JP3394794B2 - Cathode assembly - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode assembly used for a color picture tube or the like, and more particularly to a cathode assembly having improved straps and sleeves.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for large-sized color picture tubes for televisions and terminals, high quality and high resolution. Further, also in a projection tube or the like, improvement in brightness is desired. In order to meet such demands for color picture tubes, projection tubes and the like, there has been a demand for higher performance of cathode ray tubes, especially higher current density.

To improve the performance of such a cathode ray tube,
As compared with the oxide cathodes that have been conventionally used, the impregnated type cathodes that can obtain a high current density have attracted attention, and their practical use is being studied in some high-definition televisions and the like. Such an impregnated cathode structure has a cathode sleeve in which a heater is provided, and a cup containing a cathode disk impregnated with an emitter is fitted to one end of the cathode sleeve. The cathode sleeve is a holder arranged coaxially on the outside thereof,
For example, it is fixed by three straps. As a material for this strap, Ta or Nb has been generally used.

[0004]

The impregnated type cathode assembly as described above can be expected to have a high current density, but has an operating density of about 200 ° C. higher than that of an oxide cathode and requires a large amount of heater power. This is an obstacle to practical use. Therefore, in order to save power of the impregnated-type cathode assembly, miniaturization of the cathode assembly has been studied.

Among the miniaturization, it is effective means to reduce the heat conduction loss by reducing the cross-sectional area of the strap to reduce the heat conduction loss. However, since the strap supports the cathode, if Ta or Nb, which has been generally used as a strap material in the past, is made too small, the strap material is deformed due to thermal fatigue during cathode operation, and There is a problem that characteristics such as a deterioration in brightness and a defect in color shift are likely to occur. On the other hand, the strap is Ta-W alloy, Ta-W-Hf alloy, Nb-W alloy,
It has been proposed to use an Nb-W-Hf alloy or the like (see Japanese Patent Laid-Open No. 3-55737), but even when these alloys are used, it is necessary to sufficiently prevent the deformation of the strap. I haven't arrived.

Further, in order to miniaturize the strap, it is also an important condition that the material of the strap is excellent in workability and weldability. However, in these respects, the conventional material is not sufficient and improvement is required. It was wanted.

On the other hand, by making the cathode sleeve itself smaller and thinner, there is a problem that the cathode ray tube characteristics are deteriorated due to thermal fatigue during cathode operation, as in the case of the above-mentioned strap.

From the above, by improving the high temperature strength, workability, weldability, etc. of the strap and the cathode sleeve, the impregnated cathode assembly can be made compact without causing deterioration in brightness or color misregistration. Furthermore, it is strongly desired to achieve power saving. Further, such a request is not limited to the impregnation type cathode, and similarly in the oxide cathode, it is required to improve the high temperature strength, workability, weldability and the like of the strap and the cathode sleeve.

The present invention has been made in order to solve such a problem, and improves the high temperature strength, workability, weldability, etc. of the strap and the cathode sleeve to facilitate the miniaturization of the cathode assembly. Even in the case of miniaturization,
It is an object of the present invention to provide a cathode assembly that prevents deterioration of performance.

[0010]

SUMMARY OF THE INVENTION A cathode assembly according to the present invention comprises a cathode sleeve having a heater therein, a cathode disk fixed to one end of the cathode sleeve, and a predetermined space on the outer peripheral side of the cathode sleeve. And a coaxial holder arranged coaxially and a plurality of straps, one end of which is attached to the lower end of the cathode sleeve and the other end of which is attached to the upper end of the tubular holder. , At least one of the strap and the sleeve is (A) Nb 10 ~
40% by weight, 0.5 to 40% by weight of at least one element selected from V, Re, Ti, Hf, Mo, W and Cr , the balance being substantially
Alloy containing Ta , (B) containing 3 to 40% by weight of at least one element selected from ( V ) V , Re, Ti, Mo and Cr, and leaving the balance.
One part selected from alloys whose parts consist essentially of Ta, or
The (C) W alone, (D) V, Re, Ti, Hf, one or more elements selected from Mo Contact and Cr containing 5 to 50 wt%, the balance being substantially
Characteristically, it consists of one kind selected from the alloys of W.

