DISPLAY DEVICE

• US 20110216048A1
• Filed: 03/01/2011
• Published: 09/08/2011
• Est. Priority Date: 03/08/2010
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: YAMAZAKI, Shunpei, KOYAMA, Jun
• Granted Patent: US 9,013,389 B2
• Time in Patent Office: Days
• US Class Current: 345/204
• CPC Class Codes: G09G 2310/0286 Details of a shift registers arranged for use in a driving circuit
• CPC Class Codes: G09G 2310/0294 Details of sampling or holding circuits arranged for use in a driver for data electrodes
• CPC Class Codes: G09G 2310/04 Partial updating of the display screen
• CPC Class Codes: G09G 2320/103 Detection of image changes, e.g. determination of an index representative of the image change
• CPC Class Codes: G09G 3/3618 with automatic refresh of the display panel using sense/write circuits
• CPC Class Codes: G09G 3/3677 suitable for active matrices only

Abstract

A controller outputs a row rewriting control signal and a column rewriting control signal as well as a data signal. The row rewriting control signal is a signal selecting whether a selection signal is supplied to a first scan line, and the column rewriting control signal is a signal selecting whether a selection signal and a data signal are supplied to the second scan line and the signal line, respectively. The row rewriting control signal and the column rewriting control signal are thus output from the controller, which makes it possible to select whether a data signal is rewritten in each of a plurality of pixels arranged in matrix. Consequently, even in the case of displaying an image having a specific area, the display of which is often changed, a high-quality image can be displayed with reduced power consumption.

Claims

1. A display device comprising:

a controller configured to output a row rewriting control signal indicating whether there is a difference between successive two frames in at least one of a first pixel to an n-th pixel (n is a natural number of two or more) arranged in the same row, and a column rewriting control signal indicating whether there is a difference between the successive two frames in a k-th pixel (k is a natural number more than or equal to one and less than or equal to n);

a first scan line electrically connected to the first pixel to the n-th pixel, the first scan line being operationally connected to the controller;

a second scan line electrically connected to pixels arranged in the same column as the k-th pixel, the second scan line being operationally connected to the controller; and

a signal line electrically connected to the pixels arranged in the same column as the k-th pixel, the signal line being operationally connected to the controller,

wherein the k-th pixel comprises;

a first transistor, a gate of which is electrically connected to the first scan line and one of a source and a drain of which is electrically connected to the signal line; and

a second transistor, a gate of which is electrically connected to the second scan line and one of a source and a drain of which is electrically connected to the other of the source and the drain of the first transistor.

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

a shift register for driving the first scan line, which is configured to sequentially output selection signals from output terminals in a first sampling period for driving the first scan line;

a first latch for driving the first scan line, which is configured to retain the row rewriting control signal supplied when a selection signal is input, and output the row rewriting control signal in a vertical retrace period following the first sampling period for driving the first scan line;

a second latch for driving the first scan line, which is configured to retain the row rewriting control signal input from the first latch for driving the first scan line, and output the row rewriting control signal in the vertical retrace period and a second sampling period for driving the first scan line following the vertical retrace period; and

a buffer configured to select, in accordance with the row rewriting control signal input from the second latch for driving the first scan line, whether a selection signal is supplied to the first scan line in a horizontal scan period included in the second sampling period for driving the first scan line.

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

a shift register for driving the first scan line, which is configured to sequentially output selection signals from output terminals; and

an AND gate whose first input terminal is electrically connected to any of the output terminals of the shift register for driving the first scan line, whose second input terminal is electrically connected to a wiring supplying the row rewriting control signal, and whose output terminal is electrically connected to the first scan line.

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

a shift register for driving the signal line and the second scan line, which is configured to sequentially output selection signals from output terminals in a first sampling period for driving the signal line and the second scan line;

a first latch for driving the signal line and the second scan line, which is configured to retain the column rewriting control signal supplied when a selection signal is input, and output the column rewriting control signal in a horizontal retrace period following the first sampling period for driving the signal line and the second scan line;

a second latch for driving the signal line and the second scan line, which is configured to retain the column rewriting control signal output from the first latch for driving the signal line and the second scan line, and output the column rewriting control signal to the second scan line in a horizontal scan period including the horizontal retrace period and a second sampling period for driving the signal line and the second scan line following the horizontal retrace period;

a third latch for driving the signal line and the second scan line, which is configured to retain a data signal supplied when a selection signal is input, and output the data signal in the horizontal retrace period;

a fourth latch for driving the signal line and the second scan line, which is configured to retain the data signal output from the third latch for driving the signal line and the second scan line, and outputs the data signal in the horizontal scan period;

a digital to analog converter circuit which is configured to convert the data signal output from the fourth latch for driving the signal line and the second scan line into an analog data signal; and

an analog buffer which is configured to select, in accordance with the column rewriting control signal, whether the analog data signal is supplied to the signal line in the horizontal scan period.

