JPH0345347Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to the structure of a window for viewing the winding amount of a tape in a cassette in which a magnetic tape is wound between two hubs.

[Prior Art] Since a cassette tape is molded from a synthetic resin that is inherently opaque, the amount of tape winding on the two internal hubs cannot be seen from the outside. Therefore, a transparent window is provided in the center of each cassette half to allow viewing of the tape windings. This window is made by fitting a rectangular plate of transparent polystyrene resin, separate from the resin of the cassette case body, into a window hole provided in the case and thermally welding it. Normally, this hole has a step 12 structure in which the peripheral edge of the hole 11 is lowered one step as shown in FIG. 3. A transparent plate 13 is fitted into the hole 11 and supported by the step 12. The periphery of the transparent plate 13 is bonded to the stepped portion 12 by ultrasonic fusion. At this time, the respective resins of the transparent plate 13 and the stepped portion 12 of the case are melted and fused together, but a portion of the molten resin 14 protrudes from the overlapping portion to the outside and peeks into the window 13, resulting in an unsightly appearance. .

[Problems to be Solved by the Invention] Therefore, the inventor of the present invention has devised a method for effectively disposing of the molten resin that protrudes when the transparent plate is fused to the window hole.

[Means for solving the problem] In the present invention, a lower notch step is formed at the edge of the step portion on which the transparent plate is placed, and a place is provided in which the molten resin protruding from this step is accommodated.

[Embodiment] FIG. 1 shows a cross section of a window portion of a cassette case, in which a fitting step 2 is formed around a window hole 1 of the cassette case, which is one step lower than the inner surface 5 of the case half. Further, at the edge of this step 2, a cutout step 3 is provided which is further lowered.

Since the present invention is constructed in this way, the transparent plate 4 (indicated by a dotted line) is placed on the step 2,
The contact surface portion with this stage is ultrasonically fused. At this time, transparent plate 4 or stage 2 of the cassette case half
Even if the resin melts, the molten resin is contained in the notch step 3 provided at the tip of the step, which is lower than the other step, so that it will not protrude further and peek into the window part.

[Effects of the invention] In this way, the cassette can be manufactured simply by adding a notch step to the conventional cassette structure, so it can be easily integrally molded, and the appearance is good because the molten resin does not peek into the window part.

Although the structure of the present invention is a notched step, the same effect can be obtained by forming a large number of grooves on the step surface and storing the molten resin in the grooves.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a window portion showing an embodiment of the present invention. FIG. 2 is a perspective view of the cassette case half. FIG. 3 is a partial sectional view of a conventional window. 1...Wind hole, 2...Step, 3...Notch step,
4...Transparent plate.

Claims (1)

[Scope of utility model registration request] A cassette case having a step lower than the inner surface of the case around the window hole of the cassette case, and a cutout step lower than the step further provided at the edge of this step.