JP2011022364A - Display device and drive control method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform the aging operation of a light emitting element without causing the shift of a threshold voltage of a drive transistor. <P>SOLUTION: The display device includes an active matrix substrate where many pixel circuits are arrayed each of which is provided with a light emitting element 11a, an N type driving transistor 11b, a capacitive element 11c, a selection transistor 11d, and a source transistor 11e. The aging operation of the light emitting element 11a is performed by supplying a current to the light emitting element 11a via a reset voltage line 18 and the source terminal S of the driving transistor 11b. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a display device including a light emitting element driven by an active matrix method and a drive control method for the display device.

  Conventionally, display devices using light-emitting elements such as organic EL light-emitting elements have been proposed, and their use in various fields such as displays for televisions and mobile phones has been proposed.

  In general, an organic EL light emitting element is a current driven light emitting element, and unlike a liquid crystal display, a selection transistor for selecting a pixel circuit as a driving circuit, a capacitive element for holding a charge corresponding to a display image, and organic EL light emission A driving transistor for driving the element is at a minimum (see, for example, Patent Document 1 and Patent Document 2).

  Conventionally, a thin film transistor made of low-temperature polysilicon or amorphous silicon has been used in a pixel circuit of an active matrix organic EL display device.

  However, a low-temperature polysilicon thin film transistor can obtain high mobility and threshold voltage stability, but has a problem in uniformity of mobility. Amorphous silicon thin film transistors can achieve mobility uniformity, but have problems of low mobility and threshold voltage variation over time. In addition, the inorganic oxide thin film transistor, which has been actively researched in recent years, also has a problem of variation with time of the threshold voltage.

  The non-uniformity of mobility and the instability of the threshold voltage as described above appear as unevenness in the display image. Therefore, for example, in the organic EL display device described in Patent Document 3, a method has been proposed in which the parasitic capacitance of the organic EL light-emitting element is self-charged by the driving transistor to correct the variation in the threshold voltage Vth of the driving transistor. . In the method described in Patent Document 3, a fixed voltage is applied to the gate terminal of the driving transistor, and the parasitic potential of the organic EL light-emitting element is charged with the driving current Id of the driving transistor, thereby reducing the source potential of the driving transistor. After fixing to Vg (gate voltage) −Vth (threshold voltage), a voltage program is performed in which the threshold voltage is corrected by stepping up the voltage applied to the gate terminal by the drive voltage Vod.

  Moreover, in an organic EL display device, an organic EL light emitting element using an organic material is used. However, this organic EL light emitting element has a problem of a decrease in light emission amount due to deterioration over time. The emission luminance reduction characteristic due to aging deterioration of the organic EL light emitting element does not have a simple proportional relationship with the total charge injection amount into the organic EL light emitting element, and the emission luminance is greatly reduced in the initial stage. It is a feature.

  Therefore, in order to suppress the influence of a decrease in the amount of light emission due to aging deterioration, it is proposed to perform an aging operation that stabilizes the light emission characteristics after shipment by effectively performing initial deterioration before shipment of the product. . For example, Patent Document 3 proposes a method of performing an aging operation by causing a driving current to flow through an organic EL light emitting element using a driving transistor in accordance with the luminance degradation characteristics of each of R, G, and B organic EL light emitting elements. ing. In Patent Document 4, as shown in FIG. 12, a pulse signal is output from the lighting / extinguishing control circuit, the switching transistor SWT is pulse-driven to drive the driving transistor T, and the light-emitting element D is pulsed. A method of flowing a drive current has been proposed.

JP-A-8-234683 JP 2003-173154 A JP 2003-271095 A JP 2003-323979 A JP 2006-195030 A

  Here, FIG. 13 shows a configuration of a pixel circuit described in Patent Document 3. The pixel circuit described in Patent Document 3 includes a light emitting element including a light emitting unit 1 and a parasitic capacitance 2 thereof, a driving transistor 3 that allows a driving current to flow through the light emitting element, and a gate terminal G and a source terminal S of the driving transistor 3. , A selection transistor 5 connected to the gate terminal G of the driving transistor 3, and a source connection switch 6 connected to the source terminal S of the driving transistor 3. Yes.

