US Patent 9840861 Hinged device with snap open lock

A hinge mechanism is described wherein a multi-part device (e.g., dual-display device) can move to a snap-open position. In the snap-open position, the parts lock into place when they approach 180 degrees of rotation relative to one another. The locking force in the open position is sufficient that holding or using the multi-part device does not cause an accidental closing action. An unlocking force is required to unlock the device from the open position. Additionally, the locking force drops off precipitously when the two parts are unlocked and rotating away from the locked position.