JPH04106844A - Electron gun for cathode-ray tube - Google Patents

Abstract

PURPOSE:To carry out assembly easily and precisely by attaching a pair of supporting plates to cover the maximum diameter part of a flat cylinder part of a first electrode to a second electrode and installing supporting pieces in both sides so as to pinch a supporting piece of the first electrode in the supporting plates. CONSTITUTION:A fifth grid G5 which is a first electrode is composed of a large diameter cylindrical part 31 and an oblong flat cylindrical part 32 whose maximum diameter is smaller than the diameter of the large diameter cylindrical part and a supporting piece 36 is installed in the center part of the oblong side plane of the flat cylindrical part 32 and meanwhile a pair of supporting plates 34 to cover the maximum diameter part of the flat cylindrical part 32 of the fifth grid G5 are installed in a cathode K side of a cylinder part 33. Supporting pieces 37 are so installed in the pair of the supporting plates 34 as to pinch the supporting piece 36 of the flat cylindrical part 32 from both sides. Consequently, in spite of an electron gun with a special structure having two large diameter cylindrical parts 31, 33, it is assembled easily and highly precisely.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an electron gun for a cathode ray tube, and more particularly to an electron gun for a cathode ray tube having a large diameter electron lens that can be assembled with high precision.

(Prior Art) Generally, a cathode ray tube has an envelope (1) as shown in FIG.
A phosphor screen (3) is placed on the inner surface of the face plate (2).
) is formed and the electron beam (6) emitted from the electron gun (5) disposed inside the neck (4) of the envelope (1) is directed to a deflection yoke attached to the outside of the envelope (1). The phosphor screen (3) is deflected by the magnetic field generated by (7) to horizontally and vertically scan the phosphor screen (3), thereby displaying an image.

Especially for color picture tubes, the phosphor screen (3)
A shadow mask (8) with a large number of electron beam passage holes formed inside the mask is mounted facing the electron gun (8).
5) is used as an electron gun that emits three electron beams, the electron beam (6) emitted from this electron gun (5) is sorted by the electron beam passing hole of the shadow mask (8), and then passed through the phosphor screen (3). By landing the three color phosphor layers constituting the phosphor layer, the structure is formed to display an image.

The electron gun mentioned above has various structures, but generally consists of a cathode and a plurality of electrodes that control electron emission from the cathode and focus the emitted electrons to form an electron beam. and a main electron lens section consisting of a plurality of electrodes that focus the electron beam emitted from the electron beam forming section onto a phosphor screen (3).

By the way, in order to improve the image drawn on the phosphor screen, it is necessary to make the beam spot of the electron beam on the phosphor screen smaller. To this end, it is necessary to improve the lens performance of the electron lens, especially the main electron lens section. As a means of improving the lens performance of the main electron lens section, it is known that it is better to increase the lens diameter to form a large-diameter electron lens.

As an electron gun with a large diameter electron lens,
Publication No. 7-18885 includes figures 5 (a) and (b).
As shown in , the aperture of the cathode side electrode that forms the main electron lens section is made large so that it is as close to the inner diameter of the neck as possible.
A structure in which the diameter of the electrode on the phosphor screen side is smaller than that is shown. That is, in the main electron lens section shown in FIG. 5(a), the large diameter cathode side electrode (10) and the small diameter phosphor screen side electrode (11) are connected via an insulating support member made of ceramic (12). It is fixed. Regarding the main electron lens shown in (b), the large diameter cathode side electrode (10) and the small diameter phosphor screen side electrode (11) are fixed by an insulating support member made of bead glass (13). ing.

However, if the main electron lens section is configured as described above, in the case of a device in which both electrodes (10) and (11) are fixed via a ceramic (12), ■ In the case of a color picture tube to which a high voltage is applied. , the withstand voltage becomes insufficient, causing dielectric breakdown.

■ Ceramics that are difficult to process must be processed with high precision, which poses an economical problem.

