Display unit with touch panel, and driving method therefor

Abstract

To keep a sufficient report rate even when a display unit with an in-cell type touch panel is driven in a variable low-frame rate manner.SOLUTION: In an idle period, touch detection processing is performed at predetermined time intervals until a vertical synchronization signal Vsync is input. If the point of time when the vertical synchronization signal Vsync is input in the idle period is after the point of time which is a first predetermined time after the most recent point of time when sensor data corresponding to a plurality of sensor electrodes are all acquired through the touch detection processing, touch detection processing is performed at timing right after the end of the idle period in addition to predetermined timing in a display update period appearing right after the idle period.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The following disclosure relates to a display device, and more particularly to a display device including an in-cell touch panel and a driving method thereof. [Background technology]

[0002] Touch panels have traditionally been used as input devices for operating computer systems and the like. For example, in capacitive touch panels, the position of an object to be detected, such as an operator's finger or a touch pen, is detected based on changes in capacitance. An increasing number of liquid crystal display devices are also equipped with such touch panels.

[0003] There are several types of touch panels, but in recent years, in-cell touch panels have become mainstream on the market. In-cell touch panels are touch panels in which sensor electrodes are provided inside the two glass substrates that make up the display panel. In-cell touch panels use, for example, multiple rectangular sensor electrodes arranged in a matrix, and detect the touch position using a self-capacitance method. The multiple sensor electrodes are shared with a common electrode, which is an electrode used to display images. In other words, one electrode is used both as a sensor electrode for detecting the touch position and as a common electrode for displaying images. This configuration enables devices to be made thinner and lighter.

[0004] FIG. 23 is a diagram illustrating the principle of touch position detection in an in-cell touch panel. A capacitance C1 is formed between a sensor electrode 90 and a reference potential. In this state, when an operator's finger approaches the surface of the display panel, a capacitance C2 is formed between the sensor electrode 90 and the operator's finger. That is, when the sensor electrode 90 is touched, the capacitance increases. The touch position is detected based on this change in capacitance. More specifically, when acquiring sensor data for identifying the touch position, a drive signal, which is an AC signal, is applied to the sensor electrode. At this time, for example, sensor data corresponding to a change in current flowing through a sensing line connected to the sensor electrode is acquired as data representing the capacitance change at the sensor electrode. The touch position is then identified based on multiple sensor data corresponding to each of the multiple sensor electrodes. Note that hereinafter, the process of applying a drive signal to the sensor electrode and acquiring sensor data for identifying the touch position is referred to as a "touch detection process." For convenience, acquiring all of the multiple sensor data corresponding to each of the multiple sensor electrodes is referred to as "complete touch detection."

[0005] In a liquid crystal display device with an in-cell touch panel, as described above, one electrode is used both as a sensor electrode for detecting a touch position and as a common electrode for displaying an image. Therefore, a period for writing a video signal to a liquid crystal capacitor for image display (hereinafter referred to as a "video signal writing period") and a period for performing touch detection processing (hereinafter referred to as a "touch detection period") must be time-shared. Therefore, within one frame period, a video signal writing period 91 and a touch detection period 92 are repeated, for example, as shown in FIG. 24. In the example shown in FIG. 24, vertical scanning (sequential scanning of gate bus lines in a display unit one by one) is temporarily stopped every time a video signal is written to a liquid crystal capacitor corresponding to a certain number of gate bus lines (scanning signal lines) within one frame period. Touch detection processing is performed during this vertical scanning stop period. After complete touch detection, for example, a process for determining the coordinates of the touch position based on the plurality of sensor data is performed within the liquid crystal display device, and the coordinate data (data indicating the touch position) obtained by this process is transmitted to a host. 24, coordinate data is transmitted to the host (hereinafter simply referred to as a "report" for convenience) twice during one frame period. Therefore, if the frame rate for image display is 60 Hz, the report rate is 120 Hz.

[0006] During the video signal write period 91, as shown in FIG. 25, the potential VCOM of the sensor electrode is maintained at a constant level. In this state, the gate bus lines are sequentially selected one by one. During each horizontal scanning period within the video signal write period 91, the source potential (the potential of the video signal line) changes according to the target display image. Through the above operation, during the video signal write period 91, a video signal according to the target display image is written to the liquid crystal capacitance corresponding to the selected gate bus line. During the touch detection period 92, as shown in FIG. 25, an AC drive signal is applied to the sensor electrode. That is, during the touch detection period 92, the potential VCOM of the sensor electrode fluctuates. At this time, for example, a change in capacitance at the sensor electrode is detected based on a change in current flowing through a sensing line connected to the sensor electrode. Then, based on the change in capacitance at each portion of all the sensor electrodes (in other words, based on the above-mentioned multiple sensor data), it is possible to determine whether a touch has occurred and, if so, to determine the touch position.

[0007] In recent years, the adoption of "low frame rate drive," which provides pause periods during which the display image is not updated (refreshed), has been increasing in order to reduce the power consumption of display devices. In low frame rate drive, display update periods during which the display image is updated and pause periods during which the display image is not updated typically alternate. The length of the pause periods is usually an integer multiple of the length of the display update periods. When normal drive is performed at a frame rate of 120 Hz, the display image is updated based on input frame data every 8.33 milliseconds, as shown in FIG. 26 . In contrast, when low frame rate drive is performed, an 8.33 millisecond pause period appears after an 8.33 millisecond display update period, as shown in FIG. 27 . In this example, the frame rate is 60 Hz.

[0008] Regarding low frame rate driving, a driving method that changes the frame rate by varying the length of a pause period (hereinafter referred to as "variable low frame rate driving") is sometimes adopted. For example, variable low frame rate driving is adopted when input frame data is transferred irregularly from a host to a display device. FIG. 28 is a diagram for explaining an example of variable low frame rate driving. In the example shown in FIG. 28, no pause period appears after the display update period labeled 941, a 5-millisecond pause period appears after the display update period labeled 942, a 10-millisecond pause period appears after the display update period labeled 943, and a 3-millisecond pause period appears after the display update period labeled 944. In this example, the frame rate changes as indicated by the dotted line labeled 95.

[0009] Next, an example of a report rate will be described. When normal driving is performed with a frame rate of 120 Hz, a report is generated every 8.33 millisecond display update period, as shown in FIG. 29. In this case, the report rate is 120 Hz. Note that with respect to each drawing, the shaded areas such as the portion marked with reference numeral 961 in FIG. 29 represent video signal write periods, the shaded areas such as the portion marked with reference numeral 962 in FIG. 29 represent touch detection periods, and the shaded areas such as the portion marked with reference numeral 963 in FIG. 29 represent vertical blanking periods. When low frame rate driving is performed, in which an 8.33 millisecond pause period is provided every 8.33 millisecond display update period, a report is generated after the end of the 8.33 millisecond display update period and after the end of the 8.33 millisecond pause period, as shown in FIG. 30. In this case, the report rate is 120 Hz.

[0010] An example of variable low frame rate driving is shown below. It is assumed here that touch detection processing is performed during idle periods at the same timing as display update periods. In the example shown in FIG. 31, the idle period is 20 milliseconds long. In this example, two reports are performed during a 28.33-millisecond period. Therefore, the report rate during the period indicated by the arrow marked with reference symbol T901 is 70.6 Hz. In the example shown in FIG. 32, the idle period is 8 milliseconds long. In this example, a vertical synchronization signal is input during touch detection processing during the idle period, causing an abnormality in the touch detection processing (see the portion marked with reference symbol 97). In other words, no report is made on the results of touch detection processing during the idle period. Therefore, only one report is made during the period indicated by the arrow marked with reference symbol T902 (16.33 milliseconds), resulting in a report rate of 61.2 Hz during this period. In the example shown in FIG. 33, the idle period is 5 milliseconds long. In this example, a vertical synchronization signal is input before touch detection processing begins during the idle period. This allows the idle period to transition to the display update period without performing touch detection processing. Therefore, since a report is made only once during the period (13.33 milliseconds) indicated by the arrow marked with symbol T903, the report rate during that period is 75.0 Hz.

[0011] When variable low frame rate driving is performed, the report rate can drop significantly depending on the length of the idle period. Therefore, U.S. Pat. No. 11,209,932 proposes a method of repeating touch detection processing at predetermined time intervals during the idle period until a vertical synchronization signal is input to prevent the report rate from dropping. Furthermore, Japanese Patent Application Laid-Open No. 2018-060319 proposes a method of performing touch detection processing even during the extended vertical front porch period during low frame rate driving. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] U.S. Patent No. 11,209,932 [Patent Document 2] Japanese Patent Application Publication No. 2018-060319 Summary of the Invention [Problem to be solved by the invention]

[0013] However, according to the technique disclosed in U.S. Pat. No. 11,209,932, if a vertical synchronization signal is input during touch detection processing, for example, during a pause period, the coordinate data being processed is discarded (i.e., a report based on the coordinate data being processed is not performed), and the period between the previous report and the next report becomes longer. As a result, a sufficient report rate cannot be obtained. Furthermore, the technique disclosed in Japanese Patent Laid-Open No. 2018-060319 does not take variable low frame rate driving into consideration.

[0014] Therefore, the following disclosure aims to make it possible to maintain a sufficient report rate even when variable low frame rate driving is performed in a display device equipped with an in-cell touch panel. [Means for solving the problem]

[0015] (1) A display device according to some embodiments of the present invention is a display device including a touch panel including a plurality of sensor electrodes provided for detecting a touch position, a plurality of video signal lines for transmitting video signals; a plurality of scanning signal lines intersecting the plurality of video signal lines; a plurality of pixel formation portions, each including a capacitance, provided at each intersection of the plurality of video signal lines and the plurality of scanning signal lines; a video signal line drive circuit that applies the video signals to the plurality of video signal lines; a scanning signal line driving circuit that selectively drives the plurality of scanning signal lines; a touch detection circuit that performs touch detection processing by applying drive signals to the plurality of sensor electrodes to acquire sensor data for identifying a touch position; a timing control circuit that controls operations of the video signal line drive circuit, the scanning signal line drive circuit, and the touch detection circuit; Equipped with the timing control circuit is configured to be able to control operations of the video signal line drive circuit, the scanning signal line drive circuit, and the touch detection circuit so that a display update period in which a display image is updated by writing the video signal to the capacitor included in each of the plurality of pixel formation portions and a pause period of any length and variable length in which the display image is not updated are generated; When a vertical synchronization signal is input from an external device during the idle period, the idle period transitions to the display update period, the timing control circuit controls an operation of the touch detection circuit so that the touch detection process is performed at least at a predetermined timing during the display update period, and so that the touch detection process is performed at a predetermined time interval during the pause period until the vertical synchronization signal is input from outside; If the point at which the vertical synchronization signal is input from outside during the idle period is later than the point at which a first predetermined time has elapsed since the most recent point at which acquisition of all of the sensor data corresponding to each of the plurality of sensor electrodes was completed by the touch detection process, the timing control circuit controls the operation of the touch detection circuit so that the touch detection process is performed at the timing immediately after the end of the idle period in addition to the predetermined timing during the display update period that appears immediately after the idle period.

[0016] (2) Furthermore, a display device according to some embodiments of the present invention includes the configuration of (1) above, All of the sensor data corresponding to each of the plurality of sensor electrodes is acquired in one touch detection period during which the touch detection process is performed.

[0017] (3) Furthermore, a display device according to some embodiments of the present invention includes the configuration of (1) above, all of the sensor data corresponding to each of the plurality of sensor electrodes are acquired during a plurality of touch detection periods during which the touch detection process is performed; If the point at which the vertical synchronization signal is input from outside during the idle period is later than the point at which the first predetermined time has elapsed since the most recent point at which acquisition of all of the sensor data corresponding to each of the plurality of sensor electrodes was completed by the touch detection process, the timing control circuit controls the operation of the touch detection circuit so that the touch detection process is further performed at the timing of a flyback period that is provided between the touch detection period and a video signal write period in which the video signal is written to the capacitor.

[0018] (4) In addition to the configuration of (1), a display device according to some embodiments of the present invention includes a sensor data storage unit that stores the sensor data, and a coordinate calculation unit that calculates coordinates representing a touch position based on all of the sensor data corresponding to each of the plurality of sensor electrodes, the sensor data acquired by the touch detection process is stored in the sensor data storage unit; When the vertical synchronization signal is input from outside while the touch detection process is being performed during the pause period, the timing control circuit controls the operation of the touch detection circuit so that the touch detection process is interrupted and deletes the sensor data stored in the sensor data holding unit.

[0019] (5) Furthermore, a display device according to some embodiments of the present invention includes the configuration of (1) above, If the vertical synchronization signal is not input from the outside during the display update period until a second predetermined time has elapsed from the time when the process of writing the video signal to the capacitor for all of the plurality of pixel formation portions is completed, a transition from the display update period to the pause period occurs.

[0020] (6) Furthermore, a display device according to some embodiments of the present invention includes any one of the configurations (1) to (5) above, If complete touch detection is defined as obtaining all of the sensor data corresponding to each of the plurality of sensor electrodes through the touch detection process, and the frequency at which complete touch detection is performed is defined as a touch rate, the first predetermined time is set so that the touch rate during the period from the end of the last complete touch detection before the start of the first display update period after the transition from the pause period to the display update period to the end of the first display update period after the transition satisfies a target lower limit value.

[0021] (7) Furthermore, a display device according to some embodiments of the present invention includes the configuration of (6) above, The target lower limit is 100 Hz.

[0022] (8) Furthermore, a display device according to some embodiments of the present invention is a display device including a touch panel including a plurality of sensor electrodes provided for detecting a touch position, a plurality of video signal lines for transmitting video signals; a plurality of scanning signal lines intersecting the plurality of video signal lines; a plurality of pixel formation portions, each including a capacitance, provided at each intersection of the plurality of video signal lines and the plurality of scanning signal lines; a video signal line drive circuit that applies the video signals to the plurality of video signal lines; a scanning signal line driving circuit that selectively drives the plurality of scanning signal lines; a touch detection circuit that performs touch detection processing by applying drive signals to the plurality of sensor electrodes to acquire sensor data for identifying a touch position; a timing control circuit that controls operations of the video signal line drive circuit, the scanning signal line drive circuit, and the touch detection circuit; Equipped with the timing control circuit is configured to be able to control operations of the video signal line drive circuit, the scanning signal line drive circuit, and the touch detection circuit so that a display update period in which a display image is updated by writing the video signal to the capacitor included in each of the plurality of pixel formation portions and a pause period of any length and variable length in which the display image is not updated are generated; When a vertical synchronization signal is input from an external device during the idle period, the idle period transitions to the display update period, the timing control circuit controls an operation of the touch detection circuit so that the touch detection process is performed at least at a predetermined timing during the display update period, and so that the touch detection process is performed at a predetermined time interval during the pause period until the vertical synchronization signal is input from outside; all of the sensor data corresponding to each of the plurality of sensor electrodes is acquired during P touch detection periods in which the touch detection process is performed, where P is an integer equal to or greater than 2; If complete touch detection is defined as obtaining all of the sensor data corresponding to each of the plurality of sensor electrodes through the touch detection process, then when the vertical synchronization signal is input from outside while the touch detection process is being performed during the idle period and when the vertical synchronization signal is input from outside when the number of times the touch detection process has been performed since the end of the complete touch detection performed immediately before during the idle period is one or more and (P-1) or less, the timing control circuit controls the operation of the touch detection circuit so that the touch detection process is performed not only at the predetermined timing during the display update period that appears immediately after the idle period but also at the timing immediately after the end of the idle period and at the timing of a retrace period that is provided between the touch detection period and a video signal write period in which the video signal is written to the capacitor.

[0023] (9) Furthermore, a driving method according to some embodiments of the present invention is a driving method for a display device including a touch panel including a plurality of sensor electrodes provided for detecting a touch position, the driving method comprising: The display device includes: a plurality of video signal lines for transmitting video signals; a plurality of scanning signal lines intersecting the plurality of video signal lines; a plurality of pixel formation portions, each including a capacitance, provided at each intersection of the plurality of video signal lines and the plurality of scanning signal lines; a video signal line drive circuit that applies the video signals to the plurality of video signal lines; a scanning signal line driving circuit that selectively drives the plurality of scanning signal lines; a touch detection circuit that performs touch detection processing by applying drive signals to the plurality of sensor electrodes to acquire sensor data for identifying a touch position; a timing control circuit that controls operations of the video signal line drive circuit, the scanning signal line drive circuit, and the touch detection circuit; Equipped with The driving method includes: a display updating step in which the timing control circuit controls operations of the video signal line driving circuit and the scanning signal line driving circuit so that a display image is updated by performing a video signal writing process in which the video signal is written into the capacitor included in each of the plurality of pixel formation portions; a pause step in which the timing control circuit controls the operations of the video signal line drive circuit and the scanning signal line drive circuit so that the video signal writing process is paused throughout a pause period of any length and variable length; Including, In the display update step, the timing control circuit controls the operation of the touch detection circuit so that the touch detection process is performed at least at a predetermined timing; In the pause step, the timing control circuit controls the operation of the touch detection circuit so that the touch detection process is performed at predetermined time intervals during the pause period until a vertical synchronization signal is input from outside; If the point at which the vertical synchronization signal is input from outside during the idle period is later than the point at which a first predetermined time has elapsed since the most recent point at which acquisition of all of the sensor data corresponding to each of the plurality of sensor electrodes was completed by the touch detection process, then in the display update step that is performed next, the timing control circuit controls the operation of the touch detection circuit so that the touch detection process is performed at the timing immediately after the end of the idle period in addition to the predetermined timing.

[0024] (10) Furthermore, a driving method according to some embodiments of the present invention is a driving method for a display device including a touch panel including a plurality of sensor electrodes provided for detecting a touch position, the driving method comprising: The display device includes: a plurality of video signal lines for transmitting video signals; a plurality of scanning signal lines intersecting the plurality of video signal lines; a plurality of pixel formation portions, each including a capacitance, provided at each intersection of the plurality of video signal lines and the plurality of scanning signal lines; a video signal line drive circuit that applies the video signals to the plurality of video signal lines; a scanning signal line driving circuit that selectively drives the plurality of scanning signal lines; a touch detection circuit that performs touch detection processing by applying drive signals to the plurality of sensor electrodes to acquire sensor data for identifying a touch position; a timing control circuit that controls operations of the video signal line drive circuit, the scanning signal line drive circuit, and the touch detection circuit; Equipped with The driving method includes: a display updating step in which the timing control circuit controls operations of the video signal line driving circuit and the scanning signal line driving circuit so that a display image is updated by performing a video signal writing process in which the video signal is written into the capacitor included in each of the plurality of pixel formation portions; a pause step in which the timing control circuit controls the operations of the video signal line drive circuit and the scanning signal line drive circuit so that the video signal writing process is paused throughout a pause period of any length and variable length; Including, In the display update step, the timing control circuit controls the operation of the touch detection circuit so that the touch detection process is performed at least at a predetermined timing; In the pause step, the timing control circuit controls the operation of the touch detection circuit so that the touch detection process is performed at predetermined time intervals during the pause period until a vertical synchronization signal is input from outside; all of the sensor data corresponding to each of the plurality of sensor electrodes is acquired during P touch detection periods in which the touch detection process is performed, where P is an integer equal to or greater than 2; If complete touch detection is defined as obtaining all of the sensor data corresponding to each of the plurality of sensor electrodes through the touch detection process, then if the vertical synchronization signal is input from outside while the touch detection process is being performed during the idle period and if the vertical synchronization signal is input from outside when the number of times the touch detection process has been performed since the end of the complete touch detection performed immediately before during the idle period is one or more and (P-1) or less, in the display update step that is subsequently performed, the timing control circuit controls the operation of the touch detection circuit so that the touch detection process is performed not only at the predetermined timing but also at the timing immediately after the end of the idle period and at the timing of a retrace period that is provided between the touch detection period and a video signal write period in which the video signal is written to the capacitor. [Effects of the Invention]

