Clockwork Display Device Differential Gear Correction
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Solution Overview
Problem
Existing display devices for clock movements face challenges in correcting time-related indications without causing phase shifts or applying undesirable torque to the going train, which can affect the movement's rate and lead to incorrect indexing between hour and minute hands.
Innovation Solution
A display device with a first and second corrector gear system, allowing for continuous, step-by-step, or exclusive correction of time indications, using differential or serrated wheel mechanisms to maintain indexing and minimize torque impact on the going train.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a correction star with jumper is used to modify hour indication, then the hour indicator can be corrected without de-indexing with respect to minutes, but an undesirable torque is applied to the going train affecting the movement rate
Solution Approach 1:
A differential gear is introduced as an intermediary mechanism between the correction star and the hour indicator. The differential gear receives motion from both the correction star (for hour adjustment) and the minute wheel (via pinion), combining these inputs to drive the hour hand. This mediator allows independent correction of hours while maintaining proper synchronization with minutes, eliminating the torque transmission problem of direct connection.
Solution Approach 2:
The correction mechanism is modified by changing the transmission path from direct mechanical coupling to a differential gear system. This parameter change in the transmission mechanism allows the correction torque to be applied only to the differential input rather than directly to the going train, thus preserving movement rate stability while maintaining indexing precision.
2Reliability
If a differential gear with city disk is used for time zone correction, then torque impact on going train is reduced, but correct indexing between minute hand and time zone hour hand is not ensured
Solution Approach 1:
The differential gear is designed with multi-functionality: it serves both as a torque-isolating mechanism (protecting the going train) and as an indexing synchronization device. By connecting one input to the minute wheel via pinion and the other to the correction star, and the output to both the time zone hour hand and the central hour hand, it ensures proper indexing while reducing torque impact.
Solution Approach 2:
The correction mechanism is segmented into distinct functional components: the correction star for input, the differential gear for processing, and multiple output paths (one to time zone hour hand, another to central hour hand). This segmentation allows independent control of correction function while maintaining synchronization through the differential's inherent gear relationships.
3Ease of operation
If a braking system is used to prevent driving of second display member, then individual correction is enabled, but the system complexity increases
Solution Approach 1:
A braking system is introduced as an intermediary control mechanism between the correction star and the differential gear input. This brake can selectively engage to prevent motion transmission from the correction star to the differential, enabling individual correction of the first display member without affecting the second. While this adds a component, it provides precise control capability.
Data Source
Figure 1
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AI summary
Display device (9) for clockwork movement (1), said display device (9) comprising: - a first gear (11) intended to be driven by a driving element (3) comprising said movement (1); - a main correction device (15) arranged to selectively drive said first gear (11); - a first corrector gear (19) comprising a first input (19a; 27; 43) arranged to be driven by said first gear (11), a second input (19b; 29; 45) intended to be driven manually in steps, and an output (19c; 25, 33; 25, 51), arranged to drive a first display element (23) of a first time-related indication.- a second correcting gear (57) comprising a first input (57a) arranged to be driven by said output (19c; 25, 33; 25; 51) of said first correcting gear (19), a second input (57b) intended to be driven manually in steps, and an output (57c) arranged to drive a second display element (61) of a second time-related indication.