JPH0749724Y2 - Electron gun for color CRT - Google Patents

Description

[Detailed description of the device]

 [Purpose of device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron gun for an in-line color cathode ray tube, and more particularly to an electron gun for a color cathode ray tube in which the influence of heat or mechanical shock on the cathode is reduced to reduce the change in cathode current. ..

[0002]

2. Description of the Related Art In general, a color cathode ray tube has, as shown in FIG. 3, an envelope composed of a panel 1 and a funnel 2 integrally joined to the panel 1, and an inner surface of the panel 1 has a three-color fluorescent light. A phosphor screen 3 composed of a body layer is formed, and a shadow mask 4 having a large number of electron beam passage holes formed therein is disposed so as to face the phosphor screen 3. An electron gun 7 that emits three electron beams 6B, 6G, and 6R is arranged in the neck 5 of the funnel 2. And three electron beams emitted from this electron gun 7
6B, 6G, 6R are deflected by the magnetic field generated by the deflection yoke 8 mounted on the outer side of the funnel 2, and the phosphor screen 3 is horizontally and vertically scanned to display a color image on the phosphor screen 3. It is formed in a display structure.

In such a color cathode ray tube, an in-line type electron which emits three electron beams 6B, 6G and 6R arranged in a row, which is composed of a center beam 6G passing through the electron gun 7 on the same plane and a pair of side beams 6B and 6R. There is a gun.

This in-line type electron gun 7 usually has three cathodes arranged in a line on the same plane, three heaters for heating the cathodes separately, and controls and emits electrons from the cathodes. It is composed of a plurality of electrodes such as an electrode for accelerating and focusing the generated electrons to form an electron beam and an electrode for accelerating and focusing the electron beam toward the phosphor screen 3.

4 and 5 show the structure in the vicinity of the cathode of the in-line type electron gun. In this electron gun, the three cathodes KB, KG, KR (only the central cathode KG is shown) arranged in a row are connected to the cathodes KB, KG, KR via the cathode supports 10B, 10G.10R, respectively. It is integrally fixed by a pair of insulating supports 11 together with other heaters such as the first and second grids G1 and G2 which are sequentially adjacent to the three heaters H and the cathodes KB, KG and KR which are separately heated.

The above-mentioned cathode supports 10B, 10G.10R are cylinders 12 that individually surround and support the cathodes KB, KG, KR.
And straps welded to the cylinder 12
13B, 13G, 13R and their respective straps 13B, 13G, 13
The tip of R is fixed to the pair of insulating supports 11. The shape of the straps 13B, 13G, 13R is the central cathode KG.
And the cathodes KB and KR on both sides are different, and the cathode KG in the center is different.
The strap 13B of the cathode support 10G that supports the cathode support 10G has flat plate-shaped parts at both ends of the arc surrounding the cylinder 12, but the straps 13B of the cathode support 10B and 10R that support the cathodes KB and KR on both sides. The straps 13B and 13R are provided with bent plate-like portions 17b at both ends of an arc portion surrounding the cylinder 12.

By the way, generally, when a color cathode ray tube is incorporated in a television set, the cathode current is controlled by appropriately setting a cutoff voltage, a drive voltage and the like in order to optimally adjust the brightness and the color tone. However, since this cathode current is affected by the distance between the cathodes KB, KG, KR and the first and second grids G1, G2,
Usually, after the heater H is ignited, it is performed when they reach a thermal equilibrium state and become stable. Therefore, the cathode current changes after the heater H is ignited until the cathodes KB, KG, KR and the first and second grids G1, G2 become thermally stable, and accordingly, the brightness and color tone on the phosphor screen 3 are changed. Changes.

In order to reduce the change in the cathode current after the heater H is ignited and until it is thermally stabilized, the cathode supports 10B, 10G.10R and the first and second grids G1, G2 are conventionally different.
Is formed of a low thermal expansion material, but when the cathode support 10B, 10G.10R is formed of a low thermal expansion material in this way, the temperature reached and the amount of thermal change of the cathode support 10B, 10G.10R are
And a strap whose both ends are fixed to the pair of insulating supports 11 because it is larger than that of the second grids G1 and G2.
Cylinder 14 is compressed by the thermal expansion of 13B, 13B, 13R to make it easily deformed.

