KR100202866B1 - Manufacturing method of electrophotographic screen of crt - Google Patents

Abstract

In order to uniformly form the fluorescent film, a method of manufacturing a screen by uniformly charging the photoconductive film is provided. (1) forming a volatile conductive film on the inner surface of the panel; (2) a secondary coating step of forming an insulating film for electrical insulation on the conductive film; (3) a tertiary coating step of forming a volatile first photoconductive film containing a substance sensitive to light rays of a first wavelength region on the insulating film; (4) forming a volatile second photoconductive film on the first photoconductive film containing a material that is sensitive to light in a second wavelength region; (5) Applying a -DC electrode to the second photoconductive film and applying a + DC electrode to the conductive film while exposing the second wavelength region of light to the second photoconductive film over the entire surface to provide a uniform electrostatic charge. A charging step of charging the two photoconductive films; (6) an exposure step of exposing through a shadow mask with light rays of a first wavelength band so as to selectively move the electrostatic charge of the second photoconductive film to the first photoconductive film; And (7) a developing step of attaching the charged fine powder to any one of an exposed portion of the first photoconductive film to which the electrostatic charge is selectively moved in the exposure step 6 and the remaining non-exposed portion. As a result, not only a discharge device such as a corona discharge device is required, but the charging can be made uniform without the need for adjusting complicated discharge conditions, the process can be simplified, and the coating thickness, size, shape, etc. of the phosphor can be made uniform. There is.

Description

Method for manufacturing electrophotographic screen of cathode ray tube

1 is a schematic front view in partial cross section of a color cathode ray tube;

FIG. 2 (a) is a partially enlarged sectional view showing the screen configuration of the cathode ray tube of FIG.

3 (a) to 3 (e) are schematic explanatory diagrams showing a dry electrophotographic screen manufacturing process for manufacturing a screen of a cathode ray tube using a discharge device.

4 is a process chart for producing a color cathode ray tube by a conventional dry electrophotographic screen manufacturing method.

FIG. 5 (a) and (b) show a conventional photoconductive film discharging apparatus for screen manufacturing of a cathode ray tube used in FIG. 3 (b), and (a) is a schematic cross-sectional view illustrating a relationship with a panel. (b) is a detailed sectional view of the discharge electrode which shows the structure of a discharge electrode.

Figure 6 (a) to (f) is a partial cross-sectional view of the panel face plate for explaining the main process of the screen manufacturing method according to the present invention.

* Explanation of symbols for main parts of the drawings

10 cathode ray tube (CRT) 11 electron gun

12: panel 13: funnel

14 neck 15 anode button

16: shadow mask 17: deflection yoke

18: panel face plate 19a, 19b: electron beam

20: fluorescent screen (screen) 21: light absorbing material

22: aluminum thin film layer 32: conductive film

34: photoelectric film 36, 50: discharge device

38: light source (visible light) 40: lens

42: developing container 51: discharge electrode

51a: tip 52: support metal piece

53: insulation plate 54: insulator

62: conductive film 64: insulating film

66: first photoconductive film 68: second photoconductive film or conductive film

The present invention relates to a method for producing an electrophotographic screen of a cathode ray tube, and more particularly, to a method of uniformly charging a photoconductive film in order to form a fluorescent film uniformly.

In general, the cathode ray tube, as shown in FIG. 1, has a vacuum bulb divided into a panel 12, a funnel 13 and a neck 14, and the neck 14 thereof. An electron gun 11 mounted therein and a shadow mask 16 mounted on the side wall of the panel 12 are provided.

A fluorescent surface 20 is formed on the inner surface of the face plate 18 of the panel 12, and the electron beams 19a and 19b emitted from the electron gun 11 are focused and accelerated by various lens systems, and the anode button 15 It is greatly accelerated by the high voltage applied through the deflection yoke (17) and deflected by the deflection yoke (17) and passed through the apertures or slits (16a) of the shadow mask (16) to the fluorescent surface (20).

