JPH1173035A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To draw a belt module out of an image forming device without damaging a surface of an image carrier and a surface of an intermediate transferring belt, which contacts with the surface of the image carrier, each other. SOLUTION: In this device, primary transferring rolls 48, 49 are moved by a primary transferring roll moving device Im controlled by a moving device control device between a pressure-contact position that the primary transferring rolls 48, 49 push an intermediate transferring belt 47 from a back surface thereof at the time of primary transference so that a surface of the intermediate transferring belt 47 pressure-contacts with surfaces of image carriers D1, D2 and a separating position that the surface of the intermediate transferring belt 47 is separated from the surfaces of the image carriers D1, D2 at the time of the non-primary-transference, and in ordinary, the primary transferring rolls 48, 49 are held at the separating position. At belt module has the intermediate transferring belt 47, the primary transferring rolls 48, 49 and the primary transferring roll moving device Im and a module frame 41 for supporting them, and the belt module can be moved between a using position under the each image carrier D1, D2 and an outer drawing position drawn out of the device.

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 for transferring toner images formed on the surface of a plurality of image carriers onto a recording sheet via an intermediate transfer belt, and more particularly, to an image forming apparatus provided below each of the image carriers. The present invention relates to an image forming apparatus including a belt module configured to be movable in an axial direction of the image carrier between a use position and an external withdrawal position pulled out of the image forming apparatus.

[0002]

2. Description of the Related Art The following techniques are known as techniques of a tandem-type image forming apparatus in which a full-color image is formed by a plurality of image carriers on which an electrostatic latent image for each toner color is formed.

(J01) (Technology described in Japanese Patent Application Laid-Open No. 62-299873) This publication describes the following technique (a) as a prior art, and the following technique as an invention for solving the aforementioned prior art ( b) is described. (A) A technique of selectively operating only a backup member corresponding to a photosensitive drum on which a toner image to be transferred is formed, among a plurality of backup members for pressing a conveyor belt against a plurality of photosensitive drums. (B) In the above (a), the transfer contact force between the backup member and the photosensitive drum easily causes transfer unevenness and transfer failure at the time of image transfer. I have. That is, in a tandem-type image forming apparatus using a plurality of photosensitive drums (image carriers) on which a full-color image is formed, not only one photosensitive drum (image carrier) used during a single-color image forming operation, but also The other photosensitive drums (image carriers) are also rotated at the same time, and are conveyed while the surface of the recording sheet or the surface of the intermediate transfer belt is in contact with the surface of the photosensitive drum arranged downstream in the moving direction of the belt.

(J02) (Technique described in JP-A-6-175429) This publication discloses that a full-color image forming apparatus composed of a plurality of image carriers carries out an image forming operation during a single-color image forming operation. A technique is described in which a cleaning device or the like is separated from the surface of an image carrier that is not performed so that the surface of the image carrier is not worn.

[0005]

[Problems to be solved by the invention]

(Problem of (J01)) According to the technology (b) that solves the problem of the technology (a) of the (J01), a photosensitive drum (image carrier) that does not perform an image forming operation frequently uses a belt. Alternatively, there is a problem that the surface of the photosensitive drum is worn due to frictional contact due to frictional contact with the recording sheet, and the life is shortened. Further, when the belt, the transfer device, and a frame supporting the belt and the like are modularized so that maintenance can be easily performed, the module (belt module) is moved between a use position inside the image forming apparatus and an external pull-out position outside. The belt module must be kept out of contact with the photosensitive drum when moving between the photosensitive drums, and must be brought into contact with the photosensitive drum in the use position. Therefore, it is necessary to move the belt module below the photosensitive drum when moving the belt module, and to move the entire belt module up and down at the use position. However, there is a problem that such a configuration is complicated and large. Further, the contact device does not include the intermediate transfer belt and the sheet transport belt.

(Problem of (J02)) The prior art (J02) describes a technique for controlling the movement of a contact member such as a cleaning device that comes into contact with the surface of each image carrier during an image forming operation. However, no consideration is given to the wear of the image carrier and the belt due to frictional contact, and the case where the belt or the like is modularized for maintenance.

In view of the above circumstances, the present invention relates to an image forming apparatus using a belt module having an intermediate transfer belt or a sheet conveying belt that moves in contact with a plurality of image carriers, and provides the following (O01), (O02) ) Is the subject of the description. (O01) When the belt module is moved between a use position inside the image forming apparatus and an external pull-out position outside, the belt module is prevented from contacting the photosensitive drum, and can be easily pressed or separated at the use position. To be. (O02) To reduce wear due to contact friction between the image carrier and the intermediate transfer belt or the sheet transport belt.

[0008]

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 correspondence 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.

(1st invention) In order to solve the aforementioned problem,
The image forming apparatus according to the first aspect of the present invention has the following requirements. (A01) Rotating shafts extending in the horizontal direction are arranged in parallel with each other, and rotate around the rotating shaft. A plurality of image carriers (D1, D2) on which an electrostatic latent image is formed on an endless surface; (A02) each of the image carriers (D1, D2)
2) Developing devices (Gy, Gm, Gc, Gk) for developing the electrostatic latent images on the surface into toner images, respectively (A03) Primary devices set along the surface of each image carrier (D1, D2) An intermediate transfer belt (47) rotatably moving through transfer areas (Q1, Q2); (A04) pressing the intermediate transfer belt (47) in each of the primary transfer areas (Q1, Q2) to form the image carrier; (D1, D2) a pressure contact position for pressing against the surface and a surface where the surface of the intermediate transfer belt (47) is separated from the surface of the image bearing member (D1, D2) so as to be movable. The plurality of image carriers (D1,
D2) A plurality of primary transfer rolls (48, 4) for transferring the toner image on the surface to the intermediate transfer belt (47), respectively.
9), (A05) The recording sheet (S) is placed in the secondary transfer area (Q3) set in the movement path of the intermediate transfer belt (47).
Sheet transport device (76-79 +
82 + 83), (A06) a secondary transfer unit (44 + 7) which is arranged in the secondary transfer area (Q3) and transfers the toner image on the intermediate transfer belt (47) to the recording sheet (S).
4), (A07) the plurality of primary transfer rolls (48, 4
9) a primary transfer roll moving device (Im) for independently moving the pressure transfer position between the press contact position and the separated position and always holding the separated transfer position at the separated position; Im) by controlling the operation of the primary transfer rolls (48, 49) to the corresponding image carriers (D1, D1).
D2) a moving device controller (Ic) for moving to the pressing position during the image forming operation and to the separating position during non-image forming, (A09) the intermediate transfer belt (47), and the respective primary transfer rolls (48) , 49), the primary transfer roll moving device (Im) and the module frame (41) for supporting the same, and each of the image carriers (D
1, D2) A belt module (B) movable in the axial direction of the image carrier (D1, D2) between a lower use position and an external withdrawal position that is pulled out of the apparatus. The moving device controller (Ic) moves the primary transfer rolls (48, 49) to the separated position at the end of the primary transfer at the end of image formation or to the separated position at the end of the secondary transfer. .

(Operation of the First Invention) In the image forming apparatus according to the first invention of the present application having the above-mentioned features, the plurality of image carriers (D1, D2) have their horizontally extending rotation axes parallel to each other. The electrostatic latent images are formed on the endless surfaces of the plurality of image carriers (D1, D2). Developing device (G
y, Gm, Gc, Gk) develop the electrostatic latent images on the surfaces of the respective image carriers (D1, D2) into toner images. The endless surface of the intermediate transfer belt (47) rotates through the primary transfer areas (Q1, Q2) respectively set along the surfaces of the image carriers (D1, D2).

In each of the primary transfer areas (Q1, Q2), a plurality of primary transfer rolls (48, 49) press the intermediate transfer belt (47) to form the image carriers (D1, D2). The intermediate transfer belt (47) is movably disposed between a pressing position where the surface is pressed against the surface and a separation position where the surface of the intermediate transfer belt (47) is separated from the surfaces of the image carriers (D1 and D2). The primary transfer roll moving device (Im) includes a plurality of primary transfer rolls (48, 4).
9) is independently moved between the pressure contact position and the separation position, and is always held at the separation position. A moving device control device (Ic) controls the operation of each of the primary transfer roll moving devices (Im) to move each of the primary transfer rolls (48, 49) to a corresponding one of the image carriers (D1, D2). During the image forming operation, the image forming apparatus is moved to the pressure contact position, and is moved to the separated position during non-image forming. The plurality of primary transfer rolls (48, 49) transfer the toner images on the surfaces of the plurality of image carriers (D1, D2) to the intermediate transfer belt (47) at the pressure contact position. The recording sheet conveying device (76 to 79 + 82 + 83) is provided with a secondary transfer area (Q3) set on the movement path of the intermediate transfer belt (47).
The recording sheet (S) is conveyed and passed therethrough. Secondary transfer unit (44 + 74) arranged in the secondary transfer area (Q3)
Transfers the toner image on the intermediate transfer belt (47) to the recording sheet (S).

