Patent Application
20050082980
This application claims the benefit of Korean Patent Application No. 2003-72139, filed on Oct. 16, 2003, which is hereby incorporated by reference for all purposes as if fully set forth herein.
1. Field of the Invention
The present invention relates to a plasma display panel and a discharge gas for exciting fluorescent material to emit visible light, and more particularly to a plasma display panel with enhanced brightness and efficiency due to the composition of the discharge gas.
2. Discussion of the Related Art
Plasma display panels (PDPs), which form images using an electric discharge, are widely used due to their excellent performance characteristics such as brightness and wide viewing angles. In a PDP, a voltage is applied to its electrodes to generate a gas discharge, which causes ultraviolet light to excite fluorescent material, thereby creating visible light (i.e. the displayed image).
PDPs are categorized as either alternating current (AC) or direct current (DC) types. In a DC type PDP, all of the electrodes are exposed to a discharge space, and electric charges move directly between the corresponding electrodes. In an AC type, at least one electrode is covered by a dielectric layer, and the discharge is performed by a wall charge, not by a flow of electric charges between corresponding electrodes.
PDPs are further categorized into facing discharge and surface discharge types. In the facing discharge type, each pair of sustain electrodes is separately formed on a front substrate and a rear substrate, and the discharge occurs perpendicularly to the substrates. On the other hand, in the surface discharge type, each pair of sustain electrodes is formed on the same substrate, and the discharge occurs parallel to the substrate.
Facing discharge type PDPs have high luminous efficiency, but their fluorescent layer is likely to be deteriorated by plasmas. Therefore, surface discharge type PDPs have become the standard.
Penning gas, which comprises neon (Ne) gas mixed with a low concentration of xenon (Xe) gas, is typically used as a PDP discharge gas. The discharge gas typically emits ultraviolet light of about 147 nm. With Penning gas, increased concentration of Xe gas typically leads to a decrease of visible orange light created by the Ne gas, thereby intensifying color purity. But the corresponding decreased concentration of Ne gas causes a sharp increase in the discharge starting voltage. Therefore, it is difficult to appreciably improve the PDP color purity while staying within a practical driving voltage range.
Accordingly, the present invention is directed to a discharge gas and a PDP that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
This invention provides a PDP with enhanced brightness and efficiency due to the composition of the discharge gas.
This invention further provides a discharge gas for exciting fluorescent material to emit visible light, wherein the discharge gas is a gaseous mixture of Ne gas, Xe gas, and Kr gas.
Additional features of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention.
The present invention discloses a PDP including a rear and front substrate that face each other and form a discharge space therebetween, wherein a discharge gas in the discharge space is a gaseous mixture of Ne gas, Xe gas, and krypton (Kr) gas. It further discloses the concentration of the Kr gas to be in the range of about 14% to about 44%.
The present invention also discloses a PDP comprising a rear substrate and a front substrate which face each other and form a discharge space therebetween, with a plurality of address electrodes formed in the upper surface of the rear substrate. A first dielectric layer is formed on the upper surface of the rear substrate to cover the address electrodes. A plurality of partition walls are formed on the upper surface of the first dielectric layer to partition the discharge space, and a plurality of sustain electrodes formed in the lower surface of the front substrate. A second dielectric layer is formed on the lower surface of the front substrate to cover the sustain electrodes, and a protection layer is formed in the lower surface of the second dielectric layer. A fluorescent layer is coated on the upper surface of the first dielectric layer and on the sides of the partition walls, and a discharge gas is filled in the discharge space, wherein the discharge gas is a gaseous mixture of Ne gas, Xe gas, and Kr gas, and the concentration of the Kr gas is in the range of about 14% to about 44%.
The present invention also discloses a discharge gas for exciting fluorescent material to emit visible light, wherein the discharge gas is a gaseous mixture of Ne gas, Xe gas, and Kr gas. And the concentration of the Kr gas is in the range of about 14% to about 44%.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention.
Reference will now be made in detail to an embodiment of the present invention, example of which is illustrated in the accompanying drawings.
A plurality of address electrodes 11 are arranged in stripes on the upper surface of the rear substrate 10, and they are covered by a first dielectric layer 12. A plurality of partition walls 13 are formed, at a predetermined interval, on the upper surface of the first dielectric layer 12 to prevent electric and optical interference between discharge spaces 14. A fluorescent layer 15 of red (R), green (G), and blue (B) colors is coated with a predetermined thickness on the inner surfaces of the discharge spaces 14. A discharge gas 30, which emits ultraviolet light during a discharge, is injected into the discharge spaces 14. The discharge gas 30 is composed of a mixture of Ne gas, Xe gas and Kr gas.