The fluorescent surface 20 is formed on the back surface of the face plate 18. In the case of the color, as shown in FIG. 2, a plurality of stripe or dot-shaped phosphors R, G, and B in a constant array structure are shown. ) And a light absorbing material such as a black coating between the respective phosphors. In addition, the rear surface is formed with an aluminum thin film layer 22 as a conductive film layer, which serves to increase the luminance of the fluorescent surface, to prevent ion damage of the fluorescent surface, and to prevent the potential drop of the fluorescent surface. Although not shown, a resin such as a lacquer is applied between the fluorescent surface 20 and the conductive film layer 22 in order to improve the plan view and reflectance of the aluminum thin film layer 22.

According to the conventional photolithographic wet process or the wet slurry method, the fluorescent surface 20 is dried by applying a slurry in which one phosphor is mixed with a photoresist aqueous solution to the inner surface of the panel. , (2) put on a shadow mask and expose it to ultraviolet light to harden the photosensitive material at the place of the phosphor, and (3) spray water at high pressure on the panel to wash and dry unnecessary parts of the phosphor three times. Apply three phosphors.

Therefore, this method requires the use of a slurry, and all of the phosphors need to be coated on the parts that are not needed, and only most of the parts need to be washed away, thus not only satisfying the demands of high definition, but also complicated manufacturing process and manufacturing equipment, resulting in large manufacturing costs. In addition, there are various problems such as consumption of large quantities of clean water, generation of waste water, phosphorus emissions, and hexavalent chromium photoreceptor discharge. Recently, an electrophotographic screen manufacturing method has been developed that improves the wet photolithography. In this electrophotographic manufacturing method, the wet still has the above-mentioned problems, and the dry manufacturing method has the problems described above. It was considerably resolved. In other words, the process is dramatically simplified compared to the conventional wet method, the energy and resource saving effect of the process shortening is great and productivity is expected to be greatly improved. In addition, since no water is used in the manufacturing process of the fluorescent film, it can be used for phosphors that are sensitive or soluble in water. This broadening of the choice of phosphor is also an important advantage of this dry method.

Such dry electrophotographic screen manufacturing methods are disclosed in US Pat. Nos. 4,921,727, 4,921,767, 5,012,155, 5,083,959, and 5,093,217, of which 4,921,767 (May 1, 1990). Patented) is briefly described as follows.

3 (a) to (e) schematically show each basic process of the dry electrophotographic screen manufacturing method.

The panel 12 is cleaned in various ways on its inner surface prior to entering the screening process. Then, the inner surface of the panel 18 of the panel is coated with an electrically conductive film 32, as shown in FIG. As the compound used in the conductive film 32, inorganic conductive materials such as tin, indium oxide, or mixtures thereof are disclosed. The raw material of the volatile conductive film is Aldrich Chemical Co. trade name Polybrene: 1,5-dimethyl-1,5-diaza-undicamethylene polymethobromide, hexadimethrin bromide) is disclosed. The polybrine is applied in an aqueous solution containing about 10% by weight of propanol and 10% by weight of water-soluble adhesive polymers (polyvinyl alcohol, polyacrylic acid, polyamide, etc.) and dried to obtain 10 ⁸ Ω /? (Ohms per square unit). A conductive film 32 having a surface resistance of 1 m or less and a thickness of about 1-2 mu m is formed. The photoconductive film 34 coated on the conductive film 32 is n-ethyl carbazole or n dissolved in a volatile organic polymer (polyvinylcarbazole) or a polymer binder (polymethylmethacrylate or polypropylene carbonate). A coating liquid comprising an organic monomer such as -vinylcarbazole or tetraphenylbutatriene, a suitable photoconductive dye and a solvent is disclosed. Its photoconductive dye reacts to visible light (preferably 400-700nm wavelength), such as crystal violet, chloridine blue and rhodamine EG. It is disclosed to contain about 0.1 to 0.4% by weight. As the solvent, organic substances such as chlorobenzene and cyclopentanone that do not contaminate the conductive film 32 are disclosed. The photoconductive film 34 having such a composition has a thickness of 2-6 mu.

