Acer H226HQL bid -- no PWM?

Reach1
Reach1 Member Posts: 10 New User

I've seen mentioned on a couple of forums that this monitor is unique in its price range for having a backlight that does not use pulse width modulation; in other words, the brightness is altered by direct current and does not cycle on and off.  Is this correct?

Best Answer

  • Tommy-Acer
    Tommy-Acer VIP Posts: 6,317 Seasoned Specialist WiFi Icon
    Answer ✓

    The PWM is for the signal but the backlight does not use PWM.  The backlight uses 5V DC.

     

    Does H226HQL have PWM in backlight dimming/regulation?  No

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Answers

  • Reach1
    Reach1 Member Posts: 10 New User

    I found this article by a site that tested the monitor thoroughly and ascertained that, indeed, it did not have PWM.  (Google Translate is at our disposal.)  Encouraged, I went ahead and bought it.  However, it occurred to me afterwards that the article was written in February and the monitor I received was manufactured in June, and since it's a characteristic that's not mentioned in the specs, it's possible that Acer might have changed things. 

     

    Therefore, if anybody could tell me how I might get in touch with an Acer tech person I'd be most grateful.  I'm thinking about the same model for a relative.

  • Tommy-Acer
    Tommy-Acer VIP Posts: 6,317 Seasoned Specialist WiFi Icon

    My apologies for taking this long to respond, but I wanted to be sure that my information was accurate.

     

    The information that I have been provided from engineering is that, "Yes, the H226HQL does have PWM."

  • Reach1
    Reach1 Member Posts: 10 New User

    Thanks Acer-Tommy for looking into this.  I must say I'm disappointed, and confused also.  I thought I'd found something that might be helpful as far as preserving eyesight.

  • Tommy-Acer
    Tommy-Acer VIP Posts: 6,317 Seasoned Specialist WiFi Icon

    My pleasure.  I'm hopeful that you can find something that works for you.

  • datacons
    datacons Member Posts: 2 New User

    Acer-Tommy, hi!

     

    Could you please check about H226HQL bmid version regarding PWM? Is it somewhat different from H226HQL bid version, or all H226HQL do have PWM?

     

    Thanks a lot!

  • Phen1
    Phen1 Member Posts: 10 New User

    I second datacons's question. I also would like to know if PWM/PWM free backlight in H226HQL bmid depends on model revision, model number (I've seen two so far - UM.WH6EE.002 and UM.WH6EE.001), date of production, region (I live in Russia) and any other possible factor.

     

    Thank you!

  • Tommy-Acer
    Tommy-Acer VIP Posts: 6,317 Seasoned Specialist WiFi Icon

    My above response is in regard to the entire series.

  • datacons
    datacons Member Posts: 2 New User

    Thanks for your reply Acer-Tommy!

     

    There is only only thing I want to confirm with you: does the reply you received from engineering ("Yes, the H226HQL does have PWM.") relates specifically to the backlight dimming or general functioning of the monitor?

     

    As far as I understand all monitors today use PWM in general functioning but backlight can be regulated either using PWM or by changing direct current.

     

    So, could you please confirm that the question you asked to the engineering was something like: "Does H226HQL have PWM in backlight dimming/regulation"?

     

    I am sorry to bother you but in the above mentioned test of this monitor no PWM in backlight dimming was observed. In case it is wrong could you please also request from the engineering what the level of frequency of PWM in backlight dimming of H226HQL is in kHz?

     

    Thanks in advance!

  • Reach1
    Reach1 Member Posts: 10 New User

    I haven't marked the thread as "solved" because I haven't been able to reconcile the fact that two apparently reliable sources have come up with contradictory statements.  There's got to be a deeper story somewhere.  Datacons seems to have a probing tack.

  • Phen1
    Phen1 Member Posts: 10 New User

    I would like to get an answer as well Smiley Happy

  • Tommy-Acer
    Tommy-Acer VIP Posts: 6,317 Seasoned Specialist WiFi Icon
    Answer ✓

    The PWM is for the signal but the backlight does not use PWM.  The backlight uses 5V DC.

     

    Does H226HQL have PWM in backlight dimming/regulation?  No

  • Reach1
    Reach1 Member Posts: 10 New User

    Hooray!  And two kudos expressed.  (And interest in learning more about PWM in monitors stimulated.)

