JP2011022549A - Belt conveying device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve very accurate detection without being influenced by the shape of a belt end and without making a time lag in belt skew sensing. <P>SOLUTION: The belt conveying device includes an endless belt that is stretched and conveyed by a plurality of rollers, a belt driving means that drives to rotate the endless belt, and a belt skew correction means that corrects displacement in a direction orthogonal to the conveying direction of the endless belt. The belt conveying device includes a tension detection mechanism at a predetermined position in the shaft direction of at least one of the plurality of rollers, and includes a tilt calculation means that calculates the tilt of the endless belt in a belt traveling direction on the basis of a measured value detected by the tension detection mechanism. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a belt conveying device in which an endless belt member is stretched by a plurality of stretching rollers and rotationally drives the belt member, and an image forming apparatus such as a copying machine, a facsimile, and a printer using the belt conveying device. Is.

  2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus, it is known to use an endless belt as an intermediate transfer member that is a transfer medium or as a conveying unit for recording paper that is a transfer medium. Such a belt is stretched around a plurality of rollers and is driven to circulate. At that time, the belt position is displaced in a direction (main scanning direction) perpendicular to the belt conveyance direction. In other cases, a “belt skew (skew)” in which the belt conveyance direction is inclined with respect to the main scanning direction may occur.

  When the belt skew occurs, the image forming position on the transfer medium such as the intermediate transfer member or the recording paper is displaced, and this causes image distortion. Further, in a color image forming apparatus in which a single color image of yellow (Y), magenta (M), cyan (C), and black (Bk) is formed, and these single color images are superimposed on a transfer medium to obtain a color image. In this case, the image forming position shift appears as a color shift between the color toner images. Since these all mean image quality deterioration, it is necessary to take some measures for belt skew in order to obtain a high-quality image.

  Various methods have been proposed to deal with the above problem. For example, Patent Document 1 (Japanese Patent No. 3976924) provides detection means at different positions in the belt traveling direction, and the difference between the detection signals obtained by these detection means. It is proposed that the inclination of the belt is calculated by the above and the inclination is corrected mechanically using a skew correction mechanism.

  Further, Patent Document 2 (Japanese Patent Laid-Open No. 2006-276427) aims to correct image distortion due to belt skew (skew) as in Patent Document 1, but in this prior art, a skew detection means is used. A configuration is described in which image distortion due to belt skew is corrected by changing output image data and exposure timing using image correction means provided in the image forming unit in accordance with the detected skew amount of the belt. ing.

  Further, in Patent Document 3 (Japanese Patent Laid-Open No. 2008-129518), a belt main scanning direction position is detected along with movement in the belt sub-scanning direction using a 2D sensor, and the position in the belt shift direction is feedback-controlled and feedforward-controlled. The belt moving device configuration is noted.

  As a method for detecting the position of the belt, for example, in Patent Documents 1 and 2, a lever (contact) is applied to the belt end (edge) and the displacement is read by a displacement sensor. Although a method of reading a change in the amount of received light through blocking by the end portion is shown, as described in Patent Document 1, “the edge shape of the intermediate transfer belt depends on the belt manufacturing convenience, belt material, etc. Since the relationship is not strictly a straight line, "means for correcting the deviation caused by that is required.

  Patent Document 1 proposes two methods for executing such correction. The first method is to detect the edge positions at the same location in the belt circumferential direction by shifting the detection timing of the belt edge position by the two edge sensors, and to detect the difference between the detected outputs. It is a method to take. In the second method, the detection outputs of the two edge sensors are continuously captured in increments of a predetermined time over one belt rotation (or the number of belt rotations), and then each belt rotation (or the number of belt rotations) is detected. This is a method of obtaining an average value of sensor outputs and taking the difference. Although these methods can remove the influence of the belt edge shape, some problems arise.

