JP7130478B2 - Separator - Google Patents

Description

The present invention relates to a separation device for separating toner and carrier liquid from a liquid developer.

2. Description of the Related Art Conventionally, there has been known an image forming apparatus that forms an image using a liquid developer containing toner and carrier liquid. In such an image forming apparatus, the liquid developer that has not been used in the image forming process is collected and recycled. In such recycling processing of the liquid developer, the toner particles, which are dispersoids in the liquid developer (liquid material), and the carrier liquid, which is a dispersion medium, are separated, and the carrier liquid is reused.

For example, a separation device has been proposed that includes an electrode roller, an electrode member, a supply section, a carrier recovery section, and a recovery roller, and uses an electric field to separate toner and carrier liquid from a liquid developer (Patent Reference 1).

Specifically, the electrode member is arranged with a gap between the electrode member and the outer surface of the electrode roller, and a voltage can be applied between the electrode member and the electrode roller so as to generate an electric field that moves the toner toward the electrode roller. The supply unit supplies the liquid developer to the gap between the electrode roller and the electrode member. The carrier recovery part is provided adjacent to the downstream side of the electrode member and recovers the carrier liquid. The recovery roller is arranged downstream of the carrier recovery section, and a voltage can be applied between the recovery roller and the electrode roller so as to generate an electric field for moving the toner from the electrode roller side.

JP 2016-224424 A

Here, in the separating apparatus described in Patent Document 1, for example, when the voltage application to the electrode member is stopped before the supply of the liquid developer by the supply unit is stopped, the liquid developer supplied to the gap is There is a possibility that it will be discharged without being separated.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a structure capable of reducing discharge of a liquid developer without being separated.

The present invention is a separation device for separating toner and carrier liquid by using an electric field from a liquid developer collected in an image forming section that forms an image using a liquid developer containing toner and carrier liquid. An electric field is generated between a conductive electrode roller rotating in a predetermined direction and an outer surface of the electrode roller and the electrode roller with a gap therebetween so that the toner moves toward the electrode roller. an electrode member to which such a voltage can be applied ; a storage portion for storing the liquid developer collected by the image forming portion; a supply portion for supplying the liquid developer from the storage portion to the gap; A carrier recovery unit that is provided adjacent to the downstream side of the electrode member with respect to the rotation direction and recovers the carrier liquid; and a collection roller to which a voltage that generates an electric field for moving toner from the electrode roller side can be applied, wherein the liquid developer is supplied by the supply unit, and the electrode roller and the collection roller rotate. , a voltage is applied to the electrode member and a voltage is applied to the collection roller to perform a separation operation for separating the toner and the carrier liquid from the liquid developer, and when the separation operation is completed, the supply stopping the supply of the liquid developer by the unit, then stopping the application of the voltage to the recovery roller, stopping the rotation of the electrode roller and the recovery roller, and stopping the application of the voltage to the electrode member. Characterized by

According to the present invention, discharge of the liquid developer without being separated can be reduced.

1 is a schematic configuration diagram of an image forming apparatus according to a first embodiment; FIG. FIG. 2 is a schematic configuration diagram showing a liquid developer transport path of the image forming apparatus according to the first embodiment; 4 is a control block diagram of the liquid developer conveying operation of the image forming apparatus according to the first embodiment; FIG. 4 is a flowchart showing control of the liquid developer conveying operation of the image forming apparatus according to the first embodiment; 1 is a perspective view of a separation/extraction device according to a first embodiment; FIG. 1 is a perspective view showing a part of the separation/extraction device according to the first embodiment. FIG. FIG. 2 is a cross-sectional view showing part of the separation/extraction device according to the first embodiment; FIG. 8 is an enlarged view of part A in FIG. 7 ; 4 is a flow chart showing control of liquid developer separation and extraction operations according to the first embodiment. FIG. 2 is a cross-sectional view showing a part of the separation/extraction device according to the first embodiment for explaining the flow of toner; FIG. 10 is a flow chart showing the control of the part corresponding to section B in FIG. 9 in the control of the operation of separating and extracting the liquid developer according to the second embodiment; FIG. FIG. 10 is a flowchart showing the control of the part corresponding to section B in FIG. 9 in the control of the separation and extraction of the liquid developer according to the third embodiment; FIG. FIG. 10 is a flow chart showing the control of the portion corresponding to section B in FIG. 9 in the control of the operation of separating and extracting the liquid developer according to the fourth embodiment; FIG.

<First Embodiment>
A first embodiment will be described with reference to FIGS. 1 to 10. FIG. First, the schematic configuration of the image forming apparatus of this embodiment will be described with reference to FIG.

[Image forming apparatus]
The image forming apparatus 100 of this embodiment is an electrophotographic digital printer that forms a toner image on a recording material (paper, sheet material such as an OHP sheet, etc.). The image forming apparatus 100 operates based on an image signal, transfers a toner image formed by the image forming unit 12 onto a sheet S as a recording material that is sequentially conveyed from the cassettes 11a and 11b, and then fixes the toner image. I am getting the image. An image signal is sent to the image forming apparatus 100 from an external terminal such as a scanner (not shown) or a personal computer.

The image forming section 12 includes a photosensitive drum 13 as an image carrier, a charger 14 , a laser exposure device 15 , a developer 16 and a drum cleaner 19 . The photosensitive drum 13 whose surface is charged by the charger 14 is irradiated with a laser beam E from the laser exposure device 15 according to an image signal, and an electrostatic latent image is formed on the photosensitive drum 13 . This electrostatic latent image is developed as a toner image by the developing device 16 . In this embodiment, the developing device 16 contains a liquid developer D as a liquid material in which powder toner as a dispersoid is dispersed in a carrier liquid as a dispersion medium. Development is performed using

The liquid developer D is produced by mixing and dispersing the toner T in the carrier liquid C at a predetermined ratio in the mixer 31 as a mixer, and is supplied to the developing device 16 . The carrier liquid C is contained in a carrier tank 32 as a carrier container (recovery container), and the toner T is contained in a toner tank 33 as a toner container. Then, the carrier liquid C or the toner T is supplied to the mixer 31 from the respective tanks according to the mixed state of the carrier liquid C and the toner T in the mixer 31 . The mixer 31 accommodates stirring blades driven by a motor (not shown), stirs and mixes the supplied carrier liquid C and the toner T, and disperses the toner T in the carrier liquid C. .

