US20090008860A1

US20090008860A1 - Automatic document feeder having document size detecting device

Info

Publication number: US20090008860A1
Application number: US11/952,840
Authority: US
Inventors: Hsi-Yu Chen
Original assignee: Primax Electronics Ltd
Current assignee: Primax Electronics Ltd
Priority date: 2007-07-06
Filing date: 2007-12-07
Publication date: 2009-01-08
Also published as: JP2009012978A; TW200902419A; TWI333931B

Abstract

The present invention relates to an automatic document feeder having a document size detecting device. The document size detecting device includes a first paper guide plate, a second paper guide plate, a first elongated perforation, a second elongated perforation, a rack movement mechanism and a plurality of sensing members. The first paper guide plate includes a first paper stopping slice, a first rack and a rib, wherein the rib is disposed on the bottom of the paper input tray. The second paper guide plate includes a second paper stopping slice and a second rack. By moving the first paper guide plate to have the rib located between an optical emitter and an optical receiver of a specified sensing member, the size of the document placed on the paper input tray is realized.

Description

FIELD OF THE INVENTION

The present invention relates to an automatic document feeder, and more particularly to an automatic document feeder having a document size detecting device.

BACKGROUND OF THE INVENTION

Generally, an automatic document feeder is used with for example a scanning apparatus for successively feeding many documents at a time. Since A4-sized documents are the most frequently used, the paper input tray and the eject tray of the common automatic document feeder are designed to accommodate A4-sized documents therein. In a case that only A4-sized documents need to be transported by the automatic document feeder, it is not necessary to include a document size detecting device in the automatic document feeder. As known, the automatic document feeder which is able to transport A3-sized documents may be used to transport the A4-sized documents because the area of the A3-sized document is two times as much as the A4-sized document. Under this circumstance, the A4-sized documents may be transported in the width direction. For discriminating whether the document to be transported by the automatic document feeder are A3-sized documents or A4-sized documents, the document size detecting device is required. Similarly, for transporting documents of various other sizes, for example those of sizes A5, B4, B6, etc., the automatic document feeder should contain a document size detecting device.
In Taiwanese Patent Gazette No. 588545, an automatic document feeder having a document size detecting device is disclosed. FIG. 1 is a schematic perspective view illustrating the automatic document feeder having a document size detecting device as disclosed in Taiwanese Patent Gazette No. 588545. As shown in FIG. 1, the automatic document feeder has a first paper guide unit 14 and a second paper guide unit 16 on bilateral sides of a paper input tray 10 of the automatic document feeder. The first paper guide unit 14 and the second paper guide unit 16 may be moved in the direction close to or far from each other. The paper input tray 10 has a paper supporting surface 13 for placing paper sheets thereon. The first paper guide unit 14 and the second paper guide unit 16 are protruded from the paper supporting surface 13. The opposite side of the paper supporting surface 13 is also referred as the bottom 15 of the paper input tray 10. The document size detecting device is arranged on the bottom 15 of the paper input tray 10.
Please refer to FIG. 2, which is a schematic partial enlarged view illustrating the document size detecting device disclosed in Taiwanese Patent No. 588545. The document size detecting device 20 is arranged on the bottom 15 and principally includes a sensing module 30, a first channel 33, a second channel 35, a third channel 37 and a plurality of ribs 42. The ribs 42 are moved with movement of the first paper guide unit 14. The sensing module 30 includes a first sensor set 32, a second sensor set 34 and a third sensor set 36. The first sensor set 32 is composed of two first sensors 32A and 32B, which are disposed on both sides of the first channel 33. The second sensor set 34 is composed of two second sensors 34A and 34B, which are disposed on both sides of the second channel 35. The third sensor set 36 is composed of two third sensors 36A and 36B, which are disposed on both sides of the third channel 36.
When a document (not shown) is placed in the paper input tray 10 (as shown in FIG. 1), the first paper guide unit 14 and the second paper guide unit 16 are moved to proper positions according to the size of the document such that the document may lie flat on the paper supporting surface 13 of the paper input tray 10. During the process of moving the first paper guide unit 14, the ribs 42 are also moved along with the first paper guide unit 14. That is, the positions of the first paper guide unit 14 and the ribs 42 are varied according to the size of the document. Since the ribs 42 are movable, the distances of the ribs 42 relative to the multiple channels 33, 35 and 37 are diverse. The document size detecting device 20 (as shown in FIG. 1) may discriminate the size of the document by judging the diverse situations whether the ribs 42 enter the channels.
