JP2012189633A - Belt conveyance device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a belt conveyance device enabling easy detection and correction with a simple configuration, and to provide an image forming device including the same.SOLUTION: The belt conveyance device includes: a belt driving means; a belt position detection means 31 for detecting light having passed edge positions p1, p2 different in belt traveling direction S using one sensor 34; a belt deviation calculating means A1 for calculating deviation δ of an intermediate transfer belt 51 on the basis of light quantity signals Sp1, Sp2 obtained by the belt position detection means; a belt inclination calculation meats A2 for calculating the inclination θ of an endless belt in the belt traveling direction S; a belt deviation correcting means A3 for correcting the deviation δ of the endless belt; and a belt inclination correcting means A4 for correcting the inclination θ of the endless belt.

Description

  The present invention relates to a belt conveyance device used in an image forming apparatus such as a printer or a copying machine, and in particular, a belt conveyance device that stretches an endless belt with a plurality of rollers and circulates and drives the belt using any one of the rollers as a drive roller. And an image forming apparatus.

In image forming apparatuses such as copying machines, printers, plotters, facsimiles, and printing apparatuses, a toner image is formed on a photosensitive member used as a latent image carrier, and the toner image is formed on paper, an OHP sheet, tracing paper, or the like. The toner image is electrostatically transferred to a recording medium, and the transferred toner image is fixed to obtain a copy output.
The image obtained as a copy output includes not only a single color but also a plurality of color images including a full color. As one of the configurations for forming a multi-color image, a monochrome-like speed can be obtained even when obtaining a full color. A tandem type image forming apparatus having advantages is known.

As this image forming apparatus, there is a color image forming apparatus that forms a color image using an endless intermediate transfer belt, a photosensitive belt, and a paper conveying belt. As this type of color image forming apparatus, there is a tandem type image forming apparatus in which an image forming unit corresponding to each color of yellow, magenta, cyan, and black is individually provided on an endless belt such as an intermediate transfer belt.
In the endless belt conveying device used in this tandem image forming apparatus, the belt is different from the conveying direction due to the shape of the roller that stretches the belt, the inclination generated by the assembly, and the circumferential width difference of the belt originally possessed by the belt. A so-called belt shift occurs in which the belt moves in the orthogonal direction (width direction).

When the belt shift occurs, if the shift amount exceeds a predetermined amount, the belt end portion may come into contact with the components of the belt conveyance device and may be damaged. Further, in the image forming apparatus, it becomes a cause of image positional deviation.
In particular, in the case of the tandem type color image forming apparatus using an intermediate transfer belt, image forming means for forming images of different colors in order along the belt conveyance direction are arranged, and each color is transferred onto the intermediate transfer belt in an overlapping manner. At this time, color misregistration due to different positions in the width direction of the belt occurs.

Therefore, techniques for preventing belt misalignment have been conventionally proposed for image forming apparatuses.
As a typical belt deviation correction method, a steering method is known in which one of the rollers that stretch the belt is inclined to control the belt deviation. A method of controlling the belt shift by tilting the steering roller so that the belt moves in the opposite direction when the belt shift occurs, so that the shift amount originally generated and the shift amount by the steering are balanced. It is.

For example, Patent Document 1 includes a proportional-integral control unit that detects a shift in the position of the belt edge in accordance with a change in the amount of light from a belt position detection sensor, and the proportional-integral control unit detects the edge position of the transfer belt during image formation. Meandering correction means is controlled so as to be suppressed within the detection accuracy guarantee range (-P to + P) of the displacement sensor, thereby ensuring the running position accuracy of the transfer belt. When the transfer belt travel position is within the integral correction limit range (-I to + I), the position of the eccentric cam forming the meandering correction means is calculated from the sum of the proportional correction amount and the integral correction amount. The correction operation is promptly performed for the change, and the vibration of the transfer belt running position is suppressed.
In the steering system described above, in order to keep the belt position constant in the belt width direction, for example, a sensor is provided at one position in the belt conveyance direction to detect the edge position of the belt so that the edge position falls within a predetermined range. The tilt of the steering roller is controlled.

By the way, even if the edge position of the belt can be controlled by the steering, the posture of the belt at that time may be inclined due to the parallelism of the roller that stretches the belt or the circumferential length difference in the belt width direction.
Considering the posture of the belt center line, if the axes of all the rollers are parallel to each other and the rollers are perfectly cylindrical, the belt center line should be parallel to the plane perpendicular to the roller axis. If the belt is unfolded, the belt centerline is a straight line. However, if the axis of one of the rollers is not parallel to the other and is inclined even slightly, the center line of the belt does not become a straight line but is bent. Originally, the axes of all the rollers are parallel to each other, and the rollers are not completely cylindrical. Therefore, the belt center line is bent, which causes a belt shift. This can be balanced by the steering, but the belt center line is balanced in a bent state.

