Image sensing device
In order to stably detect a flicker under an illumination of a fluorescent lamp with an XY-addressed-scanning type image sensor used and to cancel the flicker, the present invention provides an image sensing device, wherein a video signal in any area on an imaging plane is first integrated per frame period, then an integrated value in a current frame is sequentially compared with a one-frame previously integrated value, next whether a variation pattern of the integrated value matches one of flicker patterns when the flicker occurs is determined, then an existence of the flicker is determined when an identical flicker pattern is seen more than two consecutive times.
1. An image sensing device which images a picture using an image sensor, comprising:
an integrator for obtaining a video signal during imaging, integrating the video signal for each of frame periods on any domain in an imaging plane, and calculating integrated values at a plurality of isolated domains spaced apart from each other on the imaging plane, respectively;
a pattern determination section for obtaining a first signal integrated value for a current frame from the integrator, comparing the first signal integrated value with a second signal integrated value for a previous frame, that occurred one frame before the current frame, determining whether the first signal integrated value increases, decreases, or remains unchanged from the second signal integrated value, and determining in each domain whether a variation pattern including increase, decrease, and no change on a signal integration value for a predetermined number of the previous frames matches one of flicker patterns which are variation patterns including increase, decrease, and no change on the signal integrated value on the predetermined number of the previous frames, when a fluorescent lamp flicker occurs; and
a repetition determination section for determining that the flicker occurs in each domain, if the pattern determination section determines that the variation pattern matches one of the flicker patterns, and the variation pattern of the integrated value matches an identical flicker pattern at least over two flicker periods,
wherein the plurality of the domains integrated by the integrator are set at vertically isolated locations spaced apart from each other on the imaging plane, so that the exposure start timing of the image sensor in each domain against the brightness variation of the fluorescent lamp can be different from that at least in one domain.
2. The image sensing device of claim 1 , wherein:
the pattern determination section determines the variation pattern and the repetition determination section determines the existence of the flicker, on the basis of the integrated value in each of the domains, respectively, and
when the number of the domains of the existence of the flicker determined by the repetition determination section is more than a half of the total number of the domain, the existence of the flicker is determined.
3. The image sensing device of claim 1 , wherein the image sensor is an XY-addressed-scanning type image sensor.
4. The image sensing device of claim 1 , further comprising a shutter speed controller which cancels the flicker by setting a signal storage time of the image sensor as the brightness period of the fluorescent lamp multiplied by an integer, when the flicker is detected.