US2689779A

US2689779A - Alignment-lighthouse for color-screens, etc.

Info

Publication number: US2689779A
Application number: US368198A
Authority: US
Inventors: Albert C Grimm; Milton J Grimes
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1953-07-15
Filing date: 1953-07-15
Publication date: 1954-09-21
Anticipated expiration: 1971-09-21

Description

p 21, 1954 A. c. GRIMM ETAL 2,689,779

ALIGNMENT-LIGHTHOUSE FOR COLOR-SCREENS, ETC

Filed July 15, 1953 3 Sheets-Sheet l 13 1 5 I: 7

INVENTORS 51.22121- E. ERIMM MILTON J. Esme:

ll TI'ORNE Y Sept. 21, 1954 A. c. GRIMM ETAL ALIGNMENT-LIGHTHOUSE FOR COLOR-SCREENS, ETC Filed July 15, 1953 3 SheetsSheet 2 INVENTORS fiLBEn'r E, EmMM & MILTUNJ. EIBIMES J 77012 NE T p 21, 1954 A. c. GRIMM ETAL 2,689,779

ALIGNMENT-LIGHTHOUSE FOR COLOR-SCREENS, ETC

Filed July 15, 1953 3 Sheets-Sheet 5 27 INVENTORJ HLBEHT E. ERIMM it MILTIJN J. EHIMES RTFM d TIOR NE Y Patented Sept. 21, 1954 UNITED STATS OFFICE ALIGNMENT-LIGHTHOUSE FOR CULOR- S GREEN S, ETC.

Albert C. Grimm,

Lancaster,

and Milton J.

Grimes, Ephrata, Pa, assignors to Radio Corporation of America, a corporation of Delaware 6 Claims.

This invention relates to apparatus for use in the inspection and alignment of television colorscreen units of the adjustable-screen variety such, for example, as the ones described and claimed by the same inventors in copending application Serial No. 318,984, filed November 6, 1952.

The principal object of the present invention is to facilitate the rapid and accurate adjustment of color-screen units of the general character described and thus to facilitate the mass-production of color-kinescopes and analogous (e. g., camera and stereoscopic) cathode-ray tubes.

The foregoing and related objects are achieved in accordance with the invention by the provision of an alignment lighthouse comprising a pedestal or table upon which the screen-unit is supported in a position whereat the adjustingmechanism of the screen-unit is engaged by a plurality of tools for selectively applying to said mechanism independent forces capable of moving the screen-plate in any of three coordinate directions as may be required to bring the subelemental ray-sensitive color-areas thereon into register with the pattern of apertures in the foraminous electrode or mask with which said screen is to be used.

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

Fig. 1 is a sectional view taken on the line l--i of Fig. 3 of an adjustable color-screen unit of the type claimed in application Serial No. 318E8 1; the drawing being marked with lines indicative of different adjustments in its mask-to-screen spac- Fig. 2 is an elevational view, partly in section, of an alignment lighthouse constructed in accordance with the principle of the invention and showing theadjustable screen-unit of Fig. 1 setup thereon in position for adjustment;

Fig. 3 is a plan view of the lighthouse of Fig. 2; and

Fig. 4 is a vertical section taken on the line 4 4 of Fig. 3 showing one (of the three) duplicate tools for actuating the adjusting mechanism of the screen-unit.

The Grimm and Grimes screen-unit shown in Fig. 1 comprises a circular frame I consisting of two metal rings la and lb of L-shaped crosssection. The rings la and lb are arranged backto-back and are welded or otherwise connected so that they exert a substantially isotropic clamping force upon the periphery of a tautly stretched foraminous electrode or mask 15. In the kinescope or other cathode-ray tube (not shown) in which the screen-unit is to be usedthe beamelectrons normally pass through the apertures in the mask l5, along different angularly related paths, in their transit to the sub-elemental phosphor covered areas indicated at B, which makeup the mosaic (or Paget) pattern on the target surface kit of a glass screen-plate 5.

The screen-plate 5 is adjustably supported on the frame I by a contrivance which includesthree (see Fig. 3) individually adjustable rodlike supports 1 disposed 120 apart about the periphery of the screen-plate 5. The three places at which the screen-plate 5 is supported are defined by three radially extending V-shaped grooves 512 in the target surface thereof. Each V-groove comprises a self-leveling support for an eccentrically disposed hemispherical terminal it on the end of each of the adjustable rods 1.

