Source: http://www.google.com/patents/US7714814?dq=7,468,661
Timestamp: 2015-04-26 20:24:47
Document Index: 224602343

Matched Legal Cases: ['art 42', 'art 62', 'art 142', 'art 142', 'art 162', 'art 162', 'art 242', 'art 262']

Patent US7714814 - Method and apparatus for driving electro-luminescence display panel with an ... - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsThe present invention relates to a method and apparatus for driving an electro-luminescence display panel capable of doing an aging operation upon driving. A method of driving an electro-luminescence display panel according to the present invention includes: a scan period when electro-luminescence cells...http://www.google.com/patents/US7714814?utm_source=gb-gplus-sharePatent US7714814 - Method and apparatus for driving electro-luminescence display panel with an aging pulseAdvanced Patent SearchPublication numberUS7714814 B2Publication typeGrantApplication numberUS 11/205,164Publication dateMay 11, 2010Filing dateAug 17, 2005Priority dateAug 18, 2004Fee statusPaidAlso published asEP1628284A2, EP1628284A3, US8159425, US20060038756, US20090174694Publication number11205164, 205164, US 7714814 B2, US 7714814B2, US-B2-7714814, US7714814 B2, US7714814B2InventorsHyo Dae Bae, Hak Su KimOriginal AssigneeLg Electronics Inc.Export CitationBiBTeX, EndNote, RefManPatent Citations (23), Classifications (11), Legal Events (2) External Links: USPTO, USPTO Assignment, EspacenetMethod and apparatus for driving electro-luminescence display panel with an aging pulse
US 7714814 B2Abstract
1. A method of driving an electro-luminescence display panel comprising:
applying a scan pulse and a data signal in a scan period to a plurality of electro-luminescence cells formed between a plurality of scan lines and a plurality of data lines; and
floating the plurality of data lines and applying an aging voltage to adjacent scan lines to perform a self-aging of an electro-luminescence cell disposed between two scan lines in an aging period,
wherein the aging voltage differs from a voltage of the scan pulse, and the aging voltage is inverted relative to the adjacent scan lines.
2. The method according to claim 1, wherein any one aging voltage of high and low aging voltages is applied to an odd-numbered scan line, and an aging voltage opposite to the aging voltage of the odd-numbered scan line is applied to an even-numbered scan line, in the aging period.
3. The method according to claim 2, wherein the aging voltage applied to the plurality of scan lines is reversed at least one time in the aging period.
4. The method according to claim 2, wherein the aging period is divided into a plurality of periods, and the aging voltage applied to each of the scan lines is reversed for each boundary spot of the divided periods.
5. The method according to claim 2, wherein a low scan voltage is supplied to a scan line for an enable and a first high scan voltage is supplied to a scan line for a disable, in the scan period, and
wherein a second high scan voltage larger than the first high scan voltage or equal to the first high scan voltage is supplied as the high aging voltage, and the low scan voltage is supplied as the low aging voltage, in the aging period.
6. The method according to claim 1, wherein the aging voltage applied to the plurality of scan lines is reversed at least one time in the aging period.
7. The method according to claim 1, wherein the aging period is divided into a plurality of periods, and the aging voltage applied to each of the scan lines is reversed for each boundary spot of the divided periods.
8. The method according to claim 1, wherein the scan period and the aging period are repeated for each frame.
9. The method according to claim 1, wherein the aging period is disposed in an end of the scan period.
10. The method according to claim 1, wherein the scan period comprising a dummy period of a non-emitting section of the electro-luminescence cells.
11. An apparatus of driving an electro-luminescence display panel, comprising:
a scan driver to apply a scan pulse to a scan line in the scan period and to apply an aging voltage in the aging period to adjacent scan lines having a voltage difference; and
an electro-luminescence display panel having an electro-luminescence cell formed for each a cross of both the scan line and the data line, wherein the electro-luminescence cell is emitted in accordance with the data signal in the scan period and a self-aging is performed in the electro-luminescence cell in the aging period,
12. The apparatus according to claim 11, wherein the scan driver applies any one aging voltage of high and low aging voltages to an odd-numbered scan line, and applies an aging voltage opposite to an aging voltage of the odd-numbered scan line to an even-numbered scan line, in the aging period.
13. The apparatus according to claim 11, wherein the scan driver repeats the scan period and the aging period for each frame.
