JPH0815339B2 - Magnetic transfer method of cathode ray tube - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a magnetic transfer method for manufacturing cathode ray tubes for foreign countries having different geomagnetic directions, and more particularly to a magnetic transfer method of a color selection mechanism.

[Outline of Invention]

The present invention is a magnetic transfer method for manufacturing cathode ray tubes for foreign countries having different geomagnetism directions, in which a pair of transfer coils facing each other is arranged outside the cathode ray tube so as to follow the curved surface of the funnel, This transfer coil moves from the funnel side to the panel side, and again applies a transfer magnetic flux to the funnel side to demagnetize by giving a damping magnetic field in the tube axis direction, so that the cathode ray tube can be installed even if an internal magnetic shield plate is provided. With this, it is possible to appropriately perform magnetic transfer.

[Conventional technology]

As shown in Fig. 7, in order to correct the mislanding due to the geomagnetic field in a color cathode ray tube (1) manufactured in Japan, which is different from the direction of the domestic geomagnetic field, such as Australia, a magnetic field called a mini Helmholtz coil (MHC) is used. Using the transfer coil (2), the same transfer magnetic flux (10) as that of geomagnetism in Australia is applied in the vertical direction so that it is parallel to the panel surface, and is transferred parallel to the panel surface by the twin coil degauss (TCD) (3). An alternating damping magnetic field (20) is applied in the direction orthogonal to the magnetic flux to demagnetize. For example, the vertical geomagnetism (BV) in Japan in the northern hemisphere is 0.35 gauss, whereas the vertical geomagnetism in Australia in the southern hemisphere is -0.55 gauss.

[Problems to be solved by the invention]

As shown in Figs. 7 and 8, conventional transfer magnetic flux (10)
Are uniformly and parallel to the panel (4) surface of the cathode ray tube (1). However, in the method of applying a uniform transfer magnetic field, in the case of a tube type in which the internal magnetic shield (IMS) (5) is provided in the color cathode ray tube (1) as shown in FIG. 9, the internal magnetic shield (5) There was a problem that the magnetic transfer of the portion surrounded by could not be performed properly. That is, since the portion surrounded by the internal magnetic shield (5) also shields the transfer magnetic flux, magnetic transfer is weakened, and the shaded portion (6) near the x-axis end is weakened, but the x-axis end is still weakened. The magnetic transfer amount in the vicinity is larger than the appropriate magnetic transfer amount. Looking at the force received by the electron beam in the actual operating state of the color cathode ray tube, the electron beams B _-1 , B ₁ scanning both ends of the x-axis
The forces F _-1 , F ₁ received (see FIG. 10) are larger than the force F ₀ received by the electron beam B ₀ (see FIG. 10) scanning the center.

That is, as shown in FIG. 11, the current direction flows from the fluorescent surface side to the electron gun side, and the magnitude of the component in the Z direction (tube axis direction) is i _z0 (corresponding to beam B ₀ ) in the center. , Both ends i _x-1 ,
If i _x1 (corresponding to beams B _-1 , B ₁ ), then i _z0 > i _z-1 =
i _z1 . The current at both ends is the x component current i _x-1 ≈i _x1
Therefore, when a Y direction magnetic field (vertical magnetic field Bv) is applied, a force (F) is generated. Here, when acting in the direction of accelerating the current, the electron beam receives a force in the direction toward the center of the cathode ray tube, and when acting in the direction of decelerating the current, the electron beam is directed toward the outside of the cathode ray tube. Receive power. Now, considering the internal magnetic shield (5), the force (F) is represented by a vector as shown in FIG. (21) shows the density and coarse state of the magnetic flux due to the internal magnetic shield in a uniform magnetic field. The solid arrow (→) is the force due to the current i _z , and the dashed arrow () is the force due to i _x .

Therefore, when demagnetized and magnetically transferred in this state, the relationship of the force (F) in the vertical magnetic field is F ₀ <F ₋₁ ≈F ₁ , and the ideal relationship F ₀ ≈F ₋₁ ≈F ₁ is not obtained.

The cathode ray tube (1) thus equipped with the internal magnetic shield
When magnetic transfer is performed by the conventional method, the magnetic transfer of the part surrounded by the internal magnetic shield cannot be performed properly, the balance with other parts is poor, and mislanding due to geomagnetism cannot be sufficiently prevented. , Could not be used as a receiver. In addition, in FIG. 7 to FIG.
(7) is a funnel, (8) is a neck portion, (9) is an anode button, and (10) is magnetic flux.

The present invention provides a magnetic transfer method for a cathode ray tube which can solve the above problems.

[Means for solving problems]

In the present invention, when magnetic transfer is performed to a cathode ray tube (1) for overseas having different geomagnetic directions, that is, a cathode ray tube having an internal magnetic shield, a funnel (7) is provided outside the cathode ray tube (1). Facing each other along the curved surface of
Arrange a set of transfer coils (11), and transfer coils (11)
Thus, the demagnetization is performed by applying the damping magnetic field in the tube axis direction while applying the transfer magnetic field from the funnel (7) side to the panel (4) side and again toward the funnel (7) side.

In this case, the transfer magnetic flux is increased in the central portion (14) of the panel (4) and further reduced in both end portions (16) in the x-axis direction so that the roughness and the density of the transferred magnetic flux are more remarkable than in the conventional case.

