JP2002145537A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To adjust a drive mechanism for the normal rotation of delivery roll with the basic structure only and a drive mechanism both for the normal rotation and reverse rotation of the delivery roll when optional mechanisms are attached in an image forming device for forming an image consisting of a fixing toner image on a paper sheet. SOLUTION: A reverse carrier unit, for taking in a paper sheet delivered on the way temporarily by the normal rotation of the issue roll again by the reverse rotation of the delivery roll to issue the paper sheet, can be mounted on the image forming device, and transmission of the driving force of the drive source through the first drive passage of the image forming device is cut by mounting the reverse carrier unit. The reverse carrier unit has a second drive passage for transmitting the driving force of the drive source to the delivery roll in such a way that the delivery can be rotated both in the normal and reverse directions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for forming an image comprising a fixed toner image on paper.

[0002]

2. Description of the Related Art Conventionally, the above-mentioned image forming apparatus has been widely used in, for example, laser printers and copiers. In an image forming apparatus of this type, usually, a sheet is conveyed along a predetermined sheet conveying path, and in the middle of the conveyance, an image bearing member having a toner image on the surface thereof undergoes a predetermined toner image forming process. After the toner image is transferred onto the paper being conveyed, the paper on which the toner image has been transferred is further conveyed and the toner image is fixed on the paper, and then disposed at the most downstream portion of the paper conveyance path. The paper is discharged out of the machine by the discharged roll.

In the case of an image forming apparatus configured as described above, a drive source such as a motor for driving the discharge roll is expensive and large in size if only the drive of the discharge roll is driven. A single motor is configured to drive the image carrier and also drive a sheet conveying member other than the discharge rolls that conveys the sheet along the sheet conveying path.

[0004]

By the way, in the above-described image forming apparatus, depending on the user, paper may be used.
There is a need to discharge paper in a direction other than the above-described discharge roll, and a need to form images on both sides of a sheet. In order to meet such needs, if a mechanism that satisfies these needs is incorporated as a basic configuration of the apparatus from the beginning, an expensive apparatus incorporating a mechanism unnecessary for a user who does not have such needs is required. For this reason, it is considered that the basic configuration of the device is configured to be able to be added as an option without responding to such needs.

[0005] In such a configuration, the above-described discharge roll may be rotated only in a direction for discharging the paper out of the machine (a rotation in this direction is referred to as a forward rotation herein) in a basic configuration. When the optional mechanism that satisfies the needs described above is installed, it is necessary to convey the paper that has been ejected partway out of the machine by rotating the ejection roll in the reverse direction, as well as the normal rotation. There are cases.

In such a configuration, if an attempt is made to allow the discharge roll to rotate in both the forward rotation and the reverse rotation in the basic configuration of the apparatus, for example, the discharge roll is moved from a motor as a driving source to a discharge roll. In such a case, a clutch mechanism is provided on the drive path leading to the motor. In this case, a user who needs only with the basic configuration includes a useless mechanism. May be changed.

On the other hand, it is conceivable to rotate the discharge roll in both the forward rotation and the reverse rotation by driving the discharge roll from the mechanism side as an option. In this case, however, the discharge provided in the basic structure is considered. The problem is how to adjust the gap between the roll and the drive mechanism.

In view of the above circumstances, the present invention adjusts a drive mechanism for rotating the discharge roll in the forward direction when only the basic configuration is provided, and a mechanism for driving the discharge roll in the forward and reverse directions when the optional mechanism is mounted. It is an object of the present invention to provide an image forming apparatus.

