JPH06168066A - Display incorprated type tablet device - Google Patents

Abstract

PURPOSE:To easily view a display screen, to easily set a device to be compact and to easily reduce cost. CONSTITUTION:A switching circuit 7 changes over and selects a detection control circuit 6-side in a coordinate detection period in accordance with the control of a control circuit 10. A high frequency power source 12 impresses high frequency voltage on the tip electrode of an electronic pen 11. A segment driving circuit 3 sequentially scans the segment electrode X of a liquid crystal panel 1. Then, a common driving circuit 2 sequentially scans a common electrode Y. An x-coordinate detection circuit 8 and a y-coordinate detection circuit 9 detect the x-coordinate and the y-coordinate of the tip of the electronic pen 11 based on induced voltage induced by the segment electrode X and the common electrode Y. In a display period, a display control circuit 4-side is switched and selected, and a picture is displayed in the liquid crystal panel 1. Thus, the tablet device incorporating a display function is constituted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display-integrated tablet device integrated with a display function used in personal computers, word processors and the like.

[0002]

2. Description of the Related Art Conventionally, there is a display unit-integrated type tablet device in which a display unit and a tablet are laminated and integrally configured. FIG. 23 shows a schematic structure of an electrostatic induction tablet used in this display unit-integrated tablet device and its drive unit.
(For example, JP-A-60-171521).

The electrostatic induction tablet 101 includes a column electrode X ₁ ,
X _{2, ...,} X _m (hereinafter, an arbitrary column electrode referred to as X) glass substrate are arranged parallel to the row electrodes Y _1, Y _2, ..., Y _n (hereinafter, any row electrode Y And a glass substrate arranged in parallel with each other so that both electrodes are orthogonal to each other and face each other, and are fixed via a spacer (transparent adhesive or the like). Each row electrode Y is connected to a row electrode switching circuit 102 that is sequentially switched by a row electrode shift register (not shown) or the like. On the other hand, each column electrode X is connected to a column electrode switching circuit 103 which is sequentially switched and scanned by a column electrode shift register (not shown). At that time, the column electrodes X and the row electrodes Y are formed substantially transparent by using tin-doped indium oxide (ITO) or the like.

The electronic pen 105 has a tip electrode (not shown), and a high frequency power source 106 is connected to the tip electrode to apply a high frequency voltage.

The row electrode switching circuit 102 and the column electrode switching circuit 103 are the timing generation circuit 1
It is connected to 04. Further, an x coordinate detection circuit 107 and ay coordinate detection circuit 108 are connected to the timing generation circuit 104. The x-coordinate detection circuit 107
Is a signal from the timing generation circuit 104 and the x-operational amplifier 1 from the column electrode switching circuit 103.
The electronic pen 1 based on the signal input via the electronic pen 1
The x coordinate of the tip of 05 is detected and an x coordinate signal representing the x coordinate is output. Similarly, the y-coordinate detection circuit 108
Outputs a y coordinate signal representing the y coordinate of the tip of the electronic pen 105.

The electrostatic induction tablet 101 thus constructed has a light transmittance of about 85%. Therefore, even if the electrostatic induction tablet 101 is laminated on the liquid crystal display, the display screen of the liquid crystal display can be seen through the electrostatic induction tablet 101. Therefore, as described above, the electrostatic induction tablet 101 is laminated on the liquid crystal display to form a display unit integrated tablet device, and the coordinates on the liquid crystal display are pen-input by the electrostatic induction tablet 101 and the electronic pen 105. You can do it.

The electrostatic induction tablet 101 having the above structure and its drive unit operate as follows. That is, first, shift data and a clock signal are sent from the timing generation circuit 104 to the shift register that drives each switch of the column electrode switching circuit 103. Then, the shift register generates the column electrode scanning signals x ₁ , ..., X _m as shown in FIG. 24, and the column electrode scanning signals x ₁ ,.
…, X _m scan pulse, column electrode switching circuit 1
The switches 03 are sequentially driven to be switched to the x-operational amplifier 110 side. Next, in the same manner, each switch of the row electrode switching circuit 102 is sequentially switched to the y operational amplifier 109 side based on the scanning pulse of the row electrode scanning signals y ₁ , ..., Y _n as shown in FIG.

At that time, the electrostatic induction tablet 101 is used.
The electronic pen 105 is brought close to the surface of the. Then, since the tip electrode of the electronic pen 105 and the column electrode X and the row electrode Y are coupled by the floating capacitance, respectively, the high frequency power supply 106
A voltage is induced in each column electrode X and each row electrode Y due to the high frequency voltage applied to the tip electrode of the electronic pen 105 from. As a result, x operational amplifier 110
25 from the y and operational amplifiers 109.
A voltage signal as shown in (a) is output.

Incidentally, the above-mentioned x-operational amplifier 11
The waveform of the voltage signal output from the 0 or y operational amplifier 109 is such that the switch connected to the column electrode X or the row electrode Y directly under the electronic pen 105 is switched to the x operational amplifier 110 or the y operational amplifier 109 side. The maximum value is reached. Here, the impedance on the input side of the x-operational amplifier 110 and the y-operational amplifier 109 is set sufficiently higher than the impedance on the lead wire force side. Therefore, a high induced voltage can be obtained.

Thus, each column electrode X and each row electrode Y is
The coordinates of the tip of the electronic pen 105 are detected based on the induced voltage induced on the electronic pen 105 as described below. That is, the output from the x-operational amplifier 110 and the y-operational amplifier 109 is shown in FIG.
The induced voltage signal having a waveform as shown in FIG. 5 (a) is amplified as necessary and then rectified to be a signal having a waveform as shown in FIG. It is input to the detection circuit 107 or the y coordinate detection circuit 108.

The x-coordinate detection circuit 107 is based on a clock signal from the timing generation circuit 104 and a signal from the x-operational amplifier 110 as shown in FIG. Scan signal x ₁ , ..., x _m
Column electrode switching circuit 103 based on the scanning pulse of
Operational amplifier 1 from the start of scanning
The time until the peak of the signal from 10 is input (Fig. 2
Measure Ts in 5 (b). Then, based on this measurement value, an x coordinate signal representing the x coordinate of the tip of the electronic pen 105 is output. Similarly, the y-coordinate detection circuit 10
Reference numeral 8 measures the time from the start of scanning of the row electrode switching circuit 102 until the peak of the signal from the y operational amplifier 109 is input. Then, based on this measured value, a y-coordinate signal representing the y-coordinate of the tip of the electronic pen 105 is output. The time Ts at that time is measured by a shift register for driving the row electrode switching circuit 102 or a column electrode switching circuit 103.
It is measured by counting the number of pulses of the clock signal applied to the shift register that drives the.

As described above, the electrostatic induction tablet 1 described above.
Although 01 has a relatively simple structure, it can obtain the tip coordinates of the electronic pen 105 with high accuracy, and is often used in small computers and the like.

[0013]

The electrostatic induction tablet 101 and the liquid crystal display as described above are stacked to display a pixel on the liquid crystal display corresponding to the tip coordinates of the electronic pen 105 on the electrostatic induction tablet 101. A tablet device integrated with such a display unit is configured. This tablet device integrated with a display unit scratches the surface of the electrostatic induction tablet 101 with the tip of the electronic pen 105 to display characters and figures input by the pen on the display screen of the liquid crystal display, thereby making it possible to use a ballpoint pen or the like on paper. You can input characters and figures as if you were writing with a writing instrument.

However, the above-mentioned display-integrated type tablet device has the following problems. First, while looking at the display screen of the liquid crystal display, the electronic pen 10
When the surface of the electrostatic induction tablet 101 is scratched by 5, the display screen of the liquid crystal display is difficult to see. That is, as described above, the column electrodes X and the row electrodes Y of the electrostatic induction tablet 101 are formed of ITO or the like on the transparent substrate such as glass or plastic to be substantially transparent. However, the light transmittance of the electrode thus formed is about 85%, which is not so high as compared with the light transmittance of the substrate and is cloudy. The electrodes are regularly arranged in a grid pattern. Therefore, the electrodes X ₁ of the electrostatic induction tablet 101,
_{X 2, ..., X m,} Y 1, Y 2, ..., Y n is noticeable beyond expectation. This phenomenon is particularly remarkable in a simple display unit integrated tablet having no backlight.

The display screen of the liquid crystal display has electrodes X ₁ , X ₂ , ..., X _m , of the electrostatic induction tablet 101.
The area covered by Y ₁ , Y ₂ , ..., Y _n is relatively large.
As a result, there are problems that the display screen of the liquid crystal display becomes dark and the contrast becomes low.

Further, since the liquid crystal display and the electrostatic induction tablet 101 are separately configured, when the liquid crystal display and the electrostatic induction tablet 101 are laminated and assembled together, the liquid crystal display and the electrostatic induction tablet 101 are integrated. The position corresponding to the tablet 101 may shift.
In this case, the position on the LCD display that you entered with the pen
Due to this pen input (the position designated by the tip of the electronic pen 105) and the position of the pixel displayed on the display screen of the liquid crystal display, a deviation occurs. Therefore, there is a problem in that it is not possible to input characters and figures as if writing on paper with a writing instrument such as a ballpoint pen.

Furthermore, since the liquid crystal display and the electrostatic induction tablet 101, which are separately formed, are integrally laminated, the obtained display-integrated tablet becomes large and heavy. Therefore, there is also a problem that it hinders the miniaturization of small computers and word processors desired by consumers. There is also a problem that it becomes a factor of cost increase.

SUMMARY OF THE INVENTION An object of the present invention is to provide a display-integrated type tablet device in which the position on the display screen can be easily seen on the display screen and the size and cost can be easily reduced. .

[0019]

In order to achieve the above object, the display-integrated type tablet of the first invention comprises a plurality of segment electrodes arranged in parallel and a plurality of segment electrodes arranged in parallel at right angles to the segment electrodes. A liquid crystal panel having a common electrode and driven by a duty type driving method, and an electronic pen having an electrode to which a high frequency voltage is applied by being coupled to the segment electrodes and common electrodes of the liquid crystal panel by stray capacitance, A display control circuit for outputting a display control signal and display data for displaying an image on a pixel matrix formed by intersection regions of a plurality of segment electrodes and a plurality of common electrodes of the liquid crystal panel, and the segment electrodes of the liquid crystal panel And a detection control circuit that outputs a scanning control signal for scanning the common electrode, and a control circuit. The display control circuit side is switched and selected in the display period to output the display control signal and the display data from the display control circuit while the detection control circuit side is switched and selected in the coordinate detection period. A switching circuit for outputting a scanning control signal from the detection control circuit, and a common electrode drive signal for sequentially selecting the common electrode based on the display control signal from the switching circuit during the display period. , A common drive circuit that sequentially scans the common electrodes without displaying an image on the pixel matrix based on a scan control signal from the switching circuit during the coordinate detection period, and a switching circuit from the switching circuit during the display period. Pixel related to the common electrode selected by the common electrode drive signal based on the display control signal and the display data While generating a segment electrode drive signal for displaying, a segment drive circuit for sequentially scanning the segment electrodes without displaying an image on the pixel matrix based on the scan control signal from the switching circuit during the coordinate detection period. When,
A voltage detection circuit for detecting an induced voltage induced in the scan common electrode by the common drive circuit or the scan segment electrode by the segment drive circuit due to the high frequency voltage applied to the electrode of the electronic pen during the coordinate detection period; , The induced voltage of each common electrode and the induced voltage of each segment electrode detected by the voltage detection circuit are input, and the electronic pen tip of the electronic pen tip is subjected to a predetermined procedure based on the input induced voltage in the coordinate detection period. A coordinate detection circuit that detects coordinates and outputs an x-coordinate signal or a y-coordinate signal is provided, and the display period and the coordinate detection period are appropriately set by the control circuit, and the liquid crystal is displayed in the set display period. While displaying an image on the pixel matrix of the panel, the pixel matrix is displayed during the coordinate detection period. It is characterized by detecting the position of the tip of the electronic pen in no on the liquid crystal panel to display an image on the helix.

According to a second aspect of the invention, in the display-integrated type tablet device according to the first aspect, the common drive circuit and the segment drive circuit each have a voltage transmitting / receiving means, and the generated common is generated during the display period. While the voltage based on the electrode drive signal or the segment voltage drive signal is sent to each of the common electrodes or each of the segment electrodes through the voltage transmission / reception means, the induced voltage from the scan common electrode or the scan segment electrode is generated during the coordinate detection period. Is transmitted to the voltage detection circuit via the voltage transmission / reception means.

A third aspect of the invention is the display-integrated type tablet device according to the second aspect of the invention, wherein the voltage transmitting / receiving means has one end commonly connected to the power supply section and the voltage detection circuit, and the other end individually. Common electrode or a plurality of bidirectional analog switch circuits connected to individual segment electrodes. During the display period, a predetermined voltage from the power supply unit on the one end side is taken in and the common electrode on the other end side is taken in. Alternatively, while being sent to the segment electrode, during the coordinate detection period, the induced voltage of the common electrode or the segment electrode on the other end side is captured and sent to the voltage detection circuit on the one end side.

According to a fourth aspect of the invention, in the display-integrated type tablet device according to any one of the first to third aspects, at least one of the common drive circuit and the segment drive circuit, which is farther from the electronic pen. One of the drive circuits that scans the electrodes of (1) simultaneously scans a predetermined number of electrodes, which is larger than the number of electrodes that are simultaneously scanned by the other drive circuit, during the coordinate detection period.

A fifth aspect of the present invention is the display-integrated type tablet device according to any one of the first to fourth aspects, wherein one of the common electrodes or the segment electrodes that is farther from the electronic pen is the electrode. While scanning, the high frequency voltage of the first voltage is applied to the electrodes of the electronic pen,
It is characterized in that it is provided with a high frequency power source for applying a high frequency voltage of a second voltage lower than the first voltage when the other electrode is scanned.

A sixth aspect of the invention is the display-integrated type tablet device according to any one of the first to fifth aspects of the invention, wherein the coordinate detection circuit has an amplifier, and one of the common electrode or the segment electrode is the one described above. When obtaining the coordinates of the tip of the electronic pen on the basis of the induced voltage induced in the electrode farther from the electronic pen, the coordinates of the tip of the electronic pen are obtained after amplifying the induced voltage by the first amplification factor. When obtaining the electronic pen tip coordinate based on the induced voltage induced on the other electrode, the electronic pen tip coordinate is calculated after amplifying the induced voltage by a second amplification rate smaller than the first amplification rate. It is characterized by seeking.

A seventh aspect of the present invention is the display-integrated type tablet device according to any one of the first to sixth aspects, wherein the voltage detecting circuit has a voltage applying means, and the voltage detecting circuit is provided in the coordinate detecting period. The voltage applying means applies the same voltage as the non-scanning common electrode or the non-scanning segment electrode to the scanning common electrode or the scanning segment electrode.

An eighth aspect of the invention is the display-integrated type tablet device according to any one of the first to seventh aspects of the invention, in which the direction of application of the voltage applied to the liquid crystal of each pixel in the pixel matrix during the display period. A display AC signal generation unit that generates a display AC signal for setting the inversion time point;
Detecting AC for inverting the application direction of the voltage applied to the liquid crystal of each pixel in the coordinate detection period and inverting the application direction of the voltage at a time other than the common electrode scanning period and the segment electrode scanning period. The common drive circuit and the segment drive circuit are each provided with a detection alternating current signal generation unit that generates a signal, and the application direction of the voltage applied to the liquid crystal of each pixel is based on the display alternating current signal in the display period. While the common electrode drive signal or the segment electrode drive signal which is inverted is generated, it is applied to the liquid crystal at the time other than the common electrode scanning period and the segment electrode scanning period based on the detected alternating current signal in the coordinate detection period. A common electrode scanning signal or segment electrode scanning signal that reverses the voltage application direction is generated. It is.

Further, the display-integrated type tablet device of the ninth invention is such that a plurality of gate bus line electrodes arranged in parallel on the transparent substrate and a plurality of sources arranged in parallel to and orthogonal to the gate bus line electrodes. A control terminal is connected to the gate bus line electrode while having a bus line electrode, and an input terminal is connected to the source bus line electrode and driven by a plurality of active elements arranged at intersections of the bus line electrodes. An active matrix type liquid crystal panel, and an electrode, which is located on the transparent substrate side having the active element in the liquid crystal panel, is coupled to the gate bus line electrode and the source bus line electrode by a stray capacitance and to which a high frequency voltage is applied. An electronic pen having a tip, a plurality of gate bus line electrodes and a plurality of sources in the liquid crystal panel. A display control circuit for outputting a display control signal and display data for displaying an image in a pixel matrix formed by a plurality of regions surrounded by a bus line electrode, and a gate bus line electrode and a source bus line electrode of the liquid crystal panel. A detection control circuit for outputting a scanning control signal for scanning the display control circuit, which is controlled by the control circuit and switches and selects the display control circuit side in the display period to display the display control signal and the display data from the display control circuit. On the other hand, based on the display control signal from the switching circuit during the display period, the switching circuit that outputs the scanning control signal from the detection control circuit by selecting the detection control circuit side during the target detection period. While generating a gate bus line electrode drive signal for sequentially selecting the gate bus line electrodes, A gate drive circuit that sequentially scans the gate bus line electrodes without operating the active element based on a scan control signal from the switching circuit during the coordinate detection period, and a display from the switching circuit during the display period. A source bus line electrode drive signal for displaying a pixel associated with the gate bus line electrode selected by the gate bus line electrode drive signal is generated based on a control signal and display data, while the switching is performed during the coordinate detection period. A source drive circuit that sequentially scans the source bus line electrodes based on a scan control signal from the circuit, and a scan by the gate drive circuit due to a high frequency voltage applied to the electrodes of the electronic pen during the coordinate detection period. Induced by the gate bus line electrode or the scanning source bus line electrode by the above source drive circuit. The voltage detection circuit for detecting the induced voltage, the induced voltage of each gate bus line electrode and the induced voltage of each source bus line electrode detected by the voltage detection circuit are input, and are input during the coordinate detection period. A coordinate detection circuit for detecting the coordinates of the tip of the electronic pen according to a predetermined procedure based on the induced voltage and outputting an x-coordinate signal or a y-coordinate signal is provided, and the display period and the coordinate detection period are controlled by the control circuit. Is appropriately set, and an image is displayed on the pixel matrix of the liquid crystal panel in the set display period, while detecting the tip position of the electronic pen on the liquid crystal panel in the coordinate detection period. It has a feature.

