Backlight Unit Auxiliary LED for EEFL Initial Lighting Failure
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Solution Overview
Problem
Initial driving malfunctions occur in backlight units, particularly in large LCD devices using external electrode fluorescent lamps (EEFLs), when left in darkness or at low temperatures, causing the lamps to fail to light up upon initial operation.
Innovation Solution
Incorporating an auxiliary light source, such as a light-emitting diode (LED), on the driver PCB within the backlight unit, along with micro-penetration holes or slit holes on the reflective sheet, which allows partial irradiation of light from the auxiliary source to the lamps, ensuring they start correctly even in darkness or low temperatures, thereby preventing initial driving malfunctions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If EEFLs are used as the light source in the backlight unit, then the lifespan is extended, but initial driving malfunctions occur when the device is left in darkness or at low temperatures
Solution Approach 1:
The patent introduces an auxiliary light source that activates before the main EEFLs to pre-heat the gas inside the lamps and restore it to an excitable state. This preliminary action ensures that when the main lamps are turned on after being in darkness or low temperature, the gas is already in a suitable state for immediate lighting, preventing initial driving malfunctions while maintaining the long lifespan benefit of EEFLs.
2Reliability
If the auxiliary light source is added to prevent initial driving malfunction, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The patent merges the auxiliary light source with the existing driver circuitry and integrates it into the same backlight unit structure. The auxiliary light source is positioned to share the same housing and optical path considerations as the main EEFLs, combining multiple functions into a unified assembly rather than adding a completely separate system, thus minimizing the increase in device complexity.
Solution Approach 2:
The driver circuitry is designed to control both the auxiliary light source and the main EEFLs, making the control system multi-functional. The same driver that manages the primary lighting function also handles the preliminary heating function, reducing the need for separate control circuits and minimizing overall system complexity while improving reliability.
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 prevents initial driving malfunctions and improves the uniformity and quality of the displayed image by ensuring the lamps operate correctly, maintaining brightness consistency across the display.
Implementation Method 1
an auxiliary light source loaded on the driver; a first hole formed in a region of the bottom cover opposite to the auxiliary light source; and a hole region, on the reflective sheet, including one of plural micro-penetration holes and plural slit holes and opposite the first hole on the reflective sheet
Implementation Method 2
a reflective sheet disposed in the inner surface of the bottom cover
Data Source
AI summary
A backlight unit which prevents an initial driving malfunction is disclosed. The backlight unit includes: a bottom cover opened upwardly; a reflective sheet disposed in the inner surface of the bottom cover; a plurality of lamps arranged in a fixed interval on the reflective sheet; a driver disposed on the rear surface of the bottom cover; an auxiliary light source loaded on the driver; a first hole formed in a region of the bottom cover opposite to the auxiliary light source; and a hole region, on the reflective sheet, including one of plural micro-penetration holes and plural slit holes and opposite the first hole on the reflective sheet.