JP2747429B2 - Display integrated tablet device - Google Patents

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 having an integrated display function for use in personal computers, word processors, and the like.

[0002]

2. Description of the Related Art Conventionally, there is a display unit-integrated tablet device in which a display unit and a tablet are laminated and integrally formed. FIG. 35 shows a schematic structure of an electrostatic induction tablet used in this display unit integrated type tablet device and its driving unit.

The electrostatic induction tablet 101 has column electrodes 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 ) Are fixed with a glass substrate arranged in parallel with both electrodes orthogonal and opposed to each other via a spacer (a transparent adhesive or the like). Each row electrode Y is connected to a row electrode shift register 102.
, While each column electrode X is connected to a column electrode shift register 103.

At this time, the column electrodes X and the row electrodes Y are formed substantially transparent with indium oxide (ITO) or the like.

The row electrode shift register 102 and the column electrode shift register 103 include a timing generation circuit 104.
It is connected to the. Also, the timing generation circuit 10
4 includes an x-coordinate detection circuit 107 and a y-coordinate detection circuit 10
8 are connected. The x-coordinate detection circuit 107 detects the x-coordinate of the tip of the electronic pen 105 based on a signal from the timing generation circuit 104 and a signal input from the electronic pen 105 via the operational amplifier 106, and 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 configured has a light transmittance of approximately 85%. Therefore, even if the electrostatic induction tablet 101 is stacked on the liquid crystal display, the display screen of the liquid crystal display can be viewed through the electrostatic induction tablet 101. Thus, as described above, the electrostatic induction tablet 101 is stacked on the liquid crystal display to constitute a display unit-integrated tablet device, and the coordinates on the liquid crystal display are input by the pen 101 using the electrostatic induction tablet 101 and the electronic pen 105. You can.

[0007] The electrostatic induction tablet 101 having the above-described structure and its driving section operate as follows.

That is, first, the timing generation circuit 1
From 04, shift data and a clock signal are sent to the column electrode shift register 103. Then, a scanning pulse of the column electrode scanning signal as shown in FIG. 36 is sequentially applied from the column electrode shift register 103 to each column electrode X. Next, similarly, a scanning pulse of a row electrode scanning signal as shown in FIG. 36 is sequentially applied from the row electrode shift register 102 to each row electrode Y. At that time, the electronic pen 105 is made to approach the surface of the electrostatic induction tablet 101.

Then, the tip electrode of the electronic pen 105
(Not shown), and the column electrode X and the row electrode Y are each coupled by a stray capacitance, so that an induced voltage as shown in FIG. here,
An operational amplifier 106 is connected to the tip electrode, and the input impedance of the tip electrode of the electronic pen 105 is set higher than the impedance of the lead wire.

Based on the induced voltage induced at the tip electrode, the electronic pen 105 will be described below.
Is detected.

That is, the induced voltage signal having the waveform shown in FIG. 37A output from the electronic pen 105 is converted into a signal having the waveform shown in FIG. 37B via a low-pass filter and an amplifier. The signal is input to the x-coordinate detection circuit 107 or the y-coordinate detection circuit 108.

The x-coordinate detection circuit 107 supplies a scanning signal as shown in FIG. 36 to the column electrode X ₁ from the column electrode shift register 103 based on the clock signal from the timing generation circuit 104 and the signal from the electronic pen 105. Is applied and the scanning of the column electrode X is started, and then the electronic pen 1
The time (Ts in FIG. 37 (b)) until the peak of the waveform in the signal from 05 is input is measured. Then, an x coordinate signal representing the x coordinate of the tip of the electronic pen 105 is output based on the measured value.

Similarly, the y coordinate detecting circuit 108
Measures the time from the start of scanning of the row electrode Y to the input of the waveform peak of the signal from the electronic pen 105. Then, based on the measured value, the electronic pen 1
The y-coordinate signal representing the y-coordinate of the tip of the block 05 is output.

At this time, the time Ts is measured by the row electrode shift register 102 or the column electrode shift register 10.
3 is measured by counting the number of pulses of the clock signal applied to the signal No. 3.

An electronic pen 1 is provided by the following method.
It is also possible to more accurately calculate the tip coordinates of 05. That is, the x coordinate detection circuit 107 normalizes the peak value of each step in the step-like waveform of the signal from the electronic pen 105 as shown in FIG. Thereafter, the x-coordinate of the column electrode X _m1 to which the scanning signal is applied when exhibiting the maximum peak value (that is, the x-coordinate of the column electrode X _m1 closest to the tip of the electronic pen 105: the time Ts associated with the maximum peak value) ) And the x coordinate of the column electrode X _m2 to which the scanning signal is applied when exhibiting the second highest peak value (that is, the x coordinate of the column electrode X _m2 closest to the tip of the electronic pen 105). : Calculated from the time Ts associated with the second highest peak value) according to the ratio between the maximum peak value and the second highest peak value. Thus, the x coordinate of the tip of the electronic pen 105 located between the column electrode X _m1 and the column electrode X _m2 is obtained.

Similarly, the y-coordinate detection circuit 108 detects the row electrode Y _n1 closest to the tip of the electronic pen 105 based on the ratio between the maximum peak value of the signal from the electronic pen 105 and the second highest peak value. The y coordinate of the tip of the electronic pen 105 located between the second row electrode Y _n2 and the second closest row electrode Y _n2 is determined.

By doing so, even if the pitch of each column electrode X or the pitch of each row electrode Y is coarse,
The coordinates of the tip of the electronic pen 105 can be accurately calculated. Note that normalizing the peak value of each step of the step-like waveform in the signal from the electronic pen 105 with the maximum peak value is as follows.
This is to prevent an error from occurring even when the tip of the electronic pen 105 is separated from the surface of the electrostatic induction tablet 101.

As described above, the electrostatic induction tablet 101
Although it has a relatively simple structure, it can obtain the coordinates of the tip of the electronic pen 105 with high accuracy, and is widely used in small computers and the like.

[0019]

The above-described electrostatic induction tablet 101 and a liquid crystal display are stacked to display pixels on the liquid crystal display corresponding to the coordinates of the tip of the electronic pen 105 on the electrostatic induction tablet 101. The display unit integrated type tablet device as described above is configured. This tablet device with an integrated display unit traces the surface of the electrostatic induction tablet 101 with the tip of the electronic pen 105 to display characters and graphics input by the pen on a display screen of a liquid crystal display, so that a ball-point pen or the like is formed on paper. You can enter characters and figures as if you were writing with a writing instrument.

However, the above-mentioned display unit integrated tablet device has the following problems.

First, when the surface of the electrostatic induction tablet 101 is traced by the electronic pen 105 while looking at the display screen of the liquid crystal display, there is a problem that the display screen of the liquid crystal display is difficult to see. That is, as described above, the column electrode X and the row electrode Y of the electrostatic induction tablet 101
Is formed substantially transparently on a transparent substrate such as glass or plastic using tin oxide or indium oxide.

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 there is fogging. The electrodes are regularly arranged in a grid. Therefore, the electrode X _1, X ₂ of the electrostatic induction tablet _{101, ..., X m, Y} 1, Y 2, ..., Y n is noticeable beyond expectation. This phenomenon is particularly remarkable in a simple display unit integrated tablet without a backlight.

The electrodes X ₁ , X ₂ ,..., X _m , of the electrostatic induction tablet 101 are displayed on the display screen of the liquid crystal display.
The area covered by Y ₁ , Y ₂ ,..., Y _n is relatively large.
As a result, there is a problem that the display screen of the liquid crystal display is dark and the contrast is 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 stacked and assembled together, the liquid crystal display and the electrostatic induction tablet 101 are integrated. The position corresponding to the tablet 101 may be shifted.

In this case, the position of the pen input on the liquid crystal display (the position specified by the tip of the electronic pen 105) and the position of the pixel displayed on the display screen of the liquid crystal display due to the pen input are shifted. I will.
Therefore, there is a problem that characters and figures cannot be input as if writing with a writing implement such as a ballpoint pen on paper.

Furthermore, since the separately formed liquid crystal display and the electrostatic induction tablet 101 are integrally laminated, the resulting tablet with integrated display unit is large and heavy. Therefore, there is also a problem that it greatly hinders the miniaturization of small computers and word processors desired by consumers. In addition, there is a problem that the cost is increased.

Therefore, a first object of the present invention is to provide a display-integrated tablet device that is easy to see on a display screen when a position on the display screen is input with an electronic pen, and that is easy to reduce in size and cost. Is to provide.

Further, a second object of the present invention is to provide a display-integrated tablet device capable of simultaneously detecting the x-coordinate and the y-coordinate of the tip of the electronic pen when achieving the first object. is there.

Further, a third object of the present invention is to achieve the first object by preventing the inversion of the polarity of the induced voltage signal output from the electronic pen or preventing the erroneous detection of the induced voltage signal. An object of the present invention is to provide a display-integrated tablet device.

[0030]

According to a first aspect of the present invention, there is provided a display-integrated tablet device having a plurality of first electrodes and a plurality of second electrodes arranged along different directions. A display panel having a pixel corresponding to a location where the electrode and the second electrode intersect, an indication unit capacitively coupled to the first electrode and the second electrode to indicate a position on the surface of the display panel, and driving the first electrode A first electrode driving unit that drives the second electrode, a second electrode driving unit that drives the second electrode, and a voltage corresponding to each pixel by controlling the first electrode driving unit and the second electrode driving unit. Display control means for setting a display period in which a desired image is displayed by applying to the electrode ; first electrode driving means;
Controlling the first electrode or the second electrode by controlling the second electrode driving means;
And a scanning period for sequentially applying a scanning voltage to
Detection control means for measuring the time from the start of scanning, and a display period
The direction of application of voltage applied to each pixel is predetermined
First setting control means for switching and setting at intervals;
Second setting control means for setting the scanning voltage application direction between
And coordinate detection of the indicating means based on an induced voltage induced by the indicating means due to capacitive coupling of the scanning voltage applied by the indicating means and the detection control means and a time measured by the detection control means. a coordinate detection means for performing a first set
While switching between the constant control means and the second setting control means,
At the switching timing, the display control means and the detection
And switching control means for controlling switching between the control means and the control means.

The display-integrated tablet device according to the second aspect is characterized in that the display panel is a liquid crystal display panel.

According to a third aspect of the present invention, there is provided a display-integrated tablet device according to the first or second aspect , wherein the first electrode driver is used during the scanning period.
A first scan in which a scanning voltage is sequentially applied to a first electrode by controlling a stage;
The second electrode driving means is controlled following the scanning period and the first scanning period.
And a second scanning period in which a scanning voltage is sequentially applied to the second electrode.
Yes, an idle time is set between the first scanning period and the second scanning period.
And wherein the kick it.

According to a fourth aspect of the present invention, there is provided the display-integrated tablet device according to the third aspect , wherein the second setting control means sets the direction of application of the scanning voltage to be reversed during the idle time. It is characterized by controlling.

[0034]

According to a fifth aspect of the present invention, there is provided a display-integrated tablet device according to the first or second aspect , wherein the first setting control means switches the application direction of a voltage corresponding to each pixel. Timing is the second setting
Setting timing of the scanning voltage application direction by the control means;
Are asynchronous, the duty ratio of the switching timing by the first setting control means is 1, and the first
The last time in the voltage application direction by the setting control means and the first time in the voltage application direction by the first setting control means in the next display period have a complementary relationship.

The display-integrated tablet device according to the sixth aspect is the first, second, third, fourth and fourth aspects of the present invention.
The display-integrated tablet device according to claim 5 , wherein the coordinates detected by the coordinate detection means are displayed by the display control means.

According to a seventh aspect of the present invention, in the display-integrated tablet device according to the sixth aspect , the coordinate information detected by the coordinate detecting means is:
Subsequent display period is transferred to the display control means, further
The coordinate information is displayed on the display panel in a subsequent display period.

According to an eighth aspect of the present invention, there is provided the display-integrated tablet device according to the first or second aspect , wherein an applied voltage and an applied direction of each scanning voltage are constant during a scanning period . And setting the average DC voltage value of each pixel to zero.

According to a ninth aspect of the present invention, there is provided a display-integrated tablet device according to the first or second aspect, wherein at least four types of voltages are applied to the first electrode driving means and the second electrode driving means. comprising a voltage supply means for supplying, Oite the display period, voltages corresponding to each with respect to the one type of voltage of at least four kinds of voltages pixel according to the voltage application direction from the first setting control means And applying a scanning voltage during the scanning period based on any one of at least four types of voltages according to a voltage application direction from the second setting control means. I do.

According to a tenth aspect of the present invention, there is provided a display-integrated tablet device according to the first or second aspect, wherein the first electrode driving means and the second electrode driving means have V ₅ > V _4. > V ₃ > V ₂ > V ₁ > V ₀
Comprising a voltage supply means for supplying different voltages, and Oite <br/> the display period, a voltage corresponding to each pixel and (V ₅ -V _0), run
During the inspection period , the voltage between the first electrode and the second electrode is set to (V ₃
−V ₀ ) or (V ₅ −V ₂ ).

[0041] The display-integrated tablet device according to the eleventh aspect has a plurality of first electrodes and a plurality of second electrodes which are respectively arranged along different directions. , A display panel having pixels corresponding to the intersections, capacitively coupled to the first electrode and the second electrode, and instructing means for instructing the position of the display panel surface from the first electrode side, and driving the first electrode A first electrode driving unit, a second electrode driving unit for driving the second electrode, and a voltage corresponding to each pixel by controlling the first electrode driving unit and the second electrode driving unit; Display control means for setting a display period in which a desired image is displayed by applying the control signal to the first electrode and a first scanning period in which the first electrode driving means is controlled to sequentially apply a scanning voltage to the first electrode. Controls the second electrode driving means and sequentially runs to the second electrode A second control unit for setting a second scanning period for applying a voltage, and detecting control means for measuring a time from the start of scanning; and a capacitive coupling between the instruction means and the scanning voltage applied by the detection control means, to the instruction means. Coordinate detection means for detecting the coordinates of the indicating means based on the induced voltage induced and the time measured by the detection control means, and switching control for alternately controlling the display control means and the detection control means. Means, wherein the detection control means has an amplifier for amplifying the induced voltage induced by the indicating means, and the amplification factor of the amplifier of the induced voltage induced by the indicating means during the second scanning period is equal to the first. It is characterized in that it is larger than the amplification factor of the induced voltage induced by the indicating means during the scanning period.

According to a twelfth aspect of the present invention, there is provided a display-integrated tablet device having a plurality of first electrodes and a plurality of second electrodes arranged along directions different from each other. , A display panel having pixels corresponding to the intersections, capacitively coupled to the first electrode and the second electrode, and instructing means for instructing the position of the display panel surface from the first electrode side, and driving the first electrode A first electrode driving unit, a second electrode driving unit for driving the second electrode, and a voltage corresponding to each pixel by controlling the first electrode driving unit and the second electrode driving unit; Display control means for setting a display period in which a desired image is displayed by applying the control signal to the first electrode and a first scanning period in which the first electrode driving means is controlled to sequentially apply a scanning voltage to the first electrode. Controls the second electrode driving means and sequentially runs to the second electrode A second control unit for setting a second scanning period for applying a voltage, and detecting control means for measuring a time from the start of scanning; and a capacitive coupling between the instruction means and the scanning voltage applied by the detection control means, to the instruction means. Coordinate detection means for detecting the coordinates of the indicating means based on the induced voltage induced and the time measured by the detection control means, and switching control for alternately controlling the display control means and the detection control means. Means, wherein the peak value of the scanning voltage applied to the second electrode during the second scanning period is larger than the peak value of the scanning voltage applied to the first electrode during the first scanning period.

A display integrated tablet device according to a thirteenth aspect has a plurality of first electrodes and a plurality of second electrodes arranged along different directions, respectively, and the first electrode and the second electrode are connected to each other. A display panel having pixels corresponding to the intersections, an indication unit capacitively coupled to the first electrode and the second electrode, and indicating a position on the surface of the display panel; a first electrode driving unit for driving the first electrode; A second electrode driving means for driving the second electrode, and a voltage corresponding to each pixel is controlled by controlling the first electrode driving means and the second electrode driving means to thereby apply a desired image to the first electrode and the second electrode. A display control unit for setting a display period for displaying the image, a first scanning period for controlling the first electrode driving unit to sequentially apply a scanning voltage to the first electrode, and a second electrode driving unit following the first scanning period. Control to sequentially apply a scanning voltage to the second electrode And sets a second scan period,
Detection control means for measuring the time from the start of scanning, and an induced voltage induced by the indication means due to capacitive coupling between the indication means and the scanning voltage applied by the detection control means, and a time measured by the detection control means. A coordinate detecting means for detecting coordinates of the indicating means based on time; and a switching control means for alternately controlling the display control means and the detection control means, and applying a scanning voltage during a second scanning period. The number of second electrodes to be applied is larger than the number of first electrodes to which a scanning voltage is applied during the first scanning period.

A display-integrated tablet device according to a fourteenth aspect has a plurality of first electrodes and a plurality of second electrodes arranged at predetermined intervals along different directions, respectively.
A display panel having a pixel corresponding to a location where the first electrode and the second electrode intersect; an indication unit capacitively coupled to the first electrode and the second electrode to indicate a position on the display panel surface; , A second electrode driving unit for driving the second electrode, and a first electrode driving unit and a second electrode driving unit for controlling the first electrode driving unit and the second electrode driving unit to apply a voltage corresponding to each pixel to the first electrode and the first electrode driving unit. Display control means for setting a display period for displaying a desired image by applying to the second electrode; a first scanning period and a first scanning period for controlling the first electrode driving means to sequentially apply a scanning voltage to the first electrode Subsequently, the second electrode driving unit is controlled to set a second scanning period in which a scanning voltage is sequentially applied to the second electrode, and the detection control unit measures time from the start of scanning, and the first scanning period and High frequency components are superimposed on each scanning voltage in the second scanning period Frequency generation control means, and an induced voltage including a high-frequency component induced by the indication means due to capacitive coupling of the scanning voltage applied by the indication means and the detection control means, and a time measured by the detection control means. And a switching control means for alternately controlling the display control means and the detection control means.

According to a fifteenth aspect of the present invention, in the tablet device with an integrated display according to the fourteenth aspect , the high frequency generation control means controls the scanning voltage applied to the first electrode during the first scanning period. The first frequency of the high frequency component to be superimposed and the second frequency of the high frequency component to be superimposed on the scanning voltage applied to the second electrode during the second scanning period are set to be different from each other. Extracting means for separating and extracting the two frequencies from the induced voltage induced by the indicating means; detecting coordinates of the indicating means based on the extracted high-frequency component and the application timing measured by the detection control means; It is characterized by performing.

