JPH1165178A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of preventing a second image carrying means from being affected by heat from a fixing means, satisfactorily separating a transfer material from the second image carrying means and transporting the transfer material to the fixing means without disturbing a rear side toner image (without rubbing). SOLUTION: This image forming device is constituted so as to provide a curvature part KT separating a transfer material in an end part on the fixing means side of a second image carrying means, to provide a pawl member 210, a first spur member 172 and a second spur member 162 in order thereof, between the curvature part KT and the fixing means, to scrape up the leading end part of the transfer material separated from the second image carrying means by the first spur member 172 after being brought into contact with the pawl member 210, to approximately make the entering direction constant into the fixing means by the first and second spur members 172 and 162 and to make it enter into the fixing means so that the rear side of the transfer material is not brought into contact with the pawl member 210, after the leading end part of the transfer material is scraped up by the first spur member 172.

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 carrier to transfer and fix a toner image formed on the image carrier 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 forming a double-sided image, an image on one side formed on an image carrier is transferred and fixed onto a transfer material, and this is temporarily stored in a double-sided reversal feeding device, and the image is re-supported. 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 and JP-B-54-28740, and JP-A-1-44457.
Japanese Patent Application Laid-Open No. 4-214576 discloses a method in which a toner image is formed on both surfaces of a transfer material by using a first image bearing unit and a second image bearing unit, and then fixed once. ing.

Further, the present inventors have arranged a plurality of sets of toner image forming means including a charging means, an image writing means, a developing means, etc. around a photosensitive drum (first image carrying means). The superimposed color toner image formed on the drum is once collectively transferred to a belt-shaped toner image receiver (second image carrying means) by the first transfer means, and then the superimposed color toner image is again transferred onto the photosensitive drum. A toner image is formed, and a transfer material fed at the same time as the toner image on the photosensitive drum and the toner image on the toner image receiver is charged by a transfer material charging unit and adsorbed on the toner image receiver, The toner image on the photosensitive drum is transferred to both surfaces of the transfer material conveyed by the toner image receiver by a first transfer unit as a front image, and the toner image on the toner image receiver is transferred to a second surface by a first transfer unit. Turn After the transfer by the means, the curvature of the roller member provided on the side of the fixing device (fixing means) for stretching the toner image receiver and the transfer material from the toner image receiver by static elimination by the transfer material separating means provided as necessary An image forming apparatus and an image forming method for forming a two-sided color image by separating the toner image on a transfer material and fixing the toner image on the transfer material by a fixing device are being studied.

[0006]

However, in the double-sided image forming apparatus using the belt-shaped toner image receiver as described above, the transfer material immediately after receiving the transfer of the back side toner image by the second transfer means is a toner. Since the toner is strongly electrostatically attracted to the image receiving member, it is very difficult to separate the transfer material from the toner image receiving member. For this reason, in order to ensure the separation property of the transfer material, the curvature separation of the roller member at the end on the fixing device side on which the toner image receiving member is stretched is reduced, or the transfer material separation means (paper separation means) is used. An AC static eliminator is provided to perform electrostatic separation, but a problem arises in that separation failure occurs when the environment changes or when thin paper is used.

In the above-described image forming apparatus and image forming method, a transfer material having an unfixed toner image on both sides is conveyed to a fixing device. Then, the transfer material separated from the toner image receiver is directly sent to the fixing device. However, if the toner image receiver is arranged close to the fixing device, the heat from the fixing device may cause the toner image receiver to be deformed or the toner image transferred onto the toner image receiver to be slightly fused. Or the toner is fixed on the toner image receiver. Also, since the transfer of the transfer material separated from the toner image receiver according to the type of the transfer material is unevenly conveyed, the toner image receiver having an unfixed toner image on both surfaces (also on the back surface) is used. When the separated transfer material is transported to the fixing device,
There is also a problem that the toner image on the back surface is disturbed (rubbed) and a good double-sided image cannot be formed.

The present invention solves the above-mentioned problems, and the heat from the fixing means causes the second image bearing means to be deformed,
The toner image on the image carrying means is not likely to be transferred due to a tendency to fuse, and the toner is not fixed on the second image carrying means. It is an object of the present invention to provide an image forming apparatus that separates toner images more favorably and stably conveys a toner image on a back surface to a fixing unit without disturbing (rubbing).

[0009]

An object of the present invention is to provide a first image carrying means for carrying a toner image formed by a toner image forming means, and a transfer of the toner image carried by the first image carrying means. A second image carrying means for carrying the transferred toner image on the surface and transporting a transfer material; and transferring the toner image carried by the first image carrying means to the second image carrying means or the second image carrying means. A first transfer unit that transfers the toner image carried by the second image holding unit to the front surface of the transfer material; a second transfer unit that transfers the toner image carried by the second image carrying unit to the back surface of the transfer material; A fixing unit for fixing the toner image, wherein a curvature portion for separating the transfer material from the second image bearing unit is provided at an end of the second image bearing unit on the fixing unit side. , Close to the curvature portion, A first claw member which is rotatable and has a plurality of protrusions on its peripheral surface on the downstream side in the transport direction of the transfer material in the vicinity of the claw member to guide the back surface side of the transfer material; And a second spur member rotatably provided between the first spur member and the fixing means and having a plurality of protrusions on the peripheral surface for guiding the back side of the transfer material. A spur member is provided, and a tip end of the transfer material separated from the second image bearing means is brought into contact with the claw member and then scooped up by the first spur member, and the first spur member and the first spur member are scooped up. After making the direction of entry into the fixing means substantially constant by the second spur member and entering the fixing means, and scooping up the leading end of the transfer material by the first spur member, the transfer material of the transfer material is removed. Prevent the back side from contacting the claw member Is achieved by an image forming apparatus, wherein the door (the first invention).

The above object is also achieved by a first image carrying means for carrying a toner image formed by a toner image forming means,
The toner image carried by the first image carrier is transferred, and the transferred toner image is carried on the surface.
A second image carrying means for conveying a transfer material, a first transfer means for transferring a toner image carried on the first image carrying means to the second image carrying means or a surface of the transfer material, An image forming apparatus comprising: a second transfer unit configured to transfer a toner image carried by the second image holding unit to a back surface of the transfer material; and a fixing unit configured to fix the toner image transferred to the transfer material. A claw member and a first spur member rotatable and having a plurality of protrusions on a peripheral surface thereof, in order from an upstream side in a conveying direction of the transfer material, between the second image bearing unit and the fixing unit. And a plurality of second spur members that are rotatable and have a plurality of protrusions on the peripheral surface are respectively provided in a direction orthogonal to the transfer direction of the transfer material, and are transferred by the second image bearing unit. Closest to the extension surface of the transfer surface of the transfer material and the claw member. A release H1 (mm), the closest distance between said first spur member and the extension surface H2 (mm), the closest distance between the said extension surface second spur members H3 (m
m), the image forming apparatus is characterized in that H3 ≦ H2 <H1 (second invention).

The above object is also achieved by a first image carrying means for carrying a toner image formed by a toner image forming means,
The toner image carried by the first image carrier is transferred, and the transferred toner image is carried on the surface.
A second image carrying means for conveying a transfer material, a first transfer means for transferring a toner image carried on the first image carrying means to the second image carrying means or a surface of the transfer material, An image forming apparatus comprising: a second transfer unit configured to transfer a toner image carried by the second image holding unit to a back surface of the transfer material; and a fixing unit configured to fix the toner image transferred to the transfer material. A claw member and a first spur member rotatable and having a plurality of protrusions on a peripheral surface thereof, in order from an upstream side in a conveying direction of the transfer material, between the second image bearing unit and the fixing unit. And a plurality of second spur members that are rotatable and have a plurality of protrusions on the peripheral surface, each of which is provided in a direction orthogonal to the transfer direction of the transfer material, and a second spur member is provided on the peripheral surface of the first spur member. The radius of curvature is r1 (mm), and the radius of curvature of the second spur member is r2. When the mm), it is achieved by an image forming apparatus characterized by the r1 <r2 (third invention).

The above object is also achieved by a first image holding means for holding a toner image formed by a toner image forming means,
The toner image carried by the first image carrier is transferred, and the transferred toner image is carried on the surface.
A second image carrying means for conveying a transfer material, a first transfer means for transferring a toner image carried on the first image carrying means to the second image carrying means or a surface of the transfer material, An image forming apparatus comprising: a second transfer unit configured to transfer a toner image carried by the second image holding unit to a back surface of the transfer material; and a fixing unit configured to fix the toner image transferred to the transfer material. A claw member and a first spur member rotatable and having a plurality of protrusions on a peripheral surface thereof, in order from an upstream side in a conveying direction of the transfer material, between the second image bearing unit and the fixing unit. And a plurality of second spur members that are rotatable and have a plurality of protrusions on the peripheral surface are provided in a direction orthogonal to the transfer direction of the transfer material, and a plurality of second spur members are provided adjacent to the first spur member. The interval between the parts is P1 (mm), adjacent to the second spur member When the distance raised portion and P2 (mm), it is achieved by an image forming apparatus characterized by a P1 <P2 (fourth invention).

