Patents by Inventor Katsuhiko Kumagawa

Katsuhiko Kumagawa has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Publication number: 20020154084
    Abstract: An active matrix type display apparatus is provided that is inexpensive, has less crosstalk, has no flickering and a brightness gradient, and is suitable for a large screen size. The display apparatus includes a plurality of pixel electrodes arranged in a matrix, switching elements (TFTs) connected thereto, scanning electrodes, video signal electrodes, common electrodes, and a counter electrode, wherein liquid crystal, for example, is interposed between the pixel electrodes and the counter electrode. Assuming that a gate-drain capacitance is Cgd, a common electrode-pixel electrode capacitance is Cst, and the total capacitance connected to the pixel electrodes is Ctot in this configuration, &agr;gd and &agr;st represented by &agr;gd=Cgd/Ctot, &agr;st=Cst/Ctot are set to be different values between a portion close to feeding ends in a screen and a portion away therefrom.
    Type: Application
    Filed: February 13, 2002
    Publication date: October 24, 2002
    Inventors: Yukio Tanaka, Katsuhiko Kumagawa, Masanori Kimura, Kazunori Komori
  • Publication number: 20020149576
    Abstract: Disclosed is a display capable of improving uniformity of luminance and chroma in a plane of a display panel. When point at which the light source is turned ON is represented by T1, transmittance in a display region onto which the video signals are being written at the point T1 is represented by M1. point at which the light source is turned OFF is represented by T2, transmittance in the display region onto which the video signals are being written at point T2 is represented by M2, a maximum value of the transmittance in the display region of the light modulation element in a period during which the light source is ON is represented by M0, and the write period is represented by Twrite, the illuminating device control portion is adapted to control the illuminating device so as to satisfy a formula given by [|M2−M1|Twrite]/[M0(T2−T1)]≦0.92.
    Type: Application
    Filed: March 28, 2002
    Publication date: October 17, 2002
    Inventors: Yukio Tanaka, Masanori Kimura, Takashi Okada, Katsuhiko Kumagawa
  • Publication number: 20020140691
    Abstract: At the time when displaying moving images using liquid crystal panels and others, there is such a problem that tail streaks occur, and resultantly image degradation is caused. In order to solve this problem, an echo suppression circuit 100 divides a video signal into a pair composed of two successive frames for comparison between these two frames in signal level for the purpose of suppressing an echo phenomenon occurring when a liquid crystal panel 108 displays video signals including moving images. If these two frames are not the same in signal level, the signal is accordingly so corrected as to equalize the signal level of those. Based on the video signals and others corrected by the echo suppression circuit 100, a controller 102 operates the liquid crystal panel with Alternating-Current drive through a source driver 104 and a gate driver 106. As such, the drive voltage used to operate the liquid crystal panel with AC drive is so adjusted as to be balanced between positive and negative.
    Type: Application
    Filed: February 7, 2002
    Publication date: October 3, 2002
    Inventors: Ichiro Sato, Katsuhiko Kumagawa, Kazuo Inoue, Taro Funamoto, Wataru Machidori, Katsuyuki Arimoto
  • Publication number: 20020113913
    Abstract: An active matrix liquid crystal display element capable of reducing flicker comprises: a plurality of source lines; a plurality of gate lines arranged so as to intersect the plurality of source lines in a plan view, for transmitting a gate signal; a plurality of pixels defined by the plurality of source lines and the plurality of gate lines, constituting an image display plane; a pixel electrode provided for every pixel; an opposed electrode facing the pixel electrode across a liquid crystal layer; a storage capacitor for holding a voltage applied between its corresponding pixel electrode and the opposed electrode; and a pixel transistor having a source electrode, a drain electrode and a gate electrode which are connected to a corresponding one of the source lines, a corresponding one of the pixel electrodes and a corresponding one of the gate lines respectively, and being turned ON or OFF by the gate signal, wherein an index B given by B=Lst/Lgd is equal to or greater than 7, where a periphery length
    Type: Application
    Filed: January 30, 2002
    Publication date: August 22, 2002
    Inventors: Takashi Okada, Yukio Tanaka, Masanori Kimura, Katsuhiko Kumagawa
  • Publication number: 20020012077
    Abstract: This is an active matrix liquid crystal display device comprising a capacitive accumulation portion formed by overlapping a pixel electrode, an insulating layer and a common electrode for each pixel area, and a non-electrode area in a part of the pixel area which is not covered with a pixel electrode, wherein a peripheral shape of said capacitive accumulation portion on a side contacting said non-electrode area is substantially the same between the respective pixels, and a value of a storage capacity in said capacitive accumulation portion differs on a feeding side and on a termination side, the value on the feeding side being larger than the value on the termination side. Thereby, a constant aperture ratio can be maintained by changing the storage capacity value for each pixel.
