WO2021053894A1 - Image forming device - Google Patents

Abstract

The purpose of the present invention is to save space. An image forming device according to the present invention comprises: an image forming unit that forms an image on a recording medium; a fixing unit that fixes the image to the recording medium by heating or drying the recording medium; and a conveyance unit that conveys the recording medium from the image forming unit to the fixing unit.

Description

Image forming device

The present invention relates to an image forming apparatus.

Patent Document 1 discloses a configuration in which a gripper provided on the peripheral surface of a transport drum grips the tip of the paper to transport the paper.

Japanese Patent Application Laid-Open No. 2012-96863

In a configuration in which an orbiting member to which a holding portion for holding a recording medium is attached is orbited to convey the recording medium, the image forming portion for forming an image on the recording medium and the fixing portion for fixing the image on the recording medium are respectively orbited. When arranging the members and passing the recording medium between the holding portions of the respective peripheral members, a large space is required.

An object of the present invention is to save space in an image forming apparatus.

The image forming apparatus according to the first aspect of the present invention has a first body supporting a recording medium and a first rotating body arranged at an axial end of the first body, and the recording medium has a first body of revolution. It has an image forming portion for forming an image, a second body supporting the recording medium, and a second rotating body arranged at the axial end of the second body, and heats or dries the recording medium. By doing so, the fixing portion for fixing the image on the recording medium, the first rotating body and the second rotating body are stretched, and the first rotating body and the second rotating body rotate with the rotation of the first rotating body and the second rotating body. A transport unit having an orbiting member and a holding portion attached to the orbiting member and holding the recording medium, and transporting the recording medium from the image forming portion to the fixing portion by orbiting the orbiting member. To be equipped.

The image forming apparatus according to the second aspect of the present invention is the image forming apparatus of the first aspect, and the orbiting member is wound around the first rotating body and the second rotating body.

The image forming apparatus according to the third aspect of the present invention is the image forming apparatus of the second aspect, and the maximum width of the transport portion in the width direction of the image forming apparatus is such that the circumferential member is the first rotating body. It is the length from the wound portion to the portion wound around the second rotating body.

The image forming apparatus according to the fourth aspect of the present invention is an image forming apparatus according to any one of the first to third aspects, and the image forming portion is an annular transfer belt on which an image is transferred to an outer surface. The first cylinder is a transfer cylinder having a transfer region for transferring the image from the transfer belt to the recording medium with the recording medium sandwiched between the outer surface of the transfer belt and the fixing portion. The pressurizing roll further has a heating portion and has a fixing region for fixing the image to the recording medium by sandwiching the recording medium with the outer surface of the heating portion. The medium is conveyed and passed through the transfer region and the fixation region.

The image forming apparatus according to the fifth aspect of the present invention is the image forming apparatus of the fourth aspect, which is provided between the image forming portion and the fixing portion in the transport direction of the recording medium, and is the recording medium. A non-contact heating unit that heats the image transferred to the image in a non-contact manner is further provided.

The image forming apparatus according to the sixth aspect of the present invention is the image forming apparatus of the fifth aspect, which faces the non-contact heating portion with the orbiting member interposed therebetween, and is conveyed by the conveying portion. A blower portion for blowing air to the back surface of the medium opposite to the surface on which the image is transferred is further provided.

The image forming apparatus according to the seventh aspect of the present invention is an image forming apparatus according to any one of the fourth to sixth aspects, and the outer diameter of the first rotating body is larger than the outer diameter of the transfer cylinder. Is also small.

The image forming apparatus according to the eighth aspect of the present invention is an image forming apparatus according to any one of the fourth to seventh aspects, and the transfer cylinder is wound around a base material and the outer periphery of the base material. It has a surface layer that can be exchanged with respect to the base material.

The image forming apparatus according to the ninth aspect of the present invention is an image forming apparatus according to any one of the fourth to eighth aspects, and the outer diameter of the second rotating body is the outer diameter of the pressure roll. Smaller than

The image forming apparatus according to the tenth aspect of the present invention is an image forming apparatus according to any one of the fourth to ninth aspects, and the pressure roll is wound around a base material and the outer periphery of the base material. It also has a surface layer that is interchangeable with respect to the substrate.

According to the first aspect of the present invention, it is possible to save space in the image forming apparatus.

According to the second aspect of the present invention, the orbiting member is bridged between the first rotating body and the second rotating body, and the other rotating bodies arranged on both sides of the first rotating body and the second rotating body, respectively. It is possible to save space in the image forming apparatus as compared with the configuration in which the image forming apparatus is wrapped around the body.

According to the third aspect of the present invention, the maximum width of the transport portion in the width direction of the image forming apparatus is such that the circumferential member is arranged on both sides of the first rotating body and the second rotating body, respectively. It is possible to save space in the image forming apparatus as compared with the configuration in which the length is up to the portion wrapped around the body.

According to the fourth aspect of the present invention, in the electrophotographic image forming apparatus using heat fixing, the heat of the fixing portion does not easily affect the transfer cylinder.

According to the fifth aspect of the present invention, the image on the back surface of the recording medium is suppressed from being disturbed as compared with the case where the heating means for heating the image transferred to the recording medium has a contact portion in contact with the back surface of the recording medium. Will be done.

According to the sixth aspect of the present invention, when the recording medium is conveyed while facing the front surface to the non-contact heating portion, the recording medium is in a windless state in which no wind is sent to the back surface of the recording medium. It is suppressed that the back surface in the image area comes into contact with the constituent members of the device.

