flicker

Discussion in 'Hardware' started by kurt corbin, Sep 3, 2019.

  1. kurt corbin

    kurt corbin Scribbler - Standard Member

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    PWM is supposed to be the main cause, but according to notebookcheck, “some devices do not use PWM at all, but still showed a measurable brightness flickering during our review (e. g. poor shielding of the power adapter).” How do they know the cause was something other than PWM, since by their editor’s own admission in their forum, they have no way of knowing whether any given display uses PWM:


    The problem is that it’s a standard industry practice to use displays sourced from multiple manufacturers for the same laptop. So while the unit we test might be PWM free, the next one under the same model name might have PWM - while they should be identical on the specsheet, in reality, they are not.

    This is a problem impossible to solve for us. We at Notebookcheck cannot test every single Notebook on earth and its almost always impossible to tell how many different display panel variations there are for a product, because the manufacturers are mostly intransparent about this stuff.

    In the end, it’s the manufacturers who are not transparent about their products. It’s their task to make more honest spec-sheets and inform people about their products.


    But OK, I get it that there are other causes, like the power adapter. Anybody know of more?


    Notebookcheck claims that PWM is a necessary evil: “New technology such as what is found in smartphones is too small and designed to use too little power to utilize any alternatives such as analog controllers.”


    Yet, for years, they have tested numerous smartphones with no flicker. How did the manufacturers accomplish this if analogue controllers are not an option? Dear notebookcheck, please get your story straight because elsewhere you report that they ARE an option:


    “…manufacturers such as Xiaomi and OnePlus decided to offer DC dimming in their devices with AMOLED displays on a trial basis. We have already examined the effects of the new technology (called Flickering Protection by Xiaomi)…”


    Actually, the DC dimming is used in combination with PWM. Moreover, it seems to be doable with a firmware update.


    Any thoughts? What’s the deal on this supposedly huge analogue controller that is too large to fit in a smartphone, but seems to be in them anyway?
     
    Last edited: Sep 3, 2019
  2. kurt corbin

    kurt corbin Scribbler - Standard Member

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    Looks like this new DC dimming is not done with hardware:

    "DC dimming control uses a DC voltage between 0 and 10 to control the light output of the OLED panel. As the voltage goes up or down, the corresponding 0-10V dimmable driver matches the light output of the fixture to increase or decrease up to a certain percentage.....The Mi 9 and Reno use a software pattern to reduce the low-brightness strobe. Xiaomi is reportedly still developing a new pure hardware DC dimming."

    https://www.oled-a.org/oledrsquos-c...g-to-improve-low-luminance-images_051319.html
     
    WillAdams and thatcomicsguy like this.

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