Image forming apparatus, image forming system, and image forming method

Abstract

To accurately perform correction even if the magnification of an image is changed.SOLUTION: An image forming apparatus comprises: an image forming unit that performs image formation; a correction unit that corrects a deviation amount based on patterns formed by the image forming unit; a changing unit that changes the magnification of the patterns; and a calculation unit that calculates the deviation amount based on the magnification.SELECTED DRAWING: Figure 15

Description

Technical Field

[0001] The present invention relates to an image forming apparatus, an image forming system, and an image forming method.

Background Art

[0002] In image formation, a technique of performing correction using a pattern is known to prevent color misregistration and the like.

[0003] And the toner pattern density may vary according to the linear velocity of the secondary transfer belt. Therefore, the image forming apparatus finely adjusts the conveyance speed. Next, the image forming apparatus corrects the detection result of the toner image detection means based on the speed adjustment information. Further, the image forming apparatus corrects the image forming conditions from the correction result. In this way, a technique is known in which even when the linear velocity of the secondary transfer belt is finely adjusted, the pattern can be accurately detected on the secondary transfer belt (for example, see Patent Document 1).

Summary of the Invention

Problems to be Solved by the Invention

[0004] The conventional technique does not assume a case where an image is formed with the magnification of the image changed. Therefore, when correction is performed when the magnification of the image changes or the like, there is a problem that accurate correction cannot be performed.

[0005] An object of the present invention is to perform accurate correction even when the magnification of an image changes.

Means for Solving the Problems

[0006] To solve the above problems, an image forming apparatus according to an aspect of the present invention includes: a plurality of image forming units that perform image formation based on a set magnification; a detection unit that detects a plurality of patterns formed by the plurality of image forming units; a calculation unit that calculates a deviation amount between the plurality of patterns based on a detection result by the detection unit; A correction unit that corrects the image formation timing at which the plurality of image forming units form an image based on the amount of deviation is provided, The calculation unit When there is no change in the set magnification, the deviation amount is calculated as the difference between the detection time between the plurality of patterns detected by the detection unit when there is no change in the set magnification and the ideal time when there is no deviation amount between the plurality of patterns detected by the detection unit. When there is a change in the set magnification, the ideal detection time is corrected by multiplying the changed magnification due to the magnification change by the ideal time, and the difference between the detection time between the plurality of patterns detected by the detection unit and the corrected ideal time is calculated as the deviation amount. is characterized by this.

Advantages of the Invention

[0007] According to the present invention, correction can be accurately performed even when the magnification of the image changes.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Embodiments for Carrying Out the Invention

[0009] Hereinafter, specific examples will be described with reference to the accompanying drawings. Note that the embodiments are not limited to the specific examples described below.

[0010] [First Embodiment] For example, the image forming apparatus 100 is the following type of apparatus.

[0011] [Example of Image Forming Apparatus] FIG. 1 is a diagram showing an example of an image forming apparatus. For example, in order to perform image formation, the image forming apparatus 100 includes an image forming device 20 or the like as follows.

[0012] The image forming apparatus 100 includes four sets of light beam scanning devices 21 or the like in order to form a color image by overlapping four-color (yellow, magenta, cyan, black) images. Hereinafter, yellow is referred to as "Y", magenta as "M", cyan as "C", and black as "K".

[0013] The light beam scanning device 21 is driven and modulated according to image data and selectively emits a light beam. The emitted light beam is deflected by a polygon mirror 213 that rotates with a polygon motor as a drive source. Thereafter, the light beam passes through an fθ lens 214, is reflected by a folding mirror 215, and scans on the photosensitive drum 40. Details will be described later.

[0014] The image forming device 20 includes a charging unit 18, a developing unit 29, a transfer unit 62, a cleaning unit 63, and a static eliminator 19 around the photosensitive drum 40.