A belt module (B) having the intermediate transfer belt (47), the respective primary transfer rolls (48, 49), the primary transfer roll moving device (Im), and a module frame (41) supporting the same; Is movable in the axial direction of the image carriers (D1, D2) between a use position below each of the image carriers (D1, D2) and an external pull-out position pulled out of the apparatus. In a state where the primary transfer rolls (48, 49) are held at the separated positions by the primary transfer roll moving device (Im), the belt module (B)
The intermediate transfer belt (47) of the image bearing member (D1, D
2) is kept away from In this state, the belt module (B) can be moved between the use position and the external pull-out position pulled out of the apparatus. In this case, abrasion or damage due to frictional contact between the intermediate transfer belt (47) and the image carriers (D1, D2) can be prevented. The maintenance of the belt module (B) can be easily performed at the external pull-out position. Further, at the use position of the belt module (B) (position mounted inside the image forming apparatus), the primary transfer roll (48, 49) can be moved to the separation position and the pressure contact position. Then, the primary transfer operation by the primary transfer rolls (48, 49) can be performed in a state where the primary transfer roll (48) is moved to the pressing position.

During non-image formation of the image carriers (D1, D2) corresponding to the respective primary transfer rolls (48, 49), the intermediate transfer belt (47) and the surfaces of the image carriers (D1, D2) Are separated, the intermediate transfer belt (47)
Even when is rotated, the surface of the intermediate transfer belt (47) and the surface of the image bearing members (D1, D2) do not come into frictional contact. For this reason, damage due to abrasion of the surface of the intermediate transfer belt (47) or the surface of the image bearing members (D1, D2) is small, and the life is extended.

(Second invention) In order to solve the above problems,
(B01) The image forming apparatus according to the second aspect of the present invention has the following requirements. (B01) The rotating shafts extending in the horizontal direction are arranged in parallel with each other, and rotate around the rotating shaft. A plurality of image carriers (Dy, Dm, Dc, Dk) on which an electrostatic latent image is formed on an endless surface; (B02) an electrostatic latent surface on each of the image carriers (Dy, Dm, Dc, Dk) Developing units (Gy, Gm, Gc, Gk) for developing the respective images into toner images, (B0
3) Transfer areas (Qy, Qm, Qc, Qk) set along the surface of each of the image carriers (Dy, Dm, Dc, Dk)
And a sheet conveying belt (103) for conveying and passing the recording sheet (S) through the transfer areas (Qy, Qm,
Qc, Qk), the pressing position where the sheet conveying belt (103) is pressed and pressed against the surface of the image carrier (Dy, Dm, Dc, Dk) and the surface of the sheet conveying belt (103) are the image carrier ( Dy, Dm, Dc, Dk) The plurality of image carriers (Dy, Dm, Dc, Dk) are movably disposed between the recording sheet (S) at the pressing position and the separated positions away from the surface. A) a plurality of transfer rolls (104y to 104k) for respectively transferring the toner image on the surface;
(B05) a transfer roll moving device (Im) for independently moving each of the transfer rolls (104y to 104k) between the pressure contact position and the separation position and always holding the transfer roll at the separation position; Transfer roll moving device (Im)
Of the transfer rolls (104y-104)
a moving device control device (Ic) for moving k) to the press-contact position during image formation of the corresponding image carrier (Dy, Dm, Dc, Dk), and to the separation position during non-image formation;
(B07) The sheet carrier belt (103), the transfer rolls (104y to 104k), the transfer roll moving device (Im), and the module frame (41) for supporting these, and the image carriers (Dy, Dm) ,
Dc, Dk) The image carriers (Dy, Dm, Dc, Dk) between a use position below and an external pull-out position pulled out of the apparatus.
A belt module (B) that can move in the axial direction.

(Function of the Second Invention) In the image forming apparatus of the second invention of the present application having the above-described features, the horizontally extending rotary shaft of the plurality of image carriers (Dy, Dm, Dc, Dk) is provided. Are arranged in parallel with each other, and the plurality of image carriers (D
An electrostatic latent image is formed on each of the endless surfaces that rotate around the rotation axes y, Dm, Dc, and Dk). Developing device (Gy,
Gm, Gc, Gk) are the respective image carriers (Dy, Dm, Dc, D
k) Develop each electrostatic latent image on the surface into a toner image. Each of the plurality of transfer rolls (104y to 104k) presses the sheet transport belt (103) in each of the transfer areas (Qy, Qm, Qc, Qk), and the image carriers (Dy, Dm, D).
c, Dk) The pressing position to press against the surface and the surface of the sheet conveying belt (103) are the image carrier (Dy, Dm, Dc,
Dk) It is movably arranged between a remote position away from the surface. The transfer roll moving device (Im) moves each of the transfer rolls (104y to 104k) independently between the pressed position and the separated position, and always keeps the transfer roll at the separated position.

A moving device control device (Ic) controls the operation of the transfer roll moving device (Im) so that each of the transfer rolls (104y to 104k) is associated with a corresponding image carrier (Dy, Dy,
Dm, Dc, and Dk) are moved to the pressure contact position during image formation, and are moved to the separation position during non-image formation. When forming images on the corresponding image carriers (Dy, Dm, Dc, Dk), the primary transfer rolls (104y to 104y to
4k) presses the sheet conveying belt (103) against the surface of the image carrier (Dy, Dm, Dc, Dk). Then, the primary transfer roll (104y to 104k) at the pressing position
Is a recording sheet (S) in which the toner image on the surface of the image carrier (Dy, Dm, Dc, Dk) is conveyed by the sheet conveying belt (103) in each of the transfer areas (Qy, Qm, Qc, Qk). Transfer to each.

Corresponding image carriers (Dy, Dm, Dc, Dk)
Is the transfer roll (104y to 104k) during non-image formation.
Moves to the separation position, so that the sheet conveying belt (103) separates from the image carriers (Dy, Dm, Dc, Dk). In this state, the belt module (B) can be moved between the use position (position mounted inside the image forming apparatus) and the external pull-out position pulled out of the apparatus. In this case, the sheet transport belt (10
3) Wear and damage due to frictional contact between the image bearing members (Dy, Dm, Dc, Dk) can be prevented. The maintenance of the belt module (B) can be easily performed at the external pull-out position.

Even if the sheet transport belt (103) and each image carrier (Dy, Dm, Dc, Dk) are rotating, the sheet transport belt (103) is kept in contact with each image carrier except during image formation. (Dy, Dm, Dc, Dk) No contact with the surface,
Since the contact friction time between the two surfaces is short, the surface of the sheet conveying belt (103) or each of the image carriers (D
(y, Dm, Dc, Dk) Less damage due to surface wear and longer life.

(Third invention) In order to solve the above problems,
(C01) The image forming apparatus according to the third aspect of the present invention has the following requirements. (C01) Rotating shafts extending in the horizontal direction are arranged in parallel with each other, and rotate around the rotating shaft. A plurality of image carriers (D1, D2) on which an electrostatic latent image is formed on an endless surface; (C02) each of the image carriers (D1, D2)
2) developing units (Gy, Gm, Gc, Gk) for developing the electrostatic latent images on the surfaces into toner images, respectively; (C03) primary units set along the surfaces of the image carriers (D1, D2), respectively. The intermediate transfer belt (47) rotating and moving through the transfer areas (Q1, Q2), (C04) the toner image on the surface of the image carrier (D1, D2) in each of the primary transfer areas (Q1, Q2). Primary transfer units (48 ', 49') for transferring to the intermediate transfer belt (47), respectively (C05) the intermediate transfer belt (4
7) a recording sheet conveying device (76 to 79 + 82 + 83) for conveying and passing the recording sheet (S) to the secondary transfer area (Q3) set in the movement path of (7), (C06) disposed in the secondary transfer area (Q3) Then, a secondary transfer unit (44 + 74) for transferring the toner image on the intermediate transfer belt (47) to the recording sheet (S), (C07) the image carriers (D1, D2)
And a press-contact position for pressing the intermediate transfer belt (47) against the surface of the image bearing member (D1, D2) and the intermediate transfer belt. (47) The surface is the image carrier (D1, D2)
A plurality of belt press-contact rolls (108), each of which is movable between a separation position separated from the surface, and (C08) each of the belt press-contact rolls (108) independently between the press-contact position and the separation position; A press-contact roll moving device (Im ') that moves and always holds the separated position.
(C09) The operation of the pressing roll moving device (Im ') is controlled to move each of the belt pressing rolls (108) to the pressing position during the image forming operation of the corresponding image carrier (D1, D2). (C010) The intermediate transfer belt (47), the primary transfer units (48 ', 49'), the belt pressure roller (108), and the pressure roller. It has a moving device (Im ') and a module frame (41) for supporting them, and each of the image carriers (D1, D2)
A belt module (B) movable in the axial direction of the image carrier (D1, D2) between a lower use position and an external draw-out position pulled out of the apparatus.

In the third invention, a corotron or a primary transfer roll can be used as the primary transfer device. Then, the intermediate transfer belt (47) is pressed by a belt pressing roller (108) to be pressed against the surface of the image carrier (D1, D2) or the surface of the intermediate transfer belt (47) is brought into contact with the image carrier (D1, D2). ) When separating the roller from the surface, the corotron and the primary transfer roll are simultaneously moved with the belt pressing roller (108), or the corotron is stopped and the belt pressing roller (10) is stopped.
8) It is possible to configure to move only.

