Display control apparatus

• US 5,977,945 A
• Filed: 09/25/1997
• Issued: 11/02/1999
• Est. Priority Date: 09/18/1991
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Ohshima, Masamichi
• Primary Examiner(s): CHOW, DOON Y
• Application Number:
  US08/936,997
• Time in Patent Office: 768 Days
• Field of Search: 345/87, 345/97, 345/98, 345/99, 345/100, 345/55, 345/507, 345/515, 345/516, 348/792, 348/793
• US Class Current: 345/100
• CPC Class Codes: G09G 2310/04 Partial updating of the display screen
• CPC Class Codes: G09G 2320/0247 Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
• CPC Class Codes: G09G 3/3629 using liquid crystals having memory effects, e.g. ferroelectric liquid crystals
• CPC Class Codes: G09G 3/3651 using multistable liquid crystals, e.g. ferroelectric liquid crystals

Abstract

A display control apparatus includes display device driver means for writing image information into a frame buffer, and display scanning means for sequentially displaying the image data stored in the frame buffer for each line of the display. The display control apparatus further includes partially rewritten line determination means for obtaining from the display device driver means information regarding lines to be written into the frame buffer, and generating in accordance therewith the lines for which the display is to be scanned, and display scan line control means for obtaining from the partially rewritten line determination means lines to be scanned to specify such lines for the display scanning means.

Claims

1. An apparatus for performing a raster scanning display operation on a display including a plurality of scanning lines, comprising:

storing means for storing image data to be displayed;

updating means, including a program, for performing an updating operation to update a portion of the image data stored in the storing means to different, updated image data, the updated image data being determined by said updating means using a command of the program; and

drive means for driving the display to perform the display operation in accordance with the updated image data,

wherein said updating means performs the updating operation without accessing the previously stored image data and simultaneously supplies line information designating one of the scanning lines on which to display the updated data to said drive means.

2. An apparatus according to claim 1, wherein said image data is generated in accordance with a command of application software.

3. A display apparatus according to claim 2, wherein the display is a ferroelectric liquid crystal display.

4. An apparatus according to claim 1, wherein said updating means executes processing for supplying said line information with software of a central arithmetic processing unit and of a graphic controller.

5. An apparatus according to claim 1, wherein said drive means sequentially selects a plurality of scanning lines of the display to perform the display operation.

6. A drive control apparatus for controlling driving of a display device provided with drive means for sequentially selecting a plurality of scanning lines of a display to perform a raster scanning display operation, said drive control apparatus comprising:

storing means for storing image data to be displayed; and

updating means, including a program, for updating a portion of the image data stored in the storing means to different, updated image data, the updated image data being determined by said updating means using a command of the program,

wherein said updating means includes means for performing an updating operation without accessing the previously stored image data and for simultaneously supplying line information designating one of the scanning lines on which to display the updated data to said drive means.

7. A display apparatus comprising:

a display including a plurality of scanning lines;

storing means for storing image data to be displayed;

drive means for sequentially selecting a scanning line of said display and for driving said display to perform a raster scanning display operation, in accordance with the image data stored in said storing means; and

updating means, including a program, for performing an updating operation to update a portion of the image data stored in the storing means to different, updated image data, the updated image data being determined by said updating means using a command of the program;

wherein said updating means performs the updating operation without accessing the previously stored image data and simultaneously supplies line information designating one of the scanning lines on which to display the updated data to said drive means.