I have a design patent on an ergonomic support on a power tool. When the patent was issued, the design consisted of two discrete parts assembled with a fastener. I've now improved the design so that it can be molded as a single part. The shape, function, dimensions, etc. have not changed - just the fact that it's now a one piece part. I'd like to add the new design to the existing patent so that I'm covered. Is there some mechanism by which one can update their patent? My attorney advised me that submitting a new design patent would be futile, as the existing one would be considered prior art. I can't believe that there's not some method to show an improved design. Any thoughts?
You can indeed patent improvements (not by "adding" to a prior patent but rather by filing a new application).
But the problem with an improvement is whether the patent office will view the improvement as something that someone skilled in that field would obviously do. And your original patent will count as what someone skilled in the field would use as their background knowledge base, and then build upon.
So, imagine yourself today as the guy skilled in the field - you didn't necessarily think about doing it as a single IM part back then, but today as you stand there looking at your "old" (publicly known) two-part version, would it be obvious (say, for reasons of more efficient manufacturing) to the guy skilled in the field to go ahead and make the one-mold version?
I can't really speak to power tool accessories, but in the fields I've worked, trying to patent the "it's more efficient" version of something has been fairly difficult because the patent office always views efficiency improvements as something the skilled person always strives after in any case. But where you can show there was some tough impediment in gettng from point A to point B, it's still possible to argue your case.