The above object is also achieved by a first image holding means for holding a toner image formed by a toner image forming means,
The toner image carried by the first image carrier is transferred, and the transferred toner image is carried on the surface.
A second image carrying means for conveying a transfer material, a first transfer means for transferring a toner image carried on the first image carrying means to the second image carrying means or a surface of the transfer material, An image forming apparatus comprising: a second transfer unit configured to transfer a toner image carried by the second image holding unit to a back surface of the transfer material; and a fixing unit configured to fix the toner image transferred to the transfer material. A claw member and a first spur member rotatable and having a plurality of protrusions on a peripheral surface thereof, in order from an upstream side in a conveying direction of the transfer material, between the second image bearing unit and the fixing unit. And a plurality of second spur members that are rotatable and have a plurality of protrusions on the peripheral surface are respectively provided in a direction orthogonal to the transfer direction of the transfer material, and are transferred by the second image bearing unit. A center portion of the claw member perpendicular to the transfer surface of the transfer material Is the closest distance between a virtual cross section that crosses the transfer material transport direction and the peripheral surface of the first spur member closest to the cross section, d1 (mm), and the closest distance between the cross section and the cross section When the closest distance from the peripheral surface of the second spur member is d2 (mm), d1 <d2 is satisfied.
Invention).

[0014] The above object is also achieved by a first image carrying means for carrying a toner image formed by a toner image forming means,
The toner image carried by the first image carrier is transferred, and the transferred toner image is carried on the surface.
A second image carrying means for conveying a transfer material, a first transfer means for transferring a toner image carried on the first image carrying means to the second image carrying means or a surface of the transfer material, An image forming apparatus comprising: a second transfer unit configured to transfer a toner image carried by the second image holding unit to a back surface of the transfer material; and a fixing unit configured to fix the toner image transferred to the transfer material. A claw member and a first spur member rotatable and having a plurality of protrusions on a peripheral surface thereof, in order from an upstream side in a conveying direction of the transfer material, between the second image bearing unit and the fixing unit. And a plurality of second spur members that are rotatable and have a plurality of protrusions on the peripheral surface are respectively provided in a direction orthogonal to the transfer direction of the transfer material, and a distance between the claw members farthest apart is set. W1 (mm), the distance between the farthest first spur members is W (Mm), the distance between the second spur member farthest when the W3 (mm), W1 ≦ W2
<W3 is achieved by an image forming apparatus (sixth invention).

Further, the above object is to provide a first image carrying means for carrying a toner image formed by a toner image forming means,
The toner image carried by the first image carrier is transferred, and the transferred toner image is carried on the surface.
A second image carrying means for conveying a transfer material, a first transfer means for transferring a toner image carried on the first image carrying means to the second image carrying means or a surface of the transfer material, An image forming apparatus comprising: a second transfer unit configured to transfer a toner image carried by the second image holding unit to a back surface of the transfer material; and a fixing unit configured to fix the toner image transferred to the transfer material. A claw member and a first spur member rotatable and having a plurality of protrusions on a peripheral surface thereof, in order from an upstream side in a conveying direction of the transfer material, between the second image bearing unit and the fixing unit. And a plurality of second spur members that are rotatable and have a plurality of protrusions on the peripheral surface are respectively provided in a direction orthogonal to the transfer direction of the transfer material, and the number of the claw members is N1, The number of the first spur members is N2, and the number of the second spur members is N When a, N1 ≦ N2 and N1
This is achieved by an image forming apparatus, wherein + 1 ≦ N3 (seventh invention).

The above object is also achieved by a first image carrying means for carrying a toner image formed by a toner image forming means,
The toner image carried by the first image carrier is transferred, and the transferred toner image is carried on the surface.
A second image carrying means for conveying a transfer material, a first transfer means for transferring a toner image carried on the first image carrying means to the second image carrying means or a surface of the transfer material, An image forming apparatus comprising: a second transfer unit configured to transfer a toner image carried by the second image holding unit to a back surface of the transfer material; and a fixing unit configured to fix the toner image transferred to the transfer material. A claw member and a first spur member rotatable and having a plurality of protrusions on a peripheral surface thereof, in order from an upstream side in a conveying direction of the transfer material, between the second image bearing unit and the fixing unit. And a plurality of second spur members that are rotatable and have a plurality of protrusions on the peripheral surface, each of which is provided in a direction orthogonal to the transfer direction of the transfer material. The back side of the transfer material can be guided between It is achieved by an image forming apparatus characterized by providing a conveying guide member extending in the conveying direction of the timber (eighth invention).

The above object is also achieved by a first image carrying means for carrying a toner image formed by a toner image forming means,
The toner image carried by the first image carrier is transferred, and the transferred toner image is carried on the surface.
A second image carrying means for conveying a transfer material, a first transfer means for transferring a toner image carried on the first image carrying means to the second image carrying means or a surface of the transfer material, An image forming apparatus comprising: a second transfer unit configured to transfer a toner image carried by the second image holding unit to a back surface of the transfer material; and a fixing unit configured to fix the toner image transferred to the transfer material. A claw member and a first spur member rotatable and having a plurality of protrusions on a peripheral surface thereof, in order from an upstream side in a conveying direction of the transfer material, between the second image bearing unit and the fixing unit. And a plurality of second spur members that are rotatable and have a plurality of protrusions on a peripheral surface thereof are provided in a direction perpendicular to a transfer direction of the transfer material, respectively, and the claw member and the first spur member are provided. And the first spur member supporting member for supporting To, the transfer material of the pawl member is a surface of the side contacting is achieved by an image forming apparatus, characterized in that the concave curved on the back side of the transfer material (ninth invention).

[0018]

Embodiments of the present invention will be described below. The description in this section does not limit the technical scope of the claims and the meaning of the terms. The assertive description below shows the best mode, and limits the technical scope of the present invention and the meaning of the terms. It does not do. In the following description of the embodiment, in the transfer area, the surface of the transfer material on the side facing the first image bearing means is the surface, and the other surface of the transfer material, ie, the transfer material on the side facing the second image bearing means 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.

FIG. 1 shows an image forming process and each mechanism of an embodiment of an image forming apparatus common to each invention of the present invention.
This will be described with reference to FIG. FIG. 1 is a sectional 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 first image bearing means of FIG. FIG. 3 is a diagram showing a toner image forming state in the image forming apparatus according to the present invention.
(A) shows the image of the back side formed on the first image carrier
FIG. 3B is a diagram showing a toner image formation state when the toner image is transferred onto the image bearing means. FIG. 3B is a view showing the front image on the first image bearing means in synchronization with the back image on the second image bearing means. FIG. 3C is a diagram showing a toner image forming state when forming a toner image, and FIG.
FIG. 4 is a diagram showing double-sided image formation on a transfer material.
FIG. 5 is a diagram showing a claw member, a first spur member, and a second spur member, and FIG. 5 is a perspective view of a main part of FIG.

In FIG. 1, reference numeral 10 denotes a photosensitive drum as first image bearing means, 11 a scorotron charger as charging means for each color, 12 an exposure optical system as image writing means for each color, 13 Denotes a developing device which is a developing means for each color;
Reference numeral a denotes a toner image receiving body as a second image carrying means, 14c a primary transfer unit as a first transfer unit, 14g a secondary transfer unit as a second transfer unit, and 150 a transfer material charging unit. A certain paper charger, 14h is a paper separating AC static eliminator as a transfer material separating means, 160 is a separation claw 210 as a claw member, a front spur 172 as a first spur member, and a rear spur 162 as a second spur member. And a fixing device 17 serving as a fixing unit.

Photosensitive drum 10 as first image bearing means
Is formed by forming a photosensitive layer such as a transparent conductive layer, an a-Si layer, or an organic photosensitive layer (OPC) on the outer periphery of a cylindrical substrate formed of a transparent member such as optical glass or transparent acrylic resin. And rotated clockwise as indicated by the 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, an element in which a plurality of light-emitting elements such as FL (phosphor light emission), EL (electroluminescence), and PL (plasma discharge) are 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 light emitting element (L
ED).

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 the forward direction of the rotating direction of the photosensitive drum 10, for example, 0.5 to 1 mm in thickness. , A developing sleeve 131 formed of a non-magnetic stainless steel or aluminum material having a cylindrical outer diameter of 15 to 25 mm, and a developing casing 138. Yellow (Y), magenta (M), cyan (C), It contains a black (K) one-component or two-component developer. Each of the developing devices 13 is provided with a predetermined gap, for example, 100 to 500 μm, from the photosensitive drum 10 by an abutting roller (not shown).
Is applied, and a non-contact reversal development is performed by applying a developing bias in which a DC voltage and an AC voltage are superimposed on the developing sleeve 131, and a toner image is formed on the photosensitive drum 10. Form.