In the normal operating state of the color cathode ray tube, this action does not reach the point where the cylinder 12 is deformed. However, when an impact is applied to the color cathode ray tube in this heating state, the impact causes the neck 5 and its end portion. It is transmitted to the pair of insulating supports 11 through the sealed stem, the stem pin that hermetically penetrates the stem, the stem lug welded to the stem pin, and the like. As a result, as shown in FIG. 5, the pair of insulating supports 11 are connected to the cathode supports 10B, 10G.10R,
Compressive force and tensile force indicated by arrow 15 are applied to the first and second grids G1, G2, etc. The compressive force and the tensile force have a great influence on the structure, especially on each cathode support 10B, 10G.10R.

By the way, the cathode supports 10B, 10G.
The strength of the 10R straps 13B, 13B, 13R in the direction of impact is the sum of the strength of the strap 13B supporting the central cathode KG and the strength of the straps 13B, 13R supporting KB, KR on both sides. Of the three straps 13B, 13B, 13R that are almost equal in strength to one grid G1, the strap 13B supporting the central cathode KG has three flat straps 13B, 13B because the plate portion is flat. , 13R occupies more than 60% of the total strength, and the straps 13B and 13R that support the cathodes KB and KR on both sides are bent, so
Each is less than 20% of the total strength. Therefore, a relatively large impact force is applied to the cylinder 12 supporting the central cathode KG integrally with the strap 13B, and the cylinder 12 is deformed to a large extent, but the cathodes KB and K on both sides are deformed.
The cylinder 12 supporting the R has a folded strap 13
The impact force applied by the buffering action of B and 13R is relatively small, and the degree of deformation is small.

Therefore, as described above, each cathode KB, KG,
When the degree of deformation of the cylinder 12 that supports KR is different, the distance between each cathode KB, KG, KR and the first grid G1 changes according to the size, and the cathode current of the central cathode KG is greatly reduced. However, the brightness on the phosphor screen 3 decreases, and the color tone changes accordingly. For example, if the central cathode KG is for green and the cathodes KB and KR on both sides are for blue and red respectively, this change in color tone may cause a white screen to momentarily appear at the time of impact due to the decrease in green brightness. Turns purple.

[0012]

As described above, in order to reduce the change in the cathode current after the heater is ignited as compared with the prior art, the cathode support including the cylinder and the strap for supporting the cathode and the first and second grids are provided. There is an electron gun formed of a low thermal expansion material. However, in this electron gun, since the temperature reached by the cathode support and the amount of change in heat are larger than those of the first and second grids, thermal expansion of the heated strap makes the cylinder easily deformable. Therefore, when a shock is applied in this state, the cylinder is deformed, and the cathode current is changed by the change in the distance between the cathode and the first grid. Moreover, in the electron gun for an in-line type color cathode-ray tube, the strength of the strap supporting the central cathode is larger than the strength of the strap supporting the cathodes on both sides, so a relatively large impact force is applied to the cylinder supporting the central cathode. Are added directly, causing this cylinder to deform more than the cylinder supporting the cathodes on both sides. As a result, there is a problem that the brightness and color tone on the phosphor screen are changed.

The present invention has been made in order to solve the above problems, and in an electron gun for an in-line type color cathode ray tube, a cathode supporting a cathode is supported by an impact applied when the support is in a heated state. Among the deformations of the cylinder, especially the deformation of the cylinder that supports the central cathode is reduced to reduce the change in the cathode current and to reduce the brightness and change the color tone on the phosphor screen caused by the shock applied when the heating state is applied. The purpose is to construct an electron gun for color cathode ray tubes that reduces the

[Constitution of device]

[0015]

Each of the cathodes has three cathodes arranged in a line on the same plane, heaters for heating the cathodes, and first and second grids sequentially arranged on the cathodes. An electron for a color cathode ray tube, which is fixed to a pair of insulating supports together with the heater and the first and second grids through a cathode support composed of a cylinder supporting each cathode separately and a strap attached to the cylinder. In the gun, among the three cathodes arranged in a row, at least one of the width and plate thickness of the cathode support strap that supports the central cathode is set to the width and plate thickness of the cathode support straps that support the cathodes on both sides. Of at least one of the cathode supports for supporting the central cathode. The coefficient of thermal expansion of the strap of the body is made equal to the coefficient of thermal expansion of the first and second grids, and supports the cathodes on both sides with respect to the coefficient of thermal expansion of the strap of the cathode support that supports the cathode in the center. The coefficient of thermal expansion of the cathode support strap was increased.

