JPH026187B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to improving the static convergence of an electron gun for a cathode ray tube, particularly a color picture tube.

The electron gun according to the present invention can be applied not only to in-line type electron guns currently in use but also to delta type electron guns.

Note that static convergence refers to the effect of concentrating three electron beams on a single point at the center of the screen surface when there is no deflection in a general color picture tube.

FIGS. 1 and 2 are principle diagrams of a conventional in-line type electron gun. As a structure for concentrating a plurality of electron beams at one point, FIG. 1 shows a structure called an eccentric type, and FIG. 2 shows a structure in which the electrodes have a taper angle.

In FIG. 1, G5 is a focus electrode and G6 is a high-voltage electrode, which represents the main final stage lens portion of a BPF (bi-potential focus) type electron gun.

Note that the voltage applied to the high voltage electrode G6 is considerably higher than the voltage applied to the focus electrode G5. G is a green electron beam running in the center, R and B are red and blue electron beams running on both sides of the electron beam G, and S is a screen.

Each of the electron beams R, G, and B travels through the center of the hole in the focus electrode G5. Here, since the center axis of the focus electrode G5 along which the electron beam G is traveling is coincident with the center axis of the high voltage electrode G6, the electron beam G is connected to the focus electrode G5 and the high voltage electrode without changing the direction of travel. It is accelerated by the applied voltage, travels in a straight line, and hits a point S on the screen 5.
collides with 1.

However, the center axis of the focus electrode G5 on which the electron beams R and B are traveling is the center axis r of the high voltage electrode G6.
The electron beams R and B, which are located on the electron beam G side from 1 and b1 and have traveled along the center axis of the focus electrode G5, jump into the position are shifted from the center axes r1 and b1 of the high voltage electrode G6, so the electron beam R,
The traveling direction of the electron beam B is deflected toward the electron beam G side, and the electron beam B collides with the screen S due to the voltage applied to the focus electrode G5 and the high voltage electrode G6.
At this time, the center axis of the focus electrode G5 and the high voltage electrode G
The amount of deviation between the center axes r1 and b1 of 6, that is, the amount of eccentricity x
By adjusting the electron beams R, G, and B, the electron beams R, G, and B are focused on a point S1 on the screen S.

In FIG. 2, the same reference numerals as in FIG. 1 indicate the same or corresponding parts. In the structure shown in FIG. 2, the central axis of the focus electrode G5 and the central axis of the high-voltage electrode G6 coincide with each of the three R, G, and B electrodes.

However, the exit surface of the focus electrode G5 through which the electron beams R and B pass and the entrance surface of the high voltage electrode G6 are inclined at a taper angle θ from a surface perpendicular to the electron beam G toward the screen S side. Therefore, the electron beams R and B receive a force from the side opposite to the electron beam G near the exit of the focus electrode G5, and further receive a force from the high voltage electrode G6.
It also receives a force from the electron beam G side near the entrance.
However, since the voltage applied to the high-voltage electrode G6 is higher than the voltage applied to the focus electrode G5, the electron beams R and B receive a larger force on the electron beam G side.
The traveling direction is deflected toward the electron beam G side, and the electron beam is accelerated.
Collisions with screen S. In this case, the three electron beams R, G, and B are concentrated on one point S1 on the screen S by adjusting the taper angle θ.

In these conventional devices, focus adjustment and static convergence are performed simultaneously in the final stage electron lens section formed between the focus electrode G5 and the high voltage electrode G6.

However, if the diameter of the above-mentioned electron lens is constant, the focus voltage is determined by the length of the focus electrode G5 in the beam direction, and the static convergence is determined by the eccentricity x or the taper angle θ in the above-mentioned conventional structure.
Therefore, the focus voltage and static convergence have an independent relationship with each other.

Therefore, there is a drawback that the optimum focusing voltage and the optimum static convergence voltage do not necessarily match.

In addition, as a conventional method other than the above in which three electron beams R, G, and B are focused by a single electron lens, after the three electron beams R, G, and B pass through a single electron lens, There is a method of concentrating the three electron beams R, G, and B on one point S1 on the screen S by applying an electrostatic force to the electron beams R and B running on both sides of the electron beam G running on the screen. However, in order to carry out this method, it is necessary to use another high voltage as high as the voltage applied to the high voltage electrode G6 in order to create this electrostatic force.

However, it is difficult to supply this separate second high voltage, and it also has the disadvantage of causing deterioration in breakdown voltage.

This invention has been made to eliminate the drawbacks of the conventional ones as described above, and is effective in making the focus optimum voltage and the static convergence optimum voltage match, and also prevents breakdown voltage deterioration. The purpose is to provide an effective electron gun.

