JP2015184368A - Developing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress adhesion of an aggregate of toner to a developing member.SOLUTION: An image forming apparatus 10 includes: a developing member 102 that develops a latent image formed on an image holding body 12 into a toner image with a liquid developer G containing a toner T and a carrier oil O; a storage body 140 that stores the liquid developer; a supply member 112 that is rotatably provided with the axial direction aligned with the developing member 102 and is partially immersed in the liquid developer G in the storage body 140 to supply the liquid developer G to the developing member 102; a regulation member 114 that regulates the amount of liquid developer and returns the liquid developer G absorbed by the supply member 112 to the inside of the storage body 140; a stirring member 120 that is arranged immersed in the liquid developer G stored in the storage body 140 to convey the liquid developer in a determined direction; and a contact member 130 that is attached to the stirring member 120 and rotates in contact with an inner wall 142 of the storage body 140 in association with the rotation of the stirring member 120.

Description

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

  Patent Document 1 discloses a liquid developer developing device that includes a liquid developer metering roller, a doctor blade that contacts the metering roller, and a liquid developer reservoir disposed below the liquid developer metering roller. An apparatus is disclosed. In the liquid developer developing device of Patent Document 1, hairs are planted in the form of screw blades on the surface of the liquid developer reservoir, and a pair of screw brush rollers having the same twist direction are brought close to each other. And the bristles are brought into contact with the surface of the metering roller and rotated in opposite directions.

  Japanese Patent Application Laid-Open No. 2004-228688 discloses an agent container that contains a liquid developer containing a developing substance and a liquid carrier, a developer carrier that carries a liquid developer supplied from the agent container, and a liquid in the agent container. A developing device is disclosed that includes a stirrer that stirs by rotating the developer in a horizontal direction. The developing device of Patent Document 2 develops a latent image by attaching a developing substance in a liquid developer carried on a developer carrying member to a latent image carried on the latent image carrying member of the image forming apparatus. In the developing device disclosed in Patent Document 2, a flexible stirrer is provided.

  In Patent Document 3, a replenishing port and a recovery port are arranged, and a developer container for storing a liquid developer, a developer carrier for supporting the liquid developer, and a liquid developer stored in the developer container are developed. A developing device having a supply roller for supplying to the agent carrier is disclosed. The developing device of Patent Document 3 is provided in a developer container, and includes a transport screw having a different transport amount of the liquid developer to the second shaft end side opposite to the first shaft end side. Yes.

JP 2001-282003 A JP 2002-023502 A JP 2009-229630 A

  An object of the present invention is to suppress adhesion of toner aggregates to a developing member.

According to a first aspect of the present invention, there is provided a developing member for developing a latent image formed on an image carrier as a toner image with a liquid developer containing toner and carrier oil while rotating about its own axis, and a liquid A container that contains the developer, and the developer member is provided so as to be rotatable in the same axial direction as the developing member. While rotating about its own axis, a part of the container is immersed in the liquid developer of the container, A supply member that supplies a liquid developer; a restriction member that is disposed above the container and restricts the amount of the liquid developer; and returns the liquid developer removed by the supply member to the container. A stirrer that is placed in a liquid developer accommodated in the container and is rotated around its own axis while being transported in a predetermined direction, attached to the stirrer, and with the rotation of the stirrer, Inner wall of the container A contact member that rotates while being in contact,
It has.

  A developing device according to a second aspect of the present invention is the developing device according to the first aspect, wherein the contact member rotates while being bent and contacting the inner wall of the container as the stirring member rotates.

  The developing device according to claim 3 of the present invention is the developing device according to claim 1 or 2, wherein a groove is formed on the inner wall of the container when the container is viewed from above. The contact member rotates while contacting the groove bottom of the groove as the stirring member rotates.

  The developing device according to a fourth aspect of the present invention is the developing device according to any one of the first to third aspects, wherein the contact member or the groove bottom of the groove is made conductive and grounded. Yes.

  The developing device according to claim 5 of the present invention is the developing device according to any one of claims 1 to 3, wherein the contact member and the groove bottom of the groove are electrically conductive and electrically connected to each other. Has been.

  According to a sixth aspect of the present invention, there is provided an image forming apparatus, an image holding member, a charging device that charges the image holding member, and an exposure device that exposes the image holding member charged by the charging device to form a latent image. And developing the latent image formed on the image carrier with a liquid developer as a toner image, and a toner image developed on the image carrier, And a transfer device for transferring to the transfer body.

  According to the developing device of the first aspect of the present invention, adhesion of toner aggregates to the developing member is suppressed as compared with a developing device that does not include the contact member of this configuration.

  According to the developing device of the second aspect of the present invention, toner agglomerates are more easily redispersed than a developing device including a contact member that rotates while not contacting the inner wall of the container.

  According to the developing device of the third aspect of the present invention, toner agglomerates are easily redispersed as compared with a developing device in which a groove is not formed on the inner wall of the container.