3 (b) schematically shows a charging process in which the photoconductive film 34 of the double coated face plate 18 is charged with positive charge in the dark room by the conventional discharge device 36 as described above. The discharge device 36 is applied to the + electrode of the DC power source of +200 to +700 volts, the electrode is applied to the conductive film 32 and grounded at the same time, the discharge device 36 applied to the + electrode in this manner is the face plate By moving across the photoconductive film 34 of 18, the photoconductive film 34 is charged with positive charge.

FIG. 3 (c) shows an exposure process. First, the shadow mask 16 is mounted on the panel 12 and the conductive film 32 is earthed, and then the charged photoconductive film 34 as described above. ) Is also exposed in the dark room by the xenon flash lamp 38 with the lens 40 through the shadow mask 16. Therefore, in this process, when the xenon flash lamp 38 is turned on and the light beam of the lamp 38 is irradiated to the photoconductive film 34 through the lens 40 and the shadow mask 16, the shadow of the shadow mask 16 is reduced. Portions of the photoconductive film 34 corresponding to the aperture or the slits 16a are exposed, and the positive charges of the exposed portions are released through the conductive film 32 by the visible light, which is illustrated in FIG. As described above, only the exposed portion is in a non-charged state. In this way, a latent image of a predetermined arrangement is formed on the photoconductive film. In the case of the xenon flash lamp 38 described above, in order to attach a light absorbing material to the color, the xenon flash lamp 38 preferably has a structure in which the light beam moves between three positions so as to coincide with the incident angle of each electron beam.

FIG. 3 (d) schematically shows a development (adhesion of fluorescent particles or light absorbing material) process. In this step, the developing container 42 contains a dry light absorbing material fine powder or dry phosphor fine powder and a carrier bead capable of generating static electricity by contact with each powder. The carrier beads for the light absorbing material are in contact with the fine powder so that the light absorbing material particles can be charged with -charge and the fluorescent particles can be charged with + electrons. The panel 12 from which the shadow mask 16 is removed is installed on the developing container 42 containing the above-described powder so that the photoconductive film 34 can contact the powder.

At this time, the negatively charged light absorbing material in the mixed powder is attached to the non-exposed portion of the photoconductive film 34 charged with positive charge, and the positively charged fluorescent particles are positively charged photoelectric charge. In the non-exposed part of the coating film 34, it adheres only to the exposed part of the photoconductive film 34 which is in a non-charged state by reversal developing. In this way, a real image of the light absorbing material or the phosphor is formed.

FIG. 3 (e) shows a fixing process by infrared heating, in which dry light absorbing material particles or dry fluorescent particles attached in the above-described developing process are fixed to the photoconductive film 34. Therefore, a suitable polymer component fused by heating is included in the photoconductive film 34 and the dry light absorbing material particles or dry fluorescent particles.

4 shows a process diagram in which the processes described above in FIGS. 3A through 3E are applied to the production of the color cathode ray tube. In FIG. 4, the steps related to the formation of the light absorbing material 21 are omitted, but can be easily understood from the above description. That is, after the panel 12 passes through steps S1 and S2, which are coating processes, the angles of FIGS. 3A to 3E are adhered to the photoconductive film 34 of the light absorbing material between steps S2 and S3. Process, i.e., charging process, exposure process, developing process, and fixing of light absorbing material particles.

In this way, the panel 12 to which the light absorbing material 21 is fixed is fixed to the photoconductive film 34 of the panel 12 by R, G, and B three-color phosphors through the steps S3 to S13. That is, in step S3, the photoconductive film 34 to which the light absorbing material 21 is fixed is first charged with positive charge as in FIG. 3 (b) and the first as in FIG. 3 (c) in step S4. The phosphor portion G is first exposed, and developed in step S5 so that the first fluorescent particles G adhere as in FIG. 3d, and in FIG. As in the first fluorescent particles (G) attached in step S5 is fixed to the photoconductive film 34. In addition, the same processes as those for the first phosphor fixing described above are repeated between the steps S7 to S10 to fix the second phosphor B, and the steps S11 to S14 are also performed for the third phosphor R. In the same manner, the three color phosphors are fixed on the photoconductive film 34. Thereafter, in the lacquer process of step S15, a lacquer film is formed by a conventional method, and an aluminum thin film is also formed by the conventional method in the anodizing process of step S16.

