JP3929955B2 - Image forming apparatus - Google Patents

Description

The present invention relates to an image forming apparatus such as an electrostatic copying machine or a laser printer. More specifically, an image is continuously formed on one side of a plurality of sheets, and a sheet on which an image is formed on one side is being conveyed. The present invention relates to an image forming apparatus that forms an image on the other side by re-feeding without stacking.

One typical example of the image forming apparatus of the above embodiment is an image forming conveyance path in which an image is formed on a conveyed sheet, and a sheet reversely carried in from the downstream side of the image forming conveyance path is carried out with the conveyance direction reversed. A reverse conveyance path, and a refeed conveyance path through which a sheet reversely carried out from the reverse conveyance path and re-inverted and conveyed is further reversed and re-introduced upstream of the image forming conveyance path. . At the upstream position of the image forming conveyance path, a registration roller is provided for temporarily waiting the sheet so that the sheet conveyance timing coincides with the image formation by the image forming unit. The refeed conveyance path is provided with four conveyance rollers and conveyance driving means for temporarily stopping and conveying a plurality of sheets of paper (see Patent Document 1).

According to the image forming apparatus, even when the waiting time of the sheet in the registration roller becomes longer than usual, it is possible to prevent the conveyed sheets from colliding with each other. However, four transport rollers are provided in the refeed transport path, and the transport driving means for temporarily stopping and waiting for the transport of a plurality of sheets independently drives the two transport rollers. Since it is composed of two stepping motors, the number of parts and the heat source increase, resulting in an increase in cost.

JP 2002-365862 A

An object of the present invention is to rotate and drive all of a plurality of conveying rollers by a single electric motor to continuously convey a sheet, and to rotate only some of the conveying rollers and to move other conveying rollers. Providing a novel image forming apparatus that can stop and temporarily stop the conveyance of a plurality of sheets and reduce the number of parts and the heat source and reduce the cost. is there.

According to the present invention,
An image forming conveyance path where an image is formed on the conveyed paper, a reverse conveyance path where paper conveyed in reverse from the downstream side of the image forming conveyance path is reversed and conveyed out, and reversely conveyed out from the reverse conveyance path. In addition, in the image forming apparatus including a re-feed conveyance path that is conveyed so that the re-reversed loaded paper is further reversed and re-loaded upstream of the image forming conveyance path.
In the refeed conveyance path, the first, second and third conveyance rollers are arranged in this order from upstream to downstream,
One end of the first transport roller is drivingly connected to one electric motor that can be rotated forward and backward via a one-way clutch so as to rotate in opposite directions, and one end of the second transport roller is connected to the electric motor via the one-way clutch. The other end of the first transport roller is connected to the other end of the second and third transport rollers via the one-way clutch so as to rotate in the same direction. Drive coupled,
When the electric motor is rotated forward, the one-way clutch disposed at one end of the first transport roller is disengaged, and the one-way clutch disposed at one end of the second transport roller is brought into contact to drive the electric motor. The force is transmitted to the other ends of the third transport roller and the first transport roller via the second transport roller, and the one-way clutch disposed at the other end of the first transport roller is brought into contact, and the first and second The second and third transport rollers are driven to rotate in the direction of transporting the paper;
When the electric motor is reversed, the one-way clutch disposed at one end of the first transport roller is brought into contact with the one-way clutch disposed at one end of the second transport roller and the other end of the first transport roller. The disposed one-way clutch is disengaged, the driving force of the electric motor is transmitted only to the first transport roller, the first transport roller is driven to rotate in the direction of transporting paper, and the second and third transport rollers Is stopped,
An image forming apparatus is provided.
A drive gear is integrally disposed on the drive shaft of the electric motor, a driven gear is disposed on one end of the first conveying roller via a one-way clutch, and a one-way clutch is disposed on the other end of the first conveying roller. A driven pulley is disposed at one end of the second conveying roller via a one-way clutch, and a driven pulley is integrally disposed at the other end of the second conveying roller. A driven pulley is integrally disposed at the other end of the third conveying roller, the driven gear of the first conveying roller is engaged with the driving gear, and the driven gear of the second conveying roller is the driving gear. In contrast, the driven pulleys of the first, second and third transport rollers are connected to each other via an endless timing belt so as to be rotated in the same direction via a power transmission mechanism. Drive to rotate in the direction Is sintered, it is preferable.
The power transmission mechanism includes a driven gear meshed with the drive gear and the driven pulley integrally disposed, and a driven gear meshed with the driven gear of the second conveying roller and integrally disposed with the driven pulley. It is preferable to include a gear and an endless timing belt wound around the driven pulley.

