Title of Invention

RED FLUORESCENCER COMPOSITION FOR COLOR CATHODE-RAY TUBE

Abstract

An europium activated yttrium oxysulfide fluorescencer composition for color cathode-ray tube is disclosed, wherein a first red fluorescencar with predetermined particle ei2e and a second red fluorescancer with smaller particle size are mixed and Said first fluorescencer and second fluorescencer comprises respectively 0.07 - 0.08 g atomic weight of europium as an activator relative to l mole of yttrium oxysulfide as a mother body.

Full Text

BACKGROUND Off TH3 IK¥BNTION Field of the invention Tho present invention relates to a red fluorescencer Composition for color cathode-ray tube. More particularly, the c , px-caent invention relates to a red f luorescencer composition u-v color cathode-ray tube which enables to enlarge the range qf color reproduction arid at tho tsama time to prevent the deterioration of relativ« luminous efficiency of a red f1uoreacencer composition. Daooriptlon of the Prior Art A method for preparing a fluorescent plane for color cathode-ray tube in diclosed in USP 4,307,320, wherein green and blue fluorescent bodies are applied on inner surface of panel on which black matrix is formed. After exposure to light, europium activated yttrium oxysulfide red fluorescencer composition (YiOzS:Kvi) comprising 0.01 - O.OG6 g atomic weight of europium as an activator relative'to 1 mole of yttrium oxysulfide, is applied to the above panel formed and it is light-exposed to provide a screen plane for color cathode-ray tuba. However, there has been a problem that europium activated yttrium oxyuulfide red fluorencencer composition (YzOS:Eu) Having above composition has deteriorated color purity caused by low x-coordinate value and high y-coordinate value on a C.I.E. chromaticity diagram and does not satisfy the range of color reproduction similar to natural color which has been required recently. SUMMARY OF THE INVENTION The present invention is intended to provide the red fluorescencer composition for colour cathode-ray tube, which enables to enlarge the range of color reproduction and at t he same time to prevent the deterioration of relative luminous efficiency of red fluorescencer by enhancing the colour purity of europium activated yttrium oxysulfide red fluorescencer composition. The above object of the present invention has been achieved by europium activated yttrium oxysulfide red fluorescencer composition(Y2O2S:Eu) for color cathode ray tube wherein a first red fluorescencer with predetermined particle size and a second red fluorescencer with smaller particle size are mixed and the first fluorescencer and the second fluorescencer comprises respectively 0.07-0.08 g atomic weight of europium as an activator relative to 1 mole of yttrium oxysulphide as a mother body. There is no chemical reaction between the ingredients of the claimed composition. The composition is having a synergistic effect. STATEMENT OF INVENTION This invention relates to a red fluorescencer composition for color cathode ray tube characterized by: a first red fluorescencer with predetermined particle size and a second red fluorescencer with smaller particle size are mixed and said first fluorescencer and said second fluorescencer comprises respectively 0.07-0.08 g atomic weight of europium as an activator relative to 1 mole of yttrium oxysulphide as a mother body BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a spectrum of the red fluorescencer composition with 0.08 g atomic weight/mole of europium content according to the present invention; Fig, 2 is a spectrum of the red fluorescencer composition with 0.0? g atomic weight/mole of europium content according to the presant invention; Fig. 3 is a C..I.E, chroraaticity diagram for the red fluorescencer composition according to the present invention; and Fig. 4 is a cross-sectional view for the red fluorescent screen formed by the red fluorescencer composition according to the present invention. DETAILED OBSCRIPTICIM OT THB IHVSMTION According to the present invention, europium activated yttrium oxysulfide red fluorescencer composition comprising 0.07 - 0.08 g atomic weight of europium as an activator r*lative to 1 mole of yttrium oxysulfide as a mother body, is applied on inner surface of panel, wherein green and blue fluorescent bodies are applied, and then it is light-exposed to form the fluorescent plane for color cathode-ray tube. The x- and y-coordinate values of europium activated yttrium oxysulfide red fluorescencer composition (Y2O2S:Eu) on the chromaticity diagram will be changed Dependents on the content • proportion of yttrium oxysulfide as a mother body and europium ac an activator. Ae shown in Fig. 3, in the red fluorescencer ^ .,. . ,~ . , . _ composition according to~the present invention, color point on the C.I.E. chromaticity diagram is X=0.645, Y=0.352 in case of 0.07 g atomic weight of europium content and X=0.651, Y=0.347 in cane of O.08 g atomic weight of europium content. Hence, aa the content of europium is increased, x-coordinate value of the red fluorescencer composition on the chroznaticitv diagram is increased and y-coordinate value is decreased and these result in enhancement of color purity and