Image pickup device

Abstract

Abstract PURPOSE:To precisely and rapidly execute focusing by making the center of an aperture-stop eccentric to an optical axis and adjusting an image pickup lens for focusing in a focusing position with a video signal detected by an image pickup element in at least two eccentric positions of the aperture-stop. CONSTITUTION:When the positions of an image pickup surface and an image forming surface are deviated, a light beam emitted from one point of an object forms the images into the different positions on the image pickup surface according to a position that it passes through the image pickup lens 2. Then, when the center position is displaced by rotating the aperture-stop 10, the video signal obtained from the image pickup element 3 changes. The moving direction of an image plane with the video signal becomes the same moving direction of the aperture-stop 10 when the image forming surface is farther from the pickup lens 2 than the image pickup surface and it becomes an opposite direction when the image forming surface is closer to the lens 2 than the image pickup surface. When the moving quantity of the aperture-stop 10 is fixed, the moving quantity of the image plane based on the video signal is nearly proportioned to the moving quantity of defocusing. Then, a focus can be detected by using the video signal from the image pickup element 3 and moreover the direction and the quantity of defocusing can be known.

Inventors

• 👤 Takahiro Nakamura

Bibliographic Details