WO2013047456A1

WO2013047456A1 - Display device, method for driving same, and display system provided with display device

Info

Publication number: WO2013047456A1
Application number: PCT/JP2012/074435
Authority: WO
Inventors: 齊藤　浩二; 章純藤岡; 佳典柴田; 正実尾崎
Original assignee: シャープ株式会社
Priority date: 2011-09-27
Filing date: 2012-09-24
Publication date: 2013-04-04
Also published as: TW201317973A

Abstract

The purpose of the present invention is to provide a display device for improving touch panel detection accuracy and reducing power consumption. The display device drives at least part of a display element through interlaced scanning by alternatingly repeating a scanning period and a horizontal blanking period at least as long as the minimum period necessary for detection operation of an external detection device, outputs a detection instruction signal for instructing detection to the detection device during the horizontal blanking period, and does not output a detection instruction signal during the scanning period.

Description

Display device, driving method thereof, and display system including the display device

The present invention relates to a display device, a driving method thereof, and a display system including the display device.

In recent years, thin, lightweight, and low power consumption display devices typified by liquid crystal display devices have been actively used. Such a display device is remarkably mounted on, for example, a mobile phone, a smart phone, or a laptop PC (Personal Computer). In the future, electronic paper, which is a thinner display device, is expected to develop and spread rapidly. Under such circumstances, it is currently a common problem to reduce power consumption in various display devices.

Patent Document 1 discloses a display device that achieves low power consumption by providing a non-scanning period longer than the scanning period for scanning the screen once, and providing a pause period in which all scanning signal lines are in a non-scanning state. A driving method is disclosed.

Also, a touch panel provided on the display screen of the display device is actively used (for example, Patent Document 2). The touch panel is a position input device that detects a position on a display screen instructed by a user's finger or a pen and outputs the detected position information. Since the touch panel can be operated intuitively as compared with an input device such as a keyboard or a mouse, the touch panel is conspicuously mounted on, for example, a mobile phone, a smartphone, or a tablet PC.

One method for improving the detection accuracy of the touch panel is a method of preventing the influence of noise from the display device by performing the touch panel detection operation during the vertical blanking period. For example, Japanese Patent Application No. 2011-86813 discloses a method of improving detection accuracy by increasing the number of touch panel detections by providing two vertical blanking periods in one frame period. According to the above method, the touch panel detection operation can be performed at a frequency equal to or higher than the refresh rate of the display device, and the detection accuracy can be improved.

Japanese Patent Publication “Japanese Patent Laid-Open No. 2001-31253 (published on November 9, 2001)” Japanese Patent Publication “Japanese Patent Laid-Open No. 2001-060079 (published March 6, 2001)”

However, in the method of performing the touch panel detection operation during the vertical blanking period, it is necessary to secure a long vertical blanking period, which increases the cost by mounting the frame memory or increases the power consumption by increasing the frequency of the logic circuit. There's a problem. These problems become more prominent as the display device has higher resolution.

Accordingly, the present invention has been made in view of the above problems, and an object of the present invention is to improve a touch panel detection accuracy and reduce power consumption, a driving method thereof, and the display device. It is to provide a display system provided.

In order to solve the above problems, a display device according to one embodiment of the present invention includes a display element that displays an image on a screen, a scanning period in which scanning is performed, and a horizontal blanking period in which the scanning is paused. The display element is driven so as to alternately repeat a horizontal blanking period having a length of the minimum period required for a detection operation in an external detection device, and at least a part of the display element is driven by interlace scanning. A driving unit; and an output unit that outputs a detection instruction signal instructing detection to the external detection device in the horizontal blanking period and that does not output the detection instruction signal in the scanning period. It is characterized by having.

A display device driving method according to one embodiment of the present invention is a driving method of a display device including a display element that displays an image on a screen in order to solve the above-described problem. The display element is driven so as to alternately repeat a horizontal blanking period in which the scanning is stopped, and at least a horizontal blanking period having the length of the shortest period necessary for the detection operation in the external detection device. In addition, in the driving step of driving the display element by interlaced scanning and the horizontal blanking period, a detection instruction signal instructing detection is output to the external detection device, and in the scanning period, And an output step of not outputting the detection instruction signal.

According to the above configuration and method, the detection instruction signal is output to the detection device for each horizontal blanking period, and when the detection instruction signal is output, the detection device performs a detection operation. Since the horizontal blanking period is provided between the scanning period and the scanning period, the detection device can perform a detection operation at a frequency much higher than the refresh rate. As a result, the detection accuracy of the detection device can be greatly improved.

In particular, in one embodiment of the present invention, since the horizontal blanking period can be increased by performing interlaced scanning and the detection accuracy of the detection device can be improved, it is not necessary to mount a new member such as a frame memory, Power can be reduced.

In addition, if it is a display system provided with the display apparatus of the said structure and the detection apparatus which detects based on the detection instruction signal from this display apparatus, there can exist an effect similar to the above-mentioned effect.

Other objects, features, and superior points of the present invention will be fully understood from the following description. The advantages of the present invention will become apparent from the following description with reference to the accompanying drawings.

As described above, the display device according to one embodiment of the present invention can realize interlace scanning having a long horizontal blanking period, and thus outputs a detection instruction signal to an external detection device during the horizontal blanking period. Therefore, the number of detection operations in the detection apparatus can be increased, and the accuracy of detection results can be improved.