[0009]

An image forming apparatus according to the present invention that achieves the above object carries a toner image on an image carrier and transports the toner image to a predetermined transfer position.
The sheet is conveyed to the transfer position along a predetermined sheet conveyance path passing through the transfer position, the toner image is transferred to the sheet, and the sheet on which the toner image has been transferred is further conveyed to the toner image. In the image forming apparatus which forms an image composed of a fixed toner image on the sheet by discharging the sheet after fixing the sheet on the sheet, the image forming apparatus is located at the most downstream portion of the sheet transport path and carries the fixed toner image. A discharge roll that discharges the discharged paper, a driving source that generates a driving force transmitted to the discharge roll, and a driving force that transmits the driving force of the driving source to the discharge roll to rotate the discharge roll in the normal direction in which the paper is discharged. And a reversing transport unit for reloading and transporting the paper once discharged halfway by the forward rotation of the discharge roll by reversing the rotation of the discharge roll. The path is such that the transmission of the driving force of the driving source to the discharge roll can be stopped by mounting the reversing transport unit, and the reversing transport unit transfers the driving force of the driving source to the discharge roll so that the drive roller can rotate normally and reversely. It has a second drive path for transmission.

Here, in the image forming apparatus of the present invention, the first transport path is constituted by a gear train including a gear which is disengaged by mounting a reversing transport unit, and the second transport path. The path is preferably constituted by a gear train provided with a clutch mechanism for switching the driving force between forward rotation and reverse rotation.

In the image forming apparatus of the present invention, a double-sided printing unit for receiving a sheet taken in again by reverse rotation of a discharge roll from a reversing conveyance unit and conveying the sheet upside down to the transfer position again can be mounted. Preferably, it is Alternatively, the reverse transport unit itself may have the function of such a double-sided print unit.

Further, the image forming apparatus according to the present invention includes a plurality of image forming members on which a latent image is formed on a surface and the latent image is developed with toner of each color to carry a toner image on the surface. The image carrier may be an intermediate transfer body that circulates along the plurality of image forming bodies, receives a transfer of the toner image from the plurality of image forming bodies, and conveys the toner image to the transfer position. .

In the image forming apparatus of the present invention, when only the basic structure is provided, the discharge roller performs only forward rotation by transmitting a driving force through the first drive path, and when the reverse transport unit is mounted, the discharge roller is rotated in the first direction. The transmission of the driving force to the discharge roll by the first drive path is stopped, and the second transfer path on the reversing conveyance unit side is stopped.
The driving force is transmitted through the driving path of the first and second motors so that the motor can rotate normally and reversely.
Therefore, the basic configuration only needs to have a function of cutting off the first drive path when the reverse transport unit is mounted, and does not need to include a complicated mechanism such as a crack mechanism in the basic configuration. The first drive path in the inside and the second drive path in the reverse conveyance unit are adjusted.

[0014]

Embodiments of the present invention will be described below.

FIG. 1 is a diagram showing a configuration of an image forming apparatus as one embodiment of the present invention.

The image forming apparatus 100 shown in FIG.
Four drum-shaped image forming bodies 10 rotating in the direction of arrow A
a, 10b, 10c, and 10d. On these image forming bodies 10a, 10b, 10c, 10d, toner images of respective color toners are formed on their surfaces by an electrophotographic forming process. That is, the surfaces of the image carriers 10a, 10b, 10c and 10d are uniformly charged by the respective charging rolls 11a, 11b, 11c and 11d, and the laser light 12a, Irradiation of the electrostatic latent images 12b, 12c, and 12d forms respective electrostatic latent images.
a, 13b, 13c, and 13d developed by C, M,
A toner image is formed by each of the Y and K color toners, and the transfer rolls 14a, 14b, 14c, and 14d operate to form toner images.
Endless belt-shaped intermediate transfer body 1 circulating in the direction of arrow B
5 so as to be sequentially stacked.

Each of the developing units 13a, 13b, 13c, 1
3d, a toner tank 16 provided with each color toner is provided.
The toners of the respective colors are supplied from a, 16b, 16c and 16d.

The toner image transferred onto the intermediate transfer member 15 is conveyed to a transfer position T by the movement of the intermediate transfer member 15 in the direction of arrow B.

On the other hand, the paper P in the paper tray 20 or the paper P placed on the manual feed stand 21
The paper P is conveyed toward the transfer position T along the paper conveyance path R while being guided by the sheet P, and is synchronized with the timing at which the toner image on the intermediate transfer body 15 is conveyed to the transfer position T by the pair of registration rollers 23. Is adjusted to the transfer position T, and then transferred to the transfer position T.

