| 摘要 |
PURPOSE:To enable constant illuminating light to be obtained with a simple constitution according to the change in the quantity of light without decreasing the utilization rate of light from a light source by controlling the reflecting position of a reflecting plate with a slit illuminating device using a fluorescent lamp as an illuminating light source. CONSTITUTION:When the quantity of light from a light source 4 lowers and the output of a detector 5 becomes lower than a reference level, the deviation output of a comparator 601 becomes positive. Here, the output positive of the comparator 601 is inputted to a reversible motor 9 via driving circuit 8, which then moves a reflecting plate in the positive direction, thus automatically correcting the output of the detector 5 so that it coincides with the reference level. When the output of the detector 5 increases, the reverse controlling takes place. The gate 602 provided between the comparator 601 and driving circuit 8 is held ON delay for a fixed time in consideration for the transient phenomenon of the rise of the light source 4, whereby misdetection is prevented. In this way, a constant quantity of light may be obtained with the simple constitution according to the change in the quantity of light. |
