JP2008185789A - Transfer material conveyance method, transfer material conveyance apparatus, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transfer material conveyance method and a transfer material conveyance apparatus for stably feeding transfer material after transfer into a fixing device regardless of in particular the curling direction of transfer material. <P>SOLUTION: In the transfer material conveyance method for the image forming apparatus in which the transfer material separated from an image carrier is conveyed toward a fixing means while it is sucked onto a conveying belt as shown in Fig.3, a control means controls to convey the transfer material while the center part of the conveying belt B is displaced upward or downward from a reference position in accordance with the curling state of the transfer material P by detecting the curling state thereof by detection means S5 and S10. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a transfer material conveyance method, a transfer material conveyance device, and an image forming apparatus including the transfer material conveyance device in an image forming apparatus such as a copying machine or a printer.

  A manuscript or an electrostatic latent image (electrostatic charge pattern) corresponding to image data is produced on an image carrier comprising a photosensitive drum or the like, then the latent image is converted into a toner image, and then the toner An image forming apparatus configured to transfer an image onto a transfer material and perform a fixing process is well known.

  In such an image forming apparatus, a conveying belt is generally used as a transfer material conveying unit that conveys a transferred transfer material separated from an image carrier to a fixing device.

  There are various configurations of the transfer material conveyance device including the conveyance belt, but basically, the transfer material conveyance device includes a conveyance belt having many small holes and suction means for adsorbing the transfer material onto the conveyance belt.

  The reason for this is to eliminate the problem that the separated transfer material moves on the conveying belt, and always feeds the transfer material to the fixing device in a stable state.

  However, even if the position on the conveying belt is maintained, the transfer material has a problem that the front end and / or the rear end of the transfer material is easily curled in the case of double-sided image formation.

  For example, if the leading end in the transport direction of a small size transfer material is curled with thick paper, the leading end may not be attracted to the transport belt, and as a result, the entrance of the fixing device There is a risk that the transfer material will be clogged (jammed) at the part.

  The following proposal has been made as a measure for such a curled transfer material.

  That is, a restricting means is provided at a position before the entrance of the fixing device, and when the sheet detecting means for detecting the leading edge and the trailing edge of the transfer material after the transfer detects the leading edge or the trailing edge of the transfer material, This is a configuration in which the restricting means is moved to the restricting position to prevent the transfer material from rising.

Alternatively, when the curling of the sheet after the transfer is detected by the detection means, the configuration is such that the difference between the entrance of the fixing device and the conveyance surface of the conveyance belt on the fixing device side is adjusted based on the detection result ( Patent Document 1).
JP-A-6-127742

  However, in the first proposal disclosed in Patent Document 1, for example, there is a risk that the transferred toner image may be disturbed because the regulating means repels the image surface side tip of the transfer material.

  In the second proposal, it is considered that the suction efficiency of the suction fan is low. Furthermore, if the curl direction of the transfer material is a concave curl, it is considered that the effect is equivalent. In the case of, there is a problem that can not be handled.

  The present invention has been made in view of the above-mentioned problems, and the main object is to transfer the transferred transfer material into the fixing device stably regardless of the curl direction of the transfer material. It is an object to provide a transfer material conveyance method and a transfer material conveyance device.

  The object of the present invention can be achieved by the following constitutional requirements.

(1)
In the transfer material transport method in the image forming apparatus that transports the transfer material separated from the image carrier toward the fixing unit while adsorbing the transfer material to the transport belt,
The curling state of the transfer material is detected by the detecting means, and the control means is controlled so as to convey the transfer material in a state where the central portion of the conveying belt is displaced upward or downward from the reference position according to the curled state. A transfer material conveying method characterized by:

(2)
In the transfer material conveying apparatus configured to convey the transfer material separated from the image carrier toward the fixing unit while adsorbing the transfer material to the conveyance belt,
When viewed in the transfer material conveyance direction, the conveyance belt is constituted by a plurality of stations, and only two conveyance belt suspension rollers positioned at both ends thereof are fixed in position, and the conveyance belt suspension provided between the position fixing rollers is fixed. The common roller can be displaced, and
When the curling state of the transfer material is detected by the detecting means, and the curled state is a convex curl, the common roller provided so as to be movable up and down is displaced upward via the position displacing means, and When the curled state is a concave curl, the transfer material conveying device is configured to be controlled by the control means so that the common roller is displaced downward via the position displacement means.

