JPH05188800A - Image forming device - Google Patents

Abstract

PURPOSE:To precisely obtain the parallelism and to prevent the occurrence of the winkles of a transfer form caused by its twisting and the soiling of an image by providing a frame body rotatively supporting a transfer roller and a center shaft supporting the frame body so as to rock it, and regulating the parallelism of the transfer roller and a resist roller by means of the center shaft and the resist roller abutted thereon. CONSTITUTION:A transfer roller contact/uncontact means has the frame body 15 rotatively supporting the transfer roller 7, the center shaft 18 supporting the frame body 15 so as to rock it against an image forming device main body 6, and a cam 22 rocking the frame body 15. An intermediate member composed of a positioning plate 26 is fixed on the center shaft 18, and the center shaft 18 is abutted on the resist roller 9 via the intermediate member. On the other hand, since the center shaft 18 and the transfer roller 7 are arranged in parallel in advance, as well, the resist roller 9 and the transfer roller 7 are arranged so that both center axis lines are highly accurately in parallel each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image carrier having a toner image on its surface, a transfer roller to which a bias voltage is applied to transfer the toner image on the carrier to a transfer material, and the transfer roller. The present invention relates to an image forming apparatus including a transfer roller contacting / separating unit that contacts and separates a roller with respect to an image carrier, and a registration roller that sends a transfer material between the image carrier and the transfer roller at a predetermined timing.

[0002]

2. Description of the Related Art In an image forming apparatus of the above type configured as an electronic copying machine, a facsimile or a laser printer, a toner image on an image carrier is transferred onto a transfer material by a transfer roller to which a bias voltage is applied. As compared with the case where a corona discharger is used as the transfer device, it has an advantage that the amount of ozone generated can be suppressed (see, for example, JP-A-2-285377).

Further, since the image forming apparatus of this type is provided with the transfer roller contacting / separating means for contacting / separating the transfer roller with respect to the image carrier, the transfer roller is operated at a time other than the time of transferring the toner image. Can be kept away from the image carrier,
Therefore, it is possible to suppress the problem that the residual toner adhering to the image carrier is transferred to the transfer roller and adheres to the transfer material to cause back stain on the transfer material.

Further, as in a color image forming apparatus, a predetermined color image is obtained by superposing toner images of different colors on an image carrier, and the predetermined color image is collectively formed on a transfer material such as plain paper. Even in an image forming apparatus of the type in which the toner image is transferred, the transfer roller can be separated from the image carrier except when the toner image is transferred to the transfer material.
It is possible to prevent the untransferred toner image on the image carrier from being disturbed by the transfer roller.

By the way, the transfer material is fed between the transfer roller and the image carrier at a predetermined timing by the registration roller. At this time, the parallelism between the central axis of the registration roller and the central axis of the transfer roller is high. If it is not good, the transferred transfer material may be wrinkled, and the transfer material may come into contact with the surface of the image carrier before the toner image is transferred, so that the transfer material is contaminated with toner.

In the conventional image forming apparatus of this type,
Since the registration roller and the transfer roller were supported separately without having a special relationship, the parallelism between the central axes of both was likely to be misaligned due to the accumulation of the assembly tolerances of these, and the above-mentioned problems were likely to occur. .. Particularly, when the transfer roller is supported so as to be able to come into contact with and separate from the image carrier, it is difficult to increase the parallelism between the transfer roller and the registration roller as compared with the case where the transfer roller is supported immovably.

[0007]

SUMMARY OF THE INVENTION The present invention has been made on the basis of the above recognition, and an object of the present invention is to provide an image capable of increasing the parallelism between a registration roller and a transfer roller with a very simple structure. It is to provide a forming apparatus.

