A method and structure for a lower capacitor electrode for a dynamic random access integrated circuit. A polysilicon gate layer is formed over a thin layer of oxide in a first region of a semiconductor substrate. Another oxide layer is then formed overlying the polysilicon gate layer. A polysilicon layer which was doped by S/D implant including the lower capacitor electrode self-aligns and forms overlying a second region of the semiconductor substrate and over the oxide layer on the polysilicon gate layer. A nitride layer forms on the lower capacitor electrode portion overlying the second region. Exposed portions of the polysilicon layer are then oxidized. The S/D was formed by driving dopant from implanted second layer polysilicon. Portions of polysilicon under the nitride layer corresponding to the lower capacitor electrode oxidizes at a slower rate than the exposed portions of the polysilicon. Such sequence of steps forms a self-aligned lower capacitor electrode for a dynamic random access memory integrated circuit.

The present invention relates to semiconductor integrated circuits and their manufacture. The invention is illustrated in an example with regard to the manufacture of a storage cell capacitor for a dynamic random access memory (DRAM) integrated circuit, but it will be recognized that the invention has a wider range of applicability. Merely by way of example, the invention may be applied in the manufacture of other semiconductor devices such as local interconnection for SRAM, among others.
Capacitors and metal oxide field effect (MOS) transistors and their manufacture are generally known in the art. In the fabrication of a DRAM integrated circuit, it is necessary to fabricate a DRAM cell which includes the MOS transistor and a storage cell capacitor. Examples of DRAM cells include the single poly/diffused bit line cell and double poly diffused bit line cell structures. These cell structures are often not compatible in the manufacture of present DRAM integrated circuits having smaller line widths and greater memory capacity.
In the single poly/diffused bit line DRAM cell structure, each cell includes a field effect transistor (FET) that is adjacent to a storage cell capacitor, thereby providing a substantially linear configuration on the semiconductor substrate. This cell structure typically occupies a larger region which often limits the amount of cells that can be fabricated onto the substrate. Accordingly, the single poly/diffused bit line cells are often not desirable when forming a densely packed structure typically needed for the higher memory DRAM integrated circuits.
Other cell structures such as the double poly/diffused bit line cell are also limiting for the higher memory DRAM integrated circuits. Though such cell may form a densely packed unit for each DRAM device, other limitations often exist, typically lower capacitance of the storage cell capacitor and undesirable capacitance variations among different lines of the DRAM cells.
Further problems may occur during the manufacture of higher memory DRAM integrated circuits by use of the above-mentioned cell structures. For example, as line widths become smaller in the DRAM integrated circuit, mask alignment often becomes more difficult to perform accurately, especially at a critical masking step. This is likely to cause misalignment which often decreases the yield of the integrated circuit devices on a typical semiconductor wafer. Accordingly, it is often desirable to reduce the number of critical masking steps or provide a process that has self-aligning steps.
In addition, multiple implanting steps, especially for high-dose arsenic implants, of the source/drain regions of the field effect devices in both the core region and peripheral region are likely to create more damage to shallower diffusions of semiconductor in the denser DRAM cells. Such damage to the semiconductor often creates current leakage of the core memory area, among other related problems, thereby decreasing the reliability and performance of the particular semiconductor integrated circuit. In a conventional DRAM integrated circuit, at least three separate implanting steps of separate source/drain regions are performed, typically increasing the damage to the semiconductor in the core memory region.
Further, the increased device complexity of the higher memory DRAM integrated circuits often creates more process steps. More process steps are likely to increase the possibility of introducing defects into the device, typically caused by particles, operator handling, and the like. More process steps also tend to promote a longer product turn-around-time (TAT), typically defined as the time from wafer start to final test for the manufacture of the DRAM integrated circuit. The longer TAT is also likely to create higher costs in the manufacture of the integrated circuit.
Still further, it is often desirable to manufacture devices with features therein for easy identification. Competition in the semiconductor industry creates a need for identifying products for the purpose of infringement. Piracy of semiconductor designs also continues to increase as world-wide demand for semiconductor chips grows. However, it is often difficult to determine whether a competitor's chip actually infringes a patented process or has been pirated without extensive investigation, that is, reverse engineering and very detailed analysis by experts. Accordingly, it is desirable to manufacture a semiconductor chip with features therein for easy identification.
From the above it is seen that a method of fabricating semiconductor devices that is easy, reliable, cost effective, and identifiable is often desired.

Semiconductor having self-aligned polysilicon electrode layer


A dual-mode network access point device for enabling a user to select between at least two telecommunication service providers using the user's existing telecommunications wiring. The device includes a wireless interface circuit adapted for coupling one or more antennas which are used for transmitting signals to and receiving signals from a wireless service provider and a switching circuit for selectively coupling a first telecommunication device between a wireline service provider and the wireless interface circuit is provided in the device. The device further includes a controller circuit which enables the switching circuit automatically in response to an incoming call and on command to select either the wireline service provider or the wireless interface circuit.

The prior art describes many different methods for gaining access to alternative telecommunication service providers. For example, present cellular telephones allow a subscriber to switch between two different carriers, i.e., an A carrier or a B carrier, on a per-call preference. One such telephone is described in U.S. Pat. No. 5,127,042 entitled CELLULAR CORDLESS TELEPHONE issued to Gillig et al. on Jun. 30, 1992. There, a cellular telephone is described which is capable of placing a telephone call using the subscriber's cellular carrier or a telephone call via the base of a cordless telephone which uses the subscriber's telephone landline carrier. Whenever the cellular telephone is within range of the base of the subscriber's cordless telephone base, the cellular telephone automatically operates as a cordless telephone and selects the subscriber's telephone landline carrier.
Similarly, there are telecommunication systems where wireless telephones and conventional wired telephones are integrated to permit an in-progress telephone conversation to be transferred between wired and wireless telephones without further action by the telecommunication switch that facilitated the initial call. Such a system is described in U.S. Pat. No. 5,390,233 entitled TELEPHONE CALL TRANSFER BETWEEN A WIRELESS AND WIRED TELEPHONE issued to Jensen et al. on Feb. 14, 1995. As described therein, a telecommunications switch and a wired telephone are connected respectively to first and second wired communication channels. A third wired communication channel is coupled to a radio frequency base station that supports a plurality of concurrent wireless communication channels to wireless telephones. An interface circuit coupled to all three channels switches the connection of the first channel associated with a telecommunications switch between the second and third channels, and hence switches the established connection between the wired and wireless telephones.
The prior art also describes other systems for selecting between a plurality of telecommunication service providers. In U.S. Pat. No. 5,371,782 entitled METHOD AND APPARATUS FOR SELECTING A PREFERRED SERVICE PROVIDER DURING A CALL SETUP IN A CALL SETUP IN A PUBLIC CORDLESS TELEPHONE SYSTEM, issued to Casey, III et al. on Dec. 6, 1994, there is described a public telephone system wherein a cordless telephone handset unit can be used to select a preferred service provider from a plurality service providers. By generating a service request containing a specific carrier request code, the handset selectively identifies an available public base unit served by the desired local service provider and then establishes a communications link with this base unit.
In U.S. Pat. No. 5,341,415 entitled METHOD AND APPARATUS FOR SHARING OF COMMON IN-HOUSE WIRING TO PERMIT MULTIPLE TELEPHONE CARRIERS TO SERVE THE SAME CUSTOMER, issued to Baran on Aug. 23, 1994, there is described a system which enables two or more telecommunication carriers to automatically connect to existing in-house telephone wiring according to the choice of the calling party.
Current methods and techniques, however, do not allow the higher-level decision, that of selecting one of the potentially available service access methods, in the hands of the user. Instead, as described above, the prior art allows the selection of a service provider to made in the network, as on the landline carrier, or in the air-interface, on the wireless access.
Accordingly, a need exists for a method which allows a user to select from available service providers based on cost or quality of service, either through stored profiles or at the user's option.


A method of adjusting a frequency response in a stripline filter device having a pair of stacked dielectric substrates with a plurality of stripline resonator conductors being sandwiched therebetween, wherein the frequency adjusting of the filter is performed by partially exposing the open circuit end of each of the resonator electrodes or a filamentary conductor for connecting the open end to the ground conducting layer on the outer surface of one of the dielectric substrates and then partially removing the partially exposed open circuit end of each resonator electrode or the partially exposed filamentary conductor connected to the open circuit end.

