JPH09258493A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently record the vertically fed images of front and rear surface on the front and rear surfaces of transfer material in a double-sided image forming device simultaneously performing fixing by providing toner images on the front and rear surfers of the transfer material. SOLUTION: An original E is carried on a platen glass 51 passing a paper feeding route constituted of carrying drums 54A, 54B and 54C, while the images of the rear surface is read in a state where a first mirror unit 57 and a second mirror unit 58 are moved from the initial position of scanning shown by broken lines to a stopping position shown by solid lines. Next, respective mirror units are returned to the initial position of scanning and a front surface image on the platen glass 51 is read from the top end side of the original D same as a rear surface image, and the picture signal of the rear surface image is electrically reversed in a main scanning direction, so that it is outputted to a device main body from a reverse direction. The rear surface image is formed at a first image carrying means at the device main body, and is transferred to a second image carrying means, and next the front surface image is formed on the first carrying means, and is fixed after transferring it on the front and rear surfaces of the transfer material by first and second transferring means.

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.
JP, JP-A-1-44457, JP-A-4-21
Japanese Patent No. 4576 proposes a method in which the transfer material is fixed on both sides after being formed on both sides.

[0004]

However, as is well known, an image forming apparatus for forming a double-sided image by using the above-mentioned double-sided reversal sheet feeding apparatus requires a long processing time for copying because the transfer material conveying distance becomes long. In addition, since the transfer material is heated twice for fixing the image, there is a problem that the paper quality is damaged.

Therefore, the present inventor previously provided two image carrying means and two transfer means to transfer the toner images to both surfaces of the transfer material and simultaneously fix the transfer material having the toner images on both surfaces. We have conducted research on a device that can perform double-sided copying and realized an image forming device that can significantly increase the processing speed.

The present invention is further problematic in the above-mentioned image forming apparatus in that the front and back images are recorded in opposite directions depending on the feeding direction of the original, and the back image is re-transferred so that the image is mirror-reversed. It is an object of the present invention to provide an image forming apparatus that forms an image similar to a document regardless of whether the front and back images formed on the transfer material are vertical documents or horizontal documents.

[0007]

The above object is to carry a toner image formed on the surface by a toner image forming means.
Image carrying means, the second image carrying means for carrying the toner images carried on the first image carrying means collectively on the surface, and carrying the transferred toner images on the surface, and the first image carrying means. First transfer means for transferring the toner image carried by the image carrying means onto one surface of the transfer material, and the toner image carried by the second image carrying means on the other surface of the transfer material. An image forming apparatus having a second transfer unit for transferring and a fixing unit for fixing the toner images transferred on both sides of the transfer material, wherein a double-sided image is formed on the transfer material in a vertical feed. ,
An image forming apparatus (invention according to claim 1) characterized by having a reversing means for reversing the image data in the main scanning direction with respect to the front side image formation at the time of the back side image formation, and the front side by the toner image forming means. A first image carrying unit carrying the formed toner image and a toner image carried on the first image carrying unit are collectively transferred, and a second image carrying unit carries the transferred toner image on the surface. Image carrying means, first transfer means for transferring the toner image carried on the first image carrying means to one surface of the transfer material, and toner carried on the second image carrying means. What is claimed is: 1. An image forming apparatus comprising: a second transfer unit that transfers an image to the other surface of the transfer material; and a fixing unit that fixes the toner images transferred to both surfaces of the transfer material. If a double-sided image is formed on the Sometimes, an image forming apparatus characterized by having an inverting means for inverting the image data in the sub-scanning direction with respect to the surface image formation (the invention according to claim 2),
And a first image bearing means for bearing the toner image formed on the surface by the toner image forming means, and the toner image carried on the first image bearing means are collectively transferred, and the transferred toner Second image carrying means for carrying an image on the surface; first transfer means for transferring the toner image carried by the first image carrying means onto one surface of a transfer material; and the second image An image forming apparatus having second transfer means for transferring the toner image carried by the carrying means to the other surface of the transfer material, and fixing means for fixing the toner images transferred on both surfaces of the transfer material. Therefore, there is a discriminating means for discriminating whether the original image to be printed is vertically fed or horizontally fed, and in accordance with the discrimination result by the discriminating means, the image data is transferred to the front side image in the main scanning direction or the sub-image when the back side image is formed. Having a reversing means for reversing in the scanning direction It is achieved taken by the image forming apparatus, comprising (invention according to claim 3).

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Prior to the description of the present invention, three embodiments of an image forming apparatus to which the present invention is applied will be described. The present invention is not limited to the embodiments described below. The description in this section 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 transferring a color toner image to a transfer material, an image to be transferred to a surface of the transfer material on the side facing the image carrier in the transfer area is a surface image or the other of the transfer material. The image transferred to the surface on the side of is referred to as a back surface image. Each of the embodiments described below is an example of a color image forming apparatus that forms a color image, but the present invention is also applied to a monochrome image forming apparatus.

The image forming process and each mechanism of the first embodiment of the color image forming apparatus of the present invention will be described with reference to FIGS. FIG. 1 is a sectional configuration diagram of a first embodiment of a color image forming apparatus of the present invention, FIG. 2 is a side sectional view of the image carrier of FIG. 1, and FIG. 3 is a first embodiment. FIG. 3 is a diagram showing a toner image formation state on both sides relating to the above.

The photosensitive drum 10, which is an image bearing member, is provided with a cylindrical substrate formed of a transparent member such as glass or transparent acrylic resin inside, and a transparent conductive layer a-
A photosensitive layer such as a Si layer or an organic photosensitive layer (OPC) is formed on the outer periphery of the substrate.