[0025] In some embodiments of the display device, touch detection processing is repeated at predetermined time intervals during the idle period until a vertical synchronization signal is input from the outside. Furthermore, if a vertical synchronization signal is input from the outside after a first predetermined time has elapsed since the most recent time at which sensor data acquisition for all sensor electrodes was completed during the idle period, additional touch detection processing is performed during the display update period that appears immediately after the idle period. This prevents a decrease in the frequency of touch detection processing due to irregular changes in the length of the idle period, and enables data indicating the coordinates of the touch position to be transmitted to the outside with sufficient frequency. As described above, a display device with an in-cell touch panel can maintain a sufficient report rate even when variable low frame rate driving is performed. [Brief explanation of the drawings]

[0026] [Figure 1] FIG. 4 is a diagram illustrating the operation of the liquid crystal display device in the first embodiment of the present invention when the length of the idle period is 20 milliseconds. [Figure 2] FIG. 2 is a block diagram showing an overall configuration of the liquid crystal display device according to the first embodiment. [Figure 3] FIG. 3 is a block diagram showing a functional configuration of a drive unit in the first embodiment. [Figure 4] FIG. 2 is a diagram for explaining components for image display among components in a liquid crystal touch panel in the first embodiment. [Figure 5] FIG. 2 is a diagram for explaining components for detecting a touch position among components in a liquid crystal touch panel in the first embodiment. [Figure 6] FIG. 2 is a diagram for explaining the LVB method in the first embodiment. [Figure 7] 10 is a flowchart illustrating the flow of processing after writing to the final line in a display update period in the first embodiment. [Figure 8]10 is a flowchart illustrating the flow of processing after writing to the final line in a display update period in the first embodiment. [Figure 9] 10 is a flowchart illustrating the flow of processing after writing to the final line in a display update period in the first embodiment. [Figure 10] FIG. 10 is a diagram illustrating the operation of the liquid crystal display device in the first embodiment when the length of the pause period is 8 milliseconds. [Figure 11] FIG. 10 is a diagram illustrating the operation of the liquid crystal display device in the first embodiment when the length of the pause period is 9.5 milliseconds. [Figure 12] FIG. 10 is a diagram illustrating the operation of the liquid crystal display device in the first embodiment when the length of the pause period is 5 milliseconds. [Figure 13] FIG. 10 is a diagram illustrating the operation of the liquid crystal display device in the first embodiment when the length of the pause period is 1 millisecond. [Figure 14] FIG. 10 is a diagram illustrating the LHB method in the second embodiment of the present invention. [Figure 15] FIG. 10 is a diagram illustrating a display update period in the second embodiment. [Figure 16] 11 is a flowchart illustrating the flow of processing after writing to the final line in a display update period in the second embodiment. [Figure 17] FIG. 11 is a diagram illustrating the operation of the liquid crystal display device in the second embodiment when the length of the pause period is 20 milliseconds. [Figure 18] FIG. 11 is a diagram illustrating the operation of the liquid crystal display device in the second embodiment when the length of the pause period is 8 milliseconds. [Figure 19] FIG. 11 is a diagram illustrating the operation of the liquid crystal display device in the second embodiment when the length of the idle period is 10.1 milliseconds. [Figure 20] FIG. 11 is a diagram illustrating the operation of the liquid crystal display device in the second embodiment when the length of the pause period is 5 milliseconds. [Figure 21] FIG. 11 is a diagram illustrating the operation of the liquid crystal display device in the second embodiment when the length of the pause period is 1 millisecond. [Figure 22] 10 is a flowchart illustrating the flow of processing after writing to the final line in a display update period in a modification of the second embodiment. [Figure 23] 10A and 10B are diagrams illustrating the principle of detecting a touch position in an in-cell touch panel according to a conventional example. [Figure 24] FIG. 10 is a diagram illustrating one frame period in a liquid crystal display device having an in-cell touch panel in a conventional example. [Figure 25] FIG. 10 is a waveform diagram for explaining the potential of a sensor electrode in the conventional example. [Figure 26] FIG. 10 is a diagram for explaining normal driving in a conventional example. [Figure 27] FIG. 10 is a diagram for explaining an example of low frame rate driving in a conventional example. [Figure 28] 10A and 10B are diagrams illustrating an example of variable low frame rate driving in a conventional example. [Figure 29] FIG. 10 is a diagram illustrating a report rate when normal driving is performed in a conventional example. [Figure 30] 10A and 10B are diagrams illustrating a report rate when low frame rate driving is performed in a conventional example. [Figure 31] FIG. 10 is a diagram for explaining the report rate when variable low frame rate driving is performed in a conventional example (when the length of the pause period is 20 milliseconds). [Figure 32] FIG. 10 is a diagram for explaining the report rate when variable low frame rate driving is performed in a conventional example (when the length of the pause period is 8 milliseconds). [Figure 33] FIG. 10 is a diagram for explaining the report rate when variable low frame rate driving is performed in a conventional example (when the length of the pause period is 5 milliseconds). DETAILED DESCRIPTION OF THE INVENTION

[0027] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0028] <1. First embodiment> <1.1 Configuration of LCD> 2 is a block diagram showing the overall configuration of a liquid crystal display device 1 according to a first embodiment of the present invention. The liquid crystal display device 1 is composed of a liquid crystal touch panel 10 and a PCB (printed circuit board) 20 on which various ICs and the like are mounted. The liquid crystal display device 1 is also connected to an external host 30. The liquid crystal touch panel 10 is composed of two glass substrates facing each other, a TFT array substrate and a color filter substrate, and the PCB 20 is provided on the back surface of the liquid crystal touch panel 10, for example.

[0029] The LCD touch panel 10 has functions for image display and touch position detection. In the LCD touch panel 10, a driving unit 100 that drives components for image display and components for touch position detection is provided in an area outside an active area 190, which is the effective display area. As shown in FIG. 3, the driving unit 100 functionally includes a source driver (video signal line driving circuit) 110 that applies video signals to each source bus line (video signal line), and a touch detection circuit 120 that performs the above-mentioned touch detection process. As hardware, the driving unit 100 is composed of multiple ICs 102. Each IC 102 functions as a source driver 110 and a touch detection circuit 120.

[0030] The PCB 20 includes a timing controller (timing control circuit) 210, a level shifter IC 220, a sensor electrode potential control IC 230, and a coordinate calculation unit 240. The coordinate calculation unit 240 is realized by an MCU (Micro Controller Unit). The coordinate calculation unit 240 includes a sensor data holding unit 241 that stores sensor data DS sent from the touch detection circuit 120.

[0031] The timing controller 210 receives a vertical synchronization signal Vsync, a horizontal synchronization signal Hsync, and image data DAT sent from the host 30, and outputs a digital video signal DV, a source control signal SCTL that controls the operation of the source driver 110, a touch control signal TCTL that controls the operation of the touch detection circuit 120, a timing signal TS that is the source of a gate control signal GCTL that controls the operation of a gate driver described later, a sensor electrode potential control signal VCTL that controls the operation of the sensor electrode potential control IC 230, and an MCU control signal MCTL that controls the operation of the coordinate calculation unit 240. The source control signal SCTL includes a source start pulse signal, a source clock signal, a latch strobe signal, etc.

[0032] The level shifter IC220 generates and outputs a gate control signal GCTL by converting the voltage level (potential) of the timing signal TS provided by the timing controller 210. The gate control signal GCTL includes a gate start pulse signal, a gate clock signal, and the like. The sensor electrode potential control IC230 controls the potential VCOM of the sensor electrode (common electrode) based on the sensor electrode potential control signal VCTL provided by the timing controller 210. The potential VCOM of the sensor electrode is maintained at a constant level during periods other than the touch detection period, and fluctuates during the touch detection period (see FIG. 25). The coordinate calculation unit 240, under the control of the MCU control signal MCTL provided by the timing controller 210, calculates coordinates representing the touch position from the sensor data DS, which is a digital signal sent from the touch detection circuit 120, and transmits coordinate data PD indicating the coordinates to the host 30.

[0033] 4 is a diagram illustrating components for image display among the components in the liquid crystal touch panel 10. The liquid crystal touch panel 10 includes a display unit 101, a source driver (video signal line drive circuit) 110, and a gate driver (scanning signal line drive circuit) 130.

[0034] The display unit 101 displays an image under the control of a source driver 110 and a gate driver 130. The display unit 101 is provided with n (plurality of) source bus lines (video signal lines) SL and m (plurality of) gate bus lines (scanning signal lines) GL. Pixel formation portions 14 that form pixels are provided at each intersection of the n source bus lines SL and the m gate bus lines GL. That is, the display unit 101 includes n×m pixel formation portions 14 (however, only one pixel formation portion 14 is shown in FIG. 4). The n×m pixel formation portions 14 form a pixel matrix of n rows and m columns. Each pixel formation portion 14 includes a pixel TFT (pixel transistor) 140, which is a thin-film transistor having a gate terminal connected to a gate bus line GL passing through the corresponding intersection and a source terminal connected to a source bus line SL passing through the intersection, a pixel electrode 141 connected to the drain terminal of the pixel TFT 140, a sensor electrode (common electrode) 150 functioning as an electrode for touch position detection and an electrode for image display, an auxiliary capacitance electrode 145 provided in common to the n×m pixel formation portions 14, a liquid crystal capacitance 142 formed by the pixel electrode 141 and the sensor electrode 150, and an auxiliary capacitance 143 formed by the pixel electrode 141 and the auxiliary capacitance electrode 145. The liquid crystal capacitance 142 and the auxiliary capacitance 143 form a pixel capacitance 146. Note that a configuration without the auxiliary capacitance 143 (i.e., a configuration without the auxiliary capacitance electrode 145) may also be employed.

