JPH11231670A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an intermediate transfer body from being damaged by a spur member or a pawl member at the time of jamming processing and to easily remove transfer material by constituting the spur member and the pawl member as an integral transfer material carrying unit with the intermediate transfer body. SOLUTION: The transfer material carrying unit 300 is formed by integrating the intermediate transfer belt 14a, an intermediate transfer body cleaning device 140, a separation pawl 210 and a carrying part 160 provided with a spur 162. At the time of jamming processing, the unit 300 is separated from a fixing device 17 by the rotation of a lever 301 arranged in a device main body and abutting on the frame body of the belt 14a. The unit 300 butts against a stopper 302 and is locked. The leading end (spur member side) of the unit 300 is opened (lowered) to an opposite side to a photoreceptor drum 10 in a state where the turning shaft B of a driven roller 14e is set as a rotation supporting shaft with respect to a transfer material carrying surface PL1 and the unit 300 is separated from the device 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to copying in which a charging means, an image writing means and a developing means are arranged around an image forming body to transfer and fix a toner image formed on the image forming body onto a transfer material. More particularly, the present invention relates to an image forming apparatus capable of forming an image on both sides of a transfer material.

[0002]

2. Description of the Related Art Conventionally, in double-sided image formation, an image on one side formed on an image forming body is transferred and fixed on a transfer material, and this is temporarily stored in a double-sided reversal feeding device and formed again. A method has been adopted in which a transfer material is fed from a two-sided reversing feed device in synchronization with an image formed on a body, and an image on the other surface is transferred and fixed onto the transfer material.

In this double-sided image forming apparatus, as described above,
The transfer of the transfer material, such as feeding to the two-sided reversing feed device or passing through the fixing device twice, is performed, so that the reliability of transfer of the transfer material is low, causing jams and wrinkles of the transfer material. .

On the other hand, JP-B-49-37538, JP-B-54-28740, and JP-A-1-444.
No. 57 and Japanese Unexamined Patent Publication No. 4-214576,
There has been proposed an image forming apparatus that forms a toner image on both surfaces of a transfer material using a first image holding unit and a second image holding unit, and then performs fixing once.

Further, the inventors of the present invention arranged a toner image forming means including a charging means, an image writing means, a developing means, etc. around a photosensitive drum (image forming body) and formed the image on the photosensitive drum. A two-sided image forming apparatus and an image forming method for transferring a toner image to a belt-shaped intermediate transfer body, retransferring the toner image to a transfer material, and fixing the toner image on the transfer material by a fixing unit are disclosed in Japanese Patent Application Laid-Open No. 9-258492. Gazette and JP-A-9-2585
No. 16 and the like.

[0006]

However, in the above-described image forming apparatus, a transfer material having an unfixed toner image on both sides is conveyed to the fixing device. It is necessary to arrange the transfer material and feed the transfer material separated from the intermediate transfer member directly to the fixing device. However, when the intermediate transfer member is arranged close to the fixing device, the heat from the fixing device deforms the intermediate transfer member, and the toner image transferred on the intermediate transfer member tends to be fused and is difficult to transfer. Or the toner adheres to the intermediate transfer member. When the transfer material is separated from the intermediate transfer member, since the transfer material is electrostatically adsorbed to the intermediate transfer member, a transfer material separation means (paper separation AC static eliminator) is provided to secure the separation property. Although electrical separation is performed, there is a problem that separation failure occurs when an environment is changed or thin paper is used. For this purpose, the intermediate transfer body and the fixing device are spaced apart from each other, and a transport unit having a claw member (separating claw) and a spur member (spur) is provided between the intermediate transfer body and the fixing device. The transfer material is transported from the intermediate transfer member to the fixing device by the member, but the spur member and the claw member are arranged close to the intermediate transfer member, and the intermediate transfer is performed by the spur member and the claw member during jam processing. The problem is that the body is damaged.

[0007] Further, at the time of jam processing, there arises a problem that the transfer material is caught on the spur member and the transfer material is difficult to be removed, or the spur member is caught and damaged. Furthermore, in addition to the damage caused by the transfer material being caught on the spur member during the jam processing, there is also a problem that a finger or the like may be caught on the spur member when the user removes the transfer material, resulting in an injury.

The present invention solves the above-mentioned problems, and prevents the spur member and the claw member disposed close to the intermediate transfer member from being damaged during the jam processing, and also facilitates the removal of the transfer material. It is another object of the present invention to provide an image forming apparatus that prevents a transfer material from being damaged by being caught on a spur member, and prevents an injury due to being caught on a spur member when a user removes the transfer material.

[0009]

The object of the present invention is to transfer a toner image formed on an image forming member to a belt-shaped intermediate transfer member, and then re-transfer the toner image to a transfer material to form a toner image having the toner image. In an image forming apparatus in which a toner image on a transfer material is fixed by a fixing unit, a spur member and a claw member that are arranged close to each other and convey the transfer material to the fixing unit are integrally transferred together with the intermediate transfer body. This is achieved by an image forming apparatus, wherein the transfer material transport unit is separated from the fixing unit so as to face a surface of the transfer material having a toner image during a jam processing.

