Liquid-crystal halftone display system

• US 6,542,141 B1
• Filed: 06/06/2000
• Issued: 04/01/2003
• Est. Priority Date: 10/01/1991
• Status: Expired due to Fees

• Current Assignee: Panasonic Liquid Crystal Display Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Hitachi, Ltd.
• Inventors: Tanaka, Toshio, Kasai, Naruhiko, Takahashi, Kohji, Furuhashi, Tsutomu, Mano, Hiroyuki, Nishitani, Shigeyuki, Futami, Toshio, Mega, Masaki, Kitajima, Masaaki
• Primary Examiner(s): Saras, Steven
• Assistant Examiner(s): BELL, PAUL A
• Application Number:
  US09/588,048
• Time in Patent Office: 1,029 Days
• Field of Search: 345/89, 345/690, 345/691, 345/692, 345/693, 345/210, 345/94, 345/95, 345/694, 345/696
• US Class Current: 345/89
• CPC Class Codes: G09G 2320/0247 Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
• CPC Class Codes: G09G 3/2018 by time modulation using two or more time intervals
• CPC Class Codes: G09G 3/3622 using a passive matrix G09G3/3674 - G09G3/3696 take precedence

Abstract

A liquid crystal halftone display system including a tone generator which, for pixels having P tones of K tones (1≦P≦K), alternately outputs first N-bit tone display data and second N-bit tone display data in successive frames at one of a first phase and a second phase. Within a block of pixels, the tone generator alternately inverts the phase of the N-bit tone display data at successive first pixels having different ones of the P tones within the block of pixels beginning at a left side of the block of pixels, and alternately inverts the phase of the N-bit tone display data at successive pixels having a same one of the P tones within the block of pixels beginning at the left side of the block of pixels.

Claims

1. A liquid crystal halftone display system comprising:

a liquid crystal panel including a plurality of pixels disposed in a plurality of lines;

a tone generator which

receives L-bit input display data for each of the pixels, the L-bit input display data representing one of K=2^L tones,

generates N-bit tone display data (N<

L) for each of the pixels based on the L-bit input display data for each of the pixels, the N-bit tone display data representing one of M=2^N tones (M<

K), and

outputs the N-bit tone display data for each of the pixels in each of a plurality of frames, the plurality of frames constituting one display image; and

a data driver which

receives the N-bit tone display data from the tone generator,

generates a tone voltage for each of the pixels based on the N-bit tone display data, and

outputs the tone voltage for each of the pixels;

wherein the liquid crystal panel

receives the tone voltage for each of the pixels from the data driver, and

displays an M-tone image in each of the plurality of frames constituting one display image in response to the tone voltage for each of the pixels, thereby displaying a K-tone image over the plurality of frames constituting one display image;

wherein for pixels having P tones of the K tones (1≦

P≦

K), the tone generator alternately outputs first N-bit tone display data and second N-bit tone display data in successive frames at one of a first phase and a second phase, the second N-bit tone display data being different from the first N-bit tone display data, the first phase being a phase in which the tone generator outputs the first N-bit tone display data in a current frame and outputs the second N-bit tone display data in a succeeding frame, and the second phase being a phase in which the tone generator outputs the second N-bit tone display data in the current frame and outputs the first N-bit tone display data in the succeeding frame;

wherein for pixels having K−

P tones of the K tones, the tone generator outputs N-bit display data which is the same in successive frames;

wherein each of the lines contains a plurality of blocks of pixels, a number of pixels in each of the blocks of pixels being less than a number of pixels in one line; and

wherein within each of the blocks of pixels, the tone generator

alternately inverts the phase of the N-bit tone display data at successive first pixels having different ones of the P tones within the block of pixels beginning at a left side of the block of pixels, and

alternately inverts the phase of the N-bit tone display data at successive pixels having a same one of the P tones within the block of pixels beginning at the left side of the block of pixels.

2. A liquid crystal halftone display system according to claim 1, wherein L=4 and N=3.

3. A liquid crystal halftone display system according to claim 1, wherein the tone generator includes a table which specifies combinations of the first N-bit tone display data and the second N-bit tone display data for each of the P tones.

4. A liquid crystal halftone display system according to claim 3, wherein the table stores each of the combinations of the first N-bit tone display data and the second N-bit tone display data in association with a corresponding one of the L-bit input display data in a table entry for the corresponding one of the L-bit input display data.

5. A liquid crystal halftone display system according to claim 1, wherein the number of pixels in each of the blocks of pixels is 16.