Film-Tech Forum ARCHIVE: Pulse lamps........

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Posted by Pete Evans (Member # 1823) on 10-13-2003, 05:03 PM:

In the early 70's when I was working at the NFT I was asked to help out at the nearby Queen Elizabeth Hall, which ran occasional films, on this occasion I had to run "Metropolis". The QEH was equiped with Philips DP70's with Pulse lamps, I was wondering whether anyone is still using these, I know that the Classic Piccadilly was also using them at the same time, but I wasn't that impressed and haven't come across any since.

Posted by Erick Akers (Member # 875) on 10-13-2003, 05:18 PM:

What are pulse lamps?
I've never herd of them.

Posted by Hugh McCullough (Member # 1542) on 10-13-2003, 05:53 PM:

Pulse lamps were a Philips invention, and I remember using them at the ABC Croydon when we were testing out the, then, new FP20 projectors in the late 1960s.
The projector was not fitted with a flicker shutter, instead the lamp flickered on and off, being on when the film was stationary in the gate, and off when the film was moving to the next frame.
The idea may have seemed good, but did not work as the lamps life span was not very long, and the constant on-off-on cycle weakened the filament. They were also not very bright, at least not on our 135ft throw.
After about 18 months we installed a flicker shutter, and went back to our Peerless carbon arcs.
The last time I saw one of these lamps in use was on a Philips slide projector sometime in the midd 1970s.

Posted by Steve Kraus (Member # 476) on 10-13-2003, 05:58 PM:

A filament? How could one possibly have a filament flashing at the necessary rate? I could see doing this sort of thing with either a strobe or some sort of pulsed arc but I don't see how it would work with a filament.

Posted by Stephen Furley (Member # 1277) on 10-13-2003, 06:01 PM:

At one time Philips made projectors which, rather than a continuous light source with a shutter to cut of the light during the pull down used a light source which gave pulses of light. The lamps were much smaller than xenons, and I think they may have been water cooled. I think they were some sort of mercury lamp.

I've never seen a set-up using them, but I have seen pictures. I seem to remember that Bernard Tonks had experience of them.

Posted by Hugh McCullough (Member # 1542) on 10-13-2003, 06:12 PM:

Ok. Maybe the lamps did not use filaments, but thats what the engineers called them.
They were much smaller than a xenon being only about 6ins long by about a half inch in width. I do not know if they were filled with any type of gas.
They were not watercooled.
Both the machines and the lamps were prototypes that we were testing.

Posted by Pete Evans (Member # 1823) on 10-13-2003, 06:22 PM:

I think you are right Stephen, I seem to recall they were water cooled, and if I remember correctly they were installed in pairs so that when one failed (as they did often) the other would drop into place, not altogether satifactory. As others have said the flicker shutter was removed, and the lamps flashed on and off.
As I only worked on them for one day about thirty years ago, I can't remember much more, getting old you know!

Posted by Stephen Furley (Member # 1277) on 10-13-2003, 06:31 PM:

How widely used were these things? The first time I heard of them was at college in about 1974, where one of the lecturers happened to mention them. He had used them somewhere, I don't know where, but wasn't very impressed, for the same reasons you gave, Hugh, short life and low light output, also poor colour. He said they were replaced by carbon arcs. Since then I have heard of them several more times, but have never heard very good reports of them.

The two projection lecturers were Ted Church and Harry Court; did you know either of them?

Hugh wrote:

quote:
They were not watercooled.

But Pete wrote:

quote:
I seem to recall they were water cooled

Hugh also said that his lamps were prototypes; maybe the water cooled ones were a later development, to increase the available light output.

Pete, I'm quite surprised that these lamps were still in use in the '70s, maybe as the QEH only ran film on an occasional basis they didn't think it was worth replacing them with something better. I would be very surprised indeed if any were still in use today.

Philips, and later Kinoton were always very innovative, with such things as long run film handling, automation systems, single projector systems etc, and later, of course, platters. Philips are also a very major producer of discharge lamps of various types, so it is not surprising that they would have developed these.

They also made a remarkable projector, with two mechanisms, one above the other, and four 2000 foot spoolboxes. Two projectors in the space of one.

Posted by Per Hauberg (Member # 529) on 10-13-2003, 06:43 PM:

The pulse lamps were, if I am not all wrong, presented together with the first FP20's at the 1956 Photokina exhibit in Cologne, Germany, as Philips' go for automation. Two FP20 projectors with pulse lights and 6000 feet reels automatic change-over was the future small and medium cinema. At the very same exhibition the DP70 was showing "The Miracle of Todd-AO".
The pulse lamps were water-cooled, and due to the short lifetime of the bulbs, a spare bulb was mounted with the one in use, changing automatically to the new one, when the first burned out. Black-out, yes - but the change was quite fast and the lamphouse just "cute". The Philips trade paper "The Elagraph" had an article with pictures from the occasion. Maybe Thomas Hauerslev has got this in his archives to share.

p.

