Patents

Case Note: General Clutch Corporation v Sbriggs Pty Ltd

Jane Lambert

Oct 1998
This article formerly appeared on the Lancaster Buildings  website

The patent in suite was for improvements in spring clutches used in winding and fastening window blinds. The invention provided for a spring clutch in which torque can be transmitted to the load in graduated steps to allow for a slower acceleration of the load than happens when the maximum rated torque is applied suddenly to the load. Its distinguishing features were that it used more than one spring to effect connection between input and output elements and the positioning of the control surfaces within the clutch were such that the several springs could be made to operate at different times. Claim 1 of the patent commenced with the words:

"A spring clutch comprising a first shaft, a coaxially mounted second shaft, and at least first and second 10 springs, ………."

The defendant, which manufactured various clutches with three shafts, argued that its products did not infringe the patent because the participle "comprising" restricted the claim to a clutch with two shafts and nothing more. It contended that any other construction strained the ordinary meaning of the word "comprising" and invalidated the patent on the grounds of failure to define the invention clearly and succinctly and lack of fair basis.
Meaning of "Comprising"

After consulting various British and Australian dictionaries as well as authorities on modern English usage Lindgren J held that "comprising" meant "consisting of, made up of, composed of, or constituted by" the following parts as essential elements of the clutch. His judgment was fortified by a number of decisions including the following words of Sir John Bennett of our old Palatinate Court in Chain Bar Mill v Wild (1939) 56 RPC 446:

"One would, I think, most naturally expect the word `comprising' to be followed by several items making up the whole."

His Honour concluded that the plaintiff claimed a device which possessed four functional elements and consisted of the integers claimed in claim 1, and nothing more. As the defendant's clutches required three shafts to function as a clutch, it was apparent that they did not infringe the plaintiff's patent. The defendant had also pleaded that the patent was invalid because it did not specify the invention with sufficient clarity and that the claims were not fairly based. Having found no infringement, the judge did not feel the need to address those points.

 

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