  In a color image forming apparatus, even if the belt is stopped, if the belt is tilted, it may cause color misregistration in which the positions of different colors are shifted in the belt width direction (main scanning direction). . Therefore, in the color image forming apparatus, the amount of color misregistration on the belt is detected, and the image forming position of each color in the belt width direction (main scanning direction) is adjusted to reduce the color misregistration. In many cases, matching is performed. However, if the steering operation is subsequently performed and the inclination angle of the steering roller changes, the inclination of the belt also changes, and the color misregistration state becomes worse.

  As a countermeasure against the above, by providing a plurality of sensors that detect the belt position in the belt width direction, the amount of belt inclination is detected, and belt inclination correction means provided separately from belt deviation correction means corrects belt inclination. A method to try is proposed.

  For example, in Patent Document 2, two first and second edge sensors are arranged in the vicinity of a pair of rolls around which an endless intermediate transfer belt 1 is suspended, whereby the edge position of the intermediate transfer belt is determined. Then, the belt inclination amount is detected from these detection results, and the belt inclination amount (belt skew amount) is corrected by belt inclination correction means provided separately from the belt meandering (deviation) correction means.

  In the method disclosed in Patent Document 2, the deviation and inclination of the belt are obtained and corrected, but a plurality of sensors dedicated to belt position detection in the belt width direction are required. For this reason, there exists a problem that it leads to the enlargement of an apparatus and a cost increase, and the request of avoiding the belt position detection by multiple sensors arises from this point.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a belt conveying apparatus and an image forming apparatus using the same that can detect and correct a belt shift and inclination with a simpler configuration.

  The present invention has the following configuration in order to achieve the above object.

  A belt conveyance device according to a first aspect of the present invention includes a belt driving unit that travels an endless belt, a belt position detection unit that detects light that has passed through different edge positions in the belt traveling direction, and the belt position detection unit. A belt deviation calculating means for calculating the deviation of the endless belt in the belt running direction based on the detection signal obtained by the belt, and a belt for calculating the inclination of the endless belt in the belt running direction based on the detection signal obtained by the belt position detecting means. Inclination calculating means; belt deviation correcting means for correcting deviation of the endless belt in the belt running direction based on the calculation result of the belt deviation calculating means; and the belt running direction based on the calculation result of the belt inclination calculating means. Belt inclination correcting means for correcting the inclination of the endless belt. To.

  A belt conveying apparatus according to a second aspect of the present invention is the belt conveying apparatus according to claim 1, wherein the belt position detecting means includes two light sources of different colors and a color image sensor.

  A belt conveyance device according to a third aspect of the present invention is the belt conveyance device according to claim 1, wherein the belt position detecting means includes a polarization sensor and a polarizing plate sandwiched between the light source and the polarization sensor. And

  According to a fourth aspect of the present invention, there is provided a belt conveying apparatus according to the first aspect, wherein the belt deviation correcting means and the belt inclination correcting means are provided at both ends of one roller, respectively.

  An image forming apparatus according to a fifth aspect of the invention includes the belt conveyance device according to any one of claims 1 to 4.

  According to the present invention, the belt deviation (position) in the belt width direction at a plurality of positions in the belt longitudinal direction is obtained by one sensor, the belt inclination is obtained from the difference between the detection signals, and provided separately from the belt deviation correction means. Since the belt inclination correcting means corrects the belt inclination based on the calculation result of the belt inclination calculating means, it is possible to prevent color misregistration due to a change in the inclination angle of the steering roller and a change in the inclination of the belt. ).

  Further, according to the present invention, the belt position detecting means comprising two light sources of different colors at a plurality of positions in the belt longitudinal direction and a single color image sensor is used to determine the belt position (position) of the plurality of positions, The belt inclination is obtained based on them, and the effect of claim 1 can be obtained reliably (claim 2).

  Further, according to the present invention, two light sources at a plurality of positions in the belt longitudinal direction and light from these light sources are polarized through the first and second polarizing plates, and detected by a single polarization sensor. Thus, a plurality of belt deviations (positions) can be obtained, and the belt inclination can be obtained based on them, so that the effect of claim 1 can be reliably obtained. (Claim 3).

  Further, according to the present invention, since the belt deviation correction means and the belt inclination correction means are provided at both ends of one roller, the belt deviation (position) and the belt inclination are obtained at both ends, respectively, and the belt inclination is determined based on them. The effect of claim 1 can be obtained more reliably. (Claim 4).

  Further, according to the present invention, the image forming apparatus can achieve the effects of the inventions of the first to fourth aspects (claim 5).

