WO2022124165A1 - 表示装置 - Google Patents

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Publication number
WO2022124165A1
WO2022124165A1 PCT/JP2021/044153 JP2021044153W WO2022124165A1 WO 2022124165 A1 WO2022124165 A1 WO 2022124165A1 JP 2021044153 W JP2021044153 W JP 2021044153W WO 2022124165 A1 WO2022124165 A1 WO 2022124165A1
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WIPO (PCT)
Prior art keywords
voltage
transistor
display device
signal
light emitting
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Ceased
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PCT/JP2021/044153
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English (en)
French (fr)
Japanese (ja)
Inventor
尚司 豊田
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Sony Semiconductor Solutions Corp
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Sony Semiconductor Solutions Corp
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Priority to JP2022568219A priority Critical patent/JPWO2022124165A1/ja
Publication of WO2022124165A1 publication Critical patent/WO2022124165A1/ja
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/22—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
    • G09G3/30—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels
    • G09G3/32—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED]
    • G09G3/3208—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED]
    • G09G3/3225—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED] using an active matrix
    • G09G3/3233—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED] using an active matrix with pixel circuitry controlling the current through the light-emitting element
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
    • H10K59/10—OLED displays
    • H10K59/12—Active-matrix OLED [AMOLED] displays
    • H10K59/131—Interconnections, e.g. wiring lines or terminals

Definitions

  • the embodiment according to the present disclosure relates to a display device.
  • the voltage of the main power supply is being lowered for the purpose of lowering power consumption.
  • the amplitude of the signal voltage Vsig cannot be sufficiently increased, and the maximum brightness of the light emitting unit may be limited.
  • a display device capable of improving the brightness is provided.
  • the pixel array section where the pixel circuit is arranged and A drive circuit for driving the pixel array unit is provided.
  • the pixel circuit is A light emitting element that emits light with brightness according to the current flowing from the anode to the cathode, A drive transistor that drives the light emitting element based on the written signal voltage, A sampling transistor that samples the signal voltage written to the drive transistor, It has an anode voltage control unit that makes the anode voltage of the light emitting element higher than the cathode voltage of the light emitting element during the signal voltage writing period in which the sampling transistor is turned on and the signal voltage is written to the drive transistor.
  • a display device is provided.
  • the anode voltage control unit has a first switching transistor that is turned on within the signal voltage writing period to set the anode voltage of the light emitting element to a reference voltage.
  • the reference voltage may transition from the first voltage to a second voltage higher than the cathode voltage in accordance with the timing at which the sampling transistor is turned on.
  • the drive circuit may have a reference voltage control unit that controls the voltage value of the reference voltage so that the voltage value of the reference voltage becomes higher than the cathode voltage at least during the signal voltage writing period.
  • the reference voltage control unit may generate a pulse voltage whose voltage level is higher than the cathode voltage during the signal voltage writing period and output it to the reference voltage.
  • the reference voltage transitions from the first voltage to the second voltage at the timing when the sampling transistor is turned on, and then from the second voltage at the timing when the sampling transistor is turned off. It may transition to the first voltage.
  • the reference voltage transitions from the first voltage to the second voltage at the timing when the sampling transistor is turned on, and then the second voltage at the timing when the light emitting of the light emitting element is stopped. May transition to the first voltage.
  • the drive transistor, the sampling transistor, and the first switching transistor may be P-channel type transistors.
  • the drive transistor, the sampling transistor, and the first switching transistor may be N-channel type transistors.
  • the anode voltage control unit may make the anode voltage substantially the same as the cathode voltage during a predetermined period before the signal voltage writing period is started.
  • the pixel circuit may further include a second switching transistor for diode-connecting the drive transistor in a predetermined period before the signal voltage writing period is started.
  • the predetermined period may be a period in which the gate-source voltage of the drive transistor is set to a voltage corresponding to the threshold voltage of the drive transistor.
  • the light emitting element may emit light with a brightness corresponding to the current flowing through the drive transistor based on the signal voltage.
