JP2006163745A - Coordinate detection apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coordinate detection apparatus capable of accurate coordinate detection. <P>SOLUTION: A loop circuit for detection of a first position, for detecting coordinates on a display panel 11 indicated by a position indicator 110, is formed using a first and a second group of gate wires, each of which consists of at least two or more sequentially selected gate wires. The first group of gate wires is connected to an electromotive force detection circuit 18 and the second group of gate wires is connected to a certain constant voltage point. A loop circuit for detection of a second circuit is formed using a first and a second group of source wires, each of which consists of at least two or more sequentially selected source wires. The first group of source wires is connected to an electromotive force detection circuit 19 and the second group of source wires is connected to a certain constant voltage point. <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. 7 is a diagram for explaining the configuration of such a conventional coordinate detection apparatus. In FIG. 7, 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 a 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. First closed loop forming means for sequentially forming 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 are provided as source lines S1 to S1. 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. 7, 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 the 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 lines G1 to Gn are included by the gate line current detection circuit 115 and the source line current detection circuit 116. 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 coordinate detecting device having such a configuration, when forming a closed loop circuit, only two gate lines and two source lines are used. Therefore, the gate lines and the source lines have sufficiently low resistance. If it is not formed with a simple conductor, highly accurate coordinate detection cannot be performed.

  Therefore, in order to perform coordinate detection with high accuracy, it is necessary to increase the electromagnetic wave output of the position pointing pen 1114. However, when the electromagnetic wave output is increased in this way, the position pointing pen 1114 increases in size and is consumed. There was a problem that electric power would become large.

  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 performing highly accurate coordinate detection.

  The present invention relates to a matrix type display panel having pixels at intersections between gate lines and source lines arranged orthogonal to each other, and a first position detection loop formed by sequentially selecting a plurality of the gate lines. A circuit, a second position detection loop circuit formed by sequentially selecting a plurality of source lines, a position on the display panel, and a first position detection loop circuit and a second position detection A position indicator that emits electromagnetic waves so that an induced current is generated in the loop circuit, an electromotive force detection circuit that detects the magnitude of the electromotive force generated in the first and second position detection loop circuits, and the electromotive force detection circuit Coordinate detection means for detecting coordinates on the display panel instructed by the position indicator on the basis of a signal from each of the first position detection loop circuits. The gate lines are sequentially formed by a first gate line group and a second gate line group composed of the sequentially selected gate lines, the first gate line group is used as the electromotive force detection circuit, and the second gate line group is formed as an arbitrary constant. The second position detection loop circuit connected to each voltage point is sequentially formed by a first source line group and a second source line group each including at least two or more source lines that are sequentially selected, and The first source line group is connected to the electromotive force detection circuit, and the second source line group is connected to an arbitrary constant voltage point.

  As in the present invention, a first gate line group comprising gate lines sequentially selected from at least two first position detection loop circuits for detecting coordinates on a display panel instructed by a position indicator. And the second gate line group are sequentially formed, and the second position detection loop circuit is sequentially formed by the first source line group and the second source line group each including at least two source lines sequentially selected. As a result, the wiring resistance can be reduced. As a result, a sufficient current due to electromagnetic induction generated in the first and second position detection loop circuits can be obtained, and highly accurate coordinate detection can be performed.

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

  FIG. 1 is a conceptual diagram showing a configuration of a coordinate detection device according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes an electromagnetic induction type display panel integrated coordinate detection device having a display panel 11. Here, the display panel 11 is an electrophoretic display panel having an electrophoretic display element 12 (having a memory property) as a display element on an active matrix substrate, and a plurality of display panels 11 arranged orthogonal to each other. It has gate lines G1 to Gn and a plurality of source lines S1 to Sm.

  A TFT element 13 and an electrophoretic display element 12 are provided at intersections of these gate lines G1 to Gn and source lines S1 to Sm, and the gate line G1 is connected to the gate of each TFT element 13. To Gn, the source lines S1 to Sm are connected to the source of the TFT element 13, and the drive electrode of the electrophoretic display element 12 is connected to the drain.

  In addition, the coordinate detection apparatus 1 includes a gate line driving circuit 14 that supplies a driving signal corresponding to the scanning signal to the gate lines G1 to Gn, and a source that supplies a driving signal corresponding to the display image information to the source lines S1 to Sm. A line driving circuit 15 is provided, and the gate line driving circuit 14 and the source line driving circuit 15 are driven at a desired timing, whereby an image is displayed on the display panel 11.

