Difference backlight and brightness?

[caphair]

I'm wondering how the brightness works on LCD tvs. Is is that more of each pixel is exposed?

[mariushm]

Re: Difference backlight and brightness?

The actual LCD is like a sheet of glass, transparent.

When a pixel needs to be white all three sub pixels (red, green and blue sub-pixels) are completely transparent and let the light from behind this glass go through. When you want a black pixel, all three sub-pixels are turned on completely so they're blocking 100% of the light.
Behind the LCD, there's several thin sheets of material that have purpose of spreading (diffusing) the light coming from individual leds and spreading it across the whole lcd screen. Then there's the individual leds spread all across the back side.
With computer monitors, sometimes the leds are on the edges of the screen, but with large tvs they're often all across the back.
The TV or monitor can then adjust how much energy is sent to the LEDs to adjust the overall brightness.
That's the most basic stuff, monitors and TVs have several other tricks like turning on and off individual pixels to have a finer brightness adjustment, or better contrast.

You can see here the insides of a lcd tv : https://www.youtube.com/watch?v=hh3z_dkkcUM
It's a repair video but if you're not interested in the diagnosis, you can skip to around 10:00 where he starts to take it apart and then you'll see the insides. On this one the leds are on the edge of the screen.

In this other repair video, the leds are all over the back of the tv , skip to around 5:00 if you're impatient : https://www.youtube.com/watch?v=Bf5T2wwtydY

[caphair]

Re: Difference backlight and brightness?

Ok but how is brightness adjusted as oppose to the backlight adustment?

They're both an option in the menu

[stj]

Re: Difference backlight and brightness?

by ajusting how translucent each pixel is.

[caphair]

Re: Difference backlight and brightness?

by ajusting how translucent each pixel is.

Cool thanks that's what I was thinking