US2998033A - Apparatus for producing cathode ray tubes - Google Patents

Description

1931 A. SAN DOR 2,998,033

- APPARATUS FOR PRODUCING CATHODE RAY TUBES Filed Feb. 12, 1957 INVENTOR AUREL/l/J SANDOR ATTORN 2,998,033 APPARATUS FOR PRODUCING CATHODE RAY TUBES Aurelius Sandor, Forest Hills, N.Y., assignor, by mesne assignments, to Sylvania Electric Products Inc., Wilmington, Del., a corporation of Delaware Filed Feb. 12, 1957, Ser. No. 639,770 3 Claims. (Cl. 140-715) My invention is directed toward cathode ray tubes for use in color television systems.

In present color television systems, the visual image is formed upon a cathode ray tube screen provided with a plurality of screen areas separate from each other and covered with a thin electrically conductive coating. Selected groups of these areas are coated with different phosphor materials so as to produce different colored images. The electron beam generated within the tube is deflected upon each area in turn, thus producing, in well known manner, different colored images in such rapid succession that they appear visually to mix and crate a composite colored image. Normally, three primary colors are used in these systems.

One type of tube employed in this manner is provided with a fiat image or screen mounted within the evacuated tube envelope. The coated screen areas are in the form of extremely narrow horizontal or vertical strips which are substantially parallel. The first, fifth, ninth (1+4N) strips produce one of the primary colors, for example, red. (N can be any positive integer or zero.) The second, fourth, sixth (2N) strips will produce another color, for example, green. The third, seventh, eleventh (3+4N) strips will produce the third color, for example, blue. A single electron gun produces an electron beam, which, when in its center or Zero deflection position, is perpendicular to the image plate.

Interposed between the gun and the coated portion of the image plate is a wire grid containing a plurality of parallel wires which are contained in a plane parallel to that of the image plate. These wires extend along the long dimension of the strips, one wire being associated with each blue or red strip. The wires associated with the red strips are connected together to a first common terminal. Similarly, the wires associated with the blue strips are connected together to a second common terminal. The conductive coating on the screen or image plate is connected to a third terminal.

When the first and second terminals are maintained at the same potential, and the third terminal is maintained at a much higher potential, the potential difierence acts to accelerate and focus the electron beam; the electron beam will be directed upon the green strips only, and a green raster is produced. If now the potential difference between the first and second terminals is adjusted switching circuits coupled to the first and second terminals supply these potentials as required.

This type of tube has been described in the literature. For example, further details on this tube will be found in Proceedings of the I.R.E., July 1953, pp. 851-858.

At present such tubes are produced with great difiicu-lty and at substantial cost. For example, in producing the tube, it is first necessary to secure the wire grid to the screen to form a grid-screen assembly. The first 'half of the grid system is wound in one direction. Conventionally, this assembly is produced by first winding the wires associated with the red strips upon the screen atent Q F ice and then winding the wires associated with the blue strips upon the screen. The first winding operation is carried out by machine, the wires always being wound in the same direction. The second winding operation is manually performed by skilled technicians, the wire being wound in a reverse direction. Further, the wire alignment both with respect to the two sets of wires and tothe phosphor strips must also be carried out laboriously by these technicians.

Accordingly, it is an object of the present invention to eliminate all manual wire winding operations conventionally required in the production of grid screen assemblies of the character indicated.

Another object is to provide new and improved apparatus for producing grid-screen assemblies of the character indicated more rapidly and less expensively than heretofore known.

Still another object is to improve apparatus for producing grid-screen assemblies of the character indicated in such manner as to greatly simplify alignment and wire winding operations.

These and other objects of my invention will either be explained or will become apparent hereinafter.

In accordance with the principles of my invention 1 provide a rotatable mandrel having a substantially uniform cross section, the mandrel periphery having a polygonal shape, whereby the surface of said mandrel is composed of a plurality of faces. At least one (and preferably more) of said faces each contains a removable phosphor screen, each screen being provided with a plurality of first, second and third types of aligned narrow phosphor strips of substantially equal width. Each strip extends in a direction perpendicular to the axis of the mandrel, the (1+4N) strip being of the first type, the (2N) strip of a second type, the (3+4N) strip of the third type, wherein N attains any positive integral value including zero.

