JP2024093920A - Paper feeder and image forming apparatus - Google Patents

Abstract

To provide a paper feeding device that can pinch multiple locations on a sheet of paper and convey it while preventing the paper from skewing.SOLUTION: A paper feeding device 18 of the invention includes: a paper feeding shaft 42 which feeds paper sandwiched between a paper feeding roller 41 and a separation roller 43 which are rotationally driven, conveys a sheet of paper to an image forming part, is connected to a driving source, and has a paper feeding roller 41 attached thereto; a plurality of paper feeding auxiliary rollers 44 attached to the paper feeding shaft 42; and a driven roller 45 which abuts on the paper feeding auxiliary roller 44. The sheet is conveyed while being held between the paper feeding auxiliary roller 44 and the driven roller 45, and the pressing force by which the driven roller 45 presses the paper feeding auxiliary roller 44 is larger than the pressing force by which the separation roller 43 presses the paper feeding roller 41.SELECTED DRAWING: Figure 1

Description

This disclosure relates to a paper feeder that feeds clamped paper and an image forming device.

Conventionally, image forming devices are provided with a paper feed section (paper feeder) capable of storing multiple sheets of paper, thereby reducing the number of times paper needs to be refilled and saving the user time. In recent years, image forming devices have been made more compact, and paper feeders with a reduced number of parts such as rollers have been proposed (see, for example, Patent Document 1 and Patent Document 2).

JP 2003-335426 A

A conventional paper feed device has a paper feed cassette that stores paper, a paper feed roller that contacts the paper stored in the paper feed cassette, multiple driven rollers arranged near the paper feed roller, and a guide means that guides the paper.

In the above-mentioned paper feed device, only one feed roller (paper feed roller) is provided at a position corresponding to the center of the paper in the width direction, and there is no member for pressing both ends of the paper in the width direction. Therefore, there is a risk that the paper will be skewed due to uneven load on the paper when it is transported.

The present disclosure has been made to solve the above problems, and aims to provide a paper feeder and image forming device that can clamp the paper at multiple points and transport the paper while preventing it from skewing.

The paper feed device disclosed herein is a paper feed device that feeds paper sandwiched between a rotationally driven paper feed roller and a separation roller, and transports the paper to an image forming unit, and is equipped with a paper feed shaft connected to a drive source and to which the paper feed roller is attached, a plurality of paper feed auxiliary rollers attached to the paper feed shaft, and a driven roller that abuts against the paper feed auxiliary roller, and is characterized in that the paper is sandwiched between the paper feed auxiliary roller and the driven roller and transported, and the pressure with which the driven roller presses against the paper feed auxiliary roller is greater than the pressure with which the separation roller presses against the paper feed roller.

In the paper feed device disclosed herein, the position where the driven roller presses against the paper feed auxiliary roller may be downstream in the direction of transporting the paper to the image forming unit from the position where the separation roller presses against the paper feed roller.

The paper feed device according to the present disclosure may be configured to include a contact roller that contacts the paper feed roller to clamp the paper.

In the paper feed device according to the present disclosure, the paper feed shaft extends along the width direction of the paper, the paper feed roller is provided in the center of the paper feed shaft in the width direction, and the paper feed auxiliary rollers are provided at two locations in the width direction, sandwiching the paper feed roller therebetween.

In the paper feed device disclosed herein, the paper feed auxiliary roller may be attached to the paper feed shaft via a one-way clutch, and the one-way clutch may be configured to transmit force to the paper feed auxiliary roller when the paper feed shaft rotates in the direction of transporting paper to the image forming unit.

The paper feed device according to the present disclosure may be configured such that, in the circumferential direction around the axis of the paper feed shaft, an angle formed by a line passing through the paper feed shaft and the center of the separation roller and a line passing through the paper feed shaft and the center of the driven roller is 90 degrees or more.

The image forming device according to the present disclosure is characterized by being equipped with the paper feed device according to the present disclosure.

According to the present disclosure, the paper can be conveyed while preventing skewing by clamping the paper at multiple points between the paper feed auxiliary roller and the driven roller.

1 is a schematic configuration diagram of an image forming apparatus according to a first embodiment of the present disclosure. FIG. 2 is a schematic perspective view showing a structure around a paper feed roller. FIG. 2 is a schematic side view showing a structure around the paper feed roller. FIG. 11 is a schematic perspective view showing a structure around a paper feed roller in an image forming apparatus according to a second embodiment of the present disclosure. FIG. 11 is a schematic perspective view showing a structure around a paper feed roller in an image forming apparatus according to a third embodiment of the present disclosure. FIG. 11 is a schematic side view (part 1) showing a structure around a paper feed roller in an image forming apparatus according to a third embodiment of the present disclosure. FIG. 13 is a schematic side view (part 2) showing a structure around the paper feed roller in an image forming apparatus according to a third embodiment of the present disclosure. FIG. 13 is a schematic side view (part 3) showing a structure around a paper feed roller in an image forming apparatus according to a third embodiment of the present disclosure.