According to a sixteenth aspect of the present invention, in the tablet device with an integrated display according to the fifteenth aspect , the first frequency and the second frequency are set to frequencies other than odd multiples of each other. It is characterized by.

According to a seventeenth aspect of the present invention, there is provided a display-integrated bullet apparatus having a plurality of first electrodes and a plurality of second electrodes arranged at predetermined intervals along different directions. A display panel having a pixel corresponding to a location where the electrode intersects; an indication unit capacitively coupled to the first electrode and the second electrode, and indicating a position on the display panel surface;
A first electrode driving means for driving the first electrode, a second electrode driving means for driving the second electrode, and a voltage corresponding to each pixel by controlling the first electrode driving means and sequentially applying the voltage to the first electrode; A display control means for controlling a second electrode driving means to apply a voltage corresponding to each pixel to the second electrode to set a display period for displaying a desired image, and a first electrode in a display period corresponding to each pixel. High-frequency generation control means for superimposing a high-frequency component on the applied voltage, and a first means for measuring the application timing of each high-frequency component superimposed on the voltage corresponding to each pixel on the first electrode during a display period
A detection control unit, a second detection control unit for controlling a second electrode driving unit to set a scanning period for sequentially applying a scanning voltage to the second electrode, and timing application timing of each scanning voltage; Extracting means for extracting a high-frequency component from an induced voltage including a high-frequency component induced by the indicating means by capacitive coupling between the means and a high-frequency voltage applied by the first detection control means; and The application timing measured by the control means, the instruction means and the second
Coordinate detection for detecting the coordinates of the indicating means based on the induced voltage induced in the indicating means by capacitive coupling with the scanning voltage applied by the detection control means and the application timing timed by the second detection control means And switching control means for alternately controlling the display control means and the detection control means.

The display-integrated tablet device according to claim 18 is the display-integrated tablet device according to claim 12, claim 13, claim 14, claim 15, claim 16 , or claim 17 , The display panel is a liquid crystal display panel.

[0049]

According to the first aspect of the present invention, a display-integrated tablet device according to the present invention displays a desired image during a display period while scanning.
During the period, coordinate detection of pointing means such as an electronic pen
Out of the first setting control means and the second setting control means.
At the switching timing, the display control means and the detection control means
Is switched by the switching control means, the first setting control
Direction of voltage application by the stage and voltage by the second setting control means
No matter which direction the voltage is applied,
Unnecessary induced voltage induced in the indicating means by switching
It is possible to prevent occurrence and prevent erroneous detection during coordinate detection .

The display-integrated tablet device according to the present invention displays a desired image while switching the voltage application direction corresponding to each pixel at predetermined intervals in order to prevent the liquid crystal from deteriorating during the display period. A liquid crystal panel can be used as a display panel.

According to a third aspect of the present invention, there is provided a display-integrated tablet device according to the third aspect of the present invention, wherein the first scanning period and the second scanning period
By providing the idle time, it is possible to prevent interference between the induced voltage induced by the indicating means in the first scanning period and the induced voltage induced by the indicating means in the second scanning period.

According to a fourth aspect of the present invention, there is provided a display-integrated tablet device according to the third aspect of the present invention, wherein the direction of application of the scanning voltage by the second setting control means is changed during idle time in the display-integrated tablet device of the third aspect. By inverting, it is possible to prevent generation of an unnecessary induced voltage in the indicating means.

[0053]

According to a fifth aspect of the present invention, there is provided a display-integrated tablet device in which the switching timing of the voltage application direction of the first setting control means is asynchronous with that of the second setting control means as in a high-density liquid crystal panel. In the meantime, the scanning period may be entered while the desired image is being displayed on the display panel. Even in such a case, since the disturbance in the voltage application direction by the first setting control unit does not occur, a good display image can be obtained. Can be

The tablet device with integrated display of the present invention described in claim 6 can input characters and figures as if writing with a writing implement such as a pen on the display panel surface.

[0056] display-integrated type tablet device of the present invention according to claim 7, the transfer of the detected coordinate information is sequentially transferred, can be displayed with respect to the coordinate information.

[0057] The display-integrated type tablet device of the present invention according to claim 8, over the scan period, it is not necessary to perform complicated applied voltage and the direction of change control by leaving the applied voltage and application direction constant, Furthermore, by setting the average voltage value of each pixel to zero, the display panel can display liquid crystal
If the panel is used , deterioration of the liquid crystal can be prevented.

According to a ninth or tenth aspect of the present invention, in the display-integrated tablet device of the present invention, at least four types of voltages, preferably six types of voltages are applied to the first electrode driving means and the second electrode. This is realized by being supplied to the driving means.

According to an eleventh aspect of the present invention, there is provided a display-integrated tablet device according to the present invention, wherein the first electrode and the second electrode are designated by a pointing device such as an electronic pen. By setting the amplification factor of the amplifier that amplifies the induced voltage detected during the scanning period to be greater than the amplification factor of the amplifier that amplifies the induced voltage detected during the first scanning period, the induced voltage detected during each scanning period Can be made an appropriate size for binarization.

According to a twelfth aspect of the present invention, there is provided a display-integrated tablet device according to the present invention, wherein the first electrode and the back surface having the second electrode are designated by a pointing means such as an electronic pen. By making the average voltage value of the scanning voltage applied to the second electrode in the scanning period larger than the average voltage value of the scanning voltage applied to the first electrode in the first scanning period, the induced voltage detected in each scanning period can be reduced by two. It can be sized appropriately for valuation.

According to a thirteenth aspect of the present invention, there is provided a display-integrated tablet device according to the present invention, wherein the first electrode and the back surface having the second electrode, which are indicated by the indicating means such as an electronic pen, have the second electrode. By making the number of the second electrodes for applying the scanning voltage in the scanning period larger than the number of the first electrodes for applying the scanning voltage in the first scanning period, the induced voltage detected in each scanning period is binarized. It can be sized appropriately.

[0062] The display-integrated type tablet device of the present invention according to claim 14, since to perform the coordinate detection of the pointing means by superimposing a high frequency component in each scanning period, less affected by noise Become.

[0063] display-integrated type tablet device of the present invention as set forth in claim 15, first, the frequency of the second high-frequency component is set to be different from each other, performs the coordinate detection of the pointing means on the basis of their high-frequency components Therefore, it is possible to easily detect the coordinates in each scanning period without being affected by noise.

[0064] The display-integrated type tablet device of the present invention as set forth in claim 16, first, the frequency of the second high-frequency component is set other besides odd times together, the first high-frequency component or the second high-frequency As a result of the distortion of the components, even if the induced voltage includes other odd-numbered harmonic components, the coordinates can be detected in each scanning period without fail.

[0065] The display-integrated type tablet device of the present invention according to claim 17, in the display period, by superimposing a high-frequency component of the voltage applied sequentially for display on the first electrode by the high-frequency component, whereas , The display period in the frame can be lengthened.

The display-integrated tablet device according to the present invention described in claim 18 can use a liquid crystal panel as a display panel.

[0067]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

<First Example> FIG. 1 is a block diagram of a display-integrated tablet device according to a first example. This display-integrated tablet device is a display-integrated tablet device for achieving the first object, and uses electrodes and a drive circuit of an electrostatic induction tablet as electrodes and a drive circuit of a liquid crystal panel in a duty-type liquid crystal display device. By doing so, a tablet device with an integrated display function is configured.

Hereinafter, prior to the description of the display-integrated tablet device according to this embodiment, a duty-type liquid crystal display device will be briefly described.

FIG. 30 is a block diagram of a normal duty type liquid crystal display device. The liquid crystal panel 1 includes a transparent substrate in which a plurality of common electrodes Y ₁ , Y ₂ ,..., Y ₈ (hereinafter, an arbitrary common electrode is described as Y) and a plurality of segment electrodes X ₁ , A transparent substrate on which X ₂ ,..., X ₄₀ (hereinafter, an arbitrary segment electrode is described as X) is arranged in parallel, and a spacer or the like is arranged so that the common electrode Y and the segment electrode X face each other and are orthogonal to each other. They are arranged at a predetermined interval through. Liquid crystal is filled between the two transparent substrates.

In this way, the pixel is formed in a region where the common electrode Y and the segment electrode X intersect. That is, the liquid crystal panel 1 is driven by a duty type driving method while pixels of 40 dots × 8 dots are arranged in a matrix.

The common electrodes Y ₁ , Y ₂ ,..., Y ₈ are respectively connected to the corresponding output terminals 01, 02,.
It is connected to the. Then, the common electrode Y is activated by a selection pulse of the common electrode drive signal output from each of the output terminals 01, 02,..., 08 of the common drive circuit 2 to select a 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 01, 02,. Then, the output terminal 0 of the segment driving circuit 3
1,02, ..., segment from the 040 electrodes _{X 1, X 2, ...,} X 40
Outputs a segment electrode drive signal corresponding to the display data.

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. Further, the AC signal output terminal FR of the display control circuit 4 is connected 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 clock output terminal CP1 of the display control circuit 4 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 display control circuit 4
Is connected to the clock input terminal XCK of the segment drive circuit 3. 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 has a plurality of levels of bias power supply V used when the common drive circuit 2 and the segment drive circuit 3 generate a drive signal for driving the liquid crystal panel 1.
_{0 to} V ₅ are supplied to the common drive circuit 2 and the segment drive circuit 3. In the liquid crystal display device sets the bias power V ₀ ~V ₅ as follows.

That is, V ₀ = _0.0 V, V ₁ = 1.7 V, V
_{2 = 3.4V, V 3 = 23.5V} , V 4 = 25.2V, V 5 = 2
6.9V.

FIG. 31 is a diagram showing a terminal portion of the common drive circuit 2. As shown in FIG. Output terminals 01, 02, ..., the common electrode driving signal a from 08, b, ..., h is output, the common electrodes Y _1, Y ₂ corresponding liquid crystal panel 1, ..., is inputted to Y _8. The input terminals V0, V1, V4, and V5 are connected to a power supply circuit 5.
, The bias power supplies V ₀ , V ₁ , V ₄ , and V ₅ are input thereto. Based on the bias power supplies V ₀ , V ₁ , V ₄ , and V ₅ , the common electrode drive signals a, b,..., h are generated.

The duty-type liquid crystal display device having the above configuration operates as follows.

FIG. 32 is a timing chart of the common electrode drive signals ah and the segment electrode drive signals. The operation of the duty-type liquid crystal display device will be described below with reference to FIG. 32 with reference to FIGS.

When the clock signal cp1 output from the clock output terminal CP1 of 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. A pulse of shift data s output from the output terminal S is taken into a shift register (not shown) from the shift data input terminal DIO1. Then, selection pulses of the corresponding common electrode drive signals a to h are sequentially output from output terminals 01 to 08 corresponding to the pulse positions of the shift data s shifted by the shift register. At that time, the common electrode drive signals a to h are generated based on bias power supplies V _{0 to} V ₅ supplied from the power supply circuit 5.

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 driving circuit 3 synchronizes with the input clock signal cp2. , The designated position of the segment electrode X is shifted. Then, the data is output from the display data output terminals D0 to D3 of the display control circuit 4, and is output from the display data input terminal XD0 of the segment drive circuit 3.
~XD3 the display data D ₀ to D ₃ that is inputted to and sequentially read in the bit corresponding to the shift position in the register. Hereinafter, this operation is repeated 10 times, and the display data for one row (40 pixels) of the pixel matrix is taken into the register.

After that, the latch pulse input terminal XLP
In synchronism with the clock signal cp1 inputted display data D ₀ to D ₃ taken above is latched. And
Segment electrode drive signals corresponding to the latched display data D _{0 to} D ₃ are output from output terminals 01 to 040 to corresponding segment electrodes 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.

As described above, each pixel related to the common electrode Y ₁ selected and activated by the selection pulse (a) of the common electrode drive signal a output from the common drive circuit 2 is connected to the segment drive circuit 3. Is displayed in accordance with the display data by the segment electrode drive signal output from.

Hereinafter, the common electrodes Y ₂ , Y ₂ according to the selection pulses of the common electrode drive signals b to h from the common drive circuit 2
_3, ..., the Y ₈ are displayed sequentially selected by one frame of image, the next pulse of the shift data s is taken from the shift data input terminal DIO1 of the common drive circuit 2 again. Then, the above-described operation is repeated by the common drive circuit 2, the segment drive circuit 3, and the display control circuit 4, and an image for the next frame is displayed.

Hereinafter, this operation is repeated to repeat the operation of the liquid crystal panel 1.
The image is displayed on the screen.

[0087] That is, to display the image of the N-th frame during the period T ₁ in FIG. 32, the period subsequent T ₂
The image of the (N + 1) th frame is displayed during the period. In this case, the number of frames displayed per unit time is often set to about 72 frames / second so that flicker does not occur.

Generally, 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 Life is shortened. Therefore, in order to prevent this, the alternating current output from the alternating signal output terminal FR of the display control circuit 4 and input 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 are used. The application direction of the voltage applied to the liquid crystal is changed for each frame according to the level of the conversion signal fr.

The above-mentioned operation will be described in further 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
Has a waveform as shown in FIG. At that time,
It is assumed that the image of the Nth frame and the image of the (N + 1) th frame are the same image. As a result, each pixel in the liquid crystal panel 1 is displayed as shown in FIG.
In FIG. 33, ○ indicates a display pixel, while X indicates a non-display pixel.

The direction inversion of the voltage applied to the liquid crystal is performed as follows according to the level of the AC signal fr.

As shown in FIG. 32, when the level of the alternating signal fr is “L” (time T ₁ ), an arbitrary common electrode Y is activated to activate a display row in the pixel matrix of the liquid crystal panel 1. Are set to “V ₀ ” for the selection pulse voltage (hereinafter simply referred to as the selection voltage) of the common electrode drive signals a to h for selecting. On the other hand, the voltage (hereinafter, referred to as a non-selection voltage) of the common electrode drive signals a to h for inactivating any common electrode Y is “V ₄ ”. On the other hand, when the level of the alternating signal fr is “H” (time T ₂ ), the selection voltage is set to “V ₅ ”. On the other hand, the non-selection voltage is set to “V ₁ ”.

[0093] Further, in the case of level "L" of the alternating signal fr (for time T _1), the segment electrodes for displaying the display pixel of display rows above selected in the pixel matrix of the liquid crystal panel 1 The voltages of the drive signals A and B (ON voltage in FIG. 32) are set to “V ₅ ”. On the other hand, the voltages of the segment electrode drive signals A and B (off voltages in FIG. 32) for not displaying the non-display pixels of the selected display row are set to “V ₃ ”.
To

On the other hand, when the level of the AC conversion signal fr is “H” (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 pixels is set to “V ₂ ”.

The switching of the selection voltages “V ₀ ” and “V ₅ ” and the switching of the non-selection voltages “V ₄ ” and “V ₁ ” performed by the common drive circuit 2, and the switching by the segment drive circuit 3 Voltage “V ₅ ” applied to the display pixel,
The switching of “V ₀ ” and the switching of the applied voltages “V ₃ ” and “V ₂ ” to the non-display pixels are performed by an analog switch that operates in synchronization with the level change of the AC conversion signal fr. It is carried out by selecting one of the bias power supply V ₀ ~V _5.

As described above, in synchronization with the change of the level of the AC conversion signal fr between “L” and “H”, the selection voltages of the common electrode drive signals a to h are changed to “V ₀ ” and “V ₀ ” by the analog switch. "at the same time switching between the segment electrode drive signals a, the voltage applied to the display pixels in the B" V ₅ is switched between V ₀ "" and "V _5, and the common electrode Y in the display pixel The potential difference from the segment electrode X is (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 determined by the AC signal fr.
(V ₃ −V ₀ ), (V ₄ −V ₃ ),
(V ₅ −V ₄ ), which are both 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 AC conversion signal fr is "H", it becomes _one of (V ₁ -V ₀ ), (V ₂ -V ₁ ), and (V ₅ -V ₂ ). This is lower than the potential difference between the common electrode Y and the segment electrode X in the display pixel.

Accordingly, while the value of the potential difference (V ₅ −V ₀ ) becomes 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 ) by setting the value of the bias power supply V ₀ ~V ₅ to be less than, it is possible to perform the display of the liquid crystal Bunnell 1 regardless of the level of the AC signal fr.

At this time, since the direction of application 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, the life of the liquid crystal is prevented from being shortened. is there.

In the above description, the level of the alternating signal fr is inverted for each frame, so that the voltage application directions of the common electrode drive signal and the segment electrode drive signal are inverted. However, the number of pixels of the liquid crystal panel 1 increases, and in the case of a high-density liquid crystal panel such as 640 pixels × 400 pixels, the direction of the voltage between the common electrode Y and the segment electrode X is frequently changed (for example, Common electrode Y is 1
(Every time three rows are selected). In this case, since the total number of the common electrodes Y is 400, the frame switching period and the level inversion period of the alternating signal fr are not synchronized at all as shown in FIG.

Accordingly, the locations where the direction of the applied voltage is inverted in the image of one field are randomly dispersed, and there is an effect that brightness unevenness due to the application direction inversion of the voltage applied to the pixel is not observed at all.

[First Embodiment] Next, a display-integrated tablet device in this embodiment will be described.

As shown in FIG. 35, in the electrostatic induction tablet 101, the electrodes arranged in parallel in the vertical direction and the electrodes arranged in parallel in the horizontal direction face each other at a small interval. Also, as shown in FIG. 30, in the liquid crystal panel of the above-mentioned duty type liquid crystal display device, electrodes arranged in parallel in the vertical direction and electrodes arranged in parallel in the horizontal direction face each other at a small interval. I have.

Therefore, in this embodiment, focusing on this point, the row / column electrodes of the electrostatic induction tablet and the drive circuit of the row / column electrodes are connected to the common / segment in the liquid crystal panel of the duty type liquid crystal display device. The dual use of the electrode and the common / segment electrode drive circuit constitutes a display-integrated tablet device with an integrated display function.

As shown in FIG. 1, the display-integrated tablet device according to the present embodiment has a detection control circuit 6, a switching circuit 7, an x-coordinate detection circuit 8, and a y-coordinate detection circuit in a duty-type liquid crystal display device shown in FIG. 9, a control circuit 10 and an electronic pen 11 are added. The liquid crystal panel 1 also has the function of an electrostatic induction tablet.

