DK152466B - WRAPPING FOR USE IN A PROJECTION CAR POWER AND PROCEDURES FOR PRODUCING IT. - Google Patents

Description

The present invention relates to an enclosure for a projection television tube as set forth in the preamble of claim 1, and to a method of manufacture thereof as set forth in the preamble of claim 22.

Projection television is a well-established technique. However, due to the high cost of manufacturing the projection television tubes used, projection television has generally been limited to costly, complicated and large screen units, which are both difficult to install and expensive to maintain in a satisfactory manner. Thus, the complexity and cost of the currently available projection television tubes has significantly reduced the development and deployment of projection television systems such as home entertainment, an application which could represent a very large market.

Projection television systems for color projection usually comprise three tubes of projection apices in each color (usually referred to as red, green and blue), which images are superimposed in succession on a common image screen. The most effective of such tubes typically comprises the optics of a Schmidt-type projection system and has a target illuminated in a single color by a suitable separate light blank, such as an electron beam grating, a spherical reflector which directs the light around the target's peripheral, as well as a correction lens for any spherical aberration.

In these pipes, certain dimensions are critical. This relationship has given rise to the high construction costs of the projection tube enclosures to achieve high reliability optical properties at the soundness and reproducibility level. It is particularly important that the distance between the mirror surface and the target surface be set and maintained at a predetermined value within approx. ± 0.025-0.050 mm. Projection tubes of the prior art have therefore been constructed with costly and complicated means to position both the target during the manufacture of the enclosure and the tube, as well as adjust its position during both manufacture and installation. A relatively early way to obtain a partial solution to this problem was to mount the mirror in the tube enclosure by forming the mirror on the inner enclosure surface facing the target surface. This, however, still necessitated the maintenance of critical dimensions for more than one enclosure component, as well as an exact positioning of the components, see, for example, U.S. Patent Nos. 2,467,462 and 2,637,829. As this technique has advanced in its evolution, more and more complicated mechanisms have been incorporated into the tube enclosure and combined with it to achieve and maintain the necessary alignment and critical distance between the mirror and target.

It is thus clear that it would be highly desirable to be able to provide an enclosure for a projection television tube, which enclosure is relatively simple in construction, yet capable of being obtained and capable of maintaining the required precise distance in the space between the mirrors. and target surfaces.

The object of the present invention is therefore to provide an improved enclosure for a projection television tube, which enclosure is relatively simple to manufacture, and which encapsulation thus provides the opportunity to provide less expensive components for a projection television system.

This is achieved by the enclosure of claim 1. This peculiarity is convenient in that the enclosure components are utilized as the only means of positioning the target with respect to the mirror, whereby only a single component of the tube enclosure needs to be manufactured with a very accurate dimension. With this enclosure for a television tube, no means is required for setting the target surface position, neither during the manufacture of the tube nor when installing the tubes in a projection television system. The mounting of a projection television tube comprising this enclosure is further facilitated by allowing certain minor variations in the target position relative to the mirror surface which may be required in a projection television system to compensate for the required positioning of each of the three projection tubes in a group relative to the projection screen used.

Another object of the invention is to provide an improved method of manufacturing an enclosure for a projection television tube.

This is achieved by the method of claim 22. This method is convenient in that only one dimension of a tube enclosure component other than optical components needs to be manufactured with great precision. In such a method, the cost of the resulting projection television tube can be substantially reduced by reducing the cost of the component parts used for the enclosure and the cost of the enclosure composition. Further objects of the invention are partly obvious and will be apparent from the following.

Thus, the enclosure of the invention comprises an end plate whose inner surface defines a spherically shaped mirror, a cylindrical member which is attached to the end plate and terminates in an annular front pad end which is so shaped and located that the center of curvature of a sphere, as in a stable position rests on the connecting end, which will substantially coincide with the center of curvature of the sphere defining the mirror surface, target bearing members engaging the connecting end, which members carry a target defining a spherical surface whose center of curvature coincides with the center of curvature thereof. sphere which determines the shape of the faceplate end, as well as a faceplate connected to the cylindrical member.

The sphere which determines the surface of the target and the sphere which determines the shape of the connecting end of the cylindrical element have substantially the same radii, and in a preferred embodiment, the front plate acts as the target supporting element.

Further suitable embodiments are set forth in the subclaims.

The enclosure according to the invention is suitably used for a projection television tube which comprises an end plate whose inner surface defines a spherically shaped mirror, a neck connected to the end plate, a cylindrical member which is attached to the end plate and terminates in an annular front panel end which is thus formed and located that the radius of curvature of a sphere which rests in a stable position on the connecting end substantially coincides with the center of curvature of the sphere defining the mirror surface, target bearing members engaging the connecting end, which means carrying a target defining a spherical surface with a center of curvature which substantially coincides with the center of curvature of the sphere which determines the shape of the front panel to the end of the end, a front plate connected to the cylindrical element, connecting means for electrically connecting the target and the mirror and providing an external anode connection, in the neck enclosed electr on-gun means adapted to produce an e-electron beam for printing a screen on the target, as well as electron beam focusing means.