The paper P conveyed to the transfer position T includes
While the paper P continues to be further transported, the transfer roll 3
By the operation of 1, the toner image on the intermediate transfer body 15 is transferred onto the paper P. Here, the transfer roll 31 has a function of cleaning the intermediate transfer body by attaching unnecessary toner on the intermediate transfer body 15 to itself (the transfer roll 31). The transfer roller 31 includes a cleaning blade 32 for removing toner adhered to itself (the transfer roll 31) from the transfer roll, and a waste toner tank for storing the removed waste toner. The transfer roller 31, the cleaning blade 32, and the waste toner tank 33 are further provided with one of the pair of registration rollers 23 (the driven side registration roller 23 a and the driving side registration roller 23 b).
a and a portion 22a of the guide member 22 in the vicinity of one of the registration rollers 23a is configured as an integrated transfer unit 30.

Paper P further transported through the transfer position
The toner image is fixed on the paper P by passing through a fixing device 40 having a pair of fixing rolls 41, further proceeds along the conveyance path R, and is sent out by the discharge roll 51 in the direction of arrow C, and It is discharged onto the discharge table 61. Here, the sheet transport path R of the discharge roll 51 is
The rotation in the direction in which the paper P conveyed along the paper is discharged to the paper discharge table 61 is referred to as “forward rotation”. The sheet P is discharged onto the sheet discharge table 61 with the surface on which the image is formed facing down.

The image forming apparatus 100 can optionally include a reverse transport unit 200 and a double-sided print unit 300. FIG. 1 shows a state in which both units are mounted.

The reversing and conveying unit 200 has a function of discharging the sheet P onto the sheet carry-out tray 62, and is also used when forming an image on both sides of the sheet P in cooperation with the duplex printing unit 300.

The paper P
When the paper is to be discharged onto the paper discharge tray 62, the gate 52 is switched after passing through the fixing roll 41, so that the discharge tray 6 is moved in the direction of arrow E along the paper transport path R '.
Send out on 2. By doing so, the paper discharge tray 62
The paper P is discharged with the surface on which the image is formed facing upward.

The paper P
Another method for discharging the paper onto the paper discharge tray 62 is as follows.
The paper P being sent out on the upper side 1 is again rotated by rotating the discharge roll 51 in the stage where the rear end portion of the paper P is still sandwiched between the discharge rolls 51 and feeding the paper P in the direction of the arrow D, so that the inside of the machine is The sheet P is sent along the sheet transport path R ′, and is sent out onto the sheet discharge tray 62 in the direction of arrow E. In this manner, the sheet P can be discharged to the sheet discharge tray 62 with the surface on which the image is formed facing downward, similarly to the case where the sheet is discharged onto the sheet discharge table 61.

When performing double-sided printing for forming an image on both sides of a sheet, the reverse transport unit 20 is used.
0 and both-side print unit 300 must be mounted. Here, the duplex printing unit 300
Is mounted in the direction of arrow G from the left in FIG. 1 so as to fit into the opening formed therein.

When performing double-sided printing using the screen forming apparatus 100 equipped with these two units 200 and 300, first, the sheet P on which an image is formed on the surface through the above-described process is placed at the rear end of the sheet. The sheet discharge table 6 is moved in the direction of arrow C until it is sandwiched between the discharge rollers 51.
1 and then the discharge roll 51 rotates in the reverse direction to convey the paper P in the direction of arrow D, and further guides the paper to the double-sided printing unit 300 by the action of the gate 53 to follow the reverse conveyance path R ″. To transport in the direction of arrow F,
Synchronized with the timing at which the toner image formed as an image on the back surface of the sheet is conveyed to the transfer position T by the registration roller 23, the conveyance is performed again to the transfer position T, and the toner image is formed on the back surface of the sheet. Is further transferred, and the toner image is fixed on the back side of the sheet by the fixing device 40, and the sheet formed from the image on both sides in this way is
The sheet is discharged onto a sheet discharge table 61 by a discharge roller 51. In this case, the paper discharge tray 62 may not be provided. Alternatively, the sheet on which the double-sided printing has been performed may be discharged onto the sheet discharge tray 62 in the same manner as described above with the sheet discharge tray 62 attached.

