US 3239184 A
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March 8, 1966 E. KIRKEBY 3,239,184
SUPPORT FORy LAMP Filed Feb. l, 1965 2 Sheets-Shree?I l INVENTOR Eivind Kirkeb Flg. 4 BY y ATTORNEYS March s, 1966 E. K|RKEBY 3,239,184
SUPPORT FOR LAMP Filed Feb. l, 1965 2 Sheets-Sheet 2 INVENTOR.
Eivind Kirkeby BY United States Patent O 3,239,184 SUPPORT FOR LAMP Eivind Kirlreby, Gladengveien 14, Oslo, Norway Filed Feb. 1, 1965, Ser. No. 429,533 Claims. (Cl. 248-286) This application is a eontinuation-in-part of application Serial No. 148,068, led October 27, 1961, now abanboned. This invention relates to equipoised lamps of the type having a pair of support arms which Aare pivoted together with one arm being swingably supported at a base construction and with the other `arm supporting a lamp assembly which includes an incandescent bulb or the like and a reflector shade. This invention is related particularly to counterbalanced support arm assemblies of the type used in lamps.
An object of this invention is to provide improved lamps of the above character. Another object is to provide improved counterbalance support arm assemblies of the type used with such lamps. A further object is to provide improved arrangements for utilizing a compact spring for counterbalancing lamps and the like. A further object is to provide for the above with a structure which is light in weight, compact, sturdy, efficient, and adaptable to various conditions of operation and use. These and other objects will be in part obvious and in part pointed out below.
In the drawings:
FIGURE 1 is a side elevation of one embodiment of the invention;
FIGURE 2 is a view on a larger scale of the counterbalance assembly shown in the lower portion of FIGURE 1, with the casing 'and certain other structure broken away;
FIGURE 3 is a view on the line 3 3 of FIGURE 2;
FIGURE 4 is `a fragmentary sectional view on the line 4-4 of FIGURE 2;
FIGURE 5 is a view similar to FIGURE 2 but showing another embodiment of the invention;
FIGURE 6 is a vertical cross-sectional View of the upper portion of FIGURE 5; and
FIGURE 7 is a View on the line 7-7 of FIGURE 6.
Referring to FIGURE l of the drawings, a lamp 2 has a mounting bracket 4 which is adapted to be clamped to a table or the like. Bracket 4 has a vertical bore 6, shown in broken lines, in which a pivot pin S (see also FIGURE 2) is snugly received to provide a vertical pivot for the lamp. A set screw 7 (FIGURE 1) in bracket 6 is adapted to be tightened against a ilat surface 9 (FIGURE 2) on the lower end of pivot pin 8, thus to hold the pivot pin from turning. However, when desirable the set screw may be omitted or it may be loosened so as to permit free turning of the pivot pin 8 within bracket 4.
Pivot pin 3 has an enlarged upper boss 11 by which it is mounted in the bottom of a counterbalance unit 1d which includes a horizontal pivot assembly 12 for a lower swinging arm 14. The upper end of arm 14 is connected by a pivot assembly 16 to an upper arm 18 upon the free end of which is mounted a lamp and shade assembly 2l). Assembly 2@ is mounted on arm 1S through a universal joint 22 so that the assembly may be turned around the longitudinal axis of arm 18 and may also be swung around a transverse pivot.
Pivot assembly 16 includes a pivot pin 24 (shown in broken lines) which is threaded rand has a thumb nut 26 which is tightened or loosened to adjust the pressure upon contacting friction anges upon the two arms 14 and 1%. Hence, by adjusting thumb nut 26 the freedom of swinging movement between the arms may be regulated. Arm 18 is biased upwardly (clockwise in FIGURE l) by a coil spring (not shown) positioned within arm 14 with its CII upper end connected to an overhanging extension on the end of arm 1S to the right of pivot pin 24. The lower end of the spring is connected to the lower portion of arm 14. This combination of a spring and an adjustable friction assembly provides a counterbalance arrangement for arm 18 and assembly 2t) upon arm 14. As indicated above, the present invention is concerned with the counterbalance and pivot structure at the lower end of arm 14.
Referring now to FIGURES 2 and 3, the pivot assembly 12, which supports arm 14 at its lower end, includes a rigid end shell 3d upon the lower end of arm 14, and this shell is journaled in the upper end of a casing 32 which is formed by two mating side casings 34 and 36. Side casings 34 and 36 provide a closed casing except for a slot at the top which is closed by a ange 31 on the end shell 3i). Hence, arm 14 may be swung throughout a substantial arc from the near vertical position of FIG- URE l counterclockwise to the broken line position.