(Operation of the Third Invention) In the image forming apparatus of the third invention of the present application having the above-mentioned features, the intermediate transfer belt (47) is pressed to contact the surface of the image carrier (D1, D2). When the primary transfer unit is a primary transfer roll, the primary transfer roll is moved to the pressure contact position or the separation position simultaneously with the movement of the belt pressure contact roll (108). When the primary transfer unit is a corotron, the belt pressing roller (108) is moved at the same time as the belt pressing roller (108) is moved, or the corotron is moved to a pressing position or a separated position, or the corotron is stopped and the belt pressing roller (10) is stopped.
Move 8). Another operation of the third invention is the first operation.
This is the same as the operation of the invention.

(Fourth invention) In order to solve the above problems,
(D01) The image forming apparatus according to the fourth aspect of the present invention has the following requirements. (D01) Rotating shafts extending in the horizontal direction are arranged in parallel with each other, and rotate around the rotating shaft. A plurality of image carriers (Dy, Dm, Dc, Dk) on which an electrostatic latent image is formed on an endless surface; (D02) an electrostatic latent surface on each of the image carriers (Dy, Dm, Dc, Dk) Developing units (Gy, Gm, Gc, Gk) for developing the respective images into toner images, (D0
3) Transfer areas (Qy, Qm, Qc, Qk) set along the surface of each of the image carriers (Dy, Dm, Dc, Dk)
Conveyor belt (103), which conveys and passes the recording sheet (S) through (D04), the image carriers (Dy, Dm,
Dc, Dk) The image bearing members (Dy, Dm, Dc, Dc, Dk) are formed on a recording sheet (S) passing through transfer areas (Qy, Qm, Qc, Qk) on the surface.
Dk) Transfer devices (10) for transferring toner images on the surface, respectively.
4y to 104k, 104y 'to 104k'), (D05) The sheet transporting means is disposed on the back side of the sheet transporting belt (103) in correspondence with the image carriers (Dy, Dm, Dc, Dk). By pressing the belt (103), the image carrier (D
y, Dm, Dc, and Dk) and the surface of the sheet conveying belt (103) that is pressed against the surface of the image carrier (Dy,
Dm, Dc, Dk) a plurality of respective belt press-contact rolls (108) movable respectively to and from a separation position away from the surface;
(D06) a press-contact roll moving device (Im ″) that moves each of the belt press-contact rolls (108) independently between the press-contact position and the separation position and always holds the belt press-contact roll (108) at the separation position; Press roll moving device (Im ")
The belt pressing roller (108) is controlled by controlling the operation of
A moving device control device for moving the image carrier (Dy, Dm, Dc, Dk) to the press-contact position during image formation and to the separation position during non-image formation corresponding to each of the image carriers (Dy, Dm, Dc, Dk); (103), the transfer device (104y ~
104k, 104y 'to 104k'), the belt pressure roller (108), the pressure roller moving device (Im "), and a module frame (41) for supporting them, and each of the image carriers (Dy, Dm, Dc). Dk) a belt module (B) movable in the axial direction of the image carrier (Dy, Dm, Dc, Dk) between a lower use position and an external draw-out position pulled out of the apparatus.

In the fourth invention, a corotron or a transfer roll can be used as the transfer device. Then, the sheet conveying belt (103) is pressed by a belt pressure roller (108) to press the image carrier (D).
y, Dm, Dc, Dk) or the surface of the sheet conveying belt (103) is pressed against the image carrier (Dy, Dm, Dk).
c, Dk) When detaching from the surface, the corotron and the transfer roll are moved simultaneously with the belt pressing roller (108), or the corotron is stopped and only the belt pressing roller (108) is moved. It is possible.

(Operation of the Fourth Invention) In the image forming apparatus of the fourth invention of the present application having the above-described features, the image carrier (Dy, Dm, D) is pressed by pressing the sheet conveying belt (108).
c, Dk) or the image carrier (Dy, Dm, Dc, Dk), when the transfer unit is a transfer roll, when the transfer unit is a transfer roll, the transfer roll is moved simultaneously with the movement of the belt pressing roll (108). Move to the pressure contact position or remote position. When the transfer device is a corotron, the corotron is moved to the press-contact position or the separation position simultaneously with the movement of the belt press roller (108), or the belt press roller (108) is moved while the corotron is stationary. Other functions of the fourth invention are the same as those of the second invention.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION

Next, examples (embodiments) of the embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments. In order to facilitate understanding of the following description, orthogonal coordinate axes X, Y, and Z are defined in directions of arrows X, Y, and Z orthogonal to each other in the drawings, and the arrow X direction is forward, and the arrow Y is arrow Y. The direction is leftward and the arrow Z direction is upward. In this case, the direction opposite to the X direction (front) (−X direction) is backward, the direction opposite to the Y direction (left) (−Y direction) is right, and the direction Z (upward) is opposite (−Z direction). Is below. In addition, front (X direction) and rear (-X direction)
, Including the front-back direction or the X-axis direction, to the left (Y direction)
And the right or left (-Y direction), or the Y-axis direction, and the upward or downward (-Z direction) or the vertical or Z-axis direction. In the figure,
The one with "•" in "O" means an arrow heading from the back of the paper to the front, and the one with "X" in "O" means an arrow pointing from the front to the back of the paper. Shall mean.

Embodiment 1 FIG. 1 is an overall explanatory view of an image forming apparatus according to Embodiment 1 of the present invention. FIG. 2 is an enlarged view of a main part on the left side (Y direction side) of the image forming apparatus shown in FIG. FIG. 3 is a perspective view of the belt module. FIG.
FIG. 4A is an explanatory diagram of the positional relationship between the next transfer roll and the intermediate transfer belt and the image carrier, and FIG.
FIG. 4 is a diagram illustrating a position of a primary transfer roll in a state where an intermediate transfer member and an image carrier are in contact with each other. FIG.
FIG. 5A is a detailed explanatory diagram of the next transfer roll position adjusting device, FIG. 5A is a detailed explanatory diagram viewed from the direction shown in FIG. 2, and FIG.
5C is a sectional view taken along line VB-VB, and FIG. 5C is a sectional view taken along line VC-VC in FIG. 5A. FIG. 6 is a block diagram of the first embodiment.

In FIG. 1, an image forming apparatus U has a digital copying machine U1 as a main body of the image forming apparatus having a platen glass (transparent document table) A1 on an upper surface, and is detachably mounted on the platen glass A1. The automatic document feeder U2 is provided. The automatic document feeder U2 is adapted to copy documents Gi (i = 1, 2, 2, 3) of various sizes to be copied.
..) Are placed on top of each other. The document placed on the document feed tray TRk is transported to a copy position on the platen glass A1, and the copied document Gi is discharged to the document discharge tray TRh.

The copying machine U1 has a UI (user interface), an image input terminal IIT (hereinafter, referred to as IIT) as an image reading section and an image as an image recording operation section which are sequentially arranged below the platen glass A1. Output Terminal IOT (I
OT) and an IP provided between the IIT and the IOT.
S (image processing system).

The UI is a part where the user inputs an operation command signal such as copy start and the like, and has a display section, a copy start button, a copy set number input key and the like. The display section displays information relating to the current setting state of the image forming apparatus U. An IIT as an original reading device disposed below the transparent platen glass A1 on the upper surface of the copying machine main body U1 includes an exposure system registration sensor (platen registration sensor) Sp and an exposure optical system 1 arranged at a platen registration position (OPT position). have. The exposure optical system 1 has a movable lamp unit 2, and the lamp unit 2 is configured by integrating a lamp 3 for illuminating a document and a first mirror 4. Further, the exposure optical system 1 has a movable mirror unit 5 that moves at half the speed of the lamp unit 2. This moving mirror unit 5
Is composed of a second mirror 6 and a third mirror 7.

Then, the lamp unit 2 moves in the left-right direction (Y-axis direction) in FIG. 1 in parallel with the original, and the moving mirror unit 5 moves at half the moving speed of the lamp unit 2. When the document Gi is moved by a distance of 1/2, the distance between the document Gi and the lens 8 is kept constant, and during that time, the reflected light of the document Gi illuminated by the lamp 3 passes through the exposure optical system 1. And is converged on a CCD (solid-state image sensor). The CCD
Has a function of converting the original reflected light converged on the imaging surface into an electric signal.

The IPS has image read data output means 11 for adjusting the gain of an analog electric signal of a read image obtained by the IIT CCD, converting the analog signal into a digital signal, performing shading correction and the like, and outputting the digital signal. ing. The IPS has a write image data output unit 12 to which the image read data output from the image read data output unit 11 is input, and the write image data output unit 12 temporarily stores the image data. It has an image memory 13 to be used. The write image data output unit 12 has a function of performing data processing such as density correction and enlargement / reduction correction on the input image read data and outputting the image read data to the IOT as write image data (laser drive data). ing.

The IPS write image data output means 12
The laser drive signal output unit 14 of the IOT to which the image write data (laser drive data) output by the IOT is input is a laser drive signal corresponding to the input image data, which is output by the optical write scanning device (that is, the latent image forming device). ) Output to ROS1 and ROS2. Since ROS1 and ROS2 have the same configuration,
The configuration of ROS1 will be described. ROS1 has mirrors 21, 22, 23. A laser oscillator (not shown) is arranged behind the mirror 21 (in FIG. 1, in a direction perpendicular to the plane of FIG. 1 and on the back side of the plane of FIG. 1).
The laser beam is modulated in accordance with the input signal from the laser light source 4 and emits a laser beam L1 for image writing. The laser beam L1 is incident on the mirror 21 from the back side of the plane of FIG. The laser beam L1 reflected by the mirror 21 is sequentially reflected by the mirrors 22 and 23, and converges on the reflection surface of the polygon mirror 25 through the fθ lens 24.

