JPH10254254A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent soiling with toner of a transfer material electrifying means by providing an interlocking mechanism for releasing the abutting of the transfer material electrifying means, in accordance with the release of the abutting of a cleaning means for a second image carrying means. SOLUTION: A toner image receptor cleaning blade 241 as the cleaning means for the second image carrying means is provided to face a driven roller 14e across a toner image receptor 14a as the second image carrying means and can be abutted on the toner image receptor 14a or released in abutting by using a supporting shaft 242 as a rotary supporting point. The cleaning blade 241 is abutted on the toner image receptor 14a, to clean it. A leveling member 261 is linked with the toner image receptor cleaning blade, to level a toner puddle remaining on the receptor 14a, at the time of releasing the abutting of the cleaning blade 241. The leveled toner passes through the gap between a paper electrifying brush 271 and the receptor 14a. Therefore, the soiling with the toner of the paper electrifying brush 271 caused by the toner puddle remaining on the receptor 14a is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotography in which a toner image formed on an image carrier (photosensitive drum) is transferred and fixed onto a transfer material to form an image in a copying machine, a printer, a facsimile or the like. The image forming apparatus of the type, in particular, by transferring the toner image on the image carrier to the front surface of the transfer material or once on the toner image receiver and then to the back surface of the transfer material, Also, the present invention relates to an image forming apparatus capable of forming an image.

[0002]

2. Description of the Related Art Conventionally, in double-sided image formation, an image on one side formed on an image carrier (photosensitive drum) is transferred and fixed on a transfer material, and is temporarily stored in a double-sided reversing sheet feeding device. Then, a transfer material is fed from the double-sided reversing sheet feeding device in synchronization with the image formed on the image carrier again, and the image is transferred and fixed on the other surface of 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 paper feeder or passing through the fixing device twice is performed, so that the transfer material transfer reliability is low.
It was the cause of jams. In contrast,
JP-B-49-37538, JP-B-54-2874
0, JP-A-1-44457 and JP-A-4-2
Japanese Patent Application Laid-Open Nos. 14576/1994 and the like propose a method in which a toner image is formed on both surfaces of a transfer material and then fixed once, and in particular, an image carrier is disclosed in JP-A-1-44457 and JP-A-4-214576. A method has been proposed in which a plurality of sets of image forming means including a charging means, an image writing means, a developing means and the like are arranged in parallel on a toner image receiving body to form a double-sided copy of a color image.

[0004]

However, Japanese Patent Application Laid-Open Nos. Hei 1-44457 and Hei 4-214576 mentioned above.
In the double-sided color image formation proposed in Japanese Patent Application Laid-Open Publication No. H08-27, the transferability of the transfer material is improved, but the color toner images are superimposed one by one on the toner image receiver, so that color misregistration, toner scattering and rubbing, etc. Image degradation easily occurs.

On the other hand, as shown in FIG. 11, the present inventors temporarily transfer the toner image formed on the first image holding means (photosensitive drum) 910 to the second image holding means (toner image receiving member). ) 914a, and collectively transfer them to the photosensitive drum 9 again.
10, a toner image formed on the toner image receiver 914a and a toner image formed again on the photosensitive drum 910 are transferred to both sides of the recording paper (transfer material) P. doing.

At this time, a second image carrier cleaning means (toner image receiver cleaning blade) 941 is provided opposite to the toner image receiver 914a, and the toner image receiver 91 is moved by the toner image receiver cleaning blade 941.
4a, the toner remaining after transfer on the toner image receiving member 9a is cleaned.
When the toner image is released from the toner image receiving member 14a, a toner pool remains on the toner image receiving member 914a, and the recording paper P is charged, and the recording paper P is attracted to the toner image receiving member 914a and conveyed over the toner image receiving member (paper charging means (paper charging)). The brush 971 has toner attached thereto, soiling the paper charging brush 971, deteriorating the adhesion of the recording paper P to the toner image receiving member 914a, and deteriorating the transportability.

The present invention solves the above-mentioned problem and reduces the amount of toner remaining on the second image bearing means when the second image bearing means cleaning means is released from contact with the second image bearing means. It is an object of the present invention to provide an image forming apparatus in which toner contamination of a transfer material charging unit is prevented.

[0008]

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 holding means for holding the transferred toner image on the surface, a first transfer means for transferring the toner image carried on the first image holding means to a surface of a transfer material, An image forming apparatus comprising: a second transfer unit configured to transfer a toner image carried by a second image carrying unit to a back surface of the transfer material; and a fixing unit configured to fix the toner images transferred to both surfaces of the transfer material. In the apparatus, a second image carrying means cleaning means capable of contacting and releasing contact with the second image carrying means, and a second image carrying means of the second image carrying means cleaning means. Downstream of the second in the rotational direction.
Transfer material charging means for contacting the image bearing means and adsorbing the transfer material to the second image bearing means, and the transfer material charging means as the second image bearing means cleaning means releases the contact. The first aspect of the present invention is achieved by an image forming apparatus having an interlocking mechanism for releasing the contact.