Thus, the panel 12 in which the aluminum thin film was formed is dried by heating at 425 ° C. for about 30 minutes in the air in the baking process of step S17. At this time, volatile components such as the conductive film 32, the photoconductive film 34, and the solvent present in each phosphor and lacquer are removed, and the light absorbing material 21 and each phosphor R, G, and B are shown in FIG. The fluorescent surface 20 formed as follows is obtained. Thereafter, the panel is heat-melted to the funnel and vacuum-treated by attaching an electron gun as in the conventional wet slurry method to complete the cathode ray tube.

In addition, U. S. Patent No. 5,240, 798 (patented on Aug. 31, 1993) discloses a light absorbing material (21) by first fixing three kinds of phosphor particles on the idler coating film 18 by the above-described method and uniformly charging them again. There is disclosed a method for producing a screen of a cathode ray tube which forms a charged open area (a part without phosphor particles) for attaching), and then charges particles of the light absorbing material in opposite polarity to attach to the open area. In this patent, the phosphor particles are first fixed, so that the charging is weak in the portion where the phosphor particles are fixed upon recharging after fixing. Therefore, the light-absorbing material is attached by using the electric force difference between the open portion, which is the weakly charged portion, and the other portions. Accordingly, the exposure process for the light absorbing material 21 is omitted and the opacity of the light absorbing material 21 is improved.

Among the processes described above, FIG. 5 (a) specifically illustrates the relationship between the conventional discharge device 36 and the panel 12 used in the charging process of FIG. 3 (b). In (b), the structure of the conventional discharge device 36 is shown in cross section.

Although the charge amount to the photoconductive film 34 is uniformly exposed and developed in the exposure process of FIG. 3C and the developing process of FIG. Since the panel of curved surface has different radius of curvature, it is impossible to use the straight and thin wire that is most effective for corona discharge. In addition, a plurality of saw-toothed tips for discharging the discharge device 36 are formed at the tip thereof.

That is, in FIG. 5 (a) (b), the discharge device 36 includes a discharge electrode 51 in the center of tungsten stainless steel plate, an insulating plate 53 surrounding the periphery thereof, and a pair for supporting them. And the insulator 54 which is charged between the supporting metal piece 52 and the supporting metal piece 52 and the discharge electrode 51 to insulate the discharge electrode 51 from each other. In addition, the upper end of the discharge electrode 51 is formed of a plurality of sharp teeth (tip) 51a.

An adjustable direct current voltage (V) is applied to the discharge electrode 51 to approximately +1 KV to charge the photoconductive film 34 with + charge. The intensity of the electric field should be about the same so that it can be discharged evenly in all parts and the panel of the cathode ray tube can be uniformly charged.

Thus, the discharge capacity between the discharge electrode 51 and the counter electrode 32 which charges the photoconductive film 34 with + charge is the distance d ₁ between the tip 51a and the counter electrode 32 and between the tips. It depends greatly on the distance d ₂ , the shape and sharpness of the tip, the strength of the electric field, the thickness of the conductive film and the photoconductive film, and the like. The amount of charge that is made cannot be uniform over the entire surface even in the center of the panel. That is, the maximum discharge occurs at the uppermost portion closest to the tip 51a, and weakens toward the circumference.

Accordingly, there is a problem of causing uneven exposure and development in the above-described exposure process and development process and causing the phosphor particles to be uneven even in a desired arrangement structure.

In addition, in FIG. 5 (a), the panel 12 can be divided into a panel face plate 18 and a panel side wall portion 18a, which are curved surfaces, and the peripheral portion b, rather than the central portion a of the panel face plate 18, is formed. In c), corona discharge is strongly generated, which makes it difficult to secure uniformity of charging. Furthermore, even if these conditions are met once, it is easy to be distracted during the operation of the discharge device, so it is not difficult to repeatedly charge the panels evenly over several times. Therefore, it is difficult to apply them for the purpose of mass production. There is a more difficult problem.

