JPH02249151A - Optical recording medium - Google Patents

Abstract

PURPOSE:To maintain the characteristics and performance as the optical recording medium by constituting substrates and a core material in such a manner that at least either thereof is thicker by as much as the spacing therebetween at the peripheral and central part and the substrates and the core material are directly adhered and fixed. CONSTITUTION:The disk-shaped optical recording medium consists of the disk- shaped substrates 1, the disk-shaped core material 2 for preventing the deformation of the substrates and recording films 3. Each substrate 1 is made into the structure integrated with the thinner part of the intermediate part D deposited with the recording film 3 and the thicker parts of the peripheral part B and the central part C. These substrates are tightly adhered to the core material 2 at the thicker B, C parts thereof with an adhesive 4. The space generated by this structure is the difference between the thicker parts of B, C and the thinner part of D. Since the need for spacers which are heretofore used is eliminated in this way, the deformation and distortions are extremely lessened in the case of adhering the substrates 1 and the core material 2. The optical characteristics and performance of the disk optical recording medium are well maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a recording medium, and particularly to a disk-shaped optical recording medium used in an optical disk device.

[Prior Art] A disk-shaped optical recording medium used in an optical disk device or the like has a recording film on the back surface of a substrate. Since this base is not strong, a core material is housed inside and sealed to prevent it from deforming. At this time, be careful not to damage the recording film.
A gap is left between the recording film and the sixth electrode.

A laser beam for reading information recorded on the recording film passes through the substrate and reaches the recording film, and its reflected light passes back through the substrate again and is read. In conventional optical recording media of this kind, in order to create the above-mentioned gap, spacers with a thickness equal to the gap length are sandwiched between the base and core material at the periphery and center, and pressure is applied between the two to bond them together. Was.

[Problems to be Solved by the Invention] In the conventional optical recording medium described above, when the base and the core material are bonded together by applying pressure, deformation and distortion easily occur due to the presence of a spacer in between. As a result, the refractive index of the optical characteristics of the optical recording medium changes, resulting in a disadvantage that the characteristics and performance of the optical recording medium cannot be maintained.

[Means for Solving the Problems] According to the present invention, there is provided a disk-shaped substrate on which a recording film is attached to the annular intermediate portion excluding the peripheral portion and the central portion, and a disk-shaped substrate to prevent deformation of the substrate. A disk-shaped optical recording medium configured by sealing a core material with a gap left between the recording film and the core material in the peripheral portion and the center portion, wherein at least one of the substrate and the core material is sealed between the peripheral portion and the core material. An optical recording medium is obtained, which is thicker in the central portion by the amount of the gap, and configured so that the base and the core are directly and closely fixed.

[Example code] Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a partially cutaway side view showing the structure of an embodiment of a disk-shaped optical recording medium according to the present invention. In the figure, A shows the disk center line, B shows the peripheral part, C shows the center part, and D shows the middle part. The disc-shaped optical recording medium shown in this figure consists of a disc-shaped base 1, a disc-shaped core 2 for preventing deformation of the base 1, and a recording film 3. The substrate 1 has a structure including a thin part in the middle where the recording film 3 is attached, and thick parts in the peripheral part B and the central part C. This base is airtightly bonded to the core material 2 at the thick portions B and C using an adhesive 4. The void created at this time is B
, is the difference between the thick part of C and the thin part of D.

As explained above, this structure does not require the conventional spacer, so when the base 1 and core material 2 are bonded together, deformation and distortion are extremely small, and therefore, changes in the refractive index of the storage medium are extremely small. .

In this embodiment, if the same polymeric resin is used for the base 1 and the core material 2, there will be no difference in thermal expansion, and no deformation or distortion will occur.

Although in the above embodiments the base material is thicker at the outer periphery and the center, the core material, or both the base material and the core material, may instead be thicker at the outer periphery and the center region. However, in the case of both the base and heartwood, the price of the materials will be slightly higher.

[Effects of the Invention] As explained above, in the optical recording medium according to the present invention, it is not necessary to use a spacer to adhesively seal the base and the core material, so that the optical characteristics and performance of the disc optical recording medium can be improved. It has the effect of being able to be maintained and simplifying the bonding process.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway side view showing the configuration of an embodiment of the present invention. Explanation of symbols: 1 is the base, 2 is the core material, 3 is the recording film, 4 is the adhesive, A is the disk center line, B is the periphery, C is the center,
D represents the middle portion.

Claims (1)

[Claims] (1) A disk-shaped substrate having a recording film coated on an annular intermediate portion excluding the peripheral portion and the central portion, and a core material for preventing deformation of the substrate, are attached to the recording film in the peripheral portion and the central portion. In a disk-shaped optical recording medium configured by sealing a membrane and a core material with a gap left between them, at least one of the substrate and the core material is thicker in the peripheral portion and the center portion than in the middle portion by the amount of the gap. 1. An optical recording medium characterized in that the base material and the core material are directly and closely fixed to each other.