JP2012221485A - Display panel with touch detection function, driving method for the same, driving circuit and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a display panel with a touch detection function capable of reducing influence on a display action.SOLUTION: A display panel with a touch detection function comprises: one or more display elements; one or more drive electrodes; one or more touch detection electrodes; and a drive part that applies a DC driving signal VcomDC or an AC driving signal VcomAC selectively to the drive electrodes. In the display panel with a touch detection function, the display elements are driven for display, a driving signal is applied to the drive electrodes, and a signal corresponding to the driving signal is output from the touch detection electrodes. At that time, one of the DC driving signal and the AC driving signal is applied selectively to the drive electrodes.

Description

  The present disclosure relates to a display panel with a touch detection function having a function of detecting a touch by an external proximity object, a driving method thereof, a drive circuit, and an electronic apparatus including such a display panel with a touch detection function.

  In recent years, a touch detection device called a touch panel is mounted on a display device such as a liquid crystal display device, or the touch panel and the display device are integrated to display various button images on the display device. A display panel that can input information as a substitute for a formula button has attracted attention. A display panel having such a touch panel does not require an input device such as a keyboard, a mouse, or a keypad. Therefore, the display panel tends to be used not only for computers but also for portable information terminals such as mobile phones.

  There are several types of touch panel systems such as an optical type and a resistance type, but a capacitive type touch panel having a relatively simple structure and realizing low power consumption is expected. For example, in Patent Document 1, a display common electrode originally provided in a display device is used as one of a pair of touch sensor electrodes, and the other electrode (touch detection electrode) is used as the common electrode. A so-called in-cell type display panel with a touch detection function arranged so as to intersect has been proposed. Some so-called on-cell type display panels with a touch detection function in which a touch panel is formed on the display surface of a display device have been proposed.

JP 2009-244958 A

  By the way, in the display panel with a touch detection function, since the display function and the touch detection function are integrated, for example, an operation for touch detection may affect the display operation. However, Patent Document 1 does not describe this influence and countermeasures at all.

  The present disclosure has been made in view of such problems, and an object thereof is to provide a display panel with a touch detection function capable of reducing the influence on display operation, a driving method thereof, a driving circuit, and an electronic device. It is in.

  The display panel with a touch detection function of the present disclosure includes one or more display elements, one or more drive electrodes, one or more touch detection electrodes, and a drive unit. The drive unit selectively applies a DC drive signal or an AC drive signal to the drive electrodes.

  The method for driving a display panel with a touch detection function according to the present disclosure is a method for driving one or a plurality of display elements and selectively applying a DC drive signal or an AC drive signal to one or a plurality of drive electrodes. is there.

  The drive circuit of the present disclosure includes a display drive unit and a touch detection drive unit. The display driving unit drives one or a plurality of display elements. The touch detection drive unit selectively applies a DC drive signal or an AC drive signal to one or a plurality of drive electrodes.

  An electronic device according to the present disclosure includes the above-described display panel with a touch detection function, and corresponds to a mobile terminal device such as a television device, a digital camera, a personal computer, a video camera, or a mobile phone.

  In the display panel with a touch detection function of the present disclosure, a driving method thereof, a driving circuit, and an electronic device, the display element is driven to display, a driving signal is applied to the driving electrode, and the driving signal is output from the touch detecting electrode. A signal corresponding to is output. At that time, one of a DC drive signal and an AC drive signal is selectively applied to the drive electrode.

  According to the display panel with a touch detection function and the driving method, the driving circuit, and the electronic apparatus according to the present disclosure, the direct current driving signal or the alternating current driving signal is selectively applied to the driving electrode. Can be reduced.

It is a figure for demonstrating the basic principle of the touch detection system in the display panel with a touch detection function of this indication, and is a figure showing the state which the finger | toe does not touch or adjoin. It is a figure for demonstrating the basic principle of the touch detection system in the display panel with a touch detection function of this indication, and is a figure showing the state which the finger | toe contacted or adjoined. It is a figure for demonstrating the basic principle of the touch detection system in the display panel with a touch detection function of this indication, and is a figure showing an example of the waveform of a drive signal and a touch detection signal. It is a block diagram showing the example of 1 composition of the display panel with a touch detection function concerning an embodiment of this indication. FIG. 5 is a block diagram illustrating a configuration example of a selection switch unit illustrated in FIG. 4. FIG. 5 is a cross-sectional view illustrating a schematic cross-sectional structure of the display device with a touch detection function illustrated in FIG. 4. FIG. 5 is a circuit diagram illustrating a pixel array in the display device with a touch detection function illustrated in FIG. 4. FIG. 5 is a perspective view illustrating a configuration example of drive electrodes and touch detection electrodes in the display device with a touch detection function illustrated in FIG. 4. FIG. 5 is a schematic diagram illustrating an operation example of touch detection scanning in the display panel with a touch detection function illustrated in FIG. 4. FIG. 5 is a schematic diagram illustrating an operation example of display scanning and touch detection scanning in the display panel with a touch detection function illustrated in FIG. 4. FIG. 5 is a block diagram illustrating a configuration example of a drive signal generation unit illustrated in FIG. 4. It is a block diagram showing the example of 1 structure of the drive electrode driver which concerns on 1st Embodiment. FIG. 6 is a timing waveform diagram illustrating an operation example of the display panel with a touch detection function according to the first embodiment. It is a timing waveform diagram showing an example of a touch detection operation in the display panel with a touch detection function according to the first embodiment. It is a block diagram showing the example of 1 structure of the drive signal generation part which concerns on a comparative example. It is a block diagram showing the example of 1 structure of the drive electrode driver which concerns on a comparative example. It is a timing waveform diagram showing an operation example of a display panel with a touch detection function according to a comparative example. It is a block diagram showing the example of 1 structure of the drive signal generation part which concerns on the modification of embodiment. It is a block diagram showing the example of 1 structure of the drive electrode driver which concerns on the other modification of embodiment. It is a schematic diagram showing the operation example of the touch detection scanning which concerns on the other modification of embodiment. FIG. 16 is a timing waveform chart illustrating an operation example of a display panel with a touch detection function according to another modification of the embodiment. It is a block diagram showing the example of 1 structure of the drive electrode driver which concerns on 2nd Embodiment. FIG. 10 is a timing waveform diagram illustrating an operation example of a display panel with a touch detection function according to a second embodiment. It is a timing waveform diagram showing an example of the touch detection operation in the display panel with a touch detection function according to the second embodiment. It is a perspective view showing the appearance composition of application example 1 among display panels with a touch detection function 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 an application example 5. It is sectional drawing showing the schematic sectional structure of the display device with a touch detection function which concerns on a modification.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The description will be given in the following order.
1. 1. Basic principle of capacitive touch detection First Embodiment 3. FIG. Second embodiment 4. Application examples

<1. Basic Principle of Capacitive Touch Detection>
First, the basic principle of touch detection in the display panel with a touch detection function of the present disclosure will be described with reference to FIGS. This touch detection method is embodied as a capacitive touch sensor. For example, as shown in FIG. 1A, a pair of electrodes (drives) arranged opposite to each other with a dielectric D interposed therebetween. A capacitive element is configured using the electrode E1 and the touch detection electrode E2). This structure is expressed as an equivalent circuit shown in FIG. The drive element E1, the touch detection electrode E2, and the dielectric D constitute a capacitive element C1. One end of the capacitive element C1 is connected to an AC signal source (drive signal source) S, and the other end P is grounded via a resistor R and also connected to a voltage detector (touch detection circuit) DET. When an AC rectangular wave Sg (FIG. 3B) having a predetermined frequency (for example, about several kHz to several tens of kHz) is applied from the AC signal source S to the drive electrode E1 (one end of the capacitive element C1), the touch detection electrode E2 ( An output waveform (touch detection signal Vdet) as shown in FIG. 3A appears at the other end P) of the capacitive element C1. The AC rectangular wave Sg corresponds to an AC drive signal VcomAC described later.

  In a state where the finger is not in contact (or close proximity), as shown in FIG. 1, a current I0 corresponding to the capacitance value of the capacitive element C1 flows along with charging / discharging of the capacitive element C1. The potential waveform at the other end P of the capacitive element C1 at this time is, for example, a waveform V0 in FIG. 3A, which is detected by the voltage detector DET.

  On the other hand, when the finger is in contact (or close proximity), the capacitive element C2 formed by the finger is added in series to the capacitive element C1, as shown in FIG. In this state, currents I1 and I2 flow in accordance with charging and discharging of the capacitive elements C1 and C2, respectively. The potential waveform at the other end P of the capacitive element C1 at this time is, for example, a waveform V1 in FIG. 3A, and this is detected by the voltage detector DET. At this time, the potential at the point P is a divided potential determined by the values of the currents I1 and I2 flowing through the capacitive elements C1 and C2. For this reason, the waveform V1 is smaller than the waveform V0 in the non-contact state. The voltage detector DET compares the detected voltage with a predetermined threshold voltage Vth, and determines that it is in a non-contact state if it is equal to or higher than this threshold voltage, and determines that it is in a contact state if it is less than the threshold voltage. To do. In this way, touch detection is possible.

<2. First Embodiment>
[Configuration example]
(Overall configuration example)
FIG. 4 illustrates a configuration example of the display panel 1 with a touch detection function according to the first embodiment. This display panel with a touch detection function uses a liquid crystal display element as a display element, and is a so-called in-cell type in which a liquid crystal display device constituted by the liquid crystal display element and a capacitive touch detection device are integrated. It is a display panel.

  The display panel with a touch detection function 1 includes a control unit 11, a gate driver 12, a source driver 13, a selection switch unit 14, a drive signal generation unit 15, a drive electrode driver 16, and a display device with a touch detection function. 10 and a touch detection unit 40.

  The control unit 11 supplies control signals to the gate driver 12, the source driver 13, the drive signal generation unit 15, the drive electrode driver 16, and the touch detection unit 40 based on the video signal Vdisp supplied from the outside. These are circuits for controlling these to operate in synchronization with each other.

  The gate driver 12 has a function of sequentially selecting one horizontal line as a display driving target of the display device 10 with a touch detection function based on a control signal supplied from the control unit 11. Specifically, the gate driver 12 generates a scanning signal Vscan based on the control signal supplied from the control unit 11, and the scanning signal Vscan is transmitted to the TFT element Tr of the pixel Pix via the scanning signal line GCL. By applying to the gate, one row (one horizontal line) of the pixels Pix formed in a matrix on the liquid crystal display device 20 of the display device with a touch detection function 10 is sequentially selected as a display drive target.

  The source driver 13 generates and outputs a pixel signal Vsig based on the video signal and the source driver control signal supplied from the control unit 11. Specifically, as will be described later, the source driver 13 uses a plurality of (three in this example) subpixels SPix of the liquid crystal display device 20 of the display device 10 with a touch detection function from a video signal for one horizontal line. A pixel signal Vsig obtained by time-division multiplexing the pixel signal Vpix is generated and supplied to the selection switch unit 14. The source driver 13 generates a switch control signal Vsel (VselR, VselG, VselB) necessary for separating the pixel signal Vpix multiplexed on the pixel signal Vsig, and supplies the switch control signal Vsel to the selection switch unit 14 together with the pixel signal Vsig. It also has a function to do. This multiplexing is performed in order to reduce the number of wires between the source driver 13 and the selection switch unit 14.

  The selection switch unit 14 separates the pixel signal Vpix time-division multiplexed on the pixel signal Vsig based on the pixel signal Vsig and the switch control signal Vsel supplied from the source driver 13, and the liquid crystal of the display device 10 with a touch detection function. This is supplied to the display device 20.

  FIG. 5 illustrates a configuration example of the selection switch unit 14. The selection switch unit 14 includes a plurality of switch groups 17. In this example, each switch group 17 has three switches SWR, SWG, and SWB, one ends of which are connected to each other and the pixel signal Vsig is supplied from the source driver 13, and the other end is a display with a touch detection function. The pixel 10 is connected to three subpixels SPix (R, G, B) related to the pixel Pix via the pixel signal line SGL of the liquid crystal display device 20 of the device 10. The three switches SWR, SWG, SWB are controlled to be turned on / off by a switch control signal Vsel (VselR, VselG, VselB) supplied from the source driver 13, respectively. With this configuration, the selection switch unit 14 switches the three switches SWR, SWG, SWB sequentially in a time division manner according to the switch control signal Vsel to turn them on so that the pixel signal Vsig is multiplexed. It functions to separate the signals Vpix (VpixR, VpixG, VpixB). The selection switch unit 14 supplies these pixel signals Vpix to the three subpixels SPix.

  The drive signal generation unit 15 generates the drive signal Vcom based on the control signal supplied from the control unit 11. Specifically, the drive signal generation unit 15 generates a DC drive signal VcomDC as described later, and generates an AC drive signal VcomAC based on a Vcom control signal EXVCOM (described later) supplied from the control unit 11. , Supplied to the drive electrode driver 16. The DC drive signal VcomDC is a DC signal having a voltage of 0 V in this example. The AC drive signal VcomAC is a signal having a pulse waveform in which the low level voltage is 0 V and the high level voltage is VH.

  The drive electrode driver 16 is a circuit that supplies a drive signal Vcom to drive electrodes COML (described later) of the display device with a touch detection function 10 based on a control signal supplied from the control unit 11. Specifically, in the touch detection operation, the drive electrode driver 16 applies the AC drive signal VcomAC to the drive electrode COML related to the touch detection operation. At that time, the drive electrode driver 16 drives the drive electrode COML for each block (drive electrode block B described later) including a predetermined number of drive electrodes COML. Further, the drive electrode driver 16 applies a DC drive signal VcomDC to the drive electrodes COML other than the drive electrode COML related to the touch detection operation.

  The display device 10 with a touch detection function is a display device with a built-in touch detection function. The display device with a touch detection function 10 includes a liquid crystal display device 20 and a touch detection device 30. As will be described later, the liquid crystal display device 20 is a device that performs scanning by sequentially scanning one horizontal line at a time in accordance with a scanning signal Vscan supplied from the gate driver 12. The touch detection device 30 operates based on the basic principle of the capacitive touch detection described above, and outputs a touch detection signal Vdet. As will be described later, the touch detection device 30 performs touch detection by sequentially scanning in accordance with an AC drive signal VcomAC supplied from the drive electrode driver 16.

  The touch detection unit 40 detects the touch of the touch detection device 30 based on the touch detection control signal supplied from the control unit 11 and the touch detection signal Vdet supplied from the touch detection device 30 of the display device 10 with a touch detection function. This is a circuit that detects presence / absence and obtains the coordinates in the touch detection area when there is a touch. The touch detection unit 40 includes an LPF (Low Pass Filter) unit 42, an A / D conversion unit 43, a signal processing unit 44, a coordinate extraction unit 45, and a detection timing control unit 46. The LPF unit 42 is a low-pass analog filter that removes a high frequency component (noise component) included in the touch detection signal Vdet supplied from the touch detection device 30, extracts the touch component, and outputs it. A resistor R for applying a DC potential (for example, 0 V) is connected between each of the input terminals of the LPF unit 42 and the ground. In place of the resistor R, for example, a switch may be provided, and a DC potential (0 V) may be applied by turning on the switch at a predetermined time. The A / D conversion unit 43 is a circuit that samples each analog signal output from the LPF unit 42 and converts it into a digital signal at a timing synchronized with the AC drive signal VcomAC. The signal processing unit 44 is a logic circuit that detects the presence or absence of a touch on the touch detection device 30 based on the output signal of the A / D conversion unit 43. The coordinate extraction unit 45 is a logic circuit that calculates touch panel coordinates when touch detection is performed in the signal processing unit 44. The detection timing control unit 46 controls these circuits to operate in synchronization.

(Display device with touch detection function 10)
Next, a configuration example of the display device 10 with a touch detection function will be described in detail.

  FIG. 6 illustrates an example of a cross-sectional structure of a main part of the display device 10 with a touch detection function. The display device with a touch detection function 10 includes a pixel substrate 2, a counter substrate 3 disposed opposite to the pixel substrate 2, and a liquid crystal layer 6 interposed between the pixel substrate 2 and the counter substrate 3. It has.

  The pixel substrate 2 includes a TFT substrate 21 as a circuit substrate, a drive electrode COML, and a pixel electrode 22. The TFT substrate 21 functions as a circuit substrate on which various electrodes, wirings, thin film transistors (TFTs), and the like are formed. The TFT substrate 21 is made of, for example, glass. A drive electrode COML is formed on the TFT substrate 21. The drive electrode COML is an electrode for supplying a common voltage to a plurality of pixels Pix (described later). The drive electrode COML functions as a common drive electrode for a liquid crystal display operation and also functions as a drive electrode for a touch detection operation. An insulating layer 23 is formed on the drive electrode COML, and a pixel electrode 22 is formed thereon. The pixel electrode 22 is an electrode for supplying a pixel signal for display and has translucency. The drive electrode COML and the pixel electrode 22 are made of, for example, ITO (Indium Tin Oxide).

