JPH0917348A - Cathode ray tube - Google Patents

Abstract

(57) Abstract: A cathode ray tube having an improved shadow mask structure is provided. A first shadow mask is an electron beam.
A second shadow mask 118 is further provided on the inner surface of the first shadow mask 18 in order to prevent thermal expansion of the first shadow mask 18 by the predetermined electron beam 15 that collides with the first shadow mask 18. Shut off.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode ray tube, and more particularly to a cathode ray tube having an improved shadow mask structure.

[0002]

2. Description of the Related Art Generally, a shadow mask having a uniform thickness and a large number of beam passage holes arranged in a uniform manner is provided inside a front funnel of a color cathode ray tube. This shadow mask selectively passes only a predetermined electron beam among the electron beams emitted from the electron gun provided at the neck of the cathode ray tube, and the passed electron beam is formed on the inner surface of the funnel of the cathode ray tube. The phosphors are made to emit light to realize red, green and blue.

FIG. 3 is a sectional view showing a conventional cathode ray tube. As shown in the figure, the cathode ray tube is a vacuum container including a panel 10, a funnel 11 and a neck 12.
The inner surface of the panel 10 is provided with a screen 14 coated with phosphors that emit red, green, and blue light, respectively. The neck 12 is provided with electron guns 13 arranged in a line along the horizontal axis of the panel 10 and emitting three electron beams 15 corresponding to red, green and blue.

The frame 16 has a shadow mask 18 in which a large number of beam passage holes 21 are formed in the horizontal and vertical directions.
And is provided in the vicinity of the screen 14. The frame 16 is supported by one end of a hook spring 20, and the other end of the hook spring 20 is connected to a stud pin 17 provided on the inner surface of the panel 10.

The electron beam 15 is deflected by the deflecting device 9 outside the funnel 11 and scanned on the screen 14 through the beam passage hole 21 of the shadow mask 18. The electron beam 15 scanned on the screen 14 causes the phosphor coated on the screen to emit light.

In such a cathode ray tube, the electron gun 13
Of the electron beam 15 emitted from the shadow mask 1
The effective electron beam that passes through 8 and reaches the screen 14 to emit the phosphor is 1/3 or less, and the remaining electron beam collides with the shadow mask 18 and heats the shadow mask 18 to about 80 ° C. to expand it. .

The shadow mask 18 is generally made of iron having a relatively large coefficient of thermal expansion and having a thickness of about 0.2 mm, and a solid frame 16 having a thickness of about 1 mm. The area around it is fixed.

On the other hand, the electron beam 15 impinging on the shadow mask 18 heats and expands the shadow mask 18, so that the phosphor screen 14 and the shadow mask 1 are exposed.
The interval with 8 changes. If this interval exceeds the allowable value,
The electron beam 15 is not accurately landed on the three color phosphors of the screen 14 by the deformed beam passage hole 21 of the shadow mask 18. That is, the color purity deteriorates due to mislanding.

The deterioration of the color purity due to the thermal deformation of the shadow mask 18 becomes more serious as the resolution increases in a large color cathode ray tube. Usually 25 "or more for home use,
In the case of industrial use, deterioration of color purity occurs in a cathode ray tube of 15 ″ or more.

In order to solve this, the thermal deformation rate is reduced by coating the shadow mask with a substance having a high electron reflectance such as bismuth, or by using a high-cost shadow mask having a small coefficient of thermal expansion. ing. Then, using the hook spring 20, the shadow mask 1
The method of correcting the thermal deformation of No. 8 is also adopted.

However, using a shadow mask having a low coefficient of thermal expansion or coating the shadow mask with a substance having a high reflectance causes a problem of high cost. In addition, there is a problem that the correction is excessive when the deformation of the shadow mask is corrected by using the hook spring.

[0012]

In view of the above-mentioned problems, an object of the present invention is to provide a cathode ray tube capable of effectively correcting thermal deformation of a shadow mask.

[0013]

To achieve the above object, a cathode ray tube according to the present invention is provided in a panel, a funnel sealed to the panel, and a neck portion of the funnel to emit an electron beam. An electron gun, a screen provided inside the panel and coated with a phosphor, a deflector provided outside the funnel to deflect the electron beam, and provided inside the screen to perform the deflection. A first shadow mask in which a large number of first beam passage holes for selectively passing electron beams are formed, and the first beam passage holes are provided inside the first shadow mask. Is further provided with a second shadow mask having a large number of second beam passage holes formed at positions corresponding to.

The size of the second beam passage hole is larger than that of the first beam passage hole.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

FIG. 1 is a sectional view showing a cathode ray tube according to the present invention. As shown in the figure, the cathode ray tube has a panel 1
0, funnel 11 and neck 12 are included.

