Plasma vs. LCD

Difference Between Plasma And LCD

Plasma

The first commercial plasma screen was developed in the early nineties. The image on the screen is displayed as a result of three basic colors: red, green and blue. In plasma screen each pixel has three sub-pixels which correspond to the three primary colors. The intensity of the three primary colors for each pixel is multiplied by the huge number of pixels.

Each sub-pixel consists of a micro-container of LPG (Xeon) with two electrodes, one at front and one at rear. When high voltage of AC is applied, the gas is put in motion (plasma).  This causes the issue of ultraviolet rays. To make this type of radiation visible, special devices are used. These devices are called scintillators which cause the production of a frequency of visible light to human eye.

In the plasma screen the light source is internal. The liquid gas contained in each cells is excited by a magnetic field. As a result light is produced. The phosphorus covering the cell emits light. The picture quality is very high. The main drawback of plasma screens is that it is impossible to reduce the size of the individual pixels less than 0.5 mm. This implies that the minimum diagonal of the screen must be 32 inches.  You may have problems of static images for long periods because of aging of scintillators. If a single image is projected on the screen for a very long time,  it may be impressed on scintillators.

The viewing angle of a Plasma screen is much larger than a LCD screen because the light comes directly from single pixel and not from a source of illumination and therefore does not require polarization. For this reason, the Plasma screen is much more contrasted and bright compared to a LCD. The black in the plasma is really black because the pixel is turned off and does not emit any light. Another problem with the pixel structure is that they can only be on or off. To overcome this problem and recreate the various light intensities it uses a system of pulse code modulation. However, this mechanism can make viewing Plasma annoying or tiring for the eyes at close range. So, the increase of the diagonal helps in distance vision. From the economic point of view plasma screen is more expensive compared to an LCD.

LCD

The first LCD (Liquid Crystal Display) screen was developed in 1995. Its main feature is that the screen image is the result of orientation of light. The light source is external. From the technical point of view also LCD screen is based on the system of three primary colors for each pixel. The LCD screen does not emit any light of its own, and that’s why it needs a source of backlight. Each individual sub-pixel forms a sort of valve that lets colored light come through the crystal. The principle behind this type of technology is the ability of liquid crystal to revise its structure from time to time on the basis of electric current passed through it.

For proper operation, light generated by the backlight must be white in color and should not be polarized.  The LCD screens have a very high resolution and can reach considerable size, have power economy. It is extremely durable and has lower cost compared to plasma screens. The main weakness of the LCD screens is its diagonal of view which is not very wide.

Category: Computers & Electronics  |  Tags: