US2778161A - Method of undulating rods for electrode structures - Google Patents

Description

1957 'R. ZAPHIROPOULOS 2,773,161

METHOD OF UNDULATING RODS FOR ELECT RODE STRUCTURES Filed Sept. 15, 1953 2 Sheets-Sheet l 1957 R. ZAPHIROPOULOS 2,778,161

METHOD OF UNDULATING RODS FOR ELECTRODE STRUCTURES Filed Sept. 15, 1953 2 Sheets-Sheet 2 United States Patent METHOD OF UNDULATING RODS FOR ELECTRODE STRUCTURES Application September 15, 1953, Serial No. 380,205 6 Claims. (Cl. 49-81) The present invention relates to the undulation of elongated rods through the application of force or pressure effective at generally uniformly spaced positions therealong with successive positions of pressure application being from opposite directions. The rods may be of any desired cross-section but for convenience may be considered as generally circular. The appliedpressure is normally of a magnitude insufiicient to deform the rod until it is softened or plasticized, which softening then permits it to assume a generally zigzag configuration, with the distortion being generally proportional to the pressure applied. The distorted shape is preserved while the rod is hardened.

Undulated rods in accordance with the foregoing find application as vibrational damping rods in grid structures employing substantially parallelly arranged tautly strung conductors generally occupying a common plane. One or more undulated rods having insulating characteristics may be interwoven in such grid structures to damp vibrations occasioned by the physical properties of the grid or arising from the effects of electrical stresses established when the grid structure forms an operative component of an electron tube.

The invention has particular application to a multiple strand grid structure for location in proximate relation to a target or screen area of a cathode-ray tube. The application of suitable potential to the grid and target structures relative to the electron beam source of the cathode-ray tube establishes an electric focusing field between the grid structure and target. area. If the cathode-ray tube is to be used for the reproduction of color television, the target or screen area thereof is provided with light producing phosphor coatings of different characteristics arranged thereon in cyclically repeating sequence so that light observable in selected different colors obtains from beam impact on the target. Control .of the electric field enables the angle of incidence of the scanning beam to be altered while the beam is focused to substantially subpunctiform size in at least one dimension at the position of impact upon the target area. 1

The individual strands of the grid structure are tensioned to maintain substantialparalleelism while occupying substantially coplanar relation. The potential applied to the target relative to the electron beam source may be approximately 3 or 4 times that applied to the grid. Then by establishing a difierence of potential approximately equalling ,4; of that normally on the grid, between adjacent strands of the grid, the angle of incidence of the trace is altered and the beam is deflected in the direction of the strands which are most positive relative to the beam source. By making the spacing between adjacent strands substantially equal to the Width of a single color cycle, the beam may be caused to impact the phosphor coated target at any desired position thereby effecting color reproduction.

Often times, as many as 400 to 500 or more strands may comprise a single electrode structure usable to effect color reproduction. The tautly drawn individual,

strands of such an electrode structure have a natural period of vibration, the effects of which adversely modify the functions of the electrode structure as above outlined. Any vibration established among the strands varies the spacing between the normal plane of the electrode structure and the target electrode, thereby causing thediflierence in potential established between the electrode structure and the target to be effective over different spacings which disturbs the beam focus. Likewise, the fact plied thereto different potentials with respect to the electron beam source tends to establish vibration in the multi-strand electrode structure particularly troublesome when it is appreciated that the frequency of changing the respective potentials applied to adjacent strands is high. Y The present invention provides a method of undulating rods which are respectively interleaved among the strands of the grid structure. The undulation permits alinement of the grid conductors in a common plane and serves to maintain thedamp rods in suitable orientation therewith. The damp rods are of a diameter or width sufiiciently small as to preclude the casting of shadows on the viewing or target area of the cathde-ray tube. Also, the damp rods generally possess insulating characteristics since they contact adjacent strands of the electrode structure which in certain applications have different potentials applied theretorelative to the beam source as above mentioned. Vitreous rods having a diameter in the neighborhood of from 3 to 6 mils have been found suitable for use as the damp rods herein described, since they are thermo plastic, inert under electron bombardment, and good insulators. The invention also contemplates the formation of strip-like elongated members, such as, glass ribbon into vibrational damping elements.

