JP2006004512A - Reproducing and recording apparatus for information recording disk - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spindle motor which is stabilized in any rotation range and can prevent a shaft from running out. <P>SOLUTION: The reproducing and recording apparatus for an information recording disk drives to rotate a disk by the spindle motor. A flat surface part right-angled to the rotary shaft of the spindle motor and a cylindrical part parallel to the above rotary shaft are formed, and the cylindrical part is fixed to the rotary shaft in one body, and comprises a rotor part provided with driving magnets on an inner peripheral surface of the cylindrical part, a core made of a magnetic material, a coil wound around the core, a cylindrical bearing housing with a bearing arranged inside and the core fitted outside, and a stator part consisting of a base part for supporting the bearing housing, and a magnetized area and a non-magnetized area are formed symmetrical with respect to the straight line of the pickup operation, a biasing magnet is attached to the stator part so as to face the flat surface part. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a mechanism for preventing a shaft runout generated in a spindle motor for rotationally driving an information recording disk and reducing a tracking error.

2. Description of the Related Art In recent years, a disk rotation driving unit of an information recording disk (hereinafter referred to as a disk) such as a CD-ROM or a DVD has various rotations from low speed to high speed in order to stably read information from and write information to the disk. Even in the region, it is required to rotate stably. The disk rotation drive unit is composed of a spindle motor and a turntable attached to its rotation shaft, and this spindle motor also transmits a stable rotation drive force to the turntable in all rotation ranges from low speed to high speed rotation range. Performance is required.
In such a spindle motor, there is a slight clearance (shaft backlash) between the rotating shaft and the bearing portion that supports the rotating shaft, and the rotating shaft moves in the radial direction within this clearance when rotating at high speed. A shaft runout occurs. Due to this shaft runout, there is a problem that the turntable runs out and an information reading error occurs.

As a spindle motor mechanism for solving such a problem, a magnetic body for attracting a driving magnet disposed on a rotor yoke is disposed on a stator base facing a partial angle region of the rotation angle of the rotor portion. There is a mechanism for preventing shaft runout by sucking the rotor in one direction to prevent shaft wobbling (Patent Document 1).
Further, there is a mechanism that eliminates shaft backlash and prevents shaft runout by directly applying a biasing force in one direction to the rotation shaft by a member having elasticity such as a spring material (Patent Document 2).
In addition to this, by partially cutting off the tip of the core on which the magnetic plates are laminated and shifting the magnetic center of the driving magnet and the core, the rotor is biased in one direction to eliminate shaft backlash and thus prevent shaft runout. There is a mechanism. (Patent Document 3)

JP 2001-86717 A Japanese Patent Laid-Open No. 11-136899 Japanese Patent No. 3215019

However, in the case of the shaft shake prevention mechanism described in Patent Document 1, the magnetic force for attracting the rotor yoke depends on the magnetic characteristics of the driving magnet disposed on the rotor.
That is, if the magnetic force of the driving magnet is increased as a means for preventing shaft backlash in order to reliably prevent shaft runout that occurs at high rotation, there is a risk of changing the rotational characteristics of the motor.
Therefore, since the driving magnet used in such a motor is alternately magnetized with N poles and S poles in the rotation direction of the rotor, a cogging torque is generated between the driving magnets and the magnetic material disposed on the stator base. May occur and the rotational characteristics of the motor may be degraded.
Further, in the configuration in which the shaft play is eliminated by applying an urging force to the rotation shaft by the elastic member as in the invention described in the cited document 2, since the rotation shaft and the elastic member are always in pressure contact, noise and friction Deterioration of parts due to the above occurs easily, and there is a problem in the performance and life of the motor.
In the invention described in the cited document 3, since the rotor is biased in one direction by cutting out a part of the core, the magnetic force is weakened in a part of the core, and a reduction in the rotational driving force of the motor becomes a problem.

In order to solve this problem, there is provided a pickup which is a head mechanism for reproducing / recording the disk operating on a straight line perpendicular to the track tangent of the information recording disk, and the disk is driven by a spindle motor. In a reproducing / recording device for an information recording disk to be driven to rotate, a plane part perpendicular to the rotation axis of the spindle motor and a cylindrical part parallel to the rotation axis are formed, and the cylindrical part is fixed integrally with the rotation axis. A rotor portion having a driving magnet disposed on the inner peripheral surface of the cylindrical portion, a core made of a magnetic material, a coil wound around the core, a bearing on the inside, and the core on the outside. A cylindrical bearing housing to be attached and a stator portion comprising a base for supporting the bearing housing, and magnetized in line symmetry with respect to the operation straight line of the pickup Range and non-magnetic areas are formed, may be used the spindle motor in the information recording disk reproducing / recording apparatus having a biasing magnet to face the flat portion is attached to the stator portion.
Specifically, the problem can be solved if the outer shape of the urging magnet is a ring shape centered on the rotation axis, and the spindle motor is magnetized in a range of 180 degrees in the ring shape.

An information recording disk comprising: a pickup which is a head mechanism for reproducing / recording the disk operating on a straight line perpendicular to a track tangent to the information recording disk, and the disk is rotated by a spindle motor. In the reproducing / recording apparatus, a plane portion perpendicular to the rotation axis of the spindle motor and a cylindrical portion parallel to the rotation shaft are formed, and the cylindrical portion is fixed integrally with the rotation shaft, and the inside of the cylindrical portion is A rotor portion on which a driving magnet is arranged on a peripheral surface; a core made of a magnetic material; a coil wound around the core; and a cylindrical bearing housing in which a bearing is provided inside and the core is attached outside. A stator portion that is a base portion that supports the bearing housing, and a magnetized region is formed in line symmetry with respect to an operation straight line of the pickup, Parts may be used spindle motor in the information recording disk reproducing / recording apparatus having a magnet for biasing the opposed to attached to the stator portion.
Specifically, the problem can be solved even with a spindle motor in which the outer shape of the biasing magnet has a 180-degree arc shape centered on the rotation axis and the entire arc-shaped region is magnetized.

If each part of the spindle motor is configured as in the above-described means, the portion of the stator portion facing the flat surface portion of the rotor yoke is attracted by the biasing magnet, and the rotor yoke attached to the rotating shaft is attracted in the direction of the biasing magnet.
As a result, the rotating shaft fixed to the rotor yoke is biased to the bearing portion in the direction of the magnetized region of the biasing magnet, eliminating the clearance (shaft backlash) between the bearing portion and the shaft. It is possible to prevent shaft runout that occurs when the rotor portion rotates.
Further, since the magnetic center of the attracting magnet is on the operation line of the pickup, the direction of the magnetic force acting on the rotor is the same operation line direction, and the direction in which the rotor is biased overlaps the operation line of the pickup.
As a result, the shaft runout generated in the operation direction of the pickup can be minimized, so that the amount of movement of the turntable attached to the shaft due to the shaft runout can be minimized.
Therefore, as a result of the above effects, even in any rotation range from low speed to high speed, the turntable surface runout caused by shaft runout is eliminated and the disk is rotated with high accuracy, and information reading and writing errors (tracking) It is possible to provide an information recording disk reproducing / recording apparatus using a spindle motor that can prevent an error).

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a longitudinal sectional view of a spindle motor showing an embodiment of the present invention.
FIG. 2 shows a state in which the rotor yoke is attracted to the magnetized portion of the biasing magnet.
FIG. 3A shows the positional relationship among the rotating shaft, the bearing, the biasing magnet, and the pickup in the state shown in FIG. 2 as viewed from the axial direction.
FIG. 3 (b) is an enlarged view of the vicinity of the biasing magnet in the diagram shown in FIG. 3 (b).
2 and 3 are exaggerated for easy understanding of the relationship between the motor parts.

The rotor portion R includes a turntable 2, a rotary shaft 3, a rotary table 3, a rotor yoke 1 formed of a magnetic material in a cup shape with a cylindrical portion 1 c that is a cylindrical surface parallel to the top surface 1 b that is a flat portion perpendicular to the rotary shaft 3. The drive magnet 4 is arranged.
The rotating shaft 3 is inserted into a center hole 1 a provided in the top surface 1 b of the rotor yoke 1. The driving magnet 4 is provided on the inner peripheral side surface of the cylindrical portion 1 c of the rotor yoke 1. Further, the turntable 2 has a placement portion 2a for placing an information recording disc D (hereinafter referred to as a disc) and a centering portion 2b for positioning the disc with respect to the turntable along the center hole of the disc. And attached to the rotor yoke 1.
Although the rotary shaft 3 is attached to the center hole 1a, the rotary shaft 3 may be attached to the turntable 2 and the rotor yoke 1 may be attached to the turntable 2.

