Patents – infringement and validity – safety system used for the detection of obstructions in the path of a moving part of machinery, such as press brakes
Davies v Lazer Safe Pty Ltd  FCA 702
For those unaccustomed to industrial machinery, you would be forgiven for thinking that a press brake is the pedal to the left of the accelerator and equally for thinking that it would be interesting but generally not very helpful to know that your brake pedal is obstructed prior to using it.
But a press brake is, in fact, a device used to bend sheet and plate metal. And where the obstruction in a press brake is an appendage of the body, a safety system which detects the obstruction, and stops the machine, would be considered very useful to the owner of said appendage. And also the owner of the machine. And perhaps the manufacturer of the machine.
Returning to the case at hand, there was a plethora of safety systems in the market prior to the patented invention, which included light beams projected onto detectors that, if the beam was broken, caused the machine to stop. The claims of the patent in suit described a particular type of safety mechanism for a part of a machine that moves through a known path, with a light emitting means, a light receiving means and a processing and control means to receive “image information” from the light receiving means and thereby recognise the presence of shadows cast by obstructions and, with that information, determine the boundaries of the shadowed region and control movement of the said part of the machine.
Before your eyes glaze over, the gravamen of this case concerned the proper construction of the claim and whether, as Mr Davies asserted, the claim did not require the shape of an obstruction to be determined and did not require a comparison with a stored image. While you ponder that, you will no doubt be unsurprised to hear that the respondents’ position was that the claim required the system to determine the shape of any obstruction and compare that against stored images and thereby control the movement of the part based on the determination of identification of the shape of the obstruction. The respondents argued that they therefore did not infringe, but as a safety net asserted that, if they did, then the claims were invalid.
The respondents’ safety system first scans and then identifies the location of the moving part and then blanks segments of the resulting image representing the location of that part. This means that the shadow cast by the part would not result in the part being stopped from moving. Only if a shadow is detected in a non-blanked area, an “unknown” shadow, is movement of the part stopped. This does not involve determining the shape of an obstruction or comparing it to any stored images so as to cause the part to stop moving.
Justice McKerracher held that he preferred the evidence of the respondents’ director as to construction of the claims of the patent, since he was “representative of the skilled addressee” and the applicant’s independent expert was not. That is curious insofar as his Honour did not find that any of the terms used in the claims of the patent held anything but their ordinary meaning as opposed to a special technical meaning. Accordingly, it might be said that there was no need to prefer one witness’s construction of the claims of the patent over another.
That did not put a brake on his Honour finding that the claimed “image information” received from the light receiving means must be information used to “recognise the presence of one or more shadowed regions”. His Honour concluded that, therefore, the shape of the obstruction must be capable of being determined sufficiently to be used by the system. The word “recognised” meant that the system is not just detecting a shadowed region but “recognises, that is, compares the shadowed region detected with what is previously known – the shape of obstructions”. That construction was said by his Honour to be consistent with the body of the specification. Finally, to press the point home, his Honour concluded that it was “quite clear that the blade [moving part] cannot be an obstruction” within the meaning of the claim and the requirement that a “boundary” of the shadowed region to be determined would not occur if only an edge of an object was discerned.
His Honour accepted that the respondents’ system did not determine any shape or boundary of the obstruction as required by the claims. The respondents’ system instead uses a “relatively simple method to determine the presence of an obstruction by monitoring a list of binary values which convey the “obstructed” or “clear” state of pre-determined areas”. To sheet the point home, his Honour observed that imaging of the moving part itself was irrelevant because that was not the relevant obstruction of the claimed invention.
There was no obvious break with tradition on validity – the asserted anticipations failed to clearly identify every integer of the claimed invention and the respondents’ evidence of what constituted common general knowledge was not accepted – the director of the corporate respondent, while a skilled addressee, was too knowledgeable.