WO2020013342A1

WO2020013342A1 - Separator

Info

Publication number: WO2020013342A1
Application number: PCT/JP2019/027833
Authority: WO
Inventors: 哲平永田; 幸寛添田; 威裕小島
Original assignee: キヤノン株式会社
Priority date: 2018-07-13
Filing date: 2019-07-09
Publication date: 2020-01-16
Also published as: JP2020012905A

Abstract

The present invention increases the efficiency with which toner and a carrier liquid are separated from a liquid developer. Provided is a separator which separates toner and a carrier liquid from a liquid developer. Specifically provided is a separator for separating, using an electric field, toner and a carrier liquid from a liquid developer containing the toner and carrier liquid, wherein the separator comprises: an electrode roller; an electrode member which is disposed such that there is a gap between the electrode member and the outer circumferential surface of the electrode roller, and in which voltage that generates an electric field for moving the toner to the electrode roller side can be applied across the electrode member and the electrode roller; a supply part which supplies the liquid developer to the aforementioned gap; a carrier recovery part which is provided adjacent to the downstream side of the electrode member in terms of the rotation direction of the electrode roller and recovers the carrier liquid; a recovery roller which is disposed further downstream than the carrier recovery part in terms of the rotation direction of the electrode roller, and in which voltage that generates an electric field for moving the toner from the electrode roller side can be applied across the recovery roller and the electrode roller; and a control unit which performs control such that the supply of the liquid developer by the supply part is stopped, then the application of voltage across the electrode member and the recovery roller is stopped, and thereafter the rotation of the electrode roller and the recovery roller is stopped. The present invention thereby increases the efficiency with which the toner and the carrier liquid are separated from the liquid developer.

Description

Separation device

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

Conventionally, an image forming apparatus that forms an image using a liquid developer containing a toner and a carrier liquid has been known. In such an image forming apparatus, the liquid developer not used in the image forming process is collected and recycled. In such a liquid developer recycling process, toner particles as a dispersoid in a liquid developer (liquid material) and a carrier liquid as a dispersion medium are separated, and the carrier liquid is reused.

For example, there has been proposed a separation device that includes an electrode roller, an electrode member, a supply unit, a carrier collection unit, and a collection roller, and separates a toner and a carrier liquid from a liquid developer using an electric field. JP-A-2006-224424).

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

Here, in the separation device described in JP-A-2006-224424, for example, when the application of the voltage to the electrode member is stopped before the supply of the liquid developer by the supply unit is stopped, the liquid development supplied to the gap is stopped. The agent may be discharged without being separated.
[Problems to be solved by the invention]
An object of the present invention is to improve the efficiency of separating a toner and a carrier liquid from a liquid developer.

FIG. 1 is a schematic configuration diagram of the image forming apparatus according to the first embodiment.

FIG. 2 is a schematic configuration diagram illustrating a transport path of the liquid developer of the image forming apparatus according to the first embodiment.

FIG. 3 is a control block diagram of the transport operation of the liquid developer of the image forming apparatus according to the first embodiment.

FIG. 4 is a flowchart showing control of the liquid developer transport operation of the image forming apparatus according to the first embodiment.

FIG. 5 is a perspective view of the separation and extraction device according to the first embodiment.

FIG. 6 is a perspective view of a part of the separation and extraction device according to the first embodiment.

FIG. 7 is a sectional view showing a part of the separation and extraction device according to the first embodiment.

FIG. 8 is an enlarged view of a portion A in FIG.

FIG. 9 is a flowchart showing the control of the operation of separating and extracting the liquid developer according to the first embodiment.

FIG. 10 is a cross-sectional view illustrating a flow of toner by extracting a part of the separation and extraction device according to the first embodiment.

FIG. 11 is a flowchart showing the control of the portion corresponding to the section B in FIG. 9 in the control of the operation of separating and extracting the liquid developer according to the second embodiment.

<First embodiment>
The first embodiment will be described with reference to FIGS. First, a schematic configuration of the image forming apparatus according to the present embodiment will be described with reference to FIG.
[Image forming apparatus]

The image forming apparatus 100 of the present embodiment is an electrophotographic digital printer that forms a toner image on a recording material (paper, sheet material such as an OHP sheet). The image forming apparatus 100 operates based on an image signal, transfers the toner image formed by the image forming unit 12 to a sheet S as a recording material sequentially conveyed from the

cassettes

11a and 11b, and then fixes the toner image. I have an image. The image signal is sent to the image forming apparatus 100 from an external terminal such as a scanner or a personal computer (not shown).