The process of the invention for the preparation of a

Things for a projection television tube comprise the measures to produce an end plate with a spherically shaped mirror on the inner surface of the end plate, to attach to the end plate a cylindrical member which terminates in an annular front pad end which is so formed and located that the center of curvature of a sphere such as in stable position rests on the connector end, substantially coincides with the center of curvature of the sphere defining the mirror surface, to place on the frontal pad end end of the cylindrical element a target supporting member designed to engage the front pad end and to carry a target defining a spherical surface with such a center of curvature that it substantially coincides with the center of curvature of the sphere which determines the shape of the front panel end, whereby the placement of the target supporting member in conjunction with the height of the cylindrical member serves to achieve a predetermined position for the target with respect to the mirror, as well as connecting the faceplate to the cylindrical member, thereby permanently fixing the target in the predetermined position.

By this method, a simplified manufacture of a projection television tube is obtained, which can then be accomplished by producing an end plate with a spherically shaped mirror on the inner surface of the plate, connecting a neck to the end plate, providing a cylindrical member terminating in an annular front panel connection, which is so designed and located that the center of curvature of a sphere which rests in a stable position on the connection end substantially coincides with the center of curvature of the sphere defining the mirror surface, to impose an electrically conductive coating on the inner wall of the cylindrical element, connecting an end connection through the wall of the cylindrical element, placing on the front plate end end of the cylindrical element a target bearing member which is designed to engage the front plate end end and carrying a target defining a spherical surface with a curvature which substantially falls along with the center of curvature of the sphere, so m determines the shape of the front panel connection end, whereby the placement of the target bearing member in conjunction with the height of the cylindrical element serves to achieve a predetermined position of the target with respect to the mirror, to provide a front plate, to attach the end plate to the cylindrical element, to provide an electric connecting the mirror to the target, connecting the front plate to the cylindrical member, thereby permanently fixing the target in its predetermined position, providing an electron gun assembly adapted to direct an electron beam toward the target, enclosing the electron gun assembly in the neck, in such a way that vacuum is created within the volume of the tube, as well as attaching electron beam focusing means to the throat.

Appropriate embodiments of the method will be apparent from the detailed description and the corresponding subclaims.

The invention will now be described in more detail with reference to the drawing, in which: FIG. 1 is a longitudinal section of the enclosure of the invention; FIG. 2 is a plan view of the inner surface of the front plate of the tube enclosure of FIG. 1, FIG. 3 is a perspective view showing the projection television tube enclosure assembly of FIG. 1 in a separate state, FIGS. 4-9 are cross sections of different methods of sealing the faceplate and cylindrical sections of the projection television tube enclosure; FIGS. 10 and 11 are views of heat transfer means adapted to cool the target surface; FIGS. 12-14 are longitudinal sections of two further embodiments. the projection television tube enclosure of the invention, wherein the target supporting member comprises a target support attached to the faceplate, FIGS. 15 and 16 longitudinal section through yet another embodiment of a projection television tube enclosure of the invention comprising a separate target supporting member; FIG. 17 is a plan view of the target carrying means used in the embodiment of FIGS. 15 and 16; FIG. 18 is a longitudinal section of a projection television tube constructed in accordance with the present invention and comprising the tube enclosure of FIG. 1, FIG. 19 is a simplified diagram of a projection television system; and FIG. 20 schematically illustrates the effect of a small side displacement of the center in the sphere defining the target surface relative to the mirror surface to compensate the optics of a projection television system.

FIG. 1 and 2 show a preferred embodiment of the projection television tube enclosure according to the invention, and FIG. 3 shows the three components forming the enclosure in separate state. A complete projection television tube comprising the enclosure of FIG. 1-3 are shown in FIG. 18, and will be described later.

A projection television tube enclosure 10 according to the invention is shown in FIG. 1, formed by three main components consisting of an optically transparent front plate 11, a cylinder-like wall element 12 which may be somewhat conical, and an end plate 13 with which a central neck section 14 is joined. In accordance with current practice, the annular inner surface 15 of the end plate 13 (Fig. 3) facing the inner wall of the front plate 11 is formed with the sphere shape of a sphere having a center 16 and a radius Rep. The annular portion of the surface 15 within the enclosure volume 17 is coated, for example, aluminized, to provide a mirror 18. Thus, the mirror 18 may be said to be a spherical segment or to have a spherical shape, which term will be used in the the following to indicate a part with a spherical surface. Of course, it is clear that the mirror 18 is not as thick as shown in FIG. 1. However, the mirror and target surfaces are exaggerated in the drawing to simplify identification.

The inner surface 19 of the neck 14 is coated with a suitable, electrically conductive coating, such as a colloidal graphite coating sold under the trade name "Day". This coating extends up to and in contact with the edge of the mirror 18.

In the Schmidt system, a beam of electrodes is directed to a target blank 20 within a particular target surface area referred to as the screen 21 (Fig. 2). The generally rectangular target flat in its shape must be spherical, ie. be formed with the sphere shape of a sphere having a radius R 1, which center of the sphere substantially coincides with the center 16 of the sphere which defines the shape of the surface of the mirror 18. In this way, the radial distance Dc between the mirror 18 and the target 20 substantially constant. Obtaining and maintaining this distance Dc is critical to the manufacture of the projection television tube enclosure as well as tubes comprising such enclosures.