  The counter substrate 3 includes a glass substrate 31, a color filter 32, and a touch detection electrode TDL. The color filter 32 is formed on one surface of the glass substrate 31. The color filter 32 is configured by periodically arranging, for example, three color filter layers of red (R), green (G), and blue (B), and each display pixel has R, G, and B color filters. Three colors are associated as one set. A touch detection electrode TDL is formed on the other surface of the glass substrate 31. The touch detection electrode TDL is an electrode made of, for example, ITO and having translucency. A polarizing plate 35 is disposed on the touch detection electrode TDL.

  The liquid crystal layer 6 functions as a display function layer, and modulates the light passing therethrough according to the state of the electric field. This electric field is formed by a potential difference between the voltage of the drive electrode COML and the voltage of the pixel electrode 22. For the liquid crystal layer 6, a liquid crystal in a transverse electric field mode such as FFS (fringe field switching) or IPS (in-plane switching) is used.

  An alignment film is provided between the liquid crystal layer 6 and the pixel substrate 2 and between the liquid crystal layer 6 and the counter substrate 3, and an incident side polarizing plate is provided on the lower surface side of the pixel substrate 2. Although not shown, the illustration is omitted here.

  FIG. 7 illustrates a configuration example of a pixel structure in the liquid crystal display device 20. The liquid crystal display device 20 has a plurality of pixels Pix arranged in a matrix. Each pixel Pix includes three subpixels SPix. These three subpixels SPix are arranged so as to correspond to the three colors (RGB) of the color filter 32 shown in FIG. The sub-pixel SPix has a TFT element Tr and a liquid crystal element LC. The TFT element Tr is composed of a thin film transistor. In this example, the TFT element Tr is composed of an n-channel MOS (Metal Oxide Semiconductor) TFT. The source of the TFT element Tr is connected to the pixel signal line SGL, the gate is connected to the scanning signal line GCL, and the drain is connected to one end of the liquid crystal element LC. The liquid crystal element LC has one end connected to the drain of the TFT element Tr and the other end connected to the drive electrode COML.

  The sub-pixel SPix is connected to another sub-pixel SPix belonging to the same row of the liquid crystal display device 20 by the scanning signal line GCL. The scanning signal line GCL is connected to the gate driver 12, and the scanning signal Vscan is supplied from the gate driver 12. The subpixel SPix is connected to another subpixel SPix belonging to the same column of the liquid crystal display device 20 by the pixel signal line SGL. The pixel signal line SGL is connected to the selection switch unit 14, and the pixel signal Vpix is supplied from the selection switch unit 14.

  Further, the sub-pixel SPix is connected to another sub-pixel SPix belonging to the same row of the liquid crystal display device 20 by the drive electrode COML. The drive electrode COML is connected to the drive electrode driver 16, and the drive signal Vcom (DC drive signal VcomDC) is supplied from the drive electrode driver 16.

  With this configuration, in the liquid crystal display device 20, the gate driver 12 drives the scanning signal lines GCL so as to perform line sequential scanning in a time division manner, whereby one horizontal line is sequentially selected, and the pixels Pix belonging to the one horizontal line are selected. On the other hand, when the source driver 13 and the selection switch unit 14 supply the pixel signal Vpix, display is performed for each horizontal line.

  FIG. 8 is a perspective view illustrating a configuration example of the touch detection device 30. The touch detection device 30 includes a drive electrode COML provided on the pixel substrate 2 and a touch detection electrode TDL provided on the counter substrate 3. The drive electrode COML is divided into a plurality of striped electrode patterns extending in the left-right direction in the figure. When performing the touch detection operation, the AC drive signal VcomAC is sequentially supplied to each electrode pattern by the drive electrode driver 16, and the scan drive is sequentially performed in a time division manner as will be described later. The touch detection electrode TDL includes a striped electrode pattern extending in a direction orthogonal to the extending direction of the electrode pattern of the drive electrode COML. Each electrode pattern of the touch detection electrode TDL is connected to an input of the LPF unit 42 of the touch detection unit 40. The electrode patterns intersecting with each other by the drive electrode COML and the touch detection electrode TDL form a capacitance at the intersection.

  With this configuration, in the touch detection device 30, when the drive electrode driver 16 applies the AC drive signal VcomAC to the drive electrode COML, the touch detection signal Vdet is output from the touch detection electrode TDL so that touch detection is performed. It has become. That is, the drive electrode COML corresponds to the drive electrode E1 in the basic principle of touch detection shown in FIGS. 1 to 3, the touch detection electrode TDL corresponds to the touch detection electrode E2, and the touch detection device 30 is Touch is detected according to this basic principle. As shown in FIG. 8, the electrode patterns intersecting each other constitute a capacitive touch sensor in a matrix. Therefore, by scanning the entire touch detection surface of the touch detection device 30, it is possible to detect the position where the contact or proximity of the external proximity object has occurred.

  FIG. 9 schematically shows the touch detection scanning. FIG. 9 shows an application operation of the AC drive signal VcomAC to each of the drive electrode blocks B1 to B20 when the display screen / touch detection surface is configured by 20 drive electrode blocks B1 to B20. The drive signal application block BAC indicates the drive electrode block B to which the AC drive signal VcomAC is applied, and the DC drive signal VcomDC is applied to the other drive electrode blocks B. As shown in FIG. 9, the drive electrode driver 16 sequentially selects the drive electrode block B that is the target of the touch detection operation, applies the AC drive signal VcomAC, and scans all the drive electrode blocks B. At that time, as will be described later, the drive electrode driver 16 applies an AC drive signal VcomAC to each drive electrode block B over a plurality of predetermined horizontal periods. In this example, for convenience of explanation, the number of drive electrode blocks B is set to 20. However, the present invention is not limited to this.

  FIG. 10 schematically shows display scanning and touch detection scanning. In the display panel 1 with a touch detection function, the gate driver 12 drives the scanning signal lines GCL so as to scan the scanning signal lines GCL in a time-sequential manner, thereby performing the display scanning Scan. Are sequentially selected and driven to perform touch detection scanning Scan. In this example, the touch detection scan Scant is performed at a scanning speed twice that of the display scan Scand. Thus, in the display panel 1 with a touch detection function, by making the scanning speed of touch detection faster than the display scanning, it is possible to immediately respond to a touch by an external proximity object, and improve the response characteristics for touch detection. Be able to. However, the present invention is not limited to this. For example, the touch detection scanning Scan may be performed at a scanning speed that is twice or more that of the display scanning Scan, or at a scanning speed that is twice or less that of the display scanning Scan. It may be performed.

(Drive signal generator 15 and drive electrode driver 16)
FIG. 11 illustrates a configuration example of the drive signal generation unit 15. The drive signal generation unit 15 includes a high level voltage generation unit 61, a low level voltage generation unit 62, buffers 63 to 65, and a switching circuit 66.

  The high level voltage generator 61 generates a high level voltage of the AC drive signal VcomAC. The low level voltage generator 62 generates a DC voltage of the DC drive signal VcomDC. The voltage generated by the low level voltage generator 62 is also used as a low level voltage of the AC drive signal VcomAC. The buffer 63 outputs the voltage supplied from the high-level voltage generation unit 61 while performing impedance conversion, and supplies the voltage to the switching circuit 66. The buffer 64 outputs the voltage supplied from the low-level voltage generation unit 62 while performing impedance conversion, and supplies the voltage to the switching circuit 66. The switching circuit 66 generates an AC drive signal VcomAC based on the Vcom control signal EXVCOM. Specifically, the switching circuit 66 outputs the voltage supplied from the buffer 63 when the Vcom control signal EXVCOM is at a high level, and is supplied from the buffer 64 when the Vcom control signal EXVCOM is at a low level. The output voltage is output. The buffer 65 outputs the voltage supplied from the low level voltage generation unit 62 as the DC drive signal VcomDC while performing impedance conversion. The buffers 63 to 65 are configured by, for example, a voltage follower.

  FIG. 12 illustrates a configuration example of the drive electrode driver 16. The drive electrode driver 16 includes a scanning control unit 51, a touch detection scanning unit 52, and a driving unit 530. The drive unit 530 has 20 drive units 53 (1) to 53 (20). Hereinafter, when referring to any one of the 20 drive units 53 (2) to 53 (20), the drive unit 53 is simply used.

  The scanning control unit 51 supplies a control signal to the touch detection scanning unit 52 based on the control signal supplied from the control unit 11. The scanning control unit 51 also has a function of supplying the drive unit 530 with a Vcom selection signal VCOMSEL for instructing which of the DC drive signal VcomDC and the AC drive signal VcomAC is supplied to the drive electrode COML. Have.

