JP2002169403A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device where recording material is fed from a fixing device to a re-feeding means without increasing the number of parts while restraining the lowering of the durability and the throughput of the fixing device. SOLUTION: A fixing motor 10d drives to rotate a fixing belt 10a and a pressure roller 10b and also drives to rotate paper ejection rollers 11 and 12 in a positive direction or a negative direction, and the rollers 11 and 12 feed transfer material S in a paper ejection direction at the time of rotating in the positive direction and feed it to a double-sided means 16A at the time of rotating in the negative direction. The belt 10a and the roller 10b are driven to be rotated in a direction where the transfer material S is fed toward the rollers 11 and 12 regardless of the rotating directions of the rollers 11 and 12 by the motor 10d.

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 such as an electrophotographic system.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus employing an electrophotographic system or the like has a latent image carrier for carrying a latent image, and a developer is applied to the latent image carrier to form a latent image on the developer image. A developing device that visualizes the developer, a transfer unit that transfers the developer image by the developing device to a recording material, and the developer by heating and pressing the recording material that has received the transfer of the developer image by the transfer unit. A fixing device for fixing the image to the recording material, and a fixing device for transferring the developer image onto one surface by a transfer unit. After the fixing process, the developer image is formed again on the other surface of the recording material. There is known an image forming apparatus including a re-conveying unit capable of conveying a recording material to the transfer unit.

In such an image forming apparatus, the fixing device includes a fixing body and a pressure body that are pressed against each other to form a nip and rotate, and a driving unit that rotationally drives the fixing body or the pressure body. The non-fixed image is fixed on the recording material by heating and pressing while nipping and conveying the recording material in the nip.

An image forming apparatus 100A as an example of such an image forming apparatus will be described with reference to FIG.

In the image forming apparatus 100 A, a transfer material S, which is a recording material on which a toner image, which is a developer image, has been transferred to one surface by a transfer unit 102, has the toner image fixed by a fixing device 103. Later, the image forming apparatus 100
The sheet is conveyed to a double-sided device 200A provided separately from the A body.

The transfer material S conveyed to the double-sided apparatus 200A is conveyed to a conveyance path 202 for forming an image on the other side, and when the rear end of the transfer material S in the conveyance direction reaches the branch portion 204. And is transported to the transport path 203.

Thereafter, the transfer material S is corrected for skew and lateral displacement by a double-sided means (not shown) as a re-conveying means of the double-sided portion 206, and is fed again to the registration roller pair 101.

The transfer material S re-fed to the pair of registration rollers 101 has the toner image transferred and fixed on the other surface, is discharged outside the machine, and images are obtained on both surfaces.

[0009]

However, in the above-described image forming apparatus 100A, a plurality of drive motors (see FIG. 1) for driving the conveying rollers 205-1 to 205-4 in the double-sided apparatus 200A and the double-sided means of the double-sided section 206 are provided. (Not shown) must be arranged in the double-sided device 200A, which causes problems such as an increase in the number of components and an increase in the size of the entire device.

In order to solve the above-mentioned problem, it is possible to switch between a positive direction and a negative direction of a driving means for rotating a fixing body or a pressure body of a fixing device, and perform a fixing process when the driving means rotates in the positive direction. It is conceivable to use the rotational driving force during rotation to drive the conveying rollers 205-1 to 205-4 and the double-sided means of the double-sided portion 206. However, when the fixing unit and the pressing unit are rotated in the opposite direction to the rotation direction during the fixing process when the driving unit rotates in the negative direction, an extra load is applied to the fixing unit and the pressing unit, and the durability of the apparatus is reduced. In addition, the fixing process cannot be performed and the throughput decreases.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus which can convey a recording material from a fixing device to a re-conveying unit without increasing the number of parts while suppressing a decrease in durability and throughput of the fixing device. .

