JPH09199053A - Cathode-ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cathode-ray tube suppressing the deterioration of the focusing characteristic of an electron beam, having a wide convergence correction range, and requiring no separate fixing jig by arranging a pair of ring-like symmetrical correcting magnets apart from each other on the rear side (electron gun side) of a deflection yoke. SOLUTION: A pair of ring-like symmetrical correcting four-pole magnets 13a, 13b are arranged on the neck section 10a of a cathode-ray tube 1 apart from each other across a two-pole magnet 15 and a six-pole magnet 14 on the opposite side of a deflection yoke 16 to the tube face 10b and on the tube face 10b side of an electron gun than a main electron lens 4. The cathode-ray tube 1 capable of correcting convergence in a wide correction range while suppressing the deterioration of focusing and allowing the normal magnet fixing jig to be used as it is for fixing is obtained because two four-pole magnets 13a, 13b are arranged together with other correction magnets on the neck section 10a side of the deflection yoke 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode ray tube provided with a correction magnet capable of correcting predetermined convergence while suppressing deterioration of focus characteristics of an electron beam.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 7, a neck portion 10a of a cathode ray tube (CRT) has a ring shape as a means for adjusting the trajectories of three electron beams emitted from an electron gun 11. The 6-pole magnet 14, the 4-pole magnet 13, and the 2-pole magnet 15 are widely used. These correction magnets are externally fitted to the rear side (electron gun side) of the deflection yoke 16 and fixed by a fixing metal fitting 17.

The two-pole magnet 15 is used to move the three electron beams as a whole in the x direction, and the four-pole magnet 13 is a green magnet as shown in FIGS. 8 (A) and 8 (B). The 6-pole magnet 14 is used to correct the symmetrical misconvergence components of the positions of the red, blue, and both beams with respect to the beam, and the 6-pole magnet 14 is used to correct those asymmetric components.

Of these, there are the following two main methods of using the 4-pole magnet other than the above. The first method is to provide one on the rear side of the deflection yoke and set Vst (Vertical
This is a method of correcting one of Static MisConvergence) and XBV. As shown in FIG. 9 (A), the Vst correction is to correct the red and green vertical dot intervals at the center of the screen. The XBV correction is to correct the bow vertical misconvergence on the X-axis as shown in FIG. 9B. In this XBV, the horizontal magnetic field is a pin (bow) magnetic field, and the left and right beams are generated by the neck twist.
It occurs when rotating as indicated by 0. Even if Vst is corrected by some method, XBV occurs if there is a vertical beam space at the deflection center.

The second method is to add one to the rear side of the deflection yoke.
V, one on the rear side of the main electron lens, a total of two, V
This is a method of simultaneously correcting st and XBV.

[0006]

However, in the first method, since the other remains after the correction of one, another means for correcting the other is required, and the focus deterioration due to the astigmatism after the correction is caused. It becomes a problem.

On the other hand, in the second method, since a jig (neck assembly) for fixing the rear four-pole magnet to the neck portion is additionally required, there is difficulty in cost and assembling / adjusting workability. The present invention has been made in view of the above circumstances, and suppresses focus deterioration, which is a problem when a 4-pole magnet is adopted, as much as possible, and has a wide correction range.
Moreover, it is an object of the present invention to provide a cathode ray tube which does not require a separate fixing jig.

[0008]

In order to achieve the above object, the present invention provides the following cathode ray tube. (1) A pair of ring-shaped symmetric correction magnets that symmetrically correct the side beam component of the three electron beams emitted from the electron gun of the cathode ray tube with respect to the central beam are provided, and the pair of symmetric correction magnets are A cathode ray tube characterized in that the cathode ray tube is arranged on the rear side (electron gun side) of the deflection yoke, and is also arranged apart from each other. (2) The cathode ray tube according to (1) above, wherein another ring-shaped correction magnet is arranged between the pair of symmetrical correction magnets. (3) The cathode ray tube according to the above (1), wherein a pair of symmetrical correction magnets are arranged on the tube surface side of the main electron lens of the electron gun.

