Disc clamping mechanism by which a disc is held and rotated

A cylindrical member is fixed to an upper portion of a rotary shaft and a clamper presses an optical disc in contact with the top of a turntable. The structure is such that a first bottom face of the cylindrical member that faces a clamping magnet in the axial direction is positioned below an opposite face of the clamper that faces the clamping magnet in the axial direction.

BACKGROUND OF THE INVENTION

The present invention relates to a disc clamping mechanism whereby an optical disc or a magneto-optical disc or the like is held and rotated.

Disc drive devices equipped with head mechanisms for reading information recorded on a disc or writing information to a disc are known in the form of devices for optical discs such as CDs, DVDs and MDs, and for magneto-optical discs.

With disc drive devices, a turntable of a spindle motor, by which a disk is rotationally driven, must be in pressing contact with and hold the disc. Thus, in disc drive devices, a clamper is provided that is in direct contact with the top face of a disc that is placed on the turntable, and a clamping magnet is provided in the center of the turntable of the spindle motor so as to attract the clamper.

For example, in Japanese Patent Laid-Open Publication No. 2000-156007, a device such as shown inFIG. 15andFIG. 16is disclosed.FIG. 15shows the state before the clamper is attached to the turntable, andFIG. 16shows the state of the clamper being attached to the turntable.

As shown in the drawing, a spindle motor131comprises a motor body132and a rotary shaft133, and a turntable134, on which an optical disc150is placed, is mounted in the rotary shaft133. A placing face135, on which the optical disc150is placed, is formed on the outer circumference of the turntable134. In the inner circumference of the placing face135, a disc guide137, which protrudes toward upwards from the placing face135, is formed. When the optical disc150is placed on the placing face135, the disc guide137is fit in a central hole151of the optical disc150, in order to position the optical disc.

In the inner circumference of the disc guide137, a recess138is formed. In the recess138, a clamping magnet139, which attaches a clamper145, and a yoke140for controlling the magnetic resistance of the clamping magnet139, are disposed. Furthermore, the inner circumference of the disc guide137has an insertion hole141, which is positioned at the approximate center of the turntable134, and through which the rotary shaft133of the spindle motor131passes. The rotary shaft133of the spindle motor is attached to the insertion hole141, and the turntable134turns together with the rotary shaft133.

The clamper145, which holds the turntable134together with the optical disc150, at the approximate center thereof, has a through-hole146, through which passes a locking protrusion129, which is provided in a cover128that constitutes a portion of a case for an optical disc device.

A locking piece147is locked by way of the locking protrusion129that is provided in the cover128being inserted in the through-hole146, and by way of a stopper130that is mounted on the tip of the locking protrusion129, thus allowing the clamper145to be mounted so as to be mobile with respect to the upper cover128. On the outer circumference of the locking piece147, a positioning protrusion148is provided for positioning the clamper145in relation to the turntable134. The clamper145is positioned in relation to the turntable134by way of the positioning protrusion148being fit along the circumference of the recess138, which is provided in the turntable134. In addition, in the outer circumference of the clamper145, corresponding to the placing face135of the turntable134, a disc pressing portion149is formed that is in direct contact with the optical disc150and clamps the optical disc150together with the placing face135.

As shown above, eccentricity during rotation of the optical disc150is controlled by way of accurately positioning on the turntable134of the clamper145, so that suitable recording and playback of the optical disc can be performed.

Furthermore, when the clamper145is attached to the turntable134, because the configuration is such that the optical disc150is clamped in between the disc pressing portion149of the clamper145and the placing face135of the turntable134, the optical disc150can be held securely by the turntable134and clamper145.

However, although the clamping magnet139and yoke140are fixed in the recess138with adhesive or the like, if, for example, the adhesive strength decreases due to degradation of the adhesive or the like, there is a risk of the clamping magnet139coming off and detaching from the turntable due to shocks resulting from the effect of magnetic attraction when a disc is mounted or removed, vibrations due to fast rotation of the spindle motor, or the like. If the clamping magnet139is detached from the turntable, with the conventional device above, the clamping magnet139attaches to the clamper145, the optical disc150cannot be held by the turntable134and clamper145, and stable disc driving cannot be achieved.

SUMMARY OF THE INVENTION

One or more of the embodiments of the present invention solves the aforementioned problems of the prior art and provides a disc clamping mechanism that can clamp a disc in state in which it is in contact with a turntable top, even when the clamping magnet is detached from the turntable, and thus can perform stable disc driving.

