JPH0731983B2 - Color cathode ray tube and method for manufacturing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a color cathode ray tube and a method for manufacturing the same, and more particularly to a shadow mask including a shadow mask and a mask frame that supports a skirt portion of the shadow mask at a plurality of welding points. The present invention relates to a color CRT having a structure and a manufacturing method thereof.

[Technical background of the invention and its problems]

General shadow mask type color CRT has 3
An electron gun that emits an electron beam of a book, a shadow mask that selectively distributes this electron beam by color, a mask frame that is welded to and supported by a plurality of welding points on the skirt portion of this shadow mask, and an electron beam Red by excitation,
It has a phosphor screen having a phosphor pattern which emits three colors of green and blue, and has a structure for observing an image drawn on the phosphor screen through a panel of an envelope. The shadow mask is provided with a large number of through holes, and the respective color phosphor patterns of the phosphor screen and the through holes are precisely associated with each other.

However, the effective electron beam amount that passes through the through hole is 1/3 or less due to the structure of the color cathode ray tube, and the remaining electron beam strikes the shadow mask and is converted into thermal energy. Heat to above 80 ℃. The thermal expansion coefficient of the shadow mask is about 1.2 × 10 ^-5 / ℃
It is formed from a thin plate of cold rolled steel with a thickness of 0.1 mm to 0.3 mm. On the other hand, the mask frame that supports this shadow mask is made of the same cold-rolled steel having a strong L-shaped cross section and having a thickness of about 1 mm. Therefore, the heated shadow mask thermally expands, but the peripheral part is bonded to the blackened mask frame with a large heat capacity, so that heat is transferred from the shadow mask periphery to the mask frame by radiation or conduction. The temperature of the peripheral portion of the shadow mask is lower than that of the central portion. Therefore, a temperature difference occurs between the central portion and the peripheral portion of the shadow mask, causing a so-called doming phenomenon in which thermal expansion mainly occurs in the central portion, causing a purity drift. That is, the distance between the shadow mask and the phosphor screen changes, the accurate landing of the electron beam is disturbed, and the color purity deteriorates.

Such a phenomenon is remarkable especially in the initial stage of operation of the color cathode ray tube. Also, when a high-intensity image is locally drawn, a local doming phenomenon similarly occurs in the shadow mask.

Many proposals have been made for this doming phenomenon from the viewpoint of promoting heat radiation from the central portion of the shadow mask and preventing heat conduction from the shadow mask to the mask frame. For example, U.S. Pat. No. 2,826,538 proposes to provide a black layer of graphite or carbon coating on the surface of the shadow mask in order to promote heat radiation of the shadow mask. In such a color CRT, the temperature of the shadow mask is lowered because the graphite layer acts as a good radiator.

However, since the effect is not sufficient, a technique for applying lead borate glass having a coefficient of thermal expansion lower than that of iron to the shadow mask surface has been proposed for further improving the characteristics.

This technology was able to improve the purity drift characteristics and vibration resistance of iron-based shadow masks and amber-based shadow masks.However, since the glass component contains lead with a high atomic number, the shadow mask is exposed. It is difficult to reduce the elastic reflection of the projecting electrons. Further, since the formation of this lead borate glass is obtained by melting it by heating at a high temperature and then cooling it, stress remains between the shadow mask and the glass layer, and the thickness of the glass layer varies, resulting in a shadow mask It causes deformation. In addition, a structure in which a so-called vitrified layer containing silica as a main component and containing Al ₂ O ₃ , Fe ₂ O ₃ , ZrO ₂ , and SiC is formed is also considered, but usually, the surface of a shadow mask is used for preventing rust or the like. Therefore, since an oxide film layer is formed, there is a three-layer structure of a layer containing silica as a main component, an oxide film layer, and a shadow mask, and there is unevenness in the film formation state of the oxide film layer. Since then, the layer containing silica as a main component and the oxide film layer are peeled off and dropped from the shadow mask, causing defects such as deterioration of withstand voltage characteristics.

