KR820001110B1 - Magnetizing apparatus and method for use in correcting color purity in a cathode ray tube and product thereof - Google Patents

Abstract

A CRT for color TV receiver includes a magnetic material located adjacent to a neck portion. A magnetizing appts. is used for establishing the color purity of three in-line electron beams within the CRT. The magnetizing appts. comprises >=2 elongated conductor loops arranged for positioning about the neck in proximity to the magnetic material and capable of being energised by a magnetizing current for creating permanently magnetised regions within the material. The magnetized regions produce a color purity magnetic field within the CRT for establishing the color purity of the three in-line electron beams.

Description

Magnetizer for color purity correction

1 is a plan view of a strip-shaped member and a magnetizer made of a cathode ray tube and a magnetic material according to the present invention.

FIG. 2 is an enlarged cross-sectional view of a portion of the cathode ray tube of FIG. 1 showing the color purity by three sets of inline beams of the cathode ray tube.

3 is a perspective view of the magnetization apparatus of FIG. 1 with a portion of the cathode ray tube and the magnetic material removed.

4 and 5 show magnetic lines of force generated by the magnetization apparatus of FIG. 3 and the magnetic force thereof.

6 to 11 show various generation forms of the magnetic field.

The present invention relates to color purity adjustment of a cathode ray tube for a color television receiver.

Color display devices, such as those used in color television receivers, have a cathode ray tube using three sets of electron beams modulated with color display video signals. These beams are projected through respective holes in the shadow mask to the respective color phosphor areas provided on the inner surface of the tube's image display screen. To accurately reproduce the color image, three sets of electron beams need to be focused on the screen at every point of the raster. In order to achieve color purity, the deflection center of each of these three sets of beams must be accurately positioned within the deflection plane of the yoke. If the deflection yoke is inaccurate or the deflection center is displaced due to factors such as the manufacturing tolerance of the electron gun or the attachment tolerance toward the neck of the electron gun, sometimes color mismatch occurs.

Many color purification devices have a structure that generates an adjustable magnetic field. These devices are arranged on the neck of the cathode ray tube, and the magnetic field is suitably adjusted so as to obtain an optimum color purity by the electron beam. This adjustment is done by moving the field generating element or by rotating the magnetized ring about the neck of the cathode ray tube or by rotating the cylindrical magnet about its axis.

In other color purity adjusting devices, such as those described in DOS 2,611,633, published on October 21, 1976, an unadjustable permanent magnetic field is produced. In the first step of this adjustment, an auxiliary device in which eight coils are arranged to form a circumference is arranged around the neck of the cathode ray tube. Appropriate value of direct current flows through the coil, and a magnetic field is generated to impart proper color purity by the electron beam. Data for the magnetizing device is generated by the value of the direct current, and in the second step, the magnetizing device is magnetized in the region of the seed-like member or the band-shaped member made of magnetic material which generates the above-mentioned unadjustable magnetic field. . When the magnetized strip-shaped member is attached to the neck of the cathode ray tube, the electron beam is adjusted to set the optimum color purity.

In the case of using such a band-shaped magnetic member, it is preferable to omit the use of an auxiliary device for determining a position to form the magnetization region in the band-shaped member. Magnetizers that do not use such an auxiliary device should have a magnetization portion arranged so that it can be finished with a simple operation when directly performing a color purification operation.

In an inline cathode ray tube with a slotted shadow mask with slot holes extending vertically using three sets of inline electron beams, color purity adjustment may be achieved by simply moving all three sets of beams in the same horizontal direction. The magnetic field produced by the permanently magnetized region is only required to have a vertical component with respect to the inline axis of the cathode ray tube in order to impart horizontal movement.

Since the color purity adjustment may have to give a large motion, the strip-shaped magnetic member must also be able to generate a sufficiently strong color-purifying magnetic field. Moreover, correction by the color-purifying magnetic field does not give rise to any actual electron beam fogging rate. That is, the three sets of electron beams must all move substantially in the same direction and the same size.

