Series LED Package with Current Adjuster for White Light
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Solution Overview
Problem
Existing backlight units for liquid crystal displays (LCDs) using cold cathode fluorescent lamps (CCFLs) face issues with high voltage requirements, reduced light efficiency due to heat, and environmental concerns from mercury, while LED-based units require complex driver circuits for individual LED control to achieve white balance.
Innovation Solution
A light emitting package with LEDs connected in series and a current adjuster, driven by a single LED voltage generator, which adjusts currents to ensure equal brightness across red, green, and blue LEDs, simplifying the circuitry and reducing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If CCFLs are used as the light source, then high brightness and uniform illumination are achieved, but high voltage is required and mercury is used which is harmful to the environment
Solution Approach 1:
The patent replaces CCFLs with LEDs, which are solid-state light sources without mercury. LEDs have a longer lifespan and are environmentally friendly, eliminating the harmful mercury substance while maintaining brightness through high-efficiency light emission.
Solution Approach 2:
The invention changes the light source parameter from gas discharge (CCFL) to semiconductor electroluminescence (LED). This parameter change eliminates mercury usage while achieving comparable or superior brightness through improved light conversion efficiency.
2Illumination intensity
If CCFLs are used as the light source, then high brightness is achieved, but light efficiency is reduced due to heat generation
Solution Approach 1:
The patent replaces the thermal-mechanical process of CCFLs (heating gas to produce light) with the direct electroluminescence process of LEDs. This substitution eliminates the intermediate heat generation step, directly converting electrical energy to light energy with minimal thermal loss, thereby improving light efficiency while maintaining brightness.
3Illumination intensity
If R, G and B LEDs are individually controlled to achieve white balance, then equal brightness is achieved, but driver circuit complexity increases
Solution Approach 1:
The patent merges the control of R, G, and B LEDs into a single integrated driver circuit that regulates the total current flowing through the series-connected LED string. By controlling the overall current and utilizing the natural spectral composition of the LED combination, the circuit achieves white balance without requiring separate complex driver circuits for each LED color.
Solution Approach 2:
The single driver circuit performs multiple functions: it regulates current for the entire LED string, maintains white balance by controlling the combined spectral output, and simplifies the overall control architecture. This universal circuit replaces what would otherwise require multiple specialized driver circuits.
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 solution allows for the generation of white light with a single driving voltage, reducing the complexity of driver circuits and manufacturing costs, while maintaining equal brightness across LEDs, thus addressing the limitations of CCFL and complex LED driver systems.
Implementation Method 1
a light source 11 with a plurality of R, G and B LEDs
Implementation Method 2
a plurality of light emitting diodes (LEDs) connected in series
Implementation Method 3
a current adjuster coupled with the plurality of LEDs
Data Source
AI summary
A light emitting package is disclosed that can generate a white light while controlling Red, Green and Blue light emitting diodes (“LEDs”) simultaneously. In the light emitting package, a plurality of LEDs are connected in series to one another. The plurality of LEDs are responsive to one driving voltage. Currents flowing through the plurality of LEDs are controlled by a current adjuster. Consequently, the plurality of LEDs are driven by the currents different from one another in amount.