JPH0146987B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color picture tube, and more particularly to a color picture tube incorporating an in-line electron gun and correcting coma aberration of a deflection device mainly for the purpose of convergence free. . Next, the general structure of a color picture tube and the movement of an electron beam (hereinafter referred to as beam) will be explained with reference to FIG. That is, a panel 2 has a fluorescent screen 1 adhered to its inner surface.
, an envelope consisting of a funnel 3 connected to the panel 2, a net 4 and a stem 5, a shadow mask 6 disposed opposite to the phosphor screen 1, and the net 4.
It consists of an in-line electron gun 10 which is mounted inside the funnel and emits a central beam 7 and a pair of side beams 8 and 9, and a deflection device 11 fixed to the outer wall of the funnel 3 for the purpose of convergence free. By the way, in such a color picture tube, when the deflection device 11 causes the beams 7, 8, and 9 to draw a raster on the phosphor screen, the raster sizes drawn by each beam do not necessarily match; Generally, the raster size drawn by the central beam is smaller than the raster size drawn by the central beam, and this discrepancy in raster size is mainly due to the comatic aberration of the deflection device 11.
In order to solve this coma aberration and make each raster size almost the same, the tip of the electron gun
2 is provided with a control device made of a magnetic member at the position where the horizontal and vertical deflection magnetic fields formed by the deflection device 11 reach, and the leakage magnetic field of the deflection device 11 is caused to interfere with this control device, so that the side beams 8 and 9 are A method is used to increase the deflection sensitivity of the center beam 7. This control device is a field controller (F.
C), and is formed from the structure shown in Figure 2, for example. That is, the FC is usually made of a plate-like magnetic material that sandwiches the central beam passage hole 22 formed in the convergence electrode 21 fixed to the grid electrode closest to the phosphor screen of the electron gun in the short axis direction of the phosphor screen. The first control elements 25 and 26 are usually formed in a circular shape, and the second control element 2 is formed into a plate-like ring made of a magnetic member so as to surround the pair of side beam passage holes 23 and 24.
7, 28, the first control element 25, 2
6 increases the deflection sensitivity of the center beam 7 to that of the side beams 8 and 9 for the horizontal deflection magnetic field of the deflection device, and increases the deflection sensitivity of the center beam 7 to that of the side beams 8 and 9 for the vertical deflection magnetic field. It has the effect of further reducing Also, the second control elements 27, 28
has the function of strongly shielding the side beams 8, 9 in particular from the horizontal deflection magnetic field of the deflection device, and lowering the deflection sensitivity of the side beams 8, 9 to the horizontal deflection magnetic field than that of the center beam 7. These first control elements 25 and 26, and second control element 2
The installation position, shape, and dimensions of 7 and 28 are determined by the characteristics of the deflection device. In the figure, the solid line 29 shows the horizontal deflection magnetic field distribution, and the broken line 30 shows the vertical deflection magnetic field distribution. That is, the second control elements 27 and 28 primarily shield the horizontal and vertical deflection magnetic fields acting on the side beams, and reduce the coma aberration of the horizontal and vertical deflection magnetic fields by reducing the side beam raster size. It can be said that this second control element 2
As the outer diameters of the deflection devices 7 and 28 are increased, the amount of coma correction of the deflection device changes as shown in Fig. 3, with the relationship shown by the solid line 31 when using a horizontal deflection magnetic field, and the relationship shown with the broken line 32 when using a vertical deflection magnetic field. There is a relationship. In addition, the first control elements 25 and 26 primarily serve to emphasize the horizontal magnetic field acting on the center beam and reduce the coma aberration of the deflection device during horizontal deflection. As the outer diameters of 25 and 26 are increased, the amount of coma aberration of the deflection device increases as shown in Fig. 4, and the amount of coma aberration due to the horizontal deflection magnetic field decreases to the solid line 3.
3, and the relationship due to the vertical deflection magnetic field is as shown by the broken line 34. However, in Figures 3 and 4, the installation position of the first control element and the second control element, the plate thickness, and the inner diameter of the second control element are the same, and only the outer diameter is changed to correct it. We sought the relationship with quantity. To explain further, a deflection device used for a device with a large deflection angle such as a 110° deflection color picture tube inevitably has large coma aberration in the horizontal and vertical deflection magnetic fields. Control element 2
As the outer diameters of 7 and 28 are increased, the vertical deflection magnetic field has the effect of shielding the magnetic field acting on the side beams and at the same time emphasizing the magnetic field acting on the center beam, as shown by the broken line 32.
