JP2006085489A - Coordinate detecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coordinate detecting device speeding up a coordinate detecting rate. <P>SOLUTION: A coordinate detecting means 30 detects coordinates on a display panel indicated by a position indicator 210 by induced electromotive force generated in a first closed loop circuit and a second closed loop circuit. The coordinates are detected by the coordinate detecting means 30 by successively driving the first and second closed loop circuits in a coordinate detecting period, and an image rewriting period is shortened by rewriting only a picture element corresponding to the detected coordinates in an image rewriting period. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a coordinate detection apparatus, and relates to a coordinate detection apparatus using a matrix type display panel.

  Conventionally, an electromagnetic wave is emitted from a position indicator toward a matrix type display panel, and a position (coordinate) of the position indicator is detected by an induced electromotive force generated by the electromagnetic wave. As such a coordinate detection device, there is a display-integrated coordinate detection device in which gate lines and source lines of a matrix type display panel are shared by a display drive line and a coordinate detection drive line ( (See Patent Document 1).

  FIG. 11 is a diagram for explaining the configuration of such a conventional coordinate detection apparatus. In FIG. 11, reference numeral 111 denotes an electromagnetic induction type coordinate detection apparatus having an active matrix type liquid crystal panel 112.

  Here, the liquid crystal panel 112 which is a matrix type display panel has a plurality of gate lines G1 to Gn and a plurality of source lines S1 to Sm arranged so as to be orthogonal to each other. Gn and source lines S1 to Sm are formed on an active matrix substrate which is one of a pair of substrates (not shown) constituting the liquid crystal panel 112.

  Further, a switching element (hereinafter also referred to as a display switching element) 112a such as a TFT constituting the pixel is provided at the intersection of the gate lines G1 to Gn and the source lines S1 to Sm on the substrate. The gates of the switch elements (TFT) 112a are respectively connected to the gate lines G1 to Gn, and the sources of the switch elements (TFT) 112a are connected to the source lines S1 to Sm.

  Further, the drain of the display switch element 112a is connected to a pixel electrode (not shown) or the like, and the pixel electrode and a common electrode provided on a counter substrate which is the other substrate of the pair of substrates. Between them, a capacitor 112b is formed.

  The coordinate detection device 111 also includes a gate line driving circuit 113 that supplies a driving signal corresponding to the scanning signal to the gate lines G1 to Gn, and a source line driving that supplies a driving signal corresponding to the display data to the source lines S1 to Sm. The gate lines G1 to Gn and the source lines S1 to Sm are driven at a required timing by the gate line driving circuit 113 and the source line driving circuit 114, so that an image is displayed on the liquid crystal panel 112. Display is done.

  Further, the coordinate detection device 111 gates a first closed loop circuit including two gate lines positioned at a predetermined interval among the plurality of gate lines G1 to Gn from one end side to the other end side of the liquid crystal panel 112. A first closed loop forming unit that sequentially forms along the lines G1 to Gn and a second closed loop circuit including two source lines located at a predetermined interval among the plurality of source lines S1 to Sm Second closed loop forming means for sequentially forming along Sn.

  Here, the first closed loop forming means includes a gate line current detection circuit 115 that sequentially connects one end side (gate line driving circuit side) of two gate lines positioned at a predetermined interval to the amplifier circuit 117, and a gate line. A gate line switch circuit 119 that commonly connects the other end sides of G1 to Gn (the side opposite to the gate line driving circuit 113).

  The second closed loop forming means includes a source line current detection circuit 116 that sequentially connects one end side (source line drive circuit side) of two source lines positioned at a predetermined interval to the amplifier circuit 118, and source lines S1 to S1. It is composed of a source line switch circuit 1110 that commonly connects the other end side of Sm (the side opposite to the source line drive circuit 114).

  Note that the gate line driver circuit 113 and the gate line current detection circuit 115 have a portion that can be shared in terms of circuit configuration, and thus are formed in the same IC, that is, the gate line circuit 1111. Further, the source line driver circuit 114 and the source line current detection circuit 116 also have a portion that can be shared in terms of circuit configuration, and thus are formed in the same IC, that is, the source line circuit 1112. The amplifier circuits 117 and 118 are configured to amplify a current flowing through a resistance element (not shown) inserted in series in a closed loop circuit including the gate lines G1 to Gn and the source lines S1 to Sm, respectively.

  The gate line switch circuit 119 includes a plurality of switch elements such as field effect transistors (hereinafter also referred to as connection switch elements) formed on the other end portion of the gate line of the active matrix substrate constituting the liquid crystal panel 112. The control signal GDET for controlling opening / closing of the switch element is input to the gate of each switch element (transistor) 119a.