[0010]

Embodiments of the present invention will be described below. Note that the description in this column does not limit the technical scope of the claims and the meaning of terms. Also, the following assertive description in the embodiment of the present invention indicates the best mode, and does not limit the meaning of the terms of the present invention or the technical scope. In the following description of the embodiment, the surface of the transfer material on the side facing the image forming body in the transfer area is called the front surface, and the other surface of the transfer material, that is, the surface of the transfer material on the side facing the intermediate transfer body is called the back surface. The image transferred to the front surface of the transfer material is called a front image, and the image transferred to the back surface of the transfer material is called a back image.

An image forming process and each mechanism of an embodiment of the image forming apparatus of the present invention will be described with reference to FIGS. FIG. 1 is a sectional configuration view of a color image forming apparatus showing an embodiment of the image forming apparatus according to the present invention, FIG. 2 is a side sectional view of the image forming body of FIG.
FIG. 3A is a diagram illustrating a toner image forming state in the image forming apparatus according to the present invention. FIG. 3A is a diagram illustrating a toner image forming state when a back surface image formed on an image forming body is transferred onto an intermediate transfer body. FIG. 3B is a diagram showing a toner image formation state when a front surface image is formed on an image forming body in synchronization with a back side image on an intermediate transfer body, and FIG. ,
FIG. 3 is a diagram illustrating double-sided image formation on a transfer material.

In FIG. 1, reference numeral 10 denotes a photosensitive drum as an image forming body; 11, a scorotron charger as charging means for each color; 12, an exposure optical system as image writing means for each color; , 14a is an intermediate transfer belt as an intermediate transfer member, 14c is a primary transfer unit as a first transfer unit, and 14g is a second transfer unit as a second transfer unit.
A next transfer unit 150 is a paper charger which is a transfer material charging unit.
4h is a paper separating AC static eliminator as a transfer material separating means, 160
Is a separation claw 210 as a claw member and a spur 16 as a spur member
2, a transfer unit 300, a transfer material transfer unit 1,
69 is a protection member, and 17 is a fixing device as a fixing unit.

As shown in FIGS. 1 to 3, a photosensitive drum 10 as an image forming body is provided with a transparent conductive material around a cylindrical base formed of a transparent member such as optical glass or transparent acrylic resin. A photosensitive layer such as a layer, an a-Si layer or an organic photosensitive layer (OPC) is formed, and is rotated clockwise as indicated by an arrow in FIG. 1 with the conductive layer grounded.

The photosensitive drum 10, as shown in FIG.
Flange members 10a and 1 at both ends for engaging and fixing it
The gear G integrated with the flange member 10b is supported by the bearings B1 and B2 fitted to the drum shaft 30 and is rotatably supported by the drum shaft 30 erected and fixed to the apparatus main body. When driven by meshing with the drive gear, it is rotated at a constant speed in a predetermined direction.

A scorotron charger 11, which is a charging unit for each color, an exposure optical system 12, which is an image writing unit for each color, and a developing unit 13, which is a developing unit for each color, form a set of yellow (Y) ), Magenta (M), cyan (C), and black (K) are provided for the image forming process, and four sets are provided.
With respect to the 0 rotation direction, they are arranged in the order of Y, M, C, and K.

The scorotron charger 11, which is a charging means for each color, has a control grid maintained at a predetermined potential and a discharge electrode 11a composed of, for example, a sawtooth electrode, and faces the photosensitive layer of the photosensitive drum 10. And installed
The charging operation (in the present embodiment, negative charging) is performed by corona discharge having the same polarity as that of the toner.
A uniform potential is given to 0. As the discharge electrode 11a, a wire electrode or a needle electrode may be used.

Exposure optical system 1 as image writing means for each color
2 indicates that the exposure position on the photosensitive drum 10 is the photosensitive drum 1 with respect to the scorotron charger 11 for each color described above.
It is arranged inside the photoconductor drum 10 so as to be located on the downstream side in the rotation direction of 0. As shown in FIG. 2, each exposure optical system 12 has a line in which a plurality of LEDs (light emitting diodes) as light emitting elements of image exposure light arranged in the main scanning direction in parallel with the drum shaft 30 are arranged. An exposure unit composed of an exposure element 12a in the shape of a circle, a light-converging light transmitter (trade name: Selfoc lens array) 12b as an imaging element, and a lens holder 12c, which is attached to the holding member 20. . In addition to the exposure optical system 12 for each color, a transfer simultaneous exposure unit 12d and a uniform exposure unit 12e are attached to the holding member 20, and are housed integrally within the light-transmitting substrate of the photosensitive drum 10. Exposure optical system 1 for each color
2 exposes the photosensitive layer of the photosensitive drum 10 from the rear surface in accordance with image data of each color read by a separate image reading device and stored in a memory to form an electrostatic latent image on the photosensitive drum 10. As the exposure element 12a, LE
In addition to D, a plurality of light-emitting elements such as FL (phosphor light emission), EL (electroluminescence), and PL (plasma discharge) arranged in an array can be used. The emission wavelength of the image exposure light emitting element is usually in the range of 780 to 900 nm, which is highly transparent to Y, M, and C toners. For this reason, a shorter wavelength of 400 to 780 nm which does not have sufficient transparency to the color toner may be used. In FIG. 2, WA is a lead wire from a light emitting element (LED) for image exposure light.

