GCN Lab: DLPs show longevity in test

GCN Lab: DLPs show longevity in test

Texas Instruments Inc., the company that invented digital light processing, wants to prove that DLP projectors surpass rival LCDs in length of service.

The company sponsored a longevity study by the Rochester Institute of Technology in New York, pitting five LCD projectors against two DLPs. The RIT researchers kept them all running continuously for 4,000 hours, checking at intervals for luminance, contrast and chromaticity. A projector was failed when it showed uncorrectable flaws in the test image.

According to TI, organizations tend to use digital projectors about 1,000 hours a year, so the 4,000-hour test would indicate expected longevity up to about four years.

The projectors did need new bulbs during the study, but the researchers were looking not at bulb life but rather at degradation of picture quality, which a new bulb cannot fix.

In all cases, the RIT researchers said, LCD projectors began to show problems after several thousand hours of use. First the blue filter would begin to fade, which means that blue light was not being stopped and would bleed into images that were supposed to be black. Then a yellow tint would appear over the images.

Although two LCDs were still performing well after 3,456 hours, none survived the entire test without serious image flaws.

The two DLP projectors, which do not pass light continuously through a filter as LCDs do, had the same image quality at the end of the test as when it began.

Texas Instruments representatives visited the GCN Lab this week with two of the projectors that had been in the study. The image from the DLP projector looked better than the LCD's image, which was yellowed and washed out. TI also brought components from some of the failed LCD projectors to show where filters had burned away.

Company officials said they hope the results of the study will help government agencies justify the generally higher cost of DLP projectors on the grounds that they need replacing less often.

About the Author

John Breeden II is a freelance technology writer for GCN.

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