Diamond v. Diehr, 450 U.S. 175 (1981), was a United States Supreme Court decision which held that controlling the execution of a physical process, by running a computer program did not preclude patentability of the invention as a whole. The high court reiterated its earlier holdings that mathematical formulas in the abstract could not be patented, but it held that the mere presence of a software element did not make an otherwise patent-eligible machine or process patent ineligible. Diehr was the third member of a trilogy of Supreme Court decisions on the patent-eligibility of computer software related inventions.

Background

The problem and its solution

The patent application in question US05/602,463 was filed on behalf of inventors Diehr and Lutton in 1975. The application claimed a "[process] for molding raw, uncured synthetic rubber into cured precision products." The process of curing synthetic rubber depends on a number of factors including time, temperature and thickness of the mold. Using the Arrhenius equation

<blockquote>

<math> k = A e^</math><br>

which may be restated as ln(v) = CZ + x

</blockquote>

it is possible to calculate when to open the press and to remove the cured, molded rubber. The problem was that there was, at the time the invention was made, no disclosed way to obtain an accurate measure of the temperature without opening the press. In the traditional method the temperature of the mold press, which was apparently set at a fixed temperature and was controlled by thermostat, fluctuated due to the opening and closing of the press.

The invention solved this problem by using embedded thermocouples to constantly check the temperature, and then feeding the measured values into a computer. The computer then used the Arrhenius equation to calculate when sufficient energy had been absorbed so that the molding machine should open the press.

The claims

Independent claim 1 of the allowed patent is representative. It provides:

<blockquote>1. A method of operating a rubber-molding press for precision molded compounds with the aid of a digital computer, comprising: