Hinge module and foldable electronic device including the same

1. A hinge module comprising:

a first fixed structure including a first central portion, a first support portion extending from the first central portion in a first direction, and a first guide portion extending from the first support portion in a third direction perpendicular to the first direction;

a first connecting shaft including a first gear formed on at least a central part of an outer circumferential surface thereof, the first connecting shaft extending in the first direction, wherein at least a part of the first gear is disposed between the first central portion and the first guide portion;

a first sub-gear engaged with the first gear, wherein the first fixed structure includes a first guide structure formed on the first central portion and a second guide structure formed on the first guide portion;

a first rotary structure, including a first guide rail having a first radius of curvature coupled to the first guide structure and a second guide rail having a second radius of curvature coupled to the second guide structure, the first and second radii of curvature defined with respect to a first axis of rotation wherein the first rotary structure is configured to be rotated about the first axis of rotation while the first connecting shaft rotates, at least a portion of the first rotary structure is disposed between the first guide portion and the first central portion;

a second fixed structure including a second central portion coupled to one side of the first central portion that faces a second direction opposite to the first direction, a second support portion extending from the second central portion in the second direction, and a second guide portion extending from the second support portion in a fourth direction perpendicular to the second direction, the second fixed structure includes a third guide structure formed on the second central portion and a fourth guide structure formed on the second guide portion and the second fixed structure being integrally or removably coupled to the first fixed structure;

a second connecting shaft including a second gear formed on at least a central part of an outer circumferential surface thereof, the second connecting shaft extending in the second direction, wherein at least a part of the second gear is disposed between the second central portion and the second guide portion;

a second sub-gear engaged with the second gear, wherein the first connecting shaft and the second connecting shaft are linked with each other by the first sub-gear and the second sub-gear so as to be rotated in opposite directions; and

a second rotary structure including a third guide rail having a third radius of curvature coupled to the third guide structure and a fourth guide rail having a fourth radius of curvature coupled to the fourth guide structure, the third and fourth radii of curvature defined with respect to a second axis of rotation, wherein the second rotary structure is configured to be rotated about the second axis of rotation while the second connecting shaft rotates, at least a portion of the second rotary structure is disposed between the second guide portion and the second central portion,

wherein the second axis of rotation is parallel to a longitudinal center line of the hinge module and is offset from the longitudinal center line by a first predetermined distance on one side of the longitudinal center line, and the first axis of rotation is parallel to the longitudinal center line and is offset from the longitudinal center line by a second predetermined distance on another side of the longitudinal center line.

2. The hinge module of claim 1 , wherein the first central portion faces a direction of the first axis of rotation, and

wherein the first support portion faces a direction perpendicular to the direction of the first axis of rotation.

3. The hinge module of claim 1 , wherein the first rotary structure has a first circular arc shaped gear and a circular arc shaped opening formed therein through which at least a part of the first connecting shaft passes, and

wherein the first circular arc shaped gear is a first internal gear formed on an inner wall of the circular arc shaped opening and engaged with the first gear of the first connecting shaft.

4. The hinge module of claim 3 , wherein the first internal gear is between the first connecting shaft and the first axis of rotation.

5. The hinge module of claim 1 , wherein the first guide structure and the second guide structure protrudes toward a space between the first central portion and the first guide portion, respectively.

6. The hinge module of claim 5 , wherein the first guide rail and the second guide rail include first curved surfaces spaced apart from the first axis of rotation by a first distance in a radial direction and second curved surfaces spaced apart from the first axis of rotation by a second distance in the radial direction, respectively, and

wherein the first guide structure and the second guide structure are received between the first curved surfaces and the second curved surfaces.

7. The hinge module of claim 6 , wherein the first guide structure includes first corresponding curved surfaces configured to make contact with the first curved surfaces of the first guide rail and the second guide structure includes second corresponding curved surfaces configured to make contact with the second curved surfaces of the second guide rail, and

wherein central angles of circular arcs of the second corresponding curved surfaces are smaller than central angles of circular arcs of the second curved surfaces.

8. The hinge module of claim 1 , wherein the first support portion includes a curved surface formed to support rotation of the first rotary structure.

9. The hinge module of claim 1 , wherein the first rotary structure has a first circular arc shaped gear and a first opening formed therein in a first circular arc shape,

wherein the first circular arc shaped gear is a first internal gear formed on an inner wall of the first opening and engaged with the first gear of the first connecting shaft,

wherein the second rotary structure has a second circular arc shaped gear and a second opening formed therein in a second circular arc shape, and

wherein the second circular arc shaped gear is a second internal gear formed on an inner wall of the second opening and engaged with the second gear of the second connecting shaft.

10. The hinge module of claim 1 , wherein the first rotary structure includes a first curved surface having the first radius of curvature with respect to the first axis of rotation,

wherein the first support portion includes a first corresponding curved surface configured to support the first curved surface to support rotation of the first rotary structure,

wherein the second rotary structure includes a second curved surface having the third radius of curvature with respect to the second axis of rotation, and

wherein the second support portion includes a second corresponding curved surface configured to support the second curved surface to support rotation of the second rotary structure.

11. The hinge module of claim 9 , wherein the first circular arc shaped gear is between the first connecting shaft and the first axis of rotation in a radial direction from the first axis of rotation, and

wherein the second circular arc shaped gear is between the second connecting shaft and the second axis of rotation in a radial direction from the second axis of rotation.

12. The hinge module of claim 1 , wherein the hinge module is disposed in the hinge housing and configured to rotate a first housing about the first axis of rotation extending in the first direction and rotate a second housing about the second axis of rotation parallel to the first axis of rotation.

13. The hinge module of claim 1 , wherein the second axis of rotation is offset from the first axis of rotation by twice the first predetermined distance.

14. The hinge module of claim 1 , wherein the first predetermined distance is same as the second predetermined distance.