JPH01279480A - Manufacture of disk cassette - Google Patents

Abstract

PURPOSE:To prevent fall-off of minute fiber from liner fiber and occurrence of resin powder from a cassette half by providing a magnetic substance to the cassette half so as to apply high frequency welding the cassette halves. CONSTITUTION:A cleaning sheet made of a liner fiber member is lined to the cassette halves 1, 2 made of a resin member and the halves 1, 2 are welded while a disk medium is clipped between the sheets. A magnetic substance 13 is provided near the welded part of the half 1 and induction heating is caused by a high frequency, the vicinity of the welded parts of the halves 1, 2 is softened and the halves 1, 2 are subject to high frequency welding. Thus, no vibration is caused different from the case with ultrasonic wave welding and fallen off minute fiber from linear fibers or occurrence of resin powder of the cassette halves is prevented to form a disk cassette with high reliability.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is applicable to writing, reading, and erasing of disk media (plate-shaped information recording media) such as floppy disks, 3.5-inch microfloppy disks, optical disks, and magnetic disks. The present invention relates to a method for manufacturing a disk cassette that can significantly reduce signal dropout during (including) and produce error-free, high-quality disk cassettes.

(Prior art and its problems) Disk cassettes used as storage media for computers, etc. are becoming more dense as computer capacity increases, and for this reason, recording disk media are becoming more dense than ever before with microscopic particles that adhere to the surface. The presence of dust (liner separated fibers, resin powder, airborne dust, etc.) has become a problem.

In other words, the general structure of a disk cassette is that a cleaning sheet for removing dust etc. adhering to the media surface is adhered to the inner surface of a pair of upper and lower synthetic resin halves so that it is always in contact with one and/or both sides of the media. are distributed.

To prevent dust from adhering to or sticking to the media surface, the pair of upper and lower synthetic resin halves are equipped with a shutter that opens only when the head window is in use, and a peripheral wall with a diameter one size larger than the outer circumference of the media. Although various measures have been taken to prevent dust from entering from the outside as much as possible, such as by installing protective walls inside the half, cleaning sheets are required to incorporate media into the half to create a disk cassette. A pair of upper and lower halves that are glued to the inner surface must be welded together. Generally, the above-mentioned cleaning sheet is made from a nonwoven fabric made of natural or synthetic fibers such as PP/rayon mixed fiber, PET/rayon mixed fiber, PETMII fiber, acrylic fiber, etc., and this nonwoven fabric has a length of 10 to 100 tm. It is made by intertwining fibers, or by thermally bonding with meltable resin such as PP or PET, or by pressing with a rubber adhesive such as SBR or NBR so that the fibers do not separate during use. However, with this method, minute fibers and resin powder tend to peel off and fall off due to vibrations, etc., which causes contamination of the media.

That is, the method that has been generally used to weld a pair of upper and lower halves is the ultrasonic welding method, and as shown in the conceptual diagram in which the welded part is enlarged and emphasized in Fig. 3, the horn a of the welding machine is By vibrating at ~40 kHz, the upper half b to be welded is also periodically vibrated vertically at ~40 kHz, generating frictional heat at the interface between welding bosses c and d of both the upper and lower halves. , a method in which the upper and lower halves are melted and integrated. Therefore, during the processing when assembling the disk cassette, vibrations are also transmitted to the cleaning sheet e glued to the inner surfaces of the upper and lower halves, and the nonwoven fabric that makes up this sheet contains minute fibers (lint) and resin generated by friction. The powder f fell on the 8 sides of the mesh, resulting in contamination.

Although attempts have been made to select materials for the sheet that are less susceptible to fiber detachment, such materials often have poor cushioning properties and, therefore, poor cleaning effectiveness.
Particles generated when the surface layer of the medium is scraped off by contact with the recording/reproducing head could not be completely removed.

On the other hand, another method has been proposed in which the upper and lower halves are integrated at the welded part using an adhesive, but if the adhesive is organic solvent-based, there is a risk that it may have a negative effect on the media surface or deform the half. In most cases, adhesive viscosity control is required for non-organic solvent based adhesives.

