JPH03263631A - Glass substrate for optical disk - Google Patents

Abstract

PURPOSE:To prevent the protrusion of an excess UV curing resin and to obviate the generation of burrs by forming relief grooves for the UV curing resin in the vicinity of the inner peripheral edge and outer peripheral edge of a glass substrate on a disk having a center hole or either thereof. CONSTITUTION:A stamper 10 is brought into tight contact with the UV curing resin 9 on the one main surface 6a coated with the UV curing resin 9 of the glass substrate 6 and the relief grooves 19, 20 for housing the excess UV curing resin 9 when pressed by a roller are formed. The relief grooves 19, 10 are formed respectively as the toric grooves in the vicinity of the peripheral edge and outer peripheral edge of the center hole 18 of the glass substrate 6 and are concentrical. The excess UV curing resin at the time of tight contact with the stamper is, therefore, trapped by the relief grooves and the protrusion of this UV curing resin is prevented. The generation of the burrs on the inner peripheral edge and outer peripheral edge of the glass substrate is surely prevented in this way.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a glass substrate for optical disks used for various optical disks, magneto-optical disks, etc. In particular, bits are formed on the glass substrate by photopolymerization of ultraviolet curing resin. Transfer a concave-convex pattern such as a group or a group. The present invention relates to a glass substrate for optical discs manufactured by the so-called 2P method (photopolymerization method).

[Summary of the invention]

The present invention relates to a glass substrate for an optical disk used for various optical disks such as digital audio disks (so-called compact disks) and magneto-optical disks produced by the 2P method, in which a glass substrate near the inner periphery of a disk-shaped glass substrate having a center hole. By forming escape grooves for the ultraviolet curable resin near the outer periphery or in either of these areas, excess ultraviolet curable resin is prevented from spilling out, thereby eliminating the occurrence of flakes.

[Conventional technology]

When manufacturing optical discs such as digital audio discs and magneto-optical discs, pits and groups (guidance *
), etc., onto a disk substrate is to bring a stamper formed with a concavo-convex pattern into close contact with a liquid ultraviolet curable resin, and photopolymerize the ultraviolet curable resin by irradiating it with ultraviolet rays. A so-called 2P method has been proposed.

In the 2P method, a liquid ultraviolet curable resin is applied to one side of a light-transmitting disk substrate by screen printing, for example, and a stamper with a concavo-convex pattern formed on the surface is brought into close contact with the ultraviolet curable resin using a pressure roller. After that, the ultraviolet curable resin is photopolymerized and cured by irradiating ultraviolet rays from the substrate side, and the disk substrate and the cured ultraviolet curable resin layer are peeled off from the stamper to form a fine uneven pattern ( This method transfers pits and groups onto the disk substrate surface.

According to the above-mentioned 2P method, since the ultraviolet curing resin is brought into close contact with the stamper in a liquid state, it has the advantage that the fidelity of reproduction is excellent and there is almost no deterioration of the stamper. In particular, when a glass substrate is used as the disk substrate, it is very advantageous in terms of dimensional stability, heat resistance, low birefringence, etc.

[Problem to be solved by the invention]

By the way, when applying UV-curable resin to a glass substrate, if the UV-curable resin is applied to the entire surface of the substrate, there will be problems such as the resin protruding or bubbles. Screen printing is used to apply a coating using a printing pattern that is set to prevent this from occurring.

However, even if UV-curable resin is applied to the desired printing pattern in order to prevent the UV-curable resin from extruding or from forming bubbles as described above, when the stamper is in close contact with the glass substrate, excess UV-curable resin may be present inside and outside the glass substrate. It may protrude from the periphery. If this is left as it is, it will be cured by ultraviolet irradiation in the next step, and this may remain in the form of flakes. The occurrence of paris impedes recording and reproduction, especially when the disc is housed in a cartridge such as a magneto-optical disc, resulting in a decrease in yield.

The present invention was proposed in view of the above-mentioned conventional circumstances, and an object of the present invention is to provide a glass substrate for optical discs that can prevent excess ultraviolet curing resin from protruding and does not cause paris. Furthermore, it is an object of the present invention to provide a glass substrate for an optical disk that can improve the yield.

[Means to solve the problem]

In order to achieve the above-mentioned object, the glass substrate for an optical disk of the present invention is provided by forming an escape groove of ultraviolet curing resin near the inner peripheral edge and/or near the outer peripheral edge of a disk-shaped glass substrate having a center hole. It is characterized by this.

[Effect]

In the glass substrate for optical disks of the present invention, escape grooves for ultraviolet curing resin are formed near the inner peripheral edge and/or near the outer peripheral edge of the disk-shaped glass substrate having a center hole. When the stamper is brought into close contact with the resin and pressed, the excess ultraviolet curing resin flows into the relief groove and does not protrude to the inner and outer peripheries of the substrate.

〔Example〕

Hereinafter, specific examples to which the present invention is applied will be described.

The glass substrate (6) of this example is an optical disk substrate used for various optical disks, magneto-optical disks, etc.
For example, as shown in FIGS. 1 and 2, it is formed as a disk-shaped substrate having a center hole (18) in the center.

On one main surface (6a) of the glass substrate (6) to which the ultraviolet curable resin (9) is applied, a stamper (10) is brought into close contact with the ultraviolet curable resin (9) and pressed with a roller (12). Relief grooves (+9) and (20) are formed to accommodate excess ultraviolet curing resin (9). The relief grooves (19) and (20) are located on the glass substrate (6).
near the periphery of the center hole (18) and the glass substrate (6)
Annular grooves are formed near the outer periphery of the grooves, and the grooves are concentric.

The shapes of these escape grooves (19) and (20) are not particularly limited as long as they can reliably accommodate the excess ultraviolet curing resin (9). Such a suitable groove shape is, for example, a glass substrate (as shown in FIG. 3(A)).
6) groove walls (19a) on both sides of the main surface (6a);
(19b) is a relief groove (
19) and one groove wall (19a) of this relief groove (19)
or an escape groove (19) which is inclined so that the groove width becomes narrower toward the bottom as shown in FIG. 3(B), or both groove walls (19a) as shown in FIG. 3(C), (19b
) is an inclined escape groove (19) as shown in Figure 3 (B).
Further, as shown in FIG. 3(D), there may be an arcuate relief groove (19). Among them, the groove wall (+9a)
.

(19b) is tilted in Figure 3 (B) and Figure 3 (C)
The glass substrate (6) having the relief grooves (19) shown in FIG.
) can be accommodated reliably. Further, when grooving is performed, it is easier to perform grooving compared to the relief groove (19) shown in FIG. 3(A), so productivity is excellent and the life of the tool for grooving can be extended.

In addition, the relief 1 shown in FIG. 3(B) and FIG. 3(C) above
Inclination angle θ of groove walls (19a) and (19b) in (19)
The angle is preferably 20° to 80° in consideration of the ease with which the ultraviolet curable resin (9) flows into the groove.

Moreover, although the above-mentioned groove shape has been explained by taking the inner peripheral side relief groove (19) as an example, it goes without saying that it is also applied to the outer peripheral side relief groove (20). In addition, each groove shape described above is
Even if they are not formed in an annular shape, a plurality of them may be provided along the inner circumferential edge and the outer circumferential edge.

By the way, the relief grooves (19) and (20) ion-exchange Na contained in the glass substrate (6) into K in the molten salt. It is formed using a diamond cutter or the like before so-called chemical strengthening treatment. This is because when grooves are processed after chemical strengthening treatment, the glass substrate (6)
This is because the strength of the material increases, making it difficult to process, and chemical strengthening treatment increases internal stress, which can lead to breakage when mechanical processing is attempted.

The width of the escape grooves (19) and (20) is determined from the viewpoint of accommodating the excess ultraviolet curable resin (9) and ensuring a film formation area for the recording film, and is, for example, about 0.5 to 2 holes. It is preferable to do so. If the groove width is less than 0.5 mm, excess ultraviolet curing resin (9) cannot be accommodated sufficiently, and if it is larger than 2 mm, the area for forming a recording film etc. will be reduced. Also,
The depth of the relief grooves (19) and (20) is determined from the viewpoint of the strength of the glass substrate (6) and the thickness thereof,
It is desirable that the strength of the substrate (6) is not impaired. For example, the thickness of the glass substrate (6) is 1.175
In the case of mm, the depth of the groove is preferably about 0.2 to 0.3 mm. In this case, the groove depth is 0.3
- or more, the strength of the substrate (6) will be reduced.

To manufacture an optical disc using the glass substrate (6), a manufacturing apparatus shown in FIG. 4 is used.

This device continuously processes a series of steps of the 2P method, and includes a substrate supply section (1) that accommodates a glass substrate (6).
), a screen printing section (2) that applies an ultraviolet curable resin to the glass substrate (6), and a transfer section (3) that presses a stand bar onto the ultraviolet curable resin and irradiates it with ultraviolet rays to photopolymerize it.
A substrate unloading section (4) for accommodating the glass substrate (6) onto which the concavo-convex pattern has been transferred is sequentially arranged on the machine stand (5).

The substrate supply section (1) is for temporarily stocking the glass substrates (6) in the screen printing section (2) located adjacent to it, and accommodates a plurality of glass substrates (6). It is equipped with a multi-stage cartridge (7).