  Similarly, the source line switch circuit 1110 includes a plurality of switch elements (hereinafter referred to as connection switches) formed on the other end portion of the source line of the active matrix substrate constituting the liquid crystal panel 112, such as field effect transistors. It is also referred to as an element.) 1110a, and a control signal SDET for controlling opening / closing of the switch element is input to the gate of each switch element (transistor) 1110a.

  In FIG. 11, reference numeral 1114 denotes a position indicating pen that emits an electromagnetic wave from the tip to indicate a position on the liquid crystal panel. When the electromagnetic wave is thus emitted, an induced current is supplied to the first and second closed loop circuits. Is supposed to occur. Reference numeral 1113 denotes a coordinate detection circuit that detects a position (coordinates) on the liquid crystal panel instructed by the position pointing pen 1114. The coordinate detection circuit 1113 receives the first electromagnetic wave emitted from the position pointing pen 1114. The coordinates of the position pointing pen 1114 are detected based on the electromotive force waveform induced in the second closed loop circuit. The coordinate detection circuit 1113 receives the outputs Yk and Xk from the amplifier circuits 117 and 118, and calculates the coordinates of the position designated by the position pointing pen 1114 based on the outputs Yk and Xk. Yes.

  By the way, the coordinate detection apparatus 111 having such a configuration has a display period in which an image is displayed on the liquid crystal panel 112 in one frame period and a coordinate detection period in one frame period.

  During the display period in which image display is performed on the liquid crystal panel 112 in one frame period, the switch elements 119a and 1110a of the switch circuits 119 and 1110 are turned off, and the gate lines G1 to Gn and source lines S1 to S1 are turned off. A drive signal for display is supplied to Sm.

  In the coordinate detection period in one frame period, the switch elements 119a and 1110a of the switch circuits 119 and 1110 are turned on, and the gate line current detection circuit 115 and the source line current detection circuit 116 include the gate lines G1 to Gn. A second closed loop circuit including the first closed loop circuit and the source lines S1 to Sm is formed. Specifically, in the X signal detection period of the coordinate detection period, the first closed loop circuit including the gate lines G1 to Gn is sequentially formed as described above, and in the Y signal detection period of the coordinate detection period, the source lines S1 to S1 are formed. The second closed loop circuit including Sm is sequentially formed as described above.

  In this state, when the user positions the tip close to the liquid crystal panel 112 so that the user designates a certain part on the liquid crystal panel 112 with the position pointing pen 1114, the electromagnetic waves emitted from the position pointing pen 1114 A high-frequency induced current is generated in the first closed loop circuit of the gate lines G1 to Gn and the second closed loop circuit of the source lines S1 to Sm.

  The induced current is extracted outside the liquid crystal panel via the gate line current detection circuit 115 and the source line current detection circuit 116, amplified by the amplification circuits 117 and 118, and input to the coordinate detection circuit 1113. Here, the first closed loop circuit of the gate lines G1 to Gn is formed so as to move sequentially in the arrangement direction of the gate lines G1 to Gn during the Y signal detection period of the coordinate detection period, and the second closed loop of the source lines S1 to Sm. The circuit is formed to sequentially move in the Y direction during the X signal detection period of the coordinate detection period.

  As a result, the induced current induced in the first and second closed loop circuits at the individual positions of the liquid crystal panel is supplied to the coordinate detection circuit 1113, and the position indicating pen is started from the timing when the induced current reaches its peak. The Y coordinate and X coordinate of the position on the liquid crystal panel designated by 1114 are calculated.

JP-A-10-49301

  By the way, in the conventional display-integrated coordinate detection apparatus that uses such a gate line and a source line as a display drive line and a coordinate detection drive line, when the electromagnetic induction method is used for coordinate detection, coordinate detection is performed. In some cases, a closed loop circuit must be formed, so that normal display driving cannot be performed.

  For this reason, a display period and a coordinate detection period exist between one frame. Here, in the past, coordinate detection was performed using a display blanking period (see FIG. 1 described later), but in this case, the coordinate detection rate depends on the frame rate of the display panel. To be.

  For this reason, in a display panel with a low frame rate, output to the display panel is slow with respect to operations such as pen input, and the user feels stress. Even in a general display panel (frame rate 60 Hz), the coordinate detection rate may not satisfy the requirement when highly accurate pen input is required.

  Therefore, the present invention has been made in view of such a current situation, and an object of the present invention is to provide a coordinate detection apparatus capable of increasing the coordinate detection rate.