1 is a side view showing the overall configuration of a belt conveying apparatus according to the present invention and a copier as an image forming apparatus including the apparatus. FIG. FIG. 2 is an overall plan view of an image forming unit of the copier of FIG. 1. FIG. 2 is a schematic side view of a main part of an image forming unit of the copier of FIG. 1. FIG. 2 is a perspective view of a steering roller and a belt position correcting unit of the image forming unit of the copying machine of FIG. 1. FIG. 2 is a partial side view of a steering roller and a belt position correcting unit of the image forming unit of the copying machine of FIG. 1. FIGS. 2A and 2B are explanatory views of displacement of a steering roller and an intermediate transfer belt in the image forming unit of the copying machine of FIG. 1, and FIG. 2A and 2B are explanatory views of tilt displacements of a steering roller and an intermediate transfer belt of the image forming unit of the copying machine of FIG. 1, wherein FIG. FIG. 2 is a functional explanatory diagram of belt position detecting means of the image forming unit of the copying machine of FIG. 1. 3 is a flowchart of a belt position restriction control routine of the belt conveyance device of the copying machine of FIG. 1. 6 is a flowchart of a belt position restriction control routine of a belt conveyance device of a copying machine as a second embodiment.

A belt conveyance device and an image forming apparatus to which the present invention is applied will be described.
Here, as the “first embodiment”, a color toner image formed by a plurality of image forming process means (image forming units) is primarily transferred to an intermediate transfer belt, and the color toner image transferred in the same overlapping manner is used as a recording medium. When obtaining a color image by secondary transfer, an intermediate transfer type belt conveyance device is provided in which the belt conveyance device is provided with means for correcting the shift and inclination of the intermediate transfer belt in the belt running direction so as to suppress the occurrence of color misregistration. A copier M that is an image forming apparatus including the same apparatus will be described.
FIG. 1 shows a schematic configuration diagram of a copying machine M as a “first embodiment”. The copying machine M includes a printer unit (image forming unit) 1 that forms an image on a recording sheet as a recording medium, a paper feeding device 200 that supplies the recording sheet P to the printer unit 1, and a scanner 300 that reads an original image. The scanner 300 includes an automatic document feeder (hereinafter referred to as ADF) 400 for automatically feeding a document.

  The scanner 300 is placed on the contact glass 301 as the first traveling body 303 equipped with a document illumination light source or mirror and the second traveling body 304 equipped with a plurality of reflecting mirrors reciprocate. Scanning of a document (not shown) is performed. The scanning light sent out from the second traveling body 304 is condensed on the imaging surface of the reading sensor 306 installed behind the imaging lens 305 and then read as an image signal by the reading sensor 306. The image signal received from the scanner 300 is subjected to predetermined image processing by a control unit (not shown), and its output is transmitted to the printer unit 1 to form an image.

On the side surface of the apparatus main body 99 of the printer unit 1, the manual feed tray 102 for manually placing the recording paper P to be fed into the apparatus main body 99 and the image-formed recording paper P discharged from the apparatus main body 99 are provided. A stacking tray 103 is provided.
In the apparatus main body 99 of the printer unit 1, an intermediate transfer unit 50 is disposed as a transfer unit that stretches an endless intermediate transfer belt 51 as an image carrying belt in a loop shape. The intermediate transfer unit 50 includes a loop-shaped intermediate transfer belt 51 which is a first intermediate transfer member constituting the main part thereof.

The intermediate transfer belt 51 includes a driving roller (belt driving unit) 7 that is driven to rotate counterclockwise in the drawing by a driving unit (not shown), a steering roller 8 that is a driven roller, and a primary transfer unit between both rollers 7 and 8. Are stretched by primary transfer rollers 55Y to 55K, a secondary transfer counter roller 54 inside the lower part of the intermediate transfer belt 51, and a tension roller 9 downstream of the secondary transfer counter roller.
The subscripts Y, C, M, and K attached to the end of the reference numeral of the primary transfer roller 55 indicate yellow, cyan, magenta, and black members. Hereinafter, the subscripts Y, C, M, and K attached to the ends of the symbols are the same.

The intermediate transfer belt 51 is largely curved through auxiliary rows 13 and 14 at the left and right ends of the driving roller 7 and the steering roller 8 which is a driven roller, so that the bottom is directed upward in the vertical direction. It is stretched in a triangular shape.
The belt upper stretch surface f corresponding to the base of the inverted triangle extends in the horizontal direction, and above the belt upper stretch surface f, four color process units (image forming units) 10Y, C, M and K are arranged so as to be aligned in the horizontal direction along the extending direction of the upper stretched surface f.

  Above these four process units 10Y, 10C, 10M, and 10K, an optical writing unit 68 is disposed. The optical writing unit 68 receives plate data of each color from writing control means (not shown) based on the image information of the original read by the scanner 300, and four semiconductor lasers (not shown) by a laser control unit (not shown). ) To emit four writing lights L. Then, the drum-shaped photoconductors 11Y, 11C, 11M, and 11K serving as latent image carriers of the process units 10Y, 10C, 10M, and 10K are scanned in the dark by the writing light L, respectively. , K, electrostatic latent images for Y, C, M, and K are written.

