JPS62206747A - Color picture tube - Google Patents

Abstract

PURPOSE:To improve the contrast of the picture and the purity drift property, by furnishing a porous electron absorption layer at the main surface of a shadow mask at the electron gun side, and a specific electron absorption layer at the wall face of a permeable hole at the center side of the shadow mask. CONSTITUTION:At the electron gun 6 side of the main surface 13a of a shadow mask 7 installed closely opposing to a screen 4, a porous electron absorption layer 14a containing at least metallic oxides of silicon and zirconium is formed. On the other hand, at the center side wall surface 13b of a permeable hole, an electron absorption layer 14b consisting of a low conductive crystalline lead borate glass including 75wt% of lead oxide PbO, for example, is furnished. Therefore, the flexible reflection of electron beams at the surface of the shadow mask 7 is reduced, and an expansion with heating of the shadow mask 7 owing to the injection of electron beams is controlled. And the contrast of the picture and the purity drift property are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a shadow mask type color picture tube, and particularly to a shadow mask thereof.

(Prior Art) Generally, in a shadow mask type color picture tube, as shown in FIG. There is. On the inner surface of the panel ■ is a phosphor screen (made of striped phosphor layers that emit red, green, and blue light respectively).
A) is adhered to the neck ■, and the so-called in-line electron guns 0 are arranged in a line along the horizontal axis of the panel ■ and emit three electron beams corresponding to red, green, and blue.
is installed. In addition, in a position close to and facing the phosphor screen (A), a large number of slit-like openings are arranged vertically, and a shadow mask (■) in which many slit-like openings are arranged horizontally is formed into a mask frame (8). It is supported and fixed by. Further, the mask frame (8) is supported within the panel by being locked with a stud pin 0Φ embedded in the inner wall of the upright edge of the panel (2) via an elastic member (9).

The three in-line array electron beams 0 are deflected by a deflection device 02) outside the funnel ■, scan a rectangular area corresponding to the rectangular panel ■, and perform color selection through the apertures of the shadow mask ■. It is designed to land on a striped phosphor layer and reproduce color images. In addition, the electron beam may not land accurately on the striped phosphor layer due to the influence of external magnetic fields such as the earth's magnetism.In order to prevent the color purity of the reproduced image from deteriorating, the electron beam is made of ferromagnetic metal inside the funnel. A magnetic shield (2) made of a plate is secured via a frame (3).

Here, the effective amount of electron beams passing through the through holes of the shadow mask is less than 1/3 of its structure, and the remaining electron beams impinge on the shadow mask and are converted into thermal energy.
When a general television is in operation, the shadow mask is heated to about 80'C.

In addition, in special color picture tubes used for indications in aircraft cockpits, the temperature of the shadow mask sometimes rises to 200'CC on the front floor. Shadow mask ω generally has a thermal expansion coefficient of 1.2X10-5
The mask frame (8) is made of a thin plate with a thickness of 0.1 s to 0.3 m and is made of so-called cold-rolled steel whose main component is large iron. is also made of cold-rolled steel with a thickness of approximately 11rIIrI and which has been subjected to a blackening treatment and has a strong cross-sectional shape. Therefore, the heated shadow mask■
easily causes thermal expansion, but since the periphery is in contact with the mask frame, which has a large heat capacity and has been subjected to blackening treatment, heat moves from the periphery of the shadow mask to the mask frame due to radiation and conduction. The temperature around the shadow mask becomes lower than the center. Therefore, a temperature difference is generated between the central portion and the peripheral portion of the shadow mask ω, and a so-called doming phenomenon occurs in which the central portion is relatively heated and expanded.

As a result, the shadow mask ■ and the phosphor screen (to)
This changes the distance between the two, disrupting the accurate landing of the electron beam, and causing deterioration of color purity. The phenomenon of mislanding due to such doming is particularly noticeable in the early stages of operation of a color picture tube. In addition, when a high-brightness image is partially projected on the image plane, and especially when this high-brightness image part is stopped for a certain period of time, a high electron current density area is generated in the shadow mask, causing a local doming phenomenon. wake up

Regarding the doming phenomenon of color picture tubes,
A number of proposals have been made from the viewpoint of promoting heat radiation from the central portion of the shadow mask.

For example, US Pat. No. 2,826,538/1111 proposes providing a black layer made of graphite on the surface of a shadow mask in order to promote heat radiation from the shadow mask. In such a color picture tube, this graphite layer acts as a good heat radiator, so that the temperature of the shadow mask is lowered. However, the black layer made of graphite also has drawbacks such as a negative number of faces. In other words, the adhesion of the black layer deteriorates due to thermal cycles during the thermal process during the manufacturing process of the color picture tube, and when the color picture tube is subjected to imaging, part of it peels off and minute pieces fall off. There is. The black layer generated in this way clogs the holes that adhere to the shadow mask, deteriorating the image characteristics on the phosphor screen, and if it adheres to the electron gun, it induces sparks between the electrodes, deteriorating the withstand voltage characteristics. The quality of the color picture tube will be significantly degraded.