There were complicated operations such as exhaust treatment and liquid dripping, and there were also problems with process control.

Furthermore, as a method to remove dust that has fallen onto the media, methods have been proposed such as blowing clean air onto the media surface or directly contacting the media surface from the outside through the media head window, but these methods require additional manufacturing steps. This had the disadvantage of increasing production costs.

(Means for Solving the Problems) As a result of various studies by the present inventors regarding means for integrating the upper and lower halves in place of the above-mentioned ultrasonic welding method, we found that, with the high-frequency welding method, minute particles from the nonwoven fabric liner during the welding process are The present inventors have discovered a manufacturing method that does not cause fibers to fall off or generate resin powder, thereby reducing the occurrence of errors during reading and writing, and has completed the present invention.

The present invention is applied to the inner surface of a pair of upper and lower synthetic resin halves.

In a disk cassette in which a cleaning sheet is attached inside each sheet, a disk medium is accommodated between the sheets, and a pair of upper and lower synthetic resin halves are welded at a welded portion, the welded portion and/or the welded portion of the pair of synthetic resin halves are The gist of this method is to provide a magnetic material near the welded part and weld the welded part by high-frequency welding.

To explain this, the high-frequency welding method has conventionally been mainly used for welding soft vinyl chloride sheets, and in this case welding uses dielectric heating of the soft vinyl chloride sheet to reach the softening temperature of the material from the inside. This is a method of welding at a high height, and in the case of hard vinyl chloride sheets, advanced and special techniques are required, and the sheet thickness is 0.3 mm.
It has the disadvantage that the following and its scope of application are limited:

Therefore, in the method of the present invention, A[
For resins other than PvC, such as 3S resin and PS, a magnetic material is provided on at least one of the welding parts of the upper and lower halves in order to produce this dielectric effect and weld the resins, such as 3S resin and PS. Heat is generated by induction heating at ~50 MHz, and the resin in the welded part of the half in contact with the magnetic material is heated to a softening temperature, thereby uniformly softening and welding the welded part. Therefore, welding can be performed without applying vibrations to the halves as in ultrasonic welding.
It is possible to prevent minute fibers from falling off from the liner fibers and generation and falling of resin powder from the half, and as a result, errors can be reduced.

Hereinafter, details of the present invention will be explained based on the accompanying drawings. FIG. 1 is an exploded perspective view showing an example of a disk cassette to which the method of the present invention is applied, and in the figure, 1.2 is a pair of upper and lower synthetic resin halves forming the outer shell of the disk cassette; 3. Reference numeral 4 indicates a pair of upper and lower cleaning sheets made of non-woven fabric, each of which is pasted on the inner surface of the half 1.2, 5 indicates a disk medium disposed between these sheets, and 6
A core bar (not normally used in floppy disks) is glued to the center hole, and a center hole 7 for rotating the disk medium is provided in the center. 8 are welding bosses provided on the inner surface of half 1.2, preferably at the four corners, for joining the two halves.

Reference numeral 9 indicates a driving port bored in the center of the lower half 2, IO indicates a head window, and 11 indicates a rib provided in a discontinuous circle on the inner surface of the half 1.2 for regulating the position of the liner. , 12 are glue lids for bringing the cleaning sheet 4 into contact with the disk media to provide a cleaning effect. As shown in FIG. 2(a), which is a conceptual diagram showing an enlarged and emphasized welded portion, a stainless steel piece 13 that has been subjected to a rust-proofing treatment is embedded in the welding boss 8 .

Note that the magnetic piece embedded in order to cause the induction heating phenomenon is desirably a magnetic body with a diameter of about 0.8 to 1.2 φ. If it is smaller than this, the amount of heat generated is too small to sufficiently raise the resin to the softening temperature, and if it is larger than this, a high current from the outside is required for induction heating. arise. In the present invention, when welding over a wide area, the half, especially the welding part, may be composed of a resin mixed with a magnetic material, but in this case, if the internal media is magnetic media, the half is magnetic Since there is a risk that the welding may adversely affect the disk media and destroy the recorded information, care should be taken to achieve partial welding as much as possible.

