JPH10269020A - Liquid crystal display device with coordinate detection function and drive circuit of the display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the shielding effect due to a counter electrode and to detect the coordinates with high accuracy, by using an active matrix type liquid crystal panel of a lateral field system including the pixel electrodes and their counter electrodes on an array substrate. SOLUTION: An active matrix type liquid crystal panel of a horizontal field system where the pixel electrodes H and their counter electrodes C are placed on an array substrate is used. The array substrate consists of a switching element(TFT) 7, a scan electrode G, a signal electrode S, a counter electrode C' connected to the electrodes C, and the electrodes H. In such a constitution, a display selection pulse is applied to the electrode G to set the TFT 7 in a conductive state in a display period. Thus, the image signals applied to the electrode S are applied to the electrodes H via the TFT 7. Then, the orientation states of liquid crystal molecules are changed according to the difference of potentials between both electrodes H and C. As a result, a screen is displayed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device having a coordinate detecting function in which a tablet for inputting coordinates is integrated with a matrix type display, and a driving circuit therefor.

[0002]

2. Description of the Related Art This type of conventional liquid crystal display device with a coordinate detection function is configured as shown in a block diagram of FIG. In FIG. 11, 1 is a liquid crystal panel, 2 is a detection pen,
Reference numeral 3 denotes a scan electrode drive circuit, 4 denotes a signal electrode drive circuit, 5 denotes a detection unit, 6 denotes a control unit, R (1 to m) denotes scan electrodes, and S (1 to n) denotes signal electrodes. FIG. 12 is a diagram showing the principle and timing of coordinate detection. Reference numeral 2 denotes a detection pen, r1 to r10, S
1 is each electrode of the liquid crystal panel, C1 to C10 (Ca) are capacitance coupling generated between the detection pen 2 and the electrodes r1 to r10 (S1), P1 to P7 are detection scanning pulses, and D1 is a detection signal waveform. , D2 are differential waveforms of the detection signal waveform D1.

Conventionally, in a liquid crystal display device having a coordinate detection function for performing coordinate detection using each electrode of a liquid crystal panel as it is, a display period and a detection period are provided in one vertical scanning period (one frame). When a detection scanning pulse is sequentially applied to each of the scanning electrodes and signal electrodes of the liquid crystal panel, the detection pen 2 is brought into close proximity to the liquid crystal panel and the detection pen is connected via the capacitive coupling generated between the electrodes of the liquid crystal panel. 2, a detection signal waveform D1 based on the detection scanning pulse is detected, and the coordinate position is determined from the detection timing.

FIG. 13 is a timing chart of signals for coordinate detection in the liquid crystal display device with a coordinate detection function shown in FIG. In FIG. 13, Vp is a detection signal waveform detected by the detection pen 2, and dVp / dt is a differential waveform of the detection signal waveform Vp. The position of the detection pen 2 is determined from the time when the detection signal waveform Vp shown in FIG. 13 reaches a peak or the time when the differential waveform dVp / dt becomes zero.

[0005] The above-described liquid crystal display device with a coordinate detection function mainly describes a method of realizing a simple matrix type liquid crystal display device. Recently, a method of realizing the method using an active matrix type liquid crystal display device has been devised. Even in the case of realizing the active matrix type liquid crystal display device, the basic principle is the same as that of the simple matrix type liquid crystal display device. However, in the case of a conventional liquid crystal panel of an active matrix type liquid crystal display device, there are structural restrictions.
Hereinafter, a method of realizing a case where a liquid crystal panel of an active matrix type liquid crystal display device is used will be described.

The operation period is the same as that of the liquid crystal panel of the simple matrix type display device. One frame is divided into a display period and a detection period, and the display operation is performed during the display period and the detection operation is performed during the detection period. Further, the detection period is divided into an X coordinate (row direction) detection period and a Y coordinate (column direction) detection period, and a detection scan pulse is sequentially applied to the scan electrodes and the signal electrodes. A signal is detected via the capacitance between each electrode to which the detection scanning pulse is applied and the detection pen, and the X and Y coordinate values are determined based on the detection timing of the signal. However, a liquid crystal panel of a conventional active matrix type liquid crystal display device generally has the following restrictions.

FIG. 14 is a view showing a structure of a liquid crystal panel of a conventional active matrix type liquid crystal display device. As shown in FIG. 14, switching elements (TFTs) 7 corresponding to respective intersections of the signal electrodes S and the scanning electrodes R arranged in a matrix.
And an array substrate 8 on which the pixel electrodes H connected to the switching elements 7 are arranged. Further, a counter electrode C is generally disposed as a solid electrode on a counter substrate 9 disposed to face the array substrate 8. This liquid crystal panel has a structure in which an opposing substrate 9 is arranged on the front surface and an array substrate 8 is arranged on the back surface. With such an arrangement, the counter electrode C
Will shield the signals from the scanning electrodes R and the signal electrodes S, so that the detection signal cannot be sufficiently obtained with the detection pen. When the surface of the array substrate 8 is turned upside down to obtain a sufficient detection signal, there are reflections of the switching element 7, the scanning electrode R, and the signal electrode S. In order to prevent this, it is necessary to provide a black matrix layer for preventing reflection on the wiring of each electrode and the switching element 7.

