JP3085837B2 - Position detection 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 position detecting device for detecting a designated position on a flat plate.

[0002]

2. Description of the Related Art FIG. 6 shows a conventional position detecting device for detecting a pointed position on a flat plate. This position detecting device comprises a plurality of column electrodes X ₁ , X ₂ ,..., X _n which are insulated and arranged in parallel and a plurality of row electrodes Y ₁ , Y which are arranged in parallel and orthogonal to the column electrode group. A substrate 1 on which ₂ ,..., Y _m are formed, a column electrode driving unit 2 for applying a column electrode scanning signal to the column electrode X, and a row electrode driving unit 3 for applying a row electrode scanning signal to the row electrode Y. A detection pen 4 for detecting each scanning signal applied to the column electrode X or the row electrode Y;
And a control unit 8 that controls the operations of the column electrode driving unit 2 and the row electrode driving unit 3 for determining the tip coordinates of the detection pen 4 based on the detection signal output from the control unit 4.

The control unit 8 sends scanning signals x and y having pulse voltages having a predetermined time difference to the column electrode driving unit 2 and the row electrode driving unit 3 as shown in FIG. The electrode Y is scanned. At the same time, a control signal is sent to the column electrode drive unit 2, the row electrode drive unit 3, and the coordinate determination unit 5 to notify that the column electrode X or the row electrode Y is being scanned.

The above-mentioned column electrode driving section 2 and row electrode driving section 3
Has a gate inside. According to a signal from the control unit 8, the gate of the row electrode driving unit 3 is closed during the period of scanning the column electrode X, while the gate of the column electrode driving unit 2 is closed during the period of scanning the row electrode Y. It shuts off. In this manner, the pulse voltages that have passed through the gates of the column electrode driving section 2 and the row electrode driving section 3 are sequentially applied to the column electrodes X ₁ , X ₂ ,.
X _n and row electrodes Y _1, Y _2, ..., is applied to the Y _m column electrodes X
And the row electrodes Y are scanned.

[0005] On the other hand, the coordinate determination unit 5 uses an x-coordinate detection circuit 6 and a y-coordinate detection circuit 7 to detect a detection signal detected by electrostatic coupling between the detection pen 4 on the substrate 1 and the two electrodes X and Y. And the control signal from the control unit 8 to detect the tip coordinates of the detection pen 4.

Next, as a position detecting device to which the above-mentioned position detecting device is applied, there is a position detecting device as shown in FIG.
(JP-A-50-10088). This position detecting device includes a column electrode X and a row electrode Y, which are insulated from each other and arranged in parallel, delay circuits 11 and 12 including an inductance L and a capacitor C, and a column electrode X through the delay circuits 11 and 12. and another different frequencies f _x to be applied to the row electrodes Y, to determine transmitter F _x for generating a voltage signal f _y, and F _y, the coordinates of the tip of the detection pen 13 based on the detection signal from the detection pen 13 The coordinate determination unit 14 is roughly configured. Voltage signals having different phases are applied to the respective column electrodes X and the respective row electrodes Y by the delay circuits 11 and 12 according to their positions. Therefore, the phase of different frequencies f _x by the detection pen 13, f voltage signal _y is detected, this detection signal and transmitter F _x, F _y x coordinate determining section 14 the phase of the output signal of the
By comparing the coordinates with the coordinate detection circuit 15 and the y-coordinate detection circuit 16, the tip coordinates of the detection pen 13 can be detected.

There is also a position detecting device integrated with a display device. In the case of this position detection device, for example, a column electrode drive unit and a row electrode drive unit that output scanning signals x, y are provided to row electrodes and column electrodes in an active matrix display panel as a display device, and the above-described detection pen is used. By detecting the scanning signals x and y, it is possible to detect the coordinates of the tip of the detection pen.

