JPS62188135A - Color picture tube - Google Patents

Abstract

PURPOSE:To hold down mislanding all over the effective faceplate, by forming an electron absorbing layer on the main surface of the electron gun side of the shadow mask of a color picture tube. CONSTITUTION:An electron absorbing layer 31 is formed on the center side wall surface 17a of a transmitting hole 27 of a shadow mask 17, and a part of the layer is located on the main surface 17b of the side of the shadow mask where electron beams collide. Thereby, when electron beams are deflection- scanned, the layer is negatively charged corresponding to the density of the electron beams. The negative electric charge on the center side wall surface of the transmitting hole 27 deflects an electron beam 15C as shown by the solid line 15a. Therefore, the landing spot 42a of an electron beam which is apt to move in a pipe axis 47 direction more than a prescribed landing spot 42 owing to a doming phenomenon is counterbalancely operated to return to the landing spot 42 again. Thus, even if the doming phenomenon is brought about, the mislanding of electron beams can be held down and reduced.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a color picture tube of the dow mask type,
Especially regarding that shadow.

(Prior Art) In general, a color picture tube with a shadow mask consists of a fluorescent screen with light-emitting areas of each color formed on the inner surface of the face of the picture tube, and a shadow mask having a curved effective surface with a large number of through holes. a mask and an electron gun that generates a plurality of electron beams, the electron beam is made to pass through a hole in the effective surface of the shadow mask so that the electron beam impinges on a predetermined light emitting area of the fluorescent screen. Color images are displayed in this way. In such a color picture tube, the If4 Michigami Shigegami electron beam 73 or more collides with the shadow mask, thermally expanding the shadow mask, and the landing position of the electron beam in the emission fr1 region shifts, causing deterioration of color purity. Various proposals have been made to suppress such mislandings caused by the so-called doming phenomenon. For example, Japanese Patent Application Laid-Open No. 60-54139 discloses that a ceramic layer is formed on the main surface of the shadow mask to apply residual tensile stress to the shadow mask to suppress doming of the shadow mask, and to reduce the thermal conductivity of the shadow mask. In Japanese Patent Publication No. 57-1882/1, an electron absorbing layer of low conductivity is formed corresponding to the non-emissive area on the surface of the fluorescent screen where the electron beam strikes. Some devices charge the electron absorption layer negatively to electrostatically correct the trajectory of the electron beam.

However, simply forming a ceramic layer on the main surface of the shadow mask is still insufficient in terms of suppressing mislanding. On the other hand, in the case of forming an electron absorption layer in the non-emissive area of a fluorescent screen, the first problem is that after landing due to the doming phenomenon, a decelerating electric field that becomes negatively charged begins to act, resulting in a time delay; The negatively charged part of the absorption layer is only the part where mislanding occurred, and its small area is insufficient as a deceleration electric field.Thirdly, it is not effective against mislanding due to doming in the early stage of operation.Fourthly, The problem is that the forming method is not suitable for Nissan in terms of work and precision.

(Problems to be Solved by the Invention) In this way, simply adding a ceramic layer or an electron absorption layer to the main surface of the shadow mask or the non-emissive area of the fluorescent screen will immediately respond to mislanding due to doming and prevent color shift. There is a problem in which the mislanding cannot be sufficiently corrected because it cannot be corrected or the portion is too small to be affected by the corrective action. An object of the present invention is to sufficiently suppress mislandish ink over the entire effective screen including the initial stage of operation.

[Structure of the Invention] (Means for Solving the Problems) The present invention has been made to solve the above problems, and includes a fluorescent screen, a shadow mask disposed close to the fluorescent screen, and a shadow mask disposed near the fluorescent screen. A color picture tube comprising at least an electron gun that emits an electron beam that passes through a hole in the mask and causes a phosphor on a screen to selectively emit light, the color picture tube including at least the center side of the shadow mask of the hole in the shadow mask. It has an electron absorption layer on the wall surface that is charged according to the electron flow density and deflects the electron beam.

