JPH03210736A - Electron gun for cathode-ray tube - Google Patents

Abstract

PURPOSE:To obtain a good white color balance at the time of image output by manufacturing a cathode support for a center and cathode supports for both sides out of Fe-Ni alloys slightly different in Ni content. CONSTITUTION:Each cathode support is manufactured out of Fe-Ni alloys containing 35-50% of Ni. At that time, the Ni content difference giving the maximum difference of thermal expansion coefficient is max + or -8% and therefore the Ni content difference among the Fe-Ni alloys for manufacturing the cathode support for the center 4b and cathode supports for both sides 4a, 4c should be set within the max + or -. Owing to thermal expansion, a G1 electrode is face- deformed toward a G2 electrode and the quantity is several mum and as shown in the figuar, the quantity of the thermal expansion of the support 4b in Z direction is slightly large as compared with that of the supports 4a, 4c. As a result, the gap between the support 4b and the G1 electrode and the gap between the supports 4a, 4c and the G1 electrode do not change and rising up of current of B and RG becomes almost the same and thus white balance becomes good.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention provides R (red), G (green),
Regarding in-line electron guns that produce B (blue) electron beams, we especially recommend electron guns for cathode ray tubes that have good white balance after the heater in the cathode is turned on, that is, R, G electron beams.
This invention relates to an electron gun for a cathode ray tube equipped with a cathode holding structure such that the rise of the currents of B and B are almost the same.

[Conventional technology]

FIG. 7 is a configuration diagram schematically showing the main parts of an electron gun for a cathode ray tube, in which (la), (lb), and (lc) are heaters arranged in parallel on the same plane; ,
(2b).

(2c) can be set to a predetermined temperature (approximately 800° C. during operation). These cathodes (2a).

(2b), (2c) are respectively cylindrical eyelets (also called metal cylinders) (3a), (3b), (3c)
is held in place within the Further, the eyelets (3a), (3b), (3c) are held and fixed by the cathode supports (4a), (4b), (4c), and the cathode sabot t-(4a).

(4b), (4c), Gl electrode (5), G2 electrode (6
), G3 electrode (7), and G4 electrode (8) are held and fixed by bead glass (9), which is an insulating support.

In this way, a series of assemblies held and fixed to the bead glass (9) are welded and supported by a stem (not shown), thereby constructing an electron gun.

In addition, the above cathode supports (4a), (4b),
Specifically, (4c) has a shape like the perspective view shown in FIG. 8, and (10a), (fob), (I
nc) is a portion to which the compressive thermal stress (in the direction of the arrow) from the bead glass (9) is applied, and is shown in the form of hatching (10d).

The same compressive thermal stress (in the direction of the arrow) as above is also applied to (10e) and (10f). The site cathode supports (4a), (4c) and the center power sword sabot 1-(4b) are both made of the same material or a material having an equivalent coefficient of thermal expansion, preferably with Ik rise characteristics. (White balance rise characteristics)
Above, low expansion materials are suitable.

Next, the operation of the above configuration will be explained.

First, based on FIG. 7, the cathode (2a
), (2b), (2c), the electrons emitted from Gl
After being controlled by the electrode (5), the electrons are accelerated by the G2 electrode (6) and focused by the main electron lens (not shown) arranged between the 63rd electrode (7) and the 64th electrode (8). The book becomes an electron beam. At this time, the heater (la),
Due to the heat generation of (lb) and (Ic), the cathode (2a)
, (2b), (2c) are heated to at least about 720°C, and the eyelets (3a), (3b), (3
c) is heated to at least about 400<0>C, and the cathode supports (4a), (4b), (4c) are also heated to at least 200-300<0>C. Due to such a temperature increase, parts such as the cathode, eyelet, and cathode support, which are usually made of metal materials, naturally become damaged.
Causes thermal expansion. Also, heaters (lx), (lb),
The cathode supports (4), (4b), (4c) and the Gl electrode (5), which are located close to (Ic) and have a relatively high temperature, have large heat capacities and are heat sources such as heaters (Ia), ( Since there is a bead glass (9) fixed by a relatively low-temperature 63 electrode +7), a G4 electrode (8) and a stem (not shown) located at a distance from lb) and (lc), the above bead glass (9) is subjected to compressive thermal stress.

