Method for driving matrix type flat panel display device

• US 5,602,559 A
• Filed: 02/15/1995
• Issued: 02/11/1997
• Est. Priority Date: 11/01/1991
• Status: Expired due to Term

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fuji Photo Film Co Limited (Fujifilm Holdings Corporation)
• Inventors: Kimura, Koichi
• Primary Examiner(s): SARAS, STEVEN J
• Application Number:
  US08/389,741
• Time in Patent Office: 727 Days
• Field of Search: 345/89, 345/94, 345/97, 345/98, 345/99, 345/100, 345/148, 359/56
• US Class Current: 345/89
• CPC Class Codes: G09G 2310/0205 Simultaneous scanning of several lines in flat panels
• CPC Class Codes: G09G 2310/06 Details of flat display driving waveforms
• CPC Class Codes: G09G 2310/061 for resetting or blanking
• 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 3/3629 using liquid crystals having memory effects, e.g. ferroelectric liquid crystals

Abstract

There is provided a method of driving a matrix type flat panel display device, by which the selection time 2τ can be set to a longer time as compared to the prior art frame period shortened scanning method wherein the scanning line are divided into plural groups. One frame period T_f includes plural fields, at least one of the fields has a number of blocks different from the block numbers of other fields, all scanning lines are also divided into a number of groups so that the number of divided scanning line groups is at least equal to the total block numbers included in each frame period, the writing time period included in the first block of each field having a time period including selection time periods for all fields so that the selection time period for each field does not overlap with the selection time periods for other fields. Flicker is prevented by an interlace scanning along the scanning lines of respective groups in such a manner that the fields having the same graduation level are not scanned one after another in the direction cross to the scanning lines at right angle.

Claims

1. A method for driving a matrix type flat panel display device comprising a matrix of scanning electrodes and signal electrodes intersecting with each other, so that a bistable display picture element is formed at each region of intersection between said scanning and signal electrodes, each said picture element being adapted to be set in either of bright or dark states so as to achieve a multi-graduation display, said method comprising the steps of:

defining a frame period T_f to include plural fields, with each field composed of one or more blocks so that at least one of said fields has a number of blocks different from the numbers of blocks of other fields,

dividing a plurality of scanning lines into groups so that the number of divided scanning line groups is at least equal to the total number of blocks included in said frame period T_f, and

setting writing time periods included in a first block of each field to have time periods that include selection time periods so that the selection time periods for each divided scanning line group do not overlap with the selection time periods for other groups even though the writing time periods overlap with writing time periods for at least one other group.

2. The method of claim 1, wherein said frame period T_f includes N fields, wherein the number of blocks included in respective fields is given by 2ⁿ, where n stands for 0, . . . 1, . . . , N-1, respectively, and wherein said plurality of scanning lines is equally divided into (2^N -1) groups, whereby said method achieves a multi-graduation display of 2^N levels.

3. The method of claim 2, wherein a number Y, representing a total number of said scanning lines, is changed to an imaginary number Z which is equal to the least multiple number of (2^N -1) that is larger than an actual number of scanning lines provided by the display device.

4. The method of claim 2, wherein a number Y, representing a total number of said scanning lines, is equally divided by a number L, where L is the least divisor of the number Y that is larger than (2^N -1), and wherein said frame period T_f is divided into L blocks and the remaining (L-(2^N -1)) blocks are used as reset time periods for said frame period T_f.

5. The method of claim 2, wherein scanning operation is performed such that the scanning lines for different groups are scanned in an interlacing fashion so that the fields having the same graduation level are not overlapped with each other in the direction cross to the scanning lines at right angle.

6. The method of claim 5, wherein the phase of the signal of each scanning line is shifted by about 180°

from the phase of the signal of adjacent scanning line.

7. The method of claim 1, wherein said flat panel display device is a display panel composed of a ferroelectric liquid crystal.

8. The method of claim 2, wherein said flat panel display device is a display panel composed of a ferroelectric liquid crystal.

9. The method of claim 3, wherein said flat panel display device is a display panel composed of a ferroelectric liquid crystal.

10. The method of claim 4, wherein said flat panel display device is a display panel composed of a ferroelectric liquid crystal.

11. The method of claim 5, wherein said flat panel display device is a display panel composed of a ferroelectric liquid crystal.

12. The method of claim 6, wherein said flat panel display device is a display panel composed of a ferroelectric liquid crystal.