  First, in the first method, after the edge position is detected by the first edge sensor, if the belt skew or the belt shift changes, accurate measurement cannot be performed. In addition, since there is a time delay from the detection by the first sensor to the detection by the second sensor, data is not fixed during this time after the start of measurement, and when skew control is further performed. This time becomes a waste time for the control system, and the control performance is deteriorated. In addition, skew sensing requires a plurality of sensors dedicated to detecting the belt shift direction, leading to an increase in cost.

  Patent Document 2 discloses a method of using a steering roller control signal as a first method of detecting a belt skew. However, this method corrects the belt shift by adjusting the inclination of the roller so that each part on the belt always passes through the same position after one round. Whether skew occurs is determined by the inclination state of each roller, and the belt skew on the image transfer surface that affects image distortion and color misregistration is not determined only by the steering roller inclination. Therefore, if the belt state changes due to temperature fluctuations or fluctuations over time, or if the rollers other than the steering roller are tilted, the steering roller control signal cannot accurately detect the belt skew, and the correction is accurate. Is impossible.

  On the other hand, in Patent Document 2, as a second method, an image position detection mark is formed in a non-image area located between the image areas of the intermediate transfer belt, and belt skew is detected by the mark detection means. The method is shown. In this method, in order to form an image position detection mark, the mark latent image formed on the image carrier must be developed with toner and transferred onto the intermediate transfer belt. There is a problem in that the amount of toner is consumed and the image forming cost increases. In addition, a normal image is transferred from the intermediate transfer belt to a recording paper such as paper. On the other hand, the image position detection mark must be removed by a cleaning member without being transferred. Increases, which causes a cleaning failure.

  In view of the above problems, an object of the present invention is to make it possible to perform highly accurate detection without being affected by the belt end shape and without time delay in belt skew sensing. Provided is an image forming apparatus capable of performing high-quality image output without color misregistration by performing belt skew correction or image correction in the image forming apparatus by performing highly accurate skew detection. Moreover, the problem of cost increase due to the use of a plurality of dedicated sensors is also solved.

  According to the present invention, an endless belt that is stretched and conveyed by a plurality of rollers, belt driving means that drives and rotates the endless belt, and belt deviation correction that corrects displacement in a direction orthogonal to the conveying direction of the endless belt. A tension detecting mechanism is provided at a predetermined position in the axial direction of at least one of the plurality of rollers, and the belt traveling direction is determined based on the measured value detected by the tension detecting mechanism. By providing an inclination calculating means for calculating the inclination of the endless belt at, the above problem can be solved.

  As the tension detection mechanism, pressure sensors arranged at both ends of the roller to which the tension detection mechanism is to be attached are used to calculate the inclination of the endless belt based on the difference in tension tension values detected by both pressure sensors. It is preferable to do this. Further, the displacement sensor disposed at both ends of the roller to which the tension detection mechanism is to be attached is used as the tension detection mechanism, and the inclination of the endless belt can be calculated based on the difference between the measurement values detected by both displacement sensors. Good. Alternatively, as the tension detection mechanism, an inclination sensor arranged at one end of a roller to which the tension detection mechanism is to be attached may be used, and the inclination of the roller detected by the inclination sensor may be the inclination of the endless belt.

  At least one of the plurality of rollers that stretch and convey the endless belt is configured to be tiltable, and the tilt of the endless belt is corrected by tilting the roller based on the tilt data of the belt by the tilt calculating means. However, it is suitable for the purpose.

  Alternatively, a latent image forming unit that forms a latent image on the image carrier based on image data, a developing unit that visualizes the latent image formed on the latent image forming unit, and an image carrier An intermediate transfer member that primarily transfers a visible image formed on the body, and a secondary transfer unit that transfers a transfer image on the intermediate transfer member to a recording sheet, and is formed on a plurality of image carriers. In an image forming apparatus that forms a color image by sequentially transferring a visible image onto an intermediate transfer member, the intermediate transfer member is driven and rotated by an endless belt that is stretched and conveyed by a plurality of rollers. A belt conveying device comprising belt driving means and belt deviation correcting means for correcting displacement in a direction orthogonal to the conveying direction of the endless belt, wherein at least one of the plurality of rollers is a predetermined one in the axial direction. Position, tension detector And a belt conveying device provided with an inclination calculating means for calculating the inclination of the endless belt in the belt traveling direction based on the measurement value detected by the tension detection mechanism, the belt of the belt by the inclination calculating means It is also suitable for the purpose to correct the latent image forming position on the image carrier in the image forming unit based on the tilt data.