The present invention relates to a method of adjusting a frequency response in a microwave stripline filter device which may be used as a band-pass filter for example.
A variety of microwave stripline filters that can be used as bandpass filters for microwaves are known in the art.
FIG. 1 of the accompanying drawings illustrates a microwave strip line filter of a known type which comprises a pair of dielectric substrates 1a and 1b made of dielectric ceramic material having a high dielectric constant and a lower dielectric loss such as BaO-TiO.sub.2 or BaO-TiO.sub.2 -rare earth or the like, the dielectric substrates 1a and 1b being stacked to each other. The dielectric substrates 1a and 1b are provided with external ground conducting layers 2a and 2b on the peripheral portion and bottom surface thereof, respectively. On the upper surface of the lower dielectric substrate 1a are disposed a plurality of stripline resonator conducting layers 3a which operate as a filter element. Each resonator conducting layer 3a has one end connected to the ground conducting layer 2a to form a short circuit end, and the other end or an open circuit end spaced from the ground conducting layer 2a. The open circuit ends of the respective resonator conducting layers 3a are alternately disposed so as to form an interdigitated configuration. The upper dielectric substrate 1b is fixed on the lower dielectric substrate 1a, and the ground conducting layers 2a and 2b of the respective dielectric substrates are connected to each other. One example of such arrangements is disclosed in U.S. Pat. No. 4,157,517.
It is known that the response frequency of the stripline filter device of the above described type depends upon the dielectric constant of the used dielectric substrates and the dimensions of the respective resonator conductors. Upon the manufacturing of the filter devices the dielectric constant of the substrates and the dimensions of the resonator conductors are rigorously controlled. However, the manufactured filter devices inevitably show variations in terms of these factors and require an operation of frequency adjustment after the pair of dielectric substrates are assemblied.
The stripline filter device as illustrated in FIG. 1 is designed to initially have a resonance frequency lower than a desired value and after assemblying the pair of the dielectric substrates 1a and 1b to form the filter, the external conductor or ground conducting layer 2b provided on the upper surface of the upper substrate 1b is partially removed at regions 4 adjacent the open circuit ends of the resonator conducting layers 3a to reduce the stray capacitance between the external conducting layer 2b and the respective resonator conducting layers 3a thereby increasing the response frequency of the filter to the desired value.
With this adjusting method, however, the frequency response may be deviated again when the assembled filter body is contained in a casing after the adjustment of the frequency response is made as the removed regions 4 are brought to contact with or close to the upper inner wall of the outer casing so that the stray capacitance may be changed from the adjusted value.
In order to solve this problem, an attempt has been proposed in Japanese Patent Kokai No. 1-251801. According to a method of frequency adjustment disclosed in this reference, in a stripline filter in which a pair of dielectric substrates are stacked together with a plurality of resonance conductor strips arranged therebetween, openings are formed on the lateral sides of dielectric substrates at the positions facing the short circuit ends of the resonance conductor strips for adjustment of the response frequency.
Another solution for the problem has been proposed in Japanese Patent Kokai No. 2-292901 which discloses a method of frequency adjustment for a microwave stripline filter having a pair of dielectric substrates to be stacked, each provided on the outer surface with a ground conductor, together with a plurality of resonator electrodes arranged on the inner surface of at least one of the dielectric substrates, one end of each resonator electrode being connected to the the ground conductor to form a short circuit end, and the other end or an open circuit end being spaced from the ground conductor, wherein the ground conductors are partially removed at the locations on the lateral sides of the dielectric substrates facing the open ends of the resonator electrodes, at the locations connected to the short circuit ends of the resonator electrodes and at the locations where notches are formed on the lateral sides of the dielectric substrates, the notches facing the open ends of the resonator electrodes.
A further solution has been proposed in Japanese Patent Kokai No. 1-219580 which discloses a method of frequency adjustment for a stripline filter having a pair of dielectric substrates stacked together with a plurality of resonance conductor strips arranged therebetween. According to this method ground conductors are provided on the outer surface of each of the dielectric substrates except the lateral sides, the short circuit end of each of the resonator conductor strips is extended as far as one of the ground conductors along the lateral sides, the open end of each of the resonator conductors is removed together with a portion of the corresponding lateral side of either of the corresponding dielectric substrate, and a piece of corrective conductor is provided on the open circuit end of each of the resonator conductors.
The known methods of frequency adjustment as mentioned above have disadvantages. Firstly, while the method disclosed in Japanese Patent Kokai No. 2-251801 can reduce the response frequency of the filter by forming the openings on it for adjusting the response frequency, it can not raise the frequency once it is made too low. Besides, the proposed method involves cumbersome operations.
While the method disclosed in Japanese Patent Kokai No. 2-292901 can raise the response frequency of the filter, the extent to which it can adjust the frequency is rather limited and the effect of the frequency adjustment becomes poor when the open circuit end of each of the resonator conductors and the corresponding ground conductor are separated from each other by a considerable distance.
With the method disclosed in Japanese Patent Kokai No. 1-219580, the response frequency of the stripline filter can be increased to a considerable extent. However, the profile of the filter needs to meet certain given requirements if the method works effectively.

Method of adjusting frequency response in a microwave strip-line filter device


A digital ring oscillator outputting a toggled clock signal. The clock signal is generated by a plurality of electronic cells that are arranged in series. At least one of the plurality of electronic cells receives a feedback of the clock signal. Control signals are received at an input for the plurality of electronic cells. Each electronic cell includes a first logic gate, a second logic gate, and an inverted logic gate coupled between the first logic gate and the second logic gate. For each electronic cell, a respective control signal controls whether an output signal received from the first logic gate of a preceding electronic cell is transferred through the first logic gate to the first logic gate in a succeeding electronic cell, or is inverted and transferred through the second logic gate to the second logic gate in a preceding electronic cell, based on the control signal.

Many integrated circuits (IC) use a clock signal for timing or synchronizing different parts of a circuit. This clock signal is typically provided by an oscillator circuit.
One common form of oscillator circuit is a ring oscillator. In a simple arrangement, a ring oscillator is formed from a feedback circuit which includes a delay line and an inverter. The frequency of a ring oscillator is determined by the delay of the delay line.
One problem of typical oscillator circuits is that the clock frequency may vary with process, voltage, and temperature (i.e., PVT) changes. Therefore, the oscillator may need to be adjusted periodically to maintain a specified frequency, by adjusting the delay of the delay line.


An information storing device includes a storage device in which one or more storage areas are generated for storing electronic data therein, wherein in the storage device at least one of first and second processes is set on a storage area basis; a storing part configured to, when the information storing device has received electronic data and a designation of the storage area from one of a plurality of electronic apparatuses, store the received electronic data in the storage area designated by the received designation; and an executing part configured to, when the received electronic data is stored by the storing part, perform the first process on the stored electronic data if the first process is set in the storage area in which said electronic data is stored, and perform the second process using the stored electronic data if the second process is set in the storage area in which said electronic data is stored.

For example, Japanese laid-open patent publication No. 2008-191711 discloses a printing system utilizing a personal computer wherein when data is input into a particular folder as a hot folder, a print process set in advance for the folder is performed for the input data.
In recent years, users are utilizing various electronic apparatuses for outputting electronic data such as a printer, a Multi Function Peripheral and a projector, and various information processing devices such as a mobile phone, a smart phone and a tablet terminal. In a system where the electronic apparatus and the information processing device are utilized in cooperation, value is expected to be improved by utilizing these electronic apparatus and information processing devices in cooperation.
However, according to a prior art system utilizing the electronic apparatuses and the information processing devices, the respective information processing devices, that utilize a folder (a process defined folder) with which a predefined processing is performed for the input data, need to have functions of storing the data in the folder. Further, functions of displaying the folder and storing the data in the folder need to be adapted to the apparatus that has the process defined folder.
In this way, according to the prior art system utilizing the electronic apparatuses and the information processing devices, it is difficult to coordinate the electronic apparatuses and the information processing devices with the apparatus that has the process defined folder in utilizing the process defined folder.
An object of this disclosure is to provide an information storing device, an information storing system and a method that can execute processing utilizing a process defined folder in conjunction with each other.

