JP2981333B2 - Optical information recording medium - Google Patents

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 center hole is formed in the center thereof. Optical information recording media (write-once, 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) and used. This drive is a device having built-in electronic components, and always generates some heat during energization. In particular, the portion of the spindle that contacts the media to rotate the media is close to the motor and hot.

On the other hand, a polycarbonate resin is generally used as a substrate material of an optical information recording medium. This polycarbonate resin has a large photoelastic constant. Immediately after a medium is mounted on a drive, a rapid rise in temperature causes an increase in birefringence, which adversely affects recording and reproduction characteristics. Further, since the temperature of the spindle portion is high, only the inner peripheral portion of the medium has a particularly high temperature, and the temperature unevenness in the plate surface causes an increase in 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, which affects not only birefringence but also surface deflection.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has been made to prevent a rapid rise in the temperature of a medium and to reduce the difference in temperature 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]

To achieve the above object, the present invention provides (1)
In an optical recording medium that irradiates a high-energy beam such as a laser and performs recording and reproduction of information, a hole is provided between the innermost periphery of a region for recording information and the innermost periphery of the substrate to penetrate the front and back of the substrate. And (2) a plurality of holes are provided between the innermost circumference of the recording area and the clamping zone at the center of the substrate. (3) In (2) above, The center axis is not perpendicular to the plate surface, but is more than 5 ° in the circumferential direction at the radial position of the substrate where the center of the hole exists.
And the deviation from the circumferential direction in the direction of the inclination is ± 45 ° or less. (4) In (3), at least one central axis of the hole is The falling direction is opposite to the circumferential direction of the substrate of the other hole. (5) In (2), the innermost circumference of the recording area of the hole and the substrate The opening ratio to the area between the central clamping zones is 3% or more, 80
% Or less. Hereinafter, a description will be given based on examples of the present invention.

FIG. 1 is a structural view for explaining an embodiment of an optical information recording medium according to the present invention. In the figure, reference numerals 1 and 2 denote a substrate, reference numerals 3 and 4 denote recording layers, reference numeral 5 denotes a hub, and reference numeral 6 denotes an adhesive. Layer, 7 is an information recording area, 8 is a clamping zone, 9 is an area between,
10 is a hole. The substrates 1 and 2 have a structure in which the recording layers 3 and 4 are adhered to each other, 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. Preferably, a plurality of holes 10 are provided, and the holes 10 are preferably arranged at positions where dynamic balance can be achieved with respect to the rotation center of the medium. The shape of the hole is preferably circular, but any shape such as elliptical, triangular, square, polygonal, etc. 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 15 of spindle 16
Diverges into the air at the hole 17 and the heat reaching the recording area 13 decreases.

FIGS. 4A, 4B, and 4C show another embodiment of the optical information recording medium according to the present invention.
8 and 19 are holes, and 20 and 21 are central axes. FIG. 2B is a sectional view taken along line AA ′ of FIG. 2A, and FIG.
It is B 'sectional drawing. The central axis 20 of the hole 18 is inclined by θ from the perpendicular to the substrate, and the central axis 21 of the hole 19 is inclined by θ ′ opposite to the perpendicular to the substrate. As a result, when the substrate rotates, an airflow is generated from the upper surface to the lower surface 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 inclination θ, θ ′ of the central axis is 5 ° or more and 70 °
The following is preferred. When the angle is 5 ° or less, the effect of generating an air flow is small, and when the angle is 70 ° or more, it is difficult to form a hole. Further, it is preferable that the deviation of the radius of the central axis where the central axis exists from the tangential direction is ± 45 ° or less. When the angle is 45 ° or more, the effect of generating an airflow decreases. The size of the hole is arbitrary as long as it falls within the area between the information recording area and the clamping zone, but it is preferable that the aperture ratio with respect to the area of this area is 3% or more and 80% or less. If it is less than 3%, the heat radiation effect and the effect of generating airflow between the upper and lower surfaces cannot be obtained, and if it is more than 80%, the rigidity of the medium is reduced.

FIG. 5 shows a time-dependent change in the temperature rise of the medium surface when the present invention is carried out. In the figure, is the bottom surface of the embodiment,
Represents the case of the upper surface of the example, represents the lower surface of the comparative example, and represents the case of the upper surface of the comparative example. The medium is 130mm double-sided bonding type, the outside temperature is 20 ℃, the drive temperature is 35 ℃,
Under the condition of the spindle temperature of 45 ° C., the temperature of the substrate surface having a radius of 30 mm was measured after inserting a medium having substantially 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 and at equal intervals in the circumferential direction. Four central axes of the holes were tilted by 20 ° in the tangential direction of the position where the holes exist, 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 increased only by 3 ° C. from the internal temperature of the drive, and the temperature difference between the upper and lower surfaces was 2 ° C. However, in the comparative example, the surface on the spindle side rose to the temperature of the spindle portion, and the temperature difference between the upper and lower surfaces also increased. 5
° C. In addition, it goes without saying that the present invention can be applied not only to the bonding type but also to the single plate type.

[0011]

As 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 transmitted from the spindle can be reduced. (2) By making the hole outside the clamping area, the effect of (1) can be obtained without affecting clamping. (3) By inclining the axis of the hole, an airflow is generated between the upper and lower surfaces, and the temperature difference between the upper and lower surfaces can be reduced.

[Brief description of the 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 illustrating 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 temporal 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)

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