JP2019207368A - Image forming apparatus - Google Patents

Abstract

To provide an image forming apparatus that can stably form an image on a medium.SOLUTION: An image forming apparatus comprises: a developing unit that attaches a toner to electrostatic latent images; a supporting member that is separated from the developing unit; a transfer unit that is supported by the supporting member, transfers the toner attached to the electrostatic latent images to a medium conveyed in a conveyance direction, and circles with respect to the support member on a pivot extending in a direction intersecting the conveyance direction; and a separation member that is arranged on the downstream side of the transfer unit in the conveyance direction, separates the medium to which the toner is transferred from the transfer unit, and approaches or retreats from the transfer unit in conjunction with the circling of the transfer unit.SELECTED DRAWING: Figure 8

Description

  The present invention relates to an image forming apparatus that transfers toner onto a medium.

  Electrophotographic image forming apparatuses are widely used. This is because a clear image can be obtained in a short time compared to an image forming apparatus of another method such as an ink jet method.

  An electrophotographic image forming apparatus (hereinafter simply referred to as an “image forming apparatus”) includes a developing unit for attaching toner to an electrostatic latent image, and transferring the toner attached to the electrostatic latent image to a medium. A transfer unit.

  Since the configuration of the image forming apparatus affects the image forming operation, various proposals have been made regarding the configuration of the image forming apparatus. Specifically, when the medium is adsorbed on the image carrier, a film-like separation member is brought close to the image carrier in order to separate the medium from the image carrier (see, for example, Patent Document 1). .)

JP 2014-199468 A

  Various proposals have been made regarding the configuration of the image forming apparatus, but there is still room for improvement because the image forming operation is not sufficient.

  The present invention has been made in view of such problems, and an object thereof is to provide an image forming apparatus capable of stably forming an image on a medium.

  An image forming apparatus according to an embodiment of the present invention includes a developing unit that attaches toner to an electrostatic latent image, a support member that is separated from the developing unit, and a medium that is supported by the support member and is conveyed in the conveyance direction. A transfer unit that transfers toner adhering to the electrostatic latent image to the support member and that rotates with respect to a support member about a rotation axis that extends in a direction that intersects the conveyance direction. And a separation member that is disposed on the downstream side and separates the medium onto which the toner has been transferred from the transfer unit, and approaches or retracts the transfer unit in conjunction with the rotation of the transfer unit.

  According to the image forming apparatus of one embodiment of the present invention, the separation member approaches or retracts from the transfer unit in conjunction with the rotation of the transfer unit, so that an image can be stably formed on the medium.

1 is a plan view schematically illustrating a configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a perspective view illustrating a configuration of a transfer unit illustrated in FIG. 1. FIG. 2 is an enlarged perspective view illustrating a part of the configuration of the image forming apparatus illustrated in FIG. 1. FIG. 2 is a plan view schematically showing an enlarged part of the configuration of the image forming apparatus shown in FIG. 1. 2 is a perspective view illustrating a configuration of an image forming apparatus when a transfer unit is mounted. FIG. FIG. 10 is a perspective view illustrating another configuration of the image forming apparatus when the transfer unit is mounted. FIG. 10 is a perspective view illustrating still another configuration of the image forming apparatus when the transfer unit is mounted. FIG. 3 is a perspective view illustrating a configuration of an image forming apparatus when the transfer unit is detached. FIG. 10 is a perspective view illustrating another configuration of the image forming apparatus when the transfer unit is detached. FIG. 10 is a perspective view illustrating still another configuration of the image forming apparatus when the transfer unit is detached. FIG. 9 is a plan view schematically illustrating an enlarged part of the configuration of the image forming apparatus illustrated in FIG. 8. FIG. 10 is a perspective view for explaining a transfer operation of the transfer unit.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. The order of explanation is as follows.

1. Image forming apparatus 1-1. Overall configuration 1-2. Desorption mechanism of transfer unit 1-3. Operation 1-4. Action and effect Modified example

<1. Image forming apparatus>
An image forming apparatus according to an embodiment of the present invention will be described.

  As will be described later, this image forming apparatus is an apparatus that forms an image on a medium M (see FIG. 1) using toner, and is a so-called electrophotographic full-color printer. Although the kind of medium M is not specifically limited, For example, it is any 1 type or 2 types or more of paper, a film, etc.

  A series of rollers described below, that is, a series of components including the word “roller” in the name is a cylindrical member that extends in the Y-axis direction and extends in the Y-axis direction. It can be rotated around the rotation axis.

  Hereinafter, the front-rear relationship will be described in relation to the conveyance direction H (see FIG. 1) described later. Specifically, the downstream side in the transport direction H is the front, and the upstream side in the transport direction H is the rear.

<1-1. Overall configuration>
FIG. 1 schematically illustrates a planar configuration of the image forming apparatus. FIG. 2 shows a perspective configuration of the transfer unit 20 shown in FIG. 3 is an enlarged view of a part of the perspective configuration of the image forming apparatus shown in FIG. 1, and FIG. 4 is an enlarged schematic view of a part of the planar structure of the image forming apparatus shown in FIG. Represents. However, FIG. 4 also shows the medium M on which the toner is transferred by the transfer unit 20.

  For example, as shown in FIGS. 1 to 4, the image forming apparatus includes a tray T, a developing unit 10, a transfer unit 20, a support frame 30, a separation guide 40, A fixing unit 50, various rollers, and a switching guide 80 are provided. The various rollers include, for example, a pickup roller 61, a paper feed roller 62, a separation roller 63, a registration roller 64, a pressure roller 65, and conveying rollers 66 to 73. In the tray T, for example, a plurality of media M are stored in a stacked state. The housing 1 is provided with, for example, a stacker 2 for discharging the medium M on which an image is formed. Here, the separation guide 40 is a “separation member” according to an embodiment of the present invention, and the support frame 30 is a “support member” according to an embodiment of the present invention.

