JP5752089B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus including a charge eliminating unit that irradiates an image bearing member with light to neutralize the image bearing member.

  In an electrophotographic image forming apparatus, an intermediate transfer method is widely adopted. In the intermediate transfer method, an electrostatic latent image is formed on the surface of the photosensitive drum by charging the surface of the photosensitive drum, which is an image carrier, and exposing the surface of the charged photosensitive drum. The toner image is developed with toner to form a toner image, the toner image is primarily transferred to the intermediate transfer belt, and the toner image transferred to the intermediate transfer belt is secondarily transferred to a sheet to be transferred. It is a method.

  For example, when the intermediate transfer type image forming apparatus is a tandem type, the image forming apparatus includes an intermediate transfer belt. As the intermediate transfer belt, an annular belt that is stretched between a driving roller and a driven roller and rotates in a predetermined direction is used. The photosensitive drums (image carriers) of the respective colors (magenta (M), cyan (C), yellow (Y), and black (Bk)) are arranged at intervals in the rotation direction of the annular intermediate transfer belt. In addition, it is disposed opposite to the primary transfer roller with the intermediate transfer belt interposed therebetween. In this tandem type image forming apparatus, an electrostatic latent image is formed on the peripheral surface of each photosensitive drum by an exposure device, and the electrostatic latent image is developed by a developing device. The toner image is transferred onto the intermediate transfer belt in a multiple manner, and the toner image on the intermediate transfer belt is transferred to the conveyed paper to form (print) the image.

Here, the image forming apparatus described above includes a type having a color printing mode corresponding to color printing and a monochrome printing mode corresponding to monochrome printing.
Such an image forming apparatus is configured such that all the photosensitive drums corresponding to the respective colors are arranged in contact with the intermediate transfer belt in the color printing mode. Further, in the monochrome printing mode, the image forming apparatus is configured such that only the photosensitive drum corresponding to black (Bk) contacts the intermediate transfer belt, and the photosensitive drums corresponding to other colors are separated from the intermediate transfer belt. Is done.
That is, such an image forming apparatus is configured to change the positional relationship between the photosensitive drum (image forming unit) and the intermediate transfer belt in accordance with the print mode.
Further, such an image forming apparatus stops the rotation driving of the photosensitive drum corresponding to colors other than black (for example, magenta, cyan, yellow) in the monochrome printing mode.

In such an image forming apparatus, a transfer memory image and an exposure memory image may be generated on the surface of the photosensitive drum.
In the transfer memory image, a difference in transfer current flowing from the paper (transfer belt) to the photosensitive drum occurs between the printed portion and the non-printed portion at the time of transfer. This occurs because the surface potential difference is several to several tens V higher than the peripheral potential corresponding to the non-printed portion during recharging. When a transfer memory image is generated, the generated portion of the memory image is printed lighter than the peripheral density.

In addition, the exposure memory image is generated due to a surface potential difference that is lower by several V to several tens V than the peripheral potential in the exposed portion when the exposed portion is recharged. When the exposure memory image is generated, the generated portion of the memory image is printed darker than the peripheral density.
The surface potential difference generated between the transfer memory image and the exposure memory image varies depending on the specifications of the apparatus.

  In order to suppress the occurrence of the transfer memory image and the exposure memory image as described above, the area before the primary transfer and the area after the primary transfer on the photosensitive drum are each irradiated with a charge eliminating light, It is desirable to neutralize the surface.

  As an image forming apparatus having a charge eliminating unit that irradiates each of the area before the primary transfer and the area after the primary transfer in the photosensitive drum, the primary transfer position of the photosensitive drum, the photosensitive drum, and the like. A neutralizing light source that disposes a substrate between a cleaning unit that cleans residual toner remaining on the photosensitive drum and irradiates neutralizing light onto one surface of the photosensitive drum toward a region after the primary transfer on the photosensitive drum. At the same time, a part of the light emitted from the LED chip is transmitted to the other surface side of the substrate, and the primary transfer on the adjacent photosensitive drum is performed. There has been proposed an image forming apparatus including a charge removal portion having a configuration in which a through opening for irradiating charge removal light toward a previous region is formed (see, for example, Patent Document 1).

JP 2011-221405 A

However, in the image forming apparatus described in Patent Document 1, in the monochrome printing mode, the static elimination light is applied to the area before the primary transfer in the photosensitive drum corresponding to black (the adjacent photosensitive drum in the above). When irradiated, charge removal light is also applied to the photosensitive drum adjacent to the photosensitive drum corresponding to black.
In this case, the static elimination light is continuously applied to the photosensitive drum that is not used in the monochrome printing mode. As a result, the photosensitive drum may be deteriorated.

  An object of the present invention is to provide an image forming apparatus capable of irradiating an image carrier with static elimination light that suppresses generation of a transfer memory image and an exposure memory image while suppressing deterioration in the image carrier.

The image forming apparatus of the present invention is a plurality of image forming units arranged at intervals in the rotation direction of the intermediate transfer belt, and the image carrier and the intermediate position from the opposed position of the image carrier and the intermediate transfer belt. An image forming unit group including a plurality of image forming units each having a charge eliminating portion disposed on the downstream side in the rotation direction of the transfer belt is provided.
The image forming apparatus includes an image forming mode setting unit, a switching drive unit, a printing rate calculation unit, and a charge removal control unit.
The image forming mode setting unit is configured to be able to set an image forming mode.
When the first mode is set, the switching drive unit performs switching driving based on the mode set by the image forming mode setting unit. In the image forming unit group, the switching drive unit moves the first image forming unit disposed at a predetermined position excluding the most upstream side in the rotation direction of the intermediate transfer belt to a first transfer position that contacts the primary transfer position. A plurality of second image forming units different from the first image forming unit in the image forming unit group are arranged at a second non-transfer position spaced from the primary transfer position. The switching drive unit, when set to the second mode, places the first image forming unit at the first transfer position and abuts the plurality of second image forming units to the primary transfer position. It is arranged at the second transfer position.
The printing rate calculation unit calculates the printing rate in a state where the first mode is set by the image formation mode setting unit.
The charge removal control unit controls light irradiation in the plurality of charge removal units.
Among the plurality of second image forming units, in the adjacent second image forming unit arranged adjacent to the upstream side with respect to the first image forming unit in the rotation direction of the intermediate transfer belt, the adjacent second image The adjacent second static elimination unit constituting the forming unit emits the first light to the adjacent second image carrier constituting the adjacent second image forming unit, and the emitted first light is emitted from the adjacent second image carrier. A first image carrier that constitutes the first image forming unit and irradiates a downstream region in the rotation direction of the adjacent second image carrier with respect to a position facing the primary transfer position as a first charge eliminating light. The second light is emitted to the body side, and the emitted second light is directly or indirectly in the rotation direction of the first image carrier with respect to a position facing the primary transfer position on the first image carrier. Second in the upstream area Configured to illuminate as lightning.
The neutralization control unit integrally controls on / off of the irradiation of the first light and the second light in the adjacent second neutralization unit, and the printing rate calculated by the printing rate calculation unit is predetermined. When the printing rate is equal to or higher than the printing rate, the adjacent second static elimination unit is controlled to turn on the irradiation of the first light and the second light, and the printing rate calculated by the printing rate calculation unit is less than a predetermined printing rate. In some cases, the adjacent second static elimination unit is controlled to turn off the irradiation of the first light and the second light.

The image forming apparatus of the present invention is a plurality of image forming units arranged at intervals in the rotational direction of the intermediate transfer belt, and includes an image carrier, and a position where the image carrier and the intermediate transfer belt face each other. An image forming unit group including a plurality of image forming units each having a charge eliminating portion disposed on the downstream side in the rotation direction of the intermediate transfer belt.
The image forming apparatus includes an image forming mode setting unit, a switching drive unit, a detection unit, and a charge removal control unit.
The image forming mode setting unit is configured to be able to set an image forming mode.
The switching drive unit performs switching driving based on the mode set by the image forming mode setting unit. When the switching drive unit is set to the first mode, in the image forming unit group, the first image forming unit disposed at a predetermined position excluding the most upstream side in the rotation direction of the intermediate transfer belt is the first image forming unit. A first image carrier constituting an image forming unit is disposed at a first transfer position that abuts on a primary transfer position on the intermediate transfer belt, and a plurality of different image forming units from the first image forming unit in the image forming unit group. The second image forming unit is disposed at a second non-transfer position where the plurality of second image carriers constituting the plurality of second image forming units are separated from the primary transfer position. The switching drive unit, when set to the second mode, disposes the first image forming unit at the first transfer position and moves the plurality of second image forming units to the plurality of second image carriers. The body is disposed at a second transfer position where the body comes into contact with the primary transfer position.
The detection unit detects an image density and an image region of an image formed on the image carrier in a state where the first mode is set by the image formation mode setting unit.
The charge removal control unit controls light irradiation in the plurality of charge removal units.
Among the plurality of second image forming units, in the adjacent second image forming unit arranged adjacent to the upstream side with respect to the first image forming unit in the rotation direction of the intermediate transfer belt, the adjacent second image The adjacent second static elimination unit constituting the forming unit emits the first light to the adjacent second image carrier constituting the adjacent second image forming unit, and the emitted first light is emitted from the adjacent second image carrier. A first image carrier that constitutes the first image forming unit and irradiates a downstream region in the rotation direction of the adjacent second image carrier with respect to a position facing the primary transfer position as a first charge eliminating light. The second light is emitted to the body side, and the emitted second light is directly or indirectly in the rotation direction of the first image carrier with respect to a position facing the primary transfer position on the first image carrier. Second in the upstream area It configured to illuminate as lightning.
The static elimination control unit integrally controls on / off of the irradiation of the first light and the second light in the adjacent second static elimination unit, and the image density of the predetermined image is set to the first density by the detection unit. The image density of the next image formed continuously in the predetermined area in the same area as the image area formed on the image carrier is detected from the first density. Is detected to be lower than the second density, which is a lower density, the adjacent second static elimination unit is controlled to turn on the irradiation of the first light and the second light, and the detection unit controls the predetermined image. When the image density is detected to be equal to or higher than the first density and the image density in the next image is detected to be equal to or higher than the second density, the irradiation of the first light and the second light is turned off. Controlling the adjacent second static elimination unit to .

