JP5479885B2 - Touch sensor and driving method thereof, display device with touch sensor, and electronic device - Google Patents

Description

  The present invention relates to a touch sensor for detecting an external proximity object, and more particularly to a touch sensor capable of detecting an external proximity object by a change in capacitance, a driving method thereof, a display device with a touch sensor, and an electronic apparatus.

  In recent years, attention has been paid to a display device in which a touch sensor for detecting contact with a finger or the like is arranged on a display screen or its peripheral portion. Since a display device having such a touch sensor does not require an input device such as a keyboard, a mouse, or a keypad, the use of the display device tends to increase in a portable information terminal such as a mobile phone as well as a computer. .

  For such touch sensors, for example, a display device is configured by mounting a touch sensor on a display screen such as a liquid crystal display unit, and information can be input by displaying various button images on the display screen. (For example, patent document 1 etc.). In addition, for example, a display device is configured by mounting a touch sensor on which a symbol indicating a function or the like is printed on the periphery (frame area) of a display screen such as a liquid crystal display unit, and information is displayed on the display screen based on the touch. Some of them display information, or others input information based on information displayed on the display screen (for example, Non-Patent Document 1).

JP 2006-148536 A

Xmini product introduction, [online], Sony Ericsson Mobile Communications Co., Ltd., [Searched on November 1, 2009], Internet <URL: http://www.sonyericsson.co.jp/product/au/xmini/ function / usability.html>

  By the way, in the portable information terminal, downsizing of the device is desired from the viewpoint of ease of carrying and use, and in the display device having the touch sensor described above, in addition to downsizing of the display unit, touch The challenge is how to save the sensor space.

  Since the touch sensor generally has low detection sensitivity with respect to an external proximity object, the presence or absence of the external proximity object is determined after the detected signal is amplified using a circuit such as an amplifier. In other words, the touch sensor having such a configuration increases the scale because the circuit is complicated, and as a result, it is difficult to realize space saving.

  The present invention has been made in view of such a problem, and an object thereof is a touch sensor having a high detection sensitivity to an external proximity object, having a simple circuit configuration, and capable of realizing space saving, a driving method thereof, and a touch sensor. It is to provide an attached display device and an electronic device.

  The touch sensor of the present invention includes a first electrode, a second electrode, a capacitive element, a drive control unit, and a detection unit. A capacitance is formed between the first electrode and the second electrode. The drive control unit drives at least the first electrode of the first and second electrodes, and connects between the second electrode and the capacitive element in synchronization with the drive operation of the first electrode. Control the state. The detection unit detects an external proximity object based on how the voltage of the capacitive element changes.

  The touch sensor driving method of the present invention drives at least the first electrode of the first and second electrodes in which the interelectrode capacitance is formed between them, and the driving operation of the first electrode. The connection state between the second electrode and the capacitive element is controlled in synchronization with each other, and an external proximity object is detected based on how the voltage of the capacitive element changes.

  The display device with a touch sensor of the present invention includes a display panel in which an image display unit and a touch sensor unit are integrally formed. The image display unit includes a plurality of display elements and performs image display based on the image signal. The touch sensor unit includes the touch sensor of the present invention, and is arranged in a frame area outside the effective display area of the image display unit. The display panel may have other display units in this frame area, for example. In this case, the other display unit desirably includes a display element having the same structure as the display element of the image display unit.

  An electronic apparatus according to the present invention includes the display device with an imaging function according to the present invention, and includes, for example, a television set, a digital camera, a personal computer, a video camera, or a mobile terminal device such as a mobile phone.

  In the touch sensor and the driving method thereof, the display device with a touch sensor, and the electronic device of the present invention, when the drive control unit drives the first electrode, the voltage of the second electrode is between the first and second electrodes. Due to the coupling of the capacitance between the electrodes, it changes based on the operating principle of a so-called switched capacitor. At this time, if there is an external proximity object, the capacitance between the electrodes changes, so the voltage of the second electrode corresponds to the presence or absence of the external proximity object. When the second electrode is connected to the capacitor, electric charge moves between the second electrode and the capacitor. In this way, by moving charges between the grounded capacitance formed between each of the first and second electrodes and the ground, the interelectrode capacitance, and the capacitive element, the capacitive element is moved. The voltage changes. The voltage of this capacitive element corresponds to the presence or absence of an external proximity object, and the external proximity object is detected based on this voltage.

When the drive control unit drives the first and second electrodes, it is possible to use the following two methods.

  The first method is a method in which the first electrode is driven as a drive electrode while the second electrode is used as a detection electrode. In this method, the drive control unit performs control so as to perform the following two operations, for example. In the first operation, the voltage levels of both the first and second electrodes are initialized, and the second electrode and the capacitive element are disconnected from each other. In the second operation, a driving voltage is applied to the first electrode, and the second electrode and the capacitive element are connected.

  In this method, for example, the first operation and the second operation may be controlled to be repeated. In this case, the detection unit can detect the external proximity object by using the fact that the change rate of the voltage of the capacitive element varies depending on the presence or absence of the external proximity object. In this case, the detection unit may detect an external proximity object based on the time until the voltage of the capacitive element reaches a predetermined threshold value, for example. Alternatively, the detection unit may detect an external proximity object based on the voltage level of the capacitive element when the first and second operations are repeated a predetermined number of times.

  The second method is a method in which both the first and second electrodes are driven as drive electrodes and the second electrode is used as a detection electrode. In this method, the drive control unit performs control so as to perform, for example, an initialization operation and a drive operation. In the initialization operation, the voltage levels of both the first electrode and the second electrode are initialized, and the second electrode and the capacitive element are disconnected from each other. The drive operation is performed subsequent to the initialization operation, and includes an operation of applying the first drive voltage to one of the first and second electrodes and an operation of applying the second drive voltage to the other. In the final operation of applying the first and second drive voltages to the first electrode, the second electrode and the capacitive element are connected.

  As a specific example of this method, for example, the following four operations are repeated in this order. The first operation is an initialization operation. In the second operation, the first drive voltage is applied to the first electrode while the second electrode and the capacitor are not connected. In the third operation, the second drive voltage is applied to the second electrode while the second electrode and the capacitor are not connected. In the fourth operation, the first drive voltage is applied to the first electrode, and the second electrode and the capacitive element are connected. Also in this case, the detection unit can detect the external proximity object by using the fact that the change rate of the voltage of the capacitive element varies depending on the presence or absence of the external proximity object.

  The detection unit may include, for example, a comparator circuit having a first switching element, another capacitive element, an inverting circuit, and a second switching element. The first switching element is disposed between the input terminal of the comparator circuit and the reference voltage terminal, and is on / off controlled. The other capacitor element has one terminal connected to the input terminal of the comparator circuit. The inverting circuit has its input connected to the other terminal of the other capacitive element, and its output connected to the output terminal of the comparator circuit. The second switching element is disposed between the input and output of the inverting circuit and is on / off controlled. In this comparator circuit, first, both the first and second switching elements are turned on, and the reference voltage applied to the reference voltage terminal is set as the reference voltage level. Thereafter, both the first and second switching elements are turned off, the input voltage applied to the input terminal of the comparator is compared with the set reference voltage level, and the result is output from the output terminal. is there.

  According to the touch sensor of the present invention, the driving method thereof, the display device with the touch sensor, and the electronic device, the touch sensor is configured with a simple configuration by using two electrodes in which capacitance is formed between them. Therefore, high detection sensitivity for external proximity objects and space saving can be realized.

It is a top view showing an example of 1 composition of a display with a touch sensor concerning a 1st embodiment of the present invention. It is sectional drawing for demonstrating one structural example of the electrode of the sensor part shown in FIG. 1, and the electrostatic capacitance formed. It is a block diagram showing an example of 1 composition of a touch sensor. FIG. 4 is a timing waveform diagram illustrating an operation example in a state where there is no external proximity object in the touch sensor illustrated in FIG. 3. FIG. 4 is a block diagram for explaining a state of a self-offset correction period in the sensor unit and the detection unit illustrated in FIG. 3. FIG. 4 is a characteristic diagram for explaining an operation principle of the comparator circuit shown in FIG. 3. FIG. 4 is a block diagram for explaining a state of a touch detection period in the sensor unit and the detection unit illustrated in FIG. 3. FIG. 4 is a timing waveform diagram illustrating an operation example in a state where there is an external proximity object in the touch sensor illustrated in FIG. 3. It is a block diagram showing the example of 1 structure of the touch sensor which concerns on the modification of the 1st Embodiment of this invention. It is a block diagram showing the example of 1 structure of the touch sensor which concerns on the other modification of the 1st Embodiment of this invention. FIG. 11 is a timing waveform diagram illustrating an operation example of the touch sensor illustrated in FIG. 10. It is a block diagram showing the example of 1 structure of the touch sensor which concerns on the further another modification of the 1st Embodiment of this invention. It is a block diagram showing the example of 1 structure of the touch sensor which concerns on the 2nd Embodiment of this invention. FIG. 14 is a timing waveform diagram illustrating an operation example in a state where there is no external proximity object in the touch sensor illustrated in FIG. 13. FIG. 14 is a timing waveform diagram illustrating an operation example of the sensor unit illustrated in FIG. 13. It is a block diagram for demonstrating the state of a touch detection period in the sensor part shown in FIG. FIG. 14 is a timing waveform diagram illustrating an operation example in a state where there is an external proximity object in the touch sensor illustrated in FIG. 13. It is a block diagram showing the example of 1 structure of the touch sensor which concerns on the modification of the 2nd Embodiment of this invention. FIG. 19 is a timing waveform diagram illustrating an operation example of the sensor unit illustrated in FIG. 18. It is a top view showing the external appearance structure of the application example 1 among the touch sensors which applied embodiment. 10 is a plan view and a configuration diagram illustrating an external configuration of an application example 2. FIG. 12 is a plan view and a configuration diagram illustrating an appearance configuration of an application example 3. FIG. 10 is a plan view and a configuration diagram illustrating an external configuration of an application example 4. FIG. It is a perspective view showing the appearance composition of application example 1 among display devices with a touch sensor to which an embodiment is applied. 12 is a perspective view illustrating an appearance configuration of an application example 2. FIG. 12 is a perspective view illustrating an appearance configuration of an application example 3. FIG. 14 is a perspective view illustrating an appearance configuration of an application example 4. FIG. FIG. 10 is a front view, a side view, a top view, and a bottom view illustrating an appearance configuration of application example 5.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The description will be given in the following order.
1. First Embodiment 2. FIG. Second Embodiment 3. FIG. Specific application example 4. Application example to electronic equipment

<1. First Embodiment>
[Configuration example]
(Overall configuration example)
FIG. 1 shows a configuration example of a display device with a touch sensor according to the first embodiment of the present invention. Note that the touch sensor driving method according to the embodiment of the present invention is embodied by the present embodiment, and will be described together. The display device with a touch sensor 1 has a touch sensor arranged outside an effective display area of a display panel using a liquid crystal element as a display element, and an effective display area and a touch detection area of the touch sensor and a peripheral portion thereof. Is provided with another display area. The display device with a touch sensor 1 includes an array substrate 11, a color filter substrate 12, a sensor display unit 14, and a sensor unit 2.