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

The liquid developer D is generated by mixing and dispersing the toner T with the carrier liquid C at a predetermined ratio in a 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 (collection 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 each tank according to the mixing 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), mixes the supplied carrier liquid C and the toner T by stirring, 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 carrier by a coating roller 17 in a supply section 16a of the developing device 16 and used for development. You. The developing roller 18 carries and transports the liquid developer on the surface, and develops the electrostatic latent image formed on the photosensitive drum 13 (on the image carrier) with toner. The carrier liquid C and the toner T remaining on the developing roller 18 after the development are collected in a collecting section 16b 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 performed using electric fields.

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

The sheets S stored in the

cassettes

11a and 11b are conveyed toward the registration conveying unit 23 by the

feeding units

22a and 22b including conveying rollers and the like. The resist conveyance unit 23 conveys the sheet S to a nip between the intermediate transfer roller 20 and the transfer roller 21 at 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 on 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 fixed toner image is fixed. The sheet S on which the toner image has been fixed is discharged out of the apparatus, 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 remaining toner T and carrier liquid C, respectively.
[Transport of liquid developer]

Next, transport of the liquid developer D in the present embodiment will be described with reference to FIGS. First, as described above, 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 is used to separate the toner and the carrier liquid by the separation and extraction device 34 as a separation device. Separate and reuse the carrier liquid. The developer remaining on the developing roller 18 after the development and collected in the collection section 16b of the developing device 16 is returned to the mixer 31, but may be conveyed to the separation and extraction device 34.

As will be described in detail later, the separation / extraction device 34 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, and separates them. The waste liquid W is collected in the waste liquid collection container 35.

する More specifically,

Electromagnetic valves

41 and 42 are provided in the transport pipes from the carrier tank 32 and the toner tank 33 to the mixer 31, respectively, to adjust the supply amounts of the carrier liquid C and the toner T to the mixer 31. From the mixer 31, a liquid developer D required for development is supplied to the developing device 16 using a pump 44.

現像 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 is not used for development or the like and is 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 and extraction device 34 by

pumps

48, 49, and 50, respectively.

(4) The reusable carrier liquid separated by the separation and 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 separation / extraction device 34 is appropriately conveyed to the waste liquid collection container 35 by the electromagnetic valve 47 provided on the transport pipe by its own weight.

The transfer of the liquid developer or the like may be carried out by using a self-weight without using a pump, for example, in a case where the liquid developer can be conveyed by its own weight, instead of using a pump.

As shown in FIG. 3, the

pumps

43, 44, 48, 49, 50 and the

electromagnetic valves

41, 42, 45, 47 are controlled by a CPU 200 as a control unit via a pump driver 201 and an electromagnetic valve driver 202, respectively. Is controlled. The pump 34c, which will be described later, is controlled by the CPU 200 via the pump driver 201, similarly to 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 described below.

(4) Such a transport operation of the liquid developer will be described with reference to FIGS. First, as shown in FIGS. 2 and 3, the developing device 16 is provided with an agent amount detecting device 160, and the amount of liquid developer in the developing device 16 is detected by the agent amount detecting device 160. 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 unit and a light receiving unit, and irradiates light from the light emitting unit to a portion of the mixer 31 through which the liquid passes, and receives light transmitted through this portion by the light receiving unit. . Since the amount of light received by the light receiving portion changes according to 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.

