JP3368699B2 - 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 an image forming apparatus such as a copying machine or a laser beam printer using an electrophotographic system, and an image carrier on which a toner image is formed and a material to which the toner image is transferred. The present invention relates to an image forming apparatus that includes a transfer material carrier that is rotated and carries a transfer material for transfer to and from which the transfer material carrier is provided so as to be capable of contacting and separating from the image carrier.

[0002]

2. Description of the Related Art Conventionally, as one of image forming apparatuses,
An electrostatic latent image, which is developed with toners of different colors, is formed on the image carrier, toners of corresponding colors are supplied to each electrostatic latent image to develop, and this electrostatic latent image is formed. 2. Description of the Related Art A full-color electrophotographic copying machine is known in which toner images of respective colors are sequentially superposed and transferred onto a transfer material carried on a transfer material carrier.

An example of an image bearing member and a transferred material bearing member in such a full-color electrophotographic copying machine is shown in FIG. 7 which is a plan view and FIG. 7 which is a sectional view taken along line VII-VII in FIG. The illustrated image carrier 1 is composed of a photosensitive drum rotatably supported by a shaft 1a.
A laser beam carrying image information is irradiated to form an electrostatic latent image, and toner is supplied to the electrostatic latent image to form a toner image on the surface. Further, the transferred material carrying member 2 has a shaft 2a.
The transfer drum 2 is rotatably supported by the transfer drum 2. The transfer drum 2 adsorbs a transfer material (not shown) and presses the transfer material on the photosensitive drum 1 to transfer the toner image to the transfer material. .

When performing full-color copying, for example, the image information is black (K) image information, yellow (Y) image information,
A laser beam carrying K image information is decomposed into magenta (M) image information and cyan (C) image information to form an electrostatic latent image on the photosensitive drum 1, and K toner is supplied to this to form K toner. An image is formed, and this K toner image is transferred to the transfer drum 2.
Then, a Y electrostatic latent image is formed on the photosensitive drum 1 with a laser beam carrying Y image information, and Y toner is supplied to this to form a Y toner image. Then
This Y toner image is superposed and transferred onto the K toner image of the transferred material which has been rotated once by the transfer drum 2, and the M toner image and the C toner image are sequentially transferred and superposed onto the transferred material by the same process. Then, full-color copying is performed.

In the above-described full-color electrophotographic copying machine, conventionally, the transfer drum 2 is constructed so as to be able to come into contact with and separate from the photosensitive drum 1 whose arrangement position is fixed. When the material to be transferred is clogged between the transfer material and the transfer material 2, the transfer drum 2 is separated from the photosensitive drum 1 to facilitate the removal of the material to be transferred. More specifically, as shown in the drawing, a shaft 4 is bridged between the front and rear frames 3a and 3b,
Front and rear support plates 5a and 5b are rotatably provided at predetermined intervals, and the front and rear support plates 5a and 5b support the shaft 2a of the transfer drum 2.
About the center of the transfer drum 2 is rotatable in the direction of the arrow A, and the rotation allows the transfer drum 2 to come into contact with and separate from the photosensitive drum 1.

By the way, in the full-color electrophotographic copying machine as shown in the figure, since the toner images of the respective colors are sequentially superposed and transferred as described above, the photosensitive drum 1 of the transfer drum 2 is rotated between each rotation of the transfer drum 2. When a positional deviation occurs in the axial direction with respect to, a positional deviation occurs between the toner images of the respective colors that are superimposed and transferred, and a phenomenon called color deviation occurs. Therefore, in order to prevent this, the relative position in the axial direction of the transfer drum 2 with respect to the photosensitive drum 1 must always be constant.

Therefore, as described above, the front and rear support plates 5 are
In the case where the transfer drum 2 is supported by the photosensitive drum 1 via a and 5b so as to be able to come into contact with and separate from the photosensitive drum 1, there is looseness between the shaft 4 and the front and rear support plates 5a and 5b and the front and rear support plates 5a. ，
There is a problem that axial displacement of the transfer drum 2 is likely to occur due to deformation of 5b and the like. Therefore, conventionally, as shown in the figure, the reinforcing member 6 is provided between the front and rear support plates 5a and 5b.
And the thickness of the front support plate 5a is increased to suppress the deformation of the support plate 5a and reduce the play between the support plate 5a and the shaft 4, whereby the axial direction of the transfer drum 2 is reduced. The position shift of is suppressed.