FIG. 3 is a diagram of the basic principle of the electron gun of the present invention. In the figure, K _B , K _G , and K _R are cathodes for emitting electron beams, and cathode K _G is located between cathodes K _B and K _R. The cathodes K _B and K _R are each tilted toward the cathode K _G so that the emitted electron beams intersect with each other.

R, G, and B are electron beams emitted from each cathode K _B , K _G , and K _R , S is a screen, and L is a single electron lens common to the three electron beams R, G, and B. This principle In the figure, it is assumed that there is no aberration. Three electron beams B, G, and R are passed through an electron lens L.
If the electron beams S, G, and R are focused on the same point S1 on the screen S after passing through the electron lens L, each electron beam S, G, and R will be focused at the focusing point C _B , C _G , C _R , respectively, before passing through the electron lens L.
It is safe to assume that these points C _B , C _G , and _CR coincide at a common point C _O .
Points C _B , C _G , and _CR are virtual and not shown.
This is because the lens L is assumed to have no aberrations since the point C _O is a coincident point, and this point C _O is defined as a cross point. In this case, the three electron beams B, G, and R are equivalent to a single beam emitted from a single cross point _CO . Also, each electron beam B at the cross point C _O ,
Images of G and R are projected at one point S1 on the screen S. Therefore, this cross point C _O becomes the optimal focus point. In other words, the focus voltage and the static convergence are in a dependent relationship with each other, and the optimum focus voltage and the optimum static convergence voltage can be matched.

This invention will be described in more detail.

In principle, the electron lens could be assumed to have no aberration as described above, but in reality, the electron lens L has spherical aberration, and therefore the three electron beams R,
When G and B are focused on a point C _O and then passed through an electron lens L, an electron beam G and an electron beam G running in the center are formed.
A difference in focal length occurs between the electron beams R and B running on both sides of the screen S, and the electron beams are not focused on a single point on the screen S. Furthermore, there is a difference in focus voltage between the electron beam G and the electron beams R and B. Therefore, in reality, the focusing points of the three electron lenses R, G, and B in front of the electron lens L are C _R ,
C _G and C _B are not focused on one point C _O , but after passing through the electron lens L, the convergence point C _R and C B of the electron beams R and _B , which have the same focal length, is focused at a point C ₁ which is closer to the lens L than the point C _O. (not shown) to match each other. At this time, when the three electron beams R, G, and B are focused on a point _S1 on the screen, the electron beam R in front of the electron lens L is
The cross point C ₁ between and B is formed on the axis of the lens L, slightly shifted toward the electron lens L side from the focal point C _G of the electron beam G.

This invention is based on this idea, and for example, in the case where three electron beams are used, the focusing point or virtual focusing point of the two electron beams in front of the electron lens (hereinafter, both will be collectively referred to as the focusing point when describing the invention. ) is the same point, that is, the cross point C ₁ is set,
This is to match the focus optimum voltage and the static convergence optimum voltage.

An embodiment of the present invention will be described below with reference to FIG.

FIG. 4 shows a conventional bipotential type electron gun to which the above-described present invention is applied. In the figure
K _R , K _G , K _B , R, G, B, and S are the same or corresponding parts to the same reference numerals in FIG. G ₁ is the control electrode,
G ₂ is an accelerating electrode, G ₅ is a focus electrode, and G ₆ is a high voltage electrode. Electrodes G ₅ and G ₆ generate three electron beams R, G,
A single electron lens L common to B is formed.

Ef (5~8KV) to electrode G ₅ , Eb (20~30KV)
is the supply voltage applied to electrode G ₆ .

C _G is the electron beam G before entering the electron lens L.
is the convergence point where it converges. C ₁ is a mutually coincident cross point where the electron beams R and B are both focused before entering the electron lens L, and the points C _G and C ₁ both exist on the axis of the electron lens L.

The distance between these points C _G and C ₁ is the distance between the electron lens L
It is based on the aberration of

As shown in Figure 4, cathode K _B and
Since K _R is arranged at an angle with respect to the axis of the electron lens L, two of the three electron beams R, G, and B are focused at the cross point C ₁ and mutually Together with the electron beam G which intersects and focuses at a point C _G different from this point C ₁ , the three electron beams are narrowed down by an electron lens L and focused on the screen S, and at the same time three electron beams are concentrated at the point S ₁ .

FIG. 5 shows another embodiment of the present invention, in which the present invention is applied to a multistage focusing type electron gun having a front stage lens. In the figure, the same reference numerals as in FIG. 4 indicate the same or corresponding parts. However, the electron beam emitting cathodes K _R , K _G , K _B are arranged so that the electron beams are emitted in parallel to each other.