Information storing device, information storing system and method


A method for arranging a drive unit in a revolving door, the drive unit being arranged at a ceiling element of the revolving door and configured to drive a turnstile of the revolving door, includes: arranging an adapter element at the ceiling element; arranging an electronically commutated multipole motor at an adapter element; and adjusting, by the adapter element, the multipole motor relative to the turnstile of the revolving door.

1. Field of the Invention
The present invention is directed to a method for the arrangement of a drive unit in a revolving door, wherein the drive unit is arranged at a ceiling element of the revolving door and serves to drive a turnstile of the revolving door.
2. Description of the Related Art
EP 2 072 737 A2 shows an arrangement of a drive unit in a revolving door, wherein the drive unit is arranged at a ceiling element of the revolving door. The method for arrangement includes arranging the drive unit, which is formed of a motor and a gear unit. The individual components of the drive unit are installed in an installation space in the ceiling of the revolving door after the frame of the revolving door has been installed and after the turnstile has been installed. As a rule, the components of the drive unit are located above a ceiling construction which upwardly terminates the receiving space for the turnstile in the revolving door. This brings about disadvantages with respect to accessibility of the drive unit so that, for example, maintenance work is also made more difficult. Special sealing steps are required in particular because assemblies installed on top are often exposed to atmospheric conditions. Further, there are cosmetic disadvantages with respect to the presentation of the revolving door because the installation height of conventional drive units in or above a ceiling element of the revolving door often exceeds 200 mm.

Method for the arrangement of a drive unit in a revolving door


Embodiments provided herein recite methods and systems for position determination based on hybrid pseudorange solution data. In one embodiment, navigation satellite system (NSS) pseudorange data is received for high yield pseudoranges. In addition, NSS pseudorange data is received for high accuracy pseudoranges. The high accuracy pseudoranges and selected ones of the high yield pseudoranges utilized by a hybrid PVT processor to determine a hybrid NSS-based location solution.

A Navigation satellite system (NSS) is a space based radio positioning network for providing users equipped with suitable receivers highly accurate position, velocity, and time (PVT) information. One of the most recognizable NSS systems is the global positioning system (GPS) developed by the United States of America, although there are numerous other systems including local NSS's that utilize fewer satellites in a geosynchronous orbit. Thus, although the following background describes the operation of the GPS system in particular, it is appreciated that the description is meant to provide a generic overview of NSS operations as opposed to specific reliance on a single NSS.
In general, the space based portion of GPS comprises a constellation of GPS satellites in non-geosynchronous 12-hour orbits around the earth. GPS satellites are located in six orbital planes with four of the GPS satellites in each plane, plus a number of "on orbit" spare satellites for redundancy. The orbital planes of the GPS satellites have an inclination of 55 degrees relative to the equator and an altitude of approximately 20,200 km (10,900 miles) and typically complete an orbit in approximately 12 hours. The positions of GPS satellites are such that a minimum of five of the total constellation of GPS satellites are normally observable (above the horizon) by a user anywhere on earth at any given time.
NSS position determination is based upon a concept referred to as time of flight (TOF) ranging. For example, each of the orbiting GPS satellites broadcasts spread spectrum microwave signals encoded with positioning data and satellite ephemeris information. Essentially, the signals are broadcast at precisely known times and at precisely known intervals. The signals are encoded with their precise time of transmission.
The signal is received at a NSS receiver designed to determine the time of flight from satellite to receiver by synchronizing a local replica of the satellite signal and determining the time of flight of this signal, compare it to the time of transmission, and to demodulate the satellite orbital data contained in the Satellite Data Message. The coded satellite signal contains information describing when the signal was sent from the satellite. The NSS receiver determines the time between transmission of the signal by the satellite and reception by the receiver. Multiplying this by the speed of light gives what is termed the pseudorange measurement of that satellite. It is called a pseudorange because of the many kinds of errors that occur due to clock errors, propagation errors, multipath errors, and the like.
If the NSS receiver clock were perfect, this would be the range measurement for that satellite, but the imperfection of the clock causes it to differ by the time offset between actual time and receiver time. Thus, the measurement is called a pseudorange, rather than a range. However, the time offset is common to the pseudorange measurements of all the satellites. By determining the pseudoranges of four or more satellites, the NSS receiver is able to determine its location in three dimensions, as well the time offset. In addition, because the signal is consistently generated and broadcast, the NSS receiver is able to determine position, velocity, and time (PVT) information on an ongoing basis thereby allowing navigation from point to point.

Position determination based on hybrid pseudorange solution data


A dolly comprising a chassis, a castor having a fork and a wheel rotatably mounted to the fork, and a fastener for fixing the fork of the castor to the chassis of the dolly. The fastener comprises a head which is shaped to the peripheral shape of the wheel of the castor.

The present invention relates to logistics equipment. In particular, the invention relates to dollies. More specifically, the invention relates to a fastener and dolly according to the preamble portions of the independent claims.
There is known a vast variety of different devices used for transporting parceled goods. Typically pieces or stacks thereof are loaded onto a wheeled platform, on which they are conveyed to shop floor or storage. These wheeled platforms are called dollies. Traditional dollies feature a rectangular chassis welded together from tubes having a rectangular profile. Fixed castors are secured to one end of the dolly by means of bolts or riveted joints. Each castor is typically fixed with four bolts. Fixed castors are such that the wheel of the castor is permanently aligned with one side of the dolly. At the opposite end of the dolly, castor wheels are provided with a similar bolt or riveted joint. Due to the articulated construction, the castor wheels may turn about an axis which is orthogonal to the axis of revolution of the wheel, i.e. about the vertical axis.
The top face of the dolly has wells or recesses for receiving the wheels of a superposed dolly. The wheels of fixed castors are received to recesses which are shaped such that the wheels fit tightly, whereby there is minimal play between the dollies. The wheels of castors, on the other hand, are received to a well which is formed by a plate having nodules welded to the plate. The nodules are used for providing lateral support for the wheel such that the wheel is locked into place, thus preventing movement of the castor joint during transportation of a dolly stack.
The present systems for attaching the wheels to a dolly and for positioning the wheels of the dollies when dollies are stacked upon each other are labor intensive and expensive because of the weld nodules for locking the castor wheel, four fasteners to assemble and screw in etc.
It is therefore an aim of the present invention to provide a simplified dolly, the castor wheels of which are locked into position. A further aim of one embodiment of the invention is to provide a dolly wherein the castor wheels are attached to the dolly by a single fastener. A further aim of another embodiment of the invention is to provide a dolly wherein a single fastener functions as a attachment means for the castor wheels as well as a positioning element.


A laser scanning system for reading bar code symbols in which the "dead zone" is minimized by appropriate positioning and size of the optical components. The vertical height (non-scan direction) of the collecting mirror is minimized, while the horizontal width (scan direction) is increased proportionally, thereby collecting less specular reflected light. The optical components are mounted on a single printed circuit board so that the optical paths are angularly offset for minimizing the specular component, while maintaining an optically-aligned relationship. The printed circuit board may be mounted in hand held laser scanning head having a single exit window.

Field of the Invention
This invention generally relates to laser scanning systems for reading indicia having portions of different light reflectivity such as bar code symbols and, more particularly, to a lightweight, multi-component, portable laser diode scanning head supportable by a user and aimable at each symbol to be read. Still more particularly, this invention relates to deactuating at least one of the components, e.g. the laser diode, during part of each scan of the symbol; minimizing the dead zone within the field of view of a detector in the head, in which dead zone specular reflection may prevent a successful decode and reading of the symbol; and resisting separation of parts of the head unless an electrical cable connecting the head to the remainder of the system is first removed.

Laser diode scanner with minimized dead zone


In embodiments, apparatuses, methods and storage media are described that are associated with menu interfaces for media source and content navigation. In embodiments, an apparatus to control a remote computing device may include a wireless transmitter; a capacitive touchpad; and logic operably coupled with the wireless transmitter and capacitive touchpad. In various embodiments, the logic may be configured to: detect a change in position and/or a velocity of a change in position of a tactile input received at the capacitive touchpad. In various embodiments, the logic may be configured to generate, based at least in part on the detected change in position and/or velocity of the change in position, a signal configured to cause the remote computing device to perform an operation associated with provision of a media content for consumption. In various embodiments, the logic may be configured to transmit the signal with the wireless transmitter directly to a wireless receiver of the remote computing device.