With the enclosure according to the invention, the safe and accurate positioning of the target 20 to achieve the desired ratio with the mirror 18 is achieved by providing the cylinder-like element (hereinafter referred to as the cylindrical element) with an annular front panel end closure 22 which Thus, it is designed and located relative to the mirror 18 that the center of curvature of a sphere which rests in a stable position on the connection end 22 coincides substantially with the center of curvature of the sphere defining the surface of the mirror 18. As schematically shown in FIG. 1, the connecting end 22 is thus formed with the sphericity of a sphere having a radius R and having a center, as in the

dC

substantially coincides with the center 18 of the sphere with the radius Røp, the latter sphere defining the surface of the mirror 18. Alternatively, the connecting end 22 may be designed to exhibit a surface for positioning and carrying a sphere having a radius R 5, as described in detail below in connection with the description of Figures 6 and 8.

By attaching the target 20 to a target supporting member which engages the connecting end 22 of the cylindrical element 12, the target supporting member and the target fixed thereon can make a small lateral movement along the connecting line without any effective displacement of the target surface relative to to the mirror caused. A lateral movement of the target-carrying element of as much as from ca. 1.25 mm to approx. Thus, 1.75 mm from the correct sealing surface alignment during assembly and closure will not adversely affect the optical properties of the projection tube comprising the enclosure thus constructed, since the critical distance Dc will be maintained.

Thus, in addition to forming part of the enclosure wall, the cylindrical member has the task of precisely positioning the target surface relative to the mirror surface to obtain the desired predetermined distance Dc. This implies that the height of the cylindrical element is the only critical dimension in the pipe enclosure construction. Because the cylindrical member may have a plurality of different cross-sectional shapes, a predetermined height of a cylindrical member may be defined as the cylinder-like member which, when inserted between the end face mirror and the spherical surface of the target member, essentially results in coincidence between the center of curvature of the mirror and the center of curvature of the target. The cylindrical element thus becomes the encapsulation component which serves as the only means to position the target relative to the mirror.

As will be apparent from the detailed description below, the target supporting member may exhibit any of a number of shapes as long as it has a connecting edge designed to engage the connecting end of the cylindrical member, which connecting edge is determined by the surface of the sphere as shown in FIG. its stable position rests on the connecting end 22 of the cylindrical element 12, the center of which essentially coincides with the center 16. Of the mirror 18, in the embodiment of the tube enclosure according to FIG. 1-3, the faceplate 11 serves the dual purpose as a target-bearing element and faceplate, whereby the target is deposited directly on the interior surface of the faceplate 11. The target 20 will typically be formed by deposition under vacuum of an aluminum film on the surface 23, after which the desired phosphorus agent is deposited on aluminum film. As shown in FIG. 2, the actual target area 20 is made somewhat larger in both dimensions than the screen 21 to be printed on the area. For example, it is generally desirable that the target be made from approx. 1.5 mm to approx. 1.75 mm larger than the screen 21 at each of the four sides to compensate for any permissible lateral movement of the target-bearing element in the enclosure composition and closure.

Although for convenience, the target 20 is shown in the drawing with considerable thickness, it is clear that in all practical respects the target may be considered as a surface which coincides with the inner surface 23 of the faceplate 11 or with the surface of another substrate upon which the target a set aside. This then implies that the inner surface 23 of the faceplate 11 and the surface of the target 20 to meet the targeting requirements are also formed with the sphere shape of a sphere which is substantially identical to the sphere with the radius Rs0. Thus, the spherical surfaces defining the faceplate 11 and the target 20 can be seen to have radii and R 2 which are substantially equal to R In the preferred embodiment of FIG. 1-3 of the enclosure, the spherically shaped front plate is thus fixed at the connection end 22 in a suitable manner as shown in Figures 4-6 and 8 to obtain the desired radial distance D between mirror and target.

The FIG. 1-3 of the enclosure is made up of three separate components as shown in FIG. 3. In this case, the front plate 11, the cylindrical member 12 and the end plate 13 with the neck 14 are molded of appropriate glass and machined to form the desired shape of the mirror and connection surfaces. In this encapsulation embodiment, where the cylindrical member 12 is to be attached to the end plate, it is also necessary that the end pad end end 25 of the cylindrical member 12 be shaped to substantially conform to the spherical shape of the mirror 18 or have a surface whose spherical shape substantially fits. to the mirror 18, i.e. Thus, it is clear that the end pad end end of the cylindrical member 12 has a surface formed with the sphere shape of a sphere of radius Rgp.

Of course, although a little taper is generally preferred in the cylindrical member 12, it is also within the scope of the invention to design the cylindrical member in another suitable manner. However, it will be appreciated that the critical dimension Dc is determined by the distance maintained between the target supporting member and the mirror, and that this distance is determined only by the height dimension of the cylindrical element, taking into account, if necessary, the thickness of one or more frets. which is inserted between the components.

