JP2010072469A - Image processor, shift correction controller, and shift amount correction implementing program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To more rapidly and appropriately perform color shift correction regardless of the meandering of a belt compared with the case not having this configuration. <P>SOLUTION: By arithmetically calculating color shift between colors and removing a component (cyclic variation) of the color shift caused by a rotational cycle of a photoreceptor drum 116 by movement averaging processing, a meandering portion of the belt is extracted. The shift amount of the meandering portion of the belt includes a fixed portion and a varied portion to be settled before long. The varied portion is predicted by obtaining a difference caused by a time difference without waiting until the varied portion is settled. By removing the predicted varied portion of the meandering of the belt, a DC component, that is, a quantitative shift amount being the total sum of a belt meandering fixed portion+component by relative positions between attached components is extracted to set a correction value. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image processing apparatus, a deviation amount correction control apparatus, and a deviation amount correction execution program.

  The image processing apparatus includes a conveyance system using a belt (conveyance belt, intermediate transfer belt). In an image processing apparatus provided with a conveyance system using a conveyance belt that conveys recording paper, each color formed by the development apparatus facing each color developing device (photosensitive drum, etc.) arranged along the conveyance direction. A color image is obtained by transferring the toner on the recording paper.

  On the other hand, in an image processing apparatus provided with a conveyance system using an intermediate transfer belt, toner images from the developing devices of the respective colors are transferred onto the intermediate transfer belt in advance (primary transfer), and then transferred to a recording sheet (second). (Next transfer) to obtain a color image.

  The belt meanders at the start of driving, and proposals have been made to converge this meandering actively or passively (for example, see Patent Documents 1 to 3).

Patent Document 4 discloses an invention relating to color misregistration in a steady state in which belt meandering exhibits periodic behavior. In correction of this color misregistration, the meandering of the belt implicitly converges. It is assumed.
JP-A-10-109776 JP 2001-125390 A JP-A-4-121337 Japanese Patent No. 3068109

  The present invention provides an image processing apparatus, a deviation amount correction control apparatus, and a deviation amount correction execution program that can perform appropriate deviation correction quickly and without depending on the meandering of the belt as compared with the case without this configuration. Is the purpose.

  According to the first aspect of the present invention, an image forming unit that forms an image by superimposing and transferring a plurality of images developed and developed by a developer based on image data onto a recording sheet; and Conveying means for conveying at least one of the recording paper and the image to the transfer position of the image forming unit via a belt, and meandering generated after the start of movement of the belt is converged as the belt moves. Meandering converging means, total deviation amount detecting means for detecting a total deviation amount between the images including all transfer position deviation factors based on the image formed on the recording paper by the image forming unit, and the image A meandering deviation detecting unit for detecting a deviation amount between periodic images in the forming unit, and a meandering deviation for detecting a deviation amount due to meandering at a specific time based on a meandering convergence characteristic time curve based on the meandering convergence unit. From the total deviation detected by the detection means and the total deviation detection means at the specific time, the period deviation detected by the period deviation detection means and the meander deviation detected by the meander deviation detection means A deviation amount calculation means for calculating a deviation amount quantitatively generated at the time of convergence of the belt by subtracting the amount; and a cyclic deviation detected after the meandering convergence and detected by the periodic deviation amount detection means. Correction means for correcting the transfer position of the image onto the recording paper based on the amount and the quantitative deviation amount calculated by the quantitative deviation amount calculation means.

  According to a second aspect of the present invention, in the first aspect of the present invention, the plurality of images transferred onto the recording sheet are images of at least two different colors, and the correction means The deviation between the colors is corrected.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the image forming unit outputs a light beam whose lighting is controlled according to image data while deflecting the light beam in the main scanning direction. , When irradiating the light beam toward the image carrier that is uniformly charged in advance, an electrostatic latent image is formed on the image carrier by moving the image carrier in the sub-scanning direction, The electrostatic latent image is developed with a toner developer to form a toner image, and the toner image is transferred to the recording paper.

  According to a fourth aspect of the present invention, in the invention of the third aspect, a C (cyan) color toner, an M (magenta) color toner, and a Y toner that obtain a full color image by transferring the toner image in an overlapping manner. It is formed of (yellow) color toner and K (black) color toner, and the correction means uses any one of the colors as a reference color and corrects a deviation amount from the reference color.

  According to a fifth aspect of the present invention, there is provided a total shift amount detecting means for detecting a total shift amount between images including all shift factors based on an image formed on a recording sheet by an image forming unit, and the image Periodic deviation amount detecting means for detecting a deviation amount between periodic images in the forming unit, and meandering generated after the start of movement of the belt that conveys at least one of the recording paper and the image to the transfer position of the image forming unit A meandering deviation amount detecting means for detecting a deviation amount due to meandering at a specific time based on a meandering convergence characteristic time curve based on a meandering convergence means for converging as the belt moves, and from the total deviation amount The period deviation amount and the meander deviation amount are subtracted to calculate a deviation amount quantitatively generated at the time of convergence of the belt, and is executed after the meander convergence, the period And a, a correction means for correcting the transfer position on the recording paper an image based on which the amount of the in and the quantitative amount of deviation.

  According to a sixth aspect of the present invention, in the invention of the fifth aspect, the plurality of images to be transferred onto the recording sheet are images of at least two colors having different colors, and the correcting means The deviation between the colors is corrected.

  According to a seventh aspect of the invention, in the invention of the fifth or sixth aspect, the image forming unit outputs a light beam controlled to be turned on according to image data while deflecting in the main scanning direction. , When irradiating the light beam toward the image carrier that is uniformly charged in advance, an electrostatic latent image is formed on the image carrier by moving the image carrier in the sub-scanning direction, The electrostatic latent image is developed with a toner developer to form a toner image, and the toner image is transferred to the recording paper.

  According to an eighth aspect of the present invention, in the seventh aspect of the present invention, the toner image is a C (cyan) color toner, M (magenta) color toner, and Y It is formed of (yellow) color toner and K (black) color toner, and the correction means uses any one of the colors as a reference color and corrects a deviation amount from the reference color.

  According to the ninth aspect of the present invention, based on the image formed on the recording paper by the image forming unit, the total shift amount between the images including all the shift factors is detected, and the periodicity in the image forming unit is detected. The amount of deviation between the images is detected, and meandering that occurs after the start of movement of the belt that conveys at least one of the recording paper and the image to the transfer position of the image forming unit is converged as the belt moves. Based on the meandering convergence characteristic time curve based on the meandering convergence means, the amount of deviation due to meandering at the time of deviation correction is detected, and the periodic deviation amount and the meandering deviation amount are subtracted from the total deviation amount. A deviation amount correction that causes a computer to calculate a deviation amount that occurs quantitatively when the belt converges and to correct a transfer position of an image onto a recording sheet based on the periodic deviation amount and the quantitative deviation amount. Fruit Is a program.

  According to a tenth aspect of the present invention, in the invention according to the ninth aspect, the plurality of images transferred to be overlapped on the recording sheet are images of at least two different colors, and the correcting means The deviation between the colors is corrected.

  According to an eleventh aspect of the present invention, in the invention according to the ninth or tenth aspect, the image forming unit outputs a light beam whose lighting is controlled according to image data while deflecting in the main scanning direction. , When irradiating the light beam toward the image carrier that is uniformly charged in advance, an electrostatic latent image is formed on the image carrier by moving the image carrier in the sub-scanning direction, The electrostatic latent image is developed with a toner developer to form a toner image, and the toner image is transferred to the recording paper.

  According to a twelfth aspect of the present invention, in the invention of the eleventh aspect, a C (cyan) color toner, an M (magenta) color toner, a Y ( The toner is formed of yellow) toner and K (black) toner, and the correction unit uses any one of the colors as a reference color, and corrects a deviation amount from the reference color.

  According to the first aspect of the present invention, as compared with the case where the present configuration is not provided, it is possible to perform appropriate deviation correction quickly without depending on the belt meandering.

  According to the second aspect of the present invention, color-specific shift correction (color shift correction) is possible as compared with the case where this configuration is not provided.

  According to the third aspect of the present invention, it is possible to correct a positional deviation or a color deviation between toner images formed by light beam scanning exposure and toner development, as compared with the case without this configuration.

  According to the fourth aspect of the present invention, as compared with the case where the present configuration is not provided, it is possible to correct color misregistration of a full-color image formed by superimposing and transferring CMYK colors.

  According to the fifth aspect, as compared with the case where the present configuration is not provided, it is possible to perform appropriate deviation correction quickly without depending on the belt meandering.

  According to the sixth aspect of the present invention, color-specific shift correction (color shift correction) is possible as compared with the case without this configuration.

  According to the seventh aspect of the present invention, it is possible to correct a positional shift or a color shift between toner images formed by light beam scanning exposure and toner development, as compared with the case without this configuration.

  According to the eighth aspect of the present invention, it is possible to correct color misregistration of a full color image formed by superimposing and transferring CMYK colors as compared with the case without this configuration.

  According to the ninth aspect, as compared with the case where the present configuration is not provided, it is possible to perform appropriate deviation correction quickly without depending on the belt meandering.

  According to the tenth aspect of the present invention, color-specific misregistration correction (color misregistration correction) is possible as compared with the case where the present configuration is not provided.

  According to the eleventh aspect of the present invention, it is possible to correct a positional shift or a color shift between toner images formed by light beam scanning exposure and toner development, as compared with the case without this configuration.

  According to the twelfth aspect of the present invention, it is possible to correct color misregistration of a full color image formed by superimposing and transferring CMYK colors as compared with the case without this configuration.

(Overall configuration of image forming apparatus)
FIG. 1 is a diagram showing a configuration of an image processing apparatus 110 according to the present embodiment of the present invention.

  The image processing apparatus 110 includes four developing devices 120 that perform full color image formation with four color toners (yellow (Y), magenta (M), cyan (C), and black (K)) in the vertical direction corresponding to each color. Are arranged.

  The toners Y, M, C, and K are not particularly limited by the manufacturing method, and various toners can be used.

  Here, the developing device 120 applies the photosensitive drum 116, the charging roll 118 disposed around the photosensitive drum 116, the erase lamp 122, and the electrostatic latent image formed on the photosensitive drum 116. And a developing device 10 (10A, 10B, 10C, 10D) for developing the toner of each color.

  On the other hand, at the lower part of the image processing apparatus 110, a paper feed cassette 124 in which the recording paper P is stored is provided. In the vicinity of the paper feed cassette 124, a pickup roll 126 that feeds the recording paper P at a predetermined timing is provided.

  The pickup roll 126 feeds the recording paper P from the paper feed cassette 124 and transports the recording paper P to the transport device 144 that transports the recording paper P to the developing device 120 via the transport roll 128, the paper transport path 132, and the registration roll 130.

  The developing device 120 is arranged in the order of the aforementioned Y, M, C, and K colors from the upstream side (the lower side of the paper surface) of the paper transport path 132. On the left side of the developing device 120 in FIG. 1, an optical scanning device 20 that irradiates the developing device 120 with scanning light is disposed.

  The optical scanning device 20 is mainly provided with a semiconductor laser (not shown) and a polygon mirror 23, and the light from the semiconductor laser is deflected and scanned by the polygon mirror 23 and irradiated to the photosensitive drum 116. As a result, an electrostatic latent image corresponding to the image information is formed on the photosensitive drum 116.

  The conveyance device 144 includes a pair of tension rolls 146 and 148 provided along the side wall 110 </ b> A of the image processing apparatus 110, and a conveyance belt 150 wound around the tension rolls 146 and 148.

  At least one of the tension rolls 146 and 148 functions as a part of a mechanism for converging the meandering of the conveyor belt 150.

  For example, in the case of active control, one or both of the tension rolls 146 and 148 are inclined to change the degree of tension in the axial direction of the conveyor belt, and the conveyor belt 150 intersects the drive direction. Move in the direction to converge the meander.

  Further, for example, in the case of passive control, a roller member or the like for pushing back the conveying belt meandering and contacting the axial ends of the stretching rolls 146 and 148 is attached, or the stretching rolls 146 and 148 themselves are attached. The meandering of the conveyor belt 150 is converged by using a so-called crown shape or the like.

  A suction roll 154 is disposed in the vicinity of the tension roll 146, and the recording paper P is electrostatically attracted to the transport belt 150 by applying a bias voltage to the suction roll 154. The tension roll 148 is rotated by a motor (not shown) and moves the conveyor belt 150 along the side wall 110A. A density sensor 155 that detects the density of the reference patch is provided at a position facing the stretching roll 148 with the conveyance belt 150 interposed therebetween.

  The density sensor 155 reads a reference patch recorded on the recording paper P, detects a shift between colors (so-called color registration), and feeds back to an optical scanning system that controls the semiconductor laser, for example, to shift timing. Corrections between colors (color registration correction) are made.

  The color misregistration includes various factors. In particular, the color misregistration in the main scanning direction converges the periodic color misregistration of the photosensitive drum and the meandering of the conveyance belt 150. There is a relative positional shift with respect to the photosensitive drum 116 later (that is, after stabilization). Of course, when the conveying belt 150 is meandering, a shift between colors due to the meandering is also added. The correction of the shift between colors will be described later.

  Transfer rolls 152 are disposed at positions on the inner peripheral side of the conveyance belt 150 and facing the photosensitive drums 116 of the respective colors. Each transfer roll 152 sequentially transfers the toner images Y, M, C, and K formed on the photosensitive drum 116 onto the recording paper P conveyed by the conveyance belt 150.

  Each transfer roll 152 sequentially transfers the toner images Y, M, C, and K of the reference patch formed on the photosensitive drum 116 to the conveyance belt 150. Here, the reference patch is used to measure the toner density in the developing device 10 and the transfer position of the reference patch to the conveyance belt. Specifically, image forming conditions such as toner supply to the developing device 10 and exposure amount are controlled according to the density of the reference patch detected by the density sensor 155. The reference patch position is measured by measuring the timing at which each reference patch passes through the density sensor 155, and the amount of deviation is detected. An image formation start timing correction amount and a main scanning direction magnification shift correction amount are determined according to the measured shift amount. The fixing device 156 fixes the toner image transferred to the recording paper P. The discharge roll 158 discharges the recording paper P on which the toner image is fixed to the discharge tray 160.

  The control unit 166 controls the entire apparatus. The control unit 166 controls the optical scanning device 20 and the developing device 10 based on, for example, image data input from the outside or the output of the density sensor 155.

  As shown in FIG. 2, the control unit 166 includes a microcomputer 50. The microcomputer 50 includes a CPU 52, a RAM 54, a ROM 56, an I / O (input / output unit) 58, and a bus 60 such as a data bus or a control bus for connecting them.

  Connected to the I / O 58 is an image formation control management unit 200 for managing and controlling the image forming unit of the conveying device 144, the developing device 10, the optical scanning device 20 and the like (see FIG. 1) in the image processing apparatus 110. Has been. The image formation control management unit 200 may be configured to be directly connected to the bus 60 instead of the I / O 58.

  A UI (user interface) 62 is connected to the I / O 58. The UI 62 has a function of receiving an input instruction from the user and notifying the user of information related to image processing.

  Further, a hard disk 64 is connected to the I / O 58. The hard disk 64 has a role of storing the read image data, for example.

  Here, when correcting the shift between colors, basically, the reference patch is written on the recording paper P, and the reference patch is read by the density sensor 155 to determine the shift between the colors. However, the detection timing is an important factor in detecting the shift between the colors.

  In general, color misregistration correction (color registration correction) is performed after the installation of the image processing apparatus 110 (initial installation), when replacing parts such as a belt unit, and removing paper jams during image formation processing (jam removal). Thereafter, when the temperature and humidity of the environment in which the image processing apparatus is installed changes beyond a specified value, such as every predetermined image formation processing amount (PV amount), the conveyance belt 150 is once stopped and then restarted. There are many.

  For this reason, conventionally, after the meandering of the conveyor belt 150 is converged, the correction of the shift between colors is performed.

  On the other hand, in the present embodiment, it is possible to execute the correction of the shift between colors before the meandering of the conveyor belt 150 converges.

  The CPU 52 of the control unit 166 reads a program for performing deviation correction control stored in the ROM 56, and executes processing to be described later. It is also possible to provide the program by storing it in a transportable storage medium such as a CD-ROM. The program may be stored in the hard disk 64.

  FIG. 3 shows a functional block diagram for color misregistration amount analysis control for each factor at the time of color registration correction in the control unit 166. The functional block diagram of FIG. 3 does not limit the hardware configuration.

  The image formation control management unit 200 is connected to the image formation state determination unit 202. The image forming unit state determination unit 202 receives image forming unit information from the image forming control management unit 200 and determines whether it is the color registration adjustment time.

  The image forming unit state determination unit 202 is connected to the patch data formation instruction unit 204. When the color registration adjustment time is determined, the image forming unit state determination unit 202 gives information indicating that it is the color registration adjustment time to the patch data formation instruction unit 204. Output.

  The patch data formation instructing unit 204 that has received information indicating that it is the color registration adjustment time instructs the image formation control management unit 200 to perform image formation processing based on the patch data. A patch data density reading instruction unit 206 is connected to the image formation control management unit 200.

  When the patch data density reading instruction unit 206 receives patch data formation completion information from the image formation control management unit 200, the patch data density reading instruction unit 206 uses the density sensor 155 from the density sensor operation management control unit 208 via the image formation control management unit 200. Instructs reading of patch data.

  The density sensor operation management control unit 208 is connected to the density data acquisition unit 210. The density data acquisition unit 210 acquires the detection value (density data) from the density sensor 155 via the density sensor operation management control unit 208 and sends it to the density data analysis unit 212.

  The density data analysis unit 210 analyzes the position of the patch data of each color (CMYK), and the analysis data is sent to the displacement amount calculation unit 214.

  The displacement amount calculation unit 214 has a position displacement amount for each color (component due to the photoreceptor period (period variation), belt meander component (fixed amount A, variation amount B), and component due to the relative position between the mounted components (fixed amount). ) Is included (Ec (t), Em (t), Ey (t), Ek (t)).

  The displacement amount calculation unit 214 is connected to the inter-color difference calculation unit 216. The inter-color difference calculation unit 216 calculates a color shift between colors. In the following, the fixed portion may be collectively referred to as “quantitative (color) deviation amount”.

  For example, if the color shift between the M color and the Y color is Emy, Emy can be expressed as Em (t) -Ey (t). This is because the time element (t) varies depending on time.

  The inter-color difference calculation unit 216 is connected to the moving average processing unit 218. The moving average processing unit 218 is executed to remove the above-described color misregistration component (cycle fluctuation) due to the rotation cycle of the photosensitive drum 116.

  That is, by obtaining an average for each cycle T (2π / ω), it is possible to cancel the cycle variation of the photosensitive drum 116 that varies with a sine wave. Note that (ω is an angular velocity and can be expressed as 2πf (f is a frequency), and it is understood that T = 1 / f).

  The moving average processing unit 218 cancels out the period fluctuation caused by the photosensitive drum 116, and as a result, extracts the meandering belt (Fmy (t)).

  Here, the fixed portion A and the variation B are mixed in the color shift amount Fmy (t) of the belt meander, and it is necessary to remove the variation.

  Therefore, the moving average processing unit 218 sends color deviation amount (Fmy (t)) data for the belt meandering to the belt fluctuation B calculation unit 220.

  A calculation time setting unit 222 is connected to the belt variation B calculation unit 220, and preset calculation times t1 and t2 are read out. The calculation time is relatively earlier at t1 and later at t2.

  The belt fluctuation amount calculation unit 220 calculates the amount of color misregistration for the belt meandering at the calculation times t1 and t2 (Fmy (t1), Fmy (t2)), and calculates the difference (Fmy (t2) −Fmy ( t1)), the variation B is obtained.

  The belt fluctuation calculation unit 220 is connected to the DC component calculation unit 224, and the belt fluctuation calculation unit 220 sends the calculation result (fluctuation B) to the DC component calculation unit 224.

  As a result, since the variation B is known in the DC component calculation unit 224, a quantitative color misregistration amount (quantitative misregistration amount) relating to the DC component, that is, the component due to the relative position between the belt meandering fixed portion and the mounted parts. Will be extracted.

  The DC component calculation unit 224 is connected to the correction calculation unit 226. The correction calculation unit 226 calculates correction values Dc, Dm, Dy, and Dk based on the extracted color shift amount (quantitative shift amount) of the DC component, and sends the result to the correction value output unit 228.

  The correction value output unit 228 is connected to the image formation control management unit 200, and sends the received correction value to the image formation control management unit 200. As a result, the image formation control management unit 200 executes the exposure process in a state where the quantitative deviation amount (DC component) is added (corrected) (for example, in the case of a laser, the light emission timing is shifted based on the image data). etc).

  The operation of the present embodiment will be described below with reference to the flowchart of FIG.

  In step 250, image formation information is acquired, and then in step 252, it is determined based on the image formation information whether it is time to adjust color registration. If the determination in step 252 is negative, this routine ends.

  If an affirmative determination is made in step 252, the process proceeds to step 254 to instruct patch data formation, and then proceeds to step 256 to output a patch data density reading instruction to the image formation control management unit 200. Migrate to

  In step 258, it is determined whether or not density information has been acquired. If an affirmative determination is made, the process proceeds to step 260, where the displacement amount (Ec (t), Em (t), Ey (t) of each color (CMYK) is determined. , Ek (t)) is calculated by a predetermined sampling number.

  In the next step 262, a shift amount between colors (for example, Emy between M and Y colors) is calculated (for example, Emy = Em (t) −Ey (t)).

  In the next step 264, the moving average process is executed based on the period T. By this moving average process, the period fluctuation caused by the shake of the photosensitive drum 116 is removed.

  In the next step 266, the calculation timings t1 and t2 for calculating the data after moving average processing (data obtained in the step 264) from which the period variation is removed with a time difference are read, and the process proceeds to step 268. The difference in time difference is calculated (B = Fmy (t−2) −Emy (t−1)).

  Here, the obtained data is the variation B of the color misregistration due to the meandering of the conveyor belt 150. In the next step 270, the color misregistration variation of the relational expression of Fmy (formula (7) described later). Substitute into B. As a result, a color shift amount of the DC component is obtained.

  In the next step 272, the DC component correction value is calculated, and then the process proceeds to step 274 to send the correction value to the image formation control management unit 200, and this routine ends.

  In the above, the color shift between the M color and the Y color is taken as an example, but the same applies to other colors. If any color (Y color) is set as the reference color, the C color is assumed. It is only necessary to correct the color misregistration between the Y color and the K color and the Y color (the correction value of the Y color may be “0”).

  On the other hand, when the reference position is determined in advance, after correcting the color misregistration of the four colors, correction between the reference position and the reference position may be added.

  Next, details of an example of the color registration misalignment correction operation of the present embodiment will be described.

  As described above, in the conventional color registration misalignment correction operation in the main scanning direction, it is necessary to perform the belt rotation operation until the belt meandering converges and stabilizes. Therefore, the color registration misalignment correction operation is completed and the image forming operation is completed. There was a problem that it took a long time to become possible.

  In the above-described embodiment, even when the worst meandering state is assumed, such as when the image processing apparatus 110 is installed or the belt unit is replaced, the main belt is not used until the meandering is converged and stabilized. Color registration misalignment correction operation in the scanning direction can be performed.

  Hereinafter, for simplification, the color shift between the Y color and the M color will be described, but other color shifts can be handled in the same manner.

  FIG. 5 shows a case where the MY inter-color shift in the main scanning direction obtained based on the patch data detected by the density sensor 155 is only a DC component that does not change with time.

This component is mainly caused by the relative position between the exposure means and the photosensitive member being shifted between colors.
This component is any amount detected by the color registration error detection means in order to be corrected by the color registration error correction means.

  FIG. 6 shows a case where the MY inter-color shift in the main scanning direction obtained based on the patch data detected by the density sensor 155 is only the shake component of the photosensitive drum 116.

  Since this component is not corrected by the color registration error correction unit, it is any amount removed when detected by the color registration error detection unit.

  FIG. 7 shows a case where the MY color misalignment in the main scanning direction obtained based on the patch data detected by the density sensor 155 is only the meandering component of the belt.

  This component exists when the belt meandering is not converged and stabilized during the color registration misalignment correction operation, but disappears when the belt meandering converges stably during the image forming operation, and is corrected by the color registration misalignment correcting means. Therefore, it is any amount removed when detected by the color registration deviation detecting means.

  In FIG. 8, the MY color misalignment in the main scanning direction obtained based on the patch data detected by the density sensor 155 is a combination of the above-described DC component, photoconductor shake component, and belt meander component. Indicates the case where there was.

  Next, an operation for extracting a DC component to be originally detected from the combined waveform detected by the color registration deviation detecting means according to the present embodiment will be described.

  First, the removal of the photosensitive member shake component will be described.

  FIG. 9 shows the waveform of the MY intercolor shift obtained based on the patch data detected by the density sensor 155 and the waveform after removal of the photosensitive member shake component.

  Since the rotational angular velocity ω of the photosensitive member is already known, the shake component of the photosensitive member can be removed by subjecting the detected waveform to a moving average process at a photosensitive member shake one rotation period 2π / ω.

  Note that it is also possible to eliminate the difference by calculating the difference between the detection information at an arbitrary timing and the detection information after a period of 2π / ω in the same phase state.

  Next, the removal of the belt meandering component will be described.

  As shown in FIG. 10, the actual belt meandering state can be accurately estimated by approximating the behavior of the belt edge by the following equation.

In the above formula,
y (0) = AB is the initial belt position (t = 0)
y (∞) = A is the belt position after convergence stabilization (t = ∞)
y (∞) −y (0) = B is the amount of displacement due to the belt meandering.

Since the values of A and B differ depending on the installation of the image forming apparatus, the replacement of the belt unit, the stable convergence of the belt meandering immediately after the image forming operation, and the individual variation, the correction operation of the color registration misalignment correction means Sometimes it is an unknown value.

  On the other hand, the value of k becomes constant when the belt tension conditions (various physical properties such as tension roll arrangement, tension roll diameter, tension tension, etc.) in the image forming apparatus are determined, and can be obtained in advance by experiments. it can.

  Here, the elements that determine the time constant k are shown.

  Therefore, the value of k is known during the correction operation of the color registration misalignment correction unit.

  Now, the amount of color misregistration from the ideal position of Y color and M color is expressed by the following equation.

  Here, when the amount of misregistration between MY colors is Emy,

In order to remove the above-mentioned photosensitive member shake component, Emy is subjected to a moving average process at T = 2π / ω, and this is defined as Fmy.
At this time, the photosensitive member shake component disappears by the moving average process, and the belt meandering component is

  It becomes.

  So Fmy

Now, at a certain time t ₁ , t ₂ , Fmy (t ₁ ) and Fmy (t ₂ ) are obtained by performing the above-described arithmetic processing on the color registration amount detected by the color registration detection unit. Assuming that

  The positional deviation amount B due to the belt meandering can be obtained from the above equation, and by substituting this into the equation (7), the DC component of the deviation amount Dm-Dy, that is, the MY intercolor deviation can be obtained.

  FIG. 11 shows a waveform after the photosensitive member shake component is removed, and further after the belt meander component is removed.

  So far, the shift amount between the two colors of Y and M has been described, but the shift amount between any two colors can be detected by the same procedure.

  In the present embodiment, the limiting wave is integrated (area average) in the moving average process performed to remove the shake of the photosensitive drum 116, but a plurality of samplings are performed and the total value is obtained. May be a simple average calculation such as dividing by the number of samplings.

  In the present embodiment, the following embodiments can be considered.

  The belt is a recording paper transport belt for transporting the recording paper to a transfer position with a plurality of the images, or a secondary transfer position for secondary transfer from a primary transfer position for primary transfer of the plurality of images to the recording paper. At least one of the intermediate transfer belts to be conveyed.

  In this embodiment, the image processing apparatus 110 using the recording paper conveyance belt 150 is described as an example. However, the intermediate transfer belt on which the toner images of the respective colors from the photosensitive drums 116 are primarily transferred so as to overlap each other. It can also be applied to color misregistration correction by meandering. In other words, this intermediate transfer belt is also provided with a so-called misalignment mechanism (mechanism for converging the belt meandering). Color registration correction may be performed.

  Further, the image processing apparatus may be a combination of the recording paper conveyance belt 150 and the intermediate transfer belt.

1 is a diagram illustrating a configuration of an image forming apparatus according to an exemplary embodiment. It is a block diagram which shows the hardware constitutions of the control unit which concerns on this Embodiment. It is a functional block diagram for color misregistration amount analysis control according to factors at the time of color registration correction in the control unit. 7 is a flowchart illustrating color misregistration amount analysis control for each factor during color registration correction. FIG. 10 is a characteristic diagram when the MY color misregistration in the main scanning direction is only a DC component that does not change with time. FIG. 10 is a characteristic diagram in the case where the MY color misregistration in the main scanning direction is only the shake component of the photosensitive drum 116; FIG. 10 is a characteristic diagram when the MY color misregistration in the main scanning direction is only the meandering component of the belt. FIG. 10 is a characteristic diagram in a case where the MY color misregistration in the main scanning direction is a combination of the above-described DC component, photoconductor shake component, and belt meander component. FIG. 6 shows a waveform of an MY intercolor shift and a waveform after removal of a photosensitive member shake component. It is a conveyance belt meandering convergence displacement characteristic view. It is a waveform after the photosensitive member shake component is removed, and further a waveform after the belt meander component is removed.

Explanation of symbols

10 Developing Device 20 Optical Scanning Device 50 Microcomputer 52 CPU
54 RAM
56 ROM
58 I / O
60 bus 62 UI
64 Hard disk 110 Image processing device 116 Photosensitive drum 144 Conveying device 156 Fixing device 160 Ejection tray 166 Control unit 200 Image formation control management unit 202 Image formation state determination unit 204 Patch data formation instruction unit 206 Patch data density reading instruction unit 208 Density sensor Operation management control unit 210 Density data acquisition unit 212 Density data analysis unit 214 Displacement amount calculation unit 216 Inter-color difference calculation unit 218 Moving average processing unit 220 Belt fluctuation B calculation unit 222 Calculation time setting unit 224 DC component calculation unit 226 Correction calculation Part 228 correction value output part

Claims (12)

An image forming unit that forms an image by transferring a plurality of images developed and developed by a developer based on image data onto a recording sheet; and
Conveying means for conveying at least one of the recording paper and the image to a transfer position of the image forming unit via a belt;
Meandering converging means for converging meandering generated after the start of movement of the belt as the belt moves;
Based on the image formed on the recording paper by the image forming unit, total deviation amount detection means for detecting the total deviation amount between the images including all the transfer position deviation factors;
A periodic shift amount detecting means for detecting a shift amount between periodic images in the image forming unit;
Based on the meandering convergence characteristic time curve based on the meandering convergence means, meandering deviation amount detection means for detecting the deviation amount due to meandering at a specific time;
Subtract the period deviation detected by the period deviation detection means and the meander deviation detected by the meander deviation detection means from the total deviation detected by the total deviation detection means at the specific time. A quantitative deviation amount calculating means for calculating a deviation amount quantitatively generated at the time of convergence of the belt;
Based on the periodic deviation amount detected by the periodic deviation amount detecting means and the quantitative deviation amount calculated by the quantitative deviation amount calculating means, which is executed after the meandering is converged, the transfer position of the image onto the recording sheet is determined. Correction means for correcting;
An image processing apparatus.   The image processing apparatus according to claim 1, wherein the plurality of images transferred and superimposed on the recording sheet are images of at least two different colors, and the correction unit corrects the shift between the colors.   When the image forming unit outputs a light beam whose lighting is controlled according to image data while deflecting in the main scanning direction, and irradiates the light beam toward an image carrier that is uniformly charged in advance. The electrostatic latent image is formed on the image carrier by moving the image carrier in the sub-scanning direction, the electrostatic latent image is developed with a toner developer, and the toner image is recorded in the recording medium. The image processing apparatus according to claim 1, wherein the image processing apparatus transfers the image onto a sheet. The toner image is formed of C (cyan) color toner, M (magenta) color toner, Y (yellow) color toner, and K (black) color toner to obtain a full color image by being transferred in an overlapping manner,
The image processing apparatus according to claim 3, wherein the correction unit uses any one of the colors as a reference color and corrects a deviation amount from the reference color. Based on the image formed on the recording paper by the image forming unit, total deviation amount detecting means for detecting the total deviation amount between the images including all the deviation factors;
A periodic shift amount detecting means for detecting a shift amount between periodic images in the image forming unit;
A meandering convergence characteristic based on meandering convergence means for converging meandering generated after the start of movement of a belt that conveys at least one of the recording paper and the image to a transfer position of the image forming unit. A meandering deviation amount detecting means for detecting a deviation amount due to meandering at a specific time based on a time curve;
Subtracting the periodic deviation amount and the meandering deviation amount from the total deviation amount, thereby calculating a deviation amount calculating means for calculating a deviation amount quantitatively generated at the time of convergence of the belt;
Correction means that is executed after convergence of the meandering, and corrects the transfer position of the image to the recording paper based on the periodic deviation amount and the quantitative deviation amount;
A deviation amount correction control device having   6. The deviation amount correction control apparatus according to claim 5, wherein the plurality of images transferred onto the recording sheet are images of at least two different colors, and the correction unit corrects the deviation between the colors. .   When the image forming unit outputs a light beam whose lighting is controlled according to image data while deflecting in the main scanning direction, and irradiates the light beam toward an image carrier that is uniformly charged in advance. The electrostatic latent image is formed on the image carrier by moving the image carrier in the sub-scanning direction, the electrostatic latent image is developed with a toner developer, and the toner image is recorded in the recording medium. The deviation amount correction control apparatus according to claim 5 or 6, wherein the shift amount correction control apparatus is a process of transferring to a sheet. The toner image is formed of C (cyan) color toner, M (magenta) color toner, Y (yellow) color toner, and K (black) color toner to obtain a full color image by being transferred in an overlapping manner,
The deviation amount correction control apparatus according to claim 7, wherein the correction unit uses any one of the colors as a reference color and corrects a deviation amount from the reference color. Based on the image formed on the recording paper by the image forming unit, the total deviation amount between each image including all deviation factors is detected,
Detecting a shift amount between periodic images in the image forming unit;
A meandering convergence characteristic based on meandering convergence means for converging meandering generated after the start of movement of a belt that conveys at least one of the recording paper and the image to a transfer position of the image forming unit. Based on the time curve, detect the amount of deviation due to meandering when the amount of deviation is corrected,
By subtracting the period deviation amount and the meander deviation amount from the total deviation amount, a deviation amount quantitatively generated at the time of convergence of the belt is calculated,
A deviation amount correction execution program for causing a computer to correct a transfer position of an image onto a recording sheet based on the periodic deviation amount and the quantitative deviation amount.   The shift amount correction execution program according to claim 9, wherein the plurality of images transferred onto the recording sheet are images of at least two different colors, and the correction unit corrects the shift between the colors. .   When the image forming unit outputs a light beam whose lighting is controlled according to image data while deflecting in the main scanning direction, and irradiates the light beam toward an image carrier that is uniformly charged in advance. The electrostatic latent image is formed on the image carrier by moving the image carrier in the sub-scanning direction, the electrostatic latent image is developed with a toner developer, and the toner image is recorded in the recording medium. The deviation amount correction execution program according to claim 9 or 10, which is a process of transferring to a sheet. The toner image is formed of C (cyan) color toner, M (magenta) color toner, Y (yellow) color toner, and K (black) color toner to obtain a full color image by being transferred in an overlapping manner,
12. The shift amount correction execution program according to claim 11, wherein the correction unit uses any one of the colors as a reference color and corrects the shift amount with respect to the reference color.

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