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Title: Tape transport reel servomechanism
Claims: The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows: 1. In a tape transport system including a capstan for moving tape past a work station from a supply to a take-up reel and wherein means are provided for forming loops between said capstan and each of said reels, a separate servo system coupled to each of said reels, each servo system comprising: a drive motor coupled to said reel; motor control means including a summing junction for producing a drive motor control signal; means including a pulley engaging said tape between said loop forming means and said reel for producing a position signal proportional to the magnitude of tape movement thereat; means for sensing when said capstan is at rest; and means responsive to said capstan being at rest for applying said position signal to said summing junction. 2. In a tape transport system having a capstan and servomechanism for velocity control of tape across a work station, separate reels and servomechanisms for tape supply and take-up control, and a separate tape loop between each reel and said capstan, a separate combination for each reel and tape loop comprising: means for storing said separate tape loops, each independent of the other; separate means between each tape loop and a different one of said reels for producing a signal proportional to any change in position of a segment of tape at the entrance to said separate loop storage means; and means responsive to said capstan being stopped for applying said signal as a corrective signal to said reel servomechanism. 3. The combination of claim 2 wherein each reel servomechanism includes: a rotor connected to a pulley turned by said tape whenever said tape moves between said reel and tape loop storage means, a stator having a primary winding and a secondary winding, a source of high frequency AC excitation applied to said primary winding, and a rectifier connected to said secondary winding. 4. The combination of claim 3 wherein each reel servomechanism includes means for producing a signal proportional to tape velocity between a different one of said reels and separate loop storage means, said tape-velocity signal means comprising means connected to said secondary winding for discriminating a signal induced by said excitation in said secondary winding proportional to tape velocity over said pulley. 5. In a tape transport system having a supply reel, a take-up reel, and means for driving tape past a work station as tape is transferred from said supply reel to said take-up reel, said system further having means for storing loops of tape between each of said reels and said tape driving means, a separate combination for each reel and loop storing means comprising: a servomechanism for driving said reel in the requisite direction to supply or take up as it is driven by said driving means, means between said reel and said loop storing means for sensing tape velocity and applying a signal proportional to tape velocity to said servomechanism as a stabilizing feedback signal while said tape is being driven, means between said reel and said loop storing means for sensing any change in tape position therebetween, and generating a corrective signal proportional to any change, and means responsive to said tape driving means being idle for applying said signal proportional to change in tape position as a corrective signal to said reel servomechanism. 6. The combination of claim 5 wherein said tape position sensing means is comprised of an angular position sensor having a rotor connected to a pulley turned by said tape whenever said tape moves between said reel and loop storing means and a stator having a primary winding and a secondary winding, a source of high frequency AC excitation applied to said primary winding to induce a signal into said secondary winding, said rotor being of a form that will amplitude modulate the signal induced in said secondary as a function of its angular position. 7. The combination of claim 6 wherein said means for producing said signal proportional to tape velocity is comprised of means connected to said secondary winding for discriminating a signal induced by said excitation in said secondary winding proportional to tape velocity over said pulley. 8. The combination of claim 5 wherein: said tape velocity sensing means is comprised of a tachometer having a metal cup rotor connected to a pulley turned by said tape whenever said tape moves between said reel and loop storing means, and a stator having a primary winding and a secondary winding, a source of high frequency AC excitation applied to said primary winding, means for discriminating a signal induced by said excitation in said secondary winding proportional to tape velocity over said pulley, and said tape position sensing means is comprised of said tachometer and means for rectifying a signal induced in said secondary winding by said excitation to produce said corrective signal. 9. In a tape transport system having a capstan and servomechanism for velocity control of tape across a work station, separate reels and servomechanisms for tape supply and take-up control, and a separate tape loop between each reel and said capstan, a separate combination for each reel and tape loop comprising: means between said reel and tape loop for sensing change in tape position and for applying a corrective feedback signal proportional to said change to said reel servomechanism to stabilize said reel servomechanism while said capstan is stopped, means for providing a feedback signal for said capstan servomechanism that is proportional to capstan velocity, separate means responsive to said capstan velocity feedback signal for generating separate reference signals proportional to the velocity of tape past said capstan, one reference signal for each reel servomechanism, separate means responsive to separate ones of said reference signals for generating ramp signals which increase or decrease at a controlled rate when capstan velocity is changed, and separate means for adding said ramp signals to separate ones of said reel servomechanisms for controlled acceleration and deceleration of said reels. 10. The combination of claim 9 wherein said means for applying said corrective feedback signal proportional to change in position comprises: a rotor connected to a pulley turned by said tape whenever said tape moves between said reel and tape loop storage means, a stator having a primary winding and a secondary winding, a source of high frequency AC excitation applied to said primary winding, and a rectifier connected to said secondary winding. 11. The combination of claim 10 wherein each reel servomechanism includes means for producing a signal proportional to tape velocity between a different one of said reels and separate loop storage means, said tape-velocity signal means comprising means connected to said secondary winding for discriminating a signal induced by said excitation in said secondary winding proportional to tape velocity over said pulley. 12. The combination of claim 9 including: separate means for sensing extent of tape in said separate tape loops, and separate means for controlling a factor of proportionality of respective reference signals in said reference generators in accordance with the extent of tape in respective tape loops. 13. In a tape transport system having a capstan and servomechanism for velocity control of tape across a work station and separate reels and servomechanisms for tape supply and take-up control, the combination comprising: means for providing a feedback signal for said capstan servomechanism that is proportional to capstan velocity, separate means responsive to said capstan velocity feedback signal for generating separate reference signals proportional to the velocity of tape past said capstan to provide one reference signal for each reel servomechanism, separate means responsive to separate ones of said reference signals for generating ramp signals which increase or decrease at a controlled rate when capstan velocity is changed, and separate means for adding said ramp signals to separate ones of said reel servomechanisms for controlled acceleration and deceleration of said reels. 14. The combination of claim 13 including: separate means for storing loops of tape between each reel and said capstan, separate means for sensing the extent of tape stored by each of said loop storing means, and separate means for controlling a factor of proportionality of said reference signals in said reference generators for respective ones of said reel servomechanisms. Other info: Inventors: Gervais, William J. (Van Nuys, CA, US) Matula, Jerry (Culver City, CA, US) Application Number: 505861 Filing Date: 1974-09-13 Publication_date: 1976-05-25 Assignee: Pertec Corporation (El Segundo, CA) Primary Class(es): 242/331.2 Other Classes: US Patent Ref:
Other Refs: Primary Examiner: Christian, Leonard D. Assistant Examiner: Attorney: Lindenberg, Freilich, Wasserman, Rosen & Fernandez |
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