JP5146860B2 - Belt device and image forming apparatus - Google Patents

Description

The present invention relates to a belt device and an image forming apparatus including a belt skew detection apparatus for detecting the width direction of displacement of the transfer belt running in a predetermined direction, in particular, a copying machine, a printer, a facsimile, or multifunction machine, and the like thereof BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intermediate transfer belt installed in an image forming apparatus using an electrophotographic method, a belt apparatus provided with a belt deviation detecting device that detects displacement in the width direction of a transfer belt such as a transfer conveyance belt, and an image forming apparatus Is.

2. Description of the Related Art Conventionally, in image forming apparatuses such as copying machines and printers, a tandem type color image forming apparatus provided with an intermediate transfer belt (belt device) is known (for example, see Patent Document 1 and Patent Document 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 amount of displacement of a swinging member (contact) that abuts on the end portion in the width direction of the intermediate transfer belt (endless belt) and swings following the displacement is detected by a detection unit ( (Displacement sensor). Then, based on the detection result of the detection unit, the displacement (meandering) of the intermediate transfer belt is corrected by the correcting means (meandering correction roller).

The conventional image forming apparatus described above may not be able to detect the displacement of the belt member in the width direction with high accuracy.
Specifically, in the conventional device, the swing member (contact) is in surface contact with the belt member, and the contact area with the belt member is large. Therefore, when the belt member is displaced (vibrated) in a direction perpendicular to the width direction (vertical direction that is not the running direction of the belt member), the swinging member swings following the swing in the orthogonal direction. The displacement of the belt member in the width direction could not be detected with high accuracy. Further, the detection result of the displacement in the width direction of the belt member is likely to vary due to variations in the mounting accuracy (mounting angle) of the swing member (contactor) with respect to the belt member. Further, both members are greatly worn due to the sliding contact between the swinging member (contactor) and the belt member for a long time, and an error occurs in the detection result of the width direction displacement of the belt member over time.

Such a problem cannot be ignored particularly in a high-speed machine (an image forming apparatus having a high process line speed) in which a belt member travels at a high speed.
In addition, such a problem is not limited to a belt device using an intermediate transfer belt as a belt member. If the belt device detects and corrects the displacement of the belt member, the transfer conveyance belt is used 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 in order to solve the above-described problems. Even when the speed of the apparatus is increased, the displacement of the transfer belt in the width direction can be reduced with time even with a relatively simple configuration. An object of the present invention is to provide a belt device and an image forming apparatus that can detect with high accuracy.

The belt device according to claim 1 of the present invention travels in a predetermined direction and transfers the toner image carried on the image carrier onto the surface thereof, or conveys the recording medium on the surface. A transfer belt that transfers the toner image carried on the image carrier to the recording medium, and a belt deviation detection device that detects displacement in the width direction of the transfer belt, the belt deviation detection device comprising: An abutting portion that is in contact with the widthwise end portion of the transfer belt and is formed of a metal material and has a circular cross section, and extends from the front surface side to the back surface side of the transfer belt. A central axis that rotatably supports the contact portion, and a position facing the widthwise end of the transfer belt via the central axis, and holds both ends of the central axis in the axial direction. together with the transfer belt one widthwise And the detecting member is displaced the by following be displaced on either side of the side and the other widthwise end side to the displacement with abutment in the width direction, the optical width direction of displacement of the object to be detected member And an optical sensor for detecting.

Further, the belt device according to the second aspect of the present invention that, in the invention according to claim 1, wherein the optical sensor, the is to detect the displacement amount of the detected member.

According to a third aspect of the present invention, in the belt device according to the second aspect, the optical sensor detects a light emitting element that emits light and light incident from the light emitting element. And a light receiving element.

According to a fourth aspect of the present invention, there is provided a belt device that travels in a predetermined direction and transfers a toner image carried on an image carrier onto the surface thereof, or conveys a recording medium on the surface. A transfer belt that transfers the toner image carried on the image carrier to the recording medium, and a belt deviation detection device that detects displacement in the width direction of the transfer belt, and the belt deviation detection device includes: A cylindrical body made of a metal material and in contact with an end in the width direction of the transfer belt, a central axis of the cylindrical body extending from the front surface side to the back surface side of the transfer belt, and the central axis An arm member that holds both ends in the axial direction and swings following the displacement even if the transfer belt is displaced to one of the width direction one end side and the width direction other end side, and the arm member optics for detecting the displacement optically And capacitors, are those provided with the.

