US3371303A

US3371303A - Adjustable mounting for tuning member

Info

Publication number: US3371303A
Application number: US544421A
Authority: US
Inventors: Gerald S Fay
Original assignee: Arris Technology Inc
Current assignee: Arris Technology Inc
Priority date: 1966-04-22
Filing date: 1966-04-22
Publication date: 1968-02-27
Anticipated expiration: 1985-02-27

Description

Feb. 27, 1968 G. s. FAY 3,371,303

ADJL'S'I'ABIJE MOUNTING FOR TUNING MEMBER Filed April 22, 196e INVENTOR. Geven@ s. 14/

, frafP/ve'y United States Patent 3,371,303 ADJUSTABLE MOUNTING FOR TUNING MEMBER Gerald S. Fay, Springfield, Mass., assignor to General Instrument Corporation, a corporation of Delaware Filed Apr. 22, 1966, Ser. No. 544,421 19 Claims. (Cl. 336-130) The present invention relates to an improved construction for mounting a tuning member in a manner such that it may readily have its position adjusted, and will then reliably remain in that position.

In many communication system tuning devices a movable part carries a tuning member such as a ferromagnetic core, and moves it relative to a iixedly mounted tuned member, thereby to vary the electrical character of the tuned member and produce the desired tuning effect. In soi-called gang tuning, where a plurality of tuning members are simultaneously moved relative to a corresponding plurality of tuned members, proper tracking among the tuned members as the System is tuned from one end of its range to the other requires that the positions of the tuning members relative to the moving part on which they are mounted be adjustable from unit to unit. Slight variations in the physical or electrical characteristics of the mounting structure, the tuned members and the tuning members make this type of adjustment inevitable and ine-scapable.

One common type of tuned element is a helical inductance wound about a coil form. The tuning member associated therewith generally constitutes a member telescopically into or over the helically wound coil; in one conventional form it comprises a core formed of ferromagnetic material which slides inside the tubular form on which the coil is wound. When tuning with devices of this type a further problem is presented, that of alignment of the coil form with its corresponding telescoping member. It is desirable that the telescoping cores be fairly snugly received within the coil forms, and it is essential that they be freely slidable to different tuning positions. Means must be provided to compensate for slight misalignments of core and coil form if effective tuning is to result.

Various proposals have been made to provide for individual adjustability of the cores relative to the part on which they are mounted. They generally involve the attachment to the core of a connecting member, usually rod-like in form, which extends through an aperture in the mounting part, and structure is provided to permit axial adjustment of that element as it passes through the aperture. To compensate for slight axial misalignments of the tuning core and its corresponding coil form it has been proposed that the connecting member be resiliently flexible, and to that end it is often defined by a helically wound metallic wire the adjacent turns of which are preferably in contact with one another, thereby fixing its normal length, the wound wire rod being resiliently bendable along its length.

In the past the structure which has provided for adjustable mounting of these flexible connecting rods as they pass through the aperturel in the mounting parthas added significantly to the cost of the tuner. Such structure either involves the use of parts other than the mounting part and the connecting rod (such as setscrews, locking nuts or resilient inserts adapted to grip the connecting rod) or the carying out of time consuming fabrication operations (such as the internal threading of the inner surface of the aperture and the formation and threading of apertures for the setscrews), or both.

It is the prime object of the present invention to provide a mounting for rod-supported tuning members which not only provides for ready individual adjustability of high degree of security of retention of such tuning members in their adjusted position, but which also is the ultimate in simplicity and adds virtually nothing to the cost of the unit.

The commercial significance of cost in units of the type under discussion cannot be over-emphasized. The manufacture of tuners is an extremely competitive business. Tuners are used by radio set manufacturers in extremely large numbers, and a difference of a fraction of a cent in the cost of manufacture of a tuner often makes the difference between making and losing a sale for hundreds of thousands of such tuners. Consequently anything which saves even a small amount of money in manufacturing cost is of prime importance. The commercial situation is, of course, greatly complicated by the equal emphasis on quality and reliability. It is not enough that a tuner be less expensive than -a competitive item; it must also function at least as accurately and reliably as the competitive item. The significant fact about the construction here diS- closed and claimed is that it signally satisfies both the requirement of lack of expense and the requirement of reliability.

