Patent ID: 6831695
Filing Date: 2004-12-14
Classification: H04N

Abstract:
An image pickup apparatus for photoelectrically converting an optical image focused on photosensitive cells of an image sensor via a lens to thereby output image signals corresponding to said optical image, said apparatus comprising:a shutter for intercepting, when an exposure time expires with the photosensitive cells generating signal charges, light incident to the image sensor; a memory for storing the image signals output from the image sensor; a controller for controlling an operation of said image pickup apparatus and determining an amount of exposure for picking up a scene in a form of a still picture; and a combining circuit for combining the image signals read out of said memory; said controller comprising: an exposure value determining circuit for determining a first exposure value based on the incident light and a second exposure value that effects lower exposure than said first exposure value; an exposure control circuit for causing the optical image to be photoelectrically converted over the exposure time that consists of a first and a second period of time respectively corresponding to the first exposure value and the second exposure value; a first read control circuit for causing, at a timing corresponding to the first period of time, signal charges generated by and stored in the photosensitive cells to be shifted to transfer paths of the image sensor, thereby causing said image sensor to output a first signal corresponding to said signal charges; a light intercepting circuit for causing, at an end of the exposure time, said shutter to intercept the incident light to thereby end the second period of time following the first period of time; a second read control circuit for causing, after said image sensor has output the first signal, said image sensor to output a second signal corresponding to signal charges generated by and stored in the photosensitive cells during the second period of time; a ratio calculating circuit for calculating an exposure amount ratio between the first signal and the second signal; and a correcting circuit for correcting a level of the second signal in accordance with the exposure amount ratio; said combining circuit combining image signals, which respectively correspond to the first signal and the second signal corrected by said correcting circuit, for thereby outputting an image signal representative of a single frame picked up during the exposure time.