|Publication number||USRE32498 E|
|Application number||US 06/752,359|
|Publication date||Sep 8, 1987|
|Filing date||Jul 5, 1985|
|Priority date||Mar 27, 1981|
|Also published as||DE3211268A1, US4391885|
|Publication number||06752359, 752359, US RE32498 E, US RE32498E, US-E-RE32498, USRE32498 E, USRE32498E|
|Inventors||Yoshifumi Tomita, Hiromitsu Nakai|
|Original Assignee||Hitachi, Ltd.|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (5), Referenced by (2), Classifications (15), Legal Events (3)|
|External Links: USPTO, USPTO Assignment, Espacenet|
.Iadd.This is a reissue of application Ser. No. 361,269 filed Mar. 24, 1982, now U.S. Pat. No. 4,391,885. .Iaddend.
This invention relates to a method of manufacturing a fluorescnt screen, particularly of a multilayer construction of a cathode ray tube.
Multilayer fluorescent screen has been used in various types of cathode ray tubes. For example, in a penetration tube, two or three phosphor layers emitting light of different colors are laminated with nonluminous layers interleaved. In many cathode ray tubes, an aluminum film, called a metal back, is formed on the side of a fluorescent screen facing an electron gun structure. In such a case, a filming layer acting as a substrate is formed on the fluorescent screen.
To prepare such a multilayer construction, various techniques have been used for different purposes. These techniques, however, require complicated steps, thus requiring complicated installations, increasing manufacturing cost and decreasing yielding rate.
It is, therefore, an object of this invention to provide a novel method of manufacturing a fluorescent screen of a cathode ray tube capable of readily manufacturing a fluorescent screen of a multilayer construction.
According to this invention, there is provided a method of manufacturing a fluorescent screen of a cathode ray tube comprising the steps of.Iadd.: .Iaddend.forming a film of photosensitive substance that exhibits stickiness when exposed to light on an inner surface of a face plate of the tube; exposing the film to light to render portions thereof sticky; applying a powdery substance onto the film to cause the substance to adhere to the portions of the film rendered sticky; removing excess powder to form a film pattern of the powdery substance; causing the substance responsible for stickiness to ooze out onto the film pattern; applying another powdery substance onto the film pattern; and removing excess of .Iadd.said .Iaddend.another powdery substance, thus forming the fluorescent screen.
FIGS. 1a to 1d illustrate a preparation process of a fluorescent screen according to the present invention.
An aqueous solution of a polymer of a complex salt of diazonium salt and zinc chloride is coated on a substrate 10 of glass or the like (FIG. 1a). When the film 11 is dried and then partly irradiated with light through an apertured mask 12, zinc chloride formed as a result of photodecomposition absorbs moisture so that portions 13 of the film exposed to light becomes sticky (FIG. 1b). A dry powder is sprayed on the film in this state and excess powder is removed by compressed air to form a desired pattern 14 of the powder on the film (FIG. 1c). When the film is left .[.standstill.]. .Iadd.stationary.Iaddend., the substance responsible for stickiness or sticky liquid rises along the surfaces of the particles that constitute the film owing to capillary phenomenon, and when the film is sufficiently thin, the sticky liquid would ooze out to the top surface of the film with the result that the film itself manifests stickiness. When another type of powder is applied to such a sticky film and excess particles are blown away with air, a second film 15 of another type of the powder is formed on the first film (FIG. 1d). When the second film is sufficiently thin the sticky liquid further oozes out to the surface of the second film so that still another powder can be applied. The above preparation process can be repeated until the sticky liquid does not ooze out to prepare a multilayer film. Where a photosensitive sticky substance is coated on the substrate to a sufficient thickness and the amount of exposure light is increased, the amount of the sticky liquid increases so that it is possible to increase the number of layers. Accordingly, the number of layers can be determined as desired by varying the thickness and concentration of the photosensitive sticky substance and the amount of exposure light.
For better understanding of the invention, the following examples are given.
An aqueous solution of a photosensitive sticky substance having the following composition was coated on the inner surface of the panel glass of the color picture tube and the thickness of the film was adjusted to 0.5 to 0.8 microns with a conventional rotary spinning machine, followed by drying.
______________________________________arginic acid-polypropylene glycol ester 0.2 wt. %polyvinyl alcohol 0.06 wt. %P--dimethyl aminobenzene diazonium 3.3 wt. %chloride, zinc chloridewater balance______________________________________
After mounting a stripe shadow mask, portions of the film .Iadd.other than the portion .Iaddend.approximately corresponding to locations for three colors of green, blue and red .Iadd.stripes .Iaddend.were successively exposed to light. At this time, the position of a light .[.force.]. .Iadd.source was shifted .Iaddend.from the ordinary positions of the light source for exposure of portions at which stripes of phosphors of respective colors are to be formed, by half the distance between the positions in a direction perpendicular to the stripes. After exposure, the shadow mask was dismounted and a fine powder of graphite having a particle size of 0.2 to 0.3 microns was sprayed and excess powder was removed by compressed air, thus forming an ordinary black matrix stripe. After one minute, sticky liquid created by the previous exposure oozed out onto the .Iadd.surface of the .Iaddend.black matrix stripe. Then, a fine powder of titanium oxide having a particle size of 0.1 to 0.2 microns was applied and excess powder was removed by compressed air to form titanium oxide layer acting as a reflection layer on the graphite layer. Thereafter, the film was exposed to light in a conventional manner to form phosphor stripes of three colors .Iadd.between black matrix stripes.Iaddend.. Conventional steps were followed to complete a fluorescent screen.
