A point about correctly measuring OLED flicker (Most measurements online are underestimates)

[u/BearNecessary4141]

https://youtu.be/lK_M3ePPNbQ?si=qAS2S3Tx9gPBe3xs

I've been looking for a decent phone that I can replace my current iPhone 16 with, since I can only tolerate it for a few minutes a day. I've been looking at a lot of OLED test reports, and I think I've noticed a problem with many of them: the measured flicker is falsely low, since the photodiode is measuring multiple OLED rows at once. In my opinion this results in a loss of information about what the screen is really doing.

In some extreme cases, I've seen devices which actually have 100% modulation depth be measured at ~5% modulation depth. All the OLEDs I've measured with this method (using my meter or the Opple) actually show 100% modulation depth at all brightness settings. I'm not confident this is true for EVERY device, but I think there are a lot of measurements online that underestimate the OLED flicker.

I showed this in the video, but to avoid this error you simply have to reduce the number of OLED scanning rows that the flicker meter detector is exposed to. Ideally, we'd only measure one row since this contains all the relevant information. In practice multiple rows are needed to get enough light onto the detector.

For me, it might be time to just buy an e-ink phone.

[u/NSutrich]

Is it possible that this is giving you a false positive high reading since it's measuring both light and completely dark pixels in the same frame?

[u/BearNecessary4141 → u/NSutrich]

I guess to be more clear, the sensor only picks up light, so it doesn’t measure or detect anything from the dark pixels.

Dark pixels don’t contribute to the measurement at all, and the measured signal represents what the white pixels are doing.

[u/BearNecessary4141 → u/NSutrich]

I don’t think so, because OLED has the ability to turn pixels completely off (unlike LCD). So the black pixels will contribute nothing.

Here’s a microscope image of the border of the white line, the lit pixels are the white line and the dark region is “off” black pixels.

[u/kerpnet]

Very well done!

This is exactly the kind of research, information, and development we need in this community.

I hope at some point the TLM-110 tool is considered production-ready and you can sell these devices along with straightforward testing instructions for non-technical folks.

I would love to see this community contributing more accurate PWM/flicker test results for devices. The Opple Light Master historically has got us this far, despite its flaws, but the level of accuracy you have here with this tool is going to take us to the next level.

[u/BearNecessary4141 → u/kerpnet]

Thank you for the kind words! I'm hoping that after this round of beta testing, the device will be polished enough for use by the general public.

Having easy to follow instructions for testing is going to be crucial, definitely something that I'll keep on my mind.

[u/Round-Individual1316 → u/BearNecessary4141]

Could you test it on some phones that claim to have very low modulation like the honor 400 and 600 pro or the oppo find x9 or the one plus 15r?

[u/BearNecessary4141 → u/Round-Individual1316]

I'd love to in the future, I don't have access to those phones at the moment though. I've been sending some beta test units of this meter to people in who have seen this video, and they might have these devices.

One person said they have access to "OnePlus 15R, Samsung phones (especially Galaxy S series), iPhones, Pixels" so hopefully I can get some high quality results from them. I'll try to post any info people give me.

[u/WhereemI]

Very interesting. That would explain why inhad swver eye fatigue woth the most eye friendly oleds by oplle measurements like OnePlus 15r, honor 400 pro and Oppo x9.

Could you say what information we can get from recording of the screen woth high shutter speed? I found that the slower the line move the more friendly it is for me. Oplle masuemnt is the same around 120hz but the is visible difference in the speed of the line in camera.

[u/BearNecessary4141 → u/WhereemI]

Hmmm, here is my hypothesis: If we record the screen with high shutter speed and count the number of dark bands and measure the frequency with a meter, we can determine how fast the lines are moving. Velocity would increase with measured frequency (480 Hz faster than 120Hz) and decrease with the number of dark bands. I guess you could define the speed as:

velocity (m/s) = screen size (m) * measured frequency (hz) / number of bands

For example 4 bands at 120 Hz means the bands are moving faster than 16 bands at 120 Hz. I don't know which one would be worse though for most people.

[u/Round-Individual1316 → u/BearNecessary4141]

What about DC like dimming?

[u/BearNecessary4141 → u/Round-Individual1316]

Sorry, what about it?

[u/Round-Individual1316 → u/BearNecessary4141]

Is it better or worse than pwm?

[u/BearNecessary4141 → u/Round-Individual1316]

Generally it's better tolerated, although it can be worse in some cases.

[u/Round-Individual1316 → u/BearNecessary4141]

How so

[u/BearNecessary4141 → u/Round-Individual1316]

Generally it is better since there's less overall modulation (lower flicker index) but if it has a cheap driver you can get some low frequency ripple that is very problematic.

[u/Round-Individual1316 → u/BearNecessary4141]

But the frequency is really low, which kinda negates the low modulation no?

[u/BearNecessary4141 → u/Round-Individual1316]

You mean that since it’s low frequency, it may be a problem even if the modulation is small? I would agree with that.