■ Stoppers <14a) and (14b) must be used to fix the electrodes (10) and (11) to the ceramic (12), making assembly difficult.

■Occluded gas from the ceramic (12) is released.

There are other problems.

In addition, both electrodes (11)) and (11) were connected to bead glass (1
3) is difficult to assemble by heating and melting the bead glass from one side and fusing it to the support piece of the electrode, as in the assembly of a normal electron gun. Also, there is no other suitable assembly method.

Regarding such an electron gun, Japanese Patent Publication No. 58-31698 describes a second anode (fifth grid) (1
The cathode (K) side end of B) is made small in diameter, and the support piece (17) provided at this small diameter part is used as an insulating support member (18).
On the other hand, the first anode (fourth grid (19)) is divided into two parts, and the small diameter part of the second anode (16) is attached to the cathode (K) side of the large diameter part (20). A structure is shown in which a small-diameter neck portion (21) is formed that passes through the electron gun without contacting it, and the neck portion (21) is connected to the cathode side portion (22) when the electron gun is assembled.

However, this structure does not sufficiently solve the problem of reduced accuracy and difficulty in assembly due to the connection of the two divided parts.

As an improved structure of this electron gun, as shown in FIG. A part of the anode (3rd grid) (19) is recessed inward to form a recessed part (24), and when assembling the electron gun, the first anode (third grid) (19) is inserted into the second anode (19) as shown in FIG. 16), the support piece (25) of the first anode (19) and the recessed part (24) of the second anode (16) are avoided, and the Return the angle θ to the original position, position the support piece (25) of the first anode (19) and the support piece (17) of the second anode (16) on the same plane, and fuse them to the insulating support member (18). The one with a structure that is fixed by hand is shown. 9(a) and (b) respectively show the second anode (
16) are the structures of different invaginations (25).

However, in any case, in the structure of this example, during assembly, it is necessary to rotate the first anode (19) and the second anode (16) by an angle θ relative to each other, insert them, and return them to the light after insertion. Therefore, assembly is still complicated and mass productivity is lacking. In particular, the structure shown in FIG. 9(a) has low mechanical strength and has problems in practical use.

Further, in the structure as shown in FIG. 9(b), similarly to the electron gun shown in FIG. 7, the decrease in accuracy and the difficulty in assembly due to the connection of the two divided parts cannot be sufficiently resolved.

Furthermore, such a large diameter electrode (first anode (19)) and another large diameter electrode surrounding this electrode (second anode (19))
When forming a large-diameter electron lens with lEi)), both electrodes are quite long, so these electrodes must be supported and fixed extremely firmly. However, in the above electron gun, the support piece (25) of the first anode (19)
) and the support piece (17) of the second anode (1B) are located on the same plane and apart from each other in the axial direction of the electron gun, and are supported and fixed by the insulating support member (18). In order to strengthen the support of the anode (1B), the end of the second anode (16) on the cathode (K) side inevitably becomes longer. However, in this way, the cathode (K) of the second anode (16)
) side end becomes longer, the support piece (25) of the first anode (19) must be moved to the cathode (K) side due to voltage resistance. The withstand voltage with the second grid (2B) becomes a problem, and this
The length of the anode (19) from the support piece (25) to the phosphor screen side becomes long, making it impossible to firmly support and fix it.

In particular, if the support and fixation of the first anode (19) is not strong and the part on the phosphor screen side moves, not only will the axis of the electron lens move, but also the part on the phosphor screen side of the first anode (19) will move. Large diameter part (27) and second anode (1B)
The small gap between the large diameter portion (28) of the first anode (1
9) and the second anode (16), which is a fatal defect.

(Problem to be Solved by the Invention) As described above, in order to improve the performance of the electron lens of an electron gun, the main electron lens portion thereof is a large-diameter electron lens, and this large-diameter electron lens is replaced by a large-diameter electron lens. There is one formed by one electrode and another large-diameter second electrode that surrounds the large-diameter portion of the first electrode. However, this conventional large-diameter electron lens has problems such as being difficult or complicated to assemble, and difficult to assemble with high precision. Furthermore, it is difficult to firmly support and fix both electrodes, leading to problems such as withstand voltage and short circuits due to contact between the electrodes.

