JPS58147943A - Electron gun - Google Patents

Abstract

PURPOSE:To reduce spherical aberration further by mechanically integrating the third grid and the fifth grid mutually and supporting the fourth grid through a window section using an insulating support rod in such a condition that the large diameter section of the fourth grid is arranged inside the fifth grid. CONSTITUTION:The fifth grid G5 and the third grid G3 are integrated mechanically and the fifth grid G5 is simultaneously retained by the support of the third grid G3 onto an insulating support rod without being supported by the insulating support rod 4 of the fifth grid 5. Besides, the fourth grid G4 is supported by the linear insulating support rod 4 through the window section 3 of the extended section 2 of the fifth grid together with the third, second, and first grids G3, G2, and G1. For this reason, the distance between the outside surfaces of the both opposed insulating support rods 4 can be made smaller than the diameter D3 of the fifth grid G5. As a result, the diameter D3 of the fifth grid G5 can be increased until the diameter sufficiently approaches the inner diameter D4 of a neck section 6 and the spherical aberration of the main electronic lens can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a unipotential electron gun with low aberrations.

Unipotential electron guns are used in color picture tubes, projector tubes, etc. because they have excellent blooming characteristics in high current ranges. Unibotense,
The Tor type electron gun has a cathode I, a first grid 1-' (control electrode) G1, a second grid (acceleration electrode) G2, a third grid (first anode electrode) G3, and a fourth grid (focusing electrode). They are arranged in the order of 04 and 5th crit-(second anode electrode) G5 and consist of ζ. In order to reduce the spot diameter of the electron beam incident on the phosphor screen in the electron gun of It is important to reduce the spherical aberration of the main electron lens as much as possible.To do this, it is necessary to
It is good to have a large deviation from the diameter of 1, but in order to increase the diameter by 1, the inner diameter of the neck of the cathode ray tube housing the electron gun must be increased. (The deflection sensitivity of the deflection yoke decreases.)

On the other hand, as shown in Figure 1, the unipotential lens is
A deceleration lens (Lens 1) consisting of the third glyph 1' G z and the fourth glyph C4 and the fourth glyph FG
Accelerating lens (Lens) consisting of 4th and 5th Gliso [G5
2), then the smell ′ζ is
Since the electron lens action areas can be separated from each other, the aberration coefficient of the main electron lens thread can be considered separately for the deceleration lens (Lens 1 ) and the acceleration lens (Lens 2).

It is known that this aberration coefficient is small for the deceleration lens and large for the acceleration lens. 5. If the amount of aberration of the accelerating lens is improved and the accelerating lens is further shifted to a lens with a weaker lens effect, the amount of aberration of the entire unipotency toll lens can be improved.

FIG. 2 shows an electron gun with low aberrations proposed in Japanese Patent Application No. 155881/1983 based on the fact that the aberration coefficient of the main electron lens thread mentioned above can be considered and divided into the deceleration lens and the acceleration lens. In this electron gun, a cathode K, a first grid G+, a second grid G2, a third grid 03, a fourth grid G4, and a fifth grid G5 are arranged in sequence, and an anode voltage of 6 is applied, a focus voltage V is applied to the fourth grid G4, and a unipotential type main electron lens system is constructed by the third grid G3 to the fifth grid G5. , ": The electron lens l aperture I)1 of the front stage deceleration lens (Lensl) constituting the electron lens thread (i.e. the aperture of each opposing end of the third grid G3 and the fourth crit G4) is replaced with the rear stage acceleration lens (Lens2). ) of the electron lens throttle diameter D2 (i.e., the fourth grid G4 and the fifth grid G5)
diameter of each opposing end) is selected to be smaller than L7 (D2 <01)
, and the length of the fourth grid G4 is 7! l+ +7!2)
The front and 1 & stage lenses (Lensl) and (1, e
The length is selected so that the electron lens action area of ns2) can be separated, and the aberration coefficient of the main electron lens group is made small.

Conventionally, each of the first to fifth grids G5 is generally supported by a common insulating support rod (dW beep ink glass).Therefore, the electron gun supported by the insulating support rod is placed inside the neck. If accommodated in
To allow for insulated support rod valves, there is a limit to the size of the grid L] diameter. For example, when the grid is housed in a neck with an inner diameter of 29 tsuru, the effective inner diameter of the grid is 18i/14+u culm. In such a situation, the electron gun shown in FIG. 2 was designed to reduce the aberration coefficient by reducing the aperture (4Di) of the deceleration lens (Lens 1).

The electron gun to which the present invention is applied employs a configuration in which spherical aberration is further reduced in view of the above points.

Hereinafter, the electron gun according to the present invention will be explained.

Fig. 3 does not show a basic example, but is a unipotential type electron gun in which cathode I (first grid FG1 to fifth grid G5 are arranged in sequence, and voltage is applied to third grid FG3 and fifth grid G5). For example, anode voltage ■8 is obtained,
A focus salt 1+h V p which is sufficiently lower than this is given to the fourth grid G1, and a unipotential type 4-electron lens group is formed by the third grid Ga and the fifth grid G5, and is composed of -C.

Also in the present invention, the third grid G3 and the fourth grid G3
4 and °ζ deceleration type front-stage electron lens (1, ens
1) is constructed, and the fourth grid G4 and the fifth grid G.
ens 2) is configured, but the previous stage electronic 7s (L
ens l) and the subsequent electronic lens (Lens 2
) and! 1. The fourth
Set the length l of Griso 1'G4, and change the electron lens diameter of the front electron lens (Lensl) to the rear electron lens (Lensl).
The aperture of the fifth grid G6 is selected to be smaller than the aperture of the fourth grid G4 in the 1st & stage electron lens (Lens2). That is, the third grid G of the fourth grid G4
The diameter D2 on the fifth grid side of the fourth grid G4 is made larger than the diameter D1 on the third side, and the diameter D of the fifth grid G5 is further increased.
Increase 3 (Ds < D2 < 1) 3). Also,
The length of the fourth crit' G 4 is such that the front electron lens (Lens I) and the rear electron lens (Lens 2) have their electron lens action areas separated by tJ. (
I! 1+J2) is the diameter of the third grid G3, therefore the fourth
The diameter is selected to be at least 1.5 times the diameter D1 of the small diameter portion of the grid G4, that is, 1≧1.5rl+. With this configuration, the amount of aberration of the child lens ('Lens 2) in the latter stage of the acceleration type is improved, and the overall aberration of the -1 electron lens group is further improved.

FIG. 6 is a curve diagram comparing the spherical aberration coefficients of an electron gun according to the present invention and a conventional electron gun.

In the same figure, the vertical axis of ζ represents the quantity g3 related to the spherical aberration coefficient (this is shown in the relational expression for the aberration coefficient described above),
The focal length f1 on the object point (crossover point) side is plotted on the horizontal axis. Curve (1) is the third Grisotho G3 shown in FIG.
Each diameter of the fourth grid G< and the fifth grid G5 is tL
and the length A of the fourth gliso F' G 4 = 21.
This is the case of a general unipotential electron gun with a zero angle. The curve (U) is the latter electron lens (
Lens2> mouth 14D2 (5th grid G5 and 4th grid
The apertures on the 5th grid side of grid G4 are the same diameter) are selected from the [1 diameter D1 of the front stage electronic lens (Lensl), D+=13.81th, I)2
= 16.4m, 12 = 28.1m
m.

This is the case where 62=IOmm. Curve (III A
), (■8), and (m c ) are β-□28.1 mm and 33 mm, respectively, for the unipotential electron gun shown in Figure 3.
．． This is the case where 1 ho, 38.1 iris 1, (however, I)
+=13.8 Tomohei, D 2-16.4mm, l) 3-
22. (b+i,, (12-10+u constant).

In addition, please refer to FIG. 7 for the relational expression of the aberration coefficient. The amount of aberration (Heems Bosoto half 1ψ at the imaging plane (1)) Δr is the spherical aberration coefficient C5, the magnification of the lens M, and the half angle of the maximum divergence angle from the Heems glue point (object point) C0.
Then, Δr−MCSα. j It is possible to obtain. And the C3 given in Figure 6 is 1.

g3°CSO/ f2 Δr2(Lα−1勺C3 However, , is the focal point on the image side!i'L!l1lI, and L is the distance from the object point to the imaging plane.

As is clear from Fig. 6 above, the electron gun shown in Fig. 3 clearly shows a better aberration coefficient than the conventional electron gun in Fig. 5, with an aberration coefficient of about 15% to 20%. It has been improved. In addition, in the present invention, "ζ", the fourth Gliso FC4 is replaced with the fifth Gliso FC4.
It has also been confirmed through experiments that the amount of aberration hardly changes even if the lens is placed in Grid C5 and assembled together.

Next, a specific configuration of the present invention will be explained with reference to FIGS. 8 and 9. In this case as well, the first grid G1 to the fifth grid G5 are sequentially arranged coaxially, but in particular, the fifth grid 1'G5 having the diameter D3 and the fifth grid G5 having the diameter D3 are arranged sequentially on the same axis.
The third grid G3 and the fifth grid G3 have a mechanically integrated structure (=integral molding, or the third grid G3 and the fifth grid t"
c s is integrated by welding etc.), and the 4th clid G
-+ is arranged inside the integrated fifth Gliso F' G s.

