US2795718A

US2795718A - Color kinescopes

Info

Publication number: US2795718A
Application number: US450733A
Authority: US
Inventors: Frans Van Hekken; Morris R Weingarten
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1954-08-18
Filing date: 1954-08-18
Publication date: 1957-06-11
Anticipated expiration: 1974-06-11
Also published as: GB811936A; DE964064C; FR1129827A; BE540599A

Description

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June 11, 1957 F. VAN HEKKEN ETAL 2,795,718

COLORA KINEscoP'Es Filed Aug. 18, 1954 2 sheets-sheet 1 if /f if' 1' i if g' f ifa June 11, 1957 F. VAN HEKKEN ErAL 2,795,718

COLOR KINESCOPES Filed Aug. 18, 1954 2 Sheets-Sheet 2 1NVENTOR5 ijnited States Patent coLoR KnsnscorEs Application August 18, 1954, Serial No. 450,733

13 Claims. (Cl. 313-85) Lancaster, Corporation of America, a cor- This invention relates to improvements in color-kinescopes and other (e. g. camera, radar, and stereoscopic) cathode-ray (CR) tubes of the kind containing an apertured mask through which beam-electrons pass in their transit to the electron-sensitive mosaic target-surface of a nearby screen.

In cathode-ray tubes of the various kinds to which the invention-is applicable, the accuracy with which the beamelectrons strike the individual screen-areas depends, in large measure, upon the accuracy with which the maskapertures are aligned with said screen-areas. Thus, in the case of a color-kinescope, should the mask expand by reason of thermal effects occasioned by the impact thereon of the electron-beam, or beams, then the beam-elec- Fig. 4 is an elevational View of one of the links or hinges of the temperature compensated mask;

Fig. 5 is a fragmentary View, partly in section, of the mask and its supports;

, Fig. 6 is a fragmentary View, partly in section, showing an alternative form of mask-supporting hinge r lever;

Fig. 7 is a plan view and Fig. 8 an elevational view of l a mask having a hinged temperature-compensating border, .and

Figs. `9 and 10 are fragmentary sectional views of other forms of hinged mask-boarders, within the invention.

ln Fig. 1 the invention is shown as applied to a 3-gun tri-color kinescope of the so-called masked-target dotscreen variety wherein the red (R) blue (B) and green (G) phosphor dots (see Fig. 2) are arranged in a hexagonal mosaic pattern on the rear or target surface 1 of a glass screen-plate 3. This electron-sensitive color-screen may be of any desired shape e. g. circular or rectangular) and curvature (e. g. spherical, cylindrical or at). In the instant case it is in the form of a circular section of a spherical shell and comprises the front end or window of a metal envelope of more or less conventional form and dimensions. Alternatively, the color screen may trons, or some of them, may impinge upon color-areas"- Y vention is to provide an improved method of and means for maintaining the apertures of a shadow-mask in alignment with the lelemental areas of a mosaic Vtype screen over a wide range of operating temperatures and this too without resort to the use of auxiliary mask-supporting carriages and bearings or costly (low expansion) materials for the mask and/or its supports.

Stated generally, the foregoing and related objects are achieved in accordance with the present invention by the provision of a mask having a marginal edge portion or portions comprising a movable link, hinge orlever (frequently hereinafter referred to as a hinge) which, when actuated by the force of expansion (or contraction) of the mask material, moves the apertured scanned-area of the mask towards (or away from) the screen along lines which coincide, substantially, with the deflection angle of the beam, or beams, at each aperture. (The term detlection angle, as applied to a S-beam tube, is the angle subtended by a line drawn from any point on the screen, or its mask, along a median line of the beam-paths to the central axis of the tube.) The expansion or temperature compensating hinge may be integral with the mask, and this structure carried byaframe which in turn may be removably supported on fixtures or protuberances provided for the ptupose on the inner surface of the cap or other part of the envelope.

