JP2007121395A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus using liquid developer and achieving efficient cleaning for a developing roller or the like having an elastic surface. <P>SOLUTION: An elastic roller 71 such as the developing roller, in the image forming apparatus, functions to develop a latent image formed on an image carrier. In an image forming process, toner evenly dispersed on carrier is flocculated on the surface side of the elastic roller 71 by compaction. The image forming apparatus is provided with a cleaning blade 72 in order to remove the flocculated toner. The surface of the elastic roller 71 is formed of an elastic surface layer, and the elastic surface layer is changed from a low-density foaming part to a high-density non-foaming part that is made of the same material as the low-density foaming part from the inside diameter to the outside diameter of the roller and has hardness of ASKER C 30 to 50 used for the elastic surface layer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  In the present invention, a latent image formed on an image carrier is developed by a developing device for liquid developer and transferred from the image carrier to an intermediate transfer member at a transfer position of the primary transfer unit. The present invention relates to an image forming apparatus using a liquid developer that is transferred to a recording medium at a transfer position.

  Various wet image forming apparatuses that develop a latent image using a high-viscosity liquid developer in which a toner composed of a solid component is dispersed in a liquid solvent and visualize the electrostatic latent image have been proposed. The developer used in this wet image forming apparatus is obtained by suspending solids (toner particles) in an electrically insulating organic solvent (carrier liquid) made of silicon oil, mineral oil, edible oil, and the like. The toner particles have a very fine particle diameter of about 1 μm. By using such fine toner particles, the wet image forming apparatus can achieve higher image quality than a dry image forming apparatus using powder toner particles having a particle diameter of about 7 μm.

The carrier liquid constituting the developer has a function of making the toner particles charged and further uniformly dispersed in addition to preventing the scattering of toner particles having a particle diameter of about 1 μm. It also has a role to make it easy to move by electric field action. As described above, the carrier liquid is a component necessary for toner storage, toner conveyance, development, and transfer processes, but also adheres to non-image areas, and excessive carrier liquid after development causes transfer disturbance and the like. For this reason, the carrier liquid is usually removed (squeezed) from the developer on the photosensitive member and the intermediate transfer member (see, for example, Patent Document 1). Further, on a roller such as a developing roller, toner particles uniformly dispersed in a carrier liquid are biased to move to the roller surface side to be aggregated. In the wet image forming apparatus, when an intermediate transfer belt or a secondary transfer belt is used, the liquid developer (carrier liquid and solid content) adhering to the belt surface is removed by a cleaning blade. (For example, see Patent Document 3).
JP 2002-296918 A JP 2000-56576 A JP 2002-189354 A

  By the way, as a cleaning structure in an image forming apparatus using the liquid developer as described above, a structure in which a cleaning blade formed of urethane rubber is slidably contacted on a member to be cleaned is an image carrier having a hard surface. However, it is difficult to achieve efficient cleaning for a developing roller having an elastic surface. In particular, a developing roller that cleans the compacted developer by applying an electric field from a compaction roller or a corona discharger to a developing roller carrying toner uniformly dispersed in a carrier to move the toner to the developing roller side to cause aggregation. Cleaning is very difficult. Cleaning not only the developing roller but also the rollers having elastic surfaces disposed in various places of the image forming apparatus has a problem that cleaning conditions are severe and it is difficult to perform efficient cleaning.

  The present invention is to solve the above-described problems. A latent image formed on an image carrier is developed by a developing roller and transferred from the image carrier to an intermediate transfer member at a transfer position of a primary transfer portion. In an image forming apparatus using a liquid developer that is transferred from a transfer body to a recording medium at a transfer position of a secondary transfer unit, the developing roller having an elastic surface layer is used, and the developing roller cleaning blade is brought into contact with the developing roller. The developing roller is provided with a compaction mechanism, and the elastic surface layer moves from a low density foamed portion to a high density non-foamed portion with the same material as the foamed portion as it goes from the inner diameter to the outer diameter of the roller. A hardness of ASKER C of 30 to 50 degrees is used.

  The invention according to claim 2 is the image forming apparatus according to claim 1, wherein the material is polyurethane foam, polystyrene foam, polyethylene foam, elastomer foam, or rubber foam.

  The invention according to claim 3 is the image forming apparatus according to claim 1 or 2, wherein the developing roller cleaning blade uses polyurethane rubber having a hardness of JIS A 60 to 100 degrees.

  According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, a fluorine-based resin is fixed to the developing roller contact portion of the developing roller cleaning blade. It is characterized by.

  According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, the developing roller at the pressing sliding contact point where the protruding end of the developing roller cleaning blade presses and contacts the developing roller. When the angle formed by the contact surface of the developing roller cleaning blade with respect to a vertical line perpendicular to the generating line is θ, θ is 6 ° to 30 °.

  According to the present invention, even after the toner particles are pressed against the intermediate transfer member by a bias having a polarity opposite to the toner charging polarity of the liquid developer to be in a compaction state, the elastic layer of the developing roller is formed with an uneven portion due to elastic deformation. In addition to reducing the frictional force with which the cleaning blade is pressed and slidably contacted, the adhesion force with which the toner particles are adhered and supported on the surface of the developing roller is also reduced, so that a good cleaning function can be exhibited.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing main components constituting the image forming apparatus according to the embodiment of the present invention. Development units 30Y, 30M, 30C, and 30K are arranged at the lower part of the image forming apparatus, and the intermediate transfer member 40 and the secondary transfer unit 60 Arranged at the top of the image forming apparatus.

  The image forming unit includes image carriers 10Y, 10M, 10C, and 10K, charging rollers 11Y, 11M, 11C, and 11K, and exposure units 12Y, 12M, 12C, and 12K (not shown). The exposure units 12Y, 12M, 12C, and 12K have an optical system such as a semiconductor laser, a polygon mirror, and an F-θ lens. The image bearing members 10Y, 10M, 10C, and 10K are provided by charging rollers 11Y, 11M, 11C, and 11K. Are uniformly charged and irradiated with a modulated laser beam based on the input image signal by the exposure units 12Y, 12M, 12C, and 12K, and charged image carriers 10Y, 10M, 10C, and 10K. An electrostatic latent image is formed thereon.

  The developing units 30Y, 30M, 30C, and 30K generally include liquid developers of respective colors including the developing rollers 20Y, 20M, 20C, and 20K, yellow (Y), magenta (M), cyan (C), and black (K). Developer containers (reservoirs) 31Y, 31M, 31C, 31K to be stored, and developer supply rollers for supplying liquid developers of these colors from the developer containers 31Y, 31M, 31C, 31K to the developing rollers 20Y, 20M, 20C, 20K 32Y, 32M, 32C, 32K and the like, and the electrostatic latent images formed on the image carriers 10Y, 10M, 10C, and 10K are developed with liquid developers of respective colors.

  The intermediate transfer member 40 is an endless belt, and is stretched between the driving roller 41 and the tension roller 42, and is contacted with the image carriers 10Y, 10M, 10C, and 10K by the primary transfer portions 50Y, 50M, 50C, and 50K. It is rotationally driven by the driving roller 41 while in contact. The primary transfer units 50Y, 50M, 50C, and 50K are arranged such that the primary transfer rollers 51Y, 51M, 51C, and 51K are opposed to each other with the image transfer bodies 10Y, 10M, 10C, and 10K sandwiched between the intermediate transfer body 40 and the image transfer bodies 10Y, Using the contact position with 10M, 10C, and 10K as the transfer position, the developed toner images of the respective colors on the image carriers 10Y, 10M, 10C, and 10K are sequentially superimposed and transferred onto the intermediate transfer body 40 to obtain a full-color toner. Form an image.

  In the secondary transfer unit 60, a secondary transfer roller 61 is disposed opposite to the belt drive roller 41 with the intermediate transfer member 40 interposed therebetween, and a cleaning device including a secondary transfer roller cleaning blade 62 and a developer recovery unit 63 is disposed. The Then, at the transfer position where the secondary transfer roller 61 is disposed, a single color toner image or a full color toner image formed on the intermediate transfer body 40 is conveyed on the sheet material conveyance path L such as paper, film, cloth, etc. Transfer to recording medium.

  Further, a fixing unit (not shown) is disposed in front of the path sheet material conveyance path L, and a single color toner image or a full color toner image transferred onto a recording medium such as paper is fused to the recording medium such as paper. And fix.

  An intermediate transfer body compaction roller 43 is disposed opposite to the tension roller 42 that stretches the secondary transfer unit 60 together with the belt drive roller 41 so as to contact the intermediate transfer body 40 along its outer periphery. A cleaning device including an intermediate transfer member cleaning blade 46 and a developer recovery unit 47 is disposed downstream of the intermediate transfer member compaction roller 43 in the moving direction of the intermediate transfer member 40. An intermediate transfer body compaction roller cleaning blade 44 and a developer recovery unit 45 are disposed opposite to the outer periphery of the intermediate transfer body compaction roller 43. The intermediate transfer body compaction roller 43 receives residual toner on the intermediate transfer body 40. A bias having a polarity to be pressed against the intermediate transfer member 40 is applied.

  Next, the image forming unit and the developing unit will be described. FIG. 2 is a cross-sectional view showing main components of the image forming unit and the developing unit. 3 is a diagram for explaining compaction by the compaction roller 22Y, FIG. 4 is a diagram for explaining development by the developing roller 20Y, FIG. 5 is a diagram for explaining the squeeze action by the image carrier squeeze roller 13Y, and FIG. 6 is an intermediate transfer member squeeze. It is a figure explaining the squeeze effect | action by the apparatus 52Y. Since the configurations of the image forming unit and the developing unit for each color are the same, the following description will be made based on the yellow (Y) image forming unit and the developing unit.

  The image forming unit includes a cleaning device including a latent image eraser 16Y, an image carrier cleaning blade 17Y, and a developer recovery unit 18Y along the rotation direction of the outer periphery of the image carrier 10Y, a charging roller 11Y, an exposure unit 12Y, and a development unit. A cleaning device including a developing roller 20Y of 30Y, an image carrier squeeze roller 13Y, an image carrier squeeze roller cleaning blade 14Y, and a developer recovery unit 15Y, which are associated with the development roller 20Y, is provided. In the developing unit 30Y, a cleaning blade 21Y, a developer supply roller 32Y using an anilox roller, and a compaction roller 22Y are disposed on the outer periphery of the developing roller 20Y, and a liquid developer stirring roller 34Y is disposed in the liquid developer container 31Y. The developer supply roller 32Y is accommodated. A primary transfer roller 51Y of the primary transfer portion is disposed along the intermediate transfer body 40 at a position facing the image carrier 10Y, and an intermediate transfer body squeeze roller 53Y, a backup roller 54Y, and an intermediate transfer are disposed downstream in the moving direction. An intermediate transfer body squeeze device 52Y comprising a body squeeze roller cleaning blade 55Y and a developer recovery unit 56Y is disposed.

  The image carrier 10Y is a photosensitive drum made of a cylindrical member having a width wider than about 320 mm of the developing roller 20Y and a photosensitive layer formed on the outer peripheral surface. For example, the image carrier 10Y rotates in a clockwise direction as shown in FIG. To do. The photosensitive layer of the image carrier 10Y is composed of an organic image carrier or an amorphous silicon image carrier. The charging roller 11Y is disposed upstream of the nip portion between the image carrier 10Y and the developing roller 20Y in the rotation direction of the image carrier 10Y, and a bias having the same polarity as the toner charging polarity is applied from a power supply device (not shown) to The carrier 10Y is charged. The exposure unit 12Y irradiates laser light onto the image carrier 10Y charged by the charging roller 11Y on the downstream side in the rotation direction of the image carrier 10Y with respect to the charging roller 11Y, thereby forming a latent image on the image carrier 10Y. To do.

  The developing unit 30Y includes a compaction roller 22Y, a developer container 31Y that stores a liquid developer in which toner is dispersed in a carrier at a weight ratio of approximately 25%, a developing roller 20Y that carries the liquid developer, and a liquid developer. The developer supply roller 32Y, the regulating blade 33Y, the agitation roller 34Y, and the liquid developer carried on the development roller 20Y for maintaining the mixture in a uniform dispersed state and supplying it to the development roller 20Y are compacted so as to be in a compaction state. A developing roller cleaning blade 21Y for cleaning the roller 22Y and the developing roller 20Y is provided.

  The liquid developer accommodated in the developer container 31Y is a low concentration (about 1 to 2 wt%) and low viscosity with Isopar (trademark: exon) as a carrier, which is generally used, and is volatile at room temperature. It is not a volatile liquid developer having a property, but a non-volatile liquid developer having a high concentration and a high viscosity and having a non-volatile property at room temperature. That is, in the liquid developer in the present invention, a solid having an average particle diameter of 1 μm in which a colorant such as a pigment is dispersed in a thermoplastic resin is introduced into a liquid solvent such as an organic solvent, silicon oil, mineral oil, or edible oil. It is a liquid developer having a high viscosity (about 30 to 10,000 mPa · s) which is added together with a dispersant and has a toner solid content concentration of about 25%.

