JP2004258324A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To compact and eliminate residual liquid developer on a photoreceptor drum well in an image forming apparatus using the liquid developer. <P>SOLUTION: An electrifying roll 34a is installed in contact with the photoreceptor drum 31a and after a toner image is transferred to a body to be transferred, the thickness of the layer of the residual liquid developer remaining on the image carrier is restricted to be 30μm or less. The photoreceptor drum is electrified by the electrifying roll 34a and afterward the remaining residual liquid developer on the photoreceptor is eliminated. A cleaning member 37a is installed in contact with the electrifying roll and the attached residual developer is eliminated by the cleaning member. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus for developing an electrostatic latent image formed on an image carrier such as a photosensitive drum using a liquid developer containing a toner in a liquid carrier (solvent) to obtain an image, and in particular, to an image forming apparatus. The present invention relates to an image forming apparatus including a mechanism for cleaning and collecting a liquid developer remaining on an image carrier.
[0002]
[Prior art]
Generally, in an image forming apparatus (hereinafter, referred to as a wet image forming apparatus) that forms an image using a liquid developer containing a toner in a liquid carrier (so-called liquid toner), offset printing can be performed by using fine toner. In addition to realizing high image quality, a sufficient image density can be obtained even if the amount of toner is small, so that there is an advantage that it is economical.
[0003]
Also in a wet image forming apparatus, in a printing process (image forming process), charging of a photosensitive drum as an image carrier, exposure of a photosensitive drum (formation of an electrostatic latent image), development, transfer, photosensitive drum ( The process is performed in the order of cleaning of the image carrier) and charging of the photosensitive drum. In the cleaning step, the liquid developer remaining on the photosensitive drum is removed to prevent image defects in the next developing process. That is, if the cleaning is insufficient, in the next image forming process, poor charging and poor exposure occur due to the residual liquid developer, thereby causing image defects.
[0004]
The cleaning device used in the wet image forming apparatus includes a cleaning foam roller and a cleaning blade, and a cleaning blade thinner than the cleaning blade is disposed downstream of the cleaning foam roller between the cleaning foam roller and the cleaning blade. There is one in which the developer of the photoreceptor is scraped by the scraping blade (see Patent Document 1).
[0005]
In addition, there is a configuration in which a rotatable roll member is provided in contact with the photoconductor drum, and this roll member is used as an elastic roll, and a bias voltage is applied to the roll member to clean the photoconductor drum (Japanese Patent Application Laid-Open No. H10-163873). reference).
[0006]
Further, in a so-called dry-type image forming apparatus, a charging roller is used as a charging unit, and a cleaning member for cleaning the charging roller is configured by an elastic roller, and a forward feed rotation is performed at a contact position between the cleaning member and the charging roller. In this direction, the cleaning member is driven to rotate so that the peripheral speed of the cleaning member is greater than the peripheral speed of the charging roller at this contact position, so that the cleaning of the charging roller is stably performed over a long period of time. (See Patent Document 3).
[0007]
Similarly, there is a dry-type image forming apparatus in which a charging roller is used as a charging unit and toner adhered to the charging roller is cleaned by a cleaning member (Patent Document 4).
[0008]
[Patent Document 1]
JP-A-6-230704 (paragraphs (0009) to (0015), FIG. 1)
[Patent Document 2]
JP-A-8-254932 (paragraphs (0032) to (0039), FIG. 1)
[Patent Document 3]
JP-A-8-227208 (paragraphs (0027) to (0031), FIG. 1)
[Patent Document 4]
JP-A-2000-258978 (paragraphs (0033) to (0036), FIGS. 2 to 5)
[0009]
[Problems to be solved by the invention]
By the way, in a conventional wet image forming apparatus, the amount of liquid developer (particularly, liquid carrier) remaining on the photosensitive drum after transferring a toner image from the photosensitive drum is large. Although the cleaning device described in (1) includes a cleaning foam roller, a cleaning blade, and a scraping blade to sufficiently remove the liquid developer remaining on the photoconductor drum, the cleaning device does not include the cleaning foam roller. Since the cleaning device and the cleaning blade are provided, there is a problem that the cleaning device itself becomes large.
