JPH08273208A - Method and apparatus for manufacturing bonded disc - Google Patents

Abstract

(57) [Summary] [Purpose] The objective is to manufacture a flat bonded disk that is free from warpage and twist. A ring-shaped portion in which an adhesive is not applied to an outer peripheral portion and an inner peripheral portion of at least one of a pair of single-sided disks A and A'to be bonded by using an adhesive application means such as a screen printer 6 After the adhesive is applied so that each of the pair of single-sided disks A and A'is vacuum-sucked on the vacuum suction surfaces 21 and 31 of the suction tables 17 and 18, respectively, warp and twist of the respective disk surfaces are prevented. The pair of single-sided discs A and A ′ are pressure-bonded to each other in a state where the warp and the twist are corrected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for manufacturing a bonded disk made by bonding two disks such as an optical video disk.

[0002]

2. Description of the Related Art An optical video disk will be described as an example of a bonded disk. The optical video disc is a transparent plastic disc (single-sided disc) with pits formed on one side by injection molding.
The surface and the B surface are formed separately, and a metal reflective film such as aluminum is formed on the pit forming surface of these single-sided disks by a vacuum film forming method or the like, and then a protective film or an adhesive is applied on the metal reflective film. These two single-sided disks, the A-side and the B-side, are bonded together to form a single disk.

In such an optical video disc, a thermoplastic adhesive called hot melt is generally used as an adhesive for laminating the discs,
This was applied to the bonding surface of the single-sided disk by an adhesive application device such as a roll coater, and then bonded by the method as shown in FIG.

That is, in FIG. 7, 101 is a lower pressure bonding table, 102 is a movable upper pressure bonding table which is movable in the vertical direction, and is a pair of one-sided disks A, A'coated with hot melt. The lower pressure-bonding table 1 in a state where they are faced so that their adhesive surfaces face each other.
The center pin 103 of No. 01 was overlaid and overlapped, and in this state, the upper pressure bonding table 104 was lowered and pressed for a predetermined time for bonding.

[0005]

By the way, when bonded by the method as shown in FIG. 7, the two single-sided disks A and A'contact each other when they are placed on the upper pressure bonding table 101. However, some of them are bonded before being pressed by the upper pressure bonding table 102. Generally, the single-sided disks A and A'are not completely flat, and the surfaces thereof are usually warped or twisted as shown exaggeratedly in FIG. For this reason, as shown in FIG. 7, when the two single-sided disks A and A ′ are placed on the lower pressure-bonding table 101 in an overlapping manner, the two single-sided disks A and A ′ are warped or twisted, and part of their surfaces are bonded. However, even if the upper pressure bonding table 102 is pressed after this for bonding, it is difficult to bond the disk as a completely flat disk.

For this reason, the conventional bonded disk has a warp or twist on the disk surface to a greater or lesser degree, and the amount of the warp or twist also differs from one disk to another and is a completely flat bonded disk. There was a problem that it could not be manufactured stably.

Further, if the disc is largely warped or twisted, it sometimes causes a problem that the optical pickup of the player cannot read the bit information on the disc surface during reproduction. For this reason, a disc having a warp or a twist that exceeds the standard has to be pulled out and discarded at the time of the completion inspection, which is one of the causes of a decrease in the yield at the time of manufacturing the disc.

The present invention has been made to solve the above problems, and provides a disk manufacturing method and apparatus capable of manufacturing a flat bonded disk which is free from warpage and twisting as compared with the prior art. The purpose is to provide.

[0009]

In order to achieve the above object, a method for manufacturing a bonded disk according to the present invention is directed to at least one of a pair of single-sided disks to be bonded to an outer peripheral portion and an inner peripheral surface thereof. After applying the adhesive so that there is a ring-shaped part on which the adhesive is not applied, the pair of single-sided disks are vacuum-adsorbed on the vacuum adsorption surfaces of the adsorption tables to correct the warp and twist of each disk surface. It is characterized in that the adhesive surfaces of the pair of single-sided disks are pressure-bonded to each other while the warp and the twist are corrected.

