EP0306715A1 — Control system of magnetic head positioners of a …

Claim 1

Independent Claim 221 words

In a magnetic disk storage apparatus having a magnetic disk assembly (10) including a plurality of magnetic disks (11), a plurality of magnetic head positioners (20a, 20b), each positioner (20a, 20b) being driven by a driving means (18, 50) independently from each other to position a magnetic head (13a, 13b) supported thereby, and a housing (21) enclosing thereinside and securing thereto said magnetic disk assembly (10) and magnetic head positioners (20a, 20b), characterized by said magnetic disk storage apparatus further having a mechanical vibration follow-up system comprising: a sensor means (6) for sensing mechanical vibration of said housing (21) in an access direction and outputting a sense current, said mechanical vibration being caused by start of a seek operation of a first magnetic head positioner (20a) selected from said plurality of magnetic head positioners (20a, 20b); and a signal processing circuit (3, 7, 8, 9) operatively connected to said sensor means (6), receiving said sense current, generating a compensating signal to follow up said mechanical vibration being in proportion to said sense current, and transferring said compensating signal to a driving means for driving a second magnetic head positioner (20b) which is not selected for said seek operation, thereby, there is compensated off-track of a magnetic head (13b) supported by said second magnetic head positioner (20b), caused by said mechanical vibration.

Claim 2

Dependent Claim 221 words

In a magnetic disk storage apparatus having a magnetic disk assembly (10) including a plurality of magnetic disks (11), a plurality of magnetic head positioners (20a, 20b), each positioner (20a, 20b) being driven by a driving means (18, 50) independently from each other to position a magnetic head (13a, 13b) supported thereby, and a housing (21) enclosing thereinside and securing thereto said magnetic disk assembly (10) and magnetic head positioners (20a, 20b), characterized by said magnetic disk storage apparatus further having a mechanical vibration follow-up system comprising: a sensor means (6) for sensing mechanical vibration of said housing (21) in an access direction and outputting a sense current, said mechanical vibration being caused by start of a seek operation of a first magnetic head positioner (20a) selected from said plurality of magnetic head positioners (20a, 20b); and a signal processing circuit (3, 7, 8, 9) operatively connected to said sensor means (6), receiving said sense current, generating a compensating signal to follow up said mechanical vibration being in proportion to said sense current, and transferring said compensating signal to a driving means for driving a second magnetic head positioner (20b) which is not selected for said seek operation, thereby, there is compensated off-track of a magnetic head (13b) supported by said second magnetic head positioner (20b), caused by said mechanical vibration.

Claim 3

Dependent Claim 27 words

A magnetic disk storage apparatus of claim 1, characterized in that said sensor means comprises an acceleration sensor (6) including a piezoelectric accelerometer or a displacement sensor.

Claim 4

Dependent Claim 26 words

A magnetic disk storage apparatus of claim 1 or 2, characterized in that said sensor means (6) is secured to a surface of said housing (21).

Claim 5

Dependent Claim 60 words

A magnetic disk storage apparatus of any one of claims 1 to 3, characterized in that said plurality of magnetic head positioners (20a, 20b) are of linear type having linear access movement, and stacked vertically one above another, and the sense axis of said sensor means (6) coincides with the direction of said linear access movement seen in plan view.

Claim 6

Dependent Claim 77 words

A magnetic disk storage apparatus of any one of claims 1 to 3, characterized in that said plurality of magnetic head positioners (20a, 20b) are of linear type having a linear access movement and disposed horizontally on a plane in a centripetal, symmetrical arrangement with respect to a symmetry axis (Y-Y), and the sense axis of said sensor means (6) coincides with the said symmetry axis (Y-Y) of the arrangement of said magnetic head positioners (20a, 20b).

Claim 7

Dependent Claim 60 words

A magnetic disk storage apparatus of any one of claims 1 to 5, characterized in that said magnetic positioners (20a, 20b) are secured to said housing (21) through suspending means (132, 133) comprising a plurality of spring members (133) and a plurality of damping members (132) causing a low mechanical vibration resonant frequency of said magnetic head positioners (20a, 20b).

Claim 8

Dependent Claim 164 words

A magnetic disk storage apparatus of any one of claims 1 to 6, characterized in that said signal processing circuit comprises: a mechanical vibration follow-up circuit (7) operatively connected to said sensor means (6), receiving said sense current and generating said compensating signal being in proportion to said sense current; and a plurality of adders (8a, 8b) each of which is operatively connected to said mechanical vibration follow-up circuit (7), a positioning controller (3a, 3b) for generating a position error signal, and said driving means (18a, 18b, 50a, 50b) of each magnetic head positioner (20a, 20b), said adder (8a, 8b) adding said compensation signal at least to said position error signal to form a composed signal for driving said driving means (18a, 18b, 50a, 50b), thereby, coil current of a coil of a motor contained in said driving means (18b, 50b) of said relevant second magnetic head positioner (20b) is compensated such that the effect of said mechanical vibration causing said off-track is cancelled.

Claim 9

Dependent Claim 60 words

A magnetic disk storage apparatus of claim 7, characterized in that said signal processing circuit further comprises a plurality of switches (5a, 5b) each of which is disposed between said mechanical vibration follow-up circuit (7) and each of said adders (8a, 8b), and controlled by a controller (4a, 4b) which is disposed to control each of said positioners (20a, 20b).

