JP6115381B2 - Transfer member, transfer unit, image forming apparatus, and process cartridge - Google Patents

Description

  The present invention relates to a transfer member, a transfer unit, an image forming apparatus, and a process cartridge.

  For example, Patent Document 1 discloses that “an elastic roll formed of a core metal and an elastomer portion surrounding the core metal, and acicular barium titanate, acicular strontium titanate, or acicular titanium as a filler on the surface layer. An elastic roll composed of a silicon rubber elastomer containing barium strontium acid is disclosed.

  Patent Document 2 states that “a charging roll containing composite particles in which the outermost layer is coated with ferroelectric particles (strontium titanate, barium titanate) having a dielectric constant of 200 or more on the surface of mother particles (resin particles). Is disclosed.

JP 09-277403 A JP 2005-316263 A

  An object of the present invention is to provide a transfer member that provides a transfer member that suppresses occurrence of white spots in an image even when the size of a recording medium is changed.

  The above problem is solved by the following means.

The invention according to claim 1
A transfer member comprising an elastic material and an elastic layer having an Asker C hardness of more than 60 ° as measured from the surface of the elastic layer, including a piezoelectric material having an average particle diameter of 60 μm or more whose volume increases by application of voltage.

The invention according to claim 2
The transfer member according to claim 1, wherein the elastic material is an elastic material excluding silicone rubber.

The invention according to claim 3
The transfer member according to claim 1 or 2,
A facing member disposed to face the transfer member;
With
When passing between the opposing member and the transfer member, a transfer unit wherein the transfer member said to impart an electric field between the counter member and transfers the toner image on the record medium.

The invention according to claim 4
The transfer unit according to claim 3, wherein the Asker C hardness measured from the surface of the facing member is 50 ° or more.

The invention according to claim 5
An image forming apparatus comprising the transfer unit according to claim 3 .

The invention according to claim 6
An image carrier,
Charging means for charging the image carrier;
An electrostatic charge image forming means for forming an electrostatic charge image on the surface of the charged image carrier;
Developing means for developing, as a toner image, an electrostatic charge image formed on the image carrier with an electrostatic charge image developer containing toner;
An intermediate transfer member to which the toner image formed on the surface of the image carrier is transferred;
Primary transfer means for primarily transferring the toner image formed on the surface of the image carrier to the surface of the intermediate transfer member;
3. A secondary transfer unit that secondary-transfers the toner image transferred to the surface of the intermediate transfer member to a recording medium, and is disposed outside the intermediate transfer member, and the transfer member according to claim 1. , anda facing member disposed to face the transfer member to the inside of the intermediate transfer body, passing between the said opposing member, wherein the recording medium via the intermediate transfer member and the transfer member A secondary transfer unit that applies an electric field between the transfer member and the opposing member to secondarily transfer the toner image to the recording medium;
Fixing means for fixing the toner image transferred to the recording medium;
An image forming apparatus.

The invention according to claim 7 provides:
An image carrier,
Charging means for charging the image carrier;
An electrostatic charge image forming means for forming an electrostatic charge image on the surface of the charged image carrier;
Developing means for developing, as a toner image, an electrostatic charge image formed on the image carrier with an electrostatic charge image developer containing toner;
Transfer means for transferring a toner image formed on the image holding body onto a recording medium, the transfer means being provided facing the image holding body, comprising the transfer member according to claim 1, A transfer unit that applies an electric field between the transfer member and the image carrier when the recording medium passes between the transfer member and the image carrier, and transfers the toner image to the recording medium; ,
Fixing means for fixing the toner image transferred onto the recording medium;
An image forming apparatus comprising:

  According to the first aspect of the present invention, even when the size of the recording medium is changed, the occurrence of white spots in the image is reduced as compared with the case where the piezoelectric material is not included and the elastic layer has an Asker C hardness exceeding 60 °. A suppressed transfer member is provided.

  According to the invention which concerns on Claim 2, the transfer roll of Claim 1 which has an elastic layer except silicone rubber is provided.

According to the third aspect of the present invention, even when the size of the recording medium is changed as compared with the case of including a transfer member that does not include a piezoelectric material and has an elastic layer having an Asker C hardness exceeding 60 °, A transfer unit that suppresses occurrence of omission is provided.
According to the fourth aspect of the present invention, there is provided a transfer unit that suppresses the occurrence of white spots in the image even when the size of the recording medium is changed as compared with the case where the opposing member having a surface Asker C hardness of less than 50 ° is provided. Provided.

  According to the fifth aspect of the present invention, even when the size of the recording medium is changed as compared with the case of including a transfer member that does not include a piezoelectric material and has an elastic layer having an Asker C hardness exceeding 60 °, the whiteness of the image is increased. An image forming apparatus that suppresses occurrence of omission is provided.

  According to the sixth aspect of the present invention, even when the size of the recording medium is changed as compared with the case where a transfer member having an elastic layer that does not include a piezoelectric material and has an Asker C hardness exceeding 60 ° is provided, the whiteness of the image is increased. An intermediate transfer type image forming apparatus that suppresses occurrence of omission is provided.

  According to the seventh aspect of the present invention, even when the size of the recording medium is changed as compared with the case where a transfer member having an elastic layer that does not include a piezoelectric material and has an Asker C hardness exceeding 60 ° is provided. An image forming apparatus of a direct transfer system that suppresses occurrence of omission is provided.

It is a side view which shows the transfer unit which concerns on 1st Embodiment. It is a schematic diagram for demonstrating the mechanism in which generation | occurrence | production of the white spot of an image generate | occur | produces. FIG. 6 is a schematic diagram for explaining that occurrence of white spots in an image is suppressed in the transfer unit according to the first embodiment. It is a side view which shows the transfer unit which concerns on 2nd Embodiment. It is a schematic block diagram which shows the image forming apparatus which concerns on 3rd Embodiment. It is a schematic block diagram which shows the image forming apparatus which concerns on 4th Embodiment.

  Hereinafter, an embodiment which is an example of the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 is a side view showing a transfer unit according to the first embodiment.

  As shown in FIG. 1, the transfer unit 101 according to the first embodiment is, for example, a transfer unit that forms a secondary transfer unit, and is disposed outside the intermediate transfer belt 20 (an example of an intermediate transfer member). A secondary transfer roll 26 (an example of a transfer member), and a back roll 24 (an example of an opposing member) that is disposed inside the intermediate transfer belt 20 and is opposed to the secondary transfer roll 26.

