Automatic brightness correction apparatus for image display device

An automatic brightness correction apparatus for automatically correcting the brightness property of an image display device, comprising:

• a video signal receiving circuit;
• a test pulse generator for generating a test pulse at a predetermined level;
• an inserter for inserting the test pulse generated by the test pulse generator into the video signal provided from the video signal receiving circuit;
• a level corrector for correcting the level of a composite video signal provided from the inserter by using a correction signal pertinent to the level of the test pulse in the composite video signal;
• an image display device for displaying the composite video signal corrected by the level corrector;
• a brightness information detector for detecting brightness information of the composite video signal displayed on the image display device;
• a benchmark memory for storing benchmarks pertinent to a plurality of levels of the test pulse;
• a benchmark selector for selecting a benchmark pertinent to the brightness information signal from the benchmark memory;
• a comparator for comparing the brightness information signal detected by the brightness information detector and the benchmark selected by the benchmark selector, and
• a controller for controlling the level corrector to revise the correction data pertinent to the signal level of the test pulse in the level corrector based on the comparison result provided from the comparator.

An automatic brightness corrections apparatus, comprising:

• a first A/D converter for converting an input analog video signal into a digital video signal;
• a test pulse generator for generating digital test pulse at a predetermined level within a level range including an intermediate level;
• a test pulse inserter for inserting the digital test pulse supplied from the test pulse generator so that the test pulse is inserted to the video signal in the specific position of the digital video signal supplied from the first A/D converter, and for outputting the signal;
• a level corrector for correcting the level of the digital video signal supplied from the test pulse inserter by the correcting value which corresponds to the level of the signal;
• a D/A converter for converting the digital video signal supplied from the level corrector into the analog video signal;
• a brightness information detector for detecting the brightness of an video image display device which is driven by the test pulse supplied from the D/A converter, and outputting a brightness information signal of the detection result;
• a second A/D converter for converting the brightness information signal supplied from the brightness information detector into the digital brightness information signal;
• a benchmark memory for storing a number of benchmarks;
• a benchmark selector for selectively reading out a benchmark pertinent to the test pulse from the benchmark memory;
• a comparator for comparing the digital brightness information signal from the second A/D converter and the benchmark selected by the benchmark selector;
• and
• a controller for controlling the level corrector to revise the correction data pertinent to the signal level of the test pulse in the level corrector based on the comparison result provided from the comparator.

An automatic brightness correction apparatus for correcting brightness properties of a plurality of parallelly connected image display device, comprising:

• a plurality of brightness information detectors for detecting each brightness information signals of the test image signals with predetermined levels displayed on the image display devices;
• and
• a switch for outputting brightness information signals detected by the plurality of brightness information detectors by successively switching the brightness information signals;
• wherein it is characterized by that the apparatus determines differences of the brightness information signals of the image display devices output from the switch from benchmarks assigned previously for the brightness information signal, and then correct in a timeshared fashion the levels of the test video signals displayed on the corresponding image display devices based on the differences.