The photosensitive drum 10 is sandwiched by a front flange 10a and a rear flange 10b, and the front flange 10a is supported by bearings by guide pins 10P1 provided on a cover 103 attached to a front side plate 101 of the apparatus main body.
The rear flange 10b is fitted onto a plurality of guide rollers 10R attached to the rear side plate 102 of the main body of the apparatus to hold the photosensitive drum 10. A gear 10G provided on the outer periphery of the rear flange 10b is meshed with a driving gear G1, and the power of the gear 10G rotates the photosensitive drum 10 in a clockwise direction indicated by an arrow in FIG. 1 with the transparent conductive layer being grounded. It

In the present embodiment, it is sufficient that the photoconductive layer of the photosensitive drum has an exposure light amount capable of giving an appropriate contrast. Therefore, the light transmittance of the transparent substrate of the photosensitive drum in the present embodiment does not need to be 100%, and may have a characteristic that some light is absorbed when the exposure beam is transmitted. As the material of the translucent substrate, an acrylic resin, particularly one polymerized using methyl methacrylate monomer, has transparency, strength, accuracy,
Acrylic, fluorine used for other general optical members, etc.
Various translucent resins such as polyester, polycarbonate, and polyethylene terephthalate can be used. Further, as long as it has a light-transmitting property with respect to the exposure light, it may be colored. The light-transmitting conductive layer is made of indium-tin-oxide (ITO), tin oxide, lead oxide, indium oxide, copper iodide, or a light-transparent metal thin film made of Au, Ag, Ni, Al, or the like. As a film forming method, a vacuum evaporation method, an active reaction evaporation method, various sputtering methods, various CVD methods, a dip coating method, a spray coating method, and the like are used. As the photoconductor layer, an amorphous silicon (a-Si) alloy photosensitive layer, an amorphous selenium alloy photosensitive layer, or various organic photosensitive layers (OPC) can be used.

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 exposing 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 developing 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). Exposure for each color is performed on a cylindrical holding member 20 fixed with guide pins 10P2 provided on the rear plate 102 of the apparatus main body and guide pins 10P1 provided on the cover 103 attached to the front plate 101 as guides. Unit 12, uniform exposure device 1
2c and a transfer simultaneous exposure device 12d are attached and housed inside the substrate of the photoconductor drum 10. It is read by an image reading device provided separately or on the upper surface of the device, which will be described later.
The image data of each color 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, there is a linear element in which a plurality of light emitting elements such as FL (fluorescent substance emission), EL (electroluminescence), PL (plasma discharge), LED (light emitting diode) are arranged in an array. Used. The emission wavelength of the light emitting element used in this embodiment is usually Y,
M and C toners having a high transparency in the range of 680 to 900 nm are preferable, but since the image exposure is performed from the back surface, even at the above wavelengths or shorter wavelengths that do not have sufficient transparency for color toners. Good.

In the present embodiment, the developing device provided in accordance with the color order in which images are formed and the rotating photosensitive drum is arranged in the rotational direction of the photosensitive drum 10 in the present embodiment. On the other hand, the Y and M developing devices 13 are arranged on the left side of the photoconductor drum 10, and the C and K developing devices 13 are arranged on the right side of the photoconductor drum 10. The Y and M scorotron chargers 11 are arranged below, and the C and K scorotron chargers 11 are arranged above the developing casing 138 of the C and K developing units 13.

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

The developing device 13 is provided with an abutting roller (not shown) and 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 photosensitive drum, a jumping development is performed with a one-component or two-component developer contained in the developing device, and a negatively charged photosensitive member grounds the transparent conductive layer. The same polarity as the toner for the drum 10 (minus polarity in this embodiment)
Is applied, and non-contact reversal development is performed in which toner is adhered to an exposed portion.

The developing device 13 for each color applies a developing bias voltage to the electrostatic latent image formed on the photoconductor drum 10 formed by the charging by the scorotron charger 11 and the image exposure by the exposure unit 12 described above. The toner having the same polarity as the charging polarity in a non-contact state by the non-contact developing method according to (the photosensitive drum in this embodiment is negatively charged,
Reversal development is carried out with a negative polarity toner).

A gear 10 provided on the rear flange 10b of the photoconductor drum 10 is driven through a drive gear G1 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 a potential is applied to the photosensitive drum 10, exposure is started by a first color signal, that is, an electric signal corresponding to the Y image data in the Y exposure unit 12, and the surface of the photosensitive drum 10 is exposed by rotational scanning of the drum. An electrostatic latent image corresponding to the Y image of the original image is formed on the layer.

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 magenta (M) developing unit 1 on the yellow (Y) toner image and further on the left of the photosensitive drum 10 and above the yellow (Y).
3 is provided with a potential by the charging action of the magenta (M) scorotron charger 11 disposed below the developing casing 138, 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 by non-contact reversal development by the developing device 13 of M, and magenta (M) is formed on the yellow (Y) toner image.
Toner images are sequentially superposed and formed.

By the same process, the developing casing 13 of the cyan (C) developing device 13 is provided 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 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. In order to stabilize the temperature inside the photosensitive drum 10 and prevent the temperature from rising due to the heat generated by each exposure optical system 12, a material having good thermal conductivity is used for the holding member 20, and a heater 201 is used when the temperature is low. When the temperature is high, it can be suppressed to a level without any trouble by taking measures such as radiating heat to the outside through the heat pipe 202.

By the above image forming process, a superposed color toner image to be a back side image is formed on the photosensitive drum 10 (first image carrying means) as an image bearing member, and the back side image on the photosensitive drum 10 is formed. In the transfer area 14b, the superimposed color toner image is stretched between the driving roller 14d and the driven roller 14e by the transfer device 14c to which a voltage having a polarity opposite to that of the toner (positive polarity in this embodiment) is applied. Toner image receiving body 14a (second image carrying means) provided close to or in contact with the drum 10.
It is transcribed all at once. 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 photosensitive 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 photosensitive 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 and the transfer area 14b are synchronized with each other, and the front side image of the superimposed color toner image is formed on the photosensitive drum in the same manner as in the above-mentioned color image forming process. Formed on 10.

Recording paper P, which is a transfer material, is sent out by a feed roller 15a from a paper feed cassette 15 which is a transfer material storage means, fed by a feed roller 15b, and conveyed to a timing roller 15c.

The recording paper P is driven by the timing roller 15c to form a color toner image of a front surface image carried on the photosensitive drum 10 and a color toner image of a rear surface image carried on the toner image receiver 14a. Are fed to the transfer area 14b in synchronization with the above. At this time, the recording paper P is charged to the same polarity as the toner by the paper charger 14f, 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.

