JP3518250B2 - Transfer device in image forming apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as an electrophotographic copying machine or a laser printer, and more particularly to transferring a toner image in a direction orthogonal to or parallel to a conveying direction of a recording medium such as paper. The present invention relates to a transfer device in an image forming apparatus.

[0002]

2. Description of the Related Art In the field of electrophotographic image forming apparatuses,
For example, as represented by a laser printer, a toner type having excellent resolution and capable of forming a clear image is widely used.

As one of such toner-type image forming apparatuses, the applicant of the present application discloses in Japanese Patent Application No. 7-328600 that the toner image carrier is moved in a direction orthogonal to the conveying direction of the printing paper. We proposed an orthogonal transfer type image forming apparatus that transfers an image. This transfer device rubs a toner image carrier in a direction orthogonal to the conveyance direction of a printing paper and transfers a toner image in small steps, so it is optimal for downsizing of products.

FIG. 3 is a schematic configuration diagram of a transfer device in a conventional image forming apparatus, FIG. 4 is a perspective view showing a transfer process by the transfer device of FIG. 3, and FIG. 5 is a state of displacement of a photosensitive belt during a transfer operation. It is a schematic diagram which shows.

In FIGS. 3, 4 and 5, a photosensitive member roller 1a which is rotationally driven by a motor (not shown) and a photosensitive member belt 1 as an image carrier on the transfer roller 10 are shown in FIGS. It is wound so that it can travel in the direction of arrow A.
The surface of the photoconductor belt 1 is coated with an organic photoconductive material, and the running direction thereof is orthogonal to the paper feed direction of the paper 7 supplied onto the transfer plate 9 by the paper carrying rollers. Then, around the photoconductor belt 1, a charger 2 that uniformly charges the photoconductor belt 1 and an exposure device 6 that irradiates a laser beam 6a to form an electrostatic latent image on the surface of the photoconductor belt 1. Further, a developing roller 3b for supplying toner is built in, and a developing device 3 for pressing the toner 3a against the photosensitive belt 1 to visualize it as a toner image 3c is sequentially arranged. Incidentally, 4 is a cleaning device for removing residual image toner after one transfer, and 5 is a static eliminator for removing residual charge.

Further, at the position facing the transfer plate 9 in the loop of the photoconductor belt 1, a transfer counter roller 8 having an axis perpendicular to the running direction of the photoconductor belt 1 is arranged. The transfer facing roller 8 is connected to a motor (not shown) to apply a constant tension to the photoconductor belt 1 and at the same time, rotates on the surface of the photoconductor belt 1 on the loop side between the paper 7 and the paper. It is possible to travel in a direction orthogonal to the paper feeding direction of No. 7.

The transfer operation of the toner image 3c on the photoconductor belt 1 onto the paper 7 in the conventional transfer device is as follows.

When an image forming operation is instructed by the control unit of the image forming apparatus, the photoconductor roller 1a is rotated by the drive of the motor, and the photoconductor belt 1 starts traveling in the direction of arrow A in FIG. The surface of the photoconductor belt 1 is first charged by the charger 2 according to the content of the image to be formed, and then the charging potential is lowered by the laser beam 6a emitted from the exposure device 6. , An electrostatic latent image is formed.

When the portion of the photosensitive belt 1 on which the electrostatic latent image is formed reaches the developing device 3, the developing roller 3b of the developing device 3 is rotated by its driving means (not shown), and Abut. As a result, while the photoconductor belt 1 moves while being sandwiched between the developing roller 3b and the photoconductor roller 1a, the electrostatic latent image is developed by the toner 3a attached to the surface of the developing roller 3b, and the photoconductor belt 1 A toner image 3c is formed on the top.

When a toner image 3c corresponding to one sheet of paper 7 is formed on the surface of the photosensitive belt 1 by the above operation, the transfer counter roller 8 is driven by the motor to rotate along the paper 7. Move in parallel. During the parallel movement of the transfer counter roller 8, the photoconductor belt 1 is sequentially pressed against the paper 7 by the transfer counter roller 8, and the toner image 3c on the photoconductor belt 1 is transferred onto the paper 7.

In the transfer device capable of such a transfer operation, the transfer counter roller 8 is a kind of transfer roller which moves so as to face the transfer plate 9, and functions as a print head of a thermal transfer printer using an ink ribbon. Fulfill The displacement roller 10 changes its position by following the movement of the transfer opposing roller 8, and is displaced to the left and right in order to eliminate the looseness of the photosensitive belt 1 caused by the movement of the transfer opposing roller 8. . That is, as shown in FIG. 5, the transfer opposing roller 8 is located at the left end C.
When the displacement roller 10 moves from the right end E to the right end D as indicated by the arrow B, the displacement roller 10 moves from the right end E to the left end F.

