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Patent Searching and Data


Title:
IMAGE PICKUP DEVICE
Document Type and Number:
Japanese Patent JPH06253206
Kind Code:
A
Abstract:

PURPOSE: To suppress the change in a random noise level by controlling exposure control and a video means and control of a signal processing means based on a correction coefficient through the comparison between a noise quantity and a reference noise quantity in a video signal.

CONSTITUTION: Prior to image pickup of an object, a microcomputer 13 obtains an exposure time TV0, an aperture AV0 and a gain G0 of an AGC circuit based on an output of an AE sensor 12. Then in the interrupting state, the exposure time is set to the TV0, and the aperture is set to the AV0 and then a black level is picked up and a black level video signal read from an image pickup element 2 is given via an sample-and-hold circuit 3 to the AGc circuit 4, in which the signal is multiplied by a multiple of G0, then a clamp circuit 5 clamps the signal to a level at a point (b) of a conversion range of an A/D converter 6 and the signal is converted into a digital signal. A noise level is measured by a noise level control circuit 102 in a DSP 7 from the black level signal and a comparator circuit 103 compares it with reference noise data in the memory 104 and an arithmetic circuit 105 calculates a correction coefficient. A system controller 14 controls the adder circuit or the like in a memory 8 by an exposure time, an AGC gain and a flash light quantity of a strobo 15 based on the correction coefficient.


Inventors:
Osozawa, Noriyoshi
Application Number:
JP1993000033613
Publication Date:
September 09, 1994
Filing Date:
February 23, 1993
Export Citation:
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Assignee:
CANON INC
International Classes:
H04N5/217; H04N5/238; (IPC1-7): H04N5/238; H04N5/217
Attorney, Agent or Firm:
大塚 康徳 (外1名)