Backlight Module Temperature Control via Local Current Adjustment
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Solution Overview
Problem
Conventional backlight modules experience uneven temperature distribution due to heat accumulation, leading to reduced light emitting efficiency, shortened LED lifespan, and display quality degradation, as the temperature difference between areas affects the driving currents and brightness uniformity.
Innovation Solution
The method involves defining multiple areas in a backlight module, placing temperature sensors near each area, and adjusting the driving currents based on measured temperatures to maintain even temperature distribution, utilizing local dimming capabilities and PWM control to optimize performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the backlight module operates with uniform driving current across all areas, then the light emitting efficiency is maintained, but the temperature distribution becomes uneven causing heat accumulation in the upper area
Solution Approach 1:
The patent applies local quality by dividing the backlight module into multiple areas (first area at top, second area at bottom) and assigning different driving currents to each area. The controller adjusts the driving current of the LED string in the first area to be lower than that in the second area, creating localized current distribution that compensates for the uneven temperature field. This resolves the contradiction by making the current distribution non-uniform to match the temperature distribution, thereby improving overall reliability while maintaining acceptable light emitting efficiency.
Solution Approach 2:
The patent changes the driving current parameter spatially across different areas of the backlight module. By adjusting the driving current based on position (higher in bottom area, lower in top area), the system compensates for temperature differences. This parameter change approach allows the system to operate LEDs in hotter regions at lower currents to extend lifespan, while maintaining sufficient brightness through higher currents in cooler regions.
2Temperature
If the driving current is reduced in the top area to compensate for heat accumulation, then the temperature difference is reduced, but the brightness uniformity deteriorates
Solution Approach 1:
The patent applies local quality by implementing spatially varying driving currents that match the local temperature conditions. The controller selectively adjusts current in the top area versus bottom area, creating localized current compensation that addresses temperature differences without uniformly reducing brightness. This localized approach maintains brightness uniformity by compensating for the current reduction through other means while still achieving temperature balancing.
3Measurement precision
If temperature sensors are added to each area for precise temperature monitoring, then the temperature control precision is improved, but the device complexity increases
Solution Approach 1:
The patent applies partial action by implementing temperature monitoring only in critical areas (at least one sensor in the first area, optionally one in the second area) rather than uniformly distributing sensors across all LED strings. This selective monitoring approach provides sufficient temperature control precision for the most critical regions while avoiding the complexity of comprehensive sensor coverage throughout the entire backlight module.
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 approach significantly reduces temperature differences, enhances brightness uniformity, and extends LED lifespan by ensuring each area operates within optimal temperature ranges, improving overall backlight module performance and power efficiency.
Implementation Method 1
Heat of the backlight is generated when the driver is operating
Implementation Method 2
the light emitting component also generates heat when emitting light
Implementation Method 3
The heat generated within the backlight module causes air convection between the gap. When the air of the lower part of the backlight module is heated due to the heat generated from the light emitting component and the driver, the air convection causes the hot air to flow upwards
Data Source
AI summary
A method of determining driving currents of a backlight module includes: disposing the backlight module onto a base; defining a plurality of areas from a top area to a bottom are of the backlight module; and reducing the driving current of the area that is situated further from the base.