Rigdly mounted in a boss 33 upon the inner surface of side casing 34 is a stub shaft 40 which has a threaded end which receives a thumb nut 42. End shell 3) has riveted to it a cam disc 44 and a friction disc 46 which are attached to a central `bore in the end shell by a sleeve 48 and a rivet (not shown). Sleeve 48 is journaled on stub shaft 4t), and end shell 3) is positioned against the end face of boss 33. The end of stub shaft 40 extends through an opening in side casing 36 and is held thereon by thumb nut 42. Friction washer 52 is positioned between friction disc 46 and the inner surface of side casing 35, and a smaller friction washer S4 is positioned on the outer surface of -side casing 36 beneath a spring washer S6 and thumb nut 42. Friction washers 52 and 54 are metal with a carbon coating and provide uniform friction under the pressure of the spring washer 56, and that pressure is adjusted by turning thumb nut 42.
Positioned beneath the pivot assembly 12 is a counterbalance coil spring d@ which has an anchor hook 62 on its upper end. Hook 62 is positioned upon cam disc 44 and acts as a cam follower. The lower end 64 of spring 60 extends inwardly of the coil and provides a seat for an adjusting nut 66 into which is threaded an adjusting screw 68. Screw 63 extends upwardly through a hole 70 in the bottom |wall 72 of side casing 34, and the hole is larger than the screw head '74 so that the wall provides a seat for the screw head. Hence, the tension on spring 60 is adjusted by turning screw 63 with a screw driver from below.
As indicated above, pivot pin 8 is mounted in counterbalance unit 1t) by a boss 11, and boss 11 is snugly received in a bore 75 in the bottom of side casing 34. The upper end of boss 11 has an arcuate extension 7S which rests against the top wall of bore 76 and provides a recess for head 74 of screw 68. Extension 78 (see also FIG-URE 4) also moves into engagement with a stop 79 to limit the relative rotary movement between boss 11 and side casing 34. Hence, when the lower end of pivot pin 8 is held stationary in bore 6 (FIGURE 1) by screw 7, the lamp may be swung around the vertical axis formed by pin 3, but that swinging movement is limited by the engagement (FIGURE 4) between extension 7S and stop 79.
Friction is provided against the rotation of boss 11 in bore '76 by a brake shoe Sii (FIGURES 2 and 4), which is mounted in a recess 82. Brake shoe Si) is held resiliently against the side of boss 11 by a spring 84 and an adjusting set screw 86. Brake shoe 80 has a lug 88 which projects into an annular slot Sit) in the boss, and this interengagement holds the boss in bore '76. Set screw 86 is turned to adjust the friction pressure against the boss, and it may be loosened to permit the brake shoe to move away from the boss so that lug 8S moves out of slot 90, thus to permit the removal of pivot pin 3 from the bore.
It has been indicated above that arm 14 may swing between a vertical position and a horizontal position, two such positions being illustrated in FIGURE 1. When arm 14 is in the full line position of FIGURE 1, cam disc 44 is positioned as shown in FIGURE 2. When arm 14 is swung counterclockwise, the cam disc is rotated around stub shaft 40, and the hook 62 on the upper end of spring 60 rises upwardly upon the cam disc, thus to extend the spring. Extending the spring causes a corresponding increase in the spring tension, and the cam disc acts as a crank arm urging arm 14 clockwise back toward the vertical position.
In considering the action of cam disc 44, the centers of stub shaft 40 and the cam disc are indicated at 92 and 94, respectively, and the cam disc acts as a crank arm having an etTective length of the distance between t-he two centers. With the arrangement shown the counterbalance effect resulting from the force of the spring acting through this crank arm tends to hold the lamp in any position to which it is moved. However, the friction produced by discs 52 and 54 is adjusted by turning thumb screw 42 and provide friction to augment the counterbalancing effect of the spring assembly and stabilize the action. As indicated above, the coil spring (not shown) within the lower arm 14 counterbalances the upper arm 18 with respect to the lower arm.
In the embodiment of FIGURES 5, 6, and 7, the lower arm 104 is pivoted in a casing 101 upon a shaft or bolt 102 through .a pair of cup members or end shells 103 xed to the end of the arm. Casing 101 is formed by a pair of side casings 101 and 101, and bolt 102 extends through the casing with the bolt head 125 and a thumb nut 121 holding the top of the casing together. There is a pair of washers 124 adjacent the side walls. Formed upon the opposite side walls of ends shells 103 are eccentric bosses or cams S, which are in frictional contact with washers 124. Hence, thumb nut 121 may be turned to adjust the friction between washers 124 and cams 105.
