JP2004146141A - Method and apparatus for assembling electron gun - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase accuracy in the assembly of an electron gun when assembling a cathode structure and a first control electrode. <P>SOLUTION: In an assembly method of the electron gun used for assembling the cathode structure 3 having a cathode 1 for discharging electrons and the first control electrode 6 for controlling electron discharge from the cathode 1, an image processing autofocus unit 12 is used to perform the focusing of an optical system to the electrode surface of the first control electrode 6 and that of the optical system to the electron discharge surface of the cathode 1 when the distance between the first control electrode 6 and the cathode 1 is set by allowing the first control electrode 6 to oppose the cathode 1, thus reducing variations in measurement. <P>COPYRIGHT: (C)2004,JPO

Description

【００４０】
上記表１はレーザーオートフォーカスユニットを用いた場合と画像処理オートフォーカスユニットを用いた場合の測定の繰り返し再現性を調べた実験結果を示すものである。ここでは陰極の電子放出面を測定対象部として、それぞれのオートフォーカスユニットで光学系の焦点合わせによる位置の測定を１０回ずつ行った場合の繰り返し再現性を、標準偏差（Ｓｄｔ）と最大ばらつき（Ｒ）で示している。この実験結果から、オートフォーカスユニットとして画像処理オートフォーカスを使用することにより、レーザーオートフォーカスユニットを使用する場合に比較して、測定の繰り返し再現性がほぼ１／３に軽減されることが確認された。
【００４１】
【表２】

【００４２】
また、実際の組み立て精度で比較してみた場合でも、上記表２に示すような実験結果が得られた。すなわち、組み立ての部品サンプル数をオートフォーカスユニットごとに２０個用意してそれぞれ部品の組み付けを行い、第１制御電極と陰極との距離Ｌａ，Ｌｂ（図３参照）とその差分について、目標値に対する平均値（Ａｖｅ）と標準偏差（Ｓｔｄ）を求めた。そうしたところ、オートフォーカスユニットとして画像処理オートフォーカスユニットを使用することにより、レーザーオートフォーカスユニットを使用する場合に比較して、目標値に対する寸法上のばらつきを１／３〜１／２程度に抑えられることが確認された。
【００４３】
なお、上記実施形態においては、組み立ての対象となる電子銃の構成として、一つの陰極に対して複数のビーム通過孔を有する第１制御電極を備えたマルチビーム方式の電子銃を例に挙げて説明したが、本発明はこれに限らず、一つの陰極に対して一つのビーム通過孔を有する第１制御電極を備えた電子銃を組み立てる場合にも適用可能である。
【００４４】
【発明の効果】
以上説明したように本発明によれば、第１制御電極の電極面に対する光学系の焦点合わせと陰極の電子放出面に対する光学系の焦点合わせを画像処理オートフォーカスユニットを用いて行うことにより、測定対象部となる電極面や電子放出面の表面状態に左右されることなく、測定対象部の位置を測定することができる。これにより、第１制御電極と陰極との距離を適切かつ高精度に設定することができる。
【図面の簡単な説明】
【図１】本発明の実施形態に係る電子銃の組み立て装置を示す概略図である。
【図２】組み立ての対象となる電子銃の構成例を示す図である。
【図３】陰極構体の回転位置を設定する前後の第１制御電極と陰極の配置状態を示す図である。
【図４】電子銃の部分的な構造例を示す図である。
【符号の説明】
１…陰極、３…陰極構体、６…第１制御電極、８Ａ，８Ｂ…ビーム通過孔、１２…画像処理オートフォーカスユニット、１５…第１の保持部、１６…第２の保持部、１９…演算処理装置[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method and an apparatus for assembling an electron gun, and more particularly, to a method and an apparatus used when assembling a cathode structure and a first control electrode.
[0002]
[Prior art]
The in-line type electron gun has a cathode (cathode) for emitting a plurality of electron beams arranged in-line in the horizontal direction, and a first control electrode (first electrode) having a beam passage hole at a position facing the cathode. Grid electrode).
