WO2019058491A1

WO2019058491A1 - Display device and method of driving same

Info

Publication number: WO2019058491A1
Application number: PCT/JP2017/034196
Authority: WO
Inventors: 将紀小原
Original assignee: シャープ株式会社
Priority date: 2017-09-22
Filing date: 2017-09-22
Publication date: 2019-03-28

Abstract

This display device is provided with: a display panel including a plurality of pixel circuits, each having an electro-optic device; a touch panel provided on the surface of the display panel; a display panel drive circuit; and a touch panel drive circuit. The display panel drive circuit writes a data voltage to the display panel during certain periods, and the touch panel drive circuit reads a signal from the touch panel during other periods. During display-off periods included in frame periods, the touch panel drive circuit reads a signal from the touch panel, and the display panel drive circuit writes, to all pixel circuits, a display-off voltage for stopping the electro-optic devices from emitting light. A compensation unit performs compensation processing on an input video signal so as to compensate for the differences in luminance between the electro-optic devices due to the differences between the lengths of the periods of light emission of the electro-optic devices.

Description

Display device and driving method thereof

The present invention relates to a display device, and more particularly to a display device provided with a pixel circuit including an electro-optical element and a touch panel.

In recent years, an organic EL display device provided with a pixel circuit including an organic electroluminescence (hereinafter, referred to as EL) element has been put to practical use. Moreover, the technique which provides a touch panel on the surface of an organic electroluminescent panel is also utilized. Hereinafter, an organic EL panel with a touch panel and an organic EL display device with a touch panel will be examined.

FIG. 12 is a cross-sectional view of an organic EL panel with a touch panel. In the organic EL panel 70 shown in FIG. 12, the top emission system is adopted. The display substrate of the organic EL panel 70 is formed of a gate electrode 72, a gate insulating film 73, a channel semiconductor layer 74, a drain / source electrode 75, a data line 76, an anode power wire 77, an interlayer insulating film 78, and a reflection on a glass substrate 71. It is obtained by forming the electrode 79, the organic layer 81, the interlayer insulating film 82, and the upper electrode 83. Contact holes 84 are formed in the interlayer insulating film 78. The upper electrode 83 is formed in a plane so as to face the reflective electrode 79 in all the pixel circuits. A cover glass 85, a polarizing plate 86, and a touch panel 87 are provided to cover the upper electrode 83, and nitrogen is filled between the display substrate and the cover glass 85. The drive current in the pixel circuit flows from the drain / source electrode 75 to the contact hole 84, the reflective electrode 79, the organic layer 81, and the upper electrode 83. The organic layer 81 emits light at a luminance corresponding to the drive current.

As a prior art, Patent Document 1 describes a liquid crystal display device in which photosensors in all pixels accumulate charge within a backlight off period.

Japan JP 2011-210254 A

The conventional touch panel organic EL display device performs display and sensing independently of each other by unique timing. For this reason, in the conventional organic EL display device with a touch panel, there is a problem that the sense sensitivity is reduced by the noise caused by the display, and the display quality is deteriorated by the noise caused by the sensing.

For example, when display is performed with the organic EL panel 70 shown in FIG. 12, drive current in all pixel circuits flows to the upper electrode 83, and the potential of the upper electrode 83 locally fluctuates. Along with this, follower noise occurs at the time of sensing, and the S / N ratio of sensing decreases. For this reason, if sensing is performed during display, the sense sensitivity is reduced by the drive noise 91 from the display substrate.

The touch panel 87 is formed with drive lines and sense lines (both not shown). During sensing, a predetermined voltage is applied to the drive line, and a change in capacitance (not shown) formed between the drive line and the sense line is detected. Since the voltage of the drive line changes in a pulsed manner, the voltage of the drive line changes rapidly. Along with this, the data voltage of the pixel circuit in the display substrate changes, and noise occurs in the data voltage. Therefore, when display is performed during sensing, the display quality is degraded by the drive noise 92 of the touch panel 87.

Therefore, it is an object to provide a display device with a touch panel in which the sense sensitivity and the display quality are prevented from being lowered.

The above-mentioned problem is, for example, driving a display panel including a plurality of pixel circuits each having an electro-optical element, a touch panel provided on the surface of the display panel, a display panel drive circuit for driving the display panel, and a touch panel The display panel drive circuit and the touch panel drive circuit can be solved by a display device which performs writing of a data voltage to the display panel and reading of a signal from the touch panel in different periods.

