JP2005274225A - Touch panel inspection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a touch panel inspection device for accurately inspecting electrical characteristics, such as resistance values, on the whole of a touch panel by accurately detecting a prescribed touch input position on the touch panel of a resistance film type. <P>SOLUTION: In this touch panel inspection device 20, a voltage from a constant-voltage power supply 31 is impressed on a touch panel body 22 of a resistance film type, comprising a first resistance film 25 having a pair of X-axis electrodes 27a and 27b and a second resistance film 26 having a pair of Y-axis electrodes 28a and 28b, to measure an output voltage value corresponding to a prescribed input position, thereby inspecting the electrical characteristics of the panel body 22. This inspection device 20 is equipped with a reversal inspection means 21 for changing over the polarity of the power supply 31 for supplying power to the panel body 22 by a second change-over switch 33 to shift the voltage value to the reversed polarity side for inspection when the voltage value is equal to or less than a prescribed threshold. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a touch panel inspection device mounted on display and input screens of various electronic devices such as ATM and car navigation, and more particularly, touch panel inspection for inspecting electrical characteristics of input position coordinates in a resistive touch panel. It relates to the device.

  The touch panel is an input device that is attached to the front surface of a display such as a liquid crystal display and touches this surface with a finger or a pen. Various sensors are used as means for detecting the input position. The main detection means include a resistance film method, an optical method, a capacitance method, etc. Among them, a low-cost but relatively high performance resistance film type touch panel device is widely used. ing. The resistive film type is classified into an analog type and a digital type.

  In an analog resistance film type touch panel, there may be an error in the accuracy of the touch input position due to variations in the resistance value of the resistance film itself constituting the touch panel or variations in resistance value due to processing defects occurring in the manufacturing process. In order to inspect the resistance value characteristic of such a touch panel, a touch panel inspection apparatus 1 as shown in Patent Document 1 or the like is used. FIG. 5 shows a general configuration of the touch panel inspection apparatus 1. The touch panel inspection apparatus 1 of this example includes a power supply unit 3 that supplies a driving voltage to the touch panel body 2 and a control unit 4 that detects an output voltage at a touch position on the touch panel body 2.

  The touch panel body 2 includes a first resistance film 5 that detects an X-axis voltage value at a touch input point, and a second resistance film 6 that detects a Y-axis voltage value. The second resistive film 6 is disposed to face the gap with a slight gap. By pressing the touch input point with a point member such as a pen, the first resistance film 5 and the second resistance film 6 in the pressed portion come into contact with each other, and a predetermined voltage is output. Here, when a voltage is applied between the X-axis electrodes, a potential gradient is generated in the first resistance film 5. Then, the voltage at this input point is read by the Y-axis electrode and processed by the control unit 4 to calculate the X-axis position on the first resistance film 5. Next, a voltage is applied from the power supply unit 3 between the Y-axis electrodes of the second resistance film 6, and the voltage is read by the X-axis electrodes in the same manner as described above, and the Y-axis position on the second resistance film 6 is calculated. FIG. 6 is a graph showing an ideal relationship between the position of the touch input point on the touch panel body 2 and the output voltage value at that time.

  The power supply unit 3 includes a constant voltage power supply 11 and a changeover switch 12, and the changeover switch 12 monitors switching of a voltage supplied to the first resistance film 5 or the second resistance film 6 and a touch input position. Detection switching is performed.

Further, the control unit 4 converts the output voltage at the touch input position into a digital value and monitors the A / D converter 13 and the CPU 15, and the I / O port 14 that sends a switching signal of the changeover switch 12. Etc.
JP 2001-313696 A

  By the way, in the conventional touch panel inspection apparatus 1, one of the first resistance film 5 between the X-axis electrodes or the second resistance film 6 between the Y-axis electrodes is connected to GND (0 volts), and the other is connected to Vcc. The output voltage value at the touch input position is detected in a linear potential gradient between 0 volt and Vcc.

  However, as the output voltage at the touch input position approaches 0 volts, the voltage change amount becomes minute, so that the influence of a minute error during measurement increases. For this reason, accurate measurement of the touch input position may be difficult. In addition, when trying to increase the measurement accuracy in such a situation, it is necessary to use a higher resolution A / D converter and to speed up the processing in the CPU. There is a problem that man-hours increase.

  Accordingly, an object of the present invention is to provide a touch panel inspection apparatus capable of accurately inspecting electrical characteristics such as a resistance value of the entire touch panel by accurately detecting a predetermined touch input position on the resistive touch panel. Is to provide.

