JP2007148083A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively remove a foreign matter such as paper powder, dust and residual toner on a transfer roller and a similar foreign matter accumulated and stuck to the transfer roller by using a liquid carrier in liquid developer. <P>SOLUTION: In the image forming apparatus, a foreign matter removal mode is performed to a secondary transfer roller 46 and a secondary transfer roller cleaner 47 when a foreign matter removal mode start condition is formed. In the foreign matter removal mode, a white solid image for cleaning formed on an intermediate transfer belt 10, comprising nonvolatile liquid carrier, and formed longer than the peripheral length of the secondary transfer roller 46 is stuck to all the periphery of the secondary transfer roller 46 from the intermediate transfer belt 10 so that its stuck amount may be larger than that in normal image forming. Much liquid carrier on the secondary transfer roller 46 is removed together with the foreign matter by the secondary transfer roller cleaner 47 made to press-contact with the secondary transfer roller 46. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a toner image obtained by developing an electrostatic latent image with a liquid developer composed of toner and a liquid carrier, for example, on a transfer material such as paper, and carrying the liquid developer image, for example, a photoreceptor, The present invention relates to an image forming apparatus such as a copying machine, a facsimile machine, and a printer, which obtains an image by transfer using a transfer roller that contacts a toner image carrier such as an intermediate transfer belt and an intermediate transfer roller.

In this type of conventional image forming apparatus, yellow Y, magenta M, cyan C, and black K latent image carriers are arranged in tandem along the intermediate transfer belt, and the static images on the latent image carriers are arranged. The electrostatic latent image is developed with a liquid developer in which toner is dispersed in a liquid carrier to form a toner image, a transfer electric field is formed between each latent image carrier and the intermediate transfer belt, and each latent image carrier is formed. The toner particles that form toner images of each color on the body are electrophoresed in a liquid carrier, and are overlaid on the intermediate transfer belt for primary transfer to form a full-color toner image. There is known an image forming apparatus that obtains a full color image by secondary transfer of a toner image onto a transfer material by a secondary transfer roller in contact with an intermediate transfer belt (see, for example, Patent Document 1).
JP 2001-318507 A.

  By the way, in the image forming apparatus disclosed in Patent Document 1, the liquid carrier also adheres to the non-image portions where the toner images of the latent image carriers and the intermediate transfer belt are not formed during image formation. For this reason, for example, paper dust that drops off from the side edge of the paper that is the transfer material adheres to the secondary transfer roller that is in contact with the intermediate transfer belt through the liquid carrier in the non-image portion of the intermediate transfer belt. In addition, toner particles mixed in the liquid carrier in the non-image part and dust in the apparatus also adhere to the secondary transfer roller. Then, when foreign matters such as paper dust, toner particles, and dust adhere to the secondary transfer roller, they accumulate on the secondary transfer roller after a long time has passed. When foreign matter adheres and accumulates on the secondary transfer roller in this way, when a new image is formed, the foreign matter on the secondary transfer roller adheres to the back of the paper, and the paper on which the image is newly formed is attached. It gets dirty. In particular, when image formation is performed using a paper having a width larger than that of paper often used during normal image formation, the paper is significantly stained. In addition, in the double-sided image formation, when an image is formed on the back side of the paper, an image is formed on the foreign matter attached from the secondary transfer roller to the back side of the paper when the image is first formed on the front side of the paper. When the image on the back side of the paper is peeled off, the image on the foreign material is also peeled off, resulting in image omission.

  Therefore, it is conceivable to improve the image quality by bringing a secondary transfer roller cleaner such as a cleaning blade into contact with the secondary transfer roller so as to remove foreign substances attached and deposited on the secondary transfer roller. However, this time, foreign matter adheres and accumulates on the secondary transfer roller cleaner, and the secondary transfer roller cleaner cannot be effectively cleaned by the secondary transfer roller cleaner, and the image quality cannot be improved sufficiently. There is a problem.

  The present invention has been made in view of such circumstances, and the object thereof is to utilize a liquid carrier of a liquid developer used for development, thereby allowing foreign matter such as paper dust, dust, and residual toner on the transfer roller. Another object of the present invention is to provide an image forming apparatus capable of effectively removing the same foreign matter deposited and adhered to the transfer roller.

  In order to solve the above problems, the invention of claim 1 is a liquid developer comprising a latent image carrier on which an electrostatic latent image is formed, and the electrostatic latent image comprising toner and a non-volatile liquid carrier. A developing device that develops and forms a developer image on the latent image carrier and a transfer roller that conveys the developer image on the latent image carrier by a transfer roller that contacts the latent image carrier during image formation. An image forming apparatus comprising at least a transfer device for transferring to a material, wherein the transfer device includes a transfer roller cleaning member that contacts the transfer roller and cleans the transfer roller, and the transfer roller includes the liquid Foreign matter removal that removes foreign matter adhering to the transfer roller and foreign matter adhering to and depositing on the transfer roller cleaning member by attaching a larger amount of carrier than during normal image forming operation With over mode is set, it is characterized by executing the foreign substance removal mode when the foreign substance removal mode start condition is met.

  According to a second aspect of the present invention, when the transfer material is not located at a contact portion between the latent image carrier and the transfer roller, a large amount of liquid carrier is transferred from the latent image carrier to the transfer roller. Foreign matter removal mode execution control means is provided for controlling the operation of the latent image carrier, the developing device, the transfer device, and the transfer roller cleaning member to execute the foreign matter removal mode. It is characterized by.

  Further, the invention according to claim 3 is that the forward bias having the same polarity as the polarity of the toner is applied between the transfer device and the developing device so as to contact the latent image carrier. A latent image carrier squeeze member for squeezing the developer image, and a reverse bias having a polarity opposite to the polarity of the toner is applied to the latent image carrier squeeze member when the foreign matter removal mode is executed. Yes.

  According to a fourth aspect of the present invention, there is provided a latent image carrier in which an electrostatic latent image is formed, and the electrostatic latent image is developed with a liquid developer comprising toner and a non-volatile liquid carrier. A developing device that forms a developer image thereon, a primary transfer device that primarily transfers the developer image on the latent image carrier to an intermediate transfer medium, and a secondary transfer roller that contacts the intermediate transfer medium during image formation. An image forming apparatus comprising at least a secondary transfer device for secondary transfer of a developer image on the intermediate transfer medium onto a transfer material being conveyed, wherein the secondary transfer device is disposed on the secondary transfer roller. A secondary transfer roller cleaning member that contacts and cleans the secondary transfer roller is provided, and the secondary transfer roller is attached to the secondary transfer roller in a larger amount than in a normal image forming operation, thereby allowing the secondary transfer roller to adhere to the secondary transfer roller. To Laura A foreign matter removal mode for removing foreign matter that adheres and foreign matter that adheres and accumulates on the secondary transfer roller cleaning member is set, and the foreign matter removal mode is executed when a foreign matter removal mode start condition is satisfied. Yes.

  Further, the invention according to claim 5 is that a large amount of liquid is transferred from the intermediate transfer medium to the secondary transfer roller when the transfer material is not located at a contact portion between the intermediate transfer medium and the secondary transfer roller. The foreign matter removal is performed by controlling the operation of the latent image carrier, the developing device, the primary transfer device, the intermediate transfer medium, the secondary transfer device, and the secondary transfer roller cleaning member so as to attach the carrier. A foreign substance removal mode execution control means for executing the mode is provided.

  Further, in the invention of claim 6, a forward bias having the same polarity as the polarity of the toner is applied between the primary transfer device and the developing device so as to abut on the latent image carrier. A latent image carrier squeezing member for squeezing the developer image on the upper side, and having the same polarity as the polarity of the toner between the primary transfer device and the secondary transfer device, in contact with the intermediate transfer medium And an intermediate transfer medium squeeze member that squeezes the developer image on the intermediate transfer medium when the forward bias is applied, and when the foreign matter removal mode is executed, the latent image carrier squeeze member and the intermediate transfer medium squeeze member Further, a reverse bias having a polarity opposite to that of the toner is applied to each of the toners.

  Furthermore, the invention according to claim 7 is a yellow, magenta, cyan, and black latent image carrier on which yellow, magenta, cyan, and black electrostatic latent images are respectively formed, and the yellow, magenta, cyan, and cyan. , And black electrostatic latent images are respectively developed with yellow, magenta, cyan, and black liquid developers composed of yellow, magenta, cyan, and black toners and a non-volatile liquid carrier. Yellow, magenta, cyan, and black developing devices for forming yellow, magenta, cyan, and black developer images on the latent image carriers of magenta, cyan, and black, and the yellow, magenta, The developer images on the cyan and black latent image carriers are respectively transferred to the intermediate transfer medium. Transfer materials that convey the developer image on the intermediate transfer medium by primary transfer devices of yellow, magenta, cyan, and black to be transferred next, and a secondary transfer roller that contacts the intermediate transfer medium during image formation At least a secondary transfer device for secondary transfer, and the latent image carriers are arranged in tandem in any order along the intermediate transfer medium, and are sequentially overlaid on the intermediate transfer medium for full color development. In the image forming apparatus in which the agent image is formed, the secondary transfer device includes a secondary transfer roller cleaning member that contacts the secondary transfer roller and cleans the secondary transfer roller, and the secondary transfer device By adhering a larger amount of the liquid carrier to the roller than during a normal image forming operation, the foreign matter adhering to the secondary transfer roller and the secondary transfer roller clamp With foreign substance removal mode has been set for removing each foreign matter adhering deposited Ningu member is characterized by executing the foreign substance removal mode when the foreign substance removal mode start condition is met.