The present invention has been made to solve the above problems, and the cathode ray is not only uniformly charged with a photoconductive film in order to obtain a developing density such as a uniform phosphor, but also by a simplified process of removing the complex corona discharge process and the apparatus described above. It is an object of the present invention to provide a method for producing an electrophotographic screen of a cathode ray tube capable of producing a tube.

In order to achieve the object of the present invention, the present invention is a screen manufacturing method of an electrophotographic cathode ray tube for forming a fluorescent surface on the inner surface of the panel; (1) forming a volatile conductive film on the inner surface of the panel; (2) a secondary coating step of forming an insulating film for electrical insulation on the conductive film; (3) a tertiary coating step of forming a volatile first photoconductive film containing a material sensitive to light rays of a first wavelength region on the insulating film; (4) forming a volatile second photoconductive film on the first photoconductive film containing a material that is sensitive to light in a second wavelength region; (5) Applying a -DC electrode to the second photoconductive film and applying a + DC electrode to the conductive film while exposing the second wavelength region of light to the second photoconductive film over the entire surface to provide a uniform electrostatic charge. A charging step of charging the two photoconductive films; (6) an exposure step of exposing through a shadow mask with light rays of a first wavelength band so as to selectively move the electrostatic charge of the second photoconductive film to the first photoconductive film; And (7) a developing step of attaching the charged fine powder to any one of an exposed portion of the first photoconductive film to which the electrostatic charge is selectively shifted and the remaining non-exposed portion in the exposing step (6). Provided is an electrophotographic screen manufacturing method of a cathode ray tube.

In addition, the present invention is a screen manufacturing method of an electrophotographic cathode ray tube for forming a fluorescent surface on the inner surface of the panel; (1) forming a volatile conductive film on the inner surface of the panel; (2) a secondary coating step of forming an insulating film for electrical insulation on the conductive film; (3) a tertiary coating step of forming a volatile first photoconductive film containing a substance sensitive to light rays of a first wavelength region on the insulating film; (4) a fourth coating step of forming a volatile conductive film on the first photoconductive film; (5) while applying -DC electrode to the conductive film and + DC electrode to the conductive film, the first photoconductive film is selectively filled with the conductive film by exposing the first wavelength band of light through a shadow mask. Charging and exposing the electrostatic charges to the first photoconductive film; And (6) a developing step of attaching the charged fine powder to any one of an exposed portion of the first photoconductive film to which the electrostatic charge is selectively moved in the charging and exposing step (5) and the remaining non-exposed portion. It provides a method for producing an electrophotographic screen of a cathode ray tube, characterized in that.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

6 (a)-(f) schematically show each process according to the present invention. The conductive film 62, the insulating film 64, the first photoconductive film 66, and the second photoconductive film 68 are formed on the inner surface of the face plate 18 in FIGS. 6A through 3A. ) Is in turn coated by conventional coating methods. The conductive film 62 is a conventional composition solution, for example, 1% by weight of Catfloc + c or 1% by weight of Catfloc + c or Catfloc + CL manufactured by Calgon as polyelectrolyte and 1 + 50% by weight of 10% PVA solution. The aqueous solution (the remaining water) is applied by a conventional method and dried. The first photoconductive film coating solution containing the material reacting to the light of the first wavelength region is applied and dried by a conventional method to form the first photoconductive film 66 thereon. The second photoconductive film 68 is also formed by coating with a conventional method with a second photoconductive film coating solution containing a substance sensitive to light in the second wavelength region.