Preferred embodiments of an image forming apparatus constructed according to the present invention will be described below in detail with reference to the accompanying drawings.

Referring to FIG. 1, an electrostatic copier as an image forming apparatus includes a rectangular copier main body (not shown), and an image forming conveyance path 2 is provided in the copier main body in a lateral direction of the copier (see FIG. 1). 1 in the left-right direction). An image forming unit is also disposed in the copying machine main body in association with the image forming conveyance path 2. The image forming unit includes a photosensitive drum 4 and image forming elements such as a main charger, an exposure unit, a developing unit, a transfer belt mechanism 6, a cleaner, and a static eliminator arranged around the photosensitive drum 4. (Other than the transfer belt mechanism 6 is not shown). The image forming unit also includes a fixing device 8 disposed at a position downstream of the photosensitive drum 4 in the image forming conveyance path 2. A conveyance roller 12 and a registration roller 14 are arranged in that order from the upstream side to the downstream side of the image forming conveyance path 2 upstream of the photosensitive drum 4 (the position on the right side in FIG. 1). The transfer belt mechanism 6 is disposed in the image forming conveyance path 2 so as to face the outer peripheral surface of the photosensitive drum 4 from below the photosensitive drum 4. The fixing device 8 includes a heat roller and a pressure roller. A conveyance roller 16 is disposed at a position downstream of the fixing device 8 in the image forming conveyance path 2.

Image information read by a document reading device (not shown) disposed in the copying machine main body is irradiated onto the surface of the photosensitive drum 4 uniformly charged by the main charger by the exposure unit. An electrostatic latent image is formed on the surface of the photosensitive drum 4. This electrostatic latent image is developed by a developing device. On the other hand, the sheet conveyed by the conveying roller 12 is conveyed toward the transfer area formed by the photosensitive drum 4 and the transfer belt mechanism 6 at a predetermined timing by the registration roller 14. While the sheet passes through the transfer region, the development formed on the surface of the photosensitive drum 4 is transferred onto the one surface of the sheet facing upward by the transfer belt mechanism 6. The sheet on which the image is transferred on one side is conveyed to the fixing device 8 by the transfer belt mechanism 6, and the image is fixed on one side of the sheet while passing through the fixing device 8. The sheet on which the image is fixed on one side is conveyed further downstream by the conveying roller 16. As described above, an image is formed on one side of the upper side of the sheet while the sheet is conveyed through the image forming conveyance path 2.

The image forming conveyance path 2 is branched into a discharge path 18 and a reverse path 20 at a downstream position of the conveyance roller 16 that is the downstream end portion thereof. The discharge path 18 is disposed on the extension of the image forming conveyance path 2, and a discharge roller 22 is disposed at the downstream end of the discharge path 18. The reversing path 20 branches downward from the downstream end portion of the image forming conveyance path 2 and reverses and extends obliquely downward, and is connected to the reverse conveyance path 24. Carry-in rollers 26 and 27 are disposed in the reversing path 20. A branch claw 28 is disposed at a branch portion between the discharge path 18 and the reverse path 20. The branching claw 28 guides the sheet conveyed through the image forming conveyance path 2 toward the discharge path 18 by the actuator (not illustrated) and the first guiding position (not illustrated) that guides the sheet toward the reversing path 20. The two guide positions are selectively positioned. The reverse conveyance path 24 extends substantially horizontally in the lateral direction of the copying machine main body with an interval below the image forming conveyance path 2. A switchback roller 30 is disposed in a position near the exit of the reverse path 20 in the reverse transport path 24.

The reverse conveyance path 24 extends in the downstream direction of the image forming conveyance path 2 beyond the connection portion with the reversal path 20, and is reversed downward to be connected to the refeed conveyance path 32. The refeed conveyance path 32 extends substantially horizontally in the lateral direction of the copying machine main body with an interval below the reverse conveyance path 24. The reverse portion of the reverse conveyance path 24 includes a large-diameter reverse roller 34 and a small-diameter pressing roller 36 that is in pressure contact with the reverse roller 34. In the refeed conveyance path 32, first, second and third conveyance rollers 40, 42 and 44 are arranged in this order from upstream to downstream. The drive systems for the first, second and third transport rollers 40, 42 and 44 will be described later.