14. The apparatus according to claim 11, wherein the scan driver includes:
a level shifter part having a plurality of level shifters to level-shift each of the output signals of the shift register to supply the scan pulse to the scan line in the scan period and to supply an aging voltage opposite to an aging voltage of the adjacent scan lines in the aging period.
15. The apparatus according to claim 14, wherein each of the stages supplies an enable signal corresponding to the shifted start pulse, and
wherein the level shifter part divides the aging period into a plurality of period when the enable signal is outputted in the each dummy stage, and reverses the aging voltage applied to each of the scan lines for each boundary spot of the divided periods.
16. The apparatus according to claim 11, wherein the scan driver includes:
17. The apparatus according to claim 16, wherein the start pulse of the next stage is delayed to be supplied to include the aging period after the scan period.
18. The apparatus according to claim 11, wherein the aging period is disposed in an end of the scan period. Description
This application claims the benefit of Korean Patent Application No. P2004-65087 filed in Korea on Aug. 18, 2004, No. P2004-70600 and No. P2004-70601, filed in Korea on Sep. 4, 2004, and No. P2004-118586 filed in Korea on Dec. 31, 2004, which are hereby incorporated by reference.
The EL display device includes: an anode formed of a transparent conductive material on a substrate; and a hole injection layer, a hole carrier layer, a light-emitting layer, an electron carrier layer, and an electron injection layer made of an organic material, and a cathode made of a metal having a low work function, which are disposed thereon. If a forward voltage is applied between the anode and the cathode, then electrons generated from the cathode move via the electron injection layer and the electron carrier layer to the light-emitting layer and holes generated from the anode moves via the hole injection layer and the hole carrier layer to the light-emitting layer. Accordingly, the electrons and the holes fed from the electron carrier and the hole carrier layer are recombined each other in the light-emitting layer, to thereby emit light. In this case, the brightness of the organic EL device is in portion to a current between the anode and the cathode.
The EL display device shown in FIG. 1 includes: an EL panel 20 having an EL cell 26 formed at a cross of both scan lines SL1 to SLn and data lines DL1 to DLm; a scan driver 22 for driving the scan lines SL1 to SLn; and a data driver 24 for driving the data lines DL1 to DLm.
Each of the EL cells 26 formed in the EL panel 20 is represented as a diode, which is connected in a forward direction between the data line DL and the scan line SL. Herein, the data line DL is equivalently an anode and the scan line SL is equivalently a cathode. If a negative scan pulse, that is, a low scan voltage Vlow, is supplied to the scan line SL and a positive data signal(current) is supplied to the data line DL to as shown in FIG. 2 apply a forward voltage to each EL cell 26, then each EL cell 26 emits light to generate light corresponding to the data signal. On the other hand, if a high scan voltage Vhigh is supplied to the scan line SL to thereby apply a reverse voltage to each EL cell 26, then each EL cell 26 does not emit light.
For this, the scan driver 32 includes: a shift register 40, which outputs a n number of output signals S1 to Sn as sequentially shifting a start pulse Vst inputted by a frame Fi unit, and makes to secure an aging period APD; and a level shifter part 42 to level-shift each of output signals Si to Sn of the shigt register 40 to supply it to each of scan lines SL1 to SLn.
Each of the EL cells 36 formed in the EL panel 30 is represented as a diode, which is connected in a forward direction between the data line DL and the scan line SL. Herein, the data line DL is equivalently an anode and the scan line SL is equivalently a cathode. If a low scan voltage Vlow, is supplied to the scan line SL and a positive data signal(current) is supplied to the data line DL to apply a forward voltage to each EL cell 36, then each EL cell 36 emits light to generate light corresponding to the data signal. On the other hand, if high scan voltages Vhigh1 and Vhigh2 are supplied to the scan line SL to thereby apply a reverse voltage to each EL cell 36, then each EL cell 36 does not emit light. Especially, if the second high scan voltage is supplied to the entire scan lines SL1 to SLn and the low voltage is supplied to the entire data lines DL1 to DLm in the aging period, then each of the EL cells 36 becomes a reverse bias state for the aging. Accordingly, it is possible to extend a life-span of the EL panel 30 and to prevent badness such as line defect.
