JPS6346951B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a projection cathode ray tube constituting an enlarged projection type television image projection image source.
In particular, we aim to improve the performance of the cathode ray tube itself by improving its optical precision, to reduce the manufacturing process and parts by rationally simplifying the structure, and to make the equipment unnecessary and cost-effective overall. The purpose is to 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 projection cathode ray tubes are usually made of glass and consist of a funnel part 2 connected to a neck part 1 equipped with a single electron gun and a deflection coil, a face plate 3, and a tapered cylindrical part 4 connecting the two. It consists of a vacuum container 10 , a target 11 sealed and fixed in the container, a concave mirror 12, a support frame 13 for them, and a heat dissipating metal (cylindrical) integral with the target surface. A Schmitt plate 14 is arranged. In such a conventional example, via the support frame 13,
Before sealing the vacuum container 10 , not only must the target and the concave mirror be supported and fixed with considerable precision at the center of the electron beam, or the optical center of the image to be imaged on the target surface, respectively. However, it was essential to improve optical accuracy by suspending the anode lead inside the container, and it also became a bottleneck in eliminating the need for adjustments and reducing process and component parts of the device after completion.
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 12) 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, a face plate 20 with a target surface 21 formed on the central metal vapor deposition surface is formed of convex glass of equal thickness, as shown in FIG. 2 as a side view of the main part and as shown in FIG. 3 as an exploded perspective view. At the same time, by arranging the center of curvature to match the center of curvature O of the inner surface 22 of the funnel portion, a so-called spherical seat is formed. , 25 are ground and polished so that they have the same curvature as the face plate 20, and the face plate 20 is held in contact with the open end surface in its normal direction, and then sealed with welded glass or the like. can also be considered. With such a configuration, even if the face plate 20 is slightly shifted and comes into contact with the open end surface of the cylindrical housing 24, the concave mirror 22 formed by the face plate 20, the target surface, and the funnel inner surface will still be able to maintain its position on the spherical seat. form,
Since both centers of curvature are still at point O, the precision of the optical system is not affected. 27 is
A lead wire connecting the anode 28 and the anode terminal 29 is suspended in the vacuum container with some margin. 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 23 or sealing the funnel part 23 and the cylindrical casing, it is essential to pay close attention to the welding thickness, which has become a bottleneck in reducing process steps. The present invention has been made in view of the various drawbacks of the conventional examples. The details are shown below in FIG. 4 showing a perspective view of one embodiment and in FIG.
Figure 6, which shows a central vertical sectional view of the face plate and neck part fixed to such a housing, Figure 7 A and B, which shows an enlarged view of the main parts of Figure 6, and mounting jig and position. Details will be explained with reference to FIG. 8, which illustrates the adjustment method, and FIG. 9, which shows an exploded perspective view. The projection cathode ray tube of the present invention is roughly divided into a rigid metal housing 30 forming a funnel part 31 and a cylindrical part 32, a face plate 40 made of convex glass of equal thickness, a neck tube 50 , and a Schmitt plate 60. However, the configurations of the network part 50 and the emitter plate 60 are the same as the conventional ones except that the former is equipped with a high-intensity type electron gun and the structure for attaching it to the funnel part. Since this goes beyond the gist of the present invention, its explanation will be omitted. The funnel portion 31 has an inner surface 34 in the shape of a concave reflecting mirror, and is made to function as a concave mirror of the Schmidt optical system by vapor depositing Cr or A1 or simply by polishing, and shares the center of curvature with the face plate 40 . When forming the casing 30 by adopting a so-called spherical seat structure, a method may be adopted in which the casing 30 is welded and sealed 33 as an integral part or as separate parts before rough polishing. By polishing the inner surface of the funnel portion to a concave mirror around the center of curvature to simultaneously improve the precision of the curvature, the process of vapor deposition of chromium, aluminum, etc. as described above can be omitted. As will be described later, the rigid metal housing 30 is conductively connected 43 to an anode 42 formed of a metal layer such as aluminum deposited on the lower layer of the target surface 41, that is, the center of the inner surface (convex surface) of the face plate, and is connected to an anode lead. Because it functions as a high pressure supply, Teflon (tetrafluoroethylene),
Cover with insulating resin such as silicone rubber or 1-2 polybutadiene. It is necessary that the temperature coefficients of the rigid metal housing 30 and the face plate 40 are substantially the same, and that even if they expand due to the ambient temperature and the temperature generated from the inside, it does not particularly affect the sealing parts, etc. . In order to improve the accuracy of connection between the neck tube 50 and the funnel portion 31 of the rigid metal casing 30 , a stem 70 as shown in a sectional view of the main part in FIG. 7A is used.
The structure of the stem is specified in FIGS. 5-8. This stem 70 has Cr: 42% by weight,
A rigid metal body made of a so-called 42-6 alloy containing Ni: 6% by weight and Fe (remainder) can be used, and basically it is formed to have the same curvature so that the bottom outer surface 71 is in close contact with the outer surface of the funnel section 31. It has a double cylindrical shape with a bottom, and on the inner surface of the cylindrical portion 72 of one of the two inner and outer cylindrical portions 72 and 73 (inner in the embodiment), at least three locations are provided at equal intervals (120° intervals). , has a structure in which protrusions 74 and 75 for positioning the neck tube 50 are integrally provided. In order to secure the stem 70 to the opening 35 of the funnel portion 31 of the rigid metal cylinder 30 with high precision, a jig 80 as shown in FIG. 8 is used. This jig includes a funnel portion inner surface abutting portion 81 based on the center of curvature of the funnel portion 31;
The cylindrical portion 82 has an outer diameter approximately equal to the inner diameter of the cylindrical portion 32 and the center of the concave mirror formed by the inner surface of the funnel portion 31 and a line connecting the center of curvature O and has an outer diameter equal to the inner diameter of the stem 70 . The rigid metal housing 30 and the stem 70 can be accurately positioned and fixed as shown in FIG. By welding or brazing in this fixed state, the protrusions 74, 75, etc. of the stem 70 can be held in contact with the inner surface of the neck tube 50 , and can be accurately cut in a plane perpendicular to the tube center axis. Netsuku tube 50
The inner diameter end 51 of the open end (see Fig. 7A) is held in contact with the bottom part 73 of the stem 70, and after being oxidized in a wet hydrogen furnace, it is fixed with a sealing glass such as frit glass. , network tube 50
can be fixed to the funnel portion 31 with a predetermined precision. Note that when the stem is oxidized in advance and welded 76 to the funnel portion 31, it is essential to take care to prevent the oxide film from being affected by the welding heat. Next, when sealing the open end (on the face plate side) of the rigid metallic cylindrical portion 32 and the face plate 40 , it is important not to be affected by the thickness of the adhesive such as fritted glass as in the conventional example. To do this, a separate collar ring 90 is used. The collar ring 90 may be made of Ni-Cr-Fe rigid metal, and includes a cylindrical portion 91 whose inner diameter is equal to the outer diameter of the cylindrical portion 32, and a taper substantially parallel to the tangential direction of the peripheral edge of the face plate 40 . A skirt portion 92 that extends outward while holding the skirt portion, and at least three protrusions 93, 94, 95 arranged at approximately equal intervals on the skirt portion.
Consists of etc. The height of the protrusion is determined by ensuring that the sealing agent (for example, fritted glass 96) interposed between the skirt portion 92 and the face plate 40 has sufficient bonding and fixing ability, and that it is resistant to shearing force caused by external pressure applied to the face plate. Since the face plate 40 shares the center of curvature with the concave mirror 34 formed on the inner surface of the funnel portion 31 as described above, the inner surface of the funnel portion 31 is polished (centered around the center of curvature O). If necessary, the tips of the protrusions 93, 94, 95, etc. are also polished (grinded), so that even if the contact between each protrusion and the convex surface of the face plate 40 is misaligned, they constitute a spherical seat, so that optical A metal anode surface is deposited on the central part of the inner surface of the face plate, which is made of glass of equal thickness and whose curvature has been determined as described above, and the desired red and blue colors are deposited on it. or a hard-to-saturate phosphor that emits green light is evenly coated.One end of the vapor-deposited metal is made to have a cross-sectional area (particularly width) that can withstand high pressure, and is attached to the periphery of the face plate 40 . It is configured to extend and come into contact with one or more protrusions provided on the skirt portion of the collar ring 90 to function as an anode lead wire.As described above, the protrusions 93, 94, 95, etc. and the face plate 40 With the peripheral edges of the two in contact with each other,
If the flange ring 90 fixedly sealed to the rigid metal casing 30 and the face plate 40 are sealed with frit glass or the like and the inside of the casing is evacuated, projection with uniform optical accuracy can be achieved. cathode ray tube. Furthermore, the position at which high pressure is supplied via the anode cap 44 can be set at any position in the rigid metal housing 30 , and X-ray radiation, which should be taken care of in high-brightness cathode ray tubes, can be shielded to a considerable extent. There is no need to suspend the high voltage lead wire inside the vacuum container.
Further, according to the present invention as described above, it is possible to realize a projection cathode ray tube that is inexpensive and highly reliable without variations in optical accuracy.