  Further, the invention according to claim 8 is that a large amount of liquid is transferred from the intermediate transfer medium to the secondary transfer roller when the transfer material is not located at a contact portion between the intermediate transfer medium and the secondary transfer roller. The foreign matter removing mode is configured by controlling the operation of the latent image carrier, the developing device, the primary transfer device, the intermediate transfer medium, the secondary transfer device, and the secondary transfer roller cleaning member so as to attach a carrier. The image forming apparatus according to claim 7, further comprising a foreign matter removal mode execution control unit that executes the operation.

  Further, the invention according to claim 9 is provided between yellow, magenta, cyan, and black primary transfer devices and yellow, magenta, cyan, and black developing devices, respectively, yellow, magenta, cyan. And yellow, magenta, cyan, and black, which are in contact with each latent image carrier of black and apply a forward bias having the same polarity as that of the toner to squeeze the developer image on each latent image carrier. Each of the primary transfer devices of yellow, magenta, cyan, and black is provided with a black latent image carrier squeeze member, and the primary color of the first color located on the most upstream side in the rotation direction of the intermediate transfer medium. The intermediate transfer medium between the transfer device and the primary transfer device of the second color located next upstream in the rotational direction of the intermediate transfer medium A first intermediate transfer medium squeeze member that squeezes the developer image of the first color on the intermediate transfer medium by applying a forward bias of the same polarity as the polarity of the toner, and a primary of the second color A forward bias having the same polarity as the polarity of the toner is in contact with the intermediate transfer medium and between the transfer apparatus and the primary transfer apparatus of the third color positioned further upstream in the rotation direction of the intermediate transfer medium. A second intermediate transfer medium squeeze member that is applied to squeeze the second color developer image on the intermediate transfer medium, and further in the rotational direction of the third color primary transfer device and the intermediate transfer medium. A forward bias having the same polarity as the polarity of the toner is applied between the fourth color primary transfer device located on the upstream side and the third color on the intermediate transfer medium. Squeeze the developer image A forward bias having the same polarity as the polarity of the toner is in contact with the intermediate transfer medium and between the third intermediate transfer medium squeeze member and the primary transfer device of the fourth color and the secondary transfer roller. A fourth intermediate transfer medium squeeze member that is applied to squeeze the fourth color developer image on the intermediate transfer medium, and performs yellow, magenta, cyan, and black during execution of the foreign matter removal mode. A reverse bias having a polarity opposite to that of the toner is applied to at least one of the latent image carrier squeeze members and the first to fourth intermediate transfer medium squeeze members.

  According to the image forming apparatus of the present invention configured as described above, the foreign matter removal mode is executed when the foreign matter removal mode start condition is satisfied, and the entire circumference of the transfer roller is much more than that during the normal image forming operation. Since a large amount of liquid carrier is adhered and a large amount of liquid carrier adhering to the transfer roller is collected by the transfer roller cleaning member, the transfer material powder on the transfer roller that has floated due to a decrease in adhesion force due to the large amount of liquid carrier Foreign matter such as dust can be effectively scraped and removed by the transfer roller cleaning member, and foreign matter such as transfer material powder and dust that adheres and accumulates on the transfer roller cleaning member can be effectively washed away with a large amount of liquid carrier. Can be removed. In particular, since a non-volatile liquid carrier is used as the liquid carrier, a larger amount of the liquid carrier can be attached to the transfer roller, and the transfer roller and the transfer roller cleaning member by the liquid carrier are more effectively cleaned. be able to. As a result, the adhesion of the transfer roller cleaning member to the transfer roller can be maintained for a long time, so that the transfer roller and the transfer roller cleaning member can be effectively cleaned for a long time, and good image quality can be obtained for a long time. be able to.

  In addition, since the reverse bias having the reverse polarity to the toner is applied to each latent image carrier squeeze member and each intermediate transfer belt squeeze member when executing the foreign substance removal mode, the toner particles are applied to the liquid carrier attached to the intermediate transfer medium. The toner particles can be effectively removed by the photosensitive member squeeze members and the intermediate transfer belt squeeze member, and the removal of the liquid carrier can be suppressed. As a result, foreign substances on the transfer roller and the transfer roller cleaning member can be removed with a large amount of cleaner liquid carrier, and the cleaning effect thereof can be improved.

  Further, the non-volatile liquid carrier used in the developing device is used as a cleaning agent for removing foreign matters on the transfer roller and the transfer roller cleaning member, and these foreign matters are removed by the white solid image forming operation of the image forming apparatus. Therefore, a dedicated cleaning agent for cleaning and a dedicated cleaning device can be eliminated. Thereby, the structure of the image forming apparatus can be simplified and the cost can be reduced.

The best mode for carrying out the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram schematically and partially showing an example of an embodiment of an image forming apparatus according to the present invention.
As shown in FIG. 1, the image forming apparatus 1 of this example includes photoreceptors 2Y, 2M, 2C, and 2K composed of photoreceptor drums of yellow Y, magenta M, cyan C, and black K as latent image carriers. ing. Here, in the photoconductors 2Y, 2M, 2C, and 2K, 2Y represents a yellow photoconductor, 2M represents a magenta photoconductor, 2C represents a cyan photoconductor, 2K represents a black photoconductor, and the same applies to other members. It is.

  These photoconductors 2Y, 2M, 2C, and 2K are configured to rotate clockwise as indicated by arrows during operation. Around each of the photoreceptors 2Y, 2M, 2C, and 2K, charging devices 3Y, 3M, 3C, and 3K, exposure devices 4Y, 4M, 4C, and 4K, and developing devices 5Y, 5M, and so on are sequentially arranged from the upstream side in the rotation direction. 5C, 5K, photoconductor squeeze devices 6Y, 6M, 6C, 6K, primary transfer devices 7Y, 7M, 7C, 7K, static eliminators 8Y, 8M, 8C, 8K, and photoconductor cleaning devices 9Y, 9M, 9C, 9K It is arranged.

  Further, the image forming apparatus 1 includes an endless intermediate transfer belt 10 that is an intermediate transfer medium. The intermediate transfer belt 10 is stretched around a pair of drive rollers 11 and driven rollers 12 that are spaced apart from each other, and is provided to be able to rotate counterclockwise in FIG. 1, and each of the photoreceptors 2Y, 2M. , 2C, 2K are in contact with the primary transfer devices 7Y, 7M, 7C, 7K, respectively. The intermediate transfer belt 10 includes a base material layer made of polyimide (eg, thickness of 100 μm), an elastic layer made of urethane rubber (hardness JIS-A 30 °) (eg, thickness of 200 μm), and a coating layer made of fluororesin (eg, The image is formed on the coat layer by primary transfer.

  The photoreceptors 2Y, 2M, 2C, and 2K and the developing devices 5Y, 5M, 5C, and 5K are arranged in tandem along the intermediate transfer belt 10 from the upstream side in the rotation direction of the intermediate transfer belt 10 in this order. . However, the present invention is not limited to this, and the arrangement order of the photoconductors 2Y, 2M, 2C, and 2K and the developing devices 5Y, 5M, 5C, and 5K can be arbitrarily set.

  In the vicinity of the primary transfer devices 7Y, 7M, 7C, and 7K on the downstream side in the rotation direction of the intermediate transfer belt 10 from the primary transfer devices 7Y, 7M, 7C, and 7K, intermediate transfer belt squeeze devices 13Y, 13M, and 13C, respectively. , 13K are arranged. Further, a secondary transfer device 14 is provided on the drive roller 11 side of the intermediate transfer belt 10, and an intermediate transfer belt cleaning device 15 is provided on the driven roller 12 side of the intermediate transfer belt 10.

Further, the image forming apparatus 1 includes a transfer material storage device 17 including a transfer material storage cassette for storing, for example, paper 16 as a transfer material, and a registration roller pair 18 on the downstream side in the transfer material transport direction from the transfer material storage device 17. It has. Further, a liquid application device 19 is disposed in a transfer material conveyance path 52 a between the registration roller pair 18 and the secondary transfer device 14.
Although not shown, the image forming apparatus 1 of this example includes a fixing device and a paper discharge tray on the downstream side in the transfer material conveyance direction from the secondary transfer device 14 as in the conventional general image forming apparatus.

  Each of the charging devices 3Y, 3M, 3C, 3K is applied with a bias (forward bias) having the same polarity as the charging polarity of the toner particles of the liquid developer from a power supply device (not shown) during normal image forming operation. 2Y, 2M, 2C, and 2K are charged. In addition, each of the exposure devices 4Y, 4M, 4C, and 4K forms a latent image by irradiating the corresponding charged photoconductors 2Y, 2M, 2C, and 2K with, for example, laser light from a laser scanning optical system or the like. It is supposed to be.