The background description provided herein is for the purpose of generally presenting the context of the disclosure. Unless otherwise indicated herein, the materials described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
Advances in computing, networking and related technologies have led to proliferation in the availability of media content, and the manners in which the content is consumed. Today, myriad media content may be made available from various sources of media content, including but not limited to fixed medium (e.g., Digital Versatile Disk (DVD)), broadcast, cable operators, satellite channels, Internet, and so forth. Users may consume content with a television set, a laptop or desktop computer, a tablet, a smartphone, or other devices of the like. In some cases, navigating through large numbers of media content and/or through heterogeneous sources of media content with existing remote controls may be cumbersome.


An optical pulse generator includes a single-wavelength light source, an electroabsorption optical modulator, a sine-wave voltage generator, a nonlinear circuit, and a DC voltage source. The single-wavelength light source outputs continuous, single-wavelength light. The electroabsorption optical modulator receives the single-wavelength light, modulates the single-wavelength light according to a pulse modulation signal, and outputs the modulated light as optical pulses. The sine-wave voltage generator generates an electrical signal having a sine waveform. The nonlinear circuit extracts only a waveform equal to or higher than a predetermined DC voltage from the sine waveform electrical signal. The DC voltage source adds a negative DC voltage to the electrical signal, from which only the waveform equal to or higher than the predetermined DC voltage is extracted by the nonlinear circuit, and applies the sum signal to the electroabsorption optical modulator as the pulse modulation signal.

