JP5987601B2 - Image forming apparatus and adjustment method thereof - Google Patents

Description

  The present invention is suitable for application to monochrome printers, color printers, copiers, multi-function machines, etc. equipped with an adjustment mechanism for adjusting the individual positions of the optical writing unit, registration roller pair, transfer roller and fixing roller. The present invention relates to an image forming apparatus and an adjustment method thereof.

  In recent years, according to image forming apparatuses such as monochrome and color printers, copiers, and multifunction machines, there is an adjustment mechanism that adjusts the position of the conveyance roller with respect to the conveyance direction of the sheet by conveyance rollers such as a pair of registration rollers. Has been implemented. The adjustment mechanism adjusts the position of the registration roller pair so that the conveyance direction of the paper abutted against the registration roller pair matches the conveyance direction of the paper conveyed by the conveyance mechanism (Patent Document 1).

  Here, a paper transport system including an adjustment mechanism for adjusting the position of the transport roller will be described. FIG. 10 is a perspective view showing a configuration example of a paper transport system of the image forming apparatus 200 according to the conventional example. The paper transport system shown in FIG. 10 includes a transport roller 28, a registration roller pair 32, a loop roller 36, a fixing roller 46, and a transfer roller 72 '. The registration roller pair 32 and the loop roller 36 are provided in the registration correction unit 30, and the fixing roller 46 is provided in the fixing unit 40.

  Further, the conveying force of each of the registration roller pair 32, the transfer roller 72 ', and the fixing roller 46 is set such that the fixing roller 46> the registration roller pair 32> the transfer roller 72'. Further, the parallelism of the registration roller pair 32, the transfer roller 72 ', and the fixing roller 46 is maintained. Here, the degree of parallelism refers to the magnitude (error) of straight line or plane deviation from the reference plane (from the measurement glossary). For example, it is a degree indicating whether or not the other roller rotation axis is parallel to one roller rotation axis for accurately transporting the sheet in a direction orthogonal to the roller rotation axis.

  For example, the paper P is transported to the registration correction unit 30 via a transport roller 28 from an upstream paper feeding unit (not shown). In the registration correction unit 30, the front end portion of the sheet P is abutted by the loop roller 36 against the nip portion of the registration roller pair 32 in a pressure contact state. Thereby, for example, a large loop is formed above the registration roller pair 32, and a small loop is formed below the pair of registration rollers 32, and the inclination of the front end portion of the paper P is corrected (registration correction function).

  Also, a misalignment detection unit and a moving unit having a registration roller pair are provided, and before the image formation, the misregistration detection unit detects the misregistration of the sheet after registration correction, and the sheet is detected based on the detected amount of the sheet. A function (registration swing mechanism) is used that corrects misalignment by moving the sheet in a direction perpendicular to the transport direction by a moving unit with a pair of registration rollers (Patent Document 2).

JP 2009-067569 A JP 2007-022680 A

Incidentally, the image forming apparatus 200 having the function of correcting the inclination of the front end of the sheet as found in Patent Document 1 has the following problems.
i. As shown in FIG. 10, since the conveying force of each roller is set differently such as the fixing roller 46> the registration roller pair 32> the transfer roller 72 ′, the registration roller pair 32, the transfer roller 72 ′, and the fixing roller If the parallelism between 46 is broken, the sheet P is conveyed to the image writing position while being inclined. Due to the state that the paper P is inclined, there is a problem that a positional deviation occurs between the image formed by the nip of the transfer roller 72 ′ and the paper P. That is, the image is transferred while being inclined with respect to the paper P.

  iii. Further, according to the image forming apparatus in which the registration rocking mechanism such as that disclosed in Patent Document 2 is mounted, the registration roller pair 32 is separated when the registration roller pair 32 is rocked and then returned to the home position. When the distance for conveying the paper P between the fixing roller 46 and the transfer roller 72 ′ becomes long and the parallelism between the fixing roller 46 and the transfer roller 72 ′ is broken, the paper P conveyed by the fixing roller 46 The inclination of becomes larger. Therefore, there is a problem that the adjustment of the parallelism of the registration roller pair 32 with respect to the transfer roller 72 ′, the adjustment of the parallelism of the fixing roller 46 with respect to the transfer roller 72 ′, and the like must be repeated many times.

  Therefore, the present invention solves the above-described problems, and it is possible to easily and reliably adjust the parallelism of the optical writing unit, the registration roller pair, the fixing roller, and the like with respect to the transfer roller by devising the alignment adjustment method. In addition, an object of the present invention is to provide an image forming apparatus and an adjustment method thereof that can form an image on a sheet without tilting.