  Each of the developing devices 5Y, 5M, 5C, and 5K includes developer supply units 20Y, 20M, 20C, and 20K, developing rollers 21Y, 21M, 21C, and 21K, and developing roller chargers 22Y, 22M, 22C, and 22K, respectively. The developing roller cleaners 23Y, 23M, 23C, and 23K and the developing roller cleaner recovery liquid storage units 24Y, 24M, 24C, and 24K are configured.

  The developer supply units 20Y, 20M, 20C, and 20K respectively include developer containers 26Y, 26M, and 26C that store liquid developers 25Y, 25M, 25C, and 25K including toner particles and a nonvolatile liquid carrier. , 26K, leveling rollers 27Y, 27M, 27C, 27K, developer supply rollers 28Y, 28M, 28C, 28K, and developer regulating blades 29Y, 29M, 29C, 29K.

  In the liquid developers 25Y, 25M, 25C, and 25K accommodated in the developer containers 26Y, 26M, 26C, and 26K, as the toner, a known pigment or the like is similarly incorporated into a known thermoplastic resin used for the toner. For example, particles having an average particle diameter of 1 μm in which a colorant is dispersed can be used. In the case of a low-viscosity and low-concentration liquid developer, for example, Isopar (trademark: Exxon) An insulating liquid carrier can be used. In the case of a liquid developer having a high viscosity and high concentration, for example, a silicone having a flash point of 210 ° C. or higher such as an organic solvent, phenylmethylsiloxane, dimethylpolysiloxane and polydimethylcyclosiloxane. Oils, mineral oils, aliphatics such as liquid paraffin with a boiling point of 130 ° C or higher and a relatively low viscosity of 3mPa · s at 40 ° C Sum hydrocarbons, normal paraffin, vegetable oils, can be used edible oil, higher fatty acid ester, an insulating liquid carrier and the like. The liquid developers 25Y, 25M, 25C, and 25K are obtained by adding toner particles to a liquid carrier together with a dispersant so that the toner solid content concentration is about 20%.

  The leveling rollers 27Y, 27M, 27C, 27K respectively have a function of pumping the liquid developers 25Y, 25M, 25C, 25K to the developer supply rollers 28Y, 28M, 28C, 28K and developer containers 26Y, 26M, 26C, This roller has a function of stirring in order to maintain the developer in 27K in an appropriate state. Further, the developer supply rollers 28Y, 28M, 28C, and 28K are all anilox rollers that are formed of a cylindrical member and have fine and uniform spiral grooves formed on the surface thereof. The dimensions of the groove are, for example, a groove pitch of about 130 μm and a groove depth of about 30 μm. The leveling rollers 27Y, 27M, 27C, and 27K and the developer supply rollers 28Y, 28M, 28C, and 28K are all rotated clockwise as indicated by arrows in FIG.

  Each of the developer regulating blades 29Y, 29M, 29C, and 29K includes a rubber portion made of urethane rubber or the like that contacts the surface of the developer supply rollers 28Y, 28M, 28C, and 28K, and a metal plate that supports the rubber portion. The liquid developer remaining on the developer supply rollers 28Y, 28M, 28C, and 28K is scraped off and removed.

Each of the developing rollers 21Y, 21M, 21C, and 21K is a cylindrical member having a width of, for example, about 320 mm. For example, an elastic body such as conductive urethane rubber and a resin are disposed on the outer peripheral portion of a metal core such as iron. A layer or a rubber layer is provided. These developing rollers 21Y, 21M, 21C, and 21K are configured to rotate counterclockwise as indicated by arrows in FIG.
Each of the developing roller chargers 22Y, 22M, 22C, and 22K includes, for example, a compression corona charger, and the like, and the corresponding developing rollers 21Y, 21M, 21C, and 21K are used as liquid developers during normal image forming operations. The toner particles are charged with a bias (forward bias) having the same polarity as the charging polarity of the toner particles. By the charging by the developing roller chargers 22Y, 22M, 22C, and 22K, the liquid developers 25Y, 25M, 25C, and 25K on the developing rollers 21Y, 21M, 21C, and 21K are respectively transferred to the developing rollers 21Y, 21M, 21C, and 21K. Pressed.

  Further, each of the developing roller cleaners 23Y, 23M, 23C, and 23K is made of, for example, rubber or the like that contacts the surface of the corresponding developing roller 21Y, 21M, 21C, or 21K, and is connected to the developing rollers 21Y, 21M, 21C, and 21K. The residual developer is scraped off and removed. Further, the developing roller cleaner collection liquid storage units 24Y, 24M, 24C, and 24K store the developer scraped off from the developing rollers 21Y, 21M, 21C, and 21K by the developing roller cleaners 23Y, 23M, 23C, and 23K, respectively. It is a container such as a tank.

  As shown in FIG. 2, the image forming apparatus 1 of this example further includes developer replenishers 30Y, 30M, and 30K that replenish liquid developers 25Y, 25M, 25C, and 25K to developer containers 26Y, 26M, 26C, and 26K, respectively. 30C, 30K. The developer replenishing devices 30Y, 30M, 30C, 30K are respectively provided with liquid developer tanks 31Y, 31M, 31C, 31K, liquid developer replenishing paths 32Y, 32M, 32C, 32K, and liquid developer replenishing pumps 33Y, 33M, 33C, 33K, liquid carrier tanks 34Y, 34M, 34C, 34K, liquid carrier supply paths 35Y, 35M, 35C, 35K, and liquid carrier supply pumps 36Y, 36M, 36C, 36K.

  The liquid developer supply paths 32Y, 32M, 32C, and 32K and the liquid developer supply pumps 33Y, 33M, 33C, and 33K are connected to the developer containers 26Y, 26M, 26C, and 26K. Then, a liquid developer amount detection sensor (not shown) provided in each of the developer containers 26Y, 26M, 26C, and 26K that detects the liquid developer amount detects that the liquid developer amount has become a predetermined value or less. At this time, the liquid developer supply pumps 33Y, 33M, 33C, and 33K corresponding to the detected liquid developer are driven, and the liquid developer is supplied through the liquid developer supply paths 32Y, 32M, 32C, and 32K by a set amount. The developer containers 26Y, 26M, 26C and 26K are replenished. When a liquid carrier amount detection sensor (not shown) provided in each of the developer containers 26Y, 26M, 26C, and 26K detects the liquid carrier amount, it is detected that the liquid carrier amount has become a predetermined value or less. The liquid carrier supply pumps 36Y, 36M, 36C, 36K corresponding to the detected liquid carrier are driven, and the liquid carriers are supplied to the developer containers 26Y, 26M, 26K via the set amount liquid carrier supply paths 35Y, 35M, 35C, 35K. 26C and 26K are replenished.

  As shown in FIG. 1, the photoconductor squeeze devices 6Y, 6M, 6C, and 6K include photoconductor squeeze rollers 37Y, 37M, 37C, and 37K that are latent image carrier squeeze members of the present invention, and a squeeze roller cleaner 38Y, respectively. , 38M, 38C, 38K and squeeze roller cleaner recovery liquid storage containers 39Y, 39M, 39C, 39K. The photosensitive member squeeze rollers 37Y, 37M, 37C, and 37K are respectively connected to the developing rollers 21Y, 21M from contact portions (nip portions) of the photosensitive members 2Y, 2M, 2C, and 2K and the developing rollers 21Y, 21M, 21C, and 21K. , 21C, 21K downstream of the rotating direction of the photoconductors 2Y, 2M, 2C, 2K so that they can be pressed and separated from each other and rotated in the opposite direction to the photoconductors 2Y, 2M, 2C, 2K. The liquid carrier on the bodies 2Y, 2M, 2C, 2K is removed. A squeeze bias (forward bias) of +300 V to +500 V having the same polarity as the toner particles of the liquid developer is applied to each of the photoconductor squeeze rollers 37Y, 37M, 37C, and 37K during a normal image forming operation.

  As each of the photoreceptor squeeze rollers 37Y, 37M, 37C, and 37K, an elastic roller in which an elastic member such as conductive urethane rubber and a fluororesin surface layer are arranged on the surface of a metal core is suitable. Each of the squeeze roller cleaners 38Y, 38M, 38C, and 38K is made of an elastic material such as rubber, and is provided so as to be detachable from the corresponding photosensitive member squeeze rollers 37Y, 37M, 37C, and 37K. In contact with the surfaces of the corresponding photosensitive member squeeze rollers 37Y, 37M, 37C, and 37K at the time of image forming operation, the liquid carriers remaining on these photosensitive member squeeze rollers 37Y, 37M, 37C, and 37K are scraped off and removed. It is. Furthermore, each squeeze roller cleaner recovery liquid storage container 39Y, 39M, 39C, 39K is a container such as a tank for storing the developer scraped off by the corresponding squeeze roller cleaner 38Y, 38M, 38C, 38K.

