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Casio LED/Laser Hybrid Update

We are still waiting for a statement from Casio regarding the brightness issues we've seen on the new LED/Laser Hybrid light engines. But in the meantime, we have some more test results to share...

Since we have had a total of five units in house, we've been able to do some extended usage testing to see if the Hybrid light engine maintains its brightness and color characteristics over time. Our findings thus far are that maximum lumen output drops over the first 100 hours of use. On one of our XJ-A130s, the max lumen output was 1228 when it was new. After 130 hours of use its maximum brightness dropped to 949 lumens, which is a 23% reduction.

The Casio User's manual indicates that the high altitude mode of operation (which increases fan speed and audible noise) is recommended at elevations above 3300 feet. We do our testing at 3100 feet. Since this is close to the limit, we decided run a second test with the high altitude fan engaged. The second unit started with a maximum reading of 1630 lumens, and after 100 hours of run time its maximum lumen output had dropped to 1470, or a 10% drop.

Two notes of caution are in order. First, in order to get 100+ hours of use on these test units, they were run with a 100 IRE white test pattern continuously, 24 hours per day. This is not the way people normally use products of this type. We do not know whether brightness degradation is exaggerated by continuous use. More testing of a wider array of samples under different usage conditions would be required to support any definitive conclusions.

Second, we do not know the degree to which our 3100 foot elevation is affecting results. It may be that brightness degradation would proceed at a slower pace at sea level. Though the test unit with the high altitude fan engaged has diminished less over the first 100 hours of use, this was a much brighter unit to begin with. Furthermore, it draws 178 watts in full power operation, whereas the dimmer test sample draws only 138 watts. There are too many variables, and not enough test data, to draw any certain conclusions.

We have noticed another interesting phenomenon as a result of the extended usage test. Color balance on the first of the two units (the one which now measures 949 lumens) actually improved after 130 hours of use. Initially the picture had excessive blue and green components with very little red. Now it looks more neutral, with red coming more into balance with green and blue. It appears that the red component, which comes from the LED, remains relatively stable in its light output, while the blue and green that are produced by the laser diminish over time, causing the unit to trend toward a more neutral color balance.

So far we have seen this on just the dimmer of the two test samples. The brighter of the two units still shows a significant weakness in red, and color balance on this sample is quite poor.

We will continue to run these units to see what further developments ensue. And we will report any information forwarded to us by Casio once they have had a chance to evaluate the issues at hand.

Evan Powell

Comments (8) Post a Comment
kevinp Posted Jun 6, 2010 4:27 AM PST
I like the idea of using green tech. but am confused as to why Casio didn't use a green LED with red & blue lasers. I am wondering if it has anything to do with speckle. Is there any speckle produced by the blue laser ?
chris Posted Jun 7, 2010 11:23 AM PST
I'm excited that you are testing more LED projection systems. However, have you ever done the lumens times test on mercury vapor lamps? What does the brightness curve look like for the most highly rated units you've tested this year?
Evan Powell Posted Jun 7, 2010 12:51 PM PST
Kevin, I presume the reason they did not use LED for the green channel was that it is not bright enough. The objective of the laser was to boost light output. Not using it for the green channel would have largely negated the design strategy.

Chris, the tendency for high pressure lamps to degrade in brightness over time is well known, so we have not tested that recently. The reason we are running the tests on these new hybrid engines is that they are represented as being stable and not subject to lumen degradation. If this were true, it would be a competitive advantage over high pressure lamps. However, our initial tests indicate that they do degrade in brightness over time. We do not have enough test data to form any conclusions about whether they degrade faster than conventional high pressure lamps, or how they might compare to brightness curves of UHPs after thousands of hours of use.
Nick Chi Posted Jun 8, 2010 2:27 AM PST
Thanks for the tests, guys!

However, i am wondering that using this projector on a high altitude level at 3100 ft. will cause some over-heat problem for the 'lamp' (I mean LED and LD array of course ). I think the air pressure is somehow rare at that elevation, and it cannot cool down the 'lamp' efficiently, that is why the mode for "high altitude" increases rpm of the fan, and make louder noise. Therefore, I do not have big concern on the lifetime of the 'lamp' when you do not leave it on 24x7 and in a low elevation.
Evan Powell Posted Jun 8, 2010 7:04 AM PST
Nick, I share some of your concerns. Running a test 24/7 is not a normal usage environment, and we do not know the degree to which 24/7 operation affects results. However, 3100 feet is not all that high. Most projectors do not need high altitude fans until they get to 5000 feet or higher. Our latest measurement shows that the A130 we've been running with the high altitude fan on has lost 25% of its brightness in 200 hours. That fan should compensate for any rare air here in Vegas.

At this point, we know that the light source will degrade over time. The big unknowns at this point are (a) whether 24/7 operation exaggerates the rate of lumen degradation, and (b) whether the light source will stabilize at some point and not continue to diminish with further usage. For those planning heavy duty cycles on this 20,000 hour light engine, these would be good things to know.
Alan G Posted Sep 3, 2010 12:28 PM PST
As to the use of a laserversus an LED, Casio states that it produces the component colors in the following way: "Red by red LED, Blue by a blue laser and Green converted by phosphor from a blue laser. This source achieves high luminance over 2000 ANSI lumens safely by employing a phosphor device to modify the wavelengths and phases of blue laser light through DLP® system."

Essentially, There are no green LEDs or lasers bright enough for projection right now, so the blue laser is used to cause a phosphor to emit the desired wavelength and intensity. The laser excites the phosphor, which emits light in response.

The likely reasons for the improvement in the strength of the reds is twofold. First, the phosphor is likely degrading over time through continuous use (as all phosphors do). Second, blue lasers tend to be short-lived versus other wavelengths, and do indeed degrade over time.

IMHO, I just don't think this approach is ready for primetime. Until we can find LED and laser diode construction methods that yield increased brightness and longevity for these problem wavelengths, we won't see a viable solution for LED/LD projector engines.

Cosidering all the hype over the last two years over the possibility of LED-based projection technology, it's telling that there is really nothing on the market that is really living up to the hype. You have to assume the manufacturers are having a really hard time coming up with something that really works and has a reasonable MTBF.
Eric Posted Oct 3, 2011 7:22 AM PST
This is a great discussion. I'm glad I came across this thread. I work for a school district and we are considering a switch to LED projectors to save on lamp replacement costs. So far I have read reviews similar in nature to your findings.

Is there a way that your testing facility could test these projectors in a more lifelike scenario? In the classroom for example, they have the potential to be turned on and off 5 times or more per 8 hour day. Additionally, they handle multiple source content (ie movies, presentations, etc) I read that you use the white test pattern continuously 24/7. I think that is good from a high usage perspective. How is the brightness affected by on/off cycles and 'real' content, if at all?

I guess the bottom line is, do we jump on board with LEDs? From what I have been reading, the opinion is pretty split.
mike Posted Oct 18, 2011 11:40 AM PST
I work in a museum, and we've been using the Casio XJ-A240 for recent exhibitions. The units are running 8 hours a day, six days a week. We have noticed significant color changes after a few months of this kind of use. Whites turn a bright yellow. We are considering going back to units with conventional lamps. Any thoughts?

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