Further, according belt device to the fifth aspect of the present invention is the invention according to claim 4, wherein the arm member, the surface of the transfer belt relative to the position where the cylindrical body is brought into contact with the transfer belt The central axis is held by the position on the side and the position on the back side.

According to a sixth aspect of the present invention, in the belt device according to the fourth or fifth aspect, the arm member faces the widthwise end of the transfer belt via the central axis. The central axis is held at a position.

According to a seventh aspect of the present invention, in the belt device according to any of the fourth to sixth aspects, the optical sensor detects a displacement amount of the arm member.

According to an eighth aspect of the present invention, there is provided a belt device that travels in a predetermined direction and transfers a toner image carried on an image carrier onto the surface thereof, or a recording medium on the surface. A transfer belt for transferring the toner image carried on the image carrier to the recording medium while conveying the belt, and a belt deviation detection device for detecting a displacement in the width direction of the transfer belt. The apparatus is formed of a metal material and abuts against a widthwise end of the transfer belt, and a central axis of the cylinder extends from the front side to the back side of the transfer belt, A pair of holding portions that hold the central axis at both ends, a first arm portion that holds the pair of holding portions and extends in a direction parallel to the axial direction of the central axis, and the first arm A second arm portion that swings in conjunction with the portion; As well as comprising a, a swing member which swings said transfer belt to follow its displacement be displaced on either side of the width direction end side and the other widthwise end side, the displacement of the second arm portion And an optical sensor for optical detection.
According to a ninth aspect of the present invention, in the belt device according to the eighth aspect of the present invention, the first arm portion is configured so that the cylindrical body contacts the transfer belt with respect to a position where the cylindrical body contacts the transfer belt. The holding portion is held by the position on the front surface side and the position on the back surface side.
According to a tenth aspect of the present invention, in the belt device according to the eighth or ninth aspect, the first arm portion is disposed at an end in the width direction of the transfer belt via the central axis. The holding part is held at an opposing position.
The belt device according to an eleventh aspect of the present invention is the belt device according to any one of the eighth to tenth aspects, wherein the optical sensor detects a displacement amount of the second arm portion. .
According to a twelfth aspect of the present invention, in the belt device according to the seventh aspect or the eleventh aspect, the optical sensor includes a light emitting element that emits light and an incident light that is emitted from the light emitting element. A light receiving element for detecting light.
According to a thirteenth aspect of the present invention, in the belt device according to any one of the fourth to twelfth aspects, the cylindrical body has a length in the central axis direction that is the thickness of the transfer belt. It is formed to be longer.
According to a fourteenth aspect of the present invention, there is provided the belt device according to any one of the fourth to thirteenth aspects, wherein the cylindrical body is centered on the central axis following the movement of the transfer belt. It is formed to be rotatable.
The belt device according to claim 15 is the belt device according to any one of claims 1 to 14, wherein the transfer belt is formed to have a thickness of 80 to 100 μm. Is.
An image forming apparatus according to a sixteenth aspect of the present invention includes the belt device according to any one of the first to fifteenth aspects, and the image carrier is disposed along a running direction of the transfer belt. And a plurality of image carriers provided to face the surface of the transfer belt.
An image forming apparatus according to a seventeenth aspect of the present invention is the image forming apparatus according to the sixteenth aspect, wherein the plurality of image bearing members are a toner of one of cyan, magenta, yellow, and black. Four image carriers each having an image carried on the surface are formed.
An image forming apparatus according to an eighteenth aspect of the present invention is the image forming apparatus according to the sixteenth or seventeenth aspect, wherein the transfer belt runs in a predetermined direction and is carried on the plurality of image carriers. An intermediate transfer belt stretched by at least a driving roller, a tension roller, a movable roller, and a counter roller, and a secondary transfer member facing the counter roller; A toner image on the intermediate transfer belt is transferred to a recording medium between the opposed rollers, and the movable roller causes a part of the plurality of image carriers to contact the intermediate transfer belt. The intermediate transfer belt is configured to be movable so as to be able to be separated from other image carriers, and the belt misalignment detection device includes a region where the intermediate transfer belt is stretched. In the first region where the intermediate transfer belt is stretched between the drive roller and the counter roller, and the movable roller is arranged in the first region in the region where the intermediate transfer belt is stretched. This is arranged in the second area other than the area.
An image forming apparatus according to a nineteenth aspect of the present invention is the image forming apparatus according to the eighteenth aspect, wherein the plurality of image carriers are disposed above the intermediate transfer belt, and the secondary transfer member Is arranged below the intermediate transfer belt.
An image forming apparatus according to a twentieth aspect of the present invention includes the belt device according to any one of the first to fifteenth aspects, wherein the transfer belt travels in a predetermined direction and the plurality of the belt devices. A toner image respectively carried on an image carrier is transferred to the surface, and is an intermediate transfer belt stretched by at least a driving roller, a tension roller, and a counter roller, and is a secondary belt facing the counter roller. A toner image on the intermediate transfer belt is transferred to a recording medium between a transfer member and the opposing roller, and the belt deviation detecting device is configured to face the driving roller in a region where the intermediate transfer belt is stretched. The intermediate transfer belt is disposed in a first region where the intermediate transfer belt is stretched between the rollers, and the tension roller is disposed in the first region in the region where the intermediate transfer belt is stretched. In which are arranged in a second region other than the region.
An image forming apparatus according to a twenty-first aspect of the present invention includes the belt device according to any one of the first to fifteenth aspects, wherein the transfer belt travels in a predetermined direction and the plurality of the plurality of belt devices. A toner image respectively carried on an image carrier is transferred to the surface, and is an intermediate transfer belt stretched by at least a driving roller, a tension roller, a correction roller, and a counter roller, and is opposed to the counter roller. A toner image on the intermediate transfer belt is transferred to a recording medium between the secondary transfer member and the counter roller, and the correction roller is configured to move in a width direction of the correction roller based on a detection result of the belt shift detection device. The intermediate transfer belt is configured to correct the displacement in the width direction by swinging the other end side with the one end side of the belt as a fulcrum. The intermediate transfer belt is disposed in a first region where the intermediate transfer belt is stretched between the driving roller and the counter roller in a region where the intermediate transfer belt is stretched, and the correction roller is stretched by the intermediate transfer belt. It is arranged in a second region other than the first region among the regions to be laid.
According to a twenty-second aspect of the present invention, in the image forming apparatus according to the twentieth or twenty-first aspect, the image carrier is disposed above the intermediate transfer belt, and the secondary The transfer member is disposed below the intermediate transfer belt.