Each of the three rods 1 is mounted to permit of independent axial and rotatable movements in the bore of a split stud or collet 9 which is welded onto the lower section lb of the supporting frame I. The collet 9 has a conical outer surface (see Fig. 4) which is threaded to receive the threaded inner surface of a complementary nut i I. Screwing the nut [I up on the split body of the collet 9 causes the latter to exert a clamping force on the rod 1 and thus to maintain it in any selected position. The other or free end of each rod 1 terminates in kerf 5k (or in a flat) which when turned by a screwdriver (as later described) urges the eccentric head it on the upper end of the rod against a side wall of its grooved seat 51; and moves the screen-plate 5 in whatever plane has been fixed by the axial adjustment of the rods 1. Hold-down brackets or springs l3,'which may be supported either by the rods I or on the frame I, serve to maintain the grooved screen-plate 5 on its supporting rods 7.

As explained in greater detail in the earlier filed Grimm and Grimes application, where massproduction is involved it is ver seldom that the foraminous electrode or mask [5 in any two screen-units will be subjected to isotropic tensioning forces of exactly the same intensity. Thus, referring still to Fig. 1, if the mask i5 is subjected to an isotropic tensioning force of an intensity such that the dot-like apertures therein are at the locations indicated by reference characters a, the color-dots B on the target 5t can be brought into register with said apertures only if the screenplate 5 is moved into a plane or position indicated by the line A. Similarly, if the isotropic tensioning force applied to the apertured mask 15 is of an intensity such that its apertures are at locations indicated by reference characters a, the color dots B can be brought into register with the locations a only if the screen-plate is moved into the plane or position indicated by the line A.

As previously brought out, and as indicated in Fig. l by the straight and curved arrows adjacent to the screen-supporting rods I, the adjusting mechanism of the screen-unit is capable of moving the screen-plate 5 toward and away from its apertured mask [5 and can also move said plate about, and tilt it with respect to, an axis normal to the plane of said mask. The alignment-lighthouse of the present invention is designed to apply any or all of the adjusting and locking forces required to align the color-areas B on the screenplate 5 with respect to the pattern of apertures in the foraminous electrode or mask i5.

As shown in Figs. 2, 3 and 4 the alignmentlighthouse of the present invention comprises a pedestal or table H having a removable top or upper base it! containing a large central opening Hid therein to permit the projection therethrough of light-rays from a point 2! beneath the table. Three up-standing posts 23 spaced 120 apart about the opening 190. serve to hold the screenunit in a level position whereat its apertured mask l5 and its translucent screen-plate 5 are illuminated by the light-rays. The plane of the apertured mask I5 is the reference plane of the lighthouse. To ensure that this plane is the same for all screen-units, each of the three rigid supporting posts 23 terminates in a locating pin 23a which passes through a hole in the lower ring lb of the mask-supporting frame I. The shoulder of this pin 23a seats exactly in the plane of the mask l5 and its head extends through a smaller hole in the upper ring la of the frame i. When, as in the instant case, the screen-unit is to be aligned for use in a color-kinescope the distance between the light-source 2| and the plane of the apcrtured mask l5 should, ordinarily, correspond to the spacing between said mask and the planeof-defiection (or virtual source of electrons) in the kinescope in which the screen imit is to be used.

Referring now to Figs. 2, 3 and 4: Three multipurpose tools, indicated generally by reference numeral 25, which are fixed, as by dowels 2?, 120 apart on the table-top i9 supply all necessary adjusting forces for the screen-adjusting mechanism of the screen-unit. Stated generally, these fixtures 25, which are of duplicate construction, comprise: (i) a wrench for actuating the nut H on the collet ii of the adjusting rod 1 (ii) a jack for applying a lifting force to said rod thereby to alter the spacing between the screen plate 5 and its mask :5 and (iii) a screwdriver for turning the rod 1 and hence the screen-plate 5 in whatever plane has been set by the jack.

As brought out in the following description of Fig. 4, the wrench, the jack and the screwdriver in each fixture 25 are arranged about a common vertical axis in a position to engage the appropriate parts of the screen-adjusting mechanism when the screen-unit is seated upon the supporting posts 23 for said unit.

The wrench in each of the fixtures 25 is preferably of the ratchet variety. As shown in Fig. 4 it comprises a vertically arranged hollow metal cylinder or tube 29 through which certain elements of the jack and screwdriver extend. This tube 29 terminates at its upper end in a noncircular opening 3| for receiving the collet nut H on the adjusting rod 1 of the screen-unit. A hollow handle 33 containing a ratchet mechanism, indicated generally at 35, is aifixed to the outer surface of the tube 29 as by a set-screw 3?. The lower end of the tube or cylinder 29 of the Wrench terminates in a flange 39 which has a bearing fit on an upper part 4 l a of the immovable base 4! of the fixture 25 so that the wrench may be turned without disturbing the setting of the other two tools in the fixture.

