Reference / Paper · 1998
US Patent 5,825,124 — Ohno et al., Cathode-Ray Tube Having Activated Green and Blue Phosphors (1998)
Includes a table of P22-type phosphor afterglow, used for decay times in CRT Timing Vol 2.
- crt
- phosphor
- afterglow
- p22
Reference / Paper · 1998
Includes a table of P22-type phosphor afterglow, used for decay times in CRT Timing Vol 2.
US005825124A United States Patent [19] [11] Patent Number: 5,825,124 Ohno et al. [45] Date of Patent: *Oct. 20, 1998 [54] 3,860,753 4,510,414 4,772,818 1/1975 Tsuneta et al. ................... .. 313/475 X 4/1985 Fujino et al. ....... .. 313/468 9/1988 Koike et al. . 313/468 X 5,569,977 10/1996 CATHODE-RAY TUBE HAVING ACTIVATED GREEN AND BLUE PHOSPHORS [75] Inventors: Katsutoshi Ohno, Tokyo; Tsuneo Kusunoki, KanagaWa; Kenji FOREIGN PATENT DOCUMENTS Takayanagi, KanagaWa; Masaru Ihara, KanagaWa, all of Japan 156649 156787 199090 199091 199092 161083 860170 [73] Assignee: Sony Corporation, Tokyo, Japan [*] Notice: DonoFrio .............................. .. 313/466 This patent issued on a continued pros 12/1981 8/1985 10/1985 10/1985 10/1985 6/1989 8/1981 Japan ................................... .. 313/467 Japan . .. Japan . Japan . Japan . Japan .. ecution application ?led under 37 CFR 1.53(d), and is subject to the tWenty year patent term provisions of 35 U.S.C. Primary Examiner—Michael Brock 154(a)(2). Assistant Examiner—Daniel S. Larkin U.S.S.R. .............................. .. 313/467 Attorney, Agent, or Firm—Hill & Simpson [21] Appl. No.: 619,293 [22] [30] Filed: Foreign Application Priority Data Mar. 23, 1995 [51] [52] [58] Mar. 21, 1996 [JP] Japan .................................. .. 7-064416 Int. Cl.6 .................................................... .. H01J 29/20 US. Cl. ................ .. 313/467; 313/468 Field of Search .................................... .. 313/467, 468 [56] References Cited U.S. PATENT DOCUMENTS 3,673,102 3,688,144 6/1972 Lehmann et al. ................ .. 252/301.45 8/1972 Harao et al. .......................... .. 313/475 [57] ABSTRACT A cathode-ray tube includes a phosphor screen having a tricolor phosphor layer composed of a red phosphor, a green phosphor of ZnS:Cu, Al activated With Ni, Fe, or C0, and a blue phosphor of ZnS:Ag activated With Ni, Fe, or C0. The green phosphor and the blue phosphor have a decay intensity of at most 0.5% upon elapse of 8 milliseconds after excita tion is removed therefrom. The green phosphor of ZnS:Cu, Al activated With Ni and the blue phosphor of ZnS:Ag activated With Ni have their afterglow characteristics sub stantially equalized to the afterglow characteristics of the red phosphor of Y2O2S:Eu. 4 Claims, 4 Drawing Sheets U.S. Patent 0a. 20, 1998 Sheet 1 of4 5,825,124 F / C1‘. 7 (PRIOR ART) 120_ I ——0—ZnSIAg.C1 100 - 1 > 80: ° : — l3--ZnS:Cu,A1 \ —<>"Y2O2SIEu ggeo.“ U'l .. 22540; E5 8:’ E 20: OI ._.2FLlllnlllllLllllllllllll (22 O 2 4 6 8 10 Time (msec) F / G. 2 (PRIOR ART) Time (msec) U.S. Patent ____6h_____.__.__2 O E!38:_35 9>20m80 0a. 20, 1998 Sheet 2 of4 5,825,124 3i mmm Wm- .m11 .m1 NWNl MW.A-WQ M m /n000 m ew+i6_ 10 mnm..8wmw )O l2 Time (msec) l4 F / G. 4 9>502m80 36:25 4 6 Time (msec) 4 6 Time (msec) 10 U.S. Patent 0a. 20, 1998 Sheet 3 of4 5,825,124 FIG. 5 9>502m30 |1|l|||l|l|l||1l1|| Time (msec) I‘'I:I~\6\ E!36:3_5 1/021O 9>502m30 \t‘.(Io:+.lI‘‘ X.I.\l.\|\on“_(l“nnlf0UP‘.1\)a'5“l")kw“ lud-IIW 6 0 r._. ... \ . .. 5. iniItiaI.l“". l2l.‘) v-m h, .N .. w l nu .\ -.. mmn 4|um. lto?“"\IT|_ G. . I. ‘t v.i - |8.J Aw... ‘mI‘l 16.T. 10 Time (msec) U.S. Patent 0 ct. 20, 1998 5,825,124 Sheet 4 0f 4 F/G. 902 so: RLeulmaintainvce 70: 50i 4 OO 1 1 1 l l l | l | | 4 6 Concentration ( ppm) FIG. 100 90 so; 70; LRuemliantainvce 60; so: 40: 30' Concentration (ppm) | | | | 5,825,124 1 CATHODE-RAY TUBE HAVING ACTIVATED GREEN AND BLUE PHOSPHORS TABLE 1 BACKGROUND OF THE INVENTION Red: Y2O2S: Eu Green: Zns: Cu, A1 Blue: ZnS: Ag 1. Field of the Invention The present invention relates to a cathode-ray tube having a phosphor screen With improved green and blue phosphors. 