JPS63164145A - Cathode-ray tube - Google Patents

Abstract

PURPOSE:To improve the image quality, white uniformity and quality of a cathode-ray tube by magnetizing a magnetic ring from outside of the neck portion to produce the correction magnetic field so as to correct at least one of the spot shape, the landing and the static convergence. CONSTITUTION:A magnetic ring 4 is arranged between the pre-focusing lens and the main lens and magnetized as needed so as to correct the cross angle thetabefore passing through of the main lens of the three electron beams 3R, 3G, 3B. Thereby the correction of the landing and the spot shape can be enabled. And by arranging the magnetic ring 4 between the pre-focusing lens and the main lens and/or between the main lens and the converging plate 2 and magnetizing the ring as needed the correction of the static convergence can be enabled.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cathode ray tube, and in particular to an electron gun mounted therein.

[Summary of the invention]

The present invention relates to the structure of an electron gun for a cathode ray tube, in which a magnetic ring is arranged between a prefocus lens and a main lens and/or between a main lens and a convergence plate,
By magnetizing this magnetic ring from the outside of the neck, spot shape, landing, and static convergence can be corrected.

[Conventional technology]

In the case of the Trinitron (registered trademark) type in-line electron gun, the main lens of the electron gun is L, and the trajectories of three electron beams intersect the center of the main lens. However, in reality, due to variations in assembly precision and component precision, the trajectories of the three electron beams deviate from the ideal trajectory, resulting in (1) deviation of the 21 invergence on the fluorescent surface, and (it) spot shape. There are three main problems: <iii) the landing on the phosphor surface is shifted, resulting in deterioration of white uniformity. For this reason,
Conventionally, in order to correct the convergence of the electron beam,
Magnets already attached to the outside of the neck, such as 2P!
i8.4 pole, 6 pole, BMC (Blue Misco
nvergence＾1ignment Magnet
) It has been proposed to do this by placing magnets.

Specifically, in the case of a Trinitron (registered trademark) type cathode ray tube, vertical misconvergence (V 5tatic
Twisting of the electron beam (MC)
In order to correct this, a magnetized 4() correction magnet is placed outside the neck. Also, horizontal misconvergence (I(MC))
Misalignment in input direction and! ! ! Naomi Mis Convergence MC
) In order to correct the deviation of the electron beam in the vertical direction, the BMCii positive magnet!・Place it on the outside of the neck. This 8MC correction magnet consists of one main magnet and two auxiliary magnets, and the combined magnetic field does not act on the R beam and G beam positions, but acts only on the B beam position.

In addition, instead of using the above-mentioned magnetized correction magnet, a method has also been proposed in which an unmagnetized correction magnet is placed outside the neck and then the required magnetization is applied (Japanese Patent Laid-Open Publication No. 60-56337).

Also, regarding spot shape and landing correction,
This was done using a correction magnet placed outside the neck, but its effect was weak and a sufficient correction effect could not be obtained.

Note that a method has also been proposed in which a magnet is placed inside the cathode ray tube for correction, but the magnet in this case is intended for forming a focus magnetic field.

[Problem that the invention seeks to solve]

Among static convergence deviations, spot shape distortions, and landing deviations that are attempted to be corrected with a correction magnet,
Although it is possible to correct the static convergence deviation using a conventional correction magnet placed outside the neck, a satisfactory correction effect could not be obtained regarding spot shape and landing correction. In particular, landing misalignment is a major problem when manufacturing high-definition cathode ray tubes, and an improvement has been desired.

In view of the above-mentioned points, the present invention provides a cathode ray tube having a correction magnet that can satisfactorily correct not only static convergence but also spot shape and landing.

[Means for solving problems]

In the cathode ray tube (6) according to the present invention, the electron gun (1)
between the prefocus lens and the main lens and/or the main lens and the convergence plate (deflection plate) (2
), and the magnetic ring (4) is magnetized to form a correction magnetic field from the outside of the neck part (7) to change the spot shape, landing, and static. It is characterized by performing at least one correction during convergence.

The material of the magnetic ring (4) is Pe-Cr-Co.
5 Sea Fe-Co, Ni-Fe-Co, Ni-F
Ferromagnetic materials such as e, 8l-Ni-Co, and ferrite can be used.

[Effect]

According to the present invention, a magnetic ring (4) is arranged between the prefocus lens and the main lens to perform the required magnetization,
The cross angle θ (see Figure F) is corrected before the three electron beams (3R), (3G), and (3B) pass through the main lens, making it possible to correct the landing and spot shape. .

Also, between the prefocus lens and the main lens and/or
Alternatively, since the magnetic ring (4) is arranged between the main lens and the convergence plate to apply the required magnetization, it is possible to correct static convergence.

