This is a Utility Application filed on Feb. 1, 2008, which claims benefit from Korean Patent Application 10-2007-0059077 filed Jun. 15, 2007, which is incorporated herein by reference.
The present invention relates to a plasma producing device comprising magnesium oxide (MgO) microparticles having specific cathodoluminescence characteristics.
A general plasma display panel (PDP), schematically illustrated in
Recently, the characteristics of MgO have been widely studied because of the recognition that they play an important role in improving the efficiency of PDP. For example, there have been reports that high secondary electron emission (SEE) of MgO would may improve the discharge characteristics by reducing the discharge voltage (see [H. S. Uhm, E. H. Choi, and J. Y. Lim, Applied Physics Letters, 78(5), 592-594, 2001]), and that an increased level of oxygen defects in MgO may increase the secondary electron emission (see [Y. Motoyama, Y. Hirano, K. Ishii, Y, Murakami, and F. Sato, Journal of Applied Physics, 95(12) 8419-8424, 2004]).
Accordingly, there has been a need to develop MgO microparticles having a high content of oxygen defects, which is capable of improving the discharge characteristics of the plasma producing device.
Accordingly, it is an object of the present invention to provide a plasma producing device comprising magnesium oxide (MgO) microparticles having a high level of oxygen defects, which exhibits improved discharge characteristics in terms of low discharge voltage and short delay time.
In accordance with one aspect of the present invention, there is provided a plasma producing device comprising:
a first substrate;
at least one first electrode disposed on the surface of the first substrate;
a first dielectric layer formed on the surface of the first substrate, in which the first electrode is embedded;
a second substrate;
at least one second electrode disposed on the surface of the second substrate;
a second dielectric layer formed on the surface of the second substrate, in which the second electrode is embedded; and
partitions positioned between the first and second substrates defining a discharge space between the first and second substrates,
wherein the discharge space comprises magnesium oxide (MgO) microparticles whose cathodoluminescence emission shows no peak at a wavelength of 300 nm or less, but exhibits a peak at a wavelength in the range of 350 to 500 nm as well as at least one peak at wavelengths in the ranges of 550 to 650 nm and 700 to 800 nm when excited by an electron beam.
The above and other objects and features of the present invention will become apparent from the following description of the invention, when taken in conjunction with the accompanying drawings:
The present invention is characterized in that a plasma producing device, especially plasma display panel (PDP), comprises magnesium oxide (MgO) microparticles whose cathodoluminescence emission shows no peak at a wavelength of 300 nm or less, but exhibits a peak at a wavelength in the range of 350 to 500 nm as well as at least one peak at wavelengths in the range of 550 to 650 nm and 700 to 800 nm, said MgO microparticles being disposed in the discharge space between the first substrate and the second substrate.
The MgO microparticles having the specific cathodoluminescence characteristics according to the present invention can be prepared by combusting an Mg powder or a magnesium compound; or a mixture of an Mn powder or a manganese compound and an Mg powder or a magnesium compound under an oxygen atmosphere. For example, an Mg powder or an Mg-containing compound is subjected to combustion using a flame at a temperature ranging from 700 to 2200° C. to generate spontaneous combustion, followed by burning the combustion product under an oxygen atmosphere.
The MgO microparticles thus obtained may contain 1 to 1000 ppm of Mn. The Mn-containing compound used in the present invention can be manganese chloride or a manganese organic compound such as Mn[C5H7O2]2, and the Mg-containing compound used in the present invention can be MgCl2 or a magnesium organic compound such as Mg[C5H7O2]2, but is not limited thereto.
The amount of Mn contained in the metal mixture can be adjusted by changing the Mg to Mn mix ratio in the starting material.