  According to the invention according to claim 1, as in the prior art, it is possible to prevent "time delay" that occurs when skew control is performed using a plurality of sensors provided along the belt conveyance direction, The belt can be driven at high speed, and the belt skew can be detected without increasing the number of sensors dedicated to detecting the belt shift direction. Therefore, it is possible to realize a belt conveyance device capable of reducing the cost.

  If pressure sensors and displacement sensors arranged at both ends of the roller are used as tension detection mechanisms and the tension tension and displacement value are detected by the respective sensors, the belt skew can be detected with a simple configuration. Use of an inclination sensor disposed at one end of the roller to which the tension detection mechanism is to be attached is advantageous in terms of cost.

  Correcting the endless belt tilt by tilting at least one of the rollers that stretch and transport the endless belt based on the tilt data of the belt calculated by the tilt calculation means, ensures belt skew with a simple configuration. It becomes possible to correct, and it is possible to prevent positional deviation in the direction orthogonal to the belt conveying direction with a low-cost configuration. In the following embodiment, the tension roller is tilted, but another tension roller can be tilted.

  If the belt transfer device according to the present invention constitutes an intermediate transfer member, and the latent image formation position on the image carrier in the image forming unit is corrected based on the belt inclination data by the inclination calculating means, the belt skew information is obtained. Correctly correcting the image forming position based on this can prevent image distortion and color misregistration due to misalignment in the main scanning direction, and it is not necessary to transfer the image position detection mark onto the belt, which causes belt cleaning failure. Therefore, an image forming apparatus capable of significantly improving the image quality of an output image can be realized.

1 is a diagram illustrating a configuration outline of an image forming apparatus according to the present invention. It is a fragmentary perspective view which shows an example of a belt shift | offset | difference detection means. It is a conceptual diagram explaining a belt deviation adjusting means. It is a figure explaining the color shift for the belt skew at the time of correct | amending in the state without a belt shift. It is a figure which shows the tension detection mechanism attached to a tension roller. It is a figure which shows another tension detection mechanism attached to a tension roller. It is a graph which shows the relationship between the surface pressure difference (stretch tension difference) applied to a tension roller, and a belt inclination. It is a schematic diagram of the composition which attaches a pressure sensor to a belt conveyance device, and calculates belt inclination. It is an outline figure of composition which attaches an inclination sensor to a belt conveyance device, and calculates belt inclination. It is a conceptual diagram which shows the structure which compensates the latent image formation on an image carrier according to a belt inclination.

(Description of color image forming apparatus)
FIG. 1 is a schematic diagram showing the main configuration of an image forming apparatus to which the present invention is applied. This image forming apparatus is of a type in which a plurality of image carriers are arranged in tandem to form a full color image on an intermediate transfer member.

  In order of image formation over time, a yellow image forming unit, a magenta image forming unit, a cyan image forming unit, and a black image forming unit are arranged. In image formation, four image carriers (hereinafter referred to as “photosensitive drums”) 101, 102, 103, 104 are rotationally driven in the directions of arrows (counterclockwise), and the respective surfaces are charged by chargers 111, 112, 113, 114. Then, the exposure devices 121, 122, 123, and 124 perform exposure according to the input image information to form an electrostatic latent image on the photosensitive drum. The yellow developing unit 131 attaches toner to the electrostatic latent image on the photosensitive drum 101 to develop it as a yellow toner image, and the magenta developing unit 132 attaches toner to the electrostatic latent image on the photosensitive drum 102. Then, the toner is developed as a magenta toner image, and the cyan developing unit 133 attaches the toner to the electrostatic latent image on the photosensitive drum 103 to develop it as a cyan toner image, and the black developing unit 134 develops the toner image on the photosensitive drum 104. A toner is attached to the electrostatic latent image and developed as a black toner image. These yellow toner image, magenta toner image, cyan toner image, and black toner image are in contact with the photosensitive drums 101, 102, 103, and 104, and are primarily transferred onto the intermediate transfer belt 200 that rotates in the direction of the arrow. The toner image is transferred and superimposed as a four-color toner image on the intermediate transfer belt 200. These four color toner images are secondarily transferred to a recording paper P conveyed from a paper supply cassette (not shown), thereby obtaining a full color image.

