(This question is closely related to What practical requirements are there for unity of an invention with multiple independent claims?, in which I ask for details about the "unity" of an invention when I can break down the invention into several independent claims.)

Let's assume there is a patent on a machine that "dries hair with hot air", and I have five other ideas how to dry hair (ice cubes, friction, whatever). I would like to avoid having to file five patents.

Obviously, I cannot claim a machine that "dries hair" any more.

When restricting myself to one independent claim (e.g., at the EPO), I would like to have a claim about a machine that "dries hair by other means than hot air"? Is that possible at all?

  • Could you make that two questions? I don't think there's reasonable overlap between the two. ("means other than" / negative features and unity) you can then provide links between them.
    – user18033
    Commented Jan 22, 2018 at 15:11
  • @DonQuiKong thanks for the suggestion, I'll try to carve out the unity issue from this question.
    – bers
    Commented Jan 22, 2018 at 15:22

1 Answer 1


The term "other than" is, by nature, rather vague. The primary purpose of patents is to teach the world how to implement your "new, useful and non-obvious" contribution to the state of the art. Therefore, unless you have also defined what are the specific "new and non-obvious" alternatives you are claiming, you will have failed to "enable" others with adequate teaching and your claim would not be valid, even if accidentally granted.

Taken to absurdity, you could not claim, "A device for drying food, where such device is unlike any other." You must specify HOW it is unlike anything ever used in public or disclosed in any publication, using terms that contribute beyond the "prior art".

  • Thanks, I can follow that. What if I claimed a machine that "dries hair by other means than hot air, e.g., with ice cubes (done in such and such way), or friction (dito)", in a way that would enabled others sufficiently? Could this become a valid claim in any way?
    – bers
    Commented Jan 22, 2018 at 19:59

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