Automatic focus matching device

Abstract

Abstract PURPOSE:To improve the accuracy of focusing for an image that includes an object of high brightness by cutting off a video signal or a high frequency component signal in case the level of the video signal exceeds a detection level not to input the signal to the controller of a focus matching device for lens. CONSTITUTION:If a comparator 33 detects a high brightness part in a video signal, a gate circuit 34 cuts off a high frequency component signal not to input the signal to a reference frequency component detection circuit 29. A detection level generator 35 outputs a detection level A during a time when the comparator detects a high brightness part, but outputs a detection level 8 that is slightly lower than the detection level A. Accordingly, a detection level 42 has a hysterisis characteristic as shown in the figure. With such a constitution, the high frequency component signal can be cut off against the high brightness part detected by the comparator 33. Additionally, even in case a video signal 44 includes a noise component and exceeds the detection level A many times as shown in the figure, the output of a comparator 45 is hardly influenced by the noise thanks to the hysterisis characteristic.

Inventors

• 👤 Ichiro Kojima
• 👤 一朗 小島
• 👤 Hideo Toyoda
• 👤 豊田　秀夫
• 👤 Yoshinori Kitamura
• 👤 北村　好徳

Bibliographic Details