  According to the present invention, a matrix type display panel having pixels at intersections between gate lines and source lines arranged so as to be orthogonal to each other, and a plurality of the gate lines are sequentially selected to form a first closed loop circuit. A switching circuit; a second switching circuit that sequentially selects a plurality of the source lines to form a second closed loop circuit; and a position on the display panel, and an induced current in the first closed loop circuit and the second closed loop circuit A position indicator that emits an electromagnetic wave so as to generate, and coordinate detection means for detecting coordinates on the display panel indicated by the position indicator from induced electromotive forces generated in the first closed loop circuit and the second closed loop circuit A coordinate detection apparatus having an image rewriting period and a coordinate detection period, wherein the first and second closed loop circuits are sequentially operated in the coordinate detection period. Performs coordinate detection by the drive to the coordinate detecting means, wherein the image rewriting period is characterized in that rewriting only the pixels corresponding to the detected coordinates.

  As in the present invention, by performing coordinate detection by the coordinate detection means during the coordinate detection period and rewriting only the pixels corresponding to the detected coordinates during the image rewrite period, the image rewrite period is shortened, The rate of coordinate detection can be increased.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings.

  FIG. 2 is a conceptual diagram showing the configuration of the coordinate detection apparatus according to the first embodiment of the present invention. In FIG. 2, reference numeral 2 denotes an electromagnetic induction display panel integrated coordinate detection apparatus having a display panel 21. It is. Here, the display panel 21 is an electrophoretic display panel having an electrophoretic display element 22 (having a memory property) as a display element on an active matrix substrate, and a plurality of display panels 21 arranged orthogonal to each other. It has gate lines G1 to Gn and a plurality of source lines S1 to Sm.

  A TFT element 23 and an electrophoretic display element 22 are provided at the intersections of the gate lines G1 to Gn and the source lines S1 to Sm, and the gate line G1 is connected to the gate of each TFT element 23. To Gn, the source lines S1 to Sm are connected to the source of the TFT element 23, and the drive electrode of the electrophoretic display element 22 is connected to the drain.

  The coordinate detection apparatus 2 also includes a gate line driving circuit 24 that supplies driving signals corresponding to the scanning signals to the gate lines G1 to Gn, and a source that supplies driving signals corresponding to the display image information to the source lines S1 to Sm. The line drive circuit 25 is provided, and the gate line drive circuit 24 and the source line drive circuit 25 are driven at a desired timing, whereby an image is displayed on the display panel 21.

  Here, the gate line driving circuit 24 has a function of short-circuiting all the gate lines G1 to Gn by the G_ALL signal, as shown in FIG. 3 (general signal lines are omitted). In addition, the shorted gate lines G1 to Gn have a function of making the floating state by SWz. Similarly, the source line driving circuit 25 has a function of short-circuiting all the source lines S1 to Sm, and further has a function of bringing the shorted source lines S1 to Sm into a floating state.

  Further, as shown in FIG. 2, the coordinate detection apparatus 2 includes a first switching circuit 26 connected to the gate lines G1 to Gn at the opposite end of the gate line drive circuit 24, and a source line S1 at the opposite end of the source line drive circuit 25. To Sm, the second switching circuit 27 is provided.

  4 shows the first switching circuit 26. As shown in FIG. 4, the switches SWa1, SWa2,..., SWai are connected to the gate lines G1, G2,. The switches SWb1, SWb2,... SWbi are connected to the gate lines Gi + 1, Gi + 2,.

  In the coordinate detection period in one frame period, for example, among the plurality of switches SWa1 to SWbi, first, for example, SWa1 and SWb1 are turned on and connected to the output stage by the selection signal SEL. Then, the gate line G1 and the gate line Gi + 1 are selected by the first switching circuit 26 as described above, and all the gate lines G1 to Gn are short-circuited by the gate line driving circuit 24, whereby the gate line G1 and the gate line Gi + 1 are Is used to form a first closed loop circuit.

  Note that one end of the first closed loop circuit by the gate line G1 and the gate line Gi + 1 is connected to the current detection circuit 28 for the gate line loop, and the other end of the first closed loop circuit is at the constant voltage point Vg. Connected. Here, in the present embodiment, the voltage at the constant voltage point connected to the first closed loop circuit is the OFF voltage of the TFT element 23.

  On the other hand, for the source lines S1 to Sn, a closed loop circuit is similarly formed by switching of the second switching circuit 27, and one end of the second closed loop circuit by the source lines S1 to Sn is used for the source line loop shown in FIG. The other end is connected to a constant voltage point. Note that the voltage at a constant voltage point connected to the second closed loop circuit is 0V.

