Energy storing sheet feeder

Abstract

A sheet feeder includes a separation roller, a friction roller, a shaft and an energy storing element. The energy storing element stores energy when the friction roller is driven by the separation roller to rotate in the sheet-feeding direction and releases energy to make the friction roller rotate in a direction opposite to the sheet-feeding direction.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:

FIGS. 1 to 3 are schematic illustrations showing operations of a conventional sheet feeder.

FIGS. 4 to 7 are schematic illustrations showing operations of a sheet feeder according to a preferred embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be apparent from the following detailed description, which proceeds with reference to the accompanying drawings, wherein the same references relate to the same elements.

FIGS. 4 to 7 are schematic illustrations showing operations of a sheet feeder according to a preferred embodiment of the invention. As shown in FIGS. 4 to 7, the energy storing sheet feeder according to this embodiment feeds and separates a first sheet S1 and a second sheet S2, which are stacked together. The energy storing sheet feeder includes a separation roller 10, a friction roller 20, a shaft 30 and an energy storing element 40. The separation roller 10 is driven by a rotating shaft 14 of a driving device 12 to rotate. The friction roller 20 may be rotated by the separation roller 10 as well as the first sheet S1 or the second sheet S2. The shaft 30 passes through the friction roller 20. The shaft 30 moves relative to the rotating friction roller 20 and the energy storing element 40 is disposed between the shaft 30 and the friction roller 20. Alternatively, the shaft 30 may be stationary relative to the rotating friction roller 20 and the energy storing element 40 is connected to the shaft 30. The energy storing element 40 may be a worm spring or a torsional spring. The energy storing element 40 stores energy when the friction roller 20 is driven by the separation roller 10 to rotate in the sheet-feeding direction and releases energy to make the friction roller 10 rotate in a direction opposite to the sheet-feeding direction.

In order to make the energy storing element 40 store some energy during the initial setting process, the energy storing element 40 may be preloaded to store the predetermined energy. It is to be noted that when the energy storing element 40 has stored the maximum energy, no more energy can be stored in the energy storing element 40. However, the action of the energy storing element 40 would not impede the rotation of the friction roller 20 when a mechanism, such as a one-way clutch, is used.

The friction roller 20 has a first forwarding state, a reversing state and a second forwarding state. In the first forwarding state, as shown in FIG. 4, the separation roller 10 rotating clockwise drives the friction roller 20 to rotate counterclockwise to feed the first sheet S1 or the first sheet S1 and the second sheet S2. At this time, the friction roller 20 also drives the energy storing element 40 to make the energy storing element 40 store the energy.

In the reversing state, that is, when the sheets S1 and S2 simultaneously enter a nip 60 between the friction roller 20 and the separation roller 10, as shown in FIG. 5, the energy storing element 40 releases the energy to reverse the friction roller 20 clockwise because the friction between the sheets S1 and S2 is smaller than the friction between the sheet S2 and the friction roller 20. Thus, the second sheet S2 can be pushed out of the nip 60 between the friction roller 20 and the separation roller 10, and the state shown in FIG. 6 may be obtained. When the sheet is being transported, the state may also be changed from that of FIG. 6 to that of FIG. 5. Thus, the friction roller 20 may rotate clockwise or counterclockwise intermittently to keep only one sheet in the nip 60. In other words, the energy storing element releases the energy to reverse the friction roller to push one of the sheets out of the nip as long as two sheets enter the passageway.

In the second forwarding state, as shown in FIGS. 6 and 7, the separation roller 10 drives the second/first sheet S2/S1 to make the second/first sheet S2/S1 rotate the friction roller 20 to make the energy storing element 40 store the energy.

In addition, the energy storing sheet feeder may further include a spring or a force-applying mechanism 50 of a hydraulic device, which pushes the separation roller 10 against the friction roller 20. Alternatively, the weight of the separation roller 10 may be utilized to push the separation roller 10 against the friction roller 20. Such a design makes the feeder be adapted to the sheets with various thicknesses and immediately compensates for the worn separation roller or the worn friction roller.

According to the sheet feeder of the invention, no torque limiter has to be utilized, and the energy storing element is utilized to achieve the advantage of reducing the cost and the size effectively. Because only one single power source is used, the feeder can be assembled in a simpler manner. Because rolling friction states are created between the friction roller and the separation roller and between the friction roller and the sheet, the wear of the friction roller can be effectively reduced, and the lifetime of the friction roller may be thus lengthened.

While the invention has been described by way of example and in terms of a preferred embodiment, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications. Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications.

Claims

1. An energy storing sheet feeder for feeding and separating a first sheet and a second sheet, which are stacked together, the sheet feeder comprising: a separation roller rotating in a sheet-feeding direction and driven by a driving device;a friction roller, which may be rotated by the separation roller;a shaft, which passes through the friction roller; andan energy storing element for storing energy when the friction roller is driven by the separation roller to rotate in the sheet-feeding direction and for releasing energy to make the friction roller rotate in a direction opposite to the sheet-feeding direction.

2. The sheet feeder according to claim 1, wherein the friction roller has a first forwarding state, a reversing state and a second forwarding state, wherein: in the first forwarding state, the separation roller rotates the friction roller to feed the first sheet alone or to feed the first sheet and the second sheet simultaneously, and the friction roller drives the energy storing element to make the energy storing element store the energy;in the reversing state, the energy storing element releases the energy to reverse the friction roller to push the second sheet away from a nip between the friction roller and the separation roller; andin the second forwarding state, the separation roller drives the second/first sheet to make the second/first sheet rotate the friction roller and thus make the energy storing element store the energy.

3. The sheet feeder according to claim 1, wherein the shaft moves relative to the rotating friction roller and the energy storing element is disposed between the shaft and the friction roller.

4. The sheet feeder according to claim 1, wherein the shaft is stationary relative to the rotating friction roller and the energy storing element is connected to the shaft.

5. The sheet feeder according to claim 1, wherein the energy storing element is a worm spring or a torsional spring.

6. The sheet feeder according to claim 5, wherein the energy storing element is preloaded to store predetermined energy in advance.

7. The sheet feeder according to claim 1, further comprising: a force-applying mechanism for pushing the separation roller against the friction roller.

8. The sheet feeder according to claim 7, wherein the energy storing element is a worm spring or a torsional spring.

9. The sheet feeder according to claim 8, wherein the energy storing element is preloaded to store predetermined energy in advance.