JP3977577B2 - Touch panel device - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
The present invention relates to a touch panel device, and more particularly to a touch panel device suitable for use in a resistive film type.
[0002]
[Prior art]
2. Description of the Related Art In recent years, touch panel devices have become widespread as input devices that are used over a display device (for example, a liquid crystal display device). Since the touch panel device can display various operation buttons and the like by changing the image displayed on the display device, for example, in an in-vehicle audio device, a plurality of devices such as a CD player, a CD changer, and an MD player are provided. It is used as an input device for centralized operation. And in this touch panel device, there is a touch panel device using a resistive film type touch panel.
[0003]
First, the configuration and operation principle of a resistive film type touch panel (hereinafter simply referred to as a touch panel) will be described. As shown in FIG. 5, the touch panel includes resistance films 43 and 44 having electrodes 41 and 42 disposed on one surface, respectively, and a spacer 45, and the spacer 45 is formed between the other surfaces of the resistance films 43 and 44. It has a configuration in which it is sandwiched. As shown in FIG. 6, the electrode 41 disposed on one surface of the resistance film 43 includes a pair of electrodes 41 a and 41 b and is disposed so as to be parallel to the X axis. The electrodes 41a and 41b are connected to panel terminals U and D (hereinafter referred to as U terminal and D terminal, respectively). Similarly, the electrode 42 disposed on one surface of the resistance film 44 includes a pair of electrodes 42a and 42b, and is disposed to face each other so as to be parallel to the Y axis. The electrodes 42a and 42b are connected to panel terminals R and L (hereinafter referred to as R terminal and L terminal, respectively). When the user presses the other surface of the resistance film 43 with a finger or a pen, the other surfaces of the resistance films 43 and 44 come into contact with each other.
[0004]
When reading the X coordinate of the pressed point from the touch panel, a voltage of 5 V is applied to the R terminal, the L terminal is grounded, and the U terminal and the D terminal are opened. Then, by connecting an A / D converter (not shown) to the D terminal and A / D converting the voltage at the D terminal, the data of the X coordinate can be read. Similarly, when reading the Y coordinate, a voltage of 5 V is applied to the U terminal, the D terminal is grounded, and the R and L terminals are opened. The Y coordinate can be read by connecting an A / D converter to the L terminal and A / D converting the voltage at the L terminal.
[0005]
Here, as shown in FIG. 7, if the point A (x1, y1) on the touch panel is pressed with a finger or a pen, the touch panel is as shown in FIG. Can be schematically represented. Note that X and Y are the lengths of the touch panel in the X-axis and Y-axis directions, respectively, and x1 and y1 are the coordinates of the pressed points, respectively. In FIG. 8, 51 is the pressing point A, 52 is the resistance R ₁ of the resistance film between the pressing point A and the U terminal, and 53 is the resistance R ₂ of the resistance film between the pressing point A and the D terminal. Each is shown. Here, when a voltage of 5 V is applied to the U terminal and the voltage of the L terminal when the D terminal is grounded is V _L , the voltage V _{L of the} L terminal can be expressed by the following equation.
V _L = R ₂ V ₀ / (R ₁ + R ₂ ) = R ₂ V ₀ / R _ud (1)
(R _ud : Resistance of resistance film between U terminal and D terminal)
Here, if the resistance of the resistance film is uniform,
R ₂ / R _ud = y ₁ / Y (2)
Therefore, V _{L in} equation (1) can represent the coordinate of the pressing point A in the Y-axis direction. That is, substituting equation (2) into equation (1) above,
y ₁ = Y · V _L / V ₀ (3)
It becomes.
[0006]
Similarly, when obtaining the X coordinate, if a voltage of 5 V is applied to the R terminal and the voltage of the D terminal when the L terminal is grounded is V _D , then V _D is
x1 = X · V _D / V ₀
Thus, the coordinates in the X-axis direction can be expressed.
[0007]
FIG. 9 is a configuration diagram of a conventional touch panel device including a resistive film type touch panel. In FIG. 9, reference numeral 71 denotes a touch panel, 72 denotes an electrode state setting unit, 73 denotes a microcomputer unit, and 74 denotes a pull-down unit.
