JP5382524B2 - Belt conveying apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a belt conveyance device and an image forming apparatus.

  2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus, an image forming apparatus using an endless belt as an intermediate transfer member that is a transfer medium or a recording sheet that is a transfer medium is known. The belt is stretched around a plurality of rollers and is driven to circulate. At this time, the belt shifts in the direction perpendicular to the belt conveyance direction (main scanning direction) and the stretched area with the belt in the main scanning direction. An inclined belt skew may occur. If the belt is deviated, the belt may come off the roller, or the end of the belt may come into contact with the side plate that supports the shaft portion of the roller. Also, if belt skew occurs in the primary transfer area of the intermediate transfer belt as the intermediate transfer member, or if belt skew occurs in the transfer area of the paper conveyance belt as the conveying means, the intermediate transfer belt, recording paper, etc. Since a shift occurs in the image forming position on the transfer medium, this becomes image distortion. Further, monochrome images of black (hereinafter referred to as K), yellow (hereinafter referred to as Y), magenta (hereinafter referred to as M), and cyan (hereinafter referred to as C) are formed, respectively. In a color image forming apparatus that obtains a color image by superimposing the toner images on a transfer medium, a deviation in image forming position appears as a color deviation between the color toner images. All of these lead to image quality degradation, and some measures must be taken with respect to the belt skewing in order to obtain a high-quality image.

  In Patent Document 1, two of the rollers that stretch the intermediate transfer belt are used as tiltable steering rollers, and the belt conveyance that suppresses belt shift and belt skew by adjusting the tilt of these steering rollers. An apparatus is described. Specifically, based on the detection result of the position detecting means for detecting the position of the belt in the belt width direction, one of the two steering rollers is tilted to correct the deviation of the belt. Further, based on the detection result of the two position detection means arranged at a predetermined interval in the sub-scanning direction in the primary transfer area of the intermediate transfer belt, the belt skew in the primary transfer area of the intermediate transfer belt is detected, Based on the detection result, the other steering roller is tilted to correct the belt skew in the primary transfer region of the intermediate transfer belt.

  In such a belt conveying device that tilts the steering roller to correct the belt shift and the belt skew, when the steering roller is tilted, the tension at the one end in the width direction of the belt differs from the tension at the other end. There was a problem.

Japanese Patent Application Laid-Open No. 2003-228561 describes a belt conveyance device in which a tension roller that applies tension to a belt is provided with a tension correction unit that corrects a tension difference between both ends of the belt caused by the inclination of a steering roller. Specifically, the inclination angle β of the tension roller is obtained from the inclination angle α of the steering roller at the time of correcting the belt deviation, and the inclination of the steering roller is obtained by inclining the tension roller so as to be the inclination angle β. The accompanying tension difference between both ends of the belt is corrected.
Patent Document 3 describes a belt conveying device in which a steering roller has a function of a tension roller.

  However, in a belt conveyance device that tilts one steering roller to correct the skew of the belt and tilts the other steering roller to correct the deviation of the belt, the two steering rollers are tilted. There is a problem that the calculation of the inclination angle of the tension roller that can correct the tension difference is complicated.

  For this reason, the present applicant has provided a load sensor as load detection means on the tension roller, and based on the detection result of the load sensor, corrects a tension difference in the belt width direction when the steering roller is tilted. Developed. This makes it possible to correct the difference in tension between both ends of the belt without performing complicated calculations. However, in the belt transport device under development, there is a case where the tension difference in the belt width direction when the steering roller is tilted cannot be accurately corrected.

This will be specifically described below.
FIG. 1 is a schematic configuration diagram of a belt conveyance device. In this belt conveyance device, a belt 101 is stretched by a driving roller 102, a tension roller 103, and a steering roller 104. In FIG. 1, the belt movement direction (left and right direction in the figure) on the tension surface between the driving roller 102 and the tension roller 103 of the belt 101 is the X axis, and the tension surface between the driving roller 102 and the tension roller 103 of the belt 101. The vertical direction (vertical direction in the figure) is the Y axis, and the belt width direction is the Z axis.

  At both ends of the tension roller 103, there are provided load sensors as load detecting means (not shown). Further, at both ends of the tension roller 103, actuators as tension means (not shown) that apply tension to the belt 101 by pressing the tension roller 103 in the X-axis direction (hereinafter referred to as tension direction) are provided. These actuators (not shown) are controlled by a control unit as tension control means (not shown) based on load sensors provided at both ends of the tension roller 103. Specifically, the output value of each load sensor is constantly monitored, and if the difference between the output value of one load sensor and the output value of the other load sensor is out of the predetermined range, the actuator is driven so that it falls within the predetermined range. To control.

  Further, the tension roller 103 is not shown in the drawing so that the tension roller 103 is tilted in the Y-axis direction by moving one end of the tension roller 103 in the Y-axis direction and rotating the tension roller 103 about the X-axis. The first steering mechanism is provided. That is, the tension roller 103 also has a function as a steering roller.

  The steering roller 104 has a second steering mechanism (not shown) that tilts the steering roller 104 in the Y-axis direction by moving one end of the steering roller 104 in the Y-axis direction and rotating the steering roller 104 about the X-axis. Is provided. Also, a third steering mechanism (not shown) is provided that tilts the steering roller 104 in the X-axis direction by moving the other end of the steering roller 104 in the X-axis direction and rotating the steering roller 104 about the Y-axis. ing. In the following description, the operation of driving the first steering mechanism and tilting the tension roller 103 in the Y-axis direction is referred to as steering operation 1, and the second steering mechanism is driven and tilting the steering roller 104 in the Y-axis direction. The operation to be performed is referred to as steering operation 2, and the operation to drive the third steering mechanism and tilt the steering roller 104 in the X-axis direction is referred to as steering operation 3.

  FIG. 2 is a graph in which the relationship between the inclination angle of the tension roller 103 in the Y-axis direction and the tension difference between both ends of the steering roller 104 during the steering operation 1 is examined. FIG. 3 is a graph in which the relationship between the tilt angle of the steering roller 104 in the Y-axis direction and the tension difference between both ends of the steering roller 104 during the steering operation 2 is examined. FIG. 4 is a graph in which the relationship between the tilt angle of the steering roller 104 in the X-axis direction and the tension difference between both ends of the steering roller 104 during the steering operation 3 is examined. The belt 101 was rotated clockwise in FIG.

  As shown in FIG. 2, when the tension roller 103 is steered, the tension difference in the width direction of the belt 101 can be corrected with high precision. However, as shown in FIGS. In No. 3, the belt width direction tension difference could not be accurately corrected.

Accordingly, the present inventor has examined the reason why the belt width direction tension difference cannot be accurately corrected in the steering operation 2 and the steering operation 3.
FIG. 5 is a graph in which the relationship between the inclination angle of the tension roller 103 in the Y-axis direction and the inclination angle of the tension roller 103 in the tension direction (X-axis direction) during the steering operation 1 is examined. FIG. 6 is a graph in which the relationship between the tilt angle of the steering roller 104 in the Y-axis direction and the tilt angle of the tension roller 103 in the tension direction (X-axis direction) during the steering operation 2 is examined. FIG. 7 is a graph showing the relationship between the tilt angle of the steering roller 104 in the X-axis direction and the tilt angle of the tension roller 103 in the tension direction (X-axis direction) during the steering operation 3. The belt rotation direction + in FIGS. 5 to 7 is when the belt 101 is rotated clockwise in FIG. 1, and the belt rotation direction − is when the belt 101 is rotated counterclockwise in FIG. That is.

