JPH0576898B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is applicable to the manufacture of so-called air sandwich type optical disks, in which two optical disks are connected via two annular joint surfaces on the circumference and the outer circumference. It relates to an ultrasonic horn used for laminating each other or for laminating a single optical disk to a dummy disk without a recording layer.

(Background of the Invention) Optical discs that record information by making holes in the recording material layer or changing its reflectance by laser beam irradiation generally consist of two optical discs pasted together with an air layer in between. It is usually used in a so-called air sander beach type structure.

There are two main ways to bond two optical disks together.
One of them is a coating method using an adhesive such as a pressure sensitive adhesive or an ultraviolet curable resin, and the other is an ultrasonic bonding method. The present invention relates to the latter.

Although the ultrasonic bonding method is superior in operability and productivity compared to the coating method, there are many problems that must be solved when air sandwich type optical disks are manufactured industrially. In particular, (1) the amount of eccentricity is required to be about 20 microns or less, so the two optical disks must be bonded together with their centers perfectly aligned. This is generally accomplished by fitting the two disks onto a centering spindle and welding them together, but the non-vertical forces applied by the ultrasonic horn during welding can cause the two disks to shift laterally relative to each other. . (2) Due to non-uniform or abnormal ultrasonic energy, the birefringence (retardation) of the resin substrate changes, the recording film peels off from the substrate, or the recording film changes in quality. (3) Unable to withstand rotation speeds of 1800rpm or higher due to insufficient strength due to poor adhesion. (4) When two optical disks are pasted together, each disk bends, that is, curves.

These problems cannot be solved simply by adapting conventional ultrasonic welding methods for plastic parts.

(Prior art) It is already well known that two disks are bonded together using ultrasonic waves (for example, Japanese Patent Application Laid-open No. 14342/1983,
(Japanese Patent Publication No. 101738/1983). However, the previously known methods and devices merely apply techniques used for ultrasonic welding of plastic materials to the lamination of optical disks. In Japanese Patent Application Laid-Open No. 129749/1983, the bulge of each disk is prevented by limiting the size and shape of the protrusions that melt during ultrasonic welding, that is, the energy director. However, there is no particular description of the ultrasonic horn itself.

OBJECTS OF THE INVENTION It is an object of the present invention to provide an improved ultrasonic horn for use in precision optical components, particularly for laminating two optical disks. In particular, an object of the present invention is to provide an ultrasonic horn that can solve each of the above problems.

(Structure of the Invention) The present invention provides a first disk having a recording film for recording and reproducing information using light, and a second disk with or without a recording film with the film on the inside.
In an ultrasonic horn used for welding an air sandwich type optical disk, which is used to bond the disk to each other by ultrasonic welding via the circumferential annular joint and the outer circumferential annular joint, A deaeration hole is provided in the ultrasonic horn body between the processed surface for circumferential annular joining and the processed surface for outer circumferential annular joining to communicate the space defined by the ultrasonic horn and the optical disk surface with outside air during the welding operation. The present invention relates to an ultrasonic horn characterized by the following:

Various kinds of recording films such as Te-based and organic-based recording films are well known for the first disk. The second disk may be a recording disk having the same or different recording film as the first disk, or it may be a mere cover disk without a recording film, a so-called dummy disk. In order to provide a space between the first and second disks, it is necessary to insert spacers into the inner and/or outer circumferences of both disks. This spacer may be an annular projection integrally molded on the first disk and/or the second disk, or may be formed separately from the disk and integrated with the disk during ultrasonic welding. The structure of these so-called air sander bench type optical disks is well known and is not the purpose of the present invention, so details thereof will be omitted.

The feature of the present invention lies in the shape of the ultrasonic horn, in particular, the ultrasonic horn body between the inner and outer annular machined surfaces where the ultrasonic horn contacts the disk is partitioned by the ultrasonic horn body and the surface of the optical disk. The point is that a vent hole is formed to communicate the space with the outside air.

The part where the ultrasonic horn contacts the disk, that is, the machined surface, needs to be annular to match the area to be welded, but the outer shape of the disk body may have either a circular or square cross section. ,
According to the inventor's experiments, an ultrasonic horn having a square cross section gives better results. The reason for this is currently unknown.

