Earphone Back Cavity and Weighted Ring for Sound Quality
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Solution Overview
Problem
The challenge is to minimize sound quality loss in earphones with audio output units located inside the external auditory canal, where smaller units lead to increased difficulty in producing high-quality sound due to space constraints.
Innovation Solution
The design incorporates a cylindrical portion with a back cavity and a sound absorbing material, along with a metal unit holder and a ring of greater specific gravity, to reduce sound loss and enhance sound quality by compensating for the limitations of smaller driver units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the audio output unit is made smaller to fit inside the external auditory canal, then the earphone can be inserted in the external auditory canal, but the sound quality deteriorates
Solution Approach 1:
The patent changes the physical parameters of the earphone structure by introducing a back cavity with specific volume and shape, and positioning the audio output unit at a specific distance from the eardrum. This allows optimization of acoustic parameters (sound pressure distribution, resonance characteristics) to maintain sound quality despite the small size of the audio output unit
Solution Approach 2:
The patent utilizes the spatial dimension by creating a back cavity that extends along the insertion direction, effectively using the depth dimension of the ear canal to provide acoustic volume. This allows the system to achieve adequate sound quality without increasing the radial size of the audio output unit
2Reliability
If sound absorbing material is added to the back cavity to improve low-tone output, then sound quality improves, but the device complexity increases
Solution Approach 1:
The patent introduces sound absorbing material with porous structure into the back cavity. This material absorbs excess acoustic energy and controls resonance, particularly improving low-tone output. The porous structure provides acoustic functionality without requiring complex mechanical components
Solution Approach 2:
The patent adopts a simplified approach by using a basic back cavity structure that naturally provides acoustic volume, rather than implementing complex active noise control systems or multiple acoustic chambers. The solution copies the essential acoustic volume requirement in a simplified geometric form
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
This configuration effectively suppresses sound quality loss, particularly in low-tone outputs, while maintaining a compact earphone design that fits within the auditory canal, ensuring clear and crisp sound reproduction.
Implementation Method 1
a sound absorbing material (174) is placed in a space (BC) between the another face (130b) of the audio output unit (130) and the bottom face (116p)
Implementation Method 2
a ring (176), made of a material of a greater specific gravity than the cylindrical portion (116a)
Data Source
AI summary
An earphone includes a cylindrical portion having an opening in one end and an audio output unit which outputs sound from one face. The audio output unit is fixed to the cylindrical portion such that another face is in contact with an end face of the one end of the cylindrical portion. The audio output unit and the cylindrical portion are insertable at least partially in the external auditory canal of a human being. The earphone further includes a thin-wall part provided in the cylindrical portion and a ring, made of a material of a greater specific gravity than the cylindrical portion, which is fixed to the inner surface. The ring is fixed in a position such that the ring overlaps in the axial direction of the cylindrical portion with respect to the thin-wall part.