US 3073886 A
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Description (OCR text may contain errors)
Jan. 15, 1963- H. J. MURPHY 3,073,886
TUBE SHIELD Filed July 13, 1956 INVENTOR f/OWI/FbJ/WOAM ATTORNEY United States Patent 3,073,886 TUBE SHIELD Howard J. Murphy, 326 Ballardvale St., North Wilmington, Mass. Filed July 13, 19-56, Ser. No. 597,728 5 Claims. (Cl. 174-35) The present invention relates to an improved electrical shield construction, and more particularly to an improved tube shield construction for association with electron discharge tubes or the like in electrical apparatus to avoid undesirable reactions between the various elements thereof.
A wide variety of shielding means, generally identified as tube shields, have been employed heretofore in electrical apparatus, such as, for example, radio sets, to dissipate electro-magnetic and electrostatic fields set up therein by the electron discharge tubes during the operation of the apparatus. While such prior tube shields adequately perform their intended shielding function, such tube shields have possessed many disadvantages which have been found objectionable.
One of the most common forms of tube shields heretofore employed has consisted of a simple can or cylinder which is secured to the chassis in detachable relationship therewith by a friction fit or similar fastening means. When a tube is to be replaced in an apparatus employing the so-called can type tube shield, the tube shield is completely detached from the chassis of the apparatus, after which the tube is then replaced. Oftentimes the repairman or technician performing the operation will fail to replace the tube shield with a corresponding impairment in the operation of the apparatus. Moreover, the failure to replace the tube shield invariably results in the tube shield being left on the chassis, thereby resulting in the likelihood of a short circuiting of the electrical apparatus. Another disadvantage with the can type tube shield is that the continued insertion and withdrawal of the tube shield from time to time during the replacement results in a loose conection between the tube shield and the chassis. This will result in a vibration of the tube shield, oftentimes not insuring a positive grounding of the shield to the chassis.
Another detachable form of the tube shield that has received widespread usage is the so-called shaped shield. This type consists of two symmetrically paired parts of sheet metal and shaped to fit closely to the bulb of the tube. The paired parts are held together by a detachable ring, a detachable collar, or various other forms of clamping and connecting parts. Such shaped tube shields, in addition to the basic disadvantages attendant to detachable tube shields in general, suffer further in that all tubes are not one size. Therefore, several different sizes must be made and stocked, resulting in an unnecessary inventory. Moreover, the design and multiplicity of parts of the shaped tube shields have resulted in a relatively high cost for such shields.
Some attempts have been made to eliminate these disadvantages attendant to the various forms of detachable tube shields fixedly securing the tube shields to the chassis. Such fixed tube shield constructions have consisted of two mating or paired parts, each of which are hingedly conected at their bottom ends to one another or to the chassis. To replace a tube in an electrical apparatus employing such a construction, each of the mating parts is pivoted upwardly away from one another, the tube then replaced, and the component parts then pivoted inwardly to one another to envelope and shield the new tube. A principal disadvantage with this type of tube shield is that it is extravagant of chassis space and does not permit the positioning of the tubes to the manufacturers require- 3,073,886 Patented Jan. 15, 1963 ments. Another disadvantage with this form of shield is that latching or connecting means between the mating parts to insure proper engagement of the shield parts must be present, thereby increasing the complexity and cost of such tube shields. tube shields heretofore developed have met with very little success since compactness of design and simplicity of construction are necessities in most electrical apparatus.
It is therefore a principal object in the elimination of the foregoing and related disadvantages to provide a new and novel tube shield construction overcoming the disadvantages attendant to previously employed tube shields.
Another object of the present invention is the provision of an improved tube shield construction which will permit replacement of a tube more easily than with prior tube shields.
Yet another object of the present invention is the provision of an improved tube shield construction which will be permanently affixed to the chassis, thereby insuring the proper functioning of the tube shield at all times.
A further object of the present invention is the provision of an improved tube shield construction that requires a minimum amount of chassis space.
A still further object of the present invention is the provision of an improved tube shield construction in which the component parts will be in proper engagement with one another at all times.
Another object of the present invention is the provision of an improved tube shield construction that will remain in tight engagement and in proper grounded relationship with the chassis at all times.
A still further object of the present invention is the provision of an improved tube shield construction that is of extreme simplicity in design and operation, and inexpensive to manufacture.
Other and additional objects will become apparent from the ensuing description taken in conjunction with the accompanying drawings.
Broadly stated, in the attainment of the foregoing related advantages, a tube shield construction of the present invention comprises a metal sleeve means in the form of a longitudinally or axially compressible telescoping helix and connecting means secured at the bottom end thereof for securing same to a support.
To the accomplishment of the foregoing and related ends, the present invention then consists of the means hereinafter fully described and particularly pointed out in the claims, the annexed drawing and the following description setting forth in detail certain means in the carrying out of the invention, such disclosed means i1- lustrating, however, but one of various ways in which the principle of the invention may be employed.
The present invention is illustrated by way of example in the accompanying drawings, in which:
FIGURE 1 is a perspective view of a tube shield construction made in accordance with the present invention in unattached relationship.
FIGURE 2 is a front elevation of the tube shield construction shown in FIG. 1 attached to a support and in operating relationship.
FIGURE 3 is a front elevation of the tube shield construction shown in FIGURE 2 in an axially compressed state to permit the withdrawal or replacement of an electron discharge tube.