In this case, an extension part (2
), the windows (3) are located at opposite positions.
form. Therefore, this extension part (2) substantially corresponds to a single part that electrically connects the fifth grid G5 and the third grid G3. and a fourth gliso F' consisting of a small diameter part having a diameter D1 and a large diameter part having a diameter of [1].
The grid G4 is arranged so that its large diameter part can fit into the substantial fifth grid G5, and its small diameter part faces the window part (3) so as to face the third grid G3. This fourth grid'
A front-stage electron lens group (Lensl) is formed by the small diameter part of G-1 and the third grid G3, and the fourth grid G4
A rear-stage electronic lens system (Lens2) is formed by the large diameter portion of the lens and the fifth clino FG6. In this state, connect the first grid Gs to the fourth grid G4 with a common insulating support rod (
4). The fourth grid G4 is supported at the portion facing the window (3). In addition, the fifth grid G
At the rear end of 5 is a shield plate (5) for the Kesotar shield.
LJ is established. Therefore, the distance 13 between the fourth grid G1 and the shield (5) is the same as that between the fourth grid G1 and the shield J
vllfil in which no electronic lens is configured between h and (5)
l (for example, I!3/D3 and 0.57). The electron gun configured in this way has a neck part (6) of the cathode ray tube body.
placed within. Gogode, 5th Griso I” G 6 L
l (D3 is D when the inner diameter of the neck part (6) is D4)
4 >D3 >0.65D4 (η).

According to this configuration, the fifth clitoris G5 is connected to the third glisso IG.
3 and is not supported by the insulating support rod (7I), the r1 diameter T' of the fifth crit G5
J3 inside the neck part (6)? 4 D 4 NiFr −
j (can be made larger at the end. For this reason, in the latter stage electronic lens system (Lens 2), the fifth gliso f" Is
5, i41) 3 can be made larger than the aperture D2 of the fourth grid G4, and the spherical aberration of the main electron lens thread can be further reduced without changing the diameter D4 of the neck part (6). .

FIG. 11 shows the amount of current (mA) between the electron gun according to the present invention and the conventional unipotential electron gun shown in FIG.
It is a curve diagram showing the relationship between the average diameter (mm) of the beam spot on the fluorescent surface and the average diameter (mm) of the beam spot on the fluorescent surface. In the figure, curve (IV) is the conventional electron gun, and curve (V) is the electron gun of the present invention. This first
As is clear from FIG. 1, the beam spot is greatly improved in the entire current range.

Incidentally, an electron gun in which the subsequent electron lens (Lens 2) is an electric field extension type lens and the inner diameter of the final electrode is rounded is also an iJ type, and in this case as well, the spherical aberration can be made smaller.

As mentioned above, in the present invention, the electron lens diameter of the front-stage electron lens system in which the electron lens action areas are separated from each other is simply selected to be smaller than the electron lens diameter of the rear-stage electron lens system. In addition, the spherical aberration is reduced, making it suitable for application to ζ color picture tubes, projector tubes, and the like.

In particular, in the present invention, as shown in FIGS. 8 and 9, the fifth grid G5 and the third grid G3 are mechanically integrated, and the fifth grid G5 is supported by the insulating support rod (4). The fourth grid G4 is simultaneously held by the support of the insulating support rod of the third grid G3 without any problems, and the fourth grid G4 passes through the window (3) of the extension (2) of the fifth grid G3 to the third grid G3.
The second and first grids G3, G2 and G1 are supported by straight insulating support rods (4). For this reason, the distance between the outer surfaces of both opposing insulating support rods (4) is 5th gris.]
- The diameter D3 of the fifth grid G5 can be made larger than the diameter D3 of the fifth grid G5, and the diameter D3 of the fifth grid G5 can be increased until it approaches the inner diameter D4 of the neck (6), and the main electron lens system The spherical aberration can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of the main electron gun according to the present invention, with the thread part removed, Fig. 2 is a cross-sectional view showing an example of a conventional unipotential electron gun, and Fig. 3 is a cross-sectional view of the electron gun according to the present invention. 4 and 5 are cross-sectional views showing the main parts of a conventional electron gun, and FIG. 6 is a cross-sectional view showing a basic example of a gun, and FIG. FIG. 7 is an explanatory diagram for determining the relational expression of aberration coefficients, FIGS. 8 and 9 are plan views and cross-sectional views showing the longitudinal structure of the electron gun according to the present invention, and FIG. There is a curve diagram showing the relationship between the current amount and the beam spot diameter of the present invention and the conventional electron gun. K is a cathode, and G1-G5 are first to fifth crits. 3 Fig. 1, Fig. 2, 〉Mo Fig. 3, Fig. 4, ! , Distance f1 Figure 8 Figure 9 Figure 10 Current f 7F1A Procedural amendment December 27, 1982 1, Display of the incident 1982 Patent Application No. 167319 2, Title of the invention Electronic mirror 3, Make the amendment Relationship with the case Patent applicant address Tokyo Parts Co., Ltd. 6-7-35 Name 421
8) Sony Corporation Representative Director Norio Ohga 4, Agent 1-8-1 Nishi-Shinjuku, Shinjuku-ku, Tokyo (
Shinjuku Building) Tokyo (03) 343-5821 (Representative)
6. The number of inventions increased by amendment or more

Claims (1)

[Claims] In the unipotential electron gun, the diameter of the fifth grid of the fourth grid is selected to be larger than the diameter of the third grid' side, and further, the diameter of the fifth grid is selected to be larger than the diameter of the fourth grid. The third grid and the fifth grid are mechanically integrated with each other through an extension portion extending from the fifth grid by an equal diameter and having a window portion formed therein, An electron gun in which the fourth gris is supported by an insulating support rod through the window with its caliber side disposed inside the fifth clit.