Date Display Mechanism With Segmented Wheels For Shock-Resistant Transitions
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Solution Overview
Problem
Existing date display mechanisms in timepieces, particularly wristwatches, face challenges in readability due to small indication sizes and complex mechanisms for managing date transitions and locking systems, especially when switching from 31 to 01, which can lead to de-indexing issues during impact or inertia.
Innovation Solution
A date display mechanism featuring separate mobiles for units and tens indicators with a unique tooth profile on the date wheel set, including toothless sectors to manage the transition from 31 to 01 without driving the units indicator, ensuring it remains stationary, and incorporating a flat to prevent de-indexing in case of shock or inertia.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate mobiles are used for units and tens indicators, then readability is improved, but device complexity increases due to additional locking systems and impact prevention mechanisms
Solution Approach 1:
The date display is segmented into two separate mobiles: one for units digit and one for tens digit. Each mobile is independently driven and locked, allowing them to be controlled separately. This segmentation enables the units mobile to remain stationary during 31→01 transition while the tens mobile advances, solving the readability issue while managing complexity through modular design.
Solution Approach 2:
A selective blocking mechanism acts as an intermediary between the date wheel and the units mobile. This blocking mechanism selectively prevents the units mobile from moving during specific transitions (31→01) while allowing normal operation otherwise. The blocking mechanism includes a blocking element that engages with a blocking sector on the units mobile, providing intelligent control without requiring complex locking systems on both mobiles.
2Productivity
If a tooth is removed from the date wheel for 31→01 transition, then the units indicator can remain stationary, but reliability decreases due to potential de-indexing during impact
Solution Approach 1:
A blocking mechanism serves as an intermediary between the date wheel and the units mobile during the 31→01 transition. The blocking mechanism includes a blocking element that selectively engages with a blocking sector on the units mobile, preventing it from moving during the transition while maintaining positive engagement during normal operation. This eliminates the need to remove teeth from the date wheel while preventing de-indexing through controlled blocking.
Solution Approach 2:
The blocking sector on the units mobile has a specific local geometry designed to engage with the blocking element only during the 31→01 transition. The blocking sector is positioned and shaped such that it provides selective blocking action precisely when needed, while maintaining normal meshing engagement at all other positions. This local differentiation of engagement quality ensures reliability without compromising transition simplicity.
3Reliability
If locking systems are added to prevent de-indexing, then reliability is improved, but device complexity increases
Solution Approach 1:
The blocking mechanism acts as an intermediary that provides selective blocking action without requiring complex locking systems on both mobiles. The blocking element and blocking sector create a simple, localized engagement that prevents de-indexing of the units mobile during impact while allowing normal operation. This intermediary approach provides reliability with minimal added complexity compared to comprehensive locking systems.
Solution Approach 2:
The blocking mechanism is self-actuating through the natural motion of the date wheel and mobiles. The blocking element automatically engages with the blocking sector when the units mobile attempts to move during the 31→01 transition, and disengages automatically when normal operation resumes. This self-service mechanism provides impact prevention without requiring external control systems or complex actuation mechanisms.
Data Source
Figure 1
Figure 2
Figure 3a~3b
AI summary
The present invention relates to a date display mechanism comprising a units indicator (12), a tens indicator (11) and a date wheel (5) connected to the units indicator (12) and the tens indicator (11) for their drive, the kinematic chain connecting the date wheel (5) to the units indicator (12) comprising a first wheel (52) and a second wheel (7), the first wheel (52) being arranged to mesh with the second wheel (7).The first mobile (52) comprises twenty-nine teeth (520, 523) cut on a profile of thirty-one teeth as well as a first and a second toothless sectors (521, 522) each occupying the place of one tooth, the first and second toothless sectors (521, 522) of the first mobile (52) being non-adjacent and separated by a tooth (523) and is arranged to make thirty-one steps when it makes one turn and to drive the second mobile (7) so that when the first mobile makes one turn, it drives said second mobile (7) by one turn as well, said second mobile (7) making only thirty steps and one stop.