(Belt transfer device / steering belt adjustment)
An outline of the belt deviation detecting means in the image forming apparatus configured as described above is illustrated in FIG. A detection line 201 as a detection mark is formed on the surface of the intermediate transfer belt 200 at a predetermined position near the end in the main scanning direction over the entire circumference in the transport direction. A belt deviation detecting means 205 is arranged at a position facing the detection line, and the position of the detection line 201 in the main scanning direction can be detected. The belt main scanning direction displacement can be detected by sequentially detecting the detection position of the detection line in the main scanning direction.

  FIG. 3 shows the belt deviation adjusting means. The intermediate transfer belt 200 is stretched by a plurality of rollers arranged in parallel, and is driven in the belt conveyance direction by a driving roller 211 among these rollers. While the driving roller 211 and the driven rollers 212 and 213 are fixed at predetermined positions, both ends of the rotating shaft of the tension roller 214 contacting the intermediate transfer belt 200 from the outer periphery of the belt are urged in the direction of the arrow. The intermediate transfer belt 200 is stretched with a substantially constant tension. Further, the remaining steering roller 215 disposed on the inner periphery of the intermediate transfer belt 200 is a member that corrects a shift generated in the intermediate transfer belt 200, that is, a displacement in the main scanning direction (shift correction unit). One end side is supported by a pivot bearing or the like so as to be swingable in the direction orthogonal to the roller rotation axis, and the other end side is supported by an actuator 216 serving as a belt shift correction driving means so as to be able to reciprocate in the arrow direction.

  Based on the information from the belt deviation detecting means 205 (205a, 205b), the actuator 216 is driven to swing the steering roller 215 so that the intermediate transfer belt moves in the direction opposite to the generated displacement in the belt main scanning direction. Thereby, the belt shift is controlled within a certain range, and the belt shift can be suppressed without providing a shift guide member or the like.

  FIG. 4 shows a state of belt conveyance corrected to a state where there is no belt deviation. In FIG. 4, the intermediate transfer belt 200 is conveyed in a direction inclined to the skew angle θ on the image transfer surface due to the influence of the inclination of each roller that conveys the intermediate transfer belt 200, particularly the inclination of the steering roller that eliminates the belt deviation. Yes. For this reason, the image formed on the image transfer surface is inclined at a skew angle θ with respect to the belt conveyance direction, and the transfer position on the intermediate transfer belt of the image formed by each image carrier is shifted in the main scanning direction. appear. That is, image distortion or color misregistration in a color image occurs.

(Skew detection method)
When correcting the deviation of the belt by the steering method as described above, the posture of the belt may be inclined by a certain angle with respect to the original belt conveying direction. In order to eliminate the belt inclination (belt skew), In the example, control is performed based on the tension applied to the belt stretching roller.

  An example of a tension detection mechanism attached to the tension roller 214 will be described with reference to FIG. In the tension roller 214, tension is applied by a spring 217. For example, the direction is limited by a slider mechanism 218, and the size is detected by using a pressure sensor 219 such as a load cell. (Fig. 5a). Further, as an example in which the pressure sensor 219 such as a load cell is not used, as shown in FIG. 5B, for example, a displacement sensor 220 is attached to a predetermined position of the slider mechanism 218, the spring displacement is detected by the displacement sensor, A configuration for calculating the size can be assumed.