  For example, the secondary transfer roll 26 includes a support 26A and an elastic layer 26B provided on the support 26A. The elastic layer 26B includes an elastic material and a piezoelectric material whose volume is increased by application of voltage, and the Asker C hardness measured from the surface exceeds 60 °.

  On the other hand, the back roll 24 includes, for example, a support 24A and an elastic layer 24B provided on the support 24A. Here, as for the back roll 24, it is good that Asker C hardness measured from the surface is 50 degrees or more.

  In the transfer unit 101 according to this embodiment, the recording paper P (an example of a recording medium) passes between the secondary transfer roll 26 and the back roll 24 via the intermediate transfer belt 20 while being in contact with the secondary transfer roll 26. In this case, an electric field (hereinafter referred to as “transfer electric field”) is applied between the secondary transfer roll 26 and the back roll 24 to transfer the toner image T formed on the intermediate transfer belt 20 to the recording paper P. (See FIG. 2A). That is, when the recording paper P passes between the secondary transfer roll 26 and the intermediate transfer belt 20 and the area where the secondary transfer roll 26 and the back roll 24 face each other, the recording paper P is placed on the intermediate transfer belt 20. The toner image T formed on the toner is transferred.

  Here, in the secondary transfer portion, the recording paper P enters the contact portion (hereinafter referred to as “nip portion”) between the secondary transfer roll 26 and the back roll 24 via the intermediate transfer belt 20, and the intermediate transfer belt 20. When the toner image T formed on the image is transferred, an area through which the recording paper P passes (hereinafter referred to as “sheet passing portion”) and an area through which the recording paper P does not pass (hereinafter referred to as “non-sheet passing portion”) are formed. In this non-sheet passing portion, since the recording P does not pass, a gap (denoted by G in FIG. 2) is generated between the secondary transfer roll 26 and the intermediate transfer belt 20.

  In this state, when a transfer electric field is applied between the secondary transfer roll 26 and the back roll 24 in order to perform the transfer, that is, when a voltage is applied, the recording paper P in the non-sheet passing portion is compared with the sheet passing portion. Therefore, the system resistance between the secondary transfer roll 26 and the intermediate transfer belt 20 is reduced by the recording paper P, and a voltage (electric field) applied between the secondary transfer roll 26 and the intermediate transfer belt 20 is reduced. Rise. For this reason, discharge (hereinafter referred to as “gap discharge”) may occur in the gap generated in the non-sheet passing portion.

  In particular, when a secondary transfer roll 26 having a high Asker C hardness of more than 60 ° is applied, when the recording paper P passes between the secondary transfer roll 26 and the intermediate transfer belt 20, Crushing due to elastic deformation of the elastic layer 26 </ b> B hardly occurs in the paper portion, the gap generated in the non-paper passing portion is maintained, and a gap discharge is likely to occur.

  When the gap discharge occurs, the dielectric breakdown of the elastic layer 26B of the secondary transfer roll 26 serving as a non-sheet passing portion occurs, and the electrical resistance of the elastic layer 26B decreases. As a result, the electric resistance of the elastic layer 26B necessary for applying the transfer electric field is not maintained. A similar phenomenon occurs in the intermediate transfer belt 20.

  Then, after the dielectric breakdown occurs due to the gap discharge, the recording paper P (the recording paper P in which the axial length of the secondary transfer roll 26 is large) is larger than the recording paper P when the gap discharge is generated. When the transfer is performed (see FIG. 2B), the area of the sheet passing portion of the recording paper P is widened, and the transfer is performed even in the area where the dielectric breakdown of the intermediate transfer belt 20 and the elastic layer 26B of the secondary transfer roll 26 occurs. Will be done. In a region where the dielectric breakdown of the intermediate transfer belt 20 and the elastic layer 26B of the secondary transfer roll 26 occurs, the necessary electric train electric field is not applied, and the transfer of the toner image T may occur in that region. For this reason, when the size of the recording paper P is changed, white spots of the image may occur.

  On the other hand, in the transfer unit 101 according to the present embodiment, if the elastic layer 26B of the secondary transfer roll 26 includes a piezoelectric material whose volume is increased by application of voltage, the secondary transfer roll 26 and the intermediate transfer belt 20 are included. When a voltage for applying a transfer electric field is applied to the piezoelectric material, a voltage is also applied to the piezoelectric material. In the non-sheet passing portion, the voltage applied between the secondary transfer roll 26 and the intermediate transfer belt 20 is compared with the sheet passing portion due to the gap generated between the secondary transfer roll 26 and the back roll 24. Since it increases, the voltage applied to the piezoelectric material of the elastic layer 26B also increases. By applying this increased voltage, the volume of the piezoelectric material of the elastic layer 26B in the non-sheet passing portion increases. When the volume of the piezoelectric material increases, the surface (outer peripheral surface) of the elastic layer 26B in the non-sheet passing portion rises, and there is no gap between the secondary transfer roll 26 and the intermediate transfer belt 20, or the gap interval generated therebetween. Is narrowed (see FIG. 3).

  As a result, the occurrence of cap discharge at the non-sheet passing portion is suppressed, and the dielectric breakdown of the intermediate transfer belt 20 and the elastic layer 26B of the secondary transfer roll 26 is suppressed. For this reason, after the transfer is performed on the recording paper P having a certain paper size, the recording paper P having a paper size larger than the recording paper P (the recording paper P having a large axial length of the secondary transfer roll 26). Even if the transfer is performed, occurrence of transfer failure of the toner image T is suppressed.

  As described above, in the transfer unit 101 according to the present embodiment, even if the size of the recording paper P is changed, the occurrence of white spots in the image is suppressed.

In particular, when the Asker C hardness measured from the surface of the back roll 24 facing the secondary transfer roll 26 is 50 ° or higher (preferably 60 ° C. or higher, more preferably 65 ° or higher) and high hardness, the recording paper P is second. When passing between the next transfer roll 26 and the intermediate transfer belt 20, the elastic layer 24 </ b> B of the back roll 24 is hardly crushed due to elastic deformation at the sheet passing portion, and the gap generated at the non-sheet passing portion is maintained, and gap discharge is performed. Is likely to occur. However, in the transfer unit 101 according to the present embodiment, even if the Asker C hardness measured from the surface of the back roll 24 facing the secondary transfer roll 26 is 50 ° or more, the size of the recording paper P can be changed. The occurrence of white spots in the image is suppressed.
However, the upper limit of the Asker C hardness of the back roll 24 is preferably 75 ° or less, and preferably 70 ° or less in order to ensure the transfer nip width.

  Details of each member will be described below.

(Secondary transfer roll)
For example, the secondary transfer roll 26 includes a support 26A and an elastic layer 26B provided on the support 26A. If necessary, the secondary transfer roll 26 may have a surface resin layer provided on the elastic layer 26B.

-Support-
The support 26 </ b> A is a conductive member that functions as an electrode and a support member for the secondary transfer roll 26.
Examples of the support 26A include metal members such as iron (free-cutting steel, etc.), copper, brass, stainless steel, aluminum, nickel, and the like.
Examples of the support 26A include a member (for example, a resin or a ceramic member) whose outer surface is plated, a member in which a conductive agent is dispersed (for example, a resin or a ceramic member), and the like.
The support 26A may be a hollow member (cylindrical member) or a non-hollow member.

-Elastic layer-
The Asker C hardness of the elastic layer 26B exceeds 60 ° C., preferably 70 ° or more, more preferably 75 ° or more. The upper limit of Asker C hardness of the secondary transfer roll 26 is preferably 90 ° or less, and preferably 85 ° or less, in order to ensure the transfer nip width.

  Here, the Asker C hardness is the state where the elastic layer 26B is provided on the support 26A, and the Asker C-type hardness meter (trade name “Asker rubber hardness meter C1L type (manufactured by Kobunshi Keiki Co., Ltd.)) on the surface of the elastic layer. ")" Is a value measured under the condition of a load of 1000 g by pressing the measuring needle.

  The elastic layer 26B is a conductive layer, and includes an elastic material (rubber material) and a piezoelectric material whose volume is increased by application of a voltage. In addition to the elastic material and the piezoelectric material, the elastic layer 26B may include a conductive agent and other additives. The elastic layer 26B may be a conductive foamed elastic layer or a conductive non-foamed elastic layer. However, when a surface resin layer is provided, the viewpoint of preventing the coating liquid from entering the elastic layer when the surface resin layer is formed. To non-foamed elastic layers are preferred.

Examples of the elastic material (rubber material) include an elastic material having a double bond in at least a chemical structure.
Specific examples of the elastic material include isoprene rubber, chloroprene rubber, epichlorohydrin rubber, butyl rubber, polyurethane, silicone rubber, fluorine rubber, styrene-butadiene rubber, butadiene rubber, nitrile rubber, ethylene propylene rubber, epichlorohydrin-ethylene oxide copolymer rubber. , Epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer rubber, ethylene-propylene-diene terpolymer rubber (EPDM), acrylonitrile-butadiene copolymer rubber (NBR), natural rubber, and rubbers obtained by mixing these.
In particular, the elastic material is preferably an elastic material excluding silicone rubber because the Asker C hardness of the elastic layer is within the above range. Among these elastic materials, polyurethane, EPDM, epichlorohydrin-ethylene oxide copolymer rubber, epichlorohydrin are preferred. -An ethylene oxide-allyl glycidyl ether copolymer rubber, NBR, and the rubber which mixed these are mentioned suitably.

A piezoelectric material is a piezoelectric material whose volume increases upon application of a voltage. Specifically, the piezoelectric material may be a piezoelectric material having a piezoelectric strain constant of 285 pC / N or more (preferably 300 pC / N or more).
The piezoelectric strain constant is the amount of strain generated when a unit electric field is applied in a state of zero stress (a state in which no stress is applied).

  Examples of the piezoelectric material having this characteristic include granular materials such as an inorganic piezoelectric material and an organic piezoelectric material. Moreover, as a piezoelectric material, the granular material of the composite piezoelectric material of an inorganic piezoelectric material and an organic piezoelectric material may be sufficient.

Examples of the particulate ceramic piezoelectric material include lead zirconate titanate (Pb [Zr · Ti] O ₃ : PZT), barium titanate (BaTiO ₃ ), strontium titanate (SrTiO ₃ ), and barium strontium titanate ( [Ba · Sr] TiO ₃ ), lead titanate (PbTiO ₃ ), lead niobate (PbNb ₂ O ₆ ), lithium niobate (LiNbO ₃ ), lithium tantalate (LiTaO ₃ ), bismuth germanate (Bi ₁₂ GeO ₂₀ )
Well-known piezoelectric materials such as gallium phosphate (GaPO ₄ ) and quartz can be cited.
Examples of the granular material of the polymeric piezoelectric material include granular materials of a known piezoelectric material such as polyvinylidene fluoride (PVDF), a copolymer of polyvinylidene fluoride (PVDF), and polyurea.
Among these, as the piezoelectric material, lead zirconate titanate (PZT) is preferable from the viewpoint of suppressing gap discharge.
A piezoelectric material may be used independently and may be used in combination of 2 or more type.

  The shape of the piezoelectric material may be any shape such as a spherical shape, an indefinite shape, a cubic shape, a plate shape, a column shape, or a needle shape, but a plate shape or a needle shape is preferable from the viewpoint of suppressing gap discharge.

The average particle size of the piezoelectric material is, for example, preferably 60 μm or more, preferably 150 μm or more, more preferably 500 μm or more.
Here, the average particle diameter is obtained by observing with an electron microscope a sample obtained by cutting an elastic layer containing a piezoelectric material, and measuring and averaging 100 diameters (maximum diameters) of the granular material of the piezoelectric material. Calculated by

  The content of the piezoelectric material is, for example, preferably in the range of 40 parts by mass to 65 parts by mass with respect to 100 parts by mass of the elastic material, preferably 45 parts by mass to 60 parts by mass, and more preferably 50 parts by mass or more. 55 parts by mass or less. If the content of the piezoelectric material is 70 parts by mass or more with respect to 100 parts by mass of the elastic material, it is easy to cause molding failure of the elastic layer, which is not preferable.

  The conductive agent is used when the elasticity of the elastic material is low or when the elastic material does not have conductivity. Examples of the conductive agent include an electronic conductive agent and an ionic conductive agent.

