JP2000076762A - Device for mounting optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remarkably reduce the vibration amplitude of the end part of a disk against the forced vibration from the outside by mounting an optical recording medium with the intervention of a damping member on a flange-stated receiving surface provided on a spindle hub and holding the optical recording medium with pressurization by a clamp ring from the last end surface. SOLUTION: An annular protrusion 4 is provided on the pressurizing surface of the clamp ring 22, and a top spacer ring 2 is interposed between an optical disk 10" on the upermost stage and the annular protrusion 4, and a bottom spacer ring 3 is also interposed between an annular damping member 1 provided on the flange-stated optical disk recording surface 20A of the spindle hub 20 and an optical disk 10' on the lowermost stage. The center diameter ϕC of the annular protrusion 4 of the clamp ring 22 is manufactured so as to be ϕC=(ϕA+ϕB)/2. Since the pressurizing force of a fastening screw for the clamp is arranged so as not to act direct to the optical disk 10" on the uppermost stage by the operation of the top spacer 2, the uniform tightening force is applied to the optical disk to suppress the warp.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording / reproducing apparatus for an optical recording medium, and more particularly to an apparatus for mounting a plurality of optical recording media on which measures are taken to attenuate externally applied vibrations. The present invention relates to an apparatus for mounting a plurality of optical recording media, in which a head is approached to or in contact with a recording layer of an optical recording medium to perform recording / reproducing, and measures against vibration attenuation of an optical recording medium recording / reproducing apparatus.

[0002]

2. Description of the Related Art An optical recording medium (hereinafter referred to as an optical disk) on which information can be written and / or read by a laser has a larger recording capacity and a random access than conventional recording media. It is widely used as a recording medium in fields such as audio software, computer software, game software, and electronic publishing.

[0003] Further, with the development of computer technology, the capacity of recording devices has been steadily increasing. Conventional optical disks include a read-only type (ROM), a rewritable type (RAM), and a write-once type. In these media, an optical head is provided on the side opposite to the recording surface of the optical disk substrate. The so-called substrate surface incidence method is adopted in which the reading light or the recording light emitted from the substrate passes through the substrate and reaches the recording surface. Since the optical head is provided with an objective lens movable in the direction of the focal axis by an actuator so that these lights are focused on the recording surface, the distance between the optical head and the disk is usually about 1 mm.

On the other hand, in recent years, as a recording / reproducing apparatus having a large capacity and high-speed access, an apparatus using an existing various optical disk as a hard disk has been proposed (Nikkei Mechanical 1998.05, No.524, P.58, etc.). reference). That is, a plurality of optical disks are built in, an optical head is provided to face each recording surface, and recording / reproduction is performed by so-called film surface incidence without a substrate. In the conventional substrate incidence method, the numerical aperture of the objective lens could not be increased because the aberration of the light spot increased due to the inclination of the substrate and errors in the thickness of the substrate. By increasing the numerical aperture and reducing the light spot,
Larger capacity of optical disk and high-speed access like hard disk became possible.

FIG. 6 is an example of a conventional recording / reproducing apparatus, which is a partially omitted sectional view of the entire apparatus. Six double-sided recording type optical discs 10 are alternately arranged with a spacer ring 21 interposed on the outer periphery of a spindle hub 20. , And pressed and held by the clamp ring 22 from the final end face.
Note that a resin substrate is used for the substrate of the optical disk 10 as in the case of a conventional optical disk. The spindle hub 20 is rotatably supported on the spindle shaft 25 via bearings 23A and 23B integrally with the optical disc 10.

The optical head 40 is supported by a head support arm 41 so as to sandwich each optical disk 10. The laser light is transmitted to the optical head 40 up to the head end by an optical fiber (not shown). A micromirror is incorporated at the tip of the head, and the transmitted laser light is turned by the mirror toward the medium. By controlling the direction of the micro mirror, servo for recording and reproduction is performed. The support arm 41 is supported by a cylindrical arm support section 42. Further, the arm support portion 42 includes bearings 43A, 43B.
The drive means 45 is rotatably supported by a head rotating shaft 44 via a drive arm 45 and is provided on a side opposite to the support arm 41 so that the optical head 40 can reciprocate in the radial direction on the disk surface of the optical disk 10. And it is designed to swing and rotate at high speed.

The distance between the optical disk 10 and the optical head 40 differs depending on the optical head, but is usually set to 3 μm or less. In the case of a flying head in which a lens, a reflecting mirror, or an optical fiber is installed on a flying slider, in order to maintain this distance, the spring pressure of the support arm 41 that presses the slider against the disk and the buoyancy required for flying are obtained. The area and shape of the slider section can be set. Further, a contact type head in which a slider portion and a disk surface are partially in contact has been proposed.

