Television

A modern LED-backlit LCD television is a box of light and switches. Behind the front glass sit millions of tiny shutters, each deciding how much light to let through. Together they draw the picture, redrawn 60 or more times a second.

The build comes together from a few main assemblies:

• The LCD panel, which forms the picture from millions of red, green and blue subpixels.
• The backlight unit, a tray of white LEDs and optical sheets that lights the panel evenly from behind.
• The main board, the TV's computer, which takes in video from HDMI, an antenna or the internet and decodes it.
• The timing controller board, which turns each frame into row-by-row signals for the panel.
• The power supply board, which turns wall power from the power cord into the low voltages everything else needs.

Final assembly is mostly mechanical. The panel sits on the backlight inside a frame, and the boards are fastened to the back with screws. Flat flexible cables carry picture data and a wiring harness carries power. Speakers, an infrared receiver, the bezel, the back cover and the stand finish the set, and a remote control goes in the box.

Here is how a picture gets made. The main board decodes a frame and passes it to the timing controller, which tells the panel's driver chips what voltage each subpixel needs. Each voltage turns the liquid crystal in that subpixel, so more or less of the backlight's white light gets through its color filter. Your eye blends the dots into one image. The main rival design is OLED, where every subpixel makes its own light and no backlight is needed.