JPS6311744B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electron gun assembly for a color cathode ray tube that emits three electron beams.

3 each of electron gun structures for color cathode ray tubes
The electron gun holds, for example, a cathode, a first grid electrode, a second grid electrode, a third grid electrode, a fourth grid electrode, etc. at predetermined intervals, and is assembled integrally with an insulating support made of porous glass or the like. There is. As a recent trend, the grid electrodes of the three electron guns to which the same voltage is applied are formed into a so-called integrated structure common to the three electron guns. For this reason, the signal input of the three electron guns uses a primary color drive method that is superimposed and added to the cathode potential, and as a result, the interval between the thermionic emission surface of the cathode and the first grid electrode is set extremely accurately. It must be. This also applies between the first grid electrode and the second grid electrode.

Maintaining accurate spacing between the electrodes is important not only for color cathode ray tubes but also for other cathode ray tubes. Normally, when an electron gun assembly is assembled into a cathode ray tube and operated, after the heater ignites, the cathode The temperature increases in the order of , the first grid electrode, and the second grid electrode. In this case, the temperature rise curves of the heater, cathode, first grid electrode, and second grid electrode are different, and therefore the electron gun assembly, especially the cathode and the first grid The spacing between the electrodes becomes significantly different from the value set at room temperature. In particular, if there is a difference in the spacing between the cathode and the first grid electrode in the three-electron gun for color cathode ray tubes, color shifts will occur on the screen after the color television receiver equipped with such a color cathode ray tube is switched on. This will seriously impair image quality.
Therefore, in the three-electron gun of a color picture tube, how to absorb or escape the elongation and strain of each part due to thermal expansion after heater ignition is an important issue in the structure of the electrodes that make up the electron gun structure. It is becoming.

Next, an example of an electron gun assembly used in a color cathode ray tube will be explained with reference to FIGS. 1 and 2.

That is, the cathode 2 containing the heater 1 is red R, green G,
Three grid electrodes for blue B are arranged in parallel at a predetermined interval in a straight line, and coaxially with the cathode 2 and spaced at a predetermined interval, a first grid electrode 3, a second grid electrode 4, a third grid electrode 5, A fourth grid electrode 6, a fifth grid electrode 7, and a sixth grid electrode 8 are implanted in order on the insulating support 9 at predetermined intervals, and the first grid electrode 3 to the fifth grid electrode
The grid electrode 7 is composed of one or more integrated electrode elements having a predetermined electron beam passage hole coaxially with the cathode 2 for red, green, and blue, and the sixth grid electrode 8 also has a predetermined hole. The center electron beam passage hole for green is coaxial with the cathode, but the electron beam passage holes on both sides for red and blue are slightly eccentric.
The electron beam of the book is focused on the aperture of the shadow mask, and is made to strike a predetermined phosphor layer of the phosphor screen.

Each electron beam passage hole of this electron gun structure is provided with an annular protrusion so as to be spaced apart from the opposing electrodes. It is designed to prevent mutual interference. Further, each electrode is provided with a planting portion on both sides in a direction perpendicular to a straight line connecting the centers of the electron beam passage holes, and is planted on the insulating support 9 via this planting portion.

The electron gun assembly described above is a so-called QPF type electron gun assembly having a composite main electron lens system, and an anode voltage is applied to the sixth grid electrode 8.
A stem pin 11 is implanted in the stem 10 by connecting the grid electrode 7 and the third grid electrode 5 with an internal conductor 12.
By applying 20 to 30% of the anode voltage and connecting the fourth grid electrode 6 to the second grid electrode 4 with the internal conductor 13, the third grid electrode 5, the fourth grid electrode 6, and the fifth grid electrode 7 are connected. This is an electron gun structure with extremely good characteristics, in which a unipotential electron lens is formed as an auxiliary electron lens, and a bipotential electron lens is formed as a main electron lens by the fifth grid electrode 7 and the sixth grid electrode 8. be.

Next, the first grid electrode 3 incorporated into such an electronic structure will be explained with reference to FIGS. 3 to 8.

That is, FIGS. 3 and 4 are assembly diagrams of the first grid electrode 3, and the main body 3a shown in FIGS. 5 and 6 and the support body 3b shown in FIGS. 7 and 8 are marked with an X. It is assembled by being fixed at welding points 30.

