Ampex Corporation

Other

Nathan W Osborn

David R Rodal

Robert B Steele

An end-of-tape detection apparatus provides a constant accumulated total of the revolutions of the supply and takeup reels relative to the true end-of-tape defined by the leader-to-tape splice. Counter means stores a value indicative of the true end-of-tape, and also counts and stores the accumulated total of revolutions as the tape is wound onto a reel. Thereafter as tape is pulled from the reel, the approaching end-of-tape is accurately known in terms of the remaining revolutions of the reel. A microprocessor uses the stored value to determine the point at which deceleration of the tape should begin, whereby the tape rapidly is decelerated to a selected speed just prior to true end-of-tape. The tape is stopped upon sensing the leader-to-tape splice.

Circuit for detecting the end of a tape by counting reel revolutions

Tape guides of a magnetic tape transport machine are controlled during movement by sensing the position of the member as it moves along a defined path in varying velocity corresponding to the position. The member is initially accelerated at a selected rate to a maximum velocity which is then maintained until a distance close to the end position is reached. Velocity is then reduced at a selected rate until another position closer to the end position is reached. At this position a final velocity is maintained until the end is reached. A determination is made of how closely the second distance from the end coincided with reaching the final velocity. The length of the first distance from the end position is adjusted to reduce the difference between the coincidence of reaching the second distance and the final velocity. Further, the sensed final position of the member is retained as the target final position for the subsequent operation.

Method and apparatus for controlling deployment of a tape transport

A digitally controlled motor drive system using a pulse width modulated motor drive receives a desired motor velocity signal and an actual motor velocity signal and it provides a corresponding velocity error signal. The velocity error signal is adjusted in response to a change in the value of a power voltage supplied to the motor. The velocity error signal may be compensated for back electromotive force and/or for static friction in the motor, if desired. The system is simple, reliable and cost effective.

Adaptive digitally controlled motor drive system and method

An optical sensing circuit useful for detecting the end of a moving tape in a tape transport includes a light source and a light sensor which are closely spaced across a gap. The radiation output of the light source is modulated at a selected frequency which is determined by the operating frequency of a frequency detector. In the absence of a light obstruction, such as passage of the tape in the optical path between the light source and the light sensor, the modulated output from the light source is detected by the sensor. The processed signal from the sensor, which is characterized by the modulation frequency, is applied to the frequency detector. The detector recognizes only those signals having the modulated frequency, and does not respond to signals of different frequencies, which may result from impingement of other radiation than that from the light source on the photosensor.

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Menlo Park, CA, United States of America

Nathan W Osborn