Control apparatus capable of improving a rise time characteristic of a light source

摘要

An image input apparatus comprises a cold cathode tube light source and a solid imaging device. The image input apparatus reads an image from a document paper by receiving at the solid imaging device a reflected light which is obtained by reflecting a light of the cold cathode tube light source on the document paper. On putting cold cathode tube light source into an on-state, an inverter control circuit controls an inverter to make the inverter supply the cold cathode tube light source with an overcurrent higher than a predetermined tube current which is for use in continuously and stably irradiating a predetermined luminous energy from the cold cathode tube light source. After the overcurrent is applied to the cold cathode tube light source during a predetermined duration, the inverter control circuit controls the inverter to make the inverter reduce the overcurrent to a predetermined current in accordance with an output of the solid imaging device.