(3)
In the transfer material conveying apparatus configured to convey the transfer material separated from the image carrier toward the fixing unit while adsorbing the transfer material to the conveyance belt,
When viewed in the transfer material conveyance direction, the conveyance belt is configured in two, and one end side of each conveyance belt is provided on the position fixing rollers provided at both ends, and a common roller provided between the position fixing rollers. Suspend the other end of each conveyor belt,
When the curling state of the transfer material is detected by the detecting means, and the curled state is a convex curl, the common roller provided so as to be movable up and down is displaced upward via the position displacing means, and When the curled state is a concave curl, the transfer material conveying device is configured to be controlled by the control means so that the common roller is displaced downward via the position displacement means.

(4)
In the transfer material conveying apparatus configured to convey the transfer material separated from the image carrier toward the fixing unit while adsorbing the transfer material to the conveyance belt,
As seen in the transfer material conveyance direction, the conveyance belt is configured in triplicate,
One end side of the first and second conveying belts positioned on both end sides is suspended from the position fixing rollers provided at both ends, and the side closer to the two common rollers provided between the position fixing rollers Suspend the other end side of each of the first and second transport belts to a common roller located at a position, and further suspend a third transport belt to the two common rollers,
When the curling state of the transfer material is detected by the detecting means, and the curled state is a convex curl, the common roller provided so as to be movable up and down is displaced upward via the position displacing means, and When the curled state is a concave curl, the transfer material conveying device is configured to be controlled by the control means so that the common roller is displaced downward via the position displacement means.

(5)
An image forming apparatus comprising the transfer material conveying device according to any one of (2) to (4).

  In the inventions of (1) to (4), the position movement direction of the central portion (intermediate portion) of the conveying belt is changed depending on the curling direction of the transfer material, and this mode is applicable regardless of whether the curling direction of the transfer material is uneven. Since the transfer material can be stably fed into the fixing device, the processing performance of the transfer material can be improved.

  The invention of (5) is an image forming apparatus comprising the transfer material conveying device having the configuration described in the above (2) to (4), and can stably provide a high-quality recorded matter.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic diagram showing the configuration of an image forming apparatus composed of a digital color copying machine.

  The image forming apparatus shown in the figure has an automatic document feeder 1 at the top of the apparatus main body, and includes an image reading unit 2, an image forming unit 3, a belt installation unit for a belt unit 4, a paper feeding unit 5, and a fixing device. T, reverse paper discharge / refeed unit 6, and ADU 7 which is reverse transport means.

  The automatic document feeder 1 is a device that feeds documents one by one, conveys them to an image reading position, and discharges the document after image reading to a predetermined location.

  The automatic document feeder 1 includes a document placing table 101 on which a document is placed, a document separating unit 103 for separating the placed document, a document transporting unit 105 for transporting the separated document, and discharging the transported document. A pair of rollers used to reverse the front and back surfaces of the original in the double-sided copy mode for reading the images on both sides of the original. The document reversing means 111 is provided.

  In view of the processing process, a plurality of documents (not shown) placed on the document placing table 101 are separated one by one by the document separating means 103, and the image reading position is passed through the document conveying section 105. It is conveyed toward.

  The document reading position is provided at a lower portion of the document conveying unit 105, where an image of the document is read through the slit 201 constituting the image reading device 2, and the read document is discharged from the document. The sheet is discharged onto the document discharge table 109 by the means 107.

  In the double-sided copy mode, the original document that has been read and transported on one side is conveyed by the document reversing means 111 in the direction indicated by the two-dot chain line arrow, and the original document is being bitten at the trailing edge in the direction of travel. The reverse rotation after the driving of the reversing unit 111 is stopped and the image is again guided to the image reading position via the document conveying unit 105, and then discharged onto the document discharge table 109 by the document discharge unit 107. Is done.

  The above process is repeated for the number of documents placed on the document placing table 101.

  The image reading device 2 includes a first mirror unit 205 and a first mirror 215 that are formed by integrating the slit 201, a lamp 213 for irradiating a document, and a first mirror 215 that reflects reflected light from the document. A second mirror unit 207 in which a second mirror 217 that reflects light and a third mirror 219 are integrated in a substantially V shape, and an image that forms an image of reflected light from the third mirror 219 on the image sensor. A lens 209 and a line-shaped image sensor (hereinafter referred to as a CCD) 211 that photoelectrically converts a light image formed by the imaging lens 209 to obtain image information are included.

