Count Jim Hirsch among the supporters of DLP technology. Hirsch, the chief information officer for the Plano Independent School District in Texas, estimates his district has saved between $700 and $1,000 per unit over the lifetime of the machines by purchasing DLP projectors.

"We began our large-scale installation of DLP projectors in the summer of 2001," he said. "Prior to that time, we had approximately 200 LCD projectors in use across the district, and we were experiencing a life expectancy of about three years before the color shifting got to a point where their usability was questionable."

Hirsch added: "We currently have 1,944 DLP projectors installed district-wide. During this time, we have replaced a total of five DLP projectors and have had almost no issues with image quality–[though] I can’t comment as to whether the life expectancy of usable color from LCD projectors has improved since we stopped purchasing them once DLP became our standard."

Plano has purchased several DLP models from PLUS Vision Corp. and has been happy with the results.

"As for estimated cost savings and/or avoidance, it’s a pretty simple formula from our way of thinking," he said. "During our initial purchases, there was a slight cost premium for DLP–between $100 and $200 per unit. That cost differential has since disappeared.  The major cost savings have been in projector maintenance."

He explained: "Simply considering typical usage of around 20 hours per week for 40 weeks each year provides 800 hours of use each year. With the typical filter cleaning needed on LCD projectors at each 200 hours of use (actually, the recommendation might even be 100 hours of use), that would be four cleanings per projector each year, at a cost of $30 per cleaning–or $120 per projector each year. The math at this point is pretty straightforward, multiplying the expected number of years by $120."

This calculation doesn’t include possible replacement costs that could result from the faster degradation of image quality in LCD projectors, Hirsch said.

"Although we fully expect to see eight to 10 years of usage from our DLP projectors–and we’re on track based on replacement statistics so far–I really didn’t take into account that we might have had to totally replace LCD projectors at least once during that same time span," he said.

A study commissioned by Texas Instruments and published in 2006 by independent testing firm Intertek found that the LCD projectors tested showed varying degrees of color decay after 2,000 to 3,000 hours of continual use. No such color decay was observed in the DLP projectors that were tested.

–D.P.

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