Examples of the electronic conductive agent include carbon black such as ketjen black and acetylene black; pyrolytic carbon, graphite; various conductive metals or alloys such as aluminum, copper, nickel, and stainless steel; tin oxide, indium oxide, and titanium oxide. And various conductive metal oxides such as tin oxide-antimony oxide solid solution, tin oxide-indium oxide solid solution; and the like.
Here, specific examples of carbon black include “Special Black 350”, “Special Black 100”, “Special Black 250”, “Special Black 5”, “Special Black 4”, “Special Black 4A”, “Special Black 550”, “Special Black 6”, “Color Black FW200”, “Color Black FW2”, “Color Black FW2V”, “MONARCH1000” manufactured by Cabot, Cabot “MONARCH1300” manufactured by Cabot Corporation, “MONARCH1400” manufactured by Cabot Corporation, “MOGUL-L”, “REGAL400R”, etc.
An electronic conductive agent may be used independently and may be used in combination of 2 or more type.
The content of the electronic conductive agent may be, for example, from 1 part by mass to 30 parts by mass, and preferably from 15 parts by mass to 25 parts by mass with respect to 100 parts by mass of the elastic material.

Examples of the ionic conductive agent include quaternary ammonium salts (for example, lauryltrimethylammonium, stearyltrimethylammonium, octadodecyltrimethylammonium, dodecyltrimethylammonium, hexadecyltrimethylammonium, perchlorates such as modified fatty acid and dimethylethylammonium urine, Chlorates, borofluorides, sulfates, etosulphate salts, benzyl halide salts (eg, benzyl bromide salts, benzyl chloride salts, etc.), aliphatic sulfonates, higher alcohol sulfates, higher Alcohol ethylene oxide addition sulfate ester salt, higher alcohol phosphate ester salt, higher alcohol ethylene oxide addition phosphate ester salt, various betaines, higher alcohol ethylene oxide, polyethylene glycol Fatty acid esters, polyhydric alcohol fatty acid esters.
An ionic conductive agent may be used independently and may be used in combination of 2 or more type.
The content of the ionic conductive agent is, for example, preferably in the range of 0.1 parts by mass or more and 5.0 parts by mass or less, preferably 0.5 parts by mass or more and 3.0 parts by mass with respect to 100 parts by mass of the elastic material. It is below mass parts.

  Other additives include, for example, foaming agents, foaming aids, softeners, plasticizers, curing agents, vulcanizing agents, vulcanization accelerators, antioxidants, surfactants, coupling agents, fillers (silica , Calcium carbonate, etc.), which can be added to the elastic layer.

  The thickness of the elastic layer 26B is, for example, 5 mm or more and 20 mm or less, and preferably 5 mm or more and 15 mm or less.

-Surface resin layer-
The surface resin layer is a layer provided on the elastic layer 26B as necessary.
The surface resin layer includes, for example, a resin material and a conductive agent, and may also include other additives.

Resin materials include acrylic resin, cellulose resin, polyamide resin, copolymerized nylon, polyurethane resin, polycarbonate resin, polyester resin, polyethylene resin, polyvinyl resin, polyarylate resin, styrene butadiene resin, melamine resin, epoxy resin, urethane resin, Examples thereof include silicone resins, fluororesins (for example, tetrafluoroethylene perfluoroalkyl vinyl ether copolymers, tetrafluoroethylene-hexafluoropropylene copolymers, polyvinylidene fluoride, etc.), urea resins, and the like. Further, the resin material may be one obtained by curing a curable resin with a curing agent.
Here, the copolymer nylon includes one or more of 610 nylon, 11 nylon, and 12 nylon as polymerized units, and other polymer units included in the copolymer include , 6 nylon, 66 nylon and the like.

  Examples of the conductive agent include an electronic conductive agent and an ionic conductive agent. Examples of these conductive agents include the same conductive agents as described in the elastic layer 26B.

  Examples of other additives include materials that can be added to a normal resin layer such as a plasticizer, a curing agent, a softening agent, an antioxidant, and a surfactant.

  In addition to reaction inhibitors, metal catalysts, surfactants, foam stabilizers, defoamers, flame retardants, plasticizers, pigments, dyes, stabilizers, antibacterial agents, fillers, etc. for the surface resin layer Additives for may be included.

The surface resin layer is formed by preparing a coating solution by dispersing each component in a solvent, applying the coating solution on the elastic layer, drying, and baking (curing) as necessary.
Here, for preparing the coating liquid, it is preferable to use a collision type disperser such as a jet mill or a homogenizer from the viewpoint of enhancing the dispersibility of the conductive agent (carbon black). By increasing the dispersibility of the conductive agent (carbon black), the content of the conductive agent in the surface resin layer is increased and the microhardness is increased while suppressing an excessive increase in the resistivity of the surface resin layer.

  The thickness of the surface resin layer is, for example, preferably 5 μm or more and 40 μm or less, and preferably 10 μm or more and 30 μm or less.

(Back roll)
The back roll 24 includes, for example, a support 24A and an elastic layer 24B provided on the support 24A. Examples of the support 24A and the elastic layer 24B include the same configurations as the support 26A and the elastic layer 26B of the secondary transfer roll 26. However, the elastic layer 24B does not include a piezoelectric material.

  In the transfer unit 101 according to the first embodiment described above, the embodiment in which the roll member (secondary transfer roll 26) is applied as an example of the transfer member has been described. However, the transfer member is a belt member. There may be. In this embodiment, the belt member may be, for example, a transfer belt having a two-layer structure in which an elastic layer and a surface resin layer are sequentially stacked, or three layers in which a base layer, an elastic layer, and a surface resin layer are sequentially stacked. A transfer belt having a configuration may be used.

[Second Embodiment]
FIG. 4 is a side view showing the transfer unit according to the second embodiment.
The transfer unit 102 according to the present embodiment is a transfer unit that constitutes a primary transfer unit. For example, as illustrated in FIG. 4, the photoconductor (an example of an opposing member and an image holding body) 1 and the photoconductor 1 are opposed to each other. And a primary transfer roll 5 (an example of a transfer member) disposed.

The photoreceptor 1 may be either an inorganic photoreceptor or an organic photoreceptor.
On the other hand, the primary transfer roll 5 includes, for example, a support 5A and an elastic layer 5B provided on the support 5A. The elastic layer 5B includes an elastic material and a piezoelectric material whose volume increases when a voltage is applied, and the Asker C hardness measured from the surface exceeds 60 °. The support 5A and the elastic layer 5B of the primary transfer roll 5 have the same configuration as the support 26A and the elastic layer 26B of the secondary transfer roll 26 described in the first embodiment. Further, the primary transfer roll 5 may be provided with a surface resin layer on the elastic layer 5B as necessary, similarly to the secondary transfer roll 26 described in the first embodiment.

  In the transfer unit 102 according to this embodiment, when the recording paper P (an example of a recording medium) passes between the primary transfer roll 5 and the photoreceptor 1 while being in contact with the primary transfer roll, the primary transfer roll 5 and the photoreceptor. The toner image T formed on the photosensitive member 1 is transferred onto the recording paper P by applying an electric field between the toner 1 and the recording paper P.

  In the transfer unit 102 according to the present embodiment, the elastic material 5B and the elastic layer 5B of the primary transfer roll 5 with the Asker C hardness measured from the surface of the elastic layer 5B exceeding 60 ° are used, as in the first embodiment. By including the piezoelectric material whose volume is increased by the application of voltage, the occurrence of white spots in the image is suppressed even when the size of the recording paper P is changed.

  In particular, if the photosensitive member 1 has a well-known configuration, the Asker C hardness is basically a high hardness of 50 ° or more. For this reason, when the recording paper P passes between the primary transfer roll 5 and the photoconductor 1, the photoconductor 1 is hardly crushed in the paper passing portion, the gap generated in the non-paper passing portion is maintained, and the gap discharge is generated. It is easy to occur. However, even in the case of a direct transfer type transfer unit such as the transfer unit 102 according to the present embodiment, the occurrence of white spots in the image is suppressed even if the size of the recording paper P is changed.

  In the transfer unit 102 according to the second embodiment described above, the form in which the roll member (primary transfer roll 5) is applied as an example of the transfer member has been described. However, the present invention is not limited to this, and the transfer member is a belt member. May be. In this embodiment, the belt member may be, for example, a transfer belt having a two-layer structure in which an elastic layer and a surface resin layer are sequentially stacked, or three layers in which a base layer, an elastic layer, and a surface resin layer are sequentially stacked. A transfer belt having a configuration may be used.

[Third Embodiment]
FIG. 5 is a schematic configuration diagram illustrating an image forming apparatus according to the third embodiment.
The image forming apparatus according to the third embodiment is an intermediate transfer type apparatus including the transfer unit according to the first embodiment as a secondary transfer unit.

Specifically, the image forming apparatus according to the third embodiment, as shown in FIG. 5, for example, yellow (Y), magenta (M), cyan (C), black (based on color-separated image data) K) first to fourth image forming units 10Y, 10M, 10C, and 10K (an example of image forming means) that output images of respective colors. These image forming units (hereinafter sometimes simply referred to as “units”) 10Y, 10M, 10C, and 10K are arranged in parallel at a predetermined distance from each other in the horizontal direction.
The units 10Y, 10M, 10C, and 10K may be process cartridges that are detachable from the image forming apparatus.

Above each of the units 10Y, 10M, 10C, and 10K, an intermediate transfer belt 20 (an example of an intermediate transfer member) is provided to extend through each unit. The intermediate transfer belt 20 is provided by being wound around a driving roller 22 and a back roll 24 that is in contact with the inner surface of the intermediate transfer belt 20 that are spaced apart from each other from the left to the right in the drawing. The vehicle travels in the direction toward the unit 10K. The back roll 24 is applied with a force in a direction away from the drive roller 22 by a spring or the like (not shown), and tension is applied to the intermediate transfer belt 20 wound around both. An intermediate transfer member cleaning device 30 is provided on the outer peripheral surface of the intermediate transfer belt 20 so as to face the drive roller 22.
Each of the developing devices 4Y, 4M, 4C, and 4K of the units 10Y, 10M, 10C, and 10K has four colors of yellow, magenta, cyan, and black contained in the toner cartridges 8Y, 8M, 8C, and 8K. Toner is supplied.

  Since the first to fourth units 10Y, 10M, 10C, and 10K described above have the same configuration, here, the first image that forms the yellow image disposed on the upstream side in the intermediate transfer belt traveling direction is formed. The unit 10Y will be described as a representative. It should be noted that reference numerals with magenta (M), cyan (C), and black (K) are attached to the same parts as those of the first unit 10Y instead of yellow (Y). Description of the units 10M, 10C, and 10K will be omitted.

The first unit 10Y has a photoreceptor 1Y (an example of an image holding member). Around the photoreceptor 1Y, a charging device 2Y (for example, a charging roll: an example of a developing unit) that charges the surface of the photoreceptor 1Y to a predetermined potential, a laser based on an image signal obtained by color-separating the charged surface. An exposure device 3 (an example of an electrostatic image forming unit) that forms an electrostatic image by exposure with light rays 3Y, and a developing device 4Y (an example of a developing unit) that supplies toner charged to the electrostatic image to develop the electrostatic image. ), A primary transfer roll 5Y (an example of a primary transfer unit) that transfers the developed toner image onto the intermediate transfer belt 20, and a photoreceptor cleaning device 6Y (cleaning) that removes toner remaining on the surface of the photoreceptor 1Y after the primary transfer. An example of means) is arranged in order.
The primary transfer roll 5Y is disposed inside the intermediate transfer belt 20, and is provided at a position facing the photoreceptor 1Y. Further, a bias power source (not shown) for applying a primary transfer bias is connected to each of the primary transfer rolls 5Y, 5M, 5C, and 5K. Each bias power source varies the transfer bias applied to each primary transfer roll under the control of a control unit (not shown).

Hereinafter, an operation of forming a yellow image in the first unit 10Y will be described. First, prior to the operation, the surface of the photoreceptor 1Y is charged to a potential of about −600V to −800V by the charging device 2Y.
The photoreceptor 1Y is formed by laminating a photosensitive layer on a conductive substrate (volume resistivity at 20 ° C .: 1 × 10 ⁻⁶ Ωcm or less). This photosensitive layer usually has a high resistance (a resistance equivalent to that of a general resin), but has a property that the specific resistance of the portion irradiated with the laser beam changes when irradiated with the laser beam 3Y. Therefore, a laser beam 3Y is output to the surface of the charged photoreceptor 1Y via the exposure device 3 in accordance with yellow image data sent from a control unit (not shown). The laser beam 3Y is applied to the photosensitive layer on the surface of the photoreceptor 1Y, whereby an electrostatic charge image of a yellow print pattern is formed on the surface of the photoreceptor 1Y.

The electrostatic charge image is an image formed on the surface of the photoreceptor 1Y by charging, and the specific resistance of the irradiated portion of the photosensitive layer is lowered by the laser beam 3Y, and the charged charge on the surface of the photoreceptor 1Y flows. On the other hand, this is a so-called negative latent image formed by the charge remaining in the portion not irradiated with the laser beam 3Y.
The electrostatic charge image formed on the photoreceptor 1Y in this way is rotated to a predetermined development position as the photoreceptor 1Y travels. At this development position, the electrostatic charge image on the photoreceptor 1Y is visualized (developed image) by the developing device 4Y.

  In the developing device 4Y, for example, an electrostatic charge image developer containing at least yellow toner and a carrier is accommodated. The yellow toner is triboelectrically charged by being agitated inside the developing device 4Y, and has a charge of the same polarity (negative polarity) as the charged charge on the photoreceptor 1Y, and a developer roll (developer holder). Is held on. As the surface of the photoreceptor 1Y passes through the developing device 4Y, the yellow toner is electrostatically attached to the latent image portion on the surface of the photoreceptor 1Y, and the latent image is developed with the yellow toner. . The photoreceptor 1Y on which the yellow toner image is formed continues to run at a predetermined speed, and the toner image developed on the photoreceptor 1Y is conveyed to a predetermined primary transfer unit.

When the yellow toner image on the photoreceptor 1Y is conveyed to the primary transfer, a primary transfer bias is applied to the primary transfer roll 5Y, and an electrostatic force from the photoreceptor 1Y toward the primary transfer roll 5Y is applied to the toner image, so that the photoreceptor is exposed. The toner image on 1Y is transferred onto the intermediate transfer belt 20. The transfer bias applied at this time has a (+) polarity opposite to the polarity (−) of the toner. For example, in the first unit 10Y, it is controlled to about +10 μA by the control unit (not shown).
On the other hand, the toner remaining on the photoreceptor 1Y is removed and collected by the cleaning device 6Y.

Further, the primary transfer bias applied to the primary transfer rolls 5M, 5C, and 5K after the second unit 10M is also controlled in accordance with the first unit.
Thus, the intermediate transfer belt 20 onto which the yellow toner image has been transferred by the first unit 10Y is sequentially conveyed through the second to fourth units 10M, 10C, and 10K, and the toner images of the respective colors are superimposed and transferred in a multiple manner. The

The intermediate transfer belt 20 onto which the four color toner images have been transferred through the first to fourth units is arranged on the image transfer surface side of the intermediate transfer belt 20, the rear roll 24 in contact with the inner surface of the intermediate transfer belt 20. The secondary transfer roll 26 (an example of a secondary transfer unit) thus formed reaches a secondary transfer portion.
On the other hand, the recording paper P (an example of a recording medium) is fed at a predetermined timing into a gap where the secondary transfer roll 26 and the intermediate transfer belt 20 are pressed through the supply mechanism, and the secondary transfer bias is applied. Applied to the back roll 24. The transfer bias applied at this time is a (−) polarity that is the same polarity as the polarity (−) of the toner, and an electrostatic force from the intermediate transfer belt 20 toward the recording paper P is applied to the toner image, and the transfer bias is applied to the intermediate transfer belt 20. The toner image is transferred onto the recording paper P. The secondary transfer bias at this time is determined in accordance with the resistance detected by a resistance detecting means (not shown) for detecting the resistance of the secondary transfer portion, and is voltage-controlled.

  Thereafter, the recording paper P is fed to the pressure contact portions (nip portions) of the pair of fixing rolls in the fixing device 28 (an example of the fixing unit), the toner image is heated, and the color-superposed toner images are melted. Fixed onto P.

  The recording paper P on which the color image has been fixed is unloaded to the discharge unit, and a series of color image forming operations is completed.

  The image forming apparatus according to the third embodiment is not limited to the above configuration, and a known intermediate transfer type image forming apparatus is applied as long as the image forming apparatus includes the transfer unit according to the first embodiment.

[Fourth Embodiment]
FIG. 6 is a schematic configuration diagram illustrating an image forming apparatus according to the fourth embodiment.
The image forming apparatus according to the fourth embodiment is a direct transfer type apparatus including the transfer unit according to the second embodiment as a primary transfer unit.

Specifically, the image forming apparatus according to the fourth embodiment includes, for example, a photoreceptor 1 (an example of an image carrier) as illustrated in FIG. Around the photosensitive member 1, a charging device 2 (for example, a charging roll: an example of a developing unit) that charges the surface of the photosensitive member 1 to a predetermined potential, a laser based on an image signal obtained by color-separating the charged surface. An exposure device 3 (an example of an electrostatic image forming unit) that forms an electrostatic image by exposure with light 3L, and a developing device 4 (an example of a developing unit) that supplies toner charged to the electrostatic image and develops the electrostatic image ), A primary transfer roll 5 (an example of a primary transfer unit) that transfers the developed toner image onto a recording paper P (an example of a recording medium), and a photoconductor that removes toner remaining on the surface of the photoconductor 1 after the primary transfer. A cleaning device 6 (an example of a cleaning unit) is sequentially arranged.
The primary transfer roll 5 is provided at a position facing the photoconductor 1. Further, the primary transfer roll 5 and a bias power source (not shown) for applying a primary transfer bias are connected. Each bias power source varies the transfer bias applied to the primary transfer roll 5 under the control of a control unit (not shown).

The operation for forming an image will be described below.
First, the charging device 2 charges the surface of the photoreceptor 1 to a potential for charging. Next, a laser beam 3L is output to the surface of the charged photoreceptor 1 through the exposure device 3 in accordance with image data sent from a control unit (not shown). The laser beam 3L is applied to the photosensitive layer on the surface of the photoreceptor 1, whereby an electrostatic charge image of a toner print pattern is formed on the surface of the photoreceptor 1.

  Next, the photoreceptor 1 rotates, and the electrostatic image formed on the photoreceptor 1 is visualized (developed image) by the developing device 4. Specifically, the electrostatic charge image formed on the surface of the photoconductor 1 passes through the developing device 4 so that the toner is electrostatically attached to the latent image portion on the surface of the photoconductor 1 that has been neutralized. The electrostatic latent image is developed with toner.

Next, the photosensitive member 1 rotates and the formed toner image is conveyed to the primary transfer unit. When the toner image on the photoreceptor 1 is conveyed to the primary transfer, a primary transfer bias is applied to the primary transfer roll 5, and an electrostatic force from the photoreceptor 1 toward the primary transfer roll 5 is applied to the toner image. The upper toner image is transferred onto the recording paper P (an example of a recording medium).
The toner remaining on the photoreceptor 1 is removed by the cleaning device 6 and collected.

  Thereafter, the recording paper P is fed to the pressure contact portions (nip portions) of a pair of fixing rolls in the fixing device 28 (an example of the fixing unit), the toner image is heated, and the toner image is melted, onto the recording paper P. It is fixed.

  The recording paper P on which the fixing of the toner image is completed is carried out toward the discharge unit, and a series of image forming operations is completed.