In accordance with the present invention the mounting part is provided with an aperture, and the connecting rod between the tuning member and the movable part on which it is mounted is resiliently flexible and is provided on its external surface with a thread. Most conveniently it may be formed of helically wound relatively stiffiy resilient wire, such as has been used in the past. However, the present invention departs from the prior art in that the aperture in the mounting part need not be provided with a threaded inner surface; thus it need only be drilled or otherwise formed, but it does not need to be tapped, thus eliminating a manufacturing operation and therefore reducing cost. The externally threaded connecting rod passes freely, but preferably not loosely, through this aperture. The mounting part is further provided with an interference element which is rearwardly spaced from and at least partially overlaps the rear end of the aperture. This element has a surface which engages and dcects that end of the connecting rod which has passed through the aperture, thus forcing the opposite surface of the connecting rod against an edge of the aperture, one or the other or both of said element surface and said aperture edge therefore functioning as a screw thread which cooperates with the external thread on the connecting rod. This permits accurate adjustment of the position of the tuning member relative to the part through rotation of the connecting rod, just as though the aperture in the mounting part had been internally threaded. Moreover, the force exerted by the interference element on the connecting rod where those two parts engage, as well as the force exerted on the connecting rod by the aperture edge against which it is pushed by the interference element, act to friction-ally retain the connecting rod in its adjusted position, thus reliably ensuring that the tuning member will stay where it belongs. These results, it will be noted, are achieved by means of a structure which may be molded or cast in one piece, thus not only reducing material cost, but also greatly reducing assembly cost.

To the accomplishment of the above, and to such other objects as may hereinafter appear, the present invention relates to a means for mounting a tuning member on a movable part, as defined in the appended claims and as described in this specification, taken together with the accompanying drawings in which:

the tuning members relative to the mounting part and a v FIG. 1 is a front elevational view, partially schematic, of a tuner in which the present invention is embodied;

FIG. 2 is a cross sectional view on an enlarged scale, taken along the line 2-2 of FIG. l; and

FIG. 3 is a fragmentary end elevational View of the mounting part alone, taken from the left-hand end of FIG. 2.

FIG. 1 discloses, more or less schematically, a tuner comprising a chassis support 2 on which are mounted a plurality of tuned members generally designated 4, each of these tuned members in the form here specifically disclosed comprising a tubular coil form 6 mounted on the chassis supportZ, that coil form having a tuning coil S wound over the exterior thereof, the coil form 6 having a hollow interior 1f). Associated with each tuned member 4 is a tuning member generally designated 12 here disclosed, as is conventional, in the form of a core 14 formed of ferromagnetic material which is adapted to be relatively snugly telescopical slidably received within the hollow interior 10 of its associated coil form 6. As will be apparent, the degree to which the core 14 is telescoped within the coil form 6 will cause the inductance of the coil S to vary, thus producing a tuning effect.

A movable mounting part generally designated 16 is here shown in the form of a structural element having a cross bar 18 which is adapted to be moved toward and away from the upper ends of the coil forms 6. The part 16 is mounted in any appropriate manner in the tuner and is moved toward and away from the upper ends of the coil form 6 by any appropriate mechanism in order to simultaneously tune all of the tuned members 4. The cores 14 defining the tuning members 12 are therefore all connected to the cross bar 18, that connection being accomplished by connecting rods generally designated 20 which are liexibly resilient and which have an outer surface which defines an external threaded configuration. 1n the form here specifically disclosed the connecting rods 20 are defined by tension springs formed of closely helically wound resilient metal wire, the external threaded configuration of the connecting rods being defined by the radially outwardly disposed surfaces of the wire turns. Preferably, but not necessarily, the turns of the helices axially engage one another so that the normal length of the thus-defined connecting rods 20 is fixed. One end of each rod 20 is secured to a tuning core 14, as by being embedded therein, as at 26; the other ends of the rods 20 are free.

