JP2009098397A - Device for removing career liquid and image forming apparatus using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for removing career liquid for preventing turbulence of an image and preventing turbulence of toner particles of an image section by squeeze, and to provide an image forming apparatus using it. <P>SOLUTION: This device for removing career liquid includes a first career liquid removing means 13aY for removing the career liquid on an image carrier for carrying the image by a liquid developer produced by distributing toner particles consisting of a coloring agent and a resin in the career liquid, and a second career liquid removing means 13bY for removing the career liquid on the image carrier after the removal by the first career liquid removing means 13aY. The first career liquid removing means 13aY has an oil-repellency larger than that of the second career liquid removing means 13bY. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a carrier liquid removing apparatus using a liquid toner in which toner is dispersed in a carrier liquid, and an image forming apparatus using the same.

  Conventionally, a squeeze roller has been installed between the development nip and the transfer nip, and a bias close to the surface potential of the toner layer is applied so as not to peel off the toner from the developed toner layer. Discloses a method of removing excess toner floating on the surface (see Patent Document 1).

Further, a method is disclosed in which the removal voltage can be applied without leaking by setting the volume resistance value of the squeeze roller to 10 ⁹ Ω or less (see Patent Document 2).

Further, a method is disclosed in which the solidity concentration in the developer liquid is increased by squeezing to prevent the chargeability of the toner from being deteriorated and the secondary transferability to paper is impaired (patent). Reference 3).
JP 2001-228717 A JP 2002-287518 A JP 2006-30501 A

However, in the technique described in the above-mentioned patent document, the toner particles in the image portion are shifted to the surface of the photoreceptor by squeezing, and the toner particles in the non-image portion are more toner layers on the photoreceptor than the toner particles in the image portion. It had to be floating near the surface. Further, in order to prevent the chargeability of the toner particles from being squeezed on the photoconductor, it is necessary to limit the amount of carrier removal on the photoconductor.

  SUMMARY OF THE INVENTION In order to solve the above problems, an object of the present invention is to provide a carrier liquid removing device that prevents image disturbance and also prevents toner particle disturbance in an image area due to squeeze, and an image forming apparatus using the same. And

The carrier liquid removing device of the present invention is a first carrier liquid removing device that removes a carrier liquid on an image carrier carrying an image by a liquid developer in which toner particles containing a colorant and a resin are dispersed in the carrier liquid. And a second carrier liquid removing means for removing the carrier liquid on the image carrier after being removed by the first carrier liquid removing means, wherein the first carrier liquid removing means comprises the second carrier Since the oil repellency is greater than that of the liquid removing means, the amount of carrier liquid removed is reduced by the first carrier liquid removing means, the toner particles in the image area are aggregated on the surface side of the image carrier, and the second carrier liquid removing means is used. The removal amount of the carrier liquid can be increased, and the fog toner can be reliably removed.

  Further, since the first carrier liquid removing means has a larger contact angle than the second carrier liquid removing means, the amount of carrier liquid removed by the first carrier liquid removing means is reduced, and the toner particles in the image area are image-carrying. It is easy to agglomerate on the surface side of the body, increase the amount of the carrier liquid removed by the second carrier liquid removing means, reliably remove fog toner, and use the contact angle as an indicator of oil repellency. The oil repellency can be measured by various methods.

  Further, since the first carrier liquid removing means and the second carrier liquid removing means have different surface materials, the contact angle and oil repellency can be made different with a simple structure.

  In addition, since the surface material of the first carrier liquid removing means is a fluororesin and the surface material of the second carrier liquid removing means is a urethane resin, the contact angle and oil repellency are different with a simple structure. Can be made.

  Further, since the first carrier liquid removing means and the second carrier liquid removing means have different surface roughnesses, the contact angle and oil repellency can be made different with a simple structure.

  A first cleaning unit that cleans the liquid developer on the first carrier liquid removing unit; and a second cleaning unit that cleans the liquid developer on the second carrier liquid removing unit. Since the first cleaning means has a larger installation angle than the second cleaning means, the cleaning performance of the oil-repellent first carrier liquid removing means and the second carrier liquid removing means is improved, and good cleaning can be achieved even when the amount of carrier liquid is small. Sex can be secured. Further, in the case of an oleophilic roller that easily squeezes the carrier liquid, cleaning can be performed in a state where there is a large amount of the carrier liquid. Therefore, sufficiently good cleaning properties can be maintained even if the cleaning angle is set low.

  Further, an image forming apparatus using the carrier liquid removing device of the present invention includes a developer carrying member that carries a liquid developer, and a transfer member that forms an image by transferring an image on the image carrying member. Therefore, it is possible to form an image with a liquid developer having a stable concentration and to form an image with good image quality.

  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. The developing devices 30Y, 30M, 30C, and 30K, and the developer collection and replenishing devices 100Y, 100M, 100C, and 100K are disposed at the lower portion of the image forming apparatus with respect to the image forming units of the respective colors that are disposed in the center of the image forming apparatus. The intermediate transfer member 40 and the secondary transfer unit 60 are disposed on the upper part of the image forming apparatus.

  The image forming unit includes image carriers 10Y, 10M, 10C, and 10K including photosensitive drums, chargers 11Y, 11M, 11C, and 11K, exposure units 12Y, 12M, 12C, and 12K. The exposure units 12Y, 12M, 12C, and 12K are composed of line heads or the like in which LEDs are arranged, and the image carriers 10Y, 10M, 10C, and 10K are uniformly charged by the chargers 11Y, 11M, 11C, and 11K. The exposure units 12Y, 12M, 12C, and 12K irradiate modulated light based on the input image signals to form electrostatic latent images on the charged image carriers 10Y, 10M, 10C, and 10K. To do.

  The developing devices 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 31Y, 31M, 31C, 31K to be stored, and developer supply rollers 32Y, 32M that supply liquid developers of these colors from the developer containers 31Y, 31M, 31C, 31K to the developing rollers 20Y, 20M, 20C, 20K. , 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.

  In the developing device of this embodiment, the image carriers 10Y, 10M, 10C, and 10K include first image carrier squeeze rollers 13aY, 13aM, 13aC, and 13aK as first carrier liquid removing means that exert a squeeze action on the image carriers 10Y, 10M, 10C, and 10K. The second image carrier squeeze rollers 13bY, 13bM, 13bC, 13bK as the second carrier liquid removing means are in contact with each other, and the developing roller 20Y, 20M, 20C, 20K has a compaction effect on the toner compression device 22Y. , 22M, 22C, and 22K.

  Next, the developer collection and supply devices 100Y, 100M, 100C, and 100K will be described.

  The agitation tanks 70Y, 70M, 70C, and 70K receive high-concentration toner from the high-concentration toner tanks 71Y, 71M, 71C, and 71K through the toner supply paths 83Y, 83M, 83C, and 83K, and the carrier supply paths 84Y, The carrier oil is supplied from the carrier oil tanks 72Y, 72M, 72C, 72K via 84M, 84C, 84K.

  The first image carrier squeeze rollers 13aY, 13aM, 13aC, 13aK and the second image carrier squeeze are passed through the first developer recovery paths 81Y, 81M, 81C, 81K to the stirring tanks 70Y, 70M, 70C, 70K. The liquid developer collected from the rollers 13bY, 13bM, 13bC, 13bK and the developing rollers 20Y, 20M, 20C, 20K is recycled. Note that in the collection paths such as the first developer collection paths 81Y, 81M, 81C, and 81K and the supply paths such as toner supply paths 83Y, 83M, 83C, and 83K and carrier supply paths 84Y, 84M, 84C, and 84K described later. Is provided with forced liquid moving means such as a pump (not shown) as required.

  Here, in the stirring tanks 70Y, 70M, 70C, and 70K, a transmission type photosensor that detects a dispersion weight ratio of the toner (not shown) is provided as a means for detecting the density in order to control the density of the developer. In addition, the stirring tanks 70Y, 70M, 70C, and 70K are provided with stirring devices 75Y, 75M, 75C, and 75K made of fins and the like, and supplied high-concentration toner, carrier oil, and recycled liquid developer. Is stirred. Instead of providing a photosensor for detecting the concentration, a torque detecting means for detecting the stirring torque of a stirring device made of fins or the like may be provided, and the concentration may be detected by this detected torque.

  The liquid developer stirred and adjusted in the stirring tanks 70Y, 70M, 70C, and 70K is supplied to the developer containers (reservoirs) 31Y, 31M, 31C, and 31K via the developer supply paths 80Y, 80M, 80C, and 80K. The

  The concentration control of the liquid developer in the stirring tanks 70Y, 70M, 70C, and 70K is, for example, the consumption of the liquid developer by counting the number of dots of the output image in a controller (not shown) that manages the image signal. The amount of toner is predicted, and the developer concentrations in the developer containers (reservoirs) 31Y, 31M, 31C, and 31K are predicted, and the high-concentration toner tanks 71Y, 71M, and 71C for the stirring tanks 70Y, 70M, 70C, and 70K are predicted. , 71K and the supply amount from the carrier oil tanks 72Y, 72M, 72C, 72K can be predicted and controlled. Such predictive control can improve the control responsiveness and reliability of the image forming apparatus.

  The intermediate transfer member 40 is an endless belt member, is wound around and stretched between the first drive roller 41a, the second drive roller 41b, and the tension roller 42, and images are transferred by the primary transfer portions 50Y, 50M, 50C, and 50K. The roller 10 is rotationally driven by the driving roller 41 while being in contact with the carriers 10Y, 10M, 10C, 10K. 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.

  The secondary transfer unit 60 includes a first secondary transfer device 60a and a second secondary transfer device 60b, and the first secondary transfer roller 61a and the second secondary transfer roller 61b sandwich the intermediate transfer body 40 therebetween. A first cleaning device that is disposed opposite to the first drive roller 41a and the second drive roller 41b, and further includes a first secondary transfer roller cleaning blade 62a and a first developer recovery unit 63a, and a second developer recovery unit A second cleaning device comprising 63b and a second secondary transfer roller cleaning blade 62b is disposed. In the secondary transfer unit 60, the sheet material conveyance path L is synchronized with the timing at which a full-color toner image or a single-color toner image formed on the intermediate transfer body 40 reaches the transfer position of the secondary transfer unit 60. Then, a sheet material such as paper, film or cloth is conveyed and supplied, and a single-color toner image or a full-color toner image is secondarily transferred to the sheet material.

  A fixing unit (not shown) is disposed in the sheet material conveyance path L, and a single color toner image or a full color toner image transferred onto the sheet material is fused and fixed to a recording medium (sheet material) such as paper, The image formation on the final sheet material is finished.

  On the side of the tension roller 42 that stretches the intermediate transfer body 40 together with the belt driving roller 41, a cleaning device including an intermediate transfer body cleaning blade 46 and a developer recovery unit 47 is disposed along the outer periphery thereof. The intermediate transfer body 40 after passing through the unit 60 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 again goes to the primary transfer section 50. .

  Next, the image forming unit and the developing device will be described. FIG. 2 is a sectional view showing main components of the image forming unit and the developing device. 3 is a diagram for explaining the developer supply member, FIG. 4 is a diagram for explaining the compression of the developer by the developer compression device 22Y, FIG. 5 is a diagram for explaining the development by the developing roller 20Y, and FIG. 6 is the first image carrier. FIG. 7 is a diagram for explaining the squeeze action by the second image carrier squeeze roller 13bY, and FIG. 8 is a figure for explaining the squeeze action by the intermediate transfer member squeeze device 52Y. Since the configurations of the image forming units for each color and the developing storage are the same, the following description will be made based on the yellow (Y) image forming unit and the developing device.

  The image forming unit includes a cleaning device including a static eliminator 16Y, an image carrier cleaning blade 17Y, and a developer recovery unit 18Y, a charger 11Y, an exposure unit 12Y, and a developer storage unit 30Y along the rotation direction of the outer periphery of the image carrier 10Y. Developing roller 20Y, and an image carrier squeeze device comprising a first image carrier squeeze roller 13aY, a first cleaning blade 14aY, a second image carrier squeeze roller 13bY, a second cleaning blade 14bY, and a developer recovery unit 15Y. Has been placed.

  In the developing device 30Y, a cleaning blade 21Y and a developer supply roller 32Y using an anilox roller are disposed on the outer periphery of the developing roller 20Y. A liquid developer stirring paddle 34Y and a developer supply are provided in a liquid developer container 31Y. A roller 32Y is accommodated. Further, a developer recovery unit 25Y is provided corresponding to the cleaning blade 21Y, and a pipe for the first developer recovery path 81Y is provided to the developer recovery unit 15Y and the developer recovery unit 25Y for recycling the liquid developer. Is connected.

  Further, 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 arranged 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 charger 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 charged polarity of the developing toner particles is applied from a power supply device (not shown). Then, the image carrier 10Y is charged. The exposure unit 12Y exposes the image carrier 10Y charged by the charger 11Y on the downstream side in the rotation direction of the image carrier 10Y from the charger 11Y, and forms a latent image on the image carrier 10Y.

  The developing device 30Y stirs the developer container 31Y for storing the liquid developer in which the toner is dispersed in a carrier liquid at a weight ratio of about 25%, the developing roller 20Y for carrying the liquid developer, and the liquid developer. The developer supply roller 32Y, the regulating blade 33Y, the agitation paddle 34Y, the developing roller cleaning blade 21Y for cleaning the developing roller 20Y, and the developing roller 20Y for maintaining the uniform dispersed state and supplying the developing roller 20Y. A developer compressing device 22Y for bringing the carried liquid developer into a compressed state is provided.

  The liquid developer accommodated in the developer container 31Y is a low concentration (about 1 to 2 wt%) and low viscosity, which is conventionally used, using Isopar (trademark: Exxon) as a carrier liquid. It is not a volatile liquid developer having volatility, but a non-volatile liquid developer having a high concentration and high viscosity and having non-volatility 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%.

  As shown in FIG. 3, the developer supply roller 32 </ b> Y is a cylindrical member, and an anilox roller having an uneven surface formed by a fine and uniform spiral groove on the surface so as to easily carry the developer on the surface. For example, it rotates counterclockwise as shown in FIG. 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 paddle 34Y and the developer supply roller 32Y may be in sliding contact with each other, but may be 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 liquid developer scraped off here is recycled from the developer recovery section 25Y through the pipe of the first developer recovery path 81Y.

  The developer compressing device 22Y applies corona discharge from a corona discharger. As shown in FIG. 4, the developer compressing device 22Y moves the toner T uniformly dispersed in the carrier liquid C to the developing roller 20Y side and aggregates it to form a so-called developer compressed state T ′. As shown in FIG. 5, the developer D carried by the developing roller 20Y and compressed by the developer is applied to the image carrier 10Y by applying a desired electric field at the developing nip where the developing roller 20Y contacts the image carrier 10Y. Development is performed corresponding to the latent image. The undeveloped developer D is scraped off and removed by the developing roller cleaning blade 21Y, joins the developer in the developer container 31Y, and is reused. Note that the carrier liquid and toner to be merged are not in a mixed color state.

  Next, an image carrier squeeze device as a carrier liquid removing device will be described. The image carrier squeeze device of the present embodiment includes a first image carrier squeeze device and a second image carrier squeeze device, and is disposed on the downstream side of the developing roller 20Y so as to face the image carrier 10Y. It is always in contact with the image carrier 10Y and collects the excess developer of the developed toner image.

  As shown in FIG. 6, the first image carrier squeeze device includes a first image carrier squeeze composed of an elastic roller member that is covered with a first elastic body 13a-1Y and rotates in sliding contact with the image carrier 10Y. As shown in FIG. 2, the roller 13aY includes a first cleaning blade 14aY that presses and slides against the first image carrier squeeze roller 13aY to clean the surface, and a developer recovery unit 15Y.

  Further, as shown in FIG. 7, the second image carrier squeeze device has a second image carrier comprising an elastic roller member that covers the surface of the second elastic body 13b-1Y and rotates in sliding contact with the image carrier 10Y. As shown in FIG. 2, the body squeeze roller 13bY and a second cleaning blade 14bY that presses and slides against the second image carrier squeeze roller 13bY to clean the surface.

  The image carrier squeeze device has a function of collecting excess carrier liquid C and originally unnecessary fog toner T ″ from the developer D developed on the image carrier 10Y, and increasing the toner particle ratio in the visible image. The recovery capability of the carrier liquid C is such that the first image carrier squeeze roller 13aY and the second image are rotated with respect to the rotation direction of the first image carrier squeeze roller 13aY and the second image carrier squeeze roller 13bY and the peripheral speed of the surface of the image carrier 10Y. The desired recovery capability can be set by the relative circumferential speed difference of the surface of the carrier squeeze roller 13bY. When the image carrier 10Y is rotated in the counter direction, the recovery capability is increased. Even if this is set to a large value, the recovery capability is enhanced, and further, this synergistic effect is possible.

  By comprising in this way, much carrier liquid C can be removed and image disorder can be prevented. Further, in the present embodiment, the first image carrier squeeze roller 13aY reduces the removal amount of the carrier liquid C, causes the toner particles in the image area to aggregate on the surface side of the image carrier 10Y, and the second image carrier squeeze roller. The removal amount of the carrier liquid C can be increased by 13bY, and the fog toner can be reliably removed.

The intermediate transfer member squeeze device 52Y is disposed on the downstream side of the primary transfer unit 50Y, and removes excess carrier liquid C from the intermediate transfer member 40 to increase the toner particle ratio in the visible image. A stage in which the carrier liquid amount of the developer (toner dispersed in the carrier) transferred to the intermediate transfer body 40 by the primary transfer unit 50Y is secondarily transferred to the above-described final-stage sheet material and proceeds to a fixing process (not shown). Thus, in order to exhibit a preferable secondary transfer function and fixing function, when the approximate toner weight ratio of the desired dispersion state of the liquid developer does not reach about 40% to 60%, an excess carrier liquid is further removed from the intermediate transfer body 40. Is provided as a means for removing. 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. Continuing, the image forming unit and the developing storage unit will be described by taking the yellow image forming unit and the developing storage unit 30Y out of the four image forming units and the developing storage unit.

  In the developer container 31Y, the toner particles in the liquid developer have a positive charge. The liquid developer is stirred by the stirring paddle 34Y, and the developer supply roller 32Y rotates, whereby the developer container 31Y. Pumped from.

  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 faces the developer compression device 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 that is higher than the developing roller 20Y and has the same polarity as the toner charging polarity is applied to the developer compression device 22Y. For example, a bias of about +600 V is applied to the developer compression device 22Y. Therefore, the toner particles in the liquid developer on the developing roller 20Y move to the developing roller 20Y side when passing through a portion facing the developer compressing device 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 carrier 10Y is charged to about + 600V by the charger 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. 5, 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. 5, 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. As shown in FIGS. 6 and 7, the first image carrier squeeze roller 13aY and the second image carrier squeeze roller 13bY are provided with an excess carrier liquid C and an originally unnecessary fog from the developer D developed on the image carrier 10Y. It has a function of collecting the toner T ″ and increasing the toner particle ratio in the visible image.

  Excess carrier C and unnecessary fog toner T ″ collected by the first image carrier squeeze roller 13aY are collected from the first image carrier squeeze roller 13aY to the developer collecting unit 15Y by the action of the first cleaning blade 14aY. Excess carrier C and unnecessary fog toner T ″ collected by the second image carrier squeeze roller 13bY are collected from the second image carrier squeeze roller 13bY to the developer collecting unit 15Y by the action of the second cleaning blade 14bY. It is recycled through the piping of the first developer recovery path 81Y. Note that since the collected surplus carrier C and fog toner T ″ are collected from the dedicated isolated image carrier 10Y, no color mixing phenomenon occurs at all locations.

  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, the electrostatic latent image of the image carrier 10Y after the primary transfer is erased by the static eliminator 16Y composed of an LED 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 images on the intermediate transfer member 40, which are sequentially transferred by primary transfer of the toner images formed on the plurality of image carriers 10, are then transferred to the secondary transfer unit 60, where the intermediate transfer member 40 and the first and second toner images are transferred. The toner enters the nip portion between the secondary transfer roller 61a and the second secondary transfer roller 61b. In the secondary transfer unit 60, -1200V is applied to the first secondary transfer roller 61a and the second secondary transfer roller 61b, and + 200V is applied to the belt driving roller 41, whereby the intermediate transfer body 40 is applied. The upper toner image is transferred to a recording medium (sheet material) such as paper.

  However, when a sheet material supply trouble such as jam occurs, not all the toner images are transferred to the secondary transfer roll and collected, and a part of the toner image remains on the intermediate transfer body, and the normal secondary image is not recovered. Even in the transfer process, the toner image on the intermediate transfer member is not 100% secondary transferred and transferred to the sheet material, and a secondary transfer residue of several percent occurs. In particular, when a sheet material supply trouble such as a jam occurs, the toner image is transferred in contact with the first secondary transfer roller 61a and the second secondary transfer roller 61b without the sheet material interposed, and the back surface of the sheet material is soiled. cause. In the present embodiment, the first secondary transfer roller applies a bias in the direction in which the toner particles of the liquid developer are pressed against the intermediate transfer body and a bias having the same polarity as the charging polarity of the toner particles to these unnecessary toner images. 61a and the second secondary transfer roller 61b. As a result, the toner particles of the liquid developer remaining on the intermediate transfer body 40 are pressed against the intermediate transfer body 40 to be in a compacted state, and the carrier is transferred to the first secondary transfer roller 61a and the second secondary transfer roller 61b. The liquid is recovered (squeezed), the intermediate transfer member cleaning blade 46 cleans the intermediate transfer member 40, the first secondary transfer roller cleaning blade 62a cleans the first secondary transfer roller 61a, and the second secondary transfer roller cleaning. The second secondary transfer roller 61b is cleaned by the blade 62b.

  Next, the squeeze function of the first secondary transfer roller 61a and the second secondary transfer roller 61b 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 finished, but a sheet material supply trouble such as a jam occurs, the toner image is transferred to the first secondary transfer roller 61a and the second secondary image without the sheet material interposed. It is transferred in contact with the transfer roller 61b and causes the back surface of the sheet material to become dirty. Even if the first secondary transfer roller 61a and the second secondary transfer roller 61b of the present embodiment are sheet materials whose surfaces are not smooth due to fiber or the like, secondary transfer characteristics follow the surface of the non-smooth sheet material. As a means for improving the above, the same purpose as that of the elastic belt employed in the intermediate transfer body 40, in which toner images formed on a plurality of photoconductors are sequentially primary transferred, superimposed and carried, and then secondary transferred onto a sheet material collectively. It is comprised with the elastic roller which coat | covered the elastic body on the surface. The first secondary transfer roller cleaning blade 62a and the second secondary transfer roller cleaning blade 62b are developers (toners dispersed in the carrier) transferred to the first secondary transfer roller 61a and the second secondary transfer roller 61b. The developer is collected from the first secondary transfer roller 61a and the second secondary transfer roller 61b and 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. If a sheet material supply trouble such as a jam occurs, all the toner images are transferred to the first secondary transfer roller 61a and the second secondary transfer roller 61b and are not collected, and a part thereof is an intermediate transfer body. 40 remains. Further, in the normal secondary transfer process, the toner image on the intermediate transfer member 40 is secondarily transferred 100% and is not transferred to the sheet material, and a secondary transfer residue of several percent is generated. The two types of unnecessary toner images are collected by an intermediate transfer member cleaning blade 46 and a developer collecting unit 47 arranged so as to contact the intermediate transfer member 40 for the next image formation. During such non-transfer, a bias is applied to the first secondary transfer roller 61a and the second secondary transfer roller 61b so as to press the residual toner on the intermediate transfer body 40 against the intermediate transfer body 40.

  Next, specific embodiments of the first image carrier squeeze roller 13aY and the second image carrier squeeze roller 13bY will be described.

  In the present embodiment, the first image carrier squeeze roller 13aY has greater oil repellency than the second image carrier squeeze roller 13bY. In this embodiment, a contact angle as shown in FIG. 9 is used as an index indicating oil repellency. The contact angle is defined as an angle formed by drawing a tangent line of the droplet surface at the contact position between the droplet surface and the roller surface and making the tangent line and the roller surface. The contact angle is measured by dropping 0.5 μl of the carrier liquid onto the roller to be measured and measuring the contact angle using Drop Master 500 manufactured by Kyowa Interface Chemical Co., Ltd. As described above, by using the contact angle as an index indicating oil repellency, the oil repellency can be measured by a simple method.

  Next, a specific example for making the oil repellency of the first image carrier squeeze roller 13aY and the second image carrier squeeze roller 13bY different in a configuration having a plurality of squeeze rollers as in the present embodiment will be described. To do.

  First, in the first embodiment, the surface materials of the first image carrier squeeze roller 13aY and the second image carrier squeeze roller 13bY are made different. For example, the first image carrier squeeze roller 13aY is coated with a fluorine resin made of a urethane resin containing fluorine as a surface material, and the second image carrier squeeze roller 13bY is coated with a urethane resin as a surface material. In this case, the contact angle of the first image carrier squeeze roller 13aY is 60 °, and the contact angle of the second image carrier squeeze roller 13bY is 30 °.

  In the second embodiment, the surface roughness of the first image carrier squeeze roller 13aY and the second image carrier squeeze roller 13bY is made of the same material. For example, the first image carrier squeeze roller 13aY has a surface roughness of Rz = 5 μm, and the second image carrier squeeze roller 13bY has a surface roughness of Rz = 0.5 μm. In this case, the contact angle of the first image carrier squeeze roller 13aY is 50 °, and the contact angle of the second image carrier squeeze roller 13bY is 30 °.

  Thus, by changing the surface material or surface roughness of the first image carrier squeeze roller 13aY and the second image carrier squeeze roller 13bY, the contact angle and oil repellency can be made different with a simple structure. By making the oil repellency of the first image carrier squeeze roller 13aY greater than the oil repellency of the second image carrier squeeze roller 13bY, the removal amount of the carrier liquid C is reduced by the first image carrier squeeze roller 13aY. Part of the toner particles is agglomerated on the surface side of the image carrier 10Y, and the removal amount of the carrier liquid C is increased by the second image carrier squeeze roller 13bY, so that the fog toner can be reliably removed.

  Next, a cleaning device for the first image carrier squeeze roller 13aY and the second image carrier squeeze roller 13bY will be described. In the present embodiment, the installation angle of the first cleaning blade 14aY is made larger than the installation angle of the second cleaning blade 14bY. For example, the installation angle of the first cleaning blade 14aY is 30 °, and the installation angle of the second cleaning blade 14bY is 20 °.

  Thus, by installing the first cleaning blade 14aY and the second cleaning blade 14bY, the cleaning performance of the oil-repellent first image carrier squeeze roller 13aY and the second image carrier squeeze roller 13bY is improved, and the carrier liquid Good cleaning properties can be ensured even in a state where there is little. Further, in the case of an oleophilic roller that easily squeezes the carrier liquid, cleaning can be performed in a state where there is a large amount of the carrier liquid. Therefore, sufficiently good cleaning properties can be maintained even if the cleaning angle is set low.

1 is a diagram illustrating an embodiment of an image forming apparatus. It is sectional drawing which showed the main components of the image formation part and the developing storage. It is a perspective view of a developer supply member. It is a figure explaining compression of a developer by developer compression device 22Y. It is a figure explaining the development by the developing roller 20Y. It is a figure explaining the squeeze effect | action by the 1st image carrier squeeze roller 13aY. It is a figure explaining the squeeze effect | action by the 2nd image carrier squeeze roller 13bY. It is a figure explaining the squeeze effect | action by the intermediate transfer body squeeze apparatus 52Y. It is a figure explaining a contact angle.

