JP5754661B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a copying machine, a facsimile, and a printer.

  Conventionally, a transfer member that forms a transfer nip by contacting a surface of an image carrier such as a photosensitive member or an intermediate transfer belt is provided, and a toner image on the image carrier is transferred to a recording member conveyed to the transfer nip. An image forming apparatus provided with a transfer device is known.

  The transfer apparatus includes a transfer member to which a transfer bias is applied, a separator that applies a separation bias to the recording member that has passed through the transfer nip to separate the recording member from the image carrier, and the bias is Power is supplied from a power supply device provided in the apparatus main body.

  In Patent Documents 1 and 2, when the transfer device is provided with a power receiving electrode that contacts the power supply electrode of the power supply device, and the transfer device that can be attached to and detached from the device main body is attached to the device main body, the power supply electrode and the power receiving electrode contact each other. An image forming apparatus to which power is supplied is described.

  Further, in the above image forming apparatus, in order to cope with various paper thicknesses, the transfer member is configured to be able to contact and separate from the surface of the image carrier, and the transfer member is pressed toward the image carrier by a pressing means such as a spring. ing. Patent Document 3 describes a transfer device provided with a cleaning blade that contacts the surface of the transfer member and scrapes off dirt such as toner adhering to the transfer member. In a transfer device provided with a cleaning blade, if only the transfer member is configured to be able to come in contact with and separate from the surface of the image carrier, the cleaning property is affected. For this reason, the transfer device is configured to be swingable with respect to the apparatus main body, and the transfer device is pressurized toward the image carrier by the pressurizing means.

  However, as described in Patent Document 3, when the transfer device is configured to be swingable, when the thick paper is conveyed to the transfer nip, the transfer device swings greatly, so that the power receiving electrode is separated from the power feeding electrode. There is a problem that a bias is not applied to a transfer member or the like. For this reason, in the configuration in which the transfer device is swung, the transfer device and the power supply device of the device main body are electrically connected via a harness. However, with this configuration, when the transfer device is taken out for maintenance or the like, it is necessary to remove the harness from the transfer device so that the harness does not get in the way. Further, when the transfer device is set in the image forming apparatus main body, it is necessary to connect the harness to the transfer device. As a result, there is a problem that the attaching / detaching operation of the transfer device becomes troublesome.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an image forming apparatus capable of maintaining the contact state between the power feeding electrode and the power receiving electrode even when the transfer device swings with respect to the apparatus main body. Is to provide.

To achieve the above object, the invention of claim 1 comprises an image carrier and a transfer member that forms a transfer nip in contact with the image carrier, and is swingably supported with respect to the apparatus main body. And a transfer device that can be attached to and detached from the apparatus main body, and a pressurizing unit that pressurizes the transfer device toward the image carrier while supporting the transfer device, conveys a recording member to the transfer nip, and an image forming apparatus for transferring a on the image bearing member toner image on the recording member in the transfer nip, the transfer device includes a power receiving electrode, the receiving electrode and in contact with the pressure means for supplying power to said transfer device feeding An electrode and a pressure roller that contacts the transfer device at a position different from the power supply electrode, and the power supply electrode is attached to the pressure means via an elastic member, or Transfer the receiving electrode to the above It is characterized in that attached to the location.
According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the power feeding electrode is disposed in a portion of the pressing unit that moves integrally with the transfer device.
According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the power receiving electrode and the power feeding electrode are separated from each other by removing the transfer device from the device main body, and the transfer device is attached to the device main body. By being mounted, the power receiving electrode and the power feeding electrode are in contact with each other.
According to a fourth aspect of the present invention, in the image forming apparatus according to the third aspect, the power receiving electrode is provided on a surface on the moving direction side of the transfer device when the transfer device is mounted on the apparatus main body. Is.
Further, it the invention of claim 5, in any one of the image forming apparatus according to claim 1 to 4, even without low, when the above-described feeding electrode and the receiving electrode are in contact, the elastic member is a compressed state It is characterized by.
According to a sixth aspect of the present invention, in the image forming apparatus according to the fifth aspect , a holding member for holding the elastic member in a compressed state is provided.
According to a seventh aspect of the present invention, in the image forming apparatus according to any one of the first to sixth aspects, the housing that holds the transfer device and the pressurizing unit and is supported so as to be drawable with respect to the apparatus main body is provided. It is characterized by having.
According to an eighth aspect of the present invention, in the image forming apparatus according to any one of the first to seventh aspects, the transfer device includes a conductive member downstream of the transfer nip in the recording member conveyance direction, and the conductive member and the above The power receiving electrode is electrically connected.
According to a ninth aspect of the present invention, in the image forming apparatus according to the eighth aspect , the conductive member is a recording member separating means for separating the recording member from the image carrier.
According to a tenth aspect of the present invention, in the image forming apparatus according to any one of the first to ninth aspects, the transfer member and the power receiving electrode are electrically connected.
According to an eleventh aspect of the present invention, in the image forming apparatus according to the tenth aspect , the image forming apparatus includes a plurality of gears, and includes a drive transmission device that transmits a driving force of a driving source to the transfer member, and is provided on the transfer member. The transfer device is rotatably supported on a gear shaft of a gear meshing with the transfer gear.
According to a twelfth aspect of the present invention, in the image forming apparatus according to the eleventh aspect , the transfer device includes a bearing fitting portion that is fitted to a cylindrical bearing provided on the gear shaft, and is wider than the gear shaft. And a notch portion connected to the bearing fitting portion.
According to a thirteenth aspect of the present invention, in the image forming apparatus according to any one of the first to twelfth aspects, a feeding electrode is provided at or near a portion of the pressure unit that supports the transfer device. .