A paper feed conveyance path 45 is disposed at the right end in FIG. The paper feed conveyance path 45 extends substantially in the vertical direction and then extends linearly obliquely upward and is connected to a position immediately upstream of the conveyance roller 12, which is the upstream end of the image forming conveyance path 2. In the paper feed conveyance path 45, paper feed rollers 46, 47, 48, 49 are arranged in this order from upstream to downstream. The downstream area of the refeed conveyance path 32 is inclined upward and connected to the upstream side of the sheet feed roller 49 in the sheet feed conveyance path 45. Below the refeed conveyance path 32, a paper stacking tray 50, other paper stacking trays, and a paper feeding cassette are disposed (only the paper stacking tray 50 is shown in FIG. 1). In association with the paper stacking tray 50, a paper feed path 52, a pickup roller 54, a separation roller 56, and the like are disposed. The paper feed path 52 is connected to the paper feed conveyance path 45.

A reverse discharge path 60 is disposed between the downstream side of the nip portion of the reverse roller 34 and the pressing roller 36 in the reverse part of the reverse conveyance path 24 and the upstream side of the discharge roller 22 in the discharge path 18. ing. The reverse discharge path 60 is a discharge path for reversing a sheet having an image formed on one side and discharging the image surface downward and aligning the pages in order, and a reverse discharge roller 62 is also provided. A branching claw 64 is disposed at a branching portion between the reversing part of the reverse conveying path 24 and the reverse discharging path 60. The branching claw 64 guides the sheet switched back from the reverse conveyance path 24 by the actuator (not shown) to the reverse discharge path 60 and the refeed conveyance path 32. To the second guide position shown in the figure.

Only one sheet of paper loaded on the paper stacking tray 50 is sent to the paper feed path 52 by the pick-up roller 54 and the separation roller 56, and the image forming transport path 2 is passed through the paper feed transport path 45 by the paper feed rollers 48 and 49. And an image is formed on one side as described above. When the branching claw 28 is positioned at a first guide position (not shown), the paper conveyed through the image forming conveyance path 2 is discharged through the discharge path 18 to the discharge tray (not shown) with the image surface facing upward by the discharge roller 22. The When the branching claw 28 is positioned at the second guide position shown in FIG. 1, the sheet conveyed through the image forming conveyance path 2 is reversed to the reverse conveyance path 24 by the carry-in rollers 26 and 27 through the reversal path 20. It is carried in. The sheet carried into the reverse conveyance path 24 is sent to a predetermined position in the upstream direction of the image forming conveyance path 2 by the switchback roller 30 and stopped (the switchback roller 30 is one end of the sheet). Can be stopped with the nip in between).

Subsequently, when the switchback roller 30 is reversely rotated, the paper nipped by the switchback roller 30 (the image is turned upside down and the image surface faces downward) is conveyed reversely toward the nip portion between the reverse roller 34 and the pressing roller 36. The When the branching claw 64 is positioned at a first guide position (not shown), the sheet nipped by the reverse roller 34 and the pressing roller 36 is guided toward the reverse discharge path 60 and is shown by the reverse discharge roller 62 and the discharge roller 22. The paper is discharged with the image side down to the discharge tray.

When the branching claw 64 is positioned at the illustrated second guide position, the sheet nipped by the reversing roller 34 and the pressing roller 36 is re-reversed while moving along the outer peripheral surface of the reversing roller 34 and is re-feeded. It is carried into the paper conveyance path 32. The paper carried into the refeed conveyance path 32 is conveyed by the first, second, and third conveyance rollers 40, 42, and 44 with the image surface facing upward, with the front and back being reversed again, and the paper feed conveyance path 45. In this case, the paper is carried out to the upstream side of the paper feed roller 49 and is further reversed and carried into the image forming conveyance path 2. An image is formed on the other side of the sheet by the image forming unit while the sheet re-loaded into the image forming conveyance path 2 with the image side down is conveyed through the image forming conveyance path 2 again. The paper on which images are formed on both sides is guided by a branching claw 28 positioned at a first guide position (not shown), and is discharged through a discharge path 18 to a discharge tray (not shown) by a discharge roller 22.