  In FIG. 2, reference numeral 210 denotes a position indicator for indicating a position on the display panel. The position indicator 210 is an electromagnetic wave from one end of the first and second closed loop circuits so that an induced current is generated. It is the structure which discharges. In the present embodiment, the position indicator 210 includes a resonance circuit including a coil and a capacitor so that the electromagnetic wave can be received and stored, and the electromagnetic wave can be transmitted using the charge.

  Reference numeral 30 denotes a coordinate detection circuit that is a coordinate detection means for detecting coordinates on the display panel instructed by the position indicator 210. When the position on the display panel is instructed by the position indicator 210, coordinate detection is performed. The device 2 rewrites the screen corresponding to the position on the display panel based on the coordinate information from the coordinate detection circuit 30.

  Further, as shown in FIG. 5, the electrophoretic display element 22 having a memory property is provided on a pair of substrates 50A and 50B and one substrate 50B, and a drive electrode 51 connected to the drain of the TFT element 23, A common electrode 52 that is driven in common for all pixels, a positively charged black charged electrophoretic particle 53, a dispersion liquid 54 that includes a medium and a plurality of charged electrophoretic particles 53, and an insulating reflective layer 55 are provided.

  When the common electrode 52 is grounded and a positive voltage (+ V1) is applied to the drive electrode 51, the black charged particles 53 gather near the common electrode 52 and the bottom reflective layer 55 is exposed, thereby displaying white. It becomes a state. On the other hand, when a negative voltage (−V1) is applied to the drive electrode 51, the black charged particles 53 gather near the drive electrode 51 and cover the reflective layer 55 on the bottom surface. Become. Note that the pixels once in the white state and the black state are maintained in the state even when 0 V is applied between the electrodes.

  In the present embodiment, the description will be made using a monochrome binary display panel in order to simplify the description. In addition, as the electrophoretic display element 22, a substrate provided with the drive electrode 51 on one substrate 50 </ b> B is used, but one using a substrate provided with a pair of electrodes on at least one of a pair of substrates, or a pair A substrate using an electrode provided on each substrate may be used.

  Next, the operation of the present embodiment will be described.

  The display panel 21 in the present embodiment has a mode in which no position instruction is given by the position indicator 210 (pen input OFF) and a mode in which a position instruction is given by the position indicator 210 (pen input ON). The time required to rewrite the image on the entire display panel is 100 msec (frame rate: 10 Hz).

  When the pen input is OFF, only the image rewriting period is provided as shown in FIG. 1A, and when the pen input is ON, coordinate detection is performed as shown in FIG. It has a period and an image rewriting period. Hereinafter, an operation when the pen input is turned on will be described, and a process of overwriting the pen input (coordinate detection result) on the still image will be described.

  First, the coordinate detection period for detecting the coordinate position will be described.

  In the coordinate detection period, as shown in FIG. 3, one end of all gate lines G1 to Gn is short-circuited by the gate line driving circuit 24 (G_ALL). At the same time, as shown in FIG. 4, in the first switching circuit 26, according to the selection signal SEL, SWa1 and SWb1 are first turned ON, the gate line G1 is connected to OUT1, and the gate line Gi + 1 is connected to OUT2. Thereby, the first first closed loop circuit is formed by the gate line G1 and the gate line Gi + 1. Similarly, at the next timing, the second first closed loop circuit is formed by the gate line G2 and the gate line Gi + 2. In this manner, a closed loop circuit is sequentially formed using the gate lines, and the entire display area is scanned.

  Here, when the first closed loop circuit is sequentially scanned in this way, an induced current is strongly induced in the closed loops Ln−1, Ln, Ln + 1 close to the position indicator 210 as shown in FIG. 6. This induced current is detected by a current detection circuit 28 connected to OUT1. When the first closed loop circuit is sequentially scanned such as the first first closed loop circuit, the second first closed loop circuit,..., The i th first closed loop circuit, as shown in FIG. In addition, the current value changes for each loop.

  The envelope shown in FIG. 7A is as shown in FIG. 7B. In FIG. 7B, the position indicator 210 indicates the coordinate with the largest output signal. It becomes coordinates. These outputs are input to the coordinate detection circuit 30 (see FIG. 2), and the coordinate detection circuit 30 can detect the Y coordinate indicated by the position indicator 210 from the above.

  As described above, the Y coordinate of the position indicator 210 is detected using the gate line. The X coordinate is also detected by driving the source line in the same manner. In this way, the coordinates (x, y) indicated by the position indicator 210 are detected.

  Next, an image rewriting period for rewriting an image will be described. The following image rewriting operation is controlled by a control device (not shown).

