light color,auto vs photo lighting

Philips, I believe, was working on this.

That was from a Sylvania engineer who was working on what became the DC (Type 9500) HID system used not-briefly-enough in a couple of Lincoln models.

Reply to
Daniel J. Stern
Loading thread data ...

Well, sure! The human visual system is a lousy judge of its own performance. All it takes to generate highly favourable subjective ratings of headlamps is high levels of foreground light.

Reply to
Daniel J. Stern

I must admit I have not seen a spectral curve of an HID headlamp, but I would be rather surprised if the xenon made any significant contribution to the spectrum when the lamp was fully warmed up. In normal metal halide lamps the mercury output is just about nil when the lamp is hot enough for the metal halides to be vaporized. The energy levels of xenon are higher than Hg so the xenon should have less contribution to the spectrum that the Hg in normal metal halide lamps.

The moveable bulb shield is necessary for reasonable lamp life and performance irrespective of the size issues. If two separate arc tubes were used, or like the two filaments in an incandescent headlamp, or even separate high and low beam lamps, the arc tubes would have to be constantly switched on and off as the driver switched from high to low beam and back again. When GE was working on HID headlamps, some of the staff at Nela Park tried to convince me that people didn't change from high to low beams that often so this would not be a problem. These folks lived in a medium size city and drove either on well lit city streets of divided highways. Perhaps they never used their high beams. I live in a semi-rural area and drive on two-lane roads that have no street lights. On a typical 10 mile trip to the nearest mall, I may switch between high and low beams 10 to 20 times.

Reply to
Victor Roberts

But would you say that adding Xenon increases light output during the initial lamp warmup? The only other HID experience I have is with high output HID lighting like garage or stadium lighting where the light color has much less blue but the warmup time until full intensity is much longer than for automotive HID. I do watch the spectrum of HID headlamp bulbs as they start and warm up. It definitely changes over time until thermal stability sets. Whether it's because of the added Xenon or for another reason I can not say for certain, but that is what I had been told.

Unless the lower beam HID stays on all the time and a halogen lamp in a second cavity is used for upper beam, which is what the first generation of vehicles with HID lamps used, as well as a number of current models. As an aside, this is given as a "legitimate" reason for having blue-tinted halogen bulbs - to have a better color match to the HID lamps in use.

Also, a separate HID upper beam wouldn't work well when on for short durations - a "flash-to-pass" would be ineffective since the startup intensity is lower than its warmed-up intensity.

Another technology that was (or is still being) investigated is using a magnetic field to change the position of the arc-filament, much like a two-filament halogen headlamp bulb, so that the same bulb can be used to provide both lower and upper beam functions. Much more difficult, but it has the advantage of no moving parts to potentially fail.

But if you look at all vehicles as a whole, the majority of nighttime driving is with the lower beam. This is really only an argument against developing a separate HID upper beam, and possibly determining which is more economical - using a switchable bulb shield to create an upper beam from the lower beam cavity or having a second cavity with a halogen bulb for upper beam.

Reply to
Douglas G. Cummins

For sure. That's why it's there, as you originally said, to satisfy the technical and legal requirement for immediate light upon activation.

The colour shift as they warm up is primarily due to the vapourisation of the halides in the arc chamber, with secondary effects from the yellow pool of molten halides in the bottom of the chamber.

Yep, this is cited as a reason, and I'd've put those same scarequotes around "legitimate". Chasin' a dragon that can't be caught. A halogen bulb filtered to create even a vaguely close colour match to HID tends to run afoul of minimum-flux, maximum-wattage and/or colourimetry requirements, as I'm sure you've seen in your own lab. A few carmakers (Lexus...) seem to have clued into the idea of using selective yellow fogs on models with HIDs to avoid the clashing appearance of two different whites being emitted from the front of the car. It solves the problem, and it even makes the HID headlamps look bluer, which of course is all the rage. Everyone's happy as long as the selective yellow light is made with Cadmium-free materials!

True. Some vehicles in Europe have such a setup, though.

OSI was playing with this idea some years back. As far as I am aware, they gave up on it due to excessive difficulty reliably controlling the two positions of the arc over the service life of the bulb.

DS

Reply to
Daniel J. Stern

Sure, but you and I are atypical. It's been found repeatedly that in North America at least, drivers tend not to use high beams even when the situation makes them the appropriate choice. (I might add that too many of them use high beams when they're situationally INappropriate...)

