JP2018041057A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible, when paper jam occurs during conveyance of transfer paper from a relay conveyance unit to a fixing unit, to adjust the exit height of a conveyance part belt of the relay conveyance unit at an appropriate height.SOLUTION: An image forming apparatus comprises: height changing means 90; a transfer paper detection sensor 75 that detects a leading end of a transfer material, such as transfer paper P ejected from an exit 22x of a conveyance part belt 22 being bent toward a first surface (rear face of transfer material); and a control part 50 that, at the occurrence of paper jam between a transfer unit and a fixing unit, when detecting the leading end of the transfer material being bent toward the first surface on the basis of a result of detection from a transfer paper detection sensor 75, displaces the height of the exit in a direction from the first surface toward a second surface (front face of transfer material) of the transfer material, and when not detecting the leading end of the transfer material being bent toward the first surface, controls the height changing means 90 to displaces the height of the exit to a direction toward the second surface of the transfer material.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an image forming apparatus.

  In an electrophotographic image forming apparatus, when a toner image on an image carrier is transferred onto a transfer material such as transfer paper or a recording medium and conveyed to a fixing unit which is a fixing unit, a conveyance belt is provided as a conveyance member. There is known a method using a relay transfer unit configured as described above.

  In such an image forming apparatus, in general, when a transfer material is conveyed from the relay conveyance unit to the fixing unit, an exit height of the relay conveyance unit or an inlet of the fixing unit is prevented so that abnormal images and jams such as transfer dust and paper wrinkles do not occur. A technique for adjusting the height of the lens is already known. Examples of this type of technology include Patent Documents 1 and 2.

  However, with the conventional method of adjusting the exit height of the relay conveyance unit and the entrance height of the fixing unit, when an abnormal image or jam occurs, it is easy to see how the adjustment can be improved. There was a problem of not knowing. For example, even if the transfer material behavior is disturbed while transporting from the relay transport unit to the fixing unit and a jam occurs, the exit height (exit position) of the transport belt (transport member) of the relay transport unit can be lowered to prevent it. I couldn't easily tell if it should be better or not.

  In the present invention, when a transfer material is transported from a relay transport unit to a fixing unit, when a jam occurs due to a disturbance in the behavior of the transfer material, the exit position of the transport member of the relay transport unit can be improved. The purpose is to enable adjustment to an appropriate height.

  In order to achieve the above object, the present invention provides a transfer unit that transfers a toner image on an image carrier to a transfer material, a fixing unit that fixes a toner image on the transfer material, the transfer unit, and the fixing unit. A relay conveying unit having a conveying member that conveys the transfer material between them, a position changing means for changing the position of the outlet of the downstream end of the conveying member in the transfer material conveying direction, and the transfer that has exited from the outlet of the conveying member A transfer material detecting means for detecting that the leading edge of the material warps to the first surface side, and a case where a jam occurs between the transfer unit and the fixing unit, from the transfer material detecting means. Based on the detection result, when it is detected that the tip of the transfer material is warped toward the first surface, the position of the outlet is moved in the direction from the first surface to the second surface of the transfer material. The tip of the transfer material is on the first side An image forming apparatus comprising: a control unit that controls the position changing unit to move the position of the exit in a direction from the second surface of the transfer material to the first surface when warping is not detected. It is.

  According to the present invention, when a transfer material is conveyed from the relay conveyance unit to the fixing unit, when a jam occurs due to a disturbance in the behavior of the transfer material, it is easy to determine how the exit position of the conveyance member can be improved. Thus, the exit position can be adjusted to an appropriate position accordingly.

1 is a schematic cross-sectional view of an entire image forming apparatus according to Embodiment 1 of the present invention. FIG. 2 is a cross-sectional view of a main part for explaining the behavior / posture state of a transfer paper leading end portion, together with detailed configurations of a relay conveyance unit, a height changing unit, and a fixing unit of Embodiment 1. FIG. 3 is a perspective view of the relay conveyance unit, the height changing unit, and the fixing unit according to the first embodiment when viewed from the front upper side of the paper. It is a front view which shows the shape of the cam used for the height change means of Embodiment 1. FIG. 5 is a cross-sectional view of a main part for explaining the height adjustment of the exit of the transport belt of the relay transport unit according to the first embodiment. 2 is a control block diagram illustrating a control configuration of Embodiment 1. FIG. 3 is a flowchart illustrating a control operation according to the first embodiment. It is sectional drawing of the principal part which shows typically the relay conveyance unit of a modification 1, a height change means, etc. FIG. 10 is a perspective view of a relay conveyance unit and a fixing unit according to Modification 2 as viewed from the front upper side of the sheet. FIG. 10 is a cross-sectional view of a main part for explaining the behavior / posture state of a leading end portion of a transfer paper, together with detailed configurations of a relay conveyance unit, a height changing unit, and a fixing unit of Embodiment 2. It is a front view which shows the shape of the cam used for the height change means of Embodiment 2. It is sectional drawing of the principal part explaining the height adjustment of the exit of the conveyance belt of the relay conveyance unit of Embodiment 2. 6 is a control block diagram illustrating a control configuration of Embodiment 2. FIG. 6 is a flowchart illustrating a control operation according to the second embodiment. It is sectional drawing of the principal part explaining the height adjustment of the exit of the conveyance belt of the relay conveyance unit of Embodiment 3. FIG. 10 is a control block diagram illustrating a control configuration of a third embodiment. 10 is a flowchart illustrating a control operation according to the third embodiment. It is sectional drawing of the principal part explaining the height adjustment of the exit of the conveyance belt of the relay conveyance unit of Embodiment 4. FIG. 10 is a control block diagram illustrating a control configuration of a fourth embodiment. 10 is a flowchart illustrating a control operation according to the fourth embodiment.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention including examples will be described in detail with reference to the drawings. In each embodiment, components (members and components) having the same function, shape, and the like will be omitted by giving the same reference numerals after being described once unless there is a possibility of confusion. In order to simplify the drawings and the description, even if the components are to be represented in the drawings, the components that do not need to be specifically described in the drawings may be omitted as appropriate. When a constituent element such as a published patent gazette is cited and described, the reference numeral is attached with parentheses to distinguish it from the embodiment and the like.
Note that the term “arrangement” used in this specification refers to disposition or provision of a position, engagement with “engagement”, and engagement with “locking”. In this case, “contact” means to contact the abutting state.

(Embodiment 1)
The basic configuration and operation of the image forming apparatus according to the first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view of the entire image forming apparatus according to Embodiment 1 of the present invention.
As shown in FIG. 1, the image forming apparatus 100 includes a transfer unit 2, a paper feeding device 1, an image forming unit 4, an optical scanning device 5, a transfer conveyance device 6, a fixing unit 7, a belt cleaning device 8, and a registration roller pair 12. The printer includes a control unit 50 and the like, and performs image formation by an electrophotographic method.
The transfer unit 2 includes an intermediate transfer belt 3 as an intermediate transfer body for transferring a toner image onto a transfer paper P as an example of a transfer material. The paper feeding device 1 is configured to supply the transfer paper P toward the intermediate transfer belt 3. The image forming unit 4 has a configuration for forming toner images of respective colors to be described later on the intermediate transfer belt 3.

  The optical scanning device 5 has a configuration that optically scans a photoconductor 40 as an image carrier in the image forming unit 4. The transfer conveyance device 6 has a configuration for conveying the toner image on the intermediate transfer belt 3 while performing secondary transfer onto the transfer paper P in contact with the secondary transfer nip N2. The fixing unit 7 is configured to fix the toner image on the transfer paper P using heat and pressure. The belt cleaning device 8 is configured to remove toner remaining on the intermediate transfer belt 3 without being transferred to the transfer paper P at the secondary transfer nip N2. The registration roller pair 12 has a configuration in which the transfer paper P is sent out at a timing toward the secondary transfer nip N2.

  The image forming unit 4 includes image forming units 4Y, 4M, 4C, and 4K for forming yellow (Y), magenta (M), cyan (C), and black (K) toner images. These image forming units 4Y, 4M, 4C, and 4K have substantially the same configuration except that the color of the toner to be used is different. Hereinafter, the image forming unit 4K that forms a K toner image will be described, but the image forming units 4Y, 4M, and 4C for other colors have the same configuration.

  The image forming unit 4K includes a latent image carrier that rotates in the direction of arrow A in the figure or a photoconductor 40 that is an image carrier, a charging device 41 that uniformly charges the photoconductor 40 to a negative polarity, and a static eliminator that neutralizes the photoconductor 40. Equipment. The image forming unit 4K also includes a developing device 42 that develops the electrostatic latent image written on the photoconductor 40 by the optical scanning device 5 to obtain a toner image. Further, the image forming unit 4K has a cleaning device 43 for cleaning the transfer residual toner adhering to the photoconductor 40 after passing through the primary transfer nip N1 due to the contact between the intermediate transfer belt 3 and the photoconductor 40. doing.

The optical scanning device 5 is disposed above the image forming unit 4, and irradiates a laser beam modulated according to image information toward the photoconductor 40, thereby forming an electrostatic latent image on the surface of the photoconductor 40. Write.
The photoreceptor 40 is uniformly charged to a negative polarity by the charging device 41 after the surface potential is initialized by the charge removal by the charge removal device. The surface of the uniformly charged photoreceptor 40 is optically scanned by the optical scanning device 5 and carries an electrostatic latent image.

  The developing device 42 develops the electrostatic latent image by attaching toner to the electrostatic latent image formed on the surface of the photoreceptor 40 to obtain a K toner image. The K toner image that has passed through the position facing the developing device 42 as the photoconductor 40 rotates enters the primary transfer nip N <b> 1 due to the contact between the photoconductor 40 and the intermediate transfer belt 3. In the primary transfer nip N1, a positive primary transfer bias is applied to the primary transfer roller 18 that sandwiches the intermediate transfer belt 3 between the photoreceptor 40 and a transfer electric field is formed. Has been. The K toner image on the photoreceptor 40 is primarily transferred onto the front surface of the intermediate transfer belt 3 by the action of the transfer electric field and the nip pressure.

The cleaning device 43 removes transfer residual toner adhering to the surface of the photoreceptor 40 after passing through the primary transfer nip N1 from the surface of the photoreceptor 40.
The intermediate transfer belt 3 is an endless belt that moves endlessly in the direction of arrow B in the drawing while being stretched by a driving roller 31, a tension roller 32, a support roller 34, and a repulsive roller 35 disposed inside the loop. It is. Each of the drive roller 31, the tension roller 32, the support roller 34, and the repulsive roller 35 has an aluminum cylindrical core and a silicone rubber layer formed on the outer periphery of the cylinder.

  The intermediate transfer belt 3 moves endlessly in the direction of arrow B in the figure as the driving roller 31 is rotationally driven by the driving source. The structure of the intermediate transfer belt 3 may be either a multilayer structure or a single layer structure, but in the first embodiment, a multilayer structure having a surface layer and a base layer is adopted. When the intermediate transfer belt 3 has a multi-layer structure, the base layer is made of, for example, a fluororesin, PVDF sheet, or polyimide resin that has little elongation, and a surface layer is formed on the surface that contacts the transfer paper P in the secondary transfer nip N2. It is preferable to provide a coat layer with good smoothness such as a fluororesin. In the case of a single layer structure, it is preferable to use a material such as PVDF, PC, or polyimide.

The sheet feeding device 1 includes a sheet feeding roller 11 that conveys the transfer sheet P stored and held on a sheet feeding tray toward the registration roller pair 12. Note that the paper feeding device 1 is not limited to this, and includes, for example, a plurality of paper feeding cassettes as shown in FIG. 1 of Patent Document 2, and the size of the transfer paper and the type of transfer paper stored in these paper feeding cassettes. The transfer paper brand may be selectively instructed by the operation unit and fed. Further, not only the paper feed roller 11 as the feeding means but also a paper feed roller and a separation roller may be provided.
The registration roller pair 12 temporarily stops driving when the transfer paper P supplied from the paper feeding device 1 is sandwiched between the rollers, and then synchronizes with the toner image on the intermediate transfer belt 3 in the secondary transfer nip N2. The driving is resumed and the transfer paper P is sent out.

