Yellow ZnS-based phosphor, process of preparing the same and display device using the phosphor

#This application claims the benefit of Korean Application No. 02-21558, filed Apr. 19, 2002 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.

#1. Field of the Invention

#The present invention relates to a yellow ZnS-based phosphor, a process of preparing the same and a display device using the phosphor. More particularly, the present invention relates to a yellow phosphor achieved by a ZnS-based host material having improved color coordinates and luminance for use in intermediate- and low-voltage display devices, and a process of preparing the same.

#The above and/or other features and advantages of the present invention will become more apparent and more readily appreciated by describing in detail embodiments thereof with reference to the accompanying drawings in which:

#FIG. 1 is a graphical representation showing color coordinates of a conventional Mn activated ZnS-based (ZnS: Mn) phosphor and an Mn, Cu activated ZnS-based (ZnS: Mn, Cu) phosphor according to Example 1 of the present invention;

#FIG. 2 is a cross-sectional view of a vacuum fluorescent display (VFD) using the phosphor of the present invention; and

#Reference will now be made in detail to the present embodiments of the present invention, examples of which are illustrated in the accompanying drawings and in specific Examples, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures and specific Examples.

#In order to improve color purity and luminance of a conventional ZnS-based phosphor, and to control emission color, the present invention provides a highly advantageous yellow ZnS-based phosphor.

#The CIE chromaticity coordinates of the conventional ZnS: Mn phosphor are x=0.55 and y=0.43, which corresponds to the orange emission color. However, in order to provide a yellowish hue, copper is added as a second activator, thereby improving the color purity. The addition of copper as a second activator to the conventional ZnS phosphor containing Mn as a first activator results in a change in the emission spectrum of Mn such that the emission wavelength of Mn becomes a little bit shorter. As a result, in the CIE chromaticity diagram, the x-coordinate is further decreased and the y-coordinate is further increased, thereby providing a yellow emission as compared to the conventional Mn activated ZnS phosphor. Thus, the Mn, Cu activated ZnS phosphor according to the present invention has color coordinates corresponding to a pure yellow emission.