enlargement of the range of color reproduction towards natural color. However, as shown in Table 1 described below, there has been a problem that relative luminous efficiency of the red f luorcoscencer composition is lowered as the europium content is increased. At this time, relative luminous efficiency is a value based on light intensity emitting fluorescent light when light sourca with stabilized intensity is applied to a r»d fluorescencer composition wherein particle size is 7 - 8 JOT and Eu content is 0.070 g atomic weight. To solve th* problem, as shown in Pig. 4, the red fluorescencer composition of the present invention comprising a first red fluorescencer(3) with a particle size of 7 - 8 /un and a second r*d fluorescencer(4) with a particle size of 3 - 5 f^m by mixing, ie used to form a fluorescent screen on the «r ' '' black matrix(2) over panel (1) and this prevents the deterioration of relative luminous efficiency by enhancing the screen filling property, Table 1 (Table Removed) As shown in Fig. 1 and 2, in above europium activated yttrium oxysulfide fluorescencer composition (Y2O2S:Eu), luminous wavalength in ragion of visible light moves towards short-wavelength as europium content relative to 1 mole of yttrium oxysulfide aa a mother body increases. \nd as shown in Table 2 described below, the intensities of luminous peaks at 586 nre, 555 nm, 539 nm and 513 nm in region of visible light in increased compared to main luminous peak at 626 ntt as europium content decreases. [ Table 2 ] (Table Removed) Therefore, as europium content decreases, x-coordinate value is decreased and y-coordinate value is increased on the chromaticity diagram in Fig. 3- As mentioned above, in case that europium content decreases, Iriainous intensity in region of short-wavelength increases beyond a relatively pure red luminous region and color purity is deteriorated as a result. Hence^ color purity of rod fluorescencer will be enhanced and the range of color reproduction will be enlarged by using europium activated yttrium oxyaulfide fluorescencer composition (Y2O2S:Eu) of the present invention wherein europium content is increased to 0.07 - 0.08 g atomic weight relative to 1 »ole of yttrium oxysulfida as a mother body. AB roention*d above, however, there has been a problem that relative luminous efficiency is lowered and red monochromatic brightn«ss is deteriorated by increasing europium content. such problem will be solved by using the red fluorescencsr composition wherein a first red fluorescencer with predetermined particle size and a second red fluore-scancer with smaller particle size are mixed, when the red fluorescencer composition comprising two types of red fluores-cencer with different particle sizes by mixing is applied on fluorescent screen, deterioration of the luminous efficiency ie prevented due to enhancement of the screen filling property. For example, when the red fluorescencer composition wherein two types of red fluorescanoer with a particle size of 7 - 8 pm and 3- 5 /im respectively are mixed is used, relative luminous efficiency of dot or stripe on screen for cathode-ray tube is illustrated in Table 3 below. (Table Removed) Note) A red fluorscencer composition of the present Invention having a particle size of 7 - 8 pm; and 8 : rad fluoreacencer composition of the prwent invention having a particle size of 3- 5 µm As mentioned above, according to the present invention, increasing the activator content of europium activated yttrium oxysulfide red fluorescencer composition results in enhancement of color purity of red fluorescencer and then enlargement of color reproduction range. j Further, by uaing the red fluorescencer composition of tha present invention comprising a first red fluoresccncer with pr eclat errai nod particle size and a second red fl-uor«sccncer with smaller particle size by mixing, detarioration of the luminous efficiency caused by increasing of above activator amount is prevented due to enhancement of the screen filling property. We claim: 1. A red fluorescencer composition for color cathode ray tube characterized by: a first red fluorescencer with predetermined particle size and a second red fluorescencer with smaller particle size are mixed and said first fluorescencer and said second fluorescencer comprises respectively 0.07-0.08 g atomic weight of europium as an activator relative to 1 mole of yttrium oxysulphide as a mother body 2. A composition as claimed in claim 1, wherein in particle size of said fluorescencer is 7-8um and particle size of said second fluorescencer is 3-5 urn. 3. A composition as claimed in claim 2, wherein a ratio of said first fluorescencer to said second fluorescencer is 0.25-4. 4.A red fluorescencer composition as substantially herein illustrated and described in the accompanying drawings.

Documents:

303-del-1996-abstract.pdf

303-del-1996-claims.pdf

303-del-1996-complete specification (granted).pdf

303-del-1996-correspondence-others.pdf

303-del-1996-correspondence-po.pdf

303-del-1996-description (complete).pdf

303-del-1996-drawings.pdf

303-del-1996-form-1.pdf

303-del-1996-form-2.pdf

303-del-1996-form-26.pdf

303-del-1996-form-3.pdf

303-del-1996-form-6.pdf

303-del-1996-petition-others.pdf