Toner image receiver 1 as second image bearing means
4a is an endless belt having a volume resistivity of 10 ¹² to 10 ¹⁵ Ω · cm, for example, modified polyimide, thermosetting polyimide,
Conductive material dispersed in engineering plastics such as ethylene tetrafluoroethylene copolymer, polyvinylidene fluoride, nylon alloy, etc., thickness 0.1-0.5m
A seamless belt having a two-layer structure in which a fluorine coating having a thickness of 5 to 50 μm is preferably formed on the outside of a semiconductive film substrate having a thickness of 5 m as a toner filming preventing layer. As a base material of the belt, in addition to the above, a conductive material dispersed in silicon rubber or urethane rubber or the like has a thickness of 0.5 to 0.5.
A 2.0 mm semiconductive rubber belt can also be used. The toner image receiver 14a is stretched in contact with a driving roller 14d, a driven roller 14e, a guide roller 14f, and a tension roller 14i, which are roller members, and is rotated in a counterclockwise direction indicated by an arrow in FIG. Toner image receiver 1
4a, the driven roller 14e, the driving roller 14d, the tension roller 14i, the guide roller 14f
, A driven roller 14e and a driving roller 14d.
The guide roller 14f is fixedly rotated, and the tension roller 14i is movably supported by an elastic force such as a spring (not shown), and is rotated while stretching the toner image receiver 14a. When driven by the drive motor M1 (see FIG. 4), the drive roller 14d, which is a roller member, is rotated, and the toner image receiver 14a is driven and rotated. Toner image receiver 14a
, The driven roller 14e, the guide roller 14f and the tension roller 14i are driven and rotated. Belt slack of the rotating toner image receiver 14a is tensioned by the tension roller 14i. The recording paper P is separated from the toner image receiver 14a at a curvature portion KT at the end of the fixing device 17 side of the toner image receiver 14a stretched over the driving roller 14d.

A primary transfer unit 14c as a first transfer unit
Is a corona discharger provided opposite the photosensitive drum 10 with the toner image receiver 14a interposed therebetween, and forms a transfer area 14b between the toner image receiver 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 toner image receiving member 14a.
The image is transferred onto the upper surface or the surface of the recording paper P as a transfer material.

The secondary transfer device 14g as the second transfer means is preferably constituted by a corona discharger, and is a conductive drive roller 14d grounded with the toner image receiver 14a interposed therebetween.
And a DC voltage having a polarity opposite to that of the toner (positive polarity in this embodiment) is applied to transfer the toner image on the toner image receiver 14 a 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 across the toner image receiver 14a, and has the same polarity as the toner. A DC voltage (in the embodiment, a negative polarity) is applied, and the recording paper P is charged and attracted to the toner image receiver 14a.

Paper separation AC static eliminator 1 as transfer material separating means
4h is preferably constituted by a corona discharger, and is provided at the end of the toner image receiving member 14a on the fixing device 17 side as needed, facing the conductive driving roller 14d grounded with the toner image receiving member 14a interposed therebetween. Then, 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 toner image receiver 14a is discharged and separated from the toner image receiver 14a.

The transport section 160 includes a separation claw 210 which is a claw member.
And a front spur 172 serving as a first spur member and a rear spur 162 serving as a second spur member. The curvature unit KT at the end of the toner image receiver 14a on the fixing device 17 side and the fixing device 17 It is provided between them. The conveyance unit 160 may cause the toner image receiver 14a to be deformed by the heat from the fixing device 17, cause the toner image carried on the toner image receiver 14a to be slightly fused, and become difficult to be transferred, or This prevents the toner from sticking to the body 14a.

The separation claw 210, which is a claw member, approaches the curvature portion KT of the toner image receiver 14a, and
Is fixed to the support shaft 215 with a predetermined interval, preferably 0.1 to 2.0 mm, provided when the recording paper P is separated from the toner image receiver 14a.
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 first spur member 172, which is the first spur member, is a spur member having a plurality of projections 172a (see FIG. 5) on its peripheral surface. It is provided so as to be rotatable about a rotation support shaft 175. The front spur 172 scoops up the leading end of the recording paper P separated by contacting the separation claw 210, and conveys the recording paper P to the rear spur 162 while guiding the back side of the recording paper P, and forms toner on both sides. The disturbance of the toner image on the back surface of the recording paper P having the image is prevented.

The rear spur 162, which is the second spur member, is a spur member having a plurality of projections 162a (see FIG. 5) on its peripheral surface, and is located downstream of the front spur 172 in the transport direction of the recording sheet P. The rotation support shaft 165 is provided rotatably about the rotation support shaft 165. The rear spur 162 guides the back side of the recording sheet P to convey the recording sheet P, prevents the toner image on the back side of the recording sheet P from being disturbed, and prevents the rear spur 172 from being disturbed.
Thus, the recording paper P is stably conveyed to the fixing device 17 while the direction in which the recording paper P enters the fixing device 17 is kept constant.

The fixing device 17 serving 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 is simultaneously 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, image writing is started by the first exposure signal, that is, an electric signal corresponding to the Y image data, by the Y exposure optical system 12. An electrostatic latent image corresponding to the Y image of the original image is formed on the front surface.

The latent image is reversal-developed in a non-contact state by the Y developing device 13, and 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, an exposure optical system 12 for K, and a developing device 13 for K. A superimposed 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. (Toner image forming means).

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 first image carrying means by the above-described image forming process, is used as the first transfer means in the transfer area 14b. The next transfer unit 14c collectively transfers the toner image onto the toner image receiving body 14a as the second image carrying means (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 a first image carrier cleaning means, or is exposed to light. The toner is cleaned by a cleaning blade 19a made of a rubber material in contact with the body drum 10 and collected by a screw 19b in a waste toner container (not shown). The history of the photosensitive drum 10 in the previous image formation on the peripheral surface of the photosensitive drum 10 is eliminated by, for example, exposure by the uniform exposure device 12e before charging using a light emitting diode.

After the superimposed color toner image serving as the back image is formed on the toner image receiving member 14a as described above, the surface of the photoreceptor drum 10 is continuously formed in the same manner as in the above-described color image forming process. A superimposed color toner image serving as an image 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 a 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 driven by the timing roller 15b to synchronize the color toner image of the front surface image formed on the photosensitive drum 10 with the color toner image of the rear surface image carried on the toner image receiver 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 surface side of the recording paper P, and is attracted to the toner image receiving member 14a and transferred. It is fed to the area 14b. By charging the paper with the same polarity as the toner, the toner is prevented from being attracted to the toner image on the toner image receiving member 14a or 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 capable of contacting and releasing contact with the toner image receiver 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 polarity 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 toner image receiver 14a is not transferred to the recording paper P but exists on the toner image receiver 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 toner image receiver 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 used as a transfer material separating means provided at the end of the toner image receiving member 14a and the curvature of the curvature portion KT of the toner image receiving member 14a. Is separated from the toner image receiver 14a by the paper removing AC neutralizer 14h and the separation claw 210 provided on the conveyor 160 at a predetermined distance from the toner image receiver 14a. The recording paper P is conveyed to the fixing device 17 as fixing means through the front spur 172 and the rear spur 162, and is applied with heat and pressure at a nip portion T between the fixing roller 17a and the pressure roller 17b. Is fixed. 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 toner image receiver 14a after the transfer is provided to face the guide roller 14f with the toner image receiver 14a interposed therebetween, and the toner image receiver 14 is supported by the support shaft 142 as a rotation fulcrum. The toner image receiving member is cleaned by a toner image receiving member cleaning device 140 which is a second image carrying means cleaning means having a toner image receiving member cleaning blade 141 capable of contacting and releasing contact with 14a.

The toner remaining on the peripheral surface of the photoreceptor drum 10 after the transfer is subjected to static elimination by the photoreceptor drum AC static eliminator 16 and then cleaned by the cleaning device 19 to remove the toner. By 12e, the history of the photosensitive drum 10 in the previous image formation is eliminated, and the next image formation cycle is started.

Since the superimposed color toner images are collectively transferred by using the above-described method, the color image on the toner image receiving member 14a is hardly discolored, the toner is scattered or rubbed, and the image deterioration is small. A double-sided color image is formed.

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 image forming apparatus of the present invention, in addition to the double-sided image formation for forming an image on both sides of the transfer material as described in the above-described embodiment, the image is formed on only one surface of the transfer material. It goes without saying that single-sided image formation can also be performed.

Next, the claw member provided in the transport section and the first
The spur member and the second spur member are shown in FIGS.
This will be described with reference to FIG.