Hereinafter, the liquid crystal panel 1 in which the function of the electrostatic induction tablet is integrated (that is, the electrostatic induction tablet in which the display function is integrated) is simply called a liquid crystal panel.

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 controlled based on the control of the control circuit 10.
The shift data s, the AC signal fr, the clock signal cp1, and the clock signal cp2 from the display control circuit 4 and the shift data sd, AC signal frd, the clock signal cp1d, and the clock signal cp2d from the detection control circuit 6 are switched and selected. Then, it outputs to the common drive circuit 2 and the segment drive circuit 3 as the shift data so, the AC conversion signal fro, the clock signal cp1o, and the clock signal cp2o.

Then, in the liquid crystal panel 1, when each signal from the display control circuit 4 is selected by the switching circuit 7, the common electrode drive signals a to h from the common drive circuit 2 and the segment drive circuit Based on the segment electrode drive signals A and B from 3, an image is displayed on the pixel matrix as described above.

On the other hand, when each signal from the detection control circuit 6 is selected by the switching circuit 7, the common electrode scanning signals y ₁ and y from the common drive circuit 2 output as described later in detail. _2, ..., y ₈ (hereinafter, an arbitrary common electrode scanning signal to as y) the segment electrode scanning signal x _1, x ₂ from the segment drive circuit 3, ..., x ₄₀ (hereinafter, an arbitrary segment electrode scanning Signal is denoted as x)
In order to detect the position of the tip of the electronic pen 11, the segment electrode X and the common electrode Y of the liquid crystal panel 1 are scanned as described above.

The x-coordinate detection circuit 8 and y-coordinate detection circuit 9 operate in substantially the same manner as the x-coordinate detection circuit 107 and y-coordinate detection circuit 108 in the drive section of the electrostatic induction tablet 101 shown in FIG. That is, the electronic pen 11
And the shift data s, output from the detection control circuit 6 to generate the segment electrode scanning signal x and the common electrode scanning signal y.
Based on the clock signal cp1 and the clock signal cp2,
The tip coordinates of the electronic pen 11 are detected.

At this time, a resistor having a high resistance value such as an oscilloscope probe is connected to the tip electrode of the electronic pen 11, or an operational amplifier 12 is connected when high precision is required. To increase the induced voltage at the tip electrode by increasing the impedance seen from the tip electrode side of the electronic pen 11, while lowering the impedance seen from the lead wire side so that external noise is not picked up by the lead wire. ing.

The tip electrode of the electronic pen 11 includes:
An induced voltage is always induced even when an image is displayed on the pixel matrix of the liquid crystal panel 1. However,
The x-coordinate detection circuit 8 and the y-coordinate detection circuit 9 operate only when each signal from the detection control circuit 6 is selected by the switching circuit 7 and the segment electrode X and the common electrode Y are scanned. The tip coordinates of the electronic pen 11 are detected.

The display-integrated tablet device having the above-described configuration operates as follows to execute image display on the pixel matrix and detection of the tip coordinates of the electronic pen 11.

FIG. 2 shows a display period during which an image is displayed on the pixel matrix of the liquid crystal panel 1 and coordinates at which the tip position of the electronic pen 11 is detected by scanning the segment electrode X and the common electrode Y of the liquid crystal panel 1. It is a timing chart with a detection period. In this display-integrated tablet device, one frame period is formed by a display period and a coordinate detection period. Further, the coordinate detection period is formed by the x coordinate detection period and the y coordinate detection period.

By doing so, the display of an image on the pixel matrix in the liquid crystal panel 1 and the liquid crystal panel 1
The detection of the coordinates of the tip of the electronic pen 11 by the electrostatic induction tablet can be performed without deteriorating the performance of each other.

In FIG. 2, the coordinate detection period is considerably long for easy understanding, but actually, the display period length / the coordinate detection period length is set to “5” or more. Switching between the display period and the coordinate detection period is performed by switching the switching circuit 7 between the display control circuit 4 side and the detection control circuit 6 side under the control of the control circuit 10.

In FIG. 2, the display period, the x-coordinate detection period, and the y-coordinate detection period are continuously performed for easy understanding. However,
Actually, an idle time is set between the display period and the x-coordinate detection period and between the x-coordinate detection period and the y-coordinate detection period.

The display period and the coordinate detection period (that is, x
The empty time is set between the coordinate detection period) and the following reason.

That is, as described above, in order to prevent the liquid crystal in the liquid crystal panel 1 from being decomposed due to electrolysis, the liquid crystal in the intersection region between the segment electrode X and the common electrode Y is determined based on the AC signal fro. Are simultaneously switched at a certain period in the direction of application of the voltage to be applied. At that time, a spike-like high voltage is induced at the tip electrode of the electronic pen 11.

The value of the induced voltage is at least one digit greater than the value of the voltage induced on the tip electrode of the electronic pen 11 due to each scanning signal during the coordinate detection period. In addition, since the timing of switching the application direction of the voltage applied to the liquid crystal is not synchronized with the frame period, the change in the application direction may occur immediately before the coordinate detection period in the display period. In this case, a high spike-like induced voltage is induced in the electronic pen 11 and sent to the operational amplifier 12 as it is.

However, since the value of the induced voltage input to the operational amplifier 12 is too high, the average level of the induced voltage becomes high. Even if the resulting induced voltage is input to the operational amplifier 12, it will not be correctly amplified. As a result, there arises a problem that the coordinate detection signal is not correctly binarized.

Then, in order to avoid such a problem,
An empty time is provided immediately after the display period without entering the coordinate detection period.

Further, the shift register of the segment drive circuit 3 immediately after the display period maintains the state when the segment electrode drive signal is input to each segment electrode X at the time of the last line display in the display period.
Therefore, it is necessary to perform pre-coordinate detection processing for clearing the contents of the shift register immediately before entering the coordinate detection period. For that purpose, it is necessary to provide an idle time between the display period and the x coordinate detection period.

On the other hand, the idle time is set between the x-coordinate detection period and the y-coordinate detection period because the induced voltage induced at the tip electrode of the electronic pen 11 and the y-time during the x-coordinate detection period
This is to prevent the induced voltages from interfering with each other during the coordinate detection period.

For example, the scanning start position in the x coordinate detection period on the liquid crystal panel 1 is on the left, while the scanning start position in the y coordinate detection period is on the top, and the electronic pen 1
Let us consider a case where the tip position of No. 1 is at the rightmost uppermost position. In this case, an induced voltage caused by the common electrode scanning signal y is generated immediately after an induced voltage caused by the segment electrode scanning signal x is generated at the tip electrode of the electronic pen 11.

However, since this induced voltage signal is an analog signal, the two voltage signals overlap and it is difficult to distinguish them. Therefore, the tip coordinate of the electronic pen 11 cannot be correctly detected by the x-coordinate detection circuit 8 and the y-coordinate detection circuit 9, and an erroneous coordinate value is detected.

Such erroneous detection of the coordinates of the tip of the electronic pen 11 can be prevented by providing an idle time between the x coordinate detection period and the y coordinate detection period.

In the display period, the switching circuit 7 controls the display control circuit 4 based on the control of the control circuit 10.
Shift data s, AC conversion signal fr, clock signal cp1,
The clock signal cp2 is selected and output as the shift data so, the alternating signal fro, the clock signal cp1o, and the clock signal cp2o.

Then, common drive circuit 2 and segment drive circuit 3 operate as described with reference to FIG. 30 to generate, for example, common electrode drive signals a to h and segment electrode drive signals A and B as shown in FIG. Output. As a result, each pixel of the pixel matrix of the liquid crystal panel 1 is displayed as shown in FIG.

Hereinafter, the operation of each circuit during the coordinate detection period, which is a feature of this embodiment, will be described in detail.

FIG. 3 shows the segment electrode scanning signal x output from the segment driving circuit 3 during the x coordinate detection period shown in FIG. 2 and the common electrode scanning signal y output from the common driving circuit 2 during the y coordinate detection period. Is shown. The generation of the segment electrode scanning signal x from the segment driving circuit 3 and the common electrode scanning signal y from the common driving circuit 2 during the coordinate detection period is performed by using the segment driving circuit 3 and the common driving circuit 2 for the common driving circuit 2 during the display period. This is possible by operating to function in the same way as the function.

However, at this time, the analog switch selects the bias power supplies V _{0 to} V ₅ in accordance with the level inversion of the AC conversion signal fro, and detects enough by the x-coordinate detection circuit 8 or the y-coordinate detection circuit 9. An induced voltage as much as possible is induced at the tip electrode of the electronic pen 11, and a segment electrode scanning signal and a common electrode scanning signal that do not display a liquid crystal are generated.

In this way, after the scanning pulse of the segment electrode scanning signal x is sequentially output from the segment driving circuit 3 to the corresponding segment electrode X, the scanning pulse of the common electrode scanning signal y from the common driving circuit 2 responds. When sequentially output to the common electrode Y, an induced voltage is induced at the tip electrode of the electronic pen 11 as described above. Then, the induced voltage signal from the electronic pen 11 is amplified by the operational amplifier 12 and then input to the x-coordinate detection circuit 8 and the y-coordinate detection circuit 9.

Then, the x-coordinate detection circuit 8 validates only the induced voltage signal input from the operational amplifier 12 during the x-coordinate detection period, while the y-coordinate detection circuit 9 receives the input during the y-coordinate detection period. The electronic pen 11 operates in the same manner as the x-coordinate detection circuit 107 and the y-coordinate detection circuit 108 in FIG.
The tip coordinates of are detected. Then, the x-coordinate detection circuit 8 outputs an x-coordinate signal representing the x-coordinate of the tip of the electronic pen 11, while the y-coordinate detection circuit 9 outputs a y-coordinate signal.

The output x-coordinate signal and y-coordinate signal are transferred to various processing units to perform various processes.

For example, image data representing the pen input position is written in an address based on the x coordinate signal and the y coordinate signal in an image memory (not shown). And
In the display period, the written image data representing the pen input position is the display data D _{0 to} D ₃ representing the pen input position.
The pixel at the pen input position on the liquid crystal panel 1 is displayed based on the read display data D _{0 to} D ₃ representing the pen input position. As a result, by tracing the liquid crystal panel 1 integrated with the electrostatic induction tablet function with the tip of the electronic pen 11, it is possible to input and display characters and figures as if writing with a writing instrument on paper.

The transfer of the x-coordinate signal and the y-coordinate signal from the x-coordinate detection circuit 8 and the y-coordinate detection circuit 9 to each of the processing units may be performed before the coordinate detection period in the next frame. Is suitably performed during the display period. Therefore, the pixel display of the pen input position on the liquid crystal panel 1 based on the x coordinate signal and the y coordinate signal obtained in the coordinate detection period of the Nth frame is performed in the display period of the (N + 2) th frame.

Next, the problems caused by integrating the function of the electrostatic induction tablet with the liquid crystal panel 1 and the countermeasures will be described in more detail.

First, during the coordinate detection period, the peak value Vd (see FIG. 3) of the scanning pulse in the segment electrode scanning signal x output from the segment driving circuit 3 and the common electrode scanning signal y output from the common driving circuit 2 is obtained. Is
There are the following restrictions. That is, in order to prevent the image quality of the image displayed on the pixel matrix of the liquid crystal panel 1 from deteriorating during the display period, the voltage applied to the liquid crystal of each pixel during the coordinate detection period exceeds the threshold value of the liquid crystal display voltage. Not be. Therefore, the value of the peak value Vd of the scanning pulse is determined by the common electrode Y and the segment electrode X.
The voltage between them must be set to be lower than the liquid crystal display voltage threshold.

The threshold value of the liquid crystal display voltage referred to here is as shown in FIG.
Is different from the threshold value of the liquid crystal display voltage in the display period described in the description. That is, the ratio of the coordinate detection period in one frame period is preferably as small as possible. Therefore, it is necessary to scan the common electrode Y and the segment electrode X at high speed during the coordinate detection period. Therefore, the threshold value of the liquid crystal display voltage during the coordinate detection period is the threshold value of the liquid crystal display voltage during high-speed scanning, and is slightly higher than the threshold value of the liquid crystal display voltage during the display period.

The peak value Vd of the scanning pulse in the case of the present embodiment is the bias power V ₀ supplied from the power supply circuit 5.
Set in the following manner by using the ~V _5.

For example, when the level of the AC conversion signal fro is "L", the setting is performed as follows. That is,
When scanning the segment electrodes X ₁ of the liquid crystal panel 1, a scanning segment electrodes X ₁ for the segment electrode scanning signal x ₁ of the scan pulse voltage (hereinafter, referred to as scan voltage) to "V _5"
And On the other hand, the segment electrode scanning signal x ₂ ~x ₄₀ of the voltage for the non-scan the segment electrodes X ₂ to X ₄₀ (hereinafter, referred to as non-scan voltage) to the "V _3". At this time, the voltages of all the common electrode scanning signals y are set to “V ₄ ”.

Then, the scanning segment electrode X ₁
When the potential difference between all of the common electrodes Y becomes (V ₅ -V _4). On the other hand, the potential difference between the non-scanning segment electrodes X ₂ to X ₄₀ and all the common electrodes Y becomes (V ₄ -V _3).

Therefore, if the values of the bias power supplies V _{0 to} V ₅ are set to be the same as those described with reference to FIG. 32, the voltages applied to the scanning pixels and the non-scanning pixels will be reduced during the display period. Becomes the same potential as the potential applied to
Naturally, the value is lower than the threshold value of the liquid crystal display voltage during the coordinate detection period and is not displayed.

The same applies to the case where the other segment electrodes X _{2 to} X ₄₀ are scanned, and the voltage applied to the scanning pixels and the non-scanning pixels is lower than the threshold value of the liquid crystal display voltage and is not displayed.

When scanning the common electrode Y ₁ , the scanning voltage is set to “V ₀ ”, while the non-scanning voltage is set to “V ₄ ”.
And At this time, the voltages of all the segment electrode scanning signals x are set to “V ₃ ”. Then, the voltage applied to the scanning pixel becomes (V ₃ −V ₀ ). On the other hand, the voltage applied to the non-scanning pixels is (V ₄ −V ₃ ).

Therefore, the voltages applied to the scanning pixels and the non-scanning pixels are lower than the threshold value of the liquid crystal display voltage during the coordinate detection period and are not displayed. Is exactly the same when scanning the other common electrodes Y ₂ to Y _8, it does not appear to scanned pixels and non-scanned pixels both.

On the other hand, when the level of the AC conversion signal fro is inverted to "H" as shown in FIG. 2, the scanning pulse peak value Vd is set as follows.

That is, when scanning the segment electrode X, the scanning voltage is set to “V ₀ ” and the non-scanning voltage is set to “V ₂ ”. At this time, the voltage of the common electrode scanning signal y is set to “V ₁ ”. Then, the voltage applied to the scanning pixel becomes (V ₁ −V ₀ ). On the other hand, the voltage applied to the non-scanning pixels is (V ₂ −V ₁ ).

Therefore, the voltage applied to the scanning pixel and the non-scanning pixel is lower than the threshold value of the liquid crystal display voltage during the coordinate detection period, and the image is not displayed.

When scanning the common electrode Y, the scanning voltage is set to “V ₅ ” and the non-scanning voltage is set to “V ₁ ”. At this time, the voltage of the segment electrode scanning signal x is set to “V ₂ ”. Then, while the voltage applied to the scan pixels is (V ₅ -V _2), the voltage applied to the non-scanning pixel becomes (V ₂ -V _1).

Therefore, the voltages applied to the scanning pixels and the non-scanning pixels are lower than the threshold value of the liquid crystal display voltage during the coordinate detection period and are not displayed.

As described above, in the coordinate detection period, the voltage applied to the scanning pixel and the non-scanning pixel is lower than the threshold value of the liquid crystal display voltage regardless of the level inversion of the AC signal fro. Do not show. Also,
At that time, the direction of the voltage applied to the scanning pixel and the non-scanning pixel is inverted with the level inversion of the AC conversion signal fro, so that the life of the liquid crystal is prevented from being shortened even during the coordinate detection period.

In the description of the generation of the segment electrode scanning signal x and the common electrode scanning signal y, the AC signal
The level inversion cycle of fro is synchronized with the frame cycle. However, in practice, as shown in FIG. 4, the level inversion cycle of the AC conversion signal fro and the frame cycle are asynchronous with each other to randomize the direction inversion point of the applied voltage in one frame image. As a result, since the time t _f from the last rising edge of the alternating signal fro for the periods as shown in FIG. 4 and the commencement of the coordinate detection period becomes random, the level of the alternating signal fr during the coordinate detection period inversion The places are also randomized.

FIG. 5 is a detailed diagram of the scanning signal waveform near the level inversion point when the level of the alternating signal fro is inverted at an arbitrary point during the coordinate detection period as described above.

When the display period shifts to the x-coordinate detection period, a pre-coordinate detection process is performed under the control of the control circuit 10 (see FIG. 1), and a shift register for shifting the shift data so of the common drive circuit 2 and a segment drive Circuit 3
Clear the contents of the latch circuit for latching the display data. After that, the x coordinate detection processing is started.
At this time, the level of the alternating signal fro is initially "L" and x
It is assumed that the signal is inverted to “H” during the coordinate detection period.

As can be seen from FIG. 5, when the level of the AC conversion signal fro is "L", the segment electrode scanning signal x
The scanning voltage is “V ₅ ”, while the non-scanning voltage is “V ₃ ”. The voltage of the common electrode scanning signal y is “V ₄ ”. This is because the level of the AC signal fro is inverted to “H”, so that the scanning voltage of the segment electrode scanning signal x becomes “V ₀ ”, the non-scanning voltage becomes “V ₂ ”, and the voltage of the common electrode scanning signal y becomes Changes to “V ₁ ”, and the voltage level decreases at the same time. For this reason, an induced voltage several times higher than a normal induced voltage induced during scanning of the segment electrode X is induced at the tip electrode of the electronic pen 11 which is coupled to the segment electrode X and the common electrode Y by a stray capacitance. . As a result, the x-coordinate detection circuit 8 erroneously detects the x-coordinate of the tip of the electronic pen 11 due to the induced voltage from the tip electrode of the electronic pen 11 due to the level inversion of the AC signal fro.

This also occurs when the level of the AC conversion signal fro is inverted from "H" to "L". Therefore, erroneous detection of the coordinates of the tip of the electronic pen 11 due to the level inversion of the AC signal fro occurs randomly. Therefore, the liquid crystal panel 1 does not function as a tablet in this state.

