AUTOMATIC BRIGHTNESS LIMITER AUTOMATIC CONTROL CIRCUIT, CONTRAST LIMITER CONTROL CIRCUIT, LUMINANCE/ COLOR DIFFERENCE SIGNAL PROCESSOR AND VIDEO DISPLAY APPARATUS

摘要

THE OBJECT OF THE PRESENT INVENTION IS TO EASILY COMPENSATE AUTOMATIC BRIGHTNESS LIMITING PERFORMANCE AND AUTOMATIC CONTRAST LIMITING PERFORMANCE EVEN IF A PICTURE IS DISPLAYED WITH A DIFFERENT ASPECT RATIO AND TO PREVENT DETERIORATION OF PICTURE QUALITY SUCH AS GRADUATION AND SHARPNESS.A PICTURE DISPLAY APPARATUS INCLUDES ABL (AUTOMATIC BRIGHTNESS LIMITER) CIRCUIT (30) INCLUDING A COMPARISON CIRCUIT (6) FOR VARYING AN EHT COMPENSATION STARTING POINT, AN ABL GAIN CONTROL CIRCUIT (9) FOR VARYING A SLOPE OF EHT REGULATION CHARACTERISTIC AGAINST APL, AN ABL COMPARISON VOLTAGE GENERATOR (7), A DAC (8) FOR ADJUSTING AN ABL COMPENSATION STARTING POINT AND A DAC (10) FOR ADJUSTING AN ABL GAIN AND ACL (AUTOMATIC CONTRAST LIMITER) CIRCUIT (31) INCLUDING ANOTHER COMPARISON CIRCUIT (15) FOR VARYING AN EHT COMPENSATION STARTING POINT, AN ACL GAIN CONTROL CIRCUIT (18) FOR VARYING A SLOPE OF EHT REGULATION CHARACTERISTIC AGAINST APL, AN ACL COMPARISON VOLTAGE GENERATOR (16), A DAC (17) FOR ADJUSTING AN ACL COMPENSATION STARTING POINT AND A DAC (19) FOR ADJUSTING AN ACL GAIN.(FIG 3)