JP2011008715A - Coordinate input device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically correct a change in sensitivity of an input pen to stable sensitivity, when the surface resistance value of a surface resistor and the resistance value of a resistive peripheral electrode are changed due to temperature changes and secular changes caused by an environment and the time in which a coordinate input panel is used.SOLUTION: In a capacitively-coupled coordinate input device, a rectangular resistive peripheral electrode is formed to surround a surface resistor on the coordinate input panel, and driver units for creating a potential gradient with respect to the coordinate input panel are connected to the four apexes of the resistive peripheral electrode. A signal processing unit storing operation software calculates coordinates on the basis of position coordinate signals detected from an input pen. The driver unit has a function of controlling driving potential so that potential measured by a drive potential measuring means become constant. The signal processing unit varies a threshold value for determining whether or not the coordinate position signal of the input pen for designating coordinates is valid or invalid in accordance with the potential measured by the drive potential measuring means.

Description

  The present invention relates to a capacitively coupled coordinate input device that detects coordinates of a position where an input pen for coordinate indication comes into contact or approaches.

1 and 2 are a sectional view and a plan view showing an example of a capacitively coupled coordinate input panel. A capacitively coupled coordinate input panel 1 (hereinafter referred to as a coordinate input panel) is configured with a transparent insulating substrate 3 serving as a sensor portion as a center. A coordinate indicating input pen (hereinafter referred to as “input pen”) 9 is brought into contact with or close to the upper part of the transparent insulating base material 3 serving as an input surface, and the surface resistor 5 serving as a sensor portion under the transparent insulating base material 3. And the input pen 9 are capacitively coupled to detect coordinates. The transparent insulating substrate 3 is generally made of transparent glass or resin.
The sheet resistor 5 serving as the sensor portion is formed with a sheet resistor that is transparent and has a uniform sheet resistance value on the entire surface. The transparent surface resistor 5 is made of a transparent conductive material such as ITO (indium oxide) by sputtering or a tin oxide film by CVD.

  A resistive peripheral electrode 6 is formed on the transparent surface resistor 5. The resistive surrounding electrode 6 is formed by printing and baking in a desired pattern using, for example, conductive ink. Conductive solderable terminals 6A, 6B, 6C, 6D for connecting lead wires 7 (see FIG. 2) to the apexes of the resistive surrounding electrodes 6 as required. Ink may be printed and baked, or may be protected with insulating ink except for each apex.

A lead wire 7 is connected to lead wire connection terminal portions (hereinafter referred to as terminal portions) 6A, 6B, 6C, and 6D at each apex of the resistive surrounding electrode 6, and the lead wire 7 is connected to the signal processing portion 10. A potential gradient is sequentially formed from each direction in a portion of the surface resistor 5 surrounded by the resistive surrounding electrode 6.
Using the input pen 9 connected to the signal processing unit 10 by the cable 11, the potential at the position of the input pen 9 of the potential gradient formed on the coordinate input panel 1 is measured, and the potential is used. Calculate the coordinates.

  The signal processing unit 10 includes a detection circuit for measuring a potential signal from the input pen 9, a conversion circuit for digitizing the detected signal, a driver circuit for forming a potential gradient on the coordinate input panel 1, A CPU for converting the received signal into coordinate data, and its calculation software and storage device are included. {See JP 2001-43002 A (Patent Document 1)}

  The sum of the measured values of the potential at the position of the input pen 9 of the potential gradient formed on the coordinate input panel 1, that is, the total signal amount is between the input pen 9 and the surface resistor 5 arranged on the coordinate input panel 1. Varies with distance. This change is because the capacitive coupling changes depending on the distance between the surface resistor 5 and the input pen 9, and the closer the distance between the surface resistor 5 and the input pen 9 (input pen 9-1: FIG. 1). The potential measured through the input pen 9 increases, and the potential measured through the input pen 9 decreases as the distance between the surface resistor 5 and the input pen 9 increases (input pen 9-2). To do.

