JP3615461B2 - Liquid developing electrophotographic apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid developing electrophotographic apparatus using liquid toner, and more particularly to a liquid developing electrophotographic apparatus provided with a surplus carrier removing mechanism for removing excess oil from a toner layer that forms an image on an intermediate transfer member. .
[0002]
[Prior art]
FIG. 4 shows the entire configuration of a conventionally known liquid developing type electrophotographic apparatus (for example, see Japanese Patent Application Laid-Open No. 2000-056575). The photosensitive drum 10 is charged by the charging device 21 and then exposed by the exposure device 22 to form an electrostatic latent image. The prewetting device 23 applies, for example, silicone oil to the surface of the photosensitive drum 10.
[0003]
The developing device 24 is provided in association with yellow / magenta / cyan / black, and uses a high-viscosity, high-concentration liquid toner exhibiting non-volatility as a developer. The developing roller supplies the developer onto the photosensitive drum 10 and causes the toner particles of the developer to adhere to the photosensitive drum 10 in accordance with an electric field generated between the developing roller 10 and the photosensitive drum 10.
[0004]
The intermediate transfer roller 15 transfers the color toners attached to the photosensitive drum 10 one by one according to the electric field between the intermediate transfer roller 15 and the photosensitive drum 10. When the intermediate transfer roller 15 transfers the toner particles attached to the photosensitive drum 10 in accordance with the electric field between the photosensitive drum 10 and excessive prewetting and development that moves from the photosensitive drum 10 to the intermediate transfer roller 15 together with the toner particles. It is necessary to remove the oil consisting of the carrier in the toner layer. Therefore, in the illustrated apparatus, an oil removing roller 25 is provided on the intermediate transfer roller 15.
[0005]
The heating device 28 melts the toner attached to the intermediate transfer roller 15 by heating the surface of the intermediate transfer roller 15. Heating by the heating device 28 is performed after transferring all color toners. The pressure roller 19 fixes the toner on the intermediate transfer roller 15 melted by the heating device 28 to the printing medium. In the figure, 26 is a blade for scraping off residual toner, and 27 is a static eliminating device.
[0006]
The carrier solvent in the liquid development has a function of making the particles charged and uniformly dispersed in addition to preventing the scattering of toner particles of about 1 μm. In the development and electrostatic transfer processes, the toner particles are subjected to electric field action. It also plays the role of a “bridge” for easy movement.
[0007]
The carrier solvent in the liquid developing printer process is a necessary component for toner storage, toner conveyance / layer formation, development, and electrostatic transfer. However, the carrier solvent is unnecessary from the viewpoint of image quality after the fixing process to the paper medium. For these reasons, a volatile insulating liquid is currently used as a carrier solvent for many liquid developers (toners). However, liquid developers using a non-volatile carrier solvent have also been developed due to toner fixation in the apparatus due to carrier volatilization, the influence of the volatile carrier on the human body, and environmental problems, one of which is HVS (High-Viscous Silicone). ) Toner.
[0008]
In the case of a liquid developing toner using a non-volatile carrier solvent, the carrier solvent cannot volatilize the toner when the toner is heated and melted. Inhibiting the expression, the image quality and adhesive strength to the paper medium may not be fully satisfied.
[0009]
Further, in the system in which the superimposed image on the intermediate transfer member is melt-transferred onto a paper medium, the heated toner may be in a patchy state on the intermediate transfer member during heating. This is due to the relationship between the peelability of the intermediate transfer member surface, the melt viscosity (fluidity) of the toner, and the wettability of the carrier solvent.
[0010]
As described above, it is necessary to remove the non-volatile carrier solvent as much as possible until the fixing process to the paper medium. However, removal of the carrier solvent before heating is limited in removing the carrier solvent filled in the gaps between the toner particles. There is.
