JP2015184370A - Discharge device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge device that discharges, to a storage part, a liquid developer recovered from a developing member that develops a latent image into a toner image by using the liquid developer stored in the storage part, and discharge the liquid developer having a large proportion of reusable toner to the storage part.SOLUTION: A discharge device 130 includes: an electric field forming unit 134 that is arranged on a recovery path 133 of a liquid developer G, which connects a storage part 100 that stores the liquid developer G containing a toner T and a developing member 122 that develops a latent image formed on an image carrier 12 into a toner image with the liquid developer G stored in the storage part 100, and forms an electric field on the liquid developer G recovered from the developing member 122; and a discharge unit 132A2 that discharges a reusable toner T to be conveyed from the electric field forming unit 134 to the storage part 100.

Description

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

  Patent Document 1 describes a cleaning device provided with a first electrode and a second electrode, which removes a liquid developer remaining on an image carrier of a wet image forming apparatus. In Patent Document 1, an electric field is formed between the first electrode and the second electrode, and the charged toner contained in the liquid developer is moved from the first electrode to the second electrode. A configuration is disclosed.

  In Patent Document 2, an electrostatic image formed on the surface of a rotating photosensitive drum is developed with a developer filled in a developing device to form a toner image, and the toner image is placed on a predetermined transfer material. A configuration of an image forming apparatus is disclosed in which the toner remaining on the surface of the photosensitive drum after the toner image is transferred is collected by a cleaning device, and the collected toner is recycled into the developing device.

JP 2007-114362 A JP 2001-125455 A

  An object of the present invention is to reusable toner in a discharge device for discharging a liquid developer collected from a developing member that develops a latent image as a toner image using a liquid developer stored in a storage unit to the storage unit. Is discharged to the liquid developer container.

  The discharge device according to claim 1 of the present invention develops, as a toner image, a storage portion that stores a liquid developer containing toner, and a latent image formed on the image carrier with the liquid developer stored in the storage portion. An electric field forming unit that forms an electric field on the liquid developer collected from the developing member, and a reusable toner conveyed from the electric field forming unit. And a discharge part that discharges the liquid into the housing part.

A discharge device according to a second aspect of the present invention is the discharge device according to the first aspect, wherein the electric field forming portion includes a counter electrode, and a voltage is applied to the counter electrode to apply the counter electrode. Collect and sort reusable toner on one of the electrodes,
The discharge unit is configured to convey reusable polarity toner from one electrode constituting the counter electrode.

  A discharge device according to a third aspect of the present invention is the discharge device according to the first aspect, wherein the electric field forming portion includes a counter electrode, and an AC voltage is applied to the counter electrode to apply a liquid developer. The toner contained in the toner is made a reusable toner.

  The discharge device according to claim 4 of the present invention is the discharge device according to claim 1, wherein the electric field forming portion includes a counter electrode, and an AC voltage is superimposed on a DC voltage on the counter electrode. A voltage is applied to collect and sort toners of a size and polarity that can be reused for one electrode constituting the counter electrode, and the discharge unit recycles from one electrode constituting the counter electrode. A toner having a usable size and polarity is conveyed.

  The discharge device according to claim 5 of the present invention is the discharge device according to any one of claims 1 to 4, wherein the electric field forming portion includes a counter electrode, and is disposed between the counter electrodes. And a member in which an opening or a gap is formed so that toner of a predetermined size or less can pass in a direction in which the counter electrode faces.

  The discharge device according to claim 6 of the present invention is the discharge device according to claim 2, wherein one electrode constituting the counter electrode has an opening or a passage through which toner of a predetermined size or less can pass. The electric field forming unit applies a DC voltage to the counter electrode so that the polarity of the member becomes a reusable toner polarity, and constitutes the counter electrode. Toner having a polarity larger than that determined for the electrode of the first electrode or toner having a different polarity from the reusable toner is collected, and the toner having a reusable size and polarity of the second electrode is collected and sorted. Is configured such that toner of a size and polarity that can be reused is conveyed from one electrode constituting the counter electrode.

  A discharge device according to a seventh aspect of the present invention is the discharge device according to the first to sixth aspects, wherein the liquid developer includes a carrier liquid, and a difference in SP value between the toner and the carrier liquid is It has a relationship of 1.5 or more and 7.0 or less.

According to an eighth aspect of the present invention, there is provided a developing device for accommodating a liquid developer containing toner, a developing member for developing a latent image formed on the image holding member as a toner image with the liquid developer, and the development. The discharge device according to claim 1, wherein the liquid developer is collected from the member and the reusable toner is discharged, and a storage unit that stores the reusable toner discharged from the discharge device. ,
It has.

  An image forming apparatus according to a ninth aspect of the present invention includes an image carrier, an exposure device that exposes the image carrier to form a latent image, a developing device according to the eighth aspect, and development on the image carrier. A transfer device that transfers the toner image transferred onto the medium, and a fixing device that fixes the toner image transferred onto the medium onto the medium.

  According to the discharge device of the first aspect of the present invention, the liquid developer having a large proportion of reusable toner is discharged to the storage unit as compared with the discharge device that does not include the electric field forming unit and the discharge unit of this configuration. Is done.

  According to the discharge device of the second aspect of the present invention, the liquid developer having a large proportion of reusable polarity toner is discharged to the storage unit as compared with the discharge device that does not include the electric field forming unit of this configuration. The

  According to the discharge device of the third aspect of the present invention, compared to the discharge device that does not apply an AC voltage to the counter electrode, the liquid developer having a large proportion of reusable toner is discharged to the storage unit. .

  According to the discharge device described in claim 4 of the present invention, compared to a discharge device that does not apply a voltage in which an alternating voltage is superimposed on a direct current voltage to the counter electrode, the reusable size and the ratio of polar toner A large liquid developer is discharged to the container.

  According to the discharge device of the fifth aspect of the present invention, the member in which an opening or a gap is formed so that toner having a size not more than a predetermined size between the counter electrodes can be passed in the direction in which the counter electrodes face each other is disposed. The liquid developer having a reusable size and a large proportion of the polar toner is discharged to the storage unit as compared with the discharge device without the discharge device.

  According to the discharge device of the sixth aspect of the present invention, the liquid developer having a reusable size and a large proportion of the polar toner is larger than that of the discharge device that does not include the electric field forming portion of this configuration. It is discharged to the housing part.

  According to the discharge device of the seventh aspect of the present invention, the difference in SP value between the toner and the carrier liquid is larger than the discharge device having no relationship of 1.5 or more and 7.0 or less. The liquid developer having a large toner ratio is discharged to the storage unit.

  According to the developing device of the eighth aspect of the present invention, as compared with a developing device that does not include the discharge device of this configuration, development failure caused by using a liquid developer containing toner that is not reusable is suppressed. The

  According to the image forming apparatus of the ninth aspect of the present invention, the image forming defect due to the developing defect is suppressed as compared with the image forming apparatus that does not include the discharging device of the present configuration.

