JPS6357905B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a television image projection image using an enlarged projection method (it does not matter whether the viewer selects a reflected image or a transmitted image of the image formed on the screen). Regarding the improvement of the projection cathode ray tube that constitutes the source, in particular, it is important to improve the performance of the cathode ray tube itself by improving optical precision, and to reduce the manufacturing process and save money while ensuring the necessary strength by rationally simplifying the structure. The purpose of this is to reduce the number of parts, eliminate the need for adjustments, and reduce the overall cost of the device. A typical conventional example of this type of projection cathode ray tube is disclosed in Japanese Patent Application Laid-open No. 52232/1983. Figure 1 shows
A cross-sectional view of the main parts is shown for an overview. Such a projection cathode ray tube usually has a funnel part 1 connected to a neck part 10 for mounting a deflection coil for a single electron gun.
1, a face plate 12, and a tapered cylindrical portion 13 connecting the two.
4, and a target 15 sealed and fixed in the container.
It is composed of a concave mirror 16, a supporting frame 17 thereof, and a heat dissipating metal (cylindrical cylinder) integral with the target surface, and a Schmitt plate 18 is normally disposed in front of the face plate. In such a conventional example, via the support frame 17,
Before sealing the vacuum container 14, the target and the concave mirror must be supported and fixed with considerable precision at the center of the electron beam or at the optical center of the image to be imaged on the target surface, and the optical This has become a bottleneck in improving precision, eliminating the need for equipment adjustments, reducing processes, and reducing parts. The present invention aims to improve the drawbacks of such conventional examples. As one such improvement, a structure in which a metal such as aluminum is vapor-deposited on the inner surface of the funnel portion having a curvature similar to that of a concave mirror, and the vapor-deposited surface is made into a Schmidt mirror (that is, equivalent to the above-mentioned concave mirror 16) is as follows. This has already been proposed by the same applicant as the present case (Japanese Patent Application Laid-Open No. 53-21523). However, even in such a case, the optical accuracy is largely dependent on the accuracy with which the target surface is fixed in the vacuum container, and it cannot be said that the optical accuracy has been sufficiently improved. In view of this, as shown in an exploded perspective view in FIG. 2, the face plate 23 with the target surface 22 formed on the central metal mounting surface is formed of convex glass of equal thickness, and its center of curvature is aligned with the funnel portion 24. By arranging the cylindrical casing 25 so as to coincide with the center of curvature 0 to form a so-called spherical seat, the open end surfaces 26, 26 of the cylindrical casing 25 following the funnel portion 24 also have the same curvature as the face plate 23. It is also conceivable to grind and polish the face plate 23 so that the face plate 23 is in contact with the open end surface in the normal direction thereof, and then seal the face plate 23 with welded glass or the like. With such a configuration, even if the face plate 23 is slightly shifted and comes into contact with the open end surface of the cylindrical housing 25, the concave mirror 27 formed by the face plate 23, the target surface, and the inner surface of the funnel will still be able to hold the spherical seat. However, since the center of curvature of both remains at point 0, it does not affect the accuracy of the optical system. However, in such an example, variations in the thickness of the fused glass, that is, the thickness of the bonding layer between the face plate and the open end surface, affect optical accuracy and cause a decrease in manufacturing yield. Even when welding the part 24 or sealing the funnel part 24 and the cylindrical casing, it is essential to pay close attention to the welding thickness, which has become a bottleneck in reducing process steps. Also, anode 29 and anode terminal 3
Since the anode lead 31 to which 0 was connected was suspended in the vacuum container, great care was required during manufacturing and handling. For this reason, projection cathode ray tubes shown in FIGS. 3 to 5 have been considered. This projection cathode ray tube has a rigid metal casing 50 that is roughly divided into a funnel part 51 and a cylindrical part 52.