A tenth aspect of the invention is the display-integrated type tablet device according to the ninth aspect, wherein at least one drive circuit of the gate drive circuit and the source drive circuit is:
During the coordinate detection period, a predetermined number of bus line electrodes in the liquid crystal panel are simultaneously scanned.

The eleventh invention is the display-integrated tablet device according to any one of the first to tenth inventions, wherein the cycle of the high-frequency voltage applied to the electrode of the electronic pen is in the coordinate detection period. It is characterized by being shorter than the electrode scanning period of the common drive circuit and the segment drive circuit, the gate drive circuit and the source drive circuit.

The twelfth invention is the display-integrated type tablet device according to any one of the first to eleventh inventions, wherein the coordinate detection circuit has the same frequency as the high frequency voltage applied to the electrode of the electronic pen. In the coordinate detection period, the high frequency of the induced voltage induced in the common electrode and the segment electrode, the gate bus line electrode, and the source bus line electrode, which has a filter for separating frequency components, is detected. The component is separated by the filter, and the coordinates of the tip of the electronic pen are detected by a predetermined procedure based on the separated high frequency component.

A thirteenth invention is the display-integrated tablet device according to any one of the first to twelfth inventions, wherein a high-frequency power supply for supplying a high-frequency voltage to the electrodes of the electronic pen is a high-frequency voltage generator. It is characterized in that it is configured in the electronic pen having a power supply for power supply and an active element.

A fourteenth invention is the display-integrated tablet device according to the thirteenth invention, wherein the electronic pen has an input detecting means for detecting the start of pen input and outputting a detection signal. The high-frequency voltage generating power supply is characterized by generating a high-frequency voltage based on a detection signal from the input detecting means.

The fifteenth invention is characterized in that, in the display-integrated type tablet device according to any one of the first to fourteenth inventions, the electrodes of the electronic pen are covered with a dielectric.

The display-integrated tablet device according to the sixteenth aspect of the invention is a plurality of gate bus line electrodes arranged in parallel on the transparent substrate and a plurality of sources arranged in parallel to each other at right angles to the gate bus line electrodes. A control terminal is connected to the gate bus line electrode while having a bus line electrode, and an input terminal is connected to the source bus line electrode and driven by a plurality of active elements arranged at intersections of the bus line electrodes. And an active matrix type liquid crystal panel having a high input impedance, which is located on the transparent substrate side having the active element in the liquid crystal panel and is coupled to the gate bus line electrode and the source bus line electrode by stray capacitance. An electronic pen having a plurality of gate bus line electrodes and a plurality of gate bus line electrodes in the liquid crystal panel; A display control circuit for outputting a display control signal and display data for displaying an image in a pixel matrix constituted by a plurality of regions surrounded by a bus line electrode, and a gate bus line electrode and a source bus line electrode of the liquid crystal panel. A detection control circuit for outputting a scanning control signal for scanning the display control circuit, which is controlled by the control circuit and switches and selects the display control circuit side in the display period to display the display control signal and the display data from the display control circuit. While outputting, on the basis of the display control signal from the switching circuit during the display period, and a switching circuit for switching and selecting the detection control circuit side in the coordinate detection period to output the scanning control signal from the detection control circuit. To generate a gate bus line electrode drive signal for sequentially selecting the gate bus line electrodes. A gate drive circuit that generates a gate bus line electrode scanning signal for sequentially scanning the gate bus line electrodes without operating the active element based on a scanning control signal from the switching circuit during the coordinate detection period. , A source bus line electrode drive signal for displaying a pixel related to a gate bus line electrode selected by the gate bus line electrode drive signal based on a display control signal and display data from the switching circuit in the display period. On the other hand, a source driving circuit that generates a source bus line electrode scanning signal for sequentially scanning the source bus line electrodes based on a scanning control signal from the switching circuit during the coordinate detection period, and the gate driving circuit. And the source drive circuit from the gate bus line electrode or source bus line An induced voltage induced in the electrode of the electronic pen due to each scanning signal input to the electrode is input, and in the coordinate detection period, a predetermined procedure is performed based on the input induced voltage from the electronic pen. A coordinate detection circuit for detecting the coordinates of the tip of the electronic pen and outputting an x-coordinate signal or a y-coordinate signal is provided, and the display period and the coordinate detection period are appropriately set by the control circuit. An image is displayed on the pixel matrix of the liquid crystal panel during the display period, while the tip position of the electronic pen on the liquid crystal panel is detected during the coordinate detection period.

A seventeenth invention is the display-integrated tablet device according to the sixteenth invention, wherein the gate drive circuit superimposes a coordinate detection signal on a selection pulse in the gate bus line electrode drive signal during the display period. Generates a gate bus line electrode drive signal, the coordinate detection circuit has a filter for separating the coordinate detection signal component of the induced voltage input from the electronic pen, and outputs from the gate drive circuit during the display period. The coordinate detection signal component of the induced voltage induced in the electrode of the electronic pen by the gate bus line electrode drive signal in which the coordinate detection signal is superimposed on the selected pulse is separated by the filter, and the separated coordinate detection signal is obtained. The y-coordinate of the tip of the electronic pen is detected by a predetermined procedure based on the component.

An eighteenth invention is the display-integrated tablet device according to any one of the first to seventeenth inventions, wherein the illuminating means for irradiating the liquid crystal panel from the rear is under the control of the control circuit. When driven, the control circuit controls the switching circuit to irradiate the display period only during the set period.

[0037]

According to the first aspect of the invention, the display control circuit side is switched and selected by the switching circuit according to the control of the control circuit, and the display period starts. Then, the display control signal and the display data from the display control circuit are output from the switching circuit. Then, the common drive circuit generates a common electrode drive signal for sequentially selecting the common electrodes of the liquid crystal panel based on the display control signal from the switching circuit. On the other hand, by the segment drive circuit,
A segment electrode drive signal for displaying a pixel associated with the common electrode selected by the common electrode drive signal is generated based on the display control signal and the display data from the switching circuit. Thus, in the display period, the pixels in the rows sequentially selected in the pixel matrix of the liquid crystal panel based on the generated common electrode drive signal and segment electrode drive signal are duty-type display methods according to display data. Is displayed.

Further, according to the control of the control circuit, the detection control circuit side is switched and selected by the switching circuit to enter the coordinate detection period. Then, the detection control signal from the detection control circuit is output from the switching circuit. Then, based on the detection control signal from this switching circuit,
The segment driving circuit scans the segment electrodes without displaying an image on the pixel matrix of the liquid crystal panel. Then, the induced voltage induced in the scanning segment electrode due to the high frequency voltage applied to the electrode of the electronic pen coupled to the segment electrode by the stray capacitance is detected by the voltage detection circuit.

When the induced voltage of each segment electrode thus detected is input to the coordinate detection circuit, during the coordinate detection period, the coordinate detection circuit performs a predetermined procedure based on the input induced voltage. The x coordinate of the tip of the electronic pen is detected, and the x coordinate signal is output.

Similarly, on the basis of the detection control signal from the switching circuit, the common drive circuit sequentially scans the common electrodes without displaying an image on the pixel matrix of the liquid crystal panel, and the common voltage is induced by the voltage detection circuit. The voltage is detected. Then, the coordinate detection circuit detects the y-coordinate of the tip of the electronic pen in a predetermined procedure based on the input induced voltage from the electronic pen and outputs the y-coordinate signal. Thus, during the coordinate detection period, the liquid crystal panel operates as an electrostatic induction tablet and the tip position of the electronic pen is detected using the liquid crystal panel.

In the second invention, the common drive circuit and the segment drive circuit generate a common electrode drive signal or a segment electrode drive signal in the display period via the voltage transmitting / receiving means of each of the drive circuits. A voltage based on this is sent to each of the common electrodes or each of the segment electrodes. Further, in the coordinate detection period, the voltage of the scanning common electrode or the scanning segment electrode is sent to the voltage detecting means via the voltage sending / receiving means. Thus, the application of the voltage to the common electrode or the segment electrode during the display period and the reading of the induced voltage of the common electrode or the segment electrode during the coordinate detection period are performed.

In the third aspect of the invention, during the display period, the bidirectional analog switch circuit forming the voltage transmitting / receiving means receives a predetermined voltage from the power supply unit connected to one end of the bidirectional analog switch circuit. It is delivered to each common electrode or segment electrode connected to the end side.
On the other hand, in the coordinate detection period, the induced voltage of each common electrode or segment electrode connected to the other end side is taken and sent to the voltage detection circuit connected to the one end side. Thus, the application of the voltage to the common electrode or the segment electrode during the display period and the reading of the induced voltage of the common electrode or the segment electrode during the coordinate detection period are performed.

In the fourth aspect of the invention, in the coordinate detection period, one of the common drive circuit and the segment drive circuit which inputs a scanning signal to at least the electrode farther from the electronic pen is used. , A predetermined number of electrodes, which is larger than the number of electrodes simultaneously scanned by the other driving circuit, are simultaneously scanned. Therefore, the level of the induced voltage induced in the electrode located farther from the electronic pen is increased. Thus, in the coordinate detection period, the induced voltage is prevented from decreasing when scanning the electrode farther from the electronic pen, and the x-coordinate and the y-coordinate of the tip of the electronic pen are stable. To be detected.

Further, in the fifth invention, during scanning of the common electrode or the segment electrode, whichever is farther from the electronic pen, is scanned by the high frequency power source during the coordinate detection period. The high frequency voltage of the first voltage is applied to the electrodes of the. On the other hand, when the other electrode is scanned, a high frequency voltage of a second voltage lower than the first voltage is applied. Therefore, the level of the induced voltage induced in the electrode located farther from the electronic pen is increased. Thus, during the coordinate detection period, the induced voltage is prevented from decreasing when scanning the electrode farther from the electronic pen, and the x coordinate and the y coordinate of the tip of the electronic pen are stabilized. Detected.

In the sixth aspect of the invention, when the tip coordinate of the electronic pen is detected based on the induced voltage induced in the common electrode or the segment electrode, whichever is farther from the electronic pen, The coordinate detection circuit obtains the coordinates of the tip of the electronic pen based on the induced voltage after being amplified by the first amplification factor. On the other hand, when detecting the coordinates of the tip of the electronic pen on the basis of the induced voltage induced on the other electrode, after being amplified by the coordinate detection circuit by the second amplification factor smaller than the first amplification factor. The coordinate of the tip of the electronic pen is obtained based on the induced voltage of
Thus, during the coordinate detection period, the coordinate detection accuracy is prevented from being lowered when scanning the electrode farther from the electronic pen, and the x-coordinate and the y-coordinate of the tip of the electronic pen are stable with the same accuracy. Then detected.

In the seventh invention, when the common electrode or the segment electrode is scanned by the common electrode driving circuit and the segment electrode driving circuit in the coordinate detecting period, the voltage applying means included in the voltage detecting means causes The same voltage as the non-scanning common electrode or the non-scanning segment electrode is applied to the scanning common electrode or the scanning segment electrode. Thus, when the common electrode or the segment electrode is scanned, the voltage of the scanning electrode is stably maintained at the non-scanning voltage.

In the eighth aspect of the invention, in the display period, the display AC signal generation unit is used to set the display AC for setting the time at which the voltage applied to the liquid crystal of each pixel in the pixel matrix is reversed. A signal is generated. Then, on the basis of the generated display alternating signal, the common drive circuit and the segment drive circuit invert the application direction of the voltage applied to the liquid crystal of each pixel, and the common electrode drive signal and the common electrode scan. A signal is generated. Thus, in the display period, when an image is displayed on the pixel matrix of the liquid crystal panel by the duty type drive method based on the generated common electrode drive signal and segment electrode drive signal, it is applied to each pixel. The application direction of the voltage is reversed to prevent the life of the liquid crystal from being shortened due to electrolysis.

On the other hand, in the coordinate detection period, the detection AC signal generation section sets the application direction reversal time point of the voltage applied to the liquid crystal of each pixel except the common electrode scanning period and the segment electrode scanning period. At this time point, a detection AC signal for inverting the application direction of the voltage is generated. Then, based on the generated detection alternating signal, both electrodes are scanned by the common drive circuit and the segment drive circuit so that the application direction of the voltage applied to the liquid crystal of each pixel is reversed. Thus, in the coordinate detection period, when scanning the common electrode and the segment electrode, the application direction of the voltage applied to the liquid crystal of each pixel is reversed at a time other than the common electrode scanning period and the segment electrode scanning period. As a result, the life of the liquid crystal is prevented from being shortened.

Further, in the ninth invention, similarly to the case of the display-integrated type tablet device of the first invention, in the display period, the gate bus line electrode drive signal and the source drive circuit generated by the gate drive circuit. On the basis of the source bus line electrode drive signal generated by, the pixels of the sequentially selected rows of the pixel matrix of the active matrix type liquid crystal panel are displayed according to the display data.

On the other hand, during the coordinate detection period, the gate bus line electrodes or the source bus line electrodes are sequentially scanned by the gate drive circuit and the source drive circuit without operating the active elements. Then, the induced voltage induced in the gate bus line electrode or the source bus line electrode due to the high frequency voltage applied to the electrode of the electronic pen is detected by the voltage detection circuit, and the coordinate is calculated based on the detected induced voltage. The detection circuit detects the coordinates of the tip of the electronic pen.

In the tenth aspect of the invention, a predetermined number of electrodes in the liquid crystal panel are simultaneously scanned by at least one of the gate drive circuit and the source drive circuit during the coordinate detection period. As a result, a high induced voltage is detected by the voltage detection circuit. Then, the coordinate detection circuit detects the coordinates of the tip of the electronic pen based on the high induced voltage from the scan electrode. Thus, in the coordinate detection period, when detecting the tip coordinates of the electronic pen using the liquid crystal panel of the high-density pixel matrix with a small stray capacitance coupling the electrode of the liquid crystal panel and the electrode of the electronic pen, The tip coordinates of the electronic pen are accurately detected based on the high induced voltage detected by scanning the predetermined number of electrodes at the same time.

Further, in the eleventh invention, during the coordinate detection period, a high frequency voltage having a cycle shorter than the electrode scanning cycle of the common drive circuit, the segment drive circuit, the gate drive circuit and the source drive circuit is applied to the electronic pen. The induced voltage induced in the gate bus line electrode or the source bus line electrode when applied to the electrodes is detected by electrode scanning with a period longer than the period of the high frequency voltage. In this way, the tip coordinate detection and the high-speed coordinate detection of the electronic pen in the liquid crystal panel of the high-density pixel matrix can be accurately performed.

In the twelfth aspect of the invention, in the coordinate detection period, the induced voltage induced in the common electrode and the segment electrode, the gate bus line electrode, and the source bus line electrode detected by the voltage detection circuit is set. The same high frequency component as the frequency of the high frequency voltage to the electronic pen is separated by the filter in the coordinate detection circuit. Then, the tip coordinates of the detection pen are accurately detected based on the separated high frequency components.

Further, in the thirteenth invention, a high frequency voltage is applied to the electrode of the electronic pen by the high frequency power source having the high frequency generating power source and the active element and configured in the electronic pen. In this way, a cordless high frequency voltage is applied to the electrodes of the electronic pen.

In the fourteenth aspect of the invention, when the input detecting means of the electronic pen detects the start of pen input and outputs a detection signal, the high frequency power source supplies the electronic pen based on the detection signal. A high frequency voltage for use is generated. Thus, the high frequency voltage is applied to the electronic pen only when necessary.

In the fifteenth aspect of the invention, the electrodes of the electronic pen are covered with a dielectric so that coordinate detection can be safely performed on an external electronic circuit or a human body.

Further, in the sixteenth invention, in the display period, the pixels in each row in the pixel matrix of the active matrix type liquid crystal panel which are sequentially selected based on the gate bus line electrode drive signal generated by the gate drive circuit, Display is performed according to the display data based on the source bus line electrode drive signal generated by the source drive circuit.

On the other hand, during the coordinate detection period, the gate bus line electrode scanning signal and the source bus line electrode scanning signal for sequentially scanning the gate bus line electrode and the source bus line electrode without operating the active element are driven by the gate drive. It is generated by the circuit and the source driving circuit and is output to the gate bus line electrode and the source bus line electrode. A coordinate detection circuit based on the induced voltage induced in the electrode of the electronic pen due to the gate bus line electrode scanning signal and the source bus line electrode scanning signal applied to the gate bus line electrode and the source bus line electrode. The tip coordinates of the electronic pen are detected by.

Further, in the seventeenth invention, the coordinate detection signal is superimposed on the selection pulse in the gate bus line electrode drive signal during the display period by the gate drive circuit in the display-integrated type tablet device of the sixteenth invention. A gate bus line electrode drive signal is generated and input to the gate bus line electrode. Then, the coordinate detection circuit separates the coordinate detection signal component of the induced voltage induced in the electrode of the electronic pen due to the gate bus line electrode drive signal in which the coordinate detection signal is superimposed on the selection pulse by the filter. Then, the y coordinate of the tip of the electronic pen is detected based on the separated coordinate detection signal component. Thus, in the coordinate detection period, the y-coordinate of the electronic pen is detected without driving the active element by applying the gate bus line electrode scanning signal to the gate bus line electrode.

In the eighteenth aspect of the invention, the illuminating means for illuminating the liquid crystal panel from the back is driven only under the control of the control circuit by the control circuit controlling the switching circuit to set the display period. Then, the liquid crystal panel is illuminated.

[0061]

The present invention will be described in detail below with reference to the embodiments shown in the drawings. <First Example> FIG. 1 is a block diagram of a display-integrated type tablet device in the present embodiment. This display-integrated tablet device constitutes a tablet device having an integrated display function by using the electrodes and drive circuit of the electrostatic induction tablet as the electrodes and drive circuit of the liquid crystal panel in the duty type liquid crystal display device. . Prior to the description of the display-integrated type tablet device according to the present embodiment, the duty type liquid crystal display device will be briefly described below.

FIG. 10 is a block diagram of a normal duty type liquid crystal display device. The liquid crystal panel 1 includes a transparent substrate on which a plurality of common electrodes Y ₁ , Y ₂ , ..., Y ₈ (hereinafter, any common electrode is referred to as Y) are arranged in parallel, and a plurality of segment electrodes X ₁ , X _2, ..., X ₄₀ (hereinafter, an arbitrary segment electrode to as X) is a transparent substrate which are arranged in parallel, a spacer or the like so that the common electrode Y and the segment electrode X perpendicular to face Are arranged at predetermined intervals. Liquid crystal is filled between the transparent substrates.
In this way, a pixel is formed in the region where the common electrode Y and the segment electrode X intersect. That is, the liquid crystal panel 1 has pixels of 40 dots × 8 dots arranged in a matrix and is driven by a duty type driving method.

The common electrodes Y ₁ , Y ₂ , ..., Y ₈ are respectively connected to the corresponding output terminals O1, O2, ..., O8 of the common drive circuit 2 '.
It is connected to the. Then, the common electrode Y is activated by the selection pulse of the common electrode drive signal output from each output terminal O1, O2, ..., O8 of the common drive circuit 2 ′ to select the row of the pixel matrix. On the other hand, the segment electrodes X ₁ , X ₂ , ..., X ₄₀ are connected to the corresponding output terminals O 1, O 2, ..., O ₄₀ of the segment drive circuit 3 ′, respectively. Then, from the output terminals O1, O2, ..., O40 of the segment drive circuit 3 ′ to the segment electrodes X ₁ , X ₂ ,.
A segment electrode drive signal corresponding to the display data is output to X ₄₀ . Then, each pixel in the row of the pixel matrix selected by the common electrode drive signal from the common drive circuit 2'is displayed according to the display data by the segment electrode drive signal from the segment drive circuit 3 '.

The common drive circuit 2'and the segment drive circuit 3'are connected to the display control circuit 4 as follows. That is, the shift data output terminal S of the display control circuit 4 is connected to the shift data input terminal DIO1 of the common drive circuit 2 '. The alternating signal output terminal FR of the display control circuit 4 is connected to the alternating signal input terminal YFR of the common drive circuit 2'and the alternating signal input terminal XFR of the segment drive circuit 3 '. In addition, the display control circuit 4
The clock output terminal CP1 of is connected to the clock input terminal YCK of the common drive circuit 2'and the latch pulse input terminal XLP of the segment drive circuit 3 '. The clock output terminal CP2 of the display control circuit 4 is connected to the clock input terminal XCK of the segment drive circuit 3 '. Also,
The display data output terminals D0 to D3 of the display control circuit 4 are connected to the display data input terminals XD0 to XD3 of the segment drive circuit 3 '.

The power supply circuit 5 uses bias power supplies V _{0 to} V ₅ of a plurality of levels used when the drive signals for driving the liquid crystal panel 1 are generated by the common drive circuit 2 ′ and the segment drive circuit 3 ′. 2'and the segment drive circuit 3 '. In the present liquid crystal display device, the bias power sources V _{0 to} V ₅ are set as follows. That is, V ₀ = 0.0V, V ₁ = 1.7V, V ₂ = 3.4V, V ₃ = 2
3.5V, V ₄ = 25.2V, V ₅ = 26.9V.

FIG. 11 is a detailed block diagram of the common drive circuit 2 '. Output terminals O1, O2, ..., the common electrode driving signal a from O8, b, ..., h is output, the common electrodes Y _1, Y ₂ corresponding liquid crystal panel 1, ..., is inputted to Y _8. The power supply circuit 5 is connected to the input terminals V0, V1, V4 and V5.
Bias power sources V ₀ , V ₁ , V ₄ and V ₅ are input from the bias power sources V ₀ , V ₁ , V ₄ and V ₅ , and the common electrode driving signal a, b, ..., H are generated.

The duty type liquid crystal display device having the above structure operates as follows. FIG. 12 is a timing chart of the common electrode drive signals a to h and the segment electrode drive signal. The operation of the duty type liquid crystal display device will be described below with reference to FIG. 12 with reference to FIGS. 10 and 11.

When the clock signal cp1 output from the clock output terminal CP1 in the display control circuit 4 is input to the clock input terminal YCK, the shift data of the display control circuit 4 is synchronized with the input clock signal cp1. The pulse of the shift data s output from the output terminal S is taken into the shift register 35 from the shift data input terminal DIO1. Then, the selection pulses of the corresponding common electrode drive signals a to h are sequentially output from the output terminals O1 to O8 corresponding to the pulse positions of the shift data s shifted by the shift register 35.

At this time, the common electrode drive signals a to h
Is generated by selecting one of the bias power supplies V _{0 to} V ₅ supplied from the power supply circuit 5 by the level shifter 36 based on the output signal of the shift register 35 and the AC signal fr, and via the output driver. Is output.

On the other hand, when the clock signal cp2 output from the clock output terminal CP2 of the display control circuit 4 is input to the clock input terminal XCK, the segment drive circuit 3'is synchronized with the input clock signal cp2. Then, the designated position of the segment electrode X is shifted. Then, the display data D _{0 to} D ₃ output from the display data output terminals D0 to D3 of the display control circuit 4 and input to the display data input terminals XD0 to XD3 of the segment drive circuit 3 ′ are
The bits corresponding to the shift positions in the register are sequentially fetched. Thereafter, this operation is repeated 10 times, and the display data for one row (40 pixels) of the pixel matrix is fetched into the register.

After that, the latch pulse input terminal XLP
The fetched display data D _{0 to} D ₃ are latched in synchronism with the clock signal cp1 input to the. And
A segment electrode drive signal corresponding to the latched display data D _{0 to} D ₃ is output from the output terminals O1 to O40 to the corresponding segment electrode X. The segment electrode drive signal at that time is generated according to the display data D _{0 to} D ₃ based on the bias power supplies V _{0 to} V ₅ supplied from the power supply circuit 5.

In this way, the common drive circuit 2'is
Selection pulse of common electrode drive signal a output from (a)
Common electrode Y ₁ selected and activated by
Each pixel according to (3) is displayed according to the display data by the segment electrode drive signal output from the segment drive circuit 3 '.

Hereinafter, the common electrodes Y ₂ and Y ₂ are selected in accordance with the selection pulses of the common electrode drive signals b to h from the common drive circuit 2 '.
When Y ₃ , ..., Y ₈ are sequentially selected and an image for one frame is displayed, the next pulse of the shift data s is again taken in from the shift data input terminal DIO1 of the common drive circuit 2 '. Then, the common drive circuit 2 ′, the segment drive circuit 3 ′, and the display control circuit 4 repeat the above-described operation to display an image for the next frame. Hereinafter, this operation is repeated to display an image on the liquid crystal panel 1.

That is, the image of the Nth frame is displayed during the period T ₁ in FIG. 12, and then the period T ₂
The image of the (N + 1) th frame is displayed during the period. In many cases, the number of frames displayed per unit time at that time is set to about 72 frames / second so that flicker does not occur.

In general, the common electrodes Y ₁ , Y of the liquid crystal panel 1
_2, ..., Y ₈ and the segment electrode X _1, X _2, ..., the application direction of the voltage to the liquid crystal in the intersections of the X ₄₀ continues to apply a constant voltage, the liquid crystal therebetween undergoes electrolysis liquid Shortens the life of. Therefore, in order to prevent this, it is output from the AC signal output terminal FR of the display control circuit 4 and is input to the AC signal input terminal YFR of the common drive circuit 2 ′ and the AC signal input terminal XFR of the segment drive circuit 3 ′. The application direction of the voltage applied to the liquid crystal is changed for each frame according to the level of the alternating signal fr. The above-mentioned operation will be described in more detail with reference to an actual example.

For example, the segment electrode drive signal A input to the odd-numbered segment electrodes X and the segment electrode drive signal B input to the even-numbered segment electrodes X.
Is assumed to have a waveform as shown in FIG. At that time,
It is assumed that the Nth frame image and the (N + 1) th frame image are the same image. As a result, each pixel in the liquid crystal panel 1 is displayed as shown in FIG.
In FIG. 13, the ∘ mark indicates a display pixel, while the X mark indicates a non-display pixel.

The reversal of the voltage applied to the liquid crystal is carried out as follows according to the level of the alternating signal fr. As shown in FIG. 12, when the level of the alternating signal fr is “L” (at time T ₁ ), an arbitrary common electrode Y
Common electrode drive signals a to select a display row in the pixel matrix of the liquid crystal panel 1 by activating
Select pulse voltage of h (hereinafter simply referred to as select voltage) is "V
₀ "to. Meanwhile, the common electrode drive signals a~h voltage for any of the common electrode Y inactive (hereinafter, referred to as non-selection voltage) is" a V ₄ ". By contrast, in the case of level "H" of the alternating signal fr (for time T _2),
Set the selection voltage to "V ₅ ". On the other hand, to "V _1" to non-selection voltage.

When the level of the alternating signal fr is "L" (time T ₁ ), the segment electrodes for displaying the display pixels of the selected display row in the pixel matrix of the liquid crystal panel 1 are displayed. driving signal a, and the "V _5" (the oN voltage in FIG. 12) voltage B. On the other hand, the voltage (off voltage in FIG. 12) of the segment electrode drive signals A and B for not displaying the non-display pixel of the selected display row is set to "V ₃ ".
To On the other hand, the level of the alternating signal fr is "H"
In the case of (at time T ₂ ), the on-voltage to the display pixel is set to “V ₀ ”. On the other hand, the off voltage to the non-display pixel is set to "V ₂ "
To

Switching of the selection voltages "V ₀ ", "V ₅ " and switching of the non-selection voltages "V ₄ ", "V ₁ " performed by the common drive circuit 2 ', and the segment drive circuit 3'. The switching of the applied voltages “V ₅ ” and “V ₀ ” to the display pixels and the switching of the applied voltages “V ₃ ” and “V ₂ ” to the non-display pixels are performed by the level change of the alternating signal fr. This is carried out by selecting one of the bias power supplies V _{0 to} V ₅ from the power supply circuit 5 by an analog switch which operates in synchronization.

As described above, in synchronization with the change in the level of the alternating signal fr between "L" and "H", the selection voltages of the common electrode driving signals a to h are set to "V ₀ " and "V" by the analog switch. At the same time as switching between V ₅ "and the voltage applied to the display pixel in the segment electrode drive signals A and B between" V ₅ "and" V ₀ ", the common electrode Y in the display pixel is The potential difference from the segment electrode X becomes (V ₅ −V ₀ ) regardless of the level of the alternating signal fr. On the other hand, the potential difference between the common electrode Y and the segment electrode X in the non-display pixel is (V ₃ −V ₀ ), (V ₄ −V ₃ ) when the level of the alternating signal fr is “L”. , (V ₅ −
V ₄ ), which is lower than the potential difference between the common electrode Y and the segment electrode X in the display pixel.

On the other hand, when the level of the alternating signal fr is "H", it is any _one of (V ₁ -V ₀ ), (V ₂ -V ₁ ), and (V ₅ -V ₂ ), both of which are This is lower than the potential difference between the common electrode Y and the segment electrode X in the display pixel.

Therefore, while the value of the potential difference (V ₅ −V ₀ ) is higher than the threshold value of the liquid crystal display voltage, the value of the potential difference (V ₅ −V ₁ ) and the value of the potential difference (V ₄ −V ₀ ) are the above threshold values. By setting the values of the bias power sources V _{0 to} V ₅ as follows, the liquid crystal panel 1 can be displayed regardless of the level of the alternating signal fr. Further, at that time, the application direction of the voltage between the common electrode Y and the segment electrode X is inverted in accordance with the inversion of the level of the alternating signal fr, so that the life of the liquid crystal is prevented from being shortened.

In the above description, the level of the alternating signal fr is inverted every frame to invert the voltage application directions of the common electrode drive signal and the segment electrode drive signal. However, the liquid crystal panel 1 has a large number of pixels, and in the case of a high-density liquid crystal panel having, for example, 640 pixels × 400 pixels, the voltage direction between the common electrode Y and the segment electrode X is frequently changed (for example, 1 for common electrode Y
It is inverted every time 3 rows are selected. In that case, since the total number of common electrodes Y is 400, the frame switching period and the level inversion period of the AC signal fr are not synchronized at all as shown in FIG. Therefore,
The direction inversion of the applied voltage in the image of one field is randomly dispersed, and there is an effect that no brightness unevenness due to the inversion of the application direction of the voltage applied to the pixel is seen at all.

[First Embodiment] Next, the display-integrated type tablet device in the present embodiment will be described. As shown in FIG. 23, in the electrostatic induction tablet 101, the electrodes arranged in parallel in one direction and the electrodes arranged in parallel in the direction orthogonal to the electrodes face each other with a minute gap. . Further, as shown in FIG. 10, in the liquid crystal panel of the duty type liquid crystal display device, the electrodes arranged in parallel in one direction and the electrodes arranged in parallel in the direction orthogonal to the electrodes are spaced at a minute interval. Are facing each other. Therefore,
In this embodiment, paying attention to this point, the row / column electrodes of the electrostatic induction tablet and the drive circuit for the row / column electrodes are connected to common / segment electrodes and common / segment electrodes in the liquid crystal panel of the duty type liquid crystal display device. By being also used as the drive circuit for the segment electrodes, a display-integrated type tablet device having an integrated display function is constructed.

As shown in FIG. 1, the display-integrated type tablet device according to the present embodiment is the same as the duty type liquid crystal display device shown in FIG. 10 except that the detection control circuit 6, the switching circuit 7, the x coordinate detection circuit 8 and the y coordinate detection circuit. 9, the control circuit 10 and the electronic pen 11 are added. The liquid crystal panel 1 also has an electrostatic induction tablet function, and hereinafter, the liquid crystal panel 1 in which the electrostatic induction tablet function is integrated.
(That is, conversely, an electrostatic induction tablet with a display function integrated) is simply called a liquid crystal panel.

Further, the common drive circuit 2 is provided with a mode signal input terminal MODE and a common electrode voltage read terminal G5, while the segment drive circuit 3 is provided with a shift data input terminal EIO1, a mode signal input terminal MODE and a segment electrode voltage read. A terminal H5 is provided. Then, the mode signal mode from the control circuit 10 is input to both mode signal input terminals MODE, and the operation mode of the common drive circuit 2 or the segment drive circuit 3 is switched. Further, the signal from the common electrode voltage read terminal G5 of the common drive circuit 2 is input to the y coordinate detection circuit 9 via the operational amplifier 13. Similarly, the signal from the segment electrode voltage read terminal H5 of the segment drive circuit 3 is supplied to the operational amplifier 14
Is input to the x-coordinate detection circuit 8 via.

The detection control circuit 6 operates in substantially the same manner as the timing generation circuit 104 in the drive section of the electrostatic induction tablet 101 shown in FIG. Further, the switching circuit 7 is based on the control of the control circuit 10,
The shift data s, the alternating signal fr, the clock signal cp1, and the clock signal cp2 from the display control circuit 4 and the shift data sd, the alternating signal frd, the clock signal cp1d, and the clock signal cp2d from the detection control circuit 6 are switched and selected. The shift data so, the alternating signal fro, the clock signal cp1o, and the clock signal cp2o are output to the common drive circuit 2 and the segment drive circuit 3.

Then, in the liquid crystal panel 1, the operation mode of the common drive circuit 2 and the segment drive circuit 3 is set to the display mode by the mode signal mode from the control circuit 10, and the display control circuit is set by the switching circuit 7. 4 is selected, the common electrode drive signals a to a from the common drive circuit 2 are selected.
An image is displayed on the pixel matrix as described above based on h and the segment electrode drive signals A and B from the segment drive circuit 3.

On the other hand, a mode signal from the control circuit 10
Depending on the mode, the operation mode of the common drive circuit 2 and the segment drive circuit 3 is switched to the coordinate detection mode described in detail later, and when each signal from the detection control circuit 6 is selected by the switching circuit 7, details will be described later. As described above, scanning for sequentially detecting the induced voltage signals induced in the common electrode Y and the segment electrode X due to the high frequency voltage applied to the tip electrode of the electronic pen 11 from the high frequency power supply 12 is performed. Of.

The x-coordinate detection circuit 8 and the y-coordinate detection circuit 9 operate in substantially the same manner as the x-coordinate detection circuit 107 and the y-coordinate detection circuit 108 in the drive section of the electrostatic induction tablet 101 shown in FIG. That is, the control circuit 10
From the operational amplifier 13 when scanning the segment signal X or the common electrode Y from the timing signal from the
The tip coordinates of the electronic pen 11 are detected on the basis of the signal output from 14.

In FIG. 1, the display control circuit 4, the detection control circuit 6, the switching circuit 7 and the control circuit 10 are shown.
Is divided into each block and expressed. However, in actual circuits, each of the above circuits is an LSI (Large Scale Integrated Circuit)
However, it cannot be strictly divided into the above blocks.

FIG. 2 is a detailed block diagram of an electrode drive circuit for the liquid crystal panel 1 used as the common drive circuit 2 or the segment drive circuit 3. The following description of the electrode drive circuit will be given by taking the case where it is used as the segment drive circuit 3 as an example.