  Here, in the present embodiment, since the electrophoretic display element 22 having a memory property is used as the display element, in the step of overwriting the coordinate detection result on the still image, the image rewriting period is performed. Only the pixels to be overwritten are rewritten.

  In the image rewriting period, a short circuit of all gate lines by the gate line driving circuit 24 is first released by a control device (not shown). At the same time, all switches in the first switching circuit 26 are turned off. Similarly, the short circuit of all the source lines by the source line driving circuit 25 is released, and all the switches in the second switching circuit 27 are turned off at the same time.

  Next, the control device performs a rewrite operation on the pixel corresponding to the coordinate (x, y) detected by the coordinate detection circuit 30 in the previous coordinate detection period. In this case, the gate line drive circuit 24 selectively applies the TFT ON voltage Von to the gate line Gy corresponding to the coordinates (x, y), and the TFT elements 23 to the other gate lines G1 to Gn. OFF voltage Voff is applied.

  Then, the black write voltage V1 is selectively applied to the source line Gx corresponding to the coordinates (x, y) from the source line driving circuit 25, and 0 V is applied to the other source lines S1 to Sn. With the above operation, the pixel corresponding to the coordinates (x, y) is rewritten. Here, by rewriting only the pixels to be overwritten in this way, it is not necessary to scan all the gate lines in the image rewriting period.

  In this way, coordinates are detected in the coordinate detection period, and thereafter, in the image rewriting period, gate lines and source lines including pixels corresponding to the detected coordinates are selectively driven to rewrite only the pixels. Thus, as shown in FIG. 1B, the image rewriting period can be shortened and the coordinate detection rate can be increased as compared with the case without the coordinate detection period shown in FIG. Can do. As a result, a pen input operation without stress can be performed even with a display panel having a low frame rate. In addition, even a display panel with a high frame rate can perform a pen input operation with higher accuracy.

  Next, a second embodiment of the present invention will be described.

  FIG. 8 is a conceptual diagram showing a configuration of a coordinate detection apparatus according to the second embodiment of the present invention. In FIG. 8, reference numeral 9 denotes an electromagnetic induction display panel integrated coordinate detection apparatus having a display panel 91. It is. Here, the display panel 91 has a plurality of gate lines G1 to Gn and a plurality of source lines S1 to Sn arranged so as to be orthogonal to each other, like the display panel 91 of the first embodiment described above. ing.

  A TFT element 93 and an electrophoretic display element 92 are provided at intersections of the gate lines G1 to Gn and the source lines S1 to Sm, and the gate line G1 is connected to the gate of each TFT element 93. To Gn, the source lines S1 to Sm are connected to the source of the TFT element 93, and the drive electrode of the electrophoretic display element 92 is connected to the drain.

  The coordinate detection device 9 includes a gate line drive circuit 94 including a plurality of sub gate line drive circuits 94a, 94b,..., 94f that supply drive signals corresponding to scanning signals to the gate lines G1 to Gn. And a source line driving circuit 95 including a plurality of sub source line driving circuits 95a, 95b,..., 95f for supplying driving signals corresponding to the display image information to the source lines S1 to Sm.

  The sub gate line drive circuits 94a, 94b,..., 94f of the gate line drive circuit 94 and the sub source line drive circuits 95a, 95b,. Images are displayed on the display panel 21 by being selectively driven at a desired timing by the apparatus.

  It should be noted that the gate line driving circuit 94 and the source line driving circuit 95 in this embodiment also have a plurality of sub gate line driving circuits 94a, 94b,... 94f and sub source line driving circuits 95a, 95b. ,..., 95f, in other words, at least the gate line driving circuit 94 includes a plurality of sub-gate line driving circuits 94a, 94b,. Is possible.

  Here, in the present embodiment, the gate line driving circuit 94 is not cascade-connected unlike the general gate line driving circuit, as shown in FIG. 9, and the sub-gate line driving circuits 94a, 94b, .., 94f are wirings for receiving the START signal for starting the formation of the first closed loop circuit independently of each other. The gate line driving circuit 94 has a function of short-circuiting all the gate lines G1 to Gn by G_ALL1, 2 signals.

  On the other hand, the source line driving circuit 95 has a general connection. Note that the source line driver circuit 95 has a function of short-circuiting all the source lines S1 to Sm, similarly to the gate line driver circuit 94.

  The coordinate detection device 9 includes a first switching circuit 96 connected to the gate lines G1 to Gn at the opposite end of the gate line driving circuit 94, and a first switching circuit 96 connected to the source lines S1 to Sn at the opposite end of the source line driving circuit 95. 2 switching circuit 97 is provided.

