JPH0510312Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a magnetic tape cassette for audio, video, etc., using a combined case formed by film transfer molding, and particularly to the position of the parting line of the mold on the side wall of the case.

2. Description of the Related Art Magnetic tape cassettes have been widely used in the past because they have the basic function of recording and reproducing audio, video, and the like. Recently, more and more importance has been placed on not only this basic function, but also the so-called fashion function that makes viewing more enjoyable. For this reason, products with various design improvements are on the market. For example, you can color the case to make it look more beautiful, or attach colorful labels to it. Some models with even more functional design features include larger transparent windows to make it easier to see the magnetic tape inside the case, and various colors applied to the opaque parts of the outer periphery. All of these cases use conventional monochromatic molding techniques. However, when the transparent window section is made larger in this way, the opaque section (not necessarily opaque) on the outer periphery, which corresponds to the so-called frame, becomes narrower by the amount of the enlarged window. When trying to mold and weld the window and outer frame separately using monochrome molding technology, there was almost no problem with the window, but the outer frame became narrower.
Warpage and distortion tend to occur during molding, making molding difficult. Even if it could be molded, its strength is low, so it is prone to deformation such as twisting and distortion during welding, which poses a problem. Therefore, two-color molding technology is usually used when molding such wide window type cases. That is, the window portion and the outer frame portion are molded almost simultaneously in a mold and welded together.

Fig. 2 is a perspective view showing an example of the lower case of the small window type audio/magnetic tape cassette by monochromatic molding as mentioned above. The shape and structure of such a lower case, except for the window portion, are integrally produced by injection molding of plastic, such as polystyrene resin. The mating upper case is also molded in the same way, and when the two cases are overlapped and joined to assemble the combined case, the magnetic tape and functional parts can be stored inside. The base plate 10 of this lower case is a rectangular flat plate, and vertical side walls 12 of approximately the same height protrude from mainly three sides around it.
Also, in the center of the front side, there are four ribs 14 for preventing the tape from coming out, which correspond to the peripheral side walls 12 .
The apexes of the peripheral side walls 12 and prevention ribs 14 are all the same height and coincide with the seam between the fixed and movable sides of the mold (called the parting line). At the center of the base plate 10 is a tape amount confirmation window hole 16, and on the left and right of that are hub axle insertion holes 18. Also, on the front side there is a partition wall 22 which separates the head insertion section 20 of the lower case from the tape storage section, and two tape guide walls 24 connected to it.

FIG. 3 is a perspective view showing an example of a similar lower case of the wide-window type using the two-color molding described above. In the figure, 30 is a substrate of the lower case, which consists of a transparent window section 32 in the center and a frame section 34 forming the outer periphery of the transparent window section 32. 36 is a peripheral side wall around the substrate 30, and 38 is a rib for preventing tape from flying out. or,
Reference numeral 40 indicates a partition wall on the front side thereof, and reference numeral 42 indicates four tape guide walls connected thereto. Even in such a lower case, the heights of the peripheral side wall 36 and the tops of the prevention ribs 38 are all the same, and they also coincide with the parting line of the mold.

Problems that the invention aims to solve: However, if two-color molding is used when molding a wide-window type case, the molding machine is special, so it cannot be used for other purposes, and it is uneconomical. be. Also, since the mold is special and complicated,
It is expensive and troubles are likely to occur. Therefore, manufacturing the case by film transfer molding has been considered. With this film transfer molding, you can freely color the surface of the case except for the part corresponding to the window.
This is because it is possible to print pictures, letters, etc., and thus a wide window type case can be produced using a monochromatic molding machine and a normal mold. FIG. 4 is a schematic view showing the process of forming the lower case by such film transfer molding. In the figure, 50 is a space corresponding to the molded product formed between the stationary mold 52 and the movable mold 54, and 56 is a film set therein on which colors, pictures, characters, etc. are printed. Note that 58 is a space in which the peripheral side walls 12 and 60 correspond to the tape protrusion prevention ribs 14, respectively. When resin is injected from the molding machine into the space 50 through the gate, the printing on the film 56 is transferred to the case surface by the pressure and temperature of the resin, and at the same time the lower case is molded. However, in this way, the tops (tips) of the peripheral side wall 12 of the lower case, the tape protrusion prevention rib 14, etc., which are the seams with the upper case, are aligned with the parting line P ₁ of the mold.
If the molded product is box-shaped, the distance l ₁ from the parting line P ₁ to the printing transfer surface will be large, unlike a thin plate-shaped product. Note that the gate is usually provided near the parting line _P1 in order to improve the introduction of the resin. If this l ₁ is large, the molten resin introduced from the gate will reach the film 5.
Since it takes a long time to cover the entire surface of the film 56, wrinkles and twists are likely to occur in the film 56, which not only distorts the transferred print but also increases the risk of it being cut.

The present invention has been made by focusing on such conventional problems, and by improving the position of the parting line of the mold with respect to the molded product constituting the combined case, distortions and cuts in printing can be avoided. To provide a magnetic tape cassette which has a good finish without any scratches, is inexpensive, and has a large degree of freedom in design.

Means for Solving the Problems Means for achieving the above object will be described below with reference to FIG. 1, which corresponds to an embodiment.

This magnetic tape cassette stores a magnetic tape in a combined case made by film transfer molding, and the peripheral side wall 76, which is the seam of the case,
and the tape protrusion prevention rib 78, etc., are made to be different from the joint _P2 between the fixed side and the movable side of the mold.

Effect The above means works as follows.