The vitreous rods are first interleaved in the grid structure such that adjacent strands exert pressure from opposite directions against the vitreous rods and at spaced positions therealong. The interleaving is conveniently accomplished if a'spreader bar is first placed through the grid such that adjacent strands are displaced oppositely to provide free passage for a vitreous rod which is then inserted along an edge of the spreader bar and normal to the strands of the grid. The spreader bar is then removed to permit the strands of the grid to exert pressure against the viterous rod of a magnitude normally thereof by the grid strands in assuming substantially coplanar relation. Upon cooling the damping rod retains its zigzag shape and the structure is ready for mounting in the viewing end of a cathode-ray tube.

Suitable apparatus for carrying out the method outlined may comprise an open frame adapted to support the grid and clamped rod. Preferably, the open frame includes at least a pair of cross-members adapted to support the grid structure with the rod occupying a position parallel with and substantially midway between the cross-members such that the strands assume substantially coplanar relation where supported. A guideway spanning the open frame is provided for a traveling heater which is adapted for proximate location with a clamped rod. Means are provided for moving the heater along the guideway at a controlled rate so that the rod is softened by heat from the traveling heater and undulated by the strands in returning to a common plane. If more than a single vibrational damping rod is to be employed in an electrode structure as described, the guideway and traveling heater are merely moved along the frame to a position to operate upon a further vibrational damping rod in the manner aforestated. In the alternative, a multithat adjacent strands may have ap-.

- anchoring wire looped filament heater or a plurality of guideways and associated traveling heaters may be-employed simultaneously to effect the undulation of a plurality of clamped vibrational damping rods. However, in the latter event the heaters are staggered so that a single conductor of the electrode structure is not heated in many spots at once, thereby avoiding sagging. In'lieu oi the traveling heater, one or more stationary filaments extending across the open frarne may be utilized for heating the clamped vitreous rods. Such a heating arrangement is shown and described in United States application Serial No. 380,311 entitled Method of and Apparatus for Undulating Rods concurrently filed by the same inventor.

With the foregoing in mind, amongthe objects of the present invention, are the following: The provision of a simple method of undulating rods and the provision of apgaratus-of simple character'for undulating a clamped 1"0 Other and further objects of the present invention will become apparent to those skilled in the'art from a reading of the following detailed description thereof when taken in the light'of the accompanying drawing wherein:

Fig. 1 is an isometric view of apparatus in accordance with the present invention suitable for effecting the undulation of a vitreous rod;

Fig. 2 is a view in elevation of a target and electrode structure with a spreader bar inserted between the electrode-strands to permit the insertion of a vitreous rod to be undulated;

Fig. 3 is an enlarged isometric view of a portion of the assembly of Fig. 2;

Fig. 4 is an enlarged sectional view of a. portion of the structure in accordance with Figs. 1 and 2 and including-a traveling heater in operative relation therewith;

Fig. 5 is an isometric view of a portion of the traveling heater; and

"Fig. 6 is a view partly in section and partly in elevation of the traveling heater and associated guideway structure in operative relation with a rod being undulated.

In Fig. 1 there is shownan open table-like frame 11 having a pair of horizontal supporting bars 13 fixed thereacross. The bars 13 are provided to support a target and electrode structure as illustrated in Fig. 2. The structure is shown in elevation as it would appear when viewed from the electron beam source of a cathode-ray tube. A translucent base 15 has affixetl thereto, near outer edges thereof, a pair of glass spacer bars 17 suitably notched (not shown) to accommodate the conducting strands 19 of the grid which occupy a common plane between the spacer bars. As was mentioned, alternate strands 19 may comprise a set of grid wires with the intermediate strands 19 forming a second set of grid wires.

Fig. 3 shows the grid wire anchoring structure capable of permitting electrically separate sets of conductors to comprise the grid structure of Fig. 2. A rectangular frame 21 is placed against the face of the base 15 opposed to the face adapted to be impacted by the electron scanning beam. A pair of anchoring bars 23 (only one of which is shown in Fig. 3) is affixed respectively to pposite arms of the rectangular frame 21. Each of the anchoring bars 23 is provided with spaced apart hooks Z whichmay comprise bent tabs disposed along an edge of the bar over which a continuous conductor is looped back and forth to provide a first set of parallelly located conducting wires for the grid. A layer of insulation 27 electrically separates a second rectangular frame member 29 from the first set of grid wires. A second pair of bars 31 is secured to opposite arms of the second frame 29 and have books or turned out tabs 33 disposed at spaced intervals respectively between the hooks or tabs 25 to accommodate a second conducting at intervals over the hooks 33 to form the second set of grid wires. The structure of Figs. 2 and 3 permits the application of difierent potentials relative to the beam source to the anchoring bars 23 and 31.

