Patents can be another important source of technical information on calculators. By law, the patent disclosure must describe the invention with sufficient specificity "as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected" to be able to make use of the claimed invention without undue experimentation. 35 U.S.C. § 112 (2004); MPEP § 2106(V)(B) (2004). It is important to note that this disclosure requirement is measured at the time the invention was made. 35 U.S.C. § 103(a) (2004); MPEP § 2106(VI) (2004).
As a practical matter to the calculator collector, the patent disclosure will contain a wealth of information about a calculator design. The disclosure may contain schematics, software listings, flow charts, and other useful information. Where appropriate, the patent may even describe the internal design of a chip. However, the patent may or may not describe a product which was actually marketed, or may only describe an early version of the product. Further, if the disclosure relates to a new feature of a calculator, the disclosure may not describe the unrelated aspects of the calculator (e.g. if the disclosure relates to a software feature, there may not be much of a discussion about the hardware).
The patents listed below are by no means an exhaustive list of calculator related patents. It only contains what I have subjectively found to be interesting in my non-exhaustive non-systematic search for calculator patents. I've restricted my searching to digital calculating devices - devices that operate in discrete states - and not analog calculating devices like slide rules. I also made the arbitrary decision that the calculating device had to be intended primarily for an individual user, and not a shared device like a centralized data processing machine. I also included are a few interesting calculator accessory patents.
My web site, Calculator Technical Information, is not affiliated with or endorsed by the USPTO. No copyright claim is made to original U.S. Government works.
Below, I've categorized 1089 calculator related patents I've found into several categories. Note that patents are only listed in one category.
Calculator Patents By Major Electronic Calculator Manufacturers. The following tables list patents held by some of the major players in the growth of the electronic calculator.
Early Calculator Patents. The following tables list mechanical and early calculator patents.
Other Calculator Related Patents. The following tables list patents in several other calculators that don't fall conveniently into any of the above categories.
Descriptions of fields in the tables.
The U.S. Patent No. field contains the number assigned to the patent by the USPTO. A Patent number beginning with "RE" is a reissue patent. A patent number beginning with "H" is a Statutory Invention Registration (SIR). An SIR really isn't a patent, but serves the defensive purposes of a patent.
The Assignee field contains the name of the persons or entity the patent was assigned to when issued. It is not updated to reflect subsequent assignments.
The File Date field contains the date the patent was filed with the Patent Office. Where the application is derived from a prior application, this field contains the date of the original application. Where the original application was with a foreign patent office, this field contains that filing date.
The Issue Date field contains the date the patent was granted.
The Product field identifies a specific product incorporating that patent if one could be determined.
The Title field contains the title as contained in the patent. Some titles are not terribly discriptive.
The Comments field is where I have tried to briefly explain the significance of the patent, or what makes it interesting.
Last updated November 5, 2006.