Okay, Let's Talk About This Second Screen For A Minute - LG V10 Q&A, Help & Troubleshooting

(I'm on the T-mobile variant)
I will be the 1st person to admit that my knowledge of mobile displays is limited at best (I get the difference between AMOLED and LCD, etc), but I have a curious observation. So, I'm assuming were all familiar with the light bleed issue from the 2nd screen. It is my impression that the theory behind the light bleed is that the "back light" for the second screen is off to the left side of the 2nd screen. It would appear that this is the case as that's where the light bleed comes from, and also (on my phone at least) if there's a notification it's brighter towards theft side of the screen and you can see how the brightness tapers off towards the right side.
Here's where it gets curious, although I'm sure there's an explanation. After unlocking the bootloader and flashing TWRP I booted into recovery and noticed that the 2nd screen comes in TWRP. However you would think that TWRP would be full screen on the main screen, but it isn't. The 2nd screen completes the upper right part of the TWRP full screen, the only place it's not full is to the left of the 2nd screen where the front facing cameras are. It looks absolutely seamless, like there's not really a 2nd screen at all, it's obviously lit from the back and not the side. It was too bright and even all the way across to the right side of the second screen to be lit from the side like it is when the screen is off.
Is there a "side" back light and a main back light? Why does it look so perfect in TWRP, literally like it's all one screen? I'll try and take some pics later but if any of you have TWRP flashed check it out. IMO there's something fishy here, or maybe I'm just crazy.
Sent from my LG-H901 using Tapatalk

---

It really isn't a second screen, the phone would have costed maybe even double the price perhaps. One is thinking about how to keep try same resolution to be on par with the main screen, but what I think it is though in terms of it maybe being a special custom backlighting connected to an independent source along with software to then have the two screens one type of feel. I'm just giving my opinion, this phone I had to return and exchange because the notification bar backlight for to overwhelming and literally was day and nigh contrast on the strip of second screen. Now with this exchange I now have screen bleed under the ffcameras.

---

0dBu said:
Is there a "side" back light and a main back light? Why does it look so perfect in TWRP, literally like it's all one screen?
Click to expand...
Click to collapse
BINGO. There are two backlights. First is the normal backlight that lights up the entire display (there is no "second screen" - it's a single LCD panel). Then, there's the secondary backlight - a single white LED on the left edge of the "second screen." This single secondary backlight LED is injecting light through the left edge of the second screen and is not attached to the main backlight diffuser, which is why it lights the screen so unevenly. There are certain times when that secondary LED is on and when it is off. When it is on, it adds extra light near the left edge of the screen, which makes the notifications in that area brighter.
Try this. Turn on the Camera app and observe the buttons that appear on the second screen. Notice that the left-most (or bottom, if you hold it horizontally) button is NOT brighter at all? That's because the second backlight turns off when the camera app is running, and you only see the main screen backlight, which is even. Exit the camera app and you'll see the second backlight turn on and the bleed return. Open the camera app again and you'll see the bleed disappear, as the second backlight turns off.
Do another test. Hold the phone at an angle so the bleed from the second backlight is clearly visible, then go into the settings for the second screen, and turn it off while watching the left-most edge of the second screen - you'll see the "bleed" suddenly disappear, because the secondary backlight turns off (even though the main backlight is on). Turn the second screen back on while watching the left edge, and you'll see the bleed come back as the secondary backlight turns back on.
Yet another way to see it - power off the phone, then power it on while watching the left edge of the second screen. During initial boot, it will look perfectly even, no bleed, because the secondary backlight is off. But half-way through the boot process, the secondary backlight turns on, and you see "bleed."
Now, when the main screen is off, the ONLY thing lighting the second screen is the secondary backlight, so ALL you see is bleed (since the main backlight is off) which looks horrible.
The reason you don't see bleed at all in TWRP is because TWRP doesn't know that there is a second backlight and therefore it doesn't turn it on, since it doesn't know how.
To get rid of the "brighter left side" problem when the main screen is on, all LG has to do is issue a software update that turns off the secondary backlight when the main screen is on - I'm surprised they overlooked this obvious problem.
And here's the kicker - you know why you don't see the second screen bleed on the demo units in stores? Because the Retail Mode app turns the secondary backlight off, just like the camera app.

---

siraltus said:
BINGO. There are two backlights. First is the normal backlight that lights up the entire display (there is no "second screen" - it's a single LCD panel). Then, there's the secondary backlight - a single white LED on the left edge of the "second screen." This single secondary backlight LED is injecting light through the left edge of the second screen and is not attached to the main backlight diffuser, which is why it lights the screen so unevenly. There are certain times when that secondary LED is on and when it is off. When it is on, it adds extra light near the left edge of the screen, which makes the notifications in that area brighter.
Try this. Turn on the Camera app and observe the buttons that appear on the second screen. Notice that the left-most (or bottom, if you hold it horizontally) button is NOT brighter at all? That's because the second backlight turns off when the camera app is running, and you only see the main screen backlight, which is even. Exit the camera app and you'll see the second backlight turn on and the bleed return. Open the camera app again and you'll see the bleed disappear, as the second backlight turns off.
Do another test. Hold the phone at an angle so the bleed from the second backlight is clearly visible, then go into the settings for the second screen, and turn it off while watching the left-most edge of the second screen - you'll see the "bleed" suddenly disappear, because the secondary backlight turns off (even though the main backlight is on). Turn the second screen back on while watching the left edge, and you'll see the bleed come back as the secondary backlight turns back on.
Yet another way to see it - power off the phone, then power it on while watching the left edge of the second screen. During initial boot, it will look perfectly even, no bleed, because the secondary backlight is off. But half-way through the boot process, the secondary backlight turns on, and you see "bleed."
Now, when the main screen is off, the ONLY thing lighting the second screen is the secondary backlight, so ALL you see is bleed (since the main backlight is off) which looks horrible.
The reason you don't see bleed at all in TWRP is because TWRP doesn't know that there is a second backlight and therefore it doesn't turn it on, since it doesn't know how.
To get rid of the "brighter left side" problem when the main screen is on, all LG has to do is issue a software update that turns off the secondary backlight when the main screen is on - I'm surprised they overlooked this obvious problem.
And here's the kicker - you know why you don't see the second screen bleed on the demo units in stores? Because the Retail Mode app turns the secondary backlight off, just like the camera app.
Click to expand...
Click to collapse
Spot on!