JPH0643992A - Touch panel and touch panel device - Google Patents

Abstract

PURPOSE: To always detect a precise depression position without the trouble of calibration. CONSTITUTION: The touch panel 11 has a sheet resistance member 12, voltage applying electrodes 13-16 provided for the four sides of the sheet resistance member 12 and reference potential detection electrodes 17 and 18 provided for the opposite angle parts of a depression position detection area 12 in the sheet resistance member 12. A control circuit 31 has a power source for voltage application 32, switches 33a-33d and an A/D converter 34 where the reference potential detection electrodes 17 and 18 are connected to the input terminal 34b (Vref-) of a minus-side reference potential and the input terminal 34a (Vref+) of a plus-side reference potential and a stylus pen 35 is connected to the input terminal 34c (Vin) of depression position detection potential.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a touch panel used as an input device in a computer system or the like, and a touch panel device for detecting a position where a finger or a pen-shaped member contacts.

[0002]

2. Description of the Related Art Conventionally, there is known a touch panel device in which a planar resistance member has a predetermined potential gradient and the contact position is detected by the potential at the position where a stylus pen or the like contacts. More specifically, for example, as shown in FIG. 6, this type of touch panel device is provided with electrodes 2 and 3 on opposite sides of a square planar resistance member 1, and applies a predetermined voltage to the electrodes 2 and 3. When the planar resistance member 1 is pressed with the stylus pen 4 in the applied state, a potential difference is generated between the electrode 2 and the stylus pen 4 according to the pressing position.

In this type of touch panel device, the electrodes 2
It is not possible to accurately detect the pressed position due to the accuracy of the power supply that applies a voltage to the sensor 3, the accuracy of the potential detection circuit that detects the potential of the stylus pen 4, and the variation in the sheet resistance of the sheet resistance member 1. is there. Therefore, in the conventional touch panel device, a stabilized power source is used as a power source for applying a voltage to the electrodes 2 and 3 and a power source for applying a reference voltage to the A / D converter of the potential detection circuit, and the output voltage of these power sources is used. By precisely calibrating, the detection accuracy of the pressed position has been increased.

[0004]

However, in the above-mentioned conventional touch panel device, it is necessary to perform a precise calibration for each device at the time of manufacturing, and the calibration is performed each time when there is a change over time. It is necessary and time-consuming.

Instead of directly adjusting an electric circuit or the like, a D / A converter controlled by software is used to press a predetermined area of the sheet resistance member 1 to interactively perform calibration. Although a touch panel device capable of performing the above is also known, even in this case, the labor required for calibration cannot be eliminated.

In view of the above points, an object of the present invention is to provide a touch panel device which can always perform accurate detection of a pressed position without requiring labor for calibration.

[0007]

In order to achieve the above object, a touch panel according to a first aspect of the present invention has a resistance member to which a voltage is applied and a potential gradient is formed in a predetermined direction; It is characterized in that a contact electrode electrically contacting a position corresponding to the pressing and a fixed electrode electrically connected to a predetermined position of the pressing region of the resistance member are provided.

According to another aspect of the touch panel device of the present invention, a fixed electrode is provided at both ends of the pressing area of the resistance member in the direction of the potential gradient, and a voltage between the fixed electrode and either one of the two. And a pressing position detecting means for detecting the pressing position based on the ratio of the voltage between the fixed electrode and the contact electrode. Claim 3
The touch panel device according to claim 1, wherein the fixed electrodes are provided at both ends of the pressing region of the resistance member in the potential gradient direction, and based on the voltage between the fixed electrodes,
Voltage control means for controlling the voltage applied to the resistance member.

[0009]

In the touch panel according to the first aspect, the relative relationship between the potential of the fixed electrode and the potential of the contact electrode depends only on the pressing position regardless of fluctuations in the voltage applied to the resistance member. Further, it is possible to constantly monitor the fluctuation of the voltage applied to the resistance member and the like by the potential of the fixed electrode.

