JP7236306B2 - touch panel device - Google Patents

Description

The present invention relates to a touch panel device.

A resistive touch panel device detects touch coordinates by generating a potential corresponding to the position where a pair of resistive films come into contact with each other during a touch input (for example, Patent Document 1). With the diversification of the uses of touch panel devices, there is a demand for touch panel devices in which the touch input area is trapezoidal instead of the usual square or rectangular shape.

On the other hand, for example, a means for forming a trapezoidal touch input area by covering a part of a square or rectangular resistive film with a cover or the like is used. For example, Patent Document 2 describes a trapezoidal capacitive-coupling coordinate input panel.

JP 2016-110223 A JP 2011-8757 A

However, according to the above means, since unused portions exist in the resistive film, not only is there a useless portion, but it is also difficult to reduce the size of the touch panel device. This problem can be avoided by forming the resistive film into a trapezoidal shape, but since the potential distribution of the resistive film is distorted by the arrangement of the electrodes according to the trapezoidal shape, the coordinates of the touch input (hereinafter referred to as "input coordinates") detection accuracy may decrease.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a touch panel device with improved detection accuracy of input coordinates.

In one aspect, the touch panel device includes a trapezoidal first resistive film, a set of electrodes along a pair of opposite sides of the first resistive film, which are legs of the trapezoidal shape, and the set of electrodes. a pair of connecting portions connected to the pair of opposite sides of the first resistive film; and a pair of connecting portions that contact the first resistive film according to a touch input and connect the first resistive film by a voltage between the pair of electrodes. and a second resistive film having an electric potential corresponding to the contact position of the pair of connection portions, wherein the pair of connecting portions are spaced apart from each other between the pair of electrodes and the pair of opposite sides of the first resistive film. The pair of connecting portions has a higher resistance value at a position closer to the shorter opposite side of the other pair of opposite sides of the first resistive film.

According to the present invention, it is possible to improve the detection accuracy of the input coordinates of the touch panel device.

1 is a configuration diagram showing an example of a touch panel device; FIG. It is a block diagram which shows an example of a touch panel. It is a figure which shows the upper resistive film of a comparative example. It is a figure which shows the upper resistive film of an Example. It is a figure which shows the lower resistive film of a comparative example. It is a figure which shows the lower resistive film of an Example.

(Configuration of touch panel device)
FIG. 1 is a configuration diagram showing an example of a touch panel device. The touch panel device includes a touch panel 100 , a display 101 and a control device 6 .

The touch panel 100 is of a resistive type and has an input surface for receiving touch input from a user. The display 101 is, for example, a liquid crystal monitor, and has a display surface that overlaps the input surface of the touch panel 100 when viewed from the front.

The control device 6 is, for example, a microcontroller, and includes a processor 4 such as a CPU (Central Processing Unit), a ROM (Read Only Memory) 50 storing programs executed by the processor 4, and a RAM (Random Access Memory) 51 and a communication port 52 . The processor 4 is connected to the touch panel 100 and the display 101 , and is also connected to the ROM 50 , the RAM 51 and the communication port 52 via the bus 60 .

When the processor 4 reads a program from the ROM 50 when the power is turned on, a control section 40, a detection section 41, and a display section 43 are formed as functions. The control unit 40 controls, for example, switches that drive the touch panel 100 . The detection unit 41 detects input coordinates within the input surface of the touch panel 100 based on the potential of the touch panel 100 . The display unit 43 performs display processing for the display 101 .

Processor 4 communicates with a host device through communication port 52 . A host device is, for example, a computer that executes an application using a touch panel device.

The detector 41 notifies the host device of the input coordinates. For example, the host device outputs display data corresponding to the input coordinates to the display section 43 , and the display section 43 displays an image of the display data on the display 101 .

(Configuration of touch panel 100)
FIG. 2 is a configuration diagram showing an example of the touch panel 100. As shown in FIG. The touch panel 100 includes an upper resistive film 10, a lower resistive film 20, electrodes 11, 12, 21, 22, connection portions 23a, 23b, transparent substrates 13, 24, and switches 31, 32, 34, 35 facing each other. ing. Regarding the coordinate system, the direction parallel to the electrodes 11 and 12 is defined as the X direction, and the direction orthogonal to the X direction is defined as the Y direction.

The transparent substrates 14 and 24 are, for example, trapezoidal PET (Polyethylene Terephthalate) films. An upper resistive film 10 and electrodes 11 and 12 are provided on the surface of one transparent substrate 14, and a lower resistive film 20, connecting portions 23a and 23b, and electrodes 21 and 22 are provided on the surface of the other transparent substrate 24. is provided.