In the present invention, since the contact portion of the swinging member that contacts the widthwise end of the transfer belt has a curved shape, the swinging member makes line contact with the transfer belt, and the contact area of the contact portion is reduced. can do. As a result, a belt device and an image forming apparatus that can detect the displacement in the width direction of the transfer belt with high accuracy even with lapse of time even when the speed of the apparatus is increased. Can be provided.

1 is an overall configuration diagram illustrating an image forming apparatus according to Embodiment 1 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 belt shift | offset | difference detection apparatus. It is a perspective view which shows the belt deviation detection apparatus in Embodiment 2 of this invention.

  Hereinafter, embodiments 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.

Embodiment 1 FIG.
A first embodiment of the present invention will be described in detail with reference to FIGS.
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 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 developing 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, a counter roller 12B, a tension roller 12C, The correction roller 13, the movable roller 11, the roller member 14 (regulating member), the belt deviation detecting device 80, the photo sensor 90, 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, 12A to 12C, 13, and 14, and is endlessly moved in the direction of the arrow in FIG. 3 by the rotational drive of one roller member (drive roller) 12A. Is done.

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 counter roller 12B sandwiches the intermediate transfer belt 8 with 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, referring to FIGS. 3 to 5, the belt deviation detection device 80 characteristic of the image forming apparatus (intermediate transfer belt device) according to the first embodiment will be described in detail.
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 the belt deviation detection device 80.
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, a counter roller 12B, The tension roller 12C, the correction roller 13 as correction means, the movable roller 11, the roller member 14, the belt deviation detection device 80, the photo sensor 90, the intermediate transfer cleaning unit 10, the abnormality detection sensor 88, and the like.

  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 six roller members (a driving roller 12A, a counter roller 12B, a tension roller 12C, a movable roller 11, a correction roller 13, and a roller member 14).