In the first embodiment, as the optical writing unit 68, the laser beam emitted from the semiconductor laser is deflected by a polygon mirror (not shown), reflected by a reflection mirror (not shown), or passed through an optical lens to perform optical scanning. Use what you do.
Next, the process units 10Y, 10C, 10M, and 10K will be described with respect to the Y process unit 10Y as a representative.
The process unit 10Y includes a charging member 12Y, a drum cleaning device 14Y, a developing device 20Y, and the like around a drum-shaped photoconductor 11Y that is in contact with the intermediate transfer belt 51, and a casing (not shown) serving as a common holding body. ) Is integrally attached to and detached from the printer unit 1 as a unit.

Here, the charging member 12Y uniformly charges the surface of the photoreceptor 11Y to the same polarity as the charging polarity of the Y toner, for example. In the developing device 20Y, the Y toner in the Y developer is transferred to the electrostatic latent image by the action of the developing potential, whereby the electrostatic latent image on the photoreceptor 11Y is developed into the Y toner image. The cleaning device 14Y contacts the brush tip of the brush roller 141Y having innumerable conductive brushes with the photoconductor 11Y, scrapes the residual toner from the photoconductor 11Y, discharges it out of the casing, and recycles toner (not shown). Return to the means side. The surface of the photoreceptor 11Y from which the transfer residual toner has been cleaned by the drum cleaning device 14Y is neutralized by a neutralization device (not shown) and then uniformly charged by the charging member 12Y.
Here, the Y process unit 10Y has been described in detail, but the process units (10C, M, K) of other colors have the same configuration as that of Y except that the color of the toner used is different. ing.

  The photosensitive drums 11Y, 11C, 11M, and 11K of the process units 10Y, 10C, 10M, and 10K rotate while abutting against the upper stretched surface of the intermediate transfer belt 51 that is endlessly moved counterclockwise. , C, M, and K primary transfer nips are formed. These primary transfer nips for Y, C, M, and K are provided on the back side of the intermediate transfer belt 51 via the intermediate transfer belt 51, and the primary transfer rollers 55 Y, C, M, and K described above are provided on the back side of the intermediate transfer belt 51. Deployed to abut. A primary transfer bias having a polarity opposite to the charging polarity of the toner is applied to each of the primary transfer rollers 55Y, 55C, 55M, 55K by a bias supply unit (not shown). Due to this primary transfer bias, a primary transfer electric field is formed in the primary transfer nips for Y, C, M, and K to electrostatically move the toner from the photoreceptor side to the belt side. The Y, C, M, and K toner images formed on the photosensitive drums 11Y, 11C, 11M, and 11K are used for Y, C, M, and K as the photosensitive drums 11Y, 11C, 11M, and 11K rotate. When entering the primary transfer nip, primary transfer is performed by sequentially overlapping the writing position on the intermediate transfer belt 51 by the action of the primary transfer electric field and nip pressure. As a result, a four-color superimposed toner image (hereinafter referred to as a four-color toner image) is formed on the front surface (loop outer peripheral surface) of the intermediate transfer belt 51. Instead of the primary transfer rollers 55Y, 55C, 55M, 55K, a conductive brush to which a primary transfer bias is applied, a non-contact type corona charger, or the like may be employed.

  As shown in FIG. 1, an optical sensor unit 69 is disposed on the right side of the drive roller 7 in the drawing so as to face the front surface of the intermediate transfer belt 51 with a predetermined gap. . The optical sensor unit 69 detects a mark (not shown) provided at a predetermined pitch in the belt circumferential direction at one end of the intermediate transfer belt 51 in the belt width direction. The moving speed of the intermediate transfer belt 51 can be measured based on the detection time interval of each mark.

A secondary transfer counter roller 52 is disposed inside the lower portion of the intermediate transfer belt 51, and this is rotationally driven counterclockwise in the drawing by a driving means (not shown) to form a secondary transfer portion. The secondary transfer counter roller 52 forms an electric field between the secondary transfer counter roller 52 and the secondary transfer backup roller 53 disposed outside the intermediate transfer belt 51 in contact therewith. The four-color toner image formed on the front surface of the intermediate transfer belt 51 is transferred to the recording paper P by being transferred at the secondary transfer nip E which is a transfer area as the intermediate transfer belt 51 moves endlessly. Is done.
Both ends of the secondary transfer backup roller 53 are pivotally supported by a support frame 531, and the support frame 531 is pressed by a compression spring 533 around a fulcrum shaft 532, whereby secondary transfer backup to the intermediate transfer belt 51 side. The pressing force of the roller 53 is held at an appropriate value.