The above cathode supports (4L), (4b), (4
c) as shown in Figure 8, each has the same shape and is independent from the other, so the center cathode support (4b)
As is clear from the state after thermal expansion shown by dotted lines 4A, 4B, and 4C in Figure 10, the cathode supports (4a) and (4c) for both sides have almost the same amount of thermal expansion in the Z direction. The Gl electrode (5) is also a common component for R, G, and B, and since these R, G, and B are not symmetrical,
As shown by the dotted line 5A, out-of-plane deformation occurs. Although this amount of out-of-plane deformation is only a few μm, the distance between the G1 electrode (5) and the cathodes (21), (2b), and
1-), when the heater is off, that is, when the heater is not generating heat, each cathode is connected to Gl for each of R, G, and B.
- If the interval is set to be the same size, the heater O
In the heat generation state of N, the gap between Gl- of G at the center is several μF wider than the gap between Gl- of R and B on both sides, and as a result, the cutoff voltage of G becomes high. Note that since the distal end surface of the cathode and the distal end surface of the cathode support are substantially on the same plane, throughout this specification, the distance between the Gl- and G1 electrodes refers to the distance between the G1 electrode and the cathode, and the distance between the Gl electrode and the cathode support. For convenience, the intervals of G1 and GIK are treated as the same.
shall mean the spacing between the electrode and the cathode support.

Therefore, until now, before the heater heats up, the above-mentioned number of μ-
By correcting only the amount, the interval is changed to Gl- of G, G of B
By setting l- narrower than the interval, R, G
, B had the same cutoff voltage. That is, by setting in advance the gap between Gl- of G and the Gl- of R and B before the heater heats up, by several micrometers narrower than the gap between R and B, when the heater heats up, R
The intervals between IG and Gl- of B were made to be the same as a result.

[Problems to be Solved by the Invention] However, even if the above-mentioned means are adopted, during the time when the heater generates heat, that is, during the operation of the electron gun, until the thermal equilibrium state is reached, as shown in FIG. As a result, the current of G becomes larger than the current of R9B, and a white balance problem occurs in which the screen chromaticity becomes stronger in G (green) than in the setting.

This invention was made in view of the above-mentioned problems, and the interval built-in value is set to R, G, Gl- when the heater is not generating heat.
It is an object of the present invention to provide an electron gun for a cathode ray tube, which can make the cutoff voltage the same for R, G, and B, and has good white balance characteristics when outputting an image on a screen.

[Means to solve the problem]

In order to achieve the above object, the present invention provides G1 to G
4 electrodes, a plurality of cathodes provided close to the Gl electrode 17, a plurality of eyelets that hold each of the cathodes, and a plurality of cathode supports that weld and fix each of the eyelets to the bead glass. In a cathode ray tube electron gun, each of the above cathode supports is N! It is made of a Fe-Ni alloy with a content of 35 to 50%, and each cathode support thermally expands with the out-of-plane deformation of the Gl electrode, so that the distance between the Gl electrode and each cathode support changes before and after the operation of the electron gun. Ni in the Fe-Ni alloy is removed between the center cathode support and both side cathode supports that make up the cathode support so as not to change in the Fe-Ni alloy.
The content rates were set differently so that the content rate difference was within a maximum range of 8%.

