JP4974282B2 - Belt device and image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus using an electrophotographic system such as a copying machine, a printer, a facsimile, or a composite machine thereof, and a belt device installed therein, in particular, an intermediate transfer belt, a transfer conveyance belt, The present invention relates to a belt device and an image forming apparatus for detecting and correcting a displacement in a width direction of a belt member such as a photosensitive belt.

2. Description of the Related Art Conventionally, in image forming apparatuses such as copying machines and printers, a tandem type color image forming apparatus including an intermediate transfer belt (belt apparatus) is known (for example, see Patent Documents 1 and 2).
Specifically, four photosensitive drums (image carriers) are arranged side by side so as to face the intermediate transfer belt (belt member). On these four photosensitive drums, black (black), yellow, magenta, and cyan toner images are formed, respectively. Then, the toner images of the respective colors formed on the respective photoconductive drums are transferred onto the intermediate transfer belt in an overlapping manner. Further, the toner images of a plurality of colors carried on the intermediate transfer belt are transferred onto a recording medium as a color image.

  In such an image forming apparatus, a technique is known in which the displacement in the width direction of the intermediate transfer belt is detected and the displacement in the width direction of the intermediate transfer belt is corrected based on the detection result (for example, Patent Document 1). , See Patent Document 2). Such a technique suppresses problems such as the meandering of the intermediate transfer belt and the trouble that the intermediate transfer belt is damaged by contact with other members after the intermediate transfer belt is greatly displaced (close to the belt) in the width direction. It is aimed at.

  Specifically, in Patent Document 1 and the like, the displacement amount of a swinging member (contactor) that abuts the end portion in the width direction of the intermediate transfer belt (endless belt) and swings following the displacement is determined by the sensor main part. (Displacement sensor). Then, based on the detection result of the sensor main part, the displacement (meandering) of the intermediate transfer belt is corrected by the correcting means (meandering correction roller).

JP 2006-343629 A JP 2001-83840 A

  The conventional image forming apparatus described above accurately detects the displacement of the belt member in the width direction when the belt member is displaced in a direction orthogonal to the width direction (a direction that is not the running direction of the belt member). I could not. That is, in addition to the detection component (which is a detection component in the width direction) that should be originally detected by the detection means that detects the displacement in the width direction of the belt member, the displacement in a direction different from the width direction and the traveling direction. In some cases, components were also detected. For this reason, the displacement correction of the intermediate transfer belt based on the detection result of the detection means has also become low in accuracy.

  This is because the belt member stretched and supported by the plurality of roller members travels while swinging in a direction orthogonal to the width direction. In particular, such a vibration of the belt member in the orthogonal direction becomes remarkable in a high-speed machine (an image forming apparatus having a high process line speed) in which the belt member travels at a high speed.

  Note that such a problem is not limited to a belt device using an intermediate transfer belt as a belt member, and any belt device that detects and corrects the displacement of the belt member may use a transfer conveyance belt as the belt member. This is also common to the belt device and the belt device using the photosensitive belt as the belt member.

  The present invention has been made to solve the above-described problems. Even when the speed of the apparatus is increased, the displacement of the belt member in the width direction can be accurately detected with a relatively simple configuration. An object of the present invention is to provide a belt device and an image forming apparatus that can be used.

According to a first aspect of the present invention, a belt device is stretched around a plurality of roller members, travels in a predetermined traveling direction, and detecting means detects a displacement in the width direction of the belt member. And a regulating member that regulates displacement of the belt member in a direction different from the width direction and the traveling direction in the vicinity of the detection means, and the belt member is respectively carried by a plurality of image carriers. An intermediate transfer belt to which the toner image is transferred, wherein the plurality of roller members are disposed at least downstream of the belt member in the running direction with respect to a region where the belt members and the plurality of image carriers are opposed to each other. The first roller member is installed on the downstream side of the belt member in the running direction with respect to the first roller member, and the belt member is sandwiched between the secondary transfer roller and recording is performed. A second roller member that forms a secondary transfer nip through which the body is conveyed; and a downstream side of the belt member in the running direction of the belt member with respect to the second roller member and an upstream side of the belt member in the running direction of the facing region And a correction roller as a third roller member that corrects displacement in the width direction of the belt member based on the detection result of the detection means, and the detection means and the restriction member include The belt member is disposed downstream of the first roller member in the running direction of the belt member and upstream of the second roller member in the running direction of the belt member .

