Patents Issued in 1991
- December 31, 1991
- December 24, 1991
- December 17, 1991
- December 10, 1991
- December 3, 1991
- November 26, 1991
- November 19, 1991
- November 12, 1991
- November 5, 1991
- October 29, 1991
- October 22, 1991
- October 15, 1991
- October 8, 1991
- October 1, 1991
- September 24, 1991
- September 17, 1991
- September 10, 1991
- September 3, 1991
- August 27, 1991
- August 20, 1991
- August 13, 1991
- August 6, 1991
- July 30, 1991
- July 23, 1991
- July 16, 1991
- July 9, 1991
- July 2, 1991
- June 25, 1991
- June 18, 1991
- June 11, 1991
- June 4, 1991
- May 28, 1991
- May 21, 1991
- May 14, 1991
- May 7, 1991
- April 30, 1991
- April 23, 1991
- April 16, 1991
- April 9, 1991
- April 2, 1991
- March 26, 1991
- March 19, 1991
- March 12, 1991
- March 5, 1991
- February 26, 1991
- February 19, 1991
- February 12, 1991
- February 5, 1991
- January 29, 1991
- January 22, 1991
- January 15, 1991
- January 8, 1991
- January 1, 1991
