Patents Examined by Huy Kim Mai
  • Patent number: 4917472
    Abstract: A liquid crystal cell useful in light valves is disclosed in which positive anisotropy liquid crystals are installed at an initial off-perpendicular alignment within the approximate range of A light valve employing the cell is initially biased to a voltage approximately corresponding to a transmissivity peak; the selection of the exact bias voltage involves a trade-off between contrast and response speed. The cell surfaces are characterized by generally flat macrostructures and tilted surface microstructures, with an overcoat on the surfaces of a long chain alcohol with alkoxy groups derived therefrom bonded to the tilted surface microstructure. The alcohol molecules have the formula ROH, where R is a carbon chain having at least six carbon atoms therein.
    Type: Grant
    Filed: March 14, 1988
    Date of Patent: April 17, 1990
    Assignee: Hughes Aircraft Company
    Inventors: John D. Margerum, Anna M. Lackner
  • Patent number: 4900132
    Abstract: A liquid crystal cell (10) includes a chiral liquid crystal material (16) captured between a pair of electrode structures (12 and 14). The liquid crystal material is of a type that exhibits in consecutive order chiral semitic nematic, smectic A, and chiral phases at successively lower temperatures. In a preferred embodiment, the chiral phase is of the smectic C type. The electrode structures have director alignment layers (22 and 22') deposited on their inner surfaces. The directors (28 and 30) of the liquid crystal material in the nematic phase in contact the alignment layers align at relatively large tilt bias angles relative to the alignment layer. The tilt bias angles of the directors in contact with one of the electrode structures are defined in a rotational sense which is opposite that of the tilt bias angles of the directors in contact with the other electrode structure.
    Type: Grant
    Filed: August 19, 1988
    Date of Patent: February 13, 1990
    Assignee: Tektronix, Inc.
    Inventor: Philip J. Bos
  • Patent number: 4896947
    Abstract: A liquid crystal display (LCD) cell comprising a twist nematic liquid crystal disposed between two electrode plates and polarizers and having a positive dielectric anisotropy. The optical path difference .DELTA.n.d is 0.2 to 0.7 .mu.m. The absolute value of the twist angle .phi. can be between and, the angle .psi. between the polarizers can be between and and the angle .theta. between the surface orientation direction and the polarization direction on the screen on the light incidence side can be between and, preferably so that the polarizers are symmetrical of the nematic directors.
    Type: Grant
    Filed: June 14, 1989
    Date of Patent: January 30, 1990
    Assignee: Hoffman-La Roche Inc.
    Inventor: Frans Leenhouts
  • Patent number: 4890009
    Abstract: A monolithic integrated circuit device comprises first and second output terminals, a power switching circuit which is connected across the first and second output terminals and through which electric current is supplied to an external load from an external power source, a driving a circuit for generating a first drive signal to be supplied to the power switching circuit, and a third output terminal in electrical connection with the driving circuit for derivation of electric energy from the driving circuit as a second drive signal to be spplied to an external circuit via the third output terminal. The monolithic integrated circuit device is capable of not only controlling power supply to an external load but also driving an external circuit which may be another power switching cirtcuit cooperative with the power switching circuit in the present monolithic integrated circuit device for the purpose of controlled power supply to the external load or which may be other types of electronic circuits.
    Type: Grant
    Filed: April 25, 1988
    Date of Patent: December 26, 1989
    Assignee: Hitachi, Ltd.
    Inventors: Hideki Miyazaki, Kenichi Onda, Yasuo Matsuda
  • Patent number: 4888502
    Abstract: A variable bandwidth filter comprises a transistor long-tailed pair. One of the transistors of the pair has a field effect transistor which is connected in the collector circuit of the transistor and which is used as a variable collector load resistor. The field effect transistor is shunted by a capacitor and the gate of the field effect transistor is fed with a control voltage via a feed-back control loop arrangement which serves to maintain constant the d.c. voltage across the field effect transistor whereby the effective bandwidth of a filter circuit defined between the base of the said one transistor is arranged to be controllable in dependence upon the current in the common tail of the pair as determined by a variable current source connected in the tail.
    Type: Grant
    Filed: February 1, 1988
    Date of Patent: December 19, 1989
    Assignee: Plessey Overseas Limited
    Inventor: Adrian E. Jarrett
  • Patent number: 4886344
    Abstract: A suitable choice of the liquid crystal parameters K.sub.3 /K.sub.1 and .DELTA.E/E.sub.1 makes it possible in electrooptical display elements to obtain both a minimum dependence on the angle of observation and, simultaneously, a steep electro-optical characteristic when operated in the first transmission minimum.
    Type: Grant
    Filed: August 19, 1988
    Date of Patent: December 12, 1989
    Assignee: Merck Patent Gesellschaft mit beschrankter Haftung
    Inventors: Bernhard Scheuble, Gunter Baur, Waltraud Fehrenbach
  • Patent number: 4883991
    Abstract: A circuit arrangement for amplifying a periodic signal and for adjusting a reference level contained therein, in which a charging/discharging arrangement alternately supplies charging or discharging currents to a storage means, depending on whether the value of a periodic signal exceeds or is exceeded by a limit value, such that a mean value at least substantially corresponding to the reference level occurs at the storage means includes a compensator means which adjusts the charging and disharging currents by a compensation factor which is selected such that the ratio of the charging current to the discharging current is independent of fluctuations in current resulting from variations affecting the gain factors of amplifier components comprised in the amplifier means.
    Type: Grant
    Filed: June 4, 1987
    Date of Patent: November 28, 1989
    Assignee: U. S. Philips Corporation
    Inventors: Klaus G. Kroner, Jorg Wolber
  • Patent number: 4877309
    Abstract: A color liquid crystal display device is composed of first and second liquid crystal display cells aligned over each other, in which each cell includes a pair of color polarizers having respective polarization axes which are oriented at right angles to each other. The color polarizers of each cell contain at least one color which is the complement of the color contained in the other color polarizer. In this way, display contrast and brightness can be enhanced by allowing a higher ratio of picture elements to be utilized for monochromatic displays.
    Type: Grant
    Filed: December 8, 1987
    Date of Patent: October 31, 1989
    Assignee: Sharp Kabushiki Kaisha
    Inventor: Toshiaki Takamatsu
  • Patent number: 4877310
    Abstract: A liquid crystal birefringent MTF filter is permanently positioned between lens and array of an image input scanner to reduce image modulation at frequencies where moire occurs, with a source of electric potential and a control switch for selectively applying the potential and switching the filter to or from a filtering state. In a variation of the first embodiment, a two-stage MTF filter is used. In a second embodiment, a tunable liquid crystal scattering MTF filter is combined with a full width sensor array.
    Type: Grant
    Filed: August 4, 1988
    Date of Patent: October 31, 1989
    Assignee: Xerox Corporation
    Inventors: Ned J. Seachman, Joseph P. Taillie, Gary A. Dir
  • Patent number: 4877979
    Abstract: A fitter comprising a first (R.sub.1) and a second (R.sub.2) resistor arranged in series between an input terminal (5) for receiving an input voltage (v.sub.i) and the input (2) of an amplifier. The amplifier (1) comprises a transistor (T.sub.1) whose base is coupled to the input (2), whose emitter is coupled to a first output (3) and via a current source (I.sub.1) to ground, and whose collector is coupled to a second output (4) and via a third resistor (R.sub.3) to the positive power-supply terminal. A first capacitor (C.sub.1) is arranged between the junction point (6) between the first resistor (R.sub.1) and the second resistor (R.sub.2) and the first output and a second capacitor (C.sub.2) is arranged between the input (2) and ground. A signal having a second-order low-pass characteristic is taken from the first output and a signal having a second-order high-pass characteristic is taken from the second output.
    Type: Grant
    Filed: November 30, 1987
    Date of Patent: October 31, 1989
    Assignee: U.S. Philips Corporation
    Inventor: Adrianus Sempel
  • Patent number: 4874965
    Abstract: A power-on reset circuit for supplying a reset pulse when a supply voltage rises above a preset threshold includes a reference voltage generator connected between the supply voltage and ground for supplying a reference signal having a constant preset value when the supply voltage is greater than the preset threshold. A supply follower provides an input signal which follows the supply voltage with a preset reduction factor. A bistable comparator having a first input driven by the reference signal and a second input driven by the input signal switches from a first state to a second state when the input signal exceeds the reference signal.
    Type: Grant
    Filed: November 25, 1987
    Date of Patent: October 17, 1989
    Assignee: SGS Microelettronica S.p.A.
    Inventors: Giovanni Campardo, David Novosel
  • Patent number: 4872742
    Abstract: An imaging system for maintaining the intensity of an output image constant, where the output image corresponds to a viewed scene. A focusing device forms an input image of the viewed scene on a variable grating modulation device. The viewed scene is then read from the focusing device and a scene intensity distribution pattern formed of two histograms is formed. One of these histograms is processed to produce an output image which has a constant range of intensity levels as adjusted using one of the intensity level of the one histogram.
    Type: Grant
    Filed: July 24, 1987
    Date of Patent: October 10, 1989
    Assignee: British Aerospace Public Limited Company
    Inventors: Henry J. White, Christopher Stace
  • Patent number: 4868414
    Abstract: For a plurality of logic units which are organized into scan-path groups, a scan-path self-testing circuit is provided which comprises a clock source and a plurality of gates for supplying the clock pulse to the logic units when selectively enabled. To give flexibility to group organization of the logic units, the gates are provided in a one-to-one relationship with the logic units. Bit positions of a register are associated respectively with the gates. A scan path controller selects one of the scan-path groups and writes a logic 1 into the register bit positions which are associated with the logic units of the selected scan-path group.
