| 摘要 |
PURPOSE:To read an original which includes no red-color character/image at about seven-times speed as using a first light source by constituting an image reader so that its first light source emits an orange color or red color light while a second light source emits a green color or yellowish green or yellow color light. CONSTITUTION:For the first light source, a red-color LED array 3 whose peak wavelength is 660nm is used, and a yellowish-green LED array 4 whose peak wavelength is 565nm is used for the second light source. The LED 3 has an average photocurrent apoximately six times of that of the LED 4, and is seven times as rapid as the LED 4 in initial response speed. Accordingly, by using the LED 3, a highly-sensitive and high-speed image reading can be attained. In case no red color character/image is included on an original, a switching switch 12 swites to the LED 3 to read at high speed, but in case red color character/image is included, the LED 4 is employed. When the LED 3 is used, a first amplification part 14 is not used.
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