In the cathode assembly of the present invention, as described above, the strap and the sleeve are made of any one of the A group alloy, the B group alloy, the C group simple metal, and the D group alloy.

Here, the above-mentioned Group A alloy is Ta with Nb.
And an alloy (Ta alloy) to which at least one element selected from V, Re, Ti, Hf, Mo, W and Cr is added. Ta and Nb
Have a solid solution relationship, which improves high-temperature strength and workability, and enhances weldability. In addition, the additional element is
It forms a solid solution in Ta-Nb alloy and has the function of further improving high-temperature strength, workability, and weldability. In Ta alloy
The addition amount of Nb, and the addition amount of the above Kimoto element to Ta alloy are both in the range that can be dissolved, have preferably be in the range of further maintain the high temperature strength. Specifically, the amount of Nb added is 10 to 40.
It shall be the weight percent of the range. The amount of the above elements added to the Ta alloy varies depending on the type of element and the number of added elements, but is 0.
That be in the range of 5 to 40% by weight. Among these group A alloys, Ta-Nb-W, Ta-Nb-Cr and the like are particularly preferable in terms of high temperature strength, workability, weldability and the like.

Further, an alloy of Group B likewise comprises mainly Ta, V a solid solution in Re this, Re, Ti, by adding at least one element selected from Mo and Cr, high-temperature strength , Workability and weldability are improved.
It is also possible to add W or Hf to these alloys for use. The amount of the additional element is preferably limited to an amount that can be dissolved in Ta, varies depending on the kind and the addition element number of elements, in particular shall be the range of 3 to 40 wt%. Among the above additive elements, Ta-V, Ta-Re, Ta-Cr and the like are particularly preferable.

C group single metal (specifically W single metal)
Body) is its Re good high temperature strength alone, workability, which has a welding and the like, can be used as a strap or sleeve of the cathode assembly. However, in terms of further enhancing the high-temperature strength and workability, V, Re, Ti, Hf , Mo you and Cr
It is preferable to use it as an alloy ( W alloy of D group) to which one or more elements selected from the above are added . Similarly alloy of the D Group, we shall combine the elements as composition which forms a solid solution, especially in W -Re, W-Cr, a combination of such W-Cr-Re are preferable. The composition ratio of W alloy is 5 to 50 weight% of the above elements.
It should be added in the range of%. A typical composition ratio is W-5 wt % Re.

The cathode structure of the present invention can be applied to either an impregnated cathode or an oxide cathode, but is particularly suitable for an impregnated cathode.

[0016]

In the cathode structure of the present invention, the alloy or simple metal having excellent high temperature strength and workability as described above,
Since the strap and the sleeve are configured, it is possible to prevent the strap and the sleeve from being deformed due to thermal history even when the cathode structure is miniaturized. Therefore, it is possible to remarkably improve the luminance deterioration defect and the color misregistration defect of the color picture tube and the like, and further reduce the size of the cathode structure to save the power. Further, since the constituent materials of the strap and the sleeve have good workability as well as good weldability, it is possible to easily and reliably manufacture a miniaturized cathode assembly.

[0017]

EXAMPLES Next, examples of the present invention will be described.

FIG. 1 is a sectional view showing an impregnated-type cathode assembly according to an embodiment of the present invention. In the figure, reference numeral 1 is a cathode sleeve, and a heater 2 is provided inside the cathode sleeve 1. This heater 2 is a coiled coil type,
The primary coil 2a is wound more densely than the other parts. In this embodiment, the heater 2 in which the primary coil 2a is wound at a pitch of about 1/3 of the other portion is used.

A cup 3 is fitted in the upper end portion of the cathode sleeve 1, and an emitter-impregnated cathode disk 4 is housed in the cup 3. The cathode disk 4 is, for example, a porous tungsten substrate having a porosity of about 20% impregnated with an emitter material (electron emitting material), and an iridium film is formed on the surface thereof. It should be noted that the cup 3 prevents the heater 2 from being deteriorated in insulation due to scattering of an emitter material, for example, an evaporated material of Ba, from the cathode disk 4 toward the heater 2, and is made of, for example, tantalum.

