Backlight Dimming Circuit Reducing Acoustic Noise
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Solution Overview
Problem
Acoustic noise generated by backlight modules with organic light-emitting diodes in electronic devices is a disturbance that requires individual adjustment, consuming labor, time, and money.
Innovation Solution
A dimming circuit that includes a control unit, sampling analysis unit, pulse width signal adjusting unit, and analog dimming circuit, which determines the duty ratio of a pulse width modulation signal to transform or adjust the signal and current accordingly, reducing acoustic noise by frequency conversion and phase shift or adjusting the dimming current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If individual adjustment or modification is performed to address acoustic noise in backlight modules, then the acoustic noise problem is solved, but labor, time, and money are consumed in large amounts
Solution Approach 1:
The backlight module performs self-diagnosis and self-adjustment through the control unit that automatically detects acoustic noise levels and adjusts PWM signal parameters without requiring manual intervention. The system monitors itself and makes real-time corrections to eliminate noise
Solution Approach 2:
The system implements a feedback mechanism where the control unit continuously monitors the backlight module's operation, detects acoustic noise generation, and automatically adjusts PWM duty ratio or frequency in response to the detected noise levels, creating a closed-loop control system
2Object-affected harmful factors
If individual adjustment or modification is performed to address acoustic noise in backlight modules, then the acoustic noise problem is solved, but labor and money are consumed in large amounts
Solution Approach 1:
The control unit is designed with multi-functionality, serving both as the primary control element for backlight operation and as an acoustic noise detection and adjustment unit. This universal component eliminates the need for separate noise-adjustment hardware, reducing manufacturing costs
Solution Approach 2:
The system eliminates the need for manual adjustment procedures by implementing automatic noise detection and correction capabilities within the existing control unit, thereby removing the need for additional labor and associated costs during manufacturing and deployment
3Use of energy by moving object
If PWM signal duty ratio is reduced to dim the backlight, then power consumption is reduced, but acoustic noise may be generated
Solution Approach 1:
The control unit dynamically changes PWM signal parameters (duty ratio, frequency) based on operational conditions. When acoustic noise is detected during dimming operations, the system adjusts the frequency parameter while maintaining the reduced duty ratio, thereby preserving low power consumption while eliminating noise
Solution Approach 2:
The system dynamically adjusts PWM parameters in real-time based on feedback from acoustic noise detection. Rather than using fixed dimming parameters, the control unit continuously optimizes the PWM signal characteristics to maintain both low power consumption and low noise operation
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
The dimming circuit effectively reduces or eliminates acoustic noise in backlight modules by dynamically adjusting the pulse width modulation signals and currents based on the duty ratio, improving user experience and reducing design and operational costs.
Implementation Method 1
the pulse width signal adjusting unit transforms the first pulse width modulation signal to a second pulse width modulation signal by a frequency conversion and a phase shift
Implementation Method 2
the pulse width signal adjusting unit transforms the first pulse width modulation signal to a second pulse width modulation signal by a frequency conversion and a phase shift
Implementation Method 3
A light-emitting diode backlight module is often used in the electronic products
Data Source
AI summary
A dimming method is provided. The dimming method includes steps as follows: determining whether a duty ratio of a first pulse width modulation signal is larger than a threshold duty ratio; when the duty ratio of the first PWM signal is smaller than the threshold duty ratio, the first pulse width modulation signal is transformed to a second pulse width modulation signal by a frequency conversion and a phase shift according to a pulse information signal, when the duty ratio of the first pulse width modulation signal is larger than the threshold duty ratio, adjusting a predetermined dimming current according to the pulse information signal, wherein the threshold duty ratio is set according to a number of the channel and the predetermined dimming current.