The above object is also achieved by a first image holding means for holding a toner image formed by a toner image forming means,
A second image carrier for transferring the toner image carried on the first image carrier, and carrying the transferred toner image on the surface; and a toner image carried on the first image carrier. Transfer means for transferring a toner image carried by the second image carrying means to the back surface of the transfer material, and first and second transfer means for transferring the toner image carried by the second image carrying means to the back surface of the transfer material. An image forming apparatus having a fixing unit for fixing the toner image transferred to the second image holding unit; a second image holding unit cleaning unit capable of abutting and releasing the second image holding unit facing the second image holding unit; And a transfer material charging means for contacting the second image bearing means with the second image bearing means and adsorbing the transfer material to the second image bearing means in the rotation direction of the second image bearing means of the second image bearing means cleaning means. Wherein said second image bearing means cleaning means is provided. The image forming method according to claim 1, further comprising inserting a separating member for separating the transfer material charging means from the second image bearing means as the contact is released, between the second image bearing means and the transfer material charging means. This is achieved by a device (second invention).

[0010]

Embodiments of the present invention will be described below. The description of the present application does not limit the technical scope of the claims and the meaning of terms. Also, the following assertive description in the embodiment of the present invention indicates the best mode, and does not limit the meaning of the terms of the present invention or the technical scope. In the following description of the embodiment, when a color toner image is transferred to a transfer material, the transfer is performed on the surface of the transfer material facing the first image carrying means in the transfer area (referred to as the surface of the transfer material). The image to be transferred is referred to as a front image, and the image transferred to the other surface of the transfer material (referred to as the back surface of the transfer material) is referred to as a back image. Further, in the following image forming apparatus, copying on one side only by the first image bearing means or the second image bearing means can be performed. The operation of contact or release of the second transfer means cleaning means, the leveling member, the transfer material charging means, the separation member, and the like is performed by the operation of levers, cams, and the like provided on both side ends or one side of the apparatus main body. Done.

An image forming process and each mechanism of an embodiment of the image forming apparatus according to the present invention will be described with reference to FIGS. 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. 3A is a diagram showing a state in which toner images are formed on both surfaces of the image forming apparatus according to the present invention, and FIG.
FIG. 3B is a diagram in which the toner image formed on the image carrying means is transferred onto a second image carrying means to form a back image, and FIG.
FIG. 3C is a diagram illustrating the formation of a front surface image on the first image holding unit in synchronization with the back side image on the second image holding unit. FIG. 3C is a diagram illustrating the formation of a double-sided image on a transfer material. , FIG. 4 shows the second
5 is a timing chart showing the contact timing of the image carrier cleaning means, the transfer material charging means and the leveling member.

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 holding means, 14c a transfer device as a first transfer means, 14g a backside transfer device as a second transfer means, and 271 a paper charging means as a transfer material charging means. A brush 14 h, a paper separation AC static eliminator as a transfer material separating unit, 160 a conveying unit, 17 a fixing device as a fixing unit, 241 a toner image receiver cleaning blade as a second image carrying unit cleaning unit, 261 Is a leveling member.

Photosensitive drum 10 as first image bearing means
Is obtained 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, for example, a transparent member made of optical glass or transparent acrylic resin. With the conductive layer grounded, it is rotated clockwise as indicated by the arrow in FIG.

The photosensitive drum 10, as shown in FIG.
Flange members 10a and 1 on both sides for engaging and fixing it
0b is rotatably supported by the bearings B1 and B2 fitted in the flange members 10a and 10b at both ends with respect to the drum shaft 30 erected and fixed to the apparatus main body, and is rotatably supported. Is driven in mesh with a drive gear (not shown) on the apparatus body side to rotate at a constant speed in a predetermined direction. Reference numeral 12A denotes a lead wire from a light emitting element (LED) of an image exposure unit described later.

In the present embodiment, 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, have one unit. Four sets are provided for the image forming processes of yellow (Y), magenta (M), cyan (C), and black (K) in the rotation direction of the photosensitive drum 10 indicated by the arrow in FIG. On the other hand, Y, M, C,
They are arranged in the order of 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. Each exposure optical system 12
Is a linear exposure element 12a 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 axis of the photosensitive drum 10 are arranged in an array.
And a light converging light transmitter (trade name: Selfoc lens array) 12b as an imaging element
The exposure unit is configured to be attached to the holding member 20. In addition to the exposure optical system 12 for each color, a uniform exposure device 12e and a simultaneous transfer exposure device 12d are attached to the holding member 20, and the photosensitive drum 10 is integrally formed.
Of the substrate. The exposure optical system 12 for each color is
The photosensitive layer of the photosensitive drum 10 is image-exposed from the back surface in accordance with image data of each color read by a separate image reading device and stored in the memory, and an electrostatic latent image is formed on the photosensitive drum 10. As the exposure element 12a, other FL
(Phosphor emission), EL (electroluminescence),
It is also possible to use a plurality of light emitting elements such as PL (plasma discharge) arranged in an array. 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 the Y, M, and C toners. In this embodiment, the image exposure is performed from the back. Since it is a system, the wavelength may be shorter than 400 to 780 nm, which does not have sufficient transparency to the color toner.