  Note that the image forming apparatus according to the fourth embodiment is not limited to the above configuration, and a known direct transfer type image forming apparatus is applied as long as the image forming apparatus includes the transfer unit according to the second embodiment.

  Here, in all the embodiments, the recording paper P to which the toner image is transferred includes, for example, plain paper used for an electrophotographic copying machine, a printer, or the like. In addition to the recording paper P, an OHP sheet or the like may be applied as a recording medium.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.
In the following, “part” and “%” are based on mass unless otherwise specified.

[Example 1]
(Preparation of transfer roll (1))
By containing an ethylene oxide group, 60 parts of epichlorohydrin rubber (Epichromer CG-102 manufactured by Daiso Corporation) and 30 parts of acrylonitrile-butadiene rubber (Nipol DN-219 manufactured by Nippon Zeon Co., Ltd.), carbon black (MA100: 5 parts of Mitsubishi Chemical Corporation) and 55 parts of lead zirconate titanate particles (PZT: trade name “Z-711 (manufactured by Ceratech), average particle size = 500 μm, piezoelectric strain constant = 610 pC / N)” (However, the number of parts relative to 100 parts of the total elastic material) is mixed with 1 part of sulfur (200 mesh manufactured by Tsurumi Chemical Co., Ltd.) and 1.5 parts of vulcanization accelerator (Noxera-M manufactured by Ouchi Shinsei Chemical Co., Ltd.). Were mixed with an open roll to obtain a mixture, which was then applied to a SUS shaft (support) having a diameter of 14 mm. Subsequently, the SUS shaft was heated to 160 ° C. as a heat source, and the wound mixture was vulcanized and foamed for 2 hours to form an elastic layer on the SUS shaft. Then, it was processed into φ28 mm (elastic layer thickness 7 mm) to obtain a roll with an elastic layer.

  When the measuring needle of an Asker C type hardness meter (manufactured by Kobunshi Keiki Co., Ltd.) was pressed against the surface of the elastic layer of the roll with an elastic layer and measured under the condition of 1000 g load, the Asker C hardness was 75 °. This roll with an elastic layer was used as a transfer roll (1).

[Examples 2 to 6, Comparative Example (C3)]
Transfer rolls (2) to (6) and (C3) were prepared in the same manner as the transfer roll (1) except that the composition of the elastic layer (type and amount of each component) was changed according to Table 1. In Table 1, the amount of the piezoelectric material indicates the number of parts relative to 100 parts of the total elastic material (that is, the ratio of mass to the elastic material (mass%)).

[Comparative Example 1]
A transfer roll (C1) was produced in the same manner as in Example 1 (transfer roll (1)) except that the lead zirconate titanate particles were not blended.

[Comparative Example 2]
As shown below, a transfer roll (C2) containing an elastic layer containing silicone rubber and a piezoelectric material and having an Asker C hardness of less than 60 ° was produced.
PZT is mixed in uncured silicon rubber in a blending amount according to Table 1, 1 part of sulfur (200 mesh manufactured by Tsurumi Chemical Co., Ltd.), and a vulcanization accelerator (Noxera-M manufactured by Ouchi Shinsei Chemical Co., Ltd.). 1.5 parts was added and kneaded with an open roll to obtain a mixture. Next, this mixture was wound around a SUS shaft (support) having a diameter of 14 mm. Subsequently, the SUS shaft was heated to 160 ° C. as a heat source, and the wound mixture was vulcanized and foamed for 2 hours to form an elastic layer on the SUS shaft. The outer peripheral surface of this elastic layer was polished and processed into φ28 mm (elastic layer thickness 7 mm) to obtain a transfer roll (C2).

[Evaluation]
The following evaluation was performed about the secondary transfer unit which combined each produced transfer roll as a secondary transfer roll, and combined the roll A with the following elastic layer as a back roll. The evaluation results are shown in Table 1.

-Production of roll A with elastic layer-
By containing an ethylene oxide group, 60 parts of epichlorohydrin rubber (Epichromer CG-102 manufactured by Daiso Corporation) and 30 parts of acrylonitrile-butadiene rubber (Nipol DN-219 manufactured by Nippon Zeon Co., Ltd.), carbon black (MA100: 5 parts of Mitsubishi Chemical Corporation), 1 part of sulfur (200 mesh manufactured by Tsurumi Chemical Co., Ltd.), 1.5 part of vulcanization accelerator (Noxera-M manufactured by Ouchi Shinsei Chemical Co., Ltd.) And kneaded with an open roll to obtain a mixture. Next, this mixture was wound around a SUS shaft (support) having a diameter of 28 mm. Subsequently, the SUS shaft was heated to 160 ° C. as a heat source, and the wound mixture was vulcanized and foamed for 2 hours to form an elastic layer on the SUS shaft. The outer peripheral surface of this elastic layer was polished and processed into an outer diameter of 42 mm (elastic layer thickness 7 mm) to obtain a roll A with an elastic layer.
When measured under the condition of a load of 1000 g by pressing a measuring needle of an Asker C-type hardness meter (manufactured by Kobunshi Keiki Co., Ltd.) on the surface of the elastic layer of the roll A with an elastic layer, the Asker C hardness was 70 °.

-Image quality evaluation-
The secondary transfer unit was incorporated in a secondary transfer portion of an image forming apparatus “700 Digital Color Press (intermediate transfer system apparatus including an intermediate transfer belt)” manufactured by Fuji Xerox Co., Ltd. After outputting 100,000 halftone images (image density 30%) on A3 size J paper in an environment of 10 ° C./15% RH using this apparatus. A halftone image (image density 30%) was output on SRA3 size paper, and the image quality of the image was visually evaluated. The evaluation criteria are as follows.
G1: Generation of white spots in the image was not confirmed.
G2: Slight white spots in the image occurred in an area corresponding to a non-sheet passing portion of A3 size J paper.
G3: In the area corresponding to the non-sheet passing portion of A3 size J paper, white spots of the image occurred at a level that does not cause a problem in image quality.
NG: An image white spot has occurred in an area corresponding to a non-sheet passing portion of A3 size J paper.

