Backlight Driving System Using Constant Current Control
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Solution Overview
Problem
Existing backlight systems using LEDs for LCDs face inefficiencies in brightness control, leading to increased power consumption and heat generation, which shortens LED lifespan and requires additional heat protection, thereby increasing manufacturing costs.
Innovation Solution
A backlight driving system that uses constant currents to control the brightness of red, green, and blue LEDs independently, preventing positive feedback loops that degrade LED performance and reducing power consumption by maintaining consistent current levels regardless of temperature or brightness changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If voltage control method is used to control LED brightness by modulating pulse width, then brightness control is achieved, but power consumption increases and heat generation occurs
Solution Approach 1:
The patent changes the control parameter from voltage (PWM) to current. By using constant current sources that are regulated based on brightness control signals, the system achieves brightness control while maintaining lower and more stable power consumption, as current-regulated LED driving is more efficient than voltage-based PWM control
2Illumination intensity
If voltage control method is used to control LED brightness, then brightness adjustment is possible, but heat generation increases requiring additional heat protection
Solution Approach 1:
The patent switches from voltage-based control to current-based control. Constant current sources regulate the LED current based on brightness control signals, which reduces unnecessary power dissipation and heat generation, eliminating the need for additional heat protection components
3Illumination intensity
If constant voltage is applied to LED for controlled time period, then brightness control is achieved, but LED lifespan is reduced due to heating and degradation
Solution Approach 1:
The patent changes from voltage control with pulse modulation to current control with continuous regulation. By using constant current sources that respond to brightness control signals, the LED operates under more stable electrical conditions with reduced thermal stress, thereby extending LED lifespan while maintaining brightness control capability
Solution Approach 2:
The patent implements feedback mechanisms where constant current sources are regulated based on brightness control signals. This closed-loop current control ensures stable LED operation, prevents overheating, and extends LED lifespan by maintaining optimal current levels regardless of temperature variations
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 enhances the efficiency and uniformity of backlight brightness, reduces power consumption, and extends LED lifespan, minimizing the need for additional heat protection and lowering manufacturing costs.
Implementation Method 1
The light guide plate changes the path of the light exiting from the LED light source so that the light may be akin to light emitted from a surface light source
Implementation Method 2
a liquid crystal layer interposed between the TFT substrate and the color filter substrate which changes the light transmissivity throughout the layer in response to applied electrical signals
Implementation Method 3
a light emitting diode (LED) may be used as the light source
Data Source
AI summary
A liquid crystal display apparatus includes a backlight assembly which includes a device for driving the backlight including a light emitting diode (“LED”) used as a light source, which has a high efficiency and a high reliability for controlling brightness of each color light. The driving device drives a first, second and third LED unit emitting a first, second and third light, respectively. The driving device includes a first driving part emitting the first light in response to a brightness control signal and outputting a reference control signal in response to a first brightness of the first light, a second driving part driving the second LED units generating the second light of which second brightness is controlled in response to the reference control signal, and a third driving part driving the third LED units generating the third light of which third brightness is controlled in response to the reference control signal.