The developing device 13 as a developing means for each color keeps a predetermined gap with respect to the peripheral surface of the photosensitive drum 10 and rotates in a forward direction with respect to the rotating direction of the photosensitive drum 10, for example, 0.5 to 1 mm in thickness. , A developing sleeve 131 formed of a non-magnetic stainless steel or aluminum material having an 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 a conductive material dispersed in an engineering plastic such as a modified polyimide, a thermosetting polyimide, an ethylene tetrafluoroethylene copolymer, a polyvinylidene fluoride, and a nylon alloy, and has a thickness of 0.1 to 1.0 m.
m, surface resistivity 10 ⁶ -10 ¹³ Ω, volume resistivity 10 ⁸ -1
This is a seamless belt of a two-layer structure in which a fluorine coating having a thickness of 5 to 50 μm is applied as a toner filming preventing layer to the outside of a film of a semiconductive substrate of 0 ¹⁴ Ω · cm. In addition to the above, as a base of the belt, a conductive material dispersed in silicon rubber or urethane rubber or the like is used.
A semiconductive rubber belt of ~ 2.0 mm can also be used. The toner image receiver 14a is stretched between a driving roller 14d and a driven roller 14e, and is rotated in a counterclockwise direction indicated by an arrow in FIG.

A transfer device 14c, which is a first transfer means, is provided opposite to the photosensitive drum 10 with the toner image receiver 14a interposed therebetween.
The transfer area 14b is formed between the steps. A DC voltage having a polarity opposite to that of the toner (positive polarity in the present embodiment) is applied to the transfer device 14c, and a transfer electric field is formed in the transfer area 14b, so that the toner image on the photosensitive drum 10 is transferred to the toner image receiving member. Transfer onto 14a or onto the surface of the transfer material.

A back transfer unit 14g, which is a second transfer unit, is provided to face the drive roller 14d with the toner image receiving member 14a interposed therebetween, and a DC voltage having the opposite polarity (positive polarity in the present embodiment) to the toner is applied. The toner image on the toner image receiving member 14a is transferred to the back surface of the transfer material.

Paper charging brush 271 as transfer material charging means
Is provided so as to face the grounded driven roller 14e, and is normally in contact with the toner image receiver 14a. The toner image receiver cleaning blade 241 is provided by a mechanism described later.
Image receiving member cleaning blade 2 at the time of release of contact
In conjunction with 41, it is rotated about the support shaft 272 as a rotation fulcrum, and is temporarily released from the toner image receiver 14a. The paper charging brush 271 having a brush-like tip is normally brought into contact with the toner image receiver 14a, and when the recording paper P passes, the direct current of the same polarity as the toner (in this embodiment, a negative polarity) is applied to the paper charging brush 271. A voltage is applied to the paper charging brush 271
As a result, the recording paper P is charged to the same polarity as the toner, is attracted to the toner image receiver 14a, and is fed to the transfer area 14b.

Paper separation AC neutralizer 1 as transfer material separating means
Reference numeral 4h is provided at the end of the toner image receiving member 14a on the fixing device 17 side, and if necessary, an AC voltage on which a DC voltage having the same polarity or opposite polarity to the toner is superimposed is applied.
The transfer material conveyed by 4a is separated.

The transport section 160 is provided between the toner image receiver 14a and the fixing device 17, and a spur 162 is provided on the upper surface of the transport section 160. The spur 162 prevents the rear toner image of the transfer material conveyed by the toner image receiver 14 a from being disturbed, and conveys the transfer material to the fixing device 17.

The fixing device 17 as a fixing means is composed of two rollers, a fixing roller 17a having a heater inside both rollers and a pressure roller 17b.
The toner image on the transfer material is fixed by applying heat and pressure between the transfer roller 7a and the pressure roller 17b.

A toner image receiver cleaning blade 241 serving as a second image carrier cleaning means is provided to face the driven roller 14e with the toner image receiver 14a interposed therebetween, and the toner image receiver is supported on a support shaft 242 as a rotation fulcrum. 14
a can be brought into contact with and released from the toner image receiving member 14.
a, and the toner image receiving member 14a is cleaned.

The leveling member 261 is, for example, a rectangular flat plate member having a thickness of about 0.3 to 1 mm using a rubber material, and is provided in parallel with the driven roller 14e which is grounded.
Normally, the contact state of the toner image receiver 14a is released, but when the contact of the toner image receiver cleaning blade 241 is released by a mechanism to be described later, the toner image receiver is temporarily interlocked with the toner image receiver cleaning blade 241. Body 14
a, one end of the flat plate member is in contact with the toner image receiving member 1 when the contact of the toner image receiving member cleaning blade 241 is released.
4a to level the remaining toner.

Next, the image forming process will be described.

The photosensitive drum 10 is rotated clockwise as indicated by an arrow in FIG. 1 by the start of a photosensitive member drive motor (not shown) at the start of image recording, and at the same time, yellow (Y) disposed on the left side of the photosensitive drum 10. The application of a potential to the photosensitive drum 10 is started by the charging operation of the scorotron charger 11).

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

The latent image is reversal-developed in a non-contact state by the Y developing device 13 to form a yellow (Y) toner image in accordance with the rotation of the photosensitive drum 10.

Next, the photosensitive drum 10 is mounted on the Y developing device 1.
A potential is applied to the Y toner image by the charging action of the magenta (M) scorotron charger 11 disposed above the third color signal 3, and a second color signal, that is, M image data is converted by the M exposure optical system 12. Image writing is performed by the corresponding electric signal, and magenta (M) is formed on the yellow (Y) toner image by non-contact reversal development by the M developing unit 13.
Are formed in a superimposed manner.

By the same process, the photosensitive drum 10
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 arranged on the right side of FIG. The black (K) toner image corresponding to the fourth color signal is sequentially superimposed thereon by the black (K) scorotron charger 11, the K exposure optical system 12, and the K developing device 13. Formed, the photosensitive drum 10
Within one rotation, a superimposed four color toner image of yellow (Y), magenta (M), cyan (C) and black (K) is formed on the peripheral surface (toner image forming means).

The 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 transparent 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 image forming process, is transferred to the transfer device as the first transfer means in the transfer area 14b. Due to the transfer electric field formed by the toner image receiving member 14c and the toner image receiving member 14a, which is a second image carrying means provided in proximity to or in contact with the photosensitive drum 10, the toner image is transferred collectively (FIG. 3).
(A)). At this time, uniform exposure is performed by the simultaneous transfer exposure device 12d provided inside the photosensitive 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 charge removal by the photosensitive drum AC charge remover 16, the toner is transferred to a cleaning device 19 as first image carrier cleaning means, or is exposed to light. The cleaning is performed by a cleaning blade 19a made of a rubber material in contact with the body drum 10, and further, in order to eliminate the history of the photoconductor in the previous image formation, for example, exposure by a uniform exposure unit 12e before charging using a light emitting diode is performed. As a result, the peripheral surface of the photoreceptor is neutralized, and a superimposed color toner image, which subsequently becomes a surface image, is formed in the same manner as in the above-described color image forming process (FIG. 3B). At this time, the surface image formed on the photosensitive drum 10 is
The image data is changed so as to be a mirror image with respect to the back side image formed on the top of the image.

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 carried 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, a DC voltage of the same polarity as that of the toner (in this embodiment, a negative polarity) is applied to the paper charging brush 271 as a transfer material charging unit brought into contact with the recording paper P, and the paper charging brush is charged. By 271, the recording paper P is charged with the same polarity as the toner, is attracted to the toner image receiver 14 a, and is fed to the transfer area 14 b. 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. The voltage applied to the paper charging brush 271 is cut off immediately before or at the same time as the paper charging brush 271 passes the rear end of the recording paper P.

Further, as the transfer material charging means, a conductive roller to which a DC voltage having the same polarity as that of the toner is applied, a semiconductive film member or a blade member may be used.

In the transfer area 14b, the first voltage to which a voltage having a polarity opposite to that of the toner (positive in this embodiment) is applied.
The surface image on the photosensitive drum 10 is collectively transferred to the upper surface side (front surface side) of the recording paper P by the transfer device 14c as a transfer unit. 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 transfer unit 14c, uniform exposure is performed by a simultaneous transfer exposure unit 12d using, for example, a light-emitting diode, provided inside the photosensitive drum 10 so as to perform good transfer so as to face the transfer area 14b. May be performed.

Next, a backside image on the peripheral surface of the toner image receiver 14a is collectively collected by a backside transfer unit 14g as a second transfer unit to which a voltage having a polarity opposite to that of the toner (positive polarity in this embodiment) is applied. Then, the image is transferred to the lower surface side (back surface side) of the recording paper P (FIG. 3C).

Since the toner images of the respective colors overlap with each other, it is preferable that the toner in the upper layer and the toner in the lower layer of the toner layer are charged to the same polarity with the same charge amount in order to enable batch transfer. Accordingly, in the double-sided image formation in which the polarity of the color toner image formed on the toner image receiving body 14a is inverted by corona charging or the polarity of the color toner image formed on the photosensitive drum 10 is inverted by corona charging, Since the toner of the lower layer is not sufficiently charged to the same polarity, the transfer becomes unfavorable.

