JPH09272648A - Paper sheet reverse device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify a constitution and prevent an impulse sound from generated by rotatingly driving a second roll carrier means and releasing a press contact state of either of a first or a second roll means which pressedly contact with the second roll carrier means. SOLUTION: A triroll 19 constituting a part of a reverse device 14 is arranged between a feeding path 17 and a delivery path 18 of a paper sheet reverse device 14. In this triroll 19, a drive roll 19B and a first and a second driven rolls 19A, 19C are arranged in a pressedly contact state so that a nip part between the first driven roll 19A and the drive roll 19B is positioned in the feeding path 17 and a nip part between the drive roll 19B and the second driven roll 19C is positioned in the delivery path 18. When a solenoid is turned on, the second driven roll 19C is pressedly in contact with the drive roll 19B, and in the case of being turned off, the press contact state of the drive roll 19B is released. A reverse path 25 is linked to the bottom end of a converging part of the feeding and delivery paths 17, 18, and a lead-in part and a double- face/multiple record path 26 is formed in the bottom end of the reverse path 25.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet reversing device used in an image forming apparatus such as an electrophotographic copying machine and a printer, and more particularly to a sheet used when the sheet is conveyed in the reverse direction or the front and back sides. The present invention relates to a reversing device.

[0002]

2. Description of the Related Art Recently, in an image forming apparatus such as an electrophotographic copying machine or a printer, or a copying machine / printer complex machine, an ADF (Auto Document) is used.
Since it is necessary to correctly eject a plurality of sheets of paper on which a series of original images continuously read by a feeder or a series of images sent from a host computer or the like are formed in page order, A paper reversing device is arranged between the image forming portion and the discharge portion so that the orientation of the image surface when the paper is discharged can be selected, and it has already been proposed and is being commercialized. However, in the above-mentioned sheet reversing device, there is a difference in copy / print productivity between when the sheet is discharged as it is and when the sheet is reversed and discharged, which is a problem in controlling the image forming apparatus. Occurs. Therefore, 2 for 1-axis drive roll
By providing a so-called "triroll", which has two nip lines that pinch the paper by pinching the pinch rolls of the shaft, in the vicinity of the reversing point that changes the conveying direction of the paper, Since the sheets can be sandwiched at short time intervals, the interval between sheets can be shortened, and it becomes easy to secure the required productivity.

As a sheet reversing device used in such an image forming apparatus, for example, there is a triroll type device disclosed in Japanese Utility Model Publication No. 1-41717. The sheet-like conveyed product reversing device according to Japanese Utility Model Publication No. 1-41717 has a drive motor 10 as shown in FIGS. 14 and 15.
Two driven rolls 104 and 105 are brought into pressure contact with one drive roll 103 which is rotationally driven by 0 via the drive gear 101 and the driven gear 102. This triroll type sheet conveyor reversing device
The paper 106 having an image formed on one side is conveyed by one driven roll 104, the drive roll 103 and a roll (not shown), and then is conveyed by reversing the conveyance direction by the other driven roll 105 and the drive roll 103. ing.

[0004]

However, the prior art described above has the following problems. That is, in the case of the paper reversing device of the image forming apparatus, the speed at which the paper is fed into the paper reversing roll depends on the process speed (image forming speed) of the image forming unit, whereas After flipping, there are few such restrictions. Therefore, by setting the conveying speed after reversing the paper to a speed faster than the process speed and sending the paper at a high speed, it is possible to improve productivity and secure the necessary processing time in post-processing devices such as sorters. Conceivable.

However, in the case of the sheet-like conveyed product reversing device according to Japanese Utility Model Publication No. 1-41717, as shown in FIGS. 14 and 15, the drive motor 100 causes the drive gear 101 and the driven gear 102 to intervene. 1 driven to rotate
Two driven rolls 104, 1
No. 05 is press-contacted, the speed of the drive motor 100 can be changed before and after the reversal of the sheet by changing the speed change means of the drive motor 100 or the clutch and the speed change gear. Therefore, there is a problem in that a means is required, an increase in cost is caused, and an impulse sound is generated due to a change in the rotation speed of the drive motor or the like when the speed is changed, which causes a tactile noise in an office environment.

Further, in the case of the sheet-like conveyed product reversing device according to the above Japanese Utility Model Publication No. 1-41717, as shown in FIGS. 14 and 15, one driving roll 103 and two driven rolls 104, Since 105 is in pressure contact with each other, if the paper on the sending side and the paper on the sending side are simultaneously sandwiched by the two nip lines, it is necessary to convey the respective papers at the same speed, which further improves the productivity. There is also a problem in that it is impossible to control the speed of the paper on the sending side in order to increase the speed.

Further, in the case of the sheet-like conveyed product reversing device according to the above-mentioned Japanese Utility Model Publication No. 1-41717, in addition to discharging the reversed paper, the reversed paper is returned to the inside of the image forming apparatus and placed on the back surface. When a triroll is used as the sheet reversing device of such an image forming apparatus, the pinch roll on the sending side needs to be operating in the mode of forming an image on the back side. There is no.
However, when the trirole according to the above proposal is used,
Since it is not possible to stop only the pinch roll on the sending side, the pinch roll on the sending side unnecessarily rotates, which causes a problem that unnecessary load and noise are generated.

Further, the sheet reversing device used in the image forming apparatus is arranged at a position immediately after the image is formed on one side of the sheet in the image forming section, but the image is formed on one side in the image forming section. Since the heat received in the immediately preceding fixing step remains on the formed sheet 106, the sheet 10 is removed.
The toner fixed on 6 is in an unstable state.
By the way, as shown in FIGS. 15 and 16, the sheet-shaped conveyed product reversing device according to the above Japanese Utility Model Publication No. 1-41717 has the drive roll 1 on the surface of the paper 106 on which the toner is placed.
03 is in contact with the sheet 106, and the driving roll 103 is usually made of a material that is easily elastically deformed (having a small Young's modulus). Therefore, the sheet 106 immediately after fixing is driven by the driving roll 103 and the driven roll 104. When the sheet is nipped and conveyed by the drive roll 103
Remarkably elastic deformation occurs in the nip between the driving roll 103 and the driven roll 104, and the driving roll 103 and the paper 1
There is a problem in that the relative speed with respect to 06 changes, toner peeling easily occurs, and the image quality deteriorates.

