Automatic Reaction to Door Slam
FingersKeeper does not interfere with the opening and closing of the door in normal use. It only goes into action when the door slams at a higher speed than the speed FingersKeeper is set to detect. Once detecting a door slam, FingersKeeper reacts instantly, creating a gap between the door and the frame.
Now let’s take a look at the physics behind FingersKeeper that allows it to do its magic.
The picture above shows the inside mechanism of FingersKeeper. In normal use of the door, gravity holds the door stopping arm in vertical position, not interfering with the door. In the event of a door slam, the arm will impinge against the diagonal slope, and the door's linear acceleration will be converted to side movement of the arm. The door stopping arm will stick out of FingersKeeper's case, jamming the door and creating a gap between the door and the door frame. Once the arm is out of the case, the magnet on top of the door stopping arm will attract the metal bracket and keep FingersKeeper in the door jamming mode. A quick push on the arm will re-position it inside the case, resetting FingersKeeper and arming it for the next door slam.