  The touch detection scanning unit 52 includes a shift register, and generates a scanning signal St for selecting the driving electrode COML to which the AC driving signal VcomAC is applied. Specifically, the touch detection scanning unit 52 generates a plurality of scanning signals St each corresponding to each drive electrode block B based on the control signal supplied from the scanning control unit 51 as described later. For example, when the touch detection scanning unit 52 supplies a high level signal to the kth driving unit 53 (k) as the kth scanning signal St (k), the driving unit 53 (k) An AC drive signal VcomAC is applied to a plurality of drive electrodes COML belonging to the second drive electrode block B (k).

  Based on the scanning signal St supplied from the touch detection scanning unit 52 and the Vcom selection signal VCOMSEL supplied from the scanning driving unit 51, the driving unit 530 receives the direct current driving signal VcomDC supplied from the driving signal generation unit 15 or the alternating current. The drive signal VcomAC is applied to the drive electrode COML. The drive units 53 are provided one by one corresponding to the output signal of the touch detection scanning unit 52, and apply the drive signal Vcom to the corresponding drive electrode block B.

  The drive unit 53 includes an AND circuit 54, an inverter 55, buffers 56 and 57, and switches SW1 and SW2. The AND circuit 54 generates and outputs a logical product (AND) of the scanning signal St supplied from the touch detection scanning unit 52 and the Vcom selection signal VCOMSEL supplied from the scanning control unit 51. The inverter 55 generates and outputs an inverted logic of the output signal of the AND circuit 54. The buffer 56 has a function of amplifying the signal supplied from the AND circuit 54 to an amplitude level at which the switch SW1 can be turned on / off. The switch SW1 is ON / OFF controlled based on a signal supplied from the buffer 56, and is supplied with an AC drive signal VcomAC at one end and connected to a plurality of drive electrodes COML constituting the drive electrode block B at the other end. Has been. The buffer 57 has a function of amplifying the signal supplied from the inverter 55 to an amplitude level at which the switch SW2 can be controlled on and off. The switch SW2 is ON / OFF controlled based on a signal supplied from the buffer 57, and a DC drive signal VcomDC is supplied to one end and the other end is connected to the other end of the switch SW1.

  With this configuration, when the scanning signal St is at a high level, the drive unit 53 outputs the AC drive signal VcomAC as the drive signal Vcom when the Vcom selection signal VCOMSEL is at a high level, and the Vcom selection signal VCOMSEL is at a low level. At this time, the DC drive signal VcomDC is output as the drive signal Vcom. The drive unit 53 outputs the DC drive signal VcomDC as the drive signal Vcom when the scanning signal St is at a low level. The drive unit 53 supplies the drive signal Vcom output in this way to a plurality of drive electrodes COML constituting the drive electrode block B corresponding to the drive unit 53.

  Here, the liquid crystal element LC corresponds to a specific example of “display element” in the present disclosure. The drive electrode driver 16 corresponds to a specific example of a “drive unit” in the present disclosure. The high level voltage generation unit 61 and the buffer 63 correspond to a specific example of “first voltage generation unit” in the present disclosure. The low level voltage generation unit 62 corresponds to a specific example of “second voltage generation unit” in the present disclosure. The buffer 64 corresponds to a specific example of “a buffer circuit” in the present disclosure.

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

(Overview of overall operation)
First, with reference to FIG. 4, an outline of the overall operation of the display panel with a touch detection function 1 will be described. The control unit 11 supplies control signals to the gate driver 12, the source driver 13, the drive signal generation unit 15, the drive electrode driver 16, and the touch detection unit 40 based on the video signal Vdisp supplied from the outside. Control these to operate in synchronization with each other. The gate driver 12 supplies the scanning signal Vscan to the liquid crystal display device 20, and sequentially selects one horizontal line that is a display driving target. The source driver 13 generates a pixel signal Vsig obtained by multiplexing the pixel signal Vpix and a switch control signal Vsel corresponding to the pixel signal Vsig, and supplies the generated signal to the selection switch unit 14. The selection switch unit 14 separates and generates the pixel signal Vpix based on the pixel signal Vsig and the switch control signal Vsel, and supplies the pixel signal Vpix to each sub-pixel SPix constituting one horizontal line. The drive signal generator 15 generates a DC drive signal VcomDC and an AC drive signal VcomAC. The drive electrode driver 16 sequentially applies the AC drive signal VcomAC to the drive electrode block B, and applies the DC drive signal VcomDC to the drive electrode COML to which the AC drive signal VcomAC is not applied. The display device with a touch detection function 10 performs a display operation and a touch detection operation, and outputs a touch detection signal Vdet from the touch detection electrode TDL. The LPF unit 42 removes a high frequency component (noise component) included in the touch detection signal Vdet, extracts the touch component, and outputs it. The A / D converter 43 converts the analog signal output from the LPF unit 42 into a digital signal. The signal processing unit 44 detects the presence / absence of a touch on the display device 10 with a touch detection function based on the output signal of the A / D conversion unit 43. The coordinate extraction unit 45 obtains the touch panel coordinates when touch detection is performed in the signal processing unit 44. The detection timing control unit 46 controls the LPF unit 42, the A / D conversion unit 43, the signal processing unit 44, and the coordinate extraction unit 45 to operate in synchronization.

(Detailed operation)
Next, detailed operation of the display panel with a touch detection function 1 will be described.

  13A and 13B show examples of timing waveforms of the display panel 1 with a touch detection function. FIG. 13A shows the waveform of the AC drive signal VcomAC, FIG. 13B shows the waveform of the DC drive signal VcomDC, and FIG. Shows the waveform of the scanning signal Vscan, (D) shows the waveform of the pixel signal Vsig, (E) shows the waveform of the switch control signal Vsel, (F) shows the waveform of the pixel signal Vpix, and (G) shows The waveform of the Vcom selection signal VCOMSEL is shown, (H) shows the waveform of the drive signal Vcom, and (I) shows the waveform of the touch detection signal Vdet.

  In the display panel 1 with a touch detection function, the touch detection operation and the display operation are performed in each one horizontal period (1H). In the display operation, the gate driver 12 performs display scanning by sequentially applying the scanning signal Vscan to the scanning signal line GCL. In the touch detection operation, the drive electrode driver 16 performs touch detection scanning by sequentially applying the AC drive signal VcomAC for each drive electrode block B, and the touch detection unit 40 outputs a touch detection signal output from the touch detection electrode TDL. A touch is detected based on Vdet. Details will be described below.

  First, after one horizontal period (1H) starts at timing t0, the scanning control unit 51 of the drive electrode driver 16 changes the voltage of the Vcom selection signal VCOMSEL from low level to high level at timing t1 (FIG. 13 ( G)). Thereby, in the drive electrode driver 16, in the k-th drive unit 53 (k) related to the touch detection operation, the switch SW1 is turned on and the switch SW2 is turned off, and the AC drive generated by the drive signal generation unit 15 is performed. The signal VcomAC (FIG. 13A) is supplied as a drive signal Vcom (B (k)) to the drive electrode COML constituting the corresponding kth drive electrode block B (k) via the switch SW1. Applied (FIG. 13H). In the drive units 53 other than the drive unit 53 (k), the switch SW1 is turned off and the switch SW2 is turned on, and the DC drive signal VcomDC generated by the drive signal generation unit 15 (FIG. 13 ( B)) is applied to the drive electrode COML constituting the corresponding drive electrode block B through the switch SW2 (FIG. 13 (H)).

  Next, the drive signal generation unit 15 changes the voltage of the AC drive signal VcomAC from a low level to a high level at timing t2 (FIG. 13A). Specifically, in the drive signal generator 15, the buffer 63 supplies current via the switching circuit 66 based on the Vcom control signal EXVCOM, whereby the voltage of the AC drive signal VcomAC changes from low level to high level. To do. Accordingly, the drive signal Vcom (B (k)) applied to the kth drive electrode block B (k) also changes from the low level to the high level (FIG. 13 (H)). This drive signal Vcom (B (k)) is transmitted to the touch detection electrode TDL via the electrostatic capacitance, and the touch detection signal Vdet changes (FIG. 13 (I)).

  Next, the A / D conversion unit 43 of the touch detection unit 40 A / D converts the output signal of the LPF unit 42 to which the touch detection signal Vdet is input at the sampling timing ts (FIG. 13 (I)). As will be described later, the signal processing unit 44 of the touch detection unit 40 performs touch detection based on the A / D conversion results collected in a plurality of horizontal periods.

  Next, the drive signal generator 15 changes the voltage of the AC drive signal VcomAC from a high level to a low level at timing t3 (FIG. 13A). Specifically, in the drive signal generation unit 15, the buffer 64 sinks current via the switching circuit 66 based on the Vcom control signal EXVCOM, whereby the voltage of the AC drive signal VcomAC changes from a high level to a low level. To do. Accordingly, the drive signal Vcom (B (k)) applied to the kth drive electrode block B (k) also changes from the high level to the low level (FIG. 13 (H)), and the touch detection signal Vdet is changed. It changes (FIG. 13 (I)).

