JPH05325818A - Shadow mask body structure for color cathode-ray tube - Google Patents

Abstract

(57) [Abstract] [Purpose] A shadow mask structure for a color cathode ray tube having no color shift is obtained by using a light-weight press frame formed by press molding. A tension collar mainly composed of a shadow mask 6 to which tension is applied, a substantially rectangular mask frame 5 that supports the shadow mask 6, and a spring 4 that holds the mask frame on a panel. The mask frame 5 of the shadow mask structure 12 for a cathode ray tube
[Effect] The mask frame 5 is deformed slightly into a barrel shape, and the shadow mask 6 is thermally deformed during operation of the cathode ray tube so that the mask frame 5 is almost pincushion-shaped. The amount of deformation in the direction returning to the rectangular shape is also significantly reduced, and the color shift is significantly suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a television picture tube,
The present invention relates to a shadow mask structure forming a color cathode ray tube used for a display device of an information terminal device.

[0002]

2. Description of the Related Art Generally, a shadow mask type cathode ray tube is
Usually, a fluorescent screen on which phosphor triplets of three primary colors of red, green, and blue are arranged, an electron gun for emitting an electron beam corresponding to each of the three primary color phosphors, and an electron beam of a round shape, a slot, a slit, or the like. A shadow mask structure having a passage hole is housed in a vacuum envelope (tube).

FIG. 3 is a cross-sectional view for explaining the structure of a shadow mask type cathode ray tube, wherein 1 is a panel 1-1 and a neck 1.
-2, a tube made of funnel 1-3, 2 a skirt portion of the panel 1, 3 pins, 4 springs, 5 mask frame, 6 shadow mask, 7 electron gun, 8 electron beam, 9 A deflection coil, 10 is a color fluorescent screen, 11 is a face plate portion, and 12 is a shadow mask structure.

In FIG. 1, the tube 1 comprises a panel 1-1 carrying a color phosphor screen 10, a neck 1-3 accommodating an electron gun, and a funnel 1-2 connecting the panel and the neck. The electron gun 7 is arranged symmetrically with respect to the central axis (tube axis) of the tube body 1, and the three emitted electron beams 8 form a shadow mask structure 12 arranged immediately before the fluorescent screen. By passing through the electron beam passage hole of the mask 6, color selection is performed, and a fluorescent body of a predetermined color is landed and excited to reproduce an image.

4A and 4B are explanatory views of a conventional shadow mask structure. FIG. 4A is a plan view, FIG. 4B is a horizontal sectional view taken along line AA of FIG. 4A, and FIG. FIG. 8B is a vertical cross-sectional view taken along the line BB of FIG. As shown in FIG. 1, the shadow mask structure 12 constitutes a panel of the tubular body 1 including a shadow mask 6 having a large number of electron beam passage holes, a mask frame 5 for supporting the shadow mask 6 in a stretched manner, and the mask frame. It mainly consists of a spring 4 (FIG. 3) suspended and held on a pin 3 which is planted on the inner wall of the skirt portion 2.

A large number of electron beam passage holes are formed in the shadow mask 6. As the shape of the electron beam passage holes, it is known that round, slot-shaped, or slit-shaped pores are arranged on the entire surface of the shadow mask at substantially equal intervals. With a shadow mask that has circular holes,
For example, holes having a diameter of 0.08 mm can be formed at a pitch of 0.2 mm. As is well known, when the lines connecting the centers of the holes intersect at an angle of 60 °, all the holes are arranged at equal intervals.

Returning to FIG. 3, the red color of the color phosphor screen 10,
The phosphor triplets of the three primary colors of green and blue and the electron beam passage holes of the shadow mask 6 are regularly arranged so that each electron beam of the three electron beams 8 impacts only the phosphor of each emission color. Is located in. Funnel 1 of tube 1
A deflection coil 9 is mounted on the outer side of 3 to color the three electron beams 8 emitted from the electron gun 7 so as to be concentrated at the center of the inner surface of the face plate portion 11 with a mutual spacing of 5.5 mm. A color image is formed by scanning the fluorescent screen 10 horizontally and vertically in two dimensions.

