JPH01298549A - Double sides optical disk medium - Google Patents

Abstract

PURPOSE:To absorb the volumetric change by the temp. rise of the gas in an internal space by thin films and to prevent the deformation of the disk by disposing the film surface sides of two pieces of the optical disk pieces opposite to each other, holding an inner circumferential spacer and outer circumferential spacer in place between said pieces, fixing the disk pieces by an adhesive agent, providing a through-hole to at least either of the optical disk pieces and the outer circumferential spacer and sealing the through-hole with the thin films having excellent flexibility. CONSTITUTION:The double sided optical disk medium is constituted by including the optical disk pieces 1, 2, the inner circumferential spacer 3, the outer circumferential spacer 4, and the thin films 5, 6. The thin film 5 on the outer circumferential side and the thin film 6 on the inner circumferential side are for absorbing the volumetric change by the temp. change in the internal space 7. The thin films are, therefore, required to have the properties of high flexibility and high resistance to corrosion. Synthetic resins such as polyvinylidene chloride and metallic films consisting of gold, platinum, etc., are desirable as the material of said thin films. The higher reliability is obtd. if the thin films 5, 6 are fixed to the disk in the state of substituting the gas in the space 7 with an inert gas such as, for example, argon.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a double-sided optical disc medium, and particularly to a double-sided optical disc medium in which optical disc pieces are bonded together to increase the storage capacity of a computer mass storage medium.

[Conventional technology]

As shown in Fig. 3, a conventional double-sided optical disc medium consists of two optical disc pieces 1' and 2', each having a recording film formed on one side of a PC (polycarbonate) substrate, with the recording surfaces facing each other, with the inner and outer peripheries placed between them. The inner spacer 3' and the outer spacer 4', each having a width in a numerical order in part and having a thickness of about 0.5 mm, are sandwiched and fixed with adhesive so that the membrane surfaces do not touch each other.

By bonding the optical disc pieces 1' and 2' together in this way, approximately twice the storage capacity is realized.

However, if the inner circumferential spacer 3' and outer circumferential spacer 4' are brought into close contact with each other over the entire circumference, the inner space surrounded by the pair of optical disc pieces 1' and 2' and the inner circumferential spacer 3 and outer circumferential spacer 4 is The space becomes sealed.

Therefore, when the temperature rises or falls during use, the optical disk pieces 1', 2' are damaged at the exact midpoint between the inner circumferential spacer 3' and the outer circumferential spacer 4' of the double-sided disk medium due to the expansion and contraction of the internal gas. A warp is produced in which the displacement of is maximum. If there is warpage, it becomes impossible to write information to or read information from the optical disk medium.

Therefore, in conventional double-sided optical disk media, the inner spacer 3
' and a part of the outer circumferential spacer 4' are usually provided with ventilation holes 10.
11, and the effect of warping is eliminated by the temperature difference through these ventilation holes 10° and 11.

[Problem to be solved by the invention]

However, in the conventional double-sided optical disk medium described above, when considering the reliability of the recording film, the deterioration of the recording film is mainly caused by corrosion, and is greatly affected by temperature and humidity. In addition to the direct entry and exit of corrosive gases such as oxygen through the pores, they are also directly affected by external humidity, which has the disadvantage that their lifespan is significantly shortened by the external environment.

[Means to solve the problem]

The double-sided disk medium of the present invention has two optical disk pieces with their film surfaces facing each other and fixed with an adhesive with an inner circumferential spacer and an outer circumferential spacer in between, and a through hole is provided in at least one of the optical disk piece and the outer circumferential spacer. The outside of the hole is sealed with a highly flexible thin film, and the internal space is sealed.

Furthermore, the gas in the internal space is replaced with an inert gas.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIGS. 1(a) and 1(b) are a perspective view and a sectional view taken along the line A-A, showing an embodiment of the present invention.

The double-sided optical disc medium shown in FIGS. 1(a) and 1(b) includes optical disc pieces 1 and 2, an inner spacer 3, an outer spacer 4, and thin films 5 and 6.

The optical disk pieces 1 and 2 are provided with inner circumferential spacers 3 of several cylinders in width and around 0.5 in thickness so that the recording film surfaces face each other.
and the outer circumferential spacer 4 are sandwiched between them and fixed with adhesive.