The invention is described in greater detail in connection with the accompanyingv two sheets of drawings, wherein:

Fig. lis a longitudinal sectional view of a 3-gun tricolor kinescope of the shadow-mask dot-screen varietyr containing a temperature compensated mask constructed in accordance with the principle of the invention;V

Fig. 2 is a fragmentary rear-elevational view of the screen-unit of. the color-kinescope ofy Fig. 1, showing a conventional (hexagonal) pattern of mask-apertures and color-phosphor dots;

Fig. 3`is a front elevational view of the mask of the screen-unit of Figs. 1 and 2, showing a six-point distribution of the mask-supports;

comprise a at glass plate, not shown, mounted behind the window.

`The mask 7 for the mosaic screen may be formed of any suitable material having a positive temperature coeicient of expansion. Thus it may comprise a thinmetal (e. g. iron, steel or copper) member, or it may be made of perforated glass which has been metallized or otherwise treated to render its surface conducting.

Where, as in Fig. 1, the mosaic screen pattern (RBG)l is laid down directly on the concave inner surface 1 v of the face plate 3, the mask 7 is appropriately curved so that it conform generally with said concave targetsurface. mask are arranged in the same (e. g. hexagonal) systematic pattern-as` the phoshor triads RBG on the mosaic screenl, there being one mask-aperture for each triad. Ags-is conventional, the red, blue and green electron-guns `9r, 9b, 9 g are arranged delta-fashion about the central axisr'x-x lof the envelope, in the glass neck 11. With the guns and mask-apertures thus arranged the three scanning beams pass through-the tubes plane-ofdeection A-A with their kcenters equally spaced from each other at a common distance-from the tube axis and converge adjacent. to the surface of the mask Where their paths cross and proceed to the respective color areas on the screen. l

The plane-of-deflection, referred to in the precedingl paragraph is here defined as the plane in which the axis of each deflected beam, when extended rearwardly, intersects'` the axis of origin of that beam. When the three beams are undeflected, i. e. when they are directed to the center of the screen-unit, the plane-of-deflection crosses the central axis x-x of the tube at'or near the center of the deflection yoke 13, as indicated by' the lineA-A.

mask 7 is supported at a number (in this case, six) of places about its periphery by hinge elements 15 (see Fig. 4) which are secured, as by welding, at one end to theimask andat the opposite end to a rigid metal annulus or'frame 17. The frame 17 and hence the mask 7 and its hinges 15` are in turn supported upon metal pins 19 A which extend inwardly from the inner surface of the metal sidewalls 4of the cap 21` of the tube and are seated in V-.grooves 23 in smallmetal blocks Z5 on the outer surface ofthe masks frame 17.

ln one successful embodiment of the invention, wherein six hinges 15 provided the requisite temperature-com- Peiftented June 1,1, 1 957A The apertures 7a in the scanned area 7s of the pensating hinging movements for a rectangular maskhaving a 2l" diagonal, the hinge members 15 were of duplicate construction and were formed of thin (0.006" Inportion 15b secured adjacent to its outer edge 15e (by similar welds, not shown) to the edge of themask 7. The hinging action of these metal supports 15 was confined to the area of the bends 15d and 15e in the metal by vnarrow slits 15j, 15g, respectively, along each bend and by reinforcing'embossments 15h between said slits.

It will be observed upon inspection of Fig. l that the surface or plane 15b of the link portion of the masksupporting hinge 15 forms an angle of 90 with respect to a line y-y drawn from `its upper bend 15a' t0 the mid-point of the tubes plane-of-dellection A-A. That is to say, when the mask is cold, the inclined surface 15b is normal to a line v-y extending therefrom to the centerof-dellection of the beam (or beams) at that point. With the hinge or link members 15 thus arranged, their hinging action (when subjected to the force of expansion of the heated mask material) is such that each apertured area in the mask moves toward the screen along a substantially straight path which coincides with a line drawn from the center of detiection to the phosphor triad associated with that particular aperture. Thus the alignment between the mask apertures 7a and the elemental areas (RB and G) on the target surface of the mosaic screen is maintained substantially irrespective of the operating temperature of the mask.

it is apparent that the invention is not Ilimited in its useful application to the particular form or kind of hinge in the mask is supported for slidable movement on one arm'27a and the force P (of expansion of the mask material) is applied to the other arm 2711, thefulcrum F being at the apex of the angle formed by the two arms.