  According to the present invention, it is possible to provide an image forming apparatus that can irradiate an image carrier with static elimination light that suppresses generation of a transfer memory image and an exposure memory image while suppressing deterioration of the image carrier.

FIG. 3 is a diagram for explaining an arrangement of each component of the printer 1 according to the first embodiment. FIG. 2 is a longitudinal sectional view illustrating a configuration of an image forming unit GK in the printer 1 of the first embodiment. FIG. 4 is an enlarged cross-sectional view illustrating configurations of an image forming unit 15d that is a first image forming unit and an image forming unit 15c that is an adjacent second image forming unit in a color printing mode. FIG. 6 is an enlarged cross-sectional view illustrating configurations of an image forming unit 15d that is a first image forming unit and an image forming unit 15c that is an adjacent second image forming unit in a monochrome printing mode. 2 is a block diagram of the printer 1. FIG. FIG. 6 is a flowchart for explaining the operation of the printer 1. It is a block diagram in printer 1A of a 2nd embodiment. It is a longitudinal cross-sectional view explaining the other structure in an image formation part.

<First Embodiment>
Hereinafter, a first embodiment of an image forming apparatus will be described with reference to the drawings. The overall structure of the printer 1 as the first embodiment of the image forming apparatus will be described with reference to FIGS. 1 and 2. FIG. 1 is a diagram for explaining the arrangement of components of the printer 1 according to the first embodiment. FIG. 2 is a longitudinal sectional view illustrating the configuration of the image forming unit GK in the printer 1 of the first embodiment.

  As shown in FIG. 1, the printer 1 (image forming apparatus) forms an image of a predetermined toner image on a sheet T (sheet-like transfer material, sheet member) based on the apparatus main body M and predetermined image information. The image forming unit GK includes a forming unit GK and a paper supply / discharge unit KH that supplies the paper T to the image forming unit GK and discharges the paper T on which the toner image is formed. The outer shape of the apparatus main body M is configured by a case body BD as a casing. In the following description, the main scanning direction is X, the sub-scanning direction is Y, and the vertical direction of the printer 1 is Z.

  As shown in FIGS. 1 and 2, the image forming unit GK includes an annular intermediate transfer belt 7 using an endless belt that rotates in a rotation direction R1 (predetermined direction) indicated by an arrow in FIG. And a belt cleaning unit 20.

The image forming unit group 15 is a plurality of image forming units arranged at intervals in the rotation direction of the intermediate transfer belt 7, and the intermediate transfer belt in the rotation direction of the photosensitive drum (image carrier) and the photosensitive drum. 7 has a plurality of image forming units each having a charge eliminating portion disposed on the downstream side. In the present embodiment, the image forming unit group 15 includes a plurality of image forming units.
The image forming unit group 15 includes four image forming units 15a, 15b, 15c, and 15d.
The four image forming units are, in order from the upstream side, a yellow image forming unit 15a, a cyan image forming unit 15b, a magenta image forming unit 15c, and a black image forming unit 15d.

  The image forming unit group 15 includes a black image forming unit 15d as a first image forming unit and a plurality of second images which are image forming units of the four image forming units excluding the black image forming unit 15d. The image forming unit 15a for yellow, the image forming unit 15b for cyan, and the image forming unit 15c for magenta are provided as forming units.

  The black image forming unit 15d as the first image forming unit is disposed in a predetermined position in the image forming unit group 15 excluding the most upstream side in the rotation direction R1. In the present embodiment, the image forming unit 15d for black is disposed at the most downstream position in the rotation direction R in the image forming unit group 15.

In the present embodiment, among the plurality of second image forming units, the adjacent second arranged adjacent to the upstream side with respect to the black image forming unit 15d that is the first image forming unit in the rotation direction R1. The image forming unit is an image forming unit 15c for magenta.
The magenta image forming unit 15c, which is an adjacent second image forming unit, includes a photosensitive member, which will be described later, in which a charge eliminating unit 12c, which will be described later, included in the image forming unit 15c constitutes a black image forming unit 15d that is the first image forming unit. The body drum 2d is configured to irradiate a second charge removal light 142c (second light 132c) for charge removal before transfer.

The black image forming unit 15d as the first image forming unit is an image forming unit used in a color printing mode and a monochrome printing mode described later.
The black image forming unit 15d is disposed at a first transfer position that abuts a primary transfer position (described later) in the color printing mode and the monochrome printing mode.
Specifically, in the black image forming unit 15d, in the color printing mode and the monochrome printing mode, the photosensitive drum 2d (first image carrier) constituting the black image forming unit 15d is placed on the intermediate transfer belt 7. The first transfer position is in contact with the primary transfer position (described later).

The yellow image forming unit 15a, the cyan image forming unit 15b, and the magenta image forming unit 15c as a plurality of second image forming units are image forming units used in a color printing mode to be described later.
The image forming units 15a, 15b, and 15c are arranged at a second non-transfer position that is separated from a primary transfer position (described later) in the monochrome printing mode.
Specifically, in the monochrome printing mode, the image forming units 15a, 15b, and 15c are configured such that the photosensitive drums 2a, 2b, and 2c constituting the image forming units 15a, 15b, and 15c are the primary transfer on the intermediate transfer belt 7, respectively. It is arranged at a second non-transfer position that is separated from a position (described later).
The image forming units 15a, 15b, and 15c are arranged at a second transfer position that abuts on a primary transfer position (described later) in the color printing mode.
Specifically, in the color printing mode, the image forming units 15a, 15b, and 15c are configured such that the photosensitive drums 2a, 2b, and 2c constituting the image forming units 15a, 15b, and 15c are the primary transfer on the intermediate transfer belt 7, respectively. The second transfer position is in contact with a position (described later).

  The four image forming units 15a, 15b, 15c, and 15d constituting the image forming unit group 15 are arranged along the rotational direction R1 of the intermediate transfer belt 7 from the upstream side (left side in FIG. 1) to the downstream side (left side in FIG. 1). The intermediate transfer belt 7 is arranged in a line at a predetermined interval in the rotation direction R1 of the intermediate transfer belt 7 toward the right side in FIG.

  The belt cleaning unit 20 is disposed on the outer surface of the intermediate transfer belt 7 so as to face the upstream side of the four image forming units 15a, 15b, 15c, and 15d in the rotation direction R1 of the intermediate transfer belt 7. Residual toner remaining on the belt 7 is removed. The belt cleaning unit 20 includes a rotating brush 21 that rotates in contact with the intermediate transfer belt 7, a rotating roller 22 that removes the residual toner scraped off by the rotating brush 21, and a residual toner that stores the residual toner that has been wiped off. A storage case 23.

  The image forming units 15a, 15b, and 15c that are a plurality of second image forming units and the image forming unit 15d that is a first image forming unit are respectively photosensitive drums 2a, 2b, 2c, and 2d (first image carrier, first image carrier, 2 image carrier), charging units 10a, 10b, 10c, 10d, laser scanner units 4a, 4b, 4c, 4d, developing units 16a, 16b, 16c, 16d, and toner cartridges 5a, 5b, 5c, 5d. Toner supply units 6a, 6b, 6c, and 6d, cleaning units 11a, 11b, 11c, and 11d, and charge eliminating units 12a, 12b, 12c, and 12d.

  As shown in FIG. 1, the paper feed / discharge unit KH includes a paper feed cassette 52, a manual paper feed unit 64, a paper T conveyance path L, a registration roller pair 80, a plurality of rollers or roller pairs, and a paper discharge unit. A paper unit 50. As will be described later, the transport path L is an aggregate of a first transport path L1, a second transport path L2, a third transport path L3, a manual transport path La, and a return transport path Lb.

Hereinafter, each configuration of the four image forming units 15a, 15b, 15c, and 15d of the image forming unit GK and the paper supply / discharge unit KH will be described in detail. First, the image forming units 15a, 15b, 15c, and 15d of the image forming unit GK will be described.
In each of the image forming units 15a, 15b, 15c, and 15d, charging by the charging units 10a, 10b, 10c, and 10d is performed in order from the upstream side to the downstream side along the surface of each of the photosensitive drums 2a, 2b, 2c, and 2d. Exposure by laser scanner units 4a, 4b, 4c, 4d, development by developing units 16a, 16b, 16c, 16d, primary transfer by intermediate transfer belt 7 and primary transfer rollers 37a, 37b, 37c, 37d, static elimination unit 12a, The neutralization by 12b, 12c, and 12d and the cleaning by the cleaning units 11a, 11b, 11c, and 11d are performed. Further, secondary transfer by the intermediate transfer belt 7, the secondary transfer roller 8 and the counter roller 18, and fixing by the fixing unit 9 are performed.

  Each of the photosensitive drums 2a, 2b, 2c, and 2d is formed of a cylindrical member and functions as a photosensitive member or an image carrier. Each of the photosensitive drums 2 a, 2 b, 2 c, and 2 d is disposed to face a primary transfer position (described later) on the outer surface side of the intermediate transfer belt 7 and extends in a direction orthogonal to the traveling direction of the intermediate transfer belt 7. It is arranged so as to be rotatable in the direction of the arrow around the axis. An electrostatic latent image can be formed on the surface of each of the photosensitive drums 2a, 2b, 2c, and 2d.