In the touch panel device according to claim 2,
The pressed position detection means detects the pressed position based on the ratio of the voltage between the two fixed electrodes and the voltage between any one of the fixed electrodes and the contact electrode. In the touch panel device according to the third aspect, the voltage control unit controls the voltage applied to the resistance member based on the voltage between the two fixed electrodes.

[0011]

【Example】

(First Embodiment) A first embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a configuration diagram showing a configuration of a touch panel device including a touch panel 11 and a control circuit 31.

As shown in FIG.
The sheet resistance member 12, the voltage application electrodes 13 to 16 provided on the four sides of the sheet resistance member 12, and the pressed position detection area 12a (the area indicated by a chain double-dashed line in the figure) in the sheet resistance member 12 are shown. Reference potential detection electrodes 17 and 18 provided at diagonal portions
It consists of and. Here, the pressed position detection area 12a may be an area defined by a casing (not shown) of the touch panel 11 or a virtual area.

The sheet-like resistance member 12 is made of a material having a uniform resistance value per unit length and unit width (hereinafter referred to as sheet resistance) over the entire surface.
The one manufactured by ly of Holland is used. More specifically, for example, a thick-film resistive coating made of a semiconductor metal oxide such as indium-tin oxide, tin oxide, tin-antimony oxide, or indium oxide on a substrate made of plastic or glass, or sputtering. Alternatively, a thin film resistor such as a vapor deposition film is formed.

The surface resistance of these materials is, for example, 200 to
Selected to be 500Ω. Further, when the sheet resistance member 12 is used by being mounted on the front surface of the CRT, it is necessary to select a transparent one, but when it is used for a digitizer or the like, an opaque member may be selected. The voltage applying electrodes 13 to 16 are respectively connected to voltage applying wirings 21 to 24 at their ends and have a predetermined resistance value in the longitudinal direction, so that a voltage is applied between the voltage applying electrodes 13 and 14, for example. In this case, the current leaking through the voltage applying electrodes 15 and 16 is suppressed to be small.

The control circuit 31 includes a voltage applying power source 32,
Switches 33a to 33d and an A / D converter 34 are provided and configured. The switches 33a to 33
By connecting d as shown in the figure, when the switches 33a and 33b are turned on, a potential gradient in the X-axis direction is formed on the planar resistance member 12, while the switches 33c and 33d are turned on. When turned on, a potential gradient in the Y-axis direction is formed. Here, when each of the voltage applying electrodes 13 to 16 is formed in a linear shape as described above, the equipotential lines are not strictly linear in the peripheral portion of the planar resistance member 12, but this is prevented. For this purpose, a buffer region may be provided in the peripheral portion of the sheet resistance member 12, or each of the voltage applying electrodes 13 to 16 may be formed in a parabolic shape.

In the A / D converter 34, the reference potential detection electrodes 17 and 18 are connected to the negative reference potential input terminal 34b (Vref-) and the positive reference potential input terminal 34a (Vref +), respectively. The stylus pen 35 is connected to the input terminal 34c (Vin) of the pressed position detection potential. This A / D
If the converter 34 performs A / D conversion based on two reference potentials of the highest potential and the lowest potential,
Various types such as a successive approximation type and a parallel comparison type are applicable.

In place of the stylus pen 35,
A planar electrode, a resistive film, or the like which is flexible and is provided at a predetermined distance from the planar resistance member 12 may be used. Also,
Reference potential detection electrodes 17 and 18 and stylus pen 35
Since almost no current flows in the wiring connecting the A / D converter 34 and the A / D converter 34, a wiring having a smaller wire diameter than the wirings 21 to 24 can be used.

In the above configuration, the A / D converter 3
4 uses the potentials of the reference potential detection electrodes 17 and 18 as reference potentials to A / D-convert the potential of the stylus pen 35. Therefore, when the outer edge of the pressed position detection area 12a is pressed, the minimum value or The maximum digital signal is A /
It is output from the D converter 34. Further, even if the output voltage of the voltage applying power supply 32 changes, the potential input to the input terminals 34a and 34b also changes as the potential input from the stylus pen 35 to the input terminal 34c of the A / D converter 34 changes. Since the proportional relationship between the two is always constant, an accurate pressed position can be detected. That is, it is not necessary to precisely adjust the output voltage of the voltage applying power supply 32, and it is not necessary to highly smooth the output voltage. Further, even when in-phase noise is superimposed on the input terminals 34a to 34c, the pressed position can be accurately detected in the same manner.

