Electronic apparatus comprising two casing coupled together with two-parallel-axis hinge

Abstract

According to one embodiment, an electronic apparatus includes a first casing, a second casing, and a hinge which couples them rotatably from a first state to a second state. The hinge includes a first shaft, a first rotation engaging portion, a second shaft, a second rotation engaging portion, a housing, and a transmission unit. The transmission unit links the first engaging portion and the second engaging portion and rotates them with respect to a rotation angle of the housing from the first state to the second state.

What is claimed is: 
     
         1 . An electronic apparatus comprising:
 a first casing comprising a first surface and a second surface opposite to the first surface;   a second casing comprising a third surface and a fourth surface opposite to the third surface; and   a hinge coupling the second casing with the first casing continuously rotatably from a first state in which the first casing and the second casing are superimposed with the third surface caused to face the first surface to a second state in which the first casing and the second surface are superimposed with the fourth surface caused to face the second surface, wherein   the hinge comprises:   a first shaft fixed to the first casing;   a first rotation engaging portion fixed to the first shaft;   a second shaft fixed to the second casing;   a second rotation engaging portion fixed to the second shaft;   a housing holding the first shaft and the second shaft in parallel; and   a transmission unit linking rotation angles of the first rotation engaging portion and the second rotation engaging portion with respect to the housing from the first state to the second state such that a line segment connecting a center of the first shaft with a center of the second shaft in a radial direction makes an acute angle with the first casing and makes an obtuse angle with the second casing in either of the first state and the second state.   
     
     
         2 . The electronic apparatus of  claim 1 , wherein
 the first casing has a first size from the first surface to the second surface, and   the second casing has a second size from the third surface to the fourth surface, and the second size is smaller than the first size.   
     
     
         3 . The electronic apparatus of  claim 2 , wherein
 the first rotation engaging portion comprises a first helical gear,   the second rotation engaging portion comprises a second helical gear having an external diameter larger than an external diameter of the first helical gear, and   the transmission unit comprises a third helical gear disposed between the first helical gear and the second helical gear and in a direction orthogonal to a rotation center line, to link a rotation direction of the second helical gear oppositely to a rotation direction of the first helical gear.   
     
     
         4 . The electronic apparatus of  claim 2 , wherein
 the first rotation engaging portion comprises a first spur gear,   the second rotation engaging portion comprises a second spur gear having an external diameter larger than an external diameter of the first spur gear, and   the transmission unit comprises at least two third spur gears disposed in parallel with the first spur gear and the second spur gear, to link a rotation direction of the second spur gear oppositely to a rotation direction of the first spur gear.   
     
     
         5 . The electronic apparatus of  claim 2 , wherein
 the first rotation engaging portion comprises a first spur gear,   the second rotation engaging portion comprises a second spur gear, and   the transmission unit comprises at least one speed change gear having a speed change ratio to set a rotation angle of the second spur gear smaller than a rotation angle of the first spur gear, and a transmission gear disposed between the first spur gear and the speed change gear or between the second spur gear and the speed change gear, to link a rotation direction of the second spur gear oppositely to a rotation direction of the first spur gear.   
     
     
         6 . The electronic apparatus of  claim 2 , wherein
 the first rotation engaging portion comprises a first cam roller including a first spiral groove in a cylindrical surface thereof parallel with the first shaft,   the second rotation engaging portion comprises a second cam roller including a second spiral groove in a direction opposite to a direction of the first spiral groove in a cylindrical surface thereof parallel with the second shaft, the cylindrical surface having an external diameter larger than an external diameter of the first cam roller, and   the transmission unit comprises an engaging element movable in a direction along centers of the first shaft and the second shaft, the engaging element is fitted at an equal position with the first spiral groove and the second spiral groove, to synchronize rotation angles of the first cam roller and the second cam roller.   
     
     
         7 . The electronic apparatus of  claim 2 , wherein
 the first rotation engaging portion comprises a first cam roller including a first spiral groove in a cylindrical surface thereof parallel with the first shaft,   the second rotation engaging portion comprises a second cam roller including a second spiral groove in a direction opposite to a direction of the first spiral groove in a cylindrical surface thereof parallel with the second shaft, the cylindrical surface having an external diameter equal to an external diameter of the first cam roller, the second spiral groove having a spiral pitch larger than a spiral pitch of the first spiral groove, and   the transmission unit comprises an engaging element movable in a direction along centers of the first shaft and the second shaft, the engaging element is fitted at an equal position with the first spiral groove and the second spiral groove, to synchronize rotation angles of the first cam roller and the second cam roller.