  Each of the photosensitive drums 2a, 2b, 2c, and 2d is rotationally driven by a rotational driving unit 130 described later. Specifically, each of the photosensitive drums 2 a, 2 b, 2 c, and 2 d is driven to rotate at a predetermined rotation speed for a predetermined time by the rotation driving unit 130 controlled by the rotation driving control unit 250.

  Each of the charging units 10a, 10b, 10c, and 10d is disposed to face the surface of each of the photosensitive drums 2a, 2b, 2c, and 2d. Each of the charging units 10a, 10b, 10c, and 10d uniformly charges the surface of each of the photosensitive drums 2a, 2b, 2c, and 2d negatively (minus polarity) or positively (plus polarity).

  The laser scanner units 4a, 4b, 4c, and 4d function as exposure units, and are spaced apart from the surfaces of the photosensitive drums 2a, 2b, 2c, and 2d. Each of the laser scanner units 4a, 4b, 4c, and 4d includes a laser light source (not shown), a polygon mirror, a polygon mirror driving motor, and the like.

  Each of the laser scanner units 4a, 4b, 4c, and 4d scans and exposes the surface of each of the photosensitive drums 2a, 2b, 2c, and 2d based on image information input from an external device such as a PC (personal computer). The scanning exposure is performed by each of the laser scanner units 4a, 4b, 4c, and 4d, thereby removing the charges on the exposed portions of the surfaces of the photosensitive drums 2a, 2b, 2c, and 2d. Thereby, electrostatic latent images are formed on the respective surfaces of the photosensitive drums 2a, 2b, 2c, and 2d.

The developing units 16a, 16b, 16c, and 16d are provided corresponding to the photosensitive drums 2a, 2b, 2c, and 2d, respectively, and are disposed to face the surfaces of the photosensitive drums 2a, 2b, 2c, and 2d. Each of the developing units 16a, 16b, 16c, and 16d attaches toner of each color to the electrostatic latent image formed on the surface of each of the photosensitive drums 2a, 2b, 2c, and 2d, and converts the color toner image into the photosensitive drum. 2a, 2b, 2c and 2d are formed on the respective surfaces. Each of the developing units 16a, 16b, 16c, and 16d corresponds to four colors of yellow, cyan, magenta, and black. Each of the developing units 16a, 16b, 16c, and 16d includes a developing roller disposed on the surface of the photosensitive drums 2a, 2b, 2c, and 2d, a stirring roller for stirring the toner, and the like.
Each of the developing units 16b, 16c, and 16d is arranged in a predetermined positional relationship with each of the static eliminating units 12a, 12b, and 12c. This positional relationship will be described later.

  Each of the toner cartridges 5a, 5b, 5c, and 5d is provided corresponding to each of the developing units 16a, 16b, 16c, and 16d, and each color toner supplied to each of the developing units 16a, 16b, 16c, and 16d. To accommodate. Each of the toner cartridges 5a, 5b, 5c, and 5d accommodates yellow toner, cyan toner, magenta toner, and black toner.

  The toner supply units 6a, 6b, 6c, and 6d are provided corresponding to the toner cartridges 5a, 5b, 5c, and 5d and the developing units 16a, 16b, 16c, and 16d, respectively. The toners of the respective colors accommodated in 5d are supplied to the developing units 16a, 16b, 16c, and 16d, respectively. Each of the toner supply units 6a, 6b, 6c, and 6d and each of the developing units 16a, 16b, 16c, and 16d are connected by a toner supply path (not shown).

To the intermediate transfer belt 7, the toner images of the respective colors formed on the photosensitive drums 2a, 2b, 2c, and 2d are sequentially primary-transferred. The intermediate transfer belt 7 is stretched around a driven roller 35, a counter roller 18 including a driving roller, a tension roller 36 (not shown in FIG. 2), and the like. Since the tension roller 36 biases the intermediate transfer belt 7 from the inside to the outside, a predetermined tension is applied to the intermediate transfer belt 7.
In the present embodiment, the intermediate transfer belt 7 is used as a light reflecting portion that reflects second light (second charge eliminating light) described later.

  Primary transfer rollers 37a, 37b, 37c, and 37d are arranged to face each other on the side opposite to the photosensitive drums 2a, 2b, 2c, and 2d with the intermediate transfer belt 7 interposed therebetween.

  The intermediate transfer belt 7 is sandwiched between the primary transfer rollers 37a, 37b, 37c, and 37d and the photosensitive drums 2a, 2b, 2c, and 2d, respectively, at predetermined positions. The predetermined portion thus sandwiched is pressed against the surface of each of the photosensitive drums 2a, 2b, 2c, and 2d. Primary transfer nips N1a, N1b, N1c, and N1d are formed between the photosensitive drums 2a, 2b, 2c, and 2d and the primary transfer rollers 37a, 37b, 37c, and 37d, respectively. In each of the primary transfer nips N1a, N1b, N1c, and N1d, the toner images of the respective colors developed on the photosensitive drums 2a, 2b, 2c, and 2d are sequentially primary-transferred onto the intermediate transfer belt 7, respectively. As a result, a full-color toner image is formed on the intermediate transfer belt 7.

  To the primary transfer rollers 37a, 37b, 37c, and 37d, toner images of the respective colors formed on the photosensitive drums 2a, 2b, 2c, and 2d are respectively transferred to the intermediate transfer belt 7 by a primary transfer bias applying unit (not shown). A primary transfer bias for transferring the toner image is applied.

The neutralization units 12a, 12b, 12c, and 12d are disposed to face the surfaces of the photosensitive drums 2a, 2b, 2c, and 2d, respectively. Each of the charge removal units 12a, 12b, 12c, and 12d irradiates light (first charge removal light) on the surface of each of the photoreceptor drums 2a, 2b, 2c, and 2d, and then the photoreceptor after the primary transfer. The surface of each of the drums 2a, 2b, 2c, and 2d is discharged (removal of charges, charge removal after transfer). In addition, each of the charge removal units 12a, 12b, and 12c irradiates light (second charge removal light) on the surface of each of the photosensitive drums 2b, 2c, and 2d, and thereby the photosensitive drum 2b before the primary transfer is performed. The surface of each of 2c and 2d is discharged (removal of charge, charge removal before transfer).
In the present embodiment, each of the charge removal units 12a, 12b, and 12c is configured to integrally emit the first light (first charge removal light) and the second light (second charge removal light). Each of the static elimination units 12a, 12b, and 12c integrally turns on / off light emission (irradiation) of the first light (first static elimination light) and the second light (second static elimination light) by the static elimination control unit 230 described later. Controlled to switch.
The charge removal units 12a, 12b, 12c, and 12d will be described later.

  Each of the cleaning portions 11a, 11b, 11c, and 11d is disposed to face the surface of each of the photosensitive drums 2a, 2b, 2c, and 2d. Each of the cleaning units 11a, 11b, 11c, and 11d removes toner and adhering matter remaining on the surfaces of the photosensitive drums 2a, 2b, 2c, and 2d, and conveys the removed toner and the like to a predetermined recovery mechanism. And collect.

  The secondary transfer roller 8 secondarily transfers the full-color toner image primarily transferred to the intermediate transfer belt 7 onto the paper T. A secondary transfer bias for transferring a full color toner image formed on the intermediate transfer belt 7 to the paper T is applied to the secondary transfer roller 8 by a secondary transfer bias applying unit (not shown).

  The secondary transfer roller 8 contacts or separates from the intermediate transfer belt 7. Specifically, the secondary transfer roller 8 is configured to be movable between a contact position where the secondary transfer roller 8 is in contact with the intermediate transfer belt 7 and a separation position where the secondary transfer roller 8 is separated from the intermediate transfer belt 7. Specifically, the secondary transfer roller 8 is disposed at a contact position when the full-color toner image primarily transferred onto the surface of the intermediate transfer belt 7 is secondarily transferred to the paper T, and in other cases. It is arranged at a separated position.

  A counter roller 18 is disposed on the opposite side of the intermediate transfer belt 7 from the secondary transfer roller 8. The intermediate transfer belt 7 is sandwiched between the secondary transfer roller 8 and the opposing roller 18 at a predetermined position. Then, the paper T is pressed against the outer surface of the intermediate transfer belt 7 (the surface on which the toner image is primarily transferred). A secondary transfer nip N <b> 2 is formed between the intermediate transfer belt 7 and the secondary transfer roller 8. In the secondary transfer nip N2, the full-color toner image primarily transferred to the intermediate transfer belt 7 is secondarily transferred to the paper T.

  The fixing unit 9 melts and presses the toner of each color constituting the toner image secondarily transferred onto the paper T and fixes the toner on the paper T. The fixing unit 9 includes a heating rotator 9a heated by a heater and a pressure rotator 9b pressed against the heating rotator 9a. The heating rotator 9a and the pressure rotator 9b sandwich and pressurize the paper T onto which the toner image has been secondarily transferred, and convey the paper T. When the paper T is conveyed while being sandwiched between the heating rotator 9a and the pressure rotator 9b, the toner transferred to the paper T is fixed on the paper T by being melted and pressurized. Is done.

Next, the paper supply / discharge unit KH will be described.
As shown in FIG. 1, a sheet feeding cassette 52 serving as a main accommodating portion that accommodates the paper T is disposed below the apparatus main body M. The paper feed cassette 52 is configured to be pulled out from the housing of the apparatus main body M in the horizontal direction. In the paper feed cassette 52, a placement plate 60 on which the paper T is placed is disposed. In the paper feed cassette 52, the paper T is stored in a state of being stacked on the placement plate 60. The paper T placed on the placement plate 60 is sent out to the transport path L by the paper feed unit 51 disposed at the paper feed side end of the paper feed cassette 52 (the right end in FIG. 1). The paper feed unit 51 includes a double feed prevention mechanism including a forward feed roller 61 for taking out the paper T on the placement plate 60 and a paper feed roller pair 81 for feeding the paper T to the transport path L one by one. Prepare.