When recording information sent from the outside, each head detects address information (physical position on the substrate) based on a pre-recorded preformat and records the information on the opposing optical disk. Record information in layers.
The information may be recorded by using only one head or both heads simultaneously. When reading information recorded on a disc, the position of the recorded information is searched for and read by a head. At this time, each head may independently perform servo adjustment on recorded information so as to maximize the reproduction signal intensity. Even when the head position when the rotation of the disk is stopped is in contact with the disk as in the so-called CSS method, it is close to or in contact with the disk only during rotation of the disk as in the dynamic loading method,
When the disk is stopped, it may be sufficiently away from the disk. In addition, in this type of recording / reproducing apparatus, it is considered that the rotation speed of the spindle hub 20 becomes a high-speed rotation of, for example, 4500 rpm to 5400 rpm, and further 7200 rpm with an increase in data transfer rate along with an increase in storage capacity.

[0009]

According to the study of the present inventors, it has been found that the following problems occur when an optical disk is used in the recording / reproducing apparatus. That is, in the conventional optical disk, the distance between the optical head and the substrate is usually 1 m.
On the other hand, when an optical disk is used in the recording / reproducing apparatus, the distance between the optical head and the substrate is extremely short and is usually 3 μm or less, so that characteristics completely different from those of the conventional optical disk are required. .

First, a countermeasure against vibration of the disk substrate when vibration is applied to the recording / reproducing apparatus from the outside or the like. Secondly, since the substrate of the optical disk is made of resin, when a plurality of optical disks are mounted on the spindle hub, if the pressing load by the clamp ring is irregularly applied, deformation such as warpage of the optical disk is likely to occur. First, a first measure against vibration will be described. When an external vibration is applied to the above-described recording / reproducing apparatus, the substrate itself vibrates in accordance with the applied frequency, but the substrate vibrates violently when the applied frequency substantially matches the natural frequency of the substrate itself. . The frequency at this time is generally called a resonance frequency. The substrate has a disk shape and the inner peripheral portion of the optical disk is fixed by the spindle hub and the clamp ring. Therefore, the amplitude width at the end of the outer peripheral portion of the substrate becomes large. Also, the larger the vibration applied from the outside, that is, the larger the acceleration, the larger the vibration amplitude.

When the vibration amplitude at this resonance frequency is large, the distance between the head and the substrate is short, so that
Due to the vibration of the substrate, the relative position between the head and the substrate slightly shifts, or the relative angle slightly changes. For this reason, the servo signal is adversely affected and the track is deviated during recording / reproducing, or a problem is caused in the recording / reproducing of the signal and the signal quality is reduced. In the case of a flying slider head, the flying height of the head becomes unstable, and the head collides with the disk, making it impossible to record or reproduce the collision part.
The head is damaged and recording / reproduction cannot be performed at all.

More specifically, when the disk is forcedly vibrated so that the maximum value of acceleration is ± 0.5 G (G represents acceleration; 1 G is 9.8 / S ² ) at the resonance frequency of the disk, The amplitude of vibration is ± 0.25 mm (that is, 0.5
mm), it is said that the above-mentioned problem occurs when a substrate is used. Even if the recording / reproducing apparatus is stationary, the substrate vibrates at a natural frequency due to the resistance of air when the disk rotates at high speed inside. The self-excited vibration of the substrate is known as flutter. If the amplitude of the vibration exceeds 0.5 μm (that is, 1.0 μm in full amplitude), the above-described disturbance of the servo signal and the quality of the recording / reproducing signal will occur. The problem of degradation occurs. As described above, in the recording / reproducing apparatus of the above-mentioned method, it is required that the vibration of the substrate of the optical disk is extremely small as compared with the related art.

The following means can be considered to suppress the disk vibration amplitude due to external forced vibration. (1) Improve the rigidity of the disk substrate. In general, the rigidity of a disk substrate is determined by the cube elasticity (Young's modulus: E) of the disk material and the cube (t ³ ) of the thickness (t) of the disk substrate.
It is proportional to the product of That is, the bending elastic modulus of the material used for the disk substrate is increased, or the thickness of the disk substrate is increased. (2) A material having a large vibration damping property, that is, a material having a large loss coefficient η, is used as a material for the disk substrate.