[0011]
From the above, the “carrier removal during heating” method is effective in which residual carriers in the toner particles are raised and removed when the toner is heated and melted. The carrier removal method during heating is performed by integrating toner particles (resin component) and heating the toner particles when the toner particles are heated and melted in a printer device in which a non-volatile carrier solvent remains in the toner image on the intermediate transfer member. The carrier solvent (liquid component) is separated by utilizing the strong electric field action force of the activated toner particles. However, when applying an electric field acting force to the heated molten toner, it is necessary to consider the influence on the roller member due to temperature and the mutual influence on other process conditions. It was not considered enough.
[0012]
[Problems to be solved by the invention]
An object of the present invention is to provide a material, a mechanism, and conditions for further effectively and stably removing the carrier liquid by further improving the carrier removal method during heating.
[0013]
Another object of the present invention is to perform optimum carrier removal according to the residual amount of carriers.
[0014]
[Means for Solving the Problems]
In the liquid developing electrophotographic apparatus of the present invention, liquid toner is used as a developer, the developer is supplied in contact with the image support on which an electrostatic latent image is formed, and between the image support and the image support. A developing unit that forms toner images by attaching toner particles of the developer to the image support according to an electric field generated; an intermediate transfer member for transferring a toner image on the image support; The toner image transferred to the intermediate transfer member is composed of a transfer fixing unit that heats and melts the toner image at a contact portion with the print medium and melts and transfers the toner image to the print medium. The intermediate transfer member includes an excess carrier removing mechanism having a carrier removing roller for removing excess oil from a toner layer forming an image thereon. The carrier removal roller is in contact with the toner layer heated at or near the melting temperature, and applies a bias voltage in a direction in which the toner particles are pressed against the intermediate transfer member that holds the image.
[0015]
The liquid developing electrophotographic apparatus of the present invention also includes an intermediate transfer roller for transferring a toner image on an image support and superimposing a plurality of color toner images as an intermediate transfer member, and an overlay on the intermediate transfer roller. The toner image can be transferred at once, and can be constituted by an intermediate transfer belt that is heated and melted at a contact portion with the print medium to melt and transfer to the print medium. Then, the rotation of the intermediate transfer belt is controlled according to the residual carrier amount on the intermediate transfer belt holding the heated toner layer.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail according to embodiments. FIG. 1 is a diagram showing a first configuration example of a liquid developing type electrophotographic apparatus embodying the present invention.
[0017]
First, with reference to FIG. 1, a general outline of a liquid developing electrophotographic apparatus including a transfer fixing unit, particularly a carrier removing mechanism, which is a feature of the present invention will be described. A developing unit is provided at the lowermost part of the apparatus, an intermediate transfer part is provided thereon, and a transfer fixing part is provided at the uppermost part of the apparatus. As described above, since the exemplary apparatus includes the transfer fixing unit that generates a large amount of heat at the top of the apparatus, the heat in the apparatus can be efficiently discharged. Further, since the developing unit for handling liquid toner is provided at the lowermost part of the apparatus, even if the liquid toner leaks, the print medium is hardly soiled.
[0018]
The developing unit is provided in association with yellow / magenta / cyan / black. Photosensitive drums (photoconductors) 11 to 14 are provided, respectively, and a charger for charging the photosensitive drums 11 to 14 to about 700 V is provided (not shown). The exposure indicated by the arrows is performed on the charged photosensitive drums 11 to 14 based on image data, for example, using laser light having a wavelength of 780 nm. As a result, an electrostatic latent image is formed on the photosensitive drums 11 to 14 so that the potential of the exposed portion is about 100V. Further, a static elimination device (not shown) is provided to neutralize the remaining potential on the photosensitive drums 11 to 14.