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

Next, the concentration of the solid component in the mixer 31 is detected by the solid component concentration detecting device 310 (S4). When the concentration of the solid component in the mixer 31 is out of a predetermined range (for example, 10 ± 0.5%), it is determined whether or not 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 electromagnetic valve 41 is opened, and the carrier liquid is supplied from the carrier tank 32 into the mixer 31 (S6). On the other hand, if the concentration of the solid component is not 10.5% or more, that is, 9.5% or less, the electromagnetic valve 42 is opened and the toner is supplied 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 component in the mixer 31 falls within a predetermined range, the pump 44 is driven as necessary to supply the liquid developer whose concentration has been adjusted from the mixer 31 to the developing device 16 (S8). Then, at the same time as the image formation is started (S9), the driving of each of the

pumps

43, 48, 49, 50 is also started (S10), and the driving of the separation / extraction device 34 is also started (S11).
[Separation and extraction device]

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

The liquid developer collected by the image forming unit 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 container 346 as indicated by arrows in FIGS. You. Then, the liquid is supplied to the buffer container 348 in the liquid container 346. In the present embodiment, the buffer container 348 is provided in the separation and extraction device 34, but may be provided as a single container. The liquid developer supplied to the buffer container 348 is transported by the pump 34c as a supply unit, and passes through the filter 34d.

6 and 7, the liquid developer that has passed through the filter 34d is supplied to a supply tray 346a, and is conveyed by a pump 34c into a gap 347 between an electrode roller 342 and a coat electrode member 341 described later. (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 347a (FIG. 7) of the gap 347 in the rotation direction of the electrode roller 342 via the supply tray 346a.

The supply unit may be a supply roller disposed in contact with or close to the electrode roller 342 other than the pump. For example, instead of a supply tray, a storage tank that can store the liquid developer is arranged like a tub, and the liquid developer collected as described above is stored in this storage tank. Then, the supply roller is arranged so as to be in 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 to the surface 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 the case of this configuration, the supply roller may be driven separately from the electrode roller 342, or may be driven by the same drive source as the electrode roller 342. Further, the supply roller may be brought into contact with the electrode roller 342 to be driven and rotated by the electrode roller 342. Further, the member for scraping 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 may be used. Further, in this embodiment, the liquid developer is transported by the pump 34c, but may be transported with the rotation of the electrode roller 342.

In the case of the present embodiment, as will be described in detail later, the liquid developer that is supplied to the supply tray 346a and sent into the gap 347 by the pump 34c is separated into the toner and the carrier liquid in the separation and extraction device 34. Then, the extracted toner is sent to the waste liquid collecting container 35, and the extracted carrier liquid is transferred to the carrier tank 32.

Next, the configuration of the separation and extraction of the toner and the carrier liquid in the separation and extraction device 34 will be described in detail. As shown in FIGS. 6 and 7, a coating electrode member 341 as an electrode member, an electrode roller 342 as a conductive roller, a toner collecting device 350, and the like are arranged in the liquid container 346. The liquid storage container 346 is a container capable of storing a liquid developer, and includes a supply tray 346a described above and a discharge unit 346b serving as a carrier recovery unit that discharges a reusable carrier liquid as described later. And a collection unit 354 for collecting the developer that has become waste liquid.

The electrode roller 342 is a conductive roller in which a urethane rubber elastic layer is integrally formed on a surface of a metal core having an outer diameter of φ40 mm made of, for example, solid stainless steel. As shown in FIG. 3, the driving of the electrode roller 342 is input from the outside by a driving motor 205 as a driving source, and the electrode roller 342 rotates in a predetermined direction (the direction of the arrow in FIGS. 6 and 7). In the present embodiment, the rotation speed of the drive motor 205 is set to 2000 rpm. Then, the electrode roller 342 rotates at a rotation speed of, for example, 400 rpm by reducing the rotation of the drive motor 205 by a speed reducer. Note that the voltage application device 345 is controlled by the CPU 200 via the high voltage driver 204, and the drive motor 205 is controlled by the CPU 200 via the motor driver 203.

The coated electrode member 341 is disposed with a part of the outer surface of the electrode roller 342 via a gap 347, as shown in FIGS. A supply tray 346a is connected to an upstream end 347a of the gap 347 in the rotation direction of the electrode roller 342. Then, the liquid developer put in the supply tray 346a as described above is supplied from the upstream end 347a into the gap 347 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 transported in the gap 347 to the downstream side in the rotation direction with the rotation of the electrode roller 342. .

