JP2007269421A - Sheet conveying device and image forming device provided with this - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet conveying device capable of accurately correcting position deviation of a sheet in a width direction of a sheet conveying passage and oblique advancement of the sheet relative to a sheet conveying direction, and an image forming device provided with this. <P>SOLUTION: The sheet conveying device has a width direction detection means comprising a line sensor 104 or 105 extending in the width direction of the sheet conveying passage and arranged at a position where at least one side edge of the sheet P is passed; an oblique advancement amount detection means in which a plurality of line sensors 104, 105 extending in the width direction of the conveying passage and arranged at a position where at least one side edge of the sheet is passed are arranged in the sheet conveying direction at a clearance narrower than sheet length; and a width direction correction means and an oblique advancement amount correction means 201-204 for feedback-loop-correcting the width direction position and the oblique advancement amount until the detection result of both detection means becomes a desired value. The sheet is conveyed while correcting the width direction position and the oblique advancement amount in the desired state and formation of an image is performed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sheet conveying apparatus and an image forming apparatus including the sheet conveying apparatus, and in particular, corrects a sheet positional deviation in the sheet conveying path width direction and a sheet skew in the sheet conveying direction during sheet conveying to correct the sheet positional deviation. The present invention also relates to a sheet conveying apparatus that reduces skew and an image forming apparatus including the sheet conveying apparatus.

  2. Description of the Related Art Conventionally, there is an image forming apparatus configured to obtain a monochrome image as shown in FIG. FIG. 8 shows an image forming apparatus for an electrophotographic process. In FIG. 8, reference numeral 1 denotes a rotating drum type photoconductor as an image carrier. The photoreceptor 1 is formed by forming a photoconductive layer of an inorganic photoreceptor such as amorphous silicon on the outer peripheral surface of a grounded aluminum cylinder. The photosensitive member 1 is rotationally driven in a clockwise direction at a predetermined peripheral speed (process speed) as indicated by an arrow in FIG.

  Reference numeral 2 denotes a contact charging roller as a charging device, which is rotated by being driven by the photoreceptor 1. A predetermined voltage is applied to the charging roller 2 from a primary charging bias power source (not shown), whereby a primary charging process is performed, and the peripheral surface of the photoreceptor 1 is uniformly charged to a predetermined potential with a predetermined polarity. The voltage applied from the primary charging bias power source is corrected according to the surface potential of the photoreceptor 1 detected by the surface potential detecting means 81.

  Next, the exposure device 3 performs exposure L along the scanning line according to the target image information on the primary charging processing surface of the photoreceptor 1, whereby the electrostatic latent image corresponding to the image information is formed on the peripheral surface of the photoreceptor 1. An image is formed.

  Next, a predetermined voltage is applied to the developing device 4 from a developing bias power source (not shown), whereby the latent image is developed as a toner image. On the other hand, a sheet P is fed at a predetermined timing from a sheet feeding unit (not shown) to a transfer nip portion where a transfer roller 53 as a transfer device is in pressure contact with the photoreceptor 1, and a toner image is transferred to the sheet P at the transfer nip portion. It will be transcribed. A transfer bias voltage having a polarity opposite to the charging polarity of the toner is applied to the transfer roller 53.

  The sheet P on which the toner image is transferred at the transfer nip portion is introduced into the fixing device 7 by a conveyance unit (not shown). Then, the sheet P on which the toner image is fixed as a permanent image by the fixing device 7 is output as an image formed product.

  After the toner image is transferred to the sheet P, the cleaning device 6 removes transfer residual toner and the like from the surface of the photoconductor 1 to clean the surface of the photoconductor 1. The removed toner is used for image formation.

  Further, an image forming method is known in which a color image is obtained on a sheet P by superimposing a plurality of color toner images. For example, as shown in FIG. 9, an electrostatic latent image is formed on the photosensitive member 1, and this electrostatic latent image is successively developed as each color toner image by four color developing means 4a to 4d. Then, each color toner image is transferred onto the intermediate transfer belt 51 by the primary transfer means 53, and the color toner images of a plurality of colors are superimposed on the intermediate transfer belt 51. Further, these color toner images are collectively transferred onto the sheet P by the secondary transfer means 56 and 57 and fixed by the fixing means 7. 55 is an intermediate transfer belt cleaner.

  In recent years, a so-called tandem type multiple transfer system has been widely employed in which a process unit such as a photoconductor and a developing device is separately provided for each color and a full color image can be formed in one pass.

  FIG. 10 shows an image forming apparatus of a tandem type multiple transfer system. In FIG. 10, 1a to 1d are photosensitive members, 2a to 2d are primary charging means, 3a to 3d are exposure means, 4a to 4d are developing means, and 53a to 53d are primary transfer means. Reference numerals 6a to 6d denote cleaners, 51 denotes an intermediate transfer belt, and 55 denotes an intermediate transfer belt cleaner. Reference numerals 56 and 57 denote secondary transfer means, and 81a to 81d denote surface potential detection means.