On the other hand, the same applicant as the present application also proposed in Japanese Patent Application No. 148,843/1983 that this doming phenomenon could be suppressed by sealing and bonding lead-borate glass to the surface of the shadow mask by high-temperature heat treatment. .

However, since the glass layer sealed and bonded to the surface of the shadow mask contains lead, which has a very high atomic number, it is difficult to reduce the elastic reflection of electrons that impinge on the shadow mask. Japanese Patent Publication No. 49-14777 proposes a method of nickel plating the vicinity of the electron transmission hole as a method for preventing such electron scattering, but the manufacturing method is too complicated and is not practical. Electron scattering on the shadow mask surface other than the holes cannot be sufficiently eliminated. Electron scattering causes undesired areas on the screen to emit light, resulting in problems of deteriorating image contrast and reducing color purity.

(Problems to be Solved by the Invention) When a black layer, lead-borate glass, etc. are formed on the surface of a shadow mask, there are problems such as peeling of the black layer, difficulty in reducing elastic reflection of electrons, and Problems such as image deterioration due to scattering still remain.

The present invention provides a color picture tube with improved image contrast and purity drift characteristics by reducing elastic reflection of electron beams on the surface of a shadow mask and suppressing expansion caused by heat generation of the shadow mask due to electron beam impingement. The purpose is to

(Structure of the Invention) (Means for Solving the Problems) The present invention provides a shadow mask having a large number of through holes provided close to a phosphor screen, and a shadow mask provided on the side opposite to the phosphor screen of the shadow mask. The main surface of the shadow mask on the electron gun side is provided with a porous electron absorption layer containing metal oxides of silicon and zirconium, and the wall surface of the through hole on the center side of the shadow mask is provided with crystals. By providing an electron absorption layer made of lead borate glass, this color picture tube effectively suppresses the reduction in contrast due to elastic reflection of the electron beam and the displacement of the electron beam due to doming.

(Function) When an electron beam hits the electron absorption layer formed on the main surface of the shadow mask on the electron gun side and the wall surface of the through hole on the center side of the shadow mask (hereinafter referred to as the center side wall surface), this electron absorption layer absorbs electrons. The electron beam is negatively charged with an intensity corresponding to the flow density, and when passing through the hole, the electron beam is repelled by this negatively charged part and its trajectory is corrected so that it moves away from this part, that is, away from the center of the mask. The landing point of the electron beam, which tends to deviate from a predetermined landing point on the phosphor screen in the tube axis direction due to the doming phenomenon that occurs in response to the electron flow density, is returned to the original accurate landing point.

(Embodiments of the Invention) The present invention will be described in detail based on Examples below.The component structure itself of the color picture tube applied to the present invention is the same as that shown in FIG. is omitted.

In a color picture tube as shown in Fig. 1, a porous electron absorption layer containing at least metal oxides of silicon and zirconium is formed on the electron gun side main surface of the shadow mask (2), which is disposed in close opposition to the screen (2). form. In addition, about 75% of lead oxide (PbO) is applied to the center side wall surface of the through hole.
An electron absorbing layer is provided consisting of a low conductivity crystalline lead borate glass containing % by weight. These electron absorption layers are formed before the panel ω and the funnel ■ are sealed together, and the layer on the main surface on the electron gun side is made of silicon and zirconia containing zircon (ZrSiO4>) as a filler as shown in the example below. Alkoxide compounds, such as ZrS 1 (OC4H9)
Apply the suspension of step 4 to the main surface of the shadow mask on the electron gun side.

Example: Zircon,...500gThe electron absorption layer on the side wall of the center of the hole is made of crystalline salt lead borate glass dissolved in a butyl acetate alcohol solution containing a few percent of nitrocellulose. Apply it to the wall and install this shadow mask ■ inside the panel (G).

After this, the panel ■ and the funnel ■ are placed on the specified frame, and the maximum temperature is about 440'C and the holding time is 35
When the shadow mask is passed through a furnace for more than 10 minutes, a porous electron absorption layer containing a gold EM compound of silicon and zirconium is formed on the main surface of the shadow mask on the electron gun side, and a crystallized An electron-absorbing layer of lead-borate glass is formed.

The results of experiments conducted by the present inventors regarding the purity drift characteristics of the 21-inch color picture tube thus obtained are as follows. Figure 2 (A) shows the playback screen pattern.
The completely white pattern shown in Figure 2 (B) and the partially white pattern shown in Figure 2 (B) were used. In (B), a strip (51) having a width of 75 m in the horizontal direction is reproduced on the screen so that it is positioned at two places on the left and right, each 140 m1lt from the center.

