As mentioned in “What Is A Patent”, a development must be novel, useful and non-obvious to persons skilled or knowledgeable in the applicable technology or art.
To comply with the requirement that the development be novel, the invention must not have been known or used by others in the U.S. or patented or described in a printed publication anywhere in the World prior to the inventor/applicant’s date of invention. In addition, in order to avoid the one year “statutory bar,” the patent application must be filed within one year of the (i) first public use of the invention, (ii) the first sale or offer of sale of the invention in the U.S. or (iii) or the first published description of the invention anywhere in the world. Note that publication can be the passing out of copies of a presentation (or copies of the overhead slides used in this presentation) to a gathering of a substantial number of people familiar with the subject matter or technology of the invention, e.g. such as an industry trade group. What is important is that in certain cases, the publication baring patentability or starting the one year statutory bar, need only involve a small number of people. Similarly, actions that constitute a first public use or offer of sale can also events that may seem otherwise inconsequential to the non patent professional.
The non-obvious requirement is often stated that the development must not be anticipated by the existing technology. If an airplane comprising a wooden framework covered with cloth is already known, merely substituting an alternate type of wood will not constitute a patentable invention. Further a substitution of other materials may not constitute a patentable invention if the results achieved do not differ from the results that would be predicted by a person skilled in this technology.
The useful or “utility” requirement is met by showing that the invention has a functional purpose and is not merely ornamental. The use or utility requirement may be met by showing that the invention is humorous.
Note that this area of patent law is much more complex than this very brief summary may indicate. Consultation with a patent professional is highly recommended.