Here, the paper P being discharged for some reason is
In consideration of the case where the paper jams in the middle, a jam clear cover 400 that opens to the left (in the direction of arrow H) in FIG. 1 around the hinge 401 is provided, and the transfer unit 30 and the reverse transport unit 200 are provided. , And the double-sided print unit 300 are mounted on the jam clear cover 400. By opening the jam clear cover 400 in the direction of arrow H with the hinge 401 as the center, the paper jammed in the paper transport path R can be removed.

The double-sided printing unit 300 also has a cover 302 that opens outward (in the direction of arrow I) with the hinge 301 as the center. The paper can be removed.

FIG. 2 shows the image forming apparatus 100 shown in FIG.
Of the reverse transport unit 200 and the duplex printing unit 3
FIG. 4 is a diagram illustrating a drive mechanism (an example of a drive mechanism that constitutes a first drive path according to the present invention) provided in a portion other than 00 (hereinafter, referred to as a main body) and that drives the discharge roll 51.

Here, a lever 600 that is rotatable about a rotation shaft 601 is provided.
A gear mounting portion 602 to which the rotatable sheet No. 02 is rotatably mounted is provided, and a push portion 603 which is pushed in the direction of arrow K by the reverse transport unit 200 when the reverse transport unit 200 is mounted is provided at the other end. . The gear 502 attached to the lever 600 is rotated in the direction of arrow J by its own weight and the urging force of a spring (not shown).
1 and a gear 503 for transmitting the driving force of the motor 500 to the discharge roll 51 (see FIG. 1). In this case, the driving force from the motor 500 is transmitted to the main drive gear 501, transmitted to the gear 502 attached to the lever 600, further transmitted to another gear 503, and finally transmitted to the discharge roll 51. Then, the discharge roll 51 rotates in the forward direction.

Although not shown, the main drive gear 501 has a sheet transport path R other than a discharge roll.
Each of the upper drive rolls and image carriers 10a, 10b, 10c,
It also plays a role of transmitting the driving force to the intermediate transfer member 10 d and the intermediate transfer member 15.

Here, when the reverse transport unit 200 (see FIG. 1) is mounted on the main body, the pushing portion 603 of the lever 600
Is pushed in the direction of arrow K by the reverse transport unit 200, and as a result, the gear 502 moves in the direction L,
02 is disengaged from the main drive gear 501. At the same time, the driving force is transmitted to the reverse conveyance unit via the gear 504 meshed with the main drive gear 501, and the driving force returned from the reverse conveyance unit is transmitted to the gear 505 meshed with the gear 503. Then, the driving force is transmitted to the gear 503 and transmitted to the discharge roll.

FIG. 3 is a diagram showing a drive mechanism (an example of a drive mechanism constituting the second drive path according to the present invention) provided in the reverse transport unit.

Here, two clutches 520, 530
Is provided. These two clutches 520, 53
0 of the clutch 520 is connected to a discharge roll (FIG. 1).
When the discharge roll 51 is rotated reversely (when the primary gear 521 and the secondary gear 522 provided coaxially are connected to each other and rotate integrally) when the discharge roll 51 is rotated forward. Is turned off (a state in which the two gears 521 and 522 freely rotate with respect to each other), and the other clutch 530 is turned on (the primary side The gear 531 and the secondary gear 532 are connected and rotate integrally with each other, and are turned off (the two gears 531 and 532 rotate freely with each other) when the discharge roll 51 is rotated forward. Is controlled as follows. The clutch 530
Gear 533 is one of the primary gears that always rotates integrally with the gear 531.