In the above method, in order to provide the outer peripheral portion and the inner peripheral portion of the one-sided disk with the ring-shaped portions to which the adhesive is not applied, the protective film to be applied on the optical reflection film of the one-sided disk is applied with the adhesive in advance. It is applied only to the part, and the ring-shaped part where the adhesive is not applied is formed on the outer peripheral part and the inner peripheral part by the step due to the thickness of this protective film, or the thickness of the outer peripheral part and the inner peripheral part of the single-sided disk is preliminarily set. It is preferable to provide a step so that it is thinner than the portion to which the adhesive is applied, and form a ring-shaped portion to which the adhesive is not applied on the outer peripheral portion and the inner peripheral portion by this step.

In order to achieve the above-mentioned object, the bonded disk manufacturing apparatus according to the present invention has an adhesive on the outer peripheral portion and the inner peripheral portion of at least one of a pair of single-sided disks to be bonded. The adhesive applying means for applying the adhesive so that there is a ring-shaped portion on which the adhesive is not applied, and the disk adsorption portion of the adsorption arm are brought into contact with the outer peripheral portion and the inner peripheral portion of the single-sided disc which are not coated with the adhesive to form a vacuum. A disk transfer means for adsorbing and transferring it to the adsorption table of the disk bonding means, and a pair of single-sided disks transferred to the adsorption table are vacuum-sucked from the back side thereof to be vacuum-sucked on the flat vacuum adsorption surface of the adsorption table. The warp and twist of each single-sided disc are corrected by forcing, and the pair of single-sided discs are pressure-bonded to each other in the corrected state. It is characterized in that a click bonding means.

In the above apparatus, when the vacuum suction surface of the suction table of the disk bonding means is made of a porous member, the disk is vacuum-sucked from the back surface of the porous member, and a pair of single-sided disks are pressed. , Blow compressed air over the entire surface of the disk through the porous member,
It is preferable that the entire surface of the disk is pressed with a uniform force.

[0013]

Since the present invention is constructed as described above,
The warp and twist of the pair of disks to be bonded can be corrected in advance by vacuum suction and then bonded together. Therefore, it is possible to stably manufacture a large number of flat bonded disks without warping or twisting.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a schematic plan view showing the overall configuration of one embodiment of the bonded disk manufacturing apparatus of the present invention. In the figure, A,
A'is a pair of single-sided disks before bonding, and D is a completed disk after bonding the pair of single-sided disks A, A '. In this embodiment, the single-sided disks A, A '
This is an example of a case where an adhesive is applied to both of them and they are bonded together.

The single-sided discs A and A'are made of a transparent plastic such as polycarbonate (PC) or polymethylmethacrylate (PMMA), and are injection-molded as a transparent disc having information pits on one side. An aluminum reflection film is formed on the pit formation surface by a sputtering device, and an ultraviolet curing resin such as epoxy acrylate is uniformly applied as a protective film on the reflection film by a spiner. In the case of this embodiment, the single-sided discs A and A'are flat discs with a uniform thickness and a flat diameter of 300 mm, and a center hole is formed in the center thereof, and the protective film has a diameter of 60 to 300 mm. It is applied with a uniform film thickness in the range.

A single-sided disk A having the above structure,
A's were carried alternately from the previous step (protective film forming step) to the belt conveyor 1 with their adhesive surfaces facing upward, and were bonded to one disk in the bonded disk manufacturing apparatus 2 of the present invention. Later, finished disc D
Then, it is placed on the belt conveyor 1 again and transferred to a subsequent process (inspection process or the like).

Reference numeral 3 is a rotary table for applying adhesive to the single-sided disks A, A ', and 4 is a disk supply arm (robot) for transferring the single-sided disks A, A'from the belt conveyor 1 to the rotary table 3. Is. Four disk mounting portions 5 are formed on the rotary table 3, and the entire rotary table is sequentially rotated at a predetermined pitch in the arrow direction. The disc supply arm 4 sequentially adsorbs the one-sided discs A and A'which are transferred alternately on the belt conveyor 1 by the suction cup 4a at the tip thereof, and the disc mounting portion at the disc supply position P ₁ position of the rotary table 3. Reprinted in 5.

Adhesive application position P on the rotary table 3
_{At the 2} position, a UV adhesive (= liquid at room temperature, an adhesive that shows adhesiveness when irradiated with ultraviolet rays) or a cation-polymerizable UV-curable adhesive (= room temperature) on the protective film of the single-sided disks A and A ′. A screen printing machine 6 for applying a desired adhesive such as a liquid, an cation that causes a curing reaction upon irradiation with ultraviolet rays, which cures in a few seconds to a few minutes, to a predetermined thickness is arranged. There is. In the case of this embodiment, the screen printing machine 6 prints and applies the adhesive in a ring shape over a range of φ40 to 295 mm on the protective film of the one-sided disks A and A ′ sent on the rotary table 3.

Therefore, the one-sided discs A and A'after screen printing have concentric circles around the center hole and the outermost periphery of the disc, which are not coated with the adhesive, so that they will be described later. The disk suction portion 9 of 8 is brought into contact with the ring-shaped portion to which the adhesive is not applied, so that the single-sided disk is vacuum-sucked and lifted. In addition, the ring-shaped part to which this adhesive is not applied,
The adhesive applied when the discs are bonded together in the later-described pressure-bonding step serves as a flank when the discs stick out in the inner and outer peripheral directions by the pressure-bonding force, and prevents the adhesive from sticking out from the inner and outer peripheries of the disc.

The UV adhesive may be, for example, "OM-1015" (viscosity 1.
0 Pa.s) ”or the like is used. Examples of the cationically polymerizable UV-curable adhesive include "Adeka Optomer KRX726-1" (viscosity 0.
17 Pa.s) ”or the like is used.

Further, the UV (ultraviolet) of the turntable 3
The UV irradiator 7 is provided at the irradiation position P ₅ . The UV irradiator 7 irradiates the adhesive applied to the surfaces of the single-sided disks A and A ′ with ultraviolet rays. When the applied adhesive is a UV adhesive, this ultraviolet irradiation imparts adhesiveness as an adhesive, and when the applied adhesive is a cationically polymerizable ultraviolet curable adhesive, this ultraviolet light is applied. Irradiation gives the initiation of the curing reaction.

The attracting arm 8 is a robot which attracts and lifts the single-sided discs A and A'at the disc ejecting position P ₆ of the rotary table 3 by the disc attracting portion 9 at the tip thereof and transfers them to the laminating portion 10. is there. The single-sided discs A and A ′ transferred to the laminating section 10 are each flattened by a straightening mechanism which will be described later, and then pressure-bonded to each other in the state of being straightened to complete a single disc. It The completed disc D is adsorbed by the suction cup 38a of the disc discharge arm 38, transferred to the belt conveyor 1 again, and transferred to the subsequent process.

The position P of the rotary table 3
Positions ₃ and P ₄ are constant in order to smooth the unevenness of the surface, referred to as the screen mesh, of the adhesive applied to the surface of the single-sided disks A and A ′ by the screen printing machine 6 by the action of gravity and surface tension. It is a waiting position to wait for a time.

FIG. 3 shows a specific structure of the disk suction portion 9 attached to the tip of the suction arm 8. In the figure, 11 is the center hole 12 of the disks A and A '.
A ring-shaped part around which the adhesive is not applied (eg φ
A circular inner suction wall formed so as to come into contact with a 37 mm position), and a circular inner suction wall 13 formed so as to come into contact with a ring-shaped portion (for example, φ296 mm position) to which the adhesive is not applied near the outer circumferences of the disks A and A ′. The outer adsorption wall 14 is a gas passage for evacuation. O-rings 15 and 16 are fitted to the tips of the inner suction wall 11 and the outer suction wall 13, respectively, in order to ensure airtightness when the single-sided disks A, A are vacuum-sucked.

The suction arm 8 can be horizontally rotated by a rotation mechanism (not shown), and the disk suction portion 9 can be vertically inverted and raised / lowered by a reversal / vertical movement mechanism (not shown). Has been done. When the suction arm 8 is rotated to the disc ejection position P ₆ of the rotary table 3, the disc suction portion 9 is lowered so as to come into contact with the one-sided discs A and A ′ as shown in FIG. Then, in this state, the air in the portion surrounded by the inner and outer adsorption walls 11 and 13 is sucked through the gas passage 14 by a vacuum pump (not shown). As a result, the disks A and A'are vacuum-sucked to the disk suction portion 9 in the state shown by the dotted line in the figure. In this way, when the single-sided disks A and A ′ are vacuum-adsorbed,
The suction arm 8 rotates toward the bonding section 10 and transfers the sucked single-sided disks A and A ′ onto the suction tables 17 and 18 above and below the bonding section 10 (FIG. 4 described later)).

