JP2000227691A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To fix the position of a secondary transfer area by fixing the position of a secondary transfer unit with respect to an intermediate transfer belt. SOLUTION: The image forming device comprises a belt module provided with a belt frame FB having a front frame FBF and a rear frame, a secondary transfer unit UT movably supported between an attached position below the belt module and a drawn position where it is drawn to the front, and belt-frame- and-secondary-transfer-unit automatic connecting members (2f, 19a, 2r, and 20a) having rear connecting members (2r, 20a) which, when the secondary transfer unit UT is moved from the drawn position to the attached position, automatically connects a secondary-transfer-unit rear wall 20 and the rear frame so that they cannot move vertically with respect to each other, and having front connecting members (2f, 19a) which automatically connect a secondary-transfer- unit front wall 19 and the front frame FBF so that they cannot move vertically with respect to each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a toner image on the surface of a rotating photosensitive member, transferring the toner image to an intermediate transfer belt, and transferring the primary transfer toner image on the intermediate transfer belt to a secondary image. An image forming apparatus for performing secondary transfer to a final transfer material such as a recording sheet by a secondary transfer device in a transfer area;
In particular, between a withdrawal position where the secondary transfer unit including the secondary transfer unit is pulled out of the image forming apparatus main body and a mounting position where the secondary transfer unit is inserted into the image forming apparatus main body and mounted below the intermediate transfer belt. The present invention relates to an image forming apparatus configured so as to be able to enter and exit.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus has been used in which the secondary transfer unit can enter and exit the image forming apparatus main body. As a secondary transfer device used in such an image forming apparatus, a secondary transfer corotron, a secondary transfer roll, and the like are known. The secondary transfer roll is held at a separated position away from the intermediate transfer belt except during the secondary transfer operation.
It is held at the secondary transfer position (the position where it is pressed against the intermediate transfer belt) only during the next transfer operation.

[0003]

In the conventional image forming apparatus in which the secondary transfer unit can enter and exit the image forming apparatus main body, the secondary transfer unit is not fixed to the intermediate transfer belt. For this reason, when the toner image on the intermediate transfer belt is secondarily transferred to the recording sheet,
There is a problem that it is difficult to determine the position of the secondary transfer area formed between the secondary transfer unit and the secondary transfer unit. Especially as a secondary transfer unit,
When the secondary transfer roll is used, the frame supporting the secondary transfer roll moves in a direction away from the intermediate transfer belt due to the reaction force of the pressing force of the secondary transfer roll pressed against the intermediate transfer belt during the secondary transfer operation. Receive strength. For this reason, there arises a problem that the shape of the nip, which is a pressure contact area between the intermediate transfer belt and the secondary transfer roll, changes, and that an appropriate pressure contact force (nip pressure) cannot be obtained. Also,
When the reaction force of the pressing force acts on the frame of the image forming apparatus, the frame of the image forming apparatus may bend and deform.

[0004] In view of the above problems, the present invention provides the following (O0
1) and (O02) are to be described. (O01) To fix the position of the secondary transfer area by fixing the position of the secondary transfer device with respect to the intermediate transfer belt. (O02) To be able to appropriately maintain the pressing force between the secondary transfer roll and the intermediate transfer belt when the secondary transfer roll is used as the secondary transfer device.

[0005]

Next, a description will be given of the present invention which has solved the above-mentioned problems. In the description of the present invention, reference numerals in parentheses added after constituent elements of the present invention denote constituent elements of the present invention. Reference numerals of corresponding components of the embodiment described later. The reason why the present invention is described in association with the reference numerals of the components of the embodiments described later is to facilitate understanding of the present invention, and not to limit the scope of the present invention to the embodiments.

(A) The image forming apparatus according to the present invention has the following requirements (A01) to (A05). (A01) Rotation extending in the front-rear direction. A photoreceptor (PR) on which a toner image is formed on a surface rotating and rotating about an axis, a belt frame (FB) having a front frame (FBF) and a rear frame (FBR) spaced apart before and after (A02); A plurality of belt supporting rolls (Rd, Rd, Rt, Rw, Rf, T2a) including a belt driving roll (Rd) supported at both front and rear ends by the front frame (FBF) and the rear frame (FBR). Rt, Rw, Rf, T2a) and the plurality of belt support rolls (Rd, Rt, Rw, Rf, T2a), which are rotatably supported and transfer the toner image on the surface of the photoconductor (PR). Next transfer area ( 3) and an intermediate transfer belt (B) rotating sequentially passing through a secondary transfer area (Q4) for secondary transfer of the primary-transferred toner image to the recording sheet (S); and the belt frame (FB). (PR) supported by the first transfer area (Q3)
A primary transfer device (T1) for primary-transferring the toner image on the surface to the intermediate transfer belt (B).
M), (A03) a recording sheet conveying device (SH) for sequentially conveying the recording sheet (S) to the secondary transfer area (Q4) and the fixing area (Q5), (A04) the belt module (B)
M) A secondary transfer unit (U) movably supported back and forth between a lower mounting position and a pulled-out position pulled forward.
T), wherein the secondary transfer unit rear walls (20) and 2
The front wall of the next transfer unit (19) and the secondary transfer area (Q
4) a secondary transfer unit (UT) having a secondary transfer unit (T2) for secondary transfer of the primary transfer toner image of the intermediate transfer belt (B) passing through the recording sheet (S);
(A05) When the secondary transfer unit (UT) is moved from the pull-out position to the mounting position, the rear wall (20) of the secondary transfer unit and the rear frame (FBR) are automatically immovable relative to each other vertically and horizontally. Rear connecting member (2
r, 2r, 20a, 20a) and a front connecting member (2f, 2f, 2f) for automatically connecting the front wall (19) of the secondary transfer unit and the front frame (FBF) so as not to be vertically and horizontally relative movable.
2f, 19a, 19a) and an automatic coupling member (2f, 2f, 19a, 19a,
2r, 2r, 20a, 20a) and a unit rear wall side connecting member (2) provided on the secondary transfer unit rear wall (20).
0a, 20a) and the rear connection member (2r, 2r, 20a, 20a) configured by the rear frame-side connection member (2r, 2r) provided on the rear frame (FBR);
The front part constituted by a unit front wall side connecting member (19a, 19a) provided on the secondary transfer unit front wall (19) and a front frame side connecting member (2f, 2f) provided on the front frame (FBF). Part connecting member (2
f, 2f, 19a, 19a) and the belt frame / secondary transfer unit automatic connecting member (2f, 2f, 19a,
19a, 2r, 2r, 20a, 20a).