  • the display device of the present disclosure is a flat panel type display device in which a sampling transistor and a pixel circuit having a holding capacity are arranged in addition to a drive transistor for driving a light emitting unit.
  • the flat display device include an organic EL display device, a liquid crystal display device, and a plasma display device.
  • the organic EL display device uses electroluminescence of an organic material and uses an organic EL element that emits light when an electric field is applied to an organic thin film as a pixel light emitting element (electro-optical element). ing.
  • An organic EL display device that uses an organic EL element as the light emitting part of a pixel has the following features. Since the organic EL element is a self-luminous element, the organic EL display device has higher image visibility than the liquid crystal display device, which is the same flat display device, and is a lighting member such as a backlight. It is easy to reduce the weight and thickness because it does not require. Further, since the response speed of the organic EL element is as high as several microseconds, the organic EL display device does not generate an afterimage when displaying a moving image.
  • the organic EL element is a self-luminous element and a current-driven electro-optical element.
  • Examples of the current-driven electro-optical element include an inorganic EL element, an LED element, a semiconductor laser element, and the like, in addition to the organic EL element.
  • a flat display device such as an organic EL display device can be used as a display unit (display device) in various electronic devices provided with a display unit.
  • Various electronic devices include television systems, head-mounted displays, digital cameras, video cameras, game machines, notebook personal computers, mobile information devices such as electronic books, PDA (Personal Digital Assistant), mobile phones, etc.
  • a mobile communication device or the like can be exemplified.
  • the drive unit may be configured so that the gate node of the drive transistor is in a floating state and then the source node is in a floating state. Further, the drive unit may be configured to write the signal voltage by the sampling transistor while keeping the source node of the drive transistor in the floating state.
  • the initialization voltage may be supplied to the signal line at a timing different from the signal voltage, and may be written from the signal line to the gate node of the drive transistor by sampling by the sampling transistor.
  • the pixel circuit can be configured to be formed on a semiconductor such as silicon.
  • the drive transistor may be configured to consist of a P-channel type transistor. The reason why the P-channel type transistor is used as the drive transistor instead of the N-channel type transistor is as follows.
  • the transistor When a transistor is formed on a semiconductor such as silicon rather than on an insulator such as a glass substrate, the transistor is not a source / gate / drain terminal but a source / gate / drain / backgate (base). It has 4 terminals.
  • the back gate (board) voltage becomes 0 V, which adversely affects the operation of correcting the variation of the threshold voltage of the drive transistor for each pixel.
  • the variation in the characteristics of the transistor is smaller in the P-channel type transistor having no LDD region than in the N-channel type transistor having the LDD (Lightly Doped Drain) region, and the pixel miniaturization and eventually the display device. It is advantageous for achieving high definition. For this reason, when it is assumed that the transistor is formed on a semiconductor such as silicon, it is preferable to use a P-channel transistor instead of an N-channel transistor as the drive transistor.
  • the sampling transistor may also be configured to include a P-channel type transistor.
  • the pixel circuit may be configured to have a light emission control transistor for controlling light emission / non-light emission of the light emitting unit.
  • the light emission control transistor may also be configured to consist of a P-channel type transistor.
  • the holding capacity may be configured to be connected between the gate node and the source node of the drive transistor.
  • the pixel circuit can be configured to have an auxiliary capacitance connected between the source node of the drive transistor and the node of the fixed potential.
  • the pixel circuit may have a configuration having a switching transistor connected between the drain node of the drive transistor and the anode node of the light emitting unit.
  • the switching transistor may also be configured to consist of a P-channel type transistor.
  • the drive unit may be configured to have the switching transistor in a conductive state during the non-light emission period of the light emitting unit.
  • the drive unit activates the signal for driving the switching transistor before the sampling timing of the initialization voltage by the sampling transistor. Then, the signal for driving the light emission control transistor can be activated and then inactive. At this time, the drive unit may be configured to complete the sampling of the initialization voltage by the sampling transistor before the signal for driving the light emission control transistor is inactive.
  • FIG. 1 is an explanatory diagram showing an example of the configuration of the display device 100 according to the first embodiment of the present disclosure.