  The image forming apparatus described here can form an image on one side (front surface) of the medium M by switching the conveyance direction of the medium M using, for example, the switching guide 80, and both sides (front surface) of the medium M. And an image can be formed on the back surface.

  In this image forming apparatus, the medium M is transported in the transport direction H along each of the transport paths R1 to R4 indicated by broken lines. The transport path R <b> 1 is a path through which the medium M is transported from the tray T toward the developing unit 10 and the transfer unit 20. The conveyance path R <b> 2 is a path through which the medium M is conveyed from the developing unit 10 and the transfer unit 20 toward the fixing unit 50 when an image is formed on one side (front surface) of the medium M. The transport path R3 is a path through which the medium M is transported from the fixing unit 50 toward the stacker 2. The conveyance path R4 conveys the medium M again from the fixing unit 50 toward the developing unit 10 and the transfer unit 20 in order to form an image on the back surface of the medium M when images are formed on both sides of the medium M ( It is a route to be detoured.

[Development unit]
The development unit 10 performs development processing using toner. Specifically, the developing unit 10 forms, for example, an electrostatic latent image and attaches toner to the electrostatic latent image using Coulomb force.

  The development unit 10 includes, for example, a development processing unit 11 and an exposure processing unit 12. The development processing unit 11 performs development processing using toner. The development processing unit 11 includes, for example, a photosensitive drum 13 on which an electrostatic latent image is formed, and is detachable. The photosensitive drum 13 is a cylindrical member that extends in the Y-axis direction, and is rotatable around a rotation axis that extends in the Y-axis direction. The exposure processing unit 12 is attached to the development processing unit 11 and performs an exposure process to form an electrostatic latent image on the surface of the photosensitive drum 13. The exposure processing unit 12 includes, for example, a light emitting diode (LED) element and a lens array.

  Here, the developing unit 10 includes, for example, four developing units 11 (11K, 11Y, 11M, 11C) and four exposing units 12 (12K, 12Y, 12M, 12C). Each of the development processing units 11K, 11Y, 11M, and 11C is arranged in this order from the upstream side to the downstream side, for example, along the transport path R2. The arrangement order of the exposure processing units 12K, 12Y, 12M, and 12C is the same as the arrangement order of the development processing units 11K, 11Y, 11M, and 11C, for example.

  Each of the development processing units 11K, 11Y, 11M, and 11C has the same configuration except that, for example, the types (colors) of the toners used for the development processing are different from each other. Specifically, the development processing unit 11K is equipped with, for example, black toner. The development processing unit 11Y includes, for example, yellow toner. The development processing unit 11M includes, for example, magenta toner. The development processing unit 11C is equipped with cyan toner, for example.

[Transfer unit]
The transfer unit 20 performs a transfer process using the toner developed by the developing unit 10. Specifically, the transfer unit 20 transfers, for example, the toner attached to the electrostatic latent image by the developing unit 10 to the medium M transported in the transport direction H.

  The transfer unit 20 includes, for example, a drive roller 21, an idle roller 22, a transfer belt 23, and a transfer roller 24. Here, the drive roller 21 is a “rotating member” according to an embodiment of the present invention, and the transfer belt 23 is a “moving member” according to an embodiment of the present invention.

  For example, the drive roller 21 extends in a direction (Y-axis direction) that intersects the transport direction H, and can rotate around a shaft 21S that extends in the Y-axis direction. More specifically, the drive roller 21 can rotate around a turning axis J1 described later via a drive source such as a motor. The idle roller 22 can rotate according to the rotation of the drive roller 21, for example. The transfer belt 23 is, for example, an endless belt. The transfer belt 23 is, for example, a belt-like member stretched by a drive roller 21, an idle roller 22, and a transfer roller 24, and can move according to the rotation of the drive roller 21.

  The transfer roller 24 is pressed against the development processing unit 11 (photosensitive drum 13) via the transfer belt 23. Here, the transfer unit 20 includes, for example, four transfer rollers 24 (24K, 24Y, 24M, 24C) corresponding to the four development processing units 11 (11K, 11Y, 11M, 11C) described above. It is out. The arrangement order of the transfer rollers 24K, 24Y, 24M, and 24C is the same as the arrangement order of the development processing units 11K, 11Y, 11M, and 11C, for example.

  The transfer unit 20 is supported by a support frame 30. Thereby, for example, the transfer unit 20 can be pivoted with respect to the support frame 30 around the pivot axis J1 extending in the direction intersecting the transport direction H in a state where the transfer unit 20 is supported by the support frame 30. That is, in the transfer unit 20, the rear portion can move on a circular orbit centered on the pivot axis J 1 while the front portion is supported (fixed) by the support frame 30 at a position corresponding to the pivot axis J 1. The rotation axis J1 described here is not only used for rotating the transfer unit 20, but also used as a rotation axis for rotating the drive roller 21 as described above.

  Thereby, the transfer unit 20 can be attached to and detached from the support frame 30 by, for example, turning with respect to the support frame 30. That is, the transfer unit 20 can be attached to the support frame 30 using, for example, turning, and can be detached from the support frame 30 using turning. The reason why the transfer unit 20 is detached is not particularly limited. For example, the transfer unit 20 is repaired or replaced.

  A detailed configuration of the transfer unit 20 and a mechanism for attaching and detaching the transfer unit 20 using rotation will be described later (see FIGS. 5 to 11).

[Support frame]
The support frame 30 is separated from the developing unit 10 and supports, for example, the transfer unit 20 and the separation guide 40. More specifically, the support frame 30 supports, for example, the transfer unit 20 so as to be rotatable, and supports the separation guide 40 so as to be movable.