This invention was made to solve the above problems, and is formed by a first electrode having a large diameter and a second electrode having a large diameter surrounding the large diameter portion of the first electrode. In an electron gun having a large diameter electron lens, it is possible to construct a highly practical electron gun that is easy to assemble, has high mass productivity, has strong electrode support, and can be assembled with high precision. purpose.

[Structure of the Invention] (Means for Solving the Problems) An electron beam forming unit comprising a cathode and a plurality of electrodes that control electron emission from the cathode and focus the emitted electrons to form an electron beam; It has a main electron lens section consisting of a plurality of electrodes that focuses the electron beam emitted from the electron beam forming section onto a phosphor screen,
In a cathode ray tube electron gun in which a cathode and a plurality of electrodes forming an electron beam forming section and a main electron lens section are fixed together by an insulating support member via support pieces provided on the cathode and the plurality of electrodes, The main electron lens part has a large-diameter cylindrical part facing the phosphor screen, and a flat cylindrical part having a maximum diameter smaller than that of the large-diameter cylindrical part is integrally formed on the cathode side of the large-diameter cylindrical part. a second electrode having a large-diameter cylindrical portion surrounding the large-diameter cylindrical portion of the first electrode; On the other hand, a pair of support plates that cover the maximum diameter part of the flat cylindrical portion of the first electrode are attached to the second electrode, and the support pieces of the first electrode are attached to the pair of support plates. Support pieces fixed to the insulating support member were provided so as to be sandwiched from both sides.

(Function) As described above, the first electrode is composed of a large-diameter cylindrical portion and a flat cylindrical portion whose maximum diameter is smaller than that of the large-diameter cylindrical portion, and a support piece is provided on this flat cylindrical portion. , the first electrode to the second electrode
If a pair of support plates is attached to cover the maximum diameter part of the flat cylindrical part of the electrode, and support pieces are provided on the pair of support plates so as to sandwich the support piece of the first electrode from both sides, these first and second electrodes can be insulated. A support piece for fixing to the support member can be provided near the large-diameter cylindrical portion of each electrode, and the first and second electrodes can be firmly supported and fixed to the insulating support member.

Moreover, if a pair of support plates is attached to the second electrode that covers the maximum diameter part of the flat cylindrical part of the first electrode, and support pieces are provided on the pair of support plates so as to sandwich the support pieces of the first electrode from both sides, it is possible to As shown in the figure, the first electrode can be easily inserted inside the second electrode without rotating, and it can be supported and fixed to an insulating support member in the same way as a normal electron gun, making assembly easy.

Furthermore, since the large-diameter cylindrical part of the first electrode and the large-diameter cylindrical part of the second electrode surrounding it have a simple integral structure, high-precision assembly is possible, and a high-precision electron lens can be assembled. can be formed.

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

FIG. 1 shows an electron gun for a cathode ray tube, which is one embodiment of the present invention.

This electron gun includes a cathode (K), a heater for heating the cathode (K), and first to fourth guns (Gl) to (G4) arranged sequentially from the cathode (K) toward the phosphor screen. It consists of a fifth electrode (Gl) (first electrode) and a sixth electrode (second electrode) (G6).

The first and second grids (Gl) and (G2) are composed of relatively thin plate electrodes. Third grid (G
3) consists of a cylindrical electrode made up of two relatively shallow cup electrodes butted against each other. The fourth electrode (G4) consists of a relatively thick plate-shaped electrode. The fifth grid (G5) consists of one comparatively thick plate-shaped electrode plate 30) and four sets of cylindrical electrodes made up of two cup electrodes. The electrode on the phosphor screen side has a large diameter cylindrical part (31) and a maximum diameter smaller than the large diameter cylindrical part (31) attached to the cathode (K) side of this cylindrical part (31). It is composed of a horizontally long flat cylinder part (32).

