JP5500439B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a color copying machine, a color printer, a facsimile machine, or a multifunction machine having these functions.

  In recent years, there has been an increasing demand for improvement in printing speed and image quality in color image formation, and so-called quadruple tandem image forming apparatuses have been adopted in response to this demand. In such an image forming apparatus, four image forming units including an image carrier and a developing device are arranged facing a belt device such as a conveyance belt or a transfer belt (for four colors), and toner on the image carrier is arranged. The image is sequentially transferred onto transfer paper or a transfer belt, and a full color image can be formed in a short time.

  Such an image forming apparatus includes, for example, yellow (Y), magenta (M), cyan (C), and black (K) image forming units, and uses the four color image forming units when forming a color image. Thus, a color mode for acquiring a full color image and a monochrome mode for acquiring a monochrome image using an image forming unit of only a single color such as black can be selected. For this reason, an image forming unit other than black is not operated during monochrome printing. Here, it is possible to form an image without switching the mode, but in this case, a problem such as consumption of color toner occurs even when a monochrome image is formed.

  For this reason, when switching from the color mode to the monochrome mode, it is necessary to stop driving the color image forming unit. In such a case, the photosensitive member remains in contact with the transfer belt and the life of the image forming unit is shortened. There is a problem that it ends up.

  In order to cope with this, Patent Document 1 discloses a first position where the image forming unit is pressed against the conveying belt in an image forming apparatus that does not transfer a toner image in the color image forming unit during monochrome image formation. An apparatus that includes an up / down mechanism that moves the image forming unit up and down to a second position that is separated from the conveying belt by a predetermined distance and that uses a driving source used for an image forming operation of the image forming unit as its driving source is described. Has been.

  Patent Document 2 describes a cam mechanism that realizes, in a color laser printer, a mechanism that performs an operation of bringing a transfer roller into contact with an intermediate transfer belt and a mechanism of moving the transfer roller away from the intermediate transfer belt with a simple mechanism.

  However, a mechanism for moving the color image forming unit away from the transfer belt when switching to a monochrome image, such as those described in Patent Document 1 and Patent Document 2, is complicated and necessary. There is a problem that a large space becomes large. In such an image forming apparatus, a transfer material such as paper may be clogged between the image forming unit and the transfer device. In such a case, the image forming unit and the transfer device are separated from each other. There is also a demand for it.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus that has a simple structure, can be easily switched between a color mode, a monochrome mode, and a jam processing mode while reducing cost and space. .

The invention of claim 1
A plurality of image carriers on which electrostatic charging images are formed so that the charging means for charging the surface is integrally movable, and the electrostatic latent images are arranged corresponding to the image carriers, and the electrostatic latent images are converted into toner images. In an image forming apparatus comprising: a plurality of developer carriers to be developed as a transfer device; and a transfer device that transfers a toner image on the image carrier to a transfer material.
A switching mechanism having a common position setting member that linearly moves to set each developer carrier and each image carrier in a variable position and a drive unit that linearly moves the position setting member ;
Color mode for color image formation and monochrome mode for monochrome image formation can be set,
In the color mode, the switching mechanism moves the developer carrier to a development position where the corresponding image carrier can be developed,
In the monochrome mode, the switching mechanism places one developer carrier at a development position where the corresponding image carrier can be developed and develops the other image carrier corresponding to the other developer carrier. It moved to non-separated position which is an image forming apparatus according to claim Rukoto.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the switching mechanism is provided in the driving unit and is rotationally driven, and the position setting member is engaged with the pinion. A rack that linearly drives the position setting member, and a linear cam portion that supports both ends of the developer carrier and changes the positions of the developer carriers and the image carrier. It is characterized by that.

According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect , a jam clearing mode for clearing a paper jam can be set. together to separate the body from the transfer device, and wherein the moving together said developer carrying member with the movement of the image bearing member.

A fourth aspect of the present invention, in the image forming apparatus according to any one of claims 1 to 3, comprising a sensor for detecting the position of the positioning member, the positioning member by the sensor detecting the arrangement state and detecting the mode set in the image forming apparatus.

According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, the development is performed by a contact method using a one-component developer.

A sixth aspect of the present invention is the image forming apparatus according to any one of the first to fifth aspects, wherein the transfer device includes an endless belt.

A seventh aspect of the present invention is the image forming apparatus according to the sixth aspect, wherein the endless belt also serves as a paper conveying belt.