(Operation of the Present Invention) In the image forming apparatus of the present invention having the above-described configuration, a toner image is formed on the surface of the photoreceptor (PR) which rotates around a rotation axis extending in the front-rear direction. The belt module (BM) is a belt frame (F
B), a plurality of belt supporting rolls (Rd, Rt, Rw, Rf, T2a) including a belt driving roll (Rd) and a plurality of driven rolls (Rt, Rw, Rf, T2a), an intermediate transfer belt (B), A front frame (FBF) and a rear frame (FBR) which have a secondary transfer device (T1) and are arranged separately from the front and rear of the belt frame (FB) are connected to the plurality of belt support rolls (Rd, Rt, Rw, Rf). , T2a). The belt support rolls (Rd, Rt, R
The intermediate transfer belt (B) rotatably supported by (w, Rf, T2a) sequentially moves in the primary transfer area (Q3) and the secondary transfer area (Q4). In the primary transfer area (Q3), a primary transfer device (T1) supported by the belt frame (FB) transfers a toner image on the surface of the photoconductor (PR) passing through the primary transfer area (Q3). Intermediate transfer belt (B)
First transfer. The recording sheet transport device (SH) sequentially transports the recording sheet (S) to the secondary transfer area (Q4) and the fixing area (Q5).

The secondary transfer unit (UT) has a rear wall (20) of the secondary transfer unit, a front wall (19) of the secondary transfer unit, and a secondary transfer unit (T2), and is below the belt module (BM). Is supported so as to be able to move back and forth between a mounting position and a pulling-out position pulled forward. The secondary transfer unit (T2) transfers the primary transfer toner image of the intermediate transfer belt (B) passing through the secondary transfer area (Q4) to a recording sheet (S).
Is secondarily transferred.

Belt frame / secondary transfer unit automatic connection members (2f, 2f, 19a, 19a, 2r, 2r, 20a,
20a) is constituted by a unit front wall side connecting member (19a, 19a) provided on the secondary transfer unit front wall (19) and a front frame side connecting member (2f, 2f) provided on the front frame (FBF). Front connecting member (2f, 2f, 19a, 19a) and a unit rear wall side connecting member (20 provided on the rear wall (20) of the secondary transfer unit.
a, 20a) and a rear connecting member (2r, 2r, 20a, 20a) constituted by a rear frame side connecting member (2r, 2r) provided on the rear frame (FBR),
The rear connecting member (2r, 2r, 20a, 20a) is configured to move the secondary transfer unit (UT) from the pull-out position to the mounting position when the secondary transfer unit rear wall (20) and the rear frame ( FBR) is automatically connected so that it cannot move up, down, left, and right relative to each other. The front connecting member (2f, 2f,
19a, 19a) also automatically connects the front wall (19) of the secondary transfer unit and the front frame (FBF) so that they cannot move vertically and horizontally relative to each other. For this reason, the belt module (BM) and the secondary transfer unit (UT) are connected so as not to be able to move vertically and horizontally relative to each other, so that the belt module (BM) and the secondary transfer unit (UT) are separated from each other. There is no. Therefore, the belt module (B
M) with respect to the intermediate transfer belt (B) supported by
Since the position of the secondary transfer unit (T2) of the next transfer unit (UT) is fixed, the position of the secondary transfer area (Q4) can be fixed.

When a secondary transfer roll (T2b) is used as the secondary transfer unit (T2), the secondary transfer roll (T2) of the secondary transfer unit (UT) is used during the secondary transfer operation.
When b) is pressed against the intermediate transfer belt (B) supported by the belt module (BM), the belt module (BM) and the secondary transfer unit (UT) are connected. The secondary transfer roll (T2b) and the intermediate transfer belt (B) are not separated by the reaction force. For this reason, the pressing force between the secondary transfer roll (T2b) and the intermediate transfer belt (B) can be appropriately maintained.

[0011]

(Embodiment 1) An image forming apparatus according to Embodiment 1 of the present invention has the following requirement (A06) in the present invention, and (A06) the intermediate The rear connecting members (2r, 2r, 20a, 20a, 20b, 20c) provided at positions below the transfer belt (B) and upstream and downstream of the secondary transfer area (Q4) in the sheet conveying direction, respectively.
20a) and the front coupling members (2f, 2f, 2f, 2c) provided at a position above the secondary transfer device (T2) and upstream and downstream of the secondary transfer region (Q4) in the sheet conveying direction.
2f, 19a, 19a).
Secondary transfer unit automatic connection member (2f, 2f, 19a, 1
9a, 2r, 2r, 20a, 20a).

(Operation of the First Embodiment) In the image forming apparatus of the first embodiment of the present invention having the above-described configuration, the belt frame / secondary transfer unit automatic connection members (2f, 2f, 19) are provided.
a, 19a, 2r, 2r, 20a, 20a), the rear connecting member (2r, 2r, 20a, 20a) is located below the intermediate transfer belt (B) and in the secondary transfer area (Q4).
And the front connecting members (2f, 2f, 19a, 19a) are located above the secondary transfer unit (T2) and in the secondary transfer area (Q4).
Are provided on the upstream side and the downstream side in the sheet conveying direction. For this reason, the belt frame (FB) and the secondary transfer unit (UT) are connected to each other on both sides of the secondary transfer area (Q4) in the sheet conveying direction so as to be unable to move vertically and horizontally.
Even if a force acts on the secondary transfer device (T2) in a direction to separate it from the intermediate transfer belt (B), the secondary transfer area (Q
As compared with the case where the belt frame (FB) and the secondary transfer unit (UT) are connected at a position other than both sides in the sheet conveyance direction of 4), the secondary transfer unit ( The position of T2) is fixed.

(Embodiment 2) An image forming apparatus according to Embodiment 2 of the present invention is characterized in that the following requirements (A07) and (A08) are provided in the present invention or Embodiment 1 of the present invention. (A07) The secondary transfer device (T2) constituted by a secondary transfer roll (T2b), (A08) The secondary transfer roll (T2b) is separated from the intermediate transfer belt (B). A secondary transfer roll moving device (18, 18, LR, LR) for moving between a position and a secondary transfer position pressed against the intermediate transfer belt (B).

(Operation of the Second Embodiment) In the image forming apparatus of the second embodiment of the present invention having the above-described configuration, the secondary transfer roll moving device (18, 18, LR, LR) includes the secondary transfer roller. The secondary transfer roll (T2b) constituting the container (T2)
The intermediate transfer belt (B) is moved between a separated position distant from the intermediate transfer belt (B) and a secondary transfer position pressed against the intermediate transfer belt (B). When the secondary transfer roll (T2b) moves to the secondary transfer position, the secondary transfer roll (T2b) is caused to react with the intermediate transfer belt (B) by a reaction force of a pressing force against the intermediate transfer belt (B). To move in a direction away from it. However, since the belt module (BM) and the secondary transfer unit (UT) are connected, the secondary transfer roll (T2b) and the intermediate transfer belt (B)
Never leave. Therefore, the same effects as those of the present invention are provided.

[0015]

Next, specific examples (embodiments) of the embodiment of the image forming apparatus of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments. In addition,
In order to facilitate understanding of the following description, in the drawings,
The front-rear direction is the X-axis direction, the right-left direction is the Y-axis direction, the up-down direction is the Z-axis direction, and the directions indicated by arrows X, -X, Y, -Y, Z, -Z or the sides indicated are front, rear, Right, left, upper, lower, or front, rear, right, left, upper, lower. Also, in the figure, those in which “•” is described in “○” mean an arrow pointing from the back of the paper to the front,
A mark with "x" in "o" means an arrow pointing from the front to the back of the paper.

(Embodiment) FIG. 1 is an overall explanatory view of an embodiment of the image forming apparatus of the present invention. FIG. 2 is an enlarged view of a main part of FIG. FIG. 3 is a view of the same part as FIG. 2 but showing a different state. FIG. 4 is an explanatory diagram of a front portion (front frame) of the belt frame. FIG. 5 is an explanatory diagram of a rear portion (rear frame) of the belt frame. FIG. 6 is an explanatory diagram of a support structure of the secondary transfer unit. FIG. 7 is a perspective view of the secondary transfer unit as viewed from the rear side. 8A and 8B are explanatory views of a sheet guide on the upstream side of the secondary transfer area. FIG. 8A is a view showing a state in which the secondary transfer unit is held at a secondary transfer position (a position where secondary transfer operation is possible).
FIG. 5 is a diagram illustrating a state in which the secondary transfer unit has moved to a separation position (a position separated from the intermediate transfer belt and capable of moving in and out of the image forming apparatus main body).

In FIG. 1, the image forming apparatus U includes an automatic document feeder U1 and an image forming apparatus main body (copier) U2 having a platen glass PG for supporting the same. The automatic document feeder U1 includes a document feed tray TG1 on which a plurality of documents Gi to be copied are placed in an overlapping manner.
And a document discharge tray TG2 from which a document Gi conveyed from the document feed tray TG1 through a copy position (document reading position) on the platen glass PG is discharged.
The image forming apparatus main body U2 has a UI (user interface) through which a user inputs an operation command signal such as copy start, an exposure optical system A, and the like. The reflected light from the document Gi conveyed onto the platen glass PG by the automatic document feeder U2 or a document (not shown) manually placed on the platen glass PG is transmitted through the exposure optical system A to the CCD. R (red), G (green), B
(Blue) electrical signal. The IPS (Image Processing System) converts the RGB electrical signals into K
The image data is converted into (black), Y (yellow), M (magenta), and C (cyan) image data, temporarily stored, and output to the laser drive circuit DL at a predetermined timing.