  According to the developing device of the fourth aspect of the present invention, compared to the developing device in which the contact member and the groove bottom of the groove are not grounded, the aggregate of the overcharged toner is easily redispersed.

  According to the developing device of the fifth aspect of the present invention, the efficiency of redispersing the aggregates of the overcharged toner can be increased as compared with the developing device having no potential difference between the contact member and the groove bottom.

  According to the image forming apparatus of the sixth aspect of the present invention, image formation defects caused by adhesion of toner aggregates to the developing member are suppressed as compared with an image forming apparatus that does not include the developing device of this configuration. The

1 is a schematic view (front view) of an image forming apparatus according to a first embodiment. FIG. 3 is a schematic view (front view) of a part of an image forming unit and a transfer roll constituting the image forming apparatus of the first embodiment. 2A and 2B are diagrams illustrating a part of the developing device according to the first embodiment, in which FIG. 1A is a cross-sectional view of a part of a stirring member, a contact member, and a container, and FIG. It is a top view of a part. 3A and 3B are diagrams illustrating a part of the developing device according to the first embodiment, in which FIG. 3A is an enlarged view of a portion surrounded by a two-dot chain line in FIG. 3A, and FIG. It is an enlarged view of the site | part enclosed by the dotted line. 2A and 2B are diagrams illustrating a state of toner in carrier oil, where FIG. 1A is a schematic diagram illustrating a micro state in which two toners are dispersed in carrier oil, and FIG. 2B is a plurality of toners in carrier oil. (C) is a schematic diagram showing a macro state in which a plurality of toners are aggregated in the carrier oil. It is a figure which shows a part of developing device of 2nd Embodiment, Comprising: It is a schematic diagram which shows a stirring member, a contact member, a part of container, and an electrical pathway. It is a figure which shows a part of developing device of 3rd Embodiment, Comprising: It is a schematic diagram which shows a stirring member, a contact member, a part of container, and an electrical pathway. It is a figure which shows a part of developing device of 4th Embodiment, Comprising: It is a schematic diagram which shows a stirring member, a contact member, a part of container, and an electrical pathway. It is a figure which shows a part of developing apparatus of 5th Embodiment, Comprising: It is a schematic diagram which shows a stirring member, a contact member, a part of container, and an electrical pathway.

≪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 (developing device) of the first embodiment will be described. Next, the configuration and operation of the second to fourth embodiments will be described.

<< First Embodiment >>
<< 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 the drawings. As shown in FIG. 1, the image forming apparatus 10 includes a conveyance device 30, an image forming unit 35, a fixing device 40, and a control unit (not shown). The operation of each unit of the image forming apparatus 10 is controlled by a control unit (not shown).

  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.

[Conveyor]
As shown in FIG. 1, the transport device 30 has a function of transporting the medium P in a direction indicated by an arrow A (transport 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. Here, the medium P is an example of a transfer body.

(Image forming part)
As shown in FIG. 1, the image forming unit 35 has a function of forming a toner image using a liquid developer G containing toner T and carrier oil O on a medium P conveyed by the conveying device 30. The image forming unit 35 includes image forming units 26K, 26C, 26M, and 26Y. The image forming units 26K, 26C, 26M, and 26Y include image forming units 11K, 11C, 11M, and 11Y, and transfer units 20K, 20C, 20M, and 20Y, respectively. Here, the subscripts K, C, M, and Y indicate the toner colors of the toner T to be used in the image forming units 26K, 26C, 26M, and 26Y and the members constituting them. The image forming units 26K, 26C, 26M, and 26Y have the same configuration except for the toner color of the toner T to be used. Accordingly, in FIG. 1, the reference numerals of the components constituting the image forming units 26C, 26M, and 26Y are omitted. Here, the transfer unit 20 is an example of a transfer device.

  In the following description, the subscripts K, C, M, and Y are omitted for the image forming units 26K, 26C, 26M, and 26Y and the members constituting them when the distinction for each toner color is unnecessary.

<Image forming unit>
As shown in FIGS. 1 and 2, the image forming unit 11 includes a photosensitive drum 12, a charging device 14, an exposure device 16, a developing device 18, a cleaning blade 19, and a developer supply device 160. I have. The charging device 14, the exposure device 16, the developing device 18, and the cleaning blade 19 are arranged around the photosensitive drum 12 in this order in the R1 direction. The developer supply device 160 is disposed around the developing device 18. 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.

(Developer)
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 (Y direction) of the photosensitive drum 12.

  As shown in FIGS. 1 and 2, the developing device 18 includes a developing unit 100, a supply unit 110, a stirring member 120, a contact member 130, and a container 140. The liquid developer G is stored in the container 140 as shown in FIG. Since the developing device 18 is a main part of the present embodiment, the developing device 18 will be described later.

(Developer replenishment device)
The developer replenishing device 150 has a function of replenishing the developing device 18 with the liquid developer G. As shown in FIG. 2, the developer replenishing device 150 includes a recovery path unit 152A, a supply path unit 152B, a storage unit 154, a stirring unit 156, a pump 158, and a concentration sensor (not shown). It is configured to include.