    Type: Grant
    Filed: February 26, 1988
    Date of Patent: September 19, 1989
    Assignee: NEC Corporation
    Inventor: Takashi Kanazawa
  • Patent number: 4868514
    Abstract: This disclosure concerns digital correction of oscillator drift by providing phase alignment between two clock signals running at nearly the same frequency. Phase alignment is provided by fashioning a delay for one of the clock signals through selection of various lengths of a variable delay path formed from a series of logic circuits. Respective reference signals are derived from the two clocks to be phase-aligned, and the phases of the references are compared in a digital phase comparator. The product of phase comparison controls a digital delay selector to generate a sequence of delay signals corresponding to a sequence of detected phase differences. The delay signal sequence controls the variable digital delay. The variable digital delay outputs a corrected clock signal whose phase is aligned with the phase of the other clock signals. The corrected clock signal is used to produce one reference signal, the other reference signal being derived directly from the other clock signal.
    Type: Grant
    Filed: November 17, 1987
    Date of Patent: September 19, 1989
    Assignee: International Business Machines Corporation
    Inventors: Michael J. Azevedo, Charles A. Corchero, Donald J. Lang, Gilbert R. Woodman, Jr.
  • Patent number: 4868511
    Abstract: A digital sequencing apparatus produces a series of contiguous enable gates or strobe signals. The apparatus includes an even number, and at least two alternating stages of cross-coupling NOR gates alternating with cross-coupled NAND gates where one of the cross-coupled NOR gates in each stage has a merged AND gate at one input and one of the NAND gates in each stage has a cross-coupled OR gate at one input. This apparatus produces contiguous enable gates in response to complementary clock inputs to each of the stages upon the input of a start signal to the first two stages of the apparatus.
    Type: Grant
    Filed: February 22, 1988
    Date of Patent: September 19, 1989
    Assignee: Hughes Aircraft Company
    Inventor: George S. Des Brisay. Jr.
  • Patent number: 4861143
    Abstract: A liquid crystal display of the chiral smectic type is caused to have grey scales, by applying a voltage of an intermediate level to the liquid crystal. Within each picture element of the display, there are a number of domains of the liquid crystal layer, some being transparent while the other being opaque rendering grey tone to the picture element.
    Type: Grant
    Filed: December 2, 1987
    Date of Patent: August 29, 1989
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Shunpei Yamazaki, Takashi Inujima, Toshimitsu Konuma, Toshiji Hamatani, Akira Mase, Mitsunori Sakama, Minoru Miyazaki, Kaoru Koyanagi, Toshiharu Yamaguchi
  • Patent number: 4861142
    Abstract: Light emitted from a single light source is split into beams of bidirectional parallel light which are orthogonal to each other. Beams of the parallel light in each direction are reflected by a reflection optical system in such a direction that they become orthogonal to each other. A dichroic mirror is disposed at a point of intersection thereof and liquid crystal panels are provided between each individual reflection optical system and the dichroic mirror resulting in a low cost device which can be structurally miniaturized and which requires less process steps in fabrication.
    Type: Grant
    Filed: May 12, 1987
    Date of Patent: August 29, 1989
    Assignee: Seikosha Co., Ltd.
    Inventors: Sakae Tanaka, Tadahiko Yamaoka, Shingo Takahashi, Tomoaki Takahashi
  • Patent number: 4862097
    Abstract: A pulsating noise removal device detects a pulsating noise, controls a gate circuit for selectively permitting an audio signal to pass through in response to the detection, and removes pulsating noises from the audio signal. The device particularly includes filter circuits for extracting pulsating noises and signal components from the audio signal, respectively, and includes automatic gain control circuits responsive to respective output signals of the filter circuits to respectively control the gain of an amplifier circuit for detecting pulsating noises.
    Type: Grant
    Filed: January 19, 1988
    Date of Patent: August 29, 1989
    Assignee: Clarion, Co., Ltd.
    Inventors: Kiyoshi Amazawa, Akira Mori
  • Patent number: 4859881
    Abstract: A double integration type filter circuit, consisting of a pair of integrators connected in series with each other, has a changeover switch for commutating the filter characteristics to a filter configuration which emphasizes portions proper to the characteristics of the filter circuit to facilitate filter adjustment to reduce filter adjustment time and to realize improved accuracy while providing for automatic adjustment of the filter characteristics.
    Type: Grant
    Filed: December 29, 1987
    Date of Patent: August 22, 1989
    Assignee: Sony Corporation
    Inventors: Yoshihiro Yamamoto, Tsutomu Kume, Nobuo Yamazaki, Fumiharu Hashimoto, Koichi Ohya
  • Patent number: 4859034
    Abstract: The optical printing apparatus comprises a fluorescent lamp light source and a means for concentrating light from the light source onto a liquid crystal panel. The liquid crystal panel includes a plurality of light valves disposed in rows. A driver is disposed on the outside of the shield plate for selectively opening and closing the light valves. Rows of self-focusing fiber lenses receive light from the light valves and direct the light onto a photosensitive drum for use in printing.
    Type: Grant
    Filed: May 9, 1986
    Date of Patent: August 22, 1989
    Assignee: Seiko Epson Corporation
    Inventors: Yoshiaki Shiraishi, Kenji Aoki