According to an eighth aspect of the present invention, in the image forming apparatus according to any one of the first to seventh aspects, the driving unit is a stepping motor.

According to a ninth aspect of the present invention, in the image forming apparatus according to any one of the first to eighth aspects, at least a part of the members constituting the switching mechanism is made of POM (polyacetal). Features.

  According to the image forming apparatus of the present invention, the switching includes a common position setting member that linearly moves and sets each developer carrier and each image carrier so that the position is variable, and a drive device that linearly moves the position setting member. Since the mechanism is provided, the apparatus can have a simple structure, and the switching process between the color mode, the monochrome mode, and the jam processing mode can be performed while reducing cost and space.

1 is a schematic diagram illustrating a schematic configuration of an image forming apparatus according to an embodiment. 1 is a cross-sectional view illustrating an image forming unit of an image forming apparatus according to an embodiment. It is a perspective view which shows the drive device which concerns on an Example. The drive device in a color mode is shown, (a) is a front view, (b) is an enlarged view of the D section in (a). It is a front view which shows the drive device in monochrome mode. It is sectional drawing which shows the drive device in monochrome mode. It is a front view which shows the drive device in jam clearance mode. The drive device in jam clearance mode is shown, (a) is sectional drawing, (b) is an enlarged view of the E section in (a). It is a partial expansion perspective view of the drive device concerning an example.

  The present invention provides an image forming apparatus, wherein a plurality of image carriers on which an electrostatic latent image is formed so that charging means for charging a surface can be integrally moved, and are arranged corresponding to the image carriers. An image forming apparatus comprising: a plurality of developer carriers that develop the electrostatic latent image as a toner image; and a transfer device that transfers the toner image on the image carrier to a transfer material. A switching mechanism having a common position setting member for arranging each developer carrier and each image carrier at a predetermined position in the vertical direction and a drive device for linearly moving the position setting member. According to this example, the apparatus can have a simple structure, and the switching process between the color mode, the monochrome mode, and the jam processing mode can be easily performed while achieving cost reduction and space saving.

  In the image forming apparatus according to the present invention, the switching mechanism is provided on the drive member and is rotationally driven, and the position setting member is engaged with the pinion and linearly drives the position setting member. And a linear motion cam portion that supports both ends of the developer carrier and the developer carrier to change the positions of the developer carrier and the image carrier. According to this example, the switching operation of each mode can be performed with a simple configuration of a rack and a pinion.

  In the image forming apparatus, the image forming apparatus includes a color mode for forming a color image and a monochrome mode for forming a monochrome image. In the color mode, the switching mechanism includes the plurality of developer carriers. The corresponding image carrier is moved to a development position where development is possible, and in the monochrome mode, the switching mechanism places one developer carrier at a development position where the corresponding image carrier can develop and another development. The agent carrier is moved to a separated position where the corresponding image carrier cannot be developed. According to this example, in the monochrome mode, consumption of the developer in other image forming units can be suppressed.

  In the image forming apparatus, the image forming apparatus includes a jam clearing mode for clearing a paper jam. In the jam clearing mode, the switching mechanism separates the image carrier from the transfer device, and The developer carrier is moved in accordance with the movement of the image carrier. According to this example, the image carrier can be separated from the transfer device with a simple mechanism, and the jam clearing process can be easily performed.

  In the image forming apparatus, the image forming apparatus includes a sensor that detects an arrangement position of the position setting member, detects an arrangement state of the moving member, and detects a mode in which the image forming apparatus is set. According to this example, the mode in which the image forming apparatus is set can be easily detected.

  According to the present invention, the image forming apparatus is developed by a contact method using a one-component developer. According to this example, the mode change process can be performed with a simple configuration in the contact-type image forming apparatus using a one-component developer.

  According to the present invention, in the image forming apparatus, the transfer unit includes an endless belt. According to this example, in an image forming apparatus that uses an endless belt as a transfer device, the mode change process can be performed with a simple configuration.

  According to the present invention, in the image forming apparatus, the endless belt also serves as a paper conveying belt. According to this example, even in an image forming apparatus in which the endless belt also serves as a paper conveyance belt, the mode change process can be performed with a simple configuration.

  According to the present invention, in the image forming apparatus, the driving member having the separation structure is a stepping motor. According to this example, the drive mechanism can be configured with high accuracy and at low cost.