FIG. 4 shows a specific structure of the bonding section 10. In the case of this embodiment, the bonding section 10 is
It is composed of a pair of upper and lower suction tables 17 and 18. The lower suction table 17 is provided with a porous member 19 having air permeability inside thereof, and the whole is fixed on a base 20. The surface of the porous member 19 is formed flat, and this surface constitutes the vacuum suction surface 21 of the disk. A gas passage 22 is formed between the lower adsorption table 17 and the porous member 19. The porous member 19 is, for example, "plastic sintered body (flatness 1 μm, pore diameter × number: φ0.1 μm × 5100 / cm ² , porosity 42%, trifluorinated ethylene chloride resin) sold by CKD Co., Ltd. ] Is used.

A stopper pin 23 is provided at an appropriate position on the upper surface of the base 20 to regulate the stop position of the upper suction table 18 which descends when the disks are bonded together. The stopper pin 23 is a pressure cylinder. 24
The pin position can be adjusted freely. Further, a vacuum pump 26 is connected to the base 20 through a gas passage 25, so that vacuum suction is performed at the time of disc bonding, which will be described later. 27
Is a center pin for aligning the center position of the one-sided disk to be placed, and 37 is a packing for contacting the lower end of a vacuum chamber 33 described later to keep the inside airtight.

On the other hand, the upper suction table 18 paired with the lower suction table 17 is fixed downward to the lower surface of a piston block 29 which is movable in the vertical direction by a pressure cylinder 28, and inside thereof is fixed. Porous member 30 having the same air permeability as the lower adsorption table 17
Has been laid. The surface of this porous member 30 is formed flat, and this surface constitutes the vacuum suction surface 31 of the disk. A gas passage 32 is formed between the upper adsorption table 18 and the porous member 30.

In the piston block 29, a vacuum chamber 33 for enclosing the entire upper suction table 18 is provided with a bushing 3
4, which are slidably attached by O-rings 35, and the air in the vacuum chamber 33 is vacuum-sucked by the vacuum pump 26 of the lower suction table 17 when the one-sided disks A, A'to be described later are attached. The inside of the vacuum chamber 33 can be adjusted to a predetermined negative pressure. Reference numeral 36 is a center pin hole that makes a pair with the center pin 27.

FIG. 5 shows a method of placing the single-sided disk A on the lower suction table 17 of the bonding section 10. Now, when the disc suction portion 9 of the suction arm 8 that has sucked the single-sided disc A reaches just above the lower suction table 17 of the bonding portion 10 as shown in FIG. 5, and is lowered until it contacts the vacuum suction surface 21. The vacuum suction of the gas passage 14 of the disc suction portion 9 is stopped and the suction of the one-sided disc A is released, and at the same time, the one-sided disc A is vacuum sucked through the gas passage 22 of the lower suction table 17 and the porous member 19. The entire lower surface of the opened single-sided disk A is vacuum-sucked to the vacuum suction surface 21 of the porous member 19. Then, after that, about 2 kg / cm ² of compressed air is fed from the gas passage 14 of the disc adsorption portion 9, so that the single-sided disc A adsorbed to the lower adsorption table 17 by the pressure difference is indicated by the dotted line in the figure. As shown, straighten it into a flat state and adsorb it.

Similarly, the other one-sided disk A '
As for the above, the disk suction portion 9 of the suction arm 8 is also vacuum-sucked to the vacuum suction surface 31 (see FIG. 4) of the upper suction table 18. In this case, as is clear from FIG.
Since the vacuum suction surface 31 of the upper suction table 18 faces downward, the disk suction portion 9 of the suction arm 8 is
The work is performed in the same manner as in FIG. 5 by reversing the top and bottom by an upside down reversing mechanism (not shown) so that the top and bottom are reversed.

As described above, the single-sided disks A and A'transferred by the suction arm 8 are corrected to be completely flat, respectively, and the lower suction table 17 and the upper suction table 1 are arranged.
After vacuum adsorption to the disk 8, two single-sided disks A and A'are attached to each other as shown in FIG.

