JPH07288831A - Suppression method for undesired electric field - Google Patents

Abstract

PURPOSE:To obtain an inexpensive cathode ray tube display device with simple structure in which an undesired electric field with a horizontal deflection period leaked from the cathode ray tube display device is reduced with a simple means. CONSTITUTION:The cathode ray tube display device is provided with a winding 3 being a negative pulse generating means with a horizontal deflection period H and a negative pulse S generated from the negative pulse generating winding 3 is superimposed on a high voltage power supply HV via a smoothing capacitor 4. Thus, a ripple P with a horizontal deflection period H included in the high voltage power supply HV is cancelled and an undesired electric field by the horizontal deflection period H generated from a deflection yoke or the like is cancelled to reduce the undesired electric field leaked from the cathode ray tube display device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for suppressing an unnecessary alternating electric field generated from a deflection yoke device, a flyback transformer or the like in a cathode ray tube display device using a cathode ray tube, and more particularly to a cathode ray tube display device. The present invention relates to a method for suppressing an unnecessary electric field that can reduce adverse effects on an electronic device and a human being in the vicinity due to an electric field of an extremely low frequency (5 Hz to 400 kHz) leaking from a device.

[0002]

2. Description of the Related Art In recent years, unnecessary electromagnetic fields leaking from cathode ray tube display devices and the like, which are widely used as computer terminals, have come to be regarded as a problem. The reason is that these unnecessary electromagnetic fields may cause radio interference to the electronic devices around them, and may adversely affect humans or animals in terms of health. Because it is done.

Therefore, in order to reduce damages and adverse effects on electronic devices and humans due to these unnecessary electromagnetic fields, for example, an alternating electric field (A) according to the Swedish MPR-II standard is used.
EF) standards are defined. And, according to this standard, it is recommended to suppress the unnecessary electric field leaking from the cathode ray tube display device to a certain amount or less. Specifically, it is recommended that the value of the electric field strength measured 0.5 m away from the tube surface of the cathode ray tube display device is 2.5 V / m or less.

[0004]

In order to satisfy the above-mentioned MPR-II standard, in the cathode ray tube display device, a horizontal deflection frequency pulse generated from a deflection yoke device or a flyback transformer or a cathode ray tube is used. It is necessary to prevent or reduce unnecessary leakage of an electromagnetic field caused by a high-voltage power supply or the like that includes ripples of the horizontal deflection period supplied to the anode electrode. As means for preventing and reducing leakage of unnecessary electromagnetic fields, conventionally, means for covering the entire cabinet of the cathode ray tube display device with a metal member, and glass plates provided with a conductive mesh on the cathode ray tube surface have been used. A means for electrically connecting the conductive mesh with the cabinet of the cathode ray tube display device is provided.

However, in the former of these conventional methods, it is impossible to cover the entire surface of the cathode ray tube display device having the visible display portion with a metal member, while on the other hand, the latter glass plate provided with a conductive mesh. In the case of using a cathode ray tube display device, the structure of the cathode ray tube display device becomes complicated and the cathode ray tube display device itself becomes expensive, and it is difficult to obtain a cathode ray tube display device satisfying the MPR-II standard. Met.

An object of the present invention is to provide a cathode ray tube display device which can solve these problems by a simple means, has a simple structure and is inexpensive.

[0007]

A cathode ray tube display device is provided with negative pulse generating means of a horizontal deflection period, and a negative pulse generated from the negative pulse generating means is supplied to a high voltage of the cathode ray tube display device through a smoothing capacitor. By superimposing it on the power supply, the ripple of the high-voltage power supply is canceled and the unnecessary electric field due to the pulse of the horizontal deflection cycle is canceled, and the unnecessary electric field leaking from the cathode ray tube display device is reduced.

The negative pulse generating means may be composed of a negative pulse generating winding arranged in a flyback transformer or may be configured in a circuit manner, and the negative pulse generating means includes a pulse voltage adjusting means, or It is more effective if a phase adjusting means is provided.

[0009]

The negative pulse generating means of the horizontal deflection period is arranged in the cathode ray tube display device, and the negative pulse generated from the negative pulse generating means is superimposed on the high voltage power source of the cathode ray tube display device through the smoothing capacitor. As a result, the ripples of the horizontal deflection cycle included in the high voltage power source are canceled out, and the unnecessary electric field is reduced. Further, an electric field that cancels an unnecessary electric field due to a pulse from the deflection yoke or the like is generated from the negative pulse, and an unnecessary electric field leaking from the cathode ray tube display device is reduced. Particularly, a cathode ray tube display by an ultra-low frequency electric field is displayed. The influence on the electronic devices and people around the device is greatly reduced.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to FIGS.
FIG. 1 is a circuit diagram for explaining a method of suppressing an unnecessary electric field according to the present invention, and FIGS. 2A and 2B are waveform diagrams showing a ripple and a negative pulse included in a high voltage power source, respectively.