[0008]

In the liquid crystal panel of the active matrix type liquid crystal display device used in the liquid crystal display device having the coordinate detecting function, signals from the respective electrodes of the liquid crystal panel are shielded by the counter electrode. As a result, there is a problem that it becomes weak and it is difficult to detect with a detection pen. Further, even when the array surface of the liquid crystal panel is on the front side, there is a problem that the black matrix layer must be provided in order to prevent the reflection of the wiring of each electrode and the switching element or the reflection.

SUMMARY OF THE INVENTION The present invention is directed to solving the above-mentioned problems of the prior art, and employs a liquid crystal panel of an in-plane switching type active matrix type liquid crystal display device to reduce a shielding effect by a counter electrode. Accordingly, an object of the present invention is to provide a liquid crystal display device with a coordinate detection function capable of detecting coordinates with higher accuracy and a driving circuit thereof.

[0010]

In order to achieve this object, a liquid crystal display device with a coordinate detecting function according to the present invention is provided with a plurality of signal electrodes and scanning electrodes arranged in a matrix and corresponding to their intersections. A switching element provided, a comb-shaped pixel electrode connected to the switching element, and an array substrate having a counter electrode connected to a counter electrode wiring formed in engagement with the pixel electrode and parallel to each scanning electrode;
An opposing substrate disposed opposite to the array substrate; an active matrix type liquid crystal panel including a liquid crystal layer sandwiched between the array substrate and the opposing substrate; and voltages applied to the scanning electrodes, signal electrodes, and opposing electrodes of the liquid crystal panel. Each of the driving means to be applied, a detection conductor for detecting a signal through a capacitive coupling generated between a scanning electrode and a signal electrode when approaching the liquid crystal panel, and a signal detected through the detection conductor. And detecting means for detecting the position of the detecting conductor.

[0011] In addition, a detection conductor for detecting a signal via a capacitive coupling generated between the counter electrode and the signal electrode when approaching the liquid crystal panel is provided.

The drive circuit of the liquid crystal display device having the coordinate detection function includes a scan signal for designating a scan electrode to which a display selection pulse is applied during a display period, and a scan electrode for applying a detection scan pulse during a detection period. And a shift register for sequentially shifting and outputting a selection signal for designating the voltage, and selecting means for selecting a designated voltage according to the output of the shift register and applying the selected voltage to the scan electrode.

Further, the shift register sequentially shifts and outputs a selection signal for designating the counter electrode wiring to which a detection scanning pulse is applied during a detection period, and the selection means responds to an output of the shift register. A specified voltage is selected and applied to the counter electrode wiring.

The shift register sequentially shifts a selection signal for designating a scan electrode to which a display selection pulse is applied in a display period, and designates a counter electrode wiring to which a detection scan pulse is applied in a detection period. The selection signal is sequentially shifted and output, and the selection means selects a voltage specified according to the output of the shift register during the display period, applies the selected voltage to the scan electrode, and specifies the voltage according to the output of the shift register during the detection period. The selected voltage is selected and applied to the counter electrode wiring.

According to the first aspect of the present invention, the counter electrode is provided on the array substrate of the liquid crystal panel, so that the shielding effect by the counter electrode between the detection conductor and the liquid crystal panel is reduced. Can be.

According to the second aspect of the present invention,
Since the counter electrode is arranged in the pixel portion of the array substrate, by using the counter electrode having a capacitance larger than the scanning electrode in the capacitive coupling with the detection conductor, the counter electrode is caused to scan with the detection scanning pulse. It can be detected with high accuracy.

According to the third aspect of the present invention,
By setting the voltage value of the detection scanning pulse to a value at which the switching element does not become conductive, it is possible to prevent a signal irrelevant to the pixel electrode from being applied.

According to the fourth or fifth aspect of the present invention, by inverting the polarity of the detection scanning pulse every one vertical scanning period, the applied signal can be converted into an alternating current.

According to the sixth aspect of the present invention,
Each voltage applied to the scanning electrode can be selected in the display period and the detection period.

According to the seventh aspect of the present invention,
The detection scan pulse can be applied to the counter electrode only during the detection period.

According to the eighth aspect of the present invention,
A shift register that specifies a scan electrode to which a display selection pulse is applied during a display period can also be used as a shift register that specifies a counter electrode wiring to which a detection scan pulse is applied during a detection period.

According to the ninth or tenth aspect of the present invention, by inverting the polarity of the detection scanning pulse every vertical scanning period, the applied signal can be converted into an alternating current.

