Light Diffusion & Poster Light Box Technology
Posted on 25, February, 2015
Last Modified on 19, March, 2015
Edge-lit light boxes on the market today use several types of bulbs (CCFL, LED T5), however, without a tested and developed light diffusion method any bulb is worthless. Read on to discover the types of diffusion patterns and understand how they affect your light box's performance.
What is Light Diffusion?
Light diffusion is a method that transmits the brightest light found near the edges (near the bulbs) to areas of the light box that have the least amount of light (the center of the panel). This way an even pattern of distribution (all areas of the panel are the same) is achieved. Alternative patterns - those preferred by us - transmit slightly more light to the center of the panel, which is the central focus point for viewing graphics, and slightly less light to the perimeter, or edges, of the panel. Transmiting more light to the center of the panel and less to the perimeter is technically more difficult than to distribute light in an even pattern. But again, this is the method preferred by us. The whole concept of diffusing light away from the light source (lamps) resolves the traditional light box issue of having "hot" and "cold" spots or "shadows" on the graphics.
There are three basic methods of diffusing light from the bulbs, and within each technique there is a lot variation. To date, the three methods of diffusing light are printed patterns, CNC engraving, and most recently, a light diffusing acrylic. Our tests have generated qualified printed and CNC patterns that can transmit enough LUX (brightness) to meet our standards, but almost all homogenous acrylic methods have, so far, failed our LUX standards.
A truly high-quality light box has an efficient diffusion pattern giving either:
- Even glow throughout the panel
- Transmission of more light to the center of the panel
How To Spot A Fake Diffusion Method
A light box purchaser needs to be aware of many fake manufacturers, or manufacturers making false claims about how their light boxes are "homogenous" and utilize diffusion patterns (see the comparison images). Many of these manufacturers take short cuts to avoid existing patents, so they end up printing or engraving a pattern in the acrylic panel that has no logic to it. Their patterns do nothing to transmit or diffuse the light effectively. It is just a grid or pattern put on the acrylic to fool the consumer into thinking it is a technically advanced light box. We have seen countless samples where there is a straight grid pattern (which is akin to no pattern) imprinted in the acrylic. When we see these substandard patterns, we say to ourselves "what are these guys thinking?" or "what is the purpose of this pattern?" A true light diffusion pattern will not be "uniform", but an irregular pattern calculated by algorithms that takes into consideration the area of the panel, the distance between lamps, the thickness of the acrylic, and the wattage of the lamps. Most of these algorithms and techniques are patented.
Examples of Good & Bad Light Diffusing Patterns
Correct Light Diffusing Patterns: A printed diffusion pattern is spaced further out at the edges (closest to the bulbs) and is tighter at the center where more surface area needs the illumination.
Fake Light Diffusing Patterns that do not adequately distribute illumination because the squares are evenly spaced out throughout the entire pattern.
There is a delicate balance when plotting out the pattern so that neither hot or cold spots are created. When sourcing and designing our light boxes, we measure the light intensity with a LUX meter. We tested several light boxes using very stringent standards, and the light boxes that we have chosen offer amazing brightness levels as well as an even disbursement of the light. Beware of vendors selling imitation patterns. Our products are the real deal, and we are sure you'll be happy with their performance!