When the toner image is formed on the photoconductor belt 1, the transfer counter roller 8 is fixed at the position of the left end C, and the photoconductor belt 1 is kept floating in the air as shown by the solid line for this period. By traveling to, the toner image 3c is carried to the side facing the paper 7, as shown in FIG.

The photoconductor belt 1 runs when the transfer counter roller 8 is at the left end C, and the photoconductor belt 1 runs while the transfer counter roller 8 is moving on the sheet 7. It has stopped. However, although the movement of the photoconductor belt 1 and the movement of the transfer counter roller 8 do not occur at the same time as described above, in reality, it is necessary to keep the tension of the photoconductor belt 1 constant. A mechanical connection is maintained between the transfer counter roller 8 and the transfer counter roller 8.

On the other hand, at the time of transfer onto the sheet 7, as shown in FIG. 4, the conveyance of the sheet 7 is temporarily interrupted to make the sheet 7 stand still on the transfer plate 9 and the photosensitive belt 1 runs. Also stop. Then, the portion of the photosensitive belt 1 on which the toner image 3c is formed is rubbed against the paper 7 by rolling the transfer facing roller 8 from the back side, and the photosensitive belt 1 is moved from the left end C to the right end D.
Displace by one step in the direction of. At the same time, a positive voltage is applied to the transfer plate 9 on which the paper 7 is placed, and the negatively charged toner image 3c is attracted from the surface of the photosensitive belt 1 to be peeled off and transferred to the paper 7. After that, when the transfer facing roller 8 located at the right end D is displaced again in the direction of the left end C by one step, one transfer step is completed.

Each time the transfer for one step is completed, the transfer facing roller 8 passes over the paper 7 and moves to the outside of the area of the paper 7, whereby the photosensitive belt 1 is free from the paper 7 on which the transfer has been completed. The paper 7 is conveyed by the effective transfer width of the photosensitive belt 1. After the transfer processing is performed on the entire sheet 7, the processed sheet 7 is sent to the fixing device side, and a new sheet is supplied onto the transfer plate 9.

[0016]

However, in the conventional transfer apparatus as described above, the reference of the side surface of the paper is not on the side of the movement start position of the transfer counter roller 8, so that the transfer counter roller 8 must be completely moved when transferring. It will move in the transfer area.

Therefore, when printing on a small size paper, the transfer facing roller 8 including the part without the paper is
Is moved, the back side of the paper is smeared, and the output paper is deteriorated. Further, since the reference of the side surface of the paper 7 is not on the movement start position side of the transfer facing roller 8, the transfer speed remains the one corresponding to the large size regardless of whether the size of the paper is large or small. Wasted time is also wasted on the transfer of the paper.

An object to be solved in the present invention is to provide a transfer device in an image forming apparatus which does not cause back stain on a sheet after transfer and has a high transfer speed.

[0019]

The present invention is directed to sending a recording medium.
Parallel transfer method in which the transfer opposite roller is arranged parallel to the feed direction
Transfer device, the transfer start position of the transfer facing roller side
Is the reference position before and after the recording medium, and the position
Recording is performed by the transfer counter roller at the determined reference position of the recording medium.
Transfer contact roller to the end of the recording medium
Is configured to reciprocate.

[0020]

With such a structure, the transfer facing roller moves only within a range corresponding to the recording medium sheet positioned at the transfer position and does not move to a portion where there is no sheet. There is no occurrence. Further, when the paper size is small, the moving stroke amount of the transfer facing roller is also small, so the transfer time is also shortened.

[0022]

DETAILED DESCRIPTION OF THE INVENTION The invention according to claim 1 is a toner
Recording a closed-loop photoreceptor belt provided as an image carrier
When it is arranged so that it can run in a direction parallel to the medium feeding direction,
In the loop of the photoconductor belt, the feeding direction of the recording medium
A transfer facing roller that can move in a direction parallel to the
Photosensitive belt by continuous pressing by the image-opposing roller
Parallel transfer method for transferring the toner image carried on the recording medium onto the recording medium
Type transfer device, in which the transfer start position of the transfer opposite roller
Side is the reference position before and after the recording medium, and
The transfer facing roller is recorded at the reference position of the recording medium that has been set.
Contact the recording medium and transfer to the rear edge of this recording medium.
Is the same as in the orthogonal transfer method.
Similarly, even if the paper size is changed,
For small size paper that does not cause back stains
Then, it is said that the time required to move the transfer facing roller should be shortened.
Has a function.