According to one or more embodiments of the present invention, the disc clamping mechanism:is provided with a spindle motor M1(M2), having a turntable hat rotates united with a rotary shaft22, on which a disc40is placed, and a clamper30A, which is positioned in the upper part of the spindle motor M1(M2), comprising:a disc guide23(53) that guides the inner edge of the disc;a clamping magnet27, which is disposed in the inner diameter of the disc guide23(53), anda cylindrical member28(58), which is fixed to the upper portion of the rotary shaft22, whereinthe cylindrical member28(58) has a first bottom face28c(58c) that faces the clamping magnet27in the axial direction with a gap H1therebetween; andthe first bottom face28c(58c), in a state in which the clamper30A presses the disc40in contact with the top of the turntable, is positioned below a facing part33of the clamper30A, which faces the clamping magnet27in the axial direction,

In the aforementioned structure, the disc guide23may have an annular recess23b, and the clamping magnet27may be disposed in the recess23b; the cylindrical member28may have a second bottom face28din the inner diameter of the first bottom face28c; and the second bottom face28dmay face the disc guide23in the axial direction with a gap H2therebetween. In this case, it is preferable that: the gap H1is larger than the gap H2; and in a state in which the clamper30A presses the disc40in contact with the turntable top, with a gap H3being the minimum gap in the axial direction between the disc guide23and the clamper30A, the gap H3is larger than the gap H2. Furthermore, it is preferable that the gap H1is no greater than the gap H2; and in a state in which the clamper30A presses the disc40in contact with the turntable top, with a gap H3being the minimum gap in the axial direction between the disc guide23and the clamper30A, the gap H3is larger than the gap H1.

Furthermore, in the aforementioned structure, the disc guide23may have an annular recess23b, and the clamping magnet27may be disposed in the recess23b; the cylindrical member28may have a second bottom face28din the inner diameter of the first bottom face28c; and the second bottom face28dmay be in direct contact with the disc guide23.

Furthermore, in the aforementioned structure, the disc guide53may have a through-opening, and the clamping magnet27may be disposed in the through-hole and abut against the turntable.

Furthermore, in the aforementioned structure, the clamper may have a positioning hole or a positioning recess, and the cylindrical member may have an outer circumference that is fitted in the positioning hole or positioning recess of the clamper. In this case, it is preferable that the cylindrical member has an inclined face on the upper portion of the outer circumference, and the outer diameter gradually decreases in the upward direction.

Furthermore, with the aforementioned structure, the cylindrical member is preferably made from a non-magnetic material.

According to one or more embodiments of the present invention, even if a clamping magnet were to detach and rise from the turntable, the clamping magnet would be stopped by abutting against the first bottom face of the cylindrical member, and thus not attaching to the clamper. Thus, even if the clamper magnet detaches from the turntable, the disc can be clamped in a state in which it is in pressing contact with the turntable, and stable disc drive can be achieved.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter embodiments of the present invention are described by way of example based on the drawings.

First Embodiment

First, the configuration of a spindle motor according to a first embodiment of the present invention is described by way ofFIG. 1.FIG. 1is a side view of a spindle motor M1of this example, and the right half of the drawing is shown as a cross-section. The spindle motor M1primarily comprises a stator S and a rotor R.

The stator S has a bearing unit comprising a bearing holder12and a bearing13, a stator core14that is disposed around the bearing unit, a core cover15, and a coil16.

The bearing holder12is fixed to a base11, wherein a steel plate is layered and mounted on a so-called iron substrate, on the surface of which a printed circuit is formed, or a printed wiring board is overlaid. The sintering metal of the cylinder is impregnated with a lubricating oil, and the bearing13is fixed to the inner circumference of the bearing holder12by way of press-fitting or the like. Note that on the base11, a Hall element (not shown) is provided facing a driving magnet25, which is described below, so that the rotation of the rotor R can be detected by way of the Hall element.

The stator core14comprises a planar core laminate, on which a plurality of salient poles are formed, and is fixed to the outer circumference of the bearing holder12. On the surface of the stator core14, the core cover15, which is made from an insulating resin, is disposed; the coil16is wound on with the core cover15therebetween.

The rotor R has a rotary shaft22, which is rotatably supported in the bearing unit; a rotor case21, that rotates united with the rotary shaft22; and the driving magnet25, which is fixed to the rotor case21.

