| 摘要 |
PURPOSE:To decrease the cost of the titled device by adding a comparator circuit and a storage time converting circuit so as to control the charge storage time in response to an output level of a CCD thereby adjusting automatically the output level of the CCD to a prescribed value in place of the automatic control of luminescent luminous amount through the change in an input current of a fluorescent light. CONSTITUTION:When a pseudo white level voltage VW is lower than a reference voltage VS, an output level from a comparator circuit 14 is at a low level and a frequency of a transfer gate pulse PTG from a voltage frequency converting circuit 15 is low. Thus, the period of the transfer gate pulse PTG gets longer and a level of a reference white level signal VF of a CCD11 is higher. When the level of the reference white level signal VP gets higher, an output level of the comparator circuit 14 goes to a high level, the frequency of the transfer gate pulse PGT gets higher, the period is shorter and the level of the reference white level signal VF from the CCD11 is lower. Thus, the level of the reference white level signal VP is adjusted automatically to a prescribed value.
|