In such a first grid electrode 3, the implanted portions 31a, 31b, 31c, 31 provided on the support 3b are
d is fixed to the insulating support 9 and assembled, and the wider the distance between the planted parts 31a and 31b and between 31c and 31d, the more accurate the distance between the first grid electrode 3 and the second grid electrode 4 becomes. The parallelism between the first grid electrode 3 and the second grid electrode 4 is also accurate. However, even if the dimensions at room temperature are maintained accurately, the cathode 2,
After installing the heater 1 and connecting it to the stem 10, completing the color cathode ray tube through a general sealing and evacuation process, and relighting the heater 1, the implanted portions 31a and 31b, 31c and 31d of the first grid electrodes are are each supported between one insulating support 9, and between the implanted portions 31a and 31b and between 31c and 3.
If the interval 1d is wide, when the cathode 2 is heated by ignition of the heater, the temperature of the first grid electrode 3 will rise due to thermal radiation or the like. The temperature rise of the first grid electrode 3 is caused by heat conduction from the support piece (planted part) supporting the heater 1 and the cathode 2 via the insulating support body 9 in addition to this heat radiation. When the temperature of the first grid electrode 3 increases due to such thermal radiation or conduction, the first grid electrode 3 expands due to thermal expansion. In this case, the first
Stainless steel 1 which is the material forming the grid electrode 3
The thermal expansion coefficient α of 6-14 is α=176×10 ^-7 ,
On the other hand, the coefficient of thermal expansion α' of glass, which is the material of the insulating support 9, is α' = 24 × 10 ^-7 , which is a large difference, and even if materials with the same coefficient of thermal expansion are combined, the rate of temperature rise is not necessarily the same. However, dimensional differences due to thermal expansion coefficients and temperature differences inevitably occur, and the first grid electrode 3 warps in the direction in which the electron beam passage holes R, G, and B are arranged. To make matters worse, since the second grid electrode 4 is farther from the heat source than the first grid electrode 3, the point at which the temperature reaches (saturation temperature) and its rising temperature are slower than the first grid electrode 3. Similarly, as the third grid electrode 5, fourth grid electrode 6, etc. are further away from the heat source, the temperature increases, but the time is slow;
Although each electrode has a dimensional difference, the first grid electrode 3 and the second grid electrode 4 are particularly close to the heat source and are subjected to the strain, resulting in large deformation.

In this case, if the dimension between the planted parts 31a and 31b is large, the first grid electrode 3 fixed to the insulating support 9 by the two planted parts 31a and 31b will be damaged due to thermal expansion. Planting parts 31a, 31
It will curve back in an arc passing through b. The dimensional change due to this warping does not match the green electron gun in the center and the red and blue electron guns with electron beams on both sides. This is because the side wall 32a of the folded first grid electrode 3, that is, the side wall 32a of the shallow dish-shaped main body 3a, and the side wall 32b of the support body 3b have the cathode 2 side as the inner surface, so this warp is shaped like an arc with the second grid electrode side as the outer surface. Therefore, the dimension between the electron beam passage hole of the central green electron gun and the cathode is in the direction of widening, and the dimension between the electron beam passage hole of the red and blue electron guns on both sides and the cathode is the width of the center green electron gun. As a result, the cathode current ratio (IK ratio) of each electron gun (assuming 100% when stable) is as shown in Figure 9. The central electron gun is shown by a broken line 35, and the electron guns on both sides are shown by a solid line 36. In other words, for about 10 seconds to 3 minutes after ignition of the heater, the cathode size expands,
Since the dimension between the first grid electrode 3 and the cathode 2 is reduced, the current IK becomes larger. Next, it gradually decreases until the warp of the first grid electrode 3 is added, that is, from about 1 minute to 20 minutes. This is because the elongation of the cathode 2 stops (the temperature enters a stable region), and the temperature of the first grid electrode 3 rises and its dimensions change, causing warping, and the current starts to change in the direction of less than in the steady state. It's for a reason. The point where this effect is greatest is 3 minutes to 10 minutes after ignition.
The current is at its minimum at the quantile. At this time, the change in the green electron gun in the center is the largest, and the current is the smallest among the three electron guns. Therefore, the color of the color cathode ray tube at this time changes to a color without green, that is, a magenta color. As time progresses further, the temperature of the insulating support 9 increases, the dimensional strain is somewhat relaxed, and the current gradually recovers. During this time, the temperature of the second grid electrode 4 is gradually rising, but the apparent effect and current change are observed.
After about 20 minutes, the current gradually decreases, albeit slightly, from the point at which it exceeds the steady-state value and enters a stable region.
The change in the second grid electrode 4 overlaps with the change in the first grid electrode 3 in the first half and appears as a difference number, so that no independent effect can be seen, but it appears from the time when the change in the first grid electrode 3 stops in the second half. When the temperature of the first and second grid electrodes 3 and 4 assembled into an integrated structure increases faster than that of the third grid electrode 5, etc., the cathode current as shown in FIG. In particular, there was a problem in that the current change in the central green electron gun was large, causing color shift during switch-on.

