Here are Christie's lamps:
http://www.christieinc.com/xenolite.htm

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John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Eastman Kodak Company
Research Labs, Building 69, Room 7419
Rochester, New York, 14650-1922 USA
Tel: 716-477-5325 Cell: 716-781-4036 Fax: 716-722-7243
E-Mail: john.pytlak@kodak.com

Beven tells me the new "magic lamp", the CXL-60 is all new and has everything one wants without the heat...the only pain is that it is only available in an HTP package.

BEven hinted that Strong was looking into making an adapter for the Ultra-80....anything to this Pat?

Steve

Might be worth a discussion here. Who has experience with these types of higher output lamps?

I understand these lamps have a shorter arc gap and/or higher gas pressure -- that's what makes them "brighter". However, the downside is the arc "burns back" the cathode that much faster, so the light output degrades at an increased rate.

The current digital projector manufacturers (using DLP technology) like the smaller arc space, as that characteristic increases the efficiency of the system's light output. They also struggle with the increased arc space and deformed plasma ball as the bulb ages.

When you say experience with these high-output lamps, what do you mean?

Just lamps over the traditional 4KW or the new generation of lamps like the CXL-60 (or even the OSRAM XBO 5000HS)?

I have used the traditional 7000HS lamps that have been used for some time now (ORCs mostly but Christie and Osram have their offerings too). The OSRAM 5000HS is a relatively new offering and uses a very large cathode pin (where as most manufacturers have kept with the small 2500HS pin throughout the 2500-7000 watt range).

I'm looking to try out the CXL-60 and hope that there will be a CXL-60SC someday. To hear Beven speak of it...it is just magical, more light than a 7KW, less heat, longer life...able to leap tall buildings on a single drop....

Steve

It's pretty well agreed that (in general) light output is proportional to operating current. If a 7kw bulb is rated for 170A and a 4kw bulb is at 140A, that's only about a 21% increase in current (and light) from my experience. The big increase is in power (4000 vs. 7000), a 75% increase in energy. Most of that increase has to be in other energy, such as radiant heat, UV and IR, etc., and not just visible light that we want on screen.

What the newer designs seem to feature is a relatively higher operating current with a smaller arc gap, reducing the arc voltage. New 6kw designs probably run around the same amperage as a 7kw but with a smaller arc space -- hence a lower arc voltage -- hence the lower power rating with about the same (or better?) light output, less heat and energy, etc.

The question I have is long term operation. As the bulb ages, the cathode tip and anode degrade ("cathode burn-back"). As this happens the arc space increases, and so does the voltage across the arc. The plasma ball that produces >80% of the light from the lamp is also larger and more poorly defined, so it's not collected as well by the reflector.

So assuming the same operating current, the lamp will require more power as the bulb ages, since the arc gap (and arc voltage) increases. That sound logical?

I also don't yet have a feel for how the light output might change over time. That would be some interesting data to see.

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Remember that the bulb alone is responsible for the voltage across the arc, and that's a function of arc gap, fill pressure and temeprature. The power supply only controls power and since the bulb controls the voltage, the change in power is seen as changes in current.

At 155A, 7000W of power means an arc voltage of about 45VDC. Is that what you get with a voltmeter across the arc?

The Switchers have a Coarse and a Fine control. It could well be the coarse control is set to limit output at that setting, maybe a full 4000W output. That control is down inside the switcher as I remember. I don't remember the full current output of the 7kw Switcher but it should be around 160A or so -- check the data plate to be sure.

Note that our Switchers are current-regulated, meaning that the system monitors only current output and not the voltage for regulation. That might mean this situation: a new bulb is installed and run at 140A, 30VDC on the arc (4200 watts). As the bulb ages, the arc voltage will tend to increase as the gap increases. Say it goes up to 31VDC, and the switcher is still going to run 140A, so now we're at 4340 watts without touching a control.