In order to solve the above problems, an adjustment method for an image forming apparatus according to claim 1 includes an optical writing unit that writes an image on an image carrier, and an image forming unit that forms an image on the image carrier. A registration correction unit that has a registration roller pair on the upstream side of the image forming unit, abutting the front end of the paper against the registration roller pair to correct the inclination, and an image formed on the image carrier, A transfer roller for transferring to the skew-corrected paper; and a fixing roller having a fixing roller on the downstream side of the image forming unit and fixing the image transferred to the paper ; and the image carrier and the transfer In an adjustment method for an image forming apparatus that maintains parallelism with a roller, a first output step for forming and outputting a predetermined image for viewing the inclination of the image with respect to the paper, and a first output step By the side edge of the paper A first adjustment step of adjusting the parallelism of the registration roller pair with respect to the transfer roller based on a first inclination amount of the image in the sub-scanning direction, and an inclination of the paper after the first adjustment step A second output step for forming and outputting an image for the first writing step, and a second inclination of the image in the main scanning direction with respect to the front end portion of the paper in the second output step. A second adjustment step for adjusting parallelism; a third output step for forming and outputting an image for viewing the inclination of the paper after the second adjustment step; and the paper by the third output step. And a third adjustment step of adjusting the parallelism of the fixing roller with respect to the transfer roller based on a third inclination amount of the image in the main scanning direction with respect to the rear end portion.

According to the adjustment method of the image forming apparatus of the first aspect , the parallelism of the registration roller pair with respect to the transfer roller can be easily and reliably adjusted. Moreover, the parallelism of the optical writing unit can be easily and reliably adjusted with respect to the transfer roller whose parallelism is adjusted with the registration roller pair. In addition, the parallelism between the transfer roller and the fixing roller whose parallelism is adjusted with the optical writing unit can be easily and reliably adjusted. As a result, even if the conveying force is different, such as fixing roller> registration roller pair> transfer roller, an image can be formed without inclination on each of the front end, right end, left end, and rear end of the sheet. Become.

1 is a cross-sectional view illustrating a configuration example of a color copying machine 100 as an embodiment according to the present invention. 3 is a perspective view illustrating a configuration example of an optical writing unit 3. FIG. 3 is a top view illustrating a configuration example of a resist correction unit 30. FIG. 3 is a top view illustrating a configuration example of a fixing unit 40. FIG. (A) And (B) is explanatory drawing which shows the structural example of an output chart, and its image output example. (A)-(C) are top views which show the example of adjustment of the position of the registration correction | amendment part 30. FIG. (A)-(C) are the front views and top views which show the example of adjustment of the position of the optical writing part 3. FIG. 4A to 4C are top views illustrating examples of adjusting the position of the fixing unit 40. FIG. 10 is a flowchart illustrating an example of adjusting the parallelism of the optical writing unit 3, the resist correction unit 30, and the fixing unit 40. FIG. 10 is a perspective view illustrating a configuration example of a sheet conveyance system of an image forming apparatus 200 according to a conventional example.

  Hereinafter, an image forming apparatus and an adjustment method thereof according to an embodiment of the present invention will be described with reference to the drawings. The descriptions in this section do not limit the technical scope described in the claims or the meaning of terms.

  A color copying machine 100 illustrated in FIG. 1 constitutes an example of an image forming apparatus, and includes an optical writing unit 3, a resist correction unit 30, a fixing unit 40, and a transfer roller (including a primary transfer roller 7 and a secondary transfer roller 72). Is provided with an alignment mechanism for adjusting the degree of parallelism, and a color image is formed on a predetermined paper P.

  The image forming apparatus according to the present invention is not limited to the color copying machine 100, and can be applied to monochrome printers, color printers, and composite machines thereof. The color copying machine 100 includes a paper feeding unit 20, a fixing unit 40, a control unit 50, an electrophotographic image forming unit 80, an image reading unit 90, and an automatic document feeding unit. Description of the configuration of the automatic document feeder is omitted for convenience.

  The image reading unit 90 detects image data of a document by irradiating light from a light source onto a document or the like conveyed one by one from an automatic document feeder and receiving the reflected light by a CCD (Charge Coupled Device) 94. To do. The red (R), green (G), and blue (B) (RGB) image data detected by the image reading unit 90 is processed by analog processing, analog / digital (hereinafter referred to as A / D) by an image processing unit (not shown). D) conversion processing, image compression processing, and the like are performed.

  The control unit 50 receives RGB image data Din from an image processing unit or the like. In the control unit 50, the image data Din is yellow (Y), magenta (M), cyan (C) and black ( BK) color conversion to color (YMCK) image data. The image forming unit 80 forms a monochrome or color image on the paper P at the image forming position. In the image forming unit 80, for example, a color toner image is formed based on YMCK-based image data after color conversion.

  The image forming unit 80 includes image forming units 10Y, 10M, 10C, and 10K that share image forming output functions of Y, M, C, and BK colors, respectively. In this example, common function names, for example, Y, M, C, and K indicating colors to be formed are added to the back of the reference numeral 10.

  In the image forming unit 10, a polygon mirror, LPH (LDH) or LDH (LDH) is applied to the photosensitive drum 1 (image carrier) uniformly charged by the charging unit 2 corresponding to each image forming color based on the YMCK image data. An electrostatic latent image is formed by the optical writing unit 3 using a print head or the like. The optical writing unit 3 writes optical information based on YMCK image data on the photosensitive drum 1 through an optical scanning member.

  In addition to the optical writing unit 3, the position of the optical writing unit 3 with respect to the photosensitive drum 1 can be adjusted based on the amount of inclination of the image with respect to the front edge of the paper P in the image forming unit 10 for each image forming color. The second adjustment mechanism 22 is provided. The photosensitive drum 1 is opposed to the primary transfer roller 7 with the intermediate transfer belt 8 interposed therebetween. In this example, the second adjusting mechanism 22 is provided in the optical writing unit 3 so that the position of the optical scanning member with respect to the primary transfer roller 7 can be adjusted.

