JP2001143334A - Spreading method for optical disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for spreading an adhesive which is capable of surely spreading the adhesive even on a disk substrate having a burr, etc., when adhering an optical disk. SOLUTION: This method for spreading an adhesive for an optical disk has the following stages 1 to 5; (1) the stage for placing the first disk substrate D1 on a rotary holding table X, (2) the stage of applying the adhesive R to the first disk substrate D1, (3) the stage for placing and superposing the second disk substrate D2 on the first disk substrate D1, (4) the stage for holding the superposed and placed first disk substrate D1 and second disk substrate D2 and spreading the adhesive by rotating the disk substrates while sucking the adhesive through the boss parts inserted into their central holes and (5) the stage for sucking the adhesive again from the boss parts after the end of the rotation of the previous stage and eliminating the air gaps.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for bonding two circular substrates together on an optical disc, and more particularly, to a method for spreading an adhesive on an optical disc.

[0002]

2. Description of the Related Art In recent years, the capacity of storage media used in personal computers and the like, particularly optical disks, has been increasing in density.
There are many types. Above all, the demand for optical disks is prominent.

[0003] In the case of an optical disk called a DVD as an example, it is standardized that a single disk substrate constituting the DVD has a thickness of 0.6 mm, an outer diameter of 120 mm, and an inner diameter of a center hole of 15 mm. Two such thin disk substrates are bonded together to form an optical disk having a large storage capacity and a sufficiently high mechanical strength. The following series of steps are performed for this bonding (see FIG. 11).

(1) A first disk substrate D is mounted on the rotation support X.
(2) Step of applying adhesive R to first disk substrate D1 (3) Second disk substrate D on first disk substrate D1
(4) Step of spreading adhesive R interposed between both disk substrates D1 and D2 (5) Step of curing spread adhesive R

To briefly explain the above steps, first, in step (1), a first disk substrate D1 having a signal surface coated with a reflective film and a protective film is uniformly attracted and held on a rotary holding table X. . The first surface of the rotation holding table 1
A large number of suction holes for holding the disk substrate D1 by suction are provided, and the suction holes are sucked through a suction passage (not shown) to ensure reliable suction.

In the step (2), an adhesive R is applied. The adhesive R, for example, an ultraviolet curable resin is discharged from the discharge nozzle N while the rotation support X on which the first disk substrate D1 is mounted is rotated at a low speed. Discharge. The adhesive to be discharged is
The trajectory ejected onto the first disk substrate D1 differs depending on the manner of ejection from the ejection nozzle N, but it is preferable to form the trajectory as, for example, an O-shaped trajectory as shown in the figure.

In step (3), the second disk substrate D2 is placed on the first disk substrate D1 to which the adhesive R has been applied.

Next, in step (4), both disk substrates D
1 and D2, so that the adhesive R interposed therebetween is spread evenly and evenly. In this extension, the rotation holding table X is rotated at a high speed (typically, the rotation speed is several thousand rpm or more, and the rotation time is longer) in a state where the combined disk substrate in which the two disk substrates D1 and D2 are combined, that is, the optical disk D is mounted. Is performed for about several seconds).

By this rotation, the excess adhesive R present between the bonded disk substrates D1 and D2 is scattered outside together with the spreading, and at the same time, the disk substrates D1 and D2
The air (such as air bubbles) trapped in between is released to the outside and is uniformly spread between the two resin substrates. However, in the spreading process, the adhesive R is only spread outward, and has a disadvantage that it is difficult to spread in the center direction.

[0010] That is, the adhesive R is centrifugally extended by the rotation of the rotary holding table and spreads outward. However, the adhesive R does not sufficiently spread to the position of the liquid stopping groove and the spreading is insufficient. The result is that air remains. Therefore, the adhesive is sucked from the boss inserted into the center hole of the optical disk.

In the step (5), the first disk substrate D1 and the second disk substrate D2 which are superposed are rotated (for example,
In this state, ultraviolet rays are irradiated to cure an adhesive, for example, an ultraviolet curable resin layer. As described above, the united bonding step is completed.

[0012] Of all the above-mentioned steps, the spreading step, in particular, is to spread the adhesive R evenly and uniformly between the disk substrates, and is positioned at a necessary portion.
In the extension step, as described above, appropriate suction from the boss portion is performed to sufficiently spread the adhesive R in the region near the center hole. Then, the extension from the position of the liquid stopping groove to the outer peripheral end of the disk can be achieved.