[0008]

However, the conventional position detecting device has the following problems. That is, in each of the above-described position detection devices, as a basic configuration, a plurality of column electrodes and a plurality of row electrodes, an electrode driving circuit for applying and driving some scanning signal to each of the electrodes, and controlling the electrode driving circuit. Control circuit is required. Therefore, when performing more accurate position detection, a larger number of column electrodes and row electrodes are required, which complicates the electrode drive circuit and the control circuit. This is true even in the case of the position detecting device disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 50-10088.

Further, since a capacitively coupled detection pen is used as a detection pen for detecting the scanning signal applied to each of the electrodes, the detection accuracy of the scanning signal applied to the upper column electrode and the lower detection accuracy of the scanning signal applied to the upper column electrode are reduced. The detection accuracy differs from the scanning signal applied to the row electrode, and an error occurs in the detection position when the detection pen is tilted and brought into contact with the display screen.

SUMMARY OF THE INVENTION An object of the present invention is to provide a position detecting device capable of detecting the coordinates of the tip of a detection pen on a flat plate with high accuracy with a simple structure.

[0011]

In order to achieve the above object, the present invention is directed to a first pulse generator and a second pulse generator for generating a pulse signal having a constant cycle with a predetermined time difference shorter than the cycle. A generator and a conductive film, wherein each of the first pulse signal from the first pulse generator and the second pulse signal from the second pulse generator are applied to two different points adjacent to each other at four corners, and And pointing any one point on the conductive film to detect first and second pulse signals applied by the first pulse generator and the second pulse generator and propagated on the conductive film. A detection pen for outputting a detection signal, and detecting a propagation time from when the first and second pulse signals are applied to the conductive film to when the detection pen detects the first and second pulse signals based on the detection signal from the detection pen. This Based on the propagation time is characterized by comprising a coordinate determination means for determining the coordinates of the tip of the detection pen.

According to a second aspect of the present invention, in the position detecting device of the first aspect, the coordinate determining means includes a first pulse signal from the first pulse generator and a second pulse signal from the second pulse generator. The second pulse signal and the detection signal from the detection pen are taken in, and the phase of the first pulse signal and the phase of the detection signal are compared to generate a first position information signal representing a phase difference. A phase comparator that generates a second position information signal representing a phase difference by comparing the phase of the signal with the phase of the detection signal, and based on the first position information signal and the second position information signal from the phase comparator. It is characterized by including a coordinate determination unit that determines the coordinates of the tip of the detection pen on the conductive film.

According to a third aspect of the present invention, in the position detecting device according to the first or second aspect of the present invention, the detecting pen has a conductive detecting electrode at a front end thereof. Are configured to detect first and second pulse signals propagating through the conductive film when they come into contact with the conductive film.

According to a fourth aspect of the present invention, in the position detecting device according to the first or second aspect of the present invention, the detecting pen is electrostatically coupled to the conductive film and is caused by the voltage of the conductive film. This is characterized in that it is a capacitively-coupled pen having a detection electrode at the tip thereof at which an induced voltage is induced.

According to a fifth aspect of the present invention, in the position detecting device according to any one of the first to fourth aspects, the conductive film is formed integrally with a display panel of the display device. It is characterized by:

According to a sixth aspect of the present invention, in the position detection device of the fifth aspect, the display panel is an active matrix type liquid crystal display panel, and the conductive film is the active matrix type liquid crystal display. It is a counter electrode in the panel, and the detection pen is the capacitive coupling pen.

[0017]

According to the first aspect of the present invention, the first and second pulse generators cause the first and second pulse signals having a fixed period to be applied to two different points adjacent to each other at the four corners of the conductive film according to the above-mentioned period. It is applied with a short predetermined time difference. And
When an arbitrary point on the conductive film is indicated by the detection pen, first and second pulse signals propagating through the conductive film are detected by the detection pen, and a detection signal is output. Then, based on the detection signal output from the detection pen, the first and second coordinates are determined by the coordinate determination means.
The propagation time from when the pulse signal is applied to the conductive film to when it is detected by the detection pen is detected, and the tip coordinates of the detection pen are determined.

