JPH0687396B2 - Color picture tube manufacturing method - Google Patents

Description

The present invention relates to a method of manufacturing a color picture tube, and more particularly to a method of forming a ceramic layer on the surface of a shadow mask.

(Prior Art) In a shadow mask type color picture tube, a vacuum envelope is generally composed of a rectangular panel, a funnel-shaped funnel and a neck, and a stripe-shaped phosphor layer emitting light of three colors on the inner surface of the panel. A phosphor screen made of is adhered and formed. An in-line type electron gun that emits three electron beams is arranged on the neck. Further, at a position close to and facing the phosphor screen, a shadow mask is supported and fixed by a mask frame, and the mask frame is locked by a stud pin of the panel through an elastic material,
It is supported in the panel.

Generally, the effective electron beam amount passing through the through hole of the shadow mask is 1/3 or less on its mechanism, and the remaining electron beam is projected into the shadow mask and converted into thermal energy,
The shadow mask is heated to about 80 ° C during operation of a general television. In addition, a special color picture tube used for aircraft cockpit and other indicators sometimes shows 200 ° C.
The temperature of the shadow mask may rise before and after. Shadow masks generally have a coefficient of thermal expansion of 1.2 × 10 ^-5.
The mask frame that supports the shadow mask skirt is made of so-called cold-rolled steel containing iron as the main component and has a thickness of 1 mm. It is also formed from the same cold-rolled steel that has been subjected to a blackening treatment with an L-shaped cross section. Therefore, the heated shadow mask easily undergoes thermal expansion, but the periphery of the shadow mask is in contact with the mask frame with a large heat capacity subjected to the blackening treatment, so radiation or conduction causes the shadow mask periphery to move to the mask frame. The heat moves, and the temperature around the shadow mask becomes lower than that at the center. Therefore, a temperature difference occurs between the central portion and the peripheral portion of the shadow mask, and a so-called doming phenomenon occurs in which the central portion of the shadow mask is heated and expanded. As a result, the distance between the shadow mask and the phosphor screen is changed, the accurate landing of the electron beam is disturbed, and the color purity is deteriorated. The phenomenon of mislanding due to such doming is remarkable especially in the initial stage of operation of the color picture tube. In addition, when a high-intensity image is partially projected on the image surface, and especially when this high-intensity image part is stopped for a certain period of time, a high electron flow density part is generated in the shadow mask, and a local doming phenomenon occurs. Cause

As for the doming phenomenon of such a color picture tube, the same applicant as the present applicant applied Si
Japanese Patent Application No. 60-114217 proposes to suppress the doming phenomenon by forming a C layer. Moreover, a ceramic layer containing a metal oxide of silicon and zirconia is formed on the surface of the shadow mask to perform doming. A proposal to suppress the phenomenon is made in Japanese Patent Application No. 60-155981.

(Problems to be solved by the invention) However, when forming the above-mentioned ceramic layer on the shadow mask surface, a desired suspension is applied by air spray, so that the main surface of the shadow mask is as shown in FIG. Particles of metal oxides, carbides, and nitrides as a component filler (13)
The ratio of Therefore, when vibration is applied to the color picture tube during the manufacturing process of the color picture tube, a part of the color picture tube may peel off and the fine particles may drop off. The fallen particles thus generated cause clogging of the holes attached to the shadow mask to deteriorate the image characteristics on the fluorescent screen, and when attached to the electron gun, they induce sparks between the electrodes to deteriorate the withstand voltage characteristics. Etc. Remarkably deteriorate the quality of the color picture tube. The present invention is
The purpose is to prevent the generation of the fallen particles.

[Structure of Invention]

(Means for Solving Problems) The present invention has been made to solve the above problems, and includes a phosphor screen, a shadow mask arranged in the vicinity of the phosphor screen, and a shadow mask of the shadow mask. In manufacturing a color picture tube including an electron gun that emits an electron beam that selectively emits a phosphor on a screen through a through hole, a metal alkoxide compound and a metal oxide are formed on the shadow mask surface. Coating a suspension containing at least one selected from the group of carbides and nitrides, coating a metal alkoxide compound on this coating film,
This is to prevent the generation of fallen particles.

