Apparatus for manufacturing optical information recording medium

A disk substrate is supported by a support base formed on a center pin which is vertically movable on a selective basis, a table is set below the disk substrate, and a stamper is positioned on the table by means of a guide ring or the like. A ring-shaped portion of resin which is cured upon radiation of ultraviolet rays is set on the stamper. The center pin is then caused to descend by means of a drive mechanism, to a first position, at which position the disk substrate is on the point of contact with the resin. Then, the disk substrate is caused to descend intermittently in units of very small amounts, to a second position, at which position the entire periphery of the ring-like resin is brought into contact with the disk substrate. From the second position, the disk substrate is made to descend by means of the a load of a weight while, at the same time, the ring-shaped portion of resin is drawn by vacuum suction from its central position, thereby forming on the surface of the stamper a resin layer on which a record, formed on the stamper, is imprinted.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to an apparatus for manufacturing an optical 
information recording medium such as a disk for use in recording of 
digital data, and from which recorded information is read by using a laser 
beam. Such a recording medium is used in, for example, audio and video 
systems and in data recording of an information equipment. 
2. Description of the Related Art 
A method disclosed in Japanese Patent Disclosure (Kokai) No. 62-187004 is 
known as a means for manufacturing an optical disk. In this manufacturing 
method, a resin which cures upon radiation of ultraviolet rays thereon is 
sandwiched between a stamper having on its surface undulations for 
expressing data, and serving as a master and a disk substrate composed of 
a synthetic resin. Radiation of ultraviolet rays onto the layer of 
ultraviolet-curing resin, now having the undulated surface of the stamper 
imprinted thereon, causes the resin layer to be formed integral with the 
surface of the disk substrate. Thereafter, the resin layer and the stamper 
are separated, leaving a disk having an optical information recording 
surface formed thereon. 
In order to manufacture an optical disk as described above, the 
ultraviolet-curing resin layer located between the disk substrate and the 
stamper must be formed having a uniform thickness. Exemplary methods of 
forming this resin layer are those disclosed in Japanese Patent Disclosure 
(Kokai) Nos. 53-116105 and 58-173623. However, using even these methods, 
bubbles are sometimes formed in the resin layer. Consequently, it is 
difficult, using conventional methods, to manufacture, on a consistent 
basis, optical disks with high precision through preventing formation of 
bubbles. 
In addition, the resin layer on which the data recorded on the surface of 
the stamper is imprinted, upon radiation thereon of ultraviolet rays, must 
subsequently be separated from the stamper. Japanese Patent Disclosure 
(Kokai) No. 62-187004, for example, teaches a method wherein a push-up 
member located at a central portion of the disk substrate is pushed upward 
by a pin operated by air pressure, thereby to separate the resin layer 
from the stamper surface. 
However, when such a mechanical force is used to separate the resin layer 
from the stamper, it creates a strong flexing force which acts not only on 
the disk substrate but also on the resin layer on which the recorded data 
has been imprinted, thereby damaging that surface of the resin layer. 
Further, the flexing force may cause distortion of, the disk substrate 
which supports the resin layer, and, when the disk substrate is pushed 
upward, the stamper may become separated from its support table and be 
pushed upward together with the disk substrate, i.e. resulting in 
non-separation of these two elements. 
In consideration of the above problems, a method of fixing the stamper to 
the table has been proposed in Japanese Patent Disclosure (Kokai) No. 
60-47253. According to this method, a first electromagnet is located at a 
position corresponding to a central portion of the stamper, and a second 
ring-like electromagnet is set to correspond to the periphery of the 
stamper, thereby attracting and holding the stamper consisting of a 
magnetic material. To separate the resin layer from the stamper, the first 
electromagnet is switched off, with the periphery of the stamper remaining 
attracted to the second electromagnet. In this state, by moving the 
stamper away from the resin layer, the resin is separated sequentially 
from the periphery of the stamper. However, this separating method 
requires a complicated arrangement of first and second electromagnets set 
in correspondence with the shape of the stamper. In addition, a 
complicated on/off control must be performed in respect of the two 
electromagnets, and an undesirably strong force acts on the resin layer 
during its separation from the stamper. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide an apparatus for 
manufacturing an optical information recording medium such as an optical 
disk, in which a manufacturing process efficiently and automatically 
advances to manufacture an optical information recording medium with 
stable quality. 