  In the threshold voltage detection operation in the pixel circuit described in Patent Document 3, specifically, the gate terminal G of the driving transistor 3 is turned on with the selection transistor 5 turned on and the source connection switch 6 turned off. A fixed voltage is applied, and a driving current flows through the driving transistor 3 by applying the fixed voltage, and the parasitic capacitance 2 of the light emitting element is charged by the driving current.

  As the parasitic capacitance 2 is charged, the source voltage Vs at the source terminal S of the driving transistor 3 increases. Since VB supplied to the gate terminal G of the driving transistor 3 is a fixed voltage, when the source voltage Vs increases, the gate-source voltage Vgs of the driving transistor 3 decreases, and Vgs = threshold voltage Vth. Thus, the driving current Id of the driving transistor 3 becomes 0, and the increase in the source voltage Vs stops. As a result, the threshold voltage Vth of the driving transistor 3 is held in the capacitive element 4.

  Here, it is necessary to prevent the light emitting element from emitting light during the threshold voltage detection operation as described above, and the source voltage Vs of the source terminal S of the driving transistor 3 needs to be maintained below the light emission threshold voltage of the light emitting element. is there.

  As described above, during the threshold voltage detection operation, the source voltage Vs of the driving transistor 3 rises until Vgs = Vth. That is, the source voltage Vs of the driving transistor 3 changes according to the magnitude of Vth of the driving transistor 3.

  That is, in order to effectively execute the threshold voltage detection operation and realize display with excellent luminance uniformity, the source voltage Vs of the driving transistor 3 corresponding to the magnitude of Vth including temporal variation is used as the light emitting element. It is necessary to maintain it below the light emission threshold voltage.

  However, since the aging operations described in Patent Document 3 and Patent Document 4 are performed by flowing a driving current of a driving transistor having a magnitude sufficient for initial degradation to the light emitting element, the Vth of the driving transistor is shifted. End up.

  This suppresses the variation with time of the light emitting element by the aging operation, thereby narrowing the allowable range of the Vth shift of the driving transistor, and as a result, shortening the duration of the display luminance uniformity performance. It will be.

  In view of the above circumstances, an object of the present invention is to provide a display device capable of performing an aging operation of a light emitting element without causing a shift in threshold voltage of a driving transistor, and a drive control method for the display device. And

  According to the display device driving control method of the present invention, a light emitting element, an N-type driving transistor in which a source terminal is connected to an anode terminal of the light emitting element, and a driving current is supplied to the light emitting element, a gate terminal and a source terminal of the driving transistor, And a selection transistor connected between a gate terminal of the driving transistor and a signal line for supplying a driving voltage to the gate terminal of the driving transistor, and a source terminal of the driving transistor and driving In a drive control method for a display device including an active matrix substrate in which a plurality of pixel circuits each having a source transistor connected between a reset voltage line for supplying a reset voltage to a source terminal of the transistor for use is arranged, the reset voltage line And by passing a current through the light emitting element through the source terminal of the driving transistor. And performing an aging operation of the optical element.

  In the display device drive control method of the present invention, the threshold voltage detection operation of the drive transistor can be performed by charging the parasitic capacitance of the light emitting element with the drive current of the drive transistor.

  In addition, during the aging operation of the light emitting element, the selection transistor and the source transistor can be turned on to supply the same aging operation voltage to the signal line and the reset voltage line.

  In the display device of the present invention, a source terminal is connected to a light emitting element, an anode terminal of the light emitting element, and an N-type driving transistor that supplies a driving current to the light emitting element, and a gate terminal and a source terminal of the driving transistor are connected. And a selection transistor connected between a gate terminal of the driving transistor and a signal line for supplying a driving voltage to the gate terminal of the driving transistor, and a source terminal of the driving transistor and a source of the driving transistor In a display device including an active matrix substrate in which a large number of pixel circuits each having a source transistor connected between a reset voltage line for supplying a reset voltage to a terminal are arranged, the reset voltage line and the source terminal of the driving transistor are arranged The aging operation of the light emitting element is performed by passing a current through the light emitting element through Characterized by comprising a control unit for controlling so.

