JPS63279539A - Manufacture of cathode-ray tube - Google Patents

Abstract

PURPOSE:To improve luminance in a high current density area and yellowing in a fluorescent screen by rotatingly appling a phosphor slurry 12 having phosphor/slurry weight ratio of 14.0-30.0 on the inner surface of a panel, and forming thereon a lacquer film and a metallized film, thereby a fluorescent screen is formed. CONSTITUTION:A phosphor slurry 12 having phosphor/binder ratio in weight of 14.0-30.0 is rotatingly applied on the inner surface of a panel 1 and is exposed and developed thereafter to form a phosphor layer, while a lacquer film is formed on the phosphor layer and a metallized layer is formed on the lacquer film. Consequently, the phosphor charge ratio in the phosphor layer increses in a fluorescent screen to improve the density of the phosphor layer, while the mirror condition in the metallized layer is improved, resulting in that phosphor emission energy can be taken out effectively in the front face of the panel and heat generated at the fluorescent screen can be discharged efficiently to the panel face. It is thus possible to improve luminance and yellowing characteristics in a cathode-ray tube used in a so-called high current density area in a projector or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a cathode ray tube, and particularly to a method for forming a fluorescent surface that provides high brightness.

[Summary of the invention]

In the formation of the fluorescent surface of cathode ray tubes used in high current density regions, the present invention utilizes spin-coating of a phosphor slurry with a phosphor/binder (weight ratio) of 14.0 to 30.0 on the inner surface of the panel. After that, a phosphor layer is formed by exposure and development, and then a metal back layer is formed on the phosphor layer to produce a fluorescent material with high brightness and improved brightness deterioration due to burnout (burning is a characteristic). It is designed to provide a light surface.

[Conventional technology]

2. Description of the Related Art Projection type televisions, so-called projectors, that enlarge and project high-brightness color television images to create a large screen have been put into practical use. The cathode ray tube of such a projector is required to be used in a high current density region and to have high brightness. The conventional method for forming the phosphor surface of a cathode ray tube for a projector is to form a phosphor layer on the inner surface of the panel by a precipitation method, and then apply A to the phosphor layer via a lacquer film (intermediate film).
A method of forming a metal back layer using N, or using a flat panel, forming a phosphor layer on the inner surface of this flat panel by screen printing, and then forming an intermediate film using the same printing method.
A method of forming a metal back layer using /It' is known.

[Problem that the invention seeks to solve]

By the way, in the case of the above-mentioned precipitation method, the phosphor particles are precipitated and deposited in an aggregated state, so the phosphor layer itself is not dense, and the filling rate of the phosphor in the phosphor layer is Approximately 30
Volume % is low. In addition, the surface of the phosphor layer is highly uneven;
Even when the metal back layer was formed through a lacquer film, the mirror surface condition of the metal back layer was not so good.

In addition, in the case of the printing method, although the filling rate of the phosphor in the phosphor layer is higher than that of the precipitation method, there is a limit, and in the case of the metal back layer, part of the intermediate film is covered with the phosphor. Because it penetrates, it is formed along the surface of the phosphor layer, and as a result, the specular state of the metal back layer is poor.

The filling rate of the phosphor and the specular state of the metal back layer greatly affect the brightness, and also affect the so-called heat dissipation effect that releases heat to the panel side when the temperature of the phosphor layer increases during operation.

Therefore, in conventional three-tube projectors, for example, it is difficult to efficiently extract the luminous energy of the phosphor coated on the phosphor surface to the front of the phosphor surface, making it difficult to obtain high brightness. In addition, if a cathode ray tube is used in a region with a higher surface current density for a long time to compensate for the inefficiency of using the luminous energy of the phosphor, the phosphor changes in quality due to temperature rise and the luminous efficiency decreases. The so-called "burning phenomenon" occurred, and brightness deterioration was accelerated. The effect of burnout was particularly large on blue phosphors.

On the other hand, in general color cathode ray tubes, which have a color phosphor surface made of red, green, and blue phosphor layers painted at fine pitches, a slurry method is used to form the color phosphor surface. There is. This slurry method involves a so-called aging process in which phosphor slurry is injected into the panel and the phosphor settles while rotating the panel, and then a shaking-off process in which excess phosphor slurry is discharged from inside the panel. ,
After going through a drying process to dry the phosphor coating formed on the inner surface of the panel, it is exposed to light in a predetermined pattern using a color sorting mechanism as a mask, and developed to form a color phosphor layer. It is done every time.

In this case, the phosphor slurry used has a limit to the width of the phosphor stripes (or dots), so there is a limit to the amount of exposure (i.e., if the amount of exposure is too large, the adjacent color phosphor layer will be affected). Therefore, the phosphor (P
) and binder (B), that is, the P/13 ratio, is 6 to 1.
It is set at around 2. In addition, the specific gravity of the slurry is 1.25 to 1.
．． 37. The aging time is about 15 to 25 seconds, so that the coating weight of the phosphor in the phosphor layer is 2.0 to 3.
It is 0mg/crA. Therefore, when using the slurry method used to form the phosphor surface of conventional color cathode ray tubes, the filling rate of the phosphor in the phosphor layer is limited to about 40% by volume.

