Ultrasonic Sensor Recessed Base for Directivity Control
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Solution Overview
Problem
Existing ultrasonic sensors face variations in ultrasonic-wave transmitting/receiving characteristics due to adhesive bonding inconsistencies, complex metallic case manufacturing, and oxidation, which affect directivity and reliability.
Innovation Solution
An ultrasonic sensor design featuring a piezoelectric element accommodated in a base with a recessed portion and covered by an outer casing, where the piezoelectric element is accurately positioned to reduce variations, and a weight with a depressed portion is used to control directivity and suppress unnecessary vibrations, eliminating the need for adhesive bonding and metallic cases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If adhesive bonding is used to attach the piezoelectric element to the case, then the assembly is simplified, but variations in bonding amount and position cause variations in ultrasonic-wave transmitting/receiving characteristics
Solution Approach 1:
The patent removes the adhesive bonding step entirely by designing a recessed portion in the case that mechanically retains the piezoelectric element. This extraction of the adhesive function eliminates the harmful variations in bonding characteristics while maintaining ease of assembly through simple mechanical fitting.
Solution Approach 2:
The case structure itself provides the positioning and retention function through the recessed portion, eliminating the need for external adhesive. The recessed portion automatically ensures consistent positioning of the piezoelectric element, making the system self-positioning and self-retaining.
2Strength
If a metallic case is used to achieve desired directivity, then the structural strength is improved, but the case may be oxidized and manufacturing becomes complicated
Solution Approach 1:
The patent replaces the expensive, complex metallic case with a simpler, oxidization-resistant material case. The recessed portion design maintains the necessary structural function without requiring complex metal forming processes, thereby reducing manufacturing complexity and cost.
Solution Approach 2:
The patent changes the material parameter of the case from metal to oxidization-resistant material, fundamentally altering the chemical properties to eliminate oxidation issues. The structural parameters are maintained through the recessed portion design that provides mechanical retention.
3Volume of moving object
If the piezoelectric element is bonded to the case surface, then the assembly is compact, but oxidation at the bonding portion causes variations in characteristics
Solution Approach 1:
The patent extracts the piezoelectric element from direct contact with the case surface by placing it in a recessed portion. This separation eliminates the oxidation-prone bonding interface while maintaining compactness through the integrated recessed design that keeps the element within the case volume.
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 stabilizes transmitting/receiving characteristics, achieves desired directivity at a lower cost, and improves sound pressure and sensitivity by ensuring precise positioning and vibration control, while simplifying manufacturing and reducing material costs.
Implementation Method 1
the piezoelectric element 3 is driven by applying driving voltages to the signal lines 4a and 4b of the cable 4
Implementation Method 2
the piezoelectric element 3 vibrates. The vibration is converted into electrical signals
Implementation Method 3
the bent portion extending inward from a first opening of the side portion... bending vibration occurs in the outer casing during driving
Data Source
AI summary
An ultrasonic sensor with stabilized transmitting/receiving characteristics capable of achieving a desired directivity easily and at low cost and a method for manufacturing the same are provided. The ultrasonic sensor includes a base composed of a synthetic resin. The base includes a cylindrical side portion and a ring-shaped bent portion extending inward from a first opening of the side portion. A ring-shaped recessed portion is provided in the inner surface of the bent portion adjacent to the end of the bent portion. A piezoelectric element is disposed on the recessed portion. A sound absorber and a weight are fitted and fixed in the base. An outer casing composed of a synthetic resin is provided so as to cover the outer surface of the piezoelectric element and the outer surface of the base.