The phosphor target area is located within the dotted all) outline of the frame 21 on the face of the base 15 visible in Fig. 2. Generally the phosphor coatings are covered by a thin aluminum film or other material which is electron permeable and electrically conducting so that a substantially uniform potential surface is available on the face of the base 15. A difierence of potential is established between the grid structure represented by the strands 19 and the aluminum film deployed onthe base 15. As hereinbetore mentioned through the application of suitable potential, the grid strands provide the effect of electron lenses capable of focusing'the scanning beam. on the phosphor coatings. The application oi-ditr'erent potentials to adjacent strands 19' enablesdefiection of the focused beam. However, a diiterence of. potential existing between adjacent strands 19 tends to establish vibration among the strands'which affects the deflecting function. Likewise, changing of the instantaneous potential effective at the grid relative to that of the aluminum film introduces electrical forces of attraction and repulsion which tend to move the strands 19 longitudinally of the cathode-ray tube. Such displacement is undesirable in that beam focus is noticeably affected. Also, vibration is established among the strands 19 due to the physical properties'of theplurality of tautly drawn conductors.

A vitreous rod having a portion thereof undulat ed in theform'of a clamping rod is represented at 37 in Fig; 6. The rod 37 is'shown interleaved between adjacent strands 19 of the grid strnctureof Fig. 4. A fiat spacer bar 39 is first inserted into the grid structure in interleaved fashion with respective strands 19 as is shown in Fig. 2. Adjacent strands are displaced in opposite directions from the normal or common plane of the grid structure 'by the spacer bar. The rod 37 is then passed freely in interleavedfashion through the grid structure adjacent to an edge of the spacer bar 39. The spacer bar 39 is then withdrawn'so that adjacent strands 19 exert pressure from oppositedirections and at spaced intervals along the rod 37. With the rod to be undulated in this position, the assembly of Fig. 2 is placed on the cross bars 13 of the frame 11 such that the rod 37 occupies a position substantially midway between the bars 13 and parallel therewith. As is best represented in the cross-sectional view of Fig. 4, the strands 19 occupy substantially coplanar relation where supported by the bars 13 but are displaced in opposite directions intermediate the bars by the rod 37.

The rod 37-is softened by heat generated by a travelling heater which comprises a ceramic holder 41 adapted to contain .a heating filament or coil 43 (Figs. 5 and 6). Electrical leads 45 comprise supporting legs for the holder 41. The leads pass through a horizontal block or carriage 47 adapted to slide along a slot 49 provided in a box-like support 51 hinged to a cover plate 53. The cover plate 53 is secured to a trolley 55 adapted to move along a cross arm 57 of the openframe 11. A screw 59 is provided to lock the trolley 55 in position along the cross arm 57 by engaging any of a plurality of holes 61 provided therein. A spring catch 63 depends from the trolley 55 for engagement with the groove 65 to lock the box-like support 51 in operative position with the ceramic holder 41 extending through an opening 67 in the cover plate 53. In this mannerthe filament 43'is placed adjacent to the clamped rod 37 as is shown in Figs. 4 and 6.

By means of pulleys 71 (Fig. 6) and 73 (Fig. 1), the latter ofwhich is driven by a motor'75, the block 47 supporting the travelling filament is caused to move along the slot 49 at a constant or controlled rate. The motor 75 is supplied with electrical power through a cord 77 and electrical plug 79. Electrical connection is established to the filament 43 through a pair of inlet leads 81 preferably including an adjustable rheostat 83 between the inlet plug 85 and the heavy leads 45. By adjusting the rheostat 83 the amount of current supplied controlled providing a direct released to drop the travelling heater and box-like support 51 to the position shown in Fig. 1 so that the trolley 55 may be moved along the cross arm 57 to aline the opening 67 in the cover lid 53 with a second rod to be undulated. The box-like support 51 is then raised to permit the spring catch 63 to engage the notch 65 and lock the travelling heater in position to heat the second rod. Generally, a plurality of the cross bars 13 is provided so that each damp rod to be formed is disposed between a pair of such cross arms. The number of damp rods to be employed in a grid structure depends upon the over-all size of the grid structure and the diameter of the strands 19. Three such damp rods will usually sulfice in an average size grid structure.

While the grid strands 19 have been referred to as substantially uniformly spaced, it is to be understood that the spacing may he graduated to compensate for deviations in the angle of incidence of the electron scanning beam between the axis and the edges of the target area.