[0010]
Further, in the cleaning device described in Patent Document 2, when the photosensitive drum is cleaned, a bias voltage is applied to the elastic roll by using the elastic roll, so that the cleaning device itself similarly increases in size. Therefore, there is a problem that the size of the image forming apparatus itself increases.
[0011]
Patent Documents 3 and 4 only describe that in a dry-type image forming apparatus using a charging roller as a charging unit, a cleaning member for cleaning the charging roller is provided, and the charging roller is cleaned by the cleaning member. In a wet-type image forming apparatus, it is necessary to provide a separate cleaning device in order to remove the liquid developer remaining on the photosensitive drum.
[0012]
In any case, in the wet image forming apparatus, when cleaning the liquid developer remaining on the photosensitive drum, the cleaning apparatus is enlarged as described above, and as a result, the image forming apparatus is made compact. There is a problem that cannot be done.
[0013]
In the wet image forming apparatus, the liquid developer removed from the photosensitive drum by the cleaning device is collected in a developer tank and used again for development. Conventionally, in a wet image forming apparatus, a cleaning device that cleans a photoconductor drum is disposed downstream of a transfer device (for example, a transfer roller) in the rotation direction of the photoconductor drum and upstream of a charger (that is, After the toner image on the photoconductive drum is transferred to the recording paper, the liquid developer remaining on the photoconductive drum is charged before the photoconductive drum is charged. They are removed and collected.
[0014]
However, when a cleaning device is disposed between the charging device and the transfer roller, the position of the cleaning device and the developing device (developing device) must be inevitably separated (that is, the developing device). After the development, the transfer is performed, and then the cleaning is performed.Therefore, since a transfer device such as a transfer roller exists between the developing device and the cleaning device, the cleaning device and the developing device are separated from each other. ).
[0015]
Therefore, when returning the liquid developer that has been cleaned and collected by the cleaning device to the liquid developer tank, considering that the liquid developer tank is disposed near the developing device, the liquid developer tank can be moved from the cleaning device to the developer tank. However, there is a problem that the wet image forming apparatus itself becomes large in size.
[0016]
Furthermore, if the pipe for collecting the liquid developer becomes long, a large number of joints will inevitably occur in the pipe, and the joints of the pipes must be sealed to prevent leakage of the liquid developer. There is also a problem that must be done.
[0017]
SUMMARY OF THE INVENTION An object of the present invention is to provide a wet image forming apparatus which is compact and can remove liquid developer remaining on an image carrier such as a photosensitive drum satisfactorily.
[0018]
[Means for Solving the Problems]
According to the present invention, an image carrier that rotates in a predetermined direction, a charging unit that charges the image carrier, an exposure unit that forms an electrostatic latent image on the image carrier, and at least an insulating liquid carrier An image forming apparatus, comprising: developing means for developing the electrostatic latent image with a liquid developer comprising a toner and a toner to form a toner image, and transferring the toner image to a transfer target to form an image. The charging unit charges the image carrier by contacting the image carrier, transfers the toner image to the transfer target body, and removes a residual liquid developer remaining on the image carrier. An image forming apparatus that has a function of removing the toner, and the charging unit includes a cleaning member that contacts the charging unit and removes the residual liquid developer attached to the charging unit. can get. Then, after transferring the toner image to the transfer target, the layer thickness of the residual liquid developer remaining on the image carrier is regulated to 30 μm or less.
[0019]
In this way, the charging means (charging roller) comes into contact with the image carrier (photosensitive drum) to charge the image carrier and transfer the toner image to the transfer-receiving body, and then remains on the image carrier. The residual liquid developer is removed, and the residual liquid developer adhering to the charging means is removed by a cleaning member. At this time, the residual liquid developer remaining on the image carrier after transferring the toner image to the transfer-receiving member If the layer thickness is regulated to 30 μm or less, the liquid developer remaining on the image carrier can be removed satisfactorily by the charging means, and the image forming apparatus itself can be made compact without requiring a separate cleaning device. .