However, if resin is used for the disk substrate of (1), it is difficult to remarkably increase the flexural modulus. Since the rigidity is proportional to the cube of the thickness t, the vibration amplitude can be easily reduced by increasing the thickness. However, increasing the thickness is not preferable because the recording / reproducing apparatus becomes large. This is particularly noticeable in a recording / reproducing apparatus in which several disks are stacked. Further, it is difficult to form pits on an optical disk by using aluminum, glass, or the like having a bending elastic modulus several times or more than that of resin. further,
It is preferable to use a material having a large loss coefficient η as the disk substrate material in (2) in terms of suppressing vibration. However, if η is too large, E becomes small,
Conversely, the vibration amplitude increases. A resin material having a large E and a large η is limited and is not preferable in forming an optical recording medium.

Next, the second problem of warpage when a plurality of optical disks are mounted will be described. In the optical disk recording / reproducing apparatus of the present invention, the spindle assembly 30 supported by the bearings 23A and 23B rotates at high speed by a DC motor with the spindle shaft 25 as a fixed center axis. In the spindle assembly 30, a plurality of optical disks 10 and spacer rings 21 are alternately stacked on the spindle hub 20, and can be rotated via bearings 23A and 23B. The fixing of the optical disk 10 to the spindle hub 20 is supported by a pressing load by a screw or a pressing load by a rivet when the optical disk 10 is mounted by the clamp ring 22.

However, when the above-mentioned pressing load is applied to the inner peripheral portion of the optical disk irregularly, the optical disk 10 is deformed such as warpage. When deformation occurs, the relative position of the head and the substrate slightly shifts, as in the first problem,
The relative angle changes slightly. For this reason, the servo signal is adversely affected and the track is deviated during recording / reproduction, or a problem occurs in the recording / reproduction of the signal, thereby deteriorating the signal quality. In the case of a flying slider head, the flying height of the head becomes unstable, and the head collides with the disk, making it impossible to perform recording / reproduction at the collision portion, or the head is damaged and recording / reproduction cannot be performed at all. Further, when deformation occurs, when forced vibration is applied from the outside, the vibration amplitude may be significantly increased.

The present invention solves these problems and provides an optical disc mounting device suitable for use in such a recording / reproducing device. That is, the present inventors have found that, when a specific mounting device is employed in a mounting device for a plurality of optical discs in a recording / reproducing device, the vibration amplitude at the end of the disc can be significantly reduced with respect to forced vibration from the outside. Was found.
Furthermore, it has been found that, when a plurality of optical disks are mounted on a spindle hub via a spacer ring, the use of a specific member can reduce the warpage of the mounted optical disk.

Here, the points that led to the invention of the apparatus for suppressing the propagation of vibration to the optical disk 10 and the vibration amplitude at the end of the optical disk of the present invention will be described. The spindle shaft 25 is fitted and supported on a spindle motor board 24, and the motor board 24 is fastened to a chassis 52 with screws. The optical disk 10 is alternately stacked on the spindle hub 20 and the spacer ring 21 as described above, but the outer diameter of the spindle hub 20 is smaller than the inner diameter of the optical disk 10 and the spacer ring 21 for convenience of mounting. . Generally, the fitting gap is 10 to 50 μm. The forced vibration applied to the recording / reproducing device 50 from the outside is propagated to the spindle shaft 25 through the chassis 52. The vibration propagated to the spindle shaft is propagated to the spindle assembly 30 and transmitted from the flange-shaped receiving surface portion of the spindle hub 20 to the bottom disk 10 '.

FIG. 4 shows a simple model of the vibration propagation in this case.
Shown in When the vibration energy 51 applied from the outside propagates to the optical disk 10, it can be represented by a series of a spring constant K and a damping C. Here, K and C are characteristics possessed by the resin optical disk substrate. Black circles in the figure (●
(Mark) indicates the spacer ring 21. The spacer ring is generally formed of aluminum, stainless steel, or the like. These materials have a much higher Young's modulus than resin, and a lower damping, so that the K of the spacer ring is low.
And C were ignored. That is, the vibration energy applied to the recording / reproducing device 50 of the present invention depends on K and C unique to the optical disc substrate.
From the bottom disk 10 'to the top disk 10 "
The vibration is attenuated toward.

The present inventors use the vibration damping member 1 for attenuating vibration in the flange portion of the spindle hub 20 on which the bottom disk is mounted, thereby significantly reducing the vibration energy transmitted to a plurality of optical disks. Therefore, we found a device that can easily suppress the vibration amplitude at the end of the optical disk. Further, by providing the spacer element 21 with the spring element K and the damping element C, it is possible to attenuate the vibration. Further, by using the mounting apparatus, the range of selection of the material of the optical disk substrate is widened, which is very advantageous in manufacturing the optical disk.