  Here, the gate line driving circuit 14 is an analog switch type IC, and as shown in FIG. 2 (general signal lines are omitted), the function of selecting the gate lines G1 to Gn for supplying voltage, and the short circuit. The gate line G1 to Gn to be selected is supplied, and a control signal LogicC is input to the switch SWc via a bus, and voltage is supplied by switching each switching element connected to the gate lines G1 to Gn. The gate lines G1 to Gn that are short-circuited with the gate lines G1 to Gn can be arbitrarily selected.

  In addition, the short-circuited gate lines G1 to Gn are disconnected from the power supply line and have a switch SWd for floating. When all the gate lines G1 to Gn are short-circuited by the gate line driving circuit 14, all the short-circuited gate lines G1 to Gn are set in a floating state in the gate line driving circuit 14 by turning on the switch SWd. Become. Therefore, the first position detection loop circuit can be configured by using the gate lines G1 to Gn without affecting the power supply voltage of the gate line driving circuit 14.

  In order to place the shorted gate lines G1 to Gn in a floating state, a general-purpose gate is provided by installing a switch SWc for disconnecting the gate lines G1 to Gn from the power supply line outside the gate line driving circuit 14. All the gate lines can be short-circuited using the line drive circuit, and the short-circuited gate lines can be brought into a floating state in the gate line drive circuit.

  Similarly, the source line drive circuit 15 also has a function of arbitrarily selecting source lines S1 to Sm for supplying voltage and source lines S1 to Sm to be short-circuited. , And has a function of making a floating state by a switch (not shown) installed outside the source line driver circuit 15.

  Further, as shown in FIG. 1, the coordinate detection apparatus 1 includes a first switching circuit 16 connected to the gate lines G1 to Gn at the opposite end of the gate line driving circuit 14 and a source line at the opposite end of the source line driving circuit 15. A second switching circuit 17 connected to S1 to Sm is provided.

  FIG. 3 is a diagram showing the first switching circuit 16, and as shown in FIG. 3, the first switching circuit 16 includes switches SWa and SWb. Here, the switch SWa is connected to the gate lines G1 to Gn, and the control signal LogicA is input to the switch SWa, and the respective switching elements connected to the gate lines G1 to Gn are switched, thereby switching the first position. A plurality of arbitrary gate lines G1 to Gn forming a detection loop circuit can be selected.

  The switch SWb includes one input unit and two output units. The input unit is connected to the gate lines G1 to Gn selected by the switch SWa, and the output unit is connected to the current detection circuit 18 and the ground. ing. Here, the control signal LogicB is input to such a switch SWb, and it is selected whether the gate line selected by the switch SWa is connected to the current detection circuit 18 or to the ground. The gate line driving circuit 14 and the first switching circuit 16 can form a first position detection loop circuit.

  By the way, in the present embodiment, the first position detection loop circuit is formed by the first gate line group and the second gate line group each including at least two gate lines sequentially selected, and the first gate. The second gate line is connected to the ground, which is an arbitrary constant voltage point, to the current detection circuit 18 which is an electromotive force detection circuit for detecting the magnitude of the electromotive force generated in the first position detection loop circuit. I am doing so.

  For example, when the first position detection loop circuit is formed, the gate lines G1 to Gn are short-circuited by the switch SWc of the gate line driving circuit 14 and the gate line short-circuited by the switch SWd is set in a floating state, and at the same time, the first switching is performed. Two arbitrary gate lines are selected by the switch SWa of the circuit 16 to form the first gate line group and the second gate line group, and the first gate formed by one of the two gate lines by the switch SWb. The line group is connected to the current detection circuit 16 for detecting the magnitude of the electromotive force generated in the second position detection loop circuit, and the second gate line group formed by the other two gate lines is connected to the ground. To do. Even when three or more gate lines are used, the first position detection loop circuit can be created by the same method as described above.

  Here, the first position detection loop circuit is formed by the first and second gate line groups formed by bundling two or more gate lines by the first switching circuit 16 and the gate line driving circuit 14 in this way. As a result, the wiring resistance of the first position detection loop circuit can be reduced. As a result, a sufficient current due to electromagnetic induction generated in the first position detection loop circuit can be obtained, and coordinate detection with high accuracy becomes possible.

