Friction transport device and paper sheet transport device

A paper sheet transport device comprising:

• a friction transport device comprising:
• a drive-side unit that transmits a transport driving force to one surface of a paper sheet transported along a transport path;
• and
• a drive motor that supplies a driving force to the drive-side unit;
• a driven roller that is arranged to oppose the drive-side unit and that followingly rotates in contact with the other surface of the paper sheet
• wherein the drive-side unit includes:
• a drive roller that rotates on a shaft part orthogonal to a normal paper sheet transport direction, and
• a transport grip adjustment mechanism comprising:
• a rocking arm that includes the shaft part at one portion thereof and that has another portion thereof pivotally supported by a rocking shaft so as to change a transport grip by rocking the drive roller to change a distance from the driven roller, and
• an elastic biasing member that elastically biases the drive roller toward the driven roller via the rocking arm,
• an input gear that is pivotally supported to be rotatable about the rocking shaft and that rotates upon reception of the driving force from the drive motor,
• an output gear that is coaxially integrated with the drive roller and that meshes with the input gear to receive transmission of a driving force, and
• a stopper member that defines an upper limit position of the rocking arm,
• wherein:
• the output gear is capable of revolving on an outer circumference of the input gear according to increase or decrease of load applied to the drive roller, and
• the output gear rocks the rocking arm in a direction to cause the rocking arm to be in pressure contact with the stopper member when transport load equal to or above a predetermined value is applied to the paper sheet positioned between the drive roller and the driven roller at a time of reverse rotation of the drive roller, and
• wherein the transport grip adjustment mechanism is configured to cause the drive roller to retreat in a direction away from the driven roller against a biasing force from the elastic biasing member to decrease the transport grip when transport load applied to the drive roller from the paper sheet transported on the transport path by the drive roller forwardly rotating changes beyond a predetermined value;
• a paper sheet detection sensor that detects entry of a paper sheet into the transport path;
• and
• a control unit that controls the drive motor, wherein the control unit actuates the drive motor to forwardly rotate the drive roller based on a paper sheet entry detection signal from the paper sheet detection sensor.