| 摘要 |
A focus detecting device is disclosed for use in a photographic camera. The device includes two rows of photoelectric focus detecting elements juxtaposed on a substrate in a symmetrical relationship with respect to the center line between both rows of focus detecting elements and arranged to receive light reflected from an object to be photographed through an optical focussing lens system. One row of the focus detecting elements are connected to a dc power source through individual electrical switching elements having their gates coupled to the corresponding outputs of a first trigger pulse generator for generating a train of sequential trigger pulses and through a first common load resistor. Likewise, the other row of the focus detecting elements are connected to the dc power source through individual electrical switching elements having their gates coupled to the corresponding outputs of a second trigger pulse generator for generating a train of sequential trigger pulses synchronized with, or delayed or advanced by a predetermined time interval to, the trigger pulse train from the first generator and through a second common load resistor. The common connection of the first resistor to the one row of the detecting elements and the common connection of the second resistor to the other row of the detecting elements are connected to the corresponding inputs of a comparator. Thus, the focus condition of the object on both the rows of focus detecting elements is detected in accordance with an output from the comparator based on the upper-lower image coincidence method and/or the contrast method.
|
