JP2014013441A - Control circuit and control method of touch panel, and touch panel input device and electronic apparatus using those - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve operational feeling of a resistance type touch panel.SOLUTION: A control circuit 100 includes a capacitance type coordinate detection unit 120 that detects coordinates touched by a user by using a resistance film type touch panel 4. A charging circuit 30 generates a potential difference between a first terminal P1 and a second terminal P2 to charge a first resistance film RF1. A charge detection circuit 30 measures an amount of charge stored in the first resistance film RF1 through the charging by the charging circuit 30. A coordinate calculation unit 36 detects coordinates touched by a user on the basis of the measured amount of charge.

Description

  The present invention relates to a resistive film type touch panel.

  2. Description of the Related Art In recent years, electronic devices such as computers, mobile phone terminals, and PDAs (Personal Digital Assistants) are mainly provided with an input device for operating electronic devices by touching with a finger. As such an input device, a resistance film type (also referred to as resistance type) touch panel (touch sensor) and a capacitance type (also referred to as electrostatic type) touch panel are known (Patent Document 1).

JP 2009-48233 A

  The resistive touch panel has two resistive films provided to overlap each other. When the user's finger or stylus comes into contact with the panel, the resistive films are deformed to contact each other, and the combined resistance of the two resistive films changes. By detecting the amount of change in the combined resistance, the coordinates touched by the user can be determined.

  On the other hand, the electrostatic touch panel includes a sensor electrode that forms a capacitance. As the user approaches the panel, the capacitance changes. By detecting the amount of change in capacitance, the coordinates touched by the user can be determined.

  In the electrostatic method, since the detection target is limited to a dielectric material, it is difficult to detect a gloved finger or a stylus pen. On the other hand, the resistance type has an advantage that the detection target is not limited to a dielectric material, but the resistance film needs to be physically deformed, so that the operational feeling is inferior to the electrostatic method.

  The present invention has been made in such a situation, and one of the exemplary purposes of an aspect thereof is to improve the operational feeling of the resistive touch panel.

  One embodiment of the present invention relates to a control circuit for a touch panel. The touch panel includes first, second, third, and fourth terminals, a first resistance film in which one side extending in the first direction is connected to the first terminal, and a side opposite to the first resistor is connected to the second terminal, A second resistive film disposed with a gap between the first resistive film and extending in a second direction perpendicular to the first direction and connected to the third terminal, and an opposite side connected to the fourth terminal; Have. The control circuit generates a potential difference between the first terminal and the second terminal and charges the first resistance film, and charge detection that measures the amount of charge stored in the first resistance film by charging by the charging circuit A circuit, and a coordinate calculation unit that detects coordinates touched by a user based on the amount of charge.

  When the user brings a finger or the like close to the panel, the capacitance of the first resistance film increases in the vicinity of the close portion. The charge stored in the increased capacitance component increases (or decreases) closer to the first terminal, and decreases (or increases) closer to the second terminal. Therefore, by measuring the amount of charge stored in the first resistance film, the coordinates touched by the user can be detected. Since this coordinate detection method does not require deformation of the resistive film due to contact, the operational feeling can be improved.

  Another embodiment of the present invention is also a control circuit. The control circuit includes a first driver that outputs a high level voltage or a low level voltage, a second driver that outputs a high level voltage or a low level voltage, and a first output having one end connected to the output of the first driver. A switch, a second output switch having one end connected to the output of the second driver, a first switch provided between the other end of the first output switch and the first terminal, and the other end of the second output switch And a second switch provided between the second terminal, a third switch provided between the other end of the first output switch and the third terminal, and between the other end of the second output switch and the fourth terminal. And a first input switch having one end connected to the first input terminal of the fully differential amplifier and the other end connected to the other end of the first output switch. One end of which is fully differential A second input switch connected to the second input terminal and having the other end connected to the other end of the second output switch, and a second input switch provided between the first output terminal and the first input terminal of the fully differential amplifier. 1 capacitor, a second capacitor provided between the second output terminal and the second input terminal of the fully differential amplifier, and a coordinate calculation unit for detecting coordinates touched by the user based on the output signal of the fully differential amplifier And comprising.

  Yet another embodiment of the present invention is also a control circuit. The control circuit includes a first driver that outputs a high level voltage or a low level voltage, a second driver that outputs a high level voltage or a low level voltage, and a first output having one end connected to the output of the first driver. A switch, a second output switch having one end connected to the output of the second driver, a first switch provided between the other end of the first output switch and the first terminal, and the other end of the second output switch And a second switch provided between the second terminal, a third switch provided between the other end of the first output switch and the third terminal, and between the other end of the second output switch and the fourth terminal. A fourth switch, a differential amplifier having a reference voltage applied to its first input terminal, one end connected to the second input terminal of the differential amplifier, and the other end to the other of the first output switch A third input switch connected to the end A fourth input switch having one end connected to the second input terminal of the differential amplifier and the other end connected to the other end of the second output switch; and an output terminal and a second input terminal of the differential amplifier. A third capacitor provided therebetween, and a coordinate calculation unit that detects coordinates touched by the user based on an output signal of the differential amplifier.

