Conventionally, in connection with a two optical disk pasting apparatus and a method for pasting the same, various types of technologies have been developed and proposed, wherein a chamber provided so as to enclose a pasting apparatus itself is made vacuum.
For example, the first technique disclosed in Japanese Laid-open Patent Publication No. 273213 of 1996 and the second technique disclosed in Japanese Laid-open Patent Publication No. 198720-1997 are listed. Hereinafter, a detailed description is given of these conventional arts.
The first technique (Japanese Laid-open Patent Publication No. 273213 of 1996) shown in FIG. 7 is an art developed so as not to thicken the outer circumference of a disk due to a protection film.
That is, in a method and an apparatus 20 for producing pasted disks which the adhered surfaces of a pair of one-sided disks 21 and 22 are butted to each other and pressure-fitted after forming a projection film on a reflection film of the pit surface of the pair of one-sided disks 21 and 22 to be pasted together and coating an adhesive agent to the pasting surface of at least one of the one-sided disks, the space 28 in a vacuum chamber 26 is vacuumed by a vacuum pump (not illustrated), using a vacuum tank having such a size so as to cover pressure-fitting tables 25 and 26a to make the inside of the vacuum chamber 28 vacuum. Thereafter, by causing the pressure-fitting table 24 secured to a rod 29 to fall down, the outer circumferential portion 27 of the disks 21 and 22 is first pressure-fitted by ring-like projections 25 and 26 formed on the pressing surface of the upper and lower pressure-fitting tables 23 and 24, and next, the entire surfaces of the disks 21 and 22 are adhered to each other.
The second technique (Japanese Laid-open Patent Publication No. 198720-1997) shown in FIG. 8 is an art developed for an object for more effectively removing air bubbles which may be mixed in an -adhesive agent of the pasted disks 31 or in the disk 31.
That is, in the pasting method of an overlapped disk 31, the overlapped disk 31 placed between an upper press plate 37 secured at an axial portion 39 and a lower press plate 38 is positioned in closed space 33 formed by covering a chamber 32 in a compression device 30, wherein when vacuuming the closed space 33 by a vacuuming tube 34, O rings 35 which seal the chamber 32 are deformed by pressure given from the outside to the rigid chamber 32, which forms the closed space 33, and the overlapped disk 31 is compressed equivalent to a decrease in the sealing interval 36 in line with the deformation of the O rings 35. Thereby, air suction resulting from the vacuuming is to suck air bubbles in the adhesive agent of the overlapped disk 31.
In addition, the third technique disclosed in Japanese Laid-open patent publication No. 245331 of 1991, which is illustrated in FIG. 9, is an art developed in order to exclude air bubbles in the adhesive agent, devise so as to make the thickness of the adhesive agent uniform, and maintain the flatness of the disks 43 and 44 in a good state.
That is, the technique is an art in which an adhesive agent is coated to at least one of a pair of disks 43 and 44, the pair of disks 43 and 44 are faced to each other so that the surface on which the adhesive agent is coated comes inside, and at least one of the disks 44 is deformed by warping so that the center portion is swelled toward the disk 43 side. The pair of disks 43 and 44 are adhered to each other from the center portion to the outer circumferential side one after another. Accordingly, the pair of disks 43 and 44 cemented at their entire surfaces are compressed and pasted to each other.
However, the abovementioned conventional arts are inherently bound with the following problems and shortcomings. That is, in the first and second conventional arts, since vacuum chambers 26 and 32 having a greater capacity such that they can cover the disk plate are employed, the device itself becomes large-scaled, and the production cost is increased. Further, in these types of vacuum chambers 26 and 32, since the inner capacity is great, it is necessary to increase a vacuuming force, wherein a lengthy period of suction (vacuuming) is required in order to get an appointed pressure condition, and the working efficiency is incorrect.
In addition, with the third technology, since a means for warping one disk 44 and pasting the disks 43 and 44 together is employed, a certain effect can be obtained with respect to removal of air between the disks 43 and 44. However, in connection with effective removal of air bubbles mixed in an adhesive agent, removal is not sufficient in that the time required for causing the disk 44 to overlap on the disk 43 is slow, and air sufficiently exists in the surrounding of the disks 43 and 44.
Therefore, it is an object of the invention to provide an optical disk pasting apparatus and a method for pasting optical disks which, in view of effectiveness of a vacuum suction technique in a disk pasting art, can achieve the vacuum suction by a simple construction and can prevent air bubbles from being mixed in an adhesive agent.