To further explain, in the case of the above-mentioned sheet reversing device, the same sheet 103 is provided in plural pairs of rolls 103, 1
The rolls 103, 10 are sandwiched between 04 and 105 for conveyance.
The rolls 103, 104 due to the difference in the degree of wear of Nos. 4 and 105, the difference in the pressure applied, or the variation in the material,
Due to the relative speed difference between the rolls 105, the rolls 103, 10
A sliding force is generated in the shearing direction between the surfaces of the sheets 4, 105 and the paper 106. At this time, when the toner surface is nipped and conveyed while being in contact with the driving roll 103, the driving roll 103
Does not rotate in order to absorb the sliding force, so a slip occurs between the drive roll 103 and the paper 106, and unstable toner peels off due to residual heat.

Such a problem is not limited to the electrophotographic image forming apparatus, and similarly when the image surface formed by another method such as an ink jet recording method is conveyed while being in contact with the driving roll. appear.

As described above, when the image-forming surface of the sheet comes into contact with the driving roll and the image-forming material such as the toner is peeled off, the portion where the toner or the like is peeled off on the sheet is called a blank area. In addition, there is a problem in that the peeled toner or the like adheres to a portion where the toner originally does not adhere and stains the image forming surface.

In the construction of a normal copying machine, since an image is copied on the upper surface of the paper and then the paper is conveyed downward by a triroll, the image forming surface comes into contact with the drive roll side immediately after image formation and before reversal. Since the sheet is nipped and conveyed, the image forming surface is significantly soiled.

Therefore, the present invention has been made in order to solve the above-mentioned problems of the prior art, and its object is to change the conveying speed of the sheet before and after the sheet is reversed. Even when configured, the configuration is simple, it is possible to prevent cost increase, or to prevent the generation of impulse sound, and even when the paper is pinched at the sending side and the sending side at the same time, It is an object of the present invention to provide a sheet reversing device capable of increasing the speed of the sheet on the delivery side, avoiding unnecessary roll rotation, and producing low noise and preventing the image forming surface from being contaminated.

[0014]

That is, the sheet reversing device according to claim 1 of the present invention comprises first, second and third roll conveying means constituted by attaching a roll member to a shaft-like member. The first roll transporting means and the second roll transporting means are brought into pressure contact with each other, the second roll transporting means and the third roll transporting means are brought into pressure contact with each other, and the first roll transporting means and the second roll transporting means are provided. The sheet conveyance direction at the pressure contact portion with the roll conveyance means and the sheet conveyance direction at the pressure contact portion between the second roll conveyance means and the third roll conveyance means are set substantially opposite to each other, and the sheet conveyance is performed. In a sheet reversing device capable of transporting in a state in which the direction is reversed, the second roll transporting unit is rotationally driven, and either the first roll transporting unit or the second roll transporting unit is brought into pressure contact with the second roll transporting unit. To cancel It is obtained by configured to provide removal means.

The sheet reversing device according to a second aspect of the present invention is provided with first, second and third roll conveying means constituted by attaching a roll member to a shaft-shaped member, and the first roll. The transport means and the second roll transport means are in pressure contact with each other, and the second roll transport means and the third roll transport means are in pressure contact with each other, so that the first roll transport means and the second roll transport means are in contact with each other.
The sheet conveyance direction at the pressure contact portion with the roll conveyance means and the sheet conveyance direction at the pressure contact portion between the second roll conveyance means and the third roll conveyance means are set substantially opposite to each other, and the sheet conveyance is performed. In a paper reversing device that can be conveyed with its direction reversed, two roll conveying means of the first, second and third roll conveying means can be independently driven and are rotationally driven. A roll transporting unit that is configured by a roll-shaped member that is rotatably attached to a shaft-shaped member as a roll member of another roll unit that comes into pressure contact with a roll member that is rotationally driven Is configured so as to be set to be faster than the transport speed of the roll transport means located on the paper feeding side.

Therefore, in the paper reversing device according to the first aspect of the present invention, when the second roll conveying means is driven to rotate, the first or second roll is brought into pressure contact with the second roll conveying means. Since the releasing means for releasing any pressure contact state of the conveying means is provided, when the sheet is nipped and conveyed by another conveying means,
The first means that is brought into pressure contact with the second roll conveying means by the releasing means
Alternatively, by releasing any pressure contact state of the second roll transport means, it is possible to change the transport speed of the sheet between the input side and the output side with a simple configuration and low cost, and an impulse sound is generated. Can be prevented from occurring,
Moreover, even when the paper is sandwiched between the sending side and the sending side at the same time, the speed of the paper on the sending side can be increased, and unnecessary rotation of the roll can be avoided to reduce the noise and reduce the noise on the image forming surface. It is possible to provide a sheet reversing device that can prevent stains from occurring.

Further, in the sheet reversing device according to the second aspect of the present invention, the two roll conveying means among the first, second and third roll conveying means can be independently driven, and The roll member of the other roll means that comes into pressure contact with the rotation driven roll member of the rotation driven roll transport means is constituted by a roll-shaped member rotatably attached to a shaft-shaped member, and is provided on the sheet delivery side. Since the transport speed of the roll transport unit located is set to be higher than the transport speed of the roll transport unit located on the paper feeding side, the transport speed of the sheet can be reduced with a simple configuration and low cost. It is possible to change between the sending side and the sending side, it is possible to prevent the generation of impulse sound,
Moreover, even when the paper is sandwiched between the sending side and the sending side at the same time, the speed of the paper on the sending side can be increased, and unnecessary rotation of the roll can be avoided to reduce the noise and reduce the noise on the image forming surface. It is possible to provide a sheet reversing device that can prevent stains from occurring.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION

First Embodiment Hereinafter, the present invention will be described based on the illustrated embodiments.