  The belt device according to a second aspect of the present invention is the belt device according to the first aspect, wherein the detecting means abuts against an end of the belt member in the width direction so as to be displaced in the width direction of the belt member. A swinging member that swings following and a sensor main portion that detects a displacement amount of the swinging member, wherein the regulating member is close to a contact position between the swinging member and the belt member. It has been done.

The belt device according to a third aspect of the present invention is the belt device according to the first or second aspect, wherein the plurality of roller members are downstream of the correction roller in the traveling direction of the belt member. The belt member is provided upstream of the facing region in the running direction of the belt member, and further includes a movable roller as a fourth roller member that separates the belt member from the plurality of image carriers. is there.

A belt device according to a fourth aspect of the present invention is the belt device according to any one of the first to third aspects, wherein the first roller member is a driving roller for driving the belt member. is there.

  According to a fifth aspect of the present invention, in the belt device according to the first to fourth aspects, the position or / and density of the toner image carried on the belt member is detected. Second detection means is provided, and the second detection means is close to the regulating member.

  A belt device according to a sixth aspect of the present invention is the belt device according to any one of the first to fifth aspects, wherein the regulating member is applied to an inner peripheral surface and / or an outer peripheral surface of the belt member. It is a roller-shaped member that comes into contact.

An image forming apparatus according to a seventh aspect of the invention includes the belt device according to any one of the first to sixth aspects.

  In the present invention, a restricting member for restricting displacement in a direction different from the width direction and the running direction of the belt member is provided in the vicinity of the detecting means for detecting the displacement in the width direction of the belt member. As a result, even when the speed of the apparatus is increased, it is possible to provide a belt apparatus and an image forming apparatus that can detect the displacement of the belt member in the width direction with a relatively simple configuration.

Embodiment.
Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the part which is the same or it corresponds, The duplication description is simplified or abbreviate | omitted suitably.

First, the configuration and operation of the entire image forming apparatus will be described with reference to FIGS.
FIG. 1 is a block diagram showing a printer as an image forming apparatus, and FIG. 2 is an enlarged view showing an image forming unit thereof.
As shown in FIG. 1, an intermediate transfer belt device 15 as a belt device is installed in the center of the image forming apparatus main body 100. Further, image forming portions 6Y, 6M, 6C, and 6K corresponding to the respective colors (yellow, magenta, cyan, and black) are arranged in parallel so as to face the intermediate transfer belt 8 (belt member) of the intermediate transfer belt device 15. Yes.

  Referring to FIG. 2, an image forming unit 6Y corresponding to yellow includes a photosensitive drum 1Y serving as an image carrier, a charging unit 4Y disposed around the photosensitive drum 21, a developing unit 5Y, and a cleaning unit 2Y. , And a static elimination unit (not shown). Then, an image forming process (charging process, exposure process, developing process, transfer process, cleaning process) is performed on the photosensitive drum 1Y, and a yellow image is formed on the photosensitive drum 1Y.

  The other three image forming units 6M, 6C, and 6K have substantially the same configuration as that of the image forming unit 6Y corresponding to yellow except that the color of the toner used is different. A corresponding image is formed. Hereinafter, description of the other three image forming units 6M, 6C, and 6K will be omitted as appropriate, and only the image forming unit 6Y corresponding to yellow will be described.

Referring to FIG. 2, the photosensitive drum 1Y is driven to rotate counterclockwise in FIG. 2 by a drive motor (not shown). Then, the surface of the photosensitive drum 1Y is uniformly charged at the position of the charging unit 4Y (a charging process).
Thereafter, the surface of the photosensitive drum 1Y reaches the irradiation position of the laser beam L emitted from the exposure unit 7, and an electrostatic latent image corresponding to yellow is formed by exposure scanning at this position (in the exposure process). is there.).

Thereafter, the surface of the photosensitive drum 1Y reaches a position facing the developing portion 5Y, and the electrostatic latent image is developed at this position to form a yellow toner image (developing process).
Thereafter, the surface of the photosensitive drum 1Y reaches a position facing the intermediate transfer belt 8 (belt member) and the transfer roller 9Y, and the toner image on the photosensitive drum 1Y is transferred onto the intermediate transfer belt 8 at this position. (This is a primary transfer process.) At this time, a small amount of untransferred toner remains on the photosensitive drum 1Y.