  On the left side surface (left side in FIG. 1) of the apparatus main body M, a manual paper feed unit 64 that accommodates the paper T is provided. The manual paper feed unit 64 is provided mainly for supplying the apparatus main body M with a paper T of a size and type different from the paper T set in the paper feed cassette 52. The manual paper feed unit 64 includes a manual feed tray 65 that forms a part of the left side surface of the apparatus main body M in the closed state, and a paper feed roller 66. The manual feed tray 65 is attached to the vicinity of the paper feed roller 66 at its lower end so as to be rotatable (openable and closable). The paper T is placed on the open manual feed tray 65. The paper feed roller 66 feeds the paper T placed on the open manual feed tray 65 to the manual feed path La.

  The conveyance path L for conveying the paper T includes a first conveyance path L1 from the paper feeding unit 51 to the secondary transfer nip N2, a second conveyance path L2 from the secondary transfer nip N2 to the fixing unit 9, and a fixing unit 9. From the downstream side to the upstream side, and the third conveyance path L3 from the downstream side to the upstream side, the manual conveyance path La that joins the paper supplied from the paper supply unit 64 to the first conveyance path L1, and the third conveyance path L3. A return conveyance path Lb that reverses the sheet to be conveyed and returns it to the first conveyance path L1.

  The first transport path L1 transports the paper T stored in the paper feed cassette 52 toward the image forming unit GK. The manual feed path La transports the paper T accommodated in the manual paper feed unit 64 toward a registration roller pair 80 described later.

  Moreover, the 1st junction part P1 and the 2nd junction part P2 are provided in the middle of the 1st conveyance path L1. A first branch portion Q1 is provided in the middle of the third transport path L3. The first joining part P1 is a joining part where the manual feed path La joins the first transport path L1. The second junction P2 is a junction where the return conveyance path Lb merges with the first conveyance path L1. The first branch portion Q1 is a branch portion where the return transport path Lb branches from the third transport path L3.

  In the middle of the first conveyance path L1 (specifically, between the second joining portion P2 and the secondary transfer roller 8), a paper detection sensor (not shown) for detecting the paper T, A registration roller pair 80 is arranged to synchronize with skew (oblique feeding) correction and toner image formation in the image forming unit GK. The paper detection sensor is disposed immediately before the registration roller pair 80 in the transport direction of the paper T (upstream in the transport direction). The registration roller pair 80 conveys the paper T by performing the above correction and timing adjustment based on the detection signal information from the paper detection sensor.

  Between the 1st confluence | merging part P1 and the 2nd confluence | merging part P2 in the 1st conveyance path L1, the 1st conveyance roller pair 82 as a 1st roller is arrange | positioned. The first transport roller pair 82 is disposed on the downstream side of the paper feed roller pair 81, sandwiches the paper T transported by the paper feed roller pair 81, and transports the paper T to the registration roller pair 80 as the second roller.

  The return conveyance path Lb is a conveyance path that is provided to make the opposite surface (unprinted surface) opposite to the already printed surface to the intermediate transfer belt 7 when performing duplex printing on the paper T. In the return conveyance path Lb, a plurality of second conveyance roller pairs 83 that convey the paper T toward the second joining portion P2 are arranged at predetermined intervals. According to the return transport path Lb, the paper T transported from the first branching section Q1 to the paper discharge section 50 is turned upside down and returned to the first transport path L1, and is disposed upstream of the secondary transfer roller 8. It can be conveyed upstream of the registration roller pair 80. A predetermined toner image is transferred at the secondary transfer nip N2 to the unprinted surface of the paper T that is reversed upside down by the return conveyance path Lb.

  A rectifying member 58 is provided in the first branch portion Q1. The rectifying member 58 rectifies the transport direction of the paper T that is carried out of the fixing unit 9 and transports the third transport path L3 from the upstream side toward the downstream side in a direction toward the paper discharge unit 50 and the paper discharge unit 50. The conveyance direction of the paper T that conveys the third conveyance path L3 from the downstream side toward the upstream side is rectified in the direction toward the return conveyance path Lb.

  A paper discharge unit 50 is formed at the end of the third transport path L3. The paper discharge unit 50 is disposed on the upper side of the apparatus main body M. The paper discharge unit 50 opens toward the left side of the apparatus body M (left side in FIG. 1). The paper discharge unit 50 discharges the paper T to the outside of the apparatus main body M. The paper discharge unit 50 includes a discharge roller pair 53. According to the discharge roller pair 53, the paper T transported from the upstream side to the downstream side in the third transport path L3 is discharged to the outside of the apparatus main body M, and the transport direction of the paper T is reversed in the paper discharge unit 50. Thus, the paper T can be transported toward the upstream side of the third transport path L3.

  On the opening side of the paper discharge unit 50, a paper discharge stacking unit M1 is formed. The paper discharge stacking unit M1 is formed on the upper surface (outer surface) of the apparatus main body M. The paper discharge stacking unit M1 is a part formed by the upper surface of the apparatus main body M being depressed downward. The bottom surface of the paper discharge stacking unit M1 is formed by a top cover member M2 as an opening / closing member that constitutes a part of the top surface of the apparatus main body M. A sheet T on which a predetermined toner image is formed and discharged from the paper discharge unit 50 is stacked and integrated on the upper surface of the top cover member M2 forming the paper discharge stacking unit M1. A sheet detection sensor is disposed at a predetermined position in each conveyance path.

Next, the operation of the printer 1 of the first embodiment will be briefly described with reference to FIG. First, a case where single-sided printing is performed on the paper T stored in the paper feed cassette 52 will be described.
The paper T accommodated in the paper feed cassette 52 is sent out to the first transport path L1 by the forward feed roller 61 and the paper feed roller pair 81, and then the first transport path L1 and the first transport path L1 through the first transport path L1. The sheet is conveyed to the registration roller pair 80 by the one conveyance roller pair 82. In the registration roller pair 80, skew correction of the paper T and timing adjustment with toner image formation in the image forming unit GK are performed.

  The paper T discharged from the registration roller pair 80 is introduced between the intermediate transfer belt 7 and the secondary transfer roller 8 (secondary transfer nip N2) via the first conveyance path L1. Then, a toner image is transferred onto the paper T between the intermediate transfer belt 7 and the secondary transfer roller 8. Thereafter, the paper T is discharged from between the intermediate transfer belt 7 and the secondary transfer roller 8, and is interposed between the heating rotator 9a and the pressure rotator 9b in the fixing unit 9 via the second conveyance path L2. Introduced into the fixing nip. Then, the toner melts in the fixing nip, and the toner is fixed on the paper T.

  Next, the paper T is transported to the paper discharge unit 50 through the third transport path L3, and is discharged from the paper discharge unit 50 to the paper discharge stacking unit M1 by the discharge roller pair 53. In this way, single-sided printing of the paper T stored in the paper feed cassette 52 is completed.

  When single-sided printing is performed on the paper T placed on the manual feed tray 65, the paper T placed on the manual feed tray 65 is sent out to the manual feed path La by the paper feed roller 66, and then the first joining portion. It is conveyed to the registration roller pair 80 via P1 and the first conveyance path L1. Subsequent operations are the same as the one-side printing operation of the paper T accommodated in the paper feed cassette 52 described above, and a description thereof will be omitted.

Next, the operation of the printer 1 when performing duplex printing will be described.
In the case of single-sided printing, as described above, the paper T on which single-sided printing has been performed is discharged from the paper discharge unit 50 to the paper discharge stacking unit M1, and the printing operation is completed. On the other hand, when performing double-sided printing, the paper T on which single-sided printing has been performed is reversed from the time of single-sided printing and conveyed again to the registration roller pair 80 via the return conveyance path Lb. Then, double-sided printing is performed on the paper T.

  More specifically, the operation is the same as the above-described single-sided printing operation until the paper T on which single-sided printing has been performed is discharged from the paper discharge unit 50 by the discharge roller pair 53. Thus, in the case of double-sided printing, in a state where the paper T on which single-sided printing has been performed is held by the discharge roller pair 53, the rotation of the discharge roller pair 53 is stopped and rotated in the reverse direction. When the discharge roller pair 53 is thus rotated in the reverse direction, the paper T held by the discharge roller pair 53 moves in the reverse direction (the direction from the paper discharge unit 50 toward the first branching unit Q1) along the third conveyance path L3. ).

  As described above, when the paper T is transported in the reverse direction on the third transport path L3, the paper T is rectified to the return transport path Lb by the rectifying member 58, and then, via the second junction P2. Then, it joins the first transport path L1. Here, the paper T is turned upside down from the one-side printing.

  Further, the paper T is corrected or adjusted by the registration roller pair 80, and is introduced into the secondary transfer nip N2 through the first conveyance path L1. Since the unprinted surface of the sheet T passes through the return conveyance path Lb and faces the intermediate transfer belt 7, the toner image is transferred to the unprinted surface, and as a result, duplex printing is performed.

  Next, with reference to FIGS. 3A and 3B, the configuration of the charge removal units 12a, 12b, 12c, and 12d in the four image forming units 15a, 15b, 15c, and 15d of the printer 1 of the first embodiment will be described. FIG. 3A is an enlarged cross-sectional view illustrating configurations of an image forming unit 15d that is a first image forming unit and an image forming unit 15c that is an adjacent second image forming unit in the color printing mode. FIG. 3B is an enlarged cross-sectional view illustrating configurations of an image forming unit 15d that is a first image forming unit and an image forming unit 15c that is an adjacent second image forming unit in the monochrome printing mode.