  The support frame 30 includes a pair of frame portions 31L and 31R to support the transfer unit 20 and the separation guide 40, for example. The frame portion 31L is, for example, a plate-like member extending in the Z-axis direction, and supports the transfer unit 20 (frame portion 25L described later) so as to be rotatable, and a separation guide 40 (holding plate 41 described later). ) Is movably supported. The frame portion 31R is, for example, a plate-like member extending in the Z-axis direction, and supports the transfer unit 20 (frame portion 25R described later) so as to be able to turn, and the separation guide 40 (holding plate 41). The other end is movably supported. That is, the frame portions 31L and 31R face each other with the transfer unit 20 in the Y-axis direction, for example.

  A detailed configuration of the support frame 30 will be described later (see FIGS. 5 to 11).

[Separation guide]
The separation guide 40 transfers the toner from the transfer unit 20 (transfer belt 23) to the fixing unit 50 after the toner is transferred to the medium M by the transfer unit 20 and then transferred from the transfer unit 20 to the fixing unit 50. Let M be separated. The separation guide 40 is disposed on the downstream side of the transfer unit 20 in the transport direction H, and is separated from the transfer unit 20.

  The separation guide 40 can move back and forth in the transport direction H in conjunction with the turning of the transfer unit 20 described above. That is, the separation guide 40 can move in a direction approaching the transfer unit 20 and can move in a direction retreating from the transfer unit 20.

  Specifically, the separation guide 40 includes, for example, a holding plate 41 and a guide film 42.

  The holding plate 41 holds the guide film 42. The holding plate 41 is a plate-like member extending in the Y-axis direction, and both end portions of the holding plate 41 are supported by the support frame 30, for example. Further, as described above, the holding plate 41 is movable back and forth in the transport direction H in conjunction with the turning of the transfer unit 20.

  The guide film 42 separates the medium M from the transfer unit 20. The guide film 42 is a film-like member extending in the Y-axis direction, and protrudes rearward (transfer unit 20) from the holding plate 41. However, the guide film 42 is separated from the transfer unit 20 as described above. The guide film 42 can move back and forth according to the movement of the holding plate 41 described above.

  Here, the details regarding the function of the guide film 42 are as described below. Hereinafter, the function of the guide film 42 described here is referred to as “medium M separation function”.

  When toner is transferred to the medium M by the transfer unit 20, the medium M is easily attracted to the surface of the transfer belt 23 due to static electricity or the like. In this case, if the medium M is not sufficiently separated from the transfer belt 23 when the medium M is transported from the transfer unit 20 to the fixing unit 50, the transfer belt 23 remains adsorbed while the medium M is adsorbed. Moving. As a result, the medium M unintentionally sticks to the transfer belt 23, so that not only the medium M is not supplied to the fixing unit 50 but also a so-called jam easily occurs. This jam is, for example, clogging of the medium M and winding of the medium M around the transfer belt 23.

  In this case, the guide film 42 separates the medium M from the transfer belt 23. Specifically, when the medium M is transported from the transfer unit 20 toward the fixing unit 50, the drive roller is transported to the vicinity of the drive roller 21 as shown in FIG. Due to the curvature of the transfer belt 23 in the vicinity of 21, a part of the medium M (tip portion MP) is peeled off from the transfer belt 23, so that the tip portion MP floats from the surface of the transfer belt 23. In particular, the tip portion MP becomes easier to peel from the transfer belt 23 as the strain (rigidity) of the medium M is higher, for example. When the medium M is transported from the transfer unit 20 to the fixing unit 50, the guide film 42 is fixed to the medium M while being peeled from the transfer belt 23 by being submerged below the leading end MP. Guide to unit 50. As a result, the medium M is less likely to stick to the transfer belt 23, and jamming is less likely to occur.

[Fixing unit]
The fixing unit 50 performs fixing processing using the toner transferred to the medium M by the transfer unit 20. Specifically, the fixing unit 50 fixes the toner to the medium M by, for example, applying pressure while heating the medium M on which the toner has been transferred by the transfer unit 20.

  The fixing unit 50 includes, for example, a heating roller 51 and a pressure roller 52. The heating roller 51 heats the toner transferred to the medium M. The pressure roller 52 is in pressure contact with the heating roller 51 and pressurizes the toner transferred to the medium M.

[Various rollers and switching guides]
The pickup roller 61 takes out the medium M from the tray T. The paper feed roller 62 guides the medium M taken out from the tray T by the pickup roller 61 from the transport path R1 to the transport path R2. The separation roller 63 separates another unnecessary medium M from the uppermost medium M when a plurality of mediums M are taken out from the tray T. The registration roller 64 and the pressure roller 65 correct the skew of the medium M. Each of the transport rollers 66 to 73 includes a pair of rollers facing each other via transport paths R2 to R4, and transports the medium M along the transport paths R2 to R4. Among these, the transport roller 68 functions as a discharge roller that discharges the medium M on which the image is formed to the stacker 2.

  The switching guide 80 switches the conveyance direction of the medium M according to the image formation format. For example, the switching guide 80 is disposed on the downstream side of the fixing unit 50 in the transport direction H. When an image is formed only on one side (front surface) of the medium M, the switching guide 80 transports the medium M in this order along, for example, the transport paths R2 and R3. When images are formed on both surfaces (front surface and back surface) of the medium M, the switching guide 80 transports the medium M along each of the transport paths R2 to R4, for example.

<1-2. Desorption mechanism of transfer unit>
Each of FIGS. 5 to 7 represents a perspective configuration of the image forming apparatus when the transfer unit 20 is mounted, and each of FIGS. 8 to 10 is a perspective configuration of the image forming apparatus when the transfer unit 20 is detached. Represents. FIG. 11 schematically shows an enlarged part of the planar configuration of the image forming apparatus shown in FIG. 8, and corresponds to FIG.