On the other hand, in the stator portion S, a cylindrical bearing housing 14 is attached to the stator base 11.
A stator core 12 formed by punching and laminating magnetic metal plates with a press is fixed to the outer peripheral portion 14b of the cylindrical bearing housing 14 by press-fitting through the central annular portion 12a. A central hole 14c of the bearing housing 14 is fixed. The sintered oil-impregnated bearing 15 is press-fitted. A thrust bearing 16 is provided at the bottom of the central hole 14c.
When the rotor portion R is assembled to the stator portion S by inserting the rotating shaft 3 into the bearing 15 at the rotor-side end portion 14a of the bearing housing, the rotor yoke top surface 1b is formed of a magnetic material. A ring-shaped biasing magnet M is provided so that the center thereof coincides with the center of the rotating shaft.

The energizing magnet M is formed with a magnetized region and a non-magnetized region in line symmetry with respect to the operation line L of the pickup A that reads or records information from the disk. That is, in the case of the biasing magnet shown in FIG. 3, the region from the operation straight line L of the pickup A to both sides 90 degrees is magnetized around the rotation axis.
The magnetized region of the biasing magnet in FIGS. 1 to 3 is the side where the pickup is located (the hatched portion of the biasing magnet M in FIG. 3), but is not located in the pickup. The side may be magnetized.

If each part is configured as described above, the magnetized biasing magnet M provided at the portion of the stator portion S facing the rotor yoke top surface 1b causes the rotor yoke 1 attached to the shaft to be connected to the biasing magnet M. The magnet is attracted in the direction F1 of the magnetized region.
As a result, the rotating shaft 3 fixed to the rotor yoke 1 is biased in the direction of the magnetized region F2 of the ring member M, and the clearance between the bearing portion 15 and the shaft 3 in this direction ( The rotor yoke 1 is tilted in the operation linear direction of the pickup so as to eliminate the shaft backlash.
That is, since the biasing magnet M always biases the rotor in the same direction F1, F2 during rotation, it is possible to prevent shaft runout that occurs when the rotor portion R rotates.
In particular, since the F2 direction overlaps the linear movement direction of the pickup, the shaft runout generated in the pickup movement direction (tracking direction T) can be minimized. It is possible to minimize the amount of movement due to shaft runout.

Therefore, it is possible to reduce the runout of the turntable caused by the shaft runout and to prevent an error in reading the information recording disk placed on the turntable.
In addition, a magnetized biasing magnet that generates an attractive force to reduce shaft backlash is provided separately from the drive magnet, so a magnet with an attractive force that matches the characteristics of the motor can be selected. A shaft backlash preventing effect that does not depend on the magnetic force of the magnet can be obtained.
Since the NS pole is magnetized in the axial direction and a magnetic force is applied to the flat top surface b, cogging torque is not generated and smooth rotation can be maintained.
Furthermore, since shaft backlash is prevented in a non-contact manner by magnetic force, problems such as noise and component deterioration due to friction between members do not occur.

  In the embodiment described above, the biasing magnet is provided in the housing. However, as long as it faces the top surface of the rotor yoke of the stator portion, the bearing portion, the stator core, or two or more members The urging magnet can be mounted even across.

Next, a magnetizing biasing magnet M for attracting the rotor yoke used in the present invention in a fixed direction F1 will be described with reference to the drawings.
4A and 4B are a plan view and a sectional view of the biasing magnets M1 and M2, respectively.
The biasing magnet M1 has a ring shape, and is magnetized only in a region within half of the plane (a region having an opening angle of 180 degrees from the center of the ring).
The biasing magnet M2 has an arc shape having an angle of 180 degrees, and the entire region is magnetized.