[0003]
4A and 4B show an example of a partial structure of the electron gun, wherein FIG. 4A is a cross-sectional view and FIG. 4B is a plan view. As shown in the figure, the cathode 1 of the electron gun comprises a cathode structure 3 together with a cylindrical body (hereinafter referred to as a sleeve) 2 which holds the cathode 1 at its tip and in which a heating element (heater) for heating the cathode 1 is provided. Make up. The cathode structure 3 is held by a sleeve holder 4. The sleeve holder 4 is fixed to a holder fixing member (insulator) 5, and the cathode structure 3 is assembled to the first control electrode 6 via the holder fixing member 5. The first control electrode 6 is integrally fixed to the bead glass together with the second control electrode 7 adjacent thereto and other control electrodes (not shown).
[0004]
Generally, an electron gun of a color cathode ray tube has a cathode structure 3 corresponding to each of three primary colors of light such as red (R), green (G), and blue (B) for each color. Further, as shown in FIG. 4B, the first control electrode 6 of the electron gun is provided with one beam passage hole (hole through which an electron beam passes) 8 for one cathode 1. Is common. When assembling this type of electron gun, when assembling the cathode structure 3 to the first control electrode 6, a position for adjusting the distance between the first control electrode 6 and the cathode 1 to a preset reference distance (target value). Adjustment (collation) is performed.
[0005]
On the other hand, to form a high current density electron beam without exceeding the electron emission capability of a single cathode, and to have a plurality of beam passage holes for one cathode, to reduce the driving voltage of the cathode There is also known an electron gun employing a first control electrode to extract a plurality of electron beams from one cathode (hereinafter, a multi-beam method).
[0006]
In the multi-beam type electron gun, the distance between each beam passage hole of the first control electrode and the electron emission surface of the cathode opposed thereto has a large effect on cutoff characteristics, drive characteristics, electron beam crossover, and the like. . Therefore, when assembling the electron gun, it is necessary to set the distance between each beam passage hole of the first control electrode and the electron surface of the cathode as uniform as possible.
[0007]
In a general electron gun assembling process, in a state where a cathode holding member (sleeve holder, holder fixing member, etc.) for holding the cathode assembly is previously attached to the first control electrode, the assembled cathode assembly is attached to the cathode holding member. It is inserted and fixed by welding or the like.
[0008]
However, when assembling the cathode assembly, the cathode may be mounted in an inclined state due to a dimensional error of the cathode itself or a dimensional error of the sleeve. In addition, when inserting the cathode assembly into the cathode holding member, it is necessary to ensure a predetermined clearance between the two (the fitting portion), so that the cathode assembly may be inserted in an inclined state. Further, the electrode surface of the first control electrode may be formed to be inclined by press working.
[0009]
In such a case, the parallelism between the first control electrode and the cathode deteriorates when the first control electrode and the cathode assembly are assembled. As a result, the distance between one cathode and the corresponding beam passage hole of the first control electrode becomes non-uniform, and the operating characteristics (cutoff characteristics, drive characteristics, etc.) of the above-described electron gun deteriorate. .
[0010]
In order to assemble a cathode structure having a cathode and a first control electrode having a plurality of beam passage holes with respect to one cathode, the present applicant rotates the cathode structure around an axis to form each of the first control electrodes. The distance between the beam passage hole and the beam exit surface of the cathode is measured, and based on the measurement result, the rotational position of the cathode assembly is set under the condition that the difference in the distance between each beam passage hole and the beam exit surface is minimized. A technique has been proposed (see Patent Document 1).
[0011]
[Patent Document 1]
JP 2001-250476 A
[Problems to be solved by the invention]
However, in the technique described in Patent Literature 1, a laser autofocus unit using laser light is used as a focus unit for setting a distance between the first control electrode and the cathode. When focusing the optical system on the electron emission surface of the porous cathode, there is a problem that a measurement error is likely to occur due to the influence of minute irregularities on the cathode surface.
[0013]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and an object of the present invention is to increase the accuracy of assembling an electron gun when assembling a cathode structure and a first control electrode.
[0014]
[Means for Solving the Problems]
The present invention is a method for assembling an electron gun used when assembling a cathode assembly having a cathode that emits electrons and a first control electrode that controls electron emission from the cathode, wherein the first control electrode, the cathode, When the distance between the first control electrode and the cathode is set to face each other, the focusing of the optical system on the electrode surface of the first control electrode and the focusing of the optical system on the electron emission surface of the cathode are performed by image processing. This is performed using a focus unit.
