JP2004295281A - Abnormal input detection device for analog resistance film type touch panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To decide whether coordinates recognized on a touch panel are obtained by normal input operation or abnormal input operation. <P>SOLUTION: This detection device comprises: the analog resistance film type touch panel TP comprising two resistance films; respective electrodes X1, X2, Y1, Y2 in directions X, Y of the touch panel; electronic switches SWx1, SWx2, SWy1, SWy2 for alternately applying a reference voltage Vc to the respective electrodes in the directions X, Y; and voltage detection circuits VDCx1, VDCx2, VDCy1, VDCy2 detecting voltage between the electronic switches and a touch point to detect a position of the touch panel. The detection device has current detection circuits CDCx, CDCy for measuring current values flowing through the two resistance films, and deciding that abnormal input such as touch in two or more touch points on the touch panel, or the like, is executed when the measured value becomes a prescribed value or above. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a device for detecting an abnormal input of an analog resistive touch panel, and in particular, measures a current value flowing through two resistive films constituting the analog resistive touch panel, and when the current value exceeds a specified value. TECHNICAL FIELD The present invention relates to an abnormal input detection device for an analog resistive touch panel that can determine that an abnormal input has been made by touching at two or more touch points or a surface on a touch panel.
[0002]
[Prior art]
Conventionally, as this kind of analog resistive film type touch panel, those having configurations as shown in FIGS. 4A, 4B and 5 are known.
[0003]
In this 4-wire analog resistive touch panel, two films TPx and TPy having uniform resistance distribution are stuck together at a minute interval and touched, so that the two resistive films TPx and TPy contact at a touch point 100. A 4-wire analog resistive touch panel TP ', electrodes X1, X2 and electrodes Y1, Y2 provided to face the touch panel TP' in the X and Y directions, respectively, a transistor or a FET (Field-Effect Transistor), etc. And electronic switches SWx10, SWx20, SWy10, and SWy20 that alternately apply the reference voltage Vc to the electrodes X1, X2, Y1, and Y2 in the X and Y directions, and electronic switches SWx10, SWx20, SWy10, and SWy20. And touch point 100 It comprises voltage detection circuits VDCx10, VDCx20, VDCy10, VDCy20 for detecting the voltage between them and detecting the position of the touch panel TP '. The electrodes X1 and Y1 are connected to a power supply Vc serving as a reference voltage via electronic switches SWx10 and SWy10, respectively, and the electrodes X2 and Y2 are connected to circuit ground GND via electronic switches SWx20 and SWy20, respectively. .
[0004]
The position detection circuit configured as described above, when the two resistive films TPx and TPy adhered at a minute interval are touched (pushed) to make contact at the touch point 100, the resistance between the electrodes X1 and X2. The value is divided into Rx1 and Rx2 based on the touch point 100, and the resistance between the electrodes Y1 and Y2 is divided into Ry1 and Ry2.
[0005]
At this time, the resistance ratio is equal to the physical position (length) ratio as described below.
[0006]
Lx1: Lx = Rx2: (Rx1 + Rx2) (11)
Ly1: Ly = Ry2: (Ry1 + Ry2) (12)
Here, Lx and Ly are the X and Y dimensions of the effective area EA of the touch panel TP ', respectively, and Lx1 and Ly1 are the X and Y dimensions from the end of the effective area EA to the touch point 100, respectively. It is.
[0007]
Next, the operating principle of an ideal touch panel will be briefly described based on FIGS. 5, 6A and 6B.
[0008]
Now, when the electronic switches SWx10 and SWx20 in FIG. 5 are turned on and the electronic switches SWy10 and SWy20 are turned off, the power supply Vc is applied to the electrode X1 and the circuit ground GND is applied to the electrode X2 as shown in FIG. The voltage detection circuits VDCx10 and VDCx20 are connected to the electrodes Y1 and Y2. Therefore, a current flows from the power supply Vc to the circuit ground GND via the electrode X1, the resistance values Rx1 and Rx2 divided at the touch point 100, and the electrode X2. That is, the voltage detection circuits VDCx10 and VDCx20 can detect the next voltage values Vx1 and Vx2 divided by the resistance values Rx1 and Rx2.
