JP2018180278A - Image forming apparatus and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus which is an image forming apparatus including a plurality of image forming parts and is capable of suitably keeping the service life balance of an image carrier and a cleaning member and to provide a program.SOLUTION: The image forming apparatus includes an intermediate transfer belt 451 and a plurality of image forming devices arranged in the rotational direction of the intermediate transfer belt. The image forming device includes a photoreceptor drum 41 which carries a toner image transferred to a paper sheet, an electrifying device 42 which electrifies the photoreceptor drum, a developing device 44 which supplies toner to the photoreceptor drum, to develop the toner image, a lubricant application mechanism 47 which supplies a lubricant having a polarity reverse to that of the toner supplied by the developing device to the photoreceptor drum, and a cleaning blade which comes into contact with the photoreceptor drum, to clean its surface. A lubricant supply amount in the lubricant application mechanism of one image forming device arranged at the most upstream side in the rotational direction of the intermediate transfer belt is smaller than a lubricant supply amount in the lubricant supply and application mechanisms of the other image forming devices.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an image forming apparatus and a program.

  Heretofore, as a means for removing residual toner such as non-transfer toner and transfer residual toner on an image carrier in an electrophotographic image forming apparatus, for example, a cleaning member such as a flat cleaning blade made of an elastic body A blade cleaning type cleaning device is known which abuts against the surface of an image carrier to remove residual toner on the image carrier.

  In recent years, there is a demand for reducing the particle diameter of toner particles from the viewpoint of achieving high image quality in an electrophotographic image forming apparatus, and as a method for obtaining such toner particles, for example, emulsion polymerization, suspension polymerization, etc. Polymerization method is used. However, since the adhesion between the toner particles and the image carrier increases as the toner particles become smaller, it becomes difficult to remove the residual toner on the image carrier. In particular, when a so-called polymerized toner produced by a polymerization method is used, the shape of the toner particles becomes nearly spherical, and a cleaning defect called a "slip mark" that easily passes through the cleaning blade tends to occur. There is a problem that the removal of the residual toner on the carrier becomes more difficult. Furthermore, toner aggregates may be formed on the image carrier with the toner that has slipped through the cleaning blade as a core, and granular white spots (granular noise) may occur in the solid image printed portion.

In order to cope with quality problems such as "slip noise" and "granular noise", at present, a lubricant is supplied onto the image carrier to perform cleaning in a state in which the adhesion between toner particles and the image carrier is reduced. (See, for example, Patent Document 1). As a method of supplying a lubricant onto the image carrier, a brush is brought into contact with a rod-like lubricant, the lubricant is scraped off by the brush, and a lubricant application system supplied onto the surface of the image carrier or a toner image is formed by toner containing lubricant. And a toner external addition system for supplying a lubricant.
If the amount of lubricant on the image carrier is small, there occur quality problems such as the above-mentioned "slip noise" and "granular noise" and the problem that the wear of the image carrier becomes large and the life of the image carrier becomes short. On the other hand, when the amount of the lubricant on the image carrier is too large, there is a problem that the abrasion of the cleaning blade is increased, so that the amount of lubricant on the latent image carrier has an appropriate range.
The lubricant on the image carrier is recovered by a cleaning blade or the like, and the amount of recovery varies depending on the amount of toner deposited on the cleaning blade, so that even if a certain amount of lubricant is supplied onto the image carrier, the image carrier The amount of lubricant above varies.
Therefore, in order to maintain the amount of lubricant on the image carrier within an appropriate range, it is necessary to control the amount of lubricant supplied and recovered.

JP 9-62163 A

When a lubricant having the same polarity as that of the toner is supplied to the image carrier, the lubricant may move to the intermediate transfer belt by the transfer electric field. In the case of a color image forming apparatus in particular, the amount of lubricant decreases as the image forming unit located downstream decreases because the transfer electric field must be increased as the image forming unit located downstream.
On the other hand, when the charge polarity of the lubricant is reverse to that of the toner, the transfer of the lubricant to the intermediate transfer belt does not occur, so there is no concern of the shortage of the lubricant.

However, in some cases, “reverse transfer” may occur in which the toner of the upstream color transferred to the intermediate transfer belt is re-transferred onto the image carrier of the downstream color, and the amount of toner reaching the cleaning blade is the transfer residue of its own color. In addition to the toner amount, the upstream reverse transfer toner amount is also added. As a result, since the amount of toner reaching the cleaning blade is increased, the recovery of the lubricant by the cleaning blade is promoted, and the amount of lubricant in the downstream color is further reduced.
Therefore, in the case of a color machine, even if a lubricant having a polarity opposite to that of the toner is used, the amount of the lubricant on the downstream of the image carrier is reduced by the influence of the reverse transfer toner of the upstream color. Since the amount of lubricant on the image carrier has an appropriate range, the amount of lubricant on the image carrier for each color needs to be within a certain range, and for that purpose, the lubricant on the downstream image carrier with a large recovery amount It is necessary to increase the supply volume. If the lubricant supply amount is the same as that of the downstream color even on the topmost color image carrier in which no reverse transfer toner is present, oversupply will occur. As a result, there arises a problem that the life of the most upstream cleaning blade is shortened.

  The present invention has been made in view of the above problems, and provides an image forming apparatus and program capable of making the life balance of an image carrier and a cleaning member suitable in an image forming apparatus having a plurality of image forming units. The purpose is to

In order to solve the above problems, the image forming apparatus according to claim 1 is:
An intermediate transfer member for transferring a toner image to paper;
A plurality of imaging devices disposed along the rotational direction of the intermediate transfer member,
The imaging device
An image carrier that carries a toner image to be transferred to a sheet;
A charging device for charging the image carrier;
A developing device that supplies toner to the image carrier and develops a toner image;
And a cleaning member disposed downstream of the transfer position with the intermediate transfer member and upstream of the charging device in the rotational direction of the image carrier and cleaning the surface by coming into contact with the image carrier.
A lubricant having a polarity opposite to that of the toner supplied by the developing device is supplied to the image carrier.
The lubricant supply amount to the image carrier of one imaging device disposed on the most upstream side in the rotational direction of the intermediate transfer member is smaller than the lubricant supply amount to the image carrier of the other imaging device. It is characterized by

The invention according to claim 2 is the image forming apparatus according to claim 1,
A lubricant supply device disposed downstream of the transfer position with the intermediate transfer member in the rotation direction of the image carrier and supplying the lubricant to the image carrier;
A controller for controlling the lubricant supply amount in the lubricant supply device;
The lubricant supply device
A solid lubricant, and a rotating member that rotates in contact with the image carrier and the solid lubricant;
The control unit
The contact force of the solid lubricant to the rotary member in the lubricant supply device of the one imaging device is controlled to be weaker than the contact force of the solid lubricant to the rotary member in the lubricant supply device of another imaging device It is characterized by

The invention according to claim 3 is the image forming apparatus according to claim 1 or 2
A lubricant supply device disposed downstream of the transfer position with the intermediate transfer member in the rotation direction of the image carrier and supplying the lubricant to the image carrier;
A controller for controlling the lubricant supply amount in the lubricant supply device;
The lubricant supply device
A solid lubricant, and a rotating member that rotates in contact with the image carrier and the solid lubricant;
The control unit
The rotation number of the rotating member in the lubricant supplying device of the one imaging device is controlled to be smaller than the rotation number of the rotating member in the lubricant supplying device of the other image forming device.

