Title: Tape transport system including a logical network for producing quadrature pulse trains and motor control utilizing same

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Claims: What is claimed is:

1. A constant speed reel-to-reel tape transport system, comprising: a tape drive reel; a tape supply reel; a drive motor driving the drive reel; said drive motor including a pair of quadrature windings; motor supply means producing a pair of square-wave motor-drive pulse trains of the same repetition rate, but 90.degree. out of phase, and supplying one train to each of the quadrature windings of the drive motor to control its speed in accordance with the repetition rate of the pulse trains; and control means responsive to the change in the effective radius of one of said reels for varying the repetition rate of said pulse trains, and thereby the speed of the motor, to maintain a constant linear tape speed.

2. A system according to claim 1, wherein said control means is responsive to the change in the effective radius of the drive reel for varying the repetition rate of the pulse trains in inverse proportion to the change in effective radius of the drive reel.

3. A system according to claim 2, wherein said control means comprises a digital counter counting the number of pulses supplied to the drive motor and producing thereby a digital count corresponding to the number of revolutions of the drive reel, a digital-to-analogue converter producing an analogue signal corresponding to said digital count, and means varying the repetition rate of the pulse trains in inverse proportion to said analogue signal.

4. A system according to claim 3, wherein said last-named means comprises an external oscillator, a monostable oscillator driven thereby, means applying said analogue signal to said monostable oscillator to obtain an output therefrom inversely proportional to said digital count, a voltage-controlled-oscillator, and means controlling the frequency of said voltage controlled-oscillator in accordance with said last named signal.

5. A system according to claim 1, wherein said motor supply means comprises; means producing a first pulse train of a repetition rate and pulse width in accordance with the desired speed of the motor, and circuit means producing from said first pulse train said pair of motor-drive pulse trains each having one-half the repetition rate and double the pulse width of said first pulse train.

6. A system according to claim 5, wherein said circuit means comprise: a triggering flip-flop connected to receive at its input said first pulse train and to produce said second pulse train at one of its outputs; a first NAND-gate having a pair of inputs and an output; an OR-gate having a pair of inputs and an output; means supplying said first pulse train and said second pulse train to the pair of inputs of said first NAND-gate and to the pair of inputs of said OR-gate; a second NAND-gate having a pair of inputs and an output; and means supplying the outputs of said first NAND-gate and said OR-gate to the pair of inputs of said second NAND-gate to produce said third train of pulses at the output thereof.

7. A system according to claim 1, wherein said drive motor is a hysteresis synchronous motor.
Other info:

Inventors: Sargunar, John E. (Glenrothes, SC, US)

Application Number: 456239
Filing Date: 1974-03-29
Publication_date: 1976-02-17
Assignee: Burroughs Corporation (Detroit, MI)
Primary Class(es): 242/334.3 242/414.1, 318/6
Other Classes:
US Patent Ref:

3297266	Jan, 1967	Rumple	242/186.
3373332	Mar, 1968	Olsen	242/75.
3764087	Oct, 1973	Paananen et al.	242/191.

Other Refs:
Primary Examiner: Christian, Leonard D.
Assistant Examiner:
Attorney: Barish; Benjamin J., Uren; Edwin W., Peterson; Kevin R.