Further, on the outer peripheral side of the cathode sleeve 1, a shielding cylinder 5 and a cylindrical holder 6 are coaxially arranged in order at a predetermined interval. The cathode sleeve 1 is supported by the cylindrical holder 6 via a plurality of, for example, three strip-shaped straps 7. One end of the strap 7 is attached to the upper end of the tubular holder 6 by welding or the like, and the other end is similarly attached to the lower end of the cathode sleeve 1. The shield tube 5 is supported on the upper end of the tubular holder 6 by a support member, for example, an L-shaped support member 8. The strap 7 is arranged so as not to contact the shielding cylinder 5.

The above-mentioned cathode sleeve 1 and strap 7
Is excellent in high-temperature strength, workability, weldability, etc. (A) TaTo
NbWhenA few selected from V, Re, Ti, Hf, Mo, W, and Cr
At least one element addedTaAlloy, (B) TaTo, V, R
At least one element selected from e, Ti, Mo and Cr
AddedTaAlloy, (C)W alone, Or (D)On W,
V, Re, Ti, Hf,MoAnd selected from Cr1More than a seed
ToW addedIt is made of an alloy. In addition, the cathode
Only one of the leave 1 and the strap 7 is as described above.
It is also possible to compose of special alloys or simple metals.
Use the above-mentioned heat-resistant and high-strength material for the strap 7.
Is effective. In such a case, the cathode sleeve 1 is used.
For that, a Ta product can be used as in the conventional case.

The impregnated cathode structure 9 as described above is used by being incorporated in an electron gun. Specifically, as shown in FIG. 1, a first grid 10 is arranged in front of the impregnated-type cathode assembly 9 with a predetermined gap, and the first grid 10 has a peripheral portion directly made of glass. Insulating support 1
It is buried in 1. A fixing member 12 is attached to the outer peripheral portion of the cylindrical holder 6 of the impregnated cathode assembly 9, and the other end of the fixing member 12 is embedded in the insulating support 11.

The impregnated cathode structure 9 having the above-mentioned structure uses an alloy or a single metal having excellent high-temperature strength, workability, weldability, etc. as a constituent material of the cathode sleeve 1 and the strap 7. It is possible to prevent deformation due to thermal fatigue during operation, which makes it possible to improve defects such as deterioration in brightness and color misregistration of the picture tube.
Further, since the above-mentioned heat-resistant and high-strength material is excellent in workability and weldability, it is easy to downsize the cathode assembly, and even when the cathode sleeve 1 and the strap 7 are downsized, their deformation does not occur. Since this can be prevented, it is possible to achieve power saving of the impregnated-type cathode structure without causing a luminance deterioration defect, a color misregistration defect, or the like of the picture tube.

In the impregnated cathode structure 9 of the above embodiment, the shielding cylinder 5 is arranged between the cathode sleeve 1 and the cylindrical holder 6, and the variable pitch heater is used as the heater 2. Therefore, it is possible to further save power. As a result, the power consumption is about 1/3 of that of the conventional one (2W in the past, but 0.7% in this embodiment).
W) Therefore, in a television receiver using an oxide cathode,
It can be mounted without changing the circuit or the like. As a result of the power saving, the heater temperature is lowered, and thereby the withstand voltage characteristic between the heater 2 and the cathode sleeve 1 is improved (it was 600 V in the forced test in the past, but 1200 V in this embodiment).

In the above embodiment, the impregnated type cathode assembly 9 using the shield cylinder 5 has been described, but the present invention is not limited to this. For example, as shown in FIG. 2, the shield cylinder is omitted. Even when it is applied to the impregnated cathode structure 13, the same effect can be obtained.

Next, a concrete example of the constitution of the impregnated cathode structure shown in FIG. 1 and its evaluation result will be described.

Example 1 First, as constituent materials of the cathode sleeve 1 and the strap 7, alloys and simple metals whose compositions are shown in Tables 1 and 2 were prepared. Then, using the cathode sleeve 1 and the strap 7 using the alloys or simple metals shown in Tables 1 and 2, the impregnated cathode assembly 9 was produced.
The material combinations of the cathode sleeve 1 and the strap 7 are shown in Tables 3 and 4.