  The array substrate 11 is a substrate on which a TFT (Thin Film Transistor) for driving a liquid crystal element, a transparent pixel electrode, and the like are formed on a transparent substrate. The color filter substrate 12 is a substrate formed by forming a color filter, a transparent common electrode, or the like on a transparent substrate. A liquid crystal layer (not shown) is provided between the array substrate 11 and the color filter substrate 12. A COG (Chip On Glass) 15 is disposed on the array substrate 11. The COG 15 is a chip formed with a circuit for driving a pixel electrode, a common electrode, a TFT, and the like. In addition, the COG 15 is also equipped with a circuit for a touch sensor as will be described later. A terminal portion 16 is provided on the array substrate 11. The terminal portion 16 is for exchanging signals for displaying images and signals for touch sensors with the outside.

  The array substrate 11 and the color filter substrate 12 are provided with an effective display area 13 which is an area for displaying an arbitrary image. In the effective display area 13, the liquid crystal layer is modulated by driving the pixel electrode, the common electrode, and the TFT based on a signal for displaying an image supplied from the outside via the terminal portion 16, thereby displaying the image. Is done.

  The sensor unit 2 is arranged outside the effective display region 13 and detects an external proximity object in the sensor unit 2 and its neighboring region (touch detection region). The sensor unit 2 has two electrodes 21 and 22 as will be described later, and uses the fact that the capacitance related to these electrodes changes in accordance with the presence or absence of the external proximity object, so that the external proximity object It functions to detect.

  FIG. 2 shows a configuration example of the electrodes of the sensor unit 2 using a cross-sectional view together with lines of electric force and capacitance formed, (A) shows a state where there is no external proximity object, B) shows a state where there is an external proximity object. The sensor unit 2 has electrodes 21 and 22. In this example, the electrodes 21 and 22 are arranged on the array substrate 11 so as to be spaced apart from each other, and are made of a transparent conductive film such as ITO (Indium Tin Oxide), for example. The electrodes 21 and 22 are desirably formed on the array substrate as in this example, but may be formed on the color filter substrate. Further, in this figure, for convenience of explanation, the voltage of the electrode 21 (electrode voltage Vel1) is set higher than the voltage of the electrode 22 (electrode voltage Vel2).

  In the state where there is no external proximity object, as shown in FIG. 2A, electric lines of force from the electrode 21 to the electrode 22 are generated, and correspondingly, electrostatic force is generated between the electrode 21 and the electrode 22. A capacitor Cma is formed. Further, a capacitance Cp1 is formed between the electrode 21 and the ground, and a capacitance Cp2 is formed between the electrode 22 and the ground. These electrostatic capacitances Cp1 and Cp2 are parasitic capacitances between the electrode 21 or 22 and wirings arranged in the vicinity.

  On the other hand, in the state where there is an external proximity object (here, a finger), as shown in FIG. 2B, electric lines of force from the electrode 21 to the electrode 22 are generated. It will be blocked. Correspondingly, the electrostatic capacity Cmb between the electrode 21 and the electrode 22 is smaller than the electrostatic capacity Cma in the state where there is no external proximity object. On the other hand, lines of electric force are generated between the electrodes 21 and 22 and the external proximity object, respectively, and a capacitance Cf1 is newly formed between the electrode 21 and the ground via the external proximity object, A capacitance Cf2 is newly formed between the terminal 22 and the ground via the external proximity object. Therefore, the capacitance between the electrode 21 and the ground is Cp1 + Cf1, and the capacitance between the electrode 22 and the ground is Cp2 + Cf2. That is, the capacitance between the electrode 21 and the ground and the capacitance between the electrode 22 and the ground in the state where there is an external proximity object are larger than those in the case where there is no external proximity object.

  As shown in FIG. 1, the detection unit 3 is disposed on the array substrate 11 near the sensor unit 2. The change in capacitance in the sensor unit 2 described above is detected by the detection unit 3.

  The sensor display unit 14 is for displaying on the sensor unit 2 and its peripheral part, and has a display element (in this example, a liquid crystal element) having the same structure as the effective display region 13. Similar to the effective display area 13, the sensor display unit 14 performs display based on a signal for displaying an image supplied from the outside via the terminal unit 16. The sensor display unit 14 and the sensor unit 2 constitute a display unit 17 with a touch sensor.

  Note that a backlight (not shown) is disposed under the array substrate 11 and emits light toward the array substrate 11. The light is modulated by the liquid crystal layer, whereby an image is displayed on the effective display area 13 and the sensor display unit 14, and the display device with a touch sensor 1 functions as a liquid crystal display device.

(Touch sensor circuit configuration example)
Next, focusing on the touch sensor function of the display device with a touch sensor 1, an example of the circuit configuration will be described.

  FIG. 3 illustrates a circuit configuration example of the touch sensor. In addition to the sensor unit 2 and the detection unit 3 described above, the touch sensor 10 includes a touch determination unit 4, a control signal generation unit 5, and a timing control circuit 6.

  The sensor unit 2 includes switching elements SW1 to SW4 in addition to the electrodes 21 and 22 described above. In FIG. 3, the capacitance between the electrode 21 and the electrode 22 (capacitance between the electrodes) is the capacitance Cma (FIG. 2A) when there is no external proximity object and the external proximity object. As a general term for the capacitance Cmb (FIG. 2B) when present, the capacitance Cm is indicated. In addition, the capacitance (grounding capacitance) between the electrodes 21 and 22 and the ground is the static capacitance Cp1 and Cp2 (FIG. 2A) when there is no external proximity object and the static when there is an external proximity object. Capacitances Cp1 + Cf1, Cp2 + Cf2 (FIG. 2 (B)) are collectively indicated by capacitances Cg1, Cg2, respectively.

  The switching elements SW1 to SW3 apply a voltage to the electrodes 21 and 22 in a time-sharing manner. The switching element SW1 is disposed between the ground (GND) and the electrode 21, is on / off controlled by the SW control signal SC, and applies 0V to the electrode 21 in a time-sharing manner. The switching element SW2 is disposed between the voltage VDD and the electrode 21, is on / off controlled by the SW control signal SCB, and applies the voltage VDD to the electrode 21 in a time division manner. The switching element SW3 is disposed between the ground (GND) and the electrode 22, is on / off controlled by the SW control signal SC, and applies 0 V to the electrode 22 in a time-sharing manner. As will be described later, the SW control signals SC and SCB are logic signals supplied by the control signal generator 5, and the SW control signal SCB is obtained by inverting the SW control signal SC. Thereby, the voltage VDD or 0V is applied to at least one of the electrodes 21 and 22 in a time-sharing manner. The switching elements SW1 to SW3 are each formed on the array substrate 11 with TFTs. As the switching elements SW1 and SW3, for example, n-channel MOS (Metal Oxide Semiconductor) type TFTs can be used, and as the switching element SW2, for example, p-channel MOS type TFTs can be used.

  As will be described later, the switching element SW4 connects the sensor unit 2 and the detection unit 3 at a predetermined timing so as to transmit information about the presence or absence of an external proximity object in the touch detection region to the detection unit 3. Have. The switching element SW4 is disposed between the electrode 22 and the capacitive element Cstr (described later) of the detection unit 3, and is turned on / off by the SW control signal SCB. As a result, an electric charge is generated between the electrostatic capacitances Cm and Cg2 of the sensor unit 2 and the capacitive element Cstr of the detection unit 3 every time the switching element SW4 is turned on based on the operation principle of a so-called switched capacitor. Is exchanged. Note that the switching element SW4 is formed by a TFT on the array substrate 11, and for example, an analog switch (transmission gate) can be used.

  The detection unit 3 is a circuit that accumulates charges supplied from the sensor unit 2 and outputs a signal as a detection signal Vdet when the accumulated amount exceeds a certain amount. As shown in FIG. Arranged on the array substrate 11 near the portion 2. The detection unit 3 includes a capacitive element Cstr and a comparator circuit 30.

  The capacitive element Cstr exchanges charges with the sensor unit 2 every time the switching element SW4 is turned on, and accumulates the charges. A switching element SW5 is connected in parallel to the capacitive element Cstr. The switching element SW5 is on / off controlled by the SW control signal SA. The SW control signal SA is a logic signal supplied by a control signal generation unit 5 (described later), and is used for discharging the capacitive element Cstr. Specifically, as will be described later, prior to accumulation of charge in the capacitive element Cstr, the switching element SW5 is turned on by the SW control signal SA, and the charge accumulated in the capacitive element Cstr is discharged. ing. The switching element SW5 is formed by a TFT on the array substrate 11, and for example, an n-channel MOS (Metal Oxide Semiconductor) type TFT can be used. The SW control signal SA is also used for an offset adjustment function of the comparator circuit 30 described later.

  A switching element SW8 is inserted between the capacitive element Cstr and the comparator circuit 30, and on / off control is performed by the SW control signal SB. The SW control signal SB is a logic signal supplied by a control signal generation unit 5 (described later). The switching element SW8 is formed on the array substrate 11 with TFTs, and for example, an analog switch (transmission gate) can be used.

  The comparator circuit 30 monitors the charge accumulated in the capacitive element Cstr as the accumulated voltage Vstr via the switching element SW8, compares the voltage level with a predetermined reference voltage Vref, and outputs the comparison result. Circuit. The comparator circuit 30 includes inverter circuits 31 and 32, a capacitive element Ccomp, and switching elements SW6 and SW7. The switching element SW6 is a switch that supplies the reference voltage Vref to the input of the comparator circuit 30, and is controlled to be turned on / off by the SW control signal SA. The capacitive element Ccomp is inserted between the input of the comparator circuit 30 and the input of the inverter circuit 31. The inverter circuit 31 is a circuit that inverts and outputs an input signal. The switching element SW7 is inserted between the input and output of the inverter circuit 31, and ON / OFF control is performed by the SW control signal SA. The inverter circuit 32 is a circuit that inverts the signal supplied from the inverter circuit 31 and outputs it as an output signal of the comparator circuit 30. With this configuration, the comparator circuit 30 sets the reference voltage Vref to the threshold voltage Vthc of the comparator circuit 30 (self-offset adjustment) when the switching elements SW6 and SW7 are turned on. When the switching elements SW6 and SW7 are turned off, they function to compare the input of the comparator circuit 30 (comparator input voltage Vcomp) with this threshold voltage Vthc. The switching elements SW6 and SW7 and the inverter circuits 31 and 32 are formed on the array substrate 11 by TFTs. As the switching elements SW6 and 7, for example, analog switches (transmission gates) can be used, and as the inverter circuits 31 and 32, for example, a CMOS (Complementary Metal Oxide Semiconductor) inverter circuit can be used.

