CN1098166C - Auto sheet feeder for use in printing apparatus - Google Patents

Abstract

An automatic paper feeding mechanism, wherein the locking gear and the feeding roller driving gear are integrated and installed coaxially with the third idler wheel. The locking gear and the feed roller drive gear have a groove to fit and hold the elastic ring with two flanges. The hem of the elastic ring is in selective contact with the protrusion on the tab. Depending on the direction of rotation of the gears in the gear train, the power transmission from the motor to the feed roller can be intermittent by means of pin action, thus controlling the feed of the print run.

Description

Automatic paper feeder for printing equipment

This application refers to and includes Utility Model Application for Automatic Paper Feed Mechanism of Printer published by the Korean Industrial Property Office on November 24, 1995, and claims all rights expressed under 35 U.S.C Section 119. The utility model application has been officially numbered NO.35419/1995 by the Korean Industrial Property Office.

This invention relates generally to automatic paper feeders, and in particular to an improved automatic paper feed mechanism for feeding one sheet at a time from a paper tray in printing equipment, such as printers, glossy paper facsimile machines, etc., to perform printing operations.

From the printer literature, especially from Figure 1, it is known that the feeding system includes a feeding roller, which is mounted on the frontmost part of the paper, and the feeding system is elastically biased against the feeding roller to press a stack of papers in the direction of spring tension. The guide plate 40 is disposed closest to the front end portion of the paper tray 10 so as to guide the paper during the printing operation. Both the conveyance roller 15 and the pinch roller 17 are installed on a paper conveyance path guided by a guide plate 40 . When paper is fed, the paper feed roller that is in contact with the uppermost piece of paper in the paper tray 10 is driven, and the uppermost paper moves to the conveying roller 15 by means of the friction force of the paper feed roller. The paper is then transported by transport rollers 15 to a position suitable for printing.

The printing apparatus as described above feeds paper at a predetermined speed and quantity, which is determined by the transmission operation of the feed rollers during printing.

Therefore, the printing apparatus as described above cannot simultaneously drive the paper feeding roller and the conveying roller to convey paper. Therefore, the above two rollers are required to rotate in opposite directions, or the sheets are forced to enter the paper feeding mechanism in the above-mentioned printing device. The generally widely used mechanism is shown in FIG. 2 .

In this mechanism, the intermediate gear 72 meshes with the first gear 71 connected to the rotation shaft of the motor 70 . The second gear 73 driving the conveying roller meshes with the intermediate gear 72 on one side. The idler gear 75 a meshes with the other side of the intermediate gear 72 . Most of the idlers are arranged in a line to transmit the power of the motor 70 to the cam 76 . An idler 75e among these power transmission idlers is connected to a cam 76 so that the pallet 30 can be moved. The other idler gear 75c meshes with the third gear 74 which drives the feed roller 90, which is operated through a one-way coupling.

In operation, when the motor starts to rotate in the clockwise direction, the first gear 71 and the intermediate wheel 72 meshed with it rotate in the opposite direction. The pallet 30 is supported by a cam 76 connected to an idler gear 75e, which is one of a number of idler gears which mesh with the intermediate gear 72 in sequence. At the same time, the third gear 74 connected by the one-way coupling conveys the uppermost sheet of paper 50 to the conveying roller 15 by rotating the mostly crescent-shaped paper feeding roller for one revolution.

Then, the motor 70 rotates in the reverse direction to drive the first gear 71 and the intermediate gear 72 , thereby driving the second gear 73 . The transport roller 15 is driven by means of the rotational movement of the second gear 73, whereby the paper is placed in a position suitable for printing.

The above-mentioned conventional configuration requires the use of a large number of idlers, thus requiring a large number of components, which complicates the assembly process and reduces the reliability of the product. In addition, a sensor 95 is required to determine the proper position of the half-moon feed roller 90 after one rotation, which ultimately complicates the control circuit for the printing operation.

Based on my research on these current samples, I think there is a need for an improved automatic paper feeding mechanism as in the present invention.

An object of the present invention is to provide an automatic paper feeder for printing equipment.

Another object of the present invention is to provide an automatic paper feeding device with simple structure and reduced size.

Still another object of the present invention is to reduce the time required for the paper feeding operation by simplifying the transmission mechanism.

To achieve the above and other objects, the present invention provides an automatic paper feeding device for printing equipment. The device as described above incorporates an electric motor for generating and transmitting power. A pair of idler gears mesh with both sides of an intermediate gear, which meshes with a gear connected to the motor shaft. One of the idler gears meshes with the other idler gear coaxially mounted with the lock gear and the feed roller drive gear. The above locking gear has a generally circular groove for mounting the elastic ring.

Another idler gear as described above has a shaft protruding from the inner side of the circumference next to its gear teeth.

The shaft is provided with a locking pin near the inner surface of the idler. A fin is also mounted opposite the shaft. The fins are perpendicular to the direction of the shaft.

