JP2019066544A - Transfer device and image forming apparatus - Google Patents

Abstract

To reduce a tensile force when conveyance means is not used compared with that when the conveyance means is used without using means dedicated to reducing the tensile force.SOLUTION: A transfer device (TU) comprises: transfer means (TR); a first support (1) that supports rotating means (6, 7) and conveyance means (TB); a second support (22) that movably supports the first support (1); and tensile force providing means (26) that is supported by the second support (22), is in contact with the conveyance means (TB) at a first position where the transfer means (TR) is in proximity to an image holding body (PR) to provide a tensile force to the conveyance means (TB), and reduces the tensile force provided to the conveyance means (TB) at a second position where the transfer means (TR) is separated from the image holding body (PR) compared with that at the first position.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a transfer device and an image forming apparatus.

  With respect to a technique for adjusting the tension of a belt in a conventional image forming apparatus, a technique described in Patent Document 1 below is known.

  According to JP-A-2016-153847 as Patent Document 1, when the printing operation is started, the belt outer stretching roller (711) moves to widen the contact area with the belt (701) to make the tension When the printing operation is completed, the belt outer tension roller (711) is moved to narrow the contact area with the belt (701), thereby suppressing the plastic deformation of the belt.

JP, 2016-153847, A ("0019"-"0021", "0024"-"0030", "0035"-"00, FIG. 3, FIG. 5, FIG. 7)

  The present invention makes it a technical subject to weaken tension compared with the time of use at the time of non-use of a conveyance means, without using a dedicated means to weaken tension.

In order to solve the above technical problems, the transfer device of the invention according to claim 1 is
A transfer unit disposed opposite to the image carrier, for transferring the image on the surface of the image carrier to a medium;
An endless and elastic conveyance means disposed between the image carrier and the transfer means and stretched by the transfer means to hold and convey the medium on the surface;
Rotation means for supporting the transport means and rotating the transport means;
A first support that supports the transfer unit, the rotation unit, and the transport unit;
A second support movably supporting the first support such that the transfer means moves in a direction toward or away from the image carrier;
At the first position supported by the second support and the transfer means approaches the image holder, the transfer means contacts the transfer means to apply tension to the transfer means, and the transfer means is the image support Tensioning means for reducing tension applied to the transport means at a second position spaced apart from the first position as compared to the first position;
It is characterized by having.

The invention according to claim 2 is the transfer device according to claim 1,
Said tensioning means arranged inside an endless conveying means,
It is characterized by having.

The invention according to claim 3 relates to the transfer device according to claim 2.
The tensioning means rotatably and immovably supported by the second support;
It is characterized by having.

The invention according to claim 4 is the transfer device according to any one of claims 1 to 3.
Said first support movably supported between a first position and a second position about an axis of rotation;
The tension applying means disposed at a position closer to the rotation axis of the first support than the outer peripheral edge of the rotation trajectory of the first support;
It is characterized by having.

The invention according to claim 5 is the transfer device according to claim 4,
The second support is supported movably around the rotation axis with respect to a frame supporting the second support.

The invention according to claim 6 is the transfer device according to any one of claims 1 to 5,
Said tensioning means spaced apart from said transport means at said second position;
It is characterized by having.

The invention according to claim 7 is the transfer device according to any one of claims 1 to 6,
It is characterized in that the axial end portion of the rotation means is formed in a narrowed shape.

In order to solve the above technical problems, an image forming apparatus of the invention according to claim 8 is
An image carrier,
The transfer device according to any one of claims 1 to 7, which is disposed to face the image carrier and transfers an image formed on the image carrier.
It is characterized by having.

According to the inventions of claims 1 and 8, it is possible to weaken the tension as compared to the time of use when the transport means is not used, without using a dedicated means for weakening the tension.
According to the second aspect of the present invention, the contamination of the tension applying means can be reduced as compared with the case where the tension applying means is disposed outside the conveying means.
According to the third aspect of the present invention, the position of the tension applying means can be stabilized and the tension can be stabilized, as compared with the configuration in which the tension applying means is movable.

