JP2006030719A - Developing apparatus and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem in which aggregated toner particles remaining on a developer carrier are caught in the edge part of a cleaning blade arranged in contact with the surface of the developer carrier, and the surface of a developing roller is damaged as a result. <P>SOLUTION: The developing apparatus 4 is provided with the developing roller 12 for carrying liquid developer 10, and the cleaning blade 23 for removing the liquid developer 10 remaining on the surface of the developing roller 12 after a developing process, further, an auxiliary removing means 24 for reducing the cohesive force of the liquid developer 10 on the developer carrier 12 is arranged upstream of the cleaning blade 23 in the developer roller rotating direction. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a developing device and an image forming apparatus, and more particularly to a developing device and an image forming apparatus using a liquid developer.

  As an image forming apparatus, the surface of the photoconductor is uniformly charged by a charging unit, and the surface of the photoconductor is exposed according to image data by an optical writing unit to form an electrostatic latent image. There is an electrophotographic system in which a visible image is developed and then transferred to a transfer member (including an intermediate transfer member).

In such an image forming apparatus, as a developing device for visualizing an electrostatic latent image, for example, a high-viscosity and high-concentration liquid developer is used as disclosed in Patent Documents 1, 2, and 3. Some use a liquid developing device.
JP 7-152254 A Japanese Patent Laid-Open No. 7-209922 JP 7-219355 A

  This liquid developing apparatus is a liquid developer having a high viscosity of 50 to 10,000 mPa · s, in which a toner as a visualized particle is dispersed at a high concentration in a developer solvent made of an insulating liquid such as dimethylpolysiloxane oil. Use the agent. Then, the liquid developer stored in the storage tank is applied to the developing roller and the developing belt with a uniform thickness, and the liquid developer thin layer applied to the developing roller and the developing belt passes through the developing region in the vicinity of the photoreceptor. When the electrostatic latent image on the photosensitive member is developed with the toner of the thin layer of the liquid developer to form a toner image, the liquid developer remaining on the developing roller or the developing belt that has passed through the developing area is scraped off with a blade. Remove and collect in storage tank.

  By the way, the liquid developer used for this image formation is formed by dispersing a solid content (toner) composed of a resin and a pigment in an insulating liquid (carrier liquid) as described above, and is charged during development. Since the toner moves in the insulating liquid by electrostatic force to develop the electrostatic latent image, the developing efficiency is improved as the moving distance of the charged toner is shorter.

  Therefore, in order to increase the development efficiency, a thin layer of a micron unit of liquid developer is formed on a developer carrier such as a developing roller, and the thinned liquid developer is brought into contact with the photoreceptor 1 for development. It is preferable to do. This is particularly noticeable when a high-viscosity liquid developer having a viscosity of 50 to 10,000 mPa · s is used.

  Thus, when developing with a thin layer of liquid developer, the concentration is determined by the thickness of the layer of the liquid developer. It is necessary to form a stable and uniform thin layer of liquid developer on the body.

Therefore, conventionally, as disclosed in Patent Document 4, using a coating roller (anilox roller) whose surface is regularly engraved, a predetermined amount of liquid developer is carried on the coating roller, The developing roller, which is a developer carrying member, is brought into direct contact with the coating roller, and the developing roller is rotated at a peripheral speed equal to or higher than the peripheral speed of the coating roller so that the contact surface moves in the direction opposite to the coating roller. The liquid developer is transferred to the developing roller, and the engraving pattern on the coating roller is leveled during transfer to form a thin layer having a uniform thickness on the developing roller.
Japanese Patent Laid-Open No. 11-265122

  However, when the application roller is rotated so that it directly contacts the developing roller and moves in the opposite direction (the rotation direction is the same), the surface of the developing roller is always larger than the engraving pattern on the surface of the applying roller. Since contact is made with a linear velocity, there is a disadvantage that the surface of the developing roller is scratched by friction and the life is shortened.

  In the above case, in a coating apparatus that transfers the liquid developer by bringing the coating roller and the developing roller into direct contact with each other, the developing roller as a developer carrying member is scratched or the durability of the developing roller is reduced. Therefore, it is difficult to produce a highly durable part because the selection range of the forming member is narrow.

  The specifications of the developing roller are as follows: (1) low hardness for forming a developing nip with the photoconductor, (2) at least the surface being a conductive material for bias application, (3) Have mechanical strength of the surface for abrasion resistance against the coating roller, (4) have mechanical strength of the surface for abrasion resistance of the cleaning blade, (5) uniform coating Therefore, strict characteristics such as having smoothness are required, so that it is difficult to manufacture highly durable parts.

  Among these, the requirements of (3) and (4) are deeply related to the durability of the developing roller, and the life of the developing roller is determined depending on how this is satisfied. For example, the surface of the developing roller is electrically conductive. Even when a PFA tube is used, the durable life of the developing roller is only about 50,000 printed sheets.

Further, as disclosed in Patent Document 5, as a liquid developing device, a liquid toner in a state where charged toner particles are aggregated by applying an electric field to a liquid developer attached to the surface of the developing roller before development. An electric field applying roller for forming a layer; and a cleaning roller for removing the liquid developer remaining by applying an electric field to the liquid developer remaining on the surface of the developing roller from the surface of the developing roller. There has been proposed a developing apparatus in which development is performed by pressing a developing roller holding a liquid toner layer in a state of being pressed against a charge carrier on which an electrostatic latent image is formed.
Japanese Patent Application Laid-Open No. 9-211993

  However, as described above, in a developing device that performs development by forming a thin layer of the liquid developer on the developing roller with the application roller, the aggregated toner particles (lamp) remaining on the developer carrier after development ) Is sandwiched between the edges of the cleaning blade disposed in contact with the surface of the developer carrying member, and the surface of the developing roller is damaged by rotating the developing roller while the toner particles are pressed against the surface of the developing roller. There are challenges.

  Further, in the developing device described in the above-mentioned Patent Document 5, the liquid developer that remains after development is used to develop after compressing (aggregating) by applying an electric field to the liquid developer before development. The cohesive force of the toner particles in the toner is several times stronger than the case where the compression before the development is not performed, and the remaining liquid developer can be surely removed only by the cleaning roller to which the opposite charge is applied. There is a problem that it is difficult.

  The present invention has been made in view of the above problems, and a developing device that can reliably remove the residual liquid developer without damaging the surface of the developer carrying member, and a stable developing device provided with the developing device. An object is to provide an image forming apparatus capable of forming a high quality image.

  In order to solve the above-described problems, the developing device according to the present invention includes a removal assisting unit that weakens the cohesive force of the liquid developer on the developer carrier on the upstream side of the removing unit that removes the liquid developer. It was set as the composition.

  Here, the removal assisting means is preferably an electric field forming means that weakens the cohesive force by applying an electric field to the liquid developer on the developer carrying member. In this case, the electric field forming means can be an electrode member or a roller member arranged to face the surface of the developer carrying member, and in these cases, the electric field forming means forms an electric field containing an AC component. Is preferred.