  According to the present invention, by providing the power supply electrode to the pressurizing unit that pressurizes while supporting the transfer device, the contact state between the power supply electrode and the power reception electrode is maintained even when the transfer device swings with respect to the apparatus main body. It becomes possible to do. In other words, at least one part of the pressurizing unit as described above has a portion that moves integrally with the transfer device even when the transfer device swings. Therefore, if the power feeding electrode is provided in a portion that moves integrally with the transfer device of the pressurizing unit, the power feeding electrode is always brought into contact with the power receiving electrode of the transfer device even if the secondary transfer device swings. Can do. Accordingly, it is not necessary to electrically connect the transfer device and the power supply device with a harness, and the transfer device can be easily attached and detached.

1 is a schematic configuration diagram showing a copier according to an embodiment. FIG. 3 is an enlarged front view showing a secondary transfer nip and a surrounding configuration in the printer unit of the copier. FIG. 3 is an enlarged side view showing a peripheral configuration of the secondary transfer nip. FIG. 3 is an enlarged front view showing a configuration around a secondary transfer nip when a secondary transfer roller is separated from an intermediate transfer belt. FIG. 6 is a front view of the drawer housing when the secondary transfer unit is taken out from the drawer housing. FIG. 6 is a side view of the drawer housing when the secondary transfer unit is taken out from the drawer housing. FIG. 10 is an enlarged front view showing a secondary transfer nip and a surrounding configuration in a copying machine according to Modification 1. FIG. 9 is an enlarged front view showing a secondary transfer nip and its peripheral configuration in a copying machine according to Modification 2. FIG. 9 is an enlarged front view showing a secondary transfer nip and its peripheral configuration in a copying machine according to Modification 3.

Hereinafter, an embodiment in which the present invention is applied to a tandem type color copying machine (hereinafter simply referred to as a copying machine) as an image forming apparatus will be described.
FIG. 1 is a schematic configuration diagram illustrating a copying machine according to an embodiment. The copier includes a printer unit 100, a paper feeding unit 200, a scanner unit 300 attached on the printer unit 100, and an automatic document feeder (ADF) 400 attached on the scanner unit 300. ing.

  The printer unit 100 includes an endless belt-shaped intermediate transfer belt 21 as an image carrier. The intermediate transfer belt 21 is wound around the driving roller 22, the driven roller 23, and the secondary transfer counter roller 24 in a posture in which the side view is an inverted triangular shape, and is driven by rotation of the driving roller 22. It can be moved endlessly in the clockwise direction in the figure. Above the intermediate transfer belt 21, there are four image forming units 1C, M, Y, and K for forming C (cyan), M (magenta), Y (yellow), and K (black) toner images. Arranged along the belt moving direction.

  The image forming units 1C, M, Y, and K include photoreceptors 2C, M, Y, and K, developing units 3C, M, Y, and K, and photoreceptor cleaning devices 4C, M, Y, and K. Yes. The photoreceptors 2C, M, Y, and K abut on the intermediate transfer belt 21 to form primary transfer nips for C, M, Y, and K, respectively, and are driven in a counterclockwise direction in FIG. It can be driven to rotate. The developing units 3C, M, Y, and K are for developing the electrostatic latent image formed on the photoreceptors 2C, M, Y, and K with C, M, Y, and K toners. Further, the photoconductor cleaning devices 4C, M, Y, and K clean the transfer residual toner attached to the photoconductors 2C, M, Y, and K after passing through the primary transfer nip. In this printer, a tandem image forming unit 10 is configured by four image forming units 1C, M, Y, and K arranged in the belt moving direction.

  In the printer unit 100, an optical writing unit 15 is disposed above the tandem image forming unit 10. The optical writing unit 15 performs an optical writing process by optical scanning on the surfaces of the photoreceptors 2C, M, Y, and K that are rotationally driven counterclockwise in the drawing to form an electrostatic latent image. Is. Prior to the optical writing process, the surfaces of the photoreceptors 2C, M, Y, and K are respectively charged in one way by the one-like charging unit of the image forming units 1C, M, Y, and K.

  The transfer unit 20 including the intermediate transfer belt 21 has primary transfer rollers 25C, M, Y, and K inside the loop of the intermediate transfer belt 21. These primary transfer rollers 25C, M, Y, and K press the intermediate transfer belt 21 toward the photoreceptors 2C, M, Y, and K on the back side of the primary transfer nip for C, M, Y, and K. Yes.

  Below the intermediate transfer belt 21, a secondary transfer roller 30 as a contact member is disposed. The secondary transfer roller 30 abuts on the intermediate transfer belt 21 around the secondary transfer counter roller 24 from the belt front surface side to form a secondary transfer nip. A recording sheet is fed into the secondary transfer nip at a predetermined timing. Then, the four-color superimposed toner image on the intermediate transfer belt 21 is collectively transferred to the recording sheet at the secondary transfer nip.

  The scanner unit 300 reads image information of a document placed on the contact glass 301 by the reading sensor 302 and sends the read image information to the control unit of the printer unit 100. A control unit (not shown) as a control unit including a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and the like performs optical writing of the printer unit 100 based on image information received from the scanner unit 300. The light source such as a laser diode or LED in the unit 15 is controlled to emit laser writing light for C, M, Y, K, and the photoconductors 2C, M, Y, K are optically scanned. By this optical scanning, electrostatic latent images are formed on the surfaces of the photoreceptors 2C, M, Y, and K, and the latent images are developed into C, M, Y, and K toner images through a predetermined development process.

