Imaging system using solid-state CMOS imaging device
View Patent ↗Turning on and off of the light source illuminating an object to be imaged is judged based on brightness changes in small and large areas set up in the frame and an electric charge storage time for each pixel is set up to be equal to the turning-on-and-off period of the light source or an integral multiple thereof. The charge storage time is changed over responsive to the turning-on-and-off period of the light source or the integral multiple thereof to set up a stored light amount for each pixel stepwise and difference in the stored light amount between steps is interpolated by continuous gain control of read-out signals of pixels.
1. An imaging system including a solid-state CMOS imaging device and a signal processing semiconductor integrated circuit for processing read-out signals of pixels from said solid-state CMOS imaging device, comprising:
first level detection means for detecting brightness on a first area set up on an imaging area of said solid-state CMOS imaging device, said first area comprising a pixel area having a width smaller than a half interval width of a brightness difference shaped in strips on the imaging area caused by flicker;
second level detection means for detecting brightness on a second area larger than said first area, said second area comprising a pixel area in which said brightness difference caused by flicker is substantially smoothed;
judgment means for judging turning-on-and-off of a light source illuminating an object to be imaged on the basis of detection levels of said first and second level detection means; and
a control unit for setting up an intensity of a read-out signal for each pixel of said solid-state CMOS imaging device by means of processing in accordance with a program which controls both a transmission gain of said read-out signal of each pixel and a number of charge storage lines constituted by horizontal scanning lines as a unit,
wherein said judgment of the turning-on-and-off of said light source illuminating in accordance with the object on the basis of the detection levels of said first and second level detection means is performed by processing in accordance with the program in said control unit which judges whether a difference between maximum brightness values and minimum brightness values of the second area over a predetermined number of frames remain less than a predetermined value, and whether maximum brightness values and minimum brightness values of the first area over a predetermined number of frames satisfy a predetermined relation.
2. An imaging system including a solid-state CMOS imaging device and a signal processing semiconductor integrated circuit for processing read-out signals of pixels from said solid-state CMOS imaging device, comprising:
first level detection means which detects brightness on a first area set up on an imaging area of said solid-state CMOS imaging device, the first area which is a predetermined area in a frame, said first area comprising a pixel area having a width smaller than a half interval width of a brightness difference shaped in strips on the imaging area caused by flicker;
second level detection means which detects brightness on a second area which is set up on an imaging area of said solid-state CMOS imaging device, and is larger than said first area, the second area which is a predetermined area in the frame, said second area comprising a pixel area in which said brightness difference caused by flicker is substantially smoothed;
judgment means which judges turning-on-and-off of a light source illuminating in accordance with an object to be imaged on the basis of detection levels of said first and second level detection means; and
a control unit for setting up an intensity of a read-out signal for each pixel of said solid-state CMOS imaging device by means of processing in accordance with a program which controls both a transmission gain of said read-out signal of each pixel and a number of charge storage lines constituted by horizontal scanning lines as a unit,
wherein said judgment of the turning-on-and-off of said light source illuminating in accordance with the object on the basis of the detection levels of said first and second level detection means is performed by processing in accordance with the program in said control unit which judges whether a difference between maximum brightness values and minimum brightness values of the second area over a predetermined number of frames remain less than a predetermined value, and whether maximum brightness values and minimum brightness values of the first area over a predetermined number of frames satisfy a predetermined relation.