  As shown in FIG. 5, in the case of the steering operation 1 in the belt rotation direction +, the tension roller 103 has a small inclination in the tension direction, but as shown in FIGS. 6 and 7, in the case of the steering operation 2 and 3, The tension roller 103 is greatly inclined in the tension direction.

  From this, in the steering operation 2 and the steering operation 3, it is considered that the inclination of the tension roller 103 in the tension direction is larger than necessary as the reason why the belt width direction tension difference cannot be accurately corrected.

  Next, in the steering operation 2 and the steering operation 3, the reason why the tension roller 103 is inclined more than necessary in the tension direction was examined. As a result, the following may be the cause. That is, in order to suppress the tension difference in the width direction of the belt 101 generated by the tilt of the steering roller 104, one end side of the tension roller 103 moves in the tension direction and the tension roller 103 is tilted. As a result, twisting occurs between the steering roller 104 and the tension roller 103 of the belt 101. Due to such twist, the load from the belt 101 applied to the tension roller 103 varies. In the steering operations 2 and 3, since the tension on the higher tension side is increased by the twist generated by the inclination of the tension roller 103, the value of the load sensor is maintained even if the tension roller 103 is inclined to suppress the tension difference. As a result, it is considered that the tension roller 103 is inclined more than necessary.

  As shown in FIG. 2, if the tension roller 103 is also used as the steering roller 104, the belt width direction tension difference can be corrected with high accuracy. However, even if the tension roller 103 has the function of the steering roller 104, the belt tilt Only one of the line and the belt side can be corrected. For this reason, in order to correct both the belt skew and the belt shift, it is necessary to use a roller other than the tension roller as a steering roller. If a tension sensor is provided on the tension roller, the belt tension difference can be corrected accurately. There is a concern that the problem of not being able to occur.

  The present invention has been made in view of the above background, and an object of the present invention is to provide a belt conveyance device and an image forming apparatus that can satisfactorily correct a difference in tension in the belt width direction.

In order to achieve the above object, the invention of claim 1 is directed to an endless belt stretched and conveyed by a plurality of rollers, belt driving means for driving and rotating the endless belt, and any one of the plurality of rollers. Tensioning means that functions as a tension roller that presses the endless belt toward the endless belt to apply tension to the endless belt, a deviation detection means that detects the deviation of the endless belt, and a predetermined stretch region of the endless belt Based on the detection result of the skew detection means and the deviation detection means, one end of one of the plurality of rollers is relative to the other end in a direction perpendicular to the belt width direction. One end of one of the plurality of rollers based on the detection result of the skew correction means and the skew detection means In a belt conveying apparatus comprising a skew correcting means for correcting skew of the endless belt by moving relative to the other end in a direction perpendicular to the belt width direction, the plurality of rollers other than the tension roller A load detecting means for detecting the load from the belt received by one end of the roller and the load from the belt received by the other end, and pressing the one end side of the tension roller of the tension means based on the detection result of the load detecting means And tension control means for controlling the difference between the pressing force for pressing and the pressing force for pressing the other end.
According to a second aspect of the present invention, in the belt conveying apparatus of the first aspect, the tension control means includes a load from a belt received by one end of a roller for detecting the load by the load detecting means, and a belt received by the other end. The tension means is controlled so that the difference from the load falls within a predetermined range.
According to a third aspect of the present invention, in the belt conveying apparatus of the first or second aspect, the roller for detecting the load by the load detecting means includes at least a roller whose one end is moved by the deviation correcting means and the skew correcting means. One end is adjacent to one of the rollers to be moved.
According to a fourth aspect of the present invention, in the belt conveying apparatus according to any one of the first to third aspects, the load from the belt received by one end of another roller and the other end of the roller from which the load detecting means detects the load. A second load detecting means for detecting a load from the belt received by the belt, wherein the tension control means is based on the detection result of the second load detection means and the detection result of the load detection means. The difference between the pressing force for pressing one end of the tension roller and the pressing force for pressing the other end is controlled.
According to a fifth aspect of the present invention, in the belt conveying apparatus of the fourth aspect, the tension control means includes a load from a belt received by one end of a roller for detecting the load by the load detecting means, and a belt received by the other end. So that both the difference between the load and the load from the belt received by one end of the roller whose load is detected by the second load detecting means and the load from the belt received by the other end fall within a predetermined range. The tension means is controlled.
According to a sixth aspect of the present invention, in the belt conveying device of the fourth or fifth aspect, the roller for detecting the load by the second load detecting means is a tension roller.
According to a seventh aspect of the present invention, in the belt conveyance device according to any of the fourth to sixth aspects, the roller for detecting the load by the second load detecting means is adjacent to the tension roller. .
The invention according to claim 8 is the belt conveying apparatus according to any one of claims 4 to 7, wherein the second load detecting means detects at least one of the rollers, and at least one end of which is moved by the deviation correcting means. It is characterized in that one end is adjacent to one of the rollers that is moved by the row correcting means.
According to a ninth aspect of the present invention, in the belt conveying apparatus according to any of the first to eighth aspects, the roller for detecting the load by the load detecting means is a roller other than the driving roller.
The invention according to claim 10 is the belt conveying apparatus according to any one of claims 1 to 9, wherein the load detecting means detects the load relative to the other end in a direction perpendicular to the belt width direction with respect to the other end. It is characterized by being a roller other than the moving roller.
The invention according to claim 11 is characterized in that an endless belt stretched and conveyed by a plurality of rollers, belt driving means for driving and rotating the endless belt, and any one of the plurality of rollers as the endless belt. A tension means for functioning as a tension roller that applies pressure to the endless belt and detects a deviation of the endless belt, and detects a skew of a predetermined stretch region of the endless belt. Based on the detection results of the skew detection means and the deviation detection means, one end of one of the plurality of rollers is moved relative to the other end in a direction perpendicular to the belt width direction, and the endless Based on the detection result of the deviation correction means for correcting the deviation of the belt and the skew detection means, one end of the plurality of rollers is set to the belt width with respect to the other end. An inclination detecting means for detecting an inclination in a direction in which the tension of the tension roller is applied, in a belt conveying apparatus comprising a skew correcting means for correcting the skew of the endless belt by relatively moving in a direction orthogonal to the direction. And a tension control means for controlling the difference between the pressing force for pressing one end side of the tension roller of the tension means and the pressing force for pressing the other end side based on the detection result of the tilt detecting means. It is characterized by this.
The invention according to claim 12 is the belt conveyance device according to claim 11, wherein the tension control means is configured to adjust the tension of the tension means so that the tension roller does not incline more than a predetermined value based on the detection result of the inclination detection means. A difference between a pressing force for pressing one end of the roller and a pressing force for pressing the other end is controlled.
The invention according to claim 13 is the belt conveying device according to claim 11 or 12, wherein any one of the plurality of rollers has a load from a belt received by one end of the roller and a belt received by the other end. A load detecting means for detecting a load; and the tension control means, based on a detection result of the load detecting means and the inclination detecting means, a pressing force for pressing one end side of the tension roller of the tension means; The difference between the pressing force pressing the other end side is controlled.
According to a fourteenth aspect of the present invention, in the belt conveying apparatus according to the thirteenth aspect, the roller for detecting the load by the load detecting means is a tension roller.
Further, the invention of claim 15 is characterized in that, in the belt conveying device of claim 14, the tension roller is arranged at a position where the tension difference in the belt width direction is the largest when correcting the belt shift or the belt skew feeding. It is.
According to a sixteenth aspect of the present invention, in the belt conveying apparatus of the thirteenth aspect, the roller for detecting the load by the load detecting means is a roller other than the driving roller.
According to a seventeenth aspect of the present invention, in the belt conveying apparatus according to the thirteenth and sixteenth aspects, the roller for detecting the load by the load detecting means is adjacent to the tension roller.
The invention according to claim 18 is the belt conveying apparatus according to any one of claims 13 to 17, wherein the load detecting means detects at least one of the rollers, and at least one end thereof is moved by the deviation correcting means, and the skew correction. One end of the roller is moved adjacent to one of the rollers moved by the means.
The invention according to claim 19 is characterized by comprising the belt conveying device according to any one of claims 1 to 18.
According to a twentieth aspect of the present invention, there is provided a belt conveying device that moves an endless belt endlessly while being stretched by a plurality of rollers, a toner image forming unit that forms a toner image on the front surface of the belt, An image forming apparatus comprising a transfer unit that transfers a toner image formed on the front surface to a recording member. The belt conveying device according to claim 1 is used as the belt conveying device. The load detecting means detects the load by using a roller other than the opposing roller that faces the recording member via the belt.