According to the seventh aspect of the present invention, the recording medium is conveyed to the transfer cylinder and the transfer belt in the transfer region as compared with the configuration in which the outer diameter of the first rotating body is larger than the outer diameter of the transfer cylinder. The deviation to the downstream side in the direction is suppressed.

According to the eighth aspect of the present invention, when the surface layer deteriorates, it is not necessary to replace the transfer portion including the first rotating body.

According to the ninth aspect of the present invention, the recording medium is downstream in the transport direction with respect to the heating roll in the fixing region, as compared with the configuration in which the outer diameter of the second rotating body is larger than the outer diameter of the pressure roll. The shift to the side is suppressed.

According to the tenth aspect of the present invention, when the surface layer deteriorates, it is not necessary to replace the fixing portion including the second rotating body.

It is the schematic which shows the image forming apparatus which concerns on this embodiment. It is an enlarged perspective view which shows the secondary transfer part of the image forming apparatus which concerns on this embodiment. It is a side view which shows the secondary transfer part of the image forming apparatus which concerns on this embodiment in an enlarged manner. It is a side view which shows the sprocket provided in the transfer cylinder which concerns on this embodiment. It is a perspective view which shows the gripper which concerns on this embodiment. It is a side view which shows the sprocket provided in the pressure roll which concerns on this embodiment. It is a side view which shows the pressure roll which concerns on this embodiment. It is a perspective view which shows the gripper which concerns on the modification.

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

(Image forming apparatus 10)
The configuration of the image forming apparatus 10 according to the present embodiment will be described. FIG. 1 is a schematic view showing a configuration of an image forming apparatus 10 according to the present embodiment.

The image forming apparatus 10 shown in FIG. 1 is an example of an image forming apparatus that forms an image on a recording medium. Specifically, the image forming apparatus 10 is an electrophotographic image forming apparatus that forms a toner image (an example of an image) on a recording medium P. More specifically, the image forming apparatus 10 includes an image forming unit 14, a conveying unit 15, and a fixing device 16. Hereinafter, each part of the image forming apparatus 10 (that is, the image forming portion 14, the conveying portion 15, and the fixing device 16) will be described.

(Image forming unit 14)
The image forming unit 14 has a function of forming a toner image (an example of an image) on the recording medium P. Specifically, the image forming unit 14 includes a toner image forming unit 22 and a transfer device 17.

(Toner image forming unit 22)
A plurality of toner image forming portions 22 shown in FIG. 1 are provided so as to form a toner image for each color. In the present embodiment, a toner image forming unit 22 having a total of four colors of yellow (Y), magenta (M), cyan (C), and black (K) is provided. (Y), (M), (C), and (K) shown in FIG. 1 indicate components corresponding to the above colors.

In the image forming apparatus 10, when it is necessary to distinguish between yellow (Y), magenta (M), cyan (C), and black (K), (Y), (M), and (C) are added after the code of each member. ) And (K) are added, and (Y), (M), (C), and (K) may be omitted when it is not necessary to distinguish each color. Since the toner image forming unit 22 of each color is configured in the same manner except for the toner to be used, each part of the toner image forming unit 22 (Y) is designated with reference numerals on behalf of the toner image forming unit 22 of each color. doing.

Specifically, the toner image forming unit 22 of each color has a photoconductor drum 32 which is a photoconductor that rotates in one direction (for example, the counterclockwise direction in FIG. 1). Further, the toner image forming unit 22 of each color includes a charger 23, an exposure device 36, a developing device 38, and a removing device 40.

In the toner image forming unit 22 of each color, the charger 23 charges the photoconductor drum 32. Further, the exposure device 36 exposes the photoconductor drum 32 charged by the charger 23 to form an electrostatic latent image on the photoconductor drum 32. The developing device 38 develops the electrostatic latent image formed on the photoconductor drum 32 by the exposure device 36 to form a toner image. The removing device 40 removes the toner remaining on the photoconductor drum 32 after the toner image is transferred to the transfer belt 24 described later.

(Transfer device 17)
As shown in FIG. 1, the transfer device 17 includes a transfer belt 24, a primary transfer roll 26, a secondary transfer body 27, and a charger 60. The transfer device 17 shown in FIG. 1 is a device that transfers the toner image formed by the toner image forming unit 22 to the recording medium P. Specifically, the transfer device 17 superimposes the toner image of the photoconductor drum 32 of each color on the transfer belt 24 as an intermediate transfer body for primary transfer, and transfers the superimposed toner image to the secondary transfer position T2 (that is, that is). , Secondary transfer to the recording medium P in the nip region 28A) described later.

(Primary transfer roll 26)
The primary transfer roll 26 shown in FIG. 1 is a roll that transfers the toner image of the photoconductor drum 32 of each color to the transfer belt 24 at the primary transfer position T1 between the photoconductor drum 32 and the primary transfer roll 26. .. In the present embodiment, the toner image formed on the photoconductor drum 32 is transferred to the transfer belt 24 at the primary transfer position T1 by applying the primary transfer electric field between the primary transfer roll 26 and the photoconductor drum 32. Transcribed.

