JP2013171218A - Image formation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image formation apparatus capable of optimally applying bias without leakage of bias voltage applied to a first conductive layer of a transfer cylinder bias sheet to an impression cylinder side.SOLUTION: An image formation apparatus comprises: an image carrier 10 rotatably supported at a housing 1 and configured to form an electrostatic latent image thereon and to develop a toner image according to the electrostatic latent image thereon; a transfer cylinder 200 rotatably supported at the housing 1 and configured to receive a toner image developed on the image carrier 10 transferred thereon; an impression cylinder 300 rotatably supported at the housing 1 and configured to insert a recording medium between the transfer cylinder 200 and to transfer the toner image on the transfer cylinder 200 to the recording medium; a ring-shaped electrode 210 fixed at a side end face of the transfer cylinder 200 coaxially with an axis of the transfer cylinder 200; and a power supply electrode 220 configured to make contact with the ring-shaped electrode 210 from a side opposite to a side end face 204 of the transfer cylinder 200 in an axial direction of the transfer cylinder 200 and to supply power.

Description

  The present invention relates to an image forming apparatus that develops a latent image formed on a photoreceptor with a developer composed of toner and carrier, and transfers the developed image to a recording medium to form an image.

  Various wet image forming apparatuses that develop a latent image using a high-viscosity liquid developer in which a toner composed of a solid component is dispersed in a liquid solvent and visualize the electrostatic latent image have been proposed. The developer used in this wet image forming apparatus suspends solids (toner particles) in a highly viscous organic solvent (carrier liquid) having electrical insulation properties such as silicone oil, mineral oil, and edible oil. The toner particles are extremely fine with a particle diameter of around 1 μm. By using such fine toner particles, the wet image forming apparatus can achieve higher image quality than a dry image forming apparatus using powder toner particles having a particle diameter of about 7 μm.

  As an image forming apparatus using the liquid developer as described above, Patent Document 1 (Japanese Patent Laid-Open No. 2004-317980) discloses that an electrostatic latent image formed on the surface of the photoreceptor 1 can be transferred by the developing device 4. By visualizing (developing), a toner image is formed on the surface of the photoreceptor 1, and this toner image is primarily transferred onto the intermediate transfer drum 5, and then primary transferred onto the intermediate transfer drum 5. The toner image is secondarily transferred onto a paper 9 conveyed to a nip between the intermediate transfer drum 5 and the secondary transfer drum 8.

JP 2004-317980 A Japanese Patent Laid-Open No. 5-278195

  In the conventional image forming apparatus, in the technique described in Patent Document 1, it is necessary to apply an appropriate bias voltage to the intermediate transfer drum and the secondary transfer drum in order to transfer the toner image. On the other hand, as a base material for the intermediate transfer drum or the secondary transfer drum, a conductive metal material is used in order to obtain accuracy. Therefore, in order to appropriately apply a bias voltage to the peripheral surfaces of the intermediate transfer drum and the secondary transfer drum without causing a leakage current, a metal substrate such as the intermediate transfer drum or the secondary transfer drum is used. This must be done with material and insulation secured.

  However, Patent Document 1 does not disclose a specific structure for appropriately applying a bias voltage to the peripheral surface of an intermediate transfer drum, a secondary transfer drum, or the like, which is a problem.

  Patent Document 2 describes a technique for applying a voltage to an impression cylinder by insulating a bearing of the impression cylinder and supplying power to a shaft.

  However, in the case of an image forming apparatus in which the cylinder member is separated from other cylinders for maintenance, cleaning, etc., leakage current may be required unless the contact point for supplying power is properly disposed even during movement. May occur.

  SUMMARY An advantage of some aspects of the invention is that an image forming apparatus according to the present invention is rotatably supported by a housing to form an electrostatic latent image, and a toner image based on the electrostatic latent image is developed. An image carrier to which the toner image developed on the image carrier is transferred, and a transfer cylinder rotatably supported by the housing. A pressure cylinder for transferring the toner image on the transfer cylinder onto the recording medium, and a ring electrode fixed to a side end surface of the transfer cylinder concentrically with the axis of the transfer cylinder And a power supply electrode that contacts the ring-shaped electrode in the axial direction of the transfer cylinder from the side opposite to the side end face of the transfer cylinder and supplies power.

  In the image forming apparatus according to the present invention, the transfer cylinder can contact and be separated from the image carrier and the impression cylinder.