  When the total signal amount is small, the SN ratio is deteriorated and the position coordinates are not stable. Actually, the coordinates became unstable when the distance between the coordinate input panel 1 and the input pen 9 was about 10 cm. In general, in the capacitive coupling type input device, in order to solve the above-described problem, a threshold is set for the total amount of signals so that the distance between the coordinate input panel 1 and the input pen 9 is detected at, for example, 10 cm or less. If the total signal amount is larger than the threshold value, it is determined that the operator is inputting, and valid positional information of the input pen 9 is output. (Hereafter referred to as effective signal threshold)

  However, the reason why the total signal amount is reduced is not only the distance between the coordinate input panel 1 and the input pen 9. That is, the resistance value of the surface resistor 5 used in the coordinate input panel and the material used in the resistive surrounding electrode 6 changes depending on the temperature change of the environment in which it is used and the change over time when used for many years. Have nature.

  For example, when the combined resistance value of the surface resistor 5 and the resistive surrounding electrode 6 decreases, the drive formed in the lead wire connection terminal portions 6A, 6B, 6C, and 6D at each apex of the resistive surrounding electrode 6 The voltage is reduced, and the gradient of the potential gradient formed by the coordinate input panel 1 is reduced. As a result, when the total signal amount of the potential measured from the input pen 9 becomes smaller and becomes smaller than the set effective signal threshold, the operator inputs even if the distance between the surface resistor 5 and the input pen 9 is the same position. If the position value of the input pen 9 is not output and the combined resistance value increases, the gradient of the potential gradient formed on the coordinate input panel 1 increases, and the set effective value When the signal threshold value is exceeded, it is determined that the operator is inputting even if the distance between the coordinate input panel 1 and the input pen 9 is far, and the position information of the input pen is output. Accordingly, the effective distance between the coordinate input panel 1 and the input pen 9 becomes unstable due to a change in the combined resistance value of the surface resistor 5 and the resistive surrounding electrode 6. That is, if the effective signal threshold value is fixed, the effective distance between the coordinate input panel 1 and the input pen 9 changes, and there is a problem that the operability is deteriorated. (Hereinafter, an effective distance between the coordinate input panel 1 and the input pen 9 is referred to as input pen sensitivity.)

JP 2001-43002 A

The conventional capacitive coupling type input device can only be used in an environment where the input pen sensitivity is acceptable, and the resistance value obtained by combining the resistances of the surface resistor 5 and the resistive surrounding electrode 6 over time. When the change of the input pen sensitivity occurs, it is necessary to perform the sensitivity adjustment work again and reset the effective signal threshold.
The same problem is assumed even when the conventionally set composite resistance value cannot be ensured by changing the material and composition of the surface resistor 5 and the resistive surrounding electrode 6 used in the coordinate input panel.
An object of the present invention is that the surface resistance value of the surface resistor 5 and the resistance value of the resistive surrounding electrode 6 change due to a temperature change or a change with time which changes depending on the environment or time in which the coordinate input panel 1 is used. The purpose is to automatically correct the change in input pen sensitivity generated in step 1 to a stable input pen sensitivity.

  An electrostatic capacity coupling type coordinate input device for detecting coordinates of a position where an input pen for coordinate instruction comes into contact or approaches, wherein a surface resistor is provided on the coordinate input panel so as to surround the surface resistor. In order to measure the driving voltage of the driver unit, a square resistive peripheral electrode is formed, and a driver unit for forming a potential gradient with respect to the coordinate input panel is connected to the four apexes of the resistive peripheral electrode. A coordinate input device that calculates a coordinate by connecting a position coordinate signal detected from the coordinate pointing input pen by a signal processing unit that stores calculation software. A function of controlling the drive potential so that the potential measured by the drive potential measuring means is constant, and the signal processing unit corresponds to the potential measured by the drive potential measuring means, It proposes a coordinate input device characterized by capable of varying the threshold value for determining the validity / invalidity of the coordinate pointing input pen coordinate position signal.

As a result of using the coordinate input panel obtained in the present invention, even when the temperature of the environment at the time of use changes and the resistance value of the surface resistor and the resistive surrounding electrode changes, or it is used for a long time, the surface resistor Even when the resistance value of the resistive surrounding electrode has changed, it was possible to automatically correct the input pen sensitivity by measuring the drive drive voltage.

In addition, by setting the drive drive voltage to the original voltage, it was possible to correct the input pen sensitivity automatically and stably against noise.