The present invention was made in view of the above-mentioned problems, and an object of the present invention is to provide an electron gun assembly with good accuracy by reducing the initial color shift at the time of switch-on.

Next, one embodiment of the electron gun structure of the present invention will be described. However, since the structure as the electron gun structure is substantially the same as that shown in FIGS. This will be explained with reference to FIG.

That is, FIGS. 10 and 11 show the first grid electrode 43.
This is an assembly diagram of the shallow dish-shaped first grid electrode body 4 having almost the same structure as the conventional one shown in FIGS. 12 and 13.
3a and a first grid electrode support 43b shown in FIGS. 14 and 15 are assembled by fixing them at welding points 40.

To explain the first grid electrode support 43b, the implanted parts 44a and 44b are straight lines connecting the center green electron beam passage hole G and the centers of the red and blue electron beam passage holes R and B on both sides. The planting portions 44a, 4 are provided at the center on both sides in the direction perpendicular to the
4b is implanted in an insulating support. Furthermore, low step portions 45a, 45 are provided on both sides of the planted portions 44a, 44b.
b, 45c, and 45d, and this low step portion is held shallower than the implanted portions 44a, 44b when the implanted portions 44a, 44b are implanted on the insulating support, and The width is the outer width 46a, 46b of the lower step portions 45a and 45b and 45c and 45d.
keep it narrower, in this case the first grid electrode body 4
3a may also have stepped portions corresponding to the low stepped portions 45a, 45b, 45c, and 45d of the first grid electrode support 43b.

When the first grid electrode 43 having such a structure is implanted in an insulating support, the implanted portions 44a and 44b are implanted deeply, and the shallow protrusions 45a, 45b, 45c, 45 are implanted deeply.
d is also held shallowly on an insulating support at the same time.

The advantages of such a structure are as follows. That is, the planting portions 44a, 44b securely fix the first grid electrode 43 near the center, and the low step portions 45a, 4
5b, 45c, and 45d ensure the parallelism of the electrodes. That is, in the electron beam passage holes of the electron guns on both sides, low step portions 45a, 45b, 45c, and 45d are held slightly shallowly by an insulating support, and the first grid electrode, second grid electrode, cathode, heater, etc. Connect the grid electrodes to the assembled stem, complete the color cathode ray tube through the general sealing and evacuation process, and then relight the heater.The cathode current ratio (IK ratio) of each electron gun at the center and both sides (when stable) 100%) are those of the central electron gun indicated by the broken line 51 in Fig. 16, and the solid line 52.
It changes separately from that of the double-sided electron gun shown in .

That is, for about 10 seconds to 3 minutes after ignition of the heater, the cathode size increases, and the dimensions of the first grid electrode 43 and the cathode decrease, so the current IK can increase, but as the cathode temperature rises, the first grid electrode 43 also increases. Heat is transferred by thermal radiation, the temperature of the first grid electrode 43 rises, and the current decreases slightly until the dimensional difference due to thermal expansion of the support 43b of the first grid electrode 43 becomes stable. Since there is no deformation, the rate at which the current decreases is extremely low. Furthermore, by providing the second grid electrode with a similar structure, the effect thereof becomes undetectable in terms of current.

The reason for this is that the planting parts 44a and 44b are planted on the insulating support near the center, and the low step parts 45a, 45b, 45c, and 45d are held shallowly on the insulating support. The part has a weaker fixing force to the insulating support than the implanted part, and has a structure that protrudes from the insulating support 9.
The expansion of the dimensions of the first grid electrode 43 due to thermal expansion is caused by the fact that the lower steps around the implanted portions 44a and 44b slide on the insulating support and can escape to both sides in the width direction. There is one point for each of the provided portions 44a and 44b, and the first grid electrode 43 does not warp. Therefore, the flatness of the first grid electrode 43 is always maintained, so that no dimensional difference occurs between the first grid electrode 43 and the cathode.
In particular, there is no difference in characteristics between the central electron gun and the electron guns on both sides, and color shift does not occur during switch-on. Moreover, if the second grid electrode has a similar structure, the dimensional difference due to this electrode will also be eliminated.