By the way, recently, disk substrates to be bonded are manufactured under strict quality control.
Some of them have burrs at the ends of the liquid stopping grooves. The burrs are generated when the disk substrate is injection-molded. Recently, since sufficient quality control has been performed, the disk substrate having large burrs is eliminated by inspection as much as possible. However, many lots sometimes include a disk substrate having such burrs, and burrs generated at the ends of the liquid stopping grooves adversely affect the spread. That is, when burrs are formed in the liquid stopping groove, voids are formed outside the burrs, which are shadow portions of the burrs.

The void will be described later with reference to FIG. If you analyze this gap in detail,
It can be seen that the portion is not filled with the adhesive. This gap is formed as a portion where the adhesive is not filled in a part in a radially outward direction due to a lack of suction force by the boss portion due to burrs when the disk is rotated and the boss portion is insufficient. Things.

In the front view, the gap is formed to extend behind the burr (when the center direction is set to the front), and this portion is a disadvantageous portion depending on the type of DVD. When an ultraviolet-curable and anaerobic resin is used as the adhesive, the periphery of the void is not cured, resulting in poor quality. If the adhesive is exposed due to a breakage accident, the uncured adhesive may have an adverse effect. For this reason, it is necessary to reliably avoid the phenomenon in which the voids occur.

[0016]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems in view of the above technical background. That is, an object of the present invention is to provide a method of spreading an adhesive which can accurately spread an adhesive even on a disk substrate having burrs or the like when bonding an optical disk.

[0017]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies on such a problem, and as a result, after the rotation for extension is completed, suction is performed again from the boss portion. To solve traditional problems.
The present invention has been completed based on this finding.

That is, according to the present invention, (1) an optical disk having an adhesive interposed between two disk substrates having a center hole is placed on a rotary holding table, sucked and held, and inserted into the center hole. A method of spreading the adhesive by rotating while rotating by using the boss portion of the rotation holding table, which is a method of spreading the adhesive again from the boss portion after the rotation is completed. .

(2) Re-suction from the boss portion
The present invention resides in the method of (1) for spreading the adhesive, which is performed without rotating the rotation holder.

Further, (3) a method for spreading an adhesive on an optical disk, comprising the following steps 1 to 5: 1) A step of mounting the first disk substrate D1 on the rotation holder X 2) A step of applying an adhesive R to the first disk substrate D1 3) A second disk substrate D2 on the first disk substrate D1
4) The first disk substrate D1 and the second disk substrate D1
A step of holding the disk substrate D2 and rotating it while sucking it through the boss portion inserted into the center hole to spread the adhesive. 5) A step of sucking again from the boss after the rotation in the previous step is completed to eliminate the gap.

(4) The method for spreading an adhesive according to the above (3), wherein the negative pressure of suction in the step 4 is -5 to -20 mmHg.

(5) The method for spreading an adhesive according to the above (3), wherein the negative pressure for re-suction in the step 5 is -70 to -100 mmHg.

(6) The method for spreading an adhesive according to (3), wherein the rotation time in step 4 is 8 to 10 seconds and the suction time is 3 to 6 seconds in the first half.

(7) The method for spreading an adhesive according to the above (3), wherein the suction time in the step 5 is 0.3 to 3 seconds.

Also, (8) a method for spreading an adhesive on an optical disk, comprising the following steps 1 to 5: 1) A step of mounting the first disk substrate D1 on the rotation holder X 2) A step of applying an adhesive R to the first disk substrate D1 3) A second disk substrate D2 on the first disk substrate D1
4) The first disk substrate D1 and the second disk substrate D1
Holding the disc substrate D2 and rotating the same for 8 to 10 seconds while sucking the first 3 to 6 seconds at a negative pressure of -5 to -20 mmHg through a boss inserted into the center hole to spread the adhesive. 5) After the rotation in the previous process is completed, the boss portion is again moved to -7
A step of sucking at a negative pressure of 0 to -100 mmHg for 0.3 to 3 seconds to eliminate the voids

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, when spreading an adhesive,
The rotation holder used to rotate the optical disk will be described. FIG. 1 is a cross-sectional view (A-A cross section in FIG. 2) showing the rotation holding table X. FIG. 2 shows a top view of the rotation holding base X, and the lower half shows the arrangement of the air suction passage of the table body. A vertically movable dome Y for preventing the adhesive R from scattering when spreading is arranged around the rotation holding table X, but a detailed description of the dome is omitted.

As shown in FIG. 1, the rotation support X is
It has a mounting portion for mounting the disk substrates D1 and D2, and a rotation support shaft 3 for supporting the mounting portion. The mounting portion is configured by the table body 2 being fitted and attached to the large-diameter portion 31 of the rotation support shaft 3. A boss body 1 is provided in a fitting hole 32 provided in the large-diameter portion 31 of the rotation support shaft 3.
Is fitted and attached.