[0016]

As described above, at least one of the width and the plate thickness of the strap of the cathode support that supports the central cathode is smaller than the width and the thickness of the strap of the cathode support that supports the cathodes on both sides. Then, when a shock is applied to the electron gun, the shock applied to the strap supporting the central cathode is made relatively small, while the shock applied to the straps supporting the cathodes on both sides is made relatively large, and The deformation of the cylinder that supports the cathodes on both sides can be reduced, and the deformation of the cylinder that supports the cathodes on both sides can be increased to make the deformation amounts of the cylinders that support the cathodes on the center and both sides almost equal. It is possible to make the changes in the cathode current of the above-mentioned approximately equal.

However, in this case, as described above, at least one of the width and plate thickness of the strap of the cathode support that supports the central cathode is set to at least one of the width and plate thickness of the strap of the cathode support that supports the cathodes on both sides. If it is smaller than this, the heat capacity of the strap that supports the central cathode decreases, and the reached temperature and the amount of heat change of this strap after the heater is ignited increase, and the change state of the cathode current between the center cathode and the cathodes on both sides Will be different. However, the coefficient of thermal expansion of the strap supporting the central cathode is made equal to the coefficient of thermal expansion of the first and second grids, and smaller than the coefficient of thermal expansion of the straps supporting the cathodes on both sides, and the thermal change of this strap is changed. By increasing the amount and making it approximately equal to the amount of thermal change of the strap supporting the central cathode, the changing state of the cathode current can be made substantially the same.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments with reference to the drawings.

FIG. 2 shows an in-line type electron gun which is one of the embodiments. This electron gun has three cathodes KB, KG, KR (only KG shown) arranged in a line on the same plane, three heaters (not shown) for heating these cathodes KB, KG, KR separately, and the above-mentioned cathode KB. , KG, KR, the first to sixth grids G1 to G6 and the convergence cup C attached to the sixth grid G6. The cathodes KB, KG, KR, the heater, and the first to sixth grids G1 to G6 are integrally fixed by the pair of insulating supports 11.
Especially for the cathodes KB, KG, KR, the cathode support 20B,
It is fixed via 20G and 20R (only 20G is shown).

The cathode supports 20B, 20G and 20R are shown in FIG.
As shown in Fig. 2, each of them comprises a cylinder 21 surrounding and supporting each cathode separately, and strip-shaped straps 22B, 22G, 22R welded to each cylinder 21, and each strap 22B, 22G, 22R has a pair of insulating supports 11
It is fixed by. The strap 22B, 22G, 22R
For the strap 22G supporting the cathode KG in the center, flat plate parts are provided at both ends of the circular arc surrounding the cylinder 21, but the cathodes KB, K at both ends are
The straps 22B and 22R that support R are provided with bent plate-shaped portions at both ends of an arc portion surrounding the cylinder 21.

Moreover, in the electron gun of this example, the width and plate thickness of the strap 22G supporting the central cathode KG are formed smaller than the width and plate thickness of the straps 22B, 22R supporting the cathodes KB, KR at both ends. , Its central cathode KG
The strength of the strap 22G supporting the cathode KB, K at both ends
It is 45 to 50% of the strength of the straps 22B and 22R that support R. Furthermore, in the electron gun of this example, the central cathode
The strap 22G supporting the KG has the first and second thermal expansion coefficients.
It is made of a material with the same coefficient of thermal expansion as the grids G1, G2. And a strap that supports this central cathode KG
For 22G, the straps 22B and 22R supporting the cathodes KB and KR at both ends are made of a material having a larger coefficient of thermal expansion.

By the way, as described above, the central cathode KG
If the width and plate thickness of the strap 22G supporting the electron guns is made smaller than the width and plate thickness of the straps 22B, 22R supporting the cathodes KB, KR on both sides, if an impact is applied to the electron gun,
The impact applied to the strap 22G supporting the central cathode KG is relatively small, while the impact applied to the straps 22B and 22R supporting the cathodes KB and KR on both sides is relatively large, and the central cathode KG is supported. The deformation of the cylinder 21 that supports the cathodes KB and KR on both sides is increased and the deformation of the cylinder 21 that supports the cathodes KG, KB and KR on both sides is made approximately equal. be able to. Therefore, it is possible to make the changes in the cathode currents of the cathodes KG, KB, KR on the center and both sides substantially equal.

