Patents by Inventor Takao Tagawa

Takao Tagawa 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).

  • Patent number: 6091030
    Abstract: In a display-integrated panel having first and second electrodes crossing each other and being operable to display a gray scale image, a position indicated by an electronic pen is detected by a method including the step of displaying information on a display panel by repeating a step of displaying one frame.
    Type: Grant
    Filed: November 13, 1997
    Date of Patent: July 18, 2000
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Takao Tagawa, Masayuki Katagiri, Shiro Taga, Shigeru Shibazaki
  • Patent number: 5854881
    Abstract: Provided is a coordinate detection device capable of preventing the increase of development cost and the reduction of yield and dispensing with additional investment for the existing equipment. There are provided an LCD panel having electrodes and electrodes, a magnetic field generator which outputs an AC magnetic field from a tip end of its electrode, a differential amplifier, switching circuits which sequentially select electrodes of the LCD panel and connect the electrodes to the differential amplifier, and a coordinate detection circuit which detects the coordinates of a position in which the magnetic field generator is located based on a timing at which the electrodes are selected and an output of the differential amplifier. A coordinate detection function can be achieved by means of the LCD panel having the same structure as that of the LCD panel provided specially for image display.
    Type: Grant
    Filed: May 19, 1995
    Date of Patent: December 29, 1998
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Yasuhiro Yoshida, Kengo Takahama, Takao Tagawa
  • Patent number: 5854448
    Abstract: A coordinate input device includes (1) a pen switch sensing circuit for providing a power supply to a pen switch in a position sensing pen, and for sensing that the pen switch is turned on and off and (2) a pen switch control circuit for controlling a timing of the power supply. The power supply is provided to the pen switch only when coordinate sensing operations are not affected. The power supply is stopped in order to avoid a voltage change happening to the pen switch when the coordinate sensing operation is affected. Therefore, the pen switch is neither turned on nor turned off during a coordinate sensing period. Consequently, it is possible to avoid a wrong sensing of a coordinate indicated with the position sensing pen.
    Type: Grant
    Filed: April 8, 1996
    Date of Patent: December 29, 1998
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Kiyohiro Nozaki, Takao Tagawa
  • Patent number: 5825345
    Abstract: During a display period (Y-coordinate detection period), an image is written to an electro-optical material so as to form a display by driving row electrodes and column electrodes by using a row-electrode driving circuit and a column-electrode driving circuit so as to selectively operate TFTs. In this case, a shift data signal having a width corresponding to two clocks of a horizontal sync signal is supplied to the row-electrode driving circuit by using a start-pulse-width expanding circuit; therefore, two row-electrode scanning signals are simultaneously inputted to two of the corresponding row electrodes. Moreover, the row-electrode scanning signals have periods in which they instantaneously turn "off" respectively, and the turning-off timing is coincident in the respective signals.
    Type: Grant
    Filed: August 1, 1996
    Date of Patent: October 20, 1998
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Kengo Takahama, Takao Tagawa, Kiyohiro Nozaki
  • Patent number: 5798756
    Abstract: There is provided a coordinate detection device capable of preventing increase of development cost and reduction of yield and dispensing with additional investment for existing equipment. The coordinate detection device includes an LCD panel having electrodes and electrodes, an electric field generator which outputs an AC electric field from a tip end of its electrode, a differential amplifier, switching circuits which sequentially select electrodes of the LCD panel and connect the selected electrodes to the differential amplifier, and a coordinate detection circuit which detects coordinates of a position in which the electric field generator is located based on a timing at which the electrodes are selected and an output of the differential amplifier. A coordinate detection function can be achieved by means of the LCD panel having the same structure as that of an LCD panel provided specially for image display.