[0008]
The electrode state setting unit 72 is for controlling the state of each panel terminal U, D, R, L of the touch panel 71, and includes transistors 72a to 72e. A voltage of 5 V is applied to the electrode state setting unit 72 from the outside via the terminal 75, and a predetermined control voltage is applied from the microcomputer unit 73.
[0009]
The microcomputer unit 73 controls the electrode state setting unit 72 to detect the coordinates of the pressed point, and includes SEL1 to SEL3 terminals, an X terminal, and a Y terminal. Although not particularly shown, the microcomputer unit 73 has an A / D converter and is connected to the X terminal and the Y terminal. The pull-down unit 74 is for pulling down a terminal for detecting coordinates (hereinafter referred to as a coordinate detection terminal) among the panel terminals of the touch panel 71 and has two resistors.
[0010]
And the microcomputer part 73 changes the control voltage applied to the electrode state setting part 72 from SEL1-SEL3 when detecting the coordinate of a pressing point, as shown in the table | surface of FIG. For example, when detecting the X coordinate, 5 V (H) is applied from SEL2, and SEL1 and SEL3 are set to 0 V (L). Then, the U and D terminals of the touch panel 71 are opened, the R terminal is 5 V, and the L terminal is grounded. Then, the microcomputer unit 73 detects the X coordinate of the pressed point from the voltage detected at the X terminal.
[0011]
Similarly, when detecting the Y coordinate, the microcomputer unit 73 applies a voltage of 5 V (H) from SEL1 and SEL3, and sets SEL2 to 0 V (L). Then, the R and L terminals of the touch panel 71 are opened, a voltage of 5 V is applied to the U terminal, and the D terminal is grounded. Then, the microcomputer unit 73 detects the Y coordinate of the pressed point from the voltage detected at the Y terminal.
[0012]
Then, the microcomputer unit 73 outputs a predetermined control signal associated with the area including the coordinates of the detected pressing point to various devices (not shown) connected to the microcomputer unit 73 and is connected. Various devices are controlled.
[0013]
[Problems to be solved by the invention]
By the way, due to the structure of the touch panel, the contact surface between the upper electrode and the lower electrode may become extremely small due to the contact pressure pressed with a finger or a pen. For example, when the contact pressure to be pressed is large, as shown in FIG. 11A, the contact surface becomes wider and the contact resistance becomes smaller. Further, when the contact pressure to be pressed is small, as shown in FIG. 11B, the contact area becomes small and the contact resistance becomes large.
[0014]
FIG. 12 shows an equivalent circuit diagram when the touch panel is pressed. In the figure, 76 and 77 are resistances R ₁ and R ₂ of the resistance film between the pressing point and the electrode, 78 is a contact resistance R ₃ , 79 is a resistance of the pull-down portion 74, 80 is a voltage supply terminal, 81 is A / D ports are shown respectively. R ₁ + R ₂ is several hundred Ω, R ₃ is several hundred Ω when the contact resistance is large, and R ₄ is several tens kΩ.
[0015]
When the contact pressure is large, the voltage V ₀ is applied to the voltage supply terminal 80, an A / D converter (not shown) is connected to the A / D port 81, and the coordinates of the pressed point are detected. The voltage V ₁ to D port 81 is
V ₁ = R ₂ R ₄ V ₀ / ((R ₁ + R ₂ ) R ₃ + R ₁ R ₂ + (R ₁ + R ₂ ) R ₄ ) (4)
It is represented by Here, since R ₄ is very large with respect to R _{1 to} R ₃ , R ₃ can be ignored. Therefore, equation (4) is
V ₁ = R ₂ V ₀ / (R ₁ + R ₂ ) (5)
It becomes.
[0016]
Here, smaller contact pressure when the user presses the touch panel 71, when the contact resistance is increased, when Nachi Suwa, the contact area is small, R ₃ terms can not be neglected. The voltage V ₁ ′ to the A / D port 81 when the contact area is small is obtained from the equation (4):
V ₁ '= R ₂ R ₄ V ₀ / ((R ₁ + R ₂ ) (R ₃ + R ₄ )) (6)
It becomes.