[Effect]

According to this invention, the cathode supports constituting the electron gun are formed of a Fe-Ni alloy with an N4 content of 35% to 50%, and each cathode support thermally expands with the out-of-plane deformation of the G1 electrode. In order that the distance between the Gl electrode and each cathode support does not change before and after the operation of the electron gun, the center cathode support that constitutes the cathode support and the Fe-
Since the Ni content in the Ni alloy was set to differ by a maximum of 8% difference between the two types, the Gl electrode deforms out of plane toward the 62 electrode side during electron gun operation. For the electron gun, by increasing the Ni content in the Fe-Ni alloy of the center cathode support by up to 8% compared to the cathode supports for both sides, the center cathode support is The amount of thermal expansion deformation increases, and as a result, the cathode support as a whole deforms by the same amount in the same direction as each part of the Gl electrode.

In addition, for an electron gun in which the G1 electrode is deformed out of plane toward the cathode support side, the Ni content in the Fe-Ni alloy of the cathode supports for both sides should be increased by up to 8% compared to the cathode support for the center. As a result, the amount of thermal expansion and deformation of the cathode supports for both sides is larger than that of the center cathode support, and as a result, the cathode support as a whole deforms by the same amount in the same direction as each part of the Gtl electrode. I will do it.

As described above, according to the present invention, even when the Gl electrode is deformed out of plane to either the 62 electrode side or the cathode side, the center cathode support or the both side cathode supports deform the G1 electrode out of plane. The distance between the Gl electrode and each cathode support does not substantially change before and after operation of the electron gun, and the Rl before and after operation of the electron gun, that is, before and after heat generation by the heater,
As a result, the intervals between Gl- of G and B are the same. Therefore, the cut-off voltage is also the same for R, G, and B, and the interval built-in value for Gl- before the heater heats up can be made the same for RlG and B, and the white balance characteristics at the time of screen image output are improved.

[Embodiments of the invention]

An embodiment of the present invention will be described below.

FIG. 1 is a configuration diagram schematically showing the state of thermal deformation in the Z direction in the cathode holding structure portion of an electron gun according to a first embodiment of the present invention, and FIG. 2 is a diagram showing a cathode of an electron gun according to a second embodiment of the present invention. FIG. 3 is a configuration diagram schematically showing a state of thermal deformation in the Z direction in a holding structure portion.

In the drawing, (5) is a Gl electrode, and (4a).

(4C) is a side cathode support, and (4b) is a center cathode support.

In the cathode holding structure of an electron gun having such a configuration, the first embodiment shown in FIG. 1 shows a type in which the G1 electrode is deformed out of plane toward the G2 electrode (not shown), and compared to the both-side cathode support. Therefore, the Ni content in the Fe-Ni alloy constituting the center cathode support was increased to within 8% at maximum.

As a specific example, when forming a cathode support with a 47-50% Fe-Ni alloy, for example, a 50% FeNi alloy is used for the center cathode support, and a 50% FeNi alloy is used for the cathode supports for both sides. Fe-
A 47% Ni alloy is used.

In addition, when forming the cathode support with Fe-Ni 35-38% alloy, use Fe-Ni 35% alloy as the constituent material of both side cathode supports, and use Fe-Ni38% as the constituent material of the center cathode support. %
Use alloy.

On the other hand, the second embodiment shown in FIG. 2 shows a type in which the Gl electrode is deformed out of plane toward the cathode support side, and compared to the center cathode support, the Fe-Ni alloy constituting the both side cathode supports is Ni content up to 8
Increased within %.

In addition, in a specific example of the second embodiment, the Ni content of the Fe-Ni alloy used in the center cathode support and the cathode supports for both sides in the first embodiment may be reversed.

As described above, the reason why Fe--Ni alloy is used as a component of the cathode support in the first and second embodiments is that this Fe--Ni alloy is a low expansion material. As is clear from the graph of FIG. 6, the relationship between the temperature and the coefficient of thermal expansion of the Fe--Ni alloy changes as the Ni content increases or decreases, but it is also strongly influenced by the temperature itself.