The present invention relates to an optical pulse generation system and, more particularly, to a method and device for outputting optical pulses having high duty ratio, and an optical sampling pulse generation apparatus using the device.
Conventionally, as a device for generating high-duty optical pulses which have a repetition frequency ranging from several GHz to 10 GHz used in an optical communication system and a small pulse width, an optical pulse generation device using an electroabsorption optical modulator has been proposed, as shown in FIG. 14 (Jpn. Pat. Appln. KOKAI Publication No. 5-283804).
In this optical pulse generation device, for example, light a, which is a laser beam output from a single-wavelength light source 1 such as a laser beam source or the like, and has a continuous, single wavelength, becomes incident on the light entrance surface of an electroabsorption optical modulator 2.
The modulator electrode of this electroabsorption optical modulator 2 receives a pulse modulation signal c, which is obtained by adding a negative DC voltage Va output from a DC voltage source 4 to a sine-wave signal b output from a sine-wave generator 3.
The electroabsorption optical modulator 2 outputs, from its light exit surface, optical pulses d obtained by modulating the light a, which becomes incident on its light entrance surface and has a continuous, single wavelength, by the pulse modulation signal c input to its modulator electrode.
The electroabsorption optical modulator 2 has light absorption characteristics A shown in FIG. 15 with respect to a negatively applied DC voltage V.
A DC voltage V is plotted in a linear scale on the abscissa of the light absorption characteristics A, while the light intensity to be output is plotted in a logarithmic (decibel: dB) scale along the ordinate.
Hence, when the sine-wave signal b is applied to the modulator electrode of this electroabsorption optical modulator 2 at a bias point that has shifted in the negative direction by the negative DC voltage Va, as shown in FIG. 16A, optical pulses d shown in FIG. 16B are output from the light exit surface of this electroabsorption optical modulator 2.
More specifically, as the optical pulses d, pulses 5 that define a waveform in which minus portions of the sine-wave signal b are compressed and its plus portions are amplified in a linear scale appear at periods Ta of the sine-wave signal b, as shown in FIG. 16B.
The pulse width Ts of each pulse 5 that forms the optical pulses d output from the light exit surface of the electroabsorption optical modulator 2, i.e., from the optical pulse generation device is expressed by the width of a portion 3 dB below the top of that pulse 5.
The pulse width Ts of the portion 3 dB below is greatly smaller than the period Ta of the sine-wave signal b.
Hence, using the pulse modulation signal c obtained by adding the negative DC voltage Va to the sine-wave signal b, the high-duty optical pulses d having the pulse width Ts greatly smaller than the repetition period Ta can be obtained.
In recent years, in an optical communication system, the transfer rate of optical signals is increasing, and an optical pulse generation device capable of generating optical pulses d having a pulse width Ts still smaller than the repetition period Ta is required.
Such requirement is also adamant in an optical sampling pulse generation device that outputs optical sampling pulses used to sample light to be measured, which becomes incident on a light sampling unit in a light sampling waveform measurement apparatus.
Hence, since the pulse width Ts of the optical pulses generated by the optical pulse generation device shown in FIG. 14 depends on the period Ta of the sine-wave signal b, i.e., a frequency fA of the sine-wave signal, a pulse width still smaller than the repetition period Ta cannot be obtained.
To combat this problem, an optical pulse generation device shown in FIG. 17 has been proposed (Jpn. Pat. Appln. KOKAI Publication No. 9-133901).
This optical pulse generation device shown in FIG. 17 comprises a plurality of sine-wave generators 3a and 3b for outputting sine-wave signals b1 and b2 (see FIG. 18B; only b1 is illustrated) having different frequencies with respect to a sine-wave generator 3 for outputting a fundamental sine-wave signal b (see FIG. 18A having a frequency fA.
The sine-Wave signals b1 and b2 are respectively delayed a predetermined amount by delay circuits 6a and 6b, and the delayed signals are added to the fundamental sine-wave signal b, thus obtaining a pulse modulation signal c having sharp peaks, as shown in FIG. 18C.
By applying the pulse modulation signal c having sharp peaks to the modulator electrode of an electroabsorption optical modulator 2, the pulse width Ts alone can be shortened without changing the repetition period Ta of optical pulses d output from the light exit surface of this electroabsorption optical modulator 2.
Furthermore, conventionally, an optical pulse generation device using a rectangular wave signal shown in FIG. 19 has been proposed (Jpn. Pat. Appln. KOKAI Publication No. 5-283804).
In the optical pulse generation device shown in FIG. 19, light a output from a single-wavelength light source 1 is modulated into optical pulses d1 by a first electroabsorption optical modulator 2a, and is then modulated into optical pulses d2 by a second electroabsorption optical modulator 2b.
A rectangular wave signal e1 (FIG. 20A) output from a rectangular wave generator 7 is applied to the first electroabsorption optical modulator 2a.
On the other hand, a rectangular signal e2 (FIG. 20B), which is obtained by delaying the rectangular wave signal e1 output from the rectangular wave generator 7 a predetermined period of time by a delay circuit 8, is applied to the second electroabsorption optical modulator 2b.
As a result, optical pulses d2 output from the second electroabsorption optical modulator 2b include pulses 5 having a pulse width Ts corresponding to the overlapping time between the rectangular wave signals e1 and e2, as shown in FIG. 20C.
Hence, when a short overlapping time between the rectangular wave signals e1 and e2 is set by adjusting the delay time of the delay circuit 8, as shown in FIGS. 20A, 20B, and 20C, only the pulse width TS can be shortened without changing the repetition period Ta of the output optic al pulses d2.
However, the optical pulse generation devices shown in FIGS. 17 and 19 still suffer the following problems.
In the optical pulse generation device shown in FIG. 17, in order to obtain the pulse modulation signal c having sharp peaks shown in FIG. 18C, the delay amounts in delay circuits 6a and 6b must be set with high precision while synchronizing sine-wave generators 3, 3a, and 3b.
In this case, since the frequency of the sine-wave signal b is as very high as several GHz to 10 GHz, complicated setting adjustment is required to set the delay amounts with high precision, and the delay amount may vary soon even after they are set with high precision.
Furthermore, the optical pulse generation device shown in FIG. 17 requires a large number of sine-wave generators 3, 3a, and 3b, and delay circuits 6a and 6b, resulting in a complicated circuit arrangement.
In the optical pulse generation device shown in FIG. 19, since the repetition frequency of the rectangular wave signal e1 output from the rectangular wave generator 7 is as very high as several GHz to 10 GHz, jitter of around 1 ps is produced at the leading and trailing edges of the rectangular wave.
As a consequence, jitter of around 1 ps is produced in the optical pulses d2 output from this optical pulse generation device.
The jitter of around 1 ps is not negligible for optical pulses which are required to have a pulse width Ts of 3 to 4 ps.
Consequently, in this pulse generation device, decreasing the pulse width Ts of the output optical pulses d2 by setting a short overlapping time between the rectangular wave signals e1 and e2 is limited.
The present invention has been made in consideration of the above situation, and has as its object to provide a method and device for generating optical pulses, which can form a sharp peak waveform in a pulse modulation signal to be applied to an electroabsorption optical modulator by a simple circuit arrangement, and can still shorten only the pulse width compared to the repetition period of output optical pulses, and an optical sampling pulse generation apparatus using the device.
In order to achieve the above object, according to the present invention,
(1) there is provided an optical pulse generation method in which a pulse modulation signal is applied to an electroabsorption optical modulator while continuous, single-wavelength light is launched into the electroabsorption optical modulator so as to modulate the incoming single-wavelength light by the pulse modulation signal and to output the modulated light as optical pulses, comprising the steps of:
generating an electrical signal having a sine waveform;
extracting only a waveform not less than a predetermined DC voltage from the sine waveform of the electrical signal; and
adding a negative DC voltage to the extracted waveform, and applying the sum signal to the electroabsorption optical modulator as the pulse modulation signal.
In order to achieve the above object, according to the present invention,
(2) there is provided an optical pulse generation device comprising:
a single-wavelength light source for outputting continuous, single-wavelength light;
an electroabsorption optical modulator for receiving the single-wavelength light output from the single-wavelength light source, modulating the incoming single-wavelength light according to an externally applied pulse modulation signal, and outputting the modulated light as optical pulses;
a sine-wave voltage generator for generating an electrical signal having a sine waveform;
a nonlinear circuit for extracting only a waveform not less than a predetermined DC voltage from the sine waveform of the electrical signal generated by the sine-wave voltage generator; and
a DC voltage source for adding a negative DC voltage to the extracted waveform by the nonlinear circuit, and applying the sum signal to the electroabsorption optical modulator as the pulse modulation signal.
In order to achieve the above object, according to the present invention,
(3) there is provided an optical pulse generation device according to (2), wherein the nonlinear circuit comprises:
a half-wave rectification circuit for outputting a half-wave rectified signal of the electrical signal having the sine waveform, which is output from the sine-wave voltage generator; and
a voltage amplifier for voltage-amplifying the half-wave rectified signal output from the half-wave rectification circuit.
In order to achieve the above object, according to the present invention,
(4) there is provided an optical pulse generation device according to (2), wherein the nonlinear circuit comprises a voltage amplifier, an operation point of which can be shifted, and voltage-amplifies the electrical signal having the sine waveform output from the sine-wave voltage generator while the operation point is shifted in a negative direction.
In order to achieve the above object, according to the present invention,
(5) there is provided an optical pulse generation device comprising:
a single-wavelength light source for outputting continuous, single-wavelength light;
a first electroabsorption optical modulator for receiving the single-wavelength light output from the single-wavelength light source, modulating the incoming single-wavelength light according to an externally applied pulse modulation signal, and outputting the modulated light as optical pulses;
a first modulation signal generation circuit comprising:
a) a sine-wave voltage generator for generating an electrical signal having a sine waveform,
b) a nonlinear circuit for extracting only a waveform not less than a predetermined DC voltage from the sine waveform of the electrical signal generated by the sine-wave voltage generator, and
c) a DC voltage source for adding a negative DC voltage to the extracted waveform by the nonlinear circuit, and applying the sum signal to the first electroabsorption optical modulator as the pulse modulation signal;
a second electroabsorption optical modulator for receiving the optical pulses output from the first electroabsorption optical modulator, modulating the incoming optical pulses according to an externally applied pulse modulation signal, and outputting the modulated optical pulses as final optical pulses; and
a second modulation signal generation circuit comprising:
a) a DC voltage source for outputting a negative DC voltage,
b) a rectangular wave signal generation circuit for outputting a rectangular wave signal, and
c) a sync adjustment circuit,
the second modulation signal generation circuit synchronously adjusting the rectangular wave signal output from the rectangular wave signal generation circuit by the sync adjustment circuit to make individual rectangular waves of the rectangular wave signals include optical pulses once every predetermined number of pulses, adding the negative DC voltage output from the DC voltage source to the adjusted rectangular wave signal, and applying the sum signal to the second electroabsorption optical modulator as the pulse modulation signal.
In order to achieve the above object, according to the present invention,
(6) there is provided an optical pulse generation device comprising:
a single-wavelength light source for outputting continuous, single-wavelength light;
an electroabsorption optical modulator for receiving the single-wavelength light output from the single-wavelength light source, modulating the incoming single-wavelength light according to an externally applied pulse modulation signal, and outputting the modulated light as optical pulses;
a modulation signal generation circuit comprising:
a) a sine-wave voltage generator for generating an electrical signal having a sine waveform,
b) a nonlinear circuit for extracting only a waveform not less than a predetermined DC voltage from the sine waveform of the electrical signal generated by the sine-wave voltage generator, and
c) a DC voltage source for adding a negative DC voltage to the extracted waveform by the nonlinear circuit, and applying the sum signal to the electroabsorption optical modulator as the pulse modulation signal; and
a dispersion decreasing fiber for receiving the optical pulses output from the electroabsorption optical modulator at one end, and outputting the incoming optical pulses as final optical pulses from the other end.
In order to achieve the above object, according to the present invention,
(7) there is provided an optical sampling pulse generation device for outputting optical sampling pulses used to sample light to be measured, which enters a light sampling unit in a light sampling waveform measurement apparatus, comprising:
a single-wavelength light source for outputting continuous, single-wavelength light;
a first electroabsorption optical modulator for receiving the single-wavelength light output from the single-wavelength light source, modulating the incoming single-wavelength light according to an externally applied pulse modulation signal, and outputting the modulated light as optical pulses;