  According to the invention of claim 1, by providing the load detection means on a roller other than the tension roller, the tension difference in the width direction of the belt can be corrected well. In other words, the rollers other than the tension roller do not incline in order to correct the tension difference in the belt width direction unlike the tension roller. For this reason, it can suppress that a load detection means receives the influence of the twist by the inclination of a roller. As a result, the tension difference in the belt width direction can be detected with high accuracy by the load detection means as compared with the case where the tension roller is provided. Thereby, the tension difference in the width direction of the belt can be corrected better than when the load roller is provided with the load detection means.

  According to the invention of claim 11, the difference between the pressing force for pressing one end side of the tension roller of the tension unit and the pressing force for pressing the other end side is controlled based on the detection result of the tilt detecting unit. Since the tension control means is provided, the inclination of the tension roller can be suppressed by controlling as follows. That is, when the inclination detecting means detects that the tension roller is tilted by a predetermined value or more, the tension applied to the side of the tension roller that is tilted in the direction opposite to the tension applying direction is larger than the pressure on the other side. Control the means. By controlling in this way, the side of the tension roller that is inclined in the direction opposite to the direction of tension application moves in the direction of tension application, and the inclination of the tension roller can be kept within a predetermined range. As a result, even if the load detection means is provided on the tension roller, it is possible to prevent the tension roller from tilting more than necessary, and to properly correct the tension difference in the width direction of the belt during belt deviation correction and belt skew correction. can do.

  According to the present invention, the inclination of the tension roller can be suppressed, and belt deviation correction and belt skew correction can be accurately performed.

The schematic block diagram of the belt conveying apparatus used by the analysis test. The graph which investigated the relationship between the inclination angle of the direction of the Y-axis of a tension roller at the time of steering operation 1, and the tension difference of the both ends of a steering roller. The graph which investigated the relationship between the inclination angle of the direction of the Y-axis of a steering roller at the time of steering operation 2, and the tension difference of the both ends of a steering roller. The graph which investigated the relationship between the inclination angle of the direction of the X-axis of a steering roller at the time of steering operation 3, and the tension | tensile_strength difference of the both ends of a steering roller. The graph which investigated the relationship between the inclination angle of the tension roller in the Y-axis direction and the inclination angle of the tension roller in the tension direction during the steering operation 1. The graph which investigated the relationship between the inclination angle of the steering roller in the Y-axis direction and the inclination angle of the tension roller in the tension direction during steering operation 2. The graph which investigated the relationship between the inclination angle of the direction of the X-axis of a steering roller at the time of steering operation 3, and the inclination angle of the tension direction of a tension roller. 1 is a schematic configuration diagram illustrating a configuration example of an image forming apparatus according to a first embodiment. The schematic perspective view which shows a detection line and a detector. FIG. 2 is a schematic perspective view of a transfer unit according to the first embodiment. FIG. 4 is a schematic perspective view of a transfer unit according to a second embodiment.

[Embodiment 1]
Hereinafter, an image forming apparatus according to a first embodiment to which the present invention is applied will be described in detail with reference to the drawings. FIG. 8 is a schematic configuration diagram showing a configuration example of the image forming apparatus according to the present embodiment. In FIG. 8, a transfer unit 20 as a belt conveying device having an intermediate transfer belt 200 supported with a predetermined tension by a driving roller 211, a steering roller 215, a tension roller 214, a secondary transfer counter roller 213, and a driven roller 212 is shown. I have. Further, on the intermediate transfer belt 200, image forming units 1Y, which are toner image forming units corresponding to the respective colors of yellow (Y), magenta (M), cyan (C), and black (K) according to the belt running direction. 1M, 1C, and 1K are arranged in this order. Each of the image forming units 1Y, 1M, 1C, and 1K includes photosensitive drums 10Y, 10M, 10C, and 10K that are rotatably supported by an apparatus main body frame (not shown), and photosensitive drums 10Y, 10M, and 10C, respectively. , 10K have image writing sections 12Y, 12M, 12C, and 12K for exposing and scanning the surface with a laser beam or the like. Further, around each of the photosensitive drums 10Y, 10M, 10C, and 10K, the chargers 11Y, 11M, 11C, and 11K, and the developing devices 13Y, 13M, and 13C are arranged in accordance with the drum rotation direction (counterclockwise direction in the drawing). , 13K, and primary transfer rollers 14Y, 14M, 14C, 14K are arranged in this order.

