Image sensor for detecting flicker noise and method thereof

A method for detecting a flicker noise of an image sensor, comprising the steps of:

• (a) securing information about an image of each of a first and a second pixel row by differing exposure points of the first and the second pixel rows having a first exposure time and repeating the image information securing process as changing the exposure points of the first and the second pixel rows;
• (b) capturing information about an image of each of a third and a fourth pixel row by differing exposure points of the third and the fourth pixel rows having a second exposure time and repeating the image information capturing process as changing the exposure points of the third and the fourth pixel rows;
• (c) calculating an average value of the image information for each of the first to the fourth pixel rows in every image information detecting process;
• (d) ciphering a maximum value and a minimum value among average values for said each of the first to the fourth pixel rows obtained from the step (c);
• (e) determining a first subtract value by subtracting the minimum value from the maximum value of the first pixel row, deciding a second subtract value by subtracting the minimum value from the maximum value of the second pixel row, and outputting a smaller one of the first subtract value and the second subtract value as a first minimum subtract value;
• (f) determining a third subtract value by subtracting the minimum value from the maximum value of the third pixel row, deciding a fourth subtract value by subtracting the minimum value from the maximum value of the fourth pixel row, and outputting a smaller one of the third subtract value and the fourth subtract value as a second minimum subtract value;
• and
• (g) deciding an exposure time corresponding to the flicker noise by comparing the first minimum subtract value and the second minimum subtract value.

An image sensor comprising:

• a pixel array for capturing information about an image provided from the outside and having N pixel rows and M pixel columns for maximizing a feature of reacting to light, wherein M and N are integers, respectively;
• a flicker noise detective pixel unit containing X pixel rows, which has a form extended from the N pixel rows of the pixel array, and M pixel columns, wherein each pair of X pixel rows has an identical exposure time and X is an even number;
• and
• a flicker noise for controlling an exposure point for the flicker noise detective pixel unit and detecting the flicker noise by using outputs of the flicker noise detective pixel unit.