DE29512776U1 - Automatic document feeder for an image forming device - Google Patents

Description

August 8, 1995 ACER PERIPHERALS, INC. L22293 Al/Le/cp

AUTOMATIC DOCUMENT FEEDER &iacgr;&ogr; FOR AN IMAGE FORMING DEVICE

The invention relates to an automatic document feeder (ADF) used in an image forming apparatus, and more particularly to an ADF which can selectively output the original documents in an order and a reverse order.

An ADF is used extensively with a copier or similar imaging device, such as a scanner, for automatically and sequentially feeding a plurality of documents with an image thereon into a scanning position. At the scanning position, the document is illuminated to reproduce an image of it on a medium, such as a sheet of paper or transparency.

There are two types of ADF in the market regarding the document path. The first type is the so-called straight path and the other type is the U-shaped path. The straight path is more suitable for documents of different thicknesses. However, after scanning a large number of documents in a sequential or normal page order, the order of the pages of the output document from the output of the ADF is reversed compared to the original sequential or normal order. While the U-shaped path type ADF outputs the documents in the same page order as the

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original document stacked in the paper tray of the ADF, it is more suitable for documents of thinner thickness. This means that jamming of documents of thicker sheet thickness often occurs when a U-shaped path type ADF is used.

Since none of the conventional ADFs are capable of transferring the documents in either a straight path mode or a U-shaped path mode as desired by the user, the need has arisen for the ADFs to be able to operate in both of the modes described above.

It is therefore an object of the invention to provide an ADF for an image forming apparatus which can operate in the two modes described above.

It is a further object of the invention to provide a generally improved ADF for an image forming apparatus.

According to the invention, an automatic document feeder (ADF) used for an image forming apparatus automatically and sequentially feeds a plurality of documents having images thereon from a paper cassette to an illumination position of the image forming apparatus, with the uppermost document of the plurality of documents being fed first. The plurality of documents are arranged and stacked in the paper cassette selectively in a sequential or normal page order or a reverse page order. The ADF has a first document path, a second document path and a path selection device. The first document path directs the documents to the illumination position.

tion and outputs the plurality of documents after being illuminated to a first document outlet of the ADF such that the output documents are stacked in the reverse page order when the plurality of documents are stacked in the normal page order in the paper cassette. The second document path directs the documents to the illumination position and outputs the plurality of documents after being illuminated to a second document outlet of the ADF such that the output documents are stacked in the normal page order,

‘ when the plurality of documents are stacked in the normal page order in the paper tray. The path selecting device selects between the first and second document paths.

Further advantages, features and possible applications of the invention will now be explained in detail using an embodiment with reference to the drawings.

Show it:

Fig. 1 is a perspective view of an ADF applied and interacting with a flatbed scanner;

Fig. 2 is a view showing the components of the device according to the invention and the operation in the straight path mode;

Fig. 3 is a view showing the components of the device according to the invention and the operation in a U-shaped path mode; and

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Fig. 4 is a perspective view of the transport roller 30 in Fig. 2 or Fig. 3.

As shown in Fig. 1, the ADF 11 according to the invention is generally arranged above a platen provided in a flatbed scanner device 13 and can be opened away from the platen.

Referring to Fig. 2, the present invention comprises a first

&iacgr;&ogr; document path defined by a pick-up roller 22, transport rollers 23, transport rollers 25, 26, 30 and output rollers 27. The document is guided through the first document path indicated by the arrow when the path selector 24 is set to guide the document which is fed from the roller nip

is transported downward between the rollers 23 as shown in Fig. 2. The documents are first arranged and stacked in the cassette 50 prior to the scanning operation. When the operation begins, the top sheet of the documents in the stack is fed into the interior space of the ADF through the nip between the pickup rollers 22 and the cooperating guide surface. Thereafter, the document passes through the nip between the transport rollers 23 and enters the nip between the rollers 30 and 25 by the guidance of the lower surface of the selector 24 and the guide surface 21. After the document has passed the scanning position 40, which is located below the roller 30, the document passes through the nip between the rollers 30 and 26. As the selector 28 is activated to create a bias through a small angle in the counterclockwise direction, which closes the channel formed between the inner surface of the selector 28 and the roller 30, the document passes through

the nip between the output rollers 27 and is then output to the exterior of the ADF housing. Note that when the straight path mode is selected, the documents stacked in the cassette 50 must be arranged in a face down orientation such that the image thereon can be scanned at the scanning location 40. Note further that the page order is reversed from the original page order when the straight path mode is selected.

&iacgr;&ogr; Referring to Fig. 3, the apparatus according to the invention comprises a second document path defined by a pickup roller 22, transport rollers 23, transport rollers 29, 30, a selector 28, transport rollers 26, 25, a guide surface 21 and output rollers 20. The document is fed through the second document path,

is indicated by the arrow when the path selector 24 is set to guide the document being transported upward from the nip between the rollers 23 as shown in Fig. 3. The documents are arranged and stacked in the cassette 50 prior to the scanning operation. When the operation begins, the top sheet of the documents in the stack is fed into the interior space of the ADF through the nip between the pickup roller 22 and the cooperating guide surface. Thereafter, the document passes through the nip between the transport rollers 23 and enters the nip between the rollers 30 and 29 through the guide of the upper surface of the selector 24. Thereafter, the document passes through the channel between the selector 28 and the roller 30, the nip between the roller 26 and the roller 30 and enters the scanning position 40 which is located below the roller 30.

After the document passes the scanning position 40, it passes through the nip between the rollers 30 and 25. Thereafter, the document passes through the nip between the output rollers 30 through the guide of the guide surface 21 and is output to the exterior of the housing of the ADF 11. It is to be understood that when a U-shaped path mode is selected, the stacked documents in the cassette 50 must be arranged in a face-up orientation such that the image thereon can be scanned at the scanning location 40. It is further noted that the same page order

&iacgr;&ogr; such as that in the document cassette 50 when the U-shaped path mode is selected.

Fig. 4 is intended to show that the transport rollers 30 are spaced apart along their axes of rotation such that the spaces therebetween accommodate the ends of the selector 28 when the machine is operating in a straight path mode or accommodate the ends of associated paper guide plates.

Claims (1)

August 8, 1995 ACER PERIPHERALS, INC. L22293 Al/Le/cp CLAIM &iacgr;&ogr; Automatic document feeder (ADF) for use with an image forming apparatus for automatically feeding a plurality of documents having images thereon from a paper cassette to an illumination position of the image forming apparatus in a sequential manner, the uppermost document of the plurality of documents being fed first is fed and the plurality of documents which are arranged and stacked in the paper cassette optionally in a sequential order or a reverse order, the ADF comprising: a first document path for guiding the documents to the illumination position and for outputting the plurality of documents after being illuminated to a first document outlet of the ADF such that the output documents are stacked in the reverse order when the plurality of documents are stacked in the sequential page order in the paper cassette; a second document path for guiding the documents to the illumination position and for outputting the plurality of documents, after being illuminated, to a second document outlet of the ADF such that the output documents are stacked in the sequential page order when the plurality of documents are stacked in the sequential page order in the paper cassette; and a path selection device for selecting between the first and second document paths.