(Example) The electron gun (1) shown in FIG.
It is a registered trademark) type electron gun, and is called an in-line type electron gun with three cathodes KB and Ka arranged horizontally.
, KRs 5 (11i1 grid G 1 , G2
, G3, G4, Gδ and a convergence plate (deflection plate) (2). This electron gun (1) constitutes a unipotential electron lens, and! ? #t Grid GI and second grid G2 are cathode lenses, second grid G2 and third grid G3 are prefocus lenses, and third grid G3, fourth grid G4, and fifth grid G5 are main lenses. As shown,
Electron beams 3 (3B, 3G, 3R) emitted from the three cathodes KBKG and KR intersect at the center of the main lens, and then pass through the convergence plate (2).
The light is deflected by a light beam and concentrated again on a single point on the fluorescent surface.

In this embodiment, FIGS. 1, 2, and 3
As shown in the figure, Fe-Cr-Co is used in the third grid G3 located between the prefocus lens and the main lens.
A magnetic ring (4) having a circular cross section (see FIG. 7) is held and arranged by a retainer (5).

Similarly, Fe-Cr-
A magnetic ring (4) made of Co and having a circular cross section is held and arranged by a retainer (5). In addition, magnetic ring (4)
For example, as shown in Figure 8, the shape of the magnetic ring (4) is circular, but the cross section is square. As shown in Figure 10, use magnetic rings (4) with a rectangular cross section and partially thickened magnetic rings (4) with a partially thickened width at 90° intervals. can do.

Electron gun (1) with magnetic ring (4) arranged like this
For a cathode ray tube (6) having a Apply magnetism. Figure 4 shows an example of the arrangement of a multipolar electromagnet (8) for magnetization, and shows a magnetic ring (4
) corresponding to the neck part (12 pieces arranged at equal intervals on the outside of the sword. In the same figure, (9) shows the switch, and (10) shows the 11 sources for magnetization.

Next, referring to FIG. 6, a magnetizing device for magnetizing the magnetic ring (4)! As shown in the figure, which shows an example of (11), the signal from the video signal generator (12) is displayed on the fluorescent surface (13) of the cathode ray tube (6), and the landing measuring device (14), spot shape, landing and static convergence are measured using a convergence and spot shape measuring device (15) and an off-axis measuring device (!6). Then, the measurement results are calculated and controlled by the
17), and if there is a deviation to be corrected, take out the required control signal and manually input it to the variable current magnetizing power supply (10), then apply the required signal current to the electromagnet (10).
8) to magnetize the magnetic ring (4).

In the figure, (1B) is a sensor, and (19) is a camera.

Next, specific examples will be described depending on the object to be corrected.

f, Cross Angle Correction As mentioned above, the Trinitron (registered trademark 1!) type in-line electron gun has one main lens, and three electron beams (3) cross at the center of this main lens. ).

However, this cross angle deviates from the ideal state, resulting in convergence deviation and speed.

The pot shape is planned and the landing is misaligned.

This cross angle deviation is corrected by the following means.

Note that since there is a positive correlation between the cross angle deviation amount and the grooving deviation amount of the three beams, the landing deviation amount is also corrected at the same time.

1. a. Correction of axis deviation of G beam As shown in the plan view of Fig. 12A, if the actual cross position is deviated in the y-axis direction with the ideal cross position as the origin of the coordinate axes, As shown in B, a four-pole magnetizing electromagnet (8) is arranged outside the neck part (7) corresponding to the position of the magnetic ring (4) arranged in the third grid G3 for correction. In the 12th drawing, the broken line indicates the ideal trajectory of the electron beam (3), and the solid line indicates the actual trajectory of the electron beam (3).

When correcting this cross, the magnetizing device (1
1), while detecting the shift of the cross with the convergence measuring device (14), in the R, G, and B beams (3),
In particular, correction is performed for the G beam (3G) located in the middle. The operation for this correction is performed according to the flowchart shown in Fig. 20, and even if the focus voltage (EC4) is changed, the spot on the fluorescent surface of the G beam (3G) will change.
Repeat magnetization until the amount remains within a predetermined range. Note that the required amount of magnetization is calculated based on the relationship between the amount of movement of the spot and the amount of current flowing through the magnetizing electromagnet (8) in advance, as shown in FIG. 21, and this data. Further, even if the position of the cross is shifted in the vertical direction, that is, in the Z-axis direction, it can be corrected in the same manner as above.

1, b, correction of deviation between R beam and B beam First, the 13th
As shown in the plan view of Figure A, after correcting the axis deviation of the G beam (3G), the remaining R beam (3R) and B beam (
3B) is symmetrically shifted, the magnetic ring (4) arranged in the third grid G3 as shown in Fig. 13B.
For magnetization of 4 poles on the outside of the neck part (7) corresponding to the position of ? Arrange IIm stones (8) to form the required correction magnetic field, and R
The beam (3R) and B beam (3B) are corrected at the same time. The amount of deviation between the R beam and the B beam is detected by measuring the amount of spot movement when the focus voltage (EC4) is changed by a unit voltage (for example, 1 kV) using a convergence measuring device (1 kV).
5) For example, for a cathode ray tube made of
If the spot shape does not occur even if the R beam is moved to the right by 0.1 fl and the B beam is moved to the left by 0.1 m (-0.1 m), the spot shape shown in Figure 22 is shown. Magnetization for correction is repeated according to the flowchart until the spot movement amounts of the R beam and B beam fall within the above-mentioned predetermined range.

Next, as shown in the plan view of FIG. 16A, a G beam (3G
) After correcting the misalignment of the R beam (3R), for example,
If only the neck part is asymmetrically shifted with respect to the B beam (3B), as shown in FIG. 16B, the neck part (7
) A two-pole magnetizing electromagnet (8) is arranged outside of the R beam (3R) to perform magnetization to form a magnetic field that moves the position of the R beam (3R) in the direction of the arrow. In this way, among the three beams, 1
By mainly moving the book beam, the G beam (3G) and B beam at the fluorescent surface (13) are
Distance H1 of the irradiation position of beam (3B) and G beam (3B)
Since it is possible to correct the beam grouping regarding the distance H2 between the irradiation positions of G) and R beam (3R),
It is also possible to simultaneously correct the H1/H2 components that make the landing asymmetrical.

■ Correction of static convergence + I , a. Correction of twist As shown in Figure 18A, R beam (3R) and B beam (3B)! Since the ilt paths are at opposite angles to each other around the G beam (3G), they do not intersect at a single point at a predetermined position on the screen, so there are three beams as shown in No. 181fiB! A so-called vertical misconvergence (V staticMC) occurs. In this case, as shown in FIG. 18C according to the flowchart in FIG. An electromagnet (8) is arranged to perform magnetization for correction. In this correction as well, the amount of magnetization f shown in FIG.
f (11), while measuring with a convergence measuring device (15). In addition, if the B beam (3B) in the R beam (3R) is deviated in the opposite direction to that in Figure 18A, arrange the four-pole electromagnet (8) as shown in Figure 18 to ensure that each is normal. move it to a suitable position. Incidentally, the magnetization for this twist correction can also be performed on the magnetic ring (4) arranged within the fifth grid G5.

u, b, HMc and VMC (7) correction As shown in Figure 14A, the orbits of the R beam (3R), G beam (3G), and B beam (3B) are aligned on the horizontal line, but the B beam In the case of so-called horizontal misconvergence (HMC), in which the concentration point of only the B beam (3B) on the fluorescent surface is shifted because the position of (3B) is shifted from the predetermined position (see Figure 14B), As shown in FIG. 14C, there are two poles for magnetization on the outside of the neck part (7) corresponding to the position of the magnetic ring (4) arranged in the fifth grid G5. ! ! A magnet (8) is arranged, and magnetization for correction is performed while measuring with a convergence measuring device (15).

In addition, as shown in FIG. 15A, the R beam (3R) and the G beam
Beam (3G) is in place but B beam (3B)
In the case of so-called vertical misconvergence (VMC), in which the B beam (3B) is shifted from the center point of the chisel because the center point of the B beam (3B) is shifted in the vertical direction (see Figure 5C), the A three-pole magnetizing magnet (8) is arranged outside the neck part (7) corresponding to the position of the magnetic ring (4) arranged in the five-grid G5 to perform magnetization for correction.

Note that when horizontal misconvergence and vertical misconvergence exist at the same time, both are magnetized to form a composite magnetic field, and correction is performed simultaneously.

11. Correction of c, M axes As shown in the plan view of Figure 19A, the G beam (3G) is horizontally shifted from the central axis (21) of the purity, causing mislanding on the fluorescent surface. , if good purity cannot be obtained, as shown in FIG. A magnetizing electromagnet (8) is arranged, and each R, G, B beam (3R), (
3G) and (3B) to a predetermined position at the same time to form a correction magnetic field. (26)
shows the trajectory of the B beam (3B) after correction. In this correction, the amount of deviation is measured using an off-axis measuring device (16) and a convergence measuring device (15).