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

The transport pipe 346c is also connected to a path for returning the discharged liquid developer to the separation and extraction device 34 again. The discharge unit 346b is provided with a carrier liquid concentration detecting device 34a, which detects the toner concentration in the carrier liquid of the liquid developer sent into the discharge unit 346b. The configuration of the carrier liquid concentration detecting device 34a is the same as that of the above-described solid component concentration detecting device 310. When the toner concentration of the liquid developer sent to the discharge unit 346b is higher than a predetermined value (for example, 0.02%), the liquid developer is returned to the separation / extraction device 34 again to separate the toner and the carrier liquid. To do.

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

As described above, in the coat electrode member 341 arranged via the electrode roller 342 and the gap 347, at least the surface of the portion 341x through which the liquid passes is formed of a conductive material. The coated electrode member 341 is formed 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 the portion 341x facing the electrode roller 342 has a predetermined distance (ie, the gap 347) from the surface of the electrode roller 342. ). The predetermined distance is, for example, 0.2 mm.

(3) As shown in FIG. 3, the coat electrode member 341 and the electrode roller 342 are connected to a voltage application device 345 as voltage application means. Then, a voltage can be applied between the coat electrode member 341 and the electrode roller 342 by the voltage application device 345 so that an electric field for moving the toner toward the electrode roller 342 (electrode roller side) is generated. That is, a voltage is applied to the gap 347 so that an electric field is generated such that the toner is attracted to the electrode roller 342.

In the present embodiment, since the toner is negatively charged by the charge control agent, for example, −300 V is applied to the electrode roller 342 and −1000 V is applied to the coat electrode member 341. Then, the toner in the liquid developer passing through the gap 347 moves from the coat electrode member 341 to the electrode roller 342. As a result, while the liquid developer passes 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 part 346b connected to the downstream end 347b of the gap 347, and is sent to the carrier tank 32 as a collection container as described above.

The toner collecting device 350 is located downstream of the coat electrode member 341 with respect to the rotation direction of the electrode roller 342, and collects the toner carried on the electrode roller 342. The toner collecting device 350 includes a collecting roller 351, a voltage applying device 345 as a collecting voltage applying unit, and a blade member 352 as a scraping member.

The recovery roller 351 is a conductive roller formed of, for example, solid stainless steel and having an outer diameter of φ20 mm, and is disposed so as to contact the electrode roller 342. Then, the collection roller 351 comes into contact with the electrode roller 342 and rotates in the direction indicated by the arrow in FIGS. The rotation speed of the collection roller 351 is, for example, 800 rpm. That is, the collection roller 351 is located downstream of the discharge portion 346b and upstream of the coat electrode member 341 with respect to the rotation direction of the electrode roller 342, and contacts the electrode roller 342 and faces the electrode roller 342. Rotate forward in position with each other. In the present embodiment, the collection roller 351 rotates following the electrode roller 342. However, a configuration may be adopted in which a drive motor inputs driving from the outside and rotates.

The electrode roller 342 and the collection roller 351 are arranged substantially in parallel with each other, and both ends in the direction of the rotation axis are rotatably supported by a frame constituting the liquid container 346. Further, biasing mechanisms such as springs are provided at both ends of the collection roller 351. The collection roller 351 is urged toward the electrode roller 342 by an urging mechanism, and elastically deforms the electrode roller 342. The pressing force of the urging mechanism on the collection roller 351 against the electrode roller 342 is, for example, 3 kgf (29.4 N).

The coating electrode member 341 and the collection roller 351 are positioned with reference to the electrode roller 342, and the electrode roller 342 is used as a position reference for these members.

As shown in FIG. 3, the voltage applying device 345 is connected to the electrode roller 342 and the collecting roller 351, and an electric field that causes toner to move to the collecting roller is generated between the collecting roller 351 and the electrode roller 342. Voltage as described above. In the present embodiment, the voltage application device connected to the electrode roller 342 and the collection roller 351 and the voltage application device connected to the electrode roller 342 and the coat electrode member 341 are common, but may be different. In the present embodiment, for example, −300 V is applied to the electrode roller 342, and −200 V is applied to the collection roller 351. Then, the toner carried on the electrode roller 342 and conveyed to the collection roller 351 moves from the electrode roller 342 to the collection roller 351.

The blade member 352 comes into contact with the collection roller 351 to scrape off the toner on the collection roller. The blade member 352 is arranged downstream of the position where the electrode roller 342 and the collection roller 351 are in contact with each other in the rotation direction of the collection roller 351 so as to contact the collection roller 351 in the counter direction. The blade member 352 is urged so that the front end 352 a contacts the surface of the collection roller 351. Note that the counter direction is a direction in which the direction of the tip of the blade member 352 that contacts the collection roller 351 is opposite to the tangential direction along the rotation direction of the collection roller 351. Further, the blade member 352 is a plate-like member extending along the longitudinal direction (the rotation axis direction) of the collection roller 351 and is made of, for example, stainless steel.

As described above, the toner that has moved from the electrode roller 342 to the collection roller 351 is scraped off by the blade member 352 and sent to the collection unit 354 as a toner collection unit. The toner collected by the collection unit 354 is sent to the waste liquid collection container 35 as described above. 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 may be used.
[Control flow of liquid developer separation / extraction operation]

Next, a control flow of the operation of separating and extracting the liquid developer according to the present embodiment configured as described above will be described with reference to FIGS. 9 and 10. First, by driving the

pumps

48, 49, and 50, the developer collected by the drum cleaner 19, the intermediate transfer roller cleaner 26, and the transfer roller cleaner 27 is transported to the separation and extraction device 34. Then, after a predetermined amount of the developer is sent to the separation and extraction device 34, the

pumps

48, 49, and 50 are stopped (S21).

Next, the supply of the liquid developer by the pump 34c is started (S22). The timing of the start of supply (start of driving of the pump 34c) is, for example, 100 msec after the stop of the

pumps

48, 49, and 50. The drive of the pump 34c may be started at the same time as the stop of the

pumps

48, 49, and 50, or may be before the stop.

Next, the drive of the drive motor 205 is started to rotate the electrode roller 342 and the collection roller 351 (S23). The timing of starting the driving of the driving motor 205 is, for example, 100 msec after the driving of the pump 34c is started. After the

pumps

48, 49, and 50 are stopped, the drive of the drive motor 205 may be started first, and then, or simultaneously with the start of the drive of the drive motor 205, the drive of the pump 34c may be started.

Next, the application of the voltage by the voltage application device 345 is started (ON), and the application of the voltage to the coat electrode member 341 and the collection roller 351 is started (S24). The timing of voltage application is, for example, 100 msec after the start of supply. This time is preferably the time required for the liquid developer to reach the nip between the electrode roller 342 and the collection roller 351 from the pump 34c.

That is, in the present embodiment, after the rotation of the electrode roller 342 and the collection roller 351 is started, the pump 34c starts supplying the liquid developer, and thereafter, the application of the voltage between the coat electrode member 341 and the collection roller 351 is started. . Thus, the liquid developer is supplied to the gap 347 by the pump 34c while the electrode roller 342 and the collection roller 351 are rotated, and the liquid developer is transported with the rotation of the electrode roller 342.

Then, at the timing when the liquid developer almost reaches the nip portion between the electrode roller 342 and the collection roller 351, the application of the voltage to the coat electrode member 341 and the collection roller 351 is started. At this time, in the present embodiment, a voltage is also applied to the electrode roller 342. As a result, an electric field that causes the toner to move to the electrode roller 342 between the coat electrode member 341 and the electrode roller 342 and an electric field that causes the toner to move to the collection roller side between the collection roller 351 and the electrode roller 342 are generated. Is applied with a voltage. 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 coat 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 generates an electric repulsive force from the coat electrode member 341. receive. As a result, the toner T is electrically urged toward the electrode roller 342 side. At this time, there is a toner T layer on the electrode roller 342 side, and there is a layer of the carrier liquid C 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.

As described above, the toner T in the liquid developer conveyed to the collecting roller 351 by the electrode roller 342 through the gap 347 is electrically attracted to the collecting roller 351 and receives an electric repulsive force from 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. At this time, the carrier liquid C is divided into the electrode roller 342 side and the collection roller 351 side at a predetermined ratio, and the carrier liquid C layer (the chain line in FIG. Due to the rotation, it is transported to the upstream end 347a of the gap 347. That is, the carrier liquid C divided on the side of the electrode roller 342 with respect to the collection roller 351 is returned to the entrance of the gap 347. Then, it merges with the liquid developer supplied from the supply tray 346a, and is again conveyed to the gap 347.