  Based on the detection signal Vdet supplied from the detection unit 3, the touch determination unit 4 starts to accumulate charges in the capacitive element Cstr of the detection unit 3, and then has a certain amount of accumulated charge in the capacitive element Cstr. By detecting the time to reach the amount (accumulation time tstr), the presence / absence of an external proximity object is detected. The touch determination unit 4 includes a time measurement circuit 41, a determination circuit 42, and a memory 43.

  The time measurement circuit 41 is a circuit that detects the accumulation time tstr based on the detection signal Vdet supplied from the detection unit 3. For example, a method of counting the number of pulses of an internally generated clock signal or an externally supplied clock signal (not shown) can be used to measure the accumulation time tstr.

  The determination circuit 42 is a circuit that detects the presence or absence of an external proximity object by comparing the accumulation time tstr detected by the time measurement circuit 41 with a predetermined reference time tref. As the reference time tref, for example, the accumulation time tstr with and without an external proximity object is measured in advance, and an intermediate value of the accumulation time tstr under these two conditions can be used. As will be described later, this operation principle uses the fact that the accumulation time tstr changes depending on the presence or absence of an external proximity object.

  The memory 43 holds a determination result regarding the presence / absence of an external proximity object in the determination circuit 42 and outputs it as a touch determination output Vout. The determination result in the memory is updated every time the determination circuit 42 determines.

  The control signal generation unit 5 generates SW control signals SA, SB, SC, and SCB and supplies them to the sensor unit 2 and the detection unit 3. The control signal generation unit 5 includes a control signal generation circuit 50 and an inverter circuit 51. The control signal generation circuit 50 generates the SW control signals SA, SB, SC based on the control signal supplied from the timing control circuit 6 described later, and supplies the SW control signals SA, SB to the detection unit 3, The SW control signal SC is supplied to the sensor unit 2. The inverter circuit 51 inverts the SW control signal SC generated by the control signal generation circuit 50 and outputs it as the SW control signal SCB and supplies it to the sensor unit 2.

  The timing control circuit 6 is a circuit that generates and supplies a control signal instructing operation timing to the touch determination unit 4 and the control signal generation unit 5.

  The touch determination unit 4, the control signal generation unit 5, and the timing control circuit 6 are mounted on the COG 15 in FIG. Alternatively, it may be formed on the array substrate 11 by TFT instead.

  Here, the electrode 21 corresponds to a specific example of “first electrode” in the present invention, and the electrode 22 corresponds to a specific example of “second electrode” in the present invention. The capacitive element Cstr corresponds to a specific example of “a capacitive element” in the present invention. The control signal generator 5 and the switching elements SW1 to SW4 correspond to a specific example of “drive controller” in the present invention. The detection unit 3 and the touch determination unit 4 correspond to a specific example of “detection unit” in the present invention. The sensor display unit 14 corresponds to a specific example of “another display unit” in the present invention.

  The switching element SW6 corresponds to a specific example of “first switching element” in the present invention, and the switching element SW7 corresponds to a specific example of “second switching element” in the present invention. The capacitive element Ccomp corresponds to a specific example of “another capacitive element” in the present invention. The inverter circuit 31 corresponds to a specific example of “an inverting circuit” in the present invention.

[Operation and Action]
Next, the operation and action of the display device with a touch sensor 1 according to the present embodiment will be described.

(Overview of overall operation)
The light emitted from the backlight under the array substrate 11 is incident on the liquid crystal layer between the array substrate 11 and the color filter substrate 12. The COG 15 drives the pixel electrodes and TFTs of the array substrate 11 and the common electrode of the color filter substrate 12 to modulate the liquid crystal layer. The intensity of the incident light is modulated by this liquid crystal layer. As a result, an image is displayed on the effective display area 13 and the sensor display unit 14.

  Based on the SW control signals SC and SCB supplied from the control signal generation unit 5, the sensor unit 2 exchanges charges with the capacitive element Cstr of the detection unit 3 based on the so-called switched capacitor operating principle. And charge is accumulated in the capacitive element Cstr. The comparator circuit 30 of the detector 3 monitors the charge accumulated in the capacitive element Cstr as the accumulated voltage Vstr, compares the voltage level with the reference voltage Vref, and outputs the comparison result as a detection signal Vdet. The time measuring circuit 41 of the touch determination unit 4 detects the accumulation time tstr based on the detection signal Vdet. The determination circuit 42 determines whether or not there is an external proximity object by comparing the accumulation time tstr with a predetermined reference time tref. The memory 43 holds the determination result.

(Operation of the touch sensor 10 when there is no external proximity object)
First, an operation example when there is no external proximity object in the touch detection area of the touch sensor 10 will be described.

  FIG. 4 is a timing chart of the touch sensor 10 according to the present embodiment, and represents an example when there is no external proximity object. 4A shows the voltage waveform of the SW control signal SA, FIG. 4B shows the voltage waveform of the SW control signal SB, FIG. 4C shows the voltage waveform of the SW control signal SC, and FIG. The voltage waveform of SW control signal SCB is shown. 4A to 4D show how the voltage levels of the SW control signals SA, SB, SC, and SCB that are logic signals periodically change between a low level and a high level. Yes. The switching elements SW1 to SW8 controlled by the SW control signals SA, SB, SC, and SCB are turned on when the voltage level of the logic signal is high and are turned off when the voltage level of the logic signal is low. Shall be. 4, (E) shows the waveform of the electrode voltage Vel1 of the electrode 21, (F) shows the waveform of the electrode voltage Vel2 of the electrode 22, (G) shows the waveform of the accumulated voltage Vstr, and (H ) Shows the waveform of the comparator input voltage Vcomp, and (I) shows the waveform of the detection signal Vdet.

  First, in the self-offset correction period T0, the touch sensor 10 performs self-offset correction of the comparator circuit 30 and discharges the capacitive element Cstr. Then, in the touch detection period T1, the sensor unit 2 performs the operation of the switched capacitor, thereby accumulating charges in the capacitive element Cstr. When the accumulated charge reaches a predetermined amount, the detection signal Vdet changes. The touch determination unit 4 detects the presence / absence of an external proximity object by detecting the accumulation time tstr based on the detection signal Vdet. Thereafter, after the end period T2, the process returns to the self-offset correction period T0. The touch sensor 10 continuously detects the presence or absence of an external proximity object by repeating the cycle of the periods T0 to T2.

(Self offset correction period T0)
First, the detection unit 3 performs self-offset correction of the comparator circuit 30 and discharges the capacitive element Cstr. Specifically, the control signal generation unit 5 changes the voltage of the SW control signal SA from the low level to the high level during the period in which the voltage of the SW control signal SB is low (FIG. 4A). . Accordingly, the switching element SW5 is turned on, the capacitor element Cstr is discharged, and the accumulated voltage Vstr becomes 0 V (FIG. 4G). Further, the switching elements SW6 and SW7 are turned on, and the threshold voltage Vthc of the comparator circuit 30 is corrected.

  Next, correction of the threshold voltage Vthc of the comparator circuit 30 will be described.

  FIG. 5 shows the states of the sensor unit 2 and the detection unit 3 during the self-offset correction period T0. The switching element SW6 is turned on, and the reference voltage Vref is applied to the input of the comparator circuit 30 (the terminal on the left side of the capacitive element Ccomp in FIG. 5). On the other hand, the switching element SW7 is also in an on state, thereby forming a negative feedback path in the inverter circuit 31.

  FIG. 6A shows an input / output characteristic example of the inverter circuit 31 alone. The horizontal axis represents the input voltage Vi of the inverter circuit 31, and the vertical axis represents the output voltage Vo of the inverter circuit 31. A characteristic W1 is an example of input / output characteristics of the inverter circuit 31 alone, and shows a state in which the output voltage Vo is inverted with the threshold voltage Vthi of the inverter circuit 31 as a boundary. When the switching element SW7 is turned on, the input voltage Vi becomes equal to the output voltage Vo due to negative feedback (Vi = Vo). At this time, the inverter circuit 31 is such that the input / output characteristic W1 of the inverter circuit 31 alone and the characteristic W2 indicating the negative feedback relational expression Vi = Vo are compatible (intersect) with the point P1 as its operating point. Operate. That is, the voltage Vi at the input of the inverter circuit 31 (the right terminal of the capacitive element Ccomp in FIG. 5) is equal to the threshold voltage Vthi of the inverter circuit 31.

  Thus, in the self-offset correction period T0, the reference voltage Vref and the threshold voltage Vthi of the inverter circuit 31 are applied to both ends of the capacitive element Ccomp. The potential difference ΔVcomp = Vref−Vthi across the capacitor Ccomp is maintained in the touch detection period T1 following the self-offset correction period T0 due to the switching element SW7 being turned off, as will be described later. It will be. That is, the capacitive element Ccomp functions to shift the stored voltage Vstr, which is the input voltage of the comparator circuit 30, by the level of the potential difference ΔVcomp and supply it to the input of the inverter circuit 31.

  FIG. 6B illustrates an example of input / output characteristics of the comparator circuit 30 in the touch detection period T1. The horizontal axis represents the input voltage Vcomp of the comparator circuit 30, and the vertical axis represents the voltage of the detection signal Vdet which is the output voltage of the comparator circuit 30. The input / output characteristic (characteristic W3) of the comparator circuit 30 shows how the detection signal Vdet changes with the reference voltage Vref as a boundary. This characteristic is realized for the following reason. That is, for example, when the input voltage Vcomp of the comparator circuit 30 is the same voltage as the reference voltage Vref, Vthi (= Vref−ΔVcomp) is applied to the input voltage Vi of the inverter circuit 31 due to the level shift caused by the capacitance element Ccomp. Supplied. The inverter circuit 31 is inverted using this voltage as a boundary (FIG. 6A), and the inverter circuit 32 at the subsequent stage of the inverter circuit 31 is also inverted correspondingly. Therefore, as shown in FIG. 6B, the input / output characteristics of the comparator circuit 30 change the voltage of the detection signal Vdet, which is the output voltage, with the reference voltage Vref as a boundary. This means that the reference voltage Vref is set to the threshold voltage Vthc of the comparator circuit 30 (self-offset adjustment).

  Thus, after the self-offset correction of the comparator circuit 30 and the discharge of the capacitive element Cstr are completed, the control signal generator 5 changes the voltage of the SW control signal SA from a high level to a low level (FIG. 4 ( A)). Thus, the self-offset correction period T0 ends. The operation in the self-offset correction period T0 is performed in the same manner without being affected by the presence or absence of an external proximity object.

