U.S. Pat. No. 4,501,950, results in them being large, heavy, difficult to set up, expensive and lacking in robustness. Hence the versatility of the prior art imaging devices is severely limited.
It is an objective of the present invention to provide an imaging device suitable for mounting on the arm of a welding robot, close to the welding torch, in order to obtain 3-D topological data from a target surface, which alleviates the aforementioned disadvantages of the prior art.

Imaging device with prism scan element means


A synchronized manual transmission of a motor vehicle is actuated by a shift roller. The transmission gears can be shifted only by the simultaneous closing of two synchronizer clutches. At least one sliding sleeve of a synchronizer clutch is adjustable independently of the position of the shift roller into the neutral position and inversely from the neutral position into the position determined by the shift roller.

This application is related to U.S. Ser. No. 08/022,108 filed on even date herewith, now U.S. Pat. No. 5,365,800.
The present invention relates to a manual transmission of a motor vehicle having a plurality of transmission gears which can be shifted by synchronizer clutches, gearwheel plates being formed by mutually meshing loose wheels and fixed wheels, and the transmission gears being shiftable by the coupling of the loose wheels with the pertaining transmission shafts.
A manual transmission of this type is shown in U.S. Pat. No. 4,409,858, and is controlled by a shift roller and used mainly in motorcycles. It is a disadvantage of that transmission that a complicated shifting arrangement is required in order to shift from the higher transmission gears directly into idling.
An object of the invention is to provide a manual transmission which can be shifted in an easier and in an operationally more reliable manner.
This and other objects are achieved by the present invention which provides a manual transmission of a motor vehicle, comprising a plurality of transmission gears with gearwheel pairs formed by mutually meshing loose wheels and fixed wheels, and synchronizer clutches coupleable to the transmission gears such that the transmission gears are shifted by the simultaneous closing of two of the synchronizer clutches, the synchronizer clutches having sliding sleeves. A shift roller is coupleable to the synchronizer clutches to actuate the synchronizer clutches. At least one of the sliding sleeves is adjustable independently of the position of the shift roller into a neutral position and from the neutral position into a position determined by the shift roller.
Even when all transmission gears can be shifted only by the simultaneously closing of two synchronizer clutches, as in embodiments of the invention, it becomes possible to bring the sliding sleeve of at least one synchronizer clutch, independently of the respective position of the shift roller, into the neutral position and inversely from the neutral position into the position determined by the shift roller.