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Automatic sheet feeder having a flexible element on one end of the pick shaft

1. Field of the Invention

the present invention relates to an automatic sheet feeder, and more specifically, to an automatic sheet feeder having a flexible element on one end of the pick shaft.

2. Description of the Prior Art

Most image processing machines such as copiers, fax machines, printers, scanners, or multifunctional business machines are equipped with an auto sheet feeder (ASF) for feeding recording medium into the main section of the image processing machines. To lower the cost for manufacturing, the driving power generated by a motor for driving the ASF is also utilized to drive the paper conveying device. In the image processing machines the power is transmitted to each operating part through the gear set therein. A prior art ASF can handle one-way paper feeding as the motor drives the gear sets, which then drives a ratchet to rotate, and finally the ratchet, which connects with the pick shaft of the ASF, drives the pick shaft to rotate in one-way direction.

Since the ASF allows the papers to proceed in one direction and when the image processing machine does not feed the papers, the ASF (also known as the driven member) shall not be driven by the driving member (the ratchet and the gear set), the prior art ASF has an O-ring of particular appearance and a clutch member installed on one end of the pick shaft. Please refer to FIG. 1 and FIG. 2. The automatic sheet feeder disclosed in the U.S. Pat. No. 6,899,326 in FIG. 1 and FIG. 2 has an O-ring 140 on the pick shaft 110 for operating with the ratchet 120. The O-ring 140 comprises a pawl 144 and a brake pin 142. The pawl 144 is engaged with the ratchet 120 so that when the ratchet 120 rotates along the direction CW, the ratchet 120 can drive the pick shaft 110 to rotate along the direction CW as well, which is shown in FIG. 1. When the image processing machine does not feed the papers, a clutch in the image processing machine pushes the brake pin 142 in the direction F, making the O-ring 140 to rotate along the direction CCW taking the shaft 146 as the axle, which is shown in FIG. 2. At this time, the pawl 144 disengages with the ratchet 120, the ratchet 120 has an idle running with the pick shaft 110, and the restoring spring 150 connected between the pick shaft 110 and the O-ring 140 is elongated and has a restoring force. When the image processing machine is in the paper feeding procedure again, the clutch stops pushing the brake pin 142 and the restoring force of the restoring spring 150 pulls the O-ring 140 along the direction CW, making the pawl 144 of the O-ring 140 to engage with the ratchet 120 so as to drive the pick shaft 110 to rotate.

However, in the ASF according to the prior art, the aforementioned one-way driving and disengagement are accomplished by the O-ring 140 and the restoring spring 150, the assembly of which is complicated as well: the restoring spring 150 must be installed with one end on the hook of the pick shaft 110 and a rotating axle 146 of the O-ring 140 installed on a rotating pivot of the pick shaft 110. Then a pair of tweezers is necessary for clipping the other end of the restoring spring 150, stretching the restoring spring 150, hooking the other end of the restoring spring 150 on the hook of the O-ring 140. As the O-ring 140 and the restoring spring 150 are kept in the position, the ratchet 120 is assembled then. The process of assembly according to the prior art is very complicated and the assembled elements are very easy to fall apart. Furthermore, the O-ring 140 and the restoring spring 150 raise the cost as well.

The claimed invention provides an automatic sheet feeder having a flexible element on one end of the pick shaft. The automatic sheet feeder comprises a ratchet having a plurality of teeth and a pick shaft having a flexible element. The flexible element comprises a fixed section extending from the end of the pick shaft and a fluctuation section extending from the fixed section capable of moving close to or away from an axis. The fluctuation section comprises at least a pawl for engaging with the teeth of the ratchet, allowing the ratchet for rotating the pick shaft.

The claimed invention also provides an automatic sheet feeder having a flexible element on one end of the pick shaft. The automatic sheet feeder comprises a ratchet having a plurality of teeth and a pick shaft having a flexible element extending from the end of the pick shaft. The flexible element is capable of moving close to or away from an axis and comprises at least a pawl for engaging with the teeth of the ratchet, allowing the ratchet for rotating the pick shaft.

These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.

FIG. 1 and FIG. 2 are illustrations of the O-ring operating with the ratchet in the automatic sheet feeder according to the prior art.

FIG. 3 is an illustration of the automatic sheet feeder according to the present invention.

FIG. 4 is an illustration of the flexible element on one end of the pick shaft.

FIG. 5 is an illustration of the cross section of the flexible element in FIG. 4.