According to the present invention, in the cathode ray tube of a color television receiver, a magnetization apparatus for optimizing color purity by three sets of electron beams is obtained. In this cathode ray tube, a magnetic material is disposed in contact with the neck portion. The magnetizer has at least two conductor loops arranged to be arranged around the neck portion in the vicinity of the magnetic material. Each conductor loop can be activated by a magnetizing current, thereby creating a permanently magnetized region in the magnetic material, creating a color purity magnetic field in the cathode ray tube. This magnetic field achieves an optimum purity of three sets of inline electron beams. The long part of each conductor loop is arranged along the peripheral part of the neck part.

Hereinafter, with reference to the accompanying drawings will be described the present invention in more detail.

In FIG. 1, a magnetizable strip-shaped or seed-type member 20 made of a magnetic material is provided in contact with the neck portion 21 of the cathode ray tube 22. This member 20 is of sufficient length to surround the neck 21, leaving a small gap 23 to prevent the magnetic material from overlapping at the top of the neck. The component of the magnetic material of this member 20 can also be a normal barium ferrite mixed with the rubber | gum or a plastic binder. This member 20 can be fixed to the neck 21 by an adhesive agent or by winding a thin nonmagnetic material tape around it.

Cathode ray tube 22 has three sets of inline electron guns 24, 25 and 26 for generating blue, green and red electron beams. In the figure, the green electron gun is shown along the central axis 53 of the tube. Around the neck portion 21, a raster forming deflecting device 27 including ordinary horizontal and vertical windings is provided. As shown in enlarged cross-sectional view 99 of FIG. 2, all three sets of inline electron beams intersect at the face of the shadow mask 61 and are common to the fluorescent screen 67 deposited on the face plate 63 of the cathode ray tube 22 through a suitable hole 62. When projected onto the three-color phosphors 64, 65, 66, static focusing, that is, center focusing, is obtained.

In order to obtain an appropriate color purity, a permanent magnetization region having an appropriate polarity and strength is formed in the band-shaped magnetic member 20. These regions generate an internal color circulation magnetic field for projecting each of the three sets of inline beams onto each of the color phosphor stripes 64 to 66 as shown in FIG.

In order to make these areas, a magnetizing device 28 is provided around the band-shaped magnetic member 20. The magnetizing device 28 has an annular housing 29 made of a non-magnetic material, the inner surface of which has a set of four conductors 30 to shaped tangentially to the circumferential surface of the neck portion 21 as shown in FIG. 33 is buried. The cross sections of the conductors 30 to 33 may be circular or spherical. Conductors 30 and 31 and conductors 32 and 33 are separated by spacers 97 and 98. The ends of conductors 30 and 33 and the ends of 31 and 32 are connected by interconnect conductors 34 and 35, respectively. The other ends of the conductors 30 and 31 are connected to the terminal conductors 37 and 38, respectively. Terminal conductors 37 and 38 are connected to a magnetizing current source (not shown) with a selectable polarity, magnitude and duration to create a suitable permanent magnetization region for color purification.

When the conductors are connected as described above, two elongated conductor current loops 39 and 40 are formed by these four conductors. Each conductor loop thus has a form extending in a tangential direction with respect to the circumferential surface of the neck portion 21. When the conductor loops 39 and 40 are activated by the peak magnetizing current flowing in the direction indicated by the arrow, the current flows in the direction indicated by the arrow in Fig. 4 within each conductor loop. In FIG. 4, connecting conductors and terminal conductors 34 to 38 are functionally shown with end windings 41 to 44. In FIG.

This magnetizing current forms a magnetized region in the material of the band-shaped magnetic portion 20. These regions generate vertical magnetic lines 45 to 47 perpendicular to the beams 24 to 26 along the inline side 51. These lines of magnetic force generate horizontal forces and movements 48 to 50 to achieve three sets of beam color purity. Color purity mismatch appears on the screen of the cathode ray tube. To obtain the desired beam motion, a current pulse with a suitable peak and direction is applied to terminal conductors 37 and 38.

