JP2000200562A - Electron gun of color cathode-ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electron gun of a cathode-ray tube capable of reducing the influence by an eddy current, capable of suppressing generation of the eddy current with a simple structure, and capable of suppressing cost increase, by suppressing generation of the eddy current caused by an external magnetic field in an electrode of the electron gun. SOLUTION: In this electron gun of a cathode-ray tube, an electrode l is composed of material having more than ten times as large a resistivity as stainless, for example, tungsten or the like, or the electrode 1 is composed of an insulator, followed by coating a conductor 3 on the surface thereof by painting, vapor deposition, sticking or the like, or the electrode 1 is composed by forming a great number of slits.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color cathode ray tube (CRT: Cathode-Ray-Tube) electron gun used for a monitor for a computer display or the like, and more particularly to an electron gun for suppressing generation of eddy current in the electrode. ,
The present invention relates to a cathode ray tube electron gun capable of reducing the influence of eddy current.

[0002]

2. Description of the Related Art As shown in FIG.
The electron beam emitted from the cathode of the electron gun 12 causes the fluorescent screen 13 to emit light. The electron beam emitted from the cathode is converged by the electron gun 12 and deflected by the deflection yoke (DY) 14 so as to be deflected. 13 to form an image. In such a color cathode ray tube 11, the material used for the electrode of the electron gun 12 is metal, and stainless steel (SUS) is mainly used.

However, the metal (stainless steel) used for the conventional electrode has a low resistivity, and an eddy current is generated when the alternating frequency is increased even by a weak external magnetic field, which adversely affects the correction magnetic field as described later. was there. Electron gun 1
The factors that cause the eddy current in the two electrodes include the horizontal deflection magnetic field generated on the neck 14a side of the deflection yoke 14 and the magnetic field generated by the correction current flowing through the dynamic correction coil 15. In particular, many recent computer display monitors use the dynamic correction coil 15 for convergence and focus adjustment due to higher definition, which has been a factor of eddy current generation.

[0004] The dynamic correction coil 15 is provided in FIG.
Since the magnetic field passes through the electrode of the electron gun 12 because the magnetic field passes through the electrode of the electron gun 12 as shown in FIG.
As shown in (B), an eddy current is generated in the electrode 16 of the electron gun 12, which affects the correction magnetic field. FIG. 6 shows actually measured values of the differential waveform of the generated magnetic field when a triangular current of 91 kHz and 31 kHz is applied to the dynamic correction coil 15, and the waveform differs between the case with the electron gun electrode and the case without the electron gun electrode. You can see that it is occurring.

[0005] Further, since the horizontal deflection frequency is increased and the number of scans is increased due to the multi-scanning, the magnitude and phase of the generated eddy current also changes because the frequency is not constant. For this reason, the following problems have occurred. (1) Since the amount of correction by the dynamic correction coil 15 is reduced due to the magnetic field due to the eddy current generated in the canceling direction with respect to the correction magnetic field, a high-power drive circuit is required correspondingly, resulting in an increase in cost. become. (2) Since the correction amount and phase change depending on the frequency,
Particularly in the case of multi-scanning, frequency drift occurs, and high-precision image quality cannot be obtained.

(3) In addition, convergence swells due to over-correction or under-correction of convergence correction due to a phase change.
This is because, as shown in FIG. 6, the differential waveform of the magnetic field generated by the current applied to the correction coil is 91 kHz and 31 kHz.
z is almost a rectangular wave, and the differential waveform of the generated magnetic field of this rectangular wave becomes dull due to the influence of the eddy current flowing through the electron gun, thereby causing a phase shift. Even if it enters, an eddy current remains on the electrode of the electron gun, and this causes a so-called convergence swell in which the convergence correction is overcorrected or undercorrected.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to address the above problems, and a first object of the present invention is to suppress generation of an eddy current due to an external magnetic field in an electrode of an electron gun. Accordingly, it is possible to provide an electron gun of a color cathode ray tube which can reduce the influence of the eddy current on the high precision image quality required with the recent increase of the horizontal deflection frequency or the multi-scan and can solve the above-mentioned problem. It is in. Another problem of the present invention is that
An object of the present invention is to provide a color cathode ray tube electron gun capable of suppressing the generation of an eddy current due to an external magnetic field in the electrode of the electron gun with a simple structure and suppressing an increase in cost.

