Samsung patents hinge design with mixed springs for foldable phones

1. A foldable electronic device, comprising: a first housing and a second housing; a hinge structure coupled between the first housing and the second housing; and a flexible display accommodated in the first housing and the second housing, wherein the hinge structure includes: a first rotation member coupled to the first housing and a second rotation member coupled to the second housing; a first arm member configured to rotate in response to the rotation of the first rotation member and a second arm member configured to rotate in response to the rotation of the second rotation member; a first shaft on which a first main gear is disposed and coupled to the first arm member; a second shaft on which a second main gear is disposed and coupled to the second arm member; a third shaft disposed between the first main gear and the second main gear and on which a first gear is disposed; a fourth shaft disposed between the third shaft and the second main gear and on which a second gear is disposed; first to fourth cams coupled to each of the first to fourth shafts; a cam member coupled to each of the first to fourth shafts and including first to fourth fixed cam portion facing the first to fourth cams respectively; a first elastic member coupled to the first shaft, and configured to provide a first elastic force to the first cam; a second elastic member coupled to the second shaft and configured to provide the first elastic force to the second cam; a third elastic member coupled to the third shaft and configured to provide a second elastic force different from the first elastic force to the third cam; and a fourth elastic member coupled to the fourth shaft and configured to provide the second elastic force to the fourth cam, wherein a magnitude of slope of the first cam is different from a magnitude of slope of the third cam, and wherein a type of the first elastic member is different from a type of the third elastic member.