JP2009140560A - Storage device and displacement control circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve following accuracy by suppressing vibration of a recording medium caused in the direction of rotary shaft of the recording medium, reducing disturbance of air stream generated around the recording medium, and facilitating the following of a magnetic head for a recording track on a storage medium. <P>SOLUTION: The storage device has a storage medium 3, a spindle motor 2 for rotation-driving the storage medium, and a head 4-1 for recording and reproducing a signal for the storage medium. The device also has a shroud 6 for suppressing displacement of the rotary shaft direction of the rotatry storage medium, the shroud has an opposite plane opposing to the storage medium in a contactless manner, and the opposite plane has a vibration generator 6-2 driven in the direction of rotary shaft direction in accordance with an external control signal. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a storage device including a rotary storage medium that records and reproduces information.

  In recent years, a high transfer rate and a large capacity have been demanded as performance required for a storage device, particularly a magnetic recording device including a rotary magnetic recording medium. As the performance of computers increases, the required performance tends to improve.

  A configuration example of a conventional magnetic disk device is shown in FIG. The magnetic disk device 50 includes a magnetic disk medium 52, a magnetic head 53 that performs recording and reproduction, a head arm 54 that supports the magnetic head 53, and a VCM 55 that is a positioning mechanism for the magnetic head 53. Yes. A preamplifier 56 for the magnetic head 53 is mounted on the magnetic head 53 or the head arm 54. On a circuit board (not shown), a read channel (RDC) 57 for controlling a recording / reproducing signal, a signal and a command from a host such as an external PC as a magnetic disk device are received, and the operation of the magnetic disk device is controlled. A power controller 59 for driving the VCM 55 is mounted according to servo signals from the HD controller (HDC) 58 and HDC 58.

  The recording / reproducing operation is as follows. The preamplifier 56 amplifies a weak reproduction signal from the magnetic head of the magnetic head 53 and sends it to the RDC 57. In the RDC 57, it is taken out as servo signals and recording / reproducing signals through various filters. A signal recorded on the magnetic disk medium 52 has a servo signal area at the head, followed by a data signal area.

  When positioning the magnetic head 53, the servo signal is read from the reproduction signal and processed. The servo signal demodulated in the RDC 57 becomes a positioning control signal in the HDC 58, and a signal for controlling the VCM 55 is sent to the power controller 59. The power controller 59 converts the drive signal into a current and operates the VCM 55.

  As the recording density increases, there is a tendency to narrow the track to narrow the interval between data tracks to be recorded. In addition, in order to improve the performance as a storage device, the data transfer time tends to be shortened. In order to realize this, it is effective to increase the rotational speed of the storage medium. However, for example, if the rotational speed is increased in a state where magnetic recording media are stacked, vibration from the rotation mechanism of the magnetic recording medium and turbulence of the air flow in the vicinity of the magnetic recording medium increase, and the rotation axis of the magnetic recording medium is increased. The magnetic head is easily oscillated in a parallel direction (normal direction of the magnetic recording medium surface). This vibration causes an increase in the amount of positional deviation of the magnetic head with respect to the track, and the above-described difficulty in positioning accuracy due to the narrowing of the track is superimposed, which causes a decrease in recording / reproducing performance.

As a technique for coping with the vibration of the magnetic recording medium, for example, in Patent Document 1, the displacement of the magnetic recording medium surface in the direction of the rotation axis is detected, and the position change amount of the magnetic head according to this is given to correct the position of the magnetic head. It is carried out.
JP 2006-107708 A

  The frequency band that the head follows corresponding to the displacement in the rotation axis direction of the storage medium is limited, and generally responds to a frequency of about several kHz. In addition, the suspension holding the head is also vibrated by the vibration in the direction of the rotation axis of the storage medium, which causes mechanical high-order vibrations. For this reason, it is not possible to reduce the influence of the higher-order vibration inherent in the suspension only by detecting the vibration of the storage medium and performing the feedforward control.

  In view of the above, the present invention solves the above problems, suppresses the vibration of the storage medium that occurs in the direction of the rotation axis of the storage medium, reduces the turbulence of the air flow generated around the storage medium, and records on the storage medium. The purpose is to facilitate the tracking of the head to the track and to improve the tracking accuracy.

  In order to solve the above problems, the present invention comprises the following storage device.

