JP6217559B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus.

  In Patent Document 1, during non-image formation, the secondary transfer roller is pressed against the intermediate transfer belt while forming an electric field in a direction in which the toner returns from the secondary transfer roller to the intermediate transfer belt, and the seam of the intermediate transfer belt is A configuration is disclosed in which the secondary transfer roller is separated when it is at a position facing the secondary transfer roller.

Japanese Patent Laid-Open No. 10-240038

  There is an image forming apparatus that forms an image using toner that has a flat shape by including a flat pigment (for example, aluminum). In this image forming apparatus, a non-transfer image (for example, an image quality adjustment patch) that is not transferred to a recording medium is conveyed by a conveyance body such as an intermediate transfer belt, and the non-transfer image is transferred to the conveyance body and a secondary transfer roll. If the carrier and the transfer member are in contact with each other when passing through the transfer position between the transfer member and the transfer member, the flat toner may pierce the transfer member depending on its posture. When the toner containing the flat pigment pierces the transfer member, the transfer member is damaged.

  The present invention suppresses damage to the transfer member due to the toner containing the flat pigment, as compared with the configuration in which the non-transfer image formed with the toner containing the flat pigment passes through the transfer position and the carrier and the transfer member are in contact with each other. For the purpose.

According to a first aspect of the present invention, there is provided a first forming portion for forming a first non-transfer image that is not transferred to a recording medium with a toner containing a flat pigment and a first transfer image that is transferred to the recording medium, and a flat pigment. A second forming portion that forms a second non-transfer image that is not transferred to the recording medium and a second transfer image that is transferred to the recording medium with toner not included; the first non-transfer image; and the second non-transfer image An image, the first transfer image, and the second transfer image are transferred to a transfer position; the first transfer image and the second transfer image are transferred to a recording medium at the transfer position; and the first non-transfer A transfer member that is separated from the transport body when the image passes through the transfer position, and that contacts the transport body when the second non-transfer image passes through the transfer position .

The invention of claim 2, in contact with the transfer member to rotation, the transfer member removing member for removing foreign matter adhering to, wherein the conveying member, the first non-transfer image and the second in a state where the non-transferred image is shifted in the conveying direction, the first non-transfer image, said second non-transferred image, you conveying the first transferred image and the second transferred image to a transfer position.

  According to a third aspect of the present invention, when the transfer member is applied with a transfer voltage, the first transfer image and the second transfer image are transferred to a recording medium at the transfer position, and the second non-transfer image is When passing through the transfer position, a voltage having a polarity opposite to the transfer voltage is applied, and the carrier is configured to transfer at least one of the first transfer image and the second transfer image, the second non-transfer image, With the first non-transfer image arranged in this order from the upstream in the transport direction, the first non-transfer image, the second non-transfer image, the first transfer image, and the second transfer image are transferred to the transfer position. Transport.

According to a fourth aspect of the present invention, in the first mode, the first non-transferred image that is not transferred to the recording medium and the first transferred image that is transferred to the recording medium are formed with toner containing a flat pigment. The first non-transfer image, the first forming portion that does not form the first transfer image, the second non-transfer image that is not transferred to the recording medium in the second mode, and the second transfer image that is transferred to the recording medium A second forming portion that is formed with toner that does not contain a flat pigment, and transporting the first non-transfer image, the second non-transfer image, the first transfer image, and the second transfer image to a transfer position, A carrier having a transfer area to which the first non-transfer image and the second non-transfer image are transferred; a transfer area to which the first non-transfer image and the second non-transfer image are transferred; 1 non-transfer image, the second non-transfer image, the first transfer image, and the second transfer image. A transport body for transporting an image to a transfer position; and the transport body in the first mode when the first transfer image is transferred to a recording medium at the transfer position and the transfer area passes through the transfer position. A transfer member that is separated from the transfer member and transfers the second transfer image to a recording medium at the transfer position and contacts the carrier when the transfer region passes through the transfer position in the second mode. Prepare.

The invention of claim 5, in contact with the transfer member to rotate, Ru provided with a removing member for removing foreign matter adhering to the transfer member.

  According to the configuration of the first aspect of the present invention, the toner containing the flat pigment is compared with the configuration in which the non-transfer image formed by the toner containing the flat pigment is in contact with the transfer member when the non-transfer image passes through the transfer position. Can prevent damage to the transfer member.

  According to the second aspect of the present invention, toner containing no flat pigment can be supplied as a lubricant between the removing member and the transfer member.

  According to the configuration of the third aspect of the present invention, when the second non-transfer image passes through the transfer position, the switching of the polarity of the voltage and the switching operation of the contact / separation of the transfer member with respect to the conveyance body are performed together. There is no need to do it.

  According to the configuration of the fourth aspect of the present invention, the transfer member is prevented from being damaged by the toner containing the flat pigment as compared with the case where the transfer member contacts the carrier when the transfer region passes the transfer position in the first mode. it can.

  According to the fifth aspect of the present invention, toner containing no flat pigment can be supplied as a lubricant between the removing member and the transfer member.

1 is a schematic diagram illustrating a configuration of an image forming apparatus according to an embodiment as viewed from the front side. FIG. 3 is a schematic diagram illustrating a toner image forming unit according to the embodiment. It is the schematic which shows the partial structure of the transfer apparatus which concerns on this embodiment. In the structure shown in FIG. 3, it is a figure which shows the state which switched the power supply connected to an opposing roll. FIG. 4 is a diagram illustrating a state where the power is turned off and the secondary transfer roll is separated from the transfer belt in the configuration illustrated in FIG. 3. It is the top view and side view of the flat pigment contained in a metal color toner. It is a figure which shows the non-transfer image and transfer image on a transfer belt in a metal color mode. It is a figure which shows the non-transfer image and transfer image on the transfer belt in other color mode. FIG. 4 is a diagram illustrating a posture of a metal color toner on a transfer belt. FIG. 6 is a diagram illustrating a state in which a metal color toner has pierced a secondary transfer roll. FIG. 10 is a diagram illustrating a modification of a position where a non-transferred image is transferred to a transfer belt in the metal color mode. FIG. 10 is a diagram illustrating a modification of a position where a non-transferred image is transferred to a transfer belt in the metal color mode. It is a table | surface which shows an evaluation result.