1 is a schematic view (front view) of an image forming apparatus according to a first embodiment. 1A and 1B are schematic views (a step view as viewed from the front side) of a discharge device according to a first embodiment, in which FIG. 1A shows before reusable toner selection, and FIG. 2B shows reusable polarity toner. It is a figure which shows the state after a selection. FIG. 6 is a schematic diagram (a step view as seen from the front side) illustrating a discharge device according to a second embodiment, where (A) is before the toner (toner secondary particles) is loosened, and (B) is reusable. It is a figure which shows the state after the toner of a magnitude | size is loosened. FIG. 6 is a schematic diagram (a step view seen from the front side) illustrating a discharge device according to a third embodiment, where (A) is before toner (secondary particles of toner) is loosened, and (B) is reusable. FIG. 6 is a diagram illustrating a state after a toner having a size is loosened and a reusable polarity toner is selected. FIG. 9 is a schematic diagram (step view as seen from the front side) illustrating a discharge device according to a fourth embodiment, where (A) is before the toner (toner secondary particles) is loosened, and (B) is reusable. It is a figure which shows the state after the toner of a magnitude | size is loosened. FIG. 9 is a schematic diagram (a step view seen from the front side) illustrating a discharge device according to a fifth embodiment, where (A) is before toner (secondary particles of toner) is loosened, and (B) is reusable. FIG. 6 is a diagram illustrating a state after a toner having a size is loosened and a reusable polarity toner is selected. FIG. 10 is a schematic diagram (step view as viewed from the front side) illustrating a discharge device according to a sixth embodiment, where (A) is before reusable toner selection and (B) is after reusable toner selection. It is a figure which shows the state of.

≪Overview≫
Hereinafter, an example of an image forming apparatus according to an embodiment will be described with reference to the drawings. First, the overall configuration and operation of the image forming apparatus according to the first embodiment will be described. Next, the configuration and operation of the main part (discharge device) of the first embodiment will be described. Next, the configuration and operation of the second to sixth embodiments will be described. In the description of each embodiment, the liquid developer containing reusable toner used in each embodiment will be described prior to the description of the configuration of each embodiment.

<< First Embodiment >>

<Liquid developer>
The liquid developer G used in this embodiment is a liquid type developer obtained by dispersing powder toner T in a non-volatile oil O. In the present exemplary embodiment, the toner T includes, as an example, a polyester resin as a main component, and the average particle diameter is 3 to 6 μm. Nonvolatile oil O is dimethyl silicone oil as an example. Here, the non-volatile oil O is an example of a carrier liquid.

〔toner〕
In the present embodiment, the toner T is a state in which toner particles (a toner in a single particle state) are present alone without being aggregated and toner particles are present in an aggregated state. Secondary particles.

[Reusable toner]
In the present embodiment, the reusable toner T is a toner T charged to a positive polarity. The positive charge means that the charge amount of the toner T is charged positive as a whole.

[Non-volatile]
Here, the term “nonvolatile” means that the volatile content after 24 hours in an indoor environment having a flash point of 130 ° C. or higher or 150 ° C. is 8% by mass or less.

[Difference in SP value between toner and non-volatile oil]
In the present embodiment, the difference between the SP value of the toner T and the non-volatile oil O has a relationship of 1.5 or more and 7.0 or less.

[Calculation method of SP value]
The SP value is the square root of the density of the cohesive energy. In this embodiment, the SP values of the toner T and the non-volatile oil O are obtained by the following method.

  The SP value is obtained by the Van Kreveren and Hoftizer estimation method. This method calculates the SP value of the polymer in segment units based on the agglomeration energy value determined for each substituent in accordance with the hypothesis that the agglomeration energy density depends on the type and number of substituents. . Then, the cohesive energy calculated by this method is divided by the molar volume of the substance and the square root is taken as the SP value (reference: SP value basic / application and calculation method, Hideki Yamamoto, Information Organization Co., Ltd.) Published in 2005).

The SP value obtained by this method is conventionally expressed in units of cal ^1/2 / cm ^3/2 and is expressed dimensionlessly. In addition, in this specification, since the relative difference in SP value between two compounds is significant, in this specification, values obtained in accordance with the above-described practice are used and expressed in a dimensionless manner. To do. For reference, when the SP value obtained by this method is converted into SI units (J ^1/2 / m ^3/2 ), the SP value obtained by this method may be multiplied by 2046.

<Overall configuration of image forming apparatus>
Hereinafter, the overall configuration of the image forming apparatus 10 of the present embodiment will be described with reference to FIG. As shown in FIG. 1, the image forming apparatus 10 includes an image forming unit 20, a transport device 30, a fixing device 40, and a control unit 50.

  In the following description, in the drawings, the direction indicated by the arrow Z is the device height direction, and the direction indicated by the arrow X is the device width direction. In addition, a direction (indicated by Y) orthogonal to the device height direction and the device width direction is defined as the device depth direction.

(Control part)
The control unit 50 has a function of controlling the operation of each unit of the image forming apparatus 10.

[Conveyor]
The transport device 30 has a function of transporting the medium P in the transport direction (arrow A direction) at a predetermined transport speed. The conveyance device 30 includes a plurality of conveyance rolls 30A. The medium P is a continuous paper as an example.

(Image forming part)
As shown in FIG. 1, the image forming unit 20 has a function of forming a toner image using a liquid developer G containing toner T and nonvolatile oil O on a medium P transported by the transport device 30. Have. The image forming unit 20 includes an image forming unit 11 and a transfer unit 22. Here, the non-volatile oil O is an example of a carrier liquid. The transfer unit 22 is an example of a transfer device.

[Image forming unit]
The image forming unit 11 includes a photosensitive drum 12, a charging device 14, an exposure device 16, a developing device 18, and a removal blade 19. The charging device 14, the exposure device 16, the developing device 18, and the removal blade 19 are arranged around the photosensitive drum 12 in this order in the R1 direction. Here, the photosensitive drum 12 is an example of an image carrier.

<Photosensitive drum>
The photosensitive drum 12 has a function of holding a toner image developed by the developing device 18. The photosensitive drum 12 is formed in a cylindrical shape, and is driven to rotate about its own axis (in the direction of arrow R1) by a driving unit (not shown). The photosensitive drum 12 includes an aluminum base material, and a photosensitive layer (not shown) formed on the base material in this order: an undercoat layer, a charge generation layer, and a charge transport layer.

<Charging device>
The charging device 14 has a function of charging the outer peripheral surface of the photosensitive drum 12. The charging device 14 is disposed along the own axis direction (Y direction) of the photosensitive drum 12. In this embodiment, the charging device 14 is a scorotron charging device.

<Exposure equipment>
The exposure device 16 has a function of exposing the outer peripheral surface of the photosensitive drum 12 charged by the charging device 14 to form a latent image on the outer peripheral surface of the photosensitive drum 12. The exposure device 16 emits exposure light from a light emitting diode array (not shown) according to image data received from an image signal processing unit (not shown). The exposure light irradiates the outer peripheral surface of the photosensitive drum 12 charged by the charging device 14, and forms a latent image on the outer peripheral surface.

<Developing device>
The developing device 18 has a function of developing the latent image formed on the photosensitive drum 12 as a toner image with the liquid developer G. The developing device 18 is disposed along the own axis direction of the photosensitive drum 12. Further, the developing device 18 includes a storage unit 100, a supply unit 110, a developing unit 120, and a discharge device 130.

(Container)
The storage unit 100 has a function of storing the liquid developer G. The accommodating part 100 is a box-shaped member that opens upward. Then, the liquid developer G containing reusable toner is discharged from the discharge device 130 disposed above the storage unit 100 into the storage unit 100. In addition, the liquid developer G is replenished to the accommodating portion 110 from a replenishing device (not shown). The reusable toner will be described later.

(Supply section)
The supply unit 110 includes a supply roll 112, a regulating member 114, and a charging device 116.