It is another object of the present invention to provide an optical 
recording medium manufacturing apparatus in which no bubbles remain in a 
resin layer portion on which data is transferred and recorded from a 
stamper in the above manufacturing process, thereby successively 
manufacturing a highly reliable information recording medium having good 
optical characteristics. 
It is still another object of the present invention to provide an optical 
disk manufacturing apparatus in which a resin layer formed between a disk 
substrate and a stamper and having recorded data of the stamper 
transferred thereon can be easily and reliably peeled from the surface of 
the stamper without applying a peeling force on the resin layer, and this 
peeling step can be automatically performed, thereby manufacturing an 
optical disk with high reliability. 
In an optical information recording medium manufacturing apparatus 
according to the present invention, a disk substrate is supported by a 
center pin, and this center pin is vertically driven. In addition, a table 
is set to be selectively rotated about the center pin, and a stamper is 
placed on this table. A resin having a property of curing by ultraviolet 
rays is formed into a ring-like shape on the stamper. The disk substrate 
is moved downward toward the surface of the stamper on which the resin 
ring is formed. When the surface of the disk substrate is brought into 
contact with part of the resin on the stamper, the disk substrate is 
intermittently moved downward in units of very small distances thereafter. 
When the entire periphery of the ring like-resin is brought into contact 
with the surface of the disk substrate in this manner, only the center pin 
is moved downward so that the resin interposed between the disk substrate 
and the stamper is spread on the stamper surface by the load of a weight 
set on the substrate. 
In this case, the stamper is set on a table consisting of a magnet and kept 
at a predetermined position by a guide ring formed on the table. An air 
injection port is formed in a central portion of the table to inject air 
between the stamper and the resin layer. 
In the manufacturing apparatus having the above arrangement, part of the 
ring-like resin formed on the surface of the stamper is brought into 
contact with the disk substrate, and then the substrate is intermittently 
moved downward to gradually increase a contact area between the resin and 
the disk. Finally, the entire periphery of the ring-like resin is brought 
into contact with the disk substrate. Thereafter, the resin on the stamper 
is compressed and spread to form a layer by the weight of the disk 
substrate portion. Therefore, it was confirmed by repetitive experiments 
that the resin layer having a uniform thickness could be formed with high 
stability between the stamper and the disk substrate, and bubbles in the 
resin layer were effectively exhausted. 
In addition, the stamper is held on the table by a magnetic attracting 
force and kept at a predetermined position by the guide ring. After the 
cured resin layer is formed between the disk substrate and the stamper, 
the disk substrate is moved upward by a very small distance to separate 
the central portion of the disk substrate from the stamper surface by a 
very small distance, thereby forming a gap therebetween. Air is then 
supplied into the gap to peel the resin layer from the central portion of 
the stamper. That is, the resin layer can be peeled from the stamper while 
it is kept in contact with the disk substrate without applying a peeling 
force on the resin layer. As a result, a highly reliable optical disk can 
be manufactured.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIG. 1, an optical disk manufacturing apparatus comprises a 
center pin 11 serving as the center of a manufacturing operation and a 
valve member 12 constituted by a cylindrical body. The valve member 12 is 
vertically set, and the center pin 11 is inserted in a hollow portion of 
the valve member 12 so as to be freely moved in the axial direction in the 
hollow portion of the valve member 12. The valve member 12 is movably set 
in a hollow portion of a support member 13 constituted by a cylindrical 
body. 
That is, the valve member 12 is vertically supported to be vertically 
movable by the support member 13, and the center pin 11 is vertically 
supported to be vertically movable by the valve member 12. The support 
member 13 is vertically supported by a bearing mechanism 14 with respect 
to a base 15 so as to be rotatable in a horizontal plane. The base 15 
coaxially supports the support member 13, the valve member 12 and the 
center pin 11. 
A gear 131 is integrally mounted on the support member 13 so that the 
member 13 is rotated upon rotation of the gear 131. A horizontal receiving 
base 16 is formed at the upper portion of the support member 13. A 
disk-like table 17 is set on the receiving base 16, and a stamper 18 is 
placed on the table 17. The table 17 consists of a magnet and attracts and 
holds the stamper 18 consisting of a magnetic metal by a magnetic force. 
That is, since the table 17 need only hold the stamper 18 by a magnetic 
force, the entire table 17 need not consist of a magnet as long as the 
magnetic force acts on the surface of the table 17. Although not shown in 
detail, the table 17 may have a permanent magnet embedded therein. 