On the inner surface of the panel 10 is provided a screen 14 coated with phosphors which emit red, green and blue light respectively, and on the neck 12 is provided an electron gun 13 for emitting three electron beams 15. . And the funnel 11
A deflection device 9 for deflecting the electron beam 15 toward a predetermined portion of the screen 14 is provided outside the device.

A large number of first beam passing holes 21 are formed in the first shadow mask 18 provided inside the screen 14, and the electron beam 15 emitted from the electron gun 13 is formed.
Of these, only a predetermined electron beam 15 is selectively passed to cause the phosphor coated on the screen 14 to emit light. First
The shadow mask 18 is supported by the frame 16 and is provided close to the screen 14.

On the other hand, a feature of the present invention is that the second shadow mask 118 is provided inside the first shadow mask 18 while being supported by the frame 16.

A second beam passage hole 22 is formed in the second shadow mask 118 at a position corresponding to the first beam passage hole 21 formed in the first shadow mask 18. The second beam passage hole 22 formed in the second shadow mask 118 is formed larger than the first beam passage hole 21 as shown in FIG.

The second shadow mask 118 is the first shadow mask 18 of the electron beam 15 emitted from the electron gun.
The remaining electron beam 15 excluding the electron beam 15 that passes through the first shadow mask 18 and reaches the screen 14 serves to block the collision with the first shadow mask 18. The size of the second beam passage hole 22 is adjusted so that the second shadow mask 118 does not affect the electron beam 15 passing through the first shadow mask 18 due to thermal expansion due to collision of the electron beam.

The frame 16 has a hook spring 20.
Of the hook spring 20 and the other end of the hook spring 20 is coupled to a stud pin 17 formed on the inner surface of the panel 10.

The cathode ray tube according to the present invention constructed as described above operates as follows to prevent thermal expansion of the first shadow mask 18.

An electron gun 13 arranged in a line on the neck 12.
When three electron beams 15 corresponding to red, green and blue are emitted from the electron beam, the electron beam 15 is deflected by the deflecting device 9 provided outside the funnel 11 and heads for the screen 14.

Electron beam 15 directed to screen 14
First passes through the second beam passage hole 22 formed in the second shadow mask 118. At this time, the electron beam 15 that does not pass through heats the second shadow mask 118. Therefore, the second shadow mask 118 is heated and expanded to cause thermal deformation. However, the second shadow mask 11
The second beam passage hole 22 formed in the first shadow mask 18 is sufficiently larger than the first beam passage hole 21 formed in the first shadow mask 18.
The thermal deformation of 18 does not hinder the path of the effective electron beam 15 passing through the first beam passage hole 21.

Most of the electron beam 15 that has passed through the second beam passage hole 22 passes through the first beam passage hole 21 formed in the first shadow mask 18 to cause the phosphor of the screen 14 to emit light. The electron beam 15 that does not pass through the first beam passage hole 21 heats the first shadow mask 18. However, since the temperature of the first shadow mask 18 heated by the small amount of the electron beam 15 is lower than the temperature of the conventional heated shadow mask, excessive thermal expansion does not occur.

[0027]

In the cathode ray tube of the present invention, since the second shadow mask absorbs most of the remaining electron beam of the electron beam emitted from the electron gun except the effective electron beam, the heat of the first shadow mask is reduced. Expansion can be limited to within a predetermined range. Therefore, it is possible to prevent deterioration of color purity due to mislanding of the electron beam.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a cathode ray tube according to the present invention.

FIG. 2 is an enlarged sectional view showing a main part of a cathode ray tube according to the present invention.

FIG. 3 is a sectional view showing a conventional cathode ray tube.

[Explanation of symbols]

 9 Deflection device 10 Panel 11 Funnel 12 Neck 13 Electron gun 14 Screen 15 Electron beam 16 Frame 17 Stud pin 18 First shadow mask 20 Hook spring 21 First beam passage hole 22 Second beam passage hole 118 Second shadow mask

Claims (2)

[Claims] 1. A panel, a funnel sealed to the panel, an electron gun provided on a neck portion of the funnel to emit an electron beam, and a phosphor provided on the inside of the panel. A screen, a deflector provided outside the funnel for deflecting the electron beam, and a plurality of first beam passage holes provided inside the screen for selectively passing the deflected electron beam. A first shadow mask in which a plurality of second beam passage holes are formed at positions corresponding to the first beam passage holes inside the first shadow mask. A cathode ray tube, further comprising a shadow mask. 2. The cathode ray tube according to claim 1, wherein the size of the second beam passage hole is larger than that of the first beam passage hole.