The present invention discloses simple and yet highly efficient configurations of optical coherence domain reflectometry systems. The combined use of a polarizing beam splitter with one or two polarization manipulator(s) that rotate the returned light wave polarization to an orthogonal direction, enables one to achieve high optical power delivery efficiency as well as fixed or predetermined output polarization state of the interfering light waves reaching a detector or detector array, which is especially beneficial for spectral domain optical coherence tomography. In addition, the system can be made insensitive to polarization fading resulting from the birefringence change in the sample and reference arms. Dispersion matching can also be easily achieved between the sample and the reference arm for high resolution longitudinal scanning.

1. Field of the Invention
The invention relates generally to optical imaging and in particular to systems and methods for achieving flexibility in interference fringe visibility control and optimization of signal to noise ratio, as well as for achieving polarization insensitivity, dispersion matching and optical output polarization control in optical coherence domain reflectometry (OCDR) or optical coherence tomography (OCT).
2. Description of Related Art
Optical coherence domain reflectometry (OCDR) is a technique initially developed to provide a higher resolution over optical time domain reflectometry (OTDR) for the characterization of the position and the magnitude of reflection sites in such optical assemblies as optical fiber based systems, miniature optical components and integrated optics (Youngquist et al., "Optical Coherence-Domain Reflectometry: A New Optical Evaluation Technique", 1987, Optics Letters 12(3):158–160). With the addition of transverse scanning, this technique has been widely and successfully extended to the imaging of biological tissues, and is termed optical coherence tomography (OCT) (Huang, D., E. A. Swanson, et al. (1991). "Optical coherence tomography." Science 254 1178–81; and U.S. Pat. Nos. 5,321,501 and 5,459,570). Since then, a large number of applications have been found for this technology as evidenced by a number of review articles (Swanson E. A. et al. "Optical coherence tomography, Principles, instrumentation, and biological applications" Biomedical Optical Instrumentation and Laser-Assisted Biotechnology, A. M. Verga Scheggi et al. (eds.) pages: 291–303, 1996 Kluwer Academic Publishers, Printed in the Netherlands; Schmitt, J. M. "Optical coherence tomography (OCT): a review" IEEE Journal of Selected Topics in Quantum Electronics, Volume: 5, Issue: 4, Year: July/August 1999, pages: 1205–1215; Fujimoto, J. G. et al. "Optical Coherence Tomography: An Emerging Technology for Biomedical Imaging and Optical Biopsy" Neoplasia (2000) 2, 9–25; Rollins A. M. et al. "Emerging Clinical Applications of Optical Coherence Tomography" Optics and Photonics News, Volume 13, Issue 4, 36–41, April 2002; Fujimoto, J. G. "Optical coherence tomography for ultrahigh resolution in vivo imaging." Nat Biotechnol 21(11): 1361–7, (2003)). Each of these documents is incorporated herein by reference.
The most straightforward and most commonly used interferometer configuration for OCDR or OCT is a standard Michelson interferometer. As shown in FIG. 1, light from a low coherence source 110 is input into a beam splitter or 2×2 fiber optic coupler 112, where the light is split and directed into a sample arm 114 and a reference arm 116. An optical fiber 118 in the sample arm 114 extends into a device 120 that scans an object 122. The reference arm 116 provides a variable optical delay. Light input into the reference arm 116 is reflected back by a reference mirror 124. A piezoelectric modulator 126 may be included in the reference arm 116 with a fixed reference mirror 124, or the modulator 126 may be eliminated by scanning the mirror 124 in the Z-direction. The reflected reference beam from reference arm 116 and the scattered sample beam from sample arm 114 pass back through the coupler 112 to detector 128 (including processing electronics), which processes the signals by techniques that are known in the art to produce a backscatter profile or image on a display unit 130.
This configuration is advantageous in that it uses a minimum number of optical components and is hence the simplest. It can be implemented using bulk or fiber optics or a combination thereof. However, this configuration is limited to an optical efficiency of 25% as explained below.
By examining the configuration, it is not difficult to discover that the optical power reaching the detector from the two arms is reciprocal with respect to the beam splitter or fiber coupler (BS/FC). Assuming that the power split ratio of the beam splitter is
  α      1    -    α  and neglecting loss in the splitter, the attenuation by the beam splitter or the fiber coupler (BS/FC) to both the sample optical wave and the reference optical wave is the same and is equal to α(1−α), the only difference is that for one wave it will propagate straight-through the BS/FC first with an attenuation by a factor of α and then crossover the BS/FC with a further attenuation by a factor of (1−α), whereas for the other wave, it will crossover the BS/FC first with an attenuation by a factor of (1−α) and then propagate straight-through the BS/FC with a further attenuation by a factor of α. It is well known to those skilled in the art that for such a configuration, the most efficient power splitting ratio is 50/50, where
            α              1        -        α              =    1    ,simply because the function α(1−α) has its maximum value when α=0.5. For example, with a 50/50 power split ratio, for either the sample arm or the reference arm, the optical power is firstly attenuated at the BS/FC by 50% from the light source to the sample or reference arm and then further attenuated by 50% from the sample or reference arm to the detector, which leads to a total overall power attenuation factor of 50%×50%=25% for both arms. If the BS/FC power split ratio is 90/10, then for the reference and the sample arm respectively, the total overall power attenuation factor by the BS/FC will be 90%×10% and 10%×90%, which is the same and is equal to only 9%.
Various configurations have been proposed to improve the optical power efficiency. The configuration described in this patent is simpler than those previously proposed designs and also addresses polarization fading issues that are not addressed by the other high optical efficiency designs.
Rollins and Izatt (U.S. Pat. No. 6,657,727; Andrew M. Rollins, Joseph A. Izatt "Optimal interferometer designs for optical coherence tomography" Optics Letters, Vol. 24, Issue 21, Page 1484 (1999)) proposed a number of interferometer configurations to improve the optical efficiency of the above Michelson interferometer configuration. As shown in FIG. 2, a key optical element that is used in all their configurations is a commercially available non-reciprocal device called an optical circulator and such a circulator is combined with unbalanced couplers, and (or) balanced heterodyne detection for optical power efficient interferometer construction. In contrast, the design we describe herein eliminates the optical circulator, a complex and expensive component. Our design is also very compact and relatively low cost as it uses a minimum number of optical elements.
It should be pointed out that FIG. 2 encompasses six configurations, where the three insets (FIGS. 2Aii; 2Bii and 2Cii) basically show a modification from the three corresponding balanced heterodyne detection approach employing balanced couplers to a single detector based detection employing unbalanced coupler(s) as shown in the main FIGS. 2Ai; 2Bi and 2Ci. Refer now to the first two configurations (FIGS. 2Ai and 2Aii), which are based on a Mach-Zehnder interferometer with the sample 222 located in a sample arm 214 and the reference optical delay line (ODL) 225 in the reference arm 216. In the case of 2Ai, the main difference from a standard Mach-Zehnder interferometer is that the prior fiber coupler 212 has an optical power split ratio of
      α    1        1    -          α      1      instead of 50/50 that is optimized for optical power efficient high SNR detection by directing most of the original optical power to the sample arm 214 and meanwhile light is coupled to the sample 222 through an optical circulator 232 such that the backscattered optical signal is collected by the delivery fiber 218 but is redirected to the post fiber coupler 234. The reference arm ODL 225 may be transmissive using, for example, a fiber wrapped PZT based fiber stretcher or it may be retroreflective using, for example, a corner mirror or cube combined with another optical circulator (not shown, see U.S. Pat. No. 6,657,727). Note that in FIG. 2Ai, the post fiber coupler 234 has a split ratio of 50/50 and due to the employment of balanced heterodyne detection 236, Izatt and Rollin showed that the SNR of FIG. 2Ai can be improved over that of a standard Michelson configuration as shown in FIG. 1.
In the configuration of FIG. 2Aii, the post fiber coupler 238 is also made non-50/50 and a single detector 240 is used. The advantage of FIG. 2Aii embodiment as compared to FIG. 2Ai embodiment is that since only one detector is used, the cost of the system will be lower than that of FIG. 2Ai.
Refer now to FIGS. 2Bi and 2Bii, while the sample arm part is the same as in FIGS. 2Ai and 2Aii, the reference arm ODL 242 is made retroreflective but without the need of a second optical circulator. Again, the optical power split ratio of both the prior fiber coupler 244 and the post fiber coupler 246,
                    α        1                    1        -                  α          1                                            and                                        α        2                    1        -                  α          2                      ,can be properly chosen for either the two detector based balanced heterodyne detection case 248 or the unbalanced single detector case 250 to optimize the SNR such that the system is optical power efficient. Izatt and Rollin showed that the SNR improvement of the FIGS. 2Bi and 2Bii embodiment is very similar to that of FIGS. 2Ai and 2Aii embodiments. Note that there will be a small portion of the optical power from the reference ODL 242 being returned to the light source path.
The configurations of FIGS. 2Ci and 2Cii are basically Michelson interferometer based and their difference as compared to FIG. 1 is the use of an optical circulator 252 in between the light source 254 and the fiber coupler 256 to channel the returned light from the fiber coupler 256 initially propagating towards the light source 254 now completely to the detector, d2. While for balanced heterodyne detection, the optical power split ratio of the fiber coupler 256 must be made 50/50, it should be noted that for the case of a single detector unbalanced detection 258 (FIG. 2Cii), the optical power delivered to detector d2 from the sample arm 260 and the reference arm 262 can be made different or non-reciprocal since for detector d2, the sample optical signal will propagate straight-through the fiber coupler 256 twice and the reference optical signal will cross-over the fiber coupler 256 twice. As a result, the optical power delivery to detector d2 can be made efficient by properly selecting the fiber coupler optical power split ratio
