JPS62167636A - Information medium disc - Google Patents

Abstract

PURPOSE:To prevent invasion of water content from a disc end face by forming an information medium layer to a region of the 1st dielectric layer except the outermost circumference and the innermost circumference and forming the 2nd dielectric layer so as to cover the entire face of the information medium layer wider than the region of the said information medium layer. CONSTITUTION:The outer circumference edge of the 1st dielectric layer 7 formed to one face of a disc base 7 is formed up to the outer circumference edge of the base 7 but not reached to the outer circumference region 11 and the inner circumference region 12 of the dielectric layer 9 of the recording medium layer 10. Further, the recording medium layer 10 is a so-called phase change type recording film, where the optical density is changed reversibly by the heat of the laser light so as to apply recording/reproduction/erasure. The 2nd dielectric layer 13 formed to the upper side of the recording medium layer 10 is formed at the same region as the 1st dielectric layer 9. The protection plate 14 of nearly the same shape as that of the disc base 7 is adhered to the disc base 7 via an adhesives 15. Since the entire circumference of the recording medium layer is sealed closely by the dielectric layer, the invasion of water content is prevented and the adhering strength of the outer circumference edge is improved.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to an information carrier disk (hereinafter simply referred to as a disk) in which an information medium layer is formed on one side of a transparent disc-shaped substrate.
It is related to.

(Prior art) Conventionally, an unrecorded recording medium layer is formed on one side of a disc-shaped transparent cutting plate, and minute holes are formed in the recording medium layer by irradiating laser light from the transparent substrate side, or Discs in which recording and reproduction are performed by forming bits with varying optical densities have been put into practical use. Furthermore, so-called erasable disks, which can be repeatedly recorded and reproduced by reversibly changing the optical density of the recording medium layer, are being put into practical use. In the case of this erasing disc, the recording medium layer is heated to above its melting point by the heat of the laser beam, and then recorded and erased by rapid cooling or slow cooling. Therefore, if a resin material is used for the disk substrate forming the recording medium layer, the disk substrate will be deformed by this heat, making it impossible to repeat recording and erasing. For this reason, a dielectric layer for preventing thermal deformation is formed between the disk substrate and the recording medium layer or between the recording medium layer and a protective layer that protects the recording medium layer.

Conventionally, various proposals have been made regarding the quality of this dielectric layer, but all have the structure shown in Figure 2.In Figure 2, l is the disk substrate, and 2 is one side of the disk substrate 1. 3 is the first dielectric layer formed on the surface of the first dielectric layer;
A recording medium layer is formed on the dielectric layer 2, on which a second dielectric 17j4 is formed, and the first dielectric layer 2, the recording medium layer 3, and the second dielectric layer are It has a structure in which a temporary layer 5 is formed to protect the layer 4. There is also an example in which a protective plate is bonded onto the second dielectric layer via an adhesive instead of the protective layer 5. In the configuration shown in FIG. 2, recording, reproduction, and erasing are performed by irradiating laser light in the direction of arrow 6.

(Problem to be solved by the invention) However, from a practical point of view, since the recording medium layer is exposed at the outer edge of the disk or the edge of the center hole,
It has the disadvantage that moisture easily penetrates and the recording medium layer is likely to deteriorate.

In addition, since it is simply laminated, there is a problem that it tends to peel off especially from the outer peripheral edge, which impairs reliability.

The present invention aims to prevent deterioration of the recording medium layer by preventing moisture from entering from the end surface of the disk, thereby obtaining a reliable disk that does not peel off.

(Means for Solving the Problems) In order to solve the above problems, the present invention is to form the recording medium layer so as not to reach the outermost and innermost peripheries of the dielectric layers formed on both sides thereof. That is, in the present invention, after forming a first dielectric layer on one surface of a disk-shaped substrate,
An information medium layer is formed in the area excluding the outermost and innermost peripheries of the dielectric layer, and a second dielectric layer is formed to cover the entire surface of the information medium layer wider than the area of this information medium layer. This is a characteristic feature.

(Function) By preventing the recording medium layer from being exposed to the edge surface of the disk as described above, it is possible to prevent the infiltration of moisture that would deteriorate the recording medium layer, thereby extending the life of the recording medium layer. At the same time, since peeling is less likely to occur, a reliable disc can be obtained.

(Example) Hereinafter, one embodiment of the present invention will be described based on the drawings.

In FIG. 1, 7 is a disk substrate, which has a center hole 8 in the center. Reference numeral 9 denotes a first dielectric layer formed on one surface of the disk substrate 7, and the outer circumferential edge of the first dielectric layer 9 is formed on the outer circumferential edge of the disk substrate 7. Reference numeral 10 denotes a recording medium layer, which is formed so as not to reach the outer peripheral region 11 and inner peripheral region 12 of the first dielectric layer 9 . The recording medium layer 10 is a so-called phase-change type recording film that performs recording, reproduction, and erasing by reversibly changing the optical density using the heat of laser light. A second dielectric layer 13 is formed above the recording medium layer 10, and is formed in the same area as the first dielectric layer 9. 14 is approximately the same as the disk board 7.
It is a shaped protective plate and is bonded to the disk substrate 7 via an adhesive 15.

In the configuration shown in FIG. 1, recording, reproduction, and erasing are performed by irradiating laser light from the direction of arrow 16. Since the dielectric layer has a structure in which the dielectric layer is densely packed, by using a material that does not easily allow moisture to pass through, it is possible to prevent moisture from penetrating, thereby preventing deterioration of the recording medium layer.

Furthermore, by adopting the configuration as shown in FIG. 1, the number of layers formed in the outer circumferential area 11 and inner circumferential area 12 of the dielectric layer is smaller than in the area of the recording medium layer IO, which makes it particularly difficult for peeling to occur. This makes it possible to improve the bonding strength of the outer peripheral area, which is easy to bond. As a method for selectively forming the recording medium layer in this way, the recording medium layer is generally formed by a vapor deposition method, a sputtering method, etc., but there is also a method that can be easily formed by masking during this formation. It is.

Although this embodiment has been described with respect to a disk in which a recording medium layer is formed on only one side, a similar structure can be applied to a double-sided disk in which recording medium layers are formed on both sides.

Furthermore, although the phase change type erasing disk has been described, it can also be applied to a magneto-optical disk in which recording, reproduction, and erasing are performed using the heat and magnetic field of a laser beam.

(Effects of the Invention) The present invention can prevent the intrusion of moisture, which is the main cause of deterioration of the recording medium layer, by sealing the entire circumference of the recording medium layer with a dielectric layer, and also prevents the intrusion of moisture, which is the main cause of deterioration of the recording medium layer, and also prevents the intrusion of moisture, which is the main cause of deterioration of the recording medium layer. Is it possible to improve the bonding strength of the edges and make it reliable and practical? This is something that can earn you a lot of money.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an information carrier disk according to an embodiment of the present invention, and FIG. 2 is a sectional view of a conventional information carrier disk. 7... Disk substrate, 9... First dielectric layer, IO
...Recording medium layer, 13...Second dielectric layer. Fig. 1 7... r chair 7 substrate 9... with 1 layer (ki layer 1O-4ii #t!<1.? 13... multi 2qKi persimmon layer Fig. 2

Claims (1)

[Claims] After forming the first dielectric layer on one surface of the disk-shaped substrate, an information medium layer is formed in the area excluding the outermost and innermost peripheries of the first dielectric layer, and from the area of this information medium layer An information carrier disk characterized in that a second dielectric layer is formed to broadly cover the entire surface of the information carrier layer.