  In the display device of the present invention, the control unit may be controlled to perform the threshold voltage detection operation of the driving transistor by charging the parasitic capacitance of the light emitting element with the driving current of the driving transistor. it can.

  In addition, the control unit controls to turn on the selection transistor and the source transistor and supply the same aging operation voltage to the signal line and the reset voltage line during the aging operation of the light emitting element. be able to.

  In addition, a thin film transistor having a negative threshold voltage is used as the driving transistor, and the control unit controls the aging operation voltage with respect to the power supply voltage line connected to the drain terminal of the driving transistor during the aging operation of the light emitting element. Can be controlled to supply.

  In addition, the active matrix substrate includes a large number of signal lines and a large number of reset voltage lines, and the control unit sequentially switches some of the reset voltage lines among the large number of reset voltage lines to reset the partial matrix. The voltage for aging operation is sequentially supplied to the voltage line, and the reset voltage line and / or the signal line connected to the pixel circuit to which the aging operation voltage is not supplied is more than the light emission threshold voltage of the light emitting element of the pixel circuit. It can be controlled to supply a low voltage.

  Here, the “aging operation” refers to an operation of initially degrading the light emitting element by passing a current through the light emitting element in advance.

  According to the display device and the drive control method thereof of the present invention, the aging operation of the light emitting element is performed by flowing a current to the light emitting element through the reset voltage line and the source terminal of the driving transistor. An aging operation can be performed without causing a shift of the threshold voltage, and a display device that can maintain display luminance uniformity for a long period of time can be realized.

1 is a schematic configuration diagram of an organic EL display device to which a first embodiment of a display device of the present invention is applied. The figure which shows the structure of the pixel circuit of the organic electroluminescence display to which 1st Embodiment of the display apparatus of this invention is applied. The figure for demonstrating the effect | action of the aging operation | movement of the organic electroluminescence display to which the 1st Embodiment of this invention is applied. Timing chart for explaining the operation of the display operation of the organic EL display device to which the first embodiment of the display device of the present invention is applied The figure for demonstrating the effect | action of the reset operation | movement of the organic electroluminescence display to which 1st Embodiment of the display apparatus of this invention is applied. The figure for demonstrating the effect | action of the threshold voltage detection operation | movement of the organic electroluminescent display apparatus to which 1st Embodiment of the display apparatus of this invention is applied. The figure for demonstrating the effect | action of the program operation | movement of the organic electroluminescent display apparatus to which 1st Embodiment of the display apparatus of this invention is applied. The figure for demonstrating the effect | action of the light emission operation | movement of the organic electroluminescent display apparatus to which 1st Embodiment of the display apparatus of this invention is applied. Schematic configuration diagram of an organic EL display device to which a second embodiment of the display device of the present invention is applied The figure which shows an example of the VGS-ID characteristic of the inorganic oxide film thin-film transistor whose threshold voltage which carries out an off operation is a negative voltage The figure for demonstrating the effect | action of an aging operation | movement at the time of using the inorganic oxide film thin-film transistor whose threshold voltage which carries out an off operation is a negative voltage as a drive transistor A diagram for explaining an aging operation in a conventional organic EL display device The figure which shows an example of the pixel circuit of the conventional organic electroluminescence display

  Hereinafter, an organic EL display device to which a first embodiment of a display device of the present invention is applied will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of an organic EL display device to which the first embodiment of the present invention is applied.

  As shown in FIG. 1, the organic EL display device according to the first embodiment of the present invention includes an active matrix substrate 10 in which a large number of pixel circuits 11 each having an organic EL light emitting element are two-dimensionally arranged, and each pixel circuit 11. A scan drive circuit 12 for outputting a gate scan signal and a source scan signal to each other, a gate drive circuit 13 for outputting a program voltage to a drive transistor of each pixel circuit 11 based on display data corresponding to image data, and an aging operation A reset voltage drive circuit 14 for supplying an aging operation voltage and a reset voltage to a reset voltage line, which will be described later, and a timing signal based on display data and a synchronization signal corresponding to the image data are output to the gate drive circuit 13 and scanned. A timing signal based on the synchronization signal is output to the drive circuit 12 and the reset voltage drive circuit 14. And a control unit 19 for.