The remaining part is black, that is, a non-luminescent part. X marks indicate measurement points. Table 1 shows the measurement results of the amount of beam movement. Measurement conditions: E b = 26.5 kV, IkG; t pattern (A)
1-1500μA, pattern (B) r1100μA
,! :L, ta.

In Table 1 and the same table, the comparative amount refers to a 21-inch color picture tube in which lead-borate glass was sealed and bonded to the electron gun side surface of the shadow mask by high-temperature heating, which was proposed in Japanese Patent Application No. 58-148843. . Therefore, it was confirmed that the purity drift characteristic of the color picture tube according to the present invention is better than that of the conventional color picture tube.

Here, the changes in the trajectory of the electron beam due to doming of the shadow mask will be explained using FIGS. 3 and 4. (In the figures, the same reference numerals indicate the same parts, and FIG. ), FIGS. 3 and 4, the electron beam 0 lands at a predetermined position Q on the screen (A) when the shadow mask ω does not cause the doming phenomenon.

Here, if the density of the electron beam incident on the shadow mask increases and the shadow mask is heated and a doming phenomenon occurs, that is, the electron beam elD with the shadow mask (7a) in a heated state is Moving in the 0 direction, the landing point of the electron beam where the electron beam should land is also from @ (22a)
Move to. In other words, the electron beam, which should originally land at point 0, lands at a point on the tube axis side (22) due to the doming phenomenon.
If there is a mislanding at point a) and the amount of mislanding at points 0 and (22a) exceeds the limit of the landing margin due to the arrangement of the light emitting phosphor groups of each color, color purity will deteriorate.

In the case of the present invention, the main surface of the shadow mask on the electron gun side (
13a) and the center side wall surface (13b) of the through hole have an electron absorption amount (1/Ia) (14b), so that they are negatively charged in accordance with the electron flow density. This means that this electron absorption layer has a thickness equal to or greater than the average depth of penetration of electrons, approximately 10/jj71 in this example, and has a thickness of 1 or less for primary electron energy, usually 10 KeV to 30 KcV. This means that it has a secondary electron emission coefficient. And this negative charge is transferred to the electron beam (
20 to deflect the trajectory (5a) in a direction away from the tube axis (b). Therefore, due to the doming phenomenon, the landing point (22a) of the electron beam, which was supposed to move from the predetermined landing point @ in the direction of the tube axis (B), acts in a countervailing manner to return to the original landing point 0, and the doming Even if this phenomenon occurs, mislanding of the electron beam can be suppressed and reduced. Such a mislanding suppressing effect is achieved by the electron absorption layers (14a) and (?4b).
) are formed on the electron gun side main surface (13a) of the shadow mask and the center side wall surface (13b) of the through hole, so that the electron absorption layer (14a),
A negative charge distribution as shown in (14b) is generated, and at the electron flow density during normal image projection, this landing suppression effect is weak and sufficiently within the landing margin, but if it causes a doming phenomenon, acts more effectively in cooperation with the doming suppressing effect. In addition, as long as the tube is in operation, the electron beam and secondary electrons from the screen surface, etc. are constantly bombarding the electron absorption layer, so the area of action is very large, and there is a time lag in which the suppression effect occurs. There are almost no

Assuming that an electron absorption layer is also formed on the wall surface (13C) and is similarly negatively charged, the electron beam passing through the center of the through hole 0Φ of the shadow mask (2D is a layer formed within the area of the through hole Oe)
14b) will cancel out the orbit correction effect of the electron beam due to the negative charge, or encourage mislanding. Furthermore, if there is an electron absorption layer on the wall opposite to the tube axis, the beam will be kicked by the electron absorption layer due to the relationship with the incident angle of the electron beam, and the beam projected on the screen will have a size and shape that are different from the initial target size and shape. It is most preferable that different stratification does not exist, but it is very difficult to eliminate it at all in manufacturing, and if the number of layers is less than about 115, it may be difficult to avoid the deflection effect due to negative charging or the problem of It was confirmed that there was no impact. Fifth
In the figure, the horizontal axis shows the thickness of the electron absorption layer formed on the wall surface on the side opposite to the tube axis, with respect to the thickness of the electron absorption layer formed on the wall surface on the center side of the through hole of the shadow mask. The axis shows the amount of movement of the electron beam due to doming in relative values.

In addition to the deflection effect due to the charging of the electron absorption layer described above, the improvement of the utility drift characteristic by the present invention is achieved by the porous electron absorption layer containing fully bent oxides of silicon and zirconium provided on the main surface on the electron gun side. The thermal emissivity of the shadow mask is approximately 0.9, which is much higher than that of conventional shadow masks.
Another major factor is to promote heat dissipation from the shadow mask and suppress the temperature rise of the shadow mask.