In order to solve the above-mentioned problem, in this embodiment, as shown in FIG. 6, the detected alternating-current signal fro during the coordinate detecting period is changed to the display alternating-current signal fro during the display period.
It is set independently. The detected AC conversion signal fro in the coordinate detection period is the AC conversion signal frd output from the detection control circuit 6. For example, the level inversion point is at a time other than the x coordinate detection period and the y coordinate detection period (for example, x (The boundary between the coordinate detection period and the y coordinate detection period). At this time, combinations of levels in the x-coordinate detection period and levels in the y-coordinate detection period are "HL", "HH", and "LL" in addition to "LH" shown in FIG. There may be.

Note that the display alternating signal fr in the display period is
o is an alternating signal fr output from the display control circuit 4
Is set to

As described above, in the present embodiment, during the display AC conversion signal fro in the display period based on the AC conversion signal fr from the display control circuit 4, the AC conversion signal frd from the detection control circuit 6 is used. The detection alternating signal fro in the coordinate detection period based on the signal is inserted. Therefore, it is not preferable to simply insert the detected alternating signal fro between the display alternating signals fro, since the direction inversion of the voltage applied to the liquid crystal during the display period is disturbed.

[0163] Therefore, as shown in FIG. 6, for example when switching to the coordinate detection period when the state of the level "H" of the display alternating signal fro has elapsed period t _f, the display period of the next frame the first level of the display switching signal fro the "H" in, the time t _b where _{t b = T f -t f,} T f: is taken as the level inversion period of the AC signal fro.

In the display period, the number of shifts of the shift register of the common drive circuit 2 (that is, the number of scans of the common electrode Y) is counted, and each time the count value becomes a value corresponding to the above _Tf , the display is performed. This can be realized by inverting the level of the AC conversion signal fro. Alternatively, the coordinate detection period is set to the period of the display alternating signal fro (2T
_f ) can be realized by setting it to an integral multiple of _f ).

As described above, the x coordinate detection period and y
When the combination of the levels of the detected alternating signal fro in the coordinate detection period and the level combination are always the same, the direction of the voltage applied to the liquid crystal in the x-coordinate detection period or the y-coordinate detection period is always the same, which is preferable. Absent. Therefore, the level of the detected alternating signal fro is inverted every frame. By doing so, x
The level of the detected alternating signal fro in the coordinate detection period or the y-coordinate detection period is reversed for each frame.

This is because the level of the detected alternating signal fro in the x-coordinate detection period in the immediately preceding frame and the level of the detected alternating signal fro in the y-coordinate detection period are stored in the memory, and the x-coordinate in the current frame is stored. This can be realized by reversing the levels of the detection alternating signal fro in the detection period and the y-coordinate detection period from the respective levels stored in the memory.

In this case, however, the polarity of the induced voltage induced at the tip electrode of the electronic pen 11 is inverted for each frame during the x coordinate detection period or the y coordinate detection period. Therefore, each coordinate cannot be stably detected by the x coordinate detection circuit 8 and the y coordinate detection circuit 9 as it is. Therefore, the induced voltage detected by the tip electrode of the electronic pen 11 is amplified and then full-wave rectified and input to the x-coordinate detection circuit 8 and the y-coordinate detection circuit 9. By doing so, the same x-coordinate detection circuit 8 and y-coordinate detection circuit 9 can stably detect the x-coordinate and y-coordinate of the tip of the electronic pen 11.

As described above, in the present embodiment, the detection control is applied to 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, a y coordinate detection circuit 9, a control circuit 10, and an electronic pen 11 are added. And
Each frame period is time-divided into a display period for displaying an image on the pixel matrix of the liquid crystal panel 1 and a coordinate detection period for detecting the tip coordinates of the electronic pen 11 on the liquid crystal panel 1.

In the display period, the control circuit 1
By the control of 0, the switching circuit 7 selects the display control circuit 4 side. The common drive circuit 2 and the segment drive circuit 3 are provided in accordance with the shift data so, the AC 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. Works.

At that time, the common electrode drive signals a to h generated by the common drive circuit 2 are input to the common electrodes Y _{1 to} Y ₈ of the liquid crystal panel 1, and the display columns of the pixel matrix of the liquid crystal panel 1 are sequentially arranged. Selected. On the other hand, indicated by the segment drive circuit 3 data D ₀ o~D ₃ o segment electrode drive signal A is generated based on, B liquid crystal panel 1
It is input to the segment electrode X ₁ to X _40, a pixel of the display columns selected by the common drive circuit 2 in the pixel matrix is displayed according to the display data.

In this way, the above-mentioned pixel matrix is shown in FIG.
It is displayed as shown in. On the other hand, in the coordinate detection period, the switching circuit 7 selects the detection control circuit 6 under the control of the control circuit 10. The common drive circuit 2 and the segment drive circuit 3 are provided 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 detection control circuit 6. Works.

Thus, the segment electrode scanning signals x _{1 to} x ₄₀ generated by the segment driving circuit 3 are applied to the segment electrodes X _{1 to} X ₄₀ of the liquid crystal panel 1, and the segment electrodes X are sequentially scanned. Then, an induced voltage is induced at the tip electrode of the electronic pen 11, and based on the induced voltage, the x-coordinate detection circuit 8 causes the electronic pen 11 to operate.
Is detected, and an x-coordinate signal is output.
Subsequently, the common electrodes Y ₁ of the common electrode scanning signal y ₁ ~y ₈ generated by the common drive circuit 2 is the liquid crystal panel 1
The common electrode Y is sequentially applied to Y ₈ to scan the common electrode Y. Then, based on the induced voltage induced on the tip electrode of the electronic pen 11, the y-coordinate
Is detected, and a y-coordinate signal is output.

At this time, the scanning of the segment electrode scanning signal x and the common electrode scanning signal y is performed so that the potential difference between the segment electrode X and the common electrode Y becomes smaller than the threshold value of the liquid crystal display voltage during the coordinate detection period. Since the pulse level is set, the liquid crystal panel 1 is set during the coordinate detection period.
Is not displayed.

The output x-coordinate signal and y-coordinate signal are converted into display data D _{0 to} D ₃ by the display control circuit 4 and output from the switching circuit 7 in accordance with the converted display data D _{0 to} D _3. The pixel at the tip position of the electronic pen 11 on the pixel matrix of the liquid crystal panel 1 is displayed based on the display data D _o o to D ₃ o.

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. In the display period, the liquid crystal panel 1 is used as an image display unit, and in the coordinate detection period, the liquid crystal panel 1 is used as a tablet, thereby forming a tablet having an integrated display function.

Therefore, according to the present embodiment, the brightness and contrast of the display screen of the display unit are reduced due to the low light transmittance of the row / column electrodes of the tablet, the regularity of the electrode arrangement of the tablet, and the display unit and the tablet unit. Problems such as a decrease in the visibility of the display unit due to a shift of the corresponding position, and an increase in size and cost due to lamination of the tablet and the display unit can be solved at once. That is, in the display-integrated tablet according to the present embodiment, the display screen is easy to see when inputting a position on the display screen with a pen, and it is easy to reduce the size and cost.

In this embodiment, the alternating signal fro for inverting the direction of application of the voltage applied to the liquid crystal of the liquid crystal panel 1 is set independently of the display period in the coordinate detection period. Therefore, the detected alternating signal fro in the coordinate detection period is changed to the x coordinate scanning period or y
It is possible to set so that the application direction of the voltage applied to the liquid crystal during the coordinate scanning period is not reversed. as a result,
It is possible to prevent erroneous detection of the tip position of the electronic pen 11 caused by a change in the voltage level of the common electrode scanning signal y or the segment electrode scanning signal x due to the level inversion of the detection alternating signal fro.

In the above embodiment, the liquid crystal panel 1
The AC signal fro for inverting the direction of application of the voltage applied to the liquid crystal of the display control circuit 4 and the detection control circuit 6
Is generated by However, the present invention is not limited to this, and may be generated by the common drive circuit 2 and the segment drive circuit 3 or the switching circuit 7, for example.

Further, the tip electrode of the electronic pen 11 may be composed of a plurality of electrodes, and the induced voltage from each of the electrodes may be differentially amplified by the operational amplifier 12. By doing so, the detection accuracy of the tip position of the electronic pen 11 can be further increased.

In the above embodiment, one set of the electronic pen 11, the operational amplifier 12, the x-coordinate detection circuit 8 and the y-coordinate detection circuit 9 is provided. However, the present invention is not limited to this.
A plurality of sets of the electronic pen 11, the operational amplifier 12, the x-coordinate detection circuit 8, and the y-coordinate detection circuit 9 may be provided so that pen input can be independently performed by a plurality of electronic pens.

At this time, if each of the characters and figures input by the respective electronic pens is displayed in a different line type (for example, a solid line, a dotted line, a bold line, etc.) or in a different color, it is possible to draw with different electronic pens. Characters and figures can be easily distinguished.

Also, in the above embodiment, by adding a means for recognizing an input character or figure, a character or figure input by a pen is recognized by the above-mentioned recognition means, and various processes are carried out using the recognition result. It is also possible.
Alternatively, an instruction determining means is added to determine the content of the processing menu instructed by the electronic pen among the various processing menus (so-called icons) displayed on the liquid crystal panel 1 and execute the processing according to the determination result. It is also possible.

As a display unit-integrated tablet device widely used at present, there is one in which an electromagnetic induction type tablet is superimposed on the back surface of a liquid crystal panel. In this electromagnetic induction type tablet, the induced voltage induced on the electrodes of the electromagnetic induction type tablet by the high frequency magnetic field from the tip of the detection pen is detected to determine the coordinates of the tip of the detection pen. Therefore, erroneous detection is easily caused by the influence of a slight external magnetic field.

For this reason, when a printed circuit board on which a CPU (Central Processing Unit), an IC memory, and the like are mounted is installed on the back of the electromagnetic induction type tablet, an external magnetic field generated by a current flowing through a circuit on the printed circuit board is set. , The coordinates of the tip of the detection pen are erroneously detected.

On the other hand, in the above embodiment, the segment electrode X and the common electrode Y are not affected by an external magnetic field. Therefore, a CPU, an IC memory, or the like can be directly arranged on the back surface of the liquid crystal panel 1,
Even if the printed circuit board on which the memory is mounted is placed almost in close contact with the back surface of the liquid crystal panel 1, there is no problem in detecting the tip coordinates of the electronic pen 11.

Therefore, if the above-described recognition means, instruction determination means, and other processing means are constituted by the CPU provided on the back surface of the liquid crystal panel 1 in this manner, a pen input can be performed instead of a keyboard. An extremely thin small computer using input can be realized. Furthermore, if a polymer dispersed liquid crystal is adopted as the liquid crystal used for the liquid crystal panel 1, a flexible sheet tablet can be formed, and a notebook computer can be realized. Become.

[Second Embodiment] In the coordinate detection period in the above embodiment, the segment electrodes X and the common electrodes Y are sequentially scanned one by one. By the way, in the case of a high-density liquid crystal panel, the number of each electrode is increased and the thickness of the electrode is correspondingly reduced. Then, the stray capacitance that couples the electrodes X and Y to the tip electrode of the electronic pen 11 becomes small, and the induced voltage induced at the tip electrode of the electronic pen 11 becomes extremely low. That is, this causes erroneous detection of the tip position of the electronic pen 11.

Therefore, in this embodiment, as described below, the tip position of the electronic pen 11 can be reliably detected even in a high-density liquid crystal panel.

FIG. 7 is a timing chart of the segment electrode scanning signal x and the common electrode scanning signal y during the coordinate detection period in this embodiment. The setting of the level and timing of the segment electrode scanning signal x and the common electrode scanning signal y and the control of the inversion of the voltage direction in this embodiment are the same as those described in the above embodiment. However, in the present embodiment, the segment electrode scanning signal x or the common electrode scanning signal y is applied collectively to the plurality of segment electrodes X or the plurality of common electrodes Y.

[0190] That is, in FIG. 7, the segment electrode scanning signal x _a is a present segment electrodes X _1, X _2, ..., are collectively applied to the X _a. Also, the segment electrode scanning signal x
_2a is collectively applied to a segment electrodes X _{a + 1} , X _{a + 2} ,..., X _2a . In the same manner, the segment electrode scanning signal x _m segment electrode X _{m-a + 1} of a present, ..., is being applied collectively to X _m.

[0191] On the other hand, the common electrodes Y ₁ of the common electrode scanning signal y _b is b present, Y _2, ..., are collectively applied to the Y _b. Also,
The common electrode scanning signal y _2b is composed of b common electrodes Y _{b + 1} , Y
_{b + 2} ,..., X _2b are applied collectively. Similarly,
Common electrodes Y _{n-b + 1} of the common electrode scanning signal y _n is b present, ...,
X _n is applied collectively.

In order to simultaneously apply a scanning signal to the plurality of electrodes at once, the following method may be used. That is, the shift data s output from the detection control circuit 6
d, the clock signal cp1d, a scan pulse of the clock signal cp2d and the data signal D ₀ d~D ₃ d such as the scanning signal generated based on, can be achieved by latching a time period corresponding to each electrode in the latch circuit.

As described above, by scanning a segment electrodes X and b common electrodes Y collectively, the induced voltage induced at the tip electrode of the electronic pen 11 can be increased. Therefore, according to the present embodiment, erroneous detection of the position of the tip of the electronic pen 11 when the high-density liquid crystal panel is used as an electrostatic induction tablet having an integrated display function is eliminated.

By scanning a segment electrodes X and b common electrodes Y collectively, the following effects can be obtained. That is, the clock signal cp1d and the clock signal cp2d output from the detection control circuit 6
However, even if the signal has the same cycle as when each electrode is scanned one by one, the scanning speed of the segment electrode X becomes a times, and
The scanning speed of the common electrode Y becomes b times. Therefore, the display period can be sufficiently secured by shortening the coordinate detection period, and the display on the high-density liquid crystal panel can be dealt with.

As in the case of this embodiment, when the a segment electrodes X and the b common electrodes Y are scanned together, the actual pitch of the segment electrodes X or the common electrodes Y in the scanning unit is about several mm. It becomes big. Therefore, there is a concern that the detection accuracy of the tip position of the electronic pen 11 is reduced.

However, by scanning several electrodes collectively as described above, the waveform of the induced voltage induced at the tip electrode of the electronic pen 11 becomes closer to that shown in FIG.
When scanning is performed one by one, the waveform becomes closer to that shown in FIG. Therefore, as described in the description of FIG. 37,
After the peak value of each step is normalized by the maximum peak value, the tip coordinates of the electronic pen 11 are obtained based on the ratio between the maximum peak value and the second highest peak value, thereby realizing the actual pitch of the electrodes in scanning units. However, the tip position of the electronic pen 11 can be detected with a resolution of about 8 dots / mm.

The obtained induced voltage having a waveform as shown in FIG. 37A is shaped into a waveform as shown in FIG. 37B through a low-pass filter, and after the scanning is started, the waveform shown in FIG. It is also possible to detect the position of the tip of the electronic pen 11 based on the time Ts until the peak of the waveform is detected. In such a case, comparators are provided in the x-coordinate detection circuit 8 and the y-coordinate detection circuit 9, and the comparators shown in FIG.
The coordinate detection signal of the analog waveform shown in FIG. 7B is binarized as shown in FIG. Then, the time Tr and the time Tg from the start of the scanning are measured, and the time Ts shown in FIG. 37B is calculated by the following equation.

Ts = (Tr + Tg) / 2 At this time, the measurement of the time Tr and the time Tg is based on the time from the start of scanning to the rise or fall of the pulse in FIG. What is necessary is just to measure by the counter built in the detection circuit 8 or the y-coordinate detection circuit 9. At this time, in order to improve the measurement accuracy, the count clock frequency of the counter is set to the clock signal cp1d (scanning clock of the common electrode Y) and the clock signal cp2d (segment electrode X) from the detection control circuit 6.
Is set to a value higher than the frequency of the scan clock.

As described above, in this embodiment, the segment electrode scanning signal x or the common electrode scanning signal y is applied to the plurality of segment electrodes X or the plurality of common electrodes Y.
Are applied collectively. Therefore, according to the present embodiment, the induced voltage induced at the tip electrode of the electronic pen 11 can be increased, and a high-density liquid crystal panel is used as an electrostatic induction tablet having an integrated display function. However, the tip coordinates of the electronic pen 11 can be correctly detected. Further, the segment electrode scanning speed or the common electrode scanning speed can be increased.

FIG. 8 shows an embodiment in which the same effect as when scanning a plurality of electrodes at a time is obtained by performing electrode scanning one by one in the coordinate detection period (only the common electrode scanning signal y is described). In this embodiment, as shown in FIG. 8, the common electrode scanning signal y is sequentially applied to the common electrode Y based on the clock signal cp1d from the detection control circuit 6, as shown in FIG. However, in the case of the present embodiment, the scanning pulse application time Tp is set to a plurality of cycles of the clock signal cp1o or the clock signal cp2o. As a result, at a certain point in time, scanning pulses of different common electrode scanning signals y are simultaneously applied to the plurality of common electrodes Y. By doing so, the induced voltage induced at the tip electrode of the electronic pen 11 is induced by more scanning voltages of the common electrode Y, so that the induced voltage can be increased, and the detection accuracy of the tip position of the electronic pen 11 can be improved. Will be better.

However, in this case, the waveform of the induced voltage induced on the tip electrode of the electronic pen 11 is closer to that shown in FIG. 37B, and in this embodiment, the tip position of the electronic pen 11 is determined based on the time Ts. Should be detected.

This method is effective when used in the case of the common drive circuit 2 according to the above-described embodiment, in which a plurality of scans cannot be performed because a latch circuit is not built in. However, it can be used for scanning the segment electrodes without any problem.

In the second embodiment, as shown in FIGS. 7 and 8, the scanning voltage of the common electrode scanning signal y is
Is set to a voltage higher than the non-scanning voltage, contrary to the case of the first embodiment shown in FIG. However, this merely changes the polarity of the induced voltage induced at the tip electrode of the electronic pen 11, and there is no particular problem.

[Third Embodiment] In the embodiment described below, noise superimposed on the induced voltage induced at the tip electrode of the electronic pen 11 is removed, and erroneous detection of the tip position of the electronic pen 11 is performed. To prevent.

In FIG. 9, a rectangular wave having a high frequency is inserted at a scanning pulse portion (hereinafter, referred to as a scanning period) of the segment electrode scanning signal x or the common electrode scanning signal y as shown in FIG. 3 or FIG. It is. Electronic pen 11
Since an induced voltage is induced at the tip electrode of the segment electrode by capacitive coupling with the segment electrode X and the common electrode Y, the scanning period of the segment electrode scanning signal x or the common electrode scanning signal y is changed at a high frequency, so that the electronic pen is changed. The induced voltage induced at the eleven tip electrodes increases and includes high frequency components.