    Type: Grant
    Filed: June 2, 1995
    Date of Patent: August 25, 1998
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Yasuhiro Yoshida, Kengo Takahama, Takao Tagawa
  • Patent number: 5738429
    Abstract: The present projection display apparatus includes an illumination source, an LCD panel including a polarizing plate, a light projecting and receiving combinational lens, a screen, a light pen, a detection-use polarizing plate, a CCD, and a control circuit for controlling an operation of the LCD panel upon receiving a signal from the CCD. The combinational lens throws light of a display image from the LCD panel to project the light on the screen. Meanwhile, the lens receives light from the display image and luminescent spot light from the pen to focus them on the LCD panel and then reflect the same to make them incident on the CCD via the detection-use polarizing plate. The detection-use polarizing plate does not transmit the light of the display image.
    Type: Grant
    Filed: June 5, 1995
    Date of Patent: April 14, 1998
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Takao Tagawa, Masayuki Katagiri, Hitoshi Nohno
  • Patent number: 5677744
    Abstract: The display apparatus of the invention includes: a first substrate and a second substrate which are disposed so as to face each other; a display medium having variable optical characteristics sandwiched between the first substrate and the second substrate; a display circuit provided on the first substrate; and a coordinate input section for inputting coordinates of a point on the first substrate.
    Type: Grant
    Filed: April 28, 1994
    Date of Patent: October 14, 1997
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Hiroshi Yoneda, Hiroshi Tsujioka, Takao Tagawa
  • Patent number: 5631666
    Abstract: A detection and hold circuit outputs a reference signal having a level proportional to an x-coordinate detection pulse input from an X-coordinate signal amplifier. A delay element delays the reference signal. An adder adds the x-coordinate detection pulse from the X-coordinate signal amplifier and a delayed signal from the delay element. Comparators obtain a coordinate detection pulse making a detection signal from another detection and hold circuit for an LCD voltage inversion pulse serve as a reference signal. Thus noise following the x-coordinate detection pulse is removed to generate a coordinate detection pulse with a reference value corresponding to the level of the LCD voltage inversion pulse to allow a stable coordinate detection to be achieved.
    Type: Grant
    Filed: January 13, 1995
    Date of Patent: May 20, 1997
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Takao Tagawa, Kengo Takahama, Kazunari Okamura, Noritoshi Kako
  • Patent number: 5592197
    Abstract: A switching circuit 7 switchedly selects the side of a detection control circuit 6 for the coordinate detection period in compliance with control of a control circuit 10. Then according to each signal from the detection control circuit 6, a segment drive circuit 3 generates a segment electrode scan signal to scan segment electrodes X of a liquid crystal panel 1 in turn. Subsequently, a common drive circuit 2 generates a common electrode scan signal to scan common electrodes Y in turn. An x-coordinate detection circuit 8 and a y-coordinate detection circuit 9 detects the x- and y-coordinates of the tip of an electronic pen 11 on the basis of an induced voltage developed to a tip electrode of the electronic pen 11. During the display period, the side of a display control circuit 4 is switchedly selected, displaying an image onto the liquid crystal panel 1.
    Type: Grant
    Filed: July 14, 1994
    Date of Patent: January 7, 1997
    Assignee: Sharp Kabushiki Kaisha
    Inventor: Takao Tagawa
  • Patent number: 5581274
    Abstract: A display-integrated type tablet device provided with a liquid crystal display panel has a mode detection circuit. During the display period, the circuit receives electrostatically induced voltages developed on a detection pen and compares the received electrostatically induced voltage with a previously set reference voltage. If the electrostatically induced voltage is greater than the reference voltage, the mode detection circuit decides that a coordinate detection mode exists, while if the electrostatically induced voltage is smaller than the reference voltage a non-detection mode is determined.