The transfer conveying device 6 is configured so that the endless secondary transfer belt 60, the secondary transfer roller 62 and the separation roller 61 that stretch the belt inside the loop of the secondary transfer belt 60, and the secondary transfer belt 60 are returned. It has a misalignment correcting means for correcting. Other configurations such as the material of the secondary transfer belt 60 are the same as those of the intermediate transfer belt 3.
The secondary transfer roller 62 disposed inside the loop of the secondary transfer belt 60 is rotationally driven while sandwiching the two belts with the repulsive roller 35 disposed inside the loop of the intermediate transfer belt 3. As a result, the secondary transfer belt 60 is moved endlessly in the direction of arrow C in the figure. A region where the two belts are in contact with each other as described above is a secondary transfer nip N2.
Note that the transfer conveyance device 6 is not an essential component of the present invention and may be omitted.

  The separation roller 61 is formed of a cylindrical roller, and is rotated along with the movement of the secondary transfer belt 60. The separation roller 61 separates the transfer paper P held on the front surface of the secondary transfer belt 60 from the secondary transfer belt 60 by rapidly changing the traveling direction of the secondary transfer belt 60 according to its curvature. To do. The separated transfer paper P is transferred toward the fixing unit 7.

  The fixing unit 7 includes a heating roller 71 having a heat source such as a heater in order to heat the transfer paper P, and a pressure roller 72 that forms a fixing nip N in contact with the heating roller 71. . The heating roller 71 includes an aluminum cylindrical roller, a silicone rubber layer formed on the outer periphery of the cylinder, and a halogen heater as a heat source / heater disposed inside the cylinder. The configuration of the pressure roller 72 is the same as that of the rollers such as the driving roller 31, the tension roller 32, the support roller 34, and the repulsive roller 35 described above, and a description thereof will be omitted.

  The belt cleaning device 8 removes transfer residual toner adhering to the intermediate transfer belt 3 after passing through the secondary transfer nip N2. The belt cleaning device 8 is provided with a blade-shaped cleaning blade 37 made of urethane or the like, and the cleaning blade 37 scrapes off transfer residual toner attached to the intermediate transfer belt 3. As a cleaning member of the belt cleaning device 8, instead of the cleaning blade 37, for example, a conductive fur brush may be used to remove the transfer residual toner by an electrostatic cleaning method.

The operation of the image forming apparatus 100 will be described while supplementing the configuration other than the above. The operation of the image forming apparatus 100 is performed under the control of the control unit 50 disposed in the apparatus main body 99.
When image information is given from a terminal such as a personal computer or a scanner connected to the image forming apparatus 100, the optical scanning device 5 optically scans the Y, M, C, and K photoconductors 40 based on the image information. To form an electrostatic latent image. These electrostatic latent images are developed by the developing device 42 to become Y, M, C, and K toner images, and then superimposed on the front surface of the intermediate transfer belt 3 at the primary transfer nip N1 to be primary. Transcribed. In the monochrome mode, only the image forming unit 4K for K is used with the belt tension changed so that the intermediate transfer belt 3 is separated from the Y, M, and C photoconductors 40. By driving, only the K toner image is formed on the front surface of the intermediate transfer belt 3.

In parallel with the formation of the toner image on the front surface of the intermediate transfer belt 3, the transfer paper P stored in the paper feed tray is arranged on the downstream side of the paper feed path 10 by the rotation of the paper feed roller 11. It is conveyed via a conveying roller provided, and conveyed to the registration roller pair 12. The registration roller pair 12 sends the transfer paper P toward the secondary transfer nip N2 at an appropriate timing to synchronize with the toner image on the intermediate transfer belt 3.
In the secondary transfer nip N2, a secondary transfer electric field is formed by a secondary transfer bias applied to the repulsive roller 35. The toner image on the intermediate transfer belt 3 is secondarily transferred onto the transfer paper P fed into the secondary transfer nip N2 by the action of a secondary transfer electric field and nip pressure. When the transfer paper P that has passed through the secondary transfer nip N2 is peeled off from the secondary transfer belt 60 by the separation roller 61, a relay conveyance unit 9 (described later) provided downstream of the separation roller 61 in the transfer material conveyance direction X is provided. It is conveyed to. Further, the transfer paper P is transported toward the fixing nip N of the fixing unit 7 along the fixing inlet guide plate 73 as a guide member by the transport of the relay transport unit 9.
The detailed configuration and operation around the relay conveyance unit 9 and the fixing unit 7 which are characteristic portions of the first embodiment will be described in detail later with reference to FIGS.

The transfer paper P fed into the fixing unit 7 is heated and pressed by the heating roller 71 and the pressure roller 72 in the fixing nip N which is a pressure contact / nip portion between the heating roller 71 and the pressure roller 72. Is done. The toner image held on the surface of the transfer paper P is fixed as an image by the heating / pressurizing step.
The transfer sheet P on which the image is fixed is discharged to a discharge tray 17 outside the image forming apparatus 100 by a pair of discharge rollers 16. Note that the image forming apparatus 100 may be provided with a conveyance path for double-sided printing for reversing the transfer sheet P after fixing and retransmitting it to the registration roller pair 12 (see, for example, FIG. 1 of Patent Document 2). ).

  A detailed configuration of the fixing unit 7 including the relay conveyance unit 9 and the fixing inlet guide plate 73 will be described with reference to FIGS. 2 and 3. FIG. 2 is a cross-sectional view of the main part for explaining the behavior and posture state of the leading end of the transfer paper, together with the detailed configurations of the relay transport unit 9, the height changing means 90, and the fixing unit 7, and FIG. FIG. 4 is a perspective view of the height changing unit 90 and the fixing unit 7 as viewed from above the front side of the paper.

  The relay conveyance unit 9 includes a conveyance belt 22 as a conveyance member that conveys the transfer paper P between the transfer conveyance device 6 disposed below the transfer unit 2 illustrated in FIG. 1 and the fixing nip N of the fixing unit 7. Have. The relay conveyance unit 9 includes a driving roller 20, a driven roller 21, a conveyance belt 22, a unit frame 23, and the like, and is integrally coupled and held by the unit frame 23.

The drive roller 20 is integrally formed with the unit frame 23 and a shaft 20a rotatably supported by the apparatus main body 99 of FIG. 1, and is held by the apparatus main body 99 so that its position does not change. As schematically shown in FIG. 2, a belt driving motor 24 is connected to the shaft 20a of the driving roller 20 via an appropriate driving force transmission means such as a gear or by direct connection. The driven roller 21 is configured integrally with a shaft 21a that is rotatably supported by the unit frame 23, and is configured to be swingable with the shaft 20a of the driving roller 20 together with the unit frame 23 by a height changing means 90. Has been.
The conveyor belt 22 is endlessly moved in the counterclockwise direction in the figure by being stretched between the driving roller 20 and the driven roller 21 while being applied with tension. As shown in FIG. 3, a plurality of conveying belts 22 (two in the first embodiment) are provided in the width direction Y orthogonal to the transfer material conveying direction X, and both sides on the outer side of the conveying belt 22 are unit frames. 23. The upper surface of the conveyance belt 22 is a transfer material conveyance surface 22a.

A transfer material suction fan similar to the paper suction fan (78) shown in FIG. 4 of Patent Document 2 is provided inside the conveyance belt 22 between the driving roller 20 and the driven roller 21. A number of holes 22b are formed in the conveying belt 22 as shown in part of FIG. 3, and the transfer paper P is sucked and held on the transfer material conveying surface 22a of the conveying belt 22 by the air current of the transfer material adsorption fan. In addition, the transfer paper P can be reliably conveyed.
As described above, the relay conveyance unit 9 is configured such that the outlet 22x side at the downstream end of the conveyance belt 22 in the transfer material conveyance direction X can swing around the shaft 20a.
As shown in FIG. 3, the transfer paper P held and conveyed by the conveyance belt 22 is transferred to the transfer material conveyance surface at a position between the pair of conveyance belts 22 in the middle of the relay conveyance unit 9 in the width direction Y. A pair of transfer paper separating plates 25 for separating from 22a is provided. The transfer paper separating plate 25 protrudes further downstream from the downstream end of the transfer belt 22 in the transfer material conveyance direction X, and is formed along the transfer material conveyance direction X.

The fixing unit 7 includes a fixing inlet guide plate 73, a spur 74, and a transfer paper detection sensor 75 in addition to the heating roller 71 and the pressure roller 72.
The fixing entrance guide plate 73 functions as a guide member having a transfer material guide surface 73 a that guides the transfer paper P conveyed by the relay conveyance unit 9 to the fixing nip N of the fixing unit 7.
The spur 74 has a function of preventing the trailing edge of the transfer paper from being splashed, and a large number of fine protrusions are formed on the outer peripheral portion of the roller-shaped member. It is configured to be rotatable.

The transfer paper detection sensor 75 functions as a transfer material detection unit that detects that the leading edge Pa of the transfer paper P that has exited from the outlet 22x of the conveyor belt 22 warps toward the first surface (the back surface of the transfer paper). Hereinafter, the phenomenon in which the leading edge of the transfer paper warps toward the first surface (the back surface of the transfer paper) is referred to as “back curl”. The phenomenon that warps the front side is called “face curl”.
More specifically, the transfer paper detection sensor 75 is a behavior of the transfer paper P including the back curl BC between the vicinity of the exit 22 x of the transport belt 22 and the vicinity of the entrance 73 x of the fixing entrance guide plate 73 in the relay transport unit 9. The state is detected. The behavior state of the transfer paper P includes the posture state of the transfer paper P. As the transfer paper detection sensor 75, a light reflection type photo sensor is used.
Here, the exit 22x of the transport belt 22 strictly means the downstream end of the transfer material transport surface 22a formed on the transport belt 22 of the relay transport unit 9 in the transfer material transport direction X. Strictly speaking, the inlet 73x of the fixing inlet guide plate 73 means the upstream end of the transfer material guide surface 73a in the transfer material conveyance direction X.

  The ideal transfer paper is NC with no curling, like the transfer paper P shown by the solid line in FIG. However, the back curl BC indicated by the alternate long and short dash line and the face curl indicated by the broken line, particularly at the leading end portion including the leading end Pa of the transfer paper, depending on the storage environment and handling method of the transfer paper P, the second side of double-sided printing, etc. FC may occur. The back curl BC tends to occur on the second surface during double-sided printing due to the difference in the degree of expansion and contraction of the paper fibers that the front and back surfaces for double-sided printing receive in the heating / pressurizing process of the fixing unit 7. As shown in FIG. 2, when a back curl BC in which the leading edge Pa of the transfer paper P warps toward the first surface (the back surface of the transfer paper) occurs, the leading edge Pa of the transfer paper P is connected to the relay conveyance unit 9. The fixing sheet 7 is caught in a gap between the fixing entrance 7 and the fixing entrance 7 and the behavior of the transfer sheet P is disturbed, and a jam occurs. In addition, when a face curl FC occurs in which the leading edge Pa of the transfer paper P is warped toward the second surface (the front surface of the transfer paper), the leading edge Pa of the transfer paper P is caught by the spur 74 and the transfer paper P Behavior is disturbed and jam occurs.

  Therefore, in the first embodiment of the present invention, when a transfer paper jam occurs, it is determined from the detection result of the transfer paper detection sensor 75 which of the two types of transfer paper is disturbed. And based on the result, it was set as the structure which adjusts the exit height as an exit position of the relay conveyance unit 9 (conveyance belt 22) to suitable exit height using the height change means 90. FIG. Hereinafter, the height changing unit 90 and a control configuration for controlling the height changing unit 90 will be described.

The height changing means 90 changes the height of the outlet 22x of the conveyor belt 22 (hereinafter also referred to as “the outlet height of the relay conveyor unit 9”) as an example of the position of the outlet 22x of the conveyor belt 22. is there.
The height changing means 90 includes a cam 91 for changing the outlet height of the relay conveyance unit 9, a cam motor 92 schematically shown as a drive source connected to the cam shaft 91a, and a height position of the cam 91. And a support plate 93 fixed to the apparatus main body 99 of FIG. 1 as a positioning base. The support plate 93 is also a base member.

As shown in FIG. 3, the cam 91 and the support plate 93 are respectively disposed on both outer sides in the width direction Y across the conveyance belt 22. The pair of cams 91 are plate cams, and are connected by a cam shaft 91a extending in the width direction Y so that cam surfaces described later on the outer periphery of the contour rotate with the same phase and the same cam surface held. . Note that the cam 91 and the support plate 93 are not limited to the configuration shown in FIG. 3, and may be a single one provided on one outer side in the width direction Y across the conveyance belt 22.
As shown in FIG. 4, the cam 91 is formed so that the exit height of the relay transport unit 9 can be changed, and can be switched between three levels of low 91l, medium 91m, and high 91h. The cam surface is set to 91m in the middle. The cam 91 is integrally formed with a cam surface of a base 91b that is a portion that comes into contact with the support plate 93 so as to face each of the low 91l, medium 91m, and high 91h cam surfaces.