  Yet another embodiment of the present invention is also a control circuit. The control circuit includes a first driver that outputs a high level voltage or a low level voltage, a second driver that outputs a high level voltage or a low level voltage, and a first output having one end connected to the output of the first driver. A switch, a second output switch having one end connected to the output of the second driver, a first switch provided between the other end of the first output switch and the first terminal, and the other end of the second output switch And a second switch provided between the second terminal, a third switch provided between the other end of the first output switch and the third terminal, and between the other end of the second output switch and the fourth terminal. A fourth switch, a differential amplifier having a first input terminal connected to the output terminal, one end connected to the second input terminal of the differential amplifier, and the other end of the first output switch. 5th input connected to the other end Switch, one end connected to the first input terminal of the differential amplifier and the other end connected to the other end of the second output switch, and the user contacts based on the output signal of the differential amplifier And a coordinate calculation unit that detects the coordinates.

  Another embodiment of the present invention relates to an electronic device. The electronic device may include the touch panel input device described above.

  Note that any combination of the above-described components, or a conversion of the expression of the present invention between methods, apparatuses, and the like is also effective as an aspect of the present invention.

  According to an aspect of the present invention, the operational feeling of the resistance touch panel is improved.

It is a block diagram which shows the structure of an electronic device provided with the touchscreen input device which concerns on embodiment. It is the equivalent circuit schematic of the touch panel at the time of the single touch which a user contacts a panel at one point. FIGS. 3A and 3B are equivalent circuit diagrams of the first resistance film. It is a figure which shows the relationship between the node number j which a user contacts, and the electric charge amount of a 1st resistance film. 5A to 5C are circuit diagrams illustrating a configuration example of the capacitive coordinate detection unit. It is a time chart which shows operation | movement of the electrostatic capacitance type coordinate detection part of Fig.5 (a). 7A and 7B are diagrams illustrating an electronic device including an input device.

  The present invention will be described below based on preferred embodiments with reference to the drawings. The same or equivalent components, members, and processes shown in the drawings are denoted by the same reference numerals, and repeated descriptions are omitted as appropriate. The embodiments do not limit the invention but are exemplifications, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention.

In this specification, “the state in which the member A is connected to the member B” means that the member A and the member B are electrically connected to each other in addition to the case where the member A and the member B are physically directly connected. It includes cases where the connection is indirectly made through other members that do not substantially affect the general connection state, or that do not impair the functions and effects achieved by their combination.
Similarly, “the state in which the member C is provided between the member A and the member B” refers to the case where the member A and the member C or the member B and the member C are directly connected, as well as their electric It includes cases where the connection is indirectly made through other members that do not substantially affect the general connection state, or that do not impair the functions and effects achieved by their combination.

  FIG. 1 is a block diagram illustrating a configuration of an electronic device 1 including a touch panel input device (simply referred to as an input device) 2 according to an embodiment. The input device 2 is disposed, for example, on the surface of an LCD (Liquid Crystal Display) 8 and functions as a touch panel. The input device 2 determines an X coordinate and a Y coordinate of a point (referred to as a contact point) touched by a user with a finger or a pen (hereinafter referred to as a finger 6).

  The input device 2 includes a touch panel 4 and a control circuit 100. The touch panel 4 is a 4-wire (4-terminal) resistive touch panel. Since the configuration of the touch panel 4 is general, it will be briefly described here.

  The touch panel 4 includes a first terminal P1 to a fourth terminal P4, a first resistance film RF1, and a second resistance film RF2. The first resistance film RF1 and the second resistance film RF2 are disposed so as to overlap with a gap in the Z-axis direction perpendicular to the X-axis and the Y-axis. One side E1 extending in the Y axis (first direction) of the first resistance film RF1 is connected to the first terminal P1. The side E2 facing the side E1 is connected to the second terminal P2. The third terminal P3 is connected to one side E3 extending in the X axis (second direction) of the second resistance film RF2, and the fourth terminal P4 is connected to one side E4 facing the side E3 of the second resistance film RF2. . The above is the configuration of the touch panel 4.

The control circuit 100 includes a first state φ1 for detecting coordinates in the X direction and a second state for detecting coordinates in the Y direction by drive control and calculation (referred to as resistance control) normally performed in the resistive touch panel 4. The state φ2 is repeated in a time-sharing manner to determine user input.
In addition, the control circuit 100 according to the embodiment uses, as a new technology, a third state φ3 for detecting coordinates in the X direction by a novel capacitance method using the resistive touch panel 4, and a Y state, The user's input is determined while switching the fourth state φ4 for detecting the direction coordinates in a time-sharing manner.