  Below, an example of an embodiment concerning the present invention is described based on a drawing. In addition, the arrow H shown to each figure shows a perpendicular direction, and the arrow W is a horizontal direction and shows an apparatus width direction.

<Configuration of Image Forming Apparatus 10>
FIG. 1 is a schematic diagram illustrating a configuration of the image forming apparatus 10 as viewed from the front side. As shown in this figure, the image forming apparatus 10 includes an image forming unit 12 that forms an image on a recording medium P such as paper by an electrophotographic method, a transport apparatus 50 that transports the recording medium P, and the image forming apparatus 10. And a control unit 70 for controlling the operation of each unit.

(Transport device 50)
As shown in FIG. 1, the transport device 50 includes a container 51 that stores the recording medium P, and a plurality of transport rolls 52 that transport the recording medium P from the container 51 to the secondary transfer position NT. doing. Further, the transport device 50 includes a plurality of transport belts 58 that transport the recording medium P from the secondary transfer position NT to the fixing device 40, and the recording medium P toward the discharge portion (not shown) of the recording medium P from the fixing device 40. A conveying belt 54 for conveying the toner.

(Image forming unit 12)
The image forming unit 12 includes a toner image forming unit 20 that forms a toner image, a transfer device 30 that transfers the toner image formed by the toner image forming unit 20 to the recording medium P, and a toner image transferred to the recording medium P. And a fixing device 40 that fixes the image to the recording medium P by heating and pressurizing the recording medium P.

  A plurality of toner image forming units 20 are provided so as to form a toner image for each color. In this embodiment, a total of six toner image forming portions 20 of the first special color (V), the second special color (W), yellow (Y), magenta (M), cyan (C), and black (K). Is provided. (V), (W), (Y), (M), (C), and (K) shown in FIG. 1 indicate the colors described above. As the first special color (V) and the second special color (W), for example, a color such as silver or gold is used.

[Toner image forming unit 20]
The toner image forming unit 20 for each color is basically configured in the same manner except for the toner to be used. Specifically, as shown in FIG. 2, each color toner image forming unit 20 includes a photosensitive drum 21 that rotates clockwise in FIG. 2 and a charger 22 that charges the photosensitive drum 21. Have. Further, each color toner image forming unit 20 exposes the photosensitive drum 21 charged by the charger 22 to form an electrostatic latent image on the photosensitive drum 21, and the exposure device 23 uses the photosensitive drum. And a developing device 24 that develops the electrostatic latent image formed on the toner 21 to form a toner image.

[Transfer device 30]
The transfer device 30 primarily transfers the toner image of the photosensitive drum 21 of each color on the transfer belt 31 (intermediate transfer member), and transfers the superimposed toner image onto the recording medium P at the secondary transfer position NT. Next transfer is to be done. Specifically, as illustrated in FIG. 1, the transfer device 30 includes a transfer belt 31 as an example of a conveyance body, a primary transfer roll 33, a secondary transfer roll 34 as an example of a transfer member, and a power feeding unit. 80, a contact / separation mechanism 90 for the secondary transfer roll 34 (see FIG. 3), a cleaning device 60 for the secondary transfer roll 34, and a cleaning device 35 for the transfer belt 31.

[Transfer belt 31]
As shown in FIG. 1, the transfer belt 31 has an endless shape and is wound around a plurality of rolls 32 to determine the posture. In this embodiment, the transfer belt 31 has a reverse obtuse triangular posture that is long in the apparatus width direction when viewed from the front. Among the plurality of rolls 32, the roll 32D shown in FIG. 1 functions as a drive roll that rotates the transfer belt 31 in the arrow A direction by the power of a motor (not shown). The transfer belt 31 circulates in the direction of arrow A, thereby conveying the primary transferred image to the secondary transfer position NT.

  Of the plurality of rolls 32, the roll 32 </ b> T illustrated in FIG. 1 functions as a tension applying roll that applies tension to the transfer belt 31. Among the plurality of rolls 32, the roll 32 </ b> B illustrated in FIG. 1 functions as a counter roll 32 </ b> B of the secondary transfer roll 34. As described above, the top of the lower end side forming the obtuse angle of the transfer belt 31 in the inverted obtuse triangular shape is wound around the opposing roll 32B. The transfer belt 31 is in contact with the photosensitive drum 21 of each color from below at the upper side extending in the apparatus width direction in the above-described posture.

[Primary transfer roll 33]
The primary transfer roll 33 is a roll for transferring the toner image of each photosensitive drum 21 onto the transfer belt 31 and is disposed inside the transfer belt 31 as shown in FIG. Each primary transfer roll 33 is disposed opposite to the corresponding photosensitive drum 21 with the transfer belt 31 in between. Further, a primary transfer voltage having a polarity opposite to the toner polarity is applied to the primary transfer roll 33 by a power feeding unit (not shown). By applying the primary transfer voltage, the toner image formed on the photosensitive drum 21 is transferred to the transfer belt 31 at the primary transfer position T.

[Secondary transfer roll 34]
The secondary transfer roll 34 is a roll that transfers the toner image superimposed on the transfer belt 31 to the recording medium P. As shown in FIG. 3, the secondary transfer roll 34 is disposed so as to sandwich the transfer belt 31 between the secondary transfer roll 34 and the opposing roll 32B, and the secondary transfer roll 34 and the transfer belt 31 have a predetermined load. In contact. A space between the secondary transfer roll 34 and the transfer belt 31 in contact with each other is set as a secondary transfer position NT. The recording medium P is supplied to the secondary transfer position NT from the container 51 in a timely manner. The secondary transfer roll 34 is driven to rotate clockwise in FIG. In the present specification, the position between the secondary transfer roll 34 and the transfer belt 31 including the case where the secondary transfer roll 34 and the transfer belt 31 are separated is referred to as a secondary transfer position NT.

[Power supply unit 80]
As shown in FIG. 3, the power supply unit 80 (application unit) includes a first power source 80A, a second power source 80B, a switch 80S (switching unit), and a contact roll 80C. The contact roll 80 </ b> C is a roll that comes into contact with the opposing roll 32 </ b> B, and is driven to rotate while in contact with the opposing roll 32 </ b> B. The first power supply 80A is a power supply that applies a negative voltage to the opposing roll 32B via the contact roll 80C. The second power supply 80B is a power supply that applies a positive voltage to the opposing roll 32B via the contact roll 80C.