The invention according to a fourth aspect is the image forming apparatus according to the first aspect, wherein
A lubricant supply device disposed downstream of the transfer position with the intermediate transfer member in the rotation direction of the image carrier and supplying the lubricant to the image carrier;
A controller for controlling the lubricant supply amount in the lubricant supply device;
The lubricant supply device
A solid lubricant, and a pressing member for pressing the solid lubricant against the image carrier;
The control unit
The pressing force of the pressing member in the lubricant supplying device of the one imaging device is controlled to be smaller than the pressing force of the pressing member in the lubricant supplying device of the other imaging device.

The invention according to claim 5 is the image forming apparatus according to any one of claims 2 to 4 in which
The control unit
The lubricant supply amount in the lubricant supplying device of the other imaging device is controlled based on the transfer voltage in the imaging device and the image area ratio of the toner image formed by at least the one imaging device. It is characterized by

The invention according to claim 6 is the image forming apparatus according to any one of claims 2 to 5,
The imaging device
A measurement unit configured to measure an amount of toner transferred from the intermediate transfer body to the image carrier;
The control unit
The lubricant supply amount in the lubricant supplying device of the other imaging device, the toner amount measured by the measuring unit in the imaging device, and the image area ratio of the toner image formed in at least one of the one imaging device And control based on and.

The invention according to claim 7 is the image forming apparatus according to any one of claims 2 to 6,
The control unit may control the lubricant supply amount of the image forming apparatus disposed upstream in the rotational direction of the intermediate transfer member so as to reduce the lubricant supply amount.

The invention according to claim 8 is the image forming apparatus according to any one of claims 2 to 7 in which
The lubricant supply device comprises a solid lubricant,
It is characterized in that the hardness of the solid lubricant in the lubricant supplying device of the one imaging device is higher than the hardness of the solid lubricant in the lubricant supplying device of the other imaging device.

The invention according to claim 9 relates to the image forming apparatus according to claim 8.
It is characterized in that the hardness of the solid lubricant is higher as the lubricant supplying device of the image forming device disposed upstream in the rotational direction of the intermediate transfer member.

The invention according to claim 10 relates to the image forming apparatus according to claim 1.
The developing device supplies a toner to which a lubricant is added to the image bearing member,
The amount of lubricant added to the toner in one imaging device disposed on the most upstream side in the rotational direction of the intermediate transfer member is smaller than the amount of lubricant added to the toner in the other imaging device. .

The invention according to claim 11 is the image forming apparatus according to claim 10,
It is characterized in that the amount of the lubricant added to the toner is smaller as the image forming apparatus disposed upstream in the rotational direction of the intermediate transfer member.

The program according to claim 12 is
An intermediate transfer body for transferring a toner image onto a sheet of paper, and a plurality of image forming devices arranged along the rotational direction of the intermediate transfer body, the image forming device carrying a toner image to be transferred onto a sheet of paper An image carrier, a charging device for charging the image carrier, a developing device for supplying a toner to the image carrier and developing a toner image, and a transfer with the intermediate transfer member in the rotation direction of the image carrier A cleaning member disposed downstream of the position and upstream of the charging device and in contact with the image carrier to clean the surface, and downstream of the transfer position with the intermediate transfer member in the rotational direction of the image carrier And b) a lubricant supply device arranged to supply a lubricant to the image carrier.
The lubricant supply amount in the lubricant supplying device of one imaging device disposed on the most upstream side in the rotational direction of the intermediate transfer member is controlled to be smaller than the lubricant supplying amount in the lubricant supplying device of the other imaging device. Function as a control unit.

  According to the present invention, in an image forming apparatus having a plurality of image forming units, it is possible to provide an image forming apparatus and a program capable of making the life balance of the image carrier and the cleaning member suitable.

FIG. 1 is a view showing a schematic configuration of an image forming apparatus according to an embodiment to which the present invention is applied. FIG. 2 is a block diagram showing the main functional configuration of the image forming apparatus. FIG. 2 is a diagram showing an example of a schematic configuration of an image forming unit. FIG. 6 is a view showing an example of a vertical band chart formed on a photosensitive drum. It is a figure explaining the amount of lubricants on a photoreceptor drum. FIG. 6 is a view for explaining reverse transfer toner attached on a photosensitive drum. It is a figure explaining the abrasion loss of the cleaning blade in each image formation part. It is a figure explaining the wear width of a cleaning blade. It is a figure explaining the control method of the contact | abutting force of a brush roller. FIG. 2 is a view of a lubricant application mechanism as viewed from the circumferential direction of a photosensitive drum. FIG. 2 is a diagram showing an example of a schematic configuration of an image forming unit. FIG. 6 is a view for explaining the relationship between the image area ratio of the upstream color and the reverse transfer toner. It is a flowchart which shows operation | movement of the image forming apparatus which concerns on embodiment to which this invention is applied. FIG. 6 is a view showing an example of an image forming unit in which a density sensor is arranged. FIG. 2 is a diagram showing an example of a schematic configuration of an image forming unit. FIG. 2 is a diagram showing an example of a schematic configuration of an image forming unit.

First Embodiment
Hereinafter, a first embodiment according to an image forming apparatus of the present invention will be described based on the drawings. Although the embodiment of the present invention will be described by taking a color image forming apparatus as an example, the present invention is not limited to this, and the present invention is applied to an image forming apparatus having a plurality of image forming units. It is possible.

<Configuration of Image Forming Apparatus>
FIG. 1 is a view showing a schematic configuration of an image forming apparatus 1 according to an embodiment of the present invention. FIG. 2 is a block diagram showing the main functional configuration of the image forming apparatus 1.

  As shown in FIGS. 1 and 2, the image forming apparatus 1 includes an automatic document feeder 2, a scanner 3, an image forming unit 4, a sheet feeder 5, a storage 6, and an operation display 7. The control unit 10 is configured.