The surface image on the peripheral surface of the photosensitive drum 10 is collectively recorded on the recording paper P by the transfer device 14c to which a voltage of the opposite polarity (plus polarity in this embodiment) to the toner is applied.
(First transfer means). 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,
Polarity opposite to toner (positive polarity in this embodiment)
The transfer of the back surface image on the peripheral surface of the toner image receiving body 14a to the lower surface side of the recording paper P is collectively performed by the back surface transfer device 14g to which the above voltage is applied (second transfer means). At the time of transfer by the transfer device 14c, the transfer device 14c
Uniform exposure is performed by a transfer simultaneous exposure device 12d, which is provided inside the photosensitive drum 10 so as to face the above, and uses, for example, a light emitting diode.

Since the toner images of the respective colors are overlapped with each other, it is preferable that the upper layer toner and the lower layer toner are charged with the same charge amount and the same polarity 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.

The reversal development is repeated on the image carrier, and the color toner images of the same polarity formed by superimposition are collectively transferred to the toner image receiver 14a without changing the polarity, and then the recording paper is changed without changing the polarity. The batch transfer to P is preferable because it contributes to the improvement of the transferability of the backside 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 front and back surface image forming method. 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 0.5-2.
An endless rubber belt of 0 mm, a semiconductive substrate of silicon rubber or urethane rubber having a resistance value of 10 ⁸ to 10 ¹² Ω · cm, and a thickness of 5 μm to 50 μm as a toner filming prevention layer outside the rubber substrate. And a two-layer structure with fluorine coating. This layer also preferably has a similar semiconductivity. 0.1-thick instead of rubber belt base
0.5mm semiconductive polyester or polystyrene,
Polyethylene, polyethylene terephthalate and the like 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 is removed from the toner image receiver cleaning device 14i.
Cleaning. The toner remaining on the peripheral surface of the photosensitive drum 10 after the transfer is transferred to the image carrier AC static eliminator 1.
After being discharged by 6, the cleaning device 19 is scraped into the cleaning device 19 by the cleaning blade 19a made of a rubber material which is in contact with the photosensitive drum 10, and is collected by a screw 19b in a toner discharge container (not shown). To be done. 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 the above method, the superimposed color toner images are collectively transferred, so that color deviation of the color image on the toner image receiver, toner scatter and rubbing hardly occur, and good double-sided color with little image deterioration. An image is formed.

Next, the image forming process and each mechanism of the second embodiment of the color image forming apparatus of the present invention will be described with reference to FIGS. 4 and 5. FIG. 4 is a cross-sectional configuration diagram of a second embodiment of the color image forming apparatus of the present invention, and FIG. 5 is a diagram showing a toner image forming state on both surfaces according to the second embodiment. Members having the same functions and structures as those in the first embodiment are designated by the same reference numerals.

The toner image receiving body 14a stretched between the driving roller 14d and the driven roller 14e is the driving roller 14d.
4 is rotated in the direction indicated by the dotted arrow a in FIG. 4 and the following image formation is performed in a state of being separated from the photosensitive drum 10.

The photosensitive drum 10, which is an image carrier, has a cylindrical substrate provided inside and a photosensitive layer such as a conductive layer, an a-Si layer or an organic photosensitive layer (OPC) formed on the outer periphery of the substrate. Yes, it is rotated in the clockwise direction indicated by the arrow in FIG. 4 in the grounded state.

The photosensitive drum 10 as the image bearing member is driven and rotated, and in order to eliminate the history of the photosensitive drum 10 up to the pre-printing, the uniform exposure device 1 as the discharging means before charging.
21a, for example, a light-emitting diode is used to uniformly expose the peripheral surface of the photoconductor to remove the charge from the previous printing.

Scorotron charger 11 as charging means
Performs a charging action (in this embodiment, negative charging) on the above-described organic photoconductor layer of the photoconductor drum 10 by the control grid held at a predetermined potential and the corona discharge by the discharge electrode 11a. A uniform electric potential is applied to.

The photosensitive drum 10 is a scorotron charger 1.
An image that has been uniformly charged to the peripheral surface by the unit 1 and then electrically read by an exposure unit 121 as an image exposing unit by an image reading device provided separately or on the upper surface of the device and electrically processed. Image exposure is performed based on the signal, and a latent image is formed on the photosensitive drum 10.

An exposure unit 121 as an image exposing means is a semiconductor laser as a light emitting element (not shown), and a rotary polygon mirror 12 for rotationally scanning a laser beam emitted from the semiconductor laser.
1b, an fθ lens 121c, a reflection mirror 121d, and the like, and a laser beam emitted from a semiconductor laser (not shown) is rotationally scanned by the rotary polygon mirror 121b, and rotates via the fθ lens 121c, the reflection mirror 121d, and the like. Image exposure is performed based on an image signal in the main scanning direction of the drum 10, and a latent image is formed on the photoconductor drum 10.

The peripheral portion of the photosensitive drum 10 is a developing means in which a developer composed of toner such as yellow (Y), magenta (M), cyan (C), black (K) and a carrier is filled. The developing device 13 for each color is provided, and first, development of the first color (for example, yellow) is performed by the developing sleeve 131.

The developing device 13 uses a non-contact developing method by applying a developing bias voltage to the electrostatic latent image formed on the photosensitive drum 10 formed by the charging by the scorotron charger 11 and the image exposure by the exposure unit 121. In a non-contact state, development is performed by reversal development with toner having the same polarity as the charging polarity (in this embodiment, the photosensitive drum is negatively charged, toner having a negative polarity).

The developing device 13 is provided with an abutting roller (not shown) and the photosensitive drum 10 and a predetermined value, for example, 100 μm to 10
The developing sleeve 13 is maintained in a non-contact state with a gap of 00 μm, and during the developing operation by the developing device 13, a developing bias in which a direct current or an alternating current is applied to the developing sleeve 131 is applied, and the one-component or two-component developing accommodated in the developing device is applied. A jumper development with an agent is performed, and a DC bias having the same polarity (negative polarity in this embodiment) as that of the toner is applied to the negatively charged photosensitive drum 10 that grounds the transparent conductive layer to apply toner to the exposed portion. The non-contact reversal development is performed to attach the.