FIG. 2 shows an image forming apparatus to which the sheet reversing device according to the embodiment of the present invention is applied.

In the figure, 1 is an ADF (Auto Document Feeder) for an image of an original document not shown.
It indicates an image input unit to be read using or a series of image information is input from a host computer or the like,
From the image input unit 1, image information is output to the laser scanning unit 2. The laser scanning unit 2 irradiates the photosensitive drum 3 previously uniformly charged by the primary charger 4 with laser light based on image information at two exposure positions in accordance with an image forming mode, based on image information. This forms an electrostatic latent image. The electrostatic latent image formed on the photosensitive drum 3 is developed by a developing device 5 and / or a developing device 6 with toners of different colors as necessary. Further, the toner image developed on the photosensitive drum 3 is supplied from a paper storage unit 9 of a paper supply unit 10 and transferred onto a recording paper S fed at a predetermined timing by a registration roll 11 onto a transfer roll 7. Is transcribed. The recording sheet S to which the toner image has been transferred is conveyed to the fixing device 13 by the conveying belt 12, and the toner image is fixed on the recording sheet S by the fixing device 13 by heat and pressure. The recording paper S on which the toner image is fixed passes through the discharge passage 16 and is directly discharged to the outside of the apparatus by the discharge roll 15 or the paper reversing device 14 or the feeding passage 17 or the feeding passage 18 depending on the image forming mode. If necessary, the sheet is discharged from the discharge roll 15 to the outside of the apparatus in a state where the conveying direction and the front and back are reversed, and again to the image forming portion of the photosensitive drum 3 via the double-sided / multiplex recording passage 26. It is transported and double-sided or multi-recorded.

The cleaning device 8 removes residual toner from the surface of the photosensitive drum 3 after the image forming process is completed, so that it is ready for the next image forming process.

1 and 3 show a sheet reversing device used in the image forming apparatus having the above-mentioned structure.

In FIG. 3, reference numeral 14 denotes a sheet reversing device provided in the discharge section of the image forming apparatus. Between the exit roll 13a of the fixing device 13 of the image forming apparatus and the discharge roll 15, The discharge passage 16 is formed in a straight line obliquely upward, and below the discharge passage 16, a feed passage 17 extending obliquely downward from the upstream side of the discharge passage 16 in the conveyance direction of the recording sheet S. And the delivery passage 18 extending obliquely downward from the downstream side of the discharge passage 16 in the transport direction of the recording paper S are arranged so as to form a substantially triangular shape. A switching member 27 for switching the recording sheet S discharged from the fixing unit 13 between the discharge passage 16 and the feed passage 17 is provided at the entrance of the discharge passage 16 and the feed passage 17.
Is tiltably arranged by a solenoid (not shown).

By the way, the sheet reversing device 1 is provided between the feeding passage 17 and the sending passage 18 of the sheet reversing device 14.
A triroll 19 which constitutes a part of No. 4 is arranged.
In the triroll 19, the nip portion between the first driven roll 19A and the driving roll 19B is located in the feed passage 17, and the nip portion between the driving roll 19B and the second driven roll 19C is located in the delivery passage 18. In addition, the drive roll 19B and the first and second driven rolls 19A and 19C are arranged in pressure contact with each other.

As shown in FIG. 1, the triroll 19 has a drive roll 19B located between the feed passage 17 and the feed passage 18 from three roll members 41, 42, 43 fixed to a drive shaft 40. This drive roll 19 is constructed
The B drive shaft 40 is rotationally driven by a drive motor 44, a drive gear 45, and a driven gear 46. Further, the first driven roll 19A located in the feed passage 17 is rotatably attached to the fixed shaft 48, and is driven by rollers 94, 5 which come into pressure contact with the roll members 41, 42, 43 of the drive roll 19B.
The fixed shaft 48 of the first driven roll 19A is fixed to the frame 52 of the image forming apparatus. Further, the second driven roll 19C located in the delivery passage 18 is rotatably attached to the fixed shaft 53, and the roll members 41, 42 of the drive roll 19B,
43 and driven rollers 54, 55, 56 which are in pressure contact with each other, and a fixed shaft 53 of the second driven roll 19C.
Is an elongated hole 57 formed in the frame 52 of the image forming apparatus.
In addition, it is movably supported in a direction in which it comes in contact with and separates from the drive roll 19B. Further, a solenoid 59 is connected to the fixed shaft 53 of the second driven roll 19C via a link 58 at an end portion protruding to the outside of the frame 52 of the image forming apparatus. The fixed shaft 53 of the roll 19C is urged by a spring 60 so that the driven rollers 54, 55, 56 are in pressure contact with the roll members 41, 42, 43 of the drive roll 19B. Then, the second driven roll 19C has a solenoid 59
By turning on, the driven rollers 54, 5
5, 56 are roll members 41, 42 of the drive roll 19B,
By making pressure contact with 43 and turning off the solenoid 59, the driven rollers 54, 55, 56 and the drive roll 19
The pressure contact state with the B roll members 41, 42 and 43 is released. As shown in FIG. 3, the solenoid 59 is provided with a spring 61 that releases the pressed state between the driven rollers 54, 55, 56 and the roll members 41, 42, 43 of the drive roll 19B.

Further, the inlet passage 17 and the outlet passage 18 are provided.
As shown in FIG. 3, a reversing passage 25 is connected to the lower end of the merging portion located at the lower end of the reversing passage 25 in an inclined state. 25A and a double-sided / multiple-recording path 26 are formed so as to be branched. A switching member 20 for switching the conveyance direction of the recording sheet S is arranged at a branch portion between the pull-in portion 25A and the double-sided / multiple recording path 26, and a PET film or the like is provided at a lower end portion of the switching member 20. A shield plate 31 composed of is formed so as to project downward. In the normal state, the shield plate 31 is provided with a retractable portion 25 as shown in the figure.
The switching member 20 is arranged so as to communicate with the double-sided / multiplex recording path 26 from A. A forward / reverse roll 21 and a pinch roll 22 for transporting the recording paper S are disposed above the pull-in portion 25A so that they can be pressed against each other. The pinch roll 22 can be released from the pressure contact state with the forward / reverse roll 21 by a solenoid 24 via a link 23.

