JP5178082B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus equipped with an intermediate transfer belt or a recording material conveyance belt, and more particularly to control for cleaning edge contamination of a belt member accompanied by steering control.

  A full-color image forming apparatus that performs secondary transfer of a plurality of color toner images carried on an intermediate transfer belt to a recording material has been put into practical use. In addition, a full-color image forming apparatus in which monochromatic toner images are sequentially transferred onto a recording material carried on a recording material conveyance belt and superimposed on the recording material has been put into practical use.

  An image forming apparatus has been put into practical use in which a belt member such as an intermediate transfer belt or a recording material conveying belt is steering-controlled to dynamically position the rotating belt member within a predetermined range in the axial direction of a support rotating body.

  Patent Document 1 discloses an image forming apparatus in which black, cyan, magenta, and yellow image forming units are arranged in a straight section of a recording material conveyance belt. Here, the recording material conveyance belt wound around a plurality of rollers is protruded from the inside by a steering roller, the inclination angle of the steering roller is adjusted by a motor, and the rotating recording material conveyance belt is set in a predetermined range in the axial direction of the roller. Is positioned.

  Patent Document 2 discloses an image forming apparatus in which yellow, magenta, cyan, and black image forming units are arranged in a straight section of an intermediate transfer belt. Here, the steering angle of the intermediate transfer belt is controlled by adjusting the tilt angle of the steering roller based on the output of the belt edge detection sensor that detects the edge of the intermediate transfer belt.

  In an image forming apparatus equipped with a belt member that performs steering control, the cleaning region of a cleaning device that removes toner from the belt member is usually set shorter than the width of the belt member.

  This is because when the cleaning blade is used, the rubbing state becomes unstable outside the image forming region where the toner is not supplied to the tip of the cleaning blade as compared with the inner region where the toner is supplied in abundant amount.

  Further, if the sliding length of the cleaning member is minimized according to the image forming area and the developing area, the frictional resistance of the cleaning member can be reduced and the driving power of the belt member can be saved.

  Further, if the cleaning region steadily protrudes to the outside of the belt member due to the reciprocating movement accompanying the steering control, problems such as damage to the edge of the cleaning blade, hair removal of the fur brush, and twisting of the cleaning web occur.

  Patent Document 3 discloses an electrostatic cleaning device that applies high voltages having different polarities to a pair of fur brushes that rotate and contact an intermediate transfer belt, and electrostatically adsorbs and removes toner adhering to the intermediate transfer belt. Indicated.

JP-A-6-56294 JP 2002-2999 A JP 2002-207403 A

  Even if the edge region of the belt member is located outside the image forming region and the developing region, the toner and paper dust gradually adhere to each other by repeated operation over many years and toner replacement. Toner and paper powder that escapes the cleaning by the cleaning device and moves around the edge area of the belt member can easily move to the image forming area with a small impact or air flow, causing image contamination or particulate image defects. Become.

  For this reason, it is necessary to manually clean the edge region of the belt member that is not normally cleaned during regular maintenance. In some cases, a dedicated cleaning device for cleaning only the edge region of the belt member may be provided at a position away from the cleaning device so as to avoid the above-described problems.

  However, when performing manual cleaning regularly, cleaning may be too late. This is because when a large amount of full-color images with a large amount of toner are continuously formed, the amount of steady toner scattering in the machine body increases and the contamination of the edge region of the belt member proceeds rapidly.

  Further, when a dedicated cleaning device is provided in the edge region of the belt member, the number of parts and maintenance locations increase, which results in counteracting downsizing of the image forming apparatus and reduction of maintenance costs.

  An object of the present invention is to provide an image forming apparatus that can clean an edge region of a belt member and prevent image contamination and the like without requiring a dedicated cleaning device or regular maintenance work.

The image forming apparatus according to the present invention includes a belt member that is supported by a plurality of support rotating bodies and rotates, and the length of the support rotating body in the axial direction is shorter than that of the belt member. A cleaning means for cleaning toner adhering to the member; a steering means for moving the rotating belt member in the axial direction; a detecting means for detecting the axial position of the belt member; and the detection during image formation. The belt member is controlled so that the steering means is in contact with the belt member in a first range of the belt member shorter than the belt member in the axial direction by controlling the steering means based on a detection result of the means. the by controlling the steering means based on the detection result the first control means and, before Symbol detection means for moving in the axial direction As the cleaning means in a second range of long the belt member than said first range in the axial direction abuts against the belt member, and a second control means for moving the belt member in the axial direction It is a thing. Then, the second control means controls the steering means during non-image formation to move the belt member to 1 while the one end portion of the second range of the belt member reaches the cleaning blade. It is possible to execute a cleaning mode in which the belt member is rotated one or more times in a state in which the belt member is rotated more than once and then the steering unit is controlled to reach the other end of the second range to the cleaning blade. .

  In the image forming apparatus of the present invention, during the non-image formation, the steering unit is controlled to move the belt member in the width direction between both outer positions of the movement range during the image formation. As a result, the cleaning range by the cleaning means is expanded by the length obtained by subtracting the moving range on one side during image formation from the outer position than during image formation.