  The developer supply roller 32Y is a cylindrical member that rotates in a clockwise direction as shown in FIG. 2, for example, and has a fine and uniform spiral groove on the surface so that the developer can be easily carried on the surface. It is an anilox roller which formed the uneven surface by. The groove dimensions are such that the groove pitch is about 130 μm and the groove depth is about 30 μm. The developer supply roller 32Y supplies the liquid developer from the developer container 31Y to the developing roller 20Y. The stirring roller 34Y and the developer supply roller 32Y may be in sliding contact with each other, but may be arranged in a distant relationship.

  The regulating blade 33Y is composed of an elastic blade whose surface is covered with an elastic body, a rubber portion made of urethane rubber or the like that contacts the surface of the developer supply roller 32Y, and a metal plate or the like that supports the rubber portion. The Then, the film thickness and amount of the liquid developer carried and conveyed by the developer supply roller 32Y composed of an anilox roller are regulated and adjusted, and the amount of liquid developer supplied to the developing roller 20Y is adjusted. Note that the rotation direction of the developer supply roller 32Y may be the opposite direction instead of the arrow direction shown in FIG. 2, and the regulating blade 33Y at that time requires an arrangement corresponding to the rotation direction.

  The developing roller 20Y is a cylindrical member having a width of about 320 mm, and rotates counterclockwise around the rotation axis as shown in FIG. The developing roller 20Y is provided with an elastic layer made of polyurethane rubber, silicon rubber, NBR or the like on the outer periphery of an inner core made of metal such as iron. The developing roller cleaning blade 21Y is made of rubber or the like that comes into contact with the surface of the developing roller 20Y. The developing roller 20Y is arranged downstream of the developing nip portion where the developing roller 20Y comes into contact with the image carrier 10Y in the rotation direction of the developing roller 20Y. The liquid developer remaining on the developing roller 20Y is scraped off and removed.

  The compaction roller 22Y is a cylindrical member, and is in the form of an elastic roller configured to cover the elastic body 22-1Y as in the developing roller 20Y as shown in FIG. 3, and is conductive on the surface of the metal roller base material. For example, as shown in FIG. 2, the resin layer and the rubber layer are rotated in the clockwise direction opposite to the developing roller 20Y. The compaction roller 22Y has means for increasing the charging bias on the surface of the developing roller 20Y, and the developer conveyed by the developing roller 20Y slides into contact with the compaction roller 22Y to form a nip as shown in FIGS. An electric field is applied from the compaction roller 22Y side toward the developing roller 20Y at the compaction site. The electric field applying means for compaction may be corona discharge from a corona discharger instead of the roller shown in FIG.

  With this compaction roller 22Y, as shown in FIG. 3, the toner T uniformly dispersed in the carrier C is moved to the developing roller 20Y side to be aggregated to form a so-called compaction state T ′. A small amount of toner T ″ that has not been compacted is carried, rotated in the direction of the arrow in the figure, scraped off by the compaction roller cleaning blade 23Y, joined with the developer in the reservoir 31Y, and reused. The developer D carried and compacted by the roller 20Y is converted into a latent image on the image carrier 10Y by applying a desired electric field at the developing nip where the developing roller 20Y contacts the image carrier 10Y as shown in FIG. The remaining developer D is developed by the developing roller cleaning blade 21Y. Is reused merged with the developer in the removed reservoir 31Y scrapes off Te. The carrier and the toner to these joins are not mixed color state.

  The image carrier squeeze device is disposed on the downstream side of the developing device 20Y so as to face the image carrier 10Y and collects the excess developer of the toner image developed on the image carrier 10Y. As shown in FIG. 5, an image carrier squeeze roller 13Y comprising an elastic roller member that covers the surface with an elastic member 13-1Y and rotates in sliding contact with the image carrier 10Y, and press-slidably contacts the image carrier squeeze roller 13Y. And a cleaning blade 14Y for cleaning the surface, and as shown in FIG. 5, the excess carrier C and the originally unnecessary fog toner T ″ are collected from the developer D developed on the image carrier 10Y, The recovery capability of the surplus carrier C is based on the rotational direction of the image carrier squeeze roller 13Y and the peripheral speed of the surface of the image carrier 10Y. The desired recovery capability can be set by the relative peripheral speed difference of the surface of the body squeeze roller 13Y. When the image carrier 10Y is rotated in the counter direction, the recovery capability is increased, and the peripheral speed difference is reduced. Even if it is set to a large value, the recovery capability is enhanced, and further, this synergistic action is possible.

  In this embodiment, as an example, as shown in FIG. 5, the image carrier squeeze roller 13Y is rotated with the image carrier 10Y at substantially the same peripheral speed, and the weight ratio from the developer D developed on the image carrier 10Y is increased. The excess carrier C of about 5 to 10% is collected to reduce both rotational driving loads and suppress the disturbance effect on the visible toner image of the image carrier 10Y. Excess carrier C and unnecessary fog toner T ″ collected by the image carrier squeeze roller 13Y are collected and pooled from the image carrier squeeze roller 13Y to the developer collecting unit 15Y by the action of the cleaning blade 14Y. Since the collected excess carrier C and fog toner T ″ are collected from the dedicated isolated image carrier 10Y, no color mixing phenomenon occurs at all locations.

  In the primary transfer unit 50Y, the developer image developed on the image carrier 10Y is transferred to the intermediate transfer member 40 by the primary transfer roller 51Y. Here, the image carrier 10Y and the intermediate transfer member 40 are configured to move at a constant speed, reducing the driving load of rotation and movement, and suppressing the disturbance effect on the visible toner image of the image carrier 10Y. Yes. The primary transfer portion 50Y for the first color does not cause a color mixing phenomenon since it is the first primary transfer, but since the second and subsequent colors transfer different toner images onto the already transferred primary toner image portions and superimpose colors, the intermediate transfer body 40 is used. Due to the so-called reverse transfer phenomenon in which the toner moves from the image carrier 10 (M, C, K) to the image carrier 10 (M, C, K), the reverse transfer toner and the untransferred toner are mixed and are carried on the image carrier 10 (M, C, K) together with the surplus carrier. Moved from the image carrier by the action of the cleaning blade 17 (M, C, K) and pooled.

  The intermediate transfer member squeeze device 52Y is disposed on the downstream side of the primary transfer unit 50Y, and removes excess carrier liquid from the intermediate transfer member 40 to increase the toner particle ratio in the visible image. In the stage where the carrier amount of the developer (toner dispersed in the carrier) transferred to the intermediate transfer body 40 by the transfer unit 50Y is secondarily transferred to the above-described final-stage sheet material and proceeds to the fixing process (not shown), In order to exhibit a preferable secondary transfer function and fixing function, excess carrier is further removed from the intermediate transfer body 40 when the approximate toner weight ratio of the desired dispersion state of the liquid developer does not reach about 40% to 60%. It is provided as a means. Similar to the image carrier squeeze device 52, the intermediate transfer member squeeze device 52Y has an intermediate transfer member squeeze roller 53Y composed of an elastic roller member that covers the surface with an elastic member and rotates in sliding contact with the image carrier 40, and the image carrier 40. 6 includes a backup roller 54Y disposed opposite to the intermediate transfer member squeeze roller 53Y, a cleaning blade 55Y that presses and slides against the intermediate transfer member squeeze roller 53Y to clean the surface, and a developer recovery unit 56Y, as shown in FIG. As described above, it has a function of recovering excess carrier C and originally unnecessary fog toner T ″ from the developer D primarily transferred to the intermediate transfer body 40. The developer recovery section 56Y is provided with magenta magenta disposed downstream thereof. Also serves as a recovery mechanism for the carrier liquid recovered by the image carrier squeeze roller cleaning blade 14M. There.

  The surplus carrier collecting ability can be set to a desired collecting ability by the relative circumferential speed difference of the surface of the intermediate transfer member squeeze roller 53Y with respect to the rotation direction of the intermediate transfer member squeeze roller 53Y and the moving speed of the intermediate transfer member 40. When the intermediate transfer member 40 is rotated in the counter direction, the recovery capability is increased, and even when the peripheral speed difference is set to be large, the recovery capability is increased, and this synergistic action is also possible. In this embodiment, as an example, the intermediate transfer member squeeze roller 53Y rotates with the intermediate transfer member 40 at substantially the same peripheral speed, and a weight ratio of about 5 to 10% from the developer primarily transferred to the intermediate transfer member 40 is obtained. The excess carrier and fog toner are collected to reduce both rotational driving loads and to suppress the disturbance effect on the toner image of the intermediate transfer member 40.

  The first color intermediate squeeze squeeze part is the first intermediate squeeze squeeze, so no color mixing phenomenon occurs. However, after the second color, a different toner image is transferred to the already transferred primary toner image part and overlaid. Therefore, when the toner is transferred from the intermediate transfer body 40 to the intermediate transfer body squeeze roller 53Y, the toner is mixed in color and carried and moved by the intermediate transfer body squeeze roller 53Y together with the surplus carrier. Collected from 53Y and pooled. Further, when the squeeze ability by the image carrier 40 at the primary transfer portion upstream of the intermediate transfer member squeeze process and the squeeze ability of the image carrier squeeze roller 53Y are performed with sufficient ability, not all primary transfer processes are necessarily performed. There is no need to provide an intermediate transfer member squeeze device on the downstream side.

  Next, the operation of the image forming apparatus of the present invention will be described. Subsequently, the image forming unit and the developing unit will be described by taking the yellow image forming unit and the developing unit 30Y among the four image forming units and the developing unit as an example.

  In the developer container 31Y, the toner particles in the liquid developer have a positive charge. The liquid developer is stirred by the stirring roller 34Y, and the developer supply roller 32Y rotates, whereby the developer container 31Y. Pumped from. The liquid development image forming apparatus using the developer in which the toner is dispersed in the carrier according to the present embodiment uses a developer in which 25% of the toner is dispersed in 75% of the carrier in an approximate weight ratio. In the stage of image formation through the process, secondary transfer to the final stage sheet material and proceeding to the fixing process (not shown), the liquid developer has an approximate toner weight in order to exhibit a preferable secondary transfer function and fixing function. It is desirable that the dispersion state is about 40% to 60% in terms of the ratio. The developer initially stored in the developer container 31Y is in a state of being dispersed in the carrier at approximately a toner weight ratio of about 25%. However, in the case of developing on the image carrier 10Y, the toner is used when the image duty is high. In the case of development with a high consumption ratio of toner and a low image duty, the consumption ratio of toner is reduced. That is, the toner weight ratio of the developer stored in the developer container 31Y changes with the development of the image carrier 10Y, and this change is constantly monitored and the toner weight ratio is about 25%. It is necessary to maintain and control in a distributed state.

  Therefore, in this embodiment, a transmission type photo sensor for detecting the dispersion weight ratio of the toner (not shown), torque detecting means for detecting the stirring torque for stirring the developer, and the developer liquid level in the developer container 31Y are detected. A reflective photosensor or the like is provided in the developer container 31Y, and when the toner dispersion weight ratio decreases for a predetermined developer amount, the developer dispersed at a high concentration of about 35 to 55% is used. When a predetermined amount of toner is replenished from the developer cartridge and the toner dispersion weight ratio increases, a predetermined amount of carrier is replenished from the carrier cartridge to control the toner to approximately 25% of the toner weight ratio, and inside the developer container 31Y. And uniformly dispersed.

  The regulating blade 33Y is in contact with the surface of the developer supply roller 32Y and scrapes off other excess liquid developer while leaving the liquid developer in the uneven grooves of the anilox pattern formed on the surface of the developer supply roller 32Y. Thus, the amount of liquid developer supplied to the developing roller 20Y is regulated. By such regulation, the film thickness of the liquid developer applied to the developing roller 20Y is quantified so as to be about 6 μm. The liquid developer scraped off by the regulating blade 33Y falls back to the developer container 31Y due to gravity, and the liquid developer that has not been scraped off by the regulating blade 33Y forms an uneven groove on the surface of the developer supply roller 32Y. It is accommodated inside and is applied to the surface of the developing roller 20Y by being pressed against the developing roller 20Y.

  The developing roller 20Y coated with the liquid developer by the developer supply roller 32Y comes into contact with the compaction roller 22Y downstream of the nip portion with the developer supply roller 32Y. A bias of about +400 V is applied to the developing roller 20Y, and a bias having a polarity higher than that of the developing roller 20Y and having the same polarity as the toner charging polarity is applied to the compaction roller 22Y. For example, a bias of about +600 V is applied to the compaction roller 22Y. Therefore, the toner particles in the liquid developer on the developing roller 20Y move toward the developing roller 20Y when passing through the nip with the compaction roller 22Y as shown in FIG. As a result, the toner particles are gently coupled to form a film, and when developing with the image carrier 10Y, the toner particles move from the developing roller 20Y to the image carrier 10Y quickly, and the image density is improved. To do.