  In the present embodiment, the second position detection loop circuit is similarly formed by a first source line group and a second source line group each including at least two source lines that are sequentially selected. The source line group is connected to the current detection circuit 19 and the second source line is connected to the ground.

  Then, the second position detection loop circuit is formed by the first and second source line groups formed by bundling two or more source lines by the second switching circuit 17 and the source line driving circuit 15 in this way. Thus, the wiring resistance of the second position detection loop circuit can be reduced. As a result, a sufficient current due to electromagnetic induction generated in the second position detection loop circuit can be obtained, and coordinate detection with high accuracy is possible.

  In FIG. 1, reference numeral 110 denotes a position indicator that indicates a position on the display panel. The position indicator 110 has at least a coil and a tuning circuit, and includes first and second position detection loop circuits. Includes a radio wave generating means for generating a radio wave that can be tuned to the tuning circuit, and emits an electromagnetic wave (alternating current signal) having a predetermined frequency from one end thereof so that an induced current is generated in the first and second detection loop circuits. It has a configuration.

  Reference numeral 30 denotes a coordinate detection circuit which is a coordinate detection means for detecting coordinates on the display panel instructed by the position indicator 110. When the position on the display panel is instructed by the position indicator 110, coordinate detection is performed. The apparatus 1 rewrites the screen corresponding to the position on the display panel based on the coordinate information from the coordinate detection circuit 30.

  In addition, as shown in FIG. 4, the electrophoretic display element 12 having a memory property is provided on a pair of substrates 50A and 50B, one substrate 50B, and a drive electrode 51 connected to the drain of the TFT element 13, 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 12, one having the drive electrode 51 provided on one substrate 50B is used, but one using a substrate provided with a pair of electrodes on at least one of the 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 11 according to the present embodiment has a mode in which position indication by the position indicator 110 is not performed (pen input OFF) and a mode in which position indication is performed by the position indicator 110 (pen input ON). The time required to rewrite the image on the entire display panel is 100 msec (frame rate: 10 Hz).

  Further, when the pen input is OFF, only the image rewriting period is provided as shown in FIG. 5A, and when the pen input is ON, coordinate detection is performed as shown in FIG. 5B. It has a period and an image rewriting period.

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

  In the coordinate detection period, as shown in FIG. 2, one end of all the gate lines is short-circuited by the switch SWc of the gate line driving circuit 14, and the switch SWd is brought into a floating state. At the same time, the four gate lines G1, G2, G5, G6 are selected by the switch SWa of the first switching circuit 16 shown in FIG. 3, and the first gate line group is formed by the switch SWb. The gate lines G1 and G2 are connected to the current detection circuit 18, and the gate lines G5 and G6 which are two gate lines constituting the second gate line group are connected to the ground.

  As a result, a first position detection loop circuit using the four gate lines G1, G2, G5, and G6 is formed, and the four gate lines G1, G2, G5, and G6 are bundled in this manner to form the first. By forming the position detection loop circuit, the wiring resistance of the first position detection loop circuit can be reduced, and a sufficient current due to electromagnetic induction generated in the first position detection loop circuit can be obtained.

  Then, at the next timing, the next first position detection loop circuit is similarly formed using the gate lines G2, G3, G6, and G7. Thereafter, the first position detection loop circuit is sequentially formed in the scanning direction using the four gate lines as described above, and the entire display area is scanned.

  Here, regardless of the number of gate lines constituting the first position detection loop circuit, the gate line driving circuit 14 can arbitrarily set the scanning interval of the first position detection loop circuit with the gate line installation interval as a minimum unit. It is possible to switch so that the interval becomes.

  Thereby, for example, if the scanning interval of the first position detection loop circuit is performed in units of one gate line, the position detection loop circuit can scan with the same resolution as the pitch of the gate lines. A decrease in position detection accuracy can be prevented while lowering the wiring resistance of the loop circuit.

  Similarly, the second position detection loop circuit can be formed by bundling four source lines, and thereafter, the second position detection loop circuit is sequentially scanned using the four source lines. The entire display area can be scanned by forming in the direction in which the image is formed.

  Here, similarly to the gate line driving circuit 14, the source line driving circuit 15 has a scanning interval of the second position detecting loop circuit of the gate line regardless of the number of source lines forming the second position detecting loop circuit. It is possible to switch to an arbitrary interval with the installation interval as the minimum unit. Thus, it is possible to prevent the position detection accuracy from being lowered while lowering the wiring resistance of the position detection loop circuit.