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

The toner electrically attached to the collection roller 351 is scraped off by the blade member 352. Here, the solenoid valve 47 is opened (S25). As a result, the toner scraped off by the blade member 352 falls under its own weight and is collected by the collection unit 354 into the waste liquid collection container 35. The toner may be discarded or reused.

The carrier liquid discharged from the downstream end 347b of the gap 347 to the discharge section 346b has a toner concentration detected by the carrier liquid concentration detecting device 34a, and the detected toner concentration is a predetermined value (for example, 0.02%). It is determined whether or not the following is true (S26). If the toner concentration is equal to or lower than the predetermined value, the electromagnetic valve 45 is opened and the carrier liquid is sent to the carrier tank 32 (S27). When the separation and extraction of the carrier liquid from the separation and extraction device 34 is completed (S28), the

solenoid valves

45 and 47 are closed (S29).

Next, the supply of the liquid developer by the pump 34c is stopped (S30). The timing of stopping the supply (stopping the driving of the pump 34c) is, for example, 100 msec after the closing of the

solenoid valves

45 and 47.

Next, the application of the voltage by the voltage application device 345 is stopped (OFF), and the application of the voltage to the coat electrode member 341 and the collection roller 351 is stopped (S31). The voltage application is stopped, for example, 100 msec after the supply is stopped. This time is preferably set so that the liquid developer finally supplied from the pump 34c can be separated from the upstream end 347a to the downstream end 347b. Alternatively, it is preferable that the time is such that the liquid developer finally supplied from the pump 34c reaches the nip portion between the electrode roller 342 and the collection roller 351 and can collect the separated toner.

Next, the drive of the drive motor 205 is stopped, and the rotation of the electrode roller 342 and the collection roller 351 is stopped (S32). The timing of stopping the drive of the drive motor 205 is, for example, 100 msec after the voltage application device 345 is turned off.

Next, a predetermined amount of the residual developer is again conveyed to the separation and extraction device 34 by the

pumps

48, 49, and 50, and the next separation process is performed. Then, such an operation is repeatedly performed.

The separation and 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). The time required for one separation process is, for example, 30 seconds. In this case, it is possible to cope with a process speed of up to 800 mm / s.

In the case of the present embodiment, the supply of the liquid developer by the pump 34c is stopped, and then, the application of the voltage between the coat electrode member 341 and the collection roller 351 is stopped. Has stopped. For this reason, the liquid developer can be prevented from being discharged without being separated. Here, if the voltage application of the voltage application device 345 and the driving of the driving motor 205 are stopped before the driving of the pump 34c is stopped, the liquid developer lastly supplied to the gap 347 is not separated. May remain in the gap 347 or be discharged from the discharge portion 346b. The liquid developer remaining without being separated in the gap 347 may be discharged from the discharge portion 346b without being separated when the separation and extraction device 34 is driven next.

As described above, if the liquid developer is discharged from the discharge unit 346b without being separated, a high-purity carrier liquid may not be obtained and may not be reused, or may be returned to the separation and extraction device 34 again. Separation and extraction will be performed. Further, the carrier liquid in the tank storing the reused carrier liquid may be replaced.

On the other hand, in the case of the present embodiment, after the driving of the pump 34c is stopped, the voltage application of the voltage applying device 345 and the driving of the drive motor 205 are stopped. For this reason, the driving of the pump 34 c is stopped, and the liquid developer finally supplied to the gap 347 is subjected to an electric field in which the toner moves toward the electrode roller 342 between the coat electrode member 341 and the electrode roller 342 for a while. Is transported in the gap 347 in a state in which is formed.

As a result, the liquid developer finally supplied to the gap 347 is separated into the toner and the carrier liquid, and the carrier liquid is discharged to the discharge section 346b. On the other hand, the toner is transported to the collection roller 351 and collected by the collection roller 351. As described above, after the driving of the pump 34c is stopped, the application of the voltage by the voltage applying device 345 and the driving of the driving motor 205 are stopped, so that the liquid developer remains in the gap 347 without being separated or is discharged. It is possible to reduce discharge from the portion 346b.