{Supply roll}
The supply roll 112 has a function of supplying the liquid developer G to the developing roll 122 described later while rotating around its own axis (in the direction of the arrow R3). The supply roll 112 is a long and cylindrical member. A part of the supply roll 112 is immersed in the liquid developer G stored in the storage unit 100. The supply roll 112 pumps up the liquid developer G stored in the storage unit 100 while rotating around its own axis. The supply roll 112 is disposed so as to be rotatable in alignment with the developing roll 122 in the axial direction, and forms a nip portion N1 together with the developing roll 122. A voltage is applied to the supply roll 112 by a power source (not shown), and an electric field having a predetermined strength (hereinafter referred to as a supply electric field) is formed in the nip portion N 1, whereby the liquid developer G is applied to the development roll 122. It comes to supply. Here, the supply roll 112 is an example of a supply member. The developing roll 122 is an example of a developing member.

{Regulatory member}
The regulating member 114 has a function of regulating the amount of the liquid developer G on the outer peripheral surface of the supply roll 112 by removing the liquid developer G on the outer peripheral surface of the supply roll 112 rotating around its own axis. The restriction member 114 is a long and plate-like member. The regulating member 114 is disposed upstream of the nip portion N1 in the rotation direction of the supply roll 112 and downstream of the portion where the supply roll 112 exits from the liquid developer G in the storage unit 100. The supply roll 112 is in contact with the outer peripheral surface. Note that the liquid developer G removed from the outer peripheral surface of the supply roll 112 by the regulating member 114 falls and is accommodated in the accommodating portion 100.

{Charging device}
The charging device 116 has a function of charging the liquid developer G on the outer peripheral surface of the supply roll 112 to positive polarity as an example. The charging device 116 is disposed along the own axis direction (Y direction) of the supply roll 112. In addition, the charging device 116 is disposed upstream of the nip portion N1 in the rotation direction of the supply roll 112 and downstream of a portion of the supply roll 112 that contacts the regulating member 114. In the present embodiment, the charging device 116 is a scorotron charging device as an example.

(Development part)
The developing unit 120 includes a developing roll 122 and a charging device 124.

{Development roll}
The developing roll 122 has a function of developing the latent image formed on the photosensitive drum 12 as a toner image with the liquid developer G while rotating around its own axis (in the direction of the arrow R2). The developing roll 122 is a long and cylindrical member. The developing roll 122 is disposed along the own axis direction of the photosensitive drum 12. The developing roll 122 forms a nip portion N2 with the photosensitive drum 12. A voltage is applied to the developing roll 122 by a power source (not shown), and an electric field having a predetermined strength (hereinafter referred to as a developing electric field) is formed in the nip portion N2, thereby forming a latent image formed on the photosensitive drum 12. The image is developed as a toner image by the liquid developer G.

{Charging device}
The charging device 124 has a function of charging the liquid developer G on the outer peripheral surface of the developing roll 122 to positive polarity as an example. The charging device 124 is disposed along the own axis direction (Y direction) of the developing roll 122. Further, the charging device 124 is disposed upstream of the nip portion N2 and downstream of the nip portion N1 in the rotation direction of the developing roll 122. In the present embodiment, the charging device 124 is a scorotron charging device as an example.

(Discharge device)
The discharge device 130 collects the liquid developer G remaining on the developing roll 122 without being consumed on the outer peripheral surface of the photosensitive drum 12, and reusable toner T from the collected liquid developer G into the storage unit 100. Has the function of discharging. In other words, the discharge device 130 has a function of collecting the liquid developer G from the developing roll 122 and discharging it to the storage unit 100. The discharging device 130 is disposed upstream of the nip portion N1 and downstream of the nip portion N2 in the rotation direction of the developing roller 122, and is disposed in contact with the outer peripheral surface of the developing roller 122. Since the discharge device 130 is a main part of the present embodiment, the discharge device 130 will be described later.

<Removal blade>
The removal blade 19 remains on the outer peripheral surface of the photosensitive drum 12 without being primarily transferred after the toner image developed on the outer peripheral surface of the photosensitive drum 12 passes through a primary transfer position X1 described later together with the photosensitive drum 12. The liquid developer G is removed. The removal blade 19 includes a blade.

[Transfer unit]
The transfer unit 22 has a function of primarily transferring the toner image developed on the outer peripheral surface of the photosensitive drum 12 to the transfer roll 24 and secondarily transferring the toner image primarily transferred to the transfer roll 24 to the medium P. The transfer unit 22 includes a transfer roll 24 and a backup roll 26.

<Transfer roll>
The transfer roll 24 is in contact with the photosensitive drum 12 at the upstream side of the charging device 14 in the rotation direction of the photosensitive drum 12 and the downstream side of the developing device 18 (primary transfer position X1), and is rotated around its own axis. (In the direction of arrow R4). The transfer unit 22 primarily transfers the toner image developed on the outer peripheral surface of the photosensitive drum 12 to the transfer roll 24 at the primary transfer position X1. The oil O is transferred to the transfer roll 24 along with the primary transfer of the toner image. A primary transfer voltage is applied to the primary transfer position X1 by a power source (not shown).

<Backup roll>
The backup roll 26 is pressed against the transfer roll 24 by sandwiching the medium P at a portion (secondary transfer position X2) different from the primary transfer position X1 in the transfer roll 24, and driven rotation about its own axis (in the direction of arrow R4). It is supposed to be. The transfer unit 22 secondarily transfers the toner image primarily transferred to the transfer roll 24 to the medium P at the secondary transfer position X2. Further, oil O is transferred to the medium P along with the secondary transfer of the toner image. A secondary transfer voltage is applied to the secondary transfer position X2 by a power source (not shown).

[Fixing device]
The fixing device 40 has a function of fixing the toner image secondarily transferred to the medium P as an image on the medium P. The fixing device 40 is disposed downstream of the secondary transfer position X2 in the conveyance direction (arrow A direction) of the medium P. The fixing device 40 includes a fixing roll 42, a halogen heater 44, and a pressure roll 46.

  The fixing roll 42 is formed in a cylindrical shape. A halogen heater 44 is disposed inside the fixing roll 42. The halogen heater 44 heats the fixing roll 42 to a temperature equal to or higher than the toner melting temperature of the toner T. The fixing roll 42 is driven by a driving source (not shown) and rotates around its own axis.

  The pressure roll 46 presses the fixing roll 42 with the medium P interposed therebetween, and is driven to rotate about its own axis (in the direction of the arrow R4). Along with this, the pressure roll 46 is supported by the fixing roll 42 and pressurizes the medium P. The fixing device 40 heats and pressurizes the toner image secondarily transferred onto the medium P, and fixes the toner image on the medium P as an image.

<Operation of Image Forming Apparatus>
Hereinafter, the operation of the image forming apparatus 10 of the present embodiment will be described with reference to FIG.

  Upon receiving the image formation command, the control unit 50 operates the transport device 30, the image forming unit 20, and the fixing device 40.

  In the image forming unit 11 constituting the image forming unit 20, the photosensitive drum 12 is rotated around its own axis, and the outer peripheral surface of the photosensitive drum 12 is charged by the charging device 14.

  Next, the outer peripheral surface of the charged photosensitive drum 12 is exposed by the exposure device 16 to form a latent image (not shown).

  Next, the latent image formed on the outer peripheral surface of the photosensitive drum 12 is developed as a toner image by the developing device 18.

  Next, the toner image developed by the developing device 18 reaches the primary transfer position X1 by the rotation of the photosensitive drum 12, and is primarily transferred to the transfer roll 24 by the primary transfer voltage. Along with this, the non-volatile oil O is also transferred to the transfer roll 24 together with the toner T constituting the toner image.