In order to achieve good color reproduction, a large number of electron beam passage holes formed in the shadow mask 6 and the corresponding phosphor triplets of red, green, and blue of the color phosphor screen 10 relative to each other. The positional relationship has a predetermined matching relationship,
It is necessary that the electron beam that has passed through the electron beam passage hole of the shadow mask 6 accurately land on a predetermined phosphor.

However, the electron beam passes through the shadow mask 6 at a rate of 15 to 20%, and most of the other electron beams impinge on the shadow mask 6 and are expanded by heating. This thermal expansion increases when the electron beam is increased to obtain a particularly bright screen. As a result, the landing position of the electron beam on the phosphor is greatly changed, and the color purity is deteriorated.

As one of the methods for preventing the deterioration of the color purity due to the thermal expansion of the shadow mask by the electron beam, a method of applying tension to the shadow mask has been proposed. For example, JP-A-59-167936 and JP-A-62-133645 are known to disclose conventional techniques for applying a tension to the shadow mask to avoid the deterioration of color purity due to the thermal expansion. There is.

According to the technique disclosed in Japanese Patent Laid-Open No. 167936/1984, a shadow mask to which a tension is applied is masked while the mask frame for attaching the shadow mask is compressed from the side surface toward the center of the mask frame. It is characterized by being fixed to the frame. Further, in Japanese Patent Laid-Open No. 62-133645, the shadow mask and the mask frame are made of a metal material having a bending point in a thermal expansion curve up to 500 ° C., and the shadow mask has a low bending point temperature. The material is characterized in that a material having a high bending point temperature is used for the mask frame.

[0012]

In the above prior art, when the shadow mask is attached to the mask frame by applying tension, the mask frame 5 is curved in a pincushion shape as shown by the dotted line in FIG. Is in balance. During operation of the color cathode ray tube, when the shadow mask 6 is heated by the electron beam hitting the shadow mask and thermally expanded, the mask frame 5 is deformed in a direction returning to the original shape shown by the solid line. As a result, the slack due to thermal expansion of the shadow mask 6 is absorbed, and the color shift phenomenon due to the slack of the shadow mask can be significantly reduced.

Strictly speaking, however, the position of the electron beam passage hole of the shadow mask 6 fixed to the mask frame 5 is displaced along with the deformation of the mask frame 5. That is, due to the deformation of the mask frame 5, the electron beam passage hole near the outer circumference on the long axis AA and the short axis BB is displaced outward, and the landing position of the electron beam passing through the electron beam passage hole is shifted. Shifts outward. The amount of this displacement is greatest near the outer circumference on the major axis and the minor axis. For this reason,
There was a problem of causing deterioration of color purity.

An object of the present invention is to solve the above-mentioned problems of the prior art, and suppresses the landing shift of the electron beam generated as a result of displacement of the shadow mask to which tension is applied due to thermal expansion, thereby reducing color. It is to provide a shadow mask structure for a color cathode ray tube with improved purity.

[0015]

In order to achieve the above object, the present invention provides a shadow mask 6 to which tension is applied,
In a tension-type shadow mask structure 12 for a color cathode ray tube mainly composed of a substantially rectangular mask frame 5 for supporting the shadow mask 6 and a spring 4 for holding the mask frame on a panel, It is characterized in that the outer periphery is tightened with a metal band 13.

In order to make the tightening force of the mask frame 5 by the metal band 13 constant, it is preferable that the material of the metal band is mild steel. Further, in order to avoid the deterioration of the characteristics of the shadow mask structure 12 in the heat treatment process during manufacturing of the cathode ray tube, the material of the mask frame 5 is set to a material having a smaller thermal expansion coefficient than the metal band 13 and the shadow mask 6. Is desirable. Therefore, it is suitable to use ferritic stainless steel containing Fe and Cr of 10 to 32 wt% as main components for the mask frame.

[0017]

With the structure of the present invention, the substantially rectangular mask frame 5 receives a large compressive force in the central direction at its four corners, and its two long sides and two short sides are slightly deformed outward. .. That is, the mask frame 5 is slightly deformed into a barrel shape. When the shadow mask 6 to which tension is applied is stretched and fixed to the mask frame 5 in this state, the pincushion-shaped shadow mask 6 as shown in FIG. The deformation is significantly reduced.