The cathode ray tube of the present invention includes a pair of ring-shaped symmetrical correction magnets (four poles) for symmetrically correcting the side beam component of the three electron beams emitted from the electron gun of the cathode ray tube with respect to the central beam. Magnet). Such 4
By having a pair of pole magnets, Vst and XB
V can be corrected at the same time. In addition, since it can be integrated with the deflection yoke by arranging it on the rear side of the deflection yoke (electron gun side, the same applies below), a separate fixing jig (neck assembly) for fixing the 4-pole magnet is required. Not. Furthermore, the farther the distance between the 4-pole magnets is, the more Vs
Since the correction sensitivities of t and XBV are increased, the correction range can be expanded by arranging them separately from each other.

In order to secure a distance between the two 4-pole magnets, it is advantageous to arrange a 2-pole magnet or a 6-pole magnet between these 4-pole magnets. Further, when the symmetry correction is performed by one quadrupole magnet, the three electron beams are respectively subjected to astigmatism and focus deterioration occurs, and the focus deterioration increases as the correction amount increases. However, when two quadrupole magnets are used, the directions of the magnetic fields produced by the two magnets are opposite, so that the effect of canceling the astigmatism generated on the one side works on the other side, and as a result, focus deterioration is reduced. You can In this case, the reduction of the focus deterioration is a condition that the arrangement of the three electron beams does not change between the front and rear quadrupole magnets.

For this reason, in a cathode ray tube having an electron gun of a type in which three electron beams intersect and side beams are switched in the main electron lens, both of these two quadrupole magnets are placed in front of the main electron lens (tube surface). By arranging it on the side), it is possible to surely reduce the focus deterioration.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the cathode ray tube of the present invention will be specifically described below. FIG. 1 is a side view of the external appearance showing an embodiment of the cathode ray tube of the present invention, and FIG. 2 is an enlarged view of the neck portion thereof.

The cathode ray tube 1 is a so-called trinitron type cathode ray tube, and is shown in a neck portion 10a of a tube body 10 as shown in FIG.
An electron gun 11 (not shown) is arranged in the. A beam twist coil 12 is externally fitted to the neck portion 10a, and the front side of the electron gun (tube surface (panel surface) 10b).
Side) neck portion 10a from the rear side to the rear side 4-pole magnet 13a, 6-pole magnet 14, 2-pole magnet 15,
The front four-pole magnet 13b is externally fitted in this order, and a deflection yoke 16 is arranged at the base end of the front neck portion of the series of correction magnets. The series of correction magnets are integrated with the change yoke 16. It is configured. A metal band 18 for explosion-proof reinforcement is fitted on the side wall of the panel.

The electron gun 11, as shown in FIG.
G4A, G4C, G4B, and G5 (G1 and G2 are omitted), each of which includes G4A, G4B, and G4.
The electrode of C constitutes the main electron lens 4. The three electron beams of R, G, and B emitted from the electron gun 11 intersect at the main electron lens 4, and the side beams of R and B are exchanged.
Then, after the trajectory is corrected by the series of correction magnets 13a, 14, 15, 13b, it is deflected by the deflection yoke 16 and the predetermined phosphor coated on the inner surface of the panel surface 10b is caused to emit light.

The characteristic of the cathode ray tube 1 is that two 4-pole magnets are used and the two 4-pole magnets 13a and 13b are used.
Are separated from each other with a two-pole magnet 15 and a six-pole magnet 14 interposed therebetween, and these two four-pole magnets 13a and 13b are on the rear side of the deflection yoke 16 and the main electron lens of the electron gun 11. It is arranged in front of 4. The separation distance between the two 4-pole magnets 13a and 13b is appropriately selected and is, for example, about 15 mm.

Since two quadrupole magnets are used, the cathode ray tube 1 can simultaneously correct Vst and XBV. In addition, since the two 4-pole magnets are both arranged behind the deflection yoke together with the other correction magnets, it is possible to use the ordinary metal fixtures for fixing the magnets as they are, and to integrate them with the deflection yokes. Therefore, it is not necessary to separately prepare a fixing jig as in the case of arranging on the rear side of the neck portion 10a, and cost reduction and assembly / adjustment workability are improved.

Next, the effect of separating the two 4-pole magnets from each other will be described. By operating the quadrupole magnet (changing the strength of the quadrupole), Vst and X
FIG. 3 shows how the relationship of BV changes for each of the front and rear quadrupole magnets. This FIG.
In the arrangement of the 4-pole magnets shown in FIGS. 1 and 2, the distance between the rear and front 4-pole magnets is about 15 mm, the state before correction is point A (Vst = XBV = 0), and point C (ΔXBV : +0.2 mm, ΔVst: -0.2 mm)
In this example, the black circle indicates the sensitivity of Vst and XBV of the rear quadrupole magnet 13a, and the white circle indicates the sensitivity of the front quadrupole magnet 13b.

When the rear four-pole magnet 13a is moved, A
The point moves in the direction indicated by the arrow in the figure, and Vst is corrected in the negative direction and XBV is corrected in the positive direction. Then, when the front side quadrupole magnet 13b is moved when the point B is reached, the point C is reached while Vst is corrected in the positive direction and XBV is corrected in the negative direction, and the desired correction can be achieved.

As can be seen from FIG. 3, the sensitivity of XBV with respect to Vst is different between the front side and the rear side. The correction of XBV and Vst using two 4-pole magnets uses this difference in sensitivity, and the more the distance between the two 4-pole magnets is increased (in the tube axis Z direction), the difference in sensitivity between Vst and XBV. Is increased, and as a result, the correction range can be expanded. In the present invention, the two-pole magnet and the six-pole magnet are interposed between the two four-pole magnets, and the distance between the two four-pole magnets is made as large as possible.

Next, the effect of arranging the two 4-pole magnets in front of the main electron lens of the electron gun will be described. One of the drawbacks of using a 4-pole magnet is that focus deterioration occurs. When symmetry correction is performed with a 4-pole magnet, the three electron beams are
Due to the Lorentz force as shown in FIG. 4, each receives astigmatism, and focus deterioration occurs. Each of the B, G, and R electron beams is subjected to astigmatism as shown in the lower part of the figure, causing halation around the core in the central portion and around it, resulting in focus deterioration. When only one quadrupole magnet is used, either Vst or XBV is corrected, but focus deterioration also increases as the correction amount increases. However, when two quadrupole magnets are used, the directions of the magnetic fields produced by the two magnets are opposite, so that the effect of canceling the astigmatism generated on the one side works on the other side, and as a result, focus deterioration is reduced. You can

However, this is based on the assumption that the arrangement of the three electron beams does not change between the front and rear quadrupole magnets.
When the side beams (red and blue) are exchanged between the front and rear quadrupole magnets, conversely astigmatism is strengthened and focus deterioration is increased. This corresponds to the case of arranging two quadrupole magnets in front of and behind the main electron lens in a so-called Trinitron CRT. In the trinitron type, since the three electron beams intersect at the main electron lens, the side beams are exchanged. Therefore, by arranging two quadrupole magnets both in front of the main electron lens of the electron gun, it is possible to reduce the focus deterioration caused by the correction by the quadrupole magnet even in the Trinitron type cathode ray tube which intersects the electron beams. You can

FIG. 5 schematically shows a comparison of the states of focus deterioration between the case where two quadrupole magnets are arranged together in front of the main electron lens and the case where they are arranged before and after the main electron lens. . FIG. 5A schematically shows the arrangement of each quadrupole magnet with respect to the main electron lens. FIG. 5B shows the action of force on the electron beam in each 4-pole magnet, and FIG. 5C schematically shows the state of focus deterioration in each 4-pole magnet. FIG. 5D shows that when two quadrupole magnets are both arranged in front of the main electron lens (in the figure, a quadrupole magnet is used), astigmatism is canceled and focus deterioration occurs. Less,
In the case where they are arranged before and after the main electron lens (in the figure, when a 4-pole magnet is used), astigmatism is amplified and focus deterioration increases.