  The switch 80S (switching unit) connects the first power source 80A to the opposing roll 32B via the contact roll 80C (the state shown in FIG. 3), and supplies the second power source 80B to the opposing roll 32B via the contact roll 80C. It can be switched between a connection state (state shown in FIG. 4) and a power-off state (state shown in FIG. 5) in which no power source is connected to the contact roll 80C.

  In the power feeding unit 80, when the toner image on the transfer belt 31 is transferred to the recording medium P, as shown in FIG. 3, the first power source 80A and the opposing roll 32B are connected via the contact roll 80C by the switch 80S. Connected.

  As a result, a negative voltage is applied to the opposing roll 32B, and a potential difference is generated between the opposing roll 32B and the secondary transfer roll 34. That is, when a negative voltage is applied to the counter roll 32B, a secondary transfer voltage (positive voltage) having a polarity opposite to the toner polarity is indirectly applied to the secondary transfer roll 34 that forms the counter electrode of the counter roll 32B. To be applied. As a result, the toner image is transferred from the transfer belt 31 to the recording medium P that passes through the secondary transfer position NT.

  On the other hand, when the toner image on the transfer belt 31 passes through the secondary transfer position NT and the toner image is held on the transfer belt 31, as shown in FIG. The opposing roll 32B is connected via the contact roll 80C.

  As a result, a positive voltage is applied to the opposing roll 32B, and a potential difference is generated between the opposing roll 32B and the secondary transfer roll 34. That is, by applying a positive voltage to the counter roll 32B, a non-transfer voltage (negative voltage) having the same polarity as the toner polarity is indirectly applied to the secondary transfer roll 34 that forms the counter electrode of the counter roll 32B. Applied. As a result, the toner image passing through the secondary transfer position NT receives a repulsive force from the secondary transfer roll 34 and is held on the transfer belt 31.

  Further, in the power supply unit 80, when the secondary transfer roll 34 is separated from the transfer belt 31 by the contact / separation mechanism 90 as described later, the switch 80S is turned off as shown in FIG.

[Contact / separation mechanism 90]
The contact / separation mechanism 90 is a mechanism that makes the secondary transfer roll 34 contact and separate from the transfer belt 31. Specifically, the contact / separation mechanism 90 moves the support member that rotatably supports the secondary transfer roll 34 in the vertical direction by using a rotationally driven cam, for example, so that the transfer belt 31 is moved. Contact and separate. In addition, as a contact / separation mechanism, the structure using another mechanism element may be sufficient.

[Cleaning device 60 for secondary transfer roll 34]
The transfer device 30 includes a cleaning device 60 that cleans the secondary transfer roll 34. The cleaning device 60 is a removing member that contacts the rotating secondary transfer roll 34 and removes foreign matter (toner or powder of the recording medium P) adhering to the surface of the secondary transfer roll 34 from the secondary transfer roll 34. Consists of blades.

[Cleaning device 35 of transfer belt 31]
As shown in FIG. 1, the cleaning device 35 is disposed downstream of the secondary transfer position NT and upstream of the primary transfer position T (V) in the circumferential direction of the transfer belt 31. The cleaning device 35 includes a blade 351 that scrapes off toner remaining on the surface of the transfer belt 31 from the surface of the transfer belt 31.

<Main part configuration>
Here, in the present embodiment, the toner image forming unit 20V as an example of the first forming unit is configured to form a toner image using silver toner as the second special color (V) (FIG. 1). Further, the toner image forming unit 20W as an example of the first forming unit is configured to form a toner image using gold toner as the second special color (W) (see FIG. 1).

  As shown in FIG. 9, the silver toner 100 used in the toner image forming unit 20 </ b> V includes a flat-shaped flat pigment 110 and a binder resin 111. The gold toner used in the toner image forming unit 20W includes a flat pigment 110, a yellow pigment, and a binder resin 111.

  The flat pigment 110 is made of a metal material such as aluminum, for example. Then, when the flat pigment 110 is placed on a flat surface and viewed from the side, the flat pigment 110 has a longer dimension in the horizontal direction in the figure than the vertical dimension in the figure, as shown in FIG. 6B. It is a shape. The flat pigment 110 has a dimensional ratio between the dimension in the left-right direction and the dimension in the vertical direction larger than the dimensional ratio in the pigment of other color toner described later.

  Further, when the flat pigment 110 shown in FIG. 6B is viewed from above in the drawing, the flat pigment 110 has a shape that is wider than the shape viewed from the side, as shown in FIG. 6A. The flat pigment 110 has a pair of reflective surfaces 110A facing upward and downward with the flat pigment 110 placed on a flat surface (see FIG. 6B). In this way, the flat pigment 110 has a flat shape. In addition, the toner containing the flat pigment 110 has a flat shape as a toner shape.

  In the present specification, for convenience of explanation, silver (V) and gold (W) are referred to as “metal color”, and metal toner is referred to as “metal color toner”. In the figure, when distinguishing between silver (V) and gold (W), reference numerals (V) and (W) are attached.

  The toner images formed by the toner image forming units 20V and 20W include a transfer image (an example of a first transfer image) transferred to the recording medium P and a non-transfer image (a first non-transfer image of the first non-transfer image) that is not transferred to the recording medium P. An example).

  Examples of the non-transfer image include a density detection image (patch) for detecting the toner density of the toner image on the transfer belt 31 (an example of a conveyance body), and a positional shift between colors in the toner image on the transfer belt 31. There are color misregistration detection images (patches) for detecting color, images (bands) for consuming deteriorated developer (toner), and the like.

  Hereinafter, for convenience of explanation, the non-transfer images formed by the toner image forming units 20V and 20W are referred to as “metal color patches”, and the transfer images formed by the toner image forming units 20V and 20W are referred to as “metal color images”.

  In the present embodiment, the detection unit (sensor) 49 for detecting the density detection image (patch) and the color misregistration detection image (patch) is downstream of the toner image forming unit 20K (left side in FIG. 1). ).

