JP2000250710A - Touch panel device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide high reliability by excluding erroneous data caused by erroneous input operation at the time of plural point touches and continuous inputs by setting a touch position invalid when the coordinate of that touch position is changed from a set value within fixed time. SOLUTION: In order to measure a coordinate change quantity per unit time, a timer circuit provided in a control part is started. When current values at four corners of a sensor panel are greater than specified values, it is judged a finger touches the surface of the sensor panel, the timer circuit is stopped and time to the signal detection is stored in a memory provided in the control part (S1-S4). A difference from the last coordinate value is calculated as a coordinate change quantity per unit time and the coordinate value of this time is stored in the memory for calculating the next coordinate change quantity (S5). The set value is compared with the coordinate change quantity and when the quantity is smaller than the set value, the coordinate is determined. Then, a coordinate code is outputted to an external device. When the quantity is greater than the set value, it is judged the surface of the panel is touched with any conductor such as palm excepting for the finger instructed by an operator and the coordinate of this time is judged invalid to perform the other processing (S6).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a touch panel device for detecting a touch state of a finger on a panel, and more particularly to a direct contact type and a finger in which a finger or a conductive object directly and electrically contacts a conductive surface of a sensor panel. Alternatively, the present invention relates to a capacitive coupling type touch panel device that detects capacitance between a conductor and a sensor panel.

[0002]

2. Description of the Related Art As a typical touch panel, there is a touch panel type (hereinafter, referred to as a resistive film type) using a panel having a structure in which two resistive films opposed to each other are electrically connected to each other at a pressing point. The above touch point calculation method of the touch panel is such that a constant voltage is applied to one electrode of the upper resistive film, the other electrode is grounded, and a voltage value is detected at the press point via the lower resistive film to obtain X (Y). Calculate the axial coordinate values. Also,
Japanese Patent Application No. Hei 10-199636 filed by the present applicant has been proposed.

[0003]

In the case of the resistive film method, when the operator touches the touch panel surface at a plurality of points by mistake, for example, when the operator touches the touch panel at two places of the fingertip and the palm, the fingertip position is determined. One average point of the palm position is calculated, and the input position shifts from the point at which the operator is conscious, causing an erroneous input.

In an input device provided with means for recognizing and avoiding the case of contact at a plurality of points, a sensor panel for detecting a touch state of a finger on a panel has sensor conductors arranged in a grid in the X and Y directions. However, the panel structure becomes complicated and the cost is increased.

[0005]

SUMMARY OF THE INVENTION The present invention is an apparatus for detecting a touch position of a finger or a conductor on a sensor panel surface, wherein the sensor panel is formed of a resistive film material uniformly and has a peripheral portion. A surrounding peripheral resistive electrode is provided, connected to a signal processing unit that holds the input voltage at the four vertices of the peripheral electrode, and the contact position of a finger or a conductor on the panel surface is determined from the current value flowing through the four vertices. The present invention proposes a touch panel device for calculating, which includes means for determining that the contact position is invalid if the coordinates of the contact position change from a set value within a predetermined time.

[0006]

In the touch panel device according to the present invention, if the coordinate data of the contact position changes from the set value within a predetermined time, it is determined that there are a plurality of contact points on the sensor panel surface of the operator, and invalidity is determined. If the amount of change in the detected current value at the four vertices of the surrounding electrodes is equal to or larger than the set value, it is determined that the contact position is invalid, so that continuous input such as character input or drawing and contact at a plurality of locations can be determined.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION A sensor panel is formed by uniformly forming a resistive film material on the surface of a base resin or glass.
A resistive peripheral electrode surrounding the periphery of the resistive film is provided, is electrically connected to the four vertices of the peripheral electrode, and flows to the four vertices in an electric circuit that holds an input voltage from the four vertices of the peripheral electrode. The touch panel device calculates a contact position of a finger or a conductive material on the panel surface from a current value.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an explanatory diagram of a direct contact type touch panel device that detects a contact position (X, Y coordinates) of a finger 7 on a surface of a sensor panel 3. The sensor panel 3 has a low resistance peripheral electrode 6 closely mounted around a uniform sheet resistor 5. One lead wire (shield wire) 10 is connected to each of the four corners (points A, B, C, and D). There is no insulating layer on the surface of the uniform surface resistor 5, and the finger 7 directly electrically contacts the surface resistor 5. The detailed structure of the sensor panel 3 will be described later. Although the shield plate 4 is not always necessary, when the sensor panel 3 is arranged in front of a display surface of a CRT display or a liquid crystal display device or the like, it is effective to eliminate unnecessary electromagnetic radiation.