Before discussing the various methods that can be used to join the enclosure components, it will be appropriate to complete the description of the remaining elements of the enclosure. In accordance with prior art in the construction of the enclosure, the inside 26 of the cylindrical element 12 is coated with an electrically conductive coating, for example a suitable colloidal graphite coating, and an electrical connection is provided between the mirror 18 and the target 20. This electrical connection comprises a film strip 27 of an electrically conductive material, for example aluminum, which strip is placed on the face 23 of the faceplate in contact with the target 20 (Fig. 2), and the strip is terminated in an extended contact area 28, e.g., a colloidal graphite coated area, and an electric conductive wire 29, for example stainless steel, which is designed to force its indented ends into contact with the region 28 and the mirror surface 18. An outer anode connection 30 is passed through the wall of the cylindrical element 12 and is sealed thereto by means of a insert 31 for contacting the wire 29 through a spring clamp 32 so that there are one of the electrical contacts required for a projection television tube containing the enclosure is provided. Alternatively, this anode connection may be inserted through and sealed in the end plate.

A correction lens 33 is held at a distance from the front plate 11 by a lens carrier 34 which, by abutting the front plate 11, automatically results in the lens 33 being aligned with the other optical components of the tube. The support ring 34 is secured to the housing by means of several separate angularly bent arms 35 which are held on the cylindrical element 12 by an adjustable band 36. The lens 33 not only serves to correct for the naturally spherical aberrations contained in the system's optics, but also serves as protection for the faceplate 11 together with the support 34. The actual design and positioning of the lens 33 will be within the skill of a person skilled in the art, and it will be apparent that a proper selection of correction lenses with slightly different effective strengths can be used to correct for any small dimensional inaccuracies. in the enclosure.

Figures 4-9 illustrate in section several ways in which the faceplate 11, the cylindrical member 12 and the end plate 13 in the embodiment of Figs. 1-3 can be joined together and sealed to each other. In the modification of Figures 5 and 6, the front plate end end 22 of the cylindrical member 12 is ground to have the required spherical shape, and the end pad end 25 is ground to the same spherical shape as the mirror 18. The closure or seal is provided using two fret layers 39 and 40 (typically a commercially available lead oxide free) between the front plate and the cylindrical member, respectively between the cylindrical member and the end plate. In connection with this closure, it is of course necessary to accurately control the thickness of the fryer layers 39 and 40 as well as subtract the total thickness of these frets during a calculation of the height dimension of the cylindrical element 12 which controls the distance D between the target and the mirror.

V

The actual thickness of the fryer layers 39 and 40 can be controlled by using interlayer pieces as in FIG. 5 are shown as small spheres or beads 41 of exact size and made of glass having a melting point sufficiently higher than the activation temperature of the friction material for the beads to retain their original shape during the seal. Of course, it is also desirable that the glass from which the beads 41 are formed have a heat expansion coefficient which is substantially the same as that of the material from which the components of the enclosure are made. Other suitable spacers, such as short glass bars or glass threads of appropriate dimensions, may be used. In general, deep-layer thicknesses are in the range of ca. 0.1 mm and approx. 0.4 mm is preferred. Glass beads with a diameter of 0.25 mm can be given as an example of suitable intermediate members.

Figures 6-9 illustrate several joining or sealing modifications that do not require clearance for frets! when determining and obtaining the desired exact height dimension for the cylindrical member. In the modification of FIG. 6, the surface 22 of the cylindrical member 12 is ground to the desired spherical shape, and then a groove 42 is cut for a free material 43, including care being taken to maintain the integrity of the inner line contact 44 so that it as well as the remaining portion. of the surface 22 forms a sealing surface of the desired spherical shape. On equal

In the same way, the surface 15 of the end plate 13 has a free groove 45 containing a free material 46 which is cut to provide a contact line 47 which together with the remaining part of the surface 15 provides the necessary sealing surface. Alternatively, as shown in FIG. 7, a free groove 48 is cut at the end 25 of the cylindrical member while retaining a portion of the spherical end surface 25 and so that a contact line 49 is formed on the spherical surface of radius R

FIG. 8 illustrates a modification in which two parallel and circular contact lines 50 and 51 are provided on the front plate connecting end 22 of the cylindrical element 12 for abutment against the front plate 11 serving as the target supporting member. Between these contact lines, a fryer space 58 is provided. The two contact lines 50 and 51 must, of course, lie on the required spherical surface with radius Rse corresponding to the surface 22 on the front plate end end of the cylindrical element 12. Thus, these two parallel contact lines 50 and 51 meet the requirement of forming a surface whose spherical shape corresponds to the prescribed sphere with radius R and center 16. Parallel contact lines 53 and 54 which define a fryer space 55 between them can also be cut into the peripheral surface of the end plate 13 to connect the cylindrical element 12 thereto. As shown in FIG. 9, the peripheral surface of the end plate 13 may finally be formed as a substantially flat surface 56 such that the end pad end end 25 of the cylindrical member 12 forms a contact line 57 with the end plate leaving a clearance space 58 for the seal.

As will be seen, several combinations of sealing surfaces can be used in connection with the construction of a projection television tube or tube enclosure according to the invention, provided that the front panel end end surface of the cylindrical element is designed as previously stated.

