JP3393288B2 - Double-sided image forming device - Google Patents

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 toner image formed on an image carrier is transferred and fixed on both sides of a transfer material by arranging a charging unit, an image exposing unit and a developing unit around the image carrier. The present invention relates to an electrophotographic double-sided image forming apparatus such as a machine, a printer, and a FAX.

[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, which is once housed in a double-sided reversing paper feeder and then image-carried again. A method is used in which a transfer material is fed from a double-sided reverse paper feeding device in time with an image formed on the body, and the image on the other surface is transferred and fixed on the transfer material.

As described above, in this double-sided copying apparatus, since the transfer material is fed to the double-sided reversal sheet feeding apparatus and is passed through the fixing device twice, the reliability of the transfer material is low and the jam occurs. It was a cause of causing such. On the other hand, JP-B-49-37538, JP-B-54-28740, JP-A-1-44457, and JP-A-4-214576 are used to form a toner image on both surfaces of the transfer material, and then fixing is performed once. Things have been proposed.

[0004]

As is well known, an image forming apparatus for forming a double-sided image using the above-mentioned double-sided reversal sheet feeding apparatus requires a long processing time for copying because the transfer material conveying distance is long. Further, 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 have realized a double-sided image forming device that can significantly increase the processing speed of double-sided copying.

However, a drum-shaped photosensitive member and a belt-shaped intermediate transfer member are used as the above-mentioned two image-bearing means, and while the transfer material is being conveyed by the intermediate transfer member, both surfaces of the photosensitive member are transferred onto the photosensitive member. Since the process of sequentially transferring the front side image and the back side image on the intermediate transfer body is performed, the transfer material conveyance distance becomes long. Therefore, even if the transfer material slightly moves during the transfer material conveyance, the toner on the intermediate transfer body The image may be disturbed and the image quality may be deteriorated.

As a result of solving this problem and improving the present invention, by improving the relational position between the photosensitive member and the intermediate transfer member, the feeding position of the transfer material, etc., the transfer distance of the transfer material is shortened and the intermediate position is reduced. It is an object of the present invention to provide a double-sided image forming apparatus capable of preventing the toner image on the transfer body from being disturbed and shortening the copy time.

[0008]

The above object is to provide a first image bearing means for bearing a toner image formed by a toner image forming means, and a toner image carried on the first image bearing means. A second image carrying means for carrying the transferred toner image on the surface, a first transfer means for transferring the toner image carried by the first image carrying means onto the surface of a transfer material, a second transfer means for transferring the toner image carried on the second image bearing means on the rear surface of the transfer material, the rolling
In a double-sided image forming apparatus having a static eliminator for separating a copying material from the second image carrying means, and a fixing means for fixing the toner images transferred on both surfaces of the transfer material, the first image carrying means is The drum-shaped image forming body and the second image carrying means are belt-shaped toner image receiving bodies, and the toner image receiving body is stretched in the vertical direction by a pair of roller members arranged in the vertical direction. , The first transfer means above the intermediate position of the upper and lower belt lengths, and the upper roller member
To the position opposite to the static eliminator, the first transfer means and the front.
The second transfer means is provided between the static eliminator and
The first transfer means carries the image on the first image carrying means.
After transferring the toner image on the surface of the transfer material,
The image is carried on the second image carrying means by the second transfer means.
Transfer the toner image onto the back surface of the transfer material to remove the static electricity.
Before transferring the toner image on both sides from the toner image receiver
Double-sided image forming apparatus characterized by separating the serial transfer material (invention according to claim 1), thus being achieved.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Prior to the description of the embodiments of each invention, the structure and function of a double-sided image forming apparatus will be described with reference to FIGS.
Explained by.

Reference numeral 10 denotes a photosensitive drum which is a first image bearing means, for example, an OPC photosensitive member coated on the drum, and is driven and rotated in a clockwise direction in a grounded state. 11
Is a scorotron charger, and in this embodiment, the peripheral surface of the photoconductor drum 10 is negatively and uniformly charged by a corona discharge by a grid held at a predetermined potential and a corona charging wire to give a potential of V _H.

After the photosensitive drum 10 is charged, the laser writing device 12 is provided with a document reading device or a memory (I) described later.
The image data of the back side image of the original is input as a signal, and the formation of a latent image is started.