  The photosensitive drums 10Y, 10M, 10C, and 10K are rotationally driven in the directions of the arrows (counterclockwise in the figure), and the surfaces thereof are uniformly charged by the chargers 11Y, 11M, 11C, and 11K, and then the image writing units 12Y, 12M, 12C and 12K perform exposure scanning according to input image information to form an electrostatic latent image. The yellow developing device 13Y attaches toner to the electrostatic latent image on the photosensitive drum 10Y to develop it as a yellow toner image, and the magenta developing device 13M attaches toner to the electrostatic latent image on the photosensitive drum 10M. Then, the toner is developed as a magenta toner image, the toner is attached to the electrostatic latent image on the photosensitive drum 10C by the cyan developing device 13C, and developed as a cyan toner image, and the electrostatic latent image on the photosensitive drum 10K is developed by the black developing device 13K. The toner is attached to the image and developed as a black toner image. The yellow toner image, the magenta toner image, the cyan toner image, and the black toner image are primarily transferred onto the intermediate transfer belt 200 that contacts the photosensitive drums 10Y, 10M, 10C, and 10K and rotates in the direction of the arrow. The

  At the primary transfer nips for Y, M, C, and K where the photoreceptors 10Y, 10M, 10C, and 10K abut on the intermediate transfer belt 200, primary transfer rollers 14Y, 14M, 14C, and the like disposed inside the belt loop. The intermediate transfer belt 200 is pressed toward the photoreceptors 10Y, 10M, 10C, and 10K by 14K. A primary transfer bias is applied to the primary transfer rollers 14Y, 14M, 14C, and 14K by a power source (not shown). Accordingly, the Y, M, C, and K toner images on the photoreceptors 10Y, 10M, 10C, and 10K are electrostatically moved toward the intermediate transfer belt 200 in the primary transfer nips for Y, M, C, and K. A primary transfer electric field is formed. In the drawing, the front surface of the intermediate transfer belt 200 that sequentially passes through the primary transfer nips for Y, M, C, and K along with the endless movement in the clockwise direction is for Y, M, C, and K. At the primary transfer nip, Y, M, C, and K toner images are sequentially superposed and primarily transferred. By this superimposing primary transfer, a four-color superimposed toner image is formed on the front surface of the intermediate transfer belt 200.

  Below the transfer unit 20 in the figure, there is provided a paper transport unit 30 as a belt transport device that spans an endless paper transport belt 30c and moves endlessly between a drive roller 30a and a secondary transfer roller 30b. Yes. Then, the intermediate transfer belt 200 and the paper transport belt 30c are sandwiched between the secondary transfer roller 30b of itself and the secondary transfer counter roller 213 of the transfer unit 20. As a result, a secondary transfer nip is formed in which the front surface of the intermediate transfer belt 200 and the front surface of the paper transport belt 30c come into contact with each other. A secondary transfer bias is applied to the secondary transfer roller 30b by a power source (not shown). On the other hand, the secondary transfer counter roller 213 of the transfer unit 20 is grounded. Thereby, a secondary transfer electric field is formed in the secondary transfer nip. Note that a secondary transfer bias may be applied to the secondary transfer counter roller 213 to ground the secondary transfer roller 30b.

  A registration roller pair 33 is disposed on the right side of the secondary transfer nip in the drawing. A registration roller sensor (not shown) is disposed near the entrance of the registration nip of the registration roller pair 33. The recording paper P conveyed from the paper supply device (not shown) toward the registration roller pair 33 abuts the leading end against the registration nip of the registration roller pair 33. As a result, the posture of the recording paper P is corrected, and preparations for synchronization with image formation are completed. Thereafter, the registration roller pair 33 sends the recording paper to the secondary transfer nip at a timing at which the recording paper can be synchronized with the four-color toner image on the intermediate transfer belt 200. In the secondary transfer nip, the four-color superimposed toner image on the intermediate transfer belt 200 is batch-transferred onto the recording paper under the influence of the secondary transfer electric field and the nip pressure, and becomes a full-color image combined with the white color of the recording paper P. .

  The recording paper P that has passed through the secondary transfer nip is separated from the intermediate transfer belt 200 and is conveyed to the fixing device 34 along with its endless movement while being held on the front surface of the paper conveyance belt 30c.

  The transfer residual toner that has not been transferred to the recording paper P at the secondary transfer nip adheres to the surface of the intermediate transfer belt 200 that has passed through the secondary transfer nip. This transfer residual toner is scraped and removed by a belt cleaning device (not shown) that contacts the intermediate transfer belt 200.

  The recording paper P transported into the fixing device 34 is sandwiched between fixing nips formed by contact between a fixing roller 34a including a heat source such as a halogen lamp and a pressure roller 34b pressed toward the recording roller P. Then, the full color image is fixed on the surface by pressurization or heating in the fixing nip, and then discharged from the fixing device 34. Thereafter, the paper is discharged out of the apparatus by a pair of paper discharge rollers 35.

  As shown in FIG. 9, a detection line 201 is formed in the vicinity of one end of the intermediate transfer belt 200 over the entire circumference in the transport direction. In addition, as shown in FIG. 8, a belt moving direction is predetermined in a stretching region (hereinafter referred to as a primary transfer region) in which the image forming units 1Y, 1M, 1C, and 1K of the intermediate transfer belt 200 are sequentially arranged. Two detectors 205a and 205b are arranged so as to face the detection line 201 with a gap therebetween. A control unit (not shown) detects the belt shift by sequentially detecting the position of the detection line 201 in the main scanning direction on one of the detectors 205a and 205b. That is, any one of the detectors 205a and 205b and a control unit (not shown) constitute a shift detection means. The control unit (not shown) sequentially calculates the difference between the main scanning direction position of the detection line 201 detected by the detector 205a and the main scanning direction position of the detection line 201 detected by the detector 205a. Detecting belt skew in the primary transfer area. That is, the detectors 205a and 205b and a control unit (not shown) constitute skew detection means.

  In this embodiment, the belt shift and skew are detected by detecting the movement in the belt main scanning direction of the detection line 201 formed on the intermediate transfer belt 200 with high accuracy in advance, as disclosed in JP-A-2000-233843. Compared to a configuration that detects belt deviation and skew by detecting the position of the belt edge, refer to the edge data measured in advance, or store the data that averages the periodic fluctuation of the edge position in the storage means Therefore, it is possible to detect a belt shift and a belt skew detection at a high cost without a waste time with a lower cost configuration.

FIG. 10 is a schematic perspective view of the transfer unit 20 serving as a belt conveyance device.
As shown in the figure, the intermediate transfer belt 200 is stretched over a driving roller 211, a driven roller 212, a steering roller 215, a tension roller 214, and a secondary transfer counter roller 213, and the driving roller 211 is a motor that functions as a belt driving unit. By being rotationally driven by 211a, the vehicle travels in the direction of arrow A in the figure.

  The steering roller 215 corrects the shift and skew generated in the intermediate transfer belt 200, and both ends of the rotating shaft of the steering roller 215 are supported by a pivot bearing (not shown) so as to be swingable in a direction perpendicular to the roller rotating shaft. Yes. Further, one end side of the steering roller 215 is supported by a shift correction actuator 216 serving as a belt shift correction unit so as to be able to reciprocate in a direction perpendicular to the belt surface (in the direction of the arrow in the figure). Further, the other end side of the steering roller 215 is reciprocated in a direction (arrow direction in the figure) orthogonal to the moving direction of the belt surface and one end side of the steering roller 215 by a skew correction actuator 217 which is a belt skew correction means. Supported as possible.