[0009]
Vx1 = Vx2 = Vc × Rx2 / (Rx1 + Rx2) (13)
As described above, since the resistance value ratio is equal to the physical length ratio, the X-direction position Lx1 of the touch point 100 can be calculated using the voltage value Vx1 according to Expressions (11) and (13). Can be described as follows.
[0010]
Lx1 = Lx × Vx1 / Vc (14)
Similarly, at the next time, when the electronic switches SWy10 and SWy20 are turned on and the electronic switches SWx10 and SWx20 are turned off as shown in FIG. 6B, current flows in the direction of the electrodes Y1 and Y2, and the voltage detection circuit In VDCy10 and VDCy20, the next voltage values Vy1 and Vy2 divided by the resistance values Ry1 and Ry2 can be detected.
[0011]
Vy1 = Vy2 = Vc × Ry2 / (Ry1 + Ry2) (15)
Therefore, from Expressions (12) and (15), the position Ly1 in the Y direction of the touch point 100 can be described as follows using the voltage value Vy1.
[0012]
Ly1 = Ly × Vy1 / Vc (16)
Therefore, in the case of an ideal touch panel as described above, the coordinates of the touch point 100 are calculated from the voltage values Vx1 and Vy1 by using equations (14) and (16) by repeatedly changing the above two states. (Lx1, Ly1) can be calculated and recognized.
[0013]
[Patent Document 1] Japanese Patent Application Laid-Open No. 2002-278690 (pages 2 to 4; FIGS. 1 to 4).
[0014]
[Problems to be solved by the invention]
In such a conventional analog resistive touch panel, if two points on the touch panel TP 'are touched (pressed) at the same time, the resistance value between the electrodes X1 and X2 of the resistive film TPx at this time is shown in FIG. As shown in FIG. 7A, the image is divided into Rx3, Rx4, and Rx5 with the touch points 100A and 100B as base points. Further, the resistance value Ryp on the other resistive film TPy is connected in parallel with the previous Rx4. That is, at this time, at the DC voltage measurement ports Vx1 and Vx2, the voltage at approximately the middle point of the resistance value Ry4 is measured. The same can be said for measuring the voltage in the Y direction.
[0015]
Therefore, when two points on the touch panel TP 'are touched (pressed) at the same time, as shown in FIG. 7B, it is erroneously assumed that the approximate middle point MP of the actual touch points 100A and 100B is touched. There were difficulties to recognize. In other words, even if two or more points on the touch panel are touched or touched on the surface, even if the coordinates are erroneously recognized at the time of an abnormal input operation, are they the coordinates recognized by the correct input, Alternatively, since it is impossible to determine even the coordinates recognized by an erroneous input, in a touch panel system or the like linked with operation button display on a display device such as an LCD (Liquid Crystal Display), an unintended operation button is erroneously pressed. There was a risk of incorrect operation.
[0016]
The present invention has been made to solve such a conventional difficulty, and detects an abnormal input of an analog resistive touch panel that can determine whether the recognized coordinates are due to a normal input operation or an abnormal input operation. It is intended to provide a device.
[0017]
[Means for Solving the Problems]
The abnormal input detection device for an analog resistive touch panel according to the present invention, which achieves the above object, comprises two resistive films that are uniformly distributed in resistance, are attached at a very small interval, and are touched by a touch point. Analog resistive touch panel, X- and Y-direction electrodes of the touch panel, an electronic switch that alternately applies a reference voltage to each of the X- and Y-direction electrodes, and a switch between the electronic switch and the touch point. A voltage detection circuit that detects a voltage to detect the position of the touch panel, measures a current value flowing through the two resistive films, and, when the measured value is equal to or greater than a specified value, displays a signal on the touch panel. A current detection circuit for judging that an abnormal input has been made when two or more touch points are touched or a surface is touched.
