var banner = new Array();

banner.push('http://www.patmax.eu/I1/110227055251.jpg');
banner.push('http://www.patmax.eu/I1/110227055402.jpg');
banner.push('http://www.patmax.eu/I1/110227055428.jpg');
banner.push('http://www.patmax.eu/I1/110227055456.jpg');

document.getElementById('i_logo').src= banner[Math.floor(Math.random()*banner.length)];