Cross section of capacitively coupled coordinate input panel Plan view of capacitively coupled coordinate input panel Block diagram of the present invention Illustration of drive resistor

Hereinafter, embodiments according to the present invention will be described in detail with reference to the accompanying drawings.
FIG. 3 is a block diagram of a coordinate input device according to an embodiment of the present invention. Similar to the coordinate input panel 1 shown in FIG. 2, the coordinate input panel 1 is configured with a transparent insulating substrate 3 serving as a sensor portion as a center.
The lead wire 7 is connected to the lead wire connection terminal portions 6A, 6B, 6C, 6D at each apex of the resistive surrounding electrode 6, and the lead wire 7 is connected to the driver portion 20 and controlled from the signal processing portion 21. In accordance with the signal 33, a potential gradient is sequentially formed from the direction of each apex in the coordinate input region which is a portion of the surface resistor 5 surrounded by the resistive surrounding electrode 6. The input pen 9 is brought into contact with or brought close to the coordinate input panel 1 serving as an input surface, and capacitive coupling is performed between the input resistor 9 and the surface resistor 5 serving as a sensor portion under the transparent insulating base material 3, and the cable 11. To measure the potential at the position of the input pen 9 of the potential gradient formed on the coordinate input panel 1 connected to the signal processing unit 21, and calculate the coordinates using the potential.

In the drive unit 20, a potential gradient is formed by the changeover switch units 30 a to 30 d and the drive resistance units 31 a to 31 d connected to the lead wire 7. In the case of FIG. 3, an AC signal obtained by dividing the combined resistance value of the drive resistor 31a, the surrounding electrode 6, and the surface resistor 5 is applied to the 6A terminal, and the 6C terminal is connected to the ground, thereby connecting the 6A terminal and the 6C terminal. A linear potential gradient of the AC signal is formed between them.
A drive voltage lead line 34 connected between the changeover switch 30a and the drive resistor 31a measures the drive voltage by the signal processor 21. In FIG. 3, the drive voltage lead line 34 is connected to only one place, but may be connected to all four places between the changeover switch sections 30a to 30d and the resistance sections 31a to 31d.
The resistance values of the drive resistor units 31 a to 31 d can be varied by the control line 33 from the signal processing unit 21.

  The signal processing unit 21 includes a receiving circuit for measuring a potential signal from the input pen 9, a conversion circuit for digitizing the received signal, and a drive replacement control for forming a potential gradient in the coordinate input panel 1. , A drive voltage measuring circuit, a CPU for converting the received signal into coordinate data, and its calculation software / effective signal threshold variable control / storage device.

An example of the operation of the coordinate input device having the configuration shown in FIG. 3 will be described.
A potential gradient is applied to the coordinate panel 1. The potential gradient is given by switching the switches 30a to 30d provided in the drive unit 20, and the AC signal is connected to one of the terminals facing each other of the coordinate panel 1, the other is connected to the ground, and the other two sides are connected. Leave nothing connected. FIG. 3 shows a state in which an AC signal is connected to the switch 30a, 30c is connected to the ground, and nothing is connected to 30b and 30d, and the potential gradient decreases linearly from the terminal portion 6A to 6C. . At this time, the drive voltage is measured and stored in the signal processing unit 21 from the drive voltage lead-out line 34 for the potential of the terminal unit 6A.

Next, an AC signal is connected to the switch 30c, 30a is connected to the ground, and nothing is connected to 30b and 30d. Next, an AC signal is connected to the switch 30b, 30d is connected to the ground, and nothing is connected to 30a and 30c. Next, an AC signal is connected to the switch 30d, 30b is connected to the ground, and nothing is connected to 30a and 30c. The switching operations are sequentially performed.
The measurement of the drive voltage may store one location of the terminal portion 6A, but if the drive voltage of the other terminals 6B to 6D is measured and stored, the setting accuracy of the effective threshold described later is further improved.

  When the input pen 9 abuts or approaches the coordinate panel 1 with the terminal potential gradients 6A to 6D on the coordinate panel 1 applied, the potentials from 6A to 6B corresponding to the position of the input pen 9 on the coordinate panel 1 Can be measured.

  When the drive voltage at the time of design or production is 10 V and the distance between the coordinate input panel 1 and the input pen 9 is 10 cm, the measured value of the potential at the position of the input pen 9 of the potential gradient formed on the coordinate input panel 1 If the total, that is, the total signal amount is 100, the effective signal threshold is set to 100, and the signal total amount below that is invalid. That is, the coordinate detection is effective for up to 10 cm between the coordinate input panel 1 and the input pen 9. (For the sake of explanation, the total signal amount is assumed to be 100.)