The jack portion of the fixture 25 comprises a vertical rod-like plunger 43 which bears at its upper end 53a against the adjusting rod l" of the screen-unit. The plunger 43 has a tapered lower end 431) which is biased, by a spring 45, to bear against a cone tile on the inner end of an horizontally extending screw 4"! in the base ii of the fixture. The screw 4? terminates at its outer end in a knurled knob 49 which, when turned clockwise exerts a lifting force upon the plunger 53, through the cone 41c, and thus lifts the rod l and raises the screen-plate 5 with respect to its apertured mask [5.

The screwdriver portion of the fixture 25 shown in Fig. 4 comprises a hollow shank 5| which surrounds the plunger 43 of the jack and extends through the cylindrical body 23 of the wrench. A male blade 53 (or female slot) on the upper end of the shank 51 engages the kerf "wk on the lower end of the rod 7 upon which the screenplate 5 is supported. A knurled knob 55 on the lower end of the shank 5! serves to turn it about its vertical axis. As previously set forth the turnr ing force is converted by the ball-and-groove contrivance at the upper end of the adjusting red I of the screen-unit into a force capable of turning the screen-plate 5 (with respect to its apertured mask 15) either clockwise or counterclockwise in whatever plane said plate has been placed by the lifting force applied thereto through the plunger 43 of the jack.

The present invention is not especially concerned with the technique employed by the operator in determining the direction or directions of movement required to bring the mosaic pattern of the dots (or lines) on the screen-plate 5 into register with the array of apertures in the foraminous electrode or mask i5. Three such techniques or methods are described by Grimm and Grimes in their earlier filed disclosure. Accordingly, it is sufiicient here to state that the light-rays emanating from the point 2i ma be derived from an ultra-violet lamp if the phosphor-dots (or lines) on the screen-plate 5 are to glow in their natural color or colors, as is required when the so-called color-dilution inspection method is employed, and that monochromatic light (e. from. a sodium vapor bulb) should, preferably, be used when the direct observation method or the interference-ring method is used.

What is claimed is:

1. Apparatus for aligning the mosaic pattern on a screen-plate with the apertures of a foraminous element in a television screen-unit of the kind containing a plurality of adjustable sup ports capable of adjusting the position of said screen-plate with respect to said ioraminous element, said apparatus comprising a base having an opening therein to permit the passage therethrough of light rays emanating from a point behind said opening, means disposed on said base about said opening for holding said screenunit in a position whereat its foraminous element is caused to lie in a reference plane spaced a predetermined distance from said point and its screen-plate is illuminated by the pattern of light with which said light-rays are endowed by the presence of said foraminous element in their path, and means disposed on said base about said opening in a position to engage said adjustable screen-supports for selectively applying thereto independent forces capable of altering the sp ing of said screen-plate with respect to said reference plane and the orientation of said screenplate with respect to said pattern of light.

Apparatus in accordance with claim 1 and wherein said last mentioned means comprises a jack for altering the spacing of said screen-plate with respect to said reference plane and a turning-tool for changing the orientation of said screen-plate with respect to said pattern of light.

3. The invention as set forth in claim 2 and wherein said turning tool comprises a hollow shank and said jack comprises a plunger concentrically disposed within said hollow shank.

4. Apparatus for aligning the mosaic pattern on a screen-plate with the apertures of a foraminous element in a television screen-unit of the kind containing a plurality of adjustable supports capable of moving said screen in any of three coordinate directions with respect to said foraminous element; said apparatus comprising a base having an opening therein to permit the passage therethrough of light-rays projected from a point behind said opening, means disposed on said base about said opening for holding said screen-unit in a position whereat its foraminous element is caused to the lie-in a reference plane spaced a predetermined distance from said point and its screen-plate is illuminated by the pattern of light with which said light-rays are endowed by the presence of said foraminous element in their path, and means disposed on said base about said opening in a position to engage said adjustable screen-supports for selectively applying thereto independent adjusting forces capable of moving said screenplate in any of said three coordinate directions as may be required to bring its mosaic pattern into register with said pattern of light.

5. The invention as set forth in claim 4 and wherein said last mentioned means comprises a jack for altering the spacing between said screenplate and said foraminous electrode, a tool for turning said screen-plate about an axis normal thereto, and a wrench for applying a locking force to said adjustable screen-plate supports.

6. The invention as set forth in claim 5 and wherein said jack, said turning-tool and said wrench are disposed about a common axis substantially normal to said reference plane.

No references cited.