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Pushing the Video Projection Envelope

From Gas Lamps to Solid State

Achieving the highest levels of video projection– with thekind of image uniformity that enables sophisticated edge-blendingand pixel mapping– is still very much the domainof the Xenon lamp-based projector. At Palmaz Vineyards inNapa, California where winemaking and aging takes placewithin the living rock of Mount George, Vista Systems’ Spyderplays a key role in the advanced technology Palmaz uses to aidwinemakers in creating complex, elegant, super premium wine.The cave’s fermentation dome is the world’s largest reinforcedunderground structure with dimensions spanning 72 feetin diameter and 54 feet high. Twenty-four fermentationtanks rotate on a massive custom-designed carousel.Temperature stays constant at 60 degrees and humidity at75 percent, the perfect atmosphere for aging wine. Palmazpartnered with Acrolon Technologies and aerospace metalfabricator Rodney Smith to create the first fully algorithm-basedfermentation control system featuring proprietaryintelligent instrumentation in each tank which image morethan 10 million points of temperature inside the tank space,providing the winemaker a live visual thermal representationof the tank. To gain a full understanding of the state of eachtank, however, the winemakers need to constantly reviewthe tank data. How to put the data in front of them? An iPadaccompanies the process but referencing 30 days worth ofdata across 36 fermenters on a 9.7” screen can be cumbersome.Positioning the data so that critical information could beobserved without having to search for it became the goal. Thesolution was large scale projection with Christie’s HD14K-Mprojectors– whose Xenon lamps afford the kind of imageregularity that enable geometric correction at an unbelievablelevel and focal depth lengths never seen before. The VistaSystems’ Spyder X20 1608 creates a pixel cloud of unparalleledsize. The system includes a simple custom app for Apple iPhoneor iPad that allows the winemaker to trigger projectionssourced by a Mac Pro tower running a sedna Presenter and fedto the six Christie projectors, which perform the warping forthe dome, and the Spyder, which handles the edge blending.

The one requirement in the world of AV relative to display technologies is the need for illumination– a source of light at the projector or display. For those of us who are technical junkies it boils down to the properties of the light as noted in the electromagnetic spectrum and the CIE Color Chart. In the world of AV this concept gets reduced to a more succinct reference of RGB or red, green, and blue– that when additively combined create of white light. It is not an overstatement to say that the quest for “pure white light” is the holy grail of display technologies going back to the very beginning.

From the earliest days of film projectors, a bright white light was transmitted through the film stock and then to a lens focused onto the screen, hence the term transmissive technology. Fast forward to modern LCD displays and they are also transmissive in nature where the light source is transmitted through the layers on the chip or panel and in the case of a flat panel display onto the screen surface or in the case of digital projectors, through a series of optics and an exit lens onto the screen.

All does not reside in the realm of transmissive illumination though. Both DLP and LCoS are reflective projection technologies and the light source or illumination is reflected off of the chips and through a group of optics and then toward an exit lens and onto the screen. The common denominator in all of this from film to digital displays is the need for an illumination source.

As in all things, the only constant is change and so it is in how we produce light for displays. From this perspective it began with a basic lamp as a light source. All sorts of advances have taken place from the early incandescent lamps to our current UHP (ultra-high pressure) mercury vapor lamps which are actually a distant relative of the mercury vapor lamps used in street lights. There is also a second type of lamp in use, on very high end, and extremely bright projectors, and these work differently. They are Xenon lamps. Overall, they can produce a better color range than the UHP type lamps, and use xenon, not mercury as the inert gas in the lamp envelope. These Xenon lamps tend to be significantly more expensive, and have a shorter life than most UHP lamps. They tend to start at over $1000 each, and typically have a lamp life of 500 to 1500 hours compared to UHP lamps good for 1500 to 5000 hours and costing less than $500 each in most cases.

Although they are tried and true and a known quantity, the Achilles heel of current projection lamps is twofold. There is the need to change lamps regularly as they decay in light output degrading the image onscreen and the viewing experience but also facilitating a negative shift in color accuracy and saturation. As noted before we have lamp life to consider and we not only have the expense of the lamp but the cost of labor to change out the lamp. This plays directly into the TCO or total cost of ownership of a technology and with flat displays panels increasing in size and not requiring frequent lamp replacements, this has put a burden on the projection industry to come up with a solution. Necessity being the mother of invention we enter into the newest realm of illumination, LEDs, hybrid illumination sources, and RGB laser light sources.

Light Emitting Diodes (LED) seem to be everywhere and have been used for some time now in projection but mostly in tiny Pico projectors. The advantages to LED illumination is simplicity, energy efficiency, and they last a long time compared to traditional lamps. The problem with LEDs is that brightness typically tops out at under 1000 lumens creating a hurdle that has yet to be overcome.

Once again necessity comes into play and the folks at Casio were the first to introduce what they call the Casio Hybrid LED-Laser Light Source Projectors taking us to the next level of brightness in the 2k to 4k ranges of brightness in very compact designs. These use a combination of LEDs and lasers for the red and blue light channels and since green lasers are expensive and green LEDs are not bright enough, they use a rotating phosphor disk to create green. Although Casio was the first to work in this hybrid venue, they are by no means the last. Here are three different approaches to alternative means of illumination from the top down starting with Digital Projections Inc. and their approach.

