JP2003167497A - Double-sided image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a fragment of a sheet of paper from remaining in a fixing unit or any other parts, which is caused when a jammed sheet is torn when the sheet is removed from a fixing part in a double-sided image forming apparatus. <P>SOLUTION: The double-sided image forming apparatus has a first image carrier and the other image carrier that receives thereon a first-side image formed on the first image carrier. The apparatus transfers the first-side image to one side of paper from the other image carrier, and transfers a second-side image formed on the first image carrier onto the other side of the paper, thereby transferring developed images to both the sides of the paper. Thereafter, the apparatus simultaneously fixes the developed images to both the sides. In the both-side image forming apparatus, a means for simultaneously fixing images on both the sides is movable in a direction perpendicular to the direction in which the paper is carried and vertical to the faces of the paper. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for forming images on both sides of a recording medium.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine, a printer or a facsimile, an electrostatic latent image formed on a recording medium (hereinafter also referred to as "paper") is developed with toner,
A type in which this toner image is fixed on a sheet and then discharged to a sheet discharging section is conventionally known and widely used.
In such an image forming apparatus, while the sheet is being conveyed in the apparatus, the leading end of the sheet may hit the proximity member to be caught and jam inside. This is commonly called jam,
As long as the paper is conveyed, such a jam cannot be absolutely avoided. In particular, such a jam easily occurs near the fixing unit.

On the other hand, there is known one configured so that an image can be formed on both sides of a sheet. In the conventional image forming apparatus capable of double-sided recording, the image (visual image) formed on the image carrier is transferred and fixed on a sheet, the sheet is inverted by an inversion path or the like, and the sheet is fed again to be fed. It is a general method to transfer and fix another image (visual image) on the back side.

In the case of double-sided recording by such a system, after the image is fixed on one side, there is no choice but to have a branch path or a reverse path on the downstream side of the fixing means in the sheet conveying direction. For example, in a double-sided copying machine disclosed in Japanese Utility Model Laid-Open No. 5-64174, a conveyance path switching lever is provided between a conveyance roller and a discharge roller on the downstream side of the fixing roller in the sheet conveyance direction, and an intermediate tray unit is further downstream thereof. Is provided.

[0005]

The one in which an image is transferred and fixed on the back surface of the paper after such paper reversal is a paper conveyance because of the paper curl after fixing the one-sided image and the inversion path which must be long. Has a problem in reliability. Furthermore,
When a jam occurs in the fixing device, due to the branch claws and the reversing path existing on the downstream side of the fixing device in the sheet conveying direction, and other device layouts (the upper conveying device and the scanner device),
A direction that is orthogonal to the sheet conveyance direction and is along the plane of the sheet (in the case of the above-mentioned Japanese Utility Model Laid-Open No. 5-64174, FIG.
Can be pulled out only in the direction (perpendicular to the paper surface).

In the jam processing of the fixing device, if the fixing device is moved in the direction orthogonal to the paper conveying direction and along the paper surface, the lateral displacement between the fixing device and the paper discharging device or the transfer conveying device occurs. Due to the relative movement, the jammed paper is torn or a piece of paper remains.

In view of the above-mentioned drawbacks, the present invention solves the above-mentioned drawbacks, and in the fixing unit jam processing in a double-sided image forming apparatus,
An object of the present invention is to prevent the jammed paper from being torn and causing the remaining pieces of paper to be generated in the fixing device or other places.

[0008]

SUMMARY OF THE INVENTION According to the present invention, the above-mentioned problems are solved by a first image carrier and another image carrier to which the first-surface image formed on the first image carrier is transferred ( And a second surface formed on the first image carrier while transferring the first surface image from the other image carrier to one surface of the recording medium. In a double-sided image forming apparatus that transfers a visible image to both sides of a recording medium by transferring the image to the other side of the recording medium, and then simultaneously fixes both sides, a means for simultaneously fixing both sides is provided in the recording medium conveyance direction. This is solved by making it movable in a direction perpendicular to the surface of the recording medium. A substantially horizontal direction can be assumed as a direction orthogonal to the recording medium conveyance direction and perpendicular to the surface of the recording medium.