  In order to suppress the turbulence of the air flow around the storage medium, for example, a rigid shroud fixed to the base to which the spindle motor, VCM, etc. of the storage apparatus is attached is attached to the rotating storage medium in a non-contact manner. ing. A vibration generator is disposed on the surface of the shroud facing the storage medium surface.

  Here, a shape changing portion having a shape changing element instead of the vibration generator may be arranged on or near the surface of the shroud facing the storage medium surface.

  For example, a piezoelectric element is used as the vibration generating element of the vibration generator or the shape displacement element of the shape changing portion. There are two types of piezoelectric elements used here, and the piezoelectric element used as the vibration generating element is a displacement of the storage medium that occurs in the direction of the rotation axis of the storage medium (hereinafter, in the present invention, simply the storage medium This is a piezoelectric element that generates a displacement) and is a component of a vibration generator. The piezoelectric element used as the shape changing element of the shape changing portion is a shape changing element using a bimorph type element in which two types of piezoelectric elements having different displacements with respect to the applied voltage are bonded to the surface of the storage medium. On the other hand, a shape changing portion that generates a projecting displacement is formed.

  In order to control the operation of the piezoelectric element, a servo signal read from the storage medium by the head is used. Using a displacement signal indicating the displacement amount of the head from the track included in the servo signal, control is performed in a direction in which the displacement amount decreases. Based on the displacement signal obtained from the servo signal, the piezoelectric element is energized through a driver circuit that drives the piezoelectric element.

  On the other hand, in order to detect the displacement of the storage medium, for example, a medium displacement detector is arranged on the surface of the shroud facing the storage medium. As the displacement amount detection element, a capacitance element is used. For example, the storage medium area is covered by the shroud. The storage medium area is one at the center of the storage medium. Alternatively, the storage medium is disposed at two locations on the storage medium entrance side where the rotating storage medium rotates and the storage medium surface away from the shroud. In the case where they are arranged at the two locations, it is possible to observe the displacement before and after the control. In addition to the normal recording / reproducing signal, a displacement amount detection circuit is added to the storage medium device, and the vibration generator and the shape displacement unit are controlled so that the output from the displacement amount detection circuit is constant.

As a control method, feedforward control is used. The tendency of the displacement of the storage medium over one round of the storage medium is measured in advance at a certain radial position from the center of the storage medium, and this state is stored in the memory in the control circuit of the storage device for learning. I do. By giving a control signal having a phase opposite to the direction of displacement of the storage medium and driving the vibration generating element or the shape change element, vibration in the direction of displacement of the storage medium is suppressed. An optimum medium vibration suppression state can be created by adjusting the phase difference of the control signal.
The invention according to claim 1 of the present invention is a storage device having a storage medium, a spindle motor that rotationally drives the storage medium, and a head that records and reproduces signals on the storage medium, and rotates. The shroud has a shroud that suppresses displacement of the storage medium in the rotation axis direction, and the shroud has a facing surface that faces the storage medium in a non-contact manner with the storage medium, and the facing surface is in response to an external control signal. A storage device having a vibration generator driven in the direction of the rotation axis.

  According to the first aspect of the present invention, the shroud of the present invention is not a shroud having a plane facing the storage medium but having a predetermined gap from the surface of the rotating storage medium, and constitutes a shroud facing the storage medium. A vibration generator is provided on the surface of the rigid holder.

  The surface of the vibration generating element of the vibration generator is positioned in parallel with the surface of the storage medium, and may protrude from the surface of the holder facing the storage medium, may be substantially the same, or may be retracted.

  The shroud of the present invention is provided with a predetermined gap from the surface of the rotating storage medium. Drive that generates a displacement in the opposite phase to the displacement of the storage medium, for example, using the head tracking control signal as an external control signal in the vibration generating element, together with the action of reducing the air turbulence by the flat portion of the shroud facing the surface of the storage medium When the gap between the surface of the vibration generating element and the surface of the storage medium facing this is reduced by passing an electric current, the air pressure between the surfaces increases, and the air pressure causes the storage medium surface to move away from the surface of the vibration generating element. Power works.

  As a result, a force acts on the storage medium close to the surface of the vibration generating element in a direction that reduces displacement due to vibration caused by high-speed rotation or air turbulence. That is, by attaching the shroud of the present invention to a part of the outer periphery of the storage medium, it serves to suppress the displacement of the corresponding outer periphery of the storage medium that rotates relative to the fixedly attached shroud. When one end of the outer peripheral portion of the rotating storage medium is suppressed from displacement due to vibration, displacement due to vibration of the fan-shaped region of the storage medium surrounded by the outer peripheral portion and the rotation center of the storage medium is suppressed.

