Related to a previous question patent specification level of detail

I want to file two patent applications for two inventions that use some common underlying technologies (the same ones I'm talking about in the related question).

Should I describe these underlying technologies in both applications? These would implicate that some drawings and descriptions would be repeated in both applications.

2 Answers 2


Ultimately, this is determined by 1) ensuring your description describes the invention sufficiently for a skilled person to perform it 2) your claims are supported by the description 3) for the US, you include the best mode known to you

So it depends on just how common the technologies are, and how you are using them. How much would the skilled person (in the field of your invention) know about them? If they're very well known, so everyone in the industry is familiar with them, you don't have to say much at all. If they may not be familiar (maybe it's a different field), you can find a previous patent/application that describes the technology in detail and quote the patent number (or indeed any reference, but patents are convenient). If you're relying on particular aspects of the technology, or a particular variation of the technology, and especially if you'll be including elements of the technology in the claims, it's better to spell it out in full.

Read some existing patents to get a feel for the level of detail.

BUT! You know the phrase 'if in doubt, leave it out'? Patents are very much 'if in doubt, stick it in'


There is nothing wrong with two applications containing common material. Usually underlying technology is explained in the context of its use in that particular invention rather than in isolation.

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