WO1999012180A1

WO1999012180A1 - SOLUTION FOR MAKING A RESIN FILM AND ITS APPLICATION AT SCREENS OF CRTs

Info

Publication number: WO1999012180A1
Application number: PCT/KR1997/000287
Authority: WO
Inventors: Sang Youl Yoon; Ho Seok Shon
Original assignee: Orion Electric Co., Ltd.
Priority date: 1997-08-30
Filing date: 1997-12-31
Publication date: 1999-03-11
Also published as: KR19990020175A; KR100267174B1

Abstract

A solution for making a resin film contains at most 5 % by weight, preferably 1 % by weight, of α-carbon methyl group polymer. By the solution, the combustion temperature can be lowered down, and the resin film can be completely volatilized without upward swelling of the aluminum thin film during the burning or baking step owing to the solution formed by the α-carbon methyl group polymer. Specifically, also in the method for dry electrophotographically manufacturing a screen of a CRT, the conductive layer, the photo-conductive layer, and the resin film can be completely volatilized without the upward swelling and unfastening of the aluminum thin film during the burning step in a frit furnace for sealed-assembling the panel and the funnel, so that the plane reflectivity of the aluminum thin film is improved and thus the picture quality of the CRT is greatly improved.

Description

TITLE OF THE INVENTION

SOLUTION FOR MAKING A RESIN FILM AND ITS APPLICATION AT SCREENS OF CRTs

FIELD OF THE INVENTION

The present invention relates to a solution for making a resin film, a method for manufacturing a screen of a CRT using the solution and a CRT manufactured by the method, and more particularly to a solution for making a resin film, by which an aluminum thin film having an improved effective plane of reflection can be formed.

BACKGROUND OF THE INVENTION

Referring to FIG. 1 , a color CRT 10 generally comprises an evacuated glass envelope consisting of a panel 12, a funnel 13 sealed to the panel 12 and a tubular neck 14 connected by the funnel 13, an electron gun 11 centrally mounted within the neck 14, and a shadow mask 16 removably mounted to an inner sidewall of the panel 12. A three color phosphor screen is formed on the inner surface of a display window or faceplate 18 of the panel 12.

The electron gun 11 generates three electron beams 19a or 19b, said beams being directed along convergent paths through the shadow mask 16 to the screen 20 by means of several lenses of the gun and a high positive voltage applied through an anode button 15 and being deflected by a deflection yoke 17 so as to scan over the screen 20 through apertures or slits 16a formed in the shadow mask 16.

In the color CRT 10, the phosphor screen 20, which is formed on the inner surface of the faceplate 18, comprises an array of three phosphor elements R, G and B of three different emission colors arranged in a cyclic order of a predetermined structure of multiple-stripe or multiple-dot shape and a matrix of light-absorptive material 21 surrounding the phosphor elements R, G and B, as shown in FIG. 2.

A thin film of aluminum 22 or electro-conductive layer, overlying the screen 20 in order to provide a means for applying the uniform potential applied through the anode button 15 to the screen 20, increases the brightness of the phosphor screen, prevents ions from damaging the phosphor screen and prevents the potential of the phosphor screen from decreasing. And also, a resin film 22' such as lacquer is applied to the phosphor screen 20 before forming the aluminum thin film 22, so as to enhance the flatness and reflectivity of the aluminum thin film 22. The resin film 22' must be burned to volatilize after the aluminum thin film 22 is formed, so as to improve the life of the tube. In a photolithographic wet process, which is well known as a prior art process for forming the phosphor screen, a slurry of a photosensitive binder and phosphor particles is coated on the inner surface of the faceplate. It does not meet the higher resolution demands and requires a lot of complicated processing steps and a lot of manufacturing equipments with the use of a large quantity of clean water, thereby necessitating high cost in manufacturing the phosphor screen. In addition, it discharges a large quantity of effluent such as waste water, phosphor elements, 6th chrome sensitizer, etc.

To solve or alleviate the above problems, an improved process of electro-photographically manufacturing the screen utilizing dry-powdered phosphor particles is developed.

U.S. Pat. No. 4,921,767, issued to Datta at al . on May 1, 1990, discloses the improved method of electrophotographically manufacturing the phosphor screen assembly using dry-powdered phosphor particles through a series of steps represented in FIGs. 3A to 3E, as is briefly explained in the following.

