Solid-state image sensor having control cells for developing signals for image-shooting control under poor illumination

Abstract

A solid-state image sensor and a digital cameral capable of executing accurate image-shooting adjustment even in a low illumination environment. A charge coupled device type of image sensor includes red, green and blue pixel cells provided with color filter segments and control cells not provided with color filter segments. When a controller determines that the illumination of a scene to be picked up is short, a digital signal processor generates estimated luminance and contrast values for automatic exposure and automatic focus controls in accordance with the outputs of the control cells. An exposure value and the focal position of a lens are adjusted in accordance with those estimated values. The scene is shot in the form of a still picture in response to a shutter release signal.

1 - 19 . (canceled)  
     
     
         20 . A digital camera for receiving an optical image via a lens and generating image signals representative of the optical image, comprising: 
 an image sensor including a plurality of first cells, which are not provided with color filter segments at a light incidence side, and a plurality of second cells, which are provided with the color filter segments, said first cells and said second cells respectively outputting first signals and second signals each corresponding to a particular quantity of incident light;    a signal processing circuit for processing signals read out from said image sensor for thereby generating pixel values pixel by pixel and generating pixel signals representative of the optical image, based on the pixel values; and    a controller for executing control for reading out the first signals and the second signals from said image sensor;    said signal processing circuit generating an estimated luminance value for executing exposure control when executing image-shooting adjustment before a shot;    said controller driving, on a start of a shot, said image sensor with an exposure value matching with the estimated luminance value while said signal processing circuit corrects pixel values read out from said first cells with the second signals.    
     
     
         21 . The digital camera in accordance with  claim 20 , wherein said signal processing circuit generates an estimated contrast value for controlling a focal position of the lens in accordance with the first signals when executing image-shooting adjustment before a shot, and 
 said controller controls the focal position of the lens in accordance with the estimated contrast value.    
     
     
         22 . The digital camera in accordance with  claim 20 , wherein said first cells are so positioned as to be usable for both of an AE (automatic Exposure) control and an AF (Automatic Focus) control.