[0020]
For example, the developing unit includes a developer tank in which the liquid developer is stored, a developing roller that develops the electrostatic latent image with the liquid developer, and a layer that supplies the liquid developer to the developing roller and forms the layer. A roller member that regulates the thickness of the liquid developer on the roller member such that the layer thickness of the residual liquid developer on the image carrier is 30 μm or less. The restricting means is provided, for example, close to or in contact with the roller member.
[0021]
In this way, the thickness of the liquid developer on the roller member (anilox roller) provided in the developing means is regulated by the regulating means (regulating blade, for example, an anilox blade), and the residual liquid remaining on the image carrier is regulated. Since the layer thickness of the liquid developer supplied to the developing roller is regulated so that the layer thickness of the developer is 30 μm or less, the layer thickness of the residual liquid developer can be easily regulated.
[0022]
Further, in the present invention, the charging unit and the cleaning member are positioned above a bottom surface of the developer tank so as to face a space defining the developer tank. Further, when the rotation center axis of the image carrier is the origin of the two-dimensional coordinates, the charging unit and the cleaning member are positioned in a third quadrant of the two-dimensional coordinates, and the developing roller is moved to a third quadrant of the two-dimensional coordinates. The contact portion between the charging unit and the image carrier and the contact portion between the charging unit and the cleaning member may face a space defining the developer tank. The developer tank may be positioned above the bottom surface.
[0023]
With this configuration, the residual liquid developer collected by the charging unit and the cleaning member can be guided to the developer tank without requiring a pipe or the like.
[0024]
Further, in the present invention, the cleaning member collects the residual liquid developer adhered to the charging unit and guides the residual liquid developer to the developer tank at a position avoiding the developing roller. The roller member is disposed so as to be able to be disposed.
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be illustratively described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention to them unless otherwise specified, and are merely mere descriptions. This is just an example.
[0026]
Referring to FIG. 1, the illustrated wet image forming apparatus is a so-called tandem type image forming apparatus, and includes an endless belt-shaped intermediate transfer belt 11 as an intermediate transfer body. A plurality of image forming units are arranged along the rotation direction of the intermediate transfer belt 11 (conveying direction: indicated by solid arrows in the drawing). In the illustrated example, four image forming units 21 to 24 are arranged along the intermediate transfer belt 11. For example, from the right side in the drawing, a yellow (Y) image forming unit and a magenta (M) image forming unit , A cyan (C) image forming unit, and a black (B) image forming unit.
[0027]
The image forming units 21 to 24 are provided with photoconductor drums 31a to 31d, developing devices 32a to 32d, exposing units 33a to 33d, charging rollers 34a to 34d used as charging units, and power reduction units 35a to 35d, respectively. The developing devices 32a to 32d develop the electrostatic latent images formed on the photosensitive drums 31a to 31d with the respective color toners using a liquid developer in which a liquid carrier (solvent) contains a toner or the like. Note that cleaning members (cleaning blades) 37a to 37d are in contact with the charging rollers 34a to 34d, respectively.
[0028]
The configuration of each of the developing devices 32a to 32d will be described. The developing devices 32a to 32d include developer tanks 41a to 41d storing liquid developer, developer supply rollers 42a to 42d, anilox rollers 43a to 43d, and developing rollers 44a to 44d. Then, as shown, the developer supply roller 42a supplies the liquid developer in the developer tank 41a to the anilox roller 43a, and the layer thickness of the liquid developer is regulated by the anilox roller 43a. The liquid developer is supplied to the developing roller 44a from the anilox roller 43a, and the developing roller 44a comes into contact with the photosensitive drum 31a to develop the electrostatic latent image formed on the photosensitive drum 31a with the liquid developer. Form a toner image.
[0029]
The developing devices 32a to 32d have the same configuration as the developing device 32a, and the developing devices 32b to 32d form toner images on the photosensitive drums 31b to 31d with liquid developers, respectively.
[0030]
Paying attention to the image forming unit 21, a developing roller 44a is disposed downstream of the charging roller 34a along the rotation direction of the photosensitive drum 31a (indicated by a broken line arrow in FIG. 1). 34a is located immediately above the developer tank 41a, and similarly, one end of the cleaning blade 37a (an end opposite to the end in contact with the charging roller 34a) is located immediately above the developer tank 41a. positioned. Then, as described later, the liquid developer removed from the charging roller 34a by the cleaning member 37a immediately falls into the developer tank 41a.