The rotor case21is formed into a cap shape with a magnetic plate, and has a cylinder part21a, which is formed into a cylinder coaxial with the rotary shaft22, and a upper face21b, wherein the inner diameter has slightly lower profile. The rotary shaft22is fixed to a burring21c, which is provided in the center of the upper face21bof the rotor case21, by way of press-fitting, and is supported in a rotatable state by the bearing13.

The annular driving magnet25, which faces the salient poles of the stator core14in the radial direction, is mounted in the interior of the cylinder part21aof the rotor case21. The driving magnets25are N/S alternatingly multipole-magnetized in the circumferential direction. The upper face21bof the rotor case21serves as the turntable, which rotates united with the rotary shaft22, and on which a disc is removably disposed. Moreover, a disc guide23is disposed in the inner diameter of the upper face21b, and a friction sheet24is disposed in the outer diameter of the upper face21b.

The disc guide23is a part for guiding a disc concentric with the rotary shaft22, and is fixed in place by an inside upright portion23abeing press-fit against the outer circumference of the barring part21cof the rotor case21. The disc guide23is formed from a hard resin and has a recess23bat the outer circumference of the upright portion23a, a plurality of guide claws23cbeing provided in the outer circumference of the recess23bat equal intervals in the rotational direction. The claws23care in direct contact with the inner edge of the central hole in the disc.

A yoke plate26and a clamping magnet27are disposed in the recess23bof the disc guide23. The yoke plate26and the clamping magnet27are both formed into an annular shape. The yoke plate26serves as a back yoke for the clamping magnet27and is formed from a magnetic body. The clamping magnet27magnetically attracts a clamper, which is described below, and attracts the clamper toward the turntable (toward the upper face21b).

A cylindrical member28is press-fit into the upper portion of the rotary shaft22. As shown inFIG. 2, the upper part of the outer circumference28aof the cylindrical member28of this example is an inclined face28b, and the outer diameter gradually decreases in the upward direction. Details are described below, but the outer circumference28a, which includes the inclined face28b, centers the clamper. Furthermore, the bottom face of the cylindrical member28of this example is step-shaped, and has a first bottom face28con outer diameter and a second bottom face28don the inner diameter, which is lower than the first bottom face28c.

As shown inFIG. 1, the structure is such that the outer diameter of the outer circumference28aof the cylindrical member28is larger than the inner diameter of the clamping magnet27, and the first bottom face28cof the cylindrical member28faces the clamping magnet27in the axial direction with a prescribed gap therebetween. Thus, with the spindle motor M1of this example, even if the clamping magnet27were to detach and float from the recess23bof the disc guide23, the clamping magnet27is stopped by abutting against the first bottom face28cof the cylindrical member28.

Furthermore, the second bottom face28dof the cylindrical member28faces the upright portion23aof the disc guide23in the axial direction with a prescribed gap therebetween. Thus, with the spindle motor M1of this example, even if the disc guide23were to rise from the upper face21bof the rotor case21, the disc guide23is stopped by abutting against the second bottom face28dof the cylindrical member28.

Note that, in the present example, there are no particular restrictions on the material for the cylindrical member28, but non-magnetic materials are preferred over magnetic materials, and non-magnetic metallic materials, such as brass, which has excellent durability and workability, are particularly preferable. The reason for this is that, because the outer diameter of the outer circumference28aof the cylindrical member28is larger than the inner diameter of the clamping magnet27, the cylindrical member28must be assembled with the rotary shaft22after the clamping magnet27is assembled, and if the cylindrical member28is made from a magnetic material, then an excessive attractive force is received from the clamping magnet27during assembly, thus making assembly difficult.

Furthermore, in the present invention, because a gap is provided between the first bottom face28cof the cylindrical member28and the clamping magnet27, even if the cylindrical member28is made from a metallic material, such as brass, there is no force applied to the clamping magnet27when press-fitting the cylindrical member28, thus there is no risk of damaging the clamping magnet27.

Next, a disc clamping mechanism that uses the spindle motor M1of this example is described usingFIG. 3.FIG. 3(a) shows the state before an optical disc is held, andFIG. 3(b) shows the state of the optical disc being held.

InFIG. 3,30A is the clamper, and40is an optical disc. The spindle motor M1and the clamper30A are suitably supported in the case of a disc drive device, which is not shown. The clamper30A is positioned toward the top of the spindle motor M1and presents an overall disc shape, wherein at least the portion that faces the clamping magnet27(opposite face33) is formed from a magnetic body. In the center of the clamper30A, a positioning hole31ais provided that has an inner diameter that is slightly larger than the outer circumference28aof the cylindrical member28. Furthermore, a disc pressing portion32is provided at the outer circumference of the clamper30A.