  On the other hand, yellow (Y), magenta (M), cyan (C), and black used in toner image forming units 20Y, 20M, 20C, and 20K (hereinafter referred to as 20Y to 20K) as examples of the second forming unit. The toner (K) does not include the flat pigment 110 but includes a pigment other than the flat pigment 110 and a binder resin.

  In this specification, for convenience of explanation, yellow (Y), magenta (M), cyan (C), and black (K) are referred to as “other colors”, and other color toners are referred to as “other color toners”. Called. In the drawing, in order to distinguish yellow (Y), magenta (M), cyan (C), and black (K), reference numerals (Y), (M), (C), and (K) are attached.

  The toner images formed by the toner image forming units 20Y to 20K include a transfer image (an example of a second transfer image) transferred to the recording medium P and a non-transfer image (a second non-transfer image of the second non-transfer image) that is not transferred to the recording medium P. An example). The non-transfer image includes a density detection image (patch), a color misregistration detection image (patch), and a deteriorated developer (toner), similarly to the non-transfer images formed by the toner image forming units 20V and 20W. There are images (bands) for consumption.

  Hereinafter, for convenience of explanation, the non-transfer images formed by the toner image forming units 20Y to 20K are referred to as “other color patches”, and the transfer images formed by the toner image forming units 20Y to 20K are referred to as “other color images”.

  As shown in FIG. 7, the metal color patch 410 and the other color patch 420 are a non-transfer image area between the transfer image area R1 to which the metal color image 310 and the other color image 320 on the transfer belt 31 are transferred. Transferred to R2 (an example of a transfer region). The metal color image 310 and the other color image 320 in the transfer image region R1 pass through the secondary transfer position NT together with the recording medium P, and the metal color image 310 and the other color image 320 are transferred to the recording medium P. On the other hand, the metal color patch 410 and the other color patch 420 in the non-transfer image area R2 do not pass through the secondary transfer position NT together with the recording medium P, but pass through the secondary transfer position NT alone. The transfer image region R1 and the non-transfer image region R2 may be configured such that the position on the transfer belt 31 may be changed or not changed every time the transfer belt 31 rotates.

  Furthermore, in the present embodiment, a mode in which a toner image with at least one of the other color toners is formed on the recording medium P without forming a toner image with the metal color toner on the recording medium P (another color mode), and a metal color And a mode (metal color mode) in which a toner image by at least one toner and a toner image by at least one other color toner are formed on the recording medium P.

  The other color mode (an example of the second mode) is executed when the control unit 70 does not operate the toner image forming units 20V and 20W and operates at least one of the toner image forming units 20Y to 20K. By operating at least one of the toner image forming units 20Y to 20K, the other color image 320 is transferred to each transfer image region R1 of the transfer belt 31 and the other color patch 420 is transferred to the transfer belt, as shown in FIG. 31 is transferred to each non-transferred image region R2. FIG. 8 illustrates a case where all of the toner image forming units 20Y to 20K are activated.

  In the other color mode, the control unit 70 controls the power supply unit 80 and a voltage is applied to the secondary transfer roll 34 as described below. That is, as shown in FIG. 3, when the transfer image region R1 (other color image 320) passes through the secondary transfer position NT, the first power supply 80A and the opposing roll 32B are connected via the contact roll 80C. Then, a secondary transfer voltage (positive voltage) is applied to the secondary transfer roll 34 via the opposing roll 32B. Further, when the non-transfer image area R2 (the other color patch 420) passes through the secondary transfer position NT, as shown in FIG. 4, the second power supply 80B and the opposing roll 32B are connected via the contact roll 80C. Then, a non-transfer voltage (negative voltage) is applied to the secondary transfer roll 34 via the opposing roll 32B.

  Further, in the other color mode, the controller 70 controls the contact / separation mechanism 90 to maintain the state where the secondary transfer roll 34 is in contact with the transfer belt 31 (see FIGS. 3 and 4).

  On the other hand, the metal color mode (an example of the first mode) is executed when the control unit 70 operates at least one of the toner image forming units 20V and 20W and at least one of the toner image forming units 20Y to 20K. By operating at least one of the toner image forming units 20V and 20W and at least one of the toner image forming units 20Y to 20K, the metal color image 310 and the other color image 320 are transferred to the transfer belt 31 as shown in FIG. The metal color patch 410 and the other color patch 420 are transferred to each non-transfer image area R2 of the transfer belt 31 after being transferred to each transfer image area R1. More specifically, in the non-transfer image area R2, the other color patch 420 and the metal color patch 410 are transferred in this order in the state of being arranged from the upstream in the transport direction of the transfer belt 31. FIG. 7 illustrates a case where all of the toner image forming units 20Y to 20K and the toner image forming units 20V and 20W are activated.

In the metal color mode, the control unit 70 controls the power supply unit 80 and a voltage is applied to the secondary transfer roll 34 as described below. That is, when the transfer image region R1 (the metal color image 310 and the other color image 320) passes through the secondary transfer position NT, as shown in FIG. 3, the first power source 80A and the opposing roll 32B are brought into contact rolls 80C. The secondary transfer voltage (positive voltage) is applied to the secondary transfer roll 34 via the opposing roll 32B.
Further, when the other color patch 420 in the non-transfer image area R2 passes through the secondary transfer position NT, as shown in FIG. 4, the second power supply 80B and the opposing roll 32B are connected via the contact roll 80C. Then, a non-transfer voltage (negative voltage) is applied to the secondary transfer roll 34 via the opposing roll 32B.
Further, when the metal color patch 410 in the non-transfer image area R2 passes the secondary transfer position NT, as shown in FIG. 5, the switch 80S is turned off, and the power supply by the power supply unit 80 is stopped. To do.

  Further, in the metal color mode, the control unit 70 controls the contact / separation mechanism 90 to bring the secondary transfer roll 34 into contact with or separate from the transfer belt 31 as described below. That is, as shown in FIGS. 3 and 4, when the other color patch 420 in the transfer image region R1 and the non-transfer image region R2 passes the secondary transfer position NT, the secondary transfer roll 34 is moved to the transfer belt 31. Contact. Further, when the metal color patch 410 in the non-transfer image area R2 passes through the secondary transfer position NT, the transfer belt 31 is separated from the secondary transfer roll 34 as shown in FIG.

(Operation according to this embodiment)
Next, the operation according to this embodiment will be described.