[0008]

In order to achieve the above object, the present invention provides an image forming apparatus of the type described at the beginning, in which a transfer roller contacting / separating means includes a frame body for rotatably supporting the transfer roller, A transfer roller and a registration roller that have a central shaft that swingably supports the frame body with respect to the image forming apparatus main body, and the central shaft and the registration roller that abuts on the central shaft directly or through an intermediate member. An image forming apparatus is proposed which comprises parallelism regulating means for regulating parallelism with a roller.

The present invention also achieves the same object.
In the image forming apparatus of the type described at the beginning, the transfer roller contacting / separating means includes a frame body that rotatably supports the transfer roller, and a central shaft that swingably supports the frame body with respect to the main body of the image forming apparatus. The frame, and the registration roller abutting against the frame directly or through an intermediate member,
An image forming apparatus is proposed which comprises parallelism regulating means for regulating the parallelism between the transfer roller and the registration roller.

Further, in order to achieve the above object, the present invention provides an image forming apparatus of the type described at the beginning, in which a transfer roller contacting / separating means supports a transfer roller rotatably, and an image of the frame. By a rotatable cam that has a central shaft that swingably supports the forming apparatus main body, and that is attached to the central shaft, and the registration roller that contacts the cam directly or via an intermediate member, An image forming apparatus is proposed which comprises parallelism regulating means for regulating the parallelism between the transfer roller and the registration roller.

In order to achieve the above object, the present invention provides
In the image forming apparatus of the type described at the beginning, the transfer roller contacting / separating means includes a frame body that rotatably supports the transfer roller, and a central shaft that swingably supports the frame body with respect to the main body of the image forming apparatus. A nut fixed to the main body of the image forming apparatus, a feed screw that moves in the axial direction by rotating while screw-engaging the nut, and abutting on the feed screw directly or via an intermediate member. An image forming apparatus is proposed in which parallelism regulating means for regulating the parallelism between the transfer roller and the registration roller is constituted by the central shaft that is movable according to the movement of the feed screw.

[0012]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a partial view of a color image forming apparatus which is an example of the image forming apparatus. Reference numeral 1 denotes a drum-shaped photosensitive member, which is rotationally driven in the direction of the arrow shown. Code 2
Represents an intermediate transfer belt, which is wound around a driving roller 3, a bias roller 4, and a driven roller 5, and is driven at a constant speed with the photoconductor 1 in the direction of the arrow in the figure. Bias roller 4
The portion of the intermediate transfer belt wound around is in contact with the photoconductor 1.

A toner image of the first color, for example, a yellow toner image is formed on the surface of the photoconductor 1 by a charging device, an exposing device and a developing device which are not shown. This toner image is transferred to the intermediate transfer belt 2 under the action of the bias voltage applied to the bias roller 4, and the residual toner adhering to the surface of the photoconductor after the transfer of the toner image is a cleaning device (not shown). Are removed from the surface of the photoconductor.

Then, in the same manner as described above, a toner image of, for example, magenta color is formed on the photoconductor 1, and this toner image is superposed on the yellow toner image already transferred onto the intermediate transfer belt 2. Transcribed. In the same manner, a cyan toner image and a black toner image are sequentially formed on the photoconductor 1, and these are sequentially transferred onto the intermediate transfer belt 2 so as to be superimposed on the already transferred toner image. In this way, a full-color toner image is formed on the intermediate transfer belt 2.

The intermediate transfer belt 2 carries the toner image as described above, and constitutes an example of the constitution of the image carrier.

The full-color toner image carried on the intermediate transfer belt 2 is applied to the transfer roller 7 on the transfer material 8 passing between the transfer roller 7 rotating counterclockwise and the intermediate transfer belt 2. And is transferred under the action of a bias voltage for transferring the toner image. That is, the toner image on the intermediate transfer belt 2 is electrostatically transferred onto the transfer material 8 by the electric field formed by the bias voltage applied to the transfer roller 7. The transfer material 8 is made of plain paper, for example. Hereinafter, such transfer material will be referred to as transfer paper.