The front substrate 20, which is transparent so that visible light can pass through it, is usually made of glass, and it is joined together with the rear substrate 10. Striped pairs of sustain electrodes 21a and 21b, which are orthogonal to the address electrodes 11, are formed on the lower surface of the front substrate 20. The sustain electrodes 21a and 21b are made of transparent conductive materials such as ITO (Indium Tin Oxide) that allow visible light to pass through them. Metallic bus electrodes 22a and 22b are formed on the lower surface of the sustain electrodes 21a and 21b with narrower widths than the sustain electrodes to reduce the sustain electrodes' resistance.
A transparent second dielectric layer 23 covers the sustain electrodes 21a and 21b and the bus electrodes 22a and 22b. A protection layer 24, typically made of MgO (magnesium oxide), is formed on the lower surface of the second dielectric layer 23 to protect the second dielectric layer 23 from being damaged by the sputtering of plasma particles and to emit second electrons to lower discharge and sustain voltages.
A PDP having the above configuration is driven by address and sustain discharges. A wall charge is formed on the second dielectric layer 23 when an address discharge occurs between the address electrodes 11 and one of the sustain electrodes 21a and 21b. A sustain discharge occurs by a potential difference between the sustain electrodes 21a and 21b. As the sustain discharge occurs, the discharge gas emits ultraviolet light to excite the fluorescent layer 15 of the corresponding discharge space 14, thereby producing visible light. This visible light penetrates through the front substrate 20 as an image that viewers can recognize.
In an exemplary embodiment of the present invention, the discharge gas comprises a gaseous mixture of Ne gas, Xe gas, and Kr gas. The concentrations, by volume, of the Kr gas and the Xe gas are in the range of about 14% to about 44% (about 16% is preferred) and about 10% to about 26%, respectively. The discharge gas 30 pressure in the discharge space 14 is about 60 KPa.
Both the Xe gas and the Kr gas emit ultraviolet light. The Xe gas emits ultraviolet light of a wavelength of 147 nm as an excited Xe* is stabilized. And the Kr gas emits ultraviolet light of a wavelength of 146 nm as an eximer Kr2* is stabilized, where the eximer Kr2* is generated by collisions among unstable Kr*, stable Kr and a third element. As described above, because the Xe gas and the Kr gas emit ultraviolet light of almost the same wavelength, a fluorescent material, which emits visible light when excited by ultraviolet light of a wavelength of 147 nm, can be used in an exemplary embodiment of the present invention, as in the conventional art.
As the Xe gas concentration increases in the gaseous mixture, Xe in a stable state is transformed into excited Xe* by absorbing ultraviolet light of 147 nm. This self-absorption of ultraviolet light decreases the PDP's efficiency because that ultraviolet light is not available to excite the fluorescent layer 15. On the other hand, as the Kr gas concentration increases, this promotes more frequent collisions, as described above, and more eximer Kr2* is created, which means more ultraviolet light of 146 nm wavelength is emitted. However, stable state Kr is not transformed into eximer Kr2* by absorbing ultraviolet light of 146 nm, even though the concentration of the Kr gas increases. Therefore, the Kr gas does not absorb the ultraviolet light it creates, which increases the PDP efficiency because more ultraviolet light arrives at the fluorescent layer 15 when there is little to no self-absorption.
The Ne gas creates visible orange light, which negatively impacts PDP color purity, when a discharge occurs. In an exemplary embodiment of the present invention, when the Kr gas concentration increases, the Ne gas concentration decreases correspondingly, which may improve color purity.
Also, since a Kr atom is heavier than an Ne atom, the discharge gas 30 according to an exemplary embodiment of the present invention may be heavier than a conventional discharge gas. Increased mass of the discharge gas 30 decreases, kinetic energy of gas particles. Therefore, the sputtering rate on the protection layer 24 may drop, which may extend the PDP's lifespan.
As described above, PDP brightness and luminous efficiency may be enhanced, and its lifespan may be extended, when the gaseous mixture of Ne gas, Xe gas and Kr gas is used as the discharge gas, and the concentration of the Kr gas is in the range of about 14% to about 44%.
Thus, the PDP according to an exemplary embodiment of the present invention may improved the color purity, luminous efficiency and extend the PDP lifespan.
While an exemplary embodiment of the present invention has been described in relation to a PDP, the discharge gas of the present invention is not limited to use in a PDP or in a PDP as illustrated herein.
It will be apparent to those skilled in the art that various modifications and variation can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended Claims and their equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2003-0072139 | Oct 2003 | KR | national |