[0031]
Primary transfer rollers 51 to 54 are arranged to face the photoconductor drums 31a to 31d, and the intermediate transfer belt 11 is sandwiched between the photoconductor drums 31a to 31d and the primary transfer rollers 51 to 54. As shown in the figure, the intermediate transfer belt 11 is supported by a driving roller 55 and a support roller 56 and is conveyed in the direction of the solid line arrow in the drawing. A secondary transfer roller 57 is provided.
[0032]
Then, the intermediate transfer belt 11 is held between the support roller 56 and the secondary transfer roller 57. A sheet 61 (not shown in FIG. 1) is provided between the secondary transfer roller 57 and the intermediate transfer belt 11 (nip portion) from a sheet feeding device (not shown) via a registration roller (not shown). Supplied.
[0033]
During image formation, the surface of the photosensitive drum 31a is uniformly charged by the charging roller 34a, and then the photosensitive drum 31a is exposed to form an electrostatic latent image on the surface of the photosensitive drum 31a. Thereafter, the electrostatic latent image is developed to form a toner image on the photosensitive drum 31a. The toner image on the photosensitive drum 31a is transferred to the intermediate transfer belt 11 by the primary transfer roller 51.
[0034]
Also on the photoconductor drums 31b to 31d, toner images are formed in the same manner as the photoconductor drum 31a, and the toner images formed on the photoconductor drums 31b to 31d are sequentially transferred onto the intermediate transfer belt 11 by the primary transfer rollers 52 to 54. Is transferred to That is, in each of the image forming units 21 to 24, the toner image is transferred to the intermediate transfer belt 11 as a primary transfer image. In this way, for example, cyan, magenta, yellow, and black toner images are sequentially superimposed on the intermediate transfer belt 11 and transferred.
[0035]
As described above, the toner image (primary transfer image) transferred to the intermediate transfer belt 11 is sent toward the secondary transfer roller 57 as the intermediate transfer belt 11 is conveyed. Then, the toner image (primary transfer image) on the intermediate transfer belt 11 is transferred to the sheet by the secondary transfer roller 57 (secondary transfer). A fixing unit (fixing roller pair) 62 is disposed downstream in the sheet conveyance direction, and the secondary transfer image transferred to the sheet is pressed and heated by the fixing unit 62 to be fixed.
[0036]
Although not shown, the residual toner remaining on the intermediate transfer belt 11 is cleaned by a cleaning blade.
[0037]
Here, paying attention to the image forming unit 21 with reference to FIG. 2, FIG. 2 is a configuration diagram showing the image forming unit 21 in detail, and as described with reference to FIG. The charging roller 34a, the exposure device 33a, and the developing roller 44a are arranged in this order along the rotation direction of the photosensitive drum 31a, and the photosensitive drum 31a is an intermediate transfer member (intermediate transfer belt) downstream of the developing roller 44a. 11 is in contact.
[0038]
As shown, one end (tip) of the cleaning blade 37a is in contact with the surface of the charging roller 34a (the cleaning blade 37a is in contact with the tangent drawn from the contact with respect to the rotation direction of the charging roller 34a). (It is arranged so that the angle formed with the surface of the photosensitive drum becomes an acute angle.) As described above, the rear end of the cleaning blade 37a is located in the developer tank 41a.
[0039]
As described with reference to FIG. 1, the electrostatic latent image formed on the photosensitive drum 31a is developed by the developing roller 44a to become a toner image. That is, the electrostatic latent image is developed with the liquid developer to form a toner image on the photosensitive drum 31a (at the downstream side of the developing roller 44a, the liquid developer (toner + solvent) is applied to the photosensitive drum 31a. ) Is attached). The toner image on the photosensitive drum 31a is transferred to the intermediate transfer belt 11 by a bias voltage applied to the photosensitive drum 31a by the primary transfer roller 52.