  Next, the scanning control unit 51 of the drive electrode driver 16 changes the voltage of the Vcom selection signal VCOMSEL from a high level to a low level at timing t4 (FIG. 13G). Thus, in the drive electrode driver 16, in the drive unit 53 (k), the switch SW1 is turned off and the switch SW2 is turned on, and the direct current drive signal VcomDC generated by the drive signal generation unit 15 (FIG. 13B). ) Is applied as a drive signal Vcom (B (k)) to the drive electrode COML constituting the corresponding drive electrode block B (k) through the switch SW2 (FIG. 13 (H)).

  Next, at timing t5, the gate driver 12 applies the scanning signal Vscan to the n-th scanning signal line GCL (n) related to the display operation, and the scanning signal Vscan (n) is changed from a low level to a high level. (FIG. 13C). Then, the source driver 13 and the selection switch unit 14 apply the pixel signal Vpix to the pixel signal line SGL (FIG. 13F), and one horizontal line related to the scanning signal line GCL (n) of the n-th row. The pixel Pix is displayed.

  Specifically, first, the gate driver 12 selects one horizontal line related to the display operation by changing the scanning signal Vscan (n) from the low level to the high level at the timing t5. Then, the source driver 13 supplies the pixel voltage VR for the red sub-pixel SPix to the selection switch unit 14 as the pixel signal Vsig (FIG. 13D), and the period during which the pixel voltage VR is supplied The switch control signal VselR that becomes a high level is generated and supplied to the selection switch unit 14 (FIG. 13E). Then, the selection switch unit 14 turns on the switch SWR during the period when the switch control signal VselR is at a high level (the writing period PW), whereby the pixel voltage VR supplied from the source driver 13 is applied to the pixel signal Vsig. And is supplied as a pixel signal VpixR to the red sub-pixel SPix related to one horizontal line through the pixel signal line SGL (FIG. 13F). Since the pixel signal line SGL is in a floating state after the switch SWR is turned off, the voltage of the pixel signal line SGL is held (FIG. 13F). Similarly, the source driver 13 supplies the pixel voltage VG for the green sub-pixel Spix to the selection switch unit 14 together with the corresponding switch control signal VselG (FIGS. 13D and 13E), and the selection switch unit 14 separates the pixel voltage VG from the pixel signal Vsig based on the switch control signal VselG, and supplies it as a pixel signal VpixG to the green sub-pixel SPix related to one horizontal line via the pixel signal line SGL. (FIG. 13F). Thereafter, similarly, the source driver 13 supplies the pixel voltage VB for the blue sub-pixel Spix to the selection switch unit 14 together with the corresponding switch control signal VselB (FIGS. 13D and 13E) and selects the pixel voltage VB. The switch unit 14 separates the pixel voltage VB from the pixel signal Vsig based on the switch control signal VselB, and supplies the pixel signal VpixB to the blue subpixel SPix related to one horizontal line via the pixel signal line SGL. (FIG. 13F).

  Next, the gate driver 12 changes the scanning signal Vscan (n) of the n-th scanning signal line GCL from the high level to the low level at timing t6 (FIG. 13C). Thereby, the sub-pixel Spix of one horizontal line related to the display operation is electrically disconnected from the pixel signal line SGL.

  At timing t10, one horizontal period ends and a new one horizontal period starts.

  Thereafter, by repeating the above-described operation, the display panel 1 with a touch detection function performs a display operation on the entire display screen by line-sequential scanning, and scans each drive electrode block B as shown below. Then, a touch detection operation on the entire touch detection surface is performed.

  14A and 14B show an example of the operation of touch detection scanning. FIG. 14A shows the waveform of the AC drive signal VcomAC, FIG. 14B shows the waveform of the DC drive signal VcomDC, and FIG. 14C shows the Vcom selection signal VCOMSEL. (D) shows the waveform of the scanning signal St, (E) shows the waveform of the drive signal Vcom, and (F) shows the waveform of the touch detection signal Vdet.

  As shown in FIG. 14, the drive electrode driver 16 sequentially applies the AC drive signal VcomAC to the corresponding drive electrode block B based on the scanning signal St (FIG. 14D) generated by the touch detection scanning unit 52. By doing so (FIG. 14E), touch detection scanning is performed. At that time, the drive electrode driver 16 applies the AC drive signal VcomAC to each drive electrode block B over a plurality of predetermined horizontal periods (FIG. 14E). The touch detection unit 40 samples the touch detection signal Vdet based on the AC drive signal VcomAC in each horizontal period, and performs signal processing after sampling in the last horizontal period of the predetermined plurality of horizontal periods is completed. The unit 44 detects the presence / absence of a touch on the area corresponding to the drive electrode block B based on the plurality of sampling results. As described above, since touch detection is performed based on a plurality of sampling results, it is possible to statistically analyze the sampling results, and to suppress deterioration of the S / N ratio due to variations in the sampling results. And the accuracy of touch detection can be increased.

(Comparative example)
Next, the operation of the present embodiment will be described in comparison with the comparative example. In this comparative example, the drive signal generation unit generates two DC drive signals of a high level and a low level, and the drive electrode driver switches the two DC drive signals and applies them to the drive electrode COML. It is. Other configurations are the same as those of the present embodiment (FIG. 4 and the like).

  FIG. 15 illustrates a configuration example of the drive signal generation unit 15R according to this comparative example. The drive signal generator 15R generates two DC drive signals VcomH and VcomDC. The DC drive signal VcomH is generated by the high level voltage generator 61 and output through the buffer 63. The DC drive signal VcomDC is generated by the low level voltage generator 62 and is output via the buffer 65.

  FIG. 16 illustrates a configuration example of the drive electrode driver 16R according to this comparative example. The drive electrode driver 16R has a scanning control unit 51R. The scanning control unit 51R supplies the drive unit 530 with a Vcom selection signal VCOMSELR for instructing which of the two DC drive signals VcomH and VcomDC is supplied to the drive electrode COML.

  In the drive electrode driver 16R, as shown in FIG. 16, the DC drive signal VcomH is supplied to one end of the switch SW1. With this configuration, when the scanning signal St is at a high level, the drive unit 53 outputs the DC drive signal VcomH as the drive signal Vcom when the Vcom selection signal VCOMSELR is at a high level, and the Vcom selection signal VCOMSELR is at a low level. At this time, the DC drive signal VcomDC is output as the drive signal Vcom.

  17A and 17B show examples of timing waveforms of the display panel with a touch detection function according to this comparative example. FIG. 17A shows the waveform of the DC drive signal VcomH, and FIG. 17B shows the waveform of the DC drive signal VcomDC. (C) shows the waveform of the scanning signal Vscan, (D) shows the waveform of the pixel signal Vsig, (E) shows the waveform of the switch control signal Vsel, (F) shows the waveform of the pixel signal Vpix, (G) shows the waveform of the Vcom selection signal VCOMSELR, (H) shows the waveform of the drive signal Vcom, and (I) shows the waveform of the touch detection signal Vdet.

  The scanning control unit 51R of the drive electrode driver 16R changes the voltage of the Vcom selection signal VCOMSELR from the low level to the high level at the timing t11 (FIG. 17G). As a result, in the drive electrode driver 16R, in the k-th drive unit 53 (k) related to the touch detection operation, the switch SW1 is turned on and the switch SW2 is turned off, and the DC drive generated by the drive signal generation unit 15R is performed. The signal VcomH (FIG. 17A) is supplied as a drive signal Vcom (B (k)) to the drive electrode COML constituting the corresponding kth drive electrode block B (k) via the switch SW1. Applied (FIG. 17H). Specifically, when the buffer 63 of the drive signal generation unit 15R supplies current to these drive electrodes COML, the drive signal Vcom (B (k)) changes from a low level to a high level. In the drive units 53 other than the drive unit 53 (k), the switch SW1 is turned off and the switch SW2 is turned on, and the DC drive signal VcomDC generated by the drive signal generation unit 15 (FIG. 17 ( B)) is applied to the drive electrode COML constituting the corresponding drive electrode block B through the switch SW2 (FIG. 17H). Then, the A / D conversion unit 43 of the touch detection unit 40 performs A / D conversion on the output signal of the LPF unit 42 to which the touch detection signal Vdet is input at the sampling timing ts (FIG. 17I).