  Each of the primary transfer devices 7Y, 7M, 7C, and 7K includes primary transfer backup rollers 40Y, 40M, 40C, and 40K that bring the intermediate transfer belt 10 into contact with the photoreceptors 2Y, 2M, 2C, and 2K, respectively. Each of the backup rollers 40Y, 40M, 40C, and 40K is applied with, for example, about −200 V having a polarity opposite to the charging polarity of the toner particles, and the developer images on the photoreceptors 2Y, 2M, 2C, and 2K are transferred to the intermediate transfer belt 10. Primary transfer. Each of the static eliminators 8Y, 8M, 8C, and 8K removes the electric charge remaining on the photoreceptors 2Y, 2M, 2C, and 2K after the primary transfer.

  Each of the photoconductor cleaning devices 9Y, 9M, 9C, and 9K includes photoconductor cleaners 41Y, 41M, 41C, and 41K and photoconductor cleaner collection liquid storage containers 42Y, 42M, 42C, and 42K. Each of the photoconductor cleaners 41Y, 41M, 41C, and 41K is made of an elastic material such as rubber, and abuts against the surface of the corresponding photoconductors 2Y, 2M, 2C, and 2K, and contacts the photoconductors 2Y, 2M, 2C, and 2K. The remaining developer is scraped off and removed. The photoreceptor cleaner collection liquid storage containers 42Y, 42M, 42C, and 42K collect and store the developer scraped off from the photoreceptors 2Y, 2M, 2C, and 2K by the photoreceptor cleaners 41Y, 41M, 41C, and 41K, respectively. To do.

  Each of the intermediate transfer belt squeeze devices 13Y, 13M, 13C, and 13K is provided so as to be capable of being pressed against and separated from the intermediate transfer belt 10 and is an intermediate transfer medium squeeze roller pair 43Y, 43Y, which is the intermediate transfer medium squeeze member of the present invention. 43M, 43C, 43K, intermediate transfer belt squeeze roller cleaner 44Y, 44M, 44C, 44K, intermediate transfer belt squeeze roller cleaner recovery liquid storage container 39M, 39C, 39K, 45K (for squeeze for cyan, magenta, and cyan) Roller cleaner recovery liquid storage container 39M, 39C, 39K). The intermediate transfer belt squeeze roller pairs 43Y, 43M, 43C, 43K collect liquid carriers of corresponding colors on the intermediate transfer belt 10, respectively. Each intermediate transfer belt squeeze roller pair 43Y, 43M, 43C, 43K is also applied with a squeeze bias (forward bias) of + 300V to + 500V having the same polarity as the toner particles of the liquid developer during a normal image forming operation. The intermediate transfer belt squeeze roller cleaners 44Y, 44M, 44C, and 44K are detachably attached to the corresponding intermediate transfer belt squeeze roller pairs 43Y, 43M, 43C, and 43K, respectively. It contacts the squeeze roller pair 43Y, 43M, 43C, 43K and scrapes the collected liquid carrier on these rollers. Further, the intermediate transfer belt squeeze roller cleaner collection liquid storage containers 39M, 39C, 39K, and 45K collect and store the liquid carriers scraped by the intermediate transfer belt squeeze roller cleaners 44Y, 44M, 44C, and 44K, respectively.

  The secondary transfer device 14 includes a secondary transfer roller 46 that can be pressed against and separated from the intermediate transfer belt, a secondary transfer roller cleaner 47 that is a transfer roller cleaning member, and a secondary transfer roller cleaner recovery liquid storage container. 48. The secondary transfer roller 46 brings the paper 16 into contact with the intermediate transfer belt 10 hung on the driving roller 11, and transfers the color toner image in which the toner images of each color on the intermediate transfer belt 10 are combined onto the paper 16. To do. In that case, the drive roller 11 also functions as a backup roller during secondary transfer. Further, in the case of continuous transfer onto a plurality of sheets of paper 16, the secondary transfer roller 46 is always in contact with the intermediate transfer belt 10 during this continuous transfer. The secondary transfer roller cleaner 47 is configured as, for example, a cleaning blade made of an elastic body such as rubber, and is provided so as to be able to come into contact with the secondary transfer roller 46. After the secondary transfer, the secondary transfer roller cleaner 47 comes into contact with the secondary transfer roller 46. The liquid developer remaining on the surface of the secondary transfer roller 46 is scraped off and removed. The secondary transfer roller cleaner recovery liquid storage container 48 collects and stores the developer scraped off from the secondary transfer roller 46 by the secondary transfer roller cleaner 47.

  The intermediate transfer belt cleaning device 15 is provided so as to be capable of being pressed against the intermediate transfer belt 10, and includes an intermediate transfer belt cleaner 49 composed of, for example, a cleaning blade and an intermediate transfer belt cleaner recovery liquid storage container 50. The intermediate transfer belt cleaner 49 is made of an elastic material such as rubber, and is in contact with the intermediate transfer belt 10 to scrape and remove the developer remaining on the surface of the intermediate transfer belt 10 after the secondary transfer. In that case, the driven roller 12 also functions as a backup roller at the time of cleaning the intermediate transfer belt. The intermediate transfer belt cleaner recovery liquid storage container 50 collects and stores the developer scraped off from the intermediate transfer belt 10 by the intermediate transfer belt cleaner 49.

  The transfer material storage device 17 has a pickup roller 51 as in the conventional general image forming apparatus. The pickup roller 51 picks up the paper 16 in the transfer material storage device 17 one by one and feeds it to the registration roller pair 18 via the transfer material conveyance path 52. The registration roller pair 18 corrects the skew of the paper 16 and the feeding timing, and feeds the paper 16 toward the liquid coating device 19.

  The liquid application device 19 includes a sponge roller 53 that is rotatable and press-separable from the conveyed paper 16, a backup roller 55 that presses the paper 16 between the sponge roller 53, and the paper 16. And an application liquid storage container 59 for storing the application liquid 58 to be applied.

  The squeeze roller cleaner recovery liquid storage container 39Y and the intermediate transfer belt cleaner recovery liquid storage container 50 are connected to the common recovery path 61 via the recovery path 60, and the squeeze roller cleaner recovery liquid storage container 39M and the photoreceptor cleaner recovery liquid storage. The container 42Y is connected to the common recovery path 61 via the recovery path 62, and the squeeze roller cleaner recovery liquid storage container 39C and the photoreceptor cleaner recovery liquid storage container 42M are connected to the common recovery path 61 via the recovery path 63. Further, the squeeze roller cleaner recovery liquid storage container 39K and the photoreceptor cleaner recovery liquid storage container 42C are connected to the common recovery path 61 via the recovery path 64, and further, the photoreceptor cleaner recovery liquid storage container 42K and the intermediate transfer belt squeeze. Roller cleaner recovery liquid storage container 45K It is connected to a common collection passage 61 through the yield passage 65. The common recovery passage 61 is connected to a recovery carrier storage container 68 via a recovery pump 66 and a filter 67. Further, the secondary transfer roller cleaner recovery liquid storage container 48 is connected to a recovery carrier storage container 68 via a recovery passageway 69, a recovery pump 66 and a filter 67.

  Accordingly, the squeeze roller cleaner recovery liquid storage containers 39Y, 39M, 39C, 39K, the photoreceptor cleaner recovery liquid storage containers 42Y, 42M, 42C, 42K, the intermediate transfer belt squeeze roller cleaner recovery liquid storage container 45K, and the intermediate transfer belt cleaner recovery. The developer collected in the liquid storage container 50 is sucked by the collection pump 66 and impurities such as toner particles are removed by the filter 67 so that the developer is stored in the recovery carrier storage container 68 as a pure liquid carrier. It has become.

  Further, the collection carrier storage container 68 is connected to the common return passage 70. The common reduction passage 70 is connected to the developer containers 26Y, 26M, 26C, and 26K via the reduction passages 71Y, 71M, 71C, and 71K and the reduction pumps 72Y, 72M, 72C, and 72K, respectively. It is connected to the coating liquid storage container 59 via a reduction passage 73 and a reduction pump 74. Therefore, the recovery liquid carrier in the recovery carrier storage container 68 is driven by the reduction pumps 72Y, 72M, 72C, 72K, 74, respectively, so that the developer containers 26Y, 26M, 26C, 26K and the coating liquid storage container 59 are driven. Each is supplied and reduced.

  In the image forming apparatus 1 of this example configured as described above, when the image forming operation is started, first, in the yellow Y developing device 5Y, the yellow Y liquid developer 25Y is developed by the leveling roller 27Y. While being pumped up by the supply roller 28Y, an appropriate amount is attached to the developer supply roller 28Y by the developer regulating blade 29Y. The liquid developer 25Y on the developer supply roller 28Y is supplied to the developing roller 21Y and is conveyed toward the photoreceptor 2Y by the developing roller 21Y.

  The electrostatic latent image formed on the yellow Y photoreceptor 2Y is developed with the yellow Y liquid developer 25Y in the developing device 5Y, and a yellow Y liquid developer image is formed on the photoreceptor 2Y. The developer remaining on the developing roller 21Y after development is removed from the developing roller 21Y by the developing roller cleaner 23Y. The yellow Y liquid developer image on the photoreceptor 2Y is collected as a yellow Y toner image by collecting the liquid carrier on the photoreceptor 2Y by the photoreceptor squeeze roller 37Y. The yellow Y toner image is the primary transfer device 7Y. Then, the image is transferred to the intermediate transfer belt 10. The yellow Y toner image on the intermediate transfer belt 10 is conveyed toward the primary transfer device 7M of magenta M while the liquid carrier on the intermediate transfer belt 10 is collected by the pair of intermediate transfer belt squeeze rollers 43Y.

  Next, the electrostatic latent image formed on the photoconductor 2M of magenta M is developed in the developing device 5M with the magenta M liquid developer conveyed in the same manner as in the case of yellow Y, and the magenta M is developed on the photoconductor 2M. The liquid developer image is formed. The developer remaining on the developing roller 21M after development is removed from the developing roller 21M by the developing roller cleaner 23M. The liquid developer image of magenta M on the photoreceptor 2M is recovered as a magenta M toner image by collecting the liquid carrier on the photoreceptor 2M by the photoreceptor squeeze roller 37M. The toner image of magenta M is the primary transfer device 7M. Thus, the yellow Y toner image is superimposed on the intermediate transfer belt 10 and transferred. Similarly, the color-superposed yellow Y and magenta M toner images are conveyed toward the cyan C primary transfer device 7C while the liquid carrier on the intermediate transfer belt 10 is collected by the intermediate transfer belt squeeze roller pair 43M. The In the same manner, a cyan toner image and a black toner image are sequentially superimposed and transferred onto the intermediate transfer belt 10 to form a full-color toner image on the intermediate transfer belt 10.

  On the other hand, the sheet 16 picked up from the transfer material storage device 17 is fed to the liquid coating device 19 with the feeding timing adjusted by the registration roller pair 18. The liquid coating device 19 feeds the paper 16 toward the secondary transfer device 14 while applying the coating liquid 58 to the transfer surface side of the fed paper 16. At this time, the paper 16 has an appropriate rigidity by being coated with the coating liquid 58 and is deformed into a shape suitable for secondary transfer by the intermediate transfer belt 10 and the secondary transfer roller 46.

  Next, the secondary transfer device 14 transfers the color toner image on the intermediate transfer belt 10 onto the transfer surface of the paper 16 that has been supplied with the coating liquid and fed. At this time, since the paper 16 is deformed into a shape suitable for the secondary transfer, the secondary transfer is favorably performed. The developer remaining on the intermediate transfer belt 10 after the completion of the secondary transfer is removed from the intermediate transfer belt 10 by the intermediate transfer belt cleaning device 15, and the developer remaining on the secondary transfer roller 46 is The secondary transfer roller 46 is removed by the secondary transfer roller cleaner 47. Finally, the color toner image transferred onto the paper 16 is fixed by a fixing device (not shown) as in the prior art, and the paper 16 on which the full-color fixed image is formed is conveyed to a paper discharge tray to form a color image. The operation ends.

  By the way, if foreign matter such as paper dust, toner particles, and dust in the apparatus adheres to the secondary transfer roller 46 as described above, the foreign matter on the secondary transfer roller 46 becomes secondary after a long time has passed. It adheres to and accumulates on the transfer roller cleaner 47.

  Accordingly, in the image forming apparatus 1 of this example, foreign matters such as paper dust and dust adhering to the secondary transfer roller 46 and foreign matters such as paper dust and dust accumulated on the secondary transfer roller cleaner 47 are periodically removed. In addition, the foreign matter removal mode is set, and the foreign matter removal mode execution control means for executing the foreign matter removal mode is provided in the controller for controlling the operation of the image forming apparatus 1.

FIGS. 3A and 3B illustrate the execution of the foreign substance removal mode, where FIG. 3A is a diagram illustrating a state before the liquid carrier of the white solid image is applied to the secondary transfer roller, and FIG. 3B is the secondary of the liquid carrier of the white solid image. It is a figure which shows the state in the process of application | coating to a transfer roller.
In the image forming apparatus 1 of this example, white images are formed on the photoreceptors 2Y, 2M, 2C, and 2K when the foreign substance removal mode is executed, and as shown in FIG. 3A, these latent image carriers are formed. The solid white image is transferred to the intermediate transfer belt 10. This solid white image is a cleaning image for removing foreign matters from the secondary transfer roller 46 and the secondary transfer roller cleaner 47.

  The length of the solid image in the conveyance direction (the length between the front end A and the rear end B) S is longer than the peripheral length (πD) of the outer periphery of the secondary transfer roller 46 having a diameter D (S> πD). ) Is set. For example, assuming that the diameter D of the secondary transfer roller 46 is 35 mm, the length S of the solid white image is set to 110 mm. As shown in FIG. 3B, a white image on the intermediate transfer belt 10 is formed on the outer peripheral surface of the secondary transfer roller 46 at a contact portion (nip portion) between the intermediate transfer belt 10 and the secondary transfer roller 46. It comes to adhere.

  This foreign matter removal mode is a mode that is set when the foreign matter removal mode start condition is satisfied and performs cleaning of the secondary transfer roller 46 and the secondary transfer roller cleaner 47 by sequence control. The foreign matter removal mode start condition may be any condition as long as it is a condition related to a state in which foreign matter adheres to and accumulates on the secondary transfer roller 46 and the secondary transfer roller cleaner 47. When the foreign matter removal mode is executed, the foreign matter removal mode start condition that has been counted so far is reset, and counting of a new foreign matter removal mode start condition is started. Examples of the foreign matter removal mode start condition include jam detection, detection of the absence of paper in the transfer material storage device 17, or detection of an image forming operation for a preset number of sheets (for example, 100 sheets). In the following description, it is assumed that the foreign matter removal mode is executed using jam detection as the foreign matter removal mode start condition.

FIG. 4 is a diagram showing a flow for setting and executing the foreign substance removal mode.
As shown in FIG. 4, it is determined whether the foreign matter removal mode start condition is satisfied in step S <b> 1 when the image forming apparatus 1 is operating or the image forming apparatus 1 is powered on. If it is determined in step S1 that the foreign matter removal mode start condition is not satisfied, the determination processing for establishing the foreign matter removal mode start condition in step S1 is repeatedly performed. If it is determined in step S1 that the foreign matter removal mode start condition is satisfied, the foreign matter removal mode is executed in step S2.

FIG. 5 is a diagram for explaining foreign matter removal mode execution control means for performing the foreign matter removal mode.
As shown in FIG. 5, a foreign matter removal mode execution control means 75 for performing the foreign matter removal mode is provided in the controller 76 for controlling the operation of the image forming apparatus 1. The foreign matter removal mode execution control means 75 includes photoreceptors 2Y, 2M, 2C, 2K, charging devices 3Y, 3M, 3C, 3K, exposure devices 4Y, 4M, 4C, 4K, developing devices 5Y, 5M, 5C, 5K. Photoconductor squeeze devices 6Y, 6M, 6C, 6K, primary transfer devices 7Y, 7M, 7C, 7K, drive roller 11 for intermediate transfer belt 10, intermediate transfer belt squeeze devices 13Y, 13M, 13C, 13K, secondary transfer device 14, a secondary transfer roller cleaner 47, and a jam detecting means 77 are connected to each other.

  When the foreign matter removal mode execution control means 75 determines that the foreign matter removal start condition based on the jam detection by the jam detection means 77 is satisfied, the photoreceptor 2Y, 2M, 2C, 2K, charging devices 3Y, 3M, 3C, 3K, exposure devices 4Y, 4M, 4C, 4K, developing devices 5Y, 5M, 5C, 5K, photoreceptor squeeze devices 6Y, 6M, 6C, 6K, primary transfer Drive units 7Y, 7M, 7C, and 7K, drive roller 11 of intermediate transfer belt 10, intermediate transfer belt squeeze devices 13Y, 13M, 13C, and 13K, and secondary transfer unit 14 and secondary transfer roller cleaner 47 are driven and separated. The foreign matter removal mode is executed by controlling the contact and bias settings, respectively.

  FIG. 6 is a diagram for explaining the timing of sequence control performed in the foreign substance removal mode. In FIG. 6, the alternate long and short dash line indicates the movement of a solid image that is a cleaning image for cleaning the secondary transfer roller 46 and the secondary transfer roller cleaner 47 in the foreign substance removal mode. In this case, A indicates the movement of the front edge of the white solid image. B indicates the movement of the trailing edge of the white solid image. The length of the time axis (horizontal axis to the right in FIG. 6) between the front end A and the rear end B of the white solid image is the white image forming time T.

  When the foreign matter removal mode execution control means 75 of the controller 76 determines that a jam has occurred in the image forming apparatus 1 based on the jam detection signal from the jam detection means 77, the preparation for execution of the foreign matter removal mode is started. When the jam is resolved and the image forming apparatus 1 is reset automatically or manually, the foreign matter removal mode execution control means 75 determines that the foreign matter removal mode start condition is satisfied and executes the foreign matter removal mode.