  Further, after the photosensitive drum 12 has passed the primary transfer position X1, the liquid developer G on the outer peripheral surface of the photosensitive drum 12 remaining without being primarily transferred is removed by the removing blade 19.

  Next, the toner image primarily transferred to the transfer roll 24 reaches the secondary transfer position X2 by the rotation of the transfer roll 24, and is secondarily transferred to the medium P at the secondary transfer voltage. Accordingly, the non-volatile oil O is also transferred to the medium P together with the toner T constituting the toner image. The transport device 30 transports the medium P in synchronization with the timing at which the primary-transferred toner image reaches the secondary transfer position X2 together with the transfer roll 24.

  Next, the medium P on which the toner image is secondarily transferred is conveyed by the conveying device 30 and reaches the fixing device 40. The toner image secondarily transferred to the medium P is heated and pressurized by the fixing device 40 and fixed as an image on the medium P, and the image forming operation is completed.

<Configuration of main part (discharge device)>
Next, the structure of the main part (discharge device 130) of this embodiment will be described with reference to FIG. 1 and FIGS. 2 (A) and 2 (B). As shown in FIGS. 2A and 2B, the discharge device 130 includes a recovery path portion 132 and an electric field forming portion 134.

[Collection path section]
The collection path unit 132 connects the storage unit 100 and the developing roll 122, and functions as a recovery path for the liquid developer G that is collected from the development roll 122 and discharged to the storage unit 100. The collection path unit 132 includes a main body 132A and a blade 132B.

[Main unit]
As shown in FIGS. 2A and 2B, the main body 132 </ b> A is an L-shaped member lying down when the discharge device 130 is viewed from the front side. When the discharge device 130 is viewed from the front side, the main body 132A has a first path portion 132A1 inclined downward from the developing roll 122 side to the opposite side in the width direction, and an end portion on the opposite side in the width direction of the first path portion 132A1. 2nd path part 132A2 extended below from. An opening 132C is formed at the end of the first path portion 132A1 in the width direction on the developing roll 122 side. An opening 132D is formed at the lower end of the second path portion 132A2. In the main body 132A, an L-shaped through hole (collection path 133) is formed in a cross section when the discharge device 130 is viewed from the front side. Here, the second path portion 132A2 is an example of a discharge portion.

[blade]
The blade 132B is a long plate-like member. The longitudinal direction of the blade 132 </ b> B is disposed along the own axis direction of the developing roll 122. 2A and 2B, the blade 132B is fixed to the developing roller 122 side in the width direction on the lower surface of the first path portion 132A1 when the discharge device 130 is viewed from the front side. Yes. Specifically, a portion of one end side in the short direction on the lower surface in the thickness direction of the blade 132B is bonded to the upper surface of the lower surface of the first path portion 132A1 with an adhesive (not shown). As shown in FIG. 1, the other end side of the blade 132B in the short direction is on the outer peripheral surface of the developing roll 122 downstream of the nip portion N2 in the rotational direction of the developing roll 122 and more than the nip portion N1. It is in contact with the upstream part.

  As described above, the blade 132B collects the liquid developer G remaining on the developing roll 122 without being consumed on the outer peripheral surface of the photosensitive drum 12 by removing it from the developing roll 122. The recovered liquid developer G is pushed by its own weight and the liquid developer G to be recovered later because the first path portion 132A1 is inclined downward from the developing roll 122 side when viewed from the front side. By this, it is conveyed to the other side. The liquid developer G transported through the first path portion 132A1 is transported to the second path portion 132A2.

[Partition plate]
As shown in FIGS. 2A and 2B, a partition plate 140 is disposed at a site opposite to the later-described counter electrode 134 </ b> A in the collection path 133 on the opposite side of the developing roll 122. The partition plate 140 is a long plate, and is arranged along the own axis direction of the developing roll 122. Note that the second path portion 132A2 is disposed below the partition plate 140.

[Aperture]
As shown in FIGS. 2A and 2B, in the first path portion 132A1, a portion on the opposite side of the developing roller 122 with respect to the counter electrode 134A and above the partition plate 140, An opening 134E is formed. The opening 134E is connected to a waste toner tank (not shown).

[Electric field forming section]
As shown in FIGS. 2A and 2B, the electric field forming unit 134 has a function of forming an electric field on the liquid developer G collected from the developing roll 122 and conveyed. The electric field forming unit 134 includes a counter electrode 134A, a DC power supply 134B, and a wiring 134C.

[Counter electrode]
The counter electrode 134A is two flat electrodes 134A1 and 134A2. The electrodes 134A1 and 134A2 have a long shape. The electrodes 134 </ b> A <b> 1 and 134 </ b> A <b> 2 are arranged along the longitudinal direction of the developing roll 122 in the longitudinal direction. The electrodes 134A1 and 134A2 are fixed to the inner wall on the upper side of the main body 132A of the recovery path portion 132. The electrode 134A2 is fixed to the inner wall on the lower side. The electrodes 134A1 and 134A2 are arranged opposite to each other. In other words, the counter electrode 134 </ b> A that configures the electric field forming unit 134 is disposed in the first path unit 132 </ b> A <b> 1 (the recovery path 133) that configures the recovery path unit 132.

[DC power supply and wiring]
A DC power supply 134B is connected to the counter electrode 134A via a wiring 134C. The electrode 134A1 is connected to the positive electrode, and the electrode 134A2 is connected to the negative electrode.

  As described above, when a DC voltage is applied from the DC power supply 134B to the counter electrode 134A constituting the electric field forming unit 134, a DC electric field is formed in the liquid developer G transported between the counter electrodes 134A. It has become. For this reason, as shown in FIG. 2B, the negatively charged toner T is collected on the positive electrode 134A1. On the other hand, the positively charged toner T is collected on the negative electrode 134A2.

  In other words, the electric field forming unit 134 applies a DC voltage to the counter electrode 134A to form a DC electric field in the liquid developer G transported through the first path part 132A1. The electric field forming unit 134 sorts the toner T charged in the positive polarity from the toner T contained in the liquid developer G by collecting the toner T on the electrode 134A2. Here, the electrode 134A2 is an example of one electrode constituting the counter electrode 134A. The positively charged toner T is an example of a reusable polarity toner T.

  Since the partition plate 140 is disposed above the second path portion 132A2, the liquid developer G containing the positively charged toner T collected and selected by the electrode 132A is located below the partition plate 140. It is configured to be conveyed to a certain second path portion 132A2. Further, the second path portion 132A is configured to discharge the liquid developer G containing the positively charged toner T conveyed to the second path portion 132A to the storage unit 100.

  The negatively charged toner T collected on the positive electrode 134A1 is conveyed above the partition plate 140 and is disposed in a waste toner tank (not shown) from the opening 134E formed in the first path portion 132A1. ) To be discarded.

<Operation of First Embodiment>
Next, the operation of the present embodiment will be described in comparison with comparative embodiments (comparative embodiments 1 and 2) described below with reference to the drawings. In the following description, when using the components used in this embodiment, the description will be made using the reference numerals of the components as they are.

[Comparison with Comparative Aspect 1]
In the discharge device of Comparative Mode 1, the electric field forming unit 134 is not disposed in the collection path unit 132. Further, the opening 134E is not formed in the collection path portion 132. Further, the partition plate 140 is not disposed. Except for these points, the configuration is the same as that of the discharge device 130 of the present embodiment. Further, the developing device and the image forming apparatus according to Comparative Mode 1 are different from each other in the discharging device, and the other points are the same as those of the developing device 18 and the image forming apparatus 10 of the present embodiment.