After the development of the first color is completed, the image process of the second color (for example, magenta) is started, and the photoconductor drum 10 is again processed.
Are uniformly charged by the scorotron charger 11, and a latent image based on the image data of the second color is formed by the exposure unit 121. At this time, the charge removal by the uniform exposure means 121a performed in the image forming process for the first color is not performed. Two
Development with the magenta developer of the color is the development sleeve 13
1 is performed. The development is performed by non-contact reversal development by applying an AC bias and a DC bias in a superimposed manner between the developing sleeve 131 and the photosensitive drum 10.

For the third color (cyan) and the fourth color (black), the same image forming process as for the second color is performed, and four color toner images are superposed and developed on the photosensitive drum 10 (toner image). Forming means).

By the above image forming process, a superposed color toner image to be a back side image is formed on the photosensitive drum 10 (first image carrying means) as an image carrying body.
The toner image receiving body 14a is rotated about the axis of the driving roller 14d in the direction shown by the dotted arrow b in FIG. 4, and is brought into contact with the photosensitive drum 10. At the fifth rotation of the photoconductor drum 10, the superimposed color toner image of the back side image on the photoconductor drum 10 is applied with a voltage having a polarity opposite to that of the toner (a positive polarity in this embodiment) in the transfer area 14b. The transfer device 14c collectively transfers the toner image on the toner image receiver 14a (second image carrier) provided in contact with the photosensitive drum 10.

After the superposed color toner images of the back side images on the photosensitive drum 10 are collectively transferred onto the toner image receiving body 14a, the toner image receiving body 14a is again centered on the axis of the driving roller 14d as shown in FIG. Is rotated in the direction indicated by the dotted arrow a, and is separated from the photoconductor drum 10.

The toner remaining on the peripheral surface of the photoconductor drum 10 after the transfer is subjected to static elimination by the image carrier AC static eliminator 16 and then goes to the cleaning device 19 or the photoconductor drum 10.
Cleaning blade 19a made of a rubber material abutting against
In order to eliminate the history of the photoconductor until the previous printing, the peripheral surface of the photoconductor is erased by the exposure by the uniform exposure device 121a before the charging using a light emitting diode, for example, and the charge at the time of the previous printing is performed. Are removed and color image formation of the next surface image is subsequently performed.

In the same manner as the color image forming process described above, the surface image of the superimposed color toner image is formed on the photosensitive drum 10.

Next, the front surface image formed on the photosensitive drum 10 and the back surface image formed on the toner image receiving body 14a are synchronized with each other in the transfer area 14b so that the toner image receiving body is formed. 14a is rotated about the axis of the drive roller 14d in the direction indicated by the dotted arrow b in FIG. 4, and is brought into contact with the photosensitive drum 10.

The recording paper P, which is a transfer material, is fed from the paper feed cassette 15 which is a transfer material storage means by the feed roller 15a, fed by the feed roller 15b and conveyed to the timing roller 15c.

The recording paper P is driven by the timing roller 15c, and the color toner image of the front surface image carried on the photosensitive drum 10 and the color toner image of the back surface image carried on the toner image receiving body 14a are recorded. Are synchronized and fed to the transfer area 14b. At this time, the recording paper P is charged to the same polarity as the toner by the paper charger 14f, 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.

The surface image on the peripheral surface of the photosensitive drum 10 is collectively recorded on the recording paper P by the transfer device 14c to which a voltage having a polarity opposite to that of the toner (positive polarity in this embodiment) is applied.
(First transfer means). 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,
Polarity opposite to toner (positive polarity in this embodiment)
The transfer of the back surface image on the peripheral surface of the toner image receiving body 14a to the lower surface side of the recording paper P is collectively performed by the back surface transfer device 14g to which the above voltage is applied (second transfer means).

Since the toner images of the respective colors are overlapped with each other, it is preferable that the upper layer toner and the lower layer toner are charged with the same charge amount and the same polarity 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.

From the above, in 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-mentioned front and back image forming methods, and then, A double-sided image forming method in which the second transfer unit is operated to form a color toner image on the back surface of the transfer material is preferably adopted.

The toner image receiver 14a has a thickness of 0.5-2.
An endless rubber belt of 0 mm, a semiconductive substrate of silicon rubber or urethane rubber having a resistance value of 10 ⁸ to 10 ¹² Ω · cm, and a thickness of 5 μm to 50 μm as a toner filming prevention layer outside the rubber substrate. And a two-layer structure with fluorine coating. This layer also preferably has a similar semiconductivity. 0.1-thick instead of rubber belt base
0.5mm semiconductive polyester or polystyrene,
Polyethylene, polyethylene terephthalate and the like can also be used.

The recording paper P on which the color toner images are formed on both sides is discharged by the paper separation AC discharger 14h for separating the transfer material, separated from the toner image receiving body 14a, and both rollers have heaters. The sheet is conveyed to a fixing device 17 as a fixing unit composed of 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 image receiver 14a is again driven by the drive roller 1.
It is rotated in the direction shown by the dotted arrow a in FIG. 4 about the axis of 4d and separated from the photosensitive drum 10. The toner remaining on the peripheral surface of the toner image receiving body 14a after the transfer is cleaned by the blade of the toner image receiving body cleaning device 14i which is brought into contact with the toner image receiving body 14a. Also,
The toner remaining on the peripheral surface of the photoconductor 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 a cleaning blade made of a rubber material contacting the photoconductor drum 10. 19a is scraped off into the cleaning device 19 and screw 19b
Is collected in an unillustrated waste toner container. The photoconductor drum 10 from which the residual toner has been removed by the cleaning device 19 is uniformly charged by the scorotron charger 11 and enters the next image forming cycle.

Since the superimposed color toner images are collectively transferred by the above-described method, color deviation of the color image on the toner image receiver, toner scattering and rubbing are less likely to occur, and good double-sided color with little image deterioration. An image is formed.

