US2409075A - Extensible stand - Google Patents

Description

Oct. 8, 1946. A. M. sTARcK EXTENSIBLE STAND Filed Nov. 18, 1944 R o T N E V m ORNEYS Patented Oct. 8, 1946 UNITED. STATES PATENT OFFICE Arthur M. Starck, Stamford, Conn.

Application November 18, 1944, Serial No. 564,110

2 Claims. (Cl. 248-161) This invention relates to adjustable stands and more particularly to stands for lamps, microphones, music supports and the like.

Stands for lamps and the like have been made vertically adjustable by various constructions which usually employ clamping screws that have the disadvantage of requiring loosening and tightening each timeit is desired to change the height adjustment. Screws are furthermore difficult to operate and detract from the appearance of the stand. The unbalanced weight of the vertically movable part of a stand causes considerable eifort to be required to raise it and also makes it difiicult to obtain accurate adjustment.

Principal objects of the present invention are to provide an improved stand for'lamps and the like which is easily adjustable in height, which needs only to be pushed down or up to adjust its height, and which will remain at the adjusted height without the use of clamping screws. Other objects of the invention are to provide an adjustable stand of the type in which the upper portion is vertically movable with respect to the lower portion; in which the Weight of the upper portion is counterbalanced; in which the counterbalancing device is completely enclosed within telescoping tubular members of the.stand; and in which a spring is employed as a counterbalancing element in such a manner that the variation in force exerted by the spring may be compensated.

Other objects of the invention will in part be obvious and will in part become apparent from the following detailed description of one embodiment thereof, in which:

Figure l is an elevational view of an exemplary lamp stand according to the invention, with parts broken away to show the interior construction;

Figure 2 is a view of a section taken on the line 2-2 of Figure 1 showing the upper anchor of the counterbalance device;

Figure 3 is a view of a section taken on the line 33 of Figure 1 showing the counterbalance and means to prevent relative rotation between telescoping members;

Figure 4 is a view of a section taken on the line 44 of Figure 1 showing the guide between the spiral ribbon and the spring; and

Figure 5 is a view of a section taken on the line 5-5 of Figure 1 showing the lower anchor of the counterbalance device.

As a preferred example the stand device of the present invention is incorporated in a floor lamp or bridge lamp. The device to be supported is 2 embodied in a lamp in secured in a customary manner at the endof a cross arm ll of a post 12 which is mounted on top of an upper telescope tube I3. The tube l3 telescopes within a lower tube M which has an inner diameter onlyslightly greater than the external diameter of the tube [3. The tube 14 is vertically supported by suitable means such as a base 15. It is desirable to provide means for preventing relative rotation between the tubes [3 and I4 and for such purpose a spline or longitudinal ridge [6 is formed in the wall of the tube l3 and a corresponding cooperating groove is formed in the tube 4,

The function of the counterbalance deviceis to stabilize the weight of the movable part of the stand, that is, the tube l3 and the parts supported thereon. The counterbalance device is disposed entirely within the tubes 13 and i4, and it includes a helical torsion spring I! having its lowerend secured by a bolt l8 to the lower end of the tube [4. A spacer I9 is disposed between the Wall of the tube l4 and the spring [1. The spring I! extends to a point near the upper end of the tube l4 and has secured to its upper end a cap piece 20 by engagement of the upper coils of the spring in threads 2| formed in the cylindrical part of the cap. In the upper portion of cap 20 there is provided a slot-shaped opening 23 the longer dimension of which is substantially equal to the inner diameter of the cylindrical part of the cap piece.

Through the slot 23 extends an auger-like or ribbon-like spiral member 24 such as may be formed by twisting a rectangular flat strip of metal. The twist or pitch of the spiral however, is not uniform for reasons hereinafter described. The length of the spiral member 24 is slightly greater than the length of the spring l1 and it extends upward into the tube I3 to which it is anchored at its upper end. A stud 25 is secured to the inside wall of the tube [3 and the end of the stud is threaded to receive a nut 26 which clamps the upper end of the member 24 to the stud. When the member 24 is forced into the spring H, the cap 20 is rotated and such rotation twists the spring I'I. When the member 24 and tube l3 are stationary, the tension of the spring I! reacts on the helical elements or surfaces of the member 24 and tends to force it upwardly. The pitch of the member 24 and the strength of the spring [1 are selected so that the upward force on the member 24 is sufficient to balance the weight of the tube I3 and elements carried thereby.

When a torsion spring is twisted, its tension Thus when the cap 2011s in the upper region of the member 24; the coarse pitch in conjunction with the greater tension of the spring l'l will pro; vide an upward thrust in member 24 which is about the same as the upward thrust which is obtained by the weaker tension in conjunction with the finer pitch when the cap Zlldsizithelower region of the member 24. I

While not essential, it is' found'advantageous to enclose the spring I! within a guide tube. 23 in which the cap 20 and spring I! are rotatable and which is secured between the spacer l9 and the endof the spring H by bolt [8. A limited degree 7 of adjustment of the counterbalance device according tothe weight to be supported is obtainable by preset ns h i it al te s on of the spring ll as by givingthe lower end the requisite number of turns-before securing it by the bolt I8 7 It will be seen that the lamp may bemoved up and down with equal. ease, that such movement will be smooth, and that only a minor amountof friction between the movable and stationary parts sufiices to hold the lamp firmly in y a u t pos tion.

nder toq j ha e clo u described above, various, modifications may be made without affecting the. principle of theinvention; furtherthat theinvention is not to be n dered s l mi d t h e m ntwh h 4 is described herein only for purposes of illustration, but solely by the terms of the appended claims.

What is claimed is:

1. In a telescoping stand having stationary and movable relatively non-rotatable portions, a device for counterbalancing the weight of the movable portion, said device comprising a helical compression spring non-rotatably, secured at one endto' the stationary portion, a cap member rigidly secured to the other end of said spring, and an elongated member non-rotatably secured at one end to the movable portion and provided with a helical element extending through and threadedly engaging said cap member to torsion said spring, aid cap member reacting under the torsional force of said spring to provide a vertical force'adapted to support the weight of said movable portion.

2; In a telescoping stand having stationary and movable relativelyv non-rotatable portions, a. device for counterbalancing the weight of the movable portion, said device comprising a helical compression spring non-rotatably secured at one end to the stationary. portion, a cap member rigidly secured to theother end of said spring, and an elongated member non-rotatably secured at one end to the movable portion and provided with a helical element extending through and threadedly engaging said cap, member to torsionsaid spring, said cap member reacting under the torsional force of said spring to provide a vertical force adapted to support the weight of said movable portion, said element having a variablepitch, said pitch being greatest at the end farthest removed from the spring and least at the end which enters the spring.

ARTHUR; M. STARCK.

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