The automatic document conveyance unit 2 includes a placement tray for placing the document D, a mechanism for conveying the document D, a conveyance roller, and the like, and conveys the document D to a predetermined conveyance path.
The scanner unit 3 includes an optical system such as a light source and a reflecting mirror, irradiates the light source to the document D conveyed on a predetermined conveyance path or the document D placed on a platen glass, and receives reflected light. . Further, the scanner unit 3 converts the received reflected light into an electrical signal and outputs the electrical signal to the control unit 10.

FIG. 3 shows a schematic configuration of the image forming unit 4.
As shown in FIG. 1, the image forming unit 4 includes a yellow image forming unit Y, a magenta image forming unit M, a cyan image forming unit C, and a black image forming unit K from the upstream side in the rotational direction of the intermediate transfer belt 451. And a fixing device F.

Each image forming unit (image forming device) is a drum-shaped photosensitive drum 41 (image carrier) rotationally driven in the direction of a in the figure, and a charging device for uniformly charging the surface of the photosensitive drum 41 42, an exposure device 43 which exposes the surface of the photosensitive drum 41 charged by the charging device 42 to form an electrostatic latent image, and the electrostatic latent image formed by the exposure device 43 contains toner. The developing device 44 for visualizing using the developer 442, the transfer device 45 for transferring the toner image formed on the photosensitive drum 41 to a sheet, and the toner on the photosensitive drum 41 that has passed through the transfer area A cleaning blade 46 (cleaning member) to be removed and a lubricant application mechanism 47 (lubricant supply device) for applying a lubricant to the surface of the photosensitive drum 41 are provided, and the toner image formed on the photosensitive drum 41 is shown in FIG. direction of b The intermediate transfer belt 451 to be moved to the primary transfer in (intermediate transfer member).
The toner image transferred to the intermediate transfer belt 451 is transferred to the recording material at a secondary transfer position (not shown), and then conveyed to the fixing device F and fixed on the recording medium.

  The photosensitive drum 41 is made of, for example, an organic photosensitive member in which a photosensitive layer made of a resin containing an organic photoconductor is formed on the outer peripheral surface of a drum-shaped metal base, and polycarbonate is used as a resin constituting the photosensitive layer. Resin, silicone resin, polystyrene resin, acrylic resin, methacrylic resin, epoxy resin, polyurethane resin, vinyl chloride resin, melamine resin, etc. may be mentioned.

As the charging device 42, a charging roller or a noncontact charger can be used. A power supply (not shown) is connected to the charging device 42, and the photosensitive drum 41 is charged to a constant potential by a voltage output from the power supply. A driving motor (not shown) is attached to the charging device 42, and the charging device 42 rotates in the with direction (the direction in which the surface moves in the same direction, the direction c in the drawing) while contacting the photosensitive drum 41. , Functions as a rotating member. The circumferential speed of the charging device 42 during image formation is equal to the circumferential speed of the photosensitive drum 41.
After charging by the charging device 42, an electrostatic latent image is formed on the surface of the photosensitive drum 41 by an exposure device 43 such as a laser.

The developing device 44 includes a developing sleeve 441 disposed so as to face the photosensitive drum 41 via the developing area, and a developer 442.
For example, a DC developing bias having the same polarity as the charging polarity of the charging device 42 or a developing bias in which a DC voltage having the same polarity as the charging polarity of the charging device 42 is superimposed on the developing sleeve 441 is applied. Thus, reversal development is performed in which toner is attached to the electrostatic latent image formed by the exposure device 43.
The developer 442 includes a toner and a carrier for charging the toner. The toner is not particularly limited, and commonly known toners can be used, and the binder resin may contain a colorant and, if necessary, a charge control agent, a release agent, etc. It is possible to use one that has been treated with an agent. The toner particle size is not limited to this, but about 3 to 15 μm is preferable. It does not specifically limit as a carrier, The well-known carrier generally used can be used and a binder type | mold carrier, a coating type carrier, etc. can be used. The carrier particle size is not limited to this, but is preferably 15 to 100 μm.

  The toner image formed on the photosensitive drum 41 by the developing device 44 is conveyed to a transfer device 45 provided with an intermediate transfer belt 451 and a transfer roller 452. In the transfer device 45, a voltage having a polarity opposite to that of the toner is applied to the transfer roller 452, and the toner image on the photosensitive drum 41 is primarily transferred to the intermediate transfer belt 451 and then secondarily transferred to paper.

The toner remaining on the photosensitive drum 41 without being transferred to the intermediate transfer belt 451 by the transfer device 45 is conveyed to the cleaning blade 46 and collected. As the cleaning blade 46, a flat blade made of an elastic material is used.
The photosensitive drum 41 from which the toner on the surface has been collected by the cleaning blade 46 is again charged by the charging roller 42, and the next electrostatic latent image is formed to repeat forming a toner image.

A lubricant application mechanism 47 for applying a lubricant to the photosensitive drum 41 is installed downstream of the contact portion with the intermediate transfer belt 451 and upstream of the cleaning blade 46 in the rotational direction of the photosensitive drum 41. . The lubricant applying mechanism 47 includes at least a brush roller 471 (rotating member) and a solid lubricant 472. The solid lubricant 472 has a reverse polarity to that of the toner.
The brush roller 471 is disposed in contact with both the solid lubricant 472 and the photosensitive drum 41, is rotationally driven by a motor (not shown), and supplies lubricant particles scraped out of the solid lubricant 472 to the photosensitive drum 41. At that time, it also plays the role of spreading the lubricant particles on the photosensitive drum 41 by the contact pressure.

  The rotational speed of the brush roller 471 is controlled by changing the rotational speed of a motor (not shown) that rotationally drives the brush roller 471. When the number of rotations is increased, the coating amount is increased, and when it is decreased, the coating amount is decreased. When the number of revolutions is increased, the amount of toner and external additive collected from the photosensitive drum 41 is increased, and when it is decreased, the amount of toner and external additive collected is reduced.

