US2911458A - Captivated tube shield - Google Patents

Description

Nov. 3, 1959 w. H. McKEE CAPTIVATED TUBE SHIELD Filed Oct. 21. 1955 VENTOR ZSOAA.

ATT NE Y the under surface of the chassis.

4 Claims. Cl. 174-35 This invention relates to a shield for electron and 1 ,United States Patentc) Patented Nov. 3, 1959 gaseous discharge devices, and more especially to a tube shield intended to be permanently secured to a chassis or tube socket so as to be non-removable-that is, a captivated tube shield. The shield of this invention has utility with tubes whatever their environmental setting,

but is particularly useful in connection with printed wire circuits.

In conventional radio and television sets and other electronic equipment, the tubes ordinarily extend above the top surface of a metal chassis, while the leads, terminals and circuit components (such as resistors, capacitors, coils, etc.) are positioned beneath and extend along In such an arrangement, no open terminals and leads are along the top of the chassis, and if a tube shield is removed from its position-about the tube and is carelessly laid on the top of the chassis, there is no danger that the tube shield will short out a terminal or lead having a potential substantially above that of the chassis.

' Printed wire circuits are gradually replacing the usual metal chassis and lead wires in present electronic equipment. In these structures, printed wires extend along one or both sides of the printed circuit panel board or chassis, but in addition to the tubes which extend above -'the upper side of the panel, terminals, jumper wires, circuit components, etc. are also frequently positioned along that side. This means that voltages are present and shorting could occur between certain of the components, jumper wires, terminals, etc. 1

As a result of this, underwriters are beginning to require the use of tube shields that are permanently aflixed to the printed wire circuit panels so that they cannot be removed therefrom and laid temporarily on the panel where, if a repairman forgets them, they could cause shorting and thereby create fire hazards. It is known that attempts have been made to provide tube shields that are captivated or permanently affixed to the printed wire panel board, but attempts heretofore made have not resulted in a captivated tube shield that is satisfactory. In the form most frequently found, for example, the tube shield is made in sections that are longitudinally telescopic, and when it is desired to remove or replace the tube, the normally extended telescopic sections are pushed together to expose the upper end portion of the tube. Such an arrangement is not satisfactory because it is necessary to use but two telescoping sections, and in such an arrangement the sections when extended cannot be long enough to enclose the entire tube, for if they are nearly that long they cannot telescope together to such an extent that the upper end of the tube can be grasped with sufiicient force to enable it to be removed without great effort.

A need exists for a captivated tube shield that will overcome the disadvantages in prior art structures and satisfy the requirements imposed thereon, and it is ac cordingly an object of this invention to provide such a tube shield. Another object of the invention is in the above the tube to completely enclose the same, yet which permits the tube enclosed thereby to be grasped when necessary to easily and readily remove the same from position in its socket.

Still another object is that of providing a captivated or permanently atlixed shield of the character described having windows and shutters for selectively opening and closing the windows, the windows being opened to permit a tube within the shield to be grasped for removal. A further object of the invention is in the provision of a tube shield comprising telescoped sections rotatable with respect to each other, one ofthe sections having windows therein oriented on opposite sides thereof and the other providing sections adapted to close over the windows in normal use, but when rotated slightly to open the windows to expose-portionsof a tube within the shield. Additional objects and advantages will appear as the specification is developed.

Embodiments of the invention are shown in the accompanying drawing, in which:

Figure l is a perspective view showing a tube shield embodying the invention secured to a printed wire circuit board about a tube socket, and with a tube positioned within the shield; Figure 2 is a perspective view similar to that of Figure 1, but showing the windows of the shield open and a tube being withdrawn from within the shield; Figure 3 is a vertical sectional view taken along line 3-3 of Figure 1; Figure 4 is an exploded perspective view of theshield structure shown in Figures 1 through 3; Figure 5 is a transverse sectional view taken on the line 5-5 of Figure 3; Figure 6 is an exploded perspective view of a modified form of tube shield embodying the invention; and Figure 7 is a vertical sectional view taken along the longitudinal axis of the modified form of tube shield illustrated in Figure 6, but with the parts thereof in their functional position.