6 is a timing chart showing drive timing of each scanning signal line G when performing interlaced scanning according to an embodiment of the present invention. It is a block diagram which shows the detail of a structure of the display system which concerns on one Embodiment of this invention. It is a block diagram which shows the detail of a structure of the display system which concerns on one Embodiment of this invention. It is a figure which shows the structure of the pixel with which the display panel which concerns on one Embodiment of this invention is provided. It is a figure which shows the detail of a structure of the touchscreen which concerns on one Embodiment of this invention. 6 is a timing chart showing drive timing of each scanning signal line G when normal sequential scanning is performed. 6 is a timing chart showing drive timing of each scanning signal line G when normal interlace scanning is performed. 4 is a timing chart showing a control signal of a scanning line driving circuit and an output signal from the scanning line driving circuit according to an embodiment of the present invention. It is a figure which shows the characteristic of various TFT. 6 is a timing chart showing drive timing of each scanning signal line G when performing interlaced scanning according to an embodiment of the present invention. 4 is a timing chart showing a control signal of a scanning line driving circuit and an output signal from the scanning line driving circuit according to an embodiment of the present invention. It is the schematic which shows the display system which concerns on other embodiment of this invention. It is the schematic which shows the display system which concerns on other embodiment of this invention. 6 is a timing chart showing a control signal of a scanning line driving circuit and an output signal from the scanning line driving circuit according to another embodiment of the present invention.

Embodiments of the present invention will be described in detail based on the drawings. In the following description, members having the same function and action are denoted by the same reference numerals and description thereof is omitted.

[First Embodiment]
(Configuration of display system 1)
A configuration of the display system 1 according to the present embodiment will be described with reference to FIG. FIG. 2 is a block diagram showing details of the configuration of the display system 1 according to the present embodiment. As illustrated in FIG. 2, the display system 1 includes a display device 2, a touch panel 3, and a control unit 10. In the display system 1 of the present embodiment, the control unit 10 displays and outputs an image via the display device 2, acquires a user instruction via the touch panel 3, and performs various processes based on the acquired instruction. ing. In addition to video, arbitrary information such as still images or symbols may be displayed and output via the display device 2.

The display device 2 includes a display panel 2a (display element), a scanning line driving circuit 4 (driving unit), a signal line driving circuit 5 (driving unit), a common electrode driving circuit 6, and a timing control unit 7 (output unit). Have. Furthermore, the touch panel 3 includes a detection unit 8 and a detection unit control unit 9.

The display panel 2a includes a screen composed of a plurality of pixels arranged in a matrix. Further, the display panel 2a includes N (N is an arbitrary integer) scanning signal lines G (gate lines) for selecting and scanning the screen in a line-sequential manner. Further, the display panel 2a includes M (M is an arbitrary integer) data signal lines S (source lines) that supply data signals to pixels for one row included in the selected line. The scanning signal line G and the data signal line S cross each other.

G (n) shown in FIG. 2 represents the n-th scanning signal line G (n is an integer from 1 to N). For example, G (1), G (2), and G (3) represent the first, second, and third scanning signal lines G, respectively. On the other hand, S (i) represents the i-th data signal line S (i is an integer from 1 to M). For example, S (1), S (2), and S (3) represent the first, second, and third data signal lines S, respectively.

The scanning line driving circuit 4 sequentially scans each scanning signal line G from the top to the bottom of the screen, for example. At this time, a rectangular wave for turning on a switching element (TFT) provided in the pixel and connected to the pixel electrode is output to each scanning signal line G. Thereby, the pixels for one row in the screen are selected.

However, the scanning in the scanning line driving circuit 4 is not limited to the above-described sequential scanning. For example, after scanning the first, third, fifth,... And odd-numbered scanning signal lines G, interlaced scanning (interlaced scanning) that scans the second, fourth, sixth,... ) Can also be performed.

The signal line driving circuit 5 receives the video signal (arrow C) input from the control unit 10 to the timing control unit 7 from the timing control unit 7 (arrow E). The signal line drive circuit 5 calculates the value of the voltage to be output to each pixel for the selected row from the video signal input from the timing control unit 7, and the voltage of that value is applied to each data signal line S. Output. As a result, image data is supplied to each pixel on the selected scanning signal line G.

The display device 2 includes a common electrode (not shown) provided for each pixel in the screen. The common electrode driving circuit 6 outputs a predetermined common voltage for driving the common electrode to the common electrode based on a signal (arrow A) input from the timing control unit 7 (arrow B).

Based on the clock signal, the horizontal synchronization signal, and the vertical synchronization signal (arrow C) input from the control unit 10, the timing control unit 7 supplies a signal serving as a reference for each circuit to operate in synchronization with each circuit. Output. Specifically, the gate start pulse signal GSP, the gate clock signal GCK, and the gate output enable signal GOE are output to the scanning line driving circuit 4 based on the clock signal, the horizontal synchronization signal, and the vertical synchronization signal. (Arrow D). A source start pulse signal SSP, a source latch strobe signal SLS, and a source clock signal SCK are output to the signal line driver circuit 5 based on the clock signal, horizontal synchronization signal, and vertical synchronization signal (arrow E).

The scanning line driving circuit 4 starts scanning the display panel 2a with the gate start pulse signal GSP received from the timing control section 7 as a cue, and shifts the selection state of the scanning signal line G, which is a gate clock signal GCK. The selection voltage is sequentially applied to each scanning signal line G. Based on the source start pulse signal SSP received from the timing control unit 7, the signal line drive circuit 5 stores the input image data of each pixel in a register according to the source clock signal SCK. Then, after storing the image data, the signal line driving circuit 5 writes the image data to each data signal line S of the display panel 2a in accordance with the next source latch strobe signal SLS. For example, an analog amplifier included in the signal line driving circuit 5 is used for writing the image data.