This also applies to the lead borate glass layer. That is, when the glass layer and the silica layer are formed on the shadow mask, the oxide film layer of the shadow mask weakens the adhesive force between the two and causes a problem of peeling.

Further, since the silica layer is an insulator, if it is formed on both surfaces including the through holes of the shadow mask, the silica layer is charged up by the electron beam and repulsion of the electron beam occurs, so that the function as the color cathode ray tube is impaired. There is a problem.

[Object of the Invention]

The present invention has been made in view of the above problems,
Silica as a main component without interposing an oxide film layer, which is easy to peel off, on the entire surface of the shadow mask structure consisting of the shadow mask or the shadow mask and the mask frame,
By forming a ceramic layer containing graphite and zirconia, iron oxide, alumina, by reducing the exfoliation of the ceramic layer, and by including graphite,
An object of the present invention is to provide a color cathode ray tube that does not impair the conductivity of a shadow mask having a through hole and a method for manufacturing the same.

[Outline of Invention]

That is, the present invention is one in which a ceramic layer containing silica as a main component and containing graphite, zirconia, and iron oxide alumina is formed on the entire surface of the press-formed shadow mask excluding the welding points with the mask frame, and press-formed A shadow mask structure formed by welding a shadow mask and a mask frame at a plurality of welding points, and a ceramic layer containing graphite, zirconia, iron oxide, and alumina as a main component on the entire surface, and a method for manufacturing the same Is.

Example of Invention

Next, an embodiment of the color cathode ray tube and the manufacturing method thereof according to the present invention will be described with reference to FIGS.

That is, the color picture tube is an envelope (10) made of glass.
Comprises a substantially rectangular panel (11), a funnel-shaped funnel (12) and a neck (13). The inner surface of the panel (11) is provided with a phosphor screen (14) consisting of a stripe-shaped three-color phosphor pattern which emits red, green and blue respectively, while the neck (13) is provided with a panel (11). An in-line type electron gun (16) which emits three electron beams (30) corresponding to red, green and blue is arranged in a line along the horizontal axis of the. Further, a shadow mask (15) having a main surface in which a large number of through holes are formed is arranged close to and opposite to the phosphor screen (14). Around the shadow mask (15), there is a skirt (18) bent to correspond to the outer shape of the panel (11).
Is formed, and a mask frame (17) composed of a frame having an L-shaped cross section is welded and fixed to the skirt portion (18) at a plurality of welding points (21). The mask frame (17) is locked to the pin (20) embedded in the inner wall of the panel (11) via the spring (19).

In such a color picture tube, the three electron beams (30) emitted from the electron gun (16) are deflected by a deflection device (not shown) arranged outside the funnel (12), and the panel ( 11) The rectangular area corresponding to 11) is scanned, the color is selected through the through hole (15a) of the shadow mask (15), and the color image is correctly projected by the stripe-shaped three-color phosphor pattern. I am supposed to draw.

The shadow mask (15) is made of, for example, a 0.12 mm mild steel plate, and is formed into a predetermined curved surface by press molding after forming through holes by ordinary photo etching.
Silica (SiO ₂ ) as a main component, graphite (C), zirconia (ZrO ₂ ), iron oxide (Fe) is formed on the entire surface including the through holes (15a) of the formed shadow mask (15).
A ceramic layer (22) containing ₂ O ₃ ), alumina (Al ₂ O ₃ ) and others is formed.

This ceramic layer (22) is formed by, for example, SiO ₂ 83
%, C 2%, ZrO ₂ 5%, Fe ₂ O ₃ 3%, and Al ₂ O ₃ 2% powders were put into a container as a mixed solution using a diluent consisting of isopropyl alcohol (IPA) to remove the oxide film. The shadow mask (15) that has not been formed is dipped to form a material film for the ceramic layer on the entire surface. Then, annealing is performed to simultaneously anneal the shadow mask (15) and adhere the ceramic layer (22). However, in this case, it is necessary not to form the ceramic layer (22) in the vicinity of the welding point (21) with the oxidation-resistant mask frame (19) in the next step.