    Type: Application
    Filed: July 23, 2001
    Publication date: January 31, 2002
    Applicant: Matushita Electric Industrial Co., Ltd.
    Inventors: Tetsuo Fukami, Katsuhiko Kumagawa, Masanori Kimura
  • Patent number: 6232944
    Abstract: A compact and inexpensive LCD is provided by improving a drive method for compensating a crosstalk using a compensating pulse added to a signal voltage so that a drive IC and a periphery of the LCD panel are reduced in size. Only one of positive and negative compensating pulses is added in accordance with a predetermined period. Alternatively, the two compensating pulses are added at different times from each other in one horizontal scanning period. The compensating pulse preferably has a waveform including low frequency components. A width or a height of the compensating pulse varies in accordance with a location of the signal electrode, display pattern or other factors.
    Type: Grant
    Filed: April 4, 1997
    Date of Patent: May 15, 2001
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Katsuhiko Kumagawa, Akira Kawaji, Masahito Matsunami, Takeshi Okuno, Tohru Suyama
  • Patent number: 5748276
    Abstract: A liquid crystal display unit including a plurality of subpixels in each pixel provides superior gradation over a wide viewing angle, and is produced with no increase in manufacturing cost and no deterioration of desired properties (such as reduction in brightness, contrast and response). No additional manufacturing step is required since a control capacitor electrode is formed at the same time as source and drain electrodes constituting a thin-film transistor. By controlling the ratio of display area and the difference in applied voltage of the subpixels, preferable viewing angle properties are obtained. The display properties at the boundary of subpixels are improved by controlling the gap width and the direction of boundary of the subpixels, thus providing a bright display.
    Type: Grant
    Filed: December 9, 1996
    Date of Patent: May 5, 1998
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Mitsuhiro Uno, Yoneharu Takubo, Katsuhiko Kumagawa, Satoshi Asada, Naomi Takada
  • Patent number: 5610739
    Abstract: A liquid crystal display unit including a plurality of subpixels in each pixel provides superior gradation over a wide viewing angle, and is produced with no increase in manufacturing cost and no deterioration of desired properties (such as reduction in brightness, contrast and response). No additional manufacturing step is required since a control capacitor electrode is formed at the same time as source and drain electrodes constituting a thin-film transistor. By controlling the ratio of display area and the difference in applied voltage of the subpixels, preferable viewing angle properties are obtained. The display properties at the boundary of subpixels are improved by controlling the gap width and the direction of boundary of the subpixels, thus providing a bright display.
    Type: Grant
    Filed: May 25, 1995
    Date of Patent: March 11, 1997
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Mitsuhiro Uno, Yoneharu Takubo, Katsuhiko Kumagawa, Satoshi Asada, Naomi Takada
  • Patent number: 5166817
    Abstract: A liquid crystal display comprises as liquid crystal panel having a liquid crystal layer disposed between electrode layers, polarizers disposed at both sides of the panel, and a solid birefringent film having the maximum refractive index direction varying with its depth and disposed at at least one side of the liquid crystal panel between the polarizers. The solid birefringent film conpensates the dependence of the polarization characteristic on wave length, thus being capable of obtaining either a monochrome display or a display having an extremely low coloration.
    Type: Grant
    Filed: October 6, 1988
    Date of Patent: November 24, 1992
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Isao Ota, Katsuhiko Kumagawa, Shingo Fujita, Hiroshi Yamazoe, Shigeru Yoshida, Toshio Tatsumichi
  • Patent number: 4775549
    Abstract: A method of producing a substrate structure for a large size display panel. The method involves conveying a transparent substrate from a transparent substrate storage means in a conveying path through a vacuum chamber, and while conveying the substrate, forming at least a patterned transparent conductive film on a surface of the substrate by depositing strips of conductive film on the substrate through a pattern containing member extending in a direction orthogonal to the substrate conveying direction and having strip forming openings therein at intervals along the lengths thereof, and storing the transparent substrates with the strips thereon at the end of the conveying path.
    Type: Grant
    Filed: December 19, 1985
    Date of Patent: October 4, 1988
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Isao Ota, Toshio Tatsumichi, Katsuhiko Kumagawa, Hiroshi Yamazoe, Masahiro Nagasawa