  By providing the mechanisms shown in FIG. 5 at both ends in the longitudinal direction of the tension roller 214, it is possible to detect the tension difference between the two ends of the roller. When the skew detection mechanism is installed at a position other than the end, a discontinuous portion of the roller area is provided in the longitudinal direction of the roller, and the discontinuous portion is set as a tension mechanism installation position. That is, the tension roller is divided into a plurality of parts in the longitudinal direction, and the tension mechanism is installed in the core part that is not the rubber roller part.

  FIG. 6 is a plan view showing another example of the tension detection mechanism. In this case, the tension detection mechanism uses a roller tilt sensor. An inclination sensor 221 is provided at one end of the tension roller 214, and the inclination of the roller is measured by the inclination sensor 221, thereby detecting the belt skew. Without providing a tension detection mechanism at both ends of the roller, belt skew can be detected with a simple configuration using a single sensor, and an increase in cost can be suppressed.

  The belt skew changes due to disturbance applied to the belt. The disturbance applied to the belt includes paper, image density and the like in the image forming apparatus in addition to environmental fluctuations such as temperature and humidity. Further, by swinging the steering roller 215 as the deviation correction means, the tension state of the belt is also unbalanced between the front side and the back side (front and back in the longitudinal direction of the roller) of the belt conveying device. When the tension state of the belt becomes unbalanced, belt skew occurs, and in the tension roller that works to maintain the tension state of the belt, the difference in applied force becomes the tension difference between both ends or the tension roller inclination. appear. FIG. 7 shows the relationship between the surface pressure difference applied to the tension roller 214, that is, the tension difference and the belt inclination. This relationship also applies to the relationship between tension difference, tension roller inclination and belt skew. The skew of the endless belt has a correlation with the surface pressure difference applied to the tension roller and the roller inclination, and can be estimated by the tension difference in the tension roller or the roller inclination. In this example, the control is performed based on the tension applied to the belt stretching roller. However, the relationship between the tension difference at both ends of the roller and the belt skew is not limited to the tension roller but also applies to other specific rollers, and is stronger. Since the correlation is shown, the belt skew can be calculated from the tension difference with higher accuracy when using the pressure detecting means. Here, for example, when the driving roller 211 is used, it is necessary to support it integrally including a driving system such as a motor, and there is a problem that causes an increase in size and cost of the apparatus. It is desirable to control with. Further, for example, when the steering roller 215 of the belt deviation correcting means is used, there is a tension variation due to the steering operation, so that control other than the steering roller is desirable from the viewpoint of accurate detection. Further, when the roller 213 which is often used as a secondary transfer roller located at the lower part of the apparatus is used, it can be said that other rollers are desirable because tension fluctuation occurs due to the entry of a recording sheet or the like into the secondary transfer unit.

(Skew correction method)
Next, how to correct this according to the skew amount derived from the tension difference will be described. FIG. 8 shows a schematic diagram of the belt conveyance device. In FIG. 8, both the flat surface portion and the side surface portion are shown for the belt portion so that the position of the pressure sensor of the tension detection mechanism in the intermediate transfer belt can be easily recognized, and the drive motor, the speed reducer, and the like are omitted.

  Signals detected by the pressure sensors 219 disposed at both ends in the longitudinal direction of the tension roller 214 are converted into pressure signals by the respective pressure calculation means. The pressure signals 1 and 2 are sent to the difference calculation unit, where the pressure difference is calculated. The pressure difference signal output from the difference calculation unit is sent to the inclination calculating means, where the belt inclination (skew) is calculated.

  The calculated belt inclination can be mechanically corrected by, for example, attaching the same mechanical mechanism to the tension roller 214 in the same manner as the deviation adjusting means of the steering roller 215 in the belt conveying device of FIG.

  An example in the case of using an inclination sensor is shown in FIG. A signal detected by an inclination sensor 221 disposed at one end in the longitudinal direction of the tension roller 214 is sent to a skew calculating unit, where a belt skew is calculated.