Thereafter, the surface of the photosensitive drum 1Y reaches a position facing the cleaning unit 2Y, and untransferred toner remaining on the photosensitive drum 1Y at this position is collected in the cleaning unit 2Y by the cleaning blade 2a (cleaning). Process.)
Finally, the surface of the photosensitive drum 1Y reaches a position facing a neutralization unit (not shown), and the residual potential on the photosensitive drum 1 is removed at this position.
Thus, a series of image forming processes performed on the photosensitive drum 1Y is completed.

The image forming process described above is performed in the other image forming units 6M, 6C, and 6K in the same manner as the yellow image forming unit 6Y. That is, a laser beam L based on image information is irradiated from the exposure unit 7 disposed above the image forming unit onto the photosensitive drums 1M, 1C, and 1K of the image forming units 6M, 6C, and 6K. Is done. Specifically, the exposure unit 7 emits laser light L from a light source, and irradiates the photosensitive drum through a plurality of optical elements while scanning the laser light L with a polygon mirror that is rotationally driven.
Thereafter, the toner images of the respective colors formed on the respective photosensitive drums through the development process are transferred onto the intermediate transfer belt 8 in an overlapping manner. In this way, a color image is formed on the intermediate transfer belt 8.

  Here, referring to FIG. 3, the intermediate transfer belt device 15 (belt device) includes an intermediate transfer belt 8, four transfer rollers 9Y, 9M, 9C, and 9K, a driving roller 12A, tension rollers 12B and 12C, and a correction roller. 13, the movable roller 11, the roller-shaped member 14 (regulating member), the detection unit 80 (detection unit), the photo sensor 90 (second detection unit), the intermediate transfer cleaning unit 10, and the like. The intermediate transfer belt 8 is stretched and supported by a plurality of roller members 11, 12 </ b> A to 12 </ b> C, and 13 is endlessly moved in the direction of the arrow in FIG. 3 by the rotational drive of one roller member (drive roller) 12 </ b> A. .

The four transfer rollers 9Y, 9M, 9C, and 9K sandwich the intermediate transfer belt 8 between the photosensitive drums 1Y, 1M, 1C, and 1K to form a primary transfer nip. Then, a transfer voltage (transfer bias) opposite to the polarity of the toner is applied to the transfer rollers 9Y, 9M, 9C, and 9K.
The intermediate transfer belt 8 travels in the direction of the arrow and sequentially passes through the primary transfer nips of the transfer rollers 9Y, 9M, 9C, and 9K. In this way, the toner images of the respective colors on the photosensitive drums 1Y, 1M, 1C, and 1K are primarily transferred while being superimposed on the intermediate transfer belt 8.

  Thereafter, the intermediate transfer belt 8 on which the toner images of the respective colors are transferred in a superimposed manner reaches a position facing the secondary transfer roller 19. At this position, the tension roller 12B sandwiches the intermediate transfer belt 8 from the secondary transfer roller 19 to form a secondary transfer nip. The four-color toner images formed on the intermediate transfer belt 8 are transferred onto a recording medium P such as transfer paper conveyed to the position of the secondary transfer nip. At this time, untransferred toner that has not been transferred to the recording medium P remains on the intermediate transfer belt 8.

Thereafter, the intermediate transfer belt 8 reaches the position of the intermediate transfer cleaning unit 10. At this position, the untransferred toner on the intermediate transfer belt 8 is removed.
Thus, a series of transfer processes performed on the intermediate transfer belt 8 is completed. The configuration and operation of the intermediate transfer belt device 15 as a belt device will be described in more detail later with reference to FIGS.

Here, referring to FIG. 1, the recording medium P transported to the position of the secondary transfer nip is fed to the paper feeding unit 26 (or laterally fed) disposed below the apparatus main body 100. From the paper section) via the paper feed roller 27, the registration roller pair 28, and the like.
Specifically, a plurality of recording media P such as transfer paper are stored in the paper supply unit 26 in a stacked manner. When the paper feed roller 27 is driven to rotate counterclockwise in FIG. 1, the uppermost recording medium P is fed toward the rollers of the registration roller pair 28.

  The recording medium P transported to the registration roller pair 28 temporarily stops at the position of the roller nip of the registration roller pair 28 whose rotation drive has been stopped. Then, the registration roller pair 28 is rotationally driven in synchronization with the color image on the intermediate transfer belt 8, and the recording medium P is conveyed toward the secondary transfer nip. In this way, a desired color image is transferred onto the recording medium P.