Mike Levi the President of DPI continues to be a wealth of information on all things dealing with projection so this seemed a logical place to start. He is very bullish on advances in laser-hybrid illumination technologies. He noted that “Digital Projection now offers 2 distinct 3-chip DLP LASER-Hybrid illumination projectors. They utilize banks of blue lasers as the illumination and stimulation source. Some of those blue lasers are focused on a phosphor wheel which produces yellow light, which is then split to the red and green light that illuminates the red and green DMD’s. The remaining blue lasers go through diffusion and integration and provide direct illumination to the blue DMD. Although initiated by lasers, the light that exits the lens is no longer structured, as laser light is, and thus does not exhibit any of the negative characteristics of pure laser, such as speckle. We have worked hard to define the X and Y coordinates of the yellow phosphor and the blue lasers to attain an optimum color space. Indeed, our 3-Chip LASER-Hybrid products produce a color space that matches/ exceeds REC 709.”

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Pushing the Video Projection Envelope

Dec 3, 2014 4:30 PM, By Alan C. Brawn

From Gas Lamps to Solid State

Goran Stojmenovik, Product Manager for Solid StateIllumination for Barco, says that Barco’s strategy for fullyexploiting the benefits of solid state illumination is to begin atthe top light output of 60K for digital cinema and then workdown to the lower lumen light outputs.

Mike went on to point out “the useful life of 20,000 hours with linear lumen maintenance performance to 50% (of original brightness) at 20,000 hours. To put this in perspective, this means that at 2,000 hours, our LASER-Hybrid projector is still 95% as bright as it was when it was brand new, and at 10,000 hours, it still retains 75% of its initial brightness.” He also notes that for 24/7 venues, their laser illumination engine is replaceable, so customers who might actually attain 20,000 hours of use can simply order a new laser illumination module, thereby restoring the projector to its initial performance and retaining the benefit of their investment in the projector. They put their money where their mouth is in terms of warranty protection and they provide 3 years of coverage on these models inclusive of the illumination system, with no limitation on the number of hours accumulated. Obviously they get the concept of TCO!

Some people are under the misimpression that laser hybrid illumination only works with DLP reflective technologies and this is just not so. Some years back when Samsung was in the projection “game”, they introduced a 3 chip LCD projector with LED illumination proving that non-traditional illumination would work in a 3 chip configuration. Fast forward to current times and the folks at Sony have their BrightEra 3 chip LCD technology and a pure laser light source through a phosphor wheel to create white light. The light then passes through a series of dichroic filters to produce the red, blue, and green needed to create the full color images on screen. Like other laser-hybrid technologies they achieve 20,000 hours of life with superb colorimetry and contrast and a stable image throughout the life of the illumination source.

The latest advancement that we are seeing in illumination is in true solid state illumination. Full Laser projectors are starting to appear in the digital cinema market as noted in an earlier article by our editor David Keene. By using three separate lasers—red, green and blue— outstanding color is possible. However, the cost of the green laser will limit the availability of pure laser projectors for several years

Our last example of new illumination sources resides in the hands of Barco. We spoke to Goran Stojmenovik who is the Product Manager for Solid State Illumination for Barco. He began by stating that “Barco is a broad line projection company and has products for applications requiring under 5K of illumination all the way up to digital cinema requiring up to 60K illumination.” For their work in solid state illumination he noted that “the strategy at Barco is to begin at the top light output of 60K for digital cinema and then work down to the lower lumen light outputs. The philosophy at Barco is not necessarily to be first but to be the best in terms of image performance and this carries over to solid state illumination”. Goran says very simply that “we want to get it right”. He spoke of three segments that he sees in the quest for the development of laser and laser phosphor based projectors. “From a cost/performance perspective there is the blue laser with phosphor wheel to produce white light and that is applicable for up to about 10K lumens at the current time. At the other extreme there is the 30K to 60K projector that use the full RGB laser array. This leaves the “sweet spot” of 12K to 25K to be developed further.” According to Goran the current hybrid using blue laser and phosphor is not yet in that “sweet spot” and the full RGB lasers are too expensive for this market niche. Goran points out the significance and market demand in this range of illumination and teases that Barco will address this sooner than later and when they do they will “get it right”.

For those of you who are familiar with some of the regulations surrounding lasers it was safe to assume that this might have limited their development as an illumination source for projectors. Pete Ludé, the current president of LIPA (Laser Illuminated Projection Association), gave an update last spring on the regulatory issues for laser projectors. He pointed out that over the past few years the industry has been waiting to see if FDA regulations about use of laser devices were going to hold back the technology. He said that “this has not been a deal-breaker for high lumen laser projectors as its possible today to get a situational variance with a bit of paperwork from the FDA to install a projector, but it’s been a speed bump.” Ludé explained that on March 16th, 201

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