1. Field of the Invention
The present invention relates to a plasma display device, and more particularly, to a plasma display device having a conductive strip or matrix for preventing occurrences of an electromagnetic wave.
2. Description of the Related Art
Plasma display devices utilize a gas discharge to form display images. The plasma display device has emerged as a flat panel display comparable to a cathode ray tube (CRT) in terms of picture quality since it exhibits excellent display properties such as display capacity, brightness, contrast, after-image, viewing angle, and the like. In plasma display devices, when an AC or DC voltage is applied to electrodes, a gas discharge is generated between the electrodes and the resulting radiation of ultraviolet light excites phosphors to emit light. Since the voltage required to generate a gas discharge is so high in plasma display devices, electromagnetic waves are generated, which may adversely affect humans.
FIG. 1 is an exploded perspective view showing the structure of a general AC-type plasma display device. Referring to FIG. 1, a first electrode 13X, which is a common electrode, and a second electrode 13Y, which is a scan electrode, are formed on the inner surface of a front glass substrate 11, the two electrodes forming a pair. A third electrode 13A, which is an address electrode, is formed on the inner surface of a rear glass substrate 12. The first and second electrodes 13X and 13Y, and the third electrodes 13A, respectively, are strips on the inner surface of the front and rear glass substrates 11 and 12. When the substrates 11 and 12 are put together, the first and second electrodes 13X and 13Y, and the third electrodes 13A cross each other perpendicularly. A dielectric layer 14 and a protective layer 15 are sequentially stacked on the inner surface of the front glass substrate 11. Barrier walls 17 are formed on the top surface of a dielectric layer 14xe2x80x2 which covers the rear glass substrate 12, and cells 19 are defined by the barrier walls 17. An inert gas such as argon fills the cells 19. Further, each cell 19 is coated with phosphors 18 corresponding to red(R), green(G), or blue(B) pixels. Although not shown in FIG. 1, a bus electrode may be formed along the first and second electrodes 13X and 13Y.
The operation of a plasma display device having the above structure will now be described. First, a high voltage, which is called a trigger voltage, is applied to produce a gas discharge between the first and third electrodes 13X and 13A. Then, a discharge is created when positive ions are accumulated on the dielectric layers 14 and 14xe2x80x2 by the trigger voltage. If the trigger voltage exceeds a threshold voltage, then argon gas within the cells 19 changes to a plasma state, and a stable discharge state can be maintained between the adjacent first and second electrodes 13X and 13Y. In the stable discharge state, ultraviolet light among discharge light bombards the phosphors 18 to produce light, which allows each pixel formed on a cell-by-cell basis to display an image.
The plasma display device described above generates electromagnetic waves when displaying an image. The harmful electromagnetic waves are emitted directly to users through the front surface of the display device. In order to prevent radiation of electromagnetic waves, usually a transparent conductive layer is formed on the surface of the front glass substrate 11 and grounded. However, the material used for transparent conductive layer is expensive and may degrade the brightness of the display device.
To solve the above problems, it is an objective of the present invention to provide a plasma display device including an improved electromagnetic-wave shielding means.
It is another objective to provide a plasma display device having a means for improving the contrast as well as blocking electromagnetic waves.
Accordingly, to achieve the objectives, the invention provides a plasma display device including: front and rear substrates; strips comprised of a conductive material, which are formed on the front substrate, and an insulating layer formed so as to cover the conductive strips; first and second electrodes disposed parallel to each other on the insulating layer and a dielectric layer formed so as to cover the first and second electrodes; third electrodes formed perpendicular to the first and second electrodes on the rear substrate, and a dielectric layer formed over the interior surface of the rear substrate so as to cover the third electrodes; barrier walls which form discharge spaces on the dielectric layer of the rear substrate; and red, green, and blue phosphors coated between the barrier walls.
The conductive strips are extended along positions right above the barrier walls. The conductive strips are extended in parallel to the first and second electrodes in non light-emitting regions disposed between the pairs of first and second electrodes. Furthermore, The conductive strips are grounded. The conductive material is copper silver, indium tin oxide (ITO), or photosensitive silver paste. The conductive strips are formed by overlapping black strips disposed toward the outside of the front substrate and white strips disposed toward the inside of the front substrate.
The present invention also provides a plasma display device including: front and rear substrates; matrices comprised of a conductive material which are formed on the front substrate, and an insulating layer formed so as to cover the matrices; first and second electrodes formed parallel to each other on the insulating layer and a dielectric layer so as to cover the first and second electrodes; third electrodes formed perpendicular to the first and second electrodes on the rear substrate, and a dielectric layer formed over the interior surface of the rear substrate so as to cover the third electrodes; barrier walls which form discharge spaces on the dielectric layer of the rear substrate; and red, green, and blue phosphors coated between the barrier walls.