[0040]
After the transfer of the toner image to the intermediate transfer belt 11, almost only the solvent (liquid carrier) remains on the photosensitive drum 31a. Thereafter, the photosensitive drum 31a is gradually charged by the voltage reducer 35a. The surface of the photosensitive drum 31a is uniformly charged while the liquid developer remaining on the photosensitive drum 31a is removed by the charging roller 34a, and the photosensitive drum 31a is exposed by the exposure device 33a. An electrostatic latent image is formed again.
[0041]
As described above, the residual liquid developer on the photosensitive drum 31a is removed by the charging roller 34a, but the liquid developer attached to the charging roller 34a is removed by the cleaning blade 37a, and the collected developer is removed. And falls down to the developer tank 41a through the cleaning blade 37a.
[0042]
As described above, the photosensitive drum 31a is charged while the residual liquid developer on the photosensitive drum 31a is removed by the charging roller 34a. Therefore, the residual liquid toner on the photosensitive drum 31a is separately removed. There is no need to provide a cleaning device for cleaning the member, that is, the photosensitive drum 31a. In addition, the liquid developer adhering to the charging roller 34a is cleaned by the cleaning blade 37a and collected in the developer tank 41a, so that a pipe or the like for returning the liquid developer to the developer tank becomes unnecessary. .
[0043]
As shown in FIG. 2, a layer thickness regulating member (anilox blade) 45a is disposed in contact with or near the anilox roller 43a, and the anilox blade 45a reduces the layer thickness of the liquid developer on the anilox roller. Be regulated. A developing roller blade 46a is disposed on the developing roller 44a, and the developing roller 44a is cleaned by the developing roller blade 46a during non-image formation. Further, the other image forming units 22 to 24 are configured similarly to the image forming unit 21.
[0044]
Under the following conditions, an image was formed using the image forming apparatus shown in FIG. In the image forming unit 21, an insulating solvent (for example, a non-volatile solvent such as silicone oil or liquid paraffin, electric resistance: 10 ¹² Ω or more) is used as a solvent, and a black toner having an average particle diameter of 2 μm is used. The toner was contained in an insulating solvent at a concentration (% by weight) of 15% to 20% to obtain a liquid developer. The surface material of the photoconductor drum 31a is, for example, an a-Si photoconductor, the drum diameter is φ80, the surface potential is 400V, and the peripheral speed is 178 mm / s.
[0045]
Further, the anilox roller 43 is made of SUS (or aluminum), and has a helical pattern groove (for example, 200 lines / inch, a depth of 50 μm, an angle of about 45 ° (a V-shaped cross section and a V-shaped Is 45 °), the outer diameter is φ20, and the peripheral speed is 178 mm / s. The developing roller 44 is made of urethane rubber, and has a hardness of 45 degrees in scale A, a surface roughness of Ra = 0.6, a volume resistance of 10 ⁵ to 10 ⁷ Ω · cm, an outer diameter of φ20, and a peripheral speed of 178 mm / s, the developing bias voltage was 250 V, and the material of the developer supply roller 42 was urethane foam, hardness: scale A 25 degrees, outer diameter φ20, and peripheral speed 200 mm / s.
[0046]
On the other hand, the charging roller 34a is made of NBR, has a hardness of 70 degrees A, a volume resistance of 10 ⁹ Ω · cm, an outer diameter of φ10, a peripheral speed of 300 mm / s, and a charging bias of 500 V. The cleaning blade (for the charging roller) 37a is made of urethane, and has a thickness t = 2.0 mm, an angle (an angle formed with the surface in the rotation direction of the charging roller 34a) = 25.9 degrees, and presses the charging roller 34a. Pressure = 2.55 g / mm.
[0047]
The material of the anilox blade 45a is SUS, and the thickness is 0.15 mm. Further, it is in contact with the anilox roller such that the contact angle becomes an acute angle at an angle of 20 degrees. The material of the developing roller blade 46a is urethane, the thickness is 2.0 mm, the angle (the angle between the developing roller 44a and the surface in the rotation direction) = 22.9 degrees, and the pressure for pressing the developing roller 44a is 2. 0 g / mm. The image forming units 22 to 24 have the same configuration.