[0015] The image forming apparatus 100 performs an electrophotographic image forming process. Specifically, first, through charging, exposure, development, and transfer, the image forming apparatus 100 forms a toner image of the first color (Y color in this example) on the intermediate transfer belt 10. Then, the intermediate transfer belt 10 rotates by the first support roller 64, the second support roller 65, and the like.

[0016] Next, the image forming apparatus 100 forms toner images in the order of the second color (M color in this example), the third color (C color in this example), and the fourth color (K color in this example). In this way, the image forming apparatus 100 forms a color toner image in which four-color images are superimposed.

[0017] Furthermore, the image forming apparatus 100 transfers the toner image formed on the intermediate transfer belt 10 to the recording medium P being conveyed by the secondary transfer device 22. In this way, the image forming apparatus 100 can form a color toner image in which four-color toner images are superimposed on the recording medium P. Then, the image forming apparatus 100 fixes the toner image to the recording medium P by the fixing unit.

[0018] The intermediate transfer body cleaning unit 17 removes the toner image remaining on the intermediate transfer belt 10.

[0019] The secondary transfer device 22 is a device including the first sensor SN1, the second sensor SN2, and the like. The first sensor SN1 and the second sensor SN2 detect the pattern formed on the secondary transfer belt 23.

[0020] The first sensor SN1 and the second sensor SN2 are, for example, reflective optical sensors or the like.

[0021] Based on the detection results of the first sensor SN1 and the second sensor SN2, the deviation amounts in the conveyance direction and the orthogonal direction are calculated.

[0022] The secondary transfer device 22 may include a secondary transfer belt cleaning device 24 and the like.

[0023] Further, the image forming apparatus 100 may further include a toner bottle or the like.

[0024] FIG. 2 is a diagram showing an example of an optical beam scanning device. The figure shows the optical beam scanning device 21 from a top view point. For example, the optical beam scanning device 21 has the same configuration for other colors.

[0025] The LD control board 211 emits an optical beam. When the optical beam is emitted, the optical beam enters the polygon mirror 213 through the cylinder lens 212.

[0026] The polygon mirror 213 rotates. Then, due to the rotation of the polygon mirror 213, the optical beam is deflected.

[0027] The optical beam reflected by the polygon mirror 213 passes through the fθ lens 214, is reflected by the folding mirror 215, and scans on the photosensitive drum 40.

[0028] At the end during scanning, a synchronization mirror 216, a synchronization lens 217, a synchronization sensor 218, etc. are installed.

[0029] The optical beam that has passed through the fθ lens 214 is reflected by the synchronization mirror 216. The optical beam reflected by the synchronization mirror 216 is condensed by the synchronization lens 217. After being condensed, the optical beam enters the synchronization sensor 218.

[0030] When the synchronization sensor 218 detects the optical beam, the writing timing is determined. Thus, the synchronization sensor 218 is used for generating a synchronization detection signal or the like.

[0031] FIG. 3 is a diagram showing a configuration example for controlling an optical beam scanning device or the like. The figure shows one color. Therefore, the printer control device 1, the first sensor SN1, the second sensor SN2, etc. are provided for each color.

[0032] When a light beam is incident on the synchronization sensor 218, the synchronization sensor 218 outputs a synchronization detection signal XDETP. Then, the synchronization detection signal XDETP is output to a lighting control device 222 for synchronization detection, a writing start position control device 224, and a pixel clock generation device 225.

[0033] The pixel clock generation device 225 generates a pixel clock signal PCLK synchronized with the synchronization detection signal XDETP. After that, the pixel clock generation device 225 sends the pixel clock signal PCLK to the lighting control device 222 for synchronization detection and the writing start position control device 224.

[0034] The lighting control device 222 for synchronization detection turns on the LD forced lighting signal BD in order to detect the synchronization detection signal XDETP. Therefore, when the LD forced lighting signal BD is turned on, the LD control board 211 emits a light beam, that is, turns on the LD.