In the first embodiment, the intermediate transfer belt 8 is made of a single layer or a plurality of layers of PVDF (vinylidene fluoride), ETFE (ethylene-tetrafluoroethylene copolymer), PI (polyimide), PC (polycarbonate), and the like. In this configuration, 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 first 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).
The counter roller 12 </ b> B is in contact with the secondary transfer roller 19 through the intermediate transfer belt 8. The 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 roller members 12B and 12C.

Here, the intermediate transfer belt device 15 according to the first exemplary embodiment is provided with a belt deviation detection device 80 that detects the displacement of the intermediate transfer belt 8 in the width direction (the vertical direction in FIG. 3). .
Specifically, referring to FIG. 5, the belt deviation detection device 80 includes a swinging member 82 that contacts the end portion in the width direction of the intermediate transfer belt 8, and a distance measuring sensor as a detection unit that detects the 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.
The first arm portion 82a is provided with a cylindrical body 82a1 as an abutting portion that abuts against an end portion of the intermediate transfer belt 8 in the width direction. One end of the first arm portion 82a 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)

  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 (detection unit) is mainly composed of a light emitting element (infrared light emitting diode) and a position detecting element (PSD) that are arranged side by side 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.

In the first embodiment, the intermediate transfer belt 8 is set to travel at 400 mm / second in the traveling direction (the direction indicated by the solid line arrow in FIG. 5).
Further, the urging force of the spring 83 is so weak that the intermediate transfer belt 8 is not deformed by the contact force of the swing member 82, and the swing member 82 follows the displacement in the width direction of the intermediate transfer belt 8 without vibration (chattering). It is set to be strong enough. Specifically, in the first embodiment, the contact force of the contact portion (cylindrical body 82a1) of the swing member 82 with respect to the intermediate transfer belt 8 is set to about 70g.

Here, the contact portion of the swing member 82 (first arm portion 82a) is a cylindrical body 82a1, and is formed in a curved surface shape.
As a result, the swinging member 82 makes line contact with the intermediate transfer belt 8 (macroscopically point contact), and the contact area of the contact portion that contacts the intermediate transfer belt 8 can be reduced. . Therefore, even if the intermediate transfer belt 8 swings in the direction perpendicular to the width direction (the direction perpendicular to the paper surface of FIG. 4), the swing member 82 is less likely to swing due to the swing in the orthogonal direction. Even if the mounting accuracy (mounting angle) of the swing member 82 with respect to the intermediate transfer belt 8 varies, the detection result of the distance measuring sensor 81 is less likely to vary. Further, wear due to sliding contact between the swing member 82 (cylindrical body 82a1) and the intermediate transfer belt 8 is reduced. Therefore, the displacement in the width direction of the intermediate transfer belt 8 can be detected with high accuracy over time.

In the first embodiment, the cylindrical body 82a1 as the contact portion is formed of a metal material such as stainless steel. As a result, the cylindrical body 82a1 (contact portion) is not easily worn by sliding contact with the intermediate transfer belt 8, and the problem that the detection accuracy of the distance measuring sensor 81 decreases with time is reduced. In particular, the surface of the cylindrical body 82a1 (contact portion) is preferably smooth and has a low coefficient of friction.
Further, in the first embodiment, the cylindrical body 82a1 (contact portion) is configured to rotate following the traveling of the intermediate transfer belt 8 (traveling in the direction of the solid line arrow in FIG. 5). . Thereby, the wear of the cylindrical body 82a1 due to the contact with the intermediate transfer belt 8 is reduced, and the problem that the detection accuracy of the distance measuring sensor 81 decreases with time is reduced. Since the central axis of the cylindrical body 82a1 is held by the first arm portion 82a, the swinging member 82 does not swing unless the intermediate transfer belt 8 is displaced even if the cylindrical body 82a1 rotates.

Here, a roller member 14 that restricts displacement in a direction different from the width direction and the traveling direction of the intermediate transfer belt 8 is installed in the vicinity of the belt deviation detection device 80. Specifically, the roller member 14 is close to a contact portion (cylindrical body 82a1) between the swing member 82 (first arm portion 82a) and the intermediate transfer belt 8.
With such a configuration, the displacement (shake) of the intermediate transfer belt 8 in the orthogonal direction (in the direction perpendicular to the paper in FIG. 4) in the belt deviation detection device 80 (contact portion 82a1) is reduced. That is, since the belt tension of the intermediate transfer belt 8 is increased by the roller member 14, the displacement of the belt shift detection device 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 detected originally, the belt deviation detection device 80 also detects a displacement component in a direction different from the width direction and the traveling direction. Is reduced. Therefore, the detection accuracy of the intermediate transfer belt 8 with respect to the belt shift by the belt shift detection device 80 is further improved.