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

a shift register for driving the signal line and the second scan line, which is configured to sequentially output selection signals from output terminals;

an AND gate whose first input terminal is electrically connected to any of the output terminals of the shift register for driving the signal line and the second scan line, whose second input terminal is electrically connected to a wiring supplying the column rewriting control signal, and whose output terminal is electrically connected to the second scan line;

a latch for driving the signal line and the second scan line, which is configured to retain a data signal supplied when a selection signal is input, and output the data signal;

a digital to analog converter circuit which is configured to convert the data signal output from the latch for driving the signal line and the second scan line into an analog data signal; and

an analog buffer which is configured to select, in accordance with an output signal of the AND gate, whether the analog data signal input from the digital to analog converter circuit is supplied to the signal line.

6. The display device according to claim 1,

wherein the controller comprises:

a frame memory which is configured to store data signals for forming images of a plurality of frames;

a comparator circuit which is configured to compare the data signals stored in the frame memory and forming images of successive two frames, and detect a difference;

a coordinate memory which is configured to store a coordinate data of a pixel in which the difference has been detected by the comparator circuit;

a data signal reading circuit which is configured to read a data signal from the frame memory and outputs the data signal to a signal line and second scan line driver circuit; and

a rewriting signal generation circuit which is configured to generate the column rewriting control signal and the row rewriting control signal on the basis of the coordinate data stored in the coordinate memory, and output the column rewriting control signal and the row rewriting control signal to the signal line and second scan line driver circuit and a first scan line driver circuit, respectively.

7. The display device according to claim 1, wherein each of the first transistor and the second transistor comprises an oxide semiconductor layer.

8. A display device comprising:

a controller configured to detect a difference in each of a plurality of pixels arranged in matrix by comparing data signals for forming images of successive two frames, and output a row rewriting control signal indicating whether the difference is detected in at least one of a first pixel to an n-th pixel (n is a natural number of two or more) arranged in the same row, and a column rewriting control signal indicating whether the difference is detected in a k-th pixel (k is a natural number more than or equal to one and less than or equal to n);

a first scan line which is electrically connected to the first pixel to the n-th pixel and to which a selection signal is supplied in accordance with the row rewriting control signal;

a second scan line which is electrically connected to pixels arranged in the same column as the k-th pixel and to which a selection signal is supplied in accordance with the column rewriting control signal; and

a signal line which is electrically connected to the pixels arranged in the same column as the k-th pixel and to which the data signals are supplied in accordance with the column rewriting control signal,

wherein the k-th pixel comprises;

a first transistor, a gate of which is electrically connected to the first scan line and one of a source and a drain of which is electrically connected to the signal line; and

a second transistor, a gate of which is electrically connected to the second scan line and one of a source and a drain of which is electrically connected to the other of the source and the drain of the first transistor.

9. The display device according to claim 8, further comprising:

a shift register for driving the first scan line, which is configured to sequentially output selection signals from output terminals in a first sampling period for driving the first scan line;

a first latch for driving the first scan line, which is configured to retain the row rewriting control signal supplied when a selection signal is input, and output the row rewriting control signal in a vertical retrace period following the first sampling period for driving the first scan line;

a second latch for driving the first scan line, which is configured to retain the row rewriting control signal input from the first latch for driving the first scan line, and output the row rewriting control signal in the vertical retrace period and a second sampling period for driving the first scan line following the vertical retrace period; and

a buffer configured to select, in accordance with the row rewriting control signal input from the second latch for driving the first scan line, whether a selection signal is supplied to the first scan line in a horizontal scan period included in the second sampling period for driving the first scan line.

10. The display device according to claim 8, further comprising:

a shift register for driving the first scan line, which is configured to sequentially output selection signals from output terminals; and

an AND gate whose first input terminal is electrically connected to any of the output terminals of the shift register for driving the first scan line, whose second input terminal is electrically connected to a wiring supplying the row rewriting control signal, and whose output terminal is electrically connected to the first scan line.