A circular guide hole is formed in a central portion of the stamper 18, and 
grooves or undulations for recording information bits are formed on its 
upper surface. A guide ring 19 formed integrally with the table 17 is 
fitted in the hole at the center of the stamper 18, thereby positioning 
the stamper 18 on the table 17. 
An inner circumferential portion of the upper end portion of the guide ring 
19 is tapered to form a valve seat, and a valve body 20 integrally formed 
at the upper end of the valve member 12 is brought into contact with this 
valve seat portion. That is, the valve member 12 is vertically moved as 
indicated by an arrow A, and the valve body 20 of the member 12 is brought 
into contact with or separated from the valve seat of the guide ring 19 
accordingly. 
For example, when the valve member 12 is located at a lower position as 
shown in FIG. 1, the valve body 20 is in contact with the valve seat of 
the guide ring 19. When the valve member 12 is moved upward from this 
position, a path is defined between the valve body 20 and the guide ring 
19. 
This path defined between the valve seat and the valve body 20 communicates 
with a path 21 formed in the receiving base 16, and the path 21 
communicates with a vacuum source (not shown). Alternatively, the path 21 
is caused to selectively communicate with the outer atmosphere via a 
switching valve. 
An air path 22 is formed in the center pin 11 to correspond to its central 
axis portion and communicates with a path 23 formed in the valve member 
12. The path 23 is open at the upper end face of the valve member 12 so 
that air supplied to the path 22 in the center pin 11 is injected from a 
disk-like receiving tray 24 formed to be recessed at a central portion of 
the table 17. 
The center pin 11 is vertically moved as indicated by an arrow B by a drive 
mechanism 25. The drive mechanism 25 comprises a screw shaft 252 rotated 
by a servo motor 251, and the center pin 11 is supported by a moving body 
253 threadably engaged with the screw shaft 252. By controlling a 
rotational angle of the servo motor 251, the center pin 11 is vertically, 
precisely moved in units of .mu.m. The rotational angle of the servo motor 
251 is controlled by a control circuit 26 comprising a microcomputer and 
the like. 
A flange-like support base 27 is formed at an upper portion of the center 
pin 11 so that the center pin 11 projects upward from the support base 27. 
A disk substrate 29 is placed on the support base 27 so that its central 
position is set by the center pin 11. 
The disk substrate 29 consists of a thermosetting resin such as an epoxy, 
an epoxy vinyl ester or a nonsaturated polyester, a thermoplastic resin 
such as a polymethyl methacrylate or a polycarbonate, or a 
light-transmitting material such as glass. 
When the center pin 11 is moved downward, the support base 27 is fitted in 
the recess portion of the receiving tray 24. 
A disk-like weight 31 consisting of a transparent body such as glass is 
placed on the disk substrate 29 supported by the center pin 11. The weight 
31 is supported by a moving base 30 which is set inside a chamber 32 so as 
to be vertically movable. The chamber 32 is vertically movable as 
indicated by an arrow C. Referring to FIG. 1, the chamber 32 is set at a 
lower position. In this state, the lower end of the chamber 32 is in 
contact with the surface of the base 15 to define a chamber room 33 sealed 
on the upper surface of the base 15, and the table 17 is set in the 
chamber room 33. 
An ultraviolet source (not shown) is located above the weight 31 in the 
chamber room 33 and radiates ultraviolet rays onto the surface of the 
stamper 18 placed on the table 17 through the transparent weight 31 and 
the disk substrate 29. 
A resin 36 as a material for forming a recording layer of an optical disk 
is set on the stamper 18 subjected to radiation of ultraviolet rays. The 
resin 36 consists of a 2P (Photo Polimar) resin material which is cured 
upon radiation of ultraviolet rays. More specifically, the resin 36 is a 
liquid resin having an acryl group and/or an methacryl group at its 
terminal end, e.g., an acrylic and/or methacrylic ester of an epoxy resin, 
a urethane resin having an acryl group and/or a methacryl group at its 
terminal end, or a resin prepared by diluting the liquid resin by a 
reactive monomer having an acryl group and/or a methacryl group. 
A predetermined amount of the resin 36 is injected from a nozzle mechanism 
37 moved on the stamper 18 as indicated by an arrow while the table 17 is 
rotated, thereby forming a ring-like resin. The table 17 is rotated 
together with the support member 13 by rotating the gear 131. 
