JP4006872B2 - Touch panel device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a touch panel device that detects a touch state of a finger panel, and more particularly, a direct contact type in which a finger or a conductor directly contacts a conductive surface of a sensor panel and a finger or conductor and a sensor panel. The present invention relates to a capacitive coupling type touch panel device that detects a capacitance between them.
[0002]
[Prior art]
As a typical touch panel, there is a method using a panel having a structure in which two layers of resistance films facing inside are connected to each other at a pressing point (hereinafter referred to as a resistance film method). In the touch point calculation method of the touch panel, a constant voltage is applied to one electrode of the upper resistive film, the other electrode is grounded, and the voltage value is detected via the lower resistive film at the pressed point. X (Y) Axial coordinate values are calculated. Also, Japanese Patent Application No. 10-199636, which is an application of the present applicant, has been proposed.
[0003]
[Problems to be solved by the invention]
In the conventional technique described above, in the case of the resistive film method, when the operator touches multiple points on the touch panel surface accidentally, for example, when touching the two touch panels of the fingertip and the palm, one point averaged between the fingertip position and the palm position is calculated. As a result, the input position deviates from the point that the operator is conscious of, causing erroneous input.
[0004]
In addition, in an input device provided with means for recognizing and avoiding a case where a plurality of points touch each other, the sensor panel for detecting the touch state of the finger panel has sensor conductors arranged in a grid in the X and Y directions. The panel structure was complicated and the cost was increased.
[0005]
[Means for Solving the Problems]
An apparatus for detecting a touch position of a finger or a conductor on a sensor panel surface, the apparatus detecting a touch position of a finger or a conductor on a sensor panel surface, wherein the sensor panel is a resistive film. Resistive peripheral electrodes are formed uniformly, and are connected to an electric circuit that holds the four apex input voltages of the peripheral electrodes, and the current value flowing at the four apexes is determined on the panel surface. A touch panel device for calculating a contact position of a finger or a conductive material, wherein when the coordinates of the contact position change from a set value within a predetermined time, a means for determining that the contact position is invalid , A touch panel device including means for determining that the contact position is invalid when the total change amount of the detected current values at the four vertices within a predetermined time is equal to or greater than a set value is proposed.
[0006]
[Action]
In the touch panel device of the present invention, when 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 determination is performed. Further, if the amount of change in the detected current value at the four vertices of the surrounding electrodes is equal to or greater than a set value, it is possible to determine continuous input such as character input or drawing and contact at multiple points by determining that the contact position is invalid.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
In the sensor panel, a resistive film material is uniformly formed on the surface of a base resin, glass or the like, and a resistive surrounding electrode surrounding the periphery of the resistive film is disposed, and electrically connected to the four apexes of the surrounding electrode. This is an electric circuit that is connected and holds an input voltage from the four vertices of the surrounding electrode, and is a touch panel device that calculates a contact position of a finger or a conductive material on the panel surface from a current value flowing through the four vertices.
[0008]
【Example】
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 touch panel device that detects a contact position (X, Y coordinates) of the finger 7 on the surface of the sensor panel 3. In the sensor panel 3, a low resistance peripheral electrode 6 is disposed in close contact with a uniform surface resistor 5. One lead wire (shield wire) 10 is connected to each of the four corners (points A, B, C, D). There is no insulating layer on the surface of the uniform surface resistor 5, and the finger 7 is in direct electrical contact with 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 the display surface of a CRT display or a liquid crystal display device or the like, it is effective in preventing unnecessary electromagnetic radiation.
[0009]
Each connection terminal of the signal processing unit 11 to the sensor panel 3 has a low impedance with respect to the voltage floating system reference potential circuit 16, and therefore the entire sensor panel 3 (including the shield plate 4) is a voltage floating system reference. The potential follows the potential circuit 16. 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. Analog or digital electrical information is exchanged between the voltage floating system 1 and the non-floating system 2 via an isolator 12. A part of the signal processing may be performed in the interface 18 belonging to the non-floating system 2.
[0010]
Next, the operation when detecting the position (X, Y coordinates) of the finger 7 on the sensor panel 3 will be described. The AC signal generator 14 generates a sine wave of 460 kHz 0.4 Vrms. The AC signal coupling capacitor 15 is 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 follows the voltage floating system reference potential circuit 16 as described above. The uniform sheet resistor 5 and the finger 7 of the sensor panel 3 are in direct contact. The human body is a conductor having a resistance of about several kΩ to 10 kΩ, and is denoted by reference numeral 8 as an equivalent resistance.
[0011]
The current loop of the AC signal for coordinate detection 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 peripheral 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 system ground impedance 20 (Z2), coupled equivalent voltage source 19 from AC power source, non-floating system ground circuit 17, AC signal coupling capacitor 15, and Return to the original AC signal generator 14.
[0012]
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, both of which roughen the surface and have an anti-glare treatment of several thousand angstroms. Then, a resistor 32 such as tin oxide (Sn02) or indium tin oxide (ITO) is formed thereon so as to have a uniform resistance value in two dimensions (in any direction). Since the thickness of the resistor film at this time is about several hundreds of angstroms, it can be formed evenly even on the antiglare-treated glass surface.
[0013]
