Image sensing apparatus and control method thereof

Abstract

An image sensing apparatus, having an image sensor for sensing an image of an object and an analog-digital converter which operates at a predetermined frequency and converts an analog signal read from the image sensor to a digital signal, controls the relationship between a phase of the analog signal read from the image sensor and a phase of a timing signal for operating the analog-digital converter in accordance with the peripheral condition.

What is claimed is: 
     
       1. An image sensing apparatus having an image sensor, which has a first area for sensing an image of an object and a second area which is shielded from light, for sensing an image of an object, comprising:
 an analog-digital converter that operates at a predetermined frequency and converts an analog signal read from the image sensor to a digital signal; and   a controller that controls a relationship between a phase of a timing signal for reading out the analog signal from the image sensor and a phase of a timing signal for operating said analog-digital converter on the basis of signals obtained from the second area by relatively shifting the phase of the timing signal for reading out the analog signal and the phase of the timing signal for operating said analog-digital converter, and converting the analog signal by said analog-digital converter for each shifted phase.   
     
     
       2. The image sensing apparatus according to  claim 1  further comprising:
 a plurality of output units that read signals from the image sensor; and 
 a multiplexer that multiplexes the signals from said plurality of output units to a time sequential signal and outputs the time sequential signal, 
 wherein the time sequential signal from said multiplexer is outputted to said analog-digital converter. 
 
     
     
       3. The image sensing apparatus according to  claim 1 , wherein said controller adjusts the relationship between the phase of the timing signal for reading out the analog signal from the image sensor and the phase of the timing signal for operating said analog-digital converter so that a digital signal obtained by converting the signal read from the image sensor by said analog-digital converter becomes maximum. 
     
     
       4. The image sensing apparatus according to  claim 2 , wherein said controller adjusts the relationship between the phase of the timing signal for reading out the analog signal from the image sensor and the phase of the timing signal for operating said analog-digital converter so that a difference between the signals from said plurality of output units becomes minimum. 
     
     
       5. A control method of an image sensing apparatus having an image sensor, which has a first area for sensing an image of an object and a second area which is shielded from light, for sensing an image of an object, and an analog-digital converter which operates at a predetermined frequency and converts an analog signal read from the image sensor to a digital signal, comprising:
 determining a relationship between a phase of a timing signal for reading out the analog signal from the image sensor and a phase of a timing signal for operating said analog-digital converter on the basis of signals obtained from the second area by relatively shifting the phase of the timing signal for reading out the analog signal and the phase of the timing signal for operating said analog-digital converter, and converting the analog signal by said analog-digital converter for each shifted phase.   
     
     
       6. An image sensing apparatus having an image sensor for sensing an image of an object, comprising:
 a temperature sensor that measures temperature;   an analog-digital converter that operates at a predetermined frequency to convert a first analog signal to a first digital signal and convert a second analog signal to a second digital signal, wherein the first analog signal and the second analog signal are read from different pixels in a line via different channels; and   a controller that controls a relationship between a first phase of a timing signal for reading out the first analog signal and the second analog signal from the image sensor and a second phase of a timing signal for operating said analog-digital converter in accordance with the temperature measured by the temperature sensor.   
     
     
       7. The image sensing apparatus according to claim 6, further comprising a memory that stores a plurality of different phases for the first and second phases of the timing signal in correspondence with different temperatures in advance,
 wherein said controller searches the first and second phases of the timing signal which corresponds to the measured temperature.   
     
     
       8. The image sensing apparatus according to claim 6, further comprising:
 a plurality of output units, corresponding to the different channels, that read the first and second analog signals from the image sensor; and   a multiplexer that multiplexes the first and second analog signals from said plurality of output units into a time sequential signal and outputs the time sequential signal,   wherein the time sequential signal from said multiplexer is outputted to said analog-digital converter.   
     
     
       9. The image sensing apparatus according to claim 6, wherein said controller adjusts the relationship between the first phase of the timing signal for reading out the first and second analog signals from the image sensor and the second phase of the timing signal for operating said analog-digital converter so that the digital signals obtained by converting the first and second analog signals by said analog-digital converter becomes maximum. 
     
     
       10. The image sensing apparatus according to claim 6, wherein said controller adjusts the relationship between the first phase of the timing signal for reading out the first and second analog signal from said image sensor and the second phase of the timing signal for operating said analog-digital converter so that a difference between the digital signals obtained by converting the first and second analog signals becomes minimum.