Page 1 of 3 123 LastLast
Results 1 to 20 of 56
Like Tree7Likes
  1.    #1  
    I have 2 AT&T Pre3s, one I use as a spare battery charger and the other as my phone. One day as I was swapping batteries I noticed a red light that looks like an LED coming from my spare phone's proximity sensor area. I tried to take a picture of it but it turned off within 20 seconds and I had a hard time focusing on it. So I kept a camera handy to see if it would ever happen again.

    Just tonight, the phone I used did the same exact thing as I did a battery swap right when I went to power it up. So now I can confirm that this was not just an anomaly with the spare phone. So the only way to replicate this that I have seen is to insert a battery into the phone and power it up, and I have only seen this twice.

    Has anyone else noticed this? Can anyone speculate as to what this light is for? It would be pretty neat if there was some other LED we could use to access as another type of notification light. Here are the best pictures i could take in the time i had. In actuality, the light is not that bright. It looks like a little pinpoint light its not really bright and its not all that noticeable unless you happen to be looking.



    xandros9 likes this.
  2.    #2  
    Wow no one finds this odd at all?

    -- Sent from my Palm Pre3 using Forums
  3. #3  
    I find it very interesting. Haven't done a battery pull on my phone yet to see if I can replicate it.
  4. #4  
    It looks to me like an infrared light, like if you took a digital camera and looked at the end of a remote control while pressing a button on the remote. I don't know it that front facing camera uses IR for anything, or why you would have been able to see it with out a camera if that were the case though. And I tried replicating it with my Pre 3 with no luck... pretty interesting find.
  5. #5  
    I've also seen the red LED in the same situation, but not sure what it's for.
  6. #6  
    considering when it happens, and this is just a guess, but perhaps this is just part of a startup/diagnostic check for the proximity hardware... I mean a proximity detector has to emit something in order to measure the delay in bounce back/lack of bounce back necessary to detect the presence of an obstruction. It makes sense to use low or no visibility spectrums so people don't see the proximity detector at work.
    if it were a passive detector it wouldn't work in low-no night situations....can you imagine if your phone thought it was next to your head when you turn the lights out? Annoying.
    Palm Centro -> Palm Pre- -> HTC Evo 3D SPRINT
    iPhone 3G -> HP Veer Black -> HP Veer White AT&T
    Palm Pre 2 -> HP Veer Black -> HP Pre 3 (UK - Unlocked 8gb) AT&T
    HP Pre 3 (US - AT&T 16gb)
    HP TouchPad Black 1.2GHz 32GB
    HP TouchPad White 1.5GHz 64GB
    HP TouchPad Black 1.5GHz 32GB AT&T

    (You have no idea what I would do to get a TouchPad Go)

    Obviously I have a problem (see above). . .
    And it has nothing to do with more cowbell. . .
  7.    #7  
    I don't think the proximity sensor needs to emit any visible light for any purposes. But I do think that the light does indicate some sort of diagnostic check on startup perhaps not related to the proximity sensor. All webOS phones have proximity sensors and no one has ever reported this light coming on.

    I think it would be cool if the light came on to indicate that the front facing camera was in operation. And I think it would also be cool if the proximity sensor worked as well as it did in the Pre Plus and Pre2.
  8. #8  
    For what it's worth, I also tried a few of the interactive tests and thought that might show something. I even had a digital camera looking at it through the view finder to see if there was an IR signal I was missing and couldn't find it. I did the screen and proximity sensor test but nothing else.
  9.    #9  
    Yeah its odd. Its definitely not IR, you can see it with your own eyes. And both my phones did it so I am really intrigued.

    To be specific, the first time it happened was on my spare 3. I had it plugged in with no battery. I put a battery in it and walked away. The phone didn't sense I installed a battery and so I pressed and held the power button to power it up to charge and thats when the light came on, for approximately 20-30 seconds.

    Second time it happened, was on the phone I use, I shut the phone down at 30% to swap for a freshly charged battery. Pulled the battery, replaced it, turned the phone on and the light came on with the HP logo, again for 20-30 seconds.

    Both times it is worth noting I was indoors in low lighting conditions.
  10. #10  
    it's the infra red light, which is the proximity sensor. The infra-red light emits weak radiation and then a sensor detect whether or not it bounces back. If it does, your device won't turn on the screen during a call, as it means there is a reflector nearby.

    The camera you have taken pictures with is digital. Digital cameras can pick up infra-red light. Try holding down a button on your remote-control for your TV and look at the top through the camera, you should see a purple/red glow.

    Actually, you should be able to see a very feint red patch where this light is even without the camera, that's just the tiny part of the infra-red emitter which ventures in to the visible part of the electromagnetic spectrum when visible light is reflected off it. You say you can see the light properly without a camera. This may mean that your light is emitting light with higher energies and shorter wavelengths than I would expect, and so it passing over into the visible light part of the spectrum. This also explains the very purple picture you've taken with your camera, as high energy light is blue, red+blue=purple.