In the touch panel 3, a detection unit 8 is provided in the vicinity of the screen of the display panel 2a of the display device 2, and detects a position on the screen instructed by a user's finger or the like. The detection unit control unit 9 controls the detection unit 8. Specifically, the detection unit control unit 9 drives the detection unit 8 via the drive line Tx, that is, inputs a rectangular wave. The detection unit 8 transmits a detection signal to the detection unit control unit 9 via the sense line Rx based on the input rectangular wave. Here, when an instruction of a position on the touch panel is generated by the user's finger or the like, the detection unit in a form in which a signal by a rectangular wave and a signal by the user's finger or the like are superimposed on the sense line Rx in the vicinity thereof. It is transmitted to the control unit 9. The detection unit control unit 9 creates detection data indicating the detected position based on the superimposed signal and transmits the detection data to the control unit 10 (arrow G).

The control unit 10 recognizes a user operation based on the detection data from the touch panel 3, transmits a video signal and a video synchronization signal to the display device 2 in order to control display of the display device 2, etc. Various processes are performed.

Note that a voltage necessary for each circuit in the display system 1 to operate is supplied from, for example, a power generation circuit (not shown), but this power generation circuit may be included in the control unit 10. In this case, each voltage is supplied from the control unit 10 to the display device 2, and each voltage is supplied from the control unit 10 to the touch panel 3. As an example of a voltage necessary for each circuit in the display system 1 to operate, the power supply voltage Vdd is supplied to the signal line driving circuit 5.

In this specification, a period during which the scanning line driving circuit 4 scans one scanning signal line G, that is, a period during which image data is supplied to each pixel on the selected scanning signal line G is referred to as one scanning period. Call it. A horizontal blanking period is provided between two consecutive scanning periods. The horizontal blanking period is a period from the scanning of one scanning signal line G to the start of scanning of the next scanning signal line G. During the horizontal blanking period, scanning of the display by the scanning line driving circuit 4 is paused. One horizontal period is a period obtained by combining one scanning period and one horizontal blanking period.

The timing control unit 7 outputs a detection instruction signal (arrow F) that is a signal for instructing a detection operation in the touch panel 3 to the detection unit control unit 9 of the touch panel 3 during the horizontal blanking period. In the touch panel 3, when the detection unit control unit 9 receives the detection instruction signal from the timing control unit 7 of the display device 2, the detection unit 8 performs a detection operation, and the detection data indicating the detection result is detected by the detection unit control unit 9. Is output to the control unit 10.

(Modification of display system 1)
FIG. 3 is a block diagram showing details of the configuration of the display system 1 ′ according to the present embodiment. The difference between the display system 1 and the display system 1 ′ is the path of the detection instruction signal. As described above, in the display system 1 of FIG. 2, the detection instruction signal is directly output from the timing control unit 7 of the display device 2 to the detection unit control unit 9 of the touch panel 3.

In contrast, in the display system 1 ′ of FIG. 3, a detection instruction signal is output from the timing control unit 7 of the display device 2 to the detection unit control unit 9 of the touch panel 3 via the control unit 10. Specifically, the timing control unit 7 of the display device 2 outputs a first detection instruction signal (arrow F1) to the control unit 10. Next, the control unit 10 that has received the first detection instruction signal outputs to the detection unit control unit 9 of the touch panel 3 a second detection instruction signal (arrow F <b> 2) having substantially the same timing as the first detection instruction signal.

Thus, the detection operation of the touch panel 3 may be controlled via the control unit 10. In other words, any system that can detect the touch panel 3 during the horizontal blanking period of the display panel 2a may be used. That is, the effect of the present invention can be achieved by applying either the display system 1 or the display system 1 '.

(Pixel configuration)
Here, FIG. 4 shows a configuration of a pixel included in the display panel 2a. FIG. 4 shows a configuration of two pixels (pixel (i, n) and pixel (i + 1, n)) among a plurality of pixels included in the display panel 2a. Pixel (i, n) indicates a pixel connected to the data signal line S (i) and the scanning signal line G (n). Pixel (i + 1, n) indicates a pixel connected to the data signal line S (i + 1) and the scanning signal line G (n). The other pixels included in the display panel 2a have the same configuration as these pixels.

As shown in FIG. 4, the pixel includes a TFT 200 as a switching element. The gate electrode of the TFT 200 is connected to the corresponding scanning signal line G. The source electrode of the TFT 200 is connected to the corresponding data signal line S. The drain electrode of the TFT 200 is connected to the liquid crystal capacitor Clc and the storage capacitor Ccs. When pixel data is written to this pixel, an on-voltage is first supplied from the scanning signal line G to the gate electrode of the TFT 200. Thereby, the TFT 200 is switched to the on state. When a data signal is supplied from the corresponding data signal line S when the TFT 200 is on, the data signal is supplied from the drain electrode of the TFT 200 to the pixel electrode of the liquid crystal capacitor Clc and the storage capacitor Ccs.

In this manner, when the data signal is supplied to the pixel electrode of the liquid crystal capacitor Clc, the arrangement direction of the liquid crystal in which an electric field is applied between the pixel electrode of the liquid crystal capacitor Clc and the common electrode is supplied to the pixel. It changes in accordance with the difference between the voltage level of the received data signal and the voltage level supplied to the common electrode, and an image corresponding to this difference is displayed.