  The active matrix substrate 10 supplies a number of data lines 15 for supplying a program voltage output from the gate drive circuit 13 to each pixel circuit column and a gate scan signal output from the scan drive circuit 12 to each pixel circuit row. A large number of gate scan lines 16 to be supplied, a large number of source scan lines 17 for supplying source scan signals output from the scan drive circuit 12 to each pixel circuit row, and an aging operation voltage output from the reset voltage drive circuit 14 Are provided to each pixel circuit column.

  The data line 15 and the reset voltage line 18, and the gate scanning line 16 and the source scanning line 17 are provided in a lattice shape so as to be orthogonal to each other. A pixel circuit 11 is provided in the vicinity of these intersections.

  As shown in FIG. 2, each pixel circuit 11 includes an organic EL light emitting element 11a, a source terminal S connected to the anode terminal of the organic EL light emitting element 11a, and a driving transistor 11b that passes a driving current through the organic EL light emitting element 11a. And the capacitive element 11c connected between the gate terminal G and the source terminal S of the driving transistor 11b, and one end of the capacitive element 11c and between the gate terminal G of the driving transistor 11b and the data line 15. The gate selection transistor 11d and the other end of the capacitor 11c and the source transistor 11e connected between the source terminal S of the driving transistor 11b and the reset voltage line 18 are provided.

  The organic EL light emitting element 11 a includes a light emitting unit 50 that emits light by a driving current passed by the driving transistor 11 b and a parasitic capacitance 51 of the light emitting unit 50. The cathode terminal of the organic EL light emitting element 11a is connected to a common potential (ground potential in FIG. 2).

  The driving transistor 11b, the gate selection transistor 11d, and the source transistor 11e are N-type thin film transistors. As a kind of the thin film transistor of the driving transistor 11b, an amorphous silicon thin film transistor or an inorganic oxide thin film transistor can be used. As the inorganic oxide film thin film transistor, for example, a thin film transistor made of an inorganic oxide film made of IGZO (InGaZnO) can be used. However, not only IGZO but also IZO (InZnO) can be used.

  The scanning drive circuit 12 sequentially outputs a gate scan signal ScanG for turning on / off the gate selection transistor 11d of the pixel circuit 11 to each gate scanning line 16 based on the timing signal output from the control unit 19. The source scan signal ScanS for turning on / off the source transistor 11e is sequentially output to each source scan line 17.

  The gate drive circuit 13 generates a program voltage input to each pixel circuit 11 based on the input display data, and outputs the program voltage to each data line 15.

  The reset voltage drive circuit 14 switches and outputs an aging operation voltage VE and a reset voltage VA, which will be described later. Specifically, each reset voltage line 18 is supplied to each reset voltage line 18 during an aging operation of the organic EL light emitting element 11a which will be described later. An aging operation voltage VE is supplied, and a reset voltage VA is supplied to each reset voltage line 18 during a reset operation described later.

  Next, the operation of the organic EL display device according to the first embodiment will be described in detail.

  In the organic EL display device of this embodiment, the aging operation of the organic EL light emitting element 11a of each pixel circuit 11 is performed before the display operation based on the display data. In the present embodiment, the case where the organic EL light emitting elements 11a of all the pixel circuits 11 are simultaneously aged will be described. However, the present invention is not limited to this, and the aging operations of some of the pixel circuits 11 are sequentially switched. Also good. Such a case will be described in detail in a second embodiment of the present invention described later.

  When performing an aging operation, first, a gate scan signal for turning on the gate selection transistors 11d is output from the scan drive circuit 12 to all the gate scan lines 16, and the source scan line 17 is supplied with a source signal. A source scan signal for turning on the transistor 11e is output.

  As shown in FIG. 3, the gate selection transistors 11d of all the pixel circuits 11 are turned on in accordance with the gate scan signal output from the scan driving circuit 12, and all the pixel circuits 11 are in response to the source scan signal. Source transistor 11e is turned on, the gate terminal G of the driving transistor 11b of all the pixel circuits 11 and the data line 15 are connected, and the source terminal S of the driving transistor 11b and the reset voltage line 18 are connected. Is done.

  On the other hand, the aging operation voltage VE is output from the reset voltage driving circuit 14 to all the reset voltage lines 18, and at this time, all the program voltages Vdata having the same magnitude as the aging operation voltage VE are also output from the gate driving circuit 13. Are output to the data line 15.

  The voltage for aging operation supplied to the reset voltage line 18 is supplied to the organic EL light emitting element 11a via the source transistor 11e, and a driving current flows through the organic EL light emitting element 11a to perform a light emitting operation for aging. Is called. At this time, as described above, the program voltage Vdata having the same magnitude as the aging operation voltage VE is also output from the gate drive circuit 13 to all the data lines 15, and is supplied to the gate terminals G of all the drive transistors 11b. Since the program voltage Vdata having the same magnitude as the aging operation voltage VE is supplied, the gate-source voltage Vgs of the driving transistor 11b is fixed to 0V. Therefore, since no driving current flows through the driving transistor 11b, the threshold voltage Vth of the driving transistor 11b can be prevented from shifting.

  Then, after the aging operation of the organic EL light emitting element 11a is performed as described above, the display operation based on the display data is performed.

  Next, the display operation based on the display data will be described with reference to the timing chart shown in FIG. 4 and FIGS. 4 shows the voltage waveform of the gate scan signal ScanG output from the scan drive circuit 12, the voltage waveform of the source scan signal ScanS output from the scan drive circuit 12, and the gate voltage Vg of the drive transistor 11b. The voltage waveforms of the source voltage Vs and the gate-source voltage Vgs are shown.

  In the organic EL display device of this embodiment, pixel circuit rows connected to the gate scanning lines 16 of the active matrix substrate 10 are sequentially selected, and a predetermined operation is performed in the selection period in units of one row. Here, an operation performed in the selected period in the selected predetermined pixel circuit row will be described.

  First, a reset operation is performed on the pixel circuit row (time t1 to time t2 in FIG. 4, see FIG. 5).

  Specifically, as shown in FIG. 4, a gate scan signal ScanG for turning on the gate selection transistor 11 d is output from the scan drive circuit 12 to the gate scan line 16, and the source scan line is supplied from the scan drive circuit 12. 17, a source scan signal ScanS for turning on the source transistor 11e is output. Then, as shown in FIG. 5, the gate selection transistor 11d is turned on in response to the gate scan signal ScanG, and the gate terminal G of the driving transistor 11b is connected to the data line 15. Further, the source transistor 11e is turned on in response to the source scan signal ScanS, the source terminal S of the driving transistor 11b and one end of the capacitive element 11c (on the side opposite to the gate terminal of the driving transistor 11b), and the reset voltage line 18 And are connected.

  At this time, a predetermined voltage VB is output from the gate drive circuit 13 to each data line 15 and supplied to the gate terminal G of the drive transistor 11b of each pixel circuit 11, and from the reset voltage drive circuit 14 to each reset voltage line. The reset voltage VA is output to 18 and supplied to the source terminal S of the driving transistor 11 b of each pixel circuit 11. In the present embodiment, the reset voltage is set to 0V.

  By the above operation, the gate voltage Vg = VB and the source voltage Vs = VA = 0 of the driving transistor 11b are set, and the gate-source voltage Vgs = VB-VA of the driving transistor 11b is set. The parasitic capacitance 51 is reset.

  Here, given that the predetermined voltage VB is Vb> VA + Vthmax, where the maximum value of the threshold voltage of the driving transistor 11b is Vthmax, a certain driving current Id flows from the driving transistor 11b to the reset voltage line 18. is there.

  The reset voltage VA is VA <Vf0−ΔVth, where the light emission threshold voltage of the organic EL light emitting element 11a is Vf0 and the threshold voltage deviation of the driving transistor 11b + the maximum value of fluctuation is ΔVth. Although VA = 0V is set as in the embodiment, when ΔVth is small, the light emission transition time of the organic EL light emitting element 11a can be shortened by setting a higher voltage, and conversely, when ΔVth is large, It is necessary to set a lower voltage (including a negative voltage).

  Next, a threshold voltage detection operation is performed (time t2 to time t3 in FIG. 4, see FIG. 6).

  Specifically, as shown in FIG. 4, a source scan signal ScanS for turning off the source transistor 11 e is output from the scan drive circuit 12 to the source scan line 17. Then, as shown in FIG. 6, the source transistor 11e is turned off in response to the source scan signal ScanS.

As a result, as shown in FIG. 6, the source terminal S of the driving transistor 11b and the reset voltage line 18 are cut off. At this time, the gate-source voltage Vgs of the driving transistor 11b is
Vgs = Vg−Vs = VB−VA> Vth
Therefore, the driving current Id flowing from the driving transistor 11b to the reset voltage line 18 flows to the parasitic capacitance 51 of the organic EL light emitting element 11a, and the parasitic capacitance 51 is charged, and the source terminal of the driving transistor 11b The source voltage Vs of S increases.

  Since VB supplied to the gate terminal G of the driving transistor 11b is a fixed voltage, Vgs decreases as the source voltage Vs increases, and when Vgs = Vth, the driving current Id = 0 and the source voltage Vs The ascent stops. Note that the voltage across the capacitor 11c at this time is Vcs = Vgs = Vth.

Here, at this time, the gate voltage Vg of the driving transistor 11b is Vg = VB, the source voltage Vs = VB−Vth, and the source voltage Vs needs to be equal to or lower than the light emission threshold voltage of the organic EL light emitting element 11a.
VB <Vf0 + Vthmin
Is a condition. Vf0 is a light emission threshold voltage of the organic EL light emitting element 11a, and Vthmin is a minimum threshold voltage of the driving transistor 11b.

  Next, a program operation is performed (time t3 to time t4 in FIG. 4, see FIG. 7). When the source voltage of the driving transistor 11b is sufficiently stabilized by the threshold voltage detection operation, the gate driving circuit 13 steps up the voltage output to each data line 15 from the predetermined voltage VB to the program voltage Vprg = VB + Vod.

Here, Vod is a driving voltage of the driving transistor 11b for causing a driving current corresponding to a desired luminance to flow through the organic EL light emitting element 11a, and Vod = Vgs−Vth. Since the source voltage Vs of the driving transistor 11b is divided by the capacitance value Cs of the capacitive element 11c and the capacitance value Cd of the parasitic capacitance 51,
Vs = VB−Vth + Vod × Cs / (Cd + Cs)
However, if Cd >> Cs,
Vs≈VB-Vth
Vgs≈VB + Vod− (VB−Vth) = Vth + Vod
Thus, Vd is added to Vth detected by the capacitive element 11c.

  Then, a light emission operation is performed next (see FIG. 8 after time t4 in FIG. 4).

  Specifically, as shown in FIG. 4, a gate scan signal ScanG for turning off the gate selection transistor 11d is output from the scan drive circuit 12 to the gate scan line 16, and as shown in FIG. Accordingly, the gate selection transistor 11d is turned off. As a result, the connection between the gate terminal G of the driving transistor 11b and the data line 15 is cut off.

  Then, as shown in FIG. 8, a driving current Id corresponding to the driving voltage flows through the driving transistor 11b while holding the voltage across the capacitive element 11c in the above-described programming operation. The light emitting unit 50 of the EL light emitting element 11a emits light. Note that after the application of Vod is completed, it is necessary to turn off the gate selection transistor 11d before the source voltage Vs of the driving transistor 11b increases.

  Next, an organic EL display device to which the second embodiment of the display device of the present invention is applied will be described.

  In the organic EL display device of the first embodiment, the aging operation of the organic EL light emitting element 11a is performed simultaneously for all the pixel circuits 11. However, the organic EL display device of the second embodiment is partially By sequentially switching the pixel circuits 11 and performing an aging operation, the aging operation of all the pixel circuits 11 is finally performed. In this way, heat generation during the aging operation can be suppressed by performing the aging operation only on a part of the pixel circuits 11.