[0017]
Therefore, it can be seen from the equations (4) and (6) that V ₁ > V ₁ ′. That is, when the contact area is small, the voltage to the A / D port 81 is lower than that when the contact area is large.
[0018]
As described above, when the contact area to the touch panel 71 is small, an error occurs in the detected coordinates, and as a result, the coordinates of the correct pressing point cannot be detected. For this reason, there is a problem that it is mistaken that the other place is pressed and malfunctions.
[0019]
The present invention has been made to solve this problem, and an object of the present invention is to provide a touch panel device that does not malfunction even when the contact area to the touch panel is small, that is, not affected by the contact resistance. It is.
[0020]
[Means for Solving the Problems]
The present invention provides a first resistive film having a pair of electrodes facing each other so as to be parallel to the X axis, and a second resistance film having a pair of electrodes facing each other so as to be parallel to the Y axis. This is a touch panel device that detects the pressed position coordinates of a resistive film type touch panel in which a resistive film is bonded with a spacer interposed therebetween. In the touch panel device, the state setting unit applies a constant voltage between the electrodes of one resistance film when detecting each axis coordinate of the pressed position, opens the electrode terminal of the other resistance film, and One electrode terminal of the resistance film is used as a coordinate detection terminal, and this terminal is pulled up and pulled down via a resistor. The coordinate detection unit reads the output voltage of the coordinate detection terminal at the time of pull-up and pull-down. If the difference is smaller than a set value, the coordinate detection unit detects the coordinate based on the output voltage. In this way, the coordinates are detected only when the contact area is large when pressed down correctly, and the coordinates are not detected when the contact area is small, so that erroneous coordinates detection does not cause malfunction.
[0021]
Also, the coordinate detection unit reads the output voltage of the coordinate detection terminal at the time of pull-up and pull-down, and if the difference is smaller than a set value, the average of the output voltage at the pull-up and the output voltage at the pull-down Based on the voltage, the coordinates of the pressed position are detected. In this way, when the contact area is large, the coordinates of the pressed position can be detected correctly.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
(A) Outline of the Present Invention The outline of the present invention will be described with reference to FIG. FIG. 1A shows an equivalent circuit in a pull-down state when the touch panel is pressed. In the figure, 11 and 12 are resistances R ₁ and R ₂ of the resistance film between the pressing point and the electrode, 13 is a contact resistance R ₃ , 14 is a pull-down / pull-up resistance, 15 is a voltage supply terminal, 16 is A / D ports are shown respectively. R ₁ + R ₂ is several hundred Ω, R ₃ is several hundred Ω when the contact resistance is large, and R ₄ is several tens kΩ. .
[0023]
When the voltage V ₀ is applied to the voltage supply terminal 15 and an A / D converter (not shown) is connected to the A / D port 16 and the coordinates of the pressed point are detected, the voltage V to the A / D port 16 is detected. ₁ is
V ₁ = R ₂ R ₄ V ₀ / ((R ₁ + R ₂ ) R ₃ + R ₁ R ₂ + (R ₁ + R ₂ ) R ₄ ) (7)
It is represented by Here, since R ₄ is very large with respect to R _{1 to} R ₃ , R ₃ and R ₁ R ₂ can be ignored. Therefore, equation (7) is
V ₁ = R ₂ / V ₀ (R ₁ + R ₂ ) (8)
It becomes.
[0024]
Here, when the contact resistance is large, that is, when the contact area is small, the R ₃ term cannot be ignored. The voltage V ₁ ′ to the A / D port 16 when this contact area is small can be calculated from the equation (7):
V ₁ ′ = R ₂ R ₄ V ₀ / ((R ₁ + R ₂ ) (R ₃ + R ₄ )) (9)
It becomes.
[0025]
Therefore, it can be seen from the equations (7) and (9) that V ₁ > V ₁ ′. That is, when the contact area is small, the voltage to the A / D port 16 is lower than that when the contact area is large.