[0021]

SUMMARY OF THE INVENTION An object of the present invention is to provide an apparatus for mounting an optical recording medium which solves the above-mentioned problems. The gist of the present invention is to provide a plurality of optical recording media on the outer periphery of a spindle hub and a spacer. In an optical recording medium recording / reproducing apparatus which is sequentially stacked and mounted via a ring, the optical recording medium is mounted via a vibration-damping member on a flange-shaped receiving surface provided on the spindle hub, and a clamp ring is formed from the final end surface thereof. Is a device for mounting an optical recording medium, which holds the optical recording medium under pressure.

The vibration damping material is annular, 25 ° C., 100 Hz
An optical recording medium mounting device having a loss coefficient μ of 0.020 or more in the above. The vibration damping member is annular, and its outer dimensions are smaller than the outer dimensions of the flange-shaped receiving surface of the spindle hub, its thickness is 0.05 to 2.0 mm, and its flexural modulus E is 2.1 GPa. This is the optical recording medium mounting apparatus described above.

Further, there is provided an optical recording medium mounting apparatus in which an annular projection is provided on the pressing surface of the clamp ring, and the optical recording medium is pressed and held by the clamp ring with a top spacer ring interposed from the final end surface.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical recording medium mounting apparatus according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a partially omitted sectional view showing an embodiment of the present invention, and FIG. 2 is an enlarged partially omitted sectional view showing an example of a spindle assembly formed in the same manner as the spindle assembly incorporated in FIG. FIG. 3 and FIG.
FIG. 4 is a partially omitted enlarged sectional view showing another example of a spindle assembly incorporated therein, FIG. 4 is a model diagram of vibration propagation through a spindle assembly to a plurality of optical disks, and FIG. 5 is used in the present invention. FIG. 6 is an explanatory view showing an example of a layer configuration of an optical disc, and FIG. 6 is a cross-sectional view of a conventional example in which the entire apparatus is partially omitted.

First, in the embodiment shown in FIGS. 1 to 3, the spindle assembly 30 of the optical recording medium recording / reproducing apparatus 50 includes a spindle hub 20, a spacer ring 21, six optical disks 10, a clamp ring 22, a spindle shaft 25 and the like. It is composed of The spindle hub 20 is cylindrical, and a lower end portion 20A of the spindle hub forms a flange-shaped optical disc receiving surface. On the outer periphery of the spindle hub 20,
Six optical disks 10 and spacer rings 21 are alternately stacked. Further, a disc-shaped clamp ring 22 for pressing and holding the uppermost surfaces of the six optical disks is provided at the upper end of the spindle hub 20. The spindle hub 20 includes a spindle shaft 25 rotatably supported via bearings 23A and 23B.

Further, in FIG. 1, twelve optical heads 40 provided opposite to the front and back surfaces of the optical disk 10 include:
Each optical disk 10 is supported by a head support arm 41 so as to sandwich it. Laser light is transmitted to the optical head 40 to the head end by an optical fiber (not shown). A micromirror is incorporated at the tip of the head, and the transmitted laser light is turned by the mirror toward the medium. By controlling the direction of the micro mirror, servo for recording and reproduction is performed. The support arm 41 is supported by a cylindrical arm support section 42. Further, the arm support portion 42 is rotatably supported by the head rotating shaft 44 via bearings 43A and 43B. The arm support section 42 is provided with a driving means 45 on the side opposite to the support arm 41 so that the optical head 40 can reciprocate along the disk surface of the optical disk 10 in the radial direction.
Is provided, and is driven to swing and rotate at high speed.

The lower end of the spindle hub 20 is
A flange-shaped optical disk receiving surface 20A is provided, and an annular vibration damping member 1 is interposed between the upper surface of the flange-shaped optical disk receiving surface 20A and the surface where the lowermost optical disk 10 'is in contact. . The vibration characteristic of the annular vibration damping member 1 is 2
The loss coefficient η at 5 ° C. and 100 Hz is 0.020 or more, the thickness is 0.05 to 2.0 mm, and the flexural modulus E is
Is 2.1 GPa or more. The outer dimension of the annular vibration damping member is set to be smaller than the outer dimension φB of the flange-shaped optical disc receiving surface 20A of the spindle hub 20 (see FIG. 2).

