in settings/display/screen timeout you can change screen timeout to a maximum of 10 minutes. alternatively goto settings and search smart stay. it keeps your screen on as long as you are looking at it.
just thought of a way it will stay on permanently but you will need a USB battery backup for travel.
enable developers options in your settings.(Google how to activate) goto developers options and look for stay awake option and select it. your screen will never go off while charging.