  The image information is temporarily stored in a memory (not shown) after appropriate image processing.

  In a mode in which the document fed by the automatic document feeder 1 is read by the image reading device 2, the first mirror unit 205 and the second mirror unit 207 are fixed at positions as shown.

  The image signals for the respective colors read by the image reading device 2 are sequentially taken out from the memory and inputted as electric signals to the respective exposure optical systems which are electrostatic charge latent image forming means.

  The image forming unit 3 forms four image forming units (hereinafter referred to as image forming units) of yellow (Y), magenta (M), cyan (C), and black (BK) that form a toner image corresponding to a color separation image. ) 30.

  Each of the image forming units 30 includes, for example, an image carrier (hereinafter referred to as a photosensitive drum) 310 in which a photosensitive layer made of a resin such as polycarbonate containing an organic photoconductor is provided on a drum-shaped metal substrate. Scorotron charger 320, exposure optical system 330 as image writing means (synonymous with electrostatic charge latent image forming means), developing device 380 for developing electrostatic charge latent image, transfer means 340, photoconductor after transfer A cleaning device 350 including a blade (cleaning means) for cleaning the surface of the drum 310 is a main component.

  The developing device 380 stores a two-component developer including a magnetic carrier (hereinafter simply referred to as a carrier) and a non-magnetic toner (hereinafter simply referred to as a toner), and is fixed in position and has a plurality of magnetic poles in the circumferential direction. A developer carrying member (developing sleeve) having a rotatable and non-magnetic cylindrical shape incorporating a magnet in which the magnets are arranged is provided, but since this configuration is known per se, a detailed description thereof will be omitted.

  The exposure optical system 330 is an exposure unit composed of a laser optical system, and the transfer means 340 is opposed to a part of the peripheral surface of the photosensitive drum 310 via a rotating belt 401 described later. .

  Since the mechanical configuration of the four sets of image forming units described above is basically the same, the reference numerals are given only for one set of units, and the other units are omitted.

  Each of the image forming units 30 is provided with a flat surface (a stretched surface) A of a loop-shaped rotating belt (hereinafter referred to as an intermediate transfer belt) 401 that constitutes the belt unit 4 and is long in the belt installation portion. Are arranged in the order of yellow, magenta, cyan, and black from above.

  The intermediate transfer belt 401, support rollers 405, 406, 407, and a backup roller 410 that suspend the intermediate transfer belt so as to rotate are included in the belt unit 4, and the backup roller 410 includes the intermediate transfer belt. A secondary transfer unit is configured by a transfer roller 510 that is disposed so as to rotate while pressing the backup roller with 401 interposed therebetween.

  Image formation by the configuration of the image forming unit 30 and the belt unit 4 is performed as follows.

  As the image forming process starts, the surface of the photosensitive drum 310 that rotates counterclockwise is charged to a predetermined polarity by the charger 320.

  Next, the exposure optical system 330 performs exposure corresponding to the first color signal, that is, the yellow (Y) image signal, and a latent image corresponding to the (Y) image is formed on the photosensitive drum 310. Is done.

  The latent image is reversely developed by contact or non-contact development with a developer of the developing device 380 and converted into a toner image of (Y), and then transferred onto the intermediate transfer belt 401 by the action of the transfer unit 340.

  Image formation with other color signals, which is sequentially started after a predetermined time from the start of image formation with the first color signal, is performed in the same manner as described above, and each image of magenta (M), cyan (C), and black (BK). Each of the toner images is sequentially transferred so as to overlap with an image area where the toner image (Y) is formed, and a superimposed color toner image is formed on the intermediate transfer belt 401.

  On the other hand, the surface of the photosensitive drum 310 after completion of the transfer process is cleaned by the cleaning unit 350, and preparations for new image formation are made.

  Note that the start timing of each image forming process with respect to the photosensitive drum 310 or the intermediate transfer belt 401 is one side of the intermediate transfer belt 401, in the present embodiment, and the intermediate transfer belt 401. A registration sensor 413 provided in a section from a position where the transfer roller 510 is located to a position where the first set (yellow) image forming unit is provided is provided on the intermediate transfer belt 401. For example, time is measured starting from when a reference mark formed using paint is detected, and the (Y), (M), (C), and (BK) processes are sequentially started every predetermined time. It is configured.