The above problem is, for example, a method of driving a display device including a display panel including a plurality of pixel circuits each having an electro-optical element and a touch panel provided on the surface of the display panel. A display device comprising a step of driving a touch panel, and a step of driving a display panel and a step of driving a touch panel performing writing of data voltage to the display panel and reading of a signal from the touch panel in different periods. It can also be solved by the driving method of.

According to the display device and the driving method thereof, by performing sensing in the display off period, it is possible to increase the S / N ratio of sensing without being affected by noise caused by display. Further, by performing display in the non-sensing period, display quality can be enhanced without being affected by noise caused by sensing. Therefore, it is possible to prevent a decrease in sense sensitivity due to noise caused by display and a decrease in display quality due to noise caused by sensing.

It is a block diagram showing composition of an organic electroluminescence display concerning an embodiment. It is a circuit diagram of the pixel circuit of the organic electroluminescence display shown in FIG. It is a figure which shows the structure of the touch panel of the organic electroluminescence display shown in FIG. It is a figure which shows the capacity | capacitance formed in the touch panel shown in FIG. It is a circuit diagram of the touch detection circuit of the organic electroluminescence display shown in FIG. It is a figure which shows the operation timing of the organic electroluminescence display shown in FIG. It is a timing chart of the organic electroluminescence display shown in FIG. It is a block diagram which shows the structure of the scanning line drive circuit of the organic electroluminescence display shown in FIG. FIG. 9 is a circuit diagram of a unit circuit of the scanning line drive circuit shown in FIG. 8. 9 is a timing chart of the scanning line drive circuit shown in FIG. FIG. 3 is a diagram showing voltage-luminance characteristics of the organic EL element in the pixel circuit shown in FIG. 2; It is sectional drawing of the organic electroluminescent panel with a touch panel.

FIG. 1 is a block diagram showing the configuration of the organic EL display device according to the embodiment. An organic EL display device 10 shown in FIG. 1 includes an organic EL panel 11, a display control circuit 12, a scanning line drive circuit 13, a data line drive circuit 14, a power supply circuit 15, a correction unit 16, a touch panel 20, and a touch panel drive circuit 30. An organic EL display device with a touch panel including the The touch panel 20 (shown by a broken line) is provided on the surface of the organic EL panel 11. In the following, m, n, M and N are integers of 2 or more, i is an integer of 1 or more and n or less, j is an integer of 1 or more and m or less, p is an integer of 1 or more and N or less, q is 1 or more and M or less It is assumed that it is an integer of

The organic EL panel 11 includes n scanning lines G1 to Gn, m data lines D1 to Dm, and (m × n) pixel circuits 17. The scan lines G1 to Gn are arranged in parallel to one another. The data lines D1 to Dm are arranged parallel to one another so as to be orthogonal to the scanning lines G1 to Gn. The scanning lines G1 to Gn and the data lines D1 to Dm intersect at (m × n) locations. The (m × n) pixel circuits 17 are arranged corresponding to the intersections of the scanning lines G1 to Gn and the data lines D1 to Dm.

The display control circuit 12 outputs control signals CS1 to CS4 to the scanning line drive circuit 13, the data line drive circuit 14, the power supply circuit 15, and the touch panel drive circuit 30, respectively. The display control circuit 12 also outputs the video signal X1 input from the outside of the organic EL display device 10 to the correction unit 16. The correction unit 16 performs correction processing (details will be described later) on the video signal X1 output from the display control circuit 12, and outputs the corrected video signal X2 to the data line drive circuit 14.

The scanning line drive circuit 13 and the data line drive circuit 14 function as a display panel drive circuit that drives the display panel (organic EL panel 11). The scanning line drive circuit 13 drives the scanning lines G1 to Gn based on the control signal CS1. The data line drive circuit 14 drives the data lines D1 to Dm based on the control signal CS2 and the corrected video signal X2. More specifically, in each line period, the scanning line drive circuit 13 selects one scanning line from the scanning lines G1 to Gn, and selects the selected scanning line (write control transistor in the pixel circuit 17). Apply a voltage that turns on). Thereby, the m pixel circuits 17 connected to the selected scanning line are selected at once. The data line drive circuit 14 applies m data voltages corresponding to the corrected video signal X2 to the data lines D1 to Dm. Thus, m data voltages are respectively written to the selected m pixel circuits. As described above, the scanning line driving circuit 13 and the data line driving circuit 14 write the data voltage to the organic EL panel 11. The scanning line drive circuit 13 is formed on the organic EL panel 11 together with the pixel circuit 17 (gate driver monolithic configuration).

