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US 6,310,600 B1Granted
Active matrix type device using forcible rewriting
AssigneeSemiconductor Energy Laboratory Co., Ltd.
InventorsJun Koyama, Yasuhiko Takemura
Life of this patent
Estimating the term…
Abstract
Power consumption is reduced by decreasing the frequency of image rewriting to pixels in displaying images which have a portion of a screen that does not vary between frames. On the other hand, to cope with the phenomenon that image information (for instance, pixel voltages) deteriorates over time, a refresh operation is performed regularly. Interlaced scanning is performed skipping a plurality of rows. The refresh operation is performed over several frames in which part of the rows are refreshed in one frame. A flicker is thus prevented which occurs when the entire screen is refreshed in one frame.
Claims27
An active matrix type device comprising:
- a pixel matrix;
- a refresh pulse generating circuit;
- a data comparison circuit which compares display data of continuous first and second frames in a same pixel of the pixel matrix and which sends a signal to the refresh pulse generating circuit when the display data of the continuous first and second frames in the same pixel are different from each other, the second frame subsequent to the first frame;
- and
- a plurality of thin film transistors each provided in a corresponding pixel and connected to a corresponding gate line at a gate electrode thereof,
- wherein a first refresh pulse is generated in the refresh pulse generating circuit to apply a gate pulse to the gate line of the same pixel when the display data of the continuous first and second frames in the same pixel are different from each other to rewrite the same pixel from the display data of the first frame to the display data of the second frame,
- wherein the refresh pulse generating circuit divides all of rows of the pixel matrix into N groups each consisting of m rows,
- wherein a second regular refresh pulse is generated in the refresh pulse generating circuit to apply a scanning signal to a gate electrode of the thin film transistor provided in a k-th row of each group in a k-th frame where k=1, 2, 3, . . . , m, and
- wherein the k-th row is forcibly rewritten in the k-th frame by the scanning signal.
6 more elements
An active matrix type device comprising:
- a pixel matrix;
- a plurality of pixel thin film transistors each provided in a corresponding pixel and connected to a corresponding gate line at a gate electrode thereof;
- a refresh pulse generating circuit;
- a data comparison circuit which compares display data of continuous first and second frames in a same pixel of the pixel matrix and which sends a signal to the refresh pulse generating circuit when the display data of the continuous first and second frames in the same pixel are different from each other, the second frame subsequent to the first frame;
- a gate driver;
- and
- an AND circuit provided between the gate driver and the corresponding gate line and having a first input terminal connected with said gate driver for inputting an output signal of the gate driver into the first input terminal, the AND circuit further having a second input terminal connected with the refresh pulse generating circuit, and the AND circuit further having an output terminal connected with the corresponding gate line,
- wherein a first refresh pulse is generated in the refresh pulse generating circuit to apply a gate pulse to the gate line of the same pixel when the display data of the continuous first and second frames in the same pixel are different from each other to rewrite the same pixel from the display data of the first frame to the display data of the second frame,
- wherein the refresh pulse generating circuit divides all of rows of the pixel matrix into N groups each consisting of m rows,
- wherein a second regular refresh pulse is generated in the refresh pulse generating circuit to apply a scanning signal to a gate electrode of the thin film transistor provided in a k-th row of each group in a k-th frame where k=1, 2, 3, . . . ,m, and
- wherein the k-th row is forcibly rewritten in the k-th frame by the scanning signal.
8 more elements
An active matrix type device comprising:
- a pixel matrix;
- a plurality of pixel thin film transistors each provided in a corresponding pixel and connected to a corresponding gate line at a gate electrode thereof;
- a refresh pulse generating circuit;
- a gate comparison circuit which compares display data of continuous first and second frames in a same pixel of the pixel matrix and which sends a signal to the refresh pulse generating circuit when the display data of the continuous first and second frames in the same pixel are different from each other, the second frame subsequent to the first frame;
- a gate driver comprising a third shift register;
- and
- an AND circuit provided between the third shift register and the corresponding gate line and having a first input terminal connected with said third shift register for inputting an output signal of the third shift register into the first input terminal, the AND circuit further having a second input terminal connected with the refresh pulse generating circuit, and the AND circuit further having an output terminal connected with the corresponding gate line,
- wherein a first refresh pulse is generated in the refresh pulse generating circuit to apply a gate pulse to the gate line of the same pixel when the display data of the continuous first and second frames in the same pixel are different from each other to rewrite the same pixel from the display data of the first frame to the display data of the second frame,
- wherein the refresh pulse generating circuit divides all of rows of the pixel matrix into N groups each consisting of m rows,
- wherein a second regular refresh pulse is generated in the refresh pulse generating circuit to apply a scanning signal to a gate electrode of the thin film transistor provided in a k-th row of each group in a k-th frame where k=1, 2, 3, . . . , m, and
- wherein the k-th row is forcibly rewritten in the k-th frame by the scanning signal.
8 more elements
An active matrix type device comprising:
- a pixel matrix;
- a plurality of pixel thin film transistors each provided in a corresponding pixel and connected to a corresponding gate line at a gate electrode thereof;
- a compensation circuit for compensating a video signal to be applied to a source of the pixel thin film transistor to prevent display performance from differing among the pixels;
- a refresh pulse generating circuit;
- and
- a data comparison circuit which compares display data of continuous first and second frames in the same pixel of the pixel matrix and which sends a signal to the refresh pulse generating circuit when the display data of the continuous first and second frames in the same pixel are different from each other, the second frame subsequent to the first frame,
- wherein a first refresh pulse is generated in the refresh pulse generating circuit to apply a gate pulse to the gate line of the same pixel when the display data of the continuous first and second frames in the same pixel are different from each other to rewrite the same pixel from the display data of the first frame to the display data of the second frame,
- wherein the refresh pulse generating circuit divides all of rows of the pixel matrix into N groups each consisting of m rows,
- wherein a second regular refresh pulse is generated in the refresh pulse generating circuit to apply a scanning signal to a gate electrode of the thin film transistor provided in a k-th row of each group in a k-th frame where k=1, 2, 3, . . . , m, and
- wherein the k-th row is forcibly rewritten in the k-th frame by the scanning signal.
7 more elements
Dependencies are inferred from the claim text.