The design of the faceplate in the projection tube allows the incorporation of external cooling means for the target, and this allows for a higher level of light as well as a longer life for the tube. As shown in FIG. 10 is a profiled plate 60 consisting of a material of relatively high thermal conductivity, for example copper, connected to the front plate 11 in thermal contact with its outer surface 61, and the plate 60 is positioned corresponding to the position of the target 20. A pin 62 extends upwardly from plate 60 in heat transfer contact therewith, and one or more heat dissipating fins 63 are attached to the pin.

FIG. 11 illustrates a modification of the external refrigerants of FIG. 10, the plate 60 being placed in a recess 64 which is cut into the surface of the front plate 61. Since the thickness of the wall of the faceplate through which the heat of the target 20 is transmitted by conduction to the plate 60 is smaller than in the arrangement of FIG. 10, the cooling of target 20 is somewhat more efficient in the arrangement of FIG. 11th

The embodiments of the tube enclosure shown in Figures 12-14 utilize the faceplate as part of the target supporting member while providing flexibility in the tube optics. In the embodiment of the enclosure shown in Figures 12 and 13, where the same reference numerals are used as in Figs. 1 for identifying like elements, the faceplate 11, cylindrical member 12 and end plate 13 are configured in the manner described in FIGS. 1 and 3, and these components are joined and sealed using any suitable technique, such as one of the in connection with Figures 4-9. However, the target 20 deposited in the manner previously described is located on the surface of a substrate or substrate 70, preferably formed of the same glass as the enclosure or of glass having substantially the same coefficient of thermal expansion as the encapsulating glass. The target substrate 70 preferably has two or more feet 71, the surfaces of which 72 are to the abrasive so that they have the same spherical shape as the inner wall 23 of the faceplate 11 for accurate location of the target 20 on the faceplate 11 when the substrate is secured thereto with frets 73 which is supplied in such an amount that a portion of the space between the substrate 70 and the surface 23 is filled. Thus, in this embodiment, the target supporting member consists of the faceplate 11 as well as the target substrate 70 attached thereto.

In the embodiment of FIG. 2, the target cover provides a target 20, the surface of which is assigned a spherical shape corresponding to a ball of radius R 1. and a center substantially coincident with the center 16 of the mirror-forming spherical surface. Although Rt is somewhat larger than Rse, the set conditions of the target's support relative to the mirror are met, since small offsets in the lateral direction of the faceplate 11 as well as the target base 70 attached thereto will in fact have no effect on the radius distance Dc between the target and the mirror.

To provide electrical connection between target 20 and mirror 18, a narrow film 74 of aluminum or other electrically conductive material (Fig. 13) may be deposited starting at the edge of the target and extending along the side and the supporting surface opposite the target surface to provide contact through a conductive terminal 75 with a conductive film 27 deposited on the surface 23 of the faceplate 11 and terminating in a contact area 28 as shown in FIG. 2. The remaining connection through a conductor 29 is identical to that of FIG. 1. Within the scope of the invention, it is of course possible to provide other convenient electrical connections between the target, anode connection and mirror.

The optics of the embodiment of FIG. 12 is arranged so that it is not necessary to use a correction lens since the front plate 11 can serve for this purpose. This is made possible because there is freedom in this arrangement for positioning the faceplate relative to the mirror, and if necessary, the faceplate surfaces can be designed taking into account the mirror surface to enhance its optical corrective properties. Of course, within the scope of the invention, it is also possible to equip the embodiment of FIG. 12 with an appropriately designed correction lens on the one shown in FIG. 1 to provide a projection tube with the highest quality properties.

The projection television tube enclosure of FIG. 14 utilizes a target substrate 80 which is secured by means of frets 81 to a flat front plate 82 as the target bearing member in engagement with the cylindrical element end surface 22. In this embodiment, the peripheral engagement surface 83 of the front plate 82 is to the abrasive to the spherical shape of a ball surface with radius R, and measure below! the yoke 80 is towed to a spherical shape as a sphere of radius Rt, the two spherical faces having centers of curvature which coincide substantially with the center of the sphere of radius Rp defining the mirror surface. It will be appreciated that this embodiment also meets the requirements of the enclosure components.

Use of a substantially flat front plate necessitates, for the sake of good quality, that a correction lens 85 is mounted which is mounted in a lens assembly 86 which is sealed against the outer edge of the front plate 82. The design of the lens 85 is known in the art, and the lens is positioned so that its optical center coincides substantially with the center of the ball surface 16, and during the mounting of the enclosure components, the position of the lens 85 is adjusted by well known and optically observed self-imaging methods.

In the embodiment of the pipe enclosure shown in Figures 15-17, the end plate 90 and the cylindrical element 91 are formed in one piece 92 before the front plate is sealed to the cylindrical element. Thus, the cylindrical member 91 can be flame-sealed to the end plate 90, or these two components may initially be integrally formed. This arrangement is, of course, convenient for any of the embodiments of the pipe enclosure of the invention. Alternatively, the enclosure of FIG. 15 may be constructed with a separate end plate and a cylindrical member as previously described. The embodiment of Figures 15-17 also includes a target bearing member which is separate from and different from the front panel. In this arrangement, the inner face 95 of the cylindrical member 91 front end terminates to the ground to the required spherical shape, that is, the shape of a ball face with radius R $ e, and the outer face 96 is plane ground to carry a flat circle. shaped faceplate 98 sealed by a fret layer (see Fig. 16).