(Touch detection period T1)
Next, the sensor unit 2 starts accumulation of electric charges in the capacitive element Cstr by performing the operation of the switched capacitor. Specifically, first, the control signal generator 5 changes the voltage of the SW control signal SB from a low level to a high level during a period in which the voltage of the SW control signal SA is low (FIG. 4B )). As a result, the switching element SW8 is turned on, and a voltage corresponding to the accumulated charge of the capacitive element Cstr is supplied to the input of the comparator circuit 30 as the accumulated voltage Vstr. That is, the accumulated voltage Vstr becomes 0 V with the start of the touch detection period T1 (FIG. 4G). Further, the comparator circuit 30 outputs a low level (0 V) because the inputted storage voltage Vstr is lower than the reference voltage Vref (FIG. 4 (I)). On the other hand, at the same time, the control signal generator 5 starts to periodically change the voltages of the SW control signals SC and SCB (FIGS. 4C and 4D). That is, simultaneously with the start of the touch detection period T1, first, the control signal generation unit 5 changes the SW control signal SC from a low level to a high level (FIG. 4C), and also changes the SW control signal SCB from a high level. The state is changed to a low level (FIG. 4D), and the state is maintained for a certain time (first period T11). Thereafter, the control signal generator 5 changes the SW control signal SC from the high level to the low level (FIG. 4C), and changes the SW control signal SCB from the low level to the high level (FIG. 4D). The state is maintained for a certain period of time (second period T12). The control signal generator 5 generates and outputs the SW control signals SC and SCB so as to alternately repeat the first period T11 and the second period T12 during the touch detection time T1.

  FIG. 7 shows the states of the sensor unit 2 and the detection unit 3 in the touch detection period T1, (A) shows the state in the first period T11, and (B) shows the state in the second period T12. Indicates.

  In the first period T11, as illustrated in FIG. 7A, the switching elements SW1 and SW3 are in the on state, and the switching elements SW2 and SW4 are in the off state. As a result, 0V is applied (initialized) to the electrodes 21 and 22 (FIGS. 4E and 4F).

  In the second period T12, as shown in FIG. 7B, the switching elements SW2 and SW4 are in the on state, and the switching elements SW1 and SW3 are in the off state. Accordingly, the voltage VDD is applied to the electrode 21 (FIG. 4E). At this time, some of the charges of the electrostatic capacitances Cm and Cg2 flow into the capacitive element Cstr as the transient accumulated current Istr via the switching element SW4. Then, the storage voltage Vstr rises by the amount of charge that has flowed in as a transient storage current Istr (FIG. 4G).

  Thereafter, the first period T11 and the second period T12 are alternately repeated, so that the switching element SW4 is turned on in the second period T12 based on the so-called switched capacitor operating principle. Each time, charge is accumulated in the capacitor Cstr, and accordingly, the accumulated voltage Vstr rises (FIG. 4G).

  When the accumulated voltage Vstr (comparator input voltage Vcomp) exceeds the voltage level of the reference voltage Vref, the comparator circuit 30 outputs a high level voltage as a comparison result (detection signal Vdet) (FIG. 4). (I)). That is, the detection signal Vdet is the time (accumulation time tstr) until the charge accumulation amount of the capacitance element Cstr reaches a certain amount (Cstr × Vref) after the accumulation of the charge in the capacitance element Cstr is started. Maintain a low level. The touch determination unit 4 detects the accumulation time tstr based on the detection signal Vdet, and detects the presence or absence of an external proximity object using this.

(End period T2)
Finally, the sensor unit 2 finishes the operation of the switched capacitor and prepares for the next cycle. Specifically, first, the control signal generator 5 stops the periodic change of the SW control signals SC and SCB (FIGS. 4C and 4D). Then, the control signal generation unit 5 changes the voltage of the SW control signal SB from the high level to the low level (FIG. 4B). As a result, the switching element SW8 is turned off, and the capacitive element Cstr and the comparator circuit 30 are disconnected.

  Thereafter, after a predetermined period has elapsed, the touch sensor 10 proceeds to the self-offset correction period T0 described above. The touch sensor 10 operates so as to repeat the cycle of the period T0 to T2.

(Operation of the touch sensor 10 when there is an external proximity object)
Next, an operation example of the touch detection period T1 when there is an external proximity object in the touch detection area of the touch sensor 10 will be described. Since the operations in the self-offset correction period T0 and the end period T2 are the same regardless of the presence or absence of an external proximity object, the description thereof is omitted.

  Even when there is an external proximity object, the sensor unit 2 and the detection unit 3 operate as shown in FIG. 7 in the touch detection period T1 in the same manner as when there is no external proximity object. However, the transient accumulated current Istr in the second period T12 varies depending on the presence or absence of an external proximity object.

  As shown in FIG. 2, the capacitances Cm, Cg1, and Cg2 change depending on the presence or absence of an external proximity object in the touch detection area of the touch sensor 10. That is, regarding the capacitance Cm, the value when there is an external proximity object (capacitance Cmb) is smaller than the value when there is no external proximity object (capacitance Cma). Regarding the capacitances Cg1 and Cg2, values when there are external proximity objects (Cp1 + Cf1, Cp2 + Cf2) are larger than values when there are no external proximity objects (Cp1, Cp2). As a result, the transient accumulated current Istr when there is an external proximity object is smaller than when there is no external proximity object.

  FIG. 8 is an example of a timing diagram of the touch sensor 10 according to the present embodiment, and represents an example when there is an external proximity object. 8A shows the voltage waveform of the SW control signal SA, FIG. 8B shows the voltage waveform of the SW control signal SB, FIG. 8C shows the voltage waveform of the SW control signal SC, and FIG. The voltage waveform of the SW control signal SCB is shown, (E) shows the waveform of the electrode voltage Vel1 of the electrode 21, (F) shows the waveform of the electrode voltage Vel2 of the electrode 22, and (G) shows the waveform of the accumulated voltage Vstr. (H) shows the waveform of the comparator input voltage Vcomp, and (I) shows the waveform of the detection signal Vdet.

  In the case where there is an external proximity object, in the second period T12, the transient accumulated current Istr decreases, the amount of charge accumulated in the capacitive element Cstr into which it flows, and accordingly, the amount of increase in the accumulated voltage Vstr also increases. Decrease. In the touch detection period T1, the first period T11 and the second period T12 are alternately repeated, so that the accumulated voltage Vstr increases every second period T12, but there is an external proximity object. In this case, the changing speed of the accumulated voltage Vstr becomes slow. Due to this, when there is an external proximity object, the accumulation time tstr becomes longer (FIG. 8I).

  As described above, the accumulation time tstr varies depending on the presence or absence of an external proximity object. Accordingly, the determination circuit 42 of the touch determination unit 4 can determine the presence / absence of an external proximity object by comparing the accumulation time tstr with a predetermined reference time tref.

[effect]
As described above, in the present embodiment, the presence / absence of an external proximity object is detected using the change in the capacitance Cm between the two electrodes 21 and 22, so the capacitance of one electrode Compared with the case of using the change, for example, the influence of the conductive material in the peripheral portion such as the wiring on the array substrate 11 can be reduced, and downsizing and improvement in sensitivity can be realized.

  In the present embodiment, since the detection unit 3 is arranged in the vicinity of the sensor unit 2, the parasitic capacitance of the wiring between the sensor unit 2 and the detection unit 3 is reduced, and noise caused by crosstalk is mixed. Can also be minimized. As a result, the presence or absence of an external proximity object is detected based on a minute signal supplied from the sensor unit 2 having a simple structure without using a complicated sensor structure with high sensitivity and without providing an amplifier. Thus, downsizing and cost reduction can be realized.

  In the present embodiment, a switched capacitor is used as a method for detecting an external proximity object, and a comparator circuit 30 with a self-offset correction function is used as a detection circuit. As a result, resistance to instantaneous noise and element variations caused by the TFT manufacturing process is increased, and a small and simple circuit configuration can be realized.

  In the present embodiment, since the touch sensor is configured using the sensor unit and the detection unit having a simple configuration as described above, space can be saved, and a display device with a touch sensor is configured using the touch sensor. In this case, a display device with a touch sensor having a narrow frame area can be realized.

  Furthermore, in this embodiment, when a display device with a touch sensor is configured, the sensor unit and the detection unit are formed on the same array substrate as the liquid crystal display device (effective display area), and other necessary circuits are provided. Since it is mounted on the COG, the number of parts can be reduced, the cost can be reduced, and the frame area can be narrowed.

[Modification 1-1]
In the above embodiment, one end of the switching elements SW1 and SW3 is connected to the ground (GND), and one end of the switching element SW2 is connected to the voltage VDD. However, the present invention is not limited to this. In the above embodiment, one end of the capacitive element Cstr is connected to the ground (GND). However, the present invention is not limited to this. For example, as shown in FIG. 9, one end of the switching elements SW1 and SW3 is connected to the voltage VDD, one end of the switching element SW2 is connected to the ground (GND), and one end of the capacitive element Cstr is connected to the voltage VDD. You may do it. In this example, when the operation of the switched capacitor is performed in the touch detection period T1, the accumulated voltage Vstr operates so as to gradually decrease from the voltage VDD. As a result, the detection signal Vdet, which is the output of the comparator circuit 30, has a waveform inverted from that of the above embodiment. The time measurement circuit 41B of the touch determination unit 4B is a circuit that measures the accumulation time tstr based on the inverted waveform. In this case, for example, p-channel MOS type TFTs can be used as the switching elements SW1, SW3, and SW5, and for example, n-channel MOS type TFTs can be used as the switching element SW2. Others are the same as in the above embodiment.

[Modification 1-2]
In the above embodiment, the change speed of the accumulated voltage Vstr in the touch detection period T1 is measured as the time (accumulation time tstr) until the accumulated voltage Vstr reaches a certain value, but instead, the change of the accumulated voltage Vstr. The speed may be measured as a voltage value of the storage voltage Vstr at a predetermined timing after the start of storage. Hereinafter, this modification will be described in detail.

  FIG. 10 illustrates a configuration example of the touch sensor 10C according to the present modification. Note that parts that are substantially the same as those of the touch sensor 10 according to the above-described embodiment are denoted by the same reference numerals, and description thereof is omitted as appropriate.

  The touch sensor 10C includes a detection unit 3C, a touch determination unit 4C, a control signal generation unit 5C, and a timing control circuit 6C. The detection unit 3C includes an S / H (Sample and Hold) circuit 33 and an ADC (Analog to Digital Converter) circuit 34, and the storage voltage Vstr based on the read control signal SD supplied from the control signal generation unit 5C. Is converted into a digital signal by the ADC circuit 34, and the result is output as a detection code Cdet. Here, the bit width of the digital output of the ADC circuit is 2 bits for convenience of explanation. However, the bit width is not limited to this. For example, the bit width is increased to 4 bits or 8 bits and stored with higher accuracy. The voltage Vstr may be A / D converted. The touch determination unit 4C includes a determination circuit 42C. The determination circuit 42C compares the detection code Cdet supplied from the detection unit 3C with a predetermined reference code Cref, thereby detecting an external proximity object. The presence or absence is detected.