[0008]

However, the contact pressure between the photosensitive drum 1 and the transfer drum 2 is almost constant over the entire axial direction, along with the demand for suppressing the axial displacement as described above. Is required. However, the reinforcing member 6 and the support plate 5a are provided as described above.
If the rigidity of the supporting member 7 (the supporting plates 5a, 5b in the illustrated conventional example) of the transfer drum is increased by increasing the thickness of the transfer drum 2, the transfer drum 2 is not supported when the shafts 1a, 2a of the both drums are not completely parallel. It becomes difficult for the support member 7 to be deformed so that the shaft 2a of the transfer drum becomes parallel to the shaft 1a of the photoconductor drum when it is pressed against the photoconductor drum 1. There is a problem that it is difficult to make the contact pressure of both drums 1 and 2 constant over the entire contact range in the axial direction because the contact pressure remains unparallel to the axis 1a.

In view of the above circumstances, an object of the present invention is to prevent axial displacement of the transfer material carrier with respect to the image carrier, and to make their contact pressure uniform over the entire axial contact range. An object is to provide an image forming apparatus capable of achieving the above.

[0010]

In order to achieve the above object, an image forming apparatus according to the present invention includes an image carrier on which an electrostatic latent image is formed and toner is supplied to develop the electrostatic latent image. A transfer-target-material-carrying member which is provided so as to support and rotate the transfer-target material so as to transfer the toner image formed by the development to the transfer-target material, and to be brought into contact with and separated from the image carrier. The image forming apparatus is provided with a pressing unit that elastically presses the transfer material carrier from the outside in the rotation center axis direction of the transfer material support body to regulate the position of the transfer material support body in the rotation center axis direction. It is characterized by

[0011] Here, in the image forming apparatus, the pressing means, the transfer material carrying member at the inner side than the outer periphery of the rotary shaft components of the object scene material carrying member, rotation of the transfer material carrying member It is elastically pressed from the outside in the axial direction . Further, in the image forming apparatus, the pressing means is provided only on one side in the rotation center axis direction of the transferred material carrying body, and is different from the one side in the rotational axis direction of the transferred material carrying body. A pressing force supporting member that supports the pressing force of the pressing means from the outside may be provided on one side.

Further, in the above-mentioned image forming apparatus, the pressing means may have a rotating body at the tip of the pressing means in the pressing direction, the rotating body rotating when the transfer-targeted material carrier is brought into contact with or separated from the image carrier. preferable. Further, in the above image forming apparatus, when the pressing force supporting member is provided, the pressing force supporting member rotates at a position in contact with the transfer material carrying member when the transfer material carrying member comes into contact with or separates from the image carrying member. It preferably comprises a rotating body.

[0013]

As described above, the image forming apparatus according to the present invention elastically presses the transfer material carrier from the outer side in the axial direction of the rotation center axis of the transfer material carrier to rotate the center of rotation of the transfer material carrier. Since the pressing means for restricting the position in the axial direction is provided, the position of the transfer target material carrier is restricted by the pressing means, and the position of the transfer target material support member in the axial direction with respect to the image carrier is controlled. The positional shift is suppressed, and the color shift can be prevented.

Further, by the pressing means, the transfer material carrying member is pressed in the region of the transfer material carrying member inside the outer periphery of the rotary shaft constituting member, so that the moment applied to the transfer material carrying member is kept low. Therefore, it is possible to prevent the transfer-target material carrier and the supporting member of the transfer-target material carrier from being deformed by the moment, and to prevent the contact pressure between the transfer-target material carrier and the image carrier from being varied.