  The removal assisting means is preferably a shearing means that weakens the cohesive force by applying a mechanical shearing force to the liquid developer on the developer carrier. In this case, the shearing means can be a brush arranged in contact with the surface of the developer carrying body, or a roller arranged so that the peripheral surface thereof can move relative to the surface of the developer carrying body. Furthermore, it is preferable that the roller is formed of a porous material containing bubbles therein. In these cases, the shearing means is preferably arranged so as to be swingable in the axial direction of the developer carrier.

  Further, it is preferable that the removal assisting unit is a unit that applies an electric field to the liquid developer on the developer carrying member and weakens the cohesive force by applying a mechanical shearing force.

  Further, it is preferable to have means for supplying the carrier liquid constituting the liquid developer to a region where the cohesive force of the liquid developer is weakened by the removal assisting means. In this case, after development, it is preferable to remove and recover the excess carrier liquid adhering to the latent image carrier and supply it to an area where the cohesive force of the liquid developer is weakened.

  Further, it is preferable that the removing means also serves as a member for applying the liquid developer to the developer carrying member. In addition, it is preferable that a means for applying an electric field to the liquid developer applied to the developer carrier before development is provided.

  The image forming apparatus according to the present invention includes the developing device according to the present invention.

  According to the developing device of the present invention, the liquid developer is provided on the upstream side of the removing member for removing the liquid developer, since the removal assisting means for weakening the cohesive force of the liquid developer on the developer carrying member is provided. The remaining liquid developer can be reliably removed without damaging the surface of the developer carrying member by removing the cohesive force of the developer carrying member by removing means, and the durability of the developer carrying member can be improved. .

  According to the image forming apparatus of the present invention, since the liquid developer developing device according to the present invention is provided, a high-quality image can be stably formed.

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic configuration diagram of a main part of an image forming apparatus including a developing device according to the first embodiment of the present invention.
This image forming apparatus is an image forming apparatus having a printer configuration, and a charging charger (or a charging roller or the like) is provided around a drum-shaped photoconductor 1 which is a latent image carrier using amorphous Si, OPC or the like. Two chargers 2A and 2B used, an optical writing device 3 using an LED array (or a laser scanning optical system or the like), a developing device 4 according to the present invention, a transfer device 5, and a static elimination device using a static elimination lamp. 6. A cleaning device 7 using a cleaning blade is disposed. By using a photoconductor 1 made of amorphous silicon, the photoconductor 1 can exhibit a mechanical strength superior to that of an organic photoconductor (OPC), can extend its life, and maintain stable image quality. can do.

  In this image forming apparatus, the photosensitive member 1 is rotated in the direction of the arrow at a constant speed by driving means such as a motor (not shown), and the surface of the photosensitive member 1 is uniformly charged in the dark by the chargers 2A and 2B. Then, exposure is performed by irradiating laser light from the optical writing device 3 according to the recorded image, and an electrostatic latent image corresponding to the recorded image is formed on the surface of the photoreceptor 1. In addition, the arrow in each figure means a rotation direction or a moving direction.

  The developer (toner) is applied to the electrostatic latent image on the surface of the photosensitive member 1 by the developing device 4 according to the present invention, and the toner image is transferred to the intermediate transfer roller 51 of the transfer device 5. The image is transferred from the transfer roller 51 to the transfer paper 9 conveyed in the direction of the arrow by the paper feed roller 8 while being pressed by the secondary transfer roller 52. As the transfer device 5, for example, a device that performs transfer by an electrostatic roller method, a corona discharge method, an adhesive transfer method, a thermal transfer method, or the like can be used, and the intermediate transfer roller 51 and the secondary transfer roller can be used. Cleaning blades 53 and 54 are in contact with the surface of 52.

  The transfer paper 9 onto which the toner image has been transferred passes through a fixing device (not shown) and is fixed, and then is discharged outside the apparatus. As the fixing device, for example, a device that performs a fixing process such as a thermal fixing method, a solvent fixing method, a UV fixing method, and a pressure fixing method can be used.

  On the other hand, after the transfer, the photosensitive member 1 is removed from the residual potential by the static eliminator 6 and the residual toner is removed by the cleaning device 7 to prepare for the next image formation.

Next, details of the developing device 4 of the image forming apparatus will be described with reference to FIG. FIG. 2 is an enlarged explanatory view of a main part of the developing device 4.
The developing device 4 is attached to the surface of the photoconductor 1 on the downstream side of the developing roller 12, a developer containing tank 11 that contains the liquid developer 10 therein, a developing roller 12 that is a developer carrying member. Sweep rollers 13 </ b> A and 13 </ b> B for scraping off the developer (referred to as “sweep roller 13” when not distinguished) and an application roller 21 for applying the liquid developer 10 to the development roller 12 are provided.

  The liquid developer 10 is not a low-viscosity (about 1 cSt), low-concentration (about 1%) liquid developer using Isopar (registered trademark) as a carrier, which is generally used in the past, but a high-viscosity, high-concentration liquid. Developer. As the viscosity and density range of the developer, for example, a viscosity of 50 to 10,000 mPa · s and a density of 5% to 40% are used. As the carrier liquid, a highly insulating material such as silicone oil, normal paraffin, Isopar M (registered trademark), vegetable oil or mineral oil is used. Volatile and non-volatile can be selected according to the purpose, and the particle size of the toner can be selected from submicron to about 6 μm according to the purpose.

  The liquid developer 10 is fed from a not-shown adjustment tank to the developer storage tank 11 in the developing device 4 by the stirring / conveying screw 15 and stirred by the stirring / conveying screw 15.

  The developing roller 12 and the sweep roller 13 are each provided with an elastic body layer formed of urethane rubber or the like having conductivity on the outer peripheral surface thereof. The surface hardness of the elastic layer is preferably 50 degrees or less in terms of JIS-A hardness so that a nip can be efficiently formed with the photoreceptor 1. The material of the elastic layer is not limited to urethane rubber, but may be any material that has conductivity and does not swell or dissolve with the carrier liquid or developer of the liquid developer. Further, the developing roller 12 and the sweep roller 13 have a surface having a 10-point average surface roughness Rz of 5 μm or less by using a coating or a tube.

  The developing roller 12 and the sweep roller 13 may be configured such that the surfaces thereof are conductive and do not swell or dissolve with the liquid developer, and the liquid developer does not contact the inner layer. For example, the material of the inner layer is not limited to the above-mentioned conductivity and swelling and dissolution, and may be elastic. At this time, it is necessary to apply the developing bias voltage to the developing roller 12 and the sweep bias voltage to the sweep roller 13 from the surface, not from the shaft of the developing roller 12 or the sweep roller 13.

  In addition, an elastic body layer may be provided on the surface of the photosensitive member 1 instead of an elastic body layer provided on the developing roller 12 or the sweep roller 13 side.

  The developing roller 12 and the sweep roller 13 are brought into contact with the photoreceptor 1 with an appropriate pressure, respectively, and elastic layers of the rollers 12 and 13 are elastically deformed to form a developing nip and a removal nip, respectively. ing. In particular, by forming the developing nip portion, it is possible to ensure a certain developing time for the developer toner to move and adhere to the photoreceptor 1 by the developing electric field in the developing region.

