JPH05189806A - Optical-information recording medium - Google Patents

Abstract

PURPOSE:To prevent that the temperature of a medium is raised suddenly. CONSTITUTION:Substrates 1, 2 have a pasted structure in such a way that recording layers 3, 4 are situated at the inside; a hub 5 is installed in the central part. Holes 10 which are passed from the surface to the rear of a medium are made. It is preferable that a plurality of holes are made as the holes 10. It is preferable that they are arranged in positions which are balanced dynamically with reference to the rotation center of the medium. It is preferable that the shape of the holes is circular, but any shape such as an oval, a triangle, a square, a polygon or the like can be used.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an optical information recording medium.

[0002]

2. Description of the Related Art A conventional optical disk substrate has a flat surface except that a central hole is formed in the central portion thereof. In addition, optical information recording media (write-once type, magneto-optical, phase change, CD,
A CD-ROM or the like is usually set in a recording / reproducing device (hereinafter referred to as a drive) for use. This drive is a device with built-in electronic components, and it always generates some heat during energization. In particular, the part of the spindle that contacts the media to rotate it is near the motor and is hot.

On the other hand, a polycarbonate resin is generally used as the substrate material of the optical information recording medium. This polycarbonate resin has a large photoelastic constant, and immediately after the medium is set as a drive, the birefringence increases due to a rapid temperature rise, which adversely affects the recording / reproducing characteristics. Furthermore, since the temperature of the spindle portion is high, only the inner peripheral portion of the medium rises in temperature, and the unevenness of the temperature in the plate surface accelerates the increase of birefringence. In addition, there is a temperature difference between the surface of the medium on the motor side and the surface on the opposite side, and not only the birefringence but also the surface run-out is affected.

[0004]

[Object] The present invention has been made in view of the above circumstances, and prevents a rapid temperature rise of a medium and reduces the temperature difference between the upper and lower surfaces of the medium so as not to deteriorate the recording / reproducing characteristics. The purpose of the present invention is to provide an optical information recording medium.

[0005]

In order to achieve the above object, the present invention provides (1)
In an optical recording medium that records and reproduces information by irradiating a high-energy beam such as a laser, a hole penetrating the front and back sides of the substrate is provided between the innermost periphery of the information recording area and the innermost periphery of the substrate. Further, (2) a plurality of the holes are provided between the innermost circumference of the recording area and the clamping zone at the center of the substrate, and (3) in the above (2), The central axis is not perpendicular to the plate surface, and is 5 ° or more toward the circumferential direction of the radial position of the substrate where the center of the hole exists, 70
The angle of inclination is less than or equal to 0 °, and the deviation of the direction of inclination from the circumferential direction is ± 45 ° or less. Further, (4) In (3), at least one of the central axes of the holes is The tilt direction is opposite to the tilt direction of the other holes in the circumferential direction of the substrate, and (5) In (2), the innermost circumference of the recording area of the hole and the substrate. Aperture ratio to the area between the central clamping zones is 3% or more, 80
% Or less. Hereinafter, description will be given based on examples of the present invention.

FIG. 1 is a block diagram for explaining an embodiment of an optical information recording medium according to the present invention. In the figure, 1, 2 are substrates, 3, 4 are recording layers, 5 is a hub, and 6 is an adhesive. Layer, 7 is an information recording area, 8 is a clamping zone, 9 is an area in between,
10 is a hole. The substrates 1 and 2 have a structure in which the recording layers 3 and 4 are laminated inside, and a hub 5 is provided at the center. In an area 9 between the information recording area 7 and the clamping zone 8, a hole 10 penetrating the upper and lower surfaces of the medium is provided. It is preferable to provide a plurality of holes 10, and it is preferable that the holes 10 are arranged at a position where a dynamic balance can be obtained with respect to the center of rotation of the medium. The shape of the hole is preferably circular, but any shape such as elliptical, triangular, quadrangular or polygonal is possible.

FIG. 2 shows a case where a conventional medium is installed in a drive. The heat 15 of the spindle 14 reaches the recording area 13 through the substrate 12. FIG. 3 shows a case where the medium of the present invention is installed in a drive. Heat of spindle 16 15
Radiates into the air at the hole 17 and the heat reaching the recording area 13 decreases.

FIGS. 4A, 4B and 4C are views showing another embodiment of the optical information recording medium according to the present invention, in which 1
8 and 19 are holes, and 20 and 21 are central axes. Figure (b) is a sectional view taken along the line A-A 'in Figure (a), and Figure (c) is taken along the line B- in Figure (a).
It is a B'sectional view. The central axis 20 of the hole 18 is inclined by θ with respect to the perpendicular to the substrate, and the central axis 21 of the hole 19 is inclined with respect to the perpendicular by the θ ′ with respect to the perpendicular to the substrate. As a result, when the substrate rotates, airflow is generated from the upper surface to the lower surface of the substrate and from the lower surface to the upper surface, and the temperature difference between the upper and lower surfaces of the medium is reduced.