The laser light L1 converged and reflected by the polygon mirror 25 passes through the fθ lens 24 again, passes through the mirrors 23 and 22, and enters the mirror 26. The laser beam L1 reflected by the mirror 26 is applied to the cylindrical mirror 2
The light is reflected on the image carrier 7 and converges on the image carrier D1 of the toner image forming apparatus T1. The ROS2 is the RO
The configuration is the same as that of S1, and the laser beam L2 of ROS2 is configured to converge on the image carrier D2 of the toner image forming apparatus T2. Note that the toner image forming apparatus T1 is Y
(Yellow) and M (magenta) toner images, and the toner image forming device T2 is a device for forming C (cyan) and K (black) toner images.

When a toner image of Y (yellow) is formed by the toner image forming apparatus T1, the laser drive signal output device 14 outputs Y (yellow) to ROS1.
Y (yellow) image data for image formation is input, and M
When a (magenta) toner image is formed, M (magenta) image data for forming an M (magenta) image is input from the laser drive signal output device 14 to ROS1. When a C (cyan) toner image is formed by the toner image forming apparatus T2, the laser drive signal output device 14 outputs C (cyan) to the ROS2.
C (cyan) image data for image formation is input, and K
When forming a (black) toner image, the laser drive signal output device 14 sends a K (black) image forming K
It is configured to input (black) image data.

The toner image forming apparatus T1 includes an image carrier (YM image carrier) D1 which is driven to rotate, and a charger 3 which is sequentially arranged along the rotation direction of the YM image carrier D1.
1, a Y (yellow) developing unit Gy, an M (magenta) developing unit Gm, a static eliminator 32, and a cleaner 33. Also,
The toner image forming apparatus T1 includes the Y (yellow) developing device Gy.
And a M (magenta) developer transport pipe Pm for transporting the developer to the M (magenta) developer Gm. The components of the toner image forming apparatus T1 are supported by a housing H1, and the housing H1 is supported by a slide rail R1 so as to be slidable in the front-rear direction (the direction perpendicular to the paper surface, the X-axis direction).

The toner image forming apparatus T2 comprises an image carrier (CK image carrier) D2 which is driven to rotate, and a charger 3 which is sequentially arranged along the rotation direction of the CK image carrier D2.
1, a C (cyan) developing unit Gc, a Y (black) developing unit Gk, a static eliminator 32, and a cleaner 33. Further, the toner image forming apparatus T2 is for transporting the developer to the C (cyan) developer Gc and the C (cyan) developer transport pipe Pc for transporting the developer to the C (cyan) developer Gc. K
(Black) Has a developer transport pipe Pk. The respective components of the toner image forming apparatus T2 are supported by a housing H2, and the housing H2 is supported by a slide rail R2 so as to be slidable in a front-rear direction (a direction perpendicular to the paper surface, an X-axis direction). The image carriers D1, D2
The YM image carrier rotation speed Sd1
Rotation speed sensors Sd1 and Sd2 for measuring the rotation speed Sd2a of the image carrier for a and CK are arranged.

To the left (-Y direction) of the ROS1 and the toner image forming apparatus T1, a developer storage container Vy for storing a Y (yellow) developer and a developer storage container Vm for storing an M (magenta) developer. Is arranged. The Y developer stored in the developer storage container Vy is transported by a developer supply pipe Vyp extending obliquely downward, and the developer transport pipe P
The developing device Gy is supplied to the developing device Gy through y. The developer supply pipe Vyp and the developer transport pipe Py are disposed at the rear end side (−X direction side) of the image forming apparatus, and the connection between the two pipes Vyp and Py connects the toner image forming apparatus T1 to It is configured to be connected while being inserted from the front to the rear along the slide rail R1. The M developer stored in the developer storage container Vm is transported by a developer supply pipe Vmp extending rightward (Y direction), and is supplied to the developing device Gm through the developer transport pipe Pm. Have been. The developer supply pipe Vmp and the developer transport pipe Pm are disposed at a rear end portion of the image forming apparatus.
The connection between Pm and Pm is configured such that the toner image forming device T1 is connected from the front to the rear along the slide rail R1.

To the right (Y direction) of the ROS2 and the toner image forming apparatus T2, there are a developer storage container Vc for storing C (cyan) developer and a developer storage container Vk for storing K (black) developer. Are located. The C developer stored in the developer storage container Vc is transported by a developer supply pipe Vcp extending obliquely downward, and is supplied to the developing device Gc through the developer transport pipe Pc. The developer supply pipe Vcp and the developer transport pipe Pc are disposed at a rear end portion of the image forming apparatus, and the connection between the two pipes Vcp and Pc connects the toner image forming apparatus T2 along the slide rail R2. It is configured to be connected while being inserted from the front to the rear.

The K developer contained in the developer storage container Vk is transported by a developer supply pipe Vkp extending to the left (-Y direction), and is supplied to the developing device Gk through the developer transport pipe Pk. It is configured to: The developer supply pipe Vkp and the developer transport pipe Pk are arranged at the rear end of the image forming apparatus.
The connection of kp and Pk is configured such that the toner image forming device T2 is connected in a state of being inserted from the front to the rear along the slide rail R2.

In FIGS. 1 and 3, the image carriers D1, D2
A belt module B is disposed below the belt module. Belt module B consists of front frame 41F and rear frame 4
1B, a left-side frame 41L, and a right-side frame 41R. A rail R3 is disposed on each outer surface of the left frame 41L and the right frame 41R of the module frame 41, and the module frame 41 is moved in the front-rear direction (X-axis direction) in the image forming apparatus U by the rail R3. It is configured to be slidable. The front frame 41
A grip portion 41H on the F side for facilitating the user to slide the module frame 41 in the front-rear direction.
Are formed. Inside the module frame 41, a belt supporting frame 41v is integrally formed with the left frame 41L in the front and rear directions. Both ends of each shaft of a drive roll 42, a tension roll 43, and a backup roll for secondary transfer 44 are rotatably supported by the two belt supporting frames 41v. A belt cleaner 46 is disposed between the tension roll 43 and the right frame 41R, and both ends of the belt cleaner 46 are supported by the front frame 41F and the rear frame 41B. A rotation drive mechanism (not shown) of the drive roll 42, the tension roll 43, and the backup roll 44 for the secondary transfer is provided between the belt support frame 41v on the rear side and the front frame 41F and the rear frame 41B of the module frame 41. Is arranged.

The drive roll 42 and the tension roll 4
The intermediate transfer belt 47 is rotatably supported by the third and second transfer backup rolls 44. A primary transfer roll 4 whose vertical position can be adjusted is located at a position facing the image carriers D1 and D2 with the intermediate transfer belt 47 interposed therebetween.
8, 49 are arranged. A rotation speed sensor Sv (see FIG. 2) for measuring the rotation speed Sva of the intermediate transfer belt is arranged at an end in the width direction of the intermediate transfer belt 47. The primary transfer roll (primary transfer roll for YM)
48 and primary transfer roll (primary transfer roll for CK) 4
Primary transfer areas Q1, Q2 are formed between the surface of the intermediate transfer belt 47 with which the belt 9 contacts and the image carriers D1, D2. The primary transfer areas Q1 and Q2 correspond to the image carriers D1 and D2.
This is an area where the upper toner image is transferred onto the intermediate transfer belt 47.

In FIG. 5, the primary transfer roll 49 that moves in the contact / separation direction (the direction of movement between the pressure contact position and the separation position) between the pressure contact position (two-dot chain line) and the separation position (solid line) has a rotating shaft 49b. And a roll 49a having The rotation shaft 49b is rotatably supported by a bearing 51, and the bearing 51 is supported by a cylindrical roll support member S2 extending in the contacting / separating direction (moving direction). The roll support member S2 is provided with the roll 49a.
A cam contact surface S2a is provided at the end that does not support the roller, and a guided member S2b extending in the contact and separation direction is fixed to the outer peripheral surface of the roll support member S2.

On the outer peripheral side of the roll support member S2, a support member guide 52 supports the roll support member S2 so as to be movable in the contact and separation directions. A guide groove 52a is formed on the inner peripheral surface of the support member guide 52, and slidably engages with the guided member S2b of the roll support member S2 to guide the roll support member S2 in a separating / contacting direction. It is supposed to. An eccentric cam 53 is arranged to contact the cam contact surface S2a of the roll support member S2.
The eccentric cam 53 is supported by a cam rotation shaft 54,
The cam rotation shaft 54 is rotatably supported by bearings 56. A pulley 57 is supported at one end of the cam rotation shaft 54, and the pulley 57 has a CK
The rotational force of the motor-side pulley 58 attached to the output shaft of the motor M2 is transmitted via a belt 59. Therefore, when the pulley 57 is rotated by the CK roll moving motor M2, the eccentric cam 53 is also rotated, and the roll supporting member S2 that contacts the eccentric cam 53 is moved. When the roll 49a supported by the roll supporting member S2 moves from the pressing position to the separated position, the roll 49a presses the intermediate transfer belt 47 from the back surface to press the intermediate transfer belt 47 against the surfaces of the image carriers D1 and D2. ing.