      α          1      -      α        .Izatt and Rollin stated that for the configuration shown in FIGS. 2Ci, the SNR can be improved over that of FIG. 1 and although this configuration is not as power efficient as the other two, i.e. FIGS. 2Ai and 2Bi, its significant advantage is that it can be easily retrofitted with a circulator in the source arm and with a balanced receiver, with no need to disturb the rest of the system. As for FIG. 2Cii, the SNR improvement is similar to that of FIGS. 2Aii and 2Bii.
As an extension to all their configurations, Izatt and Rollin included, in their patent (U.S. Pat. No. 6,657,727), three more configurations as shown in FIG. 3 in which a transmissive sample is in the place of the circulator and the sample. They defined a transmissive sample as any sample illumination and collection geometry in which the illumination and collection optics occupy separate optical paths. Such designs have significant alignment issues and are not relevant to the invention being described where the illumination and collection optics occupy the same optical path.
As can be seen from the above-mentioned various configurations, the key advantage of these prior configurations lies in the improvement of the optical power delivery efficiency to the detector(s), by properly selecting an optical power split ratio
  α      1    -    α  (for either the prior and/or the post fiber coupler).
Another issue with the classic Michelson interferometer (FIG. 1) is that light from the reference arm is coupled back into the optical source, causing side effects that can impact the quality of the resulting image. Most of the configurations proposed by Izatt and Rollins address this issue as does the invention described herein. An issue not addressed by Izatt and Rollins configurations above is polarization fading, or loss of signal associated with mismatches between the polarization states of the light from the reference and sample arms. These mismatches are caused by birefringence and its fluctuations in the sample and reference arms, generally dominated by the birefringence in the optical fibers.
For a retraced light wave, placement of Faraday rotators at the ends of the fibers has been shown in the prior art to eliminate polarization fading due to the fiber optic components. FIG. 4 shows the approach of using two Faraday rotator mirrors at the end of the two arms of a standard Michelson fiber optic interferometer to eliminate polarization fading (Kersey, A. D. et al. "Polarization-insensitive fiber optic Michelson interferometer", Electronics Letters, Volume: 27, Issue: 6, pages: 518–520, (1991)). In this design, the Faraday rotator and mirror enable birefringence compensation in a retraced fiber path for both the sample arm and the reference arm. Although this design solved the problem of polarization fading, it did not address the issue of optical efficiency as the optical splitter configuration is the same as the standard Michelson interferometer configuration of FIG. 1. The invention described herein takes advantage of the polarization rotation caused by the Faraday rotators to increase the optical efficiency of the system by introducing a polarizing beam splitter in the source arm for coupling the light returning toward the source into a detector. This leads to an unbalanced optical efficiency assuming no birefringence in the sample and the use of a polarized source. An additional advantage of such a system is that the light being collected on the detector is linearly polarized, which is advantageous for spectral domain optical coherence tomography and reflectometry systems.
In spectral domain OCT systems, the light is dispersed by a diffraction grating and collected by an array of detectors. The efficiency of the diffraction grating is generally polarization dependent, and thus can be made most efficient for linearly polarized light. As will be elaborated later, the present invention can meet such a requirement.
In order to partially address the polarization fading problem, U.S. Pat. No. 6,564,089 by Izatt et al. mentioned the provision of a polarization compensation means such as a Faraday rotator on the side of the light emission of the optical probe on top of some of the interferometer configurations as discussed before with respect to FIG. 2. By doing so, the OCT can obtain a stabilized interference output regardless of the state of the bend of the sample arm. The inclusion of a Faraday rotator at the end of the sample arm optical probe only is particularly related to the application of OCT to endoscopic biological imaging in which the sample arm optical probe beam needs to be rotated to acquire cross sectional images of a tubular tissue and hence the birefringence property of the sample arm is very vulnerable to fluctuations. A drawback of such a system is the additional cost of the Faraday rotator and furthermore, while polarization compensation is provided for the sample arm, the same is not provided for the reference arm and as a result, there will be a mismatch in the birefringence as well as the dispersion properties between the two arms. Obviously, any birefringence fluctuation in the reference arm will still cause polarization fading and at the same time, the final output optical polarization of the configuration is not predetermined and hence is not suitable for spectral domain OCT which is polarization dependent.
In terms of addressing the polarization fading issue, besides using Faraday rotators, an alternative approach is to use polarization-maintaining (PM) fibers. In addition, a so-called polarization diversity receiver (PDR) scheme (Sorin, et al. "Polarization independent optical coherence-domain reflectometry" U.S. Pat. No. 5,202,745) can also be used. There are also combinations in which PM-fiber, polarization control optical elements and FRM are used (Everett M. et al. "Birefringence insensitive optical coherence domain reflectometry system" U.S. Pat. No. 6,385,358). PM fibers have several issues associated with their two orthogonal polarization axes, which make them undesirable for commercial OCDR or OCT applications. These include variable optical dispersion, difficulties in maintaining high polarization extinction in the connection between two PM-fibers or between a PM-fiber and a polarization optical component, and high cost.
FIG. 5 shows Sorin, et al.'s polarization independent optical coherence-domain reflectometry configuration (U.S. Pat. No. 5,202,745), where the light returning from the sample and reference arms is split into two orthogonal polarization modes with each mode being detected by a separate detector. In this design, a linear polarizer in the reference arm is adjusted to compensate for birefringence in the reference arm so as to equal signal powers on each detector in the detector arm in the absence of a signal from the test, or sample, arm. The problem with this approach is that the polarizer needs to be adjusted as the birefringence in the reference arm changes. As the birefringence in the non-PM reference arm fiber is strongly affected by temperature and stress, the system must be recalibrated with each use, and suffers from polarization drift during use.
An alternate design for a fiber optic polarization insensitive OCDR system with non-PM fiber in the sample arm has previously been described (Kobayashi et al, "Polarization-Independent Interferometric Optical-Time-Domain Reflectometer", 1991, J. Lightwave Tech. 9(5):623–628). The reference arm in this system consists of all PM optical fiber. As the two arms use different types of optical fibers, their dispersion properties are drastically different, which hence will lead to loss of resolution due to mismatched dispersion between the sample and reference arms. The system also requires a specialized 50/50 coupler.
U.S. Pat. No. 6,385,358 disclosed a hybrid system involving the use of PM fibers, non-PM fibers and Faraday rotators. An important feature in this patent is the use of a 22.5° Faraday rotator in the beam path to enable a double path rotation of the polarized beam returned from reference arm so that the beam is equally split into two orthogonal polarization modes to interfere with the two corresponding but not necessarily equally split components of the beam from the sample arm, which are then detected by two detectors. By summing the interference signal envelops from the two detectors, the final signal is made independent of the birefringence of the sample arm in a similar way as in the case of a polarization diversity receiver. In addition to polarization insensitivity, the dispersion property of the sample arm is also matched with that of the reference arm to eliminate the dispersion effects that degrade image resolution. Furthermore, arbitrary power split ration α/(1−α) fiber coupler is also used to enable high efficiency optical power delivery to the detector. Considering that for medical applications, the portion of the fiber optic interacting with the patient must be changed for hygienic reasons, a non-PM fiber is incorporated into the sample arm to accommodate a disposable section at the end of the sample arm that interacts with the sample. However, a major disadvantage of the disclosed designs is that the system configuration is not simple at all, as it involves length matched PM fiber and non-PM fiber between the sample and references arms, their splices or connections and the use of a relatively large number of various optical components such as (PM or non-PM) fiber coupler, free space polarization beam splitter (PBS), various Faraday rotators of different rotation angles, and two photodetectors. In the case of a 22.5° Faraday rotator which is placed between a single PM fiber and a single mode non-PM fiber, the light beam needs to be expanded from a first fiber, collimated, passed through the Faraday rotator, and then refocused into the other fiber. All of these make the system both quite complicated and also expensive.
Given the problems with the systems described above, there is obviously a need to combine the benefit of optical power delivery efficiency with polarization insensitivity as well as dispersion matching in a simply configuration that will lower the cost and enhance the performance. The present invention addresses the above-mentioned problems and significantly improves on the prior art systems by effectively achieving high optical power delivery efficiency, polarization insensitivity and also dispersion matching, in a more compact, more robust, and also less expensive manner.