  In this image forming apparatus, after the photoconductors 1a to 1d are uniformly charged by the primary charging units 2a to 2d, exposures La to Ld corresponding to the image signals are made by the exposure units 3a to 3d. An electrostatic latent image is formed on 1a-1d. Thereafter, the toner images are developed by the developing means 4a to 4d, and the toner images on the four photoconductors 1a to 1d are multiplexed and transferred onto the intermediate transfer belt 51 by the primary transfer means 53a to 53d, and further the secondary transfer means 56. , 57 to the sheet P. The transfer residual toner remaining on the photoreceptors 1 a to 1 d is recovered by the cleaners 6 a to 6 d, and the transfer residual toner remaining on the intermediate transfer belt 51 is recovered by the intermediate transfer belt cleaner 55. The toner image transferred to the sheet P is fixed by the fixing means 7, thereby obtaining a color image.

  Each of the image forming apparatuses is required to accurately transfer the toner image to a desired position on the sheet P. Therefore, means as shown in FIG. 11 and FIG. 12 have been proposed for the purpose of appropriately correcting the skew and the width direction deviation of the sheet P (see, for example, Patent Documents 1 and 2).

  In the image forming apparatus shown in FIG. 11, the two line sensors 101 and 102 are spaced apart from each other in the sheet conveying path width direction and arranged in parallel to the sheet conveying direction. In addition, skew correction rollers 203 and 204 that can be driven independently from each other by driving rollers 201 and 202 are arranged apart from each other in the sheet conveyance path width direction at the same position as seen in the sheet conveyance direction. Then, the skew feeding amount is detected based on the difference between the leading edge positions a and b of the sheet P detected by the line sensors 101 and 102, and based on this skew feeding amount, the sheet feeding speed of the skew feeding correction rollers 203 and 204 or both of them is detected. The frictional force of the rollers 203 and 204 with respect to the sheet is controlled to correct the skew amount of the sheet.

In the image forming apparatus of FIG. 12, the line sensor 103 having a length longer than the entire width of the sheet P is arranged in the sheet conveyance path width direction, and the time difference in which the corners C <b> 1 and C <b> 2 of the sheet P pass through the line sensor 103. Based on this, the skew amount is detected. Further, the shift of the sheet position in the sheet conveyance path width direction is detected based on the position of one side edge of the sheet P on the line sensor 103. In addition, skew correction rollers 203 and 204 that can be driven independently by the drive rollers 201 and 202 are arranged apart from each other in the sheet conveyance path width direction. Then, the sheet conveyance speed of the skew correction rollers 203 and 204 or the frictional force of the rollers 203 and 204 with respect to the sheet is controlled, whereby the skew of the sheet and the positional deviation in the width direction are corrected.
JP 05-286611 A JP 2004-99244 A

  However, the image forming apparatus shown in FIG. 11 exclusively detects the skew amount of the sheet, and cannot detect the deviation of the sheet position in the conveyance path width direction, and can correct the deviation of the sheet position. There was a disadvantage that it was not possible.

  Further, since the image forming apparatus in FIG. 12 detects the skew amount of the sheet based on only the position detection result of the sheet front end corner and performs the skew correction, the skew correction error occurs when the apparatus condition changes. There is a risk that the skew correction cannot be performed with high accuracy.

  Further, as the speed of the image forming apparatus increases, it is required to instantaneously detect the sheet misalignment and the skew feeding amount. However, the conventional image forming apparatus does not sufficiently meet such a demand. .

  SUMMARY OF THE INVENTION An object of the present invention is to correct a sheet position and a skew amount of a sheet as viewed in the sheet conveyance path width direction during sheet conveyance to reduce sheet misalignment and skew, and an image forming apparatus including the sheet conveyance device. Is to provide.

  In order to achieve the above object, a sheet conveying apparatus according to the present invention described in claim 1 detects width direction position detecting means for detecting the position of the sheet in the sheet conveying path width direction, and detects the skew amount of the sheet. A skew amount detection unit, a width direction position correction unit that corrects a sheet position during sheet conveyance so as to reduce a sheet position deviation in the conveyance path width direction based on a detection result of the width direction position detection unit, and a skew amount detection unit And a skew amount correcting means for correcting the skew amount of the sheet during sheet conveyance so as to reduce the skew of the sheet based on the detection result. In the sheet conveying apparatus of the present invention, the width direction position detecting means includes a line sensor arranged at a position extending in the width direction of the conveying path and passing at least one side edge of the sheet. The means includes a plurality of line sensors that extend in the width direction of the conveyance path and are arranged at a position where at least one side edge of the sheet passes, and are arranged at intervals smaller than the sheet length in the sheet conveyance direction. It is characterized by that.