  Moreover, the nip width which is the width | variety of the surface moving direction in each nip part can be adjusted by adjusting a contact pressure. Each nip width is set to a numerical value equal to or greater than the product of the linear speed of each of the rollers 12 and 13 and the development time constant. Here, the development time constant is the time required until the development amount is saturated, and is obtained by dividing the necessary minimum nip width by the process speed. For example, if the required minimum nip width is 5 mm and the process speed is 500 mm / sec, the development time constant is 10 msec.

  Further, cleaning blades 16A and 16B for removing the developer on the surface of the sweep roller 13 (referred to as “cleaning blade 16” when not distinguished) are provided. The cleaning blade 16 is composed of a metal blade or a rubber blade and is in contact with the surface of the sweep roller 13. A roller may be used instead of the blade.

In the developing device 4, a thin layer of the liquid developer 10 is formed on the developing roller 12 by the application roller 21 during the developing operation. At this time, the liquid developer 10 is applied from the coating roller 21 to the developing roller 12 so that the pigment content in the toner carried per 1 cm ² of the surface of the developing roller 12 is 3 μg or more and 60 μg or less. Therefore, the thin layer of the liquid developer was made to have a thickness of 3 to 12 μm.

That is, when the coating thickness of the liquid developer is such that the pigment content in the toner carried per 1 cm ^{2 of the} surface of the developing roller 12 is less than 3 μg, a sufficient amount of pigment is applied on the photoreceptor 1. There is a possibility that the image density of the image portion becomes thin without moving to the image portion of the formed latent image. On the other hand, when the pigment content in the toner carried per 1 cm ^{2 on the} surface of the developing roller 12 is larger than 60 μg, excess toner remains on the background after development, and the sweep roller 13 removes the toner. May be incomplete.

  The thin layer of the liquid developer 10 formed on the surface of the developing roller 12 develops the latent image on the photosensitive member 1 when passing through the developing nip formed by the photosensitive member 1 and the developing roller 12. . That is, in the image portion, the toner in the liquid developer 10 moves onto the photosensitive member 1, and in the background portion (non-image portion), the developing roller is caused by an electric field formed by the developing bias potential and the potential of the photosensitive member 1. 12 The toner moves to the surface side and the toner does not adhere to the background portion, so that the electrostatic latent image is developed.

  The developing portion of the photosensitive member 1 developed by the developing roller 12 faces the sweep roller 13 and does not move to the surface of the developing roller 12 at the background portion, but remains on the photosensitive member 1 side and causes toner (which causes fogging). Hereinafter, the “fog toner” is swept (cleaned) by the sweep roller 13.

  As described above, the sweep roller 13 is disposed downstream of the developing roller 12 in the rotation direction of the photosensitive member 1 and pressed against the photosensitive member 1 so as to sandwich the developed toner layer. The surface of the sweep roller 13 removes fog toner from the background while moving at substantially the same speed as the surface of the photoreceptor 1.

  The liquid developer 10 removed by the sweep roller 13 is removed by the cleaning blade 16 in order to maintain the sweep performance, collected in an adjustment tank, and sent again into the development unit after adjusting the density. It is like that.

  In the adjustment tank, a part of the agitating / conveying screw 15 described above, concentration detection means and liquid amount detection means (not shown) are provided, and the concentration and liquid amount are detected with the concentration in the tank uniform. The density is adjusted by replenishing new liquid developer or replenishing carrier. The supply amount of the liquid developer into the developing device 4 from here is set so as to be slightly larger than the use amount of the liquid developer, and the overflow amount is returned to the adjustment tank. The agent always circulates.

  Next, the application roller 21 for applying the liquid developer 10 to the surface of the developing roller 12 to form a thin layer will be described.

  As shown in FIG. 3, the application roller 21 is a roller having a fine engraving groove 21a formed in a uniform pattern on the surface thereof. As the shape of the engraving groove 21a, an oblique engraving groove 21a1 as shown in FIG. 4 (a), a pyramid engraving groove 21a2 as shown in FIG. 4 (b), and a lattice type as shown in FIG. 4 (c). The sculpture grooves 21a3 can be formed.

  The application roller 21 carries the liquid developer 10 contained in the developer containing tank 11 on the surface and rotates in the direction indicated by the arrow in FIG. 2 while engraving the liquid developer 10 carried on the surface. The surplus protruding from the upper part of the groove 21 a is scraped off by a doctor blade 22 which is a regulating member arranged in contact with the application roller 21 and is measured, and the liquid developer 10 after the measurement is applied to the application roller 21. A uniform thin layer of the liquid developer 10 is formed on the developing roller 12 by coating on the surface of the developing roller 12 that rotates in the direction indicated by the arrow in the same direction as the rotation direction (the reverse direction on the contact surface). Yes.

  In the present embodiment, the oblique engraving groove 21a1 is used as the engraving groove 21a of the application roller 21 for reasons such as good transferability. Further, although the doctor blade 22 is used as a regulating member that contacts the coating roller 21 and measures the amount of the liquid developer 10 applied, it is also possible to use a doctor roller as a similar regulating member.

Next, the cleaning means for removing the liquid developer remaining on the developing roller 12 in the developing device 4 after development will be described.
In the developing device 4, a cleaning blade 23 that is a removing unit that contacts the surface of the developing roller 12 from the direction opposite to the rotation direction and removes the liquid developer 10 remaining on the surface of the developing roller 12, The cohesive force of the liquid developer 10 remaining on the surface of the developing roller 12 (meaning “cohesive force of toner particles in the liquid developer”) is weakened upstream of the cleaning blade 23 in the rotation direction of the developing roller 12. The removal assisting means 24 constitutes a cleaning means 25 for removing the liquid developer 10 remaining on the surface of the developing roller 12 after development.

  Since the cleaning means 25 is configured in this manner, the liquid developer 10 remaining on the surface of the developing roller 12 after development is reduced in the cohesive force of the toner particles by the removal assisting means 24 and then the surface of the developing roller 12 by the cleaning blade 23. It is scraped off and removed.

  When the liquid developer 10 remaining on the surface of the developing roller 12 is scraped off by the cleaning blade 23, the cohesive force of the remaining liquid developer 10 is weakened by the removal assisting means 24, so that the liquid developer 10 is agglomerated at the tip of the cleaning blade 23. The clogging of the liquid developer 10 is prevented, the liquid developer 10 can be reliably removed without damaging the surface of the developing roller 12, and the durability of the developing roller 12 can be improved.