  FIG. 11 is a timing chart of the touch sensor 10C according to the present embodiment. 11A shows the voltage waveform of the SW control signal SA, FIG. 11B shows the voltage waveform of the SW control signal SC, FIG. 11C shows the voltage waveform of the SW control signal SCB, and FIG. The voltage waveform of the read control signal SD is shown, (E) shows the waveform of the electrode voltage Vel1 of the electrode 21, (F) shows the waveform of the electrode voltage Vel2 of the electrode 22, and (G) shows the waveform of the accumulated voltage Vstr. (H) shows the waveform of the ADC input voltage Vadc, and (I) shows the waveform of the detection signal Vdet. The operation of the touch sensor 10C is the same as that of the touch sensor 10 according to the present embodiment with respect to the sensor unit 2 (FIGS. 11B, 11C, 11E and 11G).

  First, in the preparation period T0c, the touch sensor 10C discharges the capacitive element Cstr and initializes the state of the S / H circuit 33 based on the SW control signal SA (FIG. 11 (H)). Thereafter, in the touch detection period T1c, as in the touch sensor 10 according to the present embodiment, the sensor unit 2 operates as a switched capacitor, thereby accumulating charges in the capacitive element Cstr and accumulating correspondingly. The voltage Vstr increases (FIG. 11 (G)). Then, after the touch detection period T1 is started, a pulse having a certain width is supplied as a read control signal SD at a timing after a certain period of time, and based on this, the S / H circuit 33 generates the accumulated voltage Vstr. Sampling is performed, and then the state is maintained (FIG. 11H). The ADC circuit 34 A / D converts this voltage and outputs it as a detection code Cdet (FIG. 11 (I)). The touch determination unit 4C detects the presence or absence of an external proximity object based on the detection code Cdet. Thereafter, the touch sensor 10C returns to the preparation period T0c. The touch sensor 10 continuously detects the presence or absence of an external proximity object by repeating the cycle of the periods T0 to T2.

  Unlike the touch sensor 10 according to the present embodiment, the touch sensor 10C according to the present modification detects the presence or absence of an external proximity object by measuring the accumulated voltage Vstr at a predetermined timing. Therefore, it is possible to detect not only whether there is an external proximity object but also the degree of proximity of the external proximity object to the touch detection area. In particular, when the ADC circuit 34 having a conversion characteristic with higher resolution is used, the stored voltage Vstr can be measured with higher accuracy, so that the degree of proximity can be detected with higher accuracy.

  A similar operation can be realized by the touch sensor 10D shown in FIG. The touch sensor 10D is a touch sensor 10C in which a latch circuit 35 is provided behind the ADC circuit 34 instead of the S / H circuit 33 disposed in front of the ADC circuit 34, and the other configurations are the same. is there. The latch circuit 35 is latched by the read control signal SD and is initialized by the SW control signal SA. In other words, the touch sensor 10C and the touch sensor 10D may arrange a functional block that samples and maintains the accumulated voltage Vstr at a predetermined timing in the previous stage of the ADC circuit 34 (S / H circuit 33 in FIG. 10). The difference is whether it is arranged in the subsequent stage (latch circuit 35 in FIG. 12), which is essentially the same. Therefore, the touch sensor 10D can also detect the degree of proximity of the external proximity object to the touch detection area.

<2. Second Embodiment>
Next, a display device with a touch sensor according to a second embodiment of the present invention will be described. In the present embodiment, in the touch sensor constituting the display device with a touch sensor shown in FIG. 1, the driving method of the electrodes 21 and 22 of the sensor unit is different from that in the first embodiment. That is, in the first embodiment (FIG. 3), the touch sensor 10 that operates using only the electrode 21 as the drive electrode is configured using the control signal generation unit 5 and the sensor unit 2, but instead, In the present embodiment, a touch sensor 90 that operates using both the electrodes 21 and 22 as drive electrodes is configured using the control signal generation circuit 8 and the sensor unit 7. Other configurations are the same as those of the first embodiment (FIG. 3). In addition, the same code | symbol is attached | subjected to the substantially same component as the display apparatus with a touch sensor which concerns on the said 1st Embodiment, and description is abbreviate | omitted suitably.

[Configuration example]
(Touch sensor circuit configuration example)
FIG. 13 illustrates a circuit configuration example of the touch sensor 90. The touch sensor 90 includes a sensor unit 7 and a control signal generation unit 8.

  The sensor unit 7 includes electrodes 21 and 22 and switching elements SW11 to SW14.

  The switching elements SW11 to SW13 apply voltages to the electrodes 21 and 22 in a time division manner. The switching element SW11 is disposed between the voltage VDD and the electrode 21, is on / off controlled by the SW control signal SC11, and applies the voltage VDD to the electrode 21 in a time division manner. The switching element SW12 is disposed between the ground (GND) and the electrode 21, is on / off controlled by the SW control signal SC12, and applies 0V to the electrode 21 in a time-sharing manner. The switching element SW13 is disposed between the voltage VDD and the electrode 22, is on / off controlled by the SW control signal SC13, and applies the voltage VDD to the electrode 22 in a time division manner. As will be described later, the SW control signals SC11 to SC13 are logic signals supplied by the control signal generation circuit 8, and the voltage VDD or 0V is applied to at least one of the electrodes 21 and 22 in a time-sharing manner. It is supposed to be. The switching elements SW11 to SW13 are each formed on the array substrate 11 by TFTs. As the switching elements SW11 and SW13, for example, a p-channel MOS type TFT can be used, and as the switching element SW12, for example, an n-channel MOS type TFT can be used.

  As will be described later, the switching element SW14 has a function of connecting the sensor unit 7 and the detection unit 3 at a predetermined timing to transmit information regarding the presence or absence of an external proximity object in the touch detection region to the detection unit 3. Have. The switching element SW14 is disposed between the electrode 22 and the capacitive element Cstr of the detection unit 7, and ON / OFF control is performed by the SW control signal SC14. As a result, an electric charge is generated between the electrostatic capacitances Cm and Cg2 of the sensor unit 7 and the capacitive element Cstr of the detection unit 3 every time the switching element SW14 is turned on based on a so-called switched capacitor operating principle. Is exchanged. The SW control signal SC14 is a logic signal supplied by a control signal generation circuit 8 (described later). Note that the switching element SW14 is formed by a TFT on the array substrate 11, and an analog switch (transmission gate) can be used, for example.

  The control signal generation circuit 8 generates the SW control signals SA, SB, SC11 to SC14 based on the timing control circuit 6, and supplies the SW control signals SA and SB to the detection unit 3, and the SW control signals SC11 to SC14. Is supplied to the sensor unit 7.

[Operation and Action]
(Operation of the touch sensor 90 when there is no external proximity object)
FIG. 14 is a timing chart of the touch sensor 90 according to the present embodiment, and represents an example when there is no external proximity object. 14A shows the voltage waveform of the SW control signal SA, FIG. 14B shows the voltage waveform of the SW control signal SB, FIG. 14C shows the voltage waveform of the SW control signal SC11, and FIG. The voltage waveform of SW control signal SC12 is shown, (E) shows the voltage waveform of SW control signal SC13, and (F) shows the voltage waveform of SW control signal SC14. FIGS. 13A to 13F show how the voltage levels of the SW control signals SA, SB, SC11 to SC14 that are logic signals periodically change between a low level and a high level. Yes. For convenience of explanation, the switching elements SW1 to SW8 controlled by the SW control signals SA, SB, SC11 to SC14 are turned on when the voltage level of the logic signal is high, and are turned off when the voltage level is low. Shall be. In FIG. 14, (G) shows the waveform of the electrode voltage Vel1 of the electrode 21, (H) shows the waveform of the electrode voltage Vel2 of the electrode 22, (I) shows the waveform of the accumulated voltage Vstr, and (J ) Shows the waveform of the comparator input voltage Vcomp, and (K) shows the waveform of the detection signal Vdet.

  The operation of the touch sensor 90 in the present embodiment differs from the touch detection period T1 (FIG. 4) of the first embodiment only in the operation of the touch detection period T1e. That is, the operations in the self-offset period T0 and the end period T2 are the same as the corresponding operations (periods T0 and T2 in FIG. 4) of the touch sensor 10 in the first embodiment.

(Touch detection period T1e)
In the touch detection period T1e, the sensor unit 7 starts to accumulate charges in the capacitive element Cstr by performing the operation of the switched capacitor. Specifically, first, the control signal generation circuit 8 changes the voltage of the SW control signal SB from a low level to a high level during a period in which the voltage of the SW control signal SA is low (FIG. 14B )). As a result, the switching element SW8 is turned on, and the voltage of the capacitive element Cstr is supplied to the input of the comparator circuit 30 as the accumulated voltage Vstr. Since the capacitive element Cstr is discharged in the self-offset correction period T0 prior to the touch detection period T1e, the accumulated voltage Vstr becomes 0 V with the start of the touch detection period T1e (FIG. 14 (I)). Furthermore, the comparator circuit 30 outputs a low level (0 V) because the input storage voltage Vstr (comparator input voltage Vcomp) is lower than the reference voltage Vref (FIG. 14 (K)). On the other hand, at the same time, the control signal generation circuit 8 starts to periodically change the voltages of the SW control signals SC11 to SC14 (FIGS. 14C to 14F). That is, first, the control signal generation circuit 8 changes the SW control signals SC11 and SC13 from a low level to a high level (FIGS. 14C and 14E), and also changes the SW control signals SC12 and SC14 from a high level to a low level. The level is changed (FIGS. 14D and 14F), and the state is maintained for a certain time (first period T11e). Next, the control signal generation circuit 8 changes the SW control signals SC11 and SC13 from the high level to the low level (FIGS. 14C and 14E), and changes the SW control signal SC12 from the low level to the high level. (FIG. 14D) and the state is maintained for a certain time (second period T12e). Thereafter, the control signal generation circuit 8 changes the SW control signal SC13 from the low level to the high level (FIG. 14E), and changes the SW control signal SC12 from the high level to the low level (FIG. 14D). This state is maintained for a certain period of time (third period T13e). Then, the control signal generation circuit 8 changes the SW control signal SC13 from the high level to the low level (FIG. 14E), and changes the SW control signals SC12 and SC14 from the low level to the high level (FIG. 14 ( D) and (F)), and maintain the state for a certain period of time (fourth period T14e). The control signal generation circuit 8 generates and outputs SW control signals SC11 to SC14 so as to repeat a series of operations including these four periods T11e to T14e during the touch detection time T1e.