The laser writing device 12 uses a laser diode (not shown) as a light emitting source to rotate the polygon mirror 1.
Main scanning is performed via 2A, the fθ lens 12B, and the reflecting mirror 12C, and sub-scanning is performed by rotation of the photoconductor drum 10 to form a latent image on the photoconductor drum 10. In this embodiment, the absolute value of the potential in the exposed portion is V _{L which} is lower than V _H.
And a latent image is formed.

On the peripheral surface of the photosensitive drum 10, there is provided a developing device 13 containing a developer composed of, for example, black toner and a magnetic carrier, and has a magnet body inside to hold the developer. Reversal development is performed on the latent image by the rotation of the developing sleeve 13A. The developer is regulated to have an appropriate layer thickness on the developing sleeve 13A and conveyed to the developing area, where the developing sleeve 13A and the photosensitive drum 10 are connected.
The toner having a negative polarity is _VL on the side of the photoconductor drum 10 by the negative DC voltage V _DC applied between
The latent image portion of the electric potential of is attached to visualize the image.

In this way, the toner image of the back side image of the original formed on the photosensitive drum 10 is applied with a DC voltage of the opposite polarity to the toner by the transfer device 14 as the first transfer means, and the second image carrying means. Is transferred onto the peripheral surface of the toner image receiver 15. The toner image receiver 15 has a thickness of 0.5 to 2.
An endless rubber belt of 0 mm, a semi-conductive 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 having a thickness of 5 to 10 μm on the outer side of the rubber substrate. It has a two-layer structure in which the above-mentioned fluorine coating is applied. This layer is also 10 ¹⁰ to 10 ¹⁶ Ω.
A semiconductivity of cm is preferred. 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 toner image receiver 1
5 is a drive roller 1 by pressing the tension roller 15A.
5B and the driven roller 15C are stretched in the up-down direction, and while the peripheral surface of the driven roller is in contact with the photoconductor drum 10, the drive roller 15B is rotated to rotate counterclockwise in synchronization with the peripheral speed of the photoconductor drum 10. It is circulated and conveyed. The drive roller 1
5B and the driven roller 15C are grounded.

The photosensitive drum 10 which has been transferred to the toner image receiving body 15 is cleaned by removing the residual toner by the cleaning device 100, and subsequently, the potential of V _H is applied by the scorotron charger 11 and then the laser writing device. The exposure scanning of 12 continuously forms and transfers the toner image of the back side image of the document.

When the formation and transfer of the toner image on the entire backside image is completed by a plurality of rotations of the photosensitive drum 10, the image data of the front side image of the original is called from the memory (II) described later and input as a signal. The formation of the toner image of the surface image is started on the photoconductor drum 10.

The toner image of the front surface image is synchronized with the toner image of the back surface image formed on the toner image receiving body 15 previously formed, and the photosensitive drum is subjected to the same process as in the case of forming the toner image of the back surface image. Formed on 10. The image data is converted so that the toner image of the front surface image formed at this time becomes a mirror image of the toner image of the back surface image previously formed.

The recording paper is unloaded from the paper feed cassette 16 in parallel with the formation of the toner image of the front surface image, and is synchronized with the toner images on the photosensitive drum 10 and the toner image receiving body 15 by the operation of the timing roller 17. Will be fed.

The recording paper is charged to the same polarity as the toner by the paper charger 18, adsorbed on the toner image receiving body 15 and fed as a unit, and is transferred to the upper surface of the surface of the photosensitive drum 10 by the transfer device 14. The toner image of the image is transferred.

Next, the recording paper is charged to the opposite polarity to the toner in the back surface transfer device 19 provided as a second transfer means, and the toner image of the back surface image on the toner image receiving body 15 is transferred to the lower surface thereof.

The recording paper on which the toner images have been transferred to the upper and lower surfaces in this way is neutralized by the static eliminator 20 and the toner image receiver 15 is then discharged.
The recording paper that is separated further and moves up and down is the fixing device 21.
The toner is heated from both the left and right sides by the nip conveyance of the fixing roller 21A and the pressure-bonding roller 21B to fuse the toner, and then the toner is ejected onto the tray 23 via the paper ejection roller 22.

Photoreceptor drum 10 after transfer of the toner image
Removes the residual toner in the cleaning device 100, while the toner image receiving body 15 is cleaned of the residual toner in the cleaning device 150 with the blade 150A in a pressure contact state to prepare for the formation of the toner image of the back surface image of each subsequent document.

