JPH1048892A - Both-side image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To record the respective images of the front and rear sides of plural originals on both sides of one recording paper by reducing it. SOLUTION: Each image data on the front and rear sides of the plural originals is compressed and is stored in an image memory 82, and a control part 80 performs the reduction of image data corresponding to a mode by a designated mode by the designation 88 of output image form, and the image data is inputted after it is sorted and assigned to the buffer memories for a front output memory 85A and a rear output memory 85B by a selector (I) 84. In the case of image-forming, the image recording of a rear image on a copy is firstly performed by data from the rear output memory 85B and next that of a front image is performed by the data from the front output memory 85A by the selector (II) 86.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to copying in which a charging means, an image exposing means and a developing means are arranged around an image carrier to transfer and fix a toner image formed on the image carrier to both sides of a transfer material. The present invention relates to an electrophotographic double-sided image forming apparatus such as a machine, a printer, and a facsimile.

[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 Application Laid-Open No. 4576/1999 proposes a method in which toner images are formed on both surfaces of a transfer material and then fixed once.

[0004]

As is well known, an image forming apparatus for forming a two-sided image using the above-described two-sided reversing sheet feeder requires a long processing distance for transferring a transfer material, so that it takes much processing time for copying. Further, since the transfer material is heated twice for fixing the image, there is a problem that paper quality is damaged.

The inventor of the present invention has previously provided two image bearing means and two transfer means to transfer a toner image to both sides of a transfer material and to simultaneously fix the transfer material having toner images on both sides. A study was made on an apparatus that performs double-sided copying, and a double-sided image forming apparatus capable of significantly increasing the processing speed of double-sided copying was realized.

The present invention provides an image forming apparatus which forms a reduced image or a part of an enlarged image on both sides of a transfer material with a predetermined layout to facilitate reading and processing of information on the transfer material. The purpose is to:

[0007]

An object of the present invention is to provide a first image carrying means for carrying a toner image formed by a toner image forming means, and a transfer of the toner image carried by the first image carrying means. A second image holding means for holding the transferred toner image on the surface, a first transfer means for transferring the toner image carried on the first image holding means to a surface of a transfer material, A two-sided image having a second transfer unit for transferring the toner image carried by the second image holding unit to the back surface of the transfer material, and a fixing unit for fixing the toner images transferred to both surfaces of the transfer material A two-sided image forming apparatus, wherein a plurality of images can be formed on the same surface of the transfer material, and images are allocated to both surfaces of the transfer material in accordance with designation of the number of images on the same surface. Device (the invention according to claim 1) and A first image holding unit that holds the toner image formed by the toner image forming unit; and a second image holding unit that transfers the toner image held by the first image holding unit and holds the transferred toner image on the surface. (2) image carrying means, first transferring means for transferring the toner image carried on the first image carrying means to the surface of the transfer material, and toner image carried on the second image carrying means And a fixing unit for fixing the toner images transferred to both sides of the transfer material in a double-sided image forming apparatus, wherein the divided image is formed on the same surface of the transfer material. This is achieved by a double-sided image forming apparatus (an invention according to claim 4) in which formation is possible and images are allocated to both sides of the transfer material in accordance with the designation of the number of divided images or the enlargement ratio. .

[0008]

Embodiments of the present invention will be described below. Note that the description in this column does not limit the technical scope of the claims and the meaning of terms. Also, the following assertive description in the embodiment of the present invention indicates the best mode, and does not limit the meaning of the terms of the present invention or the technical scope. In the following description of the embodiment, 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 and each mechanism of an embodiment of the image forming apparatus according to the present invention will be described with reference to the color image forming apparatus shown in 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. 3 is a diagram showing a transfer method of a toner image on both sides.

The photosensitive drum 10, which is an image carrier, is
A cylindrical substrate formed of a transparent member of, for example, optical glass or a transparent acrylic resin having a diameter of 120 mm is provided inside, and a photosensitive layer such as a transparent conductive layer, an a-Si layer, or an organic photosensitive layer (OPC) is provided on the substrate. And is rotated clockwise as shown by the arrow in FIG.

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 into flange members 10a and 10b at both ends on a drum shaft 110 erected and fixed to the apparatus main body, and a gear G integrated with the flange member 10b is rotatably supported. The apparatus is driven at a constant speed in a predetermined direction by being driven by meshing with a drive gear on the apparatus body side.