6 (b) schematically shows the charging process, which is different from the conventional method described above. In the state where the negative pole of the DC power is applied to the second photoconductive film 68 and the positive pole is applied to the conductive film 62, the light of the second wavelength range is irradiated to the second photoconductive film 68. In this case, a light blocking filter of a first wavelength region may be used between the light source and the second photoconductive film 68. In this manner, -charge is charged to the second photoconductive film 68, which is formed by placing the capacitor between the conductive film 62 and the second photoconductive film 68 with the insulating film 64 and the first photoconductive film 66 interposed therebetween. Since it forms, charging becomes possible, and it becomes possible to be uniformly charged by making uniform the illuminance of whole surface exposure over the surface of the 2nd photoconductive film 68. FIG.

FIG. 6 (c) schematically shows the exposure process, in which light rays of the first wavelength region are incident on the shadow mask 16 at a desired angle of incidence, and the apertures of the shadow mask 16 having the desired arrangement ( The second photoconductive film 68 and the first photoconductive film 66 of the thin film are exposed through a hole or the slit 16a hole in a desired arrangement. As a result, the exposed portion becomes conductive, and the -charge of the exposed portion charged to the second photoconductive film 68 selectively moves to the first photoconductive film 66. The charge in the non-exposed portion remains on the surface of the first photoconductive film 66 side of the second photoconductive film 68 as it is. Thereafter, as in FIG. 6 (d), a 0-volt power source is applied to the conductive film 62 and the second photoconductive film 68 to release the remaining charges, and as shown in FIG. A latent charge image of a predetermined arrangement is obtained.

6f is similar to the conventional developing process of FIG. The polarity of the static electricity charged in the fine powder is determined depending on which of the exposed portion and the non-exposed portion is attached to the fine powder. In other words, the fine powder is charged to + charge when attached to the exposed portion of the charge, and the fine powder is charged to the non-exposed portion where the charge is released. The fine powder thus charged is strongly attached to the surface of the photoconductive film 66 in a desired arrangement by the action of electrical attraction and repulsive force to form a real image.

The fine powders attached as described above are fixed to the second photoconductive film 68 by heating and fusion by infrared rays or the like as conventionally.

The processes according to the present invention are also repeated for the first to third phosphors R, G, and B similarly as in FIG. 4 in the case of the production of the color cathode ray tube. The panel 12 to be inserted into the light absorbing material 21 is formed on the inner surface of the face plate 18 in a desired arrangement by a conventional wet screen manufacturing method, a dry screen manufacturing method, or the screen manufacturing method of the present invention described above. It is stuck. However, the light absorbing material 21 does not need to be formed first, and as shown in the above-mentioned US Patent No. 5,240,798, after fixing the phosphors, the light absorbing material 21 is used in a desired arrangement using the manufacturing method of the present invention. Can be attached and fixed.

Thereafter, the laki is coated in accordance with a conventional method, an aluminum film is formed, and heated at high temperature in the air, thereby conducting the conductive film 62, the insulating film 64, the first photoconductive film 66, and the second photoconductive film 68. And other volatiles are removed and the phosphors are fixed to obtain the desired screen.

In addition, in the case where the conductive film is formed instead of the above-described second photoconductive film 68, the charging and charge transfer steps of FIGS. 6 (b) to (d) may be simultaneously performed. alternative to the charging and exposing process of c). That is, in FIG. 6C, when the second photoconductive film 68 is a conductive film, the second photoconductive film 68 is formed through a shadow mask (not shown) while DC power is applied to the conductive film 62 and the conductive film 68. The light of one wavelength region is applied to the first photoconductive film 66 and the conductive film 68 is charged, and only the exposed portion of the charge is transferred from the conductive film 68 to the first photoconductive film 66 in a predetermined arrangement. ), And then the electric charges of the first wavelength region are cut off and the electric power is set to 0 volts to release the remaining charges of the conductive film 62 and the conductive film 68. A latent image can be obtained.

As described above, according to the present invention, an insulating film, a first photoconductive film sensitive to light rays in the first wavelength region, and a second photoconductive film sensitive to light rays in the second wavelength region are formed on the conductive film, and the power is directly applied to the second photoelectric film. By charging the coating film or forming a conductive film instead of the second photoconductive film to form a latent charge image, it is possible not only to eliminate the need for a discharge device such as a corona discharge device, but also to uniformly charge without controlling complicated discharge conditions. Also simplified, there is an effect that can uniform the thickness, size, shape and the like of the phosphor coating.