The induced voltage induced at the tip electrode of the electronic pen 11 passes through an amplifier that passes and amplifies only high-frequency components, and then rectifies to obtain a signal having a waveform as shown in FIG. A ceramic filter or the like is effective as a filter that passes only a specific frequency component used at that time.

According to the method of applying each scanning signal in each of the above-described embodiments, the tip position of the electronic pen 11 is caused by static noise from the outside or noise due to charging due to friction between the electronic pen 11 and the tablet surface or the like. Erroneous detection occurs. However, according to the scanning signal application method as in the present embodiment, the signal from the electronic pen 11 input to the x coordinate detection circuit 8 or the y coordinate detection circuit 9 includes the segment electrode scanning signal x or the common electrode scanning signal. Since a specific frequency component caused by y is superimposed, only a signal necessary for coordinate detection can be efficiently amplified and separated from noise.

In implementing this embodiment, it is necessary to select a frequency (for example, 500 KHz) that does not generate a high frequency inserted into the liquid crystal element during the scanning period of the scanning signal.

In the above embodiment, a high-frequency rectangular wave is inserted during the scanning period of the electrode scanning signal. However, the present invention is not limited to this. FIG. 10 shows an example of inserting a high frequency sine wave. According to the present embodiment, the segment electrode X
Alternatively, since an AC waveform is applied to the common electrode Y, there is an effect that the electrolysis of the liquid crystal during the coordinate detection period can be prevented in addition to the effect of the above embodiment.

The scanning signal in which a high-frequency sine wave is inserted during such a scanning period is provided with a high-frequency power supply separately from the power supply circuit 5 in FIG. 1, and an alternating current from the high-frequency power supply is selected by an analog switch to perform common driving. It is obtained by inputting to the power supply input terminals of the circuit 2 and the segment drive circuit 3.

[Fourth Embodiment] In each of the above embodiments, in the x coordinate detection period of the coordinate detection period, the segment electrode X
, The scanning pulse of the common electrode scanning signal y is sequentially applied to the common electrode Y during the y coordinate detection period.
The tip coordinates of are detected. However, even in the display period, selection pulses of the common electrode drive signals a to h are sequentially applied to the common electrode Y in units of one. Therefore, the y coordinate detection operation in each of the above embodiments can be performed not in the y coordinate detection period but in the display period.

In this embodiment, the y-coordinate detecting operation is performed during the display period as described in detail below.

As described above, the selection pulse of the common electrode drive signals a to h is applied to the common electrode Y one by one during the display period. However, as described above, a segment electrode drive signal having a voltage corresponding to the content of the display data is applied to all the segment electrodes X at a time. For example,
In the timing chart shown in FIG. 32, the segment electrode drive signal A indicates that the odd-numbered segment electrodes X ₁ , X ₃ ,
Are simultaneously applied to the even-numbered segment electrodes X ₂ , X ₄ ,...

Accordingly, an induced voltage caused by the common electrode drive signals a to h and an induced voltage caused by the segment electrode drive signals A and B are simultaneously induced on the tip electrode of the electronic pen 11. In this case, it is not possible to specify which drive signal is the induced voltage induced in the tip electrode, and it is not possible to detect the tip coordinates of the electronic pen 11.

Therefore, in the present embodiment, the induced voltage caused only by the common electrode drive signals a to h is separately detected as follows.

FIG. 11 shows the waveforms of the common electrode drive signals a to h according to the present embodiment. In this embodiment, a high frequency is superimposed on the selection pulses of the common electrode drive signals a to h. In this embodiment, the high-frequency voltage value superimposed on the selection pulse is about 5V. Such a high frequency hardly affects a liquid crystal display having a slow response speed.

The induced voltage signal induced at the tip electrode of the electronic pen 11 by the common electrode drive signals ao to ho in which the high frequency component is superimposed on such a selection pulse and the ordinary segment electrode drive signals A and B is filtered. Only high-frequency components are extracted by passing through. Therefore, the y coordinate detection circuit 9
Is a signal in which only the induced voltage based on the common electrode drive signals ao to ho is separated.

As described above, according to the present embodiment, the y coordinate of the tip of the electronic pen 11 can be accurately detected during the display period.

In this embodiment, the x-coordinate of the tip of the electronic pen 11 is detected by providing an x-coordinate detection period between display periods as shown in FIG. What is necessary is just to detect based on the segment electrode scanning signal x similarly to the case of an Example. In this case, since the y-coordinate detection period is not required, the coordinate detection period can be shortened, and the display period can be sufficiently ensured.

Further, an electrostatic induction tablet having only the row electrodes X is laminated on the liquid crystal panel of the duty type liquid crystal display device in this embodiment, and the x coordinate of the tip of the electronic pen 11 is detected by the electrostatic induction tablet. On the other hand, the y coordinate may be detected by a liquid crystal panel.

An embodiment in which a high-frequency rectangular wave is inserted during the scanning period of the above-described segment electrode scanning signal x or the common electrode scanning signal y, or a high-frequency sine wave during the scanning period of the segment electrode scanning signal x or the common electrode scanning signal y In any of the embodiments using the common electrode drive signal ao to ho in which the high frequency is superimposed on the selection pulse or the embodiment using the common electrode drive signal ao to ho, By changing the phase for each electrode group and detecting this phase, it is possible to detect the tip position of the electronic pen 11 with higher accuracy.

The frequency of the high frequency added to the pulse may be changed for each electrode or for each electrode group.

[Fifth Embodiment] The following embodiments are embodiments that can further enhance the effects of the above embodiments.

As shown in FIG. 1, the liquid crystal panel has a structure in which a lower common electrode Y and an upper segment electrode X intersect at a predetermined interval. Therefore, the distances between the common electrode Y and the segment electrode X constituting the same pixel and the tip electrode of the electronic pen 11 are different. Therefore, when a scanning pulse having the same peak value is applied to the common electrode Y and the segment electrode X, the induced voltage caused by the common electrode Y far from the tip electrode of the electronic pen 11 exhibits a lower voltage. This is because the common electrode Y is shielded by the segment electrode X.

However, as described above, the peak value Vd of the scanning pulse of the scanning signal is limited because of the relationship with the threshold value of the liquid crystal display voltage, so that it cannot be set freely. Therefore,
The electrode to which the higher one of the peak value Vd of the scan pulse in the segment electrode scan signal x and the peak value Vd of the scan pulse in the common electrode scan signal y is applied is disposed below.

In this way, the induced voltage caused by the segment electrode scanning signal x and the induced voltage caused by the common electrode scanning signal y can be easily made substantially equal.

In this embodiment, the position of the common electrode Y where the peak value Vd of the scanning pulse of the applied scanning signal is higher is lower than the position of the segment electrode X where the peak value Vd of the scanning pulse is lower. On the side. The peak value Vd of the scanning pulse in this case is “V ₅ −V ₃ ” in the case of the segment electrode scanning signal x ₁ in FIG. 5, and “V ₂ −V ₃ ” in the case of the segment electrode scanning signal x _{5. 0} ".

As another embodiment in which the induced voltage caused by the segment electrode scanning signal x and the induced voltage caused by the common electrode scanning signal y can be made substantially equal, there is the following method.

That is, the same scanning signal is applied to a plurality of electrodes as shown in FIG. 7 or the same scanning is applied to a plurality of electrodes by applying a scanning signal to each electrode as shown in FIG. In an embodiment in which the same effect as when a signal is applied is obtained, the number of electrodes to which the same scanning pulse is applied (or the scanning pulse application time Tp) is set to be larger on the lower electrode side.

By doing so, it is possible to increase the induced voltage caused by the scanning signal applied to the lower electrode.

A method of increasing the peak value of the scanning pulse applied to the lower electrode and a method of setting the number of electrodes to which the same scanning signal is applied to a larger value on the lower scanning electrode side are described. Anything can be used together.

[Sixth Embodiment] In the fifth embodiment,
The method of increasing the peak value of the scanning pulse of the scanning signal applied to the electrode located on the lower side, or the method of setting the number of electrodes to which the same scanning signal is applied to the electrode located on the lower side to be larger, The value of the induced voltage caused by the scanning signal applied to the electrode located at the position is increased.

On the other hand, in this embodiment, even if the peak value of the scanning pulse of the segment electrode scanning signal x and the peak value of the scanning pulse of the common electrode scanning signal y are the same,
This is an embodiment in which the x coordinate and the y coordinate of the tip of the electronic pen 11 can be detected with the same accuracy.

That is, in this embodiment, instead of making the peak value Vd of the scan pulse of the segment electrode scan signal x and the peak value Vd of the scan pulse of the common electrode scan signal y the same, the lower electrode (In this embodiment, the amplification factor of the induced voltage caused by the scanning signal of the common electrode Y) is higher than the amplification factor of the induced voltage caused by the scanning signal of the upper electrode (in this embodiment, the segment electrode X). Make it bigger.

That is, first, the induced voltage signal caused by the segment electrode scanning signal x and the common electrode scanning signal y
Of the induced voltage signal caused by the
The signal is amplified by the amplifier 12 at the same amplification rate. The amplification factor at this time is a voltage suitable for binarizing an induced voltage caused by the segment electrode scanning signal x (scanning signal for the electrode located on the upper side) by a comparator built in the x coordinate detection circuit 8. (For example, 2 V to 5 V) is set to an amplification factor (100 times in this embodiment). In this case, the amplified voltage resulting from the common electrode scanning signal y (scanning signal related to the lower electrode) is converted into a binary value by a comparator built in the y-coordinate detection circuit 9. Voltage is not good (for example,
0.5V or less).

Thereafter, the induced voltage resulting from the segment electrode scanning signal x is binarized by the comparator of the x coordinate detection circuit 8.

At this point, as described above, the value of the induced voltage due to the common electrode scanning signal y is still too low for binarization, and therefore, the voltage is further amplified by the amplifier built in the common electrode detection circuit 9. (In the embodiment, it is amplified 10 times.)
You do it. In that case, the segment electrode scanning signal x
When the induced voltage signal caused by the input segment electrode scanning signal x is too large, the average level of the induced voltage is increased and the essential common electrode scan is performed. The induced voltage caused by the signal y is not correctly amplified. Therefore, the induced voltage signal is input to the built-in amplifier only during the y-coordinate detection period by an analog gate circuit or the like.

The amplification of the induced voltage may be performed as follows. That is, the x-coordinate detection circuit 8 and the y-coordinate detection circuit 9 are provided with an amplifier having an amplification factor of 100 and an amplifier having an amplification factor of 1000, respectively. Further, the analog gate circuit enables a path for inputting the induced voltage signal from the electronic pen 11 to the amplifier to be switched between a path passing through the amplifier having the amplification factor of 100 times and a path passing through the amplifier having the amplification factor of 1000 times. . Then, during the x-coordinate detection period, the above path is switched to the amplifier side having the amplification factor of 100, while in the y-coordinate detection period, the path is switched to the amplifier side having the amplification factor of 1000.

Seventh Embodiment In each of the above embodiments, the coordinate detection period is provided after the display period of the Nth frame for the sake of simplicity. However, the present invention is not limited to this, and the coordinate detection period may be inserted during the display period of the Nth frame.

In this case, during the display period for displaying the image of the N-th frame, the switching circuit 7 switches the detection control circuit 6 according to the control of the control circuit 10 in FIG.
When the side is switched and selected to switch to the coordinate detection period, the display control circuit 4 stores the display data and the state of various display control signals at that time. When the switching circuit 7 switches and selects the display control circuit 4 and the display period of the Nth frame is restarted, the display of the Nth frame is restarted based on the state of each stored signal. I just need.

In this case, the insertion position of the coordinate detection period in one display screen need not always be the same position. For example, in the case of a liquid crystal matrix of 400 dots × 640 dots, a coordinate detection period is inserted every 321 lines. In this case, the frame cycle and the coordinate detection period insertion cycle are asynchronous. Therefore, the switching point from the display period to the coordinate detection period moves randomly in one display screen, and the influence of the coordinate detection period on the display period is reduced.

It is also possible to make the number of insertions of the coordinate detection period per second larger than the number of frame periods per second.

<Second Example> By the way, in order to increase the display period in one frame period in the liquid crystal display and improve the display efficiency, it is necessary to shorten the coordinate detection period as much as possible. However, in the display-integrated tablet device of the first example, as shown in FIG. 2, the coordinate detection period is formed by the x coordinate detection period and the y coordinate detection period, and the x coordinate detection and the y coordinate detection are performed separately. During the period. Therefore, there is a limit in shortening the coordinate detection period.

Therefore, in the second example, the x-coordinate detection and the y-coordinate detection are performed at the same time, so that the coordinate detection period is reduced to almost half at a stroke. That is, the display-integrated tablet device in the second example is a display-integrated tablet device for achieving the second object.

[Eighth Embodiment] FIG. 12 is a block diagram of a display-integrated tablet device according to this embodiment. This display-integrated tablet device is different from the configuration of the display-integrated tablet device shown in FIG. 1 in the first example in that a high-frequency power supply circuit 21 for generating two high-frequency voltage signals Vfx and Vfy having different frequencies, and an operational A band-pass filter (hereinafter abbreviated as BPF (fx)) 22 that allows only components having the same frequency as the frequency of the high-frequency voltage signal Vfx to pass through among the induced voltage signals output from the amplifier 12.
And a BPF (fy) 23 for passing only a component having the same frequency as the frequency of the high-frequency voltage signal Vfy among the induced voltage signals output from the operational amplifier 12.

In FIG. 12, the same components as those in FIG. 1 are denoted by the same reference numerals as those in FIG.

The high frequency voltage signal Vfx and the high frequency voltage signal Vfy may be high frequency pulse signals (hereinafter simply referred to as pulse signals) or high frequency sine wave signals (hereinafter simply referred to as sine wave signals). You may.

A DC component may be added to these pulse signals or sine wave signals. However, in this case, if a potential difference occurs in the liquid crystal layer, the liquid crystal deteriorates. Therefore, it is preferable that the DC component voltages of the high-frequency voltage signal Vfx and the high-frequency voltage signal Vfy are equal to each other.

The common drive circuit 2 has a high frequency voltage signal input terminal VFY to which the high frequency voltage signal Vfy from the high frequency power supply circuit 21 is input. The segment drive circuit 3 has a high-frequency voltage signal input terminal VFX to which the high-frequency voltage signal Vfx from the high-frequency power supply circuit 21 is input.

As the common drive circuit 2 and the segment drive circuit 3, the high-frequency voltage signal input terminals VFY,
When the common drive circuit 2 and the segment drive circuit 3 shown in FIG. 1 having no VFX are used as they are, the DC power supplied from the power supply circuit 5 is not provided without providing the high-frequency power supply circuit 21 as in the first embodiment. Bias power supply V
₀ ~V may be to generate the pulse signal on the basis of _5.

FIG. 13 shows the high-frequency voltage signals Vfx and Vfy.
By using the pulse signal as described above, the segment electrode X and the common electrode Y are formed by the segment electrode scanning signal x in which the pulse signal Vfx is inserted in the scanning period and the common electrode scanning signal y in which the pulse signal Vfy is inserted during the scanning period. 5 is a timing chart of a coordinate detection period when scanning is performed simultaneously.

In this case, the scanning of the segment electrode X is performed by the pulse signal Vfx of the frequency “fx”, while the scanning of the common electrode Y is performed by the pulse signal Vfy of the frequency “fy”. The frequency “fx” of the pulse signal Vfx and the signal “fy” of the pulse signal Vfy correspond to the BPF (fx) 22 and the BPF
(fy) 23 is set to be separable.

Also, the frequency “fx” of the pulse signal Vfx and the signal “fy” of the pulse signal Vfy are set so as not to be an odd multiple of each other. This is because the pulse signal Vfx,
This is because if the waveform of Vfy is distorted, harmonics of odd multiples are included, so that the coordinate detection accuracy is not reduced by that.

In the case of this embodiment, since the scanning of the segment electrode X and the common electrode Y are performed simultaneously as described above,
An induced voltage in which an induced voltage based on the pulse signal Vfx and an induced voltage based on the pulse signal Vfy are superimposed on the tip electrode of the electronic pen 11. Then, the induced voltage signal from the electronic pen 11 is amplified by the operational amplifier 12 and then input to the BPF (fx) 22 and the BPF (fy) 23.

Then, the BPF (fx) 22 transmits only the component of the frequency “fx” of the input induced voltage signal to the x coordinate detection circuit 8. On the other hand, BPF
(fy) 23 is a frequency “fy” of the input induced voltage signal.
And passes it to the y-coordinate detection circuit 9.

As a result, only the induced voltage signal based on the segment electrode scanning signal x (the pulse signal Vfx is inserted during the scanning period) is input to the x coordinate detection circuit 8. on the other hand,
Only the induced voltage based on the common electrode scanning signal y (the pulse signal Vfy is inserted during the scanning period) is input to the y coordinate detection circuit 9.

Then, the x coordinate detection circuit 8 sets
Based on the input signal from the PF (fx) 22 and the timing signal from the control circuit 10, the x-coordinate of the position pointed by the tip of the electronic pen 11 is detected, and the x-coordinate signal representing the x-coordinate is output. The y-coordinate detection circuit 9 detects the y-coordinate of the position pointed to by the tip of the electronic pen 11 based on the input signal from the BPF (fy) 23 and the timing signal from the control circuit 10, and indicates the y-coordinate. Outputs coordinate signals.

FIG. 14 shows the segment electrode scanning signal x.
Alternatively, as the high-frequency voltage signal Vfx or the high-frequency voltage signal Vfy inserted during the scanning period of the common electrode scanning signal y,
5 is a timing chart of a coordinate detection period when the sine wave signal is used.

In this case as well, the segment electrodes X and the common electrodes Y are set in such a manner that the frequencies of the scanning periods of both scanning signals do not become odd multiples of each other.
And can be scanned simultaneously.

In FIGS. 13 and 14, the period of the pulse signal or the sine wave signal is considerably enlarged for easy understanding.

As described above, in this embodiment, the high-frequency voltage signal Vfx having the frequency “fx” is different from the segment electrode scanning signal x inserted during the scanning period and the frequency “fx”. The signal Vfy is applied to the segment electrode X by the common electrode scanning signal y inserted during the scanning period.
And the common electrode Y are simultaneously scanned. Then, only the component of the frequency “fx” of the induced voltage signal induced at the tip electrode of the electronic pen 11 is selectively x by the BPF (fx) 22.
Is sent to the coordinate detection circuit 8 and only the component of the frequency "fy" is
The signal is selectively sent to the y-coordinate detection circuit 9 by the PF (fy) 23.

