JPH07118276B2 - Color picture tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a color picture tube.

(Prior Art) Generally, in a color picture tube, a vacuum envelope is composed of a panel, a funnel and a neck, and a phosphor screen consisting of a stripe-shaped phosphor layer is adhered and formed on the inner surface of the panel, and a neck is formed on the neck. A so-called in-line type electron gun that emits three electron beams is arranged. Further, at a position close to the phosphor screen, a peripheral portion of the mask frame is supported by the mask frame, and a shadow mask having a large number of slit-shaped openings is supported via an elastic member.

The three electron beams are deflected by a deflection device outside the funnel and scan a rectangular range corresponding to a rectangular panel to reproduce a color image.
Also, the electron beam is affected by an external magnetic field such as geomagnetism,
A magnetic shield is locked inside the funnel to prevent the color purity of the image from deteriorating again.

In such a color picture tube, the number of pitches of the slit-shaped openings of the shadow mask in the horizontal direction needs to be 1/3 of the pitch of the stripe-shaped phosphor layer. Therefore, the effective electron beam that normally passes through the slit-shaped aperture is
It is 1/3 or less, and the remaining electron beam impinges on the shadow mask and the frame, and sometimes heats the shadow mask and the frame to about 80 ° C. Further, in a special color picture tube used for measurement such as cockpit of an aircraft, the temperature of the shadow mask and the frame sometimes rises to around 200 ° C. Such a shadow mask is generally formed of a thin plate having a thickness of around 0.2 mm, which is mainly composed of iron having a relatively large coefficient of thermal expansion.
The periphery is fixed by a strong mask frame of around mm. The surface of this shadow mask and the frame is 500 ° C in an atmosphere such as H ₂ O-N ₂ or CO ₂ -N _2.
It is heated to ~ 600 ℃, and a blackening film mainly composed of iron oxide is formed. However, the electron beam impinging on the shadow mask and the frame heats and expands the shadow mask and the frame to change the interval (hereinafter referred to as q value) between the phosphor screen and the shadow mask, and this q value change is allowed. When the value exceeds the value, the electron beam does not land accurately on the striped phosphor, so-called mislanding occurs, and the color purity deteriorates. In order to suppress the displacement of the landing position of the electron beam due to such thermal expansion of the shadow mask, 36% Ni-
Fe alloys, so-called amber materials, have been put to practical use. Since the coefficient of thermal expansion of this amber material is about 1/10 that of the conventional cold-rolled steel sheet containing iron as a main component, the thermal expansion of the shadow mask can be significantly suppressed. However, a low thermal expansion metal such as amber alloy is generally more expensive than an iron material, and using the low thermal expansion metal for a heavy frame together with a shadow mask leads to a significant increase in cost. Therefore, it is desirable that only the relatively lightweight shadow mask is made of a low thermal expansion metal, and an inexpensive iron material is used for the heavy frame.

(Problems to be solved by the invention) However, according to the structure in which the low thermal expansion metal is used only for the shadow mask, and the shadow mask is welded and bonded to the inner surface of the frame at a plurality of points, the entire shadow mask structure is in operation during operation. When exposed to a high temperature (for example, 200 ° C), the shadow mask made of a low thermal expansion metal and the frame made of an iron material have different thermal expansions. Therefore, as shown by the dotted line in Fig. 5, the shadow mask (5) Are expanded by the frame (7) in a direction perpendicular to the tube axis. As a result, the peripheral portion (5a) of the shadow mask (5) is locally deformed, and the electron beam passing through the transmissive holes of the deformed shadow mask (5b) causes mislanding. As a result, there is a problem that color shift occurs, normal color reproduction cannot be performed, and the effect of using a low thermal expansion material for the shadow mask (5) cannot be obtained.

The present invention has been made in view of the above points, and an object thereof is to suppress the temperature during operation of a frame in a color picture tube having a shadow mask structure using a low thermal expansion material only for a shadow mask. is there.

[Structure of Invention]

(Means for Solving Problems) The present invention provides a shadow mask structure in which a shadow mask made of a low thermal expansion material is welded to a frame made of an iron material at a plurality of points, and the frame has a porous layer on its surface. , A color picture tube having a shadow mask structure whose thermal emissivity is higher than that at the same temperature as the shadow mask.

