JPH049874A - Image forming device - Google Patents

Abstract

PURPOSE:To make a transfer paper passed through a fixation part hardly jammed by providing a posture control mechanism which controls the switching of the posture of a heating roller and a pressure roller so that a transfer sheet passed through both rollers is guided to a first carrying path side or a second carrying path side. CONSTITUTION:A first branch 18 is controlled so that the transfer paper passed through a fixing device 16 is ejected to the first carrying path on a paper ejecting tray 6 side or the second carrying path side on a lower second branch 19 side. Besides, a solenoid 38 which turns the supporting plate 35 of the fixing device 16, a solenoid 57 which switches and controls the first branch 18 and the second branch 19 or the like are connected to the CPU 51 of a control part 50. Then, in the case that an image is formed on a first surface, the postures of the heating roller 33 and the pressure roller 34 are controlled so that the transfer sheet is guided to the carrying path on an inversion device side. Besides, they are controlled so that the transfer sheet is guided to a normal ejecting path side in the case that the image is formed on a second surface. Thus, even when curl occurs to the transfer sheet, the occurrence of the jam on the carrying path is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image forming apparatus such as a copying machine, and particularly to an apparatus in which at least two conveyance paths are provided downstream of a fixing section.

[Conventional technology]

For example, in copying machines, devices are provided that have a duplex mode that copies on both the front and back sides of transfer paper, and a composition mode that combines a first image and a second image on one side of transfer paper and makes a copy. There is.

In the duplex mode and composite mode, the primary m7 bee process is performed, and the transfer paper with the toner image transferred passes through the fixing section and then passes through a conveyance path different from the normal ejection path to the intermediate tray. It will be stored. Then, the transfer paper is conveyed from this intermediate tray to the image forming section again, and a secondary copy is performed on the transfer paper. After the transfer paper that has undergone the secondary copying process passes through the fixing section, it is ejected onto the paper ejection tray through a normal ejection path different from the above-mentioned conveyance path.

[Problem to be solved by the invention]

The fixing section in the copying machine as described above is composed of a heating roller having a heater therein, and a pressure roller provided below the heating roller and pressed against the heating roller. Then, the transfer paper on which the toner image has been transferred passes between these rollers, and the ζ toner image is fixed.

In the fixing section, the transfer paper is heated by the heating roller as described above, so the transfer paper is heated and tends to curl toward the upper blade side. On the other hand, does it have a double-sided mode function like N11? j! In I"j° machines, it is necessary to invert the transfer paper and store it on the intermediate tray, so a reversing device is sometimes installed below the fixing section. This reversing device is installed below the fixing section. On the device, if duplex mode is selected,
After the primary copy, it is necessary to transport the transfer paper not through the normal ejection path but toward the reversing device. However, as described above, since the transfer paper tends to curl above the heating roller, it is difficult for the transfer paper to enter the conveyance path on the reversing device side, and jams are likely to occur.

An object of the present invention is to provide an image forming apparatus in which the transfer paper that has passed through the fixing section is less likely to jam.

[Means to solve the problem]

An image forming apparatus according to a first aspect of the present invention includes a fixing section having a heating roller and a pressure roller provided in pressure contact with each other so that a transfer sheet can pass therebetween; and a fixing section downstream of the fixing section in a transfer sheet conveyance direction. The first one is provided on the side and conveys the transfer sheet. It includes a second conveyance path and an attitude control mechanism.

The posture control mechanism switches and controls the postures of both the rollers so that the transfer sheet that has passed through the heating roller and the pressure roller is guided toward the first conveyance path or the second conveyance path.

An image forming apparatus according to a second aspect of the invention further includes, in addition to the configuration of the first aspect, a pressing force adjusting means for changing the pressing force between the heating roller and the pressure roller.

[Operation] In the first invention, the postures of the heating roller and the pressure roller are controlled by the posture control mechanism, and the transfer sheet that has passed through both rollers is guided in a desired direction.