(Transfer belt 24)
The transfer belt 24 shown in FIG. 1 is an example of an annular transfer belt on which an image is transferred to an outer surface. Specifically, in the transfer belt 24, the toner image is transferred from the photoconductor drum 32 of each color to the outer peripheral surface (an example of the outer surface). More specifically, the transfer belt 24 is configured as follows. The transfer belt 24 is annular, as shown in FIG. Further, the transfer belt 24 is wound around a plurality of rolls 42 including the drive roll 42D, the winding rolls 42E, and 42F, and the posture is determined. The transfer belt 24, for example, is rotated in the predetermined arrow A direction (hereinafter referred to as belt circumferential direction A) by rotationally driving the drive roll 42D among the plurality of rolls 42 by a drive unit (not shown). To do. The specific configurations of the winding rolls 42E and 42F will be described later.

(Secondary transcript 27)
The secondary transfer member 27 is an example of a transfer unit. Specifically, as shown in FIG. 2, the secondary transfer body 27 has a transfer body 28 as an example of the first body and a pair of sprockets 29. The transfer cylinder 28 is an example of a transfer cylinder having a transfer region for transferring an image from the transfer belt to the recording medium by sandwiching the recording medium with the outer surface of the transfer belt. Specifically, as shown in FIG. 3, the transfer cylinder 28 has a nip region 28A (an example of a transfer region) that sandwiches the recording medium P with the outer peripheral surface of the transfer belt 24. Since the nip region 28A is a region in which the recording medium P is sandwiched, it can be said to be a sandwiched region. Since the transfer cylinder 28 sandwiches the recording medium P with the transfer belt 24, it can be said to be a sandwiched portion. In FIG. 3, the recording medium P is simplified and a part thereof is shown.

The nip region 28A is formed by winding the transfer belt 24 around the transfer cylinder 28. In other words, the nip region 28A can be said to be a contact region where the transfer belt 24 and the transfer cylinder 28 come into contact with each other. The nip region 28A is the secondary transfer position T2 at which the toner image is transferred from the transfer belt 24 to the recording medium P. The transfer cylinder 28 is conveyed by sandwiching the recording medium P with the transfer belt 24 in the nip region 28A.

The pair of sprockets 29 is an example of the first rotating body. The pair of sprockets 29 are arranged at the axial end of the transfer cylinder 28, as shown in FIG. Specifically, the pair of sprockets 29 are arranged on both ends in the axial direction of the transfer cylinder 28. In other words, the transfer cylinder 28 is provided between the pair of sprockets 29. The pair of sprockets 29 are arranged coaxially with the transfer cylinder 28 and rotate integrally with the transfer cylinder 28. The secondary transfer body 27 is rotationally driven by a drive unit (not shown). In the present embodiment, the axial direction of the transfer cylinder 28 is the same as the device front-rear direction (D direction in FIG. 2).

As shown in FIG. 4, the outer diameter R1 of the pair of sprockets 29 is smaller than the outer diameter of the transfer cylinder 28. The outer diameter R1 of the sprocket 29 referred to here is the outer diameter including the teeth 29A (that is, the diameter of the tooth tip). The outer diameter R1 of the sprocket 29 is preferably in the range of 50% to 95%, more preferably in the range of 70% to 90% with respect to the outer diameter of the transfer cylinder 28. In other words, it is preferable to set the outer diameter R1 of the sprocket 29 so that the chain 52 does not protrude from the outer periphery of the transfer cylinder 28 at the portion wound around the sprocket 29 of the chain 52.

The transfer cylinder 28 has a base material 28E and a surface layer 28F that is wound around the outer circumference of the base material 28E and can be exchanged with respect to the base material 28E. As the base material 28E, a metal material such as stainless steel is used. As the surface layer 28F, resin materials such as urethane rubber, ethylene / propylene rubber (EPM), silicone rubber, fluororubber (FKM), and epichlorohydrin / butadiene rubber are used. The surface layer 28F is removably fixed to the base material 28E. Therefore, it is possible to remove the surface layer 28F with respect to the base material 28E and attach an unused surface layer 28F.

Further, on the outer circumference of the transfer cylinder 28, two recesses 28D in which the gripper 54 and the mounting member 55 described later of the transport portion 15 are housed are formed. The number of recesses 28D may be one or three or more.

(Charger 60)
The charger 60 is an example of an opposing portion that faces the sandwiching portion inside the transfer belt. As shown in FIG. 3, the charger 60 is arranged inside the transfer belt 24 so as to face the transfer cylinder 28. Specifically, the charger 60 faces the transfer cylinder 28 in a region including the center 28S of the transport portion 15 in the transport direction in the nip region 28A.

The charger 60 is a charger (so-called corotron type charger) that transfers a toner image by corona discharge to transfer the toner image of the belt 24. Specifically, the charger 60 has a discharge wire 60A and a case 62 which is a housing. The discharge wire 60A is a linear wire having a length extending along the axial direction of the transfer cylinder 28. The discharge wire 60A is non-contact with the inner surface of the transfer belt 24. That is, there is a gap between the discharge wire 60A and the inner surface of the transfer belt 24.

Case 62 is an example of a surrounding portion surrounding the discharge wire. The case 62 is formed in a box shape and has an opening 62C on the transfer cylinder 28 side (that is, the lower side).

Specifically, the case 62 includes a first wall 62A arranged on the side opposite to the transfer cylinder 28 with respect to the discharge wire 60A, and a pair of cases arranged on the upstream side and the downstream side of the belt circumferential direction A with respect to the discharge wire 60A. It has a second wall 62B and. Further, the case 62 has third walls (not shown) arranged on both ends in the length direction of the discharge wire 60A.

