JP2001119645A - Leakage electric field canceller for cathode-ray tube device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a leakage electric field canceller for cathode-ray tube that can shield electric field radiation more simply and economically than a conventional method can. SOLUTION: This leakage electric field canceller for cathode-ray tube is provided with a pulse voltage-generating circuit 29 that generates a cancellation pulse voltage to cancel a leakage electric field emitted from a flyback transformer 14 and an antenna lead wire 30, to which the cancellation pulse voltage is applied. The antenna lead wire is placed in the vicinity of a high-voltage wire 25 that connects an anode terminal 10 of the cathode-ray tube to the flyback transformer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for canceling a leakage electric field of a cathode ray tube, and more particularly to a device for canceling a leakage electric field radiated from a flyback transformer.

[0002]

2. Description of the Related Art Generally, as shown in FIG. 3, in a cathode ray tube device, an electron beam emitted from an electron gun 3 provided in a neck 2 of a funnel 1 is applied to a deflection yoke 4 mounted outside the funnel 1. The screen is formed to display an image by horizontally and vertically scanning the phosphor screen 6 provided on the inner surface of the panel 5 by being deflected by the generated magnetic field. In particular, in the color cathode ray tube device, a shadow mask 8 is arranged so as to approach and face the phosphor screen 6, and the shadow mask 8 sorts three electron beams emitted from the electron gun 3 to separate the phosphor screen 6. It is formed in a structure for displaying a color image by being incident on the three-color phosphor layer to be constituted.

In such a cathode ray tube device, in order to display a high-luminance and high-resolution image on the phosphor screen 6, an anode terminal 10 provided on a large diameter portion of the funnel 1 is provided.
, A high voltage is applied to the final acceleration electrode of the electron gun 3, the phosphor screen 6, and the shadow mask 8.
Therefore, an electromagnetic wave is generated from such a cathode ray tube device.

[0004] Therefore, there is a concern that the above-mentioned cathode ray tube device may affect the human body due to electromagnetic waves leaking out of the device. In particular, for display devices used in computer terminals that have been increasingly used in recent years, since operations are performed close to the image display surface, measures to reduce leakage of electromagnetic waves in consideration of the effect on the human body have been taken. Is underway.

As shown in FIG. 4, the main sources of electromagnetic waves from the above-mentioned cathode ray tube device are a deflection yoke 4 mounted on the cathode ray tube, a cathode ray tube device 12 provided with the deflection yoke 4, and a bezel 13. Circuit components for supplying a high voltage and a high current, such as a flyback transformer 14 and a power supply transformer in the power supply circuit 15 incorporated in the power supply circuit 15.

The electromagnetic waves generated from the deflection yoke 4 and the circuit components include magnetic field radiation and electric field radiation, respectively. Among them, the magnetic field radiation is reduced by reducing the degree of leakage from each component or by providing a canceling means. However, although it is known that electric field radiation can be achieved by shielding the entire display device with a metal member, the image display surface cannot be covered with a metal member due to its structure. For this reason, conventionally, a method has been practiced in which the image display surface is covered with a conductive film 17 having excellent conductivity, and a metal plate or an antenna lead wire is stretched around the bezel 13 to apply a pulse voltage of the opposite polarity. I have.

[0007]

As described above, conventionally,
To shield electric field radiation from the cathode ray tube device, a method of covering the image display surface with a conductive film having excellent conductivity and applying a pulse voltage of the opposite polarity by stretching a metal plate or an antenna lead wire in the bezel is implemented. ing.

[0008] However, such a shielding method has a problem that the structure is complicated and expensive. The present invention has been made in view of the above problems, and has as its object to provide a leakage electric field canceling device for a cathode ray tube device, which can shield electric field radiation easily and inexpensively as compared with the conventional method.

[0009]

An anode terminal of a cathode ray tube and a flyback transformer are connected by a high voltage line, and a leakage electric field from a cathode ray tube device for applying a high voltage from the flyback transformer to an anode terminal is shielded. In a leakage electric field canceling device of a cathode ray tube device, a pulse voltage generating circuit that generates a canceling pulse voltage that cancels a leakage electric field radiated from a flyback transformer, and an antenna lead wire to which the canceling pulse voltage is applied, The antenna lead wire was provided near the high voltage wire.