As a material of the solid lubricant 472, a material that can be applied to the surface of the photosensitive drum 41 and reduce the surface energy thereof to reduce the adhesion between the toner and the photosensitive drum 41 is selected. When negatively charged toners are used, fatty acid metal salts, fatty acid amides and the like can be mentioned as positively charged lubricants of reverse polarity, and these can be used alone or in combination of two or more. In particular, fatty acid metal salts are preferred.
As the fatty acid metal salt, as the fatty acid, linear hydrocarbons are preferable. For example, myristic acid, palmitic acid, stearic acid, oleic acid and the like are preferable, and stearic acid is more preferable. Examples of the metal include lithium, magnesium, calcium, strontium, zinc, cadmium, aluminum, cerium, titanium, iron and the like. Among these, zinc stearate, magnesium stearate, aluminum stearate, iron stearate and the like are preferable, and in particular, zinc stearate is most preferable.
In the case of using a positively charged toner, a negatively charged lubricant is used. In this case, a fluorocarbon resin lubricant may be used.
The material described above is melted and molded, or particles of the material are compression molded to prepare a shape that can be scraped off by the brush roller 471 and used as a solid lubricant 472.

  In the present embodiment, the brush roller 471 is further provided in contact with a collection roller 473 composed of a roller, and the brush roller 471 collects the toner collected from the photosensitive drum 41 before reaching the solid lubricant 472. . With such a configuration, the toner on the photosensitive drum 41 can be collected by the rotation of the brush roller 471, and the lubricant can be supplied onto the photosensitive drum 41.

  The sheet feeding unit 5 includes a plurality of sheet feeding trays 51 to 53, and accommodates a plurality of sheets P of different types in the sheet feeding trays 51 to 53. The sheet feeding unit 5 feeds, to the image forming unit 4, the sheet P accommodated by a predetermined conveyance path.

  The storage unit 6 includes a hard disk drive (HDD), a semiconductor memory, and the like, and stores data such as program data and various setting data in a readable and writable manner from the control unit 10. In addition, the storage unit 6 stores a predetermined range of the current value of the drive motor M, which is set in advance, which will be described later.

The operation display unit 7 is configured by, for example, a liquid crystal display (LCD) with a touch panel, and functions as a display unit 71 and an operation unit 72.
The display unit 71 displays various operation screens, the operation status of each function, and the like in accordance with the display control signal input from the control unit 10. Also, it receives a touch operation by the user and outputs an operation signal to the control unit 10.
The operation unit 72 includes various operation keys such as a ten key, a start key, and the like, receives various input operations by the user, and outputs an operation signal to the control unit 10. The user can operate the operation display unit 7 to perform settings relating to image formation such as image quality setting, magnification setting, application setting, output setting and sheet setting, sheet conveyance instruction, and stop operation of the apparatus.

  The control unit 10 is configured to include a CPU, a RAM, a ROM, etc., and the CPU develops various programs stored in the ROM in the RAM, and cooperates with the expanded various programs to execute the automatic document feeder 2. Operations of respective units of the image forming apparatus 1 such as the scanner unit 3, the image forming unit 4, the sheet feeding unit 5, the storage unit 6, the operation display unit 7 and the like are comprehensively controlled (see FIG. 2). For example, the control unit 10 inputs an electrical signal from the scanner unit 3 to perform various image processing, and outputs the image data Dy, Dm, Dc, Dk of each color of YMCK generated by the image processing to the image forming unit 4 . Further, the control unit 10 controls the operation of the image forming unit 4 to form an image on the sheet P.

<Lubricant amount on photosensitive drum>
Next, the amount of lubricant on the photosensitive drum 41 in the downstream color unit will be described.

FIG. 4 is a schematic view of the surface of the photosensitive drum 41 for passing a sheet in the X direction. A black vertical band chart (position indicated by black solid part Ba; B) and a vertical band chart (position indicated by yellow solid part Ya; C) are formed in the axial direction (Y direction) of the photosensitive drum 41, A3 3000 sheets of paper were printed.
The results of examining the amount of lubricant on the photosensitive drum 41 of the most downstream color (black image forming portion B) at this time are shown in FIG. FIG. 6 shows the state of toner present on the photosensitive drum 41 of the black image forming unit B when the apparatus is forcibly stopped while printing the same chart.

An image formed by using a bizhub PRESS C1100 manufactured by Konica Minolta Co., Ltd. as the image forming apparatus 1 and having a brush roller 471, a solid lubricant 472 and a recovery roller 473 provided upstream of the cleaning blade 46 as shown in FIG. The experiment was performed using the part.
The brush roller 471 was made of PET fiber. Further, the recovery roller 473 is GND and the brush roller 471 is float. The surface of the brush roller 471 rotates in the same direction as the photosensitive drum 41 at a peripheral speed of 640 mm / s. As the developer 442, a toner for bizhub PRESS C1100 was used.

The lubricant amount on the photosensitive drum 41 of the black image forming portion B is as follows: position A: background portion (no printing) for both yellow and black, position B: yellow background portion, black solid portion Ba, C position: yellow solid portion Ya, The black background was measured.
The amount of lubricant was substituted by the ratio of zinc in zinc stearate determined by X-ray photoelectron spectroscopy.

  As apparent from FIG. 5, the amount of lubricant at position A where neither black nor yellow is printed is the largest at about 2 at%. On the other hand, the amount of lubricant at position B where black is printed is reduced to 1.6 at%. It is considered that this is because the lubricant is recovered by the cleaning blade 46 by the black transfer residual toner. At position C, the amount of lubricant is reduced although black is not printed. It is considered that this is because the yellow toner is reversely transferred to the photosensitive drum 41 of the black imaging portion B, reaches the cleaning blade 46 of the black imaging portion B, and collects the lubricant. The generation mechanism of the reverse transfer toner will be described later.

In order to confirm this, the power of bizhub PRESS C1100 was turned off while printing the same image, and the state of toner adhesion on the photosensitive drum 41 of the black image forming unit B when forced to stop was observed. . As a result, as shown in FIG. 6, on the photosensitive drum 41 of the black image forming unit B, the transfer residual toner Bb at the B position downstream of the transfer position T in the X direction and the yellow reverse transfer toner Yc at the C position. confirmed.
From these results, it can be seen that the amount of lubricant on the downstream color photosensitive drum 41 is affected by the upstream color reverse transfer toner.

<Control of lubricant supply amount in each imaging unit>
In FIG. 7, after printing 50000 sheets of charts each having an image area ratio of 50% with the same lubricant supply amount (downstream color and an amount capable of securing the appropriate lubricant amount on the photosensitive drum 41) in each image forming unit. The results of measuring the amount of wear of the cleaning blade 46 are shown. As the image forming apparatus 1, the same bizhub PRESS C1100 as used in the measurement of the lubricant amount on the photosensitive drum 41 described above was used. The amount of wear of the cleaning blade 46 is measured at five points in the axial direction of the photosensitive drum 41 and averaged.
The amount of wear of the cleaning blade 46 was measured using a laser microscope VK-X100 manufactured by Keyence Corporation, and the abraded area at the contact position between the photosensitive drum 41 and the cleaning blade 46 as shown in FIG. Refers to the width W of

  As apparent from FIG. 7, when the lubricant supply amount is made the same, it can be understood that the wear amount of the cleaning blade 46 of the yellowish image forming portion Y which is the most flowable color is large. This is considered to be because the reverse transfer toner is not generated in the most upstream yellow image forming portion Y, and the amount of toner reaching the cleaning blade 46 is smaller than that of the downstream color, so the amount of lubricant collected is reduced. If the same amount of lubricant as that of the downstream color is supplied in this state, it is considered that the amount of lubricant on the photosensitive drum 41 is increased and the wear of the cleaning blade 46 is increased. If this happens, the life of the yellow unit will be shortened.

