| 摘要 |
A digital servo circuit, for example for a video tape recorder, for controlling the velocity and the phase of a capstan which is driven by an electric motor. The circuit includes a frequency generator for generating a pulse signal having a repetition rate that varies in accordance with the velocity of the capstan, an n-bit counter for counting a reference clock signal during an interval corresponding to the repetition rate of the pulse signal, a latch circuit for latching the least significant m bits output of the counter (m is less than n), a control circuit for controlling the m-bits output from the latch circuit so as substantially to hold the latter output at the minimum level when the n-bits output from the counter is less than a first predetermined value, and at the maximum level when the n-bits output from the counter is more than a second predetermined value, and a digital-to-analog converter for converting the m-bits output from the latch circuit to the corresponding analog signal to drive the motor. |
