| 摘要 |
PURPOSE:To shorten the light quantity rise time of a light source at low cost by providing a detecting means which detects the quantity of light of the light source reaching a set value and a sequence control means which starts an exposure scan on an original after the set value is detected. CONSTITUTION:A photodetecting element 13 detects the quantity of light of a fluorescent lamp 3 and a light quantity control circuit 14 receives the output of the photodetecting element 13 to control the quantity of light of the fluorescent lamp to the specific set value. A high frequency stabilizer 15 receives a signal from the light quantity control circuit 14 and supplies a controlled tube current to the fluorescent lamp 3. A light quantity startup detection circuit 17 receives the signal from the light quantity control circuit 14 and detects the quantity of light at the startup of the fluorescent lamp 3 reaching the specific value or the specific rate of the specific set value, thereby transmitting its startup detection output to the sequence control circuit 16. Consequently, the sequence control circuit controls the forward movement of a platen 2. thus, the light quantity rise time of the light source is shortened at low cost. |