In FIG. 3, reference numeral 23A denotes a fulcrum of the link 23, 24A denotes an operating rod of the solenoid 24, and 29 denotes a detection portion of a detection sensor 28 for detecting the leading edge and the trailing edge of the recording sheet S, respectively. There is.

With the above-described structure, the sheet reversing device of the image forming apparatus having the above-described structure is as follows.
Even when the sheet conveying speed is changed before and after the sheet is inverted, the configuration is simple, and it is possible to prevent cost increase and prevent the generation of impulse noise. Even when the paper is sandwiched between the sending side and the sending side at the same time, the speed of the paper on the sending side can be increased, and unnecessary rotation of the roll can be avoided to reduce noise.

That is, in the image forming apparatus, as shown in FIG. 2, an image of an original document (not shown) is converted by an image input unit 1 into an ADF (Auto Document Feed).
When read using r) or a series of image information is input from a host computer or the like, a toner image is formed on the photosensitive drum 3 based on the image information output from the image input unit 1. The toner image formed on the photoconductor drum 3 is fed from the sheet storage section 9 of the sheet feeding unit 10 and transferred by the transfer roll 7 onto the recording sheet S which is conveyed by the registration roll 11 at a predetermined timing. It The recording sheet S on which the toner image is transferred is fixed to the fixing device 1
3 fixes the toner image with heat and pressure.

In the single-sided copy normal discharge mode in the image forming apparatus, as shown in FIG. 1, the drive motor 44 of the triroll 19 of the sheet reversing device 14 is stopped, and as shown in FIG. The image forming operation is started in a state where the switching member 27 disposed at the entrance of the passage 16 is lowered downward, and the recording sheet S fixed by the fixing device 13 is transferred through the discharge passage 16 to the switching member. It passes above 27 and is discharged to the outside of the apparatus by the discharge roll 15 as it is. At that time, the exit roll 13 of the fixing device 13
After the trailing edge of the recording sheet S has passed through a, the discharge roll 15 is sped up to slightly increase FCOT (Fir).
st Copy Output Time: the time until the first copy is ejected can be shortened.
In this case, by detecting the leading edge of the recording sheet S with the detection sensor 28, it is detected that the trailing edge of the recording sheet S has fallen out of the exit roll 13a of the fixing device 13.

In the single-sided copy reversal discharge mode of the image forming apparatus, as shown in FIG. 1, the drive motor 44 of the triroll 19 of the paper reversing device 14 is driven and the drive roll 19B of the triroll 19 is rotationally driven. . As shown in FIG. 3, the switching member 27 disposed in the discharge passage 16 is lifted upward by a solenoid (not shown), and is switched from the discharge passage 16 to the inlet passage 17. Then, in this state, the image forming operation is started, and the recording paper S fixed by the fixing device 13 is transferred to the switching member 27.
The transporting direction is switched by and is transported to the feeding passage 17, and as shown in FIG. 1, it is fixed only in the thrust direction with respect to the fixed shaft 48 of the first driven roll 19A located in the feeding passage 17. Rotatable driven rollers 49, 5
0, 51 and the roll members 41, 42, 43 fixed to the drive shaft 40 of the drive roll 19B are guided to the nip portion, and by the drive force of the drive roll 19B, as shown in FIG. It is guided to the forward / reverse rotation roll 22 in the forward rotation state via the passage 25. As a result, the recording paper S is once guided into the pull-in path 25A by the forward / reverse roll 22 in the normal rotation state, but the upper end of the recording paper S has the switching member 2 at its upper end.
It is located above the lower end of the zero shield plate 31.

The recording paper S, which is once guided into the pull-in path 25A by the forward / reverse roll 22, has its upper end located above the lower end of the shield plate 31 of the switching member 20. It is conveyed to the reversal passage 25 again by reversing 22. The recording sheet S, with the surface on which the toner image is formed facing downward,
It is guided to the nip portion composed of the drive roll 19B and the second driven roll 19C arranged in the delivery passage 18 via the reversing passage 25, and is conveyed to the discharge roll 15 by the conveying force of the drive roll 19B. As a result, the recording paper S is ejected outside the apparatus by the ejection roll 15 with the surface on which the toner image is formed facing downward.

At this time, the second driven roll 19C of the triroll 19 sets the solenoid 59 to the ON state immediately before or immediately after the tip position of the recording sheet S reaches the delivery side of the triroll 19 after reversing. The recording paper S is nipped by the drive roll 19B, and the leading edge of the recording paper S is conveyed to the discharge roll 15. Then, the second driven roll 19C of the triroll 19 releases the nip with the drive roll 19B by turning off the solenoid 59 immediately after the leading end of the recording sheet S reaches the discharge roll 15, thereby performing recording. The sheet S is conveyed only by the conveying force of the discharge roll 15. As a result, immediately after the nip between the second driven roll 19C and the drive roll 19B is released, the discharge roll 15 is accelerated to increase the FC
OT (First Copy Output Tim)
e: The time until the first copy is discharged) can be shortened, and the productivity of the image forming apparatus can be improved.

If the recording sheet S on the feeding side and the recording sheet S on the feeding side are simultaneously sandwiched by the two nip lines on the feeding side and the feeding side of the triroll 19, the second driven roll 1
By releasing the nip between 9C and the drive roll 19B, the recording paper S on the sending side can be accelerated and conveyed by the discharge roll 15 that has been accelerated.