Scorotron charger 11 as charging means
Is used in an image forming process of each color of yellow (Y), magenta (M), cyan (C) and black (K), and is exposed in a direction orthogonal to a moving direction of the photosensitive drum 10 as an image carrier. It is installed facing the body drum 10,
A charging operation is performed by a control grid maintained at a predetermined potential with respect to the above-described organic photoconductor layer of the photoconductor drum 10 and a corona discharge having the same polarity as the toner using, for example, a sawtooth electrode as the discharge electrode 11a (this embodiment). , A uniform potential is applied to the photosensitive 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 moves an exposure position on the photosensitive drum 10 between a discharge electrode 11a of the scorotron charger 11 and a development position of the developing device 13 by a developing sleeve 131. Is provided on the upstream side in the rotation direction of the photosensitive drum.

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). Holding member 20
The exposure unit 12, the uniform exposure unit 12c, and the simultaneous transfer exposure unit 12d for each color are attached to the
Of the substrate. The image data of each color read by a separate image reading device and stored in the memory is sequentially read out from the memory, subjected to the image processing according to the present invention, and the newly edited image data of the back surface and the front surface is obtained for each color. Are input to the exposure units 12 as electric signals.

As the exposure element, 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. The light emission wavelength of the light emitting element used in this embodiment is generally high when the image exposure is performed from the outside.
A range of 0 to 900 nm is used. However, since the image is exposed from the back side, the color toner does not have sufficient translucency.
The wavelength may be m.

A developing unit 13 provided in accordance with the color sequence in which an image is formed and the rotating photosensitive drum is provided in accordance with the color sequence.
In the present embodiment, the developing units 13 of Y and M are on the left side of the photosensitive drum 10 and the developing units 13 of C and K are on the right side of the photosensitive drum 10 with respect to the photosensitive drum 10 of FIG. And the developing casing 1 of the Y and M developing units 13
The scorotron chargers 11 for Y and M are disposed below 38, and the scorotron chargers 11 for C and K are disposed above the developing casing 138 of the C and K developing devices 13.

The developing device 13 as a developing means for each color includes
One-component or two-component developers of yellow (Y), magenta (M), cyan (C) and black (K) are accommodated, respectively, and a predetermined gap is maintained with respect to the peripheral surface of the photosensitive drum 10, respectively. At the developing position, the photosensitive drum 10 rotates in the same direction as the rotating direction of the photosensitive drum 10.
m, a cylindrical developing sleeve 131 having an outer diameter of 10 to 25 mm and made of non-magnetic stainless steel or aluminum material.

The developing unit 13 is moved to a predetermined distance from the photosensitive drum 10 by an abutting roller (not shown), for example, 100 μm.
In the developing operation of the developing device 13 for each color, the developing sleeve 131 is used.
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. 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 device 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).

The image of the back and front surfaces is read as an original image by an image sensor of an image reading device separate from the present device, and is edited by a computer, and is temporarily converted into image data for each of Y, M, C and K colors. Stored and stored in memory.

When image recording is started, a gear 10G provided on the rear flange 10b of the photosensitive drum 10 is rotated through a driving gear by driving of a photosensitive member driving motor (not shown), and the photosensitive drum 10 is moved in the direction indicated by an arrow in FIG. , And at the same time, the photosensitive drum 10 is charged by the charging action of the Y scorotron charger 11 disposed below the developing casing 138 of the yellow (Y) developing device 13 to the left of the photosensitive drum 10. The application of the potential is started.

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 back side image edited on the layer is formed.

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).
An electric signal corresponding to the second color signal of the M exposure unit 12, that is, the M image data, is applied by the charging action of the magenta (M) scorotron charger 11 disposed below the third developing casing 138. Is performed, and magenta (M) is formed on the yellow (Y) toner image by non-contact reversal development by the M developing unit 13.
Are sequentially superimposed and formed.

