Why do LCD screens need a backlight? (seriously)

Bear with me on this, I'm well aware that most LCDs have backlights. But what if, they DIDN'T?

I spend long hours in front of a screen and I hate the concept of staring into a lightbulb all the time and my eyes getting sore.

I need to get a new lcd (some sort of IPS that doesn't cost a fortune) soon, but no matter what I'll get, I'll still be looking at a damn light.

How come you can read on a kindle w/o a backlight but there aren't any monitors like that? I mean, ideally, a screen should be like a book or any other object in real life. Just for curiosity's sake, does anyone know of any new monitor concepts?

Also, http://www.indiaonrent.com/view/l/laptop-transparent-monitor.html hah!

Spectraljump

Posted 2011-01-16T17:25:50.470

Reputation: 608

I suspect that most people don't view it as staring into a light – try using white on black if it really hurts your eyes. – Rich Bradshaw – 2011-01-23T16:21:45.323

I use this http://www.charcoaldesign.co.uk/shades and there's probably similar for Windows.

– tobylane – 2011-01-23T17:12:56.857

Answers

Kindles and other eBook readers do not have LCD screens. They are eInk displays and there is a significant difference.

LCDs come in 3 varieties: Transmissive (light goes through, Reflective (light bounces), and Transflective (some light pass, some bounces). Only transmissive has good ability to reproduce colors. Transflective has some ability, but not much. Reflective, like pocket calculators and similar devices have basically no ability to produce appreciable color.

Here's an example of what it looks like when the backlight burns out. As you can see, it's incredibly hard to see the picture at all. If you think you have eye strain from looking at a light source, it pales in comparison to trying to read one of these: burnt out LCD backlight

If you are really adverse to looking at a bright light, try turning down the brightness. It's not the same as an eInk display, but I don't believe those are available as general purpose displays yet, and have an refresh time measuring most of a second (not 5 thousands of a second like a "typical" LCD).

Chris S

Posted 2011-01-16T17:25:50.470

Reputation: 5 907

Thanks for the response mate! I was wondering why common LCD's do not reflect light (but you cleared that up). I can turn off my laptop's backlight and it looks the same as in your photo. I was thinking, maybe allow the light to go towards the screen (like a lamp lighting a book) instead of the opposite way. But that's probably not an option. Anyway, thanks for listing the categories. – Spectraljump – 2011-01-17T07:41:20.987

If you want to go monochrome then there are plenty of passive display devices available (although the price varies widely depending on what you're looking for). But indoor ambient lighting, weak as it is, can't illuminate a triple layer of LCD color brightly enough for it to be visible, and color ePaper is still ridiculously hard to get a hold of.

Ignacio Vazquez-Abrams

Posted 2011-01-16T17:25:50.470

Reputation: 100 516

Interesting. Didn't know about the ePaper (has slow refresh rate I noticed :P). Manufacturers should really think about and try to solve the whole staring into a lightbulb thing. It seems that a transparent laptop screen works well-ish with ambient light. I'll probably try to hack my monitor with a hammer once I get a new one. – Spectraljump – 2011-01-16T20:52:33.460

@Tudor: AFAIK only one manufacturer has made a transparent laptop screen, and it was intended for use with an overheard projector rather than ambient light. – Ignacio Vazquez-Abrams – 2011-01-16T21:19:58.377

http://www.youtube.com/watch?v=yiPEoRzpyus&feature=related Samsung OLED. Maybe it's jut me or the video(s), but I can notice the reduced number of colours / inaccuracy on that display. – Spectraljump – 2011-01-17T08:11:57.720

The newer LCD screens with full field LED back-lights will dim the LEDs on those parts of a display with dark regions, as in a movie's night scene. This technology is used for TVs at this point but if demand is high enough there is no reason why it can not be used for computer displays.

Cirric

Posted 2011-01-16T17:25:50.470

Reputation: 1