As shown in FIGS. 2 and 3A, in the image forming units 15a, 15b, 15c, and 15d constituting the image forming unit group 15, each of the static eliminating units 12a, 12b, 12c, and 12d has a primary transfer position and a cleaning. It arrange | positions between the parts 11a, 11b, 11c, and 11d.
The primary transfer position is a position where primary transfer nips N1a, N1b, N1c, and N1d are formed in the rotation directions of the photosensitive drums 2a, 2b, 2c, and 2d.

In the present embodiment, the neutralization units 12a, 12b, and 12c that constitute the image forming units 15a, 15b, and 15c have intermediate distances from the intermediate transfer belt 7 to the neutralization units 12a, 12b, and 12c (each neutralization light source), respectively. More than the distance from the transfer belt 7 to the upper edge of each of the developing units 16b, 16c, 16d constituting the image forming units 15b, 15c, 15d arranged adjacent to the downstream side in the rotation direction R1 of the intermediate transfer belt 7. It is arranged at a long position.
In other words, the neutralization unit constituting any one of the image forming units 15a, 15b, and 15c has a distance from the intermediate transfer belt 7 to the downstream side in the rotation direction R1 of the intermediate transfer belt 7 from the intermediate transfer belt 7. Is disposed at a position that is longer than the distance to the developing unit constituting the image forming unit disposed adjacent to the image forming unit.

The neutralization units 12a, 12b, 12c, and 12d are respectively provided with the first light 131a, 131b, and the first light 131a, 131b, and the photoconductive drums 2a, 2b, 2c, and 2d constituting the image forming units 15a, 15b, 15c, and 15d including the respective neutralization units. Light exits 131c and 131d.
The emitted first light 131a, 131b, 131c, 131d is a downstream area in the rotation direction of each photosensitive drum with respect to the position facing the primary transfer position in each of the photosensitive drums 2a, 2b, 2c, 2d. Each is irradiated as the first static elimination light 141a, 141b, 141c, 141d.
Specifically, the emitted first lights 131a, 131b, 131c, and 131d are cleaned from the positions facing the primary transfer positions of the photosensitive drums 2a, 2b, 2c, and 2d, respectively, from the cleaning units 11a, 11b, 11c, and 11d. Are irradiated as first static elimination light beams 141a, 141b, 141c, and 141d. As a result, each of the static elimination units 12a, 12b, 12c, and 12d is subjected to post-transfer static elimination with respect to the photosensitive drums 2a, 2b, 2c, and 2d constituting the image forming units 15a, 15b, 15c, and 15d including the respective static elimination units. I do.

Further, each of the neutralization units 12a, 12b, and 12c is provided with three image forming units arranged on the downstream side in the rotation direction R1 of the intermediate transfer belt 7 and adjacent to the image forming units 15a, 15b, and 15c including the respective neutralization units. Second light 132a, 132b, 132c is emitted to the photosensitive drums 2b, 2c, 2d constituting the units 15b, 15c, 15d.
In the present embodiment, each of the static elimination units 12a, 12b, and 12c reflects the emitted second light 132a, 132b, and 132c to the intermediate transfer belt 7, and the intermediate transfer belt 7 and the adjacent image forming units 15b and 15c. , 15d, the spaces between the developing sections 16b, 16c and 16d are passed.
Then, each of the static eliminating units 12a, 12b, and 12c reflects the second reflected light to the upstream region in the rotation direction of each photosensitive drum with respect to the position facing the primary transfer position in the photosensitive drums 2b, 2c, and 2d. Lights 132a, 132b, and 132c are emitted as second static elimination lights 142a, 142b, and 142c.
Specifically, each of the static eliminating units 12a, 12b, and 12c is located in a region between a position facing the developing units 16b, 16c, and 16d on the photosensitive drums 2b, 2c, and 2d and a position facing the primary transfer position. The reflected second light 132a, 132b, 132c is irradiated as the second static elimination light 142a, 142b, 142c.
As a result, each of the static elimination units 12a, 12b, and 12c is provided with the photosensitive drums 2b, 2c, and 2d constituting the image forming units 15b, 15c, and 15d adjacent to the image forming units 15a, 15b, and 15c including the static elimination units, respectively. Perform static elimination before transfer.
Further, here, the neutralization unit 12c (adjacent second neutralization unit) is downstream in the rotation direction of the photosensitive drum 2c with respect to the position facing the primary transfer position in the photosensitive drum 2c (adjacent second image carrier). The first light 131c (first charge removal light 141c) is emitted to the side, and upstream in the rotational direction of the photosensitive drum 2d with respect to the position facing the primary transfer position on the photosensitive drum 2d (first image carrier). The second light 132c (second charge removal light 142c) is emitted to the side.

As described above, the static eliminators 12a, 12b, and 12c constituting the image forming units 15a, 15b, and 15c, which are the second image forming units, respectively, include the image forming units 15a, 15b, and 15c including the static eliminators 12a, 12b, and 12c. The first light is emitted to the constituent photosensitive drums 2a, 2b, and 2c, and the region between the position facing the primary transfer position and the position facing the cleaning unit on the photosensitive drums 2a, 2b, and 2c. Irradiate the first charge eliminating light.
Each of the static elimination units 12a, 12b, and 12c emits the second light to the photosensitive drums 2b, 2c, and 2d constituting the image forming units 15b, 15c, and 15d disposed adjacent to the downstream side in the rotation direction R. Idemitsu. The emitted second light is reflected by the intermediate transfer belt, passes through a space between the intermediate transfer belt and the developing unit constituting the adjacent image forming unit, and from a position facing the developing unit on the photosensitive drum. The region between the position opposite to the primary transfer position is irradiated as the second charge removal light.

Of the image forming units 15a, 15b, 15c, and 15d that constitute the image forming unit group, the neutralization unit 12d that constitutes the image forming unit 15d that is disposed on the most downstream side in the rotation direction R1 of the intermediate transfer belt 7 includes Two lights are not emitted.
Of the four image forming units 15a, 15b, 15c, and 15d, the photosensitive drum 2a that constitutes the image forming unit 15a that is disposed on the most upstream side in the rotation direction R1 of the intermediate transfer belt 7 has a second charge eliminating light. Is not irradiated.

  The neutralization units 12a, 12b, and 12c are arranged at predetermined intervals along the main scanning direction X, and the plurality of first LEDs that emit the first lights 131a, 131b, and 131c and at predetermined intervals along the main scanning direction X. And a plurality of second LEDs that emit the second light 132a, 132b, and 132c. The neutralization unit 12d includes a plurality of first LEDs that are arranged at predetermined intervals along the main scanning direction X and emit the first light 131d.

Each of the static elimination units 12a, 12b, and 12c can reduce power consumption by using an LED as a light source element that emits the first light 131a, 131b, and 131c and the second light 132a, 132b, and 132c. The light amounts of the first light 131a, 131b, 131c and the second light 132a, 132b, 132c can be adjusted appropriately.
The neutralization unit (printer 1) suppresses variations in light intensity in the main scanning direction X for each of the first neutralization light and the second neutralization light, and performs neutralization with little variation in the main scanning direction X. The intensity of each of the first static elimination light and the second static elimination light can be adjusted appropriately.

  Each of the charge removal units 12a, 12b, 12c, and 12d includes, for example, a substrate on which an LED is mounted. Each of the static eliminating units 12a, 12b, and 12c includes a substrate on which a plurality of first LEDs and a plurality of second LEDs are mounted. Each of the substrates has, for example, an elongated shape that is long in the main scanning direction X.

The light amounts of the first charge removal lights 141a, 141b, and 141c are set larger than the light amounts of the second charge removal lights 142a, 142b, and 142c, respectively.
The first static elimination light 141a, 141b, 141c that performs static elimination after transfer generates a transfer memory image and an exposure memory image that are generated when a surface potential difference of several tens to several tens of volts occurs between the printed portion and the non-printed portion. A sufficient amount of light is required to suppress the above.
On the other hand, when the light intensity of the second charge removal lights 142a, 142b, and 142c that perform charge removal before transfer is excessive, a problem occurs in that toner of the downstream color scatters from the photosensitive drum during multiple transfer.
In consideration of the balance between the post-transfer charge removal and the pre-transfer charge removal, the light quantity of the first charge removal light and the second charge removal light on each irradiated surface are the light quantities of the first charge removal lights 141a, 141b, and 141c> the first charge removal light. 2 It sets so that it may become the light quantity of the static elimination light 142a, 142b, 142c.

Moreover, the emitted light quantity in each 2nd LED is set larger than the emitted light quantity in each 1st LED.
Each of the first static elimination lights 141a, 141b, and 141c that perform static elimination after transfer has a relatively short optical path length, and has little light diffusion and light attenuation.
On the other hand, each of the second static elimination lights 142a, 142b, and 142c that perform static elimination before transfer has a relatively long optical path length and a large amount of light diffusion and attenuation.
In consideration of the above, the emitted light amount of the first LED and the emitted light amount of the second LED are set so that the emitted light amount of the second LED> the emitted light amount of the first LED.
As a result, the intensity (light quantity) of the first charge elimination light 141a, 141b, 141c and the second charge elimination light 142a, 142b, 142c is multiplexed while suppressing the generation of the transfer memory image and the exposure memory image as described above. The strength (light quantity) is set so as to obtain a suitable state in which the occurrence of a problem such that the downstream color toner scatters from the photosensitive drum during transfer is suppressed.

