JPH04160738A - Electron gun for color cathode-ray tube - Google Patents

Abstract

PURPOSE:To uniform the shape of the beam spot on a phosphor screen without damaging the beam spot of an electron beam by making a second asymmetrical electron lens into an electron lens forming a electric field common to 3 electron beams. CONSTITUTION:First asymmetrical electron lenses 20B, 20R which deflect such that a pair of side beams 6B, 6R are approached to a center beam 6G are formed on a prefocus lens portion, and second asymmetrical lenses 21B, 21R which deflect such that side beams 6B, 6R are approached to the center beam 6G similarly to the case of the main lens portion are formed similarly on the main lens so that the second asymmetrical electron lenses 21B, 21R are made into electron lenses to form an electric field common to 3 electron beam 6B, 6R, 6G. When a pair of side beams pass the insides where the aberration of the second asymmetrical electron lenses 21B, 21R is great, the aberration can be cancelled. It is thereby possible to uniform the shape of a beam spot on a phosphor screen without damaging the beam spots of the electron beams 6B, 6R and 6G.

Description

Detailed Description of the Invention [Objective of the Invention] (Industrial Application Field) The present invention relates to an electron gun for a color cathode ray tube that emits three electron beams arranged in a row passing on the same plane, and in particular, This invention relates to an electron gun for color cathode ray tubes with good concentration.

(Prior Art) Generally, a color cathode ray tube has an envelope consisting of a panel (1) and a funnel (2) integrally joined to the panel (1), as shown in FIG. 1
) A phosphor screen (3) consisting of a three-color phosphor layer that emits blue, green, and red light is formed on the inner surface, and a number of electron beam passage holes are formed inside the phosphor screen (3), facing the phosphor screen (3). A shadow mask (4) having a shape formed thereon is attached. Also, there are 3 electron beams (6B) in the neck (5) of the funnel (2).

An electron gun (7) that emits <GG) and (OR) is provided. Three electron beams (8B), (Itch), (SR
) attached to the outside of the funnel (2).
8) Deflected by the horizontal and vertical deflection magnetic fields generated by
The phosphor screen (
3) is scanned horizontally and vertically to display a color image on this phosphor screen (3).

Currently, among such color cathode ray tubes, there is a color cathode ray tube equipped with an in-line electron gun that emits three electron beams arranged in a row, consisting of a center beam and a pair of side beams, which pass on the same horizontal plane from the electron gun (7). Widely used.

Figure 3 shows a QPF (Quadra Potential), which is often used as an in-line electron gun.
Focus) type electron gun. This electron gun has three cathodes (KB), (KG), (KR
), its respective cathodes (KB), (KG), (K
The first to sixth grids (Gl) to (Gl) are arranged sequentially from the three heaters (H) inserted inside R) and the cathodes (KB), (KG), and (KR) toward the phosphor screen. G6). The first to sixth grids (G1) to (G6) have three electrodes corresponding to three cathodes (KB), (KG), and (KR), respectively.
Electron beam passing holes are provided. And the cathode (KB).

(KG), (KR) and this cathode (KB)
, (Kc), (KR) adjacent to the first and second
A triode is formed by the grids (cl), (G2), and the next third, fourth, and fifth grids (G3), (
G4), (G5), three electron beams arranged in a row are emitted from the triode part (6B), (6c),
(eh) is formed, and furthermore, the fifth and sixth grids (G5) and (G8
), three electron beams (6B), (8G), arranged in a row are pre-focused by the pre-focus lens section.
The structure is such that a main lens part is formed which finally focuses and concentrates the (OR) onto the phosphor screen.

Three electron beams (6
B), (6G), and (6R), the center beam (6G) travels straight on the gun axis (ZG) from the cathode (KG) through the prefocus lens section and the main lens section, but a pair of side beams Beam (6B), (O
Regarding R), the path from each cathode (KB), (KR) to the main lens section passes over each gun axis (ZB), (ZR), but the fifth grid (G5) (7) and the sixth grid (G
A pair of side beam passing holes (10b) on the 6) side, (
10c), a pair of side beam passing holes (llb) on the fifth grid (G5) side of the sixth grid (G6)
, (lie) is eccentric outwards, and a pair of side beams (
Since the main lens part for 6B), (6R) is an asymmetric electron lens (12B), (12R) eccentric to the outside, a pair of side beams (6B), (6R) are used.
R) is the center beam (8
G) is deflected to the side and concentrated on the phosphor screen.

Although FIG. 3 shows an electron gun with a pair of decentered side beam passing holes as a means for forming an asymmetric electron lens, as a means for forming an asymmetric electron lens,
The 6th grid is connected to the pair of side beam passing holes in the 5th grid.
It can also be formed by inwardly sloping a pair of side beam passage holes on the fifth grid side of the grid.

By the way, as described above, by decentering or tilting the pair of side beam passing holes to form an asymmetric electron lens, three electron beams (6B) and (6G) can be generated.

The means for concentrating (6R) on a phosphor screen cannot achieve the intended purpose unless the potential difference between the electrodes forming the asymmetric electron lens is accurate, and the voltage applied between the electrodes is inaccurate. In this case, there is a problem that the concentration on the phosphor screen is shifted.

In particular, recent color cathode ray tubes are of the preset type, which undergoes final adjustment before being installed in the receiver, and is installed without any adjustment when the receiver is installed. If the voltage applied to the fifth grid is inaccurate when setting the operating conditions for the electron gun, it will have to be readjusted after it is installed in the receiver.

Therefore, Japanese Unexamined Patent Publication No. 55-53853 discloses an electron gun shown in FIG. 4 as a means to reduce the concentration deviation on the phosphor screen that occurs when the voltage applied between the electrodes is inaccurate. There is.

This electron gun is of the same QPF type as the electron gun shown in FIG. 3, and is particularly different from the electron gun shown in FIG.
, (14c), a pair of side beam passage holes (1) on the fourth grid (G4) side of the fifth grid (G5)
5b) and (15c) are eccentric to the outside, and a first asymmetric electron lens (
16B), (16R), and a pair of side beam passage holes (10b), (10c) on the sixth grid (G6) side of the fifth grid (G5).
, the fifth grid (G5) of the sixth grid (G6)
) side beam passing holes (llb), (l
lc) to the outside and attach a pair of side beams (6B
), (6R) are configured to form second asymmetric electron lenses (17B), (17R) that are eccentric to the outside.

Therefore, in this electron gun, the three electron beams (8B), (6G), (81?) in the -row arrangement are connected to the cathode (KG) with respect to the center beam (6G) as in the electron gun shown in FIG. ) from the gun axis (ZC) and passes through the prefocus lens section and the main lens section, but for the pair of side beams (6B) and (OR>), the prefocus passes from each cathode (KB) and (KR). It passes over each gun axis (ZB) and (Zl?) up to the lens section, but in the prefocus lens section, it passes over the fourth grid (G4?).
), a pair of side beam passing holes (14b), (14
c) of the fourth grid (G5) of the fifth grid (G5)
A pair of side beam passing holes (15b) on the 4) side, (
15c) is eccentric to the outside, and a pair of side beams (6B)
, (6R), a first asymmetric electron lens (16B) eccentric to the outside in the prefocus lens section.

(18R) is formed, so a pair of side beams (8R) are formed.
B) and (8R) are each deflected to the center beam (6G) side by this prefocus lens section. Furthermore, in the main lens part, a pair of side beam passing holes (10b) on the sixth grid (C6) side of the fifth grid (G5) are provided.
.

A pair of side beam passage holes (llb) on the fifth grid (G5) side of the sixth grid (G6) with respect to (10c),
(lle) is eccentric to the outside, and a pair of side beams (6B
), (6R) with a second lens eccentrically located outwardly from the main lens portion.
Since asymmetric electron lenses (17B), (17R) are formed, -pair of side beams (6B), (OR
) are each further deflected to the center beam (6G) side by this main lens section and concentrated on the phosphor screen.

Therefore, in this electron gun as well, the first asymmetric electron lenses (16B) and (16R) formed between the fourth and fifth grids (G4) and (G5) and the fifth and sixth grids (G5), The second asymmetric electron lenses (17B) and (17R) formed between (C8) are both influenced by the potential difference between the electrodes. However, in this electron gun, when the voltage applied to the fifth grid (G5) decreases, the deflection effect of the first asymmetric electron lenses (16B) and (16R) becomes smaller, but at the same time the deflection effect of the second asymmetric electron lens (17B) decreases.
) and (171?) become relatively large. Conversely, when the voltage applied to the fifth grid (G5) increases, the deflection effect of the first asymmetric electron lens (leB), (16R) increases, but at the same time the deflection effect of the second asymmetric electron lens (16R) increases.
17B) and (17R) are relatively small, and compared to the electron gun shown in Figure 2, the influence of changes in the voltage applied to the fifth grid (G5) on the concentration of the electron beam is reduced. Can be made smaller. Therefore, by making the final adjustment before assembling the color cathode ray tube into the receiver, it is possible to make no adjustment at the time of assembling the receiver.

However, in this electron gun, a pair of side beams (6B)
, (OR) is the second asymmetric electron lens (17B)
.

Since the beam spot on the phosphor screen is degraded because it passes through the inside of the lens with large aberration (coma aberration) of (17R), the beam spot (18B) and (18G ), (18
The blur (19) of R) becomes larger.

(Problem to be Solved by the Invention) As described above, a QPF type electron gun is used as an in-line color cathode ray tube electron gun that emits three electron beams arranged in a row, consisting of a center beam and a pair of side beams passing on the same horizontal plane. is often used. However, this electron gun has a structure in which an asymmetrical electron lens is formed in the main lens part for the pair of side beams in order to concentrate the three electron beams on the phosphor screen.
If the potential difference between the electrodes forming the asymmetric electron lens is not accurate, there is a problem that the concentration of the three electron beams on the phosphor screen will be shifted.

In order to solve the problem of this QPP type electron gun, a first asymmetric electron lens is formed in the prefocus lens part for a pair of side beams, and a second asymmetric electron lens is formed in the main lens part for a pair of side beams. As a structure for forming an asymmetric electron lens, there is an electron gun that reduces the influence of the potential difference between electrodes.

However, in the electron gun having the first and second asymmetric electron lenses, the pair of side beams passes through the inside of the second asymmetric electron lens, which has large aberrations, so that the beam spot on the phosphor screen is degraded. There is a problem that blurring of the beam spot on the phosphor screen increases.

This invention has been made to solve the above problems, and includes an electron gun that emits three electron beams arranged in a row, consisting of a center beam and a pair of side beams passing on the same plane. An object of the present invention is to construct an electron gun that reduces the concentration deviation of an electron beam and makes the beam spot shape uniform on a phosphor screen without impairing the spot size of the electron beam.

[Structure of the Invention] (Means for Solving the Problems) The above-mentioned method has a plurality of electrodes having an integral structure in which three cathodes arranged in a row and three electron beam passing holes corresponding to the cathodes are formed. A triode is formed by a cathode and a plurality of electrodes successively adjacent to the cathode, and a center beam and a pair of side beams are emitted from the triode by the plurality of electrodes successively adjacent to the triode. A prefocus lens section that pre-focuses the 3m electron beam arranged in a row and a main lens section that finally focuses the three electron beams pre-focused by the prefocus lens section are formed, and the prefocus lens section is provided with the pair of above-mentioned electron beams. A first asymmetric electron lens that deflects the side beams so as to approach the center beam is formed, and a second asymmetric electron lens that similarly deflects the pair of side beams so as to approach the center beam is formed in the main lens portion. In the thus formed electron gun for a color cathode ray tube, the second asymmetric electron lens is an electron lens that forms a common electric field for the three electron beams.