  Next, the scanning control unit 51R of the drive electrode driver 16R changes the voltage of the Vcom selection signal VCOMSELR from the high level to the low level at timing t12 (FIG. 17G). Thereby, in the drive electrode driver 16R, in the drive unit 53 (k), the switch SW1 is turned off and the switch SW2 is turned on, and the DC drive signal VcomDC generated by the drive signal generation unit 15R (FIG. 17B). ) Is applied as a drive signal Vcom (B (k)) to the drive electrode COML constituting the corresponding drive electrode block B (k) through the switch SW2 (FIG. 17H). Specifically, the buffer 65 of the drive signal generator 15R sinks current from these drive electrodes COML, so that the drive signal Vcom (B (k)) changes from a high level to a low level.

  At this time, the buffer 65 of the drive signal generation unit 15R drives all the drive electrodes COML via the switch SW2 of the drive unit 530 of the drive electrode buffer 16R. That is, since the buffer 65 has a large load, there is a possibility that it cannot be driven sufficiently. In this case, the charge charged in the drive electrode COML of the drive electrode block B (k) by the application of the DC drive signal VcomH is transferred via the switch SW2 of the drive unit 53 (k) after timing t12. As shown in FIG. 17H, the drive signals Vcom (Vcom (B (k-1)), Vcom (B) applied to these drive electrode blocks B are moved to the drive electrode block B of FIG. (k)), Vcom (B (k + 1), etc.) rises (waveform portion WR). Then, the buffer 65 sinks this electric charge, so that the drive signal Vcom gradually converges to the voltage level of the DC drive signal VcomDC. When the convergence time is long and extends to the writing period PW, for example, writing of the pixel signal Vpix to the pixel in the writing period PW becomes insufficient, and the image quality may be deteriorated.

  On the other hand, in the display panel with a touch detection function according to the present embodiment, as shown in FIG. 13H, after the AC drive signal VcomAC changes from the high level to the low level at the timing t3, the display is driven at the timing t4. In the unit 53 (k), the drive signal supplied to the drive electrode COML is switched from the AC drive signal VcomAC to the DC drive signal VcomDC by turning off the switch SW1 and turning on the switch SW2.

  Thereby, first, when the AC drive signal VcomAC changes from the high level to the low level at the timing t3, in the drive signal generation unit 15, the buffer 64 different from the buffer 65 that generates the DC drive signal VcomDC sinks the current. Therefore, the possibility that the change of the AC drive signal VcomAC affects the DC drive signal VcomDC can be reduced. That is, noise in the DC drive signal VcomDC supplied to the horizontal line on which the display operation is performed can be suppressed, so that deterioration in image quality can be suppressed.

  Further, immediately before the timing t4, the potential of the drive electrode block B (k) (low level voltage in the AC drive signal VcomAC) and the potential of the other drive electrode block B (k) (DC voltage of the DC drive signal VcomDC). Since they are substantially equal, at time t4, there is almost no movement of charge after the switch SW2 is turned on, and the rise in the voltage of the drive signal Vcom (B (k)) as in the waveform portion WR in the comparative example is reduced. And a reduction in image quality can be suppressed.

[effect]
As described above, in the present embodiment, the AC drive signal and the DC drive signal are selectively driven with respect to the drive electrode, and the AC drive signal is changed after the AC drive signal changes from the high level to the low level. Since the signal is switched to the DC drive signal, it is possible to suppress deterioration in image quality.

  In the present embodiment, since a buffer for supplying a low level of the AC drive signal and a buffer for supplying the DC drive signal are provided separately, it is possible to suppress deterioration in image quality.

[Modification 1-1]
In the above embodiment, the drive signal generation unit 15 is configured as shown in FIG. 11, but is not limited to this. For example, as shown in FIG. 18, the buffer 64A that generates the low level of the AC drive signal VcomAC may receive the DC drive signal VcomDC as an input. Here, the low-level voltage generation unit 62 and the buffer 65 correspond to a specific example of “second voltage generation unit” in the present disclosure. The buffer 64A corresponds to a specific example of “a buffer circuit” in the present disclosure. Even in this case, since it is possible to reduce the possibility that noise caused by the AC drive signal VcomAC affects the DC drive signal VcomDC, it is possible to suppress deterioration in image quality.

[Modification 1-2]
In the above embodiment, the drive electrode driver 16 is driven for each drive electrode block B made up of a predetermined number of drive electrodes COML. However, the present invention is not limited to this, and instead, for example, As shown in FIG. 19, it may be driven for each drive electrode COML. In this case, the drive unit 530B includes the same number of drive units 53 as the total number of drive electrodes COML, and the touch detection scanning unit 52B supplies a scanning signal St to the drive unit 530B.

[Modification 1-3]
In the above-described embodiment, the drive electrode COML is driven and scanned for each drive electrode block B including the predetermined number of drive electrodes COML. However, the present invention is not limited to this, and instead, for example, the predetermined number The drive electrodes COML may be driven simultaneously, and scanning may be performed by shifting the drive electrodes COML to be driven one by one. The details will be described below.

  FIG. 20 schematically illustrates an operation example of the drive electrode driver 16C according to the present modification. The drive electrode driver 16C applies the AC drive signal VcomAC to a predetermined number of drive electrodes COML simultaneously. Specifically, the drive electrode driver 16C applies the AC drive signal VcomAC simultaneously to a predetermined number (in this example, 5) of drive electrodes COML (drive signal application electrode LAC). Then, the drive electrode driver 16C performs touch detection scanning by shifting the drive electrodes COML to which the AC drive signal VcomAC is applied one by one. Such touch detection scanning can be realized, for example, by using the drive electrode driver 16B shown in FIG. 19 and propagating a wide pulse in the shift register of the touch detection scanning unit 52B. In this example, the AC drive signal VcomAC is simultaneously applied to the five drive electrodes COML. However, the present invention is not limited to this. Instead, the drive electrode COML is applied to four or less drive electrodes COML. On the other hand, the AC drive signal VcomAC may be applied simultaneously. In this example, the drive electrodes COML to which the AC drive signal VcomAC is applied are shifted one by one. However, the present invention is not limited to this, and instead, the number may be shifted by two or more. .

[Modification 1-4]
In the above embodiment, as shown in FIG. 13, after the voltage of the Vcom selection signal VCOMSEL changes from low level to high level at timing t1, the AC drive signal VcomAC changes from low level to high level at timing t2. However, the present invention is not limited to this. For example, as shown in FIG. 21, after the AC drive signal VcomAC changes from a low level to a high level at timing t21, the voltage of the Vcom selection signal VCOMSEL changes from a low level to a high level at timing t22. Good.

<3. Second Embodiment>
Next, the display panel 7 with a touch detection function according to the second embodiment will be described. In the present embodiment, the selection method of the drive signal when the DC drive signal VcomDC and the AC drive signal VcomAC are selected and supplied to the drive electrode COML is different. In addition, the same code | symbol is attached | subjected to the component substantially the same as the display panel 1 with a touch detection function based on the said 1st Embodiment, and description is abbreviate | omitted suitably.

  FIG. 22 illustrates a configuration example of the drive electrode driver 18 according to the display panel 7 with a touch detection function. The drive electrode driver 18 includes a scan control unit 71 and a drive unit 730.

  The scanning control unit 71 supplies a control signal to the touch detection scanning unit 52 based on the control signal supplied from the control unit 11.

  The drive unit 730 applies the drive signal Vcom (the DC drive signal VcomDC and the AC drive signal VcomAC) to the drive electrode COML based on the scanning signal St supplied from the touch detection scanning unit 52. The drive unit 73 includes an inverter 55, buffers 56 and 57, and switches SW1 and SW2. That is, the drive unit 73 does not have the AND circuit 54 unlike the drive unit 53 according to the above embodiment. With this configuration, the drive unit 73 outputs the AC drive signal VcomAC as the drive signal Vcom when the scanning signal St is at a high level, and the DC drive signal VcomDC as the drive signal when the scan signal St is at a low level. Output as Vcom.

  23A and 23B show examples of timing waveforms of the display panel 7 with a touch detection function. FIG. 23A shows the waveform of the AC drive signal VcomAC, FIG. 23B shows the waveform of the DC drive signal VcomDC, and FIG. Shows the waveform of the scanning signal Vscan, (D) shows the waveform of the pixel signal Vsig, (E) shows the waveform of the switch control signal Vsel, (F) shows the waveform of the pixel signal Vpix, and (G) shows The waveform of the drive signal Vcom is shown, and (H) shows the waveform of the touch detection signal Vdet.

  First, when one horizontal period (1H) starts at timing t0, the drive electrode driver 18 supplies the AC drive signal VcomAC to the drive electrode COML related to touch detection (FIG. 23G). Specifically, in the drive electrode driver 18, in the k-th drive unit 73 (k) related to the touch detection operation, the switch SW1 is turned on and the switch SW2 is turned off, and the drive signal generation unit 15 generates the switch SW1. The AC drive signal VcomAC (FIG. 23A) is supplied via the switch SW1 to the drive electrode COML constituting the corresponding kth drive electrode block B (k). ) (FIG. 23G).