a first modulation signal generation circuit comprising:
a) a nonlinear circuit for extracting only a waveform not less than a predetermined DC voltage from an electrical signal having a sine waveform, and
b) a DC voltage source for adding a negative DC voltage to the extracted waveform by the nonlinear circuit, and applying the sum signal to the first electroabsorption optical modulator as the pulse modulation signal;
a second electroabsorption optical modulator for receiving the optical pulses output from the first electroabsorption optical modulator, modulating the incoming optical pulses according to an externally applied pulse modulation signal, and outputting the modulated optical pulses as final optical pulses; and
a second modulation signal generation circuit comprising:
a) a DC voltage source for outputting a negative DC voltage,
b) a rectangular wave signal generation circuit for outputting a rectangular wave signal, and
c) a sync adjustment circuit,
the second modulation signal generation circuit synchronously adjusting the rectangular wave signal output from the rectangular wave signal generation circuit by the sync adjustment circuit to make individual rectangular waves of the rectangular wave signals include optical pulses once every predetermined number of pulses, adding the negative DC voltage output from the DC voltage source to the adjusted rectangular wave signal, and applying the sum signal to the second electroabsorption optical modulator as the pulse modulation signal;
a dispersion decreasing fiber for receiving the optical pulses output from the second electroabsorption optical modulator at one end, and outputting the incoming optical pulses as final optical pulses from the other end;
a timing clock generation circuit for supplying a first sampling clock signal which is delayed a predetermined time from a clock signal based on a repetition period of the light to be measured to the nonlinear circuit of the first modulation signal generation circuit as the electrical signal having the sine waveform; and
a frequency divider for supplying a second sampling clock signal which is obtained by frequency-dividing the first sampling clock signal from the timing clock generation circuit at a predetermined ratio to the sync adjustment circuit of the second modulation signal generation circuit.
Invention above is applied to an optical pulse generation method in which a pulse modulation signal is applied to an electroabsorption optical modulator while continuous, single-wavelength light becomes incident on the electroabsorption optical modulator to modulate the incoming single-wavelength light by the pulse modulation signal, thus outputting the modulated light as optical pulses.
In order to achieve the above object, in invention (1), an electrical signal having a sine waveform is generated, only a waveform equal to or higher than a predetermined DC voltage is extracted from the sine waveform of the electrical signal, a negative DC voltage is added to the extracted waveform, and the sum signal is then applied to the electroabsorption optical modulator as the pulse modulation signal.
The optical pulse generation device according to invention (2) above comprises a single-wavelength light source for outputting continuous, single-wavelength light, an electroabsorption optical modulator for receiving the single-wavelength light output from the single-wavelength light source, modulating the incoming single-wavelength light on the basis of an externally applied pulse modulation signal, and outputting the modulated light as optical pulses, a sine-wave voltage generator for generating an electrical signal having a sine waveform, a nonlinear circuit for extracting only a waveform not less than a predetermined DC voltage from the sine waveform of the electrical signal generated by the sine-wave voltage generator, and a DC voltage source for adding a negative DC voltage to the extracted waveform by the nonlinear circuit, and applying the sum signal to the electroabsorption optical modulator as the pulse modulation signal.
In the optical pulse generation device with this arrangement, the electrical signal output from the sine-wave voltage generator is rectified and amplified by extracting only the waveform equal to or higher than the predetermined DC voltage from its sine waveform.
That is, the electrical signal is sliced at an arbitrary signal level including the waveform center of half-wave rectification in a sine-wave signal waveform, and the sliced waveform portion is amplified.
Hence, substantially the same effect as in the optical pulse generation method of invention (1) can be obtained.
In the optical pulse generation method and device with the above arrangement, the pulse modulation signal applied to the electroabsorption optical modulator is the sum signal obtained by extracting only the waveform equal to or higher than the predetermined DC voltage from the sine waveform of the electrical signal, and adding the negative DC voltage to the extracted waveform
In the optical pulse generation device according to invention (3) above, in invention (2), the nonlinear circuit comprises a half-wave rectification circuit for outputting a half-wave rectified signal of the electrical signal having the sine waveform, which is output from the sine-wave voltage generator, and a voltage amplifier for voltage-amplifying the half-wave rectified signal output from the half-wave rectification circuit.
In the optical pulse generation device with this arrangement, the pulse modulation signal applied to the electroabsorption optical modulator is the sum signal obtained by amplifying the half-wave rectified signal by the amplifier, and adding the negative DC voltage to the amplified half-wave rectified signal.
In this case, the voltage value of the pulse modulation signal applied to the electroabsorption optical modulator inevitably has an upper limit value.
Since the bias point in light absorption characteristics A shown in FIG. 15 is also limited, the amplitude value (Pxe2x80x94P) of the amplified half-wave rectified signal to be added to the negative DC voltage VA is limited.
The waveforms of the respective signals when the amplitude value (Pxe2x80x94P) of the half-wave rectified signal is equal to that of the sine-wave signal before half-wave rectification are compared.
Of these signals, the half-wave rectified signal waveform is obtained by extracting only positive portions of the sine-wave signal waveform.
Hence, when the amplitude values (Pxe2x80x94P) are equal to each other, the half-wave rectified signal waveform is elongated in the vertical direction compared to the sine-wave signal waveform.
As a result, the half-wave rectified signal waveform defines a sharp peak waveform that has larger changes in voltage per unit time than the sine-wave signal waveform.
Hence, the pulse width Ts of modulated optical pulses output from the electroabsorption optical modulator can be greatly smaller than that of conventional optical pulses modulated using the sine-wave signal.
Note that the repetition period Ta of optical pulses is determined by the frequency fA of the sine-wave signal before half-wave rectification, and is not shortened.
Therefore, only the pulse width Ts can be further shortened compared to the repetition period Ta of optical pulses output from the electroabsorption optical modulator.
In the optical pulse generation device with this arrangement, an electrical signal output from the sine-wave voltage generator is rectified and amplified by extracting only a waveform equal to or higher than a predetermined DC voltage from the sine waveform of that electrical signal. That is, the electrical signal is sliced at an arbitrary signal level including the waveform center of half-wave rectification of claim 2 in a sine-wave signal waveform, and the sliced waveform portion is amplified. Hence, substantially the same effect as in the optical pulse generation method of invention can be obtained.
In the optical pulse generation device according to invention (4) above, in invention (2), the nonlinear circuit comprises a voltage amplifier, an operation point of which can be shifted, and voltage-amplifies the electrical signal having the sine waveform output from the sine-wave voltage generator while the operation point is shifted in a negative direction.
That is, this optical pulse generation device comprises a single-wavelength light source for outputting continuous, single-wavelength light, an electroabsorption optical modulator for receiving the single-wavelength light output from the single-wavelength light source, modulating the incoming single-wavelength light on the basis of an externally applied pulse modulation signal, and outputting the modulated light as an optical pulse, and a modulation signal generation circuit which comprises a DC voltage source for outputting a negative DC voltage, a sine-wave generation circuit for outputting a sine-wave signal, and a voltage amplifier whose operation point can be shifted, amplifies the sine-wave signal by the voltage amplifier while the operation point is shifted in the negative direction, adds the negative DC voltage to the amplified sine-wave signal, and applies the sum signal to the electroabsorption optical modulator as the pulse modulation signal.
The voltage amplifier whose operation point can be shifted is assembled in the optical pulse generation device with this arrangement. The sine-wave signal is amplified by that voltage amplifier while the operation point is shifted in the negative direction.
Hence, the amplified sine-wave signal has a waveform obtained by cutting off some minus components.
As a result, the amplified sine-wave signal is approximated to the amplified half-wave rectified signal.
At this time, when the amplitude value (Pxe2x80x94P) of the amplified signal is constant, since the amplified sine-wave signal has a sharp peak waveform having a larger change in voltage per unit time, as described above, nearly the same effect as in the above inventions can be obtained.
An optical pulse generation device according to invention (5) comprises a single-wavelength light source for outputting continuous, single-wavelength light, a first electroabsorption optical modulator for receiving the single-wavelength light output from the single-wavelength light source, modulating the incoming single-wavelength light on the basis of an externally applied pulse modulation signal, and outputting the modulated light as an optical pulse, a first modulation signal generation circuit which substantially comprises a DC voltage source for outputting a negative DC voltage, a half-wave rectification circuit for outputting a half-wave rectified signal, and a voltage amplifier, amplifies the half-wave rectified signal by the voltage amplifier, adds the negative DC voltage to the amplified half-wave rectified signal, and applies the sum signal to the first electroabsorption optical modulator as the pulse modulation signal, a second electroabsorption optical modulator for receiving optical pulses output from the first electroabsorption optical modulator, modulating the incoming optical pulses on the basis of an externally applied pulse modulation signal, and outputting the modulated optical pulses as final optical pulses, and a second modulation signal generation circuit which comprises a DC voltage source for outputting a negative DC voltage, a rectangular wave signal generation circuit for outputting a rectangular wave signal, and a sync adjustment circuit, synchronously adjusts the rectangular wave signal output from the rectangular wave signal generation circuit using the sync adjustment circuit so that individual rectangular waves of the rectangular wave signal include optical pulses once every predetermined number of pulses, adds the negative DC voltage to the adjusted rectangular wave signal, and applies the sum signal to the second electroabsorption optical modulator as the pulse modulation signal.
In the optical pulse generation device with this arrangement, light output from the single-wavelength light source is modulated by the first electroabsorption optical modulator to obtain optical pulses, and these optical pulses are further modulated by the second electroabsorption optical modulator to obtain final optical pulses.
Since the first modulation signal generation circuit having the same arrangement as that of the modulation signal generation circuit of claim 2 is connected to the first electroabsorption optical modulator, optical pulses output from the first electroabsorption optical modulator have a small pulse width Ts.
Since the pulse modulation signal of the rectangular wave signal, that includes optical pulses once every predetermined number of pulses is applied to the second electroabsorption optical modulator, the optical pulses output from the first electroabsorption optical modulator are output once every predetermined number of pulses by decimation.
As a consequence, the repetition period Ta of pulses is prolonged. However, since the pulse width Ts of each pulse of the optical pulses remains the same, the pulse width Ts can be still shortened compared to the pulse repetition period Ta.
An optical pulse generation device according to invention (6) comprises a single-wavelength light source for outputting continuous, single-wavelength light, an electroabsorption optical modulator for receiving the single-wavelength light output from the single-wavelength light source, modulating the incoming single-wavelength light on the basis of an externally applied pulse modulation signal, and outputting the modulated light as an optical pulse, a modulation signal generation circuit which substantially comprises a DC voltage source for outputting a negative DC voltage, a half-wave rectification circuit for outputting a half-wave rectified signal, and a voltage amplifier, amplifies the half-wave rectified signal by the voltage amplifier, adds the negative DC voltage to the amplified half-wave rectified signal, and applies the sum signal to the electroabsorption optical modulator as the pulse modulation signal, and a dispersion decreasing fiber for receiving optical pulses output from the electroabsorption optical modulator at one end, and outputting the incoming optical pulses as final optical pulses from the other end.
In the optical pulse generation device with this arrangement, the dispersion decreasing fiber is further connected to the optical pulse generation device according to invention (2) above.
The dispersion decreasing fiber has characteristics in which the wavelength dispersion of light input from one end decreases with increasing distance if a predetermined wavelength condition and an optical fiber length condition (soliton condition) are satisfied, as is well known.
As a result, the pulse width Ts of optical pulses output from the other end is further shortened.
An optical sampling pulse generation apparatus according to invention (7) has the arrangements of the optical pulse generation devices according to inventions (5), (6) and their features, and also has an arrangement unique to an optical sampling pulse generation apparatus serving as a light sampling waveform measurement apparatus and their features.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.