[0019]
The developing roller is biased to a predetermined voltage such as about 400 V to 600 V, and supplies the positively charged toner to the photosensitive drums 11 to 14 in accordance with the electric field between the developing rollers 11 to 14. As a result, toner is adhered to the exposed portions on the photosensitive drums 11 to 14 that are charged to about 100 V, and the electrostatic latent images on the photosensitive drums 11 to 14 are developed to form images. The toner supply roller is composed of one or a plurality of rollers for each color toner, and liquid toner having a toner viscosity of 400 to 4000 mPa · s and a carrier viscosity of 20 to 500 cSt, preferably 100 cSt, is supplied from the toner reservoir. The liquid toner is applied with a predetermined layer thickness (for example, 4 to 10 μm) on the developing roller by being conveyed while being thinly extended.
[0020]
The intermediate transfer roller 15 as the first intermediate transfer member is biased to about −800 V and transfers the toner attached to the photosensitive drums 11 to 14 in accordance with the electric field between the photosensitive drums 11 to 14. The intermediate transfer roller 15 first transfers, for example, yellow toner attached to the first photosensitive drum 11, and subsequently transfers, for example, magenta toner attached to the second photosensitive drum 12, Subsequently, for example, cyan toner attached to the third photosensitive drum 13 is transferred, and finally, for example, black toner attached to the fourth photosensitive drum 14 is transferred. As described above, the four-color toner images developed on the first to fourth photosensitive drums 11 to 14 are sequentially superimposed on the intermediate transfer roller 15 by rotating the intermediate transfer roller 15 four times, so that color An image is formed. The cleaning blade contacts the intermediate transfer roller at an appropriate timing, and removes toner and prewetting liquid remaining thereon.
[0021]
Thereafter, the four-color image is electrostatically transferred onto the intermediate transfer belt 16 having a belt structure as a second intermediate transfer member, and after the carrier liquid is removed by the carrier removal unit, the transferred toner image is It is melted by heating at the contact portion with the print medium, and melted and transferred to the print medium. The image formed with the liquid toner on the intermediate transfer belt 16 contains the carrier liquid, and the carrier oil is removed by the carrier removal unit.
[0022]
FIG. 2 is a diagram showing in detail the carrier removal unit of the electrophotographic apparatus shown in FIG. As shown in the figure, three carrier removing rollers are provided on the intermediate transfer belt 16 so as to contact the heat roller 18. These carrier removal rollers come into contact with the toner layer on the intermediate transfer belt heated to or near the melting temperature and remove excess oil therefrom. A bias voltage is applied to the carrier removal roller. For this bias, for example, a voltage of +2 KV is applied to the heat roller in the direction in which the toner particles are pressed against the intermediate transfer belt holding the image. A bias voltage of −2 KV is applied to the pressure roller 19 with respect to the heat roller for transfer fixing. The carrier removal roller is a conductive roller having a resistance value that is equal to or lower than the electric resistance value of the molten toner, and the surface thereof is mirror-finished, that is, smooth. And it has both the heat resistance that can withstand the heating temperature and the electric withstand voltage that can withstand the applied bias voltage. A blade for collecting the removed carrier is also provided. Note that a carrier removing belt having a belt configuration may be used instead of the illustrated carrier removing roller.
[0023]
The pressure applied to the intermediate transfer belt by a plurality of carrier removal rollers arranged for each roller is set so as to gradually increase the pressure applied to each roller, for example, as the removal of the carrier proceeds in the traveling direction of the intermediate transfer belt 16. Can do. Further, the pressure applied by the carrier removal roller can be adjusted based on the analysis result of the print pattern.
[0024]
The bias voltage applied to the heat roller 18 of the plurality of carrier removing rollers, and therefore the intermediate transfer belt, is lowered for each roller, for example, as the toner conductivity increases with the removal of the carrier. Can do. The bias voltage applied to the carrier removal roller can be adjusted based on the analysis result of the print pattern.
[0025]
As for the hardness of the plurality of carrier removal rollers arranged, a hard roller can be used for each roller, for example, as the carrier is removed.
[0026]
The surface roughness of the plurality of carrier removing rollers arranged can be more mirror-finished for each roller, for example, as the carrier is removed. It is desirable to arrange the rollers so that the rollers are rotated in such a direction as not to destroy the image depending on the polishing marks of the rollers at the time of finishing.
[0027]
The carrier removing roller further includes means for heating the roller by providing a heater and the like, and means for detecting the temperature of the carrier removing roller, and the carrier removing roller is controlled to maintain a constant temperature. It is possible to perform stable carrier removal with the electric resistance of the removing roller kept constant.
[0028]
The toner image on the intermediate transfer belt 16 is heated and melted by a heat roller 18 and is transferred and fixed to a print medium by a pressure roller 19 having a heater in cooperation with the heat roller 18.
[0029]
The transfer fixing unit includes the above-described pressure roller 19 and a plurality of conveying rollers, an electrostatic belt wound around the roller, and the above-described intermediate transfer belt 16. The electrostatic belt conveys the print medium by adsorbing the print medium by electrostatic force. Heating by the heat roller 18 improves the carrier removal efficiency and cooperates with the pressure roller 19 with a built-in heater to melt the toner image on the intermediate transfer belt 16 and transfer and fix it to the printing medium. It is. Thereafter, the intermediate transfer belt 16 thus heated needs to be cooled. This can be performed, for example, by cooling a roller (cooling roller) around which the intermediate transfer belt 16 is wound. The cooling is performed when the toner is transferred from the intermediate transfer roller 15 to the intermediate transfer belt 16, so that the toner melts to prevent a transfer failure and the intermediate transfer roller 15 is heated. This is to prevent the transmission.
[0030]
It is possible to control, for example, increase the speed of the intermediate transfer belt 16 at the time of melt transfer within a range that does not affect the throughput by using the time for superimposing a plurality of color toner images on the intermediate transfer roller 15. Further, by controlling the speed of the intermediate transfer belt 16, the toner image is controlled to rotate a plurality of times from the transfer from the intermediate transfer roller 15 to the intermediate transfer belt 16 until the toner image is melted and transferred to the printing medium. Can do. As a result, the carrier can be removed a plurality of times by the same carrier removing roller without lowering the throughput.
[0031]
Furthermore, it is possible to provide means for monitoring the rotational speed of the intermediate transfer belt 16 and changing the bias voltage applied to the carrier removal roller in accordance with the rotational speed. As rotation proceeds and carriers are removed, the optimum applied bias voltage will be different. Therefore, an optimum bias voltage is set according to the rotational speed.
[0032]
Further, it is possible to provide means for monitoring the rotation speed of the intermediate transfer belt 16 and changing the pressure applied to the carrier removal roller in accordance with the rotation speed. As the rotation proceeds and the carrier is removed, the optimum applied pressure varies. Therefore, an optimum pressure is set according to the rotational speed.
[0033]
Further, the state of the toner image on the melted intermediate transfer belt is detected, and when a large amount of carrier liquid remains, the intermediate transfer belt 16 is rotated more than in the normal sequence. That is, by idling, the number of times of passing through the carrier removal roller can be increased. Therefore, when the surface potential on the intermediate transfer belt 16 holding the heated toner layer is detected by a surface potentiometer and the residual carrier amount on the belt is calculated from a table describing the relationship, the residual carrier amount is large. The sequence can be changed to a sequence in which the intermediate transfer belt is rotated twice. Furthermore, in order to determine the amount of residual carrier, a reflection type optical sensor for detecting gloss that matches the incident angle and the reflection angle of light is provided on the intermediate transfer belt holding the heated toner layer, and the reflection is performed. The residual carrier amount can be determined using the output.
[0034]
A plurality of carrier removal rollers are in contact with each other, and each carrier removal roller can be contacted and retracted independently, and the total carrier considering the number of rotations of the intermediate transfer belt according to the residual carrier amount The number of contact of the removal roller can be finely controlled.
[0035]
The carrier removal roller made of semiconductive rubber or the like is configured to retract the carrier removal roller from the intermediate transfer belt 16 outside the printing region or during non-printing in order to prevent a resistance value change due to partial temperature rise.
[0036]
Also, in order to keep the electrical characteristics (resistance value, etc.) of the carrier removal roller stably, it is necessary to keep the carrier removal roller at a constant temperature. Therefore, the temperature of the carrier removal roller is controlled by having a heater heat source. For example, the carrier removal roller has a hollow pipe roller structure, a halogen lamp heater is built in the pipe roller, a temperature detection sensor is provided on the roller surface, and the heater is on / off controlled at a constant temperature, for example, 70 to 80 ° C. be able to. In the case where the carrier removal roller is not provided with a heater heat source, the temperature of the carrier removal roller can be raised to a certain value by heat conduction by being driven to rotate by the heated intermediate transfer belt 16. In this case, it is desirable to provide a temperature sensor for temperature detection on the surface of the carrier removal roller.
[0037]
As a method for monitoring the resistance value of the carrier removal roller, the resistance value is determined from the voltage and current values when the carrier removal roller is brought into contact with the cleaned intermediate transfer belt 16 and a voltage is applied to the intermediate transfer belt 16. It is possible to calculate and control the heating so that the resistance value falls within a predetermined range.
[0038]
In a system using one or a plurality of carrier removal rollers, it is desirable to set the temperature of the final carrier removal roller higher than the temperature of the intermediate transfer belt 16. The carrier liquid tends to ooze from the hot side to the cold side. Therefore, by setting the temperature of the final carrier removing roller higher than that of the intermediate transfer belt 16, the remaining carrier liquid oozes out between the intermediate transfer belt 16 side and the molten toner layer, thereby acting as a release material, and transferring Defects can be prevented.
[0039]
In the case of a full color printer, the transfer bias voltage applied to the intermediate transfer belt 16 may differ between single color printing and two or more color overlay printing. Since the potential difference (electric field strength) with respect to the intermediate transfer belt 16 is important for the carrier removal bias on the intermediate transfer belt 16, a carrier removal bias voltage corresponding to the number of superimposed colors of the toner image on the intermediate transfer belt 16, for example, single color In the case of printing, 1 KV is applied, and in the case of two-color superposition printing, 1.5 KV is applied.
[0040]
The current flowing from the carrier removal roller to which the bias voltage is applied flows to the intermediate transfer belt 16, and as a result, the potential of the intermediate transfer belt 16 may fluctuate, which also affects the overlay transfer onto the intermediate transfer belt 16. There is a fear. Therefore, the method of applying the bias voltage to the carrier removal roller is controlled by limiting so as not to flow an excessive current, for example, 1 mA or more.
[0041]
The blade that scrapes the carrier liquid from the carrier removal roller can be provided with a plurality of convex protrusions on the lower side in the direction of gravity. In FIG. 3, the carrier removing roller, the blade tip contacting the lower side, and the carrier liquid accumulated there can be seen. By providing the convex protrusion, the carrier liquid that adheres to and accumulates on the blade tip can be dripped quickly.
[0042]
【The invention's effect】
Although there was a limit to the removal of the carrier solvent filled in the voids between the toner particles in the carrier removal before heating, the present invention is able to remove the carrier that contacts the toner layer heated at or near the melting temperature. By applying a bias voltage in the direction of pressing the toner particles to the intermediate transfer member that includes the roller and holds the image, it is possible to remove the excess carrier sufficiently and reliably without disturbing the toner image.
[0043]
In addition, the present invention has an effect that optimum carrier removal can be performed according to the residual amount of carriers.
[Brief description of the drawings]
FIG. 1 is a diagram showing a first configuration example of a liquid developing type electrophotographic apparatus embodying the present invention.
FIG. 2 is a diagram showing in detail a carrier removal unit of the electrophotographic apparatus shown in FIG.
FIG. 3 is a diagram illustrating a blade configuration for scraping a carrier liquid from a carrier removal roller.
FIG. 4 shows an overall configuration of a conventionally known liquid developing type electrophotographic apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Photosensitive drum 11 First photosensitive drum 12 Second photosensitive drum 13 Third photosensitive drum 14 Fourth photosensitive drum 15 Intermediate transfer roller 16 Intermediate transfer belt 18 Heat roller 19 Pressure roller 21 Charging device 22 Exposure device 23 Pre Wet device 24 Developing device 26 Blade 27 Static elimination device 28 Heating device

Claims (25)

Using liquid toner as a developer, the developer is supplied in contact with the image support on which an electrostatic latent image is formed, and the development is performed according to an electric field generated between the image support and the image support. A developing unit that forms toner images by adhering toner particles to the image support, an intermediate transfer unit for transferring the toner image on the image support, and a toner image transferred to the intermediate transfer unit. In a liquid developing electrophotographic apparatus comprising a transfer fixing unit that is heated and melted at a contact portion with a print medium and melted and transferred to the print medium.
An excess carrier removing mechanism for removing excess oil from the toner layer that forms an image on the intermediate transfer portion;
The surplus carrier removing mechanism is a semiconductive material in which a bias voltage is applied in the direction in which toner particles are pressed against the intermediate transfer portion that holds an image and is in contact with a toner layer heated at or near the melting temperature. A liquid developing electrophotographic apparatus comprising a carrier removing roller or belt. The intermediate transfer unit includes a heat roller for heating and melting the transferred toner image to melt and transfer the toner image onto a printing medium, and an intermediate transfer belt wound thereon, and the carrier removal roller includes the heat transfer roller. 2. The liquid developing electrophotographic apparatus according to claim 1, wherein a plurality of the liquid developing electrophotographic apparatuses are arranged so as to contact the roller. The liquid developing electrophotographic apparatus according to claim 2, wherein a pressure applied to the intermediate transfer belt by the plurality of carrier removing rollers is set for each roller. The liquid developing electrophotographic apparatus according to claim 2, wherein an applied bias voltage to the intermediate transfer belt of the plurality of carrier removing rollers arranged is set for each roller. The liquid developing electrophotographic apparatus according to claim 2, wherein hardness of the plurality of carrier removing rollers arranged is set for each roller. The liquid developing electrophotographic apparatus according to claim 2, wherein a surface roughness of the plurality of carrier removing rollers is set for each roller. The liquid developing electrophotographic apparatus according to claim 3, wherein the pressure applied to the carrier removing roller is adjusted based on an analysis of a printing pattern. The liquid developing electrophotographic apparatus according to claim 4, wherein an applied bias voltage of the carrier removing roller is adjusted based on an analysis of a printing pattern. The liquid developing electrophotographic apparatus according to claim 2, wherein the carrier removing roller is disposed in a direction in which an image is not broken by a polishing eye of the roller. A means for heating the carrier removal roller and a means for detecting the temperature of the carrier removal roller are further provided, and the electric resistance of the carrier removal roller is kept constant by controlling to keep the carrier removal roller at a constant temperature. The liquid developing electrophotographic apparatus according to claim 1, wherein the removed carrier is removed. The intermediate transfer unit transfers the toner image on the image support to superimpose a plurality of color toner images, and transfers the toner image superimposed on the intermediate transfer roller at a time. And an intermediate transfer belt that melts and transfers to the print medium by heating and melting at the contact portion with the print medium, and affects the throughput by using the time to superimpose all the color toner images on the intermediate transfer roller. The liquid developing electrophotographic apparatus according to claim 1, wherein the speed of the intermediate transfer belt at the time of melt transfer is controlled within a range in which no toner is given. 12. The method according to claim 11, wherein the toner image is controlled to rotate a plurality of times from the time when the toner image is transferred from the intermediate transfer roller to the intermediate transfer belt until the intermediate transfer belt is melted and transferred to the printing medium by controlling the speed of the intermediate transfer belt. Liquid developing electrophotographic apparatus. 