  One end of the recovery path portion 152A is connected to the upper portion of the container 140. The recovery path 152A recovers the liquid developer G when the liquid level of the liquid developer G stored in the container 140 reaches a predetermined position.

  The other end of the recovery path portion 152A is connected to the stirring portion 156. The agitation unit 156 includes a container 156A and an agitation member 156B that is accommodated in the container 156A and agitates the liquid developer G.

  The stirring unit 156 is connected to the storage unit 154. The storage unit 154 includes a container 154A that stores the liquid developer G, a transport path unit 154C that transports the liquid developer G from the container 154A to the container 156A, and a valve 154B that is disposed in the transport path unit 154C. Yes.

  The liquid developer G collected in the collection path 152A is sent into the container 156A of the stirring unit 156. Further, the liquid developer G stored in the storage unit 154 is sent from the container 154A to the container 156A via the conveyance path unit 154C when the valve 154B of the conveyance path unit 154C is opened. The stirring member 156B of the stirring unit 156 stirs the liquid developer G sent from the recovery path unit 152A and the transport path unit 154C.

  One end portion of the supply path portion 152B is connected to the stirring portion 156. Further, the other end portion of the supply path portion 152 </ b> B is connected to an upper portion of the container 140. A pump 158 is disposed in the supply path portion 152B. The supply path portion 152 </ b> B is configured to send the liquid developer G sent out from the stirring portion 156 to the container 140 by the pump 158.

  A density sensor (not shown) that detects the density of the toner T in the liquid developer G is disposed in the supply path portion 152B. The signal detected by this density sensor is sent to the control unit. Then, the control unit opens and closes the valve 154B of the storage unit 154 based on the value of the detected signal so that the concentration of the toner T of the liquid developer G in the container 140 falls within a predetermined range. The operation is to be performed.

  As described above, the developer replenishing device 150 adjusts the concentration of the toner T of the liquid developer G in the container 140 of the developing device 18 and refills the container 140 with the liquid developer G. Yes.

(Cleaning blade)
The cleaning blade 19 removes the liquid developer G remaining on the outer peripheral surface of the photoconductive drum 12 from the outer peripheral surface of the photoconductive drum 12 after the primary transfer of the transfer rolls 22 of the toner images of the respective colors is completed. It has a function of cleaning the outer peripheral surface of the drum 12. The cleaning blade 19 includes a blade.

<Transfer unit>
The transfer unit 20 has a function of primarily transferring a toner image developed on the photoconductive drum 12 by the developing device 18 from a photoconductive drum 12 to a transfer roll 22 described later, and performing secondary transfer onto a conveyed medium P. . The transfer unit 20 includes a transfer roll 22 and a backup roll 24.

(Transfer roll)
The transfer roll 22 is in contact with the photosensitive drum 12 at the upstream side of the charging device 14 and the downstream side of the developing device 18 (primary transfer position X1) in the rotation direction of the photosensitive drum 12, and is indicated by an arrow R2. It is designed to rotate following the direction. As a result, the transfer unit 20 primarily transfers the toner image formed on the outer peripheral surface of the photosensitive drum 12 to the transfer roll 22 at the primary transfer position X1. The transfer roll 22 is configured to transfer oil O with the primary transfer of the toner image. A primary transfer voltage is applied between the photosensitive drum 12 and the transfer roll 22 by a power source (not shown).

(Backup roll)
The backup roll 24 comes into contact with the transfer roll 22 at a portion (secondary transfer position X2) opposite to the photosensitive drum 12 with the transfer roll 22 in between, and is driven to rotate in the direction indicated by the arrow R3. ing. As a result, the transfer unit 20 secondarily transfers the toner image primarily transferred to the transfer roll 22 to the medium P at the secondary transfer position X2. In addition, the oil P is transferred to the medium P along with the secondary transfer of the toner image. A secondary transfer voltage is applied between the transfer roll 22 and the backup roll 24 by a power source.

[Fixing device]
The fixing device 40 has a function of fixing a toner image on the medium P as an image on the medium P. The fixing device 40 includes a fixing roll 42, a pressure roll 44, and a halogen heater 46.

  The pressure roll 44 is disposed so as to face the fixing roll 42 with the medium P interposed therebetween. The pressure roll 44 has a function of pressing the medium P and pressing the fixing roll 42 with the medium P interposed therebetween. The fixing roll 42 is formed in a cylindrical shape. The halogen heater 76 is disposed in the inner peripheral surface of the fixing roll 72 and heats the fixing roll 72 to a temperature equal to or higher than the toner melting temperature of the toner T. When the fixing roll 72 is pressed by the pressure roll 74, the fixing roll 72 is recessed to form a nip portion with the medium P. As described above, the fixing device 40 heats and pressurizes the toner image on the medium P that passes through the nip portion, and fixes the toner image on the medium P as an image.

