Bone Conduction Vibrator Accelerometer Countermass
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Solution Overview
Problem
Existing bone-conduction hearing devices lack precision in determining the vibrational force applied to the skull bone, which is crucial for calibrating and operating these devices, especially due to uncertainties in mechanical impedance changes over time and variations in tissue and bone structure.
Innovation Solution
A device comprising a vibration element, a motor, a countermass, a retaining element, and an accelerometer, where the accelerometer is connected to the countermass to provide an acceleration signal, allowing precise determination of the vibrational force by calculating the force acting on the skull bone through mechanical circuit analysis and dimensioning components to minimize interference from other mechanical admittances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an accelerometer is attached to the vibration element to measure vibrational acceleration, then measurement capability is provided, but measurement precision deteriorates due to unknown and changing mechanical impedance of the coupling
Solution Approach 1:
The patent introduces a countermass as an intermediary element that does not couple directly to the skull bone. The accelerometer is attached to the countermass, which is connected to the vibration element through a spring. This intermediary system allows measurement of vibrational parameters without direct contact between the measurement device and the bone, eliminating the problem of unknown and changing mechanical impedance at the bone interface.
Solution Approach 2:
The patent divides the measurement system into separate functional components: the vibration element that contacts the bone, the spring that provides mechanical coupling, and the countermass with accelerometer that performs measurement. This segmentation isolates the accelerometer from the variable mechanical impedance of the bone-tissue-coupling system, allowing reliable measurements regardless of changes in the bone interface conditions.
2Ease of operation
If the accelerometer is attached to the vibration element, then direct measurement is achieved, but the correlation between accelerometer output and applied vibrational force lacks precision
Solution Approach 1:
The countermass serves as an intermediary that decouples the accelerometer from the vibration element's direct interaction with the bone. The accelerometer measures the motion of the countermass, which is mechanically linked to the vibration element through the spring. This allows the system to maintain ease of operation while achieving precise correlation between accelerometer output and applied vibrational force through the known mechanical relationship of the spring-countermass system.
3Adaptability or versatility
If materials and tissue structure change over time, then adaptability to biological changes occurs, but measurement reliability deteriorates due to aging effects
Solution Approach 1:
The spring-countermass assembly acts as a buffer between the vibration element and the accelerometer, isolating the measurement system from biological changes in the bone and tissue. While the vibration element must maintain contact with the bone for effective vibration transmission, the accelerometer measures the motion of the countermass whose mechanical properties remain stable over time, ensuring consistent measurement reliability despite aging of biological tissues.
Solution Approach 2:
By separating the measurement function (accelerometer on countermass) from the bone interface function (vibration element), the patent allows the bone-contacting components to adapt to biological changes while the measurement components remain in a controlled, stable environment. This segmentation protects the measurement system from degradation due to tissue aging and bone structure changes.
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 and reproducible determination of vibrational force, improving the calibration and operation of bone-conduction hearing devices and allowing for accurate bone-conduction hearing threshold assessments.
Implementation Method 1
the motor (12, 13) being adapted to cause the vibration element (10) and the countermass (11) to vibrate relative to each other
Implementation Method 2
an accelerometer (21), the accelerometer (21) being mechanically connected to the countermass (11), such that it moves together with the countermass (11), and being adapted to provide an acceleration signal representative of an acceleration of the countermass (11)
Implementation Method 3
the vibration element (10) being adapted to transmit vibrations to a fixture (4) osseointegrated in the skull bone (2)
Data Source
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AI summary
Hearing losses caused by deficiencies in a person's outer or middle ear may be compensated for by converting received sounds to vibrations and transmitting the vibrations to the skull bone (2). Bone-conduction hearing devices (27) may transmit such vibrations transcutaneously or percutaneously. In both cases, a precise determination of the magnitude of the vibrations applied to the skull bone (2) is needed for determining the person's bone-conduction hearing thresholds as well as for calibrating the hearing devices (27). The present invention provides a device (1, 27, 37) and a method, which allow determination of the applied vibrational force with better precision than prior art devices and methods. This is achieved by placing an accelerometer (21) on the countermass (11) of the vibrator (1) that generates the vibration signal. The accelerometer (21) thus provides an acceleration signal representative of an acceleration of the countermass (11), from which acceleration signal the vibrational force may be determined precisely and reproducibly.