JP2008097706A - Disk chucking device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a disk chucking device for achieving the high centering accuracy of a recording disk by enabling a slide cone to smoothly slide in an axial direction without applying lubricating oil. <P>SOLUTION: The disk chucking device is provided with: the slide cone 5 having a conical periphery surface 5b to be engaged with a center hole of a recording disk DK; a coil spring 22 for energizing the slide cone 5 upward in an axial direction; and a chucking plate 6 and a turntable 4 for holding the recording disk DK from the above and below. The slide cone 5 slidably moves in an axial direction among a magnetic yoke 18 fixed to the top end part of a rotating shaft 14, a rotor yoke 3 fixed to a center part of the rotating shaft 14 and the turntable 4. In the cross-sectional shape of the slide cone 5, a straight line connecting the center of an inside sliding surface 5a in an axial direction and the center of the conical periphery surface 5b in an axial direction is almost perpendicular to the conical periphery surface 5b. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a disk chucking apparatus for attaching and detaching a recording disk in a drive apparatus for recording disks such as MD, CD, and DVD.

  As a conventional example of such a disk chucking device, as described in Patent Document 1, for example, a structure in which a recording disk is sandwiched between a turntable and a chucking plate using a magnet is known. Yes.

  FIG. 4 is a cross-sectional view showing a schematic structure of a conventional disk chucking device. In FIG. 4, the bearing housing 102 of the spindle motor 100 is fixed so as to stand upright from the mounting base 101. A rotary shaft 104 is rotatably held in the interior via a sleeve 103, and a turntable 105 is fixed to the upper portion of the rotary shaft 104. A cylindrical boss portion 105 a to which the rotary shaft 104 is press-fitted and fixed is formed at the center portion of the turntable 105.

  A hub retainer 106 is fitted and fixed to the outer peripheral surface of the boss portion 105 a, and a hub 107 having a conical outer peripheral surface 107 a is accommodated between the hub retainer 106 and the turntable 105. The hub 107 is slidable in the axial direction within a range regulated by the hub retainer 106 and the upper surface of the turntable 105, and a coil spring 108 that biases the hub 107 upward is provided between the hub 107 and the turntable 105. It is intervened between. A back yoke 110 and a magnet 111 are fixed to the upper recess of the hub retainer 106.

  A chucking plate 112 is disposed so as to face the turntable 105 with the recording disk DK placed on the turntable 105 interposed therebetween. A magnetic disk 113 attracted by the magnet 111 is fixed at the center of the chucking plate 112.

  When the recording disk DK is loaded on the disk chucking device having the above-described structure, the chucking plate 112 descends toward the turntable 105 and the recording disk is sandwiched between the chucking plate 112 and the turntable 105. Hold it on. At this time, the holding (clamping) state of the recording disk DK is clamped and stabilized by the magnetic attraction acting between the magnetic disk 113 of the chucking plate 112 and the magnet 111 on the turntable 105 side.

  In the chucking operation of the recording disk DK by the above-described disk chucking device, the hub 107 has an important function. As described above, since the hub 107 is biased upward by the coil spring 108, the hub 107 is positioned on the upper end side of the sliding range in the axial direction at the start of the chucking operation. When the recording disk DK is loaded into the disk chucking device and the chucking plate 112 is lowered toward the turntable 105, the center hole inner peripheral part DK1 of the recording disk DK comes into contact with the conical outer peripheral surface 107a of the hub 107. Thus, the centering (alignment) of the recording disk DK is performed.

When the chucking plate 112 is further lowered and the recording disk DK is sandwiched between the chucking plate 112 and the turntable 105, the hub 107 is pushed downward via the recording disk DK. Therefore, the hub is resisted against the biasing force of the coil spring 108. 107 slides downward in the axial direction. At this time, it is necessary that the hub 107 slide smoothly, otherwise the accuracy of the centering of the recording disk DK may be deteriorated. In particular, in the case of a drive device for a recording disk DK such as a high-density DVD, high centering accuracy by a disk chucking device is required. A member corresponding to the hub 107 as described above, that is, a member having a conical outer peripheral surface engaged with the center hole of the recording disk DK and capable of sliding in the axial direction against the urging force is a slide cone. I will say.
Japanese Patent No. 3558268