  Next, the phenomenon that occurs in the developing device according to Comparative Mode 1 until the toner T constituting the liquid developer G accommodated in the accommodating portion 100 is transported through the collection path portion and discharged to the accommodating portion 100 will be described. .

  First, as shown in FIG. 1, the liquid developer G stored in the storage unit 100 is pumped up by the supply roll 112 that rotates about its own axis, and enters the nip portion N <b> 1 between the supply roll 112 and the development roll 122. When the supply electric field is formed, it is supplied to the developing roll 122.

  Next, the liquid developer G supplied to the developing roll 122 is charged to a positive polarity by the charging device 124.

  Next, the latent image formed on the photosensitive drum 12 is a liquid developer that is positively charged by the charging device 124 by forming a developing electric field at the nip portion N2 between the developing roll 122 and the photosensitive drum 123. G is developed as a toner image. At this time, a developing electric field is formed in the nip portion N <b> 2, so that the negatively charged toner T can be generated on the outer peripheral surface of the developing roll 122.

  Next, the liquid developer G remaining on the developing roll 122 without being supplied to the photosensitive drum 12 is removed by the blade 132 </ b> B of the discharge device and collected in the collection path unit 132. Note that the liquid developer G collected in the collection path portion may include toner T charged to a negative polarity.

  Next, the liquid developer G containing the negatively charged toner T collected in the first path part 132A1 is sent from the first path part 132A1 to the second path part 132A2, and from the second path part 132A2 to the storage unit 100. Can be discharged.

  In this manner, in the case of the developing device according to Comparative Mode 1, the negatively charged toner T can be mixed with the liquid developer G that is collected from the developing roll 122 and returns to the storage unit 100.

  The negatively charged toner T is likely to be electrostatically adsorbed to the positively charged toner T accommodated in the accommodating portion 100, and thus can become secondary particles. When the secondary particles are supplied to the developing roller 122, the secondary particles are aggregated with the toner T that is positively charged by the charging device 116 of the supplying unit 110 and the charging device 124 of the developing unit 120. It becomes easy and can become a larger secondary particle. As a result, the developing device of Comparative Mode 1 causes a development failure.

  On the other hand, also in the case of the developing device 18 of the present embodiment, the liquid developer G containing the negatively charged toner T is collected in the first path portion 132A1 constituting the collection path portion 132. In the discharge device 130 of the present embodiment, as shown in FIGS. 2A and 2B, the counter electrode 134A is disposed in the first path portion 132A1, and a DC voltage is applied to the counter electrode 134A. ing. Therefore, the negatively charged toner T is collected on the electrode 134A1 constituting the counter electrode 134A, as shown in FIG. Further, the positively charged toner T (reusable toner T) is collected on the electrode 134A2 as shown in FIG. 2B. The reusable toner T collected on the electrode 134A2 is sent to the second path portion 132A2 and discharged to the storage portion 100. On the other hand, the negatively charged toner T collected on the electrode 134A1 is discharged from the opening 134E formed in the first path portion 132A1 to the waste toner tank and discarded, and thus is not easily discharged to the storage unit 100.

  Therefore, according to the discharge device 130 of the present embodiment, the liquid developer G having a larger proportion of the reusable polarity toner T is discharged to the storage unit 100 as compared with the discharge device of the comparative form 1. In the present embodiment, the ratio of the reusable polarity toner T is the ratio of the positively charged toner T to the toner T contained in the liquid developer G discharged to the storage unit 100 (volume ratio). ).

  Accordingly, according to the developing device 18 of the present embodiment, the toner using the liquid developer G containing the toner T that is not reusable (the negatively charged toner T) as compared with the developing device of the comparative mode 1. Development defects due to image development are suppressed. Further, according to the image forming apparatus 10 of the present embodiment, image formation defects due to development defects are suppressed as compared with the image forming apparatus of Comparative Embodiment 1.

[Comparison with Comparative Aspect 2]
In the comparative mode 2, the SP value difference between the toner T of the liquid developer G used and the non-volatile oil O is different from that in the present embodiment. Specifically, the liquid developer used in Comparative Example 2 does not have a relationship in which the SP value difference between the toner T and the non-volatile oil O is 1.5 or more and 7.0 or less. Except this point, it is the same as the case of this embodiment.

  When the difference in SP value between the toner T and the non-volatile oil O is less than 1.5, the toner T is easily dissolved in the non-volatile oil O. In other words, since the affinity between the toner T and the non-volatile oil O is too high, the toner T tends to aggregate (the toner T tends to become secondary particles). Note that when a developer containing secondary particles of the toner T is used, image quality deterioration such as transfer of toner to a non-image portion and reduction of fine line reproducibility may occur.

  Further, when the difference in SP value between the toner T and the non-volatile oil O is larger than 7.0, the toner T and the non-volatile oil O are separated too much. If the toner T and the non-volatile oil O are excessively dispersed, the density of the toner image developed on the photosensitive drum 12 may be uneven.

  On the other hand, in the case of the present embodiment, the liquid developer used has a relationship in which the difference in SP value between the toner T and the non-volatile oil O is 1.5 or more. Then, the affinity between the toner T of this embodiment and the non-volatile oil O is lower than that in the case of the comparative example 2. For this reason, in the case of this embodiment, compared with the case of the comparative aspect 2, the toner T is less likely to aggregate (the toner T is less likely to become secondary particles).

  In the case of this embodiment, the liquid developer used has a relationship in which the difference in SP value between the toner T and the non-volatile oil O is 7.0 or less. As a result, the dispersibility between the toner T and the non-volatile oil O in the present embodiment does not cause the toner T and the non-volatile oil O to be separated too much as compared with the case of the comparative example 2.

  Therefore, according to the discharge device 130 of the present embodiment, the toner T is less likely to aggregate (difficult to become secondary particles) than the discharge device using the liquid developer of the comparative form 2.

<< Second Embodiment >>
Next, a second embodiment will be described with reference to FIG. In the following description, when using the components used in the first embodiment, the reference numerals of the components are used as they are.

<Configuration>
[Liquid developer and reusable toner]
The liquid developer G of the present embodiment has the same configuration as the liquid developer G of the first embodiment. However, in this embodiment, the reusable (size) toner T refers to secondary particles of the toner T having a predetermined size V1 or less, or primary particles of the toner T.

[Configuration of discharge device]
In the discharge device 130A of the present embodiment, the power source constituting the electric field forming unit 134 is an AC power source 136B. Further, the opening 134E is not formed in the collection path portion 132. Further, the partition plate 140 is not disposed. Then, the discharge device 130A applies an AC voltage to the counter electrode 134A to form an AC electric field in the liquid developer G conveyed through the recovery path section 132, whereby the toner T (two toner T contained in the liquid developer G). The secondary particles are loosened into reusable toner T (secondary particles or primary particles). Except for this point, the configuration is the same as that of the discharge device 130 of the first embodiment.

  In this embodiment, the distance between the electrodes of the counter electrode 134A is 5 mm as an example, and the AC voltage applied between the electrodes is a rectangular wave with an amplitude of 500 V, a duty of 50%, a maximum voltage of 500 V, and a minimum voltage of −500 V. It is a rectangular wave.