Therefore, an induced voltage based on the corresponding scanning signal is simultaneously input to each of the x-coordinate detection circuit 8 and the y-coordinate detection circuit 9, and the electronic pen 1
The x coordinate and the y coordinate of one tip can be detected simultaneously.

That is, according to the present embodiment, the coordinate detection period is reduced to approximately 1/2 compared to the case where the x-coordinate detection period and the y-coordinate detection period are performed in different periods as in the above embodiments. And the display period in one frame period can be lengthened.

<Third Example> As described in detail in the first example, in order to prevent the liquid crystal filled in the liquid crystal panel 1 from being electrolyzed and shortening its life, the liquid crystal forming each pixel is prevented. The direction of the voltage applied to the layer
Invert according to the level of o.

FIG. 15 shows the common drive circuit 2 and the segment drive circuit 3 of the display-integrated tablet device shown in FIG.
3 is a diagram showing a specific example of the analog switch system in FIG. Analog switch system in the common drive circuit 2, the common electrodes Y _1, Y _2, ..., the transfer gate parallel pair G is connected to each of _{Y 8 1 / G 2, G} 3 / G 4, ..., G _Five
/ G ₆ , an inverter connected between the gate terminal of each transfer gate G ₁ , G ₃ ,..., G ₅ and the corresponding output terminal of the common selection circuit 31, and each transfer gate G ₁ , G ₃ ,. , a transfer gate parallel pair G ₃₁ / G ₃₂ connected to the input terminal of G _5, the transfer gates G _2, G _4, ..., the transfer gate parallel pair G ₃₃ / G ₃₄ connected to the input terminal of G ₆ And each transfer gate G
_31, the gate terminal and the switching circuit 7 of the G ₃₃ (see FIG. 1)
And an inverter connected between the AC signal output terminals FRO.

The analog switch system in the segment drive circuit 3 includes segment electrodes X ₁ , X ₂ ,.
Transfer gate parallel pairs G ₁₁ / G ₁₂ , G ₁₃ / G ₁₄ , G ₁₅ / G ₁₆ ,..., G ₁₇ / G ₁₈ connected to each of the ₄₀ transfer gates, and transfer gates G ₁₁ , G ₁₃ , G _15. , ..., an inverter connected between a corresponding output terminal of the gate terminal and the segment control circuit 32 of the G _17, the transfer gates G
_{11, G 13, G 15 ...} , and the transfer gate parallel pair G ₂₃ / G ₂₄ connected to the input terminal of G _17, the transfer gates _{G 12, G 14, G 16} ..., are connected to the input terminal of the G ₁₈ And a transfer gate parallel pair G ₂₁ / G _22, and an inverter connected between the gate terminals of the transfer gates G ₂₁ and G ₂₃ and the AC signal output terminal FRO of the switching circuit 7.

Each transfer gate is turned on when a signal of level "H" is input to its gate terminal.
On the other hand, when a signal of level “L” is inputted,
Becomes

When selecting the common electrode Y or the segment electrode X, the common selection circuit 31 and the segment control circuit 32 output a selection signal of level "H" from the corresponding output terminal, while the non-selection In this case, a selection signal of level "L" is output.

In the configuration of the common drive circuit 2 and the segment drive circuit 3, the following operation is performed during the y-coordinate detection period when the level of the alternating signal fro from the switching circuit 7 is "H", for example.

When the level "H" AC conversion signal fro is input to the common drive circuit 2, the transfer gate G ₃₂ ,
G ₃₄ is turned “on”, and each transfer gate G ₁ ,
The bias power supply V ₁ from the power supply circuit 5 is input to the input terminals of G ₃ ,..., G ₅ . On the other hand, each transfer gate G ₂ ,
G _4, ..., a bias power supply V ₅ is input to the input terminal of the G _6.

Here, for example, when the common electrode Y ₁ is selected, a selection signal of level “H” is output from the common selection circuit 31 to the gate terminal of the transfer gate pair G ₁ / G ₂ , results the bias power supply V ₅ is output from the transfer gate G ₂ with respect to the common electrode Y _1. On the other hand, the transfer gate pair G ₃ / G ₄ , ..., G ₅ /
It is output selection signal of level "L" to the gate terminal of the G _6, as a result the transfer gates G _3, ..., the common electrode Y ₂ from the G _5, ..., is the bias power source V ₁ with respect to Y ₈ Is output.

[0272] Similarly, when the alternating signal fro the level "H" to the segment drive circuit 3 is input transfer gate G _22, G ₂₄ is turned "on", the transfer gates G _12, G _14, G _16, ..., the power supply circuit 5 to the input terminal of the G ₁₈
, A bias power supply V ₀ is input. On the other hand, the transfer gates _{G 11, G 13, G 15} , ..., a bias power supply V ₂ is input to the input terminal of the G _17.

Since all the segment electrodes X are not selected during the y-coordinate detection period, the transfer gate pair G ₁₁ / G ₁₂ , G
₁₃ / G _14, ..., the selection signal is the output of level "L" to the gate terminal of the G ₁₇ / G _18, resulting transfer gates _{G 11, G 13, G 15} , ..., segment electrode from G ₁₇ X
_{1, X 2, X 3,} ..., the bias power supply V ₂ is output to the Y _40.

[0274] As a result, while the voltage │V ₅ -V ₂ │ is applied between the selected common electrode Y ₁ and the segment electrode X, the unselected common electrodes Y _2, ..., Y ₈ and the segment electrode X During this period, the voltage | V ₁ −V ₂ | is applied.

Thereafter, the common electrodes Y ₂ , Y ₃ ,..., Y ₈ are sequentially selected, and a voltage | V ₅ is applied between the selected common electrode Y and the segment electrode X as shown in FIG. 16 (FIG. 3). −V ₂ | is applied.

Next, the following operation is performed during the y-coordinate detection period when the level of the AC conversion signal fro is inverted.

[0277] When the AC signal fro the level "L" to the common drive circuit 2 and the segment drive circuit 3 is inputted, the transfer gates G _31, G ₃₃ and transfer gates G _21, G ₂₃ is "ON" . As a result, the voltage | V ₀ −V ₃ | is applied between the selective common electrode Y and the segment electrode X in exactly the same manner as described above.

In this way, the direction of the voltage applied to the liquid crystal is inverted according to the level inversion of the AC conversion signal fro.

The above-mentioned technique is an extremely effective and indispensable technique for a liquid crystal display. However, when one liquid crystal panel 1 is used for both the image display function and the tablet function, it is an extremely troublesome technique. Therefore, in order to avoid various problems, in the first example, a display integrated tablet device using a liquid crystal is realized by controlling the level inversion control of the alternating signal fro independently in the display period and the coordinate detection period. doing.

FIG. 17 is a diagram in which the display period in FIG. 16 is omitted and only the coordinate detection period is enlarged and displayed.

For example, as described in the second embodiment, if 400 common electrodes Y and 640 segment electrodes X are scanned as one block of 16 blocks, the number of electrode blocks of the common electrode Y is 25. Thus, the number of electrode blocks of the segment electrodes is 40.

Each common electrode block has the structure shown in FIG.
A common electrode scanning signal y having a scanning pulse having a pulse width "Ta" as shown in FIG. On the other hand, each segment electrode block has a segment electrode scan signal x having a scan pulse having a pulse width “Tb” as shown in FIG.
Enter

The position of each scanning pulse differs depending on each common electrode block and each segment electrode block.

FIG. 17C shows each common electrode Y shown in FIG.
While inputting a common electrode scanning signal y as shown in FIG. 7A and inputting a segment electrode scanning signal x as shown in FIG. 3 shows the voltage of the common electrode Y.

Here, in one coordinate detection period, all the common electrodes Y and the segment electrodes X are scanned once each time. Therefore, in FIG. 17, in the y coordinate detection period and the x coordinate detection period in the coordinate detection period 1,
A common electrode scanning signal y or a segment electrode scanning signal x as shown in FIG. 17A or FIG. 17B is input to all the common electrodes Y and all the segment electrodes X at different timings of the scanning pulse. Is done.

Therefore, the average voltages of the individual common electrodes Y and the segment electrodes X in the coordinate detection period 1 have the same value. As a result, the average value of the voltage value of the common electrode Y with respect to the segment electrode X in each pixel shown in FIG.

The average value of the voltage of the common electrode Y with respect to the segment electrode X in each pixel (hereinafter, simply referred to as the average voltage between electrodes) is given by the following equation (1).

[0288]

(Equation 1)

Now, each display condition is as follows: 1) Number of pixels = 400 × 640 2) Length of y coordinate detection period = 25 Ta (1 common electrode block: 16 lines, Number of common electrode blocks: 25) 3) X coordinate detection period length = 40TB (1 segment electrode block: 16, the number of segment electrodes block: 40), and further, 4) Ta = Tb 5) V 0 = 0.0V, V 1 = 1.7V, V 2 = 3.4
Assuming that V V ₃ = 23.5 V, V ₄ = 25.2 V, and V ₅ = 26.9 V, the average voltage Vdc between the electrodes in the coordinate detection period 1 in which the level of the AC conversion signal fro is “H” is Vdc = -1.26V.

The level of the AC conversion signal fro is "L".
The average voltage Vdc between the electrodes in the coordinate detection period 2 is Vdc = + 1.26V.

As described above, the level of the alternating signal fro is inverted for each frame (that is, for each coordinate detection period), so that not only the voltage direction applied to each pixel during the coordinate detection period is inverted, but also Polarity of average voltage applied to pixel
(The same absolute value) is also inverted.

As a result, by repeating the coordinate detection, the inter-electrode voltage average value Vdc for each pixel becomes substantially "0 V", whereby the electrolysis of the liquid crystal is prevented, and the deterioration of the liquid crystal due to the electrolysis is avoided.

However, as described above, the AC signal
When the voltage direction applied to the liquid crystal is inverted by the level inversion of fro, as shown in FIGS. 17A and 17B, the level of the non-scanning voltage in the common electrode scanning signal y and the segment electrode scanning signal x is increased. Is inverted for each coordinate detection period. As a result, as shown in FIG. 18, even when the tip position of the electronic pen 11 is the same in the coordinate detection period 1 and the coordinate detection period 2, the polarity of the induced voltage signal Vp output from the tip electrode of the electronic pen 11 is changed. Is inverted.

The inversion of the polarity of the induced voltage signal Vp from the electronic pen 11 causes the following problem.

[0295] First, as shown in FIG.
In the case where the operational amplifier 12 is built in, the bipolar power supply voltage is required in order to match the bipolar amplification characteristics of the operational amplifier 12.
Therefore, the number of lead wires for supplying a voltage to the electronic pen 11 increases.

Also, if the structure of the electronic pen 11 is simplified, the x-coordinate detection circuit 8 and the y-coordinate
Even if an operational amplifier is installed in the system, power supplies with different polarities are still required.

Even if a bipolar power supply is prepared and the bipolar is amplified, the coordinates of the tip of the electronic pen 11 must be calculated based on the output voltages having different polarities. The y-coordinate detection circuit 9 becomes complicated.

Further, as described in the first embodiment, even if the induced voltage signal from the electronic pen 11 is subjected to full-wave rectification before the amplification and the polarities are made uniform, the voltage of the induced voltage signal is only 30 mV. This operation is difficult due to the characteristics of the diode.

Further, due to the characteristics of the operational amplifier 12 and the like, the x- and y-coordinates of the tip position of the electronic pen 11 according to the level inversion of the AC signal fro despite the same position of the electronic pen 11. May be different.

Therefore, in the third example, the various problems described above are solved by preventing the polarity of the induced voltage signal from the electronic pen 11 from being inverted. That is, the display-integrated tablet device in the third example is a display-integrated tablet device for achieving the third object.

Ninth Embodiment As described above, in order to prevent the polarity of the induced voltage signal from the electronic pen 11 from being inverted, the level of the AC signal fro should be inverted for each coordinate detection period. It is necessary to prevent liquid crystal electrolysis.
For this purpose, the inter-electrode voltage average value Vdc during all coordinate detection periods may be set to “0 V”.

Therefore, in this embodiment, the inter-electrode voltage average value Vdc during the coordinate detection period is set to "0 V" without providing another power supply circuit.

FIG. 19 is a block diagram of an analog switch system of the common drive circuit 2 and the segment drive circuit 3 in the display-integrated tablet device of this embodiment. FIG.
Prior to describing the display-integrated tablet device of the present embodiment according to No. 9, the common electrode scanning signal y and the segment electrode scanning signal x input to the common electrode Y and the segment electrode X during the coordinate detection period in the present embodiment will be described. I do.

The inter-electrode voltage average value Vdc during the coordinate detection period is given by equation (1) as described above.

Here, also in this embodiment, each of the 400 common electrodes Y and the 640 segment electrodes X is 1
It is assumed that scanning is performed in units of blocks as 16 blocks. At this time, a common electrode scanning signal y whose non-scanning voltage is “Vc1”, the pulse width of the scanning pulse is “Ta”, and the voltage is “Vc2” is input to the common electrode Y. On the other hand, a segment electrode scanning signal x whose non-scanning voltage is “Vs1”, the pulse width of the scanning pulse is “Tb”, and the voltage is “Vs1” is input to the segment electrode X.

Then, the average voltage Vdc between the electrodes is obtained from the equation (1) as follows.

Vdc = [24Ta (Vc1-Vs1) + Ta (Vc2-Vs1) + 39Tb (Vc1-Vs1) + Tb (Vc1-Vs2)] / (25Ta + 40Tb) (2) Therefore, Ta, Tb, By appropriately combining the values of Vc1, Vs1, Vc2 and Vs2, the inter-electrode voltage average value Vdc can be set to "0".

The voltage constraint at this time is that the voltage between both electrodes during the coordinate detection period must be | V ₅ -V in order to prevent the voltage between both electrodes from exceeding the liquid crystal display voltage during the coordinate detection period. ₂ | and | V ₃ −V ₀ |. However, the values of the bias voltages V ₀ , V ₂ , V ₃ and V ₅ are the same as in the first embodiment.

In the above equation (2), the average value V
The largest factor for increasing the absolute value of dc is the value of the difference (Vc1−Vs1) between the non-scan voltage Vc1 of the common electrode scan signal y and the non-scan voltage Vs1 of the segment electrode scan signal x. This can be nod from the fact that the coefficient of the term (Vc1−Vs1) in the equation (2) is large.

Therefore, the most basic and effective method for reducing the inter-electrode voltage average value Vdc is to use the non-scan voltage Vc1 (that is, the reference voltage) of the common electrode scan signal y and the non-scan voltage of the segment electrode scan signal x. Voltage Vs1 (ie,
(Reference voltage).

For example, if Ta = Tb in the above equation (2), equation (3) is obtained.

Vdc = [64 (Vc1-Vs1) + (Vc2-Vs2)] / 65 (3) Further, if Vc1 = Vs1, equation (4) is obtained.

Vdc = (Vc2−Vs2) / 65 (4) Here, for example, while the voltage of the scan pulse of the common scan signal y (that is, the scan voltage) Vc2 is set to “23.5V”, the segment scan is performed. The scanning voltage Vs2 of the signal x is set to “1”.
Then, the average value Vdc between the electrodes becomes Vdc = 12/65 = 0.18 from Expression (4), which is a value within a negligible range.

However, when Vc1 ≠ Vs1, for example,
(Vc1−Vs1) = 2.0, Vc2 = 23.5V, Vs2 = 11.
Assuming that the voltage is 5 V, the value of the average voltage Vdc between the electrodes is “1.99”.
This is a value that cannot be ignored.

FIG. 20 shows a state in which the bias power supply from the power supply circuit 5 in the display-integrated tablet device of the first embodiment is used as it is, and Ta = Tb, Vc1 = Vs1 = V ₂ (= 3.4 V),
By a _{Vc2 = Vs2 = V 5 (=} 26.9V), the common electrode scanning signal y in the case where the "0" the value of the average voltage Vdc, between the segment electrode scanning signal x and the both electrodes 4 shows a voltage waveform.

According to FIG. 20, the peak value of the scanning pulse in the common electrode scanning signal y and the segment electrode scanning signal x is (V ₅ −V ₂ ). Here, it is advantageous that the higher the peak value of the scanning pulse, the higher the induced voltage from the electronic pen 11 can be obtained. However, when the scan pulse height value to a maximum value capable of utilizing the bias supply (V ₅ -V ₀₎ It is beyond the liquid crystal display voltage is falling back to the poor screen contrast.

As described above, the above-mentioned method can set the value of the inter-electrode voltage average value Vdc to "0" and obtain a high induced voltage without requiring the special power supply for the coordinate detection. So it is the easiest and surest way.

Therefore, in the analog switch system in the display-integrated tablet device shown in FIG. 19, the analog switch of the common drive circuit 2 and the segment drive circuit 3 in the display-integrated tablet device shown in FIG. The system (see FIG. 15) is devised as follows.

That is, the analog switch system in the display-integrated tablet device of the present embodiment is obtained by adding the power control circuit 33 to the configuration of the analog switch system in the display-integrated tablet device shown in FIG. Note that FIG.
15, the same components as those in FIG. 15 are denoted by the same reference numerals as in FIG. 15, and description thereof will be omitted.

The power supply control circuit 33 includes a transfer gate parallel pair G ₄₁ / G ₄₂ connected to the input terminal of the transfer gate G ₃₂ of the common drive circuit 2 and a transfer gate connected to the input terminal of the transfer gate G _34. The parallel pair G ₄₃ / G ₄₄ , the transfer gate parallel pair G ₄₅ / G ₄₆ connected to the input terminal of the transfer gate G ₂₂ of the segment drive circuit 3, and the transfer gate parallel connected to the input terminal of the transfer gate G _{24 G47} / _G48 and inverter 3 of common drive circuit 2
4 or an OR gate 36 connected to the inverter 35 of the segment drive circuit 3, one input terminal of the OR gate 36, and transfer gates G ₄₁ , G ₄₃ , G ₄₅ , G
It is roughly composed of an inverter 37 interposed between the gate terminal _{47 and} the gate terminal ₄₇ .

The mode control signal D is input to the input terminal of the OR gate 36 of the power supply control circuit 33 to which the inverter 37 is connected, and the AC signal fro is input to the other input terminal. Further, the input terminal of the transfer gate G _42, G ₄₈ enter the bias power supply V _2, the input terminal of the transfer gate G _44, G ₄₆ inputs the bias power supply V _5.

