| 摘要 |
PURPOSE:To detect an error signal in the output of image pickup element and to attain accurate phase detection as to a low illuminance object by providing a spatial reference optical image to an object, and adding a reference signal generating section and a phase detection section. CONSTITUTION:A white scattering layer 53 together with a light shield layer 52 are provided as a strip to the uppermost face of the side of the image pickup element of the object and a projection light 55 is reflected on the condition that the light is reflected totally at the transmission section. Then the image pickup element output is clipped at the lower side even at a low illuminance including the dark state to obtain a phase detection reference signal with a sufficient quantity. Moreover, the signal is shaped by a reference signal generating section 81 having the upper clip provided to the reference signal section 8, and amplified to a required level by a reference signal adjustment section 82. Moreover, a weak signal such as a stain is subject to amplitude and phase adjustment to maximize the phase detection output by the phase adjustment section 91 provided to a phase detection section 9 after AC amplification and the result is fed to the phase detection section 92. Thus, accurate phase detection is attained as to a low illuminance object and a fault signal in the output of image pickup element is detected. |