Generally, the design of ultrasonic welding horns is based on experience, and the generated energy is basically taken into consideration. This generated energy E is the product of the output amplitude A of the applied ultrasonic wave, the pressing force F, the pressing time T, and the cos θ of the angle θ formed by the above F and A (E = A・F・T・cos θ) It is expressed as

Horns used for welding plastics are usually designed to resonate in a longitudinal mode of 20KHz±50Hz, with the node plane centered on the horn. In addition, aluminum (7075 aluminum), titanium (6AL 4V), etc. are used as the horn material. The material and dimensions of the horn can be appropriately selected by those skilled in the art based on experience and theory.

The present invention is characterized by the shape of the ultrasonic horn. That is, the present invention is characterized in that the space defined by the horn body and the disk surface is communicated with the outside air.

By doing this, the problems of the conventional method,
Namely (1) bulging or bending of the disk surface; (2)
(3) Bad adhesion problems caused by abnormal vibrations on the recording film and substrate have all been resolved, and the problem of the welded disk and horn sticking together due to high vacuum has also been solved. No more practical problems. In this case, forcibly separating the disk will have a serious adverse effect on the recording film and substrate.

The present invention will be described below with reference to the drawings.

First, the conventional method will be explained using FIG. The two disks 3 and 4, which are ultrasonically welded together, are placed on the lower pedestal 2 while being fitted onto a centering pin 6. An annular rib is provided on the circumference and outer circumference of at least one of the disks 3 and 4. A separate spacer ring can also be used instead of this rib.

A minute protrusion called an energy director is formed on at least one of the annular ribs, and the energy director is activated by ultrasonic energy applied via the processed surfaces 10 and 11 of the ultrasonic horn body 1. Melting starts from a certain point.

The disadvantage of this type of ultrasonic horn is that air is trapped in the space 7 defined between the disk 3 and the horn body 1, causing the disk to bend. This is the point where an abnormal force is applied to the disk due to the pressure of the disk, resulting in uneven adhesion.

In order to eliminate these drawbacks, the present invention communicates the space 7 with the outside air.

The present invention will be explained below with reference to FIGS. 1 and 3. In each drawing, members corresponding to those in FIG. 2 are given the same symbols.

In order to communicate the space 7 with the outside air, the first and third
In the illustrated embodiment, a degassing hole 20 is formed in the horn body 1 and communicates with the space 7, and this degassing hole 20 communicates with a slot 21 normally provided in the ultrasonic horn body 1. This slot 2
The shape, number, and dimensions of 1 can be appropriately selected by those skilled in the art based on known design standards for the horn body.

Although the number of deaeration holes 20 is four in FIGS. 1 and 3, it is not limited to this.

Further, the surface of the horn body that partitions the space 7 does not have to be flat as shown in FIGS. 1 and 3, but can also be a curved surface 23 as shown in FIG. 4.

Also, the deaeration hole is not in the horn body 1, but in a slit 2 formed in the machined surface 10, as shown in FIG.
It can also be set to 0'. These slits need to be as narrow as possible, and their number should also be as small as possible.

In the embodiment shown in FIG. 5, the cross-sectional shape of the horn body is square.

The present invention has an extremely simple structure and can solve all the problems of conventional laminated disks.

[Brief explanation of the drawing]

FIG. 1 is a schematic longitudinal cross-sectional view of an ultrasonic horn according to the present invention. FIG. 2 is a longitudinal sectional view showing the main parts of a conventional horn. FIG. 3 is a perspective view of the horn shown in FIG. 1, viewed from below. 4 and 5 are a longitudinal sectional view and a bottom perspective view showing another embodiment of the present invention. (Symbol in the figure), 1: Ultrasonic horn, 10, 1
1: Processed surface, 20: Deaeration hole, 21: Slot.

Claims (1)

[Claims] 1. A disk having a recording film that records and reproduces information using light is attached to another disk with or without a recording film with the film on the inside at a circumferential annular joint and In an ultrasonic horn used for welding air sandwich type optical disks, which are used to bond together by ultrasonic welding via an outer annular joint, the above-mentioned processed surface for inner annular joining and An ultrasonic device characterized in that a deaeration hole is formed in the ultrasonic horn body between the outer circumferential annular joining surface and the processing surface for communicating with outside air the space defined by the ultrasonic horn and the optical disk surface during the welding operation. Horn. 2. The ultrasonic horn according to claim 1, wherein the ultrasonic horn has a cylindrical cross section. 3. The ultrasonic horn according to claim 1, wherein the cross section of the ultrasonic horn is a regular square. 4. The ultrasonic horn according to any one of claims 1 to 3, characterized in that it has a longitudinal slit, and the deaeration hole communicates with the slit.