Sheet pick-up device of automatic document feeder

A sheet pick-up device of an automatic document feeder is provided. The sheet pick-up device includes a two-way clutch transmission mechanism, a sheet pick-up arm, a stopper and a linking assembly. When the two-way clutch transmission mechanism is operated to have the sheet pick-up arm move to a standby position, the stopper is moved with the linking assembly to be in a stopping position. Whereas, when the two-way clutch transmission mechanism is operated to have the sheet pick-up arm move to a sheet pick-up position, the stopper is in a non-stopping position. The sheet pick-up device has enhanced operating stability.

FIELD OF THE INVENTION

The present invention relates to a sheet pick-up device, and more particularly to a sheet pick-up device of an automatic document feeder.

BACKGROUND OF THE INVENTION

Generally, an automatic document feeder has a function of automatically and successively feeding many paper sheets. The automatic document feeder is applied to a diversity of office machines such as multifunction peripherals, printers, faxing machines or scanners.

FIG. 1Ais a schematic perspective view illustrating a conventional automatic document feeder. The automatic document feeder1as shown inFIG. 1Ais applied to a printer. The automatic document feeder1comprises a sheet stopping mechanism11, a sheet pick-up roller12, a clutch gear13, a belt14, a motor15, a big gear16, an idle gear17, a compound gear18. The sheet pick-up roller12is used for transporting a paper sheet M into a sheet-feeding channel. The clutch gear13is used for driving rotation of the sheet pick-up roller12. The belt14is driven to rotate by the motor15. Upon rotation of the belt14, the big gear16is rotated to simultaneously drive rotation of the clutch gear13and the idle gear17. The compound gear18is rotated with the idle gear17.

FIG. 1Bis a schematic exploded view illustrating the sheet stopping mechanism of the automatic document feeder as shown inFIG. 1A.FIG. 1Cis a schematic side view illustrating the automatic document feeder in a sheet-feeding status. The sheet stopping mechanism11comprises a swinging arm110, a hollow ring111, a coupling element112and a linking rod113. In addition, plural elastic elements111aare formed on the outer periphery of the hollow ring111. The coupling element112is coupled with the hollow ring111. The linking rod113is connected to the swinging arm110and a stopper114. The swinging arm110, the hollow ring111and the coupling element112are sheathed around an outer surface181of the compound gear18. In a sheet pick-up status, the sheet pick-up roller12is rotated to transport the paper sheet M in a direction F (seeFIG. 1C). Meanwhile, as the compound gear18is rotated, the elastic element111aand a corresponding coupling element112are rubbed against each other to generate a friction force. Due to the friction force, the swinging arm110is swung, and thus the stopper114is switched to the non-stopping position without stopping the paper sheet M. In this situation, the paper sheet M is allowed to be fed into the sheet-feeding channel.

The conventional automatic document feeder1, however, still has some drawbacks. For example, since the swinging arm110of the automatic document feeder1is swung in response to the friction force, which is generated from the nib between the elastic element111aand the corresponding coupling element112. In such way, the elastic element111amay be suffered from thermal deformation. Due to the rubbing problem for a long time, the elastic element111ais eventually abraded, and thus the long-term operating stability is deteriorated. In this situation, the use life of the automatic document feeder is shortened.

SUMMARY OF THE INVENTION

The present invention provides a sheet pick-up device of an automatic document feeder in order to enhance the operating stability.

In accordance with an aspect of the present invention, there is provided a sheet pick-up device of an automatic document feeder. The sheet pick-up device has functions of stopping a paper sheet from entering a sheet-feeding channel and feeding the paper sheet into the sheet-feeding channel. The sheet pick-up device includes a two-way clutch transmission mechanism, a sheet pick-up arm, a stopper and a linking assembly. The two-way clutch transmission mechanism includes a power input shaft and a clutch gear set coaxial with the power input shaft. The power input shaft is driven to rotate in either a clockwise direction or an anti-clockwise direction by a motor. The sheet pick-up arm is fixedly connected to the power input shaft and configured for transporting the paper sheet into the sheet-feeding channel. The stopper perpendicular to a stopper linking rod is used for stopping the paper sheet from entering the sheet-feeding channel. The linking assembly is connected to the power input shaft and the stopper. When the power input shaft is rotated in the clockwise direction, the sheet pick-up arm is in a standby position, and the stopper is moved with the linking assembly to be in a stopping position, so that the paper sheet is stopped from entering the sheet-feeding channel. Whereas, when the power input shaft is rotated in the anti-clockwise direction, the sheet pick-up arm is in a sheet pick-up position, and the stopper is moved with the linking assembly to be in a non-stopping position, so that the paper sheet is allowed to be fed into the sheet-feeding channel.

In an embodiment, the clutch gear set includes a position-changing plate, a driving gear, a first switching gear, a second switching gear and a notched gear. The position-changing plate is sheathed around the power input shaft and fixed on the power input shaft. The driving gear is disposed on the position-changing plate and sheathed around the power input shaft. The first switching gear is disposed on the position-changing plate. The second switching gear is disposed on the position-changing plate and engaged with the driving gear. The notched gear is disposed on a rotary shaft, and having a notch in a periphery thereof. When the power input shaft is rotated in the clockwise direction, the position-changing plate is rotated, so that the first switching gear is engaged with notched gear, the notched gear is rotated with the first switching gear, and the stopper is moved with the linking assembly to be in the stopping position. Until the notch of the notched gear is rotated to be aligned with the first switching gear, the first switching gear runs idle. When the power input shaft is rotated in the anti-clockwise direction, the position-changing plate is rotated, so that the second switching gear is engaged with notched gear, the notched gear is rotated with the second switching gear, and the stopper is moved with the linking assembly to be in the non-stopping position. Until the notch of the notched gear is rotated to be aligned with the second switching gear, the second switching gear runs idle.

In an embodiment, the clutch gear set further includes a transmission gear, which is disposed on the position-changing plate, and engaged with the driving gear and the first switching gear.

In an embodiment, the stopper is perpendicularly disposed on a stopper linking rod. The linking assembly includes a cam, a swinging arm and a repositioning structure. The cam is disposed on the rotary shaft. The swinging arm is disposed on the power input shaft, and swung in response to a rotary motion of the cam. The repositioning structure comprises a rotating rod, a poking part, a torsion spring, a first linking element and a second linking element. The poking part is perpendicular to the rotating rod and contacted with the swinging arm. The torsion spring is sheathed around the rotating rod, and contacted with the poking part for exerting a torsion force on the poking part. The first linking element is connected to an end of the rotating rod. The second linking element is perpendicular to the stopper linking rod and contacted with the first linking element.

In an embodiment, the rotary shaft is parallel with the power input shaft.

In an embodiment, the notched gear, the rotary shaft and the cam are integrally formed.

In an embodiment, the first linking element includes a hollow part and a position-limiting structure, and the second linking element is penetrated through the hollow part, and contacted with the position-limiting structure of the first linking element.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention provides a sheet pick-up device of an automatic document feeder of an office machine such as a printer. The automatic document feeder is suitable for picking up paper sheets from the bottom side.

FIG. 2is a schematic perspective view illustrating a sheet pick-up device of an automatic document feeder according to an embodiment of the present invention. As shown inFIG. 2, the sheet pick-up device2comprises a two-way clutch transmission mechanism23, a sheet pick-up arm22, plural stoppers21and a linking assembly24. The two-way clutch transmission mechanism23comprises a power input shaft231and a clutch gear set232. When the power input shaft231is driven by a motor (not shown), the power input shaft231is rotated in either a clockwise direction D or an anti-clockwise direction S, and thus the paper sheet M supported on the sheet input tray3may be smoothly fed into the sheet-feeding channel by the sheet pick-up device2. Moreover, as shown inFIG. 2, the sheet pick-up device2further comprises a stopper linking rod210, which is perpendicular to the stoppers21.

FIG. 3is a schematic exploded view illustrating the sheet pick-up device as shown inFIG. 2. The clutch gear set232comprises a position-changing plate2320, a driving gear2321, a first switching gear2322, a second switching gear2323, a transmission gear2324and a notched gear2325. The notched gear2325has a notch23251in a periphery thereof. The notched gear2325is disposed on a rotary shaft25. The driving gear2321, the first switching gear2322, the second switching gear2323and the transmission gear2324are disposed on the position-changing plate2320. The transmission gear2324is engaged with the driving gear2321and the first switching gear2322. The linking assembly24comprises a cam240, a swinging arm241and a repositioning structure242. Both of the cam240and the notched gear2325are disposed on the same rotary shaft25. The swinging arm241is disposed on the power input shaft231, and swung in response to a rotary motion of the cam240. The repositioning structure242comprises a rotating rod2420, a poking part2421, a torsion spring243, a first linking element2422and a second linking element2423. The poking part2421is perpendicular to the rotating rod2420, and contacted with the swinging arm241. The torsion spring243is sheathed around the rotating rod2420and contacted with the poking part2421for exerting a torsion force on the poking part2421. The first linking element2422is connected to an end of the rotating rod2420. The second linking element2423is perpendicular to the stopper linking rod210.

FIG. 4is a schematic assembled view illustrating the sheet pick-up device as shown inFIG. 3, in which the sheet pick-up device is in a standby status. The first linking element2422comprises a hollow part2422aand a position-limiting structure2422b. The second linking element2423is penetrated through the hollow part2422a, and contacted with the position-limiting structure2422bof the first linking element2422.

FIG. 5Ais a schematic side view illustrating the sheet pick-up device of the present invention, in which the sheet pick-up device is in a standby status. Please refer toFIGS. 4 and 5A. When the power input shaft231is driven by the motor to rotate in the clockwise direction D, the sheet pick-up arm22is moved with the power input shaft231to be in a standby position. As the power input shaft231is rotated, the position-changing plate2320is rotated, so that the first switching gear2322is engaged with the notched gear2325and the notched gear2325is rotated with the position-changing plate2320. Since the notched gear2325is rotated with the cam240, the swinging arm241is swung to push the poking part2421upwardly. In such manner, the first linking element2422is nearly upright. As the second linking element2423is moved with the first linking element2422, the second linking element2423is contacted with the position-limiting structure2422b, and the stopper21is moved to a stopping position. When the stopper21is in the stopping position, the first paper sheet M1of the paper sheets M is stopped from entering the sheet-feeding channel. Until the notch23251of the notched gear2325is rotated to be aligned with the first switching gear2322, the first switching gear2322runs idle.

FIG. 5Bis a schematic side view illustrating the sheet pick-up device of the present invention, in which the sheet pick-up device is in a sheet pick-up status.FIG. 6is a schematic assembled view illustrating the sheet pick-up device of the present invention, in which the sheet pick-up device is in a sheet pick-up status. Please refer toFIGS. 5B and 6. When the power input shaft231is driven by the motor to rotate in the anti-clockwise direction S, the sheet pick-up arm22is moved with the power input shaft231to be in a sheet pick-up position. As the power input shaft231is rotated, the position-changing plate2320is rotated, so that the second switching gear2323is engaged with the notched gear2325and the notched gear2325is rotated with the position-changing plate2320. Since the notched gear2325is rotated with the cam240, the poking part2421is no longer pushed upwardly by the swinging arm241. In such manner, the first linking element2422and the second linking element2423are tilted. As such, the stopper21is moved to a non-stopping position. When the stopper21is in the non-stopping position, the first paper sheet M1of the paper sheets M is allowed to be fed into the sheet-feeding channel. Until the notch23251of the notched gear2325is rotated to be aligned with the second switching gear2323, the second switching gear2323runs idle.

From the above description, the sheet pick-up device of the present invention uses the two-way clutch transmission mechanism23to change the action of the linking assembly24. Since the action of the linking assembly24is changed, the sheet pick-up arm22and the stopper21are moved in opposite directions to achieve the purpose of either stopping a paper sheet from entering a sheet-feeding channel of the automatic document feeder or feeding the paper sheet into the sheet-feeding channel.

As previously described in the prior art, by rubbing the elastic element111aand a corresponding coupling element112against each other to generate a friction force, the swinging arm110is swung, and thus the function of either stopping the paper sheet or allowing the paper sheet to be fed into the sheet-feeding channel is implemented. According to the prior art technology, the elastic element111aand the coupling element112may be suffered from thermal deformation. The rubbing problem may eventually abrade the elastic element111a, and deteriorate the long-term operating stability. Whereas, according to the present invention, the sheet pick-up arm22, the swinging arm241and the driving gear2321are disposed on the same power input shaft231. As a consequence, when the power input shaft231is rotated, the sheet pick-up arm22, the swinging arm241and the driving gear2321are synchronously operated. In this situation, the operation time between components is reduced, and the operating stability of the sheet pick-up device of the present invention will be enhanced.