The results of this experiment will be described with reference to FIG.
This figure shows the correction of XBV = 0.2mm for the degree of focus deterioration when two quadrupole magnets are placed both in front of the main electron lens and before and after the main electron lens in a Trinitron CRT. It is the result of comparison when doing. In the figure showing the spot shape of the electron beam viewed from the tube surface side, the outer peripheral line a is an isointensity curve of 10% with respect to the peak of the beam intensity, and the inner peripheral line b.
Is a 50% isointensity curve. In FIG. 6A, R,
Each of the G and B electron beams has a spot shape when it is not corrected by the quadrupole magnet, as shown in FIG.
Is a beam spot shape when two quadrupole magnets are arranged in front of the main electron lens. FIG. 6 (C)
Is a beam spot shape when two quadrupole magnets are arranged in front of and behind the main electron lens.

It can be seen from FIG. 6 that the focus deterioration is less when two quadrupole magnets are both arranged in front of the main electron lens than when they are arranged before and after the main electron lens. The embodiment described above mainly shows an example in which the present invention is applied to a so-called trinitron type CRT, but it goes without saying that the present invention can also be applied to other types of CRTs, and the arrangement of the correction magnets is also limited to the above aspect. However, the present invention can be variously modified without departing from the scope of the present invention.

[0025]

As described above, the cathode ray tube of the present invention can effectively correct the inconvenience caused by using the correction magnet that symmetrically corrects the trajectory of the side beam of the electron beam.

[Brief description of drawings]

FIG. 1 is a side view showing an appearance of a cathode ray tube of the present invention.

FIG. 2 is an enlarged view of the neck portion of FIG.

FIG. 3 is a graph showing a difference in correction sensitivity when two quadrupole magnets are separated from each other.

FIG. 4 is a schematic diagram showing a force applied to a beam in a quadrupole magnet and a state of focus deterioration.

FIG. 5 is a conceptual diagram showing that two quadrupole magnets have different states of focus deterioration depending on the arrangement with respect to the main electron lens.

FIG. 6 is a schematic diagram showing an experimental result showing that the states of focus deterioration are different depending on the arrangement of two 4-pole magnets with respect to the main electron lens.

FIG. 7 is a side view showing an arrangement of conventional correction magnets.

FIG. 8 is an explanatory diagram showing correction of a beam trajectory by a quadrupole magnet.

FIG. 9 is a conceptual diagram illustrating Vst and XBV.

FIG. 10 is a conceptual diagram illustrating a state in which XBV occurs.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cathode ray tube 4 Main electron lens 10a Tube surface (panel surface) 10b Neck part 11 Electron gun 13a Rear 4 pole magnet 13b Front 4 pole magnet 14 6 pole magnet 15 2 pole magnet 16 Deflection yoke

Claims (3)

[Claims] 1. A pair of ring-shaped symmetrical correction magnets for symmetrically correcting a side beam component of three electron beams emitted from an electron gun of a cathode ray tube with respect to a central beam, the pair of symmetrical corrections being provided. A cathode ray tube in which a magnet is arranged on the rear side (electron gun side) of a deflection yoke and is arranged apart from each other. 2. The cathode ray tube according to claim 1, wherein another ring-shaped correction magnet is arranged between the pair of symmetrical correction magnets. 3. A cathode ray tube according to claim 1, wherein a pair of symmetrical correction magnets are arranged on the tube surface side of the main electron lens of the electron gun.