[0023]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a partial plan view showing a pattern configuration of each electrode of an array substrate used in a liquid crystal panel of a liquid crystal display device with a coordinate detection function according to an embodiment of the present invention. Here, components having substantially the same functions and corresponding to the components described in FIG. 14 showing the conventional example are denoted by the same reference numerals. In FIG. 1, reference numeral 7 denotes a switching element (TFT), G denotes a scanning electrode, S denotes a signal electrode, C denotes a counter electrode, C ′ denotes a counter electrode wiring to which the counter electrode C is connected, and H denotes a pixel electrode. In the array substrate having such a configuration, when a display selection pulse for making the TFT 7 conductive is applied to the scanning electrode G during the display period, the image signal applied to the signal electrode S through the TFT 7 is applied to the pixel electrode H. Applied. According to the potential difference between the pixel electrode H and the counter electrode C, the alignment state of the liquid crystal molecules changes, and the screen is displayed.

FIG. 2 is a block diagram showing a schematic configuration of the liquid crystal display device with a coordinate detection function according to the first embodiment of the present invention. Here, the same reference numerals are given to components corresponding to the components described in FIG. 11 of the conventional example, and the same applies to the following drawings. 2, reference numeral 1 denotes a liquid crystal panel having the array substrate shown in FIG. 1, 2 denotes a detection pen which is a detection conductor, 4 denotes a signal electrode driving circuit, and 5 denotes a change in a detection signal from the detection pen 2. A detection unit, 6 a control unit for controlling the detection unit 5 and each drive circuit, 10 a scan electrode drive circuit, 11 a counter electrode drive circuit, G (1 to m) scan electrodes,
S (1 to n) is a signal electrode, and C (1 to m) is a counter electrode.

FIG. 3 is a timing chart showing signals for coordinate detection of the liquid crystal display device with a coordinate detection function according to the first embodiment. As shown in FIG. 3, one frame is provided with a display period for performing a display operation and a detection period for performing a detection operation. FIG. 4 is a block diagram showing a configuration of a scan electrode drive circuit used in the liquid crystal display device with a coordinate detection function according to the first embodiment. In FIG. 4, reference numeral 12 denotes a shift register for sequentially shifting a selection signal designating a scanning electrode G to which a display selection pulse is applied, 13 denotes a switching circuit as selection means, and SW1 denotes a voltage between a display period and a detection period of the display selection pulse. A first selection circuit for selecting a level,
SW2 is a second selection circuit for selecting an output voltage to the scanning electrode G, Q (1 to m) is an output of the shift register 12, G (1 to m) is a scanning electrode, and Vs is a detection scanning pulse applied in a detection period. The voltage applied to the scanning electrode G, Von, is the scanning electrode G
Applied when the TFT is turned on,
Voff is a voltage applied to the scan electrode G when the TFT is not turned on, SEL is a signal indicating a display period and a detection period, CLK is a transfer clock of the shift register, and FS is a selection signal which is data of the shift register.

In the display period of one frame, SEL is set to “H”, a selection signal FS is input to the shift register 12 of the scan electrode drive circuit shown in FIG. 4, and the shift is performed in synchronization with the input transfer clock CLK. The data is sequentially shifted by the register 12. When the output Q of the shift register 12 is "H", SW1 outputs Von, and SW2 outputs Son to the scan electrode G.
When the output of W1 is applied and the output Q of the shift register 12 is "L", switching is performed so as to apply Voff to the scanning electrode G, and a display selection pulse is sequentially applied to the scanning electrode G as shown in FIG. A signal corresponding to the display image data is applied to the signal electrode S in synchronization with the display selection pulse. Further, a counter voltage is applied to the counter electrode C. With these operations, display is performed by changing the alignment state of the liquid crystal molecules of the pixel.

In the next detection period, SEL is set to "L", a selection signal FS is input to the shift register 12 of the scan electrode drive circuit shown in FIG. 4, and the shift is performed in synchronization with the input transfer clock CLK. By register 12,
The selection signal is sequentially shifted. When the output Q of the shift register 12 is "H", SW1 outputs Vs, SW2 applies the output of SW1 to the scan electrode G, and when the output Q of the shift register 12 is "L", Voff changes the scan electrode. The detection scan pulse is sequentially applied to the scan electrodes G in the row direction detection period as shown in FIG.

In this case, a detection scanning pulse is applied to a plurality of scanning electrodes G simultaneously to increase the intensity of the detection signal. Further, the voltage value of the detection scanning pulse needs to be a value that does not cause the TFT of the pixel to be in a conductive state. Capacitance coupling exists between the scanning electrode G and the detection pen 2 shown in FIG. 2, and when the detection scanning pulse approaches the position of the detection pen 2 on the liquid crystal panel 1, the detection signal waveform shown in FIG. The potential of the detection pen 2 changes like Vp, and becomes the maximum when approaching the closest. When the detection signal detected by the detection pen 2 is differentiated through a differentiating circuit, a differential waveform dVp /
dt, and the time when the differential waveform dVp / dt changes from positive to negative is detected by the detection unit 5 shown in FIG. 2. For example, the time difference from the time when the application of the detection scanning pulse to the scanning electrode G is started is calculated from the time difference. Is determined on which scanning electrode G of the liquid crystal panel the detection pen 2 is located.

