Local Dimming with Mini-LED: Superior colour and power efficiency

Local dimming is a technology that enhances contrast and picture quality in LCD displays. Unlike OLEDs, LCD panels cannot emit light themselves and require a backlight, or ambient light to make the screen content visible.

In traditional displays, the backlight is typically edge-lit, producing light output from a single zone across the entire screen. This is referred to as Global Dimming, where brightness adjustments affect the entire display, often resulting in blacks appearing as dark grey due to light leakage.

Local dimming overcomes this limitation by dividing the backlight into multiple zones, each containing many LEDs, with each zone capable of adjusting brightness independently. 

This allows areas of the screen to be dimmed or brightened selectively, enhancing image clarity and contrast. For example, dark areas in a scene can be dimmed, or even turned off completely to achieve deeper blacks, while bright areas can remain vivid. The greater the number of zones, the more targeted the brightness levels in the image can be controlled.

Types of Local Dimming Technologies

Not all local dimming implementations are the same. The choice of technology significantly impacts the display’s performance. There are three primary types:

Edge-Lit Local Dimming

In edge-lit systems, LEDs are positioned along the edges of the backlight unit (top, bottom, or all sides). These LEDs emit light inward through a lightguide and diffuser and can be divided into groups to create dimming zones or individually controlled. While edge-lit systems offer some dynamic backlight control, they lack precision. Light from the edges creates vertical bands of brightness, limiting their ability to accurately dim specific areas of the screen.

Full Array Local Dimming (FALD)

FALD uses a grid of densely packed mini-LEDs, divided into numerous dimming zones. Each zone can be individually controlled to deliver precise brightness levels, resulting in deeper blacks, improved contrast, and superior picture quality. The backlight synchronises with display data, dynamically adjusting zones to match the screen content. This method is ideal for applications requiring high dynamic range (HDR) performance.

Direct-Lit Local Dimming

Direct-lit systems are similar to FALD but use larger LEDs with fewer dimming zones. While they offer better performance than edge-lit systems, they have drawbacks compared to FALD as the limited number of zones reduces precision. Light leakage between zones (blooming) can occur, impacting the overall viewing experience.

image credit: LG

Comparing AMOLED and Mini-LED Local Dimming

AMOLED displays inherently produce light at the pixel level, achieving excellent contrast, deep blacks, and vibrant colours without requiring a backlight, enabling superb picture quality with vibrant colours and deep black backgrounds without the risk of bloom/halo effects. However, AMOLEDs are prone to burn-in when displaying static images and often have shorter lifespans.

In contrast, LCDs with FALD mini-LED backlights rival AMOLED in performance. They deliver wide colour gamuts, vibrant images, and high contrast ratios (up to 1,000,000:1). Additionally, they avoid burn-in, have longer lifetimes, and come with cost advantages, making them a viable alternative for high-performance displays.

Visual and Performance Benefits of Local Dimming

Local dimming greatly enhances contrast by allowing darker areas, for example a night sky, to stay truly black while bright areas, such as fireworks, remain vivid. This precise control improves clarity, depth, and realism while minimising "halo" effects (light bleeding into dark regions), resulting in deeper blacks and more vibrant colours.

Key Benefits of FALD Mini-LED Technology

• Exceptional Contrast: Thousands of dimming zones ensure deep blacks and vibrant colours. This is critical for applications like medical imaging and automotive displays where high contrast and visual clarity are crucial.
• Power Efficiency: Mini-LEDs allow precise brightness control, optimising power consumption, particularly valuable for portable devices where high performance and extended battery life are key.
• Durability and Longevity: Unlike OLEDs, Mini-LEDs resist burn-in and maintain consistent performance over time.

Applications of Mini-LED Technology

Mini-LED backlighting offers wide-ranging industrial applications due to its combination of brightness, contrast control, and energy efficiency:

• Medical Imaging: Enhanced clarity enables professionals to detect fine details, aiding decision-making in critical environments.
• Broadcast and Signage: High dynamic range and sunlight readability make Mini-LED backlighting ideal for outdoor digital signage and studio broadcast monitors.

A Bright Future for Displays

Mini-LED local dimming technology delivers superior brightness, contrast, power efficiency, and durability. With the ability to address limitations of traditional LED and OLED displays, this technology offers engineers a platform to design innovative, future-proof products. Whether for medical, transportation of industrial systems, Mini-LED local dimming sets the stage for the next generation of high-performance displays.

Check out our Mini-LED displays with full array local dimming or contact us to find out more.