Each connection terminal of the signal processing section 11 with the sensor panel 3 has a low impedance with respect to the voltage floating system reference potential circuit 16, so that the entire sensor panel 3 (including the shield plate 4) has a low voltage. Floating system reference potential circuit 1
6 follows the potential. The signal processing unit 11 is powered by an isolation power supply 13 supplied from a battery belonging to the voltage floating system 1 or a non-floating system. The transfer of analog or digital electrical information between the voltage floating system 1 and the non-floating system 2 is performed via an isolator 12. Interface 1 that belongs to non-floating system 2 for part of signal processing
8 may be performed.

Next, the operation for detecting the position (X, Y coordinates) of the finger 7 on the sensor panel 3 will be described. AC signal generator 14 is 460 kHz 0.4 Vrm
Generate a s sine wave. The AC signal coupling capacitor 15 has 2200 pF, and the impedance value for 460 kHz is 160Ω, which is a sufficiently low impedance value for AC signal coupling. The sensor panel 3 is connected to the voltage floating system reference potential circuit 16 as described above.
Follow the potential. Uniform sheet resistor 5 of sensor panel 3
And the finger 7 make direct contact. The human body is a conductor having a resistance of about several kΩ to 10 kΩ, and is represented by reference numeral 8 as an equivalent resistance.

The current loop of the coordinate detection AC signal is as follows. AC signal generator 14, voltage floating system reference potential circuit 16, low input impedance circuit of signal processing unit 11, shielded wire 10, low resistance surrounding electrode 6, uniform surface resistor 5, finger 7, human body equivalent resistance 8 Ground effect impedance 9 (Z1) of the human body, ground 21, non-floating ground impedance 20 (Z2), coupled equivalent voltage source 19 from AC power supply, non-floating ground circuit 17, AC signal coupling capacitor 15, and Original AC signal generator 14
Return to

Although the structure of the sensor panel 3 is not shown,
The sensor panel 3 is obtained by fixing glass particles 31 to a transparent glass surface etched with hydrofluoric acid.
In each case, the surface is roughened and subjected to an anti-glare treatment of several thousand angstroms, and a resistor 32 such as tin oxide (Sn02) or indium tin oxide (ITO) is uniformly formed two-dimensionally (in any direction) thereon. It is formed to have a resistance value. Since the thickness of the resistor film at this time is about several hundred angstroms, it can be formed sufficiently uniformly on the glass surface which has been subjected to the antiglare treatment.

In this embodiment, the resistance film of the sensor panel 3 is formed by spraying a tin oxide (SnO 2) film on a glass surface. However, if the opaque type is acceptable, another manufacturing method such as carbon paste printing is used. May be formed. The sheet resistance is about 1 kΩ / □. Around the outer periphery, a peripheral electrode 6 was made of carbon (or silver carbon) as a material and arranged closely. The resistance value of the surrounding electrode 6 is about 120Ω between both ends of each side.
And Various shapes of the peripheral electrode 6 have been proposed, and in this embodiment, the peripheral electrode 6 has a simple linear shape. Surrounding electrode 6
A lead wire 10 (shielded wire) is connected to each apex.

The sheet resistor 5 has a uniform resistance value distribution, and the AC signal current flowing through the finger 7 flows more to the connection points (points A, B, C, and D) closer to the direct contact point. .
Therefore, the contact point (X, Y coordinates) of the finger 7 on the sensor panel 3 is calculated from the ratio of the AC signal current values flowing through the four terminals of the signal processing unit 11.

A flowing through each of the four terminals of the signal processing unit 11
From the ratio of the C signal current value, the contact point of the finger 7 on the sensor panel 3 (X, Y coordinates) calculation formula for calculating the is _{X = (i B + i C} -i A -i D) / (i A + i B + I _C +
_{i D) Y = (i C} + i D -i A -i B) / (i A + i B + i C +
i _D ). Here, i _A , i _B , i _C , i _D are 4
It is a current value flowing from the top, that is, each top in the clockwise direction from the upper left of the panel.

Actually, there is a contact resistance between the finger 7 and the sensor panel. When the finger is a finger, the contact resistance is substantially proportional to the contact area, and the AC signal current flowing through the four terminals is substantially proportional to the contact area. However, the above-described coordinate calculation formula can calculate the contact point without being affected by the magnitude of the AC signal current flowing through the sensor panel 3.

Here, if another finger, palm, or a person other than the operator touches the panel surface at a point other than the finger conscious of the operator, the current flowing through the four terminals changes. The result will change greatly. That is, when the coordinate calculation result changes suddenly, it can be estimated that the conductor other than the conscious finger is in contact with the panel surface.

When the operator performs continuous input operations such as character input and drawing, the coordinate value changes with the movement of the finger. It is difficult to determine the invalidity. During the operation of such continuous input by the operator, the total area of the currents flowing through the four terminals of the signal processing unit 11 does not change much because the contact area of the finger is constant to some extent. That is, when the sum of the current values flowing at each vertex changes suddenly, it can be estimated that the conductor other than the conscious finger is in contact with the panel surface.