The tube shield illustrated in Figures 1 through 5 is designated generally with the numeral 10, and is shown in position upon a printed Wire circuit panel or chassis designated with the numeral 11. In Figure 3, the relative positions of the tube shield, chassis and a tube socket are shown, and the socket (which is illustrated in broken lines) is designated with the numeral 12. Both Figures 1 and 2 show a tube within or partially within the tube shield, and for identification the tube is indicated with the numeral 13.

It will be appreciated that the tube shield 10 can be employed as a shield with any tube, whether an electron along the bottom surface thereof with a plurality of printed wires 14 that are connected to prongs 15 of the tube socket 12, preferably in a solder connection that then serves also to rigidly anchor the tube socket to the printed wire chassis. As is apparent from Figure 3, the

prongs 15 of the tube socket extend through appropriate apertures properly oriented and provided in the chassis 11, and the printed wires 14 terminate about these openings.

The tube shield 10 preferably serves, as is shown in Figure 1, to completely enclose a tube 13, thereby increasing the effectiveness of the shielding of such tube, and serving also to mechanically or physically protect the 7 upper end portion of the tube. The shield may be permanently aflixed to the chassis or tube socket or may be captivated in any desired manner, the important considera -.to the chassis or panel-11 by means of ears 16 which initially depend downwardly, as 'shown in Figure 4, so that they can be extended through apertures provided for ,that purpose in the paneL. When projectedtherethrough,

the ears 16 can be turned over-,-.asv indicated at 17, to abut .the under surfaces of the panel 11 and thereby anchor the shield in place. Preferably, the shield is grounded, as by connecting one of the ears to a ground wire as shown'in Figure 3. It will-be apparent that the mount- .ing means is illustrated as exemplary only, and other mechanical arrangements for locking-or anchoring the tube shield inplace can be employed.

In the illustration given, two ears 16 are provided, and these earscomprise downwardly turned end portionspof an elongated flange 18 that is provided along the collar 19 of the base 20 with which the inner tubular shell orwindow-equipped section 21 ofthe tube shield is equipped. In the form of'the structure shown in Figures 1 through 5, the inner shield section21 hasa reduced diameter above the base. 20 .and is provided with a pair of diametrically opposed windows. 22 and 23 that may be formed in any suitable manner. In the form shown,

lower edge of the outer shield section34, as isshown in Figure 7, vto limit downward movement thereof. In other respects, the modified form of tube shield is substantially the same as that heretofore described, but is shown in connection with a metal chassis 11a and a conventional tube socket 12a for use with such a chassis.

. The inner shield section 32 has Windows or openings 35 and 36, ears or holders 37,-a lower collar 38 at the base thereof, and anchor members -or ears-39 provided by a base flange 40. The outer section 34 is a straight vertical tube providing windows oropenings 41 and- 42 and shutter sections .43 and44-interposed therebetween. The lower collar 38, as seen best in Figure 7, is crimped about an annular, flange 45.0f the tube .socket,-and is then integral therewith. It will be apparent that the shield 10 might be so formed, and conversely the shield of Figures 6 and 7 might be arranged with a tube socket in the manner of shield 1t].

In use of either form of the structure, the inner and outer tube sections are assembled, and the ears or holders 24 or 37 are bent over.to lock the outer shield sec- "the window 22 is enclosed by .the. perimetric-edges that a t extend thereabout, while the window 23 is open at its:

tion. in- .telescopedposition about the inner sections, whilethe shoulders or stop members Hand .33 then bear ,upwardly against the outer shield section to limit downward movementathereof.- The tube .shieldis then anchored in position with respect to the chassis with .which itis employed, as for-example, by. bending over . thepears 16 or 39 after they have beenprojectedthrough .upper .end and may beformedl by. simply. providing a shortened sheet of. material that provides a gap between ythe ends thereof when the sheet isrolled into;a cylindrical:

: shape, as illustrated.

At its upper end, the inner shield section 21 is;provided with a pair of diametrically opposed ears orsshields 24. 4 adapted to be bent over .the upper edgeof the outer shield usectioneor shutter. ;section.25 of .the tubeshield which telescopically receives the inner shield section '21 therein.

The ears or holders 24, when bent overras-shown in FigureslQZ and 3, prevent separation .of the; shield sec 'tions, andv in particular limitorconstrain the outer shield section25 against upward movement with respect to the inner .section.

