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IEEE Recommended Practices for Modulating Current in High-Brightness LEDs for Mitigating Health Risks to Viewers : https://standards.ieee.org/ieee/1789/4479/ ht

by _3yjt 1y ago

IEEE Recommended Practices for Modulating Current in High-Brightness LEDs for Mitigating Health Risks to Viewers : https://standards.ieee.org/ieee/1789/4479/ https://standards.ieee.org/ieee/1789/4479/ There is nothing anecdote about flickering in LED light causing health risks.

deleted 1y ago
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demosthanos 1y ago
I am not questioning that certain types of flickering are harmful, so that there's an IEEE standard for how to safely use PWM does not contradict what I said. What I'm asking for is for articles like this that cite numbers and provide tables purporting to quantify the degree of harm caused by various devices to point to where they're getting their numbers from or, if they can't do that, stop making up numbers and assigning things to "harm" scales that they invented themselves based on vibes. Either there's a study showing that 246 Hz flickering poses "Extremely High" health risks or there isn't.
- _3yjt 1y ago
  See my comment on the other reply. > Either there's a study showing that 246 Hz flickering poses "Extremely High" health risks or there isn't. They calculated it using the definition from the standard.
  - demosthanos 1y ago
    Can you please cite the page number where this definition exists? When I search for "extreme" in the standard that the other commenter links to I don't turn anything up, so I'm unclear where that classification is defined.
    - _3yjt 1y ago
      31 and 32 (by the printed page number), in pdf it’s 42
      - Kirby64 1y ago
        The article contradicts the IEEE paper. They list the 'Xiaomi 15 Ultra' as having a 'Moderately High' health risk, and cite it as having a 2.16 kHz PWM frequency at 30-75% modulation depth. The IEEE article has recommended practices that state: 8.1.2.3 Example 3: PWM dimming Using Figure 20, the recommended practice for PWM dimming at 100% modulation depth is that the frequency satisfies f > 1.25 kHz. This can also be derived using Recommended Practice 1 and solving 100% = 0.08×fFlicker. This level of flicker could help minimize the visual distractions such as the phantom array effects. Seems like even at 100% mod depth, >1.25 kHz is just fine. Also, the article does not seem to distinguish between modulation at reduced brightness, which the IEEE article calls out specifically as something that is unlikely to cause issues. E.g., movie theaters using film all flicker at 48 Hz and nobody complains about that.
      - demosthanos 1y ago
        That does not define the scale that they're using. That's a typical hazard analysis risk matrix which has two axes which can be converted into a 4-point scale (Low, Medium, Serious, High). Importantly, to do a risk assessment in the style of IEEE 1789's you have to identify the specific Hazards that you're analyzing, which TFA does not claim to be doing in that table, instead speaking vaguely of "health risks". IEEE 1789 does not provide a mechanism for evaluating "health risks" without specifying exactly which risks are being evaluated. You can see on page 27 how this is meant to be used: it should produce a per-hazard matrix. You might be thinking of Figure 18 on page 29, which does identify Low-risk and No-effect regions by Modulation % and Frequency, but that also does not claim to identify high-risk regions, it just identifies the regions we can be highly confident are safe. And importantly, as a sibling comment notes, TFA's table actually contradicts the line on Figure 18, labeling several devices as higher than Low even when they're squarely within the Low-Risk and No-Effect zones.
- PaulHoule 1y ago
  Was it an astronomically high health risk to watch a TV set that flickers at 60 Hz or movies that flicker at 48 or 72 Hz? (It is 24 frames per second but you'd perceive a lot of flicker at that rate so the shutter has 2 or 3 blades)
wasabi991011 1y ago
Here is a non-paywalled link: https://www.lisungroup.com/wp-content/uploads/2020/02/IEEE-2015-STANDARDS-1789-Standard-Free-Download.pdf https://www.lisungroup.com/wp-content/uploads/2020/02/IEEE-2... Sure, PWM light can cause health risks for some people, in some contexts. But taking research out of context is bad science. Do you genuinely believe the Pixel 7 and 8 Pro have an "extremely high health risk", in the context of what a lay person would understand? Edit: I specify 'lay-person' because clearly this is an introductory blog post (or advertisement for Daylight Computer). If they want to use a more specific definition of health risk, then they better define it.
- _3yjt 1y ago
  The “very/moderate high” comes from the standard itself, which is quantified within the standard. In the context, it is about the probability of having issues, while the effect (mild to catastrophic) is another axis. Considering that they stick to the “official” wording and seeing the criticism, I am not even sure if they can change to a more “lay-person” friendly and be acceptable to all the critics. The standard also linked to the researches during their discussion. Please read it, instead of just randomly throw out things hoping that they supported your argument.
  - demosthanos 1y ago
    You can't just point people at a 60-page paywalled standard and say "the supporting evidence to my claim is somewhere in here, I pinky promise". You are the one making assertions, it's on you to prove that the standard actually does reflect the text of TFA. I'm not going to read the whole standard because I'm not the one making the argument and I can't be bothered doing the research needed to refute every piece of nonsense science that shows up on the internet. What I can do is point out when someone is making unsourced claims and insist that they provide their sources if they want to be taken seriously. Cite the exact page number and quote that you claim justifies the assertion that 246 Hz PWM carries an "extremely high" health risk. Then we can talk.
    - _3yjt 1y ago