  In order to prevent this, it is necessary to make the amount of lubricant supplied smaller than that of the downstream color, in the most upstream yellow image forming portion Y where no reverse transfer toner is generated. Since only the most upstream color is not affected by the reverse transfer toner, the lubricant supply amount of at least the most upstream color image forming portion should be smaller than the lubricant supply amounts of other colors.

The lubricant supply amount to the photosensitive drum 41 can be changed by controlling the contact force of the solid lubricant 472 with the brush roller 471.
When the contact force is increased, the amount of lubricant scraped from the solid lubricant 472 by the brush roller 471 increases, and as a result, the amount of lubricant supplied to the photosensitive drum 41 also increases. Conversely, when the contact force of the solid lubricant 472 with the brush roller 471 is reduced, the amount of lubricant supplied to the photosensitive drum 41 can be reduced. Therefore, in order to make the lubricant supply amount of the most upstream color image forming portion smaller than that of the downstream color, the contact force of the solid lubricant 472 against the brush roller 471 of the most upstream color image forming portion is smaller than the contact force of the downstream color do it.

A method of controlling the contact force of the solid lubricant 472 is shown in FIGS.
FIG. 10 is a view of the brush roller 471 as viewed from the axial direction, and FIG. 10 is a view of the state of FIG. 9 as viewed from the circumferential direction of the brush roller 471.
FIG. 9A shows a state in which the pressure contact force of the solid lubricant 472 against the brush roller 471 is weakened, and FIG. 9B shows a state in which the pressure contact force is intensified.
The solid lubricant 472 is held by the holding member 474a, and the holding member 474a is guided by the guide 474b and slides along the guide 474b. The solid lubricant 472 is brought into contact with the brush roller 471 by the force of the spring 474c. One end of the spring 474c is in contact with the eccentric cam 474d, and the set length of the spring 474c is changed by the rotation of the eccentric cam 474d, and the pressing force of the solid lubricant 472 to the brush roller 471 is changed. The spring 474c and the eccentric cam 474d are provided on both sides in the axial direction of the brush roller 471 as shown in FIG. 10, and uniformly contact the solid lubricant 472 with the brush roller 471.

  When the eccentric cam 474d is in the position as shown in FIG. 9A, the set length of the spring 474c becomes long, and the pressing force of the solid lubricant 472 against the brush roller 471 becomes weak. As a result, the amount of lubricant that the brush roller 471 scrapes from the solid lubricant 472 decreases, and the amount of lubricant supplied onto the photosensitive drum 41 also decreases. When the eccentric cam 474d is in the position as shown in FIG. 9B, the set length of the spring 474c becomes short, and the pressing force of the solid lubricant 472 against the brush roller 471 becomes strong. As a result, the amount of lubricant that the brush roller 471 scrapes from the solid lubricant 472 increases, and the amount of lubricant supplied onto the photosensitive drum 41 increases.

  Therefore, in the most upstream yellow image forming portion Y, the set length of the spring 474c is set to be long as shown in FIG. 9A, and in the downstream color image forming portion, the spring is formed as shown in FIG. Set so as to shorten the set length of 474c. By doing this, it is possible to reduce the lubricant supply amount onto the most upstream color photosensitive drum 41 compared to the lubricant supply amount onto the downstream color photosensitive drum 41.

Further, although the case where the contact force of the solid lubricant 472 to the brush roller 471 is changed by changing the set length of the spring 474c has been described above, by using one having a different spring constant or one having a different spring length. Alternatively, the contact force of the solid lubricant 472 with the brush roller 471 can be changed in the most upstream imaging section and the downstream imaging section.
The contact force of the solid lubricant 472 may be changed by a method other than the above.

  As described above, in the image forming apparatus 1 according to the first embodiment, the lubricant supply amount is made different between the imaging unit of the most upstream color and the imaging unit of the downstream color. That is, the amount of lubricant on the photosensitive drum 41 can be controlled within a certain range in all units, even if it is affected by the reverse transfer toner, by making the lubricant amount of the most upstream color smaller than that of the downstream color. And there is no occurrence of quality problems of granular noise, and the life of the cleaning blade can be secured.

  The image forming apparatus 1 according to the first embodiment controls the contact force of the solid lubricant 472 to the photosensitive drum 41 by the set length of the spring 474c. Therefore, the amount of lubricant supplied can be adjusted during the image formation to change the amount of brush roller 471 scraping off the lubricant. Further, even if the lubricant supply amount fluctuates depending on the durability and the environment, the lubricant supply amount can be adjusted within a certain range.

The lubricant supply amount to the photosensitive drum 41 can also be changed by controlling the number of rotations of the brush roller 471.
Specifically, when the rotation number of the brush roller 471 is increased, the width of contact with the photosensitive drum 41 per unit time is increased, and the lubricant supply amount to the photosensitive drum 41 is increased. On the other hand, when the rotational speed of the brush roller 471 is reduced, the amount of lubricant supplied to the photosensitive drum 41 is reduced.
Therefore, in order to make the lubricant amount of the most upstream color less than the downstream color, the number of rotations of the most upstream brush roller 471 may be smaller than that of the downstream color. In order to control the number of revolutions of the brush roller 471, a motor for driving the brush roller 471 may be connected to change the number of revolutions of the motor.
In this case, since a mechanical mechanism for changing the set length of the spring 474c as described above is not necessary, space can be saved.