<Action>
Next, the operation of the present embodiment will be described with reference to FIG. In the following description, when using the components used in this embodiment, the description will be made using the reference numerals of the components as they are.

[Comparison with Comparative Aspect 1]
In the developing device of Comparative Mode 1, the following phenomenon may occur in addition to the phenomenon described above.

  The liquid developer G supplied from the supply roll 112 to the developing roll 122 is charged positively by the charging device 124. At this time, if the positive corona ions generated by the charging device 124 adhere to the toner T constituting the liquid developer G, the toner T easily aggregates and secondary particles of the toner T can be generated.

  In addition, the latent image formed on the photosensitive drum 12 is a liquid developer that is positively charged by the charging device 124 by forming a developing electric field at the nip portion N2 between the developing roll 122 and the photosensitive drum 123. G is developed as a toner image. At this time, a developing electric field is formed in the nip portion N2, so that the toner T easily aggregates and secondary particles of the toner T can be generated.

  As a result, in the developing device of Comparative Mode 1, the liquid developer G containing the secondary particles of the toner T collected in the first path portion 132A1 is sent from the first path portion 132A1 to the second path portion 132A2, and the second It can be discharged from the path portion 132A2 to the accommodating portion 100.

  In this manner, in the case of the developing device of Comparative Mode 1, secondary particles of the toner T can be mixed in the liquid developer G that is collected from the developing roll 122 and returned to the storage unit 100. Further, the secondary particles of the toner T discharged to the storage unit 100 may further aggregate with the toner T and become larger. When the secondary particles of the toner T are pumped up from the collection unit 100 to the supply roll 112 and supplied to the developing roll 122, a development failure occurs.

  On the other hand, also in the developing device 18 of the present embodiment, the liquid developer G containing the secondary particles of the toner T is transported to the first path portion 132A1 constituting the collection path portion 132. In the discharge device 130A of the present embodiment, as shown in FIGS. 3A and 3B, the counter electrode 134A is disposed in the first path portion 132A1, and an AC voltage is applied to the counter electrode 134A. ing. Therefore, the toner T constituting the secondary particles vibrates according to the charge amount, mass, etc. of each toner T while receiving a force from the AC electric field. At this time, since the distance between the toners T fluctuates, the non-volatile oil O is likely to penetrate between the toners T. Then, when the non-volatile oil O soaks between the toners T, the secondary particles of the toner T are loosened by the non-volatile oil O as shown in FIG. The liquid developer G containing the toner T loosened by the non-volatile oil O between the counter electrodes 134A (first path part 132A1) is transported to the second path part 132A2 and discharged to the storage unit 100.

  Therefore, according to the discharge device 130 </ b> A of the present embodiment, the liquid developer G in which the ratio of the reusable toner T is larger than that of the discharge device of the comparative form 1 is discharged to the storage unit 100. In the present embodiment, the ratio of the toner T having a reusable size is the ratio of the toner T having a predetermined size V1 or less to the toner T contained in the liquid developer G discharged to the storage unit 100. (Volume ratio).

Accordingly, according to the developing device 18 of the present embodiment, compared to the developing device of the comparative embodiment 1, the toner image is developed using the liquid developer G containing the toner T having a size that cannot be reused. Development defects are suppressed. Further, according to the image forming apparatus 10 of the present embodiment, image formation defects due to development defects are suppressed as compared with the image forming apparatus of Comparative Embodiment 1.
Other operations of the present embodiment are the same as those of the first embodiment.

«Third embodiment»
Next, a third embodiment will be described with reference to FIG. In the following description, when using the components used in the first and second embodiments, the description will be made using the reference numerals of the components as they are.

<Configuration>
[Liquid developer and reusable toner]
The liquid developer G of the present embodiment has the same configuration as the liquid developer G of the first embodiment. However, in the present embodiment, the reusable toner T refers to a toner T having a predetermined size V1 or less and a toner T charged to a positive polarity. The positive charge means that the charge amount of the toner T is charged positive as a whole.

  The negatively charged toner T collected on the positive electrode 134A1 is conveyed above the partition plate 140 and is disposed in a waste toner tank (not shown) from the opening 134E formed in the first path portion 132A1. ) To be discarded.

[Configuration of discharge device]
In the discharge device 130B of the present embodiment, the power sources constituting the electric field forming unit 134 are a DC power source 134B and an AC power source 136B connected in series. The discharging device 130B applies a DC voltage and an AC voltage to the counter electrode 134A, and forms an electric field in which the AC electric field is superimposed on the DC electric field on the liquid developer G transported through the recovery path 132. ing. In this embodiment, as an example, the distance between the electrodes of the counter electrode 134A is 5 mm, and the AC voltage applied between the electrodes is a rectangular wave having an amplitude of 500 V, a duty of 50%, a maximum voltage of 1000 V, and a minimum voltage of 0 V. Has been. The discharge device 130B disperses the toner T (primary particles or secondary particles) having a size not larger than the reusable size of the toner T (secondary particles) contained in the liquid developer G and has a reusable size. Among the toners T, the rechargeable positively charged toner T is collected at the electrode 134A2 and selected. Except for this point, the configuration is the same as that of the discharge device 130 of the first embodiment or the discharge device 130A of the second embodiment.

<Action>
In the discharge device 130 </ b> B of the present embodiment, the AC voltage is applied to the counter electrode 134 </ b> A, so that the secondary particles of the toner T are loosened by the non-volatile oil O. Further, since the positive DC voltage is applied to the electrode 134A1 of the counter electrode 134A, the negatively charged toner T is collected on the electrode 134A1 as shown in FIG. 4B. Further, the positively charged toner T is collected on the electrode 134A2 as shown in FIG. 4B. Then, the positively charged toner T collected on the electrode 134A2 is sent to the second path portion 132A2 and discharged to the storage portion 100. On the other hand, the negative toner T collected on the electrode 134A1 is discharged from the opening 134E formed in the first path portion 132A1 to the waste toner tank and is discarded, and thus is not easily discharged to the storage unit 100.

Therefore, according to the discharge device 130B of the present embodiment, the liquid developer G having a reusable size and a large proportion of the polar toner T is discharged to the storage unit 100 as compared with the discharge device of the comparative mode 1. Is done. The reusable size and the ratio of the polar toner T is a predetermined size V1 or less with respect to the toner T contained in the liquid developer G discharged to the storage unit 100 and has a positive polarity. It means the ratio (volume ratio) of the charged toner T.
Other operations of the present embodiment are the same as those of the first and second embodiments.

<< Fourth Embodiment >>
Next, a fourth embodiment will be described with reference to FIG. In the following description, when using the components used in the first to third embodiments, the description will be made using the reference numerals of the components as they are.

<Configuration>
[Liquid developer and reusable toner]
The liquid developer G of the present embodiment has the same configuration as the liquid developer G of the first embodiment. However, in the present embodiment, the reusable (size) toner T is a toner T having a predetermined size V1 or less.

[Configuration of discharge device]
In the discharge device 130C of the present embodiment, a mesh member 138 is disposed between the counter electrodes 134A and in a direction away from the electrodes 134A1 and 134A2 constituting the counter electrode 134A in a direction in which the counter electrode 134A faces. Here, as an example, the mesh member has an opening of 100 μm (an opening of 100 μm × 100 μm). Here, the mesh member 138 is an example of a member in which an opening or a gap through which the toner T having a predetermined size V2 or less can pass is formed. Further, in the present embodiment, the toner T having a predetermined size V2 or less means a toner T having a size or less that can pass through an opening of 100 μm × 100 μm. The predetermined size V2 is larger than the predetermined size V1 described above. Except for this point, the configuration is the same as that of the discharge device 130A of the second embodiment.