The shadow mask with a ceramic layer thus formed has a ceramic layer (2) for the shadow mask (15).
The adhesive strength of 2) is strong and the ceramic layer (22) does not easily peel off. Also, since the shadow mask (15) and the ceramic layer (2) are bonded at the same time as annealing,
2) There is no distortion between and.

The main purpose of forming the ceramic layer (22) on the entire surface including the through holes (15a) is to prevent the generation of rust due to the elimination of the oxide film layer. In this case, graphite is added to the ceramic layer (22). Since the ceramic layer (22) is included as a low resistance layer, repulsion of electrons does not occur.

The steps up to this point are shown in FIG. 3, in which a shadow mask is press-formed (41), a heating furnace is used for degreasing (42), a ceramic layer material is applied (43), and a shadow mask is annealed and ceramics. A layer forming step (44) and a mask frame / shadow mask welding step (45) are performed.

In the embodiment described above, the ceramic layer was previously formed on the shadow mask and then fixed by welding to the oxidation-resistant mask frame. However, the present invention is not limited to this, and the shadow mask press molding step as shown in FIG. (41), degreasing step with heating furnace (42), welding step of mask frame and shadow mask (45), ceramic layer material applying step (43), shadow mask annealing and ceramic layer forming step (44) . In this case, it is needless to say that the mask frame does not need to be subjected to an oxidation resistance treatment.

Further, it goes without saying that the ceramic layer material may be applied by spraying, electrostatic coating or the like other than the above-mentioned dipping.

〔The invention's effect〕

As described above, according to the present invention, by including graphite in the ceramic layer, a low resistance layer is formed, and by removing the oxide film layer of the shadow mask, peeling of the ceramic layer from the shadow mask is reduced, and the characteristics of the color cathode ray tube due to peeling It has become possible to reduce deterioration.

[Brief description of drawings]

1 to 3 are views showing an embodiment of the present invention,
1 is a vertical sectional view, FIG. 2 is an enlarged sectional view showing a part of the shadow mask of FIG. 1, FIG. 3 is a manufacturing process drawing, and FIG.
The drawing is a manufacturing process diagram of another embodiment of the present invention. 11 …… panel, 14 …… phosphor screen 15 …… shadow mask, 15a …… through hole 16 …… electron gun, 17 …… mask frame 18 …… skirt part, 21 …… welding point 22 …… ceramic layer

Claims (4)

[Claims] 1. A ceramic layer containing silica as a main component and containing graphite, zirconia, iron oxide, and alumina is formed on the entire surface of the shadow mask excluding the welding points between the press-molded shadow mask and the mask frame. Characteristic color cathode ray tube. 2. A ceramic layer containing silica as a main component and containing graphite, zirconia, iron oxide, and alumina on the entire surface of a shadow mask structure formed by welding a press-molded shadow mask and a mask frame at a plurality of welding points. A color cathode ray tube characterized by being formed. 3. A step of heating and degreasing after press-molding a shadow mask, and a mixture of a ceramic layer material containing silica as a main component, graphite, zirconia, iron oxide, and alumina, and a diluent, and a diluent. The method further comprises: a step of applying the entire surface, a heating step of annealing the shadow mask and heating for forming a ceramic layer, and a step of welding and fixing the shadow mask to an oxidation-resistant mask frame. Color cathode ray tube manufacturing method. 4. A step of heating and degreasing the shadow mask after press-molding, a step of welding and fixing the shadow mask and the mask frame to form a shadow mask structure, silica as a main component, and graphite and zirconia. A step of applying a mixed solution of a ceramic layer material containing iron oxide and alumina and a diluent to the entire surface of the shadow mask structure, and a heating step of annealing the shadow mask structure and performing heating for forming a ceramic layer. A method of manufacturing a color cathode ray tube, which comprises: