JPH11260285A - Control method for color crt and electron beam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a precise beam spot diameter on an entire screen range, without degrading a convergence characteristic by setting a focusing voltage of an electron gun to a specific ratio of an accelerating voltage. SOLUTION: A focusing voltage of an electron gun is set to a value which is 31% highery than an acceleration voltage. Preferably, a deflection yoke equipped with a static quadruple magnetic field generating device having a focusing operation is provided in the horizontal direction, and a long axis part of a facing part of a pair of electrodes constituting the main lens of the electron gun is far away from a screen comparing with a short axis part. An interval between the pair of electrodes at the facing parts of the pair electrodes is preferably constant in the range of 0.7-1.5 mm. In addition, it is preferable that control method that increases dynamic voltage is reduced by applying a quadruple magnetic field to an electron beam, and a control method that the long axis part of the facing parts of the pair of electrodes is a color CRT which is at a position far away from the screen comparing with the short axis part, and an asymmetric electric field generated between the pair of electrodes improves the inside deflection of the electron beam are preferable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a color CRT and a method for controlling an electron beam of the color CRT.

[0002]

2. Description of the Related Art FIG.
Is a cross-sectional explanatory view showing a configuration of a conventional color CRT disclosed in, for example, Japanese Patent Application Laid-Open No. 4-277449, and FIG. 9 is an enlarged cross-sectional explanatory view of an electron gun portion.

In FIG. 8, reference numeral 11 denotes an electron gun portion (details are shown in FIG. 9), and reference numeral 12 denotes an external quadrupole magnet.
3 is a deflection yoke, 14 is a neck glass. In FIG. 9, reference numeral 31 denotes a G1 electrode, and 32 denotes a G2 electrode.
Reference numeral 33 denotes a G3 electrode, reference numeral 34 denotes a G4 electrode, reference numeral 35a denotes a G51 electrode, reference numeral 35b denotes a G52 electrode, reference numeral 36 denotes a G6 electrode, and reference numeral 37 denotes a cathode.

Further, reference numeral 101 denotes an EC2 terminal,
2 is an Efs terminal, 103 is an Eb terminal, 10
Reference numeral 4 denotes an Efd power supply. Also, R ₁ , R ₂ , R ₃ and R ₄
Schematically shows an electric field lens.

The cathode 37, the G1 electrode 31, and the G2 electrode 32 are collectively referred to as a triode 30.

The color CRT has at least an electron beam generating section, a main lens section, and an electron beam deflecting section. The electron beam generating section includes a triode section 30, and the main lens section includes G52 electrodes 35b and G6. The electron beam deflecting unit includes the electrode 36 and the deflection yoke 13.

A method for controlling an electron beam in an electron gun of a color CRT having such a configuration will be described. Normally, a fixed voltage Eb for acceleration (for example, 25 kV or 27 kV) is applied to the G6 electrode 36 for each of the electrodes shown in FIG. 9, and a focusing voltage is applied to the G51 electrode 35a and the G52 electrode 35b. The fixed voltage Efh (for example, 25
%, Ie 6.75 kV). The G4 electrode 34 has a fixed voltage EC2 (for example, 700).
V) and E3 are applied to G3 to form a uni-potential pre-lens. Due to the focusing action of the pre-lens, the electron beam is narrowed down to a certain extent and is incident on the main lens portion.

According to the configuration of such a conventional electron gun,
Since the electron beam incident on the pre-lens has a spread, there is a problem that the beam spot is blurred due to the influence of the spherical aberration of the pre-lens and the main lens portion.

The present invention provides a color CRT having an electron gun for making the beam spot diameter fine over the entire screen without deteriorating the convergence characteristics while maintaining the dynamic voltage at the same level as the conventional one, and a method for controlling the electron beam. The purpose is to do.

[0010]

In order to solve the above-mentioned problems, a color CRT according to a first aspect of the present invention is a color CRT having at least an electron gun including an electron beam generating unit and a main lens unit. The focus voltage of the electron gun is 31% or more of the acceleration voltage.

According to a second aspect of the present invention, there is provided a color CRT having at least an electron gun including an electron beam generator and a main lens, wherein a focus voltage of the electron gun is at least 31% of an acceleration voltage. In addition, a deflection yoke provided with a static quadrupole magnetic field generator having a horizontal convergence function is provided.

A color CRT according to a third aspect of the present invention is a color CRT having at least an electron gun including an electron beam generator and a main lens, wherein the focus voltage of the electron gun is 31% or more of the acceleration voltage. Further, a deflection yoke provided with a static quadrupole magnetic field generator having a horizontal converging action is provided, and a long axis portion of a facing portion of a pair of electrodes constituting a main lens of the electron gun has a short axis. It is located farther from the screen than the shaft.

According to a fourth aspect of the present invention, there is provided a color CRT wherein a distance between the pair of electrodes at a portion opposed to the pair of electrodes is constant.

According to a fifth aspect of the present invention, there is provided a color CRT wherein the interval between the pair of electrodes is constant at 0.7 to 1.5 mm.

According to a sixth aspect of the present invention, there is provided a method for controlling an electron beam, comprising an electron gun comprising at least an electron beam generating section and a main lens section, wherein a focus voltage of the electron gun is 31% or more of an acceleration voltage, and A method for controlling an electron beam of a color CRT provided with a deflection yoke provided with a static quadrupole magnetic field generator having a horizontal converging action, wherein a dynamic voltage is increased by applying a quadrupole magnetic field to the electron beam. Is to be reduced.

According to a seventh aspect of the present invention, there is provided a method for controlling an electron beam, comprising at least an electron beam generating portion and a main lens portion, wherein a focus voltage of the electron gun is 31% or more of an acceleration voltage and converges in a horizontal direction. A deflection yoke provided with a static quadrupole magnetic field generator having an effect, and
A method for controlling an electron beam of a color CRT in which a long axis portion of a portion facing a pair of electrodes constituting a main lens of the electron gun is located farther from a screen than a short axis portion. The asymmetric electric field generated between the electrodes of
This is to improve the inside deflection of the electron beam.

[0017]

Embodiments of the present invention will be described below in more detail with reference to the accompanying drawings.

Embodiment 1 A color CRT according to Embodiment 1 of the present invention has the same structure as the above-described conventional color CRT.
In the present embodiment, the focus voltage of the electron gun is set to 31% or more of the acceleration voltage.

The setting of the focus voltage (Efs) will be described. According to the combination of the voltages applied to the respective electrodes shown in FIG. 9, an electron beam (hereinafter simply referred to as a beam)
Before entering the main lens R ₄ , two converging lenses R ₁ ,
It is converged in advance by R ₂ . If the diameter of the beam incident on the main lens R ₄ is large, the beam spot projected on the screen becomes blurred due to the influence of spherical aberration.
As for R ₁ and R _2, a stronger lens is better. However, in order to increase the strength of R ₂ , the electrode opening diameter is reduced, or G
Taking a means such as increasing the thickness of the fourth electrode plate thickness, the spherical aberration of the R ₂ itself, a beam spot projected on the screen tends to deteriorate rather. Therefore, in this embodiment triode strongly the lens strength of the R ₁ (cathode, G
1, the voltage applied to G3, ie, E, in order to reduce the divergence angle of the beam emitted from the G2 electrode.
fs was increased. Specifically, the anode voltage Eb of 31
% Or more. In order to make Efs 31% or more of Eb, for example, it is possible to move the triode in a direction away from the screen or to increase the main lens strength. It should be noted that the beam emitted from the triode portion is several tens to several hundreds μ.
Although it is a bundle of electrons of A, not all electrons go straight in parallel to the Z axis, but also include a component that emits at an opening angle with respect to the Z axis. ,
In the distribution of the current density with respect to this angle, the angle at which the current density becomes 95% is referred to as “divergence angle”.

Here, the reason for limiting to 31% or more is that the beam diameter can be made fine.

FIG. 1 is a graph showing how the divergence angle of the beam emitted from the triode is reduced by increasing Efs as described above. In FIG. 1, a solid line indicates a divergence angle, and a broken line indicates a spherical aberration diameter. From FIG. 1, it can be seen that increasing Efs from a typical value of 6.75 kV to 8.75 kV reduces the divergence angle by about 19%.