It is preferable that the means for simultaneously fixing both sides and the discharging means provided on the downstream side of the recording medium conveyance direction, for example, a discharging roller pair, can be moved together. .

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings in a double-sided image forming apparatus adopting a color image forming process with multicolor toner. In the case of a monochrome image forming apparatus, the intermediate transfer belt 10 described below is used.
The present invention can be applied immediately if the photosensitive member is arranged so as to directly contact the final belt image bearing member (third image bearing member in the following embodiments) 100 without the above.

A static eliminator L, a cleaning device 2, a charging device 3 and a developing device 5 are arranged on the outer peripheral portion of the photosensitive member 1 which is a first image bearing member rotatably supported and rotating in the direction of the arrow. A space is provided between the charging device 3 and the developing device 5 for receiving the optical information emitted from the lower exposure device 4. There are four photoconductors 1 (a, b, c, d), but the configuration of the parts arranged around each is the same. Developing device 5
The color of the color material (toner) handled by is different. Photoconductor 1
Is formed by providing an organic semiconductor layer, which is a photoconductive substance, on the surface of an aluminum cylinder having a diameter of about 30 to 100 mm, and a part of the layer is formed on the intermediate transfer belt 10 as the second image carrier. Touching. A belt-shaped photoconductor can also be adopted.

Intermediate transfer belt (also called primary transfer member) 1
0 is a belt having a substrate thickness of 50 to 600 μm and made of a resin film or rubber as a substrate, and has a resistance value that allows the toner to be transferred from the photoconductor 1, and is long in the lateral direction and movable in the arrow direction. The rotating rollers 11, 1
It is supported and stretched by 2 and 13. On the back side (inside of the loop), the first transfer unit 20 is arranged near the photoconductor 1. An intermediate transfer belt cleaning device 25 is disposed outside the belt loop, and wipes off unnecessary toner remaining on the surface after the transfer process is performed on the intermediate transfer belt 10.

The exposure device 4 uses a well-known laser system to irradiate light information corresponding to the color of the toner to be color-separated and developed as a latent image on the surface of the uniformly charged photoreceptor. An exposure device including an LED array and an image forming means can also be adopted.

On the right side of the drawing, a back surface transfer member (also referred to as a secondary transfer member) 100, which is a belt-shaped third image carrier, is vertically arranged. It is conceivable that the arrangement is such that it is tilted diagonally and rises instead of being arranged almost vertically. The back surface transfer member 100 is supported and stretched by rotating rollers 111, 112, 113 so as to be movable in the arrow direction, and the second transfer means 120 is provided on the back side (inside the loop).
Are arranged near the roller 11 that supports the intermediate transfer belt 10. A secondary transfer member cleaning device 250, a charger CH, and the like are arranged outside the belt loop. The cleaning device 250 wipes off unnecessary toner and paper dust remaining on the surface of the secondary transfer body after transferring the toner to the paper.

The transfer unit 120, the roller 113, and the roller 11 supporting the primary transfer member 10 are used to form the primary transfer member 1.
0 and the secondary transfer member 100 contact each other to form a predetermined transfer nip.

The secondary transfer member (transfer member for the back surface) 100 is also a belt having a substrate with a thickness of 50 to 600 μm and a resin film or rubber as a substrate, and has a resistance value that enables transfer of toner from the intermediate transfer belt 10. Have

The recording medium (paper) P is housed in paper feeders (paper cassettes) 26-1 and 26-2 at the bottom of the figure,
The uppermost sheet is conveyed to the registration roller pair 28 via the plurality of guides 29 one by one by the sheet feeding roller 27.

A fixing device 30, a paper ejection guide 31, a paper ejection roller pair 32, and a paper ejection stack section 40 are arranged above the drawing. The fixing device 30 is configured such that a belt having a heating element arranged in a loop is brought into contact with a roller having a heater built in a surface material such as silicone rubber. It is also possible to adopt.