[Liquid developer]
The liquid developer G used in the present embodiment is a liquid type developer obtained by dispersing powder toner T in carrier oil O (see FIGS. 5B and 5C). In the present embodiment, the toner T includes, as an example, a polyester resin as a main component. The carrier oil O is, for example, dimethyl silicone oil (a kind of silicone oil). The average particle diameter of the toner T is 2 to 5 μm, and the toner T cannot enter the medium P at room temperature. On the other hand, since the oil O is a liquid, it can penetrate into the medium P even at room temperature.

<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.

  In the image forming unit 11K constituting the image forming unit 26K, the photosensitive drum 12K rotates, and the outer peripheral surface of the photosensitive drum 12K is charged by the charging device 14K. Next, the outer peripheral surface of the charged photosensitive drum 12 </ b> K is exposed by the exposure device 16 </ b> K, whereby an electrostatic latent image (not shown) of the first color (K) is formed on the outer peripheral surface of the photosensitive drum 12. Is done. The electrostatic latent image is developed as a toner image by the developing device 18K.

  The toner image reaches the primary transfer position X1 by the rotation of the photosensitive drum 12K, and is primarily transferred to the transfer roll 22K with the primary transfer voltage. Along with this, the carrier oil O is also transferred to the transfer roll 22K together with the toner T constituting the toner image. The toner image transferred to the transfer roll 22K reaches the secondary transfer position X2 by the rotation of the transfer roll 22K, and is secondarily transferred to the medium P at the secondary transfer voltage. Along with this, the carrier oil O also moves to the medium P together with the toner T constituting the toner image.

  Similarly, the second color (C), third color (M), and fourth color (Y) toner images formed by the image forming units 26C, 26M, and 26Y pass through the transfer rolls 22C, 22M, and 22Y. Then, secondary transfer is sequentially performed so as to overlap the medium P. In this way, on the medium P, toner images of the first color (K), the second color (C), the third color (M), and the fourth color (Y) (hereinafter referred to as color toner images). Is formed.

  After the primary transfer of the first color (K) toner image, the photosensitive drum 12K is cleaned by removing the liquid developer G remaining on the outer peripheral surface of the photosensitive drum 12K by the cleaning blade 19K. Similarly, the photosensitive drums 12C, 12M, and 12Y are cleaned by removing the liquid developer G by the cleaning blades 19C, 19M, and 19Y.

  The medium P on which the color toner image is formed is transported by the transport device 30 and reaches the fixing device 40. The color toner image is heated and pressurized by the fixing device 40 and fixed on the medium P as an image.

  When forming a monochrome image on the medium P, for example, when forming a black (K) image, the other image forming units 11C, 11M, and 11Y are separated from the transfer rolls 22C, 22M, and 22Y, respectively. (Retracted).

<Configuration of main part (developing device)>
Next, the configuration of the main part (developing device 18) of this embodiment will be described with reference to the drawings.

[Development part]
As shown in FIG. 2, the developing unit 100 includes a developing roll 102 and a removing member 104.

<Development roll>
The developing roll 102 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. The developing roll 102 is a long and cylindrical member. Here, the developing roll 102 is an example of a developing member.

  The developing roll 102 is subjected to development by applying a voltage from a power source (not shown) and forming a predetermined electric field (hereinafter referred to as a developing electric field) with the photosensitive drum 12. ing.

<Removal member>
The removing member 104 has a function of removing the liquid developer G remaining on the outer peripheral surface of the developing roll 102 from the outer peripheral surface of the developing roll 102 after the development of the toner image. The removal member 104 includes a removal blade 104A and a support plate 104B. The removal blade 104A is a long and plate-like member. The support plate 104B is a long plate-like member. One end side of the removal blade 104 in the short direction is bonded to the support plate 104B. The other end side in the short direction of the removal blade 104 is in contact with the outer peripheral surface of the developing roll 102 along the longitudinal direction of the developing roll 102. The liquid developer G removed from the outer peripheral surface of the developing roll 102 by the removing member 104 is caused to flow in the upper surface of the removing member 104 by its own weight and dropped into the container 140. .

[Supply section]
As shown in FIGS. 1 and 2, the supply unit 110 includes a supply roll 112 and a regulating member 114.

<Supply roll>
The supply roll 112 has a function of supplying the liquid developer G to the developing roll 102 while rotating around its own axis. The supply roll 112 is a long and cylindrical member. The supply roll 112 is rotatable with the developing roll 102 aligned in the axial direction. A part of the supply roll 112 is immersed in the liquid developer G accommodated in the container 140. Further, the supply roll 112 forms a nip portion together with the developing roll 102. Then, a voltage is applied to the supply roll 112 by a power source (not shown), and a predetermined electric field (hereinafter referred to as a supply electric field) is formed between the supply roll 112 and the development roll 102, thereby supplying the liquid developer G to the development roll. 102 is supplied. Here, the supply roll 112 is an example of a supply member.