11. The display device according to claim 8, further comprising:

a shift register for driving the signal line and the second scan line, which is configured to sequentially output selection signals from output terminals in a first sampling period for driving the signal line and the second scan line;

a first latch for driving the signal line and the second scan line, which is configured to retain the column rewriting control signal supplied when a selection signal is input, and output the column rewriting control signal in a horizontal retrace period following the first sampling period for driving the signal line and the second scan line;

a second latch for driving the signal line and the second scan line, which is configured to retain the column rewriting control signal output from the first latch for driving the signal line and the second scan line, and output the column rewriting control signal to the second scan line in a horizontal scan period including the horizontal retrace period and a second sampling period for driving the signal line and the second scan line following the horizontal retrace period;

a third latch for driving the signal line and the second scan line, which is configured to retain a data signal supplied when a selection signal is input, and output the data signal in the horizontal retrace period;

a fourth latch for driving the signal line and the second scan line, which is configured to retain the data signal output from the third latch for driving the signal line and the second scan line, and outputs the data signal in the horizontal scan period;

a digital to analog converter circuit which is configured to convert the data signal output from the fourth latch for driving the signal line and the second scan line into an analog data signal; and

an analog buffer which is configured to select, in accordance with the column rewriting control signal, whether the analog data signal is supplied to the signal line in the horizontal scan period.

12. The display device according to claim 8, further comprising:

a shift register for driving the signal line and the second scan line, which is configured to sequentially output selection signals from output terminals;

an AND gate whose first input terminal is electrically connected to any of the output terminals of the shift register for driving the signal line and the second scan line, whose second input terminal is electrically connected to a wiring supplying the column rewriting control signal, and whose output terminal is electrically connected to the second scan line;

a latch for driving the signal line and the second scan line, which is configured to retain a data signal supplied when a selection signal is input, and output the data signal;

a digital to analog converter circuit which is configured to convert the data signal output from the latch for driving the signal line and the second scan line into an analog data signal; and

an analog buffer which is configured to select, in accordance with an output signal of the AND gate, whether the analog data signal input from the digital to analog converter circuit is supplied to the signal line.

13. The display device according to claim 8,

wherein the controller comprises:

a frame memory which is configured to store data signals for forming images of a plurality of frames;

a comparator circuit which is configured to compare the data signals stored in the frame memory and forming images of successive two frames, and detect a difference;

a coordinate memory which is configured to store a coordinate data of a pixel in which the difference has been detected by the comparator circuit;

a data signal reading circuit which is configured to read a data signal from the frame memory and outputs the data signal to a signal line and second scan line driver circuit; and

a rewriting signal generation circuit which is configured to generate the column rewriting control signal and the row rewriting control signal on the basis of the coordinate data stored in the coordinate memory, and output the column rewriting control signal and the row rewriting control signal to the signal line and second scan line driver circuit and a first scan line driver circuit, respectively.

14. The display device according to claim 8, wherein each of the first transistor and the second transistor comprises an oxide semiconductor layer.

15. A display device comprising:

a controller configured to detect a difference in each of a plurality of pixels arranged in matrix by comparing data signals for forming images of successive two frames, and output a row rewriting control signal indicating whether the difference is detected in at least one of a first pixel to an n-th pixel (n is a natural number of two or more) arranged in the same row, and a column rewriting control signal indicating whether the difference is detected in a k-th pixel (k is a natural number more than or equal to one and less than or equal to n);

a first scan line which is electrically connected to the first pixel to the n-th pixel and to which a selection signal is supplied in accordance with the row rewriting control signal;

a second scan line which is electrically connected to pixels arranged in the same column as the k-th pixel and to which a selection signal is supplied in accordance with the column rewriting control signal; and

a signal line which is electrically connected to the pixels arranged in the same column as the k-th pixel and to which the data signals are supplied in accordance with the column rewriting control signal,

wherein the k-th pixel comprises;

a first transistor, a gate of which is electrically connected to the first scan line and one of a source and a drain of which is electrically connected to the signal line;

a second transistor, a gate of which is electrically connected to the second scan line and one of a source and a drain of which is electrically connected to the other of the source and the drain of the first transistor; and

a display element which is electrically connected to the other of the source and the drain of the second transistor.