    Type: Grant
    Filed: November 4, 1994
    Date of Patent: December 3, 1996
    Assignee: Sharp Kabushiki Kaisha
    Inventor: Takao Tagawa
  • Patent number: 5534886
    Abstract: Displacement between an actual designation position designated by a detection pen and a detection coordinates is corrected. A correction calculation section includes a plurality of processing mode determination modules, a propagation delay correction module, an inward displacement correction module, a waveform distortion correction module, and a periodical fluctuation correction module. The processing mode determination module determines a correction module according to a detection coordinate value input. Each of the correction modules includes a correction formula or a lookup table inherent to each area. According to the correction formula or the lookup table, input detection coordinate value is corrected to thereby correct the displacement between the actual designation position and the detection coordinate value.
    Type: Grant
    Filed: May 22, 1995
    Date of Patent: July 9, 1996
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Toshio Nomura, Takao Tagawa, Noritoshi Kako
  • Patent number: 5534892
    Abstract: There is provided a display-integrated type tablet device which can achieve a high coordinate detection accuracy even when an electrode density of electrodes is greater than a electrode density of the other electrodes in a display panel. A segment electrode scanning clock signal for scanning segment electrodes having an electrode density three times as high as that of common electrodes has a frequency three times as high as a common electrode scanning clock signal. Shift data input to a segment electrode drive circuit has the same pulse width as that of the shift data input to a common electrode drive circuit. As a result, a scanning speed in an x-direction (shift speed of a segment electrode scanning signal) can be made approximately equal to a scanning speed in a y-direction (shift speed of a common electrode scanning signal). Furthermore, the width of the segment electrodes in an active state is made equal to the width of the common electrode.
    Type: Grant
    Filed: February 28, 1994
    Date of Patent: July 9, 1996
    Assignee: Sharp Kabushiki Kaisha
    Inventor: Takao Tagawa
  • Patent number: 5491706
    Abstract: An induction voltage signal induced at a detection electrode of a detection pen is binarized by a slice voltage "e.sub.s ". The number of pulses existing in the binary signal is counted by a counting device. The resulting count value obtained by the counting device and the number of times of electrode scanning in an x-coordinate detection period or a y-coordinate detection period are compared with each other by means of a comparator. When the number of pulses is greater, an error detection alarm signal is output by an alarm device. Thus the existence of the pulses based on the error detection signal is detected in the binary signal based on the induction voltage signal from the detection electrode to output the error detection alarm signal. The above arrangement allows the coordinates at the tip end of the detection pen to be detected in a stable and correct manner even when external noise is detected.
    Type: Grant
    Filed: April 5, 1994
    Date of Patent: February 13, 1996
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Takao Tagawa, Hitoshi Nohno, Kiyohiro Nozaki, Kazunari Okamura
  • Patent number: 5442373
    Abstract: Displacement between an actual designation position designated by a detection pen and a detection coordinates is corrected. A correction calculation section includes a plurality of processing mode determination modules, a propagation delay correction module, an inward displacement correction module, a waveform distortion correction module, and a periodical fluctuation correction module. The processing mode determination module determines a correction module according to a detection coordinate value input. Each of the correction modules includes a correction formula or a lookup table inherent to each area. According to the correction formula or the lookup table, input detection coordinate value is corrected to thereby correct the displacement between the actual designation position and the detection coordinate value.
    Type: Grant
    Filed: May 19, 1993
    Date of Patent: August 15, 1995
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Toshio Nomura, Takao Tagawa, Noritoshi Kako
  • Patent number: 5430462
    Abstract: There is provided an image input device-integrated type display device concurrently having an image display function, a document image input function, and a pen input function. A common electrode of the image input device-integrated type display unit is formed on a glass plate. A segment electrode is formed on a micro lens of a glass plate. An island electrode located at each pixel is connected to the segment electrode via a photoconductor. Liquid crystals are interposed between the common electrode and the island electrode. In an image input mode, light reflected on a document is applied to the photoconductor to control a voltage applied to the liquid crystals. In a pen input mode, light from an input pen is applied to the photoconductor to control a voltage applied to the liquid crystals. In an image display mode, a voltage applied to the liquid crystals is controlled according to image data of each pixel.