  • FIG. 1 is an explanatory diagram showing an example of the configuration of the display device 100 according to the first embodiment of the present disclosure.
  • an example of the configuration of the display device 100 according to the first embodiment of the present disclosure will be described with reference to FIG.
  • the pixel unit 110 has a configuration in which pixels provided with organic EL elements and other self-luminous elements are arranged in a matrix.
  • the pixel unit 110 is provided with scanning lines in the horizontal direction in line units with respect to the pixels arranged in a matrix, and signal lines SL are provided for each row so as to be orthogonal to the scanning lines.
  • the horizontal selector 120 sequentially transfers a predetermined sampling pulse, and sequentially latches the image data with this sampling pulse, thereby distributing the image data to each signal line SL. Further, the horizontal selector 120 performs analog digital conversion processing on the image data distributed to each signal line SL, thereby generating a drive signal indicating the emission luminance of each pixel connected to each signal line SL by time division. The horizontal selector 120 outputs this drive signal to the corresponding signal line SL.
  • the vertical scanner 130 responds to the driving of the signal line SL by the horizontal selector 120, generates a driving signal for each pixel, and outputs the driving signal to the scanning line SCN.
  • the display device 100 sequentially drives each pixel arranged in the pixel unit 110 by the vertical scanner 130, causes each pixel to emit light at the signal level of each signal line SL set by the horizontal selector 120, and produces a desired image. It is displayed by the pixel unit 110.
  • FIG. 2 is an explanatory diagram showing an example of a more detailed configuration of the display device 100 according to the first embodiment of the present disclosure.
  • FIG. 2 is an explanatory diagram showing an example of a more detailed configuration of the display device 100 according to the first embodiment of the present disclosure.
  • an example of the configuration of the display device 100 according to the first embodiment of the present disclosure will be described with reference to FIG.
  • a pixel 111R displaying red, a pixel 111G displaying green, and a pixel 111B displaying blue are arranged in a matrix.
  • the vertical scanner 130 includes an auto-zero scanner 131, a drive scanner 132, and a write scanner 133. By supplying a signal from each scanner to the pixels arranged in a matrix in the pixel unit 110, the TFTs provided in the respective pixels are turned on and off.
  • the vertical scanner 130 further has a VSS2 scanner (reference voltage control unit) 134.
  • the VSS2 scanner 134 generates, for example, a control voltage signal and supplies the control voltage signal to the pixels arranged in a matrix in the pixel unit 110. More specifically, the VSS2 scanner 134 supplies the control voltage signal to the feeder line of the reference voltage. That is, the VSS2 scanner 134 outputs a control voltage signal in the same manner as the signal outputs of the auto zero scanner 131, the drive scanner 132, and the write scanner 133.
  • the anode potential (anode voltage) of the organic EL element is controlled when the signal voltage Vsig is written, as will be described later. Can be done. As a result, the emission brightness of the organic EL element EL can be improved.
  • FIG. 3 is an explanatory diagram showing an example of a more detailed configuration of the display device 100 according to the first embodiment of the present disclosure.
  • FIG. 3 is an explanatory diagram showing an example of a more detailed configuration of the display device 100 according to the first embodiment of the present disclosure.
  • an example of the configuration of the display device 100 according to the first embodiment of the present disclosure will be described with reference to FIG.
  • FIG. 3 illustrates a pixel circuit for one pixel arranged in a matrix in the pixel unit 110.
  • the pixel circuit includes transistors T1 to T3, an anode potential control unit (anode voltage control unit) 112, capacitors C1 and C2, and an organic EL element EL.
  • the anode potential control unit 112 includes, for example, the transistor T4.
  • FIG. 4 is an explanatory diagram showing the pixel circuit shown in FIG. 3 extracted.
  • Transistor T1 is a light emission control transistor that controls light emission of the organic EL element EL.
  • the transistor T1 is connected between the power supply node of the power supply voltage VCCP and the source node (source electrode) of the transistor T2, and is driven by a light emission control signal (signal DS) output from the drive scanner 132, and is an organic EL. Controls the light emission / non-light emission of the element EL.