What is claimed is:

l. The method of forming a grid of substantially taut ands disposed in a common plane to undulate an rod which comprises the steps of displacing adjacent strands in opposite directions from the common plane, inserting the elongated rod between the dis placed strands, applying pressure against the rod from opposite directions through adjacent strands, progressive- 1y applying heat at local regions to the rod to reduce it at heated regions to a softened state so that undulation occurs as the taut displaced strands return to the common plane, and thereupon progressively discontinuing the heating at the local regions so that the rod will harden in the undulated shape.

2. The method of fabricating a grid of taut strands stressed in a common plane to undulate an elongated vitreous rod which comprises the steps of displacing adjacent strands in opposite directions from the common plane, inserting said rod between the displaced strands subjecting the elongated rod to pressure applied from opposite directions through adjacent strands, heating the rod to soften it at the successo that rod undulation occurs as lowing softening so that rod hardening occurs with the undulated shape preserved.

3. The method of constructing a vibrationally damped grid for focusing beams of electrons on the target of a cathode-ray tube which comprises the steps of constructing a grid of tautly stretched substantially parallel and coplanar wires, elastically displacing said wires from their coplanar relationship and inserting a substantially straight thermoplastic insulating rod between the displaced wires to interweave said rod therewith, applying heat to only the portion of said grid including said rod until the rod becomes sufliciently plastic to deform and permit the wires to return to their coplanar relationship, and thereupon discontinuing the application of heat to permit hardening of the rod in its deformed state.

4. The method of constructing a vibrationally damped grid for focusing beams of electrons on the target of a cathode-ray tube which comprises the steps of constructing a grid of tautly stretched substantially parallel and coplanar wires, elastically displacing said wires from their coplanar relationship and inserting a substantially straight thermoplastic insulating rod between the displaced wires to interweave said rod therewith, applying heat from a concentrated source to said rod and moving said source relatively along said rod at a rate such as to render said rod sufiiciently plastic where the heat is applied to deform and permit the wires to return to their coplanar relationship and immediately thereafter harden as the source passes.

5. The method of vibrationally damping a cathode-ray tube color-control grid structure formed of a multiplicity of substantially parallelly positioned linear conductors normally held in tension in substantially coplanar relationship while strung across the window area of a frame the inner dimensions of which encompass and bound the tube raster to be scanned, which comprises the steps of interweaving a vitreous rod through the stretched linear conductors in a direction generally transverse thereof so that the conductors are displaced relative to their normal plane with substantially one-half of the conductors moved to one side of the normal plane and one-half moved to the other side of the normal plane, the maximum conductor displacement at each side of the normal plane being at the contact point between the vitreous rod and the conductor and being for a distance corresponding to one-half the transverse dimension of the vitreous rod plus one-half the conductor diameter so that the tensioned and displaced conductors tightly hold the rod, applying heat to the rod at localized regions along its length, progressively moving and shifting the region of heat application along the rod length, and limiting the heat application period at each region to a time only sufficient to render the heated rod portion plastic thereby to permit the tensioned linear conductors progressively to return to their normally c0- planar position and thereby progressively undulate the rod at heated regions along its length after which the rod immediately hardens in its undulated state due to heat removal and is tightly held by the conductors with which it is interwoven.

6. The method of vibrationally damping a cathode-ray tube color-control grid structure formed of a multiplicity of substantially parallelly positioned linear conductors normally held in tension in substantially coplanar relationship while strung across the window area of a frame the inner dimensions of which encompass and bound the tube raster to be scanned, which comprises the steps of interweaving a vitreous rod between the stretched linear conductors in a direction generally transverse thereof so that adjacent conductors are displaced in opposite directions relative to their normal coplanar relationship against the tensioning force exerted thereon with the maximum conductor displacement from normal coplanar state being at the contact point between the vitreous rod so that the tensioned displaced conductors tightly hold the rod, applying heat to the red at localized regions along its length, progressively moving and shifting the region of heat application along the rod length, limiting the heat application period at each region to a time only suificient to render the heated rod portion plastic thereby to permit the tensioned linear conductors progressively and sequentially to return to their normally coplanar position and thereby progressively undulate the rod along its length immediately following heating after which the rod hardens in its undulated state due to heat removal and is held in relatively tight contact with the tensioned conductors.

References Cited in the file of this patent UNITED STATES PATENTS 2,121,939 Williams June 28, 1938 2,239,546 Black et al Apr. 22, 1941 2,310,537 Morrison Feb. 9, 1943

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