[0028]

[Table 1]

[Table 2] The heat resistance (deformation degree) of each impregnated-type cathode assembly whose combination of materials is shown in Tables 3 and 4 was evaluated by measuring the variation value of the cutoff voltage.

Considering the causes of the luminance deterioration defect and the color misregistration defect, the gap (Gg ₁ -k) between the first grid and the cathode (cathode surface) in the design of the electron gun,
Gap between the first grid and the second grid (Gg ₁ -g ₂ ),
Plate thickness of the first clit (Tg ₁ ), hole diameter of the first clyde (Dg
₁ ), using the correction coefficient (K), set the first grid potential to E
When c ₁ and the second grid potential are Ec ₂ , Ec ₁ is regulated by the following equation.

[Equation 1] Also, the cathode current is set to maxIk in the equation: maxIk = K ′ × cos Ec ₁ ^3/2 when the cathode is operating in the space charge region. This maxIk is the beam cutoff voltage when Ec ₁ is maintained at the rated voltage and Ec ₂ (anode voltage) is changed, and is then equal to the anode current when Ec _{1 is set} to zero bias. As can be seen from the above equation, if the size of Gg ₁ -k changes for some reason, the cutoff voltage changes and the anode current changes. When used for a color picture tube, the cutoff voltages of the red, green, and blue electron guns are adjusted so as to develop a predetermined color.
However, when the color picture tube is used for a long time, the constituent material of the cathode assembly is deformed due to thermal fatigue, and the dimensional change of Gg ₁ -k occurs. Since this deformation is not constant in each electron gun of red, green, and blue, the anode current incident on the phosphor screen changes, causing color shift and luminance deterioration.

As described above, since the dimensional deformation between the cathode and the first grid is proportional to the change amount of the cutoff voltage,
By measuring the amount of change in the cutoff voltage, the degree of deformation of the strap can be evaluated relatively accurately.

Then, a heating and cooling test was conducted using each impregnated cathode assembly according to the above-mentioned example, and the variation of the cutoff voltage was measured. The condition at that time is 5 minutes on + 10 minutes off,
This was repeated at a cathode temperature of 1150 ° C. The variation values of the cutoff voltage after repeating such on / off 4000 times are also shown in Tables 3 and 4. 3 and 4 show typical examples of the relationship between the number of times ON / OFF is repeated and the variation value of the cutoff voltage. Since the change was slow at normal operating temperature, the cathode assembly was forcibly heated to 1150 ° C., and after it became stable, cooling was repeated to examine the variation value of the cutoff voltage.

Further, regarding the workability of the alloys and simple metals shown in Tables 1 and 2, a sample of 50 × 50 × 20 mm was prepared and heated at 1000 ° C. for 5 hours, and then taken out.
It was pressed to a thickness of 10 mm with a 0 ton hydraulic press and the state of side cracks was evaluated. Also, make a thin plate with a thickness of 0.5 mm,
Laser welding is performed by stacking two sheets (one is Ta), heating in vacuum at 1000 ° C for 30 minutes, and then rapidly cooling.
By repeating 20 times and checking for peeling,
Weldability was evaluated. These results are also shown in Tables 3 and 4.

[0033]

[Table 3]

[Table 4] As can be seen from Tables 3 and 4, the impregnated cathode structure using the strap or the cathode sleeve according to the present invention has a small change in cutoff voltage, and thus can significantly improve the luminance deterioration defect, the color misregistration defect, and the like. . Further, it can be seen that the alloys and simple metals used as the constituent materials of the strap and the cathode sleeve in the present invention are excellent in workability and weldability, which is advantageous for downsizing the cathode structure.

From FIGS. 3 and 4 , the impregnated cathode structure using the conventional material begins to show a change when the number of on / off repetitions is small, whereas the impregnated cathode structure according to the present invention. In, it can be seen that even if it is repeatedly turned on and off for a long time, there is almost no change, and stability is excellent.

