JP2006251527A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus of a wet fixing system capable of imparting a fixing solution in a contactless state only to the image part attached with a toner image in a toner image carrier, reducing the amount of consumption of the fixing solution to a necessary minimum without the occurrence of an image disturbance, and forming a satisfactory image for a long period. <P>SOLUTION: The image forming apparatus 1 of the wet fixing system includes a toner image forming means 2, an intermediate transfer means 3 having an intermediate transfer belt 21 which is the toner image carrier, a transfer fixing means 6, a recording medium supply means 7, and a discharge means 8. The apparatus is provided with a fixing solution imparting means 4 and a fixing solution recovering means 5, and the fixing solution 29 is discharged from the fixing solution imparting means 4 in nearly parallel to a toner image carrying surface 21a of the intermediate transfer belt 21, and thereby the fixing solution 29 is imparted only to the toner image. The fixing solution 29 not attached to the toner image is recovered by the fixing solution recovering means 5 and is recycled. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus.

  In an electrophotographic image forming apparatus, which is often used in copying machines, printers, facsimiles, etc., a photoreceptor having a photosensitive layer containing a photoconductive material formed on the surface is used, and a charge is applied to the surface of the photoreceptor. After charging uniformly, an electrostatic latent image corresponding to image information is formed by various image forming processes, and a developer containing toner is supplied to the electrostatic latent image from a developing unit and developed. An image is formed on the recording medium by transferring the toner image to a recording medium such as paper directly or via an intermediate transfer medium, and fixing the toner image transferred to the recording medium to the recording medium. .

  For fixing a toner image to a recording medium, a thermal fixing method for heating the toner image, a wet fixing method for applying a fixing solution for softening and / or swelling the toner to the toner image, and the like are known. Among these, in the wet fixing method, a toner image softened and / or swollen by applying a fixing solution is attached to a recording medium and pressed to fix the toner image on the recording medium. The wet fixing method has an advantage that it consumes much less power than the thermal fixing method, and many proposals have been made.

  For example, a toner image forming unit that forms a toner image, a toner image carrier that carries a toner image formed by the toner image forming unit, and a fixing solution that dissolves or swells the toner is supported on the toner image carrier. A material having a liquid repellency with respect to a fixing liquid, comprising: a fixing liquid applying means that contacts and coats the surface with a coating roller; and a transfer means that transfers a toner image dissolved or swollen by the fixing liquid applying means onto a recording medium. An image forming apparatus using a toner image carrier composed of the above is proposed (for example, see Patent Document 1). In this image forming apparatus, by utilizing the affinity between the fixing solution and the toner and the liquid repellency of the toner image carrier with respect to the fixing solution, the contact-fixing solution is applied to the toner image carrying surface of the toner image carrier. It is configured so that it adheres only to the image portion that is the toner adhering portion and does not adhere to the non-image portion where the toner does not adhere.

  Patent Document 1 also discloses a configuration in which a contact roller that contacts the toner image carrier is further provided, and the fixing liquid that slightly adheres to the non-image portion of the toner image carrier is collected by the contact roller.

  According to Patent Document 1, by adopting the above-described configuration, the consumption of the fixing solution is minimized, and wrinkles generated on the recording medium due to the amount of the fixing solution adhering to the recording medium being too large. Prevents curling.

  However, according to the image forming apparatus of Patent Document 1, since the toner image on the toner image carrier directly contacts members such as the application roller and the contact roller, the toner adheres to the application roller and the contact roller, and the fixing is performed. A part of the toner image may flow due to the liquid, and the finally formed image may be disturbed.

  Therefore, although it is desirable to apply the fixing liquid to the toner image in a non-contact manner, the non-contact application causes a problem that the fixing liquid adheres to the non-image portion. The adhesion of the fixing liquid to the non-image area leads to an increase in the consumption of the fixing liquid, wrinkles on the recording medium, curling, and the like. In order to remove the fixing liquid in the non-image area, for example, it is most realistic to use a contact roller. However, the use of the contact roller has a problem that the toner adheres to the contact roller and the image is disturbed as described above. There has also been proposed a method of removing the fixing solution adhering to the non-image area by blowing air. However, in this method, it is difficult to control the flying direction of the fixing liquid removed from the non-image area by air, and the inside of the image forming apparatus may be contaminated with the fixing liquid. Further, the use of air in the image forming apparatus may cause a turbulent air flow, causing toner scattering in the apparatus and contaminating the recording medium.

JP 2004-109747 A

  An object of the present invention is to apply a fixing solution in a non-contact state only to an image portion on which a toner image adheres on a toner image carrier, and to minimize the consumption of the fixing solution without causing image distortion. It is an object of the present invention to provide a wet fixing type image forming apparatus capable of forming a good image over a long period of time.

The present invention
A toner image forming means for forming a toner image comprising a toner containing a binder resin and a colorant;
In a toner image carrier that carries and rotates a toner image formed by toner image forming means, at least the toner image carrier surface is made of a material that does not penetrate a fixing liquid that softens and / or swells the toner image. Body,
A fixing solution applying means for applying a fixing solution to the toner image on the toner image carrier in a non-contact manner;
A fixing liquid recovery means for recovering the fixing liquid that does not adhere to the toner image carrier in a non-contact manner with respect to the toner image carrier;
An image forming apparatus comprising: a transfer fixing unit that fixes a toner image to which a fixing liquid is applied to a recording medium at the same time as transfer.

The image forming apparatus of the present invention also has
The fixing liquid applying unit discharges the fixing liquid substantially parallel to the toner image carrying surface of the toner image carrier.

Furthermore, the image forming apparatus of the present invention is
The fixing liquid applying unit discharges the fixing liquid to at least one of a plurality of support roller contact portions of a toner image carrier that is an endless belt that is rotatably stretched around the plurality of support rollers.

Furthermore, the image forming apparatus of the present invention is
The fixing liquid applying unit includes a drying preventing unit that is provided in the vicinity of a fixing liquid discharge port where the fixing liquid is exposed to the atmosphere and prevents evaporation of a liquid component in the fixing liquid.

Furthermore, the image forming apparatus of the present invention is
The drying prevention means is a shutter means provided so as to be openable and closable, and blocking the fixing liquid discharge port from the atmosphere.

Furthermore, the image forming apparatus of the present invention is
At least the toner image carrying surface of the toner image carrying member is made of a material having liquid repellency with respect to the fixing solution.

Furthermore, the image forming apparatus of the present invention is
The fixing solution collecting unit includes a fixing solution circulating unit that circulates the collected fixing solution to the fixing solution applying unit.

Furthermore, the image forming apparatus of the present invention is
The fixing solution collecting unit is arranged at a position higher than the fixing solution applying unit.

Furthermore, the image forming apparatus of the present invention is
The fixing liquid recovery means is a plate-like recovery member for attaching and recovering a fixing liquid that does not adhere to the toner image carrying surface of the toner image carrier among the fixing liquid discharged from the fixing liquid applying means; It includes a recovery member provided to be inclined with respect to a horizontal plane.

Furthermore, the image forming apparatus of the present invention is
The fixing solution applying unit and the fixing solution collecting unit are housed in one casing.
The housing is for inserting at least a part of the toner image carrying surface of the toner image carrying body into the housing and discharging the fixing solution from the fixing solution discharge port of the fixing solution applying means toward the toner image carrying surface. It has the opening part of this.

  Furthermore, the image forming apparatus of the present invention is characterized in that the binder resin is a polyester resin.

  Furthermore, the image forming apparatus of the present invention is characterized in that the volume average particle diameter of the toner is 2 μm or more and 7 μm or less.

  According to the present invention, in a toner image forming unit that forms a toner image and a toner image carrier that rotates while carrying a toner image, at least the toner image carrying surface penetrates a fixing liquid that softens and / or swells the toner image. A non-contact toner image carrier, a fixing liquid application means for applying a non-contact fixing solution to the toner image on the toner image carrier, and a non-contact fixing solution that does not adhere to the toner image carrier. There is provided an image forming apparatus including a fixing solution collecting unit for collecting, and a transfer fixing unit for fixing a toner image to a recording medium simultaneously with transfer.

  The image forming apparatus of the present invention can selectively apply a fixing solution to a toner image without causing image distortion, despite employing a wet fixing method that applies a fixing solution to a toner image in a non-contact manner. And the consumption of the fixing solution can be minimized and a good image can be formed over a long period of time. Further, since the fixing solution applying unit and the fixing solution collecting unit can be implemented as one process, for example, by forming both units as one unit, the fixing solution can be obtained without increasing the size and complexity of the apparatus. Can be easily applied to the toner image without contact.