[0015]
Further, the present invention is an assembling apparatus for an electron gun used when assembling a cathode structure having a cathode for emitting electrons and a first control electrode for controlling electron emission from the cathode, wherein the assembling apparatus holds the first control electrode. First holding means, a second holding means for holding the cathode assembly in a state where the cathode faces the first control electrode held by the first holding means, and a first holding means for holding the cathode structure. When the distance between the first control electrode and the cathode is set by facing the first control electrode and the cathode of the cathode assembly held by the second holding means, the optical system with respect to the electrode surface of the first control electrode And an image processing autofocus unit for focusing the optical system on the electron emission surface of the cathode.
[0016]
In the assembling method and the assembling apparatus for the electron gun, the focusing of the optical system on the electrode surface of the first control electrode and the focusing of the optical system on the electron emission surface of the cathode are performed by using an image processing autofocus unit. The position of the measurement target portion can be measured without being affected by the surface condition of the electrode surface or the electron emission surface serving as the measurement target portion.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the present embodiment, the same parts as those of the above-described related art will be denoted by the same reference numerals and described.
[0018]
FIG. 1 is a schematic view showing an electron gun assembling apparatus according to an embodiment of the present invention. In the illustrated electron gun assembling apparatus, the measuring unit 10 and the work holding unit 11 are arranged so as to face up and down. The measurement unit 10 includes an image processing autofocus unit (hereinafter abbreviated as image processing AFU) 12, a displacement measuring device 13, and a motor 14 for lifting. The work holding unit 11 includes a first holding unit 15, a second holding unit 16, a rotation motor 17, and a lifting / lowering motor 18.
[0019]
The arithmetic processing device 19 controls the operation of the entire device according to a preset control program. The arithmetic processing unit 19 is electrically connected to the image processing AFU 12, the displacement measuring device 13, the lifting / lowering motor 14, the rotation motor 17, and the lifting / lowering motor 18, respectively.
[0020]
The image processing AFU 12 includes, for example, an illumination lamp (light source) for irradiating light to the measurement target portion, an image pickup device such as a CCD sensor that receives reflected light from the measurement target portion and generates an image signal, and a measurement target portion. It is configured using a lens system that forms an image of the reflected light on the light receiving surface of the image sensor, optical components such as a half mirror and an optical filter, and an image processing unit that processes an image signal generated by the image sensor. The image processing AFU 12 is supported by an XY stage (not shown) so as to be movable in two horizontal axis directions. The image processing AFU 12 is supported by a support mechanism (not shown) so as to be movable up and down (movable up and down). When the lift motor 14 is driven to rotate, the image processing AFU 12 moves up and down accordingly.
[0021]
The image processing AFU 12 irradiates light (for example, visible light) to a measurement target portion (in the present embodiment, the first control electrode 6 and the cathode 1), and receives reflected light from the measurement target portion by an imaging element to form an image. A signal is generated, and the focus of the optical system is adjusted to the measurement target unit by the autofocus processing of the image processing unit using the image signal. In the autofocusing process of the image processing unit, the image processing AFU 12 is raised or lowered within a predetermined range including the focus position by driving the lifting / lowering motor 14, and the image signal of the measurement target unit during the lifting / lowering operation is changed. A point where the high frequency component of the image signal generated by the image sensor is the largest is detected as a focus point. Then, the lifting / lowering motor 14 is driven so as to coincide with the focus point, and the image processing AFU 12 itself is raised / lowered.
[0022]
The displacement measuring device 13 detects the movement amount (displacement amount) of the image processing AFU 12 in the vertical direction with high accuracy (for example, on the order of submicron) in order to measure the position of the measurement target unit by the image processing AFU 12. . As the displacement measuring device 13, for example, a magnetic displacement measuring scale can be used.
[0023]
The first holding unit 15 holds the first control electrode 6. The first holding unit 15 holds the first control electrode 6 in a horizontal state together with the sleeve holder 4 and the holder fixing member 5 by, for example, an openable / closable clamper. The sleeve holder 4 and the holder fixing member 5 are previously assembled integrally with the first control electrode 6, and the assembly component obtained by this is held by the first holding unit 15.
