Equation of Time Lever Mechanism for Watch Movement
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Solution Overview
Problem
Existing timepiece mechanisms for indicating the difference between civil time and true solar time are complex, prone to adjustment difficulties, and can be disrupted by shocks due to the need for a second mechanism to correct the solar time minute hand, which complicates construction and introduces friction-related issues.
Innovation Solution
A running equation of time device that uses a kinematically connected frame and equation of time lever to represent the difference between civil and solar time, with a barrel and core system that adjusts the solar time minute hand clockwise and counterclockwise using a single mechanism, ensuring precise alignment with the civil time minute hand.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a second mechanism is provided to move the solar time minute hand back counterclockwise, then the position of the solar time minute hand can be corrected in both directions, but the device complexity increases considerably
Solution Approach 1:
The patent merges the clockwise and counterclockwise correction functions into a single mechanism. The equation of time lever, when pressed, can move the barrel pinion first in the clockwise direction and then in the counterclockwise direction, eliminating the need for separate mechanisms for each direction of correction.
Solution Approach 2:
The equation of time lever serves multiple functions: it acts as both the driving element for clockwise correction and the controlling element for counterclockwise correction when pressed. This multi-functional design simplifies the overall mechanism while maintaining full correction capability in both directions.
2Ease of operation
If the barrel of the solar time minute hand can rotate freely relative to the civil time minute hand, then adjustment is easier, but the mechanism becomes prone to shock-induced errors and friction-related issues
Solution Approach 1:
The patent implements a dynamic locking system where the barrel can rotate freely during normal operation for easy adjustment, but can be locked in position when needed. The blocking means engage with the barrel to prevent rotation and maintain the corrected position, providing both ease of adjustment and shock resistance.
3Reliability
If the force of the small spring is made strong enough to turn the friction barrel, then the barrel can be reliably moved, but it cannot remain sufficient to make it turn when disengaged
Solution Approach 1:
The patent uses periodic action where the small spring provides strong force only when needed (when the barrel is disengaged and needs to be moved), and the blocking means prevent the spring from continuously exerting force. This allows the spring to be strong enough for reliable movement without causing continuous friction or wear.
Data Source
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AI summary
The watch movement includes a running equation of time device comprising a cannon (113) intended to carry a solar time minute hand mounted concentrically with the civil time minute and hour hands, an equation of time cam (101) driven in rotation by the movement at a rate of one revolution per year, and a correction mechanism intended to periodically adjust the angular offset of the solar time minute hand relative to the civil time minute hand, according to the angular position of the equation of time cam.