  According to the present invention, the fixing liquid applying means is configured to discharge the fixing liquid substantially in parallel with the toner image carrying surface of the toner image carrier, so that the fixing liquid is applied to the toner image carrying surface as in the prior art. Since the supply angle (incident angle of the fine droplets) of the fine droplets of the fixing liquid to the toner image carrying surface can be made smaller than the case where the liquid droplets are ejected perpendicularly to the toner, the toner image carrying surface does not penetrate the fixing liquid. In combination, the liquid droplets of the fixing liquid can be repelled from the toner image carrying surface and collected. In other words, if the fixer has excellent affinity with toner, the fixer supplied to the toner image that is an aggregate of toners adheres to the toner image as it is and is supplied to the non-image portion other than the toner image. The fixing solution does not adhere as it is and repels away from the toner image carrier, so that the fixing solution can be selectively applied only to the image portion that is the toner image. It can be recovered by means. Accordingly, the consumption of the fixing solution can be minimized, and the application and collection of the fixing solution are performed in a non-contact manner, and image distortion is not caused. Further, when the fixing liquid is ejected substantially parallel to the toner image carrying surface, the liquid droplets passing through the upper part without contacting the toner image carrying body increase. And it won't be wasted if you reuse it. Furthermore, since the discharge direction of the fixing liquid is a constant direction, the repulsion direction from the toner image carrier is also substantially constant, and the fixing liquid can be easily collected.

  According to the present invention, the toner image carrier is configured as an endless belt stretched by a plurality of support rollers, and the fixing liquid is applied to at least one portion of the contact portion of the toner image carrier with the plurality of support rollers. By discharging, it becomes easy to dispose the fixing solution applying unit and the fixing solution collecting unit, and the size and complexity of the apparatus can be prevented. In other words, the toner image carrier is in a bent state at the contact portion between the toner image carrier, which is an endless belt, and the support roller, and the fixing liquid is applied to a part of the toner image carrier (the part where the toner image is attached). In such a case, if there is such a bent portion, it becomes possible to apply the fixing solution locally, and the arrangement of the fixing solution applying means and the fixing solution collecting means becomes easy. In particular, in the case of applying the fixing liquid by discharging it parallel to the toner image carrying surface, if there is a bent portion as described above, the fixing liquid applying means and the fixing liquid are located at a position that does not interfere with the toner image carrying body. A collection means can be arranged.

  According to the present invention, it is preferable to provide a drying prevention means in the vicinity of the fixing liquid discharge port of the fixing liquid applying means. That is, at the fixing solution discharge port, the fixing solution is exposed to the atmosphere, and the liquid component of the fixing solution is evaporated and consumed wastefully. Therefore, a dry prevention means is provided to prevent evaporation of the liquid component of the fixing solution. Is good.

  According to the present invention, as the aforementioned dry prevention means, a shutter means that can be opened and closed is provided in the vicinity of the fixing liquid discharge port, so that when the image is not formed, the shutter means is closed and the atmosphere and the fixing liquid discharge port are shut off. As a result, the liquid component of the fixing solution can be prevented from evaporating.

  According to the present invention, at least the toner image carrying surface of the toner image carrying member is made of a material having liquid repellency with respect to the fixing solution, whereby the toner image of the droplet of the fixing solution supplied to the non-image portion. The releasability from the carrier is further improved, and the fixing liquid can be applied only to the toner image more efficiently.

  According to the present invention, by including the fixing liquid circulating means for returning the fixing liquid recovered by the fixing liquid recovery means to the fixing liquid applying means, wasteful consumption of the fixing liquid is eliminated and effective use is possible. As a result, the capacity of the fixing liquid storage tank in the image forming apparatus can be reduced, and the image forming apparatus is not increased in size and complexity. In addition, the fixer replenishment cycle can be extended, and the maintainability is improved.

  According to the present invention, in the image forming apparatus of the present invention, the fixing liquid recovered by the fixing liquid recovery means is returned to the fixing liquid applying means by providing the fixing liquid recovery means at a position higher than the fixing liquid applying means. In addition, since it can be returned using gravity, a new power for returning the fixing liquid becomes unnecessary.

  According to the present invention, the fixing liquid collecting means is provided above the fixing liquid applying means and the toner image carrier so as to be inclined with respect to the horizontal plane, and does not adhere to the toner image carrying surface of the toner image carrier. By including a plate-like recovery member that collects and recovers the fixing liquid, the fixing liquid adhering to the recovery member flows in one direction along the inclination, so that the fixing liquid can be easily recovered.

  According to the present invention, the fixing solution applying unit and the fixing solution collecting unit are accommodated in one housing, and at least a part of the toner image carrying surface of the toner image carrying member is inserted into the housing. By providing an opening for discharging the fixing liquid from the fixing liquid applying unit toward the toner image carrying surface, scattering of the fixing liquid to other than the toner image carrying surface, and thus contamination inside the image forming apparatus by the fixing liquid. Can be prevented.

  According to the present invention, it is preferable that the binder resin of the toner used in the image forming apparatus of the present invention is polyester. Polyester can be softened and / or swelled by an inexpensive and common organic solvent, so that the organic solvent as described above can be used as a fixing solution component, and the cost of the fixing solution can be reduced. In addition, since polyester becomes transparent in a softened or swollen state, when a color toner image is formed by superimposing several color toner images, a vivid color can be obtained by subtractive color mixing.

  According to the present invention, it is preferable to use toner having a volume average particle diameter of 2 to 7 μm as the toner used in the image forming apparatus of the present invention. If the particle size is less than 2 μm, the fluidity as a toner is lowered, and stirring and charging in the developing device and supply of the toner to the electrostatic latent image cannot be carried out smoothly. As a result, an increase in reverse polarity toner, a shortage of toner amount, and the like occur, and a high-quality toner image cannot be obtained when developing an electrostatic latent image. When the particle diameter exceeds 7 μm, it becomes difficult to swell to the center of the toner particles, the color of the fixed image is deteriorated, and the transmitted image of OHP becomes dark.

  FIG. 1 is a cross-sectional view schematically showing a configuration of an image forming apparatus 1 according to a first embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view showing a configuration of a main part (a toner image forming unit 2 described later) of the image forming apparatus 1 shown in FIG. FIG. 3 is an enlarged cross-sectional view showing the structure of the main parts (intermediate transfer means 3, fixing solution applying means 4, transfer fixing means 5 and discharge section 7 described later) of the image forming apparatus 1 shown in FIG.

  The image forming apparatus 1 includes a toner image forming unit 2, an intermediate transfer unit 3, a fixing solution applying unit 4, a fixing solution collecting unit 5, a transfer fixing unit 6, a recording medium supplying unit 7, and a discharging unit 8. It is comprised including.

  The toner image forming unit 2 includes image forming units 10y, 10m, 10c, and 10b, which form an electrostatic latent image corresponding to image information of each hue, develop the electrostatic latent image, and develop each electrostatic color image. A toner image is formed. That is, the image forming unit 10y forms a toner image corresponding to yellow image information, the image forming unit 10m forms a toner image corresponding to magenta image information, and the image forming unit 10c uses cyan image information. The image forming unit 10b forms a toner image corresponding to black image information.

  The image forming unit 10y includes a photosensitive drum 11y, a charging roller 12y, an optical scanning unit 13, a developing device 14y, and a drum cleaner 15y.

  The photosensitive drum 11y is supported by a driving unit (not shown) so as to be rotatable around an axis, and includes a cylindrical, columnar, or thin film sheet (preferably cylindrical) conductive substrate (not shown) and the surface of the conductive substrate. And a photosensitive layer formed thereon. As the photosensitive drum 11y, those commonly used in this field can be used. For example, the photosensitive drum 11y is connected to a GND potential including an aluminum base tube as a conductive substrate and an organic photosensitive layer formed on the surface of the aluminum base tube. And a photosensitive drum having a diameter of 30 mm. The organic photosensitive layer is formed by laminating a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material. The organic photosensitive layer may include a charge generation material and a charge transport material in one layer. The layer thickness of the organic photosensitive layer is, for example, 20 μm. An underlayer may be provided between the organic photosensitive layer and the conductive substrate. Further, a protective layer may be provided on the surface of the organic photosensitive layer. Instead of the organic photosensitive layer, a photosensitive layer made of zinc oxide, selenium, amorphous silicon or the like can be used. The photosensitive drum 11y is rotationally driven in a clockwise direction, for example, at a peripheral speed of 100 mm / s.

  The charging roller 12y charges the surface of the photosensitive drum 11y to a predetermined polarity and potential. Instead of the charging roller 12y, a brush type charger, a charger type charger, a corona charger such as a scorotron, or the like can be used. In the present embodiment, the photosensitive drum 11y is charged to −600V.