  First, each charging device 3Y, 3M, 3C, 3K, each developing roller charger 22Y, 22M, 22C, 22K, each developing device 5Y, 5M, 5C, 5K developing roller 21Y, 21M, 21C, 21K, each photoconductor Squeeze rollers 37Y, 37M, 37C, 37K, primary transfer devices 7Y, 7M, 7C, 7K, primary transfer rollers 40Y, 40M, 40C, 40K, intermediate transfer belt squeeze roller pairs 43Y, 43M, 43C, 43K, and two A forward bias is applied to each secondary transfer roller 46 of the next transfer device 14.

  Further, since each exposure device 4Y, 4M, 4C, 4K is not operated, each of the photoreceptors 2Y, 2M, 2C, 2K has a normal electrostatic latent image by exposure of each exposure device 4Y, 4M, 4C, 4K, respectively. Is not formed. Accordingly, a solid white image (white solid print) of only the liquid carrier is formed on each of the photoconductors 2Y, 2M, 2C, and 2K. On the other hand, the liquid developers pressed against the developing rollers 21Y, 21M, 21C, and 21K by the developing roller chargers 22Y, 22M, 22C, and 22K are respectively applied to the photosensitive members 2Y, 2M by the developing rollers 21Y, 21M, 21C, and 21K. , 2C, 2K. Then, almost only the liquid carrier is attached to the solid image forming areas of the photosensitive members 2Y, 2M, 2C, and 2K from the developing rollers 21Y, 21M, 21C, and 21K at the respective development positions. The liquid carriers on these photoreceptors 2Y, 2M, 2C, and 2K are squeezed by the photoreceptor squeeze rollers 37Y, 37M, 37C, and 37K to which forward bias is applied, respectively, and most of the liquid carriers are removed. .

A reverse bias having a polarity opposite to that of the toner is applied to the yellow Y photoconductor squeeze roller 37Y with a time difference (time delay) based on the same speed as the peripheral speed V of the photoconductor 2Y from the time point when the forward bias is applied. In that case, the peripheral speeds of the photosensitive members 2Y, 2M, 2C, and 2K and the conveyance speed V of the paper 16 are set to be equal. The reverse bias is applied to the photoconductor squeeze roller 37Y only for a time T, and then the same forward bias is applied to the photoconductor squeeze roller 37Y again. This time T is the above-described white solid image forming time T, and the length S of the white solid image (cleaning image) formed on the intermediate transfer belt 10 shown in FIG. 3 is divided by the peripheral speed V of the photoreceptor 2Y. (T = S / V).
When a reverse bias is applied to the photosensitive member squeeze roller 37Y, the liquid carrier on the photosensitive member 2Y is effectively removed by the photosensitive member squeeze roller 37Y, but the liquid carrier itself is almost removed. Instead, it is made into a large amount of cleaner liquid carrier and conveyed toward the primary transfer device 7Y.

  The liquid carrier in the solid image forming area on the photoreceptor 2Y conveyed to the primary transfer device 7Y is primarily transferred to the intermediate transfer belt 10 by the primary transfer device 7Y. Further, a large amount of the liquid carrier on the intermediate transfer belt 10 is conveyed toward the primary transfer device 7M of magenta M. In that case, the intermediate transfer belt squeeze has a predetermined time difference from the application time of the reverse bias to the photoreceptor squeeze roller 37Y before a large amount of liquid carrier on the intermediate transfer belt 10 reaches the intermediate transfer belt squeeze device 13Y. A reverse bias of the same magnitude is applied to the intermediate transfer belt squeeze roller pair 43Y of the apparatus 13Y. The reverse bias is applied to the intermediate transfer belt squeeze roller pair 43Y for the same time T as described above, and then the same forward bias is applied to the intermediate transfer belt squeeze roller pair 43Y again. A large amount of the liquid carrier on the intermediate transfer belt 10 is more effectively removed by the pair of intermediate transfer belt squeeze rollers 43Y to which the reverse bias is applied, but the liquid carrier itself is almost removed. Instead, it is made into a large amount of a more clean liquid carrier and conveyed toward the primary transfer device 7M.

Further, as in the case of the yellow Y described above, a white image is formed on the photoconductor 2M of magenta M, and almost only the liquid carrier is attached to the white image forming area of the photoconductor 2M from the developing roller 21M. The On the other hand, the reverse bias of the same magnitude is applied to the photoconductor squeeze roller 37M of magenta M with the aforementioned predetermined time difference from the application time point of the reverse bias to the intermediate transfer belt squeeze roller pair 43Y. The reverse bias is applied to the photoconductor squeeze roller 37Y only for a time T, and then the same forward bias is applied to the photoconductor squeeze roller 37Y again.
When a reverse bias is applied to the photoconductor squeeze roller 37M, the liquid carrier on the photoconductor 2M is effectively removed by the photoconductor squeeze roller 37M, but the liquid carrier itself is almost removed. Instead, a large amount of clean liquid carrier is conveyed to the primary transfer device 7M.

  The liquid carrier in the solid image forming area on the photoreceptor 2M conveyed to the primary transfer device 7M is primarily transferred to the intermediate transfer belt 10 by the primary transfer device 7M. In that case, the liquid carrier on the photoreceptor 2M is superposed on the liquid carrier on the intermediate transfer belt 10 conveyed from the primary transfer device 7Y, so that a larger amount is obtained. Further, a large amount of liquid carrier on the intermediate transfer belt 10 is conveyed toward the primary transfer device 7C of cyan C. In this case, as in the case of the above-described yellow Y, a large amount of liquid carrier on the intermediate transfer belt 10 reaches the intermediate transfer belt squeeze device 13M before the application of the reverse bias to the photosensitive member squeeze roller 37M. The reverse bias of the same magnitude is applied to the intermediate transfer belt squeeze roller pair 43M of the intermediate transfer belt squeeze device 13M with a predetermined time difference. The reverse bias is applied to the intermediate transfer belt squeeze roller pair 43M for the same time T as described above, and then the same forward bias is applied to the intermediate transfer belt squeeze roller pair 43M again. A large amount of the liquid carrier on the intermediate transfer belt 10 is more effectively removed by the pair of intermediate transfer belt squeeze rollers 43M to which the reverse bias is applied, but the liquid carrier itself is almost removed. Rather, it is made into a larger amount of a more clean liquid carrier and conveyed toward the primary transfer device 7C.

  Thereafter, in the case of cyan C and black K, similarly to the above, the photosensitive member squeeze roller 37C, the belt squeeze roller pair 43C, the photosensitive member squeeze roller 37K, and the belt squeeze roller pair 43K are sequentially timed with the predetermined time difference described above. As shown in FIG. 3 (a), a reverse bias is applied, and the four photoreceptors 2Y, 2M, 2C, and 2K are sequentially superimposed and transferred onto the intermediate transfer belt 10 as shown in FIG. A white solid image having a length S is formed. The white solid image on the intermediate transfer belt 10 is conveyed toward the secondary transfer device 14.

  In the secondary transfer device 14, a large amount of liquid carrier subsequently conveyed by the intermediate transfer belt 10 adheres to the secondary transfer roller 46 that contacts the intermediate transfer belt 10. When the liquid carrier adhering to the secondary transfer roller 46 is conveyed to the secondary transfer roller cleaner 47, it is removed by the secondary transfer roller cleaner 47 and stored in the secondary transfer roller cleaner recovery liquid storage container 48. The At this time, foreign matters such as paper dust, residual toner and dust adhering to the secondary transfer roller 46 and similar foreign matters adhering to the secondary transfer roller cleaner 47 are weakened by the liquid carrier. It is removed along with the liquid carrier.

  Since the length S of the solid white image is set to be longer than the peripheral length (πD) of the secondary transfer roller 46, a large amount of liquid carrier is attached to the entire circumference of the secondary transfer roller 46, The adhering foreign matter is removed, and when the liquid carrier adhering to the secondary transfer roller 46 is removed by the secondary transfer roller cleaner 47 over the entire circumference of the secondary transfer roller 46, the foreign matter removal mode ends. Thus, the secondary transfer roller 46 and the secondary transfer roller cleaner 47 are cleaned by executing the foreign matter removal mode.

  According to the image forming apparatus 1 of this example, when the jam is resolved and the foreign matter removal mode start condition is satisfied, a large amount of liquid carrier is applied over the entire circumference of the secondary transfer roller 46 as compared with the normal image forming operation. Since a large amount of liquid carrier is attached and a large amount of liquid carrier adhering to the secondary transfer roller 46 is collected by the secondary transfer roller cleaner 47, the adhering force is lowered by the large amount of liquid carrier, and the secondary is lifted. Foreign matter such as paper dust and dust on the transfer roller 46 can be effectively scraped and removed by the secondary transfer roller cleaner 47, and foreign matter such as paper dust and dust that adheres to and accumulates on the secondary transfer roller cleaner 47. Can be effectively washed away with a large amount of liquid carrier. In particular, since a non-volatile liquid carrier is used as the liquid carrier, a larger amount of the liquid carrier can be attached to the secondary transfer roller 46, and the secondary transfer roller 46 and the secondary transfer roller cleaner by the liquid carrier are used. 47 can be cleaned more effectively. As a result, the adhesion of the secondary transfer roller cleaner 47 to the secondary transfer roller 46 can be maintained for a long time, so that the secondary transfer roller 46 and the secondary transfer roller cleaner 47 are effectively cleaned for a long time. And good image quality can be obtained over a long period of time.

