JPS6310440A - Electron gun device - Google Patents

Abstract

PURPOSE:To simplify the manufacture of the title device and to improve its accuracy, by setting the center axes of electron beam transmitting apertures of electrodes composing the pri-stage electron lens parallel to each other. CONSTITUTION:As for electron beam transmitting apertures of a first to a third grids G1 to G3 up to an end plate 31 on the pri-stage side, the axes of transmitting apertures h1R, h2R, and h31R for a side electron beam BR are on the same axis OR, while the axes of transmitting apertures h1B, h2B, and h31B for the other side electron beam BB are on the axis OB. The axes OR and OB are inclined by a specific angle theta to an axis OG of the transmitting apertures h1G, h2G, and h31G for the central electron beam BG, and they are crossed each other at a specific point on the axis OG. Although the axis of the transmitting apertures h3G and h4G of the central beam B are on the axis OG, the transmitting apertures h3R and h4R of the side beam BR are on another axis OR' parallel to the axis OG, while the transmitting apertures h3B and h4B of the other side electron beam BB are arranged on an axis OB' parallel to the axis OG and the axes OB' and OR' are symmetric with the respect to the axis OG.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electron gun device suitable for use in cathode ray tubes such as color television picture tubes.

[Summary of the invention]

The present invention provides an electron gun device that takes out a plurality of beams, and in particular, a main electron lens for these beams, a front-stage electron lens action area provided for each beam, and a rear-stage electron lens action area provided in common for the plurality of beams. In the electron gun device, the central axes of the electron beam transmission apertures of the electrodes constituting the front-stage electron lens for each beam are set parallel to each other, thereby simplifying manufacturing and improving precision.

[Conventional technology]

For example, as shown in FIG. 6, cathodes KR, KG, and KB are provided corresponding to red, green, and blue in an electron gun device used in a color television picture tube or the like. 2nd grid G2, 3rd grid G
3. The fourth grid G4 and the fifth grid G5 are arranged,
For example, cathode K (KR, KG, KB) and the first to third
A so-called double-beam single electron gun in which a cathode prefocus electron lens is formed by the grids G1 to G3, and a unipotential type main electron lens is formed by the third grid G3, the fourth grid G4, and the fifth grid G5. There is a device.

In this case, the electron beams from the cathodes KR and 8 intersect approximately at the center of the main electron lens at a position that satisfies the Braunhoffer condition, that is, provides a condition where the coma aberration becomes zero. A convergence means C constituted, for example, by an electrostatic deflection plate is provided downstream of the fifth grid G5, and thereby the electron beam B R% from each cathode KR, and from KB is provided.
BG and BE are made to converge (concentrate) on a fluorescent surface (not shown).

In an electron gun with such a configuration, by making the main electron lens common for each electron beam, the lens diameter can be increased within the limited neck diameter of the cathode ray tube, and an electron gun with small aberrations can be constructed. However, even with such a configuration, there is still a drawback that as the beam current increases, spherical aberration increases and the beam spot blooms.

Furthermore, considering a unipotential type electron lens with reference to FIG. 7, in this unipotential type electron lens system, a high voltage V^ is applied to the third grid G3 and the fifth grid G5, A main electron lens is constructed by applying a focus voltage vF to the fourth grid G4. Normally, in this type of unipotential type electron lens, the diameters of the electrodes G and G5 to which a high voltage is applied, and the focus voltage The diameter of the electrode G4 to which Vf is applied is selected to be approximately the same diameter, or the high voltage electrodes G3 and G5 are made to have a small diameter on the side facing the focus electrode G4 as shown in FIG. However, in any case, the value of - is in the range of 0.5 to 2.0, where the diameter of the focus electrode G4 is x and the length is l. has been selected.

A unipotential electron lens in which the electrodes G3 to G5 are selected to have the same diameter, as shown in Figure 7! The spherical aberration stability when the negative value is changed is calculated as shown in FIG. 9.

In this figure, the horizontal axis is the ratio f of the focal length f and the lens aperture.
/D, and the vertical axis is the spherical aberration coefficient CS! As is clear from this, let − be T and one =
In other words, for the same ζ value, the larger γ becomes, the smaller the spherical aberration coefficient Cs becomes. In practice, the lens aperture is limited by the neck diameter of the cathode ray tube body, so that at a constant focal ratio mf, the longer the length l of the electrode G4, the smaller the spherical aberration.