The screen printing section (2) is equipped with a printing stand (8) having a substrate mounting section that holds the glass substrate (6) by vacuum chucking, a mask device for screen printing, and a squeegee, and the cartridge ( A liquid ultraviolet curable resin (9) is applied to one main surface (6a) of the glass substrate (6) that has been mechanically taken out one by one by a first substrate delivery mechanism (not shown) from 7). It is applied by screen printing.

The transfer unit (3) includes a stand bar (lO) on which a concave-convex pattern of reversed bits and groups is formed, and a stand bar holder (1) that holds the stand bar (lO) and is movable in the front and back direction. along the moving direction of the stand bar holder (11).
) and a roller (12) that presses the stamper (10) onto the glass substrate (6) coated with the resin (6) and a light source (13) that irradiates ultraviolet rays to cure the ultraviolet curing resin (9) are arranged in sequence. There is.

In addition, between the screen printing section (2) and the transfer section (3), the glass substrate (6) on the printing table (8) is turned upside down, and the surface coated with the ultraviolet curing resin (9) is placed between the screen printing section (2) and the transfer section (3). Stamper (
Place the glass substrate (6) on the transfer unit (3) so as to face the transfer unit (3).
) to a second substrate transfer mechanism (not shown).

) is provided.

The substrate unloading section (4) is equipped with a multi-stage unloading cartridge (14), similar to the substrate supplying section (1) described above.
After the uneven pattern of the stamper (10) is transferred in the transfer section (3), the glass substrate (6) peeled off from the stamper (10) is sequentially transferred into the cartridge (14) by the third substrate transfer mechanism. It is designed to be accommodated in

This third substrate transfer mechanism includes a rotating arm (16) that is rotated around a rotating shaft (15), and a rotating arm (16) that is rotated around a rotating shaft (15).
16) and a suction head (17) provided at the tip of the glass substrate (6).
It has a function of adsorbing the substrate to the substrate and transferring it from the transfer section (3) to the carrying out cartridge (14) of the substrate carrying out section (4).

Manufacturing an optical disc using the above-described apparatus is performed as follows.

First, glass substrates (6) are stocked in the cartridge (7) of the substrate supply section (1) of the apparatus shown in FIG. 4 described above.

The substrate is then transferred to the printing table (8) of the screen printing section (2) by the first substrate transfer mechanism.

The glass substrate (6) on this printing table (8) is shown in Fig. 5 (
An ultraviolet curing resin (9) is immediately applied using a screen printing tool as shown in a).

The above-mentioned screen printing tool consists of a printing screen (21
) and a squeegee (22) as the main components,
After supplying the ultraviolet curing resin (9) onto the printing screen (21) stretched over the frame (23), the squeegee (22
) by sweeping the ultraviolet curing resin (9), the ultraviolet curing resin (9) is printed on the surface of the glass substrate (6) in accordance with the opening pattern.

In this example, the opening patterns of the printing screen (21) are assembled into a hexagonal pattern (21a) in a crescent shape,
The stamper (
This is to prevent exposure of the ultraviolet curing resin (9) and generation of bubbles during pressure bonding with (10).

To explain the printing screen (21) in more detail, when the running direction of the roller (12) with respect to the glass substrate (6) is in the direction of arrow A as shown in FIG. Semicircular area on the starting end side [roller used when pressing the glass substrate (6) with the stamper (10)]
In the area corresponding to the glass substrate (6) on the pressurization start end side by 12), a hexagonal pattern (21a) or a sun-moon pattern is formed along the outer periphery of the glass substrate (6). It is provided. Furthermore, a first circular pattern (21b+) and a second circular pattern (21b2) having a smaller diameter are bored along the crescent shape, avoiding the area around the center hole (18) of the glass substrate (6). has been done. In addition, a glass substrate (6) is placed in the semicircular area on the end side of the pressurization end.
A fine resin replenishment pattern (21c) is arranged in an arc shape along the center hole (18) of the resin replenishment pattern (21c), and a first circular pattern ( 2IC+) and a second circular pattern (2IC2) having a smaller diameter than this are arranged in a continuous arc shape avoiding the outer peripheral edge of the substrate (6).

Printing screen (21) having the above-mentioned opening pattern
By using the screen (21), it is possible to prevent distortion of the screen (21) and print the ultraviolet curing resin (9) stably. It becomes possible to prevent exposure.

As a result, the ultraviolet curing resin (9) is printed on the main surface (6a) of the glass substrate (6) in accordance with the open pattern provided on the screen (21).

FIG. 5(b) shows a glass substrate (6) screen-printed with an ultraviolet curing resin (9) by the above-described method.

Next, the glass substrate (6) is transferred to the transfer section (3), and the uneven pattern of the stand bar (10) is transferred thereto.