  Further, when the foreign substance removal mode is executed, a reverse bias having a polarity opposite to that of the toner is applied to each of the photosensitive member squeeze rollers 37Y, 37M, 37C, and 37K and the intermediate transfer belt squeeze roller pair 43Y, 43M, 43C, and 43K. Even if the toner particles are contained in the liquid carrier adhering to the intermediate transfer belt 10, the toner particles are effectively removed by the photosensitive member squeeze rollers 37Y, 37M, 37C, and 37K and the intermediate transfer belt squeeze roller pair 43K. And the removal of the liquid carrier can be suppressed. As a result, foreign substances on the secondary transfer roller 46 and the secondary transfer roller cleaner 47 can be removed with a large amount of cleaner liquid carrier, and the cleaning effect can be further improved.

  Further, the liquid carrier used in the developing devices 5Y, 5M, 5C, and 5K is used as a cleaning agent for removing foreign matters in the secondary transfer roller 46 and the secondary transfer roller cleaner 47, and the solid image of the image forming apparatus 1 is used. Since these foreign substances are removed by the forming operation, a dedicated cleaning agent for cleaning and a dedicated cleaning device can be dispensed with. Thereby, the structure of the image forming apparatus 1 can be simplified and the cost can be reduced.

  It should be noted that the liquid carrier that adheres before the front end A of the solid image that is the cleaning image on each of the photoconductors 2Y, 2M, 2C, and 2K has an unstable potential on each of the photoconductors 2Y, 2M, 2C, and 2K. Or the toner layers on the developing rollers 21Y, 21M, 21C, and 21K are unstablely compressed.

  An experiment was conducted in the foreign matter removal mode by adhering a larger amount of liquid carrier to the transfer roller than during normal image forming operation. The image forming apparatus of the experimental apparatus was produced specially for the experiment and was a monochrome image forming apparatus instead of the tandem type image forming apparatus shown in FIG. A known amorphous silicon photoreceptor is used as the photoreceptor, and the intermediate transfer belt has a three-layer elastic structure comprising a fluorine-coated surface layer having a thickness of about 10 μm, a polyurethane intermediate layer having a thickness of 200 μm, and a polyimide base layer having a thickness of 80 μm. An intermediate transfer belt was used. As the transfer roller, a roller having a urethane rubber surface coated with a fluororesin was used, and the diameter was set to 25 mm. The actual resistance of these transfer rollers was 104Ω. Liquid paraffin was used as the liquid carrier. A cleaning blade made of urethane rubber was used for the transfer roller cleaner. The transfer bias applied to the transfer roller is 1 kV, the transfer pressure of the transfer roller is 1.5 kg / cm, the contact pressure of the cleaning blade to the transfer roller is 0.2 kg / cm, the printing speed is 200 mm / sec, The experiment was conducted with the length S set to 80 mm. A bias of −300 V having a polarity opposite to that of the toner was applied to the photosensitive member squeeze roller and the intermediate transfer belt squeeze roller when the foreign matter removal mode was executed. The paper used was high-quality plain paper for color laser, and 10,000 test images mixed with line drawings and solid patches were continuously printed on this paper, and the foreign matter removal mode was executed for every 100 images formed. In the continuous printing of 10,000 sheets, the printing operation of the image forming apparatus 1 is temporarily interrupted by the replenishment of the paper 16 to the transfer material storage device 17, but another image printing operation is performed in the middle. Needless to say, the same printing operation is performed substantially continuously on a total of 10,000 sheets.

  As a result of the experiment, when the foreign matter removal mode was not executed, paper dust accumulated on the transfer roller cleaner after about 2,000 sheets, causing uneven transfer, and the granularity of the output image deteriorated. Also, irregularly large paper dust was transferred to the printed image, especially when this large paper dust was transferred to the dark part of the image, which was recognized as an image smudge. Further, when the foreign matter removal mode was executed for every 100 sheets of image formation, no deterioration in toner granularity or image smear due to paper dust was observed even after printing 10,000 sheets. As a result, it can be confirmed that the cleaning of the transfer roller can be performed for a long time by attaching a larger amount of liquid carrier to the transfer roller than in the normal image forming operation in the foreign matter removal mode as in the present invention. It was.

  In the image forming apparatus of the above-described example, reverse bias is applied to all the photosensitive member squeeze rollers 37Y, 37M, 37C, and 37K and all the intermediate transfer belt squeeze roller pairs 43Y, 43M, 43C, and 43K when the foreign substance removal mode is executed. The removal of the liquid carrier is suppressed by applying the squeeze of the liquid carrier, but depending on the situation such as how the secondary transfer roller 46 is soiled, these photoreceptor squeeze rollers 37Y, 37M, 37C, 37K and intermediate transfer A reverse bias may be applied to at least one of the belt squeeze roller pairs 43Y, 43M, 43C, and 43K. In that case, the liquid carrier can be supplied to the secondary transfer roller 46 from the developing device of the color having the largest storage amount of the liquid carrier. At this time, a reverse bias is applied to the squeeze rollers related to the supply to the liquid carrier of this color among the photosensitive member squeeze rollers 37Y, 37M, 37C, and 37K and the intermediate transfer belt squeeze roller pair 43Y, 43M, 43C, and 43K. You can do it. Furthermore, the reverse bias may be applied only to the squeeze roller closest to the secondary transfer roller 46 (in the above example, the black intermediate transfer belt squeeze roller pair 43K).

  Further, as a method of supplying a large amount of liquid carrier to the secondary transfer roller 46, when applying a reverse bias when executing the foreign matter removal mode as described above, each of the photoconductor squeeze rollers 37Y, 37M, 37C, and 37K is set. Each of the intermediate transfer belt squeeze roller pairs 43Y, 43M, 43C, and 43K is brought into contact with the intermediate transfer belt 10 at the time of executing the foreign matter removal mode. At least one of the photosensitive member squeeze rollers 37Y, 37M, 37C, and 37K is separated from the corresponding photosensitive member 2Y, 2M, 2C, and 2K, or at least one of the intermediate transfer belt squeeze roller pairs 43Y, 43M, 43C, and 43K. One can also be separated from the intermediate transfer belt 10. In this way, it is not necessary to apply a reverse bias to the photosensitive member squeeze rollers 37Y, 37M, 37C, and 37K and the intermediate transfer belt squeeze roller pair 43Y, 43M, 43C, and 43K, and a larger amount of liquid carrier is supplied to the secondary. It can be supplied to the transfer roller 46. In particular, in this squeeze roller separation method, since the amount of liquid carrier supplied to the secondary transfer roller 46 is larger than the application of the reverse bias, the intermediate transfer belt squeeze roller pair closest to the secondary transfer roller 46 (described above). In this example, it is desirable to separate only the intermediate transfer belt squeeze roller pair 43K) from the intermediate transfer belt 10. Further, at the time of executing the foreign matter removal mode, at least one of the squeeze roller cleaners 38Y, 38M, 38C, and 38K may be separated from the corresponding photosensitive member squeeze rollers 37Y, 37M, 37C, and 37K. At least one of the belt squeeze roller cleaners 44Y, 44M, 44C, 44K may be separated from the corresponding intermediate transfer belt squeeze roller pair 43Y, 43M, 43C, 43K.

In the above example, the liquid application device 19 is provided. However, the liquid application device 19 is not always necessary and can be omitted.
Further, in the above-described example, the image forming apparatus of the present invention is applied to the tandem type full-color image forming apparatus 1 using the intermediate transfer belt, but the present invention is not limited to this. Any other image forming apparatus, such as a monochrome image forming apparatus or an image forming apparatus that does not use an intermediate transfer medium, can be used as long as it is an image forming apparatus that performs development with a liquid developer composed of toner and a liquid carrier. Can be applied.

  In the image forming apparatus of the present invention, a toner image obtained by developing an electrostatic latent image with a liquid developer composed of toner and a liquid carrier is carried on a transfer material such as paper, and the liquid developer image is carried. For example, it can be suitably used for an image forming apparatus such as a copying machine, a facsimile machine, a printer, etc., which obtains an image by transfer using a transfer roller that contacts a toner image carrier such as a photoconductor, an intermediate transfer belt, and an intermediate transfer roller. .