-Resistance measurement-
After the image quality evaluation, the secondary transfer roll and the intermediate transfer belt were taken out from the apparatus.
Then, the taken out secondary transfer roll was placed on a metal flat plate, and a 1 cm wide metal electrode was brought into contact with a region corresponding to a non-sheet passing portion of A3 size J paper in the secondary transfer roll. Then, a voltage of 1000 V is applied between the metal shaft and the metal electrode of the secondary transfer roll with the metal flat plate as the ground, and the resistance value (LogΩ) of the non-sheet passing portion of the secondary transfer roll is calculated from the flowing current. did. Next, the resistance value (Log Ω) was calculated in the same manner in a state where a 1 cm wide metal electrode was in contact with a region corresponding to the sheet passing portion of A3 size J paper in the secondary transfer roll. Then, a resistance value difference between the sheet passing portion and the non-sheet passing portion of the secondary transfer roll (indicated as “2nd BTR: resistance difference between the paper portion and the non-sheet passing portion” in Table 1) was examined.

  On the other hand, the surface resistivity (LogΩ / □) of the area corresponding to the non-sheet passing portion of the A3 size J paper in the taken out intermediate transfer member was measured according to JIS-K-6911 (1995) using a circular electrode (Mitsubishi Oil Chemical Co., Ltd.). High Urester IP “UR probe”). However, the applied voltage of the circular electrode was 100V. Next, the surface resistivity (LogΩ / □) of the region corresponding to the sheet passing portion of A3 size J paper in the intermediate transfer member was also measured in the same manner. Then, the surface resistance difference between the sheet passing portion and the non-sheet passing portion of the intermediate transfer member (indicated as “ITB: resistance difference between the paper portion and the non-sheet passing portion” in Table 1) was examined.

From the above results, in this embodiment, better image quality evaluation was obtained than in Comparative Example 1. Thus, in this embodiment, it was shown that the occurrence of white spots in the image was suppressed even when the size of the recording medium was changed as compared with Comparative Example 1.
In Comparative Example 2, since silicone rubber is used as an elastic material, the elastic layer has a low Asker C hardness of 60 ° C. or less, a low paper peelability, and a thin paper intermediate transfer belt winding jam occurs. There has occurred. On the other hand, in Comparative Example 1 in which the elastic layer having a hardness exceeding 60 ° C. was provided, no jamming occurred on the thin paper intermediate transfer belt, but gap discharge occurred, and white spots of the image occurred. Recognize.

Hereinafter, details such as abbreviations in the table will be described.
-Elastic material-
EPO: Epichlorohydrin rubber containing ethylene oxide group (Epichromer CG-102 manufactured by Daiso Corporation)
・ NBR: Acrylonitrile-butadiene rubber (Nipol DN-219 manufactured by Nippon Zeon Co., Ltd.)
・ Si: Silicone rubber (“Thermosetting silicone rubber KE-106” manufactured by Shin-Etsu Chemical Co., Ltd.)

-Conductive agent-
-CB; carbon black (MA100: manufactured by Mitsubishi Chemical Corporation)

-Piezoelectric materials-
PZT: lead zirconate titanate particles (trade name “Z-711 (manufactured by Ceratech), average particle size = 500 μm, piezoelectric strain constant = 610 pC / N)
BaTiO ₃ : Barium titanate particles (manufactured by TPL, average particle size = 400 μm, piezoelectric strain constant = 300 pC / N)
SrTiO ₃ : Strontium titanate particles (manufactured by TPL), average particle size = 400 μm, piezoelectric strain constant = 300 pC / N)

-Additives-
・ Sulfur: 200 mesh manufactured by Tsurumi Chemical Co., Ltd. ・ Vulcanization accelerator: Noxera-M manufactured by Ouchi Shinsei Chemical Co., Ltd.

1, 1Y, 1M, 1C, 1K photoreceptor 2, 2Y, 2M, 2C, 2K charging roll 3L, 3Y, 3M, 3C, 3K laser beam 3 exposure device 4, 4Y, 4M, 4C, 4K developing device 5, 5Y 5M, 5C, 5K Primary transfer rolls 6, 6Y, 6M, 6C, 6K Cleaning devices 8Y, 8M, 8C, 8K Toner cartridges 10Y, 10M, 10C, 10K Image forming unit 20 Intermediate transfer belt 22 Drive roll 24 Back roll 26 Secondary transfer roll 26A Support 25B Elastic layer 28 Fixing device 30 Intermediate transfer member cleaning device

Claims (7)

A transfer member comprising an elastic material and an elastic layer having an Asker C hardness of more than 60 ° as measured from the surface of the elastic layer, including a piezoelectric material having an average particle diameter of 60 μm or more whose volume increases by application of voltage.   The transfer member according to claim 1, wherein the elastic material is an elastic material excluding silicone rubber. The transfer member according to claim 1 or 2,
A facing member disposed to face the transfer member;
With
A transfer unit that transfers a toner image to a recording medium by applying an electric field between the transfer member and the opposing member when passing between the transfer member and the opposing member.   The transfer unit according to claim 3, wherein the Asker C hardness measured from the surface of the facing member is 50 ° or more.   An image forming apparatus comprising the transfer unit according to claim 3. An image carrier,
Charging means for charging the image carrier;
An electrostatic charge image forming means for forming an electrostatic charge image on the surface of the charged image carrier;
Developing means for developing, as a toner image, an electrostatic charge image formed on the image carrier with an electrostatic charge image developer containing toner;
An intermediate transfer member to which the toner image formed on the surface of the image carrier is transferred;
Primary transfer means for primarily transferring the toner image formed on the surface of the image carrier to the surface of the intermediate transfer member;
3. A secondary transfer unit that secondary-transfers the toner image transferred to the surface of the intermediate transfer member to a recording medium, and is disposed outside the intermediate transfer member, and the transfer member according to claim 1. And an opposing member disposed opposite to the transfer member inside the intermediate transfer member, and the recording medium passes between the transfer member and the opposing member via the intermediate transfer member. A secondary transfer unit that applies an electric field between the transfer member and the opposing member to secondarily transfer the toner image to the recording medium;
Fixing means for fixing the toner image transferred to the recording medium;
An image forming apparatus. An image carrier,
Charging means for charging the image carrier;
An electrostatic charge image forming means for forming an electrostatic charge image on the surface of the charged image carrier;
Developing means for developing, as a toner image, an electrostatic charge image formed on the image carrier with an electrostatic charge image developer containing toner;
Transfer means for transferring a toner image formed on the image holding body onto a recording medium, the transfer means being provided facing the image holding body, comprising the transfer member according to claim 1, A transfer unit that applies an electric field between the transfer member and the image carrier when the recording medium passes between the transfer member and the image carrier, and transfers the toner image to the recording medium; ,
Fixing means for fixing the toner image transferred onto the recording medium;
An image forming apparatus comprising:

Images