Paper pickup mechanism

A paper pickup mechanism for automatically picking up a paper is provided. The paper pickup mechanism includes a system motor for proceeding a first-direction rotation, and a second-direction rotation, a mounting shaft switching between a starting position and a pickup position, a first device driven by the system motor, and a second device driven by the first drive device, wherein the mounting shaft is driven by the first device to be switched from the starting position to the pickup position till the mounting shaft is limited by the paper while the system motor proceeds the first-direction rotation and the second device suffers an external force having a value less than a threshold, while the value of the external force suffered by the second device is larger than the threshold, so that the second drive device is started to move the paper, and while the system motor proceeds the second-direction rotation and the second device suffers the external force having the value less than the threshold, the mounting shaft is driven by the first device to be restored from the pickup position to the starting position.

FIELD OF THE INVENTION

This invention relates to a paper pickup mechanism, and more particularly to a paper pickup mechanism with a mounting shaft for automatically picking up a slight paper.

BACKGROUND OF THE INVENTION

An automatic paper pickup mechanism is a very important portion of many official machines, such as printers, facsimile machines, and copying machines. The automatic paper pickup mechanism can automatically feed a stack of paper once a page into the official machine for proceeding follow-up actions, for example, printing, faxing, and copying. And, a paper pickup mechanism with a mounting shaft is a general one. In the conventional technologies, for example, an ACM (Auto Compensation Mechanism) of U.S. Pat. No. 5,527,026, the mounting shaft for picking up the paper is located at the pick-up position so as to contact with the paper, but, under this condition, if the paper is soft and slight and has less rigidity, the mounting shaft will not be urged by the paper to locate at a correct position which will always get the paper stuck. In addition, for solving the paper stuck problem described above, some other prior arts utilize a system motor to provide the power for feeding paper and additionally employ an expensive electromagnetic valve or another reserved motor for driving the mounting shaft. However, these structures cause the paper mechanism more complicated and also cost more.

It is clear that because the mounting shaft of the conventional paper pickup mechanism can not automatically move up and down, it will cause the soft and slight paper to get stuck and further bother the user. Simultaneously, if the structure of the paper pickup mechanism for moving the mounting shaft automatically becomes more complicated and the manufacturing cost increases, the competitiveness of the product will be seriously influenced. Consequently, how to move the mounting shaft automatically under a simplest mechanism for solving the paper stuck problem and reducing the cost becomes the main purpose of the present invention.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a paper pickup mechanism which can be automatically moved up and down only by employing the obverse and reverse rotation of one system motor.

It is another object of the present invention to provide a paper pickup mechanism which can prevent the soft and slight paper to get stuck by means of the reacting force produced by rubbing against the feeding paper for supplementing the friction so as to guarantee the success of the paper pickup.

According to an aspect of the present invention, a paper pickup mechanism for automatically picking up a paper includes a system motor for proceeding a first-direction rotation, and a second-direction rotation, a mounting shaft switching between a starting position and a pickup position, a first device driven by the system motor, and a second device driven by the first drive device, wherein the mounting shaft is driven by the first device to be switched from the starting position to the pickup position till the mounting shaft is limited by the paper while the system motor proceeds the first-direction rotation and the second device suffers an external force having a value less than a threshold, while the value of the external force suffered by the second device is larger than the threshold, so that the second drive device is started to move the paper, and while the system motor proceeds the second-direction rotation and the second device suffers the external force having the value less than the threshold, the mounting shaft is driven by the first device to be restored from the pickup position to the starting position.

Preferably, the first device includes a first gear driven by the system motor, a transmission shaft jointed with the first gear, and a second gear sleeving around the transmission shaft for driving the second device.

Preferably, the mounting shaft is pivoted on the transmission shaft when the second device suffered the external force having the value less than the threshold.

Preferably, the second device includes a connecting shaft, a third gear jointed on the connecting shaft and engaged with the second gear of the first device, and a torque limiting module on the connecting shaft for limiting the third gear to rotate around the connecting shaft when the third gear suffers the external force having the value larger than the threshold.

Preferably, the second device further includes a pickup roller for sleeving around the connecting shaft and connecting with the third gear, wherein the mounting shaft is driven along with the first-direction rotation proceeded by the system motor to rotate around the transmission shaft so as to switch from the starting position to the pickup position for contacting the pickup roller with a top of the paper while the system motor proceeds the first-direction rotation and the second device suffers the external force having the value less than the threshold, when the pickup roller urging against the paper produces a reacting force causing the external force having the value larger than the threshold, the pickup roller starts rotating to displace the paper, and then when the system motor proceeds the second-direction rotation and the second device suffers the external force having the value less than the threshold, the mounting shaft is driven along with the second-direction rotation proceeded by the system motor to counter rotate around the transmission shaft so as to be switched from the pickup position to the starting position for providing a distance between the pickup roller and the paper.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1shows the structural view of the paper pickup mechanism in the preferred embodiment according to the present invention. As shown inFIG. 1, the paper pickup mechanism includes a system motor (not shown) and a mounting shaft10. The system motor can proceed a first-direction rotation and a second-direction rotation. The mounting shaft10includes a first device and a second device, wherein the first device includes a first gear1011, a transmission shaft1012, and a second gear1013, and the second device includes a connecting shaft1021, a third gear1022, a torque limiting module1023, and a pickup roller1024.