  Thus, the toner accumulated outside the cleaning range of the cleaning unit during image formation can be removed by the same cleaning unit during non-image formation.

  Accordingly, the edge region of the belt member can be cleaned without requiring a dedicated cleaning device or periodic maintenance work, and image contamination due to toner or the like accumulated in the edge region can be prevented.

  Hereinafter, some embodiments of the present invention will be described in detail with reference to the drawings. As long as the belt member is reciprocated in the width direction by using the steering mechanism to clean both edge regions of the belt member, some or all of the configurations of the embodiments are replaced with the alternative configurations. Other embodiments replaced with can also be implemented.

  Therefore, the present invention is not limited to the image forming apparatus using the intermediate transfer belt, and can be implemented by an image forming apparatus that transfers a toner image to a recording material carried on a recording material conveyance belt. Not only a tandem type image forming apparatus in which a plurality of photosensitive drums are arranged along the belt member, but also a single drum type image forming apparatus in which one photosensitive drum is arranged. The belt cleaning device is not limited to the cleaning blade method, and may be replaced with an electrostatic cleaning device or a web cleaning device, or a plurality of methods may be used in combination.

  In the present embodiment, only main parts related to toner image formation / transfer will be described. However, the present invention includes a printer, various printing machines, a copier, a fax machine, a composite machine, in addition to necessary equipment, equipment, and a housing structure. It can be implemented in various applications such as a machine.

  In addition, about the general matter of the image forming apparatus shown by patent document 1, illustration is abbreviate | omitted and the overlapping description is abbreviate | omitted.

<First Embodiment>
FIG. 1 is an explanatory diagram of a configuration of the image forming apparatus according to the first embodiment, and FIG. 2 is an explanatory diagram of a configuration of an image forming unit and a secondary transfer unit.

  As shown in FIG. 1, the image forming apparatus 100 according to the first embodiment is a tandem type full-color copying machine in which four image forming units Pa, Pb, Pc, and Pd are arranged in a straight section of the intermediate transfer belt 9.

In the image forming portion Pa, a yellow toner image is formed on the photosensitive drum 1 a and is primarily transferred to the intermediate transfer belt 9. In the image forming unit Pb, a magenta toner image is formed on the photosensitive drum 1 b and is primarily transferred to the yellow toner image on the intermediate transfer belt 9 . In the image forming portions Pc and Pd, a cyan toner image and a black toner image are formed on the photosensitive drums 1c and 1d, respectively, and are sequentially primary-transferred on the intermediate transfer belt 9 in order.

The four-color toner images primarily transferred to the intermediate transfer belt 9 are transported to the secondary transfer portion T2 and collectively transferred to the recording material P. The recording material P on which the four-color toner image is secondarily transferred by the secondary transfer portion T2 is heated and pressed by the fixing device 25 and fixed on the surface, and then discharged to the outside of the image forming apparatus 100. Is done.

  The separation device 22 separates the recording material P drawn from the paper feed cassette 20 by the pickup roller 21 one by one and sends it to the registration roller 23.

  The registration roller 23 receives and waits for the recording material P in a stopped state, sandwiches and conveys the recording material P in synchronization with the toner image carried on the intermediate transfer belt 9, and sends it to the secondary transfer portion T2.

  The image forming portions Pa, Pb, Pc, and Pd are configured in the same manner except that the color of toner used in the attached developing devices 4a, 4b, 4c, and 4d is different from yellow, magenta, cyan, and black. Hereinafter, the image forming unit Pa will be described, and the other image forming units Pb, Pc, and Pd will be described by replacing “a” at the end of the reference numerals with “b”, “c”, and “d”.

  As shown in FIG. 2, the image forming unit Pa includes a charging device 2a, an exposure device 3a, a developing device 4a, a primary transfer roller 5a, and a cleaning device 6a around the photosensitive drum 1a.

  The photosensitive drum 1a is configured by applying an organic photoconductor layer (OPC) having a negative polarity to the outer peripheral surface of an aluminum cylinder. The photosensitive drum 1a transmits driving force from a driving motor (not shown) and rotates in the direction of arrow R1 at a process speed of 300 mm / sec.

  The charging device 2a presses the charging roller against the photosensitive drum 1a to be driven to rotate, and applies a voltage obtained by superimposing a DC voltage and an AC voltage to the charging roller from the power source D3, so that the surface of the photosensitive drum 1a has a uniform negative electrode. It is charged to a sex potential.

  The exposure device 3a scans the scanning line image data obtained by developing the yellow separated color image with a rotating mirror, and writes an electrostatic image of the image on the surface of the charged photosensitive drum 1a.

  The developing device 4a agitates a two-component developer obtained by mixing a magnetic carrier with toner and charges the toner negatively. The charged toner is carried on the developing sleeve 4s rotating around the fixed magnetic pole 4j in the counter direction with the photosensitive drum 1a, and rubs against the photosensitive drum 1a.

