PROCESS AND APPARATUS FOR PROVIDING A TIME DELAY IN THE REPRODUCTION OF INFORMATION STORED ON A CIRCULATING RECORDING MEDIUM

• US 3,576,406 A
• Filed: 02/04/1969
• Issued: 04/27/1971
• Est. Priority Date: 02/14/1968
• Status: Expired due to Term

• Current Assignee: Louis Court, Magnien Patrick
• Original Assignee: Louis Court, Magnien Patrick
• Inventors: Court, Louis, MAGNIEN PATRICK
• Application Number:
  US04/796,483
• Time in Patent Office: 812 Days
• US Class Current: 360/7
• CPC Class Codes: G06G 7/625 for filters; for delay lines measuring characteristics of electric networks, e.g. plotting Nyquist diagram G01R27/28
• CPC Class Codes: G11B 20/225 for reducing wow or flutter by controlling the speed of the record carrier G11B15/46, G11B19/28

Abstract

Method and apparatus of producing an adjustable time-delay in the reproducing of information which is recorded on a magnetic tape, said time-delay being materialized by an open loop upstream of a reproducing head. A signal is recorded on the tape upstream of said loop and simultaneous the measurement of the predetermined time-delay is initiated; the passage of said signal is detected by the reading head and the absolute value and the direction of the time interval which elapses between the end of measurement of said time-delay and the detection are measured. The length of the loop is automatically modified if necessary, by an amount which increases with said absolute value and in a direction corresponding to the reduction of said time interval to zero.

Claims

1. A method of producing an adjustable time-delay in the reading of information recorded on a circulating recording magnetic tape, said time-delay being provided by an open loop in the recording tape upstream of a reading element comprising the steps of recording a signal on the tape upstream of said loop, simultaneously initiating the measurement of the predetermined time-delay, detecting the passage of said signal of the reading element, determining the absolute value and the direction of the time interval between the end of measurement of said time-delay and the detection of the signal, and adjusting the length of the loop responsive to the time interval by an amount which increases with said absolute value and in a direction corresponding to the reduction of said time interval.

2. A method in accordance with claim 1, the amplitude of the adjustment of the length of the loop being proportional to said absolute value in a predetermined range of said absolute values and lower values above and below said range.

3. A device for producing an adjustable time-delay in the reading of information from a circulating recording medium such as a magnetic tape, comprising means for recording a signal on said medium and upstream of an open loop formed with said medium while at the same time triggering a scaler for counting said time-delay, means downstream of the loop for reading the passage of the signal, a comparator assembly for delivering signals representing the time interval which elapses between the detecting of the signal and the end of said adjustable time-delay and the direction thereof, a motor controlling the length of the loop and means controlling the operation of said motor responsive to the amplitude and direction of said time interval for decreasing said time interval.

4. A device in accordance with claim 3, wherein said comparator assembly comprises a comparator which delivers a different signal according to the direction of the time interval which elapses between the instant corresponding to the end of counting by the scaler which is supplied by a clock pulse generator and the instant of passage of the recorded signal in front of the reading means and a pulse integrator which records the number of pulses delivered by the clock pulse generator between the two instants aforesaid and provides the absolute value of the time interval.

5. A device in accordance with claim 3, said control means energizing the motor for rotation at constant speed for a time period which is an increasing function of said time interval.

6. A device in accordance with claim 3, said control means energizing the motor for a constant preadjusted period at a speed which is an increAsing function of said time interval.

7. A device in accordance with claim 3, comprising a threshold circuit interposed between the comparator assembly and the control means for inhibiting energization of said motor when the time interval is smaller than a predetermined value.

8. A device in accordance with claim 3, wherein the length of the loop is modified by a carriage displaced between two stop positions and means for switching the rate of movement of the circulating recording medium as said carriage engages one of said stops.