In the invention according to claim 2, when the coordinates of the tip of the detection pen are detected by the coordinate determination means, first, the phase of the first pulse signal and the phase of the detection signal are detected by a phase comparator. Are compared to generate a first position information signal representing a phase difference corresponding to the propagation time, and the phase of the second pulse signal is compared with the phase of the detection signal to produce a second position information signal representing the phase difference. An information signal is generated. Then, by the coordinate determination unit,
The tip coordinates of the detection pen on the conductive film are determined based on the first and second position information signals.

Further, in the invention according to claim 3, when the tip of the detection pen contacts the conductive film, the conductive detection electrode provided at the tip of the detection pen propagates the first conductive film through the conductive film. , A second pulse signal is detected. Thereafter, the tip coordinates of the detection pen are determined based on the detection signal detected by the detection pen.

According to the fourth aspect of the present invention, the first and second pulse signals propagated through the conductive film to a detection electrode provided at the tip of the detection pen and electrostatically coupled to the conductive film. An induced voltage is induced. Thereafter, the tip coordinates of the detection pen are determined based on the detection signal induced on the detection electrode of the detection pen.

In the invention according to claim 5, based on the coordinates of the tip of the detection pen determined by the coordinate determination means,
An image is displayed on the display panel by the display device, and the image is displayed at the position indicated by the detection pen.

Further, in the invention according to claim 6, the first and second pulse signals applied to and propagated to the opposite electrode in the active matrix type liquid crystal display panel are detected by the detection pen, The coordinates of the tip of the detection pen are determined by the coordinate determination means based on the detection signal. Then, based on the determined tip coordinates of the detection pen, an image is displayed at the position indicated by the detection pen on the liquid crystal display panel.

[0023]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a position detecting apparatus according to the present invention.

<First Embodiment> FIG. 1 is a diagram showing a position detecting device according to the present embodiment, and shows a basic configuration of a position detecting device according to the present invention. 1 includes a first pulse generator 21, a second pulse generator 22, a conductive film 23, a control unit 24, a detection pen 25, a first phase comparator 26, a second phase comparator 27, and coordinates. It is schematically composed of a decision unit 28.

The first pulse generator 21 and the second pulse generator 22 generate a pulse signal having a constant period and apply it to the conductive film 23 having a rectangular shape. At this time, the control section 24 controls the two pulse signals so as to be output with a certain fixed time difference (a time difference shorter than the cycle) t. The detection pen 25 detects the pulse signal applied to the conductive film 23 and sends out a detection signal to the first phase comparator 26 and the second phase comparator 27. Then, the first phase comparator 26 and the second phase comparator 27 detect the phase difference between the pulse signal from the first pulse generator 21 or the second pulse generator 22 and the detection signal from the detection pen 25. A first position information signal or a second position information signal is generated. The coordinate determining unit 28 determines the tip coordinates of the detection pen 25 based on the first position information signal and the second position information signal obtained by the first phase comparator 26 and the second phase comparator 27, and It outputs a signal.

The above will now be described in more detail.
The pulse signals output from the first pulse generator 21 and the second pulse generator 22 are applied to two different points (a) and (b) adjacent to each other at the four corners of the conductive film 23. Conductive film 2
Reference numeral 3 denotes a transmission system having a uniform resistance component, inductance component, and capacitance component.
The pulse signals applied to the conductive film 23 from the first and second pulse generators 22 (hereinafter, the pulse signal output from the first pulse generator 21 is referred to as a first pulse signal, and the pulse signal output from the second pulse generator 22 The pulse signal thus generated is referred to as a second pulse signal), which spreads uniformly over the entire surface of the film from the signal application points (a) and (b). At this time, the first,
The waveform of the second pulse signal has a phase difference and a rounding with respect to the original first and second pulse signals (FIGS. 2 (a) and (e)) as shown in FIGS. 3 (b) and 3 (f). It becomes a waveform. Then, the first pulse signal and the second pulse signal are output with a certain time difference t as shown in FIGS. 3 (a) and 3 (e).