In the embodiment shown in FIG. 3, the clamp ring 22 is provided with an annular projection 4 on its pressing surface to press the upper surface of the uppermost optical disk 10 "of the six stacked optical disks. Along with the top optical disk 1
Top spacer ring 2 between 0 "and annular projection 4
Is interposed. An annular vibration damping member 1 provided on a flange-shaped optical disk receiving surface 20A of the spindle hub 20
The bottom spacer ring 3 is also interposed between the optical disk 10 'and the lowermost optical disk 10'. The outer dimensions of the top spacer ring 2 and the bottom spacer ring 3 are the spacer rings 21 used when laminating a plurality of optical disks.
The dimensions are the same as the external dimensions. Further clamp ring 2
The center diameter φC of the second annular projection 4 is φC = (φA + φB)
/ 2. Here, φA represents the outer diameter of a portion of the cylindrical spindle hub 20 into which the optical disk is inserted, and φB represents the outer diameter of the flange-shaped optical disk receiving surface 20A of the spindle hub 20. A concave groove 5 is formed in an annular shape on the surface of the clamp ring 22 into which the screw is inserted.
By forming the concave groove 5, the pressing force acts uniformly on the top spacer ring 2 when pressing and tightening the clamp ring.

The clamp ring 22 is provided with an annular projection 4 on a pressing surface thereof, and the pressing force of the fastening screw of the clamp ring 22 does not directly act on the uppermost optical disc 10 ″ due to the action of the top spacer 2. As a result, an equal tightening force is applied to the optical disc to suppress the warpage of the optical disc, and the vibration damping member 1 provided on the upper surface of the optical disc receiving surface 20A of the spindle hub 20 and the lowermost stage. By providing a bottom spacer between the optical disks 10 ', the warpage of the optical disk can be suppressed, and the top and bottom spacer rings are made of aluminum, stainless steel or the like by machining.

The above contents will be described in more detail.
As shown in FIGS. 1 to 3, the spindle shaft 25 is fitted and supported on the spindle motor board 24 and the motor board 2
4 is fastened to the chassis 52 with screws. The optical disc 10 is alternately stacked on a cylindrical spindle hub 20 with spacer rings 21. The outer dimensions of the spindle hub 20 are different from the optical disc 10 and the spacer 2 for convenience of mounting.
1, usually smaller than 10-100
It is a fitting gap of μm. Stacked optical disc 1
Numeral 0 is fixed to a spindle hub 20 by a clamp ring 22, and is rotated at high speed via a bearing 23 by a spindle motor composed of a magnetic circuit formed by a magnet 27 and a coil winding 26. The number of rotations is determined by the switching speed of the current flowing through the coil winding. Note that a DC motor is usually used as this type of motor.

As the vibration source propagating to the optical disk 10, the vibration caused by the rotation of the spindle motor, the movement caused by the movement of the optical head 40, the vibration applied to the recording / reproducing device 50 from the outside, and the like can be considered. The vibration is propagated to the spindle assembly 30 through the spindle shaft 25,
The light is transmitted from the flange-shaped optical disk receiving surface 20A of the spindle hub 20 to the bottom disk 10 '. Experiments have also confirmed that, by interposing the annular vibration damping member 1 on the flange-shaped optical disk receiving surface 20A, it is possible to significantly suppress the vibration caused by the vibration at the end of the optical disk 10.

The annular vibration damping member used in the present invention has two members.
It is desirable that the loss coefficient η at 5 ° C. and 100 Hz is 0.020 or more, and the thickness is 0.05 to 2.0 mm.
Therefore, it is required that the flexural modulus E is not less than 2.1 GPa and the outer dimensions of the annular vibration damping member are smaller than the outer dimensions of the flange-shaped optical disk receiving surface of the spindle hub.

The above-mentioned loss coefficient η represents an index of the vibration damping performance of the applied vibration energy. The larger the loss coefficient is, the larger the damping effect, that is, the vibration damping ability is.
For measurement of loss coefficient of various materials, see "JIS G 0602"
Is described in detail in the test method for vibration damping characteristics. The frequency analysis can be performed by the half-width method by performing the frequency analysis using the cantilever method, which is one of the methods.

As the vibration damping member used in the present invention, a rubber-based material, a polymer material or a composite material in which a polymer material and a filler such as carbon fiber are combined, a Mn-Cu-based alloy, and a metal and a polymer material are used. Combined constrained or non-constrained damping steel plates can be considered. However, natural rubber, butyl rubber, chloroprene rubber, nitrile rubber, urethane rubber,
Silicon rubber, fluorine rubber, and the like are easy to process and have a large loss coefficient of 0.1 or more, but are not suitable because the flexural modulus is very small. This is because when the optical disk is pressed and clamped by the clamp ring, a large distortion occurs,
Further, since the permanent set due to compression is as large as 10% or more, it is not suitable for this use. Mn-Cu based alloy and damping steel sheet
Although the loss coefficient is 0.02 or more, it is not preferable because it is expensive and it is difficult to form a ring with high precision.