The above is a description of the flow of a sheet when an image is formed on one side and both sides of one sheet. Next, images are formed on both sides while continuously conveying a plurality of sheets. The case will be described. The conveyance path for forming images on both sides is the same as described above. In this embodiment, from the paper feed roller 49, the conveyance roller 12, the registration roller 14, the carry-in rollers 26 and 27, and the switchback roller 30. In the conveying path to the reversing roller 34 and the pressing roller 36, the first, second and third conveying rollers 40, 42 and 44, four sheets of paper (JIS, A4 size paper: the width direction of the sheet is the conveying direction). Match) exists. Then, on the photosensitive drum 4, the order of image writing is as follows: first sheet table → second sheet table → third sheet table → first sheet back → fourth sheet table → second sheet table → fifth sheet table → 3rd sheet back → 6th sheet front → 4th sheet back → 7th sheet front → 5th sheet back.

As described above, when images are formed on both sides while continuously conveying a plurality of sheets, the sheets carried into the refeed conveyance path 32 are the first, second and third conveyance rollers 40, By rotating and driving 42 and 44, the sheet is conveyed at a predetermined conveyance speed. However, for example, when the amount of image writing on the photosensitive drum 4 is larger than usual, the standby time of the sheet in the registration roller 14 becomes longer than usual. In such a case, if the paper carried into the refeed conveyance path 32 is conveyed by rotating the first, second, and third conveyance rollers 40, 42, and 44 as usual, the paper is resupplied. There is a possibility that the paper re-introduced from the paper conveyance path 32 to the image forming conveyance path 2 may collide with the standby paper and cause jamming such as paper jam.

In the present invention, the first, second, and third transport rollers 40, 42, and 44 are rotated during normal transport by rotating one electric motor M that can rotate forward and backward in normal rotation. By rotating the motor M in the reverse direction, the two transport rollers 42 and 44 disposed on the downstream side of the refeed transport path 32 are temporarily stopped, and one of the transport rollers 42 and 44 disposed on the upstream side of the refeed transport path 32 is stopped. By rotating only the transport roller 40, the distance between the sheets can be adjusted between the transport roller 40 and the transport roller 42 (stop) disposed on the downstream side thereof. During this time, the heat roller and pressure roller, the conveyance roller 16, the carry-in rollers 26 and 27, the switchback roller 30 and the reverse roller 34 of the fixing device 8 are rotationally driven.

Hereinafter, the drive systems of the first, second, and third transport rollers 40, 42, and 44 disposed in the refeed transport path 32 will be described in detail.

Referring to FIGS. 2 and 1, a frame body 60 is disposed in the re-feed conveyance path 32. The frame 60 includes a bottom wall 62, a side wall 64 standing upright from one end portion (rear end portion in FIG. 2), and a side wall standing upright from the other end portion (front end portion in FIG. 2) of the bottom wall 62. 66. The first transport roller 40 includes a first transport driven roller 40A including a driven shaft 40a and two driven rollers 40b fixed to the driven shaft 40a, a driven shaft (not shown), and a driven shaft. A first transport driven roller 40B (see FIG. 1), which is composed of two fixed driven rollers (not shown), is provided. In FIG. 2, only the first transport driven roller 40A is shown. The two driven rollers of the first transport driven roller 40B are pressed against the corresponding driven roller 40b of the first transport driven roller 40A from below (the bottom wall 62 corresponding to the nip portion of these rollers). Is formed with an opening for preventing interference). The first transport driven roller 40A is rotatably supported between the side walls 64 and 66 via the driven shaft 40a. The first transport driven roller 40B is supported on the lower side of the bottom wall 62 so as to be rotatably and elastically urged upward by a stationary frame (not shown) of the copying machine main body.