In addition, as shown in the same figure, the Fe-Ni alloy has a temperature of 300-400°C, which is considered to be the operating temperature, during operation of the cathode support.
In the temperature range of 0° C., the one that exhibits the lowest expansion characteristics and is commonly used is a 42% FeNi alloy. Therefore, the purpose of this invention (Gl in the center cathode support and both side cathode supports)
(-), it is most suitable to use a 42% Fe-Ni alloy for both side cathode supports and a 45% Fe-Ni alloy for the center cathode support. However, the Gl electrode.

Depending on the shape and material of the cathode, eyelet, and other electrodes, there are cases where it is not necessary to reduce the coefficient of thermal expansion of the cathode support. Judging from Figure 6 above, those with an allowable coefficient of thermal expansion between 3oo and 400'C are FeNi 35% alloy and Fe-
It is a 50% Ni alloy.

In the first embodiment described above, the Ni content of the center cathode support was lower than that of the cathode supports for both sides.
Although the Ni content in the FeNi alloy was set to +3%, if the structure of the electron gun and the Ni content considered as the base are changed, the difference in the Ni content mentioned above will change sufficiently, including the It is possible to do so. In other words, as shown in Figure 6, at a thermal expansion coefficient of 300 to 400°C, F
Since the e-Ni 42% alloy exhibits the lowest coefficient of thermal expansion, Ni
When the content range is set to 35 to 50%, the difference in Ni content that indicates the maximum difference in thermal expansion coefficient is IIIX +8%.

Therefore, N in the Fe-Ni alloy constituting the center cathode support and both side cathode supports
Set the difference in i content within IIIIX +8%, and
It is set within the above range, taking into consideration the direction of out-of-plane deformation of one electrode and the amount of deformation.

Next, the operation of the configuration of the first embodiment described above will be explained with reference to FIGS. 1 and 7.

First, when the electron gun is operating, the heater (
Due to the heat generation of la), (lb), (lc), the cathodes (2a), (2b), (2c) are at least about 7
The temperature rises to 20℃, but at this time the eyelet (3a
), (3b), (3c) are heated to at least about 400°C, and cathode supports (4a), (4b)
, (4c) also increases the temperature to at least 200-300°C. Due to such a temperature rise, each component such as the cathode, eyelet, and cathode support, which are usually made of metal materials, naturally undergoes thermal expansion and deforms out of plane toward the Ctl electrode G2 electrode. The amount of out-of-plane deformation at this time is several μ
However, as shown in Figure 1, the amount of thermal expansion of the center cathode support in the Z direction is slightly larger than that of the cando supports for both sides, so as a result, the center cathode support The distance between the electrode and the 61 electrode, and the distance between the cathode support for both sides and the Gl electrode do not change before and after the operation of the electron gun. Therefore, R
, G, and B have almost the same rise, and the white balance characteristics are also improved.

The operation of the configuration of the second embodiment described above will be explained with reference to FIGS. 2 and 7. The amount of thermal expansion in two directions of the cathode supports for both sides is the same as the amount of thermal expansion of the cathode support for the center. As in the case of the IF embodiment, the distance between each cathode support, each portion of the Gl electrode, and each cathode support does not change before and after operation of the electron gun. Therefore, the rise of the current amount for R, G, and B becomes almost the same, and the white balance characteristics are also improved.

[Experiment example]

Next, an electron gun was created using the following alloys (■) and (■) as constituent materials for forming the side cathode supports and the center quad support as shown in FIGS. 7 and 8, and each cathode support was An experiment was conducted to measure the amount of thermal expansion and the distance between Gl-.

■Alloy used for side cathode support: Fe-Ni
42% alloy thermal expansion coefficient 49.8XlO'(/'C) ■Alloy used for center cathode support: Fe-Ni 45% alloy thermal expansion coefficient 68.4XlO'(/'C) Note that the above The coefficient of thermal expansion of the alloy is a measurement result between 30 and 300°C.

According to the electron gun obtained by fabricating each cathode support using the alloys of ■ and ■ above, as shown in Figure 1, the amount of thermal expansion in the Z direction of the center cathode support is greater than that of the cathode support for both sides. It is several microns larger than the amount of thermal expansion of the support in two directions. Since this amount cancels out the several micrometers of out-of-plane deformation of the Gl electrode (5), the gap between Gl- and R9G, B Both are equal.