  That is, referring also to FIG. 5, in the developing nip formed by the photoreceptor 1 and the developing roller 12, the toner in the carrier liquid 10b is contained in the thin layer of the liquid developer 10 formed on the surface of the developing roller 12. The particles 10a are in a dispersed state. Here, when the image portion of the photoreceptor 1 faces the developing roller 12, the toner particles 10 a in the liquid developer 10 move toward the photoreceptor 1, and the carrier liquid 10 b remains on the developing roller 12. On the other hand, when the non-image portion (background portion) of the photoconductor 1 faces the developing roller 12, the toner particles 10a in the liquid developer 10 do not move to the photoconductor 1 side depending on the developing bias potential and the photoconductor potential. An electric field (developing electric field) is formed between the photosensitive member 1 and the developing roller 12 in a direction to draw the toner particles 10a in the liquid developer 10 toward the developing roller 12, and most of the toner particles 10a are affected by the electric field. Not only remains on the developing roller 12, but also moves to the surface side of the developing roller 12 to be compressed (becomes aggregated toner particles 10b ').

  Thus, since the density of the toner particles 10a of the liquid developer 10 remaining on the developing roller 12 is different between the image portion and the non-image portion, the liquid development for the next image formation is performed on the developing roller 12 as it is. When the agent 10 is applied, a ghost appearing on the next image is generated by reversing the previous image trace. Therefore, it is necessary to remove the liquid developer 10 remaining on the developing roller 12 after development.

  At this time, as shown in FIG. 6, if the liquid developer 10 containing the toner particles 10 a is removed only by the shearing force of the cleaning blade 23 brought into contact with the surface of the developing roller 12, the non-image portion of the developing roller 12 is removed. The remaining liquid developer 10 is compressed to the developing roller 12 side (aggregated toner particles 10a ′) and is difficult to be removed from the surface of the developing roller 12, so that the tip of the cleaning blade 23 The aggregated toner particles 10a ′ are clogged between the surface 23a and the surface of the developing roller 12, and the surface of the developing roller 12 is damaged by the rotation of the developing roller 12 in this state.

  In this case, if the contact pressure of the cleaning blade 23 is increased in order to increase the removal effect, the frictional force between the developing roller 12 and the cleaning blade 23 increases, which becomes a secondary factor that damages the surface of the developing roller 12.

  Therefore, as described above, the removal assisting means 24 for weakening the cohesive force of the toner particles 10a of the liquid developer 10 is provided on the upstream side in the rotation direction of the developing roller 12 of the cleaning blade 23, and as shown in FIG. By weakening the cohesive force of the toner particles 10a of the liquid developer 10 in advance (by a dispersed state) by the auxiliary means 24 and then removing the liquid developer 10 by the cleaning blade 23, the surface of the developing roller 12 can be reliably damaged. Can be removed.

  In this way, the removal means is provided with a removal assisting means for weakening the cohesive force of the liquid developer on the upstream side in the rotation direction of the developer carrying member, and after the cohesive force of the liquid developer (toner particles) is weakened, By removing the liquid developer, the liquid developer that remains reliably while reducing damage to the surface of the developer carrier caused by clogging of the liquid developer aggregated between the removing means and the surface of the developer carrier. The developer can be removed, and the durability of the developer carrier is improved.

Next, a second embodiment of the present invention will be described with reference to FIG. In addition, FIG. 8 is explanatory drawing of the removal assistance means in the same embodiment.
In this embodiment, as a removal assisting means for weakening the cohesive force of the toner particles 10 a of the liquid developer 10 remaining on the surface of the developing roller 12 on the upstream side in the rotation direction of the developing roller of the cleaning blade 23, A charging charger 26 as an electric field forming means for applying an electric field.

  The charging charger 26 weakens the agglomeration force between the agglomerated toner particles 10 a ′ by forming an electric field that discharges charges having a polarity opposite to the polarity of the charged toner particles 10 a in the liquid developer 10.

  With this configuration, as shown in FIG. 8, when the toner particles 10a ′ aggregated in the liquid developer 10 remaining on the surface of the developing roller 12 pass through the region facing the charging charger 26, the reverse polarity charges are applied. Then, it moves in the direction away from the surface of the developing roller 12 to change from the compressed state to the dispersed state, and the cohesive force between the toner particles 10a is weakened. Therefore, the liquid developer 10 in which such toner particles 10a are dispersed can be removed by the cleaning blade 23 without the toner particles 10a clogging the tip.

  As described above, by using the electric field forming means that weakens the cohesive force by applying an electric field to the liquid developer on the developer carrier as a removal assisting means for weakening the cohesive force of the toner particles of the liquid developer, With the configuration, the agglomerated toner particles can be easily separated from the surface of the developing roller to be dispersed to weaken the aggregating force.

Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 9 is an explanatory view of the main part of the removal assisting means in the same embodiment.
In the present embodiment, an electrode member 27 facing the developing roller 12 is provided as an electric field forming unit that is a removal assisting unit provided on the upstream side of the cleaning blade 23 described above, and the developing roller 12 is developed with respect to the electrode member 27. An electric field is applied to the liquid developer 10 by applying a bias voltage Vc having the same polarity as the developing bias voltage Vb applied from the bias power supply 30 and lower than the developing bias voltage Vb from the bias power supply 31.

  Here, when the electrode member 27 is provided so as to face the surface of the developing roller 12, a non-contact type in which a fine gap is maintained between the developing roller 12 and the electrode member 27 may be employed. In view of the vibration during rotation of the developing roller 12 and the like, it is difficult to stably maintain a fine gap, and there is a possibility that a stable electric field cannot be formed.

  On the other hand, it is possible to use a contact type in which the electrode member 27 is brought into contact with the surface of the developing roller 12 at a predetermined pressure. In this case, in order to maintain the developing bias voltage applied to the developing roller 12, It is preferable to cover the surface of the electrode member 27 in contact with the developing roller 12 with a layer having a high resistance value, or to use a material having a medium resistance value instead of a conductor as the material of the electrode member 27 itself.

  Here, specifically, the electrode member 27 is pressed and brought into contact with the surface of the developing roller 12, and at least the surface of the electrode member 27 in contact with the surface of the developing roller 12 has a medium resistance value in which carbon is dispersed. The structure is covered with a sheet.

  With this configuration, as shown in FIG. 9, when the toner particles 10 a ′ aggregated in the liquid developer 10 remaining on the surface of the developing roller 12 pass through a region facing the electrode member 27, the developing roller 12. Is moved away from the surface of the toner and moved to the electrode member 27 side having a low bias potential Vc, so that the compressed state is changed to the dispersed state, and the cohesive force between the toner particles 10a is weakened. Therefore, the liquid developer 10 in which such toner particles 10a are dispersed can be removed by the cleaning blade 23 without the toner particles 10a clogging the tip.

  As described above, even if an electrode member for applying an electric field to the surface of the developing roller to weaken the cohesive force of the liquid developer is provided, the same effect as that of the above-described embodiment can be obtained.

  However, when an electric field that attracts the toner particles 10 a is formed on the electrode member 27, the toner particles 10 a attracted on the electrode member 27 may not move and may accumulate, and the surface of the electrode member 27 may be deposited. It is preferable to provide means for removing the deposited toner particles.