  The control circuit 100 includes a first terminal Pc1 to a fourth terminal Pc4, a resistance coordinate detection unit 110, and a capacitance coordinate detection unit 120, and is integrated on a single semiconductor substrate. “Integrated integration” includes the case where all of the circuit components are formed on a semiconductor substrate and the case where the main components of the circuit are integrated. A resistor, a capacitor, or the like may be provided outside the semiconductor substrate. The first terminal Pc1 to the fourth terminal Pc4 are respectively connected to the corresponding first terminal P1 to fourth terminal P4 on the touch panel 4 side.

  First, the configuration of the resistance coordinate detection unit 110 will be described. The resistance coordinate detection unit 110 detects the coordinates touched by the user based on the state of the first terminal P1 to the fourth terminal P4. The configuration and operation of the resistance coordinate detection unit 110 are not particularly limited, and a detection circuit of a resistance type panel that is known or can be used in the future can be used.

The resistance-type coordinate detection unit 110 in FIG. 1 includes a voltage generation unit 10, a voltage detection unit 20, and a coordinate calculation unit 26. First, a configuration for detecting coordinates in the X direction (X coordinates) will be described.
In the first state φ1, the voltage generator 10 applies predetermined first bias voltage Vb1 and second bias voltage Vb2 to the first terminal P1 and the second terminal P2, respectively. Here, Vb1> Vb2. Preferably, the second bias voltage Vb2 is the ground voltage (0V). In the first state, the voltage generator 10 places the third terminal P3 and the fourth terminal P4 in a high impedance state.

  The voltage detection unit 20 detects a voltage Vx (hereinafter referred to as a first panel voltage) Vx generated in at least one of the third terminal P3 and the fourth terminal P4 in the first state φ1. The voltage detection unit 20 includes a selector 22 and an A / D converter 24. For example, the selector 22 selects the voltage of the third terminal P3 in the first state φ1. The A / D converter 24 converts the first panel voltage Vx generated at the third terminal P3 into a digital value Dx.

The coordinate calculation unit 26 determines the X coordinate touched by the user based on the digital value Dx.
FIG. 2 is an equivalent circuit diagram of the touch panel 4 at the time of single touch where the user contacts the panel at one point. When the user contacts with the contact point PU, the first resistive film RF1 is divided resistor R1 ₁ between the contact point PU and the first terminal P1, the resistor R1 ₂ between the contact point PU and the second terminal P2. The first resistance film RF1 and the second resistance film RF2 are in contact at the contact point PU, and the contact resistance is Rc. The resistance of the path from the contact point PU of the second resistance film RF2 to the third terminal P3 is R2.

Potential of the contact point PU, since those obtained by dividing the bias voltage Vb1 and Vb2 at the resistor _R1 1, R1 _2, shows the X-coordinate of the contact point PU. Since the third terminal P3 has high impedance, the voltage Vx at the third terminal P3 is substantially equal to the potential at the contact point PU. That is, the panel voltage Vx generated at the third terminal P3 indicates the X coordinate of the contact point PU.

  The algorithm for deriving the X coordinate from the panel voltage Vx may be a known technique and is not particularly limited in the present invention.

Next, a configuration for detecting a coordinate in the Y direction (Y coordinate) will be described.
In the second state φ2, the voltage generator 10 applies predetermined first bias voltage Vb1 and second bias voltage Vb2 to the third terminal P3 and the fourth terminal P4, respectively. In the second state φ2, the voltage generator 10 places the first terminal P1 and the second terminal P2 in a high impedance state. The first bias voltage Vb1 in each of the first state and the second state may be the same value or different. Below, the case of the same value is demonstrated. The same applies to the second bias voltage Vb2.

  The voltage detector 20 detects a voltage Vy (hereinafter referred to as a second panel voltage) Vy generated in at least one of the first terminal P1 and the second terminal P2 in the second state φ2. For example, the selector 22 selects the voltage of the first terminal P1 in the second state φ2. The A / D converter 24 converts the second panel voltage Vy generated at the first terminal P1 into a digital value Dy. The coordinate calculation unit 26 calculates the Y coordinate touched by the user based on the digital value Dy.

  Note that, in the first state φ1, the voltage detection unit 20 may measure the voltage generated at the fourth terminal P4 as the panel voltage Vx instead of or in addition to the third terminal P3. Similarly, in the second state φ2, the voltage detection unit 20 may measure the voltage generated at the second terminal P2 as the panel voltage Vy instead of or in addition to the first terminal P1.