(Other color mode)
When the control unit 70 receives an image formation command (print command) in the other color mode, the control unit 70 operates the toner image forming units 20Y to 20K of other colors, the transfer device 30, and the fixing device 40 (see FIG. 1). ).

  Thus, in the toner image forming units 20Y to 20K, the other color image 320 (see FIG. 8) and the other color patch 420 (see FIG. 8) are formed in the following image forming process (process). That is, the photosensitive drums 21 of the respective colors are charged by the charger 22 while being rotated. Each charged photosensitive drum 21 is exposed by each exposure device 23, and an electrostatic latent image is formed on the surface of each photosensitive drum 21. The electrostatic latent image formed on each photoconductor drum 21 is developed by the developer supplied from the developing device 24. Thus, the other color image 320 and the other color patch 420 of yellow (Y), magenta (M), cyan (C), and black (K) are formed on the photosensitive drums 21 of the respective colors.

  As shown in FIG. 8, the other color image 320 of each color formed on the photosensitive drum 21 of each color is sequentially transferred to the transfer image region R <b> 1 of the rotating transfer belt 31 by the primary transfer roll 33 of each color. The other color patches 420 of the respective colors formed on the photosensitive drums 21 of the respective colors are sequentially transferred to the non-transferred image region R2 of the rotating transfer belt 31 by the primary transfer rolls 33 of the respective colors. As a result, the other color image 320 and the other color patch 420 transferred to the transfer belt 31 are conveyed to the secondary transfer position NT by the rotation of the transfer belt 31.

  The recording medium P is supplied to the secondary transfer position NT in synchronization with the conveyance of the other color image 320 by the conveyance roll 52. When the recording medium P and the transfer image region R1 (other color image 320) pass through the secondary transfer position NT, the secondary transfer roll 34 is transferred to the transfer belt 31 by the contact / separation mechanism 90 as shown in FIG. The state in contact with is maintained. Further, at this time, the first power supply 80A and the opposing roll 32B are connected via the contact roll 80C, and a secondary transfer voltage (positive voltage) is applied to the secondary transfer roll 34 via the opposing roll 32B. . As a result, the other color image 320 is transferred from the transfer belt 31 to the recording medium P.

  The recording medium P to which the other color image 320 has been transferred is conveyed from the secondary transfer position NT to the fixing device 40 by the conveying belt 58, and the other color image 320 on the recording medium P is transferred to the recording medium P in the fixing device 40. It is fixed.

  Also, when the non-transferred image region R2 (the other color patch 420) passes through the secondary transfer position NT without passing through the recording medium P, as shown in FIG. The state where the transfer roll 34 is in contact with the transfer belt 31 is maintained. Further, at this time, the second power supply 80B and the opposing roll 32B are connected via the contact roll 80C, and a non-transfer voltage (negative voltage) is applied to the secondary transfer roll 34 via the opposing roll 32B. Accordingly, the other color patch 420 on the transfer belt 31 receives a repulsive force from the secondary transfer roll 34 and is held by the transfer belt 31. Thus, the other color toner of the other color patch 420 is conveyed to the cleaning device 35 through the secondary transfer position NT while being held on the transfer belt 31, and is removed from the transfer belt 31 by the cleaning device 35.

  Since the secondary transfer roll 34 and the transfer belt 31 are in contact with each other with a predetermined load, a part of the other color toner of the other color patch 420 may receive an electrostatic repulsive force. Transferred to the secondary transfer roll 34. The other color toner transferred to the secondary transfer roll 34 is conveyed to the cleaning device 60 by the rotation of the secondary transfer roll 34, and is removed from the secondary transfer roll 34 by the cleaning device 60. Part of the other color toner conveyed to the cleaning device 60 is supplied as a lubricant between the cleaning device 60 and the secondary transfer roll 34.

(Metal color mode)
When the control unit 70 receives an image formation command (print command) in the metal color mode, the control unit 70 displays the metal color toner image forming units 20V and 20W, the other color toner image forming units 20Y to 20K, and the transfer device 30. Then, the fixing device 40 is operated (see FIG. 1).

  Thus, in the toner image forming units 20V and 20W, the metal color image 310 and the metal color patch 410 are formed on each photosensitive drum 21 through the same image forming process (process) as described above. In the toner image forming units 20 </ b> Y to 20 </ b> K, the other color image 320 and the other color patch 420 are formed on each photosensitive drum 21 through the same image forming process (process) as described above.

  As shown in FIG. 7, the other color image 320 and the metal color image 310 of each color formed on each photoconductive drum 21 are transferred to the transfer image region R1 of the transfer belt 31 that is circulated by the primary transfer roll 33 of each color. Are sequentially transferred.

  The color patches 410 of the respective colors formed on the respective photoconductive drums 21 are sequentially transferred to the downstream side in the transport direction in the non-transfer image area R2 of the rotating transfer belt 31 by the primary transfer rolls 33 of the respective colors. The other color patches 420 formed on the respective photosensitive drums 21 are sequentially transferred to the upstream side in the transport direction in the non-transfer image area R2 of the rotating transfer belt 31 by the primary transfer roll 33 of each color.

  Then, the other color patch 420, the metal color patch 410, the other color image 320, and the metal color image 310 are secondary by the rotation of the transfer belt 31 in a state where the other color patch 420 and the metal color patch 410 are shifted in the transport direction. It is conveyed to the transfer position NT.

  The recording medium P is supplied to the secondary transfer position NT in synchronization with the transport of the other color image 320 and the metal color image 310 by the transport roll 52. When the recording medium P, the other color image 320 and the metal color image 310 (transfer image region R1) pass through the secondary transfer position NT, as shown in FIG. The state where 34 is in contact with the transfer belt 31 is maintained. Further, at this time, the first power supply 80A and the opposing roll 32B are connected via the contact roll 80C, and a secondary transfer voltage (positive voltage) is applied to the secondary transfer roll 34 via the opposing roll 32B. . As a result, the other color image 320 and the metal color image 310 are transferred from the transfer belt 31 to the recording medium P.

  The recording medium P to which the other color image 320 and the metal color image 310 have been transferred is transported from the secondary transfer position NT to the fixing device 40 by the transport belt 58, and the other color image 320 on the recording medium P is transferred by the fixing device 40. Is fixed to the recording medium P.