Simple high efficiency optical coherence domain reflectometer design


An internal combustion engine includes a compression cylinder having an air inlet and outlet, a conduit extending from the compression cylinder air outlet, an expansion cylinder of larger diameter than the diameter of said compression cylinder and having an inlet and outlet, and a heat exchanger disposed in the conduit and having a first passageway for flowing compressed air from the compression cylinder outlet to the expansion cylinder inlet, the expansion cylinder outlet being in communication with a second passageway in the heat exchanger for flowing combustion exhaust gases from the expansion cylinder through the heat exchanger. The heat exchanger operates to heat the compressed air before entry into the expansion cylinder and to cool the exhaust gases before entry into an exhaust conduit in communication with the heat exchanger second passageway.

1. Field of the Invention
This invention relates to internal combustion engines and is directed more particularly to an engine exhibiting improved thermal efficiencies, and to an improved method for generating power.
2. Description of the Prior Art
It is known to improve thermal efficiency of a gas turbine engine by employing a regenerative heat exchanger which operates to extract heat from combustion exhaust gases and to use the extracted heat to raise the temperature of compressed air prior to its entering the combustion chamber.
The use of heat exchangers in internal combustion engines to obtain improved thermal efficiencies, similarly to the use and improvement in gas turbine engines, is difficult because of the cyclic nature of the engine operation and the limited space inside the internal combustion engine combustion cylinder. Providing a regenerative thermal mass to receive and store heat from the combustion exhaust gas during an exhaust stroke and applying the heat to the compressed air charge, or fuel-air mixture, at the end of the compression stroke is theoretically possible but difficult in practice because of the requirement of providing sufficient heat transfer area while limiting the heat storage mass to a size suitable for disposition in the combustion space.
It is further known that spark ignition engines typically exhibit lower efficiencies than diesel engines because of the limited compression ratios of spark ignition engines. However, spark ignition engines can be made to provide efficiencies equal to those of diesel engines by employing a "more-complete-expansion" cycle. In such a cycle, the effective compression ratio is set in the 8-12 range by timing the closing of the inlet valve, while the expansion ratio is maintained in the 16-20 range. The more-complete-expansion approach is known and is used in commercially available spark ignition engines.
It is still further known that using insulated cylinder walls to reduce heat loss from the combustion gas to the ambient. air increases the power output in the expansion process. However, using insulated materials on the cylinder walls also causes the air to be heated and the compression power to increase, which counteracts the power gain in the expansion process. Therefore, the net gain in power output of the engine is low.
There is thus a need for an internal combustion engine having therein heat transfer means for extracting heat from combustion exhaust gasses and applying that heat to compressed air, or fuel-air mixture, prior to the initiation of the combustion process.
There is further a need for such an engine wherein substantially complete expansion is experienced.
There is still further a need for such an engine having a low compression ratio and a low air temperature at the end of compression and a low peak cylinder pressure, such that fuels with low octane rating do not cause engine detonation, and heavy construction, as in diesel engines, is not required, and an engine so provided is of less weight than a conventional diesel engine.
There is still further a need for an internal combustion engine having therein insulation means to reduce heat loss from the combusted gas while not causing heating of the air charge during compression.
There is still further a need for a method for generating power, which method is more efficient than previous methods utilizing internal combustion engines.

Internal combustion engine and method for generating power


An electronic ballast has a resonant tank circuit that includes a tank inductor and a tank capacitor connected in series. Lossless sampling of the output voltage of the electronic ballast is achieved by monitoring the voltage across a sampling capacitor placed in series with the tank capacitor. A resistive and capacitive filter is used to filter the monitored voltage such that it can be accurately received by a microcontroller. A resistor is connected in series with the sampling capacitor to produce an open circuit output voltage control signal that is used by the microcontroller to limit the open circuit output voltage. A cable compensation circuit is utilized to minimize variations in the open circuit voltage due to the connecting and disconnecting of a cable to the ballast output terminals.

Electronic ballasts are used to provide power to gas discharge lamps such as fluorescent lights. These ballasts often sense the voltage applied to the lamp to monitor the functioning of the lamp and ballast. To sense the lamp voltage with a microcontroller, prior art ballasts such as set forth in U.S. Pat. No. 5,925,990, sample the lamp voltage through a resistor connected in series with a resonant capacitor. The voltage across the resistor represents the current in a resonant inductor, which is in turn proportional to the voltage across the resonant capacitor. However, in order to fully utilize the resolution of the A/D converter of the microcontroller, the voltage drop across the resistor needs to be relatively high. As a result, more than 2 watts of power are typically consumed at the output of the resonant inverter which increases the required input power to the ballast. Therefore, since efficiency is very important in modern lighting designs, an improved method and apparatus for sensing lamp voltage that consumes less power is needed.
In some prior art ballasts, the voltage on the lamp voltage sensing resistor is also used to control the open circuit voltage during striking when no lamp is connected. To accomplish this, the pulse width of one or both switches of the half bridge is typically controlled. Controlling the pulse width controls the open circuit voltage indirectly by using inductor current to control the voltage on the capacitor. As a result, large open circuit voltage variations often result when external connections to the fixture, such as cables, add extra capacitance. In ballast implementations that can afford to use a large resonant capacitor and a small inductor, the open circuit voltage variation problem is generally not significant. However, potentially damaging hard switching or capacitive mode switching is often observed with this type of prior art open circuit voltage controlled ballast. Furthermore, the use of a large resonant capacitor makes the resonant tank difficult to design. As a result, these types of ballasts suffer from more conduction losses and/or hard switching during the striking of the lamp than do typical ballasts. Conduction losses and hard switching are undesirable in that they may ultimately cause the ballast to fail. A large resonant capacitor, with a striking voltage of two lamps across it, stores a substantial amount of energy. When the striking attempt occurs when there is no load, the striking energy is transferred to the resonant inductor and can saturate the inductor. The result is undesirable hard switching occurring during the striking. Even though a MOSFET can survive the high stress transients in ballasts with a 460V bulk voltage, hard switching is undesirable and should be avoided if possible since it may result in damage. Furthermore, for some types of ballasts, it is critically important to avoid hard switching due to their particular susceptibility to damage from transients. Thus, in many of the prior art ballasts, the resonant capacitor value is minimized and a cable compensation circuit is utilized to control the open circuit voltage such that it is constant with various lengths of connecting cables having varying amounts of capacitance. However, these circuits are often complex and decrease the efficiency while increasing the cost of the ballast. Therefore, an improved method and apparatus for sensing and controlling the open circuit voltage of a ballast is needed.

This patent is subject to a terminal disclaimer.

Lossless circuit for sampling of lamp voltage


There is disclosed a receiver for receiving a multi-band DMT signal. The receiver includes a plurality of demodulators, each demodulator having a discrete Fourier transform and being provided to demodulate a respective one of a plurality of bands in the multi-band signal, the multi-band signal being modulated in an inverse discrete Fourier transform. A method of demodulating a multi-band signal is also provided.

Referring to FIG. 1 there is shown an example of a multi-band signal transmitted in the upstream (or uplink) of a communications system. In this example it is assumed that the multi-band signal comprises two bands. As shown in FIG. 1, a first band is defined between the frequencies f1 and f2, and a second band is defined between the frequencies f3 and f4. A downstream frequency band may be provided between the frequencies f2 and f3, and a further downstream frequency band may be provided beyond the frequency f4.
Techniques for transmitting and receiving such multi-band signals are well known. For example, in modern technology a multi-carrier signal having multiple frequency bands is transmitted.
At the receive side, such multi-band signals require a large amount of processing. The processing speed of the receiver is determined by the highest frequency of the multi-band signal. That is, the receiver has to operate at a speed such that the received signals having the highest frequencies can be processed within system constraints.
It is an object of the present invention to provide an improved multi-band DMT receiver in which an improved processing of the received signal is achieved.


An electrophotographic photoreceptor comprising a conductive substrate, a photoconductive layer formed on the substrate, and a surface layer formed on the photoconductive layer, wherein the surface layer comprises a polymer mainly composed of a siloxane bond and an imide bond. The photoreceptor has small dark decay and excellent mechanical strength and causes no image blurring under high humidity conditions and therefore can be used in a general electrophotographic process. When used in a laser printer using a coherent light source, the photoreceptor produces high quality images free from a Moire fringe.

Amorphous silicon (hydrogenated amorphous silicon) is a recently developed material for making a photosensitive layer of an electrophotographic photoreceptor, and various improvements have been attained. A photoreceptor using amorphous silicon is usually prepared by forming an amorphous silicon film on a conductive substrate by glow discharge decomposition of silane gas (SiH.sub.4). The thus formed amorphous silicon film contains a hydrogen atom and exhibits satisfactory photoconductivity. The amorphous silicon photoreceptor exhibits various advantages, such as excellent wear resistance due to the high surface hardness of the photosensitive layer, high heat resistance, electrical stability, broad spectral sensitivity, and high photosensitivity, which are ideal properties needed for an electrophotographic photoreceptor.
Notwithstanding these excellent properties, an amorphous silicon photoreceptor undergoes a large dark decay due to its relatively low dark resistance. This leads to a disadvantage in that a sufficient potential cannot be obtained on charging. That is, when a charged amorphous silicon photoreceptor is imagewise exposed to light to form an electrostatic latent image and then the latent image is developed, the surface potential of the photoreceptor decays by the time of the exposure, or the charges on the non-exposed area also decay by the time to the development, resulting in a failure of keep the potential necessary for development.
The potential decay is dependent on environmental conditions and becomes conspicuous particularly under high temperature and high humidity conditions. Besides, the initial surface potential attained gradually decreases on repeated use. Such an electrophotographic photoreceptor undergoing great dark decay only produces copies having a low image density and poor reproducibility of halftone.
In order to overcome this problem, it has been proposed to form a charge blocking layer (charge injection preventing layer) comprising amorphous silicon carbide, amorphous silicon nitride, amorphous silicon oxide, etc. by plasma CVD (chemical vapor deposition) on the amorphous silicon photoconductive layer. The charge blocking layer also serves as a surface protective layer.
However, an amorphous silicon photoreceptor having such a surface layer causes image smearing or blur on repeated use, particularly under high humidity conditions, and it cannot be used in an ordinary electrophotographic process.
JP-A-2-111962 (the term "JP-A" as used herein means an "unexamined published Japanese patent application") teaches formation of a surface protective and lubricating layer mainly composed of an organic binder resin, but the proposed surface layer is too thin (10 to 300 nm) for practical use.
Further, amorphous silicon formed by plasma CVD, though having high surface hardness, is less resistant against impact and is broken more easily than a selenium photoconductive layer or an organic photoreceptor. Therefore, a photoreceptor mainly composed of amorphous silicon is likely to suffer from scratches on contact with a paper stripping click, etc., and the scratches develop white spots or black spots on reproduced images.
Furthermore, an amorphous silicon photoreceptor generally has many hemispherical defects of 1 to 30 .mu.m in diameter on its surface. On repeated use, electrical or mechanical destruction occurs at the film defects causing white spots or black spots to develop on reproduced images.