The boss body 1 is detachable from the fitting hole 32. However, when the boss body 1 is fitted and set, it is temporarily fixed with an adhesive so that air does not leak. (Note that
The boss 1 is divided into a base 11 and a lid 12, and the lid 12 is fixed to the base 11 with screws or the like. The suction from the boss body 1 is performed through a suction port B1 formed by a gap between the base 11 and the lid 12. Suction port B
Numeral 1 communicates with an internal space B2 of the boss body, and the internal space B2 is connected to a passage B3 penetrated by the rotation support shaft 3.

Further, the lower end of the rotary support shaft 3 is joined to a rotary joint R, and an internal passage B3 is connected to an externally controlled negative pressure source (not shown, such as a vacuum source) through the rotary joint. A suction device is adopted). As described above, a continuous suction passage for sucking the adhesive is formed by the suction port B1, the internal space B2, the passage B3, and the like.

On the other hand, the table body 2 is a portion (mounting portion) on which the optical disk D is directly mounted, and has a flat seating surface. A large number of suction holes A1 are provided on the surface of the rotation support shaft 3. The suction holes A1 communicate with a passage A3 formed in the large-diameter portion 31 of the rotation support shaft 3 via a passage A2 in the table.

The passage A3 is opened to a space (gap) A4 between the rotary support shaft 3 and the fixed support shaft 4. The rotation support shaft 3 is rotatably supported by a fixed support shaft 4 via a bearing 41. The space A4 is formed as a cylindrical space sealed between the two. Therefore, strict airtightness is ensured between the fixed support shaft 4 and the rotary support shaft 3 by using the seal body 42.

The space A4 is opened to the outside by a through-hole A5 provided at an appropriate vertical position of the fixed support shaft 4, and is connected to a controlled negative pressure source (not shown) through the through-hole A5. They are connected using a pipe or the like. As described above, a continuous suction passage for sucking the optical disk is formed by the suction hole A1, the passage A2, the passage A3, the space A4, the through-hole A5, and the like. By operating a suction source (not shown), the suction hole A1 becomes a negative pressure, and a suction force acts on the surface (seating surface) of the table body as a mounting portion, and the optical disc D mounted thereon absorbs the suction. Will be retained.

On the other hand, a timing pulley TP is provided at the lower end of the rotation support shaft 3, and when the rotation support shaft 3 rotates via a timing belt (not shown), the entire rotation holding table is integrated. Rotated. By the way, in order to assemble the rotation holding base X, first, the table body 2 is fitted and fixed to the large-diameter portion 31 of the rotation support shaft 3. Here, since the large-diameter portion 31 comes out to the center of the table body 2, the boss body 1 may be fitted into the fitting hole 32 provided in the large-diameter portion 31.

When the center hole of the optical disc has a different size and the boss 1 must be replaced, the boss 1 is removed from the large diameter portion of the rotary support shaft in a state where the optical disc D is not mounted, and the boss 1 is replaced. Then, another different boss body may be fitted therein. However, depending on the type of the optical disk, it is necessary to replace the table body 2 with a different size. In such a case, the table body 2 suitable for the optical disk is mounted.

By the way, when the optical disk D is mounted, a space S (see FIG. 3) is defined by the boss 1 and the upper surface of the large-diameter portion of the rotation support shaft 3 and the lower surface of the optical disk D.

The manner in which the adhesive R on the optical disk is spread by using the above-described rotation holder X will be described.
FIG. 10 is a block diagram showing a series of extension steps.
First, the D on the first disk substrate is placed on the rotation holder X shown in FIG.
1 is mounted (disk substrate mounting step).

Next, the adhesive R is applied to the surface of the first disk substrate D1 placed on the rotation holding base X (adhesive applying step). When the second disk substrate D2 is placed on the first disk substrate D1 and superimposed, the optical disk formed between the two disk substrates with the adhesive R interposed therebetween is rotated by the rotation holder X.
(A disc substrate superimposing step). The boss of the rotation holder X is inserted into the center hole of the optical disc, and the optical disc is positioned correctly. Here, the suction source of the suction passage A is operated to suck and hold the optical disk through the suction hole A1 (normally, a negative pressure of about several hundred mmHg).