  Even when the recording medium P does not pass through the secondary transfer position NT but the other color patch 420 passes, the secondary transfer roll 34 contacts the transfer belt 31 by the contact / separation mechanism 90 as shown in FIG. Maintained. Further, at this time, the second power supply 80B and the opposing roll 32B are connected via the contact roll 80C, and a non-transfer voltage (negative voltage) is applied to the secondary transfer roll 34 via the opposing roll 32B. Accordingly, the other color patch 420 on the transfer belt 31 receives a repulsive force from the secondary transfer roll 34 and is held by the transfer belt 31. Thus, the other color toner of the other color patch 420 is conveyed to the cleaning device 35 through the secondary transfer position NT while being held on the transfer belt 31, and is removed from the transfer belt 31 by the cleaning device 35.

  Since the secondary transfer roll 34 and the transfer belt 31 are in contact with each other with a predetermined load, a part of the other color toner of the other color patch 420 may receive an electrostatic repulsive force. Transferred to the secondary transfer roll 34. The other color toner transferred to the secondary transfer roll 34 is conveyed to the cleaning device 60 by the rotation of the secondary transfer roll 34, and is removed from the secondary transfer roll 34 by the cleaning device 60. Part of the other color toner conveyed to the cleaning device 60 is supplied as a lubricant between the cleaning device 60 and the secondary transfer roll 34.

  On the other hand, when the recording medium P does not pass through the secondary transfer position NT but the metal color patch 410 passes, the secondary transfer roll 34 is moved by the contact / separation mechanism 90 as shown in FIG. Spaced apart. Further, at this time, the switch 80S is turned off, and the power supply by the power supply unit 80 is stopped. Accordingly, the other color patch 420 on the transfer belt 31 is conveyed to the cleaning device 35 while being held by the transfer belt 31, and is removed from the transfer belt 31 by the cleaning device 35.

  Here, the metal color toner 100 of the metal color patch 410 on the transfer belt 31 is charged on the transfer belt 31 after passing the primary transfer position T due to the flat shape as shown in FIG. It is localized and easily stands on the transfer belt 31.

  For this reason, in the comparative example in which the metal color patch 410 passes through the secondary transfer position NT with the secondary transfer roll 34 and the transfer belt 31 in contact with each other, as shown in FIG. The secondary transfer roll 34 may be easily pierced, and the surface layer 34A of the secondary transfer roll 34 may be damaged.

  On the other hand, in the present embodiment, the secondary transfer roll 34 is separated from the transfer belt 31 when the metal color patch 410 passes through the secondary transfer position NT. For this reason, the metal color toner does not pierce the secondary transfer roll 34, and damage to the surface layer 34A of the secondary transfer roll 34 is suppressed. Therefore, the formation failure of the electric field due to the low resistance due to the damage of the secondary transfer roll 34 is suppressed, and the image quality failure due to the formation failure of the electric field is suppressed.

  In this embodiment, as shown in FIG. 7, the other color patch 420 is arranged on the upstream side in the transport direction in the non-transfer image area R <b> 2 of the transfer belt 31, and the non-transfer image area R <b> 2 of the transfer belt 31. A metal color patch 410 is disposed on the downstream side in the transport direction.

  On the other hand, the metallic color patch 410 is arranged on the upstream side in the conveyance direction in the non-transfer image area R2 of the transfer belt 31, and the other color patch 420 is arranged on the downstream side in the conveyance direction in the non-transfer image area R2 of the transfer belt 31. In this case, when the other color patch 420 passes through the secondary transfer position NT, the secondary transfer roll 34 is switched from the separated state to the contact state with respect to the transfer belt 31, and the voltage applied to the secondary transfer roll 34 is set to the secondary transfer roll 34. It is necessary to switch from the transfer voltage to the non-transfer voltage.

  On the other hand, in this embodiment, when the other color patch 420 passes through the secondary transfer position NT, the secondary transfer roll 34 is kept in contact with the transfer belt 31 while maintaining the contact state of the secondary transfer roll 34. The voltage to be applied is switched from the secondary transfer voltage to the non-transfer voltage. That is, the switching operation from the secondary transfer voltage to the non-transfer voltage may be performed without performing the operation of switching the secondary transfer roll 34 from the separated state to the contact state with respect to the transfer belt 31.

  That is, in this embodiment, there is no need to perform the operation of switching the secondary transfer roll 34 from the separated state to the contact state with respect to the transfer belt 31 and the operation of switching from the secondary transfer voltage to the non-transfer voltage, and the secondary transfer Responsiveness of the switching operation performed when the other color patch 420 passes through the position NT is improved.

  In this embodiment, a part of the other color toner of the other color patch 420 on the transfer belt 31 is transferred to the secondary transfer roll 34, and the lubricant is provided between the cleaning device 60 and the secondary transfer roll 34. Supplied as For this reason, the deformation | transformation of the cleaning apparatus 60 comprised with the braid | blade etc. is suppressed and deterioration of the cleaning apparatus 60 is suppressed.

(First modification)
In the present embodiment, as shown in FIG. 7, the other color patch 420 is transferred to the upstream side in the transport direction in the non-transfer image area R <b> 2 of the transfer belt 31, and the transport direction in the non-transfer image area R <b> 2 of the transfer belt 31. Although the metal color patch 410 is transferred downstream, the present invention is not limited thereto. For example, as shown in FIG. 11, one of the other color patch 420 and the metal color patch 410 may be transferred for each non-transfer image region R <b> 2 of the transfer belt 31. In this configuration, the other color patch 420 and the metal color patch 410 are alternately transferred to the non-transfer image region R2 of the transfer belt 31, for example. Even in this configuration, the other color patch 420 and the metal color patch 410 are transported to the secondary transfer position NT in a state of being shifted in the transport direction of the transfer belt 31.

  Also in the first modification, for example, the contact / separation mechanism 90 and the power feeding unit 80 are operated as follows. That is, when the other color image 320 and the metal color image 310 (transfer image region R1) pass through the secondary transfer position NT, the secondary transfer roll 34 is transferred by the contact / separation mechanism 90 as shown in FIG. The state in contact with the belt 31 is maintained. Further, at this time, a secondary transfer voltage (positive voltage) is applied to the secondary transfer roll 34 via the opposing roll 32B. As a result, the other color image 320 and the metal color image 310 are transferred from the transfer belt 31 to the recording medium P.

