SERVO CONTROL IN TAPE DRIVES
First Claim
1. Servo apparatus for a tape drive having a read/write head for reading and writing data on magnetic tape having at least one servo track for providing transverse position information, the servo apparatus comprising:
- at least two servo readers associated with the read/write head, each servo reader being arranged for reading said at least one servo track during read/write operations, the servo readers being operative concurrently to generate respective servo read signals;
a position estimator for processing each servo read signal to generate a series of position values each corresponding to a respective time instant, the position values being indicative of transverse position of the associated servo reader; and
a servo controller for calculating from said position values and time instants (i) a skew value indicative of tape skew relative to the read/write head and (ii) a tension variation value indicative of variation of tape tension from a reference value;
wherein said servo controller is adapted to account for cross-coupling between tape skew and tension variation in calculating the skew and tension variation values.
1 Assignment
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Accused Products
Abstract
Servo control methods and apparatus for a tape drive. A read/write head reads and writes data on magnetic tape with at least one servo track providing transverse position information. At least two servo readers arranged for reading a servo track associated with the read/write head operate concurrently to generate servo read signals. A position estimator processes each servo read signal to generate a series of position values corresponding to respective time instants indicative of their transverse positions. A servo controller calculates a skew value indicative of tape skew relative to the read/write head and a tension variation value indicative of variation of tape tension. The servo controller is adapted to account for cross-coupling between tape skew and tension variation.
58 Citations
20 Claims
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1. Servo apparatus for a tape drive having a read/write head for reading and writing data on magnetic tape having at least one servo track for providing transverse position information, the servo apparatus comprising:
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at least two servo readers associated with the read/write head, each servo reader being arranged for reading said at least one servo track during read/write operations, the servo readers being operative concurrently to generate respective servo read signals; a position estimator for processing each servo read signal to generate a series of position values each corresponding to a respective time instant, the position values being indicative of transverse position of the associated servo reader; and a servo controller for calculating from said position values and time instants (i) a skew value indicative of tape skew relative to the read/write head and (ii) a tension variation value indicative of variation of tape tension from a reference value; wherein said servo controller is adapted to account for cross-coupling between tape skew and tension variation in calculating the skew and tension variation values. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A tape drive, comprising:
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a read/write head for reading and writing data on magnetic tape having at least one servo track for providing transverse position information; a drive system for effecting movement of the tape relative to the read/write head; at least two servo readers associated with the read/write head, each arranged for reading said at least one servo track during read/write operations, the servo readers being operative concurrently to generate respective servo read signals; a position estimator for processing each servo read signal to generate a series of position values, corresponding to respective time instants, indicative of transverse position of the associated servo reader; a servo controller for calculating from said position values and time instants (i) a skew value, indicative of tape skew relative to the read/write head, and (ii) a tension variation value indicative of variation of tape tension from a reference value, wherein the servo controller is adapted to account for cross-coupling between tape skew and tension variation in calculating the skew and tension variation values; a tension adjustment mechanism for adjusting tape tension in dependence on said tension variation value; and a skew adjustment mechanism for adjusting tape skew relative to the read/write head in dependence on said skew value. - View Dependent Claims (12)
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13. A servo control method for a tape drive having a read/write head for reading and writing data on magnetic tape with at least one servo track for providing transverse position information, the method comprising the steps of:
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reading at least one said servo track during read/write operations concurrently with at least two servo readers associated with the read/write head to generate respective servo read signals; processing each servo read signal to generate a series of position values, corresponding to respective time instants, indicative of transverse position of the associated servo reader; and calculating from said position values and time instants (i) a skew value, indicative of tape skew relative to the read/write head, and (ii) a tension variation value indicative of variation of tape tension from a reference value; and accounting in said calculating step for cross-coupling between tape skew and tension variation. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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Specification