[0012]

According to the present invention, an object of the present invention is to provide a latent image carrier for carrying a latent image, and developing the latent image by applying a developer to the latent image carrier. A developing device that visualizes the developer, a transfer unit that transfers the developer image by the developing device to a recording material, and the developer by heating and pressing the recording material that has received the transfer of the developer image by the transfer unit. A fixing device for fixing the image to the recording material, and a fixing device for transferring the developer image onto one surface by a transfer unit. After the fixing process, the developer image is formed again on the other surface of the recording material. An image forming apparatus comprising: a re-conveying unit capable of conveying a recording material to the transfer unit, wherein the fixing device presses each other to form a nip and rotates, and a fixing body and a pressing body; and the fixing body or the fixing body. And a driving means for rotationally driving the pressurizing body. In an image forming apparatus in which the unfixed image is fixed to the recording material by heating and pressing while nipping and conveying the recording material in the nip, a forward direction in which the recording material after the fixing process on one surface is directed to a re-conveying unit And a driving unit that drives the fixing member and the pressurizing member to rotate, and drives the conveyance member so that the conveyance direction of the recording material by the conveyance member can be switched to a forward direction or a reverse direction. The conveying means conveys the recording material in the paper discharging direction when the driving means drives in the reverse direction, and the fixing body and the pressing body are related to the conveying direction of the conveying member by the driving means. This is achieved by the first invention in which the recording material is rotatably driven in a direction for conveying the recording material toward the conveying member.

According to the present invention, the above object is achieved in the first aspect by the fixing device, wherein the fixing device comprises a heating means for heating the fixing body, a temperature detecting means for detecting the temperature of the fixing body, Control means for controlling the heating drive of the heating means so that the temperature detected by the means becomes a predetermined temperature,
The present invention is also achieved by the second invention in which the control means is set so that the heating drive of the heating means is controlled even when the transport member is driven in the reverse direction by the drive means.

[0014]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a sectional view showing a schematic configuration of a color image forming apparatus according to an embodiment of the present invention.

In this color image forming apparatus, as shown in FIG. 1, four photosensitive drums 1 (1a, 1a,
1b, 1c, 1d), and a charging means 2 (2a, 2) for uniformly charging the surface of the photoconductor drum 1 in order according to the rotation direction around each photoconductor drum 1.
b, 2c, 2d), an exposure unit 3 (3a, 3b, 3c, 3d) for irradiating a laser beam based on image information to form an electrostatic latent image on the photosensitive drum 1, and a toner on the electrostatic latent image Developing device 4 (4)
a, 4b, 4c, 4d), transfer rollers 5 (5a, 5b, 5c, 5d) as transfer means for transferring the toner image on the photosensitive drum 1 onto a transfer material as a recording material, and the surface of the photosensitive drum 1 after transfer The cleaning means 6 (6a, 6b, 6c, 6d) for removing the post-transfer toner remaining in the image forming apparatus is provided to constitute an image forming means.

Here, the photosensitive drum 1, the charging means 2, the developing device 4, and the cleaning means 6 for removing toner are integrally formed as a cartridge, and the process cartridge 7 (7
a, 7b, 7c, 7d).

The transfer material S fed from the feeding unit 8 is
After being transferred to the image forming unit by the transfer and transfer unit 9 constituted by a transfer belt, the respective color toner images are sequentially transferred and the color image is recorded, the image is fixed by the fixing device 10 and the transfer member is a pair of rotating members. Barrel discharge rollers 11, 1
2, the paper is discharged to the paper discharge unit 13.

In the case of double-sided printing, before the transfer material S subjected to the fixing process by the fixing device 10 is discharged by the discharge rollers 11 and 12, the discharge rollers 11 and 12 are rotated in reverse. Is transported to the duplex transport path 15 (in the direction of arrow A). The transfer material S conveyed to the double-sided conveyance path 15 passes through the skew feeding roller 16a by a double-sided means 16A as a re-conveying means at the front of the apparatus main body, is conveyed vertically downward to the U-turn roller 17, and And registration roller 8
The sheet is re-conveyed to the image forming section by d.

Next, the configuration and operation of each section will be described sequentially.

First, the feeding section 8 will be described.

The feeding section 8 includes a sheet feeding cassette 8a, a multi sheet feeding tray 8b, a multi sheet feeding section 8c, and a registration roller 8.
d.

The paper feed cassette 8a stores a plurality of transfer materials S and is loaded at the bottom inside the apparatus main body. Paper cassette 8
When an image is formed from a, the transfer material S is separated and conveyed one by one by a cassette pickup roller 8a1, and is conveyed to an image forming section of the image forming means by a cassette conveyance roller 8a2 and a registration roller 8d.

The multi-sheet feeding tray 8b is usually stored in the front of the apparatus main body, but when used, the multi-sheet feeding tray 8b is rotated and opened from the apparatus main body to set a plurality of transfer materials S. When forming an image from the multi-sheet feed tray 8b, the transfer material S is separated and conveyed one by one by the multi-pickup roller 8c1, and conveyed to the image forming section by the multi-conveyance roller 8c2 and the registration roller 8d.

The separation and conveyance of sheets in the sheet feeding cassette 8a and the multi-feeding section 8c are performed by a sheet feeding motor (not shown) in the feeding section via a gear drive train.

Next, the image forming section will be described.

The photosensitive drum 1 as an image carrier has an organic photoconductive layer (OP) on the outer peripheral surface of an aluminum cylinder.
C). Photoconductor drum 1
Is rotatably supported at both ends by flanges, and is driven to rotate in a counterclockwise arrow direction by transmitting a driving force from a driving motor (not shown) to one end.

Each charging means 2 is a conductive roller formed in the shape of a roller. The roller is brought into contact with the surface of the photosensitive drum 1 and a charging bias voltage is applied by a power supply (not shown). This is for uniformly charging the surface of the photosensitive drum 1.

The exposure means 3 has a polygon mirror, and this polygon mirror has a laser diode (not shown).
Irradiates image light corresponding to the image signal.

The developing device 4 is adjacent to the toner storage units 4a1, 4b1, 4c1, 4d1 storing toners of the respective colors of black, cyan, magenta, and yellow, and the surface of the photosensitive drum 1, and a driving unit (not shown). And developing rollers 4a2, 4b2, 4c2, 4d2, etc., which perform development by applying a developing bias voltage from a developing bias power supply (not shown).

In addition, transfer rollers 5a, 5 which are opposed to the four photosensitive drums 1a, 1b, 1c, 1d and contact the transfer conveyance belt 9a are provided inside a transfer conveyance belt 9a to be described later.
b, 5c, and 5d are respectively provided. These transfer rollers 5 are connected to a transfer bias power supply (not shown), and a positive charge is applied from the transfer roller 5 to the transfer material via the transfer conveyance belt 9a.
The negative color toner images on the photoconductor drum 1 are sequentially transferred to the transfer material in contact with the photoconductor drum 1 to form a color image.

Next, the configuration for transporting the transfer material S will be described.

The transfer material S is supplied from a feeding unit 8 to a transfer / conveying unit 9.
To the image forming unit.

The transfer / conveyance belt 9a as a transfer material carrier constituting the transfer / conveyance means 9 is stretched and supported by four rollers of a driving roller 9b and driven rollers 9c, 9d and 9e.
The photosensitive drums 1a, 1b, 1c, and 1d are arranged to face each other.

The transfer conveyance belt 9a is driven by a driving roller 9b so that the transfer material S is electrostatically attracted to the outer peripheral surface facing the photosensitive drum 1 and the transfer material S is brought into contact with the photosensitive drum 1.
It moves cyclically. As a result, the transfer material S is transported to the transfer position by the transfer transport belt 9a, and the toner image on the photosensitive drum 1 is transferred.

At the most upstream position of the transfer conveyance belt 9a in the conveyance direction of the transfer material S, an attraction roller 9f for holding the transfer material S together with the transfer conveyance belt 9a and adsorbing the transfer material S to the transfer conveyance belt 9a. Are arranged. Transfer material S
At the time of transfer, a voltage is applied to the suction roller 9f to form an electric field between the transfer roller 9f and the opposite grounded roller 9c, causing dielectric polarization between the transfer transfer belt 9a and the transfer material S. Thus, an electrostatic attraction force is generated between the two.

Next, the auxiliary transport structure of the transfer material S will be described.

In the present embodiment, when the transfer material S is conveyed by the transfer / conveyance belt 9a, the transfer material S is configured not to be peeled off from the transfer / conveyance belt 9a by the auxiliary member.
This auxiliary member is on the side of the transfer / conveying belt 9a that carries the transfer material, and also functions as a moving unit that moves the transfer / conveying belt 9a to the second position as described later.

More specifically, a plurality of auxiliary conveying rollers 14 are provided as auxiliary members rotatable and rotatable on the front side of the transfer / conveying belt 9a. The auxiliary conveying roller 14 is provided with a cam mechanism (not shown). ) So as to be integrally movable in the left-right direction.

When performing color recording, the auxiliary transport roller 14 is retracted to the left and separated from the transfer transport belt 9a. On the other hand, when performing monochrome recording, the cam mechanism operates to move the auxiliary transport roller 14 to the right, abut the transfer transport belt 9a, and push the belt 9a. As a result, although the transfer conveyance belt 9a is still in contact with the black photosensitive drum 1d,
The photosensitive drums 1a, 1b, and 1c are separated from each other.

Next, the fixing device 10 will be described.

The fixing device 10 fixes the image formed on the transfer material S on the transfer material S by applying heat and pressure to the image.

The fixing device 10 has a fixing belt 10a as a cylindrical fixing member having an electromagnetic induction heating layer, and the fixing belt 10a has a built-in magnetic field generating means including an exciting coil and a T-shaped magnetic core. Is guided by the belt guide member 10c.

The fixing device 10 has a pressing roller 10b as an elastic pressing member. The pressing roller 10b has a predetermined width with a predetermined pressing force against the belt guide member 10c with the fixing belt 10a interposed therebetween. A fixing nip portion N is formed.

In the fixing device 10, the pressure roller 10
b is rotationally driven by a fixing motor 10d, which will be described later, and the cylindrical fixing belt 10a is rotated accordingly, and electromagnetic induction heat of the fixing belt 10a is generated by power supply from an excitation circuit (not shown) to the excitation coil. Done.

In a state where the temperature of the fixing nip N is raised to a predetermined temperature and the temperature is controlled, the transfer material S on which the unfixed toner image is conveyed from the image forming unit is applied to the fixing belt 10a of the fixing nip N. The fixing roller 10b is introduced with the image surface facing upward, that is, the fixing belt 10a is introduced in opposition to the surface of the fixing belt 10a.
The fixing nip portion N is transported together with the fixing belt 10a in close contact with the outer surface of the fixing belt 10a.

In the process in which the transfer material S is nipped and conveyed in the fixing nip portion N together with the fixing belt 10a, the unfixed toner image on the transfer material S is heated by the electromagnetic induction heat of the fixing belt 10a and is transferred to the transfer material S. It is heated and fixed.

Next, an operation when an image is recorded by the image forming apparatus having the above configuration will be described.

First, when performing color image recording, the auxiliary transport roller 14 is retracted to the left as shown in FIG. In this state, the transfer conveyance belt 9a is in contact with the four photosensitive drums 1a, 1b, 1c, 1d (first
Position), when the transfer material S fed from the feeding unit 8 is adsorbed and conveyed to the transfer / conveyance belt 9a, the toner images of each color are sequentially transferred by the image forming means to form a color image, and the image is fixed. After the image is fixed by the device 10, the sheet is discharged to the sheet discharge unit 13.

On the other hand, in the case of black printing (monochrome printing), when monochrome image recording by only the black photosensitive drum 1d is selected, a cam mechanism (not shown) is driven as shown in FIG. Then, the auxiliary transport roller 14 is moved rightward, and the auxiliary transport roller 14 pushes the transfer transport belt 9a, thereby transferring the transfer transport belt 9a from the other photosensitive drums 1a, 1b, 1c except the black photosensitive drum 1d. Separate.

In this state, the black toner image formed on the black photosensitive drum 1d is transferred to a transfer material, and the fixing device 1
After the image is fixed to 0, the sheet is discharged to the sheet discharge unit 13.

Next, the double-sided conveyance operation of the transfer material S during the double-sided image formation will be described.

The transfer material S having the toner image transferred to the surface as described above is fixed by the fixing device 10 and is discharged to the paper discharge unit 13 while the discharge sensor 18 passes through the rear end of the transfer material S. Detect. The paper discharge rollers 11 and 12 stop rotating after a predetermined time from when the paper discharge sensor 18 detects the rear end of the transfer material S to when the rear end of the transfer material S reaches the branch portion P. The rear end of the transfer material S branches to the double-sided conveyance path 15 due to the stiffness,
The transfer material S is conveyed to the double-sided portion 19 by rotating the discharge rollers 11 and 12 in reverse.

The double-sided portion 19 includes a skew feeding roller 16a, a horizontal registration guide 16b, a horizontal registration reference member 16c, and a conveyance guide (not shown), which are double-sided means 16A described later.
Consists of

The transfer material S conveyed to the double-sided portion 19 is corrected by the double-sided means 16A for skew (inclination) and lateral displacement of the transfer material S, and then conveyed by the U-turn roller 17 to be transferred to the registration roller. The sheet is fed again to 8d.

The transfer material S re-fed to the registration roller 8d has a toner image transferred to the non-image forming surface (the other surface) in the same manner as the front surface (the one surface), and the image is recorded. The image is fixed by the apparatus 10, and the sheet is discharged to the sheet discharge section 13 by the sheet discharge rollers 11 and 12, and the double-sided printing on the front side and the back side is completed.

The fixing device of the image forming apparatus according to the present embodiment will be described in detail with reference to FIGS.

FIG. 2 is a perspective view for explaining the driving of the fixing device 10.

In FIG. 2, A shows the state of fixing the unfixed toner image on the front surface and the state of transport of the transfer material. At this time, the fixing motor 10d and the pressure roller 1
0b, the paper discharge rollers 11 and 12 rotate clockwise in the figure,
The transfer material S is transported in the direction of the arrow. As described above, after the paper ejection sensor (not shown) detects the rear end of the transfer material S, the paper ejection roller 12 is rotated in reverse by rotating the fixing motor 10d in reverse. As shown in FIG. 2B, the transfer material S is conveyed to both sides while changing the conveyance direction in the direction of the arrow. The discharge rollers 11 and 12 transport the transfer material S to the double-sided means 16A of the double-sided portion 19 shown in FIG. Also, in the state of FIG. 2B, the pressure roller 10b is rotating in the same direction as the state of A. In the state of A, the one-way gear 10el,
The drive is transmitted to the pressure roller 10b by the gear 10el of the gear 10e2, and in the state B, the drive is transmitted by the gear 10e2, so that the pressure roller 10b rotates in only one direction.

As shown in FIG. 3, the fixing temperature control is stopped before the timing at which the fixing motor 10d switches from normal rotation to reverse rotation. And 10d of the fixing motor
Is started, and after reaching the target rotation speed, the fixing temperature control is started. By controlling in this manner, the fixing belt 10a is moved before the next transfer material enters the fixing nip portion N.
Can be adjusted to the optimum fixing temperature.

As described above, since the rotation direction of the pressure roller 10b is only one direction, the fixing belt 10a also rotates only in one direction, and the load on the fixing belt 10a can be reduced. 10a can be prevented from being damaged and durability can be improved. Further, by performing the fixing temperature control even while the fixing motor 10d is rotating in the reverse direction, the fixing belt 10a can always maintain the optimum fixing temperature. This eliminates the need to wait until the temperature of the fixing belt 10a reaches a temperature at which fixing can be performed, so that the transfer material can be conveyed without reducing throughput. In addition, since no conveyance roller or the like is required from the paper discharge rollers 11 and 12 to the double-sided means 16A, an increase in the number of parts can be prevented.

[0062]

As described above, according to the first aspect of the present invention, the driving means drives the fixing member and the pressing member to rotate, and at the same time, the conveying direction of the recording material by the conveying member is set to the forward direction. Alternatively, the transport member is driven so as to be switchable in the reverse direction, and the transport unit transports the recording material in the paper discharge direction when the drive unit drives in the reverse direction, and the fixing unit and the pressurizing unit. However, since the recording medium is rotated in the direction in which the recording material is conveyed toward the conveyance member regardless of the conveyance direction of the conveyance member by the driving unit, the reduction in durability and throughput of the fixing device is suppressed. In addition, the recording material can be conveyed from the fixing device to the re-conveying unit without increasing the number of parts.

According to the second invention of the present application,
The driving unit drives the fixing member and the pressurizing member to rotate, and drives the conveyance member so that the conveyance direction of the recording material by the conveyance member can be switched to the forward direction or the reverse direction. The conveying means conveys the recording material in a paper discharging direction when the driving means drives in the reverse direction, and the fixing body and the pressing body move the recording material regardless of the conveying direction of the conveying member by the driving means. In addition to being driven to rotate in the direction in which the conveying member is conveyed toward the conveying member, the heating driving of the heating unit is controlled by the control unit even when the conveying member is driven in the reverse direction by the driving unit. Further, it is possible to convey the recording material from the fixing device to the re-conveying unit without increasing the number of components while suppressing the decrease in the durability and throughput of the fixing device.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view illustrating a schematic configuration of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining driving of a fixing device provided in the image forming apparatus of FIG. 1;

FIG. 3 is a diagram illustrating a relationship between a rotational driving direction of a driving unit of a fixing device and a temperature of a fixing body according to the embodiment of the present invention.

FIG. 4 is a longitudinal sectional view illustrating a schematic configuration of a conventional image forming apparatus.

[Explanation of symbols]

 1a, 1b, 1c, 1d Photoconductor drum (latent image carrier) 4 Developing device 5a, 5b, 5c, 5d Transfer roller (transfer means) 10 Fixing device 10a Fixing belt (fixing member) 10b Pressure roller (pressing member) 10d Fixing motor (driving means) 11, 12 Discharge roller (conveying member) 16A Double-sided means (re-conveying means) N Fixing nip (nip) S Transfer material (recording material)

Continued on front page F term (reference) 2H027 ED19 ED25 EE04 EF09 FA13 2H028 BA06 BA16 BB04 2H033 AA20 AA46 BA10 BB37 CA09 CA40 3F053 BA03 LA02 LA05 LA07 LB03 3F100 AA02 CA16 DA01 DA05 EA05 EA06 EA13

Claims (2)

[Claims] 1. A latent image carrier for carrying a latent image, a developing device for visualizing the latent image as a developer image by applying a developer to the latent image carrier, and a developer image by the developing device Transfer means for transferring the developer image to a recording material, a fixing device for fixing the developer image to the recording material by heating and pressing the recording material to which the developer image has been transferred by the transfer means, and a transfer means Re-transporting means capable of transporting the recording material to the transfer means again so that a developer image is formed on the other surface of the recording material after the fixing process of the recording material having the developer image transferred to one surface thereof An image forming apparatus comprising: a fixing device comprising: a fixing body and a pressing body that press and contact each other to form a nip and rotate; and a driving unit that rotationally drives the fixing body or the pressing body. Heat the recording material while nipping and transporting it with the nip. An image forming apparatus for fixing the unfixed image to the recording material by applying pressure and pressure to the recording material. Drives the fixing member and the pressure member, and drives the transport member so that the transport direction of the recording material by the transport member can be switched to the forward direction or the reverse direction.
The recording material is conveyed in the paper discharge direction when the driving unit is driven in the reverse direction, and the fixing body and the pressing body direct the recording material toward the conveyance member regardless of the conveyance direction of the conveyance member by the driving unit. An image forming apparatus configured to be driven to rotate in a conveying direction. 2. A fixing device comprising: a heating unit for heating a fixing unit; a temperature detecting unit for detecting a temperature of the fixing unit; and a heating unit for setting the temperature detected by the temperature detecting unit to a predetermined temperature. Control means for controlling the heating drive,
2. The image forming apparatus according to claim 1, wherein the control unit is set so that the heating drive of the heating unit is controlled even when the conveying member is driven in the reverse direction by the driving unit.