JP2000100344A - Color picture tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color picture tube that prevents thermal expansion of a shadow mask from causing degradation in color purity, independently of the material of a mask body. SOLUTION: This color picture tube has a shadow mask 20, comprising a substantially rectangular mask body 21 and a substantially rectangular mask frame 22 mounted to he periphery of this mask body, the mask frame is constituted with two U-shaped first frame pieces 23 and two second frame pieces 24 having thermal expansion coefficient larger than that of the first frame pieces, the second frame pieces are arranged on the both sides in the long axis direction of the mask frame and the first frame pieces are fixed to the both sides of the second frame pieces to form a substantially rectangular frame, and an intermediate portion 25 between the long axis end and the diagonal axis end of this mask frame is mounted to the periphery of the mask body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color picture tube, and more particularly, to a color picture tube in which deviation of beam landing due to doming of a shadow mask is suppressed.

[0002]

2. Description of the Related Art Generally, a color picture tube has an envelope composed of a substantially rectangular panel 1 and a funnel-shaped funnel 2 as shown in FIG. ,
Phosphor screen 3 comprising a three-color phosphor layer that emits red light
A substantially rectangular shadow mask 4 is arranged near the phosphor screen 3 inside. The shadow mask 4 is used for the phosphor screen 3.
A substantially rectangular mask body 5 having a large number of apertures formed on a surface facing the mask body 5 and a substantially rectangular mask frame 6 attached to the periphery of the mask body 5 are provided on the panel 1. Stud pin 7 and mask frame 6
And is supported by a spring member 8 which is fixed to the stud pin 7. Meanwhile, funnel 2
Three electron beams 10B, 10G, 10R in the neck 9
An electron gun 11 for emitting (only 10G is shown) is provided. Then, the three electron beams 10B, 10G, 10R emitted from the electron gun 11 are deflected by a deflecting device (not shown) mounted outside the funnel 2, and the fluorescent material is passed through the aperture of the mask body 5. A color image is displayed by scanning the screen 3 horizontally and vertically.

The shadow mask 4 has three electron beams 10B and 10B passing through openings in a mask body 5 at different angles.
G and 10R are color selection electrodes for landing on the corresponding three-color phosphor layers. In order to display an image with good color purity on the phosphor screen 3, the phosphor screen 3 and the mask body 5 must be combined. It is necessary to maintain a predetermined matching relationship, and it is necessary to maintain the matching relationship during the operation of the color picture tube.

However, in general, in a color picture tube, an electron beam which reaches the phosphor screen 3 through an opening of the mask body 5 due to the operation principle is formed by three electron beams 10B, 10G and 10R emitted from the electron gun 11. The other electron beam is not more than 1/3, and the other electron beam mainly collides with the mask body 5 to heat it. However, even when heated, the peripheral portion of the mask body 5
Since the heat capacity is large and the surface is in contact with the blackened mask frame 6, heat moves to the mask frame 6 by radiation and conduction, and the temperature of the peripheral portion of the mask main body 5 becomes lower than that of the central portion. Therefore, the center of the mask body 5 is relatively heated. As a result, in the mask main body 5 made of, for example, low-carbon steel having a large thermal expansion coefficient, as shown in FIG. 5, the electron beam 10 (10B, 10B, 10B) passing through the opening 13 of the mask body 5 changes.
10G, 10R) do not land accurately on a given phosphor layer, leading to deterioration of color purity.

[0005] Such thermal expansion of the mask main body 5 is caused by operating the color picture tube continuously for a long time.
As a result, the mask frame 6 gradually expands due to the heat transfer, and the mask frame 6 turns in a direction to ease the doming of the mask body 5 immediately after the color picture tube operation starts. However, since the temperature of the mask frame 6 does not reach the same temperature as the mask body 5, the deterioration of the color purity due to the doming does not completely disappear.

There is a method for preventing the color purity from being degraded due to the thermal expansion of the shadow mask by the shape of a spring member supporting the shadow mask. However, when the mask body is doming, the deterioration of the color purity around the mask body due to the thermal expansion of the mask frame and the deterioration of the color purity inside the periphery due to the doming of the mask body are completely and simultaneously completed. It cannot be eliminated.

Various measures and proposals have conventionally been made to prevent the deterioration of color purity due to such doming.

As one of the methods, there is one in which a mask main body is formed of an invar material having a small coefficient of thermal expansion so that deformation due to doming is reduced even when heated by collision of an electron beam.

