plasma display panel (PDP)
In a plasma display( PDP), noble gases are ionized in a gas cell by applying a voltage. The individual gas cells each form a pixel of the screen and are located between two glass plates on which transparent conductor paths made of indium tin oxide( ITO) are arranged in a matrix. The control voltages are transmitted via these.
The gas cellcontains the noble gases neon, xenon or argon and also the respective phosphor. Ionization of the noble gas is triggered by ignition of a voltage pulse. For this purpose, a voltage pulse of 80 volts is applied to the data electrode on the rear glass plate.
As 200 volts are simultaneously applied to the control electrode, the plasma ignites in the corresponding gas cell. The voltage pulse at the data electrode lasts only a few microseconds. After that, the ionization and thus the luminous state is maintained via the high control voltage.
During the plasma discharge, non-visible UV light with a wavelength of 170 nm to 190 nm is emitted. The UV light hits the phosphor and stimulates it to emit visible light. Depending on the color, the wavelength is between 380 nm and 780 nm. Barium compounds are used for blue, tin compounds for green and yttrium compounds for red. The light emitted by the phosphor exits via the front glass as a colored light spot.
The stable plasma state can be terminated by an opposite voltage surge. The radiation brightness depends on the ignition, burning and extinguishing voltage. The individual gas cells are embedded in a glass plate consisting of transparent conductor paths.
The advantage of plasma screens is their high luminous efficacy and large viewing angle. In addition, they are characterized by a high switching speed, which is interesting for video displays. The brightness values of plasma displays are over 1,000 cd/m2, and the contrast reaches values of 3,000:1.