Also, the G beam (3G) is the central axis of purity (21)
Even if there is a vertical deviation from
As shown in the figure, the correction is performed by applying the required magnetization to the magnetic ring (4) placed in the fifth grid 05. Note that the G beam (3G) is horizontally and vertically from the central axis (21) of the purity. If there is a deviation in the direction, correction is performed simultaneously by applying both magnetizations and forming a composite magnetic field.The magnetization for correcting these VMC, HMC and off-axis Magnetic ring placed inside G3 (
4) may also be used.

In addition, a magnetized bag! (11) Landing measuring device (
14) is used when correcting the landing since there may be a landing deviation after the static convergence correction.

If the electron gun needs to perform both cross correction and static convergence correction, should they be used for each correction? I
! The magnetic ring (4) is magnetized by the magnet (8) with a magnetic flux density as shown in Fig. 5A (see Fig. 5C for the method of measuring the magnetic flux density distribution). is 2I
Magnetic field distribution of fI electromagnet (8) °, (23) is magnetic field distribution of 4-pole electromagnet (8), (24) is 6-pole electromagnet (8)
The magnetic field distribution of each is shown. However, since magnetization is performed on the same magnetic ring (4), the magnetic field distribution of these three buildings (22), (23), (24) as shown in Figure 5B is
A combined magnetic field distribution (25) is formed in the magnetic ring (4).

Although the above embodiment has been explained using a unipotential type electron gun as an example, the present invention can be similarly applied to a pi potential type electron gun. That is, in the case of the four-pole pi-potential type electron gun (1) shown in FIG. 11, a magnetic ring (4) is arranged in the third grid G3, and corrections for spot shape, landing, and static convergence are performed here. In addition, a magnetic ring (4) is arranged within the fourth grid G4 so that magnetization can be performed here to perform correction for static convergence.

【Effect of the invention〕

According to the present invention, it is possible to correct the distortion of the spot shape due to the cross angle deviation and the axis deviation of the electron gun, thereby significantly improving the image quality. It also enables landing correction, which improves white uniformity.
The overall quality of character display monitors and broadcast station monitors can be improved. Furthermore, although the present invention allows correction of static convergence to be performed well in the same way as in the conventional case, according to the present invention, when a cathode ray tube becomes defective and is replaced, correction for static convergence, etc. has already been made. This is very advantageous for repairs, since the cathode ray tube that has been damaged can simply be replaced. As described above, according to the present invention, it is possible to correct any of the spot shape, landing, and static convergence, and a high-quality cathode ray tube can be manufactured, thereby improving the yield in the cathode ray tube manufacturing process.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the main parts of the cathode ray tube, Figure 2 is a front view of the third grid, fpJ31g+ is a cross-sectional view of the third grid, Figure 4 is a diagram showing the multipolar electromagnet, and Figure 5 is the magnetized state. FIG. 6 is a configuration diagram of the magnetizing device, and FIGS. 7 to 10 are diagrams for explanation.
The figure is a diagram of a magnetic ring, Figure 11 is a configuration diagram of a pi-potential lens, Figures 12 and 13 are diagrams used to explain cross angle correction, and Figure 14 is a diagram used to explain HMC correction. , FIG. 15 is a diagram used to explain VMC correction, FIGS. 16 and 17 are diagrams used to explain cross angle correction, FIG. 18 is a diagram used to explain twist correction, and FIG. 19 is a diagram used to explain twist correction. Diagram 2 for explaining axis correction
0 is a flowchart showing the correction method, FIG. 21 is a graph showing the measured spot movement amount, and FIGS. 22 and 23 are flowcharts showing the correction method. (1) is an electron gun, (2) is a convergence plate, (
3B), (3G), and (3R) are beams, (4) is a magnetic ring, (6) is a cathode ray tube, and (8) is an electromagnet. Figure 5 Explanation of the five-legged form. Figure 11: Cross-angle precision explanation Figure 12 Figure 1 - IMG's explanation of Nansho's date, month, 1, 13 Whistle 14 [
Cocross 7 n gamma le's expert message 5 L Ming to Ihei 13 Kuni No. 13 VMC me introduction Ichimasa's explanation B month 1; Charice chair 3 figure 10
Fig. Kuromata Aang) L//1 犀＾correct〆体clearl; Provided ``'rJ Fig. A B'' twist r+; Flowchart showing the method for removing T5 manure. Figure 20. Initial measurement of dust. 1 square square loaf, 7 flowchart Figure 23

Claims (1)

[Claims] A magnetic ring is disposed between the prefocus lens and the main lens and/or between the main lens and the convergence plate to correct at least one of spot shape, landing, and static convergence. A cathode ray tube comprising an electron gun in which the magnetic ring is magnetized from outside the neck portion to form a magnetic field.