  According to the present invention, in the image forming apparatus, at least a part of members constituting the switching mechanism is made of POM (polyacetal). According to this example, the drive mechanism can be configured at low cost.

  The image forming apparatus according to the embodiment will be described below. FIG. 1 is a schematic diagram illustrating a schematic configuration of an image forming apparatus according to an embodiment. FIG. 2 is a cross-sectional view illustrating an image forming unit of the image forming apparatus according to the embodiment. The image forming apparatus 100 according to this example uses four color toners of yellow (Y), magenta (M), cyan (C), and black (B), and uses the four color toners in the color mode. In the monochrome mode, image formation is performed using the black toner. As shown in FIG. 1, the image forming apparatus 100 includes image forming units 200Y, 200M, 200C, and 200K corresponding to the four colors.

  The image forming apparatus 100 includes an exposure device 110 that writes a latent image on the photosensitive drums 211Y, 211M, 211C, and 211K (see FIG. 2), which are image carriers of the image forming units 200Y, 200M, 200C, and 200K. The toner image formed on the photosensitive drums 211Y, 211M, 211C, and 211K is transferred while transferring the transfer paper, which is a transfer body, the paper tray 130 storing the transfer paper, and transferred to the paper And a fixing device 140 for fixing the toner image.

  The exposure device 110 includes a polygon mirror and an imaging optical system, and irradiates the photosensitive drums 211Y, 211M, 211C, and 211K with a laser beam in a predetermined pattern to form a latent image. The transfer device 120 corresponds to the endless belt-like intermediate transfer body 121 and the image forming units 200Y, 200M, 200C, and 200K arranged so as to be in contact with the photosensitive drums 211Y, 211M, 211C, and 211K. Four transfer rollers 122Y, 122M, 122C, and 122K are provided with 121 therebetween. Further, the image forming apparatus 100 includes a paper feed roller 151, a pair of registration rollers 152 and 153, a toner density sensor 154, a pair of discharge rollers 155, and the like.

  Next, the image forming units 200Y, 200M, 200C, and 200K will be described. In this example, the image forming units 200Y, 200M, 200C, and 200K have the same configuration. For this reason, the basic structure will be described with reference to FIG. 2 without adding subscripts (Y, M, C, K) to the reference numerals. The image forming unit 200 includes a photosensitive unit 210 and a developing unit 220, and the photosensitive unit 210 and the developing unit 220 are arranged so as to be movable in the vertical direction without moving in the paper feeding direction of the transfer device 120. Is done. FIG. 2 shows the boundary between the photosensitive unit 210 and the developing unit 220 with a two-dot chain line.

  The photosensitive unit 210 includes a rotationally driven photosensitive drum 211 (211Y, 211M, 211C, 211K), a charging unit 212 that uniformly charges the surface of the photosensitive drum 211, and a cleaning unit 213 that cleans residual toner. These are configured as a unit. In this example, the photosensitive unit 210 is arranged so as to be movable in the vertical direction without changing its position in the paper transport direction (transfer roller moving direction), and the photosensitive drum 211 is moved up and down by the switching device 300 as a switching mechanism. As a result, the entire photosensitive unit 210 is moved in the vertical direction, and the photosensitive drum 211 is driven so as to be in contact with and separated from the intermediate transfer member 121.

  The developing unit 220 includes a developing roller 221 that applies a developer to the photosensitive drum 211 and develops it, supply rollers 222 and 223 that supply the developer to the developing roller 221, a stirring roller 225 that stirs the developer, and the like. These are configured so that they can move vertically as a unit. In this example, the developing unit 220 is disposed so as to be movable in the vertical direction without changing its position in the paper transport direction (transfer roller moving direction), and the developing roller 221 is moved up and down by the switching device 300 so that the developing unit 220 is entirely moved. Moves up and down, and the developing roller 221 is driven so as to come into contact with and separate from the photosensitive drum 211. Here, as the developing unit, a one-component developer is used and development is performed by a contact method. However, a two-component developer can be used, or another developing method can be adopted.

  In the image forming apparatus 100, the photosensitive drums 211Y, 211M, 211C, and 211K of the image forming units 200Y, 200M, 200C, and 200K are exposed with a predetermined pattern by the exposure device 110, and the photosensitive drums 211Y, 211M, 211C, and 211K are developed. In response to the development by the unit 220, the transfer paper transported from the paper tray 130 by the paper feed roller 151 is transported to the transfer device 120 through the pair of registration rollers 152 and 153, and the transfer device 120 performs the photosensitive drum. The toner is sequentially transferred from 211Y, 211M, 211C, and 211K, fixed by the fixing device 140, and discharged through the discharge roller pair 155.