  5, 6, 8, and 9 show the left side portion in the vicinity of the transfer unit 20, and FIGS. 7 and 10 each show the right side portion in the vicinity of the transfer unit 20. ing. 5 and FIG. 8 show a state in which the vicinity of the transfer unit 20 is viewed from the outside, and in each of FIGS. 6, 7, 9 and 10, the vicinity of the transfer unit 20 is inward. The state seen from.

[Transfer unit]
The transfer unit 20 further includes a holding frame 25 as shown in FIGS. For example, the holding frame 25 includes a pair of frame portions 25L and 25R in order to rotatably hold the drive roller 21, the idle roller 22, and the transfer roller 24. The frame portion 25L is, for example, a plate-like member extending in the X-axis direction, and rotatably holds one end portion of each of the drive roller 21, the idle roller 22, and the transfer roller 24. The frame portion 25R is, for example, a plate-like member extending in the X-axis direction, and rotatably holds the other end portions of the drive roller 21, the idle roller 22, and the transfer roller 24. That is, for example, the frame portions 25L and 25R face the drive roller 21, the idle roller 22, the transfer belt 23, and the transfer roller 24 in the Y-axis direction.

  For example, as shown in FIGS. 3, 5, 6, 8, and 9, the frame portion 25L has a circular rotation assisting portion 25LS at a position corresponding to one end portion of the drive roller 21, For example, a tapered surface 25F is provided on the outer periphery of the rotation assisting portion 25LS. For example, when the transfer unit 20 is pivoted backward (first direction) about the pivot axis J1 when the transfer unit 20 is attached to the support frame 30, the frame portion 25L rotates the rotation assisting portion 25LS (the taper surface 25F Since the portion not provided) comes into contact with a rotation lever 32L (contact plate 32LY) described later, the contact plate 32LY is pushed forward. On the other hand, when the transfer unit 20 is detached from the support frame 30, for example, when the transfer unit 20 turns in the forward direction (the second direction) opposite to the rear with the turning axis J1 as a center, the frame portion 25L Since 25LS (the portion where the tapered surface 25F is provided) is brought into contact with the rotary lever 32L (the contact plate 32LY), the contact plate 32LY is pulled backward.

  For example, a bearing 25LP that rotatably holds one end portion of the shaft 21S is provided on the outer surface of the rotation assisting portion 25LS. The bearing 25LP is, for example, a cylindrical member that protrudes outward, and is fixed to the rotation assisting portion 25LS. Thereby, for example, since the bearing portion 25LP can rotate around the turning axis J1, the frame portion 25L can turn around the turning axis J1 according to the rotation of the bearing 25LP.

  The bearing 25LS is provided with, for example, a protrusion 25LM that rotates in response to the turning of the frame 25L. The protrusion 25LM can move on a circular orbit about the turning axis J1 according to the turning of the frame 25L.

  For example, as illustrated in FIGS. 3, 7, and 10, the frame portion 25 </ b> R has substantially the same configuration as the above-described frame portion 25 </ b> L.

  That is, the frame portion 25R has, for example, a circular rotation assisting portion 25RS at a location corresponding to the other end portion of the drive roller 21, and a taper surface 25F is provided on the outer periphery of the rotation assisting portion 25RS, for example. It has been. For example, when the transfer unit 20 turns rearward about the turning axis J1, the frame portion 25R is rotated by a rotation lever 32R (contact plate 32RY) described later by the rotation auxiliary portion 25RS (a portion where the taper surface 25F is not provided). The contact plate 32RY is pushed forward. On the other hand, in the frame portion 25R, for example, when the transfer unit 20 pivots forward about the pivot axis J1, the rotation assisting portion 25RS (the portion where the tapered surface 25F is provided) becomes the rotation lever 32R (contact plate 32RY). Since the contact is made, the contact plate 32RY is pulled backward.

  For example, a bearing 25RP that rotatably holds the other end portion of the shaft 21S is provided on the outer surface of the rotation assisting portion 25RS. The bearing 25RP is, for example, a cylindrical member that protrudes outward and is fixed to the rotation assisting portion 25RS. Thereby, for example, since the bearing portion 25RP can rotate around the turning axis J1, the frame portion 25R can turn around the turning axis J1 according to the rotation of the bearing 25RP.

[Support frame]
For example, as shown in FIGS. 5, 6, 8, and 9, the frame portion 31 </ b> L is provided with a recess 31 </ b> LU and an opening 31 </ b> LK, and an opening / closing lever 32 </ b> L and springs 33 </ b> LA and 33 </ b> LB are attached. ing. Here, the opening / closing lever 32L is a “rotating contact member” according to an embodiment of the present invention. The spring 33LA is a “first biasing member” according to an embodiment of the present invention, and the spring 33LB is a “second biasing member” according to an embodiment of the present invention.

  The recess 31LU is provided, for example, at a position corresponding to the bearing 25LP in the frame 31L. The frame 25L is supported by the frame 31L by fitting the bearing 25LP into the recess 31LU. That is, the rotational position of the drive roller 21 and the turning position of the transfer unit 20 (position of the turning axis J1) are determined by the recess 31LU. The frame portion 25L can turn around the turning axis J1 in a state where the bearing 25LP is fitted in the recess portion 31LU.

  For example, a recess 31LM is further provided inside the recess 31LU. When the transfer unit 20 is mounted on the support frame 30, the bearing 25LP is fitted into the depression 31LU, and the bearing 25LP is rotated so that the protrusion 25LM is fitted into the depression 31LM. It is fixed to the frame part 31L.