    Pardon the physics.
    Last edited by andyt95; 10/24/2011 at 10:33 AM.
    Nokia 1110 ---------> S-E J300i ---> HTC Touch ------> HTC Hero --------------> HP Pre 3

    Jimbode likes this.
  11.    #11  
    Quote Originally Posted by andyt95 View Post
    it's the infra red light, which is the proximity sensor. The infra-red light emits weak radiation and then a sensor detect whether or not it bounces back. If it does, your device won't turn on the screen during a call, as it means there is a reflector nearby.

    The camera you have taken pictures with is digital. Digital cameras can pick up infra-red light. Try holding down a button on your remote-control for your TV and look at the top through the camera, you should see a purple/red glow.

    Actually, you should be able to see a very feint red patch where this light is even without the camera, that's just the tiny part of the infra-red emitter which ventures in to the visible part of the electromagnetic spectrum when visible light is reflected off it. You say you can see the light properly without a camera. This may mean that your light is emitting light with higher energies and shorter wavelengths than I would expect, and so it passing over into the visible light part of the spectrum. This also explains the very purple picture you've taken with your camera, as high energy light is blue, red+blue=purple.

    Pardon the physics.
    Sorry but this light is definitely not infrared. It is very noticeable without a camera. Looking at the infrared light of the proximity sensor when active can only be seen with the camera and it is a very faint blink. This light is steady and quite noticeable with no camera. And as previously mentioned, I have never seen this on any other phone with a proximity sensor.
  12.    #12  
    Quote Originally Posted by andyt95 View Post
    I've told you why it might be noticeable. TRUST ME. it's infra-red.

    Read the whole of my post next time, before you reply.
    I repeatedly read the whole of your post before I replied. I am willing to entertain the idea that the light I so visibly saw with my own eyes was infrared. I also tried turning on the phone with the camera to see if the proximity sensor did anything that I couldn't normally see without a camera, and nothing at all. The only time I could see anything with the camera (aside from the two instances I saw it with my own eyes of course) was when I made a phone call with the phone to see the very faint blink. Wondering how come no other phone I have ever seen had the infrared proximity sensor light up so visibly.
  13.    #13  
    Well if that is the case the Pre3 must be made differently in that regard than any other phone, since three different Pre3s had the same thing happen. I am not trying to say you're wrong or anything. I was just wondering if for some reason they had an indiicator light in that area and if so what could its other uses be. No need to get all bent out of shape over it.

    Edit - you have at the very least enlightened me that an infrared transmitter can emit visible light.
  14. #14  
    Quote Originally Posted by vasekvi View Post
    Well if that is the case the Pre3 must be made differently in that regard than any other phone, since three different Pre3s had the same thing happen. I am not trying to say you're wrong or anything. I was just wondering if for some reason they had an indiicator light in that area and if so what could its other uses be. No need to get all bent out of shape over it.

    Edit - you have at the very least enlightened me that an infrared transmitter can emit visible light.
    @vasekvi Perhaps your eye has special ability to see infra red light. You may experiment it with other IR device.
    Palm III> Visor> Visorphone> Treo 180> 270> 600> 650> 680> Centro> HTC Tilt> BB-8310> Pixi-Plus> Pre 3
    Touchpad 16GB
  15. #15  
    I've seen this red light as well once on my veer. It was during reboot. Never saw it again.
  16.    #16  
    Quote Originally Posted by jmdesai View Post
    @vasekvi Perhaps your eye has special ability to see infra red light. You may experiment it with other IR device.
    Others have seen it too so there are more people with my special ability than just me

    -- Sent from my Palm Pre3 using Forums
  17. #17  
    Quote Originally Posted by somline View Post
    I've seen this red light as well once on my veer. It was during reboot. Never saw it again.
    I always see it during reboot.Very clear.
  18. #18  
    Quote Originally Posted by nathanail View Post
    I always see it during reboot.Very clear.
    me, too.
  19. excimer's Avatar
    Posts
    76 Posts
    Global Posts
    116 Global Posts
    #19  
    Fellas -

    I am an ophthalmologist working for industry (laser vision lasers). Infrared light is NOT visible by the human eye. Period. There is a near infrared part of the light spectrum that is closest to the vibrant visible red (710 to 750 nm) part of the visible spectrum but infrared light (NWIR near wavelength infrared, MWIR medium wavelength infrared and LWIR long wavelength infrared) is never visible to the human eye unaided. So... if you are human and if you are able to see it - it is not infrared. Just a fact.
  20. #20  
    Quote Originally Posted by Excimer View Post
    Fellas -

    I am an ophthalmologist working for industry (laser vision lasers). Infrared light is NOT visible by the human eye. Period. There is a near infrared part of the light spectrum that is closest to the vibrant visible red (710 to 750 nm) part of the visible spectrum but infrared light (NWIR near wavelength infrared, MWIR medium wavelength infrared and LWIR long wavelength infrared) is never visible to the human eye unaided. So... if you are human and if you are able to see it - it is not infrared. Just a fact.

    I've been wondering about this since the first day I got my Pre3.
    Glad enough of them are out now that other people have seen it too.

    Maybe we're not Human...

    webOS Developer
Page 1 of 3 123 LastLast

Tags for this Thread

Posting Permissions