  • the transistor T2 is a drive transistor that drives the organic EL element EL by passing a drive current corresponding to the holding voltage of the capacitor C2 through the organic EL element EL.
  • the transistor T2 is connected between the anode of the organic EL element EL and the power supply node of the power supply voltage VCCP, and controls the current flowing through the organic EL element EL based on the signal voltage Vsig. Further, the organic EL element EL emits light with brightness corresponding to the current flowing from the anode to the cathode. More specifically, the organic EL element EL emits light with a brightness corresponding to the current flowing through the transistor T2 based on the signal voltage Vsig. As shown in FIG. 4, the transistor T2 has a parasitic capacitance Cp between the gate and the drain.
  • the transistor T3 is a sampling transistor that writes the signal voltage Vsig to the gate node (gate electrode) of the transistor T2 by sampling the signal voltage Vsig under the drive by the drive signal (signal WS) supplied from the write scanner 133. be.
  • the transistor T3 is connected between the gate of the transistor T2 and the signal line SL.
  • the transistor T4 is a first switching transistor connected between the drain node (drain electrode) of the transistor T2 and the current discharge destination node (for example, the power supply VSS2).
  • the transistor T4 is controlled so that the organic EL element EL does not emit light during the non-emission period of the organic EL element EL under the drive by the drive signal (signal AZ) from the auto-zero scanner 131.
  • the control voltage generated by the VSS2 scanner 134 is supplied to the feeder line of the power supply VSS2.
  • the transistors T1 to T4 can all be configured to be composed of P-channel type transistors.
  • the capacitor C2 is connected between the gate node and the source node of the transistor T2, and holds the signal voltage Vsig written by sampling by the transistor T3.
  • the capacitor C1 is connected between the source node of the transistor T2 and the node of a fixed potential (for example, the power supply node of the power supply voltage VCCP).
  • the capacitor C1 suppresses the fluctuation of the source voltage of the transistor T2 when the signal voltage Vsig is written, and also acts to change the gate-source voltage Vgs of the transistor T2 to the threshold voltage Vth of the transistor T2.
  • a pixel portion 110, a horizontal selector 120, a vertical scanner 130, and the like are collectively formed on a transparent insulating substrate made of a glass substrate or the like using a polysilicon TFT.
  • Polysilicon TFTs cannot avoid variations in threshold voltage or mobility, and in display devices using organic EL elements, there is a problem that image quality deteriorates due to these variations.
  • the anode potential control unit 112 having the transistor T4 makes the anode potential Band of the organic EL element EL substantially the same as the cathode potential Vcat in a predetermined period before the signal voltage writing period is started.
  • the predetermined period is a period for correcting variations in the threshold voltage and mobility of the drive transistor.
  • the anode potential control unit 112 sets the anode potential Vand of the organic EL element EL higher than the cathode potential Vcat of the organic EL element EL during the signal voltage writing period in which the transistor T3 is turned on and the signal voltage Vsig is written to the transistor T2. do.
  • the transistor T4 is turned on, for example, within the signal voltage writing period, and the anode potential Band of the organic EL element EL is set to the power supply VSS2.
  • the VSS2 scanner 134 controls the voltage value of the power supply VSS2 so that the voltage value of the power supply VSS2 becomes higher than the cathode potential Vcat at least during the signal voltage writing period. As a result, as described with reference to FIG. 5, the emission brightness of the organic EL element EL can be improved.
  • the correction of the characteristic variation of the driving transistor and the operation of writing the signal voltage Vsig will be described.
  • the operation of changing the voltage value of the power supply VSS2 by the VSS2 scanner 134 will also be described.
  • FIG. 5 is an explanatory diagram showing an example of a driving method of the display device 100 according to the first embodiment of the present disclosure.
  • FIG. 5 shows the temporal transition of the source potential Vs, the gate potential Vg and the drain potential Vd of the transistor T2, and the anode potential Vand and the cathode potential (cathode voltage) Vcat of the organic EL element EL.
  • the anode potential Vand is substantially the same as the drain potential Vd.