If the mismatch still occurs, the above operation is repeated until the desired color purity is obtained. The magnetization current pulse supply method to the magnetization device 28, such as stabilizing the magnetic material of the strip-shaped magnetic part 20 and preventing the element of the magnetized material having the magnetized region, has been filed on July 26, 1977. Patent Application No. 819,095 (Korean Patent Application No. 78-2292).

Barium ferrite used as the magnetic material of the twelfth portion has a relative permeability of almost one. Thus, as shown in FIG. 5, the magnetic field lines 52 pass through the material of the band member 20 substantially without being deformed or distorted. By using a sufficiently strong magnetic force line, the same color purified permanent field for obtaining color purity can be imprinted in the member 20 material.

If the long parts of the conductor loops 39 and 40 are along the circumferential surface of the neck 21, and the loop is formed so that the end of the loop is adjacent to the receiving line axis 51, the inner magnetic field 52 is a tintion magnetic field in the inner surface perpendicular to the central axis. That is, as shown in FIG. 5, the magnetic field increases in strength along the deflection line of the center beam. Such a magnetic field is preferably offset in the barrel magnetic field generated in the magnetic member 20 and perpendicular to the central axis 53 and in a plane somewhat separated from the member 20. In this way, movement of substantially the same magnitude can be given to three sets of beams.

As shown in FIG. 6, magnetization regions such as regions 54 and 55 in the vicinity of the vertical center line 60 are involved in the formation of the barrel-shaped magnetic field, while regions near 51 of the inline axis such as 56 to 59 in FIG. Forms a magnetic field. The ends of the elongate conductor loops 39 and 40 shown in FIG. 5 are within about 5 ° from the horizontal inline axis 51, and a large enough magnetization region near the inline axis to form the desired magnetic field in its entirety is pinned. Form. The pincushion shape of the magnetic field can be made stronger by reducing or eliminating the magnetization region in the strip-shaped member 20 near the vertical center line 60, for example, by reducing the width of the conductor loops 39 and 40 near the vertical center line.

In the colorization of certain types of cathode ray tubes, registration correction of about 0.127 mm (± 5 mil) may be required by measuring from the center of the screen to the horizontal direction. Thus, the magnetization device 28 must be able to create a magnetization region in the band-like member 20 that causes this size of motion. It is assumed that most components of the magnetic field in the member 20 are in the tangential tangential direction to the circumferential surface of the neck 21. By generating a sufficiently strong magnetic field, such a large beam motion can be executed.

Here, the magnetic regions 61 and 62 in the strip-shaped member 20 having only radial lines 63 are not included at all, as shown in FIG. Such magnetic lines of force can be made, for example, by placing solenoid coils in the vicinity of regions 61 and 62 so as to flow a current of a suitable polarity. An equivalent bar magnet hole for the thickness d of the strip-shaped site shown in FIG. 8 and its outer radius r is shown in FIG. The distance between poles N and S of bar magnet 61a and between poles N 'and S' of bar magnet 62a is d. This distance is relatively small compared to the radius r, typically about 15.24 mm (about 0.6 inches) and about 1.524 mm (about 60 mils) or less. The magnetic force line 63a that combines the inner poles N and S 'is only slightly larger in relative magnitude than the magnetic force line 63b which combines the external magnetic poles S and N'. Unless the magnetic pole strengths of the rod magnets 61a and 62a are made relatively large, the total magnetic field represented by the magnetic field lines 63 is very small.

In other words, the magnetization current flowing through the solenoid coil generates a certain amount of beam motion, so it must be relatively large to generate sufficient magnetic field strength at the beam position. In magnetizers using solenoid coils, there may be cases where this relatively strong magnetic field required at the beam position cannot be generated.