The cross bar 18 on the movable mounting part provided with an upstanding wall 22 having a series of apertures 24 therethrough, the apertures 24 being aligned with the open ends of the coil forms 6 and being of approximately the same size as the maximum external diameter of the connecting rods 20, so that the connecting rods. 20 can be relatively snugly received within the apertures 24, while at the same time being more or less freely axially movable therethrough. It is a feature of the present invention that the internal surface of the apertures 24 need not be threaded, although threads may be there provided if desired. The structure of the present invention will function in an entirely satisfactory manner even with a smooth sided aperture 24, as is here specifically disclosed.

Each aperture 24 has a front end which faces the corresponding coil form 6 and a rear end defined at least in part by an upper corner edge 28. The cross bar 18 of the movable mounting part 16 also carries a series of interference elements which are located rearwardly spaced from the rear end of the apertures 24 and which partially overlap said rear aperture ends. As here specifically disclosed interference elements 30 overlap the lower portions of the rear aperture ends, at a point diagonally opposite from the upper corner edges 28 of the apertures 24. Side walls 32 extend rearwardly from the rear ends of the apertures 24 for a short distance, the upstanding wall 22, the apertured parts thereof, the interference elements 3f) and the side walls 33 all preferably being integrally formed to define a single easily molded structure, as may best be seen from FIGS. 2 and 3.

When a given tuning member 14 is to be secured to the mounting part 16 the free end of its connecting rod 20 is passed through the aperture 24 from the front end to the rear end thereof. When the tip of the connecting rod 20 appears in the axial space between the rear aperture end and the interference element 30 it is lifted so as to clear the interference element 30. This causes the resiliently fiexible connecting rod 20 to bend upwardly about the upper corner edge 28vof the aperture 24, that edge 28 then engaging and cooperating with the external thread on the connecting member 20, producing in effect a threaded interengagement between connecting rod 20 and part 16 despite the fact that the aperture 24 is not internally threaded'I-Ience the precise positioning of each tuning member 14 relative to the part 16 may be accurately achieved through rotation of the connecting rod 20 relative to the part 16.

The free end of the connecting rod 20 will extend axially beyond the interference element 30, and the resiliency of the 'connecting rod 2t) will cause its free end to engage with the upper surface, and usually the upper forward corner, of the element 30. This will produce a second area of threaded engagement between the connecting rod 20 and the part 16, and it will further ensure so firm an engagement between the connecting rod 20 and the interference element 30 and between the connecting rod 20 and the upper corner edge 28 of the aperture 24 as to reliably frictionally retain the connecting rod 20 in any adjusted position in which it may be placed. The side walls 32 prevent the free end of the connecting rod 20 from moving laterally, and thus prevent it from escaping from the interference element 30.

When, as is here disclosed, the connecting rod 20 is formed of a helically wound spring, the axial deformation of that rod at the upper corner edge 28 of the aperture 24 and at the active surface of the interference element 30 will tend to cause adjacent turns o-f the helical coil to separate, thus producing a vvery firm and positive threaded interengagement between the appropriate surfaces of the mounting part 16 and the corresponding areas of the connecting -rod 20, thus enhancing the degree of security provided against accidentalV shifting of position.

It is noteworthy that in the products of the present invention no tapping operations need be performed, no

`extra parts need be made or purchased, assembly operations are entirely eliminated, and thus cost is greatly minimized, but without any significant sacrifice in ease of adjustment of the positions of individual tuning members 12 or the security of that adjustment when once made.

While but a single embodiment of the present invention has been here specifically disclosed it will be apparent that many variations may be made therein, all within the scope of the instant invention as defined in the following claims.