Therefore, the error due to the accuracy of the output voltage of the voltage applying power supply 32, the noise, etc. is automatically compensated without using high-precision and expensive parts or requiring the trouble of calibration. , Accurate detection result can be obtained. In the above example, the example in which only the pressing position is detected is shown, but the presence or absence of the pressing operation may also be detected. This is because, for example, a voltage sufficiently higher than that of the reference potential detection electrode 18 is periodically applied to A /
While giving to the input terminal 34a of the D converter 34,
This can be realized by applying the above voltage to the input terminal 34c via a predetermined resistance. As a result, when the presence or absence of the pressing is detected, the high voltage is detected if the stylus pen 35 is not in contact with the planar resistance member 12, and if the contact is made, the potential of the reference potential detection electrode 18 or lower is high at the highest. Since it is detected, it is possible to detect the presence or absence of pressing. When the pressed state is detected, the voltage may be disconnected and the pressed position may be detected. (Second Embodiment) A second embodiment of the present invention will be described below with reference to FIG.

The touch panel device of the second embodiment is constructed by connecting the control circuit 41 to the same touch panel 11 as in the first embodiment. In the second embodiment, the components having the same functions as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. Control circuit 4
1 has input terminals 42a to 44a of the positive reference potential.
For example, three A / D converters 42 to 44 to which the same reference potential higher than the potential of the voltage application power supply 32 is applied to (Vref +) are provided. Input terminals 42b to 44b (Vi for inputting detection potential of each A / D converter 42 to 44)
The reference potential detection electrode 18, the stylus pen 35, or the reference potential detection electrode 17 is connected to each of n). As the A / D converters 42 to 44, those that detect an absolute potential, such as an integral A / D converter, or those that detect a relative potential may be used. When the balanced input A / D converter is used, the potential difference between the reference potential detection electrodes 17 and 18 and the reference potential detection electrode 1 are directly adjusted by the two A / D converters.
7. The potential difference between the stylus pen 35 may be detected.

The digital values output from the A / D converters 42 to 44 are input to the arithmetic unit 45, respectively. In the above configuration, A / D
The converters 42 to 44 respectively use the reference potential detection electrode 18, the stylus pen 35, and the stylus pen 35 based on the same reference potential.
Alternatively, the potential of the reference potential detection electrode 17 is A / D converted.
Therefore, by calculating the ratio of the difference between the digital values output from the A / D converters 42 and 44 and the difference between the digital values output from the A / D converters 43 and 44 by the arithmetic unit 45, the first embodiment The exact pressing position is detected by the same principle as the example.

Note that one A / D converter may be switched and used without providing the three A / D converters 42 to 44 as described above. In this case, it is not effective in removing common-mode noise having a short cycle, but it has a relatively long cycle due to fluctuations in power supply voltage due to environmental changes such as temperature and humidity and changes in resistance characteristics of the sheet resistance member 12. It is possible to fully compensate for the factors.

The detection of the potentials of the reference potential detection electrodes 17 and 18 is not limited to the constant detection, but may be performed periodically such as at the time of starting. Further, the digital value output from the A / D converters 42 and 44 is input to the arithmetic unit 45, and the value output according to this is converted into a voltage by the D / A converter, and the A / D converter of the first embodiment is used. It may be applied as a reference voltage in the / D converter 34. In this case, it is possible to easily multiply the reference voltage of the A / D converter 34 by a predetermined value or give a predetermined offset by subjecting the digital value to a predetermined conversion by the arithmetic unit 45. (Third Embodiment) A third embodiment of the present invention will be described below with reference to FIG.