2. Description of the Related Art There has recently been developed a three-dimensional 8 msec. 16 msec. 1.9 msec. 7.5 msec. 7.0 msec. 0.25% 0.95% 0.9% 0% 0.6% 0.5% It can be seen from Table 1 that the green and blue phosphors have aftergloW times longer than the red phos phor. In order to avoid a reduction in the quality of displayed images, cathode-ray tubes are designed to meet such a television system having a direct vieWing display tube for displaying three-dimensional images based on the parallax of the right and left eyes of the vieWer. For displaying requirement that the aftergloW intensity after excitation be at most 0.5% of the maximum aftergloW intensity peak. For the three-dimensional images on the three-dimensional televi sion system, tWo images to be vieWed respectively by the right and left eyes of the vieWer are produced by cameras, 1: (V100) 15 compressed vertically, and combined into a single image. three-dimensional television system (With the vertical scan ning frequency of 120 HZ), as shoWn in Table 1, the aftergloW intensities of the green and blue phosphors after elapse of 8 milliseconds are 0.95% and 0.9%, respectively. The combined single image is then converted into a MUSE Therefore, the green and blue phosphors of the cathode-ray signal, Which is recorded. The recorded MUSE signal is reproduced, supplied to a cathode-ray tube, and scanned at 20 tube of the three-dimensional television system produce such aftergloW intensities that impair the quality of dis a vertical scanning frequency of 120 HZ, Which is tWice an played images. ordinary vertical scanning frequency of 60 HZ, so as to be restored to its original siZe, for thereby alternately display ing images for the right and left eyes, each in 1/120 second. SUMMARY OF THE INVENTION For the vieWer to see a three-dimensional image, the 25 vieWer Wears three-dimensional glasses having liquid crystal shutters for the right and left eyes, and the liquid crystal shutters are alternately sWitched, each in 1/120 second, in timed relation to the image, i.e., the ?eld period. The It is therefore an object of the present invention to provide a cathode-ray tube including a phosphor screen Which ering through the three-dimensional glasses. ordinary cathode-ray tube. comprise phosphors in three colors that have uniform after gloW characteristics even if the ?eld frequency of the vieWer can vieW a three-dimensional image free from ?ick 30 cathode-ray tube is three times the ?eld frequency of an According to the present invention, there is provided a phosphor layer for a phosphor screen of a cathode-ray tube, comprising a red phosphor, a green phosphor having a host In order to avoid undesirable ?ickering of a three dimensional image displayed on the direct vieWing cathode ray tube of the three-dimensional television system, the vertical scanning frequency, i.e., the ?eld frequency, of the 35 material of ZnSzCu, Al and an activator for the green phosphor selected from the group consisting of Ni, Fe, Co in cathode-ray tube is 120 HZ Which is tWice the vertical an amount of at most 10 ppm relative to the host material, scanning frequency of an ordinary cathode-ray tube. and a blue phosphor having a host material of ZnSzAg and Therefore, since the period of each ?eld is smaller, if the an activator for the blue phosphor selected from the group image for the left eye in a preceding ?eld remains displayed consisting of Ni, Fe, Co in an amount of at most 10 ppm 40 on the cathode-ray tube due to the aftergloW, i.e., decay, of relative to the host material. the phosphors of the phosphor screen of the cathode-ray tube According to the present invention, there is also provided When the image for the right eye in a present ?eld is being a cathode-ray tube including a phosphor screen Which has a displayed on the cathode-ray tube, then the tWo images are phosphor layer comprising a red phosphor, a green phosphor simultaneously displayed on the cathode-ray tube. having a host material of ZnSzCu, Al and an activator for the On color cathode-ray tubes, there have been used phos 45 green phosphor selected from the group consisting of Ni, Fe, phors in three colors, i.e., a red phosphor of Y2O2S:Eu, a Co in an amount of at most 10 ppm relative to the host green phosphor of ZnszCu, Al and a blue phosphor of ZnS: Ag. Particularly, the green and blue phosphors emit a longer aftergloW, i.e., decay, impairing the quality of images Which are displayed. 