JPS6342376Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a fixing structure for a back cover in a resin case for a watch.

Conventionally, as a structure for fixing the back cover of a watch case made of resin, a tap hole is provided in the watch case, and the back cover is fixed to the watch case by screwing the screw into the tap hole. It is being In this structure, a metal screw rotates to thread a tap hole in the watch case to form a screw hole, and the back cover is fixed by this screw fit.

However, in this case, since the fixing force between the resin watch case and the screw is weak, it is necessary to increase the diameter of the effective screw portion and also increase the screw depth. As a result, the watch case became larger, and once the screws were removed, the tap holes in the resin watch case were plastically deformed, making the screws less securely fixed.

The present invention solves the above-mentioned drawbacks by screwing together a metal screw with a hole provided in a bent part formed at the outer end of an inner frame of a reinforcing metal plate through a through hole in the back cover. The purpose of this structure is to increase the fixing force of the case back, reduce the dimensions of the screw part, and downsize the watch case.

Figure 1 is an exploded perspective view showing the conventional screw-fastening structure of the back cover, in which 1 is a resin watch case, 2
is the back cover, and 3 is a metal screw. An inner frame 4 formed of a metal plate is fixed to the resin watch case 1, and four tap holes 1a are provided on the lower surface of the resin watch case. The back cover 2 is fixed to the watch case 1 by screwing a metal screw 3 into the tap hole 1a through a through hole 2a.

FIG. 2 is a sectional view showing the periphery of the metal screw 3 of the conventional back cover fixing structure shown in FIG.
A reinforcing inner frame 4 is embedded in the inner peripheral portion 1b of the resin watch case 1 by insert molding when the resin case 1 is manufactured. As mentioned above, in this structure, in order to maintain the fixing force between the watch case 1 and the back cover 2, the engagement area between the screw 3 and the tap hole 1a must be large, and the outside of the metal screw 3 must be made large. As the diameter becomes larger, the watch case 1 also becomes larger.

Embodiments of the present invention will be described below with reference to FIGS. 3 and 4. FIG. 3 is a perspective view showing the inner frame 7 of the metal plate used in the fixing structure of the back cover according to the present invention, in which a bent portion 7b projects from the outer end of the cylindrical portion 7a of the inner frame 7 at a right angle from the cylindrical portion 7a. There is a hole 7c in the bent portion 7b. Figure 4 shows the inner frame 7 shown in Figure 3.
1 is a cross-sectional view showing the peripheral portion of an embodiment of the present invention using a watch case 1, in which a bent portion 7b of an inner frame 7 is embedded in a resin watch case 1. The back cover 2 is fixed by screwing a screw 8 into a hole 7c of a bent portion 7b of an inner frame 7 made of a metal plate through a through hole 2a. Here, an O-ring 9 is compressed between the back cover 2 and the cylindrical part 7a of the inner frame 7 to maintain waterproofness. It is engaged with and fixed to a receiving part 1c protruding from the lower surface of the part 7b.
Therefore, when the back cover 2 is directly engaged with the bent portion 7b of the inner frame 7, the step provided on the cylindrical portion 7a of the inner frame 7 is not required, so that the processing load on the inner frame 7 is reduced.

As is clear from the above, the configuration of the present invention not only makes it possible to increase the fixing force of the back cover using small screws, but also makes it possible to downsize the watch case. Furthermore, by embedding the bent portion, the resin serves as a stopper for properly compressing the O-ring, making it easier to process the inner frame of the metal plate.

[Brief explanation of the drawing]

Fig. 1 is an exploded perspective view showing a conventional back cover fixing structure using screws, Fig. 2 is a sectional view showing the area around the screw of the back cover fixing structure in Fig. 1, and Fig. 3 is a structure according to the present invention. FIG. 4 is a perspective view showing the inner frame used in the back cover fixing structure, and FIG. 4 is a sectional view showing the area around the screw using the inner frame of FIG. 3. 1...Watch case, 1a...Tap hole, 1b...
...Inner peripheral part, 1c... Receiving part, 2... Back cover, 2a...
Through hole, 3, 8...Screw, 4, 7...Inner frame, 7a
... Cylindrical part, 7b... Bent part, 7c... Hole, 9...
...O-ring.

Claims (1)

[Scope of utility model registration request] A watch case made of resin, in which an inner frame of a metal plate is formed at least on the inner periphery with a bent part having a hole at the outer end, and is embedded in the resin, and a through hole corresponding to the hole is provided on the back side of the watch case. A fixing structure for a back cover, characterized in that a cover is provided, and the back cover and the hole are screwed together with a screw through the through hole.