[0023]

[0024]

According to a second aspect of the present invention, the transfer start position of the transfer counter roller is made to face the side facing the fixing device disposed downstream of the transfer device, and the transfer in the final step is completed. After that, the transport distance to the fixing device is shortened, so that the process time for fixing is shortened and the printing speed can be increased.

The embodiments of the present invention will be described below. (Embodiment 1) FIG. 1 is a schematic view showing a transfer process according to a first embodiment of the present invention. In addition, the same members as those described in the prior art are designated by common reference numerals,
Detailed description thereof will be omitted.

First, the difference between the first embodiment and the conventional example is that the reference of the side surface of the sheet 7 is set to the movement start position C side of the transfer facing roller 8, and this movement start position C
A point opposite to the side is a transfer opposite roller stop position detection device 14 arranged so as to reciprocate in the direction of the double arrow in the figure.

Here, the traveling of the photosensitive belt 1 is performed by the paper 7
Control to stop according to the size of. That is, the width detecting means (not shown) for the paper
Is detected, and the moving distance of the photosensitive belt 1 is controlled so as to be changed according to the detected width. And paper 7
The moving distance of the photosensitive belt 1 is determined according to the width of
The photosensitive belt 1 is stopped so that the printed image fits within the width of the paper 7.

When the traveling of the photosensitive belt 1 is stopped, the transfer counter roller 8 moves from the left end C to the conveyance reference position G on the side surface of the paper 7.
Move to. Here, the photosensitive belt 1 whose position fluctuates momentarily by the transfer facing roller 8 is configured to come into contact with the transfer plate 9 for the first time at the transport reference position G,
Here, a positive voltage is applied to the transfer plate 9. Then, the transfer facing roller 8 that is in contact with the paper 7 at the transport reference position G moves to the right end H of the paper 7, and the transfer facing roller 8 that moves to the right end H moves to the left end C in reverse. At this time, the moving distance of the transfer opposing roller 8 to the right end H is determined by the distance detected by the width detecting means of the paper 7, and stops at the right end H. The stop position is determined by the transfer opposite roller stop position detection device 14 moving to the position of the right end H. Here, after the transfer for one step is completed, the paper 7 is conveyed by the effective print width (transfer width for one step).

As described above, by setting the reference at the one end in the width direction of the paper 7 on the side where the transfer of the transfer counter roller 8 is started to the transfer start position C side of the transfer counter roller 8,
Even if the size of the paper 7 changes, the left edge of the paper 7 is always the paper 7
It can be located at the conveyance reference position G on the side surface. Therefore, since the photosensitive belt 1 is pressed from the edge of the paper 7, it does not come into direct contact with the transfer plate 9, toner adhesion to the transfer plate 9 can be prevented, and dirt on the back of the paper 7 is prevented. To be prevented. Further, in the case of a small-sized sheet 7, since the width of the sheet 7 is detected and the transfer facing roller 8 reciprocates by the width of the sheet 7, the moving distance of the transfer facing roller 8 is reduced. It is also possible to increase the printing speed.

In the first embodiment, since the movement start position of the transfer facing roller 8 is the left end, the side surface reference of the paper 7 is the left end. However, when the side surface reference of the paper 7 is the right end. The same effect can be obtained by reversing the configuration of each process around the photosensitive belt 1.

(Embodiment 2) FIG. 2 is a schematic diagram showing a transfer process according to a second embodiment of the present invention. 1 in the figure
Reference numeral 2 is a transfer belt, and 13 is a fixing device.

The transfer device according to the second embodiment is of a parallel transfer type in which the toner image carried on the photosensitive belt 1 is transferred onto the paper in a direction parallel to the conveyance direction of the paper 7, and the front and rear of the paper 7 are transferred. This is different from the conventional example in that the reference, that is, the front end and the rear end of the paper 7 are set to the fixing device 13 side which is the movement start position side of the transfer facing roller.

Further, the parallel transfer system is different from the orthogonal transfer system in the example of FIG. 1 only in that the photosensitive belt 1 is installed in parallel with the conveying direction of the sheet 7, and the sheet 7 is a printing sheet conveying roller 11 Is conveyed to the transfer belt 12. The sheet 7 conveyed to the transfer belt 12 is conveyed to the conveyance reference position K and stopped. Transfer belt 12 here
The length of the transfer area is the same as the length of one sheet of paper 7. When the sheet 7 stops, the toner image forming process similar to the orthogonal transfer method is performed.