The image data for each color of the original document input to the above-mentioned double-sided image forming apparatus is read by an image reading apparatus 50 provided separately from the apparatus main body 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 side facing down, and the operation of the carry-out belt 51 and the separating roller 52 directs the lowermost original D to the conveying path 53. Be shipped.

The carried-out document D is retracted to the position shown by the broken line by removing the guide plate G biased to the position shown by the solid line, and placed on the transparent platen glass 55 via the conveyor belt 54. After being fed, it is temporarily stopped at the document reading position with the back side facing downward.

The back side image of the document D on the platen glass 55 is a second mirror positioned in a V-shape and a first mirror unit 56 including an illumination lamp and a first mirror which form a scanning optical system.
A second mirror unit 57 including a mirror and a third mirror
Of the reading operation at the speed V of the first mirror unit 56 and the speed V / 2 in the same direction by the second mirror unit.
Is read by the moving exposure by the image pickup device, and an image is formed on the image pickup device CCD by the projection lens L. The back side image formed on the image pickup device CCD is temporarily stored as image data in the image memory (I) and is output to the laser writing device 12 as an electric signal to be photoconductor drum 10.
The latent image is formed on the toner image, and the toner image formed after the development is transferred by the transfer device 14, and the back surface image is formed on the toner image receiver 15.

When the image reading device 50 finishes reading the back side image, the document D is turned upside down through the reversing paper feed path 58 by the temporary reverse rotation of the conveyor belt 54, and again through the conveyor path 53 and the conveyor belt 54. Through platen glass 5
The paper is fed onto the sheet 5 and is temporarily stopped at the document reading position with the front side facing downward.

The original image D on the platen glass 55 has its surface image read by the scanning optical system, is temporarily stored in the image memory (II) as image data for each color, and an electric signal is sent to each laser writing device 12. And the surface image is formed on the photosensitive drum 10 as described above.

When copying the second and subsequent sheets, the image of the original D is not read, and the back side image is output from the image memory (I) by outputting the image data from the image memory (I). A surface image is formed by outputting the image data.

On the other hand, in the image reading apparatus 50, the originals D for which the image reading has been completed are stacked in order from the lower side in the page order with the front side facing down on the tray 60 via the discharge rollers 59 by the operation of the conveying belt 54. Is ejected.

(Embodiment 1) An embodiment of the invention according to claims 1 and 2 will be described with reference to FIG.

In the double-sided image forming apparatus of the present invention, the photosensitive drum 10 is located at an intermediate position of the belt length above and below the belt surface which moves above the toner image receiving body 15 stretched in the vertical direction. The transfer device 14 that is in contact with the belt surface adjacent to the driven roller 15C located at an upper position, that is, the transfer roller 14 that transfers the surface toner is provided so as to face the drum surface. The distance between the rear surface transfer device 19 provided opposite to the belt surface for transferring the rear surface toner image and the separation position by the static eliminator 20 is reduced, and the toner image receiving body 15 is conveyed in close contact with it. The conveyance distance of the recording paper P that is used is significantly shortened. As a result, the disorder of the toner images on the front and back surfaces transferred onto the recording paper is hardly recognized. On the other hand, when the contact position is below the intermediate position, the toner image is disturbed before and after the transfer.

The most appropriate contact position of the photosensitive drum 10 with respect to the toner image receiver 15 is the photosensitive drum 1.
When the photosensitive drum 10 having a small drum diameter is used, the belt length L is more than 1 from the midpoint M of the belt which is stretched in the vertical direction, although it depends on the drum diameter of 0.
It is possible to set the contact position above / 10 to 4/10, and therefore, the paper feed position of the recording paper P can be set near the intermediate point M. The total feeding distance of the recording paper P until the separation after the transfer is also remarkably shortened.

As a result, the toner image receiving body 15 becomes the recording paper P.
Since the contact time with the toner is extremely short, the possibility that the toner image of the front surface image on the belt is disturbed by the recording paper P before transfer is extremely small, and the back surface transfer device 19 transfers and records it as a high quality image. It will be.

Further, the toner image receiving body 15 is cleaned in a space below the photosensitive drum 10 on the side of the toner image receiving body 15 which is generated by setting the paper feeding position near the intermediate point M on the belt surface. Cleaning device 1
50, and the double-sided image forming apparatus can be made more compact by arranging the paper feed cassette 16 of the recording paper P for feeding paper to the paper feed position.