  Specifically, the organic EL display device of the second embodiment is different from the organic EL display device of the first embodiment in that the configuration of the reset voltage drive circuit 20 and the drive control method of the control unit 19 that drives and controls the reset voltage drive circuit 20 are the same. The other configurations are the same as those of the organic EL display device of the first embodiment.

  The reset voltage drive circuit 20 of the organic EL display device according to the second embodiment outputs the voltage for aging operation by sequentially switching the reset voltage lines 18.

  The operation of the pixel circuit 11 connected to the reset voltage line 18 to which the aging operation voltage is supplied is the same as the aging operation described in the organic EL display device of the first embodiment. At this time, for example, the reset voltage VA may be output from the reset voltage drive circuit 20 to the reset voltage line 18 to which the aging operation voltage is not supplied. At this time, for the data line 15 connected to the pixel circuit 11 that has not been subjected to the aging operation, the gate-source voltage Vgs of the driving transistor 11b is set to 0 V, so that it has the same magnitude as the reset voltage VA. It is desirable to supply the program voltage Vprg to the data line 15. Note that the voltage supplied to the reset voltage line 18 and / or the data line 15 connected to the pixel circuit 11 that has not been subjected to the aging operation is set to a voltage lower than the light emission threshold voltage Vf0 of the organic EL light emitting element 11a. There is a need.

  In the above description, the aging operation is performed for each pixel circuit column connected to each reset voltage line 18; however, the aging operation is performed for each pixel circuit column group including a plurality of pixel circuit columns, not for each pixel circuit column. For example, all pixel circuit columns may be divided into two equal parts, and an aging operation may be performed for each pixel circuit column group including half pixel circuit columns. Further, the aging operation may be performed by switching the R, G, and B pixel circuit rows, and the aging operation voltage corresponding to the characteristics of the organic EL light emitting element of each pixel circuit may be supplied to the reset voltage line 18. Good.

  In the organic EL display devices of the first and second embodiments, the driving transistor 11b does not flow when the gate-source voltage Vgs is 0V, that is, the threshold voltage Vth is less than 0V. However, the present invention is not limited to this, and an inorganic oxide thin film transistor having a negative threshold voltage for the off operation may be used as the driving transistor 11b. Here, the threshold voltage for the off operation refers to a gate-source voltage at which the drain current ID starts to increase rapidly. The threshold voltage for the off operation is a negative voltage, for example, VGS as shown in FIG. -Having ID characteristics. Note that the threshold voltage in the VGS-ID characteristic of FIG. 10 is VTH. As the inorganic oxide film thin film transistor, for example, a thin film transistor made of an inorganic oxide film made of IGZO (InGaZnO) can be used. However, the thin film transistor is not limited to IGZO, and other materials include ZnO. The threshold voltage of the IGZO thin film transistor can be set by the composition ratio of In, Ga, and Zn.

  When an inorganic oxide thin film transistor having a negative threshold voltage for the off operation is used as the driving transistor 11b, a driving current flows even when the gate-source voltage Vgs = 0 of the driving transistor 11b. In addition, an error occurs in the aging operation of the organic EL light emitting element 11a, or a threshold voltage shift of the driving transistor 11b occurs. Therefore, in this case, as shown in FIG. 11, the power supply voltage Vdd connected to the drain terminal D of the driving transistor 11b is set to the same level as the aging operation voltage VE, so that the drain of the driving transistor 11b By setting the potentials of all the terminals D, the gate terminal G, and the source terminal S to be the same, an error in the aging operation can be prevented.

  Although the threshold voltage shift of the driving transistor 11b can be prevented in the driving control method of the aging operation of the present invention, there is a possibility that the threshold voltage shift occurs in the source transistor 11e. However, the source transistor 11e is provided to discharge the parasitic capacitance 51 and the capacitance element 11c of the organic EL light emitting element 11a during the reset operation. Unlike the driving transistor 11b that controls the current value, Even if the voltage is shifted, the influence of the threshold voltage shift can be eliminated by setting the amplitude of the source scan signal in consideration of the shift, and the display image quality is not affected.