Furthermore, at some positions along the central axis, the direction of the magnetic field may be reversed, thereby causing the beam's direction of motion to be reversed from the desired direction. This magnetic field reversal occurs when a magnetic force line that combines the S and N 'poles of the magnets 61a and 62a is stronger than the magnetic force line that couples the other poles of these magnets at a predetermined point on the central axis. Thus, a stronger total mother-of-pearl is needed to achieve the desired total movement.

However, considering the band member 20 having a magnetization region having only tangential magnetic lines 65 as shown in FIG. 10, the equivalent bar magnet configuration is made of part of the C-shaped magnet 64a as shown in FIG. . The magnetic poles of the magnet 64a are separated by a relatively large distance, and the corresponding center angle is θ. The total magnetic field 65a is sufficient strength to produce the desired beam movement.

A relatively simple method for generating a magnetic field in the strip member 20, the substantial part of which is a component of the tangential direction, can be shaped to draw conductor loops 39 and 40 tangentially to the circumferential surface of the neck 21. As shown in FIG. 5, the magnetic field in the member 20 has a tangential component such as the component 52a of the magnetic force line 52. Substantial motion relative to beams 24 to 26 can be imparted without having to flow relatively large magnetization currents through loops 39 and 40.

When a stronger magnetic field is obtained without increasing the amplitude of the magnetizing current, it is better to arrange a separate conductor loop in the tangential direction with respect to the neck circle main surface. These loops elongate their long portions so that their ends do not have to approach the end inline side of the loop originally installed. However, the pinion type magnetic field generated thereby becomes smaller correspondingly.

Typical characteristics of the band-shaped magnetic member 20, the cathode ray tube 22 and the magnetization device 28 are as follows.

Band-shaped magnetic element: Length 96.52 mm (3.8 inches), Width 17.15 mm (0.060 inches), Max gap width 2.54 mm (0.100 inches) Material: General tires sold by General Tire and Rubber Company of Evansville, Indiana, USA Barium ferrite mixed in a rubber binder with a BH characteristic down to 1.1 × 10 ⁶ Gauss Ernst, such as tire compound 39900.

Cathode ray tube; 13V inline type, 90 ° deflection angle, using slotted shadow mask, alternate voltage 25kv, electron spacing about 6.76mm (0.26inch), neck diameter about 29.11mm (1.146inch)

Magnetizer: Uses 4 loops formed with angular copper wire of about 1.02mm (0.04 inch), Width about 5.72mm (225mil) along the center axis of the loop: Neck circumference to obtain magnification within 5 ° of the inline axis 4.928mm (1.94 inches) in length, non-ferrule and current required for maximum beam motion for junction compensation, 2800A, magnetization current pulse duration 15μs

Static focusing correction can be performed using, for example, a conventional adjustable magnetic ring member such as described in US Pat. No. 3,725,831. Alternatively, another suitable magnetized region may be formed in the band-shaped magnetic member 20. Magnetization devices that can make these areas are described in US Patent Application No. 819,093 (Korean Patent Application No. 78-2293) filed on July 26, 1977. For some types of cathode ray tubes, the magnetization zone for color purification should be placed in front of the electron gun to minimize scattering of the beam.

Claims (1)

In a cathode ray tube of a color television receiver having a magnetic material disposed adjacent to a neck portion, a magnetization apparatus used for obtaining an appropriate chromaticity by three sets of inline electron beams, wherein the peripheral surface of the neck portion is adjacent to the magnetic material. A conductor device (39, 40) capable of being disposed in and generating a color purity magnetic field to be activated by a magnetizing current to form a permanently magnetized region in the magnetic material to generate an appropriate color purity by the three sets of inline electron beams. And, when the conductor device is activated by the magnetization current, a magnetic field formed in the magnetic material (20), the magnetic field being formed by a component extending mostly in the tangential direction to the circumferential surface of the neck portion.

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