The width of the blur due to spherical aberration in the beam spot on the screen is proportional to the spherical aberration coefficient of the main lens and the cube of the divergence angle of the beam incident on the lens. %, The bokeh width is 53
%. That is, when the divergence angle is reduced by 19%, the divergence angle is represented by the reference value a, which is 0.81a, and the spherical aberration is proportional to the cube of the divergence angle.
1a) ³ = 0.53a ³ , and the blur width due to spherical aberration is reduced to 53%.

Embodiment 2 In this embodiment, an external quadrupole magnetic field generator is provided at the entrance side of the deflection yoke, and a quadrupole magnetic field is applied to the beam to statically converge horizontally (ie, diverge in the vertical direction). Generating a lens reduces the dynamic voltage.

FIG. 4 is an explanatory plan view of the external quadrupole magnetic field generator. In the figure, reference numeral 91 denotes an external quadrupole magnetic field generator, which is a donut-shaped permanent magnet as shown in FIG. 4, and has a pole arrangement as shown when viewed from the screen side. This magnetic field causes the electron beam to undergo a horizontal focusing operation.

FIG. 2 is an explanatory diagram showing the relationship between Efs and the dynamic voltage.

As shown in FIG. 2, when Efs is set high, the dynamic voltage increases. Since the dynamic voltage is synchronized with the horizontal deflection frequency, a higher voltage results in a costly burden on the high frequency circuit.

FIG. 3 is an explanatory sectional view showing a dynamic focus structure. Here, a dynamic focus (hereinafter abbreviated as DBF) structure will be described with reference to FIG.
In FIG. 3, 60 is a beam, 61 is a main lens, 62 is a screen, 63 is a deflection yoke, 6
Reference numeral 4 denotes a DBF lens. P is the object point, V and H
Indicates the V direction and the H direction, respectively. 3A shows a case where the beam is directed to the center of the screen, and FIGS. 3B and 3C show a case where a quadrupole magnetic lens by self-convergence DY is inserted when the beam is deflected to the periphery of the screen. .

When the beam is deflected to the periphery of the screen, FIG.
As shown in (b), a situation occurs in which the light converges in the horizontal direction but overconverges in the vertical direction due to the asymmetric magnetic field of the self-convergence DY. In order to correct this, as shown in FIG. 3C, a DBF quadrupole lens is provided between the G51 electrode and the G52 electrode, and the voltage Efd synchronized with the horizontal deflection cycle is superimposed on the G52 electrode. This is the so-called DBF
Structure.

When deflecting the periphery of the screen, the DBF lens is a vertical diverging lens. In this case, since the convergence function is horizontal, the convergence of the main lens is weakened to cancel the convergence. E
The electrodes of the DBF lens must be designed so that the horizontal convergence does not change regardless of the value of fd.

The reason why Efd increases as Efs increases will be described below. High Efs corresponds to the weakness of the main lens, and the horizontal convergence effect of the DBF lens when Efd is applied cannot be offset by weakening of the main lens. Therefore, only a small DBF electrode can be attached, and a high Efd is required.

Next, the reason why the dynamic voltage is reduced will be described with reference to FIG. FIG. 5 is an explanatory diagram showing the relationship between the strength of the external quadrupole magnetic field and the dynamic voltage. 7
1 is a voltage required for the quadrupole lens, and 72 is a main lens voltage reduction amount. In FIG. 5, the strength of the quadrupole lens at the time of peripheral deflection is defined as Efd at the time of peripheral deflection with reference to Efd at the center.
The value of d, that is, the voltage required for the quadrupole lens. Further, the voltage decrease of the main lens at the time of peripheral deflection is a decrease in the main lens voltage at the time of peripheral deflection with reference to the voltage applied to the main lens at the center. This corresponds to the weakening of the main lens for canceling the horizontal convergence of the DBF during peripheral deflection.

According to FIG. 5, the voltage 71 required for the quadrupole lens does not change much even when the external quadrupole magnetic field is increased.
The main lens voltage reduction amount 72 decreases linearly. Therefore, it is not necessary to weaken the main lens so much when the DBF is operated, so that the DBF electrode can be made large. This can increase the sensitivity of the DBF,
A low dynamic voltage can be realized.

