| 摘要 |
PURPOSE:To improve S/N of a picture signal, by controlling the reference level of an amplifying part on a basis of the level of the signal of a bit corresponding to a dummy bit and compensating the influence due to the temperature characteristic etc. of a CCD shift register. CONSTITUTION:Electric charge stored in a photodiode group 2 is transferred to corresponding bits of shift registers 4a and 4b through charge transfer element groups 3a and 3b and is shifted and is outputted to the first-stage amplifying part 11. Shift registers 4a and 4b are provided with dummy bits which are not connected to charge transfer element groups 3a and 3b directly, and a signal of the dummy bit part in the output signal of the first-stage amplifying part 11 passes through an analogue switch 21 and is integrated by a voltage holding circuit 18. The output signal of the voltage holding circuit 18 is inverted by an inverting circuit 25 and is inputted to the non-inversion input terminal of an operational amplifier 12 constituting the first-stage amplifying part 11 to control the reference voltage, thus compensating degradation of S/N of the picture signal. |