  Next, the drive signal generation unit 15 changes the voltage of the AC drive signal VcomAC from a low level to a high level at timing t2 (FIG. 23A). Accordingly, the drive signal Vcom (B (k)) applied to the kth drive electrode block B (k) changes from the low level to the high level (FIG. 23 (G)). This drive signal Vcom (B (k)) is transmitted to the touch detection electrode TDL via the electrostatic capacitance, and the touch detection signal Vdet changes (FIG. 23 (H)). Then, the A / D conversion unit 43 of the touch detection unit 40 A / D converts the output signal of the LPF unit 42 to which the touch detection signal Vdet is input at the sampling timing ts (FIG. 23 (H)). Thereafter, the drive signal generation unit 15 changes the voltage of the AC drive signal VcomAC from a high level to a low level at timing t3 (FIG. 23A).

  Then, in the display panel with a touch detection function 7, after the timing t5, the display operation is performed as in the case of the display panel with a touch detection function 1 according to the first embodiment. In the display panel 7 with a touch detection function, the drive electrode driver 18 continues to apply the AC drive signal VcomAC as the drive signal Vcom (B (k)) to the drive electrode COML related to touch detection (FIG. 23). (G)).

  24A and 24B show an example of touch detection scanning operation in the display panel 7 with a touch detection function. FIG. 24A shows the waveform of the AC drive signal VcomAC, and FIG. 24B shows the waveform of the DC drive signal VcomDC. (C) shows the waveform of the scanning signal St, (D) shows the waveform of the drive signal Vcom, and (E) shows the waveform of the touch detection signal Vdet.

  As shown in FIG. 24, the drive electrode driver 18 sequentially applies the AC drive signal VcomAC to the corresponding drive electrode block B based on the scanning signal St (FIG. 24C) generated by the touch detection scanning unit 52. By doing so (FIG. 24D), touch detection scanning is performed. At that time, for example, the drive electrode driver 18 always supplies the AC drive signal VcomAC to the corresponding kth drive electrode block B (k) over a period in which the kth scan signal St (k) is at a high level. Continue to supply. That is, in the first embodiment, as shown in FIG. 14E, AC driving is performed only during a period in which the Vcom selection signal VCOMSEL is at a high level in a period in which the scanning signal St (k) is at a high level. Although the signal VcomAC is applied, in the present embodiment, as shown in FIG. 24D, the AC drive signal VcomAC is always applied during a period in which the scanning signal St (k) is at a high level.

  The DC drive signal VcomDC or the AC drive signal VcomAC is applied to the drive electrode COML of one horizontal line related to the display operation. Specifically, when the drive electrode COML of one horizontal line related to the display operation is not included in the drive detection block B related to the touch detection operation, the DC drive signal VcomDC is applied to the drive electrode COML. On the other hand, for example, at the timing W1 in FIG. 10, the drive electrode COML of one horizontal line related to the display operation is included in the drive detection block B related to the touch detection operation. In this case, the drive electrode COML Is applied with an AC drive signal VcomAC. Since the DC voltage of the DC drive signal VcomDC and the low level voltage of the AC drive signal VcomAC are generated by the low level voltage generator 62 of the drive signal generator 15 as shown in FIG. It is. Thus, the voltage of the drive electrode COML related to the one horizontal line is almost equal between the case where one horizontal line related to the display operation corresponds to the drive detection block B related to the touch detection operation and the other cases. Since the pixel signals are written in substantially the same manner in the writing period PW, it is possible to suppress deterioration in image quality.

  If the direct current voltage of the direct current drive signal VcomDC and the low level voltage of the alternating current drive signal VcomAC are slightly different due to the difference in performance between the buffers 64 and 65 (FIG. 11), one horizontal line related to the display operation is displayed. Since writing to the pixel is different between when the DC drive signal VcomDC is supplied to the drive electrode COML and when the AC drive signal VcomAC is supplied, the image quality may be deteriorated. In this case, it is desirable to apply the AC drive signal VcomAC to the drive electrode COML in a period other than the write period PW, like the display panel with a touch detection function 1 of the first embodiment.

  As described above, in the present embodiment, since the drive signal supplied to the drive electrode is selected based on only the scan signal St in the embodiment, the configuration of the scan control unit and the drive unit is simplified. be able to. Other effects are the same as in the case of the first embodiment.

[Modification 2]
Also in the above-described embodiment, the drive signal generation unit 15 may be configured as illustrated in FIG. 18, for example, as in Modification 1-1 of the first embodiment. Further, like the modification 1-2 of the first embodiment, the drive electrode driver 18 may drive for each drive electrode COML. In addition, as in Modification 1-3 of the first embodiment, touch detection scanning may be performed as shown in FIG.

<3. Application example>
Next, with reference to FIGS. 25 to 29, application examples of the display panel with a touch detection function described in the above embodiment and the modification will be described. The display panel with a touch detection function according to 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. is there. In other words, the display panel with a touch detection function according to the above-described embodiment and 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. It is.

(Application example 1)
FIG. 25 illustrates an appearance of a television device to which the display panel with a touch detection function according to the above-described embodiment or the like is applied. This television apparatus has, for example, a video display screen unit 510 including a front panel 511 and a filter glass 512. The video display screen unit 510 is formed by the display panel with a touch detection function according to the above-described embodiment and the like. It is configured.

(Application example 2)
FIG. 26 illustrates an appearance of a digital camera to which the display panel with a touch detection function 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, and the display unit 522 is a display panel with a touch detection function according to the above-described embodiment and the like. It is comprised by.

(Application example 3)
FIG. 27 illustrates an appearance of a notebook personal computer to which the display panel with a touch detection function 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 consists of a display panel with a detection function.

(Application example 4)
FIG. 28 illustrates an appearance of a video camera to which the display panel with a touch detection function 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. The display unit 544 includes a display panel with a touch detection function according to the above-described embodiment and the like.

(Application example 5)
FIG. 29 illustrates an appearance of a mobile phone to which the display panel with a touch detection function according to the above-described embodiment or 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 panel with a touch detection function according to the above-described embodiment and the like.

  The present technology has been described above with some embodiments and modifications, and application examples to electronic devices. However, the present technology is not limited to these embodiments and the like, and various modifications are possible. is there.

  For example, in the above embodiment and the like, as shown in FIG. 6, the drive electrode COML is formed on the TFT substrate 21, and the pixel electrode 22 is formed thereon via the insulating film 23. However, the present invention is not limited to this. Instead, for example, the pixel electrode 22 may be formed on the TFT substrate 21, and the drive electrode COML may be formed thereon via the insulating film 23.

  Further, for example, in the above-described embodiment, a liquid crystal display device using a liquid crystal in a horizontal electric field mode such as FFS and IPS and a touch detection device are integrated, but instead of this, TN (twisted nematic), VA A liquid crystal display device using a liquid crystal of various modes such as (vertical alignment) and ECB (electric field control birefringence) may be integrated with a touch detection device. When such a liquid crystal is used, a display device with a touch detection function can be configured as shown in FIG. FIG. 30 illustrates an example of a cross-sectional structure of a main part of a display device with a touch detection function 10D according to this modification, and illustrates a state where the liquid crystal layer 6B is sandwiched between the pixel substrate 2B and the counter substrate 3B. ing. The names and functions of the other parts are the same as those in FIG. In this example, unlike the case of FIG. 6, the drive electrode COML that is used for both display and touch detection is formed on the counter substrate 3B.

  Further, for example, in each of the above embodiments, a so-called in-cell type in which a liquid crystal display device and a capacitive touch detection device are integrated is not limited to this, and instead of this, for example, A so-called on-cell type in which a capacitive touch detection device is formed on the surface of the liquid crystal display device may be used. In the on-cell type, for example, when touch detection drive noise propagates from the touch detection device to the liquid crystal display device, the noise can be reduced by driving as in the above embodiment. The deterioration of the image quality of the liquid crystal display device can be suppressed.

  Further, for example, in each of the above embodiments, the display element is a liquid crystal element. However, the display element is not limited to this, and instead, for example, an EL (Electro Luminescence) element may be used.

  In addition, this technique can be set as the following structures.

(1) one or more display elements;
One or more drive electrodes;
One or more touch detection electrodes;
A display panel with a touch detection function, comprising: a drive unit that selectively applies a DC drive signal or an AC drive signal to the drive electrode.