Reference is now to be had to the drawing wherein an illustrative embodiment of a tube shield construction made in accordance with the present invention and generally designated by reference numeral 10 is shown. The tube shield construction 10 comprises a body portion 11 made in the form of an axially compressible helix which Therefore, the permanently afiixed.
in its normal uncompressed state is of a height corresponding to that of the electron discharge tube to be shielded. The bottom edge of the body portion 11 is provided with securing means, such as a connecting tab 12, for securing the same to a support.
The body portion 11 may be made from any suitable strip metal stock capable of being axially compressed or telescoped. As shown in FlGURE 1, the body portion 11 includes a first course 13 in which a portion of its bottom edge is at right angles to the connecting tab 12, and will serve to engage the surface of the support properly. The second course 14 is a continuation of the first course 13, and is in inclined relationship thereto. The second course 14 is of a lesser diameter than that of the first course i3, and is in overlapping relationship thereto. The third course 15 likewise is inclined with respect to the second course 14, and is also of a lesser diameter, with the diameter of the fourth course 16 being less than that of course 15, with each course lying in overlapping inclined relationship with one another to insure positive shielding.
The tube construction 1% is preferably formed by employing a piece of metal ribbon and angularly winding same upwardly so that it will be of diminishing scope in cross-section with the inside diameter of the final course being greater than the tube diameter of the electron discharge tube. In this construction, a longitudinal or axial compression of the formed helix results in the body pordon-10 is a compressed state to a height generally corresponding to the height or width of the metal strip employed which will be ample to permit the replacement of a tube.
To secure the tube construction it} to a support 17, the
securing tab 12 is inserted in a slot immediately adjacent the socket opening and bent outwardly therefrom against the under surface of the support 17, as shown in FIG URES 2 and 3, thereby locking the first course in tight relationship to the support. In its normal position the body portion 11 will be in an unflexed or uncompressed state, and will be of a height sufiicient to adequately shield the electron discharge tube 13. When it is desired to replace a tube, the fourth course 16 is compressed downwardly toward the base 17, resulting in each of the courses 1346 telescoping within one another until the body portion 11 is of a height corresponding to that of the first course. The tube is then grasped, Withdrawn, and replaced, and the hand holding the body portion 11 is then released. The body portion 1 will then snap back into its original position, as shown in FIG. 2, to-
provide the necessary shielding.
While in the illustrative embod ment the volute has its wider end secured to the support 17, it will be apparent that the narrower end may be so secured, as may be desirable for the conservation of space when an upwardly enlarging tube is to be shielded. However, when shielding cylindrical tubes, it is preferable to have the narrower end of the volute uppermost, as the volute can then most readily be collapsed with the backs of the fingernails while the fingers grasp the tube to remove or insert it.
While there have been described herein what are at present considered preferred embodiments of the invention, itwill be obvious to those skilled in the art that modifications and changes may be made therein without departing from the essence of the invention. It is therefore to be understood that the exemplary embodiments are illustrative and not restrictive of the invention, the
scope of which is defined in the appended claims, and that all modifications that come within the meaning and range of equivalency of the claims are intended to be included therein.
1. In an electrical apparatus having a support, a tube socket associated with said support for receiving an electron discharge tube therein and -a tube shield construction positioned adjacent said socket in shielding relation to a tube when positioned therein, the improved tube shield construction comprising a sleeve member in the form of an axially compressible volute of conductive material having a plurality of wound, overlapping courses decreasing in cross section from the bottom to the top and open at both ends thereof, and connecting means secured at the bottom end thereof for securing same to the support in said shielding relation.
2. The invention of claim 1 in which the bottom turn of said volute has a bottom edge lying in a plane at right angles to the axis of the volute.
3. In combination, a chassis, a socket secured thereto and a shield for an electronic component adapted to be mounted within said socket, said shield surrounding said socket and comprising a helioally wound strip of conductive metal, the adjacent turns of the helix being in overlapping relation to provide a shield for said component, said shield being axially collapsible on application of pressure with the successive turns nesting into adjacent turns, and mounting means for said shield secured thereto at the margin of at least one end thereof, said mounting means comprising at least one tang integrally extending from one edge of said metallic strip at the section thereof forming an end turn of said helix, an opening in said chassis adjacent said socket, said tang extending through said opening and permanently securing said shield to said chassis.
4. In combination, a chassis and a shield for an electronic component comprising a helically wound strip of metal, said shield being collapsible on application of pressure with successive turns nesting into adjacent turns, and mounting means for said shield secured thereto at the margin of at least one end thereof, said mounting means permanently securing said shield to said chassis.
5. In combination, a chassis and a shield for an electronic component comprising a helically wound strip of metal, said shield being collapsible on application of pressure with successive turnsnesting into adjacent turns, and mounting means for said shield secured thereto at the margin of at least one end thereof, said mounting means comprising tang means extending from one edge of said metallic strip at the section thereof forming an end turn of said helix, and tang receiving opening means in said chassis; said tang means extending through said opening means and permanently securing said shield to said chassis.
References Cited in the file of this patent UNITED STATES PATENTS 1,049,199 Bowman Dec. 31, 1912 1,270,462 Thueringer June 25, 1918 2,488,244 Shea Nov. 15, 1949 2,646,460 Del Camp July 21, 1953