[0018]
According to such an abnormal input detection device for an analog resistive touch panel, when an abnormal input operation is performed by touching at two or more touch points or a surface on the touch panel, the two sheets constituting the analog resistive touch panel Since the value of the current flowing through the resistive film increases, it is possible to determine whether the input is due to a normal input operation or an abnormal input operation by measuring the current value with a current detection circuit.
[0019]
Embodiment of the present invention
Hereinafter, a preferred embodiment of the analog resistive touch panel abnormal input detection device according to the present invention will be described with reference to the drawings.
[0020]
As shown in FIG. 1, the abnormal input detecting device for an analog resistive touch panel according to the present invention is configured such that two films TPx and TPy (FIG. 4) having a uniform resistance distribution are stuck and touched at a minute interval. A four-wire analog resistive touch panel TP in which two resistive films TPx and TPy contact each other at a touch point 50, and electrodes X1 and X2 and electrodes provided to face the touch panel TP in the X and Y directions, respectively. Y1 and Y2, and electronic switches SWx1, SWx2, SWy1, and SWy2 that are configured by transistors or FETs and that alternately apply the reference voltage Vc to the electrodes X1, X2, Y1, and Y2 in the X and Y directions. Voltage detection circuits VDCx1, VD that detect the voltage between touch points 50 to detect the position of touch panel TP Cx2, VDCy1, VDCy2, and furthermore, a current value flowing through the two resistive films TPx, TPy is measured, and when the measured value exceeds a specified value, two positions on the touch panel TP are measured. Current detection circuits CDCx and CDCy are provided for determining that an abnormal input has been made when the above touch point or the surface is touched.
[0021]
Specifically, the electrode Y1 is connected to the electronic switch SWy1, the electronic switch SWy1 is connected to the power supply Vc via the current detection circuit CDCy, and the connection point between the electrode Y1 and the electronic switch SWy1 is connected to the voltage detection circuit VDCx1. Have been. The electrode Y2 paired with the electrode Y1 is connected to a circuit ground GND via an electronic switch SWy2, and a connection point between the electrode Y2 and the electronic switch SWy2 is connected to a voltage detection circuit VDCx2. The electrode X1 is connected to an electronic switch SWx1, the electronic switch SWx1 is connected to a power supply Vc via a current detection circuit CDCx, and a voltage detection circuit VDCy1 is connected to a connection point between the electrode X1 and the electronic switch SWx1. . The electrode X2 paired with the electrode X1 is connected to a circuit ground GND via an electronic switch SWx2, and a connection point between the electrode X2 and the electronic switch SWx2 is connected to a voltage detection circuit VDCy2.
[0022]
The operation of the analog resistive touch panel configured as described above during normal input (one point pressed) and abnormal input (touched at two or more touch points or touched on a surface) will be described.
[0023]
First, when the electronic switches SWx1 and SWx2 in FIG. 1 are turned on and the electronic switches SWy1 and SWy2 are turned off, as shown in FIG. 2A, the power supply Vc is applied to the electrode X1, and the circuit ground GND is applied to the electrode X2. Are connected, and the electrodes Y1 and Y2 are connected to the voltage detection circuits VDCx1 and VDCx2. In this state, when a normal input is made at one touch point 50, in the X direction from the power supply Vc to the circuit ground GND via the electrode X1, the resistance values Rx1 and Rx2 divided at the touch point 50, and the electrode X2. Electric current flows. That is, in the voltage detection circuits VDCx1 and VDCx2, the voltage detection circuits VDCx1 and VDCx2 can detect the voltage values Vx1 and Vx2 (Equation (13) described in the related art) divided by the resistance values Rx1 and Rx2. At this time, the current detection circuit CDCx for detecting the current flowing through the resistive film TPx can detect the next current.