Thereafter, the recording medium P on which the color image is transferred at the position of the secondary transfer nip is conveyed to the position of the fixing unit 20. At this position, the color image transferred on the surface is fixed on the recording medium P by heat and pressure generated by the fixing roller and the pressure roller.
Thereafter, the recording medium P is discharged out of the apparatus by a pair of discharge rollers (not shown). The transferred P discharged from the apparatus by the pair of paper discharge rollers is sequentially stacked on the stack unit as an output image.
Thus, a series of image forming processes in the image forming apparatus is completed.

Next, the configuration and operation of the developing unit in the image forming unit will be described in more detail with reference to FIG.
The developing unit 5Y includes a developing roller 51Y that faces the photosensitive drum 1Y, a doctor blade 52Y that faces the developing roller 51Y, two transport screws 55Y disposed in the developer containing unit, and an opening in the developer containing unit. A toner replenishment path 43Y that communicates with each other via a toner density, a density detection sensor 56Y that detects a toner density in the developer, and the like. The developing roller 51Y includes a magnet fixed inside, a sleeve rotating around the magnet, and the like. In the developer accommodating portion, a two-component developer composed of a carrier and toner is accommodated.

The developing unit 5Y configured as described above operates as follows.
The sleeve of the developing roller 51Y rotates in the direction of the arrow in FIG. The developer carried on the developing roller 51Y by the magnetic field formed by the magnet moves on the developing roller 51Y as the sleeve rotates. Here, the developer in the developing device 5Y is adjusted so that the toner ratio (toner concentration) in the developer is within a predetermined range.
Thereafter, the toner replenished in the developer accommodating portion circulates through the two separated developer accommodating portions while being mixed and stirred together with the developer by the two conveying screws 55Y (movement in the direction perpendicular to the paper surface of FIG. 2). .) The toner in the developer is attracted to the carrier by frictional charging with the carrier, and is carried on the developing roller 51Y together with the carrier by the magnetic force formed on the developing roller 51Y.

  The developer carried on the developing roller 51Y is conveyed in the direction of the arrow in FIG. 2 and reaches the position of the doctor blade 52Y. The developer on the developing roller 51Y is conveyed to a position facing the photosensitive drum 1Y (development area) after the developer amount is made appropriate at this position. The toner is attracted to the latent image formed on the photosensitive drum 1Y by the electric field formed in the development area. Thereafter, the developer remaining on the developing roller 51Y reaches the upper portion of the developer accommodating portion as the sleeve rotates, and is detached from the developing roller 51Y at this position.

Next, an intermediate transfer belt device 15 (belt device) characteristic of the image forming apparatus according to the present embodiment will be described in detail with reference to FIGS.
FIG. 3 is a configuration diagram showing an intermediate transfer belt device 15 as a belt device. FIG. 4 is a schematic view of a part of the intermediate transfer belt device 15 as viewed in the width direction. FIG. 5 is a perspective view showing a part of the intermediate transfer belt device 15.
3 and 4, an intermediate transfer belt device 15 (belt device) includes an intermediate transfer belt 8 as a belt member, four transfer rollers 9Y, 9M, 9C, and 9K, a driving roller 12A (roller member), Tension rollers 12B and 12C (roller members), a correction roller 13 as a correction means, a movable roller 11, a roller-like member 14 as a regulating member, a detection unit 80 as a detection means, a photosensor 90 as a second detection means, an intermediate The transfer cleaning unit 10 and the abnormality detection sensor 88 are configured.

  The intermediate transfer belt 8 as a belt member is disposed so as to face the photosensitive drums 1Y, 1M, 1C, and 1K as four image carriers that respectively carry toner images of respective colors. The intermediate transfer belt 8 is stretched and supported mainly by five roller members (the drive roller 12A, the tension rollers 12B and 12C, the movable roller 11, and the correction roller 13).