Further, when a data signal is supplied to the storage capacitor Ccs, a charge corresponding to the voltage of the data signal is stored in the storage capacitor Ccs. The pixel can maintain a state where an image is displayed for a certain period of time due to the charge stored in the storage capacitor Ccs.

As shown in FIG. 4, a parasitic capacitance Cgs and a parasitic capacitance Cgd are generated in each pixel. The parasitic capacitance Cgs is a parasitic capacitance generated at the intersection of the data signal line S and the scanning signal line G which are metal layers. The parasitic capacitance Cgd is a parasitic capacitance generated between the scanning signal line G and the drain electrode.

Moreover, in each pixel, a parasitic capacitance Csd1 and a parasitic capacitance Csd2 are generated. The parasitic capacitance Csd1 is a parasitic capacitance generated between the scanning signal line G and the drain electrode. The parasitic capacitance Csd2 is a parasitic capacitance generated between the adjacent scanning signal line G and the drain electrode.

(Configuration of touch panel 3)
In the present embodiment, a projected capacitive touch panel 3 is used. In the case of the projected capacitive touch panel 3, the detection unit 8 is formed by forming a matrix-like transparent electrode pattern made of ITO (Indium Tin Oxide) or the like on a transparent substrate such as glass or plastic.

FIG. 5 is a diagram showing details of the configuration of the touch panel 3 according to the present embodiment. As shown in FIG. 5, the touch panel 3 has drive lines Y (1) to Y (27) and sense lines X (1) to X (42). The detection unit 8 is driven via Y (1) to Y (27). Here, since the metals intersect in the vicinity of the intersections of the drive lines Y (1) to Y (27) and the sense lines X (1) to X (42), a parasitic capacitance C is generated. For simplification of the drawing, the number of drive lines Y is 27 and the number of sense lines X is 42. However, the present invention is not limited to this.

When the user's finger or the like touches or approaches the detection unit 8, the electrostatic capacity of a plurality of transparent electrode patterns in the vicinity thereof changes. Therefore, the detection unit control unit 9 sequentially scans the drive lines Y (1) to Y (27) line by line from the top to the bottom of the screen, and inputs a pulse waveform. When a pulse waveform is input to each drive line Y, the current or voltage on the sense line X changes via the parasitic capacitance C at the intersection. The degree of this change varies depending on whether the user's finger or the like is near the sense line X. The detection unit control unit 9 calculates and creates detection data as position information based on the degree of change, and transmits the detection data to the control unit 10. In this way, the touch panel 3 can detect the position on the screen designated by the user's finger or the like. In FIG. 5, the drive line Y is driven in a line-sequential manner. However, the present invention is not limited to this. Further, the detection unit control unit 9 may be configured to transmit data converted into digital data of analog data from the sense line to the control unit 10 so that the control unit 10 calculates and creates position information.

The touch panel 3 may detect that a user's finger or the like touches or approaches an arbitrary position on the screen. In this case, it is only necessary to detect contact or approach of the user's finger or the like, and it is not necessary to detect the position. In this embodiment, the projected capacitive touch panel 3 is used. However, any detection touch panel 3 such as a surface capacitive touch panel or a resistive film touch panel 3 can be used. In the case where the display system 1 includes the touch panel 3 that is easily affected by the drive of the display panel 2a, such as the projection capacitive method, by applying the display device 2 according to the present embodiment, The effect of the present invention can be expected.

(Scanning method of display device 2)
In the present embodiment, in order to improve the detection accuracy of the touch panel 3 and reduce the power consumption of the display system 1, the display device 2 performs interlaced scanning (interlace scanning). Details thereof will be described with reference to FIG. FIG. 1 is a timing chart showing the driving timing of each scanning signal line G when performing interlaced scanning according to the present embodiment.

As shown in FIG. 1, in interlace scanning, a frame (n-th frame) in which data scanning is performed on odd lines of the scanning signal line G and a frame (n + 1-th frame) in which even lines are performed are alternately repeated. This interlaced scanning has the advantage that the frequency of the horizontal synchronizing signal can be kept low because the number of lines scanned in one frame is halved compared to normal sequential scanning.

At this time, in this embodiment, the horizontal blanking period has at least the length of the shortest period necessary for the detection operation in the touch panel 3. For example, after a predetermined period has elapsed from the start of the scanning period of the scanning signal line G (1), at least a horizontal blanking period having the length of the shortest period necessary for the detection operation in the touch panel 3 is provided to perform scanning. The scanning period of the signal line G (3) starts. The shortest period necessary for the detection operation on the touch panel 3 is a period during which the rectangular wave is output to one drive line Y. Therefore, the horizontal blanking period only needs to have the length of the period during which the rectangular wave is output to at least one drive line Y.

Here, FIG. 6 shows a timing chart showing the drive timing of each scanning signal line G when performing normal sequential scanning. FIG. 7 is a timing chart showing the drive timing of each scanning signal line G when performing normal interlace scanning. As shown in FIG. 6, when normal sequential scanning is performed, the horizontal blanking period between the scanning period is short. Similarly, even when normal interlace scanning is performed, the horizontal blanking period between the scanning period is short.

In contrast, in the present embodiment, as described above, the horizontal blanking period has at least the length of the shortest period necessary for the detection operation in the touch panel 3. Therefore, in the scanning method of the present embodiment, the horizontal blanking period is longer than that of the conventional sequential scanning and interlace scanning. Therefore, the touch panel 3 can perform the detection operation within the horizontal blanking period.

