To Nokia, ref. Lumia 920

JDB (Employee) 10 years ago updated by jimmyjjohn 8 years ago 6

Dear Nokia,

With the latest 920 ultra-sensitive screen, objects rubbing will be interpreted as touch. That being, if power button is accidentally pressed while inside pocket/bag, screen lights up, pants/objects will continuously touch the screen, PREVENTING the phone to standby  battery drain.

This is how WP lockscreen behaves today(though capacitive screens reduce the occurrence). I don't know whether WP8 or Nokia ROMs will change this behavior(resetting timeout upon every touch while locked, even if proximity detected), else the 920 would potentially become a battery killer.

Hope you are already aware and on top of this.


JDB Pocketware 

[Also posted on Nokia's Facebook]

Edit: As this expands across forums and blogs, some people are perceiving us as trolls, the bad guys. It is totally the opposite: we love Windows Phone and Nokia is the best hardware for us. Our intention is to anticipate a possible potential issue so it can be fixed on time by either Nokia or Windows Phone OS, if it was the case. Also please note this is pure theory/speculation, we are not affirming.


The issue explained/illustrated in detail:

Nature of Windows Phone buttons
Pressing either the power button or the camera button will cause the device screen to turn on, even when the proximity sensor detects proximity.

The lockscreen behavior
Upon power on, screen lights up and shows the lockscreen (or camera), which runs a timeout to auto power off the device if screen is not touched in X seconds.

But if screen is touched, the timeout counter is restarted, so continuous touching could lead into a loop, the "death loop" which won't let the device to power off (standby) and will consume battery life.

New touchscreen technology
The Nokia Lumia 920 comes with a touchscreen that reacts to touch from pretty much any material such as metal or clothes. This can be dangerous.

So here is a theory 
When the phone is inside a pocket or bag it can be touched by other objects. These objects can press buttons and can touch/rub the screen. This will initiate the "death loop" for who knows how much time, could be minutes or hours, depends on how active the user is since body movement will produce friction between objects/clothes and touchscreen:

The "death loop" will drain battery and battery is precious.


Should be simple: screen must not power on if the proximity sensor detects proximity. Current version of Windows Phone does not take care of this. The big question is: will Windows Phone 8 take care of this? Is the Lumia 920 a potential battery drainer?

Steps for testing this (if anyone got a 920 in his hands):

1. Set lockscreen timeout to 30 secs

2. Cover the proximity sensor (upper area of the phone)
3. Power off / Power on
4. Repeatedly touch the lock screen with any object during 30 seconds (say once every 5 secs or so)

After 30 seconds, will it power OFF? or will continue ON forever?

The firmware has been configured to avoid accidental activation of the display. In testing this has not proven to be an issue or to cause unwanted battery drainage.

The firmware requires a ‘landing event’ to move into active mode and without a repeat of that landing event will return into sleep mode.


Thanks Tom. So "landing event" means contact over the screen, right? Sounds good (only risk could be that clothes rubbing could unlock, since WP lockscreen unlocks by just half inch swiping).

Wondering, won't the proximity sensor prevent the power button to activate the screen(if proximity detected)?



My Lumia 920 DID accidentally unlock in my pocket. I made sure its display was off before putting it into pocket. After a while my pocket was feeling warm and only then I noticed my 920 was unlocked and its display was on. I have always set Touch sensitivity to "Normal" instead of "High".