In the present embodiment, the intermediate transfer belt 8 includes PVDF (vinylidene fluoride), ETFE (ethylene-tetrafluoroethylene copolymer), PI (polyimide), PC (polycarbonate), etc. in a single layer or multiple layers. A conductive material such as carbon black is dispersed. The intermediate transfer belt 8 is adjusted so that the volume resistivity is in the range of 10 ⁷ to 10 ¹² Ωcm, and the surface resistivity on the back side of the belt is in the range of 10 ⁸ to 10 ¹² Ωcm. The intermediate transfer belt 8 is set to have a thickness in the range of 80 to 100 μm. In the present embodiment, the thickness of the intermediate transfer belt 8 is set to 90 μm.
If necessary, a release layer can be coated on the surface of the intermediate transfer belt 8. At that time, materials used for the coating are ETFE (ethylene-tetrafluoroethylene copolymer), PTFE (polytetrafluoroethylene), PVDF (vinylidene fluoride), PEA (perfluoroalkoxy fluororesin), FEP (four A fluororesin such as fluorinated ethylene-hexafluoropropylene copolymer) or PVF (vinyl fluoride) can be used, but is not limited thereto.
Further, as a method for manufacturing the intermediate transfer belt 8, there are a casting method, a centrifugal molding method, and the like, and a step of polishing the surface is performed as necessary.

  The transfer rollers 9Y, 9M, 9C, and 9K are opposed to the corresponding photosensitive drums 1Y, 1M, 1C, and 1K through the intermediate transfer belt 8, respectively. More specifically, the yellow transfer roller 9Y faces the yellow photosensitive drum 1Y via the intermediate transfer belt 8, and the magenta transfer roller 9M contacts the magenta photosensitive drum 1M via the intermediate transfer belt 8. The cyan transfer roller 9C faces the cyan photosensitive drum 1C via the intermediate transfer belt 8, and the black (black) transfer roller 9K passes through the intermediate transfer belt 8 for black (black). For example).

The movable roller 11 is held by a holding member (not shown) together with the four transfer rollers 9Y, 9M, 9C, and 9K, and separates the intermediate transfer belt 8 from the photosensitive drums 1Y, 1M, 1C, and 1K. It is configured as follows.
Specifically, when the movable roller 11 moves to the position of the broken line in FIG. 3, the four transfer rollers 9Y, 9M, 9C, and 9K also move downward, and the intermediate transfer belt 8 moves to the photosensitive drums 1Y and 1M. 1C and 1K (moving to the position of the broken line). The operation of separating the intermediate transfer belt 8 from the photosensitive drums 1Y, 1M, 1C, and 1K is performed to reduce wear deterioration of the intermediate transfer belt 8, and is performed at the time of non-image formation or the like. It is.

The drive roller 12A is rotationally driven by a drive motor (not shown). As a result, the intermediate transfer belt 8 travels in a predetermined traveling direction (clockwise in FIG. 3).
One tension roller 12B is in contact with the secondary transfer roller 19 via the intermediate transfer belt 8. Another tension roller 12 </ b> C is in contact with the outer peripheral surface of the intermediate transfer belt 8. An intermediate transfer cleaning unit 10 (cleaning blade) is installed between the tension rollers 12B and 12C.

Here, in the intermediate transfer belt device 15 according to the present exemplary embodiment, a detection unit 80 is installed as a detection unit that detects the displacement of the intermediate transfer belt 8 in the width direction (the vertical direction in FIG. 3). Yes.
Specifically, referring to FIG. 5, the detection unit 80 is a swinging member 82 that contacts the end in the width direction of the intermediate transfer belt 8, and a distance measuring sensor as a sensor main part that detects the amount of displacement of the swinging member 82. 81, a spring 83 that urges the swinging member 82 in a direction to contact the intermediate transfer belt 8, and the like.

The swing member 82 includes a first arm portion 82a, a rotation support shaft 82b, a second arm portion 82c, and the like. One end of the first arm portion 82a is in contact with the end portion in the width direction of the intermediate transfer belt 8, and the other end is fixed to the rotation support shaft 82b. The rotation spindle 82b is rotatably supported by a housing (not shown) of the intermediate transfer belt device 15. One end of the second arm portion 82c is fixed to the rotation support shaft 82b. One end of a spring 83 is connected to the center of the second arm portion 82c. The other end of the spring 83 is connected to the housing.
With such a configuration, the swinging member 82 swings following the displacement in the width direction of the intermediate transfer belt 8 (closer to the belt in the direction indicated by the broken line in FIG. 5) (FIG. 5). (It is a swing in the direction of the solid double arrow in the middle.) In the present embodiment, the intermediate transfer belt 8 is set to travel at 400 mm / second in the traveling direction (in the direction of the arrow in FIG. 5).