Further, the sixth grid (G6) is the fifth grid (G5).
) with a large diameter cylindrical portion (31) surrounding the large diameter cylindrical portion (31) of the
3), and a pair of support plates (34) are attached to the cathode (K) side of this cylindrical part (33) to cover the maximum diameter part of the flat cylindrical part (32) of the fifth grid (G5). It is formed.

The cathode (K), the heater, and the first to sixth grids (G1) to (G6) are each supported and fixed by a pair of insulating support members (35) via support pieces. Regarding the support and fixation by the pair of insulating support members (35), the electron gun of this example is particularly suitable for the fifth grid (G5).
), a support piece (36) is attached to the center of the long side of the horizontally long flat cylinder part (31), while for the sixth grid (G6), a support piece (36) is attached to the electrode on the phosphor screen side. (G5) Cut and raise the side edges of the pair of support plates (33) that cover the maximum diameter part of the flat cylinder part (31), and raise the support piece (36) at the center of the long side of the flat cylinder part (31). Support pieces (37) are formed to sandwich the electron gun from both sides in the horizontal direction, and the support pieces (37) are slightly offset from the support pieces (36) in the axial direction of the electron gun.

The voltage applied to each electrode of this electron gun is applied to the cathode (
K) is set to O~200V, a video signal is added to it, the first grid (G1) is set to ground potential, and the second grid (G1) is set to the ground potential.
2) +: 500V to 1 kV, 3rd grid (G
3) 5-10kV, 4th grid (G4) 0-1k
V, 5th grid (G5) 1: 5-10 kV, 6th grid (GO) 1 m A high voltage of 20-40 kV is applied.

By applying the above voltage, the cathode (K) and the first to third grids (G1) to (G3) are connected to the cathode (K).
The third and fourth grids (G3) are formed with an electron beam forming section that controls electron emission from the grid (G3) and focuses the emitted electrons to form an electron beam.

(G4) and the fourth grid (G5) of the fifth grid (G5)
The electrode (30) on the G4) side forms a unipotential electron lens that weakly focuses the electron beam emitted from the electron beam forming section, and a large diameter cylindrical lens on the phosphor screen side of the fifth grid (G5) (31) and a large diameter cylindrical part (33) of the sixth grid (G6) surrounding this cylindrical part (31), a large diameter cylindrical part (33) that strongly focuses the electron beam focused by the unipotential electron lens is formed. An electronic lens is formed. As a result, the beam spot on the phosphor screen can be significantly reduced by focusing the large-diameter electron lens.

Incidentally, the above electron gun is assembled from the opening side of the tip of the large diameter cylindrical part (33) of the sixth grid (G6) shown in FIG. 2(a) to the fifth grid (G6) shown in FIG. 2(b). G5), and insert the fifth and sixth grids (G5) and (G8)
A combination of the heater and the cathode (K), one plate electrode (30) of the first to fourth grids (G1) to (G4) and the fifth grid (G5), and four sets of After positioning and arranging the cathode (K) side portion consisting of a cylindrical electrode in a predetermined relationship in an electron gun assembly jig, the heater, the support piece of the cathode (K), and the support piece of each grid are heated and melted. It is assembled by pressing and fusing a pair of insulating support members.

That is, as mentioned above, the fifth grid (G5) is composed of a large diameter cylindrical part (31) and a horizontally long flat cylindrical part (32) whose maximum diameter is smaller than this large diameter cylindrical part (31). A support piece (36) is provided at the center of the long side of the flat cylindrical portion (32), while the sixth grid (G6) is attached to the large diameter cylindrical portion (33).
) is attached with a pair of support plates (34) covering the maximum diameter part of the flat cylinder part (32) of the fifth grid (G5), and the fifth grid (
When supporting pieces (37) are provided to sandwich the supporting pieces (36) of the flat cylindrical part (32) of G5) from both sides, an electron gun with a special structure having two large-diameter cylindrical parts (31) and (33) is created. However, it can be easily assembled like a normal electron gun.