By the same process, the developing casing 13 of the developing device 13 for cyan (C) is located on the right side of the photosensitive drum 10.
The cyan (C) toner image corresponding to the third color signal is further obtained by the cyan (C) scorotron charger 11, the exposure unit 12 of C, and the developing unit 13 of C, which are arranged above the photoconductor 8 The black (K) scorotron charger 11, the exposure unit 12, and the developing device 13 are arranged on the right side of the drum 10 and below the developing casing 138 of the black (K) developing device 13 at the lower part of the fourth color by the fourth unit. A black (K) toner image corresponding to the signal is sequentially superposed, and a color toner image is formed on the peripheral surface within one rotation of the photosensitive drum 10 (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 the same exposure as the image corresponding to the first color signal is performed. 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 surface image is formed on the photosensitive drum 10 (first image carrying means) serving 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 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 rubber material in contact with
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. Also, since the back side image is once transferred onto the second image carrier and then transferred onto the transfer material,
On the transfer material, the image density of the back side image is lower than that of the front side image. Therefore, the image formation is performed under conditions such that the image forming process conditions such as charging, image exposure, and development are changed so that no difference is observed in the image density on the transfer material.

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 a paper charger 14f as a transfer material charging means, is attracted to the toner image receiver 14a, and is fed to the transfer area 14b. By charging the paper with the same polarity as the toner, it is possible to prevent the recording paper P from attracting the toner image on the toner image receiver or the toner image on the image carrier outside the transfer section, thereby preventing the toner image from being disturbed. doing. 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 the present 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 with each other, it is preferable that the toner in the upper layer and the toner in the lower layer of the toner layer are charged with the same charge amount and the same polarity 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.

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 toner filming prevention layer of 10 ¹⁰ to 10 ^{16 on} the outside of the rubber substrate. Ω · cm thickness 5-50μm
And a two-layer structure with fluorine coating. 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 to 0.5 mm can 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 brought into contact with and abuts on 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. 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 a cleaning device 19 or is made of a rubber material that abuts on the photoconductor drum 10. Cleaning device 1 by cleaning blade 19a
9 and is collected by a screw 19b into a waste toner container (not shown). The photosensitive drum 10 from which the residual toner has been removed by the cleaning device 19 is uniformly charged by the Y scorotron charger 11, and enters the next image forming cycle.

By using the above-described method, since the superimposed color toner images are transferred collectively, color shift of the color image on the toner image receiving member, scattering or rubbing of the toner, and the like are less likely to occur, and the image is less deteriorated. A double-sided color image is formed.

The image data of each color of the document input to the color image forming apparatus is read by, for example, an image reading device 50 provided separately from the main body of the apparatus shown in FIG.

In the case of the image reading apparatus 50 described above, the originals D are stacked in page order from the lower side with the front surface facing downward, and the lowermost original D is directed to the transport path 53 by the operation of the discharge belt 51 and the separating roller 52. It is carried out.

The conveyed original document D is retracted to the position shown by the broken line without the guide plate G biased to the position shown by the solid line, and is placed on the transparent platen glass 55 via the transport belt 54. The document is fed, and is temporarily stopped at the document reading position with the back face down.

The back side image of the original D on the platen glass 55, that is, page 2 of the first original, is positioned in a V-shape with a first mirror unit 56 comprising an illumination lamp and a first mirror constituting a scanning optical system. The second mirror unit 57 composed of the second mirror and the third mirror is read by the reading operation at the speed V of the first mirror unit 56 and the moving exposure by the second mirror unit at the speed V / 2 in the same direction. The image is formed on the image sensor CCD by the projection lens L. The back surface image formed on the image sensor CCD is compressed image data and stored in an image memory as image data for each color.

When the reading of the back side image is completed in the image reading device 50, the original D is turned upside down through the reversing sheet feeding path 58 by the temporary reverse rotation of the conveying belt 54, and again passed through the conveying path 53 to the conveying belt 54. Through the platen glass 5
5, and is temporarily stopped at the document reading position with the front surface facing downward.

The original D on the platen glass 55 is read from the front side image, that is, page 1 of the first original by the scanning optical system, and the image data is compressed and stored in the image memory as image data for each color. .

Subsequently, in the same manner, each original D
Are read in the order of page 4, page 3, page 6, page 5,..., And the compressed image data is arranged in the page memory in the order of page 1, page 2, page 2, and so on. 3, page 4... Are sequentially stored.

In general double-sided image formation, each image data stored in the image memory 82 is output to a printer unit as an image forming unit of the apparatus through a data output control process shown in FIG.

In the case of normal double-sided printing, each image data stored in the image memory 82 is converted into page 1, page 2, page 3,
.. Are called in the order of page 4, page 5, page 6,..., And the compressed image data is restored, and the selector (I) 84 selects page 1, page 3, page 5,.
The image data of the odd-numbered pages is stored in the front-side output memory 85A.
.. Are stored in the buffer memory of the backside output image memory 85B.