There is an integral protrusion on the fin. This projection can collide with a folded edge of the above-mentioned ring, disengaging or locking the locking pin according to the direction of rotation of the gear mounted on the same shaft, thereby controlling the feed roller drive gear.

A more complete understanding of the present invention, and a better understanding of its attendant advantages, may be obtained by referring to the following detailed description in conjunction with the accompanying drawings, in which like reference numbers represent like or similar parts, wherein:

Figure 1 is a brief elevation view showing traditional printing equipment;

Fig. 2 is a brief elevation view of an existing automatic paper feeding device;

Fig. 3 is an exploded perspective view of the best embodiment of the transmission part of the automatic paper feeding device manufactured according to the principle of the present invention;

Figure 4 illustrates the operational state of the device of Figure 3, wherein the locking pin maintains the rotational movement of the locking gear; and

Figure 5 shows another operational state of the device of Figure 3 in which the locking pin is disengaged.

Referring now to FIG. 3, the motor 80 is mounted on the back of the frame 100 to drive the printing equipment. The gear 110 coaxially connected with the motor 80 meshes with the outer wheel 120 a of the duplex idler gear 120 . The inner wheel 120b of the idler wheel 120 meshes with the idler wheel 140 and the transmission wheel 130, so that the motor 80 can complete the transmission in two directions. The conveying roller drive gear 145 is installed coaxially with the idler wheel 140 .

The above-mentioned idler wheel 140 and the paper feed roller drive gear 145 are installed coaxially, so they can rotate in any direction without restriction.

The above-mentioned double conveying roller transmission gear 145 is integrally installed with the locking gear 150 and meshes with the paper feed roller gear. The locking gear 150 is selectively contactable with a locking pin 180 on the idler gear 140 .

The generally circular recess 157 between the lock pin gear 150 and the feed roller drive gear 145 houses a ring 190 having a pair of folded edges 190a and 190b which are selectively engageable by projections 185 on the tab 181 .

In operation, the motor 80 initially rotates to advance paper. As the motor 80 rotates in the normal direction, the idler pulley 120 is forced to rotate in the clockwise direction, thereby forcing the delivery roller driving wheel 130 to rotate in the counterclockwise direction. As a result, the feed roller 15 engaged with the feed roller drive wheel 30 rotates in the clockwise direction to prevent paper feeding.

The idler wheel 140 meshing with the idler wheel 120 rotates counterclockwise to drive the paper feeding roller transmission gear 145 coaxially mounted with the idler wheel 140 , and then drives the paper feeding roller 11 to feed paper from the paper tray 10 . The operation of the feed roller 11 is explained in detail below.

When the idler wheel 140 rotates, the projection 185 of the fin 181 attached to the shaft 142 collides with the flange 190a of the ring 190, thereby interlocking the stop pin 180 rotating along the shaft 142 with the stop pin gear 150. As a result, the lock pin gear 150 meshes with the idler gear 140 . Since the feed roller transmission gear 145 integrated with the pin wheel 150 rotates counterclockwise, the feed roller 11 meshing with it rotates clockwise.

The rotation of the paper feed roller 11 pushes the paper attached below to one side by means of friction. Once the leading edge of the paper is sufficiently close to the contact point of the transport roller 15 and the friction roller 17, the motor 80 rotates in the opposite direction.

The various gears that mesh with the gear set are forced to change direction due to the reverse rotation of the motor 80. When the idler wheel 120 turns counterclockwise, the protrusion 185 on the tab 181 collides with the other flange 190b of the ring 190 . The stop pin 180 is thus rotated clockwise, disengaging the lock gear 150 and stopping the operation of the feed roller. In addition, the conveying roller transmission gear 130 meshing with the idler 120 rotates clockwise, driving the conveying roller 15 to rotate counterclockwise, so that the paper is conveyed by the frictional force of the conveying roller 15 and the friction roller 17 .

When the present invention is adopted, the number of gears in the gear set required for the paper feeding operation of the printing equipment is significantly reduced, the structure is simplified, and thus the cost can be reduced.

While the preferred embodiment of the present invention has been described, those skilled in this document will find that various modifications, additions and substitutions are possible without departing from the scope and spirit of the invention as claimed.

Claims (3)

1. An automatic paper feeding device for printing equipment, said device comprising: a. Electric motor, which generates and transmits power; b, an idler, which meshes with a gear mounted on the rotating shaft of the motor; c, the transmission part of the conveying roller, which receives the power transmitted from the idler wheel to drive the conveying roller; and d. The transmission part of the paper feed roller, which drives the paper feed roller with the power transmitted intermittently by the idler wheel. 2. The automatic paper feeding device according to claim 1, wherein said paper feeding roller transmission part includes a locking gear and a locking pin to make said power transmission intermittent. 3. The automatic document feeder of claim 2, wherein said locking pin is selectively contactable with any one of the folded edges of a ring which is fitted in a groove of said locking gear.

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