In this manner, the first pulse signal and the second pulse signal propagating on the conductive film 23 are detected by the detection pen 25 having a detection electrode in contact with the conductive film 23 at the tip, and FIG. A detection signal having a waveform as shown in (f) is obtained. Then, the first phase comparator 26 operates as shown in FIG.
A first position information signal is obtained from the waveform of the first pulse signal shown in FIG. 3A and the waveform of the detection signal shown in FIG. On the other hand, the second phase comparator 27 obtains the second position information signal from the waveform of the second pulse signal shown in FIG. 3 (e) and the waveform of the detection signal shown in FIG. 3 (f).

Next, the first phase comparator 26 and the second
The position information signal generation performed by the phase comparator 27 will be described. The first and second phase comparators 26 and 27
FIG. 2 (however, FIG. 2 is represented by the first phase comparator 26)
As shown in (1), a Schmitt trigger circuit 29 and an AND circuit 30 are provided. Hereinafter, the operation of the circuit of the first phase comparator 26 will be described with reference to FIGS.

The first pulse signal having the pulse waveform as shown in FIG. 3A sent from the first pulse generator 21 to the first phase comparator 26 is applied to the input terminal of the AND circuit 30. . Further, the detection signal of the first pulse signal detected by the detection pen 25 has a phase difference and rounding as shown in FIG. 3B, and is applied to the input terminal of the Schmitt trigger circuit 29. Then, a pulse signal having a waveform as shown in FIG. 3C is output from the Schmitt trigger circuit 29 and applied to another input terminal of the AND circuit 30. Here, the pulse signal from the Schmitt trigger circuit 29 is more conductive film 2 than the original first pulse signal.
Distance between the first pulse signal application point (a) and the tip of the detection pen 25 (c) (distance (d) if the original pulse signal is the second pulse signal): first and second pulse signals (Proportional to the propagation time). Therefore, the AND circuit 30 obtains a first position information signal in which the phase difference between the first pulse signal from the first pulse generator 21 and the pulse signal from the Schmitt trigger circuit 29 is pulse width modulated.

When the time t has elapsed since the first pulse signal was output from the first pulse generator 21, the second pulse signal is output from the second pulse generator 22. And the second
The Schmitt trigger circuit and the AND circuit in the phase comparator 27 detect the second pulse signal having the waveform shown in FIG. 3E and the detection signal having the waveform shown in FIG. The second position information signal having the waveform shown in FIG.

The first and second position information signals obtained as described above are sent to a coordinate determination unit 28, which uses the maximum value of the phase delay by the conductive film 23 and each position information signal. The x and y coordinates of the tip of the detection pen 25 are determined from the ratio of the detection signal to the phase delay, and a coordinate signal is output.

As described above, in this embodiment, the first and second pulse generators 21 and 22 sequentially and repeatedly repeat the first and second pulse signals with a time difference t under the control of the control unit 24. The voltage is applied to two points (a) and (b) at the corners of the film 23. Then, the phase difference between the first and second pulse signals and the detection signal from the detection pen 25 is detected by the first and second phase comparators 26 and 27, and the tip position of the detection pen 25 on the conductive film 23 is detected. Are generated. Then, the coordinate deciding unit 28 makes the first and second phase comparators 26 and 2
7 based on the first and second position information signals from
5 is detected. Therefore,
The tip coordinates of the detection pen 5 can be detected with a very simple structure in which two pulses having a time difference t are sequentially and repeatedly applied to one conductive film 23 by the two pulse generators 21 and 22.

Therefore, according to the present embodiment, it is not necessary to arrange the column electrodes and the row electrodes in two layers on the position detecting surface. Further, there is no detection error due to a difference in distance between the column / row electrodes and the detection electrodes of the detection pen, and highly accurate position detection can be performed.

<Second Embodiment> This embodiment is a more specific embodiment in which the basic configuration shown in the first embodiment is combined with a display device. The position detecting device according to the present embodiment is a position detecting device capable of displaying an image based on the obtained coordinate detection signal on a display device, and has a configuration as shown in FIG.