The scan driver 52 includes: a shift register 60, which outputs a n number of output signals S1 to Sn as sequentially shifting a start pulse Vst inputted by a frame Fi unit; and a level shifter part 62 to level-shift each of output signals S1 to Sn of the shigt register 60 to supply it to each of scan lines SL1 to SLn.
For instance, as shown in FIG. 8, as the data lines DL1 to DLm are floated, a second high scan voltage Vhigh, i.e., a high aging voltage, is applied to the odd-numbered scan lines SL1, SL3, . . . , SLn-1, whereas, a low scan voltage Vlow, i.e., a low aging voltage, is applied to the even-numbered scan lines SL2, SL4, . . . , SLn. Or, the low scan voltage Vlow is applied to the odd-numbered scan lines SL1, SL3, . . . , SLn-1, and the second high scan voltage Vhigh2 is applied to the even-numbered scan lines SL2, SL4, . . . , SLn. Accordingly, a self-aging is performed in the EL cells by a voltage difference between adjacent scan lines. Herein, the second high scan voltage Vhigh2, i.e., the high aging voltage, is set to be larger than the first high scan voltage Vhigh1 applied during the scan period SPD or to be equal to the first high scan voltage Vhigh1. For instance, the second high scan voltage Vhigh2 is set as a larger voltage as much as about 10% to 20% than the first scan high voltage Vhigh1.
For instance, as shown in FIG. 8, the aging period APD is divided into first and second periods A1 and A2. When the second high scan voltage Vhigh2 is applied to the odd-numbered scan lines SL1, SL3, . . . , SLn-1 and the low scan voltage Vlow is applied to the even-numbered scan lines SL2, SL4, . . . , SLn, during the first period A1, the voltage is reversed during the second period A2 to apply the low scan voltage to the odd-numbered scan lines SL1, SL3, . . . , SLn-1 and to apply the second high scan voltage Vhigh2 to the even-numbered scan lines SL2, SL4, . . . , SLn.
Each of the EL cells 136 formed in the EL panel 130 is represented as a diode, which is connected in a forward direction between the data line DL and the scan line SL. Herein, the data line DL is equivalently an anode and the scan line SL is equivalently a cathode. If a low scan voltage Vlow is supplied to the scan line SL and a positive data signal(current) is supplied to the data line DL to apply a forward voltage to each EL cell 136 in a scan period SPD, then each EL cell 136 emits light to generate light corresponding to the data signal. On the other hand, if a first high scan voltage Vhigh1 is supplied to the scan line SL to thereby apply a reverse voltage to each EL cell 136, then each EL cell 136 does not emit light. Further, If the data lines DL1 to DLn are floated, and voltages opposite to each other are applied to the odd-numbered scan lines SL1, SL3, . . . , SLn-1 and the even-numbered scan lines SL2, SL4, . . . , SLn, in the aging period APD, then the each of the EL cells 136 does not emit light and a self-aging is performed in the each of the EL cells 136.
The scan driver 132, as shown in FIG. 10, sequentially supplies a low scan voltage Vlow to the n number of scan lines SL1 to SLn in a scan period SPD of one frame Fi, and supplies a high scan voltage Vhigh in the rest period. Further, the scan driver 132 supplies aging voltages opposite to each other to the odd-numbered scan lines SL1, SL3, . . . , SLn-1 and the even-numbered scan lines SL2, SL4, . . . , SLn in the aging period APD of one frame Fi.
For this, the scan driver 132 includes: a shift register 140, which outputs a n number of output signals S1 to Sn as sequentially shifting a start pulse Vst inputted by a frame Fi unit, and makes to secure an aging period APD; and a level shifter part 142 to level-shift each of output signals Si to Sn of the shift register 140 to supply it to each of scan lines SL1 to SLn.
The shift register 140 includes: a n number of stages ST1 to STn for outputting the n number of output signals Si to Sn as shifting the start pulse; and a k number of dummy stages DST1 to DSTk to make to secure an aging period APD as shifting the output signal Sn of the nth stage STn.