Third Embodiment In the second embodiment, when an external quadrupole magnetic field of horizontal convergence is applied, the convergence characteristic is deteriorated, and the color CR is reduced.
In the color display of T, red is in the -X direction and blue is +
An under state that goes too far in the X direction results. In the present embodiment, in order to solve this, a configuration and a method for improving the inward deflection of the electron beam by inclining the facing part of a pair of electrodes constituting the main lens will be described. FIG. 6 is a perspective explanatory view showing the main lens opposing portion according to the present embodiment. In FIG. 6, reference numeral 21 denotes a main lens facing view, 22 denotes a G6 electrode, 23 denotes a G52 electrode,
24 indicates a cathode side direction, 25 indicates a screen side direction, of the screen-side end faces of the G52 electrode 23, an end face part indicated by L1 is called a short axis part, and an end face part indicated by L2 is a long axis part. Called the part. L1 indicates a portion whose short axis portion is closer to the screen side, and L2 indicates a portion whose long axis portion is farther from the screen side.

FIG. 7 is an explanatory diagram showing an equipotential curve when the main lens facing portion is not inclined and when the main lens facing portion is not inclined. FIG. 7 shows only the lower part obtained by dividing the main lens part into upper and lower parts. If no inclination is provided, the horizontal component of the electric field on the trajectory of both side beams is directed toward the convergence direction on the G52 side and toward the weak divergence direction on the G6 side from the facing portion. On the other hand, when the beam is inclined, the beam receives a force in the direction of divergence because the component in the convergence direction of the electric field on the G52 side is weak. Therefore, by controlling this inclination, the convergence on the screen can be adjusted.

It is preferable to make the distance between the pair of electrodes constant at the opposing portion of the pair of electrodes in order to make the R, G, and B focus voltages uniform. Further, it is preferable to keep the interval between the electrodes constant within a range of 0.7 mm to 1.5 mm. The reason for limiting the distance between the electrodes to the above range is as follows:
In order to prevent a vacuum discharge due to a large potential difference applied between G2 and G6, the beam passing through the main lens portion receives a force due to the charging of the neck glass, and the beam position on the screen changes. It is to prevent.

With the above-described configuration, a good focus performance can be obtained, and a CRT having a sufficiently low dynamic voltage and good convergence characteristics can be obtained.

[0037]

The color CR according to claim 1 of the present invention.
T is a color CRT having an electron gun including at least an electron beam generating unit and a main lens unit. Since the focus voltage of the electron gun is 31% or more of the acceleration voltage,
The divergence angle can be reduced and an effect of obtaining a color CRT with a fine beam spot diameter can be obtained.

According to a second aspect of the present invention, there is provided a color CRT having at least an electron gun including an electron beam generator and a main lens, wherein a focus voltage of the electron gun is 31% or more of an acceleration voltage. In addition, since a deflection yoke provided with a static quadrupole magnetic field generator having a converging function in the horizontal direction is provided, a dynamic voltage can be reduced and a color beam spot with a fine beam spot diameter can be obtained.
It has the effect of obtaining T.

A color CRT according to a third aspect of the present invention is a color CRT having an electron gun including at least an electron beam generating unit and a main lens unit, wherein a focus voltage of the electron gun is 31% or more of an acceleration voltage. Further, a deflection yoke provided with a static quadrupole magnetic field generator having a horizontal converging action is provided, and a long axis portion of a facing portion of a pair of electrodes constituting a main lens of the electron gun has a short axis. Since it is located farther from the screen than the shaft portion, it is possible to deflect the side beam outward and to obtain a color CRT capable of maintaining convergence characteristics.

The color CRT according to the fourth aspect of the present invention has an effect that the focus voltages of R, G, and B are equalized because the interval between the pair of electrodes in the opposing portion of the pair of electrodes is constant.

According to a fifth aspect of the present invention, when the interval between the pair of electrodes is constant at 0.7 mm to 1.5 mm, a vacuum discharge at the main lens portion is prevented and a beam generated by charging the neck glass is provided. This has the effect of preventing a change in position.