The target carrying member 100 shown in plan view in FIG. 17, in which narrow support lugs 102 extend inwardly to maintain a target support 103, upon which a target 20 forming the screen 21 is disposed. Figures 15-17 show that the target bearing member 100 is formed as a segment of a ball surface of radius R 1. (which is substantially equal to R) to provide the required surface configuration for target 20

tf C

and engagement between the target positioning and seating ring 101, and the spherical surface 95 of the cylindrical member. Thus, by using this spherically shaped target supporting member and the spherically shaped surface 95 (or a surface corresponding to a spherical surface as shown in Fig. 8), the desired positioning of the entire target surface relative to the mirror 18 is ensured. member 100 is preferably formed of stainless steel using well-known etching methods.

In order to maintain a continuous engagement between the target bearing ring 101 and the surface 92, several spring clamps 104 are arranged around the target support between the inner wall 105 of the front plate 98 and the ring 101. If the target supporting member 100 is formed of an electrically conductive material, it may function. alternatively, as the electrical connection between the target and the wire 29. As shown in Figures 16 and 17, the electrical connection between the target and the mirror may alternatively be provided through a thin conductive strip 106 terminating in an extended conductive region 107 and the wire 29 is in contact therewith. area 107 of the enclosure of FIG. 1.

From the above detailed description of examples of embodiments of the projection television tube enclosure according to the invention, it will be seen that many combinations of the target supporting means, enclosure configurations, sealing methods and electrical connections within the tube are possible.

FIG. 18 is a longitudinal section of a projection television tube constructed in accordance with the present invention, that is, a tube containing tube enclosure none according to the invention. The tube enclosure shown in the tube of FIG. 18 corresponds to that shown in Figures 1-3. However, the tube may use any of the embodiments shown or described for the enclosure. In accordance with generally accepted practice of designing projection television tubes, the neck 14 is sealed to provide a fluid-tight and evacuated enclosure volume 17. An electron gun 110 of a well-known device is enclosed in the neck 14 and is shown containing a cathode 111 with associated filament 112. grids 113 and 114 and an anode 115 electrically connected to the anode connection 30 through the electrically conductive coating 19 extending down the inner wall of the neck 14 to contact the anode 115, the mirror 18 and the wire 29. The projection television tube has a magnetic focusing lens assembly 116 , a convergence control means 117 as well as deflection control means 118, all of which are standard components.

In the above detailed description of pipe enclosure and of a projection tube containing an enclosure according to the invention, the curvature centers of the spherical surfaces which determine the contours of the mirror, the target surface and the front panel end end surface of the cylindrical element are stated to be substantially coincident. As used herein, this term should include any combination of locations for these centers which meet the requirement that the radial distance D from a point on the target surface to the mirror surface is a constant value within a predetermined tolerance range that allows the desired optical properties to be obtained. and performance for the pipe. As will be understood, the real curvature centers of the optical elements may be somewhat offset to achieve the optimum optical design that compensates for finite distance work.

In a projection television tube of what could be termed "standard size" and with a radial distance Dc from target to mirror of approx.

10 cm, the tolerance range of the distance D is, for example, from approx. 0.050 mm to approx. 0.10 mm greater or less than the predetermined radial distance. This, in turn, implies that during the mounting and sealing of such a "standard size" tube, a slight displacement of the location of the center of curvature of the ball surface corresponding to the target surface can be tolerated, either upwards or downwards on the tube axis and / or in the lateral direction. away from the axis, which displacement results in a lateral movement of the target supporting member which is not greater than ca. 1.5 to 1.75 mm, away from the perfect alignment.

In a projection television system, which uses three separate projection tubes, namely a tube for projection of the red, blue or green images, a small lateral displacement away from the tube axis is actually needed for the center of curvature which determines the shape of the surface. Of course, it is not physically possible to place three tubes with coincident axes, and the axes cannot be parallel since the images from the three tubes must be coincident and accurately superimposed on the screen. As shown in FIG. 19, it is further necessary to obtain a direct line of sight from the screen 125 to the viewer 126 to align the images of the three tubes included in the projection system 127 at an angle of, for example, 5-10 °. Thus, it is highly desirable that the projection television tube is designed to compensate for these factors.

Such compensation can be readily obtained in connection with the present invention by a small lateral displacement of the target's center of curvature within the previously stated limits. This can be seen in FIG. 20 where the magnitude of the offset shown is exaggerated to better illustrate the effect. It will be seen that as the center 16 of the target surface 20 is displaced to a point 16a, the target surface 20a will also displace, resulting in a small but effective displacement of the beam emitted by the tube, thereby enabling the use of three projection tubes and obtaining a accurate overlay of their images on a screen. Such a small lateral displacement of the target's curvature center will generally be in the range of ca. 0.13 mm to approx. 0.25 mm. Although such a side shift provides the desired beam focus, the offset will not exceed the prescribed tolerance range for the distance Dc. Any subsequent deviation within the established setting limits from the ideal position will not cause any noticeable deterioration within the color television requirements.