Similarly, as shown in FIG. 3, a detection scanning pulse is also applied to the signal electrodes S sequentially in the column direction detection period. Also in this case, a detection scan pulse is applied to a plurality of signal electrodes S at the same time to increase the intensity of the detection signal. FIG.
Is present between the signal electrode S and the detection pen 2 and the signal electrode S is connected in the same manner as in the row direction detection period described above.
From the time difference from the start of application of the detection scanning pulse to the liquid crystal panel, it is determined on which signal electrode S the detection pen 2 is present on the liquid crystal panel.

Note that these output voltage levels are not limited to the combinations shown in the description of the first embodiment. Also, by inverting the detection scanning pulse for each frame, the DC applied to the liquid crystal by the detection scanning pulse is changed.
Ingredients can be eliminated.

FIG. 5 is a block diagram showing a schematic configuration of a liquid crystal display device with a coordinate detection function according to the second embodiment of the present invention. In FIG. 5, 1 is a liquid crystal panel, 2 is a pen for detection, 3 is a scan electrode drive circuit, 4 is a signal electrode drive circuit, 5
Is a detection unit, 6 is a control unit, 11 'is a counter electrode driving circuit, G
(1 to m) are scanning electrodes, S (1 to n) are signal electrodes, and C (1 to m)
Is a counter electrode. FIG. 6 is a timing chart showing signals for coordinate detection of the liquid crystal display device with a coordinate detection function according to the second embodiment. A display period for performing a display operation and a detection period for performing a detection operation are provided in one frame.

FIG. 7 is a block diagram showing the configuration of a counter electrode drive circuit used in the liquid crystal display device with a coordinate detection function according to the second embodiment. In FIG. 7, reference numeral 14 denotes a shift register for sequentially shifting a selection signal designating a counter electrode (counter electrode wiring) C to which a detection scanning pulse is applied, 15 a switching circuit, and SW a selection for selecting an output voltage to the counter electrode C. Circuit, Q (1-m) is the output of the shift register 14,
Vcom is the counter electrode C when no detection scan pulse is applied.
Is a voltage applied to the counter electrode C to which the detection scanning pulse is applied in the detection period, CLK is a transfer clock of the shift register, and FS is a selection signal which is data of the shift register.

In the display period of one frame, a display selection pulse is sequentially applied to the scanning electrodes G as shown in FIG.
A signal corresponding to the display image data is applied to the signal electrode S in synchronization with the display selection pulse. Further, in the counter electrode driving circuit shown in FIG.
Is output and applied to the counter electrode C. With these operations, display is performed by changing the alignment state of the liquid crystal molecules of the pixel.

Next, in the detection period, the selection signal FS is input to the shift register 14 of the counter electrode driving circuit shown in FIG. 7, and the selection signal is sequentially shifted by the shift register 14 in synchronization with the input transfer clock CLK. Is done. SW
Selects Vs when the output Q from the shift register 14 is "H", and sequentially applies a detection scanning pulse to the counter electrode C in the row direction detection period as shown in FIG. in this case,
In order to increase the strength of the detection signal, a detection scan pulse is applied to a plurality of counter electrodes C at the same time. Counter electrode C shown in FIG.
When the detection scanning pulse approaches the position of the detection pen 2 on the liquid crystal panel 1, the potential of the detection pen 2 changes as shown in FIG. And
Maximum when approached most. When the detection signal waveform Vp detected by the detection pen 2 is differentiated through a differentiating circuit, a differentiated waveform dVp / dt as shown in FIG. 6 is obtained, and the time when the differentiated waveform changes from positive to negative is detected by the detection unit 5 in FIG. Then, for example, on which counter electrode C of the liquid crystal panel the detection pen 2 is located is determined from the time difference from the time when the application of the detection scanning pulse to the counter electrode C is started.

Similarly, detection scan pulses are sequentially applied to the signal electrodes S in the column direction detection period as shown in FIG.
Also in this case, a detection scan pulse is applied to a plurality of signal electrodes S at the same time to increase the intensity of the detection signal. Capacitive coupling exists between the signal electrode S and the detection pen 2 in FIG.
As in the description of the row direction detection period, the detection unit 5 detects a point in time when the detection signal waveform Vp and the differential waveform dVp / dt change from a maximum to a negative, as shown in FIG. From the time difference from when the application of the detection scanning pulse is started, it is determined on which signal electrode S of the liquid crystal panel the detection pen 2 is present.

Note that the driving circuit shown in FIG. 7 is merely an example, and its configuration changes depending on the driving method of the liquid crystal panel and the form of the detection scanning pulse, and it is sufficient that the output voltage can be changed between the display period and the detection period. Further, the output voltage level is not limited to the combination shown in the second embodiment. Further, by inverting the detection scanning pulse for each frame, the DC component applied to the liquid crystal by the detection scanning pulse can be eliminated.