  According to a ninth aspect of the present invention, an image forming apparatus according to the present invention includes the above sheet conveying device.

  According to the present invention, the sheet position in the sheet conveyance path width direction is corrected based on the detection result of the width direction position detection unit. Since the width direction position detection means includes a line sensor that extends in the conveyance path width direction and is disposed at a position where at least one side edge of the sheet passes, the sheet being conveyed passes through the line sensor that forms the width direction position detection means. The sheet position viewed in the conveyance path width direction can be continuously detected. For this reason, when performing the sheet position correction by the width direction position correcting unit, for example, feedback loop control can be performed to set the desired sheet position while detecting the sheet position by the width direction position detecting unit during sheet conveyance. That is, the sheet position in the conveyance path width direction can be corrected with high accuracy.

  In the present invention, a plurality of line sensors, which extend in the conveyance path width direction and are arranged at positions where at least one side edge of the sheet passes, are arranged in the sheet conveyance direction at intervals smaller than the sheet length. The skew amount of the sheet is corrected based on the detection result of the skew amount detecting means. Since the sheet skew amount can be continuously detected while the sheet passes over the plurality of line sensors having such a configuration and arrangement, for example, feedback loop control is performed so as to reduce the skew amount. Skew correction can be performed with high accuracy.

  Further, according to the present invention, an image on a sheet can be obtained by transporting a sheet while satisfactorily performing width direction deviation correction for correcting the sheet position in the sheet transport path width direction and skew correction for correcting the sheet skew amount. Formation can be performed satisfactorily.

  Hereinafter, a sheet conveying apparatus according to a first embodiment of the present invention will be described in detail with reference to FIG.

  FIG. 1 is a schematic plan view showing a sheet conveying apparatus according to a first embodiment of the present invention.

  The sheet conveying apparatus of the present embodiment is installed in various image forming apparatuses, for example, the image forming apparatus of the electrophotographic process shown in FIGS.

  As shown in FIG. 1, the sheet conveying apparatus includes first and second conveying rollers 203 and 204 (conveying) that are in frictional contact with the sheet P and convey the sheet P in a predetermined conveying direction along the sheet conveying path 10. Member) and first and second sheet detection line sensors 104 and 105. The sheet detection line sensors 104 and 105 measure the deviation amount and deviation direction of the sheet P in the conveyance path width direction orthogonal to the sheet conveyance direction, and the skew direction and skew amount of the sheet P with respect to the normal sheet conveyance direction. Yes (width direction position detecting means and skew amount detecting means). For this reason, both of the sheet detection line sensors 104 and 105 are arranged orthogonal to the sheet conveyance direction and extend in the width direction of the conveyance path 10, and are arranged on the same side as viewed from the center in the conveyance path width direction. Has been.

  The conveyance rollers 203 and 204 are arranged to face each other on the sheet conveyance path 10, and the rotation axes of both the conveyance rollers 203 and 204 coincide with one virtual straight line A extending in the conveyance path width direction. Further, the conveyance rollers 203 and 204 convey various sizes of sheets P, and the separation distance L between the conveyance rollers 203 and 204 is based on the width-direction dimension of the smallest size sheet P that is allowed to be conveyed. Is also set to a short value. The conveying rollers 203 and 204 are arranged on the downstream side of the sheet detection line sensors 104 and 105 in the sheet conveying direction, and are directly connected to the pulse motors 201 and 202, respectively, and are independently driven and controlled. ing.

  As described above, the sheet detection line sensors 104 and 105 measure the displacement amount and skew amount of the sheet P, and one side edge of the sheet P (in this embodiment, the right edge of the sheet). Pr) is detected. The position of the sheet side edge, for example, the right edge Pr when passing through the sheet detection line sensors 104 and 105 varies depending on the sheet size, the sheet displacement amount and displacement direction, and the sheet skew amount and skew direction. That is, the position of the right edge of the sheet when the sheet P passes the sensors 104 and 105 varies under the influence of various variables. For this reason, the sheet detection line sensors 104 and 105 are arranged so as to cover the entire area where the right edge position of the sheet can be changed.

  Hereinafter, the arrangement of the sheet detection line sensors 104 and 105 will be further described. As described above, the sheet detection line sensors 104 and 105 extend in the width direction of the conveyance path 10. Each of the line sensors 104 and 105 is arranged in the conveyance path width direction so that the center in the longitudinal direction of the line sensor coincides with the position where the right edge of the sheet (indicated by a broken line in FIG. 1) conveyed in a normal posture passes. It is positioned. Now, the sheet P that is actually transported is most greatly displaced outward in the transport path width direction (lower side in FIG. 1) as compared to the sheet transported in the normal posture, and the slant as shown by the solid line in FIG. When the skew is largest in the row direction, the trailing edge of the right edge of the sheet comes to the outermost side (the lowest side in FIG. 1) when viewed in the conveyance path width direction. This is referred to as the “outermost sheet right edge position”. On the other hand, when the conveyed sheet is most greatly displaced inwardly in the conveyance path width direction and is most skewed in the skew direction opposite to the skew direction shown in FIG. The innermost side when viewed in the width direction of the conveyance path. This is referred to as the “innermost sheet right edge position”.