However, on the other hand, when γ=2.0 or more, the aberration phenomenon becomes saturated, so it is desirable to reduce the focal length f at the same lens in order to achieve smaller aberrations. However, in general, if the length l of the electrode G→, that is, γ, is made large, the focal length f cannot be made small.
This will be explained with reference to the figures. Now, in the unipotential type electron lens, this is the lens formed between the third grid G3 and the fourth grid 04 (Lens 1) and the fourth grid G3.
The lens (Lens 2) formed between the grid G4 and the fifth grid 05 will be discussed separately. The object focal lengths of each lens (Lens 1) and (Lens 2) are fl and F2, and the image focal lengths are f1' and f2.
', the object focus is Fl and F2, and the image focus is F1' and F
2' and the focal length f' are given by:

Generally, in an electronic lens system, since C>0, f'>
It becomes Q. As described above, if the length i of the electrode G→, and therefore the distance between Lens 1 and Lens 2, is increased in order to reduce the spherical aberration, IcI becomes small. Therefore, from equation (1), the composite focal length f' becomes large. Since the focal length @r' becomes large in this way, it is not possible to make l sufficiently large and f sufficiently small to reduce aberrations sufficiently, as explained with reference to FIG. Furthermore, as f becomes larger, the imaging state changes. Therefore, in order to keep f constant, that is, small when l is large, as is clear from equation (1), the image focal length f1' (or) f2' of Ltns L and Lens Z must be It is required to make it smaller. However, the distance Q between the rear-stage lens Lens 2 and the fluorescent surface S of the cathode ray tube should be such that its focal length f2' is small due to the relationship with the horizontal and vertical deflection means arranged at the base of the funnel section of the cathode ray tube. There are restrictions on Therefore, it is desired to reduce the focal length f of the lens Le'ns 1 at the front stage. As a method of reducing this focal length f1', the third grid G
Ratio between the anode voltage ■^ applied to G3 and the focus voltage vF applied to the fourth glyph G4 Applying a high voltage independent of the fifth glyph G6 to the lift G3 requires separate high voltage wiring and high voltage insulation. The problem of shielding causes considerable complexity in practical use.

In order to reduce the focal length Mf□' of the front lens system without causing such drawbacks, as shown in FIG.
The first electrode, for example, the third grid G3, and the second electrode, for example, the fourth grid G4 constitute a deceleration type front-stage electron lens (Lens I), and the second electrode (fourth grid G4) and the A subsequent electron lens (
In this configuration, in particular, the electrode G4 is arranged so that the front electron lens (Lens 1) and the rear electron lens (Lens 2) are separated from each other in the action area of each electron lens. The length l is set, and the lens aperture of the front-stage electronic lens (Lens 1) is selected to be smaller than the lens aperture of the rear-stage electronic lens (Letia 2). That is, the diameter D1 of each opposing end of the third grid G] and the fourth grid G4 is made smaller than the diameter D2 of each opposing end of the fourth grid G4 and the fifth grid G5. Further, as described above, in order to separate the electron lens action areas of the front and rear lenses from each other, the third grid G3 and the fifth grid G are inserted into the fourth grid G4.
The penetration of the electric field by G4 is caused by the penetration of the electric field by
Since the opening diameters D1 and D2 of the portions facing grids G3 and G5 are approximately equal, the length 11 of the small diameter portion and the length 12 of the large diameter portion are in the relationship of 11>01.1t>D2, and therefore The length l of the fourth grid G4 is l>f:)1 +
Choose so that the relationship is D2.

Now, FIG. 12 shows an optical system shown by a solid line when the lens diameters of the front stage and the rear stage are made equal (that is, = 1).
In Figure 0, where the image is formed above, Pa is the object point, that is, the cathode image at the crossover point of each beam by the cathode-brifocused electron lens, Pl is the virtual image by the front lens (Lens 1), That is, it shows the object point of the rear lens (Lens 2), and P2 is the object point of the lens (Lens 2) imaged on the fluorescent surface S.
). In this state, the front lens (Lens
In order to avoid a change in the imaging relationship when the aperture D1 in 1) is made smaller and its focal length r1' is made smaller, that is, in order for the image to be formed on the fluorescent surface S, the previous stage The positions of the lens (Lens 1) and the object point Po are moved by a required distance as shown by the broken line.