Optical pulse generation system for generating optical pulses having high duty ratio


An apparatus and method is discloses for providing a substantially uniform, homogenous, polarized light. A beam of substantially un-polarized light is provided by a conventional light source. The un-polarized light is converted to at least four real images by using a light pipe and appropriate lensing. Each of the real images have a light region and one more dark regions at a first image plane. A portion of light from a light region in each real image is directed to one or more dark regions in each of the real images in a polarization dependent manner and the altered image is into a single image of substantially polarized light.

In projection display systems the function of the illumination system is to provide uniform illumination to a spatial light modulator (SLM). Typically the illumination system in a projection display consists of a light source such an arc lamp or light emitting diodes (LEDs), a homogenizer of some type for providing homogenized light at the SLM, and a relay lens for providing a beam having a desired size, shape and telecenetricity.
In some projection display systems, liquid crystal spatial light modulators are used, and it is desirable to illuminate such modulators with polarized light. A polarizer can be added to the illumination system to filter the light, so as to provide a polarized beam to the SLM, however this method has an associated loss of 50% of the light, as one polarization state is absorbed or otherwise lost. Illumination systems utilizing polarization recovery techniques seek to take this lost light and covert it to the desired polarization state so it can be recovered and utilized, thus increasing the efficiency of the system and hence the brightness of projection. Prior art methods of performing this polarization recovery and conversion include the use of lenslet arrays and a polarization conversion array (PCA) or the use of a polarization converting light pipe (PCLP).
Projection displays incorporating transmissive liquid crystal SLMs typically use a lenslet array and a PCA; some reflective liquid crystals SLMs also known as liquid crystal on silicon (LCoS) also use a lenslet array and PCA. Prior art FIG. 1 of the accompanying drawings is a schematic view of the essential portions of another liquid crystal projector disclosed in U.S. Pat. No. 6,139,157. In FIG. 1, light emitted by a lamp 201a is reflected toward an image display element 207 by a reflector 203, and enters a first lens array 201b comprising a plurality of lenses arranged into the form of a grating. The aforementioned light is condensed near the lenses of a second lens array 202 similar in construction to the first lens array 201 and comprising lenses having the same degree of focal length as the interval between the first lens array 201 and the second lens array 202 and arranged into the form of a grating by the lenses of the first lens array 201, and is caused to be transmitted through the lenses of the second lens array 202, whereafter it enters a polarization converting element 204.
The light beam which has entered the polarization converting element 204 is separated into different polarized components (S component and P component) by a polarization separating surface 204a, and S-polarized light reflected by the polarization separating surface 204a is reflected by a reflecting mirror 204b and is transmitted through a half wavelength plate 205, whereby it is converted into the same polarized state as the P-polarized light transmitted through the polarization separating surface 204a.
P-polarized light beams having the same directions of polarization which have emerged from the polarization converting element 204 illuminate the image display element 207 provided near the focus position (the surface to be irradiated) of a condensing lens 206, through the condensing lens 206. An image displayed by the image display element 207 is projected onto a predetermined surface by a projection lens.
On the other hand, the liquid crystal projector shown in FIG. 1 forms a plurality of secondary light source images by a the fly-eye type optical integrator and superposes the light beams from the plurality of secondary light source images one upon another on the surface to be irradiated to uniformly illuminate the surface 207 to be irradiated.
The liquid crystal projector of FIG. 1, however, requires first and second lens arrays of the same degree of size as an opening in the reflecting mirror 203 and therefore, the entire apparatus tends to be bulky.
There have heretofore been proposed various liquid crystal projectors for illuminating a liquid crystal panel by a light beam from a light source, and enlarging and projecting image light such as transmitted light or reflected light from the liquid crystal panel onto a screen or a wall by a projection lens.
Usually the liquid crystal panel utilizes the polarizing characteristic of liquid crystal. Therefore, usually, polarizing filters such as a polarizer and an analyzer are provided before and behind the liquid crystal panel. The polarizing filter has the characteristic of transmitting therethrough polarized light polarized in a particular direction of polarization of incident light, and intercepting polarized light of which the direction of polarization is orthogonal thereto. Therefore, the light from the light source utilized in the liquid crystal projector has had at least a half thereof intercepted by the polarizer which is a polarizing filter and thus, the brightness of the image projected onto the screen or the wall has not been sufficient.
Projection systems being manufactured incorporating LCos SLMs currently employ PCLPs in their illumination system. The most common form of PCLP includes a reflector in the form of a light pipe having two PBSs at the input end of the light pipe. Light from the light source is incident upon one PBS. The PBS spits the light into S and P polarization states. P-polarized light is transmitted and the S-polarized light is reflected. The P-polarized light is then incident upon a rotator in the form of a half-wave retarder which is oriented such that the emerging light has its polarization axis rotated by 90 degrees such that it has been converted to S-polarized light. The S-polarized light split off by the PBS is then incident upon the second PBS where it is reflected and re-directed into the light pipe. S-polarized light thus emerges from both PBSs and is then homogenized by the light pipe. The PCLP tends to be a lower cost system than the aforementioned lenslet array PCA, but suffers from lower contrast, approximately 6:1 emerging from the PCLP as compared with the 20 to 30:1 from the lenslet array PCA, and lower efficiency; about 72% compared with approximately 80%.
Prior art U.S. Pat. No. 6,139,157 incorporated herein by reference is directed to an illuminating apparatus which appears to have several elements in common with the instant invention. A light source, light pipe, lenses, a reflective polarization beam splitter, a polarization conversion element and a target plane are all shown in this patent. Notwithstanding, the invention shown in FIG. 13 of this patent, shown herein as FIG. 2, is absent an obstruction or opaque region at an input end of the light pipe. The applicant believes that by not providing a light pipe with masked region at the input end, a uniform polarized beam will not result. By providing the obstruction or masked region at an input end of the light pipe, and ensuring that the polarization translation and separation occurs at predetermined locations in dependence upon the configuration of the masked region, a desired uniform polarized beam will result. The description of FIG. 13 is as follows:
"The polarization converting element 74 shown in FIG. 13 uses a transparent plate provided with a polarization separating surface 701 on the surface thereof as reflecting means for bending the optical path by 90.degree. and a reflecting mirror 702 on the back thereof, and the optical paths of S-polarized light reflected by the surface and P-polarized light reflected by the back are deviated in parallelism to each other, and a half wavelength plate 703 is disposed on the optical path of the S-polarized light reflected by the surface (or the optical path of the P-polarized light reflected by the back) to thereby uniformize the directions of polarization of the two lights."
Also, in the system of prior art FIG. 13, half wavelength plates 703 are periodically provided on the flat surface of the plano-convex integrated lens 5 to thereby convert the direction of polarization of the incident S-polarized light into the same direction as the P-polarized light."
It is unclear whether the structure shown in FIG. 13 functions as it is intended to. Since there is no structure taught which blocks light from the input end, it would appear as if all light of one linear polarization incident upon surface 701 is reflected upon the entire receiving surface of 5. It would also appear as if all light reflected from surface 702 is reflected upon the same region of 5. Therefore it is not clear how this embodiment works to selectively rotate one linear polarization and not the other.
It is an object of this invention to provide a system and method for uniformly illuminating a spatial light modulator which incorporates a novel, relatively low cost method of polarization recovery.
It is an object of this invention to provide a simple, low cost system for providing substantially uniform polarized light for use in a projection display system.