(Embodiment 2) An embodiment of the invention according to claims 3 to 5 will be described with reference to FIG.

In the double-sided image forming apparatus of the present invention, the photoconductor drum 10 is in contact with the belt surface which moves upward from the central position in the vertical direction of the toner image receiving body 15 stretched in the vertical direction. The contact position of the recording paper P, that is, the paper feed position N relative to the belt surface, is higher than the drive roller 15B for driving the toner image receiving body 15 which is a lower roller member, preferably the drive roller 158. It is provided more sufficiently near the intermediate portion of the belt surface to reduce the total feeding distance from the feeding of the recording paper P to the belt surface to the transfer of the front surface toner image and the back surface toner image and separation. Thus, the disturbance of the toner image of the back side image on the toner image receiving body 15 due to the conveyance of the recording paper P is suppressed to the minimum.

Further, by disposing the above-mentioned paper feeding position N near the intermediate portion of the belt surface of the toner image receiving body 15 stretched in the vertical direction, the space of the belt surface formed between the drive roller 15B and It is possible to install the cleaning device 150 for the toner image receiving body 15 and to house the paper feeding cassette 16 below the photoconductor drum 10 on the side of the belt surface thereof, thus realizing a compact device. To be done.

Further, in the cleaning device 150, the distance on the belt surface to the transfer device 14 is smaller than the distance on the peripheral surface of the photosensitive drum 10 from the transfer device 14 to the exposure position Q of the laser writing device 12. It is possible to avoid releasing the pressure contact of the blade of the cleaning device 150 during the exposure of the image. In other words, it is possible to prevent the peripheral speed of the photosensitive drum 10 from becoming abnormal due to the shock of the drum caused by the pressure release of the blade of the cleaning device 150, and the disturbance of the image formed by the image exposure.

The photosensitive drum 10 on the side of the belt surface
By arranging the paper feed cassette 16 in the lower position of
Not only can space be effectively used and compactness can be achieved, but the length of the paper feed path from the paper feed cassette to the paper feed position N is set to be extremely short, and jams and the like that may occur during paper feed. Accidents will be greatly reduced.

(Embodiment 3) An embodiment of a reference example of the present invention will be described with reference to FIG.

In the double-sided image forming apparatus of the present invention, the toner image receiving body 15 stretched between the driven roller 15C and the driving roller 15B located above and below is the transfer device 1.
4, a cleaning device 150, a belt side guide plate 160 forming a paper feed guide member for the recording paper P provided between the paper feed cassette 16 and the timing roller 17,
U-shaped frame body 200 in which front and rear side plates are connected and integrated
It is installed in the main body of the device while being supported by.

The frame body 200 is rotatable in a counterclockwise direction around a fulcrum 200A coaxial with the rotation axis of the drive roller 15B as a center of rotation. The respective members supported by the frame body 200 including the toner image receiving body 15 locked to the plywood board 200B are set to positions where image formation is possible. At the position where the image can be formed, the photosensitive drum 10 and the toner image receiving body 15 are in contact with each other.

Further, the apparatus main body is provided with an openable door 300 on a side surface facing the frame body 200, and is configured to be opened counterclockwise through a fulcrum 300A, and via a lock lever 300D. It is locked to the side wall 300B of the apparatus main body and closes the side surface of the apparatus main body during image formation.

The door 300 corresponds to the lock lever 3 described above.
By rotating 00D, the engagement with the side wall 300B of the main body of the apparatus is released and the door is opened at a substantially right angle from the position shown by the solid line in the figure to the position shown by the alternate long and short dash line.
When 00 is opened, the lock lever 200D of the frame body 200 is further rotated to release the engagement with the engagement plate 200B, and the frame 200 has a dashed line from the position shown by the solid line in the figure. The inside is opened by being rotated in a direction substantially perpendicular to the position shown.

As a result, the conveying surface of the recording paper P is opened over a wide range from the guide plate 160 through the image transfer area to the back surface transfer device 19 and the static eliminator 20, so that the jam treatment and other maintenance can be performed. It can be done easily and accurately.

Further, by adopting a structure in which the process unit including the photoconductor and the developing device can be replaced from this open state, simplification of maintenance can be realized.

