Interesting SAE Research Reports

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SubLGT

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Here are 3 very recent reports re: automotive lighting:

http://papers.sae.org/2017-01-1356/

How to Define Headlamp Light Performance ?
...Experimental test series recently published [are] causing a lot of discussions as [to] the sensitivity of the aiming of the headlamps, [which] can cause completely different performance test results. The paper will report on a study with various production vehicles, all in the same way initially aimed and prepared for all type of technologies…[R. Neumann]


http://papers.sae.org/2017-01-1360/

Investigating the Influence of Headlight Glare and Aim on Risk-Related Driving Behavior
...The results suggest that discomfort from headlight glare, including effects from vertical misaim, could be correlated with increased nighttime crash risk while driving…[J. Bullough]


http://papers.sae.org/2017-01-1359/

Influence Parameters on Headlamp Performance in Rating Systems and Reality
...Basic interest is to understand the performance of the light for a real driver. This article will discuss the influence parameters on achieving a repeatable and precise rating as well as the outer influence that creates glare and varying seeing distance…[M. Hamm]
 
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-Virgil-

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Those (Neumann, Bullough, Hamm) are three of the top names in vehicle lighting/driver vision research. I try not to miss any of the papers they periodically put out.
 
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SubLGT

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3 more very recent SAE papers from Bullough's research group at Rensselaer Polytechnic Institute:

https://www.sae.org/publications/technical-papers/content/2019-01-0850/

Evaluation of After-Market Light Emitting Diode Headlight Bulbs

...Several different LED replacement bulb kits, each designed to replace a conventional 55-W H11 halogen bulb, were purchased and tested in three different low-beam headlight units. Photometric measurements at several critical test points for headlight performance revealed that none of the resulting distributions met all of the test point photometric requirements. Some intensity values were lower than allowed minima while others exceeded allowed maxima....Even though some bulbs more closely matched halogen performance, performance for different headlights using the same LED bulb could vary widely. These findings suggest that using after-market LEDs to replace halogen bulbs can compromise headlighting performance...


https://www.sae.org/publications/technical-papers/content/2019-01-0845/

Influence of LED Spectral Characteristics on Glare Recovery

Headlight glare is a major concern of the driving public. In the past couple of years there have been concerns expressed about the use of light emitting diode (LED) lighting technologies and possible impacts LEDs may have on people, including circadian disruption, retinal hazards, and glare. Under typical use cases, vehicle headlight exposures are insufficient to cause circadian disruption or retinal damage, but can result in disability and discomfort glare, as well as glare recovery..... Although cool white LEDs will tend to be judged as creating more discomfort than warm white LEDs, they do not result in longer glare recovery times under the range of conditions used in this study.


https://www.sae.org/publications/technical-papers/content/2019-01-0847/

Impacts of Flashing Emergency Lights and Vehicle-Mounted Illumination on Driver Visibility and Glare

...With the advent of light emitting diodes (LEDs), emergency flashing lights are brighter and produce more highly saturated colors, thereby causing greater discomfort and disability glare. As a result, first response workers are at higher risk for being injured or killed in vehicle crashes because approaching drivers cannot see them.....While the probability of correctly detecting the police officer figure was affected by intensity, the color of the flashing lights did not matter. Importantly, the presence of low-level white illumination at the side of model vehicle significantly improved detection accuracy.
 
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JasonOk

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While i fully support our emergency workers and law enforcement personal, i'm glad to see I'm not the only one thinking their new dare i say obscenely bright led lights are dangerous
 
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cetary35

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I agree with the emergency vehicle lighting aspect. The systems EMS are using in my area spray strobing glare over whole city blocks...and in blue light to.
 
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The most “poisonous” aspect of LED lights in vehicles is the fact that they emit way brighter light than necessary. To reduce that power manufacturers introduce PWM... Yes, your brain does not register PWM in most cases, but your eyes do! This is why you feel that hardly explainable discomfort and disgust looking at excessively bright LED lamps: they are not only bright, they strobe you. And each pulse of light is way brighter in reality than your brain registers it.

