Every projector ever made needs to have a lights source, this is for obvious reasons as it is a machine that must project a bright light. These light sources have changed over time starting out as low wattage incandescent bulbs to High-Powered LEDs which are more common now.
Up until recently the most common type of light source used in projectors were high pressure mercury bulbs, these are still used in some full-sized projectors today. Initially these bulbs had a high cost and had to be changed about every 4,000 hours of use. To make things worst as a side effect of the bulb going bad it gradually gets dimmer throughout it’s life. Normally this dimming effect is so gradual that many users don’t even notice it until they change the bulb and figure out they’ve been watching at 50% brightness. So for the average user that wants their projector to be looking as bright as possible at all times, they are looking at replacing the bulb at half it’s lifespan (around 2,000 hours) and for a $200 bulb that can get expensive. Not to mention the mercury bulbs aren’t very good for the environment, many of them end up in landfills and since they contain mercury any leakage into the soil is a pretty bad thing.
So along comes LEDs. As we saw with TV’s and the move from LCD to LED technology, the little plastic bulbs that used to be mainly used in rave lights are making a move into higher technology. Some projectors have started to employ LED optical engines into their projectors. The first projectors to use this newer LED technology were Picos, this is because picos are too small to have a replaceable bulb in the first place and since the LED optical engines can be very small and have a long lifespan (up to 25,000 hours) they can be integrated directly into the projector. There was a lot of static at first regarding the fact that you can’t change the bulb and for people that have been using conventional projectors for a long time probably don’t really believe in the longevity that the LEDs claim to have. However if you have a 25,000 hour bulb and you run it for 4 hours a day, thats about 14 years of use. When you factor in the cost of replacement bulbs on a conventional unit the cost will far surpass just replacing the LED unit once it burns out. The LEDs also have better color and pixel density than a pressure lamp creating a very crisp picture.
So whats the problem, if LED’s are so much better why aren’t all projectors using them? Well, the answer to that question is that LED optical engines just are not at a point where they are bright enough to compete with the pressure lamps. Even some of the higher-end LED projectors are about 1000 lumens while pressure lamps can go all the way up to 10,000 lumens. The difference is big here but the technology for the LEDs is constantly improving, just a few years ago they were capable of about 100 lumens and since then it has gotten 10x better. What this boils down to is, if you’re presenting to hundreds of people in a lecture hall or have a private movie theater in your house then a pressure lamp may be the way to go. If you are just going to be watching shows with your buddies or using the projector for personal use then LED is the way to go in almost every way.