1 and 4, the YM and C
An elevating roll 61 is provided between the K primary transfer rolls 48 and 49.
Is arranged. The roll supporting member S3 for supporting the elevating roll 61 is configured and supported similarly to the roll supporting member S2 for supporting the CK primary transfer roll 49. Then, the lifting / lowering roll moving motor M
When the u is rotationally driven, the motor-side pulley 58 'attached to the output shaft of the elevating roll moving motor Mu rotates, and the belt 62, the pulley 63, the rotating shaft 64, and the eccentric cam 66 rotate, and the eccentric cam 66 rotates. The position of the roll support member S3 and the elevating roll 61 is adjusted in the vertical direction by the rotation of.

Therefore, as can be seen from FIGS. 4A and 4B, the roll supporting members S1, S2, S3 are
In the case where the primary transfer rolls 48, 49 are supported at the lower position by 3, 53 and 66, the image transfer members D1, D2
At a distance away from the At this time, as shown in FIG. 4A, the elevating roller 61 is also held at the lowered position, and the intermediate transfer belt 47 is held at a position away from the image carriers D1 and D2. Further, the roll support member S
When 1, S2 and S3 are supported at the raised position by the eccentric cams 53, 53 and 66, the primary transfer roll 4
Reference numerals 8 and 49 are held at pressure contact positions where the image carriers D1 and D2 are pressed against each other. At this time, as shown in FIG. 4B, the elevating roll 61 is held at an ascending position, and the intermediate transfer belt 47 is held at a position in contact with the image carriers D1 and D2. Note that the reference numerals 51 to 59, B, M1, M2, S
The primary transfer roll moving device Im from the element indicated by 1, S2
Is configured.

2 and 3, the belt module B has a backup roll supporting member 67 for supporting the secondary transfer backup roll 44. The backup roll support member 67 is provided at both ends in the front-rear direction (X-axis direction) (outside of the front and rear ends of the belt 47), and has a protruding portion that protrudes below the belt 47. A guide groove 68 for a secondary transfer roll is formed in the protruding portion. When the belt module B is moved from the use position, which is below the image carriers D1 and D2, to an external pull-out position pulled out of the image forming apparatus U, the reference numerals 42 to 67, S1 to S3, M1, and M2 are obtained. Are also moved from the use position to the external withdrawal position.

In FIGS. 1 and 2, a secondary transfer unit 71 is disposed below the secondary transfer backup roll 44. The secondary transfer unit 71 includes a rotating shaft 72.
It has a base member 73 for component rotation that can rotate around. The rotation of the base member 73 around the rotation shaft 72 is performed by an operation lever (not shown). When the recording sheet is jammed between the belt module B and the secondary transfer unit 71, the base member 73 is rotated counterclockwise around the rotation shaft 72 so that the base member 73 is rotated.
Is moved downward, so that the jammed recording sheet can be easily taken out. The secondary transfer backup roll 44 and the secondary transfer roll 74
Is a region where the toner image on the intermediate transfer belt 47 is transferred to the recording sheet passing through that region. An upstream sheet guide 76 is disposed upstream of the secondary transfer area Q3 in the transport direction of the recording sheet. In addition, the secondary transfer backup roller 44 and the secondary transfer roll 74 transfer the secondary transfer device (44+
74) is configured.

In the copying machine main body U1, a first sheet cassette K1 for storing sheets sequentially below the secondary transfer unit 71 downward, and a temporary stock used for double-sided copying. An intermediate cassette K0 and a second paper cassette K2 are detachably housed. And the first
The feeders 77a, 78a, 79 correspond to the sheet cassette K1, the intermediate cassette K0, and the second sheet cassette, respectively.
a, separating roll devices 77b, 78b, 79b and take away roll devices 77c, 78c, 79c are provided, and each of the take away roll devices 77c, 78c, 7 is provided.
Feed sensors SN1, SN2, and SN3 are provided in front of 9c. The intermediate cassette K0 is a tray used when circulating the recording sheet S on which the first copy has been performed at the time of double-sided copying and resending the recording sheet S to the secondary transfer area Q3.

A manual feed tray TR1 is provided at an upper left position of the first sheet cassette K1. Each sheet fed from the manual feed tray TR1 and each of the paper feed cassettes K1 and K2 is temporarily stopped by a registration roller 81 and then conveyed to the transfer area Q3 at a predetermined timing. The secondary transfer roll 74 arranged in the transfer area Q3 transfers the toner image on the surface of the intermediate transfer belt 47 to the recording sheet S passing through the transfer area Q3. After the toner remaining on the surface of the intermediate transfer belt 47 that has passed through the transfer area Q3 is recovered by the belt cleaner 46, it is transported to the primary transfer areas Q1 and Q2 again.

The recording sheet S on which the toner image has been transferred in the transfer area Q3 is guided by the downstream sheet guide 82, and is conveyed to the fixing area Q4 through the conveyance belt 83. A heating roll 84 having a built-in heater is provided in the fixing area Q4.
A fixing device F having a pair of fixing rolls 84 and 85 including a pressure roll 85 is disposed so that an unfixed toner image on the recording sheet S passing through the fixing area Q4 is fixed by heating and pressing. Is configured. In FIG. 1, the secondary transfer unit 71, the transport belt 83 and the fixing device F are supported by a slide frame 87. The slide frame 87 is supported by a rail R4 so as to be slidable in the front-rear direction, and is detachably supported by the image forming apparatus main body.

The recording sheet S on which the toner image has been fixed in the fixing area Q4 is placed on a discharge roll 88 disposed downstream thereof.
From the sheet discharge tray TR2. A switching gate 89 is provided upstream of the discharge roll 88.
Is arranged. The switching gate 89 is connected to the fixing area Q.
The conveyance direction of the recording sheet S that has passed through 4 is changed to the branch conveyance path 91.
Alternatively, it is used when switching to the direction of the sheet discharge tray TR2. The branch transport path 91 is a mylar gate 92
And is connected to the sheet reversing path 93 via the. The mylar gate 92 is a sheet-like and comb-shaped member. When the passing recording sheet S is conveyed downward, the recording sheet S is allowed to move downward by elastic deformation and passes through the mylar gate 92. When the recording sheet S is switched back and conveyed upward, the recording sheet S is guided in the direction of the intermediate cassette K0. The recording sheet S once stored in the intermediate cassette K0 is sent out from the sending roll 78a and is re-conveyed to the transfer area Q3. The recording sheet conveying device (76 to 79 + 82 +
83).

In FIG. 6, a controller C has a CPU
(Central processing unit), a microcomputer having a ROM (read only memory), a RAM (random access memory), an I / O (input / output interface) and the like. The controller C includes a copy start signal input from the UI, a set number of copies, a color mode, a YM image carrier rotation speed Sd1a, a CK image carrier rotation speed Sd2a, an intermediate transfer belt rotation speed Sva, and the like. Input signal is being input.

The controller C outputs control signals for the following circuits and other operation circuits in accordance with the input signals. The YM roll moving motor drive circuit Ey drives the YM roll moving motor M1 that moves the YM primary transfer roll 48 up and down, that is, to the pressing position and the separated position. The CK roll moving motor drive circuit Ec is a CK roll moving motor M2 for moving the CK primary transfer roll 49 between the pressed position and the separated position.
Drive. The YM image carrier driving circuit Em drives a YM image carrier driving motor Mm for rotating the YM image carrier D1. The CK image carrier driving circuit Ek is the CK
The CK image carrier driving motor Mk for rotating the image carrier D2 is driven. The intermediate transfer belt motor drive circuit Ev drives an intermediate transfer belt drive motor Mv that rotates the intermediate transfer belt 47. The lifting roll moving motor drive circuit Eu drives a lifting roll moving motor Mu that moves the lifting roll 61 up and down, that is, moves the pressing roll to a pressing position and a separated position.

The ROM of the controller C stores a program that operates according to each of the input signals and necessary data. The controller C operated by the program includes a rotational speed comparing means C1, a pressing member movement control means C2, a color mode determination flag FL.
1. It has a function such as a primary transfer end determination flag FL2. C1: Rotation speed comparison means The rotation speed comparison means C1 compares whether the YM image carrier rotation speed Sd1a, the CK image carrier rotation speed Sd2a, and the intermediate transfer belt rotation speed Sva are the same rotation speed.

C2: Pressure Member Movement Control Means The pressure member movement control means C2 controls the YM image carrier rotation speed Sd1a, the CK image carrier rotation speed Sd2a, and the intermediate transfer belt rotation in the case of full-color image forming operation. When the speed Sva is the same rotation speed (steady speed), the primary transfer rolls 48 and 49 and the elevating roll 61 are moved to the pressing position, and the intermediate transfer belt 47 is pressed against the surfaces of the image carriers D1 and D2. Control. After the completion of the primary transfer, the primary transfer rolls 48 and 49 and the elevating roll 61 at the pressing position are moved to the separation position, and the intermediate transfer belt 47 is controlled to be separated from the surfaces of the image carriers D1 and D2. I do. In the case of a single-color image forming operation, the CK
When the rotation speed Sd2a for image carrier and the rotation speed Sva for intermediate transfer belt are the same rotation speed (steady speed), the primary transfer roll 49 is moved to the pressure contact position, and the surface of the image carrier D2 for CK is moved. The intermediate transfer belt 47 is pressed, and after the primary transfer, the primary transfer roll 49 at the pressed position is moved to the separation position to control the intermediate transfer belt 47 to be separated from the surface of the image carrier D2. . The pressing device movement control means C2, the YM roll movement motor drive circuit Ey, the CK roll movement motor drive circuit Ec, and the elevating roll movement motor drive circuit Eu constitute a movement device control device Ic.