  Further, also when the other color patch 420 passes through the secondary transfer position NT without passing through the recording medium P, the secondary transfer roll 34 is moved by the contact / separation mechanism 90 as shown in FIG. The state in contact with is maintained. Furthermore, at this time, a non-transfer voltage (negative voltage) is applied to the secondary transfer roll 34 via the opposing roll 32B.

  When the recording medium P does not pass through the secondary transfer position NT but the metal color patch 410 passes, the secondary transfer roll 34 is moved by the contact / separation mechanism 90 as shown in FIG. Spaced apart. Further, at this time, the switch 80S is turned off, and the power supply by the power supply unit 80 is stopped.

(Second modification)
In the present embodiment, in the metal color mode, when the other color patch 420 in the non-transfer image area R2 passes through the secondary transfer position NT, the secondary transfer roll 34 is brought into contact with the transfer belt 31, and the secondary transfer position 34 Although the secondary transfer roll 34 is separated from the transfer belt 31 when the metal color patch 410 in the non-transfer image area R2 passes through the transfer position NT, the present invention is not limited to this.

  For example, when the control unit 70 receives an image formation command (print command) in the metal color mode, the secondary transfer position NT is set on the transfer belt 31 regardless of the non-transfer image formed in the non-transfer image region R2. When the non-transfer image region R2 passes, the secondary transfer roll 34 may be separated from the transfer belt 31 by the contact / separation mechanism 90 as shown in FIG. 5 (see FIG. 12). Further, at this time, for example, the switch 80S is turned off, and the power supply by the power supply unit 80 is stopped.

  In this configuration, there are no restrictions on the positions where the metal color patch 410 and the other color patch 420 are transferred in the non-transfer image area R2, and the metal color patch 410 and the other color patch 420 are moved in the transport direction as shown in FIG. No need to shift to

(Third Modification)
In the present embodiment, in the metal color mode, the other color image 320 and the other color patch 420 are formed using the other color toner. However, in the metal color mode, the other color image 320 and the other color using the other color toner are formed. The patch 420 may not be included. In this case, the control unit 70 does not operate the toner image forming units 20Y to 20K, and operates at least one of the toner image forming units 20V and 20W. By operating at least one of the toner image forming units 20V and 20W, the metal color image 310 is transferred to each transfer image region R1 of the transfer belt 31, and the metal color patch 410 is transferred to each non-transfer image region R2 of the transfer belt 31. Is transferred to.

  Also in this configuration, for example, the contact / separation mechanism 90 and the power feeding unit 80 are operated as follows. That is, when the transfer image area R1 passes through the secondary transfer position NT, a secondary transfer voltage (positive voltage) is applied to the secondary transfer roll 34 via the opposing roll 32B, and the non-transfer image area R2 is When passing through the secondary transfer position NT, for example, the power supply by the power supply unit 80 is stopped.

  Further, in this case, when the transfer image region R1 passes the secondary transfer position NT, the secondary transfer roll 34 is brought into contact with the transfer belt 31, and when the non-transfer image region R2 passes the secondary transfer position NT. In addition, the transfer belt 31 is separated from the secondary transfer roll 34.

(Other variations)
In this embodiment, as shown in FIG. 7, the other color patch 420 is arranged on the upstream side in the transport direction in the non-transfer image area R <b> 2 of the transfer belt 31, and the non-transfer image area R <b> 2 of the transfer belt 31. Although the metal color patch 410 is disposed on the downstream side in the transport direction, the present invention is not limited to this. For example, the metal color patch 410 is disposed on the upstream side in the transport direction in the non-transfer image region R2 of the transfer belt 31, and the other color patch 420 is disposed on the downstream side in the transport direction in the non-transfer image region R2 of the transfer belt 31. It may be a configuration.

  In the present embodiment, the secondary transfer roll 34 is used as an example of the transfer member, but the transfer member may be, for example, a secondary transfer belt.

  In this embodiment, the transfer belt 31 is used as an example of the transport body. However, the transport body may be a transfer drum, for example.

  In this embodiment, the secondary transfer voltage, the non-transfer voltage, and the AC voltage are applied to the secondary transfer roll 34 via the opposing roll 32B. However, the present invention is not limited to this, and the secondary transfer roll 34 is directly applied to the secondary transfer roll 34. Various voltages may be applied. In this case, a voltage having a reverse polarity to the voltage applied to the opposing roll 32B is applied to the secondary transfer roll 34.

  In this embodiment, a configuration in which a lubricant (for example, ZnSt) is supplied to the secondary transfer roll 34 to form a lubricant film on the secondary transfer roll 34 may be applied. According to this configuration, even when the metal color toner standing on the transfer belt 31 passes through the secondary transfer position NT, the tip of the metal color toner tends to slip and lie down on the secondary transfer roll 34. Further, the secondary transfer roll 34 is prevented from being pierced.

  In the present embodiment, the surface roughness of the secondary transfer roll 34 may be set to Rz = 2 μm or less. According to this configuration, even when the metal color toner standing on the transfer belt 31 passes through the secondary transfer position NT, the tip of the metal color toner tends to slip and lie down on the secondary transfer roll 34. Further, the secondary transfer roll 34 is prevented from being pierced.

(Evaluation)
In this evaluation, image quality evaluation by continuous paper feeding was performed (room temperature 10 ° C., relative humidity 15%). In the image quality evaluation, “○” indicates that there is no problem in the image quality in the transferred image formed on the sheet as the recording medium P, and “X” indicates that there is a white spot.

Example 1
In the image forming apparatus 10 described above, the following transfer belt 31, counter roll 32B, and secondary transfer roll 34 were used.
Transfer belt 31: volume resistivity 10 [log Ω · cm], thickness 80 [um],
Opposing roll 32B: φ20, volume resistance 6.5 [logΩ], hardness 65 ° (Asker C),
Secondary transfer roll 34: φ24, volume resistance 7.0 [logΩ], hardness 75 ° (Asker C)

  In the non-transfer image area R2 (inter-image), as shown in FIG. 7, a toner patch 20 mm × 20 mm for adjusting image quality as the other color patch 420 is transferred upstream in the transport direction, and metal is transported downstream in the transport direction. A toner patch 20 mm × 20 mm for adjusting image quality as a color patch 410 was transferred. A specific other color image 320 and a metal color image 310 were transferred to the transfer image region R1. The process speed of the image forming apparatus 10 was set to 440 mm / s.