50 FIGS. 1 and 2 of the accompanying draWings shoW aftergloW curves of usual red, green, and blue phosphors of material, and a blue phosphor having a host material of ZnSzAg and an activator for the blue phosphor selected from the group consisting of Ni, Fe, Co in an amount of at most 10 ppm relative to the host material. Each of the activator for the green phosphor and the activator for the blue phosphor is present in an amount ranging from 2 to 10 ppm. a color cathode-ray tube Which Were excited by an electron beam. FIG. 2 shoWs at enlarged scale the decay of the red, The green phosphor and the blue phosphor have a decay green, and blue phosphors. In FIG. 2, the curve I represents 55 intensity of at most 0.5% upon elapse of 8 milliseconds after the aftergloW curve of a red phosphor of Y2O2S:Eu, the excitation is removed therefrom. curve II a green phosphor of ZnszCu, Al, and the curve III a blue phosphor of ZnSzAg. Table 1 indicated beloW shoWs a time '5 over Which the 60 The green phosphor of ZnSzCu, Al activated With Ni and the blue phosphor of ZnSzAg activated With Ni have their aftergloW characteristics substantially equaliZed to the after aftergloW is reduced to 1/000, an aftergloW intensity 8 milliseconds after the excitation by the electron beam gloW characteristics of the red phosphor of Y2O2S:Eu. ceased, and an aftergloW intensity 16 milliseconds after the Therefore, if these red, green, and blue phosphors are coated excitation by the electron beam ceased. The aftergloW on the phosphor screen of the cathode-ray tube of a three intensity after elapse of 8 milliseconds corresponds to that of dimensional television system having a vertical scanning a three-dimensional television system, and the aftergloW 65 frequency of 120 HZ, then the cathode-ray tube is free of images Which Would otherWise be displayed due to persis intensity after elapse of 16 milliseconds corresponds to that tence and can display images of good quality. of an ordinary television system. 5,825,124 3 4 BRIEF DESCRIPTION OF THE DRAWINGS aftergloW curve of a green phosphor of ZnSzCu, Al activated With 5 ppm of Ni. The curves marked With 6 in FIGS. 3 and 4 and indicated by in FIG. 4 is an aftergloW curve of a green phosphor of ZnSzCu, Al activated With 10 ppm of Ni. FIG. 1 is a graph of afterglow curves of phosphors in three colors of the phosphor screen of a cathode-ray tube; FIG. 2 is a graph showing at enlarged scale of the aftergloW curves shoWn in FIG. 1; FIG. 3 is a graph of aftergloW curves of green phosphors The curves (e), overlap each other substantially fully along their entire lengths. It can be seen from the curves shoWn in FIGS. 3 and 4 that of ZnSzCu, Al activated With Ni; the aftergloW, i.e., decay, of the green phosphor of ZnSzCu, FIG. 4 is a graph shoWing at enlarged scale of the Al is reduced as the amount of activating Ni is increased. 10 aftergloW curves shoWn in FIG. 3; Table 2 shoWn beloW indicates relative luminances, FIG. 5 is a graph of aftergloW curves of blue phosphors of chromaticities, and relative decay intensities 8 milliseconds ZnSzAg activated With Ni; after removal of eXcitation, of green phosphors of ZnSzCu, FIG. 6 is a graph shoWing at enlarged scale of the Al activated With different amounts of Ni. aftergloW curves shoWn in FIG. 5; 15 FIG. 7 is a graph shoWing hoW the luminance varies With TABLE 2 the concentration of Ni added to the green phosphor of ZnSzCu, Al; and FIG. 8 is a graph shoWing hoW the luminance varies With the concentration of Ni added to the blue phosphor of 20 ZnSzAg. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Cathode-ray tubes having a ?eld frequency, i.e., a vertical 25 scanning frequency, of 120 HZ, Which is tWice the ?eld Amount of Relative added Ni luminance Relative decay intensity Chromaticity after 8 msec. (ppm) <%) X Y <%) 0 1.75 2 3.5 5 10 100 93 90 78 67 43 0.282 0.282 0.281 0.283 0.283 0.281 0.623 0.621 0.608 0.622 0.605 0.611 0.966 0.553 0.220 0.162 0.071 0.072 frequency of ordinary cathode-ray tubes, includes a phos FIG. 5 shoWs aftergloW curves of blue phosphors of phor screen having a tricolor phosphor layer composed of phosphors in three colors, i.e., a red phosphor of Y2O2S:Eu, 30 ZnSzAg activated With Ni, and FIG. 6 shoWs an enlarged a green phosphor of ZnszCu, Al, and a blue phosphor of ZnSzAg. Particularly, the green and blue phosphors emit scale the