<Regulating member>
The regulating member 114 has a function of returning the liquid developer G on the outer circumferential surface of the supply roll 112 into the container 140 and regulating the amount of the liquid developer G on the outer circumferential surface of the supply roll 112. Specifically, the regulating member 114 returns the liquid developer G into the container 140 by scraping off the liquid developer G on the outer peripheral surface of the supply roll 112. The restriction member 114 is a long and plate-like member. Further, the regulating member 114 is disposed on the upper side of the container 140 so as to contact the outer peripheral surface of the supply roll 112.

[Stirring member]
The agitating member 120 has a function of agitating the liquid developer G accommodated in the accommodating body 140 and transporting it in a predetermined direction (apparatus depth direction). As illustrated in FIGS. 1 to 3, the stirring member 120 includes a shaft 120 </ b> A and a spiral body 120 </ b> B. The shaft 120A is disposed along the apparatus depth direction. The spiral body 120B protrudes spirally from the outer peripheral surface of the shaft 120A. The stirring member 120 is disposed soaked in the liquid developer G stored in the container 140. Note that the spiral portion 120 </ b> B of the stirring member 120 is disposed away from the inner wall 142 of the container 140.

  In the present embodiment, two stirring members 120 are provided. The two stirring members 120 are arranged so as to be rotatable with their axial directions aligned. When the developing device 18 is viewed from the front side, the stirring member 120 on the right side in the device width direction conveys the liquid developer G from the near side to the far side of the developing device 18 (container 140). In contrast, the stirring member 120 on the left side in the apparatus width direction conveys the liquid developer G from the back side to the front side of the developing device 18 (container 140). In this manner, the liquid developer G in the container 140 is circulated while being stirred in the container 140.

(Contact member)
The contact member 130 has a function of rotating while contacting the inner wall 142 of the container 140 as the stirring member 120 rotates. The contact member 130 is a plate-like elastic member (see FIGS. 1 to 4). In this embodiment, the contact member 130 is a PET (polyethylene terephthalate) film as an example. One end side in the longitudinal direction of the contact member 130 is attached to the shaft 120A of the stirring member 120 as shown in FIGS. And when the contact member 130 rotates in the state which the other end side of the longitudinal direction of the contact member 130 contacted the inner wall 142 of the container 140, the contact member 130 is comprised so that it may bend.

  As shown in FIG. 3B, a plurality of contact members 130 are arranged along the axial direction of the shaft 120A.

[Container]
The container 140 has a function of containing the liquid developer G as shown in FIGS. When viewed from the front side, the container 140 is formed with two arcuate surfaces on the lower side, the arcuate shape of which has a recess whose opening is upward in cross section. Two arcuate surfaces are formed along the depth direction of the apparatus. The two arc surfaces are aligned in the apparatus width direction. Then, the two stirring members 120 in the container 140 are arranged so that the axial center thereof coincides with the center of each arc surface.

  As shown in FIGS. 3A and 3B and FIGS. 4A and 4B, the inner wall 142 of the container 140 is viewed from the device height direction (when the container 140 is viewed from above). A groove 142A is formed. As shown in FIG. 3B, the groove 142 </ b> A corresponds to a portion of the container 140 that contacts the contact member 130. For this reason, the contact member 130 rotates while contacting the groove bottom 142B of the groove 142A as the stirring member 120 rotates.

<< Operation of First Embodiment >>
Next, the operation of the main part (developing device 18) of the present embodiment will be described in comparison with comparative forms (comparative forms 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 Form 1]
The developing device of the comparative form 1 does not include the contact member 130. Further, in the developing device of the comparative form 1, the groove 142A is not formed in the container 140. Except for these points, the configuration is the same as that of the present embodiment.

  In the case of the developing device according to comparative embodiment 1, the liquid developer G accommodated in the container 140 adheres to the supply roll 112 and is pumped up from the container 140 as the supply roll 112 rotates. The amount of the liquid developer G pumped up is regulated by the regulating member 114 that is in contact with the supply roll 112. The liquid developer G that has passed through the part of the supply roll 112 that contacts the regulating member 114 is conveyed to the nip portion with the development roll 102 as the supply roll 112 rotates. On the other hand, the liquid developer G that has not passed through the portion of the supply roll 112 that contacts the regulating member 114 is dropped into the container 140 by the regulating member 114. Since a part of the toner T constituting the liquid developer G dropped in the container 140 is subjected to mechanical stress by the regulating member 114, the toner T tends to be aggregated in the container 140. In addition, the aggregate of the toner T is likely to precipitate in the container 140.

  A part of the liquid developer G conveyed to the nip portion with the developing roll 102 is supplied to the developing roll 102 by a supply electric field. Further, the remainder of the liquid developer G is not supplied to the developing roll 102 but returned to the container 140 as the supply roll 112 rotates. Part of the toner T constituting the liquid developer G returned into the container 140 is subjected to mechanical and electrical stress by the developing roll 102 and the supply roll 112, and the toner T It tends to be an aggregate. In addition, the aggregate of the toner T is likely to precipitate in the container 140.

