You should consider checking out the Easy Out DELUXE Remote Pet Door Opener... applied in this case for releasing chickens. Here is the product's website: http://easyoutpetrelease.com
It is available for ordering any time and the website has lots of videos showing how to install it in many different applications and ways. Horizontally swinging doors are easy for it, but one chicken farmer even installed it on ramp that swings down vertically. Here is a link to where he posted all about his setup:http://www.backyardchickens.com/t/907179/solution-automatic-drop-down-ramp-style-door-opener
Regardless of how you apply it, it's a proven and affordable way to open your coop door via any common AC wall socket plug-in timer (with extension cords to extend the reach as necessary) every morning, and never get up early to do so again.
And as another option, the website tells how you can also easily set it up so you can open the door USING YOUR SMART PHONE, anytime, from anywhere, using a wifi switch and a free app. And on top of those methods it can also be opened with an included hand held remote control from up to 100 feet away.
Unlike other options on the internet, this product adapts as an add-on to your existing coop door so it does not require motors, pulleys, nor any other major changes to your current structure, and it costs under $100