| 摘要 |
<p>A device for sensing a position being in focus comprises a CCD image sensor having a light reception part on a plurality of pixels of which a subject image formed by an optical system for image formation, that is an object an in-focus position of which is to be sensed, is projected, a shift register which transfers the charge read out from each pixel in synchronism with a charge transferring clock, and an output part in which the charges transferred by the shift register are accumulated one after another; a pixel reading out circuit for reading out each charge stored in each pixel to the shift register by applying a pixel reading out signal to the CCD image sensor, a sampling circuit for sampling the charge stored in the output part to obtain the luminance signal corresponding to each pixel, a focus computing part for computing an in-focus position of the optical system for image formation according to the luminance signal sampled by the sampling circuit, a reset circuit for resetting the charge in the output part every period, which is obtained through multiplying the half period of the charge transferring clock by an integer according to the charge storing state of the pixel.</p> |