When the displacement (displacement amount) of the intermediate transfer belt 8 is detected by the belt deviation detection device 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. The
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 on the inner peripheral surface of the intermediate transfer belt 8. 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 first embodiment, the belt deviation detection device 80 is disposed at a position 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 belt deviation detecting device 80 is disposed on the downstream 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.
In this way, by disposing the belt deviation detecting device 80 at a position away from the correction roller 13, even if rocking (correction operation) is performed by the correction roller 13, the regulating force (on the intermediate transfer belt 8 by the roller member 14 ( The detection accuracy of the belt deviation detecting device 80 is improved without lowering the restraining force of the displacement in the orthogonal direction.

In the intermediate transfer belt device 15 according to the first exemplary embodiment, referring to FIG. 4, the abnormality detection sensor 88 is located at a predetermined distance (about 5 mm) from both ends of the intermediate transfer belt 8 in the width direction. is set up.
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 first exemplary embodiment, the belt deviation detection device 80 is disposed at a position away from the facing region between the intermediate transfer belt 8 and the photosensitive drums 1Y, 1M, 1C, and 1K. ing. Specifically, the belt deviation detection device 80 and the roller member 14 are disposed downstream of the intermediate transfer belt 8 in the running direction (primary transfer) with respect to the opposing area between the intermediate transfer belt 8 and the photosensitive drums 1Y, 1M, 1C, and 1K. It is the position after the process.
As a result, the intermediate transfer belt device 15 can be reduced in size as compared with the case where the belt deviation detecting device 80 is 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. Furthermore, compared to the case where the belt deviation detecting device 80 is disposed in the above-described facing region, the maintenance performance of the belt deviation detecting device 80 is improved and the belt deviation detecting device 80 is disposed in the vicinity of the image forming units 6Y, 6M, 6C, 6K. The malfunction of the belt deviation detecting device 80 (ranging sensor 81) due to noise caused by the high voltage power source (not shown) is suppressed.

In the intermediate transfer belt device 15 according to the first exemplary embodiment, the photo sensor 90 is close to the roller 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 member 14 in this way, the fluctuation 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 first embodiment, the contact portion (cylindrical body 82a1) of the swing member 82 that contacts the end portion in the width direction of the intermediate transfer belt 8 (belt member) has a curved shape. Further, the swinging member 82 is in line contact with the intermediate transfer belt 8 and the contact area of the contact portion is reduced. 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 detected with high accuracy over time with a relatively simple configuration.

Embodiment 2. FIG.
A second embodiment of the present invention will be described in detail with reference to FIG.
FIG. 6 is a perspective view showing the belt deviation detecting device in the second embodiment, and corresponds to FIG. 5 in the first embodiment. The belt deviation detecting device in the second embodiment is different from that in the first embodiment in which the curved surface portion 82a2 is provided as the contact portion, and the cylindrical body 82a1 is provided as the contact portion.

  Similarly to the first embodiment, the belt deviation detection device 80 according to the second embodiment also includes a swing member 82, a distance measuring sensor 81, a spring 83, 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.

Here, in the second embodiment, the first arm portion 82a is integrally formed with a curved surface portion 82a2 as a contact portion that contacts the end portion in the width direction of the intermediate transfer belt 8. That is, the contact portion of the swing member 82 (first arm portion 82a) is a curved surface portion 82a2, and is formed in a curved surface shape.
As a result, also in the second embodiment, the swinging member 82 makes a line contact (macroscopically a point contact) with the intermediate transfer belt 8, and the contact portion that contacts the intermediate transfer belt 8. The contact area is reduced. Therefore, as in the first embodiment, the displacement in the width direction of the intermediate transfer belt 8 can be detected with high accuracy.

  Also in the second embodiment, it is preferable that the curved surface portion 82a2 as the contact portion is made of a metal material or has a low friction coefficient on the surface thereof. As a result, the durability of the swing member 82 is improved, and the problem that the detection accuracy of the distance measuring sensor 81 decreases with time is reduced.

  As described above, also in the second embodiment, since the abutting portion (curved surface portion 82a2) of the oscillating member 82 that abuts the end portion in the width direction of the intermediate transfer belt 8 is curved, The member 82 is in line contact with the intermediate transfer belt 8 and the contact area of the contact portion is reduced. 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 detected with high accuracy over time with a relatively simple configuration.