  The image carrier 10Y is made of amorphous silicon. The surface of the image bearing member 10Y is charged to about + 600V by the anti-static roller 11Y upstream of the nip portion with the developing roller 20Y, and then the latent image is set so that the potential of the image portion becomes + 25V by the exposure unit 12Y. An image is formed. In the developing nip portion formed between the developing roller 20Y and the image carrier 10Y, the bias + 400V applied to the developing roller 20Y and the latent image (image portion + 25V, non-image portion + 600V) applied to the image carrier 10Y. According to the formed electric field, as shown in FIG. 4, the toner particles T are selectively moved to the image portion on the image carrier 10Y, whereby a toner image is formed on the image carrier 10Y. Further, since the carrier liquid C is not affected by the electric field, as shown in FIG. 4, it is separated at the exit of the developing nip between the developing roller 20Y and the image carrier 10Y, and both the developing roller 20Y and the image carrier 10Y are separated. Adhere to. The image carrier 10Y that has passed through the development nip passes through the image carrier squeeze roller 13Y, and the excess carrier liquid C is removed as shown in FIG. 5 to increase the toner particle ratio in the visible image. The

  Next, the image carrier 10Y passes through the nip portion with the intermediate transfer body 40 in the primary transfer 50Y, and the primary transfer of the visible toner image to the intermediate transfer body 40 is performed. The primary transfer roller 51Y is applied with about −200 V having the opposite polarity to the charging characteristics of the toner particles, so that the toner is primarily transferred from the image carrier 10Y to the intermediate transfer member 40, and the carrier liquid is transferred to the image carrier 10Y. Only remains. On the downstream side in the rotation direction of the image carrier 10Y from the primary transfer portion, after the primary transfer, the electrostatic latent image in the image carrier 10Y is erased by the latent image eraser 16Y composed of a lamp or the like and remains on the image carrier 10Y. The carrier liquid is scraped off by the image carrier cleaning blade 17Y and recovered by the developer recovery unit 18Y.

  The toner image primarily transferred onto the intermediate transfer member 40 by the primary transfer unit 50Y passes through the intermediate transfer member squeeze device 52Y in order to scrape excess carriers on the intermediate transfer member 40. + 400V is applied to the intermediate transfer member squeeze roller 53Y of the intermediate transfer member squeeze device 52Y, and + 200V is applied to the intermediate transfer member squeeze backup roller 54Y, and an electric field is generated to press the toner particles against the intermediate transfer member 40 side. Yes. Therefore, toner particles are not collected on the intermediate transfer member squeeze roller 53Y as shown in FIG. 6, and only the carrier liquid that is not affected by the electric field is transferred between the intermediate transfer member 40 and the intermediate transfer member squeeze roller 53Y. Collected by crying.

  The toner image on the intermediate transfer member 40 then proceeds to the secondary transfer unit 60 and enters the nip portion between the intermediate transfer member 40 and the secondary transfer roller 61. The nip width at this time is set to 3 mm. In the secondary transfer unit 60, −1200 V is applied to the secondary transfer roller 61 and +200 V is applied to the belt driving roller 41, whereby the toner image on the intermediate transfer member 40 is a recording medium such as paper. Is transferred to.

  After passing through the secondary transfer unit 60, the intermediate transfer member 40 advances to the winding portion of the tension roller 42, and the toner particles are pressed against the intermediate transfer member 40 by the intermediate transfer member compaction roller 43. The cleaning on the intermediate transfer body 40 is performed by the cleaning blade 46, and again goes to the primary transfer unit 50.

  Next, the squeeze function of the secondary transfer roller 61 will be described. The sheet material is supplied in accordance with the timing at which the toner image overlaid on the intermediate transfer body 40 reaches the secondary transfer portion, and the toner image is secondarily transferred to the sheet material to proceed to a fixing step (not shown). When the final image formation on the sheet material is completed, but a sheet material supply trouble such as a jam occurs, the toner image is transferred in contact with the secondary transfer roller 61 without the sheet material interposed therebetween. Causes backside contamination. The secondary transfer roller 61 according to the present embodiment uses a plurality of photoconductors as means for improving the secondary transfer characteristics following the non-smooth sheet material surface, even if the surface is a non-smooth sheet material due to fibers or the like. An elastic roller having a surface coated with an elastic body for the same purpose as the elastic belt employed in the intermediate transfer body 40 that sequentially transfers the formed toner images, sequentially carries them, and carries them together to carry out secondary transfer onto the sheet material. It is composed. The secondary transfer roller cleaning blade 62 is provided as means for removing the developer (toner dispersed in the carrier) transferred to the secondary transfer roller 61, collects the developer from the secondary transfer roller 61, and is pooled. . Note that the pooled developer is in a mixed color state and may contain foreign matters such as paper dust.

  Next, the cleaning device for the intermediate transfer member 40 will be described. When a sheet material supply trouble such as a jam occurs, not all the toner images are transferred to the secondary transfer roller 61 and collected, and a part remains on the intermediate transfer body 40. Further, even in a normal secondary transfer process, the toner image on the intermediate transfer member 40 is not 100% secondary transferred and transferred to the sheet material, and a secondary transfer residue of several percent occurs. The two types of unnecessary toner images are an intermediate transfer body compaction roller 43 disposed so as to abut on the intermediate transfer body 40 for the next image formation, and the intermediate transfer body compaction roller 43 moves downstream in the moving direction of the intermediate transfer body 40. The intermediate transfer member cleaning blade 46 and the developer recovery unit 47 disposed on the side collect and pool. At this time, a bias is applied to the intermediate transfer body compaction roller 43 so as to press the residual toner on the intermediate transfer body 40 against the intermediate transfer body 40.

  Next, the cleaning mechanism of the elastic roller member will be described. FIG. 7 is an enlarged view of a main part for explaining the cleaning mechanism of the elastic roller member, FIG. 8 is an enlarged view of the main part for explaining the angle of the blade, the pressing force relationship and the mechanism at the cleaning part, 71 is an elastic roller, 71a is A roller base material, 71b is an elastic body, 72 is a cleaning blade, 72a is a blade base material, and 72b is a blade surface layer.

  The cleaning conditions for the developer cleaning of the elastic rollers arranged in various places in the present embodiment are as follows. The toner is developed by applying an electric field from the compaction roller 22Y or the corona discharger to the developing roller 20Y carrying the uniformly dispersed toner on the carrier. Cleaning of the developing roller 20Y that cleans the so-called compacted developer moved to the roller 20Y side and aggregated is the most severe.

  On the other hand, the average particle diameter (number average) of the toner particles is about 1 μm, whereas the surface of such an elastic roller has a surface roughness Rz of about 2 μm, which is rough compared to the average particle diameter of the toner particles. . For this reason, when each toner particle is present on the surface of the elastic roller in an isolated manner, it is difficult to clean the individual toner particles. However, due to compaction, a plurality of toner particles are collected. If so, there is also an aspect that it is easy to clean by the cleaning method of the present invention.

  Hereinafter, the compacted developer cleaning of the developing roller 20Y whose surface is covered with an elastic body will be described as an example. However, the operation and effect are also applied to the cleaning of the developer of the elastic roller disposed in another part. It is.

  In FIG. 7, when the elastic body 71 b of the elastic roller 71 is pressed by the leading edge of the cleaning blade 72, the elastic body 71 b is recessed 73 at the pressing portion as shown in the figure, and this recessed volume is moved by volume to move the elastic roller 71. Elastic deformation is performed to form a protrusion 74 protruding from the circular reference diameter on the upstream side in the rotation direction. When the elastic roller 71 is rotated in the direction of the arrow with respect to the fixed cleaning blade 72, the toner particles T of the developer carried on the surface of the elastic body 71b move from the circular reference diameter of the elastic body 71b to the convex portion. In the transition part 75, the compressive stress is received in the circumferential direction, and the elastic body 71b is stretched to be opened in the circumferential direction as it further shifts to the protruding end part. For this reason, the toner particles T enter the portion where the cleaning blade 72 is pressed and slidably contacted with the surface of the elastic body 71b in a state where the adhesion force to the surface of the elastic body 71b is reduced due to the stress in the circumferential compression and release. Since it becomes easy, a good cleaning function can be exhibited.

  In FIG. 8, the cleaning blade 72 moves the surface of the elastic body 71b with the pressing sliding contact force P (the direction P in the figure is the direction of the reaction force generated by the elastic body 71b with respect to the pressing sliding contact). The elastic body 71b is elastically deformed as shown in FIG. The elastic deformation shape of the elastic body 71b is determined by the relative relationship between the elastic hardness of the elastic body 71b and the hardness of the cleaning blade 72, or the contact posture.

  A vertical line (a line parallel to the tangent on the outer periphery of the elastic roller 71) perpendicular to the generatrix (center line passing through the rotation axis) φ of the elastic roller 71 at the press-sliding contact point where the protruding end of the cleaning blade 72 is in pressure-sliding contact ) The angle formed by the contact surface of the cleaning blade 72 with respect to ν is θ, the cleaning blade 72 presses and slides against the elastic roller 71 to elastically deform the elastic body 71b, and the rising shape of the deformed portion of the elastic 71b is the vertical If the angle formed with the line ν is α, the angle α increases in proportion to the softness of the elastic body of the elastic roller 71, and conversely, the angle α decreases in proportion to the hardness, and the elastic roller 71 is a rigid roller. In this case, α = 0 °. Thus, the elastic deformation amount of the elastic body 71b increases in proportion to the softness of the elastic body of the elastic roller 71, so that the developer carried on the surface of the elastic roller 71 is compressed and released in the circumferential direction. When the stress of the toner particles increases, the adhesion force of the toner particles to the surface of the elastic body 71b decreases and the toner particles are easily detached from the surface of the elastic body 71b. When the hardness of the elastic body is decreased, a good cleaning function can be obtained.

  On the other hand, the cleaning blade 72 may be a rigid rigid body or an elastic body, but in order to form a desired pressing / sliding force, a mechanism for configuring the pressing / sliding force in the case of a rigid rigid body. However, in the case of an elastic body, the pressing sliding contact force can be configured according to the amount of bending of the cleaning blade 72, and the structure is simple. In the present embodiment, the structure of the simple elastic cleaning blade 72 will be described as an example, but basically, the hardness of the cleaning blade 72 is relatively higher than the hardness of the elastic body of the elastic roller. The elastic body 71b of 71 is elastically deformed according to the magnitude of the pressing sliding contact force P.

  In FIG. 8, when the elastic body 71b of the elastic roller 71 is deformed in accordance with the magnitude of the pressing sliding contact force P, when the elastic roller is rotated in the direction of the illustrated arrow, the elastic deformation portion of the elastic body 71b has a rising shape. A force F acts in the vertical direction toward the cleaning blade 72. From P and F, the rotational load of the elastic roller 71 is f and q acting in the direction perpendicular to the bus φ. Here, f = Fcos β, β = 90−α, and q is a state in which the cleaning blade 72 is pressed and slidably contacted with the elastic body 71b of the elastic roller 71 to rotate the elastic roller 71, The rotational load direction of the frictional force of the cleaning blade 72 is a force acting in the direction perpendicular to the bus bar φ at the press sliding contact. Further, the direction in which F acts is a direction perpendicular to the rising shape of the elastic deformation portion of the elastic body 71b, but the magnitude of this force depends on the frictional force between the cleaning blade 72 and the elastic member, similarly to q. .

  If the linear pressure that the cleaning blade 72 presses against the elastic body 71b of the elastic roller 71 is 10 gf / cm or less, a cleaning failure such as scraping occurs, and if it is 80 gf / cm or more, the driving torque becomes large. A range of 80 gf / cm is preferred. In particular, a preferable linear pressure is 40 gf / cm.

  As Example 1, the elastic body 71b is formed of a rubber material such as polyurethane rubber, urethane rubber, silicon rubber, or NBR that can easily control the rubber hardness, and the rubber hardness is preferably set to JIS A 30 to 50 degrees. Deformation is obtained and a good cleaning function can be exhibited.

  As Example 2, in order to facilitate more preferable elastic deformation, the elastic body 71b is formed of a foam material obtained by foaming a rubber material such as polyurethane rubber, silicon rubber, or NBR at a required foaming rate, and the foam material. When the hardness of ASKER C is set to 30 to 50 degrees (corresponding to JIS A 10 to 20 degrees), a more preferable elastic deformation can be obtained, and a better cleaning function can be exhibited. As a means for reducing the friction coefficient of the rubber surface, a tube having a thickness of 3 to 10 μm is covered with a fluorine resin such as PFA or PTFA having a smaller friction coefficient than the rubber material, or a nylon resin. Correspondingly, a surface layer covering the foamed cells is formed. As a result, the frictional force with which the cleaning blade 72 is pressed and slidably contacted is reduced, and the adhesion force by which the toner particles are adhered and supported on the surface of the elastic roller is also reduced, so that a better cleaning function can be exhibited. The hardness of the surface layer coated with the tube is preferably set to ASKER C 40 to 60 degrees (equivalent to JIS A 10 to 25 degrees).

  As Example 3, the elastic body 71b is formed of a rubber material such as polyurethane rubber, urethane rubber, silicon rubber, or NBR that can easily control the rubber hardness, and the rubber hardness is preferably set to JIS A30 to 50 degrees. Deformation is obtained and a good cleaning function can be exhibited. As a means for reducing the friction coefficient of the rubber surface, a fluorine resin such as PFA or PTFA having a smaller friction coefficient than the rubber material, or a nylon resin is coated to a thickness of 3 to 5 μm, or 3 to 10 μm. Corresponding to cover the tube of thickness. As a result, the frictional force with which the cleaning blade 72 is pressed and slidably contacted can be reduced, and the adhesion force that the toner particles are adhered to and supported on the surface of the elastic roller can also be reduced, thereby exhibiting a good cleaning function. The hardness of the surface layer to which coating or tube coating is applied is preferably set to JIS A35 to 55 degrees.

