url encode

Hi,
i'm trying to get this url but i get an error:

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=%22clear+dead%22&OS=%22clear+dead%22&RS=%22clear+dead%22

my $response = $ua->get($url);

how should i encode it? I've tried to use uri_escape function but it
fails...

Thanks
T