Lifting apparatus and sheet storage apparatus

Abstract

A lifting apparatus includes a motor, circular support members, power transmission members, guide mechanisms, and electromagnets. The circular support members provide tensile forces to wires connected to a load. The power transmission members rotate around the rotation axis Ax as a center of rotation by driving force of the motor. The guide mechanisms support the circular support members so as to enable the circular support members to slide in a predetermined ranges along a radial direction of the rotation axis, respectively. The electromagnets forcibly arrange the circular support members using electromagnetic force at a position that the center axes of the circular support members agree with the rotation axis in the predetermined ranges.

What is claimed is: 
     
         1 . A lifting apparatus that causes a load to move up and down, comprising:
 a motor;   a first circular support member configured to provide tensile force to a first wire connected to the load;   a first power transmission member configured to rotate around a rotation axis as a center of rotation by driving force of the motor;   a first guide mechanism configured to support the first circular support member so as to enable the first circular support member to slide in a predetermined first range along a radial direction of the rotation axis;   a first electromagnet configured to forcibly arrange the first circular support member using electromagnetic force at a position that a center axis of the first circular support member agrees with the rotation axis in the predetermined first range;   a second circular support member configured to provide tensile force to a second wire connected to the load;   a second power transmission member configured to rotate around the rotation axis as a center of rotation by driving force of the motor;   a second guide mechanism configured to support the second circular support member so as to enable the second circular support member to slide in a predetermined second range along a radial direction of the rotation axis; and   a second electromagnet configured to forcibly arrange the second circular support member using electromagnetic force at a position that a center axis of the second circular support member agrees with the rotation axis in the predetermined second range.   
     
     
         2 . The lifting apparatus according to  claim 1 , further comprising a rotator configured to rotate by driving force of the motor;
 wherein the first power transmission member is fixed at an end of the rotator; and   the second power transmission member is fixed at another end of the rotator.   
     
     
         3 . The lifting apparatus according to  claim 1 , wherein
 the first and second power transmission members comprise guide holes along the radial directions, respectively;   the first and second circular support members comprises protrusion parts to be arranged in the guide holes, respectively; and   the first and second guide mechanism comprises the guide holes and the protrusion parts, respectively.   
     
     
         4 . The lifting apparatus according to  claim 3 , wherein
 the first and second power transmission members are nonmagnetic members; and   the protrusion parts are magnetic members.   
     
     
         5 . The lifting apparatus according to  claim 1 , wherein in a power off status, the electromagnetic force of the first and second electromagnets disappears, and the first and second circular support members slide in accordance with the first and second guide mechanisms until torque applied to the motor by the tensile force of the first and second wires due to the load becomes substantially zero. 
     
     
         6 . The lifting apparatus according to  claim 1 , wherein an angle between a direction of the first guide mechanism and a direction of the second guide mechanism is a predetermined angle other than 180 degrees. 
     
     
         7 . A sheet storage apparatus, comprising:
 a lifting apparatus; and   a sheet loading unit configured to be caused to move up and down by the lifting apparatus;   wherein the lifting apparatus comprises:
 a motor; 
 a first circular support member configured to provide tensile force to a first wire connected to the sheet loading unit; 
 a first power transmission member configured to rotate around a rotation axis as a center of rotation by driving force of the motor; 
 a first guide mechanism configured to support the first circular support member so as to enable the first circular support member to slide in a predetermined first range along a radial direction of the rotation axis; 
 a first electromagnet configured to forcibly arrange the first circular support member using electromagnetic force at a position that a center axis of the first circular support member agrees with the rotation axis in the predetermined first range; 
 a second circular support member configured to provide tensile force to a second wire connected to the sheet loading unit; 
 a second power transmission member configured to rotate around the rotation axis as a center of rotation by driving force of the motor; 
 a second guide mechanism configured to support the second circular support member so as to enable the second circular support member to slide in a predetermined second range along a radial direction of the rotation axis; and 
 a second electromagnet configured to forcibly arrange the second circular support member using electromagnetic force at a position that a center axis of the second circular support member agrees with the rotation axis in the predetermined second range.