  A paper feed unit 200 includes paper cassettes 202 arranged in multiple stages in the paper bank 201, a paper feed roller 203 that feeds out recording sheets from the paper feed cassette 202, and separates the sent out recording sheets into a paper feed path 204. A separation roller 205 that guides the sheet, and a conveyance roller 206 that conveys the recording sheet to the sheet feeding path 99 of the printer unit 100 are provided.

  In addition to the paper feed unit 200, manual paper feed is also possible, and the manual feed tray 98 for manual feed and the recording sheets on the manual feed tray 98 are separated one by one toward the manual feed path 97. A separating roller 96 is also provided. In the printer unit 100, the manual paper feed path 97 joins the paper feed path 99.

  Near the end of the paper feed path 99, a registration roller pair 95 is disposed. The registration roller pair 95 sandwiches the recording sheet conveyed in the paper feed path 99 between the rollers and then feeds it toward the secondary transfer nip at a predetermined timing.

  In the copying machine according to the embodiment, when copying a color image, an original is set on the original table 401 of the ADF 400, or the ADF 400 is opened and the original is set on the contact glass 301 of the scanner unit 300. Hold the document by closing it. Then, a start switch (not shown) is pressed. Then, when the document is set on the ADF 400, the document is conveyed onto the contact glass 301. Thereafter, the scanner unit 300 starts driving, and the first traveling body 303 and the second traveling body 304 start traveling along the document surface. Then, the light emitted from the light source by the first traveling body 303 is emitted on the document surface, and the obtained reflected light is folded and directed to the second traveling body 304. The folded light is further folded by the mirror of the second traveling body 304 and then enters the reading sensor 302 through the imaging lens 305. Thereby, the content of the original is read.

  When the printer unit 100 receives the image information from the scanner unit 300, the printer unit 100 feeds a recording sheet having a size corresponding to the image information to the paper feed path 99. Along with this, the drive roller 22 is rotationally driven by a drive motor (not shown) to move the intermediate transfer belt 21 endlessly in the clockwise direction in the drawing. At the same time, after starting rotation of the photoconductors 2C, M, Y, and K of the image forming units 1C, M, Y, and K, a one-way charging process, an optical writing process for the photoconductors 2C, M, Y, and K are performed. Perform development processing. The C, M, Y, and K toner images formed on the surfaces of the photoreceptors 2C, M, Y, and K by these processes are sequentially overlapped at the C, M, Y, and K primary transfer nips to be intermediate. Primary transfer is performed on the transfer belt 21 to form a four-color superimposed toner image.

  In the paper supply unit 200, one of the paper supply rollers 203 is selectively rotated according to the recording sheet size, and the recording sheet is sent out from one of the three paper supply cassettes 202. The fed recording sheets are separated one by one by the separation roller 4205 and introduced into the paper feed path 206, and then sent to the paper feed path 99 in the printer unit 100 via the transport roller 206. When the manual feed tray 98 is used, the paper feed roller of the tray is driven to rotate, and the recording sheet on the tray is fed to the manual paper feed path 97 while being separated by the separation roller 96 and is fed to the end of the paper feed path 99. To the vicinity. In the vicinity of the end of the paper feed path 99, the recording sheet stops by abutting the leading edge against the registration roller pair 95. Thereafter, when the registration roller pair 95 is rotationally driven at a timing that can synchronize with the four-color superimposed toner image on the intermediate transfer belt 21, it is fed into the secondary transfer nip and is in close contact with the four-color superimposed toner image on the belt. . Then, the secondary transfer is performed collectively on the recording sheet due to the influence of the nip pressure and the transfer electric field.

  The recording sheet on which the four-color superimposed toner image has been secondarily transferred at the secondary transfer nip is fed into the fixing device 71 by the paper transport belt 70. Then, when the fixing device 71 is sandwiched in the fixing nip between the pressure roller 72 and the fixing belt 73, the four-color superimposed toner image is fixed on the surface by pressure or heat treatment. The recording sheet on which the color image has been formed in this manner is stacked on a discharge tray 75 outside the apparatus via a discharge roller pair 74. When an image is also formed on the other side of the recording sheet, the recording sheet is discharged from the fixing device 71 and then the path is switched by the switching claw 76 so that the recording sheet is sent to the sheet reversing device 75. It is done. Then, after being turned upside down, it is returned to the registration roller pair 95 again, and then goes through the secondary transfer nip and the fixing device 71 again.

  After passing through the secondary transfer nip, the belt cleaning device 26 contacts the surface of the intermediate transfer belt 21 before entering the C primary transfer nip where the primary transfer process is the most upstream of the four colors. ing. This belt cleaning device 26 cleans the transfer residual toner adhering to the belt surface.

2 is a front view showing a secondary transfer nip and its surrounding configuration in the printer unit 100 of the copying machine according to the embodiment, and FIG. 3 is a secondary transfer nip and its surrounding configuration in the printer unit 100 of the copying machine. FIG.
In the figure, a secondary transfer counter roller 24 that partially wraps the belt around its peripheral surface inside the loop of the intermediate transfer belt 21 backs up the deformable intermediate transfer belt 21 on its peripheral surface. It plays the role of maintaining the shape along a certain curvature. A secondary transfer roller 30 is in contact with the secondary transfer counter roller 24 on the intermediate transfer belt 21 from the belt front surface side to form a secondary transfer nip.

