Reduction gear of electronic wristwatch with stepping motor and sweep second hand
First Claim
1. A reduction gear of an electronic wristwatch having a stepping motor and a sweep second, comprising three concentric output shafts rotating at different speeds, a first one of the shafts being provided with a bearing in the form of a supporting bush press-fitted in a bore in a wristwatch plate, said first shaft making one revolution per hour and supporting a friction wheel, the shafts being drivingly connected to one another and to a shaft of the stepping motor through gear wheels and a bridge coordinated with respect to the plate and secured thereon by threaded means, wherein the improvement comprises the first shaft freely passing through a bore provided in the supporting bush, the supporting bush being press-fitted in the bore of the plate so that a portion of said supporting bush projects from the plate towards the bridge, said shaft being prevented from unlimited axial displacement in one direction by the end face of the supporting bush and in the other direction by the end face of a gear wheel which is mounted on said first shaft with an interference fit.
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Accused Products
Abstract
The reduction gear of an electronic wristwatch comprises three concentric output shafts adapted to be rotated at different speeds and operatively connected with each other and with the shaft of a stepping motor through gear wheels. A shaft making one revolution per hour has mounted thereon a friction wheel and a bearing means made in the form of a supporting bush press fitted in a bore of the plate of the wristwatch. The bush is mounted so that a portion thereof projects from the plate toward the bridge of the wristwatch, coordinated with respect to the plate and attached thereto by threaded means. The shaft passes freely through a bore in the supporting bush and is restricted from an unlimited axial displacement in one direction by an end face of the supporting bush, and in the other direction by the end face of that pinion which is mounted on the shaft with interference fit. The reduction gear of an electronic wristwatch can be used by the watch-making industry in the production of quartz wristwatches having a stepping motor, and of like timepieces.
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Citations
9 Claims
- 1. A reduction gear of an electronic wristwatch having a stepping motor and a sweep second, comprising three concentric output shafts rotating at different speeds, a first one of the shafts being provided with a bearing in the form of a supporting bush press-fitted in a bore in a wristwatch plate, said first shaft making one revolution per hour and supporting a friction wheel, the shafts being drivingly connected to one another and to a shaft of the stepping motor through gear wheels and a bridge coordinated with respect to the plate and secured thereon by threaded means, wherein the improvement comprises the first shaft freely passing through a bore provided in the supporting bush, the supporting bush being press-fitted in the bore of the plate so that a portion of said supporting bush projects from the plate towards the bridge, said shaft being prevented from unlimited axial displacement in one direction by the end face of the supporting bush and in the other direction by the end face of a gear wheel which is mounted on said first shaft with an interference fit.
Specification