Kentucky patents The U.S. Patent Office issues patents weekly. These patents were issued Tuesday for inventors in the Lexington area: Method and apparatus for effecting synchronous pulse generation for use in variable-speed serial communications. Inventors: David Crutchfield, Timothy Rademacher and Galen Rasche, all of Lexington. Patent 7,139,344 assigned to Lexmark International Inc., Lexington.Toner housing plug with toner level sensor. Inventors: Benjamin Askren, Peter Bayerle and Donn Bryant, all of Lexington. Patent 7,139,505 assigned to Lexmark.Two-part cartridges with force biasing by printer. Inventors: Philip Carter, Julia Fain and Mark Foster, all of Lexington. Patent 7,139,510 assigned to Lexmark.