  In the organic EL display devices of the first and second embodiments, the DC voltage is used as the aging operation voltage during the aging operation. However, the present invention is not limited to this, and a pulse voltage may be used. .

  In the embodiment of the present invention, the display device of the present invention is applied to an organic EL display device. However, the light emitting element is not limited to the organic EL light emitting element, and for example, an inorganic EL element is used. It may be.

  The display device of the present invention has various uses. For example, a portable information terminal (electronic notebook, mobile computer, mobile phone, etc.), a video camera, a digital camera, a personal computer, a television, etc. are mentioned.

DESCRIPTION OF SYMBOLS 10 Active matrix substrate 11 Pixel circuit 11a Organic EL light emitting element 11b Driving transistor 11c Capacitance element 11d Gate selection transistor 11e Source transistor 12 Scan driving circuit 13 Gate driving circuit 14, 20 Reset voltage driving circuit 15 Data line 16 Gate scanning line 17 Source scan line 18 Reset voltage line 19 Control unit 20 Reset voltage drive circuit 50 Light emitting unit 51 Parasitic capacitance

Claims (8)

A light emitting element, an N-type driving transistor having a source terminal connected to the anode terminal of the light emitting element and supplying a driving current to the light emitting element, and a capacitive element connected between the gate terminal and the source terminal of the driving transistor A selection transistor connected between a gate terminal of the driving transistor and a signal line for supplying a driving voltage to the gate terminal of the driving transistor, and a source terminal of the driving transistor and a source of the driving transistor In a drive control method of a display device including an active matrix substrate in which a plurality of pixel circuits each including a source transistor connected between a reset voltage line that supplies a reset voltage to a terminal are arranged,
A drive control method for a display device, wherein an aging operation of the light emitting element is performed by passing a current through the light emitting element through the reset voltage line and a source terminal of the driving transistor.   2. The display device drive control method according to claim 1, wherein a threshold voltage detection operation of the drive transistor is performed by charging a parasitic capacitance of the light emitting element with a drive current of the drive transistor.   The aging operation voltage having the same magnitude is supplied to the signal line and the reset voltage line by turning on the selection transistor and the source transistor during the aging operation of the light emitting element. 3. A drive control method for a display device according to 1 or 2. A light emitting element, an N-type driving transistor having a source terminal connected to the anode terminal of the light emitting element and supplying a driving current to the light emitting element, and a capacitive element connected between the gate terminal and the source terminal of the driving transistor A selection transistor connected between a gate terminal of the driving transistor and a signal line for supplying a driving voltage to the gate terminal of the driving transistor, and a source terminal of the driving transistor and a source of the driving transistor In a display device including an active matrix substrate in which a large number of pixel circuits each including a source transistor connected between a reset voltage line that supplies a reset voltage to a terminal are arranged,
A display device comprising: a control unit that controls to perform an aging operation of the light emitting element by causing a current to flow through the light emitting element through the reset voltage line and a source terminal of the driving transistor.   5. The control unit controls the threshold voltage detection operation of the driving transistor by charging a parasitic capacitance of the light emitting element with a driving current of the driving transistor. Display device.   The controller controls to turn on the selection transistor and the source transistor to supply the same voltage for aging operation to the signal line and the reset voltage line during the aging operation of the light emitting element. The display device according to claim 4, wherein the display device is a device. The driving transistor is a thin film transistor having a negative threshold voltage;
The control unit controls to supply the aging operation voltage to the power supply voltage line connected to the drain terminal of the driving transistor during the aging operation of the light emitting element. The display device according to any one of claims 4 to 6. The active matrix substrate includes a large number of the signal lines and a large number of the reset voltage lines;
The control unit sequentially switches a part of the reset voltage lines among the plurality of reset voltage lines and sequentially supplies the aging operation voltage to the part of the reset voltage lines, and the aging operation voltage is supplied. It is controlled to supply a voltage lower than a light emission threshold voltage of a light emitting element of the pixel circuit to the reset voltage line and / or the signal line connected to the pixel circuit which is not performed. The display device according to any one of claims 4 to 7.