In this way, the installation interval for Gl- before the heater heats up is R,
G and B are both equal, and as shown in Figure 3,
The amounts of R, G, and B beam currents from when the heater is turned on to a thermal equilibrium state are approximately the same, and a good white balance characteristic that always rises to the set chromaticity is exhibited.

In addition, in the above experimental example, the G1 electrode (5) is 62 electrodes (6
) side, but the Gl electrode (
Due to the structure of 5), as shown in Figure 2, there are cases in which out-of-plane deformation occurs on the cathode side.In this case, contrary to the above experimental example, the center cathode support By increasing the Ni content of the Fe-Ni alloy used for the side cathode supports (4a) and (4c) than the Ni content of the Fe-Ni alloy used for (4b), the center cathode support (4b) has a higher Ni content. By increasing the amount of thermal deformation in the Z direction of the side cathode supports (4a) and (4c), the amount of out-of-plane deformation of the G1 electrode (5) in the Z direction, which is several μ-, can be offset. good.

In the above experimental example, the reason why the side cathode supports or the center cathode supports were made from Fe-Ni 42% alloy, and the side cathode supports or center cathode supports were made from Fe-Ni 45% alloy was based on the following empirical findings. It is based on fact.

That is, as shown in FIG. 5, the Fe-Ni alloy is
The coefficient of thermal expansion changes continuously due to a slight difference in the content of i, and the lowest coefficient of thermal expansion occurs when the Ni content is around 35%, and Fe-Ni alloys in this area generally , called Invar, is widely used as a material for shadow masks for cathode ray tubes.

Furthermore, as the Ni content decreases, the coefficient of thermal expansion decreases, but the Curie point temperature decreases, narrowing the temperature range in which it can be used as a low expansion material (for example, F
The Curie point of e-Ni 35% Invar material is approximately 280℃,
The Curie point of 42% Fe-Ni is approximately 340°C).

Incidentally, the rise characteristics (white balance characteristics) of the beam current 1 from the heater ON tend to become better as the material of the cathode support is made of a low-expansion material. Therefore, it is possible to use a 35% Fe-Ni alloy, but as mentioned above, this alloy has a low Curie point and 35% during operation.
If used in a cathode support that is expected to be heated to 00°C or higher, it will rather act as a high expansion material.

Based on the above-mentioned empirical facts, as a result of experiments with varying Ni content, it was found that around 42% Fe-Ni is the best.

However, when the cathode supports (4a), <4b), and (4c) are made using the Fe-N 142% alloy mentioned above, the Gl electrode (5) is deformed outside the city, resulting in white balance problems and problems with the cathode built-in value. problem occurs.

Therefore, the difference of several microns between the GIK spacing at the center cathode support (4b) and the GIK spacing at the side cathode supports (4a) and (4c) due to the out-of-plane deformation of the G1 electrode (5) can be offset by the center cathode support (4b). As a result of examining alloys suitable for side cathode supports (4b), we found that alloys suitable for side cathode supports (4i), (4c
) was used, and only the Ni content of the Fe-Ni alloy of the center cathode boat (4b) was changed to change its thermal expansion coefficient. , G, and B were determined, and the corresponding Ni content was found. The results are shown in FIG. In the figure, the dotted lines are both side beam currents, the solid lines are center beam currents,
It can be seen that the coincidence rate between both side beam currents and the center beam current deviates greatly due to a very small difference in the setting of the coefficient of thermal expansion.

From the above experimental results, it is estimated that the difference in spacing due to the off-center deformation of the G1 electrode (5) and other asymmetry between the center cathode support and the side cathode supports is very small, and this problem can be solved. To solve, N
It can be seen that FeN1 alloy is suitable because its coefficient of thermal expansion can be delicately controlled by adjusting the amount of FeN1.