From the timing control unit 7, a detection instruction signal is output to the detection unit control unit 9 for each horizontal blanking period. When the detection instruction signal is output, the detection unit control unit 9 controls the detection unit 8, Perform detection operation. Since the horizontal blanking period is provided between the scanning period and the scanning period, the touch panel 3 can perform the detection operation at a frequency much higher than the refresh rate. As a result, the detection accuracy of the touch panel 3 can be greatly improved.

Particularly in this embodiment, since interlace scanning is performed, a sufficient scanning period can be secured. Therefore, it is not necessary to mount a new member such as a frame memory, and power consumption can be suppressed.

(Driving method of display device 2)
FIG. 8 is a timing chart showing the control signal of the scanning line driving circuit 4 and the output signal from the scanning line driving circuit 4. FIG. 8 shows temporal changes of the gate clock signal GCK, the gate output enable signal GOE, and the scanning signals G1 to G7 in order from the top. The scanning signals G1 to G7 are rectangular waves output from the scanning line driving circuit 4 to the scanning signal lines G (1) to (7) in order to turn on the TFTs. Here, for simplification of the figure, only the scanning signals G1 to G7 are shown, but the present invention is not limited to this.

The gate output enable signal GOE rises when a predetermined period elapses from the fall of the gate clock signal GCK (immediately before the rise of the gate clock signal GCK), and falls after a predetermined period of the rise of the gate clock signal GCK. is there. When the gate output enable signal GOE rises, the current scanning signal G at the H level falls, and at the fall, the next scanning signal G rises. For example, when the gate output enable signal GOE falls, the scanning signal G1 rises, and the scanning signal line G (1) is selected. Then, when the gate output enable signal GOE rises, the scanning signal G1 falls, and the scanning signal line G (1) becomes non-selected. Thereafter, when the gate output enable signal GOE falls, the scanning signal G3 rises and the scanning signal line G (3) is selected. In this way, after the scanning signal G1 is output to the scanning signal line G (1), the scanning signal G3 is output to the scanning signal line G (3), thereby realizing interlaced scanning.

At this time, the gate clock signal GCK repeats the first period in which it is at the H level for the first time and the second period in which the gate clock signal GCK is at the H level for the second time shorter than the first time. The timing control unit 7 controls. Further, in the timing controller 7, the gate output enable signal GOE rises immediately before the gate clock signal GCK rises in the second period, and then after a predetermined period of rise of the gate clock signal GCK in the next first period. Control is performed so as to maintain the H level until it falls. In other words, the timing control unit 7 performs control so that the gate output enable signal GOE maintains the L level for one scanning period and then maintains the H level for one horizontal blanking period.

As described above, the timing control unit 7 controls the gate clock signal GCK and the gate output enable signal GOE, so that interlace scanning having a long horizontal blanking period can be realized. Note that while the gate output enable signal GOE is at the H level, all the scanning signals G are at the L level, and the driving of all the scanning signal lines G is suspended. That is, it is a horizontal blanking period.

Therefore, in the horizontal blanking period, the timing control unit 7 outputs a detection instruction signal to the detection unit control unit 9 for each horizontal blanking period. The touch panel 3 performs a detection operation within a period in which the detection instruction signal is at the H level. Therefore, the detection operation on the touch panel 3 can be performed at an arbitrary timing as long as it is longer than the shortest period necessary for the operation and the detection instruction signal is in the H level. That is, the detection period of the touch panel 3 can be changed variously.

Note that the gate output enable signal GOE itself may be output to the touch panel 3 as a detection instruction signal.

(TFT characteristics)
In order to further improve the detection accuracy of the touch panel 3, in the display device 2 of the present embodiment, it is preferable to employ a TFT using a so-called oxide semiconductor for the semiconductor layer as the TFT 200. This oxide semiconductor includes, for example, IGZO (InGaZnOx). The reason will be described with reference to FIG. FIG. 9 is a diagram showing characteristics of various TFTs. FIG. 9 shows the characteristics of a TFT using an oxide semiconductor, a TFT using a-Si (amorphous silicon), and a TFT using LTPS (Low Temperature Poly Silicon). In this figure, the horizontal axis (Vgh) indicates the voltage value of the on-voltage supplied to the gate in each TFT, and the vertical axis (Id) indicates the amount of current between the source and drain in each TFT. In particular, a period indicated as “TFT-on” in the figure indicates a period in which the transistor is on according to the voltage value of the on-voltage, and a period indicated as “TFT-off” in the figure. Indicates a period in which it is in an OFF state according to the voltage value of the ON voltage.

As shown in FIG. 9, a TFT using an oxide semiconductor has a higher current amount (that is, electron mobility) in an on state than a TFT using a-Si. Although not shown, specifically, a TFT using a-Si has an Id current of 1 uA when the TFT is turned on, whereas a TFT using an oxide semiconductor is used when the TFT is turned on. The Id current is about 20 to 50 uA. From this, it can be seen that a TFT using an oxide semiconductor has an electron mobility about 20 to 50 times higher in an on state than a TFT using a-Si, and has an excellent on-characteristic. .

From the above, in the display device 2 of the present embodiment, by using a TFT using an oxide semiconductor for each pixel, the on characteristics of the TFT of each pixel become very excellent. For this reason, the amount of electron movement when writing pixel data to each pixel can be increased, and the time required for writing can be further shortened. That is, the display device 2 according to the present embodiment can make the horizontal blanking period, which is the period during which the touch panel 3 performs the detection operation, longer, and therefore sufficiently ensure the period during which the touch panel 3 performs the detection operation. Can do. Therefore, the detection accuracy by the touch panel 3 can be further increased.