aftergloW curves shoWn in FIG. 5. The curves marked With O in FIGS. 5 and 6 and indicated by (g) in FIG. 6 is an aftergloW curve of a blue phosphor of ZnSzAg activated With 0 ppm of Ni. The curves marked With I in FIGS. 5 and 6 and indicated by (h) in FIG. 6 is an aftergloW to the persistence characteristic of the phosphor screen are governed by the colors of the aftergloW of the green and blue 35 curve of a blue phosphor of ZnSzAg activated With 1 ppm of Ni. The curves marked with O in FIGS. 5 and 6 and phosphors. Since the human eyes are highly sensitive to indicated by in FIG. 6 is an aftergloW curve of a blue differences in color, it is necessary to loWer the aftergloW, phosphor of ZnSzAg activated With 2 ppm of Ni. The curves i.e., decay, intensities of the three phosphors and also marked With X in FIGS. 5 and 6 and indicated by in FIG. equaliZe the aftergloW intensities to each other, so that the colors of the image displayed by the aftergloW Will remain 40 6 is an aftergloW curve of a blue phosphor of ZnSzAg activated With 3 ppm of Ni. The curves marked With + in unchanged. At the same time, any reduction in the lumi FIGS. 5 and 6 and indicated by (k) in FIG. 6 is an aftergloW nance of the phosphors should be avoided as much as curve of a blue phosphor of ZnSzAg activated With 5 ppm of possible. Ni. The curves marked With 6 in FIGS. 5 and 6 and indicated The phosphor screen of a cathode-ray tube according to 45 by (1) in FIG. 6 is an aftergloW curve of a blue phosphor of the present invention comprises a green phosphor of longer aftergloW, i.e., decay, than the red phosphor. Therefore, the colors of an image that remains displayed due ZnSzCu, Al activated With Ni, a blue phosphor of ZnSzAg activated With Ni, and a red phosphor of Y2O2S:Eu. Results of improved aftergloW, i.e., improved decay, of ZnSzAg activated With 10 ppm of Ni. The curves (k), (1) overlap each other substantially fully along their entire lengths. It can be seen from the curves shoWn in FIGS. 5 and 6 that green phosphors of ZnSzCu, Al activated With Ni and blue 50 the aftergloW, i.e., decay, of the blue phosphor of ZnSzAg is phosphors of ZnSzAg activated With Ni Will be described reduced as the amount of activating Ni is increased. beloW. FIG. 3 shoWs aftergloW curves of green phosphors of Table 3 shoWn beloW indicates relative luminances, ZnSzCu, Al activated With Ni, and FIG. 4 shoWs an enlarged chromaticities, and relative decay intensities 8 milliseconds scale the aftergloW curves shoWn in FIG. 3. The curves 55 after removal of eXcitation, of blue phosphors of ZnSzAg activated With different amounts of Ni. marked With O in FIGS. 3 and 4 and indicated by (a) in FIG. 4 is an aftergloW curve of a green phosphor of ZnSzCu, Al activated With 0 ppm of Ni. The curves marked With I in TABLE 3 FIGS. 3 and 4 and indicated by (b) in FIG. 4 is an aftergloW curve of a green phosphor of ZnSzCu, Al activated With 1.75 ppm of Ni. The curves marked with O in FIGS. 3 and 4 and indicated by (c) in FIG. 4 is an aftergloW curve of a green phosphor of ZnSzCu, Al activated With 2.0 ppm of Ni. The curves marked With X in FIGS. 3 and 4 and indicated by (d) in FIG. 4 is an aftergloW curve of a green phosphor of 65 ZnSzCu, Al activated With 3.5 ppm of Ni. The curves marked With + in FIGS. 3 and 4 and indicated by (e) in FIG. 4 is an Amount of Relative added Ni luminance M Relative decay intensity after 8 msec. (ppm) (‘70) X Y (‘70) 0 1 2 3 100 91 86 70 0.147 0.147 0.147 0.147 0.057 0.055 0.054 0.054 0.885 0.541 0.295 0.100 5,825,124 5 6 TABLE 3-continued As with Ni, in view of the relative luminance, the con centration of Fe or C0 added to ZnSzCu, Al and ZnSzAg should preferably be at most 10 ppm. Amount of Relative added Ni luminance Relative decay intensity (ppm) (0/0) X Y (0/0) 5 10 56 39 0.147 0.147 0.054 0.053 0.060 0.052 Chromaticity after 8 msec. Having described a preferred embodiment of the inven tion with reference to the accompanying drawings, it is to be understood that the invention is not limited to that precise embodiment and that various changes and modi?cations could be effected by one skilled in the art without departing 10 of Ni added thereto based on Table 3. What is claimed is: 1. A three-dimensional television system, comprising: 15 have their chromaticities remaining substantially unchanged. When at least 2 ppm of Ni is added to ZnSzCu, Al, the relative decay intensity of the green phosphor 8 20 reduction in the relative luminance is reduced by about 10%. The blue phosphors of ZnSzAg activated with Ni also 25 the relative decay intensity of the green phosphor 8 milli seconds after excitation is removed is reduced to 0.5% or below. When 2 ppm of Ni is added to ZnSzAg, any reduction in the relative luminance is also reduced by about 10%. 