  The optical writing unit 3 shown in FIG. 2 includes a main body case 61, an optical scanning source 62, a mirror body 63, a lens 64, and a motor 65. The main body case 61 has a plane convex box. In the main body case 61, an optical scanning source 62, a mirror body 63, a lens 64, and a second adjustment mechanism 22 constituting an optical scanning member are configured. A lens adjustment motor 65 is disposed. The optical scanning source 62 generates laser beam light 13 having an intensity based on YMCK image data and scans the photosensitive drum 1 with the laser beam light 13 in a line (scanning line) via a mirror 63 and a lens 64. Then, exposure is performed.

  In this example, a motor 65 for adjusting the posture of the lens 64 is provided. For example, one (right back) of the lens 64 has a hinge structure, and the other (left back) has a lifting structure, and the lens 64 can be adjusted in the vertical direction via the motor 65. In the figure, when X is the main scanning direction (width direction of the paper P), Y perpendicular to X is the sub-scanning direction (paper P transport direction), and Z perpendicular to Y is the lens adjustment direction, the lens 64 Is lifted in the Z direction, the position of the lens 64 can be adjusted so that the direction of the rotation axis of the primary transfer roller 7 and the optical scanning direction of the scanning line by the optical writing unit 3 are parallel to each other. (Adjustment of parallelism of the optical writing unit 3 with respect to the primary transfer roller 7).

  The above-described electrostatic latent image is developed by the developing device 4 corresponding to each image forming color. The color toner image formed on the photosensitive drum 1 by performing such charging, exposure and development operates the primary transfer roller 7 corresponding to the photosensitive drum 1 for Y, M, C, and BK colors. Then, the image is transferred to the intermediate transfer belt 8 (image carrier) (primary transfer). The color toner images are superimposed on the intermediate transfer belt 8. The color toner image superimposed here is transferred onto the paper P by the secondary transfer roller 72. The secondary transfer roller 72 is positioned with respect to the primary transfer roller 7.

  Below the image forming unit 80, a paper feeding unit 20, a registration correction unit 30, and a paper reversing unit 60 (ALU) are provided. The paper feed unit 20 includes paper feed trays 20A, 20B, 20C and the like. Each of the paper feed trays 20A, 20B, 20C accommodates a paper P of a predetermined size.

  The paper feed trays 20A, 20B, and 20C are provided with a pickup roller 23 that picks up the paper P from each paper feed tray, and a separating roller 24 that prevents double conveyance of the paper P in each paper feed tray. Conveying rollers 26 and 28 are provided on the downstream side of the roller 24. In this example, the color copying machine 100 can be connected to a large paper feeder (PFU) for feeding paper P in addition to the paper feeder 20.

  In the paper feeding unit 20 described above, the operation display unit (not shown) takes out the paper P by the pick-up roller 23 such as the paper feeding tray 20A selected from each of the paper feeding trays 20A, 20B, 20C, etc. The sheet P is conveyed to the registration correction unit 30 via the conveyance rollers 26 and 28 and the like.

  The resist correction unit 30 is provided in the conveyance path between the secondary transfer roller 72 and the conveyance roller 28. The registration correction unit 30 includes a registration roller pair 32, a loop roller 36, a registration swinging unit 38 (see FIG. 3), and the like that can be pressed and separated from each other. The first detection unit 11 is disposed immediately upstream of the image forming unit 80 and downstream of the registration roller pair 32.

  In the registration correction unit 30, the inclination (skew) of the paper P conveyed to the registration roller pair 32 is corrected (corrected) by the abutment of the front end portion of the paper P against the registration roller pair 32 by the loop roller 36 ( (Registration correction function). In the registration correction unit 30 after the inclination of the paper P is corrected, the deviation amount of the paper P with respect to the edge reference position is detected by the first detection unit 11, and a deviation detection signal is output to the control unit 50. .

  The control unit 50 controls the registration rocking unit 38 and moves the position in a direction perpendicular to the conveyance direction of the paper P while the paper P is sandwiched between the registration roller pairs 32, thereby adjusting the deviation amount of the paper P. The deviation is corrected in the decreasing direction (resist swing correction). The sheet P is conveyed to the secondary transfer roller 72 at a predetermined timing even while the registration is swinging. The secondary transfer roller 72 transfers the color image carried on the intermediate transfer belt 8 onto a predetermined paper P.

  The registration correction unit 30 includes a first adjustment mechanism 31 that adjusts the position of the registration roller pair 32 with respect to the secondary transfer roller 72. As shown in FIG. 3, the first adjustment mechanism 31 has a rotation shaft portion 33 with respect to the apparatus main body portion 101, and the registration correction portion 30 is moved leftward or rightward (clockwise / It can be rotated counterclockwise). For example, in the conveyance direction of the paper P, the rotation shaft portion 33 is located at a position corresponding to the paper center Pc (the center of gravity of the registration correction unit 30) or near the end reference position Ps of the paper P (on the registration correction unit 30 or above). Lower part: Arranged in a dotted circle with a dot mark).