As a result, when the cathode ray tube is operated, the shadow mask 6 is thermally deformed (thermally expanded) by being hit by the electron beam, and the deformation amount of the mask frame 5 is returned from the pin cushion shape to the original substantially rectangular shape. Is also significantly reduced, and color shift is significantly suppressed. The material of the metal band 13 does not need to be particularly limited, but if heat-treated mild steel is used,
A constant compressive force can be applied to the mask frame 5 within a relatively wide range of elongation after yielding.

Further, the material of the mask frame 5 is selected in order to prevent the compressive force from being lowered due to excessive strain of the metal band 13 in the heat treatment process during the manufacture of the cathode ray tube.
It is desirable that the material has a coefficient of thermal expansion smaller than 3, and in consideration of cost and the like, iron (Fe) and chromium (C
r) Ferritic stainless steel containing 10 to 32% as a main component is suitable. In this case, it is possible to avoid the occurrence of excessive strain in the heat treatment process, and to suppress the reduction of the compressive force applied to the mask frame 5.

[0020]

Embodiments of the present invention will now be described in detail with reference to the drawings. 1 is a perspective view illustrating an embodiment of a shadow mask structure for a color cathode ray tube according to the present invention, and the same reference numerals as those in FIGS. 3 and 4 correspond to the same portions. The shadow mask structure 12 of the embodiment shown in FIG.
An annular metal band 13 is wound around the outer periphery of the substantially frame-shaped mask frame 5 having a substantially rectangular shape, which constitutes the shadow mask fixing portion, and the metal frame 13 compresses and tightens the mask frame 5.

The tightening of the mask frame 5 with the metal band 13 is preferably performed by a known shrink fitting method. 2 (a) is a front view for explaining the configuration of the shadow mask structure shown in FIG. 1 in detail, (b) is a sectional view taken along line AA of (a), FIG.
(C) It is a BB sectional view of (a). The spring 4 is omitted in FIG.

The metal band 13 is made of annealed mild steel,
After tightening the mask frame 5 with this metal band 13,
The shadow mask 6 to which tension is applied is stretched and fixed to the outer periphery of the mask frame. By tightening the mask frame 5 with the metal band 13, the four corners of the mask frame 5 receive a large compressive force in the central direction, and the two long sides and the two short sides are slightly deformed to the outside, respectively. 5 is deformed into a barrel shape as a whole.

In the present embodiment, the metal band 13 is a ribbon of mild steel having a plate thickness of 0.5 mm and a width of 12 mm, the inner peripheral length of which is, for example, 20 mm cathode ray tube, less than the outer peripheral length of the mask frame 5. It is formed into a ring that is 4% smaller and is fixed to the outer periphery of the mask frame 5 by shrink fitting as described above. The amount of decrease in the minor axis diameter and the major axis diameter of the mask frame 5 caused by stretching and fixing the shadow mask 6 to which tension is applied to the mask frame 5 thus tightened with the metal band 13 is 0.1m each against 0.3mm and 0.1mm without tightening
m, 0.03 mm, which is about 1/3.

As a result, in the operation of the completed color cathode ray tube, the deviation amount of the landing of the electron beam in the vicinity of the outer circumference on the short axis and the vicinity of the outer circumference on the long axis when a full surface raster with a brightness of 100 cd / m ² is formed. , 8 μm and 5 μm, respectively, compared with 25 μm and 15 μm when the metal band 13 is not tightened, respectively, and the landing deviation is greatly reduced.

As described above, by tightening the metal band 13 on the outer periphery of the mask frame 5, even if an inexpensive and lightweight mask frame manufactured by press molding is used, the color shift is small and the brightness is high and the resolution is high. A color cathode ray tube can be easily manufactured. In this example,
Although a mild steel having a plate thickness of 0.5 mm and a width of 12 mm is used as the metal band, the present invention is not limited to this, and the plate thickness and width are the strength, shape and shadow of the mask frame to be tightened. The optimum value may be selected according to the tension applied to the mask.