16. The display device according to claim 15, further comprising:

a shift register for driving the first scan line, which is configured to sequentially output selection signals from output terminals in a first sampling period for driving the first scan line;

a first latch for driving the first scan line, which is configured to retain the row rewriting control signal supplied when a selection signal is input, and output the row rewriting control signal in a vertical retrace period following the first sampling period for driving the first scan line;

a second latch for driving the first scan line, which is configured to retain the row rewriting control signal input from the first latch for driving the first scan line, and output the row rewriting control signal in the vertical retrace period and a second sampling period for driving the first scan line following the vertical retrace period; and

a buffer configured to select, in accordance with the row rewriting control signal input from the second latch for driving the first scan line, whether a selection signal is supplied to the first scan line in a horizontal scan period included in the second sampling period for driving the first scan line.

17. The display device according to claim 15, further comprising:

a shift register for driving the first scan line, which is configured to sequentially output selection signals from output terminals; and

an AND gate whose first input terminal is electrically connected to any of the output terminals of the shift register for driving the first scan line, whose second input terminal is electrically connected to a wiring supplying the row rewriting control signal, and whose output terminal is electrically connected to the first scan line.

18. The display device according to claim 15, further comprising:

a shift register for driving the signal line and the second scan line, which is configured to sequentially output selection signals from output terminals in a first sampling period for driving the signal line and the second scan line;

a first latch for driving the signal line and the second scan line, which is configured to retain the column rewriting control signal supplied when a selection signal is input, and output the column rewriting control signal in a horizontal retrace period following the first sampling period for driving the signal line and the second scan line;

a second latch for driving the signal line and the second scan line, which is configured to retain the column rewriting control signal output from the first latch for driving the signal line and the second scan line, and output the column rewriting control signal to the second scan line in a horizontal scan period including the horizontal retrace period and a second sampling period for driving the signal line and the second scan line following the horizontal retrace period;

a third latch for driving the signal line and the second scan line, which is configured to retain a data signal supplied when a selection signal is input, and output the data signal in the horizontal retrace period;

a fourth latch for driving the signal line and the second scan line, which is configured to retain the data signal output from the third latch for driving the signal line and the second scan line, and outputs the data signal in the horizontal scan period;

a digital to analog converter circuit which is configured to convert the data signal output from the fourth latch for driving the signal line and the second scan line into an analog data signal; and

an analog buffer which is configured to select, in accordance with the column rewriting control signal, whether the analog data signal is supplied to the signal line in the horizontal scan period.

19. The display device according to claim 15, further comprising:

a shift register for driving the signal line and the second scan line, which is configured to sequentially output selection signals from output terminals;

an AND gate whose first input terminal is electrically connected to any of the output terminals of the shift register for driving the signal line and the second scan line, whose second input terminal is electrically connected to a wiring supplying the column rewriting control signal, and whose output terminal is electrically connected to the second scan line;

a latch for driving the signal line and the second scan line, which is configured to retain a data signal supplied when a selection signal is input, and output the data signal;

a digital to analog converter circuit which is configured to convert the data signal output from the latch for driving the signal line and the second scan line into an analog data signal; and

an analog buffer which is configured to select, in accordance with an output signal of the AND gate, whether the analog data signal input from the digital to analog converter circuit is supplied to the signal line.

20. The display device according to claim 15,

wherein the controller comprises:

a frame memory which is configured to store data signals for forming images of a plurality of frames;

a comparator circuit which is configured to compare the data signals stored in the frame memory and forming images of successive two frames, and detect a difference;

a coordinate memory which is configured to store a coordinate data of a pixel in which the difference has been detected by the comparator circuit;

a data signal reading circuit which is configured to read a data signal from the frame memory and outputs the data signal to a signal line and second scan line driver circuit; and

a rewriting signal generation circuit which is configured to generate the column rewriting control signal and the row rewriting control signal on the basis of the coordinate data stored in the coordinate memory, and output the column rewriting control signal and the row rewriting control signal to the signal line and second scan line driver circuit and a first scan line driver circuit, respectively.

21. The display device according to claim 15, wherein each of the first transistor and the second transistor comprises an oxide semiconductor layer.

22. The display device according to claim 15, wherein the k-th pixel further comprises a capacitor which is electrically connected to the other of the source and the drain of the second transistor.