[0048]
The material of the intermediate transfer belt 11 was epichlorohydrin, the electrical resistance was 10 ⁸ Ω · cm, and the peripheral speed was 178 mm / s. The secondary transfer roller 57 is made of EPDM and has an electric resistance of 10 ⁵ to 10 ⁷ Ω · cm, a peripheral speed of 178 mm / s, and an outer diameter of φ15.
[0049]
When an image was formed under the above-described conditions (here, attention is paid to the image forming unit 21), the liquid developer was pumped up by the developer supply roller 42a, and the liquid developer was formed by the pattern formed on the anilox roller 43a. It was found that the layer thickness of the agent was regulated to about 20 μm. Then, the liquid developer is supplied from the anilox roller 43a to the developing roller 44a, and the electrostatic latent image on the photosensitive drum 31a is developed by the developing roller 44a. The layer thickness depends on the layer thickness of the liquid developer on the anilox roller 43a.
[0050]
The layer thickness of the residual liquid developer on the photosensitive drum 31a after the secondary transfer was measured was about 10 μm. Thereafter, the residual liquid developer on the photosensitive drum 31a is scraped off (to be removed) by the charging roller 34a, but if the layer thickness of the residual liquid developer is about 10 μm, the photosensitive drum It was found that the residual liquid developer on 31a could be removed well.
[0051]
Then, as described above, it was confirmed that the liquid developer adhering to the charging roller 34a was removed by the cleaning blade 37a and collected in the developer tank 41a.
[0052]
Since the solvent (liquid carrier) in the above-described liquid developer is an insulator, it does not affect the charge removal and charging processes. The liquid developer stored in the contact portion between the charging roller 34a and the photosensitive drum 31a and the liquid developer stored in the contact portion between the charging roller 34a and the cleaning blade 37a are removed after stopping the image forming apparatus. It was confirmed that the particles were transmitted to the cleaning blade 37a by the action of gravity and dropped into the developer tank 41a.
[0053]
An image was formed in the same manner by changing the pattern formed on the anilox roller 43a and changing the thickness of the liquid developer layer on the anilox roller 43a. After the secondary transfer, the image remained on the photosensitive drum 31a. It was found that when the layer thickness of the liquid developer to be applied was 30 μm or less, the residual liquid developer on the photosensitive drum 31a could be satisfactorily removed by the charging roller 34a. Also, there is no adverse effect on static elimination and charging.
[0054]
The layer thickness of the liquid developer remaining on the photosensitive drum 31a after the secondary transfer has a correlation with the layer thickness of the liquid developer on the anilox roller 43a.
[0055]
As is clear from the above description, the pattern formed on the anilox roller 43a and the anilox blade 45a function as a regulating means for controlling the layer thickness of the residual liquid developer after transfer to 30 μm or less.
[0056]
Further, as is apparent from the above description and FIG. 2, the charging roller 34a and the cleaning member 37a are positioned above the bottom surface of the developer tank 41a, facing the space defining the developer tank 41a. Become. The contact portion between the charging roller 34a and the photosensitive drum 31a and the contact portion between the charging roller 34a and the cleaning member 37a face the space defining the developer tank 41a, and extend from the bottom of the developer tank 41a. Is also positioned on the upper side.
[0057]
That is, when the rotation center axis of the photosensitive drum 31a is the origin of the two-dimensional coordinates, the charging roller 34a and the cleaning member 37a are positioned in the third quadrant of the two-dimensional coordinates, and the developing roller 44a is positioned in the fourth quadrant of the two-dimensional coordinates. The cleaning member 37a collects the residual liquid developer adhering to the charging roller 34a and guides it to the developer tank 41a at a position avoiding the developing roller 44a.
[0058]
In the example shown in FIG. 1, a color image forming apparatus has been described. However, the present invention can be similarly applied to a monochrome image forming apparatus, and in any case, an image forming apparatus that performs development using a liquid developer. The present invention can be applied to: Further, in the above-described example, the example in which the transfer object is the intermediate transfer belt has been described, but the transfer object may be a recording medium such as a sheet.