  Further, in Example 4, as the elastic body 71b, from the inner diameter of the roller toward the outer diameter, from the low density foamed portion (foam portion) to the non-foamed portion (solid surface layer portion) of the same material as the foamed portion. ) Is used. In such an elastic body 71b, the foam part and the solid surface part are made of a continuous phase of the same material, and there is no substantial interface between them. As the foam member, a flexible foam material is suitable, and polyurethane foam, polystyrene foam, polyethylene foam, elastomer foam, rubber foam, and the like can be used. When the hardness of the solid surface layer portion is set to ASKER C30 to 50 degrees (equivalent to JIS A10 to 20 degrees), preferable elastic deformation can be obtained. In addition to the reaction injection molding method, a gas mixing method, a foaming agent decomposition method, a solvent diffusion method, a chemical reaction method, a sintering method, an elution method, and the like can be used as a method for producing the foamed member. For more details, reference can be made to, for example, the description of JP-A-5-46020.

  Next, countermeasures on the cleaning blade 72 side as means for reducing the rotational load of the elastic roller will be described.

  As Example 1, the cleaning blade 72 made of an elastic body is formed of polyurethane rubber, and the rubber hardness is set to JIS A 60 to 100 degrees. As a result, it is possible to obtain a desired pressing / sliding force by performing preferable elastic deformation. That is, by making the hardness of the cleaning blade 72 relatively higher than the hardness of the elastic body 71b of the elastic roller 71 described above, the elastic body 71b of the elastic roller 71 is uniquely deformed in accordance with the pressure sliding contact force. As a means for reducing the friction coefficient of the rubber surface, a fluorine-based resin such as PFA or PTFA having a smaller friction coefficient than the rubber material is fixed to the pressing sliding contact surface with the elastic body 71b. However, when the friction reduction measure is taken on the surface of the elastic roller 71 as described above, this measure is not essential. It is possible to obtain a pressing sliding contact force with a desired thickness even if the rubber hardness is less than JIS A 60 degrees with respect to the hardness of the cleaning blade 72, but it is not preferable because microvibration: chatter is generated at the pressing sliding contact portion.

  In the second embodiment, a rigid rigid cleaning blade 72 is formed of a stainless steel plate, and a desired pressing sliding contact force is configured by pressing means such as a spring (not shown). Accordingly, the hardness of the cleaning blade 72 is relatively higher than the hardness of the elastic body of the elastic roller 71 described above, and the elastic body 71b of the elastic roller 71 is uniquely deformed according to the pressing sliding contact force. As a means for reducing the friction coefficient on the surface of the stainless steel plate, fluorine resin such as PFA or PTFA having a friction coefficient smaller than that of the stainless steel plate material is fixed to the pressing sliding contact surface with the elastic body 71b. However, this countermeasure is not indispensable when a friction reducing measure is applied to the elastic roller surface as described above.

  The angles θ and α are set to the following values. The angle θ is set so that the projecting end portion of the cleaning blade 72 is preferentially slidably contacted with the elastic body 71b of the elastic roller 71, and the pressing slidable contact force of the projecting end portion is maximized, specifically 6 ° to 30 °. If it is set within this range, preferable developer cleaning characteristics can be obtained. Here, if the angle is less than 6 °, the pressure sliding contact force in a part away from the tip end part becomes a so-called abdomen press sliding contact, and the pressure sliding contact force in the tip end part is reduced, so that preferable cleaning characteristics cannot be exhibited. On the other hand, when the angle exceeds 30 °, the pressing / sliding force at the protruding end portion of the cleaning blade 72 is extremely concentrated and the elastic body 71b is deformed in a wedge shape, and the rotational load of the elastic roller 71 is large. This is not preferable.

  Further, the angle α increases in proportion to the softness of the elastic body of the elastic roller 71, and conversely decreases in proportion to the hardness. In the case of a rigid rigid roller, θ = 0 °. That is, when the hardness of the elastic roller 71 and the pressing / sliding posture of the cleaning blade 72 are related so that α> θ shown in FIG. 8, a preferable developer cleaning characteristic can be obtained. Conversely, if the hardness of the elastic roller 71 and the pressing / sliding posture of the cleaning blade 72 are related so that α <θ, the rotational load on the elastic roller 71 is not preferable.

  Next, the cleaning mechanism of the intermediate transfer member using the elastic belt member will be described. FIG. 9 is an enlarged view of a main part for explaining a cleaning mechanism performed at a belt winding part, and FIG. 10 is an enlarged view of a main part for explaining a cleaning mechanism performed by a linear moving part of the belt. In the figure, 81 is a roller member, 82 is an elastic belt member, 82a is a belt base material, 82b is an elastic body, 83 is a cleaning blade, 83a is a surface layer, and 84 is a backup roller.

  A cleaning configuration comprising the intermediate transfer member 40, tension roller 42, and intermediate transfer member cleaning blade 46 in FIG. 1, that is, an elastic belt member 82 that moves on the surface shown in FIG. FIG. 8 also shows a cleaning configuration including a roller member 81 that rotates and winds the elastic belt member 82 to guide the elastic belt member 82, and a cleaning blade 83 that presses and slides against the elastic belt member 82 to clean the surface. As described above, the rising angle α of the elastic deformation portion of the elastic body 82b covered on the surface of the elastic belt member 82 is configured such that α> θ with respect to the angle θ formed by the contact surface of the cleaning blade 83. .

  In the secondary transfer process, the intermediate transfer body that sequentially transfers the toner images formed on a plurality of image carriers (photoconductors) in order to be transferred and superposed on each other and then transferred onto the sheet material in a batch. When transferring a toner image to a sheet material, an elastic belt member is used as a means for improving the secondary transfer characteristics following the non-smooth sheet material surface even if the sheet material surface is not smooth due to the fiber. Is adopted. In this case, the belt base of the elastic belt member is a polyimide material, nickel electric pole tube, or stainless steel that has excellent bending durability and is excellent in heat resistance even when there is a heating process in the coating process for covering the elastic body with little elongation due to belt tension. The elastic body covered on the surface is made of a rubber material such as polyurethane rubber, silicon rubber, or NBR with a thickness of about 100 μm to 600 μm. The rubber hardness is set to JIS A 30-50 degrees. By adopting the elastic belt member in this manner, preferable elastic deformation can be obtained and a good cleaning function can be exhibited.