The outer shield-section25 has openings .or windows I thatextends between the lower enlarged base-and upper reduced end portion'ofthe innershield: section. 21, as is shown. in Figures 1,2. and 3. Engagement; of. the collar 30 and shoulder 31 limits or constrainszthe outer shield .:section 25 from downwardmovement with respect to W the innenshieldsections .While the sections are locked against relative longitudinal movement, they'are rotatable with respect to each other. One. or more dimples or protuberances 31a are provided to limit rotation of the outershield section in eitherxdirection within the limits of a predetermined .arc, and .ashillustrated; the dimples may. :be formed-.in the outer. shield section 'for engagehaveaa single diameter from end to end thereof, as is shown by'the innershield section 32-in-Figure 6, and in such case the outershieldsection might extend all the Way' to the" bottom of the inner'shieldsection and sit upon the lower collar thereof, or conceivably,-it might rest upon the top surface of the chassis 11.

"On the other hand, 'asis-shownin the modified form of structure in Figures 6' and 7, such :an inner shield section might have one or more; laterallystruckportions "or stop members 33 thereabout adaptedto engage the 26:and.27, and spaced therebetween opposedshutter or closure .portions 28 and .29. At: its lower end, the section 25:.is equipped with a' laterally extending. annular.

. flange or collar30 adapted to ;sit upon the shoulder 31 aligned openings inthe chassis.

To insert a tubewithin the shield, 'theouter tube .section is rotated so as to bring the openingsor windows 26. and 27,..respectively,.into alignment with the windows 22 and 23 (or. windows-.41 and 42, respectively, into alignment with the windows. 35 and 36.), anda tube is' then inserted into theshield. The tubemay begrasped through the aligned openings. inthe tube shield-on opposite sides thereof to guide the tube intoposition with respect to its tube socket, and to thereafter push the tube downwardly to. insert the prongsthereof-into the openings therefor in the tube socket. .The outer shield is then rotated to align the shutter ;or closure. sections thereof with the. windows of the inner tube shield.

The. result is a continuous bodyof. metal completely enclosing a tube to shield the same and offer, a path for magnetic and electrostatic fields to...ground. It will be appreciated that at leastone of theears or, anchor members of the tube shield willbe, connected to aground 1 wire. To remove the tube, the shield-sectionsare rotated with respect. to each other .to align theopenings. thereof, whereby the tube can be grasped between the fingers and drawn upwardly,'as shown luv-Figure 2.

It will be apparent that the specific; structures shown can be varied considerably, and parts maybe-reversedas, for example, by having the rotating shieldsection mounted within the stationary shield section, rather than as in-the structures shown.

While in the foregoing specification embodiments of the invention have been described in considerable detail.

for purposes of making a complete disclosureyit will be apparent to those skilled in the art that numerous changes may be made in those details without. departing from the spirit and principles of the invention.

- I claim:

l. A tube shield construction for shieldingan electron discharge tube associated with asupporteomprising an inner cylindrical shield member having a lowe'r base portion, connecting means atone end ofsaid lower base portion for-securing same to a support, stop means positioned immediately adjacent the upper endofsaid lower base portion, anupper body portion secured at one end to said lower base portion imediately adjacent the stop portion and extending upwardly therefromin longitudinal-alignment therewith, an outer cylindrical shield member of aheight substantially equal to said upper the bottom free end of said outer shield member being in engagement with said stop means to prevent longitudinal movement of said outer shield member in one direction, retaining means carried by one of said shield members in cooperation with the other of said shield members to prevent longitudinal movement of said outer shield member in the opposite direction, said upper body portion of said inner shield member and said outer shield member each having a pair of diametrically opposed longitudinally extending complementary slots of a width sufiicient to enable the fingers of an operator to grasp a tube positioned within said inner shield member, said outer shield member being rotatable with respect to said upper body portion of said inner shield member for selectively opening and closing said elongated slots.

2. A tube shield construction in accordance with claim 1 wherein the lower base portion has an outside diameter greater than the outside diameter of said upper body portion, with the stop means being in the form of a cirof said upper body portion with said base portion.

3. A tube shield construction in accordance with claim 1 wherein the lower base portion has an outside diameter substantially equal to the outside diameter of said upper body portion, and said stop means are in the form of a plurality of circumferentially spaced outwardly extending tab portions.

4. A tube shield construction in accordance with claim 3 in which the lower base portion immediately above the connecting means is provided with means to positively retain a tube socket therewith.

Brosilow et al. Nov. 13, 1934 Suller Nov. 5, 1935

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