The transfer sheet 8 is fed at a predetermined timing between the transfer roller 7 and the intermediate transfer belt 2, which are in contact with each other, as the pair of registration rollers 9 and 9a shown in FIG. The toner image is transferred to a predetermined area of the paper 8. The pair of registration rollers 9 and 9a are arranged parallel to each other and rotate while making rolling contact with each other.

The transfer paper 8 that has passed between the intermediate transfer roller 2 and the transfer roller 7 passes through a fixing device (not shown), and at this time, the toner image on the transfer paper 8 is fixed on the transfer paper 8.

On the other hand, the toner remaining on the intermediate transfer belt after the toner image is transferred is removed from the intermediate transfer belt 2 by the cleaning member including the cleaning brush roller 11 and the cleaning blade 12 of the cleaning device 10 shown in FIG. To be removed.

Such cleaning members 11 and 12
Is always contacted with the intermediate transfer belt 2, the toner image on the intermediate transfer belt 2 before being transferred to the transfer paper 8 will be damaged. Therefore, for example, the cleaning device 1
0 is swingably supported around its pivot 13,
Until the transfer of the toner image onto the transfer paper 8 is completed, the cleaning device 10 is held at a position separated from the intermediate transfer belt 2 as shown in FIG. 1, and the cleaning members 11 and 12 are separated from the intermediate transfer belt 2. deep.

When the transfer of the toner image onto the transfer paper 8 is completed, the cleaning device 10 is rotated clockwise in FIG. 1 and the cleaning members 11 and 12 are brought into contact with the intermediate transfer belt 2 to bring the belt 2 into contact therewith. Remove the residual toner on top. After completing the cleaning operation, the cleaning members 11 and 12 are separated from the intermediate transfer belt 2.

For the same reason, the transfer roller 7 is separated from the intermediate transfer belt 2 except when the toner image is transferred from the intermediate transfer belt 2 to the transfer paper 8, and the toner on the belt 2 is disturbed. Is being blocked. For this purpose
A transfer roller contacting / separating unit for contacting / separating the transfer roller 7 with respect to the intermediate transfer belt 2 is provided, and its specific configuration is as follows.

As shown in FIGS. 2 and 3, on the front side and the back side of the image forming apparatus main body 6, a front side plate 14 and a rear side plate 14a constituting a support frame of the main body 6 are arranged in parallel with each other. ing.

On the other hand, the front and rear shafts of the transfer roller 7 are rotatably fitted to the front and rear side plates of the frame body 15 through long holes 16 and 16a formed in the vertical direction through bearing members. Compression coil springs 17, 1 mounted in the long holes 16, 16a
It is biased upward by 7a.

A central shaft 18 is attached to the frame body 15. In the illustrated example, the central shaft 18 and the transfer roller 7 extend parallel to each other. The rear end of the central shaft 18 is
The front end of the central shaft 18 is fitted into a reference hole 19 formed in the rear plate 14a, and a support hole 21 formed in a front small plate 20 detachably fixed to the front plate 14 is formed. Mated. The front small side plate 20 is also an element forming a part of the image forming apparatus main body 6.

The frame body 15 may be fixedly fixed to the central shaft 18 or may be rotatably supported. However, when the frame body 15 is fixed immovably, the central shaft 18 and the front side small plate 14a. The side plate 20 is rotatably supported. In short, the frame body 15 may be supported on the image forming apparatus main body 6 so as to be swingable around the central axis of the central axis 18. Therefore, when the frame 15 is swingably supported by the central shaft 18, the central shaft 18 may be non-rotatably supported by the side plates 14a and 20 or may be rotatably supported.