  For example, the opening 31LK is provided at a position corresponding to one end of the holding plate 41 in the frame 31L. By inserting one end of the holding plate 41 into the opening 31LK, the holding plate 41 is supported by the frame portion 31L. The holding plate 41 can move back and forth in a state where one end is inserted into the opening 31LK.

  The rotation lever 32L is a member used to move the separation guide 40 (holding plate 41) back and forth when the transfer unit 20 is attached and detached. For example, the rotation lever 32L is disposed in front of the transfer unit 20. For example, a protrusion 34LB provided on the inner surface of the frame portion 31L is inserted into the rotation lever 32L. For this reason, the rotation lever 32L is supported by the frame part 31L, for example. For example, the rotation lever 32L can rotate around the protrusion 34LB, that is, can rotate around the rotation axis J2 extending in the direction along the turning axis J1. The rotation lever 32L includes, for example, contact plates 32LX and 32LY. The contact plate 32LX is one end portion of the rotation lever 32L, and is in contact with one end portion of the holding plate 41 from the rear. The contact plate 32LY is the other end portion of the rotation lever 32L, and the frame is viewed from the front. It is in contact with the portion 25L (rotation assisting portion 25LS). In other words, the frame portion 25L is in contact with the contact plate 32LY from the rear, and the holding plate 41 is in contact with the contact plate 32LX from the front. Here, the contact plate 32LY is a “first contact portion” according to an embodiment of the present invention, and the contact plate 32LX is a “second contact portion” according to an embodiment of the present invention.

  The springs 33LA and 33LB are members that bias the contact plates 32LX and 32LY in a predetermined direction by rotating the rotary lever 32L. The spring 33LA is wound around, for example, a protrusion 34LA provided on the inner surface of the frame portion 31L, and is in contact with one end portion of the holding plate 41 from the front. Thereby, the spring 33LA urges the holding plate 41 backward using the restoring force at the time of contraction. That is, the spring 33LA biases the holding plate 41 against the contact plate 32LX so that the holding plate 41 pushes the contact plate 32LX backward. The spring 33LB is wound around, for example, the above-described protrusion 34LB and is attached to the rotation lever 32L. As a result, the spring 33LB uses the restoring force at the time of contraction so that the rotation lever 32L is attached so that the contact plate 32LX moves forward and the contact plate 32LY rotates rearward. It is fast. That is, the spring 33LB biases the holding plate 41 against the contact plate 32LX so that the holding plate 41 pushes the contact plate 32LX forward.

  However, the urging force (restoring force) of the spring 33LB is larger than the urging force (restoring force) of the spring 33LA, for example. As a result, the force for moving the holding plate 41 forward using the biasing force of the spring 33LB is larger than the force for moving the holding plate 41 rearward using the biasing force of the spring 33LA. It has become.

  For example, as illustrated in FIGS. 3, 7, and 10, the frame portion 25 </ b> R has substantially the same configuration as the frame portion 25 </ b> L described above.

  That is, for example, a recess 31RU and an opening 31RK are provided in the frame portion 31R, and an opening / closing lever 32R and springs 33RA, 33RB are attached. Here, the opening / closing lever 32R is a “rotating contact member” according to an embodiment of the present invention.

  The recess 31RU is provided, for example, at a location corresponding to the bearing 25RP in the frame 31R. The frame 25R is supported by the frame 31R by fitting the bearing 25RP into the recess 31RU. The frame portion 25R can turn around the turning axis J1 in a state where the bearing 25RP is fitted in the recess portion 31RU.

  The opening 31RK is provided, for example, at a location corresponding to the other end of the holding plate 41 in the frame 31R. By inserting the other end of the holding plate 41 into the opening 31RK, the holding plate 41 is supported by the frame portion 31R. The holding plate 41 can move back and forth in a state where one end is inserted into the opening 31RK.

  For example, since the protrusion 34RB provided on the inner surface of the frame portion 31R is inserted into the rotation lever 32R, the rotation lever 32R can rotate around the protrusion 34RB (rotation axis J2), for example. is there. That is, the rotation lever 32R is supported by the frame portion 31R, for example. The rotating lever 32R includes, for example, contact plates 32RX and 32RY. The contact plate 32RX is in contact with the other end of the holding plate 41 from the rear, and the contact plate 32RY is in contact with the frame portion 25R (rotation assisting portion 25RS) from the front. In other words, the frame portion 25R is in contact with the contact plate 32RY from the rear, and the holding plate 41 is in contact with the contact plate 32RX from the front. Here, the contact plate 32RY is a “first contact portion” according to an embodiment of the present invention, and the contact plate 32RX is a “second contact portion” according to an embodiment of the present invention.

  The springs 33RA and 33RB are members that urge the contact plates 32RX and 32RY in a predetermined direction by rotating the rotary lever 32R. The spring 33RA is wound around, for example, a protrusion 34RA provided on the inner surface of the frame portion 31R, and is in contact with the other end portion of the holding plate 41 from the front. Accordingly, the spring 33RA biases the holding plate 41 rearward. That is, the spring 33RA biases the holding plate 41 against the contact plate 32RX so that the holding plate 41 pushes the contact plate 32RX backward. The spring 33RB is wound around, for example, a protrusion 34RB provided on the inner surface of the frame portion 31R, and is attached to the rotation lever 32R. Accordingly, the spring 33RB biases the rotation lever 32R so that the contact plate 32RX is directed forward and the contact plate 32RY is rotated rearward. That is, the spring 33RB biases the holding plate 41 against the contact plate 32RX so that the holding plate 41 pushes the contact plate 32RX forward.

  However, the biasing force of the spring 33RB is larger than the biasing force of the spring 33RA, for example. As a result, the force for moving the holding plate 41 forward using the biasing force of the spring 33RB is larger than the force for moving the holding plate 41 backward using the biasing force of the spring 33RA. It has become.