  • FIG. 5 also shows the temporal transition of the control signal voltage supplied from the VSS2 scanner 134 to the power supply VSS2, the signal DS from the drive scanner 132, the signal WS from the write scanner 133, and the signal AZ from the auto-zero scanner 131. Has been done.
  • time t1 is, for example, the timing at which the quenching period ends and the writing period of one horizontal line (1H) begins.
  • the signal AZ is low and the transistor T4 is on. This is to prevent the organic EL element EL from emitting light due to a current flowing into the organic EL element EL during the Vth correction period described later.
  • the transistors T1 and T3 are turned on by changing the signals WS and DS from high to low.
  • the preparation period for correcting the threshold voltage Vth of the transistor T2 is entered.
  • the gate potential Vg of the transistor T2 drops to the offset voltage Vofs.
  • the transistor T3 is turned off when the signal WS changes from low to high.
  • the transistor T1 is turned off when the signal DS changes from low to high.
  • the Vth correction period is entered.
  • the gate-source voltage Vgs of the transistor T2 is set to the threshold voltage Vth.
  • the transistor T3 is turned on by changing the signal WS from high to low.
  • the writing period of the signal voltage Vsig to the transistor T2 is set.
  • the gate potential Vg of the transistor T2 becomes Vsig.
  • the voltage value of the power supply VSS2 becomes large. More specifically, the voltage value of the power supply VSS2 before the time t5 is substantially the same as, for example, the cathode potential Vcat. Therefore, it is possible to suppress the flow of unnecessary current during the Vth correction period or the like.
  • the voltage value of the power supply VSS2 becomes larger than, for example, the cathode potential Vcat. As a result, the drain potential Vd increases via the transistor T4 in the on state.
  • the VSS2 scanner 134 generates, for example, a pulse voltage whose voltage level increases during the period from time t5 to time t7 as a control voltage signal, and outputs the pulse voltage to the power supply VSS2 for each horizontal line (1H).
  • the voltage value of the power supply VSS2 transitions from the first voltage to the second voltage higher than the cathode potential Vcat at the timing when the transistor T3 is turned on.
  • the transistor T3 is turned off when the signal WS changes from low to high.
  • the writing period of the signal voltage Vsig to the transistor T2 ends.
  • the transistor T4 is turned off when the signal AZ changes from low to high between the time t6 and the time t7.
  • the transistor T1 is turned on by changing the signal DS from high to low.
  • the organic EL element EL emits light.
  • the source potential Vs of the transistor T2 becomes the power supply voltage VCCP.
  • the voltage value of the power supply VSS2 becomes smaller.
  • the voltage value of the power supply VSS2 at time t7 is a voltage value before time t5, and is substantially the same as, for example, the cathode potential Vcat. That is, the voltage value of the power supply VSS2 transitions from the second voltage to the first voltage at time t7.
  • the period from time t8 to time t9 is a light emission transition period.
  • a current flows through the organic EL element EL, and the potential difference Vold between the anode potential Vand and the cathode potential Vcat gradually widens due to the IV characteristics of the organic EL element EL. Since the cathode potential Vcat is fixed, the anode potential Vand and the drain potential Vd substantially the same as the anode potential Vd gradually increase. After that, at time t9, the drain potential Vd stabilizes.
  • the gate potential Vg also increases as the drain potential Vd increases from time t8 to time t9.
  • the source potential Vs is fixed to the power supply voltage VCCP. Therefore, from time t8 to time t9, the gate-source voltage Vgs is gradually compressed.
  • the gate potential Vg is set to the signal voltage Vsig. Therefore, even if the drain potential Vd rises due to the increase in the voltage value of the power supply VSS2, the influence on the gate potential Vg via the parasitic capacitance Cp is small.
  • the drain potential Vd can be increased by increasing the voltage value of the power supply VSS2 during the writing period of the signal voltage Vsig from the time t5 to the time t6.
  • the compression amount of the gate-source voltage Vgs in the period from the time t8 to the time t9 can be suppressed. That is, the gate-source voltage Vgs at the time of light emission after the time t9 can be increased, and the current flowing through the transistor T2 can be increased.
  • the emission brightness of the organic EL element EL can be improved.