  At the time of alignment adjustment, the rotation with respect to the rotation shaft portion 33 is free, but at the end of the alignment adjustment, the rotation of the rotation shaft portion 33 is constrained and the attachment position of the registration correction unit 30 with respect to the secondary transfer roller 72. Is fixed by engaging members such as screws, bolts and nuts. In addition, the rotating shaft part 33 may be provided with a long hole part that allows movement in the vertical direction so as to be rotatable in the front-rear direction. In addition to the tilt adjustment in the left or right direction, the amount of movement in the vertical direction (main scanning direction X) can be adjusted.

  In this example, a frame-shaped frame image for detecting the inclination of the paper P is formed by the image forming unit 80, and the inclination amount θ1 (first inclination amount) of the image in the sub-scanning direction Y with respect to the side edge of the paper P. ), The position (parallelism) of the registration correction unit 30 with respect to the secondary transfer roller 72 can be adjusted by the first adjustment mechanism 31 (see FIG. 6B).

  The toner image transferred onto the predetermined paper P is fixed by the fixing unit 40. The fixing unit 40 is provided on the downstream side of the image forming unit 80, and includes a main body case 41, a pressure roller 44, and a heating roller 45 (hereinafter collectively referred to as a fixing roller 46) shown in FIG. The fixing unit 40 heat-fixes the color toner image transferred onto the paper P by the secondary transfer roller 72 by applying heat through the fixing roller 46.

  The fixing unit 40 includes a third adjustment mechanism 43 that can adjust the position of the fixing unit 40 with respect to the secondary transfer roller 72 based on the amount of inclination of the image in the main scanning direction with respect to the trailing edge of the paper P. . As shown in FIG. 4, the third adjustment mechanism 43 has a rotation shaft portion 42 for the apparatus main body 101, and the fixing portion 40 is moved leftward or rightward (clockwise / counterclockwise) with respect to the rotation shaft portion 42. It can be rotated clockwise. For example, in the conveyance direction of the paper P, the rotation shaft portion 42 is located at a position corresponding to the paper center Pc (the center of gravity of the fixing unit 40) or near the end reference position Ps of the paper P (upper or lower portion of the fixing unit 40: It is arranged at a portion indicated by a dot mark in a broken line circle).

  At the time of alignment adjustment, the rotation with respect to the rotation shaft portion 42 becomes free, but at the end of the alignment adjustment, the rotation with respect to the rotation shaft portion 42 is restrained and the fixing portion 40 with respect to the secondary transfer roller 72 is restrained. The mounting position is fixed by an engaging member such as a screw, bolt or nut. In addition, the rotating shaft part 42 may be provided with a long hole part that allows movement in the vertical direction so as to be rotatable in the front-rear direction. In addition to the tilt adjustment in the left or right direction, the amount of movement in the vertical direction (main scanning direction X) can be adjusted. As a result, a color image based on the image data Din can be formed on the predetermined paper P.

  A cleaning unit 6 is provided on the lower left side of each of the above-described photosensitive drums 1 corresponding to the photosensitive drums 1 for Y, M, C, and K colors. It operates to remove (clean) the remaining toner agent. A cleaning unit 6A is provided on the upper left side of the intermediate transfer belt 8 and operates to clean the toner agent remaining on the intermediate transfer belt 8 after transfer.

  The color copying machine 100 is provided with a duplex printing mode and a paper reversing unit 60 (ALU). The paper reversing unit 60 is disposed above the paper feed tray 20A, and automatically reverses the front and back of the paper P after the surface image is formed in the duplex printing mode.

  When the duplex printing mode is set, the sheet P after the front surface image is formed is conveyed from the fixing unit 40 to the sheet reversing unit 60. In the paper reversing unit 60, the front and back of the paper P are automatically reversed. The reversed paper P is fed again to the image forming unit 80. Thus, the color copying machine 100 is configured.

  Next, with reference to FIGS. 5 to 9, examples of adjusting the parallelism of the optical writing unit 3, the resist correction unit 30, and the fixing unit 40 with respect to the secondary transfer roller 72 regarding the adjustment method of the image forming apparatus according to the present invention. Will be described. In this example, the parallelism among the photosensitive drum 1, the intermediate transfer belt 8, the primary transfer roller 7, and the secondary transfer roller 72 of the image forming unit 80 is maintained. The rotation axis of the secondary transfer roller 72 and the rotation of the registration roller pair 32 are adjusted by adjusting the position of the registration correction unit 30, the position of the optical writing unit 3, and the position of the fixing unit 40 with respect to the secondary transfer roller 72. It is assumed that the parallelism is adjusted so that the axis, the scanning line by the optical scanning source 62, the mirror 63, and the lens 64 and the rotation axis of the fixing roller 46 are parallel to each other.

  According to the configuration example of the output chart Cout shown in FIG. 5A, the frame image G based on the output chart Cout is formed on the paper P selected by the operation display unit (not shown). The output chart Cout is a target image for viewing (determining) the inclination of the image with respect to the paper P, and is an output image expected by the control unit 50.

  In this example, a rectangular (rectangular) frame image G is formed as the output chart Cout. A dimension “a” in the drawing is a length from each side edge of the paper P having a predetermined paper size to the long side of the frame image G. The dimension b in the figure is the length from the front end and the rear end of the paper P to each short side of the frame image G. Of course, if each intersection of the frame image G is 90 ° (right angle), the length from the left and right side edges of the paper P to the long side of the frame image G, or the frame image from the front edge and the rear edge of the paper P You may set a different dimension about the length to the upper and lower short sides of G.

  The control unit 50 controls the image forming unit 80 so that the center Gc of the frame image G coincides with the paper center Pc. According to the image output example of the output chart Cout shown in FIG. 5B, a rectangular frame image G is formed on the selected paper P. In this example, when the parallelism of the optical writing unit 3, the resist correction unit 30, and the fixing unit 40 is optimally adjusted, the frame image G is not inclined with respect to the paper P, and the frame image G The center Gc is formed to coincide with the paper center Pc.

  In this example, regarding the adjustment of the parallelism of the optical writing unit 3, the registration correction unit 30, and the fixing unit 40, the position of the registration correction unit 30 is adjusted by the inclination amount θ1 in the sub-scanning direction Y, and then the front end portion of the paper P It is assumed that the position of the optical writing unit 3 is adjusted first by the inclination amount θ2 and the position of the fixing unit 40 is finally adjusted by the inclination amount θ3 of the rear end.

  Using these as conditions for adjusting the parallelism of the optical writing unit 3, the resist correction unit 30, and the fixing unit 40 with respect to the secondary transfer roller 72 (primary transfer roller 7), first, the image forming unit 80 is set in step ST1 shown in FIG. By operating, a frame image G based on the output chart Cout as shown in FIG. 5A is output (first output step; see FIG. 5B).

  Next, looking at the frame image G obtained in the first output step, in step ST2, it is determined whether or not there is an inclination amount θ1 (first inclination amount) of the frame image G in the sub-scanning direction Y. For example, according to the example of adjusting the position of the registration correction unit 30 as shown in FIG. 6A, the main scanning direction X perpendicular to the sheet center Pc in the conveyance direction (sub-scanning direction Y) of the sheet P is used. This is a case where the registration correction unit 30 is attached by being inclined clockwise by the inclination amount θ1.

  When the frame image G is formed by the image forming unit 80 on the paper P after the registration correction by the registration correction unit 30 in such an attached state, as shown in FIG. An inclined frame image G is output. In the registration correction, the front end portion of the paper P is pressed against the nip portion of the registration roller pair 32 in the conveyance direction of the paper P, the front end portion of the paper P is corrected so as to be orthogonal to the clamping direction, and the inclination of the paper P is corrected. Is done.

  In this example, since the registration correction is performed by the registration correction unit 30 that is attached to the main scanning direction X by the inclination amount θ1 in the clockwise direction, the side end portion and the frame image near the front end portion of the paper P are displayed. The distance to the long side of G is shortened (a−α). Further, the distance from the side end portion near the rear end portion of the paper P to the long side of the frame image G is long (a + α).

  Since the sheet P at the sheet center Pc inclined clockwise by the inclination amount θ1 with respect to the image center Gc is conveyed to the secondary transfer roller 72, the sheet P is inclined with respect to the sheet P as shown in FIG. This is an example in which the frame image G has been formed. That is, with respect to the rotation axis of the secondary transfer roller 72 (parallel to the main scanning direction X), the rotation axis of the registration roller pair 32 of the registration correction unit 30 is inclined clockwise by the inclination amount θ1. And the registration roller pair 32 are not maintained in parallel. In such a state, the attachment position of the registration correction unit 30 may be adjusted so that the inclination amount θ1 in the sub-scanning direction Y becomes zero.

Therefore, when the inclination amount θ1 described above is present, in step ST3, the position of the registration correction unit 30 is adjusted so as to eliminate the inclination amount θ1 of the frame image G in the sub-scanning direction Y (first adjustment step). In this example, as shown in FIG. 6C, the first correction mechanism 31 may rotate the registration correction unit 30 leftward (counterclockwise) by an inclination amount θ1. Here, if the dimensional difference in the main scanning direction X is α and the separation distance between two long sides in the sub-scanning direction Y is β, the inclination amount θ1 is θ1 = tan ⁻¹ α / β.

  As shown in FIG. 6C, by the rotation with the inclination amount θ1 being zero, as shown in FIG. 6C, the distance from the side edge near the front edge of the paper P to the long side of the frame image G, or the rear edge of the paper P The distance from the side end close to the part to the long side of the frame image G is the dimension a expected by the control unit 50. Thus, the parallelism of the registration correction unit 30 (registration roller pair 32) with respect to the secondary transfer roller 72 is determined based on the inclination amount θ1 in the sub-scanning direction Y of the side edge of the frame image G formed by the image forming unit 80. You can adjust it.

  When there is no inclination amount θ1 of the frame image G in the sub-scanning direction Y, the process proceeds to step ST5. Thereafter, in step ST4, the image forming unit 80 is operated to output a frame image G based on the output chart Cout (second output step). Then, by looking at the frame image G obtained in the second output step, it is determined in step ST5 whether or not there is an inclination amount θ2 (second inclination amount) of the frame image G at the front end with respect to the paper P. For example, according to the adjustment example of the position of the optical writing unit 3 shown in FIG. 7A, the light is incident by an inclination amount θ2 with respect to the main scanning direction X orthogonal to the rotation direction of the photosensitive drum (sub-scanning direction Y). This is a case where the writing unit 3 is attached to be inclined counterclockwise.

  When the frame image G is formed by the image forming unit 80 on the paper P after registration correction by the optical writing unit 3 in such an attached state, as shown in FIG. A tilted frame image G is output. In this example, since the frame image G is written on the photosensitive drum 1 by the optical writing unit 3 that is attached to the main scanning direction X by an inclination amount θ2 in the counterclockwise direction, the front end portion of the paper P The distance from one of these to the short side of the frame image G is shortened (b−α ′). Further, the distance from the other front end of the paper P to the short side of the frame image G is long (b + α ′).

  Although the paper center Pc coincides with the image center Gc, the optical writing unit 3 inclined in the counterclockwise direction by the inclination amount θ2 passes through the photosensitive drum 1 and the intermediate transfer belt 8 (see FIG. 1). In this example, since the frame image G is transferred by the secondary transfer roller 72, a frame image G having a front end inclined with respect to the paper P as shown in FIG. 7B is formed.

  That is, the position of the lens 64 of the optical writing unit 3 is inclined counterclockwise by the inclination amount θ2 with respect to the rotation axis of the primary transfer roller 7 (parallel to the main scanning direction X). The parallelism with the writing unit 3 is not maintained. In such a state, the position of the optical writing unit 3 may be adjusted so that the inclination amount θ2 in the main scanning direction X becomes zero.

  Therefore, if there is an inclination amount θ2 of the frame image G at the front end with respect to the paper P, the position of the optical writing unit 3 is adjusted by the inclination amount θ2 of the frame image G at the front end in step ST6 (second adjustment step). . In this example, the second adjustment mechanism 22 moves the lens 64 to the right side (clockwise) so that the left back side of the lens 64 shown in FIG. 3 is raised (lifted) in the Z direction via the motor 65. It is only necessary to rotate by the inclination amount θ2. By rotating the tilt amount θ2 to zero, the direction of the rotation axis of the primary transfer roller 7 and the main scanning direction X of the scanning line by the optical writing unit 3 are parallel to each other, as shown in FIG. Both the distance from one of the front end portions of the paper P to the short side of the frame image G and the distance from the other front end portion of the paper P to the short side of the frame image G are both the dimension b expected by the control unit 50. Become.

Here, if the dimensional difference in the sub-scanning direction Y is α ′, and the separation distance between two short sides in the main scanning direction X is β ′, the inclination amount θ2 is θ2 = tan ⁻¹ α ′ / β ′. It becomes. Thus, after the registration correction unit 30 adjusts the inclination of the image in the sub-scanning direction Y with respect to the side edge of the paper P, the front end of the frame image G formed by the image forming unit 80 in the main scanning direction X is adjusted. The parallelism of the optical writing unit 3 (optical scanning member) with respect to the primary transfer roller 7 can be adjusted based on the inclination amount θ2.

  When there is no inclination amount θ2, the process proceeds to step ST8. In step ST7, the image forming unit 80 is operated to output a frame image G based on the output chart Cout (third output step). Thereafter, the frame image G obtained in the third output step is viewed, and in step ST8, it is determined whether or not there is an inclination amount θ3 (third inclination amount) of the frame image G at the rear end with respect to the paper P. For example, according to the adjustment example of the position of the fixing unit 40 shown in FIG. 8A, the inclination amount θ3 with respect to the main scanning direction X orthogonal to the sheet center Pc in the conveyance direction (sub-scanning direction Y) of the sheet P. This is the case where the fixing unit 40 is attached while being inclined counterclockwise.

  When the paper P after image formation is nipped by the fixing roller 46 immediately before fixing in the fixing unit 40 in such an attached state, a frame image tilted with respect to the paper P as shown in FIG. G is output. Even in the nip by the fixing roller 46, the front end portion of the sheet P is pressed against the fixing roller 46 (the nip portion between the pressure roller 44 and the heating roller 45) in the conveyance direction of the sheet P, and the sheet P is orthogonal to the nipping direction. The front edge of is corrected.

  In this example, since the nip is performed by the fixing roller 46 by the fixing unit 40 that is attached to the main scanning direction X by the inclination amount θ3 in the clockwise direction, the influence is exerted on the rear end portion of the paper P. The distance from one of the rear end portions to the short side of the frame image G is shortened (b−α ″). The distance from the other rear end portion of the paper P to the short side of the frame image G is short. It is longer (b + α ″).

  Since the sheet P of the sheet center Pc inclined in the counterclockwise direction by the inclination amount θ3 with respect to the image center Gc is conveyed to the secondary transfer roller 72, the rear end of the sheet P as shown in FIG. This is an example in which a frame image G tilted with respect to the portion has been formed. That is, with respect to the rotation axis of the secondary transfer roller 72 (parallel to the main scanning direction X), the rotation axis of the fixing roller 46 of the fixing unit 40 is inclined counterclockwise by the inclination amount θ3. This is a state in which the parallelism with the fixing roller 46 is not maintained. In such a state, the attachment position of the fixing unit 40 may be adjusted so that the inclination amount θ3 in the sub-scanning direction Y becomes zero.

Accordingly, when the tilt amount θ3 is present, the position of the fixing roller 46 is adjusted by the tilt amount θ3 of the frame image G at the rear end in step ST9 (third adjustment step). In this example, as shown in FIG. 8C, the fixing unit 40 may be rotated rightward (clockwise) by the tilt amount θ3 by the third adjustment mechanism 43. Here, when the dimensional difference in the main scanning direction X is α ″ and the separation distance between two short sides in the sub-scanning direction Y is β ″, the inclination amount θ3 is θ3 = tan ⁻¹ α ″ / β ″. It becomes.