Explanation of symbols

  10Y, 10M, 10C, 10K ... photosensitive body (image carrier), 11Y, 11M, 11C, 11K ... corona charger, 12Y, 12M, 12C, 12K ... exposure unit, 13aY ... first image carrier squeeze roller (first) 1 carrier liquid removing means), 14aY ... first cleaning blade (first cleaning means), 13bY ... second image carrier squeeze roller (second carrier liquid removing means), 14bY ... second cleaning blade (second cleaning means) , 15Y: Developer recovery unit, 16Y: Static elimination device, 17Y ... Photoconductor blade, 18Y ... Photoconductor cleaning liquid recovery unit, 20Y, 20M, 20C, 20K ... Development roller (developer carrier), 21Y ... Development roller blade 30Y, 30M, 30C, 30K ... development storage, 31Y, 31M, 31C, 31K ... developer 32Y, 32M, 32C, 32K ... toner supply roller (developer supply member), 33Y ... toner regulating blade (developer regulating member), 34Y ... stirring paddle (stirring member), 50Y, 50M, 50C, 50K ... primary Transfer backup roller 40... Intermediate transfer member 41 a... First belt drive roller 41 b. Second belt drive roller 42. Tension roller 46 Intermediate transfer belt cleaning blade 47 47 Intermediate transfer belt cleaning liquid recovery unit 50 ... primary transfer part, 51 ... primary transfer roller, 60 ... secondary transfer unit, 61a ... first secondary transfer roller, 61b ... second secondary transfer roller, 62a ... first secondary transfer roller blade, 62b ... second Secondary transfer roller blade, 63a... First secondary transfer roller cleaning liquid recovery unit, 63b. 70N, 70M, 70C, 70K ... stirring tank, 71Y, 71M, 71C, 71K ... high concentration toner tank, 72Y, 72M, 72C, 72K ... carrier oil tank, 75Y, 75M, 75C, 75K ... stirring Apparatus, 80Y, 80M, 80C, 80K ... Developer supply path, 81Y, 81M, 81C, 81K ... First developer recovery path, 83Y, 83M, 83C, 83K ... Toner supply path, 84Y, 84M, 84C, 84K ... Carrier supply path, 100Y, 100M, 100C, 100K ... Developer recovery supply device

Claims (7)

A first carrier liquid removing means for removing the carrier liquid on the image carrier carrying the image by the liquid developer in which toner particles containing a colorant and a resin are dispersed in the carrier liquid;
A second carrier liquid removing means for removing the carrier liquid on the image carrier after being removed by the first carrier liquid removing means,
The carrier liquid removing device according to claim 1, wherein the first carrier liquid removing means has a greater oil repellency than the second carrier liquid removing means. The carrier liquid removing device according to claim 1, wherein the first carrier liquid removing means has a contact angle larger than that of the second carrier liquid removing means.   The carrier liquid removing device according to claim 1 or 2, wherein the first carrier liquid removing means and the second carrier liquid removing means have different surface materials.   4. The carrier liquid removing device according to claim 3, wherein the surface material of the first carrier liquid removing means is a fluorine resin, and the surface material of the second carrier liquid removing means is a urethane resin. .   The carrier liquid removing device according to claim 1 or 2, wherein the first carrier liquid removing means and the second carrier liquid removing means have different surface roughness. First cleaning means for cleaning the liquid developer on the first carrier liquid removing means, and second cleaning means for cleaning the liquid developer on the second carrier liquid removing means,
The carrier liquid removing apparatus according to claim 1, wherein the first cleaning unit has a larger installation angle than the second cleaning unit. 7. A developer carrying body carrying a liquid developer, and a transfer body for forming an image by transferring an image on the image carrying body. An image forming apparatus using the carrier liquid removing device described in 1.

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