Photoreceptor with polymer overlayer having siloxane and imide moieties


In the production of bisphenol-A from the reaction of phenol and acetone, values are recovered from a "heavy ends" fraction by passing the fraction through a thin-film evaporator, making a light fraction which is fractionally distilled into three portions, two of which have recoverable proportions of bisphenol-A, and recovering bisphenol-A from at least one of them.

The manufacture of 2,2-bis(4-hydroxyphenyl) propane, or "bisphenol-A" ("BPA") by the reaction of phenol and acetone is well known and practiced commercially. See U.S. Pat. No. 3,242,219 and French Patents 1,179,377, 1,342,760, and 1,353,609.
Commonly produced in such manufacture is a waste stream which may comprise at least 50%, and up to about 90% (by weight) BPA. Because of the difficulty heretofore of recovering the BPA from the waste stream, it is generally burned along with the waste or otherwise disposed of at minimal value. In an HCl-catalyzed process, this stream typically is 3-4% of total plant production. Such waste streams may be produced, for example, in the crystallization processes described in "Industrial Crystallization for Ultrapure Products" by Charles G. Moyers, Jr., CEP May 1986, pp 42-46, and in U.S. Pat. No. 4,209,646.
We are not aware of a process similar to ours which is designed to recover values from a BPA waste stream such as we obtain in our plant, i.e. having from 50-90% para-para BPA (p,p-BPA), 5-35% ortho-para BPA (o,p-BPA) and 0-15% phenol, along with 5 to 30% other, higher molecular weight materials including about 3 to about 15% (based on the whole composition) of a reaction product of phenol and mesityl oxide, 2,2,4-trimethyl-4-hydroxyphenyl-chroman, which will be referred to herein as "codimer" (see the structural formula I below). Such a waste stream may be assumed to be present in the bottoms of column 13, described in the aforementioned U.S. Pat. No. 4,209,646, which is incorporated herein by reference in its entirety.
Additional compounds, included in "other" above, are 2,4,4-trimethyl-2-hydroxyphenyl-chroman (II), the isopropenyl dimer (III), "bisphenol-X", or trisphenol (IV), a spiro compound (V), a compound which may be referred to as "4 ring A" (VI) and one referred to as "14 ring B" (VII). Chroman is a particularly troublesome impurity because its boiling point is slightly lower than p,p-BPA, but higher than o,p-BPA. U.S. Pat. No. 4,954,661 teaches some steps similar to the present invention, but it is more complex and does not address the important issue of codimer removal. ##STR1##

Recovering values from heavy ends in bisphenol-A production


A robotic case packing system loads articles from a moving conveying system into a container. The system has a pivot drive shaft pivotally connected to a support frame for selective rotation about a selected axis of rotation and has a drive linkage operatively connected between a servo motor and to the pivot drive shaft to selectively pivot the pivot drive shaft. A two-axis-robot is mounted on the pivot drive shaft along the axis of rotation such that movement of the two-axis-robot along its two axes of movement occurs within planes substantially parallel to the axis of rotation. A controller operatively connected to the servo motor is used to selectively actuate the servo motor to rotate the pivot drive shaft in order to enable selective picking and placing of articles with the robotic case packing system.

1. Field of the Invention
The present invention relates to case packing systems and, more particularly, it relates to a robotic case packing system for loading articles from a moving conveyor belt or similar moving conveyor system into a container such as a corrugated cardboard box.
2. Description of Related Art
For many years, attempts have been made to develop improved systems for picking up individual articles of product from a conveyor belt or similar moving conveyor system and depositing those articles within a container such as a corrugated cardboard box. The issues presented include how to accomplish this task, with both the desired speed and the desired accuracy. To meet the demand for speed, past solutions have included incorporation of multiple robots along the conveyor. For example, see the device described in applicant's U.S. Pat. No. 6,540,063, which patent is fully incorporated herein by reference. Often, if four such robot heads were used, each head would pick up every fourth article of product in a conveying system in a staggered manner such that the four robot heads effectively removed four consecutive articles of product during each iteration. While this multiplicity of heads did provide for a multiplying of speed, the means for moving the robot heads from the conveying belt and to the container were often awkward or cumbersome in implementation. Similarly, such systems were sometimes limited to loading cases only in multiples of the number of heads within the system. For example, if four heads were used, a case could be loaded with four, eight, or twelve articles; but it could not be loaded with seven or fifteen articles without complex programming or a drop in efficiency.
To provide greater flexibility, multi-axis robots have been developed for picking an article off of a common belt. Many such multi-axis robots, however, have proven to be fairly slow and heavy. Hence, while such robots may provide greater flexibility in motion, they have also provided a need for an even greater number of robots to meet the speed requirements in the marketplace today. Additionally, it has been found that with some three-axis robots, the range of movement may be limited in certain directions. For example, certain three-axis robots are very limited in their vertical component, which can make movement of a bag from a conveying belt into a deep container difficult.
Moreover, while two-axis robots provide a desired range of horizontal and vertical motion in a single plane, such robots do not generally accommodate three dimensional movement of an article from a conveyor belt over and down into a container unless the third element of motion is otherwise provided. To address this problem, attempts have been made to move a two-axis robot back and forth on linear slides to thereby introduce the third element of motion. This approach, however, appears to limit operating speed and increase the cost of the structure.
It is therefore desirable to provide an improved system that has the desired speed of operation with the desired range of movement, and that accurately picks articles of product from a conveying system and places them into a container.


A semiconductor device includes a Si substrate, a gate insulating film formed on the Si substrate, the gate insulating film being formed of an oxide film containing at least one selected from the group of Zr, Hf, Ti and a lanthanoid series metal, and having a single local minimal value on a high binding energy side of an inflection point in first differentiation of an O1s photoelectron spectrum, and a gate electrode formed on the gate insulating film.

1. Field of the Invention
The present invention relates to a semiconductor device and a manufacturing method thereof, and more particularly relates to a semiconductor device having a high-dielectric-constant gate insulating film and to a manufacturing method thereof.
2. Description of the Related Art
Development of Si-LSI has been achieved by a size reduction of elements in accordance with a scaling law. According to this scaling law, a gate insulating film in a next-generation MOS-type field effect transistor having a gate length less than 0.1 μm is required to have a film thickness of 1.5 nm or less in terms of an equivalent thickness of SiO2.
In a case of SiO2, leakage current due to direct tunnel current cannot be restrained in an area of this film thickness, and this increases power consumption, so that SiO2 cannot be applied as the gate insulating film any longer in a next generation. Thus, to provide an alternative material, research and development have been intensively conducted for a high-dielectric-constant insulating film, that is, a high-k film which has a high dielectric constant and an increased film thickness so that the leakage current can be restrained, and many high-k materials have been proposed so far (e.g., refer to IEDM Tech. Dig. (2003) 107.).
However, in most of the high-k films heretofore proposed, the high-k film reacts with a Si substrate to generate a low-dielectric-constant interfacial layer at an interface therebetween. The generation of the undesired low-dielectric-constant interfacial layer is caused by a heat treatment during or after film formation. The generation of the low-dielectric-constant interfacial layer then results in a decrease in the dielectric constant as the gate insulating film, which is a primary factor preventing utilization of the high-dielectric-constant characteristics intrinsic to the high-k material.
There has thus been a demand to achieve a semiconductor device and a manufacturing method thereof which prevent the generation of the low-dielectric-constant interfacial layer during the film formation, can also restrain the generation of the low-dielectric-constant interfacial layer after the heat treatment and effectively use the high-k film as the gate insulating film.

Semiconductor device and manufacturing method thereof


An ion implantation device for vaporizing decaborane and other heat-sensitive materials via a novel vaporizer and vapor delivery system and delivering a controlled, low-pressure drop flow of vapors, e.g. decaborane, into the ion source. The ion implantation device includes an ion source which can operate without an arc plasma, which can improve the emittance properties and the purity of the beam and without a strong applied magnetic field, which can improve the emittance properties of the beam. The ion source is configured so that it can be retrofit into the ion source design space of an existing Bernas source-based ion implanters and the like or otherwise enabling compatibility with other ion source designs.