Further, the antenna lead wire is fixed to a high voltage wire.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an overall configuration of a system including a leakage electric field canceling device of a cathode ray tube device, which is one embodiment of the present invention. This system includes a cathode ray tube device 1 incorporated in a bezel 13.
2, a power supply circuit 15 for supplying a predetermined voltage to each member constituting the cathode ray tube, a video circuit 20 for supplying a video signal to the cathode of the cathode ray tube, and an anode terminal 10 of the cathode ray tube.
Transformer 14 for supplying a high voltage to the mirror, and a deflection circuit 21 for supplying a deflection current to the horizontal deflection coil and the vertical deflection coil of the deflection yoke 4 mounted on the cathode ray tube.
And so on.

Further, in this embodiment, in addition to the electric circuit for driving the cathode ray tube device 12, a leakage electric field canceling device 23 for canceling a leakage electric field radiated from the flyback transformer 14 is provided.

As shown in FIG. 2, the leakage electric field canceling device 23 includes a leakage electric field pulse radiated from the flyback transformer 14 to a high voltage line 25 connecting the anode terminal provided on the cathode ray tube and the flyback transformer 14. 26, and an in-phase opposite electric field pulse 28 for canceling the leakage electric field pulse 26 radiated from the flyback transformer 14 based on the output from the detection circuit unit 27 for detecting the electric field. The canceling pulse generating circuit unit 29 and the canceling pulse generating circuit unit 2
9 and an antenna lead 30 (see FIG. 1) for radiating the reverse electric field pulse 28 generated in FIG. The antenna lead wire 30 is wound around the high voltage wire 16 in a coil shape and fixed.

The leakage electric field canceling device 23 is constituted as described above, and the leakage electric field pulse 26 radiated from the flyback transformer 14 is detected by the detection circuit unit 27,
When the opposite electric field pulse 28 of the same phase generated by the canceling pulse generation circuit unit 29 is radiated from the antenna lead wire 30 wound around the high voltage wire 25 by the detection, a metal plate or an antenna lead The radiation of the leaked electric field can be shielded with a simple and inexpensive configuration without having to stretch the wires. In addition, a leakage electric field caused by a fluctuation in the potential of the high voltage supplied from the flyback transformer 14 to the anode terminal 10 can be almost completely shielded.

[0016]

According to the above-described configuration, the leakage electric field leaking out of the cathode ray tube device can be reduced with a simple and inexpensive configuration without the metal plate or the antenna lead wire extending around the bezel as in the related art. Radiation can be shielded.
In addition, a leakage electric field caused by a fluctuation in the potential of a high voltage supplied from the flyback transformer to the anode terminal can be almost completely shielded.

[Brief description of the drawings]

FIG. 1 is a diagram showing an entire system including a leakage electric field canceling device of a cathode ray tube device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of the leakage electric field canceling device.

FIG. 3 is a diagram showing a configuration of a color cathode ray tube device.

FIG. 4 is a diagram for explaining main sources of electromagnetic waves from the cathode ray tube device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Anode terminal 12 ... Cathode tube device 14 ... Flyback transformer 23 ... Leakage electric field canceller 25 ... High voltage wire 29 ... Cancelling pulse generation circuit unit 30 ... Antenna lead wire

Claims (2)

[Claims] 1. A cathode ray tube device for connecting an anode terminal of a cathode ray tube and a flyback transformer with a high voltage line and shielding a leakage electric field from a cathode ray tube device for applying a high voltage from the flyback transformer to the anode terminal. A leakage voltage canceling device, comprising: a pulse voltage generation circuit that generates a cancellation pulse voltage for canceling a leakage electric field radiated from the flyback transformer; and an antenna lead wire to which the cancellation pulse voltage is applied. A leakage electric field canceling device for a cathode ray tube device, wherein a lead wire is provided near the high voltage wire. 2. The leakage electric field canceling device for a cathode ray tube device according to claim 1, wherein the antenna lead wire is fixed to the high voltage wire.