(Operation) Even if the shadow mask and the frame are exposed to high temperature during the operation of the color picture tube, the heat dissipation of the frame is great, so that no large thermal deformation occurs.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings. That is, as shown in FIG. 1, a vacuum envelope is composed of a substantially rectangular panel (1), a funnel-shaped funnel (2) and a neck (3). Then, a phosphor screen (4) consisting of striped phosphor layers emitting red, green and blue respectively is adhered and formed on the inner surface of the panel (1), and the neck (3) is horizontally mounted on the panel (1). A so-called in-line type electron gun (6) is arranged which is arranged in a line along the axis and emits three electron beams (14) corresponding to red, green and blue. Further, at a position close to and facing the phosphor screen (4), a peripheral portion thereof is supported by a mask frame made of an iron material and having a thermal expansion coefficient of about 1.2 × 10 ^-5 deg ^-1 , and a large number of slit-shaped openings are formed. Are arranged in the vertical direction, and a large number of shadow masks (5) are arranged in the horizontal direction, and are supported via elastic members (12).

This shadow mask (5) has a coefficient of thermal expansion of 1.2 × 10 ^-6 deg
^-1 36% Ni-Fe alloy, which is smaller than iron material, consists of so-called amber material.

The three in-line electron beams (14) are deflected by a deflecting device (9) outside the funnel (2) to scan a rectangular area corresponding to the rectangular panel (1), and a shadow mask ( Color selection is performed through the openings of 5) and landing is performed on the stripe-shaped phosphor layer to reproduce a color image. Electron beam (14)
May not land accurately on the stripe-shaped phosphor layer due to the influence of an external magnetic field such as the earth's magnetism, etc. In order to prevent the color purity of reproduced images from deteriorating, the funnel (2)
A magnetic shield (8) made of a ferromagnetic metal plate is locked inside via a frame (7).

As shown in FIG. 2, a ceramic layer (10) containing metal oxides of silicon and zirconium is formed on the surface of the mask frame (7). This ceramic layer (10)
Can be formed by the following method. That is, silicon containing zircon (ZrSiO ₄ ) as a filler and an alkoxide compound of zirconia, such as ZrSi (OC
The suspension of ₄ H ₉ ) ₄ was applied by a spray method to form a film thickness of about 15 μm.

Example Zircon 500gr Silicon and zirconia alkoxide compound 100gr Isopropyl alcohol 400gr This suspension is sprayed from a distance of 20cm to 30cm at a pressure of about 3kg / cm.
^When the surface of the mask frame is spray-coated in step ² , a film of about 15 μm as described above can be formed in about 10 seconds. In this way, by heating the shadow mask in which the suspension containing the alkoxide compound of silicon and zirconia is applied to the frame surface in an atmosphere of 70 ° C. or higher, the second
A ceramic layer (10) as shown in the figure was obtained. That is,
The alkoxide compound of silicon and zirconia applied to the surface of the frame (7) is hydrolyzed by moisture in the atmosphere in an atmosphere of 70 ° C. or higher, and as a result, a film is formed by the polycondensation reaction between the alkoxides and silicon. Formation of a metal oxide containing zirconia, that is, conversion to ceramics.
In the above example, the suspension was heated after application, but if the suspension is applied while heating at 70 ° C. or higher in order to shorten the manufacturing time, the subsequent heat treatment step can be omitted. Also,
This alkoxide compound of silicon and zirconia has good absorption characteristics of electromagnetic rays in the infrared region, so when hydrolyzing, not in an atmosphere of 70 ° C or higher, but on the surface of the frame to which the alkoxide compound of silicon and zirconia is applied. For example, it was also confirmed that after applying a suspension containing an alkoxide compound of silicon and zirconia while irradiating with infrared rays, sufficient hydrolysis is performed even at room temperature. It is also possible to irradiate infrared rays after coating.

The mask structure completed as described above is incorporated into a panel, joined by a funnel and frit glass, exhausted and sealed, and a color picture tube is obtained through a predetermined process.