  • FIG. 6 is an explanatory diagram showing an example of a more detailed configuration of the display device 100 according to the comparative example of the present disclosure.
  • the comparative example is different from the first embodiment in that the VSS2 scanner 134 is not provided and the fixed voltage power supply VSS is connected to the drain of the transistor T4 instead of the power supply VSS2 having a variable voltage value. ing.
  • FIG. 7 is an explanatory diagram showing an example of a driving method of the display device 100 according to the comparative example of the present disclosure.
  • the voltage value of the power supply VSS is substantially constant (DC (Direct Current)). Therefore, the drain potential Vd is substantially constant during the writing period of the signal voltage Vsig from the time t5 to the time t6.
  • the voltage value of the power supply VSS is, for example, substantially the same as the cathode potential Vcat of the organic EL element EL.
  • the drain potential Vd shown in FIG. 7 of the comparative example is smaller than the drain potential Vd shown in FIG. 5 of the first embodiment in which the voltage value of the power supply VSS2 fluctuates (AC (Alternating Current)). Therefore, in the period from time t8 to time t9, the increase value of the drain potential Vd in the comparative example is larger than the increase value of the drain potential Vd in the first embodiment. That is, in the comparative example, the increase value of the gate potential Vg via the parasitic capacitance Cp is large, and the compression amount of the gate-source voltage Vgs is large. As a result, at time t9, the gate-source voltage Vgs shown in FIG. 7 of the comparative example is smaller than the gate-source voltage Vgs shown in FIG. 5 of the first embodiment.
  • the voltage of the main power supply has been reduced for the purpose of reducing power consumption.
  • the amplitude of the signal voltage Vsig cannot be sufficiently increased, and the maximum brightness may be limited.
  • the parasitic capacitance Cp compresses the gate-source voltage Vgs at the time of light emission at time t9. The smaller the amplitude of the signal voltage Vsig, the greater the effect of compression of the gate-source voltage Vgs. As a result, the maximum brightness may be further limited.
  • the amount of increase in the anode potential Vand due to the parasitic capacitance Cp during the light emission transition period is suppressed. can do. That is, it is possible to suppress the amount of compression of the gate-source voltage Vgs due to the parasitic capacitance Cp during the light emission transition period.
  • the gate-source voltage Vgs at the time of light emission can be increased, and the light emission brightness can be improved.
  • the emission brightness can be improved without increasing the amplitude of the signal voltage Vsig. That is, it is possible to suppress the limitation of the maximum luminance due to the small amplitude of the signal voltage Vsig.
  • FIG. 8 is an explanatory diagram showing a first modification of the driving method of the display device 100 according to the first embodiment of the present disclosure.
  • the first modification is different from the first embodiment in that the timing at which the voltage value of the power supply VSS2 becomes small is before the time t7.
  • the voltage value of the power supply VSS2 becomes smaller at time t6, and becomes substantially the same as, for example, the cathode potential Vcat. Therefore, the width of the pulse voltage of the power supply VSS2 is the period from the time t5 to the time t6.
  • the width of the pulse voltage of the power supply VSS corresponds to, for example, the period during which the signal WS becomes low due to the writing of the signal voltage Vsig. That is, the voltage value of the power supply VSS2 transitions from the first voltage to the second voltage according to the timing when the transistor T3 is turned on, and then from the second voltage to the first voltage according to the timing when the transistor T3 is turned off. Transition to the voltage of.
  • the voltage value of the power supply VSS2 is preferably larger than the cathode potential Vcat, at least during the period when the signal WS is low.
  • FIG. 9 is an explanatory diagram showing a second modification of the driving method of the display device 100 according to the first embodiment of the present disclosure.
  • the second modification is different from the first embodiment in that the timing at which the voltage value of the power supply VSS2 becomes small is after the time t7.
  • the voltage value of the power supply VSS2 becomes smaller at time t10, and becomes substantially the same as, for example, the cathode potential Vcat.
  • Time t10 is the timing at which the light emission period ends and the quenching period begins. That is, the voltage value of the power supply VSS2 transitions from the first voltage to the second voltage according to the timing when the transistor T3 is turned on, and then the second voltage is matched with the timing when the light emission of the organic EL element EL is stopped. The transition from the voltage to the first voltage.
