| 摘要 |
A copying machine having a fluorescent lamp as a light source for illuminating an original document. The copying machine comprises a lamp control system connected to an optical sensor for detecting light intensity of the lamp. The lamp control system is operable for maintaining the tube wall temperature of the lamp constant during a standby period prior to a copying operation. This lamp control system continues power supply or supplies power at a high level to the lamp while the light intensity detected by the sensor is on the increase, and interrupts the power supply for a predetermined period or supplies power at a low level to the lamp following a decrease in the light intensity.
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