JPH01109638A - Formation of fluorescent screen for cathode-ray tube - Google Patents

Abstract

PURPOSE:To make exposure process and developing process unnecessary, reduce material and electric power consumption, and form a fluorescent screen with high precision, by transcribing a phosphor coating formed in a pattern using screen process printing onto the glass panel of a cathode-ray tube through a transcribing sheet as a medium. CONSTITUTION:On the surface of a base 2 is prepared a release-layer 3 on which a phosphor coating 4 with the specified pattern is prepared using screen process printing and furthermore on said phosphor coating is prepared a cover- coating 5 composed of binder and others to form a laminated substance. A graphite coating 7 is prepared on the inner face of a glass panel 6 for a reflection-type picture tube and is heated at 80 deg.C within a heating furnace. Thereafter, while the phosphor coating 4 of the laminated substance is touched closely to the surface of the graphite coating 7, the laminated substance is pressed from its back face by a roller of 130 deg.C. The phosphor coating is thereby transcribed on. Then the base 2 for backing is peeled off.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for forming a fluorescent screen of a cathode ray tube (hereinafter referred to as CRT) by a transfer method.

Prior Art Color CRT phosphor screens are typically formed by a slurry method. When applying the slurry method to form a phosphor screen of a black matrix type color CRT, there is a step of spin-coating a photosensitive slurry in which graphite particles or phosphor particles are dispersed, and a step of attaching a shadow mask and performing an exposure process. , the hot water development process and the drying process must be repeated four times.

Problems to be Solved by the Invention For this reason, the work of forming a phosphor screen becomes very complicated, and furthermore, it consumes a large amount of phosphor, a large amount of hot water for development, and a large amount of electric power.

Therefore, it is considered to form the phosphor screen by printing, but since the inner surface of the CRT glass panel is not flat, it is very difficult to directly print a phosphor film in a predetermined pattern on the inner surface of the glass panel.

Means for Solving the Problems According to the present invention, there is a printing step in which a phosphor film of a predetermined pattern is attached by screen printing on a release layer of a flat transfer sheet, and a phosphor film on the release layer is attached to a CRT glass panel. and a transfer step for transferring the image onto the inner surface of the substrate by heating, supplying water, or pressing.

Function: A phosphor film with a predetermined pattern is first accurately screen printed onto a flat transfer sheet, and this is transferred onto the inner surface of the glass panel like a decal.
Complicated exposure processing steps and development processing steps are not required, and the consumption of materials such as phosphor particles can be significantly reduced. In addition, the transfer sheet can not only be cut freely, but also curved relatively freely, so even if the glass panel has side walls or has a gently curved inner surface, it can be adapted accordingly. can. Furthermore, the pattern of the printed phosphor film can be inspected before transfer to determine whether it is good or bad.

Embodiment Next, an embodiment in which the present invention is applied to the formation of a phosphor screen in a reflective picture tube, that is, a CRT in which an image projected on the phosphor screen is viewed from the electron beam incident surface side, will be described with reference to the drawings. explain in detail.

Referring to FIG. 1, a transfer sheet 1 is a commercially available so-called heat transfer sheet, and a release layer 3 with a smooth surface is provided on the surface of a base 20 made of flat paper or film. On the surface of the release layer 3, there is a phosphor film 4 with a predetermined pattern attached by screen printing, and on the surface of the phosphor film 4, a thin cover coat 5 made of a binder or the like as described above is provided. There is.

The phosphor ink used in the screen printing is a paste-like product in which phosphor particles are dispersed in an acrylic resin binder (kneaded and dispersed at high density), and the solvent for the binder is xylene or seltulpur acetate. etc. can be used.

After making a predetermined phosphor film pattern on a 300-mesh silk screen using such ink,
Screen printing is performed on the release layer 3 of the transfer sheet 1 using this screen and a squeegee, and a cover coat 5 is provided on the surface thereof.

The thickness of the phosphor film 4 is, for example, 7 cm/cm.

The laminate is applied to the inner surface of a glass panel for a reflective picture tube to transfer the phosphor film 4 to the inner surface of the panel. As shown in FIG. 2, a graphite film 7 is coated on the inner surface of the glass panel 6 in advance. Form it. After heating such a glass panel with a graphite film to about 80° C. in a heating furnace, the phosphor film 4 of the laminate is brought into close contact with the upper surface of the graphite film 7. Then, the laminate is pressed from the back side with a roller having a surface temperature of about 130°C.

This increases the adhesive strength of the binder of the phosphor film 4, and the phosphor film 4 is thermally transferred onto the surface of the graphite film.

Next, measure base 2 for the backing.

In the above example, the glass panel and the laminate were heated during transfer, but it is possible to give the surface of the phosphor film appropriate adhesiveness after printing (in some cases, such heating may be omitted). In this case, transfer can be performed simply by pressing strongly with a roller from the back side of the laminate.

As shown in FIG. 3, the thickness of the phosphor film should be at least 4 cm/cIm2 (emission intensity is almost saturated at about 6 cm/cIm2).

According to another embodiment of the invention, water is used during the transfer. In this case, a transfer sheet is used in which a dextrin film with a thickness of several μm is attached as a release layer on the surface of a base made of flat paper or film. Then, a phosphor film in a predetermined pattern is screen printed on the surface of the release layer in the same manner as described above.

When the obtained laminate with the phosphor film is immersed in water, the release layer dissolves in water, so the transfer method is to adhere the phosphor film to the inner surface of the glass panel or the surface of the graphite film, and apply the backing. Just take the base.

In either case, the phosphor pattern may be one for monochrome tubes, or a dot array or stripe array for color tubes, and even in the case of color tubes, a phosphor screen can be formed in one transfer. can do.

Effects of the Invention As described above, according to the phosphor screen forming method of the present invention, a phosphor film patterned by screen printing is transferred to a CRT glass panel using a transfer sheet as a medium, so an exposure step and a development step are not required.・Consumption of materials such as phosphors, etc.
Power consumption can be significantly reduced, and a phosphor screen with a predetermined pattern can be formed with high precision.

[Brief explanation of the drawing]

FIG. 3 is a perspective view of a glass panel of a reflective picture tube in FIG. 3, and is a characteristic diagram showing the relationship between phosphor film thickness and emission intensity. １・・・・・・・・・Transfer sheet, ２・・・・・・・・・
・Base, 3...Peeling layer, 4...
...phosphor film, 5...cover coat. Name of agent Patent attorney Toshio Nakao One idiot/---Transfer sheet 2-Base S--One stabbing crime waste No. 1 Figure 5-11 Kanogu-
coat a12!1

Claims (1)

[Claims] A printing step of attaching a phosphor film in a predetermined pattern on the release layer of the flat transfer sheet by screen printing, and transferring the phosphor film on the release layer onto the inner surface of the cathode ray tube glass panel by heating, water supply, or pressing. 1. A method for forming a cathode ray tube phosphor screen, comprising a transfer step.