Digital camera and control method thereof

Abstract

A solid-state image sensor includes a photocell array for accumulating signal charge for each pixel in accordance with progress of exposure, and a read circuit for reading out information on the accumulated signal charge from the photocell array. With an insulating structure between its input and output, an amplifier in the read circuit generates an output signal without resetting the accumulated charge in the photocell. Information on the accumulated charge is read out at different exposure times while signal charge is accumulated during exposure, and a plurality of image signals can sequentially be obtained without destroying the information.

What is claimed is:  
     
         1 . A digital camera comprising: 
 an image sensor including a photocell array for accumulating charge for each pixel in accordance with progress of exposure, and a read circuit for reading-out information on accumulated charge nondestructively from said photocell array; and    a read controller for repeatedly activating said read circuit while said photocell array accumulates charge during exposure, to thereby sequentially capture a plurality of image signals corresponding to a plurality of exposure times with respect to a substantially same scene.    
     
     
         2 . The digital camera according to  claim 1 , further comprising: 
 a memory capable of storing at least two image signals among said plurality of image signals corresponding to said plurality of exposure times.    
     
     
         3 . The digital camera according to  claim 2 , further comprising: 
 judging means for making a judgement whether said memory has enough free space for a new image signal to be stored; and    a memory controller for erasing the oldest one of already-stored image signals from said memory if said memory has not enough space, and storing said new image signal.    
     
     
         4 . The digital camera according to  claim 1 , further comprising: 
 a display device capable of displaying an image; and    a display controller for receiving said plurality of image signals from said read controller and controlling said display device to display a plurality of images corresponding to said plurality of image signals.    
     
     
         5 . The digital camera according to  claim 4 , wherein 
 said display controller controls said display device to selectively display said plurality of images in time-sequence in accordance with an order of respective exposure times.    
     
     
         6 . The digital camera according to  claim 4 , wherein 
 said display controller controls said display device to simultaneously display two or more of said plurality of images.    
     
     
         7 . The digital camera according to  claim 4 , further comprising: 
 a manual operating member for selecting one of said plurality of images displayed, to determine a selected-image; and    a recording controller for storing said selected-image in a recording medium.    
     
     
         8 . The digital camera according to  claim 1 , further comprising: 
 setting means for setting said plurality of exposure times in said read controller.    
     
     
         9 . The digital camera according to  claim 8 , wherein 
 said plurality of exposure times are determined such that a first time period elapsed before capturing a first image signal from start of exposure is longer than a second time period elapsed before capturing a second image signal since said first image signal is captured.    
     
     
         10 . The digital camera according to  claim 1 , further comprising: 
 a switching operating member for switching between a multiple exposure mode and a single exposure mode, wherein    in said multiple exposure mode, said read controller sequentially captures said plurality of image signals corresponding to said plurality of exposure times with respect to a substantially same scene, and    in said single exposure mode, said read controller captures a single image signal corresponding to one exposure time with respect to a same scene.    
     
     
         11 . A method of controlling a digital camera comprising an image sensor capable of reading-out information on accumulated charge nondestructively from a photocell array, comprising the steps of: 
 (a) selectively setting a multiple exposure mode and a single exposure mode;    (b) entering a command to start imaging; and    (c) electively executing the steps of: 
 (c-1) in said multiple exposure mode, sequentially capturing a plurality of image signals corresponding to a plurality of exposure times with respect to a substantially same scene, and  
 (c-2) in said single exposure mode, capturing a single image signal corresponding to one exposure time with respect to a same scene.  
   
     
     
         12 . The method according to  claim 11  further comprising the step of: 
 (d) displaying at least one image captured.