[Second Embodiment]
(Scanning method of display device 2)
Hereinafter, another scanning method for improving the detection accuracy of the touch panel 3 and reducing the power consumption of the display system 1 will be described. Details thereof will be described with reference to FIG. FIG. 10 is a timing chart showing the drive timing of each scanning signal line G when performing interlaced scanning according to the present embodiment.

As shown in FIG. 10, interlace scanning is also performed in this embodiment. Specifically, a frame (n-th frame) in which data scanning is performed on odd lines of the scanning signal line G and a frame (n + 1-th frame) performed on even lines are alternately repeated.

At this time, in this embodiment, one scanning period and one horizontal blanking period are substantially equivalent. Further, the scanning period and the horizontal blanking period are switched at a timing according to the gate clock signal GCK. For example, after a predetermined period has elapsed based on the gate clock signal GCK after the scanning period of the scanning signal line G (1) has started, the horizontal blanking period starts, and then the predetermined period based on the gate clock signal GCK. After the period elapses, the scanning period of the scanning signal line G (3) starts.

Here, as shown in FIGS. 6 and 7, the horizontal blanking period is short when normal sequential scanning and interlace scanning are performed. However, in the present embodiment, one scanning period and one horizontal blanking period are set substantially equal. Therefore, in the scanning method of the present embodiment, the horizontal blanking period is longer than that of the conventional sequential scanning and interlace scanning. Therefore, the touch panel 3 can perform the detection operation within the horizontal blanking period.

(Driving method of display device 2)
FIG. 11 is a timing chart showing control signals of the scanning line driving circuit 4 and output signals from the scanning line driving circuit 4. FIG. 11 shows temporal changes of the gate clock signal GCK, the gate output enable signal GOE, and the scanning signals G1 to G7 in order from the top. The scanning signals G1 to G7 are rectangular waves output from the scanning line driving circuit 4 to the scanning signal lines G (1) to (7) in order to turn on the TFTs. Here, for simplification of the figure, only the scanning signals G1 to G7 are shown, but the present invention is not limited to this.

The interlace scanning method is the same as that in the first embodiment described above, but the gate clock signal GCK is output as usual. Specifically, the gate clock signal GCK is output that repeats the third period that is at the H level for the third time. At this time, in the timing control unit 7, the gate output enable signal GOE rises immediately before the gate clock signal GCK rises in the third period, and then the predetermined period of the rise of the gate clock signal GCK in the next third period. Control is performed so as to maintain the H level until it falls later. Further, the gate output until the gate clock signal GCK rises immediately before the next third period rises and then falls after a predetermined period after the rise of the gate clock signal GCK in the next third period. Control is performed so as to maintain the enable signal GOEH level. In other words, the timing control unit 7 performs control so that the gate output enable signal GOE maintains the L level only for one scanning period and then maintains the H level for one horizontal blanking period.

As described above, the timing control unit 7 controls the gate output enable signal GOE, so that interlace scanning having a long horizontal blanking period can be realized. Note that while the gate output enable signal GOE is at the H level, all the scanning signals G are at the L level, and the driving of all the scanning signal lines G is suspended. That is, it is a horizontal blanking period. Therefore, in the horizontal blanking period, the touch panel 3 performs the detection operation as in the first embodiment.

In the present embodiment, if only the gate output enable signal GOE is controlled, interlaced scanning having a long horizontal blanking period can be realized. Therefore, the circuit of the display device 2 is configured in comparison with the first embodiment. It can be made simpler.

[Modification]
The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims. Therefore, some modified examples are shown below as modified examples of the above-described embodiment.

(Modification 1)
FIG. 12 is a schematic diagram showing a display system 11 according to another embodiment. As shown in FIG. 12, a plurality (two in FIG. 12) of scanning

line driving circuits

4a and 4b may be provided, and the scanning signal line G may be driven by the plurality of scanning

line driving circuits

4a and 4b. For example, the scanning line driving circuit 4a (first scanning line driving circuit) controls odd lines of the scanning signal lines G, and the scanning line driving circuit 4b (second scanning line driving circuit) controls even lines of the scanning signal lines G. Can be set to. According to this, the scanning line driving circuit 4a operates in the nth frame, and the scanning line driving circuit 4b operates in the (n + 1) th frame. In this manner, interlaced scanning can be realized by properly using the scanning line drive circuits (4a, 4b) used for the odd and even lines of the scanning signal line G. That is, one scanning line driving circuit 4 is controlled so as to drive the odd lines of the scanning signal line G in the nth frame and to drive the even lines of the scanning signal line G in the n + 1th frame. Since a circuit or the like is not necessary, the circuit of the display device 2 can be simplified.

The same applies to the data signal line S, and a plurality (three in FIG. 12) of signal line drive circuits 5a to 5c may be provided, and the data signal line S may be driven by the plurality of signal line drive circuits 5a to 5c.

(Modification 2)
FIG. 13 is a schematic diagram showing a display system 11 ′ according to another embodiment. The interlace scanning shown in the first and second embodiments may not be performed on the entire screen of the display panel 2a. Specifically, a part of the display panel 2a may be driven by interlaced scanning, and the remaining area may be driven by sequential scanning. For example, as shown in FIG. 13, in the upper half of the screen, display that does not require the touch panel 3 such as moving image display or text display is performed, and in the lower half of the screen, display that requires the touch panel 3 such as keyboard display is performed. . In this case, the interlace scanning is performed only in the area where the touch panel 3 performs the necessary display, and the normal sequential scanning may be performed in the other areas.