For example, when the double-sided mode is selected as the image forming mode, the postures of the heating roller and the pressure roller are controlled when forming an image on the first side and when forming an image on the second side. First, when forming an image on the first side, the postures of the heating roller and pressure roller are controlled so that the transfer sheet is guided to the conveyance path on the reversing device side.

As a result, even if the transfer sheet is curled by the heating roller, the transfer sheet can easily enter the conveyance path on the reversing device t side, and the occurrence of jams can be suppressed.

Furthermore, when forming an image on the second side, the postures of both rollers are controlled so that they are guided toward the transfer sheet or the normal ejection path, and the transfer sheet that has passed through both rollers is smoothly ejected. .

In this way, since the postures of the heating roller and pressure roller are controlled in the direction in which the transfer sheet is to be conveyed, even if the transfer sheet curls, it is possible to reduce the occurrence of jams on the conveyance path.

In the second invention, in addition to controlling the postures of the heating roller and the pressure roller, it is possible to change the pressing force of both rollers, so it is possible to reduce curling of the transfer sheet and further reduce the occurrence of jams. .

That is, in the example of the double-sided moat, the pressing force of both rollers is kept low when forming an image on the first side.

In addition, the curl of the transfer sheet is reduced, and the transfer sheet can be smoothly fed to the conveyance path on the reversing device side. On the other hand, when forming an image on the second surface, the pressing force between both rollers is made strong. Thereby, the image on the transfer sheet is well fixed.

In this way, by adjusting the pressure contact force, curling can be reduced, and the occurrence of jams is further reduced.

[Embodiment] FIG. 1 shows a copying machine as an image forming apparatus according to an embodiment of the present invention.

In FIG. 1, a document table 2 is fixed to the upper surface of a copying machine main body 1, and a document presser 3 is provided on the document table 2 so as to be openable and closable. A paper feeding power centimeter 4.5 is detachably attached to the rejuvenation side of the copying machine main body l. A paper discharge tray 6 is installed on the left side of the copying machine main body 1, from which copied transfer paper is discharged. Inside the copying machine main body 1, an exposure device 7 for reading a document is provided on the upper side. This exposure device 7 is composed of a light source, a mirror lens unit, and the like. Further, in the center of the copying machine main body 1, a photosensitive drum 8 on which an electrostatic latent image is formed is arranged. A charging device 9, a developing device 10, a transfer device 11, a transfer paper separating device 12, and a cleaning device 13 are arranged in this order around the photoconductor tram 8.

A paper feed conveyance path 14 for supplying transfer paper is provided between the paper feed cassette 4.5 and the image forming section constituted by the photosensitive drum 8 and the like.

Further, between the image forming section and the paper ejection tray 6, a paper ejection transport path 15, a fixing device I6 for fixing the toner image on the transfer paper, and an ejection roller 17 are arranged.

[fixing device] 6 and the ejection roller 17, the first branch 1
8 is provided, and the lower blade thereof is provided with a second branch 19. The first branch 18 controls whether the transfer paper that has passed through the fixing device 16 is discharged to the first conveyance path of the six paper discharge trays or to the second m-th conveyance path on the second branch 19 side below. It is for. In addition, the second branch 19 is
Is the copy mode double-sided? Its attitude is controlled depending on whether it is in Jf photography mode or composite mode.

A reversing device 20 for reversing the transfer paper is provided below the fixing device 16. Moreover, this reversing device 20
A stock paper feeding and transporting device 21 is provided below the stock paper feeding and transporting device 21, and the transfer paper transported by this stock paper feeding and transporting device 21 is transferred to an intermediate stock.

It is designed to be stored in the storage section 22. The intermediate stock section 22 is provided at the bottom of the copying machine main body 1 to temporarily store transfer paper that has been copied on one side or a transfer paper on which a first image has been formed. Also, mid-term strike
At the upper right side of the link section 22, there is a paper refeed transport 1 for transporting the transfer paper from the intermediate link section 22 to the image forming section C.
23 is formed.

