| 摘要 |
PURPOSE:To improve an S/N to detect accurately a focus up to a long distance by integrating directly a photocurrent generated in a photoelectric transducer and supplying a bias current in the direction opposite to the integrating direction of the other capacitor when the photocurrent quantity integrated by one capacitor is cancelled. CONSTITUTION:Photocurrent quantities A0 and B0 are integrated by capacitors DA and DB, and reverse bias currents IDA and IDB are generated and are supplied. Simultaneously, photocurrent quantities A0 and B0 are integrated with opposite polarities by capacitors CA and CB. The reflected light from an object due to light projection and the peripheral light are made incident on photoelectric transducers SA and SB, and corresponding photocurrent quantities (A+A0) and (B+B0) are integrated by capacitors CA and CB. Differences between integrated photocurrent quantities A0 and B0 and integrated photocurrent quantities (A+A0) and (B+B0), namely, photocurrent quantities A and B corresponding to proportions of the light incident on photoelectric transducers SA and SB to the reflected light due to light projection are held in capacitors CA and CB respectively. |