  The liquid developer G supplied to the developing roll 102 is conveyed to a portion (nip portion) where the developing roll 102 and the photosensitive drum 12 face each other as the developing roll 102 rotates. A part of the liquid developer G is used to develop the latent image formed on the photosensitive drum 12 as a toner image by a developing electric field. On the other hand, the remaining liquid developer G is rotated with the rotation of the developing roll 102 and is removed from the developing roll 102 by the removing member 104. The removed liquid developer G is dropped into the container 140. A part of the toner T constituting the liquid developer G dropped into the container 140 is mechanically and electrically stressed by the developing roll 102 and the photosensitive drum 12, and mechanically by the developing roll 102 and the removing member 104. Under the stress, the toner T tends to be aggregated in the container 140. In addition, the aggregate of the toner T is likely to precipitate in the container 140.

<Mechanism of Aggregation of Toner T>
Here, the mechanism by which the aggregate of the toner T is generated when the liquid developer G is subjected to mechanical or electrical stress will be described with reference to FIG.

  The toner T of the present embodiment is charged positively in a stable state. Around the toner T, a negative polarity layer (electric double layer Te) is formed by a minute potential difference generated at the interface between the carrier oil O and the toner T. As shown in FIG. 5A, since the toners T are charged with positive polarity, the electric double layer Te formed around each toner T has negative polarity. Therefore, the repulsive force f acts on the electric double layer Te around each toner T. In this way, the dispersed state between the toners is maintained.

  However, when the toner T receives electrical or mechanical stress, the electric double layer Te formed around the toner T is broken. When the amount of the toner T in which the electric double layer Te is broken increases, the toner T in which the electric double layer Te is maintained easily aggregates in the toner T in which the electric double layer Te is broken. In this way, it is assumed that an aggregate of toner T is generated.

<Mechanism for easy aggregation of toner T aggregates>
Further, the mechanism that the aggregate of the toner T easily precipitates will be described with reference to FIGS. 5B and 5C.

  The viscosity of the liquid developer G varies greatly depending on the dispersion state of the toner T in the liquid developer G. A state in which the toner T is dispersed in the liquid developer G (for example, a state as shown in FIG. 5B), and a state in which an aggregate of the toner T is generated and aggregated (for example, as in FIG. 5B) Compare the current state). As shown in FIG. 5B, for example, the central toner T and the four toners T around it are interacting with each other (repulsive forces are mutually exerted). On the other hand, as shown in FIG. 5C, for example, if four toners T are aggregated to form an aggregate of two toners, the mutual relationship between the toners T results. The action (repulsive force exerted on each other) is reduced. For this reason, the viscosity of the toner T in the liquid developer G decreases. As a result, the aggregate of the toner T is likely to precipitate.

  Further, when the aggregate of the toner T precipitates on the inner wall of the container 140, the spiral body 120 </ b> B of the stirring member 120 cannot directly contact the aggregate of the toner T. For this reason, when the aggregate of the toner T that has settled on the inner wall of the container 140 for some reason is separated from the inner wall of the container 140 and stirred in the liquid developer G, it is pumped up to the supply roll 112, In some cases, the toner is supplied to the developing roll 102. As a result, the aggregate of the toner T adheres to the liquid developer G layer formed on the outer peripheral surface of the developing roll 102, and the aggregate of the toner T forms a toner image on the latent image formed on the photosensitive drum 12. As a result, the toner image is developed as a part of the toner image, and the density unevenness of the toner image occurs.

  On the other hand, in the case of the developing device 18 of this embodiment, as described in the comparative example 1, the aggregate of the toner T exists in the container 140, and the aggregate of the toner T is contained in the container 140. It settles on the inner wall 142.

  However, the developing device 18 of this embodiment includes the contact member 130. In the developing device 18 of this embodiment, the contact member 130 contacts the aggregate of toner T adhering to the inner wall 142 of the container 140 as shown in FIG. Is rotated between the inner wall 142 and the inner wall 142. For this reason, the aggregate of the toner T is easily dispersed.

  Therefore, according to the developing device 18 of the present embodiment, the adhesion of the aggregate of the toner T to the developing roll 102 is suppressed as compared with the developing device of the comparative form 1. Accordingly, in the developing device 18 of the present embodiment, the occurrence of spots of the liquid developer G due to the adhesion of the aggregates of the toner T to the developing roll 102 is suppressed.

  Further, in the developing device 18 of the present embodiment, a groove 142A is formed in the container 140. The contact member 130 is rotated while being in contact with the groove bottom 142B of the groove 142A.

  Here, the stirring member 120 conveys the liquid developer G in a predetermined direction (apparatus depth direction) while stirring the liquid developer G in the container 140. In this case, for example, the aggregate of the toner T that has settled on the inner wall 143C of the inner wall 142 of the container 140 that does not contact the contact member 130 is moved along with the transport of the liquid developer G. Thereafter, the aggregate of the toner T moved to the groove bottom 142B of the groove 142A is trapped in the groove 142A, so that the contact member 130 tends to stay in the groove 142A that contacts while rotating.