  Next, the position detection principle of the position indicator 110 will be described with reference to FIG.

  First, four gate lines are sequentially selected, and as shown in FIG. 6A, the first position detection loop circuit 1, the first position detection loop circuit 2, and the first position detection loop circuit 3 are called. Scan sequentially. Here, when the position indicator 110 is brought close to the coordinate detection device 1, a large amount of induced electromotive current flows in the first position detection loop circuit 2 closest to the position indicator 110 as shown in FIG. This current is detected by a current detection circuit 18 (see FIG. 3) connected to the first position detection loop circuit.

  Next, this detection output is input to the coordinate detection circuit 30 (see FIG. 1), and the coordinate detection circuit 30 uses the current value detected by the current detection circuit 18 as a second order as shown in FIG. The position coordinate Xp of the position indicator 110 can be detected by approximating with a curve and obtaining the vertex of the approximate curve. As described above, the Y coordinate of the position indicator 110 can be detected using the gate line. The X coordinate is similarly detected using the source line. In this way, the coordinates (x, y) of the position indicator 110 are detected.

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

  In the present embodiment, since the electrophoretic display element 12 having a memory property is used, in the step of overwriting the coordinate detection result on the still image, only the pixel to be overwritten is rewritten during the image rewriting period. Just do it. First, in the image rewriting period, the short circuit of all the gate lines is released by the switch SWc of the gate line driving circuit 14. At the same time, in the first switching circuit 16, all the switches SWa are not connected to the gate lines. Similarly, the short circuit of all the source lines by the source line driving circuit 15 is released, and all the source lines are opened in the second switching circuit 17 at the same time.

  Next, a rewrite operation is performed on the pixel corresponding to the coordinates (x, y) detected in the previous coordinate detection period. The gate line driving circuit 14 applies the TFT on voltage Von to the gate line Gn corresponding to the coordinates (x, y), and the TFT off voltage Voff is applied to the other gate lines. Then, the black writing voltage V1 is applied to the source line Sm corresponding to the coordinates (x, y) from the source line driving circuit 15, and 0 V is applied to the other source lines. With the above operation, the pixel corresponding to the coordinate (x, y) is rewritten.

  As described above, in the present embodiment, the first position detection loop circuit is sequentially formed by the first gate line group and the second gate line group each including at least two gate lines sequentially selected, and the second By sequentially forming the position detection loop circuit by the first source line group and the second source line group each including at least two source lines sequentially selected, the wiring resistance can be reduced. As a result, a sufficient current due to electromagnetic induction generated in the first and second position detection loop circuits can be obtained, and highly accurate coordinate detection can be performed.

  In the above description, the case where all of the gate lines G1 to Gn and the source lines S1 to Sm are connected to the first and second switch circuits 16 and 17 has been described. However, the present invention is not limited to this. Instead of connecting all of the gate lines G1 to Gn and the source lines S1 to Sm to the first and second switch circuits 16 and 17, a part of the gate lines G1 to Gn and the source lines S1 to Sm, for example, all 1/24 of the number may be selected at equal intervals and connected to the first and second switch circuits 16 and 17.

  This time, a TFT was fabricated with a gate line pitch of 150 [μm] and a source line pitch of 50 [μm]. Although the scanning interval of the position detection loop circuit is 24 times the pitch of the gate line and the source line, it is possible to obtain position detection accuracy that does not give a sense of incongruity to pen input. As a result, the number of switching elements can be significantly reduced, and the display-integrated coordinate detection apparatus can be reduced in size and cost.

  In the above description, a display panel with a memory property is used. However, a display panel to be used is not limited to a display panel with a memory property, and a liquid crystal panel or an organic EL panel having no memory property is also used. Can do.

  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. Moreover, the present invention can also be applied to a configuration in which a dispersion liquid 54 including the liquid shown in FIG. 4 and a plurality of charged electrophoretic particles 53 is included in each of a large number of microcapsules.