On the other hand, each shaft end of a cam 22 is rotatably supported by the front plate 14 and the rear plate 14a, and the cam surface of the cam 22 is in contact with the tip of the frame 15. This cam 2
The frame 15 is oscillated around the central axis of the central shaft 18 by rotationally driving 2 by a driving device (not shown), which causes the transfer roller 7 to move.
Can be brought into and out of contact with. That is, when the full-color toner images on the intermediate transfer belt 2 are collectively transferred to the transfer paper 8, the transfer roller 7 is brought into contact with the intermediate transfer belt 2 and a bias voltage is applied to the roller 7, When the toner image on the photoconductor 1 is being transferred onto the transfer belt 2, the transfer roller 7 is separated from the intermediate transfer belt 2.

FIG. 4 shows the transfer roller 7 separated from the intermediate transfer belt 2, and FIG.
1 schematically shows a state in which the intermediate transfer belt 2 is in contact with the intermediate transfer belt 2 via Y, M, and C in these drawings represent yellow toner, magenta toner, and cyan toner, respectively. Reference numeral 25 indicates a power supply that applies a bias voltage to the transfer roller 7.

As described above, the transfer roller contacting / separating means in this example is the frame 15 for rotatably supporting the transfer roller 7.
A central shaft 18 for swingably supporting the frame body 15 with respect to the image forming apparatus main body 6, and a cam 2 for swinging the frame body 15.
However, a drive device such as a solenoid may be used instead of the cam 22.

Further, the transfer roller 7 and the frame body 15 constitute a transfer unit for transferring the toner image on the intermediate transfer belt 2 onto the transfer paper 8, and the frame body 15 of the unit, as shown in FIG. The base end portion of the cleaning blade 23 whose front end is pressed against the peripheral surface of the transfer roller 7 is fixed. The blade 23 is used to scrape foreign matter such as paper dust attached to the transfer roller 7, and the scraped foreign matter falls into a collection case 23a that is detachably supported by the frame 15 and is stored therein. To be done.

By detaching the front small side plate 20 from the front side plate 14 as shown in FIG. 3, the above-mentioned transfer unit is pulled out to the front side of the image forming apparatus together with its central axis 18, and maintenance work for the unit is performed. You can do it. A notch 24 is formed in the front side plate 14 so that the transfer unit can be attached and detached.

By the way, as described above, the transfer paper 8 is brought into contact with the intermediate transfer belt 2 and the transfer roller 7 by the pair of registration rollers 9 and 9a arranged in parallel with each other.
The registration roller and the transfer roller 7 are preferably arranged in parallel with each other with high accuracy at this time.

As shown in FIGS. 9 and 10, when the central axis of the transfer roller 7 is Ct and the central axis of the lower registration roller 9 is Cr, the parallelism between the two axial axes Ct and Cr is deviated. When the toner image is transferred onto the transfer paper 8 in this state, the slack of the transfer paper 8 is deviated due to the deviation of the transfer paper 8 in the traveling direction as shown in FIG. Wrinkles may occur, or the transfer paper 8 may come into contact with the surface of the intermediate transfer belt before transfer, and the transfer paper 8 may be contaminated with toner. In the conventional image forming apparatus in which the transfer roller is supported so as to be able to come into contact with and separate from the intermediate transfer belt, due to the small play of the transfer roller support portion and the slight play of the support member supporting the transfer roller, The parallelism between the transfer roller and the registration roller was easy to shift.

Therefore, in the illustrated image forming apparatus, the transfer roller 7 is positioned with reference to the registration roller 9 so that the parallelism between them can be obtained with high accuracy. Make it clear.

First, as shown in FIGS. 2 and 3, a cylindrical or disk-shaped positioning plate 26 is concentrically fixed to the central shaft 18 at the front side of the central shaft 18. There is. The positioning plate 26 may be rotatably supported by the central shaft 18.

On the other hand, the shafts of the upper and lower registration rollers 9 and 9a are rotatably supported by the front side plate 14 and the rear side plate 14a, respectively, and their positions are set in advance correctly.