(Function) The metal alkoxide compound applied to the surface of the shadow mask is hydrolyzed by water in the air, etc., and forms a film by the polycondensation reaction of the alkoxides. It can act as a binder and form a strong layer thereof. Therefore, if a metal alkoxide compound is further applied to the coating surface layer containing a large proportion of the filler particles, it acts as a binder as already described, and therefore it is possible to prevent the generation of particles that fall off in the subsequent step.

(Examples) Hereinafter, the present invention will be described in detail based on Examples.

That is, as shown in FIG. 2, a vacuum envelope is composed of a substantially rectangular panel portion (1), a funnel-shaped funnel portion (2) and a neck portion (3). On the inner surface of the panel portion (1), a phosphor screen (4) composed of striped phosphor layers emitting red, green and blue respectively is adhered and formed, and the neck portion (3) is provided with the panel portion (1). ) Are arranged in a line along the horizontal axis of (1), and so-called in-line type electron guns (6) for emitting three electron beams (5) corresponding to red, green and blue are provided. Further, a large number of slot-shaped apertures are vertically arranged at a position facing the phosphor screen (4) in a vertical direction, and a shadow mask (7) in which a large number of the vertical arrays are horizontally arranged is a mask frame ( It is supported and fixed by 8). Further, the mask frame (8) has a stud pin (1) embedded in the inner wall of the upright edge portion of the panel portion (1) via an elastic member (9).
It is supported in the panel part by being locked by (0).

The three in-line array electron beams (5) are deflected by a deflection device (12) outside the funnel section (2), and scan a rectangular range corresponding to the rectangular panel section (1).
In addition, colors are selected through the openings of the shadow mask (7) and landed on the stripe-shaped phosphor layer to reproduce a color image. In addition, the electron beam may be affected by an external magnetic field such as geomagnetism and may not land accurately on the stripe-shaped phosphor layer, so that the color purity of the reproduced image is prevented from deteriorating inside the funnel portion (2). A magnetic shield (11) made of a ferromagnetic metal plate is locked via a frame (8).

As a material for the shadow mask, for example, a photosensitizer such as milk caseinate alkali and ammonium dichromate is applied to both surfaces of a low-carbon steel sheet having a thickness of 0.1 mm to 0.3 mm, which is mainly composed of iron. Get the membrane. Then, a negative original plate having a predetermined through hole pattern is brought into close contact with this resist film and exposed and developed to expose only the metal surface on which the through hole is to be formed. Next, an etchant composed of ferric chloride is sprayed onto the exposed metal surface to form a through hole having a predetermined opening shape. After a flat plate-shaped shadow mask with through holes is cut out into a predetermined outer frame, its peripheral portion is clamped by a blank holder and a die, and the main surface having the through holes is predetermined by an upper punch and a lower knockout. It is formed into a curved surface, and then the peripheral edge portion is bent and formed along the tube axis direction, for example, as a skirt portion for supporting and fixing the mask main surface. The skirt portion of the shadow mask thus formed is supported and fixed to a strong mask frame having an L-shaped cross section, for example.

Next, on one of the effective surfaces having the through holes of the shadow mask,
For example, when the phosphor screen was disposed close to and facing the phosphor screen, a suspension having the following composition was spray-coated on the main surface of the concave surface on the electron gun side to form a layer of about 5 μm.

Mixture of Si (OC ₂ H ₅ ) ₄ and Zr (OC ₄ H ₉ ) ₄ 100g Mixture of MnO ₂ and CoO 300g C ₂ H ₅ OH 600g Spray is sprayed using an Iwata coating machine industry KK air spray gun. It was applied at a pressure of about 3.0 kg / cm ² for about 10 seconds.
Next, a liquid having the following composition was similarly applied on the spray coating film at a spray pressure of about 3.0 kg / cm ² for about 5 seconds.