As described above, if the magnet for attracting the rotor yoke has a ring shape or an arc shape having an angle of 180 degrees, the end portion 14a of the housing viewed from the axial direction is a ring shape, and both portions are Since both have the same shape, it is easy to attach the magnet to the end portion 14a.
If the biasing magnet is provided in the housing so that the center of the ring or the arc shape having an angle of 180 degrees coincides with the center of the rotating shaft, the portion of the rotor yoke at a fixed distance from the rotating shaft center Therefore, the rotor yoke can be attracted in the direction of the magnetized region of the biasing magnet with a stable attracting force at all times. As a result, the rotating shaft fixed to the rotor yoke is always urged to the bearing portion in the radial direction with a constant force, and a stable rotation performance of the motor can be realized.

In addition to this, although not shown in the figure, a biasing magnet that has been magnetized to more than half of the area when viewed from the plane (an area that exceeds the opening angle of 180 degrees from the ring center), or an arc that exceeds the angle of 180 degrees In the case of a biasing magnet that has a shape and is magnetized over the entire area, the force to attract the rotor yoke in the radial direction is reduced, but the axial attracting force can be secured, so the ability to prevent the rotor from coming off is increased. Can be strong.
In addition, it has an urging magnet that is magnetized only in a region that is less than half of the plane as viewed from the plane (a region that is 180 degrees or less from the ring center), or an arc shape that does not exceed an angle of 180 degrees. In the case of a biasing magnet in which only a region or a partial region is magnetized, it is possible to sufficiently secure a radial attractive force if the magnetic force of the magnet is made strong.

Next, with reference to FIG. 5, the measurement result about the shaft runout of the spindle motor using the present invention will be described.
Graph 1 shown in FIG. 5A shows the axial vibration amount in the radial direction when a disk having a diameter of 12 cm is mounted on a turntable and a spindle motor without a biasing magnet is driven to rotate at 1200 rpm. It is a graph.
Graph 2 shown in FIG. 5B shows the amount of axial runout when a disk having a diameter of 12 cm is mounted on a turntable and a spindle motor having a biasing magnet is driven to rotate at 1200 rpm. It is a graph.
The shaft runout is the point P of the rotating shaft measured by paying attention to the movement of the rotating shaft in the radial direction with respect to the rotating shaft 3 moving in the clearance K interposed between the rotating shaft 3 and the bearing 15. This is the amount of movement in FIG. One scale on the graph is 5 μm, and the locus of radial movement of the point P is plotted with dots.
The X axis shown in both graphs indicates a direction perpendicular to the operation line of the pickup, the Y axis indicates the same direction as the operation line of the pickup, and the intersection of the X axis and the Y axis (the origin) ) Is the position of point P shown in FIG. 2 when the spindle motor is stationary.

Referring to graph 1 shown in FIG. 5 (a), the point P of the spindle motor without the biasing magnet is greatly swung in the X-axis and Y-axis directions so as to draw a circle around the origin. You can clearly see how it is.
On the other hand, referring to the graph 2 shown in FIG. 5B, the point P of the spindle motor equipped with the biasing magnet is swung in the X-axis direction, but is in the Y-axis direction. Clearly shows that it is hardly shaken.
In this way, in the case of a spindle motor equipped with a biasing magnet whose center of magnetic force is in a certain direction on the pickup operation line, the shaft runout generated in the direction of the pickup operation line is greatly reduced, and the rotation axis is It is possible to reduce the runout of the fixed turntable.

  Thereby, in particular, the deviation in the track direction between the pickup and the disk placed on the turntable can be minimized, so that tracking errors can be reduced.

Next, the attachment method of the ring member used for this invention is demonstrated along drawing.
FIG. 6A is a longitudinal sectional view showing a state in which the urging magnet M is provided in the metal bearing housing 24.
The end 24a of the housing 24 is provided with a ring-shaped or semi-ring-shaped groove 24b for arranging the urging magnet M, and a protrusion 24c is formed on the end 24a of the housing constituting the groove 24b. Is formed. The biasing magnet M is fixed to the housing 24 by inserting the protrusion 24c after being inserted into the groove 24b.

