We are just about ready to file for our PPA, should our drawings contain exact measurements? The reason I am asking is that some told me that you should make your measurements a "range", i.e. 3/16 to 5/16 inches in width, when your planned width is 1/4 inch. Whereas, you prevent someone from altering a measurement and being able to steal your patent, by a simple alteration. Sounds odd to me, but I wouldn't want to loose my invention over something like that issue.
Should the drawings contain measurements?
No. Your drawings are there to show the nature of the invention, not to show exactly how it might be put into production. The particular dimensions are almost always irrelevant, and will not assist you in the drawings.
The only situation in which it might be useful to include dimensions in the drawings is where a precise size is essential (such that any deviation from the size would cause the invention not to work). However, this is so rare that I can't even think of an example.
Should the description contain measurements?
The description can (and probably should) describe a size for any physical device. However, this should be described as a preference (such as "in some embodiments, this can be about 2.5mm to about 3.5mm in length"). You wouldn't generally want to limit yourself to a particular size (such as "this must be 3mm long"), since that may restrict the scope of your protection to that particular size.
Such a measurement is typically also described as a range, and using "about" or "approximately". This further highlights that the size itself is only a guide, and is not an essential feature of your invention. It also provides more flexibility for basis for amendments in stricter jurisdictions (like Europe).
Measurements should be in metric (per MPEP § 608.01(IV)).
The drawings are supposed to be schematics, though they (rarely) contain exact numbers and (even more rarely) this can make sense if the exact number is essential for the invention.
Why you should always use (nested) ranges instead of simple one-number measurements:
I'll try to illustrate this with an example that is loosely based on a real case (which I may not disclose).
Let's assume a universe where pillows are always fully stuffed with feathers, to the amount that no more feathers fit in. From there on you invented a (novel and ivnentive) improvement: stuffing only a few % of the possible volume of feathers into the pillow, making it way more comfortable and less prone to bursting.
You go out and patent this magnificient invention. Your claim is as follows:
- A pillow with less than 99.9999% of the maximum volume filled with feathers.
Your description fits this. So you have a claim that covers basically every possible variation of your invention. But ...
It turns out, due to production errors you have been producing pillows with only 99,95% of the max. vol. filled with feathers for years. You now have effectively destroyed your patent claim, as 99,95% falls under the scope of the protection you are seeking, but is already known and does not even have the advantages you claimed it has in the description (not bursting, comfortable, cheap). This patent will then not be granted - or invalidated when somebody uses this against you.
What did you do wrong?
It is quite reasonable to see that writing "exatly 50% of the volume filled with feathers" would basically be a nonsense claim, so using a range like in the example was a good idea. But you didn't used a nested range. You should have written (at least in the description):
A pillow stuffed with less than 99.9999% of the max volume of feathers, preferably less than 95% more preferably between 30 and 95% and especially preferred between 50 and 60%.
What would have happened in this case?
You could use your fallback position of less than 95% and get that patented.
Now lets assume somebody has been using (selling) empty pillow cases without feathers as pillows and you didn't notice in your prior art search. That means "less than 95%" is gone to (0% is less than 95%, less than 95% is therefore known from the prior art). But there still is the 30% to 05% claim. Which will remain after the proceedings.
Couldn't I just take "less than 90%" out of "less than 99.9999%" as 90 is less than 99.9999?
No. (Im honestly not 100% sure about the US, but for Europe this is a 100% no, you can't and for the US its around 95% certainty)