Further, in the double-sided copy mode of the image forming apparatus, as shown in FIG. 1, the drive motor 44 of the triroll 19 of the paper reversing device 14 is driven, the drive roll 19B of the triroll 19 is driven, and the solenoid is operated. 69 is turned off. The switching member 27 disposed in the discharge passage 16 is pulled upward by a solenoid (not shown) as shown in FIG.
The side is switched to the side of the feeding passage 17. The operation until the roll is guided to the forward / reverse roll 22 in the forward rotation state is the same as that in the single-sided copy reverse discharge mode. When the reversal timing of the recording paper S is delayed from the one-sided copy reversal discharge mode, the upper end of the recording paper S is at the lower end of the switching member 20 disposed at the branch between the reversing path 25 and the duplex / multiplex recording path 26. The switching member 20 is switched to the double-sided / multiplex recording path 26 by its own weight. Therefore, the recording paper S that is conveyed again by reversing the forward / reverse roll 22 is conveyed through the switching member 20 to the double-sided / multiple recording passage 26 with the surface on which the toner image is formed facing up. It The recording sheet S is again conveyed to the image forming section via the double-sided / multi-recording path 26 formed so as to be bent and folded, with the toner image formed side down, and the recording sheet S A toner image is formed on the back surface of the. The subsequent operation is the same as in the single-sided copy normal discharge mode. After the recording paper S having the toner images formed on both sides passes through the fixing device 13, the recording paper S is discharged outside the apparatus by the discharge roll 15 through the discharge passage 16. Is discharged. Therefore, in this double-sided copy mode, the solenoid 59 is turned off, and the driven roll 1 on the sending side is turned on.
Since it is not necessary to always release the nip between 9C and the drive roll 19B and to rotate the driven roll 19C, the load and noise can be reduced accordingly.

If necessary, in the case of the single-sided multiple recording mode, the recording sheet S having a toner image formed on one side is used.
However, the surface on which the toner image is formed is transferred to the photosensitive drum 3 via the reversing passage 25 and the duplex / multiplex recording passage 26 without being conveyed to the retracting portion 25A of the reversing passage 25 by switching of the switching member 20. Is conveyed again to the image forming section so that the toner image on the surface of the recording paper S is multiplex-transferred and discharged in the same manner as in the single-sided copy normal discharge mode.

Second Embodiment The second embodiment is applied to a case in which a discharge device of an image forming apparatus is combined with a post-processing device for performing punching processing and stapling processing. In such an image forming apparatus, when the speed is increased and discharged in the single-sided copy reversal discharge mode, as shown in FIG. 4, the distance between the sheet edges between the recording sheets and the time should be made larger than in the case where the speed is not increased. Therefore, it is possible to give a margin to time such as punching operation.

Further, when a post-processing device for performing stapling processing is combined with the discharge section of the image forming apparatus, a post-processing time is required between recording sheets of each predetermined number of sheets for performing stapling processing. Become. So, for example,
When the stapling process is performed for every three recording sheets, the stapling is performed between the ejection of the third recording sheet of the first set and the ejection of the first recording sheet of the second set. It is necessary to secure the time required for the ring processing. Therefore, according to the second embodiment, by accelerating and ejecting the final recording sheet in each unit, decelerating the first sheet in each unit, or ejecting after waiting for a certain time, or both. The time required for post-treatment can be secured.

Third Embodiment FIGS. 5 and 6 show a third embodiment of the present invention. In this third embodiment, a forward / reverse roll or the like is used to invert the recording paper in the inversion path. not,
It is configured to use other mechanisms. That is, in the third embodiment, as shown in FIG.
To reverse the recording paper S at
A pull-in portion 25A provided with a spring 60 is provided below the spring. The spring 60 elastically deforms by the conveying force of the recording sheet S, and the restoring force of the spring 60 causes the recording sheet S to be sent to the triroll 19 again. Is configured.

Further, in the case of the apparatus shown in FIG. 6, the recording paper S is sent to the pull-in portion 25A arranged vertically upward by the conveying force of the triroll 19, and the recording paper S is brought by its own weight. Is again conveyed to the delivery side of the triroll 19.

In order to switch between the sending side and the sending side,
As in the first embodiment, the switching member not shown is used.

The other structure and operation are the same as those in the above-mentioned embodiment, and the explanation thereof will be omitted.

Fourth Embodiment FIG. 7 shows a fourth embodiment of the present invention. In the fourth embodiment, the nip of only the driven roll 19A on the feed side of the triroll 19 can be released. . Also,
The delivery side of the triroll 19 is configured so as to also have a function as the discharge roll 15.
5 is not provided. As a result, in the single-sided copy reverse discharge mode of the image forming apparatus, the sending side of the triroll 19 functions as the discharge roll 15.

That is, in the fourth embodiment, the first driven roll 19A is arranged so that the nip can be released from the drive roll 19B. The first driven roll 19A
As shown in FIG. 7, a solenoid 71 is connected to an outer end of the fixed shaft 48 of the image forming apparatus, which is protruded to the outside of the frame 52, through a link 70, and the first driven roll 19A. The fixed shaft 48 of the driven shaft 49 is driven by rollers (not shown) at its middle portion.
Is urged so as to come into pressure contact with the roll members 41, 42, 43 of the drive roll 19B. In the first driven roll 19A, the driven rollers 49, 50, 51 are brought into pressure contact with the roll members 41, 42, 43 of the drive roll 19B by turning on the solenoid 71, and the solenoid 71 is turned off. By doing, driven roller 4
9, 50, 51 and the roll member 41 of the drive roll 19B,
The pressure contact state with 42 and 43 is released. As shown in FIG. 7, the solenoid 71 is provided with a spring 72 for releasing the pressed contact state between the driven rollers 49, 50, 51 and the roll members 41, 42, 43 of the drive roll 19B.

