The problem is that the patent at issue contains many very widely drafted claims and mean-plus-functions. The only point we can rely on is that the patent and its prosecution history shows that:
The original claim -- comprises of ....; and at least 3 legs
Rejected because of a prior art with 4 legs
They changed it to two claims: one with 3 legs and one with a leg means.
Then it was allowed!!
My questions are:
(i) can I now get a patent exactly the same as the patent at issue but with 5 legs??
(ii) if I don't have a patent and create something with 5 legs, would it be an infringement of the patent at issue??
Thank you, all the smart people here!!
(i) again, if your 5-legged beastie is more than an insubstantial difference which is indeed (as you mentioned initially, anyway) not an obvious improvement in view of the prior art (known patent w/ 3 and art cited against that patent w/ 4 legs), then it should be patentable at least in view of those 2 docs. Since our model seems to be office furniture, though, I will say that knowing of 3- and 4-legged beasties makes me give the fish eye to the non-obviousness of the 5-legged beastie unless the 5-legged beastie was formerly impossible without some new way of doing it that you've come up with... ...in which case you might want to patent that (new method) also/instead.
(ii) sounds like you're getting closer to what JimIvey mentioned, although by pros.history estoppel rather than explicitly in the claims. That is, the patentee may have limited itself to a "not more than" situation based on arguments and amendments in view of the art. But I wouldn't want to opine further without explicit info (and don't want to see it) except to say that this is the point where I usually seek opinion of patent counsel.
The M+F type claiming in the other independent claim may be very narrow also, but this itself is another intensely fact-dependent review. M+F claims formerly were given fairly broad coverage but now are essentially limited to those means taught in the spec to perform said function and the obvious equivalents to those means. Not to mention, at least as you've described it ("leg means" v. "means for supporting said substantially horizontal surface", for example), it may not really be an M+F claim from a legal standpoint but really just recite the same as "a leg". Here's a fairly recent thread on M+F claims
http://www.intelproplaw.com/ip_forum/index.php/topic,10519.0.htmlIf you're no longer dealing with hypotheticals (HOW'd the test go?!), I'd get the info to patent counsel.