The driving roller 14d, which is a roller member, is driven and rotated by the rotation of the driving motor M1.
The drive rotation of d rotates the toner image receiver 14a counterclockwise as indicated 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 a fixing device 1 for the toner image receiver 14a.
The toner image is separated from the toner image receiving body 14 a at a curvature section KT provided at the end on the 7th side, and is conveyed to the fixing device 17 through the conveying section 160. The transport unit 160 includes, in order from the upstream side in the transport direction of the recording paper P, a separation claw 210 serving as a claw member,
A front spur 172 as a first spur member and a rear spur 162 as a second spur member are respectively arranged in parallel in a direction perpendicular to the conveying direction of the recording paper P, that is, in a longitudinal direction of the fixing device 17. Will be arranged. The separating claw 210 has a curvature portion KT at an end of the toner image receiving member 14a on the fixing device 17 side.
And a toe portion 211 of the separation claw 210.
The distance between a and the center of rotation of the front spur 172 is about 5 to 30 mm, the distance between the center of rotation of the front spur 172 and the center of rotation of the rear spur 162 is about 10 to 50 mm, and the center of rotation of the rear spur 162 and the fixing device 17 are fixed. The distance from the position where the transfer material enters (hereinafter also referred to as the entrance of the nip portion T) is about 20 to 60 mm.

The separation claw 210 is fixed to a predetermined position of, for example, a quadrangular rod-shaped support shaft 215 by, for example, an adhesive, and the front spur 172 has its rotation center at the rotation support shaft 1.
And is rotatably mounted at a predetermined position by an E-ring E. The support shaft 215 and the rotation support shaft 175
The separation claws are fixed to holders 169a and 169b at both ends attached to the upstream side of the transporting unit housing 161 in the transporting direction of the recording paper P, and are separated in the direction orthogonal to the transporting direction of the recording paper P, that is, in the longitudinal direction of the fixing device 17. 210 and front spur 17
2 are arranged in parallel with each other.

The rear spur 162 is passed through a center hole through a rotation support shaft 165 made of, for example, a metal bar, and both ends are rotatably stopped at predetermined positions of the rotation support shaft 165 by E-rings E. The rotation support shaft 165 is inserted into a hole of a semicircular stop 163b on the opposite side of the guide surface 163a of the transport guide member 163, and the plurality of transport guide members 163 are parallel to the transport direction of the recording paper P and the transport unit housing. 161 is fixed to a predetermined position, and both ends of the rotation support shaft 165 are stopped by the E-ring E and fixed to the transport unit housing 161 to configure the transport unit 160.

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. 0.1 to 2.0 mm with toner image receiver 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 front spur 172 has a thickness of 0.05 to 0.5 m obtained by etching a metal plate such as a stainless steel plate or a copper plate.
m, outer diameter of 3 to 20 mm, thickness of 0.5 to 2.0 m
m, a resin member having an outer diameter of 3 to 20 mm is used, and is made of a polygonal member, for example, a hexagonal plate member provided with a plurality of sharp projections 172a at its tip.

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

The recording paper P separated by the separation claw 210 is scooped up by the front spur 172 at the leading end of the recording paper P and sent to the front spur 172, where the projection 172 of the front spur 172 is provided.
a contacts the recording paper P or pierces the recording paper P.
Is driven to rotate, and the recording paper P is conveyed to the rear spur 162 while the toner image is not rubbed and the direction of entry into the fixing device 17 is kept constant.

The rear spur 162 guides the back side of the recording sheet P to convey the recording sheet P, prevents the back side toner image of the recording sheet P having the toner image on the back side from being disturbed, and enters the fixing device 17. The recording paper P is conveyed to the fixing device 17 while keeping the direction constant.

As described above, the advancing direction of the leading end of the recording paper P after coming into contact with the separation claw 210 is unstable, but by providing two rows of spur members as the first and second spur members, The traveling direction of the leading end of the recording paper P can be made substantially constant. That is, the role of each spur member is different, and the front spur 172, which is the first spur member in the first row, plays a role of scooping up the leading end of the recording paper P, and the second spur member in the second row is the record. It determines the direction of travel of the leading end of the paper P and serves to guide the back side of the recording paper P.

When the separating claw 210, the front spur 172, and the rear spur 162 are made of a metal plate, 10 ⁸ to 10 ⁸ are formed via a support shaft 215 and rotary support shafts 175, 165 formed of a metal member.
It is preferable to be grounded through a high resistance body of 10 ¹⁴ Ω. The separation claw 210, the front spur 172, and the rear spur 162 are grounded through a high-resistance body to prevent charge accumulation on the separation claw 210, the front spur 172, and the rear spur 162 and the adhesion of toner due to the mirror image force, thereby preventing the toner image from forming. Disturbance can be prevented. Further, the separation claws 210, the front spur 172, and the rear spur 162 made of a metal plate are floated, or a voltage of the same polarity as the toner (negative polarity in this embodiment) is applied to these metal plates to prevent toner adhesion. However, it is also possible to prevent disturbance of the toner image. In addition, separation claw 21
By using an insulating member such as an insulating resin member for the zero, front spur 172, and rear spur 162, the separation claw 210, the front spur 172, and the rear spur 162 are used in the same manner as in the above-described floating.
This prevents the toner from accumulating due to the charge accumulation and the mirror image force, thereby preventing the toner image from being disturbed. 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 surface side (upper side) of the rotation center of the rear spur 162. As a result, even when the leading end of the recording paper P that is separated from the toner image receiving body 14a by the separation claw 210 and conveyed to the rear spur 162 through the front spur 172 is in contact with the guide surface 163a, the recording paper P is picked up by the guide surface 163a. It is sent to the spur 162 and the rear spur 162
The rear spur 162 is driven and rotated in a state where the projection 162a contacts or pierces the recording paper P, and the recording paper P is conveyed to the fixing device 17 without rubbing the toner image.

When the recording paper P conveyed by the toner image receiver 14a is separated from the toner image receiver 14a at the curvature KT at the end of the toner image receiver 14a, the curvature portion at the end of the toner image receiver 14a is used. Driving roller 1 constituting KT
The radius of curvature of 4d is preferably 15 mm or less, more preferably 10 mm or less. By setting the radius of curvature to 15 mm or less and providing a paper separation AC neutralizer 14h as a transfer material separating unit facing the end of the toner image receiver 14a as in the present embodiment, the curvature of the toner image receiver 14a is reduced. Paper separation 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 curvature of the end of the toner image receiver 14a and the separation claw 210 cause the recording paper P from the toner image receiver 14a to be removed. Separation is performed stably,
The movement of the recording paper P to the transport unit 160 is also performed stably.

With respect to the first aspect of the present invention,
This will be described with reference to FIGS. 6 to 8 and FIG. FIG.
FIG. 7 is a diagram illustrating a state of separation of the transfer material conveyed by the second image holding unit by the claw member, and FIG. 7 is a diagram illustrating a state of passage of the transfer material after separation by the claw member through the first spur member. FIG. 8 is a diagram showing a state in which the transfer material passes through the first spur member and the second spur member.

The recording paper P on which the color toner images are formed on both sides is used as a transfer material separating means provided at the end of the toner image receiving member 14a and the curvature of the curvature portion KT of the toner image receiving member 14a. Is separated from the toner image receiving body 14a by the static elimination action of the paper separating AC static eliminator 14h and the separation claw 210 provided at a predetermined interval from the toner image receiving body 14a, and is fixed through the front spur 172 and the rear spur 162. The toner image on the recording paper P is fixed by being conveyed to the fixing device 17 as a means and applied with heat and pressure at a nip portion T between the fixing roller 17a and the pressure roller 17b.

As shown in FIG. 6, the leading end of the recording paper P conveyed to the curvature portion KT of the toner image receiving member 14a stretched over the driving roller 14d is fixed to the toner image receiving member 14a by the support shaft 215. Separation claw 21 fixed with an interval
The recording paper sheet P is brought into contact with the toe part 211a of 0, and the leading end of the recording paper P is flipped up in the direction of the dotted arrow with the force of being caught by the toe part 211a.

Subsequently, as shown in FIG. 7, the leading end of the recording paper P separated from the curvature portion KT of the toner image receiving member 14a is disposed close to the separation claw 210,
5 to scoop up by the protruding portion 172a of the front spur 172 which is rotatable. After the leading edge of the recording paper P is scooped, the recording paper P is conveyed so that the back side of the recording paper P does not contact the separation claw 210.

Subsequently, as shown in FIG. 8, the recording paper P sent by the front spur 172 is conveyed to the rotatable rear spur 162 by the rotation support shaft 165, and the protrusion 1 of the front spur 172 is provided.
The recording paper P is conveyed by guiding the rear surface side by the projections 162a of the rear spur 162 and the fixing roller 17a of the fixing device 17 and the pressure roller. 17b.

As described above, the recording paper P is transferred to the toner image receiver 1
4A can be satisfactorily separated from the recording paper P, and can be stably conveyed to the fixing device 17 while preventing disturbance of the back side toner image of the recording paper P having the toner images on both sides.

