Moon Phase Indicator Gear Ratio Optimization
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Solution Overview
Problem
Existing moon phase indicators in timepieces lack precision due to a direct drive mechanism that results in a 44-minute and 2.806-second error over two lunar months, and previous solutions with improved precision often complicate the mechanism with numerous gear wheels.
Innovation Solution
A timepiece design where the control wheel meshes with a transmission integral in rotation with a drive wheel, completing one revolution in a lunar month, allowing each step of the toothed disc to correspond to a precise fraction of a lunar month, with a gear ratio optimizing precision and using crystalline or electroformed materials for precise gear production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a toothed disc is driven directly by a control wheel completing one revolution in twenty-four hours, then the mechanism remains simple, but the moon phase display precision deteriorates with an error of 44 minutes and 2.806 seconds over two lunar months
Solution Approach 1:
The patent introduces an intermediary transmission mechanism between the control wheel and the toothed disc. The control wheel meshes with a transmission that is integral in rotation with a drive wheel, which in turn drives the toothed disc. This intermediary transmission allows the control wheel to complete one revolution in one Nth of a lunar month rather than directly driving the disc, thereby achieving precise moon phase indication without excessive mechanism complexity.
2Measurement precision
If previous solutions use a large number of gear wheels to improve precision, then the moon phase display precision improves, but the device complexity and size increase
Solution Approach 1:
The patent merges the functions of multiple separate gear wheels into a single integrated transmission mechanism. The transmission is integral in rotation with the drive wheel, combining what would traditionally require multiple discrete gears into one unified component. This merging achieves the necessary precision (control wheel completes one revolution in one Nth of a lunar month) while minimizing the number of parts and maintaining compact dimensions.
3Measurement precision
If the control wheel completes one revolution in one Nth of a lunar month with optimized gear ratio, then the moon phase display precision reaches optimal level accurate to the nearest tenth of a second, but the manufacturing complexity increases
Solution Approach 1:
The patent optimizes the gear ratio between the control wheel and transmission to achieve precise temporal correspondence. The gear ratio is set to 1.015895953757230, which corresponds to the ratio of a lunar month duration to one-thirtieth of that duration. This precise parameter adjustment allows the control wheel to complete exactly one revolution in one thirtieth of a lunar month (85048.07966 seconds), achieving optimal precision while maintaining manufacturability through careful parameter selection.
Data Source
Figure 1~3
Figure 2
AI summary
The timepiece has a control wheel (32) engaged with a setting wheel (38) which is connected in rotation with a driving wheel (40) executing a rotation in twenty-four hours. One lunar month corresponds to a number of steps of a toothed disk (22). The wheel (32) executes a rotation in 30th disk step of lunar month. Gear ratio between the wheels (32, 38) is equal to 1.015895953757230. The wheels (32, 38) has 692 and 703 teeth, respectively, and are made of crystalline material e.g. single-crystal silicon and polycrystalline silicon, and electroformed metal.