Reply to
Daniel J. Stern

The Toyota Prius sold in the US from '01-'03 (four-door sedan body style) has plain old 9003 lamps. The '04 and up (four-door hatchback) have HID lamps. I _think_ all of the Insights and the early Accord hybrids had regular halogen lamps. Pure battery-electric cars often tend to be home-built, and HIDs are probably popular - every watt you don't put into the headlights gets you another 0.2" down the road.

Matt Roberds

Reply to
mroberds

Yes. That is why it is used.

There have been a number of discussions about using magnetic fields to position the arc in the past. Perhaps even a patent.

Not mine. I drive mostly on roads that do not have any street lights. I use my high beam all the time except when another car is approaching. I don't generalize my experience to the whole population and I don't think others should either.

Reply to
Victor Roberts

I can agree that frequent high beam use my be atypical, but if only 30% or even 10% of drivers use their headlamps as I do and the HID headlamp system was designed to switch on and off as high beams were needed there will be a very large number of failed HID headlamps.

Reply to
Victor Roberts

I have seen it, but I am not tellin :-))

Vic is right. After the lamps warm up, the Xenon does not make a significant contribution.

It's one of the SD's for metal halides on my spectra page:

formatting link
[snip]>

Reply to
Ioannis

...as optional equipment, with 9003 (H4) lights being standard. The HIDs aren't available on the Prius in Canada; they all have 9003s up here.

Correct, in North America.

Reply to
Daniel J. Stern

Here's the newest burner (D4 Hg-free). It contains more blue than the now-standard D1/D2 lamps:

formatting link

Reply to
Daniel J. Stern

I have diffraction gratings and I have seen the spectra of metal halide lamps - automotive and otherwise.

There mercury spectrum I usually (not always) find to be a least a little significant, although always a minority of the output (except sometimes not if the lamp is aged excessively or improperly operated.)

The xenon in automotive ones has no contribution to the spectrum that I can see when the lamp is warmed up.

- Don Klipstein ( snipped-for-privacy@misty.com)

Reply to
Don Klipstein

Such as those IQ-challenged individuals who think it's appropriate to travel in heavy daytime highway traffic with every bulb in their front end blazing at maximum brightness...right into my rear view mirror.

Reply to
Hugo Schmeisser

Surely a difference of 40W (20 on each side) is pretty negligable when compared with the power required for propulsion? Off the top of my head, I believe that the engine in my (small) car has a rated output of around

40kW.

Personally I think that the major driving force behind HID headlamps is as a status symbol, with perhaps a secondary nod to the fact that it shouldn't be necessary to change the lamp within the lifetime of the car (am I right here? And will the ballasts need changing instead at much greater cost than a halogen lamp?)

Reply to
Simon Waldman

If they designed HID to have the same light output as the tungsten halogen and then used equally efficient optics the power savings would be greater.

I agree.

This advantage was discussed at GE during the HID headlamp development program. The fact that the lamps would be designed to last for the life of the car also eliminated the need to make them user-replaceable. Some at Nela Park claimed this would reduce the length of the whole car by at least 2" - which will it does is free up a few inches behind each headlamp :-)

They shouldn't. Remember that the operating life of a car is very short compared to other electronic systems we use. If you have an average speed of 30 miles an hour and assume cars die after 100,000 miles (yes, I know many currently last longer) then the car has only operated for 3000 hours! If your average speed is greater the life in hours is less. If the mileage is greater then the life in hours is obviously longer. However, most cars that run for more than

100,000 miles were driven at average speed over 30 miles per hour, so the operating life is still less than 5000 hours in almost all cases.
Reply to
Victor Roberts

In Canada we have that problem *AND* the opposite problem: People driving round at night with only their Daytime Running Lamps (or DRLs + parkers/tails). Grossly insufficient seeing for them, and in many cases greatly increased glare for other road users. Most of this problem would disappear immediately if CMVSS108 were changed to call for the instrument panel lights not to illuminate except with HEADLAMPS (not parkers alone).

Reply to
Daniel J. Stern

Hard to believe how badly I can garble things I type. The last sentence of the paragraph above should have read:

Some at Nela Park claimed this would reduce the length of the whole car by at least 2" - while all it does is free up a few inches behind each head lamp.

Reply to
Victor Roberts

That would only be reasonable if it were headlamps OR front foglights.

Reply to
Bernd Felsche

And *that*, in turn, would only be reasonable if front fog lamps were performance-regulated such that their use without headlamps, in applicable weather conditions, was safe. As it stands, many or most fog lamps available on North American-market vehicles are cosmetic toys, not useful lighting devices, therefore unsafe under any circumstances as the sole forward illumination devices.

Reply to
Daniel J. Stern

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.