You can utilize javascript's in-built method setInterval to accomplish this.
Here's a quick solution that I can think of,
Let me know if you 've any questions.
var picPaths = ['iphone1.png','iphone2.png','iphone3.png'];
var imageIndex = 0;
var bannerImage;
function startInterval() {
setInterval(displayNextImage, 3000);
}
function displayNextImage() {
bannerImage.src = picPaths[imageIndex];
if(imageIndex === (picPaths.length-1)) {
imageIndex = 0;
}
else {
imageIndex = imageIndex + 1;
}
}
window.onload=function() {
bannerImage = document.getElementById('imgBanner');
startInterval();
}