CA1113911A - Articulated-arm supporting member, especially for lamps - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE . -An articulated arm supporting structure for a lamp is disclosed, in which the combination of three arms with a couple of friction discs and a pull spring is such as to permit to place the entire arm assembly in any desired position while balancing the entire structure by the exploitation of both re-siliency and frictional forces. -

Description

Supporting arms for lamps are known, which are structurally composed by two articulated quadrilaterals which are pivotally'connected together and to a support-ing means and are equipped with a spring and frictional enga~ement member system capable of balancing the weight of the assembly irrespective of the position in which the assembly is The lamp can thus be manually displaced without any appreciable force~ to the position which is desired by the user.
These supporting members give more than satis~
factory results but their construction is expensive clue to the comparatively high number of the co~ponent parts concerned, both in the formation of the two articulated quadrilaterals and in that of all the pi~otal nodes~
and also in the spring an'd frictiohal-member balancing system.
An obJect of the present invention is to provide an articulated-arm supporting member of the'kind referred to aboveg particularly but not exclusively for lamps~
having such a structure which~ while retaining all the advantages over the conventional supporting members~ ca.n be fabricated with a minimum number of component parts and thus with a considerably lesser irst costO
To this end~ according to the invention7 it has been envisaged to provide an articulate~-arm supporting member characterized by comprising9 in combination: a supporting member proper, a couple of side arms intercon-nected and coaxially pivoted to said supporting member proper~ a third central arm of connecting rod pivoted to a crank which is rotatable coaxially with the side arms, and a fourth arm pivoted to the free end of the third zr~ and~ in addition, to the freeends of the side arms .

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FIGUKES 1, 2 and 3 are side elevational views of a supporting member incorporating the principles of this invention in two ~ifferent working positions, and FIGUR~ 4 is a view taken along the arrow ~ of FIGURE 1, partly in cross-sectional view.
With reference to the drawings, the supporting member in question comprises a supporting section 10, having a generally " U " shaped outline, -to which, by the agency of a pin 11~ are pivoted the end headers of disclike form7 12~ of a couple of side arms 13 which are extended from the U-section.
The pin 11 is partially screw-threaded at 14 at ~S either end so as to be screwably fastened ( as viewed in FIG. 4) to the complementary seat 15 of either header piece 12, and has a head 16 at the opposite end, so that its screwing-in, with the insertion of a pack of cup springs 17, permits the controlled pressure of both headers 12 against the U-section 10. Thus~ two friction surfaces S are provided for the articulation of the arms 13~ which takes place concurrently since the arms are interconnected by a transversal dowel 18 which is moved within a couple of semicircular slots 19 formed through the U-section 10. -To the pin 113 in the interior of t~e U-section lQ~ is pivoted~ in addition~ a couple of discs 20 spaced apart from each other by a bushing 21 and to which is pivoted~ through an eccentric pin 22~ a third central arm 23 inserted between the side arms 13. Obviously7 also in this case, by virtue of the clamping action provided by the pin 11~ frictional surfaces are provided~ S'~ for the ar~iculation of the centra' arm 23.
To the free end of the arm 237 by the intermediary of a pin 24~ is pivot~d a fourth arm 25~ having a U-shaped : 3-, . ..: : , `
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cross-sectional outline~ the webs of which~ by the agency oE pins 26, are pivotedg in their turn~ to the side arms 13.
To the free end of the arm 25 is fastened the member intended to be hung (not shown in order not to overcrowd -the drawing)~ more particularly a lamp, the weight of which is balanced by a spring 27 which is held taut between a pin 28 of the stirrup 10 and the pin 18 which connects the headers 12 of the arms 13 to one another, and by the functional assembly which is composed by the items 16-17 20 which cause the surfaces S and S' to become active.
FIGURE 4 of the drawin~s clearly shows that the position of the hung article ~an be varied by rotating the arm 25 about the pins 26~ that which obviously causes a rotation~ about 11~ of the discs 20 due to the action of the arm 23 and the eccentric pin 220 In practice~ the arm 23 and the pin 22 and the discs 20 compose a crank and connecting rod assembly.
During the displacements referred to aboveg it is apparent that the concurrent action of the frictional suraces S and S' of the spring 27 permits to effect smooth displacements with the stoppage of -the assembly in the stable position as desîredO
It has been proposed~ thus~ a supporting structure with articulated arms with an incorporated balancing system which~ for being embodied~ requires a minimum num ber of component parts~ more particularly for the articu-lated connection between the several arms and for embody-ing the balancing system with spring and frictional sur-faces, that which~ as is obvious~ involves a considerable advantage from an economical point o-f view.
While a possible embodiment of the invention has 4~

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been shown and described herein, it will be understood that modifications and changes can be introduced there in without departing from the scope of the invention as defined in and by the appended claims.

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Claims (5)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. An articulated-arm support device for lamps, com-prising: a support member having an upper portion formed as a pair of parallel upwardly extending walls; a pair of side arms terminating at one end with disclike heads ex-ternal with respect to said parallel walls of the support-ing member and being coaxially pivoted to said parallel walls through a traverse pin; a central arm having one end eccentrically pivoted to a pair of mutually spaced lateral discs, coaxially and pivotally mounted on said pin inter-nally to said walls of said supporting member; a further arm, pivoted to the other end of said central and side arms;
first resilient means being associated with said pin adapted to resiliently force said heads, walls and discs along the axis of said pin and to provide for frictional engagement therebetween; and second resilient means acting between said supporting member and at least one of said pivoted heads to balance the arm assembly.

2. An articulated-arm support device according to claim 1, wherein said confronting surfaces of said heads, walls, and discs are adapted to provide direct frictional engagement therebetween.

3. An articulated-arm support device according to claim 1, wherein said discs are mutually spaced apart by a bushing interposed therebetween.

4. An articulated-arm support device according to claim 1, wherein: said first resilient means is formed of compression spring means interposed between an end of said pin and one of said heads, the other end of said pin being rigidly fastened to the other head.

5. An articulated-arm support device according to claim 1, wherein: there is provided a dowel interconnecting said heads and passing through arcuate slots in said walls of the supporting member, and said second resilient means is an extension spring having one end attached to the supp-orting member and the other end attached to said dowel.