When transferring to the transfer section (3), the glass substrate (6
), and as shown in Figure 5(C), overlap it with the stand bar (10) on the stand bar holder (11) with the surface coated with the ultraviolet curing resin (9) facing downward. Ru.

Next, the glass substrate (6) stacked on the stand bar (10) is pressed by the roller (12) shown in FIG. 5(d) by moving the stand bar holder (11), and brought into close contact with the stand bar (lO). I will do it.

As a result, the ultraviolet curable resin (9) is compressed by the roller (12) and enters the fine uneven pattern of the stand bar (10) uniformly and without any gaps. In addition, at this time, escape grooves (19) and (20) for the ultraviolet curing resin are formed near the inner and outer peripheral edges of the glass substrate (6), respectively, so that the remaining ultraviolet curing resin (9) These relief grooves (
+9), flows into (20). Therefore, the ultraviolet curing resin (9) does not protrude to the inner and outer peripheries of the substrate (6).

Thereafter, the stand bar holder (11) is further moved, and the glass substrate (6) in close contact with the stand bar (10) is transported under the light source (13).

Then, as shown in FIG. 5(e), ultraviolet rays are irradiated from the glass substrate (6) side, and the glass substrate (6) and the standby (1)
0) The ultraviolet curing resin (9) filled between the two is cured by photopolymerization. At this time, the ultraviolet curing resin (9) protrudes from the inner and outer edges of the glass substrate (6).
Since it doesn't last long, it won't harden and become crispy.

As a result, the uneven pattern on the surface of the standber (lO) was transferred to the ultraviolet curing resin layer on the glass substrate (6).

After transferring the uneven pattern, as shown in FIG. 5(f), the glass substrate (6) is peeled off from the stand bar (10),
The third substrate transfer mechanism transfers the substrate to the substrate unloading section (4) and accommodates it in the cartridge (14).

And a glass substrate (6) manufactured as described above.
By forming an appropriate functional film on the ultraviolet curable resin layer, a digital audio disk or a magneto-optical disk can be obtained.

For example, digital audio discs and so-called CD-
In a ROM or the like, a metal reflective film such as Af is formed on an ultraviolet curable resin layer onto which a concavo-convex pattern has been transferred. In a magneto-optical disk, a perpendicularly magnetized film (eg, TbFeCo, etc.) having magneto-optical properties (Kerr effect or Faraday effect) is formed.

[Effects of the Invention] As is clear from the above explanation, in the present invention,
Since escape grooves for ultraviolet curing resin are formed near the inner peripheral edge and/or near the outer peripheral edge of the glass substrate,
The surplus ultraviolet curable resin when the stand bar is in close contact with the stand bar can be trapped by the escape groove, and the extrusion of the ultraviolet curable resin can be prevented.

Therefore, it is possible to reliably prevent the occurrence of flakes on the inner and outer edges of the glass substrate, and it is possible to significantly improve the yield.

[Brief explanation of drawings]

1 and 2 show an example of a glass substrate for an optical disk to which the present invention is applied, and FIG. 1 is an enlarged plan view, and FIG.
The figure is a sectional view thereof. FIG. 3(A) to FIG. 3(D) are enlarged cross-sectional views of main parts showing examples of groove shapes of relief grooves, and FIG. 3(A)
3(B) is an example in which the groove wall is substantially perpendicular to the main surface of the glass substrate, FIG. 3(B) is an example in which one groove wall is inclined, and FIG. 3(C) is an example in which both groove walls are slanted. For example, the wall is sloped,
FIG. 3(D) is an example of a circular arc shape. FIG. 4 is a schematic plan view showing an example of an optical disc manufacturing apparatus for transferring the uneven pattern of the stand bar. Figures 5(a) to 5(f) sequentially show the steps of manufacturing an optical disc by the 2P method, and Figure 5(a)
) is a schematic perspective view showing the screen printing process;
FIG. 5(b) is a schematic perspective view showing a glass substrate printed with an ultraviolet curable resin, FIG. FIG. 5 is a schematic perspective view showing a pressure bonding process using a roller;
FIG. 5(e) is a schematic perspective view showing the ultraviolet irradiation process, and FIG. 5(f) is a schematic perspective view showing the peeling process from the stamper. FIG. 6 is a plan view showing an example of an opening pattern provided on the printing screen. 6...Glass substrate 9...UV curable resin lO...Stand bar 18...Center hole 19.20...Escape groove for UV curable resin +9a, 19
b...Groove wall

Claims (1)

[Claims] A glass substrate for an optical disc, comprising a disc-shaped glass substrate having a center hole, and an escape groove for an ultraviolet curing resin formed near the inner circumferential edge and/or near the outer circumferential edge.