In this embodiment, the resistance film of the sensor panel 3 is a tin oxide (SnO2) film formed on the glass surface by spraying. However, if the opaque type is acceptable, it may be formed by another manufacturing method such as carbon paste printing. May be. The sheet resistance value is about 1 kΩ / □. The peripheral electrode 6 was closely attached to the outer periphery using carbon (or silver carbon) as a material. The resistance value of the surrounding electrode 6 was about 120Ω between both ends of each side. Various shapes of the peripheral electrode 6 have been proposed, and a simple straight line is used in this embodiment. A lead wire 10 (shield wire) is connected to each vertex of the surrounding electrode 6.
[0014]
The surface resistor 5 has a uniform resistance value distribution, and the AC signal current flowing through the finger 7 flows more at connection points (points A, B, C, and D) closer to the direct contact point. Therefore, the contact point (X, Y coordinate) 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.
[0015]
The calculation formula for calculating the contact point (X, Y coordinate) of the finger 7 on the sensor panel 3 from the ratio of the AC signal current values flowing through the four terminals of the signal processing unit 11 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)
Normalized by. Here, i _A , i _B , i _C , and i _D are current values that flow from the four apexes, that is, the apexes in the clockwise direction from the upper left of the panel.
[0016]
Actually, there is a contact resistance between the finger 7 and the sensor panel. In the case of the finger, the contact resistance is approximately proportional to the contact area, and the AC signal current flowing through the four terminals is approximately proportional to the contact area. However, in the coordinate calculation formula, the contact point can be calculated without being affected by the magnitude of the AC signal current flowing through the sensor panel 3.
[0017]
Here, when a finger other than the finger conscious of the operator or the palm of the hand or a person other than the operator touches the panel surface, the current flowing through the four terminals changes, so the result of the coordinate calculation formula is large. It will change. That is, when the coordinate calculation result changes suddenly, it can be estimated that a conductor other than the conscious finger is in contact with the panel surface.
[0018]
In addition, when the operator performs input operations such as character input and drawing continuously, the coordinate value changes with the movement of the finger, so the change amount of the coordinate determines the invalidity when a conductor other than the conscious is in contact with the panel surface Becomes difficult. Since the contact area of the finger is constant to some extent during the operation of continuous input by such an operator, the total value of the current flowing through the four terminals of the signal processing unit 11 does not change much. That is, when the sum of the current values flowing through the vertices suddenly changes, it can be estimated that a conductor other than the conscious finger is in contact with the panel surface.
[0019]
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 in order 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 touching 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 the next coordinate change amount calculation. In step S7, the set value is compared with the coordinate change amount. If the set value is smaller than the set value, the coordinate is determined and the coordinate code is output to the external device. It is determined that a conductor object such as has come into contact with the panel surface, and the current coordinate is invalidated and another process is performed.
[0020]
FIG. 3 is a flowchart for invalidating a plurality of contact positions according to the second embodiment of the present invention. In step S1, a timer circuit included in the control unit is started in order 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 touching 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 current values at the previous points A, B, C, and D is determined as unit time. The amount of current change per hit is calculated. In S6, the current value of this time is stored in the memory for calculation of the next current change amount. In step S7, the set value is compared with the amount of current change. If it is smaller than the set value, the coordinates are determined and a coordinate code is output to the external device. If it is greater than the set value, the palm or other fingers other than the finger indicated by the operator are used. It is determined that a conductor object such as has come into contact with the panel surface, and the current coordinate is invalidated and another process is performed.
[0021]
As described above, the first embodiment is particularly effective for a touch panel device for inputting items, in which a finger is used to designate a section of a panel such as a touch keyboard, and the second embodiment is used for character input or This is particularly effective for a touch panel device intended for continuous input such as drawing. Of course, by using the above-mentioned invalidity determination properly according to the purpose of use and necessity, it is possible to realize a highly reliable touch panel device with better operability.
[0022]
【The invention's effect】
Since the present invention is configured as described above, it eliminates erroneous data due to an incorrect input operation at the time of continuous input and multiple points of contact with the operator's sensor panel despite the fact that the structure of the sensor panel is simple. 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 that detects a finger contact position. FIG. 2 is a flowchart for invalidating a plurality of contact positions according to a first embodiment of the present invention. Flowchart for invalidating multiple contact positions in the embodiment [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 body equivalent resistance 9 Ground effect impedance 10 Human shield 11 Electric signal 11 Signal processor 12 Isolator 13 Battery Or the isolation power supply 14 supplied from the non-floating system AC signal generator 15 AC signal coupling capacitor (insulation capacitor for AC power supply component)
16 Voltage floating system reference potential circuit 17 Non-floating system ground circuit 18 Interface 19 Coupling equivalent voltage source 20 from AC power source 20 Non-floating system ground impedance 21 Ground

Claims (1)

An apparatus for detecting a touch position of a finger or a conductive material on a sensor panel surface, wherein the sensor panel is formed of a resistive film material uniformly and is provided with a resistive peripheral electrode surrounding the periphery. A touch panel device that is connected to an electric circuit that holds an input voltage at four vertices of an 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. If the coordinates of the change from the set value, the means for determining that the contact position is invalid, and at the time of continuous input, if the total change amount within a certain time of the detected current value of the four vertices of the surrounding electrode is greater than or equal to the set value, A touch panel device comprising: means for determining that the contact position is invalid.

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