  Therefore, according to the developing device 18 of the present embodiment, the aggregate of the toner T is easily redispersed as compared with the developing device of the comparative form 1. Further, in the developing device 18 of the present embodiment, adhesion of toner T aggregates to the developing roll 102 is suppressed.

  Accordingly, according to the image forming apparatus 10 of the present embodiment, compared to the image forming apparatus provided with the developing apparatus of the comparative form 1, the liquid developer resulting from the adhesion of the aggregates of the toner T to the developing roll 102. Generation of G spots is suppressed.

[Comparison with comparative form 2]
In the developing device of Comparative Example 2, the contact member rotates without bending while being in contact with the groove bottom 142B of the groove 142A of the container 140. Except for these points, the configuration is the same as that of the present embodiment. Note that the developing device of comparative form 2 is included in the technical scope of the present invention.

  Since the contact member of the comparative form 1 does not bend even if it contacts the groove bottom 142B of the groove 142A, the contact member of the comparative form 2 rotates when contacting the toner T aggregate. The nip portion is not formed with the groove bottom 142B of the groove 142A. As used herein, the nip portion means a contact portion that the contact member forms with the groove bottom 142B in the rotation direction of the contact member.

  On the other hand, the contact member 130 of this embodiment is configured to rotate while being bent and contacting the groove bottom 142B of the groove 142A of the container 140. When the contact member 130 rotates in contact with the aggregate of the toner T, the contact member 130 forms a nip portion with the groove bottom 142B with the aggregate of the toner T interposed therebetween. Further, the contact member 130 of the present embodiment is configured to bend when the groove bottom 142B and the nip portion are formed. For this reason, the toner T constituting the aggregate of the toner T sandwiched between the contact member 130 and the groove bottom 142B is easier to roll at the nip portion than in the case of the comparative mode 2.

  Therefore, according to the developing device 18 of the present embodiment, the aggregate of the toner T is easily redispersed as compared with the developing device of the comparative form 2.

  Accordingly, according to the image forming apparatus 10 of the present embodiment, compared to the image forming apparatus provided with the developing apparatus of the comparative form 2, the image formation due to the occurrence of spots of the liquid developer G on the developing roll 102 is formed. Defects are suppressed.

<< Second Embodiment >>
Next, a second 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.

"Constitution"
The developing device 18A of the present embodiment includes a contact member 130A. In the contact member 130A, the conductive layer 130A1 is formed on the entire surface of the contact member 130 on the side contacting the groove bottom 142B of the groove 142A. The conductive layer 130A1 of this embodiment is an aluminum layer as an example. Further, the conductive layer 130A1 of the contact member 130A is grounded. Specifically, the conductive layer 130A1 is connected to the earth (or ground). Except for these points, the configuration is the same as that of the first embodiment.

<Action>
In the case of the present embodiment, the toner T aggregate is held between the contact member 130A and the groove bottom 142B of the groove 142A, while the toner T aggregate is in contact with the conductive layer 130A1 grounded to the ground. It is sandwiched and pressed by a nip formed between 130A and the groove bottom 142B. For this reason, the aggregate of the toner T is easily removed from the conductive layer 130A1.

Therefore, according to the developing device 18A of the present embodiment, it is easier to remove the aggregates of the toner T than a developing device that does not include the grounded contact member 130A. In addition, when the aggregate of the toner T is excessively charged (when overcharged), the charge amount after the toner T aggregate is neutralized is greatly reduced.
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 this embodiment, the description will be made using the reference numerals of the components as they are.

"Constitution"
In the developing device 18B of this embodiment, a conductive layer 142D is provided on the groove bottom 142B of the groove 142A. The conductive layer 142D of this embodiment is an aluminum layer as an example. The conductive layer 142D is grounded. Specifically, the conductive layer 142D is connected to the ground. Except for these points, the configuration is the same as that of the first embodiment.

<Action>
In the case of the present embodiment, the aggregate of the toner T is the aggregate of the toner T sandwiched between the contact member 130 and the conductive layer 142D, and the contact member 130 and the conductive layer 142D are in contact with the grounded conductive layer 142D. It is sandwiched and pressed by the nip formed in For this reason, the aggregate of the toner T is easily removed from the conductive layer 142D.

Therefore, according to the developing device 18B of the present embodiment, it is easier to remove the aggregate of the toner T than in the developing device in which the groove bottom is insulative. In addition, when the aggregate of the toner T is excessively charged (when overcharged), the charge amount after the toner T aggregate is neutralized is greatly reduced.
Other operations of the present embodiment are the same as those of the first embodiment.

<< Fourth Embodiment >>
Next, a fourth 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.

"Constitution"
The developing device 18C of this embodiment includes a contact member 130A. In the developing device 18C of the present embodiment, a conductive layer 142D is provided on the groove bottom 142B of the groove 142A. The conductive layer 130A1 and the conductive layer 142D of the contact member 130A are grounded. Except for these points, the configuration is the same as that of the first embodiment.