  The position of the cam 91 shown in FIGS. 2 and 3 is a state in which the default 91m cam surface is in contact with the lower surface 23d of the unit frame 23, whereby the exit height of the relay transport unit 9 is the default. : Indicates that it is in the middle height position. In FIG. 3, in order to make the position of the cam 91 easy to see, the cam surface of the middle 91 m is intentionally shifted from the state in contact with the lower surface 23 d of the unit frame 23 to the outside in the width direction Y. Is noted.

Jam detection sensors 77 and 78 functioning as jam detection means for detecting a jam of the transfer paper P are disposed on the upstream side and the downstream side in the transfer material conveyance direction X in the fixing unit 7. The jam detection sensors 77 and 78 are light reflection type photosensors, and are attached to the unit side plate of the fixing unit 7.
In the first embodiment, as described above, the jam detection sensors 77 and 78 are provided on both the upstream side and the downstream side in the transfer material conveyance direction X in the fixing unit 7. You may provide in either.

  FIG. 5 is a cross-sectional view of a main part for explaining the height adjustment of the outlet 22x of the conveyor belt 22. As shown in FIG. As shown in the figure, when the cam motor 92 is driven and the cam surface of the cam 91 is changed from the default middle 91 m shown by the solid line in FIG. 5 to the low 91 l shown in FIG. 4, the height of the outlet 22 x of the conveyor belt 22 is increased. Becomes lower, and the exit height is 22 × L as indicated by the alternate long and short dash line. When the cam motor 92 is further driven to raise the cam surface of the cam 91 to a height of 91h, the height of the outlet 22x of the conveyor belt 22 is increased to the position of the outlet height 22xH indicated by a broken line.

The control configuration of the first embodiment will be described with reference to FIG. FIG. 6 is a control block diagram illustrating a control configuration of the first embodiment.
In FIG. 6, the control unit 50 functions as a broadly defined control unit that controls the image forming operation and the operation of the height changing unit 90. The control unit 50 includes a microcomputer including a CPU 51 having functions of an arithmetic means and a control means in a narrow sense, a RAM 52, a PROM 53, and a timer 54 as a time measuring means. The RAM 52 temporarily stores calculation results of the CPU 51 and various data.

The PROM 53 functions as a first storage unit that stores a detection history of a jam of the transfer paper P that occurs between the relay conveyance unit 9 and the fixing unit 7. The PROM 53 also serves as a second storage unit that stores information about the transfer paper acquired by the transfer material information acquisition unit 47 in accordance with the changed outlet height of the relay conveyance unit 9 (conveyance belt 22). Function.
The PROM 53 stores a necessary control program (see FIG. 7 described later), fixed data, and the like in advance and is configured to be programmable. The PROM 53 is not limited to this, and may be a nonvolatile memory such as an EPROM or an EEPROM. The first storage means is not limited to the PROM 53 but may be a ROM.

The transfer paper detection sensor 75, the two jam detection sensors 77 and 78, and the transfer material information acquisition means 47 are connected to the CPU 51 of the control unit 50 via an input port, and via an output port and a motor driver. A cam motor 92 is connected. Further, the transfer material information acquisition unit 47 is connected to the CPU 51 via an input / output port. Here, as the control components connected to the CPU 51, only those closely related to the present invention are listed.
As the cam motor 92, a stepping motor is used. The CPU 51 of the control unit 50 instructs the cam motor 92 to output a predetermined number of drive pulses via the motor driver, so that the cam 91 is driven to rotate, and any of the above-described three stages of the cam surface. Is stopped at a predetermined rotational position.

  The transfer material information acquisition unit 47 acquires the type of transfer paper (transfer paper brand) as transfer material information. The transfer material information acquisition means 47 can be exemplified by an apparatus that acquires transfer sheet information for a brand of transfer sheet input by a user with respect to an operation unit including a touch panel or a numeric keypad or a double-sided printing key. Also included is double-sided printing operation activation information input by a double-sided printing key.

  Alternatively, transfer paper information sent from a personal computer or the like may be acquired. Further, a thickness detection unit that detects the thickness of the transfer paper and a size detection unit that detects the size of the transfer paper may be provided as the thickness information acquisition unit. Thickness detection means detects the thickness based on the result of detecting the transmittance of the transfer paper P with a light transmission type photosensor, or detects the amount of movement of the roller when the transfer paper is sandwiched between a pair of conveying rollers. The thing etc. which detect thickness based on a result can be illustrated.

The CPU 51 of the control unit 50 controls the cam motor 92 based on the detection results of the jam detection sensors 77 and 78 and the transfer paper detection sensor 75 and the information on the exit height of the relay conveyance unit 9 (conveyance belt 22) stored in the PROM 53. To control the outlet height of the relay transport unit 9.
That is, when a jam occurs, the CPU 51 changes the height based on the detection information from the transfer paper detection sensor 75 so that the exit height of the relay conveyance unit 9 is increased when the jam detection history is in the PROM 53. The cam motor 92 of the means 90 is controlled. The CPU 51 functions as a control unit that controls the cam motor 92 of the height changing unit 90 so that the exit height of the relay conveyance unit 9 is lowered when the jam detection history is not in the PROM 53.

  As described above, detection of whether or not the transfer paper P has normally passed through the fixing unit 7 (detection of jam) is performed by the jam detection sensors 77 and 78. The CPU 51 monitors the output signal of the jam detection sensor, and the jam detection sensors 77 and 78 do not detect the transfer paper P even if a predetermined time elapses after the transfer paper P is transferred to the secondary transfer nip N2. In this case, it is determined that a jam has occurred on the upstream side of the fixing unit 7. After detecting the occurrence of the jam, the CPU 51 follows the flow shown in FIG. 7 based on the presence / absence of the detection history of the transfer paper detection sensor 75 of the PROM 53, and the behavior state / posture of the transfer paper P (back curl BC or face curl FC). Judging. Based on this determination result, the cam motor 92 is driven to control the outlet height of the relay conveyance unit 9.

  A spur 74 in FIG. 2 is provided to prevent the rear end of the transfer paper P from jumping up after the transfer paper P has entered the fixing unit 7 and colliding with the surface of the heating roller 71. It has been. This prevents the occurrence of abnormal images. However, the spur 74 may be omitted. When the spur 74 is not provided, the transfer paper P that has undergone face curl FC in FIG. 2 collides with the surface of the heating roller 71, and the transfer paper P is not correctly transported to the fixing unit 7, and the transport behavior is disturbed and jamming occurs.

FIG. 7 shows information recorded in the PROM 53 (information on the height of the exit corresponding to the transfer paper brand) and the jam detection sensors 77 and 78 and the transfer paper detection sensor 75 under the control of the CPU 51 of the control unit 50. It is a figure which shows the flow which controls the exit height of the conveyance belt 22 based on a detection result.
First, in step S <b> 1 shown in FIG. 7, the transfer material information relating to the brand of the transfer paper to be passed is acquired from the transfer material information set by the transfer material information acquisition means 47. Next, it is determined and checked whether or not the exit height of the relay conveyance unit 9 (conveyance belt 22) corresponding to the acquired brand of transfer paper is stored in the PROM 53 (step S2). If the exit height corresponding to the brand of the transfer paper is not stored in the PROM 53, the process proceeds to step S3. In step S3, the cam 91 is rotationally driven by the cam motor 92 of the height changing means 90, and the exit height is set to a default height (positions of the relay conveyance unit 9 and the conveyance belt 22 shown by solid lines in FIG. 5). To do. In the flowchart of FIG. 7, “default” is described as “default” (the same applies to the flowchart described later).
On the other hand, when the exit height of the relay conveyance unit 9 (conveyance belt 22) corresponding to the acquired transfer paper brand is stored in the PROM 53 in step S2, the process proceeds to step S4, and the height changing means 90 performs the exit. Set the height to the stored height.

If the exit height is set, the printing operation (sheet passing operation) is started (step S5). After the printing operation (sheet feeding operation) is started, it is checked whether or not a jam has occurred at the fixing nip entrance of the fixing unit 7. (Step S6). If the jam detection sensors 77 and 78 detect the occurrence of a jam, the transfer paper P is stopped (step S7).
Whether or not the leading edge of the transfer paper P is caught in the gap between the relay conveyance unit 9 and the fixing entrance guide plate 73 of the fixing unit 7 that is generated when the back curl BC occurs when the jam occurs in the above portion. Is detected by the transfer paper detection sensor 75.

Next, the process proceeds to step S8, and it is checked whether or not the detection history of the transfer paper detection sensor 75 exists in the PROM 53. When the detection history of the transfer paper detection sensor 75 exists in the PROM 53, the transfer paper P undergoes back curl BC as shown in FIG. 2, and the leading edge of the transfer paper P is in the gap between the relay conveyance unit 9 and the fixing inlet guide plate 73. It can be seen that the behavior of the catching transfer paper P is disturbed and a jam has occurred. Based on this, the cam surface of the cam 91 is raised to 91h and raised to the position of the outlet height 22xH (see FIG. 5) of the relay conveyance unit 9 (conveyance belt 22) to increase the margin and prevent catching and jamming. (Step S9).
After the adjustment to the outlet height 22xH, the brand of the transfer paper P corresponding to the changed outlet height 22xH is input to the CPU 51 of the control unit 50, and the appropriate outlet height 22xH of the relay conveyance unit 9 (conveyance belt 22) is set. The brand of the transfer paper P is linked and stored in the PROM 53 (step S10). In this specification, “attach” means “relate” (the same applies hereinafter).

On the other hand, in step S8, when the detection history of the transfer paper detection sensor 75 is not in the PROM 53, the transfer paper P undergoes face curl FC as shown in FIG. It can be seen that jamming has occurred. Based on this, the cam surface of the cam 91 is lowered to 91 l and lowered to the position of the outlet height 22xL (see FIG. 5) of the relay conveyance unit 9 (conveyance belt 22) to increase the margin and prevent catching and jamming. (Step S11).
After the adjustment to the outlet height 22xL, the brand of the transfer paper P corresponding to the changed outlet height 22xL is input to the CPU 51 of the controller 50, and the appropriate outlet height 22xL of the relay transport unit 9 and the brand of the transfer paper P are entered. Is stored in the PROM 53 (step S12).

After the information is stored in the PROM 53 in step S10 or step S12, when the end of the jam processing by the user or the like is confirmed, the sheet passing operation is resumed. If no jam has occurred in step S6, the flow ends.
Note that if the printing does not end normally due to the occurrence of a jam, another image of the transfer sheet P may be passed again to print the image to be printed again.

By the operations of step S10 and step S12 described above, when the transfer paper P of the same brand is passed next, the exit height of the relay conveyance unit 9 can be adjusted to an appropriate height before the paper. As a result, it is possible to prevent jamming and improve productivity.
As described above, according to the first embodiment, when the transfer paper is transported from the relay transport unit to the fixing unit, when a jam occurs due to the disturbance of the transfer paper behavior, the exit height of the relay transport unit (transport belt) is increased. It is easy to see how this can be improved. And according to it, an exit height can be adjusted to suitable height.

In the first embodiment, the relay transport unit 9 is configured to be replaceable with respect to the apparatus main body 99 of FIG. 1 via fastening means such as screws. The transfer sheet detection sensor 75 is installed, that is, attached and fixed on the side surface of the fixing inlet guide plate 73 that faces the outlet of the relay conveyance unit 9, in other words, in the vicinity of the inlet of the fixing inlet guide plate 73.
With this configuration, according to the first embodiment, it is not necessary to frequently replace the transfer paper detection sensor 75 as compared with the case where the transfer paper detection sensor 75 is installed in the relay conveyance unit 9. There is also an effect that the work becomes easy.

