AU650300B2 - Adjustable support arm assembly - Google Patents

Description

i1 Regulation 3.2

AUSTRALIA

Patents Act 1952 COMPLETE SPECIFICATION FOR A STANDARD PATENT

(ORIGINAL)

650 300 Name of Applicant: Actual Inventor(s): Address for Service: Invention Title: DUKESEA PTY. LTD.

DAVIES COLLISON CAVE, Patent Attorneys, 1 Little Collins Street, Melbourne, 3000.

Adjustable Support Arm Assembly Details of Associated Provisional Application: No.: PK3592/90 filed 28 November, 1990 The following statement is a full description of this invention, including the best method of performing it known to me/us: -2- ADJUSTABLE SUPPORT ARM ASSEMBLY The present invention relates to an adjustable support arm assembly and more particularly to an adjustable support arm assembly for carrying a light unit so as to permit large variation in the placement of the light unit.

Adjustable arm assemblies for supporting a light unit in a variable position conventionally comprise a number of parallelogram linkages each subject to a spring bias which balances the linkage when moved into a selected position. Conventionally, a separate spring is associated with each parallelogram linkage.

An object of the invention is to provide a simplified construcrt'::iW s,balanced arm linkage.

According to the present invention, there is provided an adjustable support arm assembly comprising a lower parallelogram linkage having two parallel arms pivotally connected to a base for swinging movement in a substantially vertical plane, the two parallel arms of the lower parallelogram linkage having upper ends pivotally connected to support means, an upper parallelogram linkage having two parallel arms pivotally connected at their inner ends to the support means for swinging 911126,csspe.003,planetspe,2 -3movement in a substantially vertical plane and adapted to carry a load, such as a light unit at their outer ends, and a single balancing spring extending between the base and an arm of the upper parallelogram linkage at a position rearwards of the axis of the pivotal connection between that arm and the support means whereby the single spring acts to balance both parallelogram linkages.

An embodiment of the invention will now be described by way of example only with reference to t e accompanying drawings in which:- Figure 1 shows in detail the two parallelogram linkages of a support arm assembly in accordance -Ath a preferred embodiment of the invention; Figure 2 shows schematically the range of movements possible with the arm; Figure 3 is a schematic side elevation showing a modified arm assembly incorporating a finger guard; Figure 4 is a detailed view showing the mounting of the finger guard at the forward end of the upper parallelogram linkage; and Figure 5 is a section through the upper parallelogram linkage.

As shown in the accompanying drawings an adjustable support arm assembly comprises a base 2 having a downwardly directed shaft 4 for mounting in a suitable support to permit rotation of the arm assembly through 360 about a vertical axis defined by the shaft 4. The base 2 supports a lower parallelogram linkage 6 comprising two parallel arms 8, 10. The arms 8, are pivoted to the base 2 at pivot points 12, 14. The forward arm 8 is of channel section and houses a spring 16, the lower end of which is connected by a link 18 to the base 2 at a position displaced from the two pivots 12, 14. As will subsequently be described, the other end of the spring 16 is conlected by means of a link to an arm of an upper parallelogram linkage and is so arranged as to balance both parallelogram linkages and which, as is apparent, each swing in a vertical plane.

911126,csspe.003,planetspe,3 The upper end of each of the two arms 8, 10 is pivotally mounted by pivots carried by a suitable structure 22 which, as shown, is in the form of two spaced circular plates which conceal the ends of the arms. The plates also support the inner ends of two parallel arms 24, 26 forming the upper parallelogram linkage 20. The pivot points for the upper arms are shown at 28 and 30, the lower pivot 30 being included on an axis which passes through the upper pivots of the lower arms 8, 10. The spring 16 within the forward of the two lower arms is connected at its upper end by a link 32 to the lower arm 24 of the upper parallelogram linkage 20 at a position rearwardly of the pivot whereby the spring will have the effect of balancing the upper parallelogram linkage 20 and also the lower parallelogram linkage 6 thus obviating the need for separate springs for each of the two linkages. The forward ends of the arms 24, 26 of the upper parallelogram linkage are attached to a suitable structure 34 by pivots 36, 38. As shown the structure 34 is defined by two parallel cover plates 34a which act to conceal the forward ends of the arms.

The cover plates 34a also act to support the light unit 40 which may be pivotally attached to the cover plates 34a by means of a forwardly-extending arm 42 mounted on the pivot 38 so that the arm 42 and light unit 40 supported thereby can be held in a selected orientation du 'ng adjustment of the two parallelogram linkages. The mounting for the light unit 40 on the arm 42 may be such as to permit the light unit to be swivelled about a vertical axis at the forward end of the arm 42 as shown schematically in Figure 2.

In a modification shown in Figures 3 to 5, a finger guard is associated with the upper parallelogram linkage 20 to prevent the fingers of a user from being trapped between the arms 24, 26 during adjustment of the upper parallelogram linkage 20. The finger guard comprises opposed plates 46 on opposite sides of the gap between the arms 24, 26, and of a width greater than the maximum width of the gap so that the plates 46 overlap the sides of the arms, 24, 26 and close the gap along the length of the arns at all positions of the upper parallelogram linkage 20. The plates 46 are pivoted at their forward 911126,csspe.003,)Ianetspe,4 ends to the cover plates 34a by means of a pivot 48 midway between the pivots 36, 38. The rear ends of the plates 46 are similarly connected to the support structure 22 midway between the pivot points 28, 30. Preferably, spacers carried by the two plates 46 extend through the gap at positions along the length of the plates 46 in order to maintain the plates 46 in parallel relation clear of the outer surfaces of the arms 24, 26. The spacers 50 also act as stops to limit the adjustment of the upper parallelogram linkage 20 in an upwards and downwards direction. Tf required, a similar guard may also be associated with the arms of the lower parallelogram linkage.

The embodiments have been described by way of example only and modifications are possible within the scope of the invention.

911126,csspe.003,planespe,5

Claims (4)

1. An adjustable support arm assembly comprising a lower parallelogram linkage having two parallel arms pivotally connected to a base for swinging movement in a substantially vertical plane, the two parallel arms of the lower parallelogram linkage having upper ends pivotally connected to support means, an upper parallelogram linkage having two parallel arms pivotally connected at their inner ends to the support means for swinging movement in a substantially vertical plane and adapted to carry a load, such as a light unit at their outer ends, and a single balancing spring extending between the base and an arm of the upper parallelogram linkage at a position rearwards of the axis of the pivotal connection between that arm and the support means whereby the single spring acts to balance both parallelogram linkages.

2. A support arm assembly according to claim 1, wherein at least one of the linkages includes a guard operative to prevent insertion of the fingers between the respective arms of the linkage during swinging movement of the linkage.

3. A support arm assembly according to claim 2, wherein the guard comprises opposed plates extending along opposite sides of the arms and spanning a. gap defined between the arms, said plates being mounted to swing with the arms during movement of the respective linkage.

4. A support arm assembly according to claim 3, wherein the guard further comprises spacer means extending through the gap between the opposed plates. A support arm assembly substantially as hereinbefore described with reference to the accompanying drawings. DATED this 14th day of April, 1994. DUKESEA PTY.LTD. By its Patent Attorneys: DAVIES COLLISON CAVE 940413,p:\oper\rs dukesea.spe,6 ABSTRACT An adjustable support arm assembly, for example for a light unit, comprises upper and lower interconnected parallelogram linkages (20, 6) pivotal in vertical plane. A single balancing spring (16) extends between a base of the support and the upper linkage (20) and serves to balance both the upper and the lower linkage. 911126,csspe.003,planetspe,8