According to the fourth aspect of the present invention, the tension applying means moves too much relative to the transport means when the first support moves, as compared to the case where the tension applying means is far from the rotation axis. Can be reduced.
According to the fifth aspect of the present invention, even when the second support is movable, the tension applying means moves too much relative to the transport means when the second support moves. Thus, it is possible to reduce large deviations in tension.

According to the sixth aspect of the present invention, plastic deformation of the transfer means can be further suppressed as compared with the case where the tension applying means is not separated from the transfer means.
According to the seventh aspect of the present invention, it is possible to suppress the deviation of the transport means as compared to the case where it does not have a narrowed shape.

FIG. 1 is an explanatory view of an image forming apparatus according to a first embodiment of the present invention. FIG. 2 is an explanatory view of a main part of the transfer device according to the first embodiment, in which the inner unit is moved to the contact position and the outer unit is moved to the image forming position. FIG. 3 is an explanatory view of a main part of the transfer device according to the first embodiment, and an explanatory view of a state in which the inner unit is moved to the separated position. FIG. 4 is an explanatory view of a main part of the transfer device according to the first embodiment, and an explanatory view of a state in which the outer unit is moved to the removal position. FIG. 5 is a perspective view of the main part of the transfer device of the first embodiment. FIG. 6 is an explanatory view of the shift prevention of the transport member of the first embodiment.

Next, specific examples of the embodiment of the present invention (hereinafter referred to as examples) will be described with reference to the drawings, but the present invention is not limited to the following examples.
In order to facilitate understanding of the following description, in the drawings, the longitudinal direction is the X-axis direction, the lateral direction is the Y-axis direction, the vertical direction is the Z-axis direction, and arrows X, -X, Y, -Y, The directions shown by Z and -Z or the sides shown are front, rear, right, left, upper, lower or front, rear, right, left, upper, lower.
Further, in the drawings, those in which “•” is described in “o” means an arrow directed from the back of the paper to the front, and those in which “x” is described in “o” are the front of the paper. It means the arrow from the back to the back.
In the following description using the drawings, illustration of members other than members necessary for the description is appropriately omitted for easy understanding.

FIG. 1 is an explanatory view of an image forming apparatus according to a first embodiment of the present invention.
In FIG. 1, a copying machine U as an example of an image forming apparatus according to the first embodiment is an example of a recording unit, and includes a printer unit U1 as an example of an image recording apparatus. A scanner unit U2 which is an example of a reading unit and is an example of an image reading apparatus is supported above the printer unit U1. On the upper part of the scanner unit U2, an auto feeder U3 as an example of a document conveyance device is supported. The scanner unit U2 of the first embodiment supports a user interface U0 as an example of an input unit. The user interface U0 allows an operator to operate and operate the copying machine U.

  A document tray TG1 as an example of a medium container is disposed above the auto feeder U3. A plurality of documents Gi to be copied can be stacked and stored in the document tray TG1. Below the document tray TG1, a document discharge tray TG2 as an example of a document discharge unit is formed. A document transport roll U3b is disposed along the document transport path U3a between the document tray TG1 and the document discharge tray TG2.

A platen glass PG, which is an example of a transparent document table, is disposed on the upper surface of the scanner unit U2. In the scanner unit U2 of the first embodiment, an optical system A for reading is disposed below the platen glass PG. The reading optical system A of the first embodiment is supported movably in the left and right direction along the lower surface of the platen glass PG. The reading optical system A normally stops at the initial position shown in FIG.
An imaging device CCD as an example of an imaging member is disposed on the left side of the optical system A for reading. An image processing unit GS is electrically connected to the imaging device CCD.
The image processing unit GS is electrically connected to the write circuit DL of the printer unit U1. The write circuit DL is electrically connected to an exposure apparatus ROS as an example of a latent image forming apparatus.

  In the printer unit U1, a photosensitive drum PR as an example of an image carrier is disposed. Around the photosensitive drum PR, a charging roll CR as an example of a charging member, a developing device G, a transfer unit TU as an example of a transfer device, and a drum cleaner CLp as an example of a cleaning device are disposed.