(Modification 1)
A first modification of the first embodiment will be described with reference to FIG. FIG. 8 is a cross-sectional view schematically showing the relay conveyance unit 9A according to the first modification and the height changing means 90A for changing the overall height.
Compared with the first embodiment, the first modification mainly includes a point having a relay conveyance unit 9A instead of the relay conveyance unit 9 and a point having a height changing unit 90A instead of the height changing unit 90. Is different.
The relay transport unit 9A is configured so that the entire relay transport unit 9A can be displaced in the vertical direction Z so that the outlet side of the transport belt 22 and an inlet side to be described later are substantially parallel. In addition, the height changing means 90A changes the height of the outlet 22x as the relay transport unit 9A is displaced substantially parallel to the vertical direction Z. The entrance of the relay conveyance unit 9A (conveyance belt 22) is the upstream end of the transfer material conveyance surface 22a in the transfer material conveyance direction X.

  The shaft 20a of the driving roller 20 of the relay transport unit 9A and the shaft 21a of the driven roller 21 are fitted into grooves formed in the vertical direction Z formed on the pair of main body side plates on both sides in the width direction Y. Therefore, the position of the transfer material is regulated in the transfer material transport direction X and the width direction Y. The pair of main body side plates are fixed to the apparatus main body 99 of FIG. As described above, the relay conveyance unit 9A has the entire vertical conveyance unit 9 in the vertical direction so that the outlet 22x of the conveyance belt 22 and the inlet of the upstream end of the conveyance belt 22 in the transfer material conveyance direction X are substantially parallel. Z is configured to be displaceable. The belt drive motor 24 connected to the shaft 20a is fixed to a stationary member on the unit frame side of the relay transport unit 9A, and is displaced in the vertical direction Z together with the relay transport unit 9A.

The height changing means 90A includes a plurality of (two in the first modification) cams 91 having the same shape for changing the overall height of the relay conveyance unit 9A, and a drive gear fixed to the right cam shaft 91a in the drawing. 95 and a driven gear 97 fixed to the left camshaft 91a in the drawing. Further, as schematically shown in FIG. 8, the height changing means 90A is rotatably supported by the apparatus main body 99 of FIG. 1 via a gear shaft 96a and is engaged with the drive gear 95 and the driven gear 97. And a cam motor 92 connected to the right cam shaft 91a in the figure. The support plate 93A of the height changing unit 90A is formed so as to extend longer in the transfer material conveyance direction X than the support plate 93 of the first embodiment, corresponding to the plurality of cams 91. It is preferable that the height changing means 90 </ b> A is disposed on both outer sides in the width direction Y across the conveyance belt 22.
The height change means 90A using the cam 91 is not limited to the height change means using a parallel link link mechanism such as a pantograph and a drive means such as a drive motor for driving the parallel link link mechanism.

  Even when the above-described configuration of Modification 1 is used, the height of the outlet 22x of the conveyor belt 22 is indicated by a one-dot chain line by displacing the relay conveyor unit 9A in the vertical direction Z while maintaining the overall height of the relay conveyor unit 9A in parallel. The height can be set to an appropriate height position of 22xL or an outlet height 22xH indicated by a broken line.

(Modification 2)
A second modification of the first embodiment will be described with reference to FIG. FIG. 9 is a perspective view of the relay conveyance unit, the height changing unit, and the fixing unit according to the second modification viewed from the upper front side of the drawing.
The second modification has a relay transport unit 9B instead of the relay transport unit 9, and a fixing inlet guide plate 73B as a guide member instead of the fixing inlet guide plate 73, as compared with the first embodiment. Is different.
The fixing entrance guide plate 73B is different only in that the transfer paper detection sensor 75 is removed and that the fixing entrance guide plate 73B is configured to be replaceable via a fastening means such as a screw with respect to the apparatus main body 99 of FIG. Further, the relay conveyance unit 9B is different from the relay conveyance unit 9 only in that the transfer sheet detection sensor 75 is installed between the pair of transfer sheet separation plates 25, in other words, in the vicinity of the exit of the relay conveyance unit 9. Is different.
Modification 2 can also be applied to Modification 1.

  According to the second modification, the configuration described above has an effect that it is not necessary to frequently replace the transfer paper detection sensor 75, the cost can be reduced, and the replacement work is facilitated.

(Modification 3)
Modification 3 is different from Embodiment 1 and Modification 2 in that the fixing inlet guide plate and the relay conveyance unit are configured to be replaceable with respect to the apparatus main body 99, respectively. In addition, the transfer paper detection sensor 75 is different in that it is installed on the longer side of the replacement cycle between the fixing entrance guide plate and the relay conveyance unit.
Modification 3 can also be applied to Modification 1.

  Also according to the third modification, it is not necessary to frequently replace the transfer paper detection sensor 75 due to the above configuration, and the cost can be reduced and the replacement operation is facilitated.

  It should be noted that information relating to the replacement cycle of each of the relay conveyance unit and the fixing inlet guide plate (for example, the cumulative number of sheets passed after each member is attached) is preferably stored in the PROM 53 of the apparatus main body. If the number of sheets passed after attaching these members to the apparatus main body reaches a predetermined threshold value (a different threshold value for each of the relay conveyance unit and the fixing entrance guide plate), the control unit 50 replaces the above members on the apparatus main body. It is preferable to be configured to notify the user that it is time.

The transfer material of the present invention is not limited to transfer paper as an example, and any transfer material or transfer unit may be used as long as the toner image can be transferred. For example, thick paper, thin paper, envelope, postcard, coated paper, OHP film Of course, including sheets and the like.
In the first embodiment, the cam 91 that can switch the outlet height of the relay conveyance unit 9 in three stages is used. However, the present invention is not limited to this. That is, it is of course possible to use a cam that can switch the exit height of the relay conveyance unit 9 (conveyance belt 22) more finely and in multiple stages as necessary. Furthermore, not only the height changing means 90 using the cam 91 but also a height changing means using a screw mechanism or the like may be used.

As described above, the image forming apparatus according to the embodiment of the present invention is not limited to the first embodiment, and may be the first mode including only the essential configuration of the present invention.
That is, the first mode is a transfer unit such as a transfer unit 2 that transfers a toner image on an image carrier (or intermediate transfer member) such as an intermediate transfer belt 3 to a transfer material such as transfer paper P, and a transfer material on the transfer material. A fixing unit such as a fixing unit 7 for fixing a toner image; and a relay conveyance unit such as a relay conveyance unit 9 having a conveyance member such as a conveyance belt 22 for conveying a transfer material between the transfer unit and the fixing unit; Position changing means such as a height changing means 90 for changing the position of the outlet at the downstream end in the transfer material conveyance direction such as the transfer material conveyance direction X in the conveyance member, and the leading end of the transfer material from the outlet of the conveyance member Jam occurs between the transfer unit and the fixing unit, and a transfer material detection unit such as a transfer paper detection sensor 75 that detects that the first side (back surface of the transfer material) is warped. The position of the exit when it is detected that the leading edge of the transfer material warps toward the first surface (the back surface of the transfer material) based on the detection result from the transfer material detection means. Is moved in the direction from the first surface of the transfer material (the back surface of the transfer material) to the second surface (the front surface of the transfer material), and the tip of the transfer material is the first surface (the back surface of the transfer material) If it is not detected that the sheet is warped, the position of the outlet is moved in the direction from the second surface of the transfer material (the front surface of the transfer material) to the first surface (the back surface of the transfer material). In addition, the image forming apparatus includes a control unit such as a control unit 50 that controls the position changing unit.

  Using the terms of the first aspect, the configuration and operation of the first aspect will be supplemented while appropriately using the components of the first embodiment described above. When a jam occurs between the transfer unit and the fixing unit, the transfer material that has come out from the exit of the conveying member may be in the following two cases. That is, when the leading edge of the transfer paper is warped toward the first surface (the back surface of the transfer paper) (that is, downward in FIG. 2) from the regular transport path, the leading edge of the transfer paper is the second surface (transferring). There are two ways of warping to the side of the front surface of the paper (that is, upward in FIG. 2).

Therefore, (1) when the transfer material detection means (transfer paper detection sensor 75) detects that the leading edge of the transfer material is warped toward the first surface (back surface of the transfer paper), the control unit 50 causes the cam motor 92 to move. The cam 91 is rotationally driven as follows by driving control. That is, the position of the exit of the conveying member is moved in the direction from the first surface of the transfer material (the back surface of the transfer paper) to the second surface (the front surface of the transfer paper) (that is, upward in FIG. 2).
(2) On the other hand, when the transfer material detection means (transfer paper detection sensor 75) does not detect that the leading edge of the transfer material is warped toward the first surface (the back surface of the transfer paper), the control unit 50 detects the cam motor 92. Is driven as follows. That is, the position of the exit of the conveying member is moved in the direction from the first surface of the transfer material (the back surface of the transfer paper) to the second surface (the front surface of the transfer paper) (that is, upward in FIG. 2).
The timing for driving the cam motor 92 may be any time after a jam has occurred and until the next transfer paper is passed. It may be driven immediately after stopping the paper passing, or may be a timing during the returning operation after the jammed transfer paper is removed by the user.

In the case of (1) above, it can be determined that a jam has occurred because the transfer paper is back curled at the exit of the conveying member. Therefore, before passing the next transfer sheet, the position of the exit of the conveying member is moved in advance upward from the time when the jam occurs. As a result, even if the next transferred paper is back-curled in the same manner as the transfer paper at the time of jam occurrence, the fixing unit (the fixing entrance guide plate 73 of the fixing unit 7 in the first embodiment) is provided from the exit of the conveying member. It is easy to deliver the transfer paper to the paper, and jamming can be suppressed.
On the other hand, in the case of (2) above, it can be determined that a jam has occurred because the transfer paper is face-curled at the exit of the conveying member. Therefore, before passing the next transfer paper, the position of the exit of the conveying member is moved in advance downward than when a jam occurs. As a result, even if the next transfer sheet is face-curled in the same manner as the transfer sheet at the time of jam occurrence, the transfer sheet is transferred from the exit of the conveying member to the fixing unit (the fixing entrance guide plate 73 in the first embodiment). It becomes easy to deliver and jamming can be suppressed.

  Since the jammed transfer paper and the next transfer paper are stacked on the paper feeder 1 in the same temperature and humidity environment before the paper is passed, they may curl in the same direction. Many. For example, if the jammed transfer paper is back-curled at the exit of the conveying member, the transfer paper to be passed next is often back-curled as well. In the present embodiment, the position of the exit of the conveying member is determined based on the detection result of the transfer material detection means (transfer paper detection sensor 75) after the jam occurs and before the next transfer paper is passed after the jam processing is completed. To change. As a result, it is possible to suppress the occurrence of jam during the transfer of the transfer paper (and the subsequent sheets) to be passed next.

Depending on the type (brand) of the transfer paper to be passed, the direction in which the paper is easily curled (whether it is easy to back curl or face curl) differs. Therefore, it is preferable to store the brand of the transfer paper causing the jam and the detection result of the transfer material detection means (transfer paper detection sensor 75) in the PROM 53 for each transfer paper brand. The user of the image forming apparatus selects the type (brand) of the transfer paper to be used next by the touch panel or the numeric keypad (transfer material information acquisition unit 47).
The image forming apparatus reads the exit height corresponding to the brand of the transfer paper selected by the transfer material information obtaining unit 47 from the PROM 53, and the height changing unit 90 stores the exit height to the stored height. Set. By setting the exit height in this way, the exit height can be optimized for each type of transfer paper (brand), and jamming can be more reliably suppressed during transport. Can do.

(Embodiment 2)
In the first embodiment shown in FIGS. 1 to 7, only the presence / absence of whether or not the leading edge Pa of the back-curled transfer paper P is caught in the gap between the relay conveyance unit 9 and the fixing entrance guide plate 73 of the fixing unit 7 is detected. Therefore, it was not known how much the outlet of the relay transport unit 9 should be raised when caught.
Therefore, a second embodiment that can solve the above-described points to be improved of the first embodiment will be described with reference to FIGS. FIG. 10 is a cross-sectional view of a main part for explaining detailed configurations of the relay conveyance unit, the position changing unit, and the fixing unit of the second embodiment. FIG. 11 is a front view showing the shape of a cam used in the height changing means of the second embodiment. FIG. 12 is a cross-sectional view of a main part for explaining the height adjustment of the exit of the transport belt of the relay transport unit according to the second embodiment.

  In the second embodiment, a plurality of (two in the example of the second embodiment) transfer is used instead of the single transfer paper detection sensor 75 as compared with the image forming apparatus of the first embodiment shown in FIGS. The main points are that the paper detection sensors 75a and 75b are used, the relay transport unit 9C shown in FIG. 10 and the like is used instead of the relay transport unit 9, and the control unit 50C shown in FIG. Is different.