Next, FIG. 6B is a longitudinal sectional view showing a state in which the rotor yoke biasing magnet M is provided in the resin bearing housing 34.
The end 34a of the housing 34 is provided with a ring-shaped or semi-ring-shaped groove 34b for arranging the biasing magnet M. A claw claw 34c having elasticity for fixing the biasing magnet M is formed at the end 34a of the housing constituting the groove 34b.
The biasing magnet M is inserted into the groove 34b while bending the claw 34c. When the biasing magnet M is disposed at a predetermined position, the claw 34c is restored to its original shape by its own elastic force. Returning, the ring member M is held in the housing end 34a.

FIG. 1 is a longitudinal sectional view of a spindle motor showing an embodiment of the present invention. FIG. 2 is a longitudinal sectional view showing a rotating shaft and a bearing when shaft runout occurs. Fig. 3 (a) shows the positional relationship of the rotary shaft, bearing, biasing magnet, and pickup as seen from the axial direction. FIG. 3 (b) is an enlarged view of the vicinity of the biasing magnet in the diagram shown in FIG. 3 (b). 4A and 4B are a plan view and a cross-sectional view of a biasing magnet for attracting the rotor yoke used in the embodiment. FIG. 5 (a) is a graph showing the axial vibration amount in the radial direction when a disk is mounted on the turntable and the spindle motor is driven to rotate at 1200 rpm. FIG. 5B is a graph showing the amount of axial runout when a disk is mounted on a turntable and a spindle motor having a biasing magnet is driven to rotate at 1200 rpm. FIG. 6A is a diagram showing a method of attaching a biasing magnet for attracting the rotor yoke to a metal bearing housing. FIG. 6B is a view showing a method of attaching the biasing magnet for attracting the rotor yoke to the resin bearing housing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotor yoke 2 Turntable 3 Rotating shaft 14, 24, 34 Housing 15 Bearing part A Pickup L Pickup operation straight line T Tracking direction M, M1, M2 Energizing magnet

Claims (4)

Reproducing / reproducing an information recording disk having a pickup as a head mechanism for reproducing / recording the disk operating on a straight line perpendicular to a track tangent to the information recording disk, and rotating the disk by a spindle motor In the recording device,
A plane part perpendicular to the rotation axis of the spindle motor and a cylindrical part parallel to the rotation axis are formed, and the cylindrical part is fixed integrally with the rotation axis, and an inner peripheral surface of the cylinder part is for driving. A rotor section on which magnets are arranged;
A core made of a magnetic material, a coil wound around the core, a cylindrical bearing housing in which a bearing is provided on the inside and the core is attached on the outside, and a stator portion comprising a base for supporting the bearing housing ,
Information using a spindle motor having a magnetizing region and a non-magnetized region that are axisymmetric with respect to the operation straight line of the pickup, and having a biasing magnet attached to the stator portion so as to face the flat portion Recording disk playback / recording device. 2. The information recording disk reproducing / recording device according to claim 1, wherein the biasing magnet has a ring shape whose outer shape is centered on a rotation axis, and a range of 180 degrees in the ring shape is magnetized. Reproducing / reproducing an information recording disk having a pickup as a head mechanism for reproducing / recording the disk operating on a straight line perpendicular to a track tangent to the information recording disk, and rotating the disk by a spindle motor In the recording device,
A plane part perpendicular to the rotation axis of the spindle motor and a cylindrical part parallel to the rotation axis are formed, and the cylindrical part is fixed integrally with the rotation axis, and an inner peripheral surface of the cylinder part is for driving. A rotor section on which magnets are arranged;
A core made of a magnetic material, a coil wound around the core, a cylindrical bearing housing in which a bearing is provided on the inside and the core is attached on the outside, and a stator portion comprising a base for supporting the bearing housing ,
An information recording disk reproducing / recording using a spindle motor having a magnetizing region formed symmetrically with respect to the operation line of the pickup and having a biasing magnet attached to the stator portion so as to face the flat portion apparatus. 4. The information recording disk reproducing / recording apparatus according to claim 3, wherein the biasing magnet has an outer shape of an arc of 180 degrees centered on the rotation axis, and the entire arc-shaped region is magnetized.

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