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EP0646906A2 Expired / Lapsed EP ⏱️ 0.0 years remaining

Method and apparatus for driving a display device

Assignee: International Business Machines Corp
•
Filing: 1994-09-29
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Granted: —
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Expires: 2014-09-29
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Abstract

Abstract In order to be able to accurately display an image which is represented by image data, even if a display device can express only a small number of gradations, frame rate modulation is used. The image data, which express a density of one dot by 4-bit dot data, is converted into a plurality of frame data, which express a density of one dot by 3 bits, so that the plurality of the frame data are sequentially displayed on the LCD. In the above conversion, the three most significant bits of the dot data are extracted to operate data of one dot of each frame. If the least significant bit of the first dot data is 1 and the most significant bit is 0, then 1 is added to a corresponding portion of the respective frame data. If, on the other hand, the least significant bit of the dot data is 0 and the most significant bit is 1, then 1 is subtracted from a corresponding portion of the respective frame data. In accordance with the above description, the image data is converted into the frame data as shown in Table 2, and the sum (apparent densities) of the plurality of converted frame data always changes in accordance with the changes in the dot data.

Inventors

  • 👤 Masanori Kusano
  • 👤 Masaki Oie
  • 👤 Eisuke Kanzaki

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-11-09 12:38
CPC Classifications
G; G09; G09G; G09G3/00; G09G3/20; G09G3/34; G09G3/36; G09G3/3611; G09G3/3648; G09G3/2007; G09G3/2018

Claims Analysis

Total Claims: 6
Claim 1
Independent Claim 185 words
A method for driving a liquid crystal display device in which image data, which expresses respective densities of dots by first dot data of a predetermined bit length, is converted into a plurality of frame data, which expresses respective densities of dots by second dot data which is shorter than said predetermined bit length, so as to drive a display device by said plurality of frame data, the method being characterized by converting image data into a plurality of frame data by using data, from which a least significant bit of said first dot data has been removed, to generate said respective second dot data of said plurality of frame data, and in a case in which the least significant bit of said first dot data is 1 and a most significant bit is 0, adding 1 to a corresponding portion of said plurality of second dot data, and in a case in which the least significant bit of said first dot data is 0 and the most significant bit is 1, subtracting 1 from a corresponding portion of said plurality of second dot data.
Claim 2
Dependent Claim 92 words
A display device driving method according to Claim 1, wherein in a case in which a difference between one of said first dot data and a first dot data whose most significant bit of said first dot data is 1 and the other bits are 0 is small, a number of second dot data for which said addition or said subtraction is effected is decreased, and in a case in which said difference is large, the number of second dot data for which said addition or said subtraction is effected is increased.
Claim 3
Dependent Claim 34 words
A display device driving method according to any of the preceding claims, wherein a liquid-crystal display at which a thin-film transistor is provided in correspondence with respective dots is used as said display device.
Claim 4
Dependent Claim 21 words
A display device driving method according to any of the preceding claims, wherein image data is converted into three frame data.
Claim 5
Dependent Claim 195 words
Apparatus for driving a liquid crystal device in which image data, which expresses respective densities of dots by first dot data of a predetermined bit length, is converted into a plurality of frame data, which expresses respective densities of dots by second dot data which is shorter than said predetermined bit length, so as to drive a display device by said plurality of frame data, said apparatus being characterised in that it is adapted to convert image data into a plurality of frame data by using data, from which a least significant bit of said first dot data has been removed, to generate said respective second dot data of said plurality of frame data, and in that it is adapted to add 1 to a corresponding portion of said plurality of second dot data, in the case in which the least significant bit of said first dot data is 1 and a most significant bit is 0, and to subtract 1 from a corresponding portion of said plurality of second dot data, in the case in which the least significant bit of said first dot data is 0 and the most significant bit is 1.
Claim 6
Dependent Claim 20 words
Portable computer including a liquid crystal display and apparatus for driving said liquid crystal display, as claimed in claim 5.

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