  The power source D4 applies a voltage obtained by superimposing an AC voltage to a negative DC voltage to the developing sleeve 4s, and moves the toner to the electrostatic image on the photosensitive drum 1a that has a relatively positive polarity relative to the developing sleeve 4s. Then, the electrostatic image is reversely developed.

  The primary transfer roller 5 a sandwiches the intermediate transfer belt 9 between the photosensitive drum 1 a and forms a primary transfer portion T 1 between the photosensitive drum 1 a and the intermediate transfer belt 9.

The primary transfer roller 5a is composed of a core metal having a diameter of 8 mm and a conductive urethane sponge layer having a thickness of 4 mm. The primary transfer roller 5a rotated at a peripheral speed of 50 mm / sec under a load of 5 N (500 gf) was brought into contact with a metal roller with a ground potential, and a current of 500 V was applied to the metal core to measure the current. The value was 10 ⁵ Ω (23 degrees C50% RH).

  The power supply D1 applies a positive DC voltage to the roller shaft of the primary transfer roller 5a, charges the toner image negatively charged and carried on the photosensitive drum 1a, and passes the primary transfer portion T1 to the intermediate transfer belt 9 that passes through the primary transfer portion T1. Move it electrically.

  The cleaning device 6a slides the cleaning blade on the photosensitive drum 1a to remove the transfer residual toner that has passed through the primary transfer portion T1 and remained on the surface of the photosensitive drum 1a.

  The secondary transfer roller 11 is pressed against the backup roller 10 via the intermediate transfer belt 9 to form a secondary transfer portion T <b> 2 between the intermediate transfer belt 9 and the secondary transfer roller 11. The toner image moves from the intermediate transfer belt 9 to the recording material in the process in which the recording material P passes through the secondary transfer portion T2 while being superimposed on the toner image of the intermediate transfer belt 9.

  The backup roller 10 is made of a stainless steel cylindrical material and connected to the ground potential.

The secondary transfer roller 11 has an elastic layer 11b disposed on the outer periphery of a stainless steel roller shaft 11a. The elastic layer 11b has a volume resistance adjusted to 10 ⁶ to 10 ⁸ Ω · cm by dispersing stearyltrimethylammonium, which is an ion conductive resistance control agent, in a foamable synthetic rubber material (NBR).

  The power source D2 applies a positive constant voltage to the roller shaft 11a of the secondary transfer roller 11 and supplies a transfer current to the series circuit of the backup roller 10, the intermediate transfer belt 9, the recording material P, and the secondary transfer roller 11. Shed. A part of the transfer current flows through the toner mounting portion of the intermediate transfer belt 9 and is involved in the movement of the toner from the intermediate transfer belt 9 to the recording material P.

<Intermediate transfer belt>
As shown in FIG. 1, the intermediate transfer belt 9, which is an example of a belt member, carries a toner image primarily transferred by the primary transfer portion T <b> 1 and performs secondary transfer to the recording material P. Transport to T2. The intermediate transfer belt 9 is supported by the driven roller 12, the driving roller 13, the steering roller 40, and the backup roller 10, and is driven by the driving roller 13 to rotate in the direction of arrow R2 at a process speed of 300 mm / sec. The intermediate transfer belt 9 is given a tension of 50 N (5 kgf) by a steering roller 40 that also serves as a tension roller.

The intermediate transfer belt 9 is formed in an endless shape having a width of 370 mm, a circumferential length of 900 mm, and a thickness of 100 μm using a dielectric resin material such as PC, PET, and PVDF. The volume resistivity of the intermediate transfer belt 9 is adjusted to 10 ^8.5 Ω · cm (using a probe conforming to JIS-K6911 method, applied voltage 100 V, applied time 60 sec, 23 degrees C50% RH). However, other materials, volume resistivity, thickness, etc. may be used.

  The belt cleaning device 19 slides a polyurethane rubber cleaning blade 19b against the intermediate transfer belt 9 to remove residual toner remaining on the intermediate transfer belt 9 after passing through the secondary transfer portion T2. The contact pressure of the cleaning blade 19b in the belt cleaning device 19 was 10 N (1000 gf).

<Steering mechanism>
3 is a plan view of the steering mechanism, FIG. 4 is an explanatory view of the steering cam, and FIG. 5 is an explanatory view of the operation of the steering mechanism. In FIG. 4, (a) is a cam curve, (b) is the relationship between the rotation angle and the cam displacement, and (c) is the relationship between the rotation angle and the shifting speed. In FIG. 5, (a) is a state reversed from the front side, and (b) is a state reversed from the back side.

  As shown in FIG. 1, the steering mechanism 30 rotates the pair of support arms 35 and 45 about the rotation shaft 34 by rotating the steering cams 33 and 43. As a result, the steering roller 40 pivotally supported at the tips of the support arms 35 and 45 is inclined, the winding angle of the intermediate transfer belt 9 is changed, and the rotating intermediate transfer belt 9 is moved in the axial direction of the drive roller 13. .

  As shown in FIG. 3, the pair of support arms 35 and 45 are rotatably attached to the rotation shaft 34 fixed to the belt unit frames 55 and 56.

  The support arm 35 on the near side supports the roller arm 38 so as to be slidable in a direction along the support arm 35 by a guide rail 37 attached to the front end side. The roller arm 38 is urged in the direction of protruding outward by the spring 36 to apply the above-described tension to the intermediate transfer belt 9.

  The support arm 45 on the back side supports the roller arm 48 so as to be slidable in a direction along the support arm 45 by a guide rail 47 attached to the tip side. The roller arm 48 is urged in the direction of protruding outward by the spring 46 to apply the above-described tension to the intermediate transfer belt 9.

  The cam shaft 44 that is pivotally supported by the belt unit frames 55 and 56 is driven by a steering motor 53 to rotate the steering cams 33 and 43 integrally. The steering motor 53 is composed of a pulse motor, and rotates and stops in the rotation direction corresponding to the sign of the input signal by the rotation angle corresponding to the number of input pulses, and holds the rotation angle.

  The belt position detection sensors 51 and 52, which are examples of detection means, are actually disposed inside the intermediate transfer belt 9 and detect the belt edge. The controller 110 controls the tilt angle of the steering roller 40 based on the detection results of the belt position detection sensors 51 and 52.

  The belt position detection sensors 51 and 52 detect the reflected light from the inner surface of the intermediate transfer belt 9 by irradiating infrared light converged by the lens. Each of the belt position detection sensors 51 and 52 includes an inner detection unit used for normal deviation control and an outer detection unit used for belt edge cleaning control.

  In the normal shift control as an example of the first control means, the steering is performed so that the intermediate transfer belt 9 reciprocates between the inner side detection unit of the belt position detection sensor 51 and the inner side detection unit of the belt position detection sensor 52. The inclination angle of the roller 40 is automatically adjusted.

  In the belt edge cleaning control as an example of the second control means, steering is performed so that the intermediate transfer belt 9 reciprocates between the outer side detection unit of the belt position detection sensor 51 and the outer side detection unit of the belt position detection sensor 52. The inclination angle of the roller 40 is automatically adjusted.

  The function as the first control means and the function as the second control means are realized by different parts of the common program flow processed by the control unit 110.

  As shown in FIG. 4A, the steering cam 33 rotates about the cam shaft 44 and rotates the support arm (35: FIG. 3) according to the side surface irregularities. A steering cam (43: FIG. 3) (not shown) is formed symmetrically with the steering cam 33 and is mounted symmetrically.

  When the steering cam 33 is rotated by an angle θ with the clockwise direction as the positive direction, the cam displacement X gradually increases as shown in FIG. 4B, and the intermediate transfer is performed as shown in FIG. 4C. The belt shifting speed of the belt (9: FIG. 3) increases linearly. At this time, the steering cam 33 is also rotated integrally to gradually reduce the cam displacement, and the support arm 45 shown in FIG. 3 is rotated in the direction opposite to the support arm 35.

  As shown in FIG. 5A, when the belt position detection sensor 51 detects the reflected light from the intermediate transfer belt 9, the controller 110 determines that the intermediate transfer belt 9 has reached the limit of the near side position. to decide. The control unit 110 operates the steering motor 53 to rotate the steering cams 33 and 43 to incline the steering roller 40, thereby reversing the direction of the intermediate transfer belt 9 in the direction of the arrow and moving it to the back side. Start moving.

  As shown in FIG. 5B, when the belt position detection sensor 52 detects the reflected light from the intermediate transfer belt 9, the controller 110 determines that the intermediate transfer belt 9 has reached the limit of the rear side shift position. to decide. The control unit 110 operates the steering motor 53 to rotate the steering cams 33 and 43 in the direction opposite to that shown in FIG. 5A, and tilts the steering roller 40 in the direction opposite to that shown in FIG. Let As a result, the direction toward the intermediate transfer belt 9 is reversed in the direction of the arrow, and the movement toward the front side is started.

<Belt edge cleaning control>
6 is an explanatory diagram of belt edge cleaning control, FIG. 7 is an explanatory diagram of a belt position detection sensor, FIG. 8 is an explanatory diagram of steering control in belt edge cleaning, and FIG. 9 is a flowchart of belt edge cleaning control.

  As shown in FIG. 6, in the first embodiment, the belt width of the intermediate transfer belt 9 is 360 mm with respect to the steering roller width 370 mm of the steering roller 40.

  During continuous image formation, the intermediate transfer belt 9 reciprocates between the inner side detection unit 51 i of the belt position detection sensor 51 and the inner side detection unit 52 i of the belt position detection sensor 52. The intermediate transfer belt 9 is steering-controlled between the front limit position D1 and the back limit position D2 with an amplitude of ± 5 mm between the inner detection section 51i and the inner detection section 52i.

  The image forming area is set to 300 mm corresponding to the A3 lateral feed, and the cleaning blade 19b of the belt cleaning device 19 shown in FIG. 1 has a length of 330 mm.