  In the metal color mode, when the transfer image region R1 passes through the secondary transfer position NT, the secondary transfer roll 34 is kept in contact with the transfer belt 31 via the opposing roll 32B while maintaining the contact state of the secondary transfer roll 34. A secondary transfer voltage (positive voltage) was applied. The voltage applied to the facing roll 32B is set to -2 kV.

  Further, in the metal color mode, when the other color patch 420 passes through the secondary transfer position NT, the secondary transfer roll 34B is kept in contact with the transfer belt 31 while maintaining the contact state of the secondary transfer roll 34 with the opposing roll 32B. A non-transfer voltage (negative voltage) was applied to the roll 34. The voltage applied to the facing roll 32B is +0.8 kV.

  Further, in the metal color mode, when the metal color patch 410 passes through the secondary transfer position NT, the secondary transfer roll 34 is separated from the transfer belt 31 and power supply by the power supply unit 80 is stopped.

(Example 2)
In the metallic color mode, the secondary transfer roll 34 is in contact with the transfer belt 31 via the opposing roll 32B when the transfer image region R1 passes through the secondary transfer position NT in the metal color mode. While maintaining the above, a secondary transfer voltage (positive voltage) was applied to the secondary transfer roll 34 via the opposing roll 32B. The voltage applied to the facing roll 32B is set to -2 kV.

  Further, in the metal color mode, when the non-transfer image area R2 passes through the secondary transfer position NT, the secondary transfer roll 34 is separated from the transfer belt 31, and the power supply by the power supply unit 80 is stopped.

(Comparative Example 1)
In the metal color mode, when the transfer image region R1 passes through the secondary transfer position NT, the opposite configuration is maintained while maintaining the contact state of the secondary transfer roll 34 with the transfer belt 31 in the metal color mode. A secondary transfer voltage (positive voltage) was applied to the secondary transfer roll 34 via the roll 32B. The voltage applied to the facing roll 32B is set to -2 kV.

  Further, in the metal color mode, when the non-transferred image region R2 passes through the secondary transfer position NT, the secondary transfer roll 34 is kept in contact with the transfer belt 31 while maintaining the contact state with the secondary roll 32B. A non-transfer voltage (negative voltage) was applied to the transfer roll 34. The voltage applied to the facing roll 32B is +0.8 kV.

  As a result of evaluating Examples 1 and 2 and Comparative Example 1, as shown in FIG. 13, in Examples 1 and 2, there was no problem in image quality even when 500000 sheets were passed. On the other hand, in the comparative example, white spots occurred after 100,000 sheets were passed. Note that the white spots are caused by the resistance of the secondary transfer roll 34 being lowered due to the metal toner sticking into the secondary transfer roll 34 and damaging the surface layer 34A of the secondary transfer roll 34. It is speculated that this will occur.

  The present invention is not limited to the above-described embodiment, and various modifications, changes, and improvements can be made without departing from the spirit of the present invention. For example, the modification examples described above may be appropriately combined.

10 Image forming apparatus 20V, 20W toner image forming unit (an example of a forming unit, an example of a first forming unit)
20Y, 20M, 20C, 20K toner image forming unit (an example of a second forming unit)
31 Transfer belt (an example of a carrier)
34 Secondary transfer roll (an example of a transfer member)
60 Cleaning device (an example of a removal member)

Claims (5)

A first forming portion that forms a first non-transfer image that is not transferred to a recording medium with a toner containing a flat pigment, and a first transfer image that is transferred to the recording medium;
A second forming portion that forms a second non-transfer image that is not transferred to the recording medium with a toner that does not contain a flat pigment, and a second transfer image that is transferred to the recording medium;
A transport body for transporting the first non-transfer image, the second non-transfer image, the first transfer image, and the second transfer image to a transfer position;
The first transfer image and the second transfer image are transferred to a recording medium at the transfer position, and separated from the carrier when the first non-transfer image passes through the transfer position, and the second non-transfer image A transfer member that comes into contact with the transport body when passing through the transfer position ;
An image forming apparatus. In contact with the transfer member to rotation, removing member for removing foreign matter adhering to the transfer member,
With
The carrier is
The first non-transfer image, the second non-transfer image, the first transfer image, and the second transfer image are transferred in a state where the first non-transfer image and the second non-transfer image are shifted in the transport direction. It conveyed to the position,
The image forming apparatus according to 請 Motomeko 1. The transfer member is
When the transfer voltage is applied, the first transfer image and the second transfer image are transferred to a recording medium at the transfer position, and the transfer voltage is applied when the second non-transfer image passes the transfer position. Is applied with a reverse polarity voltage,
The carrier is
In a state where at least one of the first transfer image and the second transfer image, the second non-transfer image, and the first non-transfer image are arranged in this order from the upstream in the transport direction, the first non-transfer image, The image forming apparatus according to claim 2, wherein the second non-transfer image, the first transfer image, and the second transfer image are conveyed to the transfer position. In the first mode, a first non-transfer image that is not transferred to the recording medium and a first transfer image that is transferred to the recording medium are formed with toner containing a flat pigment. In the second mode, the first non-transfer image And a first forming portion that does not form the first transfer image,
A second forming unit that forms, in the second mode, a second non-transferred image that is not transferred to the recording medium and a second transferred image that is transferred to the recording medium with toner containing no flat pigment ;
Has a transfer region where pre-Symbol first non-transfer image and the second non-transferred image is transferred, the first non-transfer image, said second non-transfer image, said first transfer image and the second transferred image A transport body for transporting to a transfer position;
In the first mode, the said first transfer image at the transfer position and transferred onto the recording medium, and, apart from the carrier when the transfer area passes through the transfer position, in said second mode, said A transfer member that transfers the second transfer image to a recording medium at a transfer position, and that contacts the carrier when the transfer region passes through the transfer position ;
An image forming apparatus. In contact with the transfer member to rotate, an image forming apparatus according to 請 Motomeko 4 Ru comprising a removal member for removing foreign matter adhered to the transfer member.