Below the transfer unit TU, paper feed trays TR1 to TR4 as an example of a medium container are disposed. A conveyance path SH1 extends from each of the paper feed trays TR1 to TR4. A pickup roll Rp as an example of a medium takeout member, a loosening roll Rs as an example of a loosening member, a conveyance roll Ra as an example of a conveyance member, and a registration roll Rr as an example of a delivery member are disposed in the conveyance path SH1. There is.
On the right side of the transfer unit TU, a fixing device F having a heating roll Fh and a pressure roll Fp is disposed. The fixing device F and the sheet discharge tray TRh are connected by a discharge path SH2. The discharge path SH2 and the registration roll Rr are connected by a reverse path SH3. In the discharge path SH2, a transport roll Rb capable of forward and reverse rotation and a discharge roll Rh are disposed.

(Description of the image forming operation)
The plurality of documents Gi accommodated in the document tray TG1 sequentially pass through the reading position of the document on the platen glass PG, and are discharged to the document discharge tray TG2.
When a document is automatically conveyed for copying using the auto-feeder U3, while the optical system A for reading is stopped at the initial position, each document sequentially passes the reading position on the platen glass PG Expose Gi.
When the operator places the original document Gi by hand on the platen glass PG for copying, the optical system A for reading moves in the left-right direction, and the original document on the platen glass PG is scanned while being exposed.
Reflected light from the document Gi passes through an optical system A for reading and is condensed on an imaging device CCD. The image pickup device CCD converts the reflected light of the original collected on the image pickup surface into an electric signal.

The image processing unit GS converts a read signal input from the image pickup device CCD into a digital image signal, and outputs the digital image signal to the write circuit DL of the printer unit U1. The write circuit DL outputs a control signal corresponding to the input image write signal to the exposure device ROS.
The charging roll CR charges the surface of the photosensitive drum PR in the charging area Q0. The exposure device ROS outputs a laser beam L to form a latent image on the surface of the photosensitive drum PR in the latent image forming area Q1. The latent image on the surface of the photosensitive drum PR is developed into a visible image by the developing device G in the developing area Q2. The transfer roll TR of the transfer unit TU transfers the visible image of the surface of the photosensitive drum PR onto the recording sheet S as an example of the medium transported on the transport path SH1 in the transfer area Q3. The transfer conveyance belt TB of the transfer unit TU conveys the recording sheet S to the fixing device F. The fixing device F fixes the visible image transferred to the recording sheet S. The recording sheet S which has passed through the fixing device F is conveyed to the reverse path SH3 when double-sided printing is performed, and is discharged by the discharge roll Rh when discharged to the discharge tray TRh.

(Description of transfer device)
FIG. 2 is an explanatory view of a main part of the transfer device according to the first embodiment, in which the inner unit is moved to the contact position and the outer unit is moved to the image forming position.
FIG. 3 is an explanatory view of a main part of the transfer device according to the first embodiment, and an explanatory view of a state in which the inner unit is moved to the separated position.
FIG. 4 is an explanatory view of a main part of the transfer device according to the first embodiment, and an explanatory view of a state in which the outer unit is moved to the removal position.
FIG. 5 is a perspective view of the main part of the transfer device of the first embodiment.

  In FIGS. 2 to 5, a transfer unit TU as an example of the transfer device according to the first embodiment has a transfer roll TR as an example of the transfer unit. Both ends in the axial direction (front-rear direction) of the transfer roller TR are supported by an inner unit frame 1 as an example of a first support. The inner unit frame 1 is formed in a plate shape extending in the left-right direction, and is disposed to face each other in the front-rear direction. The inner unit frame 1 supports a motor unit 2 as an example of a drive source. The motor unit 2 rotationally drives the transfer roll TR.

On the inner unit frame 1, a first driven roller 6 as an example of a rotating member is rotatably supported at a position downstream of the transfer roller TR in the sheet conveying direction.
Further, on the downstream side of the first driven roller 6, a second driven roller 7 as an example of a rotation unit is rotatably supported by the inner unit frame 1. In FIG. 5, in the second driven roller 7 of the first embodiment, a narrowed portion 7 a as an example of the anti-shifting portion is formed at both end portions in the axial direction.