Posted by Hugh McCullough (Member # 1542) on 10-13-2003, 06:50 PM:

I seem to remember that the FP20 projector weas advertised, at least in the UK, as the first shutterless projector, due to them using the Pulse lamp.

Posted by Stephen Furley (Member # 1277) on 10-13-2003, 07:02 PM:

It wouldn't surprise me if they did claim that, but there were shutterless projectors going back at least as far as the '20s.

Posted by Mark Gulbrandsen (Member # 72) on 10-13-2003, 07:16 PM:

The lamms made by Phillips were actually a pulsed Xenon lamp. Each lamp was in a water jacket and also there were two of them in a turrett assembly that allowed you to rotate to a fresh lamp of the one being used failed. Unfortunately they had a short life and as a result interest died out early on. I suspect that this technology could easily be perfected today though.

If anyone knows of one of these machines as being available for purchase please contact me at work.

Mark @ CLACO
801-355-1250 or
cinerama84106@yahoo.com

Posted by Gordon McLeod (Member # 33) on 10-13-2003, 07:23 PM:

Since I probably ran the last pulse light around this was the scope
The lamp was a capiliar mercury lamp with to small electrodes and an ignition filament on the envelope
They ran in a quartz tube that water was pumped through and there were 2 of them on a rotating drum so when one failed the other could be droped in
They synced to the projector via magnet on the intermitent flywheel on some and others had a opto through a sloted disk

The pulsator was a tyrotron device with a rotating commutator

The light output was poor and the colour rendition made the early Marc300 look like a futura 2 in comparison they were very bluey green

I ran a pair of them for years in the late 70's on the back of a pair of FP16's

Posted by Larry Shaw (Member # 388) on 10-13-2003, 09:33 PM:

We have one of these systems in our inventory. Quite a few were in use in Canada until we were no longer able to get the bulbs. It may not have been the finest light, but once again I'd suggest if compared with what else was going on with image illumination technology in the 50's it was very advanced thinking.

Posted by Gordon McLeod (Member # 33) on 10-13-2003, 09:37 PM:

The other problem with them was that there was always a small amount of dual travel gosting both up and down at the same time from the glow of the ignition wire

Posted by William Hooper (Member # 71) on 10-14-2003, 12:13 AM:

quote:
It wouldn't surprise me if they did claim that, but there were shutterless projectors going back at least as far as the '20s.

There was a flashing-light design going farther back than that, pre-dating projection. Anshutz' Electrical Tachyscope used flashes of light from pulsing a Geissler tube (a tube filled with gas caused to glow when excited by high voltage via an induction coil). The Tachyscope was later developed into a projecting model.

http://www.acmi.net.au/AIC/ANSCHUTZ_E_TACH.html

Posted by Frank Angel (Member # 248) on 10-14-2003, 12:15 AM:

What would the advantage of such a pulse light source be over a simple mechanical shutter? I mean, the mechanical shutter is an efficient design that works well (if it ain't broke...etc.) If the pulse light was, say, a colder light that delivered less heat to the film, or if it was brighter than a steady light source, then there would be a reason to entertain its use. But unless I am missing something, I don't see what advantage the pulse light was supposed to bring to the existing system. It had a short life, so much so they had to basically build two in one envelope, it had produced less light than a carbon arc source, it had terrible color temperature and it needed to be water-cooled, and to top it all off, it produced a double ghost!! Good grief, could there be any worse idea just to eliminate a perfectly good mechanical shutter design?

It's almost as bad an idea as installing a $170,000 video projector that produces an inferior picture instead of spending $20,000 for a 35mm film projector.

Frank

Posted by Bernard Tonks (Member # 809) on 10-14-2003, 04:38 AM:

quote:
I've never seen a set-up using them, but I have seen pictures. I seem to remember that Bernard Tonks had experience of them.

There is some information on the Philips Pulse light in the 2001 Film Handler's Forum, Philips/Norelco FP20.

Regret unable to link this thread [Confused]

To quote from a manual, the SSP.800 gas discharge lamp consists of a quartz tube only 3-1/8” (80mm long), 72 impulses per second or three impulses per frame, there of course being no flicker shutter. The average life of lamp was 33 hours under full load. The average bulb life at Bayswater was between 60-70 hours, and many did upto 115 hours. The size of scope screen was 36’. This was in the year 1960, and the lamps were water cooled.

Posted by Stephen Furley (Member # 1277) on 10-14-2003, 06:50 AM:

Thank you Bernard, I thought it was you. I seem to remember you had a photograph of a remote control console for the projectors installed in the auditorium.