FIG. 8 is a block diagram showing a schematic configuration of a liquid crystal display device with a coordinate detecting function according to the third embodiment of the present invention. 8, 1 is a liquid crystal panel, 2 is a detection pen, 4 is a signal electrode drive circuit, 5 is a detection unit, 6 is a control unit,
Reference numeral 16 denotes a scanning and counter electrode driving circuit, G (1 to m) denotes a scanning electrode, S (1 to n) denotes a signal electrode, and C (1 to m) denotes a counter electrode. FIG. 9 is a timing chart showing signals of coordinate detection of the liquid crystal display device with a coordinate detection function according to the third embodiment. A display period for performing a display operation and a detection period for performing a detection operation are provided in one frame.

FIG. 10 is a block diagram showing a configuration of a scanning and counter electrode driving circuit used in the liquid crystal display device with a coordinate detection function according to the third embodiment. In FIG. 10, reference numeral 17 denotes a shift register for sequentially shifting a selection signal designating a scanning electrode or a counter electrode to which a detection scanning pulse is applied, 18 a switching circuit, and SW1 a first selection circuit for selecting an output voltage to the scanning electrode G. , SW2 is a second selection circuit for selecting the output voltage to the common electrode C, Q (1 to m) is the output of the shift register 17, Vcom is the voltage applied to the common electrode C when no detection scan pulse is applied, and Vs Is a voltage applied to the counter electrode C to which the detection scanning pulse is applied in the detection period, Von is a voltage applied to the scanning electrode G when the TFT is turned on, and Voff is applied to the scanning electrode G and the TFT is not turned on. Sometimes applied voltage, SEL
Is a signal indicating a display period and a detection period, CLK is a transfer clock of the shift register, and FS is a selection signal which is data of the shift register.

In the display period of one frame, SEL is set to “H”, and the selection signal FS is input to the shift register 17 of the scanning and counter electrode driving circuit shown in FIG. 10, and is synchronized with the input transfer clock CLK. Shift register
17 sequentially. SW1 is shift register 17
When the output Q of the shift register 17 is "H", Von is applied to the scanning electrode G, and when the output Q of the shift register 17 is "L", switching is performed so as to apply Voff to the scanning electrode G. As a result of this operation, a display selection pulse is sequentially applied to the scanning electrodes G as shown in FIG. A signal corresponding to the display image data is applied to the signal electrode S in synchronization with the display selection pulse. Also,
In the display period, SW2 always selects Vcom, and Vcom is applied to the counter electrode C.

Next, during the detection period, SEL is set to “L”, and the selection signal FS is input to the shift register 17 of the scanning and counter electrode driving circuit shown in FIG. 10, and is synchronized with the input transfer clock CLK. The selection signal is sequentially shifted by the shift register 17. SW1 selects Voff in the detection period, and Voff is applied to the scanning electrode G. SW2 switches so that Vs is applied to the counter electrode C when the output Q of the shift register 17 is "H", and Vcom is applied to the counter electrode C when the output Q of the shift register 17 is "L". As a result of this operation, as shown in FIG.
The detection scanning pulse is sequentially applied as in the row direction detection period shown by. In this case, to increase the strength of the detection signal, a detection scanning pulse is simultaneously applied to the plurality of counter electrodes C.

Capacitance coupling exists between the counter electrode C and the detection pen 2 shown in FIG.
When the detection scanning pulse approaches the position (2), the potential of the detection pen 2 changes as shown in FIG. When the detection signal waveform Vp detected by the detection pen 2 is differentiated through a differentiating circuit, a differential waveform dVp as shown in FIG.
/ Dt, and the time when the differential waveform changes from positive to negative is detected by the detection unit 5 in FIG. 8. For example, the detection pen is determined based on the time difference from the time when the application of the detection scanning pulse to the scanning electrode G is started. 2 is located on which scanning electrode G of the liquid crystal panel 1.

Similarly, a detection scan pulse is sequentially applied to the signal electrodes S as in the column direction detection period shown in FIG. Also in this case, a detection scan pulse is applied to a plurality of signal electrodes simultaneously to increase the intensity of the detection signal. Capacitance coupling exists between the signal electrode S and the detection pen 2, and the detection signal of the detection pen 2 is detected by the detection unit 5 as described in the row direction detection period. From the time difference from when the application of the detection scanning pulse is started, it is determined on which signal electrode of the liquid crystal panel the detection pen 2 is present.

Note that the driving circuit shown in FIG. 10 is also an example, and its configuration changes depending on the driving method of the liquid crystal panel, the voltage value of the detection scanning pulse, and the like. Further, the shift register 17 may operate as a shift register of the scan electrode driving circuit in the display period, and may operate as a shift register of the counter electrode driving circuit in the detection period. Further, the output voltage level is not limited to the combination shown in the third embodiment, and the DC component applied to the liquid crystal by the detection scan pulse can be eliminated by inverting the detection scan pulse for each frame. Can be.