The level shifter part 142 includes a n number of level shifters LS1 to LSn, which are respectively connected between the n number of stages ST1 to STn and the n number of scan lines SL1 to SLn. If the level shifters LS1 to LSn, as shown in FIG. 10, are supplied with the low voltage, i.e., an enable voltage of the output signals S1 to Sn from the shift register 140, in the scan period SPD, then the level shifters LS1 to LSn select a low scan voltage Vlow, whereas, if the level shifters LS1 to LSn are supplied with the high voltage of the output signals S1 to Sn from the shift register 140 in the scan period SPD, then the level shifters LS1 to LSn select a first high scan voltage Vhigh1. Accordingly, the level shifters LS1 to LSn supply the selected voltages to each of the scan lines SL1 to SLn. Further, if the level shifters LS1 to LSn, as shown in FIG. 10, are supplied with the high voltage of the output signals S1 to Sn from the shift register 140 in the aging period APD, then the entire level shifters LS1 to LSn supply voltages opposite to each other to the odd-numbered scan lines SL1, SL3, . . . , SLn-1 and the even-numbered scan line SL2, SL4, . . . , SLn by using the second high scan voltage Vhigh2 and the low scan voltage Vlow. Or, in order to raise an aging efficiency, a voltage is set to be reversed at least one time in the odd-numbered scan lines SL1, SL3, . . . , SLn-1 and the even-numbered scan lines SL2, SL4 . . . , SLn within the aging period APD.
For instance, when the second high scan voltage Vhigh2 is applied to the odd-numbered scan lines SL1, SL3, . . . , SLn-1 and the low scan voltage Vlow is applied to the even-numbered scan lines SL2, SL4, . . . , SLn, during the first period A1 of the aging period APD, the voltage is reversed during the second period A2 to apply the low scan voltage to the odd-numbered scan lines SL1, SL3, . . . , SLn-1 and to apply the second high scan voltage Vhigh2 to the even-numbered scan lines SL2, SL4, . . . , SLn.
Differently from this, as shown in FIG. 11, the aging period APD is divided into first to kth periods A1 to Ak, when the dummy stages DST1 to DSTk of the shift register 140 sequentially output a low voltage, i.e., an enable voltage. The opposite voltages Vhigh2 and Vlow applied to the odd-numbered scan lines SL1, SL3, . . . , SLn-1; SLodd and the even-numbered scan lines SL2, SL4, . . . , SLn; SLeven are set to be reversed for each boundary spot of the first to the kth periods A1 to Ak.
Or, as shown in FIG. 12, the opposite voltages Vhigh2 and Vlow applied to the odd-numbered scan lines SL1, SL3, . . . , SLn-1; SLodd and the even-numbered scan lines SL2, SL4, . . . , SLn; SLeven are set to be reversed one more time in the first to the kth periods A1 to Ak. In other words, the reverse period of the aging voltage applied to the odd-numbered scan line SLodd and the even-numbered scan line SLeven is set to be equal to each division period Ai of the aging period APD.
The scan driver 152 includes: a shift register 160, which outputs a n number of output signals Si to Sn as sequentially shifting a start pulse Vst inputted by a frame Fi unit; and a level shifter part 162 to level-shift each of output signals S1 to Sn of the shift register 160 to supply it to each of scan lines SL1 to SLn.
If a n number of level shifters LS1 to LSn included in the level shifter part 162, as shown in FIG. 14, are supplied with the low voltage of the output signals S1 to Sn from the shift register 160 in the scan period SPD, then the level shifters LS1 to LSn select a low scan voltage Vlow, whereas, if the level shifters LS1 to LSn are supplied with the high voltage of the output signals S1 to Sn from the shift register 160 in the scan period SPD, then the level shifters LS1 to LSn select a first high scan voltage Vhigh1. Accordingly, the level shifters LS1 to LSn supply the selected voltages to each of the scan lines SL1 to SLn. Further, if the level shifters LS1 to LS, as shown in FIG. 14, are supplied with the high voltage of the output signals S1 to Sn from the shift register 160 in the aging period APD, then the entire level shifters LS1 to LSn supply voltages opposite to each other to the odd-numbered scan lines SL1, SL3, . . . , SLn-1 and the even-numbered scan line SL2, SL4, . . . , SLn by using the second high scan voltage Vhigh2 and the low scan voltage Vlow. Or, in order to raise an aging efficiency, the voltage is set to be reversed at least one time in the odd-numbered scan lines SL1, SL3, . . . , SLn-1 and the even-numbered scan lines SL2, SL4 . . . , SLn within the aging period APD.