1 is a diagram schematically and partially showing an example of an embodiment of an image forming apparatus according to the present invention. FIG. 2 is a view for explaining collection of a liquid carrier in the image forming apparatus of the example shown in FIG. 1. Explaining the execution of the foreign substance removal mode, (a) is a diagram showing a state before the liquid carrier of the white solid image is applied to the secondary transfer roller, (b) is the state of the liquid carrier of the white solid image to the secondary transfer roller It is a figure which shows the state in application. FIG. 2 is a diagram illustrating a flow for setting a foreign matter removal mode in the image forming apparatus illustrated in FIG. 1. It is a figure explaining the foreign substance removal mode execution control means for performing foreign substance removal mode. It is a figure explaining the sequence control performed in a foreign material removal mode.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 2Y, 2M, 2C, 2K ... Each color photoconductor, 5Y, 5M, 5C, 5K ... Each color developing device, 6Y, 6M, 6C, 6K ... Photoconductor squeeze device, 7Y, 7M, 7C , 7K ... primary transfer device for each color, 10 ... intermediate transfer belt, 11 ... drive roller, 13Y, 13M, 13C, 13K ... intermediate transfer belt squeeze device, 14 ... secondary transfer device, 15 ... intermediate transfer belt cleaning device, 16 ... Paper, 18 ... Registration roller pair, 19 ... Liquid coating device, 23Y, 23M, 23C, 23K ... Development roller cleaner for each color, 25Y, 25M, 25C, 25K ... Liquid developer for each color, 37Y, 37M, 37C, 37K ... Photosensitive squeeze rollers, 40Y, 40M, 40C, 40K ... Primary transfer rollers, 43Y, 43M, 43C, 43K ... Intermediate transfer belt squeeze roller pairs, 46 ... Secondary transfer rollers, 47 ... Next transfer roller cleaner, 51 ... pick-up roller, 75 ... foreign matter removal mode execution control means, 76 ... controller, 77 ... jam detecting means

Claims (9)

A latent image carrier on which an electrostatic latent image is formed, and development that forms the developer image on the latent image carrier by developing the electrostatic latent image with a liquid developer composed of toner and a non-volatile liquid carrier. An image forming apparatus comprising at least an image forming apparatus and a transfer device that transfers a developer image on the latent image carrier to a conveyed transfer material by a transfer roller that contacts the latent image carrier at the time of image formation. ,
The transfer device includes a transfer roller cleaning member that contacts the transfer roller and cleans the transfer roller;
A foreign matter removal mode is set to remove the foreign matter attached to the transfer roller and the foreign matter attached to and deposited on the transfer roller cleaning member by attaching the liquid carrier to the transfer roller in a larger amount than in a normal image forming operation. And the foreign matter removal mode is executed when the foreign matter removal mode start condition is satisfied.   The latent image carrier so that a large amount of liquid carrier adheres from the latent image carrier to the transfer roller when the transfer material is not positioned at the contact portion between the latent image carrier and the transfer roller. 2. A foreign matter removal mode execution control means is provided for controlling the operation of the body, the developing device, the transfer device, and the transfer roller cleaning member to execute the foreign matter removal mode. Image forming apparatus. A latent image that squeezes the developer image on the latent image carrier by applying a forward bias of the same polarity as the polarity of the toner applied between the transfer device and the developing device. It has a carrier squeeze member,
3. The image forming apparatus according to claim 2, wherein a reverse bias having a polarity opposite to the polarity of the toner is applied to the latent image carrier squeeze member when the foreign matter removal mode is executed. Development in which a latent image carrier on which an electrostatic latent image is formed and development of the electrostatic latent image with a liquid developer comprising toner and a non-volatile liquid carrier to form a developer image on the latent image carrier A developer image on the intermediate transfer medium by an apparatus, a primary transfer device that primarily transfers the developer image on the latent image carrier to the intermediate transfer medium, and a secondary transfer roller that contacts the intermediate transfer medium during image formation In an image forming apparatus comprising at least a secondary transfer device for secondary transfer to a transfer material being conveyed,
The secondary transfer device includes a secondary transfer roller cleaning member that contacts the secondary transfer roller and cleans the secondary transfer roller,
By adhering a larger amount of the liquid carrier to the secondary transfer roller than during normal image forming operation, the foreign matter adhering to the secondary transfer roller and the foreign matter adhering to and depositing on the secondary transfer roller cleaning member are removed. An image forming apparatus, wherein a foreign matter removal mode is set and the foreign matter removal mode is executed when a foreign matter removal mode start condition is satisfied.   When the transfer material is not located at a contact portion between the intermediate transfer medium and the secondary transfer roller, the latent transfer is performed so that a large amount of liquid carrier is attached from the intermediate transfer medium to the secondary transfer roller. Foreign matter removal mode execution control for controlling the operation of the image carrier, the developing device, the primary transfer device, the intermediate transfer medium, the secondary transfer device, and the secondary transfer roller cleaning member to execute the foreign matter removal mode. 5. The image forming apparatus according to claim 4, further comprising means. A latent bias that squeezes the developer image on the latent image carrier by applying a forward bias of the same polarity as the polarity of the toner is applied between the primary transfer device and the developing device. While having an image carrier squeeze member,
An intermediate in which a forward bias having the same polarity as the polarity of the toner is applied between the primary transfer device and the secondary transfer device to squeeze the developer image on the intermediate transfer medium. A transfer medium squeeze member,
6. The image forming apparatus according to claim 5, wherein a reverse bias having a polarity opposite to the polarity of the toner is applied to the latent image carrier squeeze member and the intermediate transfer medium squeeze member when the foreign matter removal mode is executed. . Yellow, magenta, cyan, and black electrostatic latent images on which yellow, magenta, cyan, and black electrostatic latent images are formed, respectively, and the yellow, magenta, cyan, and black electrostatic latent images Are developed with yellow, magenta, cyan, and black toners and a non-volatile liquid carrier, respectively, with yellow, magenta, cyan, and black liquid developers, respectively. Yellow, magenta, cyan, and black developing devices that form yellow, magenta, cyan, and black developer images on the latent image carrier, and the yellow, magenta, cyan, and black latent images, respectively. Yellow to primarily transfer each developer image on the body to an intermediate transfer medium, Secondary transfer of the developer image on the intermediate transfer medium onto the transported transfer material is performed by a primary transfer device of magenta, cyan, and black and a secondary transfer roller that contacts the intermediate transfer medium during image formation. At least a secondary transfer device, and the latent image carriers are arranged in tandem in any order along the intermediate transfer medium, and are sequentially overlaid on the intermediate transfer medium to form a full-color developer image. In the image forming apparatus
The secondary transfer device includes a secondary transfer roller cleaning member that contacts the secondary transfer roller and cleans the secondary transfer roller,
By adhering a larger amount of the liquid carrier to the secondary transfer roller than during normal image forming operation, the foreign matter adhering to the secondary transfer roller and the foreign matter adhering to and depositing on the secondary transfer roller cleaning member, respectively. An image forming apparatus, wherein a foreign matter removal mode to be removed is set and the foreign matter removal mode is executed when a foreign matter removal mode start condition is satisfied.   The latent image is formed so that a large amount of liquid carrier is attached from the intermediate transfer medium to the secondary transfer roller when the transfer material is not positioned at a contact portion between the intermediate transfer medium and the secondary transfer roller. Foreign matter removal mode execution control means for controlling the operation of the carrier, the developing device, the primary transfer device, the intermediate transfer medium, the secondary transfer device, and the secondary transfer roller cleaning member to execute the foreign matter removal mode. The image forming apparatus according to claim 7, wherein the image forming apparatus is provided. Each of the latent images of yellow, magenta, cyan, and black is carried between the primary transfer devices of yellow, magenta, cyan, and black and the developing devices of yellow, magenta, cyan, and black, respectively. Each yellow, magenta, cyan, and black latent image carrier squeeze member that squeezes the developer image on each latent image carrier by applying a forward bias of the same polarity as the polarity of the toner while contacting the body With
Of the primary transfer devices of yellow, magenta, cyan, and black, the primary transfer device of the first color located most upstream in the rotation direction of the intermediate transfer medium and the next upstream side in the rotation direction of the intermediate transfer medium The first color developer on the intermediate transfer medium is applied with a forward bias having the same polarity as that of the toner in contact with the intermediate transfer medium between the primary transfer device of the second color positioned at Between the first intermediate transfer medium squeeze member for squeezing the image, the primary transfer device for the second color, and the primary transfer device for the third color located further upstream in the rotational direction of the intermediate transfer medium. A second intermediate transfer medium squeeze member that abuts on the intermediate transfer medium and is applied with a forward bias having the same polarity as that of the toner to squeeze the second color developer image on the intermediate transfer medium; Said Between the primary transfer device of three colors and the primary transfer device of the fourth color positioned further upstream in the rotational direction of the intermediate transfer medium, the same polarity as the polarity of the toner is in contact with the intermediate transfer medium And a third intermediate transfer medium squeeze member that squeezes the third color developer image on the intermediate transfer medium by applying a forward bias, and a fourth transfer primary transfer device and a secondary transfer roller. A fourth intermediate transfer medium squeeze member that squeezes the fourth color developer image on the intermediate transfer medium by applying a forward bias having the same polarity as that of the toner in contact with the intermediate transfer medium. And
At the time of executing the foreign matter removal mode, at least one of the yellow, magenta, cyan, and black latent image carrier squeeze members and the first to fourth intermediate transfer medium squeeze members has a polarity opposite to that of the toner. 9. The image forming apparatus according to claim 8, wherein a reverse bias of polarity is applied.

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