If it was me, I would have banned all PWM driven lights on vehicles as dangerous equipment.

Add here those laser beam scanning headlights... Do you know that scanning laser beam is THOUSANDS of times stronger than you see it?
 
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-Virgil-

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The most “poisonous” aspect of LED lights in vehicles is the fact that they emit way brighter light than necessary.

Interesting assertion. How are you defining "necessary"?

To reduce that power manufacturers introduce PWM

PWM (pulse-width management) is used in a fair number of LED vehicle lights. Some headlamps are dimmed via PWM to provide a daytime running light function. Some daytime running lights or front turn signals are PWM-dimmed to provide a front position ("parking") light function. Some stop lights are PWM-dimmed to provide a rear position ("tail") light function. But the actual headlight functions, the high and low beam, are generally not PWM'd.

Yes, your brain does not register PWM in most cases, but your eyes do!

This assertion is not correct. It does not have a basis in physiology. And yes, the flicker induced by PWM feed of a light source with instantaneous on/off (such as LEDs) is perceptible under particular conditions. If your gaze scans across an LED light being PWM'd below a certain frequency, you'll see what is called the "beads effect", because the light looks like a string of beads. Similarly, PWM'd DRLs can appear to bounce/dance around as seen in your car's mirrors. So far, careful study has not revealed a safety hazard posed by any of this.

This is why you feel that hardly explainable discomfort and disgust looking at excessively bright LED lamps: they are not only bright, they strobe you. And each pulse of light is way brighter in reality than your brain registers it.

Sorry, no. This sounds like it might be a favorite pet idea of yours, but it's not real. There are enormous holes in your understanding, and you seem to have just decided you can fill them and patch together your fractional knowledge with guesses, assumptions, and declarations. That isn't how any of this works.

If it was me, I would have banned all PWM driven lights on vehicles as dangerous equipment.

There's no evidence to support such a claim or ban.

Add here those laser beam scanning headlights... Do you know that scanning laser beam is THOUSANDS of times stronger than you see it?

The strength of the laser beam is irrelevant, because you never see the laser beam, which hits a phosphor plate inside the headlamp, which converts the blue or violet laser light to white light, and that spot of white light is what's used as the headlamp light source.
 
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-Virgil-

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Back to the subject of the thread: the three papers linked in post 3 were presented this past Wednesday in Detroit, along with five others. No real need for me to rehash the summaries already posted, except to remind readers that they're written conservatively. For example, when it says "using after-market LEDs to replace halogen bulbs can compromise headlighting performance", they mean it completely destroys the safety performance of the headlamps -- severely inadequate seeing and/or severely excessive glare. The papers and lectures all generated good discussion, but there were only about 20 people in the room. Attendance at the SAE World Congress lighting sessions is nowhere near what it was 15 or 20 years ago. Compare events like the DVN Workshops where they regularly have 200 to 300 people for a longer program of similar papers, lectures and discussions.
 
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SubLGT

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... The papers and lectures all generated good discussion, but there were only about 20 people in the room. Attendance at the SAE World Congress lighting sessions is nowhere near what it was 15 or 20 years ago...

Did anyone from the SAE lighting task force give an update on their work-in-progress: Forward Lighting LED Substitute Light Sources for Halogen Light Sources ?
 
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Did anyone from the SAE lighting task force give an update on their work-in-progress: Forward Lighting LED Substitute Light Sources for Halogen Light Sources ?

It's the SAE Lighting Systems Group you're asking about. Their next meeting is the end of this month, in Denver, and that topic will be discussed there.
 
XeRay

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PWM (pulse-width management) is used in a fair number of LED vehicle lights.

I was "sure" that PWM was an abbreviation for Pulse Width Modulation, I never heard Management used prior to this.
Please clarify.
 
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-Virgil-

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I was "sure" that PWM was an abbreviation for Pulse Width Modulation, I never heard Management used prior to this.
Please clarify.

Slip of the thumb! "Modulation" is correct. :)
 

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