Above the intermediate transfer belt 10, a paper discharge section 40 is provided.
A storage unit TS that can store replenishment toner is provided below the. There are four toner colors, magenta, cyan, yellow, and black, which are in the form of a cartridge TC. A powder pump or the like is appropriately supplied to the developing device of the corresponding color.

A part of the frame 50 of the main body is provided with an opening / closing support shaft 5.
Since the structure is such that it can be rotated and released around 0A, the paper conveyance path is wide open, and it is easy to process jammed paper in this range.

Further, the fixing device 30 and the sheet discharging means (sheet discharging guide, sheet discharging roller pair) are unitized, and as shown by the dotted line, they are integrally drawn out to the right as seen in the figure, and discharged from the fixing section. It is possible to easily handle jammed sheets of paper. An example of the structure for drawing out this portion is as follows.

As shown in FIG. 2, the rails 213 provided on both side plates of the main body of the image forming apparatus are engaged with the rollers 215 provided on the slider 214 provided on the lower side surface of the unit. Also on the lower side of the slider 214,
The arm 218 of the handle lever 217 is rotatably attached around the shaft 219 while being biased clockwise by the torsion spring 220. One end 218a of the arm 218 has a hook shape, and a stopper 221 provided on the rail 213 engages with the hook 218a. Such a configuration is provided on both sides of the unit. The other end of the arm 218 is formed in a cross beam, and a handle 222 is mounted thereon. Therefore, when the handle 222 is lifted up, the arm 21
8, the stopper 221 is disengaged from the distal end portion 218a of the No. 8 slider. Therefore, by pulling the handle 222 to the right in the drawing, the slider 214 moves on the rail 213 via the roller 215, and the entire unit is pulled out in the lateral direction of the device. Be done.

An image forming operation in the image forming apparatus configured as described above will be described. First, the operation when images are obtained on both sides of the paper will be described. When images are to be obtained on both sides of the sheet, the image formed first is called the first side image, and the image formed later is called the second side image, and the sheet side to which the first side image is transferred is the sheet first side ( In terms of expression, it will be referred to as the back surface side, and the paper surface on which the second surface image is transferred will be referred to as the paper second surface (expressed as the front surface side).

The image forming apparatus of this embodiment is a so-called printer, and a signal for writing is sent from a host machine (not shown) such as a PC. The exposure device 4 is driven based on the received image signal, and light from an LD light source (not shown) of the exposure device passes through an optical component (not shown) and is uniformly charged by the charging device 3 to a photosensitive drum. First of all, it reaches the photoconductor indicated by a and forms a latent image corresponding to the writing information (information according to color).

The electrostatic latent image on the photoconductor 1 is developed by the developing device 5, and a toner image is formed and held on the surface of the photoconductor. The toner image on the photoconductor is the first transfer means 2
0 (transfer roller) transfers the image onto the surface of the intermediate transfer belt 10 that moves in synchronization with the photoconductor 1. The surface of the photoconductor 1 is cleaned of the remaining toner by the cleaning device 2 and discharged by the discharging device L to prepare for the next image forming cycle.

The intermediate transfer belt 10 carries the toner image transferred on its surface (the image to be transferred on the first surface of the paper) and runs counterclockwise in the figure. Then, a latent image corresponding to another color is written on the photoconductor 1 indicated by b, and developed with toner of the corresponding color to form a visible image. This visible image is superimposed on the visible image of the previous color already on the intermediate transfer belt 10, and the same processing is performed on the photoconductors 1c and 1d, and finally four colors are superimposed.

At this time, the intermediate transfer belt 10 is moving in the direction of the arrow in synchronization with the photosensitive member 1, and the second transfer means 12
With the action of 0, the image formed on the surface of the intermediate transfer belt 10 is transferred to the surface of the back surface transfer member 100. While the image is formed on the four photoconductors in the so-called tandem format, the intermediate transfer belt (primary transfer member) and the back surface transfer member (secondary transfer member) move, and image formation proceeds. Can be shortened.