The electron absorption layer can be formed on the main surface of the shadow mask on the electron gun side. It can also be formed on the wall surface of the through-hole that is opposite to the wall surface on the center side of the shadow mask. In that case, it is desirable that the maximum thickness of the electron absorption layer on the wall surface facing the center side be 175 mm or less of the maximum thickness of the electron absorption layer formed on the wall surface on the center side.

Furthermore, low conductivity W:AF3 that substantially transmits electrons can be provided on the main surface of the electron absorption layer on the electron gun side.

(Function) When an electron beam impinges on the electron absorption layer formed on the wall surface on the center side of the shadow mask (hereinafter referred to as the "center side wall surface") of the shadow mask through hole, this electron absorption layer has a strength corresponding to the electron flow density. The electron beam that is negatively charged and passes through the hole is repelled by this negatively charged part and corrects its trajectory so that it moves away from this part, that is, away from the center of the mask, and doming occurs in response to the electron flow density. Due to this phenomenon, the landing point of the electron beam, which tends to deviate from a predetermined landing point on the fluorescent screen in the direction of the tube axis, acts in a countervailing manner so that it does not return to the original accurate landing point.

(Example) Hereinafter, one embodiment of the present invention will be described in detail.

FIG. 4 shows a longitudinal section of a collar receiver tube according to the present invention. As is clear from FIG. 4, the vacuum envelope is composed of a panel (10) whose front portion has a substantially rectangular outer shape, a funnel-shaped funnel (12), and a neck (13). A fluorescent screen (14) consisting of a striped phosphor layer that emits red, green, and blue light is adhered to the inner surface of the panel (10), and the neck (13) of the panel (1G). Three electron beams arranged in a line along the horizontal axis and corresponding to red, green and blue (
A so-called in-line electron gun (16) that emits 15)
is installed.

Further, in a position close to and facing the fluorescent screen (14), a large number of slit-shaped through holes are arranged in the vertical direction, and a large number of the vertical arrangements are arranged in the horizontal direction. (17) is the mask frame (18
) is supported and fixed. Furthermore, the mask frame (18) is supported within the panel by being engaged with stud pins (20) embedded in the inner wall of the upright end of the panel (10) via elastic members (19). The three in-line array electron beams (15) are deflected by a deflection device (22) external to the funnel (12);
By scanning a rectangular area corresponding to a rectangular panel (10) and passing through a hole in a shadow mask (17), the selected light beam lands on a striped phosphor layer to reproduce a color image. ing. In addition, the electron beam is affected by external magnetic fields such as the earth's magnetism (it may not land accurately on the striped phosphor layer, and in order to prevent the color purity of the reproduced image from deteriorating, a funnel (
12) A magnetic shield (21) made of a ferromagnetic metal plate inside
) is locked through the frame (18).

The shadow mask (17) arranged close to and facing the fluorescent screen (14) has a coefficient of thermal expansion of 1.2X.
It is made of so-called cold-rolled steel whose main component is iron, which is as large as 10'/℃ and has a thickness of 0. IJllll” 0.371111
As shown in FIG. 1, for example, lead oxide (pbo
) is sealed and bonded by high-temperature heat treatment.

This electron absorption layer is formed as follows.

Before the panel (10) and funnel (12) are sealed together, crystalline lead borate glass dissolved in acetic butyl alcohol solution containing several percent nitrocellulose is applied to the center side of the shadow mask (17). A shadow mask (17) coated with this crystalline lead-covered Wa@glass is mounted inside the panel (10). After that, the panel (10) and the funnel (12) are placed on a predetermined frame and passed through a furnace with a maximum temperature of about 400°C and a holding time of 35 minutes or more to crystallize the lead borate glass. By shadow masking a low conductivity lead borate glass layer with a conductivity of approximately 1o-12Ω-1°1o-1 (17)
It is formed in the center side wall surface (17a) of the through hole (27). The method for applying this glass layer is, for example, by forming a large number of through holes using ordinary etching means, press-molding, and then
It can be formed by spray coating, at which time the spray nozzle is moved from the periphery to the center of the shadow mask.
By fixing the nozzle on the peripheral side of the shadow mask at an angle so as to tilt the mask and spraying it, an electron absorption layer can be formed on the wall surface on the center side of the through hole.

