Method and apparatus for rewriting on a magnetic disk on which data has been written by another apparatus having half the track density capability of the first apparatus

Claim 3

The method of claim 1 wherein the read/write head of the head assembly is maintained in operation in an erase mode along with the pair of erase heads during the partial erasure of the data tracks.

Claim 4

The method of claim 1 wherein the partial erasure of the data tracks is effected before the rewriting on the data tracks.

Claim 5

The method of claim 1 wherein the rewriting on the data tracks is effected before the partial erasure of the data tracks.

Claim 8

The method of claim 5 wherein the read/write head of the head assembly is maintained in operation in an erase mode along with the pair of erase heads during the partial erasure of the data tracks.

Claim 9

The method of claim 5 wherein the partial erasure of the data tracks including the home track is effected before the rewriting on the data tracks.

Claim 10

The method of claim 5 wherein the rewriting on the data tracks is effected before the partial erasure of the data tracks including the home track.

Claim 11

Apparatus for data transfer with a magnetic disk, which apparatus is capable of rewriting on a magnetic disk on which data has been written on a plurality of concentric data tracks arranged with a prescribed pitch P1, each data track having a width W1, the apparatus comprising: (a) disk drive means for imparting rotation to the magnetic disk; (b) a magnetic head assembly having a read/write head and a pair of erase heads disposed on both sides of the read/write head, the read/write head having a read/write gap capable of providing a track width W2 which is in the range of 0.4 W1 to 0.6 W1, each erase head having an erase gap capable of providing an erase width E2 which is in the range of (W1-W2)/2 to (P1/2-W2); (c) head control means for setting the read/write head and erase heads of the head assembly in and out of operation; (d) head positioning means including a head positioning motor for incrementally transporting the head assembly across the data tracks on the magnetic disk; (e) first circuit means connected to the head positioning motor for causing the head positioning means to position the head assembly on any selected one of the data tracks on the magnetic disk; (f) second circuit means associated with the first circuit means for causing the head positioning means to successively position the head assembly intermediate the data tracks on the magnetic disk; (g) whereby the apparatus can thoroughly erase the existing data tracks on the magnetic disk and rewrite thereon by successively positioning the head assembly intermediate the data tracks for erasing a pair of opposite edge portions of each data track, with at least the pair of erase heads of the head assembly held in operation, and by successively positioning the head assembly on the data tracks for rewriting thereon, with the pair of erase heads of the head assembly maintained in operation during the rewriting.

Claim 12

Apparatus for data transfer with a magnetic disk, which apparatus is capable of rewriting on a magnetic disk on which data has been written on a plurality of concentric data tracks arranged with a prescribed pitch P1, each data track having a width W1, the apparatus comprising: (a) disk drive means for imparting rotation to the magnetic disk; (b) a magnetic head assembly having a read/write head and a pair of erase heads disposed on both sides of the read/write head, the read/write head having a read/write gap capable of providing a track width W2 which is in the range of 0.4 W1 to 0.6 W1, each erase head having an erase gap capable of providing an erase width E2 which is in the range of (W1-W2)/2 to (P1/2-W2); (c) head control means for setting the read/write head and erase heads of the head assembly in and out of operation; (d) head positioning means including a head positioning motor for incrementally transporting the head assembly across the data tracks on the magnetic disk; (e) first circuit means connected to the head positioning motor for causing the head positioning means to position the head assembly on any selected one of the data tracks on the magnetic disk; (f) second circuit means associated with the first circuit means for causing the head positioning means to successively position the head assembly intermediate the data tracks on the magnetic disk; (g) whereby the apparatus can thoroughly erase the existing data tracks on the magnetic disk and rewrite thereon by successively positioning the head assembly intermediate the data tracks for erasing a pair of opposite edge portions of each data track, with at least the pair of erase heads of the head assembly held in operation, and by successively positioning the head assembly on the data tracks for rewriting thereon, with the pair of erase heads of the head assembly maintained in operation during the rewriting.

Claim 13

The apparatus of claim 9 wherein the track width W2 is about 0.5 W1.

