Tandberg Data Asa

Georg Boasson

Erik N Hardeng

A speed servo control for a tape drive comprising a take up reel having tape wound therearound, the tape extending to a supply reel and wound therearound. A flutter roller is arranged to press said tape that extends between the take up reel and the supply reel to rotate with circulation of the tape. A first tachometer is connected to said take up reel to rotate therewith. A second tachometer is connected to the flutter roller to rotate therewith, the first and second tachometers connected to a servo system for controlling the speed of the take up reel drive motor according to the select speed of the tape. The second tachometer from the flutter roller normally controls the servo for controlling the take up reel speed. A mechanism is provided for ignoring a tachometer signal from the second tachometer and controlling using the first tachometer, until the tape is tensioned against the flutter roller after start up. The mechanism for ignoring is advantageously a third tachometer connected to the supply reel and a pulse detector sensing pulses from the third tachometer and signal connected to the switch such that when a certain number of tachometer pulses are sensed from the third tachometer, or a certain stable frequency of pulses is sensed from the third tachometer, the switch is switched from the first tachometer (take up reel) as input, to the second tachometer (flutter roller) as input to the servo system.

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Oslo, Norway

Georg Boasson