The driving method in this case will be described with reference to FIG. FIG. 14 is a timing chart showing control signals for the scanning line driving circuit 4 and output signals from the scanning line driving circuit 4. FIG. 14 shows temporal changes of the gate clock signal GCK, the gate output enable signal GOE, and the scanning signals G1 to GN in order from the top. The scanning signals G1 to GN are rectangular waves output from the scanning line driving circuit 4 to the scanning signal lines G (1) to G (N) in order to turn on the TFTs.

As shown in FIG. 14, the scanning signal lines G (1) to G (m + 3) included in the normal scanning area where the touch panel 3 performs unnecessary display are driven by normal sequential scanning. On the other hand, the scanning signal lines G (m + 4) to G (N) included in the interlaced scanning area where the touch panel 3 performs necessary display are driven by the interlaced scanning shown in the first or second embodiment.

The control unit 10 controls which scanning signal line G performs sequential scanning or interlace scanning. The control unit 10 outputs to the timing control unit 7 display area information indicating which area on the screen of the display panel 2 a does not require the touch panel 3 and which area the touch panel 3 performs necessary display. Based on the display area information, the timing control unit 7 performs normal driving for the scanning signal lines G corresponding to the display area (normal scanning area) where the touch panel 3 is unnecessary. On the other hand, for the scanning signal line G corresponding to the display area (interlaced scanning area) where the touch panel 3 is necessary, the gate clock signal GCK and the gate output enable signal GOE corresponding to the interlaced scanning are output to the scanning line driving circuit 4. This makes it possible to perform interlaced scanning only in the interlaced scanning region. As described above, if the scanning signal line G for performing the interlace scanning is appropriately selected according to the display area required by the touch panel 3, the interlace scanning can be partially performed.

The present invention is not limited to the above-described embodiments and modifications, and various modifications can be made within the scope indicated in the claims. In other words, embodiments obtained by appropriately combining technical means disclosed in different embodiments or modifications are also included in the technical scope of the present invention.

For example, the display panel 2a described above may be a liquid crystal panel including a liquid crystal layer. In this case, the display device 2 is a liquid crystal display device. Further, the pixel of the display panel 2a may include an organic electroluminescence (EL) diode that is an element that emits light with a luminance corresponding to the flowing current. In this case, the display device 2 is an organic EL display (organic electroluminescence display device). The organic EL display consumes a large amount of current in the scanning mode, and the influence of the drive signal in the organic EL display on the detection device increases. Therefore, if the display device 2 is applied to the organic EL display, it is more effective.

Note that the above-described display device 2 can also be suitably used for a display device having a higher resolution than 1920 × 1080 full high-definition (FHD) video. In the case of a display device with high resolution, since the load capacity is large, it is difficult to ensure the charging time of the pixel electrode in one scanning period. However, since the display device 2 performs interlaced scanning, it is easy to ensure the charging time of the pixel electrode. Therefore, the display device 2 having high display quality can be realized. In other words, the display device 2 can be suitably used for a high-definition display device of 200 ppi or more.

[Summary of Embodiment]
As described above, in order to solve the above problems, a display device according to one embodiment of the present invention includes a display element that displays an image on a screen, a scanning period in which scanning is performed, and a horizontal return in which the scanning is paused. The display element is driven so as to alternately repeat a horizontal blanking period having a length of the shortest period necessary for a detection operation in an external detection device, and at least of the display elements by interlace scanning. A detection instruction signal for instructing detection is output to the external detection device in the horizontal blanking period and driving means for driving a part, and the detection instruction signal is not output in the scanning period. And an output unit.

In the display device according to one embodiment of the present invention, the scanning period and the horizontal blanking period are substantially equal in length.

According to the above configuration, it is only necessary to switch between the scanning period and the horizontal blanking period at a timing according to the gate clock signal GCK, so that the circuit of the driving means can be simplified.

In the display device according to one embodiment of the present invention, the display element is a matrix-type display element including a plurality of pixel electrodes arranged in a matrix, and a plurality of data for driving the pixel electrodes. The scanning unit further includes a signal line and a plurality of scanning signal lines, and the driving unit includes a plurality of scanning line driving circuits that respectively drive different portions of the plurality of scanning signal lines. .

In the display device according to one embodiment of the present invention, the driving unit is arranged in a first scanning line driving circuit that drives the plurality of pixel electrodes arranged in the odd-numbered columns and in the even-numbered columns. In addition, a second scanning line driving circuit for driving the plurality of pixel electrodes is provided.

According to the above configuration, interlaced scanning can be realized by properly using a plurality of scanning line driving circuits. That is, to control which one of the scanning signal lines G is driven in the nth frame and which one of the scanning signal lines G is driven in the (n + 1) th frame for one scanning line driving circuit. Therefore, the circuit of the display device can be simplified.

In the display device according to one embodiment of the present invention, the driving unit drives a part of the display element by the interlaced scanning and drives the remaining area by sequential scanning.

According to the above configuration, the interlaced scanning may be partially executed, such as performing normal sequential scanning in the area where the detection device does not require display, and performing interlaced scanning in the area where the detection device performs the necessary display. it can.

In the display device according to one embodiment of the present invention, the resolution of the display element is higher than the resolution of 1920 × 1080.

Further, in the display device according to one embodiment of the present invention, the definition of the display element is 200 ppi or more.

In the case of a high-resolution display device, since the load capacity is large, it is difficult to ensure the charging time of the pixel electrode in one scanning period. However, according to the above configuration, since interlace scanning is performed, it is easy to ensure the charging time of the pixel electrode. Therefore, a display device having high display quality can be realized.