At this time, the hole 27 of the rear plate 14a that supports the shaft portion on the back side of the lower registration roller 9 and the reference hole 19 of the rear plate 14a that supports the end portion on the back side of the central shaft 18 described above.
As shown in FIG. 3, the center-to-center distance between and is L, and the radius of the positioning plate 26 and the front side shaft portion 2 of the registration roller 9 are
When the radii of 8 are Da and Db respectively as shown in FIG. 2, the respective sizes are set so as to satisfy L = Da + Db. The reference hole 19 and the hole 27 that supports the shaft portion on the back side of the registration roller 9 are formed in the same rear side plate 14a, and their positions are set with high accuracy.

As shown in FIG. 3, the front small side plate 20 is provided with the support hole 21 for supporting the front end of the central shaft 18 as described above. A hole 29 into which the shaft portion 28 on the front side is fitted with substantially no play and an elongated hole 30 are formed.
9 and 30 are located on the same plane, which is a horizontal plane in this example, and the long hole 30 is formed long along this plane.

Further, a screw hole 32 is formed in the front side plate 14, and the screw hole 32 is in the horizontal plane described above with reference to the hole 31 of the front side plate 14 which supports the front side shaft portion 28 of the registration roller 9. It is located in. In the long hole 30 formed in the front small side plate 20 and the screw hole 32, a screw 33 is screwed and tightened, and another screw hole 34 formed in the front side plate 14 and the front small side plate 20. Another screw 36 is screwed into the formed hole 35 and is tightened to fix the front small side plate 20 to the front side plate 14.

The support hole 21 formed in the front small side plate 20 into which the central shaft 18 is fitted is also elongated in the horizontal plane direction, and a pressure member composed of a compression coil spring 37 is arranged in this support hole 21. Has been done.

To attach the front small side plate 20 to the front side plate 14, before the screws 33 and 36 are screwed, the hole 29 of the front small side plate 20 is fitted to the shaft portion 28 of the registration roller 9 and the central shaft is attached. The front end of 18 is fitted into the support hole 21, and then the front small side plate 20 is fixed to the front side plate 14 by screws 33 and 36. At this time, the shaft portion of the registration roller 9 which has occupied a predetermined position in advance. Since 28 fits into hole 29, front small side plate 20 is properly positioned and attached to front side plate 14.

When the front small side plate 20 is fixed to the front side plate 14 in this way, the front end of the central shaft 18 is provided with the support hole 21.
The compression coil spring 37 mounted on the urging member urges the registration roller 26 toward the registration roller 9 in the horizontal plane described above.
Press against # 8. At this time, the shaft portion 28 of the registration roller 9
Since the radius Db of the positioning plate 26 and the radius Da of the positioning plate 26 have the relationship of L = Da + Db as described above, the center-to-center distance between the registration roller 9 and the central shaft 18 is L even on the front side thereof. It becomes the size of. Registration roller 9 on the back side
Since the center-to-center distance between the center axis 18 and the center axis 18 is also set to L in advance, the two are positioned in parallel with each other.

On the other hand, since the central shaft 18 and the transfer roller 7 are also preliminarily arranged in parallel with each other, after all, the registration roller 9
The central axes of the transfer roller 7 and the transfer roller 7 are arranged in parallel with each other with high accuracy. In this way, the transfer roller 7 can be positioned with the registration roller 9 as a reference, and both can be arranged in parallel with each other. Therefore, as shown in FIG. 10, it is possible to prevent the transfer paper 8 from being wrinkled and the transfer paper 8 from being contaminated with toner.

In the above embodiment, the intermediate member composed of the positioning plate 26 is fixed to the central shaft 18, and the central shaft 18 and the registration roller 9 are brought into contact with each other via the intermediate member. It may be brought into contact with the registration roller 9, or conversely, another intermediate member such as a bearing may be attached to the shaft portion 28 of the registration roller 9, and the central shaft 18 may be directly attached to this or an intermediate member such as the positioning plate 26. You may make it contact via.

As described above, in the present embodiment, the parallelism regulation for regulating the parallelism between the transfer roller 7 and the registration roller 9 by the central shaft 18 and the registration roller 9 which comes into contact with the central shaft 18 directly or through the intermediate member. Means are configured.