The second transport roller 42 includes a second transport driven roller 42A including a driven shaft 42a and two driven rollers 42b fixed to the driven shaft 42a, a driven shaft (not shown), and a driven shaft. A second transport driven roller 42B (see FIG. 1), which is composed of two fixed driven rollers (not shown), is provided. In FIG. 2, only the second transport driven roller 42A is shown. The two driven rollers of the second transport driven roller 42B are pressed against the corresponding driven roller 42b of the second transport driven roller 42A from below (the bottom wall 62 corresponding to the nip portion of these rollers). Is formed with an opening for preventing interference). The second transport driven roller 42A is rotatably supported between the side walls 64 and 66 via the driven shaft 42a. The second transport driven roller 42B is supported on the lower side of the bottom wall 62 so as to be rotatably and elastically urged upward by a stationary frame (not shown) of the copying machine main body.

The third transport roller 44 includes a third transport driven roller 44A including a driven shaft 44a and two driven rollers 44b fixed to the driven shaft 44a, a driven shaft (not shown), and a driven shaft. Although a third transport driven roller 44B (see FIG. 1) composed of two driven rollers (not shown) that are fixed is provided, only the third transport driven roller 44A is shown in FIG. The two driven rollers of the third transport driven roller 44B are pressed against the corresponding driven roller 44b of the fourth transport driven roller 44A from below (to the bottom wall 62 corresponding to the nip portion of these rollers). Is formed with an opening for preventing interference). The fourth transport driven roller 44A is rotatably supported between the side walls 64 and 66 via a driven shaft 44a. The fourth transport driven roller 44B is supported on the lower side of the bottom wall 62 so as to be rotatably and elastically urged upward by a stationary frame (not shown) of the copying machine main body. As is clear from the above description, the refeed conveyance path 32 through which the sheet is conveyed extends from the left to the right in FIG. 2 along the lower surface of the bottom wall 62 of the frame 60.

The side wall 64 is provided with one electric motor M that can rotate forward and backward. A drive gear 72 is integrally disposed on the drive shaft 70 of the electric motor M. A driven gear 76 is disposed at one end of the driven shaft 40a of the first transport driven roller 40A via a one-way clutch 74. A driven pulley 80 is disposed via the one-way clutch 78 at the other end of the driven shaft 40a of the first transport driven roller 40A. A driven gear 84 is disposed through one-way clutch 82 at one end of driven shaft 42a of second transport driven roller 42A. A driven pulley 88 is integrally provided at the other end of the driven shaft 42a of the second transport driven roller 42A. A driven pulley 90 is integrally disposed at the other end portion of the driven shaft 44a of the third transport driven roller 44A.

The driven gear 76 of the first transport driven roller 40A is meshed with the driving gear 72 of the electric motor M. Thus, one end of the first transport driven roller 40A is drivingly connected to the driving gear 72 of the electric motor M via the one-way clutch 74 so as to rotate in opposite directions. The driven gear 84 of the second transport driven roller 42A is drivingly connected to the driving gear 72 of the electric motor M via the power transmission mechanism 92 so as to be rotated in the same direction. Between the driven pulleys 80, 88 and 90 of the first, second and third transport driven rollers 40A, 42A and 44A, a single endless timing belt 94 is wound and rotated in the same direction. Drive coupled. Thus, the other end of the first transport driven roller 40A is drivingly connected to the other end of the second and third transport driven rollers 42A and 44A via the one-way clutch 78 so as to rotate in the same direction. The The timing belt 94 is tensioned by tension pulleys 98 and 99 disposed on the side wall 66.

The power transmission mechanism 92 is wound between the driven pulleys 100 and 104 and the driven gear 102 in which the driven pulley 100 is integrally disposed, the driven gear 106 in which the driven pulley 104 is integrally disposed. The endless timing belt 108 is provided. The driven gears 102 and 106 are rotatably supported on the side wall 62. The driven gear 102 is meshed with the driving gear 72 of the electric motor M. The driven gear 106 is meshed with the driven gear 84 of the second transport driven roller 42A. The timing belt 108 is tensioned by a tension pulley 110 disposed on the side wall 62.

As is clear from the above description, the drive systems of the first, second and third transport rollers 40, 42 and 44 are specifically the first, second and third transport driven rollers 40A, 42A. However, it can be said that the first, second, and third transport rollers 40, 42, and 44 are substantially disposed. Therefore, in the present invention, one end portions of the first and second transport rollers 40 and 42 are drivingly connected to one electric motor M that can be rotated forward and backward via the one-way clutches 74 and 82, respectively. It can be said that the other end of 40 is drivingly connected to the other ends of the second and third transport rollers 42 and 44 via the one-way clutch 78 so as to rotate in the same direction.

