| 摘要 |
PURPOSE:To eliminate the occurrence of light volume changes due to the difference in heat release so as to improve the quality of images by deciding timings when a group of illuminating elements disposed in a non-recording interval are totally switched on an when they are totally switched off, respectively, on the basis of a vertical synchronizing signal of a video signal, and by switching on the individual illuminating elements totally or individually in synchronism with the decided timings. CONSTITUTION:In a case where full illumination is effected in an interval l2 that is a non- recording interval, i.e., during time T2, since a LED 73A per se is mounted on a metal substrate 92 having heat-radiating fins provided for the purpose of cooling, and since a LED element that has been kept switched on heretofore, i.e., a LED heated to a high temperature, became saturated at a predetermined temperature, while a LED that has been kept switched off heretofore, i.e., a LED heated to a low temperature, is heated close to its saturation temperature during the time T when the full illumination is conducted, the difference in temperature between the two LEDs decreases. Therefore, the difference in temperature between LED elements corresponding, respectively, to a recording portion and non-recording portion is caused to relatively decrease in the LED line head 73 by conducting the above illuminating control in the non-recording interval, thereby preventing the deterioration of images due to the light volume changes occurring in an exposure means employing LED elements. |