<1-3. Operation>
Hereinafter, the image forming operation will be described, and then the transfer unit 20 attaching / detaching operation will be described.

[Image formation operation]
When forming an image on the medium M, the image forming apparatus performs, for example, development processing, transfer processing, and fixing processing in this order, as described below.

  First, after the medium M stored in the tray T is taken out by the pickup roller 61, the medium M is transported along the transport paths R1 and R2 in this order. Subsequently, in the development process, after an electrostatic latent image is formed on the surface of the photosensitive drum 13 in the developing unit 10, toner is attached to the electrostatic latent image. Subsequently, in the transfer process, the toner attached to the electrostatic latent image is transferred to the medium M by the transfer unit 20. Finally, in the fixing process, the toner transferred to the medium M is heated and pressed by the fixing unit 50 (the heating roller 51 and the pressure roller 52). As a result, the toner is fixed on the medium M, so that an image is formed on the medium M. The medium M on which the image is formed is discharged to the stacker 2. Note that the type (color and number) of toner used to form an image is determined according to the combination of colors necessary to form the image.

[Transfer unit removal / attachment]
FIG. 12 shows a perspective configuration of the image forming apparatus corresponding to FIG. 8 in order to explain the detaching operation of the transfer belt 23. Hereinafter, the state when the transfer unit 20 is mounted will be described with reference to FIGS. 2 to 7, and then the detaching operation of the transfer unit 20 will be described with reference to FIGS. 8 to 12.

(State when the transfer unit is installed)
In a state before the transfer unit 20 is detached from the support frame 30, that is, in a state where the transfer unit 20 is attached to the support frame 30, for example, as shown in FIGS. The transfer unit 20 is fixed (locked) to the support frame 30. More specifically, the transfer unit 20 is supported by the support frame 30 (frame portion 31L).

  In this case, in a state where the bearing 25LP provided in the frame portion 25L is fitted in the recess portion 31LU provided in the frame portion 31L, the bearing 25LP rotates backward about the turning axis J1. In this state, since the position of the frame portion 25L (bearing 25LP) is fixed using the depression 31LU, the position of the transfer unit 20 held by the frame portion 25L is also fixed.

  Thereby, since the frame portion 25L holding the transfer unit 20 is swiveled backward about the swivel axis J1, the transfer unit 20 is substantially horizontal. In addition, since the protrusion 25LM provided on the bearing 25LP is fitted in the recess 31LM provided on the frame 31L, the frame 25L (bearing 25LP) holding the transfer unit 20 becomes the frame 31L (depression). 31LM).

  In particular, in a state where the frame portion 25L is pivoted rearward about the pivot axis J1, as shown in FIG. 6, the rotation assisting portion 25LS (the portion where the tapered surface 25F is not provided) abuts against the abutting plate 32LY. Has been.

In this case, due to the frame portion 25L turning with a force stronger than the urging force of the spring 33LB (the force of the user turning the transfer unit 20 backward), the contact plate is rotated by the rotation assisting portion 25LS. 32LY is pushed forward, and the contact plate 32LX is retracted (separated) from the holding plate 41. That is, the rotation lever 32L rotates about the rotation axis J2 so that the contact plate 32LX is directed rearward and the contact plate 32LY is directed forward.
As a result, the urging force of the spring 33LB does not act on the holding plate 41, and the holding plate 41 is moved rearward using the urging force of the spring 33LA.

  Therefore, as shown in FIGS. 4 to 6, the holding plate 41 is moved rearward, that is, in a direction approaching the transfer unit 20, as the transfer unit 20 is swung rearward. The guide film 42 held by is approaching the transfer unit 20. The distance (gap) G (G1) between the transfer unit 20 and the guide film 42 is not particularly limited, and is, for example, 0.3 mm to 0.6 mm.

  In this case, since the one end of the holding plate 41 is inserted into the opening 31LK provided in the frame portion 31L, the holding plate 41 can move only inside the opening 31LK. The movement range of the holding plate 41 is regulated using the opening 31LK. Thereby, even if the holding plate 41 moves rearward, the moving range of the holding plate 41 is limited so that the holding plate 41 does not collide with the transfer unit 20, that is, the gap G1 is secured. Yes.

  The operation of the frame portion 25R (bearing 25RP), the frame portion 31R (the recess portion 31RU, the opening portion 31RK), the rotation lever 32R (the contact plates 32RX, 32RY) and the springs 33RA, 33RB when the transfer unit 20 is mounted. Are the same as the operations of the frame portion 25L (bearing 25LP), the frame portion 31L (the recess portion 31LU, the opening portion 31LK), the rotation lever 32L (the contact plates 32LX, 32LY), and the springs 33LA, 33LB ( (See FIG. 7).

(Transfer unit release operation)
When the transfer unit 20 is detached from the support frame 30, the frame 25L is turned forward by rotating the bearing 25LP forward in the state shown in FIGS. As a result, as shown in FIGS. 8 and 9, the protrusion 25LM is detached from the recess 31LM, so that the frame 25L is released (unlocked) from the frame 31L. Further, the transfer unit 20 is inclined so that the rear portion is higher than the front portion.

  In this case, the rotation assisting portion 25LS (the portion provided with the tapered surface 25F) is brought into contact with the contact plate 32LY in accordance with the turning of the frame portion 25L, and therefore, the contact plate 32LY is supported by the rotation assisting portion 25LS. Will not be pushed forward. As a result, the urging force of the spring 33LB becomes dominant over the urging force of the spring 33LA, so that the abutting plate 32LX is directed forward and the abutting plate 32LY is directed rearward using the urging force of the spring 33LB. The rotation lever 32L rotates around the rotation axis J2. That is, since the frame portion 25L moves backward from the contact plate 32LY, the contact plate 32LX pushes the holding plate 41 forward.