  Therefore, by using a storage device having a structure in which the head is floated on the fan-shaped region, the head is floated at a position where displacement due to vibration of the storage medium is suppressed, and stable head tracking can be performed.

  Here, the case where the head is positioned by the rotary type positioner with respect to the track in the fan-shaped area is exemplified, but the linear positioner for the track in the area sandwiched by the two fan-shaped areas spaced apart from each other is illustrated. Of course, the present invention can be applied to a storage device having a structure in which the head is positioned.

  Also, when positioning the head with a rotary type positioner, a plurality of shrouds according to the present invention are provided at intervals along the outer periphery of the storage medium, and the head is placed on a track in an area sandwiched between two fan-shaped areas. A floating structure may be used. In addition, the shroud surface facing the storage medium surface may be provided on both sides of the storage medium or may be provided only on one side. Further, the shroud surface facing the storage medium surface is not limited to being provided on the outer peripheral surface of the storage medium, and has a shape extending from the outer peripheral portion to the inner peripheral portion of the storage medium. It doesn't matter.

  According to a second aspect of the present invention, there is provided a storage device having a storage medium, a spindle motor that rotationally drives the storage medium, and a head that records and reproduces signals on the storage medium, and rotates. The shroud has a shroud that suppresses displacement of the storage medium in the rotation axis direction, and the shroud has a facing surface that faces the storage medium in a non-contact manner with the storage medium, and the facing surface is in response to an external control signal. The storage device includes a shape changing unit that can change a distance from the storage medium.

  According to the second aspect of the present invention, the shroud of the present invention is not a shroud having a plane facing the storage medium but having a predetermined gap from the surface of the rotating storage medium, and a rigidity constituting the shroud facing the storage medium. A shape changing portion is provided on the surface of the holder having

  For example, the piezoelectric element used as the shape changing element of the shape changing unit is a bimorph type element in which both ends of two types of piezoelectric elements having different displacements with respect to the applied voltage are bonded to the surface of the storage medium. A shape changing portion that generates a displacement in the protruding direction is formed.

  The surface of the shape change portion is set substantially parallel to the surface of the storage medium when no voltage is applied to the shape change element, and even if it protrudes from the surface of the holder facing the storage medium, It may be the same.

  The shroud of the present invention reduces the air turbulence caused by a plane provided with a predetermined gap from the surface of the rotating storage medium, and, for example, uses a tracking control signal of a magnetic head as an external control signal. When a drive current that causes a displacement opposite in phase to the displacement of the magnetic disk medium flows, when the surface of the shape-changing element protrudes in a chevron shape and the gap on the surface of the magnetic disk medium facing it decreases, the air pressure increases, A force is generated on the surface of the magnetic disk medium in a direction away from the surface of the shape change element by the pressure.

  As a result, a force acts on the magnetic disk medium close to the surface of the shape change element in a direction to reduce displacement due to vibration caused by high-speed rotation or air turbulence. That is, by attaching the shroud of the present invention to a part of the outer periphery of the magnetic disk medium, it functions to suppress the displacement of the corresponding outer peripheral part of the magnetic disk medium that rotates relative to the fixedly mounted shroud. When one end of the outer periphery of the rotating magnetic disk medium is suppressed from displacement due to vibration, displacement due to vibration of the fan-shaped region of the magnetic disk medium surrounded by the outer periphery and the rotation center of the magnetic disk medium is suppressed.

  Therefore, by using the magnetic disk device having a structure in which the magnetic head is floated on the fan-shaped region, the magnetic head can be floated at a position where the displacement due to the vibration of the magnetic disk medium is suppressed, and stable magnetic head tracking can be performed. it can.

  Here, the case where the magnetic head is positioned by the rotary positioner with respect to the track in the fan-shaped area has been exemplified, but the linear movement type with respect to the track in the area sandwiched by the two fan-shaped areas spaced apart from each other. Of course, the present invention can be applied to a magnetic disk apparatus having a structure in which a magnetic head is positioned by a positioner.

  Also, even when the magnetic head is positioned by a rotary positioner, a plurality of shrouds according to the present invention are provided at intervals along the outer periphery of the magnetic disk medium, and a track in an area sandwiched between two fan-shaped areas is provided. The magnetic head may be levitated and seeked. In addition, the shroud surface facing the storage medium surface may be provided on both sides of the storage medium or may be provided only on one side. Further, the shroud surface facing the storage medium surface is not limited to being provided on the outer peripheral surface of the storage medium, and has a shape extending from the outer peripheral portion to the inner peripheral portion of the storage medium. It doesn't matter.