The touch panel device according to the third embodiment has the first
A control circuit 51 is connected to the same touch panel 11 as that of the embodiment. Also in the third embodiment, the components having the same functions as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted. Control circuit 5
1, a D / A converter 52 that generates a voltage according to a digital value output from the arithmetic unit 45 is provided in place of the voltage applying power supply 32 in the control circuit 41 of the second embodiment.

The arithmetic unit 45 also increases or decreases the digital value output to the D / A converter 52 so that the difference between the digital values output from the A / D converters 42 and 44 becomes constant. . With this configuration, a feedback loop is formed by the A / D converters 42 and 44, the arithmetic unit 45, and the D / A converter 52, and the reference potential detection electrode 17.1.
Since the voltage between 8 is always kept constant, the A / D converter 43 outputs a value corresponding to the accurate pressing position.

Further, another D / A converter is provided, and according to the value output from the A / D converter 44,
The offset of the potential of the reference potential detection electrode 17 (potential difference with respect to the ground potential) may also be controlled. (Fourth Embodiment) A fourth embodiment of the present invention will be described below with reference to FIG.

The touch panel device of the fourth embodiment has the first
A control circuit 61 is connected to the same touch panel 11 as that of the embodiment. Note that, also in the fourth embodiment, the components having the same functions as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. Control circuit 6
1 includes an arithmetic unit 4 in addition to the control circuit 41 of the second embodiment.
An amplifier 62 whose gain and offset are variable in accordance with the value output from 5 is provided.

In the arithmetic unit 45, the amplifier 62 is
The offset is controlled according to the value output from the A / D converter 44, and the gain is controlled according to the value inversely proportional to the difference between the values output from the A / D converters 42 and 44. With the above configuration, the potential of the reference potential detection electrode 17 and the reference potential detection electrode 17.1.
Since the influence of the fluctuation in the potential difference between 8 is canceled by the amplifier 62, the potential corresponding to the pressing position is always input to the A / D converter 43, and the accurate pressing position is detected. (Fifth Embodiment) A fifth embodiment of the present invention will be described below with reference to FIG. In addition, also in the fifth embodiment, the first
Constituent parts having the same functions as those in the embodiment are designated by the same reference numerals and the description thereof will be omitted.

The touch panel 70 in the touch panel device of the fifth embodiment has flexibility or elasticity.
The sheet-shaped resistance films 71 and 81 are provided so as to be spaced apart from each other by a predetermined distance, and are configured to come into contact with each other at the pressed position when pressed. The resistance films 71 and 81 are
Electrodes 72, 73, 82, and 83 are provided on both edges, respectively. Further, reference potential detection electrodes 74, 75, 84, and 85 are provided at the diagonal portions of the pressed position detection regions 71a and 81a in the resistance films 71 and 81, respectively.

The control circuit 91 includes a voltage applying power source 32,
The A / D converter 34 and the switches 92 to 96 are provided and configured. The power supply 32 for voltage application uses the electrodes 72, 81 of the resistance films 71, 81 via the switches 92, 93.
73 or the electrodes 82 and 83 are selectively connected, and potential gradients in the X-axis direction and the Y-axis direction are alternately formed on the resistance films 71 and 81.

The input terminal 34a of the A / D converter 34
34b is a reference potential detection electrode 75/74 or a reference potential detection electrode 85 via the switches 94/95, respectively.
・ It is designed to be selectively connected to 84. Also,
The input terminal 34c is selectively connected to the electrode 82 or the electrode 72 via the switch 96.

In the above structure, the switches 92 to 96 are provided.
Is switched as shown in the figure, the resistance film 71
A potential gradient in the X-axis direction is formed on the resistance film 8 and
1 acts as a pressing position detecting electrode, and when the pressing operation makes contact with the resistance film 71, the potential of the resistance film 71 at that position is input to the input terminal 34c of the A / D converter 34 via the switch 96.

At this time, the potentials of the reference potential detection electrodes 75 and 74 are applied to the input terminals 34a and 34b of the A / D converter 34 through the switches 94 and 95, so that the first
Similar to the embodiment, the accurate pressing position is detected without being affected by the fluctuation of the output voltage of the voltage applying power supply 32 and the influence of the in-phase noise. On the other hand, when the switches 92 to 96 are switched to the opposite side of the drawing, the resistance films 71 and 81 have mutually opposite effects, and similarly the pressing position in the Y-axis direction is detected.