That is, when the toner image forming process is completed and the traveling of the photosensitive belt 1 is stopped, the transfer opposing roller 8 moves from the movement start position J to the conveyance reference position K before and after the sheet 7.
Move to. Here, the photosensitive belt 1 whose position fluctuates momentarily by the transfer opposing roller 8 is configured to come into contact with the transfer belt 12 at the transport reference position K for the first time, and a positive voltage is applied to the transfer plate 9 here. Is applied. The transfer counter roller 8 that is in contact with the paper 7 at the transport reference position K moves to the rear end position L of the paper 7, and the transfer counter roller 8 that has moved to the rear end position L moves to the transport reference position K in reverse.

The sheet 7 on which the transfer is completed is fixed to the fixing device 1.
Although the sheet is conveyed to the third sheet and fixed, the conveying speed of the fixing device 13 is set to be slower than the conveying speed of the print sheet conveying roller 11 in order to surely perform the fixing.

As described above, the front and rear of the paper 7 are set to the fixing device 13 side, which is the movement start position side of the transfer counter roller 8, so that the length of the transfer area of the transfer belt 12 is the maximum printable paper. Since the length of the sheet 7 is the same as that of the sheet 7, the sheet 7 is conveyed to the conveyance reference position K even if the length of the sheet 7 becomes short. Therefore, transfer of one sheet of paper 7 can be performed in one operation.

As described above, since the photosensitive belt 1 does not come into direct contact with the transfer belt 12, it is possible to prevent the toner from adhering to the transfer belt 12 and the backside of the paper 7. Further, since the transport speed of the fixing device 13 is set to be slower than the transport speed of the print paper transport roller 11, the transport start position of the transfer counter roller 8 is transported at a slower speed than when the transfer start roller 8 is set to the print paper transport roller 11 side. The shorter the distance is, the faster the printing speed becomes.

In each of the first and second embodiments, it is not always necessary to use a photoconductor as the toner image bearing member, and there is a case where the exposing means is not required.
For example, it is also possible to form an electrostatic latent image by a heat source and develop it to form a toner image, or to blow a toner image carrier which is solidly coated with toner with an air jet to engrave a print image, and to make a toner image. Can be formed.

[0040]

According to the first and second aspects of the present invention, even if the size of the paper is changed, back stains do not occur on these papers, and in the case of small papers, the time required for the transfer facing roller to move. As a result, it is possible to obtain an effect that the printing speed can be improved and the image quality of the formed image can be improved and stabilized.

According to the third and fourth aspects of the present invention, since the conveying distance to the fixing device after the transfer of the last step is completed is shortened, the process time until fixing is shortened, so that the printing speed is increased. Can be achieved.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a transfer process according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing a transfer process according to a second embodiment of the present invention.

FIG. 3 is a schematic configuration diagram of a transfer device in a conventional image forming apparatus.

FIG. 4 is a perspective view showing a transfer process by the transfer device of FIG.

FIG. 5 is a schematic diagram showing a state of displacement of a photosensitive belt during a transfer operation.

[Explanation of symbols]

1 Photoconductor belt (toner image carrier) 1a Photosensitive roller 2 charger 3 developer 3a toner 3b Developing roller 3c toner image 4 Cleaning device 5 Static eliminator 6 Exposure device 7 sheets 8 Transfer counter roller 9 Transfer plate 10 Displacement roller 11 Printing paper transport roller 12 Transfer belt 13 Fixing device 14 Transfer counter roller stop position detector

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masashi Ogawa 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Shinichi Kizu 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. In-house (72) Yusuke Shiihara 1006 Kadoma, Kadoma-shi, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Yukinori Hara, 1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric Industrial Co., Ltd. (56) Reference Documents JP-A-63-249882 (JP, A) JP-A-8-314291 (JP, A) JP-A-6-246960 (JP, A) JP-A-4-69254 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) G03G 15/16

Claims (2)

(57) [Claims] 1. A closed-loop photoconductor belt provided as a toner image carrier is arranged so as to be able to run in a direction parallel to the feeding direction of a recording medium, and in the loop of the photoconductor belt is parallel to the feeding direction of the recording medium. A transfer device of a parallel transfer system in which a transfer opposed roller that is movable in any direction is arranged, and a toner image carried on a photosensitive belt is transferred onto a recording medium by continuous pressing by the transfer opposed roller. The reference position of the front and rear of the recording medium is the starting position side of the recording medium, the transfer counter roller contacts the recording medium at the reference position of the recording medium positioned at this reference position, and the transfer counter roller reciprocates to the rear end of the recording medium. A transfer device in an image forming apparatus that moves. 2. A transfer of the image forming apparatus according to claim 1, characterized by comprising a movement start position of the transfer opposing roller, it is opposite to the side facing the fixing apparatus side positioned downstream of the transfer device device.