Illumination system using polarization conversion


A developer collecting device includes a suction duct, a collecting box, and a suction mechanism. The suction duct has one end adjacent to a development device and another end. The collecting box is connected to the other end and configured to suction and collect developer around the development device via the suction duct. The suction mechanism is disposed in the middle of the suction duct. The suction mechanism includes a suction port that is openable and closable. The suction mechanism is configured to suction the developer inside the suction duct from an outside of the suction duct.

Unless otherwise indicated herein, the description in this section is not prior art to the claims in this application and is not admitted to be prior art by inclusion in this section.
There is known a developer collecting device that suctions and collects toner particles (developer) scattered in a development device in an image forming apparatus. This developer collecting device includes a toner suction duct, in which a suction port is located adjacent to the development device, and a toner collecting part, which is connected to the toner suction duct and suctions and collects the toner particles scattered in the development device via the toner suction duct.

Developer collecting device for suppressing decrease of developer collection rate and image forming apparatus


Method of coating woven fabric with a first latex compound having a viscosity of 18,000 to 20,000 cps, and containing a fire resistant additive. Then coating with a second latex compound to produce a hose ducting fabric which is fire resistant. The second latex compound preferably contains a fire resistant additive also, and may be of a viscosity between 20,000-30,000 cps.

In flexible ducts, a fabric or film is secured to a helical wire. The fabric can be secured by adhesives, crimping or sewing. The ducts are typically used to exhaust gases and vapors from a confined working area, i.e. the holds of ships, below ground electrical conduits, etc. The ducts must be flexible, extendable, collapsible, gas impermeable, fire resistant and abrasion resistant. The fabric which is secured to the steel wire primarily affects all these characteristics.
The fabric customarily used for duct material is a woven or non-woven material which is saturated and/or coated. The fabrics that are particularly used for this purpose are square woven, oxford or duck. These fabrics, when coated, result in a duct with poor flexibility, poor elongation rates and limited compressibility. Attempts to modify the coatings to improve these characteristics result in decreased resistance to wear (abrasion) and lower fire resistance.
The present invention overcomes these problems by using a fabric of a particular weave in combination with saturation and coating techniques and the components used, to provide a duct fabric of superior flexibility, collapsibility, elongation, fire resistance and abrasion resistance.
Broadly the invention comprises a duct fabric which comprises a woven twill fabric saturated with a latex-based, fire resistant compound at a first lower viscosity and coated with a second higher viscosity, latex-based, fire resistance compound compatible with the first lower viscosity compound. The fabric of the invention allows controlled elongation up to 55% in the warp direction and up to 22% in the filling direction. It also provides increased flexibility, compression, high abrasion resistance, and fire resistance.

Method of coating with multiple layers of latex to produce fire resistant hose ducting fabric


A circuit arrangement is provided, including a storage circuit and an output circuit. The storage circuit is configured to provide a first output signal and a second output signal. The output circuit is configured to receive the first output signal and the second output signal and configured to provide an output signal having one of a first signal level and a second signal level, and to only switch from the first signal level to the second signal level if the difference between the first output signal and the second output signal exceeds a threshold. The circuit arrangement is configured to hold the first output signal and the second output signal independent of a difference between the first output signal and the second output signal after the switching has been carried out.

An input of a circuit may for example be derived from an analog sensor signal. The analog sensor may indicate the occurrence of an event, for example, that a current has crossed a threshold. The occurrence of the event may be stored in a memory element and may be further processed afterwards. Such a circuit may be called an event catcher.
However, the shape and the timing of the signal at the input of the circuit may be uncertain. It is therefore possible that the timing conditions such as the setup time, hold time, minimum pulse width, etc. of the memory element may be violated and that the occurrence of an event is not recorded properly.
If the timing conditions of a memory element are violated it may stay in a metastable state for an uncertain time before it will toggle into one of its stable states. The stable state into which the memory element will toggle is also unpredictable. A metastable state may propagate to other parts of the circuit and may result in undefined behavior. As an example, this may occur in mixed-signal processing, where outputs of analog components are processed by a clocked digital logic and where the control logic of the analog components is not synchronized with the signal clock of the digital logic.

Circuit arrangement and method for operating a circuit arrangement


Toner compositions comprise (a) a toner particulate including resin, magnetic component and charge control agent, and (b) an extra-particulate additive comprising a first hydrophobic additive having negative tribocharging properties and a second hydrophobic additive having positive tribocharging properties.

Numerous methods and apparatus for electrophotography, electrostatic recording and electrostatic printing are known in the art. Typically, a charged photosensitive surface, for example a charged photosensitive drum, is irradiated with an optical image and an electrostatic latent image is formed on the photosensitive surface. In the development process, a developing agent, i.e., toner, is adhered to the electrostatic latent image. Typically, a controlled amount of toner is fed to a developer magnetic roller by a metering blade positioned against the surface of the developing roller. The developer magnetic roller, with the toner on its surface, is typically rotated in a direction opposite to that of the photosensitive drum, and toner adheres to the electrostatic latent image to develop the image. Various toner compositions have been developed in order to provide improved copying, recording and/or printing with such apparatus.
In recent years, there has been a desire to recycle or remanufacture components of commercially available electrostatic copiers, recording devices and printers and particularly to recycle or remanufacture developer cartridges. Generally, the developer cartridges comprise a container for holding toner, a developer magnetic roller and a metering blade for applying an even layer of toner to the roller, and the cartridges are recycled by refilling the container with toner. Oftentimes, the developer magnetic roller in a recycled or remanufactured developer cartridge is worn to some extent so that the surface becomes relatively smooth and/or not sufficiently conductive. Consequently, toner is prevented from moving smoothly and uniformly through the metering blade nip and as a result, "wavy" patterns of toner may form on the developer roller which, in turn, are developed onto the photoconductive drum. Additionally, in some instances, the developer magnetic roller in a recycled or remanufactured developer cartridge is provided with a polymer-based coating to prevent further wear. Typically, the polymer coating which is applied to the developer roller does not have the same properties as the original developer roller surface so that the surface roughness and/or resistivity are altered. As a result, the layer of toner carried on the developer roller will have irregularities which in turn will be evident in the image developed on the photoconductive drum.
Recoated or worn developer magnetic rollers also may exhibit higher resistivities than new developer rollers. As a result, the charge of a layer of toner on the developer roller may be increased as voltage bleed off is prevented. This in turn results in a thin layer of very highly charged toner particles which stick to the recoated or worn developer roller and do not develop onto the drum. The developer roller continues to pick up toner from the hopper; however, the toner is much lower in charge because there is not sufficiently good contact between the second layer of toner and the surface of the developer roller. Consequently, the low charged toner builds up on top of the highly charged toner and creates a wavy pattern on the surface after going through the metering blade nip. Because the second layer of toner is not highly charged, it readily develops onto the drum and then transfers to paper as the aforementioned "wavy" defects.
While many toner compositions are designed for good development in new OEM equipment, oftentimes commercially available toner compositions cannot accommodate the irregularities in the development process caused by recycled or remanufactured developer equipment such as developer cartridges. Accordingly, a need exists for toner compositions which not only provide good development in new electrostatic copying, recording and printing apparatus but are also capable of providing good development when employed in recycled or remanufactured developer cartridges in such apparatus.
Typically, extra-particulate additives are combined with toner particulates in order to improve selected properties of the toner particulates including transferability, cleaning properties, flowability and the like, as taught, for example, in the Akagi et al U.S. Pat. No. 5,296,324 and the Kanbayashi et al U.S. Pat. No. 5,120,631. It has also been suggested to lower the chargeability (tribocharge) of toner compositions in order to improve transferability, cleaning properties, flow problems and the like. However, print quality problems, including low optical density and high CAD, often result. Accordingly, there is a continuing need for improving toner compositions.

Toner composition including positive and negative tribocharging hydrophobic extra-particulate additives