  Therefore, the cleaning blade 19b cleans the cleaning and cleaning possible area of 330 mm ± 5 mm at the center of the intermediate transfer belt 9, but does not clean the 10 mm area from both edges. This is because the toner is supplied enough and the cleaning blade 19b is rubbed in a range where the friction load is small, so that the running of the intermediate transfer belt 9 is stabilized and the driving power of the intermediate transfer belt 9 is also saved.

  Here, if the length of the cleaning blade 19b is set to 350 mm, the entire 360 mm width of the intermediate transfer belt 9 can be cleaned with normal shift control.

  However, since the toner is not supplied to the tip of the cleaning blade 19b outside the image forming area, the sliding of the cleaning blade 19b becomes unstable. At a high process speed, there is a possibility that the cleaning blade 19b generates chatter vibration and deteriorates the cleaning performance. The toner in the image forming area does not reach every corner of the cleaning blade 19b under normal shift control.

  For this reason, when image formation is continued for a long time, toner, paper dust, external additives, dust, and the like gradually accumulate and follow in areas of 10 mm from both edges of the intermediate transfer belt 9.

  When the toner is exchanged, jammed, the secondary transfer roller is exchanged, the parts of the cleaning device are exchanged, or the maintenance is performed, the toner that has moved inside the apparatus may adhere to the intermediate transfer belt 9 in some cases.

  Therefore, in the first embodiment, when the continuous image formation exceeds 500 sheets, the image formation is interrupted and the belt edge cleaning control is executed.

  During belt edge cleaning control, the intermediate transfer belt 9 reciprocates between an outer side detection unit 51e of the belt position detection sensor 51 and an outer side detection unit 52e of the belt position detection sensor 52, which are provided corresponding to the outer position. . The intermediate transfer belt 9 has an amplitude of ± 15 mm between the front side limit position E1 where the outer side detection unit 51e detects the belt edge and the back side limit position E2 where the outer side detection unit 52e detects the belt edge. Steering controlled.

  Accordingly, the cleaning blade 19b of the belt cleaning device 19 shown in FIG. 1 performs cleaning by reciprocating the entire width region of 330 mm ± 15 mm = 360 mm in the center of the intermediate transfer belt 9. By using the toner adhered through the image formation of 500 sheets as a lubricant, the cleaning blade 19b is stably rubbed even in the edge region of the intermediate transfer belt 9, whereby the toner, paper dust and the like are efficiently removed.

  As shown in FIG. 7, in the normal shift control, the intermediate transfer belt 9 is moved at the timing when the inner detection unit 51i of the belt position detection sensor 51 provided corresponding to the movement range at the time of image formation detects the reflected light. The movement starts to the opposite side. At this time, as shown in FIG. 4, the steering cam 33 (43) is gently rotated in a range of ± 3 degrees to ± 10 degrees centering on 0 degree, and the cam displacement X is 0.1 mm to 0.3 mm. It is.

  As a result, the intermediate transfer belt 9 gently stops moving in the width direction and slowly starts moving in the opposite direction, and then continues to move in the opposite direction at a very low moving speed. When the intermediate transfer belt 9 moves in the width direction at a high moving speed during image formation, the toner images of the image forming portions Pa, Pb, Pc, and Pd shown in FIG. 1 are displaced in the width direction and the image quality deteriorates. It is. In normal shift control, the intermediate transfer belt 9 slowly moves from the near side limit position D1 to the back side limit position D2 in a long cycle of several tens of minutes to several hours.

  On the other hand, when the belt edge cleaning control is started, as shown in FIG. 4, the steering cam 33 (43) rotates at a maximum cutting angle of 90 degrees toward the rotation angle side viewed from 0 degrees. The cam displacement X reaches 3 mm. As a result, the intermediate transfer belt 9 is moved by increasing the moving speed in the direction toward which it was moved so that the limit position in that direction is quickly reached. This is because the belt edge cleaning control is promptly terminated without waiting for several tens of minutes to several hours, so as to return to the continuous image formation at an early stage.

  Then, at the timing when the outer side detection unit 51e of the belt position detection sensor 51 detects the reflected light, the normal shift control is inverted by ± 10 degrees so that the output of the outer side detection unit 51e is in an intermediate state between reflection and transmission. Repeat the rotation. In this manner, with the edge of the intermediate transfer belt 9 positioned at the front limit position E1, the intermediate transfer belt 9 is rotated one or more times to clean the edge region without leakage.

  Immediately thereafter, the steering cam 33 (43) is rotated 90 degrees at the maximum cutting angle toward the angle side toward the back side limit position E2, and the intermediate transfer belt 9 is quickly moved to the back side limit position E2.

  Then, for example, at the timing when the outer side detection unit 52e of the belt position detection sensor 52 detects the reflected light, the same ± as the normal shift control is performed so that the output of the outer side detection unit 52e is in an intermediate state between reflection and transmission. Repeat 10 degree inversion. In this way, the intermediate transfer belt 9 is rotated one or more times in a state where the edge of the intermediate transfer belt 9 is positioned at the back side limit position E2, and the opposite edge region is cleaned without leakage once.