The surface of the image carrier (photosensitive drum) PR, which rotates in the direction of the arrow Ya, is uniformly charged by the charger CR in the charging area Q0, and the latent image writing position Q1, the developing area Q2, and the developing area Q1, The sheet sequentially passes through the next transfer area Q3. An ROS (latent image writing device) driven by the laser driving circuit DL performs exposure scanning with the laser beam L at the latent image writing position Q1 to form an electrostatic latent image on the surface of the image carrier PR. When forming a full-color image, K (black), Y
An electrostatic latent image corresponding to four color images (yellow), M (magenta), and C (cyan) is sequentially formed. In the case of a monochrome image, only an electrostatic latent image corresponding to a K (black) image is formed. Is done.

The rotary-type developing device G rotates K in the developing area Q2 sequentially with the rotation of the rotation shaft GA.
It has four color developing units GK, GY, GM and GC of (black), Y (yellow), M (magenta) and C (cyan).
Each of the developing units GK, GY, GM, and GC has a developing roll GR for transporting a developer to the developing area Q2.
The electrostatic latent image on the image carrier PR passing through the development area Q2 is developed into a toner image Tn.

Below the image carrier PR, a belt frame FB (indicated by a two-dot chain line) of a belt module BM slidable by a pair of left and right slide rails SR, SR is front and rear (in the X-axis direction and in the direction perpendicular to the paper surface). ) Is slidably supported. The belt module BM includes a plurality of belt support rolls (Rd, Rt, Rw, Rf, T2a) that rotatably support the intermediate transfer belt B, a primary transfer roll (primary transfer device) T1, and a contact. Roll T2
c and the belt frame FB that supports them. The plurality of belt support rolls (Rd, Rt, R
w, Rf, T2a) include a belt drive roll Rd, a tension roll Rt, a walking roll Rw, an idler roll (free roll) Rf, and a backup roll T2a, and the contact roll T2c is in contact with the backup roll T2a.

(Belt frame FB) Belt frame F
B is a front frame FBF (FIG. 4)
And a connecting frame (not shown) connecting the rear frame FBR (see FIG. 5) disposed at the rear and the rear frame FBR.
It consists of. In FIG. 4, the front frame FBF has a first front frame FBF1 and a second front frame FBF2 connected thereto, and the second front frame FBF2 has one transfer roll guide groove 1f and 2 A plurality of connecting pin insertion holes 2f, 2f are provided. The two connecting pin insertion holes F2f, 2f are arranged at positions on both left and right sides of the backup roll T2a and above the lower end of the backup roll T2a.

In FIG. 5, the rear frame FBR
Has a first rear frame FBR1 and a second rear frame FBR2 connected thereto, and the second rear frame FBR2 has one transfer roll guide groove 1r and two connection pin insertion holes 2r, 2r is provided. The two connecting pin insertion holes 2r, 2r are connected to the backup roll T2a.
And at a position below the lower end of the backup roll T2a. Therefore, when viewed from the front-back direction of the image forming apparatus main body U2, the four connecting pin insertion holes 2f, 2f, 2r, 2r are arranged so as to surround the lower end of the backup roll T2a.

2 and 3, in this embodiment, the pre-transfer sheet guide SG1 is a pre-transfer belt side sheet guide S.
G1a and the pre-transfer roll side sheet guide SG1b are configured separately, and as shown in FIGS. 4 and 5, the pre-transfer belt side sheet guide SG1a is supported by the second front frame FBF2 and the second rear frame FBR2. Have been. 4 and 5, the pre-transfer belt-side sheet guide SG1a is rotated about the hinge shaft 3a by the connecting levers 3, 3 (only one is shown) about the second front frame FBF2 and the second rear frame FBR2. Supported as possible. Further, a stopper 4 is provided on the second front frame FBF2 and the second rear frame FBR2, and regulates the rotation position of the connecting lever 3. The upstream end of the pre-transfer belt-side sheet guide SG1a is pulled upward by a tension spring 5.

In FIGS. 4 and 5, one end of a shaft 7 is connected to a bearing 6 which rotatably supports the primary transfer roll T1, and the shaft 7 is slid by a guide 8 fixed to a belt frame FB. Supported as possible. A plate 9 is fixed to the other end of the shaft 7, and the plate 9 is always subjected to a force in a direction away from the intermediate transfer belt B by a compression spring 10 disposed between the plate 9 and the guide 8.

An eccentric cam 11 is in contact with the plate 9, and the primary transfer roll T1 moves the intermediate transfer belt B to the image carrier P depending on the rotational position of the eccentric cam 11.
The intermediate transfer belt B is movable between a primary transfer position where the intermediate transfer belt B is pressed against R and a separation position where the intermediate transfer belt B is separated from the image carrier PR. The primary transfer area Q3 is formed by the pressure contact area between the intermediate transfer belt B and the image carrier PR. The rotational position of the eccentric cam 11 is determined by the belt frame F
B is rotated by a manual operation lever (not shown) provided on the front surface of B.

