| 摘要 |
PURPOSE:To eliminate the gain fluctuation, by holding a certain duty of a transfer drive pulse as well as the duration of a sampling pulse and a transfer gate pulse. CONSTITUTION:If the duration talpha of a sampling pulse phis is fixed, the charge quantity that is charged from ID to a G2 gate F during a sampling is fixed. The time from an off of the pulse phis to an open of a transfer gate phit does not vary the CCD output voltage V0. If the on-time tr of the pulse phit to be supplied to the gate phit is set constant, the effective time to be transferred from the gate F to the gate phit becomes constant. As a result, a transfer charge 20b is also set constant regardless of fs. Thus the sum Vo of the signal voltage at the CCD output part and the offset component becomes constant. The signal amplitude of the output part becomes constant to a sine-type analog signal and regardless of fs. In this case, the duty ratio is set constant to the cycles of transfer pulses phi1 and phi2, and accordingly the duty ratio is kept constant between the holding width and the cycle of the output signal that is produced in the timing of off of phi1 or phi2. This means that no gain fluctuation is caused. |