This case 62 is non-contact with the inner surface of the transfer belt 24. That is, there is a gap between the case 62 and the inner surface of the transfer belt 24.

The case 62 may have openings in the third walls (not shown) arranged on both ends in the length direction of the discharge wire 60A, and the openings 62C may be provided at least on the transfer cylinder 28 side (that is, the lower side). Any configuration may be used.

In the charger 60, the recording medium P is electrostatically adsorbed on the transfer belt 24 and the transfer cylinder 28 by applying a voltage to the discharge wire 60A to discharge the battery. In the charger 60, the transfer belt 24 is charged by the discharge of the discharge wire 60A, and the toner image superimposed on the transfer belt 24 is transferred from the transfer belt 24 to the recording medium P in the nip region 28A which is the secondary transfer position T2. Transcribe.

(Rolling rolls 42E, 42F)
The winding rolls 42E and 42F shown in FIGS. 1 and 3 are examples of a pair of winding rolls in which the transfer belt is wound inside the transfer belt. The winding rolls 42E and 42F are arranged on the upstream side and the downstream side of the belt circumferential direction A with respect to the charger 60.

As shown in FIG. 3, the winding rolls 42E and 42F are arranged so that the common circumscribed line XA of the winding rolls 42E and 42F passes over the transfer cylinder 28 in the axial view of the winding rolls 42E and 42F. Has been done.

Here, the common circumscribed line XA is a tangent line in which the winding rolls 42E and 42F are arranged on the same side of the tangent line among the tangent lines tangent to both the winding rolls 42E and 42F (that is, the common tangent line). More specifically, the common circumscribed line XA according to the present embodiment is a tangent line in which the transfer belt 24 of the winding rolls 42E and 42F is in contact with the wound portion. In other words, the common circumscribed line XA according to the present embodiment is a tangent line that is in contact with the winding rolls 42E and 42F on the transfer cylinder 28 side with respect to the charger 60.

Both the winding portions 43E and 43F wound around the winding rolls 42E and 42F of the transfer belt 24 are separated from the transfer cylinder 28. The winding portion 43E is a winding portion on the upstream side in the transport direction of the recording medium P with respect to the winding portion 43F.

(Fixing device 16)
The fixing device 16 shown in FIG. 1 is a device that fixes the toner image transferred to the recording medium P by the transfer cylinder 28 to the recording medium P. Specifically, as shown in FIG. 1, the fixing device 16 has a heating roll 68 as a heating member, a pressure roll 69 as a pressure member, and a pair of sprockets 19. In FIG. 1, the sprocket 19 is omitted. In the fixing device 16, the toner image formed on the recording medium P is fixed on the recording medium P by heating and pressurizing the recording medium P with the heating roll 68 and the pressure roll 69. The fixing device 16 is an example of a fixing portion. The pressure roll 69 is an example of the second body.

The pair of sprockets 19 is an example of the second rotating body. The pair of sprockets 19 are arranged at the axial ends of the pressure roll 69. Specifically, the pair of sprockets 19 are arranged on both ends in the axial direction of the pressure roll 69. In other words, a pressure roll 69 is provided between the pair of sprockets 19. Further, the pair of sprockets 19 are arranged coaxially with the pressure roll 69 and rotate integrally with the pressure roll 69.

As shown in FIG. 6, the outer diameter R2 of the pair of sprockets 19 is smaller than the outer diameter of the pressure roll 69. The outer diameter R2 of the sprocket 19 referred to here is the outer diameter including the teeth 19A (that is, the diameter of the tooth tip). The outer diameter R2 of the sprocket 19 is preferably in the range of 50% to 95%, more preferably in the range of 70% to 90% with respect to the outer diameter of the pressure roll 69. In other words, it is preferable to set the outer diameter R2 of the sprocket 19 so that the chain 52 does not protrude from the outer circumference of the pressure roll 69 at the portion wound around the sprocket 19 of the chain 52.

On the outer circumference of the pressure roll 69, one recess 69D in which the gripper 54 and the mounting member 55 described later of the transport portion 15 are housed is formed. A plurality of recesses 69D may be formed according to the arrangement interval of the grippers 54 along the circumferential direction C of the chain 52.

The pressure roll 69 has a base material 69E and a surface layer 69F that is wound around the outer circumference of the base material 69E and can be exchanged with respect to the base material 69E. As the base material 69E, a metal material such as stainless steel is used. As the surface layer 69F, an elastic material such as silicone rubber or a release layer made of PFA or the like is sequentially laminated on an elastic material such as silicone rubber. The surface layer 69F is removably fixed to the base material 69E. Therefore, it is possible to remove the surface layer 69F with respect to the base material 69E and attach an unused surface layer 69F.

(Transport section 15)
The transport unit 15 shown in FIGS. 1 to 3 and the like has a function of transporting the recording medium P from the image forming unit 14 to the fixing device 16. Specifically, the transport unit 15 has a function of transporting the recording medium P and passing it through the nip region 28A of the image forming unit 14 and the nip region 69A of the fixing device 16 shown in FIG. More specifically, as shown in FIGS. 1 and 2, the transport unit 15 includes a pair of sprockets 19, a pair of sprockets 29, a pair of sprockets 46, a pair of sprockets 47, a pair of sprockets 48, and a pair. The chain 52, the gripper 54, and the suction roll 59 are provided. The pair of chains 52 is an example of a circumferential member. The gripper 54 is an example of a holding unit that holds a recording medium. In FIG. 1, the sprocket 46, the sprocket 47, the sprocket 48, the chain 52, and the gripper 54 are shown in a simplified manner, and the sprocket 19 and the sprocket 29 are omitted. In FIG. 3, the chain 52 and the gripper 54 are shown in a simplified manner.