Here, the inventors of the present invention have conducted detailed experimental studies on the temperature rise of the frame (7) when the 21-inch 90 ° deflection type color picture tube is operated by the deflection device to which the present invention is applied. Third
The figure shows the result. The horizontal axis represents the thickness of the ceramic layer (10) containing metal oxides of silicon and zirconium, and the vertical axis represents the temperature rise during operation of the frame (7) when the ceramic layer (10) is not formed, that is, Similar to the surface of the shadow mask, the relative value is shown on the basis of the case where the surface of the frame (7) is coated only with the blackened film mainly containing iron oxide. From this figure, it was revealed that the temperature rise of the frame (7) is suppressed by forming the ceramic layer (10) on the surface of the frame (7). This is because the specific surface area of the ceramic layer (10) formed on the surface of the frame (7) is about 50 times as large as the specific surface area of the frame (7). In other words, the surface area of the ceramic layer (10) is equal to that of the frame (7). ) Is about 50 times the surface area, so the heat dissipation is greatly improved. Therefore, the temperature rise is significantly suppressed as compared with the shadow mask having a blackened film mainly composed of iron and oxide. The specific surface area was measured by the BET method which was calculated from the adsorption amount of nitrogen gas at low pressure.

On the other hand, in FIG. 3, when the thickness of the ceramic layer (10) is about 10 μm or more, the temperature suppressing effect is saturated. This is because when the thickness of the ceramic layer (10) becomes thicker, the ceramic layer (10) closer to the surface of the frame (7), in other words, the lower layer of the ceramic layer (10) does not contribute much to the improvement of heat dissipation, It is considered that only the surface layer region of the ceramic layer (10) greatly contributes to heat dissipation.

Incidentally, since the ceramic as in the embodiment of the present invention generally has a high electric insulation, when such a material is used, the mask (5) and the frame (7) are fixed to each other as shown in FIG. It is desirable not to form the ceramic layer (10) on the surfaces (7a) and (7b) of the mask frame of the portion (11). In the embodiment of the present invention, as shown in FIG.
Although the shadow mask (5) is fixed to the inside of the mask frame (7), the effect of the present invention is not limited to this embodiment. For example, as shown in FIG. 4, the shadow mask (5) is attached to the frame (7). It goes without saying that the same effect can be obtained even if the film is fixed to the outside of the.

〔The invention's effect〕

As described above, even if a low thermal expansion material is used as the shadow mask and inexpensive pure iron is used as the mask frame, the thermal emissivity of the mask frame is improved and the shadow mask in operation due to the difference in thermal expansion between the shadow mask and the mask frame. It is possible to obtain a color picture tube having a good color reproducibility and being industrially mass-producible by preventing local deformation of the above and keeping mislanding of the electron beam sufficiently small for a long time from the initial operation.

[Brief description of drawings]

FIG. 1 is a sectional view of a color picture tube according to the present invention, FIG. 2 is a schematic sectional view showing an embodiment of the present invention, and FIG. 3 is a characteristic diagram showing a temperature rise during operation of a mask frame according to the present invention,
FIG. 4 is a schematic sectional view showing another embodiment of the present invention, and FIG. 5 is a schematic sectional view showing deformation of a conventional shadow mask during operation. (1) …… Panel, (2) …… Funnel (3) …… Neck, (4) …… Screen (5) …… Shadow mask, (6) …… Electron gun (7) …… Mask frame, ( 10) …… Ceramic layer

Claims (3)

[Claims] 1. A vacuum envelope in which a substantially rectangular panel is connected to a funnel-shaped funnel and a neck, a phosphor screen formed on the inner surface of the panel, and a phosphor housed in the neck. A color picture tube provided with an electron gun for emitting a plurality of electron beams for exciting the screen to emit light, and a shadow mask suspended by an elastic member via a rectangular frame-shaped mask frame so as to closely face the phosphor screen. 2. The color picture tube according to claim 1, wherein the mask frame has a porous layer on its surface, and its thermal emissivity is higher than the thermal emissivity of the shadow mask at the same temperature. 2. The color picture tube according to claim 1, wherein the mask frame has a ceramic layer containing a metal oxide of silicon and zirconium on the surface thereof. 3. A color picture tube according to claim 1, wherein the mask frame has a coefficient of thermal expansion larger than that of the shadow mask at the same temperature.