1. MacHouse83's Avatar
    First off I would like to say I love this phone, I was skeptical coming from my Nexus 4 but I'm glad I made the upgrade.

    But I had a small issue today... I was listening to music on my phone and use the Knock Knock feature to lock my phone, I then noticed that the screen turned back on immediately without me touching it and then started to flicker. So I locked it again this time using the power button and it did the same thing with the flickering like it was constantly locking and unlocking itself.

    I finally decided to turn off the Knock Knock feature and it didn't happen after that... I'm wondering if it could be the screen protector i have messing with the sensitivity of the screen or just something funky with the feature?

    Let me know if anyone has experienced this!
    09-25-2013 11:14 AM
  2. NevetsDrassel's Avatar
    First off I would like to say I love this phone, I was skeptical coming from my Nexus 4 but I'm glad I made the upgrade.

    But I had a small issue today... I was listening to music on my phone and use the Knock Knock feature to lock my phone, I then noticed that the screen turned back on immediately without me touching it and then started to flicker. So I locked it again this time using the power button and it did the same thing with the flickering like it was constantly locking and unlocking itself.

    I finally decided to turn off the Knock Knock feature and it didn't happen after that... I'm wondering if it could be the screen protector i have messing with the sensitivity of the screen or just something funky with the feature?

    Let me know if anyone has experienced this!
    Maybe it is the music app that is not allowing the phone to go to the sleep mode. Check the permissions on the music app. I am new to this game but I do see that some of the apps will not allow the phone to go into sleep/stand by mode when they are running.

    You also might want to reset the Motion Sensor Calibration under Settings:Gestures:Motion sensor calibration.

    I have a theory that the reason that some people are having problems with the Knock Knock feature is that the phone needs to have the Motion Sensor Calibrated, but not only that, also how the phone is sitting in three dimensional space when it is calibrated. By this I mean that it is recommended that you place the phone lying down on a non moving surface when you calibrate it, but I am trying different phone positions when I calibrate it to see if there is a difference in the sensitivity of the sensor. But this assumes that the Knock Knock feature is based upon the sensor movement in three dimensional space instead of some other hardware component that resides under the screen.

    For my next test, I am going to calibrate the phone while the phone is sitting in the 45 degree upright position instead of flat on its back. I have calibrated the sensor several times and have noticed that there is a difference on how the Knock Knock feature reacts based on the calibration.
    MacHouse83 likes this.
    09-25-2013 05:01 PM
  3. JayWill's Avatar
    My current theory is that Knock On issues have something to do with the proximity sensor. Ever try to knock on your phone with your right hand when you're holding it upside down? It doesn't work, because the proximity sensor is picking up your hand. This feature is certainly to prevent turning on your screen when your device is in a bag or pocket. So it's possible that some screen protectors or maybe grease/smudges can cause issues with the sensor thus effecting the Knock feature. It's also possible that there are deep sleep issues with the sensor. In other words, the screen registers the two taps but it takes too long for the sensor to "wake up" and start listening, causing Knock-On to fail. Or something like that ... maybe.

    P.S. - You may be asking who in their right mind would try to Knock their phone on when it's upside down. Well, me for one, when in bed and grabbing my phone in the dark and not feeling for the buttons first. I've done it a lot actually.
    MacHouse83 likes this.
    09-25-2013 05:59 PM
  4. MacHouse83's Avatar
    Maybe it is the music app that is not allowing the phone to go to the sleep mode. Check the permissions on the music app. I am new to this game but I do see that some of the apps will not allow the phone to go into sleep/stand by mode when they are running.

    You also might want to reset the Motion Sensor Calibration under Settings:Gestures:Motion sensor calibration.

    I have a theory that the reason that some people are having problems with the Knock Knock feature is that the phone needs to have the Motion Sensor Calibrated, but not only that, also how the phone is sitting in three dimensional space when it is calibrated. By this I mean that it is recommended that you place the phone lying down on a non moving surface when you calibrate it, but I am trying different phone positions when I calibrate it to see if there is a difference in the sensitivity of the sensor. But this assumes that the Knock Knock feature is based upon the sensor movement in three dimensional space instead of some other hardware component that resides under the screen.

    For my next test, I am going to calibrate the phone while the phone is sitting in the 45 degree upright position instead of flat on its back. I have calibrated the sensor several times and have noticed that there is a difference on how the Knock Knock feature reacts based on the calibration.
    I will try that, I forgot to include that I do have Nova Launcher on and whille Knock On won't allow you to lock with the full screen you can still lock on the notification bar. I also have a Body Glove case on my phone so I was thinking maybe it was because the bezels are so thin it could mess with the sensors.

    But I went to stock LG UI yesterday and used for awhile then went back to Nova today and no problems... So maybe it was a glitch on my phone.

    I'll keep the advice handy though!
    09-26-2013 03:03 PM
  5. brick58's Avatar
    I am having a problem with my screen flickering while playing a game and everything else, it's not bad right now but will it get worse? this is day 2 of having it and I love it otherwise…how do you turn off knock knock, do you have to have that on?
    12-12-2013 05:26 PM
  6. biorockr's Avatar
    I am facing the same problem...and not so frequently but it does occur in a few days....I don't think it ever happened to me while listening to music.....but whenever it happened I had received notifications from my Google Hangout and local carrier SMS app "Messaging"....for instance, it so happened that i got a text from a friend and i got both hangout and Messaging notifications...so the routine started...."double tap" --> pattern unlock--> and checked the message in my hangout...then i did the usual double tap and closed it...but the screen wont turn off...i double tap again....screen pops on again....i use the back button....still the screen wont turn off...frustrated i just keep the phone with screen ON on the table....but then the screen weirdly starts flickering...I open the pattern unlock and check the notifications...there is still that notification of "Messaging" on from the text i received from my friend...I just sweep it out of the screen expecting that the notification might go....but NO...its still there...I try to sweep the notification off again but it just returned...so finally i tap on it to see the same text again....close the text...and now the notification is gone...i continue to double tap...and lo and behold....the screen goes OFF as usual...no problems at all....and my LG G2 is awesome again \m/
    Moral: Google Hangout has messed with your normal SMS app "Messaging" and they wont let you turn off the screen until you have checked them both...(this at least works in my device)
    Let me know if this solves your problem.
    PS- I too have Nova Launcher...maybe that might be the real devil...
    12-31-2013 12:09 AM
  7. Cindy Espiritu's Avatar
    I've got the same problem. but as i tried to troubleshoot it, 2 things worked.
    #1 clear all recent tasks in task manager.
    #2 do not leave notification unread.

    I was troubled because the flickering caused me to recharge my g2 twice on the same day.
    It caused my G2 to become really hot. i became cautious that my screen doesn't stay awake for some time.
    observing my battery setting, screen got the most percentage consuming my battery.
    01-30-2014 02:53 AM
  8. Shweta Prasad's Avatar
    Today I have also faced the same issue. I put knock-knock feature off after that the flicker issue is gone.
    09-10-2014 12:09 PM

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