  In light of the above circumstances, the sheet detection line sensors 104 and 105 have the outer end (the lower end in FIG. 1) coincides with the “outermost sheet right edge position” or the outside as viewed in the conveyance path width direction. It is arranged to be located in the direction. In addition, the sheet detection line sensors 104 and 105 have an inner end (upper end) that coincides with or is positioned at the “innermost sheet right edge position” when viewed in the conveyance path width direction. Has been placed. By arranging the sheet detection line sensors 104 and 105 and setting the sensor lengths in this way, the right edge position of the sheet is detected regardless of changes in various variables such as the sheet size related to the right edge position of the sheet. be able to.

  FIG. 2 is a schematic block diagram illustrating a control system provided in the sheet conveying apparatus of the present embodiment.

  As shown in FIG. 2, the control system includes a skew amount calculation unit 301 and a width direction deviation amount calculation unit 302 connected to the sheet detection line sensors 104 and 105, and a correction connected to both calculation units 301 and 302. And a control unit 303.

  The skew amount calculation unit 301 calculates the skew direction and the skew amount N of the sheet being conveyed based on detection information from the sheet detection line sensors 104 and 105 as described below.

  The width direction deviation amount calculation unit 302 calculates a deviation direction and a width direction deviation amount X of the sheet being conveyed based on detection information from the sheet detection line sensors 104 and 105 as described below.

  The correction control unit 303 has an input side connected to the skew amount calculation unit 301 and the width direction deviation amount calculation unit 302, and an output side connected to the pulse motors 201 and 202. The correction control unit 303 then transmits the skew direction signal and skew amount signal N transmitted from the skew amount calculation unit 301 and the shift direction signal and width direction shift amount signal X transmitted from the width direction shift amount calculation unit 302. Based on the above, the skew and width direction deviation of the sheet being conveyed are corrected (skew amount correction means, width direction position correction means). Specifically, based on the various signals from the calculation units 301 and 302, the correction control unit 303 individually controls drive pulses applied to the pulse motors 201 and 202 to perform width direction deviation correction and skew feeding correction. It is a thing.

  In the calculation of the skew amount N and the determination of the skew direction in the skew amount calculation unit 301, first, detection information is input from the sheet detection line sensors 104 and 105. In the present embodiment, as shown in FIG. 1, the sheet detection line sensors 104 and 105 detect the position of the right edge Pr of the sheet passing through each sensor with reference to the outer end position (lower end position) of each sensor. To do.

In the example of FIG. 1, the first and second sheet right edge positions detected by the first and second sheet detection line sensors 104 and 105 are represented by e and f, respectively. In this case, the skew amount N is
N = ef
Can be obtained.

  The skew amount N may be calculated in consideration of not only the sheet right edge position information e and f but also the sheet length and the arrangement interval L ′ of the sheet detection line sensors 104 and 105.

  As for the skew feeding direction, if the first sheet right edge position e is larger than the second sheet right edge position f and the sign of the skew feeding amount N is positive (N> 0), the “counterclockwise direction” If the sign of the skew amount N is negative (N <0), it is determined to be “clockwise”.

  Then, based on the skew amount N and the skew direction obtained in this way, the correction control unit 303 controls the drive pulses applied to the pulse motors 201 and 202, respectively. As a result, a conveyance speed difference is generated between the conveyance rollers 203 and 204, and the skew of the sheet P being conveyed is corrected.

  Subsequent to the above-described skew correction, width direction deviation correction is performed. Therefore, the width direction deviation amount calculation unit 302 calculates the width direction deviation amount X and determines the deviation direction.

  Therefore, the width direction deviation amount calculation unit 302 first inputs detection information (sheet right edge position information e in the present embodiment) from the sheet detection line sensor 104 after skew correction is completed. The width direction deviation amount calculation unit 302 uses the sheet right edge position information e and the known information representing the center position in the longitudinal direction of the sheet detection line sensor 104 (the normal sheet right edge position d when there is no width direction deviation). A width direction deviation amount X of the sheet P being conveyed is calculated according to the following equation.

X = d−e
As for the deviation direction, if the sheet right edge position e detected by the sheet detection line sensor 104 is smaller than the regular sheet right edge position d and the sign of the deviation amount X is positive (X> 0), “ “Right side”. On the other hand, if the sign of the deviation amount X is negative (X <0), it is determined as “left side”.