  • the timing at which the voltage value of the power supply VSS2 becomes small is not limited to the solid line shown in FIG. 9, and may be within the period from time t9 to time t10, for example, as shown by the broken line.
  • the timing at which the voltage value of the power supply VSS2 decreases is, for example, any of the time t6 from the time when the signal WS becomes high to t10 which is the start of the quenching period.
  • the timing is fine.
  • FIG. 10 is an explanatory diagram showing an example of the configuration of the pixel circuit according to the second embodiment of the present disclosure.
  • the pixel circuit has a so-called "4Tr1C" configuration as compared with FIG.
  • the capacitor C1 is not provided.
  • the transistors T1 to T4 shown in FIG. 11 are N-channel type transistors.
  • the voltage value of the power supply VSS2 becomes higher than the cathode potential Vcat during the writing period of the signal voltage Vsig. Therefore, the emission brightness can be improved as in the first embodiment.
  • FIG. 11 is an explanatory diagram showing an example of the configuration of the pixel circuit according to the third embodiment of the present disclosure.
  • the pixel circuit has a so-called “5Tr” configuration as compared with FIG.
  • the capacitor C1 is not provided.
  • the transistor T1 which is a light emission control transistor is connected not between the power supply voltage VCCP and the source of the transistor T2 but between the drain of the transistor T2 and the anode of the organic EL element EL.
  • the pixel circuit further has a transistor T5.
  • the transistor T5 is connected between the drain and the gate of the transistor T2.
  • the transistor T5 is a threshold value compensating transistor that compensates for the threshold value of the transistor T2.
  • the transistor T5 is turned on in a predetermined period before the write period of the signal voltage Vsig. That is, the transistor T5 is a second switching transistor in which the gate and drain of the transistor T2 are connected and the transistor T2 is connected by a diode during the compensation period for compensating the threshold value of the transistor T2.
  • the capacitor C2 holds the threshold voltage of the transistor T2.
  • the voltage value of the power supply VSS2 becomes higher than the cathode potential Vcat during the writing period of the signal voltage Vsig. Therefore, the emission brightness can be improved as in the first embodiment.
  • FIG. 12 is an explanatory diagram showing an example of the configuration of the pixel circuit according to the fourth embodiment of the present disclosure.
  • the pixel circuit has a so-called "6Tr" configuration as compared with FIG.
  • the fourth embodiment shown in FIG. 12 is also a modification of the third embodiment shown in FIG.
  • the signal line SL shown in FIG. 12 has a signal line SL1 and a plurality of signal lines SL2 as compared with FIG. Further, the pixel circuit further includes a transistor T6 and capacitors C3 and C4.
  • a plurality of signal lines SL2 are provided for one signal line SL1.
  • Each of the plurality of signal lines SL2 is electrically connected to the signal line SL1.
  • Each of the plurality of signal lines SL2 is electrically connected to the plurality of pixels 111. That is, one signal line SL1 is shared by a plurality of signal lines SL2, and one signal line SL2 is shared by a plurality of pixels 111. Thereby, the signal line SL2 can be made shorter than the signal line when connected to all the pixels 111.
  • the compensation operation for compensating for the threshold value of the transistor T2 the time required for charging or discharging the parasitic capacitance of the signal line SL2 can be shortened. Therefore, in the fourth embodiment, the compensation period for compensating the threshold value of the transistor T2 can be shortened as compared with the third embodiment.
  • a plurality of transistors T6 are provided for each signal line SL2 corresponding to the signal line SL2.
  • the plurality of transistors T6 are connected between the signal line SL1 and each of the plurality of signal lines SL2.
  • the transistor T6 is a switching transistor that controls the connection between the signal line SL1 and the signal line SL2.
  • a plurality of capacitors C3 are provided for each signal line SL2 corresponding to the signal line SL2.
  • the plurality of capacitors C3 are connected between the signal line SL1 and each of the plurality of signal lines SL2.
