Patent ID: 6094204
Filing Date: 2000-07-25
Classification: G09G

Abstract:
A graphics display unit having a frame buffer, an image drawing unit, a display unit and a D/A converter, said graphics unit comprising:said frame buffer including a normal data storage region for directly storing a display content as normal data, and a compression data storage region for storing said normal data after being compressed as compression data; andsaid display unit including:a flag buffer for storing flag information indicating as to whether the storage content (compression data) of said compression data storage region is valid, or invalid;a compressing unit for compressing the storage content (normal data) of said normal data storage region to write the compressed normal data into said compression data storage region;expanding unit for reading the storage content of said compression data storage region to restore an original image condition from said read storage content; anda control unit for controlling said flag buffer, said compressing unit, and said expanding unit in such a manner that when a writing operation is performed from the image drawing unit to the said normal data storage region, the flag information of the flag buffer is invalidated; when display data is read out from said frame buffer, the control unit refers to said flag information of said flag buffer; when the read flag information is valid, the compression data is read out from said compression data storage region and the original image data restored by said expanding unit is outputted to said D/A converter; when the flag information is invalid, the normal data read from said normal data storage region is directly outputted to the D/A converter and also the data compressed by said compressing unit is written into said compression data storage region; and when said compression data writing operation is ended, the flag information of said flag buffer is set to be valid.