Instead of making the temperature compensating hinges inthe form of separate pieces and welding them in place they may be formed integral with the mask, as shown, by Way of example, in Figs. 7 to 10 inclusive.

In Figs. 7 and 8, the centrally located apertured targetportion of the mask, which is here designated 39, is in the form of a rectangular (instead of circular) portion of a spherical shell and is provided with Van integral temperature compensating border or inner-rim portion 33 made up of a multiplicity of circumferentially spaced, rigid, link elements 35 which have inclined surfaces 37 connecting the apertured target area 39 of the mask with its upstanding mask-supporting outer-rim portion 41. Here, as before, the inclined surfaces 37 of the link portions 35 of the mask-supporting hinge preferably form angles of 90 with respect to lines y-y drawn from their centers to the mid-point of the tubes plane-of-deection (A-A, Fig. l). Also, as before described, the hinging action is conned to the area of the

flexible bends

43 and 45 in the metal at the opposite ends of each of the 'rigid link elements 35. 1

In reducing the above described embodiment of the invention to practice the apertured part 39 of the mask 31 and its open-work border 33 were formed in a single at sheet of thin-metal by a conventional etching process and the sheet then deepdrawn into its ultimate shape with the aid of a die, not shown.

In the embodiments of the inventonabove described in connection with Figs. 7 and 8 the required rigidity of the link elements 35 was achieved by making the body of each link wider than its terminal portions. The same v result has been achieved by making the links of uniform 4 width, as shown at 51 in Fig. 9, and reinforcing them, each by an embossment 53.

In all of the embodiments of the invention thus far described the hinges or links between the target area of the mask and its supporting rim are separated one from the others by intervening spaces. While this is desirable (because of the resulting saving in weight), it may add to the cost of the unit and, in any event, is not always essential to the practice of the invention. Thus, as shown in Fig. l0, the rigid elements of the hinge may comprise embossments 55 pressed in an imperforate border 57 surrounding the target areas of the mask, which is here designated 59.

As previously indicated, the embossments 15h (Fig. 4), 53 (Fig. 9), 55 (Fig. l0) serve to reinforce the innerrim portion of the hinge and thus to confine its pivotal movements to the area of the exible bends (15d, 15e, Fig. 4;

V

43, 45, Figs. 7-10) in the metal. Reinforcement or stitfening of the inner-rim or body of the hinge may also be achieved by thickening the metal (e. g. by electroforrning) of which said part or parts are formed, or in other ways. For example by the use of discrete metal bars or ribs, not shown. Where stiifening ernbossments are employed, the embossrnents may assume various forms. That is to say, they are not necessarily of the crossed pattern shown at 15h, Fig. 4, or of the parallel-line pattern shown at S3, Fig. 9; 55 Fig. l0, but may comprise mere dot-'like embossments, not shown.

From the foregoing specification it should now be apparent that the pivotal mask-supporting means of the present invention provides a simple yet effective means for maintaining the apertures of a shadow-mask in alignment with the elemental areas of a mosaic screen over a wide range of operating temperatures.

What is claimed is: Y

l. A cathode-ray tube comprising an evacuated envelope having a longitudinal axis and containing means for generating at least one electron-beam, a mask extending across said axis in a position to be scanned by said beam, said mask being constituted essentially of a material that expands when subjected to heat generated as an incident to the impact of beam-electrons thereon and containing a multiplicity of apertures through which beam-electrons pass along v substantially straight paths which form variousV deflection rangles with said longitudinal axis as determined by the instantaneous position of said beam during its scanning movements, a screen having an electron-sensitive mosaictarget-snrface spaced from said maskvwith the elemental areas of which said mosaic is comprised aligned with respect to the apertures in said mask, and pivotal means cooperatively associated with said mask for supporting said mask Within said envelope and for causing each apertured area of said mask to move along said straight paths in response to the expansion of said mask material when it is subjected to heat generated as an incident to the impact of beam electrons thereon.