When the optical disc40is transported to the space between the spindle motor M1and the clamper30A, as shown inFIG. 3(a), the spindle motor M1is raised. Thereupon, as shown inFIG. 3(b), the plurality of guide claws23cof the disc guide23are in direct contact with the inner edge of the central hole40aof the optical disc40, and the optical disc40is automatically centered. Meanwhile, the clamper30A is automatically centered by way of being attracted by the clamping magnet27and the positioning hole31abeing guided along the inclined face28band the outer circumference28aof the cylindrical member28. Note that, because the upper part of the outer circumference28aof the cylindrical member28of this example is the inclined face28b, wherein the outer diameter gradually decreases in the upward direction, even if the centers of the clamper30A and the rotary shaft22are slightly out of alignment, the clamper30A will be suitably centered along the inclined face28b. Consequently, the disc pressing portion32of the clamper30A stably holds the optical disc40in the gap with the upper face21bof the rotor case21, and eccentricity when the optical disc40is rotated by way of driving the spindle motor M1is controlled, thus allowing suitable recording and playback of the optical disc40.

Thus, with the disc clamping mechanism of this example, the outer circumference28a, which is fitted in the positioning hole31aof the clamper30A, and the cylindrical member28, which has the first bottom face28cthat faces the clamping magnet27in the axial direction, are fixed in the upper portion of the rotary shaft22. Consequently, even if a need to change the shape of the disc guide were to arise, the clamper can be positioned by the cylindrical member without changing the clamper. That is to say, clampers of the same shape can be used regardless of the shape of the disc guide on the turntable.

Next, the positional relationship among the parts in the disc clamping mechanism of this example is described in detail usingFIG. 4. With the disc clamping mechanism of this example, the first bottom face28cof the cylindrical member28faces the clamping magnet27in the axial direction with a gap H1therebetween, and the second bottom face28dof the cylindrical member28faces the upright portion23aof the disc guide in the axial direction with a gap H2therebetween. Furthermore, as inFIG. 4, in a state where the clamper30A presses the optical disc40in contact with the turntable top, the first bottom face28cof the cylindrical member28is positioned lower than the opposite face33of the clamper30A that faces the clamping magnet27in the axial direction. That is to say, the gap H1is established smaller than the gap H0. Consequently, with the disc clamping mechanism of this example, even if the clamping magnet27were to detach and rise from the turntable, the clamping magnet27is stopped by abutting against the first bottom face28cof the cylindrical member28, and does not touch the clamper30A. Thus, even if the clamping magnet27were to detach from the turntable, the clamping magnet27will not attach to the clamper30A, the optical disc40can be clamped in a state in which it is in pressing contact with the turntable top, and a stable disc drive can be achieved.

Furthermore, with the disc clamping mechanism of this example, the gap H1is established larger than the gap H2. And, as inFIG. 4, in a state in which the clamper30A presses the optical disc40in contact with the turntable top, with a gap H3being the minimum gap in the axial direction between the disc guide23and the clamper30A, then the gap H3is established larger than the gap H2. Consequently, with the disk clamping device of this example, even if the disc guide23, which houses the clamping magnet27, were to rise from the turntable, the disc guide23is stopped by abutting against the second bottom face28dof the cylindrical member28, and the disc guide23will not push up the clamper30A. Thus, even if the disc guide23were to rise from the turntable, the optical disc40can be clamped in a state in which it is in pressing contact with the turntable, and a stable disc drive can be achieved.

Note that although the gaps of the parts in the disc clamping mechanism of this example have the following relationship:
0<H1<H0,
0<H2<H1, and
H2<H3;
configurations such as the variants ofFIG. 5or6, for example, are also possible.

With the variant ofFIG. 5, the gaps for the parts of the disc clamping mechanism have the following relationship:
0<H1<H0,
H1≦H2, and
H1<H3.

Also in the disc clamping mechanism ofFIG. 5, if the clamping magnet27rises from the turntable, the clamping magnet27is stopped by abutting against the first bottom face28cof the cylindrical member28, and does not touch the clamper30A. Furthermore, even if the disc guide23were to rise from the turntable, the clamping magnet27would be stopped by abutting against the first bottom face28cof the cylindrical member28, so that the disc guide23would not touch the clamper30A. Thus, even if the clamping magnet27or disc guide23were to rise from the turntable, the optical disc40would be able to be clamped in a state in which it is in pressing contact with the turntable, and stable disc drive would be possible.