In FIG. 1, the primary transfer roll (primary transfer device) T1 is provided with a power supply circuit E controlled by a controller C.
As a result, a transfer voltage having a polarity opposite to the charge polarity of the toner is applied, and the toner image Tn on the surface of the image carrier PR is primarily transferred to the intermediate transfer belt B in the primary transfer area Q3. In the case of a full-color image, the toner images Tn of the respective colors sequentially formed on the surface of the image carrier PR are sequentially primary-transferred onto the surface of the intermediate transfer belt B in the primary transfer area Q3, and finally a full-color multiple toner An image is formed on the intermediate transfer belt B. When a monochromatic monocolor image is formed, only one developing unit is used, and the monochromatic toner image is primarily transferred onto the intermediate transfer belt B. After the primary transfer, the image carrier PR
The surface is cleaned of residual toner by the image carrier cleaner CLp. The charge is removed by the charge remover JR.

A slide frame FS disposed below the backup roll T2a is slidable back and forth (in a direction perpendicular to the paper surface) by a pair of left and right slide rails SR, SR, and is attached to and detached from the image forming apparatus main body. Supported as possible. The secondary transfer unit UT and the sheet transport belt BH are supported on the slide frame FS. 4 to 6, the slide frame FS
Is provided with a unit attaching / detaching portion 16 to which the secondary transfer unit UT is detachably attached. The unit attaching / detaching portion 16 has a unit lower fitting hole 16a, a positioning hole 1
6b and two screw holes 16c, 16c are formed.

(Secondary Transfer Unit UT) In FIG.
The secondary transfer unit UT includes a roll support lever LR rotatable about an axis LRa (see FIG. 6), a pre-transfer roll side sheet guide SG1b supported by the roll support lever LR, and secondary transfer rolls T2b and T2. Next transfer roll cleaner CLR (see FIG. 6) and the roll support lever LR
A tension spring 17 (see FIG.
6), an eccentric cam 18 for adjusting the rotational position of the roll support lever LR, and a post-transfer sheet guide SG2 (FIG. 6).
), And the secondary transfer unit frame FT that supports them. The secondary transfer unit frame FT has a front wall 19 of the secondary transfer unit, a rear wall 20 of the secondary transfer unit, and a connecting wall 21 connecting them. When the secondary transfer unit UT is mounted on the unit attaching / detaching portion 16, the lower portion of the connection wall 21 is fitted into the unit lower fitting hole 16a (see FIG. 6), and the lower surface of the secondary transfer unit rear wall 20 is provided. Positioning pin 20b
Are fitted into the positioning holes 16b (see FIG. 6). In this state, the secondary transfer unit UT is fixed to the unit attaching / detaching portion 16 using fixing screws 22 and 22 (see FIG. 6). The secondary transfer unit UT is fixed to the unit attaching / detaching portion 16 so as not to be movable in the X-axis direction, and is fixed with a play of about 1 mm in the Y-axis direction. Because of the play, the secondary transfer unit Ut is restricted in the vertical position only by the belt frame FB. Also, since there is play, when pulling out the secondary transfer unit Ut to the front side,
Space for preventing the intermediate transfer belt B from being damaged can be easily secured.

In FIG. 7, the secondary transfer unit front wall 19 is provided with a pair of connecting pins (unit front wall side connecting members) 19a, 19a protruding rearward (-X direction). The rear wall 20 of the secondary transfer unit is provided with a pair of connecting pins (unit rear wall side connecting members) 20a, 20a protruding rearward (-X direction). When the slide frame FS is moved to move the secondary transfer unit UT from a position where the secondary transfer unit UT is pulled out of the image forming apparatus (a position where the secondary transfer unit UT is drawn) to a mounting position (a position where the secondary transfer unit UT is inserted inside the image forming apparatus), The connecting pin 1 on the front wall 19 of the next transfer unit
9a and 19a are automatically inserted into the connection pin insertion holes (front frame side connection members) 2f and 2f (see FIG. 4) of the second front frame FBF2. At this time, the front frame FBF and the front wall 19 of the secondary transfer unit are automatically connected so that they cannot move vertically and horizontally relative to each other. Therefore, the connection pin insertion holes 2f, 2f and the connection pin 1
The front connecting members (2f, 2f, 19a, 1
9a) is configured.

Similarly, the rear connecting member (2) is formed by the connecting pin insertion holes 2r, 2r and the connecting pins 20a, 20a.
r, 2r, 20a, 20a), and when the secondary transfer unit UT is moved from the pull-out position to the mounting position, the connecting pins 2 of the rear wall 20 of the secondary transfer unit are moved.
0a, 20a are automatically inserted into the connecting pin insertion holes (rear frame side connecting members) 2r, 2r of the second rear frame FBR2, and the rear frame FBR and the rear wall 20 of the secondary transfer unit are automatically connected. It is connected so that it cannot move vertically and horizontally. Then, the front connecting member (2f, 2f, 19a,
19a) and rear connecting members (2r, 2r, 20a, 20).
a) The belt frame / secondary transfer unit automatic connection member (2f, 2f, 19a, 19a, 2r, 2r, 20a, 2)
0a) is configured.

