JP5907618B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus that detects an adjustment toner image on a conveyance body with an optical sensor and adjusts the position of an image formed on the image carrier in the main scanning direction. The present invention relates to control that increases the positional accuracy of a toner image on an image carrier in the main scanning direction excluding the influence.

  A so-called tandem-type image in which a plurality of image forming units form toner images of different colors on an image carrier and sequentially transfer them to a recording medium on a conveyance body (intermediate transfer body) or conveyance body (recording material conveyance body). Forming devices are widely used. In a tandem type full-color image forming apparatus, when different primary color toner images formed on different image carriers are displaced in the rotation direction of the conveyance body, a color shift occurs in the sub-scanning direction, and the different primary color toner images are transferred to the conveyance body. Shift in the width direction occurs in the main scanning direction.

  In a tandem type full-color image forming apparatus, in order to eliminate color misregistration in the main scanning direction, a main scanning position that adjusts the relative positions in the main scanning direction of toner images formed on a plurality of image carriers during non-image formation The alignment mode can be executed (Patent Document 1).

  In Patent Document 1, a plurality of color registration toner images each having an edge inclined obliquely with respect to a scanning line are formed and transferred to a conveyance body. Then, each color registration toner image is detected using an optical sensor arranged at a predetermined position on the conveyance body, and the image on the scanning line of each image carrier is offset so as to cancel the detected deviation amount. The write start position is adjusted.

  Japanese Patent Application Laid-Open No. 2004-228561 discloses control for eliminating color misregistration by accurately superimposing toner images formed by a plurality of image forming units in the sub-scanning direction. In the first image forming unit, a magnetic recording scale is formed on the conveyance body corresponding to the scanning line of the toner image on the first image carrier, and in the second image forming unit, the second image is formed on the magnetic recording scale of the conveyance body. The second image carrier is controlled so that the scanning lines of the carrier are aligned one to one.

  In Patent Document 3, electrostatic image graduations formed on an image carrier and a carrier corresponding to scanning lines for image writing are respectively detected by an antenna-type potential sensor to form a toner image on the carrier. Control for superimposing the toner images on the second image carrier is shown.

JP 2008-77016 A JP 2009-134264 A JP 2012-18310 A

  As disclosed in Patent Document 1, when the edge of the registration alignment toner image on the conveyance body is read with an optical sensor and the position of the edge in the main scanning direction is detected, the circumference of the conveyance body is detected. The fluctuation in speed becomes the detection error of the position of the edge in the main scanning direction as it is. The fluctuation in the peripheral speed of the carrier is a shift in the timing at which the registration alignment toner image passes through the detection position of the optical sensor. The distance distributed in the direction becomes the detection error of the position in the main scanning direction.

  According to the present invention, even if a large speed fluctuation occurs in the conveyance body, the position of the toner image formed on the plurality of image carriers in the main scanning direction can be precisely adjusted to suppress the color misregistration of each color toner image. An object of the present invention is to provide an image forming apparatus.

An image forming apparatus according to the present invention includes a carrier that can carry and move a toner image formed by using a scanning line, and a first toner image that rotates a first toner image having an edge that is inclined with respect to the scanning line. formed on an image bearing member, a first image forming unit to be transferred to the conveying member, forming a second image bearing member for rotating the second toner image having an edge slope equal to the first toner image, a second image forming unit to be transferred to the conveying member at a predetermined detection position in the width direction orthogonal to the moving direction of the conveying member, and capable of detecting sensing means and said second toner image and the first toner image , the said detection means based on the time difference to detect the second toner image and the first toner image is formed on the first toner image and the second image bearing member formed on said first image bearing member and adjusting means for adjusting the main scanning direction of the relative position of the two-toner image, the first preparative A first graduation forming means for forming a first scale in association with the scanning lines forming the over image to a predetermined first position of both ends in the width direction of the conveying member, to the scanning lines to form the second toner image A second scale forming means for forming a second scale at a predetermined second position at both ends in the width direction orthogonal to the rotation direction of the second image carrier, and a first scale detection for detecting the first scale. Means, a second scale detecting means for detecting the second scale, and at the time of non-image formation, according to the positional relationship between the detection position, the first position, and the second position, The amount of deviation in the moving direction of the transport body with respect to the second scale is proportionally distributed at the detection position, and the amount of shift in the movement direction of the transport body at the proportionally distributed detection position is reduced . wherein in the moving direction second image bearing Characterized in that a position or control means for controlling the peripheral speed of said second image bearing member.

  In the image forming apparatus according to the present invention, the second toner image is transferred when the second toner image is transferred so that the second toner image is transferred to a position shifted by a predetermined number of scanning lines from the first toner image on the conveyance body. Control body position or peripheral speed. For this reason, the second toner image is transferred to the conveyance body in a state in which the variation in the number of scanning lines in the sub-scanning direction due to the speed variation of the conveyance body is removed. For this reason, the interval between the first toner image and the second toner image that is transferred to the conveyance body and detected by the detection means does not exceed variations due to speed fluctuations at a distance corresponding to a predetermined number of scanning lines.

  Therefore, compared with the case where the number of scanning lines corresponding to the deviation between the first toner image and the second toner image on the transport body changes indefinitely in accordance with the speed change of the transport body, it accompanies the speed change of the transport body. The variation in the distance between the first toner image and the second toner image on the carrier can be small. For this reason, even if a large speed fluctuation occurs in the conveyance body, the position of the toner images formed on the plurality of image carriers in the main scanning direction can be precisely adjusted to suppress the color misregistration of each color toner image.

1 is an explanatory diagram of a configuration of an image forming apparatus. It is explanatory drawing of the pattern image transcribe | transferred on an intermediate transfer belt. FIG. 6 is an explanatory diagram of writing scales on a photosensitive drum and an intermediate transfer belt. It is explanatory drawing of an electric potential sensor. It is explanatory drawing of the output of an electric potential sensor. It is explanatory drawing of the structure of the peripheral speed control of the magenta photosensitive drum. It is a block diagram of the peripheral speed control of the magenta photosensitive drum. It is explanatory drawing of the position shift detection of the main scanning direction in the position of an optical sensor. It is explanatory drawing of arrangement | positioning of the pattern image at the time of the color shift correction | amendment of 4 colors of main scanning directions. It is explanatory drawing of arrangement | positioning of the pattern image of a comparative example. It is explanatory drawing of the adjustment mode of Example 2. FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. As long as the first toner image and the second toner image transferred to the conveyance body are shifted by a predetermined number of scanning lines, a part or all of the configuration of the embodiment is replaced with the present invention. Another embodiment in which the configuration is replaced can also be implemented.