  The above is the configuration of the resistance coordinate detection unit 110. Next, the configuration of the capacitive coordinate detection unit 120 will be described.

  The capacitive coordinate detection unit 120 includes a charging circuit 30, a charge detection circuit 32, an A / D converter 34, and a coordinate calculation unit 36.

  A configuration for detecting coordinates in the X direction (X coordinate) will be described. In the third state φ3, the second resistance film RF2 may be fixed at a predetermined potential, or may be in a high impedance (open) state.

  The charging circuit 30 generates a potential difference between the first terminal P1 and the second terminal P2 in the third state φ3, and charges the first resistance film RF1. In the third state φ3, the charge detection circuit 32 measures the amount of charge Qx stored in the first resistance film RF1 by charging by the charging circuit 30, and generates a signal Vqx indicating the amount of charge Qx. The A / D converter 34 converts the charge amount Vqx into a digital value Dqx. The coordinate calculation unit 36 calculates the X coordinate touched by the user based on the digital value Dqx.

  Next, a configuration for detecting a coordinate in the Y direction (Y coordinate) will be described. In the fourth state φ4, the charging circuit 30 generates a potential difference between the third terminal P3 and the fourth terminal P4 to charge the second resistance film RF2. In the fourth state φ4, the charge detection circuit 32 measures the amount of charge Qy stored in the second resistance film RF2 by charging by the charging circuit 30, and generates a signal Vqy indicating the amount of charge Qy. The A / D converter 34 converts the signal Vqy into a digital value Dqy. The coordinate calculation unit 36 calculates the Y coordinate touched by the user based on the digital value Dqy.

  The above is the configuration of the control circuit 100. Next, the coordinate detection operation by the capacitive coordinate detection unit 120 will be described. Here, detection of the X coordinate will be described.

3A and 3B are equivalent circuit diagrams of the first resistance film RF1.
The first resistance film RF1 can be grasped as a distributed constant circuit, and a plurality of n (n is an integer) unit resistances ΔRs existing in series between the first terminal P1 and the second terminal P2, each of which is a unit. A plurality of n unit capacitors ΔCs existing between one end (node) of the resistor ΔRs and the ground. ΔCs × n is the total capacitance Cs of the first resistance film RF1.

FIG. 3A shows a state where the user is not touching the panel. In the third state φ3, the charging circuit 30 generates a potential difference ΔV between the first terminal P1 and the second terminal P2. Here, it is assumed that the high level voltage V _H is applied to the first terminal P1, and the low level voltage V _L is applied to the second terminal P2. In order to simplify the description, it is assumed that the low level voltage V _L is a ground voltage.

Since the resistance values of the unit resistors ΔRs are equal, the potential V _i of the i-th (1 ≦ i ≦ n) node is given by Expression (1).
V _i = V _H × i / n (1)

Further, the charge amount ΔQ _i stored in the i-th unit capacitance ΔCs _i is given by Expression (2).
ΔQ _i = V _i × ΔCs (2)

Therefore, the amount of charge Qx stored in the entire first resistance film RF1 is given by Expression (3).
Qx = Σ _{i = 1 to n} ΔQ _i = V _H / n × ΔCs × Σ _{i = 1 to n} i
_{= V H / n × ΔCs ×} n 2/2 = V H × Cs / 2 ... (3)

FIG. 3B shows a state where the user touches the panel at a point PU corresponding to the j-th node. The capacitance formed between the user's finger and the first resistive film RF1 referred to as C _F. At this time, the amount of charge ΔQ _F stored in the capacitor C _F is given by Expression (4).
ΔQ _F = V _j × C _F = V _H × j / n (4)

Therefore, the charge amount Qx which are stored when the user touches the point PU ', compared to the charge quantity Qx of the non-contact state of FIG. 3 (a), increases the charge amount Delta] Q _F min.
Qx ′ = Qx + V _H × j / n (5)

FIG. 4 is a diagram illustrating the relationship between the node number j that the user contacts and the charge amount Qx of the first resistance film RF1. If the capacitance C _F is formed by the user touches the panel is constant, the charge quantity Qx varies linearly with respect to the node number j. Here, since the node number j corresponds to the X coordinate, the X coordinate can be detected by charging the first resistance film RF1 and measuring the charge amount Qx stored in the first resistance film RF1. Recognize.

  Similarly, the Y coordinate can be detected in the fourth state φ4.

  Since the coordinate detection by the capacitive coordinate detection unit 120 uses the capacitance formed by the user's finger, unlike the original resistance film type coordinate detection, even if the first resistance film RF1 is not deformed. , Can detect the coordinates. Therefore, it is possible to provide a comfortable operational feeling similar to the case where a capacitance type panel is used.