That is, in FIG. 1, when the upper suction table 18 is lowered by the pressure cylinder 28 together with the vacuum chamber 33, the lower end of the vacuum chamber 33 comes into contact with the packing 37 of the base 20 of the lower suction table 17, and a vacuum is generated. The tank 33 stops at this position. Then, only the upper suction table 18 continues to descend, and when the gap between the upper suction table 18 and the one-sided disk A placed on the lower suction table 17 becomes about 20 μm, the piston block 29 is adjusted in position by the pressure cylinder 24. The upper suction table 18 is temporarily stopped by coming into contact with the stopper pin 23.

After the upper suction table 18 is stopped, the air in the space partitioned by the vacuum chamber 33 and the base 20 is evacuated by the vacuum pump 26, and the internal pressures of the upper and lower suction tables 17, 18 are one-sided disks. When the suction pressure becomes the same, the upper suction table 18 and the stopper pin 23 are further lowered by the pressure cylinders 28 and 24, and a pair of vacuum suction surfaces 21 and 31 of the upper and lower suction tables 17 and 18 are vacuum-sucked. The single-sided disks A and A'are brought into contact with each other.

Then, from this state, pressure is further applied by the pressure cylinder 28 to press the single-sided disks A and A ', and they are bonded to one disk. The pressure applied at the time of bonding is, for example, about 3 kg / cm ^{2 as} the pressure on the disk surface. During pressurization by the pressure cylinder 28, the gas passages 22 of the upper and lower adsorption tables 17 and 18,
If the compressed air of about 32 to 2 kg / cm ² is fed, the flatness of the single-sided disks A and A ′ is further improved.

As described above, the pair of single-sided disks A,
When A's are attached to each other, the upper suction table 18 is pulled upward by the pressure cylinder 28 to form the completed disc D. After that, the ejection arm 38 is rotated to the bonding section 10, and the completed disc D is adsorbed by the suction cup 38a at its tip, transferred to the belt conveyor 1 and transferred to the subsequent process.

A disk manufactured according to the above embodiment,
Table 1 shows a comparative example of the warped state of the disc manufactured by the conventional method of FIG. This comparative example has a diameter of 120.
In the case of a DVD (digital video disk) of mm, the warp angle θ in the table is an angle formed by a normal line standing on the disk surface and a vertical line at each radial position. Therefore, the smaller the warp angle θ, the smaller the warp of the disk. As is clear from Table 1, the warp of the disk is smaller in the present invention than in the conventional example.

[0038]

[Table 1]

In the above embodiment, the adhesive was printed and applied by the screen printing machine 6, but instead of the screen printing machine 6, the roll coater 3 as shown in FIG.
It is also possible to use 9. In FIG. 6, 40 is a doctor (gap forming member) for supplying the hot melt adhesive 42 supplied to the main roll 41 with a constant film thickness, and 43 is the hot melt adhesive 42 supplied to the main roll 41. A transfer roll for transferring to the single-sided disks A and A '.

When the roll coater 39 is used as an adhesive coating device for the present invention, the surface of the transfer roll 43 is an area (φ40 in the above embodiment) to which the adhesive of the single-sided disks A and A'is to be coated. (A range of ˜295 mm), and a relief plate is provided at a position corresponding to the area. Single-sided disc A,
A ′ is placed on the moving table 44, and the transfer roll 43
It is sent in the direction of the arrow in synchronization with the rotation of. As a result, the main roll 41 transferred to the letterpress portion of the transfer roll 43
Hot melt adhesive 42 from single-sided disc A, A '
It will be applied only to the adhesive application area.

In addition to the above-mentioned coating method, a protective film is previously formed by screen printing or tampo printing only on the area of the single-sided disk to which the adhesive is to be applied, whereby only the adhesive-applied area is applied to other disks. Keep the height higher than the surface, or make the adhesive-coated area thicker than the other parts from the beginning when injection molding a single-sided disk, so that only the adhesive-coated area is higher than the other disk surfaces. Various methods can be adopted, such as a storage method.

In the embodiment described above, the single-sided disk A,
Although the adhesive is applied to both A ', the adhesive may be applied to only one of the single-sided disks A or A'. Further, the adhesive is not limited to the above-mentioned UV pressure-sensitive adhesive, cation-polymerizable UV-curable adhesive and hot-melt adhesive, and it goes without saying that other adhesives can be used.

