Method of gray scale display for dot matrix type display device

• US 5,266,940 A
• Filed: 01/27/1992
• Issued: 11/30/1993
• Est. Priority Date: 03/05/1988
• Status: Expired due to Term

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Shiraishi, Tai
• Primary Examiner(s): Oberley, Alvin E.
• Assistant Examiner(s): SARAS, STEVEN J
• Application Number:
  US07/825,330
• Time in Patent Office: 673 Days
• Field of Search: 340/703, 340/784, 340/793, 340/767, 340/783, 340/774, 340/775, 340/771, 358/240
• US Class Current: 345/696
• CPC Class Codes: G09G 3/2025 the sub-frames having all the same time duration
• CPC Class Codes: G09G 3/2051 with use of a spatial dither pattern
• CPC Class Codes: G09G 3/2077 by a combination of two or more gradation control methods
• CPC Class Codes: H04N 3/12 by switched stationary formation of lamps, photocells or light relays

Abstract

A method for displaying a gray scale on a dot matrix type display device divides picture elements on a screen of the display device into partitions with N picture elements per partition. The picture elements correspond to (N+1) degrees of the gray scale display in which a binary level display signal is generated for representing a lighting and a lighting status. The method also upon setting each picture element to a desired degree of the gray scale display, provides that adjacent picture elements, at least in the same partition, have different phases with respect to the gray scale display. The picture elements arrayed at the same position in each partition have the same phase with respect to the gray scale display when their degree is the same.

Claims

1. A method for generating a gray scale display in a dot matrix type display device comprising the steps of:

(a) dividing picture elements on a screen of the display device into a plurality of partitions, each partition having N number of picture elements and dividing each of said plurality of partitions into a plurality of picture element groups, each picture element group having at least N/4 number of picture elements, said picture elements corresponding to N degrees of the gray scale display in which a binary level signal is generated for each picture element to represent a lighting and non-lighting state;

(b) setting each of the plurality of partitions to a desired degree of gray scale display, M;

(c) generating a lighting pattern corresponding to the desired degree of gray scale display, M, for a plurality of frames, wherein the lighting pattern has M picture elements in the lighting state for each of the plurality of frames, wherein the lighting pattern varies for each picture element group for successive frames in the plurality of frames;

(d) providing the lighting pattern to the plurality of partitions for the plurality of frames to produce the gray scale display;

wherein the lighting pattern has an equal number of pixels in the lighting state for each of the plurality of pixel element groups over at most N/4 frames.

2. The method as claimed in claim 1 wherein each partition, when providing a 16-gray scale display, is comprised of 4 rows and 4 columns of picture elements.

3. The method as claimed in claim 1 wherein each partition, when providing an 8-gray scale display, is comprised of 2 rows and 4 columns of picture elements.