  In this copier, the secondary transfer unit 40 and the secondary transfer unit 40 are transmitted to the secondary transfer roller 30 by a pressurizing mechanism 55 that serves as a pressurizing unit that pressurizes the secondary transfer unit 40 toward the intermediate transfer belt as an image carrier. A drive transmission mechanism 39 (see FIG. 3) as a drive transmission device, a registration roller pair 95, and the like are held, and a drawer housing 28 is supported so as to be freely drawn out from the apparatus main body. Slide rails 29 are provided on both side surfaces of the drawer housing 28, and are configured to be able to be pulled out from the apparatus main body to the front side.

  The secondary transfer unit 40 as a transfer device includes a secondary transfer roller 30, a cleaning blade 47, a lubricant application device 44, a separation discharger 32, and the like. The secondary transfer roller 30, the cleaning blade 47, the lubricant application device 44, and the separation discharger 32 are held by a roller unit holder 43.

  The roller unit holding body 43 is held on a rotating shaft 33 for transmitting a rotational driving force to the secondary transfer roller 30 via a roller unit support bearing 34, and is configured to be rotatable about the roller unit support bearing 34. Has been. As a result, the secondary transfer unit 40 is supported to be swingable with respect to the apparatus main body.

  The secondary transfer roller as a transfer member is rotatably held by the roller unit holding body 43 via a bearing. In the present copying machine, the secondary transfer roller 30 applies a secondary transfer bias having the same polarity as the toner to the secondary transfer counter roller 24 on one side grounded via a pressure roller 54. As a result, a secondary transfer electric field for electrostatically moving the toner from the secondary transfer counter roller 24 side to the secondary transfer roller 30 side is formed in the secondary transfer nip between the two rollers.

  The toner on the belt adheres to the surface of the secondary transfer roller 30 that is in contact with the front surface of the intermediate transfer belt 21 that carries the toner image. If this adhering toner is left as it is, it is transferred to the back surface of the recording sheet at the secondary transfer nip, and so-called back dirt is generated. Therefore, the secondary transfer unit 40 includes a cleaning blade 47 and mechanically removes toner from the surface of the secondary transfer roller 30 by bringing the edge of the cleaning blade 47 into contact with the surface of the secondary transfer roller 30. ing.

  Further, the secondary transfer unit 40 includes a lubricant application device 44 and applies a lubricant to the surface of the secondary transfer roller 30. The lubricant application device 44 includes a lubricant application brush roller 42, a solid lubricant 41, a lubricant presser (not shown) that presses the solid lubricant 41 against the lubricant application brush roller 42, and the like. The lubricant application brush roller 42 applies to the secondary transfer roller 30 while scraping the solid lubricant 41 made of a zinc stearate lump or the like. By applying the lubricant in this way, an increase in rotational load due to contact between the cleaning blade 47 and the secondary transfer roller 30 is suppressed. In addition, occurrence of blade edge entrainment is also suppressed.

  Further, the secondary transfer unit 40 includes a separation discharger 32 made of a conductive member. The separation discharger 32 is disposed downstream of the secondary transfer roller 30 in the recording sheet conveyance direction. The separation discharger 32 is provided with a plurality of protrusions over its longitudinal direction, and an AC bias is applied. A power receiving electrode 65 provided on the lower surface of the roller unit holder 43 is connected to the separation discharger 32.

Further, since the load that impedes the rotation is applied to the secondary transfer roller 30 due to the contact of the cleaning blade 47, the secondary transfer roller 30 cannot be driven and rotated by the rotation of the intermediate transfer belt 21. For this reason, the secondary transfer roller 30 is rotationally driven.
As shown in FIG. 3, a drive transmission mechanism 39 serving as a drive transmission device that transmits a rotational driving force to the secondary transfer roller 30 is provided at the left end portion (the rear end portion of the apparatus) in the drawing. The drive transmission mechanism 39 includes a driven gear 36, a transfer gear 37, and the like. The driven gear 36 is fixed to a rotating shaft 33 that is rotatably supported by the drawer housing 28 via a bearing. A coupling 35 is attached to the end of the rotary shaft 33 on the back side of the apparatus, and engages with a coupling of a drive shaft connected to a roller drive motor, which is a drive source (not shown). A rotational driving force of a roller driving motor (not shown) is transmitted to the driven gear 36 and the transfer gear 37 via the coupling 35, and the secondary transfer roller 30 is rotationally driven.

  As shown in FIG. 2, a pressurizing mechanism 55 serving as a pressurizing unit for pressurizing the roller unit holder 43 to the intermediate transfer belt 21 is disposed below the secondary transfer unit 40. As shown in FIG. 3, the pressurizing mechanism 55 is disposed on the front side and the back side of the apparatus. The pressure mechanism 55 includes a pressure lever 52, a pressure roller 54, a pressure spring 45, and the like that can be rotated around a pressure lever rotation shaft 53. One end of the pressure lever 52 is rotatably supported by the pressure lever rotation shaft 53, and one end of the pressure spring 45 is fixed to the other end. The other end of the pressure spring 45 is fixed to a spring receiver 27 fixed to the side surface of the drawer housing 28. A pressure roller 54 that is in contact with the lower surface of the roller unit holder 43 of the secondary transfer unit 40 is attached to a substantially central portion of the pressure lever 52. The other end (right side in the figure) of the pressure lever 52 is pushed up by a pressure spring 45 with an upward force in the figure. As a result, the pressure lever 52 rotates counterclockwise in the figure, and the pressure roller 54 attached to the pressure lever 52 pressurizes the secondary transfer unit 40. Due to this applied pressure, the secondary transfer unit 40 is given a force to rotate in the counterclockwise direction in the drawing around the roller unit support bearing 34. As a result, the secondary transfer roller 30 of the secondary transfer unit 40 is pressed against the intermediate transfer belt 21 to form a secondary transfer nip.