FL1: Color mode determination flag The color mode determination flag FL1 is “0” when the color mode is selected by the user, and is “1” when the single color mode is selected. It is. FL2: Primary transfer end determination flag The primary transfer end determination flag FL2 becomes "1" when the writing end position of the first electrostatic latent image on the image carrier passes through the developing area, and becomes the last electrostatic latent image. Is a flag that becomes "0" when the end position of the image passes the primary transfer position. In the double-sided copy mode, the writing end position of the first electrostatic latent image on the first side becomes "1" when passing through the developing area, and the end position of the last electrostatic latent image on the second side is the primary transfer. "0" when passing the position
Is a flag.

(Operation of Embodiment 1) FIG. 7 is a flowchart of the control for raising and lowering the primary transfer roll. The drive and stop of the image carriers D1, D2 and the intermediate transfer belt 47 are controlled by the main flow of the image forming operation of the image forming apparatus, and are not shown in the control of FIG. The process shown in FIG. 7 starts at the same time when the power of the image forming apparatus is turned on. In ST1 (step 1) of FIG. 7, it is determined whether the copy start switch has been turned on. No (N)
In this case, step ST1 is repeatedly executed. ST1
If the answer is YES (Y), the process moves to ST2. In ST2, it is determined whether or not the document is a color document. This determination is made based on whether the color mode determination flag FL1 is "0" or "1". If the determination is yes (Y), that is, if the color mode determination flag FL1 = 0 (color mode), the process proceeds to ST3. YM image carriers D1, C that have started rotating in ST3
It is determined whether the rotation speed (steady speed) of the image carrier D2 for K and the rotation speed (steady speed) of the intermediate transfer belt 47 have become the same. If no (N), ST3 is repeatedly executed. If yes (Y), the process moves to ST4. In ST4, the YM primary transfer roll 48, the CK primary transfer roll 49, and the elevating roll 61 at the separated positions are moved to the pressure contact position. By this operation, the surface of the intermediate transfer belt 47 is pressed against the image carriers D1 and D2. In ST5, it is determined whether or not the last primary transfer of the job is completed. If no (N), ST5 is repeatedly executed. If yes (Y), the process moves to ST6. In ST6, the YM primary transfer roll 48 at the pressure contact position,
The CK primary transfer roll 49 and the elevating roll 61 are moved to the separated position. By this operation, the surface of the intermediate transfer belt 47 is separated from the image carriers D1 and D2. ST
After the end of 6, the process returns to ST1.

In the above ST2, if the result is NO (N), that is, if the color mode determination flag FL1 = 1 (monochrome mode), the process proceeds to ST7. In ST7, it is determined whether or not the rotation speed (steady speed) of the CK image carrier D2 started to rotate and the rotation speed (steady speed) of the intermediate transfer belt 47 are the same. The rotation of the YM image carrier D1 remains stopped. If no (N), ST7 is repeatedly executed. If yes (Y), the process moves to ST8. In ST8, the CK primary transfer roll 49 at the separation position is moved to the pressure contact position. By this operation, the surface of the intermediate transfer belt 47 is pressed against the CK image carrier D2. In ST9, it is determined whether or not the last primary transfer of the job is completed. This determination is made based on whether the primary transfer end determination flag FL2 is "0". If no (N), ST9 is repeatedly executed. If yes (Y), proceed to ST10. In ST10, the CK primary transfer roll 49 at the pressure contact position is moved to the separation position. By this operation, the surface of the intermediate transfer belt 47 is separated from the CK image carrier D2.
After the end of ST10, the process returns to ST1.

The recording sheet S on which the toner image has been secondarily transferred is fixed by a fixing device F, and is discharged to a discharge tray TR2 for one-sided copying, and the sheet reversing path 93 and the intermediate tray K0 for two-sided copying. Then, it is re-sent to the secondary transfer area Q3 in an inverted state. When the intermediate transfer belt 47 or the image carriers D1 and D2 are replaced or cleaned, for example, at the end of the secondary transfer, the intermediate transfer belt 47 is used.
The belt module B supporting the above is pulled out of the image forming apparatus U. At this time, since the intermediate transfer belt 47 and the image carriers D1 and D2 are separated from each other, the intermediate transfer belt 47 and the image carriers D1 and D2 that move together with the belt module B do not rub against each other. Wear or damage due to frictional contact between the carriers D1, D2 and the intermediate transfer belt 47 can be prevented.

When forming an image of only a single color K (black) toner image as described above, the CK primary transfer roll 49 is moved to the pressure contact position to move the intermediate transfer belt 47 to the CK position. The image carrier D2 is pressed against the image carrier D2, but not pressed against the image carrier D1 for YM. Therefore, even if the intermediate transfer belt 47 is rotating, the YM image carrier D1, which is not used for image formation, does not come into frictional contact, and wear due to contact friction is small. Therefore, the surface of the intermediate transfer belt 47 or the surface of each of the image bearing members D1 and D2 is hardly damaged by abrasion, and the life is prolonged. Further, in the case of the single-color image formation, since the rotation of the YM image carrier D2 is stopped, the cost of the power supply for the rotational driving is not required.

(Embodiment 2) FIG. 8 is a detailed explanatory view of a transfer roll moving device provided in an image forming apparatus according to Embodiment 2 of the present invention. FIG. 8A is a detailed explanatory view as viewed from the front and rear, and FIG. FIG. 8B is a sectional view taken along line VIIIB-VIIIB of FIG. 8A. In the description of the second embodiment, components corresponding to the components of the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. The second embodiment is different from the first embodiment in the following points, but is otherwise different from the first embodiment.
It is configured similarly to.

In FIG. 8, a roll support member S21 slidably supported up and down by a guide member 52 fixed to the belt support frame 41v is connected to the primary transfer roll 49 for CK via a bearing 51 at an upper end. Is rotatably supported. The rotation shaft 49a
Of the CK primary transfer roll 49
A spacer 49c is arranged between the end face of the roll 49a of the above and the bearing 51. A cylindrical cam contact member guide portion 9 is provided inside the roll support member S21.
6 are formed. A guide hole 96a is provided inside the cam contact member guide portion 96, and the guide hole 9a is provided.
A substantially cylindrical distal end portion 97a of the cam contact member 97 is guided by 6a so as to be movable in the vertical direction (separating direction). The cam contact member 97 has a screw portion 97b having a diameter larger than the tip portion 97a below the tip portion 97a and having a thread formed on the outer peripheral surface, and a screw portion 97 below the screw portion 97b.
It has a plate-shaped cam contact portion 97c larger than the diameter of b.
The eccentric cam 53 contacts the cam contact portion 97c. A spring receiving seat 98 is disposed above the cam contacting portion 97c, and a screw portion 97b of the cam contacting member 97 is threaded through a center portion of the spring receiving seat 98.

A compression spring 99 is disposed on the outer peripheral side of the cam contact member guide portion 96 inside the roll support member S21, and the lower end of the compression spring 99 is in contact with the spring receiving seat 98. ing. Accordingly, the spring receiving seat 98, which is screwed through the threaded portion 97b of the cam contact member 97, is moved up and down to adjust the pressure of the compression spring 99 to easily increase the primary transfer pressure. It can be changed. Incidentally, the spring receiving seat 98 can be omitted. The compression spring 99 is rotated by the rotation of the eccentric cam 53 to lower the cam contact member 97 and the spring receiving seat 98.
When the position of the roll 49a of the next transfer roll 49 moves to a lower position (separation position), the intermediate transfer belt 4 against which the roll 49a of the primary transfer roll 49 presses from the back side.
The surface and the surface of the image carrier D2 have a predetermined spring force and length.

The eccentric cam 53 is supported by a cam rotation shaft 54, and the cam rotation shaft 54 is rotatably supported by a bearing 56. A pulley 57 is disposed between the eccentric cam 53 and the bearing 56, and a spacer Sp is disposed between the pulley 57 and the eccentric cam 53. The pulley 57 and the spacer Sp are supported by the cam rotation shaft 54, and the spacer S
The p prevents the eccentric cam 53 and the pulley 57 from moving in the axial direction. The eccentric cam 53
The pulley 57 is supported by a cut portion of the cam rotation shaft 54 for preventing rotation. The rotational force of a motor-side pulley 58 attached to the output shaft of the CK roll moving motor M2 is transmitted to the pulley 57 via a belt 59. Therefore, the belt 59, the pulley 57, the rotating shaft 54 and the eccentric cam 53 also rotate when the CK roll moving motor M2 is rotationally driven in the second embodiment. The rotation of the eccentric cam 53 causes the cam contact member 9 to rotate.
7 moves in the vertical direction (separating direction), and the compression spring 99 moves.
The position of the roll supporting member S21 and the primary transfer roll 49 for CK is adjusted in the vertical direction through the control unit. A roll support member (not shown) that supports the primary transfer roll 48 and the elevating roll 61 is also configured and supported similarly to the roll support member S21.
The roll support member S21 and the primary transfer roll 4 for CK
It is configured to be position-adjusted in the same manner as 9.