  Next, the switching device 300 will be described. FIG. 3 is a perspective view showing the driving device according to the embodiment, FIG. 4 is a front view showing the driving device in the color mode, FIG. 5 is a front view showing the driving device in the monochrome mode, and FIG. 6 shows the driving device in the monochrome mode. FIG. 7 is a front view showing the driving device in the jam clearing mode, FIG. 8 is a cross-sectional view showing the driving device in the jam clearing mode, and FIG. 9 is a partially enlarged perspective view of the driving device according to the embodiment. The switching device 300 according to this example includes a position setting member 310 and a driving device 320. In this example, in the image forming apparatus 100, the position setting member 310 and the driving device 320 are driven in the vertical direction by the switching device 300, and are set in three modes: color mode, monochrome, and jam removal mode.

  In the color mode, all the photosensitive drums 211Y, 211M, 211C, 211K are in contact with the intermediate transfer member 121, and all the developing rollers 221Y, 221M, 221C, 221K are in contact with the photosensitive drums 211Y, 211M, 211C, 211K. Thus, image formation in all colors is performed (see FIG. 4).

  In the monochrome mode, all the photosensitive drums 211Y, 211M, 211C, 211K are in contact with the intermediate transfer member 121, the black developing roller 221K is in contact with the photosensitive drum 211K, and the other developing rollers 221Y, 221M, 221C is disposed in a state of being separated from the photosensitive drums 211Y, 211M, and 211C (d1 in FIG. 6) (see FIGS. 5 and 6). As a result, an image is formed only with black.

  In the jam clearing mode, all the photosensitive drums 211Y, 211M, 211C, and 211K are arranged apart from the intermediate transfer member 121 (d2 in FIGS. 7 and 8), and all the developing rollers 221Y, 221M, 221C, 221K moves together with the photosensitive drums 211Y, 211M, 211C, and 211K (see FIGS. 7 and 8).

  The position setting member 310 is disposed so as to be linearly movable in the sheet conveyance direction, and is mounted with the photosensitive drums 211Y, 211M, 211C, and 211K and the developing rollers 221Y, 221M, 221C, and 221K. 211Y, 211M, 211C, 211K and the developing rollers 221Y, 221M, 221C, 221K are moved to predetermined positions. The driving device 320 reciprocates the position setting member 310 in the direction of arrow A in FIG.

  The position setting member 310 is a rod-shaped member, and two of them are arranged as a pair, and support both ends of the photosensitive drums 211Y, 211M, 211C, 211K and the developing rollers 221Y, 221M, 221C, 221K. That is, as shown in FIG. 4, the position setting member 310 is provided with a developing roller mounting surface 311 on the upper side surface on which both ends of the shaft members of the developing rollers 221Y, 221M, 221C, and 221K are mounted. Yes. The developing roller mounting surface 311 is formed with developing roller driving cam surfaces 312Y, 312M, 312C, 312K having a predetermined profile corresponding to the developing rollers 221Y, 221M, 221C, 221K.

  The developing roller drive cam surfaces 312Y, 312M, 312C, 312K are contact portions for bringing the developing rollers 221Y, 221M, 221C, 221K into contact with the photosensitive drums 211Y, 211M, 211C, 211K, and developing rollers 221Y, 221M, 221C, 221K. Are separated from the photoconductive drums 211Y, 211M, 211C, 211K, and an inclined portion that connects the contact portion and the separated portion. FIG. 4B shows an enlarged view of the developing roller driving cam surface 312C. A contact portion 312a, a separating portion 312c, and an inclined portion 312b are formed on the developing roller drive cam surface 312C. Similar profiles are formed on the other developing roller drive cam surfaces 312K, 312Y and 312M.