When the intermediate transfer belt 10 moves to a predetermined position, the toner image (visual image) to be formed on the other surface of the paper (the second surface of the paper) is re-photographed again in the above-described process.
The image is formed by and the paper feeding is also started. When the paper feed roller 27 rotates counterclockwise, the paper feed cassette 26-
The sheet P at the top of 1 or 26-2 is pulled out and conveyed to the pair of registration rollers 28. During that time, the toner image (first surface image) transferred onto the back surface transfer member 100
Is conveyed to the position where it makes one turn and comes into contact with the intermediate transfer belt 10. The toner image on the surface of the intermediate transfer belt is transferred by the second transfer unit 120 to one side surface (first surface) of the sheet sent between the intermediate transfer belt 10 and the back surface transfer member 100 via the pair of registration rollers 28. It Further, the paper is conveyed upward, and the toner image on the surface of the backside transfer member is
It is transferred to the other surface (second surface) of the paper by the charger CH. At the time of transfer, the sheet is conveyed at a timing so that the position of the image becomes normal.

In this example, the polarity of the toner imaged on the photoconductor 1 is negative. By applying a positive charge to the first transfer unit 20, the toner image formed on the photoconductor is transferred to the intermediate transfer belt 10 (second image carrier). Second
The toner imaged on the intermediate transfer belt 10 is transferred to the transfer member for the back surface (the third
Image carrier 100). Further, the toner on the surface of the intermediate transfer belt is also transferred to the surface on one side of the paper. By applying a positive polarity charge from the charger CH, the negative polarity toner on the surface of the back surface transfer member 100 is attracted and transferred to the other surface of the paper.

The sheet P having the toner images transferred on both sides in the above steps is sent to the fixing device 30, the toner images (both sides) on the sheet are fused and fixed at once, and the pair of discharge rollers 32 passes through the guide pair 31. Thus, the paper is discharged to the paper discharge stack section 40 above the main body frame.

When the paper discharge unit 40 is configured as shown in FIG. 1, the second surface of the double-sided image, that is, the surface (page) transferred from the intermediate transfer belt 10 to the paper becomes the lower surface, and the paper is discharged. Since the sheets are placed on the stack section 40, in order to align the pages, the image of the second page is created first, the toner image is held on the back surface transfer member 100, and the image of the first page is created later. Then, the surface may be directly transferred from the surface of the intermediate transfer belt 10. Therefore, when the sheets are discharged to the discharge stack unit 40 in page order (face-down sheet discharge), the first side image is the second page image and the second side image is the first page image. The same applies to the images on the third and subsequent pages. When there is an image on an even-numbered page, the image on the even-numbered page is first formed and transferred / held on the back surface transfer body 100, and the image before the even-numbered page is transferred. Odd pages are created later and transferred directly from the surface of the intermediate transfer belt 10 to the paper. The image forming order in this case is represented by the number of pages, which is 2 → 1 → 4 → 3 → 6 → 5. Such control of the image forming order is performed by a control unit (not shown) of the image forming apparatus by a known technique of storing image data in a memory.

The image transferred from the intermediate transfer belt 10 to the paper is a normal image on the surface of the photoconductor, and the toner image transferred from the back surface transfer member 100 to the paper is a reverse image (mirror image) on the surface of the photoconductor. To be exposed. Such switching exposure of a normal image and a reverse image (mirror image) can also be realized by a known image processing technique.

After the toner image is transferred from the back surface transfer member 100 to the sheet, a known brush roller, a collecting roller,
A cleaning device 250 equipped with a blade or the like removes unnecessary toner and paper dust remaining on the surface of the back surface transfer member. In the figure, the brush roller is away from the back surface transfer member. This means that the roller can be brought into contact with and separated from the back surface transfer body. Before the transfer to the paper, the backside transfer member is separated while carrying the toner, and comes into contact with the belt transfer member at a stage where cleaning is required. The removed toner is collected in the toner storage area.