In view of the above-mentioned points, the present invention provides a method for manufacturing a cathode ray tube that can obtain high brightness and form a fluorescent surface with improved firing characteristics in a cathode ray tube used in a high current density region. This is what we provide.

(Means for Solving the Problems) The present invention provides a phosphor/binder (ffll ratio), that is, P/
After spin-coating a phosphor slurry with a B ratio of 14.0 to 30.0 on the inner surface of the panel, it is exposed and developed to form a phosphor layer, and a lacquer film as an intermediate film is formed on this phosphor layer. form,
A metal back layer is formed on this lacquer film to form a fluorescent surface.

In this case, the phosphor coating weight of the phosphor layer is 4.0~
About 8.0 mg/cd is preferable. The coating weight of the phosphor is influenced by the specific gravity of the phosphor slurry and the aging time, so the specific gravity of the phosphor slurry is 1.4.
0 to 1.50, and the aging time may be about 40 to 60 seconds. Further, the coating thickness of the phosphor layer is preferably 20 to 40 μm. If P/B is less than 14, it is not possible to improve the brightness of a projector, for example, compared to the conventional one, and if P/B is greater than 30, the adhesive strength of the phosphor layer to the panel is reduced. If the coating weight of the phosphor in the phosphor layer is less than 4.0 mg/ctl, the electron beam will not effectively hit the phosphor and the electrical energy contributing to light emission will decrease. If the amount exceeds 8.0 mg/-, the phosphor on the surface side of the phosphor layer will be excited by the electron beam and emit light, but there will be some phosphor on the panel side that is not hit by the electron beam, causing the excitation to emit light. light is scattered and absorbed,
The light energy extracted to the front of the panel is reduced.

In forming the lacquer film, the surface of the phosphor layer can be wetted with a dilute PVA solution or colloidal silica solution as a pretreatment.

The present invention is applied to a high-brightness cathode ray tube for projection such as a projector and a high-brightness cathode ray tube for direct viewing.

[Effect]

According to this method, the phosphor layer becomes dense and the phosphor filling rate in the phosphor layer becomes 50% by volume or more. Furthermore, since the difference in unevenness on the surface of this dense phosphor layer is small, and a lacquer film is used as the intermediate film, the specular state of the metal back layer is extremely good, and the reflectance of the metal back layer is increased. Therefore, higher brightness can be obtained compared to conventional ones. In addition, since the phosphor is dense, the thermal conductivity of the phosphor layer is good, and the reflectance of the metal back layer is good, so infrared rays can be reflected toward the panel side. The generated heat can be quickly transferred to the panel surface. As a result, the temperature rise of the phosphor particles during light emission can be suppressed, and deterioration in brightness of the phosphor is reduced. That is, the properties of the sintered material are improved. Incidentally, when applied to a cathode ray tube for a projector, the brightness of the blue fluorescent surface is 55% lower than that of the conventional method.
0% improvement, and the burning phenomenon was reduced to 1/2. Especially Z
nS: AgAI2 (Ag, Ml concentration 3~
When using a blue phosphor with a phosphor increased by 10 times, the brightness was improved by 60% when combined with this method.

For example, in the case of a cathode ray tube for a projector, unlike the case of conventional color fluorescent surfaces, it is a monochromatic fluorescent surface, so even if the binder is small, it is difficult to apply the phosphor slurry and then expose it. The amount of exposure can be sufficiently increased, and the adhesive hardness of the phosphor layer to the panel after exposure can be maintained sufficiently.

In addition, as the phosphor filling rate increases, the contact area between the phosphors and the phosphor and the metal back layer increases after baking, and the adhesion of the metal back layer also increases. Eliminates floating of the back layer.

(Example) A case will be explained in which the application is applied to the formation of a fluorescent surface of a cathode ray tube for a three-tube projector. A flat panel is used as the panel of the cathode ray tube. An effective screen is defined in advance on the inner surface of this flat panel. Then, a frame-shaped carbon layer is formed to apply a predetermined potential to the fluorescent surface.The flat panel (1) on which the carbon layer has been formed is placed on a suction pad (2) as shown in FIGS. ).This suction pad (2)
is a concave mounting portion (3) into which the flat panel (1) is fitted in a planar manner so as to receive the peripheral side and front peripheral end portions of the flat panel (1).
and a peripheral side wall (4) extending upward from the upper surface of the concave mounting portion (3) so as to surround the entire circumference of the fitted panel (1).
). A flow stopper (5) is integrally provided on the lower surface of the concave mounting portion (3) and abuts against the front peripheral end portion of the panel (1) over the entire circumference of the panel (1). In this case, with the panel (11) fitted onto the mounting portion (3), the concave mounting portion (3) should be The depth, more specifically, the depth d between the upper surface of the mounting part (3a) and the stopper part (5), is selected to be the same as the thickness of the flat panel (1). When suctioning air through the hole (6), it prevents air leakage and adsorbs and holds the panel on the pad, and when the phosphor slurry described later is injected and spin coated, the fluorescein This is to prevent the body slurry from flowing to the front side of the panel through the gap between the concave mounting part (3) and the panel (1). A notch (10) is provided corresponding to one opposing side of the panel (11) to facilitate attachment and detachment of the panel (11). (6) is a center hole provided at the bottom of the suction panel. This suction pad (2) is constructed by integrally molding, for example, from various rubber materials. If, for example, a retainer Fi (8) of AI2!rI!! with a center hole is placed at the bottom, the support plate (7), which is integrally attached to the rotation shaft (not shown) of the slurry coating machine, will be attached to the suction pad ( 2) Placed on the back side of
With the suction pad (2) being held between the support plate (7) and the holding plate (8), tighten the holding plate (8), the suction pad (2), and the support plate (7) with the screws (9). ).

