david0vincent, Ashley : It's not the keyboard fault. It's just the way Safari on iOS handle keyboard events.
From http://stackoverflow.com/a/4804590 :
Safari for iOS doesn't trigger keyboard events on DOM elements that are not components of a form. This includes the document and body which are usually used to capture keystrokes anywhere on the page.
The only way to trigger a keystroke event on document or body of a page is to trigger it in an input or textarea. In that case, the event will correctly 'bubble' to the body and document.
At the moment, we are using a solution where user has to click on an input field before starting the first scan, and the input field is then moved off-screen but retains focus.