  As shown in FIG. 8A, during image formation, the intermediate transfer belt 9 reciprocates between the near side limit position D1 and the back side limit position D2, so that it is not cleaned outside the cleanable area. A region is formed, and toner and the like are attached and accumulated.

  However, at the time of non-image formation, the intermediate transfer belt 9 is held at least one turn at both end positions with a wide amplitude in the belt edge cleaning control.

  As shown in FIG. 9 with reference to FIG. 3, when the control unit 110 reaches 500 sheets which is an example of the specified number of sheets (YES in S11), the image forming is interrupted (S12), and the belt edge cleaning control is performed. Start.

  The control unit 110 moves the intermediate transfer belt 9 to the back side limit position E2 (S13), positions the intermediate transfer belt 9 to the back side limit position E2, and rotates it once (S14).

  As shown in FIG. 8B, when the intermediate transfer belt 9 is moved to the rear limit position E2 by the belt edge cleaning control, the edge region on the near side of the intermediate transfer belt 9 overlaps the cleaning-cleanable region. To be cleaned.

  When the controller 110 has completed one rotation (S14), the controller 110 moves the intermediate transfer belt 9 to the front limit position E1 (S15), positions the intermediate transfer belt 9 to the front limit position E1, and rotates it one turn (S15). S16).

  As shown in FIG. 8C, when the intermediate transfer belt 9 is moved to the front limit position E1 in the belt edge cleaning control, the inner edge region of the intermediate transfer belt 9 overlaps the cleaning-cleanable region. To be cleaned.

  When the controller 110 has completed one rotation (S16), the intermediate transfer belt 9 is moved between the front limit position D1 and the back limit position D2 (S17), and returned to normal steering control (S18). ).

  The control unit 110 resumes the interrupted image formation (S19), and repeats a series of controls (S11 to S19) including the image formation (S19) until the job ends (NO in S20).

  As described above, according to the first embodiment, the edge of the intermediate transfer belt 9 is detected using the shift control that detects the belt shift in the width direction of the intermediate transfer belt 9 and controls the tilt angle of the steering roller 40. The area can be cleaned. By increasing the tilt angle of the steering roller 40 and moving the intermediate transfer belt 9 until the cleanable area of the cleaning blade 19b reaches the edge area, both edge areas can be quickly cleaned.

<Modification of First Embodiment>
FIG. 10 is a flowchart of control according to the first modification. Modification 1 is implemented in the image forming apparatus 100 shown in FIGS. 1 to 8 by replacing a part of the control in FIG. 9, and thus steps common to FIG. Therefore, a duplicate description is omitted.

  As shown in FIG. 1, when the image forming apparatus 100 causes a jam and automatically stops, the operator opens the machine body, removes the jam sheet, and returns the machine body to its original state.

  As shown in FIG. 10 with reference to FIG. 3, when the control unit 110 detects the completion of the jam sheet removal operation (YES in S21), the control unit 110 starts a return rotation as a return operation after the jam processing (S22). In this return rotation, the control in steps S13 to S16 described in the first embodiment is executed.

  As shown in FIG. 1, in the first embodiment, when continuous image formation from the previous belt edge cleaning control reaches a specified number, the image formation is interrupted and the belt cleaning control is executed.

  In the second modification, when the specified time (120 minutes) elapses after the image forming apparatus 100 receives a job and starts continuous image formation, the control in steps S12 to S20 in the flowchart of FIG. 9 is executed.

  In the third modification, the image forming apparatus 100 receives a job, performs continuous image formation, and after the job is completed, the intermediate transfer belt 9 and the photosensitive drums 1a, 1b, 1c, and 1d are rotated after the return operation. Run. In the subsequent rotation, the control in steps S22 to S16 in the flowchart of FIG. 10 is executed.

  In the fourth modification, when the operator completes the toner replacement of the image forming apparatus 100, the image forming apparatus 100 performs a return rotation as a return operation after the toner replacement. In this return rotation, the control of steps S22 to S16 in the flowchart of FIG. 10 is executed.

  In the first embodiment, in order to clean the intermediate transfer belt 9, a belt cleaning device 19 that slides the cleaning blade 19b on the surface to be cleaned is installed.

  In the fifth modification, the belt cleaning device 19 is replaced with an electrostatic cleaning device. As shown in Patent Document 3, the electrostatic cleaning device applies high voltages of different polarities to a pair of fur brushes that rotate and contact the intermediate transfer belt, and electrostatically removes toner adhering to the intermediate transfer belt. Adsorption and removal can be employed. Other electrostatic cleaning devices may be employed.

  In the first embodiment, in order to detect the belt edge of the intermediate transfer belt 9, a pair of belt position detection sensors each having an inner detection portion and an outer detection portion are used.

  By setting the time lag from the detection of the belt edge by the inner side detection unit to the tilting of the steering roller in the reverse direction larger than the normal shift control, a large amplitude necessary for the belt edge cleaning control may be secured. .

  The sensor that detects the position of the intermediate transfer belt 9 in the width direction may be replaced with a sensor that detects an index mark provided on the belt member. The detection means may be an encoder that continuously detects the position of the intermediate transfer belt 9 in the width direction and generates different outputs depending on the position, instead of providing an independent inner detection section and outer detection section.

