Speed and phase control system

• US 4,086,520 A
• Filed: 02/19/1976
• Issued: 04/25/1978
• Est. Priority Date: 10/01/1973
• Status: Expired due to Term

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Moriya, Ryusuke, Hashizaki, Kazuo
• Primary Examiner(s): Schaefer, Robert K.
• Assistant Examiner(s): Duncanson, Jr., W. E.
• Application Number:
  US05/659,363
• Time in Patent Office: 796 Days
• Field of Search: 318/268, 318/269, 318/310, 318/311, 318/314, 318/318, 318/329, 318/603
• US Class Current: 318/269
• CPC Class Codes: H02P 23/183 of one shaft without controlling the prime mover

Abstract

In an apparatus having at least one rotary head for reproducing video signals recorded in successive parallel tracks extending obliquely across a tape which is advanced longitudinally and also has control signals recorded therein in predetermined positional relationship to the respective record tracks to be reproduced by a fixed transducer or head with a repetition rate that is dependent on the speed of advancement of the tape: a speed and phase control system for the rotary head or heads has a rotational speed detector for producing pulse signals representative of the rotational position of each rotary head and having a repetition rate that is a function of the rotational speed of the rotary head; a phase comparator for producing a phase responsive signal having a voltage level that is varied in response to changes in the relative timing of the reproduced control signals and the pulse signals; a digital device for producing a speed responsive signal having a voltage level that generally corresponds to the repetition rate of the pulse signals, but which is varied in response to changes in the repetition rate of the pulse signals only when such changes occur without corresponding changes in the repetition rate of the reproduced control signals; and a brake or other means for controlling the rotation of the rotary head in response to the voltage levels of the phase responsive signal and the speed responsive signal. In a preferred embodiment, the digital device for producing the speed responsive signal includes a source of clock pulses, a counter for counting the clock pulses for time intervals determined by the repetition rate of the pulse signals from the rotational speed detector, a digital-analog converter for converting the count of the counter, at the end of the mentioned time intervals, to a corresponding voltage level of the speed responsive signal, and an arrangement for establishing the initial count of the counter at the commencement of each of the time intervals in dependence on the repetition rate of the reproduced control signals.

Claims

1. In an apparatus for reproducing information signals recorded in successive parallel tracks on a record medium along with respective control signals recorded on the record medium in predetermined positional relationship to said tracks, and in which the apparatus includes rotary transducer means for scanning said tracks in succession so as to reproduce the information signals recorded therein as the record medium is advanced, and fixed transducer means for reproducing said control signals with a repetition rate that is dependent on the speed of advancement of the record medium:

a speed and phase control system for said rotary transducer means comprising rotational speed detector means for producing pulse signals representative of the rotational position of said rotary transducer means and having a repetition rate that is a function of the rotational speed of said rotary transducer means;

phase comparison means for producing a phase responsive signal having a voltage level that is varied in response to changes in the relative timing of said reproduced control signals and said pulse signals;

means for producing a speed responsive signal including a source of clock pulses, counting means for counting said clock pulses for time intervals determined by said repetition rate of said pulse signals from the rotational speed detector means, means for converting the count of said counting means, at the end of each of said time intervals, to a corresponding voltage level of said speed responsive signal, and means for establishing the initial count of said counting means at the commencement of each of said time intervals in dependence on said repetition rate of said reproduced control signals so that the voltage level of said speed responsive signal is varied in response to changes in said repetition rate of the pulse signals only when said changes occur without corresponding changes in said repetition rate of the reproduced control signals; and

means for controlling the rotation of said rotary transducer means in response to the voltage levels of said phase responsive signal and said speed responsive signal.

2. An apparatus according to claim 1;

wherein said means for controlling the rotation of said rotary transducer means comprises braking means for braking said rotary transducer means.

3. An apparatus according to claim 2;

wherein said means for controlling the rotation of said rotary transducer means further comprises an adder connected to said phase comparison means and to said means for converting the count of said counting means, the output of said adder being connected to said braking means for regulating the latter.

4. An apparatus according to claim 1;

wherein said counting means includes a first digital counter, and said means for converting the count includes a digital-analog converter.

5. An apparatus according to claim 4;

wherein said means for establishing the initial count of said counting means includes a second digital counter for counting said clock pulses for time intervals determined by said repetition rate of said reproduced control signals and correspondingly establishing said initial count of the first digital counter.

6. An apparatus according to claim 1;

in which the record medium is in the form of a tape which is advanced longitudinally and has said successive parallel tracks extending obliquely thereacross, said information signals are video signals having predetermined intervals thereof recorded in said successive tracks, respectively, said rotary transducer means includes a rotary drum having the tape guided in a helical path about a portion of the drum periphery and at least one reproducing head on said drum to repeatedly scan across the tape in said path, and said means for controlling the rotation of the rotary transducer means includes braking means for braking the rotation of said drum and each said head and an adder receiving said phase responsive signal and said speed responsive signal for producing a brake control signal by which the braking force of said braking means is regulated.