As shown in FIG. 1, the pair of sprockets 46 are arranged on the lower side of the pair of sprockets 19 at intervals in the front-rear direction of the device. The pair of sprockets 46 are coaxially and integrally rotatable and supported by a device body (not shown) of the image forming apparatus 10.

As shown in FIG. 1, the pair of sprockets 47 are arranged on the lower side of the pair of sprockets 29 at intervals in the front-rear direction of the device. The pair of sprockets 47 are coaxially and integrally rotatable and supported by a device body (not shown) of the image forming apparatus 10.

As shown in FIG. 1, the pair of sprockets 48 are arranged between the pair of sprockets 46 and the pair of sprockets 47 in the device width direction (left-right direction in FIG. 1) and at intervals in the device front-rear direction. There is. The pair of sprockets 48 are coaxially and integrally rotatable and supported by a device body (not shown) of the image forming apparatus 10.

These sprockets 46, 47, 48 have a function of properly maintaining the tension of the chain 52.

The pair of chains 52 are formed in an annular shape as shown in FIG. As shown in FIG. 2, the pair of chains 52 are arranged at intervals in the front-rear direction of the device (D direction in FIG. 2). The pair of chains 52 are stretched on a pair of sprockets 19 provided on the pressure roll 69 and a pair of sprockets 29 provided on the transfer cylinder 28, respectively. Specifically, the pair of chains 52 are wound around the pair of sprockets 19, 29, 46, 47, 48, respectively. The rotation of the transfer cylinder 28 having the pair of sprockets 29 causes the chain 52 to orbit in the circumferential direction C (direction of arrow C in FIG. 1). Here, the chain 52 is wound so as to straddle at least a region of the nip region 28A facing the charger 60 in the circumferential direction C. As a result, since the recording medium P is conveyed by the chain 52 during the secondary transfer, the speed fluctuation of the recording medium P is suppressed at the secondary transfer position T2. Further, the chain 52 is wound so as to straddle the entire nip region 28A. As a result, the speed fluctuation of the recording medium P is more reliably suppressed at the secondary transfer position T2. In the present embodiment, the winding angle at which the chain 52 is wound around the sprocket 29 is 90 degrees or more. Therefore, the recording medium P is easily conveyed following the surface of the transfer cylinder 28.

In the present embodiment, the pair of sprockets 19, 46, 47, 48 are driven to rotate with respect to the rotation of the chain 52.

As shown in FIG. 1, the width from the portion where the chain 52 is wound around the sprocket 29 to the portion where the chain 52 is wound around the sprocket 19 when viewed from the front-rear direction of the device is the maximum width of the transport portion 15 in the device width direction. There is a maximum width portion of 52W. In other words, the sprockets 46, 47, 48 of the transport unit 15 are arranged in the region along the device width direction from the sprocket 19 to the sprocket 29.

As shown in FIG. 2, a mounting member 55 to which the gripper 54 is mounted is hung on the pair of chains 52 along the front-rear direction of the device. A plurality of mounting members 55 are fixed to a pair of chains 52 at predetermined intervals along the circumferential direction (circumferential direction C) of the chain 52.

As shown in FIG. 2, a plurality of grippers 54 are attached to the attachment member 55 at predetermined intervals along the front-rear direction of the device. In other words, the gripper 54 is attached to the chain 52 via the attachment member 55. The gripper 54 has a function of holding the front end portion of the recording medium P. Specifically, the gripper 54 has a claw 54A and a claw base 54B as shown in FIG. The gripper 54 holds the recording medium P by sandwiching the front end portion of the recording medium P between the claw 54A and the claw base 54B. In other words, the gripper 54 is an example of a holding portion that holds the recording medium P in the thickness direction.

More specifically, the gripper 54 holds the front end portion of the recording medium P outside the image area of the recording medium P. The image area of the recording medium P is an area in which the toner image is transferred in the recording medium P. In the gripper 54, for example, the claw 54A is pressed against the claw base 54B by a spring or the like, and the claw 54A is opened and closed against the claw base 54B by the action of a cam or the like.

In the transport unit 15, the front end portion of the recording medium P sent from the storage unit (not shown) in which the recording medium P is housed is held by the gripper 54 as shown in FIG. Further, in the transport unit 15, the chain 52 orbits in the circumferential direction C while the gripper 54 holds the front end portion of the recording medium P, thereby moving the gripper 54 to transport the recording medium P and recording with the gripper 54. While holding the medium P, it is passed through the nip region 28A together with the gripper 54. Further, in the transport unit 15, after passing the recording medium P through the nip region 28A, the recording medium P is conveyed to the fixing device 16 while being held by the gripper 54, and the nip region 69A (an example of the fixing region) is conveyed together with the gripper 54. ) Pass.

The suction roll 59 is in contact with the transfer cylinder 28 on the upstream side in the transport direction with respect to the nip region 28A. The suction roll 59 presses the recording medium P against the transfer cylinder 28 and charges the recording medium P by supplying power from the power source 57. As a result, the recording medium P is electrostatically attracted to the outer peripheral surface of the transfer cylinder 28.

