JP3501589B2 - Cathode ray tube - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode ray tube used for TV receivers, display monitors and the like.

[0002]

2. Description of the Related Art A conventional cathode ray tube is disclosed in Japanese Patent Laid-Open No. 7-3.
The one described in Japanese Patent No. 35144 is known. According to this conventional technique, in order to suppress the leakage electric field generated from the cathode ray tube, a compensation coil for inducing an electric field of opposite polarity is provided. The compensation coil is formed by winding a coil, one end of which is grounded and the other end of which is open, around a circular cylindrical base larger than the outer diameter of the neck of the cathode ray tube, and this is called an open electrode. The open electrode is attached to the neck.

[0003]

In the cathode ray tube of the prior art, when a high voltage flyback pulse is applied to the horizontal deflection coil arranged around the neck portion of the cathode ray tube (CRT) at a predetermined cycle. , A leakage electric field is generated toward the front of the CRT. The frequency of this leakage electric field is 15 KH
The frequency band is from z to 100 KHz, which is synchronized with the horizontal scanning frequency, and is included in the frequency band of 2 KHz to 400 KHz (hereinafter referred to as VLF frequency band, and the leakage electric field in this frequency band is referred to as VLF leakage electric field).

The VLF leakage electric field is generated in the front part of the CRT. Therefore, it is difficult to shield this, which is a problem in terms of safety measures. Some countries have safety standards in place to regulate VLF leakage fields. For example, according to the Swedish safety standard TCO, VLF is measured 30 cm ahead of the CRT surface of the CRT display body.
It is said that the strength of the leakage electric field must be a value smaller than 1.0 V / m. However, the CR of the prior art in which a compensation coil for suppressing a leakage electric field is simply provided at the neck portion
At T, the VLF leakage electric field from the CRT surface was large and it was difficult to satisfy this standard.

[0005]

A cathode ray tube of the present invention comprises a glass bulb formed by sequentially forming a front panel, a cone portion and a neck portion, and a glass bulb having a horizontal surface on an outer peripheral surface of the cone portion and the neck portion. It includes a cylindrical deflector having deflection coils and vertical deflection coils, and a complement <br/> amortization coil disposed between the outer surface and the cylindrical inner peripheral surface of the deflection device of said glass bulb, said Compensation coil spiral winding
And the outer peripheral surface of the spiral portion was surrounded by an insulator.
One end is grounded and the other end is open.
The curved surface is the magnetic field of the horizontal deflection coil or the vertical deflection coil
Deflection yoke and cathode ray tube so as to substantially intersect the magnetic field of
It is arranged so as to be sandwiched between, on the compensation coil
A voltage of opposite polarity synchronized with the deflection voltage waveform of the deflection device
Opposite to the leakage electric field generated by the deflection device.
Generated by the deflection device by creating a polar electric field
It is characterized by suppressing a leakage electric field . A leakage electric field generated by the deflecting device is generated in the compensating coil by generating a reverse electric field having a polarity opposite to that of the leakage electric field generated by the deflecting device by inducing a reverse polarity voltage synchronized with the deflection voltage waveform of the deflecting device. Suppress.

In the compensation coil, the winding is formed in a spiral shape, and the outer peripheral surface of the spiral portion is surrounded by an insulator, and the spiral surface is a magnetic field of a horizontal deflection coil or a vertical deflection coil. Of the winding, and one end of the winding is grounded and the other end is open. The compensating coil includes a first compensating coil and a second compensating coil that are opposed to each other with a glass bulb interposed therebetween. The first compensating coil and the second compensating coil are connected in series, and the compensating coil is connected in series. One end of the compensation coil is installed and the other end is open. By providing two compensating coils, the induced voltage becomes larger than that when only one compensating coil is provided, and the effect of suppressing the leakage electric field generated by the deflecting device becomes greater.

[0007]

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIGS. << First Embodiment >>

FIG. 1 is a vertical sectional view of a neck portion 8 and a cone portion 9 showing a first construction of a cathode ray tube embodying the present invention, and FIG. 2 is a sectional view taken along line II-II of FIG. In FIG.
Two compensation coils 5 are provided above and below the neck portion 8 and the cone portion 9 of the cathode ray tube 1 via an insulating film 10, respectively. A deflection yoke 6 having a horizontal deflection coil 15 and a vertical deflection coil 16 is provided outside the compensation coil 5. A device including the deflection yoke 6 and the ferrite core 17 is called a deflection device. The deflection device has a tubular shape.

The two compensation coils 5 are connected in series, and one terminal 20 is connected to the outer conductive film 4 provided on the outer surface of the glass bulb 31 of the cathode ray tube 1. The outer conductive film 4 is connected to the ground wire of the display device in which the cathode ray tube 1 is incorporated. Further, the other terminal 21 of the compensation coil 5 is open without being connected to anything. By connecting in this way, a voltage of opposite polarity synchronized with the deflection voltage waveform is induced in the compensation coil 5. An electric field having a polarity opposite to that of the leakage electric field emitted from the deflecting device including the deflection yoke 6 is generated by the voltage having the opposite polarity. As a result, the leakage electric field generated by the deflecting device is suppressed.

The two compensation coils 5 are sandwiched between the deflection yoke 6 and the cathode ray tube 1, and the glass bulb 3 of the neck portion 8 and the cone portion 9 of the cathode ray tube 1 in which the deflection yoke 6 is provided.
It is desirable that they are arranged so as to face each other with 1 in between.
In FIG. 1, the case where two compensation coils 5 are provided is shown.
Even when only one piece is provided, the leakage electric field can be suppressed.

FIG. 3 is a plan view showing the shape of the compensation coil 5. As shown in the figure, the compensating coil 5 is wound in a substantially triangular spiral shape and is formed in a flat plate shape at the time of manufacture. The compensation coil 5 is insulated by an insulating film having flexibility and elasticity. FIG. 4 shows a state in which the compensation coil 5 is arranged in the neck portion 8 and the cone portion 9 of the cathode ray tube 1. When attached to the cathode ray tube 1 as shown in the figure, the compensation coil 5 is bent along the curved surfaces of the neck portion 8 and the cone portion 9 so that the spiral surface substantially intersects the magnetic field of the horizontal deflection coil. Deploy.

By arranging the compensating coil 5 so as to face the neck portion 8 and the cone portion 9 of the cathode ray tube 1 as in this structure, the horizontal deflection coil can be arranged as compared with the case where it is arranged only in the neck portion 8. Can be used more effectively, and the reverse polarity voltage induced in the compensation coil 5 increases. As a result, the effect of suppressing the leakage electric field is enhanced.

In order to confirm the effect of the cathode ray tube having the compensation coil 5 constructed as described above, the strength of the VLF leakage electric field generated in front of the display device using this cathode ray tube was measured.

In measuring the VLF leakage electric field, a 17-inch cathode ray tube was used as a sample, and it was examined whether or not the above-mentioned Swedish safety standard TCO was satisfied. 30c from the front of the display device according to the measurement conditions of the TCO standard
The VLF leakage field strength at a distance of m was measured. The results are shown in Table 1.

[0016]

[Table 1]

As shown in Table 1, it is 0.8 V / m in the cathode ray tube of Example 1 and 2.4 V in the conventional example.
Was / m. As is clear from Table 1, the cathode ray tube of Example 1 has a VLF leakage electric field strength that is one-third of that of the conventional cathode ray tube, and the suppression effect thereof is large. The cathode ray tube of Example 1 sufficiently satisfies the value of 1.0 V / m of the Swedish safety standard TCO, which is not satisfied by the conventional cathode ray tube.

<Second Embodiment> In the first embodiment, the insulating film 10 is provided between the glass bulb 31 and the compensation coil 5, but the entire compensation coil 5 is covered with a flexible insulating film. However, the same effect can be obtained.

