US Patent 6942061 US Patent Issued on September 13, 2005 <a href="http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.htm&r=1&p=1&f=G&l=50&d=PTXT&S1=6942061.PN.&OS=pn/6942061&RS=PN/6942061" target="_blank">http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.htm&r=1&p=1&f=G&l=50&d=PTXT&S1=6942061.PN.&OS=pn/6942061&RS=PN/6942061</a>