In the above case, if there is only one spur member, the advancing direction of the leading end of the recording paper P varies depending on how the recording paper P jumps up at the time of separation by the separation claw 210, and the toner image on the back side This may cause turbulence and fixing wrinkles.

The second invention according to claim 2 or 3 will be described with reference to FIGS. FIG.
FIG. 10 is a diagram illustrating a positional relationship between a claw member, a first spur member, and a second spur member with respect to a transfer material conveying surface of a second image bearing unit, and radii of curvature of the first and second spur members; FIG. 11 is a diagram showing an unfavorable example of the positions of the first and second spur members in FIG. 9; FIG. 11 is a diagram showing an optimal position of the claw member with respect to the curvature portion of the second image carrying means;

The recording paper P on which the color toner images are formed on both sides is used as a transfer material separating means provided at the end of the toner image receiving member 14a and the curvature of the curvature portion KT of the toner image receiving member 14a. Is separated from the toner image receiving body 14a by the static elimination action of the paper separating AC static eliminator 14h and the separation claw 210 provided at a predetermined interval from the toner image receiving body 14a, and is fixed through the front spur 172 and the rear spur 162. The toner image on the recording paper P is fixed by being conveyed to the fixing device 17 as a means and applied with heat and pressure at a nip portion T between the fixing roller 17a and the pressure roller 17b.

As shown in FIG. 9, the toner image receiving member 14a
The closest distance between the conveying surface of the recording paper P conveyed by the recording medium P or an extended surface thereof (hereinafter, referred to as a transfer material conveying surface PL1) and the separation claw 210 claw is H1 (mm), and the transfer material conveying surface PL1 and the first spur member H2 (mm), and the closest distance between the transfer material transport surface PL1 and the second spur member is H3 (m).
m), H3 ≦ H2 <H1. As a result, the back surface of the recording paper P is not rubbed by the separation claw 210, and the traveling direction of the leading end of the recording paper P becomes substantially constant, so that the recording paper P enters the fixing device 17 stably.

In the case of H2> H1, the back surface of the recording paper P is rubbed by the separation claw 210, and the back toner image is disturbed. Also H
In the case of 3 ≧ H2, as shown in FIG. 10, the traveling direction of the leading end of the recording paper P cannot be determined by the rear spur 162, the approaching direction to the fixing device 17 varies, and the toner image on the back side is disturbed. And cause wrinkles.

The curvature portion KT of the toner image receiver 14a stretched and formed by the drive roller 14d shown in FIG.
Is preferably 15 mm or less, and more preferably 10 mm or less as described above. If the radius of curvature R exceeds 15 mm, it is difficult to separate the curvature when the environment changes (when the temperature is 25 ° C. and the humidity is 40% or less) or when thin paper is used as the recording paper P.
4h is required. Usually, the radius of curvature R is 15 mm or less and the paper separation AC static eliminator 14h may not be provided. In the case of a change in environmental change or when thin paper is used as the recording paper P, the paper separation AC neutralizer 14h with the radius of curvature R of 10 mm or less is used. Need not be provided.

Further, the curvature portion K of the toner image receiving body 14a
For the radius of curvature R at T, the closest distance H1 between the transfer material transport surface PL1 and the toe portion 211a of the separation claw 210 is set to 0.
It is preferable that 3 × R ≦ H1 ≦ 0.9 × R. That is, it is preferable to dispose the toe portion 211a in a position indicated by a thick line in FIG. When 0.3 × R> H1, the back surface of the recording paper P may be rubbed against the separation claw 210.
When H1> 0.9 × R, the leading end of the recording paper P may be caught on the toe portion 211a of the separation claw 210, or the leading end may be bent.

[0082] Regarding the third invention according to claim 4,
This will be described with reference to FIGS. 9 and 12 described above. FIG. 12 is a diagram illustrating an example of an unfavorable radius of curvature of the first and second spur members of FIG. 9.

The recording paper P on which the color toner images are formed on both sides is used as a transfer material separating means provided at the end of the toner image receiver 14a and the curvature of the curvature portion KT of the toner image receiver 14a. Is separated from the toner image receiving body 14a by the static elimination action of the paper separating AC static eliminator 14h and the separating claw 210 provided at a predetermined interval from the toner image receiving body 14a, and is fixed through the front spur 172 and the rear spur 162. Is transported to the fixing device 17 as a
The toner image on the recording paper P is fixed by applying heat and pressure at a nip T between the pressure roller 7a and the pressure roller 17b.

As shown in FIG. 9, the radius of curvature of a circle (peripheral surface) formed by the projection 172a of the front spur 172 is r1 (m
m), when the radius of curvature of the circle formed by the protrusion 162a of the rear spur 162 is r2 (mm), r1 <r2.
That is, the diameter of the spur member on the upstream side in the transport direction of the recording paper P is made smaller than the diameter of the spur member on the downstream side. r1 is usually 1
R2 is about 3 to 20 mm, preferably 5 to 10 mm.
By scooping up the leading end of the recording paper P flipped up by the separation claw 210 with the front spur 172 having a small diameter, it is possible to reduce the variation in the traveling direction of the recording paper P after passing through the front spur 172.

When r1 ≧ r2, that is, when the separation claw 210
The leading end of the recording paper P flipped up by the large spur 17
In the case of scooping up by 2, the front end portion is easily caught by the front spur 172, and as shown in FIG.
After passing through the recording paper P, the leading end of the recording paper P is caught by the small rear spur 162, so that the traveling direction of the recording paper P is easily affected by the vertical movement of the large front spur 172 on the front side, and the fixing paper 17 Invaders vary.

The fourth invention according to claim 5 is as follows:
This will be described with reference to FIG. FIG. 13 is a diagram illustrating an interval (pitch) between protrusions of the first spur member and the second spur member.

The recording paper P on which the color toner images are formed on both sides is used as a transfer material separating means provided at the end of the toner image receiving member 14a and the curvature of the curvature portion KT of the toner image receiving member 14a. Is separated from the toner image receiving body 14a by the static elimination action of the paper separating AC static eliminator 14h and the separation claw 210 provided at a predetermined interval from the toner image receiving body 14a, and is fixed through the front spur 172 and the rear spur 162. The toner image on the recording paper P is fixed by being conveyed to the fixing device 17 as a means and applied with heat and pressure at a nip portion T between the fixing roller 17a and the pressure roller 17b.

In this example, as shown in FIG. 13, an octagonal front spur 272 is provided as a first spur member instead of the hexagonal front spur 172 described above.
The distance (pitch) between two adjacent protrusions 272a is P1
(Mm), P1 <P2 when the interval (pitch) between the adjacent protrusions 162a of the rear spur 162 is P2 (mm). That is, the pitch of the spur member on the upstream side in the transport direction of the recording paper P is made smaller than the pitch of the spur member on the downstream side. P1 is usually about 0.5 to 5 mm, preferably 1 to 3 mm.
mm, and P2 is usually about 2 to 10 mm, preferably 3
７7 mm. By scooping up the leading end of the recording paper P flipped up by the separation claw 210 with the projection 272a of the front spur 272, which is the first spur member having a small pitch,
The vertical movement of the recording paper P when passing through the front spur 272 is reduced, and the variation in the traveling direction of the recording paper P after passing through the front spur 272 can be reduced. Further, since the vertical movement at the position of the front spur 272 is small, the back side of the recording paper P and the separation claw 210 are not rubbed.

When P1 ≧ P2, since the recording paper P moves up and down when passing through the front spur 272, the back surface of the recording paper P rubs against the separation claw 210. In addition, the traveling direction of the recording paper P after passing through the front spur 272 varies, and the direction is changed to the protrusion 162 of the rear spur 162 which is a second spur member having a small pitch.
Therefore, the traveling direction of the recording sheet P is greatly affected by the vertical movement of the front spur 272, and the entry of the recording sheet P into the fixing device 17 is finally varied.

The fifth invention according to claim 6 or 7 will be described with reference to FIGS. FIG.
FIG. 15 shows a positional relationship between the claw member, the first spur member, the second spur member, and the transport guide member and the respective numbers thereof. FIG. 15 is a perspective view showing a virtual sectional view of FIG. And FIG. 16 is a diagram showing a preferred arrangement of the second spur member of FIG. 14. FIG. 17 is a diagram showing an example of an unfavorable distance between the first spur member and the claw member of FIG.

The recording paper P on which the color toner images are formed on both sides is used as a transfer material separating means provided at the end of the toner image receiving member 14a and the curvature of the curvature portion KT of the toner image receiving member 14a. Is separated from the toner image receiving body 14a by the static elimination action of the paper separating AC static eliminator 14h and the separation claw 210 provided at a predetermined interval from the toner image receiving body 14a, and is fixed through the front spur 172 and the rear spur 162. The toner image on the recording paper P is fixed by being conveyed to the fixing device 17 as a means and applied with heat and pressure at a nip portion T between the fixing roller 17a and the pressure roller 17b.