FIG. 6 is an explanatory view of the shift prevention of the transport member of the first embodiment.
Here, the transfer conveyance belt TB of the first embodiment is configured of a rubber belt as an example of an elastic material. In FIG. 6, when tension is applied to the transfer and transport belt TB as an example of the transport means, both ends of the narrowed portion 7a are pressed so as to be wound around the narrowed portion 7a. Therefore, a force 7 b having a component directed inward in the axial direction acts on both ends of the transfer conveyance belt TB. Therefore, the transfer conveyance belt TB of Example 1 is difficult to be shifted to one side in the axial direction.
The rotation shaft 8 of the second driven roller 7 extends axially outward, and is rotatably supported by a frame (not shown) of the copying machine U.

  In FIGS. 2 to 5, in the inner unit frame 1, on the opposite side of the rotating shaft 8, a spring accommodating box 11 as an example of a first actuated portion is disposed. The spring accommodation box 11 is supported by the inner unit frame 1 so as to be movable in the vertical direction, that is, in the direction in which the transfer roll TR approaches and separates from the photosensitive drum PR. The spring accommodating box 11 accommodates a coil spring 12 as an example of a biasing unit. The coil spring 12 exerts an elastic force that pushes the inner unit frame 1 upward, and applies the transfer pressure of the transfer area Q3 where the transfer roll TR contacts the photosensitive drum PR. In addition, the spring storage box 11 and the coil spring 12 are disposed in a pair in the front and rear direction.

  The inner unit 13 of the first embodiment is configured by the transfer roll TR, the transfer conveyance belt TB, and members denoted by reference numerals 1 to 12. The inner unit 13 according to the first embodiment is disposed between the contact position as an example of the first position shown in FIG. 2 and the separation position as an example of the second position shown in FIG. It is movably supported.

Below the spring accommodating box 11, a first cam 21 as an example of a first actuation means is disposed. The first cam 21 is disposed in contact with the lower surface of the spring storage box 11.
The rotation shaft 21 a of the first cam 21 is rotatably supported by an outer unit frame 22 as an example of a second support. The outer unit frame 22 is disposed in a pair on the outer side in the front-rear direction with respect to the inner unit frame 1. The outer unit frame 22 is formed in a plate shape extending in the left-right direction.

In FIG. 5, the outer unit frame 22 of the first embodiment is rotatably supported with respect to the rotation shaft 8. Accordingly, the outer unit frame 22 of the first embodiment is also supported rotatably about the rotation shaft 8 with respect to a frame (not shown) of the copying machine U.
In the outer unit frame 22 of the first embodiment, a butting projection 22a as an example of a positioning portion is formed at the upper left end. In FIGS. 2 to 4, the abutment projection 22 a contacts the drum frame 23 as an example of a frame supporting the photosensitive drum PR to position the outer unit frame 22. Therefore, when the outer unit frame 22 is positioned, the transfer roll TR supported via the first cam 21 and the inner unit frame 1 is positioned relative to the photosensitive drum PR.

  In FIGS. 2 to 4, a drive system 24 for controlling the rotation of the first cam 21 is supported by the rear unit frame 22 on the rear side. The drive system 24 includes a motor 24a as an example of a drive source and a plurality of gears 24b and 24c. The motor 24 a according to the first embodiment operates in response to a control signal from the control unit C. In the first embodiment, the motor 24a rotates the first cam 21 to move it to the contact position shown in FIG. 2 when the image forming operation is started, and rotates the first cam 21 when the image forming operation is finished. It is configured to be moved to the separated position shown in FIG.

