Headphone Volume Adjustment via Switched Amplification Paths
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Solution Overview
Problem
Conventional headphones lack an effective method to adjust volume seamlessly when transforming between headphone and speaker forms, potentially leading to undesirable loud sounds in the speaker form.
Innovation Solution
A headphone system with left and right amplifiers, a first switch for directional control, and a second switch for selecting audio signal paths with varying amplification factors, along with a volume adjuster in the digital signal processor (DSP) to manage audio signal volume based on the transformation state, ensuring suitable volume adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the headphone is transformed from headphone form to speaker form, then the speakers are directed in a predetermined direction for better sound projection, but the volume becomes excessively loud
Solution Approach 1:
The patent changes the amplification factor parameter based on the transformation state. When the first switch detects speaker form (speakers directed outward), the system automatically selects the second path with a smaller amplification factor, thereby reducing the volume to appropriate levels while maintaining the directional orientation for sound projection
Solution Approach 2:
The first switch provides feedback about the transformation state to the controller, which then automatically adjusts the audio signal path selection. This closed-loop feedback mechanism ensures that when speakers are directed outward in speaker form, the system responds by reducing amplification to prevent excessive volume
2Power
If the amplification factor is increased for better sound quality in headphone form, then the volume is sufficient for personal listening, but it becomes too loud when transformed to speaker form
Solution Approach 1:
The patent implements dynamic adjustment of the amplification factor based on the real-time transformation state. The second switch dynamically selects between two different amplification paths: the first path with higher amplification for headphone form, and the second path with lower amplification for speaker form, ensuring appropriate volume levels in each configuration
Solution Approach 2:
The system changes the amplification parameter automatically based on the detected form state. When transformed to speaker form, the amplification factor is reduced by switching to the second path, preventing the harmful effect of excessively loud sound while maintaining high amplification benefits during headphone form usage
3Device complexity
If a single audio path is used for both headphone and speaker forms, then the device structure is simple, but the volume cannot be adjusted appropriately for different forms
Solution Approach 1:
The patent makes the audio signal path system multi-functional by providing two different paths through the same amplifiers. The second switch enables the system to universally handle both headphone form (first path with higher amplification) and speaker form (second path with lower amplification), achieving appropriate volume adjustment for each form without requiring separate amplifier circuits
Data Source
AI summary
A headphone includes: a first switch, switched off while at least one of left and right speakers faces inward, and switched on while both speakers face a predetermined direction; left and right amplifiers, amplifying input left and right audio signals and connecting them to the speakers; a second switch, selecting, as a path of the left and right audio signals, either a first path passing through an amplifier or a second path passing through an amplifier and being amplified with an amplification factor smaller than that of the first path; and a volume adjuster, decreasing volume of the left and right audio signals input to the left and right amplifiers in a first state in which the first path is selected and the first switch is off to be less than the volume in a second state in which the first path is selected and the first switch is on.