The structure of the electrode drive circuit (segment drive circuit 3) in this embodiment is the same as that of the liquid crystal panel drive circuit as shown in FIG. 11 (the liquid crystal panel drive circuit in FIG. 11 is the common drive circuit 2 '). Differ in terms of. That is, the analog switch Tr ₅ dedicated for reading the voltage of the segment electrode X ₁ to X ₄₀ which is connected to the output terminals O1~O40 sequentially provided, the analog switches T
The output of r ₅ is the common segment electrode voltage readout terminal H 5
Connected to. In the segment drive circuit 3 in FIG. 2, the input terminal V1, V4 of the not used bias source V _1, V ₄ are omitted.

The control circuit 10 is connected to the mode terminal MODE.
When the mode signal mode from 1 to 3 is input and the level of the mode signal mode becomes “H”, the operation mode of the segment drive circuit 3 becomes the coordinate detection mode. On the other hand, the mode signal mode
When the level becomes low, the operation mode of the segment drive circuit 3 becomes the display mode. Further, the scan mode signal scan from the control circuit 10 is input to the control terminal S / C.

The scan mode signal scan is a signal for controlling the scan mode of the segment drive circuit 3. Hereinafter, the scan mode will be described in detail. The first scanning mode in the case where the level of the scanning mode signal scan is "H" is a scanning mode implemented as follows during the display period.

That is, the display data input terminals XD0 to XD
Display data D ₀ serially input to D3 by 4 bits
o to D ₃ o are sequentially sent to the data latch circuit 15 in synchronization with the clock signal cp2o input to the clock input terminal XCK. In this way, the data latch circuit 15 has a capacity of one line.
When the display data of 40 pixels is latched, all the display data are simultaneously transferred to the level shifter 18 via the line latch circuit 16 in synchronization with the clock signal cp1o input to the latch pulse input terminal XLP. . From the level shifter 18, the analog switch control signals s ₁ to
Forty analog switch control signals (for example, analog switch control signals s ₄ , ...) Selected according to the contents of all the display data transferred out of s ₄ are output.

Then, the analog switch (for example, analog switch Tr ₄ ) to which the individual analog switch control signal from the level shifter 18 is input is turned "on", and the analog switch corresponding to this "on" is responded. A bias power supply (eg, bias power supply V ₅ ) is output from the corresponding output terminal (eg, output terminal O1) to the segment electrode X (eg, segment electrode X ₁ ). That is, the first scanning mode is simply a mode in which the electrodes are collectively scanned.

On the other hand, the second scanning mode when the level of the scanning mode signal scan is "L" is a scanning mode which is carried out as follows during the coordinate detection period.

That is, the shift data input terminal EI
The pulse of the shift data so input to O1 is taken into the first register in the shift register 17 in synchronization with the clock signal cp1o. And the next clock signal cp1o
In synchronization with the shift data so stored in the first to 40th registers of the shift register 17 (in this case, the shift data so in the first register is “H”,
The shift data so of the 2nd to 40th registers are "L") are transferred to the level shifter 18 all at once. And
From the level shifter 18, an analog switch control signal (for example, shift data s) corresponding to the content of the transferred shift data so among the analog switch control signals s _{1 to} s ₄ is transmitted.
If o is "H", analog switch control signal s ₅ ; if shift data so is "L", analog switch control signal s ₄ )
Is output.

[0100] Then, the analog switch control signal s ₅ output from the level shifter 18 from the analog switch Tr ₅ input, the voltage of the corresponding segment electrode X is output to the segment electrode voltage reading terminal H5. On the other hand, from the analog switch Tr ₄ to which the analog switch control signal s ₄ is input, the bias power supply V ₅ is output to the corresponding segment electrode X. Thus, the voltage of the segment electrode X ₁ is read from the output terminal O ₁ , and the segment electrodes X _{2 to} X are output from the other output terminals O 2 to O 40.
_The non-scanning voltage V ₅ is output to ₄₀ . At the same time, the pulse of the shift data so fetched in the first register of the shift register 17 is shifted to the second register.

Similarly, the next clock signal cp1o
In synchronization with the above, the voltage of the segment electrode X ₂ is read from the output terminal O ₂ and the non-scanning voltage V ₅ is output from the other output terminals O 1, O 3 to O 40 to the segment electrodes X ₁ , X _{3 to} X ₄₀ . At the same time, the pulse of the shift data so stored in the second register of the shift register 17 is shifted to the third register. Thus, the segment electrodes X ₁ to X ₄₀ are sequentially scanned. That is, the second scanning mode is, in short, a mode of sequentially scanning the electrodes.

In order to realize the first or second scanning mode as described above, the control circuit 19 controls the data latch circuit 15, the line latch circuit 16, the shift register 17 and the level shifter 18 as follows.

That is, the level of the mode signal mode input to the control circuit 19 becomes "L", and the level of the scanning mode signal scan becomes "H". Then,
First, the data latch circuit 15 is controlled according to the clock signal cp2o input to the clock input terminal XCK and the clock signal cp1o input to the latch pulse input terminal XLP, and the display data for one line is displayed as described above. It is taken in and sent to the line latch circuit 16. At the same time, the line latch circuit 16 is controlled so that the display data for one line is latched and sent to the level shifter 18.

After that, the level shifter 18 is controlled as follows according to the clock signal cp1o. That is, if the level of the AC signal fo input to the AC signal input terminal XFR is "H", and if the level of each display data from the line latch circuit 16 is "H", analog switch control is performed. While the signal s ₁ is output, if the level of each display data is “L”, the analog switch control signal s ₂ is output. Thus, the display voltage V ₀ or the non-display voltage V ₂ is applied to each segment electrode X according to the display data D ₀ o to D ₃ o.

On the other hand, when the level of the alternating signal fo is "L", as described above, when the level of the display data is "H", the analog switch control signal s ₄ is output. On the other hand, if the level of the display data is "L", the analog switch control signal s ₃ is output. Thus
A display voltage V ₅ or a non-display voltage V ₃ is applied to each segment electrode X according to the display data D ₀ o to D ₃ o.

In this way, the above display mode is implemented.

On the other hand, the level of the mode signal mode input to the control circuit 19 becomes "H" and the level of the scanning mode signal scan becomes "L". Then,
First, the shift register 17 is controlled according to the clock signal cp1o input to the latch pulse input terminal XLP, the pulse position of the shift data so is shifted as described above, and the shift data so in all the registers is sent to the level shifter 18. To be done.

After that, the level shifter 18 is controlled according to the clock signal cp1o, and according to the level of the alternating signal fro input to the alternating signal input terminal XFR, according to the contents of the shift data so as described above. The analog switch control signals s ₄ and s ₅ are output. If the content of the shift data so is "H", the corresponding segment electrode X
Is read out and output to the segment electrode voltage reading terminal H5. Also, the content of the shift data so is "L".
If so, the non-scanning voltage V ₅ is applied. Thus, the coordinate detection mode is carried out.

The above description of the electrode drive circuit has been made by taking the case where the present electrode drive circuit is used as the segment drive circuit 3 as an example. However, actually, the electrode drive circuit is also used as the common drive circuit 2. However, in that case, the level of the input to the control terminal S / C must be constantly set to "L" to fix the scanning mode to the second scanning mode. The application of the electrode drive circuit is selected by a combination of the mode signal mode and the scan mode signal scan. Therefore, Table 1 collectively shows the applications selected by the combination of the mode signal mode and the scanning mode signal scan, the analog switches selected in the applications, and the corresponding terminals.

[Table 1]

During the coordinate detection period, the alternating signal fro is generated.
Since the same analog switch is selected regardless of the level of, the description of the level of the alternating signal fro in the coordinate detection column of Table 1 is omitted.

The display-integrated type tablet device having the above-described configuration operates as follows to display an image on the pixel matrix and detect the tip coordinates of the electronic pen 11. FIG. 3 shows the electronic pen 1 in which a high frequency voltage is applied by scanning the display period in which an image is displayed in the pixel matrix of the liquid crystal panel 1 and the segment electrodes X and the common electrodes Y of the liquid crystal panel 1.
4 is a timing chart with a coordinate detection period in which the tip position of No. 1 is detected. In this display-integrated tablet device, one frame period is formed by the display period and the coordinate detection period. Also, the coordinate detection period can be set to x
It is formed by the coordinate detection period and the y coordinate detection period. By doing so, the display of an image on the pixel matrix of the liquid crystal panel 1 and the detection of the tip coordinates of the electronic pen 11 by the electrostatic induction tablet which is the liquid crystal panel 1 can be performed without impairing the performance of the other party. .

In FIG. 3, the coordinate detection period is shown to be considerably long for the sake of clarity, but in practice, the display period length / coordinate detection period length is set to "10" or more. Regarding the switching between the display period and the coordinate detection period, the switching circuit 7 is switched between the display control circuit 4 side and the detection control circuit 6 side based on the control of the control circuit 10, and the common drive circuit 2 and the segment drive circuit 3 are performed. This is carried out by switching the operation mode of.

In the display period, the control circuit 1 is
When the level of the mode signal mode from 0 becomes "L" and the level of the scanning mode signal scan becomes "H", the input level to the control terminal S / C of the common drive circuit 2 is fixed at "L". Thus, the operation modes of the common drive circuit 2 and the segment drive circuit 3 are set to the display mode. Further, the switching circuit 7 selects the shift data s, the AC signal fr, the clock signal cp1, and the clock signal cp2 from the display control circuit 4 based on the control of the control circuit 10, and shifts the shift data s.
o, AC signal fro, clock signal cp1o, clock signal cp2o
Output as.

Then, the common drive circuit 2 and the segment drive circuit 3 operate as described with reference to FIG. 2 and, for example, the common electrode drive signals a to h and the segment electrode drive signals A and B as shown in FIG. Is output. As a result, each pixel of the pixel matrix of the liquid crystal panel 1 is displayed as shown in FIG.

Next, during the coordinate detection period, the level of the mode signal mode from the control circuit 10 becomes "H" and the level of the scanning mode signal scan becomes "L". And
The operation mode of the common drive circuit 2 and the segment drive circuit 3 is set to the coordinate detection mode. Further, the switching circuit 7 controls the detection control circuit 6 based on the control of the control circuit 10.
Shift data from sd, alternating signal frd, clock signal cp1
d, the clock signal cp2d is selected and output as the shift data ao, the alternating signal fro, the clock signal cp1o, and the clock signal cp2o.

Then, the common drive circuit 2 and the segment drive circuit 3 operate as described with reference to FIG. 2, and the common electrode group or the segment electrodes are operated at the common electrode scanning timing or the segment electrode scanning timing as shown in FIG. Scan groups. In FIG. 4, the scanning time Tp in the segment electrode scanning and the common electrode scanning is set to be larger than the pulse width of the clock signal cp1o so that a plurality of adjacent segment electrodes X are simultaneously scanned. .

At this time, in the segment drive circuit 3, the analog switch Tr ₅ (see FIG. 2) corresponding to the segment electrode X to be scanned is turned on as described above, and the segment to be scanned is The voltage of the electrode X is read. Then, this detection voltage is input from the segment electrode voltage read terminal H5 to the x coordinate detection circuit 8 via the operational amplifier 14. Similarly, in the common drive circuit 2 as well, the voltage of the common electrode Y to be scanned is detected, and the y-coordinate detection circuit 9 is output from the common electrode voltage read terminal G5 via the operational amplifier 13.
Entered in.

Here, a high frequency voltage of a predetermined frequency is applied to the tip electrode of the electronic pen 11 by the high frequency power source 12. Therefore, when the tip of the electronic pen 11 is brought close to the surface of the liquid crystal panel 1, a voltage is induced in the segment electrode X due to the capacitance between the tip electrode of the electronic pen 11 and the segment electrode X. Therefore, as described above, the voltage of each segment electrode X is detected by the operational amplifier 14 while scanning the segment electrode group by the segment drive circuit 3, and as shown in FIG. It is possible to detect the induced voltage which becomes a peak when the segment electrode X immediately below is scanned.

The induced voltage signal relating to the segment electrode group thus obtained is shaped into a waveform as shown in FIG. 25 (b) and input to the x-coordinate detection circuit 8. Then, the electrostatic induction tablet 1 shown in FIG.
Similarly to the case of the x-coordinate detection circuit 107 in 01, the x-coordinate of the tip of the electronic pen 11 is obtained based on the input induced voltage and the x-coordinate signal is output.

Similarly, the common drive circuit 2
And the operational amplifier 13 detects the induced voltage signal related to the common electrode group, and the y coordinate detection circuit 9 outputs the y coordinate signal based on the obtained induced voltage related to the common electrode group.

The x-coordinate signal and the y-coordinate signal thus output are processed by the CPU (central processing unit) as necessary and then input to the display control circuit 4 to be converted into display data D _{0 to} D _3. . Therefore, in the display period, the display data D _{0 to} D ₃ representing the tip coordinates of the electronic pen 11 are displayed.
If an image based on is displayed on the liquid crystal panel 1, the image can be input by the electronic pen 11 as if writing on paper with a writing instrument.

As described above, in this embodiment, the detection control is performed in the duty type liquid crystal display device which is roughly composed of the liquid crystal panel 1, the common drive circuit 2, the segment drive circuit 3, the display control circuit 4 and the power supply circuit 5. A circuit 6, a switching circuit 7, an x coordinate detection circuit 8, ay coordinate detection circuit 9, a control circuit 10 and an electronic pen 11 are added. The display period for displaying an image in the pixel matrix of the liquid crystal panel 1 and the electronic pen 1 on the liquid crystal panel 1 are set for each frame period.
It is arranged to be time-divided into a coordinate detection period for detecting the leading edge coordinate of 1.

In the display period, the control circuit 1 is
By the control of 0, the common drive circuit 2 and the segment drive circuit 3 are set to the display mode, while the switching circuit 7 selects the display control circuit 4 side. Then, in accordance with the shift data so, the alternating signal fro, the clock signal cp1o and the clock signal cp2o output from the switching circuit 7 based on the selected signal from the display control circuit 4, the common drive circuit 2 and the segment drive circuit 3 Works.
At that time, the common electrode drive signals a to h generated by the common drive circuit 2 are transferred to the common electrodes Y ₁ to Y of the liquid crystal panel 1.
Is input to Y _8, display columns of the pixel matrix of the liquid crystal panel 1 are sequentially selected. On the other hand, the segment drive circuit 3
The segment electrode drive signals A and B generated based on the display data D ₀ o to D ₃ o are input to the segment electrodes X _{1 to} X ₄₀ of the liquid crystal panel 1 and selected by the common drive circuit 2 in the pixel matrix. The pixels in the displayed display column are displayed according to the display data. Thus
The pixel matrix is displayed as shown in FIG.

During the coordinate detection period, the common drive circuit 2 and the segment drive circuit 3 are set to the coordinate detection mode under the control of the control circuit 10, while the switching circuit 7 selects the detection control circuit 6 side. Then, based on the signal from the selected detection control circuit 6, the shift data so output from the switching circuit 7 and the alternating signal f
The common drive circuit 2 and the segment drive circuit 3 operate according to ro, the clock signal cp1o, and the clock signal cp2o. In this way, the segment drive circuit 3 sequentially scans the segment electrodes X, and the voltage of the segment electrode X to be scanned is detected. And the electronic pen 11
The induced voltage induced in the segment electrode X due to the high frequency voltage applied to the tip electrode of the electronic pen 11 is detected, and the x coordinate of the tip of the electronic pen 11 is detected by the x coordinate detection circuit 8 based on this induced voltage. The x coordinate signal is output. Subsequently, the common drive circuit 2 scans the common electrode Y to detect the induced voltage of the common electrode Y to be scanned. Then, based on the detected induced voltage of the common electrode Y, the y-coordinate detection circuit 9 detects the y-coordinate of the tip of the electronic pen 11 and outputs the y-coordinate signal.

At this time, since the potential difference between the segment electrode X and the common electrode Y is set to be smaller than the threshold value of the liquid crystal display voltage in the coordinate detection period, the pixel matrix of the liquid crystal panel 1 in the coordinate detection period. Is not displayed. The x coordinate signal and y thus output
The coordinate signals are displayed by the display control circuit 4 as display data D _{0 to} D _3.
It is converted to the display data D _o o~D _{3 o} outputted from the switching circuit 7 in accordance with the display data D ₀ to D _3, which is the converted
Based on, the pixel at the tip position of the electronic pen 11 on the pixel matrix of the liquid crystal panel 1 is displayed.

As described above, each frame period in the pixel matrix display of the liquid crystal panel 1 is time-divided into the display period and the coordinate detection period. The liquid crystal panel 1 is used as an image display unit during the display period, while the liquid crystal panel 1 is used as a tablet during the coordinate detection period to form a tablet having an integrated display function.

Therefore, according to the present embodiment, the low light transmittance of the row / column electrodes of the tablet lowers the brightness and contrast of the display screen of the display unit, the regularity of the electrode arrangement of the tablet, the display unit and the tablet unit. It is possible to solve problems such as a reduction in the visibility of the display unit due to the shift of the corresponding portions, and an increase in size and cost due to stacking the tablet and the display unit. That is, the display-integrated tablet of the present embodiment is easy to see the display screen when the position on the display screen is input by the pen, and it is easy to reduce the size and cost.

Further, in the above-described embodiment, the electrode drive circuit constituting the common drive circuit 2 or the segment drive circuit 3 has the bidirectional analog switch circuit composed of the analog switches Tr _{1 to} Tr _5, so that the bidirectional It is possible to easily perform voltage supply to each electrode and voltage reading from each electrode via the analog switch circuit.

In the common drive circuit 2 and the segment drive circuit 3 in the above embodiment, the induced voltage is directly taken out from the common electrode voltage read terminals G5 and H5. However, if an operational amplifier is provided between the analog switch Tr ₅ and the electrode voltage read terminals G 5, H ₅ to increase the input impedance viewed from the analog switch Tr ₅ side and decrease the output impedance, the operational amplifier in FIG. The amplifiers 13 and 14 are not necessary, and the induced noise on the wiring can be reduced, which is preferable.