[0024]
The second holding unit 16 holds the cathode structure 3 including the cathode 1 and the sleeve 2. The second holding portion 16 has a rod-shaped workpiece receiving member 20 that receives the sleeve 2 of the cathode assembly 3 at the tip end (upper end). In addition, the second holding unit 16 is supported by a support mechanism (not shown) so as to be movable in the vertical direction.
[0025]
The sectional shape of the work receiving member 20 is circular in accordance with the sectional shape of the sleeve 2. The outer diameter of the work receiving member 20 is set slightly smaller than the inner diameter of the rear end of the sleeve 2 (the side opposite to the portion where the cathode 1 is attached), so that the front end of the work receiving member 20 is It is configured to be removable.
[0026]
While the first control electrode 6 is held by the first holding unit 15 and the cathode assembly 3 is held by the second holding unit 16, the first control electrode 6 and the cathode 1 are positioned vertically. It will be in the state of facing.
[0027]
The rotation motor 17 rotates the work receiving member 20 in the θ direction via a power conversion mechanism (for example, a belt transmission, a gear transmission mechanism, etc.) not shown. The elevating motor 18 varies (adjusts) the distance between the first control electrode 6 and the cathode 1 in the vertical direction by moving the second holding unit 16 up and down integrally with the rotating motor 17.
[0028]
Subsequently, a method of assembling the electron gun according to the embodiment of the present invention will be described together with an operation procedure of the assembling apparatus based on a control command from the arithmetic processing unit 19. The configuration of the electron gun to be assembled is, for example, as shown in the plan view of FIG. 2A and the cross-sectional view taken along the line MM of FIG. The case where the first control electrode 6 having the holes 8A and 8B is employed will be described as an example. The first control electrode 6 is formed in a state where the electrode surface near the beam passage holes 8A and 8B is recessed into a circular stepped shape in plan view by press working.
[0029]
First, an assembly component (work) including the sleeve holder 4, the holder fixing member 5, and the first control electrode 6 is held by the first holding unit 15, and the rear end of the sleeve 2 is attached to the front end of the work receiving base 20. The cathode structure 3 (work) is inserted and held by the second holding unit 16. At this time, the cathode structure 3 set on the work receiving table 20 is retracted below the position where the first holding unit 15 holds the assembly component.
[0030]
Next, the second holding unit 16 is raised by driving the elevating motor 18 based on a control command from the arithmetic processing unit 19, whereby the cathode assembly 3 is inserted into the sleeve holder 4. At this time, the position (height) of the cathode 1 in the vertical direction is adjusted such that the distance between the cathode 1 and the first control electrode 6 is larger than a preset reference distance (target value). .
[0031]
Next, in the vicinity of the two beam passage holes 8A and 8B provided in the first control electrode 6, light from the image processing AFU 12 is irradiated on the electrode surface of the first control electrode 6, and the reflected light therefrom is used. By the above-described auto-focusing process, the optical system focuses on the electrode surface of the first control electrode 6, and in this state (focused state), the coordinate values of the XY stage and the measured values of the displacement measuring device 13 are read. Thereby, three-dimensional coordinate data (X, Y, Z coordinate data) in which the coordinate data of the measurement target portion in the horizontal direction and the coordinate data of the measurement target portion in the vertical direction are associated with each other is obtained. At this time, in the vicinity of the two beam passage holes 8A and 8B, a plurality of locations (four locations P1 to P4 in the example) on the electrode surface of the first control electrode 6 are set as measurement target portions. Acquire three-dimensional coordinate data.
[0032]
Subsequently, the electron emission surface (tip surface) of the cathode 1 is irradiated with light from the image processing AFU 12 through the respective beam passage holes 8A and 8B of the first control electrode 6, and the reflected light from the electron emission surface is used. By performing the above-described autofocus processing, the focus of the optical system is focused on the electron emission surface of the cathode 1, and in this state (focused state), the coordinate values of the XY stage and the measurement values of the displacement measuring device 13 are read, thereby obtaining the cathode 1. , Three-dimensional coordinate data are obtained at two points P5 and P6 on the electron emission surface.