  In FIGS. 2 to 5, tension rolls 26 as an example of tension applying means are supported between the outer unit frames 22. The tension roll 26 of the first embodiment is rotatably and immovably supported relative to the outer unit frame 22. Further, the tension roll 26 is disposed inside the transfer conveyance belt TB. Furthermore, at the position shown in FIG. 2, the tension roll 26 of the first embodiment is set at a position where it contacts the inner surface of the transfer and transport belt TB to apply tension to the transfer and transport belt TB. Further, at the position shown in FIG. 3, the tension roll 26 is separated from the transfer and transport belt TB, and the tension of the transfer and transport belt TB is set to be weaker than in the case of FIG.

Although the belt cleaner CLb as an example of a cleaning device for cleaning the transfer conveyance belt TB is supported by the outer unit frame 22, it is not shown in FIG.
The outer unit 27 of the first embodiment is configured by the members given the reference numerals 22 to 26. As described above, the outer unit 27 is supported movably between the image forming position shown in FIG. 2 and the removal position shown in FIG. 4 around the rotation shaft 8.

  In FIGS. 2 to 4, a second cam 31 as an example of a second operation member is disposed below the outer unit frame 22. The second cam 31 is disposed in contact with the lower surface of the outer unit frame 22. The rotation shaft 31 a of the second cam 31 is connected to a handle 32 as an example of the operation member. Therefore, when the operator operates the handle 32, the second cam 31 is configured to rotate.

(Operation of Example 1)
In the copying machine U according to the first embodiment having the above-described configuration, when the image forming operation is started, the first cam 21 is actuated to move the inner unit 13 to the contact position shown in FIG. Therefore, the transfer roll TR and the photosensitive drum PR face each other with the transfer conveyance belt TB in between and make contact. At this time, the tension roll 26 presses against the transfer conveyance belt TB to apply a predetermined tension. Therefore, image formation is performed in this state.

When the image forming operation is completed, the first cam 21 is actuated to move the inner unit 13 to the separated position shown in FIG. Therefore, the transfer roll TR is separated from the photosensitive drum PR. At this time, the tension applied to the transfer conveyance belt TB by the tension roll 26 is reduced.
Therefore, in Example 1, the tension is increased or decreased using a configuration in which the transfer transport belt TB and the transfer roll TR are separated from the photosensitive drum PR without using a dedicated component for increasing or decreasing the tension of the transfer transport belt TB. Is possible. Therefore, it is possible to weaken the tension of the transfer transport belt TB when it is not used as compared to when it is used, without using a dedicated member or means for weakening the tension.

  In the configuration using the transfer conveyance belt TB, there is a limit in improving the accuracy of the parallelism of the transfer roll TR and the driven rolls 6 and 7 in order to prevent the deviation and meandering of the transfer conveyance belt TB. Therefore, although a mechanism for preventing the belt from shifting is required, in the case of using an elastic belt having stretchability as in Example 1, as shown in FIG. It is possible to control the offset of the transfer transport belt TB. However, a high tension is required so that the transfer transport belt TB wraps around the constriction portion 7a. If this high tension is continuously applied, the transfer transport belt TB may be plastically deformed with time. When plastically deformed, the tension decreases, and there is a risk of deviation and meandering. In addition, if high tension is continuously applied, the transfer transport belt TB may be cracked or cracked. If a crack or the like occurs, a cleaning failure of the belt cleaner CLb may occur, which may contaminate the recording sheet S.

Even when the configuration of the meandering prevention of the transfer and transport belt TB is different, there is no difference in the occurrence of plastic deformation by continuously applying tension.
Further, the transfer / transport belt TB is in contact with the photosensitive drum PR at a transfer pressure set in advance in the transfer area Q3. If the transfer belt TB continues to be in contact with the photosensitive drum PR even if only the tension of the transfer transport belt TB is weakened, the portion sandwiched between the transfer roll TR and the photosensitive drum PR is plastically deformed and the transfer transport belt TB There is a risk of wrinkles If the transfer transport belt TB is wrinkled, there is a possibility that periodical speed fluctuation may occur in the rotation of the transfer transport belt TB.

In the configuration described in Patent Document 1, a dedicated mechanism for increasing or decreasing the tension of the belt is described, and the configuration is temporarily different from the configuration in which the belt is in contact with or separated from the photosensitive member or the like. Therefore, there is a problem that the number of parts increases and the configuration becomes complicated.
On the other hand, in the first embodiment, the transfer conveyance belt TB can be brought into contact with and separated from the photosensitive drum PR simply by moving the inner unit 13, and the tension can also be increased or decreased. Therefore, it is possible to suppress plastic deformation of the transfer conveyance belt TB with a simple configuration. Therefore, the occurrence of the deviation of the transfer transport belt TB or the occurrence of the cleaning failure is also reduced.

In the first embodiment, when the image forming operation is completed, the photosensitive drum PR and the transfer conveyance belt TB are separated from each other by moving to the separated position shown in FIG. Although it is possible to weaken the contact pressure without completely separating the photosensitive drum PR and the transfer conveyance belt TB in the separated position shown in FIG. The plastic deformation of the transfer conveyance belt TB can be further suppressed, and the life of the transfer conveyance belt TB can be extended. In the completely separated state, the jammed paper can be easily removed when the image forming operation is completed due to a paper jam or the like.
Further, in the transfer unit TU of the first embodiment, when the handle 32 is operated, as shown in FIG. 4, both the inner unit 13 and the outer unit 27 are separated from the photosensitive drum PR. Therefore, it is easy to replace the transfer unit TU or to replace the unit on the photosensitive drum PR side. It is also possible to eliminate paper jams.

  Further, unlike the belt outer tension roller of Patent Document 1, the tension roll 26 of the first embodiment is in contact with the inside of the transfer conveyance belt TB. The outer surface of the transfer and transport belt TB may be contaminated with a developer, paper dust, and the like. When the tension roll 26 comes in contact with the outer surface of the transfer and transport belt TB, the tension roll 26 may be contaminated with time. If the tension roll 26 is soiled, the dirt of the tension roll 26 will be transferred again onto the transfer transport belt TB, and the transfer transport belt TB may be soiled, and the recording sheet S and the photosensitive drum PR may be soiled. On the other hand, in the first embodiment, the tension roll 26 is in contact with the inside of the transfer conveyance belt TB, and the tension roll 26 is not easily soiled.

  Furthermore, the tension roll 26 of the first embodiment is movably supported by the outer unit frame 22. Therefore, the position of the tension roll 26 can be stabilized more easily than in the case where the tension roll 26 is supported so as to be movable vertically and horizontally, or pressed so as to apply a tension by a spring. Therefore, the tension of the transfer conveyance belt TB can be reliably increased or decreased. Also, the configuration is simplified as compared to the movable configuration.

Further, in the transfer unit TU of the first embodiment, the tension roll 26 is disposed at a position closer to the rotation axis 8 than the first driven roll 6 and the transfer roll TR on the outer peripheral edge of the rotation trajectory. When the position of the tension roll 26 is far from the rotation axis 8, the radius becomes large even if the rotation angle around the rotation axis 8 is small, so the relative movement distance of the tension roll 26 with respect to the transfer transport belt TB is become longer. In this state, when a positional deviation occurs due to rattling or the like when the transfer conveyance belt TB contacts or separates from the photosensitive drum PR, the relative positional deviation of the stretching roll 26 relative to the transfer conveyance belt TB becomes large. Therefore, the deviation of the applied tension is increased. On the other hand, in the first embodiment, the tension roll 26 is disposed at a position close to the rotating shaft 8, so that the increase and decrease of the tension does not become too large, and the sensitivity can be increased or decreased.
Further, in the transfer unit TU according to the first embodiment, the outer unit 27 is also movably supported using the common rotation shaft 8 with the inner unit 13. Therefore, even if a shift occurs when the outer unit 27 moves, it is suppressed that the increase and decrease of the tension applied by the tension roll 26 becomes too large.

(Modification example)
As mentioned above, although the Example of this invention was explained in full detail, this invention is not limited to the said Example, A various change is made in the range of the summary of this invention described in the claim. Is possible. Modifications (H01) to (H08) of the present invention are exemplified below.
(H01) In each of the above embodiments, the copying machine U as an example of the image forming apparatus has been exemplified, but the invention is not limited to this, and can be applied to a printer, a fax machine, or a multifunction machine having a plurality of these functions. . Further, the present invention is not limited to an image forming apparatus for single color development, and may be configured by a multicolor, so-called color image forming apparatus.