In the circumferential direction C of the chain 52, no sprocket is provided between the time of passing through the nip area 28A and the time of reaching the nip area 69A.

According to this configuration, in the circumferential direction C of the chain 52, compared to a configuration in which a sprocket is provided between passing through the nip region 28A and reaching the nip region 69A, from after the secondary transfer to fixing. The chain 52 between them is wound so as to be linear, and the recording medium P on which the image is transferred is suppressed from being bent and conveyed.

As shown in FIG. 1, the image forming apparatus 10 heats the recording medium P in a non-contact state with the recording medium P between the secondary transfer body 27 and the fixing device 16 in the transport direction of the recording medium P. It has a non-contact heating unit 70. Here, the non-contact heating unit 70 includes a reflector 72 and a plurality of infrared heaters 74 (hereinafter, referred to as “heaters 74”).

-Reflector 72-
The reflector 72 is formed by using an aluminum plate, and has a shallow box shape in which the recording medium P side (lower side in FIG. 19) to be conveyed is open. In the present embodiment, the reflector 72 covers the conveyed recording medium P in the device depth direction (the depth direction of the paper surface in FIG. 1) when viewed from above.

-Heater 74-
A plurality of heaters 74 are infrared heaters having a columnar outer shape, are housed inside the reflector 72, and are arranged so as to extend in the depth direction of the device. In the present embodiment, the heater 74 covers the recorded recording medium P to be conveyed in the depth direction of the device when viewed from above. The plurality of heaters 74 are arranged in the device width direction. The heater 74 is an example of a non-contact heating unit.

Further, as shown in FIG. 1, the image forming apparatus 10 is viewed from the side of the chain 52 (specifically, in the circumferential direction C of the chain 52, the downstream side of the sprocket 29 and the upstream side of the sprocket 19). The blower unit 76 may be provided at a position facing the heater 74 with the portion) in between. The blower unit 76 includes a ventilation hole 80 facing the back surface of the recording medium P and a fan 78. The blower unit 76 is an example of a blower unit.

(Action according to this embodiment)
Next, the operation according to this embodiment will be described.

According to the image forming apparatus according to the present embodiment, the front end portion of the recording medium P sent from the accommodating portion (not shown) in which the recording medium P is accommodated is held by the gripper 54 as shown in FIG. .. Further, as shown in FIG. 3, the chain 52 orbits in the circumferential direction C with the gripper 54 holding the front end portion of the recording medium P, thereby moving the gripper 54 to convey the recording medium P and carrying the gripper. While holding the recording medium P at 54, the nip region 28A is passed together with the gripper 54. The recording medium P is electrostatically attracted to the transfer cylinder 28 by the suction roll 59 on the upstream side in the transport direction with respect to the nip region 28A.

When the recording medium P passes through the nip region 28A, the recording medium P is electrostatically attracted to the transfer belt 24 and the transfer cylinder 28 by the discharge of the discharge wire 60A in the charger 60. Due to the discharge of the discharge wire 60A in the charger 60, the toner image superimposed on the transfer belt 24 is transferred from the transfer belt 24 to the recording medium P in the nip region 28A which is the secondary transfer position T2.

The recording medium P that has passed through the nip area 28A is conveyed to the fixing device 16 while being held by the gripper 54, and passes through the nip area 69A together with the gripper 54. By passing through the nip region 69A, the toner image is fixed on the recording medium P.

In the present embodiment, since the chain 52 is stretched between the pair of sprockets 29 of the image forming portion 14 and the pair of sprockets 19 of the fixing device 16, the recording medium held by the gripper 54 attached to the chain 52. P is conveyed from the image forming unit 14 to the fixing device 16 by the circulation of the chain 52. Therefore, it is possible to save space as compared with the configuration in which the image forming unit 14 and the fixing device 16 use separate chains.

In this embodiment, the chain 52 is wound around the sprocket 29 and the sprocket 19. For this reason, it is possible to save space as compared with a configuration in which the chain 52 is bridged between the sprocket 29 and the sprocket 19 and is wound around other sprockets arranged on both sides of the sprocket 29 and the sprocket 19 in between. It will be possible.

In the present embodiment, the maximum width portion 52W is from the portion where the chain 52 is wound around the sprocket 29 to the portion where the chain 52 is wound around the sprocket 19. For this reason, it is possible to save space as compared with a configuration in which the maximum width portion 52W of the chain 52 corresponds to a portion wound around other sprockets arranged on both sides of the sprocket 29 and the sprocket 19 in between. It will be possible.

In the present embodiment, in the electrophotographic image forming apparatus 10 using heat fixing, the gripper 54 conveys the recording medium P by orbiting the chain 52 and passes through the nip region 28A and the nip region 69A. Therefore, by connecting a plurality of impression cylinders and passing the recording medium P to the grippers of each impression cylinder, the recording medium P is conveyed from the image forming unit 14 to the fixing device 16 and passes through the nip area 28A and the nip area 69A. Since the heat of the heating roll 68 of the fixing device 16 is not transferred to the transfer cylinder 28 through the plurality of impression cylinders, the heat is less likely to affect the transfer cylinder 28.