<Action>
As described above, in the discharge device 130A of the second embodiment, the toner T constituting the secondary particles receives the force from the AC electric field as shown in FIG. Is loosened by the non-volatile oil O.

  On the other hand, in the discharging device 130C of the present embodiment, among the secondary particles of the toner T that are subjected to a force by an alternating electric field, the secondary particles of the toner T larger than the size of the opening of the mesh member 138 are meshed. Hit 138. The secondary particles of the toner T are easily loosened by colliding with the mesh member 138. For this reason, according to the discharge device 130C of the present embodiment, more secondary particles of the toner T are loosened between the counter electrodes 134A than in the discharge device 130A of the present embodiment.

Therefore, according to the discharge device 130 </ b> C of the present embodiment, the liquid developer having a large proportion of reusable toner is discharged to the storage unit as compared with a discharge device in which no mesh member is disposed between the counter electrodes. Is done. Note that the ratio of the reusable toner T is the ratio (volume ratio) of the toner T having a predetermined size V1 or less with respect to the toner T contained in the liquid developer G discharged to the storage unit 100. Means.
Other operations of this embodiment are the same as those of the first, second, and third embodiments.

«Fifth embodiment»
Next, a fifth embodiment will be described with reference to FIG. In the following description, when using the parts used in the first to fourth embodiments, the description will be made using the reference numerals of the parts as they are.

<Configuration>
[Liquid developer and reusable toner]
The liquid developer G of the present embodiment has the same configuration as the liquid developer G of the first embodiment. However, in the present embodiment, the reusable toner T is a toner T that is charged to a predetermined size and positive polarity. The positive charge means that the charge amount of the toner T is charged positive as a whole.

[Configuration of discharge device]
<Configuration>
In the discharge device 130D of the present embodiment, the power sources constituting the electric field forming unit 134 are a DC power source 134B and an AC power source 136B connected in series. Except for this point, the configuration is the same as that of the discharging device 130C of the third embodiment.

<Action>
The discharge device 130D of the present embodiment has the action of combining the action of the discharge apparatus 130B of the third embodiment and the action of the discharge device 130D of the fourth embodiment.
Other operations of this embodiment are the same as those of the first, second, and third embodiments.

<< Sixth Embodiment >>
Next, a sixth embodiment will be described with reference to FIG. In the following description, when using the components used in the first to fifth embodiments, the description will be made using the reference numerals of the components as they are.

<Configuration>
[Liquid developer and reusable toner]
The liquid developer G of the present embodiment has the same configuration as the liquid developer G of the first embodiment. However, in the present embodiment, the reusable toner T refers to a toner T charged to a predetermined size V1 or less and positively charged. The positive charge means that the charge amount of the toner T is charged positive as a whole.

[Configuration of discharge device]
As shown in FIGS. 7A and 7B, the discharge device 130 </ b> E of the present embodiment is configured to include a recovery path portion 232 and an electric field forming portion 234. Hereinafter, a different part from the discharge apparatus 130 of 1st Embodiment mentioned above is demonstrated.

  In the discharge device 130E of the present embodiment, one electrode constituting the counter electrode 234A is a mesh member 234A1, and the polarity of the toner T is larger than the size V3 determined for the one electrode or the reusable toner T. Different toners T are collected, and reusable polar toners T are collected and sorted on the other electrode. Here, the mesh member 234A1 is an example of a member in which an opening or a gap through which toner having a predetermined size V3 or less can pass is formed. The predetermined size V3 is larger than the predetermined size V1 described above.

[Collection path section]
The collection path unit 232 includes a main body 232A and a blade 132B. In the main body 232A, the upper inner wall and the lower inner wall of the first path portion 232A1 are separated when the discharge device 130E is viewed from the front side as compared with the main body 132A of the first embodiment.

[Electric field forming section]
Unlike the electric field forming unit 134 of the first embodiment, the electric field forming unit 234 has an upper electrode formed of a mesh member 234A1. The mesh member 234A1 is not fixed to the upper inner wall of the first path portion 232A1, but is disposed at a portion separated from the upper inner wall and the lower inner wall of the first path portion 232A1. In the present embodiment, the mesh member 234A1 is fixed to the side surface (not shown) of the first path portion 232A1.

[Other configurations]
In the discharge device 130E of the present embodiment, the first path portion 232A1 is divided into an upper path portion 232A11 and a lower path portion 232A12 by the mesh member 234A1. The liquid developer G collected from the photosensitive drum 12 by the blade 132B is first conveyed to the upper path portion 232A11. The liquid developer G transported to the upper path portion 232A11 passes through the mesh member 234A1 by its own weight and is transported to the lower path portion 232A12. Note that the liquid developer G conveyed to the lower path portion 232A12 is discharged from the second path portion 132A2 to the storage unit 100.

<Action>
The liquid developer G collected from the developing roll 122 is conveyed to the upper path portion 232A11. Here, a positive DC voltage is applied to the mesh member 234A1, and a negative DC voltage is applied to the electrode 134A2. Therefore, among the toner T constituting the liquid developer G conveyed to the upper path portion 232A11, the negatively charged toner T is electrostatically attracted (trapped) to the mesh member 234A1. Further, the secondary particles of the toner T larger than the opening of the mesh member 234A1 cannot pass through the opening of the mesh member 234A1 (is trapped).

  Here, the toner T contained in the liquid developer G that passes through the mesh member 234A1 and is transported to the lower path portion 232A12 is secondary particles of the toner T that can pass through the opening of the mesh member 234A1. The toner T is positively charged.

  Next, the positively charged toner T conveyed to the lower path portion 232A12 is electrostatically attracted and collected by the electrode 134A2 to which the negative DC voltage is applied.

  Next, the positively charged toner T collected and selected by the electrode 134A2 is sent to the second path portion 132A2 and discharged to the storage portion 100.

Therefore, according to the discharge device 130E of the present embodiment, the liquid developer G having a reusable size and a large proportion of the polar toner T is discharged to the storage unit as compared with the discharge device of the comparative aspect 1. The Note that the ratio of the reusable toner T is the ratio of the positive toner T that is equal to or less than a predetermined size V1 with respect to the toner T contained in the liquid developer G discharged to the storage unit 100. (Volume ratio).
Other operations of the present embodiment are the same as those of the first to fourth embodiments.

  As mentioned above, although this invention was demonstrated in detail about specific embodiment, this invention is not limited to embodiment mentioned above, Other embodiment is possible within the scope of the present invention.

  For example, in each embodiment, an example of the carrier liquid constituting the liquid developer G has been described as the non-volatile oil O. However, if the liquid developer G containing the reusable toner T is discharged from the recovered liquid developer G by the discharge devices 130 and 130A to 130E of the embodiments, the carrier liquid constituting the liquid developer G is discharged. May not be non-volatile oil O. In other words, when the liquid developer G is conveyed to the collection path part 132, an electric field may be formed by the electric field forming part 134 constituting the discharge devices 130 and 130A to 130E. For example, the carrier liquid may be a petroleum volatile solvent. Moreover, non-volatile solvents, such as vegetable oil, may be sufficient.

  In each embodiment, the reusable toner T has been described as dropping from the opening 132D formed in the second path portion 132A2 of the collection path portion 132 and being discharged to the storage unit 100. However, if the reusable toner T is sorted or dispersed by the electric field forming units 134 and 234, the configuration in which the sorted or dispersed reusable toner T is discharged to the storage unit 100 is different from the present embodiment. It may be a configuration. For example, the reusable toner T may be conveyed to the storage unit 100 by a belt conveyor.