The liquid developer D supplied from the mixer 31 to the developing device 16 is coated (supplied) on the developing roller 18 as a developer carrying member by the coat roller 17 in the supply section 16a of the developing device 16, and used for development. be. The developing roller 18 carries and conveys a liquid developer on its surface, and develops the electrostatic latent image formed on the photosensitive drum 13 (on the image carrier) with toner. The carrier liquid C and toner T remaining on the developing roller 18 after development are recovered in the recovery section 16 b of the developing device 16 . Here, the coating of the liquid developer D from the coat roller 17 to the developing roller 18 and the development from the developing roller 18 to the electrostatic latent image on the photosensitive drum 13 are each performed using an electric field.

The toner image formed on the photosensitive drum 13 is transferred to the intermediate transfer roller 20 using an electric field and conveyed to the nip portion formed by the intermediate transfer roller 20 and the transfer roller 21 . A drum cleaner 19 collects the toner T and carrier liquid C remaining on the photosensitive drum 13 after the toner image is transferred to the intermediate transfer roller 20 . At least one of the intermediate transfer roller 20 and the transfer roller 21 may be an endless belt.

The sheets S accommodated in the cassettes 11a and 11b are conveyed toward the resist conveying section 23 by the feeding sections 22a and 22b including conveying rollers and the like. The registration conveying portion 23 conveys the sheet S to the nip portion between the intermediate transfer roller 20 and the transfer roller 21 in synchronization with the timing of the toner image transferred to the intermediate transfer roller 20 .

At the nip portion between the intermediate transfer roller 20 and the transfer roller 21, the toner image is transferred to the passing sheet S, and the sheet S onto which the toner image has been transferred is conveyed to the fixing device 25 by the conveying belt 24 and transferred to the sheet S. The toner image is fixed. The sheet S on which the toner image is fixed is discharged out of the machine, and the image process is completed.

The intermediate transfer roller 20 and the transfer roller 21 are provided with an intermediate transfer roller cleaner 26 and a transfer roller cleaner 27 for collecting the residual toner T and carrier liquid C, respectively.

[Conveyance of Liquid Developer]
Next, the conveyance of the liquid developer D in this embodiment will be described with reference to FIGS. 2 to 4. FIG. First, the developer collected by the image forming unit 12 such as the drum cleaner 19, the intermediate transfer roller cleaner 26, and the transfer roller cleaner 27 as described above is separated into toner and carrier liquid by the separating/extracting device 34 as a separating device. Separate and recycle the carrier liquid. The developer remaining on the developing roller 18 after development and recovered in the recovery section 16 b of the developing device 16 is returned to the mixer 31 , but may be transported to the separating/extracting device 34 .

The separation/extraction device 34, which will be described later in detail, separates the reusable carrier liquid and the waste liquid W containing impurities such as toner and paper powder when separating the carrier liquid and the toner. The waste liquid W is recovered in the waste liquid recovery container 35 .

More specific description will be given. Transport pipes from the carrier tank 32 and toner tank 33 to the mixer 31 are provided with solenoid valves 41 and 42 , respectively, to adjust the amounts of carrier liquid C and toner T supplied to the mixer 31 . Liquid developer D required for development is supplied from mixer 31 to developing device 16 using pump 44 .

The developer collected in the collection section 16 b of the developing device 16 is returned to the mixer 31 by the pump 43 . This is because the developer collected in the collection section 16b has not been used for development or the like and has hardly deteriorated.

The residual carrier liquid and toner collected by the drum cleaner 19, the intermediate transfer roller cleaner 26, and the transfer roller cleaner 27 are conveyed to the separation/extraction device 34 by pumps 48, 49, and 50, respectively.

The reusable carrier liquid separated by the separation/extraction device 34 is conveyed to the carrier tank 32 by the solenoid valve 45 . On the other hand, the waste liquid separated by the separating/extracting device 34 is properly conveyed to the waste liquid collecting container 35 by the solenoid valve 47 provided on the transport pipe by dropping under its own weight.

For transporting the liquid developer or the like, instead of using a pump, for example, if the liquid developer can be transported by falling under its own weight, a transport method using its own weight without providing a pump may be used.

As shown in FIG. 3, the pumps 43, 44, 48, 49, and 50 and the electromagnetic valves 41, 42, 45, and 47 are controlled by a CPU 200 as a control unit via a pump driver 201 and an electromagnetic valve driver 202, respectively. controlled. A pump 34c described later is also controlled by the CPU 200 via a pump driver 201, like the pump 43 described above. The CPU 200 controls each pump and the like based on the detection values of the agent amount detection device 160, the solid component concentration detection device 310, and the carrier liquid concentration detection device 34a, which will be described later.

Such a liquid developer conveying operation will be described with reference to FIGS. 2 and 3 and FIG. First, as shown in FIGS. 2 and 3, the developing device 16 is provided with a developer amount detecting device 160 that detects the amount of liquid developer in the developing device 16 . Further, the mixer 31 is provided with a solid component concentration detection device 310 for detecting the concentration of solid components such as toner in the mixer 31 . The solid component concentration detection device 310 includes, for example, a light-emitting portion and a light-receiving portion. . Since the amount of light received by the light receiving portion changes depending on the amount of the solid component in this portion, the concentration of the solid component in the mixer 31 can be detected from the change in the amount of light.

As shown in FIG. 4, the developer amount in the developing device 16 is detected by the developer amount detector 160 (S1). When the amount of developer in the developing device 16 is less than a predetermined amount (for example, 200±10 cc), the CPU 200 drives the pump 44 (S2) to adjust the amount of liquid developer in the developing device 16. . After the adjustment, the driving of the pump 44 is stopped (S3).

Next, the concentration of solid components in the mixer 31 is detected by the solid component concentration detector 310 (S4). If the concentration of the solid component in the mixer 31 is out of the predetermined range (eg, 10±0.5%), it is determined whether the concentration of the solid component is 10.5% or more (S5). Then, when the concentration of the solid component is 10.5% or more, the solenoid valve 41 is opened to supply the carrier liquid from the carrier tank 32 into the mixer 31 (S6). On the other hand, if the concentration of the solid component is less than 10.5%, that is, less than 9.5%, the solenoid valve 42 is opened to supply toner from the toner tank 33 into the mixer 31 (S7). Thereby, the concentration of the liquid developer in the mixer 31 is adjusted.