As the image data stored in the output memories, the selector (II) 86 alternately outputs the front and back image data of each document D, and outputs image data such as color correction and gamma correction according to the printer. After the processing is performed by the image processing section 87, the image is output to the exposure unit 12 of the printer section. Also, when forming the front and back images, charging, exposure,
Image forming conditions such as development or transfer conditions are switched, and process control is performed so that image densities on a copy become substantially equal, and double-sided image formation is performed. Also, since the front and back images need to be mirror images on the image forming body, it is necessary to mirror the back images when transferring image data from each output memory to the printer. It is.

The back side image formed on the toner image receiver 14a and the front side image formed on the photosensitive drum 10 are the front and back of the first recording paper P fed from the paper feed cassette 15. And the first copy cycle is completed. The recording paper P holding the front side toner image and the back side toner image is fixed by the fixing device 17 and is turned upside down and discharged onto a tray outside the apparatus with the front side down.

For the second and subsequent copies, the image data from the back side output image memory 85B is output by outputting the image data from the back side output image memory 85B, and the image data from the front side output image memory 85A is output. Thus, the front side image and the back side image are transferred to the front and back of each of the second and subsequent recording sheets P fed from the sheet feeding cassette 15. The recording paper P holding the front toner image and the rear toner image is fixed by the fixing device 17, and is stacked in a page order on the recording paper discharged first with the front side down.

On the other hand, in the image reading device 50, the originals D for which the image reading has been completed are stacked on the tray 60 via the discharge rollers 59 by the operation of the transport belt 54, with the front surface facing down, in the order of pages from below. Paper is discharged as follows.

(Embodiment 1) The invention according to claims 1 to 3 will be described with reference to FIGS.

When the front and back images of a plurality of originals D are reduced and formed on both the front and back surfaces of one sheet S of the recording paper P, a plurality of output image forms are prepared in advance, and the corresponding front and back surfaces are prepared. An output image mode in which front and back images of a plurality of originals are reduced and formed is selected and designated by an output image form designation 88. At this time, if it is desired to provide a margin on the sheet, this is also included in the selection conditions. The control unit 80 determines from the memory 89 an image reduction condition corresponding to the output image mode,
The layout conditions for the front side or the back side are called, whereby the image data of the access page described on the front side and the back side of the first sheet on the sheet are sequentially called from the image memory 82. Next, a reduction process is performed by the image processing unit 83 'according to the reduction condition. Restoration of the reduced image data according to the allocation conditions is performed by the image data restoration unit 83 and the image processing unit 83 '.
The image data restored to the predetermined size is output to the buffer memory of the front-side output memory 85A or the back-side output memory 85B in accordance with an instruction as to which position on the front side or the back side is allocated. As described above, reading from the image memory 82 and development to the output memory 85 are repeated, and image data necessary for output is formed on the output memory 85. In this way, the reduced image data is allocated and stored on the front and back surfaces of the first sheet on the sheet.

As shown in the example of FIG. 6A, when each image on the front and back of the same original is recorded in a reduced form on the same portion on the front and back of the sheet S, this output image mode is set to the output image mode. The designation 88 is selected and designated. At this time, an instruction to provide a margin on the sheet S is also issued. Control unit 8
0 calls out a condition for reducing the image in the designated mode and a condition for allocating the image to the front surface or the back surface in the designated mode from the memory 89, thereby performing data processing of the image. First, the image data of the back side of each document D, that is, the image data of the second page, the fourth page,.
2 are sequentially called from the image data, and the data reduced to a predetermined reduction rate by the restored image processing unit 83 ′ in the image data restoration 83 is
The frame positions K2, K4,.
-Allocated to K12 and stored in the back side output memory 85B.

Next, the image data of the front side of each document D, that is, the image data of the first page, the third page,..., The eleventh page is sequentially read out from the image memory 82, restored by the image data restoration 83, and The data reduced to the same predetermined reduction ratio by the processing unit 83 'is allocated to the frame positions K1, K3,..., K11 by the selector (I) 84 and stored in the surface output memory 85A. At this time, the top and bottom frame positions (K1, K2), (K3, K
4) respectively correspond.

