Sharp Kabushiki Kaisha Corporation

Other

Takao Tagawa

Noritoshi Kako

Kengo Takahama

Masayuki Katagiri

Kenichi Morimoto

Hitoshi Nohno

Kiyohiro Nozaki

Kazunari Okamura

Yoshiyuki Nakai

Toshio Nomura

Yasuhiro Yoshida

Toshio Urakawa

Etsuzi Nukushina

Yasuhiro Takai

Hiroshi Yoneda

Hiroshi Tsujioka

Shigeru Shibazaki

Shigekazu Yoshida

Shiro Taga

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. This step of displaying one frame includes the step of applying to the second electrodes second direction drive signals of predetermined waveforms in accordance with a predetermined order at timings shifted from each other, applying to the first electrodes first direction drive signals of waveforms corresponding to display intensities of pixels, respectively, thereby performing gray scale image display on each pixel, and simultaneously detecting the position of the electronic pen in the first direction based on a waveform of an induced voltage induced at the electronic pen by the second electrode located near the electronic pen; and the step of applying a voltage for position detection to the first electrodes in accordance with the predetermined second order, and detecting a position of the electronic pen in the second direction based on an induced voltage induced at the electronic pen by the voltage for the position detection.

Method of detecting a position indicated by an electronic pen in a

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. Furthermore, there is no need to form a closed loop in the electrodes of the LCD panel, which obviates the need of providing any board opposite to four sides of the LCD panel.

Coordinate detection device capable of detecting coordinates using

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.

Coordinate input device used for inputting characters and drawings into

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. Since a Y-coordinate detection signal is detected in this manner, it becomes possible to increase an induced voltage to be exerted in a detection electrode of an electronic pen, to improve the S/N ratio of the Y-coordinate detection signal, and also to enhance the detection accuracy of the Y-coordinate.

Display-integrated type tablet device

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. Furthermore, there is no need to form a closed loop in the electrodes of the LCD panel, which obviates the need of providing any board opposite to four sides of the LCD panel.

Coordinate detection device capable of obviating the need of forming

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.

Portable projection display apparatus

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. The coordinate input section includes: a plurality of coordinate input electrodes arranged in a matrix on the first substrate; signal lines, formed on the first substrate, for supplying coordinate determination signals to the coordinate input electrodes, respectively; active elements for electrically connecting the coordinate input electrodes to the signal lines, respectively; a coordinate designating member for, when the coordinate designating member is brought near the first substrate, forming an electrostatic capacitance with at least one of the coordinate input electrodes; and a coordinate determination circuit for receiving the coordinate determination signal from the coordinate input electrode, and for determining the coordinates of a point to which the coordinate designating member comes closer, based on the received coordinate determination signal.

Reflection type input/output liquid crystal display

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. A correction signal generation circuit reads out correction data stored in an internal memory and transmits the data as a correction signal to a correction voltage generation circuit in an x-coordinate detection period when the segment electrode placed in the lower position is scanned. The correction voltage generation circuit generates a correction voltage for canceling a voltage induced at the common electrode placed in the upper position based on the input correction signal and a bias power source input from a DC power supply circuit.

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. Thus, there is provided a display-integrated type tablet device into which display function has been integrated, in order to make the image easy-to-view and the device itself more compact, less costly.

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.

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.

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. Thus a waveform of a voltage induced at a detection electrode of a detection pen in an x-coordinate detection period and a waveform of a voltage induced in a y-coordinate detection period are made approximately equal to each other to obtain a high coordinate detection accuracy.

Display-integrated type tablet device having and idle time in one

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.

Display-integrated type tablet device capable of detecting correct

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. Thus brightness data of the document, position data of the input pen, and image data corresponding to a display signal are written into the image input device-integrated type display unit.

Growing community of inventors

Kashihara, Japan

Takao Tagawa