First and second pulse generators 31 and 32, conductive film 33, control unit 34, detection pen 35, first and second phase comparator 3
6, 37, the coordinate determination unit 38 includes the first and second pulse generators 21 and 22, the conductive film 23, the control unit 24, and the detection pen 2 shown in FIG.
5. It has the same structure as the first and second phase comparators 26 and 27 and the coordinate determination unit 28, and operates as described in the first embodiment to detect the tip coordinates of the detection pen 35.

The conductive film 33 is formed transparent.
The display contents of the display panel 40 of the display device stacked below the conductive film 33 can be seen through the conductive film 33. The display control unit 39 includes a coordinate determination unit 38
The display device is controlled based on the x and y coordinate signals representing the coordinates of the tip of the detection pen 35 from the camera to display a point at the tip of the detection pen 35 on the display panel 40. as a result,
When the detection pen 35 slides on the conductive film 33, graphic input and graphic detection can be performed.

At this time, the conductive film 33 laminated on the display panel 40 is formed of one thin film. Therefore, the display device according to the present embodiment is
A conventional position detecting device having column electrodes and row electrodes arranged in layers can be formed thinner than a display device integrated with a display panel.

<Third Embodiment> This embodiment is an embodiment in which an active matrix type liquid crystal display device is used as the display device in the second embodiment. FIG. 5 is a schematic block diagram of the position detecting device of the present embodiment, which is incorporated in an active matrix type liquid crystal display device.

This display device is an active matrix type liquid crystal display panel (hereinafter simply referred to as a display panel) 4.
1 and a row electrode driving circuit 4 for driving the display panel 41
A display control circuit 44 that supplies a display control signal to the second and column electrode driving circuits 43; a coordinate detection circuit 46 that receives a detection signal from the detection pen 45 and detects the tip coordinates of the detection pen 45 on the display panel 41; It is schematically constituted by a first pulse generator 47 and a second pulse generator 48 for outputting a pulse signal at the time of detection, a coordinate detection circuit 46 and a control unit 49 for controlling the first and second pulse generators 47 and 48. You.

The display panel 41 has a plurality of row electrodes G1, G2, G3,..., G6 arranged in parallel on a transparent TFT (thin film transistor) substrate 50, and is arranged in parallel at right angles to the row electrode group. , S6. T is set at the intersection of each row electrode G and column electrode S.
An FT 51 is set, a row electrode G is connected to a gate electrode of each TFT 51, a column electrode S is connected to a source electrode, and a picture element electrode 52 is connected to a drain electrode.

On the back side of the TFT substrate 50, the TF
A counter substrate 53 is arranged to face the T substrate 50, and a counter electrode 54 having substantially the same area as the TFT substrate 50 is provided on the counter substrate 53. Then, a liquid crystal is sandwiched between the pixel electrode 52 and the counter electrode 54, and the pixel matrix is formed by the pixel electrodes 52 arranged in a matrix, the liquid crystal facing the pixel electrode 52, and the counter electrode 54. Make up.
A bias voltage is supplied to the counter electrode 54 by a power supply circuit 56 and a counter electrode drive circuit 55, and the first pulse generator 47 and the second pulse generator 4
Each of the first pulse signal and the second pulse signal output from 8 is repeatedly applied to two different points adjacent to each other at the four corners of the counter electrode 54 with a time difference t.

The detection pen 45 has a high input impedance and is coupled to the counter electrode 54 by a floating capacitance.
(Not shown) at the tip, and the counter electrode 5 is provided by the first pulse generator 47 and the second pulse generator 48.
4, an induced voltage is induced by the voltages of the first and second pulse signals that propagate through the counter electrode 54. The coordinate detection circuit 46 includes a first phase comparator 26, a second phase comparator 27, and a coordinate determination unit 28 in FIG. 1, and includes a first pulse generator 47 and a second pulse generator 48.
By detecting the phase difference between the first and second pulse signals from the detection pen 45 and the detection signal from the detection pen 45, the display panel 4
The x coordinate and the y coordinate of the tip of the detection pen 45 on 1 are detected. Note that the first and second pulse signals applied to the counter electrode 54 are signals of a voltage that does not affect the display by each picture element.