[0033]
Next, by driving the rotation motor 17 based on the control command from the arithmetic processing unit 19, the work receiving base 20 rotates in one of the θ directions, and when the rotation angle reaches 90 degrees, the work receiving twentieth stops. I do. At this time, the rotation of the work receiving base 20 causes the cathode structure 3 to rotate about the axis integrally therewith. When the cathode assembly 3 is rotated in this way, the electron emission surface (tip surface) of the cathode 1 is again irradiated with light from the image processing AFU 12 through the respective beam passage holes 8A and 8B of the first control electrode 6, The autofocus process using the reflected light from the electron emission surface focuses the optical system on the electron emission surface of the cathode 1 and, in this state (focused state), the coordinate values of the XY stage and the displacement measuring device 13 , Three-dimensional coordinate data is obtained at each of two points P5 and P6 on the electron emission surface of the cathode 1. In this case, the position of the measurement target portion on the electron emission surface differs by 90 degrees before and after rotating the cathode structure 3.
[0034]
Subsequently, the coordinate data of four locations read by focusing the optical system on the electrode surface of the first control electrode 6 and focusing the electron system on the electron emission surface of the cathode 1 before rotating the cathode assembly 3. For example, using the coordinate data of two places read by reading the coordinate system and the coordinate data of two places read by focusing the optical system on the electron emission surface of the cathode 1 after rotating the cathode assembly 3 by 90 degrees, for example, By performing arithmetic processing in the arithmetic processing device 19 by the square method, a rotation angle at which the electrode surface of the first control electrode 6 and the electron emission surface of the cathode 1 opposed thereto are substantially parallel is calculated, and the calculated rotation is calculated. The rotation position of the cathode assembly 3 is set by driving the rotation motor 17 according to the angle.
[0035]
Thereby, even if the electrode surface of the first control electrode 6 is greatly inclined with respect to the electron emission surface of the cathode 1 as shown in FIG. By rotating the structure 3, the electrode surface of the first control electrode 6 and the electron emission surface of the cathode 1 can be arranged in parallel as shown in FIG. As a result, the rotational position of the cathode assembly 3 can be set under the condition that the difference between the distances La and Lb between the electrode surface near the beam passage hole of the first control electrode 6 and the electron emission surface of the cathode 1 is minimized. .
[0036]
Next, by driving the elevating motor 18, the distances La and Lb between the electrode surfaces near the beam passage holes 8A and 8B of the first control electrode 6 and the electron emission surface of the cathode 1 match the aforementioned reference distance. The position (height) of the cathode 1 is adjusted as described above. In this case, since the distance between the cathode 1 and the first control electrode 6 is set to be larger than the reference distance in advance, the position is adjusted in the direction in which the cathode assembly 3 approaches the first control electrode 6 here.
[0037]
Thereafter, the sleeve 2 is fixed to the sleeve holder 4 by a fixing means such as laser welding while the cathode structure 3 is held by the work holding member 20. Thereby, the assembly component including the first control electrode 6 and the cathode assembly 3 are assembled, and the positional relationship between the first control electrode 6 and the cathode 1 is fixed. The above assembling work is performed for each cathode 1 corresponding to each of R, G, and B colors.
[0038]
As described above, in the present embodiment, when the distance between the first control electrode 6 and the cathode 1 is set, the focusing of the optical system is performed using the image processing AFU 12, so that the electrode surface serving as the measurement target portion and the electron emission The position of the measurement target portion can be accurately measured without being affected by the surface condition of the surface. Thereby, the assembling accuracy when assembling the cathode structure 3 to the first control electrode 6 can be improved. As a result, the operating characteristics of the electron gun can be stabilized. In addition, the use of the image processing AFU 12 makes it possible to easily measure the position by focusing on one point, multiple points, or the entire area.
[0039]
[Table 1]

[0040]
Table 1 above shows the experimental results of examining the reproducibility of measurement when the laser autofocus unit was used and when the image processing autofocus unit was used. Here, with the electron emission surface of the cathode as a measurement target portion, the repeatability when the position of each optical focusing unit is measured 10 times by focusing on the optical system is determined by the standard deviation (Sdt) and the maximum variation (Sdt). R). From these experimental results, it was confirmed that the use of the image processing autofocus as the autofocus unit reduced the reproducibility of measurement to almost one-third as compared with the case of using the laser autofocus unit. Was.