Further, since the axial displacement of the material to be transferred is prevented by the pressing means as described above, the rigidity of the support member of the material to be transferred is increased to prevent the displacement. There is no need, and therefore, when the transfer material carrier is pressed against the image carrier when the axes of the transfer material carrier and the image carrier are not parallel, the axis of the transfer material carrier is the axis of the image carrier. The support member can be easily deformed so as to be parallel to, so that the contact pressure between the two is substantially uniform over the entire contact range in the axial direction.

Further, by providing a rotating body at the portion of the pressing means or the pressing force supporting member which comes into contact with the material to be transferred material, the material to be transferred material can be brought into and out of contact with the image carrier smoothly. The contact pressure between the material to be transferred and the image carrier can be stably obtained.

[0017]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a plan view showing an image carrier and a transferred material carrier of an embodiment of the image forming apparatus of the present invention.
FIG. 2 is a sectional view taken along line II-II in FIG. 1. The image forming apparatus of this embodiment is a full-color electrophotographic copying machine, and is provided with a photosensitive drum as the image carrier 1 and a transfer drum as the transferred material carrier 2. The photosensitive drum 1 has a shaft 1
is rotatably supported about the shaft 1a by a,
It is rotated by a motor (not shown). The transfer drum 2 is rotatably supported by the shaft 2a about the shaft 2a, and is rotated in synchronization with the photoconductor drum 1 by transmitting the rotation of the photoconductor drum 1 via a gear train (not shown). To be

When performing full-color copying, for example, the image information is decomposed into K, Y, M, and C image information for each color,
The photosensitive drum 1 is irradiated with a laser beam carrying K image information to form an electrostatic latent image on the photosensitive drum 1, and K toner is supplied to the electrostatic latent image to form a K toner image. .
On the other hand, the transfer drum 2 adsorbs a transfer target sheet (not shown) which is a transfer target member and rotates the transfer target sheet toward the photoconductor drum 1 to transfer the transfer target sheet at the transfer position 9. The K toner image on the photosensitive drum 1 is pressed against the photosensitive drum 1 and transferred onto the transfer paper.

After the transfer of the K toner image is completed, the photosensitive drum 1
Is cleaned by a cleaning unit (not shown), and subsequently charged by a charger (not shown). Then, the photosensitive drum 1 is irradiated with a laser beam carrying Y image information, and the electrostatic latent image is formed on the photosensitive drum 1. Form an image,
Y toner is supplied to this electrostatic latent image to form a Y toner image, and this Y toner image is transferred onto the K toner image of the transfer paper which has made one rotation by the transfer drum 2 and transferred thereafter. In the same process, the M toner image and the C toner image are sequentially superimposed and transferred onto the transfer target paper, and full color copying is performed.

The transfer drum 2 is provided between the transfer drum 2 and the photosensitive drum 1 when the transfer paper is clogged between the transfer drum 2 and the photosensitive drum 1 and the transfer of the transfer paper is stopped. In order to make it easy to remove the transfer paper by opening it, the transfer paper is configured so that it can be brought into and out of contact with the photosensitive drum 1 whose arrangement position is fixed. That is, the shaft 4 is bridged between the front and rear frames 3a and 3b, and the front and rear support plates 5a and 5b are rotatably supported by the shaft 4 at a predetermined interval. The shaft 2a of the transfer drum is bridged and supported. A flange 2b is fixedly provided on both ends of the shaft 2a, and the flange 2b supports the front and rear support plates 5
It is fixed to a and 5b.

That is, the transfer drum 2 is supported by a support member 7 composed of support plates 5a and 5b so as to be rotatable around the shaft 4 in the direction of arrow A, and the rotation causes the transfer drum 2 to be a photosensitive drum. It is supposed to be able to move in and out of 1. here,
The transfer drum 2 has a first position (a position shown in the drawing) in which the transfer drum 2 is pressed against the photosensitive drum 1 by a spring 12 that is bridged between the support plate 5a and the frame 3a and between the support plate 5b and the frame 3b. It is held at a second position (not shown) apart from the photosensitive drum 1. Also, the transfer drum 2 is replaced by the cam 1.
4 is rotated from the second position to come into contact with the photoconductor, in order to reduce the collision speed between the photoconductor drum 1 and the transfer drum 2, a space between the support plate 5a and the frame 3a, and a support plate 5b. Damper 1 between the frame and the frame 3b.
3 is provided.