In FIG. 6, the pair of front and rear roll support levers LR, LR (only one is shown) is a lever that supports the secondary transfer roll T2b and the secondary transfer roll cleaner CLR, and is a secondary transfer unit frame. FT secondary transfer unit front wall 19 and secondary transfer unit rear wall 20
, So as to be rotatable about the axis LRa.
In FIG. 7, an input gear G is provided at the rear end of an input gear shaft G1a rotatably supported by the rear wall 20 of the secondary transfer unit.
The input gear G1 meshes with a roll shaft gear G2 mounted on the shaft of the secondary transfer roll T2b. Therefore, when the input gear G1 rotates, the roll shaft gear G2 and the secondary transfer roll T2b rotate.

6 and 7, the eccentric cam 1 which comes into contact with a pair of front and rear roll support levers LR, LR, respectively.
8 and 18 are fixed to one cam shaft 18a, and the cam shaft 18a is connected to the front walls 19 and 2 of the secondary transfer unit.
It is rotatably supported by the rear wall 20 of the next transfer unit.
A gear G3 (see FIG. 7) is fixed to the camshaft 19a. Therefore, when the gear G3 rotates, the eccentric cams 18, 18 rotate, and the roll support levers LR, LR
Is designed to rotate. The eccentric cams 18, 18 and the roll support levers LR, LR move the secondary transfer roll T2b between a separated position distant from the intermediate transfer belt B and a secondary transfer position for pressing the intermediate transfer belt B against the intermediate transfer belt B. Secondary transfer roll moving device (18, 18, L
R, LR).

In FIG. 6, a secondary transfer area Q4 is formed by a contact area between the secondary transfer roll T2b and the intermediate transfer belt B, and a secondary transfer area Q4 is formed by the secondary transfer roll T2b, the backup roll T2a, and the control roll T2c. The next transfer unit T2 is configured. The pre-transfer roll side sheet guide SG1b fixed to the roll support lever LR
Is provided with a spacing member 23 for appropriately maintaining the spacing from the pre-transfer belt side sheet guide SG1a. In FIG. 6, the post-transfer sheet guide SG2
Is a guide for guiding the recording sheet S, which has passed the secondary transfer area Q4, to a sheet transport belt BH on the downstream side. The guide is rotatably supported on the axis of the secondary transfer roll T2b, and
It is pulled by a tension spring 24 and held at a position where it comes into contact with the projection 25.

In FIG. 1, the recording sheets S stored in the sheet feed tray TR1 are taken out by a pickup roll Rp at a predetermined timing, separated one by one by a separating roll Rs, and conveyed to a registration roll Rr. The recording sheet S conveyed to the registration roll Rr is transferred from the sheet guide SG1 before transfer to the secondary transfer area Q4 at the same time as the primary transferred multi-toner image or single-color toner image moves to the secondary transfer area Q4. It is transported to the area Q4. When the recording sheet S passes through the secondary transfer area Q4, the controller T2c of the secondary transfer unit T2 includes a controller C
A secondary transfer voltage having the same polarity as the charged polarity of the toner is applied from a power supply circuit E controlled by the power supply circuit E. The secondary transfer unit T2 collectively transfers the color toner image primary-transferred onto the intermediate transfer belt B to the recording sheet S in the secondary transfer area.
Is secondarily transferred. The residual toner is removed from the intermediate transfer belt B after the secondary transfer by the belt cleaner CLB. The toner adhered to the surface of the secondary transfer roll T2b is collected by a secondary transfer roll cleaner CLR.

The belt cleaner CLB is supported on the intermediate transfer belt B so as to be able to be freely separated (separated and contacted).
The belt cleaner CLB and the roll support lever L
The secondary transfer roller T2b supported by the intermediate transfer belt T2b, when a color image is formed, until the final unfixed toner image is primarily transferred to the intermediate transfer belt B.
Away from The secondary transfer roll cleaner CLR supported by the roll support lever LR moves together with the secondary transfer roll T2b. The recording sheet S on which the toner image has been secondarily transferred is a sheet guide S after transfer.
G2, the sheet is conveyed to the fixing area Q5 by the sheet conveying belt BH, and is heated and fixed by a fixing device F having a pair of fixing rolls composed of a heating roll Fh and a pressure roll Fp when passing through the fixing area Q5. The recording sheet S on which the toner image has been fixed is discharged to the recording sheet discharge tray TR2. The codes Rp, Rs, Rr, SG1, SG2, BH
The recording sheet conveying device SH is constituted by the elements indicated by.

(Operation of the Embodiment) The slide frame F
S is pulled out of the image forming apparatus main body U2,
The secondary transfer unit UT is mounted and fixed to the unit attaching / detaching portion 16. While the roll support lever LR is rotated so that the secondary transfer roll T2b is at a separated position (position separated from the intermediate transfer belt B), the slide frame FS on which the secondary transfer unit UT is mounted is It is inserted into the mounting position inside the image forming apparatus main body U2 from the extraction position. At this time, since the secondary transfer roll T2b is held at the standby position (position separated from the intermediate transfer belt B), the secondary transfer unit UT does not interfere with the belt module BM.

