DISPLAY DEVICE AND DRIVE METHOD THEREFOR

• US 20130181969A1
• Filed: 10/17/2011
• Published: 07/18/2013
• Est. Priority Date: 10/21/2010
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Kishi, Noritaka
• Granted Patent: US 8,933,865 B2
• Time in Patent Office: Days
• US Class Current: 345/212
• CPC Class Codes: G09G 2310/0283 Arrangement of drivers for different directions of scanning
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: G09G 3/3275 Details of drivers for data electrodes

Abstract

Provided is a display device that can sufficiently secure a period for threshold value detection with a simple configuration and that can inhibit occurrence of luminance non-uniformity. The display device includes a plurality of pixel circuits; a gate driver circuit connected to a plurality of scanning signal lines and a plurality of control lines; and a power control circuit connected to a plurality of power lines through a common power line. Each pixel circuit includes an organic EL element, a plurality of TFTs, and a capacitor. During each frame period, after initialization and threshold value detection are collectively performed on a plurality of rows, writing and light emission are performed sequentially on a row-by-row basis. Here, in a preceding frame (first frame) of two consecutive frame periods, writing is performed in order from the first row to the nth row (ascending order). In a subsequent frame (second frame) of the two frame periods, writing is performed in order from the nth row to the first row (descending order).

Claims

1. An active matrix-type display device comprising:

a plurality of pixel circuits arranged to form a matrix having a plurality of rows and a plurality of columns;

a plurality of video signal lines provided for the respective columns of the plurality of pixel circuits;

a plurality of scanning signal lines and a plurality of control lines provided for the respective rows of the plurality of pixel circuits;

a plurality of power lines provided to supply a power supply potential to the plurality of pixel circuits;

a column drive circuit that drives the plurality of video signal lines; and

a row drive circuit that drives the plurality of scanning signal lines and the plurality of control lines selectively or collectively, wherein

each of the pixel circuits includes;

an electro-optic element that emits light based on a current provided from the power line;

a driving transistor provided on a path of the current flowing through the electro-optic element;

a write control transistor that is provided between a control terminal of the driving transistor and the video signal line, and that electrically connects the control terminal of the driving transistor to the video signal line when the scanning signal line is activated by the row drive circuit;

a light emission control transistor that is provided between one conduction terminal of the driving transistor and the power line, and that electrically connects the one conduction terminal of the driving transistor to the power line when the control line is activated by the row drive circuit; and

a capacitor provided between the control terminal of the driving transistor and the other conduction terminal of the driving transistor, and

when focusing on each row group obtained when the plurality of rows are grouped into one or a plurality of row groups, the row drive circuit collectively activates all of scanning signal lines and control lines provided for respective rows belonging to the row group during an initialization period and a threshold value detection period, and selectively and sequentially activates the scanning signal lines provided for the respective rows belonging to the row group while selection order is reversed every k-frame period (k is a natural number), such that a write period for accumulating in the capacitors charge according to an image to be displayed is provided on a row-by-row basis, after the threshold value detection period, the initialization period being a predetermined period of time after start of a frame period and being a period for initializing the electro-optic element, and the threshold value detection period being a predetermined period of time after the initialization period and being a period for compensating for variations in the threshold voltage of the driving transistor.

2. The display device according to claim 1, wherein the k is 1.

3. The display device according to claim 1, further comprising:

a power control circuit that drives the plurality of power lines; and

for each of the row groups, a common power line connected in a shared manner to a group of the plurality of power lines, wherein

when focusing on each row group, the power control circuit provides an initialization potential, through a common power line corresponding to the row group, to power lines connected to the common power line during the initialization period, the initialization potential initializing the electro-optic element.

4. The display device according to claim 3, wherein the plurality of rows are grouped into a plurality of row groups.

5. The display device according to claim 4, wherein the plurality of rows are grouped such that a plurality of power lines belonging to a same row group are not adjacent to each other.