1. Field of Invention
The invention provides production-worthy ion sources and methods capable of using new source materials, in particular, heat-sensitive materials such as decaborane (B10H14), and hydrides and dimer-containing compounds novel to the ion implantation process, to achieve new ranges of performance in the commercial ion implantation of semiconductor wafers. The invention enables shallower, smaller and higher densities of semiconductor devices to be manufactured, particularly in Complementary Metal-Oxide Semiconductor (CMOS) manufacturing. In addition to enabling greatly enhanced operation of new ion implanter equipment in the manufacture of semiconductor devices, the invention enables the new ion source to be retrofit into the existing fleet of ion implanters with great capital cost savings. Embodiments of the invention uniquely implant decaborane and the other dopant materials in particularly pure ion beams, enabling a wide range of the needs of a fabrication facility to be met. Various novel constructional, operational and process features that contribute to the cost-effectiveness of the new technology are applicable as well to prior technology of the industry.
2. Description of the Prior Art
As is well known, ion implantation is a key technology in the manufacture of integrated circuits (ICs). In the manufacture of logic and memory ICs, ions are implanted into silicon or GaAs wafers to form transistor junctions, and to dope the well regions of the p-n junctions. By selectively controlling the energy of the ions, their implantation depth into the target wafer can be selectively controlled, allowing three-dimensional control of the dopant concentrations introduced by ion implantation. The dopant concentrations control the electrical properties of the transistors, and hence the performance of the ICs. A number of dopant feed materials have previously been used, including As, Ar, B, Be, C, Ga, Ge, In, N, P, Sb and Si. For those species which are of solid elemental form, many are obtainable in gaseous molecular form, such as fluoride compounds that are ionizable in large quantities at significantly elevated temperatures. The ion implanter is a manufacturing tool which ionizes the dopant-containing feed materials, extracts the dopant ions of interest, accelerates the dopant ions to the desired energy, filters away undesired ionic species, and then transports the dopant ions of interest to the wafer at the appropriate energy for impact upon the wafer. The presence in the implanter of certain elements, such as the disassociated element fluorine, is detrimental to the implanted wafers, but, despite such drawbacks, trace amounts of such contaminants have been tolerated in many contexts, in the interest of achieving production-worthy throughput volume. Lower contaminant levels from what is now achievable is desired.
In a complex relationship, overall, a number of variables must be controlled in order to achieve a desired implantation profile for a given ion implantation process:                The nature of the dopant feed material (e.g., BF3 gas)        Dopant ion species (e.g., B+)        Ion energy (e.g., 5 keV)        Chemical purity of the ion beam (e.g., <0.01% energetic contaminants)        Isotopic purity of the ion beam (e.g., ability to discriminate between 113In and 115In)        Energy purity of the ion beam (e.g., <2% full width at half maximum, i.e. FWHM)        Angular divergence and spatial extent of the beam on the wafer        Total dose (e.g., 1015 atoms/cm2) implanted on the wafer        Uniformity of the dose (e.g., ±1% variation in the implanted density over the total wafer surface area).
These variables affect the electrical performance, minimum manufacturable size and maximum manufacturable density of transistors and other devices fabricated through ion implantation.
A typical commercial ion implanter is shown in schematic in FIG. 1. The ion beam I is shown propagating from the ion source 42 through a transport (i.e. "analyzer") magnet 43, where it is separated along the dispersive (lateral) plane according to the mass-to-charge ratio of the ions. A portion of the beam is focused by the magnet 43 onto a mass resolving aperture 44. The aperture size (lateral dimension) determines which mass-to-charge ratio ion passes downstream, to ultimately impact the target wafer 55, which typically may be mounted on a spinning disk 45. The smaller the mass resolving aperture 44, the higher the resolving power R of the implanter, where R=M/ΔM (M being the nominal mass-to-charge ratio of the ion and ΔM being the range of mass-to-charge ratios passed by the aperture 44). The beam current passing aperture 44 can be monitored by a moveable Faraday detector 46, whereas a portion of the beam current reaching the wafer position can be monitored by a second Faraday detector 47 located behind the disk 45. The ion source 42 is biased to high voltage and receives gas distribution and power through feedthroughs 48. The source housing 49 is kept at high vacuum by source pump 50, while the downstream portion of the implanter is likewise kept at high vacuum by chamber pump 51. The ion source 42 is electrically isolated from the source housing 49 by dielectric bushing 52. The ion beam is extracted from the ion source 42 and accelerated by an extraction electrode 53. In the simplest case (where the source housing 49, implanter magnet 43, and disk 45 are maintained at ground potential), the final electrode of the extraction electrode 53 is at ground potential and the ion source is floated to a positive voltage Va, where the beam energy E=qVa and q is the electric charge per ion. In this case, the ion beam impacts the wafer 55 with ion energy E. In other implanters, as in serial implanters, the ion beam is scanned across a wafer by an electrostatic or electromagnetic scanner, with either a mechanical scan system to move the wafer or another such electrostatic or electromagnetic scanner being employed to accomplish scanning in the orthogonal direction.
A part of the system of great importance in the technology of ion implantation is the ion source. FIG. 2 shows diagrammatically the "standard" technology for commercial ion sources, namely the "Enhanced Bernas" arc discharge ion source. This type of source is commonly the basis for design of various ion implanters, including high current, high energy, and medium current ion implanters. The ion source a is mounted to the vacuum system of the ion implanter through a mounting flange b which also accommodates vacuum feedthroughs for cooling water, thermocouples, dopant gas feed, N2 cooling gas, and power. The dopant gas feed c feeds gas, such as the fluorides of a number of the desired dopant species, into the arc chamber d in which the gas is ionized. Also provided are dual vaporizer ovens e, f inside of the mounting flange in which solid feed materials such as As, Sb2O3, and P may be vaporized. The ovens, gas feed, and cooling lines are contained within a water cooled machined aluminum block g. The water cooling limits the temperature excursion of the aluminum block g while the vaporizers, which operate between 100 C and 800 C, are active, and also counteracts radiative heating by the arc chamber d when the ion source is active. The arc chamber d is mounted to, but designedly is in poor thermal contact with, the aluminum block g. The ion source a employs an arc discharge plasma, which means that it operates by sustaining within a defined chamber volume a generally narrow continuous electric arc discharge between hot filament cathode h, residing within the arc chamber d, and the internal walls of the arc chamber d. The arc produces a narrow hot plasma comprising a cloud of primary and secondary electrons interspersed with ions of the gas that is present. Since this arc can typically dissipate in excess of 300 W energy, and since the arc chamber d cools only through radiation, the arc chamber in such Bernas ion sources can reach a temperature of 800 C during operation.
The gas is introduced to arc chamber d through a low conductance passage and is ionized through electron impact with the electrons discharged between the cathode h and the arc chamber d and, as well, by the many secondary electrons produced by the arc discharge. To increase ionization efficiency, a substantial, uniform magnetic field i is established along the axis joining the cathode h and an anticathode j by externally located magnet coils, 54 as shown in FIG. 1. This provides confinement of the arc electrons, and extends the length of their paths. The anticathode j (sometimes referred to as a "repeller") located within the arc chamber d but at the end opposite the cathode h is typically held at the same electric potential as the cathode h, and serves to reflect the arc electrons confined by the magnetic field i back toward the cathode h, from which they are repelled back again, the electrons traveling repeatedly in helical paths. The trajectory of the thus-confined electrons results in a cylindrical plasma column between the cathode h and anticathode j. The arc plasma density within the plasma column is typically high, on the order of 1012 per cubic centimeter; this enables further ionizations of the neutral and ionized components within the plasma column by charge-exchange interactions, and also allows for the production of a high current density of extracted ions. The ion source a is held at a potential above ground (i.e., above the potential of the wafer 55) equal to the accelerating voltage Va of the ion implanter: the energy, E, of the ions as they impact the wafer substrate is given by E=qVa, where q is the electric charge per ion.
The cathode h of such a conventional Bernas arc discharge ion source is typically a hot filament or an indirectly-heated cathode which thermionically emits electrons when heated by an external power supply. It and the anticathode are typically held at a voltage Vc between 60V and 150V below the potential of the ion source body Va. Once an arc discharge plasma is initiated, the plasma develops a sheath adjacent the exposed surface of the cathode h within chamber d. This sheath provides a high electric field to efficiently extract the thermionic electron current for the arc; high discharge currents (e.g., up to 7 A) can be obtained by this method.
The discharge power P dissipated in the arc chamber is P=D Vc, typically hundreds of watts. In addition to the heat dissipated by the arc, the hot cathode h also transfers power to the walls of the arc chamber d. Thus, the arc chamber d provides a high temperature environment for the dopant arc plasma, which boosts ionization efficiency relative to a cold environment by increasing the gas pressure within the arc chamber d, and by preventing substantial condensation of dopant material on the hot chamber walls.
If the solid source vaporizer ovens e or f of the Bernas arc discharge ion source are used, the vaporized material feeds into the arc chamber d with substantial pressure drop through narrow vaporizer feeds k and l, and into plenums m and n. The plenums serve to diffuse the vaporized material into the arc chamber d, and are at about the same temperature as the arc chamber d. Radiative thermal loading of the vaporizers by the arc chamber also typically prevents the vaporizers from providing a stable temperature environment for the solid feed materials contained therein below about 200 C. Thus, typically, only solid dopant feed materials that both vaporize at temperatures >200 C and decompose at temperatures >800 C (the temperature of the walls of the ionization chamber of a typical Bernas source) can be successfully vaporized and introduced by this method.
A very significant problem which currently exists in the ion implantation of semiconductors is the limitation of production-worthy ion implantation implanters that prevents effective implanting of dopant species at low (e.g., sub-keV) energies at commercially desired rates. One critically important application which utilizes low-energy dopant beams is the formation of shallow transistor junctions in CMOS manufacturing. As transistors shrink in size to accommodate more transistors per IC according to a vital trend, the transistors must be formed closer to the surface of the target wafer. This requires reducing the velocity, and hence the energy, of the implanted ions, so that they deposit at the desired shallow level. The most critical need in this regard is the implantation of low-energy boron, a p-type dopant, into silicon wafers. Since boron atoms have low mass, at a given energy for which the implanter is designed to operate, they must have higher velocity and will penetrate deeper into the target wafer than other p-type dopants; therefore there is a need for boron to be implanted at lower energies than other species.
Ion implanters are relatively inefficient at transporting low-energy ion beams due to space charge within the ion beam, the lower the energy, the greater the problem. The space charge in low energy beams causes the beam cross-section area (i.e. its "profile") to grow larger as the ions proceed along the beam line (there is "beam blow-up"). When the beam profile exceeds the profile for which the implanter's transport optics have been designed, beam loss through vignetting occurs. For example, at 500 eV transport energy, many ion implanters currently in use cannot transport enough boron beam current to be commercially efficient in manufacturing; i.e., the wafer throughput is too low because of low implantation dose rate. In addition, known ion sources rely on the application of a strong magnetic field in the source region. Since this magnetic field also exists to some extent in the beam extraction region of the implanter, it tends to deflect such a low-energy beam and substantially degrade the emittance properties of the beam, which further can reduce beam transmission through the implanter.
An approach has been proposed to solve the problem of low-energy boron implantation: molecular beam ion implantation. Instead of implanting an ion current I of atomic B+ ions at an energy E, a decaborane molecular ion, B10Hx+, is implanted at an energy 10×E and an ion current of 0.10×I. The resulting implantation depth and dopant concentration (dose) of the two methods have been shown to be generally equivalent, with the decaborane implantation technique, however, having significant potential advantages. Since the transport energy of the decaborane ion is ten times that of the dose-equivalent boron ion, and the ion current is one-tenth that of the boron current, the space charge forces responsible for beam blowup and the resulting beam loss can potentially be much reduced relative to monatomic boron implantation.
While BF3 gas can be used by conventional ion sources to generate B+ ions, decaborane (B10H14) must be used to generate the decaborane ion B10Hx+. Decaborane is a solid material which has a significant vapor pressure, on the order of 1 Torr at 20 C, melts at 100 C, and decomposes at 350 C. To be vaporized through preferred sublimination, it must therefore be vaporized below 100 C, and it must operate in a production-worthy ion source whose local environment (walls of the ionization chamber and components contained within the chamber) is below 350 C to avoid decomposition. In addition, since the B10H14 molecule is so large, it can easily disassociate (fragment) into smaller components, such as elemental boron or diborane (B2H6), when subject to charge-exchange interactions within an arc discharge plasma, hence it is recognized that conventionally operated Bernas arc plasma sources can not be employed in commercial production, and that ionization should be obtained primarily by impact of primary electrons. Also, the vaporizers of current ion sources cannot operate reliably at the low temperatures required for decaborane, due to radiative heating from the hot ion source to the vaporizer that causes thermal instability of the molecules. The vaporizer feed lines k, l can easily become clogged with boron deposits from decomposed vapor as the decaborane vapor interacts with their hot surfaces. Hence, the present production-worthy implanter ion sources are incompatible with decaborane ion implantation. Prior efforts to provide a specialized decaborane ion source have not met the many requirements of production-worthy usage.
More broadly, there are numerous ways in which technology that has been common to the industry has had room for improvement. Cost-effective features, presented here as useful in implementing the new technology, are applicable to implementation of the established technology as well.