In the second embodiment shown in FIG. 6, in FIG.
The positioning plate 26 shown in FIG. 2 is not provided, and instead, the front side portion 38 of the frame body 15 is brought into contact with the shaft portion 28 of the registration roller 9 (both refer to FIG. 2) to transfer the roller 9 and the transfer roller 9. It is configured to obtain parallelism with the roller 7. That is, the peripheral portion of the front side portion 38 of the frame body 15 has a radius R = D with respect to the center of the hole of the frame body 15 into which the central shaft 18 is fitted.
It is formed in an arc shape of a, and this peripheral portion is formed by the registration roller 9
It is brought into contact with the shaft portion 28 of the. Also in the second embodiment, the radius of the shaft portion 28 of the registration roller 9 is Db.
(FIG. 2), the distance between the central axes of the center shaft 18 and the registration roller 9 is set to L = Da + Db on both the front side and the back side, whereby the transfer roller 7 and the registration roller 9 are parallel to each other. Positioned. Other configurations are the first
There is no difference from the example. Also in this case, the portion 38 of the frame body 15 can be brought into contact with the registration roller 9 via an intermediate member (not shown).

In the second embodiment, the parallelism regulating means for regulating the parallelism between the transfer roller 7 and the registration roller 9 by the frame body 15 and the registration roller 9 which comes into contact with the frame body 15 directly or via an intermediate member. According to this configuration, the positioning plate 26 in the first embodiment can be omitted, and the number of parts can be reduced.

FIG. 7 is a front view showing a third embodiment.
In this embodiment, the hole 29a of the front small side plate 20 into which the shaft portion 28 of the registration roller 9 is fitted is, for example, a long hole formed in a horizontal plane, and the front side plate 14 is rotatable without any positional movement. The front small side plate 20 is horizontally movable with respect to the shaft portion 28 supported by. This long hole 29a
A compression coil spring 40, which is an example of a pressing member that biases the front small side plate 20 to the right in FIG. Further, a positioning plate fixed to the front side portion of the central shaft 18 is formed as a disc-shaped eccentric cam 26a, and further, a front small side plate 20 to which the end of the central shaft 18 is fitted.
The hole 21a is not a long hole but a hole 21a into which the end is rotatably fitted without substantially rattling. The cam 26a and the shaft portion 28 of the registration roller 9 can be pressed against each other by the spring 40 described above. The compression coil spring 37 and the positioning plate 26 shown in FIG. 2 are not provided, and other configurations are the same as those of the first embodiment.

In the third embodiment, the screws 33,
Before the front small side plate 20 is fixed to the front side plate 14 by 36, for example, the tip of a driver (not shown) is engaged with the groove 39 formed on the front side end surface of the center shaft 18, and the center shaft 1
Rotate 8. As a result, the cam 26a also rotates, and the front small side plate 20 also moves left and right. On the other hand, since the registration roller 9 against which the cam 26a is pressed by the action of the spring 40 does not move, the distance L1 between the central axis of the roller 9 and the central axis of the central axis 18 changes, which causes the registration The parallelism between the central axes of the roller 9 and the transfer roller 7 can be finely adjusted to position them in parallel with each other. After the adjustment work is completed, the screws 33 and 36 are tightened to fix the front small side plate 20 to the front side plate 14. Also the central axis 1
8 and the cam 26a are also preferably fixed to the front small side plate 20. For example, a screw is formed on the front end of the central shaft 18, and a nut (not shown) is screwed into the screw and tightened. The central shaft 18 can be fixed to the small side plate 20. In this case, the frame body 15 is swingably supported with respect to the central shaft 18.

Of course, also in this embodiment, the cam 26a
May be brought into contact with the registration roller 9 via an intermediate member (not shown).