  A distance measuring sensor 81 is installed above the other end of the second arm portion 82c of the swing member 82 (fixed to the housing). The distance measuring sensor 81 (sensor main part) is mainly composed of a light emitting element (infrared light emitting diode) and a position detecting element (PSD) that are arranged in parallel in the horizontal direction. Infrared light emitted from the light emitting element is reflected by the surface of the second arm portion 82c and enters the position detection element as reflected light. At this time, the incident position of the reflected light incident on the position detecting element changes depending on the distance between the distance measuring sensor 81 and the surface of the second arm portion 82c, and the output value of the light receiving element (ranging sensor 81) is proportional to the change. Changes. Thereby, the amount of displacement in the width direction of the intermediate transfer belt 8 (distance from the surface of the second arm portion 82c) can be detected. Specifically, when the distance detected by the distance measuring sensor 81 is smaller than a predetermined value, the intermediate transfer belt 8 is displaced to the right in FIG. If the detected distance is larger than the predetermined value, the intermediate transfer belt 8 is displaced to the left in FIG. 5 with respect to the target position.

Here, in the vicinity of the detection unit 80 (detection means), a roller-like member 14 is installed as a restriction member that restricts displacement in a direction different from the width direction and the running direction of the intermediate transfer belt 8. Specifically, the roller-like member 14 is close to a contact position between the swing member 82 (first arm portion 82a) and the intermediate transfer belt 8 (the running direction of the intermediate transfer belt 8 with respect to the contact position). Upstream)).
With such a configuration, the detection unit 80 (the contact position between the swinging member 82 and the intermediate transfer belt 8) in the direction perpendicular to the width direction of the intermediate transfer belt 8 (the vertical direction in FIG. 4). Displacement (runout) is reduced. That is, since the belt tension of the intermediate transfer belt 8 is increased by the roller-like member 14, the displacement of the position of the detection unit 80 in the orthogonal direction is restricted. Therefore, in addition to the detection component (which is a detection component in the width direction) that should be originally detected by the detection unit 80, a problem that a displacement component in a direction different from the width direction and the traveling direction is also detected is reduced. Is done. That is, the detection accuracy of the intermediate transfer belt 8 by the detection unit 80 with respect to the belt is improved.
In the present embodiment, a roller-like member that rotates following the travel of the intermediate transfer belt 8 is used as a restricting member that restricts the displacement of the intermediate transfer belt 8 in the orthogonal direction. With this configuration, damage to the inner peripheral surface of the intermediate transfer belt 8 can be reduced.

When the displacement (displacement amount) of the intermediate transfer belt 8 is detected by the detection unit 80, the displacement in the width direction of the intermediate transfer belt 8 is corrected by the correction roller 13 as a correction unit based on the detection result.
Here, referring to FIG. 3, the correction roller 13 is on the upstream side in the running direction of the intermediate transfer belt 8 with respect to the photosensitive drums 1 </ b> Y, 1 </ b> M, 1 </ b> C, and 1 </ b> K, and It arrange | positions so that it may contact | connect. Then, referring to FIG. 4, the correction roller 13 is configured to swing in the X1 and X2 directions around the swing center 13a when a drive cam (not shown) operates at a predetermined angle.
With this configuration, when the intermediate transfer belt 8 is displaced to the right (belt side) in FIG. 4, the correction roller 13 is swung in the X2 direction based on the detection result to correct the displacement of the intermediate transfer belt 8. Is done. On the other hand, when the intermediate transfer belt 8 is displaced to the left side, the correction roller 13 is swung in the X1 direction based on the detection result, so that the displacement of the intermediate transfer belt 8 is corrected. As a result, problems such as the intermediate transfer belt 8 running meandering, and the intermediate transfer belt 8 being greatly displaced in the width direction (close to the belt) and contacting other members to damage the intermediate transfer belt 8 are suppressed. The

Here, in the present embodiment, the detection unit 80 (detection means) and the roller-like member 14 (regulation member) are disposed at positions away from the correction roller 13 (correction means). Specifically, the correction roller 13 is disposed on the upstream side in the running direction of the intermediate transfer belt 8 with respect to a region where the intermediate transfer belt 8 and the photosensitive drums 1Y, 1M, 1C, and 1K are opposed to each other. The detection unit 80 and the roller-shaped member 14 are disposed on the downstream side in the running direction of the intermediate transfer belt 8 with respect to the facing region between the intermediate transfer belt 8 and the photosensitive drums 1Y, 1M, 1C, and 1K.
As described above, by disposing the detection unit 80 and the roller-shaped member 14 at a position away from the correction roller 13, the intermediate transfer belt 8 by the roller-shaped member 14 even if the correction roller 13 swings (correction operation). The detection accuracy of the detection unit 80 is improved without a reduction in the regulation force (restraint force for displacement in the orthogonal direction).