  • the capacitor C4 is connected between the signal line SL1 and the power supply VSS2.
  • the capacitor C4 holds the potential of the signal line SL1.
  • the capacitor C4 is formed, for example, by a parasitic capacitance between a signal line SL1 adjacent to each other and a feeder line of the power supply VSS2.
  • the voltage value of the power supply VSS2 becomes higher than the cathode potential Vcat during the writing period of the signal voltage Vsig. Therefore, the emission brightness can be improved as in the first embodiment.
  • the present technology can have the following configurations.
  • a pixel array unit in which a pixel circuit is arranged and A drive circuit for driving the pixel array unit is provided.
  • the pixel circuit is A light emitting element that emits light with brightness according to the current flowing from the anode to the cathode, A drive transistor that drives the light emitting element based on the written signal voltage, A sampling transistor that samples the signal voltage written to the drive transistor, It has an anode voltage control unit that makes the anode voltage of the light emitting element higher than the cathode voltage of the light emitting element during the signal voltage writing period in which the sampling transistor is turned on and the signal voltage is written to the drive transistor. , Display device.
  • the anode voltage control unit has a first switching transistor that is turned on within the signal voltage writing period to set the anode voltage of the light emitting element to the reference voltage.
  • the drive circuit has a reference voltage control unit that controls the voltage value of the reference voltage so that the voltage value of the reference voltage becomes higher than the cathode voltage at least during the signal voltage writing period (2). ).
  • the display device (4) The display device according to (3), wherein the reference voltage control unit generates a pulse voltage whose voltage level is higher than the cathode voltage during the signal voltage writing period and outputs the pulse voltage to the reference voltage.
  • the reference voltage transitions from the first voltage to the second voltage at the timing when the sampling transistor is turned on, and then at the timing when the sampling transistor is turned off, the second voltage.
  • the display device according to any one of (2) to (4), which transitions from a voltage to the first voltage.
  • the reference voltage transitions from the first voltage to the second voltage at the timing when the sampling transistor is turned on, and then at the timing when the light emitting of the light emitting element is stopped, the first voltage.
  • the display device according to any one of (2) to (4), which transitions from the voltage of 2 to the first voltage.
  • the anode voltage control unit makes the anode voltage substantially the same as the cathode voltage during a predetermined period before the signal voltage writing period is started, any one of (1) to (8).
  • the pixel circuit further includes a second switching transistor for diode-connecting the drive transistor in a predetermined period before the signal voltage writing period is started.
  • the predetermined period is a period in which the gate-source voltage of the drive transistor is set to a voltage corresponding to the threshold voltage of the drive transistor.
  • the light emitting element emits light with brightness corresponding to the current flowing through the drive transistor based on the signal voltage.
  • 100 display device 110 pixel unit, 111R pixel, 111G pixel, 111B pixel, 112 anode potential control unit, 120 horizontal selector, 130 vertical scanner, 134 VSS2 scanner, EL organic EL element, SL signal line, T1 to T6 transistor, Band Anode potential, Vcat cathode potential, Vsig signal voltage

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  • Computer Hardware Design (AREA)
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  • Control Of El Displays (AREA)
  • Control Of Indicators Other Than Cathode Ray Tubes (AREA)
PCT/JP2021/044153 2020-12-10 2021-12-01 表示装置 Ceased WO2022124165A1 (ja)

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2018200441A (ja) * 2017-05-29 2018-12-20 キヤノン株式会社 発光装置及び撮像装置
JP2019082548A (ja) * 2017-10-30 2019-05-30 ソニーセミコンダクタソリューションズ株式会社 画素回路、表示装置、画素回路の駆動方法および電子機器

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CN111710299B (zh) * 2020-06-30 2022-01-07 厦门天马微电子有限公司 一种显示面板、其驱动方法及显示装置

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2018200441A (ja) * 2017-05-29 2018-12-20 キヤノン株式会社 発光装置及び撮像装置
JP2019082548A (ja) * 2017-10-30 2019-05-30 ソニーセミコンダクタソリューションズ株式会社 画素回路、表示装置、画素回路の駆動方法および電子機器

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