In the variant ofFIG. 6, the gaps for the parts of the disc clamping mechanism have the following relationship:
0<H1<H0, and
H2=0.

Also in the disc clamping mechanism ofFIG. 6, if the clamping magnet27rises from the turntable, the clamping magnet27is stopped by abutting against the first bottom face28cof the cylindrical member28, and does not touch the clamper30A. Furthermore, because the disc guide23abuts against the second bottom face28dof the cylindrical member28, the disc guide23will not rise from the turntable, and the disc guide23will not push up the clamper30A. Thus, the optical disc40can be clamped by the clamper30A in a state in which it is in pressing contact with the turntable top, and stable disc drive can be achieved.

Second Embodiment

Next, the configuration of a spindle motor according to a second embodiment of the present invention is described by way ofFIG. 7.FIG. 7is a side view of a spindle motor M2of this example, and the right half of the drawing is shown as a cross-section. InFIG. 7, parts that are the same as parts inFIG. 1are given identical reference numerals, and description of these parts is omitted.

The spindle motor M2of this example differs from the spindle motor M1ofFIG. 1primarily in the shapes of the rotor case, disc guide, and cylindrical member.

The rotor case51of this example is formed into a cap shape from a magnetic plate, and has a cylinder part51a, which is formed into a cylinder with the same axis as the rotary shaft22, and a upper face51b. which is a plane. The rotary shaft22is fixed to a burring51c, which is provided in the center of the upper face51bof the rotor case51.

The disc guide53of this example is formed in an annular shape from a hard resin; a plurality of guide claws53care provided at the outer circumference thereof at equal intervals in the rotational direction, and a plurality of protrusions53dare provided on the bottom face. Furthermore, the inner diameter of the disc guide53serves as a through-opening. The disc guide53is unified with the rotor case51by way of inserting and thermal compression bonding the protrusions53din the plurality of through-holes provided in the upper face51bof the rotor case51.

The clamping magnet27is disposed in the through-opening portion of the disc guide53and is directly disposed on the upper face51bof the rotor case51. Thus, the rotor case51serves as a back yoke for the clamping magnet27, and with the spindle motor M2of this example, the yoke plate26inFIG. 1is unnecessary.

As shown inFIG. 8, the upper part of the outer circumference58aof the cylindrical member58of this example, which is parallel with the axial direction, is the inclined face58b, which is curved, the outer diameter thereof gradually decreasing in the upward direction. Furthermore, the bottom face of the cylindrical member58is the flat first bottom face58c.

As shown inFIG. 7, the structure is such that the outer diameter of the outer circumference58aof the cylindrical member58is larger than the inner diameter of the clamping magnet27, and the first bottom face58cof the cylindrical member58faces the top face of the clamping magnet27in the axial direction. Thus, with the spindle motor M2of this example, the same as with the spindle motor M1, even if the clamping magnet27were to detach and rise from the turntable, the clamping magnet27would be stopped by abutting against the first bottom face58cof the cylindrical member58.

Next, a disc clamping mechanism that uses the spindle motor M2of this example is described usingFIG. 9.FIG. 9(a) shows the state before an optical disc is held, andFIG. 9(b) shows the state of the optical disc being held.

In FIG,9, parts that are the same as parts inFIG. 3are given identical reference numerals, and description of these parts is omitted. When the optical disc40is transported to the space between the spindle motor M2and the clamper30A as shown inFIG. 9(a), the spindle motor M2is raised. Thereupon, as shown inFIG. 9(b), the guide claws53cof the disc guide53abut the inner edge of the central hole40aof the optical disc40, and the optical disc is automatically centered. Meanwhile, the clamper30A is automatically centered by way of being attracted by the clamping magnet27and the positioning hole31abeing guided along the inclined face58band the outer circumference58aof the cylindrical member58. Consequently, the disc pressing portion32of the clamper30A stably holds the optical disc40in the gap with the upper face51bof the rotor case51, and eccentricity when the optical disc40is rotated by way of driving the spindle motor M2is controlled, thus allowing suitable recording and playback of the optical disc40.

Thus, with the disc clamping mechanism of this example, the outer circumference58a, which is fitted in the positioning hole31aof the clamper30A, and the cylindrical member58, which has the first bottom face58cthat faces the clamping magnet27in the axial direction, are fixed in the upper portion of the rotary shaft22. Consequently, even if a need to change the shape of the disc guide were to arise, the clamper would be able to be positioned by the cylindrical member without changing the clamper. That is to say, clampers of the same shape can be used without relying on the shape of the disc guide on the turntable.