  Then, based on the width direction deviation amount X and the deviation direction calculated in this way, the correction control unit 303 controls the drive pulses applied to the pulse motors 201 and 202, respectively. As a result, the correction control unit 303 gives a difference in conveying speed between the conveying rollers 203 and 204 to correct the deviation in the width direction of the sheet being conveyed.

  Hereinafter, the correction control method of the present embodiment will be described with reference to FIG.

  FIG. 3 is a flowchart showing a control procedure of width direction deviation correction and skew feeding correction in the sheet conveying apparatus. In FIG. 3, the width direction deviation allowable value for determining the allowable range of the width direction deviation amount X is represented by Xm, and the tolerance value for determining the skew amount N allowable range is represented by Nm.

  Each time sheet conveyance is started in the sheet conveying apparatus, the control routine in FIG. 3 is started. When the sheet P reaches the second sheet detection line sensor 105 with the progress of sheet conveyance, the sheet right edge position information f from the sensor 105 is converted into the skew amount calculation unit 301 and the width direction deviation amount calculation unit 302. To be supplied. Next, when the sheet P reaches the first sheet detection line sensor 104, sheet right edge position information e from the sensor 104 is supplied to both the arithmetic units 301 and 302. The supply of the position information e and f is continuously performed while the sheet P passes through the sensors 104 and 105.

  In step 401 of FIG. 3, the skew amount calculation unit 301 based on the sheet right edge position information e and f from the sheet detection line sensors 104 and 105 performs the skew direction and skew amount N of the sheet P according to the above-described calculation formula. Is calculated.

  In the next step 402, it is determined by the correction control unit 303 whether or not the skew amount N is within the range of −Nm ≦ N ≦ Nm. Proceed to step 404.

  On the other hand, if the correction control unit 303 determines in step 402 that the skew amount N is not within the allowable range of −Nm ≦ N ≦ Nm, the correction control unit 303 performs skew correction control in step 403. Is called. That is, the correction control unit 303 controls the drive pulse supply to the pulse motors 201 and 202 so that a difference in the conveyance speed according to the skew amount N and the skew direction is given between the conveyance rollers 203 and 204. Skew correction is performed so that the skew amount N becomes zero.

  As described above, the supply of the sheet right edge position information e and f to the skew amount calculation unit 301 is continued while the sheet P passes over the sheet detection line sensors 104 and 105. Therefore, in this control routine, the skew correction control is performed intermittently and continuously, and the control procedure from step 401 to step 403 is repeatedly executed until the skew amount N falls within the above-described allowable range. .

  Thereafter, when it is determined in step 402 that the skew amount N is within the allowable range, the skew correction is terminated, the process proceeds to step 404, and width direction deviation correction is started.

  That is, in step 404, the width direction deviation amount calculation unit 302 calculates the deviation direction and the deviation amount X according to the above-described calculation formula.

  In the next step 405, whether or not the deviation amount X is within the range of −Xm ≦ X ≦ Xm is determined by the correction control unit 303, and if it is determined that the deviation amount X is within the allowable range, Then, the execution of this control routine is terminated.

  On the other hand, if it is determined in step 405 that the deviation amount X is not within the allowable range of −Xm ≦ X ≦ Xm, in step 406, the correction control unit 303 sets the width direction deviation amount X to zero. A conveyance speed difference is given between the conveyance rollers 203 and 204. Specifically, the drive pulses applied to the pulse motors 201 and 202 are controlled. That is, width direction deviation correction control is performed. This correction control is performed by repeatedly executing Step 404 to Step 406 until it is determined that the width direction deviation amount X is within the allowable range. When the width direction deviation amount X falls within the allowable range, the execution of this control routine, that is, the skew correction control and the width direction deviation correction control are ended.

  As described above, according to the present embodiment, the sheet P is made normal by performing drive control of the pulse motors 201 and 202 in accordance with the detection information related to the conveyed sheet P and performing width direction deviation correction and skew correction. Thus, it is possible to carry out proper sheet conveyance.

  In this embodiment, the conveyance speed difference is given between the two conveyance rollers by changing the rotation speed of the conveyance rollers 203 and 204, and thereby the skew correction and the width direction deviation correction are performed. As another method, skew correction and width direction deviation correction can be similarly performed by changing the frictional force between each of the conveying rollers 203 and 204 and the sheet.

  It should be noted that it is not essential to perform the width direction deviation correction after the skew correction is completed. That is, skew correction may be performed after the width direction deviation correction, or both corrections may be performed in parallel.

  Hereinafter, a sheet conveying apparatus according to a second embodiment of the present invention will be described with reference to FIG.

  FIG. 4 is a schematic plan view showing the sheet conveying apparatus according to the present embodiment. As shown in FIG. 4, the basic configuration of the sheet conveying apparatus according to the present embodiment is the same as that of the first embodiment, and therefore, the description of the basic configuration common to that of the first embodiment is omitted. To do.

  In the present embodiment, the conveyance rollers 203 and 204 are disposed on the upstream side of the first sheet detection line sensor 104 and on the downstream side of the second sheet detection line sensor 105. In this respect, the second embodiment is different from the first embodiment in which the conveyance rollers 203 and 204 are disposed on the downstream side of the first and second sheet detection line sensors 104 and 105.

  As described above, the present embodiment is different from the first embodiment only in the positional relationship between the sheet detection line sensors 104 and 105 and the conveyance rollers 203 and 204. Accordingly, the skew correction and the width direction deviation correction are performed. Can be implemented by the same control procedure as in the first embodiment.

  However, in the present embodiment, the width direction deviation amount X is detected by a method different from that in the first embodiment. That is, in the present embodiment, the second information in addition to the detection information e and the known information d from the first sheet detection line sensor 104, which is the basis for the calculation of the width direction deviation amount X in the first embodiment. Detection information f from the sheet detection line sensor 105 is used. Thereby, the accuracy of the sheet right edge position information of the sheet P being conveyed can be improved, and the width direction deviation correction can be performed more appropriately.

  Specifically, in the present embodiment, the width direction deviation amount X is calculated according to the following equation.

X = d- | (ef) / 2 |
Here, d represents a normal sheet right edge position when there is no deviation in the width direction, and e and f represent sheet right edge position information from the first and second sheet detection line sensors 104 and 105.

  Hereinafter, the correction control method of the present embodiment will be described with reference to FIG.

  FIG. 5 is a flowchart showing a control procedure of width direction deviation correction and skew feeding correction in the sheet conveying apparatus of the present embodiment. In FIG. 5, Xm represents a width-direction deviation allowable value that determines the allowable range of the width-direction deviation amount X, and Nm represents an allowable value that determines the allowable range of the skew amount N.

  Now, when sheet conveyance is started in the sheet conveying apparatus, the control routine of FIG. 5 is activated, and sheet right edge position information e, f is sent from the sheet detection line sensors 104, 105 to the skew amount calculation unit as the sheet conveyance proceeds. 301 and the width direction deviation calculation unit 302.

  In step 501 of FIG. 5, the skew amount calculation unit 301 first inputs first and second sheet right edge position data e and f from the first and second sheet detection line sensors 104 and 105. Next, the skew amount calculating unit 301 calculates the skew amount N by subtracting the second sheet right edge position data f from the first sheet right edge position data e. Further, the skew direction is determined based on the sign of the skew amount N.

  In the next step 502, the width direction deviation amount calculation unit 302 inputs the first and second sheet right edge position data e and f, and the normal sheet when there is no width direction deviation from both position data e and f. Based on the right edge position data d, the width direction deviation amount X is calculated from the above-described calculation formula. Specifically, the value obtained by subtracting the second sheet right edge position data f from the first sheet right edge position data e is gradually decreased by 2, and the absolute value of this division result is obtained when there is no deviation in the width direction. The width direction deviation amount X is calculated by subtracting from the normal sheet right edge position data d. Further, the shift direction is determined based on the sign of the width direction shift amount X.

  In step 503, the correction control unit 303 determines whether or not the skew amount N is within the allowable range of −Nm ≦ N ≦ Nm, and the width direction deviation amount X is −Xm ≦ X ≦ Xm. Determine if it is within range. When it is determined that both the skew amount N and the width direction deviation amount X are within the allowable range, the execution of this control routine is terminated.

  On the other hand, in step 503, the correction control unit 303 determines that the skew feeding amount N is not within the allowable range of −Nm ≦ N ≦ Nm, or the width direction displacement amount X is not within the allowable range of −Xm ≦ X ≦ Xm. When it is determined that, step 504 is entered. In step 504, one or both of the skew correction and the width direction deviation correction described in the first embodiment is performed by the correction control unit 303 according to the determination result.

  Thereafter, the control procedure from step 501 to step 504 is repeatedly executed until both the skew feeding amount N and the width direction deviation amount X fall within the allowable range. As a result, when both the skew amount N and the width direction deviation amount X are within the allowable range, the execution of this control routine is terminated.

  Hereinafter, a sheet conveying apparatus according to a third embodiment of the present invention will be described with reference to FIG.

  FIG. 6 is a schematic plan view showing the sheet conveying apparatus according to the present embodiment. The basic configuration of the sheet conveying apparatus according to this embodiment is the same as that of the first and second embodiments, and the description of the configuration common to the three embodiments is omitted.

