Playback Device Switch Circuit Pop Noise Control
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Solution Overview
Problem
Existing playback devices generate pops due to surges when the control chip starts or stops outputting audio signals, and using a processing circuit to mitigate this issue increases power consumption and introduces noise in single-ended speaker modes.
Innovation Solution
A playback device comprising a speaker, a controller, and switch circuits that control the transmission of audio signals, allowing the speaker to operate in differential mode by turning the switch circuits on and off according to control signals, thereby avoiding pops and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a processing circuit is disposed between the control chip and the speaker to resolve pops, then pop noise is reduced, but power consumption increases due to the complex processing circuit composed of multiple components
Solution Approach 1:
The patent extracts and removes the complex processing circuit from the system, replacing it with a simplified switch circuit that achieves the same pop noise reduction function with fewer components, thereby reducing power consumption while maintaining the ability to prevent pop noise during audio signal transitions
Solution Approach 2:
The patent changes the operational parameters of the speaker by controlling the switch circuit to adjust the impedance and signal transmission characteristics dynamically, enabling pop noise reduction without requiring a complex processing circuit, thus lowering power consumption
2Device complexity
If the speaker operates in a single-ended mode where one terminal is grounded, then circuit complexity is reduced, but noise levels increase
Solution Approach 1:
The patent implements a dynamic switching mechanism that allows the speaker to operate in different modes (single-ended or differential) based on operational requirements. The switch circuit dynamically reconfigures the speaker connections, providing low noise performance when needed while maintaining circuit simplicity, thus resolving the contradiction between complexity and noise
3Duration of action of moving object
If the switch circuit is turned on immediately when the controller outputs the audio signal, then signal transmission is continuous, but pops are generated due to surge at the moment the control chip starts outputting
Solution Approach 1:
The patent applies preliminary action by controlling the switch circuit to be turned on at a precisely timed moment after the controller outputs the audio signal, rather than immediately. This timing control prevents the switch circuit from being active during the surge moment when pop noise is generated, while still maintaining continuous signal transmission for the duration of the audio output
Solution Approach 2:
The patent implements preliminary anti-action by using the switch circuit to block or prevent the surge signal from reaching the speaker during the initial moment when pop noise would occur. The control signal is designed to activate the switch circuit in a way that counteracts the harmful surge effect before it can cause pop noise, while allowing normal signal transmission to proceed
Data Source
AI summary
A playback device includes a speaker, a controller, a first switch circuit, and a second switch circuit. The speaker has a first terminal and a second terminal. The controller is configured to output a first audio signal and a second audio signal. The controller is coupled to the first terminal of the speaker, and is configured to transmit the first audio signal to the speaker. The second switch circuit is coupled between the second terminal of the speaker and the controller, and is coupled to the first switch circuit. The second switch circuit is configured to transmit the second audio signal from the controller to the speaker when the first switch circuit is turned on.