At the time of output, the selector (II) 86 calls back surface image data from the back surface output memory 85B, and subsequently reads back surface image data from the front surface output memory 85A. The processing is performed, and image exposure is performed in the printer unit. In the image processing unit 87, a difference is made between the color correction amount and the γ correction amount between the back side image and the front side image, and correction is performed so that the image quality of the front and back sides on the sheet is the same. In particular, the image density of the back side image is lower than that of the front side image because the transfer is performed twice. It is necessary to set the maximum amount of toner adhering on the photoreceptor to about 5 to 20% larger by a process for increasing the photoreceptor potential, contrast, and developability. In color, color correction is necessary because the color superposition order is reversed.

Since the plurality of images on both sides of the sheet S on which the double-sided image is formed correspond to the images on the front and back sides of the document D, the margins are cut out as indicated by broken lines to obtain K1, K3,. When the pages are superimposed in the order of K11, the page order of the document D is reproduced, so that bookbinding can be performed in that state.

When the images on the front and back of the same original are recorded in parallel on either the front or back of the sheet S as in the example shown in FIG. 6B, this output image mode is set to the output image mode. Is selected / specified by the specification 88 of. At this time, designation of providing a margin on the sheet S is also performed. Control unit 8
0 calls from the memory 89 the conditions for reducing the image in this designated mode and the conditions for allocating the image to the front surface or the back surface, whereby the data processing of the image is performed. First, the image data of the ninth page, the tenth page,..., The sixteenth page, which corresponds to the latter half of the original, are sequentially called from the image memory 82,
After the image data is restored by the image data restoration 83, the data reduced to a predetermined reduction ratio by the image processing unit 83 'is stored in the back surface output memory 85B by the selector (I) 84 and the frame positions K9 and K1 are stored.
0 ... K16 and stored.

Next, the image data of the first page, the second page,..., The eighth page corresponding to the first half of the original are sequentially retrieved from the image memory 82, and the data reduced to a predetermined reduction ratio by the image data restoration 83 is The selector (I) 84 stores the frame positions K1, K2,.
.. Memory is allocated to K8.

At the time of output, the selector (II) 86 alternately outputs back side image data from the back side output memory 85B and then front side image data from the front side output memory 85A. On the sheet S on which the images are recorded, the front and back images of the same document are recorded on the same surface in the order of pages, so it is convenient to compare the front and back images or read in the page order, and the images are formed in this manner. It is also possible to bind a plurality of sheets S in the page order of the document D and to perform bookbinding in a reduced form.

As for the image data, the front or back data may be alternately read from the image memory 82, reduced, and alternately stored in the output memories 85A and 85B.

(Embodiment 2) The invention according to claims 4 to 6 will be described with reference to FIGS.

A part of the front and back images of one document D is divided and recorded on both sides of each of the plurality of sheets S of the recording paper P, and the sheets S are connected to each other. In the case of enlarging and recording an image, a plurality of output image forms are prepared in advance, and a part of the front and back images of one document is divided and enlarged and formed on a corresponding plurality of front and back surfaces. The image mode is selected and designated by the designation 88 of the output image form. At this time, if it is desired to provide a margin on the sheet, this is also included in the selection conditions. The control unit 80 calls the image division and enlargement conditions corresponding to the corresponding output image mode and the layout conditions for the front surface or the back surface from the memory 89, and based on these, reads the first image on the sheet from the image memory 82. The image data of the access page recorded on the front side and the back side is called, restored by the image data restoring unit 83, and then divided and enlarged by the image processing unit 83 'to perform the front side output memory 85A or the back side output memory 85B. Is stored in the buffer memory in which the position is allocated.

As an example, as shown in FIG.
When the front side image is divided into four parts (1A to 1D) and the back side image is divided into four parts (2A to 2D) and enlarged and recorded corresponding to the front and back sides, the control unit 80 first stores the back side image data from the image memory 82. And the upper right image data (2C) divided into four after restoration in the image data restoration 83 is selected and enlarged in the image processing unit 83 ', and the selector (I)
As a result, a memory location is allocated to the back surface output memory 85B and an output is made.

Next, the surface image data is called from the image memory 82, the upper left image data (1A) divided into four parts after restoration in the image data restoration 83 is selected and enlarged in the image processing section 83 ', and the surface data is selected by the selector (I). An output is made to the output memory 85A. Selector (II)
At 86, first, the back side image data (2C) and then the front side image data (1A) are called up to form an image, and the front side image (1A) and the back side image (2) are placed on the front and back of the sheet (S1).
C) is formed.

