Sheet feeding apparatus, image reading apparatus equipped with the same, and method of detecting double feed

• US 20050127597A1
• Filed: 12/03/2004
• Published: 06/16/2005
• Est. Priority Date: 12/04/2003
• Status: Active Grant

• Current Assignee: Nisca Corporation (Canon Inc.)
• Original Assignee: Nisca Corporation (Canon Inc.)
• Inventors: Sano, Kazuhide, Hirose, Syunichi
• Granted Patent: US 7,552,924 B2
• Time in Patent Office: Days
• US Class Current: 271/258.10
• CPC Class Codes: B65H 2220/01 indicating an entity as a function of which control, adjustment or change is performed, i.e. input
• CPC Class Codes: B65H 2220/03 indicating an entity which is measured, estimated, evaluated, calculated or determined but which does not constitute an entity which is adjusted or changed by the control process per se
• CPC Class Codes: B65H 2511/10 Size; Dimensions
• CPC Class Codes: B65H 2511/11 Length
• CPC Class Codes: B65H 2553/30 using acoustic or ultrasonic elements
• CPC Class Codes: B65H 2553/40 using optical, e.g. photographic, elements
• CPC Class Codes: B65H 7/125 sensing the double feed or separation without contacting the articles

Abstract

A sheet feeding apparatus includes two transport devices arranged in a sheet guide that guides a sheet from a stacker to a processing position for reading an image or printing. A double feed detection device is arranged between the transport devices for detecting a double feed of the sheets over a predetermined length region (measurement length). A sheet length recognition device is provided for recognizing at least two portions of a length of the sheet stacked on the stacker in a transport direction, and a judgment device is provided for judging the double feed of the sheets based upon detection data from the double feed detection device. The judgment device judges the double feed of the sheets according to detection data of one measurement region selected from a plurality of measurement regions based on information obtained from the sheet length recognition device.

Claims

1. A sheet feeding apparatus comprising:

a stacker for stacking a sheet,

a sheet guide for guiding the sheet from the stacker to a predetermined processing position,

first and second transport devices arranged in the sheet guide for transporting the sheet,

a sheet length recognition device for recognizing at least two kinds of length of a sheet placed on the stacker in a transport direction,

a double feed detection device arranged between the first transport device and the second transport device for detecting a double feed of sheets over a measurement region of the sheet, and

a judgment device for judging the double feed based upon detection data of the one measurement region sent from the double feed detection device, said judgment device selecting one measurement region from a plurality of measurement regions according to the length of the sheet recognized by the sheet length recognition device.

2. A sheet feeding apparatus according to claim 1, wherein said first transport device includes a separating roller for separating the sheet stacked on the stacker, and said second transport device includes a register roller for temporarily holding the sheet from the separating roller.

3. A sheet feeding apparatus according to claim 1, wherein said sheet length recognition device includes a sensor for detecting an edge of the sheet stacked on the stacker.

4. A sheet feeding apparatus according to claim 2, wherein said separating roller and said register roller are connected to a drive device so that the separating roller and the register roller rotate in opposite directions, said judgment device judging the double feed based on data from the double feed detection device while the register roller is being rotated.

5. A sheet feeding apparatus according to claim 1, wherein said double feed detection device includes an oscillating element and a receiving element arranged such that the sheet passes between the oscillating element and the receiving element for detecting an amount of an ultrasonic wave or light passing through the sheet.

6. A sheet feeding apparatus according to claim 1, wherein said sheet length recognition device includes a sensor for detecting an edge of the sheet stacked on the stacker and a device for judging the length of the sheet in the transport direction based on a detection signal of the sensor, said judgment device setting the measurement region based upon the length of the sheet in the transport direction.

7. A sheet feeding apparatus according to claim 1, wherein said sheet length recognition device includes a device for detecting the length of the sheet in the transport direction, said judgment device setting the measurement region by subtracting a predetermined length from the length of the sheet.

8. A sheet feeding apparatus according to claim 1, wherein said judgment device sets the measurement region so that non-measurement regions are formed at a leading edge and a trailing edge of the sheet in the transport direction.

10. An image reading apparatus comprising the sheet feeding apparatus according to claim 1, and a control device for canceling reading of an image on the sheet based on a signal from the judgment device.