, a face plate 60 made of convex glass of equal thickness, a neck tube 70 and a shim plate 80. The configurations of the network tube 70 and the Schmitt plate 80 are the same as the conventional ones except for the fact that the former is equipped with a high-brightness type electron gun and the structure for attaching it to the funnel. I will omit the explanation as it is not very relevant. The rigid metal casing 50 has an inner surface in the shape of a concave reflecting mirror, and by vapor-depositing chromium or aluminum on the inner surface, the rigid metal casing 50 has a spherical seat configuration that shares the center of curvature with the face plate 60 as a concave mirror 53. A method may be adopted in which the concave mirror 53 is formed integrally with the cylindrical portion 52 or separately and sealed and welded before rough polishing of the concave mirror 53. The inner surface of the funnel portion may be mirror-polished around the center of curvature to form a concave mirror, thereby increasing the precision of the curvature, thereby omitting the step of depositing chrome, aluminum, or the like. As will be described later, the rigid metal casing 50 is connected via a strip of foil 63 to a metal layer 62 such as aluminum deposited on the lower layer of the target surface 61, that is, on the center of the inner surface (convex surface) of the face plate. Since it is conductively connected and functions as an anode lead wire, it is made of Teflon (tetrafluoroethylene), silicone rubber, 1-2 polybutadiene, etc., except for the part where the lead wire with the anode cap 90 for high voltage supply is connected. Cover with insulating resin. The rigid metal housing 50 and the face plate 60
It is necessary that the temperature coefficients are substantially the same, and that even if it expands due to the ambient temperature and the temperature generated from the inside, it does not particularly affect the sealed portion. In order to improve the connection accuracy between the neck tube 70 and the funnel portion 51 of the rigid metal casing 50 , a stem 100 as shown in a sectional view of the main part in FIG. 5A is used. The stem 100 can be a rigid metal body made of a so-called 42-6 alloy of Cr: 42% by weight, Ni: 6% by weight, and Fe (remainder), and basically the bottom outer surface 10
1 has a bottomed double cylindrical shape formed with the same curvature so as to be in close contact with the outer surface of the funnel part 51, and one of the two inner and outer cylindrical parts 102 and 103 (inner in the embodiment) On the inner surface of the cylindrical portion 102 of , there are at least three locations at equal intervals (120° intervals),
Projection 10 for positioning the neck tube 70
4,104 are integrated. In order to secure the stem 100 to the opening 54 of the funnel portion 51 of the rigid metal cylinder 50 with high precision, an aluminum die-casting jig may be used to define the positional relationship between the two. This jig includes a funnel part inner surface abutting part that forms a part of a spherical surface based on the center of curvature of the funnel part 51, a cylindrical part having an outer diameter approximately equal to the inner diameter of the cylindrical part 52, and the cylindrical part. and a line connecting the center of the concave mirror formed by the inner surface of the funnel part 51 and the center of curvature 0,
The rigid metal housing 50 and the stem 100 can be accurately positioned and fixed by being made of aluminum die-casting, which is integrally provided with a stem positioning cylinder having an outer diameter equal to the inner diameter of the stem 100. By welding or brazing the stem 100 in this fixed state, the protrusions 104, 104, etc. of the stem 100 will connect the neck tube 7.
At the same time, the inner diameter end 71 of the open end of the neck tube 70, which has been accurately cut on a plane perpendicular to the center of the tube, is held in contact with the bottom 105 of the stem 100. If the neck tube 70 is oxidized inside and then fixed with a sealing glass 106 such as frit glass, the neck tube 70 can be fixed to the funnel portion 51 with a predetermined precision. When the stem is oxidized in advance and welded to the funnel part, it is essential to take care to prevent the oxide film from being affected by the welding heat. on the other hand,
A separate collar ring 120 is used to ensure that the open end of the rigid metal cylindrical portion 52 and the face plate 60 are joined and sealed without being affected by the thickness of the adhesive such as frit glass. The collar ring 120 is
A cylindrical part 121, which can be made of Ni-Cr-Fe rigid metal, has an inner diameter equal to the outer diameter of the cylindrical part 52, and a cylindrical part 121 having a taper approximately parallel to the tangential direction of the peripheral edge of the face plate 60 . skirt portion 12 extending to
2, and at least three protrusions 123, 123 arranged at approximately equal intervals on the skirt portion. The height of the protrusion is equal to the height of the skirt portion 122.