  In the conventional disk chucking device as described above, as one method for smoothly sliding the slide cone in the axial direction in the chucking operation, a lubricant is applied to the inner sliding surface of the slide cone. It was done. However, when the lubricant is applied manually, it is difficult to manage the application amount, the application location, the uniformity of the application state, and the like, and their variation tends to increase. There is also a possibility that problems such as forgetting to apply, wrong application location, and scattering of lubricant may occur. Although it is possible to eliminate such variations and problems by means such as mechanization, it is desirable to eliminate the necessity of applying a lubricant from the viewpoint of cost reduction.

  In view of the above-described problems, the present invention enables smooth axial sliding of a slide cone without applying a lubricant to a sliding surface in a disk chucking device using a slide cone, thereby recording. The purpose is to ensure high centering accuracy of the disc.

  A disc chucking device according to the present invention includes a turntable fixed to a rotating shaft of a spindle motor, and a conical outer periphery that is slidable in the axial direction at the center of the turntable and engages a center hole of a recording disc. A slide cone having a surface; biasing means for biasing the slide cone in a direction away from the turntable; a chucking plate disposed to face the turntable; the chucking plate and the turntable And a means for generating a magnetic attraction force for maintaining the state where the recording disk is sandwiched between the slide cone and the slide cone in the cross-sectional shape of the conical outer peripheral surface. A straight line connecting the axial center and the axial center of the inner sliding surface is substantially perpendicular to the conical outer peripheral surface. And characterized in that (claim 1).

  According to such a structure, the recording disk is loaded on the disk chucking device, the chucking plate moves toward the turntable, and the center hole of the recording disk contacts the conical outer peripheral surface of the slide cone. The recording disk is centered. At this time, the slide cone is pushed toward the turntable via the recording disk, and therefore slides in the axial direction against the urging force. The force that the recording disk (the inner periphery of the center hole) pushes the slide cone in the axial direction can be divided into a component force in a direction perpendicular to the conical outer peripheral surface of the slide cone and a component force in a direction parallel to the component. . Among these, it is considered that the component force in the direction perpendicular to the conical outer peripheral surface of the slide cone causes rattling which inhibits the slide cone from sliding in the axial direction.

  In the structure of the present invention, in the cross-sectional shape of the slide cone, a straight line connecting the axial center of the conical outer peripheral surface and the axial center of the inner sliding surface is substantially perpendicular to the conical outer peripheral surface. A component force in a direction perpendicular to the conical outer peripheral surface of the slide cone acts near the axial center of the inner sliding surface of the slide cone. As a result, rattling during sliding due to the clearance between the inner sliding surface of the slide cone and the sliding counterpart (rotating shaft) is less likely to occur, and smooth sliding is ensured.

  In a preferred embodiment of the disk chucking device according to the present invention, one of a magnet and a magnetic yoke constituting the means for generating the magnetic attraction is fixed to the center of the chucking plate, and the other of the magnet and the magnetic yoke is the The slide cone is fixed to the tip of the rotating shaft of the spindle motor, and the slide cone is slidably disposed with respect to the rotating shaft between the other of the magnet and the magnetic yoke and the turntable.

  According to such a configuration, the magnet or magnetic yoke, which is a member on the turntable side among the means for generating magnetic attraction, can be easily fixed to the tip of the rotating shaft by means such as press fitting. Moreover, the magnet or magnetic yoke fixed to the tip of the rotating shaft also functions as a slide cone removal prevention function and a sliding range regulating member. That is, the slide cone is slidable in the axial direction between the magnet or magnetic yoke and the turntable, and there is no need to separately provide a slide cone retaining member or a sliding range regulating member. Therefore, effects such as reduction in the number of parts and cost reduction can be obtained.

  In another preferred embodiment of the disk chucking apparatus according to the present invention, the slide cone is made of polyacetal or a resin material having high sliding characteristics equivalent to the polyacetal (claim 3).

  According to this configuration, the slide cone can be formed at low cost by resin injection molding, and smooth sliding in the axial direction of the slide cone in the chucking operation can be ensured. In addition, since materials such as polyacetal have a relatively small change in surface roughness due to wear, management of the surface roughness is relatively easy.