The tension roller 9 contacts the secondary transfer counter roller 52 from the outside of the belt on the downstream side of the belt. In FIG. 1, the tension roller 9 is elastically pressed against the belt by the spring member 901 at the front side and the back side shaft ends, thereby functioning to apply a predetermined tensioning force to the belt.
In FIG. 1, a paper feeding device 200 includes a paper feeding cassette 201 that stores recording paper P, a paper feeding roller 202 that feeds the recording paper P stored in these paper feeding cassettes 201 to the outside of the cassette, and a fed recording paper P A plurality of separation roller pairs 203 for separating the sheets one by one, a plurality of conveyance roller pairs 205 for conveying the separated recording paper P along the delivery path 204, and the like are provided. The sheet feeding device 200 is disposed directly below the printer unit 1 as shown in the figure. The feeding path 204 of the paper feeding device 200 is connected to the paper feeding path 70 of the printer unit 1.

Near the end of the paper feed path 70 of the printer unit 1, a registration roller pair 71 is provided as a feeding means, and the recording paper P sandwiched between the rollers is a four-color toner image on the intermediate transfer belt 51. To the secondary transfer nip E at a timing synchronized with At the secondary transfer nip E, the four-color toner images on the intermediate transfer belt 51 are secondarily transferred onto the recording paper P under the influence of the secondary transfer electric field and the nip pressure, and combined with the white color of the recording paper P, Become.
As shown in FIG. 1, a fixing device 80 is provided on the right side of the secondary transfer nip E as a transfer area in the drawing. The recording paper P sent to the fixing device 80 is sandwiched in a fixing nip formed by a heating roller 81 containing a heat source (not shown) and a pressure roller 82 pressed toward the heating roller 81. After being sandwiched and heated while being pressed, the full-color image is fixed on the surface, and then sent to the outside of the fixing device 80.
As shown in FIG. 2, a slight amount of secondary transfer residual toner that has not been transferred to the recording paper P adheres to the surface of the intermediate transfer belt 51 after passing through the secondary transfer nip E that is a transfer area. is doing. The secondary transfer residual toner is removed from the belt by a belt cleaning device 57 that is in contact with the surface of the intermediate transfer belt 51 that is opposed to the driven roller 54.

  As shown in FIG. 1, a switchback device 85 is disposed below the fixing device 80. When the recording paper P discharged from the fixing device 80 reaches the conveyance path switching position by the swingable switching claw 86, the paper discharge roller pair 87 is set according to the swing stop position (each switching position) of the switching claw 86. Or to the switchback device 85. When the paper is sent toward the paper discharge roller pair 87, the paper is discharged to the outside of the apparatus and then stacked on the paper discharge tray 3. On the other hand, when it is sent to the switchback device 85, it is turned upside down by the switchback conveyance by the switchback device 85, and is then conveyed again toward the registration roller pair 71, and again to the secondary transfer nip. A full color image is formed on the other side as it enters.

  The intermediate transfer belt 51 shown in FIGS. 2 and 3 is stretched in a substantially inverted triangular posture by the drive roller 7, the steering roller 8, and the secondary transfer roller 54, and the belt tension is adjusted to an appropriate value by the tension roller 9. keeping. The intermediate transfer belt 51 has a belt upper stretched surface f corresponding to the bottom of the intermediate transfer belt 51 extending in the horizontal direction. Above the belt upper stretched surface f, four color process units (image forming units) 10Y, C,. Since M and K are arranged so as to be aligned horizontally along the extending direction of the upper stretched surface f, if a belt shift or tilt occurs during image formation, color misregistration will occur. A belt position restricting mechanism is provided.

As shown in FIGS. 2 and 3, the belt position regulating mechanism includes a belt position detection unit 31, a belt position correction unit 32 that adjusts the inclination of the steering roller 8, and a belt position control unit 33 that controls the belt position correction unit 32. Is provided. The belt position control means 33 has functions of a belt deviation calculating means A1, a belt inclination calculating means A2, a belt deviation correcting means A3, and a belt inclination correcting means A4.
As shown in FIGS. 2 and 3, the belt position detection means 31 is configured to condense light at two locations that have passed through edge positions p <b> 1 and p <b> 2 in the belt traveling direction S and detect them with a single sensor 34. The

If the explanation is added, the belt position detecting means 31 is arranged at two positions p1 and p2 that are different from each other in the belt traveling direction S on the belt traveling path provided on the upper stretched surface f from the steering roller 8 to the driving roller 7. Light sources 351 and 352 are provided. Of these, one light source 351 is disposed between the auxiliary roller 13 and the primary transfer roller 55Y (upstream side), and the other light source 352 is disposed between the primary transfer roller 55K and the auxiliary roller 14 (downstream side). The detection light is irradiated toward the belt 51 (see FIG. 3).
Here, the first and second light sources 351 and 352 irradiate the edge positions p1 and p2 of the intermediate transfer belt 51 at the respective arrangement positions, and respectively irradiate from the front side to the back side of the belt 51 (see FIG. 8). . The light that has passed through the edge position p1 is directly applied to the light receiving element 34, and the light emitted from the edge position p2 is reflected by the mirror 353 and applied to the light receiving element 34. Here, the light passes through the edge positions p1 and p2 with different belt running directions. The received light is detected by one light receiving element 34.

  The first and second light sources 351 and 352 are different from each other, and here, LEDs (Light Emitting Diodes) are used as the two light sources of different colors.

On the other hand, the color image sensor 34, which is a single light receiving element, only needs to have a function capable of identifying and detecting different lights, and here, a color CCD image sensor (Charge Coupled Device Image Sensor) is used.
A light amount signal (analog signal) corresponding to the position, which is the light amount information output from the color CCD image sensor 34 at these two positions, is b in the belt width direction b at the edge position p1 (p2) of the belt 51 as shown in FIG. It increases / decreases according to the deviation in the belt and includes belt deviation information. This light quantity signal is A / D converted at a predetermined detection period by an analog signal processing circuit and a sample and hold circuit (not shown), and the light quantity signals Sp1 and Sp2 are detection signals corresponding to the two positions p1 and p2 for each color. (Digital signal) is input to the controller 33.

As shown in FIGS. 4 and 5, the belt position correcting means 32 for adjusting the inclination of the steering roller 8 includes first and second steering adjusting means 321 and 322 for correcting the deviation and inclination of the belt.
4 and 5, the shaft end 801 of the steering roller 8 on the near side in FIG. 4 and FIG. 5 is moved by the first steering adjusting means 321, and the end of the belt is moved from the broken line position to the solid line position in FIG. Correct the shift. 4 and 5, the shaft end portion 801 of the steering roller 8 on the back side is moved by the second steering adjustment means 322, the end portion of the belt is moved from the broken line position in FIG. Correct the tilt.

  As both the first and second steering adjustment units 321 and 322 shown in FIGS. 2 to 4, a generally used mechanism may be employed. Here, as shown in FIGS. 2 and 4, the first steering adjustment means 321 moves the bearing member 802 that supports the shaft end 801 of the steering roller 8 or the support member 803 that supports the bearing member 802 in a certain direction ( It can be moved only in the vertical direction. In addition, a mechanism is used in which the cam 805 is brought into contact with and moved through a lateral lever 804 that is operated by the bearing member 802 or the bearing support member 803. Reference numeral 810 denotes a return spring that presses the lateral lever 804 toward the cam, and reference numeral 812 denotes a pivot member of the lateral lever 804.

  On the other hand, as shown in FIGS. 2 and 4, the second steering adjustment means 322 moves the bearing member 802 that supports the shaft end 801 of the steering roller 8 or the support member 803 that supports the bearing member 802 in a certain direction ( It can be moved only in the vertical direction. In addition, a mechanism is used in which the cam 807 is brought into contact with and moved through a longitudinal lever 806 that is operated by the bearing member 802 or the bearing support member 803. Reference numeral 811 denotes a return spring that presses the vertical lever 806 toward the cam, and reference numeral 813 denotes a pivot member of the vertical lever 806.

Here, the cam 805 is rotated by the first motor 808, and the first motor 808 is driven by the controller 33, and the shaft end 801 of the steering roller 8 is swung up and down (reference a direction) to move the belt end. Increase or decrease displacement in the direction (see symbol a1 in FIG. 6A).
On the other hand, the cam 807 is rotated by a second motor 809, and the second motor 809 is driven by the controller 33 to swing the shaft end 801 of the steering roller 8 in the horizontal direction (reference sign b direction). Is increased or decreased in the tilt direction (see symbol b1 in FIG. 6B).
Instead of this, a linear actuator that translates may be used.

Further, in FIG. 2 described above, the control signal regarding the belt shift outputted from the controller 33 is given to the first steering adjusting means 321 shown in FIG. 4 and the control signal concerning the belt inclination is given to the second steering adjusting means 322. .
The belt position control means 33 for controlling the belt position correction means 32 has functions of a belt deviation calculation means A1, a belt inclination calculation means A2, a belt deviation correction means A3, and a belt inclination correction means A4.
Here, the belt deviation calculation means A1 of the belt position control means 33 is based on the light quantity signals Sp1 and Sp2 which are detection signals of the quantity of light passing through the positions p1 and p2 sent from the color CCD image sensor 34. A shift amount δ (see FIG. 2) is calculated. Specifically, when red (R) is used for the first light source 351 and green (G) is used for the second light source 352, the average value of the light amount signals Sp1 (detection signal: R) and Sp2 (detection signal: G) is the belt. It corresponds to the amount of shift.

The belt inclination calculating means A2 calculates the belt inclination amount θ of the intermediate transfer belt 6 based on the difference between the light quantity signals Sp1 and Sp2 which are detection signals corresponding to the two positions p1 and p2 sent from the color CCD image sensor 34.
Specifically, when red (R) is used for the first light source 351 and green (G) is used for the second light source 352, the difference between the light amount signals Sp1 (detection signal: R) and Sp2 (detection signal: G) is the belt inclination. It corresponds to the quantity θ.
The belt deviation correction unit A3 erases the deviation of the endless belts based on the deviation amount δ of the intermediate transfer belt 6 which is the calculation result of the belt deviation calculation unit A1. Control to switch to.