[0024]
Ix = Vc / (Rx1 + Rx2) (1)
As is clear from the description of the characteristics of the analog resistive touch panel in the related art, the resistance value of Rx1 + Rx2 (that is, the resistance value between the electrodes X1 and X2) at the time of normal input (one-point pressing) is arbitrary. It is constant even if the point is touched. That is, the current Ix flowing through the resistive film TPx is also constant according to the equation (13) described in the related art.
[0025]
On the other hand, when the electronic switches SWx1 and SWx2 are in the ON state and the electronic switches SWy1 and SWy2 are in the OFF state, and two places 50A and 50B on the touch panel TP are touched at the same time as shown in FIG. , The resistance value of the resistive film TPx is divided into Rx3, Rx4, and Rx5 based on the two touch points 50A and 50B on the touch panel TP. As described above, since the resistance value of the resistive film TPx is constant, the following equation holds.
[0026]
Rx3 + Rx4 + Rx5 = Rx1 + Rx2 (2)
Here, the resistance value Z between the electrodes X1 and X2 will be considered. Since the two resistive films TPx and TPy are in contact at the two touch points 50A and 50B on the touch panel TP, the resistance value Ryp on the resistive film TPy is changed to the resistance value Rx4 on the resistive film TPx. And are connected in parallel. Therefore, when the resistance value Z between the electrodes X1 and X2, that is, the combined resistance Z of Rx3, Rx4, Rx5, and Ryp is compared with the resistance value Rx1 + Rx2 of the resistive film TPx, the following equation is established.
[0027]
Combined resistance of Rx3, Rx4, Rx5, Ryp Z ≦ Rx1 + Rx2 (3)
Therefore, the current value Ix # detected by the current detection circuit CDCx can be derived from the equations (1), (2), and (3) as follows.
[0028]
Ix♯ ≧ Ix (4)
So far, two points 50A and 50B on the touch panel TP have been described as being touched. However, even when two or more points on the touch panel TP are touched or an abnormal input is touched on the surface, all of the expressions ( 4) will hold.
[0029]
Next, when the electronic switches SWx1 and SWx2 in FIG. 1 are turned off and the electronic switches SWy1 and SWy2 are turned on, as shown in FIG. 3A, the power source Vc is applied to the electrode Y1, and the circuit ground is applied to the electrode Y2. GND is connected, and the electrodes X1 and X2 are connected to the voltage detection circuits VDCy1 and VDCy2. In this state, when a normal input is made at one touch point 50, in the Y direction from the power supply Vc to the circuit ground GND via the electrode Y1, the resistance values Ry1, Ry2 divided at the touch point 50, and the electrode Y2. Electric current flows. That is, the voltage detection circuits VDCy1 and VDCy2 can detect the voltage values Vy1 and Vy2 divided by the resistance values Ry1 and Ry2, and at this time, the current detection circuit CDCy for detecting the current flowing through the resistive film TPy , The next current can be detected.
[0030]
Iy = Vc / (Ry1 + Ry2) (5)
In addition, similarly to the resistance value of Rx1 + Rx2 at the time of normal input (one-point pressing) (that is, the resistance value between the electrodes X1 and X2), the resistance value of Ry1 + Ry2 at the time of normal input (one-point pressing) (that is, the electrode Y1). , Y2) is constant even if any point is touched. That is, the current Iy flowing through the resistive film TPy is also constant.
[0031]
On the other hand, when the electronic switches SWx1 and SWx2 are in the OFF state and the electronic switches SWy1 and SWy2 are in the ON state, and two places 50C and 50D on the touch panel TP are simultaneously touched as shown in FIG. , The resistance value of the resistive film TPy is divided into Ry3, Ry4, and Ry5 based on two touch points 50C and 50D on the touch panel TP. As described above, since the resistance value of the resistive film TPy is constant, the following equation holds.
[0032]
Ry3 + Ry4 + Ry5 = Ry1 + Ry2 (6)
The resistance value Z between the electrodes Y1 and Y2 is the same as the resistance value Z between the electrodes X1 and X2, and the two resistive films TPx and TPy are in contact at two touch points 50C and 50D on the touch panel TP. Therefore, the resistance value Rxp on the resistance film TPx is connected in parallel with the resistance value Ry4 on the resistance film TPy. Therefore, when the resistance value Z between the electrodes Y1 and Y2, that is, the combined resistance Z of Ry3, Ry4, Ry5 and Rxp is compared with the resistance value Ry1 + Ry2 of the resistive film TPy, the following equation is established.