As shown in FIGS. 14 and 15, the recording paper P conveyed by the toner image receiving member 14a is perpendicular to the transfer material conveyance plane PL1 and crosses the central portion of the separation claw 210 in the conveyance direction of the recording paper P. The closest distance between the virtual cross section PL2 (hereinafter referred to as the virtual cross section PL2) and the peripheral surface of the front spur 172 which is the first spur member closest to the virtual cross section PL2 is d1 (mm), and the virtual cross section PL2 And virtual cross section PL2
When the closest distance to the peripheral surface of the rear spur 162, which is the second spur member closest to the second spur member, is d2 (mm), d1 <d2. That is, the front spur 172 is provided near the separation claw 210 and the rear spur 162 is provided away from the separation claw 210 in a direction perpendicular to the recording paper P conveyance direction. d1 usually has a value of about 0 to 10 mm, preferably 5 mm or less, and d3 has a value of usually about 50 to 150 mm.
Further, as shown in FIG. 16, the rear spur 162 is arranged such that the separation cross section PL2 crosses the virtual cross section PL2 so that the rear spur 162 is located near the center of the adjacent separation claw 210, and is closest to the virtual cross section PL2. When the distance between the separation claw 210 adjacent to the rear spur 162 is d3 (mm), it is 0.
It is preferable that 3 × d3 ≦ d2 ≦ 0.7 × d3.
The rear spur 162 is located at an intermediate position (d2
= 0.5 × d3).
Since the leading end of the recording paper P flipped up by the separation claw 210 is scooped by the front spur 172 provided near the separation claw 210, the back side of the recording paper P and the separation claw 210 are not rubbed. Also, the back surface of the recording paper P that is going to hang down to the back side between the adjacent separation claws 210 is
Since it is guided by the rear spur 162 provided away from the fixing device 17 to enter the fixing device 17, there is no occurrence of fixing wrinkles.

When the distance d1 is increased, the front spur 172 is
When the recording paper P is provided apart from 0, as shown in FIG. 17, the recording paper P falls to the back side between the adjacent front spurs 172, and the hanging part of the recording paper P rubs against the separation claw 210. Further, it becomes difficult to catch the leading end of the recording paper P that has been flipped up by the separation claw 210. Set d2 to small and rear spur 1
When 62 is provided near the virtual cross section PL2, the central portion of the recording paper P falls to the back side between the adjacent separation claws 210, and the recording paper P enters the fixing device 17 in this state. Fixing wrinkles are likely to occur.

A sixth aspect of the present invention will be described with reference to FIGS. 14 and 18. FIG. 18 is a view showing an unfavorable example of the arrangement of the claw member and the first spur member which are arranged farthest apart.

The recording paper P on which the color toner images are formed on both sides is used as a transfer material separating means provided at the end of the toner image receiving member 14a and the curvature of the curvature portion KT of the toner image receiving member 14a. Is separated from the toner image receiving body 14a by the static elimination action of the paper separating AC static eliminator 14h and the separation claw 210 provided at a predetermined interval from the toner image receiving body 14a, and is fixed through the front spur 172 and the rear spur 162. The toner image on the recording paper P is fixed by being conveyed to the fixing device 17 as a means and applied with heat and pressure at a nip portion T between the fixing roller 17a and the pressure roller 17b.

As shown in FIG. 14, the separation claw 2 farthest away
10 is W1 (mm), the farthest front spur 172
W1 (W) (mm) and W3 (mm) the distance between the farthest rear spurs 162, W1 ≦ W2 <W3. That is, of the members, the width of the member on the downstream side in the transport direction of the recording paper P is wider than the width of the member on the upstream side. As described above, even when both ends of the recording paper P hang down to the back side, the portions rub against the separation claw 210,
It is possible to prevent occurrence of fixing wrinkles.

When W1> W2, as shown in FIG. 8, both ends of the recording paper P on both sides (outside) of the front spur 172 are lowered to the back side, and the part is rubbed against the separation claw 210. . When W2 ≧ W3, the rear spur 162
On both sides (outside) of the recording paper P, both ends are lowered to the back side,
In this state, since the sheet enters the fixing device 17, fixing wrinkles occur at both ends.

Also, the distance W between the farthest rear spurs 162
3 (mm) is 0.8 × W when the maximum width of the recording paper P in a direction orthogonal to the conveying direction of the recording paper P is W4 (mm).
It is preferable that 4 ≦ W3 ≦ 0.95 × W4. 0.
When 8 × W4> W3, both ends of the recording paper P are easily lowered and fixing wrinkles are likely to occur. When W3> 0.95 × W4, the conveyance of the recording paper P is shifted to the front side (or the back side). In this case, the end of the recording paper P is not caught on the rear spur 162 at the outermost end.

The seventh aspect of the present invention will be described with reference to FIG.

The recording paper P on which the color toner images are formed on both sides is used as a transfer material separating means provided at the end of the toner image receiving member 14a and the curvature of the curvature portion KT of the toner image receiving member 14a. Is separated from the toner image receiving body 14a by the static elimination action of the paper separating AC static eliminator 14h and the separation claw 210 provided at a predetermined interval from the toner image receiving body 14a, and is fixed through the front spur 172 and the rear spur 162. The toner image on the recording paper P is fixed by being conveyed to the fixing device 17 as a means and applied with heat and pressure at a nip portion T between the fixing roller 17a and the pressure roller 17b.

As shown in FIG. 14, when the number of separation claws 210 is N1, the number of front spurs 172 is N2, and the number of rear spurs 162 is N3, N1 ≦ N2 and N1 + 1.
≤ N3. That is, the front spur 172 is
To catch the leading end of the recording paper P flipped up by
The number of the separation claws 210 is equal to or greater than the number of the separation claws 210, and the rear spur 162 is provided at an intermediate position or outside of the separation claws 210, so that at least one more than the separation claws 210 is provided. As described above, when the leading edge of the recording paper P flipped up by the separation claw 210 is picked up by the front spur 172, the recording paper P
There is no rubbing between the back side of the recording paper P and the separation claw 210, and when the recording paper P enters the fixing device 17, the recording paper P does not hang down to the rear side and no wrinkles are generated.

When N1> N2, the back surface of the recording paper P is rubbed against the separation claw 210. In the case of N1 + 1> N3, the recording paper P undulates in the direction orthogonal to the transport direction (the rear spur 16
2 is small), and fixing wrinkles occur.

In order to make the direction in which the recording paper P enters the fixing device 17 more constant, a rear spur 162 serving as a second spur member is used.
May be provided in two or more rows parallel to the longitudinal direction of the fixing device 17.

The number N1 of the separation claws 210 is set to 3 ≦ N
1 ≦ 5 (the number N1 is 3 to 5), and the number N2 of the front spur 172 and the number N3 of the rear spur 162 are N2 = N1 (the number N2 is 3 to 5) and N3 = N, respectively.
1 + 1 (the number N2 is 4 to 6) is preferable.

If the numbers N1, N2, and N3 are too small, it may not be possible to stably convey various types of recording paper P having different widths. If the numbers N1, N2, and N3 are too large, the back surface of the recording paper P as a transfer material may be separated. The recording paper P may be rubbed against the nail 210
Of the front spur 172 as the second spur member and the rear spur 162 as the second spur member.

An eighth aspect of the present invention will be described with reference to FIGS. 14 and 19. FIG. 19 is a diagram illustrating a preferred arrangement of the transport guide member and the second spur member.

The recording paper P on which the color toner images are formed on both sides is used as a transfer material separating means provided at the end of the toner image receiving member 14a and the curvature of the curvature portion KT of the toner image receiving member 14a. Is separated from the toner image receiving body 14a by the static elimination action of the paper separating AC static eliminator 14h and the separation claw 210 provided at a predetermined interval from the toner image receiving body 14a, and is fixed through the front spur 172 and the rear spur 162. The toner image on the recording paper P is fixed by being conveyed to the fixing device 17 as a means and applied with heat and pressure at a nip portion T between the fixing roller 17a and the pressure roller 17b.

As shown in FIG. 14, the adjacent rear spur 16
2, a conveyance guide member 163 that can guide the back side of the recording paper P and extends in the conveyance direction of the recording paper P is provided.
As a result, even when the leading end of the recording sheet P is slightly lowered toward the rear side and is conveyed to the rear spur 162, the recording sheet P
The hanging portion is lifted to the front side by the conveyance guide member 163, so that the rear spur 162 can be properly caught and the recording paper P is stably conveyed to the fixing device 17.

When the transport guide member 163 is not provided, when the leading end of the recording paper P is slightly lowered, the leading end is caught by the protrusion 162a of the rear spur 162, and a jam occurs or the rear spur 162 passes safely. Even when the fixing device 17 enters the fixing device 17, the wrinkles are generated.