  Therefore, the control of the second image carrier is not limited to the control of the peripheral speed and the rotational speed, but may be the control of the position of the second image carrier in the rotation direction of the transport body. However, the control of the exposure start position in the sub-scanning direction is not included. The conveyance body is not limited to the intermediate transfer belt that is in contact with the image carrier, and includes a recording material conveyance belt on which the recording material is sucked and conveyed to transfer the toner image from the image carrier. The image forming apparatus can be implemented regardless of the full color / monochrome, one drum type / tandem type, recording material conveyance method / intermediate transfer method, type of image carrier, charging method, exposure method, transfer method, and fixing method. In the present embodiment, only main parts related to toner image formation / transfer will be described. However, the present invention includes a printer, various printing machines, a copier, a fax machine, a composite machine, in addition to necessary equipment, equipment, and a housing structure. It can be implemented in various applications such as a machine.

<Image forming apparatus>
FIG. 1 is an explanatory diagram of the configuration of the image forming apparatus. As shown in FIG. 1, the image forming apparatus 100 is a tandem intermediate transfer type full-color printer in which image forming units PY, PM, PC, and PK are arranged along an intermediate transfer belt 9.

  In the image forming unit PY, a yellow toner image is formed on the photosensitive drum 1Y (first image carrier) and transferred to the intermediate transfer belt 9. In the image forming unit PM, a magenta toner image is formed on the photosensitive drum 1M (second image carrier) and transferred to the intermediate transfer belt 9. In the image forming units PC and PK, a cyan toner image and a black toner image are formed on the photosensitive drums 1C and 1K, respectively, and transferred to the intermediate transfer belt 9.

  The four color toner images transferred to the intermediate transfer belt 9 are conveyed to the secondary transfer portion T2 and secondarily transferred to the recording material P. The separation roller 15 separates the recording material P drawn from the recording material cassette 20 one by one and sends it to the registration roller 16. The registration roller 16 sends the recording material P to the secondary transfer portion T2 in time with the toner image on the intermediate transfer belt 9. The recording material P on which the four-color toner images are secondarily transferred at the secondary transfer portion T2 is separated from the intermediate transfer belt 9 by the curvature and conveyed to the fixing device 17. The recording material P is heated and pressurized by the fixing device 17 to fix the toner image on the surface, and then discharged to the outside of the machine body.

  The image forming units PY, PM, PC, and PK are configured substantially the same except that the color of toner used in the developing devices 4Y, 4M, 4C, and 4K is different from yellow, magenta, cyan, and black. Hereinafter, the image forming unit PY will be described, and redundant description of the other image forming units PM, PC, and PK will be omitted.

  The image forming unit PY surrounds the photosensitive drum 1Y and includes a corona charger 2Y, an exposure device 3Y, a developing device 4Y, a transfer roller 5Y, and a drum cleaning device 6Y. The photosensitive drum 1Y has a photosensitive layer formed on the outer peripheral surface of an aluminum cylinder, and rotates in the direction of arrow A at a predetermined process speed. The corona charger 2Y irradiates the photosensitive drum 1Y with charged particles associated with corona charging to charge the photosensitive drum 1Y to a uniform negative polarity dark portion potential VD. The exposure apparatus 3Y scans the scanning line image data obtained by developing the yellow separated color image with a rotating mirror, and writes an electrostatic image of the image on the surface of the charged photosensitive drum 1Y. The developing device 4Y supplies toner to the photosensitive drum 1Y to develop the electrostatic image into a toner image.

  The transfer roller 5Y presses the inner surface of the intermediate transfer belt 9 to form a primary transfer portion TY between the photosensitive drum 1Y and the intermediate transfer belt 9. By applying a DC voltage to the transfer roller 5Y, the toner image carried on the photosensitive drum 1Y is primarily transferred to the intermediate transfer belt 9. The drum cleaning device 6Y collects the transfer residual toner attached to the surface of the photosensitive drum 1Y that has passed through the primary transfer portion TY by sliding the cleaning blade against the photosensitive drum 1Y.

  The intermediate transfer belt 9 is supported around a tension roller 12, a counter roller 10, and a driving roller 13, and is driven by the driving roller 13 to rotate in the arrow B direction. The secondary transfer portion T2 is configured by bringing the secondary transfer roller 11 into contact with the intermediate transfer belt 9 supported by the counter roller 10. By applying a DC voltage to the secondary transfer roller 11, the toner image carried on the intermediate transfer belt 9 is secondarily transferred to the recording material P conveyed through the secondary transfer portion T2. The belt cleaning device 18 rubs the intermediate transfer belt 9 with a cleaning blade to collect the transfer residual toner attached to the intermediate transfer belt 9.

<Optical sensor>
FIG. 2 is an explanatory diagram of a pattern image transferred onto the intermediate transfer belt. As shown in FIG. 1, the optical sensor 31 is a reflective light quantity sensor that detects regular reflected light of infrared light emitted from a light emitting element with a light receiving element and outputs an analog voltage corresponding to the amount of incident light. While the surface of the intermediate transfer belt 9 is specularly reflecting the infrared light efficiently, the toner particles scatter the reflected light. Therefore, when the toner image is transferred to the intermediate transfer belt 9, the light receiving element The amount of light detected by decreases. The optical sensor 31 detects the four color toner images transferred onto the intermediate transfer belt 9 and detects the color misregistration state of the four colors of the image forming apparatus 100.

  As shown in FIG. 2A, the intermediate transfer belt 9 is moved at a substantially constant speed in the direction of arrow B by a drive motor (not shown), and moves from right to left. The image forming unit PY forms a color misregistration adjustment pattern image 35 and transfers it to the intermediate transfer belt 9. The image forming unit PM forms a color misregistration adjustment pattern image 36 and transfers it to the interval between the pattern images 35 on the intermediate transfer belt 9. As shown in FIG. 2A, when the intermediate transfer belt 9 moves in the direction of arrow B, the reflected state of infrared light differs between the portions where the pattern images 35 and 36 are present and the portions where the pattern images 35 and 36 are absent. Thus, an output corresponding to the presence or absence of the pattern images 35 and 36 is obtained.

  FIG. 2B shows a signal obtained by digitizing the output from the optical sensor 31. A portion where the pattern images 35 and 36 are present is a pulse signal at a low level, and a portion where the pattern images 35 and 36 are absent is a high level pulse signal. The color misregistration state in the main scanning direction can be calculated from the time interval of the pulse signal.

<Electrostatic image scale and potential sensor>
FIG. 3 is an explanatory diagram of writing scales on the photosensitive drum and the intermediate transfer belt. FIG. 4 is an explanatory diagram of the potential sensor. FIG. 5 is an explanatory diagram of the output of the potential sensor. In FIG. 3, only the image position indices in the yellow and magenta image forming portions PY and PM are described. The cyan and black image forming units PC and PK are the same as the magenta image forming unit PM, and thus redundant description is omitted.

  As shown in FIG. 3, the exposure device 3Y records the electrostatic image index 21Y on the photosensitive drum 1Y in synchronization with normal image formation. The potential sensors 22Y and 22M detect the electrostatic image graduations 21Y and 21M formed on the photosensitive drums 1Y and 1M. As shown in FIG. 5A, the electrostatic image graduation 21Y is a striped pattern in which lines and spaces are repeated every 4 pixels in 600 dpi units.

