Paper-feeding mechanism of automatic document feeder

A paper-feeding mechanism of an automatic document feeder includes a pick-up module, a supporting module and a paper stopping module. The pick-up module is used for picking an uppermost paper sheet from the stack of paper sheets and transporting the uppermost paper sheet into a passageway inside the automatic document feeder. The supporting module supports the pick-up module and is rotated to either ascend or descend the pick-up module, wherein the supporting module has a sustaining part on a sidewall thereof. When the supporting module and the pick-up module are downwardly rotated, the stopping plate is moved vertically to a paper-feeding position for allowing the uppermost paper sheet to be transported into the passageway. When the supporting module and the pick-up module are upwardly rotated, the stopping plate is moved vertically to a paper-stopping position for hindering the uppermost paper sheet from being transported into the passageway.

FIELD OF THE INVENTION

The present invention relates to a paper-feeding mechanism, and more particularly to a paper-feeding mechanism of an automatic document feeder.

BACKGROUND OF THE INVENTION

With increasing power of personal computers, a diversity of office machines can be employed with the personal computers to achieve various purposes. The diverse office machines, however, occupy lots of space. A multifunction peripheral having multiple functions in one structural unit, for example the functions of a printer, a scanner, a fax machine and/or a copy machine, is thus developed. As a consequence, the processing capability of the multifunction peripheral is increased and the operative space thereof is reduced.

Nowadays, the printer, a scanner, a fax machine, a copy machine or the multifunction peripheral usually has an automatic document feeder for successively and continuously feeding many paper sheets. After a stack of papers to be scanned are placed on the sheet input tray of the automatic document feeder, the sheet-feeding mechanism of the automatic document feeder will successively transport the paper sheets into the inner portion of the office machine so as to implement associated operations such as scanning, faxing, scanning operations and the like.

Referring toFIG. 1(a), a schematic cross-sectional view of a conventional automatic document feeder for use with an office machine is illustrated. The automatic document feeder10ofFIG. 1(a) principally includes a pick-up module11, a transfer module12, an ejection module13, a paper input tray14and a paper ejecting tray15. The office machine further includes an image processing module19and a glass platform191under the automatic document feeder10.

After a stack of paper sheets141to be scanned are placed on the paper input tray14, the pick-up module11may successively pick the uppermost paper sheets one by one into the passageway within the automatic document feeder10. Next, the paper sheet141is transported by the transfer module12across the glass platform191so that a first side of the paper sheet is scanned by the image processing module19. The paper sheet141whose first side has been scanned is then ejected to the paper ejecting tray15by the ejection module13. For a purpose of performing a duplex scanning operation, the transfer module12further includes an inverting member121adjacent to the ejection module13. After the first side of the paper sheet141has been scanned and a majority of the paper sheet141is ejected to the paper ejecting tray15, the paper sheet141is turned over by the inverting member121and then fed into the passageway. Next, the paper sheet141is transported by the transfer module12across the glass platform191so that a second side of the paper sheet is scanned by the image processing module19.

Please refer toFIG. 1(a) again. The pick-up module11includes a pick-up roller16, a separation roller17and a paper stopping module18(as is also shown inFIG. 1(b)). The pick-up roller16is driven by a driving motor (not shown) to rotate and thus the pick-up roller16is either ascended or descended. When the pick-up roller16is descended to contact with the paper sheet141, the paper sheet141is fed by the pick-up roller16. The separation roller17is rotated to separate the uppermost paper sheet141from the stack of paper sheets, thereby picking a single paper sheet to the transfer module12.

FIG. 1(b) is a schematic perspective view illustrating a paper stopping module18of the automatic document feeder10. The paper stopping module18includes a rotating shaft181, a clamp element182and a paper stopping plate183. An end of the clamp element182is sheathed around the rotating shaft181and fixed by a spring184. The stopping plate183is clamped by the other end of the clamp element182. The rotating shaft181is driven by another motor (not shown) to rotate in either a clockwise or anti-clockwise direction. Due to the change of friction force between the rotating shaft181and the clamp element182, the stopping plate183is pivotal about the rotating shaft181. When the stopping plate183is rotated to the uppermost position or the lowermost position, idle running of the motor which is connected to the rotating shaft181is rendered.

In a case that no paper-feeding instruction is received by the automatic document feeder10, the pick-up roller16is raised to a standby position. Meanwhile, the stopping plate183is correspondingly raised such that the paper sheets141on the paper input tray14are hindered from being transported into the paper feeding port.

Whereas, in a case that a paper-feeding instruction is received by the automatic document feeder10, the motor which is connected to the rotating shaft181exerts a positive driving force on the rotating shaft181. As a consequence, the rotating shaft181is rotated and the stopping plate183is rotated downwardly to the lowermost position. Meanwhile, the uppermost paper sheet may be transported into the paper feeding port without being stopped by the stopping plate183. At that moment, the pick-up roller16is driven by the driving motor and lowered to a paper-feeding position where the pick-up roller16contacts with the uppermost paper sheet141. The separation roller17is rotated to separate the uppermost paper sheet141from the stack of paper sheets, thereby picking a single paper sheet to the transfer module12.

When a sensor (not shown) of the automatic document feeder10detects that the paper sheet141reaches the separation roller17, the rotating shaft181is driven by the motor to rotate in a reverse direction and the pick-up roller16is raised to the standby position. Meanwhile, the clamp element182is also reverse rotated and the stopping plate183is correspondingly raised to stop the paper feeding port, thereby preventing the remainder paper sheets from being transported into the paper feeding port. Until the uppermost paper sheet is ejected to the paper ejecting tray15, the above procedures are repeated to successively feed the remainder paper sheets one by one.

As previously described, after the first side of the paper sheet141has been scanned and a majority of the paper sheet141is ejected to the paper ejecting tray15, the paper sheet141is turned over by the inverting member121and then fed into the passageway. Next, the paper sheet141is transported by the transfer module12across the glass platform191so that a second side of the paper sheet is scanned by the image processing module19. Conventionally, when the paper sheet141is turned over by the inverting member121and fed into the passageway, the rotating shaft181is driven by the motor to rotate and the stopping plate183is rotated downwardly to the lowermost position. As known, the procedure of rotating the stopping plate183to the lowermost position is redundant at the moment when the paper sheet141is turned over by the inverting member121and fed into the passageway, because the paper sheet141comes from the paper ejecting tray15rather than the paper input tray14. The frequent idle running of the motor for fixing the stopping plate183at the lowermost position may reduce the motor's operating life. Moreover, the use of the motor for driving the rotating shaft181increases the fabricating cost. In addition, the performance of stopping the paper sheets by the stopping plate183is usually unsatisfied. The rotation of the rotating shaft181may result in a drag force between the rotating shaft181and the clamp element182, which increases the burden of the overall system.

In views of the above-described disadvantages resulted from the conventional method, the applicant keeps on carving unflaggingly to develop a paper-feeding mechanism of an automatic document feeder according to the present invention through wholehearted experience and research.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a paper-feeding mechanism of an automatic document feeder for enhancing performance of stopping the paper sheets, reducing the fabricating cost, and minimizing the operating burden.

In accordance with an aspect of the present invention, there is provided a paper-feeding mechanism of an automatic document feeder. The paper-feeding mechanism is coupled with a casing of the automatic document feeder for successively feeding a stack of paper sheets on a paper input tray. The paper-feeding mechanism includes a pick-up module, a supporting module and a paper stopping module. The pick-up module is disposed in the vicinity of the paper input tray for picking an uppermost paper sheet from the stack of paper sheets and transporting the uppermost paper sheet into a passageway inside the automatic document feeder. The supporting module supports the pick-up module and is rotated to either ascend or descend the pick-up module, wherein the supporting module has a sustaining part on a sidewall thereof. The paper stopping module is coupled to the casing and includes a stopping plate and a transmission member. A first end of the transmission member is in contact with the sustaining part. A second end of the transmission member is coupled with the stopping plate. When the supporting module and the pick-up module are downwardly rotated, the stopping plate is moved vertically to a paper-feeding position for allowing the uppermost paper sheet to be transported into the passageway. When the supporting module and the pick-up module are upwardly rotated, the stopping plate is moved vertically to a paper-stopping position for hindering the uppermost paper sheet from being transported into the passageway.

In an embodiment, the pick-up module includes a pick-up roller and a separation roller for picking the uppermost paper sheet from the stack of paper sheets and transporting the uppermost paper sheet into a passageway.

In an embodiment, the separation roller includes a separation roller axle, and the supporting module is pivotal about the separation roller axle.

In an embodiment, the transmission member includes a contact part to be contacted with the sustaining part of the supporting module and a clamp part for clamping an upper edge of the stopping plate.

In an embodiment, a pivotal shaft is disposed at a connection region of the clamp part and the contact part, and a grasp arm is protruded from an inner surface of the casing for grasping both terminals of the pivotal shaft.

In accordance with another aspect of the present invention, there is provided an automatic document feeder. The automatic document feeder includes a casing, a paper input tray for placing a stack of paper sheets thereon, and a paper-feeding mechanism. The paper-feeding mechanism includes a pick-up module, a supporting module and a paper stopping module. The pick-up module is disposed in the vicinity of the paper input tray for picking an uppermost paper sheet from the stack of paper sheets and transporting the uppermost paper sheet into a passageway inside the automatic document feeder. The supporting module supports the pick-up module and is rotated to either ascend or descend the pick-up module, wherein the supporting module has a sustaining part on a sidewall thereof. The paper stopping module is coupled to the casing and includes a stopping plate and a transmission member. A first end of the transmission member is in contact with the sustaining part. A second end of the transmission member is coupled with the stopping plate. When the supporting module and the pick-up module are downwardly rotated, the stopping plate is moved vertically to a paper-feeding position for allowing the uppermost paper sheet to be transported into the passageway. When the supporting module and the pick-up module are upwardly rotated, the stopping plate is moved vertically to a paper-stopping position for hindering the uppermost paper sheet from being transported into the passageway.

In an embodiment, the automatic document feeder further includes a transfer module disposed in the vicinity of the paper-feeding mechanism for transporting the uppermost paper sheet fed by the paper-feeding mechanism to an image processing module.

In an embodiment, the automatic document feeder further includes an ejection module disposed in the vicinity of the transfer module for ejecting the uppermost paper sheet which has been processed by the image processing module.

In an embodiment, the automatic document feeder further includes a paper eject tray, wherein the uppermost paper sheet which has been processed by the image processing module is ejected to the paper eject tray.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring toFIG. 2(a), a schematic cross-sectional view of an automatic document feeder for use with an office machine according to a preferred embodiment of the present invention is illustrated. The automatic document feeder20principally includes a casing21, a paper-feeding mechanism22, a transfer module23, an ejection module24, a paper input tray25and a paper ejecting tray26. As shown inFIG. 2(a), the paper-feeding mechanism22is at a standby position. The office machine further includes an image processing module3and a glass platform4under the automatic document feeder20. The office machine of the present invention includes but is not limited to a printer, a scanner, a fax machine, a copy machine or a multifunction peripheral. Hereinafter, the present invention is illustrated by referring to a scanner.

After a stack of paper sheets251to be scanned are placed on the paper input tray25, the paper-feeding mechanism22may successively pick the uppermost paper sheets one by one into the passageway within the automatic document feeder20. Next, the paper sheet251is transported by the transfer module23across the glass platform4so that a first side of the paper sheet251is scanned by the image processing module3. The paper sheet251whose first side has been scanned is then ejected to the paper ejecting tray26by the ejection module24. For a purpose of performing a duplex scanning operation, the transfer module23further includes an inverting member231adjacent to the ejection module24. After the first side of the paper sheet251has been scanned and a majority of the paper sheet251is ejected to the paper ejecting tray26, the paper sheet251is turned over by the inverting member231and then fed into the passageway. Next, the paper sheet251is transported by the transfer module23across the glass platform4so that a second side of the paper sheet251is scanned by the image processing module3.

FIG. 2(b) is a schematic perspective view illustrating a paper-feeding mechanism of the automatic document feeder inFIG. 2(a). Please refer toFIGS. 2(a) and2(b). The paper-feeding mechanism22principally includes a pick-up module221, a supporting module222and a paper stopping module223. The pick-up module221is disposed in the vicinity of the paper input tray25, and includes a pick-up roller2211and a separation roller2212. The separation roller2212is disposed in the vicinity of the pick-up roller2211and sheathed around a separation roller axle2213. The supporting module222is used for supporting the pick-up module221. Both ends of the supporting module222are also sheathed around the separation roller axle2213of the separation roller2212, so that the supporting module222is pivotal about the separation roller axle2213when the separation roller axle2213is driven by an actuating mechanism224(as shownFIG. 2(c)). Upon rotation of the supporting module222, the pick-up roller2211and the separation roller2212are either ascended or descended. When the pick-up roller2211is descended to contact with the paper sheet251, the paper sheet251is fed by the pick-up roller2211. The separation roller2212is rotated to separate the uppermost paper sheet251from the stack of paper sheets, thereby picking a single paper sheet to the transfer module23.

The supporting module222has two sustaining parts2222on bilateral sides2221thereof, respectively. An exemplary sustaining part222is a protrusion, which may be integrally formed on the sidewall2221of the supporting module222. As the supporting module222is rotated, the sustaining part2222is rotated.