[0035] The pixel TFT 140 may be, for example, a thin-film transistor (oxide semiconductor TFT) using an oxide semiconductor in the semiconductor layer. More specifically, a TFT (hereinafter referred to as an "IGZO-TFT") having a channel layer formed of In-Ga-Zn-O (indium gallium zinc oxide), an oxide semiconductor primarily composed of indium (In), gallium (Ga), zinc (Zn), and oxygen (O), may be used as the pixel TFT 140. Because oxide semiconductors have high electron mobility, using an oxide semiconductor TFT such as an IGZO-TFT enables the pixel TFT 140 to be miniaturized, which is advantageous in terms of achieving high definition and a high aperture ratio. Furthermore, reduced leakage current is advantageous in terms of reducing power consumption. Note that TFTs other than oxide semiconductor TFTs may also be used as the pixel TFT 140. In this regard, for example, a thin-film transistor using low-temperature polysilicon in the semiconductor layer (LTPS-TFT) may also be used.

[0036] The source driver 110 applies a driving video signal to each source bus line SL based on the digital video signal DV and source control signal SCTL sent from the timing controller 210. At this time, the source driver 110 sequentially holds the digital video signal DV indicating the voltage to be applied to each source bus line SL at the timing when a pulse of the source clock signal is generated. Then, at the timing when a pulse of the latch strobe signal is generated, the held digital video signal DV is converted into an analog voltage. The converted analog voltage is applied simultaneously to all source bus lines SL as a driving video signal.

[0037] The gate driver 130 applies an active scanning signal to each gate bus line GL repeatedly, with one vertical scanning period as a cycle, based on the gate control signal GCTL output from the level shifter IC 220. That is, the gate driver 130 selectively drives the m gate bus lines GL. The gate driver 130 is formed directly on the TFT array substrate.

[0038] In this manner, video signals are applied to the source bus lines SL and scanning signals are applied to the gate bus lines GL, whereby an image based on the image data DAT sent from the host 30 is displayed on the display unit 101.

[0039] The liquid crystal display device 1 according to this embodiment performs the variable low frame rate driving described above. To achieve this, the timing controller 210 is configured to be able to control the operations of the source driver 110, the gate driver 130, and the touch detection circuit 120 so that a display update period (a period during which a display image is updated by writing a video signal to the liquid crystal capacitors 142 included in each of the n×m pixel formation portions 14) and a pause period (a period during which the display image is not updated) of any length and variable length appear.

[0040] 5 is a diagram illustrating the components for detecting a touch position among the components in the liquid crystal touch panel 10. As described above, the liquid crystal touch panel 10 in this embodiment is composed of two glass substrates facing each other, a TFT array substrate and a color filter substrate, and the components for detecting a touch position are provided on the TFT array substrate of the two glass substrates.

[0041] The liquid crystal touch panel 10 includes a plurality of rectangular sensor electrodes 150, a touch detection circuit 120, and a plurality of sensing lines SNL. One end of each sensing line SNL is connected to a contact portion 151 formed on the corresponding sensor electrode 150, and the other end of each sensing line SNL is connected to the touch detection circuit 120. In this embodiment, the plurality of sensor electrodes 150 are formed by dividing a conventional common electrode into a matrix as shown in FIG. 5. In this regard, as an example, a conventional common electrode is divided into 18 portions in the horizontal direction (the direction in which the gate bus lines GL extend) and into 32 portions in the vertical direction (the direction in which the source bus lines SL extend). In this case, 576 sensor electrodes 150 are formed in the liquid crystal touch panel 10. As described above, the plurality of sensor electrodes 150 function as electrodes for detecting a touch position and electrodes for displaying an image. As described above, the liquid crystal display device 1 according to this embodiment is a liquid crystal display device equipped with an in-cell touch panel, and touch position detection is performed by a self-capacitance method.

[0042] The operation of the touch detection circuit 120 is controlled based on a touch control signal TCTL sent from the timing controller 210. During periods other than the touch detection period, the touch detection circuit 120 maintains the potential VCOM of the sensor electrode 150 at a constant level. During the touch detection period, the touch detection circuit 120 varies the potential VCOM of the sensor electrode 150 and outputs, as sensor data DS, a digital signal obtained by AD converting an analog voltage corresponding to the magnitude of the current flowing through the sensing line SNL. Note that the touch detection circuit 120 is provided with one AFE (analog front end) for each of the multiple sensing lines SNL. The AFE is configured, for example, with an operational amplifier, an AD converter, etc. The provision of the AFE makes it possible to obtain suitable sensor data DS, for example, from which noise has been removed.

[0043] <1.2 Driving method> Next, a driving method in this embodiment will be described.

[0044] <1.2.1 Overview> As a time division driving method for providing a video signal write period and a touch detection period in a time division manner, there are an LHB (Long Horizontal Blanking) method in which a video signal write period and a touch detection period are each provided multiple times within one display update period, and an LVB (Long Vertical Blanking) method in which a video signal write period and a touch detection period are each provided only once within one display update period. In this embodiment, the LVB method is adopted, and a vertical blanking interval is provided each time one video signal write period of a desired length and one touch detection period of a desired length end, as shown in FIG. 6 . According to the LVB method, all of the sensor data DS corresponding to each of the plurality of sensor electrodes 150 is acquired during one touch detection period in which touch detection processing is performed.

[0045] Hereinafter, the first row of the pixel matrix (a set of pixel forming portions 14 including pixel TFTs 140 whose gate terminals are connected to the first gate bus line GL) will be referred to as the "first line," and the nth row of the pixel matrix (a set of pixel forming portions 14 including pixel TFTs 140 whose gate terminals are connected to the nth gate bus line GL) will be referred to as the "last line."

[0046] In this embodiment, if a vertical synchronization signal Vsync is input during a pause period after a predetermined time (hereinafter referred to as a "first predetermined time") has elapsed since the end of the previous complete touch detection, an additional touch detection process is performed immediately after the start of the display update period that appears immediately after the pause period (an additional touch detection period is provided). Furthermore, if a vertical synchronization signal Vsync is not input during the display update period until a predetermined time (hereinafter referred to as a "second predetermined time") has elapsed since the last line was written (a video signal was written to the liquid crystal capacitor 142 included in the pixel formation portion 14 that constitutes the last line), a transition from the display update period to a pause period occurs. Furthermore, similar to the method disclosed in U.S. Pat. No. 11,209,932, touch detection processes are repeated at predetermined time intervals during the pause period until a vertical synchronization signal Vsync is input. In this regard, if a vertical synchronization signal Vsync is not input during the pause period until a predetermined time (hereinafter referred to as a "third predetermined time") has elapsed since the end of the previous touch detection process, touch detection processes are initiated. In this embodiment, all of the plurality of sensor data DS corresponding to the plurality of sensor electrodes 150 are acquired in one touch detection period. That is, complete touch detection is achieved by the touch detection process performed in one touch detection period.

[0047] <1.2.2 Processing flow> The flow of processing after writing to the final line in a display update period will be described with reference to the flowcharts shown in FIGS.

[0048] After the final line has been written, it is determined whether or not a vertical synchronization signal Vsync has been input from the host 30 during the period from the time when the final line has been written (in other words, the time when the process of writing video signals to the liquid crystal capacitors 142 for all of the n×m pixel formation units 14 has ended) until the second predetermined time has elapsed (step S110). If the vertical synchronization signal Vsync has been input, the process proceeds to step S210 (see FIG. 8 ), and if the vertical synchronization signal Vsync has not been input, the process proceeds to step S120. Note that if the vertical synchronization signal Vsync has not been input, a transition from the display update period to a pause period is performed. In this way, if a vertical synchronization signal Vsync has not been input from the host 30 during the display update period during the period from the time when the process of writing video signals to the liquid crystal capacitors 142 for all of the n×m pixel formation units 14 has ended until the second predetermined time has elapsed.

[0049] In step S210, a write process (a process of writing a video signal to the liquid crystal capacitor 142) is performed line by line from the first line to the last line. This updates (refreshes) the display image for one screen. Thereafter, a touch detection process and a report of the results obtained from the touch detection process (transmission of coordinate data PD indicating the touch position to the host 30) are performed (step S220). After step S220 is completed, the process returns to step S110.

[0050] In step S120, it is determined whether or not a vertical synchronization signal Vsync has been input from the host 30 during the period from the end of the previous complete touch detection until the first predetermined time has elapsed. If a vertical synchronization signal Vsync has been input, the process proceeds to step S210 (see FIG. 8), and if a vertical synchronization signal Vsync has not been input, the process proceeds to step S130. If a vertical synchronization signal Vsync has been input, a transition from the pause period to the display update period is performed.

[0051] In step S130, it is determined whether or not a vertical synchronization signal Vsync has been input from the host 30 during the period from the end of the previous touch detection process (in this embodiment, the end of the previous complete touch detection) until the third predetermined time has elapsed. If a vertical synchronization signal Vsync has been input, the process proceeds to step S310 (see FIG. 9 ), and if a vertical synchronization signal Vsync has not been input, the process proceeds to step S140. If a vertical synchronization signal Vsync has been input, a transition from the pause period to a display update period is performed. Note that the third predetermined time is longer than the first predetermined time, and the third predetermined time is set to the time from the end of the previous touch detection process to the time when the next touch detection process should start.

[0052] The process moves from step S130 or step S160 (described later) to step S310 when a transition from a pause period to a display update period occurs. When display update periods are repeated without a pause period in between, a vertical blanking interval is provided immediately after the start of each display update period. In contrast, in step S310, touch detection processing and reporting of the results obtained in the touch detection processing are performed immediately after the start of the display update period. Thus, in step S310, an additional touch detection processing is performed, unlike in a normal display update period. After step S310 is completed, writing processing is performed line by line from the first line to the last line (step S320). This updates the display image for one screen. Thereafter, touch detection processing and reporting of the results obtained in the touch detection processing are performed (step S330). After step S330 is completed, the process returns to step S110.

