| 摘要 |
PROBLEM TO BE SOLVED: To provide a picture input device with ease of maintenance and high reliability by using an inner thermal ray absorbing glass plate to absorb most thermal radiation energy in a lighting device provided to the picture input device for postal matters and using a window glass plate itself at an outermost part that transmits through the thermal radiation energy to hardly cause baking even when a contamination is deposited onto the glass plate for a long time. SOLUTION: This picture input device is configured such that a plurality of lighting light emission window glass plates are employed for a lighting unit, thermal ray absorbing glass plates are adopted for the inner window glass plates 28 other than the outermost window glass 46 to absorb the thermal radiation energy from the light source, an air supply unit 7 is used to decrease the temperature of the thermal ray absorption glass plates that are the internal window glass plates 28 through forced cooling thereby minimizing secondary radiation of the thermal radiation energy from the glass plates themselves, a thermal ray transmission glass plate is employed for the outermost window glass plate 46 so as to avoid a temperature rise in the glass plate 46 itself from the thermal radiation energy from the inside.
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