JP4849214B2 - Developing device and image forming apparatus - Google Patents

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. Thus, the carrier liquid is a component necessary for toner storage, toner conveyance, development, and transfer processes. The amount of the carrier liquid is preferably adjusted according to the type of the recording medium when transferring from the intermediate transfer body to the recording medium at the transfer position of the secondary transfer portion. In other words, the surface roughness of the fibers of paper such as paper that is difficult to absorb the carrier liquid, paper that has a smooth surface, and that has a high degree of surface coating (a large amount of coating agent is applied) and recycled paper. It is desirable to adjust the amount of carrier at the secondary transfer position according to the type of paper, such as rough paper that is easy to absorb the carrier liquid, and plain paper that is about halfway between coated paper and rough paper. .

Patent Document 1 (Japanese Patent Application Laid-Open No. 2003-91161) discloses that a carrier removal amount adjustment is performed by a squeeze roller provided on a latent image carrier as a method for making the carrier removal amount variable depending on the paper type. Has been. As a specific method for adjusting the carrier removal amount, an adjustment method by changing the nip width between the squeeze roller and the latent image carrier, and an adjustment by changing the bias difference between the squeeze roller and the latent image carrier. And an adjustment method by changing the pressure of the cleaning blade on the squeeze roller.
JP 2003-91161 A

  By the way, when trying to adjust the carrier removal amount by the method disclosed in Patent Document 1, the toner image is pressed onto the latent image carrier by a physical force, or the toner image by an electric force (electric field). The bias is applied to the image, so that the developed and visualized thin lines are thick, the image is distorted and the transfer to the intermediate transfer member is defective. There was a problem. Further, in the adjustment by changing the pressure of the cleaning blade on the squeeze roller, the fog toner removed from the non-image portion also adheres, so that the image disturbance caused by the fog toner is caused. there were.

  SUMMARY OF THE INVENTION The present invention is to solve the above-mentioned problems. In the invention according to claim 1, the latent image formed on the image carrier is developed by a developing roller and is intermediate from the image carrier at the transfer position of the primary transfer portion. In an image forming apparatus using a liquid developer that is transferred to a transfer body and transferred from the intermediate transfer body to a recording medium at a transfer position of a secondary transfer portion, toner compression that contacts the developing roller and presses the toner toward the developing roller A roller is provided, and the toner compression roller is provided with a carrier amount adjusting means for changing the amount of carrier removed from the toner compression roller according to the type of recording medium on which an image is to be formed. And

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the carrier amount adjusting means is a blade capable of changing a contact state with the toner compression roller.

  According to a third aspect of the present invention, in the image forming apparatus according to the first aspect, the carrier amount adjusting means is a blade capable of changing a pressing state against the toner compression roller.

  According to a fourth aspect of the present invention, in the image forming apparatus according to the first aspect, the carrier amount adjusting means is a roller capable of changing a pressing state with respect to the toner compression roller.

  According to a fifth aspect of the present invention, in the image forming apparatus according to the first aspect, the carrier amount adjusting means is an air knife that jets compressed air to the toner compression roller.

  According to a sixth aspect of the present invention, in the image forming apparatus according to any one of the first to fifth aspects, the carrier amount adjusting means is used as an adjusting mechanism according to the type of recording medium on which an image is to be formed. Only is provided.

  According to the present invention, the fiber texture of paper such as paper having a smooth surface that is difficult to absorb the carrier liquid, coated paper having a high degree of surface coating (a large amount of coating agent is applied), recycled paper, and the like. Adjustment of the amount of carrier placed on the toner compression roller according to the type of paper, such as rough paper that is easy to absorb carrier liquid with large roughness, and plain paper with carrier liquid absorption in the middle of coated paper and rough paper Since the amount of carrier is adjusted by the means, compared to the conventional method of adjusting the amount of carrier in the process after the development process, the optimal secondary transfer conditions according to the paper type are obtained without causing image distortion. Secondary transfer can be performed.

  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.

  Further, the tension roller 42 exceeds the intermediate transfer body 40 together with the belt driving roller 41, and the intermediate transfer body cleaning blade 46, the developer recovery unit, and the tension roller 42 are stretched around the tension roller 42 of the intermediate transfer body 40. A cleaning device 47 is abutted and arranged.

  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 toner compression roller 22Y, FIG. 4 is a diagram for explaining development by the developing roller 20Y, FIG. 5 is a diagram for explaining squeezing action by the image carrier squeeze roller 13Y, and FIG. 6 is an intermediate transfer member. It is a figure explaining the squeeze effect | action by the squeeze 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. The developing unit 30Y includes a cleaning blade 21Y, a developer supply roller 32Y using an anilox roller, and a toner compression roller 22Y on the outer periphery of the developing roller 20Y. A carrier amount adjusting blade 23Y is provided on the outer periphery of the toner compression roller 22Y. Further, a liquid developer stirring roller 34Y and a developer supply roller 32Y are accommodated in the liquid developer container 31Y. 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 toner compression 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 20%, a developing roller 20Y that carries the liquid developer, a liquid developer, and the like. The developer supplying roller 32Y, the regulating blade 33Y, the stirring roller 34Y, and the liquid developer carried on the developing roller 20Y for stirring and maintaining the agent in a uniform dispersed state and supplying it to the developing roller 20Y are brought into a compacted state. It has a developing roller cleaning blade 21Y for cleaning the toner compression roller 22Y and the developing roller 20Y.

  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 20%.

  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 toner compression roller 22Y is a cylindrical member and is in the form of an elastic roller formed by covering an elastic body 22-1Y like the developing roller 20Y as shown in FIG. For example, as shown in FIG. 2, it rotates clockwise in the direction opposite to the developing roller 20Y. The toner compression roller 22Y has means for increasing the charging bias on the surface of the developing roller 20Y. The developer conveyed by the developing roller 20Y is slidably contacted by the toner compression roller 22Y as shown in FIGS. An electric field is applied from the toner compression roller 22Y side toward the developing roller 20Y at a compaction site for forming the toner. The electric field applying means for compaction may be corona discharge from a corona discharger instead of the roller shown in FIG.

  With this toner compression 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 carrier amount adjusting blade 23Y, joined with the developer in the reservoir 31Y, and reused. The amount adjusting blade 23Y will be described in detail in the second half, while the developer D carried and compacted by the developing roller 20Y has a developing nip portion where the developing roller 20Y contacts the image carrier 10Y as shown in FIG. In FIG. 2, the development is performed corresponding to the latent image of the image carrier 10Y by applying a desired electric field. Is recycled and joins are scraped off by the roller cleaning blade 21Y into the developer in the reservoir 31Y. 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 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 excess carrier, and the intermediate transfer body squeeze roller is operated by the action of the cleaning blade. 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. In the liquid development image forming apparatus using the developer in which the toner is dispersed in the carrier of the present embodiment, the developer in which 20% of the toner is dispersed in 80% of the carrier by the approximate weight ratio is used. After the process, the toner weight ratio (solid content ratio) at the position immediately before the secondary transfer to the sheet material, that is, the so-called secondary transfer position is about 45% in the case of smooth paper such as coated paper, In this case, the control is performed with a target of around 55%, and around 60% in the case of rough paper with a coarse fiber fiber such as recycled paper. 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 20%. However, in the case of development with a high image duty in the development on the image carrier 10Y, the toner 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 approximately 20%. 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 when the toner dispersion weight ratio increases, a predetermined amount of carrier is replenished from the carrier cartridge to control the toner to approximately 20% 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 toner compression 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 that of the toner is applied to the toner compression roller 22Y. For example, a bias of about +600 V is applied to the toner compression 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 toner compression 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 body 40 proceeds to the winding portion of the tension roller 42, the intermediate transfer body 40 is cleaned by the intermediate transfer body cleaning blade 46, and the primary transfer section 50 again. Head to.

  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 a 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 collected and pooled by an intermediate transfer member cleaning blade 46 and a developer recovery unit 47 disposed downstream in the moving direction of the intermediate transfer member 40 for the next image formation.

  In the present embodiment, the fibers of paper such as paper with a smooth surface that is difficult to absorb the carrier liquid, coated paper with a high degree of surface coating (a large amount of coating agent is applied), and recycled paper are used. The amount of carrier at the secondary transfer position is changed according to the type of paper, such as rough paper that is easy to absorb carrier liquid with high roughness, and plain paper that absorbs carrier liquid at an intermediate level between coated paper and rough paper. Therefore, a carrier amount adjusting blade 23Y disposed on the toner compression roller 22Y is used.

  More specifically, when the paper type is determined on the print setting on the personal computer, the cartridge in which the paper of the printer main body is loaded, or the setting screen of the control panel of the printer main body, the carrier amount corresponding to the paper type By changing the contact state of the carrier amount adjusting blade 23Y in contact with the toner compression roller 22Y, the carrier amount is adjusted.

FIG. 7 is a view showing the contact state of the carrier amount adjusting blade 23Y with respect to the toner compression roller 22Y, extracted from another configuration. In FIG. 7, θ is an angle defined as the contact angle of the carrier amount adjustment blade 23Y, the extension line (A) of the portion where the carrier amount adjustment blade 23Y is not bent (non-contact portion), and the carrier amount adjustment. This is an angle formed by a tangent line (B) passing through a contact point between the blade 23Y and the toner compression roller 22Y. In the present embodiment, a contact angle changing mechanism for the carrier amount adjusting blade 23Y for changing the contact angle θ is provided. This contact angle changing mechanism is configured to change the contact state between the toner compression roller 22Y and the carrier amount adjusting blade 23Y simultaneously with changing the contact angle. Specifically, the contact state of the carrier amount adjusting blade 23Y with the toner compression roller 22Y and the contact state such as the amount of biting of the carrier amount adjusting blade 23Y at the contact point can be changed. Further, the contact angle changing mechanism has a mode in which the carrier amount adjusting blade 23Y is separated from the toner compression roller 22Y. Table 1 shows the contact angle θ, the contact state, the amount of biting when the carrier amount adjustment blade 23Y is in contact with the toner compression roller 22Y by the contact angle changing mechanism according to the paper type. The carrier amount at the development nip position and the solid content ratio at the development nip position are shown respectively. The development nip is a nip formed by contact between the image carrier 10Y and the development roller 20Y. What is shown in Table 1 is the carrier amount at the development nip and does not indicate the carrier amount at the secondary transfer position. However, as shown in Table 1, the carrier amount at the development nip position is changed according to the paper type. If possible, it can be considered that the carrier amount can be changed according to the change of the carrier amount in the development nip even at the secondary transfer position after the process after the development nip. Processes after the development nip that can cause fluctuations in the carrier amount at the secondary transfer position include a squeeze process at the image carrier squeeze roller 13Y, a primary transfer process at the primary transfer portion for each color of YMCK, and a single transfer process at each color. Although the subsequent squeeze process by the intermediate transfer member squeeze roller can be mentioned, in this embodiment, only the carrier amount adjustment by the carrier amount adjustment blade 23Y in the toner compression roller 22Y is performed. This is because, as shown in the “problem to be solved by the invention”, in the process after the development nip, if the carrier amount is adjusted according to the paper type, the developed image may be disturbed.

表１において、「現像ニップでのキャリア量」とは、現像剤容器３１Ｙ内での現像剤のキャリア量を仮に８０としたときのキャリア量である。現像剤容器３１Ｙ内での現像剤はトナー固形分が２０ｗｔ％、キャリア分が８０ｗｔ％であるので、現像剤容器３１Ｙ内での現像剤のキャリア量を仮に８０と定めるものである。

In Table 1, “the carrier amount at the development nip” is the carrier amount when the carrier amount of the developer in the developer container 31Y is assumed to be 80. Since the developer in the developer container 31Y has a toner solid content of 20 wt% and a carrier content of 80 wt%, the carrier amount of the developer in the developer container 31Y is temporarily set to 80.

  As shown in Table 1, the contact angle changing mechanism is configured such that the carrier amount adjusting blade 23Y contacts the toner compression roller 22Y according to the paper type “coated paper”, “plain paper”, or “rough paper”. In addition, the contact state such as the amount of biting of the carrier amount adjusting blade 23Y at the contact point is changed.

  When the paper type to be printed is “coated paper”, the contact angle changing mechanism sets the contact angle of the carrier amount adjusting blade 23Y to 10 ° and causes the toner compression roller 22Y to contact the edge portion of the carrier amount adjusting blade 23Y. At this time, the carrier amount adjusting blade 23Y is adjusted to bite into the toner compression roller 22Y so that the biting amount is 0.2 mm. Then, the carrier amount at the development nip is 54, and the solid content ratio at the development nip is 27.0%.

  Further, the contact angle changing mechanism sets the contact angle of the carrier amount adjusting blade 23Y to 0 ° when the paper type to be printed is “plain paper”, and the carrier that is a flat portion of the carrier amount adjusting blade 23Y. The abdominal portion of the amount adjustment blade 23Y is brought into contact with the toner compression roller 22Y, and at this time, the carrier amount adjustment blade 23Y is adjusted to bite into the toner compression roller 22Y so that the bite amount is 0.1 mm. Then, the carrier amount at the development nip is 66, and the solid content ratio at the development nip is 23.3%.

  The contact angle changing mechanism separates the carrier amount adjustment blade 23Y from the carrier amount adjustment blade 23Y when the paper type to be printed is “rough paper”. Then, the carrier amount at the development nip is 54, and the solid content ratio at the development nip is 27.0%.

  As described above, in the present embodiment, paper such as paper having a smooth surface that is difficult to absorb the carrier liquid, coated paper having a high degree of surface coating (a large amount of coating agent is applied), recycled paper, and the like. Depending on the type of paper, such as rough paper that has a large fiber grain and is easy to absorb carrier liquid, and plain paper that has an intermediate level of carrier liquid absorption between coated paper and rough paper, it is placed on the toner compression roller 22Y. The contact amount of the carrier amount adjusting blade 23Y can be changed by the contact angle changing mechanism, and the carrier amount is adjusted. Thus, secondary transfer can be performed under optimum secondary transfer conditions according to the paper type without causing image distortion.

  In the above embodiment, the carrier amount is changed according to the paper type by changing the contact state of the carrier amount adjusting blade 23Y disposed on the toner compression roller 22Y by the contact angle changing mechanism. However, an embodiment in which the carrier amount is changed in accordance with the paper type by changing the pressure with which the carrier amount adjusting blade 23Y disposed on the toner compression roller 22Y comes into contact will be described.

  FIG. 8 is a view showing the abutting state of the carrier amount adjusting blade 23Y with respect to the toner compression roller 22Y extracted from another configuration. In FIG. 8, X indicates a direction in which the carrier amount adjusting blade 23Y is moved with respect to the toner compression roller 22Y. In the present embodiment, a contact pressure changing mechanism is provided, and by this contact pressure changing mechanism, the carrier amount adjusting blade 23Y is moved closer to or away from the toner compression roller 22Y in the X direction. The contact pressure of the carrier amount adjusting blade 23Y can be changed.

Table 2 shows the contact pressure, the amount of bite, and the development nip position when the pressure with which the carrier amount adjusting blade 23Y contacts the toner compression roller 22Y is changed by the contact pressure changing mechanism according to the paper type. The carrier amount and the solid content ratio at the development nip position are shown respectively. The definition of the development nip and the definition of “the carrier amount at the development nip” are the same as those described above.

表２で示すものは、現像ニップにおけるキャリア量であり、二次転写位置でのキャリア量を示すものではないが、表２に示すように現像ニップ位置におけるキャリア量を紙種に応じて変更することができれば、現像ニップ以降のプロセスを経た後の、二次転写位置においても、現像ニップにおけるキャリア量の変更に応じて、キャリア量を変更することができるものと考えることができる。二次転写位置におけるキャリア量の変動を発生させ得る、現像ニップ以降のプロセスとしては、像担持体スクイーズローラ１３Ｙでのスクイーズ過程、ＹＭＣＫ各色での一次転写部における一次転写過程、各色の一転写過程後の中間転写体スクイーズローラでのスクイーズ過程が挙げられるが、本実施の形態においては、あくまで、トナー圧縮ローラ２２Ｙにおけるキャリア量調整ブレード２３Ｙによるキャリア量調整のみを行うものとする。なぜなら、「発明が解決しようとする課題」にも示したとおり、現像ニップ以降のプロセスにおいて、紙種に応じてキャリア量の調整を行おうとすると、現像像が乱れる可能性があるからである。このようなことも前述の実施の形態と同様である。

What is shown in Table 2 is the carrier amount at the development nip and does not indicate the carrier amount at the secondary transfer position. However, as shown in Table 2, the carrier amount at the development nip position is changed according to the paper type. If possible, it can be considered that the carrier amount can be changed according to the change of the carrier amount in the development nip even at the secondary transfer position after the process after the development nip. Processes after the development nip that can cause fluctuations in the carrier amount at the secondary transfer position include a squeeze process at the image carrier squeeze roller 13Y, a primary transfer process at the primary transfer portion for each color of YMCK, and a single transfer process at each color. Although the subsequent squeeze process by the intermediate transfer member squeeze roller can be mentioned, in this embodiment, only the carrier amount adjustment by the carrier amount adjustment blade 23Y in the toner compression roller 22Y is performed. This is because, as shown in the “problem to be solved by the invention”, in the process after the development nip, if the carrier amount is adjusted according to the paper type, the developed image may be disturbed. This is also the same as in the previous embodiment.

  As shown in Table 2, the contact pressure changing mechanism causes the carrier amount adjusting blade 23Y to contact the toner compression roller 22Y according to the paper type “coated paper”, “plain paper”, and “rough paper”. The pressure is changed, and the amount of biting of the carrier amount adjusting blade 23Y changes accordingly.

  The contact pressure changing mechanism sets the contact pressure of the carrier amount adjusting blade 23Y to 18 fg / cm when the paper type to be printed is “coated paper”. At that time, the amount of biting of the carrier amount adjusting blade 23Y into the toner compression roller 22Y is 0.2 mm, the amount of carrier in the developing nip is 52, and the solid content ratio in the developing nip is 27.8%.

  Further, the contact pressure changing mechanism sets the contact pressure of the carrier amount adjusting blade 23Y to 5 fg / cm when the paper type to be printed is “plain paper”. At this time, the amount of biting of the carrier amount adjusting blade 23Y into the toner compression roller 22Y is 0.1 mm, the amount of carrier in the developing nip is 65, and the solid content ratio in the developing nip is 23.5%.

  The contact pressure changing mechanism sets the contact pressure of the carrier amount adjusting blade 23Y to 0 fg / cm (that is, the toner compression roller 22Y and the carrier amount adjusting blade 23Y when the paper type to be printed is “rough paper”. And a separated state). At that time, the carrier amount adjusting blade 23Y does not bite into the toner compression roller 22Y, the carrier amount in the developing nip is 80, and the solid content ratio in the developing nip is 20.0%.

  As described above, in the present embodiment, the surface of a paper that is difficult to absorb the carrier liquid, such as a paper with a smooth surface, or a coated paper or a recycled paper with a high degree of surface coating (a large amount of coating agent) is used. Depending on the type of paper, such as rough paper with large fiber grain and easy carrier liquid absorption, or plain paper with carrier liquid absorption in the middle of coated paper and rough paper, it is placed on the toner compression roller 22Y. The carrier amount is adjusted by making the contact pressure of the carrier amount adjusting blade 23Y to be changed by the contact pressure changing mechanism. Thus, secondary transfer can be performed under optimum secondary transfer conditions according to the paper type without causing image distortion.

  In the above embodiment, the carrier amount adjusting blade 23Y disposed on the toner compression roller 22Y is changed in contact state by the contact angle changing mechanism, or the carrier amount adjusting blade 23Y is changed by the contact pressure changing mechanism. The carrier amount is changed according to the paper type by changing the contact pressure. However, in the embodiment of the present invention, the main point is to adjust the carrier amount on the toner compression roller 22Y. Since the carrier amount at the secondary transfer position is adjusted according to the paper type, another carrier amount adjusting means may be provided on the toner compression roller 22Y. Hereinafter, other carrier amount adjusting means will be described.

  A description will be given of an apparatus using a roller as the carrier amount adjusting means. FIG. 9 is a diagram showing the contact state of the carrier amount adjusting roller 24Y with respect to the toner compression roller 22Y extracted from another configuration. In this embodiment, a mechanism for changing the pressing force when the carrier amount adjusting roller 24Y presses against the toner compression roller 22Y is provided, and the nip between the carrier amount adjusting roller 24Y and the toner compression roller 22Y is provided. The pressure can be changed. With this configuration, for example, in the case of coated paper, the nip pressure is increased so that the carrier oil does not pass between the roller nips. In the case of plain paper, the nip pressure is slightly reduced so that the carrier oil passes slightly. In the case of rough paper, the setting is such that all carrier oil passes through the CR and the rollers apart.

  Next, a description will be given of an apparatus using an air knife as a carrier amount adjusting means. FIG. 10 is a diagram showing an arrangement state of the carrier amount adjusting air knife 25Y with respect to the toner compression roller 22Y extracted from another configuration. The present embodiment is characterized in that a carrier amount adjusting air knife 25Y that ejects compressed air toward the toner compression roller 22Y is provided. More specifically, air injection is performed from the slit nozzle of the carrier amount adjusting air knife 25Y over the entire width in the axial direction, and the carrier amount is adjusted by the strength of the injection pressure. For example, in the case of coated paper, the setting is such that the jet pressure is increased and all carrier oil is dropped (does not pass), and in the case of plain paper, the jet pressure is set slightly weak so that the carrier oil passes slightly, In this case, the setting is such that all the carrier oil is allowed to pass without air injection.

Even with the carrier amount adjusting means as described above, the paper that is difficult to absorb the carrier liquid, the paper having a smooth surface, the coated surface having a high degree of surface coating (the coating amount of the coating agent is large), the recycled paper, etc. Optimal secondary transfer according to the type of paper, such as rough paper that has a coarse fiber texture and easily absorbs carrier liquid, and plain paper that has a carrier liquid absorption level intermediate between coated paper and rough paper Conditions can be obtained.

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 toner compression 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 effect | action by the intermediate transfer body squeeze apparatus 52Y. FIG. 6 is a diagram illustrating a contact state of a carrier amount adjustment blade 23Y with a toner compression roller 22Y. FIG. 6 is a diagram illustrating a contact state of a carrier amount adjustment blade 23Y with a toner compression roller 22Y. FIG. 6 is a diagram illustrating a contact state of a carrier amount adjustment roller 24Y with a toner compression roller 22Y. It is a figure which shows the arrangement | positioning state of the carrier amount adjustment air knife 25Y with respect to the toner compression roller 22Y.