An upper electrode (not shown) and a power supply wiring 18 are formed in the organic EL panel 11. The upper electrode is provided corresponding to the (m × n) pixel circuits 17 on the organic EL panel 11. The power supply circuit 15 applies the low level power supply voltage ELVSS to the upper electrode based on the control signal CS3 and applies the high level power supply voltage ELVDD to the power supply wiring 18.

The touch panel drive circuit 30 drives the touch panel 20 based on the control signal CS4. The touch panel drive circuit 30 detects a touch position on the touch panel 20 based on an output signal from the touch panel 20, and outputs a position signal PS indicating the touch position to the display control circuit 12. The touch panel drive circuit 30 reads a signal from the touch panel 20 using the touch detection circuit 31.

FIG. 2 is a circuit diagram of the pixel circuit 17 in the i-th row and the j-th column. The pixel circuit 17 includes transistors T1 and T2, a capacitor C1, and an organic EL element L1. The organic EL element L1 is an electro-optical element that emits light of any of red, green and blue. The transistors T1 and T2 are N-channel thin film transistors (Thin Film Transistors: TFTs). The transistors T1 and T2 are formed using, for example, an oxide semiconductor such as indium gallium zinc oxide (IGZO), amorphous silicon, microcrystalline silicon, low temperature polysilicon, single crystal silicon, or the like.

The drain terminal of the transistor T1 is connected to the power supply wiring 18 to which the high level power supply voltage ELVDD is applied. The source terminal of the transistor T1 is connected to the anode terminal of the organic EL element L1. The cathode terminal of the organic EL element L1 is connected to the upper electrode 19 to which the low level power supply voltage ELVSS is applied. One conduction terminal (the terminal on the left side in FIG. 2) of the transistor T2 is connected to the data line Dj. The other conduction terminal of the transistor T2 is connected to the gate terminal of the transistor T1. The gate terminal of the transistor T2 is connected to the scan line Gi. The capacitance C1 is provided between the gate terminal and the drain terminal of the transistor T1. Hereinafter, a node to which the gate terminal of the transistor T1 is connected is referred to as Na.

While the voltage of the scanning line Gi is at high level, the transistor T2 is turned on, and the voltage of the data line Dj is applied to the node Na. When the voltage of the scanning line Gi becomes low level, the transistor T2 is turned off. After the transistor T2 is turned off, the node Na is in a floating state, and the capacitor C1 holds the gate-drain voltage of the transistor T1. The drive current flowing through the transistor T1 and the organic EL element L1 changes in accordance with the gate-source voltage of the transistor T1. The organic EL element L1 emits light at a luminance corresponding to the drive current. The transistor T1 functions as a drive transistor, and the transistor T2 functions as a write control transistor.

FIG. 3 is a plan view of the touch panel 20. FIG. The touch panel 20 includes N drive lines Tx1 to TxN, M sense lines Sn1 to SnM, and an interlayer insulating film 21. Drive lines Tx1 to TxN are arranged in parallel to one another. Sense lines Sn1 to SnM are arranged parallel to one another so as to be orthogonal to drive lines Tx1 to TxM. Drive lines Tx1 to TxN and sense lines Sn1 to SnM are formed in different wiring layers with interlayer insulating film 21 interposed therebetween. The drive lines Tx1 to TxN and the sense lines Sn1 to SnM cross at (M × N) locations. As a result, (M × N) capacitors are formed on the touch panel 20.

FIG. 4 is a diagram showing a capacitance formed on the touch panel 20. As shown in FIG. In FIG. 4, the capacitance Cpq formed at the intersection of the p-th drive line Txp and the q-th sense line Snq is described. One electrode of capacitance Cpq is connected to drive line Txp, and the other electrode is connected to sense line Snq. The number M of drive lines and the number N of sense lines may be arbitrary. For example, the number M, N may be about 10 to 30.

FIG. 5 is a circuit diagram of the touch detection circuit 31 included in the touch panel drive circuit 30. The touch detection circuit 31 illustrated in FIG. 5 includes an operational amplifier 32, switches 34 and 34, and a capacitor 35. One end (the left end in FIG. 5) of the

switches

34, 34 is connected to the sense line Snq. The other end of the switch 33 is connected to the inverting input terminal of the operational amplifier 32. The low level power supply voltage VSS is applied to the other end of the switch 34 and the non-inversion input terminal of the operational amplifier 32. The capacitor 35 is provided between the inverting input terminal and the output terminal of the operational amplifier 32. The operational amplifier 32 and the capacitor 35 constitute an integrating circuit.