The cam 26a is rotatably supported by the central shaft 18, and the cam 26a is carried out in the same manner as described above.
It is also possible to rotate a and adjust the position of the central shaft 18 with respect to the registration roller 9 that is in pressure contact with this so as to adjust the parallelism between the registration roller 9 and the transfer roller 7.

As described above, in the third embodiment, the transfer roller is constituted by the rotatable cam 26a attached to the central shaft 18 and the registration roller 9 which comes into contact with the cam 26a directly or via an intermediate member. A parallelism regulating means for regulating the parallelism between 7 and the registration roller 9 is constituted.

FIG. 8 is a front view showing a fourth embodiment,
In this example, the positioning plate 26 shown in FIG. 2 is also the front small side plate 2.
0 is also not provided, and instead, the front end of the central shaft 18 that supports the frame 15 is fitted into a long hole-shaped support hole 21b formed in the front side plate 14 and is horizontally moved. It is movable. The registration roller 9 is rotatably supported by the front side plate 14 in the same manner as in the first embodiment.

A pressure member composed of a compression coil spring 37a is mounted in the support hole 21b, and the central shaft 18 is biased in a direction away from the registration roller 9 by this.

A nut 41 is fixedly arranged on the front plate 14 which constitutes a part of the image forming apparatus main body 6, and the nut 4
A feed screw 42 is screw-engaged with 1, and one end of the feed screw 42 is pressed against the end of the central shaft 18 directly or via an intermediate member (not shown). A knob 43 is formed on the other end of the feed screw 42. Other configurations are the same as those of the first embodiment shown in FIGS. 2 and 3.

In order to adjust the parallelism between the transfer roller 7 and the registration roller 9, the knob 43 is rotated and the feed screw 42 screw-engaged with the nut 41 is rotated to move it in the axial direction. As a result, the front end of the central shaft 18 moves in the direction toward or away from the registration roller 9 together with the front side of the frame body 15, thereby positioning the transfer roller 7 and the registration roller 9 in parallel. be able to.

In the fourth embodiment shown in FIG. 8, the parallelism regulating means for regulating the parallelism between the transfer roller and the registration roller is a nut 4 fixed to the image forming apparatus main body 6.
1 and the feed screw 42 that moves in the axial direction by rotating while screw-engaging the nut 41, and abuts on the feed screw 42 directly or via an intermediate member.
However, the configuration of this embodiment can be applied to an image forming apparatus having a front small side plate.

In the image forming apparatus shown in FIG. 1, the toner image formed on the photoconductor 1 is temporarily transferred to the intermediate transfer belt 2 and then the toner image is transferred to the transfer paper 8. However, for example, the present invention can be applied to an image forming apparatus of a type in which a toner image formed on a latent image carrier is directly transferred from a photoconductor to a transfer material. In this case, the latent image carrier is An image carrier that carries a toner image is configured. The present invention can also be applied to an image forming apparatus that is not a color type.

[0060]

In the image forming apparatus according to the first and third aspects of the present invention, since the central axis of the frame body that rotatably supports the transfer roller is positioned with respect to the registration roller, the central axis of the registration roller and the transfer are transferred. The parallelism of the central axis of the roller can be obtained with high accuracy, and when the transfer material is passed from the registration roller to the transfer roller, it is possible to prevent wrinkles and image stains due to twisting on the transfer paper, and obtain a high quality image. be able to.

In the image forming apparatus according to the second aspect of the present invention, since the frame body also functions as the positioning plate, the above effects can be obtained with a small number of parts.

In the image forming apparatus according to the fourth aspect, it is possible to sufficiently absorb the error due to the assembly tolerance and further improve the accuracy of the parallelism between the transfer roller and the registration roller by the rotation of the feed screw.

[Brief description of drawings]

FIG. 1 is a schematic view showing a part of a color image forming apparatus.

FIG. 2 is a front view showing details of a transfer roller and a configuration related thereto.

FIG. 3 is a perspective view illustrating a part of FIG. 2 with some elements omitted.