[Action]

According to the present invention, with respect to the transfer magnetism, the conventional magnetic field is applied uniformly and parallel to the surface of the panel (4), and it is close to being perpendicular to the surface of the funnel (7) and the internal magnetic shield (5).
The panel (4) is designed so that it fits inside.
Since the central part (14) is increased and the both end parts (16) are reduced to make the density state more conspicuous than before, the force (F) relationship received by the electron beam at the both end parts and the central part as described above. Can be set to F ₀ ≉F _-1 ≉F _1, and magnetic transfer to a color selection mechanism (not shown) can be almost ideally performed in a cathode ray tube for overseas use equipped with an internal magnetic shield.

〔Example〕

An embodiment of the present invention will be described with reference to FIGS.

In this embodiment, as a coil for applying a transfer magnetic flux, an elliptical transfer coil (11) having a major diameter of 330 mm and a minor axis of 130 mm is formed by winding a conductor wire having a diameter of 055 mm 150 times as shown in FIG. To use. Then, as shown in FIGS. 1 and 2, the transfer coil (11) is arranged outside the cathode ray tube (1). That is, one set of transfer coils (11) are arranged so as to face each other near the central portion of the outer side surface of the panel (4) on the long side.
Bend at an appropriate angle to fit the curved surface of the funnel (7). The set of transfer coils (11) is connected to a common power source (12). This transfer coil (11) is shown in FIG.
The relationship of the magnetomotive force [AT] corresponding to the transfer landing amount when using is shown. Therefore, based on this graph, the magnetomotive force is determined according to the transfer landing amount in a specific area of the Southern Hemisphere. As the coil for degaussing, a rectangular triac degauss coil (TDC) (13) arranged around the cathode ray tube (1) is used.

In order to perform magnetic transfer, first, the power supply (12) of the transfer coil (11) is turned on as shown in FIG. As a result, as shown in Fig. 3, the transfer magnetic flux (10), which is the same as the geomagnetism in a specific foreign country, for example, Australia in the Southern Hemisphere, is transferred from the funnel (7) side to the panel (4) side, and the funnel (7 ) Side, and with a proper magnetic flux distribution such that the x-axis end portion (16) of the color selection mechanism is small and the central portion (14) is large. In this case, by adjusting the major axis and the minor axis of the elliptical transfer coil (11), it is possible to correct the density of the transfer magnetic flux (10) at the end portion and the central portion. That is, even if the internal magnetic shield (5) is provided as in the cathode ray tube (1) according to this embodiment, the transfer magnetic flux (10) can be transferred to the internal magnetic shield (5) in a proper density state. It is possible to wrap around and magnetize a color selection mechanism (not shown). Next, with the transfer magnetic flux applied in this way, a 147.8 mH TRIAC degauss coil (1
Turn on the power supply of 3) and first apply 6.4 A of alternating current to gradually attenuate and degauss. (15) is the envelope of the degaussing current. The AC damping magnetic field generated by the triac degauss coil (13) is applied in the tube axis direction of the panel (4) surface and the neck portion (8) direction. Then, after the degaussing is completed, the power supply (12) of the transfer coil (11) is turned off.

As a result, it is possible to perform proper magnetic transfer so that the end portion of the x-axis becomes weaker than in the conventional case with respect to the color selection mechanism of the color cathode ray tube having the internal magnetic shield. Therefore, it is possible to easily manufacture a cathode ray tube for overseas use from a completed cathode ray tube of domestic specifications without changing the process conditions.

〔The invention's effect〕

According to the present invention, even in a cathode ray tube having an internal magnetic shield, since the transfer magnetic flux also enters the internal magnetic shield, magnetic transfer can be performed almost ideally. Also,
Since a demagnetizing field is applied in the tube axis direction to degauss, it is possible to degauss without being affected by the internal magnetic shield. Since the magnetic transfer according to the present invention can be performed on a cathode ray tube that has been completed in the conventional domestic specifications, the cathode ray tube for overseas can be easily manufactured. This finally transferred magnetism cannot be removed even by a hand degauss used for service or the like.

[Brief description of drawings]

1 is a side view of the embodiment, FIG. 2 is a plan view of the embodiment, FIG. 3 is a bottom view of the embodiment, FIG. 4 is a magnetic transfer characteristic view, and FIG.
6 is a plan view of the transfer coil, FIG. 6 is a characteristic diagram of magnetomotive force, FIG. 7 is a plan view of a conventional example, FIG. 8 is a perspective view of a conventional example, and FIG.
FIG. 10 is a plan view of a conventional example, FIG. 10 is a view showing the position of an electron beam as seen from the front of a cathode ray tube, FIG. 11 is a view showing a current direction at each electron beam position, and FIG. 12 is a view in a magnetic field. It is a figure which shows the force (F) which each electron beam receives. (1) is a cathode ray tube, (4) is a panel, (5) is an internal magnetic shield, (7) is a funnel, (8) is a neck part,
(10) is a transfer magnetic flux, (11) is a transfer coil, (14) is a central portion of the panel, (16) is an end portion of the panel, and (20) is an attenuation magnetic field for demagnetization.

Claims (1)

[Claims] 1. A set of transfer coils facing each other along the curved surface of the funnel is arranged outside the cathode ray tube, and a transfer magnetic field is applied from the funnel side to the panel side and again to the funnel side by the transfer coils. A magnetic transfer method for a cathode ray tube, characterized in that a demagnetizing field is applied in the tube axis direction to demagnetize the tube.