By inputting the coordinate signal detected by the coordinate detection circuit 46 as a part of the display data to the display control circuit 44, the row electrode drive circuit 42 and the column The row electrode G and the column electrode S are driven by the electrode drive circuit 43, and a point is displayed on the display panel 41 at the coordinates indicated by the detection pen 45. As a result, pen input becomes possible as the detection pen 45 slides on the display panel 41.

As described above, in this embodiment, since the conductive film is formed by the counter electrode 54 of the active matrix type display panel 41, the position detecting device is formed by using the active matrix type display panel as it is. it can. Therefore, according to this embodiment, it is possible to provide a position detecting device in which the conductive film is integrated with the display panel simply and at low cost.

The detection pens 25 and 35 in the first and second embodiments may be capacitive coupling pens having a detection electrode coupled to the conductive films 23 and 33 by floating capacitance at the tip thereof. The detection pen may have a conductive detection electrode at its tip for detecting the first and second pulse signals that come into contact with and propagate through the conductive members 23 and 33. In each of the above embodiments, the first and second phase comparators 26.3 are used.
6, 27 and 37, the phase difference between the first and second pulse signals and the detection signal is detected, whereby the conductive films 23 and 33 are detected.
Alternatively, the propagation times of the first and second pulse signals propagating through the counter electrode 54 are detected. However,
The present invention is not limited to this.

[0046]

As is apparent from the above description, the position detecting apparatus according to the first aspect of the present invention comprises a first pulse generator and a second pulse generator.
First and second pulse signals from a pulse generator are applied to two different points adjacent to each other at the four corners of the conductive film, and the first and second pulse signals propagating on the conductive film are detected by a detection pen, and the coordinates are detected. The determination means determines the tip coordinates of the detection pen based on the propagation times of the first and second pulse signals. Therefore, one conductive film covering the sliding range of the detection pen and the first and second pulses are determined. The coordinates of the tip of the detection pen on the flat plate can be detected by a simple device such as a generator and a detection pen. Therefore, it is not necessary to arrange the row electrodes and the column electrodes in two layers on the position detection surface as in the conventional position detection device, and the detection accuracy is limited by the arrangement pitch of the column electrodes and the row electrodes, and the row / column electrodes and the detection pen There is no detection error due to the difference in distance between the two, and more accurate coordinate detection can be performed.

According to a second aspect of the present invention, in the position detecting device, the coordinate determining means includes a phase comparator and a coordinate determining unit, and the phase comparator compares the phases of the first and second pulse signals with each other. By detecting the difference between the phase of the detection signal from the detection pen and the first and second position information signals representing the propagation time, the coordinate determination unit generates the first and second position information signals based on the first and second position information signals. Thus, the coordinates of the tip of the detection pen are determined, so that the coordinates determination means can be easily configured.

In the position detecting device according to the third aspect of the present invention, when the conductive detection electrode provided at the tip of the detection pen comes into contact with the conductive film, the first and the second propagate the conductive film. Since the pulse signal is detected, the first and second pulses can be reliably detected. Therefore, the tip coordinates of the detection pen can be detected with higher accuracy.

According to a fourth aspect of the present invention, there is provided the position detecting device according to the first and second aspects of the present invention, wherein the first and second detection electrodes are provided at the tip of the detection pen and propagate through the conductive film by the detection electrodes electrostatically coupled to the conductive film.
Since the first and second pulse signals propagating through the conductive film are detected by detecting an induced voltage caused by the pulse signal, the detection pen does not directly contact the conductive film, so that the detection pen does not contact the first and second pulse signals. A signal can be detected and a detection signal can be output. In this case, since the conductive film electrostatically coupled to the detection electrode of the detection pen is formed as a single sheet, the detection accuracy of the x coordinate and the detection accuracy of the y coordinate become the same, and The tip coordinates can be detected with high accuracy.