Subsequently, the back surface output memory 85 is similarly operated.
B stores the image data of the lower right area (2D) of the back side document image, and the front side output memory 85A stores the image data of the lower left area (1B) of the front side document image. In the selector (II) 86, the back side image data (2D) is first called, and then the front side image data (1B) is called to form an image, and images (1B, 2D) are formed on the front and back of the sheet (S2). Similarly, images (1D, 2B) are formed on the front and back of the sheet (S3), and images (1C, 2A) are formed on the front and back of the sheet (S4).

As shown in FIG. 7 (b), the sheets S are overlapped with and joined to the margins (shown by diagonal lines) which are in contact with each other, so that the images on the front and back of the document D are enlarged and one sheet is formed. The layout is formed on a large-sized sheet with the same layout.

[0069]

According to the present invention, according to claim 1,
It is possible to reduce and record the images of the front and back of a plurality of originals on both sides of the recording paper, and enlarge and record the images of the front and back of the original on both sides of a large recording paper according to claim 4. Claims 2 and 5 allow the images to be recorded in page order or in the same layout. Claims 3 and 6 allow the front and back images to be recorded regardless of the difference in the transfer process and the reduction or enlargement of the image. Thus, a high-performance double-sided image forming apparatus has been provided which automatically corrects image forming conditions and can always record a high quality image.

[Brief description of the drawings]

FIG. 1 is a cross-sectional configuration diagram of a two-sided image forming apparatus of the present invention.

FIG. 2 is a side sectional view of an exposure unit of the photosensitive drum.

FIG. 3 is an explanatory diagram showing an image transfer method.

FIG. 4 is a cross-sectional configuration diagram of a document reading device.

FIG. 5 is an input / output control circuit diagram of image data.

FIG. 6 is an explanatory diagram showing allocation of reduced images.

FIG. 7 is an explanatory diagram showing allocation of an enlarged image.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Photoconductor drum 11 Scorotron charger 12 Exposure unit 13 Developing device 14a Toner image receiver 14c Transfer device 14f Paper charger 14g Back transfer device 15 Paper cassette 17 Fixing device 18 Discharge roller 19 Cleaning device 50 Image reading device D Document P Recording paper

Claims (6)

[Claims] A first image carrying means for carrying the toner image formed by the toner image forming means; and a toner image carried by the first image carrying means is transferred. A second image carrying means carried on the surface; a first transferring means for transferring the toner image carried on the first image carrying means onto a surface of the transfer material; and a carrying means carried on the second image carrying means. A two-sided image forming apparatus, comprising: a second transfer unit for transferring the transferred toner image to the back surface of the transfer material; and a fixing unit for fixing the toner image transferred to both surfaces of the transfer material. A double-sided image forming apparatus, wherein a plurality of images can be formed on a surface, and images are allocated to both surfaces of the transfer material in accordance with designation of the number of images on the same surface. 2. An apparatus according to claim 1, wherein said apparatus has an image memory for a front side and an image memory for a back side, and performs selective transfer of a plurality of reduced image data to each of said memories and alternate output from said memory to a printer unit. The double-sided image forming apparatus according to claim 1, wherein: 3. The double-sided image forming apparatus according to claim 1, wherein image forming conditions are different between the front side image and the back side image. 4. A first image carrying means for carrying a toner image formed by a toner image forming means, and a toner image carried by the first image carrying means is transferred. A second image carrying means carried on the surface; a first transferring means for transferring the toner image carried on the first image carrying means onto a surface of the transfer material; and a carrying means carried on the second image carrying means. A two-sided image forming apparatus, comprising: a second transfer unit for transferring the transferred toner image to the back surface of the transfer material; and a fixing unit for fixing the toner image transferred to both surfaces of the transfer material. A double-sided image forming apparatus, wherein a divided image can be formed on a surface, and images are allocated to both sides of the transfer material in accordance with designation of the number of divided images or an enlargement ratio. 5. An image memory for a front side and an image memory for a back side, wherein selective transfer of a part of enlarged image data to each memory and alternate output from each memory to a printer unit are performed. The double-sided image forming apparatus according to claim 4. 6. The double-sided image forming apparatus according to claim 4, wherein image forming conditions are different between the front side image and the back side image.