Regarding changes in the trajectory of the electron beam due to doming of the shadow mask when operating a color picture tube with such a configuration, Figures 1 and 3 show that the shadow mask (17) does not cause any doming phenomenon. The electron beam (15) in this state is configured to land at a predetermined position (42) on the fluorescent screen (14). Here, if the electron beam density incident on the shadow mask (17) increases and the shadow mask (17) is heated and a doming phenomenon occurs, that is, the shadow mask (17)
) is heated and moves to the position shown by the dashed line (17a) in FIG. 3, the landing point of the electron beam on the fluorescent screen (14) is at the position ( Move to 12a). In other words, the electron beam that should land at the original landing point (42) lands at the point (42) on the tube axis side due to the doming phenomenon.
2a), and landed at points (42) and (42a).
) exceeds the limit of the landing margin due to the arrangement of the light emitting phosphor groups of each color, deterioration of color purity occurs.

Here, in the case of the present invention, as shown in FIG. 1, a glass layer, that is, an electron absorption layer (31) is formed on the center side wall surface (17a) of the through hole of the shadow mask, and a part of it is exposed to the electron beam of the shadow mask. Since Q=I is located on the main surface (17b) on the impacting side, when the electron beam is deflected and scanned, the electron flow density (accordingly, it becomes negatively charged) is that this electron absorption layer is negatively charged due to the penetration of electrons. Thickness about average depth or more,
In this example, it has approximately 10 IJIn, which means that it has a secondary electron emission coefficient with respect to negative electron energy, usually 10 keV to 30 keV. Then,
This negative charge, especially the negative charge charged on the surface of the center side wall surface of the through hole (27), bends the trajectory of the electron beam [15c] moved by doming in a direction away from the tube axis (47), and bends the trajectory of the electron beam [15c] as shown by the solid line (15a). ).

Therefore, due to the doming phenomenon, the landing point (42a) of the electron beam that is about to move from a predetermined landing point (42) in the direction of the tube axis (47) is offset to return to the original landing point (42) again. Therefore, even if a doming phenomenon occurs, mislanding of the electron beam can be suppressed and reduced. In this way, since the electron absorption layer (31) is formed on the center side wall surface (17a) of the through hole of the shadow mask, when a large current that causes doming development occurs, electrons in various parts of the right effect surface of the shadow mask are absorbed. It is negatively charged in accordance with the flow density, and works more effectively in cooperation with the doming suppressing action that utilizes the low thermal conductivity of the electron absorption layer. In addition, as long as the picture tube is in operation, the electron absorption layer is constantly bombarded by electron beams and secondary electrons from the screen surface, etc. Compared to a similar screen in which an electron absorption layer is formed in the non-emissive area, the effective area is much larger, and there is almost no time delay for the suppression effect to occur.

Looking at the effect of reducing the amount of movement of the electron beam by this electron absorption layer, the results shown in FIG. 2 were obtained. That is, in FIG. 2, the vertical axis indicates the relative value of the movement of the electron beam based on the value when there is no electron absorption layer on the center side wall of the through hole, and the horizontal axis indicates the relative value of the electron absorption layer on the center side wall. It can be seen that the amount of electron beam movement can be reduced by coating the electron absorption layer. In experiments conducted by the present inventors, an electron absorption layer was applied to a 21-inch shadow mask type color picture tube with a thickness of 50 to 100JjI11, but in both cases, the amount of beam movement due to the bedoming phenomenon was 60 to 100% compared to the conventional one. We were able to keep it down to around 65%.