  Further, the drawer housing 28 is provided with a separation mechanism 56 that is a separation means for separating the secondary transfer roller 30 from the intermediate transfer belt 21 when a paper jam or the like occurs. The separation mechanism 56 includes a camshaft 50 rotatably supported by a drawer housing 28 via a bearing, a contact / separation cam 51 fixed to the camshaft 50, and a cam drive motor 46 that rotationally drives the camshaft 50 (FIG. 3). Reference) etc. By rotating the contact / separation cam 51 to contact the pressure lever 52, the pressure lever 52 rotates around the pressure lever rotation shaft 53 in the clockwise direction as shown in FIG. The pressing force of the pressure spring 45 is received by the contact / separation cam 51. For this reason, the applied pressure to the secondary transfer unit 40 is eliminated, and the secondary transfer unit 40 rotates around the roller unit support bearing 34 in the clockwise direction in FIG. Move while touching. As a result, the secondary transfer roller 30 held by the roller unit holder 43 is separated from the intermediate transfer belt 21.

  In addition, a power supply device 66 for supplying an AC bias to the separation discharger 32 is disposed on the pressure lever 52 on the front side. The power feeding device 66 includes a power feeding electrode 61 made of a cylindrical conductor in contact with the power receiving electrode 65 of the secondary transfer unit 40, and a conductive device connected via a harness 64 to a power supply device 260 provided on the bottom surface of the drawer housing 28. It includes a plate 62, a conductive compression coil spring 63 as an elastic member disposed between the conductive plate 62 and the power supply electrode 61, a resin holder 60 as a holding member for holding them. The resin holder 60 is provided with a hole into which the cylindrical power supply electrode 61 is inserted, and the power supply electrode 61 is inserted into the hole of the resin holder 60. The compression coil spring 63 is longer than the height of the resin holder 60 and is held in a compressed state in the resin holder 60. Therefore, due to the elasticity of the compression coil spring 63, the power feeding electrode 61 is pressed toward the power receiving electrode 65 and is pressed against the power receiving electrode 65. As a result, the AC bias is stably supplied to the separating discharger 32. The AC bias fed from the power supply device 260 to the conductive plate 62 via the harness 64 is fed to the power receiving electrode 65 via the compression coil spring 63 and the power feeding electrode 61 and fed from the power receiving electrode 65 to the separation discharger 32. Is done.

  Electric discharge is generated from the protruding portion of the separating discharger 32 toward the back surface of the recording sheet portion immediately after passing the secondary transfer nip, and the recording sheet is discharged. As a result, the electrostatic attraction force of the recording sheet to the surface of the intermediate transfer belt 21 decreases, and the recording sheet is separated from the intermediate transfer belt 21.

  When the recording sheet is conveyed to the transfer nip and the secondary transfer roller 30 receives a force in a direction away from the intermediate transfer belt 21 from the recording sheet, the secondary transfer unit 40 is rotated clockwise around the rotation shaft 33 in the drawing. A force to rotate is working. As a result, the secondary transfer unit 40 presses the pressure roller 54, and the secondary transfer unit 40 rotates clockwise in the drawing together with the pressure lever 52 against the pressure force of the pressure spring 45. . As a result, the secondary transfer roller 30 is separated from the intermediate transfer belt 21 by the thickness of the paper, and the recording sheet passes through the secondary transfer nip. At this time, the power supply electrode 61 provided on the pressure lever 52 that rotates integrally with the secondary transfer unit 40 also rotates clockwise in the drawing, and therefore the power supply electrode 61 and the power reception electrode 65. The connection state with can be maintained. As a result, even when thick paper or the like is conveyed to the secondary transfer nip and the secondary transfer unit 40 swings greatly, the connection between the power supply electrode 61 and the power reception electrode 65 can be maintained, and the separation can be performed stably. An AC bias can be applied to the discharger 32, and good separation performance can be maintained.

  Further, since the rotation center of the secondary transfer unit 40 is the rotation shaft 33 to which the driven gear 36 is fixed, when the secondary transfer unit 40 is rotated, the rotation center of the secondary transfer roller 30 is rotated. The distance relationship with the shaft 33 is constant. Therefore, even if the secondary transfer unit 40 rotates, the meshing between the driven gear 36 and the transfer gear 37 fixed to the shaft of the secondary transfer roller 30 can be maintained. Therefore, even when the secondary transfer unit 40 swings, the rotational driving force can be transmitted to the secondary transfer roller 30 and the secondary transfer roller 30 can be driven to rotate.