  In order to solve the above problems, a touch panel inspection apparatus according to the present invention applies a power supply voltage to a resistive film touch panel including a first resistive film having a pair of X-axis electrodes and a second resistive film having a pair of Y-axis electrodes. Then, in the touch panel inspection device that inspects the electrical characteristics of the resistive touch panel by measuring an output voltage value corresponding to a predetermined input position, when the output voltage value is a predetermined threshold value or less, Inversion inspection means for switching the polarity of the power supply voltage supplied to the resistive touch panel and shifting the output voltage value to the inverted polarity side for inspection is provided.

  The inversion inspection means monitors the output voltage value of the input position and switches the switching timing of the switching means, while switching the polarity of the power supply voltage supplied between the X-axis electrodes or the Y-axis electrodes. And a control means.

  The switching means includes a switch circuit that alternately switches the polarity of the voltage supplied from the power supply voltage between the X-axis electrodes or between the Y-axis electrodes based on a switching signal from the control means.

  The control means detects an output voltage value corresponding to the input position and converts it to a digital value, a preset threshold voltage and a detection converted by the A / D converter A comparison unit that compares the voltage value and an output unit that sends a switching signal to the switching unit are provided.

  The threshold is set to 49 to 51% of the power supply voltage.

  The touch panel inspection apparatus according to the present invention applies a power supply voltage to a resistance film touch panel including a first resistance film having a pair of X-axis electrodes and a second resistance film having a pair of Y-axis electrodes, and puts the power supply voltage at a predetermined input position. In a touch panel inspection apparatus for inspecting electrical characteristics of the resistive touch panel by measuring a corresponding output voltage value, a potential compensation means for shifting an output voltage value detected from the predetermined input position to a high potential side by a certain amount It is provided with.

  The potential compensation means includes a voltage dividing resistor inserted in series between the power supply voltage and the X-axis electrode or the Y-axis electrode, and the voltage dividing ratio is set to 1/5 to 1/20.

  According to the touch panel inspection device of the present invention, when an electrical characteristic is inspected by applying a certain amount of power supply voltage (Vcc) from GND (0 volt) to the touch panel body, the absolute value of the output voltage in the vicinity of the 0 volt. By ensuring the amount above a certain level, it became possible to perform highly accurate linearity inspection.

  FIG. 1 is a diagram illustrating a configuration of a touch panel body 22 and a touch panel inspection apparatus 20 according to the first embodiment connected to the touch panel body 22. The touch panel inspection apparatus 20 according to this embodiment includes a power supply voltage (constant voltage power supply 31) connected to the touch panel body 22 formed of a pair of rectangular resistance layers (first resistance film 25 and second resistance film 26), A switching unit (switching circuit unit 23) for switching the connection of the constant voltage power supply 31 and an inversion inspection unit 21 including a control unit (control unit 24) for processing a signal detected by the touch panel body 22 are provided.

  The touch panel body 22 is disposed so as to face each other with a gap (approximately 100 μm to 300 μm) close to each other so that the first resistance film 25 and the second resistance film 26 do not contact each other in a normal state. The first resistance film 25 and the second resistance film 26 are made of, for example, a transparent electrode material in which a transparent conductive film such as ITO (Indium Tin Oxide) is coated on a glass or polyester film. The first resistance film 25 includes a pair of X-axis electrodes 27a and 27b installed on edges facing each other along the X-axis direction. The second resistance film 26 includes Y-axis electrodes 28a and 28b installed on edges facing each other along the Y-axis direction.

  The constant voltage power supply 31 stably supplies a voltage of GND (0 volts) to Vcc (for example, +5 volts) to the touch panel body 22.

  The changeover circuit unit 23 includes a first changeover switch 32 and a second changeover switch 33. The first changeover switch 32 includes signal selection contacts 32a and 32b for connecting the X-axis electrode 27b and the Y-axis electrode 28b to the constant voltage power supply 31 or the empty terminal, respectively, and the X-axis electrode 27a and the Y-axis electrode 28a, respectively. Signal selection contacts 32c and 32d for connection to the constant voltage power supply 31 or the control unit 24 are provided. The second changeover switch 33 includes polarity reversal contacts 33 a and 33 b for switching between the Vcc side and the GND side of the constant voltage power supply 31. The first changeover switch 32 and the second changeover switch 33 are connected via relay contacts 34a and 34b.