  The potential sensor 22Y includes an antenna portion made of a conductor. The photosensitive drum 1Y on which the electrostatic image index 21Y is recorded rotates in the arrow A direction. An induced current is generated in the antenna portion of the potential sensor 22Y in response to a change in the electric field accompanying the movement of the electrostatic image graduation 21Y. By detecting the induced current, the position of the electrostatic image graduation that is the image position index can be detected. When the electrostatic image index 21Y moves to the position of the charging unit 2Y as the photosensitive drum 1Y rotates, it is erased by a charging operation by the charging unit 2Y.

  As shown in FIG. 4A, the potential sensors 22Y and 22M are formed in an L shape after applying an adhesive on a base film 332 made of a polyimide film having a width of 4 mm, a length of 15 mm, and a thickness of 25 μm. A conducting wire 331 is disposed. A protective film 333 made of a polyimide film having the same size and thickness as the base film 332 is adhered so as to cover the L-shaped conductive wire 331. The potential sensors 22Y and 22M are positioned so that the scale lines of the detection unit 334 and the electrostatic image graduations 21Y and 21M are parallel, and the roots are fixed to the housing side of the image forming apparatus.

  As shown in FIG. 4B, the potential sensors 22Y and 22M are curved at the tip side so that the base film 332 side contacts the photosensitive drums 1Y and 1M. The potential sensors 22Y and 22M are in close contact with the photosensitive drums 1Y and 1M by the bending spring force.

  As shown in FIG. 5 (b) with reference to FIG. 3, the potential distribution of the electrostatic image graduations 21Y and 21M in the rotation direction of the photosensitive drums 1Y and 1M is reduced to a rectangular wave as the potential decreases in the peripheral portion. Don't be. When the potential sensors 22Y and 22M relatively move along the electrostatic image graduations 21Y and 21M having such a potential distribution, a signal output as shown in FIG. 5C is obtained. When the nearby potential changes with relative movement, an induced current is generated in the potential sensors 22Y and 22M, and a waveform obtained by differentiating the potential distribution of FIG. 5B from the output unit 335 of the potential sensors 22Y and 22M. Is output.

  The distance from the detection position of the potential sensor 22Y to the primary transfer portion TY is set equal to the distance from the write position of the magnetic writing head 25 to the primary transfer portion TY. The magnetic writing head 25 records the magnetic scale 24 on the magnetic recording layer of the intermediate transfer belt 9 in synchronization with the detection of the electrostatic image scale 21 </ b> Y by the potential sensor 22. The electrostatic image index 21Y recorded on the photosensitive drum 1Y is transferred as a magnetic index 24 on the intermediate transfer belt 9.

<Position shift correction control in sub-scanning direction>
FIG. 6 is an explanatory diagram of the configuration of the peripheral speed control of the magenta photosensitive drum. FIG. 7 is a block diagram of the peripheral speed control of the magenta photosensitive drum. Here, alignment in the sub-scanning direction at the time of image formation in the magenta image forming unit PM will be described, and redundant description regarding the cyan and black image forming units PC and PK will be omitted.

  As shown in FIG. 1, the photosensitive drum 1Y is rotationally driven at a substantially constant rotational speed in the direction of arrow A by the drive motor 32M. The intermediate transfer belt 9 is rotationally driven in the direction of arrow B by a drive motor (not shown). In the image forming apparatus 100, if the formation timing of the toner image in the sub-scanning direction in the image forming units PY and PM is shifted during image formation, a color shift in the rotational direction of the intermediate transfer belt 9 occurs in the details of the full-color image. Further, when the speed fluctuation occurs in the intermediate transfer belt 9 and the transfer position of the toner image on the intermediate transfer belt 9 is shifted in the sub-scanning direction at the primary transfer portion TY and the primary transfer portion TM of the photosensitive drum 1Y. Further, a color shift in the rotation direction of the intermediate transfer belt 9 occurs in the details of the output image.

As shown in FIG. 3, the magnetic writing head 25, which is an example of a first scale forming unit, has a magnetic scale 24, which is an example of a first scale, associated with a scanning line that forms a pattern image 35. Form. The exposure apparatus 3M that is an example of the second scale forming unit forms an electrostatic image scale 21M that is an example of the second scale on the photosensitive drum 1M in association with the scanning line that forms the pattern image 36. When transferring the magenta toner image to the intermediate transfer belt 9, the image carrier rotation control unit 43 transfers the photosensitive drum 1M to the magnetic scale 24 on the carrier so that the magenta toner image is transferred to the same position as the yellow image toner image. The electrostatic image graduation 21M is positioned.

The exposure device 3Y forms an electrostatic image index 21Y, which is an example of an electrostatic image for each predetermined number of scanning lines, on the photosensitive drum 1Y using the end of the scanning line of the pattern image 35 in the main scanning direction. The magnetic writing head 25 records the magnetic scale 24 on the magnetic track of the intermediate transfer belt 9 every time the electrostatic image scale 21Y is read by the antenna-type potential sensor 22Y in the vicinity of the transfer portion of the pattern image 35. The exposure apparatus 3M forms an electrostatic image index 21M, which is an example of an electrostatic image for each predetermined number of scanning lines, on the photosensitive drum 1M using the end of the scanning line of the pattern image 36 in the main scanning direction.

  In the image forming apparatus 100, a scale corresponding to the scanning line of the toner image is formed on each of the photosensitive drum 1M and the intermediate transfer belt 9. A scale between the photosensitive drum 1M and the intermediate transfer belt 9 is detected in the vicinity of the magenta primary transfer portion TM, and a speed difference between the photosensitive drum 1M and the intermediate transfer belt 9 is detected. Based on the detected speed difference, the photosensitive drum 1M is detected. The rotation speed of is constantly changing. Thus, the deviation in the sub-scanning direction between the toner image on the photosensitive drum 1M and the toner image on the intermediate transfer belt 9 is corrected, and the color deviation between yellow and magenta in the output image is reduced.

  As the intermediate transfer belt 9 moves in the direction of arrow B, the magnetic scale 24 reaches the magenta image forming portion PM. The magnetic reading head 26 </ b> M detects the magnetic scale 24 recorded on the intermediate transfer belt 9. On the other hand, in the image forming unit PM, the electrostatic image index 21M is recorded and detected by the potential sensor 22M in the same manner as the yellow image forming unit PY. In the image forming unit PM, rotation control of the photosensitive drum 1M is performed so that the electrostatic image graduation 21M detected by the potential sensor 22M and the magnetic graduation 24 detected by the magnetic reading head 26M are aligned with each other in the primary transfer unit TM. Is called.