Next, a fourth embodiment of the present invention will be described with reference to FIGS. FIG. 10 is an explanatory view of the removal assisting means in the embodiment, and FIG. 11 is an explanatory view for explaining the drive mechanism of the electric field roller which is the removal assisting means.
In the present embodiment, an electric field forming unit that is a removal assisting unit provided on the upstream side of the cleaning blade 23 described above is provided with an electric field roller 32 that is a roller member facing the developing roller 12. A bias voltage Vc having the same polarity as the developing bias voltage Vb applied from the developing bias power supply 30 to the developing roller 12 and lower than the developing bias voltage Vb is applied from the bias power supply 31 to apply an electric field to the liquid developer 10.

  When the electric field roller 32 is formed of a conductor such as a metal roller in order to apply a bias voltage, a surface layer (resistance layer) having a predetermined resistance value on the surface thereof, as in the case of the third embodiment. It is necessary to provide. Specifically, a method of providing a coat layer having an appropriate resistance value, covering with a tube, or performing a surface treatment such as anodization can be used.

  In this case, in order to make it difficult for toner particles to adhere to the surface of the electric field roller 32, the surface layer (resistive layer) is preferably formed of a material having a low surface energy, and particularly includes at least a fluorine-based resin. preferable. Specifically, polytetrafluoroethylene (TFE Teflon (registered trademark)), fluoropolymer resins such as FEP, PFA, PTFE, and PVDF, and solvents containing these particles (for example, Lumiflon (registered trademark) manufactured by Asahi Kasei) Etc.) and the surface of the electric field roller 32 may be coated or covered with a tube material formed of these materials.

  Here, the drive mechanism of the electric field roller 32 will be described with reference to FIG. The simplest method for driving the electric field roller 32 is to rotate it with respect to the developing roller 12. However, the presence of the liquid developer 10 between the rollers 12 and 32 may cause slippage. Therefore, it is preferable to forcibly drive the electric field roller 32.

  Therefore, in this embodiment, as shown in FIG. 11, a drive gear 35 is provided on a drive shaft 34 rotated by a drive motor 41 that rotationally drives the developing roller 12, and a driven gear 36 is engaged with the drive gear 35. The rotation of the driven gear 36 is transmitted to the rotating shaft 38 of the electric field roller 32 via the one-way clutch 37.

  In this case, the rotation direction of the electric field roller 32 does not hinder the liquid developer 10 from passing between the developing roller 12 and the electric field roller 32, as shown in FIG. The surface of is moved in the same direction. Further, regarding the moving speeds of the respective surfaces of the developing roller 12 and the electric field roller 32, it is possible to make a difference in linear speed, but here the speed is set to be substantially constant.

  However, since it is difficult to make the movements of the surfaces of the developing roller 12 and the electric field roller 32 completely coincide with each other, the number of teeth of the driving gear 35 and the driven gear 36 is set so that the speed on the electric field roller 32 side is slower than the developing roller 12. And the driven gear 36 and the electric field roller 32 so as to transmit the driving force only in the driving direction as described above, in order to reduce the burden on the driving system due to the speed difference between the rollers 12 and 32. A one-way clutch 37 is incorporated between the two.

  With this configuration, as shown in FIG. 10, when the toner particles 10 a ′ aggregated in the liquid developer 10 remaining on the surface of the developing roller 12 pass through a region facing the electric field roller 32, the developing roller 12. Is moved away from the surface of the toner and moved to the electric field roller 32 side having a low bias potential Vc, the compressed state is changed to the dispersed state, and the cohesive force between the toner particles 10a is weakened. Therefore, the liquid developer 10 in which such toner particles 10a are dispersed can be removed by the cleaning blade 23 without the toner particles 10a clogging the tip.

  In this case, if the electric field formed by the electric field roller 32 to attract the toner particles 10a ′ is too strong, the toner particles 10a are compressed and aggregated on the electric field roller 32 side. The electric field generated by the bias voltage Vc applied to the roller 32 is preferably the same or weaker than the electric field when the toner particles 10a are compressed to the developing roller 12 side.

  Thus, even when a roller member for applying an electric field to face the surface of the developing roller to weaken the cohesive force of the liquid developer is provided, the same operational effects as those of the above-described embodiments can be obtained.

Next, a fifth embodiment of the present invention will be described with reference to FIG. In addition, FIG. 12 is explanatory drawing of the removal assistance means in the same embodiment.
In the present embodiment, an AC bias power supply 40 is connected in series with a DC bias power supply 31 to the electric field roller 32 in the fourth embodiment, and a bias voltage Vd in which an AC component is superimposed on the electric field roller 32 is obtained. It is trying to apply.

  In this case, the frequency of the AC component output from the AC bias power supply 40 is set so that the cycle is shorter than the time during which the liquid developer 10 passes through the nip between the electric field roller 32 and the developing roller 12. Specifically, since the difference between the background potential (that is, the charging potential) of the photosensitive member 1 and the development potential is 100 to 200 V, the bias voltage Vd of the electric field roller 32 is obtained by superimposing the AC component ± 50 V on the DC component 100 V. Since the time required for the liquid developer 10 to pass through the nip between the electric field roller 32 and the developing roller 12 is about 10 ms, the AC component frequency is set to about 100 to 200 Hz. .

  With this configuration, when the liquid developer 10 passes between the electric field roller 32 and the developing roller 12, the toner particles 10 a are attracted by the alternating electric field at the nip portion between the electric field roller 32 and the developing roller 12. It can be vibrated (shown with an arrow in the figure) to effectively weaken the cohesive force.

  As described above, when an electric field is applied to the liquid developer by the removal assisting means, the cohesive force can be effectively weakened by superimposing the AC component. Here, although an example using an electric field roller is described, the present invention is not limited to this.

Next, a sixth embodiment of the present invention will be described with reference to FIGS. FIG. 13 is an explanatory view of the cleaning means in the embodiment, and FIG. 14 is an explanatory view of the removal assisting means of the cleaning means.
In the present embodiment, a shearing unit as a removal assisting unit for applying a mechanical shearing force to the liquid developer 10 on the developing roller 12 to weaken the cohesive force is provided upstream of the cleaning blade 23 as a removal assisting unit. A rubber blade 61 is provided.

  The rubber blade 61 is arranged such that the surface side of the developing roller 12 is formed in a comb shape, and the comb teeth 61 a are in contact with the surface of the developing roller 12. In this case, the contact pressure of the rubber blade 61 against the surface of the developing roller 12 is set to a pressure that does not damage the surface of the developing roller 12. Further, in order to weaken the cohesive force between the toner particles of the liquid developer 10, it is more effective to increase the number of times the shearing force is applied. Therefore, the plurality of rubber blades 61 are shifted little by little at predetermined intervals. It is preferable to arrange.

  With this configuration, as shown in FIG. 13, toner particles aggregated in the liquid developer 10 remaining on the surface of the developing roller 12 (hereinafter omitted) are interposed between the comb teeth 61 a of the rubber blade 61. When passing, it receives a mechanical shearing force to change from a compressed state to a dispersed state, and the cohesive force between toner particles is weakened. Therefore, the liquid developer 10 in which such toner particles are dispersed can be removed by the cleaning blade 23 without the toner particles 10a clogging the tip.