[Brief explanation of drawings]

1 and 2 are sectional views of main parts of different conventional examples, and FIG. 3 is an exploded perspective view of the conventional example shown in FIG. 2. 4 to 9 relate to the present invention,
Fig. 4 is a perspective view, Fig. 5 is a longitudinal cross-sectional view of a portion, Fig. 6 is a longitudinal cross-sectional view of the main part, Fig. 7 A is a cross-sectional view of the neck tube sealing part, and Fig. 7 B is a cross-sectional view of the face plate and collar. FIG. 8 is an enlarged view of the sealed portion of the body, FIG. 8 is a drawing illustrating a mounting jig and a position adjustment method, and FIG. 9 is an exploded perspective view. 30 ... Rigid metal casing, 31... Funnel part, 3
2... Cylindrical part, 90 ... Flange body, 40 ... Face plate.

Claims (1)

[Claims] 1. A flange ring having at least three protrusions arranged at approximately equal intervals on the skirt part is fixed to the open end of the cylindrical part of a housing in which the cylindrical part and the funnel part are formed of rigid metal, and a concave mirror is formed. A metal film surface is formed of glass of equal thickness so that the center of curvature matches the center of curvature of the inner surface of the funnel, and at least a part of the inner surface reaches the periphery and a target surface is provided in the center. A conductive connection between the cylindrical portion and the metal film surface is established by abutting a portion of the formed face plate that reaches the periphery of the metal film surface against the protrusion. Cathode ray tube for projection.