Further, as described above, the solid lubricant 472 is brought into contact with the brush roller 471 and is not limited to being supplied to the photosensitive drum 41 via the brush roller 471, but the solid lubricant 472 is brought into direct contact with the photosensitive drum 41. Lubricant may be supplied to the photosensitive drum 41. The configuration in this case is shown in FIG.
The solid lubricant 472 is in direct contact with the photosensitive drum 41 at the downstream portion of the cleaning blade 46 in the rotational direction of the photosensitive drum 41. A spring 474c (pressing member) is in contact with the solid lubricant 472 by the holding member 474a, the guide 474b, and the eccentric cam 474d (not shown) as with the contact with the brush roller 471, and the photosensitive drum is driven by the force of the spring 474c. 41 is pressed against. In order to control the amount of lubricant supplied to the photosensitive drum 41, the contact force of the solid lubricant 472 with the photosensitive drum 41 may be controlled. The control mechanism of the contact force of the solid lubricant 472 with respect to the photosensitive drum 41 is the same as that in the case of contact with the brush roller 471, and may be configured as shown in FIG.
In order to change the contact force of the solid lubricant 472 against the photosensitive drum 41, the eccentric cam 474d (not shown) may be rotated and the set length of the spring 474c may be changed. The eccentric cam 474 d may be set so that the length of the spring 474 c is longer.

The lubricant supply amount to the photosensitive drum 41 can also be changed by making the solid lubricant 472 different in hardness.
By changing the hardness of the solid lubricant 472, the amount of lubricant scraped off by the brush roller 471 can be changed, and the amount of lubricant supplied to the photosensitive drum 41 can be controlled. When the hardness of the solid lubricant 472 is increased, the amount of lubricant scraped off by the brush roller 471 decreases, and as a result, the amount of lubricant supplied to the photosensitive drum 41 also decreases. Therefore, in order to make the lubricant supply amount of the most upstream color image forming portion smaller than that of the downstream color, the hardness of the solid lubricant 472 used for the most upstream color may be made higher than the hardness of the solid lubricant 472 used for the downstream color.
Further, as described above, only the hardness of the solid lubricant 472 may be changed, or may be combined with the above-described method.
In this case, the lubricant supply amount can be controlled with a simple configuration as compared with the case where the set length of the spring 474c is controlled as described above, and the effect can be obtained at low cost.

  In the above embodiment, although the lubricant supply amount is set in two steps between the most upstream color image forming unit and the other image forming units, the present invention is not limited to this, and for each image forming unit The lubricant supply amount may be varied according to the order from the upstream side. This makes it possible to control the lubricant supply amount in consideration of the influence of all the imaging units located upstream of the respective imaging units.

Second Embodiment
Next, an image forming apparatus 1 according to the second embodiment will be described.
In the first embodiment, since the lubricant supply amount is made different between the most upstream color image forming unit and the downstream color image forming unit, each image forming unit is configured to reduce the lubricant supply amount in the most upstream color image forming unit. The image forming apparatus 1 according to the second embodiment controls the amount of lubricant supplied in the image forming unit of the downstream color in accordance with the amount of toner on the photosensitive drum 41. .
In addition, about the structure similar to 1st Embodiment, the same code | symbol is attached | subjected and the detailed description is abbreviate | omitted for simplification of description.

<Relationship between transfer voltage and reverse transfer toner amount>
The amount of reverse transfer toner reaching the cleaning blade 46 changes depending on the transfer voltage of the downstream color and the amount of toner (image area ratio) of the upstream color. Therefore, by detecting these and adjusting the lubricant supply amount of the downstream color, it is possible to control the lubricant amount of the downstream color more properly.

Generally, it is known that the higher the transfer voltage, the more the reverse transfer toner.
Reverse transfer toner is considered to occur as follows. When the transfer voltage applied to the transfer roller 452 becomes high, the current flowing to the photosensitive member 41 via the intermediate transfer belt 451 becomes large. When toner is present in the area, the charge of the toner is attenuated, and toner having a reverse polarity to the original polarity is generated. As a result, reverse transfer toner is generated which moves from the intermediate transfer belt 451 to the photosensitive member 41 contrary to the original toner due to the transfer electric field.

  Generally, the surface potential of the photosensitive drum 41 before transfer is about -600 V in the background part and about -50 V in the solid part. The transfer voltage is a voltage that is applied to the transfer roller 452 and is suitable for transferring the toner present on the solid portion on the photosensitive drum 41 onto the intermediate transfer belt 451. For example, when the transfer voltage is applied to the transfer roller 452 so that the surface of the intermediate transfer belt 451 is 500 V as a voltage suitable for transfer, the potential difference between the intermediate transfer belt 451 and the photosensitive drum 41 at the solid portion is 550 V However, in the background portion, a potential difference of 1100 V is generated by the influence of the surface potential of the photosensitive drum 41.

The magenta image forming unit M will be described by way of example with reference to FIG. FIG. 12 is a schematic view of the surface of the photosensitive drum 41 of the magenta image forming unit M. As shown in FIG. When the magenta solid portion Ma is formed as shown in the figure, the outer portion is the magenta background portion Md.
When self-color (here, magenta) toner is transferred to the intermediate transfer belt 451, since self-color toner is present in the magenta solid portion Ma, there is a possibility that magenta reverse transfer toner may be generated due to the potential difference in the magenta background portion Md. Absent.
However, upstream color toner (here, yellow) may be present in the magenta background Md. As shown in the drawing, when the yellow solid portion Ya exists, the potential difference of the intermediate transfer belt 451 in the portion where the magenta background portion Md and the yellow solid portion Ya overlap with each other becomes large. As a result, due to the excess current flowing from the intermediate transfer belt 451 to the photosensitive drum 41, the charge of the yellow toner becomes reverse polarity. As a result, as shown in the figure, a yellow reverse transfer toner Yc which is reversely transferred from the intermediate transfer belt 451 to the photosensitive drum 41 is generated.

The generation rate of the reverse transfer toner can be estimated from the transfer voltage applied to the transfer roller 452. As described above, since the potential difference between the background portion and the surface of the photosensitive drum 41 is large, reverse transfer toner is easily generated. However, when the transfer voltage is increased, reverse transfer toner is generated even in the solid portion.
On the other hand, when the toner of the upstream color is not present on the intermediate transfer belt 451 even if the transfer voltage is high, the reverse transfer toner of the downstream color is not generated.

Therefore, the amount of reverse transfer toner reaching the cleaning blade 46 needs to be estimated from the transfer voltage of the self color and the image area ratio of the upstream color.
Note that since the toner of the most upstream color affects all the colors downstream, the amount of lubricant supplied in the downstream color should be determined based on the transfer voltage of the image forming section of that color and at least the image area ratio of most upstream color. preferable.

  Furthermore, since reverse transfer toner is likely to be generated in the background portion of the downstream color and reverse transfer is unlikely to occur in the solid portion of the self color, lubricant is supplied based on the area ratio of the upstream color and the area ratio of the self color (downstream color) You may decide the amount. Specifically, for example, in the case of the magenta image forming unit M, the area ratio of yellow (yellow solid area Ya in FIG. 12) to the area ratio of magenta (magenta solid area Ma in FIG. 12) are subtracted from the area ratio (yellow in FIG. 12). The lubricant supply amount may be determined based on the yellow reverse transfer toner Yc).