The developing device 13 as a developing means for each color keeps a predetermined gap with respect to the peripheral surface of the photosensitive drum 10 and rotates in a forward direction with respect to the rotating direction of the photosensitive drum 10, for example, 0.5 to 1 mm in thickness. And a developing casing 131 formed of a cylindrical nonmagnetic stainless steel or aluminum material having an outer diameter of 15 to 25 mm, and a developing casing 138. Inside the developing casing 138, yellow (Y) and magenta ( M), cyan (C) and black (K) one-component or two-component developers. Each developing unit 13
Is maintained in a non-contact state with the photosensitive drum 10 with a predetermined gap, for example, 100 to 500 μm, by an abutting roller (not shown), and applies a developing bias in which a DC voltage and an AC voltage are superimposed on the developing sleeve 131. By doing
Non-contact reversal development is performed to form a toner image on the photosensitive drum 10.

The intermediate transfer belt 14a is an intermediate transfer member is an endless belt having a volume resistivity of 10 ¹² ~10 ¹⁵ Ω · cm, for example modified polyimide, thermal curing polyimide, ethylene tetrafluoroethylene copolymer, polyvinylidene fluoride A 0.1 to 1.0 mm thick semiconductive film substrate in which a conductive material is dispersed in an engineering plastic such as nylon alloy is coated with a fluorine coating preferably having a thickness of 5 to 50 μm as a toner filming preventing layer. This is a seamless belt having a two-layer structure. In addition to the above, as the base of the belt, a conductive material dispersed in silicon rubber or urethane rubber or the like having a thickness of 0.5 to 2.0
mm semi-conductive rubber belts can also be used. The intermediate transfer belt 14a includes a driving roller 1 as a roller member.
4d, an earth roller 14j, a driven roller 14e, and a tension roller 14i. The driven roller 14e and the ground roller 14 are driven according to the rotation direction of the intermediate transfer belt 14a.
j, a drive roller 14d, and a tension roller 14i are provided in this order, the driven roller 14e, the ground roller 14j, and the drive roller 14d are fixedly rotated, and the tension roller 14i is movably supported by elasticity of a spring (not shown). The tension roller 14i is rotated while stretching the intermediate transfer belt 14a. The drive roller 14d, which is a roller member, is driven by the drive motor M1 (see FIG. 4).
Is rotated to drive and rotate the intermediate transfer belt 14a. The rotation of the intermediate transfer belt 14a causes the earth roller 14j, the driven roller 14e, and the tension roller 14i.
Is rotated following. The rotating intermediate transfer belt 14a
Is loosened by the tension roller 14i. Intermediate transfer belt 14 stretched around drive roller 14d
The recording paper P is separated from the intermediate transfer belt 14a at a curvature portion KT at the end of the fixing device 17 on the side of the fixing device 17a.

A primary transfer unit 14c as a first transfer unit
Is a corona discharge device provided to face the photosensitive drum 10 with the intermediate transfer belt 14a interposed therebetween, and forms a transfer area 14b between the intermediate transfer belt 14a and the photosensitive drum 10. A DC voltage having the opposite polarity (positive polarity in the present embodiment) to the toner is applied to the primary transfer device 14c.
The toner image on the photosensitive drum 10 is transferred to the intermediate transfer belt 14a.
The image is transferred onto the upper surface or the surface of the recording paper P as a transfer material.

A secondary transfer unit 14g, which is a second transfer unit, is preferably constituted by a corona discharger, and is a conductive ground roller 14 grounded with an intermediate transfer belt 14a interposed therebetween.
j, a DC voltage having a polarity opposite to that of the toner (positive polarity in the present embodiment) is applied, and the toner image on the intermediate transfer belt 14a is transferred to the back surface of the recording paper P.

The paper charger 150, which is a transfer material charging means, is preferably constituted by a corona discharger, is provided opposite to a driven roller 14e, which is grounded with the intermediate transfer belt 14a interposed, and has the same polarity as the toner (this embodiment). (In the embodiment, negative polarity) is applied, and the recording paper P is charged and attracted to the intermediate transfer belt 14a.

Paper separation AC neutralizer 1 as transfer material separating means
4h is preferably formed of a corona discharger, and is provided at an end of the intermediate transfer belt 14a on the side of the fixing device 17 as needed, facing the conductive drive roller 14d grounded with the intermediate transfer belt 14a interposed therebetween. If necessary, an AC voltage in which a DC voltage having the same polarity or opposite polarity to the toner is superimposed is applied, and the recording paper P conveyed by the intermediate transfer belt 14a is discharged and separated from the intermediate transfer belt 14a.

The transport section 160 includes a separation claw 210 as a claw member.
And a spur member 162 serving as a spur member. The spur member 162 is provided between the fixing device 17 and the curvature portion KT at the end of the intermediate transfer belt 14a on the fixing device 17 side. The transport unit 160 includes the fixing device 1
7, the intermediate transfer belt 14a is deformed, the toner image carried on the intermediate transfer belt 14a tends to be fused, and the transfer is difficult.
4a is prevented from sticking to the toner.