  The control unit 24 detects an arbitrary contact point between the first resistance film 25 and the second resistance film 26, and converts an output voltage value at that time into a digital value. The first changeover switch 32 and an I / O port for controlling the switching timing of the second selector switch 33. The operations of the A / D converter 35 and the I / O port 36 are centrally managed by the CPU 37.

  The characteristic point of this embodiment is that the second changeover switch 33 is provided. The second change-over switch 33 has a role of switching the polarity of the constant voltage power supply 31 supplied to the touch panel body 22, and the switching operation is performed when the potential at the contact position of the first resistance film 25 or the second resistance film 26 is a predetermined value. It is performed at the timing below the threshold. The threshold value is set to a level at which the voltage value can be measured by the control unit 24 without error and the A / D conversion accuracy can be sufficiently maintained. For example, if Vcc of the constant voltage power supply 31 is +5 volts, it is set in the range of 2.45 to 2.55 volts.

  Next, a position inspection method at an arbitrary input point P on the touch panel body 22 will be described based on FIG. 1 and FIG. The inspection is performed by pressing with a point member 29 such as a pen from above the first resistance film 25 and bringing it into contact with the second resistance film 26.

  First, position detection processing on the X axis is executed. In this inspection process, a voltage is applied from the constant voltage power supply 31 with the signal selection contacts 32a to 32d of the first changeover switch 32 set to the contact A side, and the contact point is placed between the X-axis electrodes 27a and 27b. The resulting potential gradient is generated. When the voltage at this time is read by the control unit 24 via the Y-axis electrode 28a of the second resistance film 26 and the signal selection contact 32d, it is determined whether the value is higher or lower than a preset threshold value. Holds the state as it is, and controls the second change-over switch 33 so as to invert when it is low. When the setting of the second changeover switch 33 is switched, the voltage is applied again between the X-axis electrodes 27a and 27b, thereby shifting the output voltage to the inverted polarity side to an output voltage of a certain level or higher. Is obtained. In this way, accurate position coordinates on the X axis are calculated.

  Next, the process proceeds to position detection processing on the Y axis. In this inspection process, a voltage is applied from the constant voltage power supply 31 with the signal selection contacts 32a to 32d of the first changeover switch 32 set to the contact B side, and the contact point is between the Y-axis electrodes 28a and 28b. The resulting potential gradient is generated. When the voltage at this time is read by the control unit 24 via the X-axis electrode 27a of the first anti-membrane 25 and the signal selection contact 32c, it is determined whether the value is higher or lower than a preset threshold value. Holds the state as it is, and controls the second change-over switch 33 so as to invert when it is low. When the setting of the second changeover switch 33 is switched, the voltage is applied again between the Y-axis electrodes 28a and 28b, so that the output voltage at a certain level or more is obtained by shifting the output voltage to the inverted polarity side. Is obtained. In this way, accurate position coordinates on the Y axis are calculated.

  FIG. 2 is a graph showing changes in the position detection voltage due to the movement of the point member 29. As shown in this graph, there is no change if the initially measured position detection voltage is equal to or greater than the threshold value (Vs). However, when the position detection voltage is equal to or less than Vs, the position detection voltage is inverted and approaches 0V. It can be detected at a value close to Vcc. Thus, by shifting the low detection voltage in the vicinity of 0V to the Vcc side, a constant detection voltage value can be secured, so that the linearity inspection of the entire touch panel can be performed with little error and high accuracy. It becomes possible.

  The polarity inversion of the voltage supplied from the constant voltage circuit 31 depends on a preset threshold value (Vs). This Vs value is, for example, when the voltage supplied from the constant voltage circuit 31 is 5V. Is in the range of 2.45 to 2.55 V, which is about 1/2.

  In the control unit 24, the voltage value of the X-axis coordinate and the Y-axis coordinate of the input point is converted into a digital value through the A / D converter 35, and compared with threshold data registered in advance by the CPU 37, A change signal is sent from the I / O port 36 to the second changeover switch 33 according to the result. In the control unit 24, the switching operation of the first changeover switch 32 is also performed at the same time. Such a series of inspection procedures may be performed manually, but automatic inspection is possible by programming according to the size and characteristics of the touch panel to be inspected.

FIG. 3 shows a second embodiment of the touch panel inspection apparatus of the present invention. This touch panel inspection device 40 increases the voltage on the lower side of the output voltage value detected from the touch panel body 22 by inserting a series resistor R _B into a constant voltage power supply 31 that supplies a voltage to the touch panel body 22. It is. The resistor R _B is, X-axis electrodes 27a are connected via a GND side and the first changeover switch 32 of the constant voltage source 31, or is inserted between the Y-axis electrode 28a. By inserting a resistor R _B, a voltage supplied from the constant-voltage power supply 31 is divided. As a result, as shown in FIG. 4, the output voltages at the X-axis position on the first resistance film 25 and the Y-axis position on the second resistance film 26 detected from the touch panel body 22 are raised by Rv, and are increased to the GND side. Even when an input point for inspection is set in the vicinity of a certain X-axis electrode 27a or Y-axis electrode 28a, it does not drop to around 0V. Therefore, a voltage value sufficient for digital conversion through the A / D converter 35 of the control unit 24 can be obtained, and the position at the touch input point can be detected with high accuracy. As the voltage dividing resistor R _B , it is preferable to use a precision metal film resistor of a high accuracy type with little measurement error. The resistance value is determined in consideration of the resistance between the X-axis electrode 27a and the X-axis electrode 27b, the resistance between the Y-axis electrode 28a and the Y-axis electrode 28b, the specifications of the constant voltage power supply 31 and the A / D converter 35, and the like. . For example, if the resistance between the X-axis electrodes is 800Ω, the resistance between the Y-axis electrodes is 300Ω, and the supply voltage of the constant voltage power supply 31 is 0 to + 5V, about 40Ω to 60Ω is appropriate. Further, if the resistance R _B to replace the variable type, it can be adjusted according to the level of the output voltage detected.

It is a figure showing composition of a 1st embodiment of a touch panel inspection device concerning the present invention. It is a figure which shows the detection voltage characteristic in the touchscreen inspection apparatus of the said 1st Embodiment. It is a figure which shows the structure of 2nd Embodiment of the touchscreen inspection apparatus which concerns on this invention. It is a figure which shows the detection voltage characteristic in the touchscreen inspection apparatus of the said 2nd Embodiment. It is a figure which shows the structure of the conventional touchscreen inspection apparatus. It is a figure which shows the detection voltage characteristic in the conventional touch panel inspection apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 20 Touchscreen test | inspection apparatus 21 Inversion test | inspection means 22 Touchscreen main body 23 Switching circuit part 24 Control part 25 1st resistance film 26 2nd resistance film 27 X-axis electrode 28 Y-axis electrode 31 Constant voltage power supply 32 1st changeover switch 33 2nd changeover switch

Claims (8)

By applying a power supply voltage to a resistive film touch panel composed of a first resistive film having a pair of X-axis electrodes and a second resistive film having a pair of Y-axis electrodes, and measuring an output voltage value corresponding to a predetermined input position, In the touch panel inspection device for inspecting the electrical characteristics of the resistive touch panel,
Inversion inspection means for switching the polarity of the power supply voltage supplied to the resistive touch panel and shifting the output voltage value to the inverted polarity side when the output voltage value is a predetermined threshold value or less. A touch panel inspection apparatus comprising: The inversion inspection means monitors the output voltage value of the input position and switches the switching timing of the switching means, while switching the polarity of the power supply voltage supplied between the X-axis electrodes or the Y-axis electrodes. The touch panel inspection apparatus according to claim 1, further comprising a control unit. The switch means includes a switch circuit that alternately switches the polarity of the voltage supplied from the power supply voltage between the X-axis electrodes or between the Y-axis electrodes based on a switching signal from the control means. The touch panel inspection apparatus as described. The control means detects an output voltage value corresponding to the input position and converts it to a digital value, a preset threshold voltage and a detection converted by the A / D converter The touch panel inspection apparatus according to claim 2, further comprising: a comparison unit that compares a voltage value; and an output unit that sends a switching signal to the switching unit. The touch panel inspection apparatus according to claim 1, wherein the threshold value is set to 49 to 51% of a power supply voltage. By applying a power supply voltage to a resistive film touch panel composed of a first resistive film having a pair of X-axis electrodes and a second resistive film having a pair of Y-axis electrodes, and measuring an output voltage value corresponding to a predetermined input position, In the touch panel inspection device for inspecting the electrical characteristics of the resistive touch panel,
A touch panel inspection apparatus comprising: potential compensation means for shifting an output voltage value detected from the predetermined input position to a high potential side by a predetermined amount. The touch panel inspection apparatus according to claim 6, wherein the potential compensation means includes a voltage dividing resistor inserted in series between the power supply voltage and the X-axis electrode or the Y-axis electrode. The touch panel inspection device according to claim 7, wherein a voltage dividing ratio of the resistor is 1/5 to 1/20.

Images