  The control unit (not shown) drives the deviation correction actuator 216 based on the belt deviation detection information detected by the detector 205a (205b), and moves the steering roller 215 so that the belt moves in a direction opposite to the generated belt deviation direction. By tilting the belt, the shift of the belt is corrected, and image distortion and color misregistration can be prevented. Specifically, a control unit (not shown) checks whether the position of the detection line 201 detected by the detector 205a or 205b in the main scanning direction is out of a predetermined range. When the belt is out of the predetermined range, the steering roller is driven based on the belt deviation detection information detected by the detector 205a or the detector 205b, so that the belt moves in a direction opposite to the generated belt deviation direction. Tilt 215. When the detection line 201 reaches the reference position, the shift correction actuator 216 is driven to return the steering roller 215 to the horizontal position. Alternatively, the steering roller 215 may be tilted so that the belt does not approach again in one direction without returning to the horizontal. Specifically, the belt rotation until the detection line 201 deviates from a predetermined range from the reference position is stored, and when the detection line 201 deviates from the predetermined range, the belt is connected based on the belt rotation. Calculate the belt offset force to move in the direction. Then, the inclination angle of the steering roller 215 that generates a deviation force that cancels this deviation force is obtained, and when the detection line 201 returns to the reference position, the inclination obtained by the steering roller 215 without returning the steering roller 215 horizontally. The drive of the shift correction actuator 216 is controlled so as to be inclined at an angle.

  Further, the control unit (not shown) drives the skew feeding correction actuator 217 based on the belt skew detection information calculated from the detection values of the detectors 205a and 205b, and the direction opposite to the generated belt inclination in the primary transfer region. By tilting the steering roller 215 so that the belt is inclined, the belt skew is controlled within a certain range, and image distortion and color misregistration can be prevented. Specifically, a control unit (not shown) checks whether or not the inclination of the detection line 201 calculated from the detectors 205a and 205b is out of a predetermined range. When the belt is out of the predetermined range, the steering roller 215 is driven so that the skew correction actuator 217 is driven based on the belt skew detection information detected by the detectors 205a and 205b, and the generated belt inclination in the primary transfer region is corrected. Is inclined at a predetermined angle. Thus, by tilting the angle of the steering roller 215 by a predetermined angle, the tilt of the primary transfer region returns to the non-tilt state and rotates in the same posture.

  Further, both ends of the tension roller 214 are supported by tension applying actuators 219a and 219b serving as tension means so as to be able to reciprocate in a direction perpendicular to the belt surface (in the direction of the arrow in the figure). The tension applying actuators 219a and 219b are in contact with the bearings, and the tension roller is pressed toward the belt by the tension applying actuators 219a and 219b via the bearings. Thereby, the intermediate transfer belt 200 is given a predetermined tension by the tension roller 214. Further, load sensors 218a and 218b serving as load detecting means are in contact with bearings that rotatably support the rotation shaft of the driven roller 212.

  In the present embodiment, the steering roller 215 is tilted at the time of belt deviation correction or belt skew correction. When the steering roller 215 is tilted, the one end side of the belt is stretched or slackened due to the tilt of the steering roller 215, and a tension difference is generated in the belt width direction. The belt also generates a shifting force due to a difference in tension in the belt width direction. As a result, even if the steering roller 215 is tilted by a predetermined angle due to the influence of the belt shifting force due to the belt tension difference, the shifting may not be corrected or the skew may not be corrected. Therefore, it is necessary to suppress the tension difference in the belt width direction at the time of belt deviation correction or belt skew correction.

  For this reason, in this embodiment, the tension applied to the belt of the tension roller 214 is controlled as follows to suppress the tension difference in the belt width direction. That is, a control unit (not shown) serving as a tension control unit calculates the belt width direction tension difference of the driven roller 212 based on the detection result of the load sensor 218a on one end side and the detection result of the load sensor 218b on the other end side. To do. Next, when the calculated tension difference is out of the predetermined range, the control unit (not shown) causes the belt width direction tension difference of the driven roller 212 to enter the predetermined range based on the calculated tension difference. The tension applying actuators 219a and 219b are controlled. When the tension difference calculated based on the detection values of the load sensors 218a and 218b enters a predetermined range, the driving of the tension applying actuators 219a and 219b is stopped. Thereby, it is possible to suppress the problem of the belt width direction tension change due to the inclination of the steering roller 215.

  In the present embodiment, load sensors 218a and 218b are provided on the driven roller 212, the belt tension applied to the driven roller 212 is detected by the load sensors 218a and 218b, and the tension applied to the belt of the tension roller 214 is controlled. ing. The driven roller 212 does not incline during tension adjustment unlike the tension roller 214, so that the belt load applied to the roller does not fluctuate due to the influence of twisting of the belt due to the inclination of the roller. Therefore, compared with the case where it is provided on the tension roller 214, it is possible to better detect the belt tension difference with the load sensor. As a result, the tension roller 214 can be accurately controlled, and the tension roller 214 can be prevented from being inclined more than necessary. As a result, it is possible to suppress a tension difference at the time of correcting belt deviation and belt skew.

The load sensors 218a and 218b may be provided on the driving roller 211, the secondary transfer counter roller 213, and the steering roller 215, but are most preferably provided on the driven roller 212 for the following reason. This is because when the belt tension applied to the driving roller 211 is detected by a load sensor, the entire driving mechanism including the driving roller 211 and the driving motor 211a is integrated into one unit in order to accurately detect the tension acting from the belt by the load sensor. And the unit must be supported by a load sensor 218. This is because, when a part of the unit including the drive system other than the load sensor 218 is supported by the apparatus, a part of the tension acting on the drive roller 211 from the belt is received by the support portion, and the load sensor 218 accurately This is because the belt tension cannot be detected. Therefore, when the belt tension applied to the driving roller 211 is detected by the load sensor, there is a problem that the configuration becomes complicated and large, and the cost increases.
Further, when the belt tension applied to the secondary transfer counter roller 213 is detected by a load sensor, the recording paper P repeatedly enters and exits the secondary transfer nip during image formation, and thus the influence of this operation is detected by the load sensor 218. There is a problem that accurate detection is difficult because it acts as a variable factor.
Further, since the steering roller 215 is tilted at the time of belt deviation correction or belt skew correction, the detection result of the load sensor may fluctuate due to the influence of this operation.
Therefore, it is desirable that the roller on which the load sensor 218 is disposed is a roller other than the secondary transfer counter roller 213, the driving roller 211, the steering roller 215, and the tension roller.

  Further, by detecting the belt width direction tension difference between the driven roller 212 adjacent to the steering roller 215, it is possible to more accurately detect the belt width direction tension change due to the inclination of the steering roller 215. This is because the influence of the tension change in the belt width direction due to the inclination of the steering roller 215 directly acts on the driven roller 212 without being influenced by other rollers.

  Even if the tension is constant in the belt width direction at a certain roller position, the tension is not always constant in the belt width direction at other roller positions. Therefore, a second load sensor serving as a second load detecting means is provided on a roller other than the driven roller 212, and the tension difference in the belt width direction at the position of the driven roller and the belt width direction at the position of the roller other than the driven roller 212. The tension control may be performed based on the tension difference.

  As the roller provided with the second load sensor, the tension roller 214 is preferable. This is because the tension roller 214 controls the belt tension so that the tension at the position of the driven roller 212 is constant in the belt width direction. Therefore, if the tension difference in the belt width direction at the position of the tension roller 214 is different from the tension difference in the position of the driven roller 212, the tension at the position of the driven roller 212 at the position of the tension roller 214 is Due to the influence of controlling the belt tension so as to be constant, the tension difference at the position of the tension roller 214 may increase. Therefore, the tension roller 214 is provided with a second load sensor, and tension control is performed based on the tension difference in the belt width direction at the position of the driven roller and the tension difference in the belt width direction at the position of the tension roller 214. Thus, the tension difference in the belt width direction at the position of the tension roller 214 caused by controlling the tension of the belt with the tension roller 214 so that the tension at the position of the driven roller 212 is constant in the belt width direction can be suppressed. it can.

As shown in FIG. 10, second load sensors 221a and 221b for detecting the load applied to the tension roller 214 are provided between the tension applying actuators 219a and 219b and the bearing, and both ends of the tension roller 214 are connected to the second load sensor. It is supported by tension applying actuators 219a and 219b via detection sensors 221a and 221b.
The control unit (not shown) calculates the tension difference calculated based on the detection values of the load sensors 218a and 218b of the driven roller 212 and the tension difference calculated based on the detection values of the second load sensors 221a and 221b of the tension roller 214. And whether or not both are within a predetermined range. If either of them falls outside the predetermined range, the tension applying actuators 219a and 219b are controlled so that both are within the predetermined range. As a result, an increase in the tension difference of the driven roller 212 can be suppressed, and an increase in the tension difference at the position of the tension roller 214 can also be suppressed.

  As described above, when the second load sensors 221a and 221b are provided at both ends of the tension roller 214, the values of the second load sensors 221a and 221b may fluctuate due to the influence of the tilting operation of the tension roller 214. Therefore, a load detecting driven roller having the same configuration as the driven roller 212 may be provided between the steering roller 215 and the tension roller 214. Further, by providing a load detection driven roller between the steering roller 215 and the tension roller 214, the influence of the tension change due to the tilting of the steering roller 215 and the tension at the position of the driven roller 212 become constant in the belt width direction. Thus, it can be directly affected by the change in tension caused by tilting the tension roller 214, which is preferable.

[Embodiment 2]
Next, as in the case of Embodiment 1 described above, another embodiment in which the belt conveyance device of the present invention is applied to a transfer unit of an image forming apparatus (hereinafter, this embodiment is referred to as “Embodiment 2”) will be described. To do. Note that the image forming apparatus of the second embodiment basically has the same configuration as that of the first embodiment. For this reason, the basic configuration is the same as that of the first embodiment, and a description thereof will be omitted.

FIG. 11 is a schematic perspective view of a transfer unit 20a which is a belt conveyance device according to the second embodiment.
As shown in the drawing, in Embodiment 2, position sensors 220 for detecting the position of the end of the tension roller are provided at both ends of the tension roller 214 (the position sensor at the left end in the figure is not shown). A control unit (not shown) obtains the inclination of the tension roller 214 based on the detection results of these position sensors 220. That is, the two position sensors 220 and a control unit (not shown) constitute an inclination detection means.

  As in the first embodiment, the control unit (not shown) determines the detection values of the load sensors 218a and 218b when the difference between the detection values of the load sensors 218a and 218b provided at both ends of the driven roller 212 is out of the predetermined range. Tension is controlled so that the difference falls within the reference range. At this time, the two position sensors 220 detect the inclination of the tension roller 214, and when the inclination of the tension roller 214 reaches a threshold value, the tension control is stopped. As a result, the tension roller 214 can be prevented from being tilted more than necessary, and the belt tension difference at the time of correcting the belt shift and the belt skew can be suppressed.

  The threshold value is appropriately determined depending on the inclination angle of the steering roller 215. In the present embodiment, the inclination angle of the steering roller 215 is changed by belt skew correction, so that an optimum threshold value is calculated each time the inclination angle of the steering roller 215 is changed.

  Further, as in the first embodiment, the loads of the driven roller 212 and the tension roller 214 are detected, and the difference between the detection values of the load sensors 218a and 218b of the driven roller 212 and the detection values of the load sensors 221a and 221b of the tension roller 214 are detected. Tension control may be performed so that both the difference and the difference do not fall outside the predetermined range. Thereby, both the tension difference at the position of the driven roller and the tension difference at the position of the tension roller can be corrected.

  Further, only the tension roller 214 may be provided with a load sensor. In the second embodiment, the position sensor 220 is provided so that the tension roller 214 does not tilt more than a predetermined value. Therefore, even if the load sensor receives the influence of the twisting of the belt due to the tilt roller tilting, it tilts more than the threshold value. There is nothing. Further, by providing the load sensors 218a and 218b on the tension roller 214 that controls the tension difference, the control result of the tension difference of the tension roller 214 can be directly detected by the load sensor.

  Further, both ends of the tension roller 214 may be supported by tension applying actuators 219a and 219b via springs, and the tension difference when the steering roller 215 is tilted by the expansion and contraction of the springs may be corrected. In this case, when the position sensor 220 detects that the tension roller 214 is tilted by a predetermined value, the tension applying actuators 219a and 219b are driven so that the tension roller 214 does not tilt further.

  Further, when the tension difference is corrected by a load sensor provided on the tension roller 214 or the expansion and contraction of the spring, the influence of the belt twist when the tension roller 214 is inclined is the direction in which the tension difference at the position of the tension roller 214 decreases. In this case, the tension roller 214 does not tilt the necessary amount, and there is a possibility that the tension difference in the belt width direction due to the tilt of the steering roller 215 cannot be corrected well. Therefore, not only the upper limit value but also the lower limit value of the inclination of the tension roller 214 is set, the position sensor 220 monitors whether the inclination angle of the tension roller 214 is within a predetermined range, and the inclination angle of the tension roller 214 is predetermined. When out of the range, the tension applying actuators 219a and 219b may be driven to control the inclination angle of the tension roller 214 to fall within a predetermined range.

  In addition, when a tension sensor 214 is provided with a load sensor to correct a tension difference or to correct a tension difference by expansion and contraction of a spring, when the steering roller 215 is tilted, the tension difference is not so large. When the tension roller 214 is provided, the tension roller 214 is hardly inclined. Thus, if the tension roller 214 is not easily inclined when the steering roller 215 is inclined, it is difficult for the position sensor 220 to detect with high accuracy whether the inclination of the tension roller 214 is within a predetermined range. For this reason, it is preferable to provide the tension roller 214 at a position where the tension difference becomes maximum when the steering roller 215 is tilted. In this way, by providing the tension roller 214 at a position where the tension difference is maximized, the tension roller 214 is greatly inclined when the steering roller 215 is inclined. As a result, the predetermined range can be expanded, and the position sensor 220 can detect whether the tension roller 214 is within the predetermined range with high sensitivity. Specifically, as shown in FIG. 11, the tension roller 214 is preferably adjacent to the steering roller 215 on the upstream side in the belt movement direction. A difference in tension is likely to occur when the steering roller 215 is tilted on the upstream side in the belt movement direction with respect to the steering roller 215. Therefore, the tension roller 214 is adjacent to the steering roller 215 on the upstream side in the belt movement direction. The position sensor 220 can often detect whether the tension roller 214 is within a predetermined range.

In the above description, the example in which the present invention is applied to a transfer unit in which the intermediate transfer belt 200 is stretched by a plurality of rollers has been described. However, a plurality of paper transport belts 30c carrying the recording paper P on the front surface are provided. The present invention can also be applied to a paper transport unit stretched by a roller.
In the above-described embodiment, the belt skew correction and the belt deviation correction are performed by one steering roller 215. However, the belt skew correction steering roller 215 and the belt deviation correction steering roller 215 are provided. And may be provided respectively.