Next, the fixing device 16 will be explained in detail with reference to FIGS. 2A and 3.

The fixing device 6 includes a heating roller 33 provided in a housing (not shown) and a pressure roller 34 arranged on the lower blade of the heating roller 33.

A heater is provided inside the heating roller 33.

The heating roller 33 and the pressure roller 34 are rotatably supported in long holes 35a and 35b formed in the support plate 35, respectively. Then, as shown in FIG.
A spring 36 is hooked between the shaft 33a of No. 3 and the shaft 34a of the pressure roller 34 for pressing the rollers 33, 34 together. The support plate 35 has support rods 37 that project laterally.
The support opening 37 is rotatably supported by the frame of the copying machine main body. Also, support)
The operating end of a solenoid 38 is rotatably attached to the top end of the arm 35.

A pressure roller 39 is provided below the pressure roller 34 for adjusting the pressure force between the heated roller 33 and the phase W of the pressure roller 34 . The pressure contact roller 39 is rotatably supported by a support frame 40 fixed to the frame of the main body of the copying machine.

- The copying machine has a control section 50 as shown in FIG. The control unit 50 includes a CPU 51, a ROM 52, an RA
It is equipped with an M53 and an I10 port 54 for connection with the outside. In addition, CPr No. 51 has an I10 boat 54.
A key input section 55, a copy number detection switch, a 56, and other input sections arranged on the top surface of the copying machine main body I are connected through the main body I. Similarly, the CPU 51 includes a solenoid 38 for rotating the support plate 35 of the fixing device 16.
, a solenoid 57 for switching and controlling the first branch and the second branch, and other output parts are connected thereto.

Next, the operation of the copying machine will be explained according to the control flowcharts shown in FIGS. 5A and 5B.

Here, we will mainly explain the operation when the double-sided mode is selected.

In FIG. 5A, when the main switch (not shown) is turned on, initial settings such as setting the number of copies to one and heating the heater are performed in step Sl. Also, at this time, the postures of the heating roller 33 and the pressure roller 34 are returned to the initial state, and become the postures shown in FIG. 2B.

Next, in step S2, it is determined whether the copy start key has been pressed by the operator.

Furthermore, in step S3, it is determined whether the duplex mode has been selected as the image forming mode. Further step S4
Then, it is determined whether a key for other processing has been pressed. When the operation for selecting the double-sided mode is performed, the process moves from step S3 to step S5. Step S
In step 5, the image forming mode is set to double-sided mode. Further, if an operation that requires other processing is performed, the process moves from step S4 to step S6. In step S6, processing is performed according to the operator's instructions, and the step
Return to Room S2.

If the start key is pressed, the process moves from step S2 to step S7 in FIG. 5B. In step 2 step S7,
It is determined whether double-sided printing is set as the image forming mode. If double-sided mode is selected,
The process moves from step S7 to step S8. Step S
8, by turning off the solenoid 38, its operating port 7 is made to protrude. As a result, the support plate 35 rotates counterclockwise around the support rod 37, and assumes the posture shown in FIG. 2A. Further, in this state, the first branch 18 is switched to a position in which it guides the transfer paper downward from the fixing device 16, and the second branch 19 is switched to a position in which it guides the transfer paper to the reversing device 20. ing.

On the other hand, when the support plate 35 is tilted and the heating roller 33 and the pressure roller 34 are in the position shown in FIG. 33 and the pressure roller 34 become weaker.

In this state, the process moves to step S9, and primary copy processing is performed on the surface of the transfer paper. The transfer paper that has been subjected to the primary copying process passes between the heating roller 33 and the pressure roller 34, is guided downward by the first branch 18, and is also sent to the reversing device 20 by the second branch 19. Ru. The transfer paper reversed by the reversing device 20 is stored in the intermediate stock section 22 via the stock paper feeding and conveying device 21. In step SIO, it is determined whether the primary copying process has been completed for the set number of copies, and if it has been completed for the set number of copies, the process moves to step Sll.