  Then, as means for reducing the friction coefficient of the rubber surface, a fluorine resin such as PFA or PTFA having a smaller friction coefficient than that of the rubber material, or a nylon resin is coated with a thickness of 3 to 5 μm or a thickness of 3 to 10 μm. By covering this tube, the frictional force with which the cleaning blade is pressed and slidably contacted is reduced, and the adhesion force that the toner particles are adhered to and supported on the surface of the elastic roller is also reduced, thereby exhibiting a good cleaning function. it can.

  Further, in order to facilitate preferable elastic deformation, the elastic body to be coated is formed of a foam material obtained by foaming a rubber material such as polyurethane rubber, silicon rubber, or NBR at a required foaming rate, and the hardness of the foam material is ASKER. C30 to 60 degrees (equivalent to JIS A 10 to 25 degrees) is set. As a result, a more preferable elastic deformation can be obtained, and a better cleaning function can be exhibited.

  And, as a means of reducing the friction coefficient of the rubber surface, a tube having a thickness of 3 to 10 μm is covered with a fluorine resin such as PFA or PTFA having a smaller friction coefficient than the rubber material, or a nylon resin. In addition, the surface layer covering the foamed cells is formed to reduce the frictional force with which the cleaning blade is pressed and slidably contacted, and the adhesion force by which the toner particles adhere to and support the elastic roller surface is further reduced, thereby further improving the cleaning function. Can be demonstrated.

  Further, an elastic belt member 82 that covers the surface of the elastic body 82b and moves while supporting the developer as shown in FIG. 10, a cleaning blade 83 that presses and slides to clean the surface, and a pressing slide of the cleaning blade 83. Even in a cleaning configuration including a backup roller (guide member) 84 that backs up from the inside of the elastic belt member 82 at the contact portion and guides the elastic belt member 82 to move linearly, with respect to the angle θ formed by the contact surface of the cleaning blade 83, The rising angle α of the elastic deformation portion of the elastic body 82b coated on the surface of the elastic belt member 82 is configured in a relationship of α> θ. In this case, the elastic belt member 82 has the same contents as in the configuration of FIG. Further, the backup roller 84 as a guide member is composed of a roller member that rotates at the same speed as the elastic belt member 82, and has a structure that reduces the movement resistance of the elastic belt member 82, but the rotating roller member is essential. Instead, it may be a non-rotating roller member, for example, a simple flat fixing member. Preferably, in order to reduce the frictional resistance at the portion where the elastic belt member 82 slides and moves, a fluorine resin such as PFA or PTFA having a smaller friction coefficient than the material of the member is coated.

1 is a diagram illustrating main components constituting an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a cross-sectional view illustrating main components of an image forming unit and a developing unit. It is a figure explaining the compaction by the compaction roller 22Y. It is a figure explaining the development by the developing roller 20Y. It is a figure explaining the squeeze effect | action by the image carrier squeeze roller 13Y. It is a figure explaining the squeeze action by the intermediate transfer body squeeze device 52Y. It is a principal part enlarged view explaining the cleaning mechanism of an elastic roller member. It is a principal part enlarged view explaining the angle of a blade in a cleaning part, pressing force relation, and a mechanism. It is a principal part enlarged view explaining the cleaning mechanism performed in the winding part of a belt. It is a principal part enlarged view explaining the cleaning mechanism performed in the linear moving part of a belt.

Explanation of symbols

10Y, 10M, 10C, 10K ... image carrier, 11Y, 11M, 11C, 11K ... charging roller, 12Y, 12M, 12C, 12K ... exposure unit, 13Y ... image carrier squeeze roller, 14Y: Image carrier squeeze roller cleaning blade, 15Y: Developer recovery unit, 16Y: Latent image eraser, 17Y: Image carrier cleaning blade, 18Y ... Developer recovery unit, 20Y, 20M, 20C, 20K ... developing roller, 21Y ... developing roller cleaning blade, 22Y ... compaction roller, 23Y ... compaction roller cleaning blade, 30Y, 30M, 30C, 30K ... developing unit, 31Y , 31M, 31C, 31K ... developer container, 32Y, 32M, 32C, 32 ... Developer supply roller, 31Y, 31M, 31C, 31K ... Developer container, 33Y ... Regulator blade, 21Y, 34Y ... Agitating roller, 40 ... Intermediate transfer member, 41, 42 ..Belt drive roller, 43... Intermediate transfer body compaction roller, 44... Intermediate transfer body compaction roller cleaning blade, 45... Developer recovery section, 46.・ Developer recovery unit, 50Y, 50M, 50C, 50K ... primary transfer unit, 51Y, 51M, 51C, 51K ... primary transfer backup roller, 52Y, 52M, 52C, 52K ... intermediate transfer member squeeze unit 53Y ... Intermediate transfer member squeeze roller, 54Y ... Intermediate transfer member squeeze backup roller, 55Y ... Medium Transfer body squeeze roller cleaning blade, 56Y ... developer recovery unit, 60 ... secondary transfer unit, 61 ... secondary transfer roller, 62 ... secondary transfer roller cleaning blade, 63 ... development Agent recovery unit

Claims (5)

A latent image formed on the image carrier is developed by a developing roller and transferred from the image carrier to an intermediate transfer member at a transfer position of a primary transfer portion, and then recorded from the intermediate transfer member to a transfer position of a secondary transfer portion. In an image forming apparatus using a liquid developer transferred to
The developing roller having an elastic surface layer is used to perform cleaning by bringing the developing roller cleaning blade into contact with the developing roller, and the developing roller is provided with a compaction mechanism, and the elastic surface layer moves from the inner diameter of the roller toward the outer diameter. Accordingly, an image forming apparatus having a hardness ASKER C of 30 to 50 degrees which is a high-density non-foamed portion made of the same material as the foamed portion is used from the low-density foamed portion. The image forming apparatus according to claim 1, wherein the material is polyurethane foam, polystyrene foam, polyethylene foam, elastomer foam, or rubber foam.   The image forming apparatus according to claim 1, wherein the developing roller cleaning blade uses polyurethane rubber having a hardness of JIS A 60 to 100 degrees. 4. The image forming apparatus according to claim 1, wherein a fluorine-based resin is fixed to a surface of the developing roller cleaning blade that presses and contacts the developing roller. 5. When the angle formed by the contact surface of the developing roller cleaning blade with respect to a vertical line perpendicular to the generatrix of the developing roller at the pressing sliding contact where the protruding end of the developing roller cleaning blade presses and contacts the developing roller is θ, θ is The image forming apparatus according to claim 1, wherein the image forming apparatus is 6 ° to 30 °.

Images