The MgO microparticles thus obtained contain a trace amount of Mn ion (Mn2+) and have a cubic crystal structure and an average diameter ranging from several nm to several μm, preferably from 5 nm to 5 μm, whose cathodoluminescence emission shows no peak at a wavelength of 300 nm or less, but exhibits a peak at a wavelength in the range of 350 to 500 nm and at least one peak at a wavelengths in the ranges of 550 to 650 nm and 700 to 800 nm.
In accordance with the present invention, the intensity of the emission peak can be adjusted by varying the Mn content, and the amounts of oxygen defects generated in the MgO microparticles can be adjusted by varying the oxygen ratio.
MgO protective layer 4 is formed between the first dielectric layer 3 and the layer of the MgO microparticles 11 by deposition or sputtering.
A second substrate 8 is positioned and parallel to the first substrate 1 with a discharge space interposed therebetween.
At least one second electrode (address electrode) 9 is placed on the surface of the second substrate 8, and a second dielectric layer 6 is formed on the surface of the second substrate 8, in which the second electrode 9 is embedded.
Partitions 5 are disposed in the discharge space between the first and second substrates, and a phosphor layer 7 is formed to cover the side faces of the transverse walls, the vertical walls of the partitions 5 and the surface of the second dielectric layer 6. Discharge cells comprising the phosphor layer 7 with the three primary colors are arranged in the order of the red, green and blue in the transverse direction.
The inventive MgO microparticles having the above-mentioned cathodoluminescence emission characteristics can be desposed on the surface of the first dielectric layer 3, or optionally on the surface of the MgO protective layer 4 or on the surface of the phosphor layer 7 in the form of a layer (e.g. MgO layer 11, in
The MgO layer 11 may be formed by coating or laminating by a conventional spraying process, electrostatic coating process, screen printing process, offset process, dispenser process, ink-jet process or roll coating process to a thickness ranging from 100 to 2000 nm.
Alternatively, the MgO microparticles may be embedded in the phosphor layer 7.
The following Examples are intended to further illustrate the present invention without limiting its scope.
As shown in
The procedure of Example 1 was repeated except that the magnesium metal powder was mixed with an Mn metal powder (purity: 99.99%, Sigma Aldrich Co.) to raise the Mn content of the mixture to 2% weight, the resulting mixture being compressed into a pellet. The MgO microparticles thus prepared were analyzed with an ICP-AES. The result showed that the Mn content was 512 ppm.
The MgO microparticles obtained in Examples 1 and 2 were subjected to X-Ray Diffraction (XRD) analysis (M18XHF-SRA, MAC Science Co.). As shown in
Further, the MgO microparticles thus obtained in Examples were analyzed by scanning electron microscopy (SEM, FEI XL-30 FEG, Philips Inc.) and transmission electron microscopy (TEM, LIBRA 120, Carl Zeiss Inc.). The results are shown in
The MgO microparticles were into a pellet and placed in a chamber by scanning electron microscope (ESEM, FEI XL-30 FEG, Philips Inc.) for cathodoluminescence measurement. The cathodoluminescence of the MgO microparticles untreated with other metals was measured by cathodoluminescence detector (Mono-CL, Gatan Inc.), and the results are shown in
As shown in
As can be seen in Table 1, the delay time (td) of the opposed discharge cell coated with the MgO microparticles having the specific cathodoluminescence characteristic was markedly lower than the delay time (tp) observed for the existing discharge cell not coated with the MgO microparticles.
Further, the discharge voltages of the Samples A and B decreased by about 3 to 25% as compared with that of the existing discharge cell having no coated MgO microparticles.
As shown in
As described above, the inventive plasma producing device comprising magnesium oxide microparticles having the specific cathodoluminescence characteristics exhibit improved discharge characteristics in terms of low discharge voltage and short delay time.
While the invention has been described with respect to the above specific embodiments, it should be recognized that various modifications and changes may be made to the invention by those skilled in the art which also fall within the scope of the invention as defined by the appended claims.
Number | Date | Country | Kind |
---|---|---|---|
10-2007-0059077 | Jun 2007 | KR | national |