At the Wales Millennium Centre in Cardiff, Wales, the ticket counter’s 52ft-wide back projection display uses DLP projectors rated for 24-hour operation, and is fitted with UHP lamps to ensure reasonable running costs.
and is fitted with UHP lamps to ensure
Many display applications, such as lobby displays, permanent exhibits, digital signage, and control rooms, require 24-hour operation. There are many products (especially projectors) that are simply not up to this work — although they may be absolutely fine for use in training rooms or occasionally used corporate facilities.
There are two issues in cost of ownership: the longevity of the display itself and the cost of consumables such as projector lamps and backlights. Budget-conscious museum directors are understandably upset when they find the LCD projectors need replacing after three years because of panel failure, and apoplectic when they face lamp bills for hundreds or thousands of dollars a month.
Thus users and systems integrators need to face up to the cost of ownership issues from the outset. Projectors designed for 24-hour use will have a higher initial cost, but will pay for themselves very quickly. It is dangerous to generalize, since progress can quickly invalidate received opinion. However, the current situation with regard to heavy-duty projection is that LCD is not ideal for this work. The jury is out on LCoS because there is simply not enough track records to form an opinion. DLP is currently the best option.
As far as lamps are concerned, designers will often do better to base displays on smaller images requiring lamps in the 100W to 200W range, where they can use projectors based on UHP lamp technology (or its equivalent from other manufacturers) where rated lives of 2000 hours to 8000 hours are the norm. (But beware of weasel words. Rated life in this field is the time taken either for a lamp to drop to half its rated output or for a given large quantity of lamps to have suffered 50 percent failure — so practical lamp life is less.) For big projectors, it is best to go for projectors with cinema-style lamp houses, since these can use lower-cost conventional xenon lamps.
Robert Simpson, founding director of the Electrosonic Group, has spent nearly 45 years in the AV business. He is a member of SMPTE, SID, and SPIE, and holds the ICIA Distinguished Achievement Award.