  The image forming apparatus according to the present invention further includes a power supply electrode support member that supports the power supply electrode.

  In the image forming apparatus according to the present invention, the power supply electrode support member is supported by the housing, the transfer cylinder is in contact with the image carrier and the impression cylinder, and the transfer cylinder. Is separated from the image carrier and the impression cylinder, the power feeding electrode contacts the ring electrode.

  In the image forming apparatus according to the present invention, the feeding electrode includes a position of the ring-shaped electrode in a state where the transfer cylinder is in contact with the image carrier and the impression cylinder, and the transfer cylinder is the The ring-shaped electrode is in contact with the ring-shaped electrode at a position where the position of the ring-shaped electrode that is separated from the image carrier and the impression cylinder intersects.

  As described above, in the image forming apparatus of the present invention, the electrostatic latent image is formed by being rotatably supported by the housing, and the toner image based on the electrostatic latent image is developed, and the image carrier is rotated by the housing. A transfer cylinder to which the toner image developed on the image carrier is transferred in a supported manner, and a support that is rotatably supported by the housing, and a recording medium is inserted between the transfer cylinder and the transfer cylinder. A pressure drum for transferring the toner image on the transfer cylinder to a recording medium; a ring-shaped electrode fixed concentrically with a shaft of the transfer cylinder on a side end surface of the transfer cylinder; and the ring in the axial direction of the transfer cylinder. A feeding electrode that contacts and feeds power from the side opposite to the side end surface of the transfer cylinder, so that the influence of vibration due to rotation can be reduced, and the transfer electrode can be stably brought into contact with the transfer cylinder. Therefore, it is possible to supply power appropriately.

  In the image forming apparatus according to the present invention, the transfer cylinder can be brought into contact with and separated from the image carrier and the impression cylinder. Therefore, the image carrier and the impression cylinder are separated from each other in the unrolled state. Therefore, it is possible to prevent toner, carrier oil, and the like from moving between the members.

  In addition, since the image forming apparatus according to the present invention includes the power supply electrode support member that supports the power supply electrode, the image forming apparatus includes the power supply electrode support member that supports the power supply electrode. It is possible to abut.

  In the image forming apparatus according to the present invention, the power supply electrode support member is supported by the housing, the transfer cylinder is in contact with the image carrier and the impression cylinder, and the transfer cylinder. Is separated from the image carrier and the impression cylinder, and the feeding electrode contacts the ring-shaped electrode. Therefore, when the transfer cylinder is unrolled and moved, the feeding electrode becomes the ring-shaped electrode portion. It is possible to reduce the risk of bumping and deforming with a strong impact. In addition, it is not necessary to reset the position at the time of cylinder insertion, and printing can be easily resumed.

  In the image forming apparatus according to the present invention, the feeding electrode includes a position of the ring-shaped electrode in a state where the transfer cylinder is in contact with the image carrier and the impression cylinder, and the transfer cylinder is the Since the ring-shaped electrode contacts the ring-shaped electrode at a position where the position of the ring-shaped electrode that is separated from the image carrier and the impression cylinder intersects, when the transfer cylinder is unrolled and moved, It is possible to further reduce the possibility that the power supply electrode collides with the ring-shaped electrode portion with a strong impact and is deformed. In addition, it is not necessary to reset the position at the time of cylinder insertion, and printing can be easily resumed. Furthermore, the contact pressure between the power supply electrode and the ring-shaped electrode portion can be made substantially constant.

1 is a diagram illustrating main components constituting an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a cross-sectional view illustrating main components of an image forming unit and a developing device. It is a figure which shows the outline | summary of the nip which a transfer cylinder and an impression cylinder form. FIG. 4 is a perspective view showing a side end portion of a transfer cylinder in the image forming apparatus according to the embodiment of the present invention. FIG. 3 is a cross-sectional view in the axial direction of a side end portion of a transfer cylinder in the image forming apparatus according to the embodiment of the present invention. It is a figure which shows the ring-shaped electrode in the image forming apparatus which concerns on embodiment of this invention. FIG. 3 is a diagram illustrating a state when the transfer cylinder is inserted into the image forming apparatus according to the embodiment of the present invention. FIG. 3 is a diagram illustrating a state when the transfer cylinder is unrolled in the image forming apparatus according to the embodiment of the present invention. It is a figure which shows the state before and behind the movement of the ring-shaped electrode in the image forming apparatus which concerns on embodiment of this invention. It is a figure which shows the electric power feeding electrode in the image forming apparatus which concerns on other embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing main components constituting the image forming apparatus according to the embodiment of the present invention. In FIG. 1, the arrows attached to the rollers and the body portions indicate the rotation directions of the respective configurations.

  The image forming unit in the image forming apparatus includes photoreceptors 10Y, 10M, 10C, and 10K, corona chargers 11Y, 11M, 11C, and 11K, exposure units 12Y, 12M, 12C, and 12K. The photoconductors 10Y, 10M, 10C, and 10K are uniformly charged by the corona chargers 11Y, 11M, 11C, and 11K, and are mounted on the exposure units 12Y, 12M, 12C, and 12K based on the input image signals. By driving the exposure head, an electrostatic latent image is formed on the charged photoreceptors 10Y, 10M, 10C, and 10K.

  The developing devices 30Y, 30M, 30C, and 30K generally include liquid developers of respective colors including the developing rollers 20Y, 20M, 20C, and 20K, yellow (Y), magenta (M), cyan (C), and black (K). Developer containers (reservoirs) 31Y, 31M, 31C, 31K to be stored, and application rollers for applying liquid developers of these colors from the developer containers 31Y, 31M, 31C, 31K to the developing rollers 20Y, 20M, 20C, 20K. Anilox rollers 32Y, 32M, 32C, and 32K are provided, and the electrostatic latent images formed on the photoreceptors 10Y, 10M, 10C, and 10K are developed as toner images with liquid developers of the respective colors.

  The toner images formed on the photoreceptors 10Y, 10M, 10C, and 10K are transferred to the transfer cylinders 200Y, 200M, 200C, and 200K to which a predetermined bias voltage is applied by the primary transfer units 50Y, 50M, 50C, and 50K, respectively. Is done.

  The paper feed unit 100 supplies the recording medium to the first impression cylinder 300 by a clamp mechanism (not shown) provided in the recess 102.

  The first impression cylinder 300 is provided with two concave portions 302 so as to be opposed to each other, and each concave portion 302 is provided with a clamp mechanism (not shown). The recording medium can be conveyed by being wound around the body, wound around the body, and rotated about the shaft 301.

  Similarly, the first transfer drum 400 is provided with two concave portions 402 so as to be opposed to each other, and each concave portion 402 is provided with a clamp mechanism (not shown), and can store up to two recording media. The recording medium can be conveyed by being clamped by the clamp mechanism, wound around the body, and rotated around the shaft 401.

  The second transfer drum 500 is provided with three concave portions 502 at equal intervals, and each concave portion 502 is provided with a clamp mechanism (not shown), and holds up to three recording media by the clamp mechanism. Then, the recording medium can be conveyed by winding it around the body and rotating it around the shaft 501.

  Further, the third transfer drum 600 is provided with two concave portions 602 so as to face each other, and each concave portion 602 is provided with a clamp mechanism (not shown) so that a maximum of two recording media can be stored. The recording medium can be conveyed by being clamped by a clamp mechanism, wound around a body portion, and rotated around a shaft portion 601.

  The second impression cylinder 700 is provided with two recesses 702 so as to be opposed to each other, and each of the recesses 702 is provided with a clamp mechanism (not shown). The recording medium can be conveyed by being wound around the body portion, wound around the body portion, and rotated around the shaft portion 701. The configuration of the second impression cylinder 700 is the same as that of the first impression cylinder 300.

  The paper discharge unit 800 conveys the recording medium to the fixing unit 90 by a clamp mechanism (not shown) provided in the concave portion 802.

  In the configuration described above, the recording medium picked up by the paper feed unit 100 in (a) is then transferred from the paper feed unit 100 to the first impression cylinder 300 that rotates counterclockwise in (b). Then, in (c), it is transferred from the first impression cylinder 300 to the first transfer cylinder 400 that rotates clockwise, and in (d), the second that rotates counterclockwise from the first transfer cylinder 400. Then, it is transferred to the transfer cylinder 500, then transferred from the second transfer cylinder 500 in (e) to the third transfer cylinder 600 that rotates clockwise, and then transferred from the third transfer cylinder 600 in (f). The sheet is transferred to the second impression cylinder 700 that rotates clockwise, and then transferred to the paper discharge unit 800 from the second impression cylinder 700 and guided to the fixing unit 90 in (g). That is, the conveyance path of the recording medium is indicated by a dotted line in the drawing.

  When the recording medium passes through the conveyance path as described above, the toner images primarily transferred to the transfer cylinders 200Y, 200M, 200C, and 200K are sequentially transferred to the recording medium, and a full-color toner image is formed on the recording medium. Is formed.

  More specifically, the recording medium is yellow (Y) at the secondary transfer portions 60Y and 60M formed at the nip between the transfer cylinders 200Y and 200M and the first impression cylinder 300 to which a predetermined bias is applied. The toner image of magenta and the toner image of magenta (M) are transferred, and further, a secondary transfer portion 60C formed at the nip between the transfer cylinders 200C and 200K and the second impression cylinder 700 to which a predetermined bias is applied. , 60K, respectively, a cyan (C) toner image and a black (K) toner image are transferred.

  Further, the recording medium conveyed from the paper discharge unit 800 to the fixing unit 90 is fused with a full-color toner image by the fixing unit 90 to become a permanent visible image.

Next, the image forming unit and the developing device of the image forming apparatus according to the embodiment of the present invention will be described. FIG. 2 is a sectional view showing main components of the image forming unit and the developing device. Since the configurations of the image forming unit and the developing device for each color are the same, the following description is based on the yellow (Y) image forming unit and the developing device.
The image forming unit includes a photoconductor cleaning blade 18Y, a corona charger 11Y, an exposure unit 12Y, a developing roller 20Y of the developing device 30Y, a photoconductor squeeze roller 13Y, and a photoconductor squeeze roller along the rotation direction of the outer periphery of the photoconductor 10Y. 13Y ′ is arranged.

  An elastic roller 16Y is disposed on the outer periphery of the developing roller 20Y in the developing device 30Y. The anilox roller 32Y contacts the elastic roller 16Y, and the anilox roller 32Y is immersed in the liquid developer stored in the liquid developer container 31Y.

  In the liquid developer container 31Y of the developing device 30Y, the liquid developer in a state where the toner is dispersed in a weight ratio of about 25% is stored in the carrier. The liquid developer contained in the developer container 31Y is a low-concentration (about 1 to 3 wt%) and low-viscosity volatile at room temperature using a conventionally used Isopar (trademark: exon) as a carrier. Is a non-volatile liquid developer having a high concentration and high viscosity and having non-volatility at room temperature.

That is, the liquid developer in the present invention is a liquid such as an organic solvent, silicone oil, mineral oil or edible oil obtained by dispersing solid toner particles having an average particle diameter of 1 μm in which a colorant such as a pigment is dispersed in a thermoplastic resin. A high-viscosity liquid developer that is added to a solvent together with a dispersant and has a toner solid content concentration of about 25%.
The anilox roller 32Y functions as an application roller that supplies and applies a liquid developer to the elastic roller 16Y. The anilox roller 32Y is a cylindrical member, and is a roller having a concave and convex surface formed by grooves engraved finely and uniformly on the surface so as to easily carry the liquid developer on the surface. The anilox roller 32Y supplies the liquid developer from the developer container 31Y to the developing roller 20Y.

The anilox roller 32Y rotates counterclockwise to apply the liquid developer to the elastic roller 16Y that rotates clockwise. The liquid developer applied to the elastic roller 16Y by the anilox roller 32Y is supplied to the developing roller 20Y that rotates clockwise.
The developing roller 20Y is a cylindrical member, and rotates clockwise around the rotation axis as shown in FIG. The developing roller 20Y is provided with an elastic layer made of polyurethane rubber, silicon rubber, NBR or the like on the outer peripheral portion of an inner core made of metal such as iron, and further provided with a coating of PFA or urethane coat on the elastic layer.

  As for the elastic roller 16Y, an elastic layer such as polyurethane rubber, silicon rubber, NBR or the like is provided on the outer peripheral portion of an inner core made of metal such as iron, and further, this elastic layer is provided with a coating of PFA or urethane coat.

  The liquid developer carried on the developing roller 20Y moves corresponding to the latent image on the photoconductor 10Y and develops it by applying a desired electric field at the developing nip where the developing roller 20Y contacts the photoconductor 10Y.

  The photoconductor squeeze rollers 13Y and 13Y ′ arranged on the upstream side of the primary transfer unit are arranged on the downstream side of the developing roller 20Y so as to face the photoconductor 10Y, and an excessive toner image developed on the photoconductor 10Y. It has a function of collecting the carrier and the originally unnecessary fog toner and increasing the toner particle ratio in the visible image.

  The primary transfer unit 50Y transfers the toner image developed on the photoreceptor 10Y to the transfer cylinder 200Y to which a predetermined bias is applied. Here, the photoconductor 10Y and the transfer cylinder 200Y are configured to rotate at a constant speed, thereby reducing the rotation and driving load and suppressing the disturbance effect on the visible toner image of the photoconductor 10Y. On the downstream side of the primary transfer, the photoconductor cleaning blade 18Y that is in contact with the photoconductor 10Y cleans the liquid developer remaining on the photoconductor 10Y without being transferred.

  A carrier liquid application roller 280Y and a transfer cylinder cleaning roller 290Y are disposed on the downstream side of the primary transfer portion 50Y of the transfer cylinder 200Y. The carrier liquid application roller 280Y rotates with the transfer cylinder 200Y, supplies the carrier liquid to the transfer cylinder 200Y, and wets the transfer cylinder 200Y. The transfer cylinder cleaning roller 290Y cleans toner particles remaining on the transfer cylinder 200Y by counter-rotating with respect to the transfer cylinder 200Y to which the carrier liquid is supplied.

  The toner image primarily transferred to the transfer cylinder 200Y is clamped by the first impression cylinder 300 at the secondary transfer portion 60Y formed at the nip with the first impression cylinder 300 to which a predetermined bias is applied. The image is gripped by a mechanism (not shown), and is secondarily transferred to a recording medium wound around and conveyed.

  Here, as the base material of the transfer cylinder 200Y and the first impression cylinder 300, a conductive metal material is used for accuracy, and the base material of the transfer cylinder 200Y and the first impression cylinder 300 is grounded. However, it is necessary to apply an appropriate bias voltage to the peripheral surface of these structures for transferring the toner image.

  Hereinafter, the structure of the transfer cylinder 200Y and the first impression cylinder 300 using the conductive base material will be described in detail.

  Since the transfer cylinder 200Y has the same configuration as the other transfer cylinders 200M, 200C, and 200K, the suffix Y indicating yellow is omitted below. In addition, the first impression cylinder 300 is configured in common with the second impression cylinder 700, but in order to indicate that these are separate bodies, “first” and “second” are added and distinguished. It was. Hereinafter, the “first” of the first impression cylinder 300 may be omitted and referred to as the impression cylinder 300.

  A transfer cylinder bias sheet 250 and a blanket sheet 260 are wound around the peripheral surface 203 of the transfer cylinder 200, and a bias voltage is applied to the peripheral surface of the transfer cylinder 200 by supplying power to the transfer cylinder bias sheet 250. The Rukoto.

  Further, a concave portion 202 extending in the axial direction is provided in a part of the peripheral surface 203 of the transfer cylinder 200. The recess 202 faces the recess 302 of the first impression cylinder 300 in synchronization with the transfer cylinder 200 rotating. The recess 202 accommodates a winding rotary body (not shown) having a substantially cylindrical shape for winding the transfer cylinder bias sheet 250 and the blanket sheet 260 around the peripheral surface 203 in a tensioned state.

  As shown in FIG. 3, the transfer cylinder bias sheet 250 includes a base layer 251 having an insulating property and a conductive layer 252 having a conductivity formed on the base layer 251.

  Examples of the resin material used for the base material layer 251 of the transfer cylinder bias sheet 250 include polyimide resin, polyamideimide resin, fluorine resin, vinyl chloride vinyl acetate copolymer, polycarbonate (PC), polyethylene terephthalate (PET), Examples thereof include vinyl chloride resins, ABS resins, polymethyl methacrylate (PMMA), polyester resins such as polybutylene terephthalate (PBT), and polyamide (PA). These may be used alone or in combination of two or more. Among these, the polyimide resin is preferable in that it is not affected by the drying temperature when the above-described charge transport layer, charge generation layer, and undercoat layer are coated and dried, and is excellent in both structural strength and bending fatigue. Used for.

  In addition, the Young's modulus of the base material layer 251 of the transfer cylinder bias sheet 250 is 3000 MPa or more, but it is 6500 MPa or less due to restrictions on the manufacture of the base material, and the others are not particularly limited. The Young's modulus is more preferably in the range of 3500 MPa to 6000 MPa. In order to obtain the base material which has the Young's modulus of the said range, it can achieve by using a polyimide resin etc.

  In addition, the tensile elasticity modulus (Young's modulus) of the base material layer 251 in the present invention conforms to JIS K 6251: 93, and AIKOH ENGINEERING CO. , LTD. It can measure using FA1015A made. In addition, the measurement is performed under the condition of a test speed of 20 mm / min using a sample obtained by cutting a base material in a strip shape (5 mm × 40 mm) as a sample.

  The conductive layer 252 of the transfer cylinder bias sheet 250 may be a coating containing carbon particles, ITO (Indium Tin Oxide) used for a transparent electrode, or the like. When ITO is used, an alloy in which about 1 to 5% by weight of tin oxide is added to indium oxide is preferable.

  Further, in manufacturing the transfer cylinder bias sheet 250, the base layer 251 may be partially coated with the conductive layer 252 where necessary, or a sheet coated with the conductive layer 252 on the entire surface may be etched. A conductive layer 252 may be obtained.

  Furthermore, elastic polyurethane or the like is used for the blanket sheet 260.

  When the transfer cylinder bias sheet 250 and the blanket sheet 260 are attached to the transfer cylinder 200, an appropriate sheet may be provided between the peripheral surface 203 of the transfer cylinder 200 and the transfer cylinder bias sheet 250. According to such a configuration, it is possible to suppress the leakage current from the transfer cylinder bias sheet 250 and the blanket sheet 260 to the main body of the transfer cylinder 200, and it is possible to cope with recording media having different thicknesses.

  Further, the blanket sheet 260 is configured so as to include the conductive layer 252 of the transfer cylinder bias sheet 250 in the planar direction, so that the bias voltage applied to the conductive layer 252 of the transfer cylinder bias sheet 250 is reduced. It is possible to enjoy the merit that it is difficult to leak to the side of the section.

  Next, the transfer cylinder 200 will be described in detail.

  FIG. 4 is a perspective view showing a side end portion of the transfer cylinder 200 in the image forming apparatus according to the embodiment of the present invention. FIG. 5 is a cross-sectional view in the axial direction of the side end portion of the transfer cylinder 200 in the image forming apparatus according to the embodiment of the present invention. FIG. 6 is a view showing a ring-shaped electrode and a power feeding electrode in the image forming apparatus according to the embodiment of the present invention.

  The shaft member 201 of the transfer cylinder 200 includes a first shaft part 201 a that allows the transfer cylinder 200 to rotate, and a second shaft part 201 b that is attached to the apparatus housing 1. As shown in FIG. 5, the first shaft portion 201 a supports the end surface 204 of the transfer cylinder 200 via the bearing 2. The bearing 2 is fixed to the first shaft portion 201a by a lock nut 3. Further, the second shaft portion 201 b is attached to the apparatus housing 1 via the bearing 4. The first shaft portion 201a and the second shaft portion 201b are eccentric, and the shaft center Oa of the first shaft portion 201a and the shaft center Ob of the second shaft portion 201b are arranged in parallel.

  A ring-shaped electrode 210 is arranged on the side end surface 204 of the transfer cylinder 200 concentrically with the first shaft portion 201 a of the transfer cylinder 200. In the present embodiment, the ring-shaped electrode 210 includes a ring-shaped electrode portion 211 disposed on the end surface 204 of the transfer cylinder 200, a connection electrode portion 212 that covers the ring-shaped electrode portion 211, and a connection electrode portion 212 that is a ring-shaped electrode portion. And a fixing member 213 such as a screw attached to 211.

  As shown in FIG. 6, an electric wire portion 205 is connected from the ring-shaped electrode portion 211. The electric wire part 205 is disposed on the insulating part 206 disposed on the side end surface 204 of the transfer cylinder 200 and is connected to the transfer cylinder bias sheet 250.

  In addition, as shown in FIG. 5, a power supply electrode support member 221 that supports a power supply electrode 220 that is connected to a power source (not shown) and that supplies power to the ring electrode 210 is attached to the device housing 1.

  As shown in FIGS. 4 to 6, the power supply electrode 220 is disposed so as to contact the ring-shaped electrode 210 from the outside in the axial direction opposite to the end surface 204 of the transfer cylinder 200. The power supply electrode 220 is supported so that the angle and position of the power supply electrode support member 221 can be adjusted.