FIG. 2 shows a processing flow of the control circuit 26 for controlling 
the movement of the center pin 11 and other manufacturing operations in a 
step of forming a recording layer of an optical disk. 
In step 101, the center pin 11 is initially set at an upper position as 
shown in FIG. 3. In this process, the nozzle mechanism 37 and the like are 
controlled to set the ring-like resin 36 about the center pin 11 in resin 
setting step 51. While the center pin 11 is kept at the upper position, a 
conveyor mechanism 40 conveys the disk substrate 29 to a position above 
the center pin 11 and sets the substrate 29 on the support base 27 fitted 
on the center pin 11 in substrate setting step 52. Before this process, 
the chamber 32 is moved upward from the position shown in FIG. 1 so as not 
to interfere with the movement of the conveyor mechanism 40. When the disk 
substrate 29 is set on the center pin 11 as described above, the chamber 
32 is moved downward to the position shown in FIG. 1 in chamber descending 
step 53. 
After the substrate 29 is set on the pin 11 in this manner, the weight 31 
is placed on the substrate 29 as shown in FIG. 4 in weight setting step 
54. In this case, the valve member 12 is set at a lower position as shown 
in FIG. 4. 
After the disk substrate 29 is set at a predetermined position and the 
weight 31 is placed on the substrate 29 as described above, in step 102, 
the center pin 11 is moved downward until an interval between the stamper 
18 and the substrate 29 is set in a first state. The first state shown in 
FIG. 5 is set immediately before the lower surface of the disk substrate 
29 is brought into contact with the ring-like resin 36. 
After the center pin 11 is moved downward to set the interval between the 
substrate 29 and the stamper 18 in the first state, in step 103, the 
center pin 11 is intermittently moved downward every one to several 
seconds in units of microns. During an intermittent downward movement of 
the pin 11, part of the resin 36 is brought into contact with the lower 
surface of the disk substrate 29, and this contact portion area is 
gradually enlarged. Finally, the entire periphery of the ring-like resin 
36 is brought into contact with the substrate 29. 
In step 104, the control circuit 26 checks whether the interval between the 
stamper 18 and the disk substrate 29 is set in a second state. If the 
circuit 26 determines that the interval is set in the second state, the 
downward movement of the center pin 11 is stopped, and the flow advances 
to step 105. In the second state, the interval is set such that the entire 
periphery of the ring-like resin 36 is brought into contact with the disk 
substrate 29. The value of this interval is experimentally obtained and 
arbitrarily stored. 
In step 105, the center pin 11 is further moved downward. This downward 
movement is continued until a support surface of the support base 27 of 
the center pin 11 is moved downward to a position separated from the 
surface of the stamper 18 by a predetermined distance, i.e., a position at 
a height corresponding to the thickness of a resin recording layer of an 
optical disk to be manufactured. When the pin 11 is moved downward to a 
position at which the support surface of the support base 27 is located at 
the height corresponding to the thickness of the recording layer above the 
surface of the stamper 18, the downward movement of the pin 11 is stopped. 
In this case, since the disk substrate 29 is supported by the resin 36, 
only the center pin 11 is moved downward to the predetermined position. 
At the same time, in vacuum suction step 55, the valve member 12 is moved 
upward as shown in FIG. 6 to separate the valve body 20 from the guide 
ring 19, thereby defining a suction path between the guide ring 19 and the 
valve body 20. 
In this state, a room surrounded by the ring-like resin 36 is formed 
between the stamper 18 and the substrate 29 and evacuated by the vacuum 
source. Since the load of the weight 31 acts on the resin 36 via the 
substrate 29, the resin 36 is gradually pressed by this load and spread 
between the stamper 18 and the substrate 29. 
When the disk substrate 29 is brought into contact with the ring-like resin 
36, bubbles are sometimes formed in the resin. Therefore, immediately 
before the substrate 29 is brought into contact with the resin 36, the 
substrate 29 is intermittently moved downward every one second in units of 
microns so as to be brought into contact with the resin 36 at one portion. 
Thereafter, as the disk 29 is further intermittently moved downward, a 
contact portion between the substrate 29 and the resin 36 is expanded in 
both the right and left directions along the ring. Finally, the entire 
periphery of the ring is brought into contact with the substrate 29. When 
the contact portion is formed between the ring-like resin 36 and the disk 
substrate 29 in this manner, bubble formation in the resin 36 can be 
reliably prevented. 