How did you find the light output on a screen that size? Was it adequate? Was it equal to what they replaced, Peerless arcs, if I remember correctly? Also, did you find the colour satisfactory?

I find it quite surprising that this idea hasn't been tried again since. Just about everything seems to get re-invented every few years, and discharge lamp technology has moved on a long way in almost fifty years. I suppose the advantages of a pulsed lamp over a conventional xenon are less than those over a carbon arc, so there is less incentive to develop one today.

The top picture on Long run projector shows a long run projector which looks rather similar to the Fedi one in concept, though rather more compact. It seems to be based on an FP-20, with oversized spool boxes, still in the same rather odd shape as the smaller philips ones. Is the lamphouse on this projector one of the pulsed ones?

Posted by Warren Smyth (Member # 1838) on 10-14-2003, 07:05 AM:

Stephen

quote:
How widely used were these things?

Well a couple of pair found their way over this side of the world I believe in the late fifties. One pair at the Plaza in Auckland didn't last more than a few months - poor light and just preceeded the instalation of DP70s for 70mm. They were transfered to a smaller theatre where they ran well into the seventies. I saw the result there on a smaller screen. Again low light with a blue hue.

The other pair were in Queenstown and represented the first automated plant in the country. This aspect is probably what the pulse light will be remembered for. It provided an early means of automation using two projectors, 6,000ft reels and automatic change-over. I think the idea was to enable the manager owner to carry out the duties of projectionist and manager. This was before the days of multiple screens. Automation therefore had a different meaning in those days, but with the carbon arc being the only alternative form of light source, this Philips installation was pretty revolutionary. I believe the system ran sucessfully in the MODERATE sized theatre for quite a while.

Posted by Jeff Taylor (Member # 443) on 10-14-2003, 10:57 AM:

FWIW: The military used the pulse xenon approach for their xenon retrofit kit for the JAN 16's. If memory serves, I believe it was a Hanovia lamp.

Posted by Steve Kraus (Member # 476) on 10-14-2003, 11:57 AM:

Of course if you had an actual strobe rather than a pulsating arc you could dispense with intermittent film motion as well. But it would have to be a heck of a bright strobe to register in 1/100,000 sec. (or whatever it is) what the eye normally integrates over 2 x 1/96 second flashes. I wonder how it would look though. Aren't there lab inspection machines like that?

Posted by Ken McFall (Member # 845) on 10-14-2003, 12:08 PM:

If you look on the fly wheel on the back of the intermittent on some older FP20 projectors you will see the notches that were cut out. A sensor was mounted to see these and they were used to trigger the pulses, three per frame which, giving 72 fps, it apparently gave a very good flicker free image.

I worked at a cinema that had a very early installation, the water cooling system was still there. From what I was told the system worked very well giving a very even light on screen. The momentary blank as the lamps changed over was not really a problem. However the water filters, the lamps were surrounded by water, apparently needed constant checking.

Posted by Stephen Furley (Member # 1277) on 10-14-2003, 12:14 PM:

Isn't that basically what the Edison Kinetoscope did? Ok, not with a strobe, but a continuously moving film and a shutter with just a very narrow slit in it.

Posted by John Pytlak (Member # 331) on 10-14-2003, 04:06 PM:

If you pulsed the lamp at 24 fps, how did you avoid seeing the flicker? Most people are very sensitive to flicker when the rate is much below 48Hz.

Posted by Gordon McLeod (Member # 33) on 10-14-2003, 07:40 PM:

There was a telecine system called syncrolite that used a strobe lamp

Posted by Dave Callaghan (Member # 1544) on 10-15-2003, 12:29 AM:

Pulse lights were installed in at least 3 booths in Toronto that I am aware of - the Ontario Science Centre Great Hall, the Universal screening room, and at an independent cinema, Cinecity.

One of the problems that I understand made them difficult to use in North America was that they were designed to run at 50 hz. For North America, the pulsator had to convert 60 hz to 50 hz, which caused problems.

Posted by Bernard Tonks (Member # 809) on 10-15-2003, 06:41 AM:

Stephen wrote,

quote:
How did you find the light output on a screen that size? Was it adequate? Was it equal to what they replaced, Peerless arcs, if I remember correctly? Also, did you find the colour satisfactory?

It was perfectly adequate for 1.75 wide screen but not for scope with Kalee varamorph heavy light eaters. As I mentioned before, Bausch & Lomb anamorphics should have been used. Without doubt the Peerless carbon arcs gave the better white light. Technicolor prints were only just about satisfactory in my opinion. I do remember a cold slight blue hue on B+W films, which many were in those days (1960). The screen I believe was a new Purlux surface.

The picture on the Philips Long run projector is the model with Pulse lamp.