The touch detection circuit 31 operates as follows. During sensing, the switch 33 is controlled to be on. First, the switch 34 is controlled to be in the on state for a predetermined time. As a result, the low level power supply voltage VSS is applied to the sense line Snq. Next, a pulsed drive voltage is applied to the drive line Txp. Thereby, the initial charge is accumulated in the capacitance Cpq. The amount of initial charge Qini stored at this time is given by the following equation (1).
Qini = Cx × Vini (1)
However, in the equation (1), Cx is an initial value of the capacitance Cpq, and Vini is a difference between the drive voltage and the low level power supply voltage VSS.

When the touch unit (a finger, a pen or the like) touches the vicinity of the intersection of the drive line Txp and the sense line Snq in the touch panel 20, the charge accumulated in the capacitor Cpq moves to the touch unit (see FIG. 4). The accumulated charge decreases. Along with this, the voltage of the sense line Snq changes. The operational amplifier 32 integrates the amount of change in voltage of the sense line Snq, and outputs a signal Vout indicating the integration result. The signal Vout indicates a change in capacitance Cpq when the touch unit touches the surface of the touch panel 20.

The touch panel drive circuit 30 obtains the mapping data including the (M × N) integration results by performing the above processing on the (M × N) capacitances formed on the touch panel 20. The touch panel drive circuit 30 detects a touch position in the touch panel 20 based on the mapping data, and outputs a position signal PS indicating the touch position to the display control circuit 12.

As described above, the conventional organic EL display device with a touch panel performs display and sensing independently of each other by unique timing. On the other hand, the organic EL display device 10 synchronously performs display and sensing. The display panel drive circuit (the scanning line drive circuit 13 and the data line drive circuit 14) and the touch panel drive circuit 30 write the data voltage to the organic EL panel 11 and read the signal from the touch panel 20 in different periods. More specifically, in the organic EL display device 10, a black display period (hereinafter, referred to as a black display period) is set once in one frame period. The touch panel drive circuit 30 reads a signal from the touch panel 20 in the black display period. The display panel drive circuit writes the voltage VZ for stopping the light emission of the organic EL element to all the pixel circuits 17 in the black display period. In the organic EL display device 10, display and sensing are performed in different periods. That is, no sensing is performed during display, and no display is performed during sensing.

FIG. 6 is a view showing operation timings of the organic EL display device 10. As shown in FIG. FIG. 7 is a timing chart of the organic EL display device 10. As shown in FIGS. 6 and 7, a black display period is provided at the beginning of each frame period. In the black display period, the voltages of the scanning lines G1 to Gn are controlled to the high level, and the voltage VZ for black display is applied to the data lines D1 to Dm. Therefore, in all the pixel circuits 17, the transistor T2 is turned on, and the voltage VZ is applied to the node Na via the transistor T2. At this time, since the drive current does not flow through the transistor T1, the organic EL element L1 does not emit light. Therefore, a black screen is displayed in the black display period. The organic EL element L1 in the pixel circuit 17 in the i-th row does not emit light until the i-th line period. The black display period corresponds to the display off period, and the voltage VZ corresponds to the display off voltage.

In FIG. 7, EMi indicates the light emission period of the organic EL element L1 in the pixel circuit 17 in the i-th row. As shown in FIG. 7, the light emission period EM1 of the organic EL element L1 in the pixel circuit 17 in the i-th row is a period from the start of the i-th line period to the start of the black display period. For example, the light emission period EM1 of the organic EL element L1 in the pixel circuit 17 in the first row is a period from the start of the first line period to the start of the black display period. The light emission period EMn of the organic EL element L1 in the pixel circuit 17 in the n-th row is a period from the start of the n-th line period to the start of the black display period. The length of the light emission period EMi is different for each row of the pixel circuit 17.

FIG. 8 is a block diagram showing the configuration of the scanning line drive circuit 13. As shown in FIG. The scanning line drive circuit 13 has a configuration in which n unit circuits 41 are connected in multiple stages. Hereinafter, the unit circuit 41 in the i-th stage is referred to as SRi. The unit circuit 41 has a clock terminal CK, an all-on control terminal AON, a clear terminal CLR, a set terminal S, a reset terminal R, and an output terminal Q. Control signals CS1 output from the display control circuit 12 to the scanning line drive circuit 13 include two-phase clock signals CK1 and CK2, all-on control signal ALL_ON, clear signal CLEAR, gate start pulse GSP, and gate end pulse GEP. Is included. The scanning line drive circuit 13 outputs n output signals Q1 to Qn based on these signals. The output signals Q1 to Qn of the scanning line driving circuit 13 are applied to the scanning lines G1 to Gn, respectively.

