Ultrasonic Lamb Wave Weighing Scale for Uneven Surfaces
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Solution Overview
Problem
Thin electronic scales face inaccuracies in weight measurement when placed on deep carpet or uneven floors due to insufficient clearance, leading to mechanical issues and rubbing between components, which complicates the use of load cells and results in incorrect readings.
Innovation Solution
A weighing device with a sensory plate and a top plate separated by spacer pads, utilizing emission and reception transducers to generate and receive Lamb waves, allowing for weight determination through analysis of the temporal profile of echoed waves without the need for load cells, resulting in a simplified and cost-effective mechanical configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the thickness of the scale is decreased, then the device becomes thinner and more compact, but the clearance between the bottom plate and floor becomes insufficient when placed on deep carpet or uneven floors, leading to inaccurate weight measurements
Solution Approach 1:
The patent replaces the traditional mechanical load cell system with an ultrasonic wave-based measurement system. Lamb waves are generated in the sensory plate and their propagation characteristics are analyzed to determine weight, eliminating the need for mechanical load cells and their associated clearance requirements. This substitution allows the scale to be made thinner while maintaining measurement accuracy on various surfaces.
Solution Approach 2:
The sensory plate serves multiple functions: it acts as both the structural base plate and the ultrasonic wave propagation medium. The same plate that provides structural support also serves as the medium for generating and detecting Lamb waves, enabling weight measurement without requiring additional clearance-generating components.
2Measurement precision
If load cells are used in a thin scale configuration, then weight measurement is enabled, but the mechanical configuration becomes complex and prone to rubbing between components
Solution Approach 1:
The patent replaces the mechanical load cell system with an ultrasonic wave-based measurement system. Instead of using mechanical deformation of load cells to measure weight, the system generates Lamb waves in the sensory plate and analyzes changes in wave propagation caused by the applied load. This eliminates the mechanical rubbing issues and simplifies the overall device structure.
Solution Approach 2:
The sensory plate acts as an intermediary medium that translates mechanical load into ultrasonic wave propagation changes. Rather than directly measuring force through mechanical load cells, the plate's response to applied weight is captured through ultrasonic wave analysis, providing a non-contact, friction-free measurement mechanism.
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 the creation of a very thin weighing device with improved accuracy and reduced cost, capable of precise weight measurement on various surfaces, including deep carpet and uneven floors, with a thickness of less than 18 mm, and offers additional features for user-friendly operation and heart rate analysis.
Implementation Method 1
a sensory plate (1), fitted with at least an emission transducer (11,Tx) configured to generate, on a periodic basis, a burst of Lamb waves (6) at the surface of the sensory plate
Implementation Method 2
the sensory plate is fitted with at least a reception transducer (12;13,14), configured to receive echoed Lamb waves (7) propagated through the sensory plate
Implementation Method 3
an emission transducer (11,Tx) configured to generate, on a periodic basis, a burst of Lamb waves (6)
Data Source
Figure 1~3
Figure 4~6
Figure 7A~7C
AI summary
A weighing device, configured to measure at least the weight of a person or an object, comprising a control unit (3), a sensory plate (1), a top plate (2), spacer pads (9), interposed between the plates,wherein the sensory plate has an emission transducer (11, Tx) configured to generate, a burst of Lamb waves (6) at the surface of the sensory plate, a reception transducer (12; 13, 14), to receive echoed Lamb waves (7) propagated through the sensory plate, the temporal profile of the echoed Lamb waves being dependent on the weight (P) applied to the top plate and passed by the spacer pads to the sensory plate, wherein the control unit determines the weight applied to the top plate by analysis of the temporal profile of the echoed Lamb waves.