[0035] After detecting the synchronization detection signal XDETP, the writing start position control device 224 generates the LD forced lighting signal BD using the synchronization detection signal XDETP and the pixel clock signal PCLK. The LD forced lighting signal BD is generated at the timing when the synchronization detection signal XDETP can be detected, turns on the LD to such an extent that flare light does not occur, and turns off when the synchronization detection signal XDETP is detected.

[0036] When the writing start position control device 224 generates the LD forced lighting signal BD, it sends it to the LD control device 223.

[0037] The writing start position control device 224 generates an optical power control timing signal APC. Also, the optical power control timing signal APC is generated using the synchronization detection signal XDETP and the pixel clock signal PCLK. After generation, the writing start position control device 224 sends the optical power control timing signal APC to the LD control device 223.

[0038] The optical power control timing signal APC is used outside the writing area and the like. And the optical power control timing signal APC is used to control the optical power.

[0039] The LD control device 223 turns on the LD based on the image data. The signal indicating the image data is a signal synchronized with the LD forced turn-on signal BD, the light amount control timing signal APC, and the pixel clock signal PCLK. When the LD is turned on, the light beam is polarized by the polygon mirror 213. Then, the light beam reflected by the polygon mirror 213 scans over the photoreceptor drum 40 through the fθ lens 214.

[0040] The polygon motor control device 221 controls the polygon mirror 213 based on the control signal sent by the printer control device 1. For example, the polygon motor control device 221 controls the polygon mirror 213 to rotate at a predetermined rotational speed.

[0041] The writing start position control device 224 generates the main scanning control signal XLGATE and the sub-scanning control signal XFGATE.

[0042] The main scanning control signal XLGATE and the sub-scanning control signal XFGATE determine the timing of image writing and the width of the image. Also, the main scanning control signal XLGATE and the sub-scanning control signal XFGATE are generated based on the synchronous detection signal XDETP, the pixel clock signal PCLK, and the control signal sent by the printer control device 1.

[0043] The first sensor SN1 and the second sensor SN2 detect the pattern used to calculate the image misalignment. Specifically, when the first sensor SN1 and the second sensor SN2 detect the pattern, they send the information obtained by the first sensor SN1 and the second sensor SN2 to the printer control device 1. Then, the printer control device 1 calculates the misalignment amount, etc. based on the information. Next, the printer control device 1 generates correction data based on the calculation result of the misalignment amount. For example, the correction data is used for the settings of the writing start position control device 224, the pixel clock generation device 225, etc. Also, the correction data is stored in the storage device 229.

[0044] The memory device 229 provides correction data and the like to the printer control device 1 during image formation.

[0045] FIG. 4 is a diagram showing a configuration example of an electric circuit. For example, the image forming apparatus 100 is configured by connecting the devices as shown in the figure.

[0046] The control device 200 controls each device, acquires data from sensors, and performs processes such as arithmetic operations. For example, the control device 200 is a device including a Central Processing Unit (CPU), a Random Access Memory (RAM), and a Read Only Memory (ROM).

[0047] Connected to the control device 200 are an intermediate transfer belt motor 201, a secondary transfer belt motor 202, a motor driver 203, an operation display device 204, a black (K) image forming motor 205, and yellow (Y), magenta (M), and cyan (C) image forming motors 206.

[0048] For example, based on the control of the control device 200, the rotation speed of the secondary transfer belt motor 202 is controlled. Thus, when controlling the secondary transfer belt motor 202, the conveyance speed of the secondary transfer belt is changed and the magnification of the image can be changed.

[0049] The intermediate transfer belt motor 201 rotates a roller that drives the intermediate transfer belt 10. Therefore, when the intermediate transfer belt motor 201 is driven, the intermediate transfer belt 10 moves.

[0050] The secondary transfer belt motor 202 rotates a roller that drives the secondary transfer belt 23. Therefore, when the secondary transfer belt motor 202 is driven, the secondary transfer belt 23 moves.

