Active matrix display and a method of driving the same
First Claim
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1. A method of driving an active matrix display with a plurality of gradation levels, wherein the maximum number of gradation level is Nmax=(1+21+ - - - 2k) l, k, and l each being a natural number, said method comprising the steps of:
- providing said active matrix display wherein said display has a plurality of thin film transistors for switching a plurality of pixels of the display;
inputting into a pixel of said display one or more pulses, each pulse having a pulse height and a pulse duration depending upon a desired gradation level of the display at said pixel, wherein each of said one or more pulses has a relative pulse duration selected from the group consisting of 1, 2, - - - 2k and has a relative pulse height selected from the group consisting of 0, 1, 2, - - - I so that the pulse duration and the pulse height of said pulses are both varied whereby the minimum width of said pulses can be increased.
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Abstract
For a gradation displaying operation for an electro-optical device, a gradation display system which can be controlled by a digital signal and is hard to be affected by variation in characteristics between respective elements and which can achieve high gradation, is provided. In the active matrix type electro-optical device, by the digital control of time and amplitude of a voltage pulse applied to each picture element electrode, composite pulses having plural voltage values and pulse widths are formed for one frame of an image so that an average effective voltage of the one frame of the image is made an arbitrary value, thereby finally displaying an intermediate color tone on liquid crystal.
21 Citations
23 Claims
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1. A method of driving an active matrix display with a plurality of gradation levels, wherein the maximum number of gradation level is Nmax=(1+21+ - - - 2k) l, k, and l each being a natural number, said method comprising the steps of:
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providing said active matrix display wherein said display has a plurality of thin film transistors for switching a plurality of pixels of the display;
inputting into a pixel of said display one or more pulses, each pulse having a pulse height and a pulse duration depending upon a desired gradation level of the display at said pixel, wherein each of said one or more pulses has a relative pulse duration selected from the group consisting of 1, 2, - - - 2k and has a relative pulse height selected from the group consisting of 0, 1, 2, - - - I so that the pulse duration and the pulse height of said pulses are both varied whereby the minimum width of said pulses can be increased. - View Dependent Claims (2, 3, 4, 5, 6, 7, 9)
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8. A method of driving an active matrix display with a plurality of gradation levels, wherein the maximum number of gradation level is Nmax where Nmax=(1+21+ - - - 2k) I, k and I each being a natural number, said method comprising the steps of:
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providing said active matrix display wherein a plurality of thin film transistors disposed on said display respectively drive a plurality of pixels of the display;
storing in a memory gradation level data in which each level from 0 to N is assigned with one or more pulses determined in accordance with an equation;
- View Dependent Claims (10, 11, 12, 13, 14, 15)
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16. A method of driving an active matrix display device, comprising:
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applying a plurality of pulses during one frame to a pixel, wherein the pulse duration of n-th pulses is 2(n−
1)T0 (where T0 is a constant and n is a natural number) and a level of the respective pulses is selected from at least two predetermined levels, and a number of the pulses applied during said one frame to the pixel, said pulse duration and said level are decided in accordance with a desired tone of the pixel,wherein said pixel is provided with at least one thin film transistor for switching said pixel. - View Dependent Claims (17, 18, 19)
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20. An active matrix display device comprising:
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a plurality of pixels arranged in a matrix, each of the pixels provided with at least one thin film transistor for switching;
a driver circuit for driving the thin film transistors; and
a signal processor operationally connected to said driver circuit to output a plurality of pulses during one frame for one of the pixels, wherein the pulse duration of n-th pulses is 2(n−
1)T0(where T0 is a constant and n is a natural number) and a level of the respective pulses is selected from at least two predetermined levels, and a number of the pulses applied during said one frame to the pixel, said pulse duration and said level are decided in accordance with a desired tone of the pixel.- View Dependent Claims (21, 22, 23)
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Specification
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Current AssigneeSemiconductor Energy Laboratory Co., Ltd.
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Original AssigneeSemiconductor Energy Laboratory Co., Ltd.
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InventorsHiroki, Masaaki, Takemura, Yasuhiko, Yamazaki, Shunpei
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Primary Examiner(s)AWAD, AMR A
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Application NumberUS09/592,267Time in Patent Office1,526 DaysField of Search345/89, 345/90, 345/208, 345/92, 345/210, 345/690, 345/691, 345/692, 345/694US Class Current345/89CPC Class CodesG09G 3/2011 by amplitude modulationG09G 3/2022 using sub-framesG09G 3/2081 with combination of amplitu...G09G 3/22 using controlled light sourcesG09G 3/3648 using an active matrix G09G...