Next, the rotation holding table X is rotated at a high speed, and the suction source of the suction passage B is activated almost simultaneously or slightly later to perform suction through the suction port B1 of the boss 1 (adhesive spreading step). In this case, the negative pressure for suction is -5 to -20 mmHg from the viewpoint of the spreading efficiency, and the rotation time is 8 mm.
-10 seconds is preferred. Similarly, the suction time is 3 to
Six seconds is preferred. Due to the centrifugal force caused by the high-speed rotation, the adhesive interposed between the two disk substrates D1 and D2 is spread, and excess adhesive is scattered to the outside. At this time, the air interposed between the disk substrates D1 and D2 is also discharged to the outside together with the excess adhesive. As described above, the adhesive scattered to the outside is received by the receiving dome Y to prevent pollution of the environment.

FIGS. 3 and 4 show that when this suction is started,
As the air is sucked from the suction port B1 of the boss body 1, the state in which the adhesive R is drawn into the vicinity of the center holes of the disk substrates D1 and D2 is determined by the rotation holding table X including the boss portion 1 and the optical disk. It is schematically shown using the part,
FIG. 3 is a partial cross section, and FIG. 4 is a partial front view. When sucked from the suction port B1 of the boss 1, the space between the disk substrate D1 and the disk substrate D2 has a negative pressure.

That is, the adhesive R interposed between the disk substrates D1 and D2 is drawn toward the center by the suction action as described above. Here, it is difficult to suction from the boss 1 in the extension process.
The purpose is to prevent the adhesive R from being excessively sucked toward the center side of the liquid stopping groove P provided at a certain distance from the center hole of the optical disc D by a suction action at a certain distance from the center hole of the optical disc D. If the adhesive is strongly sucked so as to erode into the central portion beyond the liquid stopping groove, the adhesive leaks out and adheres to the end, causing a defect that stains the vicinity of the central hole, and the boss 1 may be clogged. is there.

The degree of suction from the boss 1 is carefully determined from the viewpoint of the spreading efficiency in consideration of the viscosity of the adhesive R, the number of rotations of the rotation holder X, and the like. In that sense, negative pressure (suction force) and rotation time are employed as described above. By performing appropriate suction, both disk substrates D1, D
The adhesive existing in the vicinity of the liquid stop groove between the two generally becomes evenly and evenly distributed. However, in the case of a disk substrate in which a relatively large burr P1 is formed at the groove end of the liquid stopping groove P, after the rotation of the rotation holding table is completed, a void may be generated in a partial area shaded by the burr. , As described above. In the present invention, after the rotation of the rotary holder is completed to remove the gap, suction is further performed from the boss 1 (re-suction step).

FIGS. 5 and 6 schematically show a state in which a gap Q is formed after the rotation for extension is completed. FIG. 5 is a partial sectional view, and FIG. It is a front view. In the present invention, after the rotation for extension is completed, suction is performed again through the boss portion 1 so that the gaps disappear and reliable extension is performed.

7 and 8 show a state in which the gap Q has disappeared after suctioning again (FIG. 7 is a partial cross-sectional view, and FIG. 8 is a partial front view. When the suction (re-suction) from the boss 1 is performed again, the adhesive R enters the gap Q from the surroundings and is reliably filled, and the unfinished portion of the adhesive disappears. From the viewpoint of the spreading efficiency in consideration of the viscosity of the agent R and the like, in this re-suction, the negative pressure for the re-suction is preferably -70 to -100 mmHg, and the suction time is preferably 0.3 to 3 seconds.

In re-suction, it is preferable that a centrifugal force is not applied in order to eliminate a void portion, and it is not necessary to perform rotation. After the re-suction is completed, the disk substrate is released from the suction holding. Thus, the extension process is completed.
After the extension is completed, it is transferred to another station,
The adhesive is cured by irradiating the optical disc with ultraviolet light,
The disk substrates are firmly integrated.

FIG. 9 is a diagram illustrating the relationship between the rotation speed (the rotation speed of the rotation holding table = the rotation speed of the two disk substrates) and time for the extension and re-suction by the rotation accompanied by a series of suctions. It is. The rotation speed is increased to a certain number (for example, about 2800 RPM) within 3 seconds after the rotation starts, and the rotation is continued for 5 seconds. In this case, the suction by the boss portion is slightly delayed (for example, 0.5 seconds) after the rotation starts, and is performed in the first half of 4 seconds. After rotating for 5 seconds, the rotation is stopped immediately. In this case, the operation is stopped in about 0.5 seconds due to active stop. As soon as the rotation is stopped after the extension,
Perform for seconds. Although these specific numerical values are merely examples, the gap portion can be reliably eliminated by temporarily stopping the rotation due to the extension and then performing the suction again.

Although the present invention has been described above, the present invention is not limited only to the embodiment, and it goes without saying that various other modifications can be made without departing from the essence of the present invention. Absent. The re-suction time and the negative pressure for suction
Other than the values described above, it is possible to appropriately adopt the values.

