| 摘要 |
<p>A focus detecting system includes first and second lens devices for forming first and second auxiliary images of an object on first and second detector devices, respectively. Each detector device includes a corresponding plurality of linearly displaced light responsive elements. Before initiating a focus detecting function, a light diffusing device is positioned in the light paths ahead of the detector devices to effect substantially equal illumination of the detector devices. A balancing circuit connected to the detector devices or the a balancing charge representative of any inequality in the signals fuel to the corresponding light responsive elements. When the focus detecting action is initiated, the light diffusing device is removed and one of the lens devices moves with respect to its associated detector device to shift the light distribution pattern of the corresponding auxiliary image. The moving lens device is so coupled to a moving objective lens, which focusses a principal image of the object on a light sensitive film, that when the principal image is in focus, equal amounts of light will fall on corresponding light responsive elements of the first and second detector devices. The stored balancing charge is combined with the signals provided by the photo responsive elements during a focus detecting operation to provide compensated signals which are then processed to effect the termination of the movement of the objective lens when the principal image is properly focussed.</p> |
