JPS6381667A - Optical disk - Google Patents

Abstract

PURPOSE:To eliminate the occurrence of an eccentricity caused by fitting and to obtain a small and thin optical disk with high precision by bonding and assembling a hub disk and a disk mainbody by bringing the prescribed tapered surfaces into close contact. CONSTITUTION:Two single-side optical disks 52 are adhered through a spacer 53 to form a both-face optical disk 54. In the one-sided optical disk 52 the hub disk 58 is fitted to the disk mainbody 51. At the time of assembling, the tapered recessed surface 62 of the disk mainbody 51 is abutted on the tapered projecting surface 75 of the hub disk. By holding a peel surface 61 had the upper surfaces of the hub disk 58 in a parallel state, they are pressed and bonded. Consequently, there is gap of fitting at the time of assembling, whereby the occurrence of eccentricity can be prevented, and the small and thin optical disk with high precision can be formed.

Description

Detailed Description of the Invention [Object of the Invention 2] (Field of Industrial Application) The present invention relates to an optical disc suitable for making an optical disc device thinner.

(Prior Art) Recently, information processing using light has been widely put into practical use, and optical disk devices using this have also been significantly improved.

Although FIG. 7 shows a schematic configuration of a double-sided optical disc (1) as a recording medium, the dimensional proportions and actual proportions of each part are different. A double-sided optical disc (1) is a single-sided optical disc (2
), (2) are bonded together via a spacer (3). A single-sided optical disc (2) is made of, for example, a thin disc-shaped disc with a central hole (4) made of transparent polycarbonate resin, and has a signal surface (6) on the back surface (5) of which is formed with irregularities of groups and pits. ) The disk member (7) includes a disk body (9) on which a reflective film (8) made of, for example, tellurium carbon film is adhered. Then, the detection light (L3) is projected from the peel surface αυ, which is the surface α1, and the optical disc (1) is rotated for use.

The rotation mechanism for rotating this spindle αe, which has a tapered part α9 at its tip, is inserted into the center hole (4) for centering, and the entire body is supported by a support αη, and a pressing device (not shown) is applied from above. It is designed so that it can be pressed and rotated while being held between the support body αη.

However, the above-mentioned rotation mechanism has the disadvantage that the pressing device is large and expensive, and that the entire optical disk device ends up being large.

In order to avoid the above-mentioned disadvantages, an optical disk device as shown in FIG. 8 has been considered. That is, the hub disk (21) is adhered to the disk body (9) to form a single-sided optical disk 4, t7jJ, and these are adhered on the back side to form a double-sided optical disk (2). This knob disc 121) consists of a 7-rank part @, a boss part (c), an adsorbed part (b) made of a steel plate glued to the outer surface, and a centering vase. It is inserted into the center hole (4) of the disc body (9) and attached by gluing the flange component and the peel surface αυ. The rotating mechanism has a centering bottle (5) protruding from the flat end surface, and further has a centering bottle (5) protruding from the flat end surface (1).
) is embedded with an adsorbent made of a magnet to form a spindle device. And the centering bottle punishment is the centering hole (
(a) and align the optical disk (1) and the spindle device, more precisely, align the rotation center of the signal and the rotation center of the spindle device, and then insert the optical disk (1) into the end surface (c). In addition to being supported, rotational force is transmitted by the frictional force due to the adsorption force between the adsorbent (to) and the adsorbed portion Q4.

As mentioned above, since the rotational torque is transmitted by the frictional force caused by the adsorption force, there is no need for a pressing device in the center hole method shown in FIG. The inconvenience will be resolved.

However, compared to the former center hole method, this hub method is inferior in centering accuracy because the centering of the hub disk 12υ and the disk member (7) is involved. That is, since there is a gap for fitting between the boss part (end) and the center hole (4), there is a disadvantage that the centering error becomes large by this amount.

Further, as an optical problem, since the hub disk Cη and the peel surface tiυ are adhered to each other, there is a disadvantage that distortion occurs due to differences in thermal expansion or hygroscopicity between the two, resulting in deterioration of optical characteristics.

Furthermore, the disk member (7) is manufactured by injection molding, and in this case, a spool for flowing resin is formed in the portion that will become the center hole (4). In FIG. 9, the mold (31
), (32) an annular cavity (33
), the resin (35) flows through the spool (34) to form the material (7 (L)) of the disc member (7). It is formed by an annular die (37), and the die (37) forms a part of the inner surface of the center hole (4) with a side surface (39) having a step (38).