In the display device according to one embodiment of the present invention, the external detection device includes a plurality of sense lines and a plurality of drive lines intersecting the plurality of sense lines, and each of the drive lines. Is selected and scanned, and for each of the selected drive lines, a rectangular wave that drives each of the drive lines is output, and the shortest period necessary for the detection operation in the external detection device is one of the above This is a period in which the rectangular wave is output to the drive line.

According to the above configuration, a rectangular wave is output to at least one drive line in one horizontal blanking period. Thereby, high detection accuracy is obtained in the detection device.

The display device according to one embodiment of the present invention is characterized in that an oxide semiconductor is used for a semiconductor layer of each of the plurality of pixels included in the display element.

In the display device according to one embodiment of the present invention, the oxide semiconductor is preferably IGZO.

According to the above configuration, pixel data is written to each pixel by adopting a TFT using an oxide semiconductor (for example, IGZO) having a relatively high electron transfer amount as each TFT of the plurality of pixels. The amount of electron transfer at the time can be increased, and the time required for the writing can be shortened. Thereby, it is possible to sufficiently provide a horizontal blanking period during which the detection device performs a detection operation. Therefore, the detection accuracy by the detection device can be increased.

Note that examples of the display device according to one embodiment of the present invention include a liquid crystal display device and an organic electroluminescence (EL) display device. The organic EL display device consumes a large amount of current in the scanning mode, and the influence of the drive signal in the display device on the detection device increases. Thus, if the display device according to one embodiment of the present invention is applied to an organic EL display device, the effect is further improved.

Also, examples of the detection device include a touch panel provided on the screen of the display device.

Since the touch panel is provided close to the display device or inside the display device, the influence of the drive signal in the display device is large. Therefore, if a touch panel is used as the detection device, it is more effective.

The specific embodiments or examples made in the detailed description section of the invention are merely to clarify the technical contents of the present invention, and are limited to such specific examples and are interpreted in a narrow sense. It should be understood that various modifications may be made within the spirit of the invention and the scope of the following claims.

As described above, since the display device according to the present invention can realize interlaced scanning having a long horizontal blanking period, the detection instruction signal is output to an external detection device during the horizontal blanking period. Since the number of detection operations in the detection device can be increased and the accuracy of the detection result can be improved, the detection device can be applied to any display device that performs scanning.

1, 1 ′, 11, 11 ′ Display system 2 Display device 2a Display panel 3 Touch panel 4 Scan line drive circuit 5 Signal line drive circuit 6 Common electrode drive circuit 7 Timing control unit 8 Detection unit 9 Detection unit control unit 10 Control unit 200 TFT

Claims

A display element for displaying an image on the screen;
The scanning period in which scanning is performed and the horizontal blanking period in which the scanning is stopped, and the horizontal blanking period having at least the length of the shortest period necessary for the detection operation in the external detection device is alternately repeated. Driving means for driving the display element and driving at least a part of the display element by interlace scanning;
An output unit that outputs a detection instruction signal instructing detection to the external detection device in the horizontal blanking period and that does not output the detection instruction signal in the scanning period. Characteristic display device.
2. The display device according to claim 1, wherein the length of the scanning period and the horizontal blanking period are substantially equal.
The display element is a matrix type display element including a plurality of pixel electrodes arranged in a matrix.
A plurality of data signal lines and a plurality of scanning signal lines for driving the pixel electrode;
The display device according to claim 1, wherein the driving unit includes a plurality of scanning line driving circuits that respectively drive different parts of the plurality of scanning signal lines.
The driving means includes a first scanning line driving circuit that drives the plurality of pixel electrodes arranged in odd-numbered columns, and a second scanning line drive that drives the plurality of pixel electrodes arranged in even-numbered columns. The display device according to claim 3, further comprising a circuit.
5. The display device according to claim 1, wherein the driving unit drives a partial area of the display element by the interlace scanning, and drives the remaining area by sequential scanning. .
The display device according to any one of claims 1 to 5, wherein a resolution of the display element is higher than a resolution of 1920 × 1080.
The display device according to any one of claims 1 to 6, wherein the definition of the display element is 200 ppi or more.
The external detection device includes a plurality of sense lines and a plurality of drive lines intersecting with the plurality of sense lines. Each of the drive lines is selected and scanned. In addition, a square wave that drives each of the above drive lines is output,
The display according to any one of claims 1 to 7, wherein the shortest period necessary for the detection operation in the external detection device is a period during which the rectangular wave is output to one drive line. apparatus.
The display device according to any one of claims 1 to 8, wherein an oxide semiconductor is used for a semiconductor layer of each of a plurality of pixels constituting the display element.
The display device according to claim 9, wherein the oxide semiconductor is IGZO.
The display device according to any one of claims 1 to 10, wherein the display device is a liquid crystal display device.
The display device according to any one of claims 1 to 11, wherein the display device is an organic electroluminescence display device.
A display device according to any one of claims 1 to 12,
A display system comprising: a detection device that performs detection based on a detection instruction signal from the display device.
14. The display system according to claim 13, wherein the detection device is a touch panel provided on a screen of the display device.
A method of driving a display device including a display element that displays an image on a screen,
The display element is configured to alternately repeat a horizontal blanking period that is a scanning period during which scanning is performed and a horizontal blanking period during which scanning is paused, which is longer than the shortest period necessary for the detection operation in the external detection device. A driving step of driving and driving the display element by interlace scanning;
An output step of outputting a detection instruction signal instructing detection to the external detection device in the horizontal blanking period and not outputting the detection instruction signal in the scanning period. A driving method characterized by the above.