[0047]

According to the present invention, after the main suction for extension of the suction by the boss portion is completed, the suction is performed again, so that the gap formed outside the burr is filled with the adhesive so that the whole is uniform and reliable. The spread of the adhesive is guaranteed. Therefore, even if a disk substrate having burrs is used, a high quality optical disk can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a rotation holding table of an optical disk.

FIG. 2 is a top view of the rotation holding table, and also shows an air suction passage of the table body.

FIG. 3 is a partial cross-sectional view schematically showing a suction state.

FIG. 4 is a partial front view schematically showing a suction state.

FIG. 5 is a partial cross-sectional view schematically showing a state in which a gap is formed.

FIG. 6 is a partial front view schematically showing a state in which a gap is formed.

FIG. 7 is a partial cross-sectional view schematically showing a state in which a gap has disappeared after suction has been performed again.

FIG. 8 is a partial front view schematically showing a state in which a void portion has disappeared after suctioning again.

FIG. 9 is a diagram illustrating the relationship between the number of rotations and time for extension and re-suction by rotation with a series of suctions.

FIG. 10 is a block diagram showing a series of extension steps.

FIG. 11 is a schematic process diagram showing a general process of manufacturing an optical disk by bonding a second disk substrate to a first disk substrate via an adhesive.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Boss part 11 ... Base part 11A ... Small hole 12 ... Lid part 2 ... Table body 3 ... Rotation support shaft 3A ... Rotation shaft body 31 ... Large diameter part 32 ... Fitting part 4 ... Fixed support shaft 41 ... Bearing 42 ... Seal body A suction path A1 suction hole A2 path A3 path A4 space B suction path B1 suction port B2 internal space B3 path C introduction path D optical disk (magnetic disk) D1 first disk substrate D2 ... Second disk substrate L ... Ultraviolet light source N ... Nozzle R ... Adhesive S ... Vacancy X ... Rotation holder Y ... Reception dome 4 ... Fixed support shaft

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Naoto Yano 98-1 Tsunowa, Tano-cho, Komatsushima City, Tokushima Prefecture F-term in Kitano Engineering Co., Ltd. (Reference) 4J040 LA10 MB05 MB15 NA17 NA21 PB01 PB11 PB21 5D121 AA03 AA07 EE22 EE23 EE28 FF01 FF13 FF18 GG02 GG30

Claims (8)

[Claims] 1. An optical disk having an adhesive interposed between two disk substrates having a center hole is placed on a rotation holder, held by suction, and a boss portion of the rotation holder inserted into the center hole. A method of spreading the adhesive by rotating while sucking using an adhesive, wherein after the rotation is completed, suction is performed again from the boss portion. 2. The method for spreading an adhesive according to claim 1, wherein the re-suction from the boss portion is performed without rotating the rotary holding table. 3. A method for spreading an adhesive on an optical disk, comprising the following steps 1 to 5. 1) A step of mounting the first disk substrate D1 on the rotation holder X 2) A step of applying an adhesive R to the first disk substrate D1 3) A second disk substrate D2 on the first disk substrate D1
4) The first disk substrate D1 and the second disk substrate D1
A step of holding the disk substrate D2 and rotating it while sucking it through the boss portion inserted into the center hole to spread the adhesive. 5) A step of sucking again from the boss after the rotation in the previous step is completed to eliminate the gap. 4. The negative pressure for suction in step 4 is -5 to -20 m
4. The method for spreading an adhesive according to claim 3, wherein the pressure is mHg. 5. The negative pressure for re-suction in step 5 is -70 to -1.
The method for spreading an adhesive according to claim 3, wherein the pressure is 00 mmHg. 6. The method for spreading an adhesive according to claim 3, wherein the rotation time in step 4 is 8 to 10 seconds, and the suction time is 3 to 6 seconds in the first half. 7. The method for spreading an adhesive according to claim 3, wherein the suction time in step 5 is 0.3 to 3 seconds. 8. A method for spreading an adhesive on an optical disk, comprising the following steps 1 to 5. 1) A step of mounting the first disk substrate D1 on the rotation holder X 2) A step of applying an adhesive R to the first disk substrate D1 3) A second disk substrate D2 on the first disk substrate D1
4) The first disk substrate D1 and the second disk substrate D1
Holding the disc substrate D2 and rotating the same for 8 to 10 seconds while sucking the first 3 to 6 seconds at a negative pressure of -5 to -20 mmHg through a boss inserted into the center hole to spread the adhesive. 5) After the rotation in the previous process is completed, the boss portion is again moved to -7
A step of sucking at a negative pressure of 0 to -100 mmHg for 0.3 to 3 seconds to eliminate the voids