In this case, the transfer gates G ₄₄ and G ₄₈ are substantially unnecessary.

The mode control signal D is, for example, the control circuit 1
The signal is output from 0, and is a signal whose level is "H" during the coordinate detection period and whose level is "L" during the display period. As a result, the OR gate 36 outputs the AC signal during the display period.
While fro is output as it is, a signal of level "H" is always output during the coordinate detection period.

In the common drive circuit 2, the segment drive circuit 3, and the power supply control circuit 33 having the above configuration, the transfer gate parallel pair G ₄₁ / G ₄₂ selects the bias power supply V ₁ by the transfer gate G ₄₁ during the display period. On the other hand, during the coordinate detection period, the transfer gate G
_The bias power supply V ₂ is selected by ₄₂ and sent to the transfer gate G ₃₂ of the common drive circuit 2.

Similarly, the transfer gate parallel pair G ₄₃ / G ₄₄ selects the bias power supply V ₅ in any of the display period and the coordinate detection period to select the common drive circuit 2.
And it sends the to the transfer gate G _34. In the transfer gate parallel pair G ₄₅ / G ₄₆ , G ₄₇ / G ₄₈ , respectively, the bias power sources V ₀ , V ₂ are selected during the display period, while the bias power sources V ₅ , V ₂ are selected during the coordinate detection period. Then, the data is transmitted to the transfer gates G ₂₂ and G ₂₄ of the segment drive circuit 3.

As a result, during the display period, the common drive circuit 2 operates in the same manner as described with reference to FIG. 15, and uses the bias power supplies V ₀ , V ₁ , V ₄ , and V ₅ as shown in FIG. The common electrode drive signals a to h are generated. On the other hand, the segment drive circuit 3 operates in the same manner as described with reference to FIG. 15, and generates the segment electrode drive signals A and B as shown in FIG. 32 using the bias power supplies V ₀ , V ₂ , V ₃ and V ₅ . It is.

Since the output from the OR gate 36 is only "H" during the coordinate detection period as described above, the common drive circuit 2 sets the transfer gates G ₃₁ , G
₃₃ is closed and only the bias power supplies V ₂ and V ₅ are used.
A common electrode scanning signal y as shown in FIG.
On the other hand, the segment driving circuit 3
To close the _21, G _23, is to generate the segment electrode scanning signal x as shown in FIG. 20 (b) using only bias power V _2, V _5.

As a result, during the coordinate detection period,
The common electrode scanning signal y and the segment electrode scanning signal x having the scanning pulse whose reference voltage is the same “V ₂ ” and the peak value is the same “(V ₅ −V ₂ )” are generated.

FIG. 20C shows the common electrode Y shown in FIG.
The voltage between the two electrodes when the common electrode scanning signal y as shown in (a) is input and the segment electrode scanning signal x as shown in FIG.

In this case, since the voltage waveform between the two electrodes is symmetrical with the reference voltage “0 V” as a boundary, the average voltage Vdc between the electrodes is “0 V”, so that the electrolysis of the liquid crystal is prevented, Degradation of the liquid crystal due to decomposition is avoided.

As can be seen from FIGS. 20 (a) and 20 (b), during the coordinate detection period in this embodiment,
Common electrode scanning signal y and segment electrode scanning signal x
Does not invert the relationship between the scanning voltage level and the reference voltage level. Therefore, as shown in FIG. 21, the polarity of the induced voltage signal Vp from the electronic pen 11 is not inverted in the coordinate detection period 1 and the coordinate detection period 2.

As described above, in the display-integrated tablet device according to the present embodiment, the polarity of the induced voltage signal Vp from the electronic pen 11 is changed by providing the power supply control circuit 33 in the display-integrated tablet device shown in FIG. It can be prevented from being inverted. Therefore, the above-described induced voltage signal V
All of the problems associated with the polarity reversal of p can be solved.

In the above embodiment, the power supply control circuit 33 is formed separately from the common drive circuit 2 and the segment drive circuit 3, but may be formed on the same chip.

The power supply control circuit 33 may be configured as a part of the power supply circuit 5. In that case, the common drive circuit 2, the segment drive circuit 3, and the power supply circuit 5
And the circuit configuration of the display-integrated tablet device shown in FIG. 1 can be used as it is.

The configuration of the analog switch system in this embodiment is not limited to the configuration shown in FIG.

[Embodiment 10] This embodiment is similar to the eighth embodiment, except that the power supply control circuit 3 has a complicated circuit configuration.
3 (see FIG. 19) and other power supply circuits, without using the bias power supply from the power supply circuit 5 in the display-integrated tablet device of the first embodiment as it is.
= Tb, Vc1 = Vs1 = V 2 (= 3.4V), Vc2 = Vs2 = V 5
(= 26.9 V) in another embodiment.

FIG. 22 and FIG. 23 are block diagrams of the display-integrated tablet device of this embodiment. The display control circuit 4, power supply circuit 5, detection control circuit 6, and switching circuit 7 are shown separately in FIG. I have. The configuration of the display-integrated tablet device is significantly different from the configuration of the display-integrated tablet device shown in FIG. 1 in the following two points.

That is, first, the AC signal fro for inverting the direction of the voltage applied to the liquid crystal of the liquid crystal panel 1 is generated by the FR signal generation circuit 41.

Second, a switch 42 for switching and selecting a bias power supply input to the common drive circuit 2 is provided.

Since the other configurations are substantially the same,
The same reference numerals as in FIG. 1 denote the same parts, and a detailed description thereof will be omitted.

The FR signal generation circuit 41 is
The switching is controlled by a mode switching signal mode from. In the display period, which is the first mode, an AC signal fro whose frequency is inverted by level “H” or “L” is generated by frequency division by the clock signal cp1o from the switching circuit 7. On the other hand, during the coordinate detection period which is the second mode, the level of the AC conversion signal fro is fixed to, for example, “H”.

By stopping the level inversion of the alternating signal fro during the coordinate detection period, the polarity inversion of the voltage induced at the tip electrode of the electronic pen 11 is prevented. The AC signal fro during the coordinate detection period
Can be fixed at "L".

The switching of the switch 42 is controlled by a mode switching signal mode from the control circuit 10. Then, during the display period in the first mode, the bias power supply V ₁ from the power supply circuit 5 is input to the input terminal V ₁ of the common drive circuit 2 as in the case of the display-integrated tablet device of FIG. On the other hand, in the coordinate detection period is the second mode, the bias power supply V ₂ instead of the bias power supply V ₁
To the input terminal V1 of the common drive circuit 2.

Thus, the reference voltage of the common electrode scanning signal y during the coordinate detection period is changed to the same voltage “V ₂ ” as the reference voltage of the segment electrode scanning signal x.

As described above, the rest of the configuration is substantially the same as that of the display-integrated tablet device shown in FIG. 1, but since the AC signal fro is generated by the FR signal generation circuit 41, the common signal is used. The operation of the drive circuit 2, the segment drive circuit 3, the detection control circuit 6, and the switching circuit 7 at the time of coordinate detection is slightly different from the case of FIG.

That is, the detection control circuit 6 does not output the AC conversion signal frd as a matter of course because the generation of the AC conversion signal fro is no longer necessary. Also, it does not output the data signals D ₀ d to D ₃ d. Instead, the shift data for making the operation of the segment drive circuit 3 during the coordinate detection period the same serial operation as that of the common drive circuit 2
Output sxd.

[0347] In response to this, the switching circuit 7 outputs the shift data sxo in place of the AC conversion signal fro.

The segment drive circuit 3 is provided with a shift data input terminal DIO1X and a mode switching signal input terminal MODE. The shift data s from the switching circuit 7 is input to the shift data input terminal DIO1X.
xo is input, and the mode switching signal mode from the control circuit 10 is input to the mode switching signal input terminal MODE.

The display-integrated tablet device having the above configuration operates as follows to detect coordinates.

First, the FR signal generating circuit 41 and the switch 42 according to the mode switching signal mode from the control circuit 10.
And the segment drive circuit 3 is switched to the second mode. Then, the FR signal generation circuit 41 fixes the level of the AC conversion signal fro to “H”. Switch 4
2 selects the bias power supply “V ₂ ” side from the power supply circuit 5.

After that, the common drive circuit 2 operates as described with reference to FIG. 15 to sequentially select the common electrodes Y and input the common electrode scanning signal y. In this case, the bias power that is input to the transfer gates G ₃₂ as described above is "V _2", the level of the alternating signal fro the "H"
It is. Therefore, the scanning voltage of the common electrode scanning signal y input to the common electrode Y is “V ₅ ”, and the reference voltage is “V ₂ ”.

On the other hand, by switching to the second mode, the segment drive circuit 3 switches to a serial output operation based on shift data sxo similar to the operation of the common drive circuit 2.

That is, the clock signal cp1o output from the output terminal CP10 of the switching circuit 7 is applied to the input terminal L
When input to P, the pulse of the shift data sxo output from the output terminal SXO of the switching circuit 7 is taken into the shift register (not shown) from the input terminal DIO1X in synchronization with the input clock signal cp1o. . And
Scan pulses of the corresponding segment electrode scanning signals x _{1 to} x ₄₀ are sequentially output from output terminals 01 to 040 corresponding to the pulse positions of the shift data sxo shifted in synchronization with the clock signal cp1o by the shift register.

At this time, the segment electrode scanning signal x
Voltage (scan voltage) of the scanning pulse is generated based on the bias power supply V _5, the reference voltage is generated based on the bias power supply V _2.

The voltage applied to the switch 42 is at most a bias power supply V ₂ (= 3.4 V) and the current is small, so that an element having a very low withstand voltage may be used, as in the transfer gates G ₄₁ and G ₄₂ in FIG. What is necessary is just to comprise. The switch 42 is connected to the common drive circuit 2 or the power supply circuit 5.
May be formed on the same chip.

Although various modifications of the ninth embodiment can be considered, representative ones will be described below.

[Embodiment 10-1] In this embodiment,
The output driver of the common drive circuit 2 and the segment drive circuit 3 is not an analog switch system composed of transfer gates as shown in FIG. 15, but an analog switch system composed of transistor groups as shown in FIG.

At that time, the output driver on the common drive circuit 2 side can output five types of voltages including the bias power supply V ₂ .

[Embodiment 10-2] In this embodiment,
The configuration of the power supply circuit 5 for supplying bias power to the common drive circuit 2 and the segment drive circuit 3 is as shown in FIG.

[0360] That is, the provision of the switch 43 (corresponding to the switch 42) to the output system of the bias power supply V _1. Then, by switching the switch 43 in the mode signal mode from the control circuit 10, the second mode (when the coordinate detection) is to be output to the bias power supply V ₂ from an output terminal of the bias power supply V ₁ .

In this case, since the segment drive circuit 3 generates the segment electrode scanning signal x using the bias power supplies V ₀ , V ₂ , V ₃ and V ₅ , the voltage from the output terminal of the bias power supply V ₁ Even if it changes, the operation of the segment drive circuit 3 is not affected at all.

[Eleventh Embodiment] In the eighth embodiment and the ninth embodiment, in order to set the average voltage Vdc between electrodes to “0”, Ta = Tb, Vc1 = Vs1 = V ₂ ( = 3.
4V), is set to _{Vc2 = Vs2 = V 5 (=} 26.9V). However, depending on various other conditions, it is necessary to generate the common electrode scanning signal y and the segment electrode scanning signal x by a combination of bias power supplies different from the above.

For example, the electronic pen 11 is connected to the liquid crystal panel 1
When placed on the upper side, the peak value of the voltage induced on the tip electrode of the electronic pen 11 during scanning of the electrode on the contact surface side (that is, the upper side of the segment electrode X in each of the above-described embodiments) is different from that of the electrode on the opposite side (the above-described electrode). In each embodiment, the voltage exhibits a value significantly higher than the peak value of the voltage induced during scanning of the common electrode Y). Therefore, separate amplifiers and comparators for scanning the common electrodes and scanning the segment electrodes are required.

To avoid such a problem, the fifth
In the embodiment, the peak value V of the scanning pulse applied to the lower electrode (the common electrode Y in the fifth embodiment).
Make d higher.

In such a case, however, in the eighth embodiment, the symmetry at the boundary of the reference voltage “0 V” of the bipolar electrode voltage waveform as shown in FIG. The value Vdc deviates from "0".

[0366] Therefore, in this embodiment, detailed description will be avoided but, Vc1 ≠ V from a bias power supply V ₀ ~V ₅ of the value of the non-scan voltage Vc1, Vs1 from the power supply circuit 5
s1 and the inter-electrode voltage average value Vdc is appropriately selected to be "0".

At this time, if there is no voltage satisfying the condition among the bias power supplies V _{0 to} V ₅ , an appropriate voltage is prepared separately from the power supply circuit 5. Then, the non-scan voltage Vc1, Vs1 is set is input to the transfer gates G _42, G ₄₈ in the power supply control circuit 33, scanning voltage Vc2, Vs2 is to input to the transfer gates G _44, G _46.

By doing so, the peak value of the voltage induced at the tip electrode of the electronic pen 11 during the common electrode scanning and the segment electrode scanning is made the same, and the inter-electrode voltage average value Vdc is set to “0”. You can do it.

[Twelfth Embodiment] In this embodiment, the common voltage Vdc between electrodes is set to "0" while increasing the peak value Vd of the scanning pulse applied to the lower electrode. The pulse width Ta of the scanning pulse of the electrode scanning signal y
And pulse width T of scanning pulse of segment electrode scanning signal x
Change b.

In the above equation (2), Vc1 = Vs1, Vdc =
Assuming 0, equation (5) is obtained.

Ta = Tb (Vs2−Vc1) / (Vc2−Vs1) (5) Here, assuming that Vc1 = Vs1 = 0V, Expression (5) becomes Ta = Tb · Vs2 / Vc2 (6) .

Therefore, as shown in FIG. 26, the peak value "Vs2" of the scanning pulse of the segment electrode scanning signal x with respect to the segment electrode X on the upper side is equal to the peak value "Vs2" of the common electrode Y with respect to the common electrode Y on the lower side. If the peak value “Vc2” of the scanning pulse is 1 / K, the segment electrode scanning signal x
The pulse width “Tb” of the scanning pulse of the common electrode scanning signal y
By making the pulse width “Ta” of the scanning pulse “K” times as high as above, the inter-electrode voltage average value Vdc can be made “0”.

In the above embodiment, Vc1 = Vs1 = 0
The above effect can be obtained if the relationship of Vc1 = Vs1 is simply satisfied.

[Thirteenth Embodiment] In this embodiment, the common voltage Vdc between electrodes is set to "0" while increasing the peak value Vd of the scanning pulse applied to the lower electrode. The peak value (Vc3−Vc) is set at a position that does not contribute to coordinate detection at the end of the coordinate detection period in either the electrode scanning signal y or the segment electrode scanning signal x.
1) A pulse having a pulse width Tf is inserted.

Thus, the common electrode scanning signal y when the inter-electrode voltage average value Vdc during scanning of both electrodes Y and X is negative instead of “0”, and the segment electrode scanning signal y when positive. By inserting the pulse into x, the inter-electrode voltage average value Vdc is corrected to "0".

FIG. 27 shows an example in which the pulse is inserted into the common electrode scanning signal y.

In FIG. 27, the pulse is inserted at the end of the coordinate detection period, but may be anywhere as long as it does not contribute to coordinate detection during the coordinate detection period.
It may be inserted at the front end of the coordinate detection period or at the boundary between the y coordinate detection period _TD1y and the x coordinate detection period _TD1x .

At this time, since the pulse is inserted at a position that does not contribute to coordinate detection, its pulse width Tf and peak value
By setting (Vc3-Vc1) freely, the inter-electrode voltage average value Vdc can be correctly set to "0".

[Fourteenth Embodiment] The fourteenth embodiment is similar to the third embodiment.
This is an example in which the third example is applied when inserting the high-frequency voltage signals Vfy and Vfx during the scanning period of the electrode scanning signal in the embodiment or the seventh embodiment.

FIG. 28 shows the high-frequency voltage signals Vfy and Vfx.
An example in which the above sine wave signal is used is shown. FIG.
As shown in FIGS. 28A and 28B, the period of the sine wave signal inserted in the scanning period is the scanning period “Ta” in the common electrode scanning signal y and the scanning period “Tb” in the segment electrode scanning signal x. It is shorter. Further, the reference voltage in the common electrode scanning signal y and the segment electrode scanning signal x is set to the same voltage “V ₈ ”.

As a result, as shown in FIG. 28 (c), the value of the DC component of the voltage between both electrodes becomes “0”,
The average voltage Vdc between the electrodes can be substantially set to “0”.

As an actual configuration in this embodiment, the power supply control circuit 33 (see FIG. 19) and the high-frequency power supply circuit 21 (see FIG.
Reference). And the high frequency power supply circuit 2
While a sine wave input signal Vfy output from 1 to the transfer gates G ₄₄ of the power supply control circuit 33, the sine wave signal V
the fx is input to the transfer gate G _46. Further, a DC voltage signal of the same voltage “V ₈ ” is input to the transfer gates G ₄₂ and G ₄₈ of the power supply control circuit 33. Thus, through the transfer gate G ₄₁ ~G ₄₈ to open and close by the mode control signal D is controlled, sinusoidal signal Vfy the coordinate detection period, since the application of Vfx and DC voltage signal to the common electrode Y or the segment electrode X is there.

The reference voltage is preferably a DC voltage, but is not particularly limited to a DC voltage. It is only necessary that the reference voltages of the common electrode scanning signal y and the segment electrode scanning signal x be substantially equal.

In the above embodiment, sine wave signals are used as the high-frequency voltage signals Vfy and Vfx inserted during the scanning period of the electrode scanning signals x and y, but rectangular wave signals may be used. In this case, there is no need to provide a special high-frequency power supply as in the case of a sine wave signal, and this can be realized only by adding a gate circuit to the analog switch system.

As described above, in this embodiment, since the high-frequency voltage signals Vfy and Vfx are inserted during the scanning period of the electrode scanning signals x and y, there is no reversal of the application direction of the DC voltage applied to the liquid crystal. . Therefore, by passing the voltage induced at the tip electrode of the electronic pen 11 through a filter that can pass only the components of the frequencies “fy” and “fx”, an induced voltage signal Vp without polarity inversion as shown in FIG. 29 is obtained. be able to. Note that FIG. 29 shows the induced voltage signal Vp when a rectangular wave signal is used as the high frequency voltage signals Vfy and Vfx.