  The invention according to claim 3 of the present invention is the storage device according to claim 1 or 2, wherein a piezoelectric element is used for the vibration generator or the shape changing portion.

  The invention according to claim 4 of the present invention has means for learning and storing the displacement of the surface at a predetermined position in the radial direction of the storage medium. It is.

  According to a fifth aspect of the present invention, the vibration generator or the shape changing unit is fed by the external control signal based on a learning result of the displacement in the rotational axis direction at a predetermined position in the radial direction of the storage medium. 5. The storage device according to claim 4, wherein forward control is performed.

  According to a sixth aspect of the present invention, there is provided a medium displacement detector for detecting a displacement of the storage medium in the rotational axis direction on the facing surface of the shroud. 5. The storage device according to 5.

  According to a seventh aspect of the present invention, there is provided the medium displacement detection means of the shroud having a displacement suppression means and a medium displacement detection means in the rotational axis direction of the storage medium on a facing surface that is not in contact with the rotating storage medium. Receiving a medium displacement signal to be detected, and detecting in advance the displacement in the rotational axis direction over the circumference of the storage medium at a certain radial position from the center of the storage medium by the medium displacement detection means; Displacement in the rotational axis direction of the storage medium by storing in a predetermined memory and learning, and providing a control signal having a phase opposite to the displacement direction of the storage medium to the displacement suppression means It is a displacement control circuit which carries out suppression control by feedforward control.

  The shroud of the present invention reduces the displacement of the storage medium due to the active vibration reduction effect brought about by the vibration generator and the shape changer in addition to the static air turbulence reduction effect. In the region, it is possible to obtain a region with a small displacement that could not be realized conventionally.

  In addition, since the piezoelectric element has a response speed of several tens of kHz, in addition to low-order vibration corresponding to the rotation speed of the storage medium, displacement of the storage medium with respect to high-order vibration can be suppressed. As a result, the displacement of the storage medium surface due to vibration is essentially reduced, and fluctuations applied to the suspension of the head and turbulence of the air flow around the medium can be reduced. Therefore, the vibration of the storage medium and the entire head can be reduced. it can.

  Furthermore, by arranging the medium displacement detector on the surface of the shroud facing the storage medium, it is possible to accurately grasp the vibration state of the storage medium. That is, the storage medium is arranged at two locations, approximately one in the center of the storage medium area covered by the shroud, or on the side where the rotating storage medium enters the shroud and on the side where the storage medium moves away from the shroud. In particular, since it is possible to observe the displacement before and after the control by arranging at two places as described above, the feedforward control can be performed because the phase difference between the displacement signal of the storage medium and the control signal can be strictly controlled. Lead to stabilization.

  Although the magnetic head tries to follow the displacement of the storage medium, the suspension is operated in a twisting direction. In particular, when the head is located on the outer periphery of the storage medium, the operation in the twisting direction becomes intense. For example, when the magnetic head is mounted on the upper surface of a magnetic recording medium positioned in the horizontal direction, the magnetic recording medium moves outward when the magnetic recording medium is displaced upward, and the magnetic recording medium moves when the magnetic recording medium is displaced downward. The magnetic head moves to the inner circumference side of the medium, causing off-track, but by suppressing the displacement of the magnetic recording medium, the positioning accuracy of the magnetic head with respect to the target track is improved and high-speed recording of the high recording density medium is performed. A high-performance storage device that is stable in a state can be provided.

  The details of the present invention will be described below with reference to an example of a magnetic disk device according to an embodiment of the present invention.

  FIG. 1 shows an embodiment of a shroud according to the present invention. FIG. 1 shows a main part of a magnetic disk apparatus according to the present invention. A base 1 that is a substrate having a structure of a magnetic disk device is made of, for example, aluminum die casting, and a spindle motor 2 that rotates a magnetic recording medium 3 is attached to the base 1.

  In the figure, the motor portion of the spindle motor 2 on the opposite side of the base 1 from the magnetic recording medium 3 is not shown. The hub 2-1 holding the magnetic recording medium 3 is directly connected to the rotating shaft of the motor of the spindle motor 2, and the magnetic recording medium 3 is clamped to the hub 2-1 via a spacer 2-2 as necessary. It is fixed by 2-3.

