While the trends point to a solid-state future for projectors, don’t count traditional lamped-based projectors out. Regardless of whether it’s for a classroom, lecture hall or a university’s large auditorium, the differences between solid-state and traditional lamp-based projectors presents the college buyer with a series of pros and cons. Although they look alike on the outside, under the surface these two types of projectors couldn’t be more different.
Traditional projectors work by heating a thin filament with electricity in an inert gas atmosphere inside a bulb to produce the full spectrum of light, from red to violet. Because its light is emitted in a spherical pattern, a conventional projector needs a bulky reflector to catch and concentrate the light.
Whether it has LEDs or lasers at its heart, a solid-state lighting element differs by delivering specific red, blue and green wavelengths. This not only eliminates the projector’s reflector, but the light can be aimed directly at the DLP, LCOS or LCD imaging array. It also allows the projector’s color balance and temperature to be minutely tuned via software.
The problem is that while there are many powerful blue and red laser designs, green is not an easy color of light for a laser to produce. The answer is to start with a blue laser that shines onto a phosphor-coated disc that converts its beam to green, yellow or white light. From there it’s aimed at the imaging target.
There’s one thing that lamped projectors can’t match: vertical operation. It depends on the actual model, but many LED and laser projectors let you aim the lens straight up or down without worrying about the device overheating. This allows them to be used as digital scenery in the college’s theater as well as in an art or dance project.
Although solid-state projectors continue to come down in price, lamp-based projectors still cost about 30-percent less. That lower upfront investment is tantalizing for buyers looking after an institution’s bottom line. However, it’s balanced by the traditional projector’s need for a new lamp every 2,000 to 3,000 hours of use. Over 10-years of typical college use, this might add up to five or more lamps at a potential cost of several thousand dollars, not to mention the downtime, hassle and cost of changing the lamp.
By contrast, the lighting element of a solid-state projector is rated to last for 20,000 to 30,000 hours. Even at 10 hours a day of use in a classroom, lecture hall or auditorium, during the academic school year, it adds up to 10 or 15 years of daily use. This not only eliminates the annoyance of a professor getting to a class only to find that the projector is burned out, but shows up in lower operating costs with electricity and filters (if they’re needed) as the only recurring expenses.
The only true way to decide between these projector genres is to run the numbers. Texas Instruments has an online interactive Total Cost of Ownership (TCO) calculator that can estimate the complete costs of each projector based on your institution’s needs. Just enter how many projectors you need, how often they’ll run and other operational details, and the online calculator will estimate each’s costs over its lifetime. In other words, it provides a level landscape for comparing projectors.
For uses that don’t require a lot of projector time, inexpensive traditional projectors may make more sense because the lamp will last many years. On the other hand, the more you use a solid-state projector, the cheaper it gets, so this genre takes the lead in high-use scenarios. If you do your homework, every school location will get exactly the right projector for the teaching task at hand.