The reversal development is repeated on the photosensitive drum 10, and the color toner images of the same polarity formed by superimposition are collectively transferred to the toner image receiving member 14a without changing the polarity, and then recorded without changing the polarity. Batch transfer to paper P is preferable because it contributes to improving the transferability of backside image formation. Also for the surface image formation, reversal development is repeatedly performed on the photosensitive drum 10 to collectively transfer color toner images of the same polarity formed by superimposition onto the recording paper P without changing the polarity.
It is preferable because it contributes to improvement of the transferability of surface image formation.

From the above, in the color image formation, the first transfer means is operated to form a color toner image on the surface of the transfer material by using the above-described image forming method for the front surface and the back surface. A two-sided image forming method of forming a color toner image on the back surface of the transfer material by operating the second transfer means is preferably employed.

The recording paper P on which the color toner images are formed on both sides is subjected to a paper separation AC neutralizer 14h as a transfer material separating means.
, Is separated from the toner image receiving body 14a, is conveyed to the fixing device 17 via the conveying unit 160 provided with a spur 162, and heat and pressure are generated between the fixing roller 17a and the pressure roller 17b. By the addition, the toner image on the recording paper P is fixed, and the recording paper P on which double-sided image recording has been performed is sent with the front and back images reversed, and is discharged by a discharge roller 18 to a tray outside the apparatus.

The toner remaining on the peripheral surface of the toner image receiver 14a after the transfer is cleaned by a toner image receiver cleaning blade 241 as a second image carrier cleaning means.

The toner remaining on the peripheral surface of the photosensitive drum 10 after the transfer is discharged by a photosensitive drum AC static eliminator 16 and then enters a cleaning device 19 or a cleaning device 19 by a cleaning blade 19a.
And is collected by a screw 19b in a waste toner container (not shown). The photosensitive drum 10 from which the residual toner has been removed by the cleaning device 19 is uniformly charged by the Y scorotron charger 11, and enters the next image forming cycle.

Since the superposed 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.

In the double-sided image formation, as shown in FIGS. 3 and 4, the back side image formed on the photosensitive drum 10 is in contact with the toner image receiving body 14a while the image is being transferred to the toner image receiving body 14a. (FIG. 3A) The toner image receiver cleaning blade 241 releases the contact before the toner image of the back surface image on the toner image receiver 14a passes through the position of the toner image receiver cleaning blade 241. 3
(B)) Immediately after passing through, the toner image receiving member 14a comes into contact with the toner image receiving member 14a (FIG. 3 (C)), and the transfer residual toner image of the back surface image corresponding to the previous print is removed.
3A (FIG. 3A), immediately after the rear end of the transfer residual toner image of the back side image has passed the position of the toner image receiver cleaning blade 241 and before the front end of the toner image of the next back side image comes. Then, the contact with the toner image receiving body 14a is released (FIG. 3B). Further, the paper charging brush 271 is always in contact with the toner image receiver 14a, and the leveling member 261 is always in contact with the toner image receiver 14a.
As described below, when the contact of the toner image receiver cleaning blade 241 is released, the leveling member 261 is temporarily brought into contact with the toner image receiver 14a in conjunction with the release operation of the toner image receiver cleaning blade 241. The paper charging brush 271 is temporarily brought into contact with the toner image receiving member 14.
a and the contact release state.

The leveling member 261 and the paper charging brush 271
The temporary movement of the toner image receiving member cleaning blade 2
When the toner accumulated in the toner image receiving member 41 is released from contact with the cleaning blade 241 of the toner image receiving member, the toner solidifies (toner accumulation) and moves while adhering to the toner image receiving member 14a.
This is to prevent the paper charging brush 271 from being stained.

The leveling member 261 and the paper charging brush 27
In the movement timing of No. 1, after the transfer-backed toner image on the back side passes the position of the cleaning blade 241 of the toner image receiver, it moves together with the release of the cleaning blade 241 of the toner image receiver, and then the passage of the toner image of the subsequent back side image Previously, the smoothing member 261 has been released from the contact, the paper charging brush 271 has been released from the contact, and the toner image receiver cleaning blade 241 has been released from the contact.

One embodiment of a mechanism for contacting and releasing contact of the leveling member and transfer material charging means in conjunction with release of contact of the second image bearing means cleaning means will be described with reference to FIGS. I do. FIG. 5 is a view showing an embodiment of a leveling member and a mechanism for contacting and releasing contact of the transfer material charging means in conjunction with release of contact of the second image carrier cleaning means. FIG. FIG. 7 is a diagram showing a contact state of the leveling member of FIG. 5, FIG. 7 is a diagram showing a contact release state of the transfer material charging unit of FIG. 5, and FIG. It is a figure which shows the contact release state of.