13. The liquid developing electrophotographic apparatus according to claim 12, further comprising means for monitoring the rotational speed of the intermediate transfer belt and changing a bias voltage applied to the carrier removal roller in accordance with the rotational speed. 13. The liquid developing electrophotographic apparatus according to claim 12, further comprising means for monitoring the rotation speed of the intermediate transfer belt and changing the pressure applied to the carrier removal roller in accordance with the rotation speed. The intermediate transfer unit transfers the toner image on the image support and superimposes a plurality of color toner images, and transfers the toner image superimposed on the intermediate transfer roller at a time. An intermediate transfer belt that is heated and melted at a contact portion with the print medium and melt-transferred to the print medium, detects a surface potential on the intermediate transfer belt that holds the heated toner layer, and remains on the belt 2. The liquid developing electrophotographic apparatus according to claim 1, wherein the carrier amount is indexed from a table describing the relationship, and the intermediate transfer belt is controlled to rotate twice when the residual carrier amount is large. A plurality of the carrier removal rollers are in contact with each other, and each carrier removal roller is configured to be able to contact and retreat independently, and the number of contact of the carrier removal roller is controlled according to the amount of residual carrier. 15. The liquid developing electrophotographic apparatus according to 15. The intermediate transfer unit transfers the toner image on the image support to superimpose a plurality of color toner images, and transfers the toner image superimposed on the intermediate transfer roller at a time. An intermediate transfer belt that is heated and melted at a contact portion with the print medium and melt-transferred to the print medium, and the incident angle and the reflection angle of light are made to coincide on the intermediate transfer belt that holds the heated toner layer. 2. A reflective optical sensor for detecting glossiness is provided, and the amount of residual carrier on the intermediate transfer belt is determined from the reflected output, and when the amount of residual carrier is large, the intermediate transfer belt is controlled to rotate twice. 2. A liquid developing electrophotographic apparatus according to 1. A plurality of the carrier removal rollers are in contact with each other, and each carrier removal roller is configured to be able to contact and retract independently, and the number of contact of the carrier removal roller is controlled according to the amount of residual carrier. The liquid developing electrophotographic apparatus according to 17. 2. The liquid developing electrophotographic apparatus according to claim 1, wherein the carrier removing roller is configured to retract the carrier removing roller from the intermediate transfer portion when outside the printing region or during non-printing in order to prevent a change in resistance value due to partial temperature rise. apparatus. 2. The liquid developing electrophotographic apparatus according to claim 1, wherein the carrier removing roller is driven and rotated by a heated intermediate transfer portion to raise the temperature of the carrier removing roller to a certain value by heat conduction. A carrier removal roller is brought into contact with the intermediate transfer portion, a resistance value is calculated from the voltage and current values when a voltage is applied to the intermediate transfer portion, and heating control is performed so that the resistance value falls within a predetermined range. The liquid developing electrophotographic apparatus according to claim 10 or 20. The liquid developing electrophotographic apparatus according to claim 1, wherein the temperature of the final carrier removing roller among the one or a plurality of carrier removing rollers is set higher than the temperature of the intermediate transfer unit. The liquid developing electrophotographic apparatus according to claim 1, wherein the bias voltage applied to the carrier removal roller is changed according to the number of superimposed colors of the toner image on the intermediate transfer unit. 2. The liquid developing electron according to claim 1, wherein the bias voltage applied to the carrier removal roller is limited to a low current that does not affect the overlay transfer onto the intermediate transfer portion by changing the potential of the intermediate transfer portion. Photo equipment. 2. The liquid according to claim 1, wherein the blade that scrapes the carrier liquid from the carrier removing roller has a plurality of convex protrusions on the lower side in the direction of gravity, and quickly drops the carrier liquid that adheres to and accumulates on the tip of the blade. Development electrophotographic apparatus.

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