Next, the operation for obtaining an image on one side of a sheet will be described. As can be understood from the above description of double-sided image formation, in the case of single-sided image formation, there are two methods, that is, a method of transferring from the back side transfer member to the sheet and a method of transferring from the intermediate transfer belt to the sheet. How to transfer from paper to paper is explained. In this case, the step of transferring toner to the back surface transfer member 100 can be omitted, and the toner image formed on the surface of the photoconductor 1 is transferred to the intermediate transfer belt, and the superimposed image is transferred to the paper P.

In FIG. 1, the paper P is transferred to the intermediate transfer belt 10 and the back surface transfer member 100 in synchronism with each other for alignment with the superimposed image formed on the intermediate transfer belt 10.
Then, the toner image is transferred from the intermediate transfer belt 10 onto the paper (the upper surface of the paper: the surface on the intermediate transfer belt side) by the second transfer unit 120.

The charger CH, which is the third transfer means, does not operate, and the sheet moves together with the back surface transfer member 100 and is sent to the area where the fixing means 30 is present, and the toner is fixed. At this time, after that, the paper is separated from the back surface transfer body 100, is discharged in the direction of arrow A through the guide pair 31 and the paper discharge roller pair 32, and is discharged with the image surface down (face down). It is placed on the stack unit 40. With such a configuration, even if the originals over several pages are processed in order from the first page, the printed matter is in the page order when taken out from the paper discharge stack section 40. The image formation order at this time is 1 →
2 → 3 → 4 → 5 → 6 ...

In the above embodiments, the image formation of a color image using toners of a plurality of colors has been described, but the technical idea of the present invention can be applied to the production of a monochrome image.

[0038]

As described above, according to the image forming apparatus of the present invention, the means for simultaneously fixing both sides is moved in the direction orthogonal to the sheet conveying direction and perpendicular to the sheet surface. Since it is possible, even if the jammed paper extends to the transfer / transport device or the paper discharge device when a jam occurs in the fixing means, even if the fixing means is pulled out during the jam processing,
It is possible to avoid tearing the jammed paper and causing a piece of paper to remain in the fixing device or another place.

By configuring the fixing means and the paper discharging means so that they can be moved together, a member attached downstream of the fixing means in the sheet conveying direction, for example, a jammed paper caught on the fixing separation claw is also used. Move together without breaking,
Can be removed.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a color double-sided printer which is an example of an image forming apparatus to which the present invention is applied.

FIG. 2 is a schematic diagram for explaining a drawing mechanism of a fixing / paper discharging unit.

[Explanation of symbols]

1 photoconductor drum (first image carrier) 3 charging device 4 Exposure equipment 5 Development device 10 Intermediate transfer belt (second image carrier) 20 First Transfer Means 28 Pair of registration rollers 30 fixing device 31 Paper ejection guide 32 Paper ejection roller pair

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2H028 BA06 BA12 BC00                 2H033 AA37 AA46 BA02 BA06 BB00                 2H071 BA14 DA12 DA23 DA24 EA04                 2H072 CA01 EA16 JA02                 3F049 AA04 CA31 DA12 DB04 DB13                       LA03 LA05 LA07 LB03

Claims (3)

[Claims] 1. A first image bearing member, and another image bearing member to which the first surface image formed on the first image bearing member is transferred. By transferring the image from the other image carrier to one surface of the recording medium, and transferring the second surface image formed on the first image carrier to the other surface of the recording medium, both surfaces of the recording medium are transferred. In a double-sided image forming apparatus that transfers a visible image and then fixes it on both sides simultaneously, the means for simultaneously fixing both sides can be moved in a direction perpendicular to the recording medium conveyance direction and perpendicular to the surface of the recording medium. A double-sided image forming apparatus characterized in that 2. The double-sided image forming apparatus according to claim 1, wherein a direction perpendicular to the recording medium conveyance direction and perpendicular to the surface of the recording medium is a horizontal direction. 3. The both sides according to claim 1, wherein the means for simultaneously fixing both sides and the sheet discharging means provided on the downstream side in the recording medium conveying direction are movable together. Image forming apparatus.