That is, when the toner concentration (solid component concentration) is high, the carrier liquid is supplied from the carrier tank 32 to the mixer 31 by the electromagnetic valve 41 . When the toner concentration is low, a liquid developer having a higher toner concentration than the liquid developer used in the mixer 31 is supplied from the toner tank 33 to the mixer 31 by the electromagnetic valve 42 .

When the concentration of the solid components in the mixer 31 reaches a predetermined range, the pump 44 is driven as necessary to supply the liquid developer with the adjusted concentration from the mixer 31 to the developing device 16 (S8). Then, image formation is started (S9), driving of the pumps 43, 48, 49, and 50 is also started (S10), and driving of the separation/extraction device 34 is also started (S11).

[Separation extraction device]
Next, the separation/extraction device 34 as a separation device will be described in detail with reference to FIGS. 5 to 8. FIG. The separating/extracting device 34 is a device that separates the liquid developer into toner and carrier liquid by using an electric field, and extracts the carrier liquid and the toner separately.

The liquid developer collected by the image forming section 12 such as the drum cleaner 19 as described above is conveyed from the inlet 34b of the separation/extraction device 34 into the liquid storage container 346 as indicated by the arrows in FIGS. be. Then, it is supplied to the buffer container 348 in the liquid storage container 346 . In this embodiment, the buffer container 348 is provided in the separation/extraction device 34, but it may be provided as a single container. The liquid developer supplied to the buffer container 348 is conveyed by the pump 34c as a supply unit and passes through the filter 34d.

The liquid developer that has passed through the filter 34d is put into a supply tray 346a, as shown in FIGS. 6 and 7, and is conveyed into a gap 347 between the electrode roller 342 and the coat electrode member 341 by the pump 34c. (See FIG. 7). That is, when the pump 34c is driven, the liquid developer supplied to the buffer container 348 is supplied to the upstream end portion 347a (FIG. 7) of the electrode roller 342 in the gap 347 through the supply tray 346a.

In addition to the pump, the supply unit may be a supply roller arranged in contact with or in close proximity to the electrode roller 342 . For example, instead of the supply tray, a storage tank capable of storing the liquid developer is arranged like a bucket, and the liquid developer recovered as described above is stored in this storage tank. Then, the supply roller is arranged so as to come into contact with the liquid developer stored in the storage tank. When the supply roller rotates while the liquid developer is stored in the storage tank, the liquid developer is pumped up on the surface layer of the supply roller. Then, the liquid developer is conveyed into the gap 347 by, for example, scraping off the liquid developer with a blade member in contact with the supply roller.

In this configuration, the supply roller may be driven separately from the electrode roller 342 or may be driven by the same driving source as the electrode roller 342 . Furthermore, the supply roller may be brought into contact with the electrode roller 342 and rotated by the electrode roller 342 . Further, the member for scraping off the liquid developer from the supply roller is not limited to the blade member. For example, a configuration other than a blade shape, or a brush or the like may be used. Furthermore, although the liquid developer is conveyed by the pump 34c in this embodiment, it may be conveyed as the electrode roller 342 rotates.

In the case of this embodiment, as will be described later in detail, the liquid developer that has been put into the supply tray 346a and fed into the gap 347 by the pump 34c is separated into toner and carrier liquid in the separating/extracting device 34. FIG. The extracted toner is sent to the waste liquid collection container 35 and the extracted carrier liquid is conveyed to the carrier tank 32 .

Next, the configuration for separating and extracting the toner and the carrier liquid in the separation/extraction device 34 will be described in detail. As shown in FIGS. 6 and 7, the liquid storage container 346 includes a coated electrode member 341 as an electrode member, an electrode roller 342 as a conductive roller, a toner recovery device 350, and the like. The liquid storage container 346 is a container capable of storing the liquid developer, and includes the above-described supply tray 346a and a discharge portion 346b as a carrier recovery portion for discharging reusable carrier liquid as will be described later. , and a recovery unit 354 for recovering the waste developer.

The electrode roller 342 is a conductive roller in which an elastic layer of urethane rubber is integrally formed on the surface layer of a metal core made of, for example, solid stainless steel and having an outer diameter of φ40 mm. As shown in FIG. 3, the electrode roller 342 is externally driven by a drive motor 205 as a drive source, and rotates in a predetermined direction (direction of arrows in FIGS. 6 and 7). In this embodiment, the rotational speed of the drive motor 205 is 2000 rpm. Then, the electrode roller 342 rotates at a rotational speed of, for example, 400 rpm by decelerating the rotation of the drive motor 205 by a speed reducer. The voltage applying device 345 and the drive motor 205 are controlled by the CPU 200 via the high-voltage driver 204 and the motor driver 203, respectively.

As shown in FIGS. 7 and 8, the coat electrode member 341 is arranged with a gap 347 interposed between a part of the outer surface of the electrode roller 342 and the electrode roller 342 . A supply tray 346a is connected to an upstream end portion 347a of the gap 347 in the rotation direction of the electrode roller 342 . Then, the liquid developer put into the supply tray 346a as described above is supplied into the gap 347 from the upstream end 347a by the pump 34c (FIG. 5). Both ends of the gap 347 in the rotation axis direction of the electrode roller 342 are sealed, and the liquid developer supplied to the gap 347 is conveyed downstream in the rotation direction through the gap 347 as the electrode roller 342 rotates. .

A discharge portion 346b as a carrier recovery portion is connected to a downstream end portion 347b of the gap 347 in the rotation direction of the electrode roller 342 (see FIG. 6). The upstream end 347a is arranged above the downstream end 347b in the direction of gravity. In addition, the discharge portion 346b is provided below the upstream end portion 347a of the electrode roller 342 in the rotation direction of the gap 347 in the direction of gravity and adjacent to the downstream side of the coat electrode member 341 with respect to the rotation direction of the electrode roller 342, The carrier liquid is recovered from the electrode roller 342 . Then, the liquid developer that has passed through the gap 347 is sent from the discharge portion 346b to the carrier tank 32 through the transport pipe 346c (see FIGS. 2 and 6).

The transport pipe 346c is also connected to a route for returning the discharged liquid developer to the separation/extraction device 34 again. The discharge portion 346b is provided with a carrier liquid concentration detection device 34a for detecting the toner concentration in the carrier liquid of the liquid developer sent into the discharge portion 346b. The configuration of the carrier liquid concentration detection device 34a is the same as that of the solid component concentration detection device 310 described above. Then, when the toner concentration of the liquid developer sent to the discharge portion 346b is greater than a predetermined value (for example, 0.02%), it is returned to the separation/extraction device 34 again to separate the toner and the carrier liquid. I am trying to do

This is because, for example, an abnormal situation such as the power being turned off during operation of the separation/extraction device 34 occurs, and the separation/extraction device 34 cannot sufficiently separate the carrier liquid and the toner. In such a case, the toner density of the liquid developer sent to the discharge portion 346b becomes higher than the predetermined value, so in this case, the liquid developer is returned to the separation/extraction device 34. FIG. Normally, as will be described later, the toner and the carrier liquid are separated by the liquid developer passing through the gap 347, and the extracted carrier liquid is sent to the discharge portion 346b. Therefore, the toner density of the liquid developer sent to the discharge portion 346b is equal to or lower than the predetermined value, and the liquid developer is sent to the carrier tank 32 without being returned to the separation/extraction device 34 . Incidentally, the path returning to the separation/extraction device 34 in this way may be omitted.

As described above, in the coat electrode member 341 arranged with the electrode roller 342 and the gap 347 interposed therebetween, at least the surface of the portion 341x through which the liquid passes is made of a conductive material. Also, the coated electrode member 341 is made of, for example, solid stainless steel and has a width of 400 mm. The portion 341x through which the liquid passes has a shape that accommodates a part of the electrode roller 342, and the surface of this portion 341x facing the electrode roller 342 is a predetermined distance (that is, the gap 347) from the surface of the electrode roller 342. ) has a curved shape. This predetermined distance is, for example, 0.2 mm.

As shown in FIG. 3, the coat electrode member 341, the electrode roller 342, and the collecting roller 351, which will be described later, are connected to a voltage applying device 345 as voltage applying means. A voltage can be applied between the coat electrode member 341 and the electrode roller 342 by a voltage applying device 345 so that an electric field is generated to move the toner toward the electrode roller 342 (electrode roller side). That is, a voltage is applied to the gap 347 to generate an electric field that attracts the toner to the electrode roller 342 .

In this embodiment, since the toner is negatively charged by the charge control agent, for example, minus 300 V is applied to the electrode roller 342 and minus 1000 V is applied to the coated electrode member 341 . Toner in the liquid developer passing through the gap 347 is moved from the coat electrode member 341 to the electrode roller 342 . As a result, while the liquid developer is passing through the gap 347, the toner is carried on the electrode roller 342, and the toner and the carrier liquid are separated. The separated carrier liquid is discharged to the discharge portion 346b connected to the downstream end portion 347b of the gap 347 and sent to the carrier tank 32 as a recovery container as described above.

The toner recovery device 350 is located downstream of the coat electrode member 341 with respect to the rotation direction of the electrode roller 342 and recovers the toner carried on the electrode roller 342 . The toner recovery device 350 has a recovery roller 351, a voltage application device 345 as recovery voltage application means, and a blade member 352 as a scraping member.

The collection roller 351 is a conductive roller made of, for example, solid stainless steel and having an outer diameter of φ20 mm, and is arranged so as to contact the electrode roller 342 . Then, the collection roller 351 contacts the electrode roller 342 and is driven to rotate in the direction of the arrow in FIGS. Note that the rotation speed of the collection roller 351 is, for example, 800 rpm. That is, the recovery roller 351 is positioned downstream of the discharging portion 346 b and upstream of the coat electrode member 341 with respect to the rotation direction of the electrode roller 342 , contacts the electrode roller 342 and faces the electrode roller 342 . Position rotates forward of each other. In this embodiment, the recovery roller 351 rotates following the electrode roller 342, but it may be configured to rotate by being driven by an external driving motor.

The electrode roller 342 and the recovery roller 351 are arranged substantially parallel to each other, and are rotatably supported at both ends in the direction of the rotation axis by the frame that constitutes the liquid storage container 346 . Further, biasing mechanisms such as springs are provided at both ends of the collecting roller 351 . The collecting roller 351 is urged toward the electrode roller 342 by the urging mechanism to elastically deform the electrode roller 342 . The pressing force of the recovery roller 351 against the electrode roller 342 by the biasing mechanism is, for example, 3 kgf (29.4 N).

Note that the coating electrode member 341 and the recovery roller 351 are positioned with reference to the electrode roller 342, and the electrode roller 342 serves as a positional reference for these members.

As shown in FIG. 3, the voltage applying device 345 is connected to the electrode roller 342 and the collection roller 351, and an electric field is generated between the collection roller 351 and the electrode roller 342 to move the toner toward the collection roller. Apply voltage as follows. The voltage application device 345 is configured to be able to apply voltage to the coat electrode member 341 and the recovery roller 351 separately and to stop applying the voltage separately. That is, the voltage applying device 345 can apply voltage to the coat electrode member 341 without applying voltage to the recovery roller 351 , and can apply voltage to the recovery roller 351 without applying voltage to the coat electrode member 341 . It is possible. In addition, the voltage application device 345 can stop applying voltage to the coat electrode member 341 after stopping the voltage application to the collection roller 351 , and after applying the voltage to the coat electrode member 341 , the voltage application to the collection roller 351 can be stopped. can be stopped.

In the present embodiment, the voltage application device 345 can simultaneously apply voltage to the electrode roller 342 and the recovery roller 351 and simultaneously stop voltage application, and can independently apply voltage to the coat electrode member 341. And the application of voltage can be stopped. However, it is also possible to make it possible to independently apply a voltage to the collection roller 351 and to stop the voltage application, and to make it possible to simultaneously apply a voltage to the coat electrode member 341 and the electrode roller 342 and to simultaneously stop the voltage application. Alternatively, it may be possible to apply the voltage and stop applying the voltage at different timings. In this embodiment, for example, minus 300 V is applied to the electrode roller 342 and minus 200 V is applied to the collection roller 351 . The toner carried by the electrode roller 342 and transported to the recovery roller 351 is moved from the electrode roller 342 to the recovery roller 351 .

