Display control device for use with flat-panel display and color CRT display

• US 5,491,496 A
• Filed: 05/02/1994
• Issued: 02/13/1996
• Est. Priority Date: 07/31/1991
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation), Toshiba Corporation
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Tomiyasu, Yuichi
• Primary Examiner(s): Kunta, Curtis
• Assistant Examiner(s): HARVEY, MINSUN OH
• Application Number:
  US08/237,711
• Time in Patent Office: 652 Days
• Field of Search: 345/3, 345/22, 345/153, 345/199, 345/147, 345/89, 345/186, 345/150
• US Class Current: 345/690
• CPC Class Codes: G06F 3/1475 with conversion of CRT control signals to flat panel control signals, e.g. adapting the palette memory
• CPC Class Codes: G09G 2320/0276 for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction
• CPC Class Codes: G09G 5/028 Circuits for converting colour display signals into monochrome display signals
• CPC Class Codes: G09G 5/06 using colour palettes, e.g. look-up tables

Abstract

In the interlocking mode, the color of the color data is converted into a brightness value by a brightness converting circuit in accordance with the value of each of R, G, B of the color data written into each color register of RAMDAC. Gradation data to be written into each register of the flat palette table is formed from the brightness value. In the non-interlocking mode, an optional gradation data irrelevant to the color data of the RAMDAC is written into each register of the flat palette table. By the switching between interlocking and non-interlocking modes, selection can be made between the monochrome gradation display which faithfully reproduces the color display screen of a CRT display and the monochrome display of an optional gradation irrelevant to the color display screen.

Claims

1. A display control device for controlling a color CRT display and a monochrome flat-panel display with 2^m gradations, comprising:

color table means having a plurality of color registers for holding color data for one pixel of said color CRT display, one of said color registers being selected by display data having color information;

supply means for converting R, G, B color data held by the selected register of the color table means into analog color video signals and for supplying the converted video signals to said color CRT display;

summing-colors-to-gray-scale means for converting the intensity value found for each of the color data R, G, and B written into the selected color registers of the color table means into its corresponding gray scale value of n bits (n>

m);

forming means for adding a predetermined value to first gradation data represented by the high-order m bits of the n-bit gray scale value (n>

m) converted by the summing-colors-to-gray-scale means so as to form a set of second gradation data of m bits;

selecting means connected to each of said set of forming means and said flat panel display for selecting one of said first gradation data and said set of second gradation data in accordance with a select signal for each of a plurality of dots constituting one pixel of a flat panel display device and for supplying the selected data to said flat panel display; and

select signal generating means connected to said selecting means for generating said select signal denoting assignment of the selected data to said plurality of dots in accordance with the value of the low-order n-m bits of the first gradation data.

2. The display control device according to claim 1, wherein said select signal generating means comprises means connected to said selecting means for selectively generating 2(^n-m) different gradation patterns each indicating assignment of the first or second gradation data for said plurality of dots in accordance with the value of the lower-order (n-m) bits of the first gradation data and for controlling the generation of said select signal in accordance with the generated gradation pattern.

3. A display control device for use with a color CRT display and a color flat-panel display device which has 2^m gradations for each of colors R, G, and B, comprising:

color table means having a plurality of color registers for holding R, G, B color data for said color CRT display, one of said plurality of color registers being selected by display data having a color information;

means connected to said color table means for converting said R, G, B color data from said color table means into analog color video signals and for supplying the converted analog color video signals to said color CRT display; and

video data forming means connected to said color table means for receiving said R, G, B color data each consisting of n bits (n>

m) and held by the selected register of the color table means and for forming R, G, B color video data based on the received color data, said color video data being supplied to said color flat panel display device;

each of said video data forming means comprising;

means connected to said color table means for adding a predetermined value to first color data represented by the high-order m-bits of the color data for the corresponding color consisting of n bits (n>

m) and held in the selected register of the color table means so as to form second color data;

select means connected to said color flat panel display device for selecting one of said first and second color data in accordance with a select signal indicating selection of said first or second color data for each of a plurality of dots constituting one pixel of said color flat panel display device and for supplying the selected color data to said color flat panel display device; and

select signal generating means connected to said color table means for generating said select signals each indicating the assignment of said first or second color data for said plurality of dots in accordance with the value of the low order (n-m) bits of the color data consisting of n bits (n>

m).

4. The display control device according to claim 3, wherein said select signal generating means comprises means connected to said color table means for selectively generating 2(^n-m) different gradation patterns each indicating the assignment of the first or second color data for said plurality of dots in accordance with the value of the low-order (n-m) bits of the color data consisting of n bits (n>

m) and for controlling the generation of the select signal in accordance with the generated gradation pattern.

5. A display control device, comprising:

color table means having a plurality of color registers for holding R, G, B color data for a color CRT display, one of said plurality of color registers being selected by display data having color information;

means connected to said color table means for converting said R, G, B color data output from said color table means into analog color video signals and for supplying the converted analog color video signals to said color CRT display;

summing-colors-to-gray scale means for converting an intensity value found for each of the color data R, G, B written into the selected color register of the color table means into its corresponding gray scale value having a plurality of bits; and

conversion table means connected to said summing-colors-to-gray-scale means for converting the gray scale value converted by said summing-colors-to-gray-scale means into gradation data having fewer bits than that of the gray scale value and for supplying the gradation data to a flat panel display device,

wherein said conversion table means comprises;

a conversion table having a plurality of registers for holding gradation data of predetermined bits; and

means for selectively outputting the gradation data stored in one of the registers of the conversion table in accordance with said gray scale value.

6. The display control device according to claim 5, wherein said conversion table means comprises a writable memory for holding the gradation data of the predetermined bits and means for means for changing the gradation data in the writable memory.

7. A display control device, comprising:

color table means having a plurality of color registers for holding R, G, B color data for a color CRT display, one of said plurality of color registers being selected by display data having color information;

means connected to said color table means for converting said R, G, B color data output from said color table means into analog color video signals and for supplying the converted analog color video signal to said color CRT display;

summing-colors-to-gray scale means for converting an intensity value found for each of the color data R, G, B written into the selected color register of the color table means into its corresponding gray scale value, the summing-colors-to-gray-scale means comprising means for multiplying constants 0.30, 0.59, and 0.11 by R-data, G-data and B-data, respectively, representing the data output from said color table means, and for adding the multiplied results to obtain a combined gray scale value having a plurality of bits; and

conversion table means connected to said summing-colors-to-gray-scale means for converting the combined gray scale value converted by said summing-color-to-gray-scale means into gradation data having fewer bits than those of the combined gray scale value and for supplying the gradation data to a flat panel display device.