Uses the ambient light detection device and the same ambient light detection device the laser illumination control unit null for the bar-code reader

摘要

PURPOSE: To eliminate an explanation of an operation while accurately obtaining a signal of the effect that there are changes of a detected peripheral light in predetermined value and predetermined time or more and to reduce its cost by detecting a light of a periphery where an apparatus is disposed and outputting the signal when the detected peripheral light is changed in the predetermined value and predetermined time or more. ;CONSTITUTION: Photodetecting means 3 of peripheral light detecting means 1 detects a light of a periphery where an apparatus is disposed, and converts it to an electric signal in which directivity 10 is imparted to its photodetecting sensitivity. This signal is amplified by an amplifier 4 while controlling its amplification factor based on optical information of the periphery by a controller 9. The amplified signal is integrated by integrating means 5 of deciding means 2 in terms of a predetermined time constant, and lower limiter means 8 invalidates a light change detection in which a peripheral light level is a predetermined value or less. Comparison reference information is generated from the integrated signal by a generator 6, and compared with an output of the means 5 by a comparator 7. Thus, when the detected peripheral light is varied in a predetermined time or more, forcible output means 11 forcibly outputs a signal equivalent to the signal of the effect.;COPYRIGHT: (C)1995,JPO