JPH09305089A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To intercept heat from a fixing device to a 2nd image carrier, to reduce the deterioration and the decomposition of the 2nd image carrier and to maintain an excellent double-sided image over a long term by providing a discharging means for discharging outside air flowing into a main body to the outside of an image forming device from a transfer material ejection side. SOLUTION: A ventilating fan F1 functioning as the air flow discharging means is provided at the upper part or the side part of the fixing device 17 on the recording paper ejection side of the image forming device. By the rotation of the fan F1, the air inside the image forming device is exhausted through the exhaust holes 101a and 101b of a housing 101 provided on the recording paper ejection side at the side part of the image forming device. By passing through a duct formed by ventilating guide plates 204 and 205 on both side ends in the longitudinal direction of the device 17 by the rotation of the fan F1, the air flow which flows to the upper part crossing between the device 17 and a toner image receiving body 14a from a suction hole 101d provided on the housing 101 at the bottom part of the image forming device main body is formed so as to make the outside air flow in and to discharge the air inside a machine to the outside of the machine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copying machine which arranges a charging means, an image exposing means and a developing means around an image carrier to transfer and fix a toner image formed on the image carrier onto a transfer material. The present invention relates to an electrophotographic image forming apparatus such as a printer, a FAX, or the like.

[0002]

2. Description of the Related Art Conventionally, in double-sided copying, an image on one side formed on an image carrier is transferred and fixed on a transfer material, and this is temporarily stored in a two-sided reversing paper feeder, and the image bearing is again performed. A method has been adopted in which a transfer material is fed from a double-sided reversing sheet feeder in synchronization with an image formed on the body, and an image on the other surface is transferred and fixed onto the transfer material.

In this double-sided copying apparatus, as described above, the transfer of the transfer material, such as feeding to the two-sided reversing paper feeder and passing through the fixing device twice, is performed, so that the reliability of transfer of the transfer material is low. And so on. In contrast, JP-B-49-37538 and JP-B-54-28740.
And JP-A-1-44457 and JP-A-4-21
Japanese Patent Application Laid-Open No. 4576/1994 proposes a method in which a toner image is formed on both surfaces of a transfer material and then fixed once.
JP-A-44457 and JP-A-4-214576 disclose that a plurality of sets of image forming means including an image carrier, a charging means, an image exposing means, a developing means and the like are arranged in parallel on a toner image receiving body. Has been proposed.

[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, the inventors of the present invention once collectively transfer the toner images formed on the image carrier (first image carrier) to the toner image receiver (second image carrier), A double-sided image forming method in which the toner image on the toner image receiving body and the toner image formed on the image bearing body again are transferred to both sides of the transfer material is being examined. However, the toner image receiving body has a maximum image size such as A- Since the size of the toner image receiver becomes long because it can accommodate three sizes, in order to downsize the image forming apparatus, it is necessary to dispose the fixing device for fixing the back side image and the toner image receiver close to each other. Becomes

At this time, the toner image receiving body is heated by the heat from the fixing device to deteriorate or deteriorate the toner image receiving body, or the toner on the toner image receiving body is heated and fused to the toner image receiving body. There is a problem such as doing. In addition, there is a problem that the toner image receiving body is deteriorated or deteriorated by ozone generated by the corona discharger for rear surface transfer or separation which is arranged above the toner image receiving body on the fixing device side.

The present invention solves the above-mentioned problems, heat from the fixing device to the second image bearing means is blocked, deterioration and deterioration of the second image bearing means are alleviated, and back surface transfer is performed. It is an object of the present invention to provide an image forming apparatus in which deterioration and alteration of the second image bearing means due to ozone generated by a corona discharger for use in separation and separation are prevented and a good double-sided image is maintained for a long period of time. And

[0008]

SUMMARY OF THE INVENTION The above-mentioned object is to combine 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 together. Second image carrying means for carrying the transferred toner image on the surface again, and first transfer carrying the toner image carried on the first image carrying means on the surface of the transfer material. Means, a second transfer means for transferring the toner image carried by the second image carrying means to the back surface of the transfer material, and a first transfer means carrying the toner image on the first image carrying means. The toner image formed on the transfer material is transferred to the surface of the transfer material, and the toner image carried on the second image carrying means is transferred to the back surface of the transfer material by the second transfer means. It has a fixing device that fixes the toner image transferred on both sides of In the image forming apparatus, the second image carrier is arranged close to the fixing device, and the outside air that has flowed into the main body of the image forming device passes between the fixing device and the second image carrier. The image forming apparatus is characterized in that the image forming apparatus is provided with an ejecting means for ejecting the transfer material from the ejecting side of the fixing device to the outside of the image forming apparatus (first invention).

Further, the above object is to provide a first image carrying means for carrying the toner image formed by the toner image forming means,
The toner images carried by the first image carrying device are collectively transferred, and the second image carrying device carrying the transferred toner image again on the surface and the first image carrying device are carried. A first transfer means for transferring the toner image on the surface of the transfer material, a second transfer means for transferring the toner image carried by the second image carrying means on the back surface of the transfer material, and The first transfer means transfers the toner image carried by the first image carrying means onto the surface of the transfer material, and the second transfer means carries the toner image carried by the second image carrying means. An image forming apparatus having a fixing device for transferring a toner image on the back surface of the transfer material and fixing the toner images transferred on both surfaces of the transfer material, the outside air flowing into the main body of the image forming apparatus is fixed by the fixing device. A device and a second image bearing means. Is achieved by an image forming apparatus characterized in that a discharge means for discharging to the outside of the image forming apparatus in a direction perpendicular to the discharge direction of the transfer material (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 or 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, an image to be transferred to a surface of the transfer material facing the image carrier in the transfer area (referred to as a surface of the transfer material) will be described. The front image and the image transferred to the other surface of the transfer material (called the back surface of the transfer material) are called the back surface image.

An image forming process of an embodiment of the image forming apparatus of the present invention, each mechanism, and a first example of air flow formation will be described with reference to FIGS. FIG. 1 is a sectional configuration diagram of a color image forming apparatus showing one embodiment of the present invention, FIG. 2 is a side sectional view of the image carrier of FIG.
FIG. 4 is a diagram showing a toner image formation state on both sides, and FIG.
It is a principal part top view which shows the 1st example of airflow formation.

The photosensitive drum 10 serving as an image carrier has, for example, a cylindrical base formed of a transparent member such as optical glass or transparent acrylic resin provided inside, and a transparent conductive layer,
A photosensitive layer such as an a-Si layer or an organic photosensitive layer (OPC) is formed on the outer periphery of the substrate, and is rotated clockwise as shown by an arrow in FIG. 1 in a grounded state.

As shown in FIG. 2, the photosensitive drum 10 has flange members 10a and 10b at both ends for engaging and fixing it.
Is rotatably supported by bearings 110a and 110b fitted in flange members 10a and 10b at both ends of a drum shaft 110 that is erected and fixed to the main body of the apparatus. It is rotated at a constant speed in a predetermined direction by being driven by meshing with a drive gear on the apparatus main body side. A holding member 20 is attached to a drum shaft 110 fixed to both side plates (not shown) of the apparatus main body. The exposure unit 12 for each color is fixed to the holding member 20 and housed inside the base of the photosensitive drum 10.

Scorotron charger 11 as charging means
Is used in the image forming process of each color of yellow (Y), magenta (M), cyan (C), and black (K), and is exposed in a direction orthogonal to the moving direction of the photoconductor drum 10 as an image carrier. A control grid, which is attached to face the body drum 10 and is held at a predetermined potential with respect to the above-described organic photoconductor layer of the photoconductor drum 10, and a discharge electrode 11a that has, for example, a sawtooth electrode and has the same polarity as the toner. Corona discharge causes a charging action (in the present embodiment, negative charging) to apply a uniform potential to the photoconductor drum 10. Other wire electrodes can be used as the discharge electrode 11a.

The exposure unit 12 as an image exposure means for each color is arranged such that the exposure position on the photosensitive drum 10 is between the discharge electrode 11a of the scorotron charger 11 and the development position of the developing device 13 and a developing sleeve 131. With respect to the photoconductor drum, the photoconductor drum is arranged on the upstream side in the rotation direction.

The exposure unit 12 is a linear exposure element 12a in which a plurality of LEDs (light emitting diodes) as image exposure light emitting elements arranged in the main scanning direction in parallel with the axis of the photosensitive drum 10 are arranged in an array. And a SELFOC lens 12b as an equal-magnification imaging element are configured as an exposure unit attached to a holder (not shown). The exposure unit 12 for each color is attached to the holding member 20. In addition to the exposure unit 12 for each color, the uniform exposure unit 12c and the simultaneous transfer exposure unit 12d are attached to the holding member 20 to form the base of the photosensitive drum 10. Housed inside. Image data of each color read by a separate image reading device and stored in the memory is sequentially read from the memory and input to the exposure unit 12 for each color as an electric signal.

As the exposure element, an element in which a plurality of light-emitting elements such as FL (phosphor light emission), EL (electroluminescence), PL (plasma discharge), and LED (light-emitting diode) are arranged in an array is used. The emission wavelength of the light emitting element used in this embodiment is usually Y, M, C
In the range of 680 nm to 900 nm, which has a high toner transparency, is preferable, but a shorter wavelength may be used since the color toner does not have sufficient transparency because image exposure is performed from the back surface.

A developing unit 13 provided in accordance with the color sequence in which an image is formed and a rotating photosensitive drum is provided in accordance with the color sequence.
In the present embodiment, the developing units 13 for Y and M are on the left side of the photosensitive drum 10 with respect to the rotation direction of the photosensitive drum 10 indicated by the arrow in FIG. Are arranged on the right side of the photosensitive drum 10 and the Y and M developing devices 1
3 and a scorotron charger 11 for C and K above the developing casing 138 of the developing unit 13 for C and K, respectively.
Is arranged.

The developing device 13 as a developing means for each color is
One-component or two-component developers of yellow (Y), magenta (M), cyan (C), and black (K) are respectively contained, and a predetermined gap is maintained with respect to the peripheral surface of the photosensitive drum 10, Rotating in the same direction as the rotation direction of the photoconductor drum 10 at the developing position, for example, a thickness of 0.5 mm to 1 m
m, cylindrical developing sleeve 131 made of non-magnetic stainless steel or aluminum material having an outer diameter of 15 mm to 25 mm
It has.

The developing unit 13 is urged by an abutting roller (not shown) to a gap of a predetermined value from the photosensitive drum 10, for example, 100 μm.
.About.1000 .mu.m and kept in a non-contact state, and when developing by the developing device 13 for each color, the developing sleeve 131
A developing bias to which a DC voltage or an AC voltage AC is further applied is applied to the photoreceptor, jumping development is performed by a one-component or two-component developer housed in the developing device, and a negatively charged photoreceptor that grounds the transparent conductive layer. Non-contact reversal development is performed by applying a DC bias of the same polarity as the toner (negative polarity in the present embodiment) to the drum 10 to attach the toner to the exposed portion. At this time, the precision of the development interval needs to be about 20 μm or less in order to prevent image unevenness.

The developing unit 13 for each color applies a developing bias voltage to the electrostatic latent image on the photosensitive drum 10 formed by the charging by the scorotron charger 11 and the image exposure by the exposure unit 12. (In the present embodiment, the photosensitive drum is negatively charged,
Reversal development is carried out with a negative polarity toner).

An image read by an image pickup element of an image reading apparatus separate from the apparatus or an image edited by a computer as a document image is temporarily stored in a memory as image data for each color of Y, M, C and K. Are stored and stored in.

A gear 10 provided on the rear flange 10b of the photoconductor drum 10 is driven through a gear G1 for driving by starting a photoconductor drive motor (not shown) when image recording is started.
G is rotated to rotate the photosensitive drum 10 in the clockwise direction indicated by the arrow in FIG. 1, and at the same time, Y disposed below the developing casing 138 of the yellow (Y) developing device 13 to the left of the photosensitive drum 10. The application of a potential to the photosensitive drum 10 is started by the charging action of the scorotron charger 11 described above.

After the photosensitive drum 10 is applied with a potential, the first color signal, that is, Y
Exposure by an electric signal corresponding to the image data is started, and an electrostatic latent image corresponding to the Y image of the original image is formed on the photosensitive layer on the surface by rotating and scanning the drum.

The latent image is reversal-developed by the Y developing device 13 in a state where the developer on the developing sleeve is not in contact with the developer, and a yellow (Y) toner image is formed in accordance with the rotation of the photosensitive drum 10.

Next, the photosensitive drum 10 is placed on the yellow (Y) toner image, and further on the left side of the photosensitive drum 10 and above the yellow (Y), a magenta (M) developing device 1.
A potential is applied by the charging action of the magenta (M) scorotron charger 11 arranged below the developing casing 138 of No. 3, and an electric signal corresponding to the second color signal of the M exposure unit 12, that is, the image data of M. Exposure is performed, and non-contact reversal development by the developing unit 13 for M forms a magenta (M) toner image on the yellow (Y) toner image in sequence.

By the same process, the developing casing 13 of the developing unit 13 for cyan (C) is located on the right side of the photosensitive drum 10.
8, a cyan (C) scorotron charger 11, an exposure unit 12 of C and a developing device 13 of C further provide a cyan (C) toner image corresponding to the third color signal, and also a photoconductor. The fourth color is provided by the black (K) scorotron charger 11, the exposure unit 12, and the developing device 13, which are arranged on the right side of the drum 10 and below the C and above the developing casing 138 of the black (K) developing device 13. A black (K) toner image corresponding to the signal is sequentially superimposed and formed, and a color toner image is formed on the peripheral surface of the photosensitive drum 10 within one rotation (toner image forming means).

Exposure unit 1 for Y, M, C and K
Exposure of the organic photosensitive layer of the photosensitive drum 10 by 2 is performed from the inside of the drum through the transparent substrate described above. Therefore, the exposure 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. It is possible to form an electrostatic latent image.

By the above-described image forming process, a superimposed color toner image serving as a back image is formed on the photosensitive drum 10 (first image carrying means) as an image carrier. The transfer roller 14c to which a DC voltage having the opposite polarity (positive polarity in the present embodiment) is applied to the superposed color toner image in the transfer area 14b by the driving roller 14d and the driven roller 1
4e, and is collectively transferred onto a toner image receiving member 14a (second image carrying means) provided in proximity to or in contact with the photosensitive drum 10. At this time, for example, uniform exposure is performed by the simultaneous transfer exposure device 12d using a light emitting diode so that good transfer is performed.

The toner remaining on the peripheral surface of the photoconductive drum 10 after the transfer is subjected to static elimination by the image carrier AC static eliminator 16 and then enters the cleaning device 19 or the photoconductive drum 10.
Cleaning blade 19a made of a rubber material abutting against
In order to eliminate the history of the photoreceptor up to the previous print, the peripheral surface of the photoreceptor is removed by, for example, exposure by a uniform exposure unit 12c before charging using a light emitting diode, and the charge at the previous print is removed. Is removed and the next color image formation of the front surface image is performed.

The back side image formed on the toner image receiving body 14a is synchronized with the transfer area 14b, and the surface image of the superimposed color toner image is transferred to the photosensitive drum in the same manner as in the above-described color image forming process. 10 is formed. It is necessary to change the image data so that the front side image formed at this time is a mirror image of the back side image formation on the image carrier.

The transfer sheet P, which is the transfer material, is sent out from the sheet feeding cassette 15 which is the transfer material storage means by the sending roller 15a and is conveyed to the timing roller 15b.

The recording paper P has a color toner image of the front surface image carried on the photosensitive drum 10 and a color toner image of the back surface image carried on the toner image receiving body 14a driven by the timing roller 15b. The paper is fed to the transfer area 14b in synchronism. At this time, the recording paper P is charged to the same polarity as the toner by the paper charger 14f as the transfer material charging means, adsorbed to the toner image receiving body 14a, and fed to the transfer area 14b. By charging the paper with the same polarity as that of the toner, it is possible to prevent the toner image on the toner image receiving body and the toner image on the image carrier from being attracted to each other, thereby preventing the toner image from being disturbed. Further, as the transfer material charging unit, a conductive roller, a brush charger, or the like, which can be brought into contact with and released from the toner image receiver, can be used.

A surface image on the peripheral surface of the photosensitive drum 10 is collectively recorded on a recording paper by a transfer unit 14c as a first transfer unit to which a voltage having a polarity opposite to that of the toner (positive polarity in this embodiment) is applied. It is transferred to the upper surface side (front side) of P. At this time, the back surface image on the peripheral surface of the toner image receiver 14a is not transferred to the recording paper P but exists on the toner image receiver 14a. Next, a backside image on the peripheral surface of the toner image receiving body 14a is collectively recorded 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 the present embodiment) is applied. The image is transferred to the lower surface (back surface) of the paper P. At the time of transfer by the transfer device 14c, uniform exposure is performed by a simultaneous transfer exposure device 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 device 14c. Is performed.

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

Repeated reversal development on the image carrier, the color toner images of the same polarity formed by superposition are collectively transferred to the toner image receiving body 14a without changing the polarity, and then the recording paper without changing the polarity. The batch transfer to P is preferable because it contributes to the improvement of transferability in the back side image formation. Also for the surface image formation, reversal development is repeatedly performed on the image carrier, and the color toner images of the same polarity formed by superimposition are collectively transferred to the recording paper P without changing the polarity. It is preferable because it contributes to improvement of the property.

As described 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 toner image receiver 14a has a thickness of 0.5 mm.
A 2.0 mm endless rubber belt, a semiconductive substrate of silicon rubber or urethane rubber having a resistance of 10 ⁸ Ω · cm to 10 ¹² Ω · cm, and a toner filming prevention layer outside the rubber substrate. It has a two-layer structure in which a fluorine coating having a thickness of 5 μm to 50 μm is performed. This layer also preferably has a similar semiconductivity. Instead of the rubber belt substrate, semiconductive polyester, polystyrene, polyethylene, polyethylene terephthalate, or the like having a thickness of 0.1 mm to 0.5 mm can also be used.

The recording paper P on which the color toner images are formed on both sides is discharged by a paper separation AC discharger 14h for separating the transfer material, separated from the toner image receiver 14a, and a heater is provided inside both rollers. The sheet is conveyed to a fixing device 17 as a fixing unit including two rollers.
By applying heat and pressure between the fixing roller 17a and the pressure roller 17b, the toner adhered to the front and back of the recording paper P is fixed, and the recording paper P on which double-sided image recording has been performed is sent by the paper discharge roller 18. And discharged to a tray outside the apparatus.

The toner remaining on the peripheral surface of the toner image receiver 14a after the transfer contacts and contacts the toner image receiver 14a provided in a toner image receiver cleaning device 14i as cleaning means for the toner image receiver. It is cleaned by a blade that can be released.

After the transfer, the toner remaining on the peripheral surface of the photosensitive drum 10 is subjected to static elimination by the image carrier AC static eliminator 16 and then moved to the cleaning device 19 or the rubber contacting the photosensitive drum 10. The material is scraped off into the cleaning device 19 by a cleaning blade 19a made of a material, and is collected by a screw 19b in a waste toner container (not shown). The photoconductor 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.

By using the above method, the superimposed color toner images are transferred in a batch, so that color deviation of the color image on the toner image receiver, toner scattering and rubbing hardly occur, and image deterioration is small. Double-sided color image formation is performed.

In the above image forming apparatus, it is needless to say that only one side is copied by the first image carrying means or the second image carrying means.

Next, description will be made with reference to FIGS. 1 and 4. The recording paper P of the image forming apparatus is provided on the upper side or the side of the fixing device 17.
An exhaust fan F1 serving as an air flow exhausting unit is provided on the exhaust side of the sheet, and the air inside the image forming apparatus is exhausted by the rotation of the exhaust fan F1 of the housing 101 provided on the side of the recording sheet P on the side of the image forming apparatus. The air is exhausted through the holes 101a and 101b. As the exhaust fan F1, for example, a sirocco fan provided in parallel with the fixing device 17 is used.
It is preferable that a uniform air flow is formed over the entire area in the longitudinal direction, but it is also possible to use a propeller fan, and when using a propeller fan, it is preferable to dispose a plurality of them in parallel with the fixing device 17.

By the rotation of the exhaust fan F1, through the ducts formed by the ventilation guide plates 201, 202, 203 and the ventilation guide plates 204, 205 at both longitudinal ends of the fixing device 17, the casing 101 at the bottom of the image forming apparatus main body is provided.
An air flow that flows upward through the air intake hole 101d provided in the fixing device 17 and the toner image receiving body 14a is formed, and inflow of outside air and discharge of air inside the machine are performed.

The heat of the toner image receiving body 14a from the fixing device 17 is blocked by the air flow, so that the toner image receiving body 14a is prevented from being heated by the heat of the fixing device 17, and the toner image receiving body 14a is prevented. Deterioration, deterioration, toner fusion and the like are reduced.

Further, the air intake hole 1 at the bottom of the image forming apparatus main body
While cooling the toner image receiving body 14a through 01e and 101f, an air flow that flows upward is formed across the space between the fixing device 17 and the toner image receiving body 14a, and inflow of outside air and discharge of air inside the apparatus to the outside of the apparatus. And do.

When the recording paper P is conveyed, the above-described air flow is separated from the toner image receiving body 14a and formed toward the upper side of the lower surface of the recording paper P conveyed to the fixing device 17 in the direction of the back surface image. Therefore, the leading end of the recording paper P is prevented from falling, and the recording paper P is floated up so that the recording paper P is satisfactorily conveyed.

Also, through the duct, the back surface transfer device 14g
Air near the corona discharger such as the paper separation AC static eliminator 14h and the paper separation AC static eliminator 14h is caused to flow along the toner image receptor 14a and the back surface transfer device 14g and the paper separation AC static eliminator 14h provided above the exhaust port 101a, An air flow to be discharged to the outside of the machine is formed through 101b, and outside air is introduced and air inside the machine is discharged to the outside of the machine. The air inside the machine is exhausted to the outside of the machine through the ozone filter FL1 provided in the exhaust fan F1. Ozone generated from the corona discharger such as the back surface transfer device 14g and the paper separation AC static eliminator 14h is decomposed by the ozone filter FL1 and the air inside the device is discharged.

Further, the air containing ozone generated by the scorotron charger 11 provided on the outer periphery of the photosensitive drum 10 is formed into the air flow flowing into the exhaust fan F1, and the ozone generated by the scorotron charger 11 is removed. It is decomposed by the ozone filter FL1 and discharged to the outside of the machine.

Regarding the second example of the method of forming the air flow and the method of conveying the transfer material from the second image carrier to the fixing device,
This will be described with reference to FIGS. FIG. 5 is a side view of essential parts showing a second example of the air flow formation and an example of the transport section.
FIG. 8 is a main part top view showing a second example of air flow formation and an example of a transfer part, FIG. 7 is a perspective view of a spur provided in the transfer part, and FIG. 8 is another example of a spur. FIG.

A color image is formed in the same manner as described in the color image forming process, but a conveying section 150 is provided between the toner image receiving body 14a and the fixing device 17 as fixing means, and the transfer material is formed. The recording paper P is conveyed from the toner image receiver 14a to the fixing device 17.

The transport section 150 includes a box 151 and a box 151.
And a wire 153 stretched around the box 151. The square hole 15 is formed in the upper surface 151d of the box 151.
1a and grooves 151b and 151c are provided at both ends of the square hole 151a, and a support shaft 152a is provided at the center of the spur 152. The support shaft 152a is dropped into the grooves 151b and 151c at both ends of the square hole 151a, and the spur 152 is rotatably attached to the box body 151.

As shown in FIGS. 5 and 6, the wire 153
Is stretched over the box 151 using the pin 154. At this time, the wire 153 as a guide member is stretched above the support shaft 152a at the center of rotation of the spur 152 by the convex portions 151e and 151f of the box 151. .

As shown in FIG. 7, the spur 152 serving as a spur-shaped rotating member preferably has a thickness of 0.05 mm to 0.5 mm.
mm, an outer diameter of 5 mm to 25 mm, for example, a hexagonal plate having an outer diameter of 10 mm, which is formed by etching a metal plate such as a stainless plate or a copper plate having a thickness of 0.2 mm and provided with a protruding portion 152b having a sharp tip. It consists of a member. This metal plate is grounded via a resistor of 10 ¹⁰ Ω to ^{10 14} Ω.

Further, as shown in FIG. 8, for example, a support shaft 252a is provided on a hexagonal spur 252 having an abacus bead-shaped section having an outer diameter of 5 mm to 25 mm and made of a resin material and provided with a sharp projection 252b. Those provided with can also be used. Further, the shape of the spur protrusion is not limited to a hexagon, and a shape having a plurality of protrusions such as pentagon, octagon, and decagon is used. This resin is 10 ¹⁰ Ω · cm
It is preferably grounded using a resistance member of 10 to ^{13 13} Ω · cm. The spur 152 is grounded via a high resistance member or by using a high resistance member because the toner and the transfer material are charged, and the charge accumulation of the spur 152 and the toner adhesion due to the mirror image force are eliminated to remove the toner image. This is to prevent the disturbance of.

The recording paper P on which the toner image is transferred is conveyed by the conveying section 1.
50, the support shaft 15 at the center of rotation of the spur 152
The recording paper P is formed by the wire 153 stretched above
Of the toner is scooped up and the toner image is not rubbed.
2, the spur 152 is driven to rotate while the tip 152 b of the spur 152 contacts or pierces the recording paper P, and the recording paper P is conveyed to the fixing device 17. In addition, spur 15
The trailing edge of the recording paper P is prevented from falling by the wire 153 as a guide member stretched above the support shaft 152a at the center of rotation of 2, and the toner image is conveyed without being rubbed.

The toner image receiving body 1 is provided close to the fixing device 17.
4a, and the conveyance unit 150 is arranged between the fixing device 17 and the toner image receiving body 14a.

An exhaust fan F2 as an air flow exhausting means is provided at one side end of the fixing device 17 in the longitudinal direction, and rotation of the exhaust fan F2 allows the ventilation guide plates 206 and 207 to move above and below the conveying section 150 as ventilation guides. The exhaust hole 1 is traversed horizontally across the transport unit 150 in parallel with the longitudinal direction of the fixing device 17.
The air flow to be discharged to 01c is formed, and the outside air is introduced and the air inside the machine is discharged outside the machine in a direction orthogonal to the discharge direction of the recording paper P. As the exhaust fan F2, for example, a sirocco fan or a propeller fan can be used as described above.

Exhaust fan F2 in the longitudinal direction of the fixing device 17
The air intake hole 1 is provided on one side of the housing 101 on the side opposite to the side where the
01g, 101h, 101i are provided to form the air flow.

The exhaust fan F2 is preferably arranged so that the center of rotation of the propeller of the exhaust fan F2 is above the passage surface of the recording paper P. Further, the ventilation partition plate 211 is provided with the fixing device 17 and the toner image receiver 14a. At a side end of the conveyance unit 150 provided between the recording paper P and the ventilation surface of the recording paper P, which is substantially horizontal.
Preferably, it is provided slightly below the ventilation surface of the recording paper P, and when the recording paper P as a transfer material passes, the flow velocity of the air flow on the upper surface side of the recording paper P is made higher than the flow velocity on the lower surface side thereof to float the recording paper P. Try.

The heat of the toner image receiving body 14a from the fixing device 17 is cut off by the heat of the fixing device 17 flowing into the toner image receiving body 14a by the above air flow.
a is prevented from being heated, the toner image receiving body 14a is deteriorated,
Deterioration, toner fusion and the like are reduced.

Further, the air around the corona discharger such as the back surface transfer device 14g and the paper separation AC static eliminator 14h is passed through the ventilation guide plate 207, and the toner image receiving body 14a and the back surface transfer device 14g provided above the toner image receiving body 14a. The air flows along the sheet separation AC static eliminator 14h to form an air flow to be discharged to the outside of the machine through the exhaust hole 101c, and is exhausted to the outside of the machine through the ozone filter FL2 provided in the exhaust fan F2. Back transfer device 14g
Ozone generated from a corona discharger such as a paper separation AC static eliminator 14h or the like is decomposed by the ozone filter FL2, and the air inside the machine is discharged.

In the above example, it is also possible to dispose the fixing device 17 and the toner image receiving body 14a close to each other without providing the conveying section 150, and the toner image is supplied from the fixing device 17 by the air flow of the exhaust fan F2. The heat of the image receiving body 14a is blocked and the toner image receiving body 14a is cooled.

Although the present invention has been described using the color image forming apparatus, it is needless to say that the present invention can be applied to a monochrome image forming apparatus. Further, the present invention includes not only the present method but also a modified example of forming a double-sided image.
Japanese Patent Application Laid-Open Nos. 63-180969 and 63-2, in which after inverting the polarity of the toner corresponding to the backside image shown in JP-A-28740, the toner is simultaneously transferred to both sides of the transfer material.
In the tandem method of JP-A-98255 and JP-A-1-44457, changing the process conditions and image data processing conditions between the front surface and the back surface as described above is used, and the image density and color tone are adjusted. And a double-sided image can be formed.

[0066]

According to the first aspect of the present invention, the heat from the fixing device is cut off by the inflow of the outside air and the discharge of the air inside the device to the outside of the device. The heating of the carrying means is prevented, deterioration, deterioration, and toner fusion of the second image carrying means are reduced, and good double-sided images are maintained for a long period of time.

According to the second aspect, the transfer material conveyed to the fixing device by the second image carrier is prevented from falling.

According to the third aspect of the present invention, deterioration and alteration of the second image bearing means due to ozone from the corona discharger of the separation section are prevented, and a good double-sided image is maintained for a long period of time.

According to the fourth aspect, the heat flowing into the fixing device is blocked by the inflow of the outside air and the discharge of the air inside the device to the outside of the device, so that the second image bearing means is generated by the heat from the fixing device. Is prevented, deterioration, deterioration, and toner fusion of the second image carrier are reduced, and a good double-sided image is maintained for a long period of time.

According to the fifth aspect, the transfer material is conveyed by the spur-shaped rotating member in a floating state, and the rubbing of the backside toner image is prevented.

According to the sixth aspect of the present invention, deterioration and alteration of the second image bearing means due to ozone from the corona discharger of the separation section are prevented, and a good double-sided image is maintained for a long period of time.

[Brief description of drawings]

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

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

FIG. 3 is a diagram illustrating a state where toner images are formed on both surfaces.

FIG. 4 is a main part top view showing a first example of air flow formation.

FIG. 5 is a side view of a main portion showing a second example of air flow formation and an example of a transport unit.

FIG. 6 is a top view of relevant parts showing a second example of air flow formation and an example of a transport unit.

FIG. 7 is a perspective view of a spur provided in the transport section.

FIG. 8 is a diagram showing another example of a spur.

[Explanation of symbols]

10 Photoreceptor Drum 11 Scorotron Charger 12 Exposure Unit 13 Developing Device 14a Toner Image Receptor 14c Transfer Device 14g Back Transfer Device 14h Paper Separation AC Charger 17 Fixing Device 101 Housing 101a, 101b, 101c Exhaust Hole 101d, 101e, 101f, 101g, 101h,
101i Intake hole 150 Conveying section 152 Spur 201, 202, 203, 204, 205, 206 Ventilation guide plate 211 Ventilation partition plate F1, F2 Exhaust fan FL1, FL2 Ozone filter P Recording paper

Claims (6)

[Claims] 1. A first image bearing means for bearing a toner image formed by a toner image forming means, and a toner image carried on the first image bearing means are collectively transferred and transferred. Second image carrying means for carrying the toner image on the surface again, first transfer means for transferring the toner image carried by the first image carrying means onto the surface of the transfer material, and the second image Second transfer means for transferring the toner image carried by the carrying means to the back surface of the transfer material, and the toner image carried by the first image carrying means by the first transfer means for the transfer material. Of the toner image carried on the front surface of the transfer material, and the toner image carried on the second image carrying means by the second transfer means on the back surface of the transfer material, and the toner image transferred on both surfaces of the transfer material. An image forming apparatus having a fixing device for fixing The second image bearing means is disposed in the vicinity of the fixing device, and the outside air flowing into the image forming apparatus main body is passed between the fixing device and the second image bearing means to allow the fixing device to operate. An image forming apparatus comprising: a discharging unit configured to discharge the transfer material to the outside of the image forming apparatus. 2. The image forming apparatus according to claim 1, wherein the outside air is introduced from a rear surface direction of the transfer material. 3. The image forming apparatus according to claim 1, wherein the outside air is introduced along a separation portion of the transfer material which is arranged close to the second image carrier. 4. A first image bearing means for bearing a toner image formed by a toner image forming means, and a toner image carried on the first image bearing means are collectively transferred and transferred. Second image carrying means for carrying the toner image on the surface again, first transfer means for transferring the toner image carried by the first image carrying means onto the surface of the transfer material, and the second image Second transfer means for transferring the toner image carried by the carrying means to the back surface of the transfer material, and the toner image carried by the first image carrying means by the first transfer means for the transfer material. Of the toner image carried on the front surface of the transfer material, and the toner image carried on the second image carrying means by the second transfer means on the back surface of the transfer material, and the toner image transferred on both surfaces of the transfer material. An image forming apparatus having a fixing unit for fixing Discharge that allows the outside air that has flowed into the main body of the image forming apparatus to pass through between the fixing device and the second image carrying unit and is discharged to the outside of the image forming apparatus in a direction orthogonal to the discharge direction of the transfer material. An image forming apparatus comprising means. 5. A spur-shaped rotating member that conveys the transfer material is provided between the fixing device and the second image carrier.
The image forming apparatus according to claim 4, wherein outside air is introduced into the upper and lower portions of the transfer material. 6. The image forming apparatus according to claim 4, wherein the outside air is introduced along a separation portion of the transfer material which is arranged close to the second image carrier.