If the seam of the combined case by film transfer molding is made different from the seam of the fixed side and the movable side of the mold, the parting line _P2 of the mold will be at the edge of the molded product constituting the case, for example, the peripheral side wall 76. Because it is not at the top of the ridge, but closer to the printing transfer surface, the distance from the parting line _P2 to the printing transfer surface can be reduced. Then, naturally, the distance between the gate near the parting line _P2 and the printing transfer surface becomes smaller. When the distance between the two is reduced in this way, the time for the molten resin introduced through the gate to cover the entire surface of the film is shortened, which prevents the film from wrinkling and twisting, and causing distortions and cuts in the print. This results in a good finish.

Embodiments Hereinafter, embodiments of the present invention will be described based on the accompanying drawings.

FIG. 1 is a perspective view showing an example of the lower case of a wide window type audio/magnetic tape cassette according to an embodiment of the present invention. The lower case shown in this embodiment is almost the same in shape and structure as the conventional example shown in FIG. However, whereas the conventional example adopts two-color molding technology and matches the parting line of the mold to the peripheral side wall and each top of the tape protrusion prevention rib, this example uses film transfer molding and single-color molding. The difference is that a combination of molding techniques is used, and the positions of the parting lines and the tops of the surrounding side walls are made different. Therefore, the features of this embodiment will be mainly described in detail below. In the figure, 70 is a transparent window that widely occupies the center of the lower case board, 72
Reference numeral 74 indicates a hub shaft insertion hole located symmetrically with respect to the window 70, and 74 indicates a portion above and below the window 70 that is widely printed with colors, pictures, characters, etc. by film transfer molding. Reference numeral 76 denotes a peripheral side wall extending mainly around three sides perpendicular to the plane of the substrate, and reference numeral 78 denotes four tape protrusion prevention ribs arranged at left-right symmetrical positions corresponding to the peripheral side wall on the front side. Each side wall 76, prevention rib 78, etc. has the same height.
The position is different from the mold parting line _P2 . In the case described above, the relationship between the peripheral side wall, tape protrusion prevention rib, etc. and the parting line of the mold is the same. 82 is a trapezoidal recess having a head insertion portion 84 located at the center of the front side of the board;
Reference numeral 6 denotes a symmetrical elongated partition wall perpendicular to the substrate that partitions this head insertion section 84 from other tape storage sections within the lower case. 88 is this elongated partition wall 8
There are four double-shaped tape guide walls connected to the front side of the board 6 and arranged at symmetrical positions perpendicular to the substrate. These tape guide walls 88 are located slightly inward from the peripheral side wall 76 and the tape protrusion prevention rib 78, and are about twice as high as the surrounding side wall 76 and the tape protrusion prevention rib 78. The shape and structure of such a lower case are integrally manufactured by injection molding of plastic.

FIG. 5 is a schematic diagram showing the process of forming the lower case in this embodiment. In the figure, 90 is a space corresponding to the molded product formed between the fixed mold 92 and the movable mold 94, 96 is the color set there,
It is a film made of polyethylene terephthalate (PET) or other material that has pictures, text, etc. printed on it. In addition, 98 is a tape protrusion prevention rib 78,1
00 are spaces corresponding to the surrounding side walls 76, respectively. Therefore, when molten resin is injected from the molding machine into the space 90 through the gate near the parting line _P2 of the mold, the printing on the film 96 is caused to spread onto the case surface due to the pressure and temperature of the resin. It is transferred and the lower case is formed at the same time. In this way, the joint of the combined case, that is, the joint of the upper case, the peripheral side wall 76 of the lower case, the top of the tape protrusion prevention rib 78, etc., and the joint of the fixed side and the movable side of the mold are made different. Since the parting line P ₂ of the mold is closer to the printing transfer surface, the distance l ₂ from the parting line P ₂ to the printing transfer surface can be reduced. Then, naturally, the distance between the gate near the parting line _P2 and the printing transfer surface becomes smaller. In addition, when using transparent resin for the lower case, if the thickness of the case substrate and the position of parting line P ₂ match,
Since that line P ₂ becomes less noticeable, set l ₂ to 1.8~
It is preferable to set it to about 2.0 mm. When the distance between the two is reduced in this way, the time for the molten resin introduced from the gate to cover the entire surface of the film 96 is shortened accordingly, so that the film 96 will not be wrinkled or twisted. As a result, there will be no distortion or cutting in the print, and the finish will be good. Furthermore, by changing the printed content of the film using a monochromatic molding machine and an ordinary mold, cases with various designs can be easily produced, resulting in lower costs.

Effects of the invention According to the invention described above, even when film transfer molding is used, there is no distortion or cutting in printing, and a good finish can be achieved. Furthermore, it is inexpensive and has a greater degree of freedom in design.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an example of the lower case of a wide window type audio/magnetic tape cassette according to an embodiment of the present invention. FIG. 2 is a perspective view showing an example of a similar small window type lower case made by conventional monochromatic molding. FIG. 3 is a perspective view showing an example of a similar lower case of a wide window type using conventional two-color molding. FIG. 4 is a schematic view showing the process of forming the lower case by combining conventional monochromatic molding and film transfer molding. FIG. 5 is a schematic diagram showing the process of forming the lower case shown in FIG. 1. 70...Transparent window portion, 72...Hub shaft insertion hole, 7
4... Printing part, 76... Surrounding side wall, 78... Tape protrusion prevention rib, 82... Trapezoidal recess, 84...
... Head insertion part, 86 ... Partition bulkhead, 88 ...
Tape guide wall, 90... Space corresponding to the molded product, 92, 94... Fixed side of mold, movable side 96...
...Film, 98,100...Tape protrusion prevention rib, space corresponding to surrounding side wall, _P2 ...Parting line.

Claims (1)

[Scope of utility model registration request] 1. A magnetic tape cassette comprising a magnetic tape housed in a combined case formed by film transfer molding, characterized in that the seam of the case is different from the seam of a fixed side and a movable side of a mold.