Next, the present invention is explain about the embodiment applied to the oxide cathode structure.

The oxide cathode structure according to embodiments of this includes a cathode sleeve cathode disc (cathode base metal) is press-fitted welded. The cathode sleeves, for example generally nichrome tube which is commercially available (20wt% Cr-Ni) and strengthened nickel - consists of chromium material (4wt% W-20wt% Cr -Ni) or the like, the oxide film on the surface Has been formed. Cathode sleeves is therefore to scan <br/> trap, and is supported by the coaxially arranged cylindrical Hol da on the outer peripheral side thereof.

[0037] The strap, as in the embodiment described above, constituted by an alloy or a single metal according to the invention (A group of alloys, an alloy of Group B, a single metal of group C or D group alloy) It is a thing.
Inside the cathode sleeves, heater data is provided.

Thus, even in the oxide cathode assembly,
By improving the high temperature strength of the strap material, it is possible to remarkably improve the luminance deterioration defect and the color misregistration defect.

[0039]

As described above, according to the cathode assembly of the present invention, the high temperature strength, workability, weldability and the like of the strap and the cathode sleeve are improved. It is possible to remarkably improve the luminance deterioration defect and the color misregistration defect. Further, it is easy to reduce the size of the cathode structure, and even when the size is reduced, it is possible to suppress the deterioration of the characteristics of the picture tube, so that it is possible to save power while maintaining high performance.

[Brief description of drawings]

FIG. 1 is a sectional view showing a structure of an impregnated-type cathode assembly according to an embodiment of the present invention.

FIG. 2 is a sectional view showing the structure of another impregnated-type cathode assembly according to the present invention.

FIG. 3 is a graph showing an example of a relationship between the number of times the on / off cycle of the impregnated cathode structure according to the embodiment of the present invention is repeated and the change in cutoff voltage .

FIG. 4 is a graph showing another example of the relationship between the number of times ON / OFF is repeated and the change in cutoff voltage of the impregnated-type cathode assembly according to the embodiment of the present invention .

[Explanation of symbols]

1 ... Cathode sleeve 2 ... heater 3 ... cup 4 ... Cathode disk 5: Cylindrical holder 6 ... Strap

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiharu Higuchi 72 Horikawa-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Toshiba Corporation Horikawa-machi factory (72) Toru Yabei 72 Horikawa-cho, Sai-ku, Kawasaki-shi, Kanagawa Toshiba Corporation (56) Reference JP-A-64-10539 (JP, A) JP-A-63-146322 (JP, A) JP-A-62-108422 (JP, A) JP-A-2-121235 (JP , A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01J 1/20

Claims (2)

(57) [Claims] 1. A cathode sleeve in which a heater is provided, a cathode disk fixed to one end of the cathode sleeve, and a tubular shape coaxially arranged on the outer peripheral side of the cathode sleeve with a predetermined gap. In a cathode structure comprising a holder and a plurality of straps, one end of which is attached to a lower end portion of the cathode sleeve, and the other end of which is attached to an upper end portion of the tubular holder, at least one of the strap and the sleeve is (A) 10-40% by weight of Nb, V, Re, Ti, Hf, Mo, W and
0.5-40% by weight of at least one element selected from Cr
However, the balance is an alloy consisting essentially of Ta , and (B) at least 1 selected from V , Re, Ti, Mo and Cr.
Contains 3 to 40% by weight of the seed element , the balance being essentially Ta.
Alloy or we selected cathode assembly characterized by comprising the one member that. 2. A cathode sleeve in which a heater is installed, a cathode disk fixed to one end of the cathode sleeve, and a tubular shape coaxially arranged on the outer peripheral side of the cathode sleeve with a predetermined gap. In a cathode structure comprising a holder and a plurality of straps, one end of which is attached to a lower end portion of the cathode sleeve, and the other end of which is attached to an upper end portion of the tubular holder, at least one of the strap and the sleeve is (C) a simple substance of W, and (D) an alloy containing 5 to 50% by weight of one or more elements selected from V, Re, Ti, Hf, Mo and Cr, and the balance being substantially W. Cathode structure characterized by consisting of only one type.