Reader Al Mercer wants to know more about bulbs for television sets based on digital light processor (DLP) technology:
I enjoyed your recent article on HDTV in the Mar. 6 issue of BusinessWeek. I would like to learn more about the lamp life of large DLP projection TVs. I want to buy a 62-in. projection TV, but I have heard that you have to replace a very expensive bulb every two years. I have a friend whose bulb had to be replaced after one year.
Your friend either had very bad luck or watches an extraordinary amount of TV. The lamps in rear-projection TVs are typically rated at 6,000 to 8,000 hours and cost between $200 and $500. The reason? The systems are designed in such a way that the bulb has to be positioned correctly to within a fraction of a millimeter.
A secondary problem: You'll damage the bulb if you touch it with your bare hands. For these reasons, you have to change an entire lamp module rather than just a bulb.
SIMPLER DESIGNS? Since this module includes a significant chunk of the optical system, replacement lamps can add up to a significant cost over the life of a projection TV. But they still have an advantage in price. The difference between, say, a 60-in. plasma screen and a 60-in. DLP projection set is so great that you can buy all the bulbs you need to make the projection set last as long as the 60,000 hour-rated life of the plasma -- and still have money left.
Still, there's general agreement that projection bulbs are too expensive. Part of the reason for the high cost is the fragmentation of the consumer-electronics industry. Bulbs are assembled according to dozens of different designs, all produced in relatively low volumes, keeping costs high. Texas Instruments (TXN), which makes the DLP chips used in many sets, is leading an effort to encourage the use of simpler, common lamp designs across brands and reduce the cost of replacements. But given the go-it-alone attitude of many manufacturers, success is far from assured.