Quartz Resonator Load Sensor Structure to Prevent Buckling
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Solution Overview
Problem
Load sensors using quartz crystal resonators face challenges with bending stress, leading to buckling and reduced resolution when measuring large loads, as they are weak against bending stress due to their shape, requiring techniques to stabilize the resonator while maintaining detection range.
Innovation Solution
A load sensor design featuring a sheet-shaped quartz crystal resonator with holding layers that restrain deformation, bonded via adhesive layers, to prevent buckling and allow for a wider measurement range without compromising resolution, with the holding layers and resonator having common thermal expansion characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the thickness of the sheet-shaped quartz crystal resonator is reduced to widen the measurement range, then the detection range is widened, but the resonator becomes more susceptible to buckling under bending stress
Solution Approach 1:
The resonator is divided into a measurement portion and holding portions, with the holding portions extending beyond the measurement portion to provide structural support and prevent buckling while maintaining a thin profile for the measurement area
Solution Approach 2:
The holding portions extend in the planar direction beyond the measurement portion, utilizing the planar dimension to provide structural support rather than increasing thickness, thus preventing buckling without compromising the widened measurement range achieved through reduced thickness
2Reliability
If holding structures are added to prevent buckling of the quartz crystal resonator, then buckling resistance is improved, but the device complexity increases
Solution Approach 1:
The holding portions are integrated as integral parts of the quartz crystal resonator itself, merging the structural support function with the resonator body to avoid adding separate holding structures and thus preventing increase in device complexity
Solution Approach 2:
The holding portions serve multiple functions: they provide buckling resistance, maintain structural integrity, and enable the thin-profile design of the measurement portion, achieving multiple objectives through a single structural feature
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 design effectively suppresses buckling, enabling a reduced thickness of the quartz crystal resonator, widening the measurement range while maintaining high resolution and stability across varying environmental temperatures.
Implementation Method 1
a load sensor described in Patent Document 1... based on the fact that when a load is applied to the quartz crystal resonator formed into a sheet shape, the oscillating frequency thereof varies precisely in proportion to the applied load
Implementation Method 2
a load sensor measuring a load by a change in oscillation frequency of a crystal (quartz) blank due to stress sensibility against thereof when a load is applied
Implementation Method 3
the quartz crystal resonator layer is restrained from deforming toward both side of the sheet shape by the 1 pair of holding layers, so that buckling of the quartz crystal resonator layer can be prevented
Implementation Method 4
the holding layers and the quartz crystal resonator layer have common thermal expansion characteristics regardless of an environmental temperature at which the load sensor is placed
Data Source
Figure 1(a)~1(c)
Figure 2
Figure 3(a)~3(h)
AI summary
Provided is a load sensor using a quartz crystal resonator having a widened detection range while maintaining a resolution. A load sensor 10 comprises a quartz crystal resonator layer 12 including a sheet-shaped quartz crystal resonator 16 and a pair of electrode portions 18 on a pair of surfaces of the quartz crystal resonator 16 opposite to each other in a plate thickness direction of the quartz crystal resonator 16, and at least one holding layer 14 causing a displacement in substantially the same amount as the quartz crystal resonator layer 12 when an external load is applied to the quartz crystal resonator layer 12, and therefore, in a case where an external load is applied in the direction parallel to the sheet shape of the sheet-shaped quartz crystal resonator 16, deformation of the quartz crystal resonator 16 in the bending direction is suppressed by holding layer 14, so that buckling of the quartz crystal resonator 16 can be prevented. Therefore, the thickness of the sheet-shaped quartz crystal resonator 16 can be reduced, and the measurement range can be widened.