In the present embodiment, the outer diameter R1 of the pair of sprockets 29 is smaller than the outer diameter of the transfer cylinder 28, as shown in FIG. When the outer diameter R1 of the pair of sprockets 29 is larger than the outer diameter of the transfer cylinder 28, the peripheral speed of the sprockets 29 becomes larger than the peripheral speed of the transfer cylinder 28. As a result, the transport speed of the recording medium P held by the gripper 54 attached to the chain 52 wound around the sprocket 29 may be higher than the peripheral speed of the transfer cylinder 28. As a result, in the nip region 28A, the recording medium P may be pulled and displaced toward the downstream side in the transport direction with respect to the transfer cylinder 28 and the transfer belt 24.

On the other hand, in the present embodiment, as described above, the outer diameter of the pair of sprockets 29 is smaller than the outer diameter of the transfer cylinder 28, so that the outer diameter of the pair of sprockets 29 is equal to or larger than the outer diameter of the transfer cylinder 28. In the nip region 28A, the recording medium P is prevented from being displaced toward the downstream side in the transport direction with respect to the transfer cylinder 28 and the transfer belt 24, as compared with the configuration having the size of.

In the present embodiment, the transfer cylinder 28 has a base material 28E and a surface layer 28F that is wound around the outer circumference of the base material 28E and can be exchanged with respect to the base material 28E.

Therefore, when the surface layer 28F deteriorates, only the surface layer 28F needs to be replaced, and the secondary transfer member 27 including the pair of sprockets 29 does not need to be replaced.

In the present embodiment, the outer diameter R2 of the pair of sprockets 19 is smaller than the outer diameter of the pressure roll 69, as shown in FIG. When the outer diameter R2 of the pair of sprockets 19 is larger than the outer diameter of the pressure roll 69, the peripheral speed of the sprocket 19 becomes larger than the peripheral speed of the pressure roll 69. As a result, the transport speed of the recording medium P held by the gripper 54 attached to the chain 52 wound around the sprocket 19 may be higher than the peripheral speed of the pressure roll 69. As a result, in the nip region 69A, the recording medium P may be pulled and displaced toward the downstream side in the transport direction with respect to the heating roll 68.

On the other hand, in the present embodiment, since the outer diameter R2 of the pair of sprockets 19 is smaller than the outer diameter of the pressure roll 69, the outer diameter R2 of the pair of sprockets 19 is equal to or larger than the outer diameter of the pressure roll 69. In the nip region 69A, the recording medium P is prevented from being displaced downstream in the transport direction with respect to the heating roll 68, as compared with the configuration having a large diameter.

In the present embodiment, the pressure roll 69 has a base material 69E and a surface layer 69F that is wound around the outer circumference of the base material 69E and can be exchanged with respect to the base material 69E.

Therefore, when the surface layer 69F deteriorates, only the surface layer 69F needs to be replaced, and the fixing device 16 including the pair of sprockets 19 does not need to be replaced.

In the present embodiment, the non-contact heating unit 70 that heats the recording medium P in a non-contact state with the recording medium P is provided.

Therefore, in the transport direction of the recording medium P, there is a case where the secondary transfer body 27 and the fixing device 16 do not have a non-contact heating unit 70 that heats the recording medium P in a non-contact state with the recording medium P. In comparison, the image can be heated without contacting the recording medium P. By transporting the recording medium P from the nip area 28A to the nip area 69A while holding the recording medium P by the gripper 54, the recording medium is transported from the nip area 28A to the nip area 69A while the recording medium P is not held. The misregistration of P is suppressed.

Here, when double-sided printing is performed, an image may already be formed on the side of the recording medium P opposite to the side on which the image is transferred (hereinafter referred to as "back side"). When the recording medium P is heated in a non-contact manner, the transport portion that is in contact with the back surface of the recording medium P and is transported is heated by the heat received from the heater 74, and the image on the back surface of the recording medium P that is in contact with the transport member is distorted. There is. However, in the present embodiment, since the back surface of the recording medium P is conveyed so as not to contact in the region facing the heater 74, the image on the back surface of the recording medium P is suppressed from being disturbed.

In the present embodiment, the blower unit 76 is provided at a position facing the heater 74 with the chain 52 sandwiched in the side view.

Therefore, the fan 78 blows air toward the back surface of the recording medium P so that the sheet surface of the recording medium P conveyed between the blower unit 76 and the heater 74 faces in the vertical direction. The posture is stable. That is, by controlling the force of the air blown out from the fan 78, the rear end of the conveyed recording medium P is suppressed from moving downward with respect to the front end of the recording medium P. The ventilation holes 80 do not face the surface of the recording medium P on which the image is transferred. Therefore, it is suppressed that the image transferred to the recording medium P is cooled.

In the present embodiment, the so-called corotron is used as the charger 60, but the charging device 60 is not limited to this. For example, as the charger 60, a so-called scorotron having a grid may be used.

In the present embodiment, the gripper 54 as an example of the holding portion holds the front end portion of the recording medium P, but the present invention is not limited to this. For example, as an example of the holding portion, as shown in FIG. 8, grippers 154, 155, and 156 that hold the side end portions of the recording medium P may be used. In this configuration, the grippers 154, 155, and 156 hold the recording medium P outside the region GR where the toner image of the recording medium P is transferred. Also in this configuration, when the recording medium P is conveyed, the grippers 154, 155, and 156 pass through the nip region 28A in a side view. In FIG. 8, the chain 52 is shown in a simplified manner. FIG. 8 shows a state in which the recording medium P is conveyed between the sprocket 29 and the sprocket 19.

The holding portion may be composed of only the gripper 154 that holds the front end side of the recording medium P. The front end side of the recording medium is a portion of the recording medium on the downstream side (front side) from the center in the transport direction.