As described above, according to the transfer unit 20 serving as the belt conveyance device of the first embodiment, the control unit (not illustrated) serving as the tension control unit receives the one end of the driven roller 212 that is a roller other than the tension roller among the plurality of rollers. On the one end side of the tension roller 214 of the tension applying actuators 219a and 219b based on the detection results of the load sensors 218a and 218b as load detecting means for detecting the load from the belt and the load from the belt received by the other end. The difference between the pressure and the pressing force pressing the other end is controlled. Specifically, the tension applying actuators 219a and 219b are controlled so that the difference between the load from the belt received by one end of the driven roller 212 and the load from the belt received by the other end falls within a predetermined range.
Thus, by detecting the load from the belt applied to the rollers other than the tension roller, the load sensor is affected by the twisting of the belt due to the tilt roller tilting as compared with the case where the load sensor is provided on the tension roller. Can be suppressed. As a result, it is possible to suppress the tension difference in the belt width direction better than when the load sensor 218 is provided on the tension roller 214.

  Further, according to the transfer unit 20 of the first embodiment, the driven roller 212 is adjacent to the steering roller, so that the influence of the tension difference due to the inclination of the steering roller is directly affected by the other rollers without being influenced by the other rollers. Works. Thereby, the tension difference due to the inclination of the steering roller can be corrected well.

In addition, according to the transfer unit 20 of the first embodiment, the control unit detects the load from the belt received by one end of another roller different from the driven roller 212 and the load from the belt received by the other end. The tension applying actuators 219a and 219b are controlled based on the detection result of the second load sensor which is the two load detection means and the detection result of the load sensor. Specifically, the difference between the load from the belt received by one end of the driven roller 212 and the load from the belt received by the other end, the load from the belt received by one end of the roller detected by the second load detection means, The tension applying actuators 219a and 219b are controlled so that both of the difference from the load from the belt received by the other end fall within a predetermined range.
Thereby, the tension difference in the belt width direction at the position of the driven roller and the tension difference in the belt width direction at other positions can be within a predetermined range. As a result, it is possible to further suppress the influence of the shifting force due to the tension difference in the belt width direction at the time of belt shift correction or belt skew correction, and it is possible to perform belt shift correction and belt skew correction more accurately. . Further, it is possible to prevent the belt from twisting when correcting the belt deviation or correcting the skew of the belt.

  Further, according to the transfer unit 20 of the first embodiment, the tension roller 214 is used as the roller provided with the second load sensors 221a and 221b, so that the tension difference in the belt width direction at the tension roller position and the driven roller 212 can be reduced. The tension difference in the belt width direction at the position can be suppressed.

  Further, a roller for detecting a load by the second load sensor may be provided adjacent to the tension roller. Even in this case, the influence of the tension roller can be directly received, and the tension difference in the belt width direction at the tension roller position and the tension difference in the belt width direction at the position of the driven roller 212 can be suppressed. .

  Furthermore, the roller provided with the second load sensors 221a and 221b may be adjacent to the steering roller. Thereby, the influence of the tension difference due to the inclination of the steering roller directly acts on the roller provided with the second load sensors 221a and 221b without being influenced by the other rollers. Thereby, the tension difference due to the inclination of the steering roller can be corrected well.

  Further, according to the transfer unit 20 of the first embodiment, it is preferable that the rollers whose load sensors 218a and 218b detect the load are rollers other than the driving roller. In order to accurately detect the load from the belt applied to the drive roller 211 with a load sensor, the entire drive mechanism including the drive roller 211 and the drive motor 211a is integrally formed as one unit, and this unit is loaded. Since it must be supported by the sensors 218a and 218b, there is a problem that the configuration becomes complicated and large, and the cost increases. Therefore, by providing a load sensor on a roller other than the driving roller, it is possible to avoid a complicated configuration, an increase in size, and a cost increase.

  Further, according to the transfer unit 20 of the first embodiment, the rollers whose load sensors 218a and 218b detect the load are rollers (steering rollers) that relatively move from one end to the other in the direction perpendicular to the belt width direction. Etc.), the fluctuation of the detection result of the load sensor due to the inclination can be suppressed.

  Further, according to the transfer unit 20a, which is the belt conveying device of the second embodiment, the inclination detecting means for detecting the inclination of the tension roller 214 in the direction in which the tension is applied (configured by two position sensors 220 and a control unit (not shown)). On the basis of the detection result, a control unit (not shown) serving as a tension control unit that controls the difference between the pressing force for pressing one end of the tension applying actuators 219a and 219b and the pressing force for pressing the other end is provided. . Specifically, the control unit (not shown) controls one end side of the tension roller 214 of the tension applying actuators 219a and 219b so that the tension roller 214 does not tilt more than a predetermined value based on the detection result of the tilt detection means. The difference between the pressing force to be pressed and the pressing force to press the other end side is controlled. As a result, the tension roller 214 does not tilt more than a predetermined value. Thus, the steering roller 215 is tilted to prevent the tension roller from being tilted more than necessary when correcting the belt shift or the belt skew. As a result, the difference in tension in the belt width direction can be satisfactorily suppressed.

  In addition, according to the transfer unit 20a of the second embodiment, a load detection unit that detects, on any one of the plurality of rollers, a load from the belt received by one end of the roller and a load from the belt received by the other end. A load sensor is provided, and the control unit presses one end side of the tension roller of the tension applying actuators 219a and 219b and presses the other end side based on detection results of the load sensor and the position sensor. Controls the difference from the pressing force. Thereby, while being able to correct | amend a tension difference, it can suppress that a tension roller inclines more than necessary.

  Further, according to the transfer unit 20a of the second embodiment, the load sensor detects a load as a tension roller, whereby the tension roller correction result can be directly detected by the load sensor, and the tension control is performed. It can be simplified.

  Further, according to the transfer unit 20a of the second embodiment, the roller whose load sensor detects the load may be adjacent to the tension roller. Even in this case, the result of correction of the tension roller can be directly detected by the load sensor, and the tension control can be simplified.

  Further, according to the transfer unit 20a of the second embodiment, the roller whose load sensor detects the load may be adjacent to the steering roller. Thereby, the influence of the tension difference due to the inclination of the steering roller directly acts on the roller for detecting the load without being influenced by the other rollers. Thereby, the tension difference due to the inclination of the steering roller can be corrected well.

  Further, according to the transfer unit 20a of the second embodiment, when the tension roller is provided with a load sensor, it is preferable that the tension roller is disposed at a position where the tension difference is the largest when the steering roller is inclined. Accordingly, when the steering roller is tilted, the tension roller needs to be largely tilted in order to suppress the tension difference at the position of the tension roller. As a result, the position sensor can detect with high sensitivity whether or not the tension roller has been tilted more than necessary as compared with the case where the tension roller has a small tilt.

  Further, according to the transfer unit 20a of the second embodiment, the configuration is more complicated than the case where the load sensor is provided on the drive roller by using a roller other than the drive roller as the roller that detects the load by the load sensor. , Increase in size and cost can be avoided.