[0008]

In order to solve the above-mentioned problems, an electron gun of a color cathode ray tube according to the present invention is configured such that electrodes are made of a material having a resistivity of at least 10 times that of stainless steel. The eddy current has a degree of influence on convergence of about 10 to 20% in the conventional electron gun, and it is necessary to reduce the degree of influence to at least 1/10 or less. By configuring the electrode with a material having a resistivity of at least 10 times or more of the stainless steel electrode mainly used in the electrode, generation of eddy current in the electrode is suppressed,
The degree of influence by this can be reduced to at least 1/10 or less.

The electron gun for a color cathode ray tube according to the present invention is characterized in that, in the above electron gun for a color cathode ray tube, the material is made of tungsten, and the electrode is made of tungsten. By
Since the resistivity can be at least ten times or more that of the conventional stainless steel electrode, generation of eddy current in the electrode due to an external magnetic field can be suppressed.

Further, the electron gun of the color cathode ray tube according to the present invention is characterized in that the electrodes are made of an insulator and the surface thereof is covered with a conductor, whereby the electrode structure is made of an insulator. In addition, since the generation of the eddy current can be suppressed by reducing the thickness of the conductor portion of the electrode, the influence of the eddy current generation can be reduced.

The electron gun for a color cathode ray tube according to the present invention is the electron gun for a color cathode ray tube described above, wherein the conductor is coated on the surface of the insulator by coating, vapor deposition, sticking, or the like. The feature is that by coating the conductor on the surface of the insulator by coating, vapor deposition, sticking, or the like, an electrode in which the conductor portion is thinned and generation of eddy current is suppressed can be easily configured.

Further, the electron gun of the color cathode ray tube according to the present invention is characterized in that a large number of slits are provided in the electrodes. By forming a large number of slits in the electrode, generation of eddy current can be suppressed relatively easily.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.
This will be described with reference to FIG. FIG. 1 is a perspective view showing a configuration of an electrode in an electron gun of a color cathode ray tube according to an embodiment of the present invention, and FIG. 2 is a perspective view showing a configuration of an electrode in an electron gun of a color cathode ray tube according to another embodiment of the present invention. Figure,
FIGS. 3A and 3B are perspective views each showing a configuration of an electrode in an electron gun of a color cathode ray tube according to another embodiment of the present invention.

As described in the section of the prior art, when an eddy current is generated by an external magnetic field inside the electrode of the electron gun of the color cathode ray tube, the eddy current affects the correction magnetic field and causes the various problems described above. . In the electrode of the conventional electron gun, in the case of a stainless steel (SUS) electrode, which is mainly used, the degree of influence of the generated eddy current on the convergence is about 10 to 20%. In order to solve the above-mentioned problem caused by the generation of the eddy current, the degree of the influence of the eddy current on the convergence needs to be at least 1-2% or less.

This means that the degree of influence of eddy current on convergence is at least one-tenth that of the conventional one.
It means that you have to: The conventional stainless steel electrode has a very low resistivity, and an eddy current is generated when the alternating frequency becomes high even with a weak external magnetic field. Therefore, in order to reduce the degree of influence of eddy current on convergence at least one-tenth or less of the conventional one,
The resistivity of the electrode of the electron gun needs to be at least 10 times or more that of a conventional stainless steel electrode.

In order to make the resistivity of the electrode of the electron gun at least ten times that of the conventional stainless steel electrode, as in the embodiment shown in FIG. By forming an electrode structure on the surface of the electrode 1 and covering the surface of the electrode structure with the conductor 3, the electrode 1 having a resistivity to eddy current at least 10 times that of the stainless steel electrode can be formed. Note that the conductor 3 can be coated by painting, vapor deposition, pasting, or the like on the surface of the insulator 2.