Further, the image forming process and each mechanism of the third embodiment of the color image forming apparatus of the present invention will be described with reference to FIG. FIG. 6 is a sectional configuration diagram of a third embodiment of the color image forming apparatus of the invention. In this embodiment, the color toner image on the image carrier is formed by the same image forming process as in the first embodiment, and the color toner image on the image carrier is transferred to the toner image receiver or the intermediate image transfer member via the intermediate transfer member. The toner image is transferred to the transfer material, and therefore the arrangement of the toner image receiving body and the feeding direction of the transfer material are opposite to those in the first embodiment. Members having the same functions and structures as those in the first embodiment are designated by the same reference numerals.

A transfer belt 41 as an intermediate transfer member is provided so as to face the photosensitive drum 10 as an image carrier,
A first roller 42 as a transfer roller for pressing the intermediate transfer belt 41 against the photosensitive drum 10, a second roller 43 for pressing the intermediate transfer belt 41 against the toner image receiving body 14a in the transfer area 14b, and a backup roller 44, Stretched between. Reference numeral 45 is an intermediate transfer belt cleaning device.

In the same manner as described in the first embodiment, the scorotron charger 1 as the charging means for each color.
1. An overlapping color toner image is formed on the peripheral surface of the photosensitive drum 10 within one rotation of the photosensitive drum 10 by the exposure unit 12 as the image exposing unit and the developing device 13 as the developing unit (toner image formation). means).

The toner image forming means forms a superposed color toner image as a back side image on the photoconductor drum 10 as an image carrier, and the superposed color toner image of the back side image on the photoconductor drum 10 is transferred to the transfer roller. After being temporarily transferred to the intermediate transfer belt 41 (first image carrier) by 42, in the transfer area 14b, a transfer device 14c to which a voltage having a polarity opposite to the toner (positive polarity in the present embodiment) is applied, Drive roller 14d and driven roller 14e
The image is collectively transferred onto the toner image receiving body 14a (second image carrying means) which is stretched between and provided close to or in contact with the photosensitive drum 10.

Again, the surface image of the superimposed color toner image is formed on the photosensitive drum 10 by the toner image forming means and transferred to the intermediate transfer belt 41.

A recording paper P as a transfer material is formed on the photosensitive drum 10, and once transferred to the intermediate transfer belt 41, the color toner image of the surface image carried on the intermediate transfer belt 41 and the toner image receiver. 14a is synchronized with the color toner image of the back side image carried on the transfer area 14a.
sent to b. At this time, the recording paper P is the paper charger 14f.
Is charged to the same polarity as the toner by the toner, and the toner image receiving body 1
It is adsorbed by 4a 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.

The surface image on the peripheral surface of the intermediate transfer belt 41 is collectively transferred onto the upper surface side of the recording paper P by the transfer device 14c to which a voltage having a polarity opposite to the toner (plus polarity in this embodiment) is applied. (First transfer means). On this occasion,
The rear surface image on the peripheral surface of the toner image receiving body 14a is not transferred to the recording paper P and exists on the toner image receiving body 14a. Next, the back surface image on the peripheral surface of the toner image receiving body 14a is collectively transferred to the lower surface side of the recording paper P by the back surface transfer device 14g to which a voltage having a polarity opposite to the toner (plus polarity in this embodiment) is applied. (Second transfer means).

The toner image receiver 14a has a thickness of 0.5-2.
An endless rubber belt of 0 mm, a semiconductive substrate of silicon rubber or urethane rubber having a resistance value of 10 ⁸ to 10 ¹² Ω · cm, and a thickness of 5 μm to 50 μm as a toner filming prevention layer outside the rubber substrate. And a two-layer structure with fluorine coating. This layer also preferably has a similar semiconductivity. 0.1-thick instead of rubber belt base
0.5mm semiconductive polyester or polystyrene,
Polyethylene, polyethylene terephthalate and the like can also be used. The intermediate transfer belt 41 can be made of the same material as the toner image receiving body 14a.

The recording paper P on which the color toner images are formed on both sides is neutralized by the paper separation AC neutralizer 14h for separating the transfer material and separated from the toner image receiving body 14a, and both rollers have heaters. The sheet is conveyed to a fixing device 17 as a fixing unit composed of two heating rollers,
By applying heat and pressure, the adhered toner on the front and back of the recording paper P is fixed, double-sided image recording is performed, and the toner is discharged to a tray outside the apparatus.

Toner image receiver 14 after transfer in the embodiment
The toner remaining on the peripheral surface of a is a toner image receiver cleaning device 14i capable of contacting and releasing the toner image receiver 14a.
The blade is cleaned.

Since the superimposed color toner images are transferred in a batch by the above method, color deviation of the color image on the toner image receiver, toner scattering and rubbing are less likely to occur, and good double-sided color with little image deterioration. An image is formed.

In the above first to third embodiments, it is needless to say that the first image forming means makes a copy on only one side.

The image data for each color of the document input to the color image forming apparatus according to the first to third embodiments is, for example, an image separate from the apparatus main body shown in each of FIGS. 7 and 8. It is read by the reading device 50.

The image reading device 50 includes a document feeding section 50A arranged above a transparent platen glass 51, and an imaging lens 59 and an image pickup device CC arranged below and fixed.
D, a movable first mirror unit 57 and a movable second mirror unit 58, and a scanning optical system 50B for reading an image of a document, which is a unit of the color image forming apparatus described above as a separate unit. It is installed on the top of the main body.

In the original feeding section 50A, the double-sided originals D are stacked on the original table 52 in the order of pages from the upper surface side, and are sequentially unloaded from the uppermost original D by the rotation of the unloading roller 52A, and the originals are fed through the transport rollers 53. D is the transport drum 54
On the peripheral surface of A, the back surface image faces the platen glass 51, and the back surface image of the document D moving at a constant speed here is read by the light receiving element CCD of the scanning optical system 50B at the fixed position.

Next, the document D is turned upside down by the transport drums 54B and 54C, and is temporarily stopped by the stop plate T with the surface image facing the platen glass 51 on the circumferential surface of the transport belt 55. The surface image at the stop position is read by the light receiving element CCD of the scanning optical system 50B by the first mirror unit 57 and the second mirror unit 58 which move and scan. When the reading of the surface image is completed, the stop plate T
The document D is conveyed again and is ejected to the tray 56 in the downward page order by the ejection roller 56A.

