Title:
AUTOMATIC BLACK LEVEL CONTROL CIRCUIT
Document Type and Number:
Japanese Patent JP3531545
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To provide an automatic black control circuit which can suppress the rise of a black level when an object is image-picked up in a dark situation.
SOLUTION: Image pickup elements 1, 1a and 1b are the photoelectric conversion elements of CCD and the like. Preamplifiers 2, 2a, and 2b output amplified signals 22, 22a and 22b. Gain controllers 3, 3a and 3b control gains. A/D converters 4, 4a and 4b execute A/D conversion. Digital process circuits 5, 5a and 5b output digitally processed outputs 25, 25a and 25b. An encoder 7 outputs encoder output 26 and a luminance signal 28. A D/A converter 8 D/A- converts encoder output 26. A two-dimensional filter 11 outputs filter output 31 from the luminance signal 28 and delay signals 29 and 30. A black level detection circuit 12 outputs black level output 32. CPU 13 outputs a level control signal 33 to the digital process circuit 5, 5a and 5b.
Inventors:
Ishii, Kenji
Application Number:
JP24035499A
Publication Date:
May 31, 2004
Filing Date:
August 26, 1999
Export Citation:
Assignee:
NEC CORP
International Classes:
H04N5/14; H04N5/16; H04N5/243; (IPC1-7): H04N5/16; H04N5/243
Attorney, Agent or Firm:
机 昌彦 （外２名）
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