    Type: Grant
    Filed: December 6, 1993
    Date of Patent: July 4, 1995
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Masayuki Katagiri, Takao Tagawa, Noritoshi Kako
  • Patent number: 5410329
    Abstract: A detection and hold circuit outputs a reference signal having a level proportional to an x-coordinate detection pulse input from an X-coordinate signal amplifier. A delay element delays the reference signal. An adder adds the x-coordinate detection pulse from the X-coordinate signal amplifier and a delayed signal from the delay element. Comparators obtain a coordinate detection pulse making a detection signal from another detection and hold circuit for an LCD voltage inversion pulse serve as a reference signal. Thus noise following the x-coordinate detection pulse is removed to generate a coordinate detection pulse with a reference value corresponding to the level of the LCD voltage inversion pulse to allow a stable coordinate detection to be achieved.
    Type: Grant
    Filed: May 21, 1993
    Date of Patent: April 25, 1995
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Takao Tagawa, Kengo Takahama, Kazunari Okamura, Noritoshi Kako
  • Patent number: 5392058
    Abstract: A multiplexer 13 selects the input terminal B side for a display period while it selects the input terminal A side for a coordinate detection period. A lower common drive circuit 2L, based on shift data transmitted from the multiplexer 13, operates in parallel with an upper common drive circuit 2U during the display period while it operates in series with the upper common drive circuit 2U during the coordinate detection period. An upper segment drive circuit 3U and a lower segment drive circuit 3L simultaneously operate to drive upper segment electrodes XU and lower segment electrodes XL simultaneously in the same direction. Thus, during the display period there is displayed an image simultaneously onto the upper half 1wU and the lower half 1wL of a display panel 1w, thereby improving the duty ratio of display.
    Type: Grant
    Filed: May 13, 1992
    Date of Patent: February 21, 1995
    Assignee: Sharp Kabushiki Kaisha
    Inventor: Takao Tagawa
  • Patent number: 5357266
    Abstract: A switching circuit 7 switchedly selects the side of a detection control circuit 6 for the coordinate detection period in compliance with control of a control circuit 10. Then according to each signal from the detection control circuit 6, a segment drive circuit 3 generates a segment electrode scan signal to scan segment electrodes X of a liquid crystal panel 1 in turn. Subsequently, a common drive circuit 2 generates a common electrode scan signal to scan common electrodes Y in turn. An x-coordinate detection circuit 8 and a y-coordinate detection circuit 9 detects the x- and y-coordinates of the tip of an electronic pen 11 on the basis of an induced voltage developed to a tip electrode of the electronic pen 11. During the display period, the side of a display control circuit 4 is switchedly selected, displaying an image onto the liquid crystal panel 1.
    Type: Grant
    Filed: March 11, 1992
    Date of Patent: October 18, 1994
    Inventor: Takao Tagawa
  • Patent number: 5331333
    Abstract: A display apparatus in which light outputted from an LED array arranged in a column is reflected by a vibrating mirror such that a two-dimensional image is obtained, comprising: a half mirror which reflects light having a wavelength identical with a light emitting wavelength of the LED array and transmits therethrough visible light having other wavelengths than the light emitting wavelength; the half mirror being so disposed as to not only transmit therethrough the visible light from outside but also reflect the light proceeding from the LED array via the vibrating mirror such that the two-dimensional image has an outer scene as its background.
    Type: Grant
    Filed: October 23, 1992
    Date of Patent: July 19, 1994
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Takao Tagawa, Hitoshi Nohno
  • Patent number: 5155615
    Abstract: A miniature display device formed in such a manner that a magnification lens is disposed between the vibration mirror and the observation position. Further light emitting elements are situated at the focus position of the magnification lens. Thus, a miniature display device is formed which is appropriate for use in a small-sized electronic apparatus such as a hand-held mini-computer.
    Type: Grant
    Filed: April 11, 1989
    Date of Patent: October 13, 1992
    Assignee: Sharp Kabushiki Kaisha
    Inventor: Takao Tagawa