Considering optically how to reduce the diameter of the lens (Lens 1), the image magnification of lenses Lens 1 and Lens 2 is constant, so the image formation relationship of lens Lens 1 is reduced with the image magnification constant. become. In other words, it can be expected that the amount of aberration caused by Lens 1 will also be reduced by the reduction ratio. Specifically, the front lens Len
While reducing the aperture D1 of s1, both lenses Lan
The distance between 51 and 2 is increased, and the position of the cathode is shifted. Now, when the magnification M of the entire lens diameter is selected as M = 12, and the distance %itQ from the lens Lens 2 to the image point P2 is set to Q = sox D 2, the distance from the subsequent lens Lens 2 to the object point Pa Assuming that the distance to the lens is 0, the relationship to the aperture ratio k of the lens is as shown by the solid line and broken line in FIG. In this case, the subsequent lens (
The aperture D2 of Lens 2) is 6 fl, and in FIG. 13, the vertical axis is expressed using this aperture D2 as a unit, that is, D2-1.

Figure 14 shows the calculation result of the relationship between the magnification M of the entire lens system, M=-8, and the aberration coefficient Cs, and the curve (1
0) to (13) respectively indicate the aperture ratio k of both lenses, k=1.
The calculation results when 0.0.8.0.6.0.4 are selected are shown below. Note that the numerical values shown in parentheses for each of the curves (10) to (13) are distance values expressed in units of D2. In Figure 14, the vertical axis is the coefficient cm and D2
It is expressed as a ratio of

FIG. 15 shows curves of spherical aberration coefficients similar to those in FIG. 14, but in this case, M=-10 and Q=50×D2, and curves (20) to (24) each have a coefficient of spherical aberration of =1.0. 0.8,
This is the case of 0.6, 0.4, and 0.3.

As is clear from FIGS. 14 and 15, the smaller the aperture ratio k of the lens diameters in the front and rear stages, the smaller the aperture D1 of the lens diameter in the front stage is compared to the aperture D2 of the lens diameter in the rear stage, It can be seen that aberrations are improved.

As mentioned above, when providing a front-stage lens action area and a rear-stage lens action area that are independent of each other and reducing the aperture ratio k of the two, a lens with small spherical aberration can be constructed. Lens Lens 1 and Lens 2 formed by lens action areas
The total spherical aberration CI of the composite lens system consisting of these two
When the spherical aberration coefficients of the two lenses Lens 1 and Lens 2 are C51, C, 2, it is given by the following equation.

From this, the aberration amount Δr can be expressed as follows.

and D2, Ml and M2 are the voltages applied to each of the first and second stages and the third electrode.

From this equation (3), in order to effectively reduce the overall amount of aberration, the front lens aperture D1 and the rear lens aperture D2 must be
It can be seen that by decreasing the ratio k.

In this way two independent lenses Lens 1, Len
The main electron lens formed by combining s 2 can improve spherical aberration by selecting a small aperture ratio k, but in this lens, astigmatism and field curvature aberration are This becomes a large value. Therefore, such a composite lens system is used as a common main electron lens for a plurality of beams, for example, three, as explained in FIG. Three beams BR, BG and BB at the position where the aberration becomes zero
Even in a configuration in which the beams BR and Bs intersect, the spot sizes of the beams BR and Bs on both sides become worse.

Therefore, regarding the side beam as well, Japanese Patent Laid-Open No. 55-19
An electron gun device disclosed in Publication No. 755 was proposed. In this electron gun device, the front stage electron lens Lens l,
In other words, the main electron lens is composed of the front-stage electron lens action area and the rear-stage electron lens Lens 2 separated from this, that is, the rear-stage electron lens action area. Each beam is individually provided, and the subsequent electron lens is agitated by an electron lens with small astigmatism and curvature of field, and this is provided in common for each beam. Then, the lens aperture of each front stage is selected to be smaller than the lens aperture of the rear stage.

That is, in this electron gun device, as shown in FIG. 16, for example, the main electron lens includes a front-stage electron lens having a deceleration type pi-potential electron lens configuration, and an electron lens action region separated from the electron lens action region thereof. We explore an accelerated pi-potential electron lens configuration with . In this case, for example, cathodes KR, KG corresponding to red, green and blue
and Kg, and for each of these cathodes KR%KG and Ka, i.e. for each beam BR, B and Bg, a first grid G, %GL() and Gta, a second
Grids G 2R % 02G and G 2B s Third grids G3R5GAG and 03B are arranged in sequence, and a fourth grid G4 and a fifth grid G5 are provided in common to these grids. Each third grid G 3R of the fourth grid G4
At the end opposite to G3G and G3B, cylindrical branched electrode portions G4R, G4G, and G4B are provided corresponding to the grids G3R, GIG, and GlB, respectively.