Therefore, in this example, zircon (CO
203), these fillers act as black pigments. In general, the thermal emissivity of the ceramic layer can be improved, and on the other hand, other experiments by the present inventors have confirmed that even with nitrides and carbides as fillers, similar effects can be obtained.

Next, the contrast characteristics of the color picture tube according to the present invention and the color picture tube according to Japanese Patent Application No. 58-148843 mentioned above were compared. That is, as shown in FIG. 6, an image pattern was reproduced on the screen. This screen (
30) has a white part (31) of 300 s x 100 m arranged above the center of the screen, and the remaining part (32) is black. The X marks are measurement points, each 30 points downward from the center of the screen.
! M1. I placed f3os. Each point is rfl, rf2
The dark area luminance results are shown in Table 2. The measurement conditions are: color picture tube anode voltage Eb = 26.5kV, total 77 solenoid m current IK = 500μA, white color is 9300'
It was set as K+27MPCD.

Table 2 It is clear from Table 2 that the brightness of dark areas can be reduced in this example. This means that the elastic scattering of electrons is reduced, mainly because the atomic numbers of 3i and zr, which are the constituent components of the electron absorption layer (14a) on the electron gun side, are 14.40 and a comparative amount of lead. This is because it also depends on the fact that the Pb and Ba of the borate glass layer are lower than 82 and 56.

Next, after continuously operating the color picture tube of this example for 3000 hours, the residual emission rate was measured.
It was found that the improvement was 80% compared to the initial operation. Conventionally, 70% has been considered the standard, so this represents an improvement of more than -00%. This is presumed to be because the porous electron absorption layer containing gold IImide of silicon and zirconium provided especially on the electron gun side of this example adsorbed gas, and especially the silicon oxide (S) used as a binder.
It is thought that in2) acted effectively.

It is also thought that gas generation was suppressed because a dense electron absorption layer was formed on the surface of the shadow mask.

Therefore, it is effective to form an electron absorption layer as described above, particularly on the electron gun side surface of the shadow mask, where the electron beam directly impinges on the shadow mask and the surface becomes extremely hot and tends to generate unstable gas. Of course, the working time will increase slightly, but as shown in Figure 4, if the entire shadow mask surface is covered with the ceramic layer of the present invention, the generation of unstable gas from the shadow mask will be almost suppressed. Needless to say.

(Effects of the Invention) As described above, according to the present invention, an electron absorption layer mainly composed of metal oxides of silicon and zirconia is formed on the electron gun side surface of the shadow mask, and the center side wall surface of the through hole is By forming an electron absorption layer made of crystalline lead-borate glass, the contrast characteristics and purity drift characteristics are improved, and a color picture tube with good emission life characteristics and suitable for industrial mass production is obtained. I can do it.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing the configuration of a shadow mask type color picture tube, and FIGS. 2(A) and 2(B) are reproduction image patterns illustrating the utility drift characteristics of the embodiment of the present invention. A schematic diagram, FIG. 3 is a schematic diagram for explaining the movement of an electron beam due to doming of a shadow mask, and FIG.
One embodiment of the present invention is shown, and FIG. 5 is a schematic diagram showing an enlarged view of part A in FIG. 3, and FIG. FIG. 6 is a characteristic diagram showing changes in the amount of movement of the electron beam due to doming of the shadow mask when the height is changed. FIG. 6 is a schematic diagram of a reproduced image pattern illustrating the contrast characteristics of the embodiment of the present invention. )...phosphor screen, ■...electron beam, ■
...Electron gun, ■...Shadow mask, (14a)
, (14b), -・electron absorption layer. Agent Patent Attorney Noriyuki Chika Yudo Norio Ogo Figure 1

Claims (3)

[Claims] (1) A phosphor screen, a shadow mask with a large number of through holes installed close to the phosphor screen, and an electron beam that selectively causes the phosphors on the screen to emit light through the shadow mask. In the color picture tube, an electron absorption layer containing a metal oxide of silicon and zirconium is provided on the electron gun side surface of the shadow mask, and at least the center of the shadow mask of the through hole is provided. Lead oxide (PbO) is placed on the side wall.
) A color picture tube characterized in that it is provided with an electron absorption layer made of crystalline lead-borate glass containing 70% to 85% by weight of. (2) The maximum thickness of the electron absorption layer formed on the wall surface facing the center side wall surface of the through hole of the shadow mask is
2. The color picture tube according to claim 1, wherein the color picture tube has a thickness that is approximately 1/5 or less of the thickness of the electron absorption layer formed on the wall surface on the center side of the through hole. (3) The electron absorption layer on the electron gun side of the shadow mask is
3. The color picture tube according to claim 1 or 2, characterized in that the color picture tube contains at least one of oxide, nitride, and carbide.