First Embodiment
Hereinafter, an image forming apparatus according to a first embodiment of the present disclosure will be described with reference to the drawings.

Figure 1 is a schematic diagram of an image forming apparatus according to a first embodiment of the present disclosure.

The image forming apparatus 1 according to the first embodiment of the present disclosure is configured to include an exposure device 11, a development device 12, a photoconductor drum 13 (an example of a toner image carrier), a cleaning device 14, a charger 15, an intermediate transfer belt device 16, a fixing device 17, a paper feed device 18, a paper output tray 19, and a paper transport path S, and forms multi-color and monochrome images on a specified paper sheet according to image data transmitted from the outside.

The image data handled by the image forming device 1 corresponds to a color image using the colors black (K), cyan (C), magenta (M), and yellow (Y). Therefore, four developing devices 12, photoconductor drums 13, chargers 15, and cleaning devices 14 are provided to form four types of latent images corresponding to each color, and are set to black, cyan, magenta, and yellow, respectively, and these constitute four image stations Fa, Fb, Fc, and Fd.

The photoconductor drum 13 is disposed approximately in the center of the image forming apparatus 1. The charger 15 uniformly charges the surface (circumferential surface) of the photoconductor drum 13 to a predetermined potential. The exposure device 11 exposes the surface of the photoconductor drum 13 to light to form an electrostatic latent image. The development device 12 develops the electrostatic latent image on the surface of the photoconductor drum 13 to form a toner image on the surface of the photoconductor drum 13. Through the above-mentioned series of operations, a toner image of each color is formed on the surface of each photoconductor drum 13. The cleaning device 14 removes and collects residual toner on the surface of the photoconductor drum 13 after development and image transfer. The structure around the photoconductor drum 13 will be described in detail later with reference to FIG. 2.

The intermediate transfer belt device 16 is disposed above the photosensitive drum 13 and includes an intermediate transfer belt 21, an intermediate transfer belt drive roller 22, an intermediate transfer belt driven roller 23, an intermediate transfer roller 24, and an intermediate transfer belt cleaning device 25. There are four intermediate transfer rollers 24, one for each of the image stations for YMCK.

The intermediate transfer belt drive roller 22, the intermediate transfer belt driven roller 23, and the intermediate transfer roller 24 are configured to tension the intermediate transfer belt 21 and move the surface of the intermediate transfer belt 21 in a predetermined direction (the direction of the arrow C in the figure).

The intermediate transfer belt 21 rotates in the direction of the arrow C, and residual toner is removed and collected by the intermediate transfer belt cleaning device 25. The toner images of each color formed on the surface of each photoconductor drum 13 are transferred and superimposed in sequence to form a color toner image on the surface of the intermediate transfer belt 21.

The image forming device 1 further includes a secondary transfer device 26 that includes a transfer roller 26a. A nip area is formed between the transfer roller 26a and the intermediate transfer belt 21, and the paper conveyed through the paper conveying path S is sandwiched in the nip area and conveyed. When the paper passes through the nip area, the toner image on the surface of the intermediate transfer belt 21 is transferred to the paper.

The paper feed device 18 is provided below the exposure device 11 and has a loading plate 18a on which paper to be used for image formation is loaded. It is provided below the exposure device 11. The paper discharge tray 19 is provided above the image forming device 1 and is a tray for placing paper on which an image has been formed.

The paper transport path S includes a main path S1 that is formed in an S-shape, and a reversing path S2 that branches off and rejoins the main path S1 midway. Along the main path S1, the paper feed roller 41, the pre-registration roller 33, the registration roller 32, the secondary transfer device 26, the fixing device 17, and the paper discharge roller 34 are arranged. The reversing path S2 branches off between the fixing device 17 and the paper discharge roller 34, and passes through a number of transport rollers 35 before rejoining between the pre-registration roller 33 and the registration roller 32.

The paper feed roller 41 is provided near the end of the stack plate 18a and is a pickup roller that feeds the paper from the stack plate 18a one sheet at a time to the paper transport path S. The stack plate 18a lifts the stacked paper and brings the topmost paper into contact with the paper feed roller 41. The registration roller 32 temporarily holds the paper being transported from the paper feed tray 18 and transports the paper to the transfer roller 26a at a timing that aligns the leading edge of the toner image on the photosensitive drum 13 with the leading edge of the paper. The pre-registration roller 33 is a small roller that assists in facilitating the transport of the paper. The structure around the paper feed roller 41 will be described later with reference to Figures 2 and 3.