  The internal structures of the first and second first switching circuits 96 and 97 are the same as those of the first and second switching circuits 26 and 27 shown in FIG. 4 of the first embodiment described above. Further, the current detection circuit 98 for the gate line loop and the current detection circuit 99 for the source line loop are also the current detection circuit 28 for the gate line loop and the source line loop shown in FIG. 2 of the first embodiment described above. This is the same as the current detection circuit 29 of FIG. Further, the coordinate detection device 9 includes a position indicator 910 having a power source for generating electromagnetic waves, unlike the position indicator 210 shown in FIG. 2 of the first embodiment described above.

  Next, the operation of the present embodiment will be described.

  First, the coordinate detection period for detecting the coordinate position will be described.

  In the coordinate detection period, a control device (not shown) drives one end of the gate lines G1 to G2k by the gate line drive circuits 94a and 94b (G_ALL1, 2) shown in FIG. 9 and another gate line drive shown in FIG. One end of the other gate lines G2k + 1 to Gn is short-circuited by the circuit. At the same time, similarly to FIG. 4 described above, in the first switching circuit 96, SWa1 and SWb1 are first turned ON, the gate line G1 is connected to OUT1, and the gate line Gi + 1 is connected to OUT2. As a result, the first first closed loop circuit is formed by the gate line G1 and the gate line Gi + 1.

  Similarly, at the next timing, the second first closed loop circuit is formed by the gate line G2 and the gate line Gi + 2. In this way, a closed loop circuit is sequentially formed using the gate lines G1 to Gn, and the entire display area is scanned.

  Thereafter, as in the first embodiment described above, the induced current generated in the first closed loop circuit that sequentially scans is measured, and based on the measurement result, detection of the Y coordinate indicated by the position indicator 910 is performed. Is performed by the coordinate detection circuit 30. Further, the same driving is performed for the source lines S1 to Sn, and the coordinate detection circuit 30 detects the X coordinate indicated by the position indicator 910, and the coordinates (x, y) indicated by the position indicator 910 are detected. To detect.

  Next, an image rewriting period for rewriting an image will be described.

  In the image rewriting period, first, the short circuit of all the gate lines G1 to Gn by the gate line driving circuit 94 is released. At the same time, in the first switching circuit 96, all the switches are turned off. Similarly, the short circuit of all the source lines S1 to Sn by the source line drive circuit 95 is released, and all the switches in the second switching circuit 97 are turned off at the same time.

  Next, the first closed loop circuit including the pixel corresponding to the coordinates (x, y) detected in the previous coordinate detection period is selected from the gate line driving circuit 94. Here, the detected coordinates (x, y) are pixels included in the gate line corresponding to the gate line G2 driven by the sub-gate line drive circuit 94a and the source line S2 driven by the sub-source line drive circuit 95a.

  Next, the signal line of START1 for starting image rewriting of the sub-gate line driving circuit 94a is activated, and scanning of the gate lines G1 to Gk of the sub-gate line driving circuit 94a is started. When scanning of the gate lines G1 to Gk is started in this way, first, Von is applied to the gate line G1 from the sub-gate line driving circuit 94a in synchronization with the horizontal synchronization signal HSYNC, and the other gate lines G2 Voff is applied to .about.Gk. In synchronization with this, the source line drive circuit 95 applies 0 V to all the source lines S1 to Sn. In this case, the image is not rewritten.

  Next, in synchronization with the horizontal synchronization signal HSYNC, Von is applied from the sub-gate line drive circuit 94a to the gate line G2 corresponding to the Y coordinate of the detected coordinates (x, y), and the other gate lines G1, G3. Voff is applied to ~ Gk. In synchronization with this, the black writing voltage V1 is applied to the source line S2 corresponding to the X coordinate of the detected coordinates (x, y), and 0 V is applied to the other source lines S1, S3 to Sn. To do. Then, when such a writing voltage V1 is applied, the image is rewritten with respect to the pixel corresponding to the detected coordinate (x, y).

  Even after such image rewriting is performed, the sub-gate line driving circuit 94a sequentially scans up to the gate line Gk and applies 0 V to all the source lines in synchronization therewith. Then, the scanning of all the gate lines G1 to Gk that can be driven by the sub-gate line driving circuit 94a is performed in this way, and the image rewriting period ends when the scanning is completed. During this period, Voff is output to the gate lines from the other sub-gate line driving circuits 94b,.