Ion implantation ion source, system and method


A game engine sensor of a computing device executing an operating system receives first data from the operating system that represents occurrence of a monitored event. The game engine sensor sends second data corresponding to the monitored event to a game engine logic controller. A first logic block of the game engine logic controller determines, based on the second data and third data representing a system state of the computing device, that a first predicate condition is satisfied. A second logic block of the game engine logic controller determines, based on the second data and the third data, that a second predicate condition is satisfied. A computer security threat is detected based on the first and second predicate conditions being satisfied, and at least one game engine actuator is instructed to perform at least one action responsive to the computer security threat.

As computer systems and devices have become more popular, such systems and devices have become targets for malicious activity, such as viruses, malware, ransomware, phishing attacks, etc. Various computer security solutions are available to users and enterprises to try and prevent such malicious activity. Some computer security solutions are signature-based, and compare potentially malicious files or payloads to a signature that is known to correspond to malicious file(s). However, these solutions are only as good as the underlying signatures, and trying to issue signature updates to keep up with everchanging threats is a losing proposition, especially because sophisticated malware often has the ability to automatically mutate and defeat signature-based detection. Artificial intelligence (AI)-based solutions input a potentially malicious file (or data derived therefrom) into an AI model (e.g., a neural network) to predict whether or not the file is malicious. However, the effectiveness of an AI-based solution is determined by the underlying model, and it may sometimes be difficult to obtain sufficiently complete training data to train the model.


A method for decoding video data blocks using variable length codes, comprising transforming information about the spatial frequency distribution of a video data block into pixel values. Prior to said transformation, a first reference value (Xref) representing the abruptness of variations in information about spatial frequency distribution within the block is generated, after said transformation, a second reference value (Δ) representing the abruptness of variation in certain information between the block and at least one previously transformed video data block is generated. The first reference value (Xref) is compared to a first threshold value (TH1) and the second reference value (Δ) to a second threshold value (TH2); and as a response to either of the first (Xref) and second reference values (Δ) being greater than the first (TH1) and respectively the second threshold value (TH2), an error in the block is detected.

One of the targets in telecommunications is to provide systems where good quality, real-time transmission of video, audio and data services is available. As is generally known, the amount of data needed to transfer moving pictures is high compared to many other types of media, and so far, usage of video in low bit-rate terminals has been negligible. Transmission of data in digital form, anyhow, has provided for increased signal-to-noise ratios and increased information capacity in the transmission channel. In the near future advanced digital mobile telecommunication systems will also be introducing services enhancing the transmission bit-rates, which means that transmission of video even over low bit-rate mobile channels will soon become more feasible.
For optimisation of channel capacity usage, signals are generally compressed before transmission. This is especially important with video transmission, where the amount of data to be transmitted is large. Compressed video, is easily afflicted by transmission errors, mainly because the information content of compressed video is generally coded using variable length codes. When a bit error alters the codeword to another one of different length, the decoder loses synchronisation and decodes consecutive error free blocks incorrectly until the next synchronisation code is received.
To limit the degradations in images caused by transmission errors, error detection and/or error correction methods can be applied, retransmissions can be used, and/or effects from the received corrupted data can be concealed. Normally retransmissions provide a reasonable way to protect data streams from errors, but long round-trip delays associated with low bit-rate transmission and moderate or high error rates make it practically impossible to use retransmission, especially with real-time videophone applications. Error detection and correction methods usually require a large overhead since they add some redundancy to the data. Consequently, for low bit-rate applications, error concealment can be considered as a good way to protect and recover images from transmission errors.
To be able to conceal transmission errors, they have to be detected and localised. The more is known about the type and location of the error, the better the concealment method can be focused to the problem, and accordingly the better image quality will be achieved. It is also important to find methods that can detect especially those errors that are easily detected by the human eye.
Lately, much interest has been attached to error-resilient digital video transmission, but the work has mainly been concentrated on digital TV transmission using MPEG-2. There the problem is solved mainly by adding unique sync codes frequently to the bit stream, using short packets with a cyclic redundancy check (CRC), and discarding all packets where the CRC indicates an error. When the bit-rate of transmission is a few megabytes per second, the proportion of frequently occurring sync codes or CRC fields in the whole data stream is usually acceptable. However, in low bit-rate transmission the situation is quite different, and with bit-rates of 20-30 kbps the optimisation of overheads is extremely important. Furthermore, if the size of the picture is for example 704*576 pixels, one 16*16 pixel macroblock covers about 0.061% of the whole picture, whereas in low bit-rate OCIF (Quarter Common Intermediate Format) 176*144 pixel pictures, one macroblock covers more than 1% of the whole image. Hence, the loss of a macroblock is more detrimental in low bit-rate videophone pictures than in television pictures.
The main interest in low bit-rate video coding standardisation bodies has been to improve error resilience of inter coded frames. Most presented methods suggest changing of the bit-stream syntax and coding algorithms, whereby they can be properly utilised only if they are widely supported by users' videophone terminals. Generally two methods of error detection have been put forward: detection of illegal variable length coding (VLC) code words, and detection of missing end block codes of discrete cosine transform (DCT) matrices. In practice these methods have been found to be insufficient especially for intra coded blocks, since a great many VLC errors remain undetected, and errors in fixed length coded DC components of intra coded blocks are often not detected at all. Furthermore, errors are usually detected far too late, after decoding several corrupted blocks.
The publication of Wai-Man Lam and Amy R. Reibman, "An error Concealment Algorithm for Images Subject to Channel Errors", in IEEE Transactions on Image processing, Vol. 4, No. 5, pp. 533-542, May 1995 presents some DCT and pixel domain error detection algorithms. These algorithms, however, do not apply adequately to low bit-rates and low resolutions, especially due to the inapplicability of DCT domain algorithms for the different characteristics of quantised DCT matrices.
The publication of Aki Hietala, "Virhesietoinen videodekoodaus", Master of Science Thesis, Oulu University, Department of Electrical Techniques, 1997, presents and analyses some methods for error detection in video bitstreams. The methods utilise the residual correlation of adjacent pixels (spatial correlation) and by detecting anomalies in block boundaries, search for corrupted blocks. However, the methods are considered rather complex and the achieved effect has not yet been sufficient.
The publication of M. R. Pickering, M. R. Frater, J. F. Arnold, and M. W. Grigg, "An Error Concealment Technique in the Spatial Frequency Domain", Signal Processing, no.54, Elsevier 1996, pp. 185-189 presents a method for concealing errors that are caused by blocks in the image which are similar in appearance to a single DCT basis function. In the method unusually large DCT coefficients in the 8*8 block of coefficients are detected and reduced to zero. This method works well with specific types of transmission errors, but as a single means of detection has a limited effect.

Error detection in low bit-rate video transmission


A method and apparatus for forming flanges on a panel. The flanges may be weld flanges or hem flanges. The flanges stretch to reduce spring back and may be trimmed. The trimming operation is performed after the flange area is formed on the panel.