The all-on control signal ALL_ON and the clear signal CLEAR are supplied to the all-on control terminal AON and the clear terminal CLR of the unit circuit 41 of each stage, respectively. The clock signal CK1 is supplied to the clock terminal CK of the unit circuit 41 in the odd-numbered stage. The clock signal CK2 is supplied to the clock terminal CK of the unit circuit 41 in the even-numbered stage. The gate start pulse GSP is supplied to the set terminal S of the unit circuit SR1 of the first stage. An output signal of the unit circuit 41 of the previous stage is supplied to the set terminal S of the unit circuit 41 of the second to nth stages. The gate end pulse GEP is supplied to the reset terminal R of the nth unit circuit SRn. An output signal of the unit circuit 41 of the next stage is supplied to the reset terminal R of the unit circuit 41 of the 1st to (n-1) th stages.

FIG. 9 is a circuit diagram of the unit circuit 41. As shown in FIG. Unit circuit 41 includes transistors T11 to T16. The transistors T11 to T16 are N-channel TFTs. The transistors T11 to T16 are configured using, for example, an oxide semiconductor such as IGZO, amorphous silicon, microcrystalline silicon, low-temperature polysilicon, single crystal silicon, or the like, similarly to the transistor in the pixel circuit 17.

The drain terminal and the gate terminal of the transistor T11 are connected to the set terminal S. The source terminal of the transistor T11 and the drain terminal of the transistor T15 are connected to the gate terminal of the transistor T12 (hereinafter, the node to which the gate terminal of the transistor T12 is connected is referred to as Nb). The drain terminal of the transistor T12 is connected to the clock terminal CK. The high level power supply voltage DC is applied to the drain terminal of the transistor T13. The source terminals of the transistors T12 and T13 and the drain terminals of the transistors T14 and T16 are connected to the output terminal Q. The low level power supply voltage VSS is applied to the source terminals of the transistors T14 to T16. The gate terminal of the transistor T13 is connected to the all on control terminal AON. The gate terminals of the transistors T14 and T15 are connected to the reset terminal R. The gate terminal of the transistor T16 is connected to the clear terminal CLR. A parasitic capacitance Cgd exists between the gate terminal and the drain terminal of the transistor T12, and a parasitic capacitance Cgs exists between the gate terminal and the source terminal of the transistor T12. The high level power supply voltage DC supplied to the scanning line drive circuit 13 and the low level power supply voltage VSS are generally referred to as the high level power supply voltage ELVDD supplied to the organic EL panel 11 and the low level power supply voltage ELVSS. Is different.

FIG. 10 is a timing chart of the scanning line drive circuit 13. The clock signal CK1 is a signal that goes high and low for a predetermined time. The clock signal CK2 is an inverted signal of the clock signal CK1. The all on control signal ALL_ON is at high level in the black display period. The gate start pulse GSP and the clear signal CLEAR become high level for a half cycle of the clock signal CK1 after the black display period. The gate end pulse GEP goes high for a half cycle of the clock signal CK1 before the black display period.

At the start of the black display period, the all on control signal ALL_ON changes to high level. Along with this, the transistor T13 is turned on in all the unit circuits 41, and the output signals Q1 to Qn become high level. At the end of the black display period, the all-on control signal ALL_ON changes to low level, and the clear signal CLEAR changes to high level. Along with this, in all unit circuits 41, the transistor T13 is turned off, the transistor T16 is turned on, and the output signals Q1 to Qn become low level.

Further, at the end of the black display period, the gate start pulse GSP changes to the high level. Along with this, in the unit circuit SR1 of the first stage, the transistor T11 is turned on, the voltage of the node Nb changes to the high level, and the transistor T12 is turned on. At this time, since the clock signal CK1 is at low level, the output signal Q1 is at low level.

The gate start pulse GSP changes to low level at the start of the first line period. Along with this, in the unit circuit SR1 of the first stage, the transistor T11 is turned off, and the node Nb is in a floating state. Further, at the start of the first line period, the clock signal CK1 changes to the high level. Along with this, the output signal Q1 of the unit circuit SR1 of the first stage becomes high level. At this time, due to the action of the parasitic capacitances Cgd and Cgs, the voltage of the node Nb becomes high level higher than normal high level (see SR1_Nb in FIG. 10). Therefore, the high level of the output signal Q1 becomes the same level as the high level of the clock signal CK1 without decreasing by the threshold voltage of the transistor T12.