  Here, as in the present embodiment, the gate line driving circuit 94 includes a plurality of sub-gate line driving circuits 94a, 94b,..., 94f, and includes pixels corresponding to the detected coordinates in the image rewriting period. By scanning only the predetermined sub-gate line driving circuit 94a that drives the gate line G2, in other words, the coordinates are detected in the coordinate detection period, and only the predetermined sub-gate line driving circuit 94a is scanned in the image rewriting period. By doing so, as shown in FIG. 1 described above, the image rewriting period can be shortened, and the coordinate detection rate can be increased.

  Next, a third embodiment of the present invention will be described.

  In this embodiment, coordinate detection is performed using a gate line or source line that is not involved in image rewriting, and the coordinate detection rate is increased.

  FIG. 10 shows the internal structure of the gate line drive circuit of the coordinate detection apparatus according to the present embodiment. The gate line drive circuit 44 of the present embodiment selects an arbitrary gate line and selects Von. Can be output, and all other gate lines can be short-circuited. Further, the shorted gate line has a switch SWz for outputting a floating state without outputting Von or Voff. Although not shown, the source line driver circuit according to this embodiment has a similar circuit configuration.

  Next, the operation of the present embodiment will be described.

  First, as in the second embodiment described above, when the coordinates (x, y) are detected by the previous coordinate detection, and the corresponding gate line and source line are the gate line Gx and the source line Sy, the coordinates are the same. In order to rewrite the pixel corresponding to (x, y), the gate line Gx is selected as a predetermined gate line in the gate line driving circuit 44, and the ON voltage Von of the TFT element is applied to the gate line Gx as a rewrite signal. . In a source line drive circuit (not shown), a source line Sy is selected as a predetermined source line, and a write voltage V1 is applied to the source line Sy as an information signal.

  During the writing, all the gate lines other than Gx are short-circuited in the gate line driving circuit 44 and are in a floating state, and all the sources other than Sy are also in the source line driving circuit. The line is floating.

  By the way, in this embodiment, coordinate detection is performed simultaneously with such a writing operation. Here, the principle of coordinate detection is the same as that of the first embodiment, but in this embodiment, all other gate lines other than the gate line Gx selected for writing are used for the first. A closed loop circuit is formed and scanned. Further, the second closed loop circuit is formed and scanned using all the source lines other than the source line Sy selected for writing.

  Then, while the image is rewritten in this way, the coordinate detection rate can be increased by performing the coordinate detection using the gate line or the source line not involved in the image rewriting.

  In the present embodiment, the coordinate detection is not limited to scanning all closed loop circuits. Preferably, coordinate detection is performed by scanning N closed loop circuits [1 <N <(number of closed loop circuits that can be formed by gate lines or source lines)] close to the coordinates previously specified by the position indicator. Like that. As a result, the number of closed loop circuits to be scanned can be reduced, and the coordinate detection rate can be increased.

  By the way, in the description so far, a display panel having a memory property is used, but the display panel to be used is not limited to a display panel having a memory property, and a liquid crystal panel / organic EL panel can also be used. When a display panel having a memory property is used, it is not always necessary to rewrite the image. That is, in some cases, an image rewriting period may not be required, and in that case, only a coordinate detection period is required. When such a display panel is used, the coordinate detection rate can be further increased as compared with the case where one frame has both the image rewriting period and the coordinate detection period.

  In the description so far, the case where a power indicator is used as the position indicator has been described, but the present invention is not limited to this. Preferably, the position indicator has a charging mechanism, transmits the electromagnetic wave using a closed loop formed by the gate line and the source line, charges the position indicator, and transmits the electromagnetic wave from the position indicator using the energy. Coordinate detection may be performed.

  Further, in the description so far, an electrophoretic display element has been used as a display element having a memory property. However, the present invention is not limited to this, and a display medium such as a polymer network liquid crystal or a ferroelectric liquid crystal is used. The present invention can also be applied to a display device using liquid crystal. Furthermore, the electrophoretic display element can be applied to both a vertically moving electrophoretic display element and a horizontal moving electrophoretic display element. Further, the present invention can also be applied to a configuration in which a dispersion liquid 54 including the liquid shown in FIG. 5 and a plurality of charged electrophoretic particles 53 is included in each of a large number of microcapsules.