9. A sheet feeding apparatus comprising:

a stacker for stacking a sheet,

a separating transport device for sequentially separating and feeding sheets on the stacker one by one,

a register transport device arranged at a downstream side of the separating transport device for temporarily holding the sheet from the separating transport device, said register transport device being situated away from the separating transport device by a distance smaller than a length of a minimum size sheet in a transport direction,

a drive device for driving the separating transport device and the register transport device,

a sheet length recognition device for recognizing at least two kinds of length of the sheet placed on the stacker in the transport direction,

a double feed detection device disposed between the separating transport device and the register transport device for detecting a double feed of sheets over a predetermined region of the length of the sheet, and

a judgment device for judging an erroneous feed of the sheet based upon detection data from the double feed detection device, said judgment device judging the erroneous feed based on detection data over a measurement region corresponding to the length of the sheet in the transport direction recognized by the sheet length recognition device and non-measurement regions formed at a leading edge and a trailing edge of the sheet.

11. A method of detecting a double feed of sheets, comprising:

a first step of identifying at least two kinds of length of a sheet in a transport direction,

a second step of detecting the double feed of sheets with a double feed detection sensor while the sheet is being transported,

a third step of setting a measurement region based on the length of the sheet recognized in the first step, and

a fourth step of judging an erroneous transport of the sheet based on detection data from the double feed detection sensor over the measurement region set in the third step.

12. A sheet feeding apparatus comprising:

a stacker for stacking a sheet,

a transport guide for guiding the sheet from the stacker to a predetermined processing position,

first and second transport devices arranged in the transport guide for transporting the sheet,

a sheet size recognition device for recognizing length of the sheet placed on the stacker in a transport direction,

a double feed detection device arranged between the first transport device and the second transport device for detecting a double feed of sheets,

a transport length detection device for detecting a transport length of the sheet transported by the first and second transport devices from a leading edge of the sheet to a trailing edge of the sheet,

a comparison device for comparing the length of the sheet recognized by the sheet size recognition device and the transport length of the sheet detected by the transport length detection device, and

a judgment device for judging an erroneous feed of the sheet based on a comparison result from the comparison device and a detection result from the double feed detection device.

18. An image reading apparatus comprising the sheet feeding apparatus according to claim 12, a platen having a photoelectric converting device for reading an image on the sheet, said stacker supplying the sheet to the platen, a sheet discharge stacker for storing the sheet from the platen, and a control device for canceling reading of the image at the platen based on a signal from the judgment device.

13. A sheet feeding apparatus comprising:

a stacker for stacking a sheet,

a transport guide for guiding the sheet from the stacker to a processing platen,

a separating device for separating and feeding sheets on the stacker,

at least one transport device for transporting the sheet from the separating device to the processing platen,

a double feed detection device arranged between the separating device and the one transport device for detecting a double feed of sheets,

a transport length detection device arranged in the transport guide for detecting a transport length of the sheet from a leading edge of the sheet to a trailing edge of the sheet,

a comparison device for comparing the transport length detected by the transport length detection device with a reference length, and

a judgment device for judging an erroneous feed of the sheet based on a detection result from the double feed detection device and a comparison result from the comparison device.

14. A sheet feeding apparatus according to claim 13, wherein said comparison device compares the transport length with the reference length set to be a length of a maximum sheet in a transport direction.

15. A sheet feeding apparatus according to claim 13, wherein said transport device includes a register roller for temporarily holding the sheet.

16. A sheet feeding apparatus according to claim 13, wherein said double feed detection device includes a sensor for detecting an amount of an ultrasonic wave or light passing through the sheet.

17. A sheet feeding apparatus according to claim 13, wherein said separating device is situated away from the transport device by a distance smaller than a length of a minimum sheet in a transport direction, said double feed detection device detecting the double feed while the sheet is being held by the separating device and the transport device.

19. A method of detecting a double feed of sheets, comprising:

detecting a length of a sheet in a transport direction,

detecting an overlapping of sheets to judge the double feed while the sheet is being transported,

measuring a transport length of the sheet from a leading edge of the sheet to a trailing edge of the sheet while the sheet is being transported,

comparing the length of the sheet with the transport length, and

judging an erroneous transport of the sheet based on the comparison and the judgment of the double feed.

20. A method according to claim 19, wherein in judging the erroneous transport, the erroneous transport is judged when the transport length is larger than the length of the sheet or the double feed is judged.