  As shown in FIG. 6, the image forming unit PM (PC, PK) includes an electrostatic image graduation 21, a potential sensor 22, a magnetic graduation 24, and a magnetic reading head 26 at both ends in the main scanning direction. A first electrostatic image index 21MT and a second electrostatic image index 21ME are recorded on both ends of the photosensitive drum 1M using the end portions of the scanning lines by exposure of the exposure apparatus 3M shown in FIG. The potential sensors 22MT and 22ME detect the first electrostatic image index 21MT and the second electrostatic image index 21ME, respectively.

  A magnetic recording layer is disposed at both ends of the intermediate transfer belt 9, and a first magnetic scale 24T and a second magnetic scale 24E are respectively transferred to a pair of electrostatic image graduations 21Y at both ends of the photosensitive drum 1Y shown in FIG. It is recorded. The magnetic read heads 26MT and 26ME detect the first magnetic scale 24T and the second magnetic scale 24E, respectively.

  As shown in FIG. 7, the first potential sensor 22MT detects the first electrostatic image scale 21MT and inputs the first electrostatic image scale detection signal 27T to the image position correction amount calculation unit 41. The first electrostatic image scale detection signal 27T is a pulse signal corresponding to the first electrostatic image scale 21MT. The second potential sensor 22ME detects the second electrostatic image scale 21ME, and inputs the second electrostatic image scale detection signal 27E to the image position correction amount calculation unit 41. The second electrostatic image scale detection signal 27E is a pulse signal corresponding to the second electrostatic image scale 21ME.

  The first magnetic read head 26MT detects the first magnetic scale 24T and inputs the first magnetic scale detection signal 28T to the image position correction amount calculation unit 41. The first magnetic scale detection signal 28T is a pulse signal corresponding to the first magnetic scale 24T. The second magnetic read head 26ME detects the second magnetic scale 24E and inputs the second magnetic scale detection signal 28E to the image position correction amount calculation unit 41. The second magnetic scale detection signal 28E is a pulse signal corresponding to the second magnetic scale 24E.

  The image position correction amount calculation unit 41 calculates the image carrier image position and the carrier image position at the detection position (broken line in the figure) of the optical sensor 31 in the width direction of the intermediate transfer belt 9 from the four input signals. The image position correction amount 42 is calculated so as to match. The image position correction amount 42 calculated by the image position correction amount calculation unit 41 is input to the image carrier rotation control unit 43. The image carrier rotation control unit 43 determines the rotation speed of the photosensitive drum 1M based on the input image position correction amount 42, and inputs the motor drive signal 44 to the drive motor 32M to rotate the photosensitive drum 1M.

  The image forming apparatus 100 eliminates color misregistration in the sub-scanning direction of each color image while maintaining print productivity by controlling the rotational speeds of the photosensitive drums 1M, 1C, and 1K in real time. However, the control of the rotational speed of the photosensitive drums 1M, 1C, and 1K cannot eliminate the color misregistration of each color in the main scanning direction. The color misregistration of each color image in the main scanning direction cannot be resolved unless the image formation start timing on the scanning line is adjusted in the photosensitive drums 1M, 1C, and 1K.

<Position misalignment correction control in main scanning direction>
Here, the alignment in the main scanning direction in the magenta image forming unit PM will be described, and a redundant description of the cyan and black image forming units PC and PK will be omitted. Only the alignment of the magenta toner image with respect to the yellow toner image will be described, and redundant description regarding the alignment of the cyan toner image and the black toner image with respect to the yellow toner image will be omitted. For the four colors including cyan and black, it is possible to detect the color misregistration state by the method described below.

  As shown in FIG. 1, when the toner image forming position in the image forming unit PY and the toner image forming position in the image forming unit PM are shifted in the main scanning direction, the image forming apparatus 100 changes the output image to yellow and magenta. Color shift in the main scanning direction occurs. Therefore, the image forming apparatus 100 executes the adjustment mode during non-image formation, detects the color misregistration state in the main scanning direction of the yellow toner image and the magenta toner image, and automatically corrects the color misregistration. Yes.

  As shown in FIG. 2A, the intermediate transfer belt 9 moves in the arrow B direction. In the adjustment mode, the photosensitive drums 1 </ b> Y and 1 </ b> M form pattern images 35 and 36 for color misregistration adjustment and transfer them to the intermediate transfer belt 9. The pattern images 35 and 36 are registration correction toner images on the photosensitive drums 1Y and 1M. A yellow pattern image 35 for registration correction and a magenta pattern image 36 are alternately transferred onto the intermediate transfer belt 9. The pattern images 35 and 36 are linear patterns inclined by 45 degrees with respect to the conveyance direction of the intermediate transfer belt 9.

  In the adjustment mode, the pattern images 35 and 36 transferred onto the intermediate transfer belt 9 are detected by the optical sensor 31. The pattern images 35 and 36 are read by the reflective optical sensor 31 to adjust the start timing of image formation in the main scanning direction in the image forming unit PM, and the color shift between yellow and magenta in the width direction of the intermediate transfer belt 9 Reduce.

As shown in FIG. 2B, the time interval from the pulse signal detecting the yellow pattern image 35 to the pulse signal detecting the magenta pattern image 36 is T1. The time interval from the pulse signal that detected the magenta pattern image 36 to the pulse signal that detected the yellow pattern image 35 is T2. Let the moving speed of the intermediate transfer belt 9 be v. At this time, the color shift amount ΔL in the main scanning direction between the yellow image and the magenta image at the time of image formation can be calculated using the following equation.
ΔL = ((T2−T1) / 2) × v (1)

  FIG. 2A shows a state where there is no color shift in the main scanning direction. At this time, as shown in FIG. 2B, the pulse signal obtained by digitizing the output of the optical sensor 31 has a constant period. In FIG. 2B, since T1 = T2, the color misregistration amount ΔL = 0 according to the equation (1).

FIG. 2C shows a state in which the magenta image is shifted in the main scanning direction by L1 with respect to the yellow image. At this time, as shown in FIG. 2D, the pulse signal obtained by digitizing the output of the optical sensor 31 does not have a constant period. In FIG. 2D, since T1 ′ <T2 ′, the color misregistration amount L1> 0 is obtained according to the equation (1).
L1 = ((T2′−T1 ′) / 2) × v

  The color shift amount L1 in the main scanning direction calculated in this way is eliminated by adjusting the start timing of image exposure on the scanning line in the exposure apparatus 3M shown in FIG.

<Influence of speed fluctuation of intermediate transfer belt>
As shown in FIG. 2A, when speed fluctuation occurs in the intermediate transfer belt 9 in the adjustment mode, the primary transfer portion TY of the photosensitive drum 1Y and the primary transfer portion TM of the photosensitive drum 1M are moved onto the intermediate transfer belt 9. The transfer positions of the pattern images 35 and 36 are shifted in the sub-scanning direction. For example, when the transfer position of the pattern image 36 is shifted to the pattern image 36 ′ in the sub-scanning direction, T1 shown in FIG. 2B becomes smaller than T2. As a result, although the amount of deviation in the main scanning direction between the yellow image and the magenta image is 0, the amount of deviation ΔL> 0 calculated by the equation (1) occurs, and the exposure apparatus 3M automatically scans. The start timing of image exposure on the line is adjusted. As a result, a color shift in the width direction of the intermediate transfer belt 9 occurs in the details of the output image.

  That is, even when the pattern images 35 and 36 for color misregistration adjustment are formed, there are factors that cause the color misregistration state to fluctuate such as the speed variation of the intermediate transfer belt 9, and this causes an error in color misregistration adjustment in the main scanning direction. For this reason, conventionally, pattern images 35 and 36 are repeatedly formed over the entire circumference of the intermediate transfer belt 9, and an error is reduced by averaging the results of reading a large number of T1 and T2 with the optical sensor 31. .

  However, when the pattern images 35 and 36 are formed over the entire circumference of the intermediate transfer belt 9, the time for interrupting the image formation becomes longer. If color misregistration adjustment in the main scanning direction is performed following magenta and cyan, black, the intermediate transfer belt 9 is interrupted for three turns, and the operation rate of the image forming apparatus is reduced. The amount of toner used other than the original image formation increases, resulting in wasted use of toner and power consumption. The secondary transfer roller 11 becomes dirty. Waste toner increases.

  Therefore, in the following embodiments, the positional deviation correction control in the sub-scanning direction, which is executed at the time of image formation, is also executed in the adjustment mode, and the influence of the speed fluctuation of the intermediate transfer belt 9 on the color deviation adjustment in the main scanning direction is performed. It is decreasing. In addition, when the control for reducing the color misregistration by controlling the rotational speed of the photosensitive drum 1M is applied to the image position adjustment mode in the main scanning direction, the following problems exist.

<Example 1>
FIG. 8 is an explanatory diagram of detection of misalignment in the main scanning direction at the position of the optical sensor. FIG. 9 is an explanatory diagram of the arrangement of pattern images at the time of color misregistration correction in the main scanning direction of four colors. FIG. 10 is an explanatory diagram of the arrangement of pattern images of the comparative example.

  As shown in FIG. 1, the exposure control unit 7, which is an example of an execution unit, controls the image forming units PY, PM, PC, and PK at the time of non-image formation, and controls the image forming units PY, PM, PC, and PK. An adjustment mode for adjusting the relative position of the toner image in the main scanning direction is executed. In the adjustment mode, one image forming unit PY and a plurality of image forming units PM, PC, and PK arrange parallel linear toner images inclined only in one direction with respect to the scanning line on the intermediate transfer belt 9.

  As shown in FIG. 3, the intermediate transfer belt 9, which is an example of a transport body, can transport a toner image formed using scanning lines. The image forming unit PY which is an example of the first image forming unit forms a first toner image having an edge inclined obliquely with respect to the scanning line on the photosensitive drum 1Y which is an example on the first image carrier. Transfer to the transfer belt 9. The image forming unit PM, which is an example of the second image forming unit, forms a second toner image having an edge with the same inclination as the first toner image on the second image carrier, and transfers it to the intermediate transfer belt 9.

  As shown in FIG. 6, the optical sensor 31, which is an example of a detection unit, includes a pattern image 35, which is an example of a first toner image, at a predetermined position in the width direction and the rotation direction perpendicular to the rotation direction of the intermediate transfer belt 9. A pattern image 36 which is an example of a second toner image is detected. The exposure control unit 7, which is an example of an adjusting unit, is formed on the photosensitive drum 1 </ b> M and the toner image formed on the photosensitive drum 1 </ b> M based on the time difference at which the optical sensor 31 detects the pattern image 35 and the pattern image 36. The relative position of the toner image in the main scanning direction is adjusted.

  When transferring the pattern image 36 to the intermediate transfer belt 9, the image carrier rotation control unit 43, which is an example of a control unit, positions the electrostatic image index 21 </ b> M of the photosensitive drum 1 </ b> M on the magnetic index 24 on the conveyance body. The position of the photosensitive drum 1M in the rotation direction of the intermediate transfer belt 9 or the peripheral speed of the photosensitive drum 1M so that the pattern image 36 is transferred onto the intermediate transfer belt 9 at a position shifted from the pattern image 35 by a predetermined number of scanning lines. To control.

  The magnetic writing head 25 is disposed at both ends of the intermediate transfer belt 9 so as to correspond to both ends of the scanning line for forming a toner image on the photosensitive drum 1Y. The potential sensors 22ME and MT are arranged at both ends of the photosensitive drum 1M so as to correspond to both ends of the scanning line for forming a toner image on the photosensitive drum 1M. The exposure control unit 7 cancels out the shift amount obtained by proportionally distributing the shift amounts of the magnetic graduations 24E and 24T and the electrostatic image graduations 21ME and 21MT at both ends in the width direction of the intermediate transfer belt 9 to the position of the optical sensor 31. Thus, the photosensitive drum 1M is controlled.

  The reflective optical sensor 31 detects registration correction pattern images 35 and 36 formed on the intermediate transfer belt 9. In FIG. 6, the detection position of the optical sensor 31 in the width direction of the intermediate transfer belt 9 is schematically shown by a broken line.

  The image forming unit PM (PY, PC, PK) includes an electrostatic image graduation 21, a potential sensor 22, a magnetic graduation 24, a magnetic writing head 25, and a magnetic reading head 26 at both ends in the main scanning direction. A first electrostatic image index 21MT and a second electrostatic image index 21ME are recorded on both ends of the photosensitive drum 1M using the end portions of the scanning lines by exposure of the exposure apparatus 3M shown in FIG. The potential sensors 22MT and 22ME detect the first electrostatic image index 21MT and the second electrostatic image index 21ME, respectively.

  Magnetic recording layers are arranged at both ends of the intermediate transfer belt 9, and a first magnetic scale 24T and a second magnetic scale 24E are recorded by transferring the electrostatic image scales 21YT and 21YE of the photosensitive drum 1Y shown in FIG. Yes. The magnetic read heads 26MT and 26ME detect the first magnetic scale 24T and the second magnetic scale 24E, respectively.

  As shown in FIG. 7, the first potential sensor 22MT detects the first electrostatic image scale 21MT and inputs the first electrostatic image scale detection signal 27T to the image position correction amount calculation unit 41. The first electrostatic image scale detection signal 27T is a pulse signal corresponding to the first electrostatic image scale 21MT. The second potential sensor 22ME detects the second electrostatic image scale 21ME, and inputs the second electrostatic image scale detection signal 27E to the image position correction amount calculation unit 41. The second electrostatic image scale detection signal 27E is a pulse signal corresponding to the second electrostatic image scale 21ME.

  The first magnetic read head 26MT detects the first magnetic scale 24T and inputs the first magnetic scale detection signal 28T to the image position correction amount calculation unit 41. The first magnetic scale detection signal 28T is a pulse signal corresponding to the first magnetic scale 24T. The second magnetic read head 26ME detects the second magnetic scale 24E and inputs the second magnetic scale detection signal 28E to the image position correction amount calculation unit 41. The second magnetic scale detection signal 28E is a pulse signal corresponding to the second magnetic scale 24E.

  The image position correction amount calculation unit 41 calculates the image carrier image position and the carrier image position at the detection position (broken line in the figure) of the optical sensor 31 in the width direction of the intermediate transfer belt 9 from the four input signals. The image position correction amount 42 is calculated so as to match. The image position correction amount 42 calculated by the image position correction amount calculation unit 41 is input to the image carrier rotation control unit 43. The image carrier rotation control unit 43 determines the rotation speed of the photosensitive drum 1M based on the input image position correction amount 42, and inputs the motor drive signal 44 to the drive motor 32M to rotate the photosensitive drum 1M.

  By the way, as shown in FIG. 1, when there is an inclination in the scanning lines formed on the photosensitive drums 1M, 1C, and 1K by the exposure devices 3M, 3C, and 3K, all areas in the main scanning direction are completely formed during image formation. Color misregistration cannot be resolved. A scanning line inclined in the conveying direction of the intermediate transfer belt 9 on the photosensitive drum 1M is overlapped with a deviation amount = 0 on one end side in the width direction of the intermediate transfer belt 9 with respect to a scanning line not inclined on the intermediate transfer belt 9. When combined, a large overlay error occurs on the other end side in the width direction of the intermediate transfer belt 9.

  For this reason, in normal image formation, the image forming apparatus 100 controls the peripheral speed of the photosensitive drum 1M so that the image carrier image position and the carrier image position coincide with each other at the center position in the main scanning direction. Induces an apparent color shift at a minimum. At the time of image formation, the peripheral speed of the photosensitive drum 1M is controlled in real time so that the shift amount at the center position in the main scanning direction of the scanning line of the photosensitive drum 1M is corrected to zero. As a result, although the influence of the inclination of the scanning line slightly appears at both ends in the width direction of the intermediate transfer belt 9, the apparent color misregistration amount becomes considerably small as a whole.

  However, when the adjustment mode is executed in this state and the pattern images 35 and 36 for color misregistration adjustment are formed and read, an error occurs in the detection timing of the pattern images 35 and 36 by the optical sensor 31. In the image forming apparatus 100, the optical sensor 31 is installed at a position deviated from the center in the main scanning direction. For this reason, as shown in FIG. 2A, at the position of the optical sensor 31, a certain positional shift caused by the inclination of the scanning line on the photosensitive drum 1M occurs in the pattern image 36, and the adjustment mode is set. Even if it repeats, it will be the situation where a color shift is not eliminated. The color shift caused by the inclination of the scanning line on the photosensitive drum 1M increases as the installation position of the optical sensor 31 moves away from the center in the main scanning direction, and becomes most noticeable at the end in the main scanning direction. As a result, even if the color misregistration adjustment in the sub-scanning direction is performed, it is necessary to cope with the averaging process by forming a large number of pattern images 35 and 36 as in the prior art.

  Therefore, in the adjustment mode of the first embodiment, the position in the main scanning direction where the scanning lines on the photosensitive drum 1M and the scanning lines having different inclinations on the intermediate transfer belt 9 are overlapped is different from the position at the time of normal image formation. The position at which the scanning lines with different inclinations separated by a predetermined number of scanning lines in the transport direction intersect on the intermediate transfer belt 1 is shifted from the central portion in the main scanning direction at the time of image formation to the position of the optical sensor 31. The apparent color misregistration in the entire image is intentionally enlarged to minimize the scanning line misalignment at the position of the optical sensor 31. By controlling the photosensitive drum 1M with a speed correction amount different from that at the time of image formation so that the amount of deviation between the yellow and magenta scanning lines becomes zero at the position of the optical sensor 31 in the main scanning direction, Eliminate color misregistration errors.

  As shown in FIG. 7, the image position correction amount calculation unit 41 includes a first electrostatic image scale detection signal 27T, a second electrostatic image scale detection signal 27E, a first magnetic scale detection signal 28T, and a second magnetic scale detection. A signal 28E is input. When the first electrostatic image scale rising detection unit 51 detects the rising edge of the first electrostatic image scale detection signal 27T, the detection time is stored in the first electrostatic image scale time storage FIFO 53. Similarly, the rising edge of the second electrostatic image scale detection signal 27E is detected by the second electrostatic image scale rising detection unit 52, and the detection time is stored in the second electrostatic image scale time storage FIFO.

When the target image height electrostatic image scale time calculation unit 55 stores data in both the first electrostatic image scale time storage FIFO 53 and the second electrostatic image scale time storage FIFO 54, the target image height electrostatic image scale time calculation unit 55 reads the data from each of them. The electrostatic image graduation time at is calculated. Here, the target image height is a detection position of the optical sensor 31 in the width direction of the intermediate transfer belt 9 indicated by a broken line in FIG. The electrostatic image graduation time calculation at the target image height, that is, the calculation of the image position correction amount 42 in the optical sensor 31 is performed as follows.

As shown in FIG. 8, the distance between the first electrostatic image scale detection position and the pattern image detection position is LD1, and the distance between the second electrostatic image scale detection position and the pattern image detection position is LD2. The time read from the first electrostatic image scale time storage FIFO 53 is TD1, and the time read from the second electrostatic image scale time storage FIFO 54 is TD2. At this time, the electrostatic image graduation time TD at the target image height is obtained by the following equation that proportionally distributes the shift amount of both ends to the position of the optical sensor 31.
TD = TD1 + (TD2-TD1) × (LD1 / (LD1 + LD2)) (2)

The result calculated in this way is stored in the target image height electrostatic image scale time storage FIFO 56. The same processing is applied to the magnetic scale time TB at the target image height and is calculated by the following equation.
TB = TB1 + (TB2-TB1) × (LB1 / (LB1 + LB2)) (3)

The magnetic scale time TB is stored in the target image height magnetic scale time storage FIFO 66. When data is stored in both the target image height scale time storage FIFO 56 and the target image height magnetic scale time storage FIFO 66, the image position difference calculation unit 57 reads data from each. The image position difference calculation unit 57 calculates a deviation amount ΔX between the image carrier image position and the carrier image position at the target image height from the read data by the following equation. In the following equation, v is the moving speed of the intermediate transfer belt 9.
ΔX = (TD−TB) × v (4)

  The image position difference calculation unit 57 inverts the sign by multiplying ΔX calculated by the equation (4) by −1, and outputs the result as an image position correction amount 42. As shown in FIG. 6, the calculated image position correction amount 42 is input to the image carrier rotation control unit 43. The image carrier rotation control unit 43 transfers the pattern image 36 on the photosensitive drum 1M to the predetermined transfer line distance from the pattern image 35 on the intermediate transfer belt 9 by the primary transfer unit TM shown in FIG. As described above, the rotational speed of the photosensitive drum 1M is controlled.

  The above-described control for transferring the pattern image 36 by positioning it at the distance of the predetermined number of scanning lines is performed only when the pattern image 36 for registration correction is transferred. As a result, it is possible to accurately detect the color misregistration state in the main scanning direction of the pattern image 36 on the photosensitive drum 1M while suppressing the influence of the speed fluctuation of the intermediate transfer belt 9.

  As shown in FIG. 9, the image forming unit PM has an interval between two pattern images 35 transferred by the image forming unit PY with a distance of scanning lines twice the predetermined number in the rotation direction of the intermediate transfer belt 9. A pattern image 36 having the same shape as the pattern image 35 is transferred to the center. The exposure control unit 7 determines that the image forming unit PM has a photosensitive drum according to the difference between the elapsed time from the pattern image 35 to the pattern image 36 by the optical sensor 31 and the elapsed time from the pattern image 36 to the pattern image 35 thereafter. The position of the image written in 1M in the main scanning direction is adjusted.

  In the adjustment mode of the first embodiment, detection can be performed with a simple pattern specialized for color shift detection in the main scanning direction. For this reason, the down time required for the adjustment mode is shortened. The toner consumption is also reduced.

  On the other hand, as shown in FIG. 10, the conventional pattern images 81, 82, 83, 84 are toner images of the first color, the second color, the third color, and the fourth color on the intermediate transfer belt 9, respectively. It is. In this case, the downtime is longer than that in the first embodiment, and the toner consumption is increased.

  In the adjustment mode of the first embodiment, image position indexes are recorded along the sub-scanning direction on each of the photosensitive drum and the intermediate transfer belt, and the rotational speed of the photosensitive drum is set so that the corresponding image position indexes coincide with each other at the transfer position. To control.

  When the registration correction pattern image is formed, the rotational speed of the photosensitive drum is controlled so that the image position indexes coincide with each other at the image height at which the registration correction pattern image is detected in the main scanning direction.

  According to the adjustment mode of the first embodiment, it is possible to suppress the influence of the speed fluctuation in the sub-scanning direction of the carrier when detecting the color misregistration in the main scanning direction. This eliminates the need for processing such as averaging fluctuations in the sub-scanning direction, and enables high-quality image formation while suppressing a decrease in productivity of the image forming apparatus.

  According to the adjustment mode of the first embodiment, each color toner image at the time of image formation is directly used for each color by using a magnetic recording layer, a magnetic writing head, a magnetic reading head, a potential sensor, and the like for alignment in the sub-scanning direction. The alignment accuracy of the toner image in the main scanning direction can be increased. The peripheral speed control of the photosensitive drums 1M, 1C, and 1K in the adjustment mode changes one parameter used for the calculation of the image position correction amount calculation unit in the peripheral speed control program for the photosensitive drums 1M, 1C, and 1K at the time of image formation. Can only be realized. Therefore, it is possible to increase the alignment accuracy of each color toner image in the main scanning direction at a very low cost. New additional parts are not required, and the size of the image forming apparatus is not increased.

  According to the adjustment mode of the first embodiment, it is possible to provide a highly productive image forming apparatus by shortening the time required for forming and detecting a registration correction pattern image and reducing consumed toner.

  Note that the number of optical sensors that detect a pattern image for registration correction is not limited to one. When a plurality of optical sensors are used, the process of switching the position in the main scanning direction for aligning the scanning lines described in the first embodiment may be sequentially performed for each optical sensor.

<Example 2>
FIG. 11 is an explanatory diagram of the adjustment mode of the second embodiment. FIG. 11 shows only the image position indexes in the yellow and magenta image forming portions TY and TM. Since cyan and black are the same as magenta, description thereof is omitted.

  In Example 1, magnetic signals corresponding to the scanning lines of the photosensitive drum 1Y were recorded on the magnetic recording layer of the intermediate transfer belt 9. On the other hand, in the second embodiment, an optical scale fixed in advance on the intermediate transfer belt 9 is made to correspond to the scanning line of the photosensitive drum 1Y. In the second embodiment, the scale formed on the intermediate transfer belt 9 is used as a carrier image position index in the magenta primary transfer portion TM.

  In the second embodiment, the configuration and processing other than the carrier image position index, such as recording and detection of electrostatic image graduations formed on the photosensitive drums 1Y, 1M, 1C, and 1K, are the same as those in the first embodiment, and thus overlap. The description is omitted, and only the carrier image position index will be described below.

As shown in FIG. 11, a first graduation associated address comparator 76 which is an example of a means, the photosensitive drum with respect to the optical scale 71 is fixed to the intermediate transfer belt 9 is an example of a first memory provided in advance The scanning lines forming the pattern image 35 on 1Y are associated.

The exposure apparatus 3M that is an example of the second scale forming unit forms an electrostatic image scale 21M that is an example of the second scale on the photosensitive drum 1M in association with the scanning line that forms the pattern image 36.

  When transferring the pattern image 36 to the intermediate transfer belt 9, the image carrier rotation control unit 43, which is an example of a control unit, positions the electrostatic image index 21 </ b> M of the photosensitive drum 1 </ b> M on the magnetic index 24 on the conveyance body. The position of the photosensitive drum 1M in the rotation direction of the intermediate transfer belt 9 or the peripheral speed of the photosensitive drum 1M so that the pattern image 36 is transferred onto the intermediate transfer belt 9 at a position shifted from the pattern image 35 by a predetermined number of scanning lines. To control.

  The scale 71 is fixedly formed in advance on the surface of the intermediate transfer belt 9 over almost the entire length of the intermediate transfer belt 9. The scale 71 is a striped pattern that is processed so that the light reflectance is different for each pitch of 300 dpi (84.7 μm), corresponding to twice the scanning line pitch 600 dpi of the toner image formed on the photosensitive drums 1Y and 1M. Pattern. The scale 71 forms a reference portion serving as the origin of counting by partially missing a striped pattern in a part of the entire length of the intermediate transfer belt 9.

  The optical sensor 72Y is a reflection type in which regular reflection light of detection light emitted from the light emitting element is detected by the light receiving element. The optical sensor 72Y detects the repeated change in the amount of reflected light from the scale 71, and inputs a digitized pulse-like scale detection signal to the scale address count unit 73Y.

  The scale address counting unit 73Y increments the counter for each rising edge of the scale detection signal and counts the scale address detected by the optical sensor 72Y. Since the counter of the scale address count unit 73Y is reset when the above-described reference unit is detected, the scale address is a pulse count value from the reference unit.

  When detecting the rising edge of the electrostatic image scale detection signal input from the potential sensor 22Y, the rising detection unit 74 outputs an address storage request to the scale address count unit 73Y. When the address storage request is input from the rise detection unit 74, the scale address count unit 73Y for the yellow toner image stores the scale address count value in the image position address storage FIFO 75.

  Similar to the scale address count unit 73Y, the scale address count unit 73M of the magenta toner image counts the scale address detected by the optical sensor 72Y as a pulse count value from the reference unit. When data is stored in the image position address storage FIFO 75, the address comparison unit 76 reads one data and compares it with the address count value in the scale address count unit 73M. The address comparison unit 76 outputs a pulse signal that is an image position detection signal when the address count value in the scale address count unit 73M increases and becomes equal to the data read from the image position address storage FIFO 75.

  The image position correction amount calculation unit 41 uses the image position scale 71 as the carrier image position index by associating the electrostatic image graduation 21 </ b> Y with the address of the scale 71 output from the address comparison unit 76. In the second embodiment, the same function as that of the first embodiment is realized by replacing the image position detection signal output from the address comparison unit 76 with the magnetic scale detection signal in the first embodiment.

  In the second embodiment, the rising edges of the scale detection signal are counted as they are. However, by electrically dividing the rising edges of the scale detection signal and counting them, it is possible to control the image position with higher definition. .

1Y, 1M, 1C, 1K photosensitive drums 2Y, 2M, 2C, 2K charging rollers 3Y, 3M, 3C, 3K exposure devices 4Y, 4C, 4M, 4K developing devices 5Y, 5M, 5C, 5K primary transfer rollers 6Y, 6M, 6C, 6K drum cleaning device 9 intermediate transfer belt, 11 secondary transfer roller 21Y, 21M electrostatic image graduation, 22Y, 22M potential sensor 24 magnetic graduation, 25 magnetic writing head, 26M magnetic reading head 31 optical sensor, 32 drive Motor, 35, 36 Pattern image 41 Image position correction amount calculation unit, 43 Image carrier rotation control unit 71 Optical sensor, 72 Optical scale

Claims (6)

A carrier capable of carrying and moving a toner image formed using a scanning line;
Formed on the first image bearing member for rotating the first toner image having an edge which is inclined obliquely to the scanning lines, a first image forming unit to be transferred to the conveying member,
Formed on the second image bearing member for rotating the second toner image having an edge slope equal to the first toner image, a second image forming unit to be transferred to the conveying member,
At a predetermined detection position in the width direction orthogonal to the moving direction of the conveying member, and capable of detecting sensing means and said second toner image and the first toner image,
Based on the time difference the detection means detects the second toner image and the first toner image, second formed on the first toner image and the second image bearing member formed on said first image bearing member Adjusting means for adjusting the relative position of the toner image in the main scanning direction ;
A first graduation forming means for forming a first scale to a predetermined first position of both ends in the width direction of the conveying member in association with the scanning lines forming the first toner image,
A second scale forming means for forming a second graduation in the predetermined second position of the both ends in the width direction orthogonal to the direction of rotation of the second image bearing member in association with the scanning lines forming the second toner image,
First scale detecting means for detecting the first scale;
Second scale detection means for detecting the second scale;
During non-image formation, according to the positional relationship between the detection position, the first position, and the second position, the amount of shift in the moving direction of the transport body between the first scale and the second scale at both ends is detected. The position of the second image carrier in the movement direction of the carrier or the second image carrier so that the amount of deviation in the movement direction of the carrier at the proportionally distributed detection position is reduced. an image forming apparatus characterized by comprising control means for controlling the peripheral speed of the body, the. The first scale forming means forms an electrostatic image for each predetermined number of scanning lines on the first image carrier using the end of the scanning line of the first toner image in the main scanning direction, and Each time the electrostatic image is read by an antenna-type potential sensor in the vicinity of the transfer portion of one toner image, a magnetic scale is recorded on the magnetic track of the carrier,
The second scale forming means forms an electrostatic image for each predetermined number of scanning lines on the second image carrier using an end of the scanning line of the second toner image in the main scanning direction .
The image forming apparatus according to claim 1, characterized in that. A carrier capable of carrying and moving a toner image formed using a scanning line;
Formed on the first image bearing member for rotating the first toner image having an edge which is inclined obliquely to the scanning lines, a first image forming unit to be transferred to the conveying member,
Formed on the second image bearing member for rotating the second toner image having an edge slope equal to the first toner image, a second image forming unit to be transferred to the conveying member,
At a predetermined detection position in the width direction orthogonal to the moving direction of the conveying member, and capable of detecting sensing means and said second toner image and the first toner image,
Based on the time difference the detection means detects the second toner image and the first toner image, second formed on the first toner image and the second image bearing member formed on said first image bearing member Adjusting means for adjusting the relative position of the toner image in the main scanning direction ;
First scale associating means for associating a scanning line for forming a first toner image on the first image carrier with a first scale provided in advance at a predetermined first position at both ends of the conveyance body in the width direction. When,
A second scale forming means for forming a second graduation in the predetermined second position of the both ends in the width direction orthogonal to the direction of rotation of the second image bearing member in association with the scanning lines forming the second toner image,
First scale detecting means for detecting the first scale;
Second scale detection means for detecting the second scale;
During non-image formation, according to the positional relationship between the detection position, the first position, and the second position, the amount of shift in the moving direction of the transport body between the first scale and the second scale at both ends is detected. The position of the second image carrier in the movement direction of the carrier or the second image carrier so that the amount of deviation in the movement direction of the carrier at the proportionally distributed detection position is reduced. an image forming apparatus characterized by comprising control means for controlling the peripheral speed of the body, the. The second image forming unit is located at the center of the interval between the two first toner images transferred by the first image forming unit at a distance corresponding to the scanning line twice the predetermined number in the rotation direction of the conveyance body. Transfer a second toner image having the same shape as the toner image,
The adjusting means includes a time from when the detecting means detects the first toner image to the time when the second toner image is detected, and after that time after the second toner image is detected until the first toner image is detected. In accordance with the difference with time, the second image forming unit adjusts the position in the main scanning direction of the image written on the second image carrier ,
The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. At the time of non-image formation, the one first image forming unit and the plurality of second image forming units arrange parallel linear toner images inclined in one direction with respect to the scanning line on the conveyance body. By controlling the first image forming unit and the plurality of second image forming units, the relative position of the toner image in the main scanning direction in one of the first image forming unit and the plurality of second image forming units is determined. Comprising execution means for executing an adjustment mode for adjustment ;
The image forming apparatus according to any one of claims 1 to 4, characterized in that. Wherein, at the time of image forming, the conveyance of the widthwise central position of the carrier and the first position in accordance with the positional relationship between the second position, and the first graduation and the second graduation at both ends the shift amount of the moving direction of the body prorating the previous SL in central position, so as to reduce the deviation of the moving direction of the conveying member at the central position the proportional allocation, the in the direction of movement of the conveying member first controlling the peripheral speed position or the second image bearing member of the secondary image bearing member,
The image forming apparatus according to claim 1 , wherein the image forming apparatus is an image forming apparatus.

Images