[0053] As described above, if the time when the vertical synchronization signal Vsync is input from the host 30 during the idle period is later than the time when the first predetermined time has elapsed since the most recent time when acquisition of all of the sensor data DS corresponding to each of the multiple sensor electrodes 150 was completed by the touch detection process, the timing controller 210 controls the operation of the touch detection circuit 120 so that the touch detection process is performed immediately after the end of the idle period in addition to the timing (predetermined timing) after the writing process from the first line to the last line has been completed during the display update period that appears immediately after the idle period.

[0054] In step S140, while the idle period is continuing, touch detection processing is started. Thereafter, it is determined whether or not a vertical synchronization signal Vsync has been input from the host 30 before the touch detection processing ends (step S150). As a result, if a vertical synchronization signal Vsync has been input, the processing proceeds to step S160, and if a vertical synchronization signal Vsync has not been input, the processing proceeds to step S170. If a vertical synchronization signal Vsync has been input, a transition from the idle period to a display update period is made.

[0055] When the process moves from step S150 to step S160, incomplete sensor data DS has been accumulated in the sensor data holding unit 241 in the coordinate calculation unit 240. Therefore, in step S160, the incomplete sensor data DS is discarded (deleted) from the sensor data holding unit 241. In this way, if a vertical synchronization signal Vsync is input from the host 30 while the touch detection process is being performed in the idle period, the timing controller 210 controls the operation of the touch detection circuit 120 so that the touch detection process is interrupted, and deletes the sensor data DS stored in the sensor data holding unit 241. After step S160 ends, the process proceeds to step S310 described above (see FIG. 9).

[0056] When the process moves from step S150 to step S170, the complete sensor data DS (all of the sensor data DS corresponding to each of the plurality of sensor electrodes 150) has been accumulated in the sensor data holding unit 241. Therefore, in step S170, a report is made of the results obtained based on the complete sensor data DS. After step S170 is completed, the process returns to step S120.

[0057] <1.2.3 Specific examples> Hereinafter, how the liquid crystal display device 1 according to this embodiment is driven depending on the length of the pause period will be described. It is assumed that the length of one display update period is 8.33 milliseconds, the first predetermined time is set to 1.67 milliseconds, the second predetermined time is set to the time from when writing to the last line in a display update period is to be performed to when the next display update period is to be started, and the third predetermined time is set to the time from when the previous touch detection process ends to when the next touch detection process is to be started, as described above. Hereinafter, for convenience, the report rate during the period from the end of the last complete touch detection before the end of the pause period to the end of the display update period that appears immediately after the pause period will be referred to as the "post-pause report rate."

[0058] With reference to FIG. 1, the operation when the length of the idle period is 20 milliseconds will be described. The control signal INT is included in the MCU control signal MCTL (see FIG. 2) sent from the timing controller 210 to the coordinate calculation unit 240, and is a signal that instructs the coordinate calculation unit 240 to transmit coordinate data PD to the host 30. In this case, since no vertical synchronization signal Vsync is input from the host 30 within a second predetermined time from time t01 when writing to the last line is performed, a transition from the display update period to the idle period occurs. Note that, when the display update period transitions to the idle period, a report (sending coordinate data PD indicating the touch position to the host 30) is made based on the results obtained in the immediately preceding touch detection process (touch detection process performed during the period from time t01 to time t02). Since no vertical synchronization signal Vsync is input from the host 30 until time t03, when the third predetermined time has elapsed, from time t02 when the touch detection process ends, the touch detection process starts at time t03. Thereafter, since there is no input of a vertical synchronization signal Vsync from the host 30 by the end of the touch detection process, time t04, a report is made based on the results obtained in the touch detection process (the touch detection process performed during the period from time t03 to time t04). Furthermore, there is no input of a vertical synchronization signal Vsync from the host 30 by time t05, when a third predetermined time has elapsed since the end of the touch detection process, time t04, so the touch detection process is started at time t05. Thereafter, there is no input of a vertical synchronization signal Vsync from the host 30 by time t06, when the touch detection process ends, so a report is made based on the results obtained in the touch detection process (the touch detection process performed during the period from time t05 to time t06). Thereafter, a vertical synchronization signal Vsync is input from the host 30 by the end of the touch detection process, time t06, when the third predetermined time has elapsed (at time t07), thereby transitioning from the pause period to the display update period. At this time, since the vertical synchronization signal Vsync is not input from the host 30 between the end of the touch detection process at time t06 and the time when the first predetermined time has elapsed, the touch detection process is performed immediately after the start of the display update period (the period from time t07 to time t08), and further, a report is generated based on the results obtained from the touch detection process.Thereafter, the same operation as in a normal display update period is carried out.

[0059] As shown in the following equation (1), the post-pause report rate R in this case (the report rate during the period indicated by the arrow with symbol T100) is 171.4 Hz. Note that, according to a conventional method that does not perform additional touch detection processing, the post-pause report rate is 85.7 Hz. R = (1 / ((3.34 + 8.33) / 2)) × 1000 =171.4 (1)

[0060] With reference to FIG. 10, the operation when the idle period is 8 milliseconds will be described. In this case, after the transition from the display update period to the idle period, no vertical synchronization signal Vsync is input from the host 30 between time t11 when the touch detection process ends and time t02 when the third predetermined time has elapsed. Therefore, the touch detection process starts at time t12. Thereafter, the vertical synchronization signal Vsync is input from the host 30 before the touch detection process ends. Therefore, the incomplete sensor data DS (see the portion marked with reference numeral 41 in FIG. 10) accumulated in the sensor data holding unit 241 in the coordinate calculation unit 240 is discarded. Then, the idle period transitions to the display update period. At this time, the touch detection process is performed immediately after the start of the display update period (the period from time t13 to time t14), and further, a report based on the results of the touch detection process is generated. Thereafter, the same operation as in the normal display update period is performed.

[0061] As shown in the following equation (2), the post-pause report rate R in this case (the report rate during the period indicated by the arrow with symbol T101) is 122.5 Hz. Note that, according to a conventional method that does not perform additional touch detection processing, the post-pause report rate is 61.2 Hz. R=(1 / ((8+8.33) / 2))×1000 =122.5 (2)

[0062] With reference to FIG. 11 , the operation when the idle period is 9.5 milliseconds will be described. In this case, after the transition from the display update period to the idle period, there is no input of a vertical synchronization signal Vsync from the host 30 between time t21, when the touch detection process ends, and time t22, when the third predetermined time has elapsed. Therefore, the touch detection process is started at time t22. Thereafter, there is no input of a vertical synchronization signal Vsync from the host 30 until time t23, when the touch detection process ends. Therefore, a report is generated based on the results of the touch detection process (the touch detection process performed during the period from time t22 to time t23). The transition from the idle period to the display update period is performed by inputting a vertical synchronization signal Vsync from the host 30 between time t23, when the touch detection process ends, and time t24, when the first predetermined time has elapsed. At this time, the touch detection process is not performed immediately after the start of the display update period. Then, from time t24 onward, the same operation as in a normal display update period is performed.

[0063] As shown in the following equation (3), the post-pause report rate R in this case (the report rate during the period indicated by the arrow with reference symbol T102) is 105.3 Hz. R = (1 / ((1.17 + 8.33) / 1)) × 1000 =105.3 (3)

[0064] With reference to FIG. 12, the operation when the idle period is 5 milliseconds will be described. In this case, after the display update period transitions to the idle period, a vertical synchronization signal Vsync is input from the host 30 between the end time t31 of the touch detection process and the third predetermined time (at time t32). As a result, the idle period transitions to the display update period at time t32 without the touch detection process being performed during the idle period. At this time, since the vertical synchronization signal Vsync is not input from the host 30 between the end time t31 of the touch detection process and the first predetermined time, the touch detection process is performed immediately after the start of the display update period (the period from time t32 to time t33), and further, a report based on the results of the touch detection process is generated. Thereafter, the same operation as in a normal display update period is performed.

[0065] As shown in the following equation (4), the post-pause report rate R in this case (the report rate during the period indicated by the arrow with symbol T103) is 150.0 Hz. Note that, according to a conventional method that does not perform additional touch detection processing, the post-pause report rate is 75.0 Hz. R=(1 / ((5+8.33) / 2))×1000 =150.0 (4)

[0066] With reference to FIG. 13, the operation when the idle period is 1 millisecond will be described. In this case, since no vertical synchronization signal Vsync is input from the host 30 within the second predetermined time from time t41 when writing to the last line is performed, a transition from the display update period to the idle period occurs. Note that, when the display update period transitions to the idle period, a report is generated based on the results of the immediately preceding touch detection process (the touch detection process performed during the period from time t41 to time t42). A vertical synchronization signal Vsync is input from the host 30 between time t42 when the touch detection process ends and time t43 when the first predetermined time has elapsed. As a result, the idle period transitions to the display update period at time t43 without any touch detection process being performed during the idle period. At this time, no touch detection process is performed immediately after the start of the display update period. Then, from time t44 onward, the same operation as during a normal display update period occurs.

[0067] As shown in the following equation (5), the post-pause report rate R in this case (the report rate during the period indicated by the arrow with reference symbol T104) is 107.2 Hz. R = (1 / ((1+8.33) / 1)) × 1000 =107.2 (5)

[0068] In the above example, the post-pause report rate R becomes the lowest when the vertical synchronization signal Vsync is input from the host 30 immediately before 1.67 milliseconds (first predetermined time) has elapsed since the end of the previous touch detection process (the end of the previous complete touch detection). In this case, the post-pause report rate R is 100.0 Hz, as shown in the following equation (6). Therefore, a report rate of 100.0 Hz or higher is guaranteed. R = (1 / ((1.67 + 8.33) / 1)) × 1000 =100.0 (6)

[0069] If the frequency at which complete touch detection is performed is defined as the touch rate, it is preferable to set the first predetermined time so that the touch rate during the period from the end of the last complete touch detection before the start of the first display update period after the transition from a pause period to a display update period to the end of the first display update period after the transition satisfies a target lower limit. In this regard, the post-pause report rate R corresponds to the touch rate, and the target lower limit is set to, for example, 100 Hz.