Further, the transfer drum 2 is required to prevent axial misalignment with respect to the photoconductor drum 1 in order to prevent color misregistration when the toner images of respective colors are superposed and transferred as described above. A pressing unit 8 that regulates the axial position of the drum 2 is provided. This pressing means 8 is
The transfer drum 2 is elastically pressed from the outside in the direction of the rotation center axis 2c to regulate the position of the transfer drum 2 in the direction of the rotation center axis 2c. A pressing load 8a slidably penetrating the frames 3a and 3b, a spring seat 8b fixed to the pressing load 8a, and a pressing load provided between the spring seat 8b and the frames 3a and 3b. The pressing load 8a presses the rotary drum 2 with its tip abutting against the flange 2b of the shaft 2a.

The pressing load 8a is composed of the rotation center shaft 2c.
It is desirable to press the transfer drum 2 above, but in the present embodiment, the flange 2b has an opening 2 for pulling out the harness in the transfer drum 2 at the center where the rotation center shaft 2c is located.
Since d is formed, it is arranged so as to press the transfer drum 2 in the cross-sectional area of the shaft 2a while avoiding the opening 2d.

As described above, the pressing load 8a presses the transfer drum 2 within the cross-sectional area of the shaft 2a, so that the pressing load 8a presses the transfer drum 2 outside the cross-sectional area of the shaft 2a. Deflection and flange 2
b by the deformation of b and the deformation of the flange 2b
It is possible to prevent the slidability with respect to the shaft 4 from being deteriorated due to the deformation of a and 5b and the deformation of the support plates 5a and 5b, and the transfer drum 2 can be smoothly rotated.

In this embodiment, the pressing means 8 is used as the transfer drum 2.
Are provided on both sides in the direction of the rotation center axis 2c, and the transfer drum 2 is elastically pressed in the direction of the rotation center axis 2c from both outsides to regulate the axial position of the transfer drum 2 and thus the position shift of the transfer drum 2 in the axial direction. Is being prevented. The pressing loads 8a on both sides of the transfer drum 2 are arranged on a straight line parallel to the rotation center axis 2c.

FIG. 3 is a plan view showing another embodiment. In the above-described embodiment, the pressing means 8 is provided on both sides of the transfer drum 2 in the direction of the rotation center axis 2c, but in this embodiment, the pressing means 8 is provided only on one side in the direction of the rotation center axis 2c of the transfer drum 2, and the other side. A stopper 10, which is a member for supporting the pressing force of the pressing means, is provided on the side of. Since the configuration other than the stopper 10 is the same as that of the embodiment shown in FIGS. 1 and 2, the same components are designated by the same reference numerals and the description thereof will be omitted.

The stopper 10 has a substantially hemispherical front end, a rear end fixed to the frame 3b, and is arranged on the same straight line as the pressing load 7a on the opposite side, and the front end is the shaft of the transfer drum 2. It is brought into contact with the flange 2b of 2a. Also in this embodiment, the transfer drum 2 has the pressing means 8
Since it is pressed toward the stopper 9 in the direction of the rotation center axis 2c, it is sandwiched between the stopper 10 and the pressing means 8 and the axial position is regulated, whereby displacement in the axial direction is prevented.

FIG. 4 shows the pressing means 8 in both the above-mentioned embodiments.
FIG. 5 is a plan view showing another embodiment of FIG.
It is a line sectional view. As shown in the figure, the pressing means 8 is provided at its tip with a roller 8d as a rotating body rotatably supported. A shaft 8 for rotatably supporting the roller 8d
e is a straight line 11 connecting the shaft 4 and the shaft 2a as shown in FIG.
The roller 8d rotates in contact with the flange 2b when the transfer drum 2 rotates about the shaft 4, and as a result, the flange 8d rotates when the transfer drum 2 rotates. The friction between 2b and the pressing means 8 is small, and the transfer drum 2 can be smoothly rotated.

