OLED screens do emit light when showing black

[Guest AceOfSpades]

Ok I took some pics of my san francisco that I bought the other day in a dark room because I wasn't sure if it was LCD or OLED, I could see the screen glowing slightly, i.e in a dark room I could see the grey rectangle of the screen but I was told OLED emits NO light whatsoever. I've taken some pictures and the camera couldn't detect anything, even in night mode with a very long exposure. But I tweaked the pictures a bit (altered brightness to max and contrast to lowest) and you can see the outline of the screen.

So anyone who can see a slight glowing on their B05 san francisco you do have AMOLED, you just have very sensitive eyes :P

The second picture shows the blade next to a psp also showing black for comparison on how much I had to alter the picture to find anything ;)

[Guest fonix232]

The OLED screens CAN'T emit light when they are totally black. Why? Because it is the main design of the technology, if the color is black (#000000) then the light emitter diode is cut off, it DOES NOT emit light. So basically, you get a lot of leds, one per pixel (that means 480x800pcs of pixel, what is 384000 pcs of pixel), and they are controlled separately. So when switched off, the diode can't emit light, that's why it is so black. I have to say, you've been ripped off, badly. Take back the phone and tell them it isn't OLED!

[Guest Russell Crawford]

It looks like you've got an OLED screen, mine is OLED and the black levels are very good but in the dark I can still see a slight difference between the screen and the rest of the phone.

[Guest Surmoka]

The OLED screens CAN'T emit light when they are totally black. Why? Because it is the main design of the technology, if the color is black (#000000) then the light emitter diode is cut off, it DOES NOT emit light. So basically, you get a lot of leds, one per pixel (that means 480x800pcs of pixel, what is 384000 pcs of pixel), and they are controlled separately. So when switched off, the diode can't emit light, that's why it is so black. I have to say, you've been ripped off, badly. Take back the phone and tell them it isn't OLED!

AceOfSpades is right, the OLED panel DOES emit a very little amount of light even when black. As the panel is under current when the screen is turned on, and technology just isn't 100% perfect, a little dawning can be seen even at "turned out" pixels, albeit the light is of course a lot weaker than that of the TFT screen.

[Guest fonix232]

AceOfSpades is right, the OLED panel DOES emit a very little amount of light even when black. As the panel is under current when the screen is turned on, and technology just isn't 100% perfect, a little dawning can be seen even at "turned out" pixels, albeit the light is of course a lot weaker than that of the TFT screen.

That's weird, because it is in the declaration of the technology: the light-emitting diodes under the pentile matrix screen are switched off when they receive the 00 00 00 RGB color code. ANd the pentile color matrix can't emit light, right? ;)

Maybe ZTE built in a secondary background light to help the work of the OLED panel, and that's what causing the faint lighting!

[Guest Arr Too]

Just light bleeding into the case from the backlights on the buttons?

[Guest Surmoka]

That's weird, because it is in the declaration of the technology: the light-emitting diodes under the pentile matrix screen are switched off when they receive the 00 00 00 RGB color code. ANd the pentile color matrix can't emit light, right? ;)

Maybe ZTE built in a secondary background light to help the work of the OLED panel, and that's what causing the faint lighting!

I don't know the exact cause in this case, but the black OLEDs may even emit light because they are in a strong electromagnetic field and there is no perfect field separation. We are talking about a mobile phone here with a battery and electronics.

Plus, I've noticed that a dark grey digital clock displayed on my otherwise black screen depletes battery much faster than a screen turned off. SO it seems we have something of a "leakage" here.

Edited December 7, 2010 by Surmoka

[Guest AceOfSpades]

That's weird, because it is in the declaration of the technology: the light-emitting diodes under the pentile matrix screen are switched off when they receive the 00 00 00 RGB color code. ANd the pentile color matrix can't emit light, right? ;)

Maybe ZTE built in a secondary background light to help the work of the OLED panel, and that's what causing the faint lighting!

The technical explanation would be that the transistors allow a small current to pass through the pixel even when its supposed to be off, thats why it doesn't matter how high I set the brightness, the glow is still the same. You have to remember that transistors aren't perfect and even heat at room temperature generate a current through them. Also on wikipedia it says how OLED screens use 40% of the power of LCD screens when showing black, that implies the screen is still using power, otherwise it would be 0% of the power of LCD.

