| 摘要 |
PROBLEM TO BE SOLVED: To provide an automatic focusing(AF) mechanism capable of eliminating the erroneous decision of the increase or decrease of an evaluation value and executing the accurate decision, suitable for a business or professional video camera and high in precision not by executing the decision of the increase or decrease of the evaluation value and the detection of the peak value thereof in a term that the evaluation value is a prescribed threshold value or below. SOLUTION: An AF block 137 is provided with an AF-IC 139 and a CPU for AF 138. The AF-IC 139 is provided with a luminance signal generation circuit and an evaluation value generation circuit. By the AF block 137, the high-frequency component of the specified area of a picture signal is extracted and the evaluation value is generated. According to the evaluation value, a command value given to the driving circuit 11c of the focusing lens 111 of the video camera is transmitted. Besides, the peak of the evaluation value is searched by comparing the present evaluation value with the evaluation value obtained before the prescribed term. In the term that the evaluation value is equal to or under the prescribed threshold value, the increase or the decrease thereof is not decided and the peak thereof is not detected. |