As described above, according to the liquid crystal display device with the coordinate detection function and the driving circuit of the present invention, the conventional active electrode in which the pixel electrode is arranged on the array substrate and the opposing electrode is arranged on the substrate opposed thereto. Like a liquid crystal display device with a coordinate detection function that employs a matrix type liquid crystal panel, there is no shielding by the counter electrode between the detection pen and the electrode to which the detection scan pulse is applied, and the strength of the signal detected by the detection pen Therefore, more accurate coordinate detection can be performed. Also, due to the structure of the horizontal electric field type liquid crystal panel,
Since the counter electrode also exists in the pixel, by using the counter electrode as a detection electrode, it is possible to obtain a larger coupling capacitance between the detection electrode and the detection pen,
The strength of the detected signal can be increased.

[0045]

As described above, according to the first aspect of the present invention,
According to the configuration described above, in a liquid crystal display device having a coordinate detection function, a conventional electric field detection type liquid crystal display device employing a horizontal electric field type active matrix type liquid crystal panel having a pixel electrode and a counter electrode arranged on its array substrate is used. Unlike a liquid crystal display device, there is no shield between the detection pen and the electrode to which the detection scanning pulse is applied, because there is no shield by the counter electrode, and the intensity of the signal detected by the detection pen can be increased, so that more accurate coordinates can be obtained. Detection can be performed.

According to the configuration of the second aspect of the present invention, since the liquid crystal panel is of a horizontal electric field type, the counter electrode is also present in the pixel, and the counter electrode is used as an electrode for detection. By doing so, it is possible to increase the coupling capacitance between the detection electrode and the detection pen, and it is possible to increase the intensity of the signal detected by the detection pen.

According to the third, fourth or fifth aspect of the present invention, the voltage value of the detection scanning pulse is set to a value at which the TFT does not become conductive, and the polarity of the detection scanning pulse is inverted every frame. By doing so, a signal irrelevant to the pixel electrode is not applied, and the DC component of the applied signal can be eliminated.

According to a sixth aspect of the present invention, in a driving circuit of a liquid crystal display device having a coordinate detecting function,
Each voltage applied to the scanning electrode can be selected in the display period and the detection period for each frame, and according to the configuration of claim 7, the detection scanning pulse can be applied to the counter electrode only in the detection period. According to the configuration of the eighth aspect, the display selection pulse can be switched to the scan electrode during the display period, and the detection scan pulse can be switched and applied to the counter electrode (counter electrode wiring) during the detection period, regardless of the pixel electrode. A shift register can be shared without a signal being applied, and peripheral circuits can be reduced.

Further, according to the ninth or tenth aspect of the present invention, there is an effect that the polarity of the detection scanning pulse is inverted for each frame and the DC component of the applied signal can be eliminated. .

[Brief description of the drawings]

FIG. 1 is a partial plan view showing a pattern configuration of each electrode of an array substrate used in a liquid crystal panel of a liquid crystal display device with a coordinate detection function according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a schematic configuration of a liquid crystal display device with a coordinate detection function according to the first embodiment of the present invention.

FIG. 3 is a timing chart showing signals of coordinate detection of the liquid crystal display device with a coordinate detection function according to the first embodiment.

FIG. 4 is a block diagram illustrating a configuration of a scan electrode drive circuit used in the liquid crystal display device with a coordinate detection function according to the first embodiment.

FIG. 5 is a block diagram illustrating a schematic configuration of a liquid crystal display device with a coordinate detection function according to a second embodiment of the present invention.

FIG. 6 is a timing chart showing signals of coordinate detection of the liquid crystal display device with a coordinate detection function according to the second embodiment.

FIG. 7 is a block diagram showing a configuration of a counter electrode drive circuit used in the liquid crystal display device with a coordinate detection function according to the second embodiment.

FIG. 8 is a block diagram illustrating a schematic configuration of a liquid crystal display device with a coordinate detection function according to a third embodiment of the present invention.

FIG. 9 is a timing chart showing signals of coordinate detection of the liquid crystal display device with a coordinate detection function according to the third embodiment.

FIG. 10 is a block diagram showing a configuration of a scanning and counter electrode driving circuit used in the liquid crystal display device with a coordinate detection function according to the third embodiment.

FIG. 11 is a block diagram showing a schematic configuration of a conventional liquid crystal display device with a coordinate detection function.

FIG. 12 is a diagram illustrating the principle and timing of coordinate detection.

FIG. 13 is a timing chart of signals for coordinate detection in a conventional liquid crystal display device with a coordinate detection function.

