JPS6329337A - Information carrier disk - Google Patents

Abstract

PURPOSE:To attain the initialization in a short time by providing a heat insulating layer composed of a material at one side of a recording film, in which the linear expansion coefficient is 1/5 or above of the linear expansion coefficient of a transparent substrate. CONSTITUTION:As a heat insulating layer, the material is used in which the linear expansion coefficient is the special value or above of the linear expansion coefficient of a transparent substrate. Polycarbonate is added to the transparent substrate 1 and a recording film 3 is made of TeOx added with 5% Ge and 10% Sn, and for heat insulating layers 9 and 10, MgO is formed by a vacuum evaporation. While turning the information carrier disk, an Ar laser beam throttling a spot diameter is radiated, the crack is hardly generated and initialization can be executed. Here, the linear expansion coefficient of the polycarbonate is about 5.6X10<-5>deg<-1> and the linear expansion coefficient of the MgO is about 1.4X10<-5>deg<-1>. The heat insulating layer 10 and a reflecting layer 5 improve C/N by using the interference of the light, the heat insulating layer 9 prevents the damage of the transparent substrate 1 due to the temperature rise of a recording film 3 at the time of recording and deleting. Thus, the whole area of the disk can be initialized in a short time.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an information carrier disk on which information is recorded, reproduced, and erased by irradiation with laser light.

Conventional technology Currently, information carrier disks called write-once type, which can record documents, image files, etc. only once, have been put into practical use as large-capacity, high-density memories, but recently it has become difficult to erase recorded information.・Development of information carrier disks called erasable type that allows re-recording is underway.

As shown in Fig. 2, this erasable information carrier disk uses an Fa-based gold metal thin film recording film, and changes the phase between an amorphous state and a crystalline state with thermal energy from laser beam irradiation. There is a phase change type information carrier disk that performs recording and erasing. This consists of a disk-shaped transparent substrate 1 having a guide groove 8, a heat insulating layer 2 such as 5i02, a Te-based recording film 3 such as TeOx Ge Sn, etc. Heat insulation layer 4. A reflective layer 5 such as a reflective layer 5 is formed in this order by a method such as vapor deposition,
A protective substrate 7 is provided thereon via an adhesive 6. When recording, the recording film is rapidly heated and cooled to an amorphous state with low reflectance by irradiating it with a laser beam with high power density that is well focused to a spot diameter of about 1 μm, forming information pits. be done. When erasing, the recording film is heated and slowly cooled by irradiating it with a laser beam shaped into an ellipse with low power density, becoming a crystalline state with high reflectance, and the information bits are erased. O In such an information carrier disk, the recording film is in an amorphous state at the time of formation. Therefore, it is necessary to convert the amorphous recording film into a crystalline state before use. Hereinafter, this process will be referred to as initialization. This initialization is generally done by the same means as when erasing recorded information, but a faster way to initialize is to irradiate it with a laser beam whose spot diameter is not very narrow. It has been proposed to treat a large area simultaneously.

Problems to be Solved by the Invention However, when initializing an information carrier disk with a heat insulating layer made of conventional SO2 using a laser beam with a spot diameter of 10 μm or more, the problem occurs due to the difference in expansion coefficient with the transparent substrate. There was a problem in that the spot diameter of the laser beam could only be increased to about 5 μm because cracks would occur in the heat insulating layer, making it unusable.

The present invention has been made in view of this point, and even when irradiated with a laser beam with a large spot diameter, no cracks occur, and
It is an object of the present invention to provide an information carrier disk that can be initialized in a short time. Means for Solving the Problems In order to solve the above problems, the present invention uses a transparent substrate with a linear expansion coefficient as a heat insulating layer. It uses a material whose linear expansion coefficient is greater than or equal to the linear expansion coefficient of

Function: The present invention has the above-described structure, and provides an information carrier disk that does not cause cranking even when initialized with a laser beam having a large spot diameter of 10 μm or more, and the entire disk can be initialized in a short time.

EXAMPLE Hereinafter, an example of the present invention will be described in detail. The information carrier disk of the present invention has the same structure as the conventional information carrier disk generally explained in FIG. 2, except for the material of the heat insulating layer, and the same numbers are given to the parts other than the heat insulating layer. . The transparent substrate 1 is made of polycarbonate, and the recording film 3 is made of Te Ox (
xzl, 1) with 10 layers of Ge54°sn added thereto, and the heat insulating layers 9 and 1° are formed by vacuum evaporation of MgO.

When this information carrier disk was rotated at 120 rpm and irradiated with Ar laser light focused to a spot diameter of about 30 μm, initialization could be performed without any cracks occurring. Here, the linear expansion coefficient of polycarbonate is approximately 5.6 x 10-5 da gl, MgQO
The coefficient of linear expansion is approximately 1,4×10 −5 dog′.

In addition, as a heat insulating layer, PbS (linear expansion coefficient 1.9x1o-
A similar effect was obtained using 5do(').

Note that the heat insulating layer 1o and the reflective layer 5 in this embodiment are for improving the C/N by utilizing light interference, and may be omitted. The heat insulating layer 9 is provided to prevent damage to the transparent substrate 1 due to temperature rise of the recording film 3 during recording and erasing, but it is recommended to use a resin material with high heat resistance as the transparent substrate 1. It can also be omitted. The present invention is effective when at least one of the heat insulating layers 9 and 10 is present.

Effects of the Invention As described above, according to the present invention, with a simple configuration, no cracks occur even when initializing with a laser beam with a large spot diameter of 10 μm or more, and the entire disk can be initialized in a short time. It is possible to provide an information carrier disk which is industrially extremely advantageous.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an information carrier disk in an embodiment of the present invention, and FIG. 2 is a sectional view of an information carrier disk in a conventional example. 1... Transparent substrate, 9, 10... Heat insulation layer,
3... Recording film, 5... Reflective layer. Name of agent: Patent attorney Toshio Nakao and 1 other person
1 Fig. 71 釆麩版 1 迩明 Answer 4 anti-Fig.

Claims (2)

[Claims] (1) A disc-shaped transparent substrate, a recording film whose phase changes due to thermal energy of laser beam irradiation, and at least one side of the recording film has a linear expansion coefficient of 1/5 or more of the linear expansion coefficient of the transparent substrate. An information carrier disk characterized in that it has a heat insulating layer made of a certain substance. (2) The transparent substrate is made of polycarbonate, acrylic resin, or epoxy resin, and the heat insulating layer is made of PbS or Mg.
The information carrier disk according to claim 1, characterized in that it is made of O and a composite compound thereof.