The great innovation of this type of device lies in the way in which the pixels are activated, the small luminous points that form the image on the screen. In traditional television, this is done by a beam of electrons, which is emitted inside a large tube – that’s why the device has a lot of depth. In the new model, the pixels are tiny fluorescent lamps that contain plasma, an electrically charged gas that gives the device its name. As the microlamps are equivalent to the thickness of a strand of hair, the device has an extremely compact structure, looking like a picture to hang on the wall. In addition to reducing the depth of the TV to a few centimeters, the new technology also increased the image resolution by almost seven times. Other advantages are the flat screen, which avoids distortions, and images with more colors and brightness, in addition to less reflection problems. However, the principle used to form the images is basically the same on both televisions.
The pixels, distributed in horizontal lines, from left to right, and from top to bottom, are not activated all at once. Thus, each screen frame takes just over a millisecond to be completed. And it is exactly this sequence of appearance of the frames that creates the illusion of movement.
ORDINARY TV
1. A piece called a cathode emits a beam of electrons towards the screen. The light created by the beam triggers the pixels on the screen, which have three colors: red, green and blue. Depending on the light that each color receives, a dot is formed on the screen and the sum of all of them makes up the image.
2. All this takes place on the TV tube. But there needs to be internal space for the electron beam to be deflected by a magnetic field (controlled by the broadcaster’s signals) and manage to sweep the entire screen. The bigger the screen, the bigger the tube has to be.
PLASMA TV
1. The electron beam was replaced by microlamps, arranged side by side, forming a grid next to the screen. Each lamp is a pixel and has its own color (red, green or blue). The lamps are activated by electrodes connected to a video card, which receives signals from the station.
2. Each lamp has a mixture of gases inside. When they receive the command from the video card, the electrodes of a pixel release electrons that collide with the atoms of the gaseous mixture, transforming it into plasma, that is, a gas with electrically charged particles.
3. These particles are attracted by other particles of opposite charge and begin to collide, releasing ultraviolet light, invisible to the human eye. Ultraviolet light hits a phosphor layer of the lamp and, then, visible light appears. That is, one of the thousands of pixels on the TV was triggered to help compose the image on the screen.