  Further, according to the transfer units of the first and second embodiments, the load sensor detects a load other than the secondary transfer counter roller that is a counter roller that faces the recording member via the belt. Since the load sensor does not detect the influence when the recording paper enters the secondary transfer nip, the tension difference when the steering roller is tilted can be detected well.

20, 20a: transfer unit 30: paper transport unit 200: intermediate transfer belt 201: detection lines 205a, 205b: detector 211: drive roller 212: driven roller 213: secondary transfer counter roller 214: tension roller 215: steering roller 216 : Shift correction actuator 217: Skew correction actuator 218a, 218b: Load sensors 219a, 219b: Tension applying actuator 220: Position sensors 221a, 221b: Second load sensor

Japanese Patent No. 3976924 JP 2001-147601 A JP 2009-25475 A

Claims (20)

An endless belt stretched and conveyed by a plurality of rollers;
Belt driving means for driving and rotating the endless belt;
Tension means for functioning as a tension roller that applies a tension to the endless belt by pressing any one of the plurality of rollers toward the endless belt;
A deviation detecting means for detecting the deviation of the endless belt;
Skew detection means for detecting skew of a predetermined stretch region of the endless belt;
Based on the detection result of the deviation detecting means, one end of one of the plurality of rollers is moved relative to the other end in a direction perpendicular to the belt width direction to correct the deviation of the endless belt. A shift correction means,
Based on the detection result of the skew detection means, one end of one of the plurality of rollers is moved relative to the other end in a direction perpendicular to the belt width direction to skew the endless belt. In a belt conveyance device comprising a skew correction means for correcting
A load detecting means for detecting a load from a belt received by one end of a roller other than the tension roller and a load received by the other end of the plurality of rollers;
A tension control means for controlling a difference between a pressing force for pressing one end of the tension roller of the tension means and a pressing force for pressing the other end side based on a detection result of the load detecting means. Belt conveyor. In the belt conveyance apparatus of Claim 1,
The tension control means adjusts the tension means so that the difference between the load from the belt received by one end of the roller whose load is detected by the load detection means and the load from the belt received by the other end falls within a predetermined range. A belt conveying device that is controlled. In the belt conveyance device according to claim 1 or 2,
A belt in which the load detection means detects a load adjacent to at least one of a roller whose one end is moved by the deviation correction means and a roller whose one end is moved by the skew correction means. Conveying device. In the belt conveyance apparatus in any one of Claims 1 thru | or 3,
The roller for detecting the load by the load detecting means includes a second load detecting means for detecting a load from a belt received by one end of another roller and a load from a belt received by the other end,
The tension control means presses the one end side of the tension roller of the tension means and the other end side based on the detection result of the second load detection means and the detection result of the load detection means. A belt conveying device that controls a difference from a pressing force. In the belt conveyance apparatus of Claim 4,
The tension control means detects the difference between the load from the belt received by one end of the roller for detecting the load by the load detection means and the load from the belt received by the other end, and the second load detection means detects the load. A belt conveying apparatus characterized by controlling the tension means so that both a difference between a load received by one end of the roller and a load received by the other end of the roller are within a predetermined range. In the belt conveyance device according to claim 4 or 5,
The belt conveying device, wherein the roller for detecting the load by the second load detecting means is a tension roller. In the belt conveyance apparatus in any one of Claim 4 thru | or 5,
A belt conveying apparatus characterized in that a roller for detecting a load by the second load detecting means is adjacent to a tension roller. In the belt conveyance apparatus in any one of Claim 4 thru | or 7,
The roller for detecting the load by the second load detecting means is adjacent to at least one of a roller whose one end is moved by the deviation correcting means and a roller whose one end is moved by the skew correcting means. Belt conveyor device. In the belt conveying apparatus in any one of Claims 1 thru | or 8,
The belt conveying device, wherein the roller for detecting the load by the load detecting means is a roller other than the driving roller. In the belt conveyance device in any one of Claims 1 thru / or 9,
The belt conveying apparatus according to claim 1, wherein the roller for detecting the load by the load detecting means is a roller other than a roller that relatively moves in the direction perpendicular to the belt width direction with respect to the other end. An endless belt stretched and conveyed by a plurality of rollers;
Belt driving means for driving and rotating the endless belt;
Tension means for functioning as a tension roller that applies a tension to the endless belt by pressing any one of the plurality of rollers toward the endless belt;
A deviation detecting means for detecting the deviation of the endless belt;
Skew detection means for detecting skew of a predetermined stretch region of the endless belt;
Based on the detection result of the deviation detection means, one end of one of the plurality of rollers is moved relative to the other end in a direction orthogonal to the belt width direction to correct the deviation of the endless belt. Deviation correction means,
Based on the detection result of the skew detection means, one end of the plurality of rollers is moved relative to the other end in a direction perpendicular to the belt width direction to skew the endless belt. In a belt conveyance device comprising a skew correction means for correcting,
An inclination detecting means for detecting an inclination in a direction in which the tension of the tension roller is applied;
A tension control means for controlling a difference between a pressing force for pressing one end side of the tension roller of the tension means and a pressing force for pressing the other end side based on a detection result of the inclination detecting means; A belt conveying device. In the belt conveyance apparatus of Claim 11,
Based on the detection result of the tilt detecting means, the tension control means presses the one end side of the tension roller of the tension means and presses the other end side so that the tension roller does not tilt more than a predetermined value. A belt conveying device that controls a difference from pressure. In the belt conveyance device according to claim 11 or 12,
In any one of the plurality of rollers, provided is a load detection means for detecting a load from the belt received by one end of the roller and a load from the belt received by the other end,
The tension control means is based on a detection result of the load detection means and the inclination detection means, and a difference between a pressing force for pressing one end side of the tension roller of the tension means and a pressing force for pressing the other end side. A belt conveyance device characterized by controlling the belt. In the belt conveyance device of Claim 13,
The belt conveying device, wherein the roller for detecting the load by the load detecting means is a tension roller. In the belt conveyance device of Claim 14,
A belt conveying device, wherein a tension roller is disposed at a position where the difference in tension in the belt width direction is the largest when correcting the belt shift or belt skew. In the belt conveyance device of Claim 13,
A belt conveying apparatus characterized in that a roller other than a driving roller is used as a roller for detecting a load by the load detecting means. In the belt conveyance device according to claim 13 and 16,
A belt conveying device characterized in that a roller for detecting a load by the load detecting means is adjacent to a tension roller. In the belt conveyance device in any one of Claims 13 thru / or 17,
A belt in which the load detection means detects a load adjacent to at least one of a roller whose one end is moved by the deviation correction means and a roller whose one end is moved by the skew correction means. Conveying device.   An image forming apparatus comprising the belt conveyance device according to claim 1. A belt conveying device that moves the endless belt endlessly while being stretched by a plurality of rollers;
Toner image forming means for forming a toner image on the front surface of the belt;
In an image forming apparatus comprising transfer means for transferring a toner image formed on the front surface of the belt to a recording member,
As the belt conveying device, the belt conveying device according to any one of claims 1 to 10 and 13 to 18,
An image forming apparatus, wherein the load detecting means detects a load other than a facing roller facing the recording member via the belt.

Images