Patent ID: 8511676
Filing Date: 2013-08-20
Classification: B65H

Abstract:
1. A medium feeding device comprising: a main body; a medium placing member mounted to said main body so that said medium placing member is movable upward and downward; a feeding mechanism shiftably mounted to said main body, said feeding mechanism contacting a surface of said medium and feeding said medium in a predetermined direction; a conveying mechanism for conveying said medium fed by said feeding mechanism; a lifting unit that moves said medium placing member toward said feeding mechanism; a medium detecting unit for detecting presence and absence of said medium on said medium placing member; a driving source for driving at least one of said lifting unit and said conveying mechanism; a driving force transmission unit for transmitting a driving force of said driving source to said lifting unit, said driving force transmission unit including a first sun gear; and a control unit that controls said driving source, wherein said driving force transmission unit comprises: a first switching unit that connects or disconnects a transmission of said driving force from said driving source to said lifting unit based on a shifting of said feeding mechanism caused by a movement of said medium placing member, and a second switching unit that connects or disconnects a transmission of said driving force from said driving source to said lifting unit based on control by said control unit, wherein said control unit causes said second switching unit to transmit said driving force to said lifting unit so as to move said medium placing member upward based on detection by said medium detecting unit, wherein, when said medium placing member moves upward to a predetermined position, said first switching unit disconnects said transmission of said driving force to said lifting unit so that said medium placing member is held at said predetermined position, and wherein said control unit causes said second switching unit to disconnect said transmission of said driving force to said lifting unit so that said medium placing member moves downward, wherein said lifting unit includes: a first planet gear that meshes with an external tooth portion of said first sun gear of said driving force transmission unit; an internal tooth rack provided so as to face said external tooth portion, said internal tooth rack meshing with said first planet gear, and a swinging member mounted to said planet gear, wherein, when said first sun gear rotates, said first planet gear revolves around said first sun gear, and said swinging member moves upward to cause said medium placing member to move upward.