  Next, with reference to FIG. 15 and FIG. 16, the detailed operation of the sensor unit 7 in the periods T11e to T14e will be described.

  FIG. 15 illustrates a timing chart of the operation of the sensor unit 7 in the periods T11e to T14e. 15A shows the voltage waveform of the SW control signal SC11, FIG. 15B shows the voltage waveform of the SW control signal SC12, FIG. 15C shows the voltage waveform of the SW control signal SC13, and FIG. The voltage waveform of SW control signal SC14 is shown, (E) shows the waveform of electrode voltage Vel1 of electrode 21, (F) shows the waveform of electrode voltage Vel2 of electrode 22. Here, for convenience of explanation, it is assumed that the sensor unit 7 and the detection unit 3 are disconnected regardless of the state of the switching element SW14. That is, it is assumed that no accumulated current flows from the electrode 22 of the sensor unit 7 to the capacitive element Cstr of the detection unit 3.

  FIG. 16 shows the state of the sensor unit 7 in the touch detection period T1e, (A) shows the state in the first period T11e, (B) shows the state in the second period T12e, C) shows a state in the third period T13e, and (D) shows a state in the fourth period T14e.

  In the first period T11e, as shown in FIG. 16A, the switching elements SW11 and SW13 are in the on state, and the switching elements SW12 and SW14 are in the off state. As a result, the voltage VDD is applied (initialized) to the electrodes 21 and 22 (FIGS. 15E and 15F).

  In the second period T12e, as shown in FIG. 16B, the switching element SW12 is in the on state, and the switching elements SW11, SW13, and SW14 are in the off state. Thus, 0 V is applied to the electrode 21 (FIG. 15E). At this time, part of the charge of the capacitance Cg2 (charge amount Q12e) transiently flows into the capacitance Cm as a current (FIG. 16B). Thus, as the electrode voltage Vel1 of the electrode 21 decreases to 0V, the electrode voltage Vel2 of the electrode 22 also decreases, but does not become 0V but becomes the voltage ΔV1 (FIG. 15 (F)). In other words, the electrode voltage Vel2 of the electrode 22 is higher than the electrode voltage Vel1 of the electrode 21 by the voltage ΔV1.

  In the third period T13e, as shown in FIG. 16C, the switching element SW13 is in the on state, and the switching elements SW11, SW12, and SW14 are in the off state. Thus, the voltage VDD is applied to the electrode 22 (FIG. 15F). At this time, a part of the charge of the capacitance Cm (charge amount Q13e) transiently flows into the capacitance Cg1 as a current (FIG. 16C). Thereby, as the electrode voltage Vel2 of the electrode 22 rises to the voltage VDD, the electrode voltage Vel1 of the electrode 21 also rises, but does not become the voltage VDD but becomes the voltage VDD−ΔV2 (FIG. 15E). In other words, the electrode voltage Vel2 of the electrode 22 is higher than the electrode voltage Vel1 of the electrode 21 by the voltage ΔV2. This voltage ΔV2 corresponds to the sum of the charge amount Q12e and the charge amount Q13e.

  In the fourth period T14e, as illustrated in FIG. 16D, the switching elements SW12 and SW14 are in the on state, and the switching elements SW11 and SW13 are in the off state. Thus, 0 V is applied to the electrode 21 (FIG. 15E). At this time, a part of the charge of the capacitance Cg2 (charge amount Q14e) transiently flows into the capacitance Cm as a current (FIG. 16D). Thus, as the electrode voltage Vel1 of the electrode 21 decreases to 0V, the electrode voltage Vel2 of the electrode 22 also decreases, but does not become 0V but becomes the voltage ΔV3 (FIG. 15 (F)). In other words, the electrode voltage Vel2 of the electrode 22 is higher than the electrode voltage Vel1 of the electrode 21 by the voltage ΔV3. This voltage ΔV3 corresponds to the sum of the charge amount Q12e, the charge amount Q13e, and the charge amount Q14e.

  As described above, in each period from the second period T12e to the fourth period T14e, the transient current due to the capacitance Cm and the capacitances Cg1 and Cg2 flows, and the voltage difference between the electrode voltage Vel1 and the electrode voltage Vel2 occurs. Will occur. Furthermore, the voltage difference is amplified with the progress of the period, and the electrode voltage Vel2 of the electrode 22 becomes gradually larger than the electrode voltage Vel1 of the electrode 21 (FIGS. 15E and 15F).

  In the above, for convenience of explanation, it is assumed that the sensor unit 7 and the detection unit 3 are disconnected regardless of the state of the switching element SW14, but actually, in the fourth period T14e, the electrode 22 of the sensor unit 7 is used. Is connected to the capacitive element Cstr of the detector 3. As a result, a part of the charges of the electrostatic capacitances Cm and Cg2 flows into the capacitive element Cstr as the transient accumulated current Istr through the switching element SW14 from the electrode 22 where the electrode voltage Vel2 is amplified. Then, the storage voltage Vstr rises by the amount of electric charge that flows as the transient storage current Istr (FIG. 14 (I)).

  Thereafter, a series of operations including the first period T11e to the fourth period T14e is repeated, so that the switching element SW14 is turned on in the fourth period T14e based on the operation principle of the so-called switched capacitor. As a result, charges are accumulated in the capacitive element Cstr, and accordingly, the accumulated voltage Vstr rises (FIG. 14 (I)).

  When the accumulated voltage Vstr (comparator input voltage Vcomp) exceeds the voltage level of the reference voltage Vref, the comparator circuit 30 outputs a high level voltage as the comparison result (detection signal Vdet) (FIG. 14). (K)). That is, the detection signal Vdet is the time (accumulation time tstr) until the charge accumulation amount of the capacitance element Cstr reaches a certain amount (Cstr × Vref) after the accumulation of the charge in the capacitance element Cstr is started. Maintain a low level. The touch determination unit 4 detects the accumulation time tstr based on the detection signal Vdet, and detects the presence or absence of an external proximity object using this.

(Operation of the touch sensor 90 when there is an external proximity object)
Next, an operation example of the touch detection period T1e when there is an external proximity object in the touch detection area of the touch sensor 90 will be described.

  Even when there is an external proximity object, the sensor unit 2 operates as shown in FIGS. 14 and 15 in the touch detection period T1e as in the case where there is no external proximity object. However, the transient currents generated in the second period T12e, the third period T13e, and the fourth period T14e are different depending on the presence or absence of an external proximity object, and as a result, the voltages ΔV1 to ΔV3 are also different.

  As shown in FIG. 2, the capacitances Cm, Cg1, and Cg2 change depending on the presence or absence of an external proximity object in the touch detection area of the touch sensor 10. That is, regarding the capacitance Cm, the value when there is an external proximity object (capacitance Cmb) is smaller than the value when there is no external proximity object (capacitance Cma). Regarding the capacitances Cg1 and Cg2, values when there is an external proximity object (Cp1 + Cf1, Cp2 + Cf2) are larger than values when there is no external proximity object (Cp1, Cp2). Accordingly, the voltages ΔV1 to ΔV3 when there is an external proximity object are larger than when there is no external proximity object. Therefore, in the fourth period T14e, the transient accumulated current Istr flowing from the electrode 22 to the capacitive element Cstr is also larger than when there is no external proximity object.

  FIG. 17 is an example of a timing diagram of the touch sensor 90 according to the present embodiment, and represents an example when there is an external proximity object. 17A shows the voltage waveform of the SW control signal SA, FIG. 17B shows the voltage waveform of the SW control signal SB, FIG. 17C shows the voltage waveform of the SW control signal SC11, and FIG. The voltage waveform of the SW control signal SC12 is shown, (E) shows the voltage waveform of the SW control signal SC13, (F) shows the voltage waveform of the SW control signal SC14, and (G) shows the waveform of the electrode voltage Vel1 of the electrode 21. (H) shows the waveform of the electrode voltage Vel2 of the electrode 22, (I) shows the waveform of the accumulated voltage Vstr, (J) shows the waveform of the comparator input voltage Vcomp, and (K) shows the detection signal Vdet. The waveform is shown.

  In the case where there is an external proximity object, for example, in the fourth period T14e, the transient accumulated current Istr increases, and the accumulated amount of charge in the capacitive element Cstr into which it flows increases. The amount of increase will also increase. In the touch detection period T1e, a series of operations including the first period T11e to the fourth period T14e are repeated, so that the accumulated voltage Vstr increases every fourth period T14e. In some cases, the rate of change of the accumulated voltage Vstr increases. Due to this, when there is an external proximity object, the accumulation time tstr is shortened (FIG. 17K).

  As described above, the accumulation time tstr varies depending on the presence or absence of an external proximity object. Therefore, the determination circuit of the touch determination unit 4 can determine the presence or absence of an external proximity object by comparing the accumulation time tstr with a predetermined reference time tref.

[effect]
As described above, in the present embodiment, both the first electrode and the second electrode are used as drive electrodes, and the switched capacitor operation is repeated a plurality of times between these electrodes. Even when information corresponding to the presence / absence is amplified and the sensor unit is configured by small electrodes, the presence / absence of an external proximity object can be detected with high accuracy. In particular, when a display device with a touch sensor is configured using a sensor portion having small electrodes, the frame portion can be narrowed because the sensor portion can be reduced in size. Other effects are the same as in the case of the first embodiment.

[Modification 2-1]
In the above embodiment, the touch detection period T1e has four periods T11e to T14e and is repeated. However, the present invention is not limited to this, and has n periods (n is a natural number). However, this may be repeated. When n is an even number, the same circuit configuration as that of the touch sensor 90 (FIG. 13) in the present embodiment (n = 4) can be used, and the timing chart thereof is the same as in FIGS. Can be used. Specifically, the timing diagram can be obtained by alternately adding the second period T12e and the third period T13e in FIGS. 14 and 15 as many times as necessary. For example, when n = 6, the touch detection period T1e has six periods (T11e, T12e, T13e, T12e, T13e, and T14e), and this is repeated. On the other hand, when n is an odd number, the circuit configuration is, for example, as shown in FIG.

