JP3148393B2 - Cathode ray tube device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a television (T
V) and the like.

[0002]

2. Description of the Related Art FIG.
FIG. 1 is a cross-sectional configuration diagram of a conventional cathode ray tube device disclosed in Japanese Patent Publication No. In the figure, 1 is a face plate panel having a fluorescent screen 2, 3 is a shadow mask provided inside the face plate panel, 4 is a frame supporting the shadow mask, 5 is an electron gun for emitting an electron beam 6, and 7 is An internal magnetic shield arranged around the electron beam, 8
Is joined to the face plate panel 1, and includes a shadow mask 3, a frame 4, an internal magnetic shield 7, and an electron gun 5.
, 9 is a hole in the shadow mask 3, and 10 is a landing point of the electron beam 6.

A conventional cathode ray tube apparatus is constructed as described above. For example, an electron beam 6 emitted from an electron gun 5 strikes a phosphor screen 2 at a landing point 10 of the electron beam 6 through a hole 9 in a shadow mask. And emit a desired color. However, before the electron beam 6 reaches the phosphor screen 2 from the electron gun 5, the orbit is bent by the action of the geomagnetism, and the landing point 10 of the electron beam 6 changes, causing a color shift. Therefore, in JP-A-3-263736, the coercive force when the frame 4, the internal magnetic shield 7, and the shadow mask 3 are each magnetized at 800 A / m is smaller than 90 A / m, and the coercive force of the reinforcing band is applied. When the magnetic field is 800 A / m, it is smaller than 250 A / m.

Japanese Patent Application Laid-Open No. 60-255924 discloses that a magnetic shield member is made to have a relative permeability of about 900 or more even in a low magnetic field such as the terrestrial magnetism by a suitable heat treatment, and is sealed in a cathode ray tube device. I have a shield.

[0005]

In the conventional cathode ray tube device as described above, Japanese Patent Application Laid-Open No. 3-263736 discloses that a coercive force of a frame, an internal magnetic shield and a shadow mask is smaller than 90 A / m and a reinforcing band is used. Has a coercive force smaller than 250 A / m, and shields the terrestrial magnetism acting on the electron beam by the magnetic shielding effect of the frame, the internal magnetic shield, the shadow mask, and the reinforcing band. However, the magnetic shielding effect is governed by the magnetic permeability, and even if the coercive force is small, if the magnetic permeability is not high, the magnetic shielding effect is not sufficient, and there is a problem that color shift due to the action of terrestrial magnetism is not prevented. .

Further, in Japanese Patent Application Laid-Open No. 60-255924, only the magnetic shield member is made to have a relative permeability of about 900 or more even in a low magnetic field such as terrestrial magnetism, and is sealed inside a cathode ray tube device to provide a magnetic shield. . However, the magnetic system
Each of the above members that make up the magnetic field is
The effect of the magnetic shield decreases due to the
Demagnetize before using for the pole tube. Therefore, before demagnetization
The magnetic shielding effect from the magnetic permeability of
Without, color shift due to the action of terrestrial magnetism there is a problem that it is not prevention.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem. Even when terrestrial magnetism acts on a cathode ray tube device, the terrestrial magnetism is shielded by the magnetic shielding effect of a frame, an internal magnetic shield, and a shadow mask. It is an object of the present invention to provide a cathode ray tube device which prevents landing misalignment of a beam and has no color shift.

[0008]

According to the cathode ray tube device of the present invention, the maximum applied magnetic field applied for degaussing is 800 A.
/ M (10 Oe), obtained by a degaussing operation.
The shadow mask has a non-history relative permeability of 4000 or more, the internal magnetic shield has a non-history relative permeability of 8000 or more, and the frame has a non-history relative permeability of 800 or more.

The shadow mask and the inner magnetic shield are made of ultra-low carbon steel having a carbon content of 0.01% or less.

This frame is made of Cr, Mo and Mn.
Carbon steel containing at least one of the following.

[0011]

In the cathode ray tube device constructed as described above, each of the above members constituting the magnetic shield must be demagnetized before use in the cathode ray tube. Therefore, up to 800
When a magnetic field of about A / m (10 Oe) is applied and demagnetized, the magnetic permeability after demagnetization is measured, and this is defined as non-historical relative magnetic permeability.
By setting the non-history relative permeability of the shadow mask to 4000 or more, the non-history relative permeability of the internal magnetic shield to 8000 or more, and the non-history relative permeability of the frame to 800 or more, the shadow mask and the inner part are not affected by geomagnetism. Magnetic shield,
The magnetism of the frame shields geomagnetism.