The paper stopping module223is disposed beside the sidewall2221of the supporting module222and between the pick-up roller2211and the separation roller2212. When the pick-up roller2211of the pick-up module221is lifted to a standby position as shown inFIGS. 2(a) and2(b), the paper stopping module223is sustained against the front edges of the stack of paper sheets251on the paper input tray25such that the paper sheets251are hindered from being transported into the paper feeding port. Whereas, when the pick-up roller2211of the pick-up module221is lowered to the paper-feeding position as shown inFIG. 2(e), the uppermost paper sheet may be transported into the paper feeding port without being stopped by the paper stopping module223. Please refer toFIG. 2(b) again. The paper stopping module223includes two transmission members2231and two stopping plates2232. In this embodiment, the transmission member2231has an L-shaped cross-section. The short side of the L-shaped transmission member2231has a contact part2233to be contacted with the sustaining part2222of the supporting module222. The long side of the L-shaped transmission member2231has a clamp part2234for clamping the upper edge of the stopping plate2232. Since the upper edge of the stopping plate2232is clamped by the clamp part2234, the stopping plate2232is vertically uplifted or lowered. In addition, a pivotal shaft2235is disposed at the right-angle corner of the L-shaped transmission member2231, i.e. the connection region of the clamp part2234and the contact part2233. The transmission member2231is pivotal about the pivotal shaft2235.

In accordance with a feature of the present invention, a grasp arm211is protruded from an inner surface of the casing21for grasping both terminals of the pivotal shaft2235, as can be seen inFIGS. 2(a) and2(e). As a result, the paper stopping module223is disposed beside the sidewalls2221of the supporting module222and the contact parts2233of the transmission members2231are arranged beside corresponding sustaining parts2222of the supporting module22.

Please refer toFIGS. 2(a) and2(b) again. In a case that no paper-feeding instruction is received by the control circuit inside the automatic document feeder20, the pick-up roller2211is raised to a standby position without contact with the paper sheets251. Meanwhile, the contact part2233of the transmission member2231is not suppressed by the sustaining part2222of the supporting module22. Due to the weight of the paper stopping module223, the stopping plate2232is lowered to a paper-stopping position where the stopping plate2232is sustained against the front edges of the stack of paper sheets251. Under this circumstance, the paper sheets are hindered from being transported into the paper feeding port.

Please refer toFIGS. 2(d),2(e) and2(f). In a case that a paper-feeding instruction is received by the control circuit inside the automatic document feeder20, the supporting module222and the pick-up roller2211are driven by the actuating mechanism224to rotate downwardly to the lowermost position. Upon downward rotation of the supporting module222, the sustaining part2222is rotated downwardly to push forward the contact part2233of the L-shaped transmission member2231. Since the transmission member2231is pivotal about the pivotal shaft2235, the stopping plate2232is uplifted vertically. Until the pick-up roller2211contacts with the uppermost paper sheet251, the stopping plate2232is fixed at the paper-feeding position. Meanwhile, the uppermost paper sheet251may be transported into the paper feeding port without being stopped by the stopping plate2232.

When a sensor (not shown) of the automatic document feeder20detects that any paper sheet251has been fed into the paper feeding port, the supporting module222and the pick-up roller2211are driven by the actuating mechanism224to rotate upwardly to the initial position as shown inFIG. 2(a). Meanwhile, the contact part2233of the transmission member2231is not suppressed by the sustaining part2222of the supporting module22. Due to the weight of the paper stopping module223, the stopping plate2232is lowered to a paper-stopping position where the stopping plate2232is sustained against the front edges of the stack of paper sheets251. Under this circumstance, the paper sheets are hindered from being transported into the paper feeding port. Until the paper sheet251is ejected to the paper ejecting tray26, the above procedures are repeated to successively feed the remainder paper sheets one by one.

For a purpose of performing a duplex scanning operation, after the first side of the paper sheet251has been scanned and a majority of the paper sheet251is ejected to the paper ejecting tray26, the paper sheet251is turned over by the inverting member231and then transported into the passageway. Next, the paper sheet251is transported by the transfer module23across the glass platform4so that a second side of the paper sheet251is scanned by the image processing module3. Since the paper sheet251comes from the paper ejecting tray26rather than the paper input tray25at the moment when the paper sheet251is turned over by the inverting member231and transported into the passageway, the supporting module222and the pick-up roller2211may be kept at the initial position as shown inFIGS. 2(a) and2(b). Under this circumstance, the remainder paper sheets251are hindered from being transported into the paper feeding port.

From the above embodiment, for performing the duplex scanning operation by using the automatic document feeder of the present invention, the redundant procedure of rotating the stopping plate when the paper sheet is turned over and fed into the passageway may be dispensed with. As a consequence, the remainder paper sheets are precisely positioned on the paper input tray so as to enhance the performance of stopping the paper sheets. Moreover, since the stopping plate of the paper stopping module is moved to the paper-feeding position or the paper-stopping position upon downward or upward rotation of the supporting module and the pick-up module, no addition motor is required to drive the pivotal shaft of the paper stopping module. Therefore, the fabricating cost of the automatic document feeder is reduced and the operating burden is also reduced.