  In each of the above embodiments, 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 Embodiment 1 and is an endless belt-shaped photosensitive member) as a belt member. Can be applied. Also in these cases, the same effects as those of the above-described embodiments can be obtained by forming the contact portion of the swinging member that contacts the belt member in a curved surface shape.

  Further, the present invention is not limited to each of the above-described embodiments, and within the scope of the technical idea of the present invention, each of the above-described embodiments can be modified as appropriate other than suggested in each of the above-described embodiments. Is clear. In addition, the number, position, shape, and the like of the constituent members are not limited to the above embodiments, and can be set to a number, position, shape, and the like that are suitable for carrying out the present invention.

1Y, 1M, 1C, 1K photosensitive drum (image carrier),
8 Intermediate transfer belt (belt member),
12A-12C, 14 roller member,
13 Correction roller (correction means),
15 Intermediate transfer belt device (belt device),
80 belt slip detection device,
81 Distance sensor (detector),
82 rocking member,
82a first arm portion,
82a1 cylindrical body (contact portion), 82a2 curved surface portion (contact portion),
82b rotation support shaft, 82c second arm part,
83 Spring,
88 Anomaly detection sensor,
100 Image forming apparatus main body (apparatus main body).

JP 2006-343629 A JP 2001-83840 A

Claims (22)