In the image forming apparatus of the present invention, when the image is formed on the transfer material in the longitudinal direction, when the back side image is formed on the transfer material, the image data is transferred in the main scanning direction with respect to the front side image. A means for reversing is provided. Further, when an image is formed on the transfer material in a lateral direction, a means for inverting the image data in the sub-scanning direction with respect to the front surface image is formed when the back surface image is formed on the transfer material. That is, in the image forming apparatus of the present invention, when the image is formed on the transfer material in the vertical or horizontal direction, when the rear surface image is formed on the transfer material, the front surface image is formed in a regular shape. A means for inverting the image data in the main scanning direction or the sub-scanning direction is provided, and when the front side image is formed on the transfer material, the image data is transferred to the main scanning direction or the back side image formed in a normal form. The same applies to a device provided with a means for reversing in the sub-scanning direction.

The present invention will be described below with reference to the first to third embodiments.

(Embodiment 1) An embodiment of the present invention according to claim 1 will be described with reference to FIGS.

When the original image is vertically fed as shown in FIG. 9A, in the scanning optical system 50B, the first mirror unit 57 and the second mirror unit 58 are the initial stage of scanning indicated by the broken line in the figure. A state in which a predetermined scanning range is exceeded from the position to a position indicated by a solid line at the left position in the figure, and an optical and mutual relationship between the image surface and the image pickup device CCD is maintained with respect to the imaging lens 59. Will be temporarily stopped at.

The back side image of the document D moving at the linear velocity V is scanned at the fixed position where the first mirror unit 57 and the second mirror unit 58 are set at the positions shown by the solid lines on the peripheral surface of the conveying drum 54A. The back side image is read from the front end side of the document D by the image pickup device CCD of the optical system 50B. When the reading of the back side image is completed, the first mirror unit 5 in the scanning optical system 50B is read.
7 and the second mirror unit 58 return to the initial scanning position indicated by the broken line. At the time when the document D having the front surface image facing down contacts the stop plate T and stands still on the platen glass 51, the first mirror unit 57 is scanned in the direction of arrow V at a speed of V / 2 and the second mirror unit 58 is scanned in the direction of arrow. By doing so, the optical path length optically related to each other is held, and the surface image is read by the image pickup device CCD from the front end side of the document D at the stop position.

In this way, in the image reading process of the longitudinally fed image by the image reading device 50, the front side image is read after the back side image of the original is read. When the reading of the back side image is completed, the image forming process in the color image forming apparatus described above starts. First, the read toner image of the back side image is formed on the first image bearing means (photosensitive drum 10), and then the back side toner image is transferred onto the second image bearing means (toner image receiving body 14a). .
Then, a toner image of the read front surface image is formed on the first image bearing means which has completed the transfer and cleaning. Then, the toner image of the front surface image and the toner image of the back surface image are transferred onto the transfer material (recording paper P) by the first transfer device (transfer device 14c) and the second transfer device (rear surface transfer device 14g). The fixing device 17 fixes the toner images on the front and back surfaces of the transfer material.

As a result, the images on both the front and back sides of the original D are formed on the front and back sides of the recording paper P in the same vertical direction (front end direction), and when the image data of the back side image is output to the main body of the apparatus. 9A is arranged on the back surface of the recording paper P by inverting the output for each row discharged by the electric reversing means in the main scanning direction and outputting the image signal in the reverse direction. A normal image having the same relationship as the left and right normal document images is recorded as shown in FIG.

When the image reading device 50 finishes reading the front surface image, the first mirror unit 57 and the second mirror unit 58 again move to the position shown by the solid line at the left position in the figure, and the rear surface of the next original D is read. Prepare to read images.

(Embodiment 2) An embodiment of the present invention according to claim 2 will be described with reference to FIGS.

When the original image is laterally fed as shown in FIG. 9B, in the scanning optical system 50B, the first mirror unit 57 and the second mirror unit 58 are the initial stage of scanning indicated by the broken line in the figure. A state in which a predetermined scanning range is exceeded from the position to a position indicated by a solid line at the left position in the figure, and an optical and mutual relationship between the image surface and the image pickup device CCD is maintained with respect to the imaging lens 59. Will be temporarily stopped at.

The back side image of the document D moving at the linear velocity V is scanned at the fixed position where the first mirror unit 57 and the second mirror unit 58 are set at the positions shown by the solid lines on the peripheral surface of the conveying drum 54A. The back side image is read from the rear end side of the document D by the image pickup device CCD of the optical system 50B. When the reading of the back side image is completed, the first mirror unit 5 in the scanning optical system 50B is read.
7 and the second mirror unit 58 return to the initial scanning position indicated by the broken line. At the time when the document D having the front surface image facing down comes into contact with the stop plate T and stands still on the platen glass 51, the first mirror unit 57 is moved in the arrow direction at a speed of V and the second mirror unit 58 is moved at a speed of V / 2. Then manuscript D
A surface image is read from the front end side of the image pickup device CCD. That is, the back side image is read in a form inverted in the sub-scanning direction.

In this way, in the image reading process of the laterally fed image by the image reading device 50, the front side image is read after the back side image of the original is read. When the reading of the back side image is completed, the image forming process in the color image forming apparatus described above starts. First, the read toner image of the back side image is formed on the first image bearing means (photosensitive drum 10), and then the back side toner image is transferred onto the second image bearing means (toner image receiving body 14a). .
Then, a toner image of the read front surface image is formed on the first image bearing means which has completed the transfer and cleaning. Then, the toner image of the front surface image and the toner image of the back surface image are transferred onto the transfer material (recording paper P) by the first transfer device (transfer device 14c) and the second transfer device (rear surface transfer device 14g). The fixing device 17 fixes the toner images on the front and back surfaces of the transfer material.

As a result, the image of the front and back sides of the original D is formed on the front and back sides of the recording paper P at the same left and right positions, and the image data of the back side image is reversed in the sub-scanning direction with respect to the front side image. 9B, the image signal is output in the reverse direction to the front image with respect to the front image, and the back image of the back surface of the recording paper P is output in the reverse direction as shown in FIG. 9B. A normal image having the same relationship as that of the normal original image is recorded.