In particular, if the liquid developer finally supplied to the gap 347 reaches the downstream end 347b from the upstream end 347a and stops the voltage application of the voltage application device 345 at the timing when the liquid developer is separated, the gap The liquid developer supplied last to 347 can be more reliably separated. Further, if the voltage application of the voltage applying device 345 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 collection roller 351, the toner is more reliably collected. it can.

The voltage application by the voltage application device 345 may be stopped after the driving of the pump 34c is stopped, and before the liquid developer last supplied to the gap 347 reaches the downstream end 347b. Is also good. Even in this case, while the voltage is applied, the liquid developer is separated, so that the amount of the liquid developer discharged from the discharge unit 346b without being separated can be reduced. Further, the timing of stopping the application of the voltage by the voltage applying device 345 may be before reaching the nip portion between the electrode roller 342 and the collection roller 351. Even in this case, since the separated toner is collected by the collection roller 351 even a little, the toner not collected by the collection roller 351 can be reduced.

In addition, in the case of the present embodiment, the rotation of the electrode roller 342 and the collection roller 351 is stopped after the application of the voltage between the coat electrode member 341 and the collection roller 351 is stopped. Therefore, damage to the electrode roller 342 can be reduced. That is, when a voltage is applied to the coat electrode member 341 in a state where the rotation of the electrode roller 342 is stopped, the voltage is continuously applied to the same portion of the electrode roller 342, and the electrode roller 342 may be damaged. . On the other hand, in the case of the present embodiment, since the rotation of the electrode roller 342 is stopped after the application of the voltage of the coat electrode member 341 is stopped, the voltage is continuously applied to the same portion of the electrode roller 342. Thus, damage to the electrode roller 342 can be reduced.

In the above-described embodiment, an example has been described in which a toner is used as a dispersoid and a carrier liquid is used as a dispersion medium. However, 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>

２A second embodiment will be described with reference to FIGS. 2, 3, 5 to 9 and FIG. This embodiment is the same as the first embodiment except for the control in the section B of the flowchart of FIG. 9 of the first embodiment. Therefore, the same components as those of the first embodiment are denoted by the same reference numerals, and the description and illustration are omitted or simplified. Hereinafter, the description will be focused on the points different from the first embodiment.

制御 A control flow of the operation of separating and extracting the liquid developer in the present 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 the inside of the separation and extraction device 34 is completed (S28 in FIG. 9), the

solenoid valves

45 and 47 are closed (S29 in FIG. 9).

Next, the supply of the liquid developer by the pump 34c is stopped (S30-A). The timing of stopping the supply (stopping the driving of the pump 34c) is, for example, 100 msec after the closing of the

solenoid valves

45 and 47.

Next, the application of the voltage by the voltage application device 345 is stopped (OFF), and the driving of the drive motor 205 is stopped (S31-A). That is, the rotation of the electrode roller 342 and the collection roller 351 is stopped at the same time as the application of the voltage between the coat electrode member 341 and the collection roller 351 is stopped. The timing of the voltage application stop and the drive stop is, for example, 100 msec after the supply stop (the drive stop of the pump 34c). During this time, the liquid developer finally supplied from the pump 34c is separated in the gap 347, and the liquid developer reaches the nip portion between the electrode roller 342 and the collection roller 351 to collect the separated toner. Preferably, it is time.

That is, in the present embodiment, the supply of the liquid developer by the pump 34c is stopped, and thereafter, the application of the voltage between the coat electrode member 341 and the collection roller 351 is stopped, and simultaneously, the rotation of the electrode roller 342 and the collection roller 351 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 S31-A, this control ends, and next, preparations are made for separation processing.

Also in the case of the present embodiment, after the supply of the liquid developer by the pump 34c is stopped, the application of the voltage by the voltage applying device 345 and the driving of the drive motor 205 are stopped. For this reason, the liquid developer can be prevented from being discharged without being separated. 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 as the application of the voltage between the coat electrode member 341 and the collection roller 351 is stopped. Therefore, damage to the electrode roller 342 can be reduced.
In the present embodiment, a case where a conventionally used liquid developer is used as the liquid developer used in the image forming apparatus 100 has been described as an example, but the present invention is not limited to this. For example, the liquid developer used in the image forming apparatus 100 may be an ultraviolet-curable liquid developer that is cured by ultraviolet light.