Then, when the resin (35) is injected and the temperature drops to a predetermined temperature, the first
As shown in Figure 0, the punch (36) rises and at the same time the die (37) also rises to release the resin (35) in the spool (34).
is separated and the disc material (7α) is taken out. However, since the die (37) separates from the portion (40) during cooling, the cooling rate is significantly different from that of other portions, which causes distortion and deteriorates optical characteristics.

To avoid this, when the die (37) rises, the side surface (39)
) and keep the part near it, and also draw this part with the broken line (41
), attempts were made to form the resin (35) to a sufficient size, but this did not significantly impede the inflow of the resin (35)9.
The current situation is that the result is worse, and the above-mentioned inconvenience is unavoidable.

(Problems to be Solved by the Invention) As described above, an optical disk provided with a hub disk has a thin rotating mechanism, and the entire optical disk device can be configured to be smaller and thinner than before.

However, since the center hole of the disk body and the hub portion of the hub disk fit together, the center of the centering hole of the hub disk is necessarily offset from the center of the center hole of the disk body due to the fitting gap. However, there was a problem in that the eccentricity was larger as a result than in conventional optical disks that did not use a hub disk. Furthermore, since the peel surface of the disk body and the 7-rank portion of the hub disk are bonded together, there is a disadvantage that distortion occurs due to differences in thermal expansion and hygroscopicity, resulting in deterioration of optical characteristics. Furthermore, the cross-sectional shape of the center hole of the disk body has the disadvantage that distortion occurs during injection molding, impairing optical characteristics.

The present invention has been made to eliminate the above-mentioned disadvantages, and it is possible to reduce the size and thickness of an optical disk device by attaching a hub disk to the disk body, and also to avoid an increase in eccentricity due to the use of the hub disk.

It is an object of the present invention to provide an optical disc that prevents damage from occurring and has excellent optical characteristics.

[Structure of the invention]

(Means and effects for solving the problems) When assembling the disk body and the hub disk, the present invention forms a tapered concave surface in the center hole of one disk body, and forms a tapered convex surface in the boss portion of the other hub disk. In an optical disk in which both tapered surfaces are formed and assembled together by centering the two, a fitting gap is not required and an increase in eccentricity is prevented.

By forming the opening of the center hole into a tapered concave surface, we are able to equalize the cooling rate without inhibiting the inflow of resin, improve optical characteristics, and also improve the bonding position between the hub disk and the disk body. This is intended to prevent deterioration of optical characteristics by allowing the selection of the desired values.

(Examples) Hereinafter, details of the present invention will be explained using examples shown in FIGS. 1 to 6.

The gt diagram is a cross-sectional front view of the first embodiment, and similarly to the conventional example, a single-sided optical disk (52) is attached to a spacer (52).
3) to form a double-sided optical disc (
54).

The single-sided optical disc (52) is constructed by attaching a hub disc (58) to a disc body (51) consisting of a disc member (56) and a reflective film (57). The disc member (56) is made of a thin disc member molded from polycarbonate resin, and has a central hole (60) in the center, which is concentric with the center hole and has a diameter on the peel surface (61) side. A tapered concave surface (62) is provided having a large end.

In addition, unevenness consisting of groups or pits is formed on the back surface, forming a signal surface (63).◇This signal surface (63) is coated with a reflective film (57) made of a tellurium carbon film. There is. Tapered concave surface (62) mentioned above
is that axis #! (66) is formed to coincide with the rotation center of the signal. The hub disk (58) includes a 7-rank part (71), a boss part (72), and an adsorbed part (73), where the adsorbed part (73) is made of a steel plate and the other parts are made of polycarbonate resin. ing. The 7th rank part (71) faces the peel surface (61) in parallel,
The outer side is formed flat, and a thin steel plate is glued to it to form the attracted part (73). Also, the boss part (72)
has a tapered convex surface (62) corresponding to the above-mentioned concave tapered surface (62).
75) is formed. Also, this tapered convex surface (75)
A centering hole (76) is drilled through the center line concentrically with the center axis of the center line.

Next, the hub disk (58) and the disk member (56) are assembled as shown in FIGS.
0) and the cylindrical portion (78) of the boss portion (72), or as shown in FIG.
It is bonded between the 6υ and the 7 rank part (71), or between both tapered surfaces (62) and (75) as shown in FIG.