Each mandrel face is provided with first and second parallel edges which are parallel to the mandrel axis, the edges of each screen containing face extending above the exposed surface of the corresponding screen. All of these edges are provided with substantially aligned wire receiving grooves, corresponding grooves of the said two edges of each screen containing face being aligned with a corresponding phosphor strip of one of the first and third types.

As the mandrel is rotated, wire fed by suitable means, as for example a drum, is wound about the mandrel in such manner that the wire is placed in the grooves of all of the edges, whereby any wire section extending between corresponding grooves of the two edges of each screen containing face is in registration with its corresponding phosphor strip.

Means positioned adjacent the first and second edges of each screen containing face sever all even-numbered wire sections adjacent the first edge and also sever all odd-numbered wire sections adjacent the second edge. First and second electrically conductive members which extend in a direction parallel to the mandrel axis are secured to each screen adjacent corresponding first and second edges. The even-numbered wire sections are electrically and mechanically connected to the first conductive member, while the odd-numbered wire sections are electrically and mechanically secured to the second conductive member. At this point, one or more grid screen assemblies have been completed and can be removed from the mandrel for subsequent placement in a grid-focusing color tube.

My invention will now be described in detail with reference to the accompanying drawing wherein:

FIGS. 1 and 2 are respective top and side views in an apparatus in accordance with the invention; and

FIG. 3 shows the completed grid-screen assembly.

Referring now to FIGS. 1 and 2, there is shown a polygonally shaped mandrel 12 having a substantially uniform cross section. In this example, the polygonal shape is a rectangle defined by edges 38, 40, 42 and 44 which are parallel to the mandrel axis 32, thus defining four faces on the surface of the mandrel, each surface being included between adjacent two edges 3840, 4042, 4244- and 3844. The two opposite faces including the longest dimension of the rectangle, i.e.

those faces included between edges 4038 and 4244,

each contain a removable phosphor screen 20; the phosphor screen is of the known type previously described, being formed from glass with a phosphor coating composed of a plurality of first, second and third types of long narrow phosphor strips of substantially equal width, which extend in a direction perpendicular to the axis 32 of the mandrel. An aluminized coating is applied over the phosphor strips.

First and second electrically non-conductive members, as for example square shaped glas rods 18, which extend in a direction parallel to the mandrel axis are cemented to the screen in positions adjacent the corresponding edges. interposed between each electrically nonconductive member 18 and the correspondingedge is a parallel electrically conductive member 16 formed, for example, of metal. Each of the edges is milled on top to produce wedge shaped wire containing grooves.

A molybdenum, stainless steel, or other appropriate metal Wire 22, approximately 2.5 thousandths of an inch in diameter, is fed from a drum or other conventional device (not shown) to the mandrel, the starting end of the wire being fastened by screw 36 to edge 40. The mandrel is then rotated about its axis 32 and the wire is wound in the grooves of all of the edges, being progressively moved along the mandrel axis as the mandrel rotates. When the winding operation is completed, the free end of the Wire is attached to the appropriate comb or edge 36.

The grooves in the various edges or combs are so arranged that any section of the wire extending between corresponding grooves in the two edges of each screen strip with ultraviolet.)

Each wire section is then attached at both ends to the non-conductive member .18 through the use of non-conductive or insulating cement. Two stretching combs 24 are then manually pushed outwards from suitable recesses in the mandrel 12. .Each comb has a plurality of wire engaging grooves 26 which coincide with alternate wire sections. The sets of grooves on both combs are shifted permanently one pitch width relative to each other; -i.e. one of the combs has its grooves aligned with the evennumbered wire sections, while the other comb has its grooves in registration with the odd-numbered wire sections. As these combs are pushed further outwards, the level of the one set of wires engaged by the comb grooves of any one comb are stretched outward and are thus separated from the other set of wires which is not stretched.

Since the groovesof one comb are offset by one pitch width, both sets of wires are stretched at one end and are unstretched at the other end, the stretched end of oneset being opposite from the stretched end of the other set. Adjacent each edge 38, 40, 42 and 44, the

ie all wires are maintained at the same potential.

stretched wires are cut apart, and the ends so severed are bent back and forth at members 18 until the wires break at this member.

The remaining wires which extend between each member 18 and its corresponding member 16 affixed to the opposite side of screen 21 are then cemented to this member 16 with an electrically conductive cement. In this manner, one set of wires, as for example the even-numbered wire sections, are electrically connected together to one member 16 associated with a phosphor screen, while the other set of Wires, the odd-numbered wire sections, are electrically connected to the other member 16 associated with this phosphor screen.