     

     

     

     

  • Phen1
    Phen1 Member Posts: 10 New User

    Acer-Tommy, that's awesome news! I have only two questions:

    1. Does H226HQL bmid use 5V DC in all brightness range (0-100%)?

    2. Are all H226HQL bmid models  wihout PWM or it depends on region, date of manufacture, revision, etc?

     

    Thank you very much for your answers! Smiley Happy

  • Tommy-Acer
    Tommy-Acer VIP Posts: 6,317 Seasoned Specialist WiFi Icon

    1. Does H226HQL bmid use 5V DC in all brightness range (0-100%)?

    • The H226HQL uses 5V DC for the back light and it is not related to the brightness.  Brightness is controlled by the OS.

     

    2. Are all H226HQL bmid models  wihout PWM or it depends on region, date of manufacture, revision, etc?

    • As I noted earlier, all of the H226HQL models are the same.

     

  • Reach1
    Reach1 Member Posts: 10 New User

    Acer-Tommy wrote:

     

    • The H226HQL uses 5V DC for the back light and it is not related to the brightness.  Brightness is controlled by the OS.

     


    This I do not understand.  My assumption was that in such a situation the backlight was dimmed or brightened by altering the DC voltage.  Are you saying that no matter what the brightness is set at the backlight is always at 5V?  If that is the case then what is being altered?  The amperage?  What's the OS you refer to?  Finally, what is the signal you are referring to when you say that the PWM is for the signal.

    Please pardon me, but I believe you are assuming more technical knowledge than the typical forum participant has.  In this case, some of us are still a bit confused and uncertain until we get a little more in-depth explanation.  Thank you much if you would do so!

  • Phen1
    Phen1 Member Posts: 10 New User

    Acer-Tommy wrote:

    1. Does H226HQL bmid use 5V DC in all brightness range (0-100%)?

    • The H226HQL uses 5V DC for the back light and it is not related to the brightness.  Brightness is controlled by the OS.

     


    I am not an engineer and I hardly imagine how the monitors work but according to this link there are monitors that use so called "hybrid solution":

    "PWM free down to 20% brightness, but used at 200Hz below"

    "No PWM down to 20% brightness, but used 19 - 0% at high 8750Hz"

     

    Quote from Dell U2413 review:

    "The PWM tests with the oscilloscope revealed some interesting results. At a setting of 100, 50 and 20% brightness there was a steady voltage applied to the backlight and there was no PWM used. The brightness is continuous between 100 and 20% settings."

    "At a setting of 19% however we started to see the oscillogram spike as you can see in the above image, suggesting there was some cycling of the backlight"

    "If users are very worried about flicker or particularly susceptible to it, then you need to be aware of the use of some form of PWM for settings of 19% and below."

     

    That's why I mentioned brightness range Smiley Happy

     

  • Tommy-Acer
    Tommy-Acer VIP Posts: 6,317 Seasoned Specialist WiFi Icon

    Yes, this topic has ranged well beyond basic technical knowledge, but it started out that way with a discussion of PWM.

     

    At this point we are getting into the basic operation of the monitor which is not something that I'm going to be able to continue discussing. 

     

    My contacts for all of this information have indicated that we are at an end for this particular topic.

     

     

  • Phen1
    Phen1 Member Posts: 10 New User

    I've just realized I forgot to ask about PWM and brightness range. Some monitors use "hybrid solution" for brightness regulation:
    Eizo EV2336W: "PWM free down to 20% brightness, but used at 200Hz below"
    Dell U2413: "No PWM down to 20% brightness, but used 19 - 0% at high 8750Hz"

    What about H226HQL bmid? Is it PWM free for 0-100% brightness? Smiley Happy

  • Reach1
    Reach1 Member Posts: 10 New User

    According to the information in the link that you provided, the H226HQL (they got no more specific than that) was PWM free for the full brightness range.

     

     

  • Phen1
    Phen1 Member Posts: 10 New User

    As far as I understand, PWM at very high frequences can't be registered by equipment from the review. So I want to get Acer's answer to know for sure Smiley Happy

This discussion has been closed.