  The optical scanning unit 13 irradiates the surface of the photosensitive drum 11y to be charged with laser light 13y corresponding to yellow image information, and electrostatically corresponds to the yellow image information on the surface of the photosensitive drum 11y. A latent image is formed. A semiconductor laser or the like is used as the light source of the laser beam 13y. In the present embodiment, an electrostatic latent image having an exposure potential of −70 V is formed.

  The developing device 14y is in pressure contact with the surface of the photosensitive drum 11y, includes a fixed magnetic pole (not shown), and is rotatably driven around an axis, and supplies yellow toner 16y to the electrostatic latent image on the surface of the photosensitive drum 11y. A developing roller 17y, a developing blade 18y that is provided so as to be in contact with the surface of the developing roller 17y, uniformizes the layer of yellow toner on the surface of the developing roller 17y (layer regulation), and a toner storage container that stores the yellow toner 16y. 19y and a stirring roller 20a, 20b provided in the toner storage container 19y so as to be in pressure contact with each other and rotatably driven around the axis, the stirring roller 20a being in pressure contact with the surface of the developing roller 17y and the surface of the developing roller 17y And stirring rollers 20a and 20b for supplying yellow toner 16y. The developing roller 17y is rotationally driven in the same direction as the rotational driving direction of the photosensitive drum 11y at a developing nip portion that is in pressure contact (contact) with the photosensitive drum 11y. Therefore, the rotational drive direction around the axis is the opposite direction. In the present embodiment, the peripheral speed of the developing roller 17y is, for example, 150 mm / s, which is 1.5 times that of the photosensitive drum 11y. In the present embodiment, a DC voltage of −240 V is applied to the developing roller 11y as the developing potential. The yellow toner 16y in the toner storage container 19y is supplied to the surface of the developing roller 17y by the stirring rollers 20a and 20b, and after the layer thickness is uniformized by the developing blade 18y, the surface of the photosensitive drum 11y is utilized by utilizing a potential difference or the like. The electrostatic latent image is selectively supplied to the toner image corresponding to the yellow image information. In this embodiment, it is used as a two-component developer in which yellow toner 16y and a magnetic carrier are mixed.

  As will be described later, the drum cleaner 15y removes and collects the yellow toner remaining on the surface after the yellow toner image on the surface of the photosensitive drum 11y is transferred to the intermediate transfer belt 21.

  According to the image forming unit 10y, the surface of the photosensitive drum 11y is first charged to, for example, -600V by the charging roller 12y while the photosensitive drum 11y is rotated about its axis. Next, the surface of the charged photosensitive drum 11y is irradiated with signal light corresponding to yellow image information from the optical scanning unit 13, and an electrostatic latent having an exposure potential of −70 V corresponding to the yellow image information. Form an image. Next, the yellow toner layer carried on the surface of the developing roller 16y comes into contact with the surface of the photosensitive drum 11y. A DC voltage of −240 V is applied to the developing roller 16y as a developing potential. Due to the potential difference, the yellow toner 16y adheres to the electrostatic latent image and is developed, and a yellow toner image is formed on the surface of the photosensitive drum 11y. Is formed. As will be described later, this yellow toner image is intermediately transferred to an intermediate transfer belt 21 in contact with the surface of the photosensitive drum 11y. The yellow toner 16y remaining on the surface of the photosensitive drum 11y is removed and collected by the drum cleaner 15y. Thereafter, the same yellow toner image forming operation is repeatedly executed.

  The image forming units 10m, 10c, and 10b have the same structure as the image forming unit 10y except that magenta toner 16m, cyan toner 16c, and black toner 16b are used. Further, “m” indicating magenta color, “c” indicating cyan color, or “b” indicating black color is added to the end of each reference symbol, and the description is omitted. The image forming units 10y, 10m, 10c, and 10b are arranged in a line in this order from the upstream side in the direction of movement of the intermediate transfer belt 21 (sub-operation direction), that is, the direction of the arrow 27.

  Each of the color toners 16y, 16m, 16c, and 16b contains a binder resin, a colorant, and, if necessary, a release agent.

  The binder resin is not particularly limited as long as the resin is softened and / or swollen by the fixing solution 29 described later. For example, polystyrene, a homopolymer of a substituted styrene, a styrene copolymer, polyvinyl chloride, Examples thereof include polyvinyl acetate, polyethylene, polypropylene, polyester, and polyurethane. Binder resins can be used alone or in combination of two or more. Among these, the softening point is 100 to 150 ° C. and the glass transition point is 50 to 80 ° C. from the viewpoints of storage stability and durability of the toner itself, softening and / or swelling control of the toner by applying the fixing liquid 29, and the like. Resins are preferred, and polyesters are particularly preferred. Polyesters easily swell and / or soften and become transparent with readily available and inexpensive organic solvents. Thus, when a color toner image obtained by superimposing different single color toner images is fixed on a recording medium, sufficient color development can be obtained by subtractive color mixing. In addition, when a resin having a softening point (or molecular weight) higher than that of the above-mentioned softening point range is used, toner deterioration due to a load during development is prevented, and the developed toner image that is stable over a long period of time and thus stable at a high level. An image is obtained.

  As the colorant, although pigments and dyes for toners conventionally used in electrophotographic image forming technology can be used, a pigment that does not dissolve in the fixing solution 29 is preferable in order to prevent bleeding by the fixing solution 29, and a nigrosine dye Dyes such as are not preferred. Specific examples of the pigment include, for example, azo pigments, benzimidazolone pigments, quinacridone pigments, phthalocyanine pigments, isoindolinone pigments, isoindoline pigments, dioxazine pigments, anthraquinone pigments, perylene pigments, Organic pigments such as perinone pigments, thioindigo pigments, quinophthalone pigments, metal complex pigments, inorganic pigments such as carbon black, titanium oxide, molybdenum red, chromium yellow, titanium yellow, chromium oxide, Berlin blue, aluminum powder And metal powders.

  The release agent is not particularly limited as long as it is softened and / or swelled by the fixing solution 29 described later, and examples thereof include waxes such as polyethylene wax, polypropylene wax, and paraffin wax. Among these waxes, it is preferable to use a wax having a glass transition point lower than that of the binder resin depending on the binder resin to be used. Wax having a glass transition point lower than that of the binder resin is easily softened by heating. Therefore, even at a temperature lower than the glass transition point of the toner itself, the bonding force between the toners and the adhesion of the toner to the toner image carrier, recording medium, etc. Since the adhesion force is increased, it is possible to reduce the occurrence of toner flow, aggregation and the like when the fixing solution is applied. Further, the softening of the wax causes the fixing liquid 29 to permeate into the toner particles from the wax-existing portion of the toner particles, so that the entire toner is softened and / or swelled in a short time after the fixing liquid 29 is applied. As a result, at the time of transfer and fixing to a recording medium, sufficient fixing strength can be obtained, and sufficient color development can be obtained by superimposing toner images.

  The toner can contain one or more general toner additives such as a charge control agent, a fluidity improver, a fixing accelerator, and a conductive agent, if necessary.

  The volume average particle diameter of the toner is not particularly limited, but is preferably 2 to 7 μm. When such a toner having a small particle diameter is used, the surface area of the toner per unit weight is increased, and the contact area with the fixing liquid 29 is increased to facilitate fixing. As a result, the amount of the fixing liquid 29 used can be reduced, and the fixing of the toner image onto the recording medium and the drying after the fixing can be performed in a short time. Further, when the volume average particle diameter of the toner is appropriately small, the coverage with respect to the recording medium 9 is increased, so that it is possible to achieve high image quality with a low adhesion amount and a reduction in toner consumption. Further reduction in consumption can be achieved.

  When the volume average particle diameter of the toner is less than 2 μm, the fluidity of the toner is lowered, and during the developing operation, the toner supply, agitation and charging become insufficient, the toner amount is insufficient, and the reverse polarity toner is increased. This may occur and a high-quality image may not be obtained. On the other hand, if the volume average particle size exceeds 7 μm, the toner particles having a large particle size that is difficult to soften and / or swell to the center of the toner particles increase, so that the fixability of the image to the recording medium is reduced and the image Color development deteriorates, and the image becomes dark particularly when fixing to an OP film.

  Although the softening point and glass transition point of the toner itself are not particularly limited, the softening point is preferably 100 to 130 ° C and the glass transition point is preferably 50 to 80 ° C. Such a toner having a high softening point has high durability against a load during development, but does not sufficiently fix and develop color in the heat fixing method. However, in the present invention, since the toner is chemically softened and / or swollen chemically using the fixing solution 29, fixing and color development are sufficient, and a high-quality image can be obtained.

  The toner can be produced according to a known method. For example, a method of dispersing and pulverizing a colorant and a release agent in a binder resin, a method of dispersing a colorant and a release agent in a binder resin monomer solution, and then polymerizing the binder resin monomer Etc. In any method, in order to increase the surface area of the toner, it is preferable to adjust the shape of the toner to be indefinite rather than spherical. This facilitates contact with the fixing solution 29, so that the amount of the fixing solution 29 used can be reduced, and the toner image can be fixed and dried in a short time.

Each color toner 16y, 16m, 16c, and 16b used in the present embodiment has the same configuration as described below except for the pigment. This toner contains a binder resin, a colorant and a release agent, and has a volume average particle size of 6 μm, a glass transition point of 60 ° C., a softening point of 120 ° C., a pigment content of 12% by weight of the total amount of toner, and a wax as a release agent. This is a negatively chargeable insulating nonmagnetic toner having a content of 7% by weight of the total amount of toner and the balance being a binder resin. The binder resin is a polyester having a glass transition point of 60 ° C. and a softening point of 120 ° C. The wax is a low molecular weight polyethylene wax having a glass transition point of 50 ° C. and a softening point of 70 ° C. Using this toner, the amount of toner per unit area required to obtain a predetermined image density (the measured value of reflection density by X-Rite 310 is 1.4) is 0.5 mg / cm ² .

  The intermediate transfer unit 3 includes an intermediate transfer belt 21, intermediate transfer rollers 22y, 22m, 22c, and 22b, support rollers 23, 24, and 25, and a belt cleaner 26.

  The intermediate transfer belt 21 is a toner image carrier, and is an endless belt that is stretched between support rollers 23, 24, and 25 to form a loop-shaped movement path, and the photosensitive drums 11y, 11m, 11c, and 11b. Rotate in the direction of the arrow 27 at approximately the same speed. At least the toner carrying surface 21 a of the intermediate transfer belt 21 is made of a material that does not permeate the fixing liquid 29 described later, preferably a resin material that does not permeate the fixing liquid 29, and more preferably a resin material that has liquid repellency with respect to the fixing liquid 29. Formed using. Examples of the resin material having liquid repellency with respect to the fixing liquid 29 include a fluororesin. As the fluororesin, known ones can be used, and examples thereof include polytetrafluoroethylene (PTFE), a copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether (PFA), and the like. In the present embodiment, a thickness of a fluororesin composition in which a silicon layer having a thickness of 500 μm and PTFE and PFA are mixed at a weight ratio of 8: 2 on the surface of a polyimide substrate having a thickness of 100 μm. A 20 μm surface coat layer laminated in this order is used. The polyimide base material and the surface coat layer can be mixed with a conductive material such as furnace black, thermal black, channel black, and graphite carbon in order to adjust the electric resistance value as an intermediate transfer belt.

  The toner image carrying surface 21a of the intermediate transfer belt 21 is in pressure contact with the photosensitive drums 11y, 11m, 11c, and 11b in this order. The positions where the intermediate transfer belt 21 is in pressure contact with the photosensitive drums 11y, 11m, 11c, and 11b are the intermediate transfer positions of the toner images of the respective hues. Intermediate transfer rollers 22y, 22m, 22c, and 22b are disposed at positions facing the photosensitive drums 11y, 11m, 11c, and 11b via the intermediate transfer belt 21 that is a toner image carrier.

  The intermediate transfer rollers 22y, 22m, 22c, and 22b are respectively provided in pressure contact with the surface opposite to the toner image carrying surface 21a of the intermediate transfer belt 21 and rotatably driven around its axis by a driving unit (not shown). A metal shaft body and a conductive layer coated on the surface of the metal shaft body are configured. The shaft body is formed of a metal such as stainless steel, for example. The diameter of the shaft body is not particularly limited, but is preferably 8 to 10 mm. The conductive layer is formed of a conductive elastic body or the like. As the conductive elastic body, those commonly used in this field can be used, and examples thereof include EPDM, foamed EPDM, foamed urethane and the like containing a conductive material such as carbon black. A high voltage is uniformly applied to the intermediate transfer belt 21 by the conductive layer.

  The intermediate transfer rollers 22y, 22m, 22c, and 22b are opposite to the charging polarity of the toner in order to transfer the toner images formed on the surfaces of the photosensitive drums 11y, 11m, 11c, and 11b onto the intermediate transfer belt 21. A polar intermediate transfer bias is applied by constant voltage control. As a result, the yellow, magenta, cyan, and black toner images formed on the photosensitive drums 11y, 11m, 11c, and 11b are sequentially superimposed on the toner image carrying surface 21a of the intermediate transfer belt 21. Transferred to form a multicolor toner image.

  For the support rollers 23, 24, 25, for example, an aluminum cylinder having a diameter of 30 mm and a thickness of 1 mm is used. A support roller 24 that is in pressure contact with a transfer fixing roller 28 described later via the intermediate transfer belt 21 not only stretches the intermediate transfer belt 21 but also functions as a transfer fixing unit. Grounded.

  The belt cleaner 26 is a member that removes the toner remaining on the toner image carrying surface 21a after the toner image on the toner image carrying surface 21a of the intermediate transfer belt 21 is transferred to the recording medium 9 by the transfer fixing unit 6 described later. And is provided so as to face the support roller 25 via the intermediate transfer belt 21, and is pressed against the toner image carrying surface 21a of the intermediate transfer belt 21 by a pressing means (not shown), so that the residual toner on the toner image carrying surface 21a. A cleaning blade 26a that scrapes off the toner and a toner storage container 26b that stores toner scraped off by the cleaning blade 26a. For example, a blade made of a rubber material having elasticity (for example, urethane rubber) can be used as the cleaning blade 26a.

  According to the intermediate transfer means 3, the toner images of the respective colors formed on the photosensitive drums 11y, 11m, 11c, and 11b are transferred in a superimposed manner on predetermined positions on the toner image carrying surface 21a of the intermediate transfer belt 21. A color toner image is formed.

  The fixing liquid applying unit 4 applies a fixing liquid that softens and / or swells toner to the toner image carried on the intermediate transfer belt 21 in a non-contact state.

  The fixing liquid application unit 4 includes a fixing liquid application device 28 that sprays the fixing liquid 29 on a bent portion that contacts the support roller 23 of the intermediate transfer belt 21, a fixing liquid storage tank 30 that stores the fixing liquid 29, and a fixing liquid storage. A fixing liquid supply pipe 31 that supplies the fixing liquid 29 in the tank 30 to the fixing liquid applying device 28 is configured. The fixing liquid applying device 28 is disposed so that a bent portion that is in contact with the support roller 23 of the intermediate transfer belt 21 is located almost directly below the fixing liquid applying device 28.

  The fixing liquid application device 28 temporarily stores the fixing liquid discharge section 28a that discharges the fixing liquid 29 outward, and the fixing liquid reservoir that supplies the fixing liquid 29 to the fixing liquid discharging section 28a. 28b.

  Specifically, the fixing liquid applying device 28 has a structure shown in FIGS. 4 and 5. FIG. 4 is a perspective view showing the external appearance of the fixing liquid discharge section 28a of the fixing liquid application device 28. FIG. FIG. 5 is a cross-sectional view schematically showing the configuration of the fixing liquid applying device 28 shown in FIG.

  The fixing liquid applying device 28 is a device that causes the fine droplets of the fixing liquid 29 to fly toward the toner image carried on the toner image carrying surface 21a in accordance with an electrical control signal. It comprises a discharge section 28a and a fixing liquid reservoir 28b.

  In the fixing liquid discharge portion 28a, a nozzle array 51 that discharges droplets of the fixing liquid 29 is arranged in a line in a substantially parallel manner with respect to the bent toner carrying surface 21a in contact with the support roller 23 of the intermediate transfer belt 21, In addition, an ink jet head 50 having a chamber 52 in which a nozzle array 51 and a fixing liquid cartridge 53 (described later) communicate with each other, and a side surface 50b of the ink jet head 50 are provided so as to be in contact with each other. The piezoelectric element 54 which extrudes 29 and the power supply 55 which applies an expansion-contraction drive voltage to the piezoelectric element 54 are comprised. The member 56 that contacts the piezo element 54 of the inkjet head 50 is formed of ceramics. Such an inkjet head 50 is long because it is not necessary to control the discharge amount of droplets for each nozzle, and it is not necessary to form a fine nozzle diameter, unlike an inkjet head for a printer. Nevertheless, it can be made inexpensively.

  Further, the fixing liquid reservoir 28 b is provided so as to be in contact with the side surface 50 a of the inkjet head 50, and includes a fixing liquid cartridge 53 that supplies the fixing liquid 29 to the chamber 52.

  The fixing liquid applying device 28 is disposed so that a bent portion that is in contact with the support roller 23 of the intermediate transfer belt 21 is positioned almost directly below the nozzle array 51. The fixing liquid 29 is discharged from the nozzle array 51 with a radiation angle, and when the spread of the fixing liquid in a direction orthogonal to the discharge direction is defined as a discharge width, the discharge width gradually increases as the distance from the nozzle array 51 increases. Become. Accordingly, the droplets of the fixing liquid 29 pass almost parallel to the toner image carrier 21a at the bent portion and so as to graze the surface 21a, and a part of the droplet enters the toner carrying surface 21a at a shallow angle. Adhering, a part is bounced and dropped on the surface 21a, and a part falls as it is. Even when the fixing liquid 29 is ejected without a radiation angle, the ejection width is so small as to be separated from the nozzle array 51, but the droplets of the fixing liquid 29 are ejected with a radiation angle. Pass through as if. The fixing liquid application device 28 synchronizes with the timing at which the toner image is transferred to the toner image carrying surface 21 a of the intermediate transfer belt 21 and the toner image is conveyed to the bent portion by the rotation of the intermediate transfer belt 21. The discharge timing of the fixing liquid 29 can be controlled so as to discharge 29.

  According to the fixing liquid application device 28, the fixing liquid 29 in the fixing liquid cartridge 53 is supplied to the chamber 52 inside the inkjet head 50, and the fixing liquid 29 in the chamber 52 is supplied from the nozzle array 51 by the expansion / contraction driving of the piezo element 54. It is ejected as droplets and supplied to the toner image carrying surface 21 a of the intermediate transfer belt 21.

  The fixing liquid storage tank 30 is a tank for storing the fixing liquid 29 and is provided above the fixing liquid applying device 28. The fixing solution 29 in the fixing solution storage tank 30 is supplied by a control means (not shown) through the fixing solution supply pipe 31 so that the amount of the fixing solution in the fixing solution applying device 28 is constant. In addition, the amount of the fixing liquid in the fixing liquid application device 28 can be made constant by appropriately adjusting the diameter of the fixing liquid supply pipe 31 according to the set amount of the consumption of the fixing liquid 29 by the fixing liquid application device 28. .

  The fixing solution 29 used here is a liquid that softens and / or swells the toner. For example, the fixing solution 29 is a composition containing an organic compound having an action of softening and / or swelling the toner and water. The organic compound is not particularly limited as long as it has an action of softening and / or swelling the toner and can be dispersed or dissolved in water. For example, higher glycol ether, ethylene glycol monoether, diethylene glycol monoether , Ethylene glycol monomethyl ether, 2-methoxyethanol, diethylene glycol, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, butyl cellosolve ethyl carbitol, aliphatic dibasic acid esters and unsaturated dibasic acid esters (eg, DBE, maleic acid ester, Itaconic acid ester), polybasic acid ester (for example, trimellitic acid ester), ester-based high boiling point mixed solvent, and the like. These can use 1 type (s) or 2 or more types. The content of such an organic compound can be appropriately selected from a wide range depending on the kind of the organic compound itself, the toner component, and the like, but is preferably 10 to 30% by weight of the total amount of the fixing solution 29.

  A surfactant can be added to the fixing solution 29. Specific examples of the surfactant include an anionic surfactant such as a fatty acid derivative sulfate ester, a sulfonic acid type anionic surfactant and a phosphate ester, a quaternary ammonium salt, a heterocyclic amine, an amine compound and the like. Examples include ionic surfactants, amino acid esters, amino acids, amphoteric surfactants such as sulfobetaine, nonionic surfactants, polyoxyalkylene alkyl ethers, polyoxyethylene alkyl amines, and the like. The content of the surfactant can be appropriately selected from a wide range according to the type and content of the organic compound used in combination, the toner component, the type of the surfactant itself, and the like, but preferably 1 to 10% by weight of the total amount of the fixing solution 29. %.

  In this embodiment, a fixing solution 29 containing 20% by weight of higher glycol ether (organic compound) and 5% by weight of sulfonic acid type surfactant (surfactant) is used.

  According to the fixer applying unit 4, the fixer 29 filled in the fixer storage tank 30 is supplied to the fixer applying unit 28, discharged as droplets from the fixer applying unit 28, and the toner on the intermediate transfer belt 21. It is supplied to the image carrying surface 21a.

  Returning to FIG. 1, the fixing solution collecting means 5 is provided directly below the nozzle array 51 of the fixing solution applying device 28 and obliquely below the support roller 23 so as not to prevent the rotation of the intermediate transfer belt 21. The fixing liquid collecting tank 32 includes an opening 33 for storing droplets of the fixing liquid 29 that does not adhere to the toner image carrying surface 21a and falls. The fixer 29 recovered in the fixer recovery tank 32 is sent to a cartridge-type fixer storage tank (not shown). When the fixing solution storage tank is filled with the recovered fixing solution 29, the sensor detects this and sends the detection result to a CPU (not shown), and the CPU replaces the fixing solution storage tank on the operation panel of the image forming apparatus 1. Is displayed.

  According to the fixer recovery unit 5, the fixer 29 that does not adhere to the toner image carrying surface 21 a is recovered from the fixer 29 applied from the fixer applying unit 4 to the toner image carrying surface 21 a of the intermediate transfer belt 21.

  6 to 8 are side views showing a state in which the fixing liquid 29 is applied to the toner image carrying surface 21a of the intermediate transfer belt 21. FIG. FIG. 6 is a side view showing a state in which the fixing liquid 29 is applied to the non-image portion (the portion where the toner image does not adhere) of the toner image carrying surface 21a. FIG. 7 is a side view showing a state in which the fixing liquid 29 is applied to the image portion (the portion to which the toner image adheres) of the toner image carrying surface. FIG. 8 is a side view showing a state in which the fixing liquid 29 passes through the toner image carrying surface 21a without being attached.

  According to FIG. 6, the droplets of the fixing liquid 29 discharged from the fixing liquid applying device 28 are non-imaged on the toner image carrying surface 21 a at the bent portion (contact portion with the support roller 23) of the intermediate transfer belt 21. The part contacts in the direction of the arrow 57. The direction of the arrow 57 is a relatively shallow angle with respect to the toner image carrying surface 21a. In this case, the droplet is repelled by the toner image carrying surface 21a, falls in the direction of the arrow 58 without adhering to the toner image carrying surface 21a, and is collected in the fixing liquid collecting tank 32. When the fixing liquid 29 is an aqueous composition and the toner image carrying surface 21a is coated with a water repellent material such as a fluorine-based resin, the fixing liquid 29 can be more reliably prevented from adhering to non-image areas.

  According to FIG. 7, when the droplet of the fixing liquid 29 comes into contact with the image portion 21b of the toner image carrying surface 21a in the bent portion of the intermediate transfer belt 21 in the direction of the arrow 57, the fixing liquid 29 has an affinity for the toner. Therefore, the toner penetrates into the image portion 21b and softens and / or swells the toner.

  According to FIG. 8, the fixing liquid 29 that falls in the direction of the arrow 59 without contacting the toner image carrying surface 21 a is recovered as it is in the fixing liquid recovery tank 32. In order to bring the droplets of the fixing liquid 29 into contact with the toner image carrying surface 21a at a shallow angle, the fixing liquid 29 is discharged with a certain radiation angle, and the discharge width becomes larger as the distance from the non-contact applying device 28 increases. Become. As a result, although the amount of droplets falling without contacting the toner image carrying surface 21a increases, such droplets are recovered in the fixing liquid recovery tank 32, so that the fixing liquid 29 is consumed by the Further, the inside of the image forming apparatus 1 is not contaminated.

  In this way, the fixing liquid 29 is applied only to the image portion 21b of the toner image carrying surface 21a, and the consumption of the fixing liquid 29 can be minimized.

  The transfer fixing unit 6 includes a support roller 24 and a transfer fixing roller 35 that is in pressure contact with the support roller 24 via the intermediate transfer belt 21 and is rotatably driven in the axial direction. As the transfer fixing roller 35, for example, a roller having a silicon rubber layer having a thickness of 3 mm and a hardness (JIS-A) of 50 degrees on a surface of a core metal and a PFA layer having a thickness of 20 mm in this order is used. It is done. The transfer fixing roller 35 is disposed so as to press the intermediate transfer belt 21 and the support roller 24 with a linear pressure of 5 N / cm, for example, and no voltage is applied.

  The toner image on the intermediate transfer belt 21 to which the fixing liquid 29 is applied by the fixing liquid applying unit 4 and is in a softened and / or swollen state is pressed between the support roller 24 and the transfer fixing roller 35 by the rotation of the intermediate transfer belt 21. It is conveyed to the part. In synchronization with this, a recording medium 9 is fed from a recording medium supply means 7 described later, and the toner image on the intermediate transfer belt 21 is transferred onto the surface of the recording medium 9 by pressing and fixed.