Further, in the position detecting device according to the present invention, since the conductive film is formed integrally with the display panel of the display device, the conductive film is formed based on the coordinates of the tip of the detecting pen determined by the coordinate determining means. An image can be displayed at the position indicated by the detection pen. Therefore, pen input by the detection pen becomes possible as if writing on paper with a writing instrument.

Further, in the position detecting device according to the present invention, since the conductive film is constituted by a counter electrode of an active matrix type liquid crystal display panel, position detection is performed using the active matrix type liquid crystal display panel as it is. The device can be formed. Therefore, according to the present invention, it is possible to provide a position detecting device in which the conductive film is integrated with the display panel simply and at low cost.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a basic configuration of a position detecting device according to the present invention.

FIG. 2 is a specific circuit diagram of a first phase comparator in the position detection device shown in FIG.

FIG. 3 is a signal waveform diagram of each part in the position detection device shown in FIG.

FIG. 4 is a block diagram of a position detecting device different from FIG.

FIG. 5 is a block diagram of a position detecting device different from FIG. 4;

FIG. 6 is a block diagram of a conventional position detecting device.

7 is a timing chart of a column electrode scanning signal and a row electrode scanning signal in the position detection device shown in FIG.

FIG. 8 is a block diagram of a conventional position detecting device different from FIG.

[Explanation of symbols]

21, 31, 47 ... first pulse generator, 22, 32, 48 ...
2nd pulse generator, 23, 33 ... conductive film,
24, 34, 49 ... control unit, 25, 35, 45 ... detection pen, 26, 36 ... first phase comparator, 27, 37 ...
Second phase comparator, 28, 38... Coordinate determination unit, 29
... Schmitt trigger circuit, 30 ... And circuit, 3
9: display control unit, 40, 41: display panel, 46: coordinate detection circuit, 51: TF
T, 54: Counter electrode.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-314165 (JP, A) JP-A-64-10319 (JP, A) JP-A-2-55323 (JP, U) (58) Field (Int.Cl. ⁷ , DB name) G06F 3/03 320 G06F 3/033 350

Claims (6)

(57) [Claims] A first pulse generator for generating a pulse signal having a predetermined period with a predetermined time difference shorter than the period;
And a pulse generator, wherein each of the first pulse signal from the first pulse generator and the second pulse signal from the second pulse generator are applied to two different points adjacent to each other at four corners. A film and an arbitrary point on the conductive film are designated to detect first and second pulse signals applied by the first pulse generator and the second pulse generator and propagated on the conductive film. And a propagation time from when the first and second pulse signals are applied to the conductive film to when they are detected by the detection pen based on the detection signal from the detection pen. A position detecting device comprising: a coordinate determining means for detecting and determining the tip coordinates of the detection pen based on the propagation time. 2. The position detecting device according to claim 1, wherein said coordinate determining means comprises: a first pulse signal from a first pulse generator, a second pulse signal from a second pulse generator, and the detection pen. And generating a first position information signal representing a phase difference by comparing the phase of the first pulse signal with the phase of the detection signal, and determining the phase of the second pulse signal and the phase of the detection signal. A phase comparator that generates a second position information signal representing a phase difference by comparing the first position information signal and the second position information signal from the phase comparator; A position detection device comprising a coordinate determination unit that determines coordinates of a tip. 3. The position detection device according to claim 1, wherein the detection pen has a conductive detection electrode at a tip thereof,
A position detecting device for detecting first and second pulse signals propagating through the conductive film when the tip contacts the conductive film. 4. The position detecting device according to claim 1, wherein the detection pen is electrostatically coupled to the conductive film and an induced voltage is induced due to a voltage of the conductive film. A position detecting device comprising a capacitive coupling pen having an electrode at a tip portion thereof. 5. The position detecting device according to claim 1, wherein the conductive film is formed integrally with a display panel of the display device. . 6. The position detecting device according to claim 5, wherein the display panel is an active matrix type liquid crystal display panel, the conductive film is a counter electrode in the active matrix type liquid crystal display panel, The position detecting device, wherein the detecting pen is the capacitive coupling pen.