Claims
- 1. A technique for providing improved head-position (error) information to a prescribed Head-positioning Servo system, this technique comprising:
- deriving head-position read-back signals from a prescribed Read/Write transducer, these signals including a time-variant position-error component V.sub.1 and a noise component V.sub.c ;
- time-differentiating this signal and applying the raw signal, along with this time-differentiated version, to a "second order summing filter stage", including output-summing means.
- 2. Method of claim 1 wherein the raw signal is passed through a second order low pass filter stage;
- the time-derivative is passed through a second order low pass filter stage and, in parallel, also through a suitable second order band pass filter stage; and summing the outputs of all stages.
- 3. A technique for determining the noise-free value of a system signal which is time variable and has a noise component as detected, this technique involving:
- processing the (as detected) noise-including signal and passing it, plus a "time-derivative version" thereof, through "Second Order/Summing" filter means.
- 4. The method of claim 3 wherein the signal reflects magnetic head position; and the technique is part of track-following servo system.
- 5. The method of claim 4 where the "track-following servo" is part of a transducer positioning means in a high density disk file adapted to secure superior head-displacement error values which are more noise-free.
- 6. The method of claim 5 where a pair of first values V.sub.a, V.sub.b are secured by detecting motor current sense voltage V.sub.i, integrating it with respect to time and passing the result through a pair of novel "second order filter" means--one band-pass (F.sub.1), the other low-pass (F.sub.2); while also securing a third value V.sub.c by detecting position-error signal voltage, including noise components in the usual manner and passing it through a "second order low-pass" filter F.sub.3 ; then algebraically summing all filter outputs to secure a relatively noise-free position error signal V.sub.xo, where:
- [V.sub.xo =V.sub.a +V.sub.b +V.sub.c ];
- whereby the summing filter array gates the position-error voltage but attenuates the noise component.
- 7. The method of claim 6 where filters F.sub.1, F.sub.2 are centered at a prescribed frequency W.sub.o and are characterized by a prescribed "quality factor Q".
- 8. The method as recited in claim 1 as adapted, in a track-following servo in a disk drive for a high-density disk file, for determining relatively noise-free head-position-error signals (X.sub.o).
- 9. The method as recited in claim 8 wherein the method includes:
- providing circuit means to automatically process prescribed noise-including position-error signals (X.sub.i) and motor current signals with second order summing filter means operating at a prescribed center-frequency to implement a prescribed transfer function.
- 10. The method as recited in claim 9 wherein a first "second-order" filter means F.sub.1 is arranged and adapted to receive said motor current signals, and a second "second-order" filter means F.sub.2 is arranged and adapted to receive position-error signals X.sub.i ; and
- wherein summing means is arranged to receive the outputs of said first and second filter means and, summing them, provide the relatively noise-free position-error signals (X.sub.o).
- 11. The method as recited in claim 10 wherein the motor current signals comprise motor current sense voltage values V.sub.i ;
- wherein the first filter means is selected and arranged to comprise time-integrator means coupled to feed a pair of second-order filter stages connected in parallel to said summing means.
- 12. The combination as recited in claim 11 wherein the first filter stage comprises a band-pass filter and a low-pass filter; wherein the second filter means comprises a low-pass filter; and wherein the position-error signals X.sub.i comprise noise-including position-error voltage values; while the summing means is adapted to generate noise-free position-error voltage signals V.sub.xo.
- 13. The technique of claim 3 as implemented in a track-following servo arrangement for high-density disk files, wherein position-error determining means is provided and operated according to a "second order summing filter" array;
- wherein motor current sense voltage V.sub.i is integrated and processed, in parallel, by "second order band-pass" filter means F.sub.a and also by "second order low pass" filter means F.sub.b ;
- while a complex position error signal voltage V.sub.xi, including a mechanical noise component, is processed by a "second order low pass" filter means F.sub.c ;
- whereupon the three filter outputs are summed to generate an improved head-position-error value as position-error voltage, V.sub.xo, relatively free of noise.
- 14. The technique as recited in claim 13 wherein circuit means are provided to automatically implement the "transfer function" between motor current sense voltage V.sub.i and the output V.sub.xo of the summing filters F.sub.a, F.sub.b, F.sub.c.
- 15. The technique as recited in claim 14 wherein the filtering is conducted at 600 Hz center.
- 16. The technique as recited in claim 15 wherein the circuit is implemented using an LSI switching capacitor state variable filter integrated circuit.
Parent Case Info
This is a division of application Ser. No. 543,688 filed Oct. 20, 1983.
US Referenced Citations (11)
Foreign Referenced Citations (1)
Number |
Date |
Country |
52-64577 |
May 1977 |
JPX |
Divisions (1)
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Number |
Date |
Country |
Parent |
543688 |
Oct 1983 |
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