In the fourth embodiment, the drive motor 44 of the triroll 19 of the sheet reversing device 14 is driven and the drive roll 19B of the triroll 19 is rotationally driven in the single-sided copy reversal discharge mode in the image forming apparatus. Discharge passage 1
The switching member 27 arranged in 6 is pulled up by a solenoid (not shown) and switched from the discharge passage 16 side to the feed passage 17 side. Then, in this state, the image forming operation is started, and the recording sheet S fixed by the fixing device 13 is conveyed to the feeding path 17 by switching the conveying direction by the switching member 27. At that time, the length of the recording sheet S in the conveying direction is determined by the exit roll 1 of the fixing device 13.
When it is longer than the path length between the 3a and the forward / reverse rolls 21 and 22, the solenoid 71 is turned off as shown in FIG.
In this state, rotatable driven rollers 49, 50, 51 fixed only in the thrust direction with respect to the fixed shaft 48 of the first driven roll 19A located in the feed passage 17 and the drive shaft 40 of the drive roll 19B. A roll member 41 fixed to
The nip state with 42 and 43 is released.

As a result, the recording paper S fixed by the fixing device 13 is transferred to the exit roll 13 of the fixing device 13.
It is conveyed to the forward / reverse rolls 21 and 22 by a through the feed passage 17 and the reverse passage 25. Then, the recording paper S is temporarily guided into the drawing path 25A by the forward / reverse roll 22 in the normal rotation state, but the upper end of the recording paper S is located above the lower end of the shield plate 31 of the switching member 20. positioned.

The recording paper S once guided into the pull-in path 25A by the forward / reverse roll 22 has its upper end located above the lower end of the shield plate 31 of the switching member 20, and therefore the forward / reverse roll. It is conveyed to the reversal passage 25 again by reversing 22. The recording sheet S, with the surface on which the toner image is formed facing downward,
It is guided to a nip portion composed of a drive roll 19B and a second driven roll 19C arranged in the delivery passage 18 through the reversing passage 25, and is conveyed to the outside of the apparatus by the conveying force of the drive roll 19B. As a result, the recording sheet S
Is discharged to the outside of the apparatus by the drive roll 19B and the second driven roll 19C with the surface on which the toner image is formed facing downward.

At this time, the driving roll 19B of the triroll 19 is set to a rotation speed higher than the process speed of the image forming apparatus, and when the leading end position of the recording sheet S reaches the driving roll 19B after reversal, The nip between the forward / reverse roll 22 and the pinch roll 21 is released, and the recording sheet S is conveyed only by the driving force of the driving roll 19B. As a result, immediately after the nip between the forward / reverse roll 22 and the pinch roll 21 is released, the recording paper S is conveyed by the drive roll 19B whose rotation speed is set to a high speed, so that an FCOT (First Copy Out) is obtained.
put Time: the time until the first copy is ejected can be shortened, and the productivity of the image forming apparatus can be improved.

On the other hand, the length of the recording sheet S in the conveying direction is determined by the exit roll 13a of the fixing device 13 and the forward / reverse roll 2.
If it is shorter than the path length between the first and second recording sheets 22, the front end of the recording sheet S is detected by the detection unit 2 of the detection sensor 28 as shown in FIG.
9, the solenoid 71 of the triroll 19 is turned on immediately before the trailing edge of the recording sheet S passes through the exit roll 13a of the fixing device 13, and the first driven roll 19A of the first feed roll 19A located in the feed path 17 is turned on. A rotatable driven roller 49, 5 fixed to the fixed shaft 48 only in the thrust direction.
0 and 51 and the roll members 41, 42 and 43 fixed to the drive shaft 40 of the drive roll 19B are nipped. Immediately after the leading edge of the recording sheet S is nipped between the forward / reverse roll 22 and the pinch roll 21, the solenoid 71 is turned off, and the first driven roll 19A and the drive roll 19B located in the feeding passage 17 are placed. Release the nip with
The recording sheet S is conveyed to the drawing path 25A only by the forward / reverse roll 22 and the pinch roll 21. The subsequent operation is similar to the above case.

As described above, in the fourth embodiment, the first
Nip between the driven roll 19A and the drive roll 19B of
The nip between the first driven roll 19A and the drive roll 19B is released immediately before the recording sheet S is clamped by the exit roll 13a of the fixing device 13 located on the upstream side, and the nip between the first driven roll 19A and the drive roll 19B is released. The forward / reverse roll 22 and the pinch roll 21 located on the downstream side are configured to perform at the moment when the leading edge of the recording sheet S is nipped. Therefore, there is a speed difference between the fixing device 13 and the exit roll 13a and the drive roll 19B on the feeding side, or between the drive roll 19B and the forward / reverse roll 22 due to the setting of the apparatus or the wear of the roll. In addition, the time during which the image forming surface of the recording paper S is simultaneously nipped by the drive roll 19B and the roll positioned on the upstream side or the downstream side thereof can be made substantially zero, and the drive roll 19B can be used by the drive roll 19B. Since it is possible to substantially limit the location where slipping may occur by nipping the sheet to only the non-image area near the edge of the recording sheet S, it is possible to prevent deterioration of image quality.

Further, by setting the sheet holding force of the drive roll 19B of the triroll 19 to be larger than the holding force of the roll positioned on the upstream side or the downstream side, slipping of the recording sheet S can be surely prevented. This makes it possible to prevent deterioration of image quality more thoroughly.

Fifth Embodiment FIG. 9 shows a fifth embodiment of the present invention. In the first embodiment, only the drive roll 19B of the triroll 19 is driven by the drive motor 44. ,
In the fifth embodiment, of the first, second and third roll carrying means, two roll carrying means are independently drivable, and the rotatably driven roll carrying means is driven to rotate. The roll member of the other roll means that comes into pressure contact with the roll member is constituted by a roll member rotatably attached to the shaft member.

9 to 12 show a sheet reversing device used in the image forming apparatus constructed as described above.

A triroll 19 forming a part of the sheet reversing device 14 is arranged between the feeding passage 17 and the feeding passage 18 of the sheet reversing device 14. The triroll 19 includes a first drive roll 19A as a first roll transport unit and a second drive roll 19A as a second roll transport unit.
So that the nip portion between the second driving roll 19B and the driven roll 19C as the third roll conveying means is located in the delivery passage 18. 1st, 2nd drive roll 19A, 19
B and the driven roll 19C are arranged in pressure contact with each other.