FIG. 19 shows an octagonal rear spur 26 instead of the hexagonal rear spur 162 described above as a second spur member.
In this example, the plane PL3 including the guide surface 163a of the transport guide member 163 is provided on the front side (upper side) of the recording sheet P with respect to the rotation center of the rear spur 262. As a result, even when the leading end of the recording paper P separated from the toner image receiving body 14a by the separation claw 210 and conveyed to the rear spur 262 through the front spur 172 comes into contact with the guide surface 163a, the recording paper P is picked up by the guide surface 163a. Spur 26
2 and the protrusion 262a of the rear spur 262 is
The rear spur 262 is driven and rotated in a state of contacting or piercing the recording paper P, and the recording paper P is conveyed to the fixing device 17 without rubbing the toner image. Further, it is preferable to provide a rear spur 262 having a polygonal shape, for example, an octagon or more, such that at least three protrusions 262a are protruded from the surface of the recording paper P with respect to the plane PL3.

A ninth aspect of the present invention will be described with reference to FIGS. FIG.
It is a figure which shows what provided the claw member and the 1st spur member support member integrally, and FIG. 21 is a figure which shows the 1st example of the claw member which integrated the 1st spur member support member. , FIG.
Is a second claw member integrated with the first spur member supporting member.
It is a figure showing the example of.

The recording paper P on which the color toner images are formed on both sides is used as a transfer material separating means provided at the end of the toner image receiving member 14a and the curvature of the curvature portion KT of the toner image receiving member 14a. Is separated from the toner image receiving body 14a by the static elimination action of the paper separating AC static eliminator 14h and the separation claw 210 provided at a predetermined interval from the toner image receiving body 14a, and is fixed through the front spur 172 and the rear spur 162. The toner image on the recording paper P is fixed by being conveyed to the fixing device 17 as a means and applied with heat and pressure at a nip portion T between the fixing roller 17a and the pressure roller 17b.

As shown in FIG. 20, the front spur 172 as the first spur member is preferably disposed near the separation claw 210 as the claw member.
A first rotatably supporting the separation claw 210 and the front spur 172
And an integral support shaft 275 which is a spur member support member. Further, the upper surface portion 211b of the separation claw 210 with which the back surface of the recording paper P abuts has a concave shape curved toward the back surface.
The integral support shaft 275 supporting the front spur 172 is separated from the separation claw 21.
0, the separation pawl 210 and the front spur 172 are easily aligned, and after the recording paper P is separated from the toner image receiver 14a by the toe portion 211a of the claw portion 211 of the separation claw 210, The front spur 1 in which the recording paper P is immediately separated from the separation claw 210 and integrated with the separation claw 210
The recording paper P is guided by the rear spur 72 and carried over by the rear spur 162, so that the separated recording paper P is favorably transported to the fixing device 17. The upper surface 211b of the separation claw 210 is formed into a concave shape curved to the back side, so that when the leading end of the recording paper P abutting on the separation claw 210 is scooped by the front spur 172, the back surface of the recording paper P is separated. Contact with the nail 210 can be prevented. As the separation claw 210 in which the integral support shaft 275 of the front spur 172 is integrated,
As shown in FIG. 21, a separation claw 220 having a claw portion 221 provided with a concave upper surface portion 221 b curved in a C-shape on the back surface, or a concave claw shape on the back surface side as shown in FIG. 22. A separation claw 230 having a claw portion 231 provided with an upper surface portion 231b formed of a surface is used.

[0114]

According to the present invention, the second image bearing means and the toner image on the second image bearing means are not affected by the heat from the fixing means, and the transfer material is the second image bearing means. The transfer material is satisfactorily separated from the fixing means, and the transfer material is stably conveyed to the fixing means without disturbing (rubbing) the toner image on the back surface.

[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 a first image bearing unit 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 showing a claw member, a first spur member, and a second spur member.

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

FIG. 6 is a diagram illustrating a state in which a transfer material conveyed by a second image bearing unit is separated by a claw member;

FIG. 7 is a diagram showing a state in which a transfer material after separation by a claw member passes through a first spur member.

FIG. 8 is a diagram illustrating a state in which a transfer material passes through a first spur member and a second spur member.

FIG. 9 is a diagram illustrating a positional relationship between a claw member, a first spur member, and a second spur member with respect to a transfer material conveying surface of a second image bearing unit, and a radius of curvature of the first and second spur members. is there.

FIG. 10 is a view showing an unfavorable example of the positions of the first and second spur members of FIG. 9;

FIG. 11 is a diagram illustrating an optimum position of a claw member with respect to a curvature portion of a second image bearing unit.

12 is a diagram showing an example of an unfavorable radius of curvature of the first and second spur members of FIG. 9;

FIG. 13 is a diagram showing an interval (pitch) between protrusions of a first spur member and a second spur member.

FIG. 14 is a diagram illustrating a positional relationship between a claw member, a first spur member, a second spur member, and a conveyance guide member, and the respective numbers thereof.

FIG. 15 is a perspective view showing a virtual sectional view of FIG. 14;

FIG. 16 shows a preferred arrangement of the second spur member of FIG. 14;

FIG. 17 is a view showing an example of an unfavorable distance between the first spur member and the claw member in FIG. 14;

FIG. 18 is a view showing an unfavorable example of the arrangement of the claw member and the first spur member arranged farthest away from each other.

FIG. 19 is a diagram showing a preferred arrangement of a transport guide member and a second spur member.

FIG. 20 is a diagram showing a structure in which a claw member and a first spur member supporting member are integrally provided.

FIG. 21 is a diagram illustrating a first example of a claw member in which a first spur member supporting member is integrated.

FIG. 22 is a diagram showing a second example of the claw member in which the first spur member supporting member is integrated.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 photoconductor drum (first image holding unit) 11 scorotron charger 12 exposure optical system 13 developing unit 14a toner image receiver 14c primary transfer unit (first transfer unit) 14d drive roller 14g secondary transfer unit (first transfer unit) 2 transfer means) 17 fixing device (fixing means) 160 transport section 162, 262 rear spur (second spur member) 162a, 172a, 262a, 272a protrusion 163 transport guide member 172, 272 front spur (first spur) Members) 210, 220, 230 Separating claws (claw members) 211, 221, 231 Claw portions 211a Toe portions 211b, 221b, 231b Upper surface portion 275 Integrated support shaft KT Curvature portion P Recording paper (transfer material) PL1 Transfer material transport surface PL2 Virtual cross section T nip

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Satoshi Haneda 2970, Ishikawacho, Hachioji-shi, Tokyo Konica Corporation (72) Inventor Toshihide Miura 5-14-14 Midoricho, Koganei-shi, Tokyo

Claims (14)