A through hole 9 is provided in a part of the outer circumferential spacer 4, and the end portion is made of, for example, a metal foil having excellent flexibility and gas barrier properties so as to enclose the through hole 9.

It is sealed with a thin film 5 such as a thin film of synthetic resin, and this thin film 5
It is fixed only at the periphery, with small wrinkles near the center and a slight sag.

Alternatively, the area between the part where the hub is attached and the area where the recording film is formed may be used.

That is, after molding the substrate of at least one of the optical disc pieces 1 and 2, a small hole is made in a portion included in the above region, and this hole is used as a through hole 8, and a thin film 6 is fixed to the substrate surface so as to enclose it. ing.

When the two optical disc pieces 1 and 2 are pasted together with the inner circumferential spacer 3 and the outer circumferential spacer 4 in between as described above, an internal space surrounded by the optical disk pieces 1 and 2 and the inner circumferential spacer 3 and the outer circumferential spacer 4 is created. 7 is created, but this internal space 7
The volume V is the outer diameter d of the inner spacer 3 and the outer diameter d of the outer spacer 4.
When the inner diameter D1 is the spacer thickness t, the following equation (1) is obtained.

Further, the temperature of the gas in the internal space 7 may vary from room temperature to, for example, △
When the temperature changes to T'C plus, the volume of the gas in the internal space 7 tends to increase by about - times its original volume, assuming the pressure is constant.

Conversely, when the temperature changes from room temperature to minus
to” - produces a two-fold volume reduction.

The thin film 5 on the outer circumferential side and the thin film 6 on the inner circumferential side are for absorbing volume changes due to temperature changes in the internal space 7. Only the peripheral portions of the thin films 5 and 6 are fixed to the outer edge or the inner disk surface so as to enclose the through holes 8.9.

Furthermore, the thin films 5 and 6 are wrinkled near the center, and at the same time are slightly slackened from the ends of the optical disc pieces 1 and 2 at the outer periphery and from the surfaces of the optical disc pieces 1 and 2 at the inner periphery. That is, when the temperature rises, the thin films 5 and 6
The wrinkles are stretched, and when the temperature drops, the slack is removed.

Therefore, it is desirable that the thin film be highly flexible and resistant to corrosion. The thin film material is preferably a synthetic resin such as polyvinylidene chloride, or a metal thin film such as gold or platinum.

Further, the gas in the internal space 7 may be, for example, argon.

Reliability can be further improved by fixing the thin films 5 and 6 while replacing the gas with an inert gas.

When the operating temperature range is narrow, only one of the thin films 5 and 6 described above may be used, and the length in the circumferential direction is also determined based on the operating temperature range, and is not particularly limited. Note that the maximum displacement amount of the thin film on the inner circumferential side is the height of the hub mentioned above, and the maximum displacement of the thin film on the outer circumferential side is naturally limited within the range of allowance dimensions when housed in a cartridge.

〔Effect of the invention〕

The double-sided optical disc medium of the present invention has a through hole instead of a ventilation hole, so that a thin film fixed to the outside absorbs the change in volume due to a rise in the temperature of the gas in the internal space, and at the same time, the gas in the internal space is replaced with an inert gas. This has the effect of achieving high reliability.

[Brief explanation of the drawing]

FIGS. 1(a) and 1(b) are a perspective view and a sectional view taken along line AA' of an embodiment of the present invention, and FIG. 2 is a perspective view of a conventional example. 1.2.1'2'... group optical disc piece, 3°3'.
...Inner spacer, 4.4'...Outer spacer, 5,6...Thin film, 7...Inner space, 8,9... Through hole, 10, 11...
Ventilation hole D...Inner diameter, d...Outer diameter, t.
·····thickness. Agent Patent Attorney Uchihara Construction 11 yen] (O)

Claims (1)

[Claims] A pair of optical disk pieces provided with their film surfaces facing each other, an inner spacer that supports the optical disk piece on the inner side, an outer spacer that supports the optical disk piece on the outer side, and a pair of the optical disk pieces and the outer spacer. 1. A double-sided optical disc medium comprising: a flexible thin film for sealing the outside of at least one through hole so as to hermetically seal an internal space.