Dynamic Bias Voltage Adjustment for LED Backlight Drivers
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Solution Overview
Problem
Existing backlighting technologies for LCD displays face challenges in reducing power consumption, heat dissipation, and cost, particularly due to string-to-string voltage mismatches in white LEDs, which necessitate expensive binning processes to manage power dissipation.
Innovation Solution
A backlight driver system that dynamically adjusts the bias voltage of current sources connected to LED strings based on voltage drops across each string, using a combination of current sources, multiplexing blocks, and voltage generators to minimize power consumption and heat, allowing for the use of unbinned LEDs and reducing system costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional backlighting technology is used with fixed current sources for LED strings, then the circuitry is simple, but power consumption and heat dissipation are high due to string-to-string voltage mismatches
Solution Approach 1:
The patent implements dynamic adjustment of current source bias voltages based on measured LED string voltage drops. The system transitions from fixed bias voltages to variable bias voltages that adapt to individual string characteristics, thereby reducing power consumption while managing circuit complexity through controlled adaptability
Solution Approach 2:
The patent changes the bias voltage parameter of current sources according to the voltage drop characteristics of each LED string. By adjusting this critical parameter dynamically, the system optimizes power consumption and heat dissipation without requiring complete redesign of the driving circuitry
2Ease of manufacture
If conventional backlighting technology is used with fixed current sources for LED strings, then the manufacturing process is simple, but expensive binning processes are required to manage power dissipation
Solution Approach 1:
The system enables self-adjustment of power distribution by measuring actual LED string voltage drops and automatically selecting appropriate bias voltages. This eliminates the need for manual binning processes, allowing unbinned LEDs to be used directly while optimizing power dissipation for each string
Solution Approach 2:
The patent incorporates feedback mechanisms where the voltage drop across each LED string is measured and used to determine the optimal bias voltage for its current source. This closed-loop approach eliminates the need for expensive binning while effectively managing power dissipation
3Temperature
If conventional backlighting technology is used, then the circuit design is straightforward, but heat dissipation is high
Solution Approach 1:
The patent implements dynamic adjustment of current source bias voltages based on measured LED string voltage drops. The system transitions from fixed bias voltages to variable bias voltages that adapt to individual string characteristics, thereby reducing power consumption and heat dissipation while managing circuit complexity through controlled adaptability
Solution Approach 2:
The patent changes the bias voltage parameter of current sources according to the voltage drop characteristics of each LED string. By adjusting this critical parameter dynamically, the system optimizes power consumption and heat dissipation without requiring complete redesign of the driving circuitry
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 system effectively reduces power consumption and heat dissipation by optimizing voltage distribution across LED strings, eliminating the need for costly binning and enabling the use of less expensive, unbinned LEDs, thereby lowering overall system costs and improving performance.
Implementation Method 1
reduce a current drop across the current source. This reduces the power consumption of the current source and LED string
Implementation Method 2
A backlight driver includes current sources that are connected between LED strings and a number of bias voltages
Data Source
AI summary
A backlight driver includes current sources that are connected between LED strings and a number of bias voltages. There can be any number of different bias voltages, each at a ground potential or higher voltage. The bias voltage is selected for a particular LED string in order to reduce a current drop across the current source. This reduces the power consumption of the current source and LED string. Heat dissipation is also reduced.