The clock signal CK1 changes to low level at the end of the first line period. Along with this, the output signal Q1 of the unit circuit SR1 of the first stage becomes low level. In the second line period, the output signal Q2 of the unit circuit SR2 of the second stage becomes high level. The output signal Q2 of the unit circuit 41 of the second stage is input to the reset terminal R of the unit circuit 41 of the first stage. Therefore, when the output signal Q2 of the unit circuit 41 in the second stage becomes high level, the transistors T14 and T15 are turned on in the unit circuit 41 in the first stage. As the transistor T15 is turned on, the voltage of the node Nb changes to low level. As the transistor T14 is turned on, the output signal Q1 rapidly changes to the low level. As described above, in the first line period, the output signal Q1 of the unit circuit SR1 of the first stage is at the high level. Similarly, in the second to nth line periods, the output signals Q2 to Qn of the unit circuits 41 of the 2nd to nth stages are at the high level.

At the end of the nth line period, the gate end pulse GEP changes to high level. Accordingly, in the n-th unit circuit SRn, the transistors T14 and T15 turn on, the voltage of the node Nb changes to low level, and the output signal Qn changes to low level quickly. The gate end pulse GEP changes to low level at the start of the black display period. Along with this, in the n-th unit circuit SRn, the transistors T14 and T15 turn off.

Thus, scanning is performed by supplying the clock signals CK1 and CK2, all on control signal ALL_ON, the clear signal CLEAR, the gate start pulse GSP, and the gate end pulse GEP shown in FIG. 10 to the scanning line drive circuit 13. The lines G1 to Gn can be driven at the timing shown in FIG.

The correction unit 16 will be described below. As shown in FIG. 7, in the organic EL display device 10, the length of the light emission period of the organic EL element L1 differs for each row of the pixel circuits 17. The luminance of the organic EL element L1 is proportional to the length of the light emission period. For this reason, when the data lines D1 to Dm are driven using the video signal X1 supplied from the outside, the luminance of the display screen is bright at a portion corresponding to the scanning line selected first (in the drawing, in the upper part of the display screen) And become darker in the part corresponding to the scanning line selected later. Therefore, the correction unit 16 performs a correction process on the video signal X1 to compensate for the difference in luminance due to the difference in the length of the light emission period of the organic EL element L1, thereby correcting the video signal X2 after correction. Ask for

Before performing the correction process, in the inspection process of the organic EL display device 10, the voltage-luminance characteristic of the organic EL element L1 is determined by the following method. First, the voltage applied to the organic EL element L1 is switched stepwise from the minimum value to the maximum value, and the luminance of the organic EL panel 11 when each voltage is applied is measured. Based on the measurement result of luminance, voltage-luminance characteristics when the organic EL element L1 emits light continuously in one frame period are determined. Thereby, for the organic EL element L1, for example, the voltage-luminance characteristic shown in FIG. 11 is obtained. The correction unit 16 stores the obtained voltage-luminance characteristics. The voltage-luminance characteristics correspond to the characteristic data of the electro-optical element (organic EL element L1).

It is assumed that the gradation data of the pixel in the i-th row and the j-th column included in the video signal X1 is X. The correction unit 16 obtains corrected gradation data X ′ based on the gradation data X by the following method. First, the correction unit 16 obtains a voltage Vx corresponding to the gradation data X. Next, the correction unit 16 obtains the luminance Yx corresponding to the voltage Vx using the stored voltage-luminance characteristics of the organic EL element L1. Next, the correction unit 16 obtains the corrected luminance (Ki × Yx) by multiplying the luminance Yx by the coefficient Ki shown in the following expression (2).
Ki = Len_F / Len_EMi (2)
However, in equation (2), Len_F represents the length of one frame period, and Len_EMi represents the length of the light emission period EMi of the organic EL element L1 in the pixel circuit 17 in the i-th row.

Next, the correction unit 16 uses the voltage-luminance characteristics of the organic EL element L1 to obtain a corrected voltage Vx 'corresponding to the corrected luminance (Ki × Yx) (see FIG. 11). Next, the correction unit 16 obtains corrected gradation data X ′ corresponding to the corrected voltage Vx ′. As described above, the correction unit 16 performs the correction process to compensate for the difference in luminance caused by the difference in the length of the light emission period of the organic EL element L1, so that the image can be displayed with the correct luminance.

