Local and GMT Timepiece Displays with Differential Star-Jumper Coupling
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Solution Overview
Problem
Existing timepieces with differential gears for correcting local and GMT times suffer from play and desynchronization issues, particularly during bidirectional corrections, leading to incorrect repositioning of GMT time displays relative to local time displays.
Innovation Solution
A timepiece design incorporating a parallel-mounted gear train connected to the differential gear output via a star/jumper system, allowing disengageable coupling for simultaneous or independent corrections of local and GMT times, ensuring synchronized repositioning of GMT time displays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a differential gear is used to enable independent correction of GMT time, then the GMT time can be corrected independently of local time, but play is introduced in the GMT time display and correction gear trains causing desynchronization
Solution Approach 1:
A locking mechanism acts as an intermediary between the differential gear and the GMT time display wheel. This locking mechanism engages with a cam profile on the GMT time display wheel to prevent backward movement, thereby eliminating play while preserving the differential gear's ability to enable independent correction of GMT time.
Solution Approach 2:
The locking mechanism applies a preliminary counteracting force against the harmful backward movement of the GMT time display wheel. By preemptively preventing the wheel from moving backward during correction operations, the system eliminates play before it can cause desynchronization between GMT and local time displays.
2Adaptability or versatility
If bidirectional correction is implemented, then both forward and backward time adjustment is possible, but play increases in the gear train leading to desynchronization
Solution Approach 1:
The locking mechanism serves as an intermediary that selectively restricts backward movement while permitting forward movement. The cam profile engagement allows the GMT time display wheel to move forward during correction but prevents it from moving backward, thereby eliminating play that would otherwise accumulate during bidirectional correction operations.
3Ease of operation
If the minute display member moves during HT time correction, then HT time can be corrected, but the GMT time display member may become desynchronized
Solution Approach 1:
The locking mechanism acts as an intermediary that decouples the GMT time display wheel from backward movement during HT time correction. When the locking mechanism is engaged, it prevents the GMT time display wheel from moving backward even if the minute display member moves, thereby maintaining synchronization while allowing HT time correction to proceed.
Data Source
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AI summary
The present invention relates to a timepiece (1) including a first display member (6) for displaying a local time LT, a second display member (8) for displaying a GMT time, a drive wheel (10) of the first display member (6), a first correction mechanism (23) arranged to be kinematically linked to the drive wheel (10) of the first display member (6) to allow simultaneous correction of the local time LT and the GMT time, a second correction mechanism (32) of the second display member (8), arranged to be able to correct the GMT time independently of the local time LT, a drive mechanism (34) of the second display member (8) including a differential gear (22) comprising a first input arranged to be kinematically linked to the drive wheel (10) of the first display member (6), a second input arranged to be kinematically linked to the second correction mechanism (32) of the second display member (8), and an output arranged to drive said second display member (8). The timepiece includes a geartrain (48) mounted in parallel with the drive mechanism (34) of the second display member (8) and arranged to be kinematically linked to the drive wheel (10) of the first display member (6) and to be kinematically linked to the output of the differential gear (22) in a disengageable manner by means of a first star (50) linked to said geartrain (48) mounted in parallel and a first jumper (52) connected to the output of the differential gear (22) and cooperating with said first star (50) such that said output is driven by said geartrain (48) mounted in parallel during a simultaneous correction of the local time LT and the GMT time by the first correction mechanism (23) and such that said output is uncoupled from said geartrain (48) mounted in parallel during a correction of the GMT time independently of the local time LT by the second correction mechanism (32) while allowing, after correction, a repositioning of the second display member (8) synchronised with the positioning of the first display member (6).