The belt inclination correction means A4 erases the inclination of the endless belt by using both the first and second steering adjustment means 321 and 322 based on the belt inclination amount θ of the intermediate transfer belt 6 which is the calculation result of the belt inclination calculation means A2. Switching control is performed as follows.
Next, a case where a document is copied by the copying machine M according to the first embodiment will be described.
First, when a document is set on the automatic document feeder 400 or a document is set on the automatic document feeder 400 and a start switch (not shown) is pressed, a preset copy mode operation starts. Then, reading scanning of the scanner 300, driving of the intermediate transfer unit 50 and each color process unit 10Y, C, M, and K, and feeding of the recording paper P from the paper feeding device 200 are started.

Next, in accordance with a general electrostatic recording system, the electrostatic latent images of the respective colors are written on the photosensitive drums 11Y to 11K by the light writing means 68, and the electrostatic latent images are developed into the developing devices 20Y, M, C, The toner image is visualized by K, and the toner images are sequentially transferred to the same image forming area of the intermediate transfer belt 51 to obtain a superimposed toner image. The color toner image superimposed and transferred on the intermediate transfer belt 51 has been conveyed to the secondary transfer nip E between the secondary transfer counter roller 52 and the secondary transfer backup roller 53 disposed via the intermediate transfer belt 51. Secondary transfer is performed with a transfer bias applied to the recording paper.
The transfer paper P after the secondary transfer is fixed by the fixing device 80 and discharged to the paper discharge tray 3, whereby a full color final image can be obtained on the recording paper P.

Next, belt position restriction control performed by the controller 33 of the belt conveyance device provided in the copying machine M of FIG. 1 will be described along the belt position restriction control routine of FIG.
The image forming apparatus is powered on, and the intermediate transfer belt 6 starts to run by the rotation of the driving roller 7 (step s1). Thereafter, the controller 33 obtains light amount signals Sp1 and Sp2 which are detection signals of light (red (R) and green (G)) transmitted from the two positions p1 and p2 sent from the color CCD image sensor 34 in step s2. Edges p1 and p2 are detected.
In step s3, based on the light quantity signals Sp1 and Sp2, the average value (δ1 + δ2) / 2 of the respective deviation amounts δ1 and δ2 is set to the belt deviation amount δ (in FIG. 6A, a deviation amount is generated only at the position P1. Calculated).

Further, as shown in FIG. 7A, light quantity signals Sp1, Sp2 (shift amounts δ1, δ2) which are detection signals of light (red (R) and green (G)) that have passed through two positions p1, p2. The belt inclination amount θ of the intermediate transfer belt 6 is calculated based on the difference.
Next, in step s4, it is determined whether the belt deviation amount δ is smaller than a predetermined allowable value ± α that can be regarded as not requiring correction, and the process proceeds to step s6 with Yes, and to step s5 with No. When the deviation amount δ exceeds the allowable value ± α and reaches step s5, the first and second steering adjustment means 321 and 322 are operated with a control signal having a value corresponding to canceling this based on the detection signal of the belt deviation amount δ. By adjusting the inclination of the steering roller 8 in the direction of symbol a, for example, as indicated by a two-dotted line in FIG. 6B, the detected belt deviation amount δ is constant within the allowable value ± α. Control to be.

  Next, it is assumed that the shift amount δ is within the allowable value ± α and reaches s6 from step s4. Here, the controller 33 obtains the difference between the shift amounts δ1, δ2) which is the difference between the latest light amount signals Sp1, Sp2, and uses the distance La between the two positions p1, p2, and the belt inclination amount θ of the intermediate transfer belt 6. Calculate and import. After that, it is determined whether or not the belt inclination amount θ exceeds the allowable value ± θa, and the process proceeds to Yes in step s7. When the belt inclination amount θ exceeds the allowable value ± θa and reaches step s7, the first and second steering adjustment means 321 and 322 are controlled by a control signal having a value corresponding to canceling this based on the detection signal of the belt inclination amount θ. By operating, the detected belt inclination amount θ is controlled to be constant within the allowable value ± θa.

If both the belt deviation amount δ and the belt inclination amount θ are within the allowable values ± α and ± θa by the above processing, the process proceeds to No in step s6, the control of this time is finished, and the standby state of the image forming job is reached. It becomes.
In this way, the belt deviation amount δ in the belt width direction at the two positions in the belt traveling direction S is obtained by one color CCD image sensor 34, the belt inclination θ is obtained from the difference between the detection signals, and the belt deviation correction means A3. Since the belt inclination correction means A4 provided separately corrects the belt inclination θ based on the calculation result of the belt inclination calculation means A2, the inclination (inclination angle) θ of the steering roller 8 changes and the inclination of the belt changes. Color misregistration can be prevented.