  FIG. 18 illustrates a circuit configuration example of the touch sensor when n is an odd number. The touch sensor 90F includes a sensor unit 7F and a drive signal generation circuit 8F. Other configurations are the same as those of the present embodiment (FIG. 13). The sensor unit 7F includes electrodes 21 and 22 and switching elements SW21 to SW24. The switching element SW21 is disposed between the ground (GND) and the electrode 21, is on / off controlled by the SW control signal SC21, and applies the ground (GND) to the electrode 21 in a time-sharing manner. The switching element SW22 is arranged between the voltage VDD and the electrode 22, and is subjected to on / off control by the SW control signal SC22, and applies the voltage VDD to the electrode 22 in a time-sharing manner. The switching element SW23 is arranged between the ground (GND) and the electrode 22, is on / off controlled by the SW control signal SC23, and applies the ground (GND) to the electrode 22 in a time-sharing manner. The switching element SW24 is disposed between the electrode 22 and the capacitive element Cstr of the detection unit 7, and ON / OFF control is performed by the SW control signal SC24. Based on the timing control circuit 6, the signal generation circuit 8F generates the SW control signals SA, SB, SC21 to SC24, supplies the SW control signals SA and SB to the detection unit 3, and supplies the SW control signals SC21 to SC24. It supplies to the sensor part 7F.

  FIG. 19 shows a timing chart of the operation of the sensor unit 7F when n = 5. In this case, the five periods include T11f, T12f, T13f, T14f, and T15f. The voltage difference Vel2-Vel1 between the electrode voltage Vel1 of the electrode 21 and the electrode voltage Vel2 of the electrode 22 is the voltage ΔV1 in the second period T12f, the voltage ΔV2 in the third period T13f, and the voltage ΔV3 in the fourth period T14f. Thus, the voltage ΔV4 in the fifth period T15f amplifies the electrode voltage Vel2 of the electrode 22, and the transient accumulated current Istr flows from the electrode 22 to the capacitive element Cstr. Accumulated. Then, by repeating a series of operations including the first period T11f to the fifth period T15f, the switching element SW24 is turned on in the fifth period T15f based on the operation principle of the so-called switched capacitor. Every time the charge is accumulated in the capacitive element Cstr, the accumulated voltage Vstr rises accordingly.

  As described above, the number of times the switched capacitor operation is repeated between the first electrode and the second electrode can be set to an arbitrary number. Therefore, by increasing the number of repetitions, information corresponding to the presence or absence of an external proximity object is amplified, and the presence or absence of an external proximity object can be detected with higher accuracy.

[Modification 2-2]
As in the first embodiment, the touch sensor according to the present embodiment may measure the rate of change of the accumulated voltage Vstr as the voltage value of the accumulated voltage Vstr at a certain timing. At that time, as shown in FIGS. 10 and 12, the detection unit may be configured using an ADC circuit.

<3. Specific application examples>
Next, specific application examples of the touch sensor and the display device with the touch sensor described in the above embodiment and the modified examples will be described with reference to FIGS.

(Application 1)
20A and 20B illustrate an example of the display operation and touch sensor operation of the portable information terminal 110. FIG. As shown in FIG. 20A, the display unit 17A with the touch sensor is arranged in the frame area of the main screen 100. For example, the display unit with the touch sensor is displayed by the user according to the content displayed on the main screen 100. Information can be input using 17A. The display unit 17A with a touch sensor includes the sensor unit 2 and the sensor display unit 14 as in the case shown in FIG. The display unit 17A with a touch sensor is preferably formed on the same array substrate as the main screen 100 (effective display area) from the viewpoint of space saving. In particular, the sensor display unit 14 is the same as the main screen 100. It is desirable to have a display element of the structure. Specifically, when the main screen 100 uses a liquid crystal element, it is desirable that the sensor display unit 14 performs display using the liquid crystal element.

  The portable information terminal 110 has a function of inputting information by touching the corresponding display unit 17A with a touch sensor in accordance with the content displayed on the main screen 100. For example, in FIG. 20A, the user can select one of four functions by touching the display unit 17A with a touch sensor. In FIG. 20B, for example, when the portable information terminal 110 has a function of outputting sound, the user slides and moves his / her finger across the plurality of display units 17A with touch sensors. The volume can be adjusted. Thus, in the portable information terminal 110, by changing the content displayed on the main screen 100, various information according to the display content can be input using the display unit 17A with a touch sensor.

(Application example 2)
FIG. 21 illustrates an example of the display operation and the touch sensor operation of the portable information terminal 120, (A) shows a plan view of the portable information terminal 120, and (B) shows a configuration example of the display unit 17B with a touch sensor. Indicates. As shown in FIG. 21A, the display unit with a touch sensor 17B is arranged at a location adjacent to the main screen 100 and the sub screen 101. For example, the user can display the display unit 17B on the main screen 100 or the sub screen 101. In accordance with the contents, information can be input using the display unit 17B with a touch sensor, or display on the main screen 100 and the sub screen 101 can be confirmed while inputting information using the display unit 17B with a touch sensor. ing. The display unit 17B with the touch sensor includes the sensor unit 2 and the display element 102 as illustrated in FIG. The display element 102 is one display element that constitutes the sensor display unit 14 of FIG. These are arranged in a matrix in the display unit 17B with a touch sensor, and ensure a certain degree of freedom of display and also have a function of detecting a touch position. The display unit 17B with a touch sensor is desirably formed on at least the same substrate as the sub screen 101 (effective display area) from the viewpoint of space saving, and has a display element having the same structure as the sub screen 101. Is desirable. Further, the sensor display unit 14 may be formed not only on the sub screen 101 but also on the same substrate as the main screen 100 (effective display area), and the sensor display unit 14, the main screen 100, and the sub screen 101 are mutually connected. It is desirable to have display elements having the same structure.

  In this example, the portable information terminal 120 has a function of inputting information using buttons displayed on the touch sensor display unit 17B in accordance with the contents displayed on the main screen 100 or the sub screen 101. Similarly to the portable information terminal 101, by changing the content displayed on the main screen 100 or the sub screen 101, various information according to the display content can be input. Furthermore, by changing the display content of the touch sensor display unit 17B itself, for example, the user can more intuitively understand the operation method. In addition, by using the touch position detection function, for example, it is possible to display a plurality of buttons on the touch sensor display unit 17B and to input a plurality of information.

(Application 3)
22A and 22B show an example of the display operation and touch sensor operation of the portable information terminal 130. FIG. 22A is a plan view of the portable information terminal 130, and FIG. 22B is a configuration example of the display unit 17C with a touch sensor. Indicates. As shown in FIG. 22A, the display unit with a touch sensor 17C is arranged at a location adjacent to the main screen 100 and the sub screen 101. The configuration of the display unit 17C with a touch sensor is the same as that of the display unit 17B with a touch sensor (FIG. 21B), as shown in FIG. It also has a function of position detection.

  In this example, the portable information terminal 130 has a function of inputting information according to the contents displayed on the main screen 100 or the sub-screen 101 by using a selection switch indicating four directions displayed on the touch sensor display unit 17C. This makes it possible to input more information without depending on the number of selection switches.

(Application 4)
23A and 23B show an example of the display operation and touch sensor operation of the portable information terminal 140. FIG. 23A is a plan view of the portable information terminal 140, and FIG. 23B is a configuration example of the display unit 17D with a touch sensor. Indicates. The display unit 17D with a touch sensor is arranged at a location adjacent to the main screen 100 and the sub screen 101 as shown in FIG. Further, the mobile information terminal 140 is also provided with a display unit with a touch sensor (in this example, display unit 17C with a touch sensor) having an information input function different from the display unit with touch sensor 17D. As shown in FIG. 23B, the configuration of the display unit 17D with a touch sensor is the same as that of the display units 17B (FIG. 21B) and 17C (FIG. 22B) with a touch sensor. While ensuring a certain degree of freedom, it also has a function of detecting the touch position.

  The portable information terminal 140 has a function of inputting information using the touch sensor display units 17C and 17D in accordance with the contents displayed on the main screen 100 or the sub screen 101. For example, in FIG. 23B, when the portable information terminal 140 has a function of displaying a photograph on the main screen 100, for example, the user displays a ring-shaped graphic displayed on the display unit 17D with a touch sensor. Can be instructed to enlarge or reduce a part of the photograph as a so-called rotary switch. Moreover, in the portable information terminal 140, by providing a plurality of touch sensor display units 17C and 17D, various information can be input in parallel.

  Further, in any portable information terminal, the function of the button (FIG. 21B) and the selection switch (FIG. 22 (FIG. 22B)) are not fixed depending on the operation content in the portable information terminal without fixing the function of the display unit with the touch sensor. By switching the function of B)), the degree of freedom of information input becomes higher. Thereby, especially in a small-sized or multifunctional portable information terminal, the user interface is greatly improved.

<4. Application example to electronic equipment>
Next, with reference to FIGS. 24 to 28, application examples of the display device with a touch sensor described in the above embodiment and the modified examples to electronic devices will be described. The display device with a touch sensor in the above-described embodiments can be applied to electronic devices in various fields such as a television device, a digital camera, a notebook personal computer, a mobile terminal device such as a mobile phone, or a video camera. . In other words, the display device with a touch sensor according to the above-described embodiment or the like can be applied to electronic devices in various fields that display an externally input video signal or an internally generated video signal as an image or video. is there.

(Application example 1)
FIG. 24 illustrates an appearance of a television device to which the display device with a touch sensor according to the above-described embodiment and the like is applied. The television apparatus has, for example, a video display screen unit 510 including a front panel 511 and a filter glass 512, and the video display screen unit 510 is configured by the display device with a touch sensor according to the above-described embodiment and the like. Has been.

(Application example 2)
FIG. 25 illustrates an appearance of a digital camera to which the display device with a touch sensor according to the above-described embodiment or the like is applied. The digital camera includes, for example, a flash light emitting unit 521, a display unit 522, a menu switch 523, and a shutter button 524. The display unit 522 is provided by the display device with a touch sensor according to the above-described embodiment and the like. It is configured.

(Application example 3)
FIG. 26 illustrates an appearance of a notebook personal computer to which the display device with a touch sensor according to the above-described embodiment or the like is applied. The notebook personal computer includes, for example, a main body 531, a keyboard 532 for inputting characters and the like, and a display unit 533 for displaying an image. The display unit 533 is a touch according to the above-described embodiment and the like. It is comprised by the display apparatus with a sensor.

(Application example 4)
FIG. 27 illustrates an appearance of a video camera to which the display device with a touch sensor according to the above-described embodiment or the like is applied. This video camera has, for example, a main body 541, a subject shooting lens 542 provided on the front side surface of the main body 541, a start / stop switch 543 at the time of shooting, and a display 544. And the display part 544 is comprised by the display apparatus with a touch sensor which concerns on the said embodiment etc.

(Application example 5)
FIG. 28 illustrates an appearance of a mobile phone to which the display device with a touch sensor according to the above-described embodiment and the like is applied. For example, the mobile phone is obtained by connecting an upper housing 710 and a lower housing 720 with a connecting portion (hinge portion) 730, and includes a display 740, a sub-display 750, a picture light 760, and a camera 770. Yes. The display 740 or the sub-display 750 is configured by a display device with a touch sensor according to the above-described embodiment or the like.

  As described above, the present invention has been described with reference to some embodiments and modifications, and specific application examples and application examples to electronic devices. However, the present invention is not limited to these embodiments and the like. However, various modifications are possible.