If bubbles are still formed in the resin 36 even when the substrate 29 is 
brought into contact with the resin 36 as described above, the resin 36 is 
drawn by suction of the vacuum source from the center of the room 
surrounded by the resin 36 after the entire periphery of the resin 36 is 
brought into contact with the substrate 29. That is, the ring-like resin 
36 is drawn to move inward to push the bubbles formed in the resin 36 
outward. Such a phenomenon was confirmed by repetitive experiments, i.e., 
it was confirmed that the bubbles in the resin 36 were reliably 
eliminated. 
In step 106, 50 seconds, e.g., are waited to hold the above state. During 
this wait period, the ring-like resin 36 is spread between the stamper 18 
and the disk substrate 29 by the load of the weight 31, thereby reducing 
the height of the resin 36. The substrate 29 is moved downward with height 
reduction in the resin 36. 
After the resin 36 is completely spread between the stamper 18 and the 
substrate 29, i.e., a layer of the resin 36 is formed on the entire 
surface of the stamper 18 on which data is recorded, the substrate 29 
abuts against and is stopped by the support base 27 of the center pin 11 
which is moved downward in step 105, as shown in FIG. 7. 
In this state, since an interval between the stamper 18 and the substrate 
29 is numerically correctly set by the lower position of the center pin 
11, the thickness of the resin 36 on the data recorded surface of the 
stamper 18 can be easily and correctly controlled. 
In this case, the stamper 18 is correctly positioned and mounted on the 
table 17 and effectively prevented from being peeled from the table 17 by 
the guide ring 19. In addition, the path 21 communicating with the vacuum 
source is formed at the outer periphery of the guide ring 19, i.e., at the 
lower side of the inner periphery of the stamper 18. For this reason, even 
if the resin 36 reaches the rear side of the stamper 18 upon spreading of 
the resin on the surface of the stamper 18, this resin is drawn by vacuum 
suction and reliably recovered and removed therefrom. 
When the layer of the resin 36 is formed between the stamper 18 and the 
disk substrate 29 as described above, the substrate 29, the weight 31 and 
the like are rotated together with the table 17 as shown in FIG. 7 in 
table rotation step 56. In this state, in ultraviolet radiation step 57, 
ultraviolet rays are uniformly radiated on the entire surface of the resin 
36 through the transparent weight 31, as shown in FIG. 8. As a result, the 
layer of the resin 36 formed between the stamper 18 and the substrate 29 
is cured to form a recording resin layer 41. The record expressed by the 
undulations formed on the stamper 18 is transferred to the surface of the 
layer 41 opposite to the stamper 18. As a result, a recording surface of 
an optical disk is formed by the layer 41. 
In this manner, the resin layer 41 on which the recording surface is formed 
integrally with the disk substrate 29 is obtained, thereby completing a 
basic structure of the optical disk. Thereafter, since the substrate 29 
and the layer 41 must be integrally peeled from the surface of the stamper 
18, the chamber 32 must be moved upward in chamber lifting step 58 before 
a peeling step starts. 
The peeling step will be described below. In step 107, the center pin 11 is 
moved upward by a very small amount as shown in FIG. 9. In this case, the 
chamber 33 is set at its upper position, and the valve member 12 is set at 
its lower position to close the path communicating with the vacuum space 
between the guide ring 19, the valve member 12 and the valve seat 20. In 
air supply step 59, air is supplied through the air path 22 and the path 
23 formed in the valve member 12 and injected from the receiving tray 24. 
The injected air is supplied from the lower surface of the support base 27 
to the lower surface at the central portion of the disk substrate 29 and 
between the recording resin layer 41 and the stamper 18, thereby peeling 
the layer 41 from the stamper 18. At the same time, the weight 31 is 
removed and moved upward. 
When the center pin 11 is further moved upward in step 108, the layer 41 is 
smoothly peeled from the surface of the stamper 18 and moved upward 
together with the substrate 29 to a conveyance position, as shown in FIG. 
10. When the substrate 29 integrally having the layer 41 thereon is moved 
to the conveyance position, in disk discharging step 60, the conveyor 
mechanism 40 is controlled to chuck and convey the substrate 29 to a 
predetermined storage position. 
The disk substrate 29 having the recording resin layer 41 is completed as 
an optical disk via a reflecting layer or protection film formation step.