Care is taken to ensure that the sealing agent (for example, fritted glass) 124 interposed between the face plate 60 and the face plate 60 has sufficient bonding and fixing ability and can withstand shearing force. As described above, the face plate 60 has a common center of curvature with the concave mirror 53 formed on the inner surface of the funnel portion 51, so the inner surface of the funnel portion 51 is polished (ground if necessary) around the center of curvature 0, and the protrusions are polished. If the tips of the parts 123, 123 are also polished (ground), even if the contact between the tips 123 of each protruding part and the convex surface of the face plate 60 deviates, they form spherical seats, so there is no possibility that the optical accuracy will be distorted. do not have. A metal anode surface is deposited on the central part of the inner surface of the face plate made of glass of equal thickness whose curvature has been determined as described above, and the desired red, blue, and
Alternatively, a hard-to-saturate phosphor that emits green light is evenly coated. One end of the vapor-deposited metal is
It has a cross-sectional area (particularly width) that can withstand high pressure, extends to the periphery of the face plate 60 , and is configured to abut on one or more protrusions provided on the skirt portion of the collar ring 120, thereby functioning as an anode lead wire. Configure as appropriate. As mentioned above, the protrusion 123,1
23 and the peripheral edge of the face plate 60 are brought into contact with each other, and the flange ring 120 fixedly sealed to the rigid metal housing 50 and the face plate 60 are melt-sealed with flint glass or the like to form a housing container. By creating a vacuum inside, a projection image pickup tube with consistent optical accuracy can be realized. However, in the examples shown in FIGS. 3 and 4, the face plate 60 has an inner concave shape with equal thickness, so that
External pressure is applied in the normal direction of the face plate,
As a result, shearing force is applied to the sealing portion 124, so
This can cause vacuum leaks over time, shortening the lifespan of cathode rays. In other words, the spherical seat configuration for ensuring optical precision becomes the color for ensuring the life of the tube. In order to improve such drawbacks, in the present invention, a curved surface (spherical seat) processing R is applied to the peripheral edge of the flat disk glass, and the curvature is made to match that of the face plate 60 , which is a characteristic of the spherical seat structure. Face plate 60 ' while ensuring optical accuracy.
The purpose is to change the direction of such external air pressure and prevent large shearing forces from being generated at the sealing portion between the face plate 60' and the flange ring 120. FIGS. 6A and 6B, FIGS. 7 and 8 show first, second and third embodiments of the present invention. The differences in the target surfaces in the embodiments shown in FIGS. 6-8 are as follows. In Fig. 6A, a part of a watch glass-shaped glass sphere is cut out, with a metal such as A being vapor-deposited on the surface and a difficult-to-saturate phosphor coated thereon to form a desired target surface 61'. This is fixed as a target block 66 to the center of the face plate 60 ' with a frit glass 65. As shown in FIG. 6B, both can be made coaxial by machining the upper (tube inner side) peripheral edge of the glass disk with the center 0' of the curved surface of the target block 66 as a reference. 0'' indicates the center of the spherical seat processing. Fig. 7 shows an example in which the target surface 61'' is made of a truncated spherical sealing metal in consideration of the heat dissipation effect, and the curvature of the surface is This is approximately the same as the example shown in the figure. Note that the attachment to the face plate 60 ' is carried out using fritted glass, as described above. In the embodiment of FIG. 8, the rivet-like A
A target surface 61 is formed on the head 166 of the block, and its base 166 is fitted into a through hole with a slightly larger diameter provided in the center of the glass disk and sealed with flint glass or the like. With such a configuration, although the number of processing steps increases somewhat, the heat dissipation effect of the target surface is significantly improved. Target surface processing and face plate 6
The method of machining the spherical seat around the periphery of 0' is similar to the embodiment shown in FIG. According to the present invention, it is possible to realize a long-life projection cathode ray tube with no variation in optical precision and little deterioration due to external pressure. Not only can it be set at any position in the metal casing 50 , but it can also considerably shield X-ray radiation, which should be taken care of in high-brightness cathode ray tubes.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 are drawings showing different conventional examples. FIG. 3 is a perspective view of an example for explaining the problem of the present invention, FIG. 4 is a vertical cross-sectional view of a portion thereof, and FIG.
The figure is also a sectional view of a part thereof. FIG. 6 shows a first embodiment of the invention, FIG. 7 shows a second embodiment of the invention, and FIG. 8 shows a third embodiment of the invention. 50 ...Rigid metal casing, 51...Funnel portion, 60 ...Face plate, 100...Stem, 120...Brim ring.

Claims (1)

[Scope of Claims] 1. A housing in which a cylindrical part and a funnel part each having an open end are formed of rigid metal; It is formed of flat glass of basically the same thickness and has a curved surface on the periphery having a center of curvature that coincides with the center of curvature of the inner surface of the funnel portion, which also serves as a face plate formed with a metal film surface with a target surface provided thereon; and a neck portion formed of a glass tube equipped with an electron gun and fixed to the back surface of the funnel portion; A projection cathode ray tube characterized in that a conductive connection between the casing and the metal film surface is established by sealing the face plate with the curved peripheral portion of the face plate in contact with each other. .