The triroll 19 is, as shown in FIG. 9, the first drive roll 1 located on one side of the feeding passage 17.
9A is a roll member 81 fixed to the drive shaft 80.
And the drive shaft 8 of the first drive roll 19A.
Zero is rotationally driven by the first drive motor 82, the drive gear 83, and the driven gear 84. In addition, the above-mentioned inlet passage 1
7 and a second drive roll 19 located between the delivery passage 18
B is a driven roller 86 rotatably attached to the drive shaft 85 and in pressure contact with the roll member 81 of the first drive roll 19A.
And two roll members 87, 88 fixed to the drive shaft 85 at predetermined intervals on both sides of the driven roller 86, and the drive shaft 85 of the second drive roll 19B.
Are driven to rotate by the second drive motor 89, the drive gear 90, and the driven gear 91. Further, a driven roll 19 located on one side of the delivery passage 18 is provided.
C is rotatably attached to the fixed shaft 92 and is composed of two driven rollers 93 and 94 which are in pressure contact with the two roll members 87 and 88 of the second drive roll 19B. The fixed shaft 92 of this driven roll 19C is Frame 95 of image forming apparatus
It is fixed to.

With the above-described structure, the sheet reversing device of the image forming apparatus configured as described above operates as follows.
Even when the paper conveyance speed is changed before and after the paper is reversed, the structure is simple, and it is possible to prevent cost increase and prevent the generation of impulse noise. Even if the paper is sandwiched between the input side and the output side at the same time, the speed of the output side paper can be increased, and unnecessary rotation of the roll can be avoided to reduce noise and stain the image forming surface. It is possible to prevent the occurrence of.

That is, in the single-sided copy reversal discharge mode in the image forming apparatus, as shown in FIG. 9, two drive motors 82, 8 of the triroll 19 of the paper reversing device 14 are used.
9 is driven to rotate both the first driving roll 19A on the feeding side and the second driving roll 19B on the feeding side of the triroll 19, but the rotation speed of the second driving roll 19B on the feeding side is , Is set higher than the rotation speed of the first drive roll 19A on the feeding side. As shown in FIG. 10, the switching member 27 arranged in the discharge passage 16 is pulled upward by a solenoid (not shown) and switched from the discharge passage 16 side to the feed passage 17 side. And the fixing device 13
The recording sheet S, which has been subjected to the fixing process in step 1, is switched to the transport direction by the switching member 27 and is transported to the feeding path 17,
The first drive roll 19A located in the feeding passage 17
And a driven roller of the second drive roll 19B on the delivery side, which is fixed only in the thrust direction with respect to the drive shaft, and is guided to the nip portion. It is guided to the forward / reverse rotation roll 22 in the forward rotation state via 25. As a result, the recording sheet S is
Although it is once guided into the pull-in path 25A by the forward / reverse roll 22 in the forward rotation state, the upper end of the recording sheet S is located above the lower end of the shield plate 31 of the switching member 20.

During this time, the fixing device 13 and its conveying roll 1
3a and the first driving roll 19A on the feeding side, or between the first driving roll 19A and the forward / reverse rotation roll 22, there is a speed difference due to the setting of the device or the wear of the roll, Even if the recording sheet S slips in the nip of the first driving roll 19A on the side, the surface of the recording sheet S on which the toner image is formed is, as shown in FIGS. Driven roller of drive roll 19B 86
The first drive roll 19A does not have a roll that sandwiches the recording paper S in opposition to the roll members 87 and 88 of the second drive roll 19B. The driven roller 86 only rotates together, the toner image surface of the recording sheet S is not rubbed, and the toner image surface is not stained.

The recording paper S once guided to the pull-in path 25A by the forward / reverse roll 22 has its upper end located above the lower end of the shield plate 31 of the switching member 20, so that the recording paper S is reversed in the forward / reverse direction. It is again conveyed to the reversing passage 25 by the roll 22, and is guided through the reversing passage 25 to the nip portion composed of the second driving roll 19B and the driven roll 19C arranged in the delivery passage 18, It is transported to the discharge roll 15 by the transport force of the drive roll 19B. At that time, the second drive roll 19B is
Since the recording sheet S is driven at a higher rotation speed than the first drive roll 19A, when the recording sheet S is conveyed to the first drive roll 19A, the forward / reverse roll 22 for reverse rotation is accelerated or the recording sheet S is rotated. Immediately after the tip is nipped by the second drive roll 19B, the forward / reverse roll 22 and the pinch roll 21
It is designed to release the nip between and.

As described above, in the triroll 19, the second drive roll 19B can be driven at a higher rotation speed than the first drive roll 19A, and therefore the recording sheet S
Can be discharged at high speed, and even if it is configured to change the paper conveyance speed before and after reversing the paper, the structure is simple and costs are increased, and impulse noise is generated. It is possible to prevent this, and even if the paper is pinched by the sending side and the sending side at the same time, the speed of the sending side paper can be increased.

A speed difference exists between the forward / reverse roll 22 and the second drive roll 19B on the delivery side, or between the second drive roll 19B on the delivery side and the discharge roll 15 for the same reason as above. Then, even if a slip occurs in the nip portion of the second driving roll 19B on the sending side, the surface of the recording paper S on which the toner image is formed contacts the driven roll 19C as shown in FIGS. 11 and 12. Therefore, since the driven roll 19C is rotated together with the slipping recording sheet S, the toner image surface is not contaminated.