The resultant grid-screen structure has then been completed and can be removed from the mandrel, as shown in FIG. 3.

Since the structure itself is conventional, the details of the screen construction have not been shown in the figures, such details being found, for example, in the I.R.E. article previously cited.

Certain types of grid focusing color tubes make use of three separate electron guns; these types utilize a similar grid-screen structure. However, in this similar structure, the two sets of grid wires are not interleavecll; t will be obvious to those skilled in the art that by eliminating the use of the conductive members 16 and the side combs 24, this structure can be produced by my apparatus.

While I have shown and pointed out my invention as applied above, it will be apparent to those skilled in the art that many modifications can be made within the scope and sphere of my invention as defined in the claims which follow.

What is claimed is:

.1. In the method of manufacturing a grid-screen assembly for use in a cathode ray tube, the steps comprising mounting a support coated with a phosphor screen in the form of a plurality of long narrow phosphor strips to a face of a rotatable mandrel, said support extending in a direction substantially parallel to the axis of said mandrel and said strips extending in a direction substantially perpendicular to the axis of said mandrel, winding a wire continuously in one direction about said mandrel to produce a grid structure wherein the wires of said grid are spaced from and substantially parallel to said phosphor strips, stretching all odd numbered wires of said grid adjacent one edge of said face insulatingly fastening said stretched odd numbered wires adjacent to said one edge of said support, breaking off said odd numbered wires at said one edge of said face, electrically connecting together the even numbered Wires at said one edge of said face, stretching all even numbered wires of said grid adjacent an opposite edge of said face, insulatingly fastening said stretched even numbered wires to said opposite edge of said support, breaking off said even numbered wires at said support and electrically connecting together the odd numbered wires at said opposite edge of the face of said support.

2. In the method of manufacturing a grid-screen assembly for use in a cathode ray tube, the steps comprising mounting a support coated with a phosphor screen in the form of a plurality of first, second and third types of long narrow phosphor strips to a face of a rotatable mandrel, said support extending in a direction sub stantially parallel to the axis of said mandrel and said strips extending in a direction substantially perpendicular to the axis of said mandrel, winding a wire continuously in one direction about said mandrel to produce a grid structure, wherein odd numbered and even numbered wires of said grid are spaced from, substantially parallel to, and aligned respectively with strips of the first and third types, aligning the wires of said grid with said strips, stretching all odd numbered wires of said grid adjacent one edge of said face insulatingly fastening said stretched odd numbered wires adjacent to said one edge of said support, breaking off said odd numbered wires at said one edge of said support, electrically connecting together the even numbered wires at said one edge of said support, stretching all even numbered wires of said grid adjacent an opposite edge of said face, insulatingly fastening said stretched even numbered wires to said opposite edge of said support, breaking 05: said even numbered wires at said opposite edge of said support and electrically connecting together the odd numbered wires at said opposite edge of the face of said support.

3. Means for manufacturing accurately aligned grids comprising a supporting mandrel having four parallel, grooved, wire supporting edges; a pair of movable combs carried by said mandrel at a pair of opposite sides thereof; one of said combs being mounted on said mandrel so as to selectively engage even numbered wires in the grooves of said mandrels; means for moving said one comb into contact with the even numbered wires wrapped around said mandrel so as to separate said even numbered wires from the odd numbered wires around said mandrel; the second of said combs being mounted 6 on said mandrel so as to selectively engage odd numbered wires in the grooves of said mandrel; and, means for moving said second comb into engagement with the odd numbered wires carried in the grooves of said mandrel so as to separate the odd numbered Wires from the even numbered wires.

References Cited in the file of this patent UNITED STATES PATENTS 1,478,071 Trimble Dec. 18, 1923 1,934,097 Simon Nov. 7, 1933 2,183,635 Barker Dec. 19, 1939 2,194,551 Holman Mar. 26, 1940 2,610,387 Borland et a1. Sept. 16, 1952 2,683,833 Zaphiropoulos July 13, 1954 2,726,686 Bongers Dec. 13, 1955 2,791,710 Dressler May 7, 1957 2,824,251 Patterson Feb. 18, 1958 2,909,200 Miller et a1. Oct. 20, 1959 FOREIGN PATENTS 1,075,731 France Apr. 14, 1954

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