By rectifying the induced voltage signal Vp thus obtained, it is converted into a signal as shown in FIG. 21 and the tip coordinates of the electronic pen 11 are obtained.

When the high-frequency voltage signals Vfy and Vfx are inserted during the scanning period of the electrode scanning signal as in the present embodiment, as described in the third embodiment, the common electrode Y and the segment electrode X are Since the impedance with respect to the pen 11 is reduced, a large induced voltage is obtained. Also,
Since only the frequency component of the high-frequency voltage signal inserted during the scanning period of the electrode scanning signal can be detected, it is possible to obtain effects such as removal of noise caused by friction of the electronic pen 11 and external noise components.

In the diagram used in the description of the third example, the coordinate detection period is set immediately after the display period in order to make the contents easy to understand. However, actually, a preparation period is inserted between the display period and the coordinate detection period according to the control timing in the control circuit 10. If this preparation period is short, this period may be ignored, but if it is long, the voltage of this preparation period must be taken into account when obtaining the inter-electrode voltage average value Vdc.

[0389]

According to the present invention, not only a compact and low-cost display-integrated tablet device can be obtained, but also coordinate detection can be performed with high accuracy and stability at the time of coordinate detection, resulting in highly reliable display. An integrated tablet device can be provided.

According to the present invention, a good display image with little disturbance can be obtained.

Also, since the coordinates are displayed for the detected coordinates, it is possible to input stably with the pointing means such as an electronic pen as if writing characters or figures on paper.

[Brief description of the 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.

FIG. 2 is a timing chart of a display period and a coordinate detection period.

FIG. 3 is a diagram illustrating an example of a segment electrode scanning signal output during an x coordinate detection period and a common electrode scanning signal output during a y coordinate detection period in FIG. 2;

FIG. 4 is a diagram illustrating an example of a waveform of an alternating signal.

FIG. 5 is an explanatory diagram of a waveform change of a scanning signal at a point of time when a level of an alternating signal is inverted.

FIG. 6 is an explanatory diagram of a level inversion cycle of an AC signal.

FIG. 7 is an explanatory diagram of a segment electrode scanning signal and a common electrode scanning signal when scanning a plurality of electrodes at a time.

FIG. 8 is an explanatory diagram of a common electrode scanning signal when the same effect as when a plurality of electrodes are scanned at once is obtained by performing electrode scanning one by one.

FIG. 9 is an explanatory diagram of a segment electrode scanning signal and a common electrode scanning signal in which a high-frequency rectangular wave is inserted during a scanning period.

FIG. 10 is an explanatory diagram of a segment electrode scanning signal in which a high-frequency sine wave is inserted during a scanning period.

FIG. 11 is a diagram illustrating an example of a common electrode drive signal when performing electrode scanning during a display period.

FIG. 12 is a block diagram of one embodiment of a display-integrated tablet device according to a second embodiment of the present invention.

FIG. 13 is a timing chart of a segment electrode scanning signal and a common electrode scanning signal when x-coordinate detection and y-coordinate detection are performed simultaneously.

FIG. 14 is a timing chart of a segment electrode scanning signal and a common electrode scanning signal different from FIG. 13 when the x coordinate detection and the y coordinate detection are performed simultaneously.

15 is a diagram showing a specific example of an analog switch system of a common drive circuit and a segment drive circuit in the display-integrated tablet device shown in FIG.

16 is a timing chart of driving signals and scanning signals generated by the display-integrated tablet device having the analog switch system shown in FIG.

FIG. 17 is a diagram in which a display period in FIG. 16 is omitted.

18 is an explanatory diagram of an induced voltage signal output from the electronic pen based on the common electrode scanning signal and the segment electrode scanning signal shown in FIG.

FIG. 19 is a diagram showing an example of an analog switch system of a common drive circuit and a segment drive circuit in a display-integrated tablet device according to a third embodiment of the present invention.

20 is an explanatory diagram of a common electrode scanning signal, a segment electrode scanning signal, and a voltage between both electrodes generated by the display-integrated tablet device shown in FIG. 19;

21 is an explanatory diagram of an induced voltage signal output from the electronic pen based on the common electrode scanning signal and the segment electrode scanning signal shown in FIG.

FIG. 22 is a block diagram of a display-integrated tablet device different from FIG. 19 in the display-integrated tablet device according to the third example.

FIG. 23 is a block diagram of the display-integrated tablet device following FIG. 22.

24 is a configuration diagram of an analog switch system of a common drive circuit and a segment drive circuit in an embodiment different from FIGS. 22 and 23. FIG.

FIG. 25 is a configuration diagram of a power supply circuit in an embodiment different from FIGS. 22, 23 and 24;

FIG. 26 is an explanatory diagram of a common electrode scanning signal, a segment electrode scanning signal, and a voltage between both electrodes that sets the average value Vdc between electrodes to “0” by manipulating a peak value and a pulse width of a scanning pulse.

FIG. 27 is an explanatory diagram of a common electrode scanning signal, a segment electrode scanning signal, and a voltage between both electrodes, in which a pulse is inserted into a section of the scanning signal that does not contribute to coordinate detection to set the average voltage Vdc between electrodes to “0”. .

FIG. 28 is a common electrode scanning signal in which a high-frequency voltage signal is inserted during a scanning period and an inter-electrode voltage average value Vdc is set to “0”;
FIG. 4 is an explanatory diagram of a segment electrode scanning signal and a voltage between both electrodes.

29 is an explanatory diagram of an induced voltage signal output from the electronic pen based on the common electrode scanning signal and the segment electrode scanning signal shown in FIG.

FIG. 30 is a block diagram of a duty type liquid crystal display device.

FIG. 31 is a detailed view of a terminal of the common drive circuit shown in FIG. 30;

32 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.

FIG. 33 is an explanatory diagram of a display image based on the common electrode drive signal and the segment electrode drive signal shown in FIG. 32.

34 is an explanatory diagram of a level inversion cycle of an alternating signal in the duty type liquid crystal display device shown in FIG. 30.

FIG. 35 is a block diagram of an electrostatic induction tablet and its driving unit.

36 is a diagram illustrating an example of a column electrode scanning signal and a row electrode scanning signal generated by the driving unit illustrated in FIG. 35.

FIG. 37 is an explanatory diagram of a signal waveform output from the electronic pen in FIG. 35;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... 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 ... x coordinate detection circuit, 9 ... y coordinate detection circuit,
10: control circuit, 11: electronic pen,
12 ... operational amplifier, 21 ... high frequency power supply circuit, 22, 23 ... BPF, 33 ...
Power supply control circuit, 41 ... FR signal generation circuit, 42, 43 ... Switch.

Claims (18)

(57) [Claims] A first electrode and a second electrode, each of which is arranged along a direction different from each other;
A display panel having a pixel corresponding to a location where the electrode and the second electrode intersect; an indication unit capacitively coupled to the first electrode and the second electrode to indicate a position on the surface of the display panel; and driving the first electrode A first electrode driving unit that drives a second electrode; a second electrode driving unit that drives a second electrode; and a voltage corresponding to each pixel by controlling the first electrode driving unit and the second electrode driving unit. A display control means for setting a display period for displaying a desired image by applying to the electrodes; and a first electrode driving means and a second electrode driving means for controlling
A scanning period in which a scanning voltage is sequentially applied to the electrode or the second electrode
And the detection control means for measuring the time from the start of scanning, and the direction of application of the voltage applied to each pixel during the display period.
Setting control means for switching and setting at predetermined intervals, and a second setting control means for setting a scanning voltage application direction in a scanning period.
Control means , based on the induced voltage induced by the indication means due to capacitive coupling of the scanning voltage applied by the indication means and the detection control means and the time measured by the detection control means, When switching between coordinate detection means for performing coordinate detection, and first setting control means and second setting control means,
In both cases, the display control means and the
A display integrated tablet device comprising: a switching control means for switching between the detection control means and the detection control means . 2. The display-integrated tablet device according to claim 1, wherein said display panel is a liquid crystal display panel. 3. The first electrode driving means is controlled during the scanning period.
Scanning period in which scanning voltage is sequentially applied to the first electrodes by controlling
After the first scanning period, the second electrode driving means is controlled to
A second scanning period in which a scanning voltage is sequentially applied to the two electrodes;
The display-integrated tablet device according to claim 1 or 2, wherein an idle time is provided between the first scanning period and the second scanning period . 4. The display-integrated tablet device according to claim 3, wherein the second setting control means performs setting control to invert the scanning voltage application direction during the idle time. 5. The method according to claim 1, wherein each pixel is controlled by a first setting control means.
The switching timing of the voltage application direction is determined by the second setting control procedure.
It is not the same as the setting timing of the scanning voltage application direction by the stage.
The switching timing by the first setting control means.
Duty ratio is 1 and the first setting system in the display period.
Last time in voltage application direction by control means and next display period
Of the voltage application direction by the first setting control means in
2. The method according to claim 1, wherein time and time are complementary.
A display integrated tablet device according to claim 2. 6. The coordinates detected by said coordinate detecting means.
Is displayed by the display control means.
Claim 1, Claim 2, Claim 3, Claim 4, or
A display integrated tablet device according to claim 5. 7. The coordinates detected by said coordinate detecting means.
The information is transferred to the display control means during the subsequent display period.
In the subsequent display period, the table
7. The display according to claim 6, wherein the information is displayed on a display panel.
Display integrated tablet device. 8. The method according to claim 1 , wherein each scanning voltage is applied during a scanning period.
Pressure and direction of application are constant and average DC of each pixel
2. The method according to claim 1, wherein the voltage value is set to zero.
The display-integrated tablet device according to claim 2. 9. A first electrode driving means and a second electrode driving means.
Voltage supply means for supplying at least four types of voltages to
In the display period, the method of applying the voltage from the first setting control
One of at least four voltages depending on the direction
Display by applying the voltage corresponding to each pixel based on the pressure
In the scanning period, the voltage application method from the second setting control means is used.
One of at least four voltages depending on the direction
Each scanning voltage is applied based on pressure
The display-integrated tablet according to claim 1 or 2.
apparatus. 10. A first electrode driving means and a second electrode driving means.
Stage _{V 5> V 4> V 3} > V 2> V 1> V 0 becomes six relationships
Voltage supply means for supplying a voltage, and a voltage corresponding to each pixel is set to (V ₅ −
V ₀ ), and the voltage between the first electrode and the second electrode during the scanning period is (V ₀ ).
₃ -V ₀₎ or controlling so as not to exceed (V ₅ -V ₂₎
The display according to claim 1 or 2, wherein
Integrated tablet device. 11. Arrangement along different directions from each other.
A plurality of first electrodes and a plurality of second electrodes arranged in a row,
A pixel corresponding to the location where the first electrode and the second electrode intersect
The first panel and the first electrode and the second electrode are capacitively coupled to the first panel and the second electrode.
Instructing means for instructing the position of the surface from the first electrode side, first electrode driving means for driving the first electrode , second electrode driving means for driving the second electrode, first electrode driving means, and second electrode By controlling the driving means
Voltage corresponding to the element is applied to the first electrode and the second electrode.
A display control unit for setting a display period for displaying a desired image; and a first electrode driving unit for controlling a first electrode to sequentially apply a scanning voltage to the first electrode.
A first scanning period to be applied and a second electrode following the first scanning period
Controlling the driving means to sequentially apply a scanning voltage to the second electrode
Set the second scanning period and the time from the start of scanning
Detection control means for measuring the scanning voltage applied by the instruction means and the detection control means.
Induced voltage induced in the indicating means by capacitive coupling with
And the time measured by the detection control means.
Coordinate detection means for detecting the coordinates of the instruction means, and alternately switching between the display control means and the detection control means
Switching control means for controlling the detection voltage, wherein the detection control means includes an induced voltage induced by the instruction means.
Having the amplifier for amplifying the signal, and the indicating means during the second scanning period.
Of the induced voltage induced in the first scan
From the amplification factor of the induced voltage induced by the indicating means during the period.
A display-integrated tablet device characterized in that it is also large. 12. Arrangement along different directions from each other.
A plurality of first electrodes and a plurality of second electrodes arranged in a row,
A pixel corresponding to the location where the first electrode and the second electrode intersect
The first panel and the first electrode and the second electrode are capacitively coupled to the first panel and the second electrode.
Instructing means for instructing the position of the surface from the first electrode side, first electrode driving means for driving the first electrode , second electrode driving means for driving the second electrode, first electrode driving means, and second electrode By controlling the driving means
Voltage corresponding to the element is applied to the first electrode and the second electrode.
A display control unit for setting a display period for displaying a desired image; and a first electrode driving unit for controlling a first electrode to sequentially apply a scanning voltage to the first electrode.
A first scanning period to be applied and a second electrode following the first scanning period
Controlling the driving means to sequentially apply a scanning voltage to the second electrode
Set the second scanning period and the time from the start of scanning
Detection control means for measuring the scanning voltage applied by the instruction means and the detection control means.
Induced voltage induced in the indicating means by capacitive coupling with
And the time measured by the detection control means.
Coordinate detection means for detecting the coordinates of the instruction means, and alternately switching between the display control means and the detection control means
Switching control means for controlling the peak value of the scanning voltage applied to the second electrode during the second scanning period.
From the peak value of the scanning voltage applied to the first electrode during the first scanning period
Display-integrated tablet device
Place. 13. Arranged along different directions from each other.
A plurality of first electrodes and a plurality of second electrodes arranged in a row;
A pixel corresponding to the location where the first electrode and the second electrode intersect
The first panel and the first electrode and the second electrode are capacitively coupled to the first panel and the second electrode.
Instructing means for instructing the position of the surface, first electrode driving means for driving the first electrode, second electrode driving means for driving the second electrode, and controlling the first electrode driving means and the second electrode driving means And each picture
Voltage corresponding to the element is applied to the first electrode and the second electrode.
A display control unit for setting a display period for displaying a desired image; and a first electrode driving unit for controlling a first electrode to sequentially apply a scanning voltage to the first electrode.
A first scanning period to be applied and a second electrode following the first scanning period
Controlling the driving means to sequentially apply a scanning voltage to the second electrode
Set the second scanning period and the time from the start of scanning
Detection control means for measuring the scanning voltage applied by the instruction means and the detection control means.
Induced voltage induced in the indicating means by capacitive coupling with
And the time measured by the detection control means.
Coordinate detection means for detecting the coordinates of the instruction means, and alternately switching between the display control means and the detection control means
Switching control means for controlling the number of the second electrodes for applying the scanning voltage during the second scanning period.
From the number of first electrodes to which a scanning voltage is applied during the first scanning period
A display-integrated tablet device characterized in that it is also large. 14. A method according to claim 1, further comprising:
A plurality of first electrodes and a plurality of second electrodes arranged at regular intervals
Corresponding to the location where the first electrode and the second electrode intersect.
A display panel having a plurality of pixels, and the display panel is capacitively coupled to the first electrode and the second electrode.
Instructing means for instructing the position of the surface, first electrode driving means for driving the first electrode, second electrode driving means for driving the second electrode, and controlling the first electrode driving means and the second electrode driving means And each picture
Voltage corresponding to the element is applied to the first electrode and the second electrode.
A display control unit for setting a display period for displaying a desired image; and a first electrode driving unit for controlling a first electrode to sequentially apply a scanning voltage to the first electrode.
A first scanning period to be applied and a second electrode following the first scanning period
Controlling the driving means to sequentially apply a scanning voltage to the second electrode
Set the second scanning period and the time from the start of scanning
And a high frequency component for each scanning voltage in the first scanning period and the second scanning period.
High-frequency generation control means for superimposing the component, the scanning voltage applied by the instruction means and the detection control means
High-frequency component induced by the indicator means due to capacitive coupling with
Induction voltage including minute and time measured by the above detection control means
Coordinate detecting means for detecting the coordinates of the pointing means based on
And alternately switching between the display control means and the detection control means
Switching control means for controlling
Integral tablet device. 15. The high frequency generation control means according to claim 1, wherein
High frequency component superimposed on the scanning voltage applied to the first electrode during the period.
And the scanning applied to the second electrode during the second scanning period.
Different from the second frequency of the high frequency component superimposed on the scanning voltage
And the coordinate detecting means sets the first frequency and the second frequency
The wave number is separated and extracted from the induced voltage induced by the indicator.
Extraction means for extracting the extracted high-frequency component and the above-mentioned detection.
Based on the application timing measured by the output control means.
2. The method according to claim 1, wherein said detecting means detects coordinates.
5. The display-integrated tablet device according to 4. 16. The first frequency and the second frequency are odd with each other.
A contract characterized by being set to a frequency other than several times
The display-integrated tablet device according to claim 15. 17. A method according to claim 17, wherein the points are along different directions.
A plurality of first electrodes and a plurality of second electrodes arranged at regular intervals
Corresponding to the location where the first electrode and the second electrode intersect.
A display panel having a plurality of pixels, and the display panel is capacitively coupled to the first electrode and the second electrode.
And instruction means for instructing a position of the surface, and a first electrode driving means for driving the first electrode, and a second electrode driving means for driving the second electrode, corresponding to each pixel by controlling the first electrode drive means Voltage
Apply to one electrode sequentially and control the second electrode driving means
And apply a voltage corresponding to each pixel to the second electrode to
A display control means for setting a display period for displaying an image, and a high-frequency component applied to a voltage corresponding to each pixel on the first electrode in the display period.
High-frequency generation control means for superimposing the voltage on the first electrode during the display period;
Detection system that measures the application timing of each high-frequency component
Controlling means and the second electrode driving means to sequentially apply a scanning voltage to the second electrode.
Set the scanning period to be applied, and mark each scanning voltage.
Second detection control means for measuring the application timing, and the high-frequency power applied by the instruction means and the first detection control means.
High frequency induced in the indicating means by capacitive coupling with pressure
Extraction means for extracting high frequency components from the induced voltage containing the components
And the extracted high-frequency component and the time measured by the first detection control means.
Between the application timing and the instruction means and the second detection control means.
By the capacitive coupling with the applied scanning voltage,
The induced voltage including the induced voltage is measured by the second detection control means.
Detecting the coordinates of the pointing means based on the applied timing
Alternately switch between the coordinate detecting means for performing the above, and the display controlling means and the detecting controlling means.
Switching control means for controlling
Integral tablet device. 18. The liquid crystal display panel according to claim 18, wherein said display panel is a liquid crystal display panel.
Claim 11, Claim 12, Claim 1
3, Claim 14, Claim 15, Claim 16, or Claim
Item 18. A display-integrated tablet device according to item 17.