The separation claw 210, which is a claw member, approaches the curvature portion KT of the intermediate transfer belt 14a, and
Is fixed to the support shaft 221 at a predetermined interval, preferably 0.1 to 2.0 mm, and when the recording paper P is separated from the intermediate transfer belt 14a, the intermediate transfer belt 1
The leading end of the recording paper P, which is bent and conveyed in the direction 4a, is brought into contact with the recording paper P to assist the separation of the recording paper P.

The spur 162, which is a spur member, has a plurality of protrusions 162a (see FIG. 5) on its peripheral surface.
5 is provided rotatably. The spur 162
The recording paper P is conveyed by guiding the back side of the recording paper P to prevent disturbance of the back side toner image of the recording paper P having the toner image on both sides, and to keep the recording paper P entering the fixing device 17 in a fixed direction. The recording paper P is conveyed to the fixing device 17 in a stable manner.

The separation claw 210 and the spur 162 are connected to the transfer material conveying surface of the intermediate transfer belt 14a or its extension surface PL1.
It is disposed on the opposite side of the photosensitive drum 10 with respect to (hereinafter, referred to as a transfer material transport surface PL1). It is also possible to provide spurs 162 as spur members on both sides of the transfer material transport surface PL1.

The transfer material transport unit 300 is a unit member formed integrally with the intermediate transfer belt 14a, an intermediate transfer body cleaning device 140 described later, and a transport section 160 having a separation claw 210 and a spur 162.
The recording paper P entering the intermediate transfer belt 14a is transported to the fixing device 17.

The protection member 169 is a plate-like member provided on the side surface of the spur 162 in parallel with the recording paper P conveyance direction, and is attached to a fixing plate 168 fixed to the apparatus main body.
This prevents damage to the spur 162 and injury to the user's hand during jam clearance.

The fixing device 17 as a fixing means is composed of two roller-shaped fixing members, a fixing roller 17a having a heater therein and a pressure roller 17b.
The recording paper P is nipped at the nip T between the a and the pressure roller 17b, and the toner image on the recording paper P is fixed by applying heat and pressure.

Next, the image forming process will be described.

The photosensitive drum 10 is rotated clockwise as indicated by an arrow in FIG. 1 by starting a photosensitive member driving motor (not shown) at the start of image recording, and at the same time, is exposed to light by the charging action of a yellow (Y) scorotron charger 11. Body drum 1
Application of a potential to 0 starts.

After a potential is applied to the photosensitive drum 10, the Y exposure optical system 12 starts image writing by a first color signal, that is, an electric signal corresponding to the Y image data. An electrostatic latent image corresponding to the Y image of the original image is formed on the front surface.

The latent image is reversely developed in a non-contact state by the Y developing device 13, so that a yellow (Y) toner image is formed on the photosensitive drum 10.

Next, a potential is applied to the photosensitive drum 10 from above the Y toner image by the charging action of the magenta (M) scorotron charger 11, and the second color signal, that is, the M color signal, is applied by the M exposure optical system 12. Image writing is performed by an electric signal corresponding to the image data, and the magenta (M) toner image is superimposed on the yellow (Y) toner image by non-contact reversal development by the M developing unit 13. It is formed.

By the same process, the cyan (C) toner image corresponding to the third color signal is further superimposed by the cyan (C) scorotron charger 11, the exposure optical system 12 of C and the developing device 13 of C. The black (K) toner image corresponding to the fourth color signal is sequentially superimposed thereon by a black (K) scorotron charger 11, a K exposure optical system 12, and a K developing device 13. A superposed color toner image of four colors of yellow (Y), magenta (M), cyan (C) and black (K) is formed on the peripheral surface within one rotation of the photosensitive drum 10. .

These Y, M, C and K exposure optical systems 12
Image writing on the photosensitive layer of the photosensitive drum 10 is performed from the inside of the drum through the above-described translucent substrate. Therefore, the writing of the images corresponding to the second, third and fourth color signals is performed without any influence from the previously formed toner image, and is equivalent to the image corresponding to the first color signal. Can be formed.

The superimposed color toner image, which is the back image formed on the photosensitive drum 10 as the image forming body by the above image forming process, is transferred to the transfer area 14b.
The primary transfer unit 14c, which is a first transfer unit, collectively transfers the image onto an intermediate transfer belt 14a, which is an intermediate transfer body (FIG. 3A). At this time, uniform exposure may be performed by the simultaneous transfer exposure device 12d provided inside the photoconductor drum 10 so that good transfer is performed.

After the toner remaining on the peripheral surface of the photosensitive drum 10 after the transfer is subjected to static elimination by the photosensitive drum AC static eliminator 16, the toner is transferred to a cleaning device 19 which is an image forming body cleaning means. The toner is cleaned by a cleaning blade 19a made of a rubber material in contact with the toner, and collected by a screw 19b in a toner discharge container (not shown). Further, the peripheral surface of the photosensitive drum 10
For example, a uniform exposure device 12 before charging using a light emitting diode
The history of the photosensitive drum 10 in the previous image formation is eliminated by the exposure by e.

After the superimposed color toner image serving as the back side image is formed on the intermediate transfer belt 14a as described above, the front side image is continuously formed on the photosensitive drum 10 in the same manner as the above color image forming process. Is formed (FIG. 3B). On this occasion,
The image data is changed so that the front surface image formed on the photoconductor drum 10 becomes a mirror image with respect to the rear surface image formed on the photoconductor drum 10.