Further, since the shadow mask and the internal magnetic shield are made of ultra-low carbon steel without using permalloy containing rare and expensive nickel, a stable supply can be received and the cost can be reduced.

Further, since the frame is made of carbon steel containing one or more types of Cr, Mo and Mn, the strength can be maintained without lowering the magnetic permeability.

[0014]

[Embodiment 1] FIG. 1 is a sectional view showing the configuration of a cathode ray tube device according to an embodiment of the present invention.
However, ultra-low carbon steel having a carbon content of 0.01% or less is used for the shadow mask 3 and the internal magnetic shield 7, and the maximum applied magnetic field for degaussing is 800 A / m (10
In the case of about Oe), the non-historical relative magnetic permeability of the shadow mask 3 and the non-hysteretic relative magnetic permeability of the internal magnetic shield 7 obtained by the demagnetizing operation are 10,000 or more. The frame 4 is made of carbon steel containing one or more types of Cr, Mo, and Mn. When the maximum applied magnetic field applied for demagnetization is about 800 A / m, the non-history relative magnetic permeability is 1000 or more.

In the cathode ray tube apparatus constructed as described above, for example, the electron beam 6 emitted from the electron gun 5 passes through the hole 9 of the shadow mask and strikes the fluorescent screen 2 at the landing point 10 of the electron beam, and To emit a color. Even if geomagnetism acts outside the cathode ray tube device before the electron beam 6 reaches the phosphor screen 2 from the electron gun 5, the maximum applied magnetic field applied for demagnetization is 800 A /
m (10 Oe), obtained by demagnetizing operation
The non-historical relative magnetic permeability of the shadow mask 3 is 5,000 or more, and the non-historical relative magnetic permeability of the internal magnetic shield 7 is 10,000.
As described above, since the non-history relative magnetic permeability of the frame 4 is 1000 or more, the shadow mask 3, the internal magnetic shield 7,
The magnetic shielding effect of the frame 4 shields terrestrial magnetism. Therefore, the trajectory of the electron beam 6 hits the phosphor screen 2 at the correct landing point 10 without being bent by the action of terrestrial magnetism, and emits a desired color.

Here, the effect of magnetic shielding by the high magnetic permeability material will be described. References (ALBRECHT J.MAGER "Magn
etic Shields '' IEEE TRANSACTIONS ON MAGNETICS, VOL.
As shown in MAG-6, NO.1, MARCH 1970), in the case of the cylinder illustrated in FIG. 2, the length of the cylinder is infinite, the thickness of the cylinder is d, the radius is D, and the diameter of the cylinder is Assuming that the magnetic permeability is μ, the ratio S = Ho / Hi (magnetic shielding degree) of the strength Ho of the external magnetic field uniform to the axis of the cylinder and the strength Hi of the magnetic field in the cylinder perpendicular to the axis of the cylinder is expressed by the following equation (1). Given by the formula.

[0017]

(Equation 1)

The higher the magnetic permeability, the higher the ratio of the external magnetic field to the internal magnetic field. Since the external magnetic field is constant at the earth magnetism, the higher the magnetic permeability, the higher the magnetic shielding degree and the smaller the internal magnetic field. As described above, in this embodiment, even if terrestrial magnetism acts on the outside of the cathode ray tube device, the applied voltage for demagnetization is the highest.
When the large applied magnetic field is about 800 A / m (10 Oe) ,
Since the non-history relative permeability of the shadow mask 3 obtained by the demagnetizing operation is 5000 or more, the non-history relative permeability of the internal magnetic shield 7 is 10000 or more, and the non-history relative permeability of the frame 4 is 1000 or more. The electron beam 6 emitted from the electron gun 5 hits the fluorescent screen 2 at the correct landing point 10 without receiving the effect of the terrestrial magnetism, and emits a desired color. .

In the present invention, a maximum of 800 A /
A magnetic field of about m (10 Oe) is applied to demagnetize, and the magnetic permeability after demagnetization is measured to obtain a non-historical relative magnetic permeability. The reason why the relative permeability is 8000 or more and the non-historical relative permeability of the frame 4 is 800 or more is that the non-history relative permeability of the internal magnetic shield 7 is 8000 or more.
Is substituted for μ = 8000, and D is set to D = 250 mm as a cathode ray tube device having a plate thickness d = 0.1 mm and a diameter of about 20 inches. When S is determined, S = 4.2 and the magnetic shielding performance becomes sufficient. is there. Μ = 10000 in this embodiment
In the case of, S = 5, which shows a sufficient shielding effect. However, as in the prior art, when μ = about 1000, S = 1.4, and almost no shielding effect can be expected. If the non-history relative magnetic permeability of the internal magnetic shield 7 is 8000 or less, a practically sufficient shielding effect cannot be obtained. The reason why the non-historical relative magnetic permeability of the shadow mask 3 is 4000 or more is a structure in which the internal magnetic shield 7 is covered with a high magnetic permeability material. In this case, a spherical magnetic shield represented by the following equation 2 is used. This is because the same high level of magnetic shielding performance can be obtained, and below this, a practically sufficient shielding effect cannot be obtained.