According to FIG. 5, the toner image receiving member cleaning blade 24 provided opposite to the driven roller 14e.
Numeral 1 is attached to a lever 243, is rotatable about a support shaft 242, is urged to rotate counterclockwise by a spring 245, and comes into contact with the toner image receiver 14a. 243
Reference numeral a denotes a tip portion provided on the toner image receiver cleaning blade 241 side of the lever 243, and a pin 244 is provided on an end portion of the lever 243 opposite to the toner image receiver cleaning blade 241. Reference numeral 251 denotes an eccentric cam rotated by a support shaft 252 by a motor (not shown), and the lowest position a of the eccentric cam 251 is opposed to the pin 244 with a slight gap in a state where the cleaning blade 241 of the toner image receiving member is in contact with the eccentric cam.

The leveling member 261 is attached to a circular plate member 263 which is rotatable about a support shaft 262 and is rotatable. Reference numeral 265 denotes two pins 264 a and 264 provided at the end of the plate member 263 on the opposite side to the leveling member 261.
b, and the leveling member 261 is kept at a neutral point separated (released) from the toner image receiver 14a by the elasticity of the leaf spring 265. A projection 263a is provided on the tip 243a side of the circular plate member 263. When the leveling members 261 are separated from each other, the protrusions 263a
Is provided with a predetermined gap from the tip 243a.

Reference numeral 277 denotes a support shaft 26 coaxial with the leveling member 261.
2 is a lever rotatable around a fulcrum, and a lever 277
Is provided with a protruding portion 277a on the tip portion 243a side and a long groove 277b on the opposite side. When the paper charging brush 271 is in contact with the toner image receiving member 14a due to the elasticity of a leaf spring 275 described later, the protrusion 27
7a is provided with a predetermined gap larger than the gap between the tip 243a and the protrusion 263a.

The paper charging brush 271 is attached to one end of a U-shaped lever 273 which is rotatable around a support shaft 272 and is rotatable. A pin 276 is provided at the other end of the lever 273. Two pins 274a and 274b are provided at the base of the C-shaped lever 273, and the paper charging brush 271 is light, for example, about 1 to 10 gr by the elasticity of a leaf spring 275 sandwiched between the two pins 274a and 274b. It comes into contact with the toner image receiver 14a by force. Also,
In this state, the lever 277 causes the protrusion 277a to move to the tip 243a by the long groove 277b engaged with the pin 276.
And the predetermined gap is maintained.

According to FIG. 6, when the contact of the toner image receptor cleaning blade 241 is released, the motor (not shown) performs eccentricity based on the timing of releasing the contact of the toner image receptor cleaning blade 241 described with reference to FIG. The cam 251 is rotated clockwise, the pin 244 of the lever 243 is pushed up by the end face of the eccentric cam 251 against the elasticity of the spring 245, and the lever 243 is rotated clockwise, so that the toner image receptor cleaning blade 241 is rotated. Are released from the toner image receiving member 14a.

Toner image receiver cleaning blade 24
With the release of the abutment 1, the distal end portion 243a of the lever 243 presses the protruding portion 263a of the circular plate member 263 to rotate, and the plate member 263 moves against the support shaft 2 against the elasticity of the plate spring 265.
The leveling member 261 is rotated counterclockwise around the fulcrum 62 and the leveling member 261 provided integrally with the plate member 263 is
4a. When the contact of the toner image receiver cleaning blade 241 is released, the remaining toner on the toner image receiver 14a is leveled by the leveling member 261 brought into contact with the toner image receiver 14a.

According to FIG. 7, the eccentric cam 251 is further rotated clockwise, and the pin 2
44 is pressed, and the lever 243 of the toner image receiver cleaning blade 241 is rotated clockwise. The tip 243 a of the lever 243 is connected to the protrusion 277 of the lever 277.
a, the lever 277 is turned about the support shaft 262 as a fulcrum, and the lever 273 is rotated clockwise about the support shaft 272 as a fulcrum against the elasticity of the leaf spring 275 via a pin 276 engaged with the long groove 277b. Then, the paper charging brush 271 is released from contact with the toner image receiver 14a.

The toner leveled by the leveling member 261 described with reference to FIG. 6 passes through the gap between the paper charging brush 271 and the toner image receiver 14a separated from the toner image receiver 14a. Therefore, toner contamination of the transfer material charging means due to the accumulation of toner remaining in the second image bearing means is prevented.