  Therefore, as shown in FIGS. 8, 9, and 11, since the holding plate 41 moves forward when the transfer unit 20 is turned forward, the guide film held by the holding plate 41. 42 moves backward from the transfer unit 20. That is, the guide film 42 moves away from the transfer unit 20. Thereby, the gap G2 between the transfer unit 20 and the guide film 42 is larger than the above-described gap G1. The value of the gap G2 is not particularly limited and can be set arbitrarily.

  In this case, not only the urging force of the spring 33LB acts on the holding plate 41 but also the urging force of the spring 33LA acts on the holding plate 41. The movement range is regulated. Thereby, even if the holding plate 41 moves forward, the moving range of the holding plate 41 is limited so that the holding plate 41 does not fall off from the frame portion 31L.

  The operation of the frame portion 25R (bearing 25RP), the frame portion 31R (the recess portion 31RU, the opening portion 31RK), the rotation lever 32R (the contact plates 32RX, 32RY) and the springs 33RA, 33RB when the transfer unit 20 is detached. Are the same as the operations of the frame portion 25L (bearing 25LP), the frame portion 31L (the recess portion 31LU, the opening portion 31LK), the rotation lever 32L (the contact plates 32LX, 32LY), and the springs 33LA, 33LB ( (See FIG. 10).

  As a result, as shown in FIG. 12, the transfer unit 20 is released from the support frame 30 (the frame portions 31 </ b> L and 31 </ b> R), so that the transfer unit 20 is detached from the support frame 30. Accordingly, the transfer operation of the transfer unit 20 is completed.

(Transfer unit mounting operation)
Although not described in detail here, the transfer unit 20 is fixed to the support frame 30 by performing an operation in the order opposite to the order of the detachment operation of the transfer unit 20 described above. Mounted on the frame 30.

<1-4. Action and Effect>
According to this image forming apparatus, the transfer unit 20 and the separation guide 40 are provided, and the separation guide 40 approaches or retracts from the transfer unit 20 in conjunction with the turning of the transfer unit 20.

  In this case, only by turning the transfer unit 20, the separation guide 40 automatically moves so as to approach the transfer unit 20, and the separation guide 40 automatically moves so as to retract from the transfer unit 20. To do. Accordingly, when the separation guide 40 is retreated from the transfer unit 20 when the transfer unit 20 is swung to be detached, the separation guide 42 is automatically moved away from the transfer unit 20. It becomes difficult to contact the separation guide 42.

  Therefore, the guide film 42 is less likely to be deformed and damaged, and the separation function of the medium M by the separation guide 40 is easily maintained. Further, since the transfer belt 23 is not easily damaged, medium contamination due to unintentional adhesion of toner to the transfer belt 23 is less likely to occur. This medium contamination is a phenomenon in which the toner re-adheres to the medium M due to the toner entering the inside of the scratch (groove-shaped defect) formed on the surface of the transfer belt 23. It tends to occur in the vicinity of the front end of M, the vicinity of the rear end, the back surface, and the like. However, medium contamination may occur due to the toner adhering to the guide film 42 unintentionally and then re-adhering to the medium M.

  For these reasons, since the separation function of the medium M by the separation guide 40 is maintained while suppressing the occurrence of medium contamination, an image can be stably formed on the medium M.

  In particular, if the transfer unit 20 can be attached to and detached from the support frame 30 by using rotation, the transfer unit 20 is moved backward from the transfer unit 20 when the transfer unit 20 is detached, as described above. When the transfer unit 20 is easily contacted with the separation guide 40, the separation guide 40 is less likely to stably contact the transfer unit 20. Therefore, medium contamination is less likely to occur, and the separation function of the medium M by the separation guide 40 is more easily maintained, so that a higher effect can be obtained.

  The separation guide 40 approaches the transfer unit 20 when the transfer unit 20 is turned in a predetermined direction (for example, rearward) when attached to the support frame 30, and the transfer unit 20 is separated when detached from the support frame 30. If the separation guide 40 moves backward from the transfer unit 20 when it is swung in the opposite direction (for example, forward), the positional relationship between the transfer unit 20 and the separation guide 40 is automatically set according to the turning direction of the transfer unit 20. Can be switched automatically. Therefore, when the transfer unit 20 is mounted, the guide film 42 automatically performs the function of separating the medium M, and when the transfer unit 20 is detached, the contact of the separation guide 40 with the transfer unit 20 is automatically prevented. Therefore, a higher effect can be obtained.

  Further, if the transfer unit 20 (bearing 25LP) has the protruding portion 25LM and the support frame 30 has the recessed portion 31LM, when the transfer unit 20 is mounted on the support frame 30, the recessed portion 31LM protrudes. The transfer unit 20 is fixed to the support frame 30 by fitting the portion 25LM. Thereby, when the transfer unit 20 is mounted, the position of the transfer unit 20 becomes difficult to shift. Therefore, since the gap G1 is less likely to fluctuate, a higher effect can be obtained.

  Further, if the support frame 30 not only supports the transfer unit 20 so as to be rotatable but also supports the separation guide 40 so as to be movable, each of the transfer unit 20 and the separation guide 40 is separately provided. The distance (gap G1) between the transfer belt 20 and the separation guide 40 is less likely to fluctuate compared to the case where it is supported by this member. Therefore, since the separation guide 40 is less likely to come into contact with the transfer belt 20, a higher effect can be obtained. In this case, the value of the gap G1 can be set to an extremely small value by utilizing the fact that the gap G1 is less likely to fluctuate.

