This application claims the benefit under 35 U.S.C. §119(a) of Korean Patent Application No. 2003-57280, filed on Aug. 19, 2003, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety.
1. Field of the Invention
The present invention relates to an automatic document feeder (ADF). More particularly, the present invention relates to an ADF that conveys a document toward a scanning region in a multi-functional office machine.
2. Description of the Related Art
Multi-function devices having a copying function such as a copier and a facsimile typically include an automatic document feeder (ADF). Individual sheets of multiple page documents can be supplied one by one automatically without opening and closing a platen cover that covers a copying region using the ADF, thus reducing time required for a copying or scanning operation.
Referring to
A scanning device 1 such as a scanner or a copying machine is typically disposed below the ADF 10, and a glass plate 2 is disposed on an upper portion of the scanning device 1. An image device 3 is disposed under the glass plate 19 and scans a recording surface of the document. A lower surface of the ADF 10 functions as a platen cover 10a that covers the glass plate 2 of the scanning device 1.
When the ADF 10 is in use, the image device 3 performs a scanning operation from the recording surface of the document when the document is passed between the glass plate 19 and the white block 20 by the ADF 10. When the ADF 10 is not in use, and a user opens the platen cover 10a, places the document on the glass plate 2, and closes the platen cover 10a to scan the document, the image device 3 performs the scanning operation by moving along the direction of arrow A in
When the pickup roller 12 rotates in response to a motor (not shown) in the ADF 10, the uppermost sheet contacting the pickup roller 12 among the documents stacked on the input tray 11 is picked up and pushed into the document conveying path. The sheet contacted by the separation roller 13 on the document conveying path enters into the document conveying path. If two or more sheets are picked up, only the uppermost document is allowed to enter the document conveying path because of the friction pad 14. The document is guided by the inner and outer curved guides 15 and 16. The document passes between the inner and outer curved guides 15 and 16 by the convey roller 17 and enters the scanning region. The document is scanned by the image device 3, which is located under the glass plate 19 at the scanning region, and then discharged out of the ADF 10 by the discharge roller 25 after passing through the guide plates 23 and 24. The document is then discharged onto the output tray 27. On the other hand, in the conventional ADF 10, a curved section of the document conveying path is inevitably generated, and a curvature of the curved section is reduced in order to reduce the size of the ADF 10. Also, a linear velocity of the convey roller 17 is faster than that of the separation roller 13, and thus the document is smoothly moved between the inner and outer curved guides 15 and 16.
However, because the linear velocity of the convey roller 17 is faster than that of the separation roller 13, the document between the convey roller 17 and the separation roller 13 is in a stressed state, and the document adheres to a surface of the inner curved guide 15 when passing between the inner and outer curved guides 15 and 16. Since the document is affected by a frictional force of the inner curve guide 15, the document conveying operation is not performed uniformly. Therefore, a length of the document image scanned on the scanning region may be changed.
In order to solve the above problem, an additional convey roller and pinch roller can be installed at the curve guides 15 and 16, however, the operation becomes complex, and the curvatures of the curve guides 15 and 16 must be increased due to the additional rollers, thus increasing the size of the ADF 10.
The present invention provides an automatic document feeder (ADF) that improves image quality by reducing a frictional force between a curved guide and a document in order to maintain a constant feeding speed of the documents.
According to an aspect of the present invention, there is provided an automatic document feeder including a separation roller that receives the document from the pickup roller and pushes the document into a document conveying path; an inner curved guide and an outer curved guide that are semicircular and change a conveying direction of the document conveyed by the separation roller along the document conveying path; a convey roller, which conveys the document, installed on the inner curved guide; at least one idle roller that is rotatably installed at the inner curved guide in order to facilitate motion of the document between the separation roller and the convey roller; a glass plate forming a scanning region over which the document passes after passing between the inner and outer curved guides; and a discharge roller that discharges the document after passing over the scanning region.
The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which:
Hereinafter, an automatic document feeder according to a exemplary embodiment of the present invention will be described in detail. Thicknesses of layers or sections shown in the drawings are exaggerated for clarity.
Referring to
When the document is transmitted by the ADF 110, the image device 103 scans a recording surface of the document when the document is passed between the glass plate 119 and the white block 120 by the ADF 110. When a document is manually placed onto the glass 102 to be scanned without using the ADF 110, a user opens the platen cover 110a, places the document on the glass plate 102, closes the platen cover 110a to scan the document, and the image device 103 performs the scanning operation by moving along the direction of arrow A in
Referring to
The inner and outer curved guides 115 and 116 have a predetermined curvature. The idle roller 130 is disposed at the document conveying path between the convey roller 117 and the separation roller 113 and ensures that the document proceeds with an evenly distributed stress by reducing the frictional force the document passing between the convey roller 117 and the separation roller 113.
The idle roller 130 is installed at the hole 115a, however, a recess (not shown) having a same shape as the hole 115a may be formed in the inner curved guide 115, and the idle roller 130 may be installed in the recess.
Operations of the ADF 110 having the above described structure will now be described with reference to
When the pickup roller 112 rotates in response to a motor (not shown), an uppermost sheet contacting the pickup roller 112 among the documents mounted on the input tray 111 is picked up and pushed into the document conveying path. The document contacting the pickup roller 112 is conveyed along the document conveying path by the separation roller 113. If two or more sheets are picked up, sheets below the uppermost sheet are prevented from entering the document conveying path by the friction pad 114. The document is guided along the document conveying path by the inner and outer curved guides 115 and 116. The document is conveyed between the curve guides 115 and 116 by the separation roller 113 toward the convey roller 117 and the pinch roller 118. If a linear velocity of the convey roller 117 is faster than that of the separation roller 113, the document between the convey roller 117 and the separation roller 113 is in a stressed state, and a surface of the document advantageously contacts the idle roller 130 rather than the surface of the inner curved guide 115. Since the idle roller 130 rotates with the document, the document can pass through the inner and outer curved guides 115 and 116 at a constant speed without experiencing a frictional force due to contact with the inner guide place 115 and enter the scanning region. The document is scanned by the image device 103 under the glass plate 119, passes between the guide plates 123 and 124, and is discharged out of the ADF 110 by the discharge roller 125 and discharged onto the output tray 127.
Referring to
The idle rollers 230 are disposed along the document conveying path between the convey roller 117 and the separation roller 113 and ensure that the document proceeds with an evenly distributed stress by reducing the frictional force between the document and the inner curved guide 115.
As described above, the ADF according to an embodiment of the present invention reduces the frictional force between the inner surface of the curve guide and the document while maintaining the tensed state of the document between the convey roller and the separation roller, thus allowing the document to proceed toward the scanning region with a constant speed and improving a the scanning quality. Also, the curvatures of the curved guides can be reduced, thus reducing the size of the ADF.
While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.
Number | Date | Country | Kind |
---|---|---|---|
2003-57280 | Aug 2003 | KR | national |