AUTOMATIC FOCUSING DEVICE

摘要

PURPOSE:To prevent an erroneous focusing operation and to improve the follow-up characteristic to a moving subject by integrating the video signals corresponding to screens divided to >=2 screens by every region and detecting the subject change from the region differential signal formed form the difference at every prescribed period. CONSTITUTION:The video signals are added by every one field in integrators 10 to 18 and are inputted to difference detecting circuits 19 to 27. The difference detecting circuits 19 to 27 detect the difference between the fields of the output signals of the integrating circuit. The difference in the average brightness of each of the respective regions detected by a region difference circuit 100 is inputted to a subject change detecting circuit 8 which supplies the signal corresponding to the subject change to a control circuit 7. The control circuit 7 controls the focusing operation according to the subject change signal outputted from a subject change detecting circuit 8. The excellent automatic focusing device which has decreased malfunctions is obtd. in this way.