# Laptop backlights are LED, but contain mercury?

**URL:** <https://boards.straightdope.com/t/laptop-backlights-are-led-but-contain-mercury/811591>\
**Category:** Factual Questions\
**Created:** [April 1, 2018, 6:21pm UTC](https://boards.straightdope.com/t/laptop-backlights-are-led-but-contain-mercury/811591 "2018-04-01T18:21:27Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Velocity](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/velocity/32/18006_2.png) [@Velocity](https://boards.straightdope.com/u/Velocity)\
**Post date:** [April 1, 2018, 6:21pm UTC](https://boards.straightdope.com/t/laptop-backlights-are-led-but-contain-mercury/811591/1 "2018-04-01T18:21:27Z")

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This one was a bit confusing to me - (Dell Latitude E5450, for what it’s worth) - apparently laptop screen backlights are LEDs these days, but LEDs don’t contain mercury - but there are warnings online about laptop backlights containing mercury? Did they used to be illuminated by small flourescent lamps or something?

And the LCD screens themselves don’t have mercury?

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**Author:** ![Dewey\_Finn](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dewey_finn/32/4222_2.png) [@Dewey\_Finn](https://boards.straightdope.com/u/Dewey_Finn)\
**Post date:** [April 1, 2018, 6:28pm UTC](https://boards.straightdope.com/t/laptop-backlights-are-led-but-contain-mercury/811591/2 "2018-04-01T18:28:24Z")

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> [@Velocity](#):
>
> there are warnings online about laptop backlights containing mercury? Did they used to be illuminated by small flourescent lamps or something?

Yes. From [Wikipedia](https://en.wikipedia.org/wiki/Backlight):  
"The light source can be made up of:

[ul]  
[li]Light-emitting diodes (LEDs)[/li][li]An electroluminescent panel (ELP)[/li][li]Cold cathode fluorescent lamps (CCFLs)[/li][li]Hot cathode fluorescent lamps (HCFLs)[/li][li]External electrode fluorescent lamps (EEFLs)[/li][li]Formerly, incandescent lightbulbs[/li][/ul]"

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**Author:** ![Velocity](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/velocity/32/18006_2.png) [@Velocity](https://boards.straightdope.com/u/Velocity)\
**Post date:** [April 1, 2018, 6:35pm UTC](https://boards.straightdope.com/t/laptop-backlights-are-led-but-contain-mercury/811591/3 "2018-04-01T18:35:10Z")

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> [@Dewey\_Finn](#):
>
> Yes. From [Wikipedia](https://en.wikipedia.org/wiki/Backlight):  
> "The light source can be made up of:
> 
> [ul]  
> [li]Light-emitting diodes (LEDs)[/li][li]An electroluminescent panel (ELP)[/li][li]Cold cathode fluorescent lamps (CCFLs)[/li][li]Hot cathode fluorescent lamps (HCFLs)[/li][li]External electrode fluorescent lamps (EEFLs)[/li][li]Formerly, incandescent lightbulbs[/li][/ul]"

OK, thanks. But out of all these, only fluorescent lamps contain mercury?

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**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\
**Post date:** [April 2, 2018, 3:11am UTC](https://boards.straightdope.com/t/laptop-backlights-are-led-but-contain-mercury/811591/4 "2018-04-02T03:11:46Z")

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Correct.