  As described above, by using a shearing unit that applies a mechanical shearing force to the liquid developer on the developer carrying member to weaken the cohesive force as a removal assisting unit for weakening the cohesive force of the toner particles, the configuration can be simplified. The agglomerated toner particles can be easily dispersed to weaken the agglomeration force.

Next, a seventh embodiment of the present invention will be described with reference to FIG. In addition, FIG. 15 is explanatory drawing of the cleaning means in the same embodiment.
In this embodiment, a brush 62 is provided as a shearing means that is a removal assisting means, and the tip of the brush 62 is disposed in contact with the surface of the developing roller 12. As the brush 62, a metal (SUS or the like) fiber of about several tens to several tens of micrometers, or a bundle of acrylic fiber or nylon fiber can be used. However, in the case of a brush made of a metal fiber, the material itself has a high rigidity, and the surface of the developing roller 12 may be damaged unless the alignment is made sufficiently thin. It is preferable to use a material.

  Since the toner particles 10 a ′ aggregated in the liquid developer 10 remaining on the surface of the developing roller 12 pass between the fibers of the brush 62, the toner particles 10 a ′ are subjected to a mechanical shearing force from the compressed state. As a result, the cohesive force between the toner particles 10a is weakened.

  Thus, by using a brush as the shearing means, a shear force can be applied many times to the liquid developer remaining on the surface of the developing roller, and the cohesive force can be effectively reduced.

Next, an eighth embodiment of the present invention will be described with reference to FIG. In addition, FIG. 16 is explanatory drawing of the cleaning means in the same embodiment.
In the present embodiment, as a shearing unit that is a removal assisting unit, a roller 63 having a circumferential surface that is relatively movable with respect to the surface of the developing roller 12 is provided. The roller 63 is rotated so that a portion facing the surface of the developing roller 12 is opposite to the moving direction of the surface of the developing roller 12, and a speed difference is provided between the roller 63 and the developing roller 12. Yes.

  The roller 63 may have a smooth surface. For example, a stronger shearing force can be applied by forming a fine groove in a spiral shape on the surface. Or it can also be set as the cylindrical brush roller which planted the brush of the brush which was demonstrated in 7th Embodiment mentioned above on the surface of the cylindrical member.

  With this configuration, toner particles aggregated in the liquid developer 10 remaining on the surface of the developing roller 12 are subjected to mechanical shearing force when passing through the nip portion between the roller 63 and the developing roller 12. From the compressed state to the dispersed state, the cohesive force between the toner particles is weakened.

  Thus, by using a roller as the shearing means, it is possible to weaken the cohesive force by giving a mechanical shearing force to the liquid developer remaining on the surface of the developing roller with a simple configuration.

Next, a ninth embodiment of the present invention will be described with reference to FIG. FIG. 17 is an explanatory diagram of the cleaning means according to the embodiment.
In the present embodiment, a foam roller 66 in which a porous body (foam) layer 65 is formed on the peripheral surface of the cored bar 64 is provided as a shearing means that is a removal assisting means. For example, a sponge or the like can be used as the porous body layer 65. In order to prevent the liquid developer 10 from penetrating into the porous body layer 65, an open cell body (foamed foam) in which internal bubbles are continuous is used. It is preferable that it is a closed cell body (foam) in which the internal bubbles are independent rather than the body).

  With this configuration, when the toner particles aggregated in the liquid developer 10 remaining on the surface of the developing roller 12 pass through the nip portion between the porous body layer 65 of the foam roller 66 and the developing roller 12, the machine When subjected to a shearing force, the compressed state is changed to the dispersed state, and the cohesive force between the toner particles is weakened. At this time, since the peripheral surface of the foam roller 66 is composed of the porous body 65, it is possible to reduce the occurrence of scratches due to sliding contact with the surface of the developing roller 12.

  In this way, by using a roller whose peripheral surface is formed of a porous material containing bubbles inside as a shearing means, a liquid that remains on the surface of the developing roller with a simple configuration without damaging the surface of the developer carrying member. A cohesive force can be weakened by applying a mechanical shearing force to the developer.

Next, a tenth embodiment of the present invention will be described with reference to FIG. In addition, the figure is explanatory drawing of the rocking | fluctuation mechanism of the shearing means in the embodiment.
In the present embodiment, a swing mechanism 71 is provided for swinging the brush 62 that is the shearing means in the seventh embodiment in the axial direction of the developing roller 12. The swing mechanism 71 includes a cam plate 72 that rotates in a direction indicated by an arrow with a rotation shaft 72 a as a fulcrum by a drive motor (not shown), a support shaft 73 that stands on the cam plate 72, and a support shaft that stands on the brush 62. 74 are provided with link members 75 that are rotatably supported at both ends.

  Since it comprised in this way, the brush 62 is rock | fluctuated in the arrow direction (axial direction of the developing roller 12) via the link member 75 when the cam board 72 rotates in the arrow direction. As a result, the brush 62 can effectively apply a shearing force to weaken the cohesive force, and the contact position between the brush 62 and the developing roller can be changed to greatly reduce the occurrence of scratches on the surface of the developing roller. can do.

Next, an eleventh embodiment of the present invention will be described with reference to FIG. In addition, the figure is explanatory drawing of the rocking | fluctuation mechanism of the shearing means in the embodiment.
In the present embodiment, a swing mechanism 81 is provided for swinging the foam roller 66 which is the shearing means in the ninth embodiment in the axial direction of the developing roller 12. The swing mechanism 81 includes a cam groove 82 formed on the outer peripheral surface of one end portion of the foam roller 66, and a cam follower 85 that is provided at a distal end portion of an arm 84 fixed to the fixing portion 83 and engages with the cam groove 82. I have.

  With this configuration, when the foam roller 66 rotates in the direction indicated by the arrow, the foam roller 66 engages with the cam groove 82 in the direction indicated by the arrow (the axial direction of the developing roller 12). Swing. As a result, the foam roller 66 can effectively apply a shearing force to weaken the cohesive force, and the contact position between the foam roller 66 and the developing roller changes, so that the surface of the developing roller is greatly damaged. Can be reduced.

Next, a twelfth embodiment of the present invention will be described with reference to FIG. In addition, the figure is explanatory drawing of the rocking | fluctuation mechanism of the shearing means in the embodiment.
In the present embodiment, a swing mechanism 91 is provided for swinging the foam roller 66 which is the shearing means in the ninth embodiment in the axial direction of the developing roller 12. The swing mechanism 91 includes a cam surface 92 formed on one end surface of the foam roller 66, and a cam follower 95 provided at the distal end portion of an arm 94 fixed to the fixing portion 93 and abutting on the cam surface 92. . On the other hand, the foam roller 66 is urged to the side where the cam surface 92 on one end surface is pressed against the cam follower 95 by a compression spring 97 interposed between the other end surface and the fixing portion 96.

  Since the foam roller 66 rotates in the direction indicated by the arrow, since the cam follower 95 is in contact with the cam surface 92 when the foam roller 66 rotates in the direction of the arrow, the pressing force by the cam follower 95 and the urging force of the compression spring 97 Swings in the direction indicated by the arrow (the axial direction of the developing roller 12). As a result, the foam roller 66 can effectively apply a shearing force to weaken the cohesive force, and the contact position between the foam roller 66 and the developing roller changes, so that the surface of the developing roller is greatly damaged. Can be reduced.