FIG. 14 is a view showing a structure of a liquid crystal panel of a conventional active matrix type liquid crystal display device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Liquid crystal panel, 2 ... Pen for detection, 3/10 ... Scan electrode drive circuit, 4 ... Signal electrode drive circuit, 5 ... Detection part,
6: control unit, 7: TFT, 8: array substrate, 9
... counter substrate, 11, 11 '... counter electrode drive circuit, 12, 1
4, 17 ... shift register, 13, 15, 18 ... switching circuit, 16 ... scanning and counter electrode drive circuit.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Satoshi Asada 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (10)

[Claims] 1. A plurality of signal electrodes and scanning electrodes arranged in a matrix and a switching element provided corresponding to each intersection thereof; a comb-shaped pixel electrode connected to the switching element; An array substrate having an opposing electrode formed to engage and connected to an opposing electrode wiring parallel to each scanning electrode; an opposing substrate disposed opposite to the array substrate; An active matrix type liquid crystal panel comprising a held liquid crystal layer; driving means for applying a voltage to a scanning electrode, a signal electrode, and a counter electrode of the liquid crystal panel; and the scanning electrode when approaching the liquid crystal panel And a detection conductor for detecting a signal through a capacitive coupling generated between the detection conductor and the signal electrode, and detecting the signal from the signal detected through the detection conductor. A detecting means for detecting a position, wherein one vertical scanning period includes a display period and a detection period, and in the display period, a display selection pulse for turning on the switching element is sequentially applied to the scanning electrode, and the display is performed. Applying an image signal corresponding to the display image data to the signal electrode in synchronization with the selection pulse, writing the image signal to the pixel electrode through the switching element, between the pixel electrode and the counter electrode, the array substrate and By generating an electric field that is substantially parallel to the counter substrate, the arrangement of liquid crystal molecules is changed to display display image data. During the detection period, a detection scan pulse is sequentially applied to the scan electrode and the signal electrode. A capacitance formed between the detection conductor and the scanning electrode and the signal electrode when the detection conductor is brought close to the liquid crystal panel; Detecting a change in the voltage generated in the detection conductor via the detection conductor, and detecting a position of the detection conductor on the liquid crystal panel from the time when the change is detected. Liquid crystal display. 2. A plurality of signal electrodes and scanning electrodes arranged in a matrix and a switching element provided corresponding to each intersection thereof, a comb-shaped pixel electrode connected to the switching element, and An array substrate having an opposing electrode formed to engage and connected to an opposing electrode wiring parallel to each scanning electrode; an opposing substrate disposed opposite to the array substrate; An active matrix type liquid crystal panel comprising a liquid crystal layer held therein; driving means for applying a voltage to a scanning electrode, a signal electrode and a counter electrode of the liquid crystal panel; and the counter electrode when approaching the liquid crystal panel And a detection conductor for detecting a signal through a capacitive coupling generated between the detection conductor and the signal electrode, and detecting the signal from the signal detected through the detection conductor. A detecting means for detecting a position, wherein one vertical scanning period includes a display period and a detection period, and in the display period, a display selection pulse for turning on the switching element is sequentially applied to the scanning electrode, and the display is performed. Applying an image signal corresponding to the display image data to the signal electrode in synchronization with the selection pulse, writing the image signal to the pixel electrode through the switching element, between the pixel electrode and the counter electrode, the array substrate and By generating an electric field substantially parallel to the counter substrate, the arrangement of the liquid crystal molecules is changed to display display image data. During the detection period, a detection scan pulse is sequentially applied to the counter electrode and the signal electrode. A capacitance formed between the detection conductor and the counter electrode and the signal electrode when the detection conductor is brought close to the liquid crystal panel; A coordinate detecting function for detecting a change in the voltage generated in the detection conductor via the detection conductor, and detecting a position of the detection conductor on the liquid crystal panel from the time when the change is detected. Liquid crystal display. 3. The voltage value of a detection scan pulse applied to a scan electrode during the detection period is a value at which a switching element does not become conductive.
A liquid crystal display device with a coordinate detection function according to the description. 4. The liquid crystal display device with a coordinate detection function according to claim 1, wherein the polarity of the detection scanning pulse applied to the scanning electrode is inverted every vertical scanning period during the detection period. 5. The liquid crystal display device with a coordinate detection function according to claim 2, wherein during the detection period, the polarity of the detection scanning pulse applied to the counter electrode is inverted every vertical scanning period. 