The blade member 352 comes into contact with the collecting roller 351 and scrapes the toner on the collecting roller. The blade member 352 is disposed on the downstream side of the recovery roller 351 in the rotational direction of the position where the electrode roller 342 and the recovery roller 351 are in contact, so as to contact the recovery roller 351 in the counter direction. The blade member 352 is biased so that the tip portion 352 a contacts the surface of the collection roller 351 . Note that the counter direction is the direction in which the tip portion of the blade member 352 that contacts the recovery roller 351 faces is opposite to the tangential direction along the rotation direction of the recovery roller 351 . The blade member 352 is a plate-like member extending along the longitudinal direction (rotational axis direction) of the collection roller 351, and is made of stainless steel, for example.

The toner moved from the electrode roller 342 to the recovery roller 351 as described above is scraped off by the blade member 352 and sent to the recovery section 354 as a toner recovery section. The toner collected by the collecting unit 354 is sent to the waste liquid collecting container 35 as described above. Note that the scraping member that scrapes the toner from the collection roller 351 is not limited to the blade member. For example, a configuration other than a blade shape, or a brush or the like may be used.

[Control Flow of Separation and Extraction of Liquid Developer]
Next, the control flow of the operation of separating and extracting the liquid developer in this embodiment configured as described above will be described with reference to FIGS. 9 and 10. FIG. First, the developer collected by the drum cleaner 19 , the intermediate transfer roller cleaner 26 , and the transfer roller cleaner 27 is conveyed to the separation/extraction device 34 by driving the pumps 48 , 49 , and 50 . After a predetermined amount of developer has been sent to the separation/extraction device 34, the pumps 48, 49 and 50 are stopped (S21).

Next, voltage application is started (ON) only to the coat electrode member 341 (S22). In this embodiment, minus 1000 V is applied to the coat electrode member 341 . The voltage application timing is, for example, 100 msec after the pumps 48, 49 and 50 stop. The application of the voltage to the coat electrode member 341 may be started at the same time as the pumps 48, 49, and 50 are stopped, or before they are stopped. At this time, no voltage is applied to the electrode roller 342 (OFF). That is, the electrode roller 342 is at 0V. Therefore, a voltage is applied between the coat electrode member 341 and the electrode roller 342 so as to generate an electric field that moves the toner toward the electrode roller 342 . Therefore, the toner in the liquid developer moves to the electrode roller 342 side, and the carrier liquid having no charge remains on the coated electrode member 341 side. That is, even if the liquid developer is mistakenly mixed in the gap 347 or remains there, it can be separated.

Next, the supply of the liquid developer by the pump 34c is started (S23). The timing of the start of supply (the start of driving of the pump 34c) is, for example, 100 msec after the start of voltage application to the coat electrode member 341. FIG. It should be noted that the driving of the pump 34c may be started at the same time as the voltage application to the coat electrode member 341 is started.

Next, the driving motor 205 is started to rotate the electrode roller 342 and the collecting roller 351 (S24). The timing to start driving is, for example, 100 msec after the start of supply. This time is preferably the time required for liquid developer to reach upstream end 347a from pump 34c. The driving of the drive motor 205 may be started at the same time as the driving of the pump 34c. As a result, the liquid developer is conveyed as the electrode roller 342 rotates. At this time, the recovery roller 351 rotates following the electrode roller 342 .

Next, voltage application to the electrode roller 342 and the collection roller 351 is started (ON) (S25). In this embodiment, a voltage of minus 300 V is applied to the electrode roller 342 and a voltage of minus 200 V is applied to the recovery roller 351 . The voltage application timing is, for example, 100 msec after the start of driving of the drive motor 205 . This time is preferably the time required for the liquid developer to reach the nip portion between the electrode roller 342 and the collection roller 351 from the upstream end portion 347a. As a result, a voltage is applied between the collecting roller 351 and the electrode roller 342 so as to generate an electric field that moves the toner toward the collecting roller.

That is, in this embodiment, first, voltage application to the coat electrode member 341 is started. Next, after the supply of the liquid developer from the pump 34c is started and the rotation of the electrode roller 342 and the recovery roller 351 is started, the voltage application to the recovery roller 351 is started. In particular, in this embodiment, voltage application to the coat electrode member 341 is started, and after the pump 34c starts supplying the liquid developer, the electrode roller 342 and the collection roller 351 start rotating, and then, Application of voltage to the collection roller 351 is started. In this way, by turning on the voltage application only to the coat electrode member 341 before the supply of the liquid developer by the pump 34c is started, the liquid developer supplied to the gap 347 is discharged to the discharge portion 346b without being separated. It is possible to reduce the risk of contamination.

Further, the voltage application to the collection roller 351 is started at the timing when the liquid developer almost reaches the nip portion between the electrode roller 342 and the collection roller 351 . At this time, in this embodiment, the voltage is also applied to the electrode roller 342 . As described above, an electric field is generated between the coat electrode member 341 and the electrode roller 342 to move the toner toward the electrode roller 342, and an electric field is generated between the collecting roller 351 and the electrode roller 342 to move the toner toward the collecting roller. voltage is applied to For this reason, the toner in the liquid developer first moves to the electrode roller 342 side and then moves to the collection roller 351 side. The carrier liquid having no charge remains on the coated electrode member 341 side.

That is, as shown in FIG. 10, the toner T (solid line in FIG. 10) in the liquid developer passing through the gap 347 is electrically attracted to the electrode roller 342 and is electrically repelled from the coat electrode member 341. receive. As a result, the toner T is electrically urged toward the electrode roller 342 . At this time, the toner T layer is present on the electrode roller 342 side, and the carrier liquid C layer is present on the toner T layer. The liquid having the toner T layer and the carrier liquid C layer is conveyed to the collection roller 351 by the rotation of the electrode roller 342 , and the toner T layer is moved to the collection roller 351 by the electric field.

The toner T in the liquid developer that has passed through the gap 347 and is conveyed to the recovery roller 351 by the electrode roller 342 in this way is electrically attracted to the recovery roller 351 and is electrically repelled by the electrode roller 342 . . As a result, the toner is electrically urged in a direction away from the electrode roller 342, that is, toward the collection roller 351 side. At this time, the carrier liquid C is divided into the electrode roller 342 side and the recovery roller 351 side at a predetermined ratio, and the carrier liquid C layer (broken line in FIG. 10) divided on the electrode roller 342 side The rotation transports it to the upstream end 347 a of the gap 347 . In other words, the carrier liquid C split to the electrode roller 342 side with the recovery roller 351 is returned to the inlet of the gap 347 . Then, it merges with the liquid developer supplied from the supply tray 346a and is conveyed to the gap 347 again.