The important thing here is that the through hole (2) of the shadow mask (17)
7) The wall facing the center side of the mask (17C) (
The electron absorption layer should not be provided on the opposite side wall surface (hereinafter referred to as the opposite side wall surface). Assuming that an electron absorption layer is also formed on the opposite wall surface (17C) and is negatively charged as described above, the electron beam (15C) passing through the center of the through hole (27) of the shadow mask will pass through the through hole (27). In the area of , the influence of the electron absorption layer formed on the opposite side wall surface (17c) is greater than that of the electron absorption layer (31) formed on the center side wall surface (17a) due to the relationship with the incident angle of the electron beam with respect to the shadow mask. I will receive a lot of C. Therefore, the center side wall surface (1
This will cancel out the orbit correction effect of the electron beam due to the negative charge charged on the electron absorption layer (31) formed in 7a), or promote misland ink. Roughly,
If there is an electron absorption layer on the opposite wall surface, the electron absorption layer kicks the electron beam due to the relationship with the incident angle of the electron beam, and the beam projected onto the fluorescent screen may not be of the originally intended size or shape. turn into.

Next, another embodiment will be explained using FIG. 5.

As shown in FIG. 5, if an electron absorption layer (31) is also applied to the main surface of the shadow mask (17) on the electron gun side, this layer has low thermal conductivity, so it has the effect of roughly suppressing the doming phenomenon. Immersed in responsiveness. This embodiment also has the effect of suppressing mislanding due to the doming phenomenon, similar to the above-mentioned embodiments. Furthermore, another embodiment will be described using FIG. 6 (numerals in the figure indicate the same parts as those in FIGS. 1 and 5). That is, the electron absorption layer (3
1) is made of lead borate glass containing approximately 75w% lead oxide (Pbo), and has an electrical conductivity of approximately 10-14Ω-1 m-1.
The holes in the shadow mask (2) have almost insulating properties.
7) and the main surface (17b) of the side V mask on the electron gun side, and these form a continuous layer. Further, a coating layer (45) mainly made of barium, for example, is formed on the surface of the electron absorption layer (31) formed on the electron gun side main surface (17b). This coating layer mainly composed of barium can be a low conductivity layer that substantially transmits electrons, for example, a getter coating. This getter film is produced by placing a boat filled with a dispersion control getter, for example, a metal compound of Ba and A1 and Ni in a weight ratio of about 1:1, so as to face the shadow mask, and heating it with high frequency after exhausting the boat. can be formed. It goes without saying that this getter film has the property of adsorbing gas generated within the color picture tube. When the color picture tube having such a configuration was operated, the same effects as in the above-mentioned embodiments were obtained.

By the way, in the above-mentioned embodiment, it was stated that it is preferable that no electron absorption layer exists on the opposite side wall surface (17c), but it is very difficult to eliminate it at all in terms of manufacturing. However, according to the experimental results of the present inventors, it was confirmed that if the electron absorption layer formed on the wall surface on the center side of the mask is 175 or less, there is no influence on the deflection effect due to negative charging or other problems. For example, in a 21-inch color picture tube, as shown in FIG.
), it was confirmed that when an electron absorption layer (31b) with a thickness of 10 tm was applied, the amount of electron beam movement was within the permissible range.

Looking at the change in the thickness of the electron absorption layer on the opposite wall surface and the amount of electron beam movement, the results shown in FIG. 8 were obtained. That is, in FIG. 8, the vertical axis indicates that the thickness of the electron absorption layer (31b) on the opposite side wall is the thickness of the electron absorption layer (31b) on the center side wall.
) The amount of movement of the electron beam is shown as a relative value based on the value when the thickness is 175. It was found that the amount of electron beam movement is small if the thickness of the opposite side electron absorption layer is smaller than about 175 mm of the center side electron absorption layer. layer(
31), for example, when a locally high electron current density disappears, the negative charge charged on the electron absorption layer (31) must decrease in response to the change in the disappearance of doming and become GX. In other words, if the conductivity of the electron absorption layer is good, the negative charging phenomenon will not work sufficiently, and if it is bad, the electron absorption layer will be close to an insulator and the negative charging phenomenon will not be resolved within a predetermined period of time, thereby promoting mislanding. Become.