[0059]
【The invention's effect】
As described above, according to the present invention, after the charging means (charging roller) comes into contact with the image carrier (photosensitive drum) to charge the image carrier and transfer the toner image to the transfer object, The residual liquid developer remaining on the image carrier is removed, and the residual liquid developer attached to the charging means is removed by a cleaning member. At this time, after the toner image is transferred to the transfer receiving member, Since the layer thickness of the residual liquid developer remaining on the carrier is restricted to 30 μm or less, the liquid developer remaining on the image carrier can be satisfactorily removed by the charging means, and a separate cleaning device is required. Therefore, there is an effect that the image forming apparatus itself can be made compact.
[0060]
In the present invention, the layer thickness of the liquid developer on the roller member (anilox roller) provided in the developing means is regulated so that the layer thickness of the residual liquid developer remaining on the image carrier is 30 μm or less. Since the layer thickness of the liquid developer supplied to the developing roller is regulated, there is an effect that the layer thickness of the residual liquid developer can be easily regulated.
[0061]
Further, in the present invention, since the charging means and the cleaning member face the space defining the developer tank and are positioned above the bottom surface of the developer tank, the residual liquid developed by the charging means and the cleaning member is removed. There is an effect that the developer can be easily guided to the developer tank.
[0062]
Further, in the present invention, when the cleaning member recovers the residual liquid developer attached to the charging unit, the cleaning member guides the liquid developer to the developer tank at a position avoiding the developing roller. The collected liquid developer does not touch, and the layer thickness of the liquid developer on the developing roller is not disturbed.
[Brief description of the drawings]
FIG. 1 is a schematic diagram illustrating an example of an image forming apparatus according to the present invention.
FIG. 2 is a configuration diagram showing the image forming unit shown in FIG. 1 in an enlarged manner in detail.
[Explanation of symbols]
21-24 Image forming units 31a-31d Photoconductor drums 34a-34d Charging rollers 37a-37d Cleaning members 41a-41d Developer tanks 42a-42d Developer supply rollers 43a-43d Anilox rollers 44a-44d Developing rollers

Claims (8)

An image carrier that rotates in a predetermined direction, a charging unit that charges the image carrier, an exposure unit that forms an electrostatic latent image on the image carrier, and a liquid including at least an insulating liquid carrier and a toner An image forming apparatus comprising: developing means for developing the electrostatic latent image with a developer to form a toner image, and performing image formation by transferring the toner image to a transfer target body,
The charging unit has a function of charging the image carrier by contacting the image carrier, transferring the toner image to the transfer target body, and removing a residual liquid developer remaining on the image carrier. An image forming apparatus, wherein the charging unit includes a cleaning member that contacts the charging unit and removes the residual liquid developer attached to the charging unit. 2. The image forming apparatus according to claim 1, wherein a layer thickness of the residual liquid developer remaining on the image carrier after transferring the toner image to the transfer medium is regulated to 30 μm or less. The developing means includes:
A developer tank in which the liquid developer is stored,
A developing roller for developing the electrostatic latent image with the liquid developer,
A roller member that supplies the liquid developer to the developing roller and regulates a layer thickness thereof,
A regulating means for regulating the layer thickness of the liquid developer on the roller member so that the layer thickness of the residual liquid developer on the image bearing member is 30 μm or less approaches or comes in contact with the roller member. The image forming apparatus according to claim 1, further comprising: 3. The image forming apparatus according to claim 2, wherein the charging unit and the cleaning member are positioned above a bottom surface of the developer tank facing a space defining the developer tank. 4. When the rotation center axis of the image carrier is the origin of the two-dimensional coordinates, the charging unit and the cleaning member are positioned in the third quadrant of the two-dimensional coordinates, and the developing roller is positioned in the fourth quadrant of the two-dimensional coordinates. The image forming apparatus according to claim 2, wherein: A contact portion between the charging unit and the image carrier and a contact portion between the charging unit and the cleaning member are positioned above a bottom surface of the developer tank facing a space defining the developer tank. The image forming apparatus according to claim 2, wherein: The image forming apparatus according to claim 2, wherein the cleaning member collects the residual liquid developer attached to the charging unit and guides the residual liquid developer to the developer tank at a position avoiding the developing roller. The image forming apparatus according to claim 1, wherein the charging unit is a rotatable roller member.

Images