var banner = new Array();

banner.push('adresse_image_1');
banner.push('adresse_image_2');
banner.push('adresse_image_3');

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

setInterval("document.getElementById('logo').firstChild.src= banner[Math.floor(Math.random()*banner.length)];",3000);