This relates to the bulb (lamp) that is used to project an image and is measured in hours. Basically the more hours the better as lamps are not cheap to replace. If you watched two hours a night on your projector with an a lamp life of 3,000 hours it would last around 4 years. By this time you may be looking at getting a new projector anyway.
This refers to the "half-life" of the lamp inside the projector. This is the point where the lamp is half as bright as it was when it was first being used. It will gradually lose brightness with use, and it is recommended to replace your lamp when it exceeds it's lamp life.
The median life span of a very large number of lamps (also known as the average rated life). Half of the lamps in a sample are likely to fail before the rated lamp life, and half are likely to survive beyond the rated lamp life. For discharge light sources, such as fluorescent and HID lamps, lamp life depends on the number of starts and the duration of the operating cycle each time the lamp is started.
A measure of lamp performance, as measured in median hours of burning time under ANSI test conditions.
Usually the time in hours in which 50% of a large Batch of Lamps can be expected to survive. It is based on Laboratory conditions that do not prevail in practise, so it can only be taken as a guide.
The average rated life of a bulb or lamp. Usually the lamp life is printed on the package.
Rated life of a lamp, as established through laboratory testing during which a sample group of lamps is burned, including being subjected to a scheduled number of starts per day. The length of time required for half the lamps to fail is the rated lamp life.
The average rated life of a lamp refers to the point where 50% of a test batch of lamps are still operating. Some of the most common lamps used in office task lighting have the following average rated lamp life: Incandescent 750-1,000 hrs. Halogen 2,000 hrs. Compact Fluorescent 10,000 - 12,000 hrs.
The life of the lamp that is in your television. This particularly applies to CRT direct-view televisions, CRT rear-projection televisions, projectors and DLP rear-projection televisions. There is no such ‘lampâ€(tm) in LCD and Plasma televisions.