Why do computer screens project black when they can just project nothing?


If your monitor is off it projects nothing so why can’t they just project nothing for black?

In: 11

that’s exactly what they do. There are two types of screens: LED and LCD. The first one produces color by turning on very small lamps for every pixel of the screen, the brighter the color the brighter it shines. For example red will be full red lamp, green lamp off and blue too, while black would be all off.

For LCD screens it’s a bit more complicated. Basically the screen is illuminated from the back by a single lamp, and every color pixel is a liquid crystal that “opens or closes” more depending on the amount of light that should go through. For black it doesn’t allow for any light to pass through, so it’s just as if it were off. But obviously in this case the main light can’t be turned off or everything else on the screen would be black too.

Most modern monitors use a white backlight, and then block certain colors to form the display. For black, the monitor blocks as much light as possible. One notable exception is OLED display technology, which uses tiny individual lights to form the display. These monitors can just leave the LEDs off to form black, but they are far from the most dominant display technology.

Hope that helps.

There are to main parts to your normal display: the LED screen and the backlight. The LEDs are what provide all the pixels and colors for your image. The backlight is what illuminates them so the user can actually see them. In most monitors and TVs, backlights are always on and cover the entire screen all at once. This is why, even if the pixels are black and turned off, you see illumination.

Some newer monitors have localized illumation zones. The more zones, the more granular the illumination, and black effect. Some companies are even working on each pixel illuminating for itself, which results in a drastic change of perception of blacks for the user.

Some do, some don’t. There are 2 types of screens (nowadays at least):

**LCD/LED:** Each pixel is split into a red, green, and blue sub-pixel. There is a light behind the screen (backlight) that shines through the pixels, and each sub-pixel acts like a filter that only allows a certain color of light through. The amount of light that each sub-pixel lets through can be controlled electronically. Therefore we start with WHITE light, and based on the amount of each color we filter out we end up with our final color for that pixel. These filters aren’t perfect, so even when they’re *trying* to block 100% of the light (black) they’re still accidentally letting some through.

Both LCD and LED both use LCDs to filter the light, the only difference is that traditional LCD screens use fluorescent lights for a backlight, and LEDs use LED lights for the backlight allowing them to be thinner.

**OLED/AMOLED**: Instead of starting with white light and filtering out the colors we want like LCD/LEDs do, each sub-pixel on an OLED/AMOLED screen *is it’s own light!* Not only can these screens be incredibly thin because we don’t have that pesky backlight anymore, but it also means we can choose to turn a pixel completely off, getting pure black.

In the old days, we also had plasma screens, which was an improvement on the CRT- instead of a beam scanning and illuminating each pixel, there was an electron gun for each pixel, so you got true black and really good viewing angle and contrast. The problem was that they were inefficient and subject to burn-in, so once LCDs got good enough they discontinued them. I have one of the last Panasonic plasma TV’s and even though it is only 1080p it’s still my favorite screen because it looks great. I’m watching AMOLED prices but they’re still to high for my taste.

Irs not really Off its rather dimmed. Its saves energy, it prolongs it0s life and it has faster response time. Instead of turning on and off all the time pixels just get dimmed to 1% practicly black, and at the same time it prolongs its life. As for response time, again instead on/off it just modifies brightness, therefor haveing more accurate picture and fast pace.

I might be wrong but i always had that theory, it was the most logical one.