Green PDP
Introduction to PDP
Plasma Display Panel (PDP)
Plasma display is an element that displays text or graphics using the light from plasma, generated during gas discharge. Plasma displays are divided into the direct current and alternating current types. The electrode used to supply voltage from the outside and to create plasma is exposed to the plasma directly, and a conduction current flows directly through the electrode, which is of the direct current type.
Plasma displays are also mainly categorized as the partners facing discharge type, surface discharge type, and barrier rib discharge type, in accordance with the electrode structure of the discharge cell. Generally, for single color display PDP (plasma display panel) elements, visible rays are used directly from the discharge gas. As a typical example, a plasma display panel uses the orange color emitted by Ne gas. If a full color display is required, ultraviolet rays from the discharge gas, such as en or Xe excited red, green, and blue phosphors, are used to generate visible light.
Characteristics of PDP
PDPs have many advantages that allow the making of full-size flat displays using liquid crystal display (LCD), field emission display (FED), and electroluminescence display (ELD) technologies, on which active research and development are being carried out. The plasma formation method allows PDPs to have large-size flat screens. Its structure consists of two glass substrates with a thickness of 3 mm, and the electrode and phosphors are coated on each substrate. Then, 0.1~0.2 mm gap is maintained between the two substrates, and in the space between, them plasma is formed. It is very likely that PDPs are manufactured as wall-hanging HDTVs, with a large-size flat screen of over 40", owing to their following properties.
Very Strong Nonlinear Characteristic
Despite voltage being supplied between electrodes, gas discharge does not occur if voltage supplied is below the discharge starting voltage, which is a very strong nonlinear characteristic. Thus, in large size panels with over 1000 pixels per a line, the line addressing method can use optional discharges, which implies that for addressing a panel of 1000 × 1000 discharge cell, only 2000 addressing circuits are required instead of 100 million lines. With the help of this feature, a grayscale display using the digital method can be realized. Currently, a Full Color PDP with a 256-level grayscale display capability is under development.
Memory Function
PDPs determine the next state using previous conditions, which is termed the memory function of PDP. In the case of an AC type PDP, memory addressing is possible through a wall electric charge formed on a dielectric. In the case of a DC type PDP, memory addressing is possible by using the pulse memory method. A memory function is imperative for addressing in large-size displays. When addressing is performed by using such a memory method, a super-large panel can display images with the best quality without any reduction in image brightness.
Long Life Span
AC type PDPs have a long life span because they use preventive layers such as MgO, which have a suitable sputtering characteristic, whereas DC type PDPs have a long life span because they employ current control resistance, seals a little amount of Hg or increase gas pressure, which leads to ion shock, and, it reduces sputtering damage of electrode substance. From the perspective of life span, AC type PDPs last much longer. Currently, products using AC type PDPs are guaranteed to last 20,000 hours. In principle, it is possible for such products to last for more than 10,000 hours.
Optical Viewing Angle
PDPs have a wide viewing angle as they are self-emissive displays. Both AC and DC type PDPs have >160° wide viewing angles in every direction, which matches the typical viewing angle size in CRTs.
Easier Full Color Realization
Color realization in PDPs is achieved through the photoluminescence mechanism, by which ultraviolet rays generated from a discharge stimulate a phosphor layer and cause the radiation of visible rays. This allows the display to reproduce color close to the level achieved by CRTs. Thus, excellent full color realization is possible through the enhancement of brightness and the achievement of a high contrast by advanced technology.
Heat- and Cold-resistance
The plasma generated at each pixel in a PDP is negligibly influenced by the barrier rib or the electrode in the approximate temperature range of -100°C to 100°C. Hence, the temperature range suitable for addressing in a PDP is determined by a semiconductor device used in the addressing circuit.
Light Weight
If we manufacture a CRT with a 40 inch size, the TV that uses it is overweight at 100 kg. However, a PDP with the same size weighs no more than 20 Kg, and its weight can be further reduced by making components lighter.
“Plasma is a quasineutral gas containing charged and neutral particles that exhibit collective behavior”
In general, matter exists in various states: solid, liquid, and gas. The basic building blocks of the materials in these states are either molecules (an atom or a collection of atoms) or compounds. Plasma is a state of matter in which the electrons of an atom, molecule, or compound can move freely in and out of orbits without being constrained by the nucleus.
Usually, at normal temperature and pressure, if matter existing in a solid state is given energy and raised to a high temperature, it turns into a liquid by melting. When more energy is supplied, thereby increasing its temperature, the liquid turns into gas. If even more energy is supplied to the matter in gaseous form, the next phase, i.e., the fourth state of matter, is achieved, which is called the plasma state.
