Filing early is extremely important when it comes to protecting an invention with a patent. Many applicants make the mistake of waiting until they have an ideal embodiment reduced to a high degree of precision before attempting to craft a patent application. While skillful and artful crafting of an application is paramount in the document which ultimately matures to a grant of patent, it is a mistake to presume that one should  wait to file until the invention is crafted to a state of perfection. 

The graphic above was drawn in a moleskine 3″x5″ notebook during a conversation, about an hour ago. It is a timeline showing the amount disclosed on the positive y axis, and the breadth of potentially claimable scope that corresponds to that disclosure as a venn diagram alongside the negative y axis. Apologies for any roughness, this may support an explainer video or flash movie at a later time, but I’m keeping it to a brief description for now. 

At the first time point, a provisional application ([A]) disclosing some amount of content is filed. The short black bar represents the quantity of content contained as a disclosure to the public. Below the black bar is a darkened circle showing that claims can ultimately be written as to this entire black bar. 

At the second time point, a non-provisional application is filed (B). The quantity of disclosure at this time is represented by the stacked bars , the lower bar being a repeat of the black bar shown at the first time point, with an additional white bar representing content that it discloses but which was not also disclosed in the A. Below that point is a Venn diagram showing a large circle (identical to the earlier scope circle of A), with the new content represented by a smaller circle.*

As the value to the public of a granted patent is the disclosure of matters which advance the state of technology, in order for those things to be practiced, in order to advance society, the grant only facilitates protection back to the date at which the disclosure was made to the public. Where the disclosure was made earlier, the public is presumed to benefit earlier. Patent protection extends to the scope claims that is supported by the disclosure that is truly new to the public. Presuming the disclosure contains a certain amount of such broadly stated original material, that entire scope might be claimed with the generic statement adequate to represent that disclosure. Think: “I claim: a wheel.” Therefore, 
The two-time points may be separated by no more than one year, in order for B to claim the benefit of the earlier filing date of A. 
* I have presumed that the new content is only of a narrowing character providing requisite detail to support a narrower claim (scribing a scope to trade breadth for definiteness, to increase chances of allowance of protection sufficient to support a desirable embodiment embodiment), typical of a invention being refined. If the invention was changing in character, then perhaps the circle might only overlap, as some breadth might then be possible as to matters outside of the original disclosure because they introduced matters, outside of the general matters than fewer 

Therefore, a subsequent, non-provisional, application, claiming the broad notion would then be entitled to that entire notion of “the wheel” (to the degree disclosed).

Unfortunately, it’s fair to say that inventors tend to know that they will be narrowing significantly, on their way to patentability. This is why the additional disclosure is necessary. The details which would support the protectable invention simply wouldn’t likely to be known by the inventor at the time of the original disclosure, as a routine matter. When those details are determined, those matters legitimately “invented,” sufficient that their disclosure would allow a person having ordinary skill in the art to practice the invention (according to those details), then they are ready to be put in application, such that they can be claimed. 

The second time point, at which the non-provisional was filed, includes both the original disclosure and the second disclosure, so the claims can still be written as broadly as in the original disclosure (“the wheel”), while also allowing protection as to the narrower matters.such as “I claim: the wheel, where in the wheel comprises a circumferential rim, a central hub, and a plurality of spokes extending radially from the hub to the rim.” 

If the inventor had waited to file until composing a non-provisional disclosing identically to B, but believing he was entitled only to the new matters, The public would be educated as to all disclosed matters, but claims might be overly focused solely upon those new matters, and his claims might reflect it, obtaining relatively small protection. That would be the smaller circle in the Venn diagram at the time of B. 

Had he truly been entitled to the broader protection, the public would now know how to make everything understood to be a wheel that lacked the specifications of the hub and spokes and a rim, essentially the entire dark circle at the second time point, less the smaller circle. That’s a lot of time to make and sell and practice inventions, cutting deeply into the benefit the inventor might have been able tosecure for himself. 

If claims were directed in B, to the broadest matters, then protection might have been available to protect “the wheel,”, but without having disclosed at the time of day, protection would’ve only been enforceable back to the date of B, potentially giving up the right to enforce against infringements of practices reasonably within the meaning of “the wheel” which occurred between the time at which A could have been filed. That’s a period of up to 12 months! 
Where this all becomes relevant, is that in order to actually develop the invention, an inventor will have to promote and share disclosures of the invention to other parties. As a typical matter, this should be done as early as possible, but where these disclosures are made before a date of filing, The inventor risks making disclosures that antedate his application, if they are more than one year ahead of the time of filing, and even succeeding on the broader notions risks the chance of infringements occurring during that period, at which point the infringing entities, having benefited from the disclosure and acting outside of a document, get to play in the market, until the inventors able to succeed on his grant of patent. 

Taking that risk is foolhardy. The point of a patinas to exclude others, and you can’t do that if you are avoiding asking for that protection as soon as possible.