(2) The display element performs a display writing operation in a writing period,
The AC drive signal has a pulse waveform that transitions from a first voltage to a second voltage corresponding to a DC voltage level of the DC drive signal at a transition timing that does not belong to the writing period.
The drive unit performs the touch detection drive by applying the AC drive signal to the drive electrode in an enable period to which the transition timing belongs, and applying the DC drive signal in a period other than the enable period. The display panel with a touch detection function according to (1).

(3) The AC driving signal is a pulse waveform having the first voltage in a pulse period different from the writing period and having the second voltage in a period other than the pulse period,
The display panel with a touch detection function according to (2), wherein the transition timing corresponds to an end timing of the pulse period.

(4) The display panel with a touch detection function according to (3), wherein the enable period is a period different from the writing period.

(5) The display panel with a touch detection function according to (3) or (4), wherein the enable period is a period including the pulse period.

(6) The plurality of display elements are arranged in a matrix and perform a display operation by line sequential scanning.
The display panel with a touch detection function according to (3), wherein the enable period corresponds to one or a plurality of continuous horizontal periods.

(7) It further includes a drive signal generation unit that generates the DC drive signal and the AC drive signal,
The drive signal generator is
A first voltage generator for generating the first voltage;
A second voltage generator for generating a voltage corresponding to a DC voltage level of the DC drive signal;
A buffer circuit that generates the second voltage based on an output voltage of the second voltage generator;
The display with a touch detection function according to any one of (1) to (6), including: a switching circuit that generates the AC drive signal by switching between the first voltage and the second voltage. panel.

(8) A touch detection unit is further provided,
The plurality of drive electrodes are formed to extend in a predetermined direction,
The plurality of touch detection electrodes are formed in a layer different from the plurality of drive electrodes so as to extend in a direction intersecting with the extension direction of the drive electrodes,
The drive unit sequentially selects one or more of the plurality of drive electrodes as a drive target electrode, performs the touch detection drive on the drive target electrode, and applies to the drive electrodes other than the drive target electrode Applying the DC drive signal to
The display panel with a touch detection function according to any one of (1) to (7), wherein the touch detection unit detects a touch based on an output signal from the touch detection electrode.

(9) The display element is:
A liquid crystal layer;
Any one of (1) to (8), including a pixel electrode formed between the liquid crystal layer and the drive electrode, or arranged to face the liquid crystal layer with the drive electrode interposed therebetween A display panel with a touch detection function described in Crab.

(10) The display element is:
A liquid crystal layer;
The display panel with a touch detection function according to any one of (1) to (8), including a pixel electrode disposed so as to face the drive electrode with the liquid crystal layer interposed therebetween.

(11) Display driving one or a plurality of display elements,
A method for driving a display panel with a touch detection function, wherein a DC drive signal or an AC drive signal is selectively applied to one or a plurality of drive electrodes.

(12) a display driver that drives one or more display elements;
A touch detection drive unit that selectively applies a DC drive signal or an AC drive signal to one or a plurality of drive electrodes.

(13) a display panel with a touch detection function;
A control unit that performs operation control using the display panel with a touch detection function,
The display panel with a touch detection function is:
One or more display elements;
One or more drive electrodes;
One or more touch detection electrodes;
An electronic device comprising: a drive unit that selectively applies a DC drive signal or an AC drive signal to the drive electrode.

  DESCRIPTION OF SYMBOLS 1,7 ... Display panel with a touch detection function, 2, 2B ... Pixel substrate, 3, 3B ... Opposite substrate, 6, 6B ... Liquid crystal layer, 10 ... Display device with a touch detection function, 11 ... Control part, 12 ... Gate driver , 13 ... Source driver, 14 ... Selection switch section, 15 ... Drive signal generation section, 16, 18 ... Drive electrode driver, 17 ... Switch group, 20 ... Liquid crystal display device, 21 ... TFT substrate, 22 ... Pixel electrode, 23 ... Insulating layer, 30 ... Touch detection device, 31 ... Glass substrate, 32 ... Color filter, 35 ... Polarizing plate, 40 ... Touch detection unit, 42 ... LPF unit, 43 ... A / D conversion unit, 44 ... Signal processing unit, 45 ... coordinate extraction unit, 51, 71 ... scanning control unit, 52, 52B ... touch detection scanning unit, 53, 530, 530B, 73, 730 ... driving unit, 54 ... logical product circuit, 55 ... invar 56, 57 ... buffer, 61 ... high level voltage generator, 62 ... low level voltage generator, 63, 64, 65 ... buffer, 66 ... switching circuit, B, B1-B20 ... drive electrode block, COML ... drive Electrode, EXVCOM ... Vcom control signal, GCL ... Scanning signal line, LC ... Liquid crystal element, Out ... Output signal, Pix ... Pixel, PW ... Writing period, Spix ... Sub pixel, Scan ... Display scan, Scant ... Touch detection scan, SGL ... Pixel signal line, St ... Scan signal, SWR, SRG, SWB, SW1, SW2 ... Switch, TDL ... Touch detection electrode, Tr ... TFT element, ts ... Sampling timing, Vcom ... Drive signal, VcomAC ... AC drive signal, VcomDC ... DC drive signal, VCOMSEL ... Vcom selection signal, Vdet ... touch detection signal, Vscan ... scan signal, Vsel, VselR, VselG, VselB ... switch H control signal, Vsig, Vpix, VpixR, VpixG, VpixB ... Pixel signal.

Claims (13)

One or more display elements;
One or more drive electrodes;
One or more touch detection electrodes;
A display panel with a touch detection function, comprising: a drive unit that selectively applies a DC drive signal or an AC drive signal to the drive electrode. The display element performs a display writing operation in a writing period,
The AC drive signal has a pulse waveform that transitions from a first voltage to a second voltage corresponding to a DC voltage level of the DC drive signal at a transition timing that does not belong to the writing period.
The drive unit performs the touch detection drive by applying the AC drive signal to the drive electrode in an enable period to which the transition timing belongs, and applying the DC drive signal in a period other than the enable period. The display panel with a touch detection function according to claim 1. The AC drive signal is a pulse waveform having the first voltage in a pulse period different from the writing period and having the second voltage in a period other than the pulse period,
The display panel with a touch detection function according to claim 2, wherein the transition timing corresponds to an end timing of the pulse period. The display panel with a touch detection function according to claim 3, wherein the enable period is a period different from the writing period. The display panel with a touch detection function according to claim 3, wherein the enable period is a period including the pulse period. The plurality of display elements are arranged in a matrix and perform display operation by line sequential scanning,
The display panel with a touch detection function according to claim 3, wherein the enable period corresponds to one or a plurality of continuous horizontal periods. A drive signal generator for generating the DC drive signal and the AC drive signal;
The drive signal generator is
A first voltage generator for generating the first voltage;
A second voltage generator for generating a voltage corresponding to a DC voltage level of the DC drive signal;
A buffer circuit that generates the second voltage based on an output voltage of the second voltage generator;
The display panel with a touch detection function according to claim 1, further comprising: a switching circuit that generates the AC drive signal by switching between the first voltage and the second voltage. A touch detection unit;
The plurality of drive electrodes are formed to extend in a predetermined direction,
The plurality of touch detection electrodes are formed in a layer different from the plurality of drive electrodes so as to extend in a direction intersecting with the extension direction of the drive electrodes,
The drive unit sequentially selects one or more of the plurality of drive electrodes as a drive target electrode, performs the touch detection drive on the drive target electrode, and applies to the drive electrodes other than the drive target electrode Applying the DC drive signal to
The display panel with a touch detection function according to claim 1, wherein the touch detection unit detects a touch based on an output signal from the touch detection electrode. The display element is
A liquid crystal layer;
The touch detection function according to claim 1, further comprising: a pixel electrode formed between the liquid crystal layer and the drive electrode, or a pixel electrode disposed so as to face the liquid crystal layer with the drive electrode interposed therebetween. Display panel. The display element is
A liquid crystal layer;
The display panel with a touch detection function according to claim 1, comprising: a pixel electrode disposed so as to face the drive electrode with the liquid crystal layer interposed therebetween. Drive display of one or more display elements;
A method for driving a display panel with a touch detection function, wherein a DC drive signal or an AC drive signal is selectively applied to one or a plurality of drive electrodes. A display driver for driving one or more display elements;
A touch detection drive unit that selectively applies a DC drive signal or an AC drive signal to one or a plurality of drive electrodes. A display panel with a touch detection function;
A control unit that performs operation control using the display panel with a touch detection function,
The display panel with a touch detection function is:
One or more display elements;
One or more drive electrodes;
One or more touch detection electrodes;
An electronic device comprising: a drive unit that selectively applies a DC drive signal or an AC drive signal to the drive electrode.

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