Then, the voltage ■1 applied to the third grid G3RS03G and CIB, the voltage ■2 applied to the fourth grid G4, that is, each electrode part G4R, G4G and CF2O, and the voltage
The relationship between the voltage applied to the grid G5 and the voltage ■2<y,
<v3, and vl and ■3 are, for example, the anode voltage V)4
be selected. In this way, each electrode part G4R-, 04G, and 048 of the fourth grid G4 and the third grid G3
The deceleration pi-potential type electron lenses LenSIR1LenStes and LenStes, which constitute the main electron lens for each of the beams BR, BG, and BS, are
The fourth grid G4 and the fifth grid G5
1 in common for each beam BR, B, and Be by
1 stage acceleration type pi-potential electron lens Lens2
Configure. Here, the diameter of the end of the fourth grid G4 on the third grid side, that is, the diameter D1 of the electrode parts G4R-, 04G and G411, and the diameter D of the end of the fifth grid side.
2=D□/D 2, k<1, and the fourth
The length of the grid is selected to be greater than Dt+D2 so that the respective lens action areas of the front lenses LenstRSLensteS and 1ens1B and the rear lens Lens 2 are separated.

Then, each of the beams BR, Be, and Be is sent to a rear lens Le.
The intersection is made approximately at the center of ns 2 so as to satisfy the Braunhofer condition.

FIG. 17 shows another example, in which the subsequent electron lens Lens 2 has an extended type (extended electric field type) pi-potential electron lens configuration. That is, in this case, the rear lens Lens 2 is constituted by the fourth, fifth, and sixth grids G4 to Gε, and the third grid G3 (G3R-, G3G-, G3B
), the voltages 1 to v4 applied to the fourth grid G4, the fifth grid G5, and the sixth grid G6 are, for example, v1=V
The anode voltage is given as 4, and V2 /Vt = 0.25 ~
0.40, and the relationship of Vi/V = 0.4 to 0.6 is selected.

In this way, by configuring the main electron lens with a small-diameter front lens and a large-diameter T& stage lens, a main electron lens with small spherical aberration is constructed, and the front stage lens is configured individually for each beam. By adopting a configuration in which the rear lens is provided in common for each beam, the problem of astigmatism and field curvature for the front lens is solved, and the problem of astigmatism and image surface curvature for the rear lens is solved. By making it possible to use an electronic lens with a lens configuration with small surface curvature aberration,
Although it has a double-beam single electron gun configuration, it is a polar configuration due to astigmatism and field curvature of the side beam, and in this example, for each cathode K G and 8, the first grid Although G1as C1IG and G1B are provided individually, the second and subsequent grids are formed by a common metal electrode body, respectively, and a common second grid 02 to sixth grid G6. That is, each cathode KR,
, and for each beam from KB, the front lens of the main electron lens
Although these constitute ensxg, these Lf3n51R,
Lensxe 1 and enSlB, respectively, with the common third
Each electron beam transmission hole h provided in the front end plate of grid G3 and the front end plate of fourth grid G4: lR, h
Consists of 3Gs h3B, hoR, h4e, and h4 days. Then, each previous stage LenstR% Lenst
e s and LensiB are formed with the required relationship based on the same consideration as described above. In this case, each lens Lens1u 5LenstG-
, and the third and fourth grids G constituting Lensta.
] and each electron beam transmission hole h'JR1h3e, hts and n 4R% h4(
The i % h 4B is provided with a cylindrical circumferential side wall W formed by, for example, burring on its periphery to prevent mutual disturbance of the electric field. Each first grid G IR% G
IG % Cx is % Electron beam transmission holes are formed in the front end plates of the second grid G2 and the third grid G3, respectively, and a cathode prefocus lens is configured for each beam. Each of the electron beam transmission holes constituting the cathode/prefocus lens and the front lens has the same axis 0R1o with respect to each electron beam.
e and 08 and the axis OG for the central beam
Centering on the axis OR and 08 for both side beams
are arranged so as to be inclined at a required angle θ. In other words, the front end face plate of the third grid G3 and the fourth grid G3
Each transmission hole h3R% h I formed in the rear end face plate of 4
G, h3B and h 4R% h 4G and h4fl's circumferential side walls Ws are also set to predetermined axes 0R1OG and 0, respectively.
8, the manufacturing thereof is complicated, and problems arise in manufacturing accuracy such as setting the direction of the axis.

[Problem that the invention seeks to solve]

The present invention provides an electron gun device in which the main electron lens is separated into a front lens and a rear lens, the former lens is individually provided for each electron beam, and its aperture is larger than that of the rear lens. The aim is to solve the problems of manufacturing complexity and accuracy mentioned above.