[0026]
FIG. 1B shows an equivalent circuit in a pull-up state. When a voltage V ₀ is applied to the voltage supply terminal 15 and an A / D converter is connected to the A / D port 16 to detect the coordinates of the pressed point, the voltage V ₂ to the A / D port 16 is
V ₂ = V _0- (R ₁ R ₄ V ₀ / ((R ₁ + R ₂ ) R ₃ + R ₁ R ₂ + (R ₁ + R ₂ ) R ₄ )) (10)
It is represented by Here, since R ₄ is very large with respect to R _{1 to} R ₃ , R ₃ and R ₁ R ₂ can be ignored. Therefore, equation (10) is
V ₂ = V ₀ − (R ₁ V ₀ / (R ₁ + R ₂ )) = R ₂ V ₀ / (R ₁ + R ₂ ) (11)
This is the same as the equation (8) indicating the voltage value at the time of pull-down.
[0027]
Here, when the contact resistance is large, that is, when the contact area is small, the R ₃ term cannot be ignored. The voltage V ₂ ′ to the A / D port 16 when this contact area is small is obtained from the equation (10):
V ₂ '= V _0- (R ₁ R ₄ V ₀ / ((R ₁ + R ₂ ) (R ₃ + R ₄ ))) (12)
It becomes.
[0028]
Therefore, it can be seen from the equations (10) and (12) that V ₂ ′> V ₂ . That is, when the contact area is small, the voltage to the A / D port 16 is higher than that when the contact area is large.
[0029]
FIG. 1C shows the output voltage in the pull-down state and the pull-up state when the contact resistance R ₃ is small, and FIG. 1D shows the pull-down state when the contact resistance R ₃ is large. The output voltage in the pull-up state is illustrated. As shown in both figures, when the contact resistance R ₃ is small, both V ₁ and V ₂ are close to true values, and when the contact resistance is large, the output voltages V ₁ ′ and V ₂ ′ are large between the true values. It can be seen that an error occurs.
[0030]
Therefore, as shown in FIG. 1E, the present invention detects the output voltage at the time of pull-down and at the time of pull-up, and calculates the difference between them. A coordinate detection unit is provided that detects the coordinates based on the output voltage if the difference is smaller than a predetermined set value, and disables coordinate detection when the difference in output voltage is greater than the set value. In this way, when the error is large, the value is not used.
[0031]
Further, in the present invention, when the difference between the output voltages of the coordinate detection terminals at the time of pull-up and pull-down is smaller than a predetermined set value, the average of the output voltage at the time of pull-up and the output voltage at the time of pull-down The voltage is calculated, and the coordinates of the pressed position are detected based on the voltage. By doing in this way, since the average value of the detected output voltage is used, the touch panel which is not influenced by contact resistance more can be provided.
[0032]
(B) Embodiment FIG. 2 is a block diagram of the touch panel device of the present invention. In FIG. 2, 21 is a touch panel, 22 is an electrode state setting unit, 23 is a coordinate detection unit having a microcomputer configuration, and 24 is a pull-down / pull-up state setting unit.
[0033]
The electrode state setting unit 22 is for controlling the states of the panel terminals U, D, R, and L of the touch panel, and includes transistors 22a to 22e. A voltage of 5 V is applied to the electrode state setting unit 22 from the outside via the terminal 25, and a predetermined control voltage is applied from the coordinate detection unit 23.
[0034]
The coordinate detection unit 23 controls the electrode state setting unit 22 to detect the coordinates of the pressed point, and includes SEL1 to SEL4 terminals, an X terminal, and a Y terminal. Although not particularly illustrated, the coordinate detection unit 23 includes an A / D converter and a storage unit. The A / D converter is connected to the X terminal and the Y terminal. The storage unit stores a set value for comparing the difference in output voltage when pulled down or pulled up. The pull-down / pull-up state setting unit 24 is for pulling down or pulling up a terminal for detecting coordinates (hereinafter, referred to as a coordinate detection terminal) among the panel terminals of the touch panel 21 and has two pull-down / pull-up resistors. Have.
