1. Field of the Invention
The present invention relates to a timepiece and a battery lid structure for a timepiece case.
2. Related Art
Conventionally, there have been those using bayonet mechanisms as a method for fitting a timepiece-case battery lid to a timepiece-case back lid having a back lid or a bottom-surface battery hole of an integral-type timepiece case.
The forgoing method for fitting a battery lid using a bayonet mechanism involves the following problems.
(1) Manufacture cost is high because of the necessity of complicate machining, such as for slant surfaces or stoppers, on an inner bottom surface of a back lid or case on a side to which the battery lid is to be fitted.
(2) In order to fit with and positively hold a battery lid, the bottom surface of the back lid or case requires a thickness greater than a predetermined thickness resulting in increase of timepiece overall thickness.
It is an object of the present invention to provide a battery lid structure for a timepiece case which solves the problems possessed by the related art and can reduce the thickness of the bottom surface of the back lid or case without the necessity of complicate machining, such as for slant surfaces or stops, in a bottom inner surface of the back lid or case with a result that the timepiece overall can be reduced in thickness.
A first form of the present invention solved the above problem is a battery lid structure comprising: a case battery hole circumferentially having a plurality of alternate larger-diameter arcs and smaller-diameter arcs in a bottom surface of a back lid of a timepiece case having a back lid or an integral-type timepiece case; arcuate penthouses provided in number corresponding to the large-diameter arcs in the battery lid at a timepiece-interior side and having a radius smaller than a radius of the larger-diameter arcs to have a wall portion at an end thereof; a different-shaped barrel portion continuing from a timepiece-exterior side of the arcuate penthouse and having a radius smaller than a radius of the small-diameter arc; a straight barrel portion continuing from a timepiece-exterior side of the different-shaped barrel portion and having a radius greater than a radius of the arcuate penthouse; a large-diameter flange portion continuing from an timepiece-exterior side of the straight barrel portion and having a radius greater than a radius of the large-diameter arc to provide a rectangular groove in an outer surface thereof; and a sealing elastic O-ring clamped between a surface of the large-diameter flange portion at the timepiece-interior side and a surface of the back lid or the case bottom surface at the timepiece-exterior side; wherein a circumferential tip of the arcuate penthouse at a wall-opposed side is formed as a tapered portion; the arcuate penthouse in part of a surface at the timepiece-exterior side having an arcuate protrusion; and the battery lid being fitted between the surface of the arcuate penthouse of the battery lid at the timepiece-exterior side and the surface of the straight barrel portion at a timepiece-interior side, in a manner clamping the small-diameter arc portion of the battery hole.
A second form of the invention solved the above problem is a battery lid structure for a timepiece case that, in the first form, a rib is provided which horizontally protrudes from an entire periphery of an inner surface of the sealing elastic O-ring.
The structure as in the first form provides the following effect.
That is, the battery lid is assembled matched to the form of the different-shaped battery hole provided in the timepiece-case back lid or case bottom surface, and a coin or the like is inserted in the rectangular groove in the outer surface of the battery lid and the battery lid is rotated. Thereupon, the small-diameter arc portion around the battery hole in the back lid or case bottom surface enters from the tapered portion at the circumferential tip of the arcuate penthouse at a wall-opposed side to between a timepiece-exterior side surface of the arcuate penthouse and the timepiece inner side surface of the straight barrel portion. The abutment of the tip of the smaller-diameter arc portion against an end wall of the smaller-diameter arcuate. penthouse regulates the battery lid from rotating furthermore. Also, the battery lid is prevented from vertically chattering by an elastic force of the O-ring clamped between a timepiece-exterior-side surface of the back lid or case bottom surface and the timepiece-interior-side surface of the larger diameter flange portion of the battery lid. Furthermore, interference occurs between an arcuate protrusion provided in part of the timepiece-exterior-side surface of the arcuate penthouse and the smaller-diameter arcuate portion around the battery hole in the back lid or case bottom surface. Heavy tightening is made upon rotating the battery lid thus preventing against disengagement due to natural reverse rotation.
When removing the battery lid, a coin or the like is inserted in the rectangular groove in the outer surface of the battery lid to rotate the battery lid in a direction reverse to the forgoing case. As a result, the arcuate penthouse of the back lid comes to a position corresponding to the larger-diameter arc portion of the battery hole in the back lid or case bottom surface. The smaller-diameter arc portion is released from clamping by the timepiece-exterior-side surface of the arcuate penthouse of the battery lid and the timepiece-interior-side surface of the straight barrel portion, enabling the battery lid to be removed.
The structure as in the second form provides the following operation, besides the operation of the first embodiment.
That is, the rib protruding horizontally from the entire periphery of the inner surface of the sealing elastic O-ring is clamped between the arcuate penthouse and the straight barrel portion of the battery lid. Accordingly, when the battery lid is removed from the battery hole of the timepiece case, the sealing elastic O-ring will not be disengaged from the battery lid. As a result, there is no possibility that the sealing elastic O-ring be fallen out and lost.