  In another preferred embodiment of the disk chucking device according to the present invention, the surface roughness of the inner sliding surface of the slide cone is Ry 5 to 20 μm (Claim 4).

  According to this configuration, since the contact area between the inner sliding surface of the slide cone and the sliding partner is smaller than when the surface roughness is less than Ry5, the axial direction of the slide cone in the chucking operation is smoother. Smooth sliding can be ensured. On the other hand, when the surface roughness increases to exceed 20 μm, the inner sliding surface of the slide cone wears quickly, and the clearance between the sliding partner increases and the slide cone axial sliding characteristics deteriorate over time. It tends to occur. Therefore, it is preferable to manage the surface roughness within the above range.

  As described above, the disk chucking device of the present invention improves the axial sliding characteristics in the chucking operation by devising the shape and structure of the slide cone, so that the lubricant is applied to the sliding surface. Therefore, it is possible to smoothly slide the slide cone in the axial direction, thereby ensuring a high centering accuracy of the recording disk.

  Embodiments of the present invention will be described below with reference to the drawings. In the following description, when describing the positional relationship and direction of each member vertically and horizontally, it means the positional relationship and direction in the drawings to the last, and it means the positional relationship and direction when incorporated in an actual device. is not.

  FIG. 1 is a cross-sectional view showing a schematic structure of a disk rotation driving apparatus having a disk chucking apparatus according to an embodiment of the present invention. This disk rotation driving device is composed of a spindle motor 2 fixed to a mounting base 1, a turntable 4 fixed to a rotor yoke 3, a slide cone 5 and a chucking plate 6 constituting a disk chucking device, and other members. Has been.

  The spindle motor 2 includes a bearing housing 7, a bearing sleeve 8, a cap 9, a thrust plate 11, a rotor yoke 3, a rotor magnet 12, a stator armature 13, a rotating shaft 14, and the like. As shown in FIG. 1, a substantially cylindrical bearing housing 7 is fixed so as to stand upright from the mounting base 1. A metal bearing housing 7 is inserted from the upper side of the through hole formed in the central portion of the mounting base 1, and the bearing housing 7 is fixed to the mounting base 1 by caulking at the lower outer peripheral edge portion thereof.

  A bearing sleeve 8 made of oil-impregnated sintered metal is fixed inside the bearing housing 7, and a rotating shaft 14 is rotatably held inside the bearing sleeve 8. A cap 9 for closing the lower end side opening of the bearing housing 7 is provided, and the cap 9 is fixed to the bearing housing 7 by caulking at the lower end portion of the bearing housing 7. A groove is formed in the outer peripheral surface near the lower end of the rotating shaft 14, and a retaining ring 15 that engages with the groove is disposed between the step near the lower end of the bearing housing 7 and the inner surface of the cap 9. Further, the lower end surface of the rotating shaft 14 is formed as a convex surface, and the thrust plate 11 that supports the lower end surface is disposed at the center of the inner surface of the cap 9.

  A stator armature 13 having a plurality of poles is fixed to the outer peripheral surface of the bearing housing 7. The stator armature 13 includes a core formed by laminating a plurality of electromagnetic steel sheets each having a plurality of salient poles formed at predetermined intervals in the circumferential direction, and a coil wound around each salient pole of the core. The stator armature 13 is fixed to the outer peripheral surface of the bearing housing 7 by press-fitting (and bonding) the inner peripheral surface of the core into the step portion of the outer peripheral surface of the bearing housing 7. In addition, the lead wire of the coil of the stator armature 13 is connected to the FPC circuit board 16 attached to the upper surface of the mounting base 1. On the FPC circuit board 16, a drive circuit for the spindle motor 2, a hall element for detecting the number of rotations, and the like are mounted.

  The central portion of the rotor yoke 3 is fixed near the center of the rotating shaft 14. A cylindrical portion protruding upward is formed at the center of the rotor yoke 3, and the rotor shaft 3 and the rotation shaft 14 are fixed by press-fitting (and bonding) the rotation shaft 14 into the cylinder portion. The outer peripheral portion of the rotor yoke 3 is a cylindrical portion protruding downward, and a cylindrical rotor magnet 12 is bonded and fixed to the inside thereof. A predetermined gap is secured between the inner peripheral surface of the rotor magnet 12 and the outer peripheral surface of the stator armature 13 (core).