  The power supply electrode 223 is preferably made of a material having a hardness higher than that of the ring-shaped electrode portion 211. For example, the feeding electrode 223 is preferably composed of phosphor bronze, a carbon brush, or the like, and the ring-shaped electrode portion 211 is preferably composed of a chromium cylinder, an alumina dispersion cylinder, or the like.

  Next, the movement at the time of cylinder removal for maintenance of the transfer cylinder 200 will be described.

  FIG. 7 is a view showing a state when the transfer cylinder 200 is inserted into the image forming apparatus according to the embodiment of the present invention. FIG. 8 is a view showing a state when the transfer cylinder 200 is removed from the image forming apparatus according to the embodiment of the present invention. FIG. 9 is a diagram illustrating a state before and after the movement of the ring-shaped electrode 210 in the image forming apparatus according to the embodiment of the present invention.

  As shown in FIG. 7, the transfer cylinder 200 in the image forming apparatus according to the present embodiment is in a cylinder-inserted state in which a nip portion is formed in contact with the photoreceptor 10 and the impression cylinder 300 as shown in FIG. The transfer cylinder 200 can be moved from the cylinder-inserted state to the cylinder-extracted state by moving the transfer cylinder 200 as shown in FIG. 8 when the printing operation is completed or when cleaning or maintenance is performed.

  The cylinder removal state is performed by rotating the transfer cylinder 200 with respect to the apparatus housing 1 about the axis center Ob of the second shaft portion 201b. The rotation may be performed manually by a lever (not shown) or may be performed by a motor or the like.

  Since the power supply electrode support member 221 is supported by the device housing 1, it does not move. In this case, as shown in FIG. 9, the feeding electrode support member 221 is preferably set at a position where it can contact both the ring-shaped electrode 210 before moving and the ring-shaped electrode 210 ′ after moving. .

  Accordingly, during the movement, the power feeding electrode 220 rotates while being in contact with the ring electrode 210. By arranging in this way, when the transfer cylinder 200 is unrolled and moved, the possibility that the feeding electrode 220 collides with the ring electrode 210 with a strong impact and is deformed can be reduced. In addition, it is not necessary to reset the position at the time of cylinder insertion, and printing can be easily resumed. Further, for example, in the case of the structure having the carrier liquid application roller 280, the transfer cylinder cleaning roller 290, etc. shown in FIG. 2 in contact with the transfer cylinder 200, the transfer cylinder 200, the carrier liquid application roller 280, the cleaning roller 290, etc. Thus, it is possible to clean the transfer cylinder 200 while feeding power from the feeding electrode 220 to the ring electrode 210 even when the cylinder is removed.

  In the cylinder-extracted state, the photoconductor 10 and the impression cylinder 300 are separated from each other so that toner, carrier oil, and the like cannot move between the members. Further, it is possible to reduce the possibility that the transfer cylinder bias sheet 250, the blanket sheet 260, the impression cylinder bias sheet 330, and the like are deformed by the contact.

  In the present embodiment, the transfer cylinder 200 is unrolled and moved when the cylinder is inserted by using the eccentricity of the shaft. However, the shaft of the transfer cylinder 200 is slid and moved with respect to the apparatus housing 1. Also good. In this case, there is no need for a structure in which the two shaft portions are decentered, and the structure may be configured with one shaft center.

  FIG. 10 is a diagram showing power supply electrodes in an image forming apparatus according to another embodiment of the present invention.

  FIG. 10A shows a structure in which the feeding electrode 223 is provided via a compression spring 224. By using the compression spring 224, it is possible to absorb the stress by the compression spring 224 contracting when contacting the ring electrode 210. Therefore, it is possible to extend the life of the feeding electrode 223 and the ring-shaped electrode 210.

  FIG. 10B shows a structure in which a carbon brush 225 is attached to the end of the feeding electrode 223. By attaching the carbon brush 225, the carbon brush 225 is worn when contacting the ring-shaped electrode 210, and the stress on the ring-shaped electrode 210 can be reduced. Therefore, it is possible to extend the life of the feeding electrode 223 and the ring-shaped electrode 210.

  FIG. 10C shows a structure in which the feeding electrode 223 is formed in a linear shape. By forming the power supply electrode 223 in a linear shape, the power supply electrode 223 is easily bent when coming into contact with the ring-shaped electrode 210, and the stress can be weakened. Therefore, it is possible to extend the life of the feeding electrode 223 and the ring-shaped electrode 210.