If the electric fields described above can be generated between the coating electrode member 341 and the electrode roller 342 and between the collecting roller 351 and the electrode roller 342, for example, voltage will not be applied to the electrode roller 342. It is not necessary to apply.

Further, if the control is to start applying the voltage to the collection roller 351 after the supply of the liquid developer by the pump 34c and the start of the rotation of the electrode roller 342 and the collection roller 351, the above-described order is not necessary. Also good. For example, after driving the driving motor 205 or simultaneously driving the pump 34c, the voltage application to the coat electrode member 341 and the collection roller 351 may be started. The voltage application to the coat electrode member 341 may be performed before, after, or at the same time as the voltage application to the collection roller 351 is started.

The toner electrically adhered to the collection roller 351 is scraped off by the blade member 352 . Here, the electromagnetic valve 47 is opened (S26). As a result, the toner scraped off by the blade member 352 drops under its own weight and is recovered from the recovery portion 354 to the waste liquid recovery container 35 . Note that the toner may be discarded or reused.

Further, the carrier liquid discharged from the downstream end portion 347b of the gap 347 to the discharging portion 346b has its toner concentration detected by the carrier liquid concentration detection device 34a, and the detected toner concentration reaches a predetermined value (for example, 0.02%). It is determined whether or not (S27). If the toner concentration is equal to or less than the predetermined value, the solenoid valve 45 is opened to send the carrier liquid to the carrier tank 32 (S28). When the separation and extraction of the carrier liquid from inside the separation and extraction device 34 is completed (S29), the solenoid valves 45 and 47 are closed (S30).

Next, the supply of the liquid developer by the pump 34c is stopped (S31). The timing of stopping the supply (stopping the driving of the pump 34c) is, for example, 100 msec after the solenoid valves 45 and 47 are closed.

Next, voltage application to the electrode roller 342 and the recovery roller 351 is stopped (OFF) (S32). The voltage application stop timing is, for example, 100 msec after the supply stop. This time is preferably set to a time during which the liquid developer last supplied from the pump 34c can be separated from the upstream end 347a to the downstream end 347b. Alternatively, this time is preferably set so that the liquid developer last supplied from the pump 34c reaches the nip portion between the electrode roller 342 and the collecting roller 351 and the separated toner can be collected.

Next, the driving of the drive motor 205 is stopped to stop the rotation of the electrode roller 342 and the collection roller 351 (S33). The timing of stopping the driving of the driving motor 205 is, for example, 100 msec after the voltage application to the electrode roller 342 and the collection roller 351 is stopped. The drive motor 205 may be stopped at the same time as the voltage application to the electrode roller 342 and collection roller 351 is stopped.

Next, voltage application to the coat electrode member 341 is stopped (OFF) (S34). The voltage application stop timing is, for example, 100 msec after the drive motor 205 stops driving. The voltage application to the coated electrode member 341 may be stopped at the same time as the drive motor 205 is stopped.

Next, the pumps 48, 49, and 50 transport a predetermined amount of residual developer to the separation/extraction device 34 again for the next separation process. Such operations are repeated.

Note that the separation/extraction device 34 of the present embodiment can extract 88.0 cc of carrier liquid from 100.0 cc of liquid developer (containing 90.0 cc of carrier liquid and 10.0 cc of toner). Also, the time required for one separation process is, for example, 30 seconds, and in this case, it is possible to handle up to a process speed of 800 mm/s.

In the case of this embodiment, the supply of the liquid developer by the pump 34c is stopped, the application of the voltage to the collection roller 351 is stopped, the rotation of the electrode roller 342 and the collection roller 351 is stopped, and the coating electrode member is stopped. 341 voltage application is stopped. Specifically, the driving of the pump 34c is stopped, and then the driving of the drive motor 205 is stopped after or at the same time as the voltage application to the recovery roller 351 is stopped. Further, the voltage application to the coated electrode member 341 is stopped after the driving of the drive motor 205 is stopped or at the same time as the driving is stopped.

Here, if the application of the voltage to the coat electrode member 341 or the drive motor 205 is stopped before the driving of the pump 34c is stopped, the liquid developer that is finally supplied to the gap 347 is not separated. There is a risk that it will remain in the gap 347 or be discharged from the discharge portion 346b. The liquid developer remaining in the gap 347 without being separated may be discharged from the discharging portion 346b without being separated when the separating/extracting device 34 is next driven.

If the liquid developer is discharged from the discharge portion 346b without being separated in this manner, the carrier liquid with high purity cannot be obtained and may not be reused. Separation and extraction are applied. Furthermore, it may be necessary to replace the carrier liquid in the tank that stores the recycled carrier liquid.

In contrast, in the case of the present embodiment, after stopping the driving of the pump 34c, the voltage application to the collection roller 351 and the electrode roller 342 is stopped, the drive motor 205 is stopped, and the voltage application to the coated electrode member 341 is stopped. Is going. Therefore, the driving of the pump 34c is stopped, and the liquid developer finally supplied to the gap 347 stays in the electric field between the coat electrode member 341 and the electrode roller 342 for a while so that the toner moves toward the electrode roller 342 side. is formed, and is conveyed through the gap 347 .

As a result, the liquid developer last supplied to the gap 347 is separated into toner and carrier liquid, and the carrier liquid is discharged to the discharge portion 346b. On the other hand, the toner is conveyed to the collecting roller 351 and collected by the collecting roller 351 . In this manner, after stopping the driving of the pump 34c, the voltage application to the collection roller 351 and the coat electrode member 341 is stopped, and the driving of the drive motor 205 is stopped. It is possible to reduce the amount of remaining or being discharged from the discharge portion 346b.

In particular, if the liquid developer last supplied to the gap 347 reaches the downstream end 347b from the upstream end 347a and the voltage application to the coat electrode member 341 is stopped after the liquid developer is separated, the gap 347 The separation of the liquid developer lastly supplied to . Further, if the voltage application to the collecting roller 351 is stopped at the timing when the liquid developer finally supplied to the gap 347 reaches the nip portion between the electrode roller 342 and the collecting roller 351 or after reaching the nip portion, the toner can be collected more reliably. .