  The shearing means provided with the swing mechanism as described above is not limited to that used in the above embodiment, but can be applied to the shearing means of the other embodiments described above.

Next, a thirteenth embodiment of the present invention will be described with reference to FIG. In addition, FIG. 21 is explanatory drawing of the removal assistance means based on the embodiment.
In this embodiment, the foam roller 100 as a shearing unit is formed by forming a foam layer 102 made of a porous material in which carbon or the like is dispersed on a cored bar member 101, and the foam roller 100 is biased as described above. By applying a bias voltage Vd on which an AC component is superimposed by the power supply 31 and the AC bias power supply 40, a mechanical shearing force is applied to the liquid developer and an electric field is applied to weaken the cohesive force. .

  With this configuration, when the toner particles 10a ′ aggregated in the liquid developer 10 remaining on the surface of the developing roller 12 pass through the nip portion between the foam roller 102 and the foam layer 102, mechanically. In addition to receiving the shearing force and receiving the electric field, the foam roller 100 is attracted to the foam roller 100 side, so that the compressed state is more surely changed to the dispersed state, and the cohesive force between the toner particles 10a is weakened.

  Here, the example in which the shearing means is a foam roller has been described, but even when a brush is used, an electric field can be applied by adjusting a resistance value by dispersing a metal filler or the like in a fiber material. become.

  As described above, by using the electric field and the mechanical shearing force in combination, the cohesive force between the toner particles can be effectively weakened, and the cleaning efficiency by the removal member thereafter can be improved. Thus, for example, even when a rubber blade is used as a removing member, the blade edge portion is not clogged with agglomerated toner, and the occurrence of scratches on the surface of the developing roller can be prevented. Can be improved.

Next, a fourteenth embodiment of the present invention is described with reference to FIG. FIG. 22 is an explanatory diagram of the developing device in the embodiment.
In the present embodiment, the carrier liquid 10b recovered from the surface of the photosensitive member 1 by the sweep roller 13A and scraped and recovered from the surface of the sweep roller 13A by the cleaning blade 16A is passed through the carrier supply path 18 formed by extending from the housing 17. The nip portion 110 between the electric field roller 32 and the developing roller 12, that is, the region where the cohesive force of the liquid developer 10 is weakened is supplied.

  With this configuration, when the electric field roller 32 applies an electric field to the liquid developer 10 remaining on the surface of the developing roller 12 to weaken the cohesive force, the recovered carrier liquid 10b is replenished and supplied to the liquid developer 10. As a result, the cohesive force of the liquid developer 10 can be reduced more efficiently. Here, an example in which an electric field roller is used as the removal assisting unit has been described. However, other removal assisting units in the above-described embodiments may be used.

  That is, the liquid developer 10 remaining on the developing roller 12 is transferred from the carrier liquid 10b of the liquid developer 10 onto the photoconductor 1 on the background portion of the photoconductor 1, so that the toner in the liquid developer 10 The concentration of the particles is increased, which contributes to increasing the cohesive force of the toner particles.

  Therefore, by supplying the carrier liquid 10b constituting the liquid developer 10 to the region where the cohesive force of the liquid developer 10 is weakened, the concentration of the liquid developer 10 is lowered, so the cohesive force between the toner particles is reduced. In order to weaken, when an electric field is applied, the effect of weakening the cohesive force is greater than when the carrier liquid 10b is not replenished and supplied.

  Here, as the carrier liquid 10b for supplying to the area where the cohesive force of the liquid developer 10 is weakened, an appropriate amount can be supplied from the new carrier liquid 10b. By reusing the excess carrier liquid 10b collected by the sweep roller 13A, which is a means for removing the excess of the carrier liquid 10b adhering to the carrier (photoconductor) 1, the carrier liquid 10b New replenishment amount can be reduced.

  Further, since the liquid developer 10 on the developing roller 12 is separated into the photosensitive member 1 and the developing roller 12 by development, the excess carrier liquid 10b collected on the photosensitive member 1 by the sweep roller 13A is developed. The relationship is such that the carrier in the liquid developer remaining on the roller 12 is compensated.

  In this way, after development, a surplus of the carrier liquid adhering to the latent image carrier (photoconductor) is removed and recovered, and then supplied to a region where the cohesive force of the liquid developer is weakened to newly supply. Therefore, it is possible to omit a configuration for storing and supplying carriers for the purpose, and thus the size and cost of the apparatus can be reduced.

Next, a fifteenth embodiment of the present invention is described with reference to FIG. FIG. 23 is an explanatory diagram of the developing device in the embodiment.
In this embodiment, the liquid developer 10 is applied between the application roller 21 and the development roller 12 by the application roller 21 on the peripheral surface, and the applied liquid developer 10 is transferred and applied to the peripheral surface of the development roller 12. An intermediate roller 120 as an application member is interposed, and a cleaning blade 121 is brought into contact with the peripheral surface of the intermediate roller 120 from a direction opposite to the rotation direction.

  The intermediate roller 120 rotates in the same direction (arrow direction) as the developing roller 12 so that the contact surface with the developing roller 12 moves in the opposite direction, so that the liquid development after development remaining on the surface of the developing roller 12 is performed. The agent 10 also serves as a removing means for applying a shearing force to remove the liquid developer 10 remaining on the surface of the developing roller 12.

  Then, the electric field roller 32 described above, which is a removal assisting means for weakening the cohesive force of the toner particles of the liquid developer 10 remaining on the surface of the developing roller 12 on the upstream side of the intermediate roller 120 in the rotation direction of the developing roller 12, is provided. Provided. Here, an example in which an electric field roller is used as the removal assisting unit has been described. However, other removal assisting units in the above-described embodiments may be used.

  Further, a pre-development charging charger 122, which is a pre-development electric field applying means such as a corona charger for applying an electric field to the liquid developer 10 on the developing roller 12 and compressing it before the development, is provided. Further, as in the fourteenth embodiment, the carrier liquid 10b collected from the surface of the photoreceptor 1 by the sweep roller 13A and scraped off from the surface of the sweep roller 13A by the cleaning blade 16A is extended from the housing 17 and formed. Through the carrier supply path 18, the nip portion 110 between the electric field roller 32 and the developing roller 12, that is, the region where the cohesive force of the liquid developer 10 is weakened is supplied. A doctor roller 123 is used as means for measuring the liquid developer 10 on the application roller 21.

  With this configuration, even when the intermediate roller 120 is used as the removing unit, the liquid developer 10 remaining on the developing roller 12 can be reliably removed.

  That is, when the intermediate roller 120 is used as the removing means, damage to the surface of the developing roller 12 by the intermediate roller 120 can be reduced as compared with the case of using the blade, but both rollers 12 and 120 are in contact with each other with a nip. Therefore, when the contact pressure becomes weak and the toner particles of the liquid developer 10 remaining on the developing roller 12 are agglomerated, the removal performance deteriorates.