The upper resistive film 10 and the lower resistive film 20 are formed of a transparent thin film such as indium tin oxide (ITO) and have a trapezoidal shape. The upper resistive film 10 is an example of a second resistive film and a third resistive film, and the lower resistive film 20 is an example of a first resistive film and a fourth resistive film. Moreover, there is no limitation on the arrangement of the upper resistive film 10 and the lower resistive film 20 in the vertical direction.

Examples of the switches 31, 32, 34, and 35 include, but are not limited to, transistors. The switches 31 , 32 , 34 , and 35 have bases connected to the controller 40 and are on/off controlled by the controller 40 .

A pair of electrodes 11 and 12 are provided at both ends of the upper resistive film 10 in the Y direction. The electrodes 11 and 12 are made of ITO thin films, for example. The upper resistive film 10 is divided into a plurality of belt-like film pieces 10a connecting the electrodes 11 and 12, respectively.

A collector of the switch 31 and the detector 41 are connected to the electrode 11 . The emitter of switch 31 is grounded. A collector of a switch 32 is connected to the electrode 12 and a power supply voltage Vcc is applied to the emitter of the switch 32 .

A pair of electrodes 21 and 22 are provided at both ends of the lower resistive film 20 in the X direction. The electrodes 21 and 22 are connected to the lower resistive film 20 through connecting portions 23a and 23b, respectively.

The connecting portions 23a and 23b are formed of a transparent thin film such as ITO. A collector of a switch 35 is connected to the electrode 22 and a power supply voltage Vcc is applied to the emitter of the switch 35 . The detector 41 and the collector of the switch 34 are connected to the electrode 21 . The emitter of switch 34 is grounded.

The upper resistive film 10 and the lower resistive film 20 are overlapped so as to face each other with a dot spacer (not shown) interposed therebetween. When the input surface S is viewed from the front, the trapezoidal shapes of the upper resistive film 10 and the lower resistive film 20 overlap each other. The upper resistive film 10 and the lower resistive film 20 are separated by a distance defined by the thickness of the dot spacer, and come into contact with each other in response to touch input using a touch pen or the like. At this time, the coordinates of the contact point P of the upper resistive film 10 and the lower resistive film 20 match the input coordinates within the input surface S by touch input.

The detection unit 41 detects the X coordinate of the contact point P based on the potential gradient Vx of the lower resistive film 20 in the X direction, and detects the Y coordinate of the contact point P based on the potential gradient Vy of the upper resistive film 10 in the Y direction. .

When detecting the Y coordinate of the contact point P, the control unit 40 turns on the switches 31 and 32 and turns off the switches 34 and 35 . As a result, the power supply voltage Vcc is applied between the electrodes 11 and 12 of the upper resistive film 10, so that a potential gradient Vy is generated in the Y direction. Therefore, the lower resistive film 20 has a potential corresponding to the Y coordinate of the contact point P due to the power supply voltage Vcc. The detection unit 41 acquires the potential of the contact point P via the lower resistance film 20 .

Further, when detecting the X coordinate of the contact point P, the control unit 40 turns on the switches 34 and 35 and turns off the switches 31 and 32 . As a result, the power supply voltage Vcc is applied between the electrodes 21 and 22 of the lower resistive film 20, thereby generating a potential gradient Vx in the X direction. Therefore, the upper resistive film 10 has a potential corresponding to the X coordinate of the contact point P due to the power supply voltage Vcc. The detection unit 41 acquires the potential of the contact point P via the upper resistive film 10 .

The detection unit 41 converts the potentials of the contact point P in the X direction and the Y direction into digital values, and detects the X coordinate and the Y coordinate of the contact point P based on the converted values. The X and Y coordinates are calculated based on the distances between the electrodes 11, 12, 21 and 22 from the ratio of each potential to the power supply voltage Vcc.

For example, the control unit 40 switches between the state of detecting the X coordinate of the contact point P and the state of detecting the Y coordinate of the contact point P at regular intervals, for example. Therefore, the set of switches 31 and 32 and the set of switches 34 and 35 are alternately turned on and off.

The potentials of the upper resistive film 10 and the lower resistive film 20 change linearly in the Y direction and the X direction respectively due to the configuration described below, so that the coordinates of the contact point can be detected with high accuracy. On the other hand, in the upper resistive film 10' and the lower resistive film 20' of the comparative example, the potential changes nonlinearly in the Y direction and the X direction, respectively, so that the coordinates of the contact point can be detected with high accuracy. difficult.

