TELEVISION ON-SCREEN DISPLAY SYSTEM UTILIZING TEXT DATA COMPRESSION

AN ON-SCREEN DISPLAY SYSTEM FOR DISPLAYING INSTRUCTIONS FOR GUIDING A USER TO UTILIZE VARIOUS FEATURES OF A CONSUMER ELECTRONICS PRODUCT SUCH AS A TELEVISION RECEIVER OR VCR, INCLUDES A MEMORY (21) FOR STORING BOTH UNCOMPRESSED TEXT DATA AND COMPRESSED TEXT DATA, AND AN ASSOCIATED MICROPROCESSOR (19) FOR RETRIEVING THE TEXT DATA, DECOMPRESSING IT IF NECESSARY, AND PRESENTING IT TO A DISPLAY BUFFER (23). TEXT DATA COMPRESSION IS IN PART ACCOMPLISHED BY A DICTIONARY CONTAINING TEXT DATA REPRESENTING COMMONLY USED TEXT "STRINGS" COMPRISING ONE OR MORE WORDS WHICH IS STORED IN THE MEMORY (21). CODE WORDS RELATED TO THE LOCATION OF RESPECTIVE DICTIONARY ENTRIES IN MEMORY ARE SUBSTITUTED FOR RESPECTIVE UNCOMPRESSED TEXT DATA. TEXT DATA COMPRESSION IS ALSO ACCOMPLISHED BY SUBSTITUTING A FORMAT CHANGE CODE WORD INDICATING THAT ADJACENT TEXT REPRESENTING A FIRST STRING OF TEXT WITH A FIRST FORMAT, SUCH AS ALL LOWER CASE OR MIXED CASE, IS TO BE CONVERTED TO TEXT DATA REPRESENTING A SECOND STRING OF TEXT WITH A SECOND FORMAT, SUCH AS ALL UPPER CASE OR TITLE CASE. IN THIS WAY, TEXT DATA REPRESENTING TEXT DIFFERING ONLY IN FORMAT ONLY NEEDS TO BE STORED ONCE. THE FORMAT CHANGE CODE WORD IS EMPLOYED BOTH IN THE UNCOMPRESSED TEXT DATA PORTION OF THE MEMORY AND IN THE DICTIONARY PORTION OF THE MEMORY AND THE TEXT DATA, WHETHER UNCOMPRESSED OR COMPRESSED, IS RETRIEVED AND FORMATTED FOR DISPLAY IN THE SAME MANNER.FIGURE 1.