  Further, the pressure roller 54 is made of a rigid body and does not deform even when it receives a pressing force from the secondary transfer unit 40. Therefore, the distance from the lower surface of the secondary transfer unit 40 to the pressure lever 52 is small. Fluctuation can be suppressed. As a result, the feeding electrode 65 can be prevented from being pushed in by the secondary transfer unit 40 when the secondary transfer unit swings, and a stable contact state can be maintained. Further, the power supply electrode 61 is disposed in the vicinity of the pressure roller 54 that supports the secondary transfer unit 40, so that the power supply device 66 of the pressure lever 52 is attached when the secondary transfer unit 40 swings. And the lower surface of the secondary transfer unit 40 can be suppressed, and the contact state between the power feeding electrode and the power receiving electrode can be maintained satisfactorily.

Next, attachment / detachment of the secondary transfer unit 40 will be described.
When taking out the secondary transfer unit 40 from the drawer housing 28, first, the drawer housing 28 is pulled out from the apparatus main body. Next, it is necessary to remove the two roller unit support bearings 34 fitted to the roller unit holder 43. Since the roller unit support bearing 34 is fixed to the pressure lever rotating shaft 53 with a screw 38 as shown in FIG. 3, the screw 38 is first removed. The reason why the roller unit support bearing 34 is fixed to the pressure lever rotating shaft 53 is that the roller unit support bearing 34 is a cylindrical member made of a slidable resin material. The bearing 34 may rotate together with the rotation of the rotary shaft 33, and may not perform the function of the bearing. For this reason, in this copying machine, the roller unit support bearing 34 is fixed to the pressure lever rotating shaft 53 that does not rotate. When the screw 38 is removed, each roller unit support bearing 34 is slid in the direction of the arrow shown in FIG. Thereby, the fitting between the secondary transfer unit 40 and the roller unit support bearing 34 is released. As shown in FIG. 2, the roller unit holding body 43 has a cutout portion in which a lower portion of a cylindrical fitting portion into which the roller unit support bearing 34 is fitted is cut out. The width of the notch is shorter than the outer diameter of the bearing portion of the roller unit support bearing 34 and longer than the diameter of the rotating shaft 33. As a result, as shown in FIGS. 5 and 6, the secondary transfer unit 40 can be attached and detached by lifting it upward without removing the rotating shaft 33. Further, by making this notch width smaller than the roller unit support bearing 34, the roller unit support bearing 34 is inserted into the fitting portion of the secondary transfer unit 40 and fitted, whereby the secondary transfer unit 40 is pulled out. Positioned relative to the housing 28. Thereby, the positional relationship between the secondary transfer roller 30 and the secondary transfer counter roller 24 can be set to a predetermined relationship, and stable transferability can be obtained.

  Further, a power receiving electrode 65 is provided on the lower surface of the secondary transfer unit 40 that is a surface on the moving direction side of the secondary transfer unit 40 when the secondary transfer unit 40 is attached to the apparatus main body. For this reason, if the secondary transfer unit 40 is moved upward to remove it from the apparatus main body, the power receiving electrode 65 and the power feeding electrode 61 are separated from each other, and the secondary transfer unit 40 is moved downward to be mounted on the apparatus main body. As a result, the power receiving electrode 65 and the power feeding electrode 61 come into contact with each other. In this way, the electrical connection and release of the power receiving electrode 65 and the power feeding electrode 61 are performed in conjunction with the attaching / detaching operation of the secondary transfer unit 40, so that the harness and the members of the secondary transfer unit 40 are used. The attachment / detachment work of the secondary transfer unit 40 can be simplified as compared with the case of electrical connection.

  Further, as shown in FIG. 5, when the secondary transfer unit 40 is pulled out and removed from the housing 28, the tip of the power supply electrode 61 is located above the pressure roller 52. When the secondary transfer unit 40 is attached to the drawer housing 28, the power supply electrode 61 is pushed downward by the secondary transfer unit 40, and the compression coil spring 63 is compressed. Accordingly, even if an error occurs in the distance from the pressure lever 52 to the secondary transfer unit 40 due to a manufacturing error of the pressure roller 52, a manufacturing error of the pressure lever 52, or the like, the power feeding electrode 61 is securely connected to the power receiving electrode 65. It can be made to contact. Further, even when the distance between the portion where the power supply device 66 of the pressure lever 52 is attached and the lower surface of the secondary transfer unit 40 varies due to the swinging of the secondary transfer unit 40, the power supply electrode 61 is connected to the resin holder. It can slide with respect to 60 and can maintain the contact state with the receiving electrode 65.

  In this copying machine, the secondary transfer roller 30 is grounded via the pressure roller 52. However, if the secondary transfer roller 30 can be grounded via another member, the pressure roller 52 is supplied with power. An electrode 61 may be provided. Since the pressure roller 52 is a place that supports the secondary transfer unit 40, the pressure roller 52 moves together with the secondary transfer unit 40 while being in contact with the secondary transfer unit 40. Therefore, by providing the feeding electrode 61 on the pressure roller 52, the contact state between the feeding electrode 61 and the power receiving electrode 65 can be maintained.

  Next, a modified example of the copying machine will be described.

[Modification 1]
First, the copying machine of Modification 1 will be described.
FIG. 7 is a front view showing the secondary transfer nip and the surrounding configuration in the printer unit 100 of the copying machine of the first modification.
As shown in FIG. 7, in the first modification, the power receiving unit of the secondary transfer unit 40 includes a power receiving electrode 65 made of a cylindrical conductive member, and a conductive plate 62 ′ connected to the separation discharger 32. The conductive compression coil spring 63 ′ disposed between the conductive plate 62 ′ and the power receiving electrode 65, and the resin holder 60 ′ that holds them. The power supply electrode 61 connected to the power supply device 260 via the harness 64 is attached to the front pressure lever 52.