  The magnetic head 4-1 is supported by a suspension 4-2 made of a stainless steel leaf spring, and is positioned at a desired position on the magnetic recording medium 3 by a rotary drive type head positioner 5. The head positioner 5 includes a magnetic circuit 5-1, a rotating shaft 5-2, and a head arm 5-3. A magnetic head 4-1 supported by a suspension 4-2 is attached to the tip of the head arm 5-3. ing.

  Further, the shroud 6 is configured on the basis of a holder 6-1 made of, for example, stainless steel, which is made of a nonmagnetic material and is rigid. The holder 6-1 is fixed to the base 1 and faces the magnetic recording medium 3. The vibration generator 6-2 is attached to each of the two surfaces 1, and has a planar shape with a larger facing area so as to suppress any disturbance of the air flow around the magnetic recording medium 3.

  For this reason, the surface of the vibration generator 6-2 facing the magnetic recording medium 3 may protrude from the two surfaces of the holder 6-1 facing the magnetic recording medium 3 or may be on the same plane. Although it does not matter, a flat shape with a large area is preferable. Further, the distance between the magnetic recording medium 3 and the surface of the vibration generator 6-2 is, for example, 0.1 to 0.3 mm as a range that does not contact the medium when vibration is generated.

  Here, the cross-sectional view of the magnetic head is omitted from the A-A ′ cross-sectional view of FIG. Further, details of the inside of the vibration generator 6-2, illustration of electric wiring for driving, terminals, and the like, and a detailed view of the magnetic head portion are omitted. Further, although the case of one magnetic recording medium 3 is illustrated, there may be a plurality of sheets. In the case of a plurality of sheets, the shroud 6 is provided with a vibration generator for the surface of each magnetic recording medium. Yes. The vibration generator 6-2 is not necessarily arranged on both sides of the magnetic recording medium 3, and may be arranged on one side.

  The shape of the vibration generator 6-2 and the position where the vibration generator 6-2 is installed are, for example, in the shape shown in the figure, installed on a part of the outer periphery of the magnetic recording medium 3, not in contact with the surface of the magnetic recording medium 3, and the magnetic head 4 It is preferable that the sector where -1 seeks the surface of the magnetic recording medium 3 is covered by a fan-shaped region formed by the substantial center of the magnetic recording medium 3 and the vibration generator 6-2.

The magnetic recording medium 3 of this embodiment is a bit patterned recording medium, which is produced by processing a magnetic recording medium for perpendicular recording by a process such as etching. The width of each recording bit is several tens of nm in the circumferential direction (track direction) and radial direction of the magnetic recording medium, and the height is several nm. In order to stabilize the flying characteristics of the magnetic head 4-1, the gap between the recording bits is filled with a nonmagnetic material, and the medium surface is smoothed by CMP polishing. Here, as the nonmagnetic material, a substance having a magnetic permeability different from that of the recording layer material, for example, silicon dioxide (SiO ₂ ) is used.

  Although the bit patterned recording medium is illustrated as the magnetic recording medium 3 of the present embodiment, it may be a perpendicular storage or an in-plane storage medium formed by a sputtering method.

  FIG. 2 shows another embodiment of a shroud according to the present invention. The difference from FIG. 1 is that medium displacement detectors 6-3A and 6-3B are arranged on both sides of the vibration generator 6-2 in FIG. The opposed surfaces of the medium displacement detectors 6-3A and 6-3B to the magnetic recording medium 3 are preferably in the same plane as the vibration generator 6-2, and the surfaces of the medium displacement detectors 6-3A and 6-3B The amount of displacement from the surface of the magnetic recording medium 3 with reference to is measured by capacitance. The distance between the facing surfaces of the medium displacement detectors 6-3A and 6-3B and the magnetic recording medium 3 is set to 0.1 to 0.3 mm. This figure shows an example in which the rotating magnetic recording medium 3 is arranged at two locations on the entrance side of the shroud 6 and on the side where the magnetic recording medium 3 is away from the shroud 6.

  Here, illustration of electrical wiring, terminals, and the like necessary for the operation of the vibration generator 6-2 and the medium displacement detectors 6-3A and 6-3B is omitted.

  FIG. 3 is an explanatory diagram of a shape changing portion according to the present invention. Instead of the vibration generator 6-2 shown in FIGS. 1 and 2, an example is shown in which the shape changing portion 30-2 is attached to the facing surface of the magnetic recording medium 3 of the holder 30-1 with, for example, an adhesive. .