Next, the operation sequence of the control unit until the finger contact position is detected will be described. FIG. 2 is a flowchart for invalidating a plurality of contact positions according to the first embodiment of the present invention. In step S1, a timer circuit included in the control unit is started to measure a coordinate change amount per unit time. In steps S2 and S3, if the current values at points A, B, C and D are equal to or less than the predetermined values, it is determined that the finger is not in contact with the sensor panel surface, and the process returns to step S1 to restart the timer circuit. In step S4, the timer circuit is stopped, and the time until signal detection is stored in a memory included in the control unit.
In step S5, the difference from the previous coordinate value is calculated as a coordinate change amount per unit time. In S6, the current coordinate value is stored in the memory for calculating the next coordinate change amount. In step S7, the set value is compared with the coordinate change amount. If the set value is smaller than the set value, the coordinates are determined and a coordinate code is output to an external device. It is determined that a conductor such as has touched the panel surface, and the current coordinates are invalidated and another process is performed.

FIG. 3 is a flowchart for invalidating a plurality of contact positions according to the second embodiment of the present invention. In order to measure the amount of coordinate change per unit time in step S1,
The timer circuit included in the control unit is started. In steps S2 and S3, if the current values at points A, B, C and D are equal to or less than the predetermined values, it is determined that the finger is not in contact with the sensor panel surface, and the process returns to step S1 to restart the timer circuit. In step S4, the timer circuit is stopped, and the time until signal detection is stored in a memory included in the control unit.
In step 5, the difference between the current value at the previous point A, B, C, and D and the current change amount per unit time are calculated. In S6, the current value of this time is stored in the memory for calculating the next current change amount. In step S7, the set value is compared with the current change amount. If the set value is smaller than the set value, the coordinates are determined and a coordinate code is output to an external device. If the set value is larger than the set value, the palm or another finger other than the finger specified by the operator is used. It is determined that a conductor such as has touched the panel surface, and the current coordinates are invalidated and another process is performed.

As described above, the first embodiment is particularly effective for a touch panel device for inputting an item, in which a finger designates one section of a panel such as a touch keyboard. The second embodiment is applicable to a touch panel device. This is particularly effective for a touch panel device for continuous input such as character input and drawing. Of course, by selectively using the above-described invalidity determination depending on the purpose of use and necessity, a highly reliable touch panel device with better operability can be realized.

[0022]

As described above, the present invention has the above-described structure. Therefore, despite the simple structure of the sensor panel, it is possible to prevent the operator from touching the sensor panel at multiple points and erroneous input operation during continuous input. Erroneous data was eliminated and a highly reliable touch panel device was obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a direct contact type touch panel device for detecting a contact position of a finger;

FIG. 2 is a flowchart for invalidating a plurality of contact positions according to the first embodiment of the present invention;

FIG. 3 is a flowchart for invalidating a plurality of contact positions according to a second embodiment of the present invention;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Voltage floating system 2 Non-floating system 3 Sensor panel 4 Shield plate 5 Uniform surface resistor 6 Low resistance surrounding electrode 7 Finger 8 Human equivalent resistance 9 Human body grounding effect impedance 10 Shielded wire 11 Signal processing unit 12 Isolator 13 Battery Or an isolation power supply supplied from a non-floating system 14 AC signal generator 15 AC signal coupling capacitor (insulating capacitor for AC power supply component) 16 voltage floating system reference potential circuit 17 non-floating system ground circuit 18 interface 19 AC power supply Coupled equivalent voltage source 20 non-floating ground impedance 21 ground

Claims (2)

[Claims] An apparatus for detecting a touch position of a finger or a conductor on a sensor panel surface, wherein the sensor panel is formed of a resistive film material uniformly and has a resistive peripheral electrode surrounding the periphery. The touch panel device is connected to a signal processing unit that holds input voltages at the four vertices of the peripheral electrode and calculates a contact position of a finger or a conductor on the panel surface from a current value flowing through the four vertices. A touch panel device comprising: means for determining that the contact position is invalid when the coordinates of the contact position change from a set value. 2. An apparatus for detecting a touch position of a finger or a conductor on a sensor panel surface, wherein the sensor panel is formed of a resistive material uniformly and has a resistive peripheral electrode surrounding the periphery. A touch panel device that is connected to a signal processing unit that holds input voltages at four vertices of the peripheral electrode and calculates a contact position of a finger or a conductor on the panel surface from a current value flowing through the four vertices; 2. The touch panel device according to claim 1, further comprising: means for determining that the contact position is invalid when the amount of change in the detected current value at the four vertices of the electrode is equal to or greater than a set value.