In each of the above embodiments, the example of the touch panel device for detecting the pressed position in the two-dimensional direction is shown, but the present invention is not limited to this, and may be applied to a touch panel device for detecting the pressed position in the one-dimensional direction. Good. Further, the reference potential detection electrode is not limited to the two provided as described above, and may be one, for example, when only the gain is corrected.
~ In the configuration like the fourth embodiment, three or more are provided,
It is also possible to perform multipoint sampling and perform processing such as weighted averaging to further improve the detection accuracy or to compensate for the linearity between the pressed position and the detected potential.

[0035]

As described above, according to the present invention,
By providing the fixed electrode electrically connected to the predetermined position of the pressing area of the resistance member, the relative relationship between the potential of the fixed electrode and the potential of the contact electrode is changed by the fluctuation of the voltage applied to the resistance member. Regardless of the above, only the pressing position is dealt with, so by detecting the pressing position based on the above relative relationship, it is possible to always perform accurate detection of the pressing position without the need for calibration. Has the effect.

Further, since the variation of the voltage applied to the resistance member can be constantly monitored by the potential of the fixed electrode and the voltage applied to the resistance member can be controlled based on this, the calibration is also performed. The present invention has an effect that the pressed position can be detected accurately at all times without the trouble of.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a configuration of a touch panel device according to a first embodiment.

FIG. 2 is a configuration diagram showing a configuration of a main part of a touch panel device according to a second embodiment.

FIG. 3 is a configuration diagram showing a configuration of a main part of a touch panel device according to a third embodiment.

FIG. 4 is a configuration diagram showing a configuration of a main part of a touch panel device according to a fourth embodiment.

FIG. 5 is a configuration diagram showing a configuration of a touch panel device in a fifth embodiment.

FIG. 6 is a configuration diagram showing a configuration of a conventional touch panel device.

[Explanation of symbols]

 11 Touch Panel 12 Sheet Resistance Member 12a Pressed Position Detection Area 13-16 Voltage Application Electrodes 17/18 Reference Potential Detection Electrodes 21-24 Wiring 31 Control Circuit 32 Voltage Application Power Supply 33a-33d Switch 34 A / D Converters 34a-34c Input Terminal 35 Stylus pen 41 Control circuit 42-44 A / D converter 42a-44a Input terminal 42b-44b Input terminal 45 Arithmetic device 51 Control circuit 52 D / A converter 61 Control circuit 62 Amplifier 70 Touch panel 71.81 Resistive film 71a.81a Pressed position detection area 72/73/82/83 electrode 74/75/84/85 Reference potential detection electrode 91 Control circuit 92 to 96 switch

Front Page Continuation (72) Inventor Andrew Wolf, 5524 Bebe Caves Road, Austin, Texas, USA United States, Graphics Graphics Technology Company (72) Inventor Gary Barrett Austin, Texas, USA , Bee Caves Road 5524 Inside The Graphics Technology Company

Claims (3)

[Claims] 1. A resistance member to which a voltage is applied to form a potential gradient in a predetermined direction, a contact electrode electrically contacting a position corresponding to the pressing of the resistance member by a pressing operation, and a pressing force on the resistance member. A touch panel, comprising: a fixed electrode electrically connected to a predetermined position of the area. 2. The touch panel according to claim 1, wherein the fixed electrodes are provided at both end portions in the potential gradient direction in the pressing region of the resistance member, the voltage between the fixed electrodes, and one of the fixed electrode and the contact electrode. A touch panel device, comprising: a pressed position detection unit that detects a pressed position based on a ratio with a voltage between the two. 3. The touch panel according to claim 1, wherein the fixed electrode is provided at both ends of the resistance member in the potential gradient direction in the pressing region, and the voltage applied to the resistance member is determined based on the voltage between the fixed electrode. A touch panel device comprising: a voltage control unit for controlling.