Claim 10

Dependent Claim 67 words

A magnetic disk storage apparatus of any one of claims 2 to 8, characterized in that said compensating signal is provided by i comp given by the following formula: i comp = m α/Bl where m: mass of the moving position of said magnetic head positioner (20a, 20b) α: acceleration detected basing on said sense signal Bl: positioner force constant of said magnetic head positioner (20a, 20b).

Claim 11

Dependent Claim 96 words

A magnetic disk storage apparatus of any one of claims 7 to 9, characterized in that said mechanical vibration follow-up circuit (7) comprises: a high-pass filter (70) operatively connected to said sensor means (6) for cutting direct current component of said sense current; a low-pass filter (71) operatively connected to said high-pass filter (70), for filtering low frequency component of said sense current outputted from said sensor means (6); and a gain controller (72) operatively connected to said low-pass filter (71), for controlling the gain level of said sense signal filtered by said low-pass filter (71).

Claim 12

Dependent Claim 34 words

A magnetic disk storage apparatus of claim 10, characterized in that said low-pass filter (71) has a low phase shift below (10) degrees and a high gain level in the specified low frequency range.

Claim 13

Dependent Claim 36 words

A magnetic disk storage apparatus of any one of claims 6 to 11, characterized in that said mechanical vibration resonant frequency of said magnetic head positioners (20a, 20b) is included within said/a predetermined low frequency range.

Claim 14

Dependent Claim 74 words

A magnetic disk storage apparatus of any one of claims 1 to 12, characterized in that said plurality of magnetic head positioners (20a, 20b) are of rotary type being rotatable around a center, said magnetic head (13a, 13b) supported said magnetic head positioner (20a, 20b) is transferred along the surface of one of said magnetic disks (11) following an arc orbit having successively changing access directions which is represented by an average access direction.

Claim 15

Dependent Claim 73 words

A magnetic disk storage apparatus of claim 13, characterized in that said compensating signal is provided by a current i com given given in the following formula: i com = KJα/Blr.l where Blr: torque constant of said magnetic head positioner (20a, 20b) l: rotating radius of said magnetic head (20a, 20b) α: acceleration detected basing on said sense signal J: rotation inertia momentum of said magnetic head positioner (20a, 20b) K: a constant.

Claim 16

Dependent Claim 187 words

In a magnetic disk storage apparatus having a magnetic disk assembly (10) including a plurality of magnetic disks (11), a magnetic head positioner (20) which is driven by a driving means (18, 50) to position a magnetic head (13) supported thereby, and a housing (21) enclosing thereinside and securing thereto said magnetic disk assembly and magnetic head positioner (20), characterized by said magnetic disk storage apparatus further having a mechanical vibration follow-up system comprising: a sensor means (6) for sensing mechanical vibration of said housing (21) in an access direction and outputting a sense current, said mechanical vibration being caused by a force exerted to said magnetic disk storage apparatus; and a signal processing circuit (3, 7, 8, 9) operatively connected to said sensor means (6), receiving said sense current, generating a compensating signal to follow up said mechanical vibration being in proportion to said sense current, and transferring said compensating signal to a driving means (18, 50) for driving said magnetic head positioner (20), thereby, there is compensated off-track of a magnetic head (13) supported by said magnetic head positioner (20), caused by said mechanical vibration.

Claim 17

Dependent Claim 187 words

In a magnetic disk storage apparatus having a magnetic disk assembly (10) including a plurality of magnetic disks (11), a magnetic head positioner (20) which is driven by a driving means (18, 50) to position a magnetic head (13) supported thereby, and a housing (21) enclosing thereinside and securing thereto said magnetic disk assembly and magnetic head positioner (20), characterized by said magnetic disk storage apparatus further having a mechanical vibration follow-up system comprising: a sensor means (6) for sensing mechanical vibration of said housing (21) in an access direction and outputting a sense current, said mechanical vibration being caused by a force exerted to said magnetic disk storage apparatus; and a signal processing circuit (3, 7, 8, 9) operatively connected to said sensor means (6), receiving said sense current, generating a compensating signal to follow up said mechanical vibration being in proportion to said sense current, and transferring said compensating signal to a driving means (18, 50) for driving said magnetic head positioner (20), thereby, there is compensated off-track of a magnetic head (13) supported by said magnetic head positioner (20), caused by said mechanical vibration.

Claim 18

Dependent Claim 53 words

A magnetic disk storage apparatus of claim 15, characterized in that said magnetic positioner (20) is secured to said housing (21) through suspended means (132, 133) comprising a plurality of spring members (133) and a plurality of damping members (132), causing a low mechanical vibration resonant frequency of said magnetic head positioner (20).

Claim 19

Dependent Claim 91 words

A magnetic disk storage apparatus of claim 15 or 16, characterized in that said signal processing circuit comprises: a high-pass filter (70) operatively connected to said sensor means (6) for cutting direct current component of said sense current: a low-pass filter (71) operatively connected to said high-pass filter (70), for filtering low frequency component of said sense current outputted from said sensor means (6); and a gain controller (72) operatively connected to said low-pass filter (71), for controlling the gain level of said sense signal filtered by said low-pass filter (71).

Claim 20

Dependent Claim 34 words

A magnetic disk storage apparatus of claim 17, characterized in that said low-pass filter (71) has a low phase shift below 10 degrees and a high gain level in the specified low frequency range.

Control system of magnetic head positioners of a multipositioner magnetic disk storage apparatus

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