[Means for solving problems]

In the present invention, a plurality of cathodes are provided, and a main electron lens has a front-stage electron lens action region that is individually provided on each path of an electron beam by each cathode, and a plurality of front-stage electron lens action regions that are separated from these front-stage electron lens action regions. and a rear-stage electron lens action area provided in common on the beam path, and the electron lens aperture of the electron lens system by the front-stage action area is made smaller than the electron lens aperture of the rear-stage electron lens action area. However, particularly in the present invention, the central axes of the electron beam transmission holes of the electrodes constituting the electron lens action area of the front stage on the path of each electron beam are selected to be parallel to each other, and The positions of the electron lens action areas are selected to satisfy the Braunhofer condition.

[Effect]

As described above, according to the present invention, the axes of the electron beam transmission holes constituting each lens are set parallel to each other, even though the front lens is individually provided for each electron beam. , these through-holes can be formed easily and with high precision, and even when peripheral side walls are provided around the periphery of the electron beam transmission holes constituting these front-stage lenses by, for example, burring, the axial directions of the holes are set parallel to each other. Therefore, the mutual axial spacing and axial direction settings can be performed with high precision. In addition, by selecting the front lenses for each beam in a parallel relationship in this way, for the side beams, the beams enter these front lenses from a direction that does not coincide with the front axis of the front lenses. Since the lens is selected so as to satisfy the condition of F, the problem of comatic aberration caused by misalignment of the axes of the beam and the lens can be alleviated.

〔Example〕

An example of the apparatus of the present invention will be described in detail with reference to FIGS. 1 and 2. This example is a case where the main electron lens has a unipotential configuration. In this case as well, the cathodes KR, KG and the sun corresponding to, for example, red, green and blue are provided, for example, on a horizontal plane, and these cathodes KR, KG and
and KH, the first grid G R%C; IG and GIB are disposed, followed by a common cathode for each cathode, that is, the central electron beam BG corresponding to each color, and the electron beams BR and B8 on both sides. 2nd to 6th grid 02
~G6 are arranged in sequence.

The third grid G3 includes a front side end plate (31) facing the second grid G2 and a rear side end plate (32) facing the fourth grid G4.

The fourth grid G4 has a front side end plate (41) facing the third grid G3.

The first grids GIR-, 01G and ci8 are arranged coaxially with the corresponding cathodes KR and Ks, respectively, and have an electron beam transmission hole hIR% h 13% h on each central axis.
These electron beam transmission holes hIRs
h Concentrically with IQ and hlB, electron beam transmission holes h2*s h2GSh2Bs and h31R are provided in the front side end plate (31) of the second grid G2 and the third grid G3, respectively.
,, h 31G, hila is drilled. Each of the electron beam transmission holes in the front end plate (31) of the first grid G1, second grid G2, and third grid G3 is a transmission hole h□R% h2 for one side electron beam BR.
The respective axes of Rs and hilg are on the same axis OR, and the transmission hole 8, l'1 for the other side electron beam BB is
The axes of the 2Bsh31B are on the same axis Os, and these axes OR and OB are tilted at a predetermined (7) Flltθ with the respective transmission holes hIG, )L2Gs h3LG, (7) axis oG of the central electron beam BG, They intersect at a predetermined point on the axis OG.

Then, the end plate (32
), and the front end plate (41) of the fourth grid G4
For each electron beam B R% B G-, B B electron beam transmission hole h3FL% h3() sh3B
and h4R%h4G, h4B are drilled. Here, the axes of the transmission holes h3G and h4e of the center beam BG are arranged on the axis OG, but the transmission hole ThffR5h4R for one side beam BR is arranged on the axis OG, as shown in FIG. The transmission hole h3B%h4B for the other side electron beam BH is parallel to the axis OG, and the axis 0 is symmetrical to the axis OR'.
8'. In other words, electron beam B on both sides
The axis of the cathode prefocus lens for R and Be is selected so that it has the required inclination θ with respect to the axis of the cathode prefocus lens for the central electron beam. Le
As for nsIRs LensIG, Lens, and H, their axes are selected to be parallel to each other.

In addition, each lens Lens11 (XLens, 0% Le
nslB are formed separately from each other so that these lenses LensIR% LensIG, Lens
Each transmission hole haa,) 13 of each end plate (32) and (41) of the third and fourth grids G3 and G4 constituting the IB
(is h3Bs h4Hs A peripheral side wall WS is provided around h4G and h4B.