I claim:

1. In a tuner comprising a support, a tuned member mounted thereon, a tuning member movable relative to said tuned member to tune the latter, a part operatively connected to said support and movable relative thereto, and means connecting said tuning member to said part for movement therewith', the improvement which cornprises said part having an aperture with front and rear ends respectively operatively facing toward and away from said tuning member, an element on said part rearwardly spaced from and at least partially overlapping said rear end of said aperture, and said connecting means comprising a resilient member the outer surface of which defines an external threaded configuration, said resilient member passing through said aperture and engaging and being deflected by said element.

2. The tuner of claim 1, in which the maximum external diameter of said resilient member is not appreciably greater than the internal diameter of said aperture.

3. The tuner of claim 2, in which an edge of said element engages said resilient member between adjacent external threads thereon.

d. The tuner of claim 2, in which an edge ot said element and an edge or" said rear end of said aperture engage said resilient member between adjacent external threads thereon.

5, The tuner of claim 2, in which the resilient-memberengaging Surface of said element is concave, said member being received within said concavity.

6. The tuner of claim 2, in which an edge of said element engages said resilient member between adjacent external threads thereon, and in which said edge of said element is concave, said member being received within said concavity.

7. The tuner 01' claim 2, in which an edge of said element and an edge of said rear end of said aperture engage said resilient member between adjacent external threads thereon, and in which said edge of said element is concave, said member being received within said concavity.

8. The tuner of claim in which the maximum eX- ternal diameter of said resilient member is not appreciably greater than the internal diameter of said aperture, and in which said element is spaced rearwardly from said rear end of said aperture by a distance greater than the diameter of said resilient member.

9. The tuner of claim 8, in which an edge of said element engages said resilient member between adjacent external threads thereon.

1b. The tuner of claim 8, in which an edge of said element and an edge ot said rear end of said aperture engage said resilient member between adjacent external threads thereon.

11. rThe tuner of claim Si, in which the resilient-member-engaging surface of said element is concave, said member being received within said concavity.

12. The tuner of claim S, in which an edge of said element engages said resilient member between adjacent external threads thereon, and in which said edge of said element is concave, said member being received within said concavity.

13. The tuner or" claim 3, in which an edge of said element and an end of said rear end of said aperture engage said resilient member between adjacent external threads thereon, and in which said edge of said element is concave, said member being received Within said concavity.

14. The tuner or" claim 1, in which an edge of said element engages said resilient member between adjacent external threads thereon.

15. The tuner of claim 14, in which the resilient-member-engaging surface of said element is concave, said member being received within said concavity.

16. The tuner of claim 1, in which an edge of said element and an edge of said rear end of said aperture engage said resilient member between adjacent external threads thereon.

17. The tuner of claim 16, in which the resilient-member-engaging surface of said element is concave, said member being received within said concavity.

1%. The tuner of claim 1, in which the resilient-member-engaging surface of said element is concave, said member being received within said concavity.

19. The tuner of claim 1, in which said resilient member comprises a helicaily wound resilient length, adjacent turns of which deline said external threaded configuration.

Reierences Cited UNITED STATES PATENTS Aug. 18, 1960.

LARAMIE E. ASKIN, Primary Examiner. T. I. KOZMA, Assistant Examiner.

Claims

1. IN A TUNER COMPRISING A SUPPORT, A TUNED MEMBER MOUNTED THEREON, A TUNING MEMBER MOVABLE RELATIVE TO SAID TUNED MEMBER TO TUNE THE LATTER, A PART OPERATIVELY CONNECTED TO SAID SUPPORT AND MOVABLE RELATIVE THERETO, AND MEANS CONNECTING SAID TUNING MEMBER TO SAID PART FOR MOVEMENT THEREWITH; THE IMPROVEMENT WHICH COMPRISES SAID PART HAVING AN APERTURE WITH FRONT AND REAR ENDS RESPECTIVELY OPERATIVELY FACING TOWARD AND AWAY FROM SAID TUNING MEMBER, AN ELEMENT ON SAID PART REARWARDLY SPACED FROM AND AT LEAST PARTIALLY OVERLAPPING SAID REAR END OF SAID APERTURE, AND SAID CONNECTING MEANS