In the present embodiment, the chain 52 is used as an example of the orbiting member, but the present invention is not limited to this. For example, as an example of the orbiting member, a timing belt may be used. In the present embodiment, the sprocket 29 is used as an example of the first rotating body, but the present invention is not limited to this. For example, as an example of the first rotating body, a timing pulley around which a timing belt is wound may be used. When a timing pulley is used as an example of the first rotating body, a timing pulley is used instead of the sprocket 19 as an example of the second rotating body. Further, timing pulleys are used instead of sprockets 46, 47 and 48.

In the present embodiment, the charger 60 is used as an example of the facing portion, but the present invention is not limited to this. For example, as an example of the facing portion, a facing roll that contacts the transfer belt 24 may be used.

In the present embodiment, the heating roll 68 is used as an example of the heating unit, but the present invention is not limited to this. For example, as an example of the heating unit, a heating belt in contact with the pressure roll 69 may be used.

In the present embodiment, the heater 74 is used as an example of the non-contact heating unit, but the present invention is not limited to this. For example, a halogen lamp may be used as an example of the non-contact heating unit.

In the present embodiment, the transfer cylinder 28 is rotationally driven to rotate the chain 52, but the present invention is not limited to this configuration. For example, the pressurizing roll 69 may be rotationally driven to rotate the chain 52 with the transfer cylinder 28 as a driven rotation, or the transfer cylinder 28 and the pressurizing roll 69 may be synchronized with each other to orbit the chain 52. You may. The pressure roll 69 and the transfer cylinder 28 may be driven to rotate, and the other sprockets may be rotationally driven to rotate the chain 52.

In the present embodiment, the chain 52 is wound around the sprockets 19, 29, 46, 47, 48, but the present invention is not limited to this configuration. For example, the chain 52 may be wound only on the sprockets 19 and 29 without providing the sprockets 46, 47 and 48.

In the present embodiment, the present invention is applied to the electrophotographic image forming apparatus 10, but the present invention is not limited to this configuration, and the present invention is applied to a known image forming apparatus other than the electrophotographic type. May be good. For example, the present invention may be applied to an inkjet image forming apparatus. In this case, the image forming unit has an inkjet head as an example of a forming unit that ejects droplets onto the recording medium P supported by the rotating cylinder to form an image on the recording medium P, and the fixing unit has an inkjet head. It has a drying portion for drying the droplets discharged to the recording medium P.

The present invention is not limited to the above-described embodiment, and various modifications, changes, and improvements can be made within a range that does not deviate from the gist thereof. For example, the above-mentioned modified examples may be configured by combining a plurality of them as appropriate.
This application claims priority based on Japanese Patent Application No. 2019-171943 dated September 20, 2019.

Claims (10)

1. An image forming unit having a first body supporting a recording medium and a first rotating body arranged at an axial end of the first body, and forming an image on the recording medium.
   It has a second body that supports the recording medium and a second rotating body that is arranged at the axial end of the second body, and the image is recorded on the recording medium by heating or drying the recording medium. And the fixing part to be fixed to
   An orbiting member that is stretched over the first rotating body and the second rotating body and orbits with the rotation of the first rotating body and the second rotating body, and is attached to the orbiting member to hold the recording medium. A transporting portion that has a holding portion for carrying the recording medium from the image forming portion to the fixing portion by rotating the rotating member.
   An image forming apparatus comprising.
2. The image forming apparatus according to claim 1, wherein the rotating member is wound around the first rotating body and the second rotating body.
3. The maximum width of the transport portion in the width direction of the image forming apparatus is the length from the portion where the circumferential member is wound around the first rotating body to the portion wound around the second rotating body. The image forming apparatus according to claim 2.
4. The image forming portion further has an annular transfer belt on which the image is transferred to the outer surface.
   The first cylinder is a transfer cylinder having a transfer region for transferring the image from the transfer belt to the recording medium by sandwiching the recording medium with the outer surface of the transfer belt.
   The fixing portion further has a heating portion and has a heating portion.
   The second body is a pressure roll having a fixing region for fixing an image on the recording medium by sandwiching the recording medium with the outer surface of the heating portion.
   The image forming apparatus according to any one of claims 1 to 3, wherein the transport unit transports the recording medium by orbiting the orbiting member and passes through the transfer region and the fixing region.
5. The fourth aspect of the present invention further comprises a non-contact heating unit provided between the image forming unit and the fixing unit in the transport direction of the recording medium to heat the image transferred to the recording medium in a non-contact manner. Image forming device.
6. Further, a blower portion that faces the non-contact heating portion with the orbiting member sandwiched therein and blows air to the back surface of the recording medium conveyed by the transfer portion on the side opposite to the surface on which the image is transferred. The image forming apparatus according to claim 5.
7. The image forming apparatus according to any one of claims 4 to 6, wherein the outer diameter of the first rotating body is smaller than the outer diameter of the transfer cylinder.
8. The image forming apparatus according to any one of claims 4 to 6, wherein the transfer cylinder has a base material and a surface layer wound around the base material and exchangeable with respect to the base material.
9. The image forming apparatus according to any one of claims 4 to 8, wherein the outer diameter of the second rotating body is smaller than the outer diameter of the pressure roll.
10. The image forming apparatus according to any one of claims 4 to 9, wherein the pressure roll has a base material and a surface layer wound around the base material and exchangeable with respect to the base material. ..

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