The components forming tube enclosure (front plate, cylindrical element, end plate and tube formation for the neck) are preferably formed of electronics glass, the glass in each component having a heat expansion coefficient which is as far as possible the same as for the other components in the enclosure. It is also possible to form the cylindrical element of a ceramic material or of a metal, provided that this also has a heat-expanding coefficient which approximates the coefficient of the glass in the other components.

The method of the invention can be elucidated using the production of the projection television tube of FIG. 18 as an example. The three components of the housing and a piece of pipe to be used as a neck tube are made by casting, and the optical surfaces of the front plate and end plate and also the sealing surfaces of the cylindrical member are sanded and polished to the desired shapes, and the optical surfaces of the components are then finalized. Measure the workpiece, the conductive strip and the final conductive area on the inside of the faceplate. The position of the target within the required area of the front panel surface can be obtained, for example, by using a photosensitive binder in the same way as in the manufacture of television tubes for direct viewing.

The inner surface of the cylindrical member is coated with an opaque, conductive coating, the anode connection is sealed into walls, and the conductive wire is secured. The mirror is deposited on the surface of the end plate, and the electrically conductive coating is applied to the inner neck connection surface of the front plate as well as to the inner surface of the neck tube to a predetermined line. The open neck tube is then flame sealed to the end plate. The required amount of frit is applied to the two connecting ends of the cylindrical element, and the front plate and end plate are placed on the cylindrical element to seal the enclosure by burning in an oven. This positioning is achieved by aligning the outer edges of the front plate with the cylindrical member and by causing the cylindrical member to abut against the end plate to ensure complete and unbroken contact therewith.

In a typical firing and sealing cycle, it takes 45 minutes to bring the enclosure to the free activation temperature of approx. 445 ° C. This activation temperature level is maintained for approx. 30 minutes, after which approx. 1.5 hours to cool. It has been found to be preferable to increase the temperature of the cylindrical member in the vicinity of the faceplate to slightly above, e.g. 30 ° C above, the faceplate temperature during the last part of the heating and during the first part of the heating for free activation in cycle. This can be done by directing infrared radiation locally to that area of the cylindrical element's surface. It is believed that this extra local heating regulates the direction of the induced voltages and thus may contribute to obtaining a stronger tube enclosure.

In accordance with current practice, the components of the electron gun are then flame-sealed in the tube neck, raising the temperature of the tube to between 350 ° C and 400 ° C, electrically activating the cathode, and finally sealing the end of the neck. Finally, the correction lens is applied in the manner previously described and the outer focusing means attached to the neck.

From the above detailed description of the projection television enclosure and of the finished tube, and of the method of manufacturing the enclosure or tube, it will be seen that the present invention provides a significant advance in the art by enabling the manufacture of relatively simple, inexpensive and optically acceptable projection television tubes. This progress is achieved by the configuration of the components forming the tube enclosure and by using these encapsulation components as the only means of positioning the target in relation to the mirror. Furthermore, it is only necessary to produce a single component, namely the cylindrical element, with only one very accurate dimension.

Claims (26)