[0051] The control device 200 controls the stepping motor 73 via the motor driver 203. For example, the control device 200 reversely rotates the stepping motor 73 by a predetermined amount in the nip state during secondary transfer. With such control, when the stepping motor 73 reversely rotates, the movable roller descends, and the secondary transfer belt 23 separates from the intermediate transfer belt 10.

[0052] On the other hand, the control device 200 rotates the stepping motor 73 forward in the nip state during secondary transfer. With such control, when the stepping motor 73 rotates forward, the movable roller ascends, and the secondary transfer belt 23 comes into contact with the intermediate transfer belt 10.

[0053] The operation display device 204 is installed outside the image forming apparatus 100. For example, the operation display device 204 includes a touch panel or keys, etc. And the operations of the user are received by the operation display device 204. Therefore, the operation display device 204 acquires information and makes settings according to the operations of the user.

[0054] Note that the information acquired by the operation display device 204 is sent to the control device 200. Also, the operation display device 204 displays the processing results, etc. to the user.

[0055] The K image forming motor 205 and the YMC image forming motor 206 are the drive sources of the image forming units of each color.

[0056] For example, when the secondary transfer belt 23 or the intermediate transfer belt 10 is replaced, etc., work records, etc. are input. When such work records are input, the image forming apparatus 100 supplies lubricant, etc. according to the type of the replaced belt.

[0057] Note that the configuration of the apparatus is not limited to the illustrated configuration, and there may be other apparatuses.

[0058] [Pattern, and Detection Example of Pattern] FIG. 5 is a diagram showing a pattern and an example of detecting the pattern. For example, the pattern has a shape as shown in the drawing and is formed on the secondary transfer belt 23 during a period when image formation is not performed. Hereinafter, an example of the pattern having the shape as shown in the drawing, the number of sensors, and the sensor arrangement will be described. However, the pattern, the number of sensors, the sensor arrangement, etc. may be other than those shown in the drawing.

[0059] Specifically, the pattern includes horizontal lines such as a first black horizontal line K1, a first cyan horizontal line C1, a first magenta horizontal line M1, a first yellow horizontal line Y1, a second black horizontal line K2, a second cyan horizontal line C2, a second magenta horizontal line M2, and a second yellow horizontal line Y2.

[0060] Furthermore, the pattern includes slanted lines such as a third black slanted line K3, a third cyan slanted line C3, a third magenta slanted line M3, a third yellow slanted line Y3, a fourth black slanted line K4, a fourth cyan slanted line C4, a fourth magenta slanted line M4, and a fourth yellow slanted line Y4. For example, the pattern is a combination of the horizontal lines and the slanted lines formed on the secondary transfer belt 23.

[0061] When the secondary transfer belt 23 moves (in the drawing, it moves upward), the first sensor SN1 and the second sensor SN2 detect the horizontal lines or the slanted lines. Then, the detection results by the first sensor SN1 and the second sensor SN2 are sent to the printer control device 1.

[0062] For example, the deviation amount is calculated in units of time based on a predetermined color. Hereinafter, an example based on black will be described. Specifically, when the position of the image or the magnification of the image deviates in the main scanning direction, the timing at which the slanted lines are detected changes. Also, when the position of the image deviates in the sub-scanning direction, the timing at which the horizontal lines are detected changes.

[0063] In the example of the first sensor SN1, for the main scanning direction, first, the time from when the first black horizontal line K1 is detected until the third black slanted line K3 is detected is used as a reference. For example, for cyan, the time from when the first cyan horizontal line C1 is detected until the third cyan slanted line C3 is detected is measured.

[0064] Then, a reference time, i.e., the black time, and the cyan time are compared, and a deviation amount for cyan is calculated.

[0065] Similarly, in the example of the second sensor SN2, for the main scanning direction, first, the time from when the second black horizontal line K2 is detected until the fourth black diagonal line K4 is detected is used as a reference. For example, for cyan, the time from when the second cyan horizontal line C2 is detected until the fourth cyan diagonal line C4 is detected is measured.