Next, as shown in FIG. 3A, after cleaning the panel (1), the panel (1) is rotated at a rotational speed of, for example, IQ rpm, and then preheated to 50° C. with a heater (11). Next, as shown in FIG. 3B, the fluorescent slurry (12) is injected into the suction pad (2) on which the panel (L) is attached, and the panel (1) is rotated at a rotation speed of, for example, 10 rpm. While 40-6
In the case of a blue cathode ray tube which is aged for 0 seconds, a blue phosphor slurry having the following composition is used as the fluorescing slurry.

Slurry composition Blue phosphor (ZnS: AgA12) 50
00g polyvinyl alcohol 250g ammonium dichromate 10g water
6500 ml colloidal silica 20a+ 1 surfactant 2 g The P/B of this phosphor slurry is 20.

Next, after the panel is revolved, excess slurry (12) is shaken off as shown in FIG. 3C. In this case panel (1
) is, for example, 120 rpm, and the swing-off time is about 15 seconds. Next, as shown in the third diagram, panel (1)
The phosphor slurry coating film (14) is dried while being rotated at a rotational speed of, for example, 10 rpm via a heater (13).

Next, a region partially on the carbon layer, including portions corresponding to both effective surfaces of the phosphor slurry coating (14), is exposed and developed with water to form a blue phosphor layer.

Next, while the phosphor layer remains wet with water, a dilute PVA solution is spin-coated on the surface of the phosphor, and then a lacquer having the composition shown below is spin-coated to form a lacquer film that will serve as an intermediate film. .

Lacquer composition: Acrylic resin: 4 wt% Solvent (toluene): 96 wt% Next, after drying with warm air or air drying, M is vapor-deposited to form a metal back layer, and baked to form the desired blue fluorescent surface.

In the case of a green cathode ray tube, Y3A is used as the phosphor.
126 012: Tb+ Y3AI2X Ga(
s-x)01z: Tb or Zn2SiO4: M
A green fluorescent surface is formed using any one type of phosphor n or a mixture of a plurality of phosphors, and otherwise in the same manner as above.

In addition, in the case of red cathode ray tubes, Y2O3 is used as the phosphor.
:f! A red fluorescent surface is formed using u and otherwise in the same manner as above.

According to the cathode ray tube for a projector of this example, it was confirmed that the brightness was improved by 60% compared to the conventional one. In addition, the properties of the yaki were also improved.

In addition to the cathode ray tube for a three-tube projector, the present invention also applies to a cathode ray tube for a single-tube projector having a phosphor surface made of a mixed phosphor of multiple colors (for example, yellow and blue), or a cathode ray tube for a single-tube projector, for example. It can also be applied to the formation of fluorescent surfaces in high-brightness direct-view cathode ray tubes, etc., which have color-coded fluorescent surfaces.

Further, the present invention is applicable not only to flat panels but also to ordinary panels with skirt portions, for example.

〔Effect of the invention〕

According to the present invention, the filling rate of the phosphor in the phosphor layer on the phosphor surface is improved to make the phosphor layer denser, and the mirror state of the metal back layer is improved. The energy emitted by the phosphor can be effectively extracted to the front of the panel, and the heat generated on the phosphor surface can be efficiently radiated to the panel surface. As a result, it is possible to achieve higher brightness and improved thermal characteristics of cathode ray tubes used in so-called high current density regions such as projectors.

[Brief explanation of the drawing]

1 and 2 are a plan view showing an example of a suction pad used when spin-coating a phosphor slurry on a flat panel in the present invention, and a cross-sectional view taken along the line A-A of the same, and FIG. 3A
-D is a process diagram showing a process of applying a phosphor slurry according to the present invention. (1) is a flat panel, (2) is a suction pad, (11)
. (13) is a heater, (12) is a phosphor slurry, (14)
) is a phosphor slurry coating.

Claims (1)

[Claims] After spin-coating a phosphor slurry with a phosphor/binder (weight ratio) of 14.0 to 30.0 on the inner surface of the panel, exposure,
A method for manufacturing a cathode ray tube, comprising the steps of: developing to form a phosphor layer; forming a lacquer film on the phosphor layer; and forming a metal back layer on the lacquer film. .