The amount of comatic aberration correction with respect to the amount of change in the outer diameter of the second control element increases rapidly, and on the other hand, the horizontal deflection magnetic field produces a shielding effect of the magnetic field acting on the center beam, as shown by the solid line 31. , second
The amount of coma aberration correction with respect to the amount of change in the outer diameter of the control element becomes saturated. Also, the first control elements 25, 2
Regarding 6, as shown in Fig. 4, the outer diameter change and coma aberration correction amount change almost linearly in the case 33 due to the horizontal deflection magnetic field, but the case 34 due to the vertical deflection magnetic field.
The amount of coma aberration correction tends to decrease rapidly as the outer diameter increases. That is, as mentioned above, in wide-angle deflection color picture tubes, it is extremely difficult to appropriately correct coma aberration caused by horizontal and vertical deflection magnetic fields at the same time by simply adjusting the outer diameters of the first and second control elements. There is a drawback. SUMMARY OF THE INVENTION It is an object of the present invention to improve the various drawbacks of the conventional color picture tube and to provide a color picture tube equipped with a control member that can moderate the coma aberration of the deflection device even in a wide-angle deflection color picture tube. . Next, one embodiment of the color picture tube of the present invention will be described with reference to FIGS. 5 to 10. That is, the color picture tube has three unit electron guns 40B, 40G, 40 on a horizontal plane including the tube axis Z and the horizontal axis x.
It has three electron guns 40 in which R are arranged in parallel and a central unit electron gun 40G is arranged on the tube axis Z, and emits a central beam and a pair of side beams passing on both sides thereof. A convergence electrode 41 is provided on the beam emission end side of the electron gun 40 .
A deflection device 42 is disposed in front of the electron beam in the beam traveling direction, and a control member made of a magnetic member is provided in the electron beam passing region between the deflection device 42 and the convergence electrode 41, to which the rear magnetic field 43 of the deflection device 42 extends. 44 are provided. The control member 44 has a structure shown in FIGS. 6 to 8. That is, the control member 44 made of a magnetic member is composed of a plate-like ring body 45 having the same shape as the conventional second control element, and a cylindrical body 46 integrally formed with the plate-shaped ring body 45. They may be press-formed at the same time, or they may be made separately and welded later. In this case, the inner diameter of the plate-shaped ring body 45 and the cylindrical body 46
The inner diameters of the beams should be approximately the same, and when welding, it is desirable to have a smooth finish as any burrs will affect the beam. The central axis of the cylindrical body 46 of this control member 44 is connected to both side beams 8,
9 is positioned so that it passes through. In the figure 7
is the central beam. The control member 44 is connected to the bottom part 41 of the convergence electrode 41 as shown in FIGS. 7 and 8, for example.
A plate-shaped ring body 45 is fixedly attached so as to surround both side beam passage holes 47 and 48 of ₁ , and the outer diameter B of the cylindrical body 46 is is formed to approximately 1/2 the size. In the figure, C indicates the distance between the central axes of the side beam passage holes 47 and 48, and D indicates the height of the cylindrical body 46. Next, FIG . 9 and FIG. To explain with reference to FIG. 10, the plate-shaped ring body 4
As the outer diameter A of 5 is increased, the side beam 8 due to the vertical deflection magnetic field is as shown by the broken line 52.
Since the effect of shielding the magnetic field acting on the center beam 7 and at the same time emphasizing the magnetic field acting on the center beam 7 is produced, the amount of correction for coma aberration with respect to the amount of change in the outer diameter of the plate-like ring body 45 increases rapidly. As shown by the solid line 51, due to the deflection magnetic field, the shielding effect of the magnetic field acting on the center beam 7 appears, so the amount of correction for coma aberration with respect to the amount of change in the outer diameter of the plate-shaped ring body 45 saturates after a while. It is similar to that in Figure 3, but in this example, this outer diameter that begins to saturate
By determining the outer diameter _A1 , which is in the saturation region from _A0 , based on the relationship with the distance C between the side beam passage holes 47 and 48, only the coma of the vertical deflection magnetic field can be determined independently. . Also, in this state, by changing the height D of the cylindrical body 46 as shown in FIG. 10, the solid line 53
As shown in the figure, they can be determined almost independently. At this time, the vertical deflection magnetic field hardly changes with the height D as shown by the broken line 52. That is,