After the panel 12 is washed, an electro-conductive layer 32 is coated on the inner surface of the faceplate 18 of the panel 12 and the photo-conductive layer 34 is coated thereon, as shown in FIG. 3A. Conventionally, the electro-conductive layer 32 is made from an inorganic conductive material such as tin oxide or indium oxide, or their mixture, and preferably, from a volatilizable organic conductive material such as a pσlyelectrolyte commerc ia l ly known a s po lybrene ( 1 , 5-dimethy-l , 5-diaza-undecamethylene polymethobromide, hexadimethrine bromide), available from Aldrich Chemical Co .

The polybrene is applied to the inner surface of the faceplate 18 in an aqueous solution containing about 10 percent by weight of propanol and about 10 percent by weight of a water-soluble adhesion-promoting polymer (poly vinyl alcohol, polyacrylic acid, polyamides and the like), and the coated solution is dried to form the conductive layer 32 having a thickness from about 1 to 2 microns and a surface resistivity of less than about 10⁸ Ω/D (ohms per square unit) .

The photo-conductive layer 34 is formed by coating the conductive layer 32 with a photo-conductive solution comprising a volatilizable organic polymeric material, a suitable photo-conductive dye and a solvent. The polymeric material is an organic polymer such as polyvinyl carbazole, or an organic monomer such as n-ethyl carbazole, n-vinyl carbazole or tetraphenylbutatriene dissolved in a polymeric binder such as polymethylmethacrylate or polypropylene carbonate. The photo-conductive composition contains from about 0.1 to 0.4 percent by weight such dyes as crystal violet, chloridine blue, rhoda ine EG and the like, which are sensitive to the visible rays, preferably rays having wavelength of from about 400 to 700 nm. The solvent for the photo-conductive composition is an organic material such as chlorobenzene or cyclopentanone and the like which will produce as little contamination as possible on the conductive layer 32. The photo-conductive layer 34 is formed to have a thickness from about 2 to 6 microns.

FIG. 3B schematically illustrates a charging step, wherein the photo-conductive layer 34 overlying the electro-conductive layer 32 is positively charged in a dark environment by a conventional positive corona discharger 36. As shown, the charger or charging electrode of the discharger 36 is positively applied with direct current while the negative electrode of the discharger 36 is connected to the electro-conductive layer 32 and grounded. The charging electrode of the discharger 36 travels across the layer 34 and charges it with a positive voltage in the range from +200 to +700 volt.

FIG. 3C schematically shows an exposure step, wherein the charged photo-conductive layer 34 is exposed through a shadow mask 16 by a xenon flash lamp 35 having a lens system 35' in the dark environment. In this step, the shadow mask 16 is installed on the panel 12 and the electro-conductive layer 32 is grounded. When the xenon flash lamp 35 is switched on to shed light on the charged photo-conductive layer 34 through the lens system 35' and the shadow mask 16, portions of the photo-conductive layer

34 corresponding to apertures or slits 16a of the shadow mask 16 are exposed to the light. Then, the positive charges of the exposed areas are discharged through the grounded conductive layer 32 and the charges of the unexposed areas remain in the photo-conductive layer 34, thus establishing a latent charge image in a predetermined array structure, as shown in FIG. 3C. In order to exactly attach light-absorptive materials, it is preferred that the xenon flash lamp 35 travels along three positions while coinciding with three different incident angles of the three electron beams. FIG. 3D schematically shows a developing step which utilizes a developing container 35" containing dry- powdered light-absorptive or phosphor particles and carrier beads for producing static electricity by coming into contact with the dry-powdered particles. Preferably, the carrier beads are so mixed as to charge the light- absorptive particles with negative electric charges and the phosphor powders with positive electric charges when they come into contact with the dry-powdered particles .

In this step, the panel 12, from which the shadow mask 16 is removed, is put on the developing container 35" containing the dry-powdered particles, so that the photo- conductive layer 34 can come into contact with the dry-powdered particles. In this case, the negatively charged light-absorptive particles are attached to the positively charged unexposed areas of the photo-conductive layer 34 by electric attraction, while the positively charged phosphor particles are repulsed by the positively charged unexposed areas but attached by reversal developing to the exposed areas of the photo-conductive layer 34 from which the positive electric charges are discharged.