  As shown in FIG. 8C, the rotation with the tilt amount θ3 set to zero causes the distance from one of the trailing edge of the paper P to the short side of the frame image G, and the other of the trailing edge of the paper P. And the distance to the short side of the frame image G is the dimension b expected by the control unit 50. Thus, after the optical writing unit 3 adjusts the inclination of the main scanning direction X of the image with respect to the front end of the paper P, the inclination of the rear end of the frame image G formed by the image forming unit 80 in the sub-scanning direction Y. Based on the amount θ3, the parallelism of the fixing unit 40 (fixing roller 46) with respect to the secondary transfer roller 72 can be adjusted.

  Thereafter, in step ST10, the image forming unit 80 is operated to output a frame image G based on the output chart Cout. In addition, when there is no inclination amount θ3 of the frame image G at the rear end in the above-described step ST8, and after outputting the frame image G based on the output chart Cout in step ST10, the output of the frame image G corresponds to step ST11. To determine whether or not to finish the adjustment process. When the frame image G is formed with no inclination on the paper P, the parallelism adjustment processing of the optical writing unit 3, the resist correction unit 30, and the fixing unit 40 ends. When the frame image G is inclined with respect to the paper P, the process returns to FIG. 1 and the above-described parallelism adjustment processing of the optical writing unit 3, the resist correction unit 30, and the fixing unit 40 is continued.

  In this way, according to the color copying machine 100 as the embodiment, the frame image G for viewing the inclination of the paper P is formed and output, and the inclination amount θ1 of the frame image G with respect to the paper P in the sub-scanning direction Y is output. And the position of the resist correction unit 30 with respect to the secondary transfer roller 72 is adjusted based on the detected tilt amount θ1.

  With this configuration, the parallelism of the registration roller pair 32 with respect to the secondary transfer roller 72 can be easily and reliably adjusted. As a result, even if the conveying force is different, such as the registration roller pair 32> secondary transfer roller 72, etc., an image can be formed without tilting in parallel with the side edge in the conveying direction of the paper P.

  Further, according to the color copying machine 100, the inclination amount θ2 in the main scanning direction X of the frame image G with respect to the front end portion of the paper P is detected, and the position of the optical writing unit 3 with respect to the photosensitive drum 1 based on the inclination amount θ2. Thus, the parallelism of the optical scanning member with respect to the primary transfer roller 7 can be easily and reliably adjusted. As a result, an image can be formed in parallel with the front end portion of the paper P without inclination.

  According to the color copying machine 100, the inclination amount θ3 in the main scanning direction X of the frame image G with respect to the rear end portion of the paper P is detected, and the position of the fixing unit 40 with respect to the two transfer rollers 72 is adjusted based on the inclination amount θ3. As a result, the parallelism between the secondary transfer roller 72 and the fixing roller 46 can be easily and reliably adjusted. As a result, even if the conveying force is different, such as the fixing roller 46> the registration roller pair 32> the secondary transfer roller 72, an image can be formed in parallel with the rear end portion of the sheet without inclination. In addition, the toner image can be fixed on the sheet P by the fixing unit 40 whose parallelism is adjusted with respect to the secondary transfer roller 72.

  According to the color copying machine 100, the parallelism, which is the position of the registration correction unit 30 with respect to the secondary transfer roller 72, the position of the optical writing unit 3, and the position of the fixing unit 40, can be adjusted. The axis, the scanning line by the optical scanning member (in the case of the scanning axis of the optical scanning source, orthogonal rather than parallel) and the rotational axis of the fixing roller 46 are aligned with the rotational axis of the secondary transfer roller 72 serving as a reference in parallel with high accuracy. be able to. As a result, the alignment adjustment of the registration correction unit 30, the optical writing unit 3, and the fixing unit 40 can be performed without rework.

  According to the color copying machine 100, the registration correction unit 30 includes the detection unit 11 and the registration swing unit 38, and after the inclination of the paper P is corrected, the detection unit 11 causes the deviation amount of the paper P relative to the edge reference position. The registration roller pair 32 holding the paper P is moved based on the deviation detection signal. With this configuration, it is possible to correct the deviation of the sheet P immediately before the sheet P is conveyed to the image forming unit 80 (registration swing mechanism).

  Further, in the color copying machine 100, the second detection unit 12 is disposed on the upstream side of the registration correction unit 30, for example, on the conveyance path connected to the large sheet feeding device, and the sheet P fed from the large sheet feeding device is disposed. It is also possible to detect the deviation of the. Of course, the second detection unit 12 ′ may be arranged in the reverse conveyance path of the paper reversing unit 60 to detect the deviation of the paper P that is reversed by the paper reversing unit 60 in the duplex printing mode (see FIG. 1).

  According to the color copying machine 100 including the detection units 12 and 12 ', the detection units 12 and 12' detect the deviation amount of the paper P with respect to the edge reference position in advance and acquire and place the deviation detection signal. After correcting the inclination of the paper P by the registration roller pair 32, the image writing position is corrected based on the deviation detection signal. With this configuration, it is possible to correct the deviation of the sheet P immediately before the sheet P is conveyed to the image forming unit 80 without using the registration swing mechanism.