  In each embodiment, the reusable toner T has been described as being discharged to the storage unit 100 from the opening 132D formed in the second path part 132A2 of the recovery path part 132. However, when discharged from the discharge devices 130 and 130A to E and finally stored in the storage unit 100, the liquid developer G containing the reusable toner T is discharged from the discharge devices 130 and 130A to E. It does not have to be stored directly in the storage unit 100. For example, the toner may be conveyed to the storage unit 100 after being discharged to a toner concentration measuring device that measures the toner concentration, a circulation path of the liquid developer G, a toner concentration adjusting device, and other devices.

  Further, in each embodiment, it has been described that the reusable toner T discharged from the discharge devices 130 and 130A to E falls into the storage unit 100 due to its own weight. However, a toner concentration measuring device is disposed on the downstream side in the transport direction of the liquid developer G with respect to the discharge units 136 of the discharge devices 130 and 130A to 130E and on the upstream side with respect to the storage unit 100, and the discharged toner T Alternatively, the concentration may be detected. In this case, since the toner T discharged from the discharge unit 136 is a reusable toner T, the measurement accuracy of the toner density is improved.

  When the toner concentration measuring device is arranged, the electric field strength formed on the counter electrodes 134A and 234A by the control unit 50 may be changed according to the detected toner concentration. For example, in the case of the first, third, fifth, or sixth embodiment, if the toner concentration detected by the toner concentration measuring device is lower than a predetermined value, the DC voltage of the counter electrodes 134A, 234A is increased. You may make it do. In the second to fifth embodiments, when the toner concentration detected by the toner concentration measuring device is lower than a predetermined value, the amplitude or frequency of the AC voltage of the counter electrode 134A may be increased. .

  Further, the AC voltage applied to the counter electrode 134A of the discharge device 130A of the second embodiment has been described as a rectangular wave having an amplitude of 500V, a duty of 50%, a maximum voltage of 500V, and a minimum voltage of -500V. However, the maximum voltage may not be 500 V and the minimum voltage may not be −500 V as long as an AC electric field is formed for the liquid developer G conveyed between the counter electrodes 134A. For example, both the maximum voltage and the minimum voltage may be larger than 0V. Further, both the maximum voltage and the minimum voltage may be smaller than 0V. Further, the maximum voltage or the minimum voltage may be 0V.

  Further, the AC voltage applied to the counter electrode 134A of the discharge device 130B of the third embodiment has been described as a rectangular wave having an amplitude of 500V, a duty of 50%, a maximum voltage of 1000V, and a minimum voltage of 0V. However, if an AC electric field is formed for the liquid developer G conveyed between the counter electrodes 134A and the electrode 134A2 is a negative electrode relative to the electrode 134A1, the maximum voltage is 1000V, The minimum voltage may not be 0V. For example, both the maximum voltage and the minimum voltage may be larger than 0V. Further, both the maximum voltage and the minimum voltage may be smaller than 0V. Further, the maximum voltage or the minimum voltage may be 0V.

  In the discharge device 130A of the second embodiment and the discharge device 130B of the third embodiment, the AC voltage waveform is described as a rectangular wave. However, a triangular wave, a sine wave, or other waveform may be used as long as it is an alternating voltage. Further, when the waveform of the AC voltage is a rectangular wave, the duty may not be 50%.

  Further, since the image forming apparatus 10 of each embodiment has been described as the image forming unit 20 forms a single color toner image on the medium P, the image forming apparatus 10 can form only a single color image. However, a plurality of image forming units 20 are arranged along the conveyance direction of the medium P (for example, four corresponding to four colors of black, cyan, magenta, and yellow) to form a color image. You may do it.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 11 Image forming unit 12 Photosensitive drum (an example of an image holding body)
16 Exposure device 18 Development device 22 Transfer unit (an example of transfer device)
40 Fixing Device 100 Storage Unit 112 Supply Roll (Example of Supply Member)
122 Developing roll (an example of a developing member)
130 discharge device 130A discharge device 130B discharge device 130C discharge device 130D discharge device 130E discharge device 132 collection path part 133 collection path 134 electric field forming part 134A counter electrode 134A1 electrode 134A2 electrode 136 discharge part 138 mesh member (of a predetermined size or less) An example of a member in which an opening or a gap in which toner can move is formed)
234A1 mesh member (an example of a member in which an opening or a gap in which toner of a predetermined size or less is movable is formed)
G Liquid developer O Non-volatile oil (an example of carrier liquid)
P Medium T Toner

Claims (9)

Recovery of a liquid developer that connects a storage unit that stores a liquid developer containing toner and a developing member that develops a latent image formed on the image carrier with the liquid developer stored in the storage unit as a toner image. An electric field forming unit disposed in the path and forming an electric field on the liquid developer recovered from the developing member;
A discharge unit that discharges reusable toner conveyed from the electric field forming unit to the storage unit;
Ejector equipped with. The electric field forming unit is configured to include a counter electrode, and collects and sorts reusable toner on one electrode constituting the counter electrode by applying a voltage to the counter electrode,
The discharge unit is configured to convey reusable polarity toner from one electrode constituting the counter electrode.
The discharging apparatus according to claim 1. The electric field forming unit is configured to include a counter electrode, and an AC voltage is applied to the counter electrode to make the toner contained in the liquid developer a reusable toner.
The discharging apparatus according to claim 1. The electric field forming unit includes a counter electrode,
Applying a voltage in which an AC voltage is superimposed on a DC voltage to the counter electrode, collecting and sorting toner of a size that can be reused on one electrode constituting the counter electrode, and polarity,
The discharge unit is configured to be reusable in size and from a polarity toner from one electrode constituting the counter electrode.
The discharging apparatus according to claim 1. The electric field forming unit includes a counter electrode,
A member that is disposed between the counter electrodes and that has an opening or gap that allows toner of a predetermined size or less to pass in a direction in which the counter electrodes face each other;
The discharge device according to any one of claims 1 to 4, further comprising: One electrode constituting the counter electrode is a member in which an opening or a gap through which toner of a predetermined size or less can pass is formed,
The electric field forming unit applies a DC voltage to the counter electrode so that the polarity of the member becomes the polarity of reusable toner, so that the electric field forming unit is larger than a size determined for one electrode constituting the counter electrode. Collect toner that is different in polarity from large toner or reusable toner, and collect and sort reusable and polar toner on the other electrode,
The discharge unit is configured to be reusable in size and from a polarity toner from one electrode constituting the counter electrode.
The discharging apparatus according to claim 2. The liquid developer includes a carrier liquid,
The difference in SP value between the toner and the carrier liquid has a relationship of 1.5 or more and 7.0 or less.
The discharge device according to claim 1. An accommodating portion for accommodating a liquid developer containing toner;
A developing member for developing a latent image formed on the image carrier as a toner image with a liquid developer;
The discharge device according to claim 1, wherein a liquid developer is collected from the developing member and reusable toner is discharged.
A storage unit for storing reusable toner discharged from the discharge device;
A developing device comprising: An image carrier,
An exposure device that exposes the image carrier to form a latent image;
A developing device according to claim 8;
A transfer device for transferring the toner image developed on the image carrier to a medium;
A fixing device for fixing the toner image transferred to the medium to the medium;
An image forming apparatus.

Images