For instance, when the second high scan voltage Vhigh2 is applied to the odd-numbered scan lines SL1, SL3, . . . , SLn-1 and the low scan voltage Vlow is applied to the even-numbered scan lines SL2, SL4, . . . , SLn, during the first period A1 of the aging period APD, as shown in FIG. 14, the voltage is reversed during the second period A2 to apply the low scan voltage Vlow to the odd-numbered scan lines SL1, SL3, . . . , SLn-1 and to apply the second high scan voltage Vhigh2 to the even-numbered scan lines SL2, SL4, . . . , SLn.
In the aging period APD next the scan period SPD, as the entire data lines DL1 to DLm are floated, each of the scan lines SL1 to SLn has a voltage difference with an adjacent scan line. Accordingly, an optional voltage is applied to the EL cells in accordance with a state of the EL cells to make a self-aging of the EL cells. Especially, an aging voltage, which changes into a multilevel to have a voltage difference between the odd-numbered scan lines SL1, SL3, . . . , SLn-1 and the even-numbered scan lines SL2, SL4, . . . , SLn, is supplied to raise a self-aging efficiency. As a result, the EL cells become stabilized more and more.
For instance, as shown in FIG. 15, from a first step to a fifth step A1 to A5 in the aging period APD, an aging voltage, which is changed in a sequence of a low scan voltage Vlow, a middle voltage Vmiddle, a second high scan voltage Vhigh2, a middle voltage Vmiddle, and a low scan voltage Vlow, is supplied to the odd-numbed scan lines SL1, SL3, . . . , SLn-1. At this moment, an aging voltage, which is changed in a sequence of the second high scan voltage Vhigh2, the middle voltage Vmiddle, the low scan voltage Vlow, the middle voltage Vmiddle, and the second high scan voltage Vhigh2, is supplied to the even-numbered scan lines SL2, SL4, . . . , SLn oppositely to the odd-numbered scan lines SL1, SL3, . . . , SLn-1. Herein, the second high scan voltage Vhigh2, i.e., the high aging voltage, is set to be larger than the first high scan voltage Vhigh1 applied in the scan period SPD, or to be equal to the first high scan voltage Vhigh1. For instance, the second high scan voltage Vhigh2 is set as a larger voltage as much as about 10% to 20% than the first scan high voltage Vhigh1. The data lines DL1 to DLm are floated in the aging period APD.
Accordingly, a voltage difference between adjacent scan lines, i.e. the odd-numbed scan lines SL1, SL3, . . . , SLn-1 and the even-numbed scan lines SL2, SL4, . . . , SLn, makes that a self-aging is performed in the EL cells having the floated data lines DL1 to DLm. Further, the aging period APD includes a neutralization step when voltages of the odd-numbed scan lines SL1, SL3, . . . , SLn-1 and the even-numbed scan lines SL2, SL4, . . . , SLn become the same as the middle voltage Vmiddle. By the neutralization step, a parasitic capacitor formed in the EL panel can be reduced.
Referring to FIG. 16, in the aging period APD, an aging voltage AV1 to AVi, which changes into first to (2 i)th steps, is supplied to the odd-numbered scan lines SL1, SL3, . . . , SLn-1; SLodd, and an aging voltage AVi to AV1, which changed into the first to the (2 i)th steps A1 to A2 i, is supplied to the even-numbered scan lines SL2, SL4, . . . , SLn; SLeven in a direction opposite to the odd-numbered scan line SLodd.
More specifically, an aging voltage, which is decreased in a sequence of AV1, AV2, . . . , AVi-1, and AVi from the first to the (2 i)th steps A1 to A2 i of the aging period APD and then is again increased in a sequence of AVi-1, . . . , AV2, and AV1, is supplied to the odd-numbered scan line SLodd. On the other hand, an aging voltage, which is increased in a sequence of AVi, AVi-1, . . . , AV2, and AV1 and then is decreased in a sequence of AV2, . . . , AVi-1, and AVi, is supplied to the even-numbered scan line SLeven. Accordingly, a voltage difference between the odd-numbed and the even-numbed scan lines SLodd and SLeven is differentiated for each of the first to the (2 i)th steps A1 to A2 i. In other words, as shown in FIG. 16, the voltage difference between the odd-numbered and the even-numbered scan lines SLodd and SLeven is sequentially decreased in the first to the ith steps A1 to Ai, and is sequentially increased in the (i+1)th to the (2 i)th steps Ai+1 to A2 i, so that a self-aging is effectively performed in the EL cells. Further, oppositely to FIG. 16, when a multilevel aging voltage A1 to Ai is supplied to the odd-numbered and the even-numbered scan lines SLodd and SLeven, the voltage difference between the odd-numbered and the even-numbered scan lines SLodd and SLeven is sequentially increased and than is decreased in opposition to the above case. Thus, a self-aging is effectively performed in the EL cells.