Mixture of Si (OC ₂ H ₅ ) ₄ and Zr (OC ₄ H ₉ ) ₄ 100g C ₂ H ₅ OH 900g In this way, the shadow mask with the suspension applied on the surface is heated in an atmosphere of 70 ° C or higher. By doing so, the alkoxide compound of silicon and zirconium can be formed into a film, and the particles of MnO ₂ and CoO that are the filler can be firmly fixed to the mask surface. Moreover, the application of the metal alkoxide compound may be performed after the suspension is once dried. The shadow mask (7) thus completed is subjected to a screen forming step in a state of being combined with the panel portion. First, an azide type photosensitive resist film is formed on the inner surface of the panel portion and exposed through a through hole of the shadow mask (7) using an ultra-high pressure mercury lamp. After developing the resist film, graphite is applied and dried, and then developed using a decomposing agent to form a light absorbing strip at a predetermined position on the inner surface of the panel portion. Next, a slurry in which phosphor particles, for example, phosphor particles for blue color, are added to a photosensitive resist film composed of ADC and PVA system is applied to the inner surface of the panel portion, and similarly exposed and developed to form blue light emitting phosphor strips. Thereafter, similarly, green and red light emitting phosphor strips are sequentially formed to form a screen.

The panel structure completed as described above is joined to the funnel part with the frided glass, and after sealing with exhaust gas, a color picture tube is obtained through a predetermined process.

The results of experiments on the withstand voltage characteristics of the 21-inch color picture tube thus obtained are as follows. The withstand voltage was measured by grounding the focus electrode, applying a voltage to the anode, and measuring the voltage at which unnecessary light emission occurred due to field emission from the focus electrode. As can be seen from Table 1, the withstand voltage characteristics were greatly improved.

In this example, MnO ₂ , CoO as the filler, and silicon and zirconium as the metal alkoxide compound were described, but other fillers such as metal oxides such as iron oxide and chrome oxide, carbides such as silicon carbide and boron carbide, and A nitride such as silicon nitride, boron nitride, or the like can be used. Also, as metal alkoxide, silicon, silicon and titanium,
It can also be applied to the case of using alkoxide compounds such as silicon and aluminum, titanium, zirconium.

〔The invention's effect〕

As described above, according to the present invention, it is possible to prevent particles that fall off during the manufacturing process of a color picture tube, and to obtain a color picture tube that is free from hole clogging and has excellent withstand voltage characteristics.

[Brief description of drawings]

FIG. 1 is a partially enlarged view showing an embodiment of the present invention, FIG. 2 is a schematic sectional view of a shadow mask type color picture tube, and FIG.
The figure is a partially enlarged view of a shadow mask used in a conventional color picture tube. (4) ... Phosphor screen, (6) ... Electron gun (7) ... Shadow mask, (13) ... Metal oxide particles (14) ... Metal alkoxide compound

Claims (2)

[Claims] 1. A phosphor screen, a shadow mask provided in the vicinity of the phosphor screen with a large number of through holes, and an electron beam projected onto the phosphor screen through the shadow mask. In a method of manufacturing a color picture tube comprising an electron gun that emits light, the step of forming a large number of through holes in the shadow mask, the step of forming the shadow mask into a predetermined shape, and the shadow A step of applying a suspension containing a metal alkoxide compound as a film forming agent and at least one selected from the group of metal oxides, carbides and nitrides as a filler on the surface of the mask; A method of manufacturing a color picture tube, comprising: a step of applying a metal alkoxide compound, which is an agent; and a step of heat-treating the shadow mask. 2. The metal alkoxide compound is silicon,
The method for producing a color picture tube according to claim 1, which is an alkoxide compound containing at least one selected from the group consisting of silicon and titanium, silicon and zirconium, silicon and aluminum, titanium and zirconium. .