In the above embodiment, the number of common electrodes Y is 8 and the number of segment electrodes X is 40 in order to simplify the description, but normally both electrodes are several hundreds. In that case, the LSIs forming the electrode driving circuit as shown in FIG. 2 may be connected in a cascade.

In the above embodiment, one set of the electronic pen 11, the operational amplifiers 13 and 14, the x coordinate detecting circuit 8 and the y coordinate detecting circuit 9 is provided.
However, the present invention is not limited to this. The electronic pen 11 and the operational amplifier 13
14, a plurality of sets of the x-coordinate detection circuit 8 and the y-coordinate detection circuit 9 are provided, and the frequency of the high-frequency voltage to each set of electronic pens is changed to enable independent pen input by a plurality of electronic pens. It doesn't matter. At that time, if the characters and figures entered by each electronic pen are displayed in different line types (for example, solid line, dotted line, thick line, etc.) and different colors, the characters drawn by different electronic pens will be displayed. And shapes can be easily distinguished.

Further, in the above-mentioned embodiment, by adding the recognition means for the input character or figure, the character or figure inputted by the pen is recognized by the recognition means, and various kinds of processing are executed by using the recognition result. It is also possible to do so.
Alternatively, by adding an instruction judging means, the contents of the processing menu instructed by the electronic pen among various processing menus (so-called icons) displayed on the liquid crystal panel 1 are judged, and the processing according to the judgment result is executed. It is also possible to do so. Furthermore, if a polymer-dispersed liquid crystal is used as the liquid crystal used in the liquid crystal panel 1, a flexible sheet-like tablet can be formed, and a notebook computer can be realized.

[Second Embodiment] FIG. 5 is a block diagram of a display-integrated type tablet device different from that of FIG. Incidentally, FIG.
Elements that are exactly the same as those in FIG.
The common drive circuit 2 in the display-integrated type tablet device in the present embodiment is not provided with the mode signal input terminal MODE and the common electrode voltage reading terminal G5.
Further, the segment drive circuit 3 has a mode signal input terminal MODE and a segment electrode voltage read-out terminal H.
5 is not provided.

A bidirectional analog switch 21 is provided on the line for supplying the bias power supply V ₅ from the power supply circuit 5 to the input terminal V 5 of the common drive circuit 2. The input terminal of the operational amplifier 13 is connected to the other terminal of the analog switch 21. Thus, by switching the analog switches 21, so that the input terminal V5 of the common drive circuit 2 is connected is switched to the supply line side of the bias power supply V ₅ of the operational amplifier 13 side and the power supply circuit 5. Furthermore, the line for supplying the bias power source V ₅ to the input terminal V5 of the segment driving circuit 3 from the power supply circuit 5 interposed bidirectional analog switch 22. The input terminal of the operational amplifier 14 is connected to the other terminal of the analog switch 22. In this way, by switching the analog switch 22, the input terminal V5 of the segment drive circuit 3 is changed to the operational amplifier 1
4 and the supply line side of the bias power supply V ₅ of the power supply circuit 5 are switched and connected.

The common drive circuit 2 in this embodiment is shown in FIG.
It has the same structure as the common electrode 2'shown in FIG. However, the shift data so and the clock signal cp1o are input to the shift register 35, while the alternating signal fro is input to the level shifter 36.

The pulse position of the shift data so input to the shift data input terminal DIO1 is the clock signal cp1o.
And the shift data so fetched in all the built-in registers are shifted in synchronization with the level shifter 36.
Are output in parallel. Then, the level shifter 36
Is _{one of the} analog switch control signals s _{1 to} s ₄ depending on the level of the alternating signal fro input from the alternating signal input terminal YFR and the level of each shift data so input from the shift register 35. One of the outputs is "on" the analog switch Tr ₁ to Tr ₄ to the corresponding. In this way, the bias power supplies V _{0 to} V ₅ selected by the analog switches Tr _{1 to} Tr ₄ are output to the corresponding common electrodes Y. Thus, only sequential scanning is performed.

FIG. 6 is a detailed block diagram of the segment drive circuit 3 in this embodiment. In the segment drive circuit 3 of this embodiment, the mode signal input terminal MODE, the segment electrode read terminal H5 and the analog switch Tr in the segment drive circuit 3 shown in FIG. 2 are used.
Not equipped with ₅ .

When the scanning mode signal scan of level "H" is input to the control circuit 29, the control circuit 2
9, data latch circuit 25, line latch circuit 2
6 and the level shifter 28 are controlled to implement the first scanning mode. The first scanning mode is a mode in which the segment electrodes X are collectively scanned during the display period. On the other hand, when the level "L" scan mode signal scan is input to the control circuit 29, the control circuit 29 controls the shift register 27 and the level shifter 28 to implement the second scan mode. The second scanning mode is a mode in which the segment electrodes X are sequentially scanned during the coordinate detection period.

The display-integrated type tablet device having the above-described configuration operates as follows. First, in the above display period, the level of the scan mode signal scan from the control circuit 10 is "H".
Then, since the input level of the control terminal S / C of the common drive circuit 2 is fixed to "L", the common drive circuit 2
The scanning mode of 1 is set to the second scanning mode (sequential scanning), while the scanning mode of the segment drive circuit 3 is set to the first scanning mode (collective scanning). Then, the common drive circuit 2 and the segment drive circuit 3 operate similarly to the display mode in the first embodiment, and the display operation is performed.

Next, in the coordinate detection period, the level of the scan mode signal scan from the control circuit 10 becomes "L", and the scan modes of the common drive circuit 2 and the segment drive circuit 3 are the second scan mode ( Sequential scanning) is set. Then, the common drive circuit 2 and the segment drive circuit 3 operate in the same manner as in the coordinate detection mode in the first embodiment to turn on the analog switch Tr ₄ corresponding to the scan target segment electrode X or the scan target common electrode Y. By setting to ", the common electrode group or the segment electrode group is scanned.

At this time, the analog switches 21 and 22 are switched to the operational amplifier 13 side or the operational amplifier 14 side by the control signal from the control circuit 10, and the bias power source V5 from the power source circuit 5 is driven in common. It is designed not to be supplied to the circuit 2 and the segment drive circuit 3. Therefore, in the coordinate detection mode, the voltage of the segment electrode X to be scanned is output to the operational amplifier 13 via the analog switch 21. On the other hand, the voltage of the common electrode Y to be scanned is output to the operational amplifier 14 via the analog switch 22.

Since a high frequency voltage having a predetermined frequency is applied to the tip electrode of the electronic pen 11 by the high frequency power source 12, the segment electrode X and the common electrode Y are used.
A voltage is induced at. Therefore, when the voltages of the individual electrodes of the common electrode group and the segment electrode group are detected by the common drive circuit 2 and the segment drive circuit 3 as described above, the electrodes directly below the electronic pen 11 as shown in FIG. The induced voltage which becomes a peak at the time of scanning is detected.

The coordinates of the tip of the electronic pen 11 are obtained in the same manner as in the first embodiment based on the induced voltage signals related to the segment electrode group or the common electrode group thus obtained, and the x coordinate signal and the y coordinate are obtained. The signal is output.

FIG. 7 shows the segment drive circuit 3 shown in FIG.
6 is a block diagram of a segment drive circuit 3 having a different configuration from FIG. In the segment drive circuit 3 shown in FIG. 6, among the four types of bias voltages V ₀ , V ₂ , V ₃ , V ₅ input to the input terminals V0, V2, V3, V5, the level of the alternating signal fro is The set of bias voltages selected when “H” is (V ₀ , V ₂ ), and the set of bias voltages selected when the level of the alternating signal fro is “L” (V ₃ , V ₅ ) only.

Therefore, the segment drive circuit 3 shown in FIG.
In the above, analog switches 30 and 31 that switch according to the level change of the alternating signal fro are provided, and bias voltages V ₀ and V ₅ that are not selected at the same time are input to the switching terminals of the analog switch 30. Bias voltages V ₂ and V ₃ that are not selected at the same time are input to the switching terminal of the switch 31. Then, according to the level of the alternating signal fro in advance, the analog switch 3
0, 31 are switched to select either the bias voltage pair (V ₀ , V ₂ ) or the bias voltage pair (V ₃ , V ₅ ) and set the respective elements to the analog switch Tr ₁ or the analog switch Tr. ₂ , and one of the bias voltage sets is selected by controlling the analog switches Tr ₁ and Tr ₂ according to the output data of the level shifter 28.

By doing so, the number of analog switches can be reduced and the structure of the level shifter 28 can be simplified.

In the display-integrated type tablet device shown in FIG. 5, the analog switches 21 and 22 and the operational amplifiers 13 and 14 are provided outside the common drive circuit 2 or the segment drive circuit 3. However, the present invention is not limited to this. For example, in FIG.
By incorporating it in the electrode driving circuit shown in FIGS. 1, 6 and 7, external noise can be reduced and the display-integrated type tablet device can be simplified.

[Third Embodiment] FIG. 8 is a timing chart of scanning the segment electrodes X and the common electrodes Y at timings different from the timings of the segment electrode scanning and the common electrode scanning shown in FIG. In this case, the scanning timing is such that a plurality of segment electrodes X or a plurality of common electrodes Y are collectively scanned.

That is, in FIG. 8, in the segment drive circuit 3, a segment electrodes X ₁ , X ₂ ,
..., _Xa are scanned collectively. Next, the a segment electrodes X _{a + 1} , X _{a + 2} , ..., X _2a are collectively scanned. Similarly, a segment electrodes _{Xm-a + 1} , ..., _Xm are collectively scanned. On the other hand, in the common drive circuit 2, the b common electrodes Y ₁ , Y ₂ , ..., Y _b are collectively scanned. Next, the b common electrodes Y _{b + 1} , Y _{b + 2} , ...,
X _2b is scanned collectively. Similarly, the b common electrodes Y _{n-b + 1} , ..., X _n are collectively scanned.

In this way, by scanning the a segment electrodes X and the b common electrodes Y together, the clock signal cp1d and the clock signal cp2d output from the detection control circuit 6 are provided for each electrode one by one. The scanning speed of the segment electrode X is a times the scanning speed of the common electrode Y and the scanning speed of the common electrode Y is b times even if the signal has the same period as in the case of scanning. Therefore, the coordinate detection period can be shortened to secure a sufficient display period, and the display of the high-density liquid crystal panel can be sufficiently dealt with.

Further, as shown in FIG. 4 or FIG. 8, simultaneous scanning of a plurality of segment electrodes X and a plurality of common electrodes Y is important in carrying out each of the above embodiments. is there. In order to scan a plurality of segment electrodes X and common electrodes Y in the present invention,
There are two reasons:

First Reason At the time of coordinate detection in the display-integrated type tablet device shown in FIG. 1 or 5, when the high frequency voltage of a predetermined frequency is applied from the high frequency power source 12 to the tip electrode of the electronic pen 11, the segment electrode X and The induced voltage induced in the common electrode Y is detected by scanning the segment electrode group and the common electrode group. Therefore, in order to detect the tip coordinates of the electronic pen 11 with high accuracy, the time (scanning time) during which one segment electrode X or the common electrode Y is scanned is set to the high frequency voltage applied to the tip electrode of the electronic pen 11. It must be set longer than the cycle.

For example, if the tip electrode of the electronic pen 11 is 200
When a high frequency voltage of kHz is applied, the cycle is 5μ
Since it is sec, each segment electrode X and common electrode Y
The scanning time is required to be 5 μsec or more. Therefore, when the number of pixels of the liquid crystal panel 1 is 640 × 480,
When each of the electrodes X and Y is scanned one by one, the time required to scan all the segment electrodes and the common electrode is (640 + 480) × 5 μsec / line = 5600 μsec = 5.
It reaches 6 msec.

This scanning time "5.6 μsec" is a time that does not cause any problem in the case of the electrostatic induction tablet single function. However, in the case where one frame is operated by time division into the display period and the coordinate detection period as in the display-integrated type tablet device, if the frame frequency is 60 Hz, the frame period is about 16.7 msec. The ratio of the period reaches 33.5%. Therefore, the time that can be used for image display in one frame period is (16.7-
5.6) = 11.1 msec, which is a practical problem because the image quality of the display screen is significantly deteriorated. As a countermeasure, the frequency of the high frequency voltage applied to the tip electrode of the electronic pen 11 may be increased. However, there is a limit in increasing the frequency of the high frequency voltage for the following reasons.

[0155] Figure 9 is an equivalent circuit of the distributed capacitance C between the n-th distributed resistances r and n th common electrode in the common electrode Y _n of the Y _n and the segment electrodes X opposing thereto. From the figure, segment electrode X and common electrode Y
It can be seen that forms a low-pass filter composed of r and C. The distributed resistance r and the distributed capacitance C are the resistance and the electrostatic capacitance per pixel, and their values differ depending on the material of the liquid crystal or the segment electrode X or the common electrode Y, but r is about 20Ω and C is 1 pF. It is a degree.

On the other hand, the number of pixels in the x direction is 640 in the case of a standard liquid crystal panel. Therefore, as shown in FIG. 9, the electronic pen 11 is separated from the common drive circuit 2.
When located at the right side in the figure, the voltage induced by the electrostatic capacitance C _p between the tip electrode of the electronic pen 11 and the common Y is attenuated by r · C and is reduced by the common drive circuit 2 Entered in. Moreover, the higher the frequency of the high-frequency voltage from the high-frequency power source 12, the greater the amount of attenuation, and in extreme cases, the amount of attenuation is undetectable. That is, even if the electronic pen 11 is located on the side opposite to the common drive circuit, the frequency of the high frequency voltage in the high frequency power source 12 cannot be increased in order to maintain the level of the induced voltage induced in the common electrode Y at a high level. .

Second Reason Generally, the electrode width of the segment electrode X and the common electrode Y which compose the liquid crystal panel 1 is about 0.3 mm. However, in recent years, there is a tendency to further reduce the electrode width for finer display. Making the electrode width narrow means that the capacitance between the tip electrode of the electronic pen 11 and the segment electrode X or the common electrode Y becomes small,
As a result, the induced voltage induced in the segment electrode X or the common electrode Y also becomes low. Therefore, the electronic pen 11
Therefore, the detection accuracy of the tip coordinates becomes low.

For the above two reasons, the plurality of segment electrodes X and the plurality of common electrodes Y are simultaneously scanned as shown in FIG. 4 or FIG. For example, when scanning 640 segments X and 480 common electrodes Y by 16 lines at a scanning speed of 5 μsec / line, the scanning period is (640 lines × 480 lines) × 5 μsec / 16 = 350 μsec. Therefore, the ratio of the detection period to one frame period (16.7 msec) is about 2%, and the display period is 98%.
%, The influence on the display quality can be ignored. Along with this, the value of the induced voltage induced in the segment electrode X and the common electrode Y also increases by about one digit.

As described above, it seems that scanning a plurality of electrodes at the same time significantly lowers the detection accuracy, but it has been confirmed that there is no problem in practice. In particular, it is more preferable to sequentially scan one electrode with a delay of one clock as shown in FIG. 4 because a higher detection accuracy can be obtained. However, as shown in FIG. 8, even when a plurality of electrodes are collectively scanned, the rise time Tr of the detection pulse as shown in FIG. 25C obtained from the waveform of FIG. From the fall time Tg, the electronic pen 11
It is possible to obtain detection accuracy that can withstand practical use by obtaining the tip coordinates of.

A technique for enabling the display-integrated type tablet device as shown in FIGS. 1 and 5 to fully exhibit its functions will be described below. [Fourth Embodiment] In the coordinate detection period in each of the above embodiments, the tip coordinates of the electronic pen 11 are detected by using the capacitance between the tip electrode of the electronic pen 11 and the segment electrode X and the common electrode Y. I am trying to do it. Therefore, of the segment electrode X and the common electrode Y, the induced voltage induced in the upper electrode (segment electrode X in FIGS. 1 and 5) directly facing the electronic pen 11 is induced in the lower electrode. Higher than the induced voltage. The ratio of these two induced voltages is usually about 1/20 although it depends on the structures and shapes of the liquid crystal panel 1 and the electronic pen 11. Therefore, some measure is required to detect the coordinate detected by the upper electrode and the coordinate detected by the lower electrode with the same accuracy.

First Response As described above, since the levels of the induced voltage of the upper electrode and the induced voltage of the lower electrode are different, the operational voltage connected to the electrode voltage read terminal of the upper electrode
By changing the amplification factors of the amplifier and the operational amplifier connected to the electrode voltage reading terminal of the lower electrode, the same level of induced voltage is obtained. For example, in the liquid crystal panel 1 shown in FIGS. 1 and 5, the common electrode Y
Is located below the segment electrode X. Therefore, the amplification factor of the operational amplifier 13 is set higher than that of the operational amplifier 14. The x-coordinate detection circuit 8 and the y-coordinate detection circuit 9
In the case where the coordinate detection is performed by the binarized waveform as shown in FIG. 25C, the same effect can be obtained by changing the reference voltage (slice voltage) when binarizing.

Second Response As described above, the segment electrode X and the common electrode Y are used.
When scanning a plurality of lines simultaneously, the number of scans of the lower electrode is set to be larger than the number of scans of the upper electrode. By doing so, the induced voltage induced in the lower electrode is made higher than the induced voltage induced in the upper electrode.

Third Correspondence As shown in FIG. 3, the coordinate detection period is defined as x coordinate detection period and y.
When the upper electrode and the lower electrode are scanned at different times by time division into the coordinate detection period, the high frequency voltage value applied to the tip electrode of the electronic pen 11 during the scanning period of the lower electrode is set to the upper side. It is set higher than the high frequency voltage value applied during the scanning period of the electrodes. In this way, the induced voltage induced in the lower electrode is made higher than the induced voltage induced in the upper electrode.

Fourth Correspondence The electrode interval of the lower electrode is made narrower than the electrode interval of the upper electrode to make the capacitance between the lower electrode and the electronic pen 11 dense. For example, in the case of the display-integrated type tablet device shown in FIG. 1 or 5, the segment electrode X which is the upper electrode.
Is 50 μm, while the common electrode Y, which is the lower electrode, is 30 μm, and the induced voltage to the common electrode Y is increased.