  When the combined resistance value of the surface resistor 5 and the resistive surrounding electrode 6 is reduced and the drive voltage is reduced to 9V, the effective signal threshold is also reset from 100 at design to 90 at the same ratio. The sensitivity of the input pen 9 is set to be the same as that at the time of design, and is valid until the distance between the coordinate input panel 1 and the input pen 9 is 10 cm.

  If the resistance values on one side of the peripheral electrode 6 are all the same, it is sufficient to measure the drive voltage at one location. However, if resistance changes on all four sides are assumed, measure the drive voltage at four locations and correspond to the voltage average value. If the effective signal threshold is set, the sensitivity of the input pen 9 can be set with higher accuracy.

  When the drive voltage drops from 10V to 5V, the effective signal threshold may be set to 50 correspondingly. However, when the drive voltage becomes less than half, the potential detected from the input pen 9 decreases in proportion to the drive voltage. The ratio cannot be ignored, that is, the coordinate position accuracy becomes worse. Since the drive voltage becomes a potential obtained by dividing the combined resistance value of the surface resistor 5 and the resistive surrounding electrode 6 and the drive resistor portions 31a to 31d, the resistance values of the drive resistor portions 31a to 31d are used in this case. The drive voltage can be increased by lowering.

For example, when the combined resistance value of the surface resistor 5 and the resistive surrounding electrode 6 changes from 1 KΩ to 500Ω, the original drive voltage is obtained when the drive resistance is changed from 500Ω to 250Ω.
In addition, since the drive voltage for confirmation can be measured, an effective signal threshold corresponding to the measured value can be set.

FIG. 4 shows an example of the drive resistor units 31a to 31d. When the control line 36-1 is turned on, the transistor 35-1 drives the coordinate input panel via the resistor 37-1. When the control lines 35-1 and 35-2 are turned on, the combined resistance of the resistors 37-1 and 37-2 becomes the lowest resistance, and the drive voltage is maximized. In the circuit of the embodiment, three types of resistance values can be switched. Therefore, it becomes possible to set the drive voltage in three stages.
The present invention is not limited to the above embodiments, and includes various coordinate threshold setting and drive voltage switching conditions within the technical scope of the present invention.

Even when the temperature of the environment during use changes and the resistance value of the surface resistor and the resistive surrounding electrode changes, or after long-term use, the resistance value of the surface resistor and the resistive surrounding electrode changes. Even in this case, it was possible to correct the input pen sensitivity automatically and stably by measuring the drive drive voltage. Further, by setting the drive drive voltage to the original voltage, it is possible to realize a coordinate input device capable of correcting the input pen sensitivity to be automatically and stable resistant to noise.

DESCRIPTION OF SYMBOLS 1 Capacitive coupling type coordinate input panel 3 Transparent insulating base material 5 Surface resistor 6 Resistive surrounding electrode 6A Lead wire connection terminal part 6B Lead wire connection terminal part 6C Lead wire connection terminal part 6D Lead wire connection use Terminal unit 7 Lead line 9 Coordinate instruction input pen 9-1 Coordinate instruction input pen is in contact with coordinate input panel 9-2 Coordinate instruction input pen is separated from coordinate input panel 10 Signal processing unit 11 Input Pen cable 20 Drive unit 21 Signal processing unit 30a-30d Changeover switch unit 31a-31d Drive resistor unit 33 Control signal 34 Drive voltage lead-out line 35-1, 35-2 Transistor 36-1, 36-2 Drive resistance control line 37 -1, 37-2 Resistor

Claims (1)

  An electrostatic capacity coupling type coordinate input device for detecting coordinates of a position where an input pen for coordinate instruction comes into contact or approaches, wherein a surface resistor is provided on the coordinate input panel so as to surround the surface resistor. In order to measure the driving voltage of the driver unit, a square resistive peripheral electrode is formed, and a driver unit for forming a potential gradient with respect to the coordinate input panel is connected to the four apexes of the resistive peripheral electrode. A coordinate input device that calculates a coordinate by connecting a position coordinate signal detected from the coordinate pointing input pen by a signal processing unit that stores calculation software. A function of controlling the drive potential so that the potential measured by the drive potential measuring means is constant, and the signal processing unit corresponds to the potential measured by the drive potential measuring means, Coordinate input apparatus characterized by varying the threshold value for determining the validity / invalidity of the coordinate pointing input pen coordinate position signal.