The timing of stopping the voltage application to the coat electrode member 341 may be after the driving of the pump 34c is stopped, and before the last liquid developer supplied to the gap 347 reaches the downstream end portion 347b. Also good. Even in this case, since the liquid developer is separated while the voltage is being applied, the liquid developer discharged from the discharging portion 346b without being separated can be reduced. Also, the timing of stopping the voltage application to the recovery roller 351 may be before the nip portion between the electrode roller 342 and the recovery roller 351 is reached. Even in this case, since even a small amount of the separated toner is collected by the collection roller 351, the toner that is not collected by the collection roller 351 can be reduced.

Further, in the above-described embodiments, an example in which toner is used as a dispersoid and a carrier liquid is used as a dispersion medium has been described, but the present invention is applicable to any dispersoid and dispersion medium that can be separated by an electric field. For example, the dispersoid may be a charge control agent and the dispersion medium may be a carrier liquid.

<Second embodiment>
A second embodiment will be described using FIG. 11 while referring to FIGS. It should be noted that the present embodiment is the same as the first embodiment except for the control in section B of the flowchart of FIG. 9 of the first embodiment. For this reason, the same reference numerals are used for the same configurations as in the first embodiment, and the description and illustration are omitted or simplified, and the following description focuses on the points different from the first embodiment.

A control flow of the operation of separating and extracting the liquid developer in this embodiment will be described with reference to FIG. 9 and FIG. 11 . As shown in FIG. 9, when the separation and extraction of the carrier liquid from inside the separation/extraction device 34 is completed (S29 in FIG. 9), the electromagnetic valves 45 and 47 are closed (S30 in FIG. 9).

Next, the supply of the liquid developer by the pump 34c is stopped (S31-A). The timing of stopping the supply (stopping the driving of the pump 34c) is, for example, 100 msec after the solenoid valves 45 and 47 are closed.

Next, the voltage application to the electrode roller 342 and the collection roller 351 is stopped (OFF) (S32-A). The voltage application stop timing is, for example, 100 msec after the supply stop. This time is preferably set to a time during which the liquid developer last supplied from the pump 34c can be separated from the upstream end 347a to the downstream end 347b. Alternatively, this time is preferably set so that the liquid developer last supplied from the pump 34c reaches the nip portion between the electrode roller 342 and the collecting roller 351 and the separated toner can be collected.

Next, the voltage application to the coat electrode member 341 is stopped (turned off) (S33-A). The timing of stopping voltage application to the coat electrode member 341 is, for example, 100 msec after stopping voltage application to the electrode roller 342 and the recovery roller 351 .

Next, the driving of the driving motor 205 is stopped to stop the rotation of the electrode roller 342 and the recovery roller 351 (S34-A). The driving stop timing is, for example, 100 msec after the voltage application to the coat electrode member 341 is stopped.

That is, in this embodiment, after stopping the driving of the pump 34c and then stopping the voltage application to the collection roller 351, the voltage application to the coat electrode member 341 is stopped and the driving of the driving motor 205 is stopped. As a result, while the electrode roller 342 is rotating, a voltage is applied to the coat electrode member 341 and the collection roller 351, so that the liquid developer can be separated and the separated toner can be collected. After S34-A, this control ends, and preparations are made for separation processing.

In this embodiment as well, after the pump 34c is stopped, voltage application to the recovery roller 351 and the coat electrode member 341 is stopped, and driving of the drive motor 205 is stopped. Ejection without being separated can be reduced.

Further, in the case of the present embodiment, the electrode roller 342 and the recovery roller 351 stop rotating after the voltage application to the coat electrode member 341 and the recovery roller 351 is stopped. Therefore, damage to the electrode roller 342 can be reduced. That is, if a voltage is applied to the coat electrode member 341 while the rotation of the electrode roller 342 is stopped, the voltage continues to be applied to the same portion of the electrode roller 342, which may damage the electrode roller 342. . On the other hand, in the case of the present embodiment, the rotation of the electrode roller 342 is stopped after the application of the voltage to the coat electrode member 341 is stopped. It is possible to prevent and reduce damage to the electrode roller 342 .

<Third Embodiment>
A third embodiment will be described using FIG. 12 while referring to FIGS. It should be noted that the present embodiment is the same as the first embodiment except for the control in section B of the flowchart of FIG. 9 of the first embodiment. For this reason, the same reference numerals are used for the same configurations as in the first embodiment, and the description and illustration are omitted or simplified, and the following description focuses on the points different from the first embodiment.

A control flow of the operation of separating and extracting the liquid developer in this embodiment will be described with reference to FIG. 9 and FIG. As shown in FIG. 9, when the separation and extraction of the carrier liquid from inside the separation/extraction device 34 is completed (S29 in FIG. 9), the electromagnetic valves 45 and 47 are closed (S30 in FIG. 9).

Next, the supply of the liquid developer by the pump 34c is stopped (S31-B). The timing of stopping the supply (stopping the driving of the pump 34c) is, for example, 100 msec after the solenoid valves 45 and 47 are closed.

Next, the voltage application to the coat electrode member 341 is stopped (OFF) (S32-B). The voltage application stop timing is, for example, 100 msec after the supply stop. This time is preferably set to a time during which the liquid developer last supplied from the pump 34c can be separated from the upstream end 347a to the downstream end 347b. As a result, even if the liquid developer is accidentally mixed in or remains in the gap 347, it can be separated until the voltage application to the coat electrode member 341 is stopped.

Next, the voltage application to the electrode roller 342 and the collection roller 351 is stopped (OFF) (S33-B). The voltage application to the electrode roller 342 and the collecting roller 351 is stopped at, for example, 100 msec after the voltage application to the coat electrode member 341 is stopped. This time is preferably a time during which the liquid developer last supplied from the pump 34c reaches the nip portion between the electrode roller 342 and the collecting roller 351 and the separated toner can be collected. The voltage application to the electrode roller 342 and the collection roller 351 may be stopped at the same time as the voltage application to the coat electrode member 341 is stopped.

Next, the driving of the drive motor 205 is stopped to stop the rotation of the electrode roller 342 and the collection roller 351 (S34-B). The driving stop timing is, for example, 100 msec after the voltage application to the electrode roller 342 and the collection roller 351 is stopped. The drive motor 205 may be stopped at the same time as the voltage application to the electrode roller 342 and collection roller 351 is stopped.

