| 摘要 |
PROBLEM TO BE SOLVED: To shorten the light-quantity start-up time of a device which reads an image by lighting a document with a light source such as a fluorescent lamp by making it possible to estimate the temperature at the periphery of the light source with inexpensive and simple constitution. SOLUTION: The light source 101 lights the document and the reflected light from the document is imaged on the photodetection surface of a CCD 103 by a lens 102 to read a document image. Further, a light source control part 108 varies the quantity of light of the light source 101 and time base variation in the quantity of light is detected from the reflected light from a white standard plate 112 to estimate the temperature at the periphery of the light source from the detected value. According to the estimated temperature, the quantity of light of the light source 101 in standby mode is controlled.
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