(Upper resistive film 10' of the comparative example)
FIG. 3 is a diagram showing an upper resistive film 10' of a comparative example. Reference G1a indicates a plan view of the upper resistive film 10', and reference G1b indicates a change in potential Ey of the upper resistive film 10' with respect to the Y coordinate.

The upper resistive film 10' has a trapezoidal shape, and electrodes 11 and 12 are provided at the ends in the Y direction, like the upper resistive film 10 of the embodiment. The electrodes 11 and 12 are provided along a pair of opposite sides of the upper resistive film 10', which is the base of the trapezoidal shape. For example, the electrode 11 is along the lower base of the trapezoidal shape and the electrode 12 is along the upper base of the trapezoidal shape. Therefore, the electrode 11 is longer than the electrode 12 in the X direction. Further, unlike the upper resistive film 10 of the embodiment, the upper resistive film 10' is not divided into a plurality of film pieces 10a. The electrodes 11 and 12 are centered in the X direction, but they may be displaced.

When a power supply voltage Vcc is applied between the electrodes 11 and 12, a potential gradient Vy along the Y direction is generated in the upper resistive film 10'. When the electrode 11 is on the high potential side and the electrode 12 is on the low potential side, the potential distribution in the upper resistive film 10' is represented by equipotential lines Ly' convex to the negative side in the Y direction.

Since the electrodes 11 and 12 have different lengths, the distance between the electrodes 11 and 12 varies depending on the position on the electrodes 11 and 12 . For example, the distance d2 between the positions near the center of the electrodes 11 and 12 is shorter than the distance d1 between the positions near the ends of the electrodes 11 and 12 . Therefore, the upper resistive film 10' has a portion where the potential Ey changes nonlinearly with respect to the Y coordinate.

A characteristic Px1 indicates a change in the potential Ey at the X coordinate x1 near the end of the electrode 12, and a characteristic Px2 indicates a change in the potential Ey at the X coordinate x2 (>x1) near the center of the electrodes 11 and 12. The Y coordinate range of the characteristics Px1 and Px2 is from YA to YB (>YA).

The potential Ey changes linearly with respect to the Y coordinate in the characteristic Px1, but the potential Ey changes nonlinearly with respect to the Y coordinate in the characteristic Px2. Therefore, although the Y coordinate YC is the same, the potential Ey differs according to the X coordinates x1 and x2. For example, the potential Ey at the contact point P of the Y coordinate YC is Ec1 when the X coordinate is x1, and is Ec2 (>Ec1) when the X coordinate is x2.

Therefore, the detection unit 41 cannot accurately detect the Y coordinate of the contact point P from the potential Ey.

(Upper resistive film 10 of the example)
FIG. 4 is a diagram showing the upper resistive film 10 of the example. Reference G2a indicates a plan view of the upper resistive film 10, and reference G2b indicates a change in potential Ey of the upper resistive film 10 with respect to the Y coordinate. In FIG. 4, the same reference numerals are given to the same components and coordinates as in FIG. 3, and the description thereof will be omitted.

Unlike the upper resistive film 10' of the comparative example, the upper resistive film 10 is divided into a plurality of film pieces 10a connecting the electrodes 11 and 12 respectively. The film piece 10a is obtained, for example, by etching the upper resistive film 10 after the upper resistive film 10 is formed on the transparent substrate 13 in the manufacturing process. Since, for example, a constant gap is provided between the film pieces 10 a by etching, the film pieces 10 a are electrically connected to each other only through the electrodes 11 and 12 .

The film pieces 10a have different widths at both ends in the Y direction, and thus have a trapezoidal shape. Therefore, when the power supply voltage Vcc is applied between the electrodes 11 and 12, the potentials of the film pieces 10a do not affect each other, and the position in the extending direction of the film piece 10a, that is, the distance from the electrodes 11 and 12 is It varies linearly. Therefore, the potential distribution in the upper resistive film 10 is represented by equipotential lines Ly parallel to the X direction.

Characteristics Px1 and Px2 indicate changes in potential Ey in the Y direction at X coordinates x1 and x2. The characteristics Px1 and Px2 are similar because the equipotential lines Ly are parallel to the X direction. Since the potential Ey changes linearly with respect to the position on the film piece 10a, it also changes linearly with respect to the Y direction. Therefore, for example, if the Y coordinate YC is common, the common potential Ec can be obtained even if the X coordinates x1 and x2 are different. Therefore, the Y coordinate can be detected with high accuracy from the potential Ey.