Therefore, also in the second embodiment, in the case of full-color image formation, at the time of the primary transfer, the primary transfer rolls 48 and 49 and the elevating roll 61 are moved to the pressure contact position to clean the surface of the intermediate transfer belt 47. The surfaces of the image carriers D1 and D2 are pressed against each other, and when the last primary transfer job is completed, the primary transfer rolls 48 and 49 and the elevating roll 61 are moved to the separated positions. In the case of forming a single color image, only the CK primary transfer roll 49 corresponding to the CK image carrier D2 is moved to the pressing position or the separated position so that the surface of the intermediate transfer belt 47 is moved to the surface of the image carrier D2. Press or separate. Therefore, after the end of the last primary transfer, the image carriers D1, D2 and the intermediate transfer belt 47
And a belt module B supporting the intermediate transfer belt 47 for maintenance and other operations.
The intermediate transfer belt 47 and the image carrier D
1, Does not rub against D2. Therefore, the second embodiment also has the same operation as the first embodiment.

(Embodiment 3) FIG. 9 is an explanatory view of an image forming apparatus according to Embodiment 3 of the present invention. The third embodiment differs from the first embodiment in the following points, but has the same configuration as the first embodiment in other points. In the third embodiment, four image carriers Dy to Dk for forming toner images of respective colors are arranged in tandem. Below the image carriers Dy to Dk, a sheet transport belt 103 supported by a driving roll 42, a peeling roll 102, a tension roll 43, and an idler roll 44 is disposed. The transfer rolls 104y to 104k on the back side of the sheet conveying belt 103 correspond to the transfer positions Qy to Qk on the image carriers Dy to Dk.
104k are arranged.

Each of the transfer rolls 104y to 104k is rotatably supported by one end of an L-shaped roll support member 106. Each of the roll support members 106 has a rotation center 10 fixed to the belt support frame 41v.
A tension spring 107 fixed to the belt supporting frame 41v is fixed to the roll supporting member 106 on the non-support side of the transfer rolls 104y to 104k. The tension spring 107 is urged in a direction to separate the transfer rolls 104y to 104k from the back surface of the sheet conveying belt 103. When transferring the toner images on the image carriers Dy to Dk, the operating shaft SLa of each solenoid SL operates the transfer rolls 104y to 104k in the direction of pressing the back surface of the sheet conveying belt 103, and the image is transferred. The sheet conveying belt 103 is pressed against the surfaces of the carriers Dy to Dk.

FIG. 10 is a flowchart of control of the movement of the transfer roll provided in the image forming apparatus according to the third embodiment of the present invention. In the case of full color printing, in ST3, ST4, ST5, and ST6 of the flowchart shown in FIG. 7, when the YM image carrier D1 and the CK image carrier D2 and the intermediate transfer belt 47 have the same rotational speed, Next transfer roll 48, 49
In addition, the elevating roller 61 is moved to the pressure contact position, and at the end of the last primary transfer of the job, the primary transfer rollers 48, 49 and the elevating roller 61 are moved to the separated position. ST4 ', ST5',
In ST6 ', when the image carriers Dy, Dm, Dc, and Dk and the sheet conveying belt 103 have the same rotation speed, the transfer rolls 104y to 104k are moved to the pressure contact position, and the last transfer of the job is completed. At this time, the transfer rolls 104y to 104k at the pressing position are moved to the separation position. Also,
In the case of forming a monochrome image, the image carrier Dk for K (black) and the sheet conveying belt 103 have the same rotational speed in ST7 ', ST8', ST9 ', and ST10' of the flowchart shown in FIG. Is reached, the transfer roll 104k is moved to the pressure contact position, and when the last transfer of the job is completed, the transfer roll 104k at the pressure contact position is moved to the separation position. Therefore, during the non-image formation, the image carriers Dy to Dk and the sheet conveying belt 103
The sheet conveying belt 103 and the image carriers Dy to Dk do not rub against each other even if the belt module B supporting the sheet conveying belt 103 is moved for work such as maintenance. Therefore, the third embodiment also has the same operation as the first embodiment.

(Embodiment 4) FIG. 11 is an explanatory view of the positional relationship between the primary transfer corotron and the intermediate transfer belt and the image carrier provided in the image forming apparatus according to Embodiment 4 of the present invention.
1A is a diagram showing the position of the primary transfer corotron in a state where the intermediate transfer member and the image carrier are separated, and FIG. 11B is a diagram showing the position of the primary transfer corotron in a state where the intermediate transfer member and the image carrier are in contact with each other. . The fourth embodiment differs from the first embodiment in the following points, but has the same configuration as the first embodiment in other points.

In the fourth embodiment, for YM of the first embodiment,
Instead of primary transfer rolls 48 and 49 for CK, for YM, C
Primary transfer corotron 48 ', 49' for K (primary transfer unit)
Is arranged. In the fourth embodiment, the lifting roll 61 of the first embodiment is omitted. Belt pressure rolls 108, 108 are disposed on both sides of the CK primary transfer corotron 49 'in the moving direction of the intermediate transfer belt 47, respectively. Each of the belt pressing rolls 108, 10
The roll supporting members S22 and S22 for supporting the CK primary transfer roll 49 of the first embodiment are each configured and supported similarly to the roll supporting member S2 for supporting the CK primary transfer roll 49 of the first embodiment. When the CK belt pressing roller moving motor M2 'is rotationally driven, the motor-side pulley 58 rotates, and the belt 59, the pulley 57, and the eccentric cam 53 rotate, and the roll supporting member S22 and the belt pressing roller 108 are rotated. It is configured to be adjusted in the vertical direction.

Belt pressure rolls 108, 108 are also arranged on both sides of the YM primary transfer corotron 48 'in the moving direction of the intermediate transfer belt 47, and the belt pressure rolls 108 of the CK primary transfer corotron 49' are arranged. , 108
The configuration is such that the CK belt pressing roller moving motor M1 'is rotated and the roll supporting member S12 and the belt pressing roller 108 are adjusted in the vertical direction. Note that the reference numerals 51 to 59, B, M
A pressing roll moving device Im 'is constituted by the elements indicated by 1', M2 ', S12 and S22. The pressing roller moving device Im 'is operationally controlled by a movement control device (not shown), and moves to the pressing position during image forming operation of the corresponding image carriers D1, D2, and separates during the non-image forming operation. It is designed to move to a position. Therefore, in the fourth embodiment, each of the belt pressing rollers 108 moves to the pressing position during the image forming operation and moves to the separated position during the non-image forming operation to move the intermediate transfer belt 47 to the image carrier D1, D2. Since it is separated from and connected to D2, the same operation as in the first embodiment is achieved.

(Embodiment 5) FIG. 12 is an explanatory view of an image forming apparatus according to Embodiment 5 of the present invention. The fifth embodiment differs from the third embodiment in the following points, but has the same configuration as the third embodiment in other points. In the fifth embodiment, transfer corotrons (transfer devices) 104y 'to 104k' are arranged in place of the transfer rolls 104y to 104k of the third embodiment. Belt pressure rolls 108 are disposed downstream of the transfer corotrons 104y 'to 104k' in the moving direction of the sheet conveying belt 103, respectively. Each of the belt pressure contact rolls 108 and the roll support member Sb that supports the belt pressure contact rolls 108 are driven by rotating the belt pressure contact roll moving motor Mb, whereby the motor-side pulley 58 rotates, and the belt 59, the pulley 57, and Eccentric cam 53
Are rotated, and the position of each of the roll supporting members Sb and the belt pressing roller 108 is adjusted in the vertical direction.

The reference numerals 51 to 59, B, Mb, Sb
The pressing roll moving device Im ″ is composed of the elements indicated by the following symbols. The operation of the pressing roll moving device Im ″ is controlled by a moving control device (not shown), and the corresponding image carriers Dy, Dm, and Dc. , Dk move to the pressed position during the image forming operation, and move to the separated position during the non-image forming operation. Therefore, in the fifth embodiment as well, each of the belt pressing rollers 108 moves to the pressing position during the image forming operation and moves to the separated position during the non-image forming operation to move the sheet conveying belt 103 to the image carriers Dy, Dm, and Dm. D
Since they are separated from and contacted with c and Dk, the same operation as in the third embodiment is achieved. (Modifications) Although the embodiments of the present invention have been described in detail, the present invention is not limited to the above-described embodiments, and various modifications may be made within the scope of the present invention described in the appended claims. It is possible to make changes. Modified embodiments of the present invention will be exemplified below.

(H01) In the first, second and fourth embodiments, the configuration in which the intermediate transfer belt is separated from the surface of the image carrier at the end of the primary transfer of the last image formation is exemplified. A configuration in which the intermediate transfer belt is separated from the surface of the image carrier at the end of the transfer can also be changed. (H02) In the first, second, and fourth embodiments, it is possible to arrange four image carriers for each toner color. (H03) In the third and fifth embodiments, it is possible to arrange two image carriers for every two colors. (H04) In the above embodiments, the first color is Y (yellow), the second color is M (magenta), the third color is C (cyan), and the fourth color is K (black). , M, C and Y, K, M, C
The order of the toner colors can be changed.