Incidentally, the edge shape of the intermediate transfer belt 6 is not strictly a straight line due to the convenience of belt manufacture and the belt material.
Therefore, belt position restriction control performed by the controller 33 of the belt conveyance device as the second embodiment will be described. In addition, since the belt conveyance apparatus as 2nd Embodiment takes the same structure except belt position control control of FIG. 9 compared with 1st Embodiment, duplication description is abbreviate | omitted.
FIG. 10 shows the belt position restriction control process used in the second embodiment. In addition, the same code | symbol was attached | subjected to the duplication step and duplication description was abbreviate | omitted.

In the belt position restriction control of FIG. 10, in order to obtain the inclination more accurately by preventing the influence of the edge irregularities of the intermediate transfer belt 6, the average for one rotation of the belt is obtained.
That is, in this case, in addition to the steps in FIG. 9, step s8 is performed so that steps s2 and s3 are continued for one rotation of the belt at predetermined time intervals. The detected output is continuously taken in a predetermined time interval, the average value of each light source for one rotation of the belt is obtained, and when the process proceeds to steps s4 and s6 with the obtained average value of each light source, the amount of belt shift Both δ and the belt inclination amount θ are compared with the permissible values ± α and ± θa, and deviation correction and inclination correction are performed.

In the case of the second embodiment, both the belt shift and the belt tilt are properly controlled, and even if a disturbance occurs in the data, the influence of the disturbance can be reduced.
By the way, in general, the tilting operation by the first and second steering adjusting means 321 and 322 affects both the belt shift and the belt tilt. For this reason, after completing the above-described step s4, that is, by repeating the above-described processing, the belt shift amount is sufficiently reduced and the process proceeds to step s6 to correct the belt inclination, so that accurate control is possible. ing.

  In addition, it is conceivable that the belt characteristics fluctuate due to environmental changes (such as temperature changes) during an image forming job. In this case, in the main routine (not shown), the controller 33 operates the belt position detecting means 31 to monitor the belt deviation and the belt inclination, and determines whether the belt deviation and the belt inclination of a certain amount or more have occurred. It may be added. In this case, the controller 33 interrupts the image forming job at an appropriate timing when the belt shift and the belt inclination of a certain amount or more occur, and, for example, shifts to the belt position restriction control processing routine of FIGS. By correcting the belt deviation and the belt inclination, it is possible to always realize a stable belt running.

As described above, the present invention may be applied to any one of a facsimile machine, a printer, a printing machine, and an inkjet recording apparatus, or a combination of at least two of them, in addition to a copier, a multifunction machine including a scanner and a printer. The present invention may also be applied to an image forming apparatus including a multifunction machine.
Also in each of these embodiments, a belt position restriction mechanism is provided that prevents the belt deviation or inclination of the intermediate transfer belt 51 from occurring during image formation to prevent color misregistration, and belt position detection means of the belt position restriction mechanism. 31, belt position correcting means 32 for adjusting the inclination of the steering roller 8, and belt position control means 33 for controlling the belt position correcting means 32, thereby correcting belt misalignment and belt inclination, and always stable belt running. It is possible to achieve the effect that it is possible to realize.

1 Printer section (image forming section)
7 Drive roller (belt drive means)
8 Steering roller 31 Belt position detection means 32 Belt position correction means 33 Belt position control means 34 Color image sensor (light receiving element)
351, 352 First and second light sources 51 Intermediate transfer belt (endless belt)
δ shift θ inclination p1, p2 Edge position A1 Belt shift calculation means A2 Belt tilt calculation means A3 Belt shift correction means A4 Belt tilt correction means S Belt running direction Sp1, Sp2 Light quantity signal (detection signal)

JP 2007-003647 A Japanese Patent No. 3976924

Claims (5)

Belt driving means for running the endless belt;
Belt position detecting means for detecting light that has passed through different edge positions in the belt running direction with one sensor;
Belt deviation calculating means for calculating an endless belt deviation in the belt running direction based on a detection signal obtained by the belt position detecting means;
Belt inclination calculating means for calculating the inclination of the endless belt in the belt traveling direction based on the detection signal obtained by the belt position detecting means;
Belt deviation correction means for correcting deviation of the endless belt in the belt traveling direction based on the calculation result of the belt deviation calculation means;
Belt inclination correction means for correcting the inclination of the endless belt in the belt traveling direction based on the calculation result of the belt inclination calculation means;
A belt conveying device comprising: The belt position detecting means includes two light sources of different colors,
A color image sensor,
The belt conveyance device according to claim 1, further comprising: The belt position detecting means is a polarization sensor;
A polarizing plate sandwiched between a light source and a polarization sensor;
The belt conveyance device according to claim 1, further comprising: The belt deviation correcting means and the belt inclination correcting means are provided at both ends of one roller, respectively.
The belt conveying apparatus according to claim 1. The belt conveyance device according to any one of claims 1 to 4 is provided.
An image forming apparatus.

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