Moreover, as mentioned above, the fifth and sixth grids (G5)
, (G6), it is possible to assemble this type of electron gun with high precision, which has been difficult to assemble with high precision in the past. That is, in general, in order to firmly support and fix an electrode having a large-diameter cylindrical portion, it is preferable to place the support piece for fixing the electrode to the insulating support member as close to the large-diameter cylindrical portion as possible. For this purpose, the special public service of 1983 shown in Fig. 5(b)
Although there is a support means disclosed in Japanese Patent No. 18865, it is difficult to fuse the support piece to the insulating support member with this support means, making it impractical.

Further, the ceramic method shown in FIG. 5(a) is not practical in terms of cost and accuracy. Furthermore, in the support means of Japanese Patent Publication No. 2-18537 shown in FIG.
Since the anode is provided with a support piece near its large diameter portion, it is firmly supported and fixed, but the first anode, which is located inside the second anode, has a support piece that is far away from its large diameter portion. Because of this, it cannot be firmly supported and fixed. In order to firmly support and fix the first anode, it is possible to make the support piece larger, but increasing the size of the support piece has limitations in terms of withstand voltage characteristics and electron gun design, and is not practical. It is difficult to use it as an electron gun.

On the other hand, the electron gun in this example has the fifth and sixth grids (
G5) and (GO> are both large diameter cylindrical portions (31).

Since the support pieces (38) and (37) are provided near (33), both grids (G5) and (G6) can be firmly supported and fixed. That is, the support piece (
3B), a pair of supports covering the maximum diameter part of the flat cylinder part (32) of the fifth grid (G5) is placed on the cathode (K) side of the large diameter cylinder part (33) of the sixth grid (G6). Board (34
) is attached, and support pieces (37) are provided on the pair of support plates (34) so as to sandwich the support piece (3B) of the fifth grid (G5) from both sides in the horizontal direction. 6
Grid (G5) and (GB) both have a large diameter cylindrical part (
Support pieces (3B) and (37) are placed near 31) and (33).
), thereby allowing both grids (G5)
, (G6) can be firmly supported and fixed, and the electron gun can be assembled with high precision.

In this case, the distance between the support piece (36) of the fifth grid (G5) and the support piece (37) of the sixth grid (G6) is
, the sixth grid (G5), (GO) with a size that compensates for the withstand voltage characteristics, that is, the support pieces (3B), (3
7) The size is set so that no discharge occurs between the two. In addition,
The spacing between both support pieces (3B) and (37) is such that the width of the insulating support member (35) is increased and the width of the fifth grid (G
Slightly shift the support piece (37) of the sixth grid (G6) in the axial direction of the electron gun with respect to the support piece (36) of 5) to maintain a sufficient distance as in the axial direction arrangement of a normal electron gun. By doing so, it is possible to provide sufficient margin in the withstand voltage characteristics between both grids (G5) and (G6). In addition, the support piece (36) of the fifth grid (G5) and the sixth grid (G6)
It is desirable that the support pieces (37) are positioned substantially on the same plane perpendicular to the tube axis.

Furthermore, the electron gun of this example has an integral structure in which the large diameter cylindrical parts (31) and (33) of the fifth and sixth grids (05) and (G8) forming the large diameter electron lens are not divided. This has the advantage that high-precision electronic lenses can be formed.

