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US 4,494,177 AGranted
Articulated task lamp
AssigneePlan Hold Corporation
InventorCharles Matthews
Life of this patent
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AssigneePlan Hold Corporation
InventorCharles Matthews
Estimating the term…
An articulated task lamp for exemplary use as a counterbalanced drafting table lamp including pivotally interconnected base assembly, lower support arm, upper support arm, and lamp head, and counterbalance linkage operable within said lower support arm and base assembly and provided a novel connection to the upper support arm. The counterbalance linkage includes a torsion counterbalance spring in the base assembly having a force transmitting connection to a link member which is pivotally interconnected to a compensating link pivotally mounted intermediate its ends to the base assembly, the other end of said compensating link being pivotally connected to an elongated link member carried and operable within the lower support arm and having its other end pivotally connected to a crank member enclosed within a mid joint means providing a pivotal connection and force transmitting connection between the upper and lower support arms. The counterbalancing forces permit movement of the lamp head to any selected position over a drawing board surface and retain the lamp head in such selected position to provide desired illumination of a surface area of the drafting board. A joint structure for interconnecting adjacent ends of support arms in which the joint structure includes a cylindrical bearing and interconnection with cup shaped members carried by adjacent ends of the support arms for transmitting selected forces through the joint structure to effect counterbalancing of the lamp head.
Counterbalanced support means for a drafting table lamp in which a base means is provided with a lower base portion adapted to be clamped to a drafting table and with an upper base portion pivoted on the lower base portion about first and second axes, counterbalance means in the upper base portion including a crank member pivoted about a third axis transverse to one of the first and second torsion axes, a torsion spring means biasing said crank member, a thrust link member connected to one end of the crank member, a lower tubular support arm pivotally mounted on the upper base portion about a fourth axis, and an upper support arm pivotally connected about a fifth axis to the lower support arm and carrying a lamp provided with a pivotal connection to the upper support arm, comprising in combination:
Counterbalance support means for a lamp in which a base means is provided with counterbalance means, a lower arm is pivoted to said base means, and an upper arm carries the said lamp at the outer end of the upper arm;
Dependencies are inferred from the claim text.