According to a sixth aspect of the present invention, there is provided a method for controlling an electron beam, comprising an electron gun comprising at least an electron beam generating section and a main lens section, wherein the focus voltage of the electron gun is at least 31% of the acceleration voltage, and A method for controlling an electron beam of a color CRT provided with a deflection yoke provided with a static quadrupole magnetic field generator having a horizontal converging action, wherein a dynamic voltage is increased by applying a quadrupole magnetic field to the electron beam. Therefore, there is an effect that the cost of the dynamic voltage supply circuit can be reduced.

According to a seventh aspect of the present invention, there is provided a method for controlling an electron beam, comprising at least an electron beam generating portion and a main lens portion, wherein a focus voltage of the electron gun is 31% or more of an acceleration voltage and converges in a horizontal direction. A deflection yoke provided with a static quadrupole magnetic field generator having an effect, and
A method for controlling an electron beam of a color CRT in which a long axis portion of a portion facing a pair of electrodes constituting a main lens of the electron gun is located farther from a screen than a short axis portion. The asymmetric electric field generated between the electrodes of
Since the inside deflection of the electron beam is improved, there is an effect that good convergence characteristics can be maintained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a relationship between Efs and a divergence angle according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a relationship between Efs and a dynamic voltage according to the embodiment of the present invention.

FIG. 3 is an explanatory sectional view showing a dynamic focus structure according to the embodiment of the present invention.

FIG. 4 is an explanatory plan view showing an external quadrupole magnetic field generator according to the second embodiment.

FIG. 5 is an explanatory diagram showing a relationship between the intensity of an external quadrupole magnetic field and a dynamic voltage according to the second embodiment.

FIG. 6 is an explanatory perspective view showing a facing portion of a main lens according to a third embodiment.

FIG. 7 is an explanatory diagram for comparing the presence or absence of a facing portion of a main lens according to the third embodiment.

FIG. 8 is an explanatory sectional view of a conventional color CRT.

FIG. 9 is an enlarged sectional explanatory view of a conventional color CRT electron gun.

[Explanation of symbols]

11 electron gun part, 12 external quadrupole magnet, 13 deflection yoke, 14 neck glass, 21 main lens facing part, 2
2 G6 electrode, 23 G52 electrode, 30 triode, 61
Main lens, 63 deflection yoke, 64 DBF lens.

Claims (7)

[Claims] 1. A color CRT having an electron gun comprising at least an electron beam generator and a main lens, wherein a focus voltage of the electron gun is 31% or more of an acceleration voltage. 2. A color CRT having an electron gun comprising at least an electron beam generating section and a main lens section, wherein the focus voltage of the electron gun is 31% or more of the acceleration voltage, and the electron gun has a horizontal focusing function. C provided with a deflection yoke provided with a static quadrupole magnetic field generator having
RT. 3. A color CRT having an electron gun comprising at least an electron beam generating section and a main lens section, wherein a focus voltage of the electron gun is 31% or more of an acceleration voltage, and a horizontal focusing action. A deflection yoke provided with a static quadrupole magnetic field generating device having: a long axis portion of a portion facing a pair of electrodes constituting a main lens of the electron gun is longer than a short axis portion of the screen. Color CRT located far away. 4. The color CR according to claim 3, wherein a distance between the pair of electrodes at a portion opposed to the pair of electrodes is constant.
T. 5. The method according to claim 1, wherein an interval between the pair of electrodes is 0.7 to 1.5.
The color CRT according to claim 4, which is constant in mm. 6. An electrostatic gun having at least an electron gun comprising an electron beam generating section and a main lens section, wherein the focus voltage of the electron gun is 31% or more of an acceleration voltage and has a horizontal focusing function. A method for controlling an electron beam of a color CRT provided with a deflection yoke provided with a quadrupole magnetic field generator, wherein the method controls the electron beam by applying a quadrupole magnetic field to reduce an increase in dynamic voltage. 7. A static quadrupole magnetic field generator comprising at least an electron beam generator and a main lens unit, wherein a focus voltage of the electron gun is 31% or more of an acceleration voltage and has a horizontal converging function. And a long-axis portion of a pair of electrodes constituting a main lens of the electron gun is located at a position farther from the screen than a short-axis portion of the electron gun of the color CRT. A method for controlling a beam, comprising: improving an inward deflection of an electron beam by an asymmetric electric field generated between the pair of electrodes.