  By the way, in the image forming apparatus using the intermediate transfer belt, the toner and the like are removed and cleaned mainly by the cleaning member in the image forming area. For this reason, it is not possible to directly clean the edge region of the belt member where the cleaning member is not in contact, and the toner or paper dust scattered from the developing device, the cleaning device, the photosensitive drum, etc. floats and the edge of the intermediate transfer belt May adhere to the area.

  On the other hand, in order to clean the edge area of the intermediate transfer belt, the length of the cleaning member needs to be equal to or larger than the width of the intermediate transfer belt. Alternatively, the length of the cleaning member needs to be equal to or longer than the width obtained by subtracting the amplitude of the normal shift control from the width of the intermediate transfer belt.

  However, in the case of the cleaning blade, since the edge region of the belt member is a non-image forming region where no toner is placed, the friction coefficient increases locally, and the tip of the cleaning blade is locally localized in a high process speed model. Thermal degradation. If the coefficient of friction is high, the contact state of the cleaning blade becomes unstable, causing vibrations to deteriorate the cleaning performance, and turning or damaging the blade portion. A large load may be applied to the belt member from the cleaning blade, which may affect the running of the belt member.

  According to the first embodiment and the first to fifth modifications, this problem is solved by a simple control change using the existing steering mechanism 30.

Second Embodiment
FIG. 11 is an explanatory diagram of a configuration of the image forming apparatus according to the second embodiment. The second embodiment is configured and controlled in the same manner as in the first embodiment with respect to belt edge cleaning control of the belt member except that the belt member to be controlled by the steering is a recording material conveyance belt. Therefore, in FIG. 10, the same components as those in the first embodiment are denoted by the same reference numerals as those in FIG.

  As shown in FIG. 10, the image forming apparatus 200 according to the second embodiment is a tandem full-color copying machine in which four image forming units Pa, Pb, Pc, and Pd are arranged in a straight section of the recording material conveyance belt 9H. .

  In the image forming unit Pd, a black toner image is formed on the photosensitive drum 1d and transferred to the recording material P carried on the recording material conveyance belt 9H. In the image forming unit Pc, a cyan toner image is formed on the photosensitive drum 1c and transferred onto the black toner image on the recording material P carried on the recording material conveyance belt 9H. In the image forming portions Pb and Pa, magenta toner images and yellow toner images are formed on the photosensitive drums 1b and 1a, respectively, and similarly, sequentially superimposed on the toner images on the recording material P carried on the recording material conveyance belt 9H. Transcribed.

The recording material P onto which the four color toner images have been sequentially transferred is released from electrostatic attraction to the recording material transport belt 9H in the process of passing through the separation charger 8, and is separated from the recording material transport belt 9H by the drive roller 13. Is done. The recording material P onto which the four color toner images have been transferred is heated and pressurized by the fixing device 25 to fix the toner image on the surface, and then discharged to the outside of the image forming apparatus 200.

  The separation device 22 separates the recording material P drawn from the paper feed cassette 20 by the pickup roller 21 one by one and sends it to the transfer charger 23H.

  The transfer charger 23H transfers the recording material P to the recording material conveyance belt 9H in a charged state, and electrostatically attracts it.

  As the transfer charger 23H, a contact charger using a transfer charging member such as a blade, a roller, or a brush can be used. The contact charger has advantages such as ozonelessness, resistance to temperature and humidity fluctuations, and high image quality.

  It is known that the transfer charger 23H stabilizes the image when the current that contributes to the transfer is kept constant at an appropriate current. Therefore, it is common to perform constant current control so that a constant current can be obtained even when the volume resistance value changes depending on the type (thickness, material, etc.) of the recording material P, moisture absorption conditions, and the like.

  The separation charger 8 discharges the recording material P, onto which the four color toner images have been transferred, in a non-contact manner on the downstream side in the rotation direction of the recording material conveyance belt 9H, thereby generating an electrostatic adsorption force on the recording material conveyance belt 9H. Attenuate. In particular, in a low humidity environment, the recording material P is dried and the electric resistance is increased, so that the electrostatic adsorption force with the recording material conveyance belt 9H is increased, and the effect of the separation charger 8 is increased. The separation charger 8 is a non-contact charger for charging the recording material P in a state where the toner image is not fixed.

  The output of the separation charger 8 is an AC voltage having a peak-to-peak voltage Vpp of 10 kV and a frequency of about 500 Hz. In addition, in order to prevent image defects such as toner scattering, a positive or negative DC component of about 100 μA is superimposed on the AC output.

The recording material conveyance belt 9H is made of a dielectric resin such as PC, PET, PVDF. In the second embodiment, a PI resin having a volume resistivity of 10 ¹³ to 10 ¹⁸ Ω · cm (using a probe conforming to the JIS-K6911 method, an applied voltage of 100 V, an applied time of 60 sec, 23 ° C. 50% RH), and a thickness t = 100 μm is used. Adopted. However, other materials, volume resistivity, and thickness may be used.