(Function) As described above, the first beam deflects the pair of side beams closer to the center beam in the prefocus lens section.
A second asymmetric electron lens is formed in the main lens portion to deflect the pair of side beams closer to the center beam, and the second asymmetric electron lens deflects the three electron beams. Assuming that the electron lenses form a common electric field, the pair of side beams deflected by the first asymmetric electron lens to approach the center beam pass through the inside of the second asymmetric electron lens, which has large aberrations; The second asymmetric electron lens is a large-diameter electron lens that forms a common electric field for the three electron beams, so the aberration can be canceled and the beam spot of the electron beam can be fixed without damaging the phosphor screen. The upper beam spot shape can be made uniform.

(Example) Hereinafter, the present invention will be described based on an example with reference to the drawings.

FIG. 1 shows an embodiment of a QPP type electron gun which emits three electron beams arranged in a row passing on the same plane. This electron gun has three cathodes (KB) arranged in a -row, (
KG), (KR), each cathode (KB),
(KG).

Three heaters ()I) inserted inside (KR) and the above cathodes (KB), (KG), (KR)
The first to sixth grids (Gl) to (
G6), and its first to sixth grids (CI
) to (G6) each have 3 cathodes (KB)
Three electron beam passing holes corresponding to , (KG) and (KR) are formed. And the cathode (KI3
), (KG), (KR) and this cathode (
KB), (KG), (KR)
, the second grid (Gl), (02) form a triode, and the third, fourth and fifth grids (G3)
, (G4), (G5), three electron beams arranged in a row are emitted from the triode (6B), (6G)
, (OR) is formed, and the fifth and sixth grids (G5), (
G6), three electron beams (6B), (6G) arranged in a row are pre-focused by a pre-focus lens section.

The structure is such that a main lens part is formed which finally focuses (6R) on the phosphor screen.

Furthermore, in this electron gun, the first to sixth grids (
Among the three electron beam passing holes formed in each grid (G1) to (G6), the center beam passing hole is
) to (G6) are also coaxial, and the first, second, third, and fourth grids (Gl) 6 (G2), (G3), (G4) are also coaxial with the pair of side beam passage holes.
) and the 6th grid (G6) of the 5th grid (G5)
The electron beam passage holes on the side are coaxial, but the fifth grid (G5) and the sixth grid (G6
) side beam passing holes (15b), (1
5c) is a pair of side beam passage holes (14b) of the fourth grid (G4).

(14C), and a pair of side beams (6B), an asymmetrical electron lens (20B) eccentric to the outside of the prefocus lens part for (6R),
(2OR) (first asymmetric electron lens). In addition, a pair of side beam passage holes (llb) on the fifth grid (G5) side of the sixth grid (G6)
.

(lie) is also the 6th grid (G5) of the 5th grid (G5).
A pair of side beam passing holes (fob) on the G6) side,
A pair of side beams (6B) eccentrically outward relative to (10c).

Asymmetric electron lenses (21B) and (21R) (second asymmetric electron lenses) eccentric to the outside are formed in the main lens portion for (6R).

Moreover, in this electron gun, the sixth grid (G6)
The electron beam passage hole (llb) on the fifth grid (G5) side
), the burring (22) constituting (llc) is
The burring is formed shorter than the burring constituting the electron beam passage hole on the fifth grid side of the sixth grid of the conventional electron gun shown in FIG.
, (6G), (6R) In addition to independent electron lenses, 3 electron beams (6B), (6G), (6R)
The structure forms a common large-diameter electron lens.

Therefore, in this electron gun, three electron beams (6B) arranged in a row are emitted from the three cathodes (KB), (KG), (KR) arranged in a row through the triode part.
(6G), (SR) is center beam (6G)
The lens travels straight on the gun axis (ZG) from the cathode (KG) through the prefocus lens section and the main lens section. However, a pair of side beams (6B), (6R
), each gun shaft (ZB), (Z
R), but in the prefocus lens section, the pair of side beam passing holes (14b) of the fourth grid (G4)
, the fourth of the fifth grid (G5) for (14c)
A pair of side beam passage holes (15) on the grid (G4) side
b), (15c) are eccentric to the outside, and a first asymmetric electron lens (20
B).

(20R) is formed, so a pair of side beams (6
B) and ([iR) are each deflected to the center beam (6G) side by this prefocus lens section. Furthermore, in the main lens part, a pair of side beam passage holes (fo
b) A pair of side beam passage holes on the fifth grid (G5) side of the sixth grid (G6) with respect to (10c)
llb).

(llc) is eccentric to the outside, and a pair of side beams (6B
), (OR) are formed with second asymmetric electron lenses (21B), (21R) eccentric to the outside, so that a pair of side beams (6B), (
6R) are each further deflected to the center beam (6G) side by this main lens section and concentrated on the phosphor screen.

Furthermore, when the pair of side beams (6B) and (6R) pass through the main lens section, they are distorted because they pass inside the second asymmetrical electron lens (21B) and (21R), which have large aberrations; , 3 electron beams (6B)
, (8G).

(6R) Since it passes through a common large-diameter electron lens, its distortion can be canceled.

Therefore, with this electron gun, it is possible to reduce the concentration deviation on the phosphor screen, and to make the beam spot shape on the phosphor screen uniform without impairing the spot size of the electron beam.

[Effects of the Invention] A prefocus lens section that prefocuses the three electron beams arranged in a row consisting of a center beam and a pair of side beams emitted from the triode section has a second section that deflects the pair of side beams so as to approach the center beam. 1 asymmetric electron is formed, and the pre-focused 3 electron beams arranged in a row are finally focused and concentrated in the main lens part. Similarly, a second asymmetric electron lens deflects a pair of side beams so as to approach the center beam. In the electron gun where
Assuming that the second asymmetric electron lens is an electron lens that forms a common electric field for the three electron beams, the pair of side beams deflected by the first asymmetric electron lens to approach the center beam are The second asymmetric electron lens passes through the inside of the asymmetric electron lens with large aberrations, but the aberration can be canceled by the large-diameter electron lens that forms a common electric field for the three electron beams. The shape of the beam spot on the phosphor screen can be made uniform without damaging the beam spot.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of a QPP type electron gun which is an embodiment of the present invention, FIG. 2 is a diagram showing the configuration of a color cathode ray tube, and FIG. 3 is a diagram showing the configuration of a conventional QPF type electron gun. Fourth
The figure shows the configuration of an improved conventional QPF type electron gun. 8B, 61? ...Pair of side beams 6G...Center beams 10b, 10c...Pair of side beam passage holes 11b, llc on the sixth grid side of the fifth grid...Pair of side beam passage holes on the sixth grid 14b, 14c... A pair of side beam passing holes 15b, 15c of the fourth grid... A pair of side beam passing holes 20B, 20R on the fourth grid side of the fifth grid... First asymmetric electron lens 21B ,
21R...Second asymmetrical electron lens 22...Burring Gl...First grid G2...Second grid G3...Third grid 64...Fourth grid G5...Fifth grid G6... 6th grid H... Heater KB, KG, KR... Cathode agent Patent attorney Norio Ogo 20R21R 2O321s KB, KG, KB n7-F Fig. 1 20B, 20R
l + IfI+＞*, ti, L〉x゛Fig. 2

Claims (1)

[Scope of Claims] It has a plurality of electrodes having an integral structure in which three cathodes are arranged in a row and three electron beam passing holes corresponding to the cathodes are formed, and the electrodes are adjacent to the cathodes and the cathodes in sequence. A triode is formed by a plurality of electrodes, and a plurality of electrodes successively adjacent to this triode prepare for preparing three electron beams arranged in a row, consisting of a center beam and a pair of side beams, emitted from the triode. A prefocus lens section for focusing and a main lens section for finally converging and concentrating the three electron beams arranged in a row prefocused by the prefocus lens section are formed, and the pair of side beams are directed to the prefocus lens section. A first asymmetric electron lens is formed to deflect the pair of side beams closer to the center beam, and a second asymmetric electron lens is formed in the main lens portion to deflect the pair of side beams closer to the center beam. An electron gun for a color cathode ray tube, characterized in that the second asymmetric electron lens is an electron lens that forms a common electric field for the three electron beams.