[Fifth Embodiment] By giving the liquid crystal panel 1 a tablet function, it is absolutely necessary to avoid deterioration of the liquid crystal of the liquid crystal panel 1. The deterioration of the liquid crystal is caused by the segment electrode X and the common electrode Y sandwiching the liquid crystal.
It occurs when a DC voltage is applied between and. Therefore,
During the display period, as described above, the alternating voltage signal fro is used to reverse the direction of voltage application to the liquid crystal every predetermined number of lines (for example, 13 lines) so that the average voltage applied to the liquid crystal becomes "0". There is.

Therefore, it is desirable that the average voltage applied to the liquid crystal is "0" even in the coordinate detection period. Therefore, the voltage of the non-scanning segment electrode and the non-scanning common electrode are made the same. This method is the most reliable and simple method. The non-scanning voltage may be a DC voltage, and any one of the bias voltages V _{0 to} V ₅ may be selected. When the voltage of the non-scanning segment electrode and the voltage of the non-scanning common electrode cannot be the same due to the entanglement with the display voltage or the non-display voltage in the display period,
Connect an analog switch or the like to any of the input terminals V0 to V5 of the common drive circuit 2 or the segment drive circuit 3,
The bias voltage is selected so that the voltage of the non-scanning segment electrode and the voltage of the non-scanning common electrode can be made the same by switching the analog switch in the display period and the coordinate detection period.

It is desirable that the voltage of the scanning electrode and the voltage of the non-scanning electrode in the segment electrode X and the common electrode Y are the same. Therefore, as shown in FIG. 1 or FIG. 5, the power supplies V ₆ and V ₇ are connected to the input sides of the operational amplifier 13 and the operational amplifier 14 via a high resistance, and the same voltage as the non-scan voltage is applied to the scan electrodes. To supply. In this case, since the induced voltage from the electrode voltage read terminals G5 and H5 is an AC voltage and is a low voltage, there is no problem at all.

[Sixth Embodiment] During x coordinate detection period and y
During the coordinate detection period, it is desirable to fix the level of the alternating signal fro to "H" or "L" for the following reason. That is, in the display-integrated type tablet device shown in FIG. 5, the analog switch 2 is used in the coordinate detection mode.
1, 22 are switched to read the voltages from the input terminals V5, V5 and output them to the operational amplifiers 13, 14. However, as seen in FIGS. 6, 7, and 11, the input terminals V0 to V5 are connected to the alternating signal fro.
Analog switches Tr _{1 to} Tr ₄ , 30, 3 depending on the level of
Switching selection is made by 1. Therefore, when the level of the alternating signal fro changes during the x coordinate detection period or the y coordinate detection period, the order of electrodes for reading the voltage to the operational amplifiers 13 and 14 differs from the shift order of the shift registers 27 and 35. Therefore, the coordinates of the tip of the electronic pen 11 cannot be detected.

In FIG. 3, the combination of the level of the alternating signal fro during the x-coordinate detection period and the level of the alternating signal fro during the y-coordinate detection period is L-L, but H-H, H-L, It may be a combination of L-H. It goes without saying that the input terminals V0 to V5 to which the analog switches 21 and 22 in FIG. 5 are connected need to be set according to the above combination.

Further, in each of the above embodiments, as shown in FIG. 3, the alternating signal fro (hereinafter referred to as the display alternating signal) output from the switching circuit 7 based on the alternating signal fr from the display control circuit 4. , And the AC signal frd output from the switching circuit 7 based on the AC signal frd from the detection control circuit 6 (however, as described above, x
The level is constant during the coordinate detection period and the y coordinate detection period: hereinafter referred to as a detection alternating signal). However, if the detection AC signal is simply inserted into the display AC signal, unevenness occurs in the inversion cycle of the voltage direction applied to the liquid crystal during the display period, and "ripple display unevenness" appears on the display screen. Not preferable.

Therefore, as shown in FIG. 3, when the detection AC signal is inserted at the time when the level "H" of the display AC signal has passed the time t _f , the display period of the next frame is started. and "H" level of the display switching signal at the time, the time _{t b t b = T f -t} f However, T _f: is to reverse the cycle of the display alternating signal. This can be realized by setting the inversion period T _f of the display alternating signal by counting a predetermined number of clocks of the clock signal cp1o to the common drive circuit 2 in the display period. For example, a good display result can be obtained by setting the count number to "13".

The above is a description of the display-integrated tablet device having the liquid crystal panel 1 driven by the duty type driving method.

<Second Example> Next, a display-integrated type tablet device in which an active matrix type liquid crystal panel is integrally provided with a tablet function will be described. Although there are various types of liquid crystal panels of the active matrix type, the liquid crystal panel of the thin film transistor (TFT) type will be described below as an example. However, in the following explanation,
The same elements as those of the display-integrated type tablet device by the drive system of the duty type shown in FIGS. 1 and 5 are designated by the same reference numerals, and the description thereof will be omitted.

[Seventh Embodiment] FIG. 15 is a partial sectional view showing the structure of a liquid crystal panel of the TFT type.
Liquid crystal panel by T method (hereinafter simply referred to as liquid crystal panel)
51 has two glass substrates 52 and 53 facing each other.
Then, on the glass substrate 52, a TFT which is an active element is formed.
54, a pixel electrode 55 connected to the drain electrode of the TFT 54, an auxiliary capacitance electrode (not shown), a gate bus line electrode 56 as a Y electrode, a source bus line electrode 57 as an X electrode, and the like.

On the other hand, a transparent counter electrode 58 is formed on the glass substrate 53, and in the case of color display, R is used.
A GB color filter 59 is formed. And
The glass substrate 53 and the glass substrate 52 are opposed to each other with a space of several μm facing each other with the laminated film forming surface facing inward, and liquid crystal is filled between them.

When the liquid crystal panel 51 having the above-mentioned structure is used as a liquid crystal panel for a display-integrated type tablet device, as shown in FIG. 15, electronic devices are provided on the glass substrate 52 side on the TFT 54 forming side through a protective plate 60. Position the pen 11. As a result, the observer looks at the liquid crystal panel 51 from the opposite direction to the case of the liquid crystal panel having only the normal display function. This is for the following reason. That is, when the liquid crystal panel 51 is viewed from the glass substrate 53 side as in the conventional case, a transparent conductor of about 20Ω / □ is provided between the tip electrode of the electronic pen 11 and the source bus line electrode 57 or the gate bus line electrode 56. The counter electrode 58 formed in 1 above enters. Therefore, the tip electrode and the source bus line electrode 57 or the gate bus line electrode 56 are
Between the tip electrode and the source bus line electrode 57 or the gate bus line electrode 56 because they are electrostatically shielded from each other.
There is no electrostatic coupling between and. Therefore, the source bus line electrode 57 and the gate bus line electrode 5
No induction voltage due to the high frequency voltage applied to the tip electrode of the electronic pen 11 from the high frequency power source 12 is generated at 6.

Further, since the liquid crystal panel 51 does not emit light by itself, it is irradiated with light by a backlight arranged on the back side. A fluorescent lamp is often used as the backlight. In that case, since the electrostatic field and the external unnecessary field generated by the fluorescent lamp arranged behind the liquid crystal panel 51 and its lighting power source are shielded by the counter electrode 58, the source bus line electrode 57 and the gate bus line electrode. Invasion of electrostatic noise into 56 is prevented.

When the liquid crystal panel 51 is arranged as shown in FIG. 15, the irradiation light may act on the gate portion of the TFT 54 to make the operation of the TFT 54 unstable. Therefore, it is necessary to provide a light shielding means on the surface of the gate portion of the TFT 54 to prevent malfunction due to irradiation from the back side.

FIG. 16 is a block diagram of a main part of a display-integrated type tablet device using the liquid crystal panel 51 shown in FIG. 15. The control circuit 10, the display control circuit 4, the detection control circuit 6, and the switching circuit 7 (see FIG. 1 and FIG. (See FIG. 5) is omitted. The gate drive circuit 61 and the source drive circuit 62 are drive circuits of the liquid crystal panel 51 and also operate as detection circuits of the tip coordinates of the electronic pen 11.

The operation in the coordinate detection period in the display-integrated tablet device uses the gate bus line electrode 56 and the source bus line electrode 57 as detection electrodes, and uses the TFT 54 and the pixel electrode 55, which are active elements, in coordinate detection. The feature is that is not used.

That is, the voltage of the gate bus line electrode 56 in the coordinate detection period is the voltage of the input / output terminals G1 to Gn of the gate drive circuit 61 (hereinafter, any input / output terminal is referred to as G) and the electronic pen 11. And the induced voltage induced in the gate bus line electrode 56 due to the high frequency voltage applied to the tip electrode of the. Therefore, the sum of the voltage of the input / output terminal G and the peak value of the induced voltage is the TFT 54.
The output voltage of the high frequency power supply 12 and the bias power supply to the gate drive circuit 61 are set so as to be lower than the "ON" voltage of.

By holding the TFT 54 in the “off” state in this way, the voltage of the pixel electrode 55 connected to the drain electrode of the TFT 54 is held by the electrostatic capacity and the auxiliary capacity between the pixel electrode 55 and the counter electrode 58. Then, although it is slightly lowered by the leak current, it is almost maintained during the coordinate detection period. As a result, the display state in the display period is maintained until the display period in the next frame, and the influence on the display image quality can be ignored.

The operation of the display-integrated type tablet device having the above configuration will be described below. The above display period, all of the analog switches Ss ₁ ~ SS _n of the source driver circuit 62 is switched to the terminal a side. Then, the display data D ₀ o to D ₃ o fetched by the display data scanning circuit 63 correspond to the corresponding source bus line electrodes 57 from the input / output terminals S 1 to Sm.
Is output to. In this way, a voltage corresponding to the display data D ₀ o to D ₃ o is applied to the source electrode of the TFT 54.

On the other hand, on the side of the gate drive circuit 61, first, all the analog switches Sg _{1 to} Sg _n are simultaneously connected to the terminals b.
The voltage V _GOFF is output from the input / output terminals G _{1 to} G _n in order to turn off the TFT 54 by switching to the side. Next, under the control of the shift register 64, the analog switches Sg _{1 to} Sg _n are sequentially switched to the terminal a side for scanning, and the voltage V _GON for “turning on” the TFT 54 is output from the corresponding input / output terminal G. The TFT 54 is turned on by being applied to the gate electrode of the TFT 54 for one line. As a result, a voltage according to the display data D ₀ o to D ₃ o is applied to the pixel electrode 55 connected to the drain electrode of the TFT 54 related to the gate bus line electrode 56 connected to the corresponding input / output terminal G. It will be different. Thus, the pixels for one line are displayed.

Next, the coordinate detection period will be described. First, during the y-coordinate detection period, all the analog switches Sg _{1 to} Sg _n of the gate drive circuit 61 are switched to the terminal b side all at once, and all the TFTs 54 are turned off. Next, according to the output of the shift register 64, the analog switches Sg _{1 to} Sg _n are sequentially switched to the terminal c side and scanned. At this time, the number of electrodes to be simultaneously scanned is set to be plural for the reason described in the first example. In that case, each terminal c is connected to an operational amplifier 65 having a high input impedance, and the TFT 54 outputs the DC voltage of the gate bus line electrode 56 scanned by applying the voltage V _GOFF via a high resistance. Use a voltage that maintains the "off" state.

In this way, the gate drive circuit 61 sequentially scans the gate bus line electrodes 56, and the induced voltage induced by the high frequency voltage applied to the electronic pen 11 is sent to the operational amplifier 65.
Then, the y-coordinate detection circuit 66 obtains the y-coordinate of the tip of the electronic pen 11 in the same manner as in the first example, and outputs the y-coordinate signal.

Next, during the x-coordinate detection period, all the analog switches Sg _{1 to} Sg _{n of the} gate drive circuit 61 are switched to the terminal b side. Further, after all of the analog switches Ss ₁ ~ SS _m of the source drive circuit 62 is switched to the terminal b side, the analog switch Ss ₁ ~ SS _m are scanned switched sequentially to the terminal c side in accordance with the output of the shift register 67 It At that time, the number of scanning electrodes should be plural. In this way, the source driving circuit 62 sequentially scans the source bus line electrodes 57, and the electronic pen 11
The induced voltage induced due to the high frequency voltage applied to is transmitted to the x coordinate detection circuit 69 via the operational amplifier 68. Then, by the x-coordinate detection circuit 69, as in the case of the first example, the x-axis of the tip of the electronic pen 11 is
The coordinates are determined and the x coordinate signal is output.

Although the input impedances of the operational amplifiers 65 and 68 are set to high values, the same voltage as that of the counter electrode 58 is applied via a high resistance in order to prevent deterioration due to electrolysis of liquid crystal. To Further, in the above embodiment, the case where the x-coordinate detection period and the y-coordinate detection period are time-divided and serially processed is described. However, the present embodiment is not limited to this, and processing may be performed in parallel.

The gate bus line electrode 56 and the source bus line electrode 57 used for coordinate detection in this embodiment.
Has a width of about 0.03 mm, which is one digit smaller than the width of 0.3 mm of the segment electrode X and the common electrode Y in the liquid crystal panel 1 of the duty type driving method of the first example. Therefore, in the coordinate detection in this embodiment, it is the first to scan the plurality of gate bus line electrodes 56 and the plurality of source bus line electrodes 57 at the same time.
Needed more than the example. In this case, a plurality of main scans are performed by the shift data s input to the shift registers 64 and 67.
This can be easily realized by making the pulse width of o longer than the cycle of the transfer clock of the shift registers 64 and 67. However, the pulse of the shift data so may be composed of one pulse having a wide width, or may be composed of a plurality of adjacent pulse groups.

FIG. 17 is a block diagram of the main part of a gate drive circuit 75 different from the gate drive circuit 61 in FIG. The bidirectional analog switch 76 is switched to the power supply V _GON side in the display period as shown in the figure, and switched to the operational amplifier 65 side in the coordinate detection period. As a result, the bidirectional analog switch 77 sequentially outputs the output voltage V _GON for turning on the TFT 54 to the corresponding input / output terminal G based on the output of the shift register 78 during the display period. On the other hand, in the coordinate detection period, when the DC voltage V _GOFF for turning off the TFT 54 is applied and selected by scanning by the shift register 78, the corresponding input / output terminal G to the gate bus line electrode 56. Take in the induced voltage. The induced voltage thus fetched is sent to the y-coordinate detection circuit 66 via the operational amplifier 65.

Further, the analog switch 79 is connected to the gate bus line electrode 56 from the corresponding input / output terminal G to the TFT 5 when the analog switch 79 is not selected by the scanning by the shift register 78 in any of the display period and the coordinate detection circuit.
4. _Send out voltage V _GOFF to turn "4" off.

A technique for enabling the display-integrated type tablet device in the seventh embodiment of the first and second examples to fully exhibit its function will be described below.

[Eighth Embodiment] A high frequency voltage is applied from a high frequency power source 12 to the tip electrode of the electronic pen 11. Therefore, the tip electrode of the electronic pen 11 is accidentally brought into contact with a metal body having a ground potential placed around the liquid crystal panels 1 and 51 to damage the high frequency power source 12, or the electronic circuit is brought into contact with another electronic circuit. May be damaged.
Further, it is dangerous for the tip electrode of the electronic pen 11 to come into contact with the human body. Therefore, it is desirable to cover the tip of the electronic pen 11 with a dielectric. In each of the above-described embodiments, coordinate detection is performed based on the capacitance of the tip electrode of the electronic pen 11 and the segment electrode X or the common electrode Y, the source bus line electrode 57, or the gate bus line electrode 56. There is no functional problem even if the tip of the pen 11 is covered with a dielectric.

[Ninth Embodiment] FIG. 18 shows the electronic pen 1 described above.
1 is a schematic block diagram of a display-integrated type tablet device that can use 1 in a cordless manner. Incidentally, in FIG. 18, only the elements necessary for making the cordless are described, and the others are omitted. Further, the x-direction driving system and the y-direction driving system are collectively expressed as one system.

The high frequency power source 12 for applying a high frequency voltage to the tip electrode (not shown) of the electronic pen 11 is built in the electronic pen 11 having an active element and a battery. And
The ground of the electronic pen 11 and the human body holding the electronic pen 11 are coupled by electrostatic capacitance. Further, the human body is further coupled to the ground of the display-integrated tablet system by electrostatic capacitance directly or via a power transformer. Therefore, due to the high frequency voltage applied from the high frequency power supply 12 to the tip electrode, the liquid crystal panels 1, 5
An induced voltage is generated in the segment electrode X and the common electrode Y of No. 1, the source bus line electrode 57, and the gate bus line electrode 56, and the tip electrode of the electronic pen 11 can be detected.

When the electronic pen 11 is provided with a code, information from a pen touch switch of the electronic pen 11 (a switch for detecting whether or not the pen is being input: not shown) is supplied via the code. Coordinate detection circuit 8, 9, 66,
69 and the control circuit 10. However, in the case of cordless, the above information cannot be transmitted. Therefore, in the present embodiment, the above-mentioned information is transmitted by modulating the high frequency voltage applied to the tip electrode of the electronic pen 11 with a predetermined frequency or amplitude, and the coordinate detection circuits 8, 9, 6 are transmitted.
The demodulation is performed with 6,69.

In the display-integrated tablet device,
The high frequency voltage is applied to the tip electrode only when the pen touch switch is turned "on", so that the consumption of the battery in the high frequency power supply 12 can be suppressed to the minimum. The battery is not particularly limited and may be a solar battery, a rechargeable battery or the like. At that time, in the case of a rechargeable battery, the electronic pen 11 can be connected to the display-integrated tablet side with a power cord as needed, and when the battery voltage drops due to discharge, the display-integrated tablet side It is possible to apply a high-frequency voltage to the tip electrode and charge the battery by supplying power from the.