Riding upon cams 105 are the two hook portions 106 of a double lhook member, which is formed of rigid wire and has a downwardly hanging central loop 107. A tension coil spring 108 is attached to loop 107 by an end eye at its upper end and has an end plug 109 at its lower end. Plug 109 has a threaded axial bore into which an adjusting screw 110 is threaded, and screw 110 extends through an opening in a transverse casing wall 130 with the screw head 132 resting against -t-he bottom of the wall. Hence, the tension of spring 108 may be adjusted in the same manner in which the tension upon spring 60 (FIGURE 2) is adjusted.
The bottom portion 111 of casing 101 is mounted about a vertical pivot upon the cylinder portion 112 of a mounting bracket 126. The bottom end of casing 101 is held together by a pair of screws 123 (see also FIGURE 7), the central portions of which extend tangentially through an annular slot 122 in cylindrical portion 112, thus holding 101 on bracket 126. The lower cylindrical portion 112 of the bracket has an integral upper clamp member. Sildably mounted is a lower clamping member 116, which has a cylindrical portion 120 within the cylindrical portion 112 and a threaded bore through which a clamping screw 117 is threaded. The upper end of screw 117 extends through an opening in a wall mounted at the bottom of the cylindrical member 112, and the head 134 of the screw rests upon the top of this wall. The bottom of screw 117 carries a knob 118, which is turned to move the lower clamping member vertically to and from the upper clamping member 114. Hence, the mounting bracket may be clamped to a table or other projecting portion.
The operation of the embodiment of FIGURES 5 to 7 is similar to that of FIGURES 1 to 4. The tension on the spring is adjusted by engaging a screw driver into the screw head 132. The cams act in a manner similar to cam disc 44 and provide a counterbalance effect upon arm 104. The counterbalance effect is augmented by the friction between cams 105 and washer 124.
1. In an equipoised lamp, the combination of, a bracket and pivot structure, a casing structure mounted to be supported and pivoted upon said bracket and pivot structure, pivot means having a horizontal axis, a cam disc eccentrically pivotally mounted upon said pivot means within said casing structure, an arm having a pivot portion at one end by which it is pivotally mounted upon said pivot means and is fixed to said cam disc to turn therewith between vertical and horizontal positions, a tension coil spring having a substantially vertical axis with an upper end which terminates in a hook portion which extends around the top edge of said cam disc and rides thereon, and means attaching the other end of said spring to said casing structure, said spring and said cam disc comprising a spring counterbalance unit whereby the rotation of said cam disc from an initial rest position acts through said hook portion to increase the axial length of said spring, the relationship between said cam disc and said arm being such that said cam disc increases the length of said tension spring at such a rate as to substantially counterbalance the moment of force exerted by said arm during its swinging movement between vertical and horizontal positions.
2. Apparatus as described in claim 1 wherein said casing structure comprises two side casings which mate to form an enclosure having a slot adjacent said pivot means, and wherein said arm includes an end shell positioned within said slot and having arcuate ange means closing said slot.
3. Apparatus as described in claim 2 wherein one of said side casings has a bore, the axis of which is parallel to that of said spring means, and wherein said pivot structure comprises a pivot member having a boss positioned within said bore, stop means to limit the rotary movement of said boss within said bore, and adjustable friction means contacting the side of said boss and retaining said boss in said bore.
4. Apparatus as described in claim 2 which includes a friction disc mounted to rotate with said cam and means to adjust the friction exerted between said friction disc and said casing, and wherein said pivot means comprises a stub shaft rigidly mounted upon the inside wall of one of said side casings.
5. Apparatus as described in claim 2 which includes a second arm attached to the end of the rst arm, and a lamp and shade assembly supported upon the end of said second arm.
References Cited by the Examiner UNITED STATES PATENTS 1,634,922 7/1927 Stubblebine et al. 248-418 2,256,972 9/ 1941 Dake 248-289 2,416,910 3/1947 Crosby et al. 248-280 2,665,870 1/1954 De Wiess 248-280 FOREIGN PATENTS 1,111,289 7/1961 Germany.
CLAUDE A. LE ROY, Primary Examiner.
FRANK L. ABBOTT, Examiner.
J. PETO, Assistant Examiner.