More specifically, the even-numbered scan line SLeven is fixed with the low scan voltage Vlow, and the odd-numbered scan line SLodd is supplied with an aging voltage, which changes in a sequence of AV1, AV2, . . . , AVi-1, AVi, AVi-1, . . . AV2, and AV1 as shown in FIG. 17A, from the first to the (2 i)th steps A1 to A2 i. Or, the odd-numbered scan line SLodd is supplied with an aging voltage, which changes in a sequence of AVi, AVi-1, . . . , AV2, AV1, AV2, . . . , AVi-1, and AVi, as shown in FIG. 17B, from the first to the (2 i)th steps A1 to A2 i. On the other hand, the odd-numbered scan line SLodd is fixed with the low scan voltage Vlow, and the even-numbered scan line SLeven is supplied with an aging voltage, which changes in a sequence of AV1, AV2, . . . , AVi-1, AVi, AVi-1, . . . AV2, and AV1 as shown in FIG. 18A, from the first to the (2 i)th steps A1 to A2 i. Or, the even-numbered scan line SLeven is supplied with an aging voltage, which changes in a sequence of AVi, AVi-1, . . . , AV2, AV1, AV2, . . . , AVi-1, and AVi, as shown in FIG. 18B, from the first to the (2 i)th steps A1 to A2 i. Accordingly, a voltage difference between the odd-numbed and the even-numbed scan lines SLodd and SLeven is differentiated for each of the first to the (2 i)th steps A1 to A2 i. In other words, as shown in FIGS. 17A and 18B, a voltage difference between the odd-numbered and the even-numbered scan lines SLodd and SLeven is sequentially decreased and then increased in the first to the (2 i)th steps A1 to A2 i, so that a self-aging is effectively performed in the EL cells. On the other hand, as shown in FIGS. 17B and 18A, the voltage difference between the odd-numbered and the even-numbered scan lines SLodd and SLeven is sequentially increased and than is decreased in opposition to the above case. Thus, a self-aging is effectively performed in the EL cells.
In addition, in the aging period APD of the present invention, it is possible to repeat the above-described first to (2 i)th steps.
Each of the EL cells 236 formed in the EL panel 230 is represented as a diode, which is connected in a forward direction between the data line DL and the scan line SL. Herein, the data line DL is equivalently an anode and the scan line SL is equivalently a cathode. If a low scan voltage Vlow is supplied to the scan line SL and a positive data signal(current) is supplied to the data line DL to apply a forward voltage to each EL cell 236 in a scan period SPD, then each EL cell 236 emits light to generate light corresponding to the data signal. On the other hand, if a first high scan voltage Vhigh1 is supplied to the scan line SL to thereby apply a reverse voltage to each EL cell 236, then each EL cell 236 does not emit light. Further, If the data lines DL1 to DLn are floated, and a difference of voltage, changed to a multilevel is generated in the odd-numbered scan lines SL1, SL3, . . . , SLn-1 and the even-numbered scan lines SL2, SL4, . . . , SLn, in the aging period APD, then the each of the EL cells 236 does not emit light and a self-aging is performed in the EL cells 236.
The scan driver 232, as shown in FIG. 20, sequentially supplies a low scan voltage Vlow to the n number of scan lines SL1 to SLn in a scan period SPD of a frame Fi, and supplies a first high scan voltage Vhigh1 in the rest period. Further, the scan driver 232 supplies aging voltages, which is changed to a multilevel to make the odd-numbered scan lines SL1, SL3, . . . , SLn-1 and the even-numbered scan lines SL2, SL4, . . . , SLn have a voltage difference of a multilevel in the aging period APD of one frame Fi.
