Document Feeder

Abstract

A document feeder includes a conveying path extended from a document supplying position to a reading position, a first conveying roller pair provided upstream from the reading position and nipping and conveying the document, a second conveying roller pair provided downstream from the reading position and nipping and conveying the document faster than the first conveying roller pair, a post-reading conveying path extended downstream from a nipping position of the second conveying roller pair, the post-reading conveying path being located above a plane tangent to the second conveying roller pair at the nipping position running in a reverse sheet feed direction, and a third conveying roller pair provided on the post-reading conveying path and nipping and conveying the document conveyed from the second conveying roller pair at a conveying force equivalent to that of the second conveying roller pair.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing an image reading device according to an aspect of the present invention;

FIG. 2 is a longitudinal sectional view of the image reading device;

FIG. 3 is an enlarged view showing an intersecting position;

FIG. 4 is an enlarged view showing a connecting position;

FIG. 5 is an enlarged view showing a first front sensor;

FIG. 6 is a block diagram showing a control portion;

FIG. 7 is a flowchart showing the process of reading images on both sides of the document by the image reading device;

FIG. 8 is a pattern diagram showing motions of reading images in a double-sided reading mode;

FIG. 9 is a pattern diagram showing motions of reading images in the double-sided reading mode;

FIG. 10 is a pattern diagram showing motions of reading images in the double-sided reading mode;

FIG. 11 is a pattern diagram showing motions of reading images in the double-sided reading mode;

FIG. 12 is a pattern diagram showing motions of reading images in the double-sided reading mode;

FIG. 13 is a pattern diagram showing motions of reading images in the double-sided reading mode;

FIG. 14 is a pattern diagram showing motions of reading images in the double-sided reading mode;

FIG. 15 is a pattern diagram showing document conveyance to be read for images on both sides of a document by a related automatic document feeder; and

FIG. 16 is a pattern diagram showing document conveyance to be read for images on both sides of a document by the related automatic document feeder.

Claims

1. A document feeder comprising: a conveying path which is extended from a document supplying position in a predetermined direction, curved downward so as to reverse a sheet feed direction and reaching a reading position, the conveying path guiding a document from the reading position to a reverse sheet feed direction which is opposed to the sheet feed direction;a first conveying roller pair which is provided upstream in the sheet feed direction from the reading position of the conveying path and is provided above the reading position, the first conveying roller pair nipping and conveying the document passing through the conveying path;a second conveying roller pair which is provided downstream in the sheet feed direction from the reading position of the conveying path and is provided above the reading position, the second conveying roller pair nipping and conveying the document passing through the conveying path at a document conveying speed faster than the first conveying roller pair;a post-reading conveying path which is provided in the conveying path and is extended downstream from a nipping position of the second conveying roller pair, the post-reading conveying path being located above a plane tangent to the second conveying roller pair at the nipping position running in the reverse sheet feed direction; anda third conveying roller pair which is provided on the post-reading conveying path, the third conveying roller pair nipping and conveying the document conveyed from the second conveying roller pair at a conveying force equivalent to that of the second conveying roller pair.

2. The document feeder according to claim 1, wherein the third conveying roller pair is rotated at a peripheral speed equivalent to that of the second conveying roller pair.

3. The document feeder according to claim 1, wherein the third conveying roller pair holds the document at a nipping pressure lower than that of the second conveying roller pair.

4. The document feeder according to claim 1, wherein a conveying route from the first conveying roller pair on the conveying path reaching the third conveying roller pair is substantially in a shape of an S when viewed in a longitudinal direction.

5. The document feeder according to claim 1, wherein the post-reading conveying path is extended above the document supplying position.

6. The document feeder according to claim 1, wherein the third conveying roller pair conveys documents in a switchback manner.

7. The document feeder according to claim 6, wherein the post-reading conveying path has an opening at a dead end outside the document feeder, andwherein the third conveying roller pair conveys the document to an outside of the document feeder such that a part of the document projects outside from the opening, andwherein the third conveying roller conveys the document in the switchback manner.

8. The document feeder according to claim 7, wherein the third conveying roller pair conveys the document at least a part of which projects outside from the opening and deflects downward in the switchback manner.

9. The document feeder according to claim 1, wherein the conveying path is opposed to the reading position, andwherein the conveying path has a reading guide elastically urged so as to retreat from the reading position.

10. A document feeder comprising: a conveying path which is extended from a document supplying position in a predetermined direction, curved downward so as to reverse a sheet feed direction and reaching a reading position, the conveying path guiding a document from the reading position to a reverse sheet feed direction which is opposed to the sheet feed direction;a first conveying roller pair which is provided upstream in the sheet feed direction from the reading position of the conveying path and is provided above the reading position, the first conveying roller pair nipping and conveying the document passing through the conveying path;a second conveying roller pair which is provided downstream in the sheet feed direction from the reading position of the conveying path and is provided above the reading position, the second conveying roller pair nipping and conveying the document passing through the conveying path at a document conveying speed faster than the first conveying roller pair;a post-reading conveying path which is provided in the conveying path and is extended downstream from a nipping position of the second conveying roller pair in a direction having a slope relative to a horizontal plane, the slope being as large as a slope of a line which is tangent to the second conveying roller pair at the nipping position running in the reverse sheet teed direction relative to the horizontal plane; anda third conveying roller pair which is provided on the post-reading conveying path, the third conveying roller pair nipping and conveying the document conveyed from the second conveying roller pair at a conveying force equivalent to that of the second conveying roller pair.