FIG. 3E schematically represents a fixing step by means of infrared radiation. In this step, the light-absorptive and phosphor particles attached in the above developing step are fixed together and onto the photo-conductive layer 34. Therefore, the dry-powdered particles includes proper polymer components which may be melted by heat and have proper adhesion.

The steps of charging, exposing, developing and fixing are repeated for the three different phosphor particles. Moreover, the same process of the above steps can be repeated also for the black matrix particles before or after the three different phosphor particles are formed.

After the three different phosphor particles and the black matrix particles are formed through the above process, a lacquer film is formed through a lacquering step and an aluminum thin film is formed through an aluminizing step respectively by a conventional method. Thereafter, the faceplate panel 12 is baked in air at a temperature of 425 °C, for about 30 minutes to drive off the volatilizable constituents such as the organic solvents from the conductive layer 32, the photo- conductive layer 34, the phosphor elements and the lacquer film, thereby forming a screen array 20 of light-absorptive material 21 and three phosphor elements R, G and B in FIG. 2. The conventional method of electro-photographically manufacturing the phosphor screen assembly using dry-powdered phosphor particles as described above has one problem that it requires dark environment during all the steps until the fixing step after the photo-conductive layer is formed, because the photo-conductive layer is sensitive to the visual light. Also, the fixing step of FIG. 3E is still necessary even after the developing step. To overcome this problem, the applicant proposed a method of forming the photo-conductive layer using a photo-conductive solution responsive to the ultraviolet rays .

The solution for the photo-conductive layer 34 responsive to the ultraviolet rays, for example, may contain: an electron donor material, such as about 0.01 to 1 percent by weight of bis-1, 4-dimethyl phenyl (-1,4- diphenyl (butatriene) ) or 2 to 5 percent by weight of tetraphenyl ethylene (TPE); an electron acceptor material, such as about 0.01 to 1 percent by weight of at least one of trinitro-fluorenone (TNF) and ethyl anthraquinone (EAQ); a polymeric binder, such as 1 to 30 percent by weight polystyrene; and a solvent such as the remaining percent by weight of toluene or xylene. As the polymeric binder, poly(α-methylstyrene) (PαMS), polymethylmethacrylate (PMMA), and polystyrene- oxazoline copolymer (PS-OX) may be employed instead of the polystyrene.

However, in the fixing step of FIG. 3E for fixing the phosphor particles, the developed phosphor particles P come down into the photo-conductive layer 34 as shown in FIGs. 4A and 4B, since the photo-conductive layer 34 is melt. After that, when the resin film 22' has been formed, the surface of the resin film 22' becomes smooth as the inner surface of the panel 12. Then, gas generated from the conductive layer 32, the photo-conductive layer 34 and the resin film 22' during the burning step in a frit furnace for sealed-assembling the panel and the funnel or during the baking step applies an over-pressure to the aluminum thin film 22, so that the aluminum thin film 22 becomes swollen and unfastened upward from the screen easily. In result, the plane reflectivity of the aluminum thin film 22 is deteriorated, and moreover the volatile resin remains therein to deteriorate the picture quality.

The present invention has been made to overcome the above described problems, and therefore it is an object of the present invention to provide a solution for making a resin film, a method for manufacturing a screen of a CRT using the solution and a CRT manufactured by the method, in which a resin film in a wet slurry method or a dry electro-photographical method is completely volatilized at a low temperature while the conductive layer or the photo- conductive layer in the dry electro-photographical method is burned at relatively higher temperature, so as to prevent the concurrent discharge of the entire gas and the swelling up of the aluminum thin film.

SUMMARY OF THE INVENTION To achieve the above objects, the present invention provides a solution for making a resin film in a cathode ray tube, the cathode ray tube having a phosphor screen formed on an inner surface of a faceplate, the phosphor screen comprising: an array of three phosphor elements of three different emission colors arranged in a cyclic order of a predetermined structure of multiple-stripe or multiple-dot shape and a matrix of light-absorptive material surrounding the phosphor elements; a resin film such as a lacquer film formed on the light-absorptive material and the phosphor elements using the solution; and an aluminum thin film formed on the resin film just after the resin film is formed, the resin film enhancing a flatness and a reflectivity of the aluminum thin film, the aluminum thin film functioning as a conductive film and a plane of reflection, wherein the solution comprises at most 5 % by weight, preferably 1 % by weight, of α-carbon methyl group polymer.