FIG. 5 is a sectional view of a deflection device in which the compensation coil 5 of the second embodiment is provided on the inner surface of the deflection yoke 6. In FIG. 5, the compensation coil 5 is entirely covered with an insulator 30 having flexibility and elasticity. The compensation coil 5 covered with the insulator 30 is provided on the inner surface of the deflection yoke 6. Other configurations are the same as those in the first embodiment. In this embodiment, since the compensation coil 5 and the insulator 30 are integrated and provided on the inner surface of the deflection yoke 6, the process of attaching the compensation coil 5 to the cathode ray tube 1 is simplified. As in the first embodiment, the compensation coil 5 is generated by the deflecting device by inducing a reverse polarity voltage synchronized with the deflection voltage waveform to generate a leakage electric field and a reverse electric field generated by the deflecting device. Suppress leakage electric field. In the first and second embodiments of the present invention, as shown in FIG. 4, the compensating coils 5 are arranged above and below the cathode ray tube 1 so that the spiral surface of the compensating coil is substantially the same as the magnetic field of the horizontal deflection coil. However, the compensation coil 5 is arranged on the left and right of the cathode ray tube 1 (not shown) so that the spiral surface of the compensation coil substantially intersects the magnetic field of the vertical deflection coil. It may be made by someone. In this case, the leakage electric field generated from the vertical deflection coil can be suppressed.

[0020]

According to the present invention, the cathode ray tube in which the deflection yoke is installed so that at least one compensation coil having one end grounded and the other end open is sandwiched between the deflection yoke and the cathode ray tube. It was provided on the neck and cone of the. With this configuration, it is possible to extremely effectively suppress the leakage electric field generated by the high-voltage flyback pulse applied to the horizontal deflection coil arranged around the neck portion of the cathode ray tube.

By providing two compensating coils so as to face each other with the glass bulb of the neck portion and the cone portion sandwiched therebetween, a stronger electric field of opposite polarity is generated, and the effect of suppressing the leakage electric field is further improved.

Further, the compensating coil before mounting is formed in a flat plate shape and insulated by a flexible insulating film, which facilitates the manufacture, and since it is flexible, it can be mounted along the curved surface of the glass bulb.

[Brief description of drawings]

FIG. 1 is a sectional view of a cone portion and a neck portion of a cathode ray tube according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a plan view of a compensation coil.

FIG. 4 is a perspective view showing a state in which the compensation coil of FIG. 3 is attached to a cone portion and a neck portion of a cathode ray tube.

FIG. 5 is a sectional view of a cone portion and a neck portion of a cathode ray tube according to a second embodiment of the present invention.

[Explanation of symbols]

1 cathode ray tube 5 compensation coil 6 Deflection yoke 7 Horizontal deflection coil 8 neck 9 Cone part 10 Insulating film

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-7-335144 (JP, A) JP-A-7-176434 (JP, A) JP-A-6-103934 (JP, A) Actual Kaihei 5- 90791 (JP, U) (58) Fields surveyed (Int.Cl. ⁷ , DB name) H04N 9/29 H01J 29/00

Claims (2)

(57) [Claims] 1. A glass bulb having a front panel, a cone portion and a neck portion sequentially formed, and a cylindrical shape having a horizontal deflection coil and a vertical deflection coil on the outer peripheral surfaces of the cone portion and the neck portion of the glass bulb. comprising a deflection device, and a compensation coil that is disposed between the cylindrical inner peripheral surface of the outer peripheral surface and the deflection device of said glass bulb, said compensation coil forms a winding in a spiral, the spiral
The outer peripheral surface of the box-shaped part is surrounded by an insulator.
Grounded and open at the other end, the spiral surface is horizontally deflected
The magnetic field of the coil or the magnetic field of the vertical deflection coil
It will be sandwiched between the deflection yoke and the cathode ray tube so that
And the compensation coil is synchronized with the deflection voltage waveform of the deflection device.
Generated by the deflection device
By generating an electric field of the opposite polarity to the leakage electric field
A cathode ray tube characterized by suppressing a leakage electric field generated from a deflecting device . 2. The compensating coil comprises a first compensating coil and a second compensating coil which are opposed to each other with a glass bulb in between, and the first compensating coil and the second compensating coil are connected in series. The compensation coils connected in series have one end grounded and the other end open.
1. The cathode ray tube according to 1 .