In the above description, the correction unit 16 performs the same process on gradation data of each color, but the correction unit 16 may perform different processes on the gradation data of each color for each color. . In this case, the correction unit 16 stores the characteristic data of the electro-optical element for each color, and performs the correction process using the characteristic data stored for each color. The correction unit 16 stores, for example, voltage-brightness characteristics of an organic EL element that emits red light, an organic EL element that emits green light, and an organic EL element that emits blue light. Tone data X 'after correction is obtained based on tone data X with reference to the characteristics. As a result, the correction process can be performed with higher accuracy, and the image can be displayed with more correct luminance, in consideration of the difference of the characteristic of the organic EL element due to the light emission color.

As described above, the correction unit 16 performs a correction process on the input video signal (video signal X1) to compensate for the difference in luminance due to the difference in the length of the light emission period of the organic EL element L1. The video signal X2 is output to the display panel drive circuit (data line drive circuit 14).

Hereinafter, the effects of the organic EL display device 10 according to the present embodiment will be described. As described above, in the conventional organic EL display device with a touch panel, there is a problem that the sense sensitivity is lowered by the noise caused by the display, and the display quality is lowered by the noise caused by the sensing.

On the other hand, the organic EL display device 10 performs the display and the sensing in different periods by performing the sensing in the black display period set in each frame period. In the black display period, no current flows in the organic EL element L1 in the pixel circuit 17. Therefore, in the black display period, the low level power supply voltage ELVSS applied to the upper electrode 19 hardly changes. Therefore, by performing sensing in the black display period, it is possible to increase the S / N ratio of sensing without being affected by the noise caused by the display.

In the organic EL display device, current flows from all pixel circuits to the upper electrode common to all pixel circuits during display. When a low level power supply voltage ELVSS of direct current is applied to the upper electrode, in the conventional organic EL display device with a touch panel, the voltage of the upper electrode is shaken during display (ΔELVSS), and sensing is performed during display Large noise is generated. In the organic EL display device 10, generation of noise at the time of sensing can be prevented by performing sensing in the black display period in which no current flows in the upper electrode 19.

In addition, the organic EL display device 10 does not perform sensing during display. For this reason, even if the electrode voltage (voltage of drive lines Tx1 to TxN, voltage of sense lines Sn1 to SnM) of the capacitance formed on the touch panel 20 during sensing changes due to noise, the pixel circuit 17 during display exerts an influence You will not receive Therefore, by performing the display in the non-sensing period, the display quality can be enhanced without being affected by the noise caused by the sensing.

As described above, according to the organic EL display device 10 according to the present embodiment, it is possible to prevent a decrease in sense sensitivity due to noise caused by display and a decrease in display quality due to noise caused by sensing.

In the organic EL display device 10, it is preferable that the low level power supply voltage ELVSS applied to the upper electrode 19 and the voltage applied to the drive lines Tx1 to TxN of the touch panel 20 in the black display period be at the same level. . In other words, when the display panel includes the common electrode (upper electrode 19) corresponding to the plurality of pixel circuits 17 and the touch panel 20 includes the drive lines Tx1 to TxN, the drive lines Tx1 to TxN are displayed in the display off period. Preferably, a voltage at the same level as the reference voltage applied to the Thereby, sensing can be performed more stably.

Various modifications can be made to the above embodiment. For example, in the above embodiment, the organic EL display device including the pixel circuit including the organic EL device (organic light emitting diode) has been described as an example of the display device including the pixel circuit including the electro-optical device. In the method, an inorganic EL display device including a pixel circuit including an inorganic light emitting diode, or a quantum-dot light emitting diode (QLED) display device including a pixel circuit including a quantum dot light emitting diode may be configured.

As a pixel circuit of the organic EL panel 11, any pixel circuit other than the pixel circuit 17 shown in FIG. 2 may be used. As a unit circuit of the scanning line drive circuit 13, unit circuits other than the unit circuit 41 shown in FIG. 9 may be used. The polarity of the transistor included in the pixel circuit of the organic EL panel 11 and the unit circuit of the scanning line driving circuit 13 may be an N-channel type or a P-channel type. The sensing method of the touch panel 20 may be a mutual capacitance method or a self capacitance method. The configuration of the touch panel 20 may be any of an in-cell method, an on-cell method, and an out-cell method.

The configuration of the organic EL panel 11 may be a top emission type or a bottom emission type. The organic EL panel 11 may have a stripe configuration including red, green and blue sub-pixels, and has a configuration other than a stripe configuration including red, green and blue sub-pixels And may include sub-pixels of colors other than red, green and blue. In the organic layer formation process, any method such as a vapor deposition technique or an inkjet technique may be used. In the organic layer formation process, an RGB color separation method may be used, or a color filter method may be used.