  At this time, when the toner image carrying surface 21a of the intermediate transfer belt 21 is made of a fluororesin material having low adhesion to the toner, the entire amount of toner is transferred to the recording medium 9 with certainty.

  Further, when the intermediate transfer belt 21 has a configuration in which an elastic layer made of rubber or the like is interposed between the base material and the surface layer made of the fluororesin material, the surface layer is deformed following the irregularities on the surface of the recording medium 9. To do. As a result, the toner image can be brought into contact with the concave portion of the recording medium 9, and a uniform transfer-fixed image can be obtained.

  Further, when the recording medium 9 is paper, when the toner image is pressed against the recording medium 9, the toner particles strongly enter the paper fiber and at the same time, the toner particles are fused and transferred to the recording medium 9. The surface of the obtained image becomes uniform. As a result, a high-quality color image excellent in color developability and surface gloss by subtractive color mixing can be obtained.

  According to the transfer and fixing unit 6, the toner image in a softened and / or swollen state is transferred and fixed to the recording medium 9 by the fixing solution applying unit 4.

  The recording medium supply unit 7 transfers a recording medium cassette 36 that stores the recording medium 9, a pickup roller 37 that feeds the recording medium 9 one by one to the conveyance path P, and a multicolor toner image on the intermediate transfer belt 21. A pair of registration rollers 38 and 39 for feeding the recording medium 9 to the pressure contact portion in synchronization with being conveyed to the pressure contact portion between the fixing roller 35 and the support roller 24 is configured.

  According to the recording medium supply means 7, the recording medium 9 stored in the recording medium cassette 36 is fed to the conveyance path P one by one by the pickup roller 37, and further, the transfer fixing roller by the registration rollers 38 and 39. It is fed to the pressure contact portion between 35 and the support roller 24.

  The discharge unit 8 includes a conveyance belt 40, a drive roller 41, a tension roller 42, and a discharge roller 43.

  The conveyance belt 40 is an endless belt that is stretched between a driving roller 41 and a tension roller 42 to form a loop-shaped conveyance path. The recording medium 9 on which an image is formed by the transfer fixing unit 6 is discharged from the discharge roller. It is conveyed to 43. For the transport belt 40, for example, a polyimide film having a thickness of 100 μm to which a conductive agent has been added to provide conductivity, at least a recording medium transport surface 40a provided with a 10 μm thick coating layer made of PTFE can be used. .

  The driving roller 41 is provided so as to be rotatable around an axis by a driving unit (not shown). As the driving roller 41, for example, a hollow roller made of metal such as aluminum can be used.

  The tension roller 42 applies a predetermined tension to the conveyor belt 40 so that the conveyor belt 40 does not slack. The tension roller 42 includes, for example, a metal shaft body and a coating layer formed on the surface of the metal shaft body. Moreover, what consists only of metal shaft bodies may be sufficient. For example, stainless steel is used as the material of the metal shaft, and fluororubber is used as the material of the coating layer.

  The paper discharge roller 43 is a member that discharges the recording medium 9 conveyed by the conveyance belt 40 to a paper discharge tray 44 provided on the outer side surface of the image forming apparatus 1, and includes a pair of rollers provided so as to be in pressure contact with each other. Each roller is supported so as to be able to rotate in the respective axial directions.

  According to the image forming apparatus 1, the fixing liquid 29 is applied in a non-contact manner from the fixing liquid applying means 4 to the toner image formed on the intermediate transfer belt 21, which is a toner image carrier, by the toner image forming means 2. Then, the toner image is softened and / or swelled, and this is transferred and fixed onto the recording medium 9 by the transfer fixing means 6 to form an image. The fixing solution 29 that does not adhere to the intermediate transfer belt 21 is recovered by the fixing solution recovery means 5 and reused.

In the present embodiment, the fixer applying device 28 is used as the fixer applying unit 4, but the present invention is not limited to this, and the fixer applying device 60 shown in FIGS. 9 and 10 can be used. 9 and 10 are cross-sectional views schematically showing the configuration of the fixing liquid applying device 60. The fixing liquid applying device 60 is similar to the fixing liquid applying device 28, and corresponding portions are denoted by the same reference numerals and description thereof is omitted.
The fixing liquid applying device 60 includes shutter means 61 and 62.

  The shutter means 61 and 62 are provided so as to cover the nozzle array forming surface 51a of the ink jet head 50 and can be opened and closed by a driving means (not shown), so that the nozzle array 51 serving as a discharge port for the fixing liquid 29 is exposed to the atmosphere. This is a member for preventing the liquid component in the fixing solution 29 from evaporating and consuming the fixing solution 29 and further preventing the nozzle array 51 from being clogged due to the drying of the fixing solution 29.

  Further, the shutter units 61 and 62 have a moving unit (not shown) and can move in parallel with the nozzle array forming surface 51 a in a direction orthogonal to the longitudinal direction of the inkjet head 50. For example, the entire shutter means 61 and 62 can be translated with the opening 63 opened. Thus, when the fixing liquid 29 is discharged, the opening 63 formed by the shutter means 61 and 62 moves so that the position of the nozzle array 51 overlaps. On the other hand, when the fixing liquid 29 is not discharged, the opening 63 and the nozzle array 51 are moved. Move so that the positions of do not overlap. Further, without moving the shutter means 61, 62, the shutter means 61, 62 can be opened to form the opening 63 when discharging the fixing liquid 29, and the shutter means 61, 62 can be closed when not discharging.

  FIG. 11 is a cross-sectional view schematically showing a configuration of an image forming apparatus 65 according to the second embodiment of the present invention. The image forming apparatus 65 is similar to the image forming apparatus 1, and a part of the same portion is not shown and described. Also, of the illustrated portions, portions corresponding to the image forming apparatus 1 are denoted by the same reference numerals, and description thereof is omitted.

  The image forming apparatus 65 is characterized in that the fixing solution applying unit 4 a includes a fixing solution circulating unit 66 for circulating the fixing solution 29 collected in the fixing solution collecting tank 32 to the fixing solution reservoir 28 a of the fixing solution applying device 28. To do.

  The fixer circulation means 66 is provided in the middle of the fixer tube 67, one end of which is connected to the fixer recovery tank 32 and the other end is connected to the fixer reservoir 28 a and allows the fixer 29 to flow through. And a pumping pump 68 for feeding the fixing solution 29 of the fixing solution tube 67 in the direction of an arrow 69. According to the fixer circulation means 66, the fixer 29 recovered in the fixer recovery tank 32 is fed to the fixer reservoir 28 a of the fixer applying device 28 via the fixer tube 67 and reused.

  According to the image forming apparatus 65, the fixing liquid 29 is applied in a non-contact manner from the fixing liquid applying means 4 to the toner image formed on the intermediate transfer belt 21 which is a toner image carrier by the toner image forming means 2. Then, the toner image is softened and / or swelled, and this is transferred and fixed onto the recording medium 9 by the transfer fixing means 6 to form an image. The fixing solution 29 that does not adhere to the intermediate transfer belt 21 is returned from the fixing solution collecting unit 5 to the fixing solution applying unit 4 by the fixing solution circulating unit 67 and reused.

  FIG. 12 is a cross-sectional view schematically showing a configuration of an image forming apparatus 70 according to the third embodiment of the present invention. The image forming apparatus 70 is similar to the image forming apparatus 1, and a part of the same portion is not shown and described. Also, of the illustrated portions, portions corresponding to the image forming apparatus 1 are denoted by the same reference numerals, and description thereof is omitted.

  In the image forming apparatus 70, the fixing solution applying unit 72 and the fixing solution collecting unit 73 are arranged in one housing 71 so that the fixing solution collecting unit 73 is higher than the fixing solution applying unit 72. The casing 71 has an opening 74 for inserting the bent portion of the intermediate transfer belt 21 into the casing 71 and discharging the fixing solution 29 from the fixing liquid applying means 72 toward the bent portion. And

  The housing 71 faces the support roller 23 and has a side wall 71a having an opening 74 for inserting the bent portion of the intermediate transfer belt 21 into the housing 71, a side wall 71b facing the side wall 71a, and side walls 71a and 71b. It includes a top plate 71c supported so as to be inclined with respect to the bottom surface 71d. The side walls 71 a and 71 b also have an effect of preventing the fixing liquid 29 from scattering into the image forming apparatus 1. The opening 74 is formed to a size that does not hinder the rotational drive of the intermediate transfer belt 21.

  The fixing liquid applying unit 72 includes the fixing liquid applying device 28. The fixing liquid applying device 28 is an intermediate transfer in which a fixing liquid 29 discharged downward from a fixing liquid discharge port (nozzle array 51) (not shown) is inserted into the housing 71 below the support roller 23. The fixing liquid reservoir 28b is placed on the bottom 71d of the housing 71 so that the bent portion of the belt 21 is grabbed. At that time, a space 75 is provided between one side surface 28 x in the longitudinal direction of the fixing liquid applying device 28 and the side wall 71 b of the casing 71.

  The fixer recovery means 73 includes a top plate 71c that is a plate-like member. The top plate 71c is disposed with an inclination with respect to the horizontal plane so that the top plate 71c is positioned downward as it is separated from the side wall 71a. Therefore, the fixing liquid 29 bounced off by the intermediate transfer belt 21 and the fixing liquid 29 passing through the periphery of the belt 21 without adhering to the intermediate transfer belt 21 adhere to the top plate 71c, and this fixing liquid 29 is applied to the top plate 71c. The surface of the top plate 71c flows downward by the inclination and the own weight. The fixing liquid 29 is connected to the surface of the side wall 71b from the top plate 71c, flows through the surface of the side wall 71b to reach the space 75, and is stored in a fixing liquid reservoir by a fixing liquid storage means (not shown) provided on the side surface 28x of the fixing applying device 28. Returned to 28b. Examples of the fixing solution storage means include a rotary pump for supplying liquid. The fixing liquid reservoir 28b and a part of the space 75 are connected by the rotary pump, and the fixing liquid is transferred from the space 75 to the fixing liquid reservoir 28b.

  A part of the fixing liquid 29 discharged from the fixing liquid applying unit 72 toward the bent portion of the intermediate transfer belt 21 adheres to the toner image on the intermediate transfer belt 21 and softens and / or swells the toner. The fixing solution 29 that does not adhere to the intermediate transfer belt 21 adheres to the inner wall of the top plate 71c, flows along the inclination of the top plate 71c, and further travels along the surface of the side wall 71b and is stored in the space 75.

  According to the image forming apparatus 75, the toner image forming unit 2 does not contact the toner image formed on the intermediate transfer belt 21, which is a toner image carrier, from the fixing liquid applying unit 72 disposed below the toner image. A fixing solution 29 is applied below to soften and / or swell the toner image, which is transferred and fixed to the recording medium 9 by the transfer fixing means 6 to form an image. The fixing solution 29 that does not adhere to the intermediate transfer belt 21 is collected by a fixing solution collecting unit 73 disposed in the same casing 71 as the fixing solution applying unit 72.

  In this embodiment, the fixing liquid applying device 28 is used as the fixing liquid applying means 72, but the fixing liquid applying device 80 shown in FIGS. 13 and 14 can be used without being limited thereto. FIG. 13 is a perspective view showing the appearance of the main parts (first and second supply rollers 82 and 83 and metal mesh plate 85) of the fixing liquid applying device 80. FIG. FIG. 14 is a cross-sectional view schematically showing the configuration of the fixing liquid applying device 80 shown in FIG.

  The fixing liquid applying device 80 is a device that discharges fine droplets of the fixing liquid 29 to a toner image carried on the toner image carrying surface 21a in accordance with an electrical control signal. A supply roller 82, a second supply roller 83, a liquid amount regulating blade 84, a metal mesh plate 85, an ultrasonic transducer 86, and a power source 87 are configured.

  The fixing solution storage tank 81 stores the fixing solution 29. In the fixing solution storage tank 81, the fixing solution 29 is replenished and supplied by a fixing solution replenishing means (not shown) according to the consumption state of the fixing solution 29 so that the height of the fixing solution is always constant.

  A part of the first supply roller 82 is immersed in the fixing solution 29 of the fixing solution storage tank 61 and is provided so as to be rotationally driven in the direction of an arrow 88 by a driving means (not shown). By the rotation of the first supply roller 82, the fixing solution 29 adheres to the surface of the first supply roller 82, and this fixing solution 29 is supplied to the second supply roller 83.

  The second supply roller 83 is provided so as to be in pressure contact with the first supply roller 82 and the metal mesh plate 85 and to be rotationally driven in the direction of the arrow 89 by a driving means (not shown). The liquid amount regulating blade 84 is a plate-like member extending in the axial direction of the second supply roller 83, one end in the short direction abuts the surface of the second supply roller 83, and the other end in the short direction. It is provided so as to be fixed to the fixing liquid storage tank 81. Here, the second supply roller 83 and the liquid amount regulating blade 84 are provided to make the liquid amount of the fixing liquid 29 supplied to the metal mesh plate 85 constant. After the second supply roller 83 is supplied with the fixing liquid 29 at its surface in contact with the first supply roller 82, the liquid amount of the fixing liquid 29 on the surface is then adjusted by the liquid amount regulating blade 84. Then, the fixing liquid 29 is supplied to the metal mesh plate 85 by being pressed against the metal mesh plate 85.

  The metal mesh plate 81 is provided so as to extend in the rotation axis direction of the support roller 23, and is provided so that the ultrasonic transducer 86 is in contact with the surface opposite to the surface where the second supply roller 83 is in pressure contact. The ultrasonic transducer 86 is applied with a voltage from the power source 87 to generate an ultrasonic wave, and vibrates and expands and contracts. The metal mesh plate 81 vibrates in response to the vibration of the ultrasonic vibrator 86, and the fixing liquid 29 adhering to the surface of the second supply roller 83 is formed into droplets. The droplet 90 is converted into the toner image carrying surface of the intermediate transfer belt 21. Discharge toward 21a.

  According to the fixing liquid applying device 80, the fixing liquid 29 stored in the fixing liquid storage tank 81 is supplied to the metal mesh plate 85 via the first supply roller 82 and the second supply roller 83, and the metal mesh plate 85 is supplied. The liquid is vibrated by the ultrasonic vibrator 86, and the fixing liquid 29 is formed into droplets and discharged toward the toner image carrying surface 21a of the intermediate transfer belt 21. Such a fixing liquid application device 80 can also achieve the same effect as the fixing liquid application device 28.

  FIG. 15 is a cross-sectional view schematically showing a configuration of an image forming apparatus 91 according to the fourth embodiment of the present invention. The image forming apparatus 91 is similar to the image forming apparatus 70, and a part of the same portion is not shown and described. In addition, corresponding portions among the illustrated portions are denoted by the same reference numerals, and description thereof is omitted.

  In the image forming apparatus 91, the fixing liquid application device 28 is below the support roller 23, and the fixing liquid 29 discharged upward from a fixing liquid discharge port (nozzle array 51) (not shown) is installed in the housing 71. The fixing liquid reservoir 28b faces down to contact the bottom 71d of the casing 71 so that the bent portion of the intermediate transfer belt 21 is inserted, and one side surface 28x in the longitudinal direction and the side wall 71b of the casing 71 are placed. And a fixing liquid circulating means 92 for circulating and reusing the fixing liquid 29 collected by the fixing liquid collecting means 73 to the fixing liquid reservoir 28b of the fixing liquid applying device 28. To do.

  The fixing liquid applying device 28 constituting the fixing liquid applying means 72 is disposed such that the bottom surface of the fixing liquid reservoir 28 b is in contact with the bottom surface 71 d of the housing 71 and the side surface 28 x thereof is in contact with the side wall 71 b of the housing 71. Then, the fixing liquid 29 is discharged from the lower side toward the upper side so that the bent portion of the intermediate transfer belt 21 inserted into the housing 71 is squeezed.

  The fixer circulation means 92 prevents the fixer 29 from falling through the inner wall of the side wall 71b and the fixer circulation pipe 93 that circulates the fixer 29 recovered by the fixer recovery means 73 to the fixer reservoir 28b. And a fixing solution dropping prevention member 94 that is guided to the fixing solution circulation pipe 93.

  One end of the fixer circulation pipe 93 is connected to the fixer outlet 96 provided on the side wall 71b of the housing 71, and the other end is connected to the fixer inlet 97 provided in the fixer reservoir 28b portion of the side surface 28x. The fixer 29 flowing from the fluid outlet 96 is fed in the direction of the arrow 95 by natural fall and returned to the fixer reservoir 28b.

  The fixing solution dropping prevention member 94 is provided on the inner wall of the side wall 71b and directly below the fixing solution discharge port 96 so as to be inclined upwardly away from the side wall 71b. Fixing liquid 29 that adheres to the top plate 71 c and falls through the inner wall of the top plate 71 c and the side wall 71 c due to the inclination and dead weight of the top plate 71 c is received by the fixing solution fall-preventing member 94 from the fixing solution discharge port 96. It flows into the fixing liquid circulation pipe 93.

  According to the fixer circulation means 94, the fixer 29 adhering to the top plate 71c, which is the fixer recovery means 73, is received by the fixer drop prevention member 94, flows down the fixer circulation pipe 93, and the fixer reservoir 28b. Returned to

  According to the image forming apparatus 91, the toner image forming unit 2 does not contact the toner image formed on the intermediate transfer belt 21, which is a toner image carrier, from the fixing liquid applying unit 72 disposed below the toner image. A fixing solution 29 is applied below to soften and / or swell the toner image, which is transferred and fixed to the recording medium 9 by the transfer fixing means 6 to form an image. The fixing solution 29 that does not adhere to the intermediate transfer belt 21 is collected by a fixing solution collecting unit 73 disposed in the same casing 71 as the fixing solution applying unit 72, and the fixing solution applying unit 72 is passed through a fixing solution circulating unit 92. Returned to

  In the present embodiment, an integrated type in which the fixing liquid applying means 72 and the fixing liquid collecting means 73 are provided in the housing 71 is adopted, but a configuration in which the housing and the fixing applying means 72 are separate members may be employed. . In this case, for example, the housing is formed by the side walls 71a and 71b and the top plate 71c, and further has a length in a direction perpendicular to the longitudinal direction of the side wall 71b (a direction perpendicular to the paper surface). The fixing liquid applying device 28 can be shortened so as to be in contact with the upper surface of the fixing liquid discharge portion 28a.

  According to the image forming apparatus of each of the embodiments described above, the consumption amount of the fixing liquid 29 is reduced, and a high-quality fixed image can be obtained stably and for a long time.

  The image forming apparatus of the present invention can be used as, for example, a copying machine, a printer, a facsimile machine or the like. It can also be used as a multi-function machine having at least two functions of a copying function, a printer function, and a facsimile function.

1 is a cross-sectional view schematically showing a configuration of an image forming apparatus according to a first embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view illustrating a configuration of a main part of the image forming apparatus illustrated in FIG. 1. FIG. 2 is an enlarged cross-sectional view illustrating a configuration of a main part of the image forming apparatus illustrated in FIG. 1. FIG. 2 is a perspective view showing an external appearance of a fixing liquid applying device. FIG. 5 is a cross-sectional view schematically showing the configuration of the fixing liquid applying apparatus shown in FIG. 4. FIG. 3 is a perspective view illustrating an appearance of a main part of the fixing liquid applying device. FIG. 6 is a side view showing a state where a fixing liquid is applied to a non-image portion of a toner image carrying surface. FIG. 6 is a side view showing a state where a fixing liquid is applied to an image portion of a toner image carrying surface. FIG. 4 is a side view showing a state in which a fixing liquid passes through without being attached to a toner image carrying surface. 2 is a cross-sectional view schematically showing a configuration of a fixing liquid applying device. FIG. 2 is a cross-sectional view schematically showing a configuration of a fixing liquid applying device. FIG. It is sectional drawing which shows typically the structure of the image forming apparatus which is the 2nd Embodiment of this invention. It is sectional drawing which shows typically the structure of the image forming apparatus which is 3rd Embodiment of this invention. FIG. 3 is a perspective view illustrating an appearance of a main part of the fixing liquid applying device. It is sectional drawing which shows typically the structure of the fixing liquid provision apparatus shown in FIG. It is sectional drawing which shows typically the structure of the image forming apparatus which is 4th Embodiment of this invention.

Explanation of symbols

1, 65, 70, 91 Image forming apparatus 2 Toner image forming means 3 Intermediate transfer means 4, 4a, 72, 80 Fixing liquid applying means 5, 73 Fixing liquid collecting means 6 Transfer fixing means 7 Recording medium supply means 8 Ejecting means 9 Recording medium 10y, 10m, 10c, 10b Image forming unit 11y, 11m, 11c, 11b Photosensitive drum 12y, 12m, 12c, 12b Charging roller 13 Optical scanning unit 13y, 13m, 13c, 13b Signal light 14y, 14m, 14c, 14b Developing device 15y, 15m, 15c, 15b Drum cleaner 16y, 16m, 16c, 16b Toner 17y, 17m, 17c, 17b Developing roller 18y, 18m, 18c, 18b Developing blade 19y, 19m, 19c, 19b Toner storage container 20a, 20b Stirring roller 21 Intermediate transfer belt 1a Toner image carrying surface 21b Image portion 22y, 22m, 22c, 22b Intermediate transfer roller 23, 24, 25 Support roller 26 Belt cleaner 26a Cleaning blade 26b Toner storage container 27, 57, 58, 69, 88, 89, 95 28, 60 Fixing liquid applicator 28a Fixing liquid discharge part 28b Fixing liquid reservoir 28x Side surface 29 Fixing liquid 30 Fixing liquid storage tank 31 Fixing liquid supply pipe 32 Fixing liquid recovery tank 33, 63, 74 Opening 35 Transfer fixing roller 36 Recording medium Cassette 37 Pickup roller 38, 39 Registration roller 40 Conveying belt 41 Drive roller 42 Tension roller 43 Paper discharge roller 44 Paper discharge tray 50 Inkjet head 50a, 50b Side surface 51 Nozzle array 51a Nozzle array formation surface 51a
52 Chamber 53 Fixing liquid cartridge 54 Piezo element 55, 87 Power source 61, 62 Shutter means 66, 92 Fixing liquid circulation means 67 Fixing liquid tube 68 Pumping pump 71 Housing 71a, 71b Side wall 71c Top plate 71d Bottom surface 75 Space 81 Fixing liquid storage tank 82 First Supply Roller 83 Second Supply Roller 84 Liquid Level Control Blade 85 Metal Mesh Plate 86 Ultrasonic Vibrator 90 Droplet 93 Fixing Fluid Circulating Pipe 94 Fixing Solution Falling Prevention Member 96 Fixing Solution Discharge Port 97 Fixing Solution Receiving Port

Claims (12)

A toner image forming means for forming a toner image comprising a toner containing a binder resin and a colorant;
In a toner image carrier that carries and rotates a toner image formed by toner image forming means, at least the toner image carrier surface is made of a material that does not penetrate a fixing liquid that softens and / or swells the toner image. Body,
A fixing solution applying means for applying a fixing solution to the toner image on the toner image carrier in a non-contact manner;
A fixing liquid recovery means for recovering the fixing liquid that does not adhere to the toner image carrier in a non-contact manner with respect to the toner image carrier;
An image forming apparatus comprising: a transfer fixing unit that fixes a toner image to which a fixing liquid has been applied to a recording medium simultaneously with transfer. Fixing liquid application means
2. The image forming apparatus according to claim 1, wherein the fixing liquid is ejected substantially parallel to the toner image carrying surface of the toner image carrying body. Fixing liquid application means
3. The fixing liquid according to claim 1, wherein the fixing liquid is discharged to at least one of a plurality of support roller contact portions in a toner image carrier that is an endless belt that is rotatably stretched around the plurality of support rollers. Image forming apparatus. Fixing liquid application means
4. The image forming apparatus according to claim 2, further comprising a drying prevention means provided near the fixing liquid discharge port where the fixing liquid is exposed to the atmosphere, and prevents the liquid component in the fixing liquid from evaporating. . Drying prevention means
The image forming apparatus according to claim 4, wherein the image forming apparatus is a shutter unit that is openable and closable and that blocks the fixing liquid discharge port from the atmosphere. At least the toner image carrying surface of the toner image carrying body is
6. The image forming apparatus according to claim 1, wherein the image forming apparatus is made of a material having liquid repellency with respect to the fixing solution. Fixer recovery means
The image forming apparatus according to claim 1, further comprising a fixing solution circulating unit that circulates the collected fixing solution to a fixing solution applying unit. Fixer recovery means
The image forming apparatus according to claim 1, wherein the image forming apparatus is disposed at a position higher than the fixing solution applying unit. Fixer recovery means
A plate-shaped recovery member for collecting and recovering a fixing liquid that does not adhere to the toner image carrying surface of the toner image carrier among the fixing liquid ejected from the fixing liquid applying means, and is inclined with respect to the horizontal plane. The image forming apparatus according to claim 8, further comprising a collecting member provided in the manner described above. The fixing solution applying unit and the fixing solution collecting unit are housed in one casing.
The housing is for inserting at least a part of the toner image carrying surface of the toner image carrying body into the housing and discharging the fixing solution from the fixing solution discharge port of the fixing solution applying means toward the toner image carrying surface. The image forming apparatus according to claim 1, wherein the image forming apparatus has an opening.   The image forming apparatus according to claim 1, wherein the binder resin is a polyester resin.   The image forming apparatus according to claim 1, wherein the toner has a volume average particle diameter of 2 μm or more and 7 μm or less.

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