  FIG. 3A corresponds to the A-A ′ sectional view shown in FIGS. 1 and 2.

  Here, the shape changing portion 30-2 uses a bimorph type piezoelectric element. For example, the inner piece 30-2A and the inner piece 30-3A are contracted in the horizontal direction in the figure by applying a voltage, and the outer piece 30- 2B and the outer piece 30-3B are combined so as to extend in the left-right direction in the figure.

  As shown in the figure, the inner piece and the outer piece are joined at both ends or facing each other, and when a voltage is applied, the outer piece surface protrudes like a bow toward the surface of the magnetic recording medium 3 as a result. ing. Here, illustration of electrical wiring, terminals, and the like necessary for the operation of the shape changing unit 30-2 is omitted.

  The gap between the surface of the medium displacement detectors 6-3A and 6-3B and the surface of the magnetic recording medium 3 is set to about 0.2 mm, and the displacement due to vibration or the like of the surface of the magnetic recording medium 3 occurs. For example, a displacement amount of ± 0.1 mm is obtained.

  As the operation, for example, the gap on the entry side to the shroud 30 with respect to the rotation direction 3-2 of the magnetic recording medium 3 is set to about 0.4 mm, and the gap at the bending point of the outer pieces 30-2B and 30-3B is minimized. The arrangement is 0.1 mm. When the magnetic recording medium 3 is displaced by vibration or the like in the upper direction of the figure, the gap with the surface of the magnetic recording medium 3 is reduced so that the outer piece 30-2B projects like a bow as shown in FIG. Displace in the direction.

  At this time, since the gap at the bending point of the outer piece 30-2B becomes narrower than the pressure on the entry side to the shroud, the air pressure at the bending point of the outer piece 30-2B increases, and as a result, A force acts in the direction of pushing down the magnetic recording medium 3 at the bending point of the outer piece 30-2B.

Conversely, as shown in FIG. 3C, when the magnetic recording medium 3 is displaced downward in the figure by vibration or the like, a bending point is generated in the lower outer piece 30-3B, and the gap with the magnetic recording medium 3 is increased. Is controlled so as to be narrowed to generate a pressure for suppressing the displacement of the magnetic recording medium 3. The series of operations is an operation according to the law of conservation of momentum in fluid mechanics, and pressure energy (p ₁ * A ₁ ) + viscous force (ρ ₁ * A ₁ *) near the entrance where the rotating magnetic recording medium 3 enters the shroud. V ₁ ² ) + shearing force (F ₁ ) is the pressure energy (p ₂ * A ₂ ) + viscosity (ρ ₂ * A ₂ * V ₂ ² ) at the bending point of the outer piece 30-2B or the outer piece 30-3B. ) + Equal to shear force (F ₂ ). That is,
p ₁ * A ₁ + ρ ₁ * A ₁ * V ₁ ² + F ₁ = p ₂ * A ₂ + ρ ₂ * A ₂ * V ₂ ² + F ₂

  Here, the suffixes 1 and 2 are the outer piece 30-2B or the outer piece where the former is near the entrance where the rotating magnetic recording medium 3 enters the shroud, and the latter is the smallest gap with the rotating magnetic recording medium 3. The position of the bending point of 30-3B is shown.

p ₁ and p ₂ are pressures, A ₁ and A ₂ are cross-sectional areas of rectangular gaps formed by the outer pieces 30-2B or 30-3B facing the magnetic recording medium 3, ρ ₁ and ρ ₂ are air densities, V ₁ and V ₂ indicate the velocity of air passing through the rectangular gap.

  During this operation, if the density of air hardly changes, and if the rotation speed of the magnetic recording medium 3 is constant, the gap changes due to the displacement of the shape change portion, the cross-sectional area decreases, and the pressure increases relatively. I understand that

  FIG. 4 shows a configuration example of a displacement control system for a magnetic recording medium according to the present invention. In the figure, a circuit for driving the vibration generator 6-2, controlling the change in displacement of the magnetic recording medium 3 in the vicinity of the vibration generator 6-2, and detecting a signal from the medium displacement detector 6-3 is shown. . The medium displacement signal obtained from the medium displacement detector 6-3 using the capacitance displacement is amplified by the displacement signal amplifier circuit 41 and sent to the control circuit. Here, through the filter circuit 42, noise is removed, and an optimal signal for determining the displacement of the magnetic recording medium 3 is extracted through filtering with HPF and LPF.