The fixing device 17 uses a belt fixing method, with a belt wound around two rollers and an additional roller that applies pressure via the belt. The fixing device 17 receives the paper on which an unfixed toner image has been formed, and conveys the paper by sandwiching it between the rollers via the belt. After fixing, the paper is discharged onto the paper discharge tray 19 by the paper discharge rollers 34.

When forming an image on the back side of the paper as well as the front side, the paper is transported in the opposite direction from the discharge rollers 34 to the inversion path S2, the paper is inverted, and the paper is guided again to the registration rollers 32, where an image is formed on the back side in the same manner as on the front side, and the paper is then discharged to the discharge tray 19.

Next, the structure around the paper feed roller 41 will be described with reference to Figures 2 and 3.

Figure 2 is a schematic perspective view showing the structure around the paper feed roller, and Figure 3 is a schematic side view showing the structure around the paper feed roller.

The paper feed device 18 is structured to feed paper sandwiched between the rotating paper feed roller 41 and the separation roller 43 and transport it to the image forming section. In this embodiment, the image forming section corresponds to the nip area between the transfer roller 26a and the intermediate transfer belt 21. The paper feed device 18 is provided with a paper feed shaft 42 connected to a drive source (not shown), and the paper feed roller 41 is attached to the paper feed shaft 42. The paper feed shaft 42 extends along the width direction W of the paper P, and the paper feed roller 41 is provided at the center of the paper feed shaft 42 in the width direction W. In other words, the paper feed roller 41 and the separation roller 43 are provided at a position where they sandwich the center of the paper P in the width direction W. The separation roller 43 is urged by a separation urging member 43a to press the paper feed roller 41.

In addition, a plurality of auxiliary feed rollers 44 having the same outer shape as the feed roller 41 are attached to the feed shaft 42. A driven roller 45 is provided facing the auxiliary feed roller 44, and the driven roller 45 abuts against the auxiliary feed roller 44. In the embodiment disclosed herein, the auxiliary feed roller 44 is provided at two locations sandwiching the feed roller 41 in the width direction W. In other words, the auxiliary feed roller 44 and the driven roller 45 are provided at both ends of the feed shaft 42 in the width direction W. In other words, the auxiliary feed roller 44 and the driven roller 45 are provided at positions that sandwich both ends of the paper P in the width direction W. The driven roller 45 is biased by the driven biasing member 45a so as to press the auxiliary feed roller 44. In this way, by clamping the paper P at multiple locations between the auxiliary feed roller 44 and the driven roller 45, the paper P can be transported while preventing it from skewing.

As described above, in the width direction W, the paper feed roller 41 is provided at the center of the paper feed shaft 42, and the paper feed auxiliary rollers 44 are provided at two locations sandwiching the paper feed roller 41. In this way, the paper feed roller 41 holds the center of the paper P, while the paper feed auxiliary rollers 44 hold both ends of the paper P, so that skewing of the paper P can be more reliably prevented.

The pressure with which the driven roller 45 presses against the paper feed auxiliary roller 44 is set to be greater than the pressure with which the separation roller 43 presses against the paper feed roller 41.

In small multifunction machines, due to space issues in the paper feed section, the separation roller 43 is placed in contact with the paper feed roller 41 (pickup roller) to pick up and separate the paper P. The paper P is sandwiched between the paper feed roller 41 and the separation roller 43, and is transported to the next roller (for example, the pre-registration roller 33) by the rotation of the paper feed roller 41.

However, in a small multifunction printer, it is difficult to provide other transport rollers between the feed roller 41 and the pre-registration roller 33 due to cost and space constraints. Furthermore, since the pressure between the feed roller 41 and the separation roller 43 is set to an optimum pressure for separating the paper, depending on the environmental conditions, paper slippage may occur during transport, causing delays in transport to subsequent rollers after feeding, resulting in failure to keep up with image formation, or making it impossible to transport the paper at high speed even if desired.

In the paper feed device 18 of the present disclosure, a driven roller 45 with a higher pressing force than the separation roller 43 is provided, which prevents the paper from slipping during transport and ensures that the paper P is transported to the pre-registration roller 33.