  Further, if the transfer unit 20 includes a drive roller 21 and a transfer belt 23, a rotation shaft (rotation axis J 1) of the transfer unit 20 and rotation of the drive roller 21 used to move the transfer belt 23. The common shaft is shared with each other. As a result, the transfer unit 20 can rotate and the drive roller 21 can also rotate based on one axis (the rotation axis J1). Therefore, the transfer unit 20 can be stably rotated, and the drive roller 21 can also be stably rotated, so that a higher effect can be obtained.

  In addition, if the rotary lever 32L that can rotate about the rotation axis J2 and includes the contact plates 32LX and 32LY is provided, the rotation lever 32L rotates in response to the turning of the transfer unit 20, so that the contact is achieved. The holding plate 41 moves back and forth using the contact relationship with the plate 32LX. Therefore, since the guide film 42 is easily moved back and forth in conjunction with the turning of the transfer unit 20, the guide film 42 is likely to approach or retreat with respect to the transfer unit 20, so that a higher effect can be obtained. it can. The operations and effects described here are similarly obtained with respect to the rotating lever 32R including the contact plates 32RX and 32RY.

  In this case, a spring 33LA that biases the holding plate 41 against the contact plate 32LX and a spring 33LB that biases the contact plate 32LX against the holding plate 41 with a biasing force larger than that of the spring 33LA. If the guide film 42 is provided, the guide film 42 is automatically moved back and forth automatically according to the turning of the transfer unit 20 by utilizing the difference between the urging force of the spring 33LA and the urging force of the spring 33LB. Therefore, the guide film 42 is more likely to approach or retract with respect to the transfer unit 20, so that a higher effect can be obtained. The operations and effects described here are similarly obtained with respect to the springs 33RA and 33RB.

<2. Modification>
5 to 11, the projection 25LM for fixing is provided on the bearing 25LP and the recess 31LM for fitting is provided on the frame 31L. However, a projection corresponding to the projection 25LM is not provided on the projection 25RP. In addition, a recess corresponding to the recess 31LM was not provided in the frame 31R.

  However, a fixing protrusion may be provided on the bearing 25RP, and a fitting recess may be provided on the frame 31R. In this case, since the transfer unit 20 is fixed to both the frame portions 31L and 31R, the position of the transfer unit 20 is less likely to be shifted when mounted, so that a higher effect can be obtained.

  Although the present invention has been described with reference to one embodiment, the aspect of the present invention is not limited to the aspect described in the embodiment. Accordingly, various modifications can be made with respect to aspects of the present invention. Specifically, for example, the image forming apparatus according to the embodiment of the present invention is not limited to a printer, and may be other apparatuses such as a copying machine, a facsimile machine, and a multifunction machine.

  DESCRIPTION OF SYMBOLS 10 ... Developing unit, 20 ... Transfer unit, 21 ... Drive roller, 23 ... Transfer belt, 25LM ... Projection part, 30 ... Support frame, 31LM ... Recessed part, 32L, 32R ... Rotating lever, 32LX, 32LY, 32RX, 32RY ... Contact plate, 33LA, 33LB, 33RA, 33RB ... spring, 40 ... separation guide, 50 ... fixing unit, H ... conveying direction, J1 ... swivel axis, J2 ... rotation axis, M ... medium.

Claims (8)

A developing unit for attaching toner to the electrostatic latent image;
A support member spaced from the developing unit;
The toner attached to the electrostatic latent image is transferred to a medium supported by the support member and conveyed in the conveyance direction, and the rotation axis extending in a direction intersecting the conveyance direction is the center. A transfer unit that pivots relative to the support member;
Separation that is arranged downstream of the transfer unit in the transport direction and separates the medium onto which the toner has been transferred from the transfer unit, and approaches or retracts the transfer unit in conjunction with rotation of the transfer unit. An image forming apparatus comprising: a member; The transfer unit is detachable from the support member by turning with respect to the support member.
The image forming apparatus according to claim 1. The transfer unit turns in a first direction when the transfer unit is mounted on the support member, and turns in a second direction opposite to the first direction when the transfer unit is detached from the support member.
The separating member approaches the transfer unit when the transfer unit turns in the first direction, and retreats from the transfer unit when the transfer unit turns in the second direction.
The image forming apparatus according to claim 2. The transfer unit has a protrusion that rotates in response to the rotation of the transfer unit;
The support member has a recess portion into which the protrusion is fitted when the transfer unit is attached to the support member.
The image forming apparatus according to claim 2 or 3. The separation member is supported by the support member;
The image forming apparatus according to claim 1. The transfer unit is
A rotating member that extends in a direction intersecting the transport direction and rotates about the pivot axis;
The image forming apparatus according to claim 1, further comprising: a belt-shaped moving member that is stretched by the rotating member and moves according to the rotation of the rotating member. Further, the first abutment is supported by the support member and is rotatable about a rotation axis extending in a direction along the pivot axis, and the transfer unit is abutted from the upstream side in the transport direction. A rotation contact member including a second contact portion on which the separation member is contacted from a downstream side in the transport direction,
When the transfer unit turns in the first direction, the rotary contact member rotates so that the transfer unit pushes the first contact portion and the second contact portion moves backward from the separation member. As a result, the separating member approaches the transfer unit,
When the transfer unit turns in the second direction, the rotary contact member rotates so that the transfer unit moves backward from the first contact portion and the second contact portion presses the separation member. The separation member is retracted from the transfer unit,
The image forming apparatus according to claim 3. further,
A first urging member that urges the separation member against the second abutment portion so that the separation member presses the second abutment portion;
The second abutting portion is urged against the separating member so that the rotating abutting member rotates in a direction in which the second abutting portion pushes the separating member, and the first urging member is biased. The image forming apparatus according to claim 7, further comprising: a second urging member having an urging force larger than the urging force.

Images