When the secondary transfer unit UT is moved to a mounting position (a position inserted into the back of the image forming apparatus main body U2), it is constituted by the connection pin insertion holes 2f, 2f and the connection pins 19a, 19a. Front connecting member (2f, 2
f, 19a, 19a) are automatically connected, and at the same time, the connecting pin insertion holes 2r, 2r and the connecting pins 20a, 2a.
0a, the rear connecting member (2r, 2r, 20a,
20a) is also automatically linked. At this time, the secondary transfer unit UT is connected to the belt frame F of the belt module BM.
B are automatically connected and fixed to each other. The input gear G1 and the gear G3 automatically mesh with a drive gear (not shown) provided in the image forming apparatus main body U2.

By transmitting a rotational force to the input gear G1, the secondary transfer roll T2b can be rotated. Further, by transmitting the rotational force to the gear G3, the eccentric cams 18, 18 are driven to rotate the roll support levers LR, LR, and the secondary transfer roll T2b is moved to the separated position (separated from the intermediate transfer belt B). Position and a secondary transfer position (a position where secondary transfer is performed by pressing against the intermediate transfer belt B).

In the state of FIG. 8A (the state in which the secondary transfer roll T2b is held at the secondary transfer position), the spacing member 23 of the roll-side sheet guide SG1b comes into contact with the lower surface of the belt-side sheet guide SG1a. I have. That is, the belt-side sheet guide SG1a is held at a predetermined distance from the roll-side sheet guide SG1b by the space holding member 23 of the roll-side sheet guide SG1b fixed to the roll support lever LR of the secondary transfer unit UT. At the same time, the positioning of the tip is performed.

As can be seen from the change in the positions of the belt-side sheet guide SG1a and the roll-side sheet guide SG1b when the state shown in FIG. 8A is shifted to the state shown in FIG. 8B, the roll support lever LR of the secondary transfer unit UT is moved to the separated position. The roll side sheet guide SG1b moves downward together with the roll support lever LR, and the belt side sheet guide SG
G1a is rotated clockwise around the hinge shaft 3a by the tension spring 5, and the pre-transfer roll side sheet guide SG1b is rotated.
Move away from 8B, the belt-side seat guide S
The rotation position of G1a is regulated by the stopper 4.

In the state of FIG. 8B, the slide frame F
After the secondary transfer roll T2b is pulled out of the image forming apparatus main body U2 together with S, the belt module BM can be pulled out of the image forming apparatus main body U2. In this embodiment, the front connecting member (2f, 2f, 19a, 19a) and the rear connecting member (2r, 2r, 20a, 20a) are used to automatically connect the belt frame / secondary transfer unit (2f, 2a).
f, 19a, 19a, 2r, 2r, 20a, 20a). The belt frame / secondary transfer unit automatic connection member (2f, 2f, 19a, 19a, 2r, 2
r, 20a, 20a), the belt modules BM and 2
The next transfer unit UT is directly connected. Therefore, 2
When the next transfer roll T2b is pressed against the intermediate transfer belt B,
Since the secondary transfer roll T2b and the intermediate transfer belt B do not separate from each other, it is possible to appropriately maintain the pressing force therebetween. Also, since the reaction force of the pressing force is absorbed between the secondary unit frame FT and the belt frame FB, the members of the image forming apparatus main body U2 supporting the secondary unit frame FT and the belt frame FB are not required. It does not bend or deform. Further, in the above-described embodiment, by pulling out the secondary transfer unit Ut to the front side, the jammed paper on the sheet conveying path can be easily removed.

(Modifications) Although the embodiments of the present invention have been described in detail, the present invention is not limited to the above-described embodiments, but falls within the scope of the present invention described in the appended claims. Thus, various changes can be made. Modified embodiments of the present invention will be exemplified below. (H01) The present invention is also applicable to an image forming apparatus using a transfer device using a corotron or the like instead of the primary or secondary transfer roll. (H02) Front frame FBF or rear frame F
Instead of providing the connecting pin insertion holes 2f, 2f or 2r, 2r in BR, connecting pins are provided, and connecting pins 19a, 19a or 20a, 20a are provided on the rear and front walls of the secondary transfer unit.
Instead of providing a pin connection hole, a pin connection hole can be provided.

(H03) The structure of the front frame FBF of the belt frame FB is such that the first front frame FBF1 is fixed to the slide rails SR, SR, and all the front frames FBF2 are fixed to the first front frame FBF1. It is possible to fix rolls. Note that the rear frame FBR can have the same configuration. (H04) The belt-side seat guide SG1a can be fixed to the belt frame FB instead of rotatably supporting it. The pre-transfer roll side sheet guide SG1B can be fixed to the secondary unit frame FT. In that case, the secondary transfer unit Ut can be arranged at an appropriate position by positioning with respect to the belt frame FB. (H05) As the configuration for pressing or separating the primary transfer roll with respect to the image carrier PR, various conventionally known configurations can be adopted.

(H07) The secondary transfer roll cleaner CLR can be fixed to another rotatable member without being fixed to the roll support lever LR. Then, according to the separation and contact of the secondary transfer roll T2b with respect to the intermediate transfer belt B,
The secondary transfer roll cleaner CLR can be configured to contact and separate from the secondary transfer roll T2b.

[0045]

The image forming apparatus of the present invention has the following advantages. (E01) By fixing the position of the secondary transfer device with respect to the intermediate transfer belt, the position of the secondary transfer area can be fixed. (E02) The pressing force between the secondary transfer roll and the intermediate transfer belt when the secondary transfer roll is used as the secondary transfer device can be appropriately maintained.

