Eliminating hotspots in a multi-chip LED array direct backlight system with optimal patterned reflectors for uniform...

Area of Science:

• Optics and Photonics
• Display Technology
• Materials Science

Background:

• Direct backlight units (BLUs) are crucial for display technologies.
• Current BLU development can be time-consuming and costly.
• Optimizing BLU design for thickness and uniformity is a key challenge.

Purpose of the Study:

• To propose an efficient optical design process for direct backlight units (BLUs).
• To reduce development time and costs associated with BLU creation.
• To achieve target luminance and uniformity while minimizing system thickness.

Main Methods:

• Deriving system specifications from RGB light-emitting diode (LED) optical characteristics.
• Estimating driving currents to determine theoretical RGB flux ratios for desired white points.
• Calculating the number of LEDs based on component optical efficiencies and target luminance.
• Determining array configuration using illuminance distribution functions for uniformity.
• Evaluating system thickness with flat and patterned reflective sheets.

Main Results:

• A design process was established and demonstrated on 42-inch BLUs with 40 x 16 LED elements.
• A minimum system thickness of 30 mm was required for target uniformity with a flat reflective sheet.
• A patterned reflective sheet effectively eliminated hotspots, enabling reduced system thickness.
• An optimized patterned reflective sheet allowed for a system thickness reduction of up to 5 mm.

Conclusions:

• The proposed optical design process significantly streamlines BLU development.
• Patterned reflective sheets offer a viable method for reducing BLU thickness without additional optical components.
• This approach contributes to more efficient and cost-effective display manufacturing.