For example, as shown in FIG.
) are thick, and each through hole h3HSh3G, h3
B and) k4Rs h40. By drilling h4B, the peripheral side wall Ws can be formed by the thickness of these end plates (32) and (41). In this case, if there is a problem in drilling the through holes in the thick end plates (32) and (41),
41) is composed of a laminate made of two or more thin sheets, each of which is laminated with a laser or the like, and a transparent hole that matches each other is drilled in each thin sheet in advance, and these are pasted together. Transmission holes h3R1h, G, h3B and h4R% each having a substantially thick circumferential side wall W+ formed around them when combined to form end plates (32) and (41), respectively
14G%) 14B is formed.

Alternatively, as shown in FIG.
h 3G% h 3B and h 4B% h 43%
While drilling h4B, a cylindrical peripheral side wall Ws can also be formed around it by drawing processing, so-called burring.

According to the above-described configuration, each front lens Lensut %
Since the optical axes of Lens1 (, LensIB) are formed parallel to each other, the electron beams BR and BB on both sides
For each lens LenslR and Len
The light is incident at a required angle with respect to the optical axis of stc. Each lens LensIR-, Lens13 is selected at a position that satisfies the Braunhoffer condition, that is, provides a condition where the coma aberration becomes zero. In this way, for the optical axis of each LenstR and Lenstc,
It is possible to avoid problems such as an increase in aberration due to oblique incidence of the beams BR and B11, and an increase in the spot size on the fluorescent surface of a color cathode ray tube, for example. FIG. 4 shows the measurement results of the spot size when the current of 1K was varied in a color cathode ray tube using the electron gun device τ of the present invention having the configuration shown in FIGS. 1 and 2. FIG. 5 shows the same spot size measurement results using the conventional electron gun device shown in FIG. 18, and as is clear from comparing FIG. 4 with FIG. As in the present invention, the front lens Le
Even when the optical axes of nStR1Lens'G and Lenses are selected to be parallel, there is no play of color because the Braunforfer condition is satisfied.

The example in FIG. 1 is a case in which the present invention is applied to an electron gun with a unipotential configuration corresponding to FIG. It can be applied to guns.

〔Effect of the invention〕

The present invention provides an electron gun in which aberrations are reduced by separating the main electron lens into a front lens and a rear lens, and making the aperture of the front lens smaller than that of the rear lens.
Since the optical axes of the front lens are made parallel without increasing aberrations, manufacturing becomes easier, the machining accuracy of each axis center position is improved, and it is possible to manufacture an electron gun with a stable designed feed rate. The industrial benefits are great.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an electrode arrangement of an example of an electron gun device according to the present invention, FIG. 2 is a cross-sectional view of a main part thereof, FIG. 3 is a cross-sectional view of a main part of another example of an electron gun device of the present invention, and FIG. 5 is a spot size measurement curve diagram of the device of the present invention, FIG. 5 is a spot size measurement curve diagram of the conventional device, FIG. 6 is an electrode arrangement diagram of the conventional device, and FIG.
8, 10, and 11 are configuration diagrams of the electronic lens, FIG. 9 is a curve diagram showing the relationship between the ratio of focal length and lens aperture, and the spherical aberration coefficient, and FIG. 12 is a diagram of the electron lens. 13 is a curve diagram showing the relationship between the aperture ratio of the front and rear lenses, the distance between them, and the object distance, and FIGS. 14 and 1
Figure 5 is a curve diagram showing spherical aberration, Figures 16 to 1q.
The figures are diagrams showing different electrode arrangement configurations of Yoto's electron gun devices. KR, KG and 8 are cathodes, GIR, GIG and 01B are first grids, G2-G6 are second to sixth grids, LensiH1LensiG and Lensle are front stage lenses, and Lens 2 is a rear stage lens.

Claims (1)

[Scope of Claims] (a) A plurality of cathodes are provided; (b) a main electron lens includes a front-stage electron lens action area individually provided on each path of the electron beam by each of the cathodes; and (c) an electron lens aperture of the electron lens system based on the front stage working area, which is separated from the electron lens working area and provided in common on the path of the plurality of beams; smaller than the electron lens aperture of the electron lens action area; (d) the central axes of the electron beam transmission holes of the electrodes constituting the preceding electron lens action area on the path of each electron beam are selected to be parallel to each other; (e) An electron gun device characterized in that each of the electron beams is selected so as to satisfy the Braunhofer condition with respect to each of the front-stage electron lens action areas.