The inclinations θ and θ'of the central axis are 5 ° or more and 70 °
The following are preferred. If it is 5 ° or less, the effect of generating an air flow is small, and if it is 70 ° or more, it is difficult to form holes. The deviation of the central axis from the tangential direction of the radius where the central axis exists is preferably ± 45 ° or less. When the angle is 45 ° or more, the effect of generating an air flow becomes small. The size of the hole is arbitrary as long as it is in the area between the information recording area and the clamping zone, but the aperture ratio with respect to the area of this area is preferably 3% or more and 80% or less. This is because if it is 3% or less, the heat dissipation effect and the effect of generating an air flow between the upper and lower surfaces cannot be obtained, and if it is 80% or more, the rigidity of the medium is lowered.

FIG. 5 shows the change over time in the temperature rise of the medium surface when the present invention is carried out. In the figure, is the lower surface of the embodiment,
Shows the case of the example upper surface, shows the case of the comparative example lower surface, and shows the case of the comparative example upper surface. The medium is a 130mm double-sided bonded type, the outside temperature is 20 ° C, the inside temperature of the drive is 35 ° C,
Under the condition that the spindle temperature was 45 ° C., the temperature of the substrate surface having a radius of 30 mm was measured after inserting the medium, which was almost at the same temperature as the outside air, into the drive. The medium was provided with eight circular holes (radius 3 mm) at a radius of 25 mm at equal intervals in the circumferential direction. Regarding the central axes of the holes, four were tilted by 20 ° in the tangential direction of the position where the holes were present, and the rest were tilted by 20 ° in the opposite direction. A similar test was performed using a conventional medium for comparison. The medium temperature of the present invention was only 3 ° C. higher than the internal temperature of the drive, and the temperature difference between the upper and lower surfaces was also 2 ° C., but in the comparative example, the surface on the spindle side increased to the temperature of the spindle portion, and the temperature difference between the upper and lower surfaces was also increased. 5
It was ℃. The present invention can be applied not only to the bonded type but also to a single plate type.

[0011]

As is apparent from the above description, the present invention has the following effects. (1) By providing a hole between the information recording area and the innermost circumference of the substrate, heat transferred from the spindle can be reduced. (2) By providing the hole outside the clamping area, the effect of (1) can be obtained without affecting the clamping. (3) By tilting the axis of the hole, an airflow can be generated between the upper and lower surfaces, and the temperature difference between the upper and lower surfaces can be reduced.

[Brief description of drawings]

FIG. 1 is a configuration diagram for explaining an embodiment of an optical information recording medium according to the present invention.

FIG. 2 is a diagram showing a case where a conventional medium is installed in a drive.

FIG. 3 is a diagram showing a case where the medium of the present invention is installed in a drive.

FIG. 4 is a diagram showing another embodiment of the optical information recording medium according to the present invention.

FIG. 5 is a diagram showing a time-dependent change in temperature rise of a medium surface.

[Explanation of symbols]

1, 2 ... Substrate, 3, 4 ... Recording layer, 5 ... Hub, 6 ... Adhesive layer,
7 ... Information recording area, 8 ... Clamping zone, 9 ... Area, 10 ... Hole.

Claims (5)

[Claims] 1. An optical recording medium for recording and reproducing information by irradiating a high-energy beam such as a laser, and penetrates the front and back surfaces of the substrate between the innermost periphery of a region for recording information and the innermost periphery of the substrate. An optical information recording medium having a hole formed therein. 2. The optical information recording medium according to claim 1, wherein a plurality of the holes are provided between the innermost circumference of the recording area and the clamping zone at the center of the substrate. 3. The central axis of the hole is not perpendicular to the plate surface, and is inclined at an angle of 5 ° or more and 70 ° or less toward the circumferential direction of the radial position of the substrate where the center of the hole exists. 3. The optical information recording medium according to claim 2, wherein the deviation of the tilt direction from the circumferential direction is ± 45 ° or less. 4. The light according to claim 3, wherein at least one central axis of the holes is tilted in a direction opposite to a tilt direction of the other holes in the circumferential direction of the substrate. Information recording medium. 5. The aperture ratio with respect to the area between the innermost circumference of the recording area of the hole and the clamping zone at the center of the substrate is 3%.
The optical information recording medium according to claim 2, wherein the content is 80% or less.