In the intermediate transfer belt device 15 according to the present embodiment, referring to FIG. 4, an abnormality detection sensor 88 is installed at a position away from both ends in the width direction of the intermediate transfer belt 8 by a predetermined distance (about 5 mm). Has been.
Although not shown, the abnormality detection sensor 88 optically detects the arm member that contacts the intermediate transfer belt 8 that is largely shifted from the belt, and the movement of the arm member about the rotation support shaft caused by the contact of the intermediate transfer belt 8. It consists of an optical sensor or the like.
Then, the abnormality detection sensor 88 detects a state in which the intermediate transfer belt 8 is shifted from the belt beyond the range that can be corrected by the correction roller 13. When an abnormality is detected by the abnormality detection sensor 88, the driving of the intermediate transfer belt 8 (drive roller 12A) is forcibly stopped, and a serviceman call display (serviceman) is displayed on the display unit of the apparatus main body 100. It is displayed that repair is required.)

Here, in the intermediate transfer belt device 15 according to the present exemplary embodiment, the detection unit 80 and the roller-shaped member 14 are arranged at positions away from the facing region between the intermediate transfer belt 8 and the photosensitive drums 1Y, 1M, 1C, and 1K. It is installed. More specifically, the detection unit 80 and the roller-shaped member 14 are disposed downstream of the intermediate transfer belt 8 in the running direction (primary transfer process) with respect to the facing region between the intermediate transfer belt 8 and the photosensitive drums 1Y, 1M, 1C, and 1K. This is the rear position).
Thus, the size of the intermediate transfer belt device 15 can be reduced as compared with the case where the detection unit 80 and the roller-shaped member 14 are disposed in the facing region between the intermediate transfer belt 8 and the photosensitive drums 1Y, 1M, 1C, and 1K. In addition, the contact / separation mechanism of the intermediate transfer belt 8 by the movable roller 11 described above is simplified. Further, compared to the case where the detection unit 80 and the roller-shaped member 14 are disposed in the above-described opposed region, the maintenance of the detection unit 80 is improved and the detection unit 80 and the roller-shaped member 14 are arranged in the vicinity of the image forming units 6Y, 6M, 6C, 6K. A malfunction in which the detection unit 80 malfunctions due to noise from a high-voltage power supply (not shown) provided is suppressed.

Further, in the intermediate transfer belt device 15 according to the present exemplary embodiment, a photo sensor 90 as a second detection unit is close to the roller-shaped member 14 with reference to FIGS. 3 and 4. Here, the photo sensor 90 detects the position and density of the toner image (patch pattern) carried on the intermediate transfer belt 8, and optimizes the image forming conditions. Specifically, the position shift of each color toner image (patch pattern) formed on the intermediate transfer belt 8 through the image forming process described above is optically detected by the photosensor 90, and exposure is performed based on the detection result. The exposure timing of the photosensitive drums 1Y, 1M, 1C, and 1K by the unit 7 is adjusted. Further, the density (toner density) of the toner image (patch pattern) formed on the intermediate transfer belt 8 through the above-described image forming process is optically detected by the photosensor 90 and developed based on the detection result. The toner density of the developer stored in the unit 5 is adjusted.
By installing the photo sensor 90 in the vicinity of the roller-like member 14 in this way, the shake of the surface of the intermediate transfer belt 8 detected by the photo sensor 90 is reduced. Therefore, the distance from the toner image detected by the photosensor 90 is stabilized, and the detection accuracy of the photosensor 90 with respect to the position and density of the toner image is improved.

  As described above, in the image forming apparatus configured as in the present embodiment, the intermediate transfer belt 8 (belt member) is positioned in the vicinity of the detection unit 80 (detection unit) that detects the displacement in the width direction. A roller-like member 14 (regulating member) that restricts displacement in a direction different from the width direction and the running direction of the transfer belt 8 is provided. As a result, even when the speed of the apparatus is increased, the displacement in the width direction of the intermediate transfer belt 8 can be accurately detected with a relatively simple configuration.

  In this embodiment, the roller-like member 14 that contacts the inner peripheral surface of the intermediate transfer belt 8 is used as the restricting member. However, a roller-like member that contacts the outer peripheral surface of the intermediate transfer belt 8 is used as the restricting member. Alternatively, a roller-shaped member (a pair of rollers that sandwich the intermediate transfer belt) that contacts the inner and outer peripheral surfaces of the intermediate transfer belt 8 may be used as the regulating member. Even in such a case, since the shake (flapping) of the intermediate transfer belt 8 in the orthogonal direction is restricted in the vicinity of the detection unit 80, the same effect as in the present embodiment can be obtained.

