Patent Number: 6,305,629

Title: Servo error detection of bi-directional reel-to-reel tape drives using fine line tachometers

Abstract: Servo errors can be avoided in a bi-directional reel-to-reel tape transport in which magnetic tape is moved in either of two opposite directions for data recording by providing a fine-line tachometer for each reel and a directly coupled tension sensor. Control of tape speed is implemented in a servo algorithm that uses tachometer inputs to determine parameter values for generating reel motor drive currents. If the linear velocity of both reels is the same then the tension output must be within a tolerable range. The directly coupled tension output provided an is indication of the actual current of the tension sensor. The difference between the linear velocities of the tape from each reel is calculated and monitored together with the tape tension. A trip level is set when an error occurs to stop tape motion and permit recovery without damaging the tape. The status of each outputs indicates the status of the tape velocity and whether the tape is slack or stretched on one reel which could cause a servo error which must be detected in order to prevent chopped blocks of data or data slivers. Motor problems may also be detected using the invention.

Inventors: Chliwnyj; Alex (Tucson, AZ), Stouffer; Colleen Renee (Tucson, AZ), Wills; Steven Carter (Tucson, AZ)

Assignee: International Business Machines Corporation

International Classification: G11B 15/43 (20060101); G11B 5/584 (20060101); B65H 059/38 (); G03B 021/50 (); G11B 015/46 (); G11B 023/42 ()

Expiration Date: 10/23/2018