When assembling, the flat adsorbed surface (80), which is the outer surface of the adsorbed part (73), is used as the detection surface (81).
This and the peel surface (61) may be kept parallel to each other and then pressed and bonded together. Since they are in contact with each other on their tapered surfaces, there is no fitting gap, so if the surface to be attracted (80) and the peel surface (61) are kept parallel, the hub disc (58)
) and the central axes of the central hole (60) coincide.

A single-sided optical disc (52) assembled as described above.

(52) is adhered via a spacer (53) to obtain a double-sided optical disc (54).

Next, since the rotation fk mechanism is the same as that shown in FIG. 8, the same parts are given the same numbers and detailed explanations will be omitted. The operation of the rotating mechanism is also similar, so to briefly explain, insert the centering hole (76) into the centering bottle (27) of the spindle (29), and place the attracting surface (80) on the end surface (26). When they come in contact, the attracted part (73) is attracted by the magnet body (28).
) is attracted, and the double-sided optical disk (54) is firmly fixed to the spindle (29). In this state, the double-sided optical disc (54) is rotated by the rotation of the spindle (29).

Next, the relationship between the cross-sectional shape near the center hole (60) and injection molding in this embodiment will be described with reference to FIG.

Referring to FIG. 9 and FIG. 1O, in order to prevent the occurrence of optical distortion in the center hole (4) part, it is necessary to make the cooling rate of the part (40) the same as other parts. The part of the mold that is in contact with (40) needs to have sufficient heat capacity as shown by the broken line (41), but if this is done, the inflow of resin (35) will be hindered. mentioned 0
However, in the case of this embodiment, as shown in FIG. 6, since a large tapered concave surface (62) is formed, a part (82) of the mold having a large heat capacity comes into contact with it, so that the strain in this part is significantly reduced.

Next, a second embodiment will be described with reference to FIG.

Figure 5 shows only the parts that are different from the first embodiment, such as the tapered concave surface (75) and the tapered convex surface (62).
If the tapered surfaces (75) and (62) are manufactured with high precision, it is possible to align the center lines of both tapered surfaces (75) and (62) with high precision by abutting in this way. As described above, since the optical disk of the present invention is assembled by fitting the hub disk and the disk body together on the tapered surfaces, the occurrence of eccentricity due to the fitting is prevented. In addition, by appropriately selecting the bonding area, it is possible to prevent optical properties from deteriorating due to differences in thermal expansion and hygroscopicity.Furthermore, since the cross section has a tapered concave surface, injection molding is possible. There is little distortion even when manufactured by
This has excellent effects such as preventing deterioration of optical properties.

[Brief explanation of the drawing]

FIG. 1 is a sectional front view of a first embodiment of the present invention. FIG. 2 is an enlarged sectional view of the main part of the first embodiment. FIG. 3 is an enlarged sectional view of the main part, FIG. 4 is an enlarged sectional view of the main part, FIG. 5 is an enlarged sectional view of the main part of the second embodiment of the present invention, and FIG. 6 is an enlarged sectional view of each embodiment. Injection molding explanatory diagram, No. 7
The figure is a sectional front view of a conventional example, FIG. 8 is a sectional front view of a main part of another conventional example, FIG. 9 is an explanatory diagram of injection molding in the conventional example, and FIG. 10 is an explanatory diagram of injection molding as well. . (51)...Disk body, (58)...Hub disk. (61)...Peel surface, (62)...Tapered concave surface. (75)...Tapered convex surface, (81)...Detection surface. (85)...Hub disk, (87)...Centering plane. Agent Patent Attorney Nori Ken Yudo Takehana Kikuo 2nd wJ 3rd B m4wJ Figure 5 Figure 7 Figure 8 Figure 9 Figure 10

Claims (3)

[Claims] (1) In an optical disk in which a hub disk is fixed to the center of a disk body on which unevenness corresponding to a signal is formed and is rotationally driven via the hub disk, the disk body and the hub disk are installed in the disk body. What is claimed is: 1. An optical disk, characterized in that the optical disks are concentrically connected by centering means comprising a tapered concave surface and a convex tapered surface provided on the hub disk that corresponds to the tapered concave surface. (2) The optical disk according to claim 1, wherein the hub disk has a detection surface perpendicular to the axis of the tapered convex surface. (3) The optical disk according to claim 1, wherein the hub disk has a tapered convex surface and a centering plane that is perpendicular to the axis of the tapered convex surface and abuts on the peel surface of the disk body.