Piezoelectric Balance Spring Electrode Layout for Frequency Control
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Solution Overview
Problem
Existing piezoelectric elements in automatic frequency control circuits for oscillating mechanical systems, such as those in mechanical watches, face challenges in precise control of oscillation frequency due to the complexity of design and the cancellation of electrical charges caused by the change in crystal orientation of piezoelectric materials.
Innovation Solution
A piezoelectric element with a balance spring made of piezoelectric crystal or ceramic, featuring electrodes placed in a predetermined angular distribution along the spring, which collects electrical charges effectively and avoids mutual cancellation, allowing for precise control of oscillation frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If piezoelectric films are deposited over the entire length of the balance spring, then the piezoelectric effect can be utilized, but the manufacturing complexity and cost increase
Solution Approach 1:
The balance spring is divided into multiple segments along its length, with piezoelectric films deposited only on specific segments rather than the entire length. This segmentation allows the piezoelectric effect to be utilized effectively while reducing manufacturing complexity and cost by limiting the deposition process to necessary areas only.
Solution Approach 2:
Different portions of the balance spring are treated differently: some segments receive piezoelectric film deposition while others remain untreated. This local quality approach ensures that the piezoelectric effect is applied where most needed for frequency control, avoiding unnecessary manufacturing steps on other portions.
2Reliability
If piezoelectric films are deposited over the entire length of the balance spring, then frequency control is achieved, but manufacturing cost increases
Solution Approach 1:
The balance spring is divided into multiple segments along its length, with piezoelectric films deposited only on specific segments rather than the entire length. This segmentation allows the piezoelectric effect to be utilized effectively while reducing manufacturing complexity and cost by limiting the deposition process to necessary areas only.
Solution Approach 2:
Instead of applying piezoelectric films to the entire balance spring (excessive action), films are applied only to specific segments where the effect is most needed for frequency control (partial action). This reduces material usage and manufacturing cost while maintaining sufficient control capability.
3Power
If electrodes are placed on piezoelectric material with changing crystal orientation, then electrical charges are generated, but mutual cancellation of charges occurs
Solution Approach 1:
The balance spring is divided into multiple segments along its length, with piezoelectric films deposited only on specific segments rather than the entire length. This segmentation allows the piezoelectric effect to be utilized effectively while reducing manufacturing complexity and cost by limiting the deposition process to necessary areas only.
Solution Approach 2:
Different portions of the balance spring are treated differently: some segments receive piezoelectric film deposition while others remain untreated. This local quality approach ensures that the piezoelectric effect is applied where most needed for frequency control, avoiding unnecessary manufacturing steps on other portions.
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
The solution enables simple and economical manufacturing of piezoelectric elements with enhanced performance, maximizing the collection of electrical charges and allowing for precise control of oscillation frequency, overcoming the limitations of previous designs.
Implementation Method 1
The piezoelectric element may include the balance spring, on which it is known to deposit films of a (PZT type) piezoelectric material, for example on the internal and external surfaces of the spring
Implementation Method 2
a frequency adaptation signal is generated which, once applied to the piezoelectric element, allows a compressive or extension force to be generated on the element in order to brake or accelerate the oscillation
Data Source
AI summary
A piezoelectric element for an automatic frequency control circuit. The element includes a balance spring formed of a piezoelectric crystal strip, a first electrode connected to the automatic control circuit, and disposed on at least a first side of the strip, and a second electrode connected to the automatic control circuit and disposed on at least a second side of the strip. The first and second electrodes are placed on one portion or over the entire length of the balance spring in a predetermined angular distribution.