Document Type and Number:
Japanese Patent JPS4918806
Kind Code:
B1
Abstract:
1301094 Control of A.C. motors RCA CORPORATION 13 March 1970 [21 March 1969] 14946/69 Heading H2J [Also in Division G3] A servo system, for controlling the velocity and phase of a rotatable member, includes a device for sensing the power supplied to drive the member. When the power falls below a given level, but a frequency and phase error signal remains, the device causes reversal of the sense of the power supplied in order to provide positive deceleration of the member. In the embodiment shown, a magnetic headwheel 8 is driven by a polyphase synchronous motor 14, in a record-reproduce system. A tone-wheel 16 generates pulses representing the rotation of the wheel 8, and these pulses are compared in a detector 22 with a video reference signal 24 to produce an error signal which in turn controls the power supplied to the motor 14. The reference signal 24 also provides an input to a generator 38 which produces a triangular waveform for modulation by the error signal in a circuit 46 which produces two related square pulse trains for each phase of the 3-phase input. A sensor 104 detects the width of these pulses, representing the power supplied to the motor 14, and, if the power falls below a preset level, actuates a switch control 100 to rearrange the signals supplied to the motor in such a way as to tend to reverse its direction of motion. The sensor 104 will subsequently again detect a low power condition and return the drive supply circuit to its normal operating arrangement.
Application Number:
JP2344870A
Publication Date:
May 13, 1974
Filing Date:
March 19, 1970
Export Citation:
International Classes:
G05D13/62; G11B15/18; G11B15/46; G11B15/473; H02P7/06; H02P27/06; H02P29/00; (IPC1-7): G05D13/64