| 摘要 |
982,146. Automatic speed control. FERNSEH G.m.b.H. July 19, 1961 [July 20, 1960, No. 26138/61., Heading G3R. In apparatus for controlling the instantaneous angular position of the rotor of an electric motor, a first series of pulses representative of the motor speed are compared with a reference series of pulses in a phase discriminator producing a control voltage, and this control voltage together with its differential with respect to time is fed to means for adjusting the angular position of the rotor. As shown, apparatus for recording video signals on magnetic tape comprises a motor 10 driving a transducer head assembly 80. Signals proportional to the speed of motor 10 are derived from a photo-cell 30 illuminated by light reflected from a black-and-white patterned disc 20, and are fed to a phase comparison circuit 50 where they are compared with synchronizing pulses 40 to develop a control signal which is applied to a circuit 60 providing an output signal including a component proportional to its differential with respect to time. These combined components are applied to vary the frequency of a generator 70 supplying the motor 10. Several arrangements suitable for the circuit 60 are described (Figs. 4a to 8, not shown). The output signal from circuit 60 may control an eddy-current brake associated with the motor 10. When the apparatus is used in connection with the reproduction of signals from a magnetic tape (Figs. 10 and 11, not shown), the phase discriminator 50 is fed with the horizontal synchronizing pulses contained in the signal reproduced from said tape and with pulses produced by a synchronizing generator. |
