JPS5935092B2 - Information recording media manufacturing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for manufacturing an information recording medium, in which a large number of recesses (for example, signal pits) constituting information tracks are provided on a base, and a light reflective layer is formed on the surface of the base. In particular, it provides an apparatus suitable for the production of video disc recording discs, which are provided with audio and/or video information tracks and whose recorded information is read (played) by an optical system. It is.

Conventionally, the base of this type of recording disk is obtained by press-molding a thermoplastic resin such as vinyl chloride using a metal stamper.

At this time, the signal pit of the stamper is transferred to the substrate side,
A spiral information track is constructed. In order to optically read this information using a laser beam, a metal reflective film is uniformly deposited from the right angle direction over the entire surface of the base including the signal pit, and the light reflected from the reflective film on the bottom of the signal pit and The intensity of the light caused by interference due to the phase difference with the reflected light from the reflective film on the surface of the substrate other than the signal pits is converted into an output signal, and reading is performed using this signal. In the present invention, instead of such a reading method, reading is performed using a difference in reflectance. a shielding plate in which a substantially fan-shaped cutout is formed, which is arranged as shown in FIG. 0<tanθ≦d/a (θ: angle with respect to the surface, d: depth of the recess, a width of the recess).
and a vapor deposition source arranged to selectively reach the substrate, and the information recording medium is characterized in that the light reflecting layer is not substantially formed on at least the bottom surface of the recessed part. This relates to manufacturing equipment.

With this device, it is possible to efficiently manufacture readable information recording media by utilizing the difference in reflectance, and S/
The N ratio can also be improved. Next, an embodiment in which the present invention is applied to a video disk recording disk will be described with reference to the drawings.

1 to 3 show a base 1 obtained by press-molding a damper by a conventionally known method.

This base 1 is made of thermoplastic resin, and has signal pits 2 on its surface with a length of about 1.3 μm and a depth of about 0.4 μm.
It is arranged in a spiral shape. The drawing shows three rows of pits 2.
Each column is arranged at a pitch of 2 to 3 microns and constitutes an information track. Next, a method for forming a light reflecting layer on such a substrate 1 will be described with reference to FIGS. 4 to 10.

As shown in FIG. 4, Al is vapor-deposited onto the substrate 1 at an angle θ at right angles to the length direction of the pits 2 as shown by arrows 3 and 4 using an apparatus to be described later. In this case, Al reaches the lowermost part of the right wall surface 6 of the pit 2 while its adhesion is regulated by the edge 5 of the base 1 facing the pit 2. As a result, Al is deposited on the right wall surface 6 above the bottom, but not on the left wall surface 7 and bottom surface 8 of the pit 2 due to the masking effect of the edge 5. Furthermore, Al is uniformly attached to the upper surface 9 of the base 1 as well. Therefore, as shown in FIGS. 5 and 6, substantially no Al is deposited on the left wall surface 7 and bottom surface 8 of the pit 2, but an Al deposited layer 10 is formed over the right wall surface 6 and top surface 9 thereof.

Note that since the front wall surface 11 and rear wall surface 12 of the pit 2 are somewhat rounded, a small amount of Al adheres to these surfaces as well, but these are omitted in the drawing. In FIG. 4, there is a tan
Since there is a relationship θ-d/a, in order for A1 to not be deposited on the bottom surface 8 of the pit 2 and Al to be deposited on the top surface 9, the relationship 0Tanθ≦d/a must hold. be.

As shown in FIG. 4, when Al is deposited to the bottom of the right wall surface 6 of the pit 2, when a=0.8μ, T
Since anθ=1/2, it is sufficient to perform the vapor deposition at θ+26 degrees.

In this way, at least in the video disc recording disk 13 in which Al is not deposited on the bottom surface 8 of the pit 2 and the Al deposited layer 10 is formed on the top surface 9, the reading laser is used as shown by the dashed line in FIG. Spot 14 of light is bit 2
Laser light is irradiated so that the holes are formed sequentially along the length direction.