  In addition, an electric field is applied to the pre-development liquid developer 10 on the developing roller 12 by the pre-development charging charger 122, and the development is performed after compressing the liquid developer 10, so that the toner particles on the background portion are transferred. Since adhesion is prevented, the aggregation of toner particles of the liquid developer 10 remaining on the developing roller 12 after development is several times stronger than in the case where compression before development is not performed. It becomes difficult to remove the liquid developer 10 on the developing roller 12 only.

  Therefore, by providing a removal assisting means that weakens the cohesive force of the liquid developer 10 by applying an electric field to the upstream side of the intermediate roller 120, even when the intermediate roller 120 is used as the removing means, the electric field applying means 122 further Even when the liquid developer 10 is compressed by applying an electric field to the liquid developer 10 before development, the liquid developer 10 is removed by the intermediate roller 120 as a removing means after the cohesive force of the liquid developer 10 on the developing roller 12 is weakened. Therefore, the liquid developer 10 can be reliably removed.

  In addition, as in the fourteenth embodiment, by supplying the carrier liquid to a region where the cohesive force of the liquid developer is weakened, the liquid developer 10 remaining on the developing roller 12 is more reliably removed by the intermediate roller 120. Can be removed.

  As described above, even when the intermediate application member is used as the removing means, the removal supporting means for weakening the cohesive force of the liquid developer is provided on the upstream side in the rotation direction of the developer carrying body, thereby remaining on the developer carrying body. The liquid developer to be removed can be surely removed, the improvement of the life of the developer carrier by the intermediate coating member and the removal performance of the remaining liquid developer can be compatible, and the life of the developer carrier can be further increased. Can be improved.

  Similarly, even when development is performed after applying an electric field to the liquid developer on the developer carrier before being compressed, the liquid developer remaining on the developer carrier can be reliably removed. In addition, the improvement in image quality and the performance of removing the remaining liquid developer can be compatible, and the life of the developer carrier can be improved.

1 is a schematic configuration diagram illustrating an example of an image forming apparatus including a developing device according to a first embodiment of the present invention. FIG. 2 is an enlarged explanatory view of a developing device portion of the image forming apparatus. It is front explanatory drawing of the coating roller used for the developing device. It is an expansion perspective explanatory view showing the example from which the shape of the engraving groove on the surface of the application roller of the developing device differs. FIG. 6 is an explanatory diagram for explaining a liquid developer in a non-image portion of a developing nip portion in the developing device. FIG. 7 is an explanatory diagram for explaining the occurrence of defective removal due to aggregation of toner particles of a liquid developer in a developing device. FIG. 6 is an explanatory diagram for explaining an action of removing a residual liquid developer in the developing device. It is explanatory drawing with which it uses for description of the cleaning means in 2nd Embodiment of this invention. It is explanatory drawing with which it uses for description of the removal assistance means in 3rd Embodiment of this invention. It is explanatory drawing with which it uses for description of the removal assistance means in 4th Embodiment of this invention. FIG. 6 is a perspective explanatory view for explaining a driving mechanism of the electric field roller in the same embodiment. It is explanatory drawing with which it uses for description of the removal assistance means in 5th Embodiment of this invention. It is explanatory drawing with which it uses for description of the cleaning means in 6th Embodiment of this invention. It is explanatory drawing similarly used for description of a removal assistance means. It is explanatory drawing with which it uses for description of the cleaning means in 7th Embodiment of this invention. It is explanatory drawing with which it uses for description of the cleaning means in 8th Embodiment of this invention. It is explanatory drawing with which it uses for description of the cleaning means in 9th Embodiment of this invention. It is explanatory drawing with which it uses for description of the rocking | fluctuation mechanism of the removal assistance means in 10th Embodiment of this invention. It is explanatory drawing with which it uses for description of the rocking | fluctuation mechanism of the removal assistance means in 11th Embodiment of this invention. It is explanatory drawing with which it uses for description of the rocking | fluctuation mechanism of the removal assistance means in 12th Embodiment of this invention. It is explanatory drawing with which it uses for description of the cleaning means in 13th Embodiment of this invention. It is an expansion explanatory view of the development device concerning a 14th embodiment of the present invention. It is an expansion explanatory view of the developing device concerning a 15th embodiment of the present invention.

Explanation of symbols

1 ... Photoconductor (image carrier)
2A, 2B ... charger 3 ... optical writing device 4 ... developing device 5 ... transfer device 6 ... neutralizing lamp 7 ... cleaning device 11 ... liquid developer container 12 ... developing roller (developer carrier)
13A, 13B ... Sweep roller 21 ... Application roller 22 ... Doctor blade 23 ... Cleaning blade (removing means)
24. Removal assisting means

Claims (16)

  A developer carrier for carrying a liquid developer and developing a latent image formed on the image carrier, and a removing means for removing the liquid developer remaining on the developer carrier after development And a removal assisting means for weakening the cohesive force of the liquid developer on the developer carrier on the upstream side of the removing means.   The developing device according to claim 1, wherein the removal assisting unit is an electric field forming unit that applies an electric field to the liquid developer on the developer carrying member to weaken a cohesive force.   3. The developing device according to claim 2, wherein the electric field forming means is an electrode member disposed to face the surface of the developer carrying member.   The developing device according to claim 2, wherein the electric field forming means is a roller member.   5. The developing apparatus according to claim 2, wherein the electric field forming unit forms an electric field including an alternating current component.   2. The developing device according to claim 1, wherein the removal assisting unit is a shearing unit that applies a mechanical shearing force to the liquid developer on the developer carrier and weakens a cohesive force. apparatus.   7. The developing device according to claim 6, wherein the shearing means is a brush arranged in contact with the surface of the developer carrying member.   7. The developing device according to claim 6, wherein the shearing means is a roller whose peripheral surface is arranged to be relatively movable with respect to the surface of the developer carrying member.   The developing device according to claim 8, wherein the roller is formed of a porous material containing bubbles therein.   10. The developing device according to claim 7, wherein the shearing unit is disposed so as to be swingable in an axial direction of the developer carrier.   The developing device according to claim 1, wherein the removal assisting unit is a unit that applies an electric field to the liquid developer on the developer carrying member and weakens a cohesive force by applying a mechanical shearing force. A developing device for a liquid developer.   12. The developing device according to claim 1, further comprising means for supplying the carrier liquid constituting the liquid developer to an area in which the cohesive force of the liquid developer is weakened by the removal assisting means. A developing device.   13. The developing device according to claim 12, wherein after development, excess carrier liquid adhering to the image bearing member is removed and recovered, and supplied to an area where the cohesive force of the liquid developer is weakened. Developing device.   14. The developing device according to claim 1, wherein the removing unit also serves as a member for applying a liquid developer to the developer carrying member.   15. The developing device according to claim 1, further comprising means for applying an electric field to the liquid developer applied to the developer carrier before development. apparatus. An image forming apparatus comprising a developing device for developing an electrostatic latent image formed on an image carrier using a liquid developer, comprising the developing device according to claim 1. An image forming apparatus.

Images