| 摘要 |
PURPOSE:To increase the reliability of a solid state scanner, by detecting the fluctuation of light volume by a unit of light volume sensor and then normalizing the picture signal according to the change of light volume as well as performing the display of alarm and the discontinuation of functioning in case the light volume is reduced. CONSTITUTION:The light volume of a light source is detected by light volume sensor 10, and the detection signal is supplied to an error amplifier 11. A certain reference value Vr1 set previously is supplied to the amplifier 11, and the differece to the input signal is delivered in the form of an error signal ER to be supplied to a voltage control amplifier 13 as well as to cmparators 14 and 15. For the amplifier 13, the amplification factor decreases and increases as the error signal decreases and increases respectively. Then the amplifier 13 normalizes the picture signal PS and then delivers it. At the same time, the error signal is compared with reference values Vr2 and Vr3 decided by comparators 14 and 15 respecitvely. The ''1'' is delivered when the signal ER is larger than the values Vr2 and Vr3; and the display of alarm and the discontinuation of functioning are carried out when the light volume becomes less than the prescribed value. |
