The Basics
What happens if the invention described in an application is not quite the same as anything ever described before, but is just so obvious that it doesn't seem to warrant a patent?

The PTO has thought through situations like these and as a remedy, they established 35 U.S.C. 103. This statute relates to the obviousness of the subject matter. There are times when the subject matter is obvious to anyone and everyone because the inventor merely combined two well known inventions together.

In other instances it is only obvious to people in that field with what is called ,"ordinary skill in the art". The PTO uses this definition to determine whether an invention is obvious.

A few factors to consider in determining the level of ordinary skill in the art required for practicing the subject matter include the educational level of the inventor, the type of problems encountered in the art, and the educational level of the active workers in the field.

Either way, if it is an obvious invention, the PTO will stamp it as rejected.  

In order for an invention to be considered obvious, there are a few basic criteria that must be met.

The first is there must be some suggestion or motivation in the references or in the knowledge available to the public to modify the reference or to combine the referenced teachings. What we mean by this is there must be a "hint" to combine the previous inventions.

Second, there must be a reasonable expectation of success when combining the previous inventions together.

Lastly, the references must teach or suggest each and every claim present in the new application.

It should be emphasized that a rejection under 35 U.S.C. 103 will not be made in instances where new and unexpected results are produced. Obviously, it's not obvious if a new or an unexpected result occurs.

The details
When dealing with 35 U.S.C. 103, the obviousness factor is only considered during the time period the previous inventions were made. Therefore, if advances in technology make it possible to combine the older references when they previously could not be combined, the invention may be considered nonobvious. In addition, a suggestion to combine the references does not need to be for the same purpose the applicant discloses in the application, the suggestion merely needs to have been made.  

There are many factors the PTO will consider obvious. For example, aesthetic design changes in utility patents are too obvious to warrant a patent. Aesthetic changes are any change that does not result in an alteration of the mechanical function of the subject matter. In addition, simply eliminating a step or an element that results in the elimination of that particular function will also be considered obvious.

According to the PTO, automating a manual activity is also considered obvious. So is making changes to the size, shape or the sequence of adding in ingredients in a process patent application. Making a stationary object portable is also too obvious to warrant a patent. Lastly, if a claimed range overlaps or lies inside the ranges disclosed by the prior art, it too will be considered obvious.

An example is a prior art patent for smelting lead that states the ideal temperature for heating lead is between 400-500oF. A new patent application stating the ideal temperature for smelting lead is between 450-500oF will receive a rejection under 35 U.S.C. 103 by the PTO. This is obvious because the claimed range for the new application lies inside the range disclosed in the prior art patent.