  In the first and second embodiments, the conveyance rollers 203 and 204 are used as a skew feeding correction conveyance member and a width direction deviation correction conveyance member. In contrast, in the present embodiment, the transport rollers 203 and 204 are exclusively used as the skew correction transport members, and the width direction correction rollers 205 and 206 are newly provided as the width direction deviation correction transport members. ing.

  Each of the width direction correction rollers 205 and 206 has a rotation axis extending obliquely with respect to the sheet conveyance direction, and is driven to rotate around the rotation axis by a stepping motor (not shown). Note that the width direction correction rollers 205 and 206 may be arranged such that their rotation axes extend perpendicular to the sheet conveyance direction.

  As described above, in this embodiment, the transport rollers 203 and 204 are used for skew correction, while the width direction correction rollers 205 and 206 are used for width direction deviation correction. For this reason, the sheet conveying apparatus of the present embodiment has conveying roller moving means (not shown) for moving the conveying rollers 203 and 204 in the approaching / separating direction with respect to the sheet P. The sheet conveying apparatus of the present embodiment further includes correction roller moving means (not shown) that moves the width direction correction rollers 205 and 206 in the approaching / separating direction with respect to the sheet P. In addition, the correction control unit 303 of the present embodiment is configured to drive and control the transport roller moving unit and the correction roller moving unit. More specifically, during skew correction, the conveyance rollers 203 and 204 are pressed against the sheet P and the width direction correction rollers 205 and 206 are separated from the sheet P. During the width direction deviation correction, the conveyance rollers 203 and 204 are separated from the sheet P and the width direction correction rollers 205 and 206 are pressed against the sheet P.

  With the above configuration, the sheet conveying apparatus according to the present embodiment can particularly smoothly and accurately correct the deviation in the width direction.

  Hereinafter, a sheet conveying apparatus according to a fourth embodiment of the present invention will be described with reference to FIG.

  FIG. 7 is a schematic plan view showing the sheet conveying apparatus according to the present embodiment. The basic configuration of the sheet conveying apparatus according to this embodiment is the same as that of the first and second embodiments, and the description of the configuration common to the three embodiments is omitted.

  This embodiment is particularly similar to the second embodiment, but the method for detecting the width direction deviation amount X is different. That is, in the second embodiment, the width direction deviation amount X is detected based on the sheet right edge position information e and f and the known information d indicating the sheet right edge position when there is no width direction deviation. On the other hand, in the present embodiment, the width direction deviation amount X is detected based on the left edge position information and the right edge position information of the sheet P.

  For this reason, the sheet conveying apparatus of the present embodiment is arranged on the left edge side of the sheet conveying path 10 in addition to the first and second sheet detection line sensors 104 and 105 arranged on the right edge side of the sheet conveying path 10. A third sheet detection line sensor 106 is provided.

  The third sheet detection line sensor 106 is arranged symmetrically with the first sheet detection line sensor 104 with respect to the center line of the sheet conveyance path 10. That is, the third sheet detection line sensor 106 is disposed on an extension line in the arrangement direction of the first sheet detection line sensor 104. Further, the left and right edge positions of the sheet P change from the normal positions depending on the sheet size, the sheet width direction deviation, the sheet skew, and the like. Accordingly, the third sheet detection line sensor 106 is disposed at a position that covers the entire variable region of the left edge position of the sheet and has a required length. Then, the third sheet detection line sensor 106 detects the left edge of the sheet P passing through the sensor, and uses the sheet left edge position information g as the skew amount calculation unit 301 and the width direction deviation amount calculation unit of the sheet conveying device. 302 is provided.

  The width direction deviation amount calculation unit 302 inputs the sheet right edge position information e from the first sheet detection line sensor 104 and the sheet left edge position information g from the third sort detection line sensor 106. Then, the width direction deviation amount X of the sheet P is calculated according to the following equation based on both the position information e and g.

X = eg
As described above, in the present embodiment, the positions of the left and right side edges of the sheet P being conveyed are detected by the sheet detection line sensors 104 and 106, and based on the detected sheet left edge position information and sheet right edge position information. A width direction deviation amount X of the sheet P is calculated. Therefore, the width direction deviation amount X can be accurately detected and the width direction deviation can be corrected satisfactorily. In particular, when images are formed on both sides of the sheet P, the image forming position on the first surface side and the image forming position on the second surface side can be matched with high accuracy.

  Since other points are the same as those of the above-described embodiments, description thereof is omitted.

  The description of the preferred embodiment of the present invention is finished as above, but the present invention is not limited to the above embodiment and can be variously modified.

  For example, in each of the above embodiments, the sheet conveying apparatus applied to the image forming apparatus of the electrophotographic process shown in FIGS. 8 to 10 has been described. However, the sheet conveying apparatus of the present invention can be applied to other image forming apparatuses. Of course, the present invention can be applied to various apparatuses other than the image forming apparatus. In the first embodiment and the like, the sheet detection line sensor is arranged so as to detect the right edge of the sheet. However, the left edge of the sheet may be detected.