[0048]

According to the present invention, it is possible to provide a compact and practical double-sided image forming apparatus which requires a small floor area for installation, and according to claims 1 and 2, the recording paper of the toner image receiving body can be used. The close-contact conveying distance is shortened to reduce the disturbance of the toner image before transfer, and a space below the paper feeding position of the recording paper is generated according to claim 3, and the cleaning device (claim 4) and the paper feeding cassette (claim Item 5) can be accommodated, the apparatus can be made more compact, and the paper feed path can be shortened to prevent jams and other recording paper conveyance defects. Further , according to the reference example of the present invention, the recording paper conveyance surface There opened jam treatment, other maintenance is facilitated, and with wider becomes jam processing operation opening the more conveying surface to release the opening of the paper guide member is made very easy,
Processing more waste toner release integral opening of the cleaning device also was to be made easily.

[Brief description of drawings]

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

FIG. 2 is a cross-sectional configuration diagram of a document image reading device.

FIG. 3 is an explanatory diagram showing a contact position of a photosensitive drum with respect to a toner image receiving body.

FIG. 4 is an explanatory view showing a feeding position of a recording sheet with respect to a toner image receiving body.

FIG. 5 is an explanatory diagram showing an open configuration of a toner image receiving body.

[Explanation of symbols]

10 Photosensitive drum 11 Scorotron charger 12 Laser writing device 13 Developer 14 Transfer device 15B drive roller 15C driven roller 16 paper cassettes 17 Timing roller 18 Paper charger 19 Back transfer device 20 Static eliminator 50 image reader 100,150 cleaning device 160 information board 200 frame 300 doors 200D, 300D lock lever

Front page continuation (72) Inventor Akiyo Matsubara 2970 Ishikawa-cho, Hachioji, Tokyo Konica stock company (72) Inventor Mawa Fukuchi 2970 Ishikawa-cho, Hachioji, Tokyo Konica stock company (56) Reference Documents JP-A-4-130387 (JP, A) JP-A-6-110288 (JP, A) JP-A-7-191515 (JP, A) JP-A-4-303851 (JP, A) JP-A-2- 306262 (JP, A) JP 4-76563 (JP, A) JP 2-248962 (JP, A) JP 4-214576 (JP, A) JP 8-292617 (JP, A) JP-A-3-21973 (JP, A) JP-A-9-211900 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03G 15/00 G03G 15/01 G03G 15/14 -15/16 G03G 21/16-21/18

Claims (5)

(57) [Claims] 1. A first image bearing means for bearing a toner image formed by a toner image forming means, and a toner image carried on the first image bearing means is transferred to the transferred toner image. Second image carrying means for carrying on the surface, first transfer means for transferring the toner image carried on the first image carrying means to the surface of the transfer material, and carrying on the second image carrying means Second transfer means for transferring the formed toner image to the back surface of the transfer material, and a static eliminator for separating the transfer material from the second image carrying means.
And a fixing means for fixing the toner images transferred on both sides of the transfer material, wherein the first image carrying means is a drum-shaped image forming body,
The image bearing means is a belt-shaped toner image receiving body, and the toner image receiving body is a pair of roller portions arranged vertically.
It is stretched in the vertical direction by a material , and is placed above the first position from the middle position of the upper and lower belt lengths.
The image capturing means, the removing means at a position facing the upper roller member.
An electric device, the first transfer means and the static eliminator
Two transfer means are provided, and are carried by the first image carrying means by the first transfer means.
After transferring the toner image on the surface of the transfer material,
The second image carrier is carried by the second transfer device.
Transfer the toner image on the back surface of the transfer material to remove the static electricity.
The toner image was transferred from the toner image receiver to both sides with a container.
A double-sided image forming apparatus, characterized in that the transfer material is separated . 2. The position of the first transfer means is (1/10 to 10) of the belt length from an intermediate position of the upper and lower belt lengths.
The double-sided image forming apparatus according to claim 1, wherein the double-sided image forming apparatus is 4/10) above. 3. A serial to above the lower roller member to claim 1, characterized in that as the entry position of the transfer material
Double-sided image forming apparatus of the placement. 4. The double-sided image forming apparatus according to claim 3, wherein the cleaning means for the toner image receiving body is provided between the lower roller member and the entry position of the transfer material. 5. The double-sided image forming apparatus according to claim 3, wherein the sheet feeding means for the transfer material is arranged laterally of the toner image receiving body and below the image forming body. .