  On the upper surface of the rotor yoke 3, a turntable 4 that supports and rotates the lower surface of the recording disk DK is fixed. Near the outer periphery of the upper surface of the turntable 4, a thin rubber ring 17 is attached, and the upper surface of the rubber ring 17 comes into contact with the lower surface of the recording disk DK.

  A magnetic yoke 18 is fixed to the upper end of the rotating shaft 14. The rotary shaft 14 and the magnetic yoke 18 are fixed by press-fitting (and adhering) the upper end of the rotary shaft 14 into the central hole of the substantially cylindrical magnetic yoke 18. The magnetic yoke 18 generates a magnetic attractive force with the magnet 19 fixed to the lower surface of the central portion of the chucking plate 6.

  The chucking plate 6 is disposed (upward) so as to face the turntable 4 with the recording disk DK placed on the turntable 4 interposed therebetween. When the recording disk DK is loaded onto the disk rotation driving device, the chucking plate 6 descends toward the turntable 4 and is held so as to sandwich the recording disk between the chucking plate 6 and the turntable 4. . At this time, the holding (clamping) state of the recording disk DK is clamped and stabilized by the magnetic attraction acting between the magnet 19 fixed to the chucking plate 6 and the magnetic yoke 18 fixed to the upper end of the rotating shaft 14. To do. A thin rubber ring 21 is attached near the outer periphery of the lower surface of the chucking plate 6, and the lower surface of the rubber ring 21 contacts the upper surface of the recording disk DK.

  In addition, a slide cone 5 that is movable in the vertical direction along the rotation shaft 14 is provided between the lower surface of the magnetic yoke 18 and the upper surface of the turntable 4. A cylindrical inner sliding surface 5 a that slides in the axial direction along the outer peripheral surface of the rotating shaft 14 is formed at the center of the slide cone 5. On the outer peripheral surface of the slide cone 5, a conical outer peripheral surface (tapered surface) 5b that extends downward is formed. The conical outer peripheral surface 5b engages with the center hole inner peripheral portion DK1 of the recording disk DK.

  Further, a coil spring 22 is interposed between a recess formed on the lower surface of the slide cone 5 and an upper surface step portion of the turntable 4. The coil spring 22 has a function of urging the slide cone 5 slidable within a predetermined range along the rotation shaft 14 upward (in a direction away from the turntable 4). The upper limit position of the range in which the slide cone 5 can move in the axial direction is a state where the upper surface of the central portion of the slide cone 5 is in contact with the lower surface of the magnetic yoke 18 (the state shown in FIG. 1). The lower surface of the central portion (cylindrical portion) of 5 is in contact with the upper surface of the central portion of the turntable 4 (or the upper surface of the central cylindrical portion of the rotor yoke 3). Therefore, when the recording disk DK is not loaded on the disk rotation driving device, the slide cone 5 is biased upward by the coil spring 22 and is in the upper limit position (the state shown in FIG. 1).

  The recording disk DK is chucked by the disk chucking device including the turntable 4, the slide cone 5, the chucking plate 6 and the like as described above. When the recording disk DK is loaded onto the disk rotation driving device, the chucking plate 6 descends toward the turntable 4 and the lower surface of the chucking plate 6 presses the recording disk DK downward via the rubber ring 21. As a result, the conical outer peripheral surface 5b of the slide cone 5 is pushed downward by the center hole inner peripheral portion DK1 of the recording disk DK, so that the slide cone 5 slides downward in the axial direction against the biasing force of the coil spring 22. . At this time, centering (alignment) with respect to the rotating shaft 14 of the recording disk DK is performed.

