Telephone Handset Coupling Slots at Joining Edge
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Solution Overview
Problem
Telephone handsets for broadband communication systems face challenges in achieving a wide frequency spectrum transmission while minimizing sound leakage and maintaining design freedom, as existing coupling slots on the back of the handset lead to unwanted sound emission and eavesdropping issues.
Innovation Solution
The coupling slots are relocated to the joining edge between the upper and lower shells, allowing acoustic coupling with the external field while minimizing sound leakage by positioning them near the loudspeaker and maintaining optical design flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If coupling slots are arranged on the back of the telephone handset, then acoustic coupling with the free field is achieved and wide frequency spectrum transmission is enabled, but sound leakage increases and immunity from eavesdropping deteriorates
Solution Approach 1:
The coupling slots are relocated from the back surface (2D plane) to the joining edge (1D linear feature), changing the spatial dimension and configuration. This dimensional transition allows acoustic coupling while preventing sound leakage by positioning slots at the peripheral edge rather than the central back surface.
Solution Approach 2:
The joining edge region is given a special local function by incorporating coupling slots, differentiating it from the rest of the housing. This localized acoustic coupling approach concentrates the acoustic function at the edge while maintaining sound isolation at the back surface.
2Reliability
If coupling slots are provided on the back of the telephone handset, then frequency spectrum transmission down to 1 Hz is achieved, but design freedom and optical configuration are restricted
Solution Approach 1:
By moving coupling slots from the back surface to the joining edge, the design maintains full flexibility in back surface configuration while achieving acoustic coupling through the edge geometry, thereby preserving design freedom.
Solution Approach 2:
The joining edge serves multiple functions: structural connection between upper and lower shells, and acoustic coupling interface with the free field. This multi-functionality eliminates the need for separate back surface openings, maintaining design flexibility.
3Reliability
If coupling slots are arranged on the back of the telephone handset, then resonance volume coupling is achieved, but noise annoyance and eavesdropping risk increase in call center installations
Solution Approach 1:
The coupling slots are extracted from the back surface location and relocated to the joining edge, removing the source of sound leakage and eavesdropping risk while preserving the acoustic coupling function.
Solution Approach 2:
The joining edge, which is necessarily present due to construction requirements, is converted into a beneficial acoustic coupling feature by incorporating coupling slots, turning a structural necessity into a functional advantage while avoiding sound leakage.
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 arrangement ensures effective acoustic coupling for a wide frequency spectrum transmission with reduced sound leakage, enhancing immunity from eavesdropping and preserving design freedom, thereby improving both functionality and aesthetics.
Implementation Method 1
These coupling slots connect the resonance volume inside the telephone handset with the free field outside the telephone handset. This coupling of the resonance volume with the outer air space makes it possible to enlarge the resonance volume in a simple manner.
Implementation Method 2
a resonance volume is usually provided inside the telephone handset in the area of the loudspeaker, because the acoustic signal of the voice message is amplified by resonance in the corresponding frequencies
Data Source
AI summary
A telephone handset for a broadband telecommunication system, whose housing is composed of an upper shell and a lower shell forming a joining edge, shall guarantee a reliable coupling of the resonance volume to the free field with a particularly low sound leakage. For this purpose, the joining edge is provided according to the invention with a number of coupling slots.