6. A plurality of signal electrodes and scanning electrodes arranged in a matrix and a switching element provided corresponding to each intersection thereof, a comb-shaped pixel electrode connected to the switching element, and An array substrate having opposing electrodes connected to opposing electrode wirings formed in an occlusal manner and wired in parallel with the respective scanning electrodes; an opposing substrate arranged opposite to the array substrate; An active matrix type liquid crystal panel including a liquid crystal layer sandwiched between substrates is provided. One vertical scanning period includes a display period and a detection period, and the display period includes a display selection pulse for turning on the switching element. Are sequentially applied to the scanning electrode, and an image signal corresponding to display image data is applied to the signal electrode in synchronization with the display selection pulse, and the switching element Write the image signal to the pixel electrode through, between the pixel electrode and the counter electrode, the array substrate and the counter substrate, by generating a substantially parallel electric field, to change the arrangement of liquid crystal molecules, Displaying the display image data, the detection period, the detection scan pulse is sequentially applied to the scan electrode and the signal electrode, and when the detection conductor is brought close to the liquid crystal panel, the detection conductor and the scan electrode and A change in the voltage generated in the detection conductor is detected through capacitive coupling generated between the signal electrode and the signal electrode. From the time when the change is detected, the position of the detection conductor on the liquid crystal panel is detected. In the liquid crystal display device having a coordinate detection function for detecting the scan signal, a selection signal for designating the scan electrode to which the display selection pulse is applied is sequentially shifted during the display period, In the period, a shift register for sequentially shifting and outputting a selection signal for designating the scan electrode to which the detection scan pulse is applied, and a voltage designated according to an output of the shift register are selected, and the scan is performed. A driving circuit for a liquid crystal display device with a coordinate detection function, comprising a selection means for applying the voltage to an electrode. 7. A plurality of signal electrodes and scanning electrodes arranged in a matrix and a switching element provided corresponding to each intersection thereof, a comb-shaped pixel electrode connected to the switching element, and An array substrate having opposing electrodes connected to opposing electrode wirings formed in an occlusal manner and wired in parallel with the respective scanning electrodes; an opposing substrate arranged opposite to the array substrate; An active matrix type liquid crystal panel including a liquid crystal layer sandwiched between substrates is provided. One vertical scanning period includes a display period and a detection period, and the display period includes a display selection pulse for turning on the switching element. Are sequentially applied to the scanning electrode, and an image signal corresponding to display image data is applied to the signal electrode in synchronization with the display selection pulse, and the switching element Write the image signal to the pixel electrode through the pixel electrode and generate an electric field substantially parallel to the array substrate and the counter substrate between the pixel electrode and the counter electrode, thereby changing the arrangement of the liquid crystal molecules. Displaying the display image data, and applying the detection scanning pulse to the counter electrode and the signal electrode sequentially during the detection period, and bringing the detection conductor and the counter electrode when the detection conductor approaches the liquid crystal panel. And a change in the voltage generated in the detection conductor via the capacitive coupling generated between the detection conductor and the signal electrode, and from the time when the change is detected, the detection conductor on the liquid crystal panel is detected. In the liquid crystal display device having a coordinate detection function for detecting a position, in the detection period, a selection signal for designating the counter electrode wiring to which the detection scan pulse is applied is sequentially shifted. A shift register for outputting, to select the specified voltage according to the output of the shift register, the driving circuit of the coordinate detection-capable liquid crystal display device characterized by comprising a selection means for applying to the counter electrode wiring. 8. A plurality of signal electrodes and scanning electrodes arranged in a matrix and switching elements provided corresponding to intersections thereof, comb-shaped pixel electrodes connected to the switching elements, and An array substrate having opposing electrodes connected to opposing electrode wirings formed in an occlusal manner and wired in parallel with the respective scanning electrodes; an opposing substrate arranged opposite to the array substrate; An active matrix type liquid crystal panel including a liquid crystal layer sandwiched between substrates is provided. One vertical scanning period includes a display period and a detection period, and the display period includes a display selection pulse for turning on the switching element. Are sequentially applied to the scanning electrode, and an image signal corresponding to display image data is applied to the signal electrode in synchronization with the display selection pulse, and the switching element Write the image signal to the pixel electrode through the pixel electrode and generate an electric field substantially parallel to the array substrate and the counter substrate between the pixel electrode and the counter electrode, thereby changing the arrangement of the liquid crystal molecules. Displaying the display image data, and applying the detection scanning pulse to the counter electrode and the signal electrode sequentially during the detection period, and bringing the detection conductor and the counter electrode when the detection conductor approaches the liquid crystal panel. And a change in the voltage generated in the detection conductor via the capacitive coupling generated between the detection conductor and the signal electrode, and from the time when the change is detected, the detection conductor on the liquid crystal panel is detected. In the liquid crystal display device with a coordinate detection function for detecting a position, in the display period, a selection signal for designating the scan electrode to which the display selection pulse is applied is sequentially shifted, In the detection period, a shift register that sequentially shifts and outputs a selection signal for designating the counter electrode wiring to which the detection scan pulse is applied, and in the display period, the shift register is designated according to the output of the shift register. Selecting means for selecting the applied voltage to the scan electrode, and selecting a voltage specified according to the output of the shift register and applying the selected voltage to the counter electrode wiring during the detection period. Circuit for a liquid crystal display device with a coordinate detection function. 9. The driving circuit for a liquid crystal display device with a coordinate detection function according to claim 6, wherein in the detection period, the polarity of the detection scanning pulse applied to the scanning electrode is inverted every vertical scanning period. . 10. The liquid crystal display device with a coordinate detection function according to claim 7, wherein in the detection period, the polarity of the detection scanning pulse applied to the counter electrode is inverted every vertical scanning period. Drive circuit.