The time chart figure which shows the image rewriting period and coordinate detection period of the coordinate detection apparatus which concerns on the 1st Embodiment of this invention. The conceptual diagram which shows the structure of the said coordinate detection apparatus. The figure which shows the detailed state of the gate line drive circuit in the said coordinate detection apparatus. The figure which shows the detailed state of the 1st switching circuit in the said coordinate detection apparatus. The schematic diagram which shows the pixel cross section of the electrophoretic display element in the said coordinate detection apparatus. The figure which shows the positional relationship of the position of the position indicator in the said coordinate detection apparatus, and the closed loop circuit formed in the periphery. In the coordinate detection apparatus, (a) is a diagram showing the relationship between the position of the position indicator and the output signal from the closed loop circuit formed around it, and (b) is a smooth change in the output signal shown in (a). The figure converted into an envelope and shown. The conceptual diagram of the position indicator of the coordinate detection apparatus which concerns on the 2nd Embodiment of this invention. The conceptual diagram which shows the structure of the said coordinate detection apparatus. The figure which shows the internal structure of the gate line drive circuit of the coordinate detection apparatus which concerns on the 3rd Embodiment of this invention. The conceptual diagram of the conventional coordinate detection apparatus.

Explanation of symbols

2,9 Coordinate detection device 21, 91 Display panel 22, 92 Electrophoretic display element 23, 93 TFT element 24 Gate line drive circuit 25 Source line drive circuit 26, 96 First switching circuit 27, 97 Second switching circuit 28, 98 Current detection circuit 29, 99 Current detection circuit 30 Coordinate detection circuit 44 Gate line drive circuit 94 Gate line drive circuits 94a, 94b,..., 94f Sub-gate line drive circuit 95 Source line drive circuits 95a, 95b,. Sub-source line drive circuit 210 Position indicator 910 Position indicators G1 to Gn Gate lines S1 to Sm Source lines

Claims (10)

A matrix type display panel having pixels at intersections between gate lines and source lines arranged orthogonal to each other; a first switching circuit that forms a first closed loop circuit by sequentially selecting a plurality of the gate lines; A second switching circuit that sequentially selects a plurality of the source lines to form a second closed loop circuit, indicates a position on the display panel, and an induced current is generated in the first closed loop circuit and the second closed loop circuit. Coordinates comprising: a position indicator that emits electromagnetic waves; and coordinate detection means that detects coordinates on the display panel indicated by the position indicator from the induced electromotive force generated in the first closed loop circuit and the second closed loop circuit. In the detection device,
It has an image rewriting period and a coordinate detection period,
During the coordinate detection period, the first and second closed loop circuits are sequentially driven to perform coordinate detection by the coordinate detection means, and during the image rewriting period, only the pixels corresponding to the detected coordinates are rewritten. A coordinate detection apparatus characterized by performing.   The coordinate detection apparatus according to claim 1, wherein the display panel is a display panel having a memory property.   The display panel having a memory property includes a pair of electrodes provided on at least one substrate, or a pair of substrates provided with electrodes on each substrate, and is disposed between the pair of substrates. The coordinate detection apparatus according to claim 2, further comprising a medium in which the charged electrophoretic particles are dispersed. A gate line driving circuit for driving the gate line during the image rewriting period;
A source line driving circuit for driving the source line during the image rewriting period;
With
2. The gate line and source line including pixels corresponding to the detected coordinates are selectively driven by the gate line driving circuit and the source line driving circuit during the image rewriting period. Coordinate detection device.   5. The coordinate detection apparatus according to claim 4, wherein at least the gate line drive circuit of the gate line drive circuit and the source line drive circuit has a function of driving a selected gate line.   At least the gate line driving circuit of the gate line driving circuit and the source line driving circuit is configured by a plurality of sub-gate line driving circuits, and a gate line including the pixels corresponding to the detected coordinates 5. The coordinate detection apparatus according to claim 4, wherein the coordinate detection apparatus is driven by a predetermined sub gate line driving circuit of the sub gate line driving circuits.   The coordinate detection apparatus according to claim 1, wherein when the coordinate detection is not performed, pixel rewriting is not performed during the image rewriting period. The gate line driving circuit and the source line driving circuit each have a function of short-circuiting a gate line other than the predetermined gate line and a source line other than the predetermined source line,
For the pixel to be rewritten, the predetermined gate line is selected by the gate line driving circuit and a rewrite signal is output, and an information signal is output to the predetermined source line and the pixel is rewritten and selected. 5. The coordinate detection apparatus according to claim 4, wherein coordinate detection is performed using a gate line other than the predetermined gate line and a source line other than the predetermined source line.   The coordinate detection apparatus according to claim 1, wherein the position indicator includes a power source for generating electromagnetic waves therein. An electromagnetic wave transmission circuit for applying and driving an alternating voltage of a predetermined frequency to the first closed loop circuit and the second closed loop circuit so as to transmit an electromagnetic wave to the position indicator is provided, and the position indicator receives the electromagnetic wave. The coordinate detection apparatus according to claim 1, wherein the coordinate detection apparatus is configured to store electric charges and transmit electromagnetic waves using the electric charges.

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