Further, a mask body made of invar material and a mask frame are welded at a middle portion of a short side between a horizontal axis end and a diagonal axis in addition to a horizontal, vertical and diagonal axis. is there. In this way, when the mask body and the mask frame are welded at the middle part of the short side between the horizontal axis end and the diagonal axis end,
When the mask body and the mask frame are both thermally expanded because the thermal expansion coefficient of the mask body made of amber material is smaller than the thermal expansion coefficient of the mask frame, the mask body has a tube axis near the horizontal axis end. In the direction (perpendicular to the horizontal axis), the doming near the horizontal axis end of the mask body is suppressed, and the deterioration of color purity is reduced.

However, when an amber material is used for the mask body as in the above-mentioned shadow mask, the cost of the mask body is higher than that of a normal shadow mask made of low carbon steel. Further, the means for welding at the intermediate portion of the short side between the horizontal axis end and the diagonal axis end is effective when the thermal expansion coefficients of the mask body and the mask frame are different. Is not effective for low cost color picture tubes made of low carbon steel.

[0011]

As described above, in order to prevent the color purity from deteriorating due to the thermal expansion of the shadow mask, the mask body is formed of an amber material having a small thermal expansion coefficient, and the mask body is formed by the collision of an electron beam. What reduced deformation due to doming even when heated, furthermore, the mask body and mask frame made of amber material, horizontal, vertical,
Some are welded on the diagonal axis and in the middle of the short side between the horizontal axis end and the diagonal axis end.

However, when the mask body is formed of an invar material, the cost of the mask body is higher than that of a normal shadow mask made of low carbon steel. Further, the means for welding at the middle of the short side between the horizontal axis end and the diagonal axis end is not effective for a low-cost color picture tube in which both the mask body and the mask frame are formed of low carbon steel. There is a problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has no problem in color reception due to thermal expansion of a shadow mask and maintaining good beam landing characteristics regardless of the material of the mask body. The purpose is to construct a tube.

[0014]

Means for Solving the Problems A phosphor screen provided on the inner surface of a substantially rectangular panel and a substantially rectangular shadow mask arranged at a predetermined distance from each other, and the shadow mask faces the phosphor screen. In a color picture tube comprising a substantially rectangular mask body provided with a large number of apertures on the surface to be formed, and a substantially rectangular mask frame attached to the periphery of the mask body, the mask frame is
It is composed of two U-shaped first frame pieces and two second frame pieces having a larger coefficient of thermal expansion than the first frame pieces, and the second frame pieces are disposed on both sides in the major axis direction of the mask frame. And the first frame piece is fixed to both sides of the second frame piece to form a substantially rectangular frame, and an intermediate portion between the long axis end and the diagonal axis end of the mask frame is attached to the peripheral portion of the mask body. .

Further, the second frame piece is arranged on the long axis of the mask frame, and the two first frame pieces are arranged symmetrically with respect to the long axis.

The first frame piece was made of low carbon steel and the second frame piece was made of stainless steel.

Further, the intermediate portion of the mask frame attached to the peripheral portion of the mask body is located on the first frame piece.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows a color picture tube which is one embodiment of the present invention. This color picture tube has an envelope composed of a substantially rectangular panel 1 and a funnel-shaped funnel 2. On the inner surface of the panel 1, a phosphor screen 3 composed of a three-color phosphor layer that emits blue, green, and red light is provided. A substantially rectangular shadow mask 20, which will be described later, is arranged near the phosphor screen 3 and inside thereof. On the other hand, in the neck 9 of the funnel 2, three electron beams 10B
, 10G, 10R (only 10G is shown). Then, the three electron beams 10B, 10G, 10R emitted from the electron gun 11 are deflected by a deflecting device (not shown) mounted outside the funnel 2, and are selected by opening the shadow mask 20. A color image is displayed by scanning the phosphor screen 3 horizontally and vertically.

The shadow mask 20 has a plate thickness of 0.1 mm having a large number of apertures formed on the surface facing the phosphor screen 3.
Substantially rectangular mask body 2 made of low carbon steel of about 2 mm
1 and a substantially rectangular mask frame 22 having a thickness of 0.4 to 1.2 mm and attached to the periphery of the mask body 21.
And a spring member 8 attached to the mask frame 22 and locked to the stud pin 7.

In particular, in this embodiment, as shown in FIG. 1, the mask frame 22 is composed of two identically shaped U-shaped first frame pieces 23 made of low carbon steel. The second frame piece 24 includes two second frame pieces 24 made of stainless steel or the like having a larger coefficient of thermal expansion than the piece 23. The first frame pieces 23 are provided on both sides of the second frame piece 24 with the second frame piece 24 interposed therebetween. Is fixed.