The level shifter part 242 includes a n number of level shifters LS1 to LSn, which are respectively connected between the n number of stages ST1 to STn and the n number of scan lines SL1 to SLn. If the level shifters LS1 to LSn, as shown in FIG. 20, are supplied with the low voltage, i.e., an enable voltage of the output signals S1 to Sn from the shift register 240, in the scan period SPD, then the level shifters LS1 to LSn select a low scan voltage Vlow, whereas, if the level shifters LS1 to LSn are supplied with the high voltage, i.e., a disable voltage, of the output signals S1 to Sn from the shift register 240 in the scan period SPD, then the level shifters LS1 to LSn select a first high scan voltage Vhigh1. Accordingly, the level shifters LS1 to LSn supply the selected voltages to each of the scan lines SL1 to SLn. Further, if the level shifters LS1 to LSn, as shown in FIG. 20, are supplied with the high voltage of the output signals S1 to Sn from the shift register 240 in the aging period APD, then the entire level shifters LS1 to LSn stepwise supply an aging voltage, which is changed in an opposite direction to the odd-numbered scan lines SL1, SL3, . . . , SLn-1 and the even-numbered scan lines SL2, SL4, . . . , SLn.
For instance, as shown in FIGS. 15 and 20, an aging voltage is changed in a sequence of Vhigh2, Vmiddle, Vlow, Vmiddle, and Vhigh2 in the odd-numbered scan lines SL1, SL3, . . . , SLn-1 from first to fifth steps A1 to A5, and an aging voltage is changed in a sequence of Vlow, Vmiddle, Vhigh2, Vmiddle, and Vlow in the even-numbered scan lines SL2, SL4, . . . , SLn from first to fifth steps A1 to A5. Or, as shown in FIGS. 16 to 18B, an aging voltage, which is changed from the first to the (2 i)th steps, is supplied.
If a n number of level shifters LS1 to LSn included in the level shifter part 262, as shown in FIG. 22, are supplied with the low voltage of the output signals S1 to Sn from the shift register 260 in the scan period SPD, then the level shifters LS1 to LSn select a low scan voltage Vlow, whereas, if the level shifters LS1 to LSn are supplied with the high voltage of the output signals S1 to Sn from the shift register 260 in the scan period SPD, then the level shifters LS1 to LSn select a first high scan voltage Vhigh1. Accordingly, the level shifters LS1 to LSn supply the selected voltages to each of the scan lines SL1 to SLn. Further, if the level shifters LS1 to LSn, as shown in FIG. 22, are supplied with the high voltage of the output signals S1 to Sn from the shift register 260 in the aging period APD, then the entire level shifters LS1 to LSn stepwise supply an aging voltage, which is changed in an opposite direction to the odd-numbered scan lines SL1, SL3, . . . , SLn-1 and the even-numbered scan lines SL2, SL4, . . . , SLn.
For instance, as shown in FIGS. 16 and 22, an aging voltage is changed in a sequence of Vhigh2, Vmiddle, Vlow, Vmiddle, and Vhigh2 in the odd-numbered scan lines SL1, SL3, . . . , SLn-1 from first to fifth steps A1 to A5, and an aging voltage is changed in a sequence of Vlow, Vmiddle, Vhigh2, Vmiddle, and Vlow in the even-numbered scan lines SL2, SL4, . . . , SLn from first to fifth steps A1 to A5. Or, as shown in FIGS. 16 to 18B, an aging voltage AV1 to AVi, which is changed from the first to the (2 i)th steps, is supplied.
Each of the EL cells 336 formed in the EL panel 330 is represented as a diode, which is connected in a forward direction between the data line DL and the scan line SL. Herein, the data line DL is equivalently an anode and the scan line SL is equivalently a cathode. If a low scan voltage Vlow, is supplied to the scan line SL and a positive data signal(current) is supplied to the data line DL in the scan period SPD to apply a forward voltage to each EL cell 336, then each EL cell 336 emits light to generate light corresponding to the data signal. On the other hand, if a high scan voltage is supplied to the scan line SL to thereby apply a reverse voltage to each EL cell 336, then each EL cell 336 does not emit light. Further, as the scan lines SL1 to SLm are floated, a voltage is applied to each of the data lines DL1 to DLn so that each of the data lines DL1 to DLn has a voltage difference with an adjacent data line. Accordingly, the each of the EL cells 336 does not emit light and a self-aging is performed in the EL cells 336.
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