There is no backlight or the glowing would get brighter when I turn the brightness up.

I thought it could be light bleeding through from the buttons but even when those lights go out the glowing remains, also the glow is far too even for it to be that anyway.

If you have OLED test this out, you might not be able to see it straight away because it is quite dim but you should be able to see it in your peripheral vision.

EDIT

Just a paragraph I found on http://www.displaymate.com/Galaxy_S_ShootOut.htm It proves light is emitted by OLED although just a very low amount

2. Black Level Brightness: Less Than 0.005 cd/m2 – Outstanding

The Black Level is the closest approximation to true black that the display can produce. Almost all displays wind up producing a visible dark gray on-screen instead of true black. This is a major problem for LCDs. The glow reduces image contrast and screen readability and can be distracting or even annoying in dark environments. It ruins the dark end of the display’s intensity/gray scale and washes out colors in the image. But note that in bright ambient lighting the Black Level is irrelevant because reflections off the screen dominate the screen background brightness. OLED is an emissive technology, so the Galaxy S is able to produce very close to true black, which is absolutely stunning in dark ambient lighting. In fact, the Black Luminance was so low that the CS-200 was unable to measure it, so we report it as less than 0.005 cd/m2, which means it is nearly invisible to the eye even in the dark.

Edited December 7, 2010 by AceOfSpades

[Guest BigBearMDC]

It is nearly impossible that the OLED screen emits light when turned off. Even if the flows a small current - and it in fact does - there's no way that it could have enough energy to make the LEDs shine. Furthermore each LED needs a minimum voltage of 0,3 to 0,7 volts, below this level diodes do not conduct. Another thing is that the different colours of LEDs need different currents to shine. So even if there would flow some current - regardless of all the facts I mentioned - the screen wouldn't glow white but pink or blue (the green LEDs need more power than the blue ones and the red ones need less power than the blue ones). So I don't know what glows, I never recongized it either, but its pretty sure not the OLED screen. If it is the screen ZTE messed something up.

Best regards,

BB

[Guest fonix232]

I don't know the exact cause in this case, but the black OLEDs may even emit light because they are in a strong electromagnetic field and there is no perfect field separation. We are talking about a mobile phone here with a battery and electronics.

Plus, I've noticed that a dark grey digital clock displayed on my otherwise black screen depletes battery much faster than a screen turned off. SO it seems we have something of a "leakage" here.

Just as BigBear said, it is some kind of ZTE bug. I've never noticed such happening with the Galaxy S.

Szóval tuti hogy a ZTE cseszett el valamit (megint, lásd magyar kijelzők túlfeszültsége, akkor a fordítottan behelyezett kijelző, és a hibás forráskód), de lehet csak szoftveres probléma!

[Guest AceOfSpades]

Just as BigBear said, it is some kind of ZTE bug. I've never noticed such happening with the Galaxy S.

Szóval tuti hogy a ZTE cseszett el valamit (megint, lásd magyar kijelzők túlfeszültsége, akkor a fordítottan behelyezett kijelző, és a hibás forráskód), de lehet csak szoftveres probléma!

read the section on black level on this site http://www.displaymate.com/Galaxy_S_ShootOut.htm

They mention there is some light emitted but it is almost undectectable for the light measuring instument and thus nearly invisible to the eye.

It is nearly impossible that the OLED screen emits light when turned off. Even if the flows a small current - and it in fact does - there's no way that it could have enough energy to make the LEDs shine. Furthermore each LED needs a minimum voltage of 0,3 to 0,7 volts, below this level diodes do not conduct. Another thing is that the different colours of LEDs need different currents to shine. So even if there would flow some current - regardless of all the facts I mentioned - the screen wouldn't glow white but pink or blue (the green LEDs need more power than the blue ones and the red ones need less power than the blue ones). So I don't know what glows, I never recongized it either, but its pretty sure not the OLED screen. If it is the screen ZTE messed something up.

Best regards,

BB

I see your point about the leds needing a certain voltage, I don't know exactly how the screen works but power is still being dissipated in the screen somehow and i guess this is what causes the glow. The light is detecable as you can see from my camera shot, although only just. Its not even just zte or my screen in particular, the galaxy s and nexus one in that link - which seems very scientific, also both produce a tiny amount of light when showing black. I guess its just imperfections in the technology.