[Effect of the invention] The main electron lens unit that focuses the electron beam emitted from the electron beam forming unit onto the phosphor screen has a large diameter cylindrical part on the phosphor screen side, and a cathode side of the second large diameter cylindrical part. A first electrode integrally formed with a flat cylindrical part having a maximum diameter smaller than the large diameter cylindrical part, and a second electrode having a large diameter cylindrical part surrounding the large diameter cylindrical part of the first electrode. The first electrode is provided with a supporting piece fixed to an insulating support member on the long side of the flat cylindrical portion, and the second electrode is provided with a pair of supporting pieces that cover the maximum diameter portion of the flat cylindrical portion of the first electrode. If a support plate is attached to the pair of support plates, and support pieces fixed to the insulating support member are provided on the pair of support plates so as to sandwich the support piece of the first electrode from both sides, then the support pieces of the first and second electrodes can be fixed to each other. Since it can be provided near the large diameter cylindrical portion, it can be firmly supported and fixed to the insulating support member. In addition, since the supporting pieces of the second electrode are provided so as to sandwich the supporting pieces of the first electrode from both sides, mass production can be done easily and in the same way as a normal electron gun, without requiring the complicated and difficult assembly method of the conventional electron gun. It can be assembled with high precision using a variety of methods. Furthermore, since the first and second electrodes can be firmly supported and fixed, the large-diameter electron lens can be formed with high accuracy and its lens performance can be improved, making it possible to provide a high-performance and practical electron gun. Furthermore, since the distance between the support piece of the first electrode and the support piece of the second electrode can be made sufficiently large as in the axial direction arrangement of a normal electron gun, withstand voltage can also be ensured.

[Brief explanation of the drawing]

Figures 1 to 3 are detailed explanatory diagrams of this invention.
Figure axes) to (C) are respectively a front view showing the configuration of an electron gun for a cathode ray tube, which is an example thereof, a sectional view taken along the line B-B, and a side view showing the main parts thereof. , 5th
The diagrams are for explaining the combination of the grid and the sixth grid, in which Figure 2 is a perspective view of the sixth grid, Figure 3 is a perspective view of the fifth grid, and Figures 4 to 9 are diagrams of conventional electronic grids. These are diagrams for explaining the gun. Figure 4 is a diagram showing the configuration of a color picture tube, and Figures 5 (a) and (b) are diagrams each showing the assembly structure of electrodes forming a conventional large-diameter electron lens. , FIG. 6 is a diagram showing different assembly structures of electrodes forming a large-diameter electron lens, and FIGS. 7(a) and (b) are partial cross-sections of further different assembly structures of electrodes forming a large-diameter electron lens, respectively. 8 is a diagram for explaining how to assemble the main parts, and FIGS. 9(a) and 9(b) are respectively sectional views of the first and second anode parts.
FIG. 3 is a diagram showing different structures of the anode. 31... Large diameter cylindrical part 32 of the fifth grid... Flat cylindrical part 33... Large diameter cylindrical part 34 of the sixth grid... Support plate 35... Insulating support member 36... Support piece 37...Support piece k...Cathode
Gl...First grid G2...Second grid G
3...Third grid G4...Fourth grid G5
...5th grid G6...6th grid

Claims (1)

[Claims] An electron beam forming section consisting of a cathode and a plurality of electrodes that control electron emission from the cathode and focus the emitted electrons to form an electron beam; a main electron lens section consisting of a plurality of electrodes that focuses an electron beam on a phosphor screen;
In a cathode ray tube electron gun in which a cathode and a plurality of electrodes forming the electron beam forming section and the main electron lens section are integrally fixed by an insulating support member via support pieces provided on the cathode and the plurality of electrodes, The main electron lens part has a large diameter cylindrical part on the phosphor screen side, and a flat cylindrical part having a maximum diameter smaller than the large diameter cylindrical part is integrally formed on the cathode side of the large diameter cylindrical part. formed by a first electrode and a second electrode having a large diameter cylindrical portion surrounding the large diameter cylindrical portion of the first electrode,
The first electrode is provided with a support piece fixed to the insulating support member on the long side of the flat cylindrical portion, and the second electrode is provided with a support piece fixed to the insulating support member on the long side of the flat cylindrical portion, and the second electrode is provided with a support piece fixed to the large diameter cylindrical portion at the maximum of the flat cylindrical portion of the first electrode. A pair of support plates are attached to cover the diameter portion, and support pieces fixed to the insulating support member are provided on the pair of support plates so as to sandwich the support piece of the first electrode from both sides. An electron gun for cathode ray tubes.