[0066] And, similar to the example of the first sensor SN1, the reference time, i.e., the black time, and the cyan time are compared, and a deviation amount for cyan is calculated.

[0067] In this case, the magnification error for cyan is calculated as a deviation amount from the difference between the deviation amount based on the second cyan horizontal line C2 and the fourth cyan diagonal line C4 and the deviation amount based on the first cyan horizontal line C1 and the third cyan diagonal line C3.

[0068] The image forming apparatus 100 corrects the deviation amount by converting the calculated deviation amount into a pixel clock. The deviation amount in the main scanning direction is corrected, for example, by adjusting the main scanning control signal XLGATE, i.e., the writing timing.

[0069] Regarding the sub-scanning direction, the time in an ideal state is referred to as "Tc", the time from the first black horizontal line K1 to the first cyan horizontal line C1 is referred to as "TKC1", and the time from the second black horizontal line K2 to the second cyan horizontal line C2 is referred to as "TKC2" for explanation.

[0070] The deviation amount in the sub-scanning direction is calculated, for example, as shown in the following equation (1).

[0071] Deviation amount in the sub-scanning direction = {(TKC2 + TKC1) / 2} - Tc (1) The deviation amount calculated by the above formula (1) is the deviation amount of cyan with respect to black. For example, the deviation amount in the sub-scanning direction is corrected by adjusting the sub-scanning control signal XFGATE. Note that other colors are corrected in the same way.

[0072] Note that the pattern is not limited to the shape formed at two locations as shown in the figure. Also, for example, a plurality of sets as shown in the figure may be arranged. And the deviation amount may be calculated by performing statistical processing such as averaging the detection results or calculation results of a plurality of patterns.

[0073] <Overall Processing Example> For example, the magnification of the pattern is performed in the process as shown in FIG. 6 below. That is, hereinafter, an example in which the image forming apparatus 100 performs correction in the process shown in FIG. 7 after performing the process shown in FIG. 6 is given.

[0074] FIG. 6 is a diagram showing an example of control processing in image formation. For example, when a user inputs an operation of pressing a start key on the operation panel, the image forming apparatus 100 starts the process shown in FIG. 6.

[0075] In step S0601, the image forming apparatus 100 starts the rotation of the polygon motor. Note that the number of rotations for rotating the polygon motor is instructed by, for example, the printer control device 1.

[0076] In step S0602, the image forming apparatus 100 sets the magnification of the image.

[0077] In step S0603, the image forming apparatus 100 sets correction data.

[0078] By steps S0602 and S0603, the image forming apparatus 100 determines the write start position and the like in the main scanning direction and the sub-scanning direction. Then, the image forming apparatus 100 performs operations such as lighting of the LD for outputting the synchronous detection signal XDETP and APC operation for lighting the LD with a predetermined light amount. Note that the image forming apparatus 100 may perform other settings regarding image formation.

[0079] In step S0604, the image forming apparatus 100 starts lighting the LD.

[0080] In step S0605, the image forming apparatus 100 performs image formation.

[0081] In step S0606, the image forming apparatus 100 determines whether there is a next image. If there is a next image (YES in step S0606), the image forming apparatus 100 proceeds to step S0605. On the other hand, if there is no next image (NO in step S0606), the image forming apparatus 100 proceeds to step S0607.

[0082] That is, when there is a target image, the image forming apparatus 100 performs image formation based on the settings. And if there is a target image, the image forming apparatus 100 repeatedly performs image formation. On the other hand, when there is no target image, the image forming apparatus 100 performs processing to end the image formation as follows.

[0083] In step S0607, the image forming apparatus 100 turns off the LD.

[0084] In step S0608, the image forming apparatus 100 stops the rotation of the polygon motor.