[Claims] A first image carrying means for carrying the toner image formed by the toner image forming means; and a toner image carried by the first image carrying means is transferred. While supported on the surface,
A second image carrying means for conveying a transfer material; and a second image carrying means for carrying the toner image carried by the first image carrying means to the second image carrying means.
A first transfer unit that transfers the image on the surface of the transfer material, or a second transfer unit that transfers the toner image carried on the second image support onto the back surface of the transfer material; Fixing means for fixing the toner image transferred to the transfer material, wherein the transfer material is transferred from the second image bearing means to an end of the second image bearing means on the fixing means side. Providing a curvature portion for separation; providing a claw member for contacting the leading end of the transfer material in proximity to the curvature portion; and further rotatably downstream of the transfer material in the conveyance direction near the claw member. And a first spur member having a plurality of protrusions on the peripheral surface and guiding the rear surface side of the transfer material is provided. Further, between the first spur member and the fixing means,
A second spur member that is rotatable and has a plurality of protrusions on the peripheral surface and guides the back side of the transfer material is provided, and the tip end of the transfer material separated from the second image bearing unit is After being brought into contact with the claw member, the first spur member scoops up, and the first spur member and the second spur member make the approach direction to the fixing unit substantially constant, and enter the fixing unit. An image forming apparatus, wherein after the first spur member scoops up the front end of the transfer material, the back surface of the transfer material does not contact the claw member. 2. A first image carrying means for carrying a toner image formed by a toner image forming means, and a toner image carried by the first image carrying means is transferred. While supported on the surface,
A second image carrying means for conveying a transfer material; and a second image carrying means for carrying the toner image carried by the first image carrying means to the second image carrying means.
A first transfer unit that transfers the image on the surface of the transfer material, or a second transfer unit that transfers the toner image carried on the second image support onto the back surface of the transfer material; An image forming apparatus having a fixing unit for fixing a toner image transferred to a transfer material, wherein a claw member is arranged between the second image bearing unit and the fixing unit in order from an upstream side in a conveying direction of the transfer material. And a first spur member that is rotatable and has a plurality of protrusions on the peripheral surface and a second spur member that is rotatable and has a plurality of protrusions on the peripheral surface, respectively, And a closest distance between the extension surface of the transfer surface of the transfer material conveyed by the second image carrying means and the claw member is H1 (m
m), when the closest distance between the extension surface and the first spur member is H2 (mm) and the closest distance between the extension surface and the second spur member is H3 (mm), H3 ≦ An image forming apparatus, wherein H2 <H1. 3. When the radius of curvature of the end of the second image bearing means on the fixing means side is R (mm), R ≦ 15 and the closest point between the extension surface and the claw member. The image forming apparatus according to claim 2, wherein the distance H1 is 0.3 × R ≦ H1 ≦ 0.9 × R. 4. A first image carrying means for carrying a toner image formed by a toner image forming means, and a toner image carried by the first image carrying means is transferred. While supported on the surface,
A second image carrying means for conveying a transfer material; and a second image carrying means for carrying the toner image carried by the first image carrying means to the second image carrying means.
A first transfer unit that transfers the image on the surface of the transfer material, or a second transfer unit that transfers the toner image carried on the second image support onto the back surface of the transfer material; An image forming apparatus having a fixing unit for fixing a toner image transferred to a transfer material, wherein a claw member is arranged between the second image bearing unit and the fixing unit in order from an upstream side in a conveying direction of the transfer material. And a first spur member that is rotatable and has a plurality of protrusions on the peripheral surface and a second spur member that is rotatable and has a plurality of protrusions on the peripheral surface, respectively, The first spur member has a radius of curvature of r1 (mm);
When the radius of curvature of the second spur member is r2 (mm), r1 <r2. 5. A first image carrying means for carrying a toner image formed by a toner image forming means, and a toner image carried on the first image carrying means is transferred, and the transferred toner image is While supported on the surface,
A second image carrying means for conveying a transfer material; and a second image carrying means for carrying the toner image carried by the first image carrying means to the second image carrying means.
A first transfer unit that transfers the image on the surface of the transfer material, or a second transfer unit that transfers the toner image carried on the second image support onto the back surface of the transfer material; An image forming apparatus having a fixing unit for fixing a toner image transferred to a transfer material, wherein a claw member is arranged between the second image bearing unit and the fixing unit in order from an upstream side in a conveying direction of the transfer material. And a first spur member that is rotatable and has a plurality of protrusions on the peripheral surface and a second spur member that is rotatable and has a plurality of protrusions on the peripheral surface, respectively, The first spur member is provided with a plurality thereof in a direction orthogonal to the direction, and the distance between adjacent protrusions of the first spur member is set to P1 (m
m), the distance between adjacent protrusions of the second spur member is P
An image forming apparatus wherein P1 <P2 when 2 (mm). 6. A first image carrying means for carrying a toner image formed by a toner image forming means, and a toner image carried by the first image carrying means is transferred, and the transferred toner image is While supported on the surface,
A second image carrying means for conveying a transfer material; and a second image carrying means for carrying the toner image carried by the first image carrying means to the second image carrying means.
A first transfer unit that transfers the image on the surface of the transfer material, or a second transfer unit that transfers the toner image carried on the second image support onto the back surface of the transfer material; An image forming apparatus having a fixing unit for fixing a toner image transferred to a transfer material, wherein a claw member is arranged between the second image bearing unit and the fixing unit in order from an upstream side in a conveying direction of the transfer material. And a first spur member that is rotatable and has a plurality of protrusions on the peripheral surface and a second spur member that is rotatable and has a plurality of protrusions on the peripheral surface, respectively, A virtual cross section orthogonal to the transfer surface of the transfer material conveyed by the second image bearing means and crossing a central portion of the claw member in the transfer direction of the transfer material. And the first spur member closest to the cross section The closest distance to the surrounding surface is d1 (m
m), wherein d1 <d2, where d2 (mm) is the closest distance between the cross section and the peripheral surface of the second spur member closest to the cross section. 7. When a distance between a claw member crossed by the cross section and a claw member adjacent to the second spur member closest to the cross section is d3 (mm), 0.3 × d3 ≦ The image forming apparatus according to claim 6, wherein d2 ≦ 0.7 × d3. 8. A first image carrying means for carrying a toner image formed by a toner image forming means, and a toner image carried on the first image carrying means is transferred. While supported on the surface,
A second image carrying means for conveying a transfer material; and a second image carrying means for carrying the toner image carried by the first image carrying means to the second image carrying means.
A first transfer unit that transfers the image on the surface of the transfer material, or a second transfer unit that transfers the toner image carried on the second image support onto the back surface of the transfer material; An image forming apparatus having a fixing unit for fixing a toner image transferred to a transfer material, wherein a claw member is arranged between the second image bearing unit and the fixing unit in order from an upstream side in a conveying direction of the transfer material. And a first spur member that is rotatable and has a plurality of protrusions on the peripheral surface and a second spur member that is rotatable and has a plurality of protrusions on the peripheral surface, respectively, The distance between the claw members farthest away is W1 (mm), the distance between the first spur members farthest away is W2 (mm), and the distance between the first spur members is W2 (mm). When the distance between the spur members is W3 (mm), W1 ≦ W <Image forming apparatus characterized by the W3. 9. When the maximum width of the transfer material in the direction orthogonal to the conveying direction is W4 (mm), 0.8 × W4 ≦ W3 ≦ 0.95 × W4. An image forming apparatus according to claim 1. 10. A first image carrying means for carrying a toner image formed by a toner image forming means, and a toner image carried by the first image carrying means is transferred, and the transferred toner image is While supported on the surface,
A second image carrying means for conveying a transfer material; and a second image carrying means for carrying the toner image carried by the first image carrying means to the second image carrying means.
A first transfer unit that transfers the image on the surface of the transfer material, or a second transfer unit that transfers the toner image carried on the second image support onto the back surface of the transfer material; An image forming apparatus having a fixing unit for fixing a toner image transferred to a transfer material, wherein a claw member is arranged between the second image bearing unit and the fixing unit in order from an upstream side in a conveying direction of the transfer material. And a first spur member that is rotatable and has a plurality of protrusions on the peripheral surface and a second spur member that is rotatable and has a plurality of protrusions on the peripheral surface, respectively, N1 ≦ N2 and N1 + 1 ≦ N3, where N1 is the number of the claw members, N2 is the number of the first spur members, and N3 is the number of the second spur members. An image forming apparatus characterized in that: 11. The number N1 of the claw members is set to 3 ≦ N1 ≦ 5, and the number N2 of the first spur members and the number N3 of the second spur members are respectively represented by N2 = N1 and N3 = N1 + 1. The image forming apparatus according to claim 10, wherein: 12. A first image carrying means for carrying a toner image formed by a toner image forming means, and a toner image carried by the first image carrying means is transferred. While supported on the surface,
A second image carrying means for conveying a transfer material; and a second image carrying means for carrying the toner image carried by the first image carrying means to the second image carrying means.
A first transfer unit that transfers the image on the surface of the transfer material, or a second transfer unit that transfers the toner image carried on the second image support onto the back surface of the transfer material; An image forming apparatus having a fixing unit for fixing a toner image transferred to a transfer material, wherein a claw member is arranged between the second image bearing unit and the fixing unit in order from an upstream side in a conveying direction of the transfer material. And a first spur member that is rotatable and has a plurality of protrusions on the peripheral surface and a second spur member that is rotatable and has a plurality of protrusions on the peripheral surface, respectively, A plurality of transfer guide members are provided in a direction orthogonal to the direction, and a transfer guide member that can guide the back side of the transfer material and extends in the transfer direction of the transfer material is provided between the adjacent second spur members. Characteristic image forming apparatus. 13. A plane including a guide surface of the transport guide member is positioned closer to a surface of the transfer material than a rotation center of the second spur member, and is positioned closer to a surface of the transfer material than the plane. 13. The image forming apparatus according to claim 12, wherein the second spur member has at least three protrusions. 14. A first image carrying means for carrying a toner image formed by a toner image forming means, and a toner image carried by said first image carrying means is transferred. While supported on the surface,
A second image carrying means for conveying a transfer material; and a second image carrying means for carrying the toner image carried by the first image carrying means to the second image carrying means.
A first transfer unit that transfers the image on the surface of the transfer material, or a second transfer unit that transfers the toner image carried on the second image support onto the back surface of the transfer material; An image forming apparatus having a fixing unit for fixing a toner image transferred to a transfer material, wherein a claw member is arranged between the second image bearing unit and the fixing unit in order from an upstream side in a conveying direction of the transfer material. And a first spur member that is rotatable and has a plurality of protrusions on the peripheral surface and a second spur member that is rotatable and has a plurality of protrusions on the peripheral surface, respectively, A plurality of claws are provided in a direction orthogonal to the direction, and the claw member and a first spur member supporting member that supports the first spur member are integrally formed, and a side of the claw member where the transfer material comes into contact is provided. The surface has a concave shape curved toward the back side of the transfer material. An image forming apparatus characterized by.