[0075]

The above-described image forming apparatus of the present invention has the following effects. (E01) When the belt module is moved between the use position inside the image forming apparatus and the external pull-out position outside, the belt module can be prevented from contacting the image carrier. In the use position, the belt of the belt module can be easily pressed against or separated from the image carrier. (E02) Since the contact time between the image carrier and the belt of the belt module can be shortened, the abrasion due to the contact friction can be reduced.

[Brief description of the drawings]

FIG. 1 is an overall explanatory diagram of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is an enlarged view of a main part on the left side (Y direction side) of the image forming apparatus shown in FIG.

FIG. 3 is a perspective view of a belt module.

FIG. 4 is an explanatory diagram of a positional relationship between a primary transfer roll, an intermediate transfer belt, and an image carrier; FIG. 4A shows a position of the primary transfer roll in a state where the intermediate transfer member and the image carrier are separated; FIG. 4B is a diagram showing the position of the primary transfer roll in a state where the intermediate transfer member and the image carrier are in contact with each other.

5 is a detailed explanatory view of the primary transfer roll position adjusting device shown in FIG. 2; FIG. 5A is a detailed explanatory view seen from the direction shown in FIG. 2; and FIG. 5B is an arrow VB- in FIG. 5A. 5C is a sectional view taken along line VB, and FIG. 5C is a sectional view taken along line VC-VC of FIG. 5A.

FIG. 6 is a block diagram of the first embodiment.

FIG. 7 is a flowchart of the control of raising and lowering the primary transfer roll.

FIG. 8 is a detailed explanatory view of a transfer roll moving device provided in the image forming apparatus according to the second embodiment of the present invention. FIG. It is arrow VIIIB-VIIIB sectional drawing.

FIG. 9 is an explanatory diagram of an image forming apparatus according to a third embodiment of the present invention.

FIG. 10 is a flowchart of transfer control of a transfer roll provided in an image forming apparatus according to a third embodiment of the present invention.

FIG. 11 is an explanatory diagram of a positional relationship between a primary transfer corotron, an intermediate transfer belt, and an image carrier provided in an image forming apparatus according to a fourth embodiment of the present invention. FIG. FIG. 11B is a diagram illustrating the position of the primary transfer corotron in a state where the carrier is separated, and FIG. 11B is a diagram illustrating the position of the primary transfer corotron in a state where the intermediate transfer member and the image carrier are in contact with each other.

FIG. 12 is an explanatory diagram of an image forming apparatus according to a fifth embodiment of the present invention.

[Explanation of symbols]

B: Belt module, (Gy, Gm, Gc, Gk): Developing device, (D1, D2), (Dy, Dm, Dc, Dk): Image carrier, Ic: Moving device control device, Im: Primary transfer Roll moving device, transfer roll moving device, Im'Im "... Pressing roll moving device, (Qy, Qm, Qc, Qk) ... Transfer area, (Qy,
Qm, Qc, Qk) (Q1, Q2) ... primary transfer area, Q3 ... 2
Next transfer area, S: recording sheet, 41: module frame, (44 + 74): secondary transfer unit, 47: intermediate transfer belt, (48, 49): primary transfer roll, (48 ', 4)
9 '): primary transfer unit, (76 to 79 + 82 + 83): recording sheet conveying device, 103: sheet conveying belt, 104
y to 104k: transfer roll, 104y 'to 104k': transfer unit, 108: belt pressing roller

 ──────────────────────────────────────────────────の Continued on the front page (72) Takashi Takeuchi, 2274 Hongo, Fuji Xerox Co., Ltd., Ebina, Kanagawa Prefecture

Claims (4)

[Claims] 1. An image forming apparatus having the following requirements: (A01) An endless surface in which rotating shafts extending in a horizontal direction are arranged in parallel with each other and rotate and move around the rotating shaft. A plurality of image carriers on which an electrostatic latent image is formed, (A02) a developing device for developing each electrostatic latent image on the surface of each image carrier into a toner image, and (A03) a developing device along each surface of the image carrier. (A04) an intermediate transfer belt that rotates and moves through a primary transfer area that is respectively set, and a press-contact position where the intermediate transfer belt is pressed in each of the primary transfer areas and pressed against the surface of the image carrier. A plurality of transfer belt surfaces are arranged so as to be movable between a separation position where the transfer belt surface is separated from the image carrier surface, and a toner image on each of the plurality of image carrier surfaces is transferred to the intermediate transfer belt at the pressure contact position. Each primary transfer (A05) a recording sheet transporting device that transports and passes a recording sheet to a secondary transfer area set in the movement path of the intermediate transfer belt; (A06) an intermediate transfer belt disposed in the secondary transfer area A secondary transfer device for transferring the upper toner image onto the recording sheet;
A primary transfer roll moving device for independently moving the next transfer roll between the pressure contact position and the separation position and always holding the separation roll at the separation position; (A08) operating the primary transfer roll movement devices; A moving device control device for controlling each of the primary transfer rolls to move to the pressing position during the image forming operation of the corresponding image carrier and to the separation position during non-image formation; (A09) the intermediate transfer belt; Each of the primary transfer rolls, the primary transfer roll moving device, and a module frame for supporting the primary transfer rolls, and having the image carrier between a use position below each image carrier and an external withdrawal position pulled out of the apparatus. Belt module that can move in the body axis direction. 2. An image forming apparatus characterized by the following requirements: (B01) An endless surface in which rotating shafts extending in a horizontal direction are arranged in parallel with each other and rotate and move around the rotating shaft. A plurality of image carriers on which an electrostatic latent image is formed, (B02) a developing device for developing each electrostatic latent image on the surface of each of the image carriers into a toner image, and (B03) a developing device along the surface of each image carrier. (B04) a pressing position for pressing the sheet conveying belt in each of the transfer areas to press the sheet against the surface of the image carrier, and the sheet conveying. A plurality of transfer members each of which is movably disposed between a belt surface and a separated position where the belt surface is separated from the surface of the image carrier, and which transfers toner images on the plurality of image carrier surfaces to the recording sheet at the pressing position; Roll, (B05) a transfer roll moving device that moves each of the transfer rolls independently between the pressure contact position and the separation position and always holds the transfer roll at the separation position, and (B06) operation of the transfer roll movement device. And (B07) the sheet conveying belt, wherein the transfer rollers move the transfer rollers to the press-contact position during image formation of the corresponding image carrier and to the separation position during non-image formation. It has a transfer roll, the transfer roll moving device and a module frame for supporting the transfer roll, and moves in the axial direction of the image carrier between a use position below each image carrier and an external pull-out position pulled out of the device. Possible belt module. 3. An image forming apparatus having the following requirements: (C01) an endless surface in which rotating shafts extending in a horizontal direction are arranged in parallel with each other and rotate and move around the rotating shaft; A plurality of image carriers on which an electrostatic latent image is formed, (C02) a developing device for developing each electrostatic latent image on the surface of each image carrier into a toner image, and (C03) a developing device along the surface of each image carrier. (C04) a primary transfer device that transfers a toner image on the surface of the image carrier to the intermediate transfer belt in each of the primary transfer regions. (C05) a recording sheet transporting device for transporting and passing a recording sheet to a secondary transfer area set in the movement path of the intermediate transfer belt, (C06) being disposed in the secondary transfer area, and Toner image on the recording sheet A secondary transfer device for transferring, (C07) a pressure contact position disposed on the back side of the intermediate transfer belt corresponding to each of the image carriers and pressing the intermediate transfer belt to press against the surface of the image carrier; A plurality of belt press-contact rolls each of which is movable between a separation position at which the surface of the intermediate transfer belt is separated from the surface of the image carrier; and (C08) the belt press-contact roll is moved between the press position and the separation position. (C09) controlling the operation of the pressing roll moving device so that each of the belt pressing rolls is moved to the corresponding image carrier to form an image. (C010) the intermediate transfer belt, the primary transfer unit, the belt pressure contact roll, A belt having a pressure-contact roll moving device and a module frame for supporting the same, and movable in the axial direction of the image carrier between a use position below each of the image carriers and an external pull-out position pulled out of the device; module. 4. An image forming apparatus having the following requirements: (D01) An endless surface in which rotating shafts extending in a horizontal direction are arranged in parallel with each other and rotate around the rotating shaft. A plurality of image carriers on which an electrostatic latent image is formed, (D02) a developing device for developing each electrostatic latent image on the surface of each image carrier into a toner image, and (D03) a developing device along the surface of each image carrier. (D04) a transfer belt for transferring the toner image on the surface of the image carrier to a recording sheet passing through the transfer region on the surface of each image carrier. (D05) disposed on the back side of the sheet conveying belt corresponding to each of the image carriers;
A plurality of belt pressing rolls each of which is movable between a pressing position where the sheet conveying belt is pressed and pressed against the surface of the image carrier and a separated position where the surface of the sheet conveying belt is separated from the surface of the image carrier; D06) a pressure roller moving device that moves each of the belt pressure rollers independently between the pressure position and the separation position and always maintains the pressure roller at the separation position; and (D07) controls the operation of the pressure roller movement device. A moving device control device that moves the belt pressing roller to the pressing position during image formation corresponding to each of the image carriers and to the separation position during non-image formation; (D08) the sheet conveying belt; The transfer device, the belt pressure roller, the pressure roller moving device, and a module frame for supporting the same; Movable belt module in the axial direction of said image bearing member with an external extended position drawn out of the device and use positions.