The transfer paper detection sensors 75a and 75b have a function of detecting that the leading edge Pa of the transfer paper P coming out from the outlet 22x of the conveyor belt 22 is warped toward the first surface (the back surface of the transfer paper: back curl BC). In addition, it functions as a transfer material detection means for detecting the amount of warpage in steps. That is, a plurality of transfer paper detection sensors 75a and 75b are arranged so that the leading edge Pa of the transfer paper P coming out from the outlet 22x of the conveyor belt 22 can detect the amount of warpage of the transfer paper P toward the first surface in a stepwise manner.
In the second embodiment, the two transfer paper detection sensors 75a and 75b are installed as the transfer material detection means. However, the present invention is not limited to this, and three or more transfer paper detection sensors may be installed.

More specifically, the transfer paper detection sensors 75a and 75b are arranged in order along the vertical direction Z, which is the direction in which the leading edge Pa of the transfer paper P coming out from the outlet 22x of the conveyor belt 22 warps toward the first surface. Has been placed. The transfer paper detection sensor 75a detects a relatively small back curl BC, and the transfer paper detection sensor 75b detects a relatively large back curl BC.
The transfer paper detection sensors 75a and 75b detect the behavior state of the transfer paper P including the back curl BC between the vicinity of the exit 22x of the transport belt 22 and the vicinity of the entrance 73x of the fixing entrance guide plate 73 in the relay transport unit 9. Is. As the transfer paper detection sensors 75a and 75b, light reflection type photo sensors are used.

The relay transport unit 9C is different from the relay transport unit 9 of FIGS. 2 and 3 in that a height changing unit 90C shown in FIGS. 10 and 12 is used instead of the height changing unit 90. The height changing unit 90C is different from the height changing unit 90 in that the cam 91C is used instead of the cam 91 and the support plate 93 is removed.
That is, as shown in FIGS. 10 and 12, the height changing means 90C includes a cam 91C for changing the outlet height of the relay conveyance unit 9C, and a cam motor 92 as a drive source connected to the cam shaft 91Ca. Have

Similarly to the cam 91 of the first embodiment, the cams 91 </ b> C are respectively disposed on both outer sides in the width direction Y across the conveyance belt 22. The pair of cams 91C are plate cams, and are connected by a cam shaft 91Ca that extends in the width direction Y so that a cam surface, which will be described later, of the outer periphery of the contour rotates in a state where the same cam surface is held in the same phase. . The cam 91C is not limited to the configuration shown in FIG. 10 and the like, and may be a single cam 91C provided on one outer side in the width direction Y across the conveyance belt 22.
As shown in FIG. 11, the cam 91C is formed as a cam surface capable of changing the exit height of the relay conveyance unit 9C so that it can be switched in four stages of low 91Cl, medium 91Cm, medium high 91Ch1, and high 91Ch2. The default cam surface is set at 91 Cm.

  The position of the cam 91C in FIGS. 10 and 12 is a state in which the default cam surface of 91Cm is in contact with the lower surface 23d of the unit frame 23, whereby the exit height of the relay transport unit 9 is the default. : Indicates that it is in the middle height position.

  In the second embodiment, when the jam of the transfer paper occurs, it is determined from the detection result of the transfer paper detection sensors 75a and 75b which of the two types of transfer paper is disturbed, and the transfer paper is detected. The amount of warpage to the first surface (back surface of transfer paper: back curl BC) of the leading edge Pa of P is detected stepwise. Based on the result, the height changing means 90C is used to adjust the outlet height as the outlet position of the relay conveying unit 9C (conveying belt 22) to an appropriate outlet height corresponding to the amount of warpage. did.

  FIG. 12 is a cross-sectional view of a main part for explaining the height adjustment of the outlet 22x of the conveyance belt 22 of the relay conveyance unit 9C according to the second embodiment. As shown in the figure, when the cam motor 92 is driven and the cam surface of the cam 91C is changed from the default medium 91Cm shown by the solid line in FIG. 12 to the low 91Cl shown in FIG. 11, the height of the outlet 22x of the conveyor belt 22 is increased. Becomes lower, and the exit height is 22 × L as indicated by the alternate long and short dash line. When the cam motor 92 is further driven to raise the cam surface of the cam 91C to the height 91Ch2, the height of the outlet 22x of the conveyor belt 22 is increased to the position of the outlet height 22xH2 indicated by the broken line. When the cam motor 92 is further driven to bring the cam surface of the cam 91C to the middle height 91Ch1, the height of the outlet 22x of the conveyor belt 22 is adjusted to the position of the outlet height 22xH1 indicated by a two-dot broken line.

The control configuration of the second embodiment will be described with reference to FIG. FIG. 13 is a control block diagram illustrating a control configuration of the second embodiment.
The control unit 50C according to the second embodiment is mainly different from the control unit 50 according to the first embodiment in that a CPU 51C is used instead of the CPU 51 and a PROM 53C is used instead of the PROM 53. In FIG. 13, the control unit 50C functions as a broadly defined control unit that controls the image forming operation and the operation of the height changing unit 90C. The control unit 50C includes a microcomputer including a CPU 51C having functions of a calculation unit and a control unit in a narrow sense, a RAM 52, a PROM 53C, and a timer 54 as a timing unit.

The PROM 53C functions as a first storage unit that stores a detection history of a jam of the transfer paper P that occurs between the relay conveyance unit 9C and the fixing unit 7. The PROM 53C also serves as a second storage unit that stores information on the transfer paper acquired by the transfer material information acquisition unit 47 in accordance with the changed outlet height of the relay conveyance unit 9C (conveyance belt 22). Function.
The PROM 53C stores necessary control programs and the like (see FIG. 14 described later), fixed data and the like in advance, and is configured to be programmable.

The CPU 51C is connected to two transfer paper detection sensors 75a and 75b, two jam detection sensors 77 and 78, and transfer material information acquisition means 47 via an input port, and via an output port and a motor driver. A cam motor 92 is connected. Further, the transfer material information acquisition means 47 is connected to the CPU 51C via an input / output port. Here, as the control components connected to the CPU 51C, only those closely related to the present invention are listed.
The CPU 51C of the control unit 50C instructs the cam motor 92 to output a predetermined number of drive pulses via the motor driver, thereby rotating the cam 91C, so that any of the four stages of cam surfaces described above can be driven. Is stopped at a predetermined rotational position.

The CPU 51C controls the cam motor 92 based on the detection results of the jam detection sensors 77 and 78 and the transfer paper detection sensors 75a and 75b, and information on the exit height of the relay conveyance unit 9C (conveyance belt 22) stored in the PROM 53C. The outlet height of the relay conveyance unit 9C is controlled.
That is, when a jam occurs, the CPU 51C, based on the detection information from the transfer paper detection sensors 75a and 75b, when the jam detection history is in the PROM 53C, the exit height of the relay conveyance unit 9C is increased in accordance with the warp amount. Thus, the cam motor 92 of the height changing means 90C is controlled. The CPU 51C functions as a control unit that controls the cam motor 92 of the height changing unit 90C so that the exit height of the relay conveyance unit 9C is lowered when the jam detection history is not in the PROM 53C.

  As described above, detection of whether or not the transfer paper P has normally passed through the fixing unit 7 (detection of jam) is performed by the jam detection sensors 77 and 78. The CPU 51C monitors the output signal of the jam detection sensor, and the jam detection sensors 77 and 78 do not detect the transfer paper P even after a predetermined time has elapsed after the transfer paper P is transferred to the secondary transfer nip N2. In this case, it is determined that a jam has occurred on the upstream side of the fixing unit 7. After detecting the occurrence of the jam, the CPU 51C follows the flow shown in FIG. 14 based on the presence / absence of the detection history of the transfer paper detection sensors 75a and 75b of the PROM 53C, and the behavior state / posture (back curl BC or face curl FC) of the transfer paper P. Or). In addition to this determination result, when there is a detection history of the transfer paper detection sensors 75a and 75b, the cam motor 92 is driven so that the exit height of the relay conveyance unit 9C increases in accordance with the amount of warpage. Control the outlet height and adjust it to the appropriate height.

FIG. 14 shows information (information on exit height corresponding to transfer paper brand) recorded in the PROM 53C, jam detection sensors 77 and 78, and transfer paper detection sensors 75a and 75b under the control of the CPU 51C of the control unit 50C. It is a figure which shows the flow which controls the exit height of the conveyance belt 22 based on the detection result.
The control flow of the second embodiment starts from step S21. The content of the control flow from step S21 to step S25 is the same as the content of the description from step S1 to step S5 of the control flow of the first embodiment shown in FIG. 7, and the PROM 53 is replaced with the PROM 53C, the height changing means 90 and the cam. Since 91 can be understood and implemented by replacing the height changing means 90C and the cam 91C with each other, description thereof will be omitted.

After the printing operation (sheet feeding operation) is started, it is checked whether or not a jam has occurred at the fixing nip entrance of the fixing unit 7. (Step S26). If the jam detection sensors 77 and 78 detect the occurrence of a jam, the transfer paper P is stopped (step S27).
Whether or not the leading edge of the transfer paper P is caught in the gap between the relay conveyance unit 9C and the fixing inlet guide plate 73 of the fixing unit 7 that is generated when the back curl BC occurs when the jam occurs in the above portion. Is detected by the transfer paper detection sensors 75a and 75b. At the same time, the size of the back curl BC is detected by the two transfer paper detection sensors 75a and 75b.

Next, the process proceeds to step S28, and it is checked whether or not the detection history of the transfer paper detection sensor 75a exists in the PROM 53C. When the detection history of the transfer paper detection sensor 75a is in the PROM 53C, the transfer paper P generates a small back curl BC as shown in FIG. 10, and the leading edge of the transfer paper P is located between the relay conveyance unit 9C and the fixing inlet guide plate 73. It can be seen that the transfer paper P is caught in the gap and the behavior of the transfer paper P is disturbed to cause a jam. Based on this, the cam surface of the cam 91C has a medium height of 91Ch1 and is raised to the position of the outlet height 22xH1 (see FIG. 12) of the relay conveyance unit 9C (conveyance belt 22) to increase the margin and prevent catching and jamming. (Step S29).
After the adjustment to the outlet height 22xH1, the brand of the transfer paper P corresponding to the changed outlet height 22xH1 is input to the CPU 51C of the control unit 50C, and the appropriate outlet height 22xH1 of the relay conveyance unit 9C (conveyance belt 22) is set. The brand of the transfer paper P is linked and stored in the PROM 53C (step S30).

On the other hand, in step S28, when the detection history of the transfer paper detection sensor 75a does not exist in the PROM 53C, the detection history of the transfer paper detection sensor 75b exists in the PROM 53C, and the transfer paper P causes a face curl FC as shown in FIG. Therefore, it is assumed that the leading edge of the transfer paper P is caught by the spur 74 and the behavior of the transfer paper P is disturbed and a jam occurs.
Therefore, when the detection history of the transfer paper detection sensor 75b is in the PROM 53C, the transfer paper P generates a larger back curl BC than shown in FIG. 10, and the leading end of the transfer paper P is connected to the relay conveyance unit 9C and the fixing inlet guide plate. It can be seen that the transfer paper P is caught in the gap 73 and the behavior of the transfer paper P is disturbed to cause a jam (step S31). Based on this, the cam surface of the cam 91C is raised to 91Ch2 and raised to the position of the outlet height 22xH2 (see FIG. 12) of the relay conveyance unit 9C (conveyance belt 22) to increase the margin and prevent catching and jamming. (Step S32).
After adjusting to the outlet height 22xH2, the brand of the transfer paper P corresponding to the changed outlet height 22xH2 is input to the CPU 51C of the control unit 50C, and the appropriate outlet height 22xH2 of the relay conveyance unit 9C (conveyance belt 22) is set. The brand of the transfer paper P is linked and stored in the PROM 53C (step S33).

In step S31, when the detection history of the transfer paper detection sensor 75b is not in the PROM 53C, the transfer paper P undergoes face curl FC as shown in FIG. It turns out that a jam has occurred. Based on this, the cam surface of the cam 91C is made low 91Cl and lowered to the position of the outlet height 22xL (see FIG. 12) of the relay conveyance unit 9C (conveyance belt 22) to increase the margin and prevent catching and jamming. (Step S34).
After the adjustment to the outlet height 22xL, the brand of the transfer paper P corresponding to the changed outlet height 22xL is input to the CPU 51C of the controller 50C, and the appropriate outlet height 22xL of the relay transport unit 9C and the brand of the transfer paper P Is stored in the PROM 53C (step S35).

After the information is stored in the PROM 53C in step S30, step S33, or step S35, when it is confirmed that the jam processing has been completed by the user or the like, the sheet passing operation is resumed. If no jam has occurred in step S26, the flow ends.
Note that if the printing does not end normally due to the occurrence of a jam, another image of the transfer sheet P may be passed again to print the image to be printed again.

  By the operations of step S30, step S33, and step S35 described above, when the transfer paper P of the same brand is passed next, the exit height of the relay conveyance unit 9C can be adjusted to an appropriate height before the paper. As a result, it is possible to prevent jamming and improve productivity.

  As described above, according to the second embodiment, the size of the back curl can be detected by the two transfer paper detection sensors 75a and 75b, and the relay conveyance unit (conveyance belt) according to the detected amount of back curl. The outlet height can be adjusted to an appropriate height. Needless to say, the same effects as those of the first embodiment can be obtained.

  The second embodiment can also be configured in the same manner as the first modification, the second modification, and the third modification of the first embodiment. Since these contents can be easily understood and implemented by those skilled in the art, description thereof will be omitted.

  In the second embodiment, the cam 91C capable of switching the outlet height of the relay conveyance unit 9C in four stages is used, but the present invention is not limited to this. That is, it is of course possible to use a cam that can switch the exit height of the relay conveyance unit (conveyance belt 22) more finely in multiple stages as necessary. Furthermore, the height changing means is not limited to the height changing means using a cam, and for example, a height changing means applying the displacement means disclosed in FIG. 9 of JP-A-2006-118688 may be used.

(Embodiment 3)
In the first embodiment shown in FIG. 1 to FIG. 7, the brand of the transfer paper P, which is a single parameter, and the appropriate outlet height of the relay conveyance unit 9 (conveyance belt 22) are stored in the PROM 53 and linked. . However, the amount of curl of the paper is greatly influenced by the humidity of the use environment, and even in the low humidity environment and the high humidity environment, the transfer paper P of the same brand changes, and accordingly, the appropriate exit height also changes.
Therefore, a third embodiment that can solve the above-described points to be improved of the first embodiment will be described with reference to FIGS. FIG. 15 is a cross-sectional view of a main part for explaining the height adjustment of the exit of the transport belt of the relay transport unit according to the third embodiment. FIG. 16 is a control block diagram illustrating a control configuration of the third embodiment. FIG. 17 is a flowchart illustrating the control operation of the third embodiment.

  The third embodiment is different from the image forming apparatus of the first embodiment shown in FIGS. 1 to 7 in that a relay conveyance unit 9D shown in FIG. 15 is used instead of the relay conveyance unit 9, as shown in FIG. In addition, the environmental humidity information acquisition means 48 for acquiring the humidity information of the usage environment is newly provided, and the point that the control unit 50D is used in place of the control unit 50 is mainly different. Except for these differences, the configuration and operation of the third embodiment are the same as those of the first embodiment.

The relay transport unit 9D is different from the relay transport unit 9 of FIGS. 2 and 3 in that a height changing unit 90D shown in FIG. 15 is used instead of the height changing unit 90. The height changing means 90D is different from the height changing means 90 in that the cam 91D is used instead of the cam 91 and the support plate 93 is removed.
That is, as shown in FIG. 15, the height changing means 90D has a cam 91D for changing the outlet height of the relay conveyance unit 9D and a cam motor 92 as a drive source connected to the cam shaft 91Da.

Similarly to the cam 91 of the first embodiment, the cams 91D are respectively disposed on both outer sides in the width direction Y with the conveyance belt 22 interposed therebetween. The pair of cams 91D is composed of a plate cam, and is connected by a cam shaft 91Da extending in the width direction Y so that a cam surface, which will be described later, of the outer periphery of the contour rotates in a state where the same cam surface is held in the same phase. . The cam 91 </ b> D is not limited to the configuration shown in FIG. 15, but may be a single cam provided outside one side in the width direction Y across the conveyance belt 22.
The cam 91D is a cam surface that can change the exit height of the relay conveyance unit 9D. The low, default, medium, and high heights of the first embodiment are changed from the original to a more appropriate exit height by control described later. It is an eccentric cam that can be switched in multiple stages. The position of the cam 91D in FIG. 15 is a state in which the default inner cam surface is in contact with the lower surface of the unit frame, whereby the outlet height of the relay conveyance unit 9D is set to the default: middle height position. It shows that there is.

  As shown in FIG. 15, when the cam motor 92 is driven to change the cam surface of the cam 91D from the middle rotational position corresponding to the default to the rotational position corresponding to low, the height of the outlet 22x of the conveyor belt 22 is lowered. As shown by the alternate long and short dash line, the exit height is 22 × L ′. When the cam motor 92 is further driven to bring the cam surface of the cam 91D to the rotational position corresponding to the height, the height of the outlet 22x of the conveyor belt 22 is increased to the position of the outlet height 22xH 'indicated by the broken line. Here, the outlet heights 22xL ′ and 22xH ′ of the third embodiment are described later in consideration of the environmental printing conditions (brand of transfer paper to be used, humidity of the usage environment) than the outlet heights 22xL and 22xH of the first embodiment. This indicates that the exit height is more accurate by the control.

Specifically, a humidity sensor 49 is used as the environmental humidity information acquisition unit 48. The humidity sensor 49 is installed in an arbitrary place of the apparatus main body 99 of the image forming apparatus 100 of FIG. 1, that is, an arbitrary place where the humidity of the use environment can be monitored.
The environmental humidity information acquisition unit 48 is not limited to the humidity sensor 49. For example, the control unit 50D of the image forming apparatus 100 according to the third embodiment includes acquiring and using environmental humidity information such as a possible place or region where the environmental humidity is the same from a weather information provider via the Internet. . The environmental humidity information acquisition unit 48 will be described below using a humidity sensor 49.

  The control unit 50D of the third embodiment is different from the control unit 50 of the first embodiment in that a CPU 51D is used instead of the CPU 51, and a PROM 53D is used instead of the PROM 53. In FIG. 16, the control unit 50D functions as a broadly defined control unit that controls the image forming operation and the operation of the height changing unit 90D. The control unit 50D includes a microcomputer including a CPU 51D having functions of a calculation unit and a control unit in a narrow sense, a RAM 52, a PROM 53D, and a timer 54 as a timing unit.

The PROM 53D functions as a first storage unit that stores a detection history of a jam of the transfer paper P that occurs between the relay conveyance unit 9D and the fixing unit 7. Further, the PROM 53D corresponds to the changed exit height of the relay conveyance unit 9D (conveyance belt 22), the transfer paper information acquired by the transfer material information acquisition unit 47, and the humidity of the environmental humidity information acquisition unit 48. It also functions as third storage means for storing the humidity information of the usage environment detected by the sensor 49.
The PROM 53D stores necessary control programs (see FIG. 17 described later), fixed data, and the like in advance and is configured to be programmable. The PROM 53D may be a nonvolatile memory as described above.

For example, when the environmental humidity is classified into three regions, that is, a low humidity environment of 29% or less, a standard environment of 30 to 70%, and a high humidity environment of 71% or more, in one brand of the transfer paper P, the low humidity environment, the standard Appropriate exit height information can be stored in the PROM 53D corresponding to the environment and the high humidity environment. In addition, all the said humidity is relative humidity (RH).
In the history stored in the PROM 53D, when the brands of the transfer paper P match but the humidity environment is different, the history of different humidity environments may be used. At that time, when there are a plurality of different humidity environment histories, the history in the standard environment is used with priority.

  In the third embodiment, the environmental humidity is classified as low humidity environment of 29% or less, 30 to 70% as standard environment, and 71% or more as high humidity environment. However, the present invention is not limited to this. Is possible.

The input / output configuration of the CPU 51D of the control unit 50D is different from that of the first embodiment only in that the environmental humidity information acquisition unit 48 (humidity sensor 49) is connected via the input port.
As the cam motor 92, a stepping motor is used. The CPU 51D commands the cam motor 92 to output a predetermined number of drive pulses via the motor driver, thereby rotating the cam 91D and driving any one of the above-described three stages of the cam surface to a predetermined level. Stop at the rotational position.

The CPU 51D detects the cam motor 92 based on the detection results of the jam detection sensors 77 and 78, the transfer paper detection sensor 75, and the humidity sensor 49, and information on the exit height of the relay conveyance unit 9D (conveyance belt 22) stored in the PROM 53D. And the exit height of the relay conveyance unit 9D is controlled.
That is, when a jam occurs, the CPU 51D changes the height based on the detection information from the transfer paper detection sensor 75 so that when the jam detection history is in the PROM 53D, the exit height of the relay conveyance unit 9D is increased. The cam motor 92 of the means 90 is controlled. The CPU 51D functions as a control unit that controls the cam motor 92 of the height changing unit 90 so that the exit height of the relay conveyance unit 9D is lowered when the jam detection history is not in the PROM 53D.

  As described above, detection of whether or not the transfer paper P has normally passed through the fixing unit 7 (detection of jam) is performed by the jam detection sensors 77 and 78. The CPU 51D monitors the output signal of the jam detection sensor, and the jam detection sensors 77 and 78 do not detect the transfer paper P even after a predetermined time has elapsed after the transfer paper P is transferred to the secondary transfer nip N2. In this case, it is determined that a jam has occurred on the upstream side of the fixing unit 7. After detecting the occurrence of a jam, the CPU 51D follows the flow shown in FIG. 17 based on the presence / absence of the detection history of the transfer paper detection sensor 75 of the PROM 53D, and the behavior state / posture (back curl BC or face curl FC) of the transfer paper P. Judging. Based on the determination result, the cam motor 92 is driven to control the outlet height of the relay conveyance unit 9D.

FIG. 17 shows information recorded on the PROM 53D (information on exit height corresponding to transfer paper brand and humidity information), jam detection sensors 77 and 78, and transfer paper detection sensor under the control of the CPU 51D of the control unit 50D. It is a figure which shows the flow which controls the exit height of the conveyance belt 22 based on the detection result of 75 and the humidity sensor 49. FIG.
The control flow of the third embodiment starts from step S41 shown in FIG. First, in step S41, transfer material information relating to the brand of the transfer paper to be passed is acquired from the transfer material information set by the transfer material information acquisition means 47. Next, the process proceeds to step S42, where the humidity information of the usage environment detected and acquired by the humidity sensor 49 is acquired (may be acquired by the environmental humidity information acquisition means 48 as described above). In addition, what replaced operation | movement of step S41 and step S42, ie, the operation | movement which followed, may be sufficient.
Next, it is determined and checked whether or not the exit height of the relay transport unit 9D (transport belt 22) corresponding to the acquired transfer paper brand and the acquired humidity information is stored in the PROM 53D (step S43). If the exit height corresponding to the brand of transfer paper and the humidity information is not stored in the PROM 53D, the process proceeds to step S44. In step S44, the cam 91D is rotationally driven by the cam motor 92 of the height changing means 90D, and the exit height is set to the default height (positions of the relay conveyance unit 9D and the conveyance belt 22 shown by solid lines in FIG. 15). Set.
On the other hand, in step S43, when the exit height of the relay transport unit 9D (transport belt 22) corresponding to the acquired transfer paper brand and the acquired humidity information is stored in the PROM 53D, the process proceeds to step S45 and the height is changed. The outlet height is set to the stored height by means 90D.

If the exit height is set, the printing operation (sheet passing operation) is started (step S46). After the printing operation (sheet feeding operation) is started, it is checked whether or not a jam has occurred at the fixing nip entrance of the fixing unit 7. (Step S47). If the jam detection sensors 77 and 78 detect the occurrence of the jam, the transfer paper P is stopped (step S48).
Whether or not the leading edge of the transfer paper P is caught in the gap between the relay conveyance unit 9D and the fixing entrance guide plate 73 of the fixing unit 7 that occurs when the back curl BC occurs when the jam occurs in the above portion. Is detected by the transfer paper detection sensor 75.

In step S49, it is checked whether or not the detection history of the transfer paper detection sensor 75 exists in the PROM 53D. When the detection history of the transfer paper detection sensor 75 is in the PROM 53D, the transfer paper P undergoes back curl BC as shown in FIG. 15, and the leading edge of the transfer paper P is in the gap between the relay conveyance unit 9D and the fixing inlet guide plate 73. It can be seen that the behavior of the catching transfer paper P is disturbed and a jam has occurred. Based on this, the cam surface of the cam 91D is raised and raised to the position of the outlet height 22xH ′ (see FIG. 15) of the relay conveyance unit 9D (conveyance belt 22) to increase the margin and prevent catching and jamming. (Step S50).
After adjusting to the outlet height 22xH ′, the brand and humidity information of the transfer paper P corresponding to the changed outlet height 22xH are input to the CPU 51D, and an appropriate outlet height 22xH of the relay conveyance unit 9D (conveyor belt 22) is input. ', The brand of the transfer paper P, and the humidity information are linked and stored in the PROM 53D (step S51).

On the other hand, in step S49, when the detection history of the transfer paper detection sensor 75 is not in the PROM 53D, the transfer paper P is face curled FC (see FIG. 2), the leading edge of the transfer paper P is caught by the spur 74, and the transfer paper P It can be seen that the behavior is disturbed and a jam has occurred. Based on this, the cam surface of the cam 91D is lowered and lowered to the position of the outlet height 22xL ′ (see FIG. 15) of the relay conveyance unit 9D (conveyance belt 22) to increase the margin and prevent catching and jamming. (Step S52).
After the adjustment to the outlet height 22xL ′, the brand of the transfer paper P corresponding to the changed outlet height 22xL ′ and the humidity information are input to the CPU 51D, and the appropriate outlet height 22xL ′ of the relay transport unit 9D is transferred. The brand of the paper P and the humidity information are linked and stored in the PROM 53D (step S53).

After the information is stored in the PROM 53D in step S51 or step S53, when the end of the jam processing by the user or the like is confirmed, the sheet passing operation is resumed. If no jam has occurred in step S47, the flow ends.
Note that if the printing does not end normally due to the occurrence of a jam, another image of the transfer sheet P may be passed again to print the image to be printed again.

  When the same brand transfer paper P is passed next by the operations of step S51 and step S53 described above, and when the humidity of the use environment falls into any one of the above-described area classifications, relaying is performed. The exit height of the transport unit 9D can be adjusted to an appropriate height before feeding. As a result, it is possible to prevent jamming and improve productivity.

  As described above, according to the third embodiment, in addition to the brand of the transfer paper P and the appropriate outlet height of the relay transport unit 9D, the humidity information of the use environment is also stored in the PROM 53D, and the brand of the transfer paper P is stored. By connecting the two parameters of the humidity of the environment and the appropriate outlet height, a more accurate outlet height can be set. Needless to say, the same basic effects as those of the first embodiment can be obtained.

  The third embodiment can also be configured in the same manner as the first modification, the second modification, and the third modification of the first embodiment. Since these contents can be easily understood and implemented by those skilled in the art, description thereof will be omitted.

(Embodiment 4)
In the second embodiment shown in FIGS. 10 to 14, the brand of the transfer paper P, which is a single parameter, and the appropriate outlet height of the relay conveyance unit 9 </ b> C (conveyance belt 22) are stored in the PROM 53 </ b> C and linked. . However, the amount of curl of the paper is greatly influenced by the humidity of the use environment, and even in the low humidity environment and the high humidity environment, the transfer paper P of the same brand changes, and accordingly, the appropriate exit height also changes.
Therefore, a fourth embodiment that can solve the above-described points to be improved of the second embodiment will be described with reference to FIGS. FIG. 18 is a cross-sectional view of a main part for explaining the height adjustment of the exit of the transport belt of the relay transport unit according to the fourth embodiment. FIG. 19 is a control block diagram illustrating a control configuration of the fourth embodiment. FIG. 20 is a flowchart illustrating a control operation according to the fourth embodiment.

  As compared with the image forming apparatus of the second embodiment shown in FIGS. 10 to 14, the fourth embodiment uses a relay conveyance unit 9 </ b> E shown in FIG. 18 instead of the relay conveyance unit 9 </ b> C, as shown in FIG. 19. In addition, the environmental humidity information acquisition means 48 for acquiring the humidity information of the usage environment is newly provided, and the control unit 50E is used instead of the control unit 50C. Except for these differences, the configuration and operation of the fourth embodiment are the same as those of the second embodiment.

The relay transport unit 9E is different from the relay transport unit 9C of FIGS. 10 and 12 in that a height changing unit 90E shown in FIG. 18 is used instead of the height changing unit 90C. The height changing unit 90E is different from the height changing unit 90C in that a cam 91E is used instead of the cam 91C.
That is, as shown in FIG. 18, the height changing unit 90E includes a cam 91E for changing the outlet height of the relay conveyance unit 9E, and a cam motor 92 as a drive source connected to the cam shaft 91Ea.

Similarly to the cam 91 </ b> C of the second embodiment, the cams 91 </ b> E are respectively disposed on both outer sides in the width direction Y across the conveyance belt 22. The pair of cams 91E are plate cams, and are connected by a cam shaft 91Ea extending in the width direction Y so that a cam surface, which will be described later, on the outer periphery of the contour rotates in a state where the same cam surface is held in the same phase. . The cam 91E is not limited to the configuration shown in FIG. 18, and may be a single cam 91E provided on one outer side in the width direction Y across the conveyance belt 22.
The cam 91E is a cam surface that can change the exit height of the relay conveyance unit 9E. The low, default medium, medium and high heights of the second embodiment are used as the cam surface, and the exit height is more appropriate by the control described later. It is an eccentric cam that can be switched in multiple stages so that it can be changed. The position of the cam 91E in FIG. 18 is a state in which the default inner cam surface is in contact with the lower surface of the unit frame, whereby the outlet height of the relay conveyance unit 9E is set to the default: middle height position. It shows that there is.

  As shown in FIG. 18, when the cam motor 92 is driven to change the cam surface of the cam 91E from the middle rotational position corresponding to the default to the rotational position corresponding to the low, the height of the outlet 22x of the conveyor belt 22 is lowered. As shown by the alternate long and short dash line, the exit height is 22 × L ′. When the cam motor 92 is further driven to bring the cam surface of the cam 91E to the rotational position corresponding to the height, the height of the outlet 22x of the conveyor belt 22 is increased to the position of the outlet height 22xH2 'indicated by the broken line. When the cam motor 92 is further driven to bring the cam surface of the cam 91E to the rotational position corresponding to the middle height, the height of the outlet 22x of the conveyor belt 22 is adjusted to the position of the outlet height 22xH1 ′ indicated by the two-dot broken line. Become. Here, the outlet height 22xL ′, the outlet heights 22xH2 ′, and 22xH1 ′ of the fourth embodiment are more environmental printing conditions than the outlet heights 22xL, 22xH2, and 22xH1 of the second embodiment. This means that the outlet height is more accurate by the control described below in consideration of the humidity of the environment.

The control configuration of the fourth embodiment will be described with reference to FIG. FIG. 19 is a control block diagram illustrating a control configuration of the fourth embodiment.
The control unit 50E of the fourth embodiment is mainly different from the control unit 50C of the second embodiment in that a CPU 51E is used instead of the CPU 51C and a PROM 53E is used instead of the PROM 53C. In FIG. 19, the control unit 50E functions as a broadly defined control unit that controls the image forming operation and the operation of the height changing unit 90E. The control unit 50E includes a microcomputer including a CPU 51E having functions of a calculation unit and a control unit in a narrow sense, a RAM 52, a PROM 53E, and a timer 54 as a timing unit.

The PROM 53E functions as a first storage unit that stores a detection history of a jam of the transfer paper P that occurs between the relay conveyance unit 9C and the fixing unit 7. In addition, the PROM 53E corresponds to the changed exit height of the relay conveyance unit 9E (conveyance belt 22), the transfer sheet information acquired by the transfer material information acquisition unit 47, and the humidity of the environmental humidity information acquisition unit 48. It also functions as third storage means for storing the humidity information of the usage environment detected by the sensor 49.
The PROM 53E stores necessary control programs (see FIG. 20 described later), fixed data, and the like in advance and is configured to be programmable. The PROM 53E may be a nonvolatile memory as described above.

  The number of environmental humidity categories and threshold values, the history of humidity environment, and the like stored in the PROM 53E are the same as those described in the third embodiment.

The input / output configuration of the CPU 51E of the control unit 50E is different from that of the second embodiment only in that the environmental humidity information acquisition unit 48 (humidity sensor 49) is connected via the input port.
As the cam motor 92, a stepping motor is used. The CPU 51E instructs the cam motor 92 to output a predetermined number of drive pulses via the motor driver, thereby rotating the cam 91E and causing any one of the above-described four stages of cam surfaces to be predetermined. Stop at the rotational position.

The CPU 51E is based on the detection results of the jam detection sensors 77 and 78, the transfer paper detection sensors 75a and 75b, and the humidity sensor 49, and information on the exit height of the relay conveyance unit 9E (conveyance belt 22) stored in the PROM 53E. The cam motor 92 is controlled to control the outlet height of the relay transport unit 9E.
That is, when a jam occurs, the CPU 51E determines that the exit height of the relay conveyance unit 9E is high according to the amount of warp when the jam detection history is in the PROM 53E based on the detection information from the transfer paper detection sensors 75a and 75b. Thus, the cam motor 92 of the height changing means 90E is controlled. The CPU 51E functions as a control unit that controls the cam motor 92 of the height changing unit 90E so that the exit height of the relay conveyance unit 9E is lowered when the jam detection history is not in the PROM 53E.

  As described above, detection of whether or not the transfer paper P has normally passed through the fixing unit 7 (detection of jam) is performed by the jam detection sensors 77 and 78. The CPU 51E monitors the output signal of the jam detection sensor, and the jam detection sensors 77 and 78 do not detect the transfer paper P even if a predetermined time elapses after the transfer paper P is transferred at the secondary transfer nip N2. In this case, it is determined that a jam has occurred on the upstream side of the fixing unit 7. After detecting the occurrence of a jam, the CPU 51E follows the flow shown in FIG. 20 based on the presence / absence of the detection history of the transfer paper detection sensors 75a and 75b of the PROM 53E (the back curl BC or the face curl FC). Or). In addition to this determination result, when there is a detection history of the transfer paper detection sensors 75a and 75b, the cam motor 92 is driven so that the exit height of the relay transport unit 9E increases in accordance with the amount of warpage, and the relay transport unit 9E Control the outlet height and adjust it to the appropriate height.

FIG. 20 shows information recorded in the PROM 53E (exit height information corresponding to transfer paper brand and humidity information), jam detection sensors 77 and 78, and transfer paper detection sensor under the control of the CPU 51E of the control unit 50E. It is a figure which shows the flow which controls the exit height of the conveyance belt 22 based on the detection result of 75a, 75b and the humidity sensor 49. FIG.
The control flow of the fourth embodiment starts from step S61 in FIG. First, in step S61, transfer material information relating to the brand of the transfer paper to be passed is acquired from the transfer material information set by the transfer material information acquisition means 47. Next, the process proceeds to step S62, where the humidity information of the usage environment detected and acquired by the humidity sensor 49 is acquired (may be acquired by the environmental humidity information acquisition means 48 as described above). In addition, what replaced operation | movement of step S61 and step S62, ie, the operation | movement which followed, may be sufficient.
Next, it is determined and checked whether or not the exit height of the relay transport unit 9E (transport belt 22) corresponding to the acquired transfer paper brand and the acquired humidity information is stored in the PROM 53E (step S63). If the exit height corresponding to the brand of transfer paper and the humidity information is not stored in the PROM 53E, the process proceeds to step S64. In step S64, the cam 91E is rotationally driven by the cam motor 92 of the height changing means 90E, and the exit height is set to the default height (positions of the relay conveyance unit 9E and the conveyance belt 22 indicated by solid lines in FIG. 18). Set.
On the other hand, if the exit height of the relay transport unit 9E (transport belt 22) corresponding to the acquired transfer paper brand and the acquired humidity information is stored in the PROM 53E in step S63, the process proceeds to step S65 and the height is changed. The outlet height is set to a stored height by means 90E.

If the exit height is set, the printing operation (paper feeding operation) is started (step S66). After the printing operation (sheet feeding operation) is started, it is checked whether or not a jam has occurred at the fixing nip entrance of the fixing unit 7. (Step S67). If the jam detection sensors 77 and 78 detect the occurrence of a jam, the transfer paper P is stopped (step S68).
Whether or not the leading edge of the transfer paper P is caught in the gap between the relay conveyance unit 9E and the fixing inlet guide plate 73 of the fixing unit 7 that is generated when the back curl BC occurs when the jam occurs in the above portion. Is detected by the transfer paper detection sensors 75a and 75b. At the same time, the size of the back curl BC is detected by the two transfer paper detection sensors 75a and 75b.

In step S69, it is checked whether or not the detection history of the transfer paper detection sensor 75a exists in the PROM 53E. When the detection history of the transfer paper detection sensor 75a is in the PROM 53E, the transfer paper P generates a small back curl BC as shown in FIG. 10, and the leading edge of the transfer paper P is connected to the relay conveyance unit 9E and the fixing inlet guide plate. It can be seen that the jam of the transfer paper P is disturbed by the gap 73 and the behavior of the transfer paper P is disturbed. Based on this, the cam surface of the cam 91E is set to a rotational position corresponding to the middle height, and the margin is increased by raising the outlet height 22xH1 ′ (see FIG. 18) of the relay conveyance unit 9E (conveyance belt 22). Catch and jam are prevented (step S70).
After adjusting to the outlet height 22xH1 ′, the brand and humidity information of the transfer paper P corresponding to the changed outlet height 22xH1 ′ are input to the CPU 51E of the control unit 50E, and the relay conveying unit 9E (conveying belt 22) is appropriately selected. The exit height 22xH1 ′, the brand of the transfer paper P, and the humidity information are linked and stored in the PROM 53E (step S71).

On the other hand, in step S69, when the detection history of the transfer paper detection sensor 75a is not in the PROM 53E, the detection history of the transfer paper detection sensor 75b is in the PROM 53E, and the face curl FC as shown in FIG. It is assumed that the leading edge of the transfer paper P is caught by the spur 74, the behavior of the transfer paper P is disturbed, and a jam occurs.
Therefore, when the detection history of the transfer paper detection sensor 75b is in the PROM 53E, the transfer paper P generates a larger back curl BC than shown by borrowing FIG. 10, and the leading edge of the transfer paper P is connected to the relay conveyance unit 9E and the fixing entrance. It can be seen that the jam of the transfer sheet P is caught by being caught in the gap between the guide plates 73 (step S72). Based on this, the cam surface of the cam 91E is set to a rotational position corresponding to the height, and the margin is increased by raising it to the position of the outlet height 22xH2 ′ (see FIG. 18) of the relay conveyance unit 9E (conveyance belt 22). Catch and jam are prevented (step S73).
After adjusting to the outlet height 22xH2 ′, the brand and humidity information of the transfer paper P corresponding to the changed outlet height 22xH2 ′ are input to the CPU 51E of the control unit 50E, and the relay conveying unit 9E (conveying belt 22) is appropriately selected. The exit height 22xH2 ′, the brand of the transfer paper P, and the humidity information are linked and stored in the PROM 53E (step S74).

In step S72, when there is no detection history of the transfer paper detection sensor 75b in the PROM 53E, the transfer paper P is face curled FC as shown in FIG. It can be seen that jamming has occurred. Based on this, the cam surface of the cam 91E is set to a rotational position corresponding to low, and the margin is increased by lowering to the position of the outlet height 22xL ′ (see FIG. 18) of the relay conveyance unit 9E (conveyance belt 22). Locking and jamming are prevented (step S75).
After adjusting to the outlet height 22xL ′, the brand and humidity information of the transfer paper P corresponding to the changed outlet height 22xL ′ are input to the CPU 51E of the control unit 50E, and the appropriate outlet height 22xL of the relay conveyance unit 9E is input. ', The brand of the transfer paper P and the humidity information are linked and stored in the PROM 53E (step S76).

After the information is stored in the PROM 53E in step S71, step S74, or step S76, when it is confirmed that the jam processing has been completed by the user or the like, the sheet passing operation is resumed. If no jam has occurred in step S67, the flow ends.
Note that if the printing does not end normally due to the occurrence of a jam, another image of the transfer sheet P may be passed again to print the image to be printed again.

  By the operations of Step S71, Step S74, and Step S76 described above, the next time the transfer paper P of the same brand is passed, and the humidity of the use environment falls into any one of the above-described area classifications. At this time, the height of the exit of the relay conveyance unit 9E can be adjusted to an appropriate height before passing the paper. As a result, it is possible to prevent jamming and improve productivity.

  As described above, according to the fourth embodiment, in addition to the brand of the transfer paper P and the appropriate outlet height of the relay transport unit 9E, the humidity information of the use environment is also stored in the PROM 53E, and the brand of the transfer paper P is stored. By connecting the two parameters of the humidity of the environment and the appropriate outlet height, a more accurate outlet height can be set. Needless to say, the same effects as those of the first and second embodiments can be obtained.

  The fourth embodiment can also be configured in the same manner as the first modification, the second modification, and the third modification of the first embodiment. Since these contents can be easily understood and implemented by those skilled in the art, description thereof will be omitted.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the specific embodiments, and the present invention described in the claims is not specifically limited by the above description. Various modifications and changes are possible within the scope of the above. For example, the technical matters described in the above embodiments may be appropriately combined.

  For example, the transfer material detection means of the present invention is not limited to the configuration in which the behavior state of the transfer material including the back curl is detected as in the first embodiment, but the behavior state of the transfer material including the face curl is not limited to the configuration. The structure arrange | positioned in the position to detect may be sufficient. That is, the transfer material detection means includes a back curl in which the front end of the transfer material is warped toward the first surface (the back surface of the transfer material), and the front end of the transfer material is the second surface (the front surface of the transfer material). Alternatively, a configuration may be adopted in which the position of one of the transfer materials of the face curl that warps to the side can be detected.

  The image forming apparatus according to the present invention is also applicable to a tandem type intermediate transfer type image forming apparatus as in the first embodiment or a tandem type direct transfer type image forming apparatus. Further, the present invention can be applied to or applied mutatis mutandis to an image forming apparatus including a transfer unit including a single latent image carrier and a single transfer body.

  The effects appropriately described in the embodiments of the present invention are merely a list of the most preferable effects resulting from the present invention, and the effects of the present invention are limited to those described in the embodiments of the present invention. It is not a thing.

DESCRIPTION OF SYMBOLS 1 Paper feeder 2 Transfer unit 3 Intermediate transfer belt 4 Image forming unit 5 Optical scanning device 6 Transfer conveyance device 7 Fixing unit 9, 9A, 9B, 9C, 9D, 9E Relay conveyance unit 10 Paper feed path 12 Registration roller pair 20 Drive Roller 21 Followed roller 22 Conveying belt (an example of a conveying member)
22x Conveyor belt outlet 23 Unit frame 31 Driving roller 35 Repulsive roller 40 Photoconductor (an example of an image carrier)
41 Charging device 42 Developing device 43 Cleaning device 48 Environmental humidity information acquisition means 49 Humidity sensor (an example of environmental humidity information acquisition means)
50, 50C, 50D, 50E control unit (an example of control means in a broad sense)
51, 51C, 51D, 51E CPU (an example of control means in a narrow sense)
53, 53C PROM (an example of first and second storage means)
53D, 53E PROM (an example of first and third storage means)
71 Heating roller 72 Pressure roller 73, 73B Fixing entrance guide plate (an example of guide member)
73x Entrance 75 of fixing entrance guide plate Transfer paper detection sensor (an example of transfer material detection means)
75a, 75b Transfer paper detection sensor (an example of transfer material detection means)
77, 78 Jam detection sensor (an example of jam detection means)
90, 90A, 90C, 90D, 90E Height changing means (an example of position changing means)
91, 91C, 91D, 91E Cam 92 Cam motor 99 Apparatus body (an example of an image forming apparatus body)
100 Image forming apparatus BC Back curl FC Face curl NC No curl N Fixing nip N1 Primary transfer nip N2 Secondary transfer nip P Transfer paper (an example of a transfer material)
X Transfer material conveyance direction Y Width direction Z Vertical direction / Height direction

JP 2001-240268 A JP 2010-085976 A

Claims (12)

A transfer unit for transferring a toner image on the image carrier to a transfer material;
A fixing unit for fixing a toner image on a transfer material;
A relay conveyance unit having a conveyance member for conveying a transfer material between the transfer unit and the fixing unit;
Position changing means for changing the position of the downstream end of the transfer member in the transfer material conveyance direction;
A transfer material detecting means for detecting that the tip of the transfer material that has exited from the outlet of the conveying member warps toward the first surface;
When a jam occurs between the transfer unit and the fixing unit, it is detected that the front end of the transfer material warps toward the first surface based on the detection result from the transfer material detection unit. If the position of the exit is moved in the direction from the first surface to the second surface of the transfer material, and the tip of the transfer material is not detected to warp toward the first surface, the exit Control means for controlling the position changing means so as to move the position of the transfer material in a direction from the second surface of the transfer material toward the first surface;
An image forming apparatus comprising: The image forming apparatus according to claim 1.
A plurality of the transfer material detection means are arranged along the warp direction so that the amount of warpage to the first surface side of the front end of the transfer material that has come out of the exit of the conveying member can be detected stepwise.
The control means determines the position of the outlet when the tip of the transfer material is warped toward the first surface based on detection results from the plurality of transfer material detection means. An image forming apparatus, wherein the position changing unit is controlled to move in a direction from one surface to a second surface in accordance with the amount of warpage. The image forming apparatus according to claim 1 or 2,
An image forming apparatus comprising: at least one jam detecting unit that detects the jam on an upstream side and a downstream side in the transfer material conveyance direction of the fixing unit. The image forming apparatus according to any one of claims 1 to 3,
An image forming apparatus comprising: a first storage unit configured to store a detection history of a jam of a transfer material generated between the relay conveyance unit and the fixing unit. The image forming apparatus according to any one of claims 1 to 4,
Transfer material information acquisition means for acquiring transfer material information;
Second storage means for storing information on the transfer material acquired by the transfer material information acquisition means in correspondence with the changed position of the outlet;
An image forming apparatus comprising: The image forming apparatus according to any one of claims 1 to 4,
Transfer material information acquisition means for acquiring transfer material information;
Environmental humidity information acquisition means for acquiring humidity information of the usage environment;
Corresponding to the changed position of the outlet, information on the transfer material acquired by the transfer material information acquisition unit and information on the use environment humidity acquired by the environmental humidity information acquisition unit are stored. Three storage means;
An image forming apparatus comprising: In the image forming apparatus according to any one of claims 1 to 6,
A guide member for guiding a transfer material conveyed by the conveyance member to a fixing nip of the fixing unit;
The relay conveyance unit is configured to be replaceable with respect to the image forming apparatus main body,
The image forming apparatus, wherein the transfer material detecting means or the plurality of transfer material detecting means is installed on the guide member. In the image forming apparatus according to any one of claims 1 to 6,
A guide member for guiding a transfer material conveyed by the conveyance member to a fixing nip of the fixing unit;
The guide member is configured to be replaceable with respect to the image forming apparatus main body,
The image forming apparatus, wherein the transfer material detection unit or the plurality of transfer material detection units is installed in the relay conveyance unit. In the image forming apparatus according to any one of claims 1 to 6,
A guide member for guiding a transfer material conveyed by the conveyance member to a fixing nip of the fixing unit;
The guide member and the relay conveyance unit are configured to be replaceable with respect to the image forming apparatus main body,
The image forming apparatus, wherein the transfer material detection unit or the plurality of transfer material detection units is installed in a longer exchange cycle of the guide member and the relay conveyance unit. The image forming apparatus according to any one of claims 1 to 9,
The relay transport unit is configured to be swingable with an end portion on the transfer unit side in the transfer material transport direction or a vicinity of the end portion as a fulcrum, and the position changing unit includes the relay transport unit. An image forming apparatus characterized in that the position of the outlet is changed in accordance with rocking. The image forming apparatus according to any one of claims 1 to 9,
The relay transport unit is configured such that the entire relay transport unit can be displaced in the vertical direction so that the outlet of the transport member and the inlet of the upstream end of the transport member in the transfer material transport direction are substantially parallel to each other. In addition, the position changing means changes the position of the outlet as the relay transport unit is displaced in the vertical direction. The image forming apparatus according to claim 1,
The image forming apparatus, wherein the conveying member is a conveying belt.

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