With the formation of the surface image on the photosensitive drum 10, recording paper P as a transfer material is sent out from a paper feed cassette 15 as a transfer material storage means by a feed roller 15a, and is used as a transfer material feeding means. Timing roller 1
5b, and the timing roller 15b drives the front surface image color toner image formed on the photosensitive drum 10 to synchronize with the back surface image color toner image carried on the intermediate transfer belt 14a. Transfer area 14
b. At this time, the fed recording paper P is charged to the same polarity as the toner by a paper charger 150 which is a transfer material charging means provided on the front surface side of the recording paper P, and is attracted to the intermediate transfer belt 14a to be transferred to the transfer area. 14b. By charging the paper with the same polarity as that of the toner, the toner is prevented from being attracted to the toner image on the intermediate transfer belt 14a and the toner image on the photosensitive drum 10, thereby preventing the toner image from being disturbed. In addition to the corona discharger, a paper charging brush or a paper charging roller that can abut and release the intermediate transfer belt 14a can be used as the paper charger 150.

In the transfer area 14b, a first voltage to which a voltage having a polarity opposite to that of the toner (positive in this embodiment) is applied.
The surface image on the photosensitive drum 10 is collectively transferred to the surface of the recording paper P by the primary transfer device 14c as the transfer means. At this time, the back surface image on the intermediate transfer belt 14a is not transferred to the recording paper P but exists on the intermediate transfer belt 14a. At the time of transfer by the primary transfer unit 14c, a transfer simultaneous exposure unit 12d using a light emitting diode, for example, provided inside the photosensitive drum 10 facing the transfer area 14b so that good transfer is performed. Exposure may be performed.

The recording paper P on which the color toner image has been transferred to the surface thereof is transferred to a secondary transfer unit 14g as a second transfer means to which a voltage having a polarity opposite to that of the toner (positive polarity in this embodiment) is applied. The sheet is conveyed, and the rear surface image on the peripheral surface of the intermediate transfer belt 14a is collectively transferred to the rear surface of the recording paper P by the secondary transfer device 14g (FIG. 3C).

The recording paper P on which the color toner images are formed on both sides is formed by the curvature of the curvature portion KT of the intermediate transfer belt 14a and the paper as transfer material separating means provided at the end of the intermediate transfer belt 14a as necessary. The spur 162 provided on the transport unit 160 is separated from the intermediate transfer belt 14a by the static elimination action of the separation AC neutralizer 14h and the separation claw 210 provided on the transport unit 160 at a predetermined interval from the intermediate transfer belt 14a. Fixing device 17 as fixing means through
The toner image on the recording paper P is fixed by applying heat and pressure at a nip portion T between the fixing roller 17a and the pressure roller 17b. The recording paper P on which double-sided image recording has been performed is sent upside down, and is discharged by a discharge roller 18 to a tray outside the apparatus. Further, as shown by a dashed line in FIG. 1, a switching member (not shown) may be provided at the exit of the fixing device 17 so that the sheet is discharged to a tray outside the device without turning over.

The toner remaining on the peripheral surface of the intermediate transfer belt 14a after the transfer is provided to face the driven roller 14e with the intermediate transfer belt 14a interposed therebetween, and is applied to the intermediate transfer belt 14a with the support shaft 142 as a rotation fulcrum. The intermediate transfer member is cleaned by an intermediate transfer member cleaning device 140 which is an intermediate transfer member cleaning unit having an intermediate transfer member cleaning blade 141 capable of contacting and releasing contact.

The toner remaining on the peripheral surface of the photosensitive drum 10 after the transfer is removed by a photosensitive drum AC neutralizer 16 and then cleaned by a cleaning device 19. By 12e, the history of the photosensitive drum 10 in the previous image formation is eliminated, and the next image formation cycle is started.

By using the above-described method, since the superimposed color toner images are collectively transferred, color shift of the color image on the intermediate transfer belt 14a, scattering or rubbing of the toner, and the like are less likely to occur, and the image deterioration is less likely to occur. Double-sided color image formation is performed.

Although the embodiment of the double-sided image forming apparatus has been described with reference to the color image forming apparatus, the present invention is not necessarily limited to this, and the present invention is not limited to this. The present invention is also applied to a double-sided image forming apparatus.

Further, in the above-described embodiment of the image forming apparatus, first, a toner image to be a back side image is formed on the image forming body, and is temporarily transferred onto the intermediate transfer body. Subsequently, the front side image is formed on the same image forming body. The toner image on the image forming body is formed on the surface of the transfer material, and the toner image on the intermediate transfer body is transferred on the back surface of the transfer material to obtain a double-sided image. The invention is not necessarily limited to this. For example, an image forming body (hereinafter, referred to as a first image forming body) that forms a toner image serving as a back side image and an image forming body forming a toner image serving as a front side image (Hereinafter, referred to as a second image forming body) are separately provided, and the toner image formed on the first image forming body is transferred onto the intermediate transfer body. The transfer material is supplied during the period, and the toner formed on the second image forming body is Thereby transferring an image onto the surface of the transfer material, and is applied to an image forming apparatus to obtain a double-sided image by transferring the toner image on the intermediate transfer member to the back surface of the transfer material.