Figure 3 shows the vicinity of the paper feed roller 41 as viewed in the direction along the paper feed shaft 42. As shown in Figure 3, in the circumferential direction R around the axis of the paper feed shaft 42, the separation roller 43 is provided near the tip of the stacking plate 18a in the raised state. In other words, the paper P pushed up by the stacking plate 18a is fed in with its tip sandwiched between the paper feed roller 41 and the separation roller 43.

The driven roller 45 is in contact with the paper feed auxiliary roller 44, and is disposed so as to be downstream of the separation roller 43 in the transport direction in which the paper P is transported. In other words, the driven roller 45 is disposed at a position where, when the paper P is transported from the paper feed device 18, it passes through the nip between the paper feed roller 41 and the separation roller 43, and then reaches the nip between the paper feed auxiliary roller 44 and the driven roller 45.

3 indicates a straight line passing through the center of the paper feed shaft 42 and the separation roller 43, and the second auxiliary line SL2 indicates a straight line passing through the center of the paper feed shaft 42 and the driven roller 45. In the embodiment of the present disclosure, the angle between the first auxiliary line SL1 and the second auxiliary line SL2 is set to 90 degrees or more. As described above, since the direction in which the separation roller 43 presses the paper feed shaft 42 and the direction in which the driven roller 45 presses the paper feed shaft 42 are different, the paper feed shaft 42 is prevented from being pressed significantly in one direction, and the paper feed shaft 42 is prevented from bending and causing problems in transporting the paper. In addition, since the angle between the separation roller 43 and the driven roller 45 is 90 degrees or more, the forces from the two are prevented from strengthening each other.

Second Embodiment
Next, an image forming apparatus according to a second embodiment of the present disclosure will be described with reference to the drawings. Note that the image forming apparatus according to the second embodiment is substantially the same as the first embodiment shown in Figures 1 to 3, so the same reference numerals are used and the description and drawings are omitted.

Figure 4 is a schematic perspective view showing the structure around the paper feed roller in an image forming device according to the second embodiment of the present disclosure.

The second embodiment differs from the first embodiment in that a contact roller 46 is provided. The contact roller 46 is provided in contact with the feed roller 41 and clamps the paper together with the feed roller 41. When viewed from the same perspective as in FIG. 3, the contact roller 46 is provided at a position overlapping the driven roller 45 in the circumferential direction R. In other words, the feed roller 41 clamps and pulls in the paper P together with the separation roller 43, and as the paper is transported forward, the part of the paper beyond the part clamped by the separation roller 43 is clamped together with the contact roller 46. In this way, by adding the contact roller 46 that clamps the paper, the transport force can be further improved.

The position of the driven roller 45 is not limited to this, and may be located in a different position as long as it does not interfere with the separation roller 43, and may be located in a position that does not overlap with the driven roller 45. The contact roller 46 is biased by the contact biasing member 46a to press against the paper feed roller 41, similar to the separation roller 43.

Third Embodiment
Next, an image forming apparatus according to a third embodiment of the present disclosure will be described with reference to the drawings. Note that the image forming apparatus according to the third embodiment is substantially the same as the first and second embodiments shown in Figures 1 to 4, and therefore the same reference numerals are used and the description and drawings are omitted.

Figure 5 is a schematic perspective view showing the structure around the paper feed roller in an image forming device according to the third embodiment of the present disclosure.

The third embodiment differs from the first embodiment in that the paper feed auxiliary roller 44 is attached to the paper feed shaft 42 via a one-way clutch 47. The one-way clutch 47 transmits force to the paper feed auxiliary roller 44 when the paper feed shaft 42 rotates in the transport direction in which the paper P is transported to the image forming unit. The movement of the paper feed roller 41 and the paper feed auxiliary roller 44 when the paper P is transported by the paper feed device 18 will be described with reference to Figures 6 to 8.

Figure 6 is a schematic side view (part 1) showing the structure around the paper feed roller in an image forming device according to the third embodiment of the present disclosure.

As described above, when an instruction to start feeding is given, the drive unit drives the feed shaft 42 counterclockwise in FIG. 6, and the feed roller 41 fixed to the feed shaft 42 rotates counterclockwise. Then, the paper P that has been pushed up by the stacking plate 18a and is in contact with the feed roller 41 is transported to the right side in FIG. 6 as the feed roller 41 rotates counterclockwise, and the leading edge (paper leading edge Pa) is pinched and pulled in by the feed roller 41 and separation roller 43, and the paper P is transported by the feed roller 41 and separation roller 43.

At this time, the one-way clutch 47 is in the direction of transmitting rotation to the paper feed auxiliary roller 44, so the paper feed auxiliary roller 44 is also rotating counterclockwise.

Figure 7 is a schematic side view (part 2) showing the structure around the paper feed roller in an image forming device according to the third embodiment of the present disclosure.

Figure 7 shows the state in which the paper feed shaft 42 is driven counterclockwise by the drive unit from the state shown in Figure 6, transporting the paper P forward. When the paper P is transported forward from the state shown in Figure 6, the leading edge Pa of the paper that has reached the paper feed auxiliary roller 44 and the driven roller 45 is clamped, and the paper P is transported by the paper feed auxiliary roller 44 that is rotating. In this state, the paper feed roller 41 and the separation roller 43 clamp the paper slightly rearward of the leading edge Pa.

Figure 8 is a schematic side view (part 3) showing the structure around the paper feed roller in an image forming device according to the third embodiment of the present disclosure.

Figure 8 shows the state in which the paper P has been transported further from the state shown in Figure 7. When the paper P is transported further from the state shown in Figure 7, the rear end Pb of the paper passes through the paper feed roller 41 and the separation roller 43, and the vicinity of the rear end Pb of the paper is clamped between the paper feed auxiliary roller 44 and the driven roller 45. In addition, a portion of the paper P transported further reaches the pre-registration roller 33.

When a part of the paper P reaches the pre-registration roller 33, the pre-registration roller 33 can be driven to transport the paper P, and the paper feed shaft 42 may be stopped. In the state shown in FIG. 8, the paper P transported earlier is not sandwiched between the paper feed roller 41 and the separation roller 43, but is sandwiched between the paper feed auxiliary roller 44 and the driven roller 45. When the paper P is transported in this state, the paper feed roller 41 does not rotate, but the paper feed auxiliary roller 44 rotates. At this time, since the paper feed auxiliary roller 44 is attached to the paper feed shaft 42 via the one-way clutch 47, even if the paper feed shaft 42 is stopped, only the paper feed auxiliary roller 44 rotates, and the paper P is not loaded and can be transported smoothly. In addition, since the paper feed shaft 42 is stopped and the paper feed roller 41 does not rotate, new paper P is not drawn in, and the timing of supplying the paper P can be appropriately controlled.

The embodiments disclosed herein are illustrative in all respects and are not intended to be a basis for restrictive interpretation. Therefore, the technical scope of this disclosure is not to be interpreted solely by the embodiments described above, but is defined based on the claims. Furthermore, all modifications within the scope and meaning equivalent to the claims are included.

REFERENCE SIGNS LIST 1 image forming apparatus 18 paper feed apparatus 18a stacking plate 41 paper feed roller 42 paper feed shaft 43 separation roller 43a separation biasing member 44 paper feed auxiliary roller 45 driven roller 45a driven biasing member 46 contact roller P paper Pa paper leading edge Pb paper trailing edge R circumferential direction W width direction

Claims (7)

A paper feed device that feeds paper sandwiched between a rotationally driven paper feed roller and a separation roller and transports the paper to an image forming unit,
a paper feed shaft connected to a drive source and having the paper feed roller attached thereto;
A plurality of auxiliary paper feed rollers attached to the paper feed shaft;
a driven roller in contact with the paper feed auxiliary roller,
The paper is conveyed by being sandwiched between the paper feed auxiliary roller and the driven roller,
A paper feeding device according to claim 1, wherein a pressing force applied by said driven roller to said paper feed auxiliary roller is greater than a pressing force applied by said separation roller to said paper feed roller. 2. The paper feeder according to claim 1,
a position where the driven roller presses against the paper feed auxiliary roller is downstream in a direction in which the paper is transported to the image forming unit from a position where the separation roller presses against the paper feed roller. 2. The paper feeder according to claim 1,
The paper feed device further comprises a contact roller that contacts the paper feed roller to hold the paper therebetween. 2. The paper feeder according to claim 1,
The paper feed shaft extends along the width direction of the paper,
the paper feed roller is provided at a center of the paper feed shaft in the width direction,
The paper feeding device according to the present invention, wherein the paper feed auxiliary rollers are provided at two positions in the width direction, sandwiching the paper feed roller therebetween. 2. The paper feeder according to claim 1,
The paper feed auxiliary roller is attached to the paper feed shaft via a one-way clutch,
The one-way clutch transmits force to the auxiliary paper feed roller when the paper feed shaft rotates in a direction in which the paper is transported to the image forming unit. 2. The paper feeder according to claim 1,
a paper feed device characterized in that, in a circumferential direction around the paper feed shaft, an angle formed by a straight line passing through the paper feed shaft and the center of the separation roller and a straight line passing through the paper feed shaft and the center of the driven roller is 90 degrees or more. An image forming apparatus equipped with the paper feeder according to claim 1.

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