| 摘要 |
PURPOSE:To improve and stabilize the quality of a read picture, by keeping the brightness of a fluorescent lamp used for the document reading light source of a facsimile equipment, at a regulated level by a feedback control. CONSTITUTION:A lightening power source circuit 13 converts a DC power source to a high frequency by an oscillation circuit at an inverter circuit, and supplies a high frequency current to a fluorescent lamp 11. A photosensor 12 outputs a DC voltage corresponding to the brightness of the fluorescent lamp 11. The circuit 13 has a reference DC voltage in its inside, and compares the output of the photosensor 1 with it, and keeps the brightness of the fluorescent lamp at the regulated level, by increasing a driving current for the fluorescent lamp when the output of the sensor is lower than the reference DC voltage, and decreasing it when the former is higher than the latter. By constituting a device in such way, the quality of the picture can be improved and stabilized.
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