[0035]
When detecting the coordinates of the pressed point, the coordinate detection unit 23 changes the control voltage applied from the SEL1 to SEL4 to the electrode state setting unit 22 as shown in the table of FIG. Here, when the coordinate detection unit 23 detects the X coordinate of the pressed point, the coordinate detection unit 23 changes the control voltage so that the coordinate detection terminal X is pulled down and pulled up. For example, when the X coordinate is detected by pulling down the coordinate detection terminal X, the coordinate detection unit 23 applies 5 V (H) from SEL2 and sets SEL1, SEL3, and SEL4 to 0 V (L). Then, the U and D terminals of the touch panel 21 are opened, the R terminal is 5 V, the L terminal is grounded, and the coordinate detection terminal X is pulled down. Further, when the coordinate detection terminal X is pulled up to detect the X coordinate, the coordinate detection unit 23 applies 5V from SEL2 and SEL4, and sets SEL1 and SEL3 to 0V. Then, the U and D terminals of the touch panel 21 are opened, the R terminal is 5 V, the L terminal is grounded, and the coordinate detection terminal X is pulled up. Then, the coordinate detection unit 23 detects the X coordinate of the pressed point from the voltage detected at the X terminal.
[0036]
Similarly, when detecting the Y coordinate of the pressed point, the coordinate detection unit 23 changes the control voltage applied to the electrode state setting unit 22 so that the coordinate detection terminal Y is pulled down and pulled up. Here, when the Y coordinate is detected by pulling down the coordinate detection terminal Y, the coordinate detection unit 23 applies 5V from SEL1 and SEL3, and sets SEL2 and SEL4 to 0V. Then, the R and L terminals of the touch panel 21 are opened, a voltage of 5 V is applied to the U terminal, the D terminal is grounded, and the coordinate detection terminal Y is pulled down. Further, when the Y coordinate is detected by pulling up the coordinate detection terminal Y, the coordinate detection unit 23 applies 5V from SEL1, SEL3, and SEL4, and sets SEL2 to 0V. Then, the R and L terminals of the touch panel 21 are opened, a voltage of 5 V is applied to the U terminal, the D terminal is grounded, and the coordinate detection terminal Y is pulled up. The coordinate detection unit 23 detects the Y coordinate of the pressed point from the voltage detected at the Y terminal.
[0037]
When the X and Y coordinates of the pressed point are obtained, the coordinate detection unit 23 sends a predetermined control signal associated with the area including the detected coordinates of the pressed point to various devices connected to the coordinate detection unit 23 ( (Not shown) to control various connected devices.
[0038]
(C) Processing The operation of the touch panel device of the present invention will be described with reference to the flowchart of FIG. First, when the user presses the touch panel with a finger or a pen, the coordinate detection unit 23 applies a control voltage to the electrode state setting unit 22 so that the coordinate detection terminal X is pulled down, and the output voltage when the pull down is performed. (Hereinafter referred to as X pull-down value) is detected (step 101). Next, the coordinate detection unit 23 applies a control voltage to the electrode state setting unit 22 so that the coordinate detection terminal X is pulled up, and detects an output voltage (hereinafter referred to as an X pull-down value) when pulled up. (Step 102).
[0039]
Next, the coordinate detection unit 23 applies a control voltage to the electrode state setting unit 22 so that the coordinate detection terminal Y pulls down, and detects an output voltage (hereinafter referred to as a Y pull-down value) when pulled down (step). 103). The coordinate detection unit 23 applies a control voltage to the electrode state setting unit 22 so that the coordinate detection terminal Y is pulled up, and detects an output voltage (hereinafter referred to as a Y pull-up value) when pulled up. (Step 104).
[0040]
Thereafter, the coordinate detection unit 23 calculates the difference between the X pull-down value and the X pull-up value and the voltage difference ΔX, ΔY between the Y pull-down value and the Y pull-up value (step 105). Then, the coordinate detection unit 23 compares the output voltage differences ΔX and ΔY calculated in step 105 with the set value V _S stored in the storage unit. Here, when the output voltage differences ΔX and ΔY calculated in step 105 are both smaller than the set value V _S (step 106), the coordinate detection unit 23 calculates the average value of the X pull-down value and the X pull-up value, and The average value of the Y pull-down value and the Y pull-up value is calculated (step 107). In step 106, when the difference ΔX, ΔY between the output voltages calculated in step 105 is larger than the set value V _S , it is determined that there is no contact, and an X pull-down value, an X pull-up value, a Y pull-down value, and a Y pull The up value is discarded (step 108).
