Half-tone representation system and controlling apparatus therefor

• US 5,309,170 A
• Filed: 04/26/1990
• Issued: 05/03/1994
• Est. Priority Date: 04/28/1989
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd., Hitachi Video Engineering Incorporated
• Original Assignee: Hitachi, Ltd., Hitachi Video Engineering Incorporated
• Inventors: Jinushi, Masahiro, Kouchiyama, Kazuya, Takashi, Terumi
• Primary Examiner(s): Oberley, Alvin E.
• Assistant Examiner(s): Mengistu, Amare
• Application Number:
  US07/514,591
• Time in Patent Office: 1,468 Days
• Field of Search: 340/793, 340/703, 340/701, 345/88, 345/89
• 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 3/3607 for displaying colours or for displaying grey scales with a specific pixel layout, e.g. using sub-pixels display of colours in flat matrix panels other than liquid crystal displays G09G3/2003; grey scales specific for television H04N3/127
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers

Abstract

A half-tone color representation system suitable for use with a multi-color liquid crystal display panel, each display dot of which is constituted by three primary color pixels. More than eight different colors are represented with the three primary color pixels by providing a "half-tone" state of a pixel which is realized through successive ON-OFF controlling of the pixel. Flicker in the half-tone color representation of the display dot is reduced by causing the patterns or timings of successive ON-OFF controlling of the three primary color pixels to be different from one another.

Claims

1. A half-tone representation system for displaying data on a display in which each display dot is constituted by a set of N color pixels, where N is an integer of three or more, each pixel capable of being ON-OFF controlled to provide a predetermined number of different colors depending on the combination of ON and OFF states of the N color pixels, the half-tone representation system comprising means for controlling said display to provide an increased number with respect to the predetermined number of different colors by successively ON-OFF controlling any one or more of said N color pixels in a half-tone state according to a predetermined repetitive ON-OFF pattern in successive frames, and means for causing, when at least two of the N color pixels are in the half-tone state, the predetermined repetitive ON-OFF patterns for the at least two or the N color pixels to be different in phase from one another.

2. A half-tone representation controlling apparatus for controlling the display of display data on a color display panel which has display dots each being constituted by a set of N color pixels, where N is an integer of three or more, each of the pixels being capable of being ON-OFF controlled, the half-tone representation controlling apparatus comprising:

a frame counter for counting the number of display frames of the color display panel;

N half-tone signal generators each for producing an "ON" signal during a time when the count of said frame counter is a predetermined value or values which are different for each of the N half-tone signal generators; and

a control circuit responsive to the display data which represents a half-tone color for outputting selected part or all of the half-tone signals to said color display panel in place of a part or all of said display data.

3. A half-tone representation controlling apparatus according to claim 2, wherein each of said N half-tone signal generators has a separate frame counter connected thereto.

4. A half-tone representation controlling apparatus according to claim 3, wherein maximum counts and said predetermined values of the separate frame counters are set such that a proportion of lightnesses of said N color pixels all in "ON" states are equal to that of lightnesses of said N color pixels all in "half-tone" states.

5. A system having color display panel for display data in colors, comprising:

a multitude of display dots disposed on the color display panel, each of the display dots being constituted by a set of N color pixels each capable of being ON-OFF controlled, where N is an integer of three or more;

a half-tone representation controlling apparatus built in the color display panel, and including;

a frame counter for counting the number of display frames of the color display panel;

N half-tone signal generators each of producing an "ON" signal during a time when the count of said frame counter is a predetermined value or values which are different from each of the N half-tone signal generators; and

a control circuit responsive to the display data which represents a half-tone color for outputting selected part of all of the half-tone signals to said color display panel in place of a part or all of said display data.

6. A system according to claim 5, wherein each of said N half-tone signal generators has a separate frame counter connected thereto.

7. A system according to claim 5, wherein maximum counts and said predetermined values of the separate frame counters are set such that a proportion of lightness of said N color pixels all in "ON" states are equal to that of lightness of said N color pixels all in "half-tone" states.

8. A half-tone representation system for displaying data on a display in which each display dot is constituted by a set of N color pixels, where N is an integer of three or more, each pixel capable of being ON-OFF controlled to provide a predetermined number of different colors depending on the combination of ON and OFF states of the N color pixels, the half-tone representation system comprising means for controlling said display to provide an increased number with respect to the predetermined number of different colors by successively ON-OFF controlling any one or more of said N color pixels in a half-tone state in successive frames, and means for inhibiting, when at least two of the N color pixels are in the half-tone state, the at least two of the N color pixels from being in the ON state simultaneously.

9. A half-tone representation system for displaying data on a display in which each display dot is constituted by a set of N color pixels, where N is an integer of three or more, each pixel capable of being ON-OFF controlled in response to N bits of display data for displaying colors, the half tone representation system comprising:

means for inputting an (N+1)-th bit of display data;

means for generating N half-tone signals, each of the N half-tone signals having a predetermined repetitive ON-OFF pattern including a combination of ON and OFF states, each of the N half-tone signals being different in phase from one another; and

means for replacing one or more of the N bits of display data which are in an OFF state by a respective half-tone signal in dependence upon a state of the (N+1)-th bit of display data.

10. A half-tone representation system for displaying data on a display in which each display dot is constituted by a set of N color pixels, where N is an integer of three or more, each pixel capable of being ON-OFF controlled to provide a predetermined number of different colors depending on the combination of ON and OFF states of the N color pixels, the half-tone representation system comprising means for controlling said display to provide an increased number with respect to the predetermined number of different colors by a frame thinning operation of any one or more of said N color pixels in successive frames so that when two or more of the N color pixels under the frame thinning operation are controlled, the two or more of the N color pixels do not change to an ON state in the same frame.

11. A system according to claim 10, wherein the means for controlling controls the rates of the frame thinning of the N color pixels to be different from one another.