Next, a specific configuration example of the capacitive coordinate detection unit 120 will be described.
FIGS. 5A to 5C are circuit diagrams illustrating a configuration example of the capacitive coordinate detection unit 120.

  5A to 5C, the charging circuit 30 and the charge detection circuit 32a are shared in time division for detection of the X coordinate and detection of the Y coordinate, and selectors 40 and 42 are provided for this purpose. The selectors 40 and 42 connect the charging circuit 30 and the charge detection circuit 32a to the first resistance film RF1 in the third state φ3 for detecting the X coordinate, and in the fourth state φ4 for detecting the Y coordinate, The charge detection circuit 32a is connected to the second resistance film RF2. The selector 40 includes a first switch SW1 and a third switch SW3, and the selector 42 includes a second switch SW2 and a fourth switch SW4.

The charging circuit 30 in FIG. 5A includes a first driver DR1, a second driver DR2, a first output switch SWb1, and a second output switch SWb2.
The first driver DR1 outputs one of a high level voltage _VH and a low level voltage _VL . The second driver DR2 outputs one of the high level voltage _VH and the low level voltage _{VL in} a complementary manner with the first driver DR1. In order to set the output of the charging circuit 30 to high impedance, a first output switch SWb1 and a second output switch SWb2 are provided as outputs of the first driver DR1 and the second driver DR2.

  In addition, when the charging circuit 30 and the voltage generation part 10 of FIG. 1 have the same function, they can be shared.

  The charge detection circuit 32a includes a fully differential amplifier 38a, a first input switch SWa1, a second input switch SWa2, a first capacitor C1, and a second capacitor C2.

One end of the first input switch SWa1 is connected to the first input terminal of the fully differential amplifier 38a, and the other end is connected to the first terminal P1 or the third terminal P3 via the first output switch SWb1 and the selector 40. The
One end of the second input switch SWa2 is connected to the second input terminal of the fully differential amplifier 38a, and the other end is connected to the third terminal P3 or the fourth terminal P4 via the second output switch SWb2 and the selector 42. The The first capacitor C1 is provided between the first output terminal and the first input terminal of the fully differential amplifier 38a, and the second capacitor C2 is provided between the second output terminal and the second input terminal of the fully differential amplifier 38a. Provided.

  The output of the charge detection circuit 32a is input to the differential input A / D converter 34.

FIG. 6 is a time chart showing the operation of the capacitance type coordinate detection unit 120 of FIG. Here, the X coordinate detection in the third state φ3 will be described.
In the third state φ3, the selector 40 and the selector 42 connect the charging circuit 30 and the charge detection circuit 32a to the first resistance film RF1 side. Specifically, the switches SW1 and SW2 are turned on, and SW3 and SW4 are turned off.

The capacitance type coordinate detection unit 120a sequentially executes the following processes.
Process 1. First, in a state where the first input switch SWa1 and the second input switch SWa2 are turned off, the first driver DR1 outputs the high level voltage V _H , the second driver DR2 outputs the low level voltage _VL , and the first output switch SWb1 The second output switch SWb2 is turned on. Thereby, the charging circuit 30 applies a predetermined driving voltage with the first polarity between the first terminal P1 and the second terminal P2 of the first resistive film RF1 (period T1).

  Process 2. In the subsequent period T2, the first output switch SWb1 and the second output switch SWb2 are turned off, and the charging circuit 30 is set to a high impedance state. Then, the first input switch SWa1 is turned on and the second input switch SWa2 is turned off. As a result, charge transfer occurs between the first capacitor C1 and the first resistance film RF1.

Process 3. In the subsequent period T3, the first input switch SWa1 and the second input switch SWa2 are turned off, the first driver DR1 outputs the low level voltage V _L , the second driver DR2 outputs the high level voltage V _H , and the first output switch SWb1 and second output switch SWb2 are turned on. Accordingly, the charging circuit 30 applies a predetermined driving voltage with the second polarity between the first terminal P1 and the second terminal P2 of the first resistive film RF1.

  Process 4. In the subsequent period T4, the first input switch SWb1 and the second input switch SWb2 are turned off, and the charging circuit 30 is set to a high impedance state. Then, the first input switch SWa1 is turned off and the second input switch SWa2 is turned on. As a result, charge transfer occurs between the second capacitor C2 and the first resistance film RF1.

  Process 5. In the subsequent period T5, the output voltage of the fully differential amplifier 38a is converted into a digital value by the A / D converter 34. This digital value indicates the amount of charge Qx stored in the first resistance film RF1.

  As described above, according to the capacitive coordinate detection unit 120a of FIG. 5A, the charge amount Qx of the first resistive film RF1 can be measured.

The capacitance type coordinate detection unit 120b in FIG. 5B is different from the charge detection circuit 32a in the configuration of the charge detection circuit 32b. The charge detection circuit 32b includes a differential amplifier 38b, a third input switch SWa3, a fourth input switch SWa4, and a third capacitor C3.
A reference voltage _VREF is applied to the first input terminal of the differential amplifier 38b. The reference voltage V _REF may be a midpoint voltage between the high level voltage V _H and the low level voltage V _L.

  One end of the third input switch SWa3 is connected to the first terminal P1 or the third terminal P3 via the selector 40, and the other end is connected to the second input terminal of the differential amplifier 38b. One end of the fourth input switch SWa4 is connected to the second terminal P2 or the fourth terminal P4 via the selector 42, and the other end is connected to the second input terminal of the differential amplifier 38b. The third capacitor C3 is provided between the output terminal of the differential amplifier 38b and the second input terminal.

The operation of the capacitive coordinate detection unit 120b in FIG. 5B will be described. The capacitive coordinate detection unit 120b sequentially executes the following processes.
Process 1. With the third input switch SWa3 and the fourth input switch SWa4 turned off, the charging circuit 30 applies a predetermined drive voltage between the first terminal P1 and the second terminal P2 of the first resistance film RF1. Thereby, the first resistance film RF1 is charged.

  Process 2. The charging circuit 30 is set to a high impedance state, the third input switch SWa3 is turned on, and the fourth input switch SWa4 is turned off.

Process 3. The charging circuit 30 is set to a high impedance state, and the third input switch SWa3 and the fourth input switch SWa4 are turned off.
Process 4. The output voltage of the differential amplifier 38 b is converted into a digital value by the A / D converter 34. This digital value indicates the amount of charge Qx stored in the first resistance film RF1.

  The charge amount Qx of the first resistance film RF1 can also be measured by the capacitive coordinate detection unit 120b of FIG.

Reference is made to the capacitive coordinate detection unit 120c of FIG. The charge detection circuit 32c includes a differential amplifier 38c, a fifth input switch SWa5, and a sixth input switch SWa6.
The first input terminal of the differential amplifier 38c and its output terminal are connected. One end of the fifth input switch SWa5 is connected to the first terminal P1 or the third terminal P3 via the selector 40, and the other end is connected to the second input terminal of the differential amplifier 38c. One end of the sixth input switch SWa6 is connected to the second terminal P2 or the fourth terminal P4 via the selector 42, and the other end is connected to the first input terminal of the differential amplifier 38c.

  The charge amount of the first resistance film RF1 can also be measured by this capacitive coordinate detection unit 120c.

  Finally, the use of the control circuit 100 will be described. FIGS. 7A and 7B are diagrams illustrating an electronic apparatus including the input device 2. 7A is a mobile phone terminal, a tablet PC, a game device, a portable audio player, or the like. The touch panel 4 is provided so as to overlap the display panel 8. The control circuit 100 is built in the housing 502 of the electronic device 500.

  The electronic device 600 in FIG. 7B is a display device such as a display of a personal computer, a display of a car navigation system, or a television. The touch panel 4 is provided so as to overlap with the LCD 8. The control circuit 100 is built in the housing 602 of the electronic device 600.

  According to the electronic devices of FIGS. 7A and 7B, it is possible to provide a comfortable operational feeling while using the resistive touch panel 4.

  Although the present invention has been described using specific terms based on the embodiments, the embodiments only illustrate the principles and applications of the present invention, and the embodiments are defined in the claims. Many variations and modifications of the arrangement are permitted without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Electronic device, 2 ... Input device, 4 ... Touch panel, 6 ... Finger, 8 ... Display panel, 100 ... Control circuit, 110 ... Resistance type coordinate detection part, 120 ... Capacitance type coordinate detection part, P1 ... 1st Terminal, P2 ... second terminal, P3 ... third terminal, P4 ... fourth terminal, RF1 ... first resistance film, RF2 ... second resistance film, 10 ... voltage generation section, 20 ... voltage detection section, 22 ... selector, 24 ... A / D converter, 26 ... coordinate operation unit, 30 ... charge circuit, 32 ... charge detection circuit, 34 ... A / D converter, 36 ... coordinate operation unit, DR1 ... first driver, DR2 ... second driver, SWb1 ... 1st output switch, SWb2 ... 2nd output switch, 38 ... Amplifier, C1 ... 1st capacitor, C2 ... 2nd capacitor, C3 ... 3rd capacitor, SWa1 ... 1st input switch, SWa2 ... 2nd input switch SWA3 ... third input switch, SWa4 ... fourth input switch, SWA5 ... fifth input switch, SWA6 ... sixth input switch, 40, 42 ... selectors.

