Timepiece Correction Device with Differential Gear and Memory Cam
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Solution Overview
Problem
Existing timepieces with complex display systems, such as perpetual calendars, face challenges in synchronizing multiple information displays and correcting them without applying damaging torque to the movement, especially when corrections are made around midnight, leading to mal-adjustments and desynchronization.
Innovation Solution
A correction device featuring a differential gear with a memory cam and clutch system, where the memory cam is desmodromically linked with the second input, allowing for bidirectional corrections without exerting torque on the movement during normal operation and automatically restoring synchronization by canceling the angular deviation after correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If correction means are provided for each sub-display to allow independent correction, then ease of operation is improved, but device complexity increases and synchronization errors may occur
Solution Approach 1:
The patent combines multiple correction functions into a single correction stem that operates all sub-displays simultaneously through a differential gear mechanism. Instead of providing separate correction means for each sub-display (date, month, day, year), the invention merges them into one unified correction interface that advances all displays together, maintaining synchronization while simplifying the user operation.
Solution Approach 2:
The correction stem serves multiple functions: it can correct the date, month, day, and year displays simultaneously, and it can also serve as a winding stem for the mainspring. This multi-functionality reduces the number of separate components needed and simplifies the overall device structure while maintaining ease of operation.
2Device complexity
If correction is performed in a single direction only, then device complexity is reduced, but ease of operation deteriorates as corrections require passing through the entire cycle
Solution Approach 1:
The patent introduces a clutch mechanism that dynamically changes the operational state of the differential gear, allowing it to switch between locked and unlocked states. This enables bidirectional correction by permitting the correction stem to rotate in both directions when the clutch is engaged, while maintaining simple unidirectional operation when the clutch is disengaged, thus resolving the contradiction between operational flexibility and mechanical simplicity.
3Stability of the object's composition
If the setting stem is used to correct calendar data, then synchronization of all information is maintained, but correcting around midnight may exert damaging torque on the movement
Solution Approach 1:
The patent introduces a differential gear as an intermediary mechanism between the correction stem and the calendar display system. This differential gear absorbs and isolates the torque generated during correction operations, preventing damaging forces from being transmitted to the movement. The differential acts as a buffer that allows correction to occur without directly loading the movement, thus protecting it from damage while maintaining synchronization.
4Ease of operation
If multiple push-buttons are used for correcting different sub-displays, then ease of operation is improved for specific corrections, but synchronization between displays becomes difficult to maintain
Solution Approach 1:
The patent merges the correction functions of multiple sub-displays into a single differential gear-driven mechanism. When the correction stem is activated, it simultaneously advances all sub-displays (date, month, day, year) through the differential gear, ensuring they remain synchronized. This eliminates the synchronization problems that arise when using separate push-buttons for each sub-display, as all corrections are applied uniformly and simultaneously.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables bidirectional corrections of complex display systems without damaging the movement, ensuring accurate synchronization and proper operation of the display device, particularly at midnight, by using a differential gear with a memory cam and clutch system.
Implementation Method 1
a differential gear having a first input, a second input and an output... the angular position of the output is defined as a function of the angular position of said first input and of that of said second input
Implementation Method 2
This memory cam is subjected to a return force supplied by an elastic member, such as a spring, tending to keep the memory cam in at least one predetermined angular position when the kinematic link between the control member and the second input is broken
Data Source
AI summary
A correction device for a timepiece, including a differential gear having a first input, a second input and an outlet output, wherein: — the first inlct input is arranged to be driven by a timepiece movement; — the second input is kinematically linked with a corrector gear extending from a control member and including a clutch for establishing and interrupting the kinematic link between the control member and the second input; — the output is arranged to drive a display device of the timepiece movement, the angular position of the output being defined on the basis of the angular position of the first input as well as on that of the second input, wherein the correction device further includes a memory cam desmodromically linked with the second input, in that the memory cam experiences a return force provided by a resilient member tending to maintain the memory cam in at least one predetermined angular position when the kinematic link between the control member and the second input is interrupted, the resilient member also being arranged to allow a rotation of the second input under the control of the control member when the kinematic link is established during the use of the correction device, and in that the correction device is arranged so that the incidence of the rotation of the second input during a correction on the angular position of the output is removed when the memory cam is located in the at least one predetermined angular position.