However, in this case, if the width and plate thickness of the strap 22G supporting the central cathode KG is made smaller than the width and plate thickness of the straps 22B, 22R supporting the cathodes KB, KR on both sides as described above, The heat capacity of the strap 22G supporting the cathode KG of the above is decreased, and the reached temperature and the amount of change in heat of the strap 22G supporting the cathode KG in the center after the heater ignition is increased, and the cathode KB in the center and the cathodes KG, KR on both sides are increased. And the change state of the cathode current becomes different. But the strap that supports the central cathode KG
If the coefficient of thermal expansion of 22G is made equal to the coefficient of thermal expansion of the first and second grids G1, G2, and is smaller than the coefficient of thermal expansion of the straps 22B, 22R supporting the cathodes KB, KR on both sides, the cathodes KB on both sides, The straps 22B and 22R that support KR have an increased amount of heat change, and the strap 22G that supports the central cathode KG.
Can be made approximately equal to the amount of change in heat. Therefore, by combining the width and thickness of the straps 22B, 22G, 22R and the coefficient of thermal expansion of the straps 22B, 22G, 22R,
The change state of the cathode current can be the same, and it is possible to reduce the decrease in the screen brightness and the change in the color tone that occur when the cathodes KB, KG, and KR that are conventionally heated are impacted.

In the above embodiment, the width and plate thickness of the strap of the cathode support which supports the central cathode are made smaller than the width and plate thickness of the strap of the cathode support which supports the cathodes on both sides. The width and the plate thickness of the strap may be changed by changing either the width or the plate thickness.

[0025]

EFFECT OF THE INVENTION Of three cathodes arranged in a line on the same plane, at least one of the width and the plate thickness of the strap of the cathode support that supports the central cathode supports the cathodes on both sides. If the strap is made smaller than at least one of width and thickness, the impact applied to the strap supporting the central cathode is relatively small when the electron gun is impacted, and conversely to the strap supporting both cathodes. The impact applied is relatively large to reduce the deformation of the cylinder that supports the central cathode, and the deformation of the cylinder that supports the cathodes on both sides is large, and the amount of deformation of the cylinder that supports the cathodes on the center and both sides. Can be almost equalized, and the changes in the cathode current of the cathodes on the center and both sides can be made almost equal. It can be. Moreover, in this case, the coefficient of thermal expansion of the strap supporting the central cathode is set to
If the coefficient of thermal expansion of the strap that supports the cathodes on both sides is made larger than the coefficient of thermal expansion of the strap that supports the cathode in the center and is equal to the coefficient of thermal expansion of the grid, By increasing the amount of change and making it approximately equal to the amount of heat change of the strap supporting the central cathode, the changing state of the cathode current can be made the same, thereby supporting the central cathode as described above. By making at least one of the width and the thickness of the strap smaller than at least one of the width and the thickness of the strap that supports the cathodes on both sides, it is possible to make the change state of the cathode current of the cathodes on the center and both sides substantially the same. It is possible to reduce the brightness and change the color tone of the screen that occurs when an impact is applied to the conventionally heated cathode. The can be effectively reduced.

[Brief description of drawings]

FIG. 1 is a view showing a cathode support structure of an in-line type electron gun which is an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of an example electron gun of the embodiment.

FIG. 3 is a diagram showing a configuration of a color CRT.

FIG. 4 is a diagram showing a structure near a cathode of the conventional electron gun.

FIG. 5 is a view showing a cathode support structure of the electron gun.

[Explanation of symbols]

 11 ... Insulating support 20B, 20G, 20R ... Cathode support 21 ... Cylinder 22B, 22G, 22R ... Strap G1 ... First grid G2 ... Second grid KG ... Cathode

Claims (1)

[Scope of utility model registration request] 1. A cathode having three cathodes arranged in a line on the same plane, a heater for heating the cathodes, and first and second grids sequentially arranged on the cathodes, each of the cathodes including the cathodes. An electron gun for a color cathode-ray tube fixed to a pair of insulating supports together with the heater and the first and second grids through a cathode support consisting of a cylinder supported separately and a strap attached to the cylinder. Of the three cathodes arranged in a row, at least one of the width and plate thickness of the strap of the cathode support that supports the central cathode is at least one of the width and plate thickness of the strap of the cathode support that supports the cathodes on both sides. And a strap for the cathode support that also supports the central cathode above And a cathode support that supports the cathodes on both sides with respect to the coefficient of thermal expansion of the strap of the cathode support that supports the central cathode. An electron gun for color cathode ray tubes characterized by having a large coefficient of thermal expansion of the strap.