<Control of lubricant supply amount in downstream color imaging unit>
Lubricant supply amount control in the downstream color image forming unit will be described with reference to the flowchart of FIG. The process shown in FIG. 13 is executed by cooperation of the control unit 10 and the program stored in the storage unit 6.

When a job start signal is input (step S1), the control unit 10 determines an image forming condition, and further sets a transfer voltage (step S2).
Here, the transfer voltage applied to the transfer roller 452 may be set to an appropriate value which is obtained by actually changing the transfer voltage at the start of the image forming apparatus 1 or at the start of a job. It may be set to an appropriate value to be obtained from a table created based on conditions and image information and stored in the storage unit 6.
In addition, since the set appropriate value is also recorded in the storage unit 6, the amount of reverse transfer toner can be calculated based on the transfer voltage. The relationship between the transfer voltage and the amount of reverse transfer toner may be recorded as a table in the storage unit 6.

  Next, the control unit 10 calculates an image area ratio of each color (step S3). The image area ratio can be calculated from the image information of each color of the image to be printed.

The control unit 10 obtains an amount of reverse transfer toner from the transfer voltage and the image area ratio obtained in steps S2 and S3 (step S4).
Here, as described above, in the case of the magenta image forming unit M, the area ratio of yellow (yellow solid area Ya in FIG. 12) is subtracted from the area ratio of magenta (magenta solid area Ma in FIG. 12), and the difference (FIG. 12) The amount of reverse transfer toner is calculated based on the yellow reverse transfer toner Yc) in the above.

Next, on the basis of the reverse transfer toner amount determined in step S4, the control unit 10 determines the lubricant supply amount to be adjusted (step 5).
The relationship between the reverse transfer toner amount and the lubricant supply amount is recorded in the storage unit 6 as a table.

Based on the lubricant supply amount to be adjusted, the control unit 10 controls the contact force of the solid lubricant 472 to the brush roller 471 to make the supply amount (step S6). In the present embodiment, as in the first embodiment, the contact force of the solid lubricant 472 to the brush roller 471 is controlled by changing the set length of the spring 474c. The relationship between the lubricant supply amount and the spring 474c is recorded in the storage unit 6 as a table.
Besides the above, it is also possible to control the lubricant supply amount by the method as shown in the first embodiment.

  After the lubricant supply amount is set as described above, the control unit 10 starts printing (step S7), and ends the lubricant supply amount control.

  As described above, the image forming apparatus 1 according to the second embodiment calculates the amount of reverse transfer toner, and controls the amount of lubricant supplied to the downstream photosensitive drum 41 based on the result. Therefore, since the lubricant supply amount of the downstream color can be controlled according to the reverse transfer toner amount reaching the cleaning blade 46, the lubricant fluctuation range on the photosensitive drum 41 can be reduced.

The transfer voltage may be controlled as above using the transfer voltage of each color, but the image area ratio is affected by the image forming unit upstream by controlling the order of the image forming unit with respect to the rotation direction of the intermediate transfer belt 451. Need to be considered. Only the yellow toner affects the magenta image forming unit M, which is the image forming unit of the second color from the upstream side, but the yellow toner and magenta toner for the cyan image forming unit C, and the yellow toner and magenta toner for the black image forming unit K Affected by toner and cyan toner.
Therefore, in order to control the amount of lubricant on the photosensitive drum 41 more accurately, it is preferable to obtain the amount of reverse transfer toner based on the image area ratio of all colors upstream of the self color unit.
On the other hand, since the most upstream yellow toner affects all the downstream imaging units, at least the most upstream image area ratio needs to be considered in the downstream nucleation section.

In the present embodiment, the amount of reverse transfer toner reaching the cleaning blade 46 is estimated from the set transfer voltage. However, it is also possible to actually measure the amount of reverse transfer toner.
The amount of reverse transfer toner can be measured on the photosensitive drum 41 or on the intermediate transfer belt 451 using an optical density sensor. The case of measuring the amount of toner on the intermediate transfer belt 451 will be described. As shown in FIG. 14, density sensors SE1 and SE2 (measuring section) are provided to measure the amount of toner on the intermediate transfer belt 451 before and after entering the nip with the photosensitive drum 41. When reverse transfer toner is generated, the toner amount on the intermediate transfer belt 451 is reduced by passing through the nip portion with the photosensitive drum 41. That is, the amount of toner detected by the density sensor SE2 disposed downstream of the intermediate transfer belt 451 is smaller than the amount of toner detected by the concentration sensor SE1 disposed upstream of the intermediate transfer belt 451. Therefore, the amount of reverse transfer toner can be determined by calculating the difference between the toner amounts detected by the density sensors SE1 and SE2.
The amount of reverse transfer toner can be determined from the output values of the upstream color toner density sensors SE1 and SE2 when a patch image of the upstream color is formed between the print image and the image of the print image and the own color is the background. It can. Also in this case, the amount of reverse transfer toner reaching the cleaning blade 46 changes depending on the image area ratio of the upstream color, so it is necessary to determine the lubricant amount to be adjusted taking into consideration the image area ratio.

[Other embodiments]
As mentioned above, although it concretely explained based on the embodiment concerning the present invention, the above-mentioned embodiment is a suitable example of the present invention, and is not limited to this.

For example, although the case where the lubricant application mechanism 47 is provided on the upstream side of the cleaning blade 46 has been described, it may be provided on the downstream side of the cleaning blade 46 as shown in FIG.
Specifically, the collection roller 473 provided in FIG. 3 is not necessary, and a flat leveling blade 475 made of an elastic body for leveling the lubricant supplied onto the photosensitive drum 41 is provided.
Also in this configuration, the lubricant on the photosensitive drum 41 is recovered by the cleaning blade 46, and the mechanism of the recovery amount being influenced by the reverse transfer toner is the same, and the lubricant amount on the photosensitive drum 41 of each color is in a certain range In order to achieve the above control, it is necessary to supply the most upstream color lubricant less than the downstream color.
The control of the lubricant supply amount is the same as in the case where the brush roller 471 is provided on the upstream side of the cleaning blade 46.