[0085] FIG. 7 is a diagram showing an example of control processing for performing correction. For example, when the image forming apparatus 100 forms a preset number of images or determines that there is a temperature change of a certain degree or more by measuring the temperature, the following correction is performed.

[0086] In step S0701, the image forming apparatus 100 sets correction data.

[0087] In step S0702, the image forming apparatus 100 forms a pattern.

[0088] In step S0703, the image forming apparatus 100 detects the pattern.

[0089] In step S0704, the image forming apparatus 100 calculates the deviation amount.

[0090] For example, as shown in FIG. 5, the image forming apparatus 100 forms and detects a pattern. Then, based on the detection result, the image forming apparatus 100 calculates the deviation amount.

[0091] In step S0705, the image forming apparatus 100 may determine whether to perform correction. If it is determined to perform correction (YES in step S0705), the image forming apparatus 100 proceeds to step S0706. On the other hand, if it is determined not to perform correction (NO in step S0705), the image forming apparatus 100 ends the process without performing correction. That is, when correction is not performed, the correction data is maintained.

[0092] For example, if the deviation amount is equal to or greater than "1 / 2" of the correction resolution, the image forming apparatus 100 determines to perform correction. That is, the image forming apparatus 100 may perform correction when the deviation amount is equal to or greater than a certain value and the deviation amount is a large value. The value serving as a criterion for determining whether to perform correction, etc. is set in advance, for example.

[0093] In step S0706, the image forming apparatus 100 generates correction data.

[0094] In step S0707, the image forming apparatus 100 stores the correction data.

[0095] In step S0708, the image forming apparatus 100 sets the correction data.

[0096] As described above, the image forming apparatus 100 calculates the deviation amount based on the pattern. Based on the deviation amount calculated in this way, new correction data is generated. Then, the image forming apparatus 100 updates the correction data set in step S0701, etc. with the newly generated correction data. Thereafter, based on the updated correction data, the image forming apparatus 100 performs correction.

[0097] In step S0709, the image forming apparatus 100 performs correction so as to reduce the deviation amount.

[0098] Thereafter, the image forming apparatus 100 forms an image in the corrected state.

[0099] The correction data is, for example, data indicating the set value of the pixel clock frequency for determining the magnification, and the settings of the main scanning control signal XLGATE, the sub-scanning control signal XFGATE, etc. in the main scanning direction.

[0100] Note that the order of processing is not limited to the order shown above. For example, the processing may be performed in parallel or in an order different from that shown in the figure.

[0101] [Example of magnification change] FIG. 8 is a diagram showing an example when there is no magnification change. Hereinafter, an example will be described in which the first sensor SN1 uses the first black horizontal line K1, the first cyan horizontal line C1, the first magenta horizontal line M1, and the first yellow horizontal line Y1 as patterns as shown in the figure.

[0102] Also, the following description will be given by taking the case of FIG. 8 as a reference for the interval between the horizontal lines in the Y direction, that is, the case where there is no magnification change.

[0103] FIG. 9 is a diagram showing an example of an enlarging magnification. Compared with the setting shown in FIG. 8, it is different in that the interval between the horizontal lines is wide.

[0104] FIG. 10 is a diagram showing an example of a reducing magnification. Compared with the setting shown in FIG. 8, it is different in that the interval between the horizontal lines is narrow.

[0105] For example, the magnification is changed according to the variation of mechanical parts, the presence or absence of paper, or the type of paper thickness, etc. Also, the magnification may be set arbitrarily.

[0106] The magnification is set, for example, by changing the rotation speed of the polygon motor, the image data, or the conveyance speed of the secondary transfer belt.

[0107] Note that the conveyance speed of the secondary transfer belt may be changed in consideration of its thickness. By changing the conveyance speed in consideration of the thickness, the image magnification on the recording medium can be adjusted. However, in that case, the pattern on the secondary transfer belt when there is no recording medium is affected by the magnification. Therefore, even when the magnification finally changes due to the thickness of the recording medium or the like, the image forming