| 摘要 |
PURPOSE:To dim light through software and to simplify constitution by detecting the voltage across an exposure lamp by the transformer of a voltage feedback part, generating a trigger pulse by a microcomputer according to the detected voltage, and then controlling a thyristor. CONSTITUTION:The exposure lamp 4 is connected to an AC power source 21 through the bilateral thyristor 22 and the feedback transformer 23 is provided to the voltage feedback part. The voltage across the exposure lamp 4 is detected by the transformer 23 and converted by a rectifier 24 into a DC voltage, which is digitized by an A/D converter 29 and sent to the microcomputer 31. The microcomputer 31 operates its timer according to the level of the input data to generate a trigger pulse, with which the turn-on angle of the thyristor 22 is controlled to control the voltage applied across the exposure lamp 4. Thus, the light dimmed through software an the constitution is simplified. |