When the image reading device 50 finishes reading the front surface image, the first mirror unit 57 and the second mirror unit 58 again move to the position shown by the solid line at the left position in the figure, and the back surface of the next original D is read. Prepare to read images.

(Embodiment 3) An embodiment of the present invention according to claim 3 will be described with reference to FIGS.

The determination as to whether the document is fed in the vertical or horizontal direction is performed as follows.

When the originals stacked and placed on the original table 52 shown in FIG. 8 have a length in the vertical direction longer than the length in the horizontal direction with respect to the conveying direction, they are fed vertically, and the length in the vertical direction is horizontal. If it is shorter than the length in the direction, it will be judged as lateral feed.

A vertical feed / horizontal feed detection sensor S composed of a plurality of photosensors is provided near the original table 52 along the original feed path in the direction perpendicular to the original feed path, and the vertical feed is performed by reading the surface image pattern of the original.・ Determine lateral feed. In the case of a character image, in the vertical feed, the character portion becomes horizontal stripes with respect to the ground color (white background) as shown in FIG. 9A, and in the horizontal feed as shown in FIG. 9B, the ground color (white background). ), The character portion passes through the vertical feed / horizontal feed detection sensor S in the form of vertical stripes, so that the white background portion is easily detected by the long scan in the main scanning direction or the long scan in the sub scanning direction.・ Transverse feed is determined. That is, the determination is made based on the length and frequency of this white background or black character (image portion).

FIG. 10 shows a circuit diagram in which mode switching is performed by detection of vertical feed / horizontal feed.
When the vertical feed of the document is detected by the horizontal feed detection sensor S, the control unit controls the image reading and the image forming process in the vertical feed image forming mode. Further, when the horizontal feed of the document is detected by the vertical feed / horizontal feed detection sensor S, the control unit controls the image reading and the image forming process in the horizontal feed image forming mode.

In the vertical feed image forming mode, in the scanning optical system 50B, the first mirror unit 57 is used.
The second mirror unit 58 moves from the initial scanning position shown by the broken lines 57A and 58A to a position shown by the solid line at the left position in FIG.
9, the image plane and the image pickup device CCD are temporarily stopped in a state where an optical and mutual relationship is maintained.

The back side image of the document D moving at the linear velocity V is scanned at the fixed position where the first mirror unit 57 and the second mirror unit 58 are set at the positions shown by the solid lines on the peripheral surface of the conveying drum 54A. The back side image is read from the front end side of the document D by the image pickup device CCD of the optical system 50B. When the reading of the back side image is completed, the first mirror unit 5 in the scanning optical system 50B is read.
7 and the second mirror unit 58 return to the initial scanning position indicated by the broken line. At the time when the document D having the front surface image facing down comes into contact with the stop plate T and stands still on the platen glass 51, the first mirror unit 57 has a speed of V and the second mirror unit 58 has a speed of V / 2 in the arrow direction (Fig. (Left on top)
By scanning the scanning direction, the optical path length optically related to each other is held, and the surface image is read by the image pickup device CCD from the front end side of the document D at the stop position.

In this way, in the image reading process of the longitudinally fed image by the image reading device 50, the front surface image is read after the back surface image of the original is read. When the reading of the back side image is completed, the image forming process in the color image forming apparatus described above starts. First, the read back side image is subjected to image processing in the main scanning direction, and then the toner image of the back side image is transferred to the first image carrier means (photosensitive drum 1).
0) and then the back surface toner image is transferred onto the second image bearing means (toner image receiving body 14a). Then, a toner image of the read front surface image is formed on the first image bearing means which has completed the transfer and cleaning. The first transfer unit (transfer unit 14c) and the second transfer unit (back side transfer unit 14c)
g), the toner image of the front side image and the toner image of the back side image are transferred onto the transfer material (recording paper P), and the fixing device 1
The toner images on the front and back surfaces of the transfer material are fixed by 7.

As a result, the image of the front and back sides of the document D is formed on the front and back sides of the recording paper P with the same upside down direction, and when the image data of the back side image is output to the main body of the apparatus, it is electrically changed. By inverting the main scanning direction and outputting the image signal from the opposite direction by the reverse inverting means, the same right and left original document images as shown in FIG. A regular image having a relationship of is recorded.

When the image reading device 50 finishes reading the front surface image, the first mirror unit 57 and the second mirror unit 58 again move to the position shown by the solid line at the left position in the figure and the back surface of the next original D is read. Prepare to read images.

In the horizontal feed image forming mode, in the scanning optical system 50B, the first mirror unit 57 is used.
And the second mirror unit 58 moves beyond the predetermined scanning range from the initial scanning position shown by the broken line to the position shown by the solid line at the left position in FIG. It is temporarily stopped while maintaining an optical and mutual relationship with the CCD.

The back surface image of the document D moving at the linear velocity V is scanned at the fixed position where the first mirror unit 57 and the second mirror unit 58 are set at the positions shown by the solid lines on the peripheral surface of the conveying drum 54A. The back side image is read from the rear end side of the document D by the image pickup device CCD of the optical system 50B. When the reading of the back side image is completed, the first mirror unit 5 in the scanning optical system 50B is read.
7 and the second mirror unit 58 return to the initial scanning position indicated by the broken line. At the time when the document D having the front surface image facing down comes into contact with the stop plate T and stands still on the platen glass 51, the first mirror unit 57 is moved in the arrow direction at a speed of V and the second mirror unit 58 is moved at a speed of V / 2. Then manuscript D
A surface image is read from the front end side of the image pickup device CCD. In this case, the back side image of the image data is read in a form inverted in the sub-scanning direction when the document is read.

In this way, in the image reading process of the laterally fed image by the image reading device 50, the front side image is read after the back side image of the original is read. When the reading of the back side image is completed, the image forming process in the color image forming apparatus described above starts. First, the read toner image of the back side image is formed on the first image bearing means (photosensitive drum 10), and then the back side toner image is transferred onto the second image bearing means (toner image receiving body 14a). .
Then, a toner image of the read front surface image is formed on the first image bearing means which has completed the transfer and cleaning. Then, the toner image of the front surface image and the toner image of the back surface image are transferred onto the transfer material (recording paper P) by the first transfer device (transfer device 14c) and the second transfer device (rear surface transfer device 14g). The fixing device 17 fixes the toner images on the front and back surfaces of the transfer material.