2. The invention as set forth in claim l and wherein said last mentioned means comprises hinge means tlexibly connected at one end to the edge of said mask and ilexibly connected at its opposite end to a support on the interior of said envelope.

3. The invention as set forth in claim 2 wherein said link member is disposed along an axis that formsan angle of approximately 90 with respect to a straight line drawn from said one end of said link to the point whereat said straight beam-paths intercept the longitudinal axis of said tube.

4. A mask comprising a substantially rigid marginal edge-portion for attachment to a support, a centrally located apertured target-portion constituted essentially of a temperature-sensitive material, and binge means responsive to expansion and contraction of said temperature-sensitive material `connecting said apertured targetportion to said marginal-edge portion.

5. The invention as set forth in claim 4 and wherein said hinge means comprises a substantially rigid link member iiexibly connected at its inner and outer extremities to said target and marginal-edge portions, respectively.

6. A mask comprising a centrally located apertured target-portion substantially in the form of a section of a spherical shell and constituted essentially of a material that expands when subjected to heat generated by electron-bombardment, an inner-rim portion connected to said spherical target portion by a exible bend in said material and inclined inwardly with respect to the concave surface of said spherical shell, and an outer-rim portion connected by a second tiexible bend in said material to the outer edge of said inner-rim, whereby said inner-rim comprises the connecting link and said first and second bends comprise the pivots of a hinge capable of translating the force of expansion of said spherical target portion into a movement in a direction away from its center-of-curvature.

7. The invention as set forth in claim 6 and wherein said mask consists essentially of a single piece of thin metal and said inner-rim portion of said thin metal contains a plurality of spaced-apart strengthening embossments disposed between said tirst and second exible bends in the metal, whereby the pivotal movements of said hinge are conned substantially to said flexible bends.

8. The invention as set forth in claim 7 and wherein said inner-rim portion of said mask contains perforations in the metal between adjacent ones of said strengthening embossments.

9. A mask comprising a centrally located apertured target portion constituted essentially of a material that expands when subjected to heat, an inner rim portion and an outer-rim portion, rst exible means responsive to expansion of said material disposed between said target portion and said inner-rim portion, and second flexible means disposed between said inner-rim portion and said outer-rim portions.

10. The invention as set forth in claim 9 and wherein the inner-rim portion of said mask is constituted of the same material of which said target portion is comprised and said first and second flexible connecting means comprise discrete flexible areas in said material.

11. A mask constituted essentially of thin metal and comprising an outer-rim portion for attachment to a support, an inner-rim portion connected to said outerrim by a bend in said thin-metal and a central apertured target portion connected to said inner-rim by a second bend in the thin-metal.

12. A mask constituted essentially of thin metal and comprising a circular outer-rim portion for attachment to a support, a frusto-conical inner-rim portion connected to said outer-rim by a bend in said thin-metal and a central traget-portion in the form of a circular section of a spherical shell containing a multiplicity of systematically arranged apertures and connected to said innerrim by a second bend in said thin-metal.

13. A mask constituted essentially of thin metal and comprising a rectangular outer-rim portion for attachment to a support, a frusto-pyramidal inner-rim portion connected to said rectangular outer-rim on each of its sides by a bend in said thin metal, and a central electrontarget portion in the form of a rectangular section of a curved surface containing a multiplicity of systematically arranged apertures and connected to said inner-rim on each of its sides by a second bend in said thin-metal.

References Cited in the le of this patent UNITED STATES PATENTS Re. 23,735 Olson Nov. 10, 1953 2,546,828 Levy Mar. 27, 1951 2,611,100 Faulkner et al. Sept. 16, 1952 2,682,620 Sanford June 29, 1954