[0070] <1.3 Effects> According to this embodiment, in the liquid crystal display device 1 equipped with an in-cell touch panel, touch detection processing is repeated at predetermined time intervals during a pause period until a vertical synchronization signal Vsync is input from the host 30. Furthermore, if a vertical synchronization signal Vsync is input from the host 30 after a first predetermined time has elapsed since the most recent complete touch detection during the pause period, touch detection processing is performed immediately after the end of the pause period (in other words, immediately after the start of the display update period that appears immediately after the pause period) in addition to a predetermined timing (specifically, the timing after the writing processing from the first line to the last line has been completed) during the display update period that appears immediately after the pause period. This prevents a decrease in the frequency of execution of touch detection processing due to irregular changes in the length of the pause period, and enables coordinate data PD indicating the touch position to be transmitted to the host 30 with sufficient frequency. As described above, according to this embodiment, a sufficient report rate can be maintained even when variable low frame rate driving is performed in the liquid crystal display device 1 equipped with an in-cell touch panel.

[0071] 2. Second embodiment <2.1 Configuration> The overall configuration of the liquid crystal display device 1 according to the second embodiment of the present invention is the same as that of the first embodiment (see FIG. 2). The functional configuration of the drive unit 100 (see FIG. 3), the configuration for image display (see FIG. 4), and the configuration for touch position detection (see FIG. 5) are also the same as those of the first embodiment.

[0072] <2.2 Driving method> Next, a driving method in this embodiment will be described.

[0073] <2.2.1 Overview> In this embodiment, variable low frame rate driving is also performed. Therefore, in this embodiment, time-division driving is also performed, in which a video signal write period and a touch detection period are provided in a time-division manner. Regarding the time-division driving method, the LVB method (see FIG. 6) was adopted in the first embodiment, but the LHB method is adopted in this embodiment. When the LHB method is adopted, a video signal write period, a touch detection period, and a long horizontal retrace period (a retrace period longer than the horizontal retrace period provided between a period in which writing to a certain line is performed and a period in which writing to the next line is performed) are each provided multiple times within one display update period, as shown in FIG. 14, for example. Note that with respect to each drawing, a shaded portion such as the portion labeled with reference numeral 63 in FIG. 14 represents a long horizontal retrace period, a shaded portion such as the portion labeled with reference numeral 61 in FIG. 14 represents a video signal write period as described above, and a shaded portion such as the portion labeled with reference numeral 62 in FIG. 14 represents a touch detection period as described above.

[0074] In the LHB method, all of the plurality of sensor data DS corresponding to each of the plurality of sensor electrodes 150 is acquired by touch detection processing performed over multiple touch detection periods. That is, in one touch detection period, only sensor data DS for some of the sensor electrodes 150 is acquired. In this embodiment, all of the plurality of sensor data DS corresponding to each of the plurality of sensor electrodes 150 is acquired by touch detection processing performed over four touch detection periods (for example, touch detection periods denoted by reference numerals 64 to 67 in FIG. 14). That is, complete touch detection is realized by touch detection processing performed over four touch detection periods. Therefore, a report is made every time four touch detection periods are completed, except when incomplete sensor data DS is discarded.

[0075] In this embodiment, as shown in part A of Fig. 15 , a normal display update period includes four repeated periods each consisting of a long horizontal blanking interval, a video signal write interval, and a touch detection interval. Therefore, one display update period includes four touch detection periods (touch detection periods indicated by reference numerals 71 to 74). In contrast, when a vertical synchronization signal Vsync is input after a first predetermined time has elapsed since the end of the previous complete touch detection during a pause period, the long horizontal blanking interval in the normal display update period is used as the touch detection period during the pause period, as shown in part B of Fig. 15 . That is, the display update period in this case includes the original four touch detection periods (touch detection periods indicated by reference numerals 81 to 84) and additional four touch detection periods (touch detection periods indicated by reference numerals 81a to 84a). Hereinafter, driving the liquid crystal display device 1 so that the configuration of the display update period is as shown in part A of Fig. 15 will be referred to as "first drive," and driving the liquid crystal display device 1 so that the configuration of the display update period is as shown in part B of Fig. 15 will be referred to as "second drive." As described above, complete touch detection is achieved by the touch detection process performed in four touch detection periods, so that only one report is made in the display update period when the first drive is performed, and two reports are made in the display update period when the second drive is performed.

[0076] Furthermore, similar to the first embodiment, if a vertical synchronization signal Vsync is not input during a display update period until a second predetermined time has elapsed since the last line was written during that period, a transition from the display update period to a pause period is performed. Furthermore, similar to the first embodiment, touch detection processing is repeated at predetermined time intervals during the pause period until a vertical synchronization signal Vsync is input. In this regard, if a vertical synchronization signal Vsync is not input during a pause period until a third predetermined time has elapsed since the end of the previous touch detection processing, touch detection processing is started.

[0077] <2.2.2 Processing flow> The flow of processing after writing to the final line in a display update period will be described with reference to the flowchart shown in Fig. 16. Note that in this embodiment, the length of one display update period is also assumed to be 8.33 milliseconds.

[0078] After writing to the final line, first, a counter value (hereinafter referred to as "count value") Cnt that counts the number of occurrences of touch detection periods is set to 0 (step S410). Then, it is determined whether or not a vertical synchronization signal Vsync has been input from the host 30 until a second predetermined time, similar to that in the first embodiment, has elapsed since writing to the final line (step S420). As a result, if a vertical synchronization signal Vsync has been input, the process proceeds to step S510, and if a vertical synchronization signal Vsync has not been input, the process proceeds to step S430. Note that if a vertical synchronization signal Vsync has not been input, a transition from the display update period to a pause period occurs.

[0079] In step S510, a first drive is performed. By performing the first drive, one screen's worth of the displayed image is updated, and a report is made of the results obtained based on the complete sensor data DS (all of the sensor data DS corresponding to each of the plurality of sensor electrodes 150). After step S510 is completed, the process returns to step S410.

[0080] In step S430, it is determined whether or not a vertical synchronization signal Vsync has been input from the host 30 until the first predetermined time, similar to that in the first embodiment, has elapsed since the end of the previous complete touch detection. If a vertical synchronization signal Vsync has been input, the process proceeds to step S510 described above, and if a vertical synchronization signal Vsync has not been input, the process proceeds to step S440.

[0081] In step S440, it is determined whether or not a vertical synchronization signal Vsync has been input from the host 30 during the period from the end of the previous touch detection process until a third predetermined time (the time from the end of the previous touch detection process to the start of the next touch detection process) has elapsed. If a vertical synchronization signal Vsync has been input, the process proceeds to step S610; if a vertical synchronization signal Vsync has not been input, the process proceeds to step S450. If a vertical synchronization signal Vsync has been input, a transition from the pause period to a display update period is performed.

[0082] In step S450, touch detection processing is started while the idle period is continuing. Thereafter, it is determined whether or not a vertical synchronization signal Vsync has been input from the host 30 before the touch detection processing ends (step S460). As a result, if a vertical synchronization signal Vsync has been input, the processing proceeds to step S620, and if a vertical synchronization signal Vsync has not been input, the processing proceeds to step S470. If a vertical synchronization signal Vsync has been input, a transition from the idle period to a display update period is made.

[0083] In step S610, it is determined whether incomplete sensor data DS exists in the sensor data storage unit 241 in the coordinate calculation unit 240. If incomplete sensor data DS exists, the process proceeds to step S620. If incomplete sensor data DS does not exist, the process proceeds to step S630. In step S620, the incomplete sensor data DS is discarded (deleted) from the sensor data storage unit 241. In step S630, the second driving is performed. As a result, in the display update period that appears immediately after the idle period, touch detection processing is performed in the four original touch detection periods 81 to 84 and the four additional touch detection periods 81a to 84a, as shown in part B of FIG. 15. At this time, transmission (report) of coordinate data PD to the host 30 is performed twice during the display update period. After step S630 is completed, the process returns to step S410.

[0084] In step S470, 1 is added to the count value Cnt described above. Then, it is determined whether or not the count value Cnt is 4 (step S480). As a result, if the count value Cnt is 4, the process proceeds to step S490, and if the count value Cnt is not 4, the process returns to step S440. In step S490, the count value Cnt is set to 0. The reason why steps S470 to S490 are performed in this manner is because all of the multiple pieces of sensor data DS corresponding to the multiple sensor electrodes 150 are acquired by the touch detection process performed during four touch detection periods.

[0085] When the process moves to step S500, the complete sensor data DS has been stored in the sensor data storage unit 241 in the coordinate calculation unit 240. Therefore, in step S500, a report is made of the results obtained based on the complete sensor data DS. After step S500 is completed, the process returns to step S430.

[0086] <2.2.3 Specific examples> Hereinafter, how the liquid crystal display device 1 according to this embodiment is driven depending on the length of the pause period will be described.

[0087] Referring to FIG. 17, the operation when the idle period is 20 milliseconds will be described. In this case, since no vertical synchronization signal Vsync is input from the host 30 within the second predetermined time from time t51 when the last line is written, the display update period transitions to the idle period. Note that, when the display update period transitions to the idle period, a report is generated based on the results of the touch detection process performed during the display update period. Since no vertical synchronization signal Vsync is input from the host 30 between time t52 when the last touch detection process performed in the display update period ends and time t53 when the third predetermined time has elapsed, the touch detection process starts at time t53. Thereafter, the state in which no vertical synchronization signal Vsync is input from the host 30 continues for a while. During the idle period, a report is generated every four touch detection periods. In the example shown in FIG. 17, a report is generated after the touch detection process ends at time t54 and after the touch detection process ends at time t55. After the touch detection process starts at time t56, a vertical synchronization signal Vsync is input from the host 30 before the touch detection process ends (at time t57). This causes a transition from the pause period to the display update period. At this time, the incomplete sensor data DS stored in the sensor data storage unit 241 in the coordinate calculation unit 240 is discarded. Then, the second driving described above is performed during the display update period from time t57 to time t58. Thereafter, the same operation as in the normal display update period is performed.