In the above embodiment, the optical video disc is used as an example of the pasted disc, but the present invention is not limited to this, and at least two single-sided discs are pasted together to form one disc. Any type of disc can be applied.

[0044]

As described above, according to the present invention,
The bonded finished discs do not warp or twist, and high-quality bonded discs can be stably and mass-produced. Further, since the generation of defective disks with large warpage and twisting is reduced, the yield of disk manufacturing can be improved and the production efficiency can be improved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a disc bonding method according to an embodiment.

FIG. 2 is a schematic plan view of the overall configuration of the embodiment.

FIG. 3 is a schematic vertical sectional view of a suction portion of a suction arm according to an embodiment.

FIG. 4 is a schematic vertical cross-sectional view of a bonded portion in an example.

FIG. 5 is an explanatory diagram of a method for transferring a single-sided disk to a suction table in the embodiment.

FIG. 6 is a schematic vertical cross-sectional view of a roll coater as another example of the adhesive applying device for the present invention.

FIG. 7 is an explanatory diagram of a pasting process in conventional disc manufacturing.

[Explanation of symbols]

 A, A'a pair of single-sided discs 1 belt conveyor 2 laminating disc manufacturing device 3 rotary table 6 screen printer 7 UV irradiator 8 adsorption arm 9 disc adsorption part 10 laminating part 11 inner adsorption wall 13 outer adsorption wall 14 gas passage 17 Lower adsorption table 18 Upper adsorption table 19 Porous member 21 Vacuum adsorption surface 22 Gas passage 23 Stopper pin 24 Pressure cylinder 25 Gas passage 26 Vacuum pump 28 Pressure cylinder 29 Piston block 30 Porous member 31 Vacuum adsorption surface 32 Gas passage 33 Vacuum chamber

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location B32B 15/08 B32B 15/08 K // B29L 17:00

Claims (5)

[Claims] 1. An adhesive is applied to at least one of the pair of single-sided disks to be bonded so that there is a ring-shaped portion to which no adhesive is applied, and then the pair of the single-sided disks are bonded. The single-sided disks are vacuum-sucked to the vacuum suction surfaces of the suction tables to correct the warp and twist of each disk surface, and the bonded surfaces of the pair of single-sided disks are crimped while the warp and twist are corrected. A method for manufacturing a bonded disc, which comprises bonding the layers together. 2. A protective film to be applied on the optical reflection film of a single-sided disc is applied only to a portion to which an adhesive is applied, and a step due to the thickness of the protective film applies the adhesive to the outer peripheral portion and the inner peripheral portion of the single-sided disc. The method for manufacturing a bonded disk according to claim 1, wherein a ring-shaped portion which is not applied is formed. 3. A step is provided so that the thickness of the outer peripheral portion and the inner peripheral portion of the single-sided disk is smaller than that of the portion to which the adhesive is applied. The method for manufacturing a bonded disk according to claim 1, wherein a ring-shaped portion to which no adhesive is applied is formed. 4. Adhesive applying means for applying an adhesive to at least one of the pair of single-sided disks to be bonded so that there is a ring-shaped portion to which no adhesive is applied at the outer peripheral portion and the inner peripheral portion thereof. , A disk transfer means for bringing the disk suction part of the suction arm into contact with the outer peripheral part and the inner peripheral part of the single-sided disc, which are not coated with the adhesive, for vacuum suction, and for transferring to the suction table of the disc bonding means, The pair of single-sided disks transferred to the table are vacuum-sucked from the back surface side to be vacuum-sucked on the flat vacuum suction surface of the suction table, thereby correcting the warp and twist of each single-sided disk, An apparatus for manufacturing a bonded disk, comprising: a disk bonding means for bonding a pair of single-sided disks by pressure bonding. 5. The vacuum suction surface of the suction table of the disk laminating means is made of a porous member, the disk is vacuum-sucked from the back surface of the porous member, and when the pair of single-sided disks are pressure-bonded, the porous 5. The bonded disk manufacturing apparatus according to claim 4, wherein compressed air is blown onto the entire surface of the disk through the quality member to press the entire surface of the disk with a uniform force.