The conceptual diagram which shows the structure of the coordinate detection apparatus which concerns on embodiment of this invention. The figure which shows the structure of the gate line drive circuit of the said coordinate detection apparatus. The figure which shows the structure of the 1st switching circuit of 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 time chart figure which shows the image rewriting period and coordinate detection period of the said coordinate detection apparatus. The figure explaining the position detection principle of the position indicator in the said coordinate detection apparatus. The conceptual diagram of the conventional coordinate detection apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Coordinate detection apparatus 11 Display panel 12 Electrophoretic display element 13 TFT element 14 Gate line drive circuit 15 Source line drive circuit 16 1st switching circuit 17 2nd switching circuit 18 Current detection circuit 19 Current detection circuit 30 Coordinate detection circuit 110 Position Indicators G1 to Gn Gate lines S1 to Sm Source lines

Claims (9)

A matrix type display panel having pixels at intersections between gate lines and source lines arranged orthogonal to each other;
A first position detection loop circuit formed by sequentially selecting a plurality of the gate lines;
A second position detection loop circuit formed by sequentially selecting a plurality of the source lines;
A position indicator for instructing a position on the display panel and emitting an electromagnetic wave so that an induced current is generated in the first position detection loop circuit and the second position detection loop circuit;
An electromotive force detection circuit for detecting the magnitude of the electromotive force generated in the first and second position detection loop circuits;
Coordinate detection means for detecting coordinates on the display panel instructed by the position indicator based on a signal from the electromotive force detection circuit;
With
The first position detection loop circuit is sequentially formed by a first gate line group and a second gate line group each including at least two gate lines that are sequentially selected, and the first gate line group is A first source comprising a power detection circuit, the second gate line group being connected to an arbitrary constant voltage point, and at least two second position detection loop circuits sequentially selected from the source lines. A line group and a second source line group are sequentially formed, and the first source line group is connected to the electromotive force detection circuit, and the second source line group is connected to an arbitrary constant voltage point. A coordinate detection device. A first switching circuit that connects the first gate line group to the electromotive force detection circuit and the second gate line group to an arbitrary constant voltage point;
A second switching circuit for connecting the first source line group to the electromotive force detection circuit and the second source line group to an arbitrary constant voltage point;
A gate line driving circuit for driving the gate line, the gate line being connected in parallel with the first switching circuit;
A source line driving circuit for driving the source line, the source line being connected in parallel with the second switching circuit;
With
The first position detection loop circuit is sequentially formed by the first switching circuit and the gate line driving circuit, and the second position detection loop circuit is formed by the source line driving circuit and the second switching circuit. The coordinate detection device according to claim 1, wherein the coordinate detection device is sequentially formed.   The gate line constituting the first gate line group and the second gate line group is sequentially selected in the scanning direction by the gate line driving circuit, and the first source line group and the second source line are selected by the source line driving circuit. 3. The coordinate detection apparatus according to claim 2, wherein selection is made sequentially in the scanning direction of the source lines constituting the group.   Regardless of the number of the gate lines forming the first position detection loop circuit, the scanning interval of the first position detection loop circuit is set to an arbitrary interval with the installation interval of the gate lines as a minimum unit. Regardless of the number of the source lines forming the second position detection loop circuit, the scanning interval of the second position detection loop circuit is an arbitrary interval with the installation interval of the source lines as a minimum unit. The coordinate detection apparatus according to claim 3.   The first switching circuit has a function of selecting and short-circuiting all gate lines, the second switching circuit has a function of selecting and short-circuiting all source lines, and the gate line driving circuit has all gate lines. 3. The coordinate detection apparatus according to claim 2, wherein the source line driving circuit has a function of short-circuiting all source lines.   The coordinate detection apparatus according to claim 1, wherein the position indicator includes at least a coil and a power source, and emits an AC signal having a predetermined frequency from one end.   The position indicator has at least a coil and a tuning circuit, and the first and second position detection loop circuits are provided with radio wave generating means for generating radio waves that can be tuned to the tuning circuit. The coordinate detection apparatus according to claim 1, wherein an alternating current signal is emitted.   The display panel includes a TFT element including three electrodes of a source electrode, a drain electrode, and a gate electrode for each pixel, and a common electrode that is arranged through the electric capacity with the drain electrode and is commonly driven in all the pixels. The coordinate detection device according to claim 1, further comprising a display element between the drain electrode and the common electrode. The display panel includes a pair of electrodes provided on at least one substrate, or a pair of substrates provided with an electrode on each substrate, and is disposed between the pair of substrates. The coordinate detection apparatus according to claim 8, further comprising a dispersed medium.

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