  Thereafter, A / D conversion is performed in the A / D converter 43, the digital signal is sent to the control signal detection FF control circuit, and the drive signal is sent from the ultrasonic vibration drive circuit to the vibration generator 6-2.

  In this way, the vibration generator 6-2 is driven so as to suppress the displacement of the magnetic recording medium 3 based on the medium displacement signal from the medium displacement detector 6-3.

  Further, displacement information for one round of a predetermined track of the magnetic recording medium 3 is stored in the learning function memory area 44 inside the magnetic disk device, and FF control is performed based on this stored state. By disposing the medium displacement detector 6-3 for detecting the amount of displacement of the magnetic recording medium 3 at two locations, before and after applying air vibration to the magnetic recording medium 3 by the vibration generator 6-2, It is possible to compare the effect and stability of the control and improve the stability of the operation.

  The air vibration generated by the vibration generator 6-2 has a frequency corresponding to the natural vibration generated according to the rotational speed of the magnetic recording medium 3. For example, in the case of the magnetic recording medium 3 rotating at 5400 rpm, a pulse-like vibration having a period of 90 to 100 Hz is given. Further, if there is a higher order vibration, a vibration having a higher frequency may be given. By observing changes before and after applying vibration, the optimum control state can be obtained.

  In the example of FIG. 4, the operation of the vibration generator 6-2 is controlled based on the signal from the medium displacement detector 6-3. However, the control can also be performed using a tracking servo signal from the magnetic head. Here, FIG. 1 shows an example in which the medium displacement detector is not provided. In this case, control is performed using a tracking servo signal from the magnetic head, and the control is not synchronized with the rotational vibration component. Control may be performed using the reduction of the displacement signal component (NRPE) as a guideline.

  It can also be seen that increasing the rotational speed of the magnetic recording medium to increase the transfer speed increases the amount of pressure fluctuation that controls the displacement of the magnetic recording medium, and the vibration reduction effect can be obtained more easily. Also, the control operations of the shape changing units 30-2 and 30-3 in FIG. 3 are the same as the contents shown in FIG. In response to the signal from the medium displacement detector 6-3, the shape changing units 30-2 and 30-3 are controlled to perform an operation of suppressing the displacement of the magnetic recording medium.

  As described above, according to the present invention, in a high recording density medium, a decrease in track positioning accuracy due to vibration of the storage medium can be prevented, and stable servo control can be performed.

  It is possible to displace the storage medium by creating a pressure change by generating air vibration with a vibration generator and adjusting the gap with the storage medium using the shape change element in the shape change part. The effect of the shroud according to the present invention can be actively controlled.

  In order to control this, a medium displacement detector using capacitance is arranged in the shroud to detect the displacement of the storage medium. The obtained control signal is extracted as an effective displacement signal through a displacement signal amplifier circuit and a filter circuit, and feedforward control is performed to obtain a drive signal for a vibration generator and a shape change element used for the shape change portion. . A stable control can be performed by having a circuit for storing a displacement signal for a predetermined track of the storage medium and learning its operation.

  The above-described technique for controlling the displacement of the storage medium to improve the track positioning accuracy is applicable not only to bit patterned recording media but also to discrete track recording media and ordinary continuous film recording media. Can be applied.

  Further, the present invention can be applied to a storage device using an optical signal or a magneto-optical signal, without needing to be exemplified.

  As described above, it is possible to provide a storage device that greatly contributes to the improvement of the device performance and has a good recording / reproduction signal at a high recording density.