The cylindrical body 46 has the effect of shielding the rear magnetic field acting on the side beam with respect to the rear magnetic field of the horizontal deflection magnetic field, and by increasing the height D, the area of action that shields the rear magnetic field becomes longer. Therefore, the amount of correction of the coma aberration of the horizontal deflection magnetic field increases accordingly. Therefore, the height D of the cylindrical body 46 and the amount of correction of the coma aberration of the horizontal deflection magnetic field are approximately proportional. On the other hand, with respect to the rear magnetic field of the vertical deflection magnetic field, the side beam has the effect of shielding the rear magnetic field, so by increasing the height D of the cylindrical body 46, the action area that shields the rear magnetic field is becomes longer, and the amount of correction for comatic aberration of the vertical deflection magnetic field increases. Therefore, the side beam is approximately proportional to the height D of the cylindrical body 46 and the amount of correction of coma aberration of the vertical deflection magnetic field. Further, regarding the central beam, the shielding effect gradually increases by increasing the height D of the cylindrical body 46. In other words, near the central axis of the central beam, the magnetic flux density is high due to the cylindrical body, and as you move vertically from the central axis of the central beam, the magnetic flux density gradually decreases, causing the central beam to This is because the shielding effect increases relatively as the distance from the vicinity of the central axis passes. In other words, the central beam is already slightly deflected in the vertical direction by the action of the plate-shaped ring 45, and as a result, as the beam advances in the direction of travel, it gradually moves away from the central axis of the central beam. It will move to a region where the magnetic flux density of the rear magnetic field is small. In this way, by moving the central beam to a region with lower magnetic flux density, the central beam essentially becomes gradually more effective in shielding the rear magnetic field, and the strength of the rear magnetic field increases. Although it depends on the shape, etc., the height D of the cylindrical body 46 and the coma aberration of the vertical deflection magnetic field are generally inversely proportional. Therefore, the effect of the cylindrical body 46 is the sum of the effects that the center beam and the side beams each receive from the rear magnetic field of the vertical deflection magnetic field described above, and as a result, the height D of the cylindrical body 46 is increased. By increasing the height D of the cylindrical body 46, the shielding effect on the side beams gradually increases, that is, the effect is good for coma aberration, and the shielding effect on the central beam gradually increases by increasing the height D of the cylindrical body 46. That is, the coma aberration is canceled out by a certain amount by the effect in the bad direction. As a result, the amount of correction of comatic aberration that the cylinder 46 exerts on the center beam and the side beams with respect to the rear magnetic field of the vertical deflection magnetic field is constant regardless of the height D of the cylinder 46. As described above, by the above effect, it becomes possible to independently correct the comatic aberration of the horizontal deflection magnetic field by changing the height of the cylindrical body. As mentioned above, in the color picture tube of the present invention, by using the control device 44 consisting of the plate-like ring body 45 and the cylindrical body 46, the coma aberration of the horizontal and vertical deflection magnetic fields of the deflection device can be controlled to some extent independently. This increases the degree of freedom in the design of the deflection device, and depending on the relationship between the coma aberration amounts of the horizontal and vertical deflection magnetic fields, the coma aberration can be controlled without using the conventional first control element. This has the advantage that correction is possible.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing the schematic structure of a color picture tube and the movement of the center and side beams, Fig. 2 is an explanatory diagram of a typical field controller, and Fig. 3 is an explanatory diagram showing the outer diameter and coma of the second control element. FIG. 4 is a curve diagram showing the relationship between the outer diameter of the first control element and the amount of coma aberration correction; FIG.
6 is a perspective view of a control member used in the color picture tube of the present invention, FIG. 7 is a plan view of FIG. 6, and FIG. 8 is the same. 6 is a cross-sectional view, FIG. 9 is a curve diagram showing the relationship between the outer diameter of the plate-shaped ring body and the amount of coma aberration correction, and FIG. 10 is a curve diagram showing the relationship between the height of the cylindrical body and the amount of coma aberration correction. It is a curve diagram. 10 , 40 ... Electron gun, 11, 42... Deflection device, 25, 26... First control element, 27, 28
...Second control element, 44 ...Control member, 41...
...Convergence electrode.

Claims (1)

[Claims] 1. A convergence-free color picture tube in which a central beam and a pair of side beams emitted from an in-line electron gun are deflected horizontally and vertically by a deflection device placed in front of the central beam and a pair of side beams. , a control member composed only of a magnetic member consisting of a plate-shaped ring body and a cylindrical body integrally formed with the plate-shaped ring body is provided so as to surround the side beam at a position where the horizontal and vertical deflection magnetic fields formed by the deflection device reach. , the outer diameter of the plate-shaped ring body is set to a size such that the amount of comatic aberration correction by the horizontal deflection magnetic field is saturated and the amount of coma aberration correction by the vertical deflection magnetic field can be adjusted substantially independently, and the cylindrical body is made substantially 1. A color picture tube, characterized in that coma aberration of the deflection device is corrected by setting the height such that coma aberration due to a horizontal deflection magnetic field can be adjusted independently. 2. The color picture tube according to claim 1, wherein the inner diameter of the plate-shaped ring body and the inner diameter of the cylindrical body are approximately equal and are integrally formed by welding or press molding. 3. The collar according to claim 1, wherein the control member has a plate-shaped ring fixed to the bottom of the convergence electrode of the electron gun, and the cylindrical body extends in the emission direction of the side beam. Picture tube.