发明授权
US4853788A Automatic focusing circuit selectively using multiple focus evaluating
curves having differing characteristics
失效
选择性地使用具有不同特征的多个焦点评估曲线的自动聚焦电路
- 专利标题: Automatic focusing circuit selectively using multiple focus evaluating curves having differing characteristics
- 专利标题(中): 选择性地使用具有不同特征的多个焦点评估曲线的自动聚焦电路
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申请号: US155900申请日: 1988-02-16
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公开(公告)号: US4853788A公开(公告)日: 1989-08-01
- 发明人: Hirotsugu Murashima , Satoru Maeda
- 申请人: Hirotsugu Murashima , Satoru Maeda
- 申请人地址: JPX Osaka
- 专利权人: Sanyo Electric Co., Ltd.
- 当前专利权人: Sanyo Electric Co., Ltd.
- 当前专利权人地址: JPX Osaka
- 优先权: JPX62-34764 19870218; JPX62-34766 19870218; JPX62-49512 19870304
- 主分类号: H04N5/232
- IPC分类号: H04N5/232
摘要:
In an automatic focusing circuit of a video camera, an automatic focusing operation is performed in response to a first focus evaluating value which is steeply changed and a second focus evaluating value which is gently changed, in response to the position of a lens, in which the first and second focus evaluation values are generated in response to a video signal obtained in an image sensing circuit 4. When a comparator 28 determines that the first focus evaluating value does not reach a predetermined reference value, a in-focus state detecting circuit 24 and a focusing motor control circuit 10 perform an intermittent automatic focusing operating every other field in response to the second focus evaluating value. When the comparator 28 determines that the first focus evaluating value exceeds the perdetermined reference value, the in-focus state detecting circuit 24 and the focusing motor control circuit 10 perform an automatic focusing operation more frequently every field in response to the first focus evaluating value. The moment a change of an object is detected after the object is in focus, the automatic focusing operation is resumed in response to the second focus evaluating value.
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