  The system for correcting the image forming position on the intermediate transfer belt in the main scanning direction according to the change in the angle of the belt skew is output by the image forming means in order to correct image distortion due to the belt inclination in addition to the mechanical configuration described above. It is assumed that the image is corrected or the exposure timing is adjusted by the exposure controller. This example will be described below.

  In order to correct the image forming position in the main scanning direction on the intermediate transfer belt in accordance with the change in the angle of the belt skew, an optical axis angle changing means is provided in the optical path of the exposure apparatus that forms a latent image on the photosensitive drum. Thus, a method of changing the latent image forming position on the photosensitive drum can be considered. FIG. 10 shows the latent image forming position correcting means.

  In FIG. 10, the image signal transferred from the printer driver unit 601 is input to the image signal generation unit 603 constituting the image writing control unit 602. Engine control information from the engine control unit 604 is also input to the image writing control unit 602 (the image signal generation unit 603 and the writing position control unit 607). In the image signal generation unit 603, the input image signal is subjected to image processing by processing according to engine control information. At this time, the image signal generation unit 603 performs processing using a pixel clock signal (wclk) that defines the minimum pixel used for image formation in order to actually develop an image on a recording sheet. This pixel clock signal is generated as a clock signal (wclk) having a predetermined frequency based on information such as the resolution and the photosensitive drum linear speed from the engine control unit 604 in the pixel clock generation unit 605, and the image signal generation unit 603 and the multiplication are performed. Input to the circuit unit 606. The actual image signal subjected to image processing by the image signal generation unit 603 is input to the writing position control unit 607. The writing position control unit 607 includes a synchronization detection signal (DETP) from the synchronization detection unit 609 of the exposure apparatus (laser writing unit) 608, a belt displacement signal (Δa) generated from the intermediate transfer belt skew information, an engine Engine control information from the control unit 604 is input. The synchronization detection signal (DETP) is a signal for keeping the writing start position in the main scanning direction constant when the laser beam is exposed on the photosensitive drum. This signal is an output signal from the synchronous detection plate arranged outside the scanning region on the photosensitive drum, regarding the laser beam reflected and deflected by the polygon mirror 611 in the exposure apparatus. A light receiving element such as a photodiode is provided as a synchronization detection sensor on the synchronization detection plate, and the synchronization detection sensor photoelectrically converts an incident laser beam and outputs a synchronization detection signal (DETP). The belt displacement signal (Δa) is a signal indicating displacement in the main transfer direction in the intermediate transfer belt, and the displacement in the main scanning direction of the intermediate transfer belt in the image transfer surface that occurs during belt deviation correction by the belt deviation adjusting means is belt skew. It is a signal calculated from information. The writing position control unit 607 combines the real image signal from the image signal generation unit 603 with the synchronization detection signal (DETP) at a predetermined timing, and generates a signal for driving the semiconductor laser as the light source. At this time, the “start timing” for writing the actual image signal from the synchronization detection signal is controlled in accordance with the belt displacement signal (Δa). Further, a skew correction clock signal (dclk) obtained by multiplying the pixel clock signal (wclk) generated by the pixel clock generation unit 605 by the multiplication circuit unit 606 is input to the writing position control unit 607. The skew correction clock signal (dclk) is obtained by multiplying the pixel clock signal (wclk) that defines the minimum pixel that can form an image, and is a signal having a higher frequency than the pixel clock signal, and is a transfer slit position sensor. This is a clock signal having a frequency corresponding to the detection resolution. One clock of the skew correction clock signal (dclk) corresponds to one resolution of the belt skew information. Assuming that A (= N × wclk) from the synchronization detection signal when the belt displacement signal (Δa) input to the writing position control unit 607 is 0 to the start position in the main scanning direction of the actual image signal, Δa> 0 is satisfied. If detected, the delay time from the synchronization detection signal to the actual image writing timing is changed to A + Δa × dclk, and the actual image writing start position is delayed with respect to the case where there is no belt skew. On the other hand, when Δa <0, the delay time is set to A−Δa × dclk, and the actual image writing start timing is relatively advanced. The laser drive signal synthesized by the writing position control unit 607 is input to the laser drive unit 612. The semiconductor laser mounted on the laser drive unit 612 is repeatedly driven to turn on / off by turning on / off the laser drive signal. The laser beam emitted by driving the semiconductor laser is incident on the laser writing means 608, passes through and reflects a plurality of lenses, mirrors, etc., and travels in the optical path. It is rotationally deflected by a polygon mirror 611 disposed in the middle of the optical path, and a laser beam is exposed on the photosensitive drum in the main scanning direction. The process from this exposure until an output image is obtained is as described above.