by _3yjt 1y ago

deleted 1y ago

[deleted]

demosthanos 1y ago

I am not questioning that certain types of flickering are harmful, so that there's an IEEE standard for how to safely use PWM does not contradict what I said. What I'm asking for is for articles like this that cite numbers and provide tables purporting to quantify the degree of harm caused by various devices to point to where they're getting their numbers from or, if they can't do that, stop making up numbers and assigning things to "harm" scales that they invented themselves based on vibes. Either there's a study showing that 246 Hz flickering poses "Extremely High" health risks or there isn't.

_3yjt 1y ago
See my comment on the other reply. > Either there's a study showing that 246 Hz flickering poses "Extremely High" health risks or there isn't. They calculated it using the definition from the standard.
- demosthanos 1y ago
  Can you please cite the page number where this definition exists? When I search for "extreme" in the standard that the other commenter links to I don't turn anything up, so I'm unclear where that classification is defined.
  - _3yjt 1y ago
    31 and 32 (by the printed page number), in pdf it’s 42
    - Kirby64 1y ago
      The article contradicts the IEEE paper. They list the 'Xiaomi 15 Ultra' as having a 'Moderately High' health risk, and cite it as having a 2.16 kHz PWM frequency at 30-75% modulation depth. The IEEE article has recommended practices that state: 8.1.2.3 Example 3: PWM dimming Using Figure 20, the recommended practice for PWM dimming at 100% modulation depth is that the frequency satisfies f > 1.25 kHz. This can also be derived using Recommended Practice 1 and solving 100% = 0.08×fFlicker. This level of flicker could help minimize the visual distractions such as the phantom array effects. Seems like even at 100% mod depth, >1.25 kHz is just fine. Also, the article does not seem to distinguish between modulation at reduced brightness, which the IEEE article calls out specifically as something that is unlikely to cause issues. E.g., movie theaters using film all flicker at 48 Hz and nobody complains about that.
    - demosthanos 1y ago
      That does not define the scale that they're using. That's a typical hazard analysis risk matrix which has two axes which can be converted into a 4-point scale (Low, Medium, Serious, High). Importantly, to do a risk assessment in the style of IEEE 1789's you have to identify the specific Hazards that you're analyzing, which TFA does not claim to be doing in that table, instead speaking vaguely of "health risks". IEEE 1789 does not provide a mechanism for evaluating "health risks" without specifying exactly which risks are being evaluated. You can see on page 27 how this is meant to be used: it should produce a per-hazard matrix. You might be thinking of Figure 18 on page 29, which does identify Low-risk and No-effect regions by Modulation % and Frequency, but that also does not claim to identify high-risk regions, it just identifies the regions we can be highly confident are safe. And importantly, as a sibling comment notes, TFA's table actually contradicts the line on Figure 18, labeling several devices as higher than Low even when they're squarely within the Low-Risk and No-Effect zones.
PaulHoule 1y ago
Was it an astronomically high health risk to watch a TV set that flickers at 60 Hz or movies that flicker at 48 or 72 Hz? (It is 24 frames per second but you'd perceive a lot of flicker at that rate so the shutter has 2 or 3 blades)

wasabi991011 1y ago

Here is a non-paywalled link: https://www.lisungroup.com/wp-content/uploads/2020/02/IEEE-2015-STANDARDS-1789-Standard-Free-Download.pdf https://www.lisungroup.com/wp-content/uploads/2020/02/IEEE-2... Sure, PWM light can cause health risks for some people, in some contexts. But taking research out of context is bad science. Do you genuinely believe the Pixel 7 and 8 Pro have an "extremely high health risk", in the context of what a lay person would understand? Edit: I specify 'lay-person' because clearly this is an introductory blog post (or advertisement for Daylight Computer). If they want to use a more specific definition of health risk, then they better define it.

_3yjt 1y ago
The “very/moderate high” comes from the standard itself, which is quantified within the standard. In the context, it is about the probability of having issues, while the effect (mild to catastrophic) is another axis. Considering that they stick to the “official” wording and seeing the criticism, I am not even sure if they can change to a more “lay-person” friendly and be acceptable to all the critics. The standard also linked to the researches during their discussion. Please read it, instead of just randomly throw out things hoping that they supported your argument.
- demosthanos 1y ago
  You can't just point people at a 60-page paywalled standard and say "the supporting evidence to my claim is somewhere in here, I pinky promise". You are the one making assertions, it's on you to prove that the standard actually does reflect the text of TFA. I'm not going to read the whole standard because I'm not the one making the argument and I can't be bothered doing the research needed to refute every piece of nonsense science that shows up on the internet. What I can do is point out when someone is making unsourced claims and insist that they provide their sources if they want to be taken seriously. Cite the exact page number and quote that you claim justifies the assertion that 246 Hz PWM carries an "extremely high" health risk. Then we can talk.
  - _3yjt 1y ago