In the figure, reference numeral 2 is a flyback transformer, and the flyback transformer 2 has lead terminals A and B of a primary winding M1, one lead terminal C of a secondary winding M2, and negative pulse generating means. One lead terminal D of the pulse generation winding 3 and a smoothing capacitor 4 (3, 0
An anode terminal E for supplying the high voltage power source smoothed by the smoothing capacitor 4 to the anode electrode of the cathode ray tube display device is provided. Reference numeral 5 is a high-voltage rectifier diode, and 6 is an internal resistance.

The lead terminals A, B, C, D,
Each of E, the smoothing capacitor 4, and the high-voltage rectifying diode 5 is integrally molded with an insulating resin to form a flyback transformer 2. In addition, the negative pulse generating means 3 is wound around the core of the flyback transformer 2.
It is composed of a turn winding and generates a negative pulse S having a horizontal deflection period with a waveform as shown in FIG.

In the flyback transformer 2 thus constructed, the output from the secondary winding is smoothed by the smoothing circuit composed of the high voltage rectifying diode 5, the internal resistor 6 and the high voltage smoothing capacitor 4, and at the same time, the smoothing capacitor 4 A negative pulse S having a horizontal deflection period H is superimposed via the.

Therefore, when the high-voltage power supply HV supplied to the anode electrode of the cathode ray tube display device contains a ripple P having a waveform as shown in FIG.
Are canceled by the negative pulse S, so that the amplitude changes from P1 to T1, for example. As a result, the high voltage power supply H
Leakage of the unnecessary electric field due to the ripple P included in V is reduced similarly to the change of the amplitude of the ripple P.

On the other hand, since the negative pulse S generates an electric field for canceling the unnecessary electric field due to the horizontal deflection period pulse generated from the deflection yoke or the like, the unnecessary electric field leaking from the cathode ray tube display device is reduced. As a result,
The electric field strength, which was 2.7 V / m in the conventional method, is reduced to 1.8 V / m in the embodiment of the present invention.
We were able to fully satisfy the standard.

As described above, according to the present invention, the unnecessary electric field leaking from the cathode ray tube display device is reduced not only when the high-voltage power supply includes ripples but also when the high-voltage power supply does not include ripples. It has become possible to

If the voltage value or the phase of the negative pulse of the horizontal deflection cycle generated from the negative pulse generating winding 3 can be adjusted by the variable resistor, the ripple P contained in the high voltage power supply HV can be completely eliminated. Can be offset. Furthermore, it goes without saying that the negative pulse generating means can be configured using a known circuit.

[0018]

According to the present invention, the negative pulse generating means of the horizontal deflection period is arranged in the cathode ray tube display device, and the negative pulse generated in this negative pulse generating means is passed through the smoothing capacitor to the cathode ray tube display device. By the simple means of superimposing it on the anode electrode, it becomes possible to reduce the unnecessary electric field leaking from the cathode ray tube display device, which was impossible by the conventional method. As a result, in particular, a cathode ray tube display device having a simple structure and satisfying the MPR-II standard provided for an extremely low frequency electric field can be obtained, and its practical effect is great.

[Brief description of drawings]

FIG. 1 is a circuit diagram for explaining a method of suppressing an unnecessary electric field according to the present invention.

FIG. 2 shows a ripple and a negative pulse included in a high-voltage power supply, FIG. 2 (a) is a waveform diagram showing the ripple of the high-voltage power supply and a ripple canceled by the pulse, and FIG. 2 (b) is a negative pulse. It is a waveform diagram shown.

[Explanation of symbols]

 2 Flyback transformer 3 Negative pulse generating means 4 Smoothing capacitor 5 High voltage rectifier diode 6 Internal resistance M1 Flyback transformer primary winding M2 Flyback transformer secondary winding A, B Primary winding lead terminal C Secondary winding Lead terminal D Negative pulse generating winding lead terminal E Anode terminal P, T Ripple S Negative pulse HV High voltage power supply

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location // H05K 9/00 Z

Claims (3)

[Claims] 1. A method for suppressing an unnecessary electric field of a horizontal deflection period leaking from a cathode ray tube display device, wherein the cathode ray tube display device is provided with negative pulse generating means of a horizontal deflection period,
Suppression of an unnecessary electric field, characterized in that a negative pulse generated from the negative pulse generating means is superimposed on a high voltage power supply of the cathode ray tube display device through a smoothing capacitor to reduce an unnecessary electric field leaking from the cathode ray tube display device. Method. 2. The negative pulse generating means is a winding arranged in a flyback transformer.
The method for suppressing an unnecessary electric field described. 3. The method for suppressing an unnecessary electric field according to claim 1, wherein the negative pulse generating means is provided with pulse voltage adjusting means or phase adjusting means.