The driving force transmitted from the gear 504 (see FIG. 2) is transmitted in the order of the gear 506, the gear 507, and the gear 508. When rotating the discharge roll in the forward direction,
Since the clutch 520 is on and the clutch 530 is off, it is transmitted from the gear 508 to the primary gear 521 of the clutch 520, and transmitted from the secondary gear 522 to the gear 50.
9 and further transmitted to the gears 510 and 511 sequentially to the gear 505, and then transmitted to the discharge roll via the above-described path to rotate the discharge roll in the forward direction.

Here, the gear 5 on the secondary side of the clutch 530
32 meshes with the secondary gear 522 of the clutch 520, so that the driving force transmitted from the gear 508 to the primary gear 521 of the clutch 520 is transmitted to the clutch 530 via the secondary gear 522. Secondary gear 53
2, the clutch 530 is in the off state at the timing of rotating the discharge roll forward, so that the primary gear 531 and the secondary gear 532 can rotate freely with respect to each other. 530
The gear 532 on the secondary side is only idling and has no adverse effect. Gear 508 to clutch 5
The driving force transmitted to the primary side gear 531 is
The light is transmitted to the gear 512 via the gear 533 on the primary side of the sheet, and further transmitted to a drive roll (not shown) constituting a transport path in the reverse transport unit.

On the other hand, when the discharge roll is rotated in the reverse direction,
The clutch 520 is controlled to be off and the clutch 530 is controlled to be on. The driving force transmitted in the order of the gears 506, 507, and 508 is transmitted to the primary gear 531 of the clutch 530.
To the secondary gear 522 of the clutch 520 via a secondary gear 532 that rotates integrally with the primary gear 531, and further to the gears 509, 510,
511 is communicated. At this time, the driving force is also transmitted from the gear 508 to the primary gear 521 of the clutch 520, but the clutch 520 is controlled to be off, and thus the primary gear 521 and the secondary gear 521 of the clutch 520 are turned off. The gears 522 can rotate freely with each other, and the gear 521 on the primary side of the clutch 520 only idles without any particular adverse effect.

The driving force transmitted from the gear 508 to the primary gear 531 of the clutch 530 is transmitted to the gear 512 via the gear 533, which is also the primary gear, and transmitted to the transport path in the reverse transport unit. Driving force is transmitted.

Here, the gear 532 on the secondary side of the clutch 530 that performs reverse rotation of the discharge roll is a gear having a large diameter. That is, when the discharge roll 51 is rotated in the reverse direction (when the paper is drawn into the machine again), compared with when the discharge roll is rotated forward (when the paper is sent out onto the paper discharge table 61 (see FIG. 1)). This means that the discharge roll 51 is rotated at a high speed and the paper is drawn at a high speed.
This is because, in the image forming apparatus 100 shown in FIG. 1, when images are sequentially formed on each of the sheets while sequentially transferring the plurality of sheets P, the sheet is conveyed next without rotating in reverse at a high speed. This is because it interferes with the paper.

Although the detailed description is omitted, in this embodiment,
A unique driving source is provided in the double-sided printing unit 300, and at the timing when one sheet is conveyed over both the reverse conveyance unit 200 and the double-sided printing unit 300, the sheet conveyance in the double-sided printing unit 300 is performed. The speed is equal to the transport speed of the reverse transport unit 200 (the paper transport speed when the discharge roll 51 is rotated in the reverse direction), and one sheet of the sheet is
The transport speed is switched between two stages so that the transport speed coincides with the same transport speed as the paper transport speed in the paper transport path R after leaving from zero.

In the present embodiment, as described above, the drive mechanism of the main body only rotates the discharge roll in the forward direction, and the drive mechanism of the main body is provided with the lever 600 when the reverse transport unit is mounted. The driving force transmission path is cut off, and a mechanism for switching the driving force of the motor 500 between the forward and reverse directions and transmitting the driving force to the discharge rolls is provided in the reversing conveyance unit. The rotation of the discharge roll can be appropriately controlled without imposing a great burden on a user.