  FIG. 2 is a view for explaining the characteristics of the cross-sectional shape of the slide cone and the reason thereof in the present embodiment. 2A and 2B, only the portion on the right side of the rotary shaft 14 is drawn in the cross section of the slide cone 5. As shown in FIG. 2A, the force F in which the center hole inner peripheral portion DK1 of the recording disk DK pushes the conical outer peripheral surface 5b of the slide cone 5 downward is a component force in a direction parallel to the conical outer peripheral surface 5b. (Friction force) Fa and component force (pressure) Fb in a direction perpendicular to the conical outer peripheral surface 5b can be considered separately. The component force Fb in the direction perpendicular to the conical outer peripheral surface 5b is considered to cause rattling that inhibits the sliding of the slide cone 5 in the axial direction. This rattling is caused by the clearance existing between the inner sliding surface 5a of the slide cone 5 and the outer peripheral surface of the rotary shaft 14.

  As shown in FIG. 2A, the cross-sectional shape of the slide cone 5 (particularly, the component force Fb in the direction perpendicular to the conical outer peripheral surface 5b is directed toward the axial center of the inner sliding surface 5a of the slide cone 5 (particularly, It has been found that if the inclination of the conical outer peripheral surface 5b is designed, the shakiness of the slide cone 5 due to the clearance is reduced. Therefore, as shown in FIG. 2B, the slide cone 5 of the present embodiment has a straight line (imaginary line) IL connecting the axial center of the conical outer peripheral surface 5b and the axial center of the inner sliding surface 5a. The cross-sectional shape is perpendicular to the conical outer peripheral surface 5b.

  Note that the center hole of the recording disk DK is within the range of φ15.0 mm to 15.15 mm in the case of a CD or DVD. That is, the allowable variation of the center hole diameter is 0.15 mm in the standard. In this case, the minimum diameter (upper end side) of the conical outer peripheral surface 5b needs to be less than φ15.0 mm, and the maximum diameter (lower end side) needs to exceed φ15.15 mm. Further, due to the variation in the center hole diameter and the variation in the outer diameter of the slide cone 5, the lower end edge of the inner peripheral portion DK1 of the center hole of the recording disk DK is not always in contact with the axial central portion of the conical outer peripheral surface 5b. However, the above relationship is desirable in design. That is, in the cross-sectional shape of the slide cone 5, if a straight line (imaginary line) IL connecting the axial center of the conical outer peripheral surface 5b and the axial center of the inner sliding surface 5a is substantially perpendicular to the conical outer peripheral surface 5b. Good.

  Next, as a second device for smoothly sliding the slide cone 5 along the outer peripheral surface of the rotary shaft 14, the slide cone 5 is formed of polyacetal, and the surface roughness of the inner sliding surface 5a is further increased. Is formed so that Ry is 5 to 20 μm. Polyacetal is a crystalline thermoplastic resin sometimes referred to as acetal resin or POM, and is widely used as a material for machine element parts such as gears, screws, and bearings. By using polyacetal as the material of the slide cone 5, the change in the surface roughness due to wear is relatively small, and the management of the surface roughness is relatively easy.

  Further, the reason why the surface roughness of the inner sliding surface 5a is Ry5 to 20 μm is that the inner sliding surface 5a of the slide cone 5 and the outer peripheral surface of the rotary shaft 14 are compared to the case where the surface roughness is less than Ry5. This is to reduce the contact area and ensure smoother sliding of the slide cone 5 in the axial direction in the chucking operation.

  FIG. 3 is a graph of experimental results showing the relationship between the surface roughness and the frictional force of the sample block formed of polyacetal. In this experiment, a predetermined weight (three types of loads 37 gf, 98 gf, and 232 gf) was placed on the sample block and pulled horizontally on a flat table, and the moment when the sample block started to move was measured as a frictional force. FIG. 3 is a graph in which the horizontal axis represents the surface roughness Ry (μm) of the lower surface of the sample block and the vertical axis represents the frictional force (N).

  As can be seen from FIG. 3, when the surface roughness Ry is in the range of 0 to 15 μm, the frictional force decreases as the surface roughness Ry increases. Further, the frictional force suddenly increases when the surface roughness Ry becomes smaller than about 5 μm as a boundary. Therefore, the surface roughness of the conical outer peripheral surface 5b of the slide cone 5 of this embodiment is set to Ry5 or more. On the other hand, when the surface roughness is increased to exceed 20 μm, the inner sliding surface of the slide cone 5 is quickly worn, and the clearance between the outer peripheral surface of the rotary shaft 14 is increased, and the sliding cone 5 is in a sliding state. It was found that rattling is likely to occur. In other words, the deterioration with time of the axial sliding characteristics of the slide cone 5 due to rattling proceeds. Therefore, the surface roughness of the conical outer peripheral surface 5b of the slide cone 5 of this embodiment is determined to be Ry20 or less.