In step 51.1, the solenoid 38 is turned on and the actuation rod is retracted. As a result, the support plate 35 rotates clockwise around the support rod 37, and the heating roller 33 and pressure roller 34 are controlled to the posture (normal position) shown in FIG. 2B. Further, in this state, the first branch 18 is in a position to guide the transfer paper toward the paper discharge tray 6 side.

On the other hand, each time the support plate 35 rotates clockwise, the pressure roller 34 and the pressure roller 39 come into contact, and the pressure roller 34 is pushed further upward than the state shown in FIG. 2A.
The +U pressing force between the heating roller 33 and the pressure roller 34 increases.

In this state, the process moves to step S12, and secondary copy processing is performed. In this secondary copying process, a transfer sheet is taken out from the intermediate stock section 22, and an image is formed on the back side of the sheet. The transfer paper that has passed between the heating roller 33 and the pressure roller 34 is guided to the first branch 18 and is discharged to the paper discharge tray 6 side. In step SI3, 2 of the set number of sheets
It is determined whether or not the next copying process has been completed, and if the secondary copying process for the set number of sheets has been completed, the process returns to step S2 shown in FIG. 5A.

On the other hand, if the duplex mode is not selected, the process moves from step S7 to step S14. Step SI4
Then, copy processing is performed in another image forming mode, and when this processing is completed, the process returns to step S2.

In such an embodiment, the transfer paper that passes through the fixing device I6 after the primary copying process curls in the opposite direction to the curve of the lower conveyance path, but the heating roller 33 and the pressure roller 34 curl in the lower direction. Since the transfer paper is tilted to the side, it is easier for the transfer paper to enter the conveyance path. Moreover, both rollers 33, 3 during the primary copy process
Since the pressing force of No. 4 is small, the curling of the transfer paper is small, and jams caused by curling can be reduced.

[Other Examples]

In the embodiment described above, a pressure contact force adjustment mechanism is provided below the pressure roller 34, but even if this pressure contact force adjustment mechanism is not provided, the occurrence of a transfer paper jam can be prevented by controlling the postures of both rollers 33 and 34. can be reduced.

〔Effect of the invention〕

As described above, in the present invention, the postures of the heating roller and pressure roller can be changed, so even if the transfer paper is curled by the heating roller, the transfer paper can be smoothly guided to the conveyance path. It is possible to reduce the occurrence of jams.

Furthermore, when a pressure contact force adjustment means is provided, by weakening the pressure contact force during the first image formation, curling of the transfer paper can be suppressed to a small extent, and the occurrence of jams caused by curling can be further reduced. .

[Brief explanation of drawings]

FIG. 1 is a schematic vertical cross-sectional configuration diagram of a copying machine according to an embodiment of the present invention, FIGS. 2A and 2B are schematic configuration diagrams showing the relationship between the fixing device and the conveyance path, and FIG. 3 is a part of the fixing device. A side view, FIG. 4 is a control block diagram of the copying machine, FIG. 5A, and FIG.
Figure B is a flowchart of the system. 16...Fixing bag! , 1B...first branch, 19...
Second branch, 33... Heating roller, 34... Pressure roller, 35... Support plate, 39... Pressure roller, 40...
...Support frame, 50...Control unit. Patent applicant Yukio Ono, agent of Mita Kogyo Co., Ltd., patent attorney

Claims (2)

[Claims] (1) A fixing section having a heating roller and a pressure roller that are provided in pressure contact with each other so that the transfer sheet can pass therebetween; switching and controlling the postures of both rollers so that the transfer sheet that has passed through the first and second conveyance paths, the heating roller and the pressure roller is guided to the first conveyance path side or the second conveyance path side; An image forming apparatus equipped with an attitude control mechanism and. (2) The image forming apparatus according to claim 1, further comprising a pressing force adjusting means for changing the pressing force between the heating roller and the pressure roller.