Mechanism and method of multiple documents feeding detection

A multiple documents feeding detection method, comprising:

• providing an advancing roller applied a driving torque;
• providing a retarding roller applied a resisting torque less than the driving torque, and against the advancing roller for transporting one piece of document;
• monitoring an action of the retarding roller by a detecting means to detect whether the multiple documents being fed into a nip between the advancing roller and the retarding roller;
• wherein the friction coefficient of a surface of the advancing roller is greater than the friction coefficient of a surface of the retarding roller, and the friction coefficient of the surface of the retarding roller is greater than the friction coefficient of the fed documents,
• wherein if multiple documents are fed into the nip, then the friction of the surface of the retarding roller-to-the document is greater than the friction between the documents to remain the retarding roller be in standstill.

A multiple documents feeding detection mechanism, comprising:

• an advancing roller having a surface with a first friction coefficient;
• a driving mean providing a driving torque to the advancing roller;
• a retarding roller having a surface with a second friction coefficient, against the advancing roller for transporting one piece of document with a third friction coefficient;
• a clutch providing a resisting torque to the retarding roller, the resisting torque being less than the driving torque, if there are multiple documents fed into the nip, then the retarding roller remains in standstill;
• a disk driven into action with the retarding roller, having a first tuning portion and a second tuning portion;
• a source radiating a beam to the disk;
• a sensor sending a first signal according to a received variable intensity of the beam radiated from the source and then alternately tuning by the first tuning portion and the second tuning portion due to movement of the disk, and sending a second signal according to a received constant intensity of the beam radiated from the source and then tuning by one of the first tuning portion and the second tuning portion due to standstill of the disk;
• and
• a processor connected to the sensor, determining multiple documents fed into the nip according to a received second signal from the sensor, and determining that there is one single document fed into the nip according to a received first signal from the sensor.

A multiple documents feeding detection method, comprising:

• providing an advancing roller;
• applying a driving torque to the advancing roller;
• providing a retarding roller against the advancing roller for transporting one piece of document;
• applying a resisting torque to the retarding roller;
• setting the friction coefficient of a surface of the advancing roller be greater than the friction coefficient of a surface of the retarding roller, the driving torque be greater than the resisting torque, to urge the retarding roller into rotation when only one single document fed into a nip between the advancing roller and the retarding roller, and urge the retarding roller be in standstill when multiple documents fed into the nip;
• providing a disk with a first tuning portion and a second tuning portion, driven into action with the retarding roller;
• radiating a beam to the disk;
• determining there is one single document fed into the nip according to a received variable intensity of the beam alternately tuned by the first tuning portion and the second tuning portion due to the movement of the disk;
• determining that there are multiple documents fed into the nip according to a received constant intensity of the beam tuned by one of the first tuning portion and the second tuning portion due to standstill of the disk.