  The detection signal from the registration sensor 413 is taken in, the time is monitored, and control related to individual processes is performed by a control unit (control means) S including a computer.

  Next, other configurations of the apparatus will be briefly described in connection with the processes from the transfer of the color toner image formed on the intermediate transfer belt to the transfer material and the ejection to the outside of the apparatus.

  At an appropriate timing corresponding to image formation on the intermediate transfer belt 401, a transfer material (hereinafter referred to as “paper”) P is a paper feed roller 503 (513, 513) that is positioned in a feed section 501 (511, 521) of the paper feed section 5. 523) and conveyed toward the registration roller 551 via the separation roller 506 and a plurality of conveying roller pairs R1 to R7 provided on the sheet feeding path.

  The paper P to be fed is a paper of a size designated on the operation panel 150 in which the number of recordings, a recording start button, a recording magnification, a toner density, and the like can be set, but other known techniques are used. Can also be selected.

  After the sheet P is brought into contact with the registration roller 551, the sheet P is fed again so as to overlap the color toner image area on the intermediate transfer belt 401 by resuming the rotation of the registration roller 551.

  Next, the sheet P is sent out from the nip portion while being pressed and clamped together with the intermediate transfer belt by the backup roller 410 and the transfer roller 510 in the secondary transfer portion. During this time, the color toner image on the intermediate transfer belt 401 is fed. Is transferred onto the paper P.

  It is desirable that an appropriate transfer bias voltage is applied to the transfer roller 510 during transfer.

  The sheet P on which the toner image has been transferred is separated from the intermediate transfer belt 401, adsorbed onto a conveyance belt (not shown) constituting the transfer material conveyance device 8, and conveyed toward the fixing device T.

  The details of the transfer material transport device 8 which is the subject of the present invention will be described later.

  The fixing device T includes a fixing roller T1 having a built-in fixing heater and a pressure roller T2 that rotates while being pressed against the fixing roller. The color toner forming the image is heated and pressed by both rollers. It is melted and fixed on the paper P.

  The paper P after the fixing process by the fixing device T is completed is conveyed by a paper discharge roller 603 provided downstream thereof, and is discharged onto a paper discharge tray provided outside the apparatus main body.

  On the other hand, the surface of the intermediate transfer belt 401 after the completion of the secondary transfer is cleaned by a cleaning unit 415 including a blade, and preparations for carrying a new toner image are made.

  In the figure, the solid line position of the path switching member 601 is a position held when the upper and lower surfaces of the paper P are reversed and discharged after the fixing process, and the broken line position is sent out from the fixing device as described above. This position is held when the sheet is discharged as it is.

  For example, in the reverse discharge of the paper P, the paper P sent out from the fixing device T is guided downward along the right side of the path switching member 601, and the rear end in the advancing direction is held by the roller pair 602. It is lifted by the reverse rotation of the roller pair 602 after being set in the closed state, passes through the left side of the switching member 601, reaches the paper discharge roller 603, and is discharged so as to be discharged by the paper discharge roller. Is done.

  Further, the behavior of the paper P in the double-sided copy mode using the ADU 7 is similar to that in the case of the reverse discharge. The paper P after the fixing process with the image formed on one side is moved along the right side of the switching member 601. Then, after stopping the conveyance with the rear end of the paper P in the traveling direction being sandwiched by the roller pair 605, the roller pair 605 is rotated in the reverse direction and is raised along the guide plate G, and a plurality of roller pairs The reversal of the paper P is achieved by leading to the ADU 7 having 701, 703, and 705.

  The image forming process for the second surface of the paper P is the same as described above, and any one of the above-mentioned is selected for the discharge after being sent out from the fixing device T.

  In the figure, P1, P2, and P3 are paper storage devices that can store a predetermined amount of paper P, and are configured to be pulled out toward the front side of the figure.

  Reference numeral 9 denotes an open / close door, which is operated when removing jammed paper (jam processing) generated in the vicinity of the reverse paper discharge / refeed unit 6.

  The opening / closing door 9 is pivotally supported by a fixed portion of the image forming apparatus main body at its lower end.

  Next, the configuration of the transfer material transport apparatus will be described with reference to FIGS.

  FIG. 2 is a schematic plan view of a transfer material conveyance device using two conveyance belts as transfer material conveyance means. FIG. 3 is an image of a mode in which a toner image formed on a photosensitive drum is directly transferred onto a transfer material. FIG. 4 is a side view illustrating the transfer material conveyance device when conveying a concave curled paper, and FIG. 5 is a side view illustrating a convex curled paper. FIG. 6 is a partial view showing an example of a mechanism for displacing the conveyor belt from the reference position to the positions shown in FIGS. 4 and 5.

  In the image forming apparatus shown in FIG. 1, the transfer surface of the sheet P after transfer is inclined upward. However, the basic structure of the transfer material transfer apparatus and the effect of the structure are substantially the same. In FIG. 3, the transfer material conveyance surface is shown as horizontal.

  Further, in the drawing, the same reference numerals are assigned to the same means or the same functions as the above-described means (members).

  In FIG. 2, reference numerals 801 and 802 are rotatable position fixing rollers provided on a fixing frame on the apparatus main body side, and 803 is located between the position fixing rollers 801 and 802, and from the reference position in the vertical direction (on the paper surface in FIG. 2). A common roller that can be linearly displaced (moved) in the front and back direction and is rotatable is shown.

  The position fixing roller 801 is a driving roller, and the other position fixing roller 802 and the common roller 803 are driven rollers to which power is transmitted via a conveying belt.

  The linear movement of the common roller 803 can be achieved with the following configuration.

  For example, on the fixed frame of the apparatus, a vertically long linear slit having a dimension that allows the common roller 803 to move is provided, and pins are provided at four positions on both sides of the slit.

  On the other hand, a pin on the fixed frame is fitted into a vertically long slit provided on a holder for rotatably supporting both ends of the common roller 803, and the holder is always attached downward with a spring. To force.

  And the bending part (cam follower function) provided in the lower part of the holder and the peripheral surface of the cam mechanically connected to the motor (drive source) are kept in pressure contact with the urging force of the spring (see FIG. 6). ).

  The linear moving mechanism of the common roller is not limited to the above, and can be achieved by a combination of many known techniques and means such as a combination of a worm and a worm wheel, a rack: pinion mechanism, a solenoid, a screw rod, and the like. Can do.

  A motor, a cam, a cam follower, a worm and a worm wheel, or the like for displacing the common roller 803 in a predetermined direction serves as a position displacement unit for the conveying belt via the common roller or the common roller.

  Reference numeral 804 denotes a gear provided at an end portion of the position fixing roller 801, which receives power from a drive system provided on the apparatus main body side.

  B1 to B3 are conveyance belts suspended on the rollers, and have a function of conveying the sheet P separated from the image carrier after transfer to the fixing device T.

  One end side (the side that can be stretched) of the conveyance belt B1 formed in a loop shape is suspended and held at a suspension position provided at a substantially central portion in the width direction of the position fixing roller 801.

  Further, the other end side of the transport belt B1 is suspended and held at a suspension position provided at a substantially central portion of the common roller 803.

  On the other hand, the conveyance belts B2 and B3 are located on both sides of the conveyance belt B1, and are suspended and held by the position fixing roller 802 and the common roller 803.

  The outer diameter of the position fixing rollers 801 and 802 at the belt suspension position is equal to the outer diameter of the common roller 803.

  The axial center positions of these roller groups have the same height as shown in FIG. 3, and the upper surfaces (paper suction conveying surfaces) of the conveying belts B1 to B3 are positioned on substantially the same horizontal plane as the reference position.

  The conveying belts B1 to B3 are provided with a large number of small holes h, and a suction force of a suction means described later is applied to the paper P to be adsorbed on the conveying belt.

  Reference numeral 805 denotes a guide plate, which has an appropriate notch so as not to hinder the rotation of the roller groups 801, 802, and 803, and occupies an inner position of the conveyor belt at a portion of the conveyor belt. It is fixed to the device fixing frame via both sides.

  A convex portion 810 is formed at an appropriate interval in the width direction of the guide plate 805, and the height position of the top is slightly lower than the height position of the conveyor belt.

  In addition, rectangular areas 815 to 817 indicated by broken lines in the areas of the respective conveyor belts indicate areas where suction means 820 including a suction fan acts (see FIG. 3).

  The suction means 820 is provided inside the loop of each of the conveyor belts B1 to B3 that form a series, and the periphery of the suction means 820 is partitioned into a box shape with the upper surface portion remaining.

  However, for example, it is possible to cover the areas 816 and 817 related to the conveyor belts B2 and B3 with one suction means.

  Here, “ream” means a structure including transport belts arranged at different positions in the paper transport direction.

  In other words, it can be said that the first series includes the transport belts B <b> 2 and B <b> 3, the position fixing roller 802, and the common roller 803 as viewed in the paper traveling direction.

  Further, it can be said that the second station has a structure including the conveyance belt B1, the common roller 803, and the position fixing roller 801.

  In the present specification, except for the case where it is necessary to specify a belt, such as the conveyance belt B1, for example, a belt portion in the sheet conveyance direction constituted by a plurality of conveyance belts is simply referred to as a conveyance belt for convenience of explanation. Sometimes expressed.

  In FIG. 3, S5 and S10 shown at positions before the registration roller 551 are detection means for detecting the direction and size of the curl of the paper P, and are composed of optical sensors.

  The detection output of the sheet accompanying the operation of the detection means S5 and S10 is photoelectrically converted and compared with, for example, a table stored in a memory, and the direction and size of the curl are determined.

  A series of controls such as the operation timing of the detection means, comparison and determination of detection outputs, and the operation of the transfer material conveying device 8 (meaning displacement of the common roller) based on the result are the control device (control means). ) Implemented by S.

  The fixing device T includes an upper guide T10 and a lower guide T20 at an entrance portion, and a leading end portion of a sheet conveyed by the transfer material conveying device 8 faces a nip portion N between the fixing roller T1 and the pressure roller T2. The structure which guides.

  In the embodiment, as shown in the drawing, the nip portion N has a position higher than the height position on the upper surface side (synonymous with the sheet conveying surface position) of the conveying belt. It can also be.

  The operation of the transfer material transport device 8 having the above-described configuration will be briefly described.

  The paper P that has been transported by an appropriate transport means detects the curl size at the leading edge of the paper or the curl direction of the irregularities in the manner described above by the detection means S5 and S10 that are put into operation in a timely manner. Then, it comes into contact with and stops at the registration roller 551 that has stopped driving.

  Next, the paper P is sent out toward the transfer region by the registration roller 551 that is driven at the timing at which the toner image region formed on the image carrier and the paper P overlap.

  The sheet P on which the toner image on the image carrier is transferred by the operation of the transfer unit is separated from the image carrier by the action of the separating unit, and then continuously conveyed by the transfer material conveyance device 8.

  At this time, since the suction unit 820 is in an operating state, the paper P is adsorbed onto the transport belt through the upper surface portions of the transport belts B1 to B3.

  At this time, when the output result of the detection means S5 and S10 determines that the curl of the paper P is “slight”, the upper surface of the transport belt is kept in the horizontal state (meaning the reference position).

  When the output result of the detection means is determined to be “large concave curl”, the drive source is activated, and the common roller 803 is moved from the reference position to a predetermined position below the reference position via the position displacement means. (See FIG. 4).

  That is, the upper surface of the conveyance belt constituted by the conveyance belts B1 to B3 is in a state where the central portion (intermediate portion) in the traveling direction of the paper P is recessed as viewed from the side surface.

  Conversely, when it is determined that the output result of the detecting means is “large convex curl”, the common roller 803 is moved from the reference position to a predetermined position above the reference position via the position displacing means (see FIG. 5).

  That is, the upper surface of the transport belt is convex in the central portion (intermediate portion) in the traveling direction of the paper P when viewed from the side.

  As described above, by making the upper surface of the conveying belt similar to the shape of the sheet in the conveying direction, the efficiency of attracting the curled sheet to the conveying belt can be improved.

  For example, even a thick and small-sized paper such as a postcard can be firmly adsorbed on the conveyance belt and conveyed.

  It is desirable that the relative relationship among the suction means 820, the guide plate 805, and the common roller is maintained when the position of the common roller 803 is moved.

  The sheet P transported by the transport belt is released from the action of the suction unit 820 immediately before the position fixing roller 801, and is sequentially separated from the transport belt and sent to the fixing device T1.

  At this time, the paper P having no curl or small curl reaches the nip portion N between the fixing roller T1 and the pressure roller T2 and is fixed while being guided by the surface of the lower guide T20.

  The concavely curled paper P is separated from the conveying belt, and reaches the nip portion N while being guided by the upper guide T10, and is fixed.

  Further, after the convex curled paper P is separated from the conveying belt, it reaches the nip portion while being guided by the lower guide T20 and is fixed.

  Next, another example of the transfer material conveying apparatus will be described with reference to FIGS.

  Note that the same means as the above-described means (members) are denoted by the same reference numerals, and redundant description is omitted as much as possible, and the basic configuration is understood in the description related to FIG. As it seems, the different components are mainly briefly described.

  FIG. 7 is a schematic plan view of a transfer material conveyance device using a triple conveyance belt as a transfer material conveyance unit. FIG. 8 is an image of a mode in which a toner image formed on a photosensitive drum is directly transferred onto a transfer material. FIG. 9 is a side view for explaining the state of the transfer material conveying device when conveying the concave curled paper, and FIG. 10 is a side view showing the convex curled paper. FIG. 6 is a side view showing an aspect of the transfer material transport device during the transport of FIG. 2 and corresponds to FIGS. 2 to 5 of the first example.

  In the transfer material conveyance device 8 shown in FIG. 7, conveyance belts B5 and B6 are suspended between the position fixing roller 801 and the common roller 830 at an appropriate interval in the axial direction.

  Further, the conveyance belt B 7 is suspended between the common rollers 830 and 835, and the conveyance belts B 8 and B 9 are suspended between the common roller 835 and the position fixing roller 802.

  The conveyor belts B5, B6 and B8, B9 are arranged in substantially the same area in the axial direction, and the conveyor belt B7 is an area corresponding to the area between the conveyor belts B5, B6 (conveyor belts B8, B9) on the shaft. It is arranged.

  Between the two common rollers is a guide plate 884.

  Each of the conveyor belts is provided with a large number of small holes, and suction means 820 is provided inside each of the loop-shaped conveyor belts (see FIG. 8).

  The reference position of the transfer material transport device 8 is as shown in FIG. 8, and the paper transport surface of the transport belt is kept horizontal.

  The common rollers 830 and 835 can move linearly integrally from the reference position to the upper position and the lower position with respect to the fixed frame on the apparatus main body side, and the displacement is basically the same as in FIG. This can be achieved with the same configuration.

  The operation of the transfer material transport device 8 having such a configuration is the same as that of the first example, and according to the detection results by the detection means S5 and S10, that is, in the curl size and the curl direction of the paper P. Correspondingly, if the size of the curl is such that it does not hinder the conveyance, etc., it is placed at the reference position, and when it is “large concave curl”, it is moved to a predetermined position (see FIG. 9) below the reference position. In the case of “large convex curl”, it is moved to a predetermined position above the reference position (see FIG. 10).

  As described above, by making the upper surface of the transport belt (paper transport surface) similar to the shape of the paper in the transport direction, the efficiency of attracting the curled paper to the transport belt can be improved.

  For example, a thick and small-sized paper such as a postcard can be firmly adsorbed and conveyed on the conveyance belt, and can be stably fed into the fixing device.

  As described above, it is preferable that the common roller 803 is configured to maintain the relative relationship among the suction unit 820, the guide plates 805 and 840, and the common roller when the position of the common roller 803 is moved. This is not necessary when a predetermined suction force can be obtained on the surface.

  In the above example, the transfer material conveying apparatus having two and three consecutive conveying units has been described, but it goes without saying that the number of reams can be appropriately increased to four or five as necessary.

  In this case as well, the basic technical idea is the same as in the above embodiment, and the rollers disposed at both ends for suspending the conveyor belt are position fixing rollers, and the other rollers can be displaced by a common roller.

  Further, the number or size of the conveying belt in the axial direction can be determined as appropriate, and the degree of freedom in design is wide.

  Further, instead of providing a suction fan as a suction means in the loop of the transport belt, both portions are arranged so that the suction force of the suction fan installed on the apparatus body side acts on the paper transport surface of the predetermined transport belt. It can also be set as the structure connected with a duct.

  Note that the amount of displacement of the conveyor belt via the common roller can be determined as appropriate based on experimental data.

1 is a schematic diagram illustrating a configuration of an image forming apparatus including a digital color copying machine. FIG. 3 is a schematic plan view of a transfer material conveyance device using two conveyance belts as transfer material conveyance means. FIG. 3 is an explanatory side view including the vicinity of a transfer material conveyance device when an image forming apparatus is configured to directly transfer a toner image formed on a photosensitive drum onto a transfer material. FIG. 10 is a side view illustrating an aspect of a transfer material transport device when transporting a concave curled sheet. FIG. 6 is a side view showing an aspect of a transfer material transport device during transport of convex curled paper. It is a fragmentary figure which shows an example of the mechanism which displaces the position of a conveyance belt. FIG. 3 is a schematic plan view of a transfer material conveyance device using a triple conveyance belt as a transfer material conveyance unit. FIG. 3 is an explanatory side view including the vicinity of a transfer material conveyance device when an image forming apparatus is configured to directly transfer a toner image formed on a photosensitive drum onto a transfer material. FIG. 10 is a side view illustrating an aspect of a transfer material transport device when transporting a concave curled sheet. FIG. 6 is a side view showing an aspect of a transfer material transport device during transport of convex curled paper.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Automatic document feeder 2 Image reading part 3 Image formation part 4 Belt unit 5 Paper feed part 8 Transfer material conveyance apparatus 801,802 Position fixing roller 803,830,835 Common roller 820 Suction means B1, B2, B3, B5, B6 , B7, B8, B9 Conveyor belt

Claims (7)

In the transfer material transport method in the image forming apparatus that transports the transfer material separated from the image carrier toward the fixing unit while adsorbing the transfer material to the transport belt,
The curling state of the transfer material is detected by the detecting means, and the control means is controlled so as to convey the transfer material in a state where the central portion of the conveying belt is displaced upward or downward from the reference position according to the curled state. A transfer material conveying method characterized by: In the transfer material conveying apparatus configured to convey the transfer material separated from the image carrier toward the fixing unit while adsorbing the transfer material to the conveyance belt,
When viewed in the transfer material conveyance direction, the conveyance belt is constituted by a plurality of stations, and only two conveyance belt suspension rollers positioned at both ends thereof are fixed in position, and the conveyance belt suspension provided between the position fixing rollers is fixed. The common roller can be displaced, and
When the curling state of the transfer material is detected by the detecting means, and the curled state is a convex curl, the common roller provided so as to be movable up and down is displaced upward via the position displacing means, and When the curled state is a concave curl, the transfer material conveying device is configured to be controlled by the control means so that the common roller is displaced downward via the position displacement means. In the transfer material conveying apparatus configured to convey the transfer material separated from the image carrier toward the fixing unit while adsorbing the transfer material to the conveyance belt,
When viewed in the transfer material conveyance direction, the conveyance belt is configured in two, and one end side of each conveyance belt is provided on the position fixing rollers provided at both ends, and a common roller provided between the position fixing rollers. Suspend the other end of each conveyor belt,
When the curling state of the transfer material is detected by the detecting means, and the curled state is a convex curl, the common roller provided so as to be movable up and down is displaced upward via the position displacing means, and When the curled state is a concave curl, the transfer material conveying device is configured to be controlled by the control means so that the common roller is displaced downward via the position displacement means. In the transfer material conveying apparatus configured to convey the transfer material separated from the image carrier toward the fixing unit while adsorbing the transfer material to the conveyance belt,
As seen in the transfer material conveyance direction, the conveyance belt is configured in triplicate,
One end side of the first and second conveying belts positioned on both end sides is suspended from the position fixing rollers provided at both ends, and the side closer to the two common rollers provided between the position fixing rollers Suspend the other end side of each of the first and second transport belts to a common roller located at a position, and further suspend a third transport belt to the two common rollers,
When the curling state of the transfer material is detected by the detecting means, and the curled state is a convex curl, the common roller provided so as to be movable up and down is displaced upward via the position displacing means, and When the curled state is a concave curl, the transfer material conveying device is configured to be controlled by the control means so that the common roller is displaced downward via the position displacement means. 5. The transfer material transport apparatus according to claim 2, wherein a suction unit that adsorbs the transfer material to the transport belt is provided inside the transport belt forming each series. 5. The transfer material according to claim 2, wherein the suction means for adsorbing the transfer material to the transport belt is a suction fan connected to a duct provided inside the transport belt constituting each station. Conveying device. An image forming apparatus comprising the transfer material conveying device according to claim 2.

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