What is an LED video display?

1.1 A direct-view, self-emissive display

This is different from an LCD. An LCD controls light from a separate backlight; a direct-view LED display emits light at the image surface. It is also different from projection, where an optical system throws an image onto a separate surface. The self-emissive approach supports high luminance, strong visibility in bright environments and modular construction.

The US Department of Energy's LED basics gives a concise explanation of solid-state light production. In a video display, that principle is repeated across thousands or millions of individually controlled light-emitting elements.

1.2 The modular hierarchy

Although designs vary, most large-format LED displays can be understood as a hierarchy:

• A subpixel is a red, green or blue light-emitting element.

• A pixel combines the primary colours into one addressable picture element.

• A module is a repeated matrix of pixels on a circuit assembly.

• A cabinet provides a mechanical and electronic building block containing one or more modules.

• The display is the complete canvas formed from multiple cabinets or, in some products, larger integrated units.

Enlarge diagram

Scroll across the enlarged diagram to read its labels.

Figure 1. From subpixels to a complete LED video display.

This hierarchy explains why a display can be made to a non-standard size. The physical canvas is assembled from repeated building blocks, while the control system maps the video image across the resulting pixel matrix.

1.3 Why LED displays can be very large

Conventional flat panels are manufactured as complete glass-based units and are constrained by panel sizes, transport and visible joins when tiled. LED cabinets can be combined in rows and columns with no bezel in the active image area. The overall canvas can therefore be wide, tall, curved or creatively shaped, subject to the product's geometry and the engineering of the supporting structure.

Modularity does not automatically make every join invisible. Cabinet flatness, manufacturing tolerances, mechanical alignment, optical uniformity and viewing angle all affect whether boundaries can be seen. A seamless appearance is an outcome of the complete system, not simply the absence of a conventional bezel.

1.4 What an LED display is not

The market uses the letters "LED" for several different technologies:

• An LED television is usually an LCD television with an LED backlight.

• MiniLED backlighting uses a dense array of small LEDs behind an LCD to improve local dimming; it is not necessarily a direct-view LED image surface.

• OLED uses organic light-emitting materials and is a different emissive technology.

• Direct-view LED, the subject of this guide, forms the visible image from inorganic light-emitting diodes at the display surface.

1.5 Strengths and constraints

The principal strengths of direct-view LED are scalability, high luminance, modularity, freedom of aspect ratio and the absence of bezel lines. It can serve close-viewed indoor work, outdoor daylight applications, large venues and creative installations.

Its constraints are equally important. Fine pixel pitches can be expensive and demanding to manufacture. The display needs control, processing, power distribution, supporting structure and suitable content. Image quality can vary with viewing angle and ambient light. Close viewing can reveal pixel structure or surface texture. Large, high-brightness canvases can require substantial electrical and thermal planning. A correct decision therefore depends on the application rather than a general claim that one display technology is always best.