The annular vibration damping member used in the present invention is preferably a polymer material or a composite material with a polymer material. Specific examples of the polymer material include a liquid crystal polymer, polyacetal, and polypropylene. Examples of the composite material include, in addition to the above-mentioned materials obtained by compounding a filler such as glass fiber and carbon fiber, modified polyphenylene ether (m
There is also a composite material in which potassium titanate fibers are added using (PPE) as a base material. Among the above materials, a liquid crystal polymer, m-PPE, and a potassium titanate fiber reinforced composite material are suitable because the bending elastic modulus is 2.1 GPa or more even though the loss coefficient is as large as 0.02 or more. The annular vibration damping member 1 can be manufactured by injection molding, machining, or the like using the above-described materials.

The thickness of the vibration damping member 1 is preferably as thick as it can be said from the viewpoint of the vibration damping ability, but if it is too thick, the spindle assembly 30 becomes too large. Therefore, the thickness is suitably 0.05 to 2.0 mm. If the outer dimension of the damping member 1 is too large than the outer dimension φB of the optical disk receiving surface 20A of the spindle hub 20, the stress applied to the surface of the damping member 1 when the optical disk is pressed and held by the clamp ring 22 will be unbalanced. Then, the bottom optical disk or the like is warped. Therefore, the outer dimensions of the vibration damping member 1 are preferably smaller by about 0.05 to 0.2 mm than the outer dimensions φB of the optical disk receiving surface 20A of the spindle hub.

According to the above-described configuration of the present invention, an information recording medium provided with a recording / reproducing head at a distance of 3.0 μm or less with respect to a recording surface provided on a substrate can be externally connected to a recording / reproducing apparatus. When the vibration is applied, the substrate itself vibrates at the natural frequency, but the vibration amplitude can be suppressed. That is, when the relative position of the head and the substrate is slightly shifted or the relative angle is slightly changed, the servo signal is adversely affected and the track is displaced during recording or reproduction, or the signal recording / reproduction itself is performed. Can be prevented from deteriorating the signal quality due to the above problem. Specifically, when the disk is forcibly excited so that the maximum value of the acceleration becomes 0.5 G at the resonance frequency of the disk, the amplitude of the disk becomes 0.25 mm (0.5% at full amplitude).
mm) or less.

The optical disk used in the present invention is not particularly limited as long as it has a writable recording layer. Specifically, it is preferable to use a magneto-optical method and a phase change method that can be repeatedly rewritten. The magneto-optical method has excellent rewriting durability, from 1 million times to 1000 times.
It can be rewritten 10,000 times. The phase change method has an advantage that the optical system can be simplified since the read signal is a modulation method of the reflected light intensity. Further, as a write-once method in which writing can be performed only once, a writing method using drilling or deformation using a dye or the like can be given. The optical disc is provided with a preformat including information that can be accessed by a head for reading and writing. More specifically, the information includes address information such as a track address and a sector address, rotation synchronization information, tracking service information, and the like. A preformat used for an existing optical disc may be used as it is.

The preformat may be provided on both sides of a double-sided recording type optical disk, or may be provided on only one side, and may be provided on at least one recording surface of the optical disk for each recording / reproducing apparatus. During disc production,
A mold including addresses and tracking information is prepared, a preformatted substrate is prepared using the mold, and a layer such as a recording layer is formed as necessary to obtain an optical disc. There are various methods for producing a substrate, such as an injection molding method, a casting molding method, a press molding method, and a method using a photocurable resin. However, the method of injection molding a thermoplastic resin into a substrate is the most preferable since the production time can be shortened most. Burnishing may be performed in order to reduce protrusions on the substrate surface. In the case of a double-sided recording type optical disk, the two disks may be bonded with an adhesive with the substrate inside. Alternatively, a substrate such as a recording layer may be formed on both surfaces as necessary after manufacturing a preformatted substrate on both surfaces simultaneously by using two molds.

FIG. 5 shows an example of the layer structure of the optical disk 10 of the present invention. Double-sided optical disc comprising lubricating layer 16 / protective layer 15 / recording layer 14 / protective layer 13 / substrate 12 / adhesive layer 11 / substrate 12 '/ protective layer 13' / recording layer 14 '/ protective layer 15' / lubricant layer 16 ' It is. The substrate is generally 0.6-
The thickness is about 1.2 mm. The recording layer is TbFeCo,
It is a magneto-optical recording film such as GdFeCo or a layer change recording film such as GeSbTe-based or AgInSbTe-based. When employing a super-resolution method or the like, it may be composed of a plurality of layers. The protective layer is generally made of SiN, TaOx, Si
A dielectric such as O ₂ and ZnS is used. For the adhesive layer, a photo-curable adhesive, a hot-melt adhesive or the like is used. Further, the protective layer 13 and the substrate 12 (the protective layer 13 'and the substrate 12')
A reflective heat dissipation layer may be provided between them.

Since the signals of the optical disk are read directly from the recording film without passing through the substrate, the optical characteristics of the substrate are not important and need not be transparent. In the case where two substrates are bonded to each other, there is not much problem even if the water absorption is large. Examples of the substrate material satisfying these conditions include resins such as an acrylic resin, a norbornene resin, and a liquid crystal polymer. For example, polymethyl methacrylate (P
MMA), ARTON (Nippon Synthetic Rubber Co., Ltd., norbornene-based ester-substituted cyclic olefin ring-opening polymer hydrogenated product), Z
EONEX (Nippon Zeon Co., Ltd., hydrogenated norbornene-based ring-opening polymer), aromatic polyester-based liquid crystal polymer and the like can be mentioned.

Polymethyl methacrylate has a low heat distortion temperature and is excellent in transferability. Since ARTON is close to the glass transition temperature and the heat deformation temperature, it is possible to achieve both transferability and shape stability during molding. ZEONEX has low water absorption and particularly good shape and dimensional stability. A plurality of different resins may be blended and used. In this case, it is not always necessary to use the above resins, and the above resin and another resin may be blended or other resins may be blended and used. Generally, when a resin is blended, cloudiness occurs depending on the combination, but as described above, the substrate of the present invention can be used because the optical characteristics are not important. Further, a single resin or a blend of a plurality of resins may be used.

Further, in the present invention, it is preferable that the substrate roughness is small to some extent. If there are irregularities on the disc,
This is because a collision with the flying head or the contact head is likely to occur. In addition, when a resin having high crystallinity is used as a substrate, fine crystals are formed on the substrate surface during molding, which causes an increase in roughness. Therefore, it is preferable to use a resin having relatively small crystals.

[0044]

Example 1 [Production of Optical Disc Substrate] A disc-shaped optical disc was produced by injection molding under the following shape and production conditions. Material; ARTON (Nippon Synthetic Rubber Co., Ltd., hydrogenated product of norbornene ester-substituted cyclic olefin ring-opening polymer) Outer diameter: φ130 mm Inner diameter: φ40 mm Thickness: 1.2 mm Mold temperature; 110 ° C Resin temperature; 320 ° C Production of Member] A vibration damping member having the following shape was produced, and the measured loss coefficient was 25 ° C., 0.05 at 100 Hz, and the Young's modulus was about 9.8 GPa. Material: Polyester liquid crystal polymer Outer diameter: φ44.8 mm Inner diameter: φ40.0 mm Thickness: 0.3 mm

[Setting of Optical Disc to Spindle Assembly] The vibration damping member produced above was set on a spindle hub as shown in FIG. Next, optical disks and spacer rings were alternately stacked, and a total of six optical disks were stacked. The outer diameter of the spacer ring at this time is φ44.8m.
m, the inner diameter is 40.0 mm, and the material is aluminum. After the uppermost optical disc was set, the clamp ring was set, six locations were fixed with M3 screws, and the screws were evenly tightened with a torque wrench so that the tightening torque at that time was 0.4 Nm. As a result of calculating the tightening force and the tightening stress of the spacer ring portion, 4000N and 1
It was calculated to be 2.5 MPa.

[Vibration test by vibrator] The spindle assembly set above was mounted on a vibrator together with a chassis as shown in FIG. The vibration was forcibly applied while detecting with an acceleration sensor such that the acceleration of the chassis base was ± 0.5 G at each frequency. A sine wave was applied to the vibrator, and the sweep frequency of the sine wave was 20 to 500 Hz. The vibration amplitude at the end of the uppermost optical disc (20 mm inside from the outer circumference) was measured in a non-contact manner using a laser displacement meter, and the resonance frequency and the maximum amplitude at the time of resonance were obtained. Resonance frequency; 150 Hz Maximum amplitude: 400 μm

[0047]

Example 2 The vibration of the end of the optical disk was measured in the same manner as in Example 1 except that the following vibration damping materials were used. [Preparation of Damping Member] A damping member having the following shape was prepared, and the measured loss coefficient was 0.07 at 25 ° C. and 100 Hz, and the Young's modulus was about 5.4 GPa. Material: Modified polyphenylene ether resin and composite of calcium titanate fiber Outer diameter: φ44.8 mm Inner diameter: φ40.0 mm Thickness: 0.5 mm [Vibration test by vibrator] Resonance frequency: 148 Hz Maximum amplitude: 350 μm

[0048]

Embodiment 3 The top spacer ring and the bottom spacer ring having the following specifications were manufactured and arranged as shown in FIG. Diameter φC of annular projection of clamp ring
Was 42.4 mm. The damping member at this time is the same as that of the first embodiment.
The same as above was used. Material: Stainless steel SUS304 Outer diameter: φ44.8 mm Inner diameter: φ40.0 mm Thickness: 1.0 mm As in the first embodiment, the clamp ring is fixed at six places with M3 screws, and the tightening torque at that time is 0.4 N · m. And tightened evenly with a torque wrench. When the warp of the end of the uppermost optical disk at this time was measured in the circumferential direction, the warp could be suppressed within 10 μm. Then φC
= 43.4 mm, the warp of the end of the uppermost optical disk was 150 μm in the circumferential direction. Further, it was confirmed by an experiment that if only the top spacer ring was removed by the above-mentioned spacer ring, the warp of the end of the optical disk was increased to 200 μm.

[0049]

COMPARATIVE EXAMPLE The vibration of the end of the optical disk was measured in the same manner as in Example 1 except that the vibration damping member was not used, and the following results were obtained. Resonant frequency: 151 Hz Maximum amplitude: 800 μm

[0050]

As described above, according to the present invention, in a device for mounting a plurality of optical disks in an optical disk recording / reproducing apparatus, the vibration amplitude at the end of the disk can be remarkably reduced with respect to forced vibration from the outside. Further, when a plurality of optical disks are mounted on the spindle hub, warpage of the optical disks can be reduced. Therefore, the relative position of the head and the substrate does not slightly shift or the relative angle does not slightly change. It is possible to prevent the signal quality from deteriorating due to a problem in itself.
In the case of a flying slider head, the flying height of the head becomes unstable and the head collides with the disk, so that the recording / reproduction of the collision part becomes impossible, or the head is damaged and the recording / reproduction cannot be performed at all. Can be prevented.

[Brief description of the drawings]

FIG. 1 is a partially omitted sectional view showing an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view, partially omitted, showing an example of a spindle assembly formed equivalently to the spindle assembly incorporated in FIG.

FIG. 3 is an enlarged sectional view showing another example of the spindle assembly incorporated in FIG. 1 with a part omitted;

FIG. 4 is a model diagram of vibration transmission through a spindle assembly to a plurality of optical disks.

FIG. 5 is an explanatory view showing an example of an optical disk configuration used in the present invention.

FIG. 6 is a cross-sectional view of a conventional example in which the entire device is partially omitted.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 damping member 2 top spacer ring 3 bottom spacer ring 4 annular projection 10 optical disk substrate 20 spindle hub 20A flange-shaped receiving surface 21 spacer ring 22 clamp ring 23 bearing 25 spindle shaft 30 spindle assembly 40 optical head 50 optical recording medium recording / reproducing apparatus

Claims (4)

[Claims] 1. An optical recording medium recording / reproducing apparatus in which a plurality of optical recording media are sequentially laminated and mounted on the outer periphery of a spindle hub with a spacer ring interposed therebetween, and a flange-shaped receiving surface provided on the spindle hub is controlled. An optical recording medium mounting device in which an optical recording medium is mounted via a vibration member, and the optical recording medium is pressed and held by a clamp ring from a final end surface thereof. 2. The vibration damping member is annular, and has a temperature of 25.degree.
2. The optical recording medium mounting device according to claim 1, wherein the loss coefficient η at Hz is 0.020 or more. 3. The damping member is annular, and its outer dimensions are smaller than the outer dimensions of the flange-shaped receiving surface of the spindle bub, its thickness is 0.05 to 2.0 mm, and its flexural modulus E is 2 The optical recording medium mounting device according to claim 1, wherein the optical recording medium has a pressure of 1 GPa or more. 4. The optical recording medium according to claim 1, wherein an annular projection is provided on a pressing surface of the clamp ring, and the optical recording medium is pressed and held by the clamp ring from the final end surface thereof via a top spacer ring. Mounting device.