At this time, since there is a vapor deposited layer 10 on the upper surface 9 of the base 1, the reflectance between the reflected light of the laser beam 15 incident on this surface and the reflected light from the bottom surface 8 of the pit 2 (almost none) are different. Therefore, since the output signal obtained when the spot 14 is formed on the top surface 9 and the output signal obtained when the spot 14 is formed on the bottom surface 8 are different, the signal recorded by the pit 2 cannot be optically reproduced. I can do it. Note that there is also a vapor deposited layer on the right wall surface 6 of the pit 2, but since this layer is almost perpendicular to K, it does not substantially affect the output. Further, although some amount of Al partially adheres to the bottom surface 8, this does not substantially affect the amount of reflection by the bottom surface 8. Note that it is desirable that the difference in reflectance between the top surface 9 and the bottom surface 8 be set to a level that allows a good S/N ratio.

Next, the manufacturing apparatus will be explained with reference to FIGS. 8 to 10.

First, to explain the overall configuration of the device, a bottom plate 1 is connected to the bottom of a glass Persian 16 via a gasket 17.
A rotary shaft 21 of a motor 20 is inserted into the center of the motor 8 in a sealed state with a seal 19 .

The rotating shaft 21 is connected to a rotating table 22, and the above-mentioned base 1 is fixed on this rotating table. In addition, leads 25 and 2 of the vapor deposition source 24 are connected to the bottom plate 18 via an insulating bushing 23.
6 is fixed and taken out to the outside. The vapor deposition source 24 is
Arm parts 25a and 26a provided integrally with both leads 25 and 26
Tungsten heater 2 connected with screws 27 and 28 between
The central part of this heater is wound in a spiral shape, and the vapor deposition source 24 is placed in a housing space 30 shaped like an inverted triangular pyramid. A shielding plate 31 is disposed close to the top of the base 1, and as shown in FIG. 8, this shielding plate 31 has a fan-shaped cutout 32 formed therein so that Al can pass therethrough. What is the difference between the shielding plate 31 and the base 1?
They should be circles of the same shape, and their centers should match. To operate this manufacturing device, first evacuate the inside of the Persian 16 through the exhaust pipe 33 connected to the bottom plate 18, and then
A voltage is applied between both leads 25 and 26 to cause the heater 29 to generate heat, thereby causing Al to flow from the Al vapor deposition source 24 to the surrounding area.
scatter in a radial manner. Before this, the substrate 1 is rotated at a rate of 1 revolution per second by the motor 20, and Al is deposited for about 5 minutes during this rotation. Al scattered from the vapor deposition source 24 travels radially in the direction of the arrow 34, passes through the cutout 32 of the shielding plate 31, and reaches the base 1 in a state approximately perpendicular to the length direction of each pit 2 of the base 1. do. The direction of vapor deposition of A1 is determined by the angle θ as described above. As a result, as described above, Al is deposited on the substrate 1 from an oblique direction at an angle θ, approximately perpendicular to the pit 2, so that Al is not deposited on the bottom surface of the pit 2, and on the top surface 9 of the substrate 1. An Al vapor deposition layer 10 is formed.

The size and shape of the cutout portion 32 of the shielding plate 31 are selected so that the direction of Al vapor deposition with respect to the length direction of each pit 2 is substantially perpendicular, and the Al vapor deposition angle with respect to the substrate 1 is approximately θ. Also, since the shielding plate 31 is present, the heater 2
It is possible to prevent the base body 1 from being thermally deformed by the heat generated by the base member 9. The state shown in FIG. 7, that is, the reproduction operation will be explained in more detail with reference to FIG. 11. In the playback device, the γth
A base body 1 shown in the figure is fixed to a rotating shaft of a motor 35. As shown in FIG.

A dust cover 37 having an opening 36 in the radial direction is disposed close to the front surface of the base body 1 . An air bearing head 39 fixed to a movable table 38 is disposed within the opening 36, and an objective lens (not shown) close to the base 1 is held in position by the air bearing. Although not shown,
In order to perform cutting in the preliminary stage of stamper production, a laser beam 41 from an Ar laser 40 is modulated by an electric shutter 42, and then a prism 43 and a lens 44 are used.
, a dichroic mirror 45, and are guided by a mirror 46 to the objective lens of the head 39 and to a predetermined position on, for example, a photoresist layer to be cut.