Now, from the intersection of the dotted line and the solid line in Figure 4, R, G,
It turns out that the thermal expansion coefficient of the center cathode support with the same beam current amount of B is 6.8 XIO' (/℃), and the Ni content that gives such a thermal expansion coefficient is 4.
It turns out that it is 5%.

In addition, the Ni content of the Fe-Ni alloy used for the cathode supports for both sides and the cathode support for the center in the above-mentioned examples is not limited to that of the first example or the second example; It is sufficient that the Ni content in the alloy is within the range of 35 to 50%, and the difference in the Ni content of the Fe-Ni alloy used for the cathode supports for both sides and the cathode support for the center is within ±8%. In particular, for an electron gun in which the Gl electrode is deformed out of plane toward the 62 electrode side, the Fe-Ni alloy used as the constituent material of the cathode support for both sides has a Ni content in the range of 41 to 43%. Desirably, N of the Fe-Ni alloy used for the center cathode support is
Good results can be obtained when the i content is within the range of 44 to 46%.

Furthermore, due to the structure of the Gl electrode (5), as shown in FIG.
In the case of out-of-plane deformation toward the cathode side, the Ni content in the Fe-Ni alloy forming the cathode supports for both sides and the Fe-N forming the center cathode support are determined.
It goes without saying that the Ni content in the i-alloy may be used in a reverse relationship.

[Effects of the Invention] As explained above, according to the present invention, the center cathode support and both side cathode supports in a cathode ray tube electron gun are made of Fe-Ni with a slight Ni content.
Since it has a simple structure made of an alloy, it can be implemented without making any major changes to the manufacturing process of conventional electron guns for cathode ray tubes, and the electron gun for cathode ray tubes with good white balance after the heater is turned on can be produced. A great effect can be obtained.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram schematically showing the state of thermal deformation in the Z direction in the cathode holding structure portion of an electron gun according to a first embodiment of the present invention, and FIG. 2 is a diagram showing a cathode of an electron gun according to a second embodiment of the present invention. A configuration diagram schematically showing the state of thermal deformation in the Z direction in the holding structure part, Fig. 3 is a graph showing the white balance characteristics of an electron gun according to an embodiment of the present invention, and Fig. 4 shows center beam current and side beam current. FeNi forming the center cathode support when
A graph showing experimental results for determining the Ni content in the alloy,
Fig. 5 is a graph showing the relationship between N1 content and thermal expansion coefficient of Fe-Ni alloy, and Fig. 6 is a graph showing the relationship between N1 content and thermal expansion coefficient of Fe-Ni alloy.
A graph showing changes in the coefficient of thermal expansion of Ni alloys, Figure 7 is a schematic diagram showing the main parts of an electron gun for cathode ray tubes, and Figure 8 is a graph showing changes in the thermal expansion coefficient of Ni alloys.
FIG. 9 is a graph showing the white balance characteristics of a conventional electron gun. FIG. 10 is a schematic diagram of the state of thermal deformation in two directions in the cathode holding structure of a conventional electron gun. FIG. (2a), (2b), (2c)--Cathode, (
3a), (3b), (3c) ---Eyelet,
(4a), (4c)... Side cathode support, (4b)... Center cathode support, (9)
...bead glass. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] (1) G1 to G4 electrodes, a plurality of cathodes provided close to the G1 electrode, a plurality of eyelets that hold each of the cathodes, and a plurality of eyelets that are welded and fixed to the bead glass and fixed to the bead glass. In a cathode ray tube electron gun equipped with a cathode support, each cathode support is formed of a Fe-Ni alloy with a Ni content of 35 to 50%, and each cathode support thermally expands with out-of-plane deformation of the G1 electrode. so that the distance between the G1 electrode and each cathode support does not change before and after the operation of the electron gun.
The Ni content in the Fe-Ni alloy of the center cathode support and both side cathode supports constituting the cathode support is set to be different so that the content difference between the two is within 8% at maximum. An electron gun for cathode ray tubes.