[Brief description of the drawings]

FIG. 1 is an overall explanatory diagram of one embodiment of an image forming apparatus of the present invention.

FIG. 2 is an enlarged view of a main part of FIG. 1;

FIG. 3 is a view of the same part as FIG. 2 but showing a different state.

FIG. 4 is an explanatory diagram of a front portion (front frame) of the belt frame.

FIG. 5 is an explanatory diagram of a rear portion (rear frame) of the belt frame.

FIG. 6 is an explanatory diagram of a support structure of a secondary transfer unit.

FIG. 7 is a perspective view of the secondary transfer unit as viewed from the rear side.

FIG. 8 is an explanatory diagram of a sheet guide on the upstream side of a secondary transfer area, and FIG. 8A is a view illustrating that a secondary transfer unit is in a secondary transfer position (2
FIG. 8B shows a state in which the secondary transfer unit is held at a position where the secondary transfer unit can be moved in and out of the intermediate transfer belt and can move in and out of the image forming apparatus main body. FIG.

[Brief description of reference numerals]

B: Intermediate transfer belt, BM: Belt module, FB ...
Belt frame, FBF: Front frame, FBR: Rear frame, PR: Photoconductor, Q3: Primary transfer area, Q4:
Secondary transfer area, Q5: fixing area, Rd: belt drive roll, S: recording sheet, SH: recording sheet transport device, T1 ...
Primary transfer unit, T2: Secondary transfer unit, T2b: Secondary transfer roll, UT: Secondary unit, 2f, 2f: Front frame side connecting member, 2r, 2r: Rear frame side connecting member, 1
9: front wall of the secondary transfer unit, 19a, 19a: connecting member on the front wall side of the unit, 20: rear wall of the secondary transfer unit, (Rt,
Rw, Rf, T2a) ... follower roll, (Rd, Rt, Rw, R
f, T2a): a plurality of belt supporting rolls, (2f, 2f, 1)
9a, 19a) ... front connecting member, (2r, 2r, 20a, 2)
0a) ... rear connecting member, (2f, 2f, 19a, 19a, 2)
r, 2r, 20a, 20a) ... Belt frame / secondary transfer unit automatic connection member.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masaru Ishikawa 2274 Hongo, Ebina-shi, Kanagawa Prefecture F-term within Fuji Xerox Co., Ltd. (Reference) 2H032 AA02 AA05 BA09 BA23 2H071 BA03 BA13 BA29 DA09 DA15

Claims (3)

[Claims] 1. An image forming apparatus having the following requirements (A01) to (A05): (A01) a photosensitive element in which a toner image is formed on a surface rotating and moving around a rotation axis extending in a front-rear direction. A body, (A02) a belt frame having a front frame and a rear frame disposed apart from each other;
A plurality of belt supporting rolls including a belt driving roll and a plurality of driven rolls supported at the front and rear end portions by the front frame and the rear frame, and the surface of the photosensitive member rotatably supported by the plurality of belt supporting rolls. An intermediate transfer belt rotatably moving through a primary transfer area where the toner image is transferred and a secondary transfer area where the primary transferred toner image is secondarily transferred to a recording sheet; and an intermediate transfer belt supported by the belt frame. Primary transfer of the toner image on the photoreceptor surface passing through the primary transfer area to an intermediate transfer belt 1
(A03) a recording sheet transport device for sequentially transporting the recording sheet to the secondary transfer area and the fixing area; and (A04) a drawer pulled out forward from a mounting position below the belt module. A secondary transfer unit supported to be movable back and forth between the
A secondary transfer unit including a rear wall of a next transfer unit, a front wall of a secondary transfer unit, and a secondary transfer unit that secondary-transfers a primary transfer toner image of an intermediate transfer belt passing through the secondary transfer area to the recording sheet. A transfer unit, (A05) a rear connecting member that automatically connects the rear wall of the secondary transfer unit and the rear frame so that they cannot move vertically and horizontally relative to each other when the secondary transfer unit is moved from the pull-out position to the mounting position; ,
A belt frame / secondary transfer unit automatic connecting member having a front connecting member that automatically connects the front wall of the secondary transfer unit and a front frame so that the front and rear frames cannot move relative to each other automatically; The rear connecting member formed by a unit rear wall connecting member provided on the rear transfer unit and a rear frame connecting member provided on the rear frame; a unit front wall connecting member provided on the front wall of the secondary transfer unit; The belt frame / secondary transfer unit automatic connection member having the front connection member constituted by a front frame side connection member provided on a frame. 2. The image forming apparatus according to claim 1, further comprising the following requirement (A06): (A06) a sheet conveying direction at a position below the intermediate transfer belt and in the secondary transfer area. The rear connection members provided on the upstream side and the downstream side, respectively, and the front connection members provided on the upstream side and the downstream side of the secondary transfer area in the sheet conveying direction at a position above the secondary transfer unit, respectively; The belt frame / secondary transfer unit automatic connection member having: 3. The image forming apparatus according to claim 1, wherein the following requirements (A07) and (A08) are provided.
(A07) the secondary transfer device constituted by a secondary transfer roll; (A08) a secondary transfer position at which the secondary transfer roll is separated from the intermediate transfer belt and pressed against the intermediate transfer belt; A secondary transfer roll moving device that moves by using.