Here, the detailed features of the present invention will be described again with reference to FIGS.
(Appendix 1)
A storage device that includes a storage medium, a spindle motor that rotationally drives the storage medium, and a head that records and reproduces signals to and from the storage medium, and suppresses displacement of the rotating storage medium in the rotation axis direction. A shroud, the shroud having a facing surface that is in non-contact with the storage medium and faces the storage medium, and a vibration generator that is driven in the direction of the rotation axis in response to an external control signal is provided on the facing surface. A storage device comprising:
(Appendix 2)
A storage device that includes a storage medium, a spindle motor that rotationally drives the storage medium, and a head that records and reproduces signals to and from the storage medium, and suppresses displacement of the rotating storage medium in the rotation axis direction. A shape change in which the shroud has a facing surface that faces the storage medium in a non-contact manner with the storage medium, and the facing surface is variable in accordance with an external control signal. A storage device comprising: a storage unit.
(Appendix 3)
The storage device according to appendix 1 or appendix 2, wherein a piezoelectric element is used for the vibration generator or the shape changing portion.
(Appendix 4)
The storage device according to any one of supplementary notes 1 to 3, further comprising means for learning and storing a displacement of a surface at a predetermined position in a radial direction of the storage medium.
(Appendix 5)
The supplementary note 4 wherein feedforward control of the vibration generator or the shape changing unit is performed by the external control signal based on a learning result of the displacement in the rotation axis direction at a predetermined position in the radial direction of the storage medium. Storage device.
(Appendix 6)
6. The storage device according to appendix 1 to appendix 5, wherein a medium displacement detector for detecting a displacement of the storage medium in the rotation axis direction is provided on the facing surface of the shroud.
(Appendix 7)
The storage device according to appendix 6, wherein the vibration generator or the shape changing unit is controlled using a signal from the medium displacement detector.
(Appendix 8)
Receiving a medium displacement signal detected from the medium displacement detection means of the shroud having a displacement suppression means in the rotational axis direction of the storage medium and a medium displacement detection means on a facing surface that is not in contact with the rotating storage medium; Detecting the displacement in the rotation axis direction over one rotation of the storage medium at a certain radial position from the center of the storage medium by the medium displacement detection means, storing the displacement in a predetermined memory, and learning. A displacement control circuit that suppresses and controls the displacement of the storage medium in the rotation axis direction by feedforward control by providing a control signal having a phase opposite to the direction of displacement of the storage medium to the displacement suppression means.

An embodiment of a shroud according to the present invention Other embodiments of the shroud according to the present invention Explanatory drawing of the shape change part by this invention An example of the configuration of a displacement control system for a magnetic recording medium according to the present invention Conventional example

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base 2 Spindle motor 3 Magnetic recording medium 4-1, 53 Magnetic head 5 Head positioner 6, 30 Shroud 41 Displacement signal amplifier circuit 42 Filter circuit 43 A / D converter 44 Learning function memory area 45 Control signal detection FF control circuit 46 Ultrasonic vibration drive circuit 50 Magnetic disk device 51 Device housing 52 Magnetic disk medium
54 Head Arm 55 VCM
56 Preamplifier 57 RDC
58 HDC
59 Power Controller

Claims (7)

A storage medium;
A spindle motor that rotationally drives the storage medium;
A storage device having a head for recording and reproducing signals to and from the storage medium,
A shroud for suppressing displacement of the rotating storage medium in the rotation axis direction;
The shroud has a facing surface that faces the storage medium without contacting the storage medium;
The storage device according to claim 1, further comprising a vibration generator that is driven in the direction of the rotation axis in accordance with an external control signal.   A storage device that includes a storage medium, a spindle motor that rotationally drives the storage medium, and a head that records and reproduces signals to and from the storage medium, and suppresses displacement of the rotating storage medium in the rotation axis direction. A shape change in which the shroud has a facing surface that faces the storage medium in a non-contact manner with the storage medium, and the facing surface is variable in accordance with an external control signal. A storage device comprising: a storage unit.   The storage device according to claim 1, wherein a piezoelectric element is used for the vibration generator or the shape changing unit.   4. The storage device according to claim 1, further comprising means for learning and storing a displacement of the surface at a predetermined position in the radial direction of the storage medium.   5. The feedforward control of the vibration generator or the shape changing unit is performed by the external control signal based on a learning result of the displacement in the rotation axis direction at a predetermined position in the radial direction of the storage medium. The storage device described.   6. The storage device according to claim 1, wherein a medium displacement detector that detects a displacement of the storage medium in the rotation axis direction is provided on the facing surface of the shroud. Receiving a medium displacement signal detected from the medium displacement detection means of the shroud having a displacement suppression means and a medium displacement detection means in the rotational axis direction of the storage medium on a surface that is not in contact with the rotating storage medium;
The displacement in the rotation axis direction over one rotation of the storage medium at a certain radial position from the center of the storage medium is detected in advance by the medium displacement detection means, and the displacement is stored in a predetermined memory for learning. Stages,
A displacement control circuit that suppresses and controls the displacement of the storage medium in the rotation axis direction by feedforward control by providing a control signal having a phase opposite to the direction of displacement of the storage medium to the displacement suppression means.

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