  In the present embodiment, the present invention is applied to a belt device (intermediate transfer belt device 15) using the intermediate transfer belt 8 as a belt member. On the other hand, the present invention is also applied to a belt device using a transfer conveyance belt as a belt member (a belt device that transfers a plurality of color toner images onto a recording medium while conveying the recording medium on the belt member). The invention can be applied. Furthermore, the present invention is also applied to a belt device using a photosensitive belt (which functions as the photosensitive drum in the present embodiment and is an endless belt-shaped photosensitive member) as a belt member. can do. Also in these cases, the same effect as in the present embodiment can be obtained by installing a regulating member that regulates the vibration (flapping) of the belt member in the orthogonal direction in the vicinity of the detecting means.

  Further, the present invention is not limited to the present embodiment, and it is obvious that the present embodiment can be modified as appropriate within the scope of the technical idea of the present invention, other than suggested in the present embodiment. is there. In addition, the number, position, shape, and the like of the constituent members are not limited to the present embodiment, and the number, position, shape, and the like suitable for implementing the present invention can be achieved.

1 is an overall configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a cross-sectional view illustrating an image forming unit in the image forming apparatus of FIG. 1. FIG. 2 is a configuration diagram illustrating a belt device installed in the image forming apparatus of FIG. 1. It is the schematic which looked at a part of belt device in the width direction. It is a perspective view which shows a part of belt apparatus.

Explanation of symbols

1Y, 1M, 1C, 1K photosensitive drum (image carrier),
8 Intermediate transfer belt (belt member),
12A-12C roller member,
13 Correction roller (correction means),
14 Roller member (regulator member),
15 Intermediate transfer belt device (belt device),
80 detector (detector),
81 Distance sensor (sensor main part),
82 rocking member,
83 Spring,
88 Anomaly detection sensor,
90 Photosensor (second detection means),
100 Image forming apparatus main body (apparatus main body).

Claims (7)

A belt member that is stretched around a plurality of roller members and travels in a predetermined traveling direction;
Detecting means for detecting displacement in the width direction of the belt member;
A regulating member that regulates displacement of the belt member in a direction different from the width direction and the traveling direction in proximity to the detection means;
Equipped with a,
The belt member is an intermediate transfer belt onto which toner images carried on a plurality of image carriers are transferred,
The plurality of roller members are at least
A first roller member disposed on the downstream side of the belt member in the running direction with respect to a facing region between the belt member and the plurality of image carriers;
A second transfer nip that is disposed downstream of the first roller member in the running direction of the belt member and forms a secondary transfer nip that sandwiches the belt member between the first transfer member and the recording medium is conveyed. Two roller members;
The belt member is disposed downstream of the second roller member in the traveling direction of the belt member and upstream of the opposed region in the traveling direction of the belt member, and based on a detection result of the detecting unit. A correction roller as a third roller member for correcting displacement in the width direction of the belt member;
Comprising
The detecting means and the regulating member are disposed downstream of the first roller member in the traveling direction of the belt member and upstream of the second roller member in the traveling direction of the belt member. A belt device characterized by. The detecting means is a swinging member that abuts on the widthwise end of the belt member and swings following the widthwise displacement of the belt member, and a sensor main part that detects the amount of displacement of the swinging member. And comprising
The belt device according to claim 1, wherein the regulating member is close to a contact position between the swing member and the belt member. The plurality of roller members are disposed downstream in the traveling direction of the belt member with respect to the correction roller and upstream in the traveling direction of the belt member with respect to the facing region, and the belt member is The belt device according to claim 1, further comprising a movable roller as a fourth roller member that is separated from the plurality of image carriers. The belt device according to claim 1, wherein the first roller member is a driving roller that drives the belt member. Second detection means for detecting the position or / and density of the toner image carried on the belt member;
The belt device according to any one of claims 1 to 4, wherein the second detection means is in proximity to the restriction member.   The belt device according to any one of claims 1 to 5, wherein the regulating member is a roller-shaped member that contacts an inner peripheral surface and / or an outer peripheral surface of the belt member. An image forming apparatus comprising the belt device according to claim 1.

Images