Robert F. Johnson has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
Abstract: Titanium based and nickel based castings are made by casting a suitable melt having a relatively low melt superheat into a mold cavity defined by one or more low carbon steel or titanium mold members where the melt solidifies to form the desired casting. The melt super-heat is limited so as not to exceed about 150.degree. F. above the liquidus temperature of the particular melt being cast. For a steel mold, one or more titanium melt inlet-forming members are provided for cooperating with the steel mold members to form an melt ingate that communicates to the mold cavity for supplying the melt thereto in a manner to avoid harmful iron contamination of the melt during casting. The mold body-to-mold cavity volume ratio is controlled between 10:1 to 0.5:1 to minimize casting surface defects and mold wear/damage.
September 11, 1992
Date of Patent:
February 22, 1994
Gregory N. Colvin, Leonard L. Ervin, Robert F. Johnson
Abstract: Radiant energy, preferably that of a laser, is focused onto the surface of a silicon integrated circuit that contains a thin layer doped to the opposite conductivity type of the underlying silicon. The thin layer can be trimmed so as to tailor its conductivity. Such layers when used in JFET, diode, bipolar transistor, or resistor structures can therefore be precision trimmed. In particular, JFET pairs can be trimmed to a very close match.