Dynamic magnetic information storage or retrieval – Automatic control of a recorder mechanism – Controlling the head
Patent
1982-08-16
1984-12-11
Kilgore, Robert M.
Dynamic magnetic information storage or retrieval
Automatic control of a recorder mechanism
Controlling the head
318571, 360 77, G11B 2108, G11B 2110, G05B 1925
Patent
active
044881894
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
This invention relates to data storage devices using sector servo wherein data and servo information are arranged in parallel tracks composed of sectors and more particularly to a seek control system for moving the transducer assembly from one track location to another track location.
2. Background Art
Sector servo for rotating data storage devices is well known, but not widely used. The four track wide capture area and three track linear capture area of U.S. patent application, Ser. No. 277,764 filed June 26, 1981, now U.S. Pat. No. 4,400,747, is used to implement the technique of the present invention. Prior sector servo systems have utilized control techniques that cause the generated servo information to simulate the position error signal that would be obtained from a dedicated servo surface. The use of continuous simulated servo information has the disadvantage of requiring the extra steps of generating the signal. These steps also add to the complexity and cost of the circuits required and probably decrease reliability.
DISCLOSURE OF INVENTION
In accordance with the present invention, a seek operation control effectively controls input to the drive coil during access, which applies drive to the transducer assembly and also projects where the transducer will be when the next sector information is received.
The method and apparatus of the invention samples the servodata of each servo sector to provide samples which occur more than 3,000 times per second. During each servo time of a seek operation, the transducer travel between the two immediately preceding servo signals is used to generate a projected position for the next sample time which is truncated to indicate one of four track types. At the next sector time sample, the error signal is added to the truncated value to produce the current actual position from which the velocity and sector time transducer travel is derived and the next position generated. The sector travel is subtracted from the "tracks to go" register value to maintain a continuous record of transducer position and the number of tracks yet to be crossed during the seek operation. The system is tolerant of missing sectors by supressing the error signal and truncated position while using in place thereof, the projected position. Thus an error condition can be tolerated for several sector times before any possibility exists that the next sector signal will not restore the correct current actual position.
BRIEF DESCRIPTION OF THE DRAWINGS
The details of the invention will be described in conjunction with the accompanying drawings in which
FIG. 1 is a block diagram showing the projection of sector time position and correction to achieve the actual present location using the position error signal;
FIG. 2 is a block diagram showing the recording of remaining tracks during the seek operation and drive control;
FIG. 3 is a graphic representation of acceleration and deceleration values;
FIGS. 4A through 4E comprise a flow chart showing the steps of the seek control technique; and
FIG. 5 shows a sector servo technique for identifying one of four adjacent tracks while generating a position error signal representative of the deviation from the track centerline.
BEST MODE FOR CARRYING OUT THE INVENTION
Referring to FIG. 1, an analog position error signal is communicated to the analog to digital converter 10 where at time T0 the value is latched in a five bit register 11. The output register 11 of A/D converter 10 is received as an input of the select circuit 12 and normally becomes the circuit output. If however a signal appears on missing sector line 14, indicating that a sector has been missed, the output of selection circuit becomes 5 zero bits to prevent an error correction.
During the previous cycle the last sector projected position was latched in register 15 at T5 time. The last sector projected position is truncated and rounded to a whole number indicative of the track type by circuit 17 and latched in the output register. The two lines 18 from the
REFERENCES:
patent: 4030132 (1977-06-01), Iftikar
patent: 4103314 (1978-07-01), Case
patent: 4217612 (1980-08-01), Matla
patent: 4297734 (1981-10-01), Laishley
patent: 4400747 (1983-08-01), Siverling
R. K. Oswald-"Head Positioning Servo Design for IBM 3344/3350 Disk Files", IEEE Transactions on Magnetics, vol. MAG-14, No. 4, pp. 176-177, publ. Jul. 1978.
B. McKnight-"A Track Locating Servo System Utilizing the Data Heads as Absolute Position Transducers", IEEE Transactions on Magnetics, vol. MAG-14, No. 4, pp. 182-184, publ. Jul. 1978.
Axmear Frederick E.
Baxter Duane W.
Saxman John H.
Siverling Michael M.
International Business Machines - Corporation
Kilgore Robert M.
Lahtinen Robert W.
LandOfFree
Sector servo seek control does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Sector servo seek control, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Sector servo seek control will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1466891