Watch Movement Motor Control for Chrono Date Accuracy
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Solution Overview
Problem
Existing watch movement technologies, such as those described in US 6,185,158, are limited in their ability to accurately display time intervals beyond a single revolution of the chrono hand, as they rely on a single electromechanical motor to drive both the chrono hand and date display, leading to inaccuracies when trying to display hours or additional time units, as the motor's periodic actuation mechanism is not designed to handle multiple date changes during the timed interval.
Innovation Solution
The method involves periodically reversing the rotation of the chrono hand indicator during active mode, allowing it to make successive backward steps, while keeping the date indicator stationary, using a multifunctional motor to drive both indicators, ensuring continuous display accuracy across varying time intervals by alternating between forward and reverse rotations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single electromechanical motor drives both the chrono hand and date display using a Geneva mechanism, then the device complexity is reduced, but the measurement precision of time intervals beyond a single revolution deteriorates
Solution Approach 1:
The patent divides the drive system into two independent electromechanical motors: a first motor dedicated to driving the chrono hand for time interval measurement, and a second motor dedicated to driving the date display. This segmentation allows each motor to perform its specific function independently, eliminating the interference and precision loss that occurs when a single motor attempts to drive both mechanisms through a Geneva mechanism.
Solution Approach 2:
Each motor is designed with multi-functionality to reduce overall device complexity. The first motor can drive both the chrono hand and optionally the seconds hand, while the second motor can drive both the date window and optionally the day window. This universal design allows one motor to handle multiple related functions without requiring separate dedicated motors for each indicator.
2Duration of action of moving object
If the periodic actuation mobile completes multiple laps during the timed interval, then the chrono hand can display extended time intervals, but the date display accuracy deteriorates due to unintended date changes
Solution Approach 1:
By separating the drive mechanisms for the chrono hand and date display into two independent motors, the patent eliminates the coupling that caused date display errors. The first motor can freely rotate the chrono hand through multiple revolutions to measure extended time intervals, while the second motor independently controls the date display based on its own actuation cycle, preventing unintended date changes during chrono measurement.
Solution Approach 2:
The patent introduces an intermediary control mechanism where the first motor's rotation is selectively transmitted to the chrono hand through a transmission mechanism that can accommodate multiple revolutions, while the second motor separately controls the date display. This intermediary arrangement allows the chrono hand to complete multiple laps without directly affecting the date display mechanism, thus maintaining date display accuracy during extended time measurements.
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
This approach enables accurate display of time parameters, including hours and date units, by maintaining the date indicator in a stable position, allowing the chrono hand to complete multiple revolutions without affecting the date display, thus overcoming the limitations of previous technologies.
Implementation Method 1
electronic watch movements comprising an analog display driven by one or more electromechanical motors
Data Source
Figure 1~3
Figure 2
AI summary
In the control method for an analog display device fitted to a timepiece movement, the motor is used both for driving a first indicator of a time parameter and a second periodically driven indicator. To this end, the motor is controlled such that, when the first indicator is in an operating mode and the second indicator is arranged to remain substantially immobile, said first indicator is driven in rotation by the motor alternately. The first indicator is driven in a forward direction, to display the time parameter, during a first period in which a periodic actuation wheel set is simultaneously driven in positions of its area of non-actuation, and in a backward direction, in accelerated mode, during a second period following the first period, before the periodic actuation wheel set is driven in a position of its area of actuation.