This example concerns manufacture of a penetration tube. Firstly, an aqueous solution of photosensitive sticky substance having the same composition as in Example 1 was applied to the inner surface of a face plate of the tube to a thickness of 1 to 1.5 microns, the resulting film was dried and then uniformly exposed to light. A powder of phosphor acting as a blue phosphor and consisting of zinc sulfide and silver and having a particle size of about 0.1 micron was sprayed to a thickness of about 0.9 microns and excess powder was removed by compressed air. The assembly was left standstill for about one minute to cause the sticky liquid to ooze out. Then, a powder of silica having a particle size of about 0.05 microns was applied to a thickness of about 0.25 microns and excess powder was removed by compressed air to form silica films acting as barriers for increasing the potential difference between phosphor layers. The assembly was left .[.standstill.]. .Iadd.stationary .Iaddend.for one minute to cause the sticky liquid to ooze out. Then, a powder of green phosphor consisting of zinc silicate and manganese was applied to a thickness of about 0.25 microns and then developed. The assembly was left .[.standstill.]. .Iadd.stationary .Iaddend.for 30 seconds, and then in the same manner as described above, a powder of silica was applied to a thickness of about 0.7 microns to form a silica film. Then, the assembly was left standstill for one minute, and a powder of red phosphor having a particle size of 0.1 micron and consisting of silicates of magnesium, cadmium and zinc, and manganese was applied to a thickness of about 0.5 microns to form a multilayer construction, followed by predetermined steps to obtain a fluorescent screen.
An aqueous solution of the photosensitive sticky substance, the same as that of Example 1, was coated to a thickness of about 0.5 to 0.6 microns on the inner surface of the face plate of a monochromatic cathode ray tube and then dried. After uniformly exposing the resulting film to light, a powder of white phosphor having a particle size of about 7 to 8 microns and consisting of a mixture of zinc sulfide-silver, zinc sulfide-copper, and aluminam was sprayed to a thickness of about 15 to 20 microns, and excess powder was removed with compressed air. After the assembly was left .[.standstill.]. .Iadd.stationary .Iaddend.for two minutes, a fine powder of .[.isobuthyl.]. .Iadd.isobutyl .Iaddend.methacrylate resin having a particle size of about 0.05 microns was applied to a thickness of about 5 microns and the resulting film was then developed. Thereafter, the face plate was heated to 85° C. to fuse together the particles of the resin for forming a continuous film acting as a filming layer on the phosphor film, followed by predetermined steps to obtain a fluorescent screen.
It should be understood that the foregoing examples show only few examples of the method of this invention for preparing a fluorescent screen of a multilayer construction, and that various types of fluorescent screens can be prepared by adjusting the quantity of the sticky liquid by varying the quantity of the applied photosensitive sticky substance and the quantity of exposure light, or by changing the combination of the powdery substances. For example, the filming layer described in Example 3 can also be applied following the steps described in Examples 1 and 2.
As described above, according to the method of manufacturing a fluorescent screen of a cathode ray tube of this invention, a film of photosensitive sticky substance is exposed to light to render it sticky, then powders of various substances are applied to the sticky film, and excess powders are removed to develope. After the sticky liquid has oozed out to the surface of the film, another powder is applied again and then developed. In this manner, a multilayer fluorescent screen having any desired number of layers and consisting of different materials can readily be prepared until the sticky liquid does not ooze out any more.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US4247612 *||Aug 8, 1979||Jan 27, 1981||Hitachi, Ltd.||Method of forming fluorescent screens of color picture tubes|
|US4269918 *||Aug 3, 1979||May 26, 1981||Hitachi, Ltd.||Process for forming patternwise coated powder layer|
|US4273842 *||Apr 11, 1978||Jun 16, 1981||Hitachi, Ltd.||Process for forming patternwise coated powder layer|
|US4318971 *||Feb 12, 1981||Mar 9, 1982||Hitachi, Ltd.||Method of forming fluorescent screen of color picture tube|
|US4331752 *||Sep 8, 1980||May 25, 1982||Hitachi, Ltd.||Method of forming fluorescent screens of color picture tubes|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US7592639 *||Oct 25, 2006||Sep 22, 2009||Panasonic Corporation||Light-emitting semiconductor device, light-emitting system and method for fabricating light-emitting semiconductor device|
|US20070046169 *||Oct 25, 2006||Mar 1, 2007||Matsushita Electric Industrial Co., Ltd.||Light-emitting semiconductor device, light-emitting system and method for fabricating light-emitting semiconductor device|
|U.S. Classification||430/28, 427/516, 427/68, 427/557, 427/64|
|International Classification||H01J9/227, G03F7/28, H01J9/22, H01J29/28|
|Cooperative Classification||G03F7/28, H01J9/2271, H01J29/28|
|European Classification||H01J9/227B, G03F7/28, H01J29/28|
|Dec 12, 1990||FPAY||Fee payment|
Year of fee payment: 8
|Feb 7, 1995||REMI||Maintenance fee reminder mailed|
|Jul 2, 1995||LAPS||Lapse for failure to pay maintenance fees|