  Further, according to the adjustment method of the color copying machine 100, the parallelism of the registration roller pair 32 with respect to the secondary transfer roller 72 can be easily and reliably adjusted. In addition, the parallelism of the optical writing unit 3 can be easily and reliably adjusted with respect to the secondary transfer roller 72 whose parallelism is adjusted with the registration roller pair 32. Further, the parallelism between the secondary transfer roller 72 and the fixing roller 46 whose parallelism is adjusted with the optical writing unit 3 can be easily and reliably adjusted. Thus, even if the conveying force is different, such as the fixing roller 46> the registration roller pair 32> the secondary transfer roller 72, etc., there is no inclination with respect to each of the front end portion, right end portion, left end portion, and rear end portion of the paper P. An image can be formed.

  Regarding the adjustment of the parallelism of the registration correction unit 30, the optical writing unit 3, and the fixing unit 40, the optical writing unit 3 is first adjusted by the inclination amount θ2 of the front end portion of the paper P, and then the inclination in the sub-scanning direction Y is adjusted. When the registration correction unit 30 is adjusted by the amount θ1 and finally the fixing unit 40 is adjusted by the inclination amount θ3 of the rear end, the frame image G is not formed on the paper P with good reproducibility, and the adjustment is poor. Has been confirmed to fall into.

  In addition, regarding the second adjustment mechanism 22, the case where the lens 64 provided in the optical writing unit 3 is raised and lowered to the pinpoint has been described, but the present invention is not limited to this. Like the first adjustment mechanism 31 and the third adjustment mechanism 43, the position of the optical writing unit 3 is adjusted to adjust the position of the entire adjustment target (unit units such as the registration correction unit 30 and the fixing unit 40). The unit 101 may be adjusted for each unit.

  Regarding the first adjustment mechanism 31 and the third adjustment mechanism 43, the case where the position of the corresponding registration correction unit 30 or fixing unit 40 is adjusted in units of the apparatus main body unit 101 has been described, but the present invention is not limited thereto. There is nothing. Like the second adjustment mechanism 22, the position of the rotation axis of the corresponding registration roller pair 32 and the rotation axis of the fixing roller 46 is pinpointed so as to adjust the position of the specific member (lens 64) within the adjustment target. You may make it adjust.

  Further, regarding the determination of the inclination of the paper P in steps ST2, 5, and 8 shown in FIG. 9, the output image is read by the image reading unit 90, and the frame image G of the output chart Cout expected by the control unit 50 is read. However, the actual frame image G may be compared to determine the correlation. Of course, the tilt amounts θ1, θ2, and θ3 required for manual adjustment may be calculated and displayed on an operation display unit (not shown). If the first adjustment mechanism 31, the second adjustment mechanism 22, and the third adjustment mechanism 43 are configured by introducing a drive unit that can be controlled by the control unit 50, a fully automatic alignment mechanism can be configured.

1Y, 1M, 1C, 1K Photosensitive drum (image carrier)
2Y, 2M, 2C, 2K Charging unit 3Y, 3M, 3C, 3K Optical writing unit 4Y, 4M, 4C, 4K Developing device 7 Primary transfer roller 8 Intermediate transfer belt (image carrier)
10Y, 10M, 10C, 10K Image forming unit (image forming unit)
DESCRIPTION OF SYMBOLS 11 1st detection part 12 2nd detection part 20 Paper feed part 22 2nd adjustment mechanism 30 Registration correction part 31 1st adjustment mechanism 32 Registration roller pair 36 Loop roller 40 Fixing part 43 3rd adjustment mechanism 46 Fixing Roller 50 control unit
60 Paper reversing unit 72 Secondary transfer roller 80 Image forming unit 100 Color copier (image forming apparatus)

Claims (1)

An image writing unit for writing an image on the image carrier, an image forming unit for forming an image on the image carrier, and a registration roller pair on the upstream side of the image forming unit. A registration correction unit that abuts the front end of the paper to correct the inclination, a transfer roller that transfers the image formed on the image carrier onto the paper whose inclination is corrected, and a fixing roller on the downstream side of the image forming unit A fixing unit that fixes the image transferred to the paper, and an adjustment method for an image forming apparatus in which parallelism between the image carrier and the transfer roller is maintained .
A first output step of forming and outputting a predetermined image for viewing the inclination of the image with respect to the paper;
A first adjustment step of adjusting the parallelism of the registration roller pair with respect to the transfer roller based on a first inclination amount of the image in the sub-scanning direction with respect to the side edge portion of the paper in the first output step;
A second output step of forming and outputting an image for viewing the inclination of the paper after the first adjustment step;
A second adjustment step of adjusting the parallelism of the optical writing unit with respect to the image carrier based on a second inclination amount of the image in the main scanning direction with respect to the front end portion of the paper in the second output step;
A third output step of forming and outputting an image for viewing the inclination of the paper after the second adjustment step on the paper;
An image forming apparatus comprising: a third adjustment step of adjusting a parallelism of the fixing roller with respect to the transfer roller based on a third inclination amount of the image in the main scanning direction with respect to the rear end portion of the sheet in the third output step. Adjustment method.

Images