In this manner, the upper resistive film 10 is divided into a plurality of film pieces 10a so as to have a uniform potential Ey along a pair of opposite sides, which are the bases of the trapezoidal shape. Therefore, the potential Ey changes according to the Y coordinate without being affected by the X coordinate. This is possible, for example, by dividing the upper resistive film 10 into a sufficient number of divisions so that the film pieces 10a can be theoretically regarded as rectangular conductors.

However, since the shape of the film piece 10a is closer to a rectangle than the shape of the upper resistive film 10 from which it is divided, if the upper resistive film 10 is divided into a plurality of film pieces 10a, the detection accuracy of the Y coordinate is increased regardless of the number of divisions. be improved. The width and interval of each film piece 10a are preferably constant, but may be different.

(Lower resistive film 20' of the comparative example)
FIG. 5 is a diagram showing a lower resistive film 20' of a comparative example. Reference G3a indicates a plan view of the lower resistive film 20', and reference G3b indicates a change in potential Ex of the lower resistive film 20' with respect to the X coordinate.

The lower resistive film 20' has a trapezoidal shape, and electrodes 21 and 22 are provided at the ends in the X direction, like the lower resistive film 20 of the embodiment. The electrodes 21 and 22 are provided along a pair of opposite sides of the lower resistive film 20', which are trapezoidal legs. Also, unlike the embodiment, the lower resistive film 20' is not provided with the connecting portions 23a and 23b. Therefore, the electrodes 21 and 22 are directly connected to the lower resistive film 20'.

When a power supply voltage Vcc is applied between the electrodes 21 and 22, a potential gradient Vx along the X direction is generated in the lower resistive film 20'. Here, it is assumed that the electrode 22 is on the high potential side and the electrode 21 is on the low potential side. The potential distribution in the upper resistive film 10 extends along the Y direction because the distance between the electrodes 21 and 22 changes along the Y direction because the electrodes 21 and 22 are arranged in the shape of the letter V. It is represented by an equipotential line Lx' distorted from the outside toward the center of the lower resistive film 20' in the X direction.

A characteristic Py1 indicates a change in the potential Ex at the Y coordinate y1 near the lower ends of the electrodes 21 and 22, and a characteristic Py2 indicates a change in the potential Ex at the Y coordinate y2 (>y1) near the center of the electrodes 21 and 22. The X-coordinate range of the characteristic Py1 is from XA to XB (>XA), and the X-coordinate range of the characteristic Py2 is from XA' to XB' (>XA').

The potential Ex changes nonlinearly along the X direction. Here, the potential Ex of the X-coordinates XA and XA' has a common value Emax because the contact point is located on the electrode 22 . Therefore, the same potential Emax is obtained for different X-coordinates XA and XA'.

The potential Ex at the X coordinate XA' is Emax when the Y coordinate is y2, but is Eu (<Emax) when the Y coordinate is y1. Therefore, although the X-coordinate XA' is the same, the potential Ex differs depending on the Y-coordinates y1 and y2.

On the other hand, the potential Ex of the X-coordinates XB and XB' has a common value Emin because the contact point is located on the electrode 21 . Therefore, the same potential Emin is obtained for different X-coordinates XB and XB'.

The potential Ex at the X coordinate XB' is Emin when the Y coordinate is y2, but is Ed (>Emin) when the Y coordinate is y1. Therefore, although the X-coordinate XB' is the same, the potential Ex differs depending on the Y-coordinates y1 and y2.

Therefore, the detection unit 41 cannot accurately detect the X coordinate of the contact point from the potential Ex.

(Lower resistive film 20 of the example)
FIG. 6 is a diagram showing the lower resistive film 20 of the example. Reference G4a indicates a plan view of the lower resistive film 20, and reference G4b indicates a change in potential Ex of the lower resistive film 20 with respect to the X coordinate. In FIG. 6, the same reference numerals are given to the configurations and coordinates that are common to those in FIG. 5, and the description thereof will be omitted.

Unlike the lower resistive film 20' of the comparative example, the lower resistive film 20 is connected to the electrodes 21 and 22 via connecting portions 23a and 23b, respectively. The connection portions 23a and 23b have higher resistance values at positions closer to the shorter opposite side (that is, the upper base of the trapezoid) among the pair of opposite sides of the lower resistive film 20 that are the base of the trapezoid.