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 ... toner compression roller, 23Y ... carrier amount adjusting blade, 24Y ... carrier amount adjusting roller, 25Y ... Carrier amount adjusting air knife, 30Y, 30M, 30C, 30K... Development unit, 31Y, 31M, 31C, 3 K: developer container, 32Y, 32M, 32C, 32K ... developer supply roller, 31Y, 31M, 31C, 31K ... developer container, 33Y ... regulating blade, 21Y, 34Y ... Stirring roller, 40 ... intermediate transfer member, 41, 42 ... belt drive roller, 45 ... developer recovery unit, 46 ... intermediate transfer member cleaning blade, 47 ... developer recovery unit, 50Y , 50M, 50C, 50K ... primary transfer part, 51Y, 51M, 51C, 51K ... primary transfer backup roller, 52Y, 52M, 52C, 52K ... intermediate transfer member squeeze unit, 53Y ... intermediate transfer Body squeeze roller, 54Y... Intermediate transfer body squeeze backup roller, 55Y... Intermediate transfer body squeeze roller cleaning blade, 56Y · Developer collecting portion, 60 ... secondary transfer unit, 61 ... secondary transfer roller, 62 ... secondary transfer roller cleaning blade 63 ... developer collecting section

Claims (14)

A developing roller for developing with a liquid developer containing toner and carrier liquid;
A developer supply member for supplying the liquid developer to the developing roller;
A reservoir for storing the liquid developer supplied to the developer supply member;
A bias applying member that contacts the developing roller and applies a bias to the liquid developer supplied to the developing roller;
A carrier amount adjusting member that adjusts the carrier amount of the liquid developer supplied to the developing roller by contacting the bias applying member;
A drive mechanism for driving the carrier amount adjusting member;
A developing device comprising:   The developing device according to claim 1, wherein the driving mechanism separates the carrier amount adjusting member from the bias applying member.   The developing device according to claim 1, wherein the driving mechanism adjusts a contact angle between the carrier amount adjusting member and the developing roller.   The developing device according to claim 1, wherein the driving mechanism adjusts a contact pressure of the carrier amount adjusting member to the developing roller. A latent image carrier on which a latent image is formed;
A developing roller that develops the latent image formed on the latent image carrier using a liquid developer containing toner and carrier liquid, a developer supply member that supplies the liquid developer to the developing roller, and the developer A storage section for storing the liquid developer supplied to the supply member, a bias applying member that contacts the developing roller and applies a bias to the liquid developer, and a contact member that contacts the bias applying member. A developing unit having a carrier amount adjusting member for adjusting a carrier amount of the supplied liquid developer;
A drive mechanism for driving the carrier amount adjusting member;
A transfer unit for transferring an image developed by the developing unit to a recording medium;
An image forming apparatus comprising: A paper type information input unit for inputting the type of the recording medium transferred by the transfer unit;
The image forming apparatus according to claim 5, wherein the driving mechanism drives the carrier amount adjusting member according to a type of the recording medium input by the paper type information input unit.   The image forming apparatus according to claim 5, wherein the driving mechanism adjusts a contact angle between the carrier amount adjusting member and the developing roller.   The image forming apparatus according to claim 5, wherein the driving mechanism adjusts a contact pressure of the carrier amount adjusting member to the developing roller. The latent image formed on the image carrier is developed by a developing roller, transferred from the image carrier to the intermediate transfer member at the transfer position of the primary transfer portion, and transferred from the intermediate transfer member to the recording medium at the transfer position of the secondary transfer portion. An image forming apparatus using a liquid developer to be transferred,
A toner compression roller that contacts the developing roller and presses the toner to the developing roller side is provided, and the toner compression roller determines the amount of carrier to be removed from the toner compression roller according to the type of recording medium on which an image is to be formed. An image forming apparatus comprising a carrier amount adjusting means for changing. The image forming apparatus according to claim 9, wherein the carrier amount adjusting unit is a blade capable of changing a contact state with the toner compression roller. The image forming apparatus according to claim 9, wherein the carrier amount adjusting unit is a blade capable of changing a pressing state against the toner compression roller. The image forming apparatus according to claim 9, wherein the carrier amount adjusting unit is a roller capable of changing a pressing state with respect to the toner compression roller. The image forming apparatus according to claim 9, wherein the carrier amount adjusting unit is an air knife that jets compressed air to the toner compression roller. The image forming apparatus according to claim 9, wherein only the carrier amount adjusting unit is provided as an adjusting mechanism according to a type of a recording medium on which an image is to be formed. apparatus.

Images