1 is a schematic plan view showing a sheet conveying apparatus according to a first embodiment of the present invention. 3 is a schematic block diagram illustrating a control system of the sheet conveying apparatus according to the first embodiment. FIG. 6 is a flowchart illustrating a control procedure of width direction deviation correction and skew feeding correction in the sheet conveying apparatus of the first embodiment. It is a schematic plan view which shows the sheet conveying apparatus by the 2nd Embodiment of this invention. 10 is a flowchart illustrating a control procedure of width direction deviation correction and skew feeding correction in the sheet conveying apparatus of the second embodiment. It is a schematic plan view which shows the sheet conveying apparatus by the 3rd Embodiment of this invention. It is a schematic plan view of the sheet conveying apparatus by the 4th Embodiment of this invention. 1 is a schematic configuration diagram of a monochromatic image forming apparatus. 1 is a schematic configuration diagram of a full-color image forming apparatus. 1 is a schematic configuration diagram of a tandem type full-color image forming apparatus. It is a block diagram of the conventional skew correction means. It is a block diagram of the conventional skew and width direction correction means.

Explanation of symbols

1, 1a, 1b, 1c, 1d Photoconductor 2, 2a, 2b, 2c, 2d Charging means 3, 3a, 3b, 3c, 3d Exposure means 4, 4a, 4b, 4c, 4d Developing devices 6, 6a, 6b, 6c, 6d Cleaner 7 Fixing means 51 Intermediate transfer belts 53, 53a, 53b, 53c, 53d Transfer roller 55 Intermediate transfer belt cleaners 56, 57 Secondary transfer rollers 81, 81a, 81b, 81c, 81d Surface potential detection means 101, 102 , 103, 104, 105, 106 Line sensors 201, 202 Stepping motors 203, 204 Conveying rollers 205, 206 Width direction correction roller P Sheet

Claims (9)

The width direction position detecting means for detecting the position of the sheet in the sheet conveying path width direction perpendicular to the sheet conveying direction, the skew amount detecting means for detecting the skew amount of the sheet, and the detection result of the width direction position detecting means. Based on the detection result of the skew amount detection means, the width direction position correction means for correcting the sheet position during sheet conveyance so that the sheet position deviation in the conveyance path width direction is reduced, and the sheet so that the skew of the sheet is reduced In a sheet conveying apparatus having a skew amount correcting means for correcting a skew amount of a sheet during conveyance,
The width direction position detection means includes a line sensor arranged in a position extending in the conveyance path width direction and passing at least one side edge of the sheet,
The skew amount detection means includes a plurality of line sensors that extend in the conveyance path width direction and are disposed at positions through which at least one side edge of the sheet passes, and the plurality of line sensors are arranged in the sheet conveyance direction. The sheet conveying apparatus is characterized in that the sheet conveying apparatus is arranged at an interval narrower than the sheet length.   The width direction position correcting means includes a pair of sheet conveying members that are independently rotationally driven on the same axis extending in the conveying path width direction and convey a sheet, and a difference in conveying speed between the pair of conveying members. The sheet conveying apparatus according to claim 1, wherein the sheet position in the conveying path width direction is corrected.   The width direction position correcting means includes a pair of sheet conveying members that are independently driven to rotate on the same rotation axis extending in the conveying path width direction and convey the sheet, and a paper surface between the pair of conveying members. The sheet conveying apparatus according to claim 1, wherein the sheet position in the conveyance path width direction is corrected by giving a difference in frictional force.   The width direction position correcting unit includes a sheet conveying member that is rotationally driven on a rotation axis extending perpendicularly or obliquely with respect to the sheet conveying direction, and moves the sheet in the conveying path width direction. Item 2. The sheet conveying apparatus according to Item 1.   The sheet conveying apparatus according to claim 1, wherein the width direction position correcting unit corrects the sheet position in the conveying path width direction during a period in which the width direction position detecting unit can detect the sheet.   The skew feeding amount correction means includes a pair of sheet transport members that are driven to rotate independently of each other on the same axis extending in the transport path width direction, and transport a sheet between the pair of transport members. The sheet conveying apparatus according to claim 1, wherein the skew feeding amount of the sheet is corrected by giving the value.   The skew feeding amount correction means includes a pair of sheet conveying members that are driven to rotate independently of each other on the same rotation axis extending in the conveying path width direction, and convey a sheet between the pair of conveying members. The sheet conveying apparatus according to claim 1, wherein the skew feeding amount of the sheet is corrected by giving the frictional force difference.   2. The sheet conveying apparatus according to claim 1, wherein the skew amount correcting means corrects the skew amount of the sheet during a period in which the skew amount detecting means can detect the sheet.   An image forming apparatus comprising the sheet conveying device according to claim 1.

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