[Tenth Embodiment] FIGS. 19 and 20 are views showing a display-integrated type tablet device different from the seventh embodiment. In the display-integrated type tablet device according to the present embodiment, an operational amplifier 81 is connected to the electronic pen 11 instead of a high frequency power source, and an induced voltage input from the tip electrode of the electronic pen 11 via the operational amplifier 81 is applied. Based on the coordinate detection circuit 82, the coordinates of the tip of the electronic pen 11 are calculated, and the x coordinate signal and y
Output the coordinate signal.

As described above, during the coordinate detection period in this embodiment, when the scanning voltage pulse is sequentially applied to the gate bus line electrode 56 and the source bus line electrode 57, it is induced in the tip electrode of the electronic pen 11. Since the tip coordinates of the electronic pen 11 are detected based on the induced voltage, the following problems occur when scanning the gate bus line electrode 56. That is, when a scanning voltage is applied to the gate bus line electrode 56 during the coordinate detection period, the TFT 5
Since a voltage is applied to the gate electrode of No. 4, the TFT 54 is turned "on". Therefore, in the display period, the pixel electrode 55
The display charge accumulated in the display is discharged and the display state changes.

Therefore, in order to solve the above-mentioned problem, the y coordinate detection in this embodiment is carried out during the display period. Then, in this case, in order to improve the detection accuracy of the y-coordinate, a high frequency to be the coordinate detection signal is superimposed on the selection pulse of the gate bus line electrode drive signal as shown in FIG. Thus, the gate bus line electrode 56 is driven by the gate bus line electrode drive signal on which the high frequency is superimposed.
The induced voltage induced in the tip electrode of the electronic pen 11 when the images are displayed on the liquid crystal panel 51 by sequentially driving and is input to the coordinate detection circuit 82. Then, the coordinate detection circuit 8
2 is a built-in filter that allows only the high-frequency component to pass and is rectified, and the electronic pen 11 is based on the obtained voltage signal.
Detect the x coordinate of the tip. The above-described effect can be obtained by superimposing a high frequency pulse on the selection pulse of the gate bus line electrode drive signal as shown in FIG.

The above-described operation can be easily realized by supplying a voltage including a high frequency component as the power supply V _GON input to the gate drive circuit 83.

The x-coordinate detection is carried out as follows during the x-coordinate detection period. That is, first, all the analog switches Sg _{1 to} Sg _n of the gate drive circuit 83 are switched to the terminal b side to turn off all the TFTs 54. Next, the source drive circuit 62 causes the shift register 6
Analog switches Ss ₁ ~ SS _m is switched sequentially to the terminal c side as 7 output, scan pulse voltage V _SON source bus line scan signals to the source bus line electrodes 57 are scanned sequentially applied. In this way, the coordinate detection circuit 82 causes the electronic pen 1 to operate based on the induced voltage induced in the tip electrode of the electronic pen 11 due to the source bus line electrode scanning signal sequentially applied to the source bus line electrode 57.
The x coordinate of one tip is detected.

The gate bus line electrode scanning in this embodiment is performed for each gate bus line electrode 56 because it is performed during the display period, but the driving speed of the gate bus line electrodes during the display period is slow and This is not a problem because the selection pulse voltage of the gate bus line electrode drive signal is high. In addition, since the source bus line electrode scanning is performed during the x coordinate detection period, the plurality of source bus line electrodes 5 are
7 are scanned simultaneously.

The above is a description of the display-integrated type tablet device using the active matrix type liquid crystal panel 51.

A technique for enabling the display-integrated type tablet device in the first and second examples to fully exhibit its functions will be described below.

[Eleventh Embodiment] In general, the liquid crystal panel 1,
51 is illuminated from the back by a fluorescent lamp or a backlight composed of an EL panel (electroluminescence panel). Since this backlight is turned on by a high frequency voltage, an induced voltage is generated in the segment electrode X and the common electrode Y during the coordinate detection period, which deteriorates the coordinate detection accuracy. In particular, when inducing an induced voltage in the lower electrode due to the high-frequency voltage applied to the tip electrode of the electronic pen 11, the induced voltage is low, so that the backlight lighting voltage has a large effect. . For example, when a fluorescent lamp is used as the backlight, the lighting frequency when the lighting voltage is several tens of volts is 20 kHz to 40 kHz.

In order to avoid this, the following measures should be taken. First measure: The light source of the above backlight and its power source are electrostatically shielded. However, the optical path from the backlight may be blocked, and there is a limit to this measure.

Second Countermeasure The power source frequency of the backlight and the frequency of the high frequency voltage from the high frequency power source 12 applied to the tip voltage of the electronic pen 11 are set to different frequencies. Then, the x-coordinate detection circuit 8
Further, the y-coordinate detection circuit 9 is provided with a filter that allows only the frequency of the high frequency power source 12 to pass. At that time, since the power supply frequency of the backlight includes harmonics, it is necessary to prevent the voltage frequency to the electronic pen 11 from being an odd multiple of the power supply frequency of the backlight.

Third Countermeasure In the display-integrated type tablet device in each of the above embodiments,
The display period and the coordinate detection period are time-divisionally operated. Then, it is only the display period that the backlight needs to illuminate. Therefore, the backlight is driven only during the display period, and the application of the power supply voltage to the light source of the backlight is stopped during the coordinate detection period. Coordinate detection period is 1ms
Since it is less than or equal to ec, even if the backlight is turned off during the coordinate detection period, light is immediately emitted if a power supply voltage is applied to the light source of the backlight at the start of the display period.

More specifically, as shown in FIG. 4, the coordinate detection preparation period is provided before the display period ends and the x coordinate detection period starts. Similarly, y
A display preparation period (not shown) is provided before the display period starts after the coordinate detection period ends. Therefore, the power supply of the backlight is "turned on / off" using the coordinate detection preparation period and the display preparation period. By doing this, the backlight power is not turned “on / off” during the display period and coordinate detection period described above, and therefore coordinate misdetection due to illumination spots during the display period and transient noise that occurs during turning on / off can be prevented. Does not happen.

[Twelfth Embodiment] In the coordinate detecting circuit in each of the above embodiments, the time Ts, T as shown in FIG.
The x coordinate or the y coordinate of the tip of the electronic pen is detected based on r and Tg. Here, the time Ts, Tr, T
g is designed to count the time by counting the number of timekeeping pulses. Therefore, by setting the frequency of the clock pulse to be higher than the frequency of the clock signal cp1o which is the scanning signal of the segment electrode X and the common electrode Y, the time Ts, Tr, Tg is clocked more accurately, and the time of the electronic pen is measured. The tip coordinates can be detected more accurately.

In each of the above embodiments, the image display on the liquid crystal panels 1 and 51 is performed based on the 4-bit display data Do _{0 to} Do ₃ input to the segment drive circuit 3 or the source drive circuit 62. I have to. However, the present invention is not limited to this, and display data of 8 bits or 16 bits may be used.

[0213]

As is apparent from the above, in the display-integrated type tablet device according to the first invention, the display control circuit is operated in the display period in which the display control circuit side is selected by the switching circuit according to the control of the control circuit. The common drive circuit generates a common electrode drive signal based on the display control signal and the display data, while the segment drive circuit generates a segment electrode drive signal. Then, the pixel associated with the common electrode selected by the generated common electrode drive signal is displayed according to the display data by the segment electrode drive signal. Further, in the coordinate detection period in which the detection control circuit side is selected by the switching circuit, the segment drive circuit scans the segment electrodes by the voltage detection circuit based on the detection control signal output from the detection control circuit. The voltage of the scan segment electrode is detected. Then, the x-coordinate of the tip of the electronic pen is detected by the coordinate detection circuit based on the induced voltage induced in each segment electrode due to the high frequency voltage applied to the electrode of the electronic pen. On the other hand, the common drive circuit scans the common electrode and the voltage detection circuit detects the voltage of the scan common electrode. Then, the y coordinate of the tip of the electronic pen is detected by the coordinate detection circuit based on the induced voltage induced in each common electrode due to the high frequency voltage applied to the electrode of the electronic pen.

That is, the liquid crystal panel functions as a display unit during the display period, and functions as a tablet during the coordinate detection period. In other words,
The display function is integrated into the tablet. Therefore, according to the present invention, it is not necessary to stack the tablet on the display unit, the display screen can be easily seen when the position on the display screen is input by a pen, and the size and cost can be easily reduced. . Further, by adopting the polymer dispersion type liquid crystal as the liquid crystal of the liquid crystal panel, it becomes possible to realize a notebook computer having a flexible sheet tablet.

In the display-integrated type tablet device according to the second aspect of the invention, the common drive circuit and the segment drive circuit each have a voltage transmitting / receiving means, and during the display period, the common electrode via the voltage transmitting / receiving means. While the voltage based on the drive signal or the segment electrode drive signal is sent to each of the common electrodes or each of the segment electrodes, in the coordinate detection period, the induced voltage from the scan common electrode or the scan segment electrode is transmitted through the voltage transmission / reception means. Since the voltage is sent to the voltage detection circuit, it is possible to apply the voltage to the common electrode or the segment electrode during the display period and read the induced voltage of the common electrode or the segment electrode during the coordinate detection period.

In the display-integrated type tablet device of the third invention, one end of the voltage transmission / reception means of the second invention is commonly connected to the power supply section and the voltage detection circuit, while the other end thereof is connected. Since it is composed of multiple bidirectional analog switch circuits connected to each common electrode or each segment electrode, application of voltage to the common electrode or segment electrode during the above display period and common electrode or segment electrode during the above coordinate detection period It is possible to easily realize the reading of the induced voltage of.

Further, in the display-integrated type tablet device of the fourth invention, one of the common drive circuit and the segment drive circuit which scans at least one of the electrodes farther from the electronic pen in the coordinate detection period is scanned. Since the drive circuit simultaneously scans a predetermined number of electrodes, which is larger than the number of electrodes simultaneously scanned by the other drive circuit, the induced voltage value obtained by scanning the electrode farther from the electronic pen is To be enhanced. Therefore, in the coordinate detection period, it is possible to prevent the induced voltage from decreasing when scanning the electrode farther from the electronic pen, and to stably detect the x coordinate and the y coordinate of the tip of the electronic pen. it can.

In the display-integrated tablet device according to the fifth aspect of the present invention, the electrode of the common electrode or the segment electrode, which is farther from the electronic pen, is scanned with the electrode of the electronic pen. The electronic pen is provided with a high frequency power source for applying a high frequency voltage of a first voltage and a second frequency voltage lower than the first voltage when the other electrode is scanned. The value of the induced voltage induced in the electrode at the longer distance is increased. Therefore,
During the coordinate detection period, it is possible to prevent the induced voltage from decreasing when scanning the electrode farther from the electronic pen, and it is possible to stably detect the x coordinate and the y coordinate of the tip of the electronic pen.

Further, in the display-integrated type tablet device of the sixth invention, the coordinate detection circuit has an amplifier and scans one of the common electrode or the segment electrode which is farther from the electronic pen. In this case, the coordinate detection circuit detects the coordinates of the tip of the electronic pen based on the induced voltage amplified by the first amplification factor, while the other electrode is scanned by the coordinate detection circuit. Since the coordinates of the tip of the electronic pen are detected based on the induced voltage after being amplified by the second amplification rate that is smaller than the amplification rate of, the induction voltage induced in the electrode farther from the electronic pen is larger. Is amplified. Therefore, during the coordinate detection period, the coordinate detection accuracy is prevented from being lowered when scanning the electrode farther from the electronic pen, and the x-coordinate and the y-coordinate of the tip of the electronic pen are stabilized with the same accuracy. Can be detected.

Further, in the display-integrated type tablet device according to the seventh invention, the voltage detection circuit has voltage application means, and the voltage application means does not apply to the scanning common electrode or the scanning segment electrode during the coordinate detection period. Since the same voltage as that of the scanning common electrode or the non-scanning segment electrode is applied, the DC voltage of the scanning electrode is stably maintained when the common electrode or the segment electrode is scanned.

In the display-integrated type tablet device of the eighth invention, the display alternating signal is generated by the display alternating signal generator in the display period, while the detected alternating signal generator is generated in the coordinate detecting period. Generates a detection alternating current signal for inverting the voltage applied to the liquid crystal at a time other than the common electrode scanning period and the segment electrode scanning period, and based on the generated display alternating current signal and detection alternating current signal, the common signal The drive circuit generates a common electrode drive signal and scans the common electrode so that the application direction of the voltage applied to the liquid crystal of each pixel is reversed. Also,
The segment drive circuit generates a segment electrode drive signal and scans the segment electrode so that the application direction of the voltage applied to the liquid crystal of each pixel is inverted. Therefore, according to the present invention, the application direction of the voltage applied to the liquid crystal can be reversed independently of the display period even during the coordinate detection period, and it is possible to prevent a decrease in life due to electrolysis of the liquid crystal.

Further, in the display-integrated type tablet device of the ninth invention, the switching circuit is switched under the control of the control circuit, and in the display period, it is generated by the gate drive circuit in accordance with the signal from the display control circuit. The gate bus line electrodes of the active matrix type liquid crystal panel are sequentially selected based on the gate bus line electrode drive signals, and the selected gate bus line electrodes are selected based on the source bus line electrode drive signals generated by the source drive circuit. The pixels related to are displayed according to the display data. On the other hand, in the coordinate detection period, the gate bus line electrode or the source bus line electrode is sequentially scanned according to the signal from the detection control circuit without operating the active element by the gate drive circuit and the source drive circuit, and the electrode of the electronic pen is scanned. The voltage detection circuit detects the induced voltage induced in the gate bus line electrode or the source bus line electrode due to the high frequency voltage applied to the electronic pen by the coordinate detection circuit based on the detected induced voltage. Detect the tip coordinates. Therefore, according to the present invention, a display-integrated type tablet device using an active matrix type liquid crystal panel can be realized.

In the display-integrated type tablet device of the tenth invention, at least one of the gate drive circuit and the source drive circuit has a predetermined number of bus line electrodes in the liquid crystal panel during the coordinate detection period. Since scanning is performed at the same time, even in an active matrix type liquid crystal panel having thin electrodes and a high density, the tip coordinates of the electronic pen can be accurately detected based on the high induction voltage induced in the predetermined number of electrodes.

Also, in the display-integrated type tablet device of the eleventh invention, the cycle of the high frequency voltage applied to the electrode of the electronic pen is such that the common drive circuit, the segment drive circuit and the gate drive circuit in the coordinate detection period are Since it is shorter than the electrode scanning cycle of the source drive circuit, it is possible to reliably detect the induced voltage induced in each of the electrodes due to the high frequency voltage applied to the electrode of the electronic pen. In this way, the tip coordinates of the electronic pen and the high-speed coordinates are accurately detected in the liquid crystal panel of the high-density pixel matrix.

Further, in the display-integrated type tablet device according to the twelfth aspect of the invention, the coordinate detecting circuit is provided with a filter for separating the same high frequency component as the frequency of the high frequency voltage applied to the electronic pen, and during the coordinate detecting period. , The high-frequency component in the induced voltage induced in the common electrode and the segment electrode, the gate bus line electrode, and the source bus line electrode detected by the voltage detection circuit is separated by the filter, and the separated high-frequency component is obtained. Since the tip coordinates of the detection pen are detected based on the above, it is possible to accurately detect the tip coordinates of the electronic pen by separating the noise induced in each electrode. Further, according to the present invention, by frequency-modulating the high frequency voltage applied to the electronic pen, information such as the start of pen input can be superimposed on the high frequency voltage.

In the display-integrated type tablet device of the thirteenth invention, a high-frequency power source for supplying a high-frequency voltage to the electrodes of the electronic pen is constructed in the electronic pen to have a high-frequency generating power source and an active element. Therefore, the high frequency voltage can be applied to the electrodes of the electronic pen without a cord.

In the display-integrated type tablet device of the fourteenth invention, the electronic pen is provided with input detection means for detecting the start of pen input and outputting a detection signal. Since the high frequency voltage is generated based on the detection signal from the input detection means, the high frequency voltage can be applied to the electrode of the electronic pen only when necessary. Therefore, when the high frequency power source is composed of a battery, it is possible to prevent unnecessary consumption of the battery.

Further, in the display-integrated type tablet device of the fifteenth invention, since the electrodes of the electronic pen are covered with the dielectric,
It is possible to provide a display-integrated tablet device that allows safe pen input to an external electronic circuit or a human body.

In the display-integrated type tablet device of the sixteenth invention, the switching circuit is switched under the control of the control circuit, and in the display period, it is generated by the gate drive circuit in accordance with the signal from the display control circuit. Source bus line electrode drive signals generated by a source drive circuit for sequentially selecting gate bus line electrodes of an active matrix type liquid crystal panel based on the gate bus line electrode drive signals, and for pixels associated with the selected gate bus line electrode It is displayed according to the display data based on. On the other hand, in the coordinate detection period, a gate bus line for sequentially scanning the gate bus line electrode and the source bus line electrode according to a signal from the detection control circuit without operating the active element by the gate drive circuit and the source drive circuit. An electrode scanning signal and a source bus line electrode scanning signal are generated, and the electronic bus of the electronic pen is caused by the gate bus line electrode scanning signal and the source bus line electrode scanning signal applied to the gate bus line electrode and the source bus line electrode. The induced voltage induced in the electrodes is detected, and the coordinate detection circuit detects the tip coordinates of the electronic pen based on the detected induced voltage. Therefore, according to the present invention, a display-integrated type tablet device using an active matrix type liquid crystal panel can be realized.

Further, a display-integrated type tablet device according to a seventeenth invention is characterized in that the gate drive circuit in the display-integrated type tablet device according to the sixteenth invention is provided in the display period.
The gate bus line electrode drive signal is generated by superimposing the coordinate detection signal on the selection pulse of the gate bus line electrode drive signal, and the coordinate detection circuit separates the coordinate detection signal component of the induced voltage input from the electronic pen. Is provided, and the coordinate detection signal component of the induced voltage induced in the electrode of the electronic pen due to the gate bus line electrode drive signal in which the high frequency is superimposed on the selection pulse is separated by the filter. Since the y coordinate of the tip of the electronic pen is detected based on the coordinate detection signal component, the gate bus line electrode scanning signal is applied to the gate bus line electrode during the y coordinate detection period to drive the active element. Can be prevented.