Referring to FIG. 3, when electric motor M is rotated forward (counterclockwise in FIG. 3), one-way clutch 74 disposed at one end of first transport driven roller 40A is disengaged, and second The one-way clutch 82 disposed at one end of the transport driven roller 42A and the one-way clutch 78 disposed at the other end of the first transport driven roller 40A are in contact. As a result, since the driving force of the electric motor M is transmitted to the first and third transport driven rollers 40A and 44A via the second transport driven roller 42A, the first, second and third transport driven rollers are transmitted. All of the rollers 40A, 42A and 44A are driven to rotate in the direction in which the paper is conveyed (counterclockwise in FIG. 3). That is, all of the first, second, and third transport rollers 40, 42, and 44 are rotationally driven in the direction in which the paper is transported.

Referring to FIG. 4, when the electric motor M is reversely rotated, the one-way clutch 74 disposed at one end of the first transport driven roller 40A comes into contact, and is disposed at one end of the second transport driven roller 42A. The one-way clutch 82 and the one-way clutch 78 disposed at the other end of the first transport driven roller 40A are disconnected. As a result, since the driving force of the electric motor M is transmitted only to the first transport driven roller 40A, only the first transport driven roller 40A is driven to rotate in the direction in which the paper is transported. The transport driven rollers 42A and 44A are stopped. That is, only the first transport roller 40 is driven to rotate in the direction of transporting the paper, and the second and third transport rollers 42 and 44 are stopped.

As described above, according to the image forming apparatus of the present invention, a plurality of, in the embodiment, the three transport rollers 40, 42, and 44 disposed in the refeed transport path 32 are formed by one electric motor M. All of them are rotationally driven to continuously convey the sheet, and in the embodiment, a part of the conveying rollers disposed at the most upstream position in the refeed conveyance path 32, in the refeed conveyance path 32 in the embodiment. Only the transport roller 40 disposed at the most upstream position is rotationally driven and the other transport rollers 42 and 44, in the embodiment, the other transport roller 42 disposed downstream of the transport roller 40 in the refeed transport path 32 and 44 is stopped, so that the conveyance of a plurality of sheets can be temporarily stopped and kept on standby.

That is, as described above, when an image is formed on both sides while continuously conveying a plurality of sheets, when the waiting time of the sheet in the registration roller 14 is normal, the electric motor M is rotated forward. By doing so, all of the first, second and third transport rollers 40, 42 and 44 can be rotationally driven. As a result, the sheet carried into the refeed conveyance path 32 is continuously conveyed at a predetermined conveyance speed, and images can be formed on both sides of the sheet efficiently and continuously.

However, for example, when the paper standby time in the registration roller 14 becomes longer than usual due to the amount of image writing on the photosensitive drum 4 being larger than usual, the electric motor M is temporarily turned on. Only by reversing, the two transport rollers 42 and 44 disposed on the downstream side of the refeed transport path 32 are temporarily stopped, and one transport roller disposed on the upstream side of the refeed transport path 32 Only 40 can be rotated. As a result, the sheet in the refeed conveyance path 32 following the sheet waited on the registration roller 14 is temporarily stopped, while the conveyance roller 40 and the conveyance roller 42 disposed downstream thereof (stop) )), The distance between the sheets can be adjusted. As a result, it is possible to reliably prevent a sheet re-loaded from the re-feed conveyance path 32 into the image forming conveyance path 2 from colliding with a waiting sheet and causing a jam such as a paper jam. In addition, since the plurality of transport rollers 40, 42, and 44 disposed in the refeed transport path 32 can be driven and controlled by one electric motor M that can rotate forward and backward, the number of parts and heat generation can be increased as compared with the conventional apparatus. Reduce costs and reduce costs. If three transport rollers are provided in the refeed transport path 32, the number of transport rollers is reduced by one compared to the conventional apparatus, the number of parts is further reduced, and the overall apparatus is compact. It becomes possible.

In the above-described embodiment, three transport rollers 40, 42, and 44 are disposed in the refeed transport path 32, but four or more transport rollers are connected to one transport roller. By rotating the electric motor M forward and backward, all of the transport rollers are rotationally driven to transport the paper continuously, while only some of the transport rollers are rotationally driven and the other transport rollers are stopped, so that a plurality of sheets It is possible to temporarily stop the conveyance of the paper and wait. In this case, the number of transport rollers is the same as that of the conventional apparatus, but since the drive control can be performed by one electric motor M, it goes without saying that the above-described advantages are ensured for the conventional apparatus. Absent.

1 is a schematic cross-sectional view showing the main components of a preferred embodiment of an image forming apparatus configured according to the present invention. FIG. 2 is a schematic perspective view illustrating a conveyance roller disposed in a refeed conveyance path illustrated in FIG. 1 and a drive system of the conveyance roller. FIG. 3 is an explanatory diagram illustrating one operation mode of a conveyance roller and a conveyance roller drive system illustrated in FIG. 2. FIG. 4 is an explanatory diagram illustrating another operation mode of the conveyance roller and the conveyance roller drive system illustrated in FIG. 2.

Explanation of symbols

2: image forming conveyance path 20: reverse path 24: reverse conveyance path 32: refeed conveyance path 40: first conveyance roller 40A: first conveyance driven roller 40a: driven shaft 40a: driven roller 42: second Transport roller 42A: second transport driven roller 42a: driven shaft 42a: driven roller 44: third transport roller 44A: third transport driven roller 44a: driven shaft 44a: driven roller 70: drive shaft 72: Drive gear 74: One-way clutch 76: Driven gear 78: One-way clutch 80: Driven pulley 82: One-way clutch 84: Driven gear 88: Driven pulley 90: Driven pulley M: Electric motor

Claims (3)

An image forming conveyance path where an image is formed on the conveyed paper, a reverse conveyance path where paper conveyed in reverse from the downstream side of the image forming conveyance path is reversed and conveyed out, and reversely conveyed out from the reverse conveyance path. In addition, in the image forming apparatus including a re-feed conveyance path that is conveyed so that the re-reversed loaded paper is further reversed and re-loaded upstream of the image forming conveyance path.
In the refeed conveyance path, the first, second and third conveyance rollers are arranged in this order from upstream to downstream,
One end of the first transport roller is drivingly connected to one electric motor that can be rotated forward and backward via a one-way clutch so as to rotate in opposite directions, and one end of the second transport roller is connected to the electric motor via the one-way clutch. The other end of the first transport roller is connected to the other end of the second and third transport rollers via the one-way clutch so as to rotate in the same direction. Drive coupled,
When the electric motor is rotated forward, the one-way clutch disposed at one end of the first transport roller is disengaged, and the one-way clutch disposed at one end of the second transport roller is brought into contact to drive the electric motor. The force is transmitted to the other ends of the third transport roller and the first transport roller via the second transport roller, and the one-way clutch disposed at the other end of the first transport roller is brought into contact, and the first and second The second and third transport rollers are driven to rotate in the direction of transporting the paper;
When the electric motor is reversed, the one-way clutch disposed at one end of the first transport roller is brought into contact with the one-way clutch disposed at one end of the second transport roller and the other end of the first transport roller. The disposed one-way clutch is disengaged, the driving force of the electric motor is transmitted only to the first transport roller, the first transport roller is driven to rotate in the direction of transporting paper, and the second and third transport rollers Is stopped,
An image forming apparatus. A drive gear is integrally disposed on the drive shaft of the electric motor, a driven gear is disposed on one end of the first conveying roller via a one-way clutch, and a one-way clutch is disposed on the other end of the first conveying roller. A driven pulley is disposed at one end of the second conveying roller via a one-way clutch, and a driven pulley is integrally disposed at the other end of the second conveying roller. A driven pulley is integrally disposed at the other end of the third conveying roller, the driven gear of the first conveying roller is engaged with the driving gear, and the driven gear of the second conveying roller is the driving gear. In contrast, the driven pulleys of the first, second and third transport rollers are connected to each other via an endless timing belt so as to be rotated in the same direction via a power transmission mechanism. Drive to rotate in the direction Is sintered, the image forming apparatus according to claim 1. The power transmission mechanism includes a driven gear meshed with the drive gear and the driven pulley integrally disposed, and a driven gear meshed with the driven gear of the second conveying roller and integrally disposed with the driven pulley. The image forming apparatus according to claim 2 , further comprising a gear and an endless timing belt wound around the driven pulley.

Images