Further, in the image forming apparatus of the present invention,
In addition to the double-sided image formation in which an image is formed on both sides of the transfer material as described in the above-described embodiment, one-sided image formation in which an image is formed only on one side of only the front surface or the back surface of the transfer material may be performed. .

Next, a transfer section and an intermediate transfer member having a claw member and a spur member, and a transfer material transfer unit formed by the transfer section and the intermediate transfer member will be described with reference to FIGS. FIG. 4 is a view showing a transfer material transfer unit formed by a transfer section having a claw member and a spur member and an intermediate transfer body, and FIG. 5 is a perspective view of a main part of FIG.

The rotation of the drive motor M1 drives and rotates the drive roller 14d, which is a roller member.
The intermediate transfer belt 14a is rotated counterclockwise as shown by the arrow in FIG.
The recording paper P having toner images on both sides is conveyed with the rotation of. The recording paper P is fixed to the fixing device 1 of the intermediate transfer belt 14a.
At the curvature portion KT provided at the end on the 7th side, the toner image is separated from the intermediate transfer belt 14a and conveyed to the fixing device 17 through the conveyance section 160. In the conveyance section 160, the separation claw 210 as a claw member and the spur 162 as a spur member are respectively arranged in a direction perpendicular to the conveyance direction of the recording paper P, that is, the longitudinal direction of the fixing device 17 in order from the upstream side in the conveyance direction of the recording paper P The transfer material transport surface of the intermediate transfer belt 14a or its extension surface PL1 (transfer material transport surface PL
In contrast to 1), it is disposed on the opposite side of the photosensitive drum 10.
The separation claw 210 is provided near the curvature portion KT at the end of the intermediate transfer belt 14a on the fixing device 17 side.
The distance between the ten toes 211a and the rotation center of the spur 162 in the front row of the recording paper P in the conveying direction is about 5 mm to 30 mm, and the distance between the rotation centers of the spurs 162 is 10 mm to 50 mm.
mm, the rotation center of the spur 162 in the last row and the fixing device 1
7, the distance from the position where the recording paper P enters (the entrance of the nip portion T) is about 20 mm to 60 mm.

The separation claw 210 is, for example, a rod-shaped support shaft 22.
1 is fixed at a predetermined position, the both sides of the separation claw 210 are stopped by the E-ring E, and the support shaft 2 is
21. The support shaft 221 is fixed to the holders 222a and 222b at both ends attached to the transport unit housing 161 on the upstream side in the transport direction of the recording paper P, and the separation claw 210 is in the direction orthogonal to the transport direction of the recording paper P, that is, the fixing device 17.
Are arranged in parallel in the longitudinal direction. Separation claw 210
Denotes the toner image receiving member 14a with the support shaft 221 as the center of rotation.
A contact state and a release state. The separation claw 210 is provided with a claw portion 211 for separating the recording paper P, and separates the recording paper P by the toe portion 211a of the claw portion 211 in a contact state with the toner image receiver 14a. As described above, before separation, a method for improving the separability is provided by providing a paper discharging mechanism using a corona discharger such as the paper separating AC discharger 14h as the above-described transfer material separating means as necessary. However, since problems such as rough surface images due to the discharge and poor transfer due to interference with the back surface transfer discharge occur, in the present embodiment, the toner image receiver 14a is stretched without using the paper separation AC neutralizer 14h. Drive roller 14
Curvature separation by d is preferably used.

The spur 162 has a rotation support shaft 165 provided integrally with the spur 162 inserted into a hole of a semicircular stop 163 b opposite to the guide surface 163 a of the transport guide member 163, and the rotation support shaft 165 is provided. Is stopped by an E-ring E, and is rotatably attached to the conveyance guide member 163. A plurality of transport guide members 163 to which the spurs 162 are attached are attached to predetermined positions of the transport unit housing 161 to configure the transport unit 160. A plurality of spurs 162 are provided as a set of spurs H1, H2 in a direction orthogonal to the transport direction of the recording paper P. At least one set of spurs is provided.

Frame 14 for holding intermediate transfer belt 14a
k and the transport unit housing 161 are connected to the coupling members 223a, 223a at both ends.
The transfer material transport unit 300 is formed by combining the intermediate transfer belt 14a and the transport unit 160 having the separation claw 210 and the spur 162 by, for example, screws. Further, a wavy or plate-like protection member 169 is provided on the side surface of each spur 162 in parallel with the transport direction of the recording paper P.
Is provided.

As the separation claw 210, a resin molded member using, for example, Teflon, polyimide, polycarbonate resin, or the like is used. The separation claw 210 is provided with a claw portion 211. For example, 0.1 to 2.0 mm with the intermediate transfer belt 14a
The toe portion 211a of the claw portion 211 is disposed at a predetermined interval, and the tip of the recording paper P is separated by the toe portion 211a.

The spur 162 has a thickness of 0.05 to 0.5 mm obtained by etching a metal plate such as a stainless steel plate or a copper plate.
With an outer diameter of 5 to 30 mm, a thickness of 0.5 to 2.0 mm,
A member made of a resin member having an outer diameter of 5 to 30 mm is used, and is made of a polygonal member having a plurality of sharp projections 162a at its tip, for example, a hexagonal or octagonal plate-like member.

The recording paper P separated by the separation claw 210 is scooped by the spur 162 at the leading end of the recording paper P and sent to the spur 162. The spur 162 guides the recording paper P by guiding the back side of the recording paper P. The recording paper P is conveyed to the fixing device 17 while preventing the rear toner image of the recording paper P having the toner image on the rear surface from being disturbed, and keeping the entering direction to the fixing device 17 constant.

As described above, the advancing direction of the leading end of the recording sheet P after contact with the separation claw 210 is unstable. However, by providing two rows of spur members, the advancing direction of the leading end of the recording sheet P can be improved. Can be made substantially constant. In other words, the role of each spur member is different, and the spur 162 which is the spur member of the spur set H1 of the first row in the front row of the recording paper P in the conveying direction.
Plays the role of scooping up the leading end of the recording paper P, and the spur 162 of the spur set H2 in the second row in the last row determines the traveling direction of the leading end of the recording paper P, and Serves as a guide.

When the separating claw 210 or the spur 162 is a metal plate, it may be grounded through a high resistance body of 10 ⁸ to 10 ¹⁴ Ω via a supporting shaft 221 or a rotating supporting shaft 165 formed of a metal member. preferable. Separation claw 210 and spur 16
2 is grounded through a high-resistance body, so that the separation claw 2
It is possible to prevent the toner from accumulating on the spur 10 or the spur 162 or to adhere to the toner due to the image force, thereby preventing the toner image from being disturbed. In addition, the separating claw 210 and the spur 162 made of a metal plate are floated, or a voltage having the same polarity as that of the toner (in this embodiment, a negative polarity) is applied to these metal plates to prevent the toner from adhering. It is also possible to prevent disturbance. In addition, by using an insulating member such as an insulating resin member for the separation claw 210 and the spur 162, similarly to the above-described floating, the charge accumulation of the separation claw 210 and the spur 162 and toner adhesion due to a mirror image force are prevented, It is possible to prevent disturbance of the toner image. It is preferable that both the claw member and the spur member are electrically floating or installed via a high-resistance member.

Guide surface 163a of transport guide member 163
Is provided on the transfer material transport plane PL1 side (upper side) with respect to the rotation center of the spur 162. Accordingly, even when the leading end of the recording paper P separated from the intermediate transfer belt 14a by the separation claw 210 and conveyed to the spur 162 contacts the guide surface 163a, the spur 16 is scooped up by the guide surface 163a.
2, the spur 162 is driven and rotated while the projection 162a of the spur 162 contacts or pierces the recording paper P,
The recording paper P is conveyed to the fixing device 17 without the toner image being rubbed.

When the recording paper P conveyed by the intermediate transfer belt 14a is separated from the intermediate transfer belt 14a at the curvature KT at the end of the intermediate transfer belt 14a, a curvature KT at the end of the intermediate transfer belt 14a is formed. Drive roller 1
The radius of curvature of 4d is preferably 15 mm or less, more preferably 10 mm or less. The curvature radius of the intermediate transfer belt 14a is set to 15 mm or less, and the paper separation AC static eliminator 14h, which is a transfer material separating unit, is provided opposite to the end of the intermediate transfer belt 14a as in the present embodiment. A
The separation of the recording paper P is performed stably by the static elimination action of the C static eliminator 14h and the separation claw 210 as auxiliary separation means, and the movement of the recording paper P to the transport unit 160 is also performed stably. When the radius of curvature is set to 10 mm or less, it is not necessary to provide the paper separating AC static eliminator 14h, and the recording paper P is separated from the intermediate transfer belt 14a by the curvature at the end of the intermediate transfer belt 14a and the separation claw 210. Performed in a stable manner,
The movement of the recording paper P to the transport unit 160 is also performed stably.

As described above, by integrating the intermediate transfer member and the transfer portion having the claw member and the spur member as a transfer material transfer unit, a spur member disposed close to the intermediate transfer member during jam processing can be provided. Damage to the intermediate transfer member by the claw member is prevented.

One example of the separation of the transfer material transport unit from the fixing means will be described with reference to FIG. 6 and FIGS. 4 and 5 described above.

At the time of jam clearance, the transfer material transport unit 300 is separated from the fixing device 17 by, for example, rotation of a lever 301 provided in the apparatus main body and in contact with a frame 14k (not shown in FIG. 6) of the intermediate transfer belt 14a. The transfer material transport unit 300 abuts against the stopper 302 and is locked.

The driven roller 1 moves with respect to the transfer material transport surface PL1.
With the rotation axis B provided at the center of 4e as a rotation support axis, the tip end (spur member side) of the transfer material transport unit 300 is opened (downward) on the opposite side to the photosensitive drum 10 indicated by the solid arrow in FIG. The transfer material transport unit 300 from the fixing device 17.
Apart.

The separation of the transfer material transport unit makes it easy to remove the transfer material during jam processing, and prevents the transfer material from being damaged by being caught on the spur member.

Further, when the transfer material conveying unit 300 abuts against the stopper 302, the spur member 162
5 and 6, the protection member 169 is moved in a direction indicated by a solid arrow.
Of the spur 162
62a is lowered to a position indicated by a dotted line lower than the upper end 169a of the protection member 169.

Regardless of whether the transfer material transport unit 300 is separated or not, as shown in FIG. 5, the protection member 169 is not fixedly provided on the apparatus main body, but the protection member 169 can be moved to protect the transfer member during jam processing. The upper end 169a of the member 169 may be moved to a position higher than the protrusion 162a of the spur 162, as indicated by a dashed line in FIG.

As described above, the projection of the spur member is covered with the protective member during the jam processing, so that the transfer material is prevented from being damaged due to being caught on the spur member and the spur member when the user removes the transfer material. Injuries of fingers and the like due to being caught on the surface are prevented.

Another example of the separation of the transfer material conveying unit from the image forming body will be described with reference to FIG. 7 and FIGS. 4 and 5 described above.

At the time of jam clearance, the transfer material conveying unit 300 is exposed to the frame support member 301b provided in the apparatus main body and in contact with the frame 14k (not shown in FIG. 7) of the intermediate transfer belt 14a, for example, by rotating the lever 301a. Body drum 10
Separate more parallel. The transfer material transport unit 300 abuts against the stoppers 302a and 302b and is locked.

The transfer material transport unit 300 is opened (downward) in parallel with the transfer material transport surface PL1 on the opposite side of the photosensitive drum 10 indicated by the solid line arrow in FIG.
The transfer material transport unit 300 is further separated.

The separation of the transfer material transport unit facilitates the removal of the transfer material during jam clearance and prevents the transfer material from being damaged by being caught on the spur member.

Further, when the transfer material transport unit 300 abuts against the stoppers 302a and 302b, the spur member 162 moves along the side surface of the protection member 169 in the direction shown by the solid arrows in FIGS. And spurs 16
The second protrusion 162a is the upper end 169a of the protection member 169.
Lower than the position shown by the dotted line.

Regardless of whether the transfer material transport unit 300 is separated or not, as shown in FIG. 5, the protective member 169 is not fixedly provided on the apparatus main body, but the protective member 169 can be moved, and the protective member 169 can be protected during jam processing. The upper end 169a of the member 169 may be moved to a position higher than the protrusion 162a of the spur 162, as indicated by a dashed line in FIG.

As described above, the projection of the spur member is covered with the protective member during the jam processing, so that the transfer material is prevented from being damaged by being caught on the spur member and the spur member when the user removes the transfer material. Injuries of fingers and the like due to being caught on the surface are prevented.

[0078]

According to the first to third aspects of the present invention, the intermediate transfer member and the transfer portion having the claw member and the spur member are integrated as a transfer material transfer unit, so that the intermediate transfer member and the intermediate transfer member can be combined with each other during jam processing. The intermediate transfer body is prevented from being damaged by the spur member and the claw member arranged close to each other, and the separation of the transfer material transport unit makes it easy to remove the transfer material by being caught on the spur member during jam processing. It is possible to prevent the transfer material from being damaged by being caught on the spur member.

According to the fourth aspect of the present invention, the spur member is covered with the protection member, so that when the jam is cleared, the transfer material is prevented from being damaged due to the spur member being caught on the spur member. Is prevented from being caught on the spur member.

[Brief description of the drawings]

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

FIG. 2 is a side sectional view of the image forming body of FIG. 1;

FIG. 3 is a diagram illustrating a toner image forming state in the image forming apparatus according to the present invention.

FIG. 4 is a diagram illustrating a transfer material transport unit formed by a transport unit having a claw member and a spur member and an intermediate transfer member.

FIG. 5 is a perspective view of a main part of FIG.

FIG. 6 is a diagram illustrating an example of a separation of a transfer material transport unit from a fixing unit.

FIG. 7 is a diagram illustrating another example of the separation of the transfer material transport unit from the image forming body.

[Explanation of symbols]

 Reference Signs List 10 photoconductor drum 11 scorotron charger 12 exposure optical system 13 developing device 14a intermediate transfer belt 14c primary transfer device 14g secondary transfer device 17 fixing device 160 transport unit 162 spur 169 protective member 210 separation claw 300 transfer material transport unit B times Moving axis P Recording paper

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI G03G 15/01 114 G03G 15/01 114A 15/20 101 15/20 101 (72) Inventor Kuki Nagase 2970 Ishikawacho, Hachioji-shi, Tokyo Address Konica Co., Ltd.

Claims (4)

[Claims] 1. A toner image formed on an image forming body is transferred to a belt-shaped intermediate transfer body, and then the toner image is re-transferred to a transfer material, and a toner image having the toner image on the transfer material is fixed. A spur member and a claw member, which are arranged close to each other and convey the transfer material to the fixing unit, together with the intermediate transfer member, are formed as an integral transfer material conveyance unit, An image forming apparatus, wherein the transfer material transport unit is separated from the fixing unit so as to face a surface of the transfer material having a toner image. 2. The image forming apparatus according to claim 1, wherein the transfer material conveying unit is separated from the fixing unit about a rotation axis. 3. The image forming apparatus according to claim 1, wherein the transfer material transport unit is separated from the image forming body in parallel. 4. The image forming apparatus according to claim 1, wherein a protective member projects from the spur member at the time of separation.