[0088] As shown in the following equation (7), the post-pause report rate R in this case (the report rate during the period indicated by the arrow marked with symbol T105) is 171.4 Hz. R = (1 / ((3.34 + 8.33) / 2)) × 1000 =171.4 (7)

[0089] With reference to FIG. 18, the operation when the idle period is 8 milliseconds will be described. In this case, the fourth touch detection process is started at time t61 during the idle period. Thereafter, a vertical synchronization signal Vsync is input from the host 30 before the touch detection process ends (at time t62). This causes a transition from the idle period to the display update period. At this time, the incomplete sensor data DS accumulated in the sensor data holding unit 241 in the coordinate calculation unit 240 is discarded. Then, the second driving described above is performed during the display update period from time t62 to time t63. Thereafter, the same operation as during the normal display update period is performed.

[0090] As shown in the following equation (8), the post-pause report rate R in this case (the report rate during the period indicated by the arrow with reference symbol T106) is 122.5 Hz. R=(1 / ((8+8.33) / 2))×1000 =122.5 (8)

[0091] With reference to FIG. 19, the operation when the idle period is 10.1 milliseconds will be described. In this case, the fourth touch detection process ends at time t71 during the idle period. As a result, a report is generated based on the results obtained from the four touch detection processes. After that, the vertical synchronization signal Vsync is not input from the host 30 until a first predetermined time has elapsed from time t71, the end point of the four touch detection processes (i.e., the end point of complete touch detection). However, the vertical synchronization signal Vsync is input from the host 30 until a third predetermined time has elapsed from time t71, the end point of the four touch detection processes (at time t72). This causes a transition from the idle period to the display update period. At this time, the sensor data holding unit 241 in the coordinate calculation unit 240 does not contain incomplete sensor data DS. Therefore, the process of discarding the incomplete sensor data DS is not performed, and the second driving described above is performed during the display update period from time t72 to time t73. Thereafter, the same operation as in the normal display update period is performed.

[0092] As shown in the following equation (9), the post-pause report rate R in this case (the report rate during the period indicated by the arrow with reference symbol T107) is 198.0 Hz. R=(1 / ((1.77+8.33) / 2))×1000 =198.0 (9)

[0093] With reference to FIG. 20, the operation when the idle period is 5 milliseconds will be described. In this case, the second touch detection process ends at time t81 during the idle period. After that, a vertical synchronization signal Vsync is input from the host 30 between time t81, when the second touch detection process ends, and the third predetermined time has elapsed (at time t82). This causes a transition from the idle period to the display update period. At this time, the incomplete sensor data DS (sensor data DS obtained in the first two touch detection processes) stored in the sensor data holding unit 241 in the coordinate calculation unit 240 is discarded. Then, the second driving described above is performed during the display update period from time t82 to time t83. Thereafter, the same operation as during the normal display update period is performed.

[0094] As shown in the following equation (10), the post-pause report rate R in this case (the report rate during the period indicated by the arrow with reference symbol T108) is 150.0 Hz. R=(1 / ((5+8.33) / 2))×1000 =150.0 (10)

[0095] Referring to FIG. 21, the operation when the idle period is 1 millisecond will be described. In this case, since no vertical synchronization signal Vsync is input from the host 30 within the second predetermined time from time t91 when writing to the final line is performed, the display update period transitions to the idle period. Note that, when the display update period transitions to the idle period, a report is generated based on the results of the touch detection process performed during the display update period. A vertical synchronization signal Vsync is input from the host 30 between time t92 (the end time of complete touch detection) of the fourth touch detection process performed during the display update period and time t93 (the end time of complete touch detection) before the first predetermined time has elapsed. As a result, the idle period transitions to the display update period at time t93 without performing any touch detection process during the idle period. Then, the first driving described above is performed during the display update period from time t93 to time t94. However, since a long horizontal blanking interval is provided during the idle period, it is not necessary to provide a long horizontal blanking interval immediately after the start of the display update period. From time t94 onward, the same operation as during a normal display update period is performed.

[0096] As shown in the following equation (11), the post-pause report rate R in this case (the report rate during the period indicated by the arrow with reference symbol T109) is 107.2 Hz. R = (1 / ((1+8.33) / 1)) × 1000 =107.2 (11)

[0097] In the above example, the post-pause report rate R becomes the minimum when a vertical synchronization signal Vsync is input from the host 30 immediately before 1.67 milliseconds (first predetermined time) elapses from the end of the previous complete touch detection (the end of the fourth touch detection process in the display update period immediately before the pause period, or the end of the (4×K)th touch detection process in the pause period, where K is an integer greater than or equal to 1). In this case, the post-pause report rate R is 100.0 Hz, as shown in the following equation (12). Therefore, a report rate of 100.0 Hz or higher is guaranteed. R = (1 / ((1.67 + 8.33) / 1)) × 1000 =100.0 (12)

[0098] <2.3 Effects> According to this embodiment, in a liquid crystal display device 1 equipped with an in-cell touch panel, touch detection processing is repeated at predetermined time intervals during a pause period until a vertical synchronization signal Vsync is input from the host 30. Furthermore, if a vertical synchronization signal Vsync is input from the host 30 after a first predetermined time has elapsed since the most recent complete touch detection during the pause period, touch detection processing is performed at a predetermined timing (specifically, the timing after the end of the video signal write period) during the display update period that appears immediately after the pause period, as well as the timing immediately after the end of the pause period and the timing of a long horizontal blanking period provided between the touch detection period and the video signal write period. As described above, similar to the first embodiment, a sufficient report rate can be maintained even when variable low frame rate driving is performed in a liquid crystal display device 1 equipped with an in-cell touch panel.

[0099] <2.4 Modifications> In the second embodiment, if the vertical synchronization signal Vsync is input from the host 30 during a pause period after the first predetermined time has elapsed since the most recent complete touch detection, an additional touch detection period is provided in the display update period that appears immediately after the pause period. However, instead of this, if incomplete sensor data DS is discarded (deleted), an additional touch detection period may be provided in the display update period that appears immediately after the pause period. In this regard, assuming that all of the sensor data DS corresponding to each of the plurality of sensor electrodes 150 is acquired during P touch detection periods (here, P is an integer greater than or equal to 2) during which touch detection processing is performed, the incomplete sensor data DS is discarded when the vertical synchronization signal Vsync is input from the host 30 while touch detection processing is being performed during the pause period, or when the vertical synchronization signal Vsync is input from the host 30 when the number of touch detection processing operations since the end of the most recent complete touch detection during the pause period is 1 or more and (P-1) or less. From the above, when a vertical synchronization signal Vsync is input from the host 30 while touch detection processing is being performed during a pause period, or when a vertical synchronization signal Vsync is input from the host 30 when the number of times touch detection processing has been performed since the end of the complete touch detection performed immediately before during the pause period is 1 or more and (P-1) or less, an additional touch detection period may be provided in the display update period that appears immediately after the pause period.

[0100] With reference to the flowchart shown in FIG. 22, differences from the second embodiment (see FIG. 16) regarding processing after the point at which writing to the final line is performed during a display update period will be described. In this modification, the processing of step S430 in the second embodiment is not provided. Therefore, if it is determined in step S420 that no vertical synchronization signal Vsync has been input from the host 30 until the second predetermined time has elapsed since writing to the final line, the processing proceeds to step S440. Also, after reporting the results obtained based on the complete sensor data DS in step S500, the processing returns to step S440. Also, in this modification, if it is determined in step S610 that incomplete sensor data DS does not exist in the sensor data storage unit 241 in the coordinate calculation unit 240, the processing proceeds to step S510. Since the first drive (see part A in FIG. 15) is performed in step S510, ultimately, if incomplete sensor data DS does not exist in the sensor data storage unit 241, no additional touch detection period is provided in the display update period that appears immediately after the pause period. On the other hand, if incomplete sensor data DS exists in the sensor data holding unit 241, the incomplete sensor data DS is discarded, and the second driving (see part B of FIG. 15) is performed. In this way, when the incomplete sensor data DS is discarded, an additional touch detection period is provided in the display update period that appears immediately after the pause period.

[0101] According to this modification as described above, it is also possible to maintain a sufficient report rate even when variable low frame rate driving is performed in the liquid crystal display device 1 equipped with an in-cell touch panel.