[0041]
Then, the coordinate detection unit 23 determines the pressed point based on the average value calculated in Step 107 (Step 109). Thereafter, the coordinate detection unit 23 outputs a predetermined control signal associated with the area including the pressed coordinate to various devices (not shown) connected to the coordinate detection unit 23 to connect to it. Control various devices.
[0042]
【The invention's effect】
As described above, according to the present invention, when detecting each axis coordinate of the pressed position, a constant voltage is applied between the electrodes of one resistance film, the electrode terminal of the other resistance film is opened, and the other One electrode terminal of the resistance film is used as a coordinate detection terminal, and this terminal is pulled up and pulled down via a resistor, and the output voltage of the coordinate detection terminal at the time of pull-up and pull-down is read, and the difference is smaller than the set value. For example, coordinates can be detected based on output voltage, and coordinates can not be detected if the voltage is large. Therefore, when the error is large, the value is not used, and a touch panel device that is not affected by contact resistance is provided. Can do.
[0043]
Further, according to the present invention, the output voltage of the coordinate detection terminal at the time of pull-up and pull-down is read, and if the difference is smaller than a set value, the output voltage at the time of pull-up and the output voltage at the time of pull-down Based on the average voltage, the coordinates of the pressed position are detected. By doing in this way, a coordinate can be detected using the average value of the detected output voltage, and the touch panel which detects the correct coordinate value which is not influenced by contact resistance more can be provided.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory diagram of a touch panel device of the present invention.
FIG. 2 is a configuration diagram of a touch panel device of the present invention.
FIG. 3 is a correspondence table of control voltages applied to a state setting unit by a coordinate detection unit.
FIG. 4 is a flowchart for explaining the operation of the touch panel device of the present invention.
FIG. 5 is a principle explanatory diagram 1 of a touch panel device.
FIG. 6 is a principle explanatory diagram 2 of the touch panel device.
FIG. 7 is a principle explanatory diagram 3 of a touch panel.
FIG. 8 is a schematic diagram when attention is paid to an electrical part of the touch panel.
FIG. 9 is a configuration diagram of a conventional touch panel device.
FIG. 10 is a correspondence table of control voltages applied by the microcomputer unit to the state setting unit.
FIG. 11 is a diagram when the touch panel device is pressed.
FIG. 12 is a circuit diagram when a touch panel is pressed.
[Explanation of symbols]
11 Resistance R _{1 of} resistive film
12 Resistance R _{2 of} resistance film
13 Contact resistance R ₃
14 State setting unit resistor 15 Voltage supply terminal 16 A / D port 21 Touch panel 22 Electrode state setting unit 23 Coordinate detection unit 24 Pull-down / pull-up state setting unit 25 Terminal

Claims (2)

A first resistive film in which a pair of electrodes are arranged to face each other so as to be parallel to the X axis, and a second resistive film that is arranged to face a pair of electrodes so as to be parallel to the Y axis. In the touch panel device for detecting the pressing position coordinates of the resistive touch panel bonded with the spacer in between,
When detecting the coordinate of each axis of the pressed position, a certain voltage is applied between the electrodes of one resistance film, the electrode terminal of the other resistance film is opened, and one electrode terminal of the other resistance film is coordinated. A state setting unit that pulls up and pulls down this terminal via a resistor as a detection terminal,
A coordinate detection unit that reads the output voltage of the coordinate detection terminal at the time of pull-up and pull-down, detects a coordinate based on the output voltage if the difference is smaller than a set value, and disables coordinate detection if the difference is large,
A touch panel device comprising: The output voltage of the coordinate detection terminal at the time of pull-up and pull-down is read, and if the difference is smaller than a set value, based on the average voltage between the output voltage at the time of pull-up and the output voltage at the time of pull-down, the pressed position The touch panel device according to claim 1, wherein the coordinates are detected.

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