  FIG. 10D shows a structure in which the feeding electrode 223 is formed in a brush shape. By forming the power supply electrode 223 in a brush shape, the power supply electrode 223 is easily bent when coming into contact with the ring-shaped electrode 210, and the stress can be weakened. Therefore, it is possible to extend the life of the feeding electrode 223 and the ring-shaped electrode 210.

  In addition, this invention is not limited by this embodiment. That is, in the description of the embodiments, many specific details are included for illustration, but those skilled in the art can add various variations and modifications to these details without departing from the scope of the present invention. It will be understood that this is not exceeded. Accordingly, the exemplary embodiments of the present invention have been described without loss of generality or limitation to the claimed invention.

  For example, although the present embodiment has been described with respect to a four-color image forming apparatus, it may be applied to a one-color image forming apparatus having one developing device, or two developing devices having two or more. You may apply to the image forming apparatus of a color or more.

10Y, 10M, 10C, 10K, photoconductor, 11Y, 11M, 11C, 11K, corona charger, 12Y, 12M, 12C, 12K, exposure unit, 13Y, 13Y ′, 13M, 13M ′. ..Photosensitive squeeze rollers, 16Y, 16M ... elastic rollers, 17Y, 17M ... elastic roller cleaning blades, 18Y, 18M ... photoconductor cleaning blades, 20Y, 20M, 20C, 20K ... developing rollers , 30Y, 30M, 30C, 30K ... developing device, 31Y, 31M, 31C, 31K ... developer container, 32Y, 32M, 32C, 32K ... anilox roller, 50Y, 50M, 50C, 50K ... Primary transfer part, 60Y, 60M, 60C, 60K ... Secondary transfer part, 90 ... Fixing unit, 00: paper feeding unit, 102: recess, 200Y, 200M, 200C, 200K ... transfer cylinder, 201 ... shaft, 202Y, 202M, 202C, 202K ... recess, 203 ... Peripheral surface, 204 ... side end face, 205 ... electric wire part, 210 ... ring electrode, 211 ... ring electrode part, 212 ... connection electrode part, 220 ... feeding electrode, 221 ... Feeding electrode support member, 250 ... Transfer cylinder bias sheet, 251 ... Base material layer, 252 ... Conductive layer, 260 ... Blanket sheet, 280Y ... Carrier liquid application roller, 290Y ..Transfer cylinder cleaning roller, 300... First pressure cylinder, 301... Shaft portion, 302... Concave portion, 330... Impression cylinder bias sheet, 331. Conductive layer, 40 ... first transfer drum, 401 ... shaft, 402 ... concave, 500 ... second transfer drum, 501 ... shaft, 502 ... concave, 600 ... third pass Cylinder, 601 ... Shaft, 602 ... Concave, 700 ... Second impression cylinder, 701 ... Shaft, 702 ... Concave, 800 ... Paper discharge part, 802 ... Concave

Claims (5)

An image carrier on which an electrostatic latent image is formed and rotatably supported on the housing, and a toner image based on the electrostatic latent image is developed;
A transfer cylinder that is rotatably supported by the housing and onto which the toner image developed on the image carrier is transferred;
A pressure drum that is rotatably supported by the housing and passes a recording medium between the transfer drum and the toner image on the transfer drum to the recording medium;
A ring electrode fixed concentrically with the axis of the transfer cylinder on the side end surface of the transfer cylinder;
A feeding electrode that feeds power in contact with the ring-shaped electrode in the axial direction of the transfer cylinder from the side opposite to the side end surface of the transfer cylinder;
An image forming apparatus comprising: The image forming apparatus according to claim 1, wherein the transfer cylinder is capable of contacting and separating from the image carrier and the impression cylinder. The image forming apparatus according to claim 1, further comprising a power supply electrode support member that supports the power supply electrode. The power supply electrode support member is supported by the housing,
In a state where the transfer cylinder is in contact with the image carrier and the impression cylinder, and in a state where the transfer cylinder is separated from the image carrier and the impression cylinder, the feeding electrode is The image forming apparatus according to claim 3, wherein the image forming apparatus is in contact with the ring-shaped electrode. The feeding electrode is separated from the position of the ring-shaped electrode in a state where the transfer cylinder is in contact with the image carrier and the impression cylinder, and the transfer cylinder is separated from the image carrier and the impression cylinder. The image forming apparatus according to claim 4, wherein the ring-shaped electrode is in contact with the ring-shaped electrode at a position where the position of the ring-shaped electrode intersects with the ring-shaped electrode.

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