Next, the positional relationship among the parts in the disc clamping mechanism of this example is described in detail usingFIG. 10. With the disc clamping mechanism of this example, the first bottom face58cof the cylindrical member58faces the clamping magnet27in the axial direction with a gap H1therebetween. Furthermore, as inFIG. 10, in a state where the clamper30A presses the optical disc40in contact with the turntable top, the first bottom face58cof the cylindrical member58is positioned lower than the opposite face33of the clamper30A that faces the clamping magnet27in the axial direction. That is to say, the gap H1is established smaller than the gap H0. Consequently, according to the disc clamping mechanism of this example, even if the clamping magnet27were to detach and rise from the turntable, the clamping magnet27would be stopped by abutting against the first bottom face58cof the cylindrical member58, and would not touch the clamper30A. Thus, even if the clamping magnet27were to detach from the turntable, the clamping magnet27would not attach to the clamper30A, the optical disc40would be able to be clamped in a state in which it is in pressing contact with the turntable, and a stable disc drive can be achieved.

Furthermore, with this example, the clamping magnet27is disposed so as to be in direct contact with the upper face51bof the rotor case51, the magnetic body rotor case51serves as the back yoke, and the yoke plate26inFIG. 1is unnecessary. Accordingly, the overall spindle motor can be made to have a lower profile.

The embodiments of the present invention were described above, but the present invention is not limited to these modes of embodiment, and the present invention can be practiced with suitable changes to the various component members or the like, within the scope of the gist of the invention.

For example, in the above embodiments, the cylindrical member28,58has a through-hole, but it may also be a cap shape with a closed top face. Furthermore, in the above embodiments, an inclined face28b,58bis provided in the upper portion of the outer circumference28a,58aof the cylindrical member28,58, but the inclined face28b,58bdoes not necessarily have to be provided if, for example, an inclined face, which has the same functionality, is provided in the positioning portion on the clamper side, or if a disc guide is used for clamper positioning uses. Furthermore, in the above modes of embodiment, the cylindrical member28,58is directly press-fit into the rotary shaft22, but it can also be press-fitted in the outer circumference of the barring part21c,51cof the rotor case or in the outer circumference of the upright portion23aof the disc guide.

Furthermore, in the above embodiments, the clamper30A that has a positioning hole31ais used, but as shown inFIG. 11, a clamper30B that has a positioning recess31bcan also be used, for example. The inner diameter of the positioning recess31bis slightly larger than the outer diameter of the outer circumference28aof the cylindrical member28. However, as inFIG. 11, with a structure that performs clamper centering by way of fitting the positioning recess31bof the clamper30B with the outer circumference28aof the cylindrical member28, slight variations in centering precision tend to occur. The reason for this is that, because there are many cases in which a clamper requires raised/recessed machining in addition to the positioning recess31bfor centering, precise control of the inner diameter dimension of the positioning recess31bfor centering is difficult, and variations in the inner diameter tends to occur. Meanwhile, variations in centering precision can be controlled with a structure wherein the clamper is centered by way of fitting the clamper positioning hole31aand the outer circumference28a,58aof the cylindrical member28,58ain the modes of embodiment above. The reason for this is that the dimensions of the positioning hole31acan be easily managed regardless of the raising/recessing on the clamper. Thus, for the disc clamping mechanism of the prevent invention, the embodiments ofFIG. 3orFIG. 9are preferred over the embodiment ofFIG. 11.

Furthermore, the disc guide23used in the first embodiment and the cylindrical member58used in the second embodiment can be combined for a configuration such as inFIG. 12toFIG. 14. In the example inFIG. 12, the gaps for the parts of the disc clamping mechanism have the following relationship:
0<H1<H0.
H1<H2, and
H1<H3.

In the example inFIG. 13, the gaps for the parts of the disc clamping mechanism have the following relationship:
0<H1<H0, and
H1=H2<H3.

In the example inFIG. 14, the gaps for the parts of the disc clamping mechanism have the following relationship:
0<H1<H0,
0<H2<H1, and
H2<H3.

In the disc clamping mechanism ofFIG. 12toFIG. 14as well, even if the clamping magnet27or the disc guide23were to rise from the turntable, the optical disc40would be clamped in a state in which it is pressed in contact with the turntable top, and stable disc driving would be possible.

This invention can be applied to a disc clamping mechanism whereby an optic disk, a magneto-optical disc or the like is held and rotated.

DESCRIPTION OF REFERENCE NUMERALS