Horological Oscillator Frequency Setting by Femtosecond Laser Deformation
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Solution Overview
Problem
Existing methods for adjusting the frequency of mechanical horological oscillators, such as watch balances, require disassembly and reassembly, leading to inaccuracies and mechanical play, resulting in drifts of up to 10 seconds per day, which is undesirable for precision timekeeping.
Innovation Solution
A method using femtosecond laser excitation to induce permanent mechanical tension in a flexible mechanism embedded on the oscillator, allowing for fine adjustments of the oscillator's frequency without disassembly by modifying the inertia of the inertial mass through localized molecular expansion of the material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional mechanical adjustment methods are used to modify the frequency of the oscillator, then the frequency can be adjusted, but the watch must be disassembled and reassembled, causing mechanical play and drift of up to 10 seconds per day
Solution Approach 1:
The patent replaces traditional mechanical adjustment methods with optomechanical deformation using a laser beam. The laser induces localized thermal expansion in the balance wheel, deforming it to adjust the oscillation period without any mechanical contact or disassembly. This substitution eliminates mechanical play and hysteresis while achieving precise frequency control within 0-2 seconds per day accuracy range.
Solution Approach 2:
The patent changes the physical parameters of the balance wheel by inducing controlled thermal expansion through laser irradiation. The localized heating causes permanent deformation of the balance wheel's geometry, specifically altering its moment of inertia and stiffness characteristics. This parameter change enables fine frequency adjustment without mechanical intervention, maintaining timekeeping stability.
2Adaptability or versatility
If mechanical adjustment devices are installed in the oscillator, then frequency adjustment is possible, but the delicate mechanisms contribute to mechanical play causing drift after setting
Solution Approach 1:
The patent eliminates mechanical adjustment devices entirely by using optomechanical deformation. A laser beam remotely deforms the balance wheel through thermal expansion, replacing the need for mechanical pins, screws, or inertia blocks. This contactless approach removes all sources of mechanical play and hysteresis that would otherwise cause drift after setting, while maintaining full frequency adjustment capability.
Solution Approach 2:
The patent introduces light (laser beam) as an intermediary between the adjustment mechanism and the balance wheel. Instead of direct mechanical contact, the laser energy serves as the mediator that transfers energy to the balance wheel, inducing controlled thermal expansion and deformation. This intermediary approach enables precise adjustment without mechanical components that would create play or require disassembly.
3Ease of manufacture
If the watch is opened and the movement removed for frequency adjustment, then the frequency can be modified, but the result drifts by up to 10 seconds per day once the case is closed
Solution Approach 1:
The patent replaces mechanical disassembly with optical intervention. The laser beam can penetrate through the transparent case back or sapphire crystal to reach the balance wheel, enabling frequency adjustment without opening the watch. This substitution maintains manufacturing precision by avoiding the mechanical play and alignment issues that occur during disassembly and reassembly, achieving drift of only 0-2 seconds per day.
Solution Approach 2:
The patent performs frequency adjustment at any time during the watch's operation or storage, without requiring preliminary disassembly. The optomechanical method allows the watch to remain in its final assembled state throughout the adjustment process, eliminating the sequence of opening, adjusting, and closing operations that introduce errors. The frequency can be fine-tuned precisely while the watch remains closed and protected.
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 precise frequency adjustments within a range of 0-2 seconds per day, maintaining high positioning precision and zero hysteresis, thus improving the accuracy of mechanical timepieces.
Implementation Method 1
A method using femtosecond laser excitation to induce permanent mechanical tension in a flexible mechanism embedded on the oscillator, allowing for fine adjustments of the oscillator's frequency without disassembly by modifying the inertia of the inertial mass through localized molecular expansion of the material.
Data Source
AI summary
A method for the fine adjustment of the rate of a mechanical oscillator with an oscillating inertial mass, equipped, in a first step, with an actuator made of material suitable for irreversible local micro-expansion under the action of laser fires, to impart to an inertia-block a radial travel during suitable laser fires on a writing zone of the actuator, in a second step, the initial rate of the oscillator is set and measured, in a third step, the direction and the value of the deviation required to achieve a predetermined rate range, and of the travel to be imparted to inertia-blocks are calculated, in a fourth step, a writing zone is subjected to femtosecond laser fires to create expansion lines by local molecular expansion to radially deform the actuator, in a fifth step the rate is measured and the third step and fourth step are repeated if required.