[0020]

(Equation 2)

Further, the non-historical relative magnetic permeability of the frame 4 which is a joining portion between the shadow mask 3 and the internal magnetic shield 7 is 8
00, the shadow mask 3 represented by Equation 2
Thus, the magnetic shielding performance of the internal magnetic shield 7 can be sufficiently obtained. If it is less than 800, a practically sufficient shielding effect cannot be obtained.

The degree of magnetic shielding is related only to the magnetic permeability and the thickness and radius of the cylinder, as shown in the equation 1, but not to the coercive force. Further, since the magnetic permeability of the internal magnetic shield 7, the frame 4, and the shadow mask 3 is increased so as to surround the trajectory of the electron beam 6 as well as the internal magnetic shield 7, a sufficient magnetic shielding effect can be obtained.

In general, permalloy is used for the high magnetic permeability material. However, since permalloy contains rare nickel and expensive nickel, it is expensive, but in this embodiment, the shadow mask 3 and the internal magnetic shield 7 are used. Since the ultra-low carbon steel having a carbon content of 0.01% or less was used for the demagnetization operation , when the maximum applied magnetic field was about 800 A / m (10 Oe) ,
The resulting, non-history the relative permeability of the shadow mask 5
000 or more, the non-historical relative permeability of the inner magnetic shield is 10
000 or more, high magnetic shielding effect and low cost.

Further, since the frame is made of carbon steel containing one or more types of Cr, Mo and Mn, the strength can be maintained without lowering the magnetic permeability.

[0025]

Since the present invention is configured as described above, it has the following effects.

The maximum applied magnetic field applied for degaussing is 80
0 A / m (10 Oe), obtained by degaussing operation
The non-historical relative permeability of the shadow mask is 4000 or more,
Since the non-historical relative magnetic permeability of the internal magnetic shield is 8000 or more and the non-hysteretic relative magnetic permeability of the frame is 800 or more, even if geomagnetism acts from outside the cathode ray tube device, the shadow mask, the internal magnetic shield, and the magnetic shield of the frame Due to the effect, the earth magnetism is shielded, and the electron beam emitted from the electron gun can hit the phosphor screen at the correct landing point and emit a desired color without being affected by the earth magnetism.

Further, since the shadow mask and the internal magnetic shield are made of ultra-low carbon steel, a stable supply can be obtained without containing rare and expensive nickel. Manufacturing costs can be reduced.

Further, since the frame is made of carbon steel containing one or more types of Cr, Mo and Mn, the strength can be maintained without lowering the magnetic permeability.

[Brief description of the drawings]

FIG. 1 is a cross-sectional configuration diagram showing a cathode ray tube device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating a state of magnetic shielding by a high magnetic permeability material according to the present invention.

FIG. 3 is a cross-sectional configuration diagram showing a conventional cathode ray tube device.

[Explanation of symbols]

 Reference Signs List 1 face plate panel 2 fluorescent screen 3 shadow mask 4 frame 5 electron gun 6 electron beam 7 internal magnetic shield 8 funnel

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01J 29/07 H01J 29/02

Claims (3)

(57) [Claims] 1. A face plate panel having a phosphor screen, a shadow mask provided inside the face plate panel, a frame supporting the shadow mask, and an electron beam emitted from an electron gun. In a cathode ray tube device which is composed of an internal magnetic shield and a funnel joined to the face plate panel and covering the shadow mask, the frame, the internal magnetic shield and the electron gun, the maximum applied magnetic field applied for degaussing is 800 A. in the case of the / m (10Oe), consumption
The non-historical relative permeability of the shadow mask obtained by a magnetic operation is 4000 or more, the non-history relative permeability of the internal magnetic shield is 8000 or more, and the non-history relative permeability of the frame is 800 or more. Cathode ray tube device. 2. The cathode ray tube device according to claim 1, wherein the shadow mask and the internal magnetic shield are made of ultra-low carbon steel having a carbon content of 0.01% or less. 3. The cathode ray tube device according to claim 1, wherein the frame is made of carbon steel containing at least one of Cr, Mo, and Mn.