Hereinafter, the operation principles of discriminating the document size will be illustrated as follows. First of all, the high-level logic value “1” and the low-level logic value “0” of a digital signal are used as indexes to indicate a conduction state and an interruption state, respectively. The definitions of the conduction state and the interruption state are written in the document size detecting device 20. In a case that all ribs 42 have not been moved into the first channel 33, the second channel 35 and the third channel 37, it is meant that the first sensor set 32, the second sensor set 34 and the third sensor set 36 of the sensing module 30 are not shielded by the ribs 42 and are all at the conduction states. Under this circumstance, a three-bit digital signal (1, 1, 1) is obtained by the document size detecting device 20.
In another case that the first sensor set 32 is sheltered by one of the ribs 42 but the second sensor set 34 and the third sensor set 36 of the sensing module 30 are not shielded by the ribs 42, the first sensor set 32 is at the interruption state but the second sensor set 34 and the third sensor set 36 are at the conduction states. Under this circumstance, a three-bit digital signal (0, 1, 1) is obtained by the document size detecting device 20. The rest may be deduced by analogy. Since eight (i.e. 2³=8) different digital signals are obtained, this document size detecting device 20 can determine eight types of documents with different sizes.
The conventional document size detecting device 20, however, still has some drawbacks. For example, the structure of the document size detecting device 20 is very complicated. In addition, it is necessary to define the relationships between the three-bit digital signals and the document types. Therefore, the digital circuit of the document size detecting device 20 is also complicated and not cost-effective.
In views of the above-described disadvantages resulted from the prior art, the applicant keeps on carving unflaggingly to develop an automatic document feeder having a document size detecting device according to the present invention through wholehearted experience and research.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an automatic document feeder having a document size detecting device, and more particularly to provide an automatic document feeder having a simplified document size detecting device.
In accordance with an aspect of the present invention, there is provided an automatic document feeder having a document size detecting device. The automatic document feeder further includes a paper input tray for placing a document thereon. The document size detecting device includes a first paper guide plate, a second paper guide plate, a first elongated perforation, a second elongated perforation, a rack movement mechanism and a plurality of sensing members. The first paper guide plate includes a first paper stopping slice for positioning the document on a surface of the paper input tray, a first rack on a bottom of the paper input tray, and a rib on the bottom of the paper input tray. The second paper guide plate includes a second paper stopping slice for positioning the document on the surface of the paper input tray and a second rack on the bottom of the paper input tray. The first elongated perforation is formed in the paper input tray. The first paper guide plate is partially penetrated through the first elongated perforation such that the first paper stopping slice is disposed on the surface of the paper input tray and the first rack and the rib are disposed on the bottom of the paper input tray. The second elongated perforation is formed in the paper input tray. The second paper guide plate is partially penetrated through the second elongated perforation such that the second paper stopping slice is disposed on the surface of the paper input tray and the second rack is disposed on the bottom of the paper input tray. The rack movement mechanism is engaged with the first rack and the second rack such that the first paper guide plate and the second paper guide plate are movable along the first elongated perforation and the second elongated perforation, respectively. The sensing members are disposed under the bottom of the paper input tray and have respective optical emitters and respective optical receivers. The rib is moved with movement of the first paper guide plate to a selected location between the optical emitter and the optical receiver of a specified sensing member, thereby realizing the size of the document.
In an embodiment, the first paper stopping slice, the first rack and the rib of the first paper guide plate are integrally formed into one-piece.
In an embodiment, the second paper stopping slice and the second rack of the second paper guide plate are integrally formed into one-piece.
In an embodiment, the rack movement mechanism includes a gear, a rotating disc and a rotating shaft.
The above objects and advantages of the present invention will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed description and accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view illustrating the automatic document feeder having a document size detecting device as disclosed in Taiwanese Patent No. 588545;

FIG. 2 is a schematic partial enlarged view illustrating the document size detecting device disclosed in Taiwanese Patent No. 588545;

FIG. 3 is a schematic perspective view of an automatic document feeder according to a preferred embodiment of the present invention;

FIG. 4 is a schematic partial enlarged view illustrating the document size detecting device of the present invention;

FIG. 5 is a schematic partial perspective view illustrating the detailed structure of the rack movement mechanism;

FIG. 6 is a schematic partial perspective view of the document size detecting device taken from the rear side; and

FIG. 7 is a schematic partial perspective view of a document size detecting device taken from the rear side according to another preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In views of the above-described disadvantages resulted from the prior art, the present invention provides an automatic document feeder having a document size detecting device. Referring to FIG. 3, a schematic perspective view of an automatic document feeder according to a preferred embodiment of the present invention is illustrated. The automatic document feeder 100 has a paper input tray 140. The paper input tray 140 has a surface 1401 for placing thereon a document (not show). In addition, a document size detecting device 110 is mounted in the paper input tray 140. The document size detecting device 110 principally includes a first paper guide plate 120, a second paper guide plate 130, a rack movement mechanism (not shown) and a plurality of sensing members (not shown). The first paper guide plate 120 includes a first paper stopping slice 1201, a first rack 1202 and a rib (not shown). The second paper guide plate 130 includes a second paper stopping slice 1301 and a second rack 1302. In addition, a first elongated perforation 150 and a second elongated perforation 160 are formed in the surface 1401 of the paper input tray 140.
In this embodiment, the first paper stopping slice 1201, the first rack 1202 and the rib of the first paper guide plate 120 are integrally formed into one-piece, and the second paper stopping slice 1301 and the second rack 1302 of the second paper guide plate 130 are also integrally formed into one-piece. The first paper guide plate 120 is partially penetrated through the first elongated perforation 150 such that the first paper stopping slice 1201 is disposed on the surface 1401 of the paper input tray 140 and the first rack 1202 and the rib are disposed on the bottom of the paper input tray 140. The second paper stopping slice 1301 is partially penetrated through the second elongated perforation 160 such that the second paper stopping slice 1301 is disposed on the surface 1401 of the paper input tray 140 and the second rack 1302 is disposed on the bottom of the paper input tray 140. The first rack 1202 and the second rack 1302, which are disposed on the bottom of the paper input tray 140, are engaged with the rack movement mechanism. By means of the rack movement mechanism, the first paper stopping slice 1201 and the second paper stopping slice 1301 are movable on the paper input tray 140, thereby properly placing various types of documents having different sizes on the paper input tray 140.
FIG. 4 is a schematic partial enlarged view illustrating the document size detecting device of the present invention. As can be seen in FIG. 4, the first paper stopping slice 1201, the first rack 1202 and the rib 1203 of the first paper guide plate 120 are integrally formed into one-piece. The first rack 1202 is engaged with the rack movement mechanism 170. The rack movement mechanism 170 includes a gear (not shown), a rotating disc 1702 and a rotating shaft 1703. Please refer to FIG. 4 again. The document size detecting device includes two sensing members 180 and 181. The first sensing member 180 includes a first optical emitter 1801 and a first optical receiver 1802. The second sensing member 181 includes a second optical emitter 1811 and a second optical receiver 1812. The light beams emitted from the optical emitters 1801 and 1811 may be received by the optical receivers 1802 and 1812, respectively.
FIG. 5 is a schematic partial perspective view illustrating the detailed structure of the rack movement mechanism 170. The rack movement mechanism 170 is disposed on the bottom 1402 of the paper input tray 140. The gear 1701 of the rack movement mechanism 170 is engaged with the first rack 1202 and the second rack 1302. Since the gear 1701 is engaged with the first rack 1202 and the second rack 1302, the second paper guide plate 130 is synchronously moved when the first paper guide plate 120 is moved by the user. The gear 1701 is fixed by the rotating disc 1702. The gear 1701 and the rotating disc 1702 are sheathed around the rotating shaft 1703 such that the rack movement mechanism 170 is fixed on the bottom 1402 of the paper input tray 140.
FIG. 6 is a schematic partial perspective view of the document size detecting device taken from the rear side. In this embodiment, the document size detecting device 110 may detect A4-sized documents and A3-sized documents. As shown in FIG. 3, the first paper guide plate 120 is partially penetrated through the first elongated perforation 150 such that the first paper stopping slice 1201 is disposed on the surface 1401 of the paper input tray 140 and the first rack 1202 and the rib 1203 are disposed on the bottom of the paper input tray 140. The first rack 1202 and the second rack 1302 are engaged with the rack movement mechanism 170. By means of the rack movement mechanism 170, the first paper guide plate 120 and the second paper guide plate 130 are synchronously moved. The first sensing member 180 and the second sensing member 181 are disposed under the bottom 1402 of the paper input tray 140. In the first sensing member 180, the light beam emitted from the first optical emitter 1801 is received by the first optical receiver 1802. Likewise, in the second sensing member 181, the light beam emitted from the second optical emitter 1811 is received by the second optical receiver 1812. The first sensing member 180 and the second sensing member 181 are used to detect the A3-sized documents and A4-sized documents, respectively. The locations of the sensing members are determined according to the sizes of the documents to be transported by the automatic document feeder. For example, the distance between the first paper guide plate 120 and the second paper guide plate 130 is adjusted to be approximately equal to the width of the A3-sized document (e.g. 297 mm) in order to detect the A3-sized document. As a consequence, the first sensing member 180 is disposed under the rib 1203 of the first paper guide plate 120 and the rib 1203 is located between the first optical emitter 1801 and the first optical receiver 1802 of the first sensing member 180. Alternatively, the document size detecting device 110 may include other sensing members, and the above concepts may be applied to these sensing members for detecting other types of documents of different sizes.
Hereinafter, the operations of the document size detecting device 110 will be illustrated as follows. First of all, the user may move the first paper guide plate 120 to adjust the distance between the first paper guide plate 120 and the second paper guide plate 130 to be approximately equal to the width of the document to be transported by the automatic document feeder. Then, the document is placed on the surface 1401 of the paper input tray 140 and between the first paper guide plate 120 and the second paper guide plate 130. In a case that the document is A3-sized for example, the rib 1203 of the first paper guide plate 120 is moved to the location between the first optical emitter 1801 and the first optical receiver 1802 of the first sensing member 180. As a consequence, the light beam emitted from the first optical emitter 1801 is shielded by the rib 1203 and fails to be received by the first optical receiver 1802. Under this circumstance, the first optical receiver 1802 will output a signal indicative of an A3-sized document such that the document size detecting device 110 may realize the actual size of the document to be transported by the automatic document feeder.
FIG. 7 is a schematic partial perspective view of a document size detecting device taken from the rear side according to another preferred embodiment of the present invention. The document size detecting device 110 of this embodiment may discriminate three types of documents, e.g. A3-sized documents, A4-sized documents and A5-sized documents. The document size detecting device includes three sensing members 180, 181 and 182. The first sensing member 180 includes a first optical emitter 1801 and a first optical receiver 1802 for detecting the A3-sized documents. The second sensing member 181 includes a second optical emitter 1811 and a second optical receiver 1812 for detecting the A4-sized documents. The third sensing member 182 includes a third optical emitter 1821 and a third optical receiver 1822 for detecting the A5-sized documents. The principle of detecting the A3-sized documents by the first sensing member 180 has been illustrated above, and is not redundantly described herein. In a case that the document to be transported is A4-sized, the distance between the first paper guide plate 120 and the second paper guide plate 130 is adjusted to be approximately equal to the width of the A4-sized document (e.g. 210 mm). As a consequence, the second sensing member 181 is disposed under the rib 1203 of the first paper guide plate 120 and the rib 1203 is located between the second optical emitter 1811 and the second optical receiver 1812 of the second sensing member 181. In a case that the document to be transported is A5-sized, the distance between the first paper guide plate 120 and the second paper guide plate 130 is adjusted to be approximately equal to the width of the A5-sized document (e.g. 148 mm). As a consequence, the third sensing member 182 is disposed under the rib 1203 of the first paper guide plate 120 and the rib 1203 is located between the third optical emitter 1821 and the third optical receiver 1822 of the third sensing member 182.
As previously described, the conventional document size detecting device is very complicated in its structure and its digital circuitry system. In comparison with prior art, the structure of the present document size detecting device is simplified. By moving the rib of the paper guide plate to a predetermined location to hinder the light beam from being received by a corresponding light receiver, the actual size of the document to be transported by the automatic document feeder is realized. Moreover, instead of configuring multiple channels, only a path is required for moving the rib therein. Since more than three sensing members are arranged along the path, the document size detecting device of the present invention may detect diverse types of documents with different sizes. Since the locations of the sensing members may be changed according to the user's requirement, the applications of the document size detecting device are very flexible and broad. Without the need of the complicated digital circuit, the document size detecting device of the present invention can realize the actual size of the document by discriminating which optical sensor has not received the light beam. Consequently, the present invention is very cost-effective.
While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not be limited to the disclosed embodiment. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.

Claims

1. An automatic document feeder having a document size detecting device, said automatic document feeder including a paper input tray for placing a document thereon, and said document size detecting device comprising:

a first paper guide plate including a first paper stopping slice for positioning said document on a surface of said paper input tray, a first rack on a bottom of said paper input tray, and a rib on said bottom of said paper input tray;

a second paper guide plate including a second paper stopping slice for positioning said document on said surface of said paper input tray and a second rack on said bottom of said paper input tray;

a first elongated perforation formed in said paper input tray, wherein said first paper guide plate is partially penetrated through said first elongated perforation such that said first paper stopping slice is disposed on said surface of said paper input tray and said first rack and said rib are disposed on said bottom of said paper input tray;

a second elongated perforation formed in said paper input tray, wherein said second paper guide plate is partially penetrated through said second elongated perforation such that said second paper stopping slice is disposed on said surface of said paper input tray and said second rack is disposed on said bottom of said paper input tray;

a rack movement mechanism engaged with said first rack and said second rack such that said first paper guide plate and said second paper guide plate are movable along said first elongated perforation and said second elongated perforation, respectively; and

a plurality of sensing members disposed under said bottom of said paper input tray and having respective optical emitters and respective optical receivers, wherein said rib is moved with movement of said first paper guide plate to a selected location between said optical emitter and said optical receiver of a specified sensing member, thereby realizing the size of said document.

2. The automatic document feeder having a document size detecting device according to claim 1 wherein said first paper stopping slice, said first rack and said rib of said first paper guide plate are integrally formed into one-piece.

3. The automatic document feeder having a document size detecting device according to claim 1 wherein said second paper stopping slice and said second rack of said second paper guide plate are integrally formed into one-piece.

4. The automatic document feeder having a document size detecting device according to claim 1 wherein said rack movement mechanism includes a gear, a rotating disc and a rotating shaft.