topic Re: Constant red light on the front side of the phone in XZ Series

Constant red light on the front side of the phone

Sailor1 — Mon, 24 Oct 2016 08:25:21 GMT

I bought this phone 2 days ago .. I'm noticing there is a constant red light right side of the Sony logo (in the sensor area i suppose). No I'm not talking about the led notification light. Can anyone tell me what's wrong with my phone?

Constant red light on the front side of the phone

Sailor1 — Mon, 24 Oct 2016 09:57:45 GMT

It's in one of the proximity sensors... Not sure why it's always on

Re: Constant red light on the front side of the phone

_alexdon_ — Wed, 26 Oct 2016 10:45:24 GMT

That's because you have automatic brightness enabled.

Re: Constant red light on the front side of the phone

Sailor1 — Wed, 26 Oct 2016 10:49:38 GMT

Yeah i just figured... I never noticed in any of my previous phones that's why i was confused

Re: Constant red light on the front side of the phone

_alexdon_ — Wed, 26 Oct 2016 10:54:05 GMT

This is a new feature on the x generation and makes the sensor really snappy, adjusting brightness on the go and really efficiently.

Re: Constant red light on the front side of the phone

Sailor1 — Wed, 26 Oct 2016 10:56:00 GMT

Thanks for the info Alex... My last xperia was Z... N then i switched to Moto .. Now finally back to Sony again ...

Re: Constant red light on the front side of the phone

_alexdon_ — Wed, 26 Oct 2016 10:58:13 GMT

Good to have you back with Sony! I hope you enjoy the device.

Re: Constant red light on the front side of the phone

Sailor1 — Wed, 26 Oct 2016 11:02:18 GMT

Really enjoying xz.. Read some good reviews as well... My only complain is with the battery... Sony was a beast in this department z3 is still the battery king... Xz feels like a step back

Re: Constant red light on the front side of the phone

Sunking1011 — Wed, 26 Oct 2016 11:09:26 GMT

Yeah the battery life is lousy. I get more out of my 2010 iPhone 4 which is still on the original battery.
I'm giving my XZ two full charges a day and that isn't going to make the non-removable battery last very long.

Re: Constant red light on the front side of the phone

_alexdon_ — Wed, 26 Oct 2016 11:13:38 GMT

Please don't go offtopic here, there are other threads on battery life.

Red light on top right of phone

Bellatrikz — Sat, 26 Nov 2016 06:48:52 GMT

Guys just got my xz, funny thing is got a dim red light on the top right side of it, next to the ear speaker on the right... Won't seem to go of unless the screen is closed

Re: Red light on top right of phone

adamlee2014 — Sat, 26 Nov 2016 07:21:51 GMT

This has already been discussed in another topic. Do you have adaptive brightness turned on under display settings? Try turning it off and the light will then go off.

Re: Red light on top right of phone

Korben-Dallas — Sat, 26 Nov 2016 07:31:51 GMT

@92 wrote:
This has already been discussed in another topic. Do you have adaptive brightness turned on under display settings? Try turning it off and the light will then go off.

Indeed, this has already been discussed. However, the conclusions made in those previous discussions (brightness sensor?) strike me as highly illogical. Why would a brightness sensor need to emit its own red light?

And no, disabling adaptive brightness has no effect on this light - it does not go off if you turn off adaptive brightness.

My guess would be that this is an IR LED providing illumination for an IR proximity sensor. A portion of the spectrum it emits is visible as dim red light. And it has nothing to do with adaptive brightness at all.

Re: Constant red light on the front side of the phone

Sunking1011 — Sat, 26 Nov 2016 09:56:03 GMT

It's so the phone can detect when you put it against your ear and thus switch the screen off. All phones have this sensor, some are just cranked up a bit more and become visible. My old, old iPhone 4 has a visible red proximity sensor and did from brand new.

Re: Constant red light on the front side of the phone

Bellatrikz — Sat, 26 Nov 2016 14:22:28 GMT

OK so I already figured that out with the adaptive display so now what do I do in the sun, any patch solution

Re: Constant red light on the front side of the phone

adamlee2014 — Sat, 26 Nov 2016 15:26:11 GMT

When I turn auto brightness off the light also goes off. Enable auto brightness and light comes back on. So I would say it's the auto brightness causing the red light. Confirmed on my XPERIA XZ

Re: Constant red light on the front side of the phone

Korben-Dallas — Sat, 26 Nov 2016 16:40:06 GMT

@92 wrote:
When I turn auto brightness off the light also goes off. Enable auto brightness and light comes back on. So I would say it's the auto brightness causing the red light. Confirmed on my XPERIA XZ

Now, start a telephone call and you will see that the red light comes on again, regardless of your auto brightness setting. In addition to that, even with auto brightness tuned off, the red light sometimes comes on intermittently for no apparent reason.

Ambient light sensor and proximity sensor in Xperia XZ is the same physical device. I.e. it is the same sensor that serves two functions. Ambient light measurement is a passive function: it does not need and additional illumination by any "red light". Proximity detection, on the other hand, is an active function: it works by detecting IR light emitted by an additional IR diode and reflected by user's skin back into the sensor. This IR illuminator diode is exactly what you see as dim red light.

It looks like Xperia XZ cannot power-manage these two functions independently, meaning that once you enable auto brightness, the entere sensor gets powered up, including the IR illuminator (even if the latter is completely unnecessary).

That's all there is to it.

So, again: the dim red light that you see is a part of proximity sensing function. The fact that it appears to be affected by auto brightness setting is just a purely "parasitic" connection, a quirk of Xperia XZ hardware. (I wonder what's the impact on battery life from this.)

Re: Constant red light on the front side of the phone

Lord_viridis — Tue, 29 Nov 2016 08:14:41 GMT

It did exactly the same with X and has such a minute effect on battery it's not worth worrying about

Red light proximity sensor

Eileenstorm — Tue, 06 Dec 2016 09:23:59 GMT

I woke up this morning and found a steady red light coming from the proximity sensor which I don't think it's normal. At least I didn't realised before... Anyone else with this problem?

Re: Constant red light on the front side of the phone

100rabh — Tue, 06 Dec 2016 10:51:34 GMT

It's just the proximity sensor.. Don't worry it's normal