Enclosure for use in or included in a projection television tube, said enclosure (10) comprising a reflective surface (18) of spherical configuration and having a center of curvature (16) disposed on the projection axis of the tube, a target (20) disposed apart from and in front of it. reflecting surface (18) and containing a target surface (21) lying in a spherical plane concentric with the reflecting surface (18) and on the same side of said curvature center (16) as the reflecting surface (18), the target surface (21 ) intersects the projection axis, a carrier for the target (20), which carrier is disposed between the target surface (21) and the center of curvature (16) of the reflecting surface (18), a front plate (11, 82 or 98) having a rear peripheral edge for sealing and disposed between the target surface (21) and said center of curvature (16), the front plate intersecting the projection axis and a cylindrical or tubular body (12 or 91) having a axis of symmetry coinciding with the projection axis. and extending between an end plate (13 or 90) and said rear peripheral edge of the front plate, and which enclosure is CHARACTERIZED in that the end plate (13 or 90) is of a spherical configuration in which the reflective surface (18) is formed, deposited on or carried directly on the inner surface of the end plate, that the cylindrical or tubular body (12 or 91) is terminated by an annular front pad connection end (22) forming or containing an annular support surface lying in a concentric spherical plane with the reflective surface (18) and with the target surface (21), and AT this annular support surface is joined to a peripheral edge region of said target support member, said peripheral edge region being substantially in the same spherical plane as said annular support surface . Enclosure according to claim 1, characterized in that the target carrier (100) contains a circular positioning and seating (101) having inwardly extending spokes (102) carrying a target under (103), and wherein the ring (101) form said peripheral edge region of the target carrier (Figs. 15 and 17). Enclosure according to claim 2, characterized in that the positioning and seating ring (101) is arranged for engagement with said spherical and annular support surface (95), and wherein the front pad connection end further comprises an outer surface (97) on which the front plate (98) is sealed (Fig. 16). Enclosure according to claim 3, characterized in that the front plate (98) contains means (104) for forcing said ring (101) into engagement with the spherical annular support surface (95). Enclosure according to claim 1, characterized in that the front plate (11 or 82) is included in said target carrier, said rear peripheral sealing edge of said front plate being spherically curved and constituting said peripheral edge region of said target carrier sealed to said annular and spherical curved support surface on the front pad connection end (22). Enclosure according to claim 5, characterized in that the faceplate has a spherically curved inner surface (23) which is substantially in the same spherical plane as the rear peripheral sealing edge of the faceplate and wherein the target (20) is deposited or attached to this inner surface (23) (Figs. 1-3). Encapsulation according to claim 6, characterized in that the target (20) is fixed to the inner surface (23) by means of a target support (70) (Figures 12 and 13). Enclosure according to claim 5, characterized in that the front plate (82) is substantially planar with the exception of the spherically curved peripheral sealing edge (83) thereof, and wherein the front plate (82) carries a spherically shaped target base (80) which substantially concentric with said reflective surface (18) (Fig. 14). Enclosure according to any one of claims 5-8, characterized in that the rear peripheral sealing edge of the front plate (11 or 82) is sealed to said annular support surface on the connecting end (22) of the cylindrical body (12) by means of a fretting layer ( 39) of predetermined thickness. Encapsulation according to claim 9, characterized in that the frying layer (39) contains spacer means (41), such as glass balls, for determining said thickness. Enclosure according to any one of claims 5-8, characterized in that the front panel connection end (22) contains said spherically curved annular support surface combined with a fret groove (42) cut to produce a contact line (44) or parallel contact lines (50, 51) with an intermediate frying groove (50). Enclosure according to any one of claims 1-11, characterized in that the cylindrical body (91) and the end plate (90) are formed as a continuous piece (92). Enclosure according to any one of claims 1-11, characterized in that the cylindrical body (12) is separated from the end plate (13) and is sealed thereto along an end pad connection end (25) of the body (12). Encapsulation according to claim 13, characterized in that the end-plate connection end (25) has a spherical shape which is substantially identical to the shape of the reflecting surface (18). Encapsulation according to claim 13 or 14, characterized in that the end plate is sealed to the cylindrical body by means of a fret layer (40) of predetermined thickness. Encapsulation according to claim 15, characterized in that the frying layer (40) contains spacer means (41), such as glass balls, for determining said thickness. Encapsulation according to claim 13 or 14, characterized in that the end plate has a peripheral sealing edge which contains a free groove (45 or 55) cut to produce a contact line (47) or parallel contact lines (53, 54). An enclosure according to claim 14, characterized in that the end plate (13) has a flat peripheral edge, an inner restriction thereof being arranged to form a contact line (57) with the inner wall of the cylindrical body (12), which plane peripheral edge forming a fryer (58) between its surface and said spherical connecting end (25). Enclosure according to any one of claims 5-18, characterized in that heat conduction means are attached to said target (20) on the front plate (11). Encapsulation according to claim 19, characterized in that the heat dissipating means contain a heat conducting plate (60) which is fixed to the outer surface (61) of the front plate in a position corresponding to the target (20), and heat exchanger surfaces (62, 63) arranged to conduct heat from the target and through the faceplate to the surrounding atmosphere. Enclosure according to claim 20, characterized in that said plate (60) is recessed into a recess (64) in the front plate (11). A method of manufacturing an enclosure according to any one of claims 1-21 for a projection television tube, CHARACTERIZED in the design of a spherical end plate (13) having an inner reflecting surface (18) located in a spherical curved plane with a curvature center ( 16) positioned in front of the end plate of the projection axis of the tube, an attachment of the spherical end plate (13) to a cylindrical or tubular body (12) of predetermined length and with a axis of symmetry coinciding with the projection axis, and wherein said body (12) ) is provided with an annular connection or seal end (22), at least part of which lies in a spherical plane which is concentric with the reflecting surface (18) and located on the same side of the center of curvature (16) as the reflecting surface an arrangement on the spherical sealing end (22) of a peripheral edge region of a target carrier, said edge region being substantially in the same spherically curved plane as the sphere sealing or connecting end or end portion (22) and sealing a front plate (11) of the annular to end end (22) of the cylindrical body (12) thereby permanently securing said target support member in such a position that it carries a spherical shaped target surface (21) which is concentric to the reflecting surface (18) and located on the same side of said center of curvature (16) as the reflecting surface. The method of claim 22, characterized in that the attachment of the cylindrical body to the end plate comprises a flame seal of the cylindrical body to the spherical end plate or a molding of the cylindrical body integrally with the end plate. 24. A method according to claim 22, characterized in that the sealing of the front plate to the cylindrical body and the attachment of the cylindrical body to the end plate are carried out simultaneously by the use of freely inlaid between surfaces to be connected or sealed, and includes a configuration of an arrangement, containing the faceplate, the cylindrical body and the end plate with frit, as well as exposing this arrangement to a heating cycle containing heating-free activation and cooling periods. The method of claim 24, characterized in that the temperature of the cylindrical body near its sealing end (22) is maintained at a temperature above, such as 30 ° above, the temperature at which the faceplate is maintained during the latter part of the heating period. and during the first part of the free activation period of said heating cycle. Method according to any one of claims 22-25, characterized in that the application of said peripheral edge area to a target support member and the sealing of the front plate to the sealing or connecting end (22) of the cylindrical body are performed simultaneously, the front plate forming or forming part of the target. the support member.