| 摘要 |
PURPOSE:To improve focusing accuracy by reducing the influence of stepwise voltage variation caused between the effective part and ineffective part of the high frequency component of the output of a line sensor. CONSTITUTION:Projection image information incident on an image sensor is read as a time-series output signal within a read time, a high frequency component obtained by filtering said output signal is rectified on a half-wave basis and begins to be integrated behind an effective output signal for an effective picture element of an image sensor, and this integral value is used to decide focusing. Namely, the high frequency component C of the time-series output signal B of the image sensor contains false signals C1 and C2, but this high frequency component C is rectified on a half-wave basis to erase the false signal C2. Further the integration is started t1 after the false signal C1, so the false signal C1 is put outside an integration range and this integral value E, therefore, contains either the false signal C1 or C2. Consequently, focusing control accuracy is improved. |