That is, in the mask frame 22 of this embodiment, the second frame piece 24 is arranged on the horizontal axis (X axis, long axis) of the mask frame, and the second frame piece 24 is axially symmetrical along the horizontal axis of the mask frame. One frame piece 23 is fixed to both sides of the second frame piece 24, and is formed in a substantially rectangular frame shape as a whole. Particularly, in the shadow mask 20, at least an intermediate portion between the horizontal axis end and the diagonal axis end of the mask frame 22 is welded to a peripheral portion of the mask main body 21. The intermediate welding point 25 is preferably located on the first frame piece 23.

With the above configuration, even if the shadow mask 20 is heated by the collision of the electron beams 10B, 10G, 10R, doming of the mask body 21 is suppressed, and the alignment between the phosphor screen 3 and the mask body 21 is suppressed. A color picture tube which maintains the relationship and is unlikely to cause deterioration in color purity of a white screen can be formed.

That is, the mask body of the color picture tube is
During operation, the electron beam is heated to about 80 ° C. by the collision of the electron beam and thermally expanded, the position of the aperture for selecting the three electron beams changes, the landing of the three electron beams on the three-color phosphor layer is shifted, and the purity drift is reduced. (See FIG. 6). The heat of the heated mask body is transmitted to the mask frame when the color picture tube is continuously operated for a long time, and the mask frame also thermally expands.

In this case, like the mask frame 22, the second frame piece 24 having a large thermal expansion coefficient on the horizontal axis.
Is disposed, and the mask body 21 and the mask frame 22 are welded at an intermediate portion between the horizontal axis end and the diagonal axis end of the mask frame 22, preferably on the first frame piece 23. As compared with the frame, due to the large thermal expansion of the second frame piece 24, it is possible to increase the displacement of the welding point 25 between the mask body 21 and the mask frame 22 in the vertical axis direction as shown by an arrow 27 in FIG. it can. Thereby, the vicinity of the horizontal axis end of the mask main body 21 is greatly pulled in the vertical direction, and as shown by the broken line in FIG. 3, the mask main body 21 that is doming is returned to the original state.

Therefore, by configuring the shadow mask 20 as described above, the matching relationship between the phosphor screen 3 and the mask main body 21 inside the peripheral portion of the mask main body 21 is maintained, and the color of the white screen is maintained. Purity can be hardly deteriorated.

In this case, the deterioration of the color purity in the peripheral portion of the mask body 21 due to the thermal expansion of the mask frame 22 is prevented by means such as appropriately setting the shape of the spring member 7 supporting the shadow mask 20. can do.

In the above embodiment, the case where the mask body is made of low-carbon steel is described. However, the present invention is adapted to the case where the mask body is made of a low thermal expansion material such as an invar material, so that the doming is reduced. The color purity of a white screen can be improved.

[0029]

As described above, when the shadow mask is formed, even if the mask body is heated by the collision of the electron beam, doming of the mask body is suppressed, and the matching relationship between the phosphor screen and the mask body is reduced. A color picture tube which holds the color picture tube and is hardly deteriorated in color purity can be formed.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a shadow mask of a color picture tube according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a color picture tube according to an embodiment of the present invention.

FIG. 3 is a view for explaining thermal expansion of a mask frame of the shadow mask.

FIG. 4 is a diagram showing a configuration of a conventional color picture tube.

FIG. 5 is a view for explaining a landing deviation due to thermal expansion of a mask body of a conventional color picture tube.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Panel 3 ... Phosphor screen 20 ... Shadow mask 21 ... Mask main body 22 ... Mask frame 23 ... 1st frame piece 24 ... 2nd frame piece 25 ... Middle part

Claims (4)

[Claims] 1. A phosphor screen provided on an inner surface of a substantially rectangular panel and a substantially rectangular shadow mask arranged at a predetermined distance from the phosphor screen, and the shadow mask is provided on a surface facing the phosphor screen. In a color picture tube comprising a substantially rectangular mask body provided with a large number of apertures and a substantially rectangular mask frame attached to a peripheral portion of the mask body, the mask frame has two U-shapes. And two second frame pieces having a larger coefficient of thermal expansion than the first frame piece. These second frame pieces are arranged on both sides in the major axis direction of the mask frame, and the first frame piece Pieces are fixed to both sides of the second frame piece to form a substantially rectangular frame, and an intermediate portion between a long axis end and a diagonal axis end of the mask frame is attached to a peripheral portion of the mask body. Color picture tube, characterized in that it is. 2. The apparatus according to claim 1, wherein the second frame piece is arranged on the long axis of the mask frame, and the two first frame pieces are arranged symmetrically with respect to the long axis. Color picture tube. 3. The first frame piece is made of low carbon steel, and the second frame piece is made of stainless steel.
A color picture tube as described. 4. The color picture tube according to claim 1, wherein an intermediate portion of the mask frame attached to a peripheral portion of the mask body is located on the first frame piece.