The present invention further provides a cathode ray tube having a phosphor screen formed on an inner surface of a faceplate, the phosphor screen comprising: an array of three phosphor elements of three different emission colors arranged in a cyclic order of a predetermined structure of multiple-stripe or multiple-dot shape and a matrix of light-absorptive material surrounding the phosphor elements; a resin film such as a lacquer film formed on the light-absorptive material and the phosphor elements, the resin film being coated with a solution containing at most 5 % by weight, preferably 1 % by weight, of α-carbon methyl group polymer; and an aluminum thin film formed on the resin film, the aluminum thin film functioning as a conductive film and a plane of reflection, the aluminum thin film being fixed without swelling up on volatilizing volatilizable constituents from the resin film by heat.

It is preferred that at least one of the phosphor elements and the light-absorptive material is manufactured by a dry-electro-photographically- manufacturing process comprising the steps of: forming a volatile photo-conductive layer on the volatile conductive layer coated on an inner surface of a panel, the volatile photo-conductive layer containing a material responsive to visible rays or ultraviolet rays; charging the volatile photo-conductive layer with uniform electrostatic charges; selectively exposing the volatile photo-conductive layer through a shadow mask to a light source; and developing the photo-conductive layer by charging said at least one of the phosphor elements and the light- absorptive material to be attached to the photo-conductive layer; wherein, in the volatilizing step, the volatilizable constituents are volatilized from the conductive layer, the photo-conductive layer and the resin film by heat.

More preferably, the α-carbon methyl group polymer is selected from at least one of polyalphamethylstyrene(PαMS) , polymethylmethacrylate (PMMA) , polyhydroxyethylmethacrylate ( PHEMA ) , polyisobutylmethacrylate(PIBMA) , and their mixture, and also, the solution may comprise a small quantity of plasticizer to form a film if necessary.

As described above, by forming the resin film with the solution such as lacquer containing at most 5 % by weight, preferably 1 % by weight, of α-carbon methyl group polymer according to the present invention, which experiences the perfect combustion at about 300 °C and as well has a great unzipping effect. Therefore, the gas is generated gradually at a low speed and is completely discharged without swelling up the aluminum thin film. Further, in case of dry electro-photographical method, since the combustion temperature is lower than 400 °C which is the combustion temperature of the photo- conductive layer, the combustion gas can be easily discharged from the photo-conductive layer through a path through which the resin film is discharged after burned.

BRIEF DESCRIPTION OF THE DRAWINGS

The above object, and other features and advantages of the present invention will become more apparent by describing in detail preferred embodiments thereof with reference to the attached drawings, in which:

FIG. 1 is a plan view partially in axial section of a color cathode-ray tube; FIG. 2 is an enlarged partial sectional view of a screen assembly of the tube shown in FIG.l;

FIGs . 3A through 3E are schematic sectional views for showing various steps in the method for dry electro- photographically manufacturing the screen using the solution of the present invention;

FIGs . 4A and 4B are schematic views for showing the problems of the prior art; and

FIG. 5 is a graph for showing the burning process of the resin film and the photo-conductive layer according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

When a screen of a color CRT is manufactured, a resin film 22' such as a lacquer film is formed between an aluminum thin film 22 and a light-absorptive material or black matrix particles 21 together with the phosphor particles R, G and B, so as to enhance the flatness and reflectivity of the aluminum thin film 22, before the aluminum thin film 22 is formed. The resin film 22' is burned to volatilize in a frit furnace for sealed- assembling the panel and the funnel with each other, so as to eliminate the possibility of generation of gas after the aluminum thin film 22 is formed, to thereby improve the life of the CRT. The solution for making the resin film 22' according to the present invention is formed by at most 5 % by weight, preferably 1 % by weight, of α-carbon methyl group polymer dissolved by solvent. The α-carbon methyl group polymer may be, as an example, selected from at least one of polyalpha- methylstyrene(PαMS) , polymethylmethacrylate (PMMA), polyhydroxyethylmethacrylate (PHEMA), polyisobutyl- methacrylate (PIBMA) , and their mixture. As shown in FIG. 5, since the polyalphamethylstyrene experiences the perfect combustion at 300 °C and as well has a great unzipping effect, it can make the gas be discharged gradually at a low speed and completely without swelling up the aluminum thin film 22. Further, in case of the polymethylmethacrylate (PMMA) for forming the photo-conductive layer 34 in the method for dry-electro-photographically manufacturing a screen of a CRT, since polymethylmethacrylate (PMMA) experiences the perfect combustion at 440 °C, the photo-conductive layer 34 begins to be burned after the perfect combustion of the polyalphamethylstyrene (PαMS) of the above resin film 22', so as to prevent the gas from being discharged quickly all together. Therefore, the swelling of the aluminum thin film 22 is further effectively prevented and the combustion gas can be easily discharged from the photo- conductive layer 34 through a path through which the resin film 22' is discharged after burned.

As described above, since the present invention employs, as the solid composition of the resin film 22', a polymer which can be burned at a low temperature and has a great unzipping effect, a complete combustion and volatilization of the resin film 22' is possible. In the method for dry electro-photographically manufacturing a screen of a CRT, since the temperature of the resin film 22' is lower than that of the photo-conductive layer 34 and thus the gas can be discharged with time difference, the gas can be discharged without upward swelling or unfastening of the aluminum thin film 22.

It is preferred according to the present invention that, a predetermined array of the light-absorptive material 21 is formed on an inner surface of the panel 12, three phosphor elements R, G and B arranged in a cyclic order of a predetermined structure of multiple-stripe or multiple-dot are formed at an inner surface of the faceplate 18 by the method of dry electro-photographically manufacturing the phosphor screen assembly through a series of steps represented in FIGs. 3A to 3E. That is, as shown in FIGs. 3A to 3E, the volatile photo-conductive layer 34 containing a material responsive to the visible rays or the ultraviolet rays is formed on the volatile conductive layer 32 coated on the inner surface of the panel 12 in which a light-absorptive material 21 is formed by the conventional slurry method. Thereafter, the photo- conductive layer 34 is charged with uniform electrostatic charges, and then is selectively exposed to the visible rays or the ultraviolet rays through a shadow mask. Then, the phosphor elements R, G, and B are attached to the exposed area of the photo-conductive layer 34 one by one, and then developed to complete the formation of the phosphor elements on the screen. Thereafter, the resin film 22' is formed on the inner surface of the light-absorptive material 21 and the three phosphor elements R, G and B with the resin-film-making solution such as lacquer containing at most 5 % by weight, preferably 1 % by weight, of α-carbon methyl group polymer as described above, and then an aluminum thin film 22 which functions as a conductive film and a plane of reflection is formed on the resin film 22'. Thereafter, the panel 12 with the resin film 22' and the aluminum thin film 22 is subjected to a baking step in order to completely volatilize by heat the volatile ingredient from the conductive layer 32, the photo-conductive layer 34, and the resin film 22' with maintaining the aluminum thin film 22.

In the solution for making the resin film of a CRT according to the present invention, the quantity of the solid composition may be less than 50% of that of the conventional solution for making a resin film of a CRT. That is, the α-carbon methyl group polymer may be at most 0.5 % by weight simultaneously while a small quantity of plasticizer may be added to help formation of the film in case where it is difficult to form the film. Especially, when the resin film 22' is formed by the wet slurry method, since it is difficult to form the film by only at most 0.5 % by weight of the solid composition, the addition of a small quantity of plasticizer is necessary. The plasticizer may be dibutylphthalate (DBP), dioctylphthalate (DOP), etc. By utilizing the α-carbon methyl group polymer at the same time with reducing the quantity of the α-carbon methyl group polymer, the generation of the volatile gas can be more effectively reduced and proceeded with time variance. Therefore, the resin film 22' is completely volatilized during the burning step in a frit furnace for sealed-assembling the panel and the funnel or the baking step, and the swelling up or unfastening of the aluminum thin film 22 is prevented.

Moreover, in the developing step, instead of being charged by such contact as shown in FIG. 3D, the powdered particles may be charged by a contact with a pipe in the course of being supplied, or charged by a corona discharge just before being sprayed by a spray coater.

The fixing step as shown in FIG. 3E may employ a vapor swelling method wherein the fixing is performed by a contact with a solvent vapor such as acetone and methyl isobutyl ketone, or a spraying method wherein an electrostatic solution spray gun sprays a mixture of at two kinds among methyl isobutyl ketone, TCE, toluene, and xylene of the petrolium group on the developed powdered- particles of red, green, and blue. Otherwise, the fixing step may be omitted partly or totally.

