There is still a knowledge gap in LED technology, we therefore hope that the information below is helpful.
Quality White Lighting
Quality, when used to describe white light from LEDs, refers to the consistence of colour in the beam of light. This is achieved with advanced packaging, materials and binning coupled with phosphor expertise and technology. The light colour will settle (degrade) over a period.
A key element in delivering quality high-power LEDs is managing the heat emitted from the LED chip. If managed well it allows for increased light output performance. A good thermal heat sink extracts heat from the LED chip. If not managed well there will be a reduction in life expectancy, reduced lumen output and changes in colour output of the LED. A 11̊C rise can reduce the LEDs life span by 50%!
Lumen maintenance is a measure of LED reliability and is simply the amount of light emitted from a source at any given time relative to the light output when the source was first measured. This is usually expressed as a percentage. When changing a light bulb you notice how bright the new bulb is compared with the older bulb, you are seeing the effects of lumen depreciation. This steady decline over time is known as lumen maintenance. The material inside the bulb will continue to deteriorate until finally the bulb will no longer emit any light. A conventional light source will usually fail before our eyes.
LEDs also experience lumen depreciation but it happens over a much longer period of time, usually tens of thousands of hours. An LED is a complex package of materials that must all work together to deliver long lifetimes. Everything from the design of the chip, thermal management, optics material, phosphors and even the assembly of the entire package will affect lumen maintenance.
LED chips are easily damaged by excess current, if passed through an LED the chip temperature increases and either the chip is destroyed or the lifetime of the chip decreases.