In the first device, the first gear1011is driven by the system motor so as to drive the transmission shaft1012which is jointed therewith, and the second gear1013sleeves around the transmission shaft1012for driving the third gear1022of the second device. Furthermore, the mounting shaft10is consisted by an upper cover103and a base104, and the transmission shaft1012sleeves around the upper cover103and the base104.

Regarding to the second device, the connecting shaft1021of the second device is fixedly connected to the upper cover103and the base104, and the third gear1022sleeves around the connecting shaft1021and engages with the second gear1013of the first device. Moreover, the torque limiting module1023which is set on the connecting shaft1021can provide a torque to the third gear1022for resisting a rotation caused by the connecting shaft1021. However, when the third gear1022suffers an external force having a value larger than a threshold, it will then be rotated by the connecting shaft1021. And, the pickup roller1024also sleeves around the connecting shaft1021and engages with the third gear1022.

Please further refer to FIGS.2(A)˜2(F) illustrating the schematic views of the continuous motions in the preferred embodiment according to the present invention. In FIG.2(A), it shows the starting position of the mounting shaft10. At the beginning, the system motor starts to proceed a first-direction rotation which will also drive the transmission shaft1012and the second gear1013to rotate. However, if the external force suffered by the third gear1022has a value less than the threshold because of the limiting by the torque limiting module1023, the system motor will fail to drive the engaged second gear1013and third gear1022. Thus, the power produced by the system motor will then drive the whole mounting shaft10to rotate down through the transmission shaft1012, the mounting shaft10will gradually switch from the starting position to the pickup position, and it results the pickup roller1024to be contacted with the paper (as shown in FIG.2(B)). Continuously, a reacting force will be suffered by the pickup roller1024because the pickup roller1024is contacted with the paper. The reacting force causes the external force suffered by the second device to have a value larger than the threshold which results in the third gear1022to overcome the torque limiting module1023and proceed a rotation caused by the transmission shaft1012. Accordingly, the pickup roller1024will be driven to rotate so as to start feeding the paper (as shown in FIG.2(C)).

Please then refer to FIG.2(D). The paper is moved to a deliver roller105by the pickup roller1024for being transmitted continuously. Until the paper is driven by another roller downstream (not shown), the system motor will be changed to proceed the counter directional second-direction rotation which will simultaneously drive the transmission shaft1012and the second gear1013. At this time, also because of the torque limiting module1023, the third gear1022which is engaged with the second gear1013will again suffer the external force having a value less than the threshold, so that it will not overcome the limitation to rotate. Identically, the power of the system motor will drive the whole mounting shaft10to rotate up through the transmission shaft1012(as shown in FIG.2(E)), the mounting shaft10will gradually switch from the pickup position to the starting position (reject to the boundary20), and it results the pickup roller1024to be displaced the paper (as shown in FIG.2(F)). At this point, a reacting force produced by the contact with the boundary20will still cause the external force suffered by the third gear1022to have a value larger than the threshold which results the third gear1022to overcome the torque limiting module1023, proceed a counter rotation and drive the pickup roller1024to rotate. However, this will not cause any influence because the pickup roller is a distance away the paper.

According to the preferred embodiment described above, the structure of the present invention utilizes the single motor system and the torque limiting module to drive the mounting shaft to automatically move up and down without contacting with the paper at the beginning. Therefore, even when the paper is soft and slight, the situation that the mounting shaft can not be switched to a correct position because of the insufficient rigidity of the paper will not be happened again. Simultaneously, the mounting shaft of the present invention also can save the expansive electromagnetic valve or another motor for driving the mounting shaft in the prior arts. Furthermore, the number of the gears in the paper pickup mechanism is fewer, too. Consequently, the main purposes of the present invention for solving the defects of complicated structure and high manufacturing cost are achieved.

In view of the aforesaid, the paper pickup mechanism of the present invention eliminates the paper stuck problem which is caused by the insufficient rigidity of the soft and slight paper during transmission. Furthermore, compared with the prior arts, the paper pickup mechanism is an uncomplicated structure. Thus, this is a paper pickup mechanism which can solve the permanent paper stuck problem. In addition, the technology of the present invention can also be utilized by the important tools of the products in different fields, such as printers, fax machines, and copying machines. Consequently, the present invention is a significant improvement and development.