1. Technical Field
This disclosure relates to sheet metal forming tools and processes that are used to form and trim a hem flange or weld flange.
2. Background Art
Vehicle body panels such as deck lids, hoods, doors and the like frequently include a flange that extends about their periphery. Such body panels have traditionally been manufactured from mild steel sheet metal. Mild steel is very ductile and is easily formed in a hem forming operation. Increasingly, automotive manufacturers are turning to aluminum or advanced high strength steel (AHSS) alloys to obtain weight savings for vehicle body panels. Aluminum alloys and AHSS alloys offer high strength/low weight alternatives to mild steel.
Aluminum and AHSS alloys do not, however, have the same degree of ductility and resistance to work hardening offered by mild steel. Forming a flange on a sheet metal body panel made of aluminum or AHSS alloys is more difficult than forming the same flange on a mild steel panel due to the reduced ductility of aluminum or AHSS alloys. One proposed solution to this problem is to form a larger radius hem when making body panels of aluminum sheet metal. Larger radius hems result in lower fit and finish ratings because larger radius hems may cause gaps to appear larger between door closure panels and their openings.
The low ductility of aluminum may cause tears or splits starting from the outer surface of a hem. Tears and splits result in high part rejection rates and unacceptable scrap rates.
Substantial work hardening may occur during the hem flange formation process. The hem flange formation process is the initial step in forming a hem wherein a peripheral portion of a blank or drawn part is bent to about 90 degrees. Forming a 90 degree bend in an aluminum sheet around a relatively tight radius causes substantial amounts of deformation. Stretching the trimmed surface may lead to edge cracking. This amount of strain may result in splits and even tears as the hem flange is further formed in pre-hem and final hem forming steps.
Flanging and hemming of aluminum panels often requires larger radii due to insufficient formability of aluminum alloys (6111-T4; 6022-T4; 6016-T4), advanced high strength steel (AHSS) (DP500 steel) and similar materials for outer skin panels. One of the major problems for implementation of AHSS and aluminum alloys for outer skin panels is splitting of the sheet material from the trimmed surface in stretch flanging and stretch hemming areas. Attempts to reduce the radius of a hem or flange have resulted in splits along the flanging line. Applicants have proposed a two-step flanging operation in which a large radius bend is first made and then a smaller radius bend is made on the larger radius bend. A cam former that requires a complex tooling arrangement may be used to form a smaller radius bend after a larger radius bend is made in a normal flange forming die.
A simpler tooling configuration would be preferable that could obtain sharp flanging in a single step. A tooling solution would be preferred that would facilitate combining and simplifying the steps of drawing, trimming and flanging. There is a need for a flange forming and trimming tool that can form a sharper peripheral radii on a flange in one step without employing an expensive cam mechanism and without requiring an extra stamping operation.
Flange splitting from the sheared surface is a barrier to implementation of higher strength lower guage AHSS steels, such as DP500, for outer skin panels in auto industry. It is also a reason for the limited implementation of aluminum on vehicles. The use of aluminum in vehicle body parts has frequently been limited to hoods, with substantial difficulties being encountered when it is attempted to use aluminum for fenders and decklids.
In conventional sheet metal forming operations a flange is first trimmed and then flanged. Tooling dies may become contaminated with slivers that are formed when a flange splits. Slivers can be spread to the subsequent operations from the trimming operation because it is usually not a final part forming operation. Elimination of slivers is important for outer skin panels that must have a high quality class A surface.
Another problem is that aluminum or AHSS alloy panels tend to spring-back elastically after cold forming. Spring-back can be accommodated and remedied by re-striking the panel to eliminate stresses in the metal that cause spring-back.
These and other problems are addressed by Applicant's disclosure as summarized below.

Method and apparatus for sharp flanging and trimming sheet metal panels


A liquid jet recording method includes applying thermal energy to liquid in a liquid passage to produce film boiling of the liquid to produce a. bubble; permitting the bubble to communicate with ambience; wherein the liquid passage is not blocked in the communicating step.

The present invention relates to a recording method and a recording apparatus having a process step by which a bubble produced by thermal energy communicates with ambience, more particularly to a recording method and apparatus such as a printer for recording images or characters on paper or cloth (recording material) in accordance with a recording signal, a copying machine, a facsimile machine having an information transmitting system, an electronic typewriter having a keyboard, a wordprocessor, or a compound system or the like.
Among various recording methods which have been put into practice for various printers, an ink jet system as disclosed in U.S. Pat. Nos. 4,723,129, 4,740,796 or the like, which uses thermal energy to produce film boiling, is advantageous. In one of the types a liquid passage is not blocked by the bubble in U.S. Pat. No. 4,410,899.
The prior art is applicable to various recording systems, but they do not disclose or teach, to the practical level, the system wherein the created bubble communicates with the ambience. This system will be called xe2x80x9cambience communication systemxe2x80x9d.
As one type of the ambience communication system, there is a system in which the bubble explodes. However, since the liquid ejection is not stabilized, it is not practical. Japanese Laid-Open Patent Application No. 161935/1979 discloses a cylindrical nozzle provided with an internal cylindrical heater in which the nozzle is blocked by the bubble, although the ejection principle is not known, but it splashes a great number of fine ink droplets as well as the relatively large major droplet.
Japanese Laid-Open Patent Application No. 185455/1986 discloses that liquid ink is filled in a small clearance between a heat generating head and a plate member having small openings and is heated by the heat generating head to create a bubble to eject a droplet of the ink through the fine opening. Also, the gas forming the bubble is ejected through the fine opening. By doing so, an image is formed on a recording material.
Japanese Laid-Open Patent Application No. 20 249768/1986 discloses that a bubble is formed by application of thermal energy to liquid ink. By the expansion force of the bubble, a small droplet of the ink is formed and ejected. Simultaneously, the gas forming the bubble is ejected through a large opening into the atmosphere. By doing so, an image is formed on the recording material. The system of this publication is characterized by the absence of the wall.
These two publications at most, disclose the ambience communication system by simply stating so or by simply expressing in the drawing. The details of the bubble are not considered.
Japanese Laid-Open Patent Application No. 197246/1986 discloses recording apparatus using thermal energy, in which the ink is supplied into plural bores and is heated by a recording head having heat generating means to the temperature of 150-200xc2x0 C., by which a droplet of the ink is ejected onto the recording material. However, in the recording apparatus of this type, it is difficult to completely closely dispose the heat generating element and the recording medium, and therefore, the thermal efficiency is not as good as expected, and therefore, it is not suitable for a high speed recording, as the case may be. This publication discloses ejection of the ink using the pressure of the created bubble, but it does not disclose the specific principles of ejection. Therefore, any solution to the problem is not even suggested. This publication shows in its FIG. 3 the growth of the bubble, in which the bubble growth from a point, and therefore, it is understood that the bubble is created by an extension of the nucleate boiling. In addition, the communication between the bubble and the air occurs in a space away from the ejection outlet, and therefore, the ejection behavior is not stabilized in addition, the ink remains around the ejection outlet.
The present invention is intended to provide a practical solution to the problems with the ambience communication system ink jet recording apparatus. The present invention is based on new investigations and analysis as to the preferable conditions under which the bubble communicates with the ambience.
Accordingly, it is a principal object of the present invention to provide a recording method and apparatus wherein the splashing of the liquid due to the explosion of the bubble is suppressed.
It is another object of the present invention to provide a recording method and apparatus wherein the liquid droplet formation is stabilized.
It is a further object of the present invention to provide a recording method and a recording apparatus wherein the bubble communicates with the ambience under preferable conditions.
It is a further object of the present invention to provide a recording method and apparatus wherein the bubble communicates with the ambience under such a condition that the volume and the speed of the ejected droplet are stabilized.
It is a further object of the present invention to provide an on-demand recording method and a on-demand type recording apparatus wherein plural ejection outlets are arranged at a high density without the problem of undesirable temperature rise.
It is a further object of the present invention to provide an on-demand recording method and an on-demand recording apparatus which is excellent in the image quality and in the high frequency response.
It is a further object of the present invention to provide a recording method and a recording apparatus having a long service life.
It is a further object of the present invention to provide a recording method and a recording apparatus which is stable in the recording operation.
It is a further object of the present invention to provide a recording method and a recording apparatus which have plural liquid passages with good refilling property.
According to an aspect of the present invention, there is provided a liquid jet recording method, comprising: applying thermal energy to liquid in a liquid passage to produce film boiling of the liquid to produce a bubble; permitting the bubble to communicate with ambience; wherein the liquid passage is not blocked in the communicating step.
According to another aspect of the present invention, there is provided a liquid jet recording method wherein ink is heated to create a bubble which is effective to eject at least a part of the ink, the improvement resides in that the bubble communicates with ambience under the condition that an internal pressure of the bubble is lower than a pressure of the ambience.
According to a further aspect of the present invention, there is provided a recording method using a recording head including an ejection outlet for ejecting ink, a liquid passage communicating with the ejection outlet and an ejection energy generating means for generating thermal energy contributable to ejection of the ink by creation of a bubble in the liquid passage, wherein the bubble communicates with the ambience when la/lbxe2x89xa71 is satisfied, where la is a distance between an ejection outlet side end of the ejection energy generating means and an ejection outlet side end of the bubble, and lb is a distance between that end of the ejection energy generating means which is remote from the ejection outlet and that end of the bubble which is remote from the ejection outlet.
According to a yet further aspect of the present invention, there is provided a liquid jet method using a recording head having an ejection outlet for ejecting ink, a liquid passage communicating with the ejection outlet and an ejection energy generating element for generating thermal energy contributable to the ejection of the ink by creation of a bubble in the liquid passage, wherein a first order differential of a movement speed of an ejection outlet side end of the created bubble is negative, when the bubble created by the ejection energy generating means communicates with the ambience through the ejection outlet.
These and other objects, features and advantages of the present invention will become more apparent upon a consideration of the following description of the preferred embodiments of the invention taken in conjunction with the accompanying drawings.