According to FIG. 8, the eccentric cam 251 is further rotated clockwise, and the pin 24 is rotated by the end face of the eccentric cam 251.
4 is pressed, and the toner image receptor cleaning blade 2
41 lever 243 is rotated clockwise. When the pin 244 is rotated to the highest position b of the eccentric cam 251, the tip 243 a of the lever 243 is connected to the projection 263 a of the plate member 263 to which the leveling member 261 is attached, and the long groove 277.
b, the lever 273 is rotated via the pin 276 and the paper charging brush 271 is disengaged from the projection 277a of the lever 277 that has separated the toner charging member 14a from the toner image receiving member 14a. As shown in FIG. The leveling member 261 is released from contact with the toner image receiver 14a by the elasticity of the spring 265 and is separated from the toner image receiver 14a, and the paper charging brush 271 is in contact with the toner image receiver 14a by the elasticity of the leaf spring 275. State.

The motor (not shown) is stopped in a state where the contact of the cleaning blade 241 of the toner image receiver shown in FIG. 8 is released, and the released state is maintained. At the contact timing, a motor (not shown) is instantaneously driven, and the eccentric cam 251 is driven.
The eccentric cam 251 is instantaneously rotated to the lowest position a having a gap from the highest position b where the pin 244 contacts the pin 244, and the toner image receiver cleaning blade 241 returns to the contact state shown in FIG.

At this time, the tip 243a of the lever 243 of the toner image receptor cleaning blade 241 is
45 is rotated counterclockwise by the suction force of the plate spring 26.
The projection 263a and the projection 277a are rotated clockwise in a direction opposite to the rotation direction when the contact is released, and the projection 263a and the projection 277a are rotated in the clockwise direction against the leaf spring 275. Are pushed back and turned, and the cleaning blade 241 of the toner image receiver is brought into contact.

FIGS. 9 and 10 show another example of the contact release mechanism of the transfer material charging means. FIG. 9 is a view showing a separation mechanism of the transfer material charging means, and FIG. 10 is a view showing the separation member of FIG.

According to FIG. 9, the toner image receiving member cleaning blade 2 is driven by the same mechanism as described in FIG.
41 receives an urging force in the counterclockwise direction by the elastic force of the spring 245, and comes into contact with the toner image receiving body 14a.
1 is maintained at a neutral point separated (released) from the toner image receiver 14a by the elasticity of the leaf spring 265.

The paper charging brush 271 is rotatable about a support shaft 272, and receives an urging force in a counterclockwise direction by a spring 273 so that the tip of the paper charging brush 271 is brought into contact with the toner image receiving member 14a.

As shown in FIG. 10, reference numeral 391 is a rectangular plate-shaped separating member, which is provided with pins 391a on both side ends, and spacers 392 on both sides on the lower surface (on the side of the toner image receiver 14a in FIG. 9). Is provided. 393 is the separating member 3
This is a guide rail for guiding the slide 91.

Reference numeral 283 denotes a support shaft 26 coaxial with the leveling member 261.
2 is a lever that can rotate around a fulcrum,
Is provided with a protrusion 283a on the tip 243a side of the lever 243 of the toner image receiver cleaning blade 241 and a long groove 283b on the opposite side.

The pin 391a of the separating member 391 is engaged with the long groove 283b of the lever 283, and the two pins 284 provided at the end further than the long groove 283b of the lever 283.
The separation member 391 on the guide rail 393 is held by the elasticity of the leaf spring 285 sandwiched between the a and 284b. In this state, the end on the spacer 292 side of the separation member 391 is kept at a predetermined interval from the paper charging brush 271.

Toner image receiver cleaning blade 24
6, the eccentric cam 251 is slightly moved from the pin 244 of the lever 243 by a motor (not shown) based on the timing of releasing the contact of the cleaning blade 241 of the toner image receiver in the same manner as described with reference to FIG. The eccentric cam 251 is rotated clockwise from the separated minimum position a.
The rotation of the pin 244 of the lever 243 causes the eccentric cam 25
1 is pushed up against the elasticity of the spring 245,
The lever 243 is rotated clockwise, and the contact of the toner image receiver cleaning blade 241 with the toner image receiver 14a is released. At this time, the tip 2 of the lever 243
43a is a circular plate member 2 as described in the above example.
63 is rotated counterclockwise, and the plate member 2 is rotated.
The leveling member 261 provided integrally with the abutment 63 is brought into contact with the toner image receiver 14a, and the toner accumulation when the toner image receiver cleaning blade 241 is released is leveled.

Further, when the eccentric cam 251 is rotated clockwise, the protrusion 283a is rotated counterclockwise by the tip 243a, and the lever 283 is pressed against the elasticity of the leaf spring 285.
Is rotated counterclockwise, the separating member 391 is slid on the guide rail 393 by the pin 391a engaging with the long groove 283b, and is moved in the direction of the paper charging brush 271 indicated by the arrow in FIG. The paper charging brush 271 is inserted into both ends of the toner image receiver 14a and is separated from the toner image receiver 14a. Therefore, toner contamination of the transfer material charging means due to the accumulation of toner remaining in the second image bearing means is prevented.