The material of the metal band is mild steel which has a constant stress even when it is elastically deformed or deformed so that a constant compression force is easily applied when the annular metal band is tightened on the mask frame by shrink fitting. However, the present invention is not limited to this, and may be any one that can control the compression force for tightening the mask frame. Further, in the present embodiment, the mask frame is made of ferritic stainless steel containing Fe and Cr of 10 to 32% as main components. However, this is an excessive strain on the metal band and the shadow mask in the heat treatment process during the manufacture of the cathode ray tube. This is to reduce the thermal expansion of the mask frame in order to prevent the compressive force applied to the mask frame and the tension of the shadow mask itself from decreasing.

The average coefficient of thermal expansion from room temperature to 450 ° C is 140 × 10 ^-7 / ° C for mild steel and 11 for the ferritic stainless steel which is the mask frame material of this embodiment.
It is as small as 0 × 10 ⁻⁷ / ° C, and it is possible to suppress excessive strain between the metal band and the shadow mask due to the difference in heat capacities of the respective members when the temperature is lowered in the heat treatment step. However, if the temperature lowering rate in the heat treatment step is made sufficiently small, this problem does not occur. Therefore, if the manufacturing process is adequately controlled, the mask frame material may be a material other than those used in the above-mentioned examples. Play.

Further, the electron beam passage hole in the shadow mask is not limited to the dot type of the round hole, but the shadow mask fixed is fixed to the slot type of the long hole or the grill type having the slit without the bridge in the horizontal direction. Although there are some differences in the modified form of the mask frame at this time, the effect obtained by tightening the mask frame with the metal band is similar.

The mask frame forming the shadow mask structure is not limited to the shape of the embodiment shown in the figure, and the same effect can be obtained if the mask frame has a substantially rectangular shape.

[0030]

As described above, according to the present invention,
By fixing the shadow mask to which tension has been applied after tightening the mask frame with a metal band, deformation of the mask frame during the operation of the cathode ray tube is suppressed, the deviation of the landing of the electron beam is greatly reduced, and a large current is applied. It is possible to realize a cathode ray tube having a good color purity even at the time of high brightness operation by flowing it with an inexpensive and lightweight mask frame.

Then, a certain compression force can be applied to the mask frame by shrink-fitting a metal band made of mild steel and preliminarily annular. Further, by using stainless steel (ferritic stainless steel) whose main components are Fe and Cr of 10 to 32% as the material of the mask frame, the excess of the metal band and the shadow mask in the heat treatment step having the temperature gradient of the cathode ray tube can be achieved. It is possible to prevent characteristic deterioration due to distortion.

[Brief description of drawings]

FIG. 1 is a perspective view illustrating one embodiment of a shadow mask structure for a color cathode ray tube according to the present invention.

2 (a) is a front view showing in detail a structure of a shadow mask structure for a color cathode ray tube according to the present invention; FIG.
It is an AA sectional view of (a), and is a BB sectional view of (c) (a).

FIG. 3 is a cross-sectional view illustrating the structure of a shadow mask type color cathode ray tube.

4A and 4B are explanatory views of a shadow mask structure according to a conventional technique. FIG. 4A is a plan view, FIG. 4B is a horizontal sectional view taken along line AA of FIG. 4A, and FIG. FIG. 6 is a vertical cross-sectional view taken along the line BB.

[Explanation of symbols]

 1 Tubular Body 1-1 Panel 1-2 Neck 1-3 Funnel 2 Skirt 3 Pin 4 Spring 5 Mask Frame 6 Shadow Mask 7 Electron Gun 8 Electron Beam 9 Deflection Coil 10 Color Fluorescent Surface 11 Face Plate 12 Shadow Mask Structure 13 Metal band

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kawa ▲ Saki ▼ Hiro, 3681 Hayano, Mobara-shi, Chiba Hitachi Device Engineering Co., Ltd. (72) Inventor Takao Kawamura 3300, Hayano, Mobara, Chiba Hitachi Ltd. Within

Claims (1)

[Claims] 1. A tension type color cathode ray tube mainly composed of a shadow mask to which tension is applied, a substantially rectangular mask frame for supporting the shadow mask, and a spring for holding the mask frame on a panel. In the shadow mask structure, the shadow mask structure is characterized in that the outer periphery of the mask frame is tightened with a metal band.