FIG. 6 is a plan view showing another embodiment of the stopper 10 described above. As shown in the figure, the stopper 10 is a roller 10a as a rotating body rotatably supported at its tip.
Is provided. The shaft 10b that rotatably supports the roller 10a is arranged so as to extend in the direction of the straight line 11 shown in FIG. 5, and therefore, when the transfer drum 2 rotates about the shaft 4, the roller 10a is provided. Rotates in contact with the flange 2b, and as a result, the friction between the flange 2b and the stopper 10 during rotation of the transfer drum 2 is small, and the transfer drum 2
Can be rotated smoothly.

[0030]

As described above, in the image forming apparatus of the present invention, as described above, the transfer material carrier is elastically pressed from the outer side in the direction of the rotation center axis of the transfer material carrier. Since the pressing means for restricting the position in the direction of the rotation center axis is provided, the position of the transfer target material carrier is restricted in the axial direction by the pressing means, and thus the color shift due to the positional deviation in the axial direction is prevented. can do.

Further, since the axial displacement of the material to be transferred is prevented by the pressing means, it is not necessary to increase the rigidity of the supporting member of the material to be transferred in order to prevent the displacement. The supporting member can be easily deformed so that the axis of the transferred material carrier becomes parallel to the axis of the image carrier when the transferred material carrier is pressed against the image carrier, and thus the contact pressure between the two Can be made substantially uniform over the entire contact range in the axial direction.

[Brief description of drawings]

FIG. 1 is a plan view of the periphery of an image carrier and a transfer material carrier in one embodiment of an image forming apparatus of the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 shows another embodiment of the image forming apparatus of the present invention,
FIG. 3 is a plan view of the periphery of an image carrier and a transfer material carrier.

FIG. 4 is a plan view showing another example of the pressing member.

5 is a sectional view taken along line VV in FIG.

FIG. 6 is a plan view showing another example of the pressing force support member.

FIG. 7 is a configuration diagram around an image carrier and a transfer material carrier in a conventional image forming apparatus.

8 is a sectional view taken along line VII-VII in FIG.

[Explanation of symbols]

1 Image carrier 2 Material to be transferred 2a axis 2b flange 3a, 3b frame 4 axes 5a, 5b support plate 7 Support member 8 Pressing means 8a Press load 8b spring seat 8c spring 8d roller 9 Transfer position 10 stopper 10a roller 10b axis 11 straight lines 12 spring 13 damper 14 cams

Claims (4)

(57) [Claims] 1. An image carrier on which an electrostatic latent image is formed and toner is supplied to develop the electrostatic latent image, and the toner image formed by the development is transferred to a transfer material. An image forming apparatus, comprising: a transfer material carrier, which is capable of supporting and rotating a transfer material and being provided so as to come in contact with and separate from the image carrier, wherein the transfer material carrier is the transfer material. A pressing means for elastically pressing from the outside of the rotation center axis direction of the carrier to regulate the position of the transferred material support body in the rotation center axis direction, the pressing means comprising:
Inside the outer circumference of the rotary shaft constituting member of the transfer material carrier
Elastically from the outside in the direction of the rotation axis of the transferred material carrier.
An image forming apparatus characterized by being pressed . 2. The pressing means is provided on the transfer target material carrier .
The transfer target material is provided only on one side in the rotation center axis direction.
In the rotation axis direction of the carrier, the other side different from the one side
Side, the pressing force support for supporting the pressing force of the pressing means from the outside.
The image forming apparatus according to claim 1, further comprising a holding member . 3. The pressing means is a pressing direction of the pressing means.
At the tip, contact the transfer target carrier with the image carrier.
The image forming apparatus according to claim 1, further comprising a rotating body that rotates when separated . 4. The pressing force supporting member bears the transferred material.
3. The image forming apparatus according to claim 2 , further comprising: a rotating body that rotates at the time of contacting and separating the transfer target carrier with respect to the image carrier, at a position in contact with the carrier.