JPH0646142Y2 - Leakage magnetic flux reduction device - Google Patents

Description

The present invention relates to a leakage flux reducing device, and more particularly to a leakage flux reducing device for reducing leakage flux generated by a deflection coil of a CRT (cathode ray tube) display device. .

(Prior Art) A display device such as a display using a CRT (Cathod Ray Tube) uses a magnetic field generated by a deflection coil or the like as a method of deflecting an electron beam.

For this reason, in the display device using the CRT, the device is covered with a metal plate so that the magnetic flux generated by the deflection coil or the like does not leak from the device and interfere with other devices.

(Problems to be solved by the invention) However, in the conventional leakage magnetic flux reducing device, since the leakage magnetic flux is shielded only by the metal plate, since the display device such as the TV and the display is a display device, even the display surface thereof is not provided. There is a problem that magnetic flux leaks from the display surface because it cannot be covered with a metal plate.

The present invention has been made in view of the above points, and an object of the present invention is to provide a leakage flux reducing device that reduces leakage of magnetic flux to the display surface without providing any obstacle on the display surface.

(Means for Solving the Problems) The present invention has been made to solve the above problems, in which an electron beam is deflected by a deflection coil to hit a fluorescent display surface, and the fluorescent display surface is caused to emit light for display. In a leakage flux reducing device of a display device, an electric wire which is arranged around the fluorescent display surface and which is supplied with current so that a magnetic flux in a direction opposite to the direction of the magnetic flux leaking from the deflection coil is generated in the periphery, It is an object of the present invention to provide a leakage flux reducing device, which is connected in parallel with an electric wire and is provided with an inductance for adjusting a current flowing through the electric wire by changing an inductance value.

(Embodiment) FIG. 1 shows a perspective view of an embodiment of the present invention. 1 is CRT,
Reference numeral 2 represents a deflection coil, and 3a, 3b and L ₁ respectively represent a cancel magnetic flux generating electric wire, which is a main part of the present invention, and a variable inductance or a fixed inductance connected in parallel to the cancel magnetic flux generating electric wires 3a, 3b. FIG. 2 is an electrical equivalent circuit of the device according to the present invention. As shown in FIG.
The deflection circuit unit 10 having the flyback transformer 11 is connected via a deflection coil 2 to a parallel circuit of the cancel magnetic flux generating wires 3a and 3b and the variable inductance L ₁ .

The horizontal deflection coil oscillates the electron beam in the horizontal direction, so that a magnetic flux is generated in the vertical direction orthogonal to the scanning direction of the electron beam. Therefore, horizontal deflection coils are provided above and below the electron gun 4. Therefore, the leakage magnetic flux generated by the horizontal deflection coil is generated in the directions shown in FIGS. 3 and 4, for example.

The solid lines in FIGS. 3 and 4 show the direction of the leakage magnetic flux generated by the horizontal deflection coil. Since a signal with a relatively high frequency is supplied to this horizontal deflection coil, it is generated by the horizontal deflection coil. The magnetic flux leaking from a device in a magnetic field is likely to interfere with other devices, and regulations are particularly strict. Therefore, in this embodiment, the device is configured to reduce the leakage magnetic flux generated by the horizontal deflection coil.

The electric wire 3a is arranged so as to wind the upper half around the display surface 5, the electric wire 3b is arranged so as to wind the lower half, and a horizontal deflection current is supplied, for example, in a direction indicated by an arrow in FIG. It

The deflection coil 2 is provided near the electron gun 4 and deflects the electron beam. A horizontal deflection current is supplied to the deflection coil 2 from a deflection circuit. At this time, the signal from the deflection circuit is supplied to the deflection coil 2 and the magnetic flux generating wire 3
It is also supplied to the parallel circuit of a and 3b and the variable inductance L _1, and operates in synchronization with the deflection coil 2.

FIG. 3 is the surface of the magnetic flux generated by the horizontal deflection coil and the cancel magnetic flux generation wire as seen from the rear surface of the CRT, the broken line indicates the magnetic flux generated by the wires 3a and 3b, and the solid line indicates the magnetic flux generated by the deflection coil 2. . As shown in FIG. 3, the magnetic flux generated in the deflection coil 2 is canceled by the magnetic flux generated in the electric wires 3a and 3b.

FIG. 4 is a cross-sectional side view of the CRT of the magnetic flux generated in the horizontal deflection coil and the cancel magnetic flux generating electric wire. As in FIG. 3, the broken line arrow indicates the magnetic flux generated by the electric wires 3a and 3b, and the solid line arrow indicates the deflection coil 2. Is the magnetic flux generated by. As shown in FIG. 4, the magnetic flux generated in the deflection coil 2 is canceled by the magnetic flux generated in the electric wires 3a and 3b.

The leakage magnetic field from the deflection coil changes depending on the shape of the device and the strength of the deflection current, but in the present invention, by adjusting the inductance L ₁ and changing the inductance value, it flows to the cancel magnetic flux generation wires 3a, 3b. Since the current can be changed, it is possible to accurately balance the cancellation with the leakage magnetic flux.

In the above embodiment, the variable inductance L ₁ is used as the inductance, but the optimum one may be selected from a plurality of fixed inductances.

(Effect of the Invention) As described above, according to the present invention, an electric wire is arranged around the display surface, the electric wire and the inductance are connected in parallel, and the current flowing through the electric wire is changed by changing the value of the inductance. Since it is possible to adjust it, it is possible to generate the optimum canceling magnetic flux and accurately cancel the leakage magnetic flux generated by the deflection coil.
It has the features that the leakage flux from the CRT display surface can be reduced without placing any obstacles on the front surface of T, and the interference with other devices can be reduced.

[Brief description of drawings]

FIG. 1 is a perspective view of an embodiment of the present invention, FIG. 2 is an electrical equivalent circuit of the device according to the present invention, FIG. 3 is a rear view of a CRT of an embodiment of the present invention, and FIG. FIG. 3 is a side sectional view of a CRT according to an embodiment of the present invention. 1 ... CRT, 2 ... deflection coils, 3a, 3b ... wire, 4 ... electron beam, 5 ... display surface 10 ... deflection circuit, L ₁ ... variable inductance.

Claims (1)

[Scope of utility model registration request] 1. A leakage flux reducing apparatus for a display device, wherein an electron beam is deflected by a deflection coil to be applied to a fluorescent display surface, and the fluorescent display surface is caused to emit light so as to perform display. An electric wire to which a current is supplied so that a magnetic flux in the direction opposite to the direction of the magnetic flux leaking from the deflection coil is generated in the surroundings, and a current that flows in the electric wire that is connected in parallel with the electric wire and changes the inductance value. An apparatus for reducing leakage flux, characterized by being provided with an adjusting inductance.