[0043]

As described above, according to the present invention,
Adjustment of a drive mechanism for rotating the discharge roll forward in the basic configuration only and a mechanism for driving the discharge roll in a forward and reverse rotation when the optional mechanism is attached are achieved.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of an image forming apparatus as one embodiment of the present invention.

2 is provided in a main body of the image forming apparatus shown in FIG.
FIG. 4 is a diagram illustrating a driving mechanism that drives a discharge roll.

FIG. 3 is a diagram illustrating a drive mechanism configured in the reverse transport unit.

[Explanation of symbols]

10a, 10b, 10c, 10d Image forming body 11a, 11b, 11c, 11d Charging roll 12a, 12b, 12c, 12d Laser light 13a, 13b, 13c, 13d Developing device 14a, 14b, 14c, 14d Transfer roll 15 Intermediate transfer body 16a, 16b, 16c, 16d Toner tank 20 Paper tray 21 Bypass stand 22 Guide member 22a Portion of guide member near registration roll 23 Registration roll 23a, 23b Registration roll 30 Unit 31 Transfer roll 32 Cleaner 33 Waste toner tank 40 Fixing device 41 Fixing roll 51 Discharge roll 61 Paper discharge stand 100 Image forming apparatus 200 Reverse transport unit 300 Double-sided print unit 301 Hinge 302 Cover 400 Jam clear cover 401 Hinge 500 Motor 501 Main drive A 502,503,504,505,506,507,5
08, 509, 510, 511, 512 Gear 520 Clutch 521 Primary gear 522 Secondary gear 530 Clutch 531 Primary gear 532 Secondary gear 533 Primary gear

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H028 BA06 BA09 BB02 3F053 BA03 BA14 BA19 LA03 LA07 LB03 3F100 AA02 BA23 BA27 CA07 CA12 CA13 CA15 EA02 EA05 EA06 EA13 3J062 AA35 AB01 AC04 BA12 CG75

Claims (4)

[Claims] 1. A toner image is carried on an image carrier, the toner image is transported to a predetermined transfer position, and a sheet is transported to the transfer position along a predetermined paper transport path passing through the transfer position. Then, the toner image is transferred to the sheet, the sheet on which the toner image has been transferred is further transported, and the toner image is fixed on the sheet, and then the sheet is discharged.
An image forming apparatus for forming an image comprising a fixed toner image on the sheet, a discharge roller positioned at the most downstream portion of the sheet transport path and discharging a sheet carrying the fixed toner image, and transmitting the sheet to the discharge roller. A driving source that generates a driving force to be transmitted, and a first driving path that transmits the driving force of the driving source to the discharge roll and causes the discharge roll to rotate forward in a direction in which paper is discharged. A reversal transport unit that re-takes and conveys the sheet once discharged halfway by the forward rotation of the discharge roll by reversing the rotation of the discharge roll is freely attachable, and the first drive path is configured by mounting the reverse transport unit. Transmission of the driving force of the drive source to the discharge roll is stopped, and the reversing transport unit transfers the drive force of the drive source to the discharge roll in a forward direction. An image forming apparatus characterized in that having a second drive path which rolling freely transmitted. 2. The first conveyance path includes a gear train that includes a gear that is disengaged by mounting the reverse conveyance unit, and the second conveyance path has a driving force of a normal rotation. 2. The image forming apparatus according to claim 1, further comprising a gear train including a clutch mechanism for switching between a reverse rotation and a reverse rotation. 3. A double-sided printing unit, which receives a sheet retaken by the reverse rotation of the discharge roll from the reversing conveyance unit and conveys the sheet upside down to the transfer position again, is attachable. The image forming apparatus according to claim 1. 4. A plurality of image forming bodies each having a latent image formed on a surface thereof and developed with each color toner and carrying each toner image on the surface, wherein the image bearing body includes the plurality of image forming bodies. 2. The image forming apparatus according to claim 1, wherein the image forming apparatus is an intermediate transfer member that circulates along the image forming member, receives a transfer of the toner image from the plurality of image forming members, and transports the toner image to the transfer position.