G ₃ and G ₄ are electrodes, and the supply voltage Ef is between electrode G ₃ and
At _G5 , a supply voltage Eb is applied to electrodes _G4 and _G6 . Further, the final stage electron lens L has electrodes G ₄ , G ₅ ,
Consists of G ₆ . L _R , L _G , L _B are electrodes G ₃ ,
Three electron beams R, G, composed of G ₄
This is a front-stage electron lens that deflects B individually. These front-stage electron lenses L _R , L _G , and L _B act as if the electron beam incident on the final-stage electron lens L does not actually have a focusing point on the axis of the lens L, even though the electron beam does not actually have a focusing point before entering the final stage electron lens L. This is an electron lens for creating a state similar to that of an emitted electron beam, that is, the same state as the electron beam just before it enters the electron lens shown in FIG.

FIG. 6 is a diagram showing a virtual convergence point created from the relationship between the electron lens and the electron beam in the embodiment shown in FIG. 5. _C10 is a point on the axis of the lens L where the electron beams _R and _B deflected by the electron lenses L R and L B are focused on a virtual point on the cathode side and cross each other. C _GO is a virtual focusing point where the electron beam G deflected by the electron lens L _G is temporarily focused on the cathode side.

In this way, the electron beams R, G, and B emitted from the virtual points C ₁₀ and C _GO are focused by the electron lens L formed by the electrodes G ₄ , G ₅ , and G ₆ , and are focused at the point S ₁ on the screen S.
Focus and concentrate at the same time.

In a bipotential type electron gun as shown in Fig. 4, even if the cathodes are arranged so that the electron beams are emitted in parallel to each other, the external magnetic field can be set at the position of electrode _G5 and the same effect as in the multistage focusing type can be obtained. To,
It is possible to bend the electron beam with a magnetic field and focus it onto a screen with a single electron lens.

Further, in the above embodiment, an in-line type electron gun has been described, but a delta type electron gun can also have similar effects if designed as described below. In other words, since the arrangement of each electron beam in the delta electron gun is rotationally symmetrical with respect to the central axis of the common electron lens in the final stage, the virtual convergence point of the three electron beams is located in the final stage electron lens. The design may be made so that they match regardless of the aberrations.

Further, in the above embodiment, an electron gun for a color cathode ray tube was described, but a high-intensity tube with high current was created as a plurality of multi-beam type electron guns using an electron gun for a monochrome tube, and the present invention was applied to this. A similar effect can be obtained.

As described above, according to the present invention, the focus voltage and the static convergence are in a dependent relationship with each other, so that the focus optimum voltage and the static convergence optimum voltage can be matched, and the second
This has the effect that optimum static convergence can be obtained without adding a high voltage for static convergence.

[Brief explanation of drawings]

Figures 1 and 2 are diagrams of the principle of a conventional in-line type electron gun, Figure 3 is a diagram of the basic principle of movement of an electron beam for guiding the electron gun of the present invention, and Figure 4 is a diagram of an embodiment of the present invention. Diagram of electron beam traveling principle, Figures 5 and 6
The figure is a diagram showing the principle of movement of an electron beam in another embodiment of the present invention. In the figure, K _B , K _G , K _B are cathodes, L is the final stage electron lens, R, G, B are electron beams,
C _O , C _G , C ₁ , C _GO , C ₁₀ are focal points or virtual focal points. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] 1. A plurality of cathodes that each emit an electron beam, a single final-stage electron lens for the plurality of electron beams for narrowing down the electron beams from these cathodes, and this final-stage electron lens. and a control electrode and an acceleration electrode disposed between the plurality of cathodes, and two or more of the cathodes that are not disposed on the axis of the final stage electron lens are aligned with the axis of the final stage electron lens. The focal point of the electron beam from the cathode, which is tilted with respect to the axis of the final stage electron lens when viewed from the final stage electron lens, is aligned with a point on the axis of the final stage electron lens. An electron gun for a color picture tube, characterized in that the electron gun is configured to 2. A plurality of cathodes that each emit an electron beam, a single final-stage electron lens for the plurality of electron beams for focusing the electron beams from these cathodes, and a combination of the final-stage electron lens and the plurality of cathodes. a control electrode, an acceleration electrode, and a plurality of front-stage electron lenses corresponding to the plurality of electron beams arranged between the two or more cathodes that are not arranged on the axis of the final-stage electron lens; An electron gun for a color picture tube, characterized in that an apparent focal point of the electron beam when viewed from the final stage electron lens is made to coincide with a point on the axis of the final stage electron lens by the first stage electron lens. .