  The image forming portions Pa, Pb, Pc, and Pd are as described in the first embodiment with reference to FIG. However, the secondary transfer portion T2 shown in FIG. 2 does not exist, and the primary transfer rollers 5a, 5b, 5c, and 5d are read as the transfer rollers 5a, 5b, 5c, and 5d.

  The recording material transport belt 9H is provided with a web cleaning device 26 for cleaning the recording material transport belt 9H by rubbing the cleaning web 27.

  The cleaning web 27 is loaded on the supply roller 26a in a roll shape.

  The cleaning roller 26b presses and cleans the cleaning web 27 drawn from the supply roller 26a against the surface of the recording material transport belt 9H with a predetermined pressure.

  The take-up roller 26c takes up the cleaning web 27 to which the toner or the like is adhered by the cleaning roller 26b.

  The web cleaning device 26 pulls out the cleaning web 27 by 2 mm from the supply roller 26a every time 25 images are formed, and collects the used portion onto the take-up roller 26c.

  The web cleaning device 26 removes residual charges on the recording material transport belt 9H by using a non-illustrated neutralizing roller connected to the ground potential. In addition to neutralizing the recording material conveyance belt 9H by applying a high voltage of about 2 to 4 kV to the neutralization roller, the recording material conveyance belt 9H at the end of the transfer may be reduced by charging it to a reverse potential. Good.

<Belt edge cleaning control>
In the image forming apparatus 200 of the second embodiment, a normal shift control and a belt edge cleaning control are executed using the steering mechanism 30 configured as shown in FIG.

  As shown in FIG. 8, the relationship among the image forming area, the cleaning / cleanable area, and the steering roller 40 on the recording material conveyance belt 9H is set. Belt position detection sensors 51 and 52 shown in FIG. 3 detect outer limit positions E1 and E2 used for belt edge cleaning control outside the inner limit positions D1 and D2 used for normal shift control.

  As shown in FIG. 9, in the second embodiment, when the number of continuous image formations after the previous belt edge cleaning control reaches 500 (YES in S11), the image formation is interrupted (S12), and the belt edge cleaning is performed. Control (S13 to S16) is executed. When the belt edge cleaning control (S13 to S16) is completed, the recording material conveyance belt 9H is returned to the normal shift control range (S17), and image formation is resumed (S19).

  The start timing of the belt edge cleaning control may be after a predetermined time has elapsed from the start of image formation, after jamming of the recording material, and at the time of post-rotation after completion of image formation.

It is explanatory drawing of a structure of the image forming apparatus of 1st Embodiment. It is explanatory drawing of a structure of an image formation part and a secondary transfer part. It is a top view of a steering mechanism. It is explanatory drawing of a steering cam. It is explanatory drawing of operation | movement of a steering mechanism. It is explanatory drawing of belt edge cleaning control. It is explanatory drawing of a belt position detection sensor. It is explanatory drawing of steering control in belt edge cleaning. It is a flowchart of belt edge cleaning control. 10 is a flowchart of control in Modification 1; It is explanatory drawing of a structure of the image forming apparatus of 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a Photosensitive drum 2a Charging device 3a Exposure device 4a Development device 5a Primary transfer roller 6a Cleaning device 9, 9H Belt member (intermediate transfer belt, recording material conveyance belt)
19 Cleaning means (belt cleaning device)
20 Paper feeding cassette 25 Fixing device 40 Steering means (steering roller)
51, 52 Belt detection means (belt position detection sensor)
100, 200 Image forming apparatus 110 First control means, second control means (control unit)

Claims (2)

A belt member that is supported by a plurality of support rotating bodies and rotates;
Cleaning means for cleaning the toner adhered to the belt member in contact with the belt member, the axial length of the support rotator being shorter than the belt member;
Steering means for moving the rotating belt member in the axial direction;
Detecting means for detecting the position of the belt member in the axial direction;
During image formation, the steering unit is controlled based on the detection result of the detection unit, and the cleaning unit contacts the belt member in a first range of the belt member shorter than the belt member in the axial direction. First control means for moving the belt member in the axial direction ,
Based on the detection result of the detection means, the steering means is controlled so that the cleaning means comes into contact with the belt member in a second range of the belt member that is longer than the first range in the axial direction. An image forming apparatus comprising: a second control unit that moves the belt member in the axial direction ;
The second control unit controls the steering unit during non-image formation to rotate the belt member one or more times in a state where one end portion of the second range of the belt member reaches the cleaning blade. A cleaning mode in which the belt member is rotated one or more times in a state in which the belt member is rotated and then the steering means is controlled so that the other end of the second range reaches the cleaning blade. An image forming apparatus. The belt member is an intermediate transfer belt that carries a primary-transferred toner image and superimposes it on a recording material in a secondary transfer portion,
The second control unit controls the steering unit to return one end portion of the second range of the belt member to the cleaning blade in a return operation after jamming of the recording material, and then The image forming apparatus according to claim 1 , wherein a steering unit is controlled so that the other end of the second range reaches the cleaning blade.

Images