  Further, as shown in FIGS. 6 and 8, the position setting member 310 is a photosensitive drum in which the shaft member ends of the photosensitive drums 211Y, 211M, 211C, and 211K are arranged in contact with the opposing inner side surfaces. A support portion 313 is formed. As shown in FIGS. 3 to 8, the photosensitive drum support portion 313 has photosensitive drum driving cam surfaces 314Y, 314M, and 314C having a predetermined profile corresponding to the photosensitive drums 211Y, 211M, 211C, and 211K. , 314K are formed. The photosensitive drum driving cam surfaces 314Y, 314M, 314C, and 314K include contact portions that contact the photosensitive drums 211Y, 211M, 211C, and 211K with the intermediate transfer member 121 of the transfer device 120, and photosensitive drums 211Y, 211M, 211C, and 314K. A separation portion that separates 211K from the intermediate transfer member 121, and an inclined portion that connects the contact portion and the separation portion. FIG. 8B shows an enlarged view of the photosensitive drum drive cam surface 314C. A contact portion 314a, a separation portion 314c, and an inclined portion 314b are formed on the photosensitive drum driving cam surface 314C. Similar profiles are formed on the other photosensitive drum drive cam surfaces 314K, 314Y, and 314M.

  Further, as shown in FIG. 9, the position setting member 310 has a rack 315 formed at the end thereof, and position detection protrusions 161, 162, and 163. By detecting these protrusions 161, 162, and 163 with a sensor (not shown), the position of the position setting member 310 is detected, and thereby the mode of the image forming apparatus 100 is determined.

  The driving device 320 transmits the driving force of the stepping motor 321 that is a driving member to the pinion 323 through the gear train 322, and linearly reciprocates the driving device 320 engaged with the pinion 323 in the rack 325. This control is performed in response to a command from a control unit (not shown), and by selecting a desired printing mode or the like, the driving device 320 operates and the position setting member 310 moves forward and backward, so that the image forming apparatus 100 operates in a predetermined mode. Set to

  The position setting member 310 and the gears of the driving device 320 which are members constituting these switching mechanisms can be made of POM (polyacetal), and thus the driving mechanism can be configured at low cost. Also, these materials can be other synthetic resin materials or metal materials.

  In this manner, the position setting member 310 drives the photoconductor unit 210 and the developing unit 220 in the vertical direction according to the designated mode. In each figure, only the photosensitive drum driving cam surfaces 314Y, 314M, 314C, and 314K of the photosensitive unit 210 and the developing roller driving cam surfaces 312Y, 312M, 312C, and 312K of the developing unit 220 are illustrated. The entire photoreceptor unit 210 and developing unit 220 shown in FIG.

  The developing roller driving cam surfaces 312Y, 312M, 312C, 312K and the photosensitive drum driving cam surfaces 314Y, 314M, 314C, 314K are the developing rollers 221Y, 221M, 221C, 221K in the color mode, monochrome mode, and jam removal mode. The shape and position of the developing rollers 221Y, 221M, 221C, and 221K are set so as to be arranged at predetermined positions. Each mode will be described below.

  In the color mode, the driving device 320 pushes the position setting member 310. As shown in FIG. 4, the photosensitive drums 211Y, 211M, 211C, and 211K are positioned at the contact portions of the photosensitive drum driving cam surfaces 314Y, 314M, 314C, and 314K. Further, all the developing rollers 221Y, 221M, 221C, and 221K are located at the contact portions of the developing roller driving cam surfaces 312Y, 312M, 312C, and 312K. Thereby, image formation is performed by all the image forming units 200Y, 200M, 200C, and 200K, and color image formation is performed.

  In the monochrome mode, the driving device 320 moves the position setting member 310 to the left side in the drawing. Then, as shown in FIGS. 5 and 6, the photosensitive drums 211Y, 211M, and 211C are positioned at the separated portions of the photosensitive drum driving cam surfaces 314Y, 314M, and 314C, and the black photosensitive drum 211K is driven by the photosensitive drum. It is located at the contact portion of the cam surface 314K. Further, all the developing rollers 221Y, 221M, 221C, and 221K are located at the contact portions of the developing roller driving cam surfaces 312Y, 312M, 312C, and 312K. By this operation, the black photosensitive drum 211K and the developing roller 221K come into contact with each other to perform black developing processing, and the other developing rollers 221Y, 221M, and 221C are separated from the photosensitive drums 211Y, 211M, and 211C (see FIG. 6, d1), and black image formation is performed by the image forming unit 200K, and monochrome image formation is performed.