Also green is the most efficient led, then red then blue is by far the least efficient

[Guest markusj]

Theoretically, there is no difference between the turned off and the full black screen, that's why it's LED.

If it would really glow in the dark, it would eat your battery even when turned off.

Maybe the LEDs of the buttons aren't separated from the screen, and somehow you see their light.

[Guest Mr.Modaco-YeahBaby!]

Seriously, some people have enormous problems...

Edited December 7, 2010 by Mr.Modaco-YeahBaby!

[Guest puj]

This also happens on other phones with oled screens, there is a discussion about this here: http://forum.xda-developers.com/showthread.php?t=743940.

It can be seen clearly if you view a black image full screen in a dark room. there is a glow which disappears when the power button is pressed to lock the screen.

[Guest abdidas]

This also happens on other phones with oled screens, there is a discussion about this here: http://forum.xda-developers.com/showthread.php?t=743940.

It can be seen clearly if you view a black image full screen in a dark room. there is a glow which disappears when the power button is pressed to lock the screen.

This is true, I was told just because of this my phone was LCD but it clearly wasn't even the build no. ended with B05 and it was before the white one came out.

Anyways I now got a replacement and even though it is B08 I am pretty sure it is still OLED, I get pink hue on white and grey when on lower brightness and the black is black, still getting alittle backlight but I doubt it is the same as LCD levels.

any otherwise to know what screen you have?

[Guest goatee]

Get a magnifying glass - if it's OLED, you can see sub-pixel rendering - e.g. http://gizmodo.com/5502866/the-nexus-ones-...s-the-subpixels

This is true, I was told just because of this my phone was LCD but it clearly wasn't even the build no. ended with B05 and it was before the white one came out.

Anyways I now got a replacement and even though it is B08 I am pretty sure it is still OLED, I get pink hue on white and grey when on lower brightness and the black is black, still getting alittle backlight but I doubt it is the same as LCD levels.

any otherwise to know what screen you have?

[Guest wtel]

My Blade does glow when displaying a dark image. It's quite obvious, though not that strong when compared with LCD.

[Guest zed2012]

I have noticed the same problem - well its not a problem and you cant even notice it to be honest expect in an absolute dark room and after a minute or two to let your eyes adjust. I have only noticed it when I started using Noled - at night.

The pixels are not powered for sure. I think its to do with the optics the screen is small distance away from the front glass/touch screen so the light coming off the pixels that are on is just 'bouncing' about.

I think its called internal refraction or something ;)

Just a guess

[Guest userof2]

Don't forget it is a slightly reflective surface, and your room isn't in absolute perfect darkness. Considering how much the photo has been adjusted, it's probably just a slight reflection.

[Guest AceOfSpades]

Theoretically, there is no difference between the turned off and the full black screen, that's why it's LED.

If it would really glow in the dark, it would eat your battery even when turned off.

Maybe the LEDs of the buttons aren't separated from the screen, and somehow you see their light.

Thats the thing it does still drain power, as I have posted before it is quoted as using 40% of the energy of LCD when displaying black Which obviously means that some power is being drained and this is what causes the glow.

I've already said that even when the buttons are off the glow remains and as this happens on all other OLED displays its not a fault of the phone, its the general screen technology.

I and several others have provided plentiful evidence that the screen does in fact glow, the intensity is so low that I guess it is invisible to some people and certainly cameras.

Just think, a CRT is also apparantly capable of complete black but if you turn the lights out there is also a glow. Either the flourencency of the screen, magnetic/electric field or a quantum effect causes the emission on the oled screen, whatever it is its not going to be easy to explain in laymens terms.

This thread is just to inform people that even if they see a very small glow they do in fact have the OLED screen, the "true black" is something that companies have come up with as a marketing term vs LCD and yes, it is invisible when anything else is onscreen and even takes ~10 seconds to see in the dark because its so dim, their claims however should be taken with a pinch of salt, the term "unlimited internet" bares a somewhat exaggerated resemblence.

Edited December 8, 2010 by AceOfSpades

[Guest BEKO-86]

Just tested my OLED,

Absolutly no light, zilch.