In this embodiment as well, after the pump 34c is stopped, voltage application to the recovery roller 351 and the coat electrode member 341 is stopped, and driving of the drive motor 205 is stopped. Ejection without being separated can be reduced. Further, in the case of the present embodiment, the electrode roller 342 and the recovery roller 351 stop rotating after the voltage application to the coat electrode member 341 and the recovery roller 351 is stopped. Therefore, damage to the electrode roller 342 can be reduced.

<Fourth Embodiment>
A fourth embodiment will be described using FIG. 13 while referring to FIGS. It should be noted that the present embodiment is the same as the first embodiment except for the control in section B of the flowchart of FIG. 9 of the first embodiment. For this reason, the same reference numerals are used for the same configurations as in the first embodiment, and the description and illustration are omitted or simplified, and the following description focuses on the points different from the first embodiment.

A control flow of the operation of separating and extracting the liquid developer in this embodiment will be described with reference to FIG. 9 and FIG. As shown in FIG. 9, when the separation and extraction of the carrier liquid from inside the separation/extraction device 34 is completed (S29 in FIG. 9), the electromagnetic valves 45 and 47 are closed (S30 in FIG. 9).

Next, the supply of the liquid developer by the pump 34c is stopped (S31-C). The timing of stopping the supply (stopping the driving of the pump 34c) is, for example, 100 msec after the solenoid valves 45 and 47 are closed.

Next, voltage application to the coat electrode member 341, the electrode roller 342, and the collection roller 351 is stopped (OFF), and the driving of the drive motor 205 is stopped (S32-C). That is, the voltage application to the collection roller 351 is stopped, the rotation of the electrode roller 342 and the collection roller 351 is stopped, and the voltage application to the coat electrode member 341 is stopped at the same time. The timing of stopping voltage application and stopping driving is, for example, 100 msec after stopping supply (stopping driving of pump 34c). During this time, the liquid developer last supplied from the pump 34c is separated in the gap 347, the liquid developer reaches the nip portion between the electrode roller 342 and the recovery roller 351, and the separated toner can be recovered. Time is preferred.

That is, in the present embodiment, the supply of the liquid developer by the pump 34c is stopped, and then the voltage application to the coat electrode member 341, the electrode roller 342, and the recovery roller 351 is stopped. stop spinning. As a result, while the electrode roller 342 is rotating, a voltage is applied to the coat electrode member 341 and the collection roller 351, so that the liquid developer can be separated and the separated toner can be collected. After S32-C, this control ends, and prepares for separation processing.

In this embodiment as well, after the pump 34c is stopped, voltage application to the recovery roller 351 and the coat electrode member 341 is stopped, and driving of the drive motor 205 is stopped. Ejection without being separated can be reduced. Further, in the case of the present embodiment, the rotation of the electrode roller 342 and the collection roller 351 is stopped at the same time when the voltage application to the coat electrode member 341 and the collection roller 351 is stopped. Therefore, damage to the electrode roller 342 can be reduced.

34 Separation extraction device (separation device)/34c Pump (supply unit)/205 Drive motor (drive source)/341 Coated electrode member (electrode member)/342 Electrode Roller/345 Voltage application device (voltage application means)/346b Discharge portion (carrier recovery portion)/347 Gap/351 Recovery roller/352 Blade member/C・Carrier liquid/D: Liquid developer/T: Toner

Claims (8)

A separation device for separating a toner and a carrier liquid by using an electric field from a liquid developer collected in an image forming section that forms an image using the liquid developer containing the toner and the carrier liquid,
a conductive electrode roller rotating in a predetermined direction;
an electrode member disposed with a gap from the outer surface of the electrode roller and capable of applying a voltage between the electrode roller and the electrode roller so as to generate an electric field for moving toner toward the electrode roller;
a storage unit for storing the liquid developer collected in the image forming unit;
a supply unit that supplies the liquid developer from the storage unit to the gap;
a carrier recovery unit that is provided adjacent to the electrode member downstream with respect to the rotation direction of the electrode roller and recovers the carrier liquid;
a recovery roller disposed downstream of the carrier recovery section with respect to the rotation direction of the electrode roller, and capable of applying a voltage between the electrode roller and the electrode roller so as to generate an electric field for moving toner from the electrode roller side; , and
By supplying the liquid developer from the supply unit, rotating the electrode roller and the recovery roller, applying voltage to the electrode member, and applying voltage to the recovery roller, the toner and carrier are transferred from the liquid developer. When the separation operation is completed, the supply of the liquid developer by the supply unit is stopped, the voltage application to the recovery roller is stopped, and the electrode roller and the recovery roller are separated. Stopping the rotation and stopping the application of the voltage to the electrode member;
A separation device characterized by: After stopping the application of the voltage to the recovery roller or at the same time as stopping the application of the voltage to the recovery roller, the rotation of the electrode roller and the recovery roller is stopped, and then or the electrode roller and the recovery roller are stopped. At the same time as stopping the rotation of the electrode member, stop applying the voltage to the electrode member,
The separation device according to claim 1, characterized in that: After stopping the application of the voltage to the collection roller or at the same time as stopping the application of the voltage to the collection roller, the application of the voltage to the electrode member is stopped, and then the rotation of the electrode roller and the collection roller is stopped. do,
The separation device according to claim 1, characterized in that: After stopping the voltage application to the electrode member or at the same time as stopping the voltage application to the electrode member, the voltage application to the recovery roller is stopped, and thereafter or the voltage application to the recovery roller is stopped. At the same time, the rotation of the electrode roller and the collection roller is stopped;
The separation device according to claim 1, characterized in that: Stopping the voltage application to the electrode member, stopping the voltage application to the recovery roller, and stopping the rotation of the electrode roller and the recovery roller at the same time;
The separation device according to claim 1, characterized in that: The supply unit is a pump that conveys the liquid developer,
the recovery roller is driven to rotate in contact with the electrode roller;
a drive source for driving the electrode roller;
voltage applying means for applying a voltage to the collection roller,
Stopping the pump, and then stopping the application of the voltage by the voltage applying means and stopping the driving of the driving source;
6. Separating apparatus according to any one of claims 1 to 5, characterized in that: The voltage applying means can stop applying the voltage to the electrode member and the collection roller separately.
7. Separating device according to claim 6, characterized in that: a blade member that contacts the collecting roller and collects the toner on the collecting roller,
8. Separating apparatus according to any one of claims 1 to 7, characterized in that:

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