[0102] <3.Other> Although the present invention has been described in detail above, the above description is illustrative in all respects and is not restrictive. It is understood that many other changes and modifications can be made without departing from the scope of the present invention. For example, in the second embodiment, a series of periods consisting of a long horizontal blanking period, a video signal writing period, and a touch detection period is repeated four times in a normal display update period (see part A of FIG. 15 ), but the number of times that the series of periods is repeated may be other than four. [Explanation of symbols]

[0103] 1...Liquid crystal display device 10...LCD touch panel 20...PCB 30...Host 100...Drive unit 101...Display section 110...Source driver 120...Touch detection circuit 130...Gate driver 150...Sensor electrode 210...Timing controller 220...Level shifter IC 230...Sensor electrode potential control IC 240...Coordinate calculation unit (MCU) 241...Sensor data storage unit GL: Gate bus line SL...Source bus line SNL…Sensing Line Vsync…Vertical synchronization signal

Claims

1. A display device including a touch panel including a plurality of sensor electrodes provided for detecting a touch position, a plurality of video signal lines for transmitting video signals; a plurality of scanning signal lines intersecting the plurality of video signal lines; a plurality of pixel formation portions, each including a capacitance, provided at each intersection of the plurality of video signal lines and the plurality of scanning signal lines; a video signal line drive circuit that applies the video signals to the plurality of video signal lines; a scanning signal line driving circuit that selectively drives the plurality of scanning signal lines; a touch detection circuit that performs touch detection processing by applying drive signals to the plurality of sensor electrodes to acquire sensor data for identifying a touch position; a timing control circuit that controls operations of the video signal line drive circuit, the scanning signal line drive circuit, and the touch detection circuit; Equipped with the timing control circuit is configured to be able to control operations of the video signal line drive circuit, the scanning signal line drive circuit, and the touch detection circuit so that a display update period in which a display image is updated by writing the video signal to the capacitor included in each of the plurality of pixel formation portions and a pause period of any length and variable length in which the display image is not updated are generated; When a vertical synchronization signal is input from an external device during the idle period, the idle period transitions to the display update period, the timing control circuit controls an operation of the touch detection circuit so that the touch detection process is performed at least at a predetermined timing during the display update period, and so that the touch detection process is performed at a predetermined time interval during the pause period until the vertical synchronization signal is input from outside; a timing control circuit for controlling the operation of the touch detection circuit so that the touch detection process is performed at the timing immediately after the end of the pause period in addition to the predetermined timing during the display update period that appears immediately after the pause period, if the point at which the vertical synchronization signal is input from outside during the pause period is later than the point at which a first predetermined time has elapsed since the most recent point at which acquisition of all of the sensor data corresponding to each of the plurality of sensor electrodes was completed by the touch detection process.

2. The display device according to claim 1 , wherein all of the sensor data corresponding to each of the plurality of sensor electrodes is acquired during one touch detection period in which the touch detection process is performed.

3. all of the sensor data corresponding to each of the plurality of sensor electrodes are acquired during a plurality of touch detection periods during which the touch detection process is performed; 2. The display device according to claim 1, wherein if the vertical synchronization signal is input from outside during the idle period after the first predetermined time has elapsed since the most recent time at which acquisition of all of the sensor data corresponding to each of the plurality of sensor electrodes was completed by the touch detection process, the timing control circuit controls operation of the touch detection circuit so that the touch detection process is further performed at the timing of a flyback period that is provided between the touch detection period and a video signal write period in which the video signal is written to the capacitor.

4. a sensor data storage unit for storing the sensor data, and a coordinate calculation unit for calculating coordinates representing a touch position based on all of the sensor data corresponding to each of the plurality of sensor electrodes; the sensor data acquired by the touch detection process is stored in the sensor data storage unit; 2. The display device according to claim 1, wherein when the vertical synchronization signal is input from outside while the touch detection process is being performed during the pause period, the timing control circuit controls the operation of the touch detection circuit so that the touch detection process is interrupted and deletes the sensor data stored in the sensor data holding unit.

5. 2. The display device according to claim 1, wherein if the vertical synchronization signal is not input from outside by the time a second predetermined time has elapsed since the time when the process of writing the video signal to the capacitor for all of the plurality of pixel formation portions is completed during the display update period, a transition from the display update period to the pause period is performed.

6. 6. The display device according to claim 1, wherein, when obtaining all of the sensor data corresponding to each of the plurality of sensor electrodes by the touch detection process is defined as complete touch detection and the frequency at which complete touch detection is performed is defined as a touch rate, the first predetermined time is set so that the touch rate during a period from an end point of a last complete touch detection before a start point of a first display update period after a transition from the pause period to the display update period to an end point of the first display update period after the transition satisfies a target lower limit value.

7. 7. The display device according to claim 6, wherein the target lower limit is 100 Hz.

8. A display device including a touch panel including a plurality of sensor electrodes provided for detecting a touch position, a plurality of video signal lines for transmitting video signals; a plurality of scanning signal lines intersecting the plurality of video signal lines; a plurality of pixel formation portions, each including a capacitance, provided at each intersection of the plurality of video signal lines and the plurality of scanning signal lines; a video signal line drive circuit that applies the video signals to the plurality of video signal lines; a scanning signal line driving circuit that selectively drives the plurality of scanning signal lines; a touch detection circuit that performs touch detection processing by applying drive signals to the plurality of sensor electrodes to acquire sensor data for identifying a touch position; a timing control circuit that controls operations of the video signal line drive circuit, the scanning signal line drive circuit, and the touch detection circuit; Equipped with the timing control circuit is configured to be able to control operations of the video signal line drive circuit, the scanning signal line drive circuit, and the touch detection circuit so that a display update period in which a display image is updated by writing the video signal to the capacitor included in each of the plurality of pixel formation portions and a pause period of any length and variable length in which the display image is not updated are generated; When a vertical synchronization signal is input from an external device during the idle period, the idle period transitions to the display update period, the timing control circuit controls an operation of the touch detection circuit so that the touch detection process is performed at least at a predetermined timing during the display update period, and so that the touch detection process is performed at a predetermined time interval during the pause period until the vertical synchronization signal is input from outside; all of the sensor data corresponding to each of the plurality of sensor electrodes is acquired during P touch detection periods in which the touch detection process is performed, where P is an integer equal to or greater than 2; When complete touch detection is defined as acquiring all of the sensor data corresponding to each of the plurality of sensor electrodes by the touch detection process, if the vertical synchronization signal is input from outside while the touch detection process is being performed in the idle period and if the vertical synchronization signal is input from outside when the number of times the touch detection process has been performed since the end of the complete touch detection performed immediately before in the idle period is one or more and (P-1) or less, the timing control circuit controls the operation of the touch detection circuit so that the touch detection process is performed not only at the predetermined timing during the display update period that appears immediately after the idle period but also at the timing immediately after the end of the idle period and at the timing of a flyback period that is provided between the touch detection period and a video signal write period in which the video signal is written to the capacitor.

9. A method for driving a display device having a touch panel including a plurality of sensor electrodes provided for detecting a touch position, comprising: The display device includes: a plurality of video signal lines for transmitting video signals; a plurality of scanning signal lines intersecting the plurality of video signal lines; a plurality of pixel formation portions, each including a capacitance, provided at each intersection of the plurality of video signal lines and the plurality of scanning signal lines; a video signal line drive circuit that applies the video signals to the plurality of video signal lines; a scanning signal line driving circuit that selectively drives the plurality of scanning signal lines; a touch detection circuit that performs touch detection processing by applying drive signals to the plurality of sensor electrodes to acquire sensor data for identifying a touch position; a timing control circuit that controls operations of the video signal line drive circuit, the scanning signal line drive circuit, and the touch detection circuit; Equipped with The driving method includes: a display updating step in which the timing control circuit controls operations of the video signal line driving circuit and the scanning signal line driving circuit so that a display image is updated by performing a video signal writing process in which the video signal is written into the capacitor included in each of the plurality of pixel formation portions; a pause step in which the timing control circuit controls the operations of the video signal line drive circuit and the scanning signal line drive circuit so that the video signal writing process is paused throughout a pause period of any length and variable length; Including, In the display update step, the timing control circuit controls the operation of the touch detection circuit so that the touch detection process is performed at least at a predetermined timing; In the pause step, the timing control circuit controls the operation of the touch detection circuit so that the touch detection process is performed at predetermined time intervals during the pause period until a vertical synchronization signal is input from outside; a timing control circuit for controlling the operation of the touch detection circuit so that, in the next display update step, the touch detection process is performed at a timing immediately after the end of the idle period in addition to the predetermined timing, if the point at which the vertical synchronization signal is input from outside during the idle period is later than a point at which a first predetermined time has elapsed since the most recent point at which acquisition of all of the sensor data corresponding to each of the plurality of sensor electrodes was completed by the touch detection process.

10. A method for driving a display device having a touch panel including a plurality of sensor electrodes provided for detecting a touch position, comprising: The display device includes: a plurality of video signal lines for transmitting video signals; a plurality of scanning signal lines intersecting the plurality of video signal lines; a plurality of pixel formation portions, each including a capacitance, provided at each intersection of the plurality of video signal lines and the plurality of scanning signal lines; a video signal line drive circuit that applies the video signals to the plurality of video signal lines; a scanning signal line driving circuit that selectively drives the plurality of scanning signal lines; a touch detection circuit that performs touch detection processing by applying drive signals to the plurality of sensor electrodes to acquire sensor data for identifying a touch position; a timing control circuit that controls operations of the video signal line drive circuit, the scanning signal line drive circuit, and the touch detection circuit; Equipped with The driving method includes: a display updating step in which the timing control circuit controls operations of the video signal line driving circuit and the scanning signal line driving circuit so that a display image is updated by performing a video signal writing process in which the video signal is written into the capacitor included in each of the plurality of pixel formation portions; a pause step in which the timing control circuit controls the operations of the video signal line drive circuit and the scanning signal line drive circuit so that the video signal writing process is paused throughout a pause period of any length and variable length; Including, In the display update step, the timing control circuit controls the operation of the touch detection circuit so that the touch detection process is performed at least at a predetermined timing; In the pause step, the timing control circuit controls the operation of the touch detection circuit so that the touch detection process is performed at predetermined time intervals during the pause period until a vertical synchronization signal is input from outside; all of the sensor data corresponding to each of the plurality of sensor electrodes is acquired during P touch detection periods in which the touch detection process is performed, where P is an integer equal to or greater than 2; If complete touch detection is defined as obtaining all of the sensor data corresponding to each of the plurality of sensor electrodes by the touch detection process, when the vertical synchronization signal is input from outside while the touch detection process is being performed during the idle period and when the vertical synchronization signal is input from outside when the number of times the touch detection process has been performed since the end of the complete touch detection performed immediately before during the idle period is one or more and (P-1) or less times, in the display update step that is subsequently performed, the timing control circuit controls the operation of the touch detection circuit so that the touch detection process is performed at the predetermined timing, as well as immediately after the end of the idle period and at the timing of a retrace period that is provided between the touch detection period and a video signal write period in which the video signal is written to the capacitor.

Images