Therefore, the voltage drop of the lower resistive film 20 becomes higher at a position closer to the shorter opposite side, and equipotential lines Lx along the Y direction are obtained without being distorted. Therefore, the potential Emax at the X coordinate XA and the potential Eu' (<Emax) at the X coordinate XA' can be made different, and the potential Emin at the X coordinate XB and the potential Ed' (>Emin) at the X coordinate XB' can be made different. be able to. Furthermore, each potential Ex of the characteristics Py1 and Py2 can similarly be linearly changed in the X direction within the range of the X coordinates XA to XB'.

By changing the resistance values of the connecting portions 23a and 23b in the Y direction in this manner, the potential Ex can be linearly changed according to the X coordinate, not depending on the Y coordinate. Therefore, the detection unit 41 can detect the X coordinate of the contact point from the potential Ex with high accuracy.

The connecting portions 23a, 23b include, for example, a plurality of bridges 230a, 230b. Each bridge 230a, 230b is an example of a resistor, and connects between a pair of opposite sides of the lower resistive film 20, which are trapezoidal legs, and the electrodes 22, 21, respectively.

The distances Da and Db between the bridges 230a and 230b are wider as they are closer to the shorter opposite sides of the pair of opposite sides of the lower resistive film 20 which are the bases of the trapezoidal shape. In other words, the distances Da and Db between the bridges 230a and 230b are wider as they are closer to the upper base of the trapezoidal shape of the lower resistive film 20 .

The widths Wa and Wb of the bridges 230a and 230b are narrower toward the shorter side of the pair of opposite sides of the lower resistive film 20, which are the bases of the trapezoidal shape. That is, the widths Wa and Wb of the bridges 230a and 230b are narrower as they are closer to the upper base of the trapezoidal shape of the lower resistive film 20 .

Therefore, the resistance value of the connection portions 23a and 23b can be increased with a simple structure as it approaches the upper base of the trapezoidal shape of the lower resistive film 20. FIG. In order to change the resistance value, instead of or in addition to the gaps Da and Db and the widths Wa and Wb of the bridges 230a and 230b, the thickness and material of the bridges 230a and 230b may be changed along the Y direction. . In this example, both the gaps Da and Db and the widths Wa and Wb of the bridges 230a and 230b are changed along the Y direction, but only one of them may be changed.

In this way, the connection portions 23a and 23b have higher resistance values closer to the upper base of the trapezoidal shape of the lower resistive film 20 so that the lower resistive film 20 has a uniform potential Ex along the Y direction. . Therefore, the potential Ex changes according to the X coordinate without being affected by the Y coordinate. This eliminates the distortion of the equipotential lines Lx' of the comparative example, for example, and makes the potential Ex uniform regardless of the Y coordinate. This is possible by setting the distribution in one Y direction.

However, at least one of the gaps Da and Db and the widths Wa and Wb of the bridges 230a and 230b should be set so that the voltage drop across the lower resistive film 20 increases at positions closer to the upper base of the trapezoidal shape of the lower resistive film 20. For example, it is possible to reduce the deviation of the potential Ex in the Y direction caused by arranging the electrodes 22 and 21 in the V shape without performing the detailed setting as described above. Therefore, the detection accuracy of the X coordinate is improved.

The embodiments described above are examples of preferred implementations of the present invention. However, the present invention is not limited to this, and various modifications can be made without departing from the spirit of the present invention.

10, 10' upper resistive film 10a film piece 20, 20' lower resistive film 11, 12, 21, 22 electrodes 23a, 23b connecting portions 230a, 230b bridge

Claims (3)

a trapezoidal first resistive film;
a pair of electrodes along a pair of opposite sides of the first resistive film, which are legs of the trapezoidal shape;
a pair of connecting portions that connect the pair of electrodes to the pair of opposite sides of the first resistive film;
a second resistive film that is in contact with the first resistive film in response to a touch input and has a potential corresponding to a contact position with the first resistive film by a voltage between the pair of electrodes;
the pair of connecting portions includes a plurality of resistors that connect the pair of electrodes and the pair of opposite sides of the first resistive film with a space therebetween;
The touch panel device, wherein the pair of connection portions has a higher resistance value at a position closer to a shorter side of the other pair of opposite sides of the first resistive film. 2. The touch panel device according to claim 1, wherein the distance between the plurality of resistors is wider toward the shorter opposite side. 3. The touch panel device according to claim 1, wherein widths of the plurality of resistors are narrower toward the shorter opposite side.

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