The toner image carried on the image carrier is transferred to the surface by traveling in a predetermined direction, or the toner image carried on the image carrier is conveyed while the recording medium is conveyed on the surface. A transfer belt for transfer to a medium;
A belt deviation detecting device for detecting displacement in the width direction of the transfer belt;
With
The belt deviation detecting device is
Abutting on the widthwise end of the transfer belt , formed of a metal material, and having a circular cross section;
A central axis extending from the front surface side to the back surface side of the transfer belt and rotatably supporting the contact portion;
It is provided at a position facing the widthwise end of the transfer belt via the central axis, holds both ends of the central axis in the axial direction, and the transfer belt is located at one end in the width direction and the other end in the width direction. A detected member that displaces in the width direction together with the abutment portion following the displacement even if it is displaced to either side ,
An optical sensor for detecting the width direction of displacement of the object to be detected member optically,
A belt device comprising: Wherein the optical sensor is a belt device according to claim 1, characterized in that to detect the displacement amount of the detection target member.   The belt device according to claim 2, wherein the optical sensor includes a light emitting element that emits light and a light receiving element that detects incident light emitted from the light emitting element. The toner image carried on the image carrier is transferred to the surface by traveling in a predetermined direction, or the toner image carried on the image carrier is conveyed while the recording medium is conveyed on the surface. A transfer belt for transfer to a medium;
A belt deviation detecting device for detecting displacement in the width direction of the transfer belt;
With
The belt deviation detecting device is
A cylindrical body made of a metal material and in contact with the widthwise end of the transfer belt;
A central axis of the cylindrical body extending from the front surface side to the back surface side of the transfer belt;
An arm member that holds both ends of the central axis in the axial direction and swings following the displacement even if the transfer belt is displaced to one of the width direction one end side and the width direction other end side ;
An optical sensor for detecting the displacement of said arm member optically,
A belt device comprising:   The arm member holds the central axis at a position on the front side and a position on the back side of the transfer belt with respect to a position where the cylindrical body abuts on the transfer belt. 5. The belt device according to 4.   6. The belt device according to claim 4, wherein the arm member holds the central axis at a position opposed to an end portion in the width direction of the transfer belt via the central axis. The belt device according to claim 4, wherein the optical sensor detects a displacement amount of the arm member. The toner image carried on the image carrier is transferred to the surface by traveling in a predetermined direction, or the toner image carried on the image carrier is conveyed while the recording medium is conveyed on the surface. A transfer belt for transfer to a medium;
A belt deviation detecting device for detecting displacement in the width direction of the transfer belt;
With
The belt deviation detecting device is
A cylindrical body made of a metal material and in contact with an end in the width direction of the transfer belt; a central axis of the cylindrical body extending from the front surface side to the back surface side of the transfer belt; and the central axis A pair of holding portions for holding the two at both ends, a first arm portion for holding the pair of holding portions and extending in a direction parallel to the axial direction of the central axis, and interlocking with the first arm portion A swinging second arm portion that swings in accordance with the displacement of the transfer belt even if it is displaced to one of the width direction one end side and the width direction other end side. A moving member;
An optical sensor for detecting the displacement of the second arm portion optically,
A belt device comprising:   The first arm portion holds the holding portion at a position on the front surface side and a position on the back surface side of the transfer belt with respect to a position where the cylindrical body abuts on the transfer belt. The belt device according to claim 8.   10. The belt device according to claim 8, wherein the first arm portion holds the holding portion at a position facing an end portion in the width direction of the transfer belt via the central axis. The belt device according to any one of claims 8 to 10, wherein the optical sensor detects a displacement amount of the second arm portion.   The belt device according to claim 7 or 11, wherein the optical sensor includes a light emitting element that emits light and a light receiving element that detects incident light emitted from the light emitting element. .   The belt device according to any one of claims 4 to 12, wherein the cylindrical body is formed such that a length in a central axis direction thereof is longer than a thickness of the transfer belt.   The belt device according to any one of claims 4 to 13, wherein the cylindrical body is formed to be rotatable about the central axis following the traveling of the transfer belt.   The belt device according to claim 1, wherein the transfer belt is formed to have a thickness of 80 to 100 μm. A belt device according to any one of claims 1 to 15, comprising:
The image forming apparatus, wherein the image carrier is a plurality of image carriers provided to face the surface of the transfer belt along a running direction of the transfer belt.   17. The plurality of image carriers are four image carriers on which one toner image of cyan, magenta, yellow, and black is supported on the surface, respectively. Image forming apparatus. The transfer belt travels in a predetermined direction so that toner images respectively carried on the plurality of image carriers are transferred to the surface and is stretched by at least a driving roller, a tension roller, a movable roller, and a counter roller. Intermediate transfer belt,
A toner image on the intermediate transfer belt is transferred to a recording medium between a secondary transfer member facing the counter roller and the counter roller;
The movable roller is movable so that the intermediate transfer belt can be separated from other image carriers while a part of the plurality of image carriers is in contact with the intermediate transfer belt. Composed of
The belt shift detection device is disposed in a first region where the intermediate transfer belt is stretched between the driving roller and the opposing roller in a region where the intermediate transfer belt is stretched.
18. The image forming apparatus according to claim 16, wherein the movable roller is disposed in a second region other than the first region in a region where the intermediate transfer belt is stretched. . The plurality of image carriers are disposed above the intermediate transfer belt,
The image forming apparatus according to claim 18, wherein the secondary transfer member is disposed below the intermediate transfer belt. A belt device according to any one of claims 1 to 15, comprising:
The transfer belt travels in a predetermined direction so that toner images respectively carried on the plurality of image carriers are transferred onto the surface, and at least an intermediate portion stretched between a driving roller, a tension roller, and a counter roller. A transfer belt,
A toner image on the intermediate transfer belt is transferred to a recording medium between a secondary transfer member facing the counter roller and the counter roller;
The belt shift detection device is disposed in a first region where the intermediate transfer belt is stretched between the driving roller and the opposing roller in a region where the intermediate transfer belt is stretched.
The image forming apparatus, wherein the tension roller is disposed in a second region other than the first region in a region where the intermediate transfer belt is stretched. A belt device according to any one of claims 1 to 15, comprising:
The transfer belt travels in a predetermined direction so that toner images respectively carried on the plurality of image carriers are transferred onto the surface, and is stretched by at least a driving roller, a tension roller, a correction roller, and a counter roller. Intermediate transfer belt,
A toner image on the intermediate transfer belt is transferred to a recording medium between a secondary transfer member facing the counter roller and the counter roller;
The correction roller corrects the displacement in the width direction of the intermediate transfer belt by swinging the other end side with the one end side in the width direction of the correction roller as a fulcrum based on the detection result of the belt deviation detection device. Configured as
The belt shift detection device is disposed in a first region where the intermediate transfer belt is stretched between the driving roller and the opposing roller in a region where the intermediate transfer belt is stretched.
The image forming apparatus, wherein the correction roller is disposed in a second region other than the first region in a region where the intermediate transfer belt is stretched. The image carrier is disposed above the intermediate transfer belt,
The image forming apparatus according to claim 20, wherein the secondary transfer member is disposed below the intermediate transfer belt.

Images