In addition, even if the material is metal, stainless steel (SU)
By configuring the electrode using tungsten having a higher resistivity than that of S), the resistivity of the electrode can be at least ten times that of the conventional stainless steel electrode. Further, as shown in FIG. 2, it is also possible to cover the base of the electrode structure made of the insulator 2 so as to form the electrode pattern 4 of the conductor 3.

Furthermore, as shown in FIGS. 3A and 3B, when an electrode 5 having a low resistivity is used as a configuration other than the above, a number of slits 6 are formed in the electrode 5 vertically. By inserting in the direction or the lateral direction, generation of eddy current can be suppressed. This is because the eddy current generated in each part can be made smaller by providing the slit 6, whereby the eddy current generated in the entire electrode can be made smaller.

According to the above-described embodiment, the electrode of the electron gun is made of a material such as tungsten or the like having at least 10 times the resistivity of the stainless steel electrode, or the electrode structure formed by the insulator 2 is used. Of the electrode 1 having a high resistivity to eddy current by covering the surface of the conductor 3 with the conductor 3, or by forming a large number of slits 6 in the electrode 5, the resistivity of the eddy current to the eddy current is higher than that of the stainless steel electrode. Since a large electrode can be configured, eddy current generation in the electrode can be suppressed, and the degree of influence of the eddy current on the correction magnetic field can be reduced to at least 1/10 or less of the conventional stainless steel electrode.

Accordingly, the influence of the eddy current can be reduced, and the horizontal deflection frequency can be effectively increased and the misconvergence can be effectively adjusted by multi-scanning.
In addition, it is possible to prevent a reduction in the correction amount due to the dynamic correction coil, to save the cost by eliminating the need for a high-power drive circuit, and to prevent a frequency drift due to a change in the correction amount and phase depending on the frequency. Significant effects can be expected, for example, accurate image quality can be obtained, and convergence undulation due to phase change can be prevented.

[0021]

As described above in detail, according to the electron gun of the color cathode ray tube according to the present invention, generation of an eddy current due to an external magnetic field in the electrode of the electron gun can be suppressed. The effect of eddy currents on the high-definition image quality required with the increase in horizontal deflection frequency or multi-scan is reduced, the amount of correction by the coil is reduced,
Problems such as occurrence of frequency drift and convergence undulation due to phase change can be solved.

The generation of an eddy current due to an external magnetic field in the electrode of the electron gun can be relatively easily determined by selecting a material forming the electrode, a structure in which a conductor is coated on the surface of an insulator, or a structure in which a slit is formed. Since it can be suppressed by a simple structure, cost increase can be suppressed.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of an electrode in an electron gun of a color cathode ray tube according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a configuration of an electrode in an electron gun of a color cathode ray tube according to another embodiment of the present invention.

FIG. 3 is a perspective view showing electrode configurations (A) and (B) in an electron gun of a color cathode ray tube according to another embodiment of the present invention.

FIG. 4 is a sectional view showing a schematic configuration of a conventional color cathode ray tube.

5A and 5B are a vertical sectional view and a top view, respectively, showing a configuration of an electrode portion in an electron gun of a conventional color cathode ray tube.

FIG. 6 is a waveform diagram showing measured values of a differential waveform of a magnetic field generated in an electron gun of a conventional color cathode ray tube.

[Explanation of symbols]

1 ... electrode, 2 ... insulator, 3 ... conductor, 4 ... electrode pattern,
5 ... electrode, 6 ... slit

Claims (5)

[Claims] 1. An electron gun for a color cathode ray tube, wherein an electrode of the electron gun has a resistivity of at least one of stainless steel.
An electron gun for a color cathode ray tube, wherein the electron gun is made of a material having 0 times or more. 2. An electron gun for a color cathode ray tube according to claim 1, wherein said material comprises tungsten. 3. An electron gun for a color cathode ray tube, wherein an electrode of the electron gun is formed of an insulator, and a surface thereof is covered with a conductor. 4. The electron gun for a color cathode ray tube according to claim 3, wherein the conductor is coated on the surface of the insulator by painting, vapor deposition, sticking, or the like. 5. An electron gun for a color cathode ray tube, wherein the electrode of the electron gun is provided with a number of slits.