  As described above, even in a configuration in which the power receiving electrode 65 is pressed toward the power feeding electrode 61 by the compression coil spring 63 ′ and the power receiving electrode 65 is pressed against the power feeding electrode 61, the recording sheet is conveyed to the secondary transfer nip and the secondary transfer unit 40. Even if the oscillates, the contact state between the power receiving electrode 65 and the power feeding electrode 61 is maintained, and the power feeding electrode 61 moves together with the secondary transfer unit 40. Thereby, an AC bias can be supplied to the power receiving electrode 65 stably.

[Modification 2]
Next, a copying machine of Modification 2 will be described.
FIG. 8 is a front view showing the secondary transfer nip and its surrounding configuration in the printer unit 100 of the copying machine of the second modification.
As shown in FIG. 8, in the second modification, the secondary transfer roller 30 is connected to the power receiving electrode 65. In the copier according to the second modification, the secondary transfer bias is supplied to the conductive plate 62 from the power supply device 260 disposed at the bottom of the drawer housing 28 via the harness 64. Then, power is supplied to the power receiving electrode 65 via the compression coil spring 63 and the power supply electrode 61, and the secondary transfer bias is supplied from the power receiving electrode 65 to the secondary transfer roller 30.

[Modification 3]
Next, a copying machine of Modification 3 will be described.
FIG. 9 is a front view showing the secondary transfer nip and the surrounding configuration in the printer unit 100 of the copying machine of the third modification.
In the third modification, the secondary transfer unit 40 is pressurized by the power feeding device 66. That is, in this configuration, the compression coil spring 63 held by the resin holder 60 also functions as a pressurizing unit that presses the secondary transfer unit 40 toward the intermediate transfer belt 21.

  In the third modification, when the recording sheet is conveyed to the secondary transfer nip and the secondary transfer unit 40 swings, the compression coil spring 63 is compressed, and the feeding electrode 61 moves together with the secondary transfer unit 40. Accordingly, the contact between the power supply electrode 61 and the power receiving electrode 65 provided in the secondary transfer unit 40 can be always maintained, and the secondary transfer bias can be stably supplied to the secondary transfer roller 30. .

  As described above, according to the image forming apparatus of the present embodiment, the secondary transfer roller that is a transfer member that forms a transfer nip by contacting the intermediate transfer belt 21 that is an image carrier is provided, and is swingably supported with respect to the apparatus main body. And a secondary transfer unit which is a transfer device detachable from the apparatus main body. In addition, a pressurizing mechanism 55 serving as a pressurizing unit that pressurizes the intermediate transfer belt while supporting the secondary transfer unit is provided. A power supply electrode 65 that contacts the power receiving electrode 65 provided in the secondary transfer unit 40 and that supplies power to the secondary transfer unit 40 is provided in the pressurizing mechanism 55. The pressurizing mechanism that supports and pressurizes the secondary transfer unit is a portion that moves integrally with the secondary transfer unit when the secondary transfer unit swings (in this embodiment, the pressurizing lever 52 and the pressurizing mechanism). There is a pressure roller 54). Therefore, by providing the power supply electrode in that portion, the contact state between the power reception electrode and the power supply electrode can be maintained even when the secondary transfer unit is swung. As a result, even if the secondary transfer unit is swung, electricity from the power supply device can be stably supplied to the secondary transfer unit.

  In this embodiment, when the secondary transfer unit is taken out from the apparatus main body, the power receiving electrode 65 and the power feeding electrode 61 are separated from each other, and when the secondary transfer unit is attached to the apparatus main body, the power receiving electrode 65 and the power feeding electrode 61 are separated. Are configured to contact each other. Specifically, a power receiving electrode is provided on the lower surface of the secondary transfer unit, which is the moving direction side surface of the secondary transfer unit when the secondary transfer unit is attached to the apparatus main body. Thereby, the removal operation of the secondary transfer unit can be simplified as compared with the case where the secondary transfer unit is removed from the apparatus main body after the nine electrodes and the power receiving electrode are separated from each other. Further, when the secondary transfer unit is mounted on the apparatus main body, the work of mounting the secondary transfer unit on the apparatus main body can be simplified as compared with the case where the power feeding electrode and the power receiving electrode are brought into contact with each other.

  Further, by attaching the power supply electrode to the pressurizing mechanism via the elastic member, the power supply electrode can be elastically brought into contact with the power reception electrode. In particular, when the power supply electrode and the power reception electrode are in contact with each other, the elastic member is brought into a compressed state, whereby the power supply electrode can be pressed against the power reception electrode, and the secondary transfer unit can be electrically connected to the secondary transfer unit. Can be fed. Further, when the secondary transfer unit swings, even if the power receiving electrode is displaced in a direction away from the power feeding electrode, the power feeding electrode can follow the displacement of the power receiving electrode, and the contact state can be maintained.

  Further, by providing a resin holder that is a holding member that holds the elastic member in a compressed state, the power feeding electrode can be stably pressurized toward the power receiving electrode.

  In addition, by holding the secondary transfer unit 40 and the pressure mechanism 55 and including a drawer housing 28 that is supported so as to be able to be pulled out from the apparatus main body, the drawer housing can be pulled out from the apparatus main body. Thus, the secondary transfer unit can be exposed. Thereby, the secondary transfer unit can be easily attached and detached.