According to the present invention, there is provided a separation device for separating a toner and a carrier liquid from a liquid developer, which is particularly suitable for an image forming apparatus.

The present invention is not limited to the above-described embodiment, and various changes and modifications can be made without departing from the spirit and scope of the present invention. Therefore, the following claims are appended to make the scope of the present invention public.

This application claims the priority of Japanese Patent Application No. 2018-133595 filed on Jul. 13, 2018, the entire contents of which are incorporated herein by reference.

Claims

Using an electric field, a separation device for separating the toner and the carrier liquid from the liquid developer including the toner and the carrier liquid,
An electrode roller,
An electrode member that is disposed with a gap between the outer peripheral surface of the electrode roller and the electrode roller and that can apply a voltage such that an electric field that causes toner to move toward the electrode roller is generated between the electrode member and the electrode member.
A supply unit for supplying a liquid developer to the gap,
With respect to the rotation direction of the electrode roller, provided adjacent to the downstream side of the electrode member, a carrier recovery unit that recovers a carrier liquid,
With respect to the rotation direction of the electrode roller, a collection roller that is disposed downstream of the carrier collection unit and is capable of applying a voltage such that an electric field in which toner moves from the electrode roller side is generated between the collection roller and the electrode roller. ,
A control unit that stops the supply of the liquid developer by the supply unit, and then stops applying the voltage of the electrode member and the collection roller, and then controls the rotation of the electrode roller and the collection roller to stop. A separation device comprising:
The separation device according to claim 1, wherein
The recovery roller is driven to rotate in contact with the electrode roller,
A drive source for driving the electrode roller;
A voltage application unit that applies a voltage to the electrode member and the collection roller,
The separation unit controls the control unit to stop the supply of the liquid developer by the supply unit, and then stop the drive of the drive source after stopping the application of the voltage by the voltage application unit.
The separation device according to claim 2, wherein
The supply unit is a pump that conveys the liquid developer,
The separation unit controls the control unit to stop the pump, and then stop applying the voltage by the voltage applying unit and then stop driving the driving source.
The separation device according to any one of claims 1 to 3, wherein
A separation device including a blade member that contacts the collection roller and collects the toner on the collection roller.
The separation device according to any one of claims 1 to 4, wherein
The separating device, wherein the liquid developer is an ultraviolet-curable liquid developer that is cured by ultraviolet light.
Using an electric field, a separation device for separating the toner and the carrier liquid from the liquid developer including the toner and the carrier liquid,
An electrode roller,
An electrode member that is disposed with a gap between the outer peripheral surface of the electrode roller and the electrode roller and that can apply a voltage such that an electric field that causes toner to move toward the electrode roller is generated between the electrode member and the electrode member.
A supply unit for supplying a liquid developer to the gap,
With respect to the rotation direction of the electrode roller, provided adjacent to the downstream side of the electrode member, a carrier recovery unit that recovers a carrier liquid,
With respect to the rotation direction of the electrode roller, a collection roller that is disposed downstream of the carrier collection unit and is capable of applying a voltage such that an electric field in which toner moves from the electrode roller side is generated between the collection roller and the electrode roller. ,
A control unit that stops the supply of the liquid developer by the supply unit, and then controls the stop of the rotation of the electrode roller and the collection roller simultaneously with the stop of the application of the voltage of the electrode member and the collection roller, A separation device comprising:
The separation device according to claim 6, wherein
The recovery roller is driven to rotate in contact with the electrode roller,
A drive source for driving the electrode roller;
A voltage application unit that applies a voltage to the electrode member and the collection roller,
The separation unit controls the control unit to stop the supply of the liquid developer by the supply unit, and then stop the driving of the driving source simultaneously with the stop of the application of the voltage by the voltage application unit.
The separation device according to claim 7, wherein
The supply unit is a pump that conveys the liquid developer,
The separation unit controls the control unit to stop the pump, and then stop the driving of the driving source simultaneously with stopping the application of the voltage by the voltage applying unit.
A separation device according to any one of claims 6 to 8, wherein
A separation device including a blade member that contacts the collection roller and collects the toner on the collection roller.
The separation device according to any one of claims 6 to 9, wherein
The separating device, wherein the liquid developer is an ultraviolet-curable liquid developer that is cured by ultraviolet light.