[0041]
[Table 2]

[0042]
In addition, even when the actual assembly accuracy was compared, experimental results as shown in Table 2 above were obtained. That is, the number of component samples for assembly is prepared for each autofocus unit, and the components are assembled respectively. The distances La and Lb between the first control electrode and the cathode (see FIG. 3) and the difference between the first control electrode and the cathode are compared with the target value. The average value (Ave) and standard deviation (Std) were determined. In such a case, by using the image processing autofocus unit as the autofocus unit, the dimensional variation with respect to the target value can be suppressed to about 1/3 to 1/2 as compared with the case of using the laser autofocus unit. It was confirmed that.
[0043]
In the above-described embodiment, as a configuration of an electron gun to be assembled, a multi-beam type electron gun including a first control electrode having a plurality of beam passage holes for one cathode is exemplified. Although the present invention has been described, the present invention is not limited to this, and is also applicable to a case where an electron gun having a first control electrode having one beam passage hole for one cathode is assembled.
[0044]
【The invention's effect】
As described above, according to the present invention, measurement is performed by performing focusing of the optical system on the electrode surface of the first control electrode and focusing of the optical system on the electron emission surface of the cathode using an image processing autofocus unit. The position of the measurement target portion can be measured without being affected by the surface condition of the electrode surface or the electron emission surface serving as the target portion. Thereby, the distance between the first control electrode and the cathode can be set appropriately and with high accuracy.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an electron gun assembling apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram showing a configuration example of an electron gun to be assembled.
FIG. 3 is a diagram showing an arrangement state of a first control electrode and a cathode before and after setting a rotational position of a cathode assembly.
FIG. 4 is a diagram showing an example of a partial structure of an electron gun.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Cathode, 3 ... Cathode structure, 6 ... 1st control electrode, 8A, 8B ... Beam passage hole, 12 ... Image processing autofocus unit, 15 ... 1st holding | maintenance part, 16 ... 2nd holding | maintenance part, 19 ... Arithmetic processing unit

Claims (4)

A method for assembling an electron gun used when assembling a cathode assembly having a cathode that emits electrons and a first control electrode that controls electron emission from the cathode,
When the distance between the first control electrode and the cathode is set with the first control electrode and the cathode facing each other, focusing of the optical system on the electrode surface of the first control electrode and electron emission of the cathode are performed. A method for assembling an electron gun, wherein focusing of an optical system on a surface is performed using an image processing autofocus unit. The first control electrode has a plurality of beam passage holes for one cathode ray tube,
By focusing the optical system on the electron emission surface of the cathode using the image processing autofocus unit a plurality of times by rotating the cathode assembly around an axis, the electrode surface of the first control electrode and the 2. The electron gun according to claim 1, wherein a rotation angle of the cathode assembly at which an electron emission surface of the opposed cathode is substantially parallel is calculated, and a rotation position of the cathode assembly is set according to the rotation angle. How to assemble. A cathode assembly having a cathode that emits electrons, and an assembling apparatus for an electron gun used when assembling a first control electrode that controls electron emission from the cathode,
First holding means for holding the first control electrode;
Second holding means for holding the cathode assembly in a state where the cathode faces the first control electrode held by the first holding means;
The distance between the first control electrode and the cathode is set by facing the first control electrode held by the first holding unit and the cathode of the cathode assembly held by the second holding unit. And an image processing autofocus unit for focusing the optical system on the electrode surface of the first control electrode and focusing the optical system on the electron emission surface of the cathode. apparatus. The first control electrode has a plurality of beam passage holes for one cathode ray tube,
Rotating means for rotating the cathode assembly held by the second holding means around an axis;
When rotating the cathode assembly around an axis by the rotating means and performing the focusing of the optical system with respect to the electron emission surface of the cathode a plurality of times by the image processing autofocus unit, the electrode surface of the first control electrode and Setting means for calculating a rotation angle of the cathode assembly in which an electron emission surface of the cathode opposed thereto is substantially parallel, and driving the rotation means in accordance with the rotation angle to set a rotation position of the cathode assembly; The electron gun assembling apparatus according to claim 3, comprising:

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