  In the above-described embodiment and the like, liquid crystal elements are used as the display elements of the effective display area 13 and the sensor display unit 14, but the present invention is not limited to this, and instead, for example, both organic EL ( An EL element such as an Electro Luminescence element may be used. Further, display elements having different structures may be used for the effective display region 13 and the sensor display unit 14.

  In the above-described embodiment and the like, the sensor display unit 14 performs display in the same manner as the effective display area 13, but is not limited to this. For example, the display content of the sensor display unit 14 is fixed. Also good. In this case, for example, the sensor display unit 14 emits light from the backlight without passing through the liquid crystal, and displays the display through a symbol or the like indicating a function printed in advance on a cover member disposed on the surface of the sensor display unit 14. You may do it. In addition, when space saving is not important, for example, the sensor display unit 14 is newly provided with a light emitting diode, emits light from the light emitting diode, and similarly displays through a preprinted symbol or the like. There may be.

  In the above embodiment and the like, the sensor display unit 14 is provided, but this may not be provided. Even in this case, it is possible to reduce the size by forming the sensor unit 2 and the detection unit 3 on the same array substrate 11.

DESCRIPTION OF SYMBOLS 1 ... Display apparatus with a touch sensor, 2, 2B, 7, 7F ... Sensor part, 3, 3B, 3C, 3D ... Detection part, 4, 4B, 4C ... Touch determination part, 5, 5C ... Control signal generation part, 6 , 6C ... Timing control circuit, 8, 8F, 50, 50C ... Control signal generation circuit, 10, 10B, 10C, 10D, 90, 90F ... Touch sensor, 11 ... Array substrate, 12 ... Color filter substrate, 13 ... Effective display Area, 14 ... Sensor display section, 15 ... COG, 16 ... Terminal section, 17, 17A, 17B, 17C, 17D ... Display section with touch sensor, 21, 22 ... Electrode, 30 ... Comparator circuit, 31, 32, 51 ... Inverter circuit, 33 ... S / H circuit, 34 ... ADC circuit, 35 ... latch circuit, 41,41B ... time measuring circuit, 42,42C ... determination circuit, 43 ... memory, 100 ... main screen, 10 ... sub-screen, 102A, 102B ... display element, 110, 120, 130, 140 ... portable information terminal, Cdet ... detection code, Ccomp, Cstr ... capacitive element, Cf1, Cf2, Cg, Cm, Cma, Cmb, Cp1, Cp2 ... Capacitance, GND ... Ground, Istr ... Transient current, P1 ... Point, Q12e, Q13e, Q14e ... Charge amount, SA, SB, SC, SCB, SC11-SC14, SC21-SC24 ... SW control signal, SD ... Read Control signals, SW1 to SW8, SW11 to SW14, SW21 to SW24, switching elements, T0, self-offset correction period, T0c, preparation period, T1, T1c, T1e, touch detection period, T11, T12, T11e, T12e, T13e, T14e ... period, T2 ... end period, Tstr ... accumulation time, Vcomp ... comparator input voltage, VDD ... power supply, Vdet ... detection signal , Vel1, Vel2 ... electrode voltage, Vi ... input voltage, Vo ... output voltage, Vout ... touch determination output, Vref ... reference voltage, Vstr ... storage voltage, Vthi, Vthc ... threshold, W1-W3 ... characteristic, [Delta] Vcomp ... Potential difference, ΔV1 to ΔV4 ... Voltage

Claims (14)

A first electrode and a second electrode arranged so that an interelectrode capacitance is formed between them;
A capacitive element;
Between the one that drives the first electrode as a drive electrode, said with the second electrode of Use as a detection electrode, the first driving operation of the electrodes in synchronization with the second electrode the capacitive element A first operation of initializing voltage levels of both the first electrode and the second electrode and controlling the connection state between the second electrode and the capacitive element A drive control unit that applies a drive voltage to the first electrode and connects the second electrode and the capacitive element ;
A touch sensor comprising: a detection unit that detects an external proximity object based on how the voltage of the capacitive element changes. The drive control unit performs control to repeat the first operation and the second operation until the voltage of the capacitive element reaches a predetermined threshold value,
The detection unit detects the external proximity object based on a time until the voltage of the capacitive element reaches the threshold value.
The touch sensor according to claim 1. The drive control unit performs control to repeat the first operation and the second operation a predetermined number of times,
The detection unit detects the external proximity object based on a voltage level of the capacitive element at the time when the predetermined number of repetitions of the first operation and the second operation are completed.
The touch sensor according to claim 1. A first electrode and a second electrode arranged so that an interelectrode capacitance is formed between them;
A capacitive element;
Both the first electrode and the second electrode are driven as drive electrodes, and the second electrode is also used as a detection electrode, and the second electrode is synchronized with the drive operation of the first electrode. A drive control unit for controlling a connection state between the electrode and the capacitive element;
A detection unit for detecting an external proximity object based on a change in voltage of the capacitive element;
Touch sensor equipped with. The drive control unit
An initialization operation for initializing voltage levels of both the first electrode and the second electrode, and disconnecting the second electrode from the capacitor;
Subsequent to the initialization operation, a first drive voltage is applied to either the first electrode or the second electrode while the second electrode and the capacitor are not connected. And an operation of alternately applying a second drive voltage to the other of the first electrode and the second electrode, and the first drive voltage or the second drive is applied to the first electrode. Control is performed so as to perform a driving operation for connecting the second electrode and the capacitive element in the final operation of applying a voltage.
The touch sensor according to claim 4. The drive control unit
A first operation as the initialization operation;
A second operation of applying the first drive voltage to the first electrode while leaving the second electrode and the capacitive element in a disconnected state;
A third operation of applying the second drive voltage to the second electrode while leaving the second electrode and the capacitive element in a disconnected state;
A fourth operation of applying the first driving voltage to the first electrode and connecting between the second electrode and the capacitive element;
Repeat in this order
The touch sensor according to claim 5. The detector is
A first switching element disposed between the input terminal and the reference voltage terminal and controlled to be turned on and off;
Another capacitive element in which one of the two terminals is connected to the input terminal;
An inverting circuit having an input connected to the other terminal of the other capacitive element and an output connected to the output terminal;
A second switching element disposed between the input and output of the inverting circuit and controlled to be turned on and off;
A comparator circuit having
The comparator circuit changes both the first switching element and the second switching element to an off state and then changes to an off state, and refers to the input voltage applied to the input terminal in the off state. Compare with the reference voltage applied to the voltage terminal and output the result from the output terminal
The touch sensor as described in any one of Claims 1-6. The initialization of the first electrode and the second electrode arranged so that the interelectrode capacitance is formed between them and the application of the drive voltage for touch detection to the first electrode are alternately performed. At the same time, a series of operations of connecting a capacitive element to the second electrode in synchronization with the application of the driving voltage to the first electrode is repeated one or more times, whereby the first electrode and the second electrode Each of the electrodes and the ground capacitance formed between the ground, the capacitance between the electrodes, and the capacitance element to move the electric charge to each other to change the voltage of the capacitance element,
The external proximity object is detected by utilizing the fact that the voltage change speed of the capacitive element varies depending on the presence or absence of the external proximity object.
Touch sensor drive method. After initializing the first electrode and the second electrode arranged so that an interelectrode capacitance is formed between each other, the first electrode is set to one of the first electrode and the second electrode. The last operation of applying the first drive voltage or the second drive voltage to the first electrode by alternately performing the operation of applying the second drive voltage and the operation of applying the second drive voltage to the other Is formed between each of the first electrode and the second electrode and the ground by repeating a series of operations of connecting the second electrode and the capacitive element at least once. The voltage of the capacitive element is changed by moving electric charges between the grounded capacitance, the interelectrode capacitance, and the capacitive element,
The external proximity object is detected by utilizing the fact that the voltage change speed of the capacitive element varies depending on the presence or absence of the external proximity object.
Touch sensor drive method. An image display unit that includes a plurality of display elements and that displays an image based on an image signal and a touch sensor unit that is located in a frame area outside the effective display area of the image display unit is integrally formed. Prepared,
The touch sensor unit is
A first electrode and a second electrode arranged so that an interelectrode capacitance is formed between them;
A capacitive element;
While driving the first electrode as a drive electrode, the second electrode is used as a detection electrode, and between the second electrode and the capacitive element in synchronization with the drive operation of the first electrode. A first operation of initializing voltage levels of both the first electrode and the second electrode and controlling the connection state between the second electrode and the capacitive element A drive control unit that applies a drive voltage to the first electrode and connects the second electrode and the capacitive element;
A detection unit for detecting an external proximity object based on a change in voltage of the capacitive element;
Have
Display device with touch sensor. An image display unit that includes a plurality of display elements and that displays an image based on an image signal and a touch sensor unit that is located in a frame area outside the effective display area of the image display unit is integrally formed. Prepared,
The touch sensor unit is
A first electrode and a second electrode arranged so that an interelectrode capacitance is formed between them;
A capacitive element;
Both the first electrode and the second electrode are driven as drive electrodes, and the second electrode is also used as a detection electrode, and the second electrode is synchronized with the drive operation of the first electrode. A drive control unit for controlling a connection state between the electrode and the capacitive element;
A detection unit for detecting an external proximity object based on a change in voltage of the capacitive element;
Have
Display device with touch sensor. The display panel has another display unit including a display element having the same structure as the display element of the image display unit in the frame area.
The display device with a touch sensor according to claim 10 or 11. A touch sensor for detecting an external proximity object;
A processing unit that performs a predetermined process based on information input through the touch sensor;
With
The touch sensor is
A first electrode and a second electrode arranged so that an interelectrode capacitance is formed between them;
A capacitive element;
While driving the first electrode as a drive electrode, the second electrode is used as a detection electrode, and between the second electrode and the capacitive element in synchronization with the drive operation of the first electrode. A first operation of initializing voltage levels of both the first electrode and the second electrode and controlling the connection state between the second electrode and the capacitive element A drive control unit that applies a drive voltage to the first electrode and connects the second electrode and the capacitive element;
A detection unit for detecting the external proximity object based on a change in voltage of the capacitive element;
Have
Electronics. A touch sensor for detecting an external proximity object;
A processing unit that performs a predetermined process based on information input through the touch sensor;
With
The touch sensor is
A first electrode and a second electrode arranged so that an interelectrode capacitance is formed between them;
A capacitive element;
Both the first electrode and the second electrode are driven as drive electrodes, and the second electrode is also used as a detection electrode, and the second electrode is synchronized with the drive operation of the first electrode. A drive control unit for controlling a connection state between the electrode and the capacitive element;
A detection unit for detecting the external proximity object based on a change in voltage of the capacitive element;
Have
Electronics.

Images