In the embodiment, the support 43 of the first grid electrode 43
Planted parts 44a, 44b and low step part 4 on both sides of b
5a, 45b, 45c, and 45d have been described, but in this case, a planting part is provided on the support,
The first grid electrode may be formed by distributing low steps on the main body.

It is desirable to apply this kind of electrode structure to the second grid electrode as well, but normally the second grid electrode can be a single plate-shaped body, and the support used for the first grid electrode is generally Not necessary. Therefore, in the case of the second grid electrode, it is sufficient to provide a directly planted portion and a low step portion. The reason why the first grid electrode support is provided in the first grid electrode is that the first grid electrode body is formed of a thin plate in order to reduce the thickness of the plate around the electron beam passage hole provided in the first grid electrode body. The first grid electrode support is provided for strength. Therefore, if the thickness of the plate around the electron beam passage hole is not desired to be extremely thin, it is not necessarily necessary to separate the plate thickness into the main body and the support, and the thickness shown in FIGS.
Of course, the first grid electrode shown in Figure 1 can be formed from a single plate or a shallow dish, and in this case, it is sufficient to provide low steps on both sides of the implanted part. Become.

Furthermore, as a representative example of the electron gun structure, a high-performance one with an auxiliary lens and a main lens is shown.
Of course, this can also be applied to ordinary bipotential electron gun structures, unipotential electron gun structures, tripotential electron gun structures, and other electron gun structures.

As mentioned above, the electron gun structure of the present invention has a simple structure, but it can be used from switch-on to stable state.
It is possible to extremely reduce IK fluctuations,
Since a screen without color shift can be obtained, its industrial value is extremely large.

[Brief explanation of the drawing]

1 and 2 are diagrams showing an example of an electron gun assembly, in which FIG. 1 is a side view, FIG. 2 is a front view, and FIG.
8 to 8 are diagrams showing conventional first grid electrodes, FIG. 3 is a plan view of the first grid electrode, FIG. 4 is a front view of the first grid electrode, and FIG. 5 is a diagram of the first grid electrode. A plan view of the main body, FIG. 6 is a cross-sectional view of FIG. 5 taken along the line X ₁ - X ₁ , FIG. 7 is a plan view of the first grid electrode support, and FIG. A front view of the grid electrode support, and Figure 9 shows the IK from switch-on to stability when using the first grid electrode shown in Figures 3 and 4.
10 to 15 are curve diagrams showing changes, and are diagrams showing a first grid electrode adapted to an embodiment of the electron gun structure of the present invention. FIG. 10 is a plan view of the first grid electrode, and FIG. Figure 11 is a front view of the first grid electrode, and Figure 12 is a front view of the first grid electrode.
The figure is a plan view of the first grid electrode body, and Figure 13 is a plan view of the first grid electrode body.
A cross-sectional view of Figure 2 taken along the line X ₂ - X ₂ ,
FIG. 14 is a plan view of the first grid electrode support;
The figure is a front view of the first grid electrode support, and FIG. 16 is a curve diagram showing the IK change from switch-on to stable state when the first grid electrode of FIGS. 10 and 11 is used. 3, 43...first grid electrode, 3a, 43a...
First grid electrode body, 3b, 43b...first grid electrode support, 31a, 31b, 31c, 31d, 4
4a, 44b...planted part, 45a, 45b, 45
c, 45d...Low step.

Claims (1)

[Claims] 1. Between a plurality of insulating supports, a cathode, a first grid electrode,
A second grid electrode and another grid electrode are arranged at a predetermined distance from each other via the implanted part, and at least the first grid electrode and/or the second grid electrode are plate-shaped, shallow dish-shaped, or plate-shaped. In the electron gun assembly for a color cathode ray tube, the electron gun assembly for a color cathode ray tube is composed of an electrode of an integrated structure in which three electron beam passage holes are arranged in a row in a shallow dish-like combination body.
A pair of implanted portions deeply implanted into the insulating support at the center of each side in a direction perpendicular to a straight line connecting the centers of the electron beam passage holes of the grid electrode, and each of the pair of implanted portions. A low step portion that is held shallowly by the insulating support is provided on both sides of the electrode, and the sliding of the low step portion and the insulating support prevents the first grid electrode and/or the second grid electrode from warping. An electron gun structure for a color cathode ray tube. 2. The electron gun assembly for a color cathode ray tube according to claim 1, wherein the outer width of the low stepped portions provided on both sides of the implanted portion is larger than the width of the insulating support.