6. The display device according to claim 4, wherein the plurality of rows are grouped into three or more row groups.

7. The display device according to claim 1, further comprising, for each of the row groups, a common control line connected in a shared manner to a group of the plurality of control lines, wherein

when focusing on each row group, the row drive circuit activates a common control line corresponding to the row group, such that electro-optic elements in pixel circuits of all rows belonging to the row group emit light at same timing after completion of a write period for all rows belonging to the row group.

8. The display device according to claim 7, wherein the plurality of rows are grouped into one row group.

9. The display device according to claim 7, wherein the plurality of rows are grouped into a plurality of row groups.

10. The display device according to claim 7, further comprising:

a power control circuit that drives the plurality of power lines; and

for each of the row groups, a common power line connected in a shared manner to a group of the plurality of power lines, wherein

when focusing on each row group, the power control circuit provides an initialization potential, through a common power line corresponding to the row group, to power lines connected to the common power line during the initialization period, the initialization potential initializing the electro-optic element.

11. The display device according to claim 10, wherein the plurality of rows are grouped into a plurality of row groups.

12. The display device according to claim 11, wherein the plurality of rows are grouped such that a plurality of power lines belonging to a same row group are not adjacent to each other.

13. The display device according to claim 11, wherein the plurality of rows are grouped into three or more row groups.

14. The display device according to claim 1, wherein when focusing on each row group, during a period after the threshold value detection period and before a first write period for rows belonging to the row group starts, the row drive circuit collectively activates all scanning signal lines provided for the respective rows belonging to the row group, and the column drive circuit applies a reverse bias potential to the plurality of video signal lines, the reverse bias potential placing the driving transistor in a reverse bias state.

15. A drive method for an active matrix-type display device including a plurality of pixel circuits arranged to form a matrix having a plurality of rows and a plurality of columns;

a plurality of video signal lines provided for the respective columns of the plurality of pixel circuits;

a plurality of scanning signal lines and a plurality of control lines provided for the respective rows of the plurality of pixel circuits; and

a plurality of power lines provided to supply a power supply potential to the plurality of pixel circuits, the method comprising;

a column driving step of driving the plurality of video signal lines; and

a row driving step of driving the plurality of scanning signal lines and the plurality of control lines selectively or collectively, wherein

each of the pixel circuits includes;

an electro-optic element that emits light based on a current provided from the power line;

a driving transistor provided on a path of the current flowing through the electro-optic element;

a write control transistor that is provided between a control terminal of the driving transistor and the video signal line, and that electrically connects the control terminal of the driving transistor to the video signal line when the scanning signal line is activated in the row driving step;

a light emission control transistor that is provided between one conduction terminal of the driving transistor and the power line, and that electrically connects the one conduction terminal of the driving transistor to the power line when the control line is activated in the row driving step; and

a capacitor provided between the control terminal of the driving transistor and the other conduction terminal of the driving transistor, and

when focusing on each row group obtained when the plurality of rows are grouped into one or a plurality of row groups, in the row driving step, all of scanning signal lines and control lines provided for respective rows belonging to the row group are collectively activated during an initialization period and a threshold value detection period, and the scanning signal lines provided for the respective rows belonging to the row group are selectively and sequentially activated while selection order is reversed every k-frame period (k is a natural number), such that a write period for accumulating in the capacitors charge according to an image to be displayed is provided on a row-by-row basis, after the threshold value detection period, the initialization period being a predetermined period of time after start of a frame period and being a period for initializing the electro-optic element, and the threshold value detection period being a predetermined period of time after the initialization period and being a period for compensating for variations in the threshold voltage of the driving transistor.

16. The drive method according to claim 15, wherein the k is 1.

17. The drive method according to claim 15, wherein when focusing on each row group, during a period after the threshold value detection period and before a first write period for rows belonging to the row group starts, in the row driving step, all scanning signal lines provided for the respective rows belonging to the row group are collectively activated, and in the column driving step, a reverse bias potential is applied to the plurality of video signal lines, the reverse bias potential placing the driving transistor in a reverse bias state.