Among the image forming units 15a, 15b, 15c, and 15d constituting the image forming unit group 15, the photosensitive drum 2a constituting the image forming unit 15a disposed on the most upstream side in the rotation direction R1 of the intermediate transfer belt 7 includes The second charge eliminating light is not irradiated.
Here, on the outer surface of the intermediate transfer belt 7, the position facing the most upstream side of the image forming unit group 15 (image forming units 15 a, 15 b, 15 c, 15 d) in the rotation direction R 1 of the intermediate transfer belt 7 is A belt cleaning unit 20 for removing residual toner remaining on the intermediate transfer belt 7 is disposed. For this reason, even if the pre-transfer charge removal by the second charge removal light is not performed, the trouble that the downstream color toner scatters from the photosensitive drum 2a at the time of multiple transfer does not occur.
For this reason, the printer 1 according to the present embodiment employs a configuration in which the second charge eliminating light is not applied to the photosensitive drum 2a constituting the image forming unit 15a.

Here, as illustrated in FIGS. 3A and 3B, the printer 1 is configured to be able to set a mode for a color printing mode and a monochrome printing mode.
The color printing mode is a mode in which the printer 1 can form a color image on the paper T (image forming material, sheet member).
The monochrome printing mode is a mode in which the printer 1 can print only a monochrome image on the paper T.

The printer 1 includes a switching drive unit 120 that performs switching driving based on the set image mode.
As shown in FIGS. 3A and 3B, the switching drive unit 120 transfers the plurality of second image forming units 15a, 15b, and 15c to the second transfer position based on the set image mode. Arranged at the second non-transfer position.

  Specifically, when the image forming mode is set to the monochrome printing mode (first mode), the switching drive unit 120 moves the image forming unit 15d (for black, first image forming unit) to the black image. The photosensitive drum 2d (first image carrier) constituting the forming unit 15d is disposed at the first transfer position where the photosensitive drum 2d (first image carrier) contacts the primary transfer position on the intermediate transfer belt 7, and the image forming units 15a, 15b, 15c (yellow, Cyan, magenta, and a plurality of second image forming units) are separated from the primary transfer position by the photosensitive drums 2a, 2b, and 2c (a plurality of second image carriers) constituting the image forming units 15a, 15b, and 15c. It arrange | positions at a 2nd non-transfer position.

  Further, when the image forming mode is set to the color printing mode (second mode), the switching drive unit 120 replaces the image forming unit 15d (for black, the first image forming unit) with the image forming unit 15d for black. And the image forming units 15a, 15b, and 15c (yellow, cyan, magenta) and the photosensitive drum 2d (first image carrier) constituting the image forming unit 15 are disposed at the first transfer position that contacts the primary transfer position on the intermediate transfer belt 7. , A plurality of second image forming units), and second photosensitive drums 2a, 2b, 2c (a plurality of second image carriers) constituting the image forming units 15a, 15b, 15c are in contact with the primary transfer position. Place at the transfer position.

Next, a functional configuration of the printer 1 will be described with reference to FIG. FIG. 4 is a block diagram of the printer 1.
As illustrated in FIG. 4, the printer 1 includes an interface unit 100, an operation input unit 110, a switching drive unit 120, a rotation drive unit 130, a charge removal unit 12 c, a control unit 200, and a storage unit 300. Have.

The interface unit 100 is configured to accept information from the outside. The interface unit 100 is connected to, for example, a terminal device (for example, a personal computer (PC)) via a communication network.
For example, the interface unit 100 receives job information including image information from a terminal device.
For example, the interface unit 100 stores job information including image information received from the terminal device in the job information storage unit 310 described later.

The operation input unit 110 is configured to accept a user operation input to the printer 1. The operation input unit 110 is configured to accept an operation input for selecting an image forming mode from a user, for example.
The operation input unit 110 includes, for example, a plurality of hard keys, a touch panel, and the like.

The touch panel is configured to accept an operation input from a user. The touch panel includes a display unit and a touch sensor unit.
The display unit is configured to display soft keys including icons, buttons, and the like.
The touch sensor unit is disposed on the display surface side of the display unit. The touch sensor unit can employ any method including an analog resistance film method and a capacitance method. The touch sensor unit detects gesture information including a contact position and / or a contact area on a contact object (for example, a user's finger, touch pen), and outputs the detected gesture information to a predetermined function unit including the control unit 200. Configured to be possible.

  As described above, the switching drive unit 120 converts the image forming units 15a, 15b, and 15c, which are a plurality of second image forming units, to the second based on the image forming mode set by the image forming mode setting unit 210 described later. They are arranged at the transfer position and the second non-transfer position.

  The rotation driving unit 130 drives each of the photosensitive drums 2a, 2b, 2c, and 2d to rotate. The rotation driving unit 130 is configured to be able to individually drive / stop rotation of the photosensitive drums 2a, 2b, 2c, and 2d. The rotation driving unit 130 is configured to be able to rotate the photosensitive drums 2a, 2b, 2c, and 2d at different rotational speeds.

As described above, the charge removal unit 12c is a charge removal unit that configures the image forming unit 15c that is the adjacent second image forming unit that is disposed adjacent to the upstream side of the image forming unit 15d that is the first image forming unit. is there.
The neutralization unit 12c emits the first light 131c to the photosensitive drum 2c (adjacent second image carrier) constituting the image forming unit 15c that is the adjacent second image forming unit, and sensitizes the emitted first light 131c. A region between the position facing the primary transfer position on the body drum 2c and the position facing the cleaning unit 11c is irradiated as the first charge removal light 141c.
The neutralization unit 12c then emits the second light 132c to the photosensitive drum 2d (first image carrier) constituting the image forming unit 15d, which is the first image forming unit, and directly outputs the emitted second light 132c. Alternatively, indirectly (in this embodiment, indirectly reflected by the intermediate transfer belt 7) from a position facing the developing portion 16d (first developing portion) on the photosensitive drum 2d (first image carrier). It is configured to irradiate the region between the position opposite to the primary transfer position as the second charge removal light 142c.

The static eliminating unit 12c is configured to integrally (simultaneously) turn on / off light emitted from the first light 131c and the second light 132c.
As described above, the charge removal unit 12c is controlled by the charge removal control unit 230 to integrally turn on / off the light emitted from the first light 131c and the second light 132c.

The control unit 200 includes a plurality of functional units.
The control unit 200 includes an image formation mode setting unit 210, a printing rate calculation unit 220, a charge removal control unit 230, a calculation unit 240, and a rotation drive control unit 250.

The image forming mode setting unit 210 is configured to be able to set an image forming mode. The image forming mode setting unit 210 is configured to be able to set the image forming mode to a monochrome printing mode (first mode) and a color printing mode (second mode).
For example, the image forming mode setting unit 210 sets the image forming mode to the monochrome printing mode or the color printing mode based on the operation input from the user received by the operation input unit 110.
Further, the image forming mode setting unit 210 sets the image forming mode to a monochrome printing mode or a color printing mode based on mode setting information included in job information, for example.

The printing rate calculation unit 220 is configured to calculate the printing rate in a state where the color printing mode (first mode) is set by the image forming mode setting unit 210.
The printing rate calculation unit 220 calculates the printing rate based on image information stored in a job information storage unit 310 to be described later. The printing rate calculation unit 220 outputs the calculated printing rate information to the charge removal control unit 230.

  The static elimination control unit 230 controls light irradiation (light emission) in the static elimination units 12a, 12b, 12c, and 12d. In particular, the charge removal control unit 230 irradiates the first light and the second light (light emission) in the charge removal unit 12c (adjacent second charge removal) in a state where the image forming mode is set to the monochrome printing mode (first mode). Is integrally controlled.

  In the color printing mode (second mode), the charge removal control unit 230, for example, removes the first light and the second light output (irradiation of the first charge removal light and the second charge removal light) to turn on the charge removal units 12a and 12b. , 12c are controlled.

In the monochrome printing mode (first mode), the static elimination control unit 230 controls to turn off the emission of the first light and the second light in the static elimination units 12a and 12b.
Further, in the monochrome printing mode (first mode), the static elimination control unit 230 integrally controls on / off of light emission in the first light and the second light in the static elimination unit 12c. In the monochrome printing mode (first mode), the static elimination control unit 230 turns on or off the light emission of the first light and the second light in the static elimination unit 12c according to a predetermined condition.

The static elimination control unit 230 controls the static elimination unit 12c based on the printing rate calculated by the printing rate calculation unit 220.
The static elimination control unit 230 turns on the irradiation of the first light 131c (141c) and the second light 132c (142c) when the printing rate calculated by the printing rate calculation unit 220 is equal to or higher than the predetermined printing rate in the monochrome printing mode. The neutralization unit 12c (adjacent second neutralization unit) is controlled so that Then, in the monochrome printing mode, the charge removal control unit 230 emits the first light 131c (141c) and the second light 132c (142c) when the printing rate calculated by the printing rate calculation unit 220 is less than the predetermined printing rate. The neutralization unit 12c (adjacent second neutralization unit) is controlled so as to turn off.

When the monochrome printing mode (first mode) is set by the image forming mode setting unit 210, the calculating unit 240 is between the image forming unit 15d (first image forming unit) and the first transfer position on the intermediate transfer belt 7. The number of sheets T (sheet members) that pass through is calculated.
The calculation unit 240 calculates the number of sheets on which images are formed in one or a plurality of jobs executed continuously in the monochrome printing mode. The calculation unit 240 calculates the number of sheets based on the job information stored in the job information storage unit 310. Here, the calculation unit 240 may be configured to calculate the number of sheets based on a predetermined size (for example, A4 size).

  The rotation drive control unit 250 controls the rotation drive unit 130. The rotation drive control unit 250 controls the rotation drive unit 130 to rotate or stop the rotation of each of the photosensitive drums 2a, 2b, 2c, and 2d. The rotation drive control unit 250 controls the rotation drive unit 130 to rotate each of the photosensitive drums 2a, 2b, 2c, and 2d under predetermined rotation conditions (rotation speed and rotation time).