(H02) In the above embodiment, the tension roll 26 is preferably disposed inside the transfer and transport belt TB, but may be configured to be in contact with the outer surface of the transfer and transport belt TB. At this time, it is desirable to provide a cleaner for cleaning the tension roll 26.
(H03) In the above embodiment, the tension roll 26 is preferably configured so as not to move to the outer unit frame 22, but is not limited thereto. It is also possible to movably support the transfer conveyance belt TB in a direction to apply tension and to apply tension to the transfer conveyance belt TB by a spring or the like.

(H04) In the above embodiment, the inner unit 13 and the outer unit 27 are illustrated as rotatable around the rotation shaft 8, but the present invention is not limited thereto. For example, instead of the rotating configuration, it is possible to vertically move up and down. In addition, although it is desirable to reduce the number of parts by making the rotating shafts 8 of the inner unit 13 and the outer unit 27 in common, it is also possible to provide rotating shafts separately.
(H05) In the above embodiment, although the tension roll 26 is desirably disposed at a position close to the rotation axis 8, it is also possible to place the tension roll 26 at a remote position.

(H06) In the above embodiment, it is desirable to completely separate the transfer conveyance belt TB and the photosensitive drum PR at the separated position, but not completely separated, and contact is made in a state where the contact pressure is weak. It is also possible. Further, the relationship between the transfer conveyance belt TB and the tension roll 26 is also the same, and it may be configured to be completely separated, or may be configured to be in contact in a state where the tension is weak.
(H07) In the above embodiment, although it is desirable that the outer unit 27 be configured to be rotatable about the rotary shaft 8, the outer unit 27 may be configured to be immovable.

(H08) In the above embodiment, the transfer conveyance belt TB is exemplified as the conveyance member, but the invention is not limited thereto. It is applicable to any conveyance belt which holds and conveys a medium.

1 ... first support,
6, 7 ... rotating means,
8 ... rotation axis,
22 ... second support,
26 ... tension applying means,
PR: Image holder,
S: Medium,
TB: Transport means,
TR: Transfer means,
TU: Transfer device,
U: Image forming apparatus.

Claims (8)

A transfer unit disposed opposite to the image carrier, for transferring the image on the surface of the image carrier to a medium;
An endless and elastic conveyance means disposed between the image carrier and the transfer means and stretched by the transfer means to hold and convey the medium on the surface;
Rotation means for supporting the transport means and rotating the transport means;
A first support that supports the transfer unit, the rotation unit, and the transport unit;
A second support movably supporting the first support such that the transfer means moves in a direction toward or away from the image carrier;
At the first position supported by the second support and the transfer means approaches the image holder, the transfer means contacts the transfer means to apply tension to the transfer means, and the transfer means is the image support Tensioning means for reducing tension applied to the transport means at a second position spaced apart from the first position as compared to the first position;
A transfer device characterized by comprising: Said tensioning means arranged inside an endless conveying means,
The transfer device according to claim 1, further comprising: The tensioning means rotatably and immovably supported by the second support;
The transfer device according to claim 2, further comprising: Said first support movably supported between a first position and a second position about an axis of rotation;
The tension applying means disposed at a position closer to the rotation axis of the first support than the outer peripheral edge of the rotation trajectory of the first support;
The transfer device according to any one of claims 1 to 3, further comprising: The transfer device according to claim 4, wherein the second support is supported movably about the rotation axis with respect to a frame supporting the second support. Said tensioning means spaced apart from said transport means at said second position;
The transfer device according to any one of claims 1 to 5, further comprising: The transfer device according to any one of claims 1 to 6, wherein an axial end portion of the rotation means is formed in a narrowed shape. An image carrier,
The transfer device according to any one of claims 1 to 7, which is disposed to face the image carrier and transfers an image formed on the image carrier.
An image forming apparatus comprising:

Images