Claims (20)

The first, second, third, and fourth terminals, one side extending in the first direction is connected to the first terminal, and the side opposite to the first resistance film is connected to the second terminal; A second resistive film disposed with a gap between the first resistive film and extending in a second direction perpendicular to the first direction and connected to the third terminal, and a side facing the third resistive film being connected to the fourth terminal; A control circuit for a touch panel comprising:
A charging circuit that generates a potential difference between the first terminal and the second terminal and charges the first resistance film;
A charge detection circuit that measures the amount of charge stored in the first resistive film by charging by the charging circuit;
A coordinate calculation unit for detecting coordinates touched by a user based on the charge amount;
A control circuit comprising: The charge detection circuit includes:
A fully differential amplifier,
A first input switch provided between the first terminal and the first input terminal of the fully differential amplifier;
A second input switch provided between the second terminal and the second input terminal of the fully differential amplifier;
A first capacitor provided between a first output terminal and a first input terminal of the fully differential amplifier;
A second capacitor provided between a second output terminal and a second input terminal of the fully differential amplifier;
The control circuit according to claim 1, comprising: The control circuit includes:
With the first input switch and the second input switch turned off, the charging circuit applies a predetermined drive voltage with a first polarity between the first terminal and the second terminal of the first resistance film. Applying, and
Placing the charging circuit in a high impedance state, turning on the first input switch and turning off the second input switch;
With the first input switch and the second input switch turned off, the charging circuit applies a predetermined drive voltage with a second polarity between the first terminal and the second terminal of the first resistance film. Applying, and
Placing the charging circuit in a high impedance state, turning off the first input switch, and turning on the second input switch;
Placing the charging circuit in a high impedance state and turning off the first input switch and the second input switch;
The control circuit according to claim 2, wherein the control circuit is configured to be switchable. The charge detection circuit includes:
A differential amplifier having a reference voltage applied to the first input terminal;
A third input switch provided between the first terminal and the second input terminal of the differential amplifier;
A third capacitor provided between the output terminal of the differential amplifier and the second input terminal;
The control circuit according to claim 1, comprising:   5. The control circuit according to claim 4, wherein the reference voltage is a midpoint voltage of a voltage applied to each of the first input terminal and the second input terminal by the charging circuit. The control circuit includes:
Applying a predetermined drive voltage between the first terminal and the second terminal of the first resistive film by the charging circuit with the third input switch turned off;
Placing the charging circuit in a high impedance state and turning on the third input switch;
Placing the charging circuit in a high impedance state and turning off the third input switch;
The control circuit according to claim 5, wherein the control circuit is configured to be switchable. The charge detection circuit includes:
A differential amplifier having a first input terminal connected to the output terminal;
A fifth input switch provided between the first terminal and the second input terminal of the differential amplifier;
A sixth input switch provided between the second terminal and the first input terminal of the differential amplifier;
The control circuit according to claim 1, comprising: The control circuit includes:
Applying a predetermined drive voltage with a first polarity between the first terminal and the second terminal of the first resistive film by the charging circuit with the fifth input switch turned off;
Placing the charging circuit in a high impedance state and turning on the fifth input switch;
Placing the charging circuit in a high impedance state and turning off the fifth input switch;
The control circuit according to claim 7, wherein the control circuit is configured to be switchable.   The charging circuit includes a first state in which a first polarity is charged between the first terminal and the second terminal of the first resistive film, a second state in which a charge is charged between the first terminal and the second terminal, and a high state. The control circuit according to claim 1, wherein the control circuit is configured to be switchable between impedance states. The charging circuit is
A first driver that applies a first voltage to the first terminal in the first state and a second voltage to the first terminal in the second state;
A second driver that applies a second voltage to the second terminal in the first state, and applies a first voltage to the second terminal in the second state;
The control circuit according to claim 9, comprising: The charging circuit is
A first output switch provided between the output terminal of the first driver and the first terminal and turned on in the first and second states and turned off in the high impedance state;
A second output switch provided between the output terminal of the second driver and the second terminal and turned on in the first and second states and turned off in the high impedance state;
The control circuit according to claim 10, further comprising: The charging circuit generates a potential difference between the third terminal and the fourth terminal, and is configured to be able to charge the second resistance film,
The control circuit according to claim 1, wherein the charge detection circuit is configured to be able to measure an amount of charge stored in the second resistance film by charging by the charging circuit.   And a selector that switches between a state in which the charging circuit and the charge detection circuit are connected to the first resistance film and a state in which the charging circuit and the charge detection circuit are connected to the second resistance film. The control circuit according to claim 12. The first, second, third, and fourth terminals, one side extending in the first direction is connected to the first terminal, and the side opposite to the first resistance film is connected to the second terminal; A second resistive film disposed with a gap between the first resistive film and extending in a second direction perpendicular to the first direction and connected to the third terminal, and a side facing the third resistive film being connected to the fourth terminal; A control circuit for a touch panel comprising:
A first driver that outputs a high level voltage or a low level voltage;
A second driver that outputs a high level voltage or a low level voltage;
A first output switch having one end connected to the output of the first driver;
A second output switch having one end connected to the output of the second driver;
A first switch provided between the other end of the first output switch and the first terminal;
A second switch provided between the other end of the second output switch and the second terminal;
A third switch provided between the other end of the first output switch and the third terminal;
A fourth switch provided between the other end of the second output switch and the fourth terminal;
A fully differential amplifier,
A first input switch having one end connected to the first input terminal of the fully differential amplifier and the other end connected to the other end of the first output switch;
A second input switch having one end connected to the second input terminal of the fully differential amplifier and the other end connected to the other end of the second output switch;
A first capacitor provided between a first output terminal and a first input terminal of the fully differential amplifier;
A second capacitor provided between a second output terminal and a second input terminal of the fully differential amplifier;
Based on the output signal of the fully differential amplifier, a coordinate calculation unit that detects coordinates touched by the user,
A control circuit comprising: The first, second, third, and fourth terminals, one side extending in the first direction is connected to the first terminal, and the side opposite to the first resistance film is connected to the second terminal; A second resistive film disposed with a gap between the first resistive film and extending in a second direction perpendicular to the first direction and connected to the third terminal, and a side facing the third resistive film being connected to the fourth terminal; A control circuit for a touch panel comprising:
A first driver that outputs a high level voltage or a low level voltage;
A second driver that outputs a high level voltage or a low level voltage;
A first output switch having one end connected to the output of the first driver;
A second output switch having one end connected to the output of the second driver;
A first switch provided between the other end of the first output switch and the first terminal;
A second switch provided between the other end of the second output switch and the second terminal;
A third switch provided between the other end of the first output switch and the third terminal;
A fourth switch provided between the other end of the second output switch and the fourth terminal;
A differential amplifier having a reference voltage applied to the first input terminal;
A third input switch having one end connected to the second input terminal of the differential amplifier and the other end connected to the other end of the first output switch;
A fourth input switch having one end connected to the second input terminal of the differential amplifier and the other end connected to the other end of the second output switch;
A third capacitor provided between the output terminal of the differential amplifier and the second input terminal;
Based on the output signal of the differential amplifier, a coordinate calculation unit that detects coordinates touched by the user,
A control circuit comprising: The first, second, third, and fourth terminals, one side extending in the first direction is connected to the first terminal, and the side opposite to the first resistance film is connected to the second terminal; A second resistive film disposed with a gap between the first resistive film and extending in a second direction perpendicular to the first direction and connected to the third terminal, and a side facing the third resistive film being connected to the fourth terminal; A control circuit for a touch panel comprising:
A first driver that outputs a high level voltage or a low level voltage;
A second driver that outputs a high level voltage or a low level voltage;
A first output switch having one end connected to the output of the first driver;
A second output switch having one end connected to the output of the second driver;
A first switch provided between the other end of the first output switch and the first terminal;
A second switch provided between the other end of the second output switch and the second terminal;
A third switch provided between the other end of the first output switch and the third terminal;
A fourth switch provided between the other end of the second output switch and the fourth terminal;
A differential amplifier having a first input terminal connected to the output terminal;
A fifth input switch having one end connected to the second input terminal of the differential amplifier and the other end connected to the other end of the first output switch;
A sixth input switch having one end connected to the first input terminal of the differential amplifier and the other end connected to the other end of the second output switch;
Based on the output signal of the differential amplifier, a coordinate calculation unit that detects coordinates touched by the user,
A control circuit comprising:   17. The control circuit according to claim 1, wherein the control circuit is integrated on a single semiconductor substrate. The first, second, third, and fourth terminals, one side extending in the first direction is connected to the first terminal, and the side opposite to the first resistance film is connected to the second terminal; A second resistive film disposed with a gap between the first resistive film and extending in a second direction perpendicular to the first direction and connected to the third terminal, and a side facing the third resistive film being connected to the fourth terminal; And a touch panel having
The control circuit according to any one of claims 1 to 17, which controls the touch panel;
A touch panel input device comprising:   An electronic apparatus comprising the touch panel input device according to claim 18. The first, second, third, and fourth terminals, one side extending in the first direction is connected to the first terminal, and the side opposite to the first resistance film is connected to the second terminal; A second resistive film disposed with a gap between the first resistive film and extending in a second direction perpendicular to the first direction and connected to the third terminal, and a side facing the third resistive film being connected to the fourth terminal; A method of controlling a touch panel having
Generating a potential difference between the first terminal and the second terminal and charging the first resistance film;
Measuring the amount of charge stored in the first resistive film by charging;
Detecting coordinates touched by a user based on the charge amount;
A method comprising the steps of:

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