As described with reference to FIG.
When a pushes over the projections 263a and 283a and gets over it,
The leveling member 261 is returned from the toner image receiving member 14 a to the state of being released from contact by the elasticity of the leaf spring 265, and the separating member 391 is charged by the elasticity of the leaf spring 285 to the paper charging brush 271.
The state returns to the contact release state with a longer interval. In this state, the eccentric cam 251 is maintained at the highest position b as described with reference to FIG. 8, and the toner image receiver cleaning blade 241 is maintained at the position where the contact with the toner image receiver 14a is released. .

Toner image receiver cleaning blade 24
At the time of abutment for cleaning the toner image receiver 14a, the eccentric cam 2 is driven by a motor (not shown).
8, the eccentric cam 251 is instantaneously rotated to the lowest position a having a gap from the highest position b where the position of the eccentric cam 251 contacts the pin 244, as described with reference to FIG. The body cleaning blade 241 returns to the contact state in FIG.

[0074]

According to the present invention, when the contact of the cleaning means with the second image bearing means is released, toner contamination of the transfer material charging means due to the accumulation of toner remaining in the second image bearing means is prevented.

[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 state where toner images are formed on both surfaces of the image forming apparatus according to the present invention.

FIG. 4 is a timing chart showing a contact timing between a second image carrier cleaning unit, a transfer material charging unit, and a leveling member.

FIG. 5 is a diagram showing an embodiment of a mechanism for contacting and releasing contact of a leveling member and transfer material charging means in conjunction with release of contact of a second image carrier cleaning means.

FIG. 6 is a view showing a contact state of the leveling member of FIG. 5;

FIG. 7 is a view showing a state in which the transfer material charging unit in FIG. 5 is released from contact.

FIG. 8 is a diagram illustrating a contact release state of a second image carrier cleaning unit.

FIG. 9 is a diagram illustrating a separation mechanism of a transfer material charging unit.

FIG. 10 is a view showing a separating member of FIG. 9;

FIG. 11 is a diagram showing a conventional problem.

[Explanation of symbols]

 Reference Signs List 10 photoreceptor drum 11 scorotron charger 12 exposure optical system 13 developing device 14a toner image receiver 14c transfer device 14g backside transfer device 17 fixing device 241 toner image receiver cleaning blade 261 leveling member 271 paper charging brush 391 separating member P recording paper

Continued on the front page (72) Kunio Shigeta, Inventor Konica Co., Ltd. 2970 Ishikawacho, Hachioji-shi, Tokyo

Claims (5)

[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. A second image carrying means carried on the surface; a first transferring means for transferring the toner image carried on the first image carrying means onto a surface of the transfer material; and a carrying means carried on the second image carrying means. An image forming apparatus comprising: a second transfer unit configured to transfer the toner image transferred to the back surface of the transfer material; and a fixing unit configured to fix the toner image transferred to both surfaces of the transfer material. A second image carrying means cleaning means capable of contacting and releasing contact with the carrying means; and a second image carrying means cleaning means downstream of the second image carrying means in the rotation direction of the second image carrying means. The transfer material is brought into contact with the image carrying means and A transfer material charging means for adsorbing to the image bearing means, and an interlocking mechanism for releasing the contact of the transfer material charging means as the second image bearing means cleaning means releases the contact. Forming equipment. 2. The cleaning device according to claim 1, wherein said cleaning means is disposed at a position downstream of said second image bearing means in a rotational direction of said second image bearing means and upstream of said transfer material charging means. The image forming apparatus according to claim 1, further comprising a leveling member that contacts the second image bearing unit. 3. 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. A second image carrying means carried on the surface; a first transferring means for transferring the toner image carried on the first image carrying means onto a surface of the transfer material; and a carrying means carried on the second image carrying means. An image forming apparatus comprising: a second transfer unit configured to transfer the toner image transferred to the back surface of the transfer material; and a fixing unit configured to fix the toner image transferred to both surfaces of the transfer material. A second image carrying means cleaning means capable of contacting and releasing contact with the carrying means; and a second image carrying means cleaning means downstream of the second image carrying means in the rotation direction of the second image carrying means. The transfer material is brought into contact with the image carrying means and A transfer member charging unit for adsorbing the image holding unit; and a separating member for separating the transfer material charging unit from the second image holding unit as the second image holding unit cleaning unit releases contact. An image forming apparatus which is inserted between a second image bearing means and the transfer material charging means. 4. The cleaning device according to claim 1, wherein said cleaning means is disposed at a position downstream of said second image bearing means in a rotational direction of said second image bearing means and upstream of said transfer material charging means. The image forming apparatus according to claim 3, further comprising a leveling member that contacts the second image bearing unit. 5. The image forming apparatus according to claim 3, wherein the movement of the separation member is interlocked with the cleaning of the second image carrier.