Solutions de rétroéclairage personnalisées & Fournisseur de feuilles optiques – Rnoda Tech
Why TFT LCD Displays Rely on LED Backlighting
TFT LCD (Thin Film Transistor Liquid Crystal Display) does not emit light on its own and has extremely low optical transmittance, typically around 15%. This is because light must pass through multiple layers, including polarizing films, liquid crystal layers, color filter layers, and glass substrates, each of which causes light loss.
So ,the performance of the lebacklight directly determines the brightness, contrast, color uniformity, and image quality of the LCD display.
Classification of LED Backlighting
1. By Light Source Type
RGB-LED Backlight (Full-Color LED Backlight)
Composed of red, green, and blue LEDs, it enables dynamic zone backlighting ,significantly improving color gamut coverage and contrast. Commonly found in high-end televisions, but it’s expensive.
White LED Backlight (White LED)
The most widely adopted led backlight solution, extensively used in laptops, monitors, and televisions. Its color gamut performance is slightly inferior to RGB-LED, but it offers clear advantages in energy efficiency, contrast, and cost.
2. By Light Source Incidence direction
Direct-lit LED Backlight
The light source is located behind the LCD screen, allowing independent control of regional brightness to achieve local dimming, suitable for high-quality displays.
Edge-lit LED Backlight
It relies on a light guide plate (LGP) to evenly diffuse light from LED strips installed along the edges of the screen. This design maintains an ultra-thin profile and is the current mainstream product solution.
Core Components of the led Backlight Module
1. Housing and Bezel
As structural support components of the led backlight module, they are used to secure and protect optical components.
Housings are typically injection-molded plastic parts, while bezels are often stamped metal parts.
Common materials include stainless steel (SUS), cold-rolled steel sheets (SPCC/SECC), aluminum alloy, tinplate, and white brass, among others.
One of the core components of the led backlight, converting point light sources into diffuser light sources.
The surface is covered with laser dots, utilizing optical scattering and total internal reflection principles to achieve uniform light evenly.
Commonly manufactured using etching processes; high-end products may source high-quality LGPs externally.
3. LED Bar / Light Source
LED chips are mounted on PCB or FPC circuit boards and serve as direct light sources.
TFT LCD backlights primarily use white LEDs, while monochrome LCDs may use green or blue LEDs.
Constant current drive design is adopted to prevent uneven LED brightness or reduced lifespan.
4. Optical Films
The “performance-enhancing components” of the led backlight module, primarily consisting of three types:
Film de prisme (BEF, Brightness Enhancement Film)
Utilizes prism structures to enhance central brightness, typically used in pairs to achieve up to 120% brightness improvement.
Distributing light more evenly and prevent bright spots.
Located at the bottom of the led backlight module, it reflects unused light back to the light guide plate to enhance overall brightness.
5. Optical Testing BM-7
The BM-7 optical tester is commonly used to measure backlight brightness, uniformity, and color coordinates，widely recognized as the industry standard in the LCD field.
Testing typically employs a 5-point , 9-point ,13-pointmeasurement method.
Uniformity is generally required to be ≥80%, with special cases requiring ≥70%.
Trends and Summary
RGB-LED direct-lit backlight: offers the best picture quality but is expensive, currently used only in high-end products.
White LED edge-lit backlight: cost-effective and lightweight design, the mainstream solution.
Mini-LED & Micro-LED:The next generation of backlight technology will combine high image quality with cost advantages, and is the direction for future development.
We specialize in providing a wide range of optical products, including light guide plate(LGP), optical films, and complete led backlight solutions. Please contact us for customized optical products and backlight services to ensure the outstanding performance of your display devices.