As apparent from the above description, by the construction and the function of the solution for making a resin film, the method for manufacturing a screen of a CRT using the solution and the CRT manufactured by the method according to the present invention, the unzipping effect can be increased, the combustion temperature can be lowered down, and the resin film 22' can be completely volatilized without upward swelling of the aluminum thin film 22 during the burning or baking step owing to the solution formed by the α-carbon methyl group polymer. Specifically, also in the method for dry electrophotographically manufacturing a screen of a CRT, the conductive layer, the photo-conductive layer, and the resin film can be completely volatilized without the upward swelling and unfastening of the aluminum thin film during the burning step in a frit furnace for sealed- assembling the panel and the funnel, so that the plane reflectivity of the aluminum thin film is improved and thus the picture quality of the CRT is greatly improved. While the present invention has been particularly shown and described with reference to the particular embodiment thereof, it will be understood by those skilled in the art that various changes in form and details may be effected therein without departing from the spirit and scope of the invention as defined by the appended claims .

Claims

What is claimed is :

1. A solution for making a resin film in a cathode ray tube, the cathode ray tube having a phosphor screen formed on an inner surface of a faceplate, the phosphor screen comprising: an array of three phosphor elements of three different emission colors arranged in a cyclic order of a predetermined structure of multiple-stripe or multiple-dot shape and a matrix of light-absorptive material surrounding the phosphor elements; a resin film such as lacquer formed on the light-absorptive material and the phosphor elements using the solution; and an aluminum thin film formed on the resin film just after the resin film is formed, the resin film enhancing a flatness and a reflectivity of the aluminum thin film, the aluminum thin film functioning as a conductive film and a plane of reflection, wherein the solution comprises at most 5 % by weight, preferably 1 % by weight, of ╬▒-carbon methyl group polymer.

2. A solution for making a resin film in a cathode ray tube, as claimed in claim 1, wherein the ╬▒-carbon methyl group polymer is selected from at least one of polyalphamethylstyrene, polymethylmethacrylate, polyhydroxyethylmethacrylate, polyisobutylmethacrylate, and their mixture.

3. A solution for making a resin film in a cathode ray tube, as claimed in claims 1 or 2, wherein the solution comprises at most 0.5 % by weight of the ╬▒-carbon methyl group polymer together with a small quantity of plasticizer.

4. A method for electro-photographically manufacturing a screen of a CRT utilizing dry-powdered phosphor particles, the screen including an array of three phosphor elements of three different emission colors arranged in a cyclic order of a predetermined structure of multiple-stripe or multiple-dot shape and a matrix of light-absorptive material surrounding the phosphor elements, the method comprising the steps of: forming a resin film on the light-absorptive material and the phosphor elements with a resin solution such as lacquer containing at most 5 % by weight, preferably 1 % by weight, of ╬▒-carbon methyl group polymer; forming an aluminum thin film on the resin film, the aluminum thin film functioning as a conductive film and a plane of reflection; and volatilizing volatilizable constituents from the resin film by heat.

5. A method as claimed in claim 4, at least one of the phosphor elements and the light-absorptive material being manufactured by a dry-electro-photographically- cathode-ray-tube-manufacturing method comprising the steps of: forming a volatile photo-conductive layer on the volatile conductive layer coated on an inner surface of a panel, the volatile photo-conductive layer containing a material responsive to visible rays or ultraviolet rays; charging the volatile photo-conductive layer with uniform electrostatic charges; selectively exposing the volatile photo-conductive layer through a shadow mask to a light source; and developing the photo-conductive layer by charging said at least one of the phosphor elements and the light- absorptive material to be attached to the photo-conductive layer, wherein, in the volatilizing step, the volatilizable constituents are volatilized from the conductive layer, the photo-conductive layer and the resin film by heat.

6. A cathode ray tube having a phosphor screen formed on an inner surface of a faceplate, the phosphor screen comprising: an array of three phosphor elements of three different emission colors arranged in a cyclic order of a predetermined structure of multiple-stripe or multiple-dot shape and a matrix of light-absorptive material surrounding the phosphor elements; a resin film such as a lacquer film formed on the light-absorptive material and the phosphor elements, the resin film being coated with a solution containing at most 5 % by weight, preferably 1 % by weight, of ╬▒-carbon methyl group polymer; and an aluminum thin film formed on the resin film, the aluminum thin film functioning as a conductive film and a plane of reflection, the aluminum thin film being fixed without swelling up on volatilizing volatilizable constituents of the resin film by heat.