Although the present invention has been described through the preferred embodiments, the present invention is not limited thereto, and various changes and modifications will be possible to those skilled in the art from the matters described in the claims.

Claims (6)

A screen manufacturing method of an electrophotographic cathode ray tube for forming a fluorescent surface on an inner surface of a panel; (1) forming a volatile conductive film on the inner surface of the panel; (2) a secondary coating step of forming an insulating film for electrical insulation on the conductive film; (3) a tertiary coating step of forming a volatile first photoconductive film containing a material sensitive to light rays of a first wavelength region on the insulating film; (4) forming a volatile second photoconductive film on the first photoconductive film containing a material that is sensitive to light in a second wavelength region; (5) Applying a -DC electrode to the second photoconductive film and applying a + DC electrode to the conductive film while exposing the second wavelength region of light to the second photoconductive film over the entire surface to provide a uniform electrostatic charge. A charging step of charging the two photoconductive films; (6) an exposure step of exposing through a shadow mask with light rays of a first wavelength band so as to selectively move the electrostatic charge of the second photoconductive film to the first photoconductive film; And (7) a developing step of attaching the charged fine powder to any one of an exposed portion of the first photoconductive film to which the electrostatic charge is selectively shifted and the remaining non-exposed portion in the exposing step (6). An electrophotographic screen manufacturing method of a cathode ray tube. The method of claim 1, wherein the fine powder in the developing step (7) comprises any one of the first, second and third phosphor powders, the desired powder for each of the first, second and third phosphor powders. The screen of the electrophotographic cathode ray tube, characterized in that the charging step (5), the exposure step (6) and the developing step (7) are repeatedly carried out to form an arrangement, and then a fixing step of fixing the respective phosphors. Manufacturing method. 3. The charging step (5) and the developing step (7) according to claim 2, wherein the charging step (5) and the developing step (7) are carried out on the light absorbing material powder to form a matrix pattern which separates the arrangement of the first, second and third phosphors immediately before the fixing step. The fixing step is a step of fixing the light absorbing material having a matrix pattern with each of the phosphors arranged, the screen manufacturing method of an electrophotographic cathode ray tube. A screen manufacturing method of an electrophotographic cathode ray tube for forming a fluorescent surface on an inner surface of a panel; (1) forming a volatile conductive film on the inner surface of the panel; (2) a secondary coating step of forming an insulating film for electrical insulation on the conductive film; (3) a tertiary coating step of forming a volatile first photoconductive film containing a material sensitive to light rays of a first wavelength region on the insulating film; (4) a fourth coating step of forming a volatile conductive film on the first photoconductive film; (5) while applying -DC electrode to the conductive film and + DC electrode to the conductive film, the first photoconductive film is selectively filled with the conductive film by exposing the first wavelength band of light through a shadow mask. Charging and exposing the electrostatic charges to the first photoconductive film; And (6) a developing step of attaching the charged fine powder to any one of an exposed portion of the first photoconductive film to which the electrostatic charge is selectively moved in the charging and exposing step (5) and the remaining non-exposed portion. Electrophotographic screen manufacturing method of a cathode ray tube, characterized in that. 5. The method according to claim 4, wherein the fine powder in the developing step (6) comprises any one of the first, second and third phosphor powders, the desired powder for each of the first, second and third phosphor powders. Wherein the charging and exposing step (5) and the developing step (6) are repeatedly performed to form an arrangement, and then a fixing step of fixing the respective phosphors thereon. 6. The charging and exposing step (5) and the developing step (6) for the light absorbing material powder according to claim 5, in order to form a matrix pattern separating the arrangement of the first, second and third phosphors immediately before the fixing step. The fixing step is a step of fixing the light absorbing material forming the matrix pattern with each of the phosphors arranged, the screen manufacturing method of an electrophotographic cathode ray tube.