  As described above, in the chucking device of the present embodiment, in the cross-sectional shape of the slide cone 5, a straight line (imaginary line) IL connecting the axial center of the conical outer peripheral surface 5b and the axial center of the inner sliding surface 5a. Since the slide cone 5 is made of polyacetal and the surface roughness of the conical outer peripheral surface 5b is Ry5 to 20 μm, the chucking operation is performed. The sliding movement of the slide cone 5 in the vertical direction is performed smoothly. As a result, even if the application of lubricant between the inner sliding surface 5a of the slide cone 5 and the rotary shaft 14 is abolished, the slide cone 5 can be smoothly slid in the axial direction. High centering accuracy of DK can be secured.

  As mentioned above, although the Example of this invention was described, this invention is not necessarily limited by this Example. The present invention can be implemented by appropriately changing the above-described embodiments. For example, the material of the slide cone 5 is not limited to polyacetal, and may be formed of a resin material having high sliding characteristics (and abrasion resistance) equivalent to that.

  In the configuration of the above embodiment, the chucking plate 6 is provided with the magnet 19, the magnetic yoke 18 is fixed to the upper end of the rotating shaft 14, and the recording disk DK is held (clamped) by the magnetic attraction acting between them. However, conversely, it is also possible to employ a configuration in which a magnetic yoke is provided on the chucking plate 6 and a magnet is fixed to the upper end portion of the rotating shaft 14.

  In addition, the material of each member demonstrated in the said Example, the shape of each member shown in each figure, a structure, etc. are only examples. It is possible to implement the present invention by changing the material, shape, structure, and the like of each member as necessary.

It is sectional drawing which shows schematic structure of the disc rotational drive apparatus which has a disc chucking apparatus based on the Example of this invention. It is a figure for demonstrating the characteristic of the cross-sectional shape of the slide cone in a present Example, and its reason. It is a graph of the experimental result which shows the relationship between the surface roughness of the sample block formed with the polyacetal, and the frictional force. It is sectional drawing which shows schematic structure of the disc chucking apparatus which concerns on a prior art example.

Explanation of symbols

2 spindle motor 4 turntable 5 slide cone 5a inner sliding surface 5b conical outer peripheral surface 6 chucking plate 14 rotating shaft 18 magnetic yoke (means for generating magnetic attractive force)
19 Magnet (Means for generating magnetic attraction)
22 Coil spring (biasing means)
DK recording disc

Claims (4)

A turntable fixed to the spindle of the spindle motor;
A slide cone that is slidable in the axial direction at the center of the turntable and has a conical outer peripheral surface that engages with the center hole of the recording disk;
A biasing means for biasing the slide cone in a direction away from the turntable;
A chucking plate arranged to face the turntable;
A disk chucking device comprising: means for generating a magnetic attraction for maintaining a state in which the recording disk is sandwiched between the chucking plate and the turntable;
The slide cone has a cross-sectional shape in which a straight line connecting the axial center of the conical outer peripheral surface and the axial center of the inner sliding surface is substantially perpendicular to the conical outer peripheral surface. King device. One of a magnet and a magnetic yoke constituting the means for generating the magnetic attraction is fixed to the central portion of the chucking plate, and the other of the magnet and the magnetic yoke is fixed to a tip of a rotating shaft of the spindle motor, 2. The disk chucking device according to claim 1, wherein the slide cone is slidably disposed with respect to the rotation shaft between the other of the magnet and the magnetic yoke and the turntable. 3. The disk chucking device according to claim 1, wherein the slide cone is made of polyacetal or a resin material having high sliding characteristics equivalent to the polyacetal. The disc chucking device according to claim 1, 2, or 3, wherein a surface roughness of an inner sliding surface of the slide cone is Ry of 5 to 20 µm.

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