At this time, the base 1, for example a glass plate, is rotated and the moving table 3
By moving the photoresist layer 8 at a constant speed, the photoresist layer can be cut in a spiral manner. In addition, in order to perform reproduction as in this embodiment, the base body 1 shown in FIG. 51, 45, and 46 to guide the spot so that a spiral spot trajectory is formed in the same manner as described above on the substrate 1, and the tracking transducer 52 detects the reflected light from the surface. I can do it. Note that in order to adjust the focus of the laser beams 41 and 48, the lenses 44 and 50 may be moved. As explained above, according to this embodiment, Al is deposited approximately perpendicular to the length direction of each pit 2 and obliquely at an angle θ with respect to the substrate 1.
Although no deposited layer is substantially formed on the bottom surface 8 of each pit 2, A1 is effectively deposited on the top surface 9 of the base 1, and the reflectance of the top surface 9 and the bottom surface 8 of the pit 2 is different. Records can be manufactured efficiently.

Therefore, in this recording disk, recorded information can be reproduced using the difference in the amount of reflection (reflection intensity) rather than the phase difference of the reflected light. Furthermore, since the difference in the amount of reflection can be made clearly, the S/N ratio can be improved. Although the present invention has been described above based on one embodiment, it will be understood that further modifications can be made based on the technical idea of the present invention.

For example, the deposition angle θ may be adjusted so that no Al is deposited on the lower portion of the pit side wall surface. Further, the vapor deposition material may be any material having a good reflectance, such as a metal other than A1, and the base material may be any other material having a reflectance different from that of the vapor deposition material or a light transmitting material. Note that the present invention is also applicable to cylindrical recording bodies. As described above, in the present invention, since the deposition is performed at an angle θ to the substrate and substantially perpendicular to the length direction of the recess, a reflective layer is not substantially formed on the bottom of the recess. Regardless, a reflective layer is effectively formed on the top surface of the base, and a recording medium that reproduces recorded information by utilizing the difference in reflectance between the bottom surface of the recess and the top surface of the base can be efficiently manufactured. Further, since regions having different reflectances, that is, the bottom surface of the recess and the top surface with the light reflecting layer can be formed accurately, the S/N ratio can be improved.

[Brief explanation of the drawing]

The drawings show an embodiment in which the present invention is applied to a video disc recording disk, in which FIG. 1 is a plan view of a part of the base, FIG. 2 is a cross-sectional view taken along the line -- in FIG. 1, and FIG. Figure 1 is a sectional view taken along the - line, and Figure 4 is a cross-sectional view of Al in the state shown in Figure 3.
5 is a sectional view similar to FIG. 4 with Al deposited on it, FIG. 6 is an enlarged perspective view of a part of the substrate with Al deposited on it, and FIG. The figure is a cross-sectional view taken along the line - in FIG. 6 when the laser beam for reading is irradiated, FIG. 8 is a partial plan view when vapor deposition is performed using a shielding plate, and FIG. 9 is a partial vertical cross-sectional view of the manufacturing apparatus. FIG. 10 is a partially longitudinally sectional front view of the heater portion housing the vapor deposition source; FIG.
The figure is a schematic diagram of a writing and reading device. In addition, in the symbols used in the drawings, 1 is the base, 2
10 is the A1 vapor deposition layer, 15 is the laser beam, 24 is the pit,
29 is a tungsten heater, 31 is a shielding plate,
32 is the cutout, 39 is the air bearing head, and 47 is H.
The e-Ne laser 52 is a tracking transducer.

Claims (1)

[Claims] 1 A number of recesses constituting information tracks are provided in the base,
In an information recording medium manufacturing apparatus in which a light reflective layer is formed on the surface of the substrate, the light reflective layer is disposed close to the surface to cover the surface and spreads from near the center toward the periphery. A shielding plate in which a fan-shaped cutout is formed, and a shielding plate that extends through the cutout and is substantially perpendicular to the length direction of the recess and with respect to the surface, 0<tanθ≦d/a (θ:
an evaporation source arranged to selectively reach the constituent material of the light reflective layer to the substrate according to the relationship between the angle with respect to the surface, d: depth of the recess, and a: width of the recess; An apparatus for manufacturing an information recording medium, characterized in that the light reflecting layer is not substantially formed on at least the bottom surface of the recess.