Claim 14

The apparatus of claim 9 wherein the track width W1 is about 300 micrometers, and the track width W2 is about 155 micrometers.

Claim 15

Apparatus for data transfer with a magnetic disk, which apparatus is capable of rewriting on a magnetic disk on which data has been written on a plurality of concentric data tracks each having a width W1, the data tracks being arranged with a prescribed pitch P1 in a data storage region of the magnetic disk and including a home track at a boundary between the data storage region and a non-data-storage region of the magnetic disk, the apparatus comprising: (a) disk drive means for imparting rotation to the magnetic disk; (b) a magnetic head assembly having a read/write head and a pair of erase heads disposed on both sides of the read/write head, the read/write head having a read/write gap capable of providing a track width W2 which is in the range of 0.4 W1 to 0.6 W1, each erase head having an erase gap capable of providing an erase width E2 which is in the range of (W1-W2)/2 to (P1/2-W2); (c) head control means for setting the read/write head and erase heads of the head assembly in and out of operation; (d) head positioning means including a head positioning motor for incrementally transporting the head assembly across the data tracks on the magnetic disk; (e) first circuit means connected to the head positioning motor for causing the head positioning means to position the head assembly on any selected one of the data tracks on the magnetic disk; (f) sensor means for producing a home track signal indicative of the fact that the head assembly is positioned on the home track on the magnetic disk; (g) second circuit means associated with the first circuit means for causing the head positioning means to position the head assembly at a distance of half the pitch P1 in either direction from each data track on the magnetic disk; (h) "overrun" signal input means for inputting an "overrun" signal directing the positioning of the head assembly on a notional track which is located in the non-data storage region of the magnetic disk and which is distanced half the pitch P1 from the home track; (i) third circuit means connected to both the sensor means and the "overrun" signal input means for producing a pseudo-home-track signal when the head assembly is positioned on the notional track on the magnetic disk; and (j) "double track density" signal input means connected to the second circuit means for delivering thereto a "double track density" signal directing the positioning of the head assembly at a distance of half the pitch P1 in either direction from each data track after the head assembly has been positioned on the notional track.

Claim 16

Apparatus for data transfer with a magnetic disk, which apparatus is capable of rewriting on a magnetic disk on which data has been written on a plurality of concentric data tracks each having a width W1, the data tracks being arranged with a prescribed pitch P1 in a data storage region of the magnetic disk and including a home track at a boundary between the data storage region and a non-data-storage region of the magnetic disk, the apparatus comprising: (a) disk drive means for imparting rotation to the magnetic disk; (b) a magnetic head assembly having a read/write head and a pair of erase heads disposed on both sides of the read/write head, the read/write head having a read/write gap capable of providing a track width W2 which is in the range of 0.4 W1 to 0.6 W1, each erase head having an erase gap capable of providing an erase width E2 which is in the range of (W1-W2)/2 to (P1/2-W2); (c) head control means for setting the read/write head and erase heads of the head assembly in and out of operation; (d) head positioning means including a head positioning motor for incrementally transporting the head assembly across the data tracks on the magnetic disk; (e) first circuit means connected to the head positioning motor for causing the head positioning means to position the head assembly on any selected one of the data tracks on the magnetic disk; (f) sensor means for producing a home track signal indicative of the fact that the head assembly is positioned on the home track on the magnetic disk; (g) second circuit means associated with the first circuit means for causing the head positioning means to position the head assembly at a distance of half the pitch P1 in either direction from each data track on the magnetic disk; (h) "overrun" signal input means for inputting an "overrun" signal directing the positioning of the head assembly on a notional track which is located in the non-data storage region of the magnetic disk and which is distanced half the pitch P1 from the home track; (i) third circuit means connected to both the sensor means and the "overrun" signal input means for producing a pseudo-home-track signal when the head assembly is positioned on the notional track on the magnetic disk; and (j) "double track density" signal input means connected to the second circuit means for delivering thereto a "double track density" signal directing the positioning of the head assembly at a distance of half the pitch P1 in either direction from each data track after the head assembly has been positioned on the notional track.