The scanning line drive circuit of the organic EL panel 11 may be disposed on one side of the organic EL panel 11 or may be disposed on both sides of the organic EL panel 11. In the latter case, two scanning line drive circuits arranged on both sides of the organic EL panel 11 may drive the scanning lines from both sides, and drive the odd-numbered scanning lines and the even-numbered scanning lines separately. May be The scanning line drive circuit may be formed on the organic EL panel 11 together with the pixel circuit 17 or may be provided outside the organic EL panel 11.

DESCRIPTION OF SYMBOLS 10 ... Organic electroluminescence display 11 ... Organic electroluminescent panel 12 ... Display control circuit 13 ... Scanning line drive circuit 14 ... Data line drive circuit 15 ... Power supply circuit 16 ... Correction | amendment part 17 ... Pixel circuit 18 ... Power supply wiring 19 ... Upper electrode 20 ... Touch panel 21 ... interlayer insulating film 30 ... touch panel drive circuit 31 ... touch detection circuit 32 ...

operational amplifier

33, 34 ... switch 35 ... capacity 41 ... unit circuit

Claims

A display panel including a plurality of pixel circuits each having an electro-optical element;
A touch panel provided on the surface of the display panel;
A display panel drive circuit for driving the display panel;
A touch panel drive circuit for driving the touch panel;
The display device, wherein the display panel drive circuit and the touch panel drive circuit perform writing of the data voltage to the display panel and reading of a signal from the touch panel in different periods.
The display device according to claim 1, wherein the touch panel drive circuit reads a signal from the touch panel in a display off period provided in a frame period.
3. The display device according to claim 2, wherein the display panel drive circuit writes a display off voltage for stopping light emission of the electro-optical element to all the pixel circuits in the display off period.
A correction process is performed on the input video signal to compensate for the difference in luminance due to the difference in the light emission period length of the electro-optical element, and the corrected video signal is output to the display panel drive circuit. The display device according to claim 3, further comprising a correction unit.
5. The display device according to claim 4, wherein the correction unit stores the characteristic data of the electro-optical element for each color, and performs the correction process using the characteristic data.
The display panel further includes a plurality of scan lines and a plurality of data lines,
4. The display panel drive circuit according to claim 3, wherein a selection voltage is applied to all the scanning lines and the display off voltage is applied to all the data lines in the display off period. Display device.
The display panel further includes a common electrode corresponding to the plurality of pixel circuits,
The touch panel includes a drive line,
The display device according to claim 3, wherein a voltage of the same level as a reference voltage applied to the drive line in the display off period is applied to the common electrode.
The display device according to any one of claims 1 to 7, wherein the electro-optical element is an organic light emitting diode.
The display device according to any one of claims 1 to 7, wherein the electro-optical element is any of an inorganic light emitting diode and a quantum dot light emitting diode.
A method of driving a display device, comprising: a display panel including a plurality of pixel circuits each having an electro-optical element; and a touch panel provided on the surface of the display panel,
Driving the display panel;
Driving the touch panel;
Driving the display device is characterized in that the step of driving the display panel and the step of driving the touch panel perform writing of the data voltage to the display panel and reading of a signal from the touch panel in different periods. Method.
The method of driving a display device according to claim 10, wherein the step of driving the touch panel reads out a signal from the touch panel in a display off period provided in a frame period.
12. The display according to claim 11, wherein the step of driving the display panel writes a display off voltage for stopping light emission of the electro-optical element to all the pixel circuits in the display off period. How to drive the device.
A correction process is performed on the input video signal to compensate for the difference in luminance due to the difference in the length of the light emission period of the electro-optical element, and the corrected video signal for the step of driving the display panel The method of driving the display device according to claim 12, further comprising the step of outputting.
The method according to claim 13, wherein in the step of performing the correction process, characteristic data of the electro-optical element is stored for each color, and the correction process is performed using the characteristic data. .
The display panel further includes a plurality of scan lines and a plurality of data lines,
13. The method according to claim 12, wherein driving the display panel applies a selection voltage to all the scanning lines and applies the display off voltage to all the data lines in the display off period. And a driving method of the display device described.
The display panel further includes a common electrode corresponding to the plurality of pixel circuits,
The touch panel includes a drive line,
The method according to claim 12, wherein a voltage of the same level as the reference voltage applied to the drive line in the display off period is applied to the common electrode.
The display device driving method according to any one of claims 10 to 16, wherein the electro-optical element is an organic light emitting diode.
The display device driving method according to any one of claims 10 to 16, wherein the electro-optical element is any of an inorganic light emitting diode and a quantum dot light emitting diode.