When an electron absorption layer is provided as in the first and second embodiments of the present invention, this electron absorption layer is substantially covered with the surface of the electron absorption layer as in the third embodiment. If a low conductivity layer (45) through which an electron beam can pass is provided, this phenomenon can be suppressed by changing the conductivity of the low conductivity layer (45). For example, according to experiments conducted by the present inventors, the amount of movement of the electron beam due to doming when operating the 21-inch color picture tube according to the third embodiment of the present invention was measured, and the results are shown in FIG. The following results were obtained. In this Figure 9, the vertical axis shows the relative value of the movement of the electron beam based on the value when 150 mg of getter is scattered at the center of the shadow mask with a 21-inch color picture tube, and the horizontal axis shows the relative value. The amount of getter coated per 1 cm formed on the surface of the lead borate glass layer provided on the electron gun side of the shadow mask is shown.

The measurement conditions were: anode high voltage Eb = 26 KV, anode current 1b = 1100 μ8, and a partial white pattern as shown in FIG. 10 was used as the screen reproduction pattern. In FIG. 10, the shaded area is black, that is, a non-light-emitting area.

In addition, *marks indicate measurement points. As shown in FIG. 9, the electron absorption layer (31 It can be seen that the density of charges temporarily charged on the surface of ) can be suppressed, and therefore, it is possible to optimally select the domin suppressing effect due to the charging. When this low conductivity layer is mainly made of barium, its thickness is 30 to 300 mm.
IM acknowledged that the initial objective would be achieved if the number of people was reduced to zero.

Of course, other metals, such as aluminum, may be used for this electron-transparent, low-conductivity layer, but if a metal other than Gerakhu is used, additional equipment is required to deposit it, so color image reception is difficult. The use of getter substances, which are essential for tubes, can be said to be very suitable for oral production.

In the present invention, crystalline lead borate glass is shown as a binder, but the present invention is not limited to this, and other binders such as zirconia alkoxide compounds,
For example, the object of the present invention can be fully achieved using Zr5i (OC411a).

[Effects of the Invention] As described above, according to the present invention, colors such as color shift and color unevenness can be sufficiently eliminated over the entire screen, not only during the initial operation of a color picture tube but also during localized or short-time large currents on the screen. Ir! degree deterioration can be prevented.

[Brief explanation of drawings]

FIG. 1 is an enlarged simplified diagram showing an embodiment of the present invention, FIG. 2 is a graph showing the thickness of an electron absorption diagram and the amount of beam movement, and FIG. 3 is a graph showing the operation of a color picture tube according to an embodiment of the present invention. 4 is a schematic cross-sectional view showing the structure of a color picture tube, FIG. 5 is an enlarged simplified view of a shadow mask without showing another embodiment according to the present invention, and FIG. 6 is a schematic diagram according to the present invention. FIG. 7 is an enlarged and simplified diagram of a shadow mask showing another embodiment. FIG. 8 is an enlarged and simplified diagram of a shadow mask showing another embodiment.
The figure is a graph of the amount of electron beam movement due to changes in the thickness of the electron absorption layer.
The graph showing fu, FIG. 10, is a simplified diagram showing the screen pattern at the time of measurement.

Claims (5)

[Claims] (1) A fluorescent screen, a shadow mask with a large number of through holes arranged close to the fluorescent screen, and an electron beam that selectively causes the fluorescent material of the screen to emit light through the shadow mask. In the color picture tube equipped with at least an electron gun, the shadow mask may include an electron absorption layer on a wall surface of at least the center side of the shadow mask of each through hole, which is charged according to the electron flow density and deflects the electron beam. Features a color picture tube. (2) The color picture tube according to claim 1, wherein the electron absorption layer is formed on the main surface of the shadow mask on the electron gun side. (3) The color picture tube according to claim 2, further comprising an electron absorption layer on a wall surface opposite to the wall surface on the center side of the through-hole shadow mask. (4) The maximum thickness of the electron absorption layer formed on the wall surface on the center side of the through-hole shadow mask and the opposite wall surface is 1/5 of the maximum thickness of the electron absorption layer formed on the wall surface on the center side. A color picture tube according to claim 3, which is as follows. (5) A color picture tube according to claim 2 or 3, which has a low conductivity layer that substantially transmits electrons on the surface of the electron absorption layer on the electron gun side.