JPH01109550A - Optical disk substrate - Google Patents

Abstract

PURPOSE:To prevent the damage of an optical head and optical disk substrate by contact of both and to stabilize the traveling of the optical head by forming thin carbon films having a prescribed film thickness on the optical head traveling surface side of glass substrates. CONSTITUTION:The thin carbon films 2 having 10-100nm film thickness are formed on the optical head traveling faces of the glass substrates 1 and the light beam projected from the head traveling face transmit is focused through the thin films 2 and the substrates 1 to recording materials 3. The lubricity of the optical disk is enhanced by this constitution without impairing the transparency of the light beam and the damaging of both the optical head and the optical disk is obviated even if both come into contact with each other. The traveling of the optical head is thus stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical disc substrate particularly suitable for a disc using a floating optical head.

[Conventional technology]

In an optical disk device, an optical head performs focus servo and tracking servo while maintaining a distance of about 1 mm above the optical disk medium, moves an objective lens, and irradiates a light beam to a desired information recording position to record and reproduce information. conduct.

FIG. 2 shows a conventional optical head. That is, the light from the semiconductor laser 21 is converted into parallel light by the collimating lens 23 after passing through the wavelength plate 22 . Next, this parallel light passes through the beam splitter 24 and enters the objective lens 2.
After the light is focused at 5, it is irradiated onto the optical disc 26. Then, the light reflected by the optical disk 26 is transmitted to the objective lens 25.
After passing through the beam splitter 24 , the light is reflected by the beam splitter 24 and enters the light receiving element 27 .

The incident light is converted into an electrical signal by the light receiving element 27 and then separated into a reproduction signal and a servo signal.

Based on this servo signal, a signal for driving the lens is generated and applied to the lens driving means 28.

As this lens driving means 28, a two-dimensional voice coil motor is usually used to move the objective lens 25 in the tracking and focusing directions.

[Problem that the invention seeks to solve]

In this way, the conventional optical head has various devices mounted in the housing 29. Therefore, the weight of the optical head becomes large, making it difficult to reduce the weight. As a result, it takes time to move the optical head to a desired track. Furthermore, the running state of the optical head becomes unstable. Therefore, there is an urgent need to develop a small and light optical head.

In order to improve these drawbacks, a floating head that uses dynamic pressure from disk rotation has been proposed (Japanese Patent Laid-Open No. 6
(See Publication No. 2-113, etc.).

According to this floating head, the floating gap between the optical disk and the optical head is maintained constant, so a focus servo mechanism for focusing light on the recording surface of the optical disk is not necessary or can be simplified. Ru. Therefore, it is possible to reduce the weight of the floating head.

However, because the floating gap is micro-onder, it is not reliable against collisions while driving, and ``no concrete implementation means have yet been shown.''

Therefore, the present invention aims to eliminate and eliminate such drawbacks of the prior art.
By forming a specific thin film on the head running surface side of the substrate, even if the head and disk collide, they will not be damaged and the head will be improved. The purpose is to stabilize driving.

[Means for solving problems]

In order to achieve the object, the optical disk substrate of the present invention is characterized in that a thin carbon film having a thickness of 10 to 1100 nm is formed on the optical head running surface side of the substrate.

Here, glass can be used as the material of the substrate.

[Effect]

A carbon thin film with a thickness of 10 to 1100 nm has sufficient optical transmittance and mechanically sufficient lubricity. Therefore, when light is irradiated onto the optical disc substrate, the light is not attenuated by this carbon thin film. Further, even if the optical head comes into contact with the substrate, the friction between the two is small and the optical head or the optical disk substrate will not be damaged.

〔Example〕

Hereinafter, the features of the present invention will be specifically explained using examples with reference to the drawings.

FIG. 1 is a sectional view showing an optical disc according to an embodiment of the present invention.

The optical disc of this embodiment includes a glass substrate 1.

If the glass substrate 1 is used as it is, even if the smoothness of the head running surface is sufficient, the lubricity is insufficient. Therefore, in the unlikely event of a contact accident between the glass substrate l and the optical head,
Alternatively, the adsorption phenomenon with the head becomes a problem.

Therefore, in this embodiment, a thin carbon film 2 is formed on the head running surface of the glass substrate 1 by vapor deposition or sputtering.
is formed. When carbon is formed into a thin film in this manner, the carbon has a graphite structure, a diamond structure, or an amorphous structure.

The thickness of this carbon thin film 2 must be maintained within a range of 10 to 1100 nm. If this film thickness is less than 10 nm, the lubricity of the optical disc will be poor and stable running will not be achieved. On the other hand, if the film thickness is 1100n or more, the light transmittance will be insufficient and the signal-to-noise ratio (S/N) during reproduction will be low.
) deteriorates.

A light beam irradiated from the head running surface passes through the carbon thin film 2 and the glass substrate 1 and focuses on the recording material 3. In the example shown in Figure 1, two substrates with these configurations are pasted back to back to create a hollow state, creating a so-called air sandwich structure. In the case of such an air sandwich structure, since the recording material 3 is not exposed to the outside air, there is no deterioration of the recording material 3 due to oxidation, dirt adhesion, etc.
The life of the optical disc can be extended.

On the other hand, it is preferable that the material of the head slider facing the optical disk is determined with particular consideration to the state of contact with the disk surface. It is preferable to make the head slider from amorphous carbon from the viewpoint of not damaging the disk surface and also preventing the optical rad slider itself from being damaged. Moreover, a plastic substrate can also be used instead of the glass substrate 1 constituting the optical disc. In this case, since it can be easily processed into a substrate, it is also possible to use an optical disk on which a pre-group for tracking is formed.

〔Effect of the invention〕

As described above, according to the present invention, since a carbon thin film with a thickness of 10 to 1100 nm is formed on the surface of the substrate, the lubricity of the optical disc can be improved without impairing the light transmittance. Therefore, even if the optical head were to come into contact with the optical disk, neither would be damaged.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an optical disc according to an embodiment of the present invention. On the other hand, FIG. 2 shows a conventional optical head. 1: Glass substrate 2: Carbon thin film 3: Recording material patent applicant Fuji Xerox Co., Ltd. Agent
Masu Kobori (2 idiots) Flute 1 Diagram 2

Claims (1)

[Scope of Claims] 1. An optical disk substrate characterized in that a thin carbon film having a film thickness of 10 to 100 nm is formed on the optical head running surface side of the substrate. 2. An optical disc substrate characterized in that the substrate material according to claim 1 is glass.