Recording method and apparatus for controlling ejection bubble formation


The present invention relates to the field of video processing. Disclosed are a multi-processor video processing system and video image synchronous transmission and display method therein. Via PCIE bus technology, synchronous transmission and tiled display of video image in the multi-CPU system is implemented. In the present invention, the multi-processor system includes multiple processors that are connected via a PCIE bus and each comprises a display unit and a decoding unit; a memory area of the display unit comprises two buffers, a read information packet containing a read flag, and a write information packet containing a write flag. The method includes the following steps: a decoding unit generating a frame of uncompressed image, performing the following steps on each corresponding display unit: if the read and write flags corresponding to the display unit are equal, sending, by calling the PCIE bus or using local transmission, the image to an idle buffer indicated by the write flag, and negating the write flag; each display unit querying for corresponding read and write flags according to a display refresh frequency; if the read and write flags are not equal, using the buffer indicated by the read flag as a storage area for data to be displayed next time, and setting the read flag to a write flag value.

In the multi-CPU video processing system, real-time transmission of uncompressed video data is often the key link leading to the system performance bottleneck. A "general CPU and specialized processing chip" system structure is usually utilized for application focusing on data transmission, such as video stitching control, wherein the specialized processing chip concentrates on handling data receiving and processing to ensure real time of the processing.
In the prior art, a Chinese patent application with publication number CN 101986258 A has disclosed a technical solution of "general CPU and specialized processing chip" system structure for video stitching. However, the inventors of the present invention have found that said invention patent cannot be implemented in the peer star structure of peer multi-CPU system, though it can be implemented in such system structure as "general CPU plus specialized processing chip".
Therefore, a video processing technology for the peer structure of a multi-CPU system is desired.

Multi-processor video processing system and video image synchronous transmission and display method therein

Hangzhou Hikvision Digital Technology Co., Ltd.


A portable information processing device, including a main body comprising a projector configured to project an image; a state detection unit configured to detect a state of the main body; and an output control unit configured to control an output of the projector based on the state of the main body detected by the state detection unit.

Field of the Invention
The present invention relates to a portable information processing device, an output control method for a projector, and a recording medium.
Description of the Related Art
As the types of projector configured to project an image onto a projection surface such as a screen, there has been known a projector that is small in size and portable, in addition to a projector to be fixed to a ceiling or wall for use and a projector to be placed on a desk in a stationary manner. Some of the small and portable projectors are built into portable information processing devices, as in the case of a mobile phone having a projector function. Although the small and portable projector can be used with ease, the projection direction of this type of projector may be deviated easily toward a direction that is not intended by a user (such as a direction in which a person exists).
As a technology for preventing the projection direction from facing in the direction that is not intended by the user, there has been known a portable electronic device having a projector function disclosed in Japanese Patent Application Laid-Open No. 2009-3281. When this portable electronic device moves a distance more than a predetermined value, the portable electronic device measures the distance to the projection surface. When the measured distance is more than a predetermined distance, the portable electronic device stops or reduces the output of the projector.

Portable information processing device, output control method for a projector, and recording medium


An optical information recording medium has a substrate, and an optical reflection layer, an optical recording layer containing an organic dye, an interlayer, and a cover layer formed in this order on the substrate. The interlayer contains a sputtered Nb2O5—Al2O3-based composite oxide having an Nb2O5 content of more than 50 mol % and less than 60 mol %.

1. Field of the Invention
The present invention relates to an optical information recording medium, particularly to a high-recording-density optical information recording medium such as a Blu-ray disc having an optical recording layer containing an organic dye.
2. Description of the Related Art
Optical information recording media including optical disks have been widely used for information recording. For example, an optical information recording medium such as CD-R has a recording layer and a reflective layer formed in this order on an optically transparent resin substrate with a thickness of 1.2 mm and a diameter of 120 mm or 80 mm. In these years, there has been a demand for an optical information recording medium having a higher information recording density. Thus, use of a shorter laser wavelength (referred to as wavelength shortening) and use of an object lens having a higher numerical aperture (NA) (referred to as NA increasing) have been studied, and DVD±R and the like have been realized as such media. The DVD±R has two bonded 0.6-mm-thick optically transparent resin substrates, and has a reflective layer and a recording layer sandwiched between the substrates, so that the permissive tilt angle (tilt) value of the disc is increased by the wavelength shortening and the NA increasing.
Recently there has been a demand for a further higher information recording density in view of recording a high-definition viewdata. Thus, an optical information recording medium having a 1.1-mm-thick resin substrate, a reflective layer and a recording layer formed on the substrate, and a 0.1-mm-thick optically transparent cover layer formed on the reflective and recording layers has been proposed. Examples of the medium include a write-once type of Blu-ray Disc (registered trademark, hereinafter referred to as BD), BD-R (BD-Rewritable). Specifically, the medium has a disc-shaped substrate having an outer diameter of 120 mm, an inner diameter of 15 mm, and a thickness of approximately 1.1 mm, and further has an optical reflection layer, a phase change recording layer, and a cover layer having a thickness of approximately 0.1 mm on the substrate. The medium is capable of recording user information on the recording layer by irradiating the cover layer side with a laser light having a wavelength of approximately 405 nm from an optical head having a numerical aperture of approximately 0.85.
Though the recording layer of the above optical information recording medium is a phase change type layer, also a dye-containing type recording layer has been studied.
However, the dye-containing recording layer is disadvantageous in that, for example, when a transparent resin material is applied to the recording layer to form the cover layer, the coating liquid penetrates into the dye-containing recording layer.
In contrast, as shown in FIG. 5, in an optical recording medium proposed in JP-A-2003-36562, a reflective layer 2, a dye-containing recording layer 3, and a cover layer 5 are disposed on a substrate 1 to achieve recording/playback on the cover layer 5 side, and a barrier layer 4 for preventing mixing of the recording layer 3 and the cover layer 5 is formed between the recording layer 3 and the cover layer 5. The barrier layer 4 may contain at least one selected from silicon oxide, zinc sulfide, zinc oxide, silicon nitride, silicon carbide, cerium oxide, yttrium oxide, yttrium sulfide, and mixtures of an oxide and sulfur.
However, as described in JP-A-2003-36562, the optical recording medium is disadvantageous in that when the barrier layer 4 contains a sulfur-containing material, the sulfur is reacted with a metal (such as Ag) in the reflective layer 2, so that a sulfide is generated to deteriorate the preserving property.
Meanwhile, in an optical recording medium proposed in JP-A-2006-147135, at least a cover layer and a recording layer containing an organic dye are disposed on a substrate, and an interlayer with a thickness of 1 to 80 nm, composed of a Ta compound, an Nb compound, or a composite oxide containing Ta and/or Nb, is disposed between the recording layer and the cover layer. The interlayer may be formed by an RF sputtering method or a DC sputtering method.
However, the optical information recording medium proposed in JP-A-2006-147135, which has the interlayer composed of the Ta compound, the Nb compound, or the composite oxide containing Ta and/or Nb such as a composite oxide containing 70 atm % of Nb2O5 and 30 atm % of Al2O3, has the following disadvantages. Specifically, the electric conductivity of a target of the composite oxide containing 70 atm % of Nb2O5 and 30 atm % of Al2O3 is changed depending on the oxygen deficiency state of the target. For example, in a case where the target has no oxygen deficiency, the target is a perfect insulator, whereby the interlayer can be formed by the RF sputtering method using the target only at a low film formation speed on the dye-containing recording layer. Thus, in this case, the optical information recording medium cannot be easily produced, and cannot be practically used in view of the production. On the other hand, in a case where the target has oxygen deficiency and thereby has electric conductivity, abnormal discharge is often caused between the target and the interlayer in an RF sputtering machine under a high-frequency voltage applied between a vacuum chamber and the target. In this case, a groove-like scratch is generated on a surface of the interlayer composed of the composite oxide due to the abnormal discharge, and is found as an appearance failure in the optical information recording medium after forming the cover layer. Furthermore, immediately before and after the abnormal discharge, the voltage applied to the target is changed, whereby the interlayer cannot be formed at a constant speed, the resultant interlayer has an uneven film state, and the optical information recording medium cannot be stably produced.


The purpose of the present invention is to provide a display device that has a simple configuration and small power consumption. A display device of the present invention has: source output amplifiers (36) fewer in number than a plurality of source signal lines (S); and a switching unit (32) that supplies data signals outputted from each of the source output amplifiers (36) to one of the source signal lines (S). Each of the source output amplifiers (36) outputs the data signals having different polarities to the source signal lines (S) adjacent to each other, and outputs the data signals by switching, by each frame period, the polarities of the data signals to be supplied to the source signal lines (S).

Recently, display devices with thin-profile, light-weight, and low power consumption such as liquid crystal display devices are widely used. Such display devices are mainly used for mobile phones, smartphones, PDAs (personal digital assistants), electronic books, laptop personal computers, and the like, for example. Also, electronic paper, which is an even thinner display device, is expected to be developed and put in practical use rapidly in the coming years.
An active matrix mode is used in many such display devices. In general, the display screen of an active matrix display device is constituted of a plurality of pixels disposed in a grid pattern. Corresponding to these pixels, the display device includes a plurality of gate signal lines for sequential selection of a plurality of rows of pixels, and a plurality of source signal lines for supplying a source signal to the respective pixels of the selected row of pixels. By having an analog amp (hereinafter referred to as a "source output amplifier") included in a source driver supply a data signal (hereinafter referred to as a "source signal") as image data to the respective plurality of source signal lines, source signals are written to the respective pixels of a selected row of pixels.
Thus, as disclosed in Patent Document 1 below, for example, in a conventional display device, a plurality of source output amplifiers are provided in the source driver for respective source signal lines. A configuration is used such that when supplying source signals to the respective plurality of source signal lines, every time the source signal line to be supplied a source signal is switched, the source output amplifier to be used is switched to the source output amplifier that is paired with the source signal line. If the resolution of the display device is 1366×768, for example, then the source driver includes 1366 source output amplifiers.