  In addition, when the rotation driving control unit 250 controls the rotation driving unit 130 to rotate the photosensitive drum 2c (adjacent second image carrier) in the monochrome printing mode, the photosensitive drum 2c (adjacent second imaging unit) is passed after a predetermined time has elapsed. The rotation drive unit 130 is controlled to stop the rotation of the two-image carrier.

  In addition, when the rotation drive control unit 250 controls the rotation drive unit 130 to rotate the photosensitive drum 2c (adjacent second image carrier) in the monochrome printing mode, the rotation speed is lower than the rotation speed in the color printing mode. The rotation drive unit 130 is controlled to rotate the photosensitive drum 2c.

  Further, when the rotation drive control unit 250 controls the rotation drive unit 130 to rotate the photosensitive drum 2c (adjacent second image carrier) in the monochrome printing mode, the first light 131c (the first light 131c at the start of rotation) is controlled. The rotation driving unit 130 is controlled so that the rotation is stopped when the region irradiated with the neutralizing light 141c) is arranged at a position where the first light 131c (first neutralizing light 141c) is not irradiated. In the monochrome printing mode, the rotation drive control unit 250 has a first light 131c (first light 131c (first output)) that is different from the region irradiated with the first light 131c (first charge removal light 141c) on the photosensitive drum 2c at the start of rotation. The rotational drive control unit 250 is controlled so that the rotation is stopped when the static elimination light 141c) is disposed at the position where the static elimination light 141c) is irradiated.

The storage unit 300 stores various programs and various information. The storage unit 300 includes a job information storage unit 310.
The job information storage unit 310 stores one or a plurality of job information. The job information storage unit 310 stores job information including image information and image formation mode information received from an external terminal device via the interface unit 100, for example.

  Next, the operation of the printer 1 will be described with reference to FIG. FIG. 5 is a flowchart for explaining the operation of the printer 1.

  As shown in FIG. 5, in step ST <b> 1, the printer 1 receives job information via the interface unit 100. When the job information includes image formation instruction information, the printer 1 receives an image formation instruction based on the image information included in the job information.

  Subsequently, in step ST2, the printer 1 starts an image forming operation based on the received image forming instruction. For example, the printer 1 (image formation mode setting unit 210) sets the image formation mode based on the mode setting information included in the job information.

Subsequently, in step ST3, the printer 1 determines whether or not the set image forming mode is the monochrome printing mode.
If it is determined that the set image forming mode is the monochrome printing mode (YES in step ST3), the printer 1 advances the process to step ST4.
If it is determined that the set image forming mode is not the monochrome printing mode (determined to be the color printing mode) (NO in step ST3), the printer 1 advances the process to step ST10.

  Subsequently, in step ST4, the printer 1 (print rate calculation unit 220) calculates the print rate based on one or a plurality of job information on which image formation is executed continuously.

Subsequently, in step ST5, the printer 1 determines whether the calculated printing rate is equal to or higher than a predetermined printing rate.
When it is determined that the calculated printing rate is equal to or higher than the predetermined printing rate (step ST5, YES), the printer 1 advances the process to step ST6.
When it is determined that the calculated printing rate is not equal to or higher than the predetermined printing rate (less than the predetermined printing rate) (NO in step ST5), the printer 1 advances the process to step ST7.

  Subsequently, in step ST6, the printer 1 (the charge removal control unit 230) causes the charge removal unit 12c to emit the first light 131c (first charge removal light 141c) and the second light 132c (second charge removal light 142c).

Subsequently, in step ST8, the printer 1 (rotation drive control unit 250, rotation drive unit 130) rotates the photosensitive drum 2c.
Here, in the present embodiment, the printer 1 (rotation drive control unit 250) is configured to rotate the photosensitive drum 2c so as to rotate when the number of sheets calculated by the calculation unit 240 is equal to or greater than a predetermined number. 130 is controlled.
In addition, the printer 1 (rotation drive control unit 250) may control the rotation drive unit 130 to rotate the photosensitive drum 2c at a rotation speed slower than the rotation speed in the color printing mode.

Subsequently, in step ST9, the printer 1 (rotation drive control unit 250) stops the rotation of the photosensitive drum 2c at a predetermined timing.
Here, in the present embodiment, the printer 1 (the rotation drive control unit 250 and the rotation drive unit 130) may stop the rotation of the photosensitive drum 2c after a predetermined time has elapsed from the start of rotation.
Further, in the printer 1 (rotation drive control unit 250), the region irradiated with the first light 131c (first discharge light 141c) at the start of rotation is not irradiated with the first light 131c (first discharge light 141c). The rotation driving unit 130 may be controlled so that the rotation is stopped when the rotation driving unit 130 is disposed.

  Subsequently, in step ST10, when the execution of the job that is the target of the image formation instruction is completed, the printer 1 ends the image forming operation and ends a series of processes.

  In step ST7, the printer 1 (the charge removal control unit 230) does not cause the charge removal unit 12c to emit the first light 131c (first charge removal light 141c) and the second light 132c (second charge removal light 142c). Then, the printer 1 advances the process to step ST10, ends the image forming operation when the execution of the job is ended, and ends a series of processes as described above.

According to the present embodiment, in the monochrome printing mode, the printer 1 performs the first light (first irradiation light) and the second light (second removal) when the printing rate in the image forming unit 15d is equal to or higher than the predetermined printing rate. The static eliminator 12c is controlled to irradiate light.
As a result, the printer 1 is configured to perform static elimination before transfer when the printing rate on the photosensitive drum 2d becomes equal to or higher than a predetermined printing rate that requires static elimination before transfer. As a result, the printer 1 can suppress the emission of unnecessary first light in the charge removal unit 12c, and is configured to be able to suppress deterioration of the photosensitive drum 2c.

Further, according to the present embodiment, the printer 1 calculates (converts) the amount of image formation by the number of sheets in the monochrome printing mode, and when the calculated number is equal to or larger than the predetermined number, the photoconductor The drum 2c is configured to be driven to rotate.
Accordingly, the printer 1 is configured to be able to suppress deterioration of the photosensitive drum 2c caused by intensively irradiating the first light (first neutralizing light) to a predetermined area in the photosensitive drum 2c.

  According to this embodiment, the printer 1 is configured to stop the rotation of the photosensitive drum 2c after a predetermined time when the photosensitive drum 2c is rotationally driven in the monochrome printing mode. Accordingly, the printer 1 is configured to be able to suppress deterioration of the photosensitive drum 2c caused by intensively irradiating a predetermined area of the photosensitive drum 2c with the first light (first charge eliminating light) as described above. Is done. In addition, the printer 1 is configured to be able to suppress an increase in cost, a failure, or the like that occurs when the photosensitive drum 2c continues to rotate more than necessary.

Further, according to the present embodiment, the printer 1 is configured to be able to rotate the photosensitive drum 2c at a rotation speed slower than the rotation speed in the color printing mode in the monochrome printing mode.
Accordingly, the printer 1 is configured to be able to rotate and drive the photosensitive drum 2c at a speed capable of suppressing deterioration due to the first light. Accordingly, the printer 1 is configured to be able to suppress an increase in cost, a failure, and the like caused by rotating the photosensitive drum 2c at a rotational speed faster than necessary.

Further, according to the present embodiment, in the monochrome printing mode, the printer 1 is configured such that the region irradiated with the first light (first irradiation light) at the start of rotation of the photosensitive drum 2c is the first light (first light). It is configured to stop the rotation when it is arranged at a position where it is not irradiated with the irradiation light.
As a result, the printer 1 is configured to be able to suppress intensive deterioration in a predetermined area.

Second Embodiment
Next, a second embodiment will be described. About 2nd Embodiment, a different point from 1st Embodiment is mainly demonstrated, the same code | symbol is attached | subjected about the structure similar to 1st Embodiment, and description is abbreviate | omitted. For the points that are not specifically described in the second embodiment, the description of the first embodiment is applied as appropriate. In the second embodiment, the same effect as that of the first embodiment is achieved.

A printer 1A according to the second embodiment will be described with reference to FIG. FIG. 6 is a block diagram of the printer 1A.
As illustrated in FIG. 6, the printer 1A includes a detection unit 225 in the control unit 200A. In the second embodiment, the control unit 200A includes a detection unit 225 instead of the print rate calculation unit 220 in the first embodiment.
The detection unit 225 forms an image density of an image formed on the photosensitive drum 2d and an image on the photosensitive drum 2d in a state where the monochrome printing mode (first mode) is set by the image forming mode setting unit 210. The image area to be detected is detected.

  Further, the printer 1A includes a charge removal control unit 230A in the control unit 200A. The static elimination control unit 230A controls the static elimination unit similarly to the static elimination control unit 230 in the first embodiment. The charge removal control unit 230A is different from the charge removal control unit 230 in the first embodiment in that the charge removal unit is controlled based on the detection result in the detection unit 225.

In the present embodiment, the charge removal control unit 230A detects that the image density of the predetermined image is equal to or higher than the first density by the detection unit 225, and sets the predetermined image in the same area as the image area formed on the photosensitive drum 2d. When it is detected that the image density of the next image formed continuously with the predetermined image is lower than the second density which is lower than the first density, the irradiation of the first light and the second light is turned on. The neutralization unit 12c (adjacent second neutralization unit) is controlled so as to do so.
For example, in the case where the first density is 80% and the second density is 60%, the charge removal control unit 230A determines that the first light is 100% when the image density of the predetermined image is 50% and the image density of the next image is 50%. And the static elimination part 12c is controlled to turn on irradiation of 2nd light.