<Action>
In the case of the present embodiment, both the developing device 18A of the second embodiment and the developing device 18B of the third embodiment have the action.
Other operations of the present embodiment are the same as those of the first embodiment.

«Fifth embodiment»
Next, a fifth 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.

"Constitution"
The developing device 18D of this embodiment includes a contact member 130A. In the developing device 18D of the present embodiment, the conductive layer 142D is provided on the groove bottom 142B of the groove 142A. A potential difference is applied to the conductive layer 130A1 and the conductive layer 142D of the contact member 130A by the power supply 170. Further, a resistance layer 130A2 is provided in a contact portion of the conductive layer 130A1 with the conductive layer 142D. For this reason, a short circuit between the conductive layer 130A1 and the conductive layer 142D is prevented. In the present embodiment, the volume resistivity of the resistance layer 130A2 is set to 10 ⁷ Ωcm to 10 ⁸ Ωcm as an example. Moreover, the applied voltage of the power supply 170 is 100V-300V as an example. Except for these points, the configuration is the same as that of the first embodiment.

<Action>
In the developing device 18D of this embodiment, the aggregate (positive polarity) of the toner T on the conductive layer 142D is attracted to the conductive layer 130A1 of the contact member 130A by the electric field between the conductive layer 142D and the conductive layer 130A1.

Therefore, according to the developing device 18D of the present embodiment, the aggregate of the toner T can be easily redispersed compared to the developing device in which no potential difference is given between the groove bottom and the contact member.
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 the first embodiment, the image forming unit 26 has been described as including the developer replenishing device 150. However, if the liquid developer G in the container 140 is insufficient, the image forming apparatus 10 may not include the developer replenishing device 150 as long as the liquid developer G can be replenished by some method.

  Further, in the first embodiment, one end side in the longitudinal direction of the contact member 130 has been described as being attached to the shaft 120 </ b> A of the stirring member 120. However, the contact member 130 may not be attached to the shaft 120 </ b> A of the stirring member 120 as long as it can rotate with the stirring member 120.

  In the fourth embodiment, the conductive layer 130A1 and the conductive layer 142D of the contact member 130A have been described as being grounded. However, it is sufficient that both are grounded, and the conductive layer 142D may be grounded via the conductive layer 130A1 by grounding the conductive layer 130A1. Alternatively, the conductive layer 142D may be grounded, and the conductive layer 130A1 may be grounded via the conductive layer 142D.

  Further, in the fifth embodiment, the conductive layer 130A1 and the conductive layer 142D of the contact member 130A are described as being given a potential difference by the power source 170. According to FIG. 9, this potential difference is a potential difference based on a DC voltage. However, the power source 170 is a power source composed of a DC power source and an AC power source, and the potential difference between the conductive layer 130A1 and the conductive layer 142D is changed to a DC voltage. It is good also as a potential difference based on the voltage superimposed. In this case, each toner T constituting the aggregate of the toner T between the conductive layer 130A1 and the conductive layer 142D can be vibrated and redispersed based on an alternating electric field.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 12 Photosensitive drum (an example of an image holding body)
14 charging device 16 exposure device 18 developing device 18A developing device 18B developing device 18C developing device 18D developing device 20 transfer unit (an example of a transfer device)
102 Developing roll (an example of a developing member)
112 Supply roll (an example of a supply member)
114 Regulating member 120 Stirring member 130 Contact member 130A Contact member 140 Housing 142A Groove 142B Groove bottom G Liquid developer O Carrier oil P Medium T Toner

Claims (6)

A developing member that develops a latent image formed on the image carrier as a toner image with a liquid developer containing toner and carrier oil while rotating about its own axis;
A container for containing a liquid developer;
A supply member that is rotatably provided so as to be axially aligned with the developing member, and that partially rotates in the liquid developer of the container and supplies the liquid developer to the developing member while rotating about its own axis ,
A regulating member that is disposed on the upper side of the container, regulates the amount of the liquid developer, and returns the liquid developer removed by the supply member into the container;
An agitation member disposed in a liquid developer accommodated in the container and transported in a predetermined direction while rotating around its own axis;
A contact member attached to the stirring member and rotating while contacting the inner wall of the container as the stirring member rotates;
A developing device comprising: The contact member rotates while being bent and contacting the inner wall of the container as the stirring member rotates.
The developing device according to claim 1. On the inner wall of the container, a groove is formed when the container is viewed from above,
The contact member rotates while contacting the groove bottom of the groove as the stirring member rotates.
The developing device according to claim 1 or 2. The contact member or the groove bottom of the groove is conductive and grounded.
The developing device according to claim 1. The contact member and the groove bottom of the groove are conductive and electrically connected to each other.
The developing device according to claim 1. An image carrier,
A charging device for charging the image carrier;
An exposure device that exposes an image carrier charged by the charging device to form a latent image; and
The developing device according to claim 1, wherein the latent image formed on the image holding member is developed with a liquid developer as a toner image.
A transfer device for transferring a toner image developed on the image holding member to a transfer member;
An image forming apparatus.

Images