FIG. 4 is an explanatory diagram showing a state in which a transfer roller is separated from an intermediate transfer belt.

FIG. 5 is an explanatory diagram showing a state in which a transfer roller is in contact with an intermediate transfer belt.

FIG. 6 is a partial front view showing a second embodiment.

FIG. 7 is a front view showing a third embodiment.

FIG. 8 is a front view showing a fourth embodiment.

FIG. 9 is a plan view illustrating a parallel state of a registration roller and a transfer roller.

FIG. 10 is a perspective view illustrating a problem when the parallelism between the registration roller and the transfer roller becomes poor.

[Explanation of symbols]

 7 Transfer Roller 8 Transfer Material 9 Registration Roller 9a Registration Roller 15 Frame 18 Center Shaft 26a Cam 41 Nut 42 Feed Screw

Claims (4)

[Claims] 1. An image bearing member carrying a toner image on a surface thereof,
A transfer roller to which a bias voltage is applied to transfer the toner image on the carrier to a transfer material, a transfer roller contacting / separating unit for contacting / separating the transfer roller to / from the image carrier, and the image carrier In an image forming apparatus including a registration roller that feeds a transfer material between the roller and the roller at a predetermined timing, the transfer roller contacting / separating unit forms a frame that rotatably supports the transfer roller, and forms an image on the frame. A parallelism between the transfer roller and the registration roller is provided by having a central shaft swingably supported with respect to the apparatus main body, and the central shaft and the registration roller abutting against the central shaft directly or through an intermediate member. An image forming apparatus comprising a parallelism restricting means for restricting the temperature. 2. An image carrier having a toner image on its surface,
A transfer roller to which a bias voltage is applied to transfer the toner image on the carrier to a transfer material, a transfer roller contacting / separating unit for contacting / separating the transfer roller with respect to the image carrier, and the image carrier In an image forming apparatus including a registration roller that feeds a transfer material between the roller and the roller at a predetermined timing, the transfer roller contacting / separating unit forms a frame body that rotatably supports the transfer roller, and an image forming the frame body. A parallelism between the transfer roller and the registration roller, which has a central shaft swingably supported with respect to the apparatus main body, and is formed by the frame body and the registration roller that abuts on the frame body directly or through an intermediate member. An image forming apparatus comprising a parallelism restricting means for restricting the temperature. 3. An image bearing member carrying a toner image on its surface,
A transfer roller to which a bias voltage is applied to transfer the toner image on the carrier to a transfer material, a transfer roller contacting / separating unit for contacting / separating the transfer roller with respect to the image carrier, and the image carrier In an image forming apparatus including a registration roller that feeds a transfer material between the roller and the roller at a predetermined timing, the transfer roller contacting / separating unit forms a frame that rotatably supports the transfer roller, and forms an image on the frame. A rotatable cam attached to the central shaft and a registration roller that abuts the cam directly or via an intermediate member. An image forming apparatus comprising a parallelism regulating means for regulating the parallelism between a transfer roller and a registration roller. 4. An image carrier having a toner image on its surface,
A transfer roller to which a bias voltage is applied to transfer the toner image on the carrier to a transfer material, a transfer roller contacting / separating unit for contacting / separating the transfer roller with respect to the image carrier, and the image carrier In an image forming apparatus including a registration roller that feeds a transfer material between the roller and the roller at a predetermined timing, the transfer roller contacting / separating unit forms a frame body that rotatably supports the transfer roller, and an image forming the frame body. A nut fixed to the image forming apparatus main body, which has a central shaft swingably supported with respect to the apparatus main body, and a feed screw that moves in the axial direction of the nut by rotating while engaging with the nut. A parallelism regulating means for abutting the feed screw directly or via an intermediate member and regulating the parallelism between the transfer roller and the registration roller by the central shaft movable according to the movement of the feed screw. An image forming apparatus characterized in that.