Foldable display device having a hinge structure allowing for inner folding

A foldable display device, comprising:

• a first support plate and a second support plate;
• a display panel disposed on the first support plate and the second support plate;
• a hinge assembly disposed between the first support plate and the second support plate,
• wherein the hinge assembly includes:
• a first hinge arm and a second hinge arm rotatably connected to each other;
• a first virtual axis gear coupled to the first hinge arm;
• a second virtual axis gear coupled to the second hinge arm;
• a first rotational gear and a second rotational gear disposed to mesh with each other between the first virtual axis gear and the second virtual axis gear;
• a first gear arm and a second gear arm fastened to interlock with the first virtual axis gear and the second virtual axis gear;
• a cam frame to which one side of the first virtual axis gear and one side of the second virtual axis gear are rotatably coupled;
• and
• an inner frame that provides a through groove to which the cam frame is attached to fix an inside of the hinge assembly;
• a hinge housing disposed below the hinge assembly, the hinge housing including an internal space that receives the inner frame and a fastening member that fixes the inner frame by engaging with the through groove;
• a first compression spring provided on outer surfaces of the first virtual axis gear and the second virtual axis gear between a first cam and a second cam;
• and
• a second compression spring provided on outer surfaces of the first virtual axis gear and the second virtual axis gear between the second cam and the inner frame,
• wherein the first virtual axis gear meshes with the first rotational gear, and the second virtual axis gear meshes with the second rotational gear, and
• wherein the first support plate, the second support plate, and the display panel perform folding and unfolding operations about a rotation axis different from central axes of the first virtual axis gear and the second virtual axis gear.