  Further, the secondary transfer unit is provided with a separation discharger as a recording member separation means made of a conductive member on the downstream side in the transport direction with respect to the recording paper from the secondary transfer nip, and electrically connects the separation discharger and the power receiving electrode. Therefore, even if the secondary transfer unit swings, power can be supplied to the separation discharger. Accordingly, the recording sheet after passing through the secondary transfer nip can be discharged to discharge the recording sheet, and the recording sheet can be satisfactorily separated from the intermediate transfer belt.

  Further, the secondary transfer roller and the power receiving electrode may be electrically connected. Thereby, even if the secondary transfer unit swings, the secondary transfer bias can be applied to the secondary transfer roller.

  Further, the secondary transfer unit is rotatably supported on a rotary shaft 33 which is a gear shaft to which a driven gear which is a gear meshing with a transfer gear provided on the secondary transfer roller is fixed. Even if the roller swings, the meshing between the transfer gear and the driven gear can be maintained, and the secondary transfer roller can be driven to rotate.

  In addition, the transfer device includes a bearing fitting portion that fits into a cylindrical bearing provided on the rotating shaft, and a notch portion that is wider than the rotating shaft and connected to the bearing fitting portion. Thereby, since the rotating shaft can be positioned at the bearing fitting portion through the notch portion, the transfer device can be attached to and detached from the apparatus main body without removing the rotating shaft.

  In addition, a power feeding electrode is provided at or near the location where the secondary transfer unit of the pressurizing mechanism is supported. The location where the secondary transfer unit of the pressure mechanism is supported is the location where the secondary transfer unit contacts and moves together with the secondary transfer unit when the secondary transfer unit swings. Therefore, the connection between the power feeding electrode and the power receiving electrode can be maintained by providing the power feeding electrode at or near the location where the secondary transfer unit of the pressure mechanism is supported.

21: Intermediate transfer belt 28: Drawer housing 30: Secondary transfer roller 32: Separating discharger 33: Rotating shaft 34: Roller unit support bearing 39: Drive transmission mechanism 40: Secondary transfer unit 45: Pressure spring 46: Cam drive motor 50: cam shaft 51: contact / separation cam 52: pressure lever 53: pressure lever rotating shaft 54: pressure roller 55: pressure mechanism 56: separation mechanism 60: resin holder 61: power supply electrode 62: conductive Plate 63: Compression coil spring 64: Harness 65: Power receiving electrode 66: Power feeding device 260: Power supply device

JP 2006-139078 A Japanese Patent No. 4076427 JP 2007-328275 A

Claims (13)

An image carrier;
A transfer device that includes a transfer member that forms a transfer nip in contact with the image carrier, is supported swingably with respect to the apparatus main body, and is detachable from the apparatus main body;
A pressurizing unit that pressurizes the transfer device toward the image carrier while supporting the transfer device;
In the image forming apparatus for conveying the recording member to the transfer nip and transferring the toner image on the image carrier to the recording member in the transfer nip.
The transfer device includes a power receiving electrode,
A power supply electrode that contacts the power receiving electrode and supplies power to the transfer device, and a pressure roller that contacts the transfer device at a position different from the power supply electrode ;
An image forming apparatus, wherein the power feeding electrode is attached to the pressurizing unit via an elastic member, or the power receiving electrode is attached to the transfer device via an elastic member . The image forming apparatus according to claim 1.
An image forming apparatus, wherein the power supply electrode is disposed in a portion of the pressurizing unit that moves together with the transfer device. The image forming apparatus according to claim 1 or 2,
The power receiving electrode and the power feeding electrode are separated from each other by removing the transfer device from the apparatus main body, and the power receiving electrode and the power feeding electrode are brought into contact with each other by attaching the transfer device to the apparatus main body. An image forming apparatus. The image forming apparatus according to claim 3.
An image forming apparatus, wherein the power receiving electrode is provided on a surface on the moving direction side of the transfer device when the transfer device is attached to the apparatus main body. The image forming apparatus according to claim 1 ,
Even without low, when the above-described feeding electrode and the receiving electrode is in contact with the image forming apparatus, wherein said elastic member is a compressed state. The image forming apparatus according to claim 5 .
An image forming apparatus comprising a holding member for holding the elastic member in a compressed state. The image forming apparatus according to claim 1 to 6,
An image forming apparatus, comprising: a housing that holds the transfer device and the pressurizing unit and is supported so as to be drawable with respect to the apparatus main body. The image forming apparatus according to claim 1 to 7,
The transfer device includes a conductive member on the downstream side of the transfer nip in the recording member conveyance direction,
An image forming apparatus, wherein the conductive member and the power receiving electrode are electrically connected. The image forming apparatus according to claim 8 .
An image forming apparatus, wherein the conductive member is a recording member separating unit that separates the recording member from the image carrier. An image forming apparatus characterized in that electrically connecting the transfer member and the power receiving electrode in any of the image forming apparatus according to claim 1 to 9. The image forming apparatus according to claim 10 .
A drive transmission device having a plurality of gears and transmitting a drive force of a drive source to the transfer member;
An image forming apparatus, wherein the transfer device is rotatably supported on a gear shaft of a gear meshing with a transfer gear provided on the transfer member. The image forming apparatus according to claim 11 .
The transfer device includes a bearing fitting portion that fits into a cylindrical bearing provided on the gear shaft, and a notch portion that is wider than the gear shaft and connected to the bearing fitting portion. An image forming apparatus. The image forming apparatus according to claim 1 to 12,
An image forming apparatus characterized in that a feeding electrode is provided at or near a portion of the pressing means that supports the transfer device.

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