JPH0814954B2 - Tape car ledge - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tape cartridge having a transparent window for visually observing the winding state of a tape, and more specifically, a two-color molding method using a transparent window plate in a main body case. The present invention relates to an integrally molded product.

[Conventional technology]

A conventional tape cartridge having a transparent window of this type is shown in FIG. Here, an audio tape cartridge of a digital recording / reproducing system is shown as an example. In order to simplify the assembly of the transparent window plate 2, the window plate 2 is integrally molded in the main body case 1 by a two-color molding method. Become. At this time, in order to improve the internal visibility for visually observing the winding state of the tape, the window plate 2 is made thin to increase the transparency, or when the window is widened, the window plate 2 receives an external load. Since it is easily deformed or broken when received, it is conceivable to provide the rib 3 from the main body case 1 across the window plate 2 to reinforce it. Also, the rib 3
Is also valuable in terms of changing or changing the design of wide windows.

However, when the main body case 1 and the rib 3 are actually primary-molded by the two-color molding method and the window plate 2 is secondary-molded, it is difficult to obtain the rib 3 having an ideal shape. That is, as shown in FIG. 6, when the main body case 1 and the ribs 3 are primary molded and then the window plate 2 is molded, the ribs 3 lose the excessive resin pressure (resin flow M) on the secondary molding side. In Fig. 5, inconvenient deformation occurred as shown by the phantom line F, which was not preferable in terms of window reinforcement and appearance. In particular, the deformation of the ribs 3 due to the resin pressure is formed as narrow as possible so that the ribs 3 do not hinder the visibility of the inside, or appear significantly near the gate G.

[Problems to be solved by the invention]

The present invention solves the problem of rib deformation during molding of the transparent window plate, secures a window reinforcing function by the rib, enables narrowing of the rib to improve internal visibility, and improves the appearance of the window design. An object of the present invention is to provide a tape cartridge that can be designed.

[Means for solving problems]

The present invention is based on the premise that the main body case 1 and the ribs 3 are primary-molded by the two-color molding method, and the transparent window plate 2 is secondary-molded, and as shown in FIG. The outer surface 2a of the plate 2 is shaped to be convex. Then, as shown in FIG. 2 (b), the rib 3 is formed by the primary molding so as to be inserted into the concave portion 10 of the upper mold 5 on the fixed side. It is possible to counter this without being deformed by the resin pressure at the time of the secondary molding.

〔The invention's effect〕

According to the present invention, the rib 3 that is primarily formed together with the main body case 1 is formed so as to be more convex than the outer surface 2a of the transparent window plate 2 that is secondarily formed. Two
At the time of the next molding, the rib 3 can be surely prevented from being deformed by the resin pressure, the window reinforcing function is secured, and the width is narrow enough not to hinder the internal visibility, and the rib has a desired shape without impairing the appearance. There is an advantage that the rib 3 can be easily obtained.

〔Example〕

First Embodiment of a tape cartridge according to the present invention
It will be described with reference to FIG. 2 and FIG.

FIG. 1 shows the cross-sectional shapes of a body case and a transparent window plate that are integrally molded by the two-color molding method. The rib 3 that is primarily molded together with the body case 1 is outside the window plate 2 that is secondarily molded. It is formed so as to be convex from the surface 2a. Reference numeral 4 denotes a scale display protrusion for visualizing the tape winding amount, which is provided on the outer surface 2a side of the window plate 2.

The rib 3 is formed so as to traverse the window plate 2 from the main body case 1 when seen in a plan view, similar to that shown in FIG.

FIG. 2 (a) shows a mold structure for the primary molding of the main body case 1 and the ribs 3 by the two-color molding method of the core back system.
FIG. 1B is a cross-sectional view showing a mold structure for secondary molding of the window plate 2. In the primary molding state shown in FIG. 2 (a), a cavity 8 is formed between the upper die 5 on the fixed side, the lower die 6 on the movable side, and the core block 7, and by filling this with resin, The main body case 1 and the ribs 3 are molded (see FIG. 2 (b)).

In the secondary molding state shown in FIG. 2B, the core block 7 is retracted by a predetermined stroke to form a cavity 9 in which the molding resin of the window plate 2 is filled from the gate G.
The gate G is set at the center position of the window plate 2 as shown in FIG.

The upper mold 5 has a concave portion 10 for molding the convex portion 3a of the rib 3 protruding by a from the outer surface 2a of the window plate 2. The concave portion 10 has a cross-sectional shape as shown in FIG. The protrusion 3a of the rib 3 is formed to have a rectangular cross section. If the convex portion 3a of the rib 3 is formed in a square shape in this way, even if the convex portion 3a is inserted into the upper mold 5 as shallowly as possible so that the upper mold 5 can be easily removed from the mold after the secondary molding. This is advantageous because the rib 3 does not sometimes come out of the recess 10 due to the resin pressure.

On the other hand, the core block 7 has a concave portion 11 for molding a portion 3b of the rib 3 which sinks into the window plate 2. The concave portion 11 has a cross-sectional shape as shown in FIG. The part 3b which sinks inside is formed in a trapezoidal cross section having taper 12 on both sides, and is formed so as to reduce the resistance against the secondary molding resin pressure and prevent the disturbance of the resin flow as much as possible.
The angle b of the taper 12 is set to 45 degrees or less, more preferably 30 degrees. This is because when the temperature is 45 degrees or higher, the resin pressure reduction and turbulent flow prevention effects cannot be expected so much.

[Another embodiment]

FIG. 3 shows a modified example of the cross-sectional shape of the rib 3. Instead of attaching the taper 12 to the portion 3b of the rib 3 that sinks in the window plate 2, the radius 13 is attached. It is possible to effectively prevent the reduction of the resin pressure on the secondary molding side and the disturbance of the resin flow.

FIGS. 4 (a) and 4 (b) show still another modified embodiment of the rib 3, in which the rib 3 which is primarily formed together with the main body case 1 via the connecting portion 3d is secondarily formed. 2 is set in the approximate center position, and the window plate 2 is provided on the outer surface side of the rib 3.
2 has a convex portion 3a which is convex from the outer surface and a concave portion 3c which is flush with the outer surface of the window plate 2.

It is needless to say that the present invention is not limited to an audio tape cartridge of a digital recording / reproducing system, and can be similarly applied to other various tape cartridges for audio or video.

[Brief description of drawings]

1 and 2 show an embodiment of the tape cartridge according to the present invention. FIG. 1 is a sectional view of a main part, and FIGS. 2 (a) and 2 (b) are two colors of a main body case and a window plate. 2A and 2B are cross-sectional views of a molding die structure, FIG. 2A is a primary molding state diagram, and FIG. 2B is a secondary molding state diagram. FIG. 3 is a cross-sectional view of essential parts showing another embodiment of the present invention. FIGS. 4 (a) and 4 (b) show another embodiment of the present invention. FIG. 4 (a) is an external plan view of the entire tape cartridge, and FIG. 4 (b) is FIG. 4 (a). It is an AA line expanded sectional view in. FIG. 5 is a plan view illustrating a tape cartridge as an object of the present invention. FIG. 6 is a cross-sectional view of essential parts showing a comparative example with the present invention. 1 ... Main body case, 2 ... Window plate, 3 ... Rib, 3a ... Rib projection.

Claims (1)

[Claims] 1. A tape cartridge comprising a main body case 1 primary-molded by a two-color molding method and a transparent window plate 2 integrally molded by secondary molding. A tape cartridge, characterized in that it is integrally formed on the window plate 2 so as to be convex from the outer surface 2a thereof.