  In the jam processing mode, the driving device 320 further moves the position setting member 310 to the left side in the drawing. Then, as shown in FIGS. 7 and 8, the photosensitive drum driving cam surface 314Y is positioned at a separation portion of the photosensitive drum driving cam surfaces 314Y, 314M, 314C, and 314K, and all the photosensitive drums 211Y, 211M, and 211C are located. 211K are separated from the photosensitive drum 211 (d2 in FIGS. 7 and 8). Further, all the developing rollers 221Y, 221M, 221C, 221K are located at the contact portions of the developing roller driving cam surfaces 312Y, 312M, 312C, 312K, and the photosensitive drums 211Y, 211M, 211C, 211K and the developing roller driving cam surface 312Y. , 312M, 312C, 312K are in contact with each other. As a result, gaps (d2 in FIGS. 7 and 8) are formed between the photosensitive drums 211Y, 211M, 211C, and 211K and the intermediate transfer body 121, and the jammed paper can be easily removed.

  As described above, according to the image forming apparatus according to the present example, the mode can be switched by a switching device having a simple configuration. Therefore, the color mode, the monochrome mode, Jam processing mode switching processing can be performed.

100 Image forming device 110 Exposure device 120 Transfer device 121 Intermediate transfer body 122Y, 122M, 122C, 122K Transfer roller 130 Paper tray 140 Fixing device 151 Paper feed roller 152, 153 Registration roller pair 154 Toner density sensor 155 Discharge roller pair 161, 162 , 163 Projection 200Y, 200M, 200C, 200K Image forming unit 210 Photosensitive unit 211Y, 211M, 211C, 211K Photosensitive drum (image carrier)
212 Charging means 213 Cleaning unit 220 Developing unit 221Y, 221M, 221C, 221K Developing roller (developer carrier)
222, 223 Supply roller 225 Stirrer roller 300 Switching device 310 Position setting member 311 Developing roller placement surface 312Y, 312M, 312C, 312K Developing roller driving cam surface 312a Contact portion 312b Inclining portion 312c Separating portion 313 Photosensitive drum support portion 314Y, 314M, 314C, 314K ... Light drum driving cam surface 314a Contact portion 314b Inclining portion 314c Separating portion 315 Rack 320 Driving device (driving means)
321 Stepping motor 322 Gear train 323 Pinion 325 Rack

JP 2003-215880 A JP 2002-268410 A

Claims (9)

A plurality of image carriers on which electrostatic charging images are formed so that the charging means for charging the surface is integrally movable, and the electrostatic latent images are arranged corresponding to the image carriers, and the electrostatic latent images are converted into toner images. In an image forming apparatus comprising: a plurality of developer carriers to be developed as a transfer device; and a transfer device that transfers a toner image on the image carrier to a transfer material.
A switching mechanism having a common position setting member that linearly moves to set each developer carrier and each image carrier in a variable position and a drive unit that linearly moves the position setting member ;
Color mode for color image formation and monochrome mode for monochrome image formation can be set,
In the color mode, the switching mechanism moves the developer carrier to a development position where the corresponding image carrier can be developed,
In the monochrome mode, the switching mechanism places one developer carrier at a development position where the corresponding image carrier can be developed and develops the other image carrier corresponding to the other developer carrier. an image forming apparatus comprising Rukoto moved to non-separated position. The switching mechanism is
A pinion provided in the driving means and driven to rotate;
Positions of the developer carriers and the image carriers that are provided in the position setting member and that support both ends of the rack that engages with the pinion and linearly drives the position setting member and the developer carrier. A direct-acting cam part for changing
The image forming apparatus according to claim 1, further comprising: Can set the jam eliminating mode in order to clear a paper jam,
In the jam elimination mode, the switching mechanism is characterized by causing pre Rutotomoni the Kizo carrier is separated from the transfer device, the front Kigen image-carrying member is moved in accordance with the movement of said image bearing member The image forming apparatus according to claim 1. A sensor for detecting an arrangement state of the position setting member ;
The image forming apparatus according to any one of claims 1 to 3, characterized in that to detect the detected and mode set in the image forming apparatus, the arrangement of the position setting member by the sensor. The image forming apparatus according to any one of claims 4 to Rukoto developed in contact manner using one-component developer the preceding claims, characterized. The transfer device is an image forming apparatus according to any one of claims 1 to 5, characterized in Rukoto comprises an endless belt. The endless belt is an image forming apparatus according to claim 6, characterized that you have also serves as a sheet conveying belt. It said drive means image forming apparatus according to any one of claims 1 to 7, characterized in Oh Rukoto a stepping motor. At least a portion of the image forming apparatus according to any one of claims 1 to 8, wherein to Rukoto and material of POM (polyacetal) of member constituting the switching mechanism.