As a result, the images of the front and back sides of the original D are formed on the front and back sides of the recording paper P at the same left and right positions, and the image data of the back side image is reversed in the sub scanning direction with respect to the front side image. 9B, the image signal is output in the reverse direction to the front image with respect to the front image, and the back image of the back surface of the recording paper P is output in the reverse direction as shown in FIG. 9B. A normal image having the same relationship as that of the normal original image is recorded.

When the image reading device 50 finishes reading the front surface image, the first mirror unit 57 and the second mirror unit 58 again move to the position shown by the solid line at the left position in the figure, and the back surface of the next original D is read. Prepare to read images.

When a normal moving optical system is used for both the front and the back as a mechanism for feeding a document to the document table, it is necessary to change the method for reading the document. That is, the original is always read in such a manner that the leading edge of each image comes first when the document is fed vertically or horizontally. Further, when the image is read out from the memory storing the original and the image is output, the means for discriminating the original follows the output designation of double-sided or single-sided, vertical or horizontal, or the edit format, so that the mode can be easily switched. be able to.

In the present embodiment, when the original is read first, the transferred transfer paper can be aligned by ejecting it from the fixing device face down as shown in the image forming apparatus of FIG. This is the preferred configuration. When the original is read later, it is preferable that the transfer paper is ejected from the fixing device face up as shown in FIGS. 1 and 6 because page alignment can be performed.

[0114]

According to the present invention, the image on the front side and the back side can be efficiently transferred to the front side and the back side of the transfer material in the same state as the original, and the images on the front side and the back side are simultaneously fixed and recorded in both cases of vertical feeding and horizontal feeding of the image. It has become possible to provide a double-sided image forming apparatus capable of high-speed printing that can be performed. (Claim 1,
2) Further, according to the present invention, a double-sided image forming apparatus is provided which is extremely convenient in use and capable of high-speed printing, in which the user does not need to consider whether the image is vertically or horizontally fed. became. (Claim 3)

[Brief description of drawings]

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

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

FIG. 3 is a diagram illustrating a toner image formation state on both surfaces according to the first embodiment.

FIG. 4 is a cross-sectional configuration diagram of a second embodiment of the image forming apparatus of the invention.

FIG. 5 is a diagram showing a toner image formation state on both surfaces according to the second embodiment.

FIG. 6 is a sectional configuration diagram of a third embodiment of the image forming apparatus of the invention.

FIG. 7 is a configuration diagram of an image reading apparatus for reading a vertically or horizontally fed image.

FIG. 8 is a configuration diagram of an image reading device for reading a vertically-fed and horizontally-fed images provided with a determination unit.

FIG. 9 is a perspective view showing an example of each image pattern of a vertical feed image and a horizontal feed image.

FIG. 10 is a circuit diagram for performing mode switching according to the present invention.

[Explanation of symbols]

 10 Photoreceptor Drum 11 Scorotron Charger 12,121 Exposure Unit 13 Developing Device 14a Toner Image Receiver 14c Transfer Device 14g Backside Transfer Device 17 Fixing Device 41 Intermediate Transfer Belt P Recording Paper 50 Image Reading Device 50A Original Paper Feeding Part 50B Scanning Optical System 51 Platen glass 54A, 54B, 54C Conveying drum 55 Conveying belt 57, 57A, 57B First mirror unit 58, 58A, 58B Second mirror unit 59 Imaging lens D Original S Vertical feed / horizontal feed detection sensor CCD image sensor R Driven roller

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masakazu Fukuchi 2970 Ishikawa-cho, Hachioji-shi, Tokyo Konica stock company (72) Inventor Akiyo Matsubara 2970 Ishikawa-cho, Hachioji-shi, Tokyo Konica stock company (72) Inventor Tadayoshi Ikeda 2970 Ishikawa-cho, Hachioji-shi, Tokyo Konica Stock Company

Claims (3)

[Claims] 1. A first image bearing means for bearing a toner image formed on a surface 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 carried on the surface, first transfer means for transferring the toner image carried by the first image carrying means onto one surface of a transfer material, and It has a second transfer means for transferring the toner image carried by the second image carrying means to the other surface of the transfer material, and a fixing means for fixing the toner images transferred on both surfaces of the transfer material. In the image forming apparatus, when a double-sided image is formed on the transfer material in the longitudinal direction, a reverse unit that reverses the image data in the main scanning direction with respect to the front side image formation is formed during the back side image formation. A characteristic image forming apparatus. 2. A first image carrying means for carrying a toner image formed on the surface by the toner image forming means, and a toner image carried on the first image carrying means are collectively transferred and transferred. Second image carrying means for carrying the toner image carried on the surface, first transfer means for transferring the toner image carried by the first image carrying means onto one surface of a transfer material, and It has a second transfer means for transferring the toner image carried by the second image carrying means to the other surface of the transfer material, and a fixing means for fixing the toner images transferred on both surfaces of the transfer material. In the image forming apparatus, when a double-sided image is formed on the transfer material in a horizontal direction, a reverse unit that reverses the image data in the sub-scanning direction with respect to the front side image formation is formed at the time of the back side image formation. A characteristic image forming apparatus. 3. A first image bearing means for bearing a toner image formed on the surface by the 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 carried on the surface, first transfer means for transferring the toner image carried by the first image carrying means onto one surface of a transfer material, and It has a second transfer means for transferring the toner image carried by the second image carrying means to the other surface of the transfer material, and a fixing means for fixing the toner images transferred on both surfaces of the transfer material. An image forming apparatus, which has a discriminating unit for discriminating whether a document image to be printed is vertically fed or horizontally fed, and according to a discrimination result by the discriminating unit,
An image forming apparatus comprising an inverting means for inverting image data in a main scanning direction or a sub scanning direction with respect to a front side image when forming a back side image.