M
matix

  • Dec 9, 2021
  • Joined Dec 7, 2021
  • In Electromagnetic interference - cause of flicker and eye strain?

    Mrak0020 Do you have any save tech right now to at least let your eyes heal after bad tech and tests?

    Unlike others, I can't explicitly determine whether a hardware is good or bad. I feel that my old CCFL monitor is better than any notebook screen which I tested. But I feel that it still is not perfect. I currently use this old monitor connected to my new notebook through HDMI-VGA adapter.

    In the past I used this CCFL monitor with my very old desktop computer and it didn't cause any discomfort. Back then I was also not sensitive to any artificial lighting. Incandescent bulbs, fluorescent lamps and diodes did not cause any discomfort - I had perfectly healthy eyes.

    Mrak0020 I wonder what happened first: you purchased that notebook and later noticed a problem with light sources, or vice versa?

    I noticed the problem with eyes about 3 months after I started using new notebook (but I don't remember exactly). My first symptom was that I had to set very low brightness on the notebook screen. I remember that once my friend (we were doing something together on my notebook) asked me to increase brightness. I replied that I can't because my eyes hurt on greater brightness. He was puzzled because the brightness was very low. I started noticing photophobia (light sensitivity) several years later. But sunlight still does not cause discomfort for me. Also sometimes I don't have discomfort in places where there is romantic lighting - many low-brightness lamps which evenly and dimly illuminate the room. Discomfort is the least if I don't see the source of light directly (the lamps directed to the ceiling and covered).

    Back then I did not connect my problems with changing computer because symptoms did not start immediately and on low brightness I had no discomfort. So i was just using low brightness and I accustomed to it. Also I did not change computer immediately - for a certain period, I used both computers.

    I am still not sure if the notebook was the cause of my eye problems. I remember that I started using energy-efficient lighting (fluorescent lamp) in my home about 7-11 years ago (I don't remember exactly when) for the first time in my life. I suspect that it could also affect my eyes. Before that I always used only incandescent bulbs in my home.

    Mrak0020 I saw couple of reports that low contrast help - with the exact problem I am facing - on some devices, but not all.

    Reducing the contrast on my monitor simply reduces the brightness. That's why it helps me.

        • In Electromagnetic interference - cause of flicker and eye strain?

          Mrak0020 Do I understand correctly that you have no clues at all if your cause is hardware or software?

          Yes, I'm still not sure if all these symptoms are caused by my eyes. I have carried out too few tests yet, because my symptoms are not so clear and not so unambiguous and start with delay.

          But I'm sure that all artificial light sources (except sunlight) are much more unpleasant for me than for my friends. This is the most severe if the light source is in my field of view (especially at the bottom of my eyes). All diodes are very unpleasant for me (for example diode signaling that a monitor is powered up) so I often cover them using insulating tape.

          I also remember that my eye problems and other symptoms stared about 8 years ago when I started using new notebook. Ophthalmologist only said that it is dry eye syndrome in those days. I've never had any problems with my eyes before.

          I also have a feeling that using my old CCFL monitor is less tiring for my eyes. However it is still uncomfortable and I set brightness and contrast to very low levels (much lower than my friends) and it helps significantly. I would like to find a monitor that will be less tiring for my eyes. And also I would like to find lightning that is less tiring for my eyes. I use traditional incandescent bulbs, but sometimes (not always) I can even see as they flicker with naked eye (probably when there is higher noise in electrical network).

          Maybe I have much milder form of eye strain so I do not notice symptoms immediately but fatigue accumulates.

            • In Electromagnetic interference - cause of flicker and eye strain?

              Mrak0020 Simple check: if there's no strain when person turns away from the screen but stays within the same distance from electromagnetic source, it is not electromagnetic interference.

              Hi!

              You probably did not understand my post or I did not write it clearly.

              I do not suggest that EMI directly affects the human body (although maybe it is also possible for some people - I don't know). I suggested that EMI may affect the monitor and cause flickering or other noise - as I explained in the real life example.

              Your simple check is good at the beginning. However it is not perfect. It will not exclude the possibility that only the combination of two factors (EMI plus light from the monitor) causes eye strain. But I think that it is more likely that EMI simply affects the monitor and in turn the affected light from the monitor causes eye strain.

              mike First of all, it would be nice if you write about your eyestrain problems.

              Hi!

              I have not yet understood my eye problems. My symptoms are not so clear and not so strong as other people have. I do not feel eye pain. My eye symptoms do not appear immediately. But looking at monitors and any other light sources (except sunlight) is unpleasant and tiring for me. If I use a new notebook for a longer time (a few days or weeks), I fell tired/exhausted and I have brain fog, concentration problems, attention problems, memory loss and forehead pain (symptoms that appear when brain is exhausted - similar as in ME/CFS), but I don't have direct and strong eye pain as other people in this forum. Instead if I use my old CCFL monitor (connected to the same new notebook), I feel that I am much less tired and much less exhausted and I have much more energy. But my symptoms does not change immediately after changing the hardware. I can easily use bad hardware without any symptoms and only after a few days it turns out that I'm exhausted. And regeneration also takes several days.

              Because my symptoms do not appear immediately and are not so strong and distinct, I am not able to easily compare hardware (and evaluate which is bad and which is good). That's why I try to understand what causes the problem to choose the equipment that will cause as little fatigue as possible.

              mike If the cable is broken!?

              I do not have such problem with HDMI cable. I wrote it on the basis of what I read in the "HDMI vs. VGA cable and eyestrain" topic in this forum.

              mike How did you turn it off? I really want a answer to that question! And their is more techniques with rendering, so you can’t know that for sure.

              I don't know for sure. I wrote this also on the basis of what I read in this forum. Other people performed test for dithering using external HDMI recorder. There is for example "Temporal Dithering Testing" topic in this forum. Maybe testing was not performed correctly, but I don't know.

              xelaos This is for example not true for me. I still have problems with VM or remote Desktops depending on resolution/framerate/fonts/animations/colors etc which I for example don't have with one eye closed or if other software related factors change.

              I understand. Probably there are many different causes which gives the same symptoms (eye strain, etc). But I remember that someone wrote that he can use linux in virtual machine without any problem and he can't use it when running as host operating system.

                        • In Electromagnetic interference - cause of flicker and eye strain?

                          People in this forum describe many different factors that affect whether eye strain occurs. However they usually fail to isolate one main factor which decides about it, because this depends on many different factors that affect each other. Monitor, computer, GPU, operating system and even HDMI cable affect whether there is eye strain or not. The fact that eye strain occurs depends on all factors taken together and how they affect each other. You can not find a monitor or a computer that will ensure no eye strain.

                          Often a monitor works well with one computer and the same monitor works badly with another computer. And vice versa often one monitor causes eye strain and another not even if they are connected to the same computer. So you cannot say that the cause is only monitor or only computer. Sometimes even HDMI cable used for connection decides whether eye strain will occur. Furthermore, often eye strain occurs only when using certain operating system or driver and does not occur while using another operating system (even if computer and monitor are the same).

                          People say that if they use this "bad" operating system in a virtual machine or via VNC, their eye strain does not occur. So the cause in this case are not colors/animations/fonts/pixels displayed by the operating system. The reason is also not temporal dithering, because even if it is turned off (and it was tested that it is actually turned off), the "bad" operating system still causes eye strain when running as host system and does not cause eye strain when running in virtual machine. So in this case eye strain is not caused by pixels (image) displayed by a given system, but it must be caused by something else.

                          Here are some interesting and surprising cases that affect eye strain:

                          HDMI cable: https://ledstrain.org/d/214-hdmi-vs-vga-cable-and-eyestrain/

                          Power supply: https://ledstrain.org/d/1106-intel-hd-graphics-eyestrain-and-using-laptop-without-power-supply-as-solution

                          Partitioning scheme: https://ledstrain.org/d/1087-i-am-using-linux-comfortably/15

                          Based on posts on this forum, I suspect that a very important factor affecting eye strain is electromagnetic interference (EMI). Electromagnetic interference can obviously cause flickering of backlight or pixel (they will dim and brighten with the frequency of interference). Electromagnetic interference is transmitted through air only for very close distance (because power falls very quickly), but it is also very well transmitted through each metal wire for long distance (even if that wire is not connected to anything and simply lies nearby). Even if the HDMI cable uses digital signal that transmit data without losses, the electromagnetic interference noise is still transmitted by this cable from computer to monitor and from monitor to computer. Thus high frequency electromagnetic noise generated by a new processor or GPU or SSD drive is transmitted through HDMI cable to the monitor. Even if the monitor would be wireless or connected via optical fiber (but such technologies probably do not exist), the electromagnetic noise still would be transmitted through electrical network in the building.

                          Once I observed an interesting phenomenon. When I connected a 5V power supply to an electric socket, my monitor began to flicker (it was not eye strain, but a very strong flickering that was clearly visible to every person). This happened even if this 5V power supply was connected far from the monitor in a completely different room. After disconnecting the power supply, the monitor stopped flickering immediately. The only logical explanation in this case is "dirty electricity" (harmonics and transients generated primarily by electronic devices and by non-linear loads) transmitted through the electric network in the building. So even if my neighbor in his apartment connected that power supply to the electric network, the monitor in my apartment would probably be flickering.

                          Therefore, I suppose that electromagnetic interference is really important factor influencing eye strain. Computer (CPU, GPU, hard drive, etc), monitor and operating system affect which frequencies of electromagnetic interference are generated. Different monitors can be affected differently by different electromagnetic noise frequencies (for example LED could be affected differently than CCFL) hence the difference in symptoms on different devices.

                          An easy way to hear low frequency electromagnetic interference is AM radio. Just put the radio near computer, monitor or HDMI cable. In this very simplified way, you can compare noise generated by different hardware and software.

                          What do you think about it? Maybe connecting monitor or computer to double-conversion UPS (which filters dirty electricity) would sometimes help?

                          • mike replied to this.
                          • In HDMI vs. VGA cable and eyestrain

                            JTL

                            This is definitely possible. See this video: https://www.youtube.com/watch?v=r04DYZ1-BXE

                            I used to have a bad quality HDMI cable that caused the monitor very much flickered (so much that it was clearly visible to every person). Flickering was much smaller during pressing HDMI plug into the monitor. So in this case probably the plug was defective.

                              dev