When the detection unit 225 detects that the image density of the predetermined image is equal to or higher than the first density, and the charge removal control unit 230A detects that the image density of the next image is higher than the second density, The neutralization unit 12c (adjacent second neutralization unit) is controlled to turn off the irradiation of the first light and the second light.
For example, in the case where the first density is 80% and the second density is 60%, the charge removal control unit 230A determines that the first light is 100% when the image density of the predetermined image is 100% and the image density of the next image is 100%. And the static elimination part 12c is controlled to turn off irradiation of 2nd light.

According to the present embodiment, the printer 1A is configured to emit the first light and the second light from the charge removal unit 12c when the charge removal before transfer is necessary.
Accordingly, the printer 1A is configured to be able to suppress the neutralization unit 12c from emitting the first light more than necessary. As a result, the printer 1A can suppress the emission of unnecessary first light in the static elimination unit 12c, and is configured to be able to suppress deterioration of the photosensitive drum 2c.
In addition, the printer 1A according to the present embodiment has the same effects as the effects according to the first embodiment.

As mentioned above, although preferred embodiment was described, this invention can be implemented with a various form, without being limited to embodiment mentioned above.
For example, in the first embodiment and the second embodiment, the printers 1 and 1A are configured so that the second light emitted from the charge eliminating unit is reflected by the intermediate transfer belt and (indirectly) irradiated on the photosensitive drum. Although configured, it is not limited to this.
For example, as illustrated in FIG. 7, the printer 1 </ b> B may be configured such that the second light emitted from the static elimination unit is directly irradiated onto the photosensitive drum.

  Further, in the first embodiment and the second embodiment, the switching drive unit is configured to move the image forming units 15a, 15b, and 15c, but is not limited thereto. For example, the switching drive unit may be configured to deform the transfer belt (for example, move one end side of the transfer belt in the vertical direction).

  The type of the image forming apparatus of the present invention is not particularly limited, and may be a color copier, a facsimile, or a complex machine of these in addition to a printer.

DESCRIPTION OF SYMBOLS 1 ... Printer (image forming apparatus), 2a, 2b, 2c ... Photoconductor drum (second image carrier), 2d ... Photoconductor drum (first image carrier), 4a, 4b, 4c, 4d ... ... laser scanner unit, 7 ... intermediate transfer belt, 10a, 10b, 10c, 10d ... charging unit, 11a, 11b, 11c, 11d ... cleaning unit, 12a, 12b ... static elimination unit (second static elimination unit), 12c: Static elimination section (adjacent second static elimination section), 12d: Static elimination section (first neutralization section), 15 ... Image forming unit group, 15a, 15b ... Image forming unit (second image forming unit), 15c ... Image forming unit (adjacent second image forming unit), 15d... Image forming unit (first image forming unit), 16a, 16b, 16c... Developing unit, 16d .. developing unit (first developing unit), 20. ... be Cleaning unit 131a, 131b, 131c, 131d ... first light, 132a, 132b, 132c, 132d ... second light, 141a, 141b, 141c, 141d ... first static elimination light, 142a, 142b, 142c ... ... second static elimination light, X ... main scanning direction, Y ... sub-scanning direction, Z ... vertical direction

Claims (6)

A plurality of image forming units arranged at intervals in the rotation direction of the intermediate transfer belt, the image carrier, and a downstream side in the rotation direction of the intermediate transfer belt from a position where the image carrier and the intermediate transfer belt face each other In an image forming apparatus including an image forming unit group composed of a plurality of image forming units each having a charge eliminating portion disposed in
An image forming mode setting section capable of setting an image forming mode;
A switching drive unit that performs switching driving based on the mode set by the image forming mode setting unit;
When set to the first mode,
In the image forming unit group, the first image forming unit disposed at a predetermined position excluding the most upstream side in the rotation direction of the intermediate transfer belt is disposed at a first transfer position contacting the primary transfer position, and A plurality of second image forming units different from the first image forming unit in the image forming unit group are arranged at a second non-transfer position separated from the primary transfer position,
When set to the second mode,
A switching drive unit for disposing the first image forming unit at the first transfer position and disposing the plurality of second image forming units at a second transfer position contacting the primary transfer position;
A printing rate calculation unit that calculates a printing rate in a state where the first mode is set by the image forming mode setting unit;
A charge removal control unit that controls light irradiation in the plurality of charge removal units,
Among the plurality of second image forming units, in an adjacent second image forming unit disposed adjacent to the upstream side with respect to the first image forming unit in the rotation direction of the intermediate transfer belt,
The adjacent second charge eliminating unit constituting the adjacent second image forming unit is:
The first light is emitted to the side of the adjacent second image carrier constituting the adjacent second image forming unit, and the emitted first light is directed to the position facing the primary transfer position of the adjacent second image carrier. While irradiating the downstream region in the rotation direction of the adjacent second image carrier as the first static elimination light,
A position where the second light is emitted toward the first image carrier constituting the first image forming unit, and the emitted second light is directly or indirectly opposed to the primary transfer position on the first image carrier. Is configured to irradiate the upstream region in the rotation direction of the first image carrier as the second static elimination light,
The static elimination control unit
The irradiation of the first light and the second light in the adjacent second static elimination unit is controlled to be simultaneously turned on or simultaneously turned off ,
When the printing rate calculated by the printing rate calculation unit is equal to or higher than a predetermined printing rate, the adjacent second charge removal unit is controlled to simultaneously turn on the irradiation of the first light and the second light,
An image forming apparatus that controls the adjacent second charge eliminating unit to simultaneously turn off the irradiation of the first light and the second light when the printing rate calculated by the printing rate calculating unit is less than a predetermined printing rate. A plurality of image forming units arranged at intervals in the rotation direction of the intermediate transfer belt, the image carrier, and a downstream side in the rotation direction of the intermediate transfer belt from a position where the image carrier and the intermediate transfer belt face each other In an image forming apparatus including an image forming unit group composed of a plurality of image forming units each having a charge eliminating portion disposed in
An image forming mode setting section capable of setting an image forming mode;
A switching drive unit that performs switching driving based on the image forming mode set by the image forming mode setting unit;
When set to the first mode,
In the image forming unit group, the first image forming unit disposed at a predetermined position excluding the most upstream side in the rotation direction of the intermediate transfer belt is disposed at a first transfer position contacting the primary transfer position, and A plurality of second image forming units different from the first image forming unit in the image forming unit group are arranged at a second non-transfer position separated from the primary transfer position,
When set to the second mode,
A switching drive unit for disposing the first image forming unit at the first transfer position and disposing the plurality of second image forming units at a second transfer position contacting the primary transfer position;
A detection unit for detecting an image density of an image formed on the image carrier and an image area in a state where the first mode is set by the image formation mode setting unit;
A charge removal control unit that controls light irradiation in the plurality of charge removal units,
Among the plurality of second image forming units, in an adjacent second image forming unit disposed adjacent to the upstream side with respect to the first image forming unit in the rotation direction of the intermediate transfer belt,
The adjacent second charge eliminating unit constituting the adjacent second image forming unit is:
The first light is emitted to the side of the adjacent second image carrier constituting the adjacent second image forming unit, and the emitted first light is directed to the position facing the primary transfer position of the adjacent second image carrier. While irradiating the downstream region in the rotation direction of the adjacent second image carrier as the first static elimination light,
A position where the second light is emitted toward the first image carrier constituting the first image forming unit, and the emitted second light is directly or indirectly opposed to the primary transfer position on the first image carrier. Is configured to irradiate the upstream region in the rotation direction of the first image carrier as the second static elimination light,
The static elimination control unit
The irradiation of the first light and the second light in the adjacent second static elimination unit is controlled to be simultaneously turned on or simultaneously turned off ,
The detection unit detects that the image density of the predetermined image is equal to or higher than the first density, and the predetermined image is continuously formed on the predetermined image in the same area as the image area formed on the image carrier. If the image density of the next image is detected to be lower than the second density, which is lower than the first density, the adjacent first and second light irradiations are simultaneously turned on. 2 Control the static neutralizer,
When the detection unit detects that the image density of the predetermined image is equal to or higher than the first density and the image density in the next image is detected to be higher than the second density, the first light and the first light An image forming apparatus that controls the adjacent second static elimination unit to simultaneously turn off the irradiation of two lights. A rotation drive unit for rotating and driving each of the plurality of image carriers;
A rotation drive control unit for controlling the rotation drive unit;
A calculating unit that calculates the number of sheet members that pass between the first image forming unit and the first transfer position of the intermediate transfer belt when the first mode is set by the image forming mode setting unit; Have
When the adjacent second static elimination unit is controlled by the static elimination control unit to simultaneously turn on the irradiation of the first light and the second light,
The rotational drive controller is
When the number of sheets calculated by the calculation unit is a predetermined number or more, the rotation driving unit is controlled to rotate the adjacent second image carrier,
3. The image forming apparatus according to claim 1, wherein when the number calculated by the calculation unit is less than the predetermined number, the rotation driving unit is controlled so as not to rotate the adjacent second image carrier. The rotational drive controller is
4. The image according to claim 3, wherein when the rotation drive unit is controlled to rotate the adjacent second image carrier, the rotation drive is controlled to stop the rotation of the adjacent second image carrier after a predetermined time has elapsed. Forming equipment. The rotational drive controller is
When the rotation drive unit is controlled to rotate the adjacent second image carrier, the rotation drive unit is controlled to rotate the adjacent second image carrier at a rotation speed slower than the rotation speed in the second mode. The image forming apparatus according to claim 3 or 4. The rotational drive controller is
When the rotation driving unit is controlled to rotate the adjacent second image carrier, the region irradiated with the first light at the start of rotation is rotated when the region is not irradiated with the first light. The image forming apparatus according to claim 3, wherein the rotation driving unit is controlled to stop the rotation.

Images