30 In view of the relative luminance, the concentration of Ni added to ZnSzCu, Al and ZnSzAg should preferably be at most 10 ppm. The green phosphor of ZnSzCu, Al activated with Ni and the blue phosphor of ZnSzAg activated with Ni have their afterglow characteristics substantially equalized to the after glow characteristics of the red phosphor of Y2O2S:Eu. Therefore, if these red, green, and blue phosphors are ing by a right eye of the viewer, wherein the ?rst and second images are vertically compressed and combined into a single transmission image; a direct viewing cathode-ray/display tube having a verti cal scanning frequency of 120 HZ by which a phosphor screen of the display tube receives the transmission have their chromaticities remaining substantially unchanged. When at least 2 ppm of Ni is added to ZnSzAg, a ?rst camera for producing a ?rst image for viewing by a left eye of a viewer; a second camera for producing a second image for view The green phosphors of ZnSzCu, Al activated with Ni milliseconds after excitation is removed is reduced to 0.5% or below. When 2 ppm of Ni is added to ZnSzCu, Al, any from the spirit or scope of the invention as de?ned in the appended claims. FIG. 7 shows how the luminance of the green phosphor of ZnSzCu, Al varies with the concentration of Ni added thereto based on Table 2, and FIG. 8 shows how the luminance of the blue phosphor of ZnSzAg varies with the concentration signal; and a phosphor layer for the phosphor screen of the display tube, the phosphor layer comprising a red phosphor of Y2O2S:EU, having a decay intensity of at most 0.5% upon elapse of 8 milliseconds after excitation is removed therefrom; a green phosphor having a host material of ZnSzCu, Al, and having a decay intensity substantially equal to said decay intensity of said red phosphor; and a blue phosphor having a host material of ZnSzAg, and having a decay intensity substantially equal to said decay intensity of said red phosphor. 2. A three-dimensional television system as claimed in claim 1, wherein said green phosphor includes a green mounted on the phosphor screen of a cathode-ray tube of a phosphor activator selected from the group consisting of Ni, three-dimensional television system having a vertical scan 40 Fe, Co, and said blue phosphor includes a blue phosphor ning frequency of 120 HZ, then the cathode-ray tube is free of images which would otherwise be displayed due to persistence and has increased resolution. activator select from the group consisting of Ni, Fe, Co. 3. A three-dimensional television system as claimed in claim 2, wherein said green phosphor activator is present in Acathode-ray tube was produced with its phosphor screen an amount of at most 10 ppm relative to said green phosphor having a green phosphor of ZnSzCu, A1 with 2 ppm of Ni 45 host material, and wherein said blue phosphor activator is added, a blue phosphor of ZnSzAg with 2 ppm of Ni added, present in an amount of at most 10 ppm relative to said blue and a red phosphor of Y2O2S:Eu. The cathode-ray tube thus phosphor host material. manufactured suffered at most a reduction of 10% or less of 4. A three-dimensional television system as claimed in white luminance, and exhibited brightness comparable to claim 3, wherein said green phosphor activator is present in equivalent ordinary cathode-ray tubes in an organoleptic 50 an amount ranging from 2 to 10 ppm relative to said green test. phosphor host material, and wherein said blue phosphor activator is present in an amount ranging from 2 to 10 ppm In the illustrated embodiment, ZnSzCu, Al and ZnSzAg are activated with Ni. However, ZnSzCu, Al and ZnSzAg relative to said blue phosphor host material. may be activated with Fe or C0, added in the same amount as Ni, for improving their afterglow characteristics. * * * * *