Further, in the display-integrated type tablet device of the eighteenth invention, the illumination means for illuminating the liquid crystal panel from the back is driven under the control of the control circuit, and the control circuit controls the switching circuit. Since the liquid crystal panel is irradiated only during the period in which the display period is set, noise induced in the common electrode and the segment electrode, the gate bus line electrode, the source bus line electrode, etc. of the liquid crystal panel in the coordinate detection period is To be prevented. Therefore, according to the present invention, the tip coordinates of the electronic pen can be accurately detected.

[Brief description of drawings]

FIG. 1 is a block diagram of one embodiment of a display-integrated tablet device according to a first example of the present invention.

2 is a block diagram of a segment drive circuit in FIG. 1. FIG.

FIG. 3 is a timing chart of a display period and a coordinate detection period.

4 is a diagram showing an example of a scanning timing of each segment electrode performed in an x coordinate detection period and a scanning timing of each common electrode performed in ay coordinate detection period in FIG.

5 is a block diagram of a display-integrated type tablet device different from FIG.

6 is a block diagram of a segment drive circuit in FIG.

FIG. 7 is a block diagram of a segment drive circuit different from that of FIG.

FIG. 8 is an explanatory diagram of a scanning timing of each segment electrode and a scanning timing of each common electrode when scanning a plurality of electrodes at once.

FIG. 9 is an explanatory diagram of distributed resistance and distributed capacitance between a segment electrode and a common electrode.

FIG. 10 is a block diagram of a duty type liquid crystal display device.

11 is a block diagram of the common drive circuit in FIG.

12 is a timing chart of a common electrode drive signal and a segment electrode drive signal in the duty type liquid crystal display device shown in FIG.

13 is an explanatory diagram of a display image based on the common electrode drive signal and the segment electrode drive signal shown in FIG.

14 is an explanatory diagram of a level inversion cycle of an alternating signal in the duty type liquid crystal display device shown in FIG.

FIG. 15 is a diagram showing a relationship between a liquid crystal panel by a TFT method and an electronic pen in a display-integrated type tablet device according to a second example of the present invention.

16 is a block diagram of a main part of the display-integrated type tablet device shown in FIG.

17 is a block diagram showing another example of the gate drive circuit in FIG.

FIG. 18 is a schematic block diagram of a display-integrated tablet device in which an electronic pen can be used without a cord.

19 is a diagram showing a relationship between a liquid crystal panel and an electronic pen in a TFT system in a display-integrated tablet device according to a second example different from FIG.

20 is a block diagram of essential parts of the display-integrated tablet device shown in FIG. 19. FIG.

21 is a diagram showing an example of a gate bus line electrode drive signal in the display-integrated type tablet device shown in FIG. 20.

22 is a diagram showing a gate bus line electrode drive signal different from that in FIG. 21. FIG.

FIG. 23 is a block diagram of an electrostatic induction tablet and its drive unit.

FIG. 24 is a diagram showing an example of column electrode scanning signals and row electrode scanning signals.

FIG. 25 is an explanatory diagram of signal waveforms output from the electronic pen in FIG. 23.

[Explanation of symbols]

1, 51 ... Liquid crystal panel, 2 ... Common drive circuit, 3 ... Segment drive circuit, 4 ... Display control circuit, 5 ... Power supply circuit, 6 ...
Detection control circuit, 7 ... switching circuit,
8,69 ... x coordinate detection circuit, 9,66 ... y coordinate detection circuit,
10 ... Control circuit, 11 ... Electronic pen,
12 ... High frequency power supply, 13, 14, 65, 6
8,81 ... Operational amplifier, 15,25 ... Data latch circuit, 16,26 ... Line latch circuit,
17, 27 ... Shift register, 18, 28 ... Level shifter, 19, 29 ... Control circuit, 5
4 ... TFT, 56 ... Gate bus line electrode, 5
7 ... Source bus line electrodes, 61, 75, 83 ... Gate drive circuit, 62 Source drive circuit, 82 ... Coordinate detection circuit.

Claims (18)

[Claims] 1. A liquid crystal panel having a plurality of segment electrodes arranged in parallel and a plurality of common electrodes arranged in parallel orthogonal to the segment electrodes and driven by a duty type driving method, and the liquid crystal. An electronic pen having an electrode to which a high-frequency voltage is applied by being coupled to the segment electrode and the common electrode of the panel by stray capacitance, and an intersection region of the plurality of segment electrodes and the plurality of common electrodes of the liquid crystal panel. A display control circuit for outputting a display control signal and display data for displaying an image on a pixel matrix; a detection control circuit for outputting a scan control signal for scanning the segment electrodes and common electrodes of the liquid crystal panel; and a control circuit Is controlled by the display control circuit side during the display period. A display control signal and display data are output from the display control circuit, and a switching circuit that switches and selects the detection control circuit side and outputs a scan control signal from the detection control circuit during the coordinate detection period; During the period, a common electrode drive signal for sequentially selecting the common electrodes is generated based on the display control signal from the switching circuit, while during the coordinate detection period, the common electrode drive signal is generated based on the scanning control signal from the switching circuit. A common drive circuit that sequentially scans the common electrodes without displaying an image on the pixel matrix, and a common selected by the common electrode drive signal based on the display control signal and display data from the switching circuit during the display period. While the segment electrode drive signal for displaying the pixel related to the electrode is generated, the coordinate detection period Is a segment drive circuit that sequentially scans the segment electrodes without displaying an image in the pixel matrix based on a scan control signal from the switching circuit; and a high frequency applied to the electrodes of the electronic pen during the coordinate detection period. A voltage detection circuit for detecting an induced voltage induced in the scan common electrode by the common drive circuit or the scan segment electrode by the segment drive circuit due to the voltage, and the induction voltage of each common electrode detected by the voltage detection circuit. And the induced voltage of each segment electrode is input, and during the coordinate detection period, the coordinate of the tip of the electronic pen is detected by a predetermined procedure based on the input induced voltage, and the x coordinate signal or the y coordinate signal is obtained. A coordinate detection circuit for outputting is provided, and the display period and The target detection period is appropriately set, and an image is displayed on the pixel matrix of the liquid crystal panel during the set display period, while the liquid crystal panel is displayed without displaying an image on the pixel matrix during the coordinate detection period. A display-integrated type tablet device characterized by detecting the tip position of the electronic pen above. 2. The display-integrated tablet device according to claim 1, wherein the common drive circuit and the segment drive circuit each have a voltage transmission / reception means, and during the display period, the generated common electrode drive signal or segment. While the voltage based on the voltage drive signal is sent to the common electrodes or the segment electrodes via the voltage sending / receiving means, the induced voltage from the scanning common electrode or the scanning segment electrode is sent to the voltage sending / receiving means in the coordinate detection period. A display-integrated type tablet device, characterized in that it is sent to the voltage detection circuit via the. 3. The display-integrated tablet device according to claim 2, wherein the voltage transmission / reception means has one end commonly connected to the power supply and the voltage detection circuit, and the other end having an individual common electrode or an individual electrode. It is composed of a plurality of bidirectional analog switch circuits connected to the segment electrodes of the above, and during the display period, it takes in a predetermined voltage from the power supply unit on the one end side and sends it to the common electrode or the segment electrode on the other end side. On the other hand, the display-integrated tablet device, characterized in that, during the coordinate detection period, the induced voltage of the common electrode or the segment electrode on the other end side is captured and sent to the voltage detection circuit on the one end side. 4. The display-integrated tablet device according to any one of claims 1 to 3, wherein at least one of the common drive circuit and the segment drive circuit, which is farther from the electronic pen, is an electrode. The display-integrated type tablet device, wherein one of the driving circuits for scanning simultaneously scans a predetermined number of electrodes, which is larger than the number of electrodes simultaneously scanned by the other driving circuit, during the coordinate detection period. 5. The display-integrated tablet device according to claim 1, wherein an electrode of the common electrode or the segment electrode that is farther from the electronic pen is scanned. In this case, a high frequency voltage of a first voltage is applied to the electrode of the electronic pen, while a high frequency voltage of a second voltage lower than the first voltage is applied when the other electrode is scanned. A display-integrated tablet device characterized by having a power supply. 6. The display-integrated tablet device according to any one of claims 1 to 5, wherein the coordinate detection circuit has an amplifier and is provided with the electronic pen among the common electrodes or the segment electrodes. When determining the electronic pen tip coordinate based on the induced voltage induced in the electrode with the longer distance, the electronic pen tip coordinate is obtained after amplifying the induced voltage by the first amplification factor. When obtaining the electronic pen tip coordinate based on the induced voltage induced in the electrode, it is necessary to obtain the electronic pen tip coordinate after amplifying the induced voltage by a second amplification rate smaller than the first amplification rate. Characteristic integrated tablet device. 7. The display-integrated type tablet device according to claim 1, wherein the voltage detection circuit has a voltage application unit, and the voltage application unit has the voltage application unit during the coordinate detection period. The display-integrated type tablet device, wherein the same voltage as that of the non-scanning common electrode or the non-scanning segment electrode is applied to the scanning common electrode or the scanning segment electrode. 8. The display-integrated tablet device according to claim 1, wherein a point at which a voltage applied to the liquid crystal of each pixel in the pixel matrix is reversed during the display period. A display alternating current signal generation unit for generating a display alternating current signal for setting, and a point at which the application direction of the voltage applied to the liquid crystal of each pixel is reversed during the coordinate detection period to set the common electrode scanning period and the segment. The common drive circuit and the segment drive circuit are provided with a detection AC signal generation unit that generates a detection AC signal for inverting the application direction of the voltage at a time other than the electrode scanning period. A common electrode drive signal or a segment electrode drive signal that reverses the application direction of the voltage applied to the liquid crystal of each pixel based on the display alternating signal On the other hand, in the coordinate detection period, the common electrode is configured such that the application direction of the voltage applied to the liquid crystal is inverted based on the detected alternating current signal at times other than the common electrode scanning period and the segment electrode scanning period. A display-integrated type tablet device characterized by generating a scanning signal or a segment electrode scanning signal. 9. A gate bus line electrode having a plurality of gate bus line electrodes arranged in parallel on a transparent substrate and a plurality of source bus line electrodes arranged in parallel to and orthogonal to the gate bus line electrodes. An active matrix type liquid crystal panel driven by a plurality of active elements arranged at intersections of the bus line electrodes and an input terminal connected to the source bus line electrodes while a control terminal is connected to the liquid crystal panel. An electronic pen which is located on the side of the transparent substrate having the active element in the panel and has at its tip an electrode to which a high frequency voltage is applied by being coupled to the gate bus line electrode and the source bus line electrode by stray capacitance, and the liquid crystal panel. In a plurality of regions surrounded by a plurality of gate bus line electrodes and a plurality of source bus line electrodes in A display control circuit for outputting a display control signal and display data for displaying an image on the pixel matrix configured as described above; and a scan control signal for scanning the gate bus line electrode and the source bus line electrode of the liquid crystal panel. Controlled by the detection control circuit that outputs and the control circuit, the display control circuit side is switched and selected during the display period to output the display control signal and the display data from the display control circuit, while the coordinate detection period is performed. A switching circuit that switches and selects the detection control circuit side to output a scanning control signal from the detection control circuit, and sequentially selects the gate bus line electrodes based on the display control signal from the switching circuit during the display period. A gate bus line electrode drive signal for generating the A gate drive circuit that sequentially scans the gate bus line electrodes without operating the active elements based on the scanning control signal, and the gate based on a display control signal and display data from the switching circuit during the display period. A source bus line electrode drive signal for displaying a pixel associated with the gate bus line electrode selected by the bus line electrode drive signal is generated, while the source bus line electrode drive signal is generated based on a scanning control signal from the switching circuit during the coordinate detection period. A source driving circuit for sequentially scanning the source bus line electrodes, and a scanning gate bus line electrode by the gate driving circuit or the source driving circuit by the high frequency voltage applied to the electrode of the electronic pen during the coordinate detection period. A voltage detection circuit for detecting the induced voltage induced in the scanning source bus line electrode and The induced voltage of each gate bus line electrode and the induced voltage of each source bus line electrode detected by the voltage detection circuit are input, and in the coordinate detection period, a predetermined procedure is performed based on the input induced voltage. A coordinate detection circuit for detecting the coordinates of the tip of the electronic pen and outputting an x-coordinate signal or a y-coordinate signal is provided, and the display period and the coordinate detection period are appropriately set by the control circuit. In the above, the display-integrated tablet device is characterized in that while displaying an image on the pixel matrix of the liquid crystal panel, the tip position of the electronic pen on the liquid crystal panel is detected during the coordinate detection period. 10. The display-integrated tablet device according to claim 9, wherein at least one of the gate drive circuit and the source drive circuit has a predetermined number of bus lines in the liquid crystal panel during the coordinate detection period. A display-integrated tablet device characterized by scanning electrodes simultaneously. 11. The display-integrated tablet device according to claim 1, wherein the cycle of the high-frequency voltage applied to the electrodes of the electronic pen is:
A display-integrated tablet device, characterized in that it is shorter than an electrode scanning period of a common drive circuit, a segment drive circuit, a gate drive circuit, and a source drive circuit in the coordinate detection period. 12. The display-integrated tablet device according to claim 1, wherein the coordinate detection circuit generates the same frequency component as the frequency of the high frequency voltage applied to the electrode of the electronic pen. In the coordinate detection period, the high frequency component of the induced voltage induced in the common electrode and the segment electrode, the gate bus line electrode, and the source bus line electrode detected by the voltage detection circuit is included in the coordinate detection period. A display-integrated tablet device, characterized in that it is separated by a filter, and the coordinates of the tip of the electronic pen are detected by a predetermined procedure based on the separated high-frequency component. 13. The display-integrated tablet device according to claim 1, wherein the high-frequency power source for supplying a high-frequency voltage to the electrodes of the electronic pen is a high-frequency voltage generating power source and an active element. A display-integrated type tablet device having the above-mentioned structure and being configured in the electronic pen. 14. The display-integrated tablet device according to claim 13, wherein the electronic pen has input detection means for detecting the start of pen input and outputting a detection signal, and the high-frequency voltage generator is provided. A display-integrated type tablet device, wherein the power source for generating a high frequency voltage based on a detection signal from the input detection means. 15. The display-integrated tablet device according to claim 1, wherein the electrode of the electronic pen is covered with a dielectric. 16. A gate bus line electrode having a plurality of gate bus line electrodes arranged in parallel on a transparent substrate and a plurality of source bus line electrodes arranged in parallel to and orthogonal to the gate bus line electrodes. An active matrix type liquid crystal panel driven by a plurality of active elements arranged at intersections of the bus line electrodes and an input terminal connected to the source bus line electrodes while a control terminal is connected to the liquid crystal panel. An electronic pen having a high input impedance electrode, which is located on the transparent substrate side having the active element in the panel and is coupled to the gate bus line electrode and the source bus line electrode by a stray capacitance, and a plurality of the liquid crystal panels. Of the gate bus line electrode and the plurality of source bus line electrodes And a display control circuit for outputting a display control signal and display data for displaying an image on the pixel matrix formed by the above, and a scanning control signal for scanning the gate bus line electrode and the source bus line electrode of the liquid crystal panel. The display control circuit is controlled by the detection control circuit, and the display control circuit is switched and selected in the display period to output the display control signal and the display data from the display control circuit. A switching circuit that switches and selects the detection control circuit side to output a scanning control signal from the detection control circuit, and sequentially selects the gate bus line electrodes based on the display control signal from the switching circuit during the display period. The gate bus line electrode drive signal for generating the A gate drive circuit for generating a gate bus line electrode scan signal for sequentially scanning the gate bus line electrodes without operating the active element based on a scan control signal from the switching circuit during the display period. The source bus line electrode drive signal for displaying the pixel related to the gate bus line electrode selected by the gate bus line electrode drive signal is generated based on the display control signal and the display data of A source driving circuit for generating a source bus line electrode scanning signal for sequentially scanning the source bus line electrodes based on a scanning control signal from the switching circuit; and a gate driving circuit and the source driving circuit to the gate bus line electrodes. Or due to each scanning signal input to the source bus line electrode Serial and induced induced voltage in the electronic pen electrode is entered, in the coordinate detection period,
The coordinates of the tip of the electronic pen are detected by a predetermined procedure based on the input induced voltage from the electronic pen, and x
A coordinate detection circuit that outputs a coordinate signal or a y-coordinate signal is provided, and the display period and the coordinate detection period are appropriately set by the control circuit, and an image is displayed on the pixel matrix of the liquid crystal panel during the set display period. Is displayed, while the tip position of the electronic pen on the liquid crystal panel is detected during the coordinate detection period. 17. The display-integrated tablet device according to claim 16, wherein the gate drive circuit drives a gate bus line electrode by superimposing a coordinate detection signal on a selection pulse in the gate bus line electrode drive signal during the display period. Generate a signal,
The coordinate detection circuit has a filter for separating the coordinate detection signal component of the induced voltage input from the electronic pen, and the coordinate detection signal is superimposed on the selection pulse output from the gate drive circuit during the display period. The coordinate detection signal component of the induced voltage induced in the electrode of the electronic pen by the generated gate bus line electrode drive signal is separated by the filter, and the electronic pen is subjected to a predetermined procedure based on the separated coordinate detection signal component. A display-integrated tablet device characterized by detecting the y-coordinate of the tip. 18. The display-integrated tablet device according to claim 1, wherein the illuminating means for illuminating the liquid crystal panel from the back surface is driven under the control of the control circuit. The display-integrated type tablet device, wherein the control circuit controls the switching circuit to irradiate only the display period set.