  In the above configuration, by controlling the latent image forming position on the image carrier based on the belt skew information, it is possible to prevent image distortion and color misregistration due to misregistration in the main scanning direction, and a high-performance control system that is expensive. It is possible to significantly improve the output image quality without providing high-precision optical means.

101, 102, 103, 104 Photosensitive drums 111, 112, 113, 114 Chargers 121, 122, 123, 124 Exposure devices 131, 132, 133, 134 Developers 200 Intermediate transfer belt 201 Detection line 205 Belt deviation detection means 211 Driving roller 212, 213 Driven roller 214 Tension roller 215 Steering roller 216 Actuator 217 Spring 218 Slider mechanism 219 Pressure sensor 220 Displacement sensor 601 Printer driver unit 602 Image writing control unit 603 Image signal generation unit 604 Engine control unit 605 Pixel clock generation unit 606 Multiplication circuit section 607 Writing position control section 608 Exposure apparatus (laser writing means)
609 Synchronization detection unit 609
611 Polygon mirror 612 Laser drive unit

Japanese Patent No. 3976924 JP 2006-276427 A JP 2008-129518 A

Claims (7)

Belt transport comprising an endless belt stretched and transported by a plurality of rollers, belt driving means for driving and rotating the endless belt, and belt deviation correcting means for correcting displacement in a direction orthogonal to the transport direction of the endless belt. In the device
A tension detection mechanism is provided at a predetermined position in the axial direction of at least one of the plurality of rollers,
A belt conveying apparatus comprising: an inclination calculating means for calculating an inclination of the endless belt in the belt traveling direction based on a measurement value detected by the tension detection mechanism.   As the tension detection mechanism, pressure sensors arranged at both ends of the roller to which the tension detection mechanism is to be attached are used, and the inclination of the endless belt is calculated based on the difference between the tension tension values detected by both pressure sensors. The belt conveyance device according to claim 1.   As the tension detection mechanism, displacement sensors arranged at both ends of a roller to which the tension detection mechanism is to be attached are used, and the inclination of the endless belt is calculated based on a difference between measured values detected by both displacement sensors. The belt conveyance device according to claim 1, wherein   As the tension detection mechanism, an inclination sensor disposed at one end of a roller to which the tension detection mechanism is to be attached is used, and the inclination of the roller detected by the inclination sensor is defined as the inclination of the endless belt. The belt conveyance device according to claim 1. At least one of a plurality of rollers that stretch and convey the endless belt is configured to be tiltable,
The belt conveying device according to any one of claims 1 to 4, wherein the inclination of the endless belt is corrected by tilting the roller based on the inclination data of the belt by the inclination calculating means. .   An image forming apparatus comprising the belt conveyance device according to claim 1. A latent image forming unit that forms a latent image on the image carrier based on the image data, a developing unit that visualizes the latent image formed on the latent image forming unit, and a possible image formed on the image carrier. An intermediate transfer member that primarily transfers a visual image and a secondary transfer unit that transfers a transfer image on the intermediate transfer member to a recording sheet, and sequentially transfers visible images formed on a plurality of image carriers. In an image forming apparatus that forms a color image by transferring onto a body,
The intermediate transfer member is the belt conveyance device according to any one of claims 1 to 4,
An image forming apparatus characterized in that a latent image forming position on an image carrier in an image forming unit is corrected based on belt inclination data by the inclination calculating means.

Images