The difference between Fig. 2(b) and Fig. 2(a) is that Fig. 2(a)
) shows the magnetic material 13 embedded in the boss 8, whereas in FIG. Figure 2 (c
), the boss itself is made of a magnetic material by two-color injection molding, and FIG. 2(d) shows a case in which the magnetic material is fitted from the outside of the half 1.

The magnetic materials used in the present invention include iron, cobalt, nickel, or alloys of ferromagnetic or weakly magnetic materials based on these materials, as well as single metals or alloy powders of these materials in thermoplastic elastomers (polyester, polyurethane, etc.). It may be a ferromagnetic or weakly magnetic material obtained by mixing with a thermoplastic (ABS, PVC, olefin, etc.) or a thermoplastic (ABS, PVC, olefin, etc.). Of course, the surface of an ordinary plastic molded body may be partially or completely coated or laminated with the above-mentioned ferromagnetic or weakly magnetic substance.

Further, in the above invention, the welded portion is the boss 8, but as long as the welding strength of the upper and lower halves is sufficient, this can be applied to a part or the entire circumference of the outer edge 14 of the half, or a part or the entire circumference of the rib 11. Furthermore, in Figures 2 (a) to (d), only the upper half is shown with the magnetic material provided, but this may be applied only to the lower half or to both the upper and lower halves. may be provided. In addition, 20 in the figure is a high frequency welding machine.

(Example) Regarding the disk cassette shown in FIG.
．． A half is used in which 5US (403) of 5nn+, diameter 1.0mm is embedded in the bosses at the four corners of the upper half. )
Welding was carried out by ultrasonic welding and high frequency welding under the conditions shown in Table 1 below.

Table 1 The results of investigating the electromagnetic conversion characteristics of the welded and integrated products under the above conditions are shown in Table 2. The yield of ultrasonic welding was 75%, while that of high-frequency welding was 95%, an improvement of 20%, clearly eliminating errors caused by minute fibers and resin powder detached from the liner. A reduction was seen.

Table 2 Measurement conditions are as per JI S Extra pulse: 15% or more.

In addition, the ranks ■～■ are as follows: Rank ■: Spec clear on both sides, missing level 70% or higher on both sides.

Rank ■: Spec clear on both sides, missing level 70-50% on both sides.

n ■: Specification clear on O side, missing level 70% or more on side 0, NG on side 1.

+1 TV　　20 side specs cleared.

Missing level: 50% or more on the O side.

1st side NG.

JJ V H Both sides have poor specs.

(Effects of the Invention) According to the present invention, there are no synthetic resin fine powders generated due to vibrations during high-frequency welding or fine fibers detached from the cleaning sheet, so that recording and reproduction on disk media is not possible. There is no dust adhering to the disc media, which causes dropouts during storage, and therefore high-quality disc cassettes can be manufactured without errors when inputting and outputting information.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view showing the configuration of a disk cassette to which the method of the present invention is applied, and FIGS.
d) is a conceptual cross-sectional view with the welded part enlarged and emphasized, showing an embodiment in which the positions of the magnetic bodies of the upper and lower halves used in the present invention are changed; FIG. FIG. (Explanation of main symbols) 1.2...Synthetic resin half, 3.4...Cleaning sheet, 5...Disc media. 13...Magnetic material. Figure 1 Figure 2 (a), 20 (b) (C)

Claims (1)

[Claims] In a disk cassette, a cleaning sheet is pasted on the inner surface of each of a pair of upper and lower synthetic resin halves, a disk medium is accommodated between the sheets, and the pair of upper and lower synthetic resin halves are welded at a welding part. A method for manufacturing a magnetic disk cassette, comprising: providing a magnetic material at and/or near a welded portion of a synthetic resin half, and welding the welded portion by high-frequency welding.