Alternatively, as shown in FIG. 16, lubricant particles may be supplied to the photosensitive drum 41 together with the toner by the developing device 44 using a developer obtained by externally adding lubricant particles to the toner.
Since the lubricant is supplied to the photosensitive drum 41 by the toner, the brush roller 471, the solid lubricant 472 and the collection roller 473 are eliminated from the system of FIG.
In the toner external addition method, the lubricant on the photosensitive drum 41 is recovered by the cleaning blade 46, and the mechanism by which the recovery amount is affected by the reverse transfer toner is the same, and the lubricant amount on the photosensitive drum 41 of each color is in a certain range In order to achieve the above control, it is necessary to supply the most upstream color lubricant less than the downstream color. Therefore, it is necessary to make the amount of lubricant contained in the most upstream toner smaller than that of the downstream color.
In the toner external addition method, a brush roller 471 and a collection roller 473 may be provided upstream of the cleaning blade 46.

  In addition, the detailed configuration of each device constituting the image forming device and the detailed operation of each device can be appropriately changed without departing from the scope of the present invention.

1 image forming apparatus 4 image forming unit 41 photosensitive drum (image carrier)
42 charging device 43 exposure device 44 developing device 45 transfer device 451 intermediate transfer belt (intermediate transfer member)
452 transfer roller 46 cleaning blade (cleaning member)
47 Lubricant application mechanism (lubricant supply device)
471 Brush roller (rotary member)
472 Solid lubricant 473 Recovery roller 474a Holding member 474b Guide 474c Spring (pressing member)
474d Eccentric cam 10 Control unit Y Yellow image formation unit (image formation device)
M magenta imaging unit (imaging device)
C Cyan imaging unit (imaging device)
K Black Imager (Imager)
SE1, SE2 concentration sensor (measurement unit)

Claims (12)

An intermediate transfer member for transferring a toner image to paper;
A plurality of imaging devices disposed along the rotational direction of the intermediate transfer member,
The imaging device
An image carrier that carries a toner image to be transferred to a sheet;
A charging device for charging the image carrier;
A developing device that supplies toner to the image carrier and develops a toner image;
And a cleaning member disposed downstream of the transfer position with the intermediate transfer member and upstream of the charging device in the rotational direction of the image carrier and cleaning the surface by coming into contact with the image carrier.
A lubricant having a polarity opposite to that of the toner supplied by the developing device is supplied to the image carrier.
The lubricant supply amount to the image carrier of one imaging device disposed on the most upstream side in the rotational direction of the intermediate transfer member is smaller than the lubricant supply amount to the image carrier of the other imaging device. An image forming apparatus characterized by A lubricant supply device disposed downstream of the transfer position with the intermediate transfer member in the rotation direction of the image carrier and supplying the lubricant to the image carrier;
A controller for controlling the lubricant supply amount in the lubricant supply device;
The lubricant supply device
A solid lubricant, and a rotating member that rotates in contact with the image carrier and the solid lubricant;
The control unit
The contact force of the solid lubricant to the rotary member in the lubricant supply device of the one imaging device is controlled to be weaker than the contact force of the solid lubricant to the rotary member in the lubricant supply device of another imaging device An image forming apparatus according to claim 1. A lubricant supply device disposed downstream of the transfer position with the intermediate transfer member in the rotation direction of the image carrier and supplying the lubricant to the image carrier;
A controller for controlling the lubricant supply amount in the lubricant supply device;
The lubricant supply device
A solid lubricant, and a rotating member that rotates in contact with the image carrier and the solid lubricant;
The control unit
The rotation number of the rotating member in the lubricant supplying device of the one imaging device is controlled to be smaller than the rotation number of the rotating member in the lubricant supplying device of the other imaging device. The image forming apparatus according to 1 or 2. A lubricant supply device disposed downstream of the transfer position with the intermediate transfer member in the rotation direction of the image carrier and supplying the lubricant to the image carrier;
A controller for controlling the lubricant supply amount in the lubricant supply device;
The lubricant supply device
A solid lubricant, and a pressing member for pressing the solid lubricant against the image carrier;
The control unit
The pressing force of the pressing member in the lubricant supplying device of the one imaging device is controlled to be smaller than the pressing force of the pressing member in the lubricant supplying device of the other imaging device. The image forming apparatus according to 1. The control unit
The lubricant supply amount in the lubricant supplying device of the other imaging device is controlled based on the transfer voltage in the imaging device and the image area ratio of the toner image formed by at least the one imaging device. The image forming apparatus according to any one of claims 2 to 4, characterized in that: The imaging device
A measurement unit configured to measure an amount of toner transferred from the intermediate transfer body to the image carrier;
The control unit
The lubricant supply amount in the lubricant supplying device of the other imaging device, the toner amount measured by the measuring unit in the imaging device, and the image area ratio of the toner image formed in at least one of the one imaging device The image forming apparatus according to any one of claims 2 to 5, wherein control is performed based on and. The control unit controls the lubricant supply device of the image forming apparatus disposed upstream in the rotational direction of the intermediate transfer member so as to reduce the lubricant supply amount. An image forming apparatus according to claim 1. The lubricant supply device comprises a solid lubricant,
The hardness of the said solid lubricant in the lubricant supply apparatus of the said 1 imaging device is higher than the hardness of the said solid lubricant in the lubricant supply apparatus of another imaging device, It is characterized by the above-mentioned. An image forming apparatus according to claim 1. The image forming apparatus according to claim 8, wherein the solid lubricant has a higher hardness as a lubricant supplying device of an imaging device disposed upstream in the rotational direction of the intermediate transfer member. The developing device supplies a toner to which a lubricant is added to the image bearing member,
The amount of lubricant added to the toner in one imaging device disposed on the most upstream side in the rotational direction of the intermediate transfer member is smaller than the amount of lubricant added to the toner in the other imaging device. An image forming apparatus according to claim 1. The image forming apparatus according to claim 10, wherein the amount of the lubricant added to the toner is smaller as the image forming apparatus is disposed more upstream in the rotational direction of the intermediate transfer member. An intermediate transfer body for transferring a toner image onto a sheet of paper, and a plurality of image forming devices arranged along the rotational direction of the intermediate transfer body, the image forming device carrying a toner image to be transferred onto a sheet of paper An image carrier, a charging device for charging the image carrier, a developing device for supplying a toner to the image carrier and developing a toner image, and a transfer with the intermediate transfer member in the rotation direction of the image carrier A cleaning member disposed downstream of the position and upstream of the charging device and in contact with the image carrier to clean the surface, and downstream of the transfer position with the intermediate transfer member in the rotational direction of the image carrier And b) a lubricant supply device arranged to supply a lubricant to the image carrier.
The lubricant supply amount in the lubricant supplying device of one imaging device disposed on the most upstream side in the rotational direction of the intermediate transfer member is controlled to be smaller than the lubricant supplying amount in the lubricant supplying device of the other imaging device. A program to function as a controller.

Images