| 摘要 |
PROBLEM TO BE SOLVED: To provide a light intensity control device for an electronic endoscope constantly keeping a screen at an appropriate brightness, when the screen becomes a halation state, quickly returning the screen to the appropriate bright, and improving an observation performance. SOLUTION: In this light intensity control device for the electronic endoscope, an iris control circuit 9 adjusts the light intensity of an iris 2. In a halation determination circuit 22, a brightness signal (signal U) from a mask processing circuit 40 is input in an integral circuit 19 and nonlinear correction circuit 21 respectively and then, respective levels of an integral result (signal E) integrated by the integral circuit 19 and a correction result (signal D) nonlinearly corrected by the nonlinear correction circuit 21 are compared to each other by a comparator circuit 20. Even if the brightness in the circumferential screen are different relative to a same observation object, the nonlinear correction circuit 21, for detecting the fixed halation range, sets a table value to, when the brightness of respective parts on the screen is low, output an approximately fixed low-level voltage and, when being high, output an approximately fixed high-level voltage using a primary table provided in its inside and performs the nonlinear processing relative to the input signal U based on the setting. COPYRIGHT: (C)2005,JPO&NCIPI
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