[0033]
Combined resistance of Ry3, Ry4, Ry5, Rxp Z ≦ Ry1 + Ry2 (7)
Therefore, the current value Iy # detected by the current detection circuit CDCy can be derived from the equations (5), (6), and (7) as follows.
[0034]
Iy♯ ≧ Iy (8)
As described above, when the input operation to the analog resistive touch panel is an abnormal input operation (touched at two or more touch points or touched on the surface), the current detected by the current detection circuits CDCx and CDCy Since the value is larger than that at the time of normal input (one point pressed), it is possible to accurately measure whether the input is normal or abnormal.
[0035]
【The invention's effect】
As is apparent from the above description, according to the abnormal input detection device for an analog resistive touch panel of the present invention, when an abnormal input operation is performed by touching at two or more touch points on the touch panel or touching the surface, The value of the current flowing through the two resistive films constituting the resistive touch panel increases, and the current value can be detected by the current detecting circuit, so that it can be determined that an abnormal input has been performed.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram showing a preferred embodiment of an abnormal input detection device for an analog resistive touch panel according to the present invention.
2A and 2B are diagrams illustrating an operation principle of an abnormal input detection device for an analog resistive touch panel according to the present invention, in which FIG. 2A is a diagram illustrating normal input detection in the X direction of the touch panel, and FIG. Explanatory drawing of abnormal input detection.
3A and 3B are diagrams illustrating the operation principle of an abnormal input detection device for an analog resistive touch panel according to the present invention, wherein FIG. 3A is a diagram illustrating normal input detection in the Y direction of the touch panel, and FIG. Explanatory drawing of abnormal input detection.
4A and 4B are diagrams illustrating a position detection circuit of an analog resistive touch panel, wherein FIG. 4A is a structural diagram, and FIG. 4B is a conceptual diagram.
FIG. 5 is a conceptual diagram showing a position detection circuit of a conventional analog resistive touch panel.
6A and 6B are diagrams illustrating an operation principle of a position detection circuit of a conventional analog resistive touch panel, wherein FIG. 6A is an explanatory diagram of position detection of the touch panel in the X direction, and FIG. FIG.
7A and 7B are diagrams showing an abnormal input operation of a position detection circuit of a conventional analog resistive touch panel, wherein FIG. 7A is an explanatory diagram of a voltage measurement principle, and FIG. 7B is an explanatory diagram of a voltage detection position.
[Explanation of symbols]
.... Touch point TP... Analog resistive touch panel TPx, TPy... Two resistive films X1, X2. ······ Electrode SWx1, SWx2, SWy1, SWy2 in the Y direction of the touch panel ··· Electronic switch Vc ····· Reference voltage Vx, Vy ····· Voltage detection circuits Ax and Ay ..Current detection circuits

Claims (1)

An analog resistive touch panel (TP) composed of two resistive films (TPx, TPy) that are uniformly distributed in resistance and are attached and touched at minute intervals and touched at a touch point (50); An electronic switch (SWx1, SWx2) for alternately applying a reference voltage (Vc) to each electrode (X1, X2, Y1, Y2) in the X direction and Y direction of the touch panel and each electrode in the X direction and Y direction. , SWy1, SWy2) and voltage detection circuits (VDCx1, VDCx2, VDCy1, VDCy2) for detecting a voltage between the electronic switch and the touch point and detecting a position of the touch panel.
The current value flowing through the two resistive films is measured, and when the measured value is equal to or greater than a specified value, when the touch panel is touched at two or more touch points or on a surface. An abnormal input detection device for an analog resistive touch panel, comprising a current detection circuit (CDCx, CDCy) for determining that an abnormal input has been made.

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