Further, in the double-sided copy mode of the image forming apparatus, as shown in FIG. 9, only one drive motor 42 of the triroll 19 of the paper reversing device 14 is driven, and the first side of the triroll 19 on the feeding side is driven. Drive roll 19A
Only are driven. Further, as shown in FIG. 10, the switching member 27 arranged in the discharge passage 16 is pulled upward by a solenoid (not shown) and switched from the discharge passage 16 side to the feed passage 17 side. The operation until the roll is guided to the forward / reverse roll 22 in the forward rotation state is the same as that in the single-sided copy reverse discharge mode. When the reversal timing of the recording paper S is delayed from the one-sided copy reversal discharge mode, the upper end of the recording paper S is at the lower end of the switching member 20 disposed at the branch portion of the reversing passage 25 and the double-sided / multiple recording passage 26. Passing through the shield plate 31 attached to the switching member 20
Is switched to the double-sided / multi-recording passage 26 side by its own weight. Therefore, the recording sheet S conveyed again by the forward / reverse roll 22 in the reverse rotation state is conveyed via the switching member 20 to the double-sided / multiple recording path 26 with the surface on which the toner image is formed facing up. . The recording sheet S is conveyed again to the image forming unit with the surface on which the toner image is formed facing down via the double-sided / multiple recording path 26 formed to be curved and folded back. On the back of
A toner image is formed. The subsequent operation is the same as in the single-sided copy normal discharge mode. The recording sheet S having the toner images formed on both sides passes through the fixing device 13 and then the discharge path 16
It is discharged to the outside of the apparatus by the discharge roll 15 via the. Therefore, in this double-sided copy mode, it is not necessary to drive the drive roll 19B on the sending side, and the driven roll 19B
Since C also does not rotate following, noise can be reduced accordingly.

The other structure and operation are the same as those of the first embodiment, and therefore the description thereof is omitted.

Fifth Embodiment FIG. 13 shows a fifth embodiment of the present invention. In this fifth embodiment, one roll member 201 of the first drive roll 200 is driven by an intermediate driven member. Roll 20
While being pressed against the second driven roller 203, the two roll members 205 and 206 of the second drive roll 204 are arranged between the two driven rollers 202 of the driven roller 202.
It is configured to be in pressure contact with 7, 208.

The rest of the configuration and operation are similar to those of the above-mentioned embodiment, and therefore their explanations are omitted.

[0066]

According to the present invention, which has the above-described structure and operation, the structure is simple, and the cost can be reduced even when the conveying speed of the sheet is changed before and after the sheet is reversed. It is possible to prevent the occurrence of a rise and an impulsive sound, and moreover, even when the paper is sandwiched between the sending side and the sending side at the same time, the sending side paper can be accelerated. It is possible to provide a sheet reversing device that can avoid unnecessary rotation of a roll, can generate low noise, and can prevent the image forming surface from being contaminated.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a sheet reversing device according to the present invention.

FIG. 2 is a configuration diagram showing an image forming apparatus to which a sheet reversing device according to an embodiment of the present invention is applied.

FIG. 3 is a configuration diagram showing an embodiment of a sheet reversing device according to the present invention.

FIG. 4 is a timing chart showing a second embodiment of the sheet reversing device according to the present invention.

FIG. 5 is a configuration diagram of essential parts showing a third embodiment of a sheet reversing device according to the present invention.

FIG. 6 is a configuration diagram of essential parts showing a third embodiment of a sheet reversing device according to the present invention.

FIG. 7 is a configuration diagram showing a fourth embodiment of a sheet reversing device according to the present invention.

FIG. 8 is a timing chart showing a fourth embodiment of the sheet reversing device according to the present invention.

FIG. 9 is a perspective view showing a fifth embodiment of the sheet reversing device according to the present invention.

FIG. 10 is a configuration diagram showing a fifth embodiment of a sheet reversing device according to the present invention.

FIG. 11 is a schematic diagram showing a fifth embodiment of the sheet reversing device according to the present invention.

FIG. 12 is a schematic diagram showing a fifth embodiment of the sheet reversing device according to the present invention.

FIG. 13 is a schematic diagram showing a sixth embodiment of the sheet reversing device according to the present invention.

FIG. 14 is a perspective view showing a conventional sheet reversing device.

FIG. 15 is a schematic view showing a conventional sheet reversing device.

FIG. 16 is a schematic view showing a conventional sheet reversing device.

[Explanation of symbols]

14 Paper Reversing Device, 19 Triroll, 19A 1st
Driven roll, 19B drive roll, 19C first driven roll.

Claims (2)

[Claims] 1. A first roll conveying means and a second roll conveying means, which are configured by attaching a roll member to a shaft-like member, and the first roll conveying means and the second roll conveying means are pressed against each other. At the same time, the second roll transport means and the third roll transport means are brought into pressure contact with each other, and the sheet transport direction at the press contact portion between the first roll transport means and the second roll transport means, and the second roll transport In the paper reversing device, in which the conveyance direction of the sheet at the pressure contact portion between the first roller conveyance section and the third roller conveyance section is set to be substantially opposite, and the conveyance direction of the sheet can be reversed, the second roll conveyance section is provided. A sheet reversing device, which is configured to rotate and drive and to release a pressure contact state of either the first or the second roll transport unit that is in pressure contact with the second roll transport unit. 2. A first, a second, and a third roll transporting means constituted by attaching a roll member to an axial member, and the first roll transporting means and the second roll transporting means are pressed against each other. At the same time, the second roll transport means and the third roll transport means are brought into pressure contact with each other, and the sheet transport direction at the press contact portion between the first roll transport means and the second roll transport means, and the second roll transport In the sheet reversing device capable of conveying the sheet in the state in which the sheet conveying direction is reversed by setting the sheet conveying direction in the pressure contact portion between the sheet conveying unit and the third roll conveying unit to be substantially opposite to each other, Among the third roll transporting means, two roll transporting means are configured to be independently drivable, and the roll members of the other roll means are in pressure contact with the rotatively driven roll member of the rotatively driven roll transporting means. The axial The roll-shaped member is rotatably attached to the member, and the transport speed of the roll transport unit located on the paper delivery side is set higher than the transport speed of the roll transport unit located on the paper transport side. A paper reversing device characterized by the above.