| 摘要 |
PURPOSE:To regulate easily the loop characteristics, by comparing the input signal applied to an input terminal to an end of a prescribed separated part of a servo loop with the synthetic signal of said input signal and the output signal of an oscillator through a buffer circuit and a rectifying circuit. CONSTITUTION:A prescribed part of a focus servo loop is separated, and a terminal 31 is connected to this separated part. A focus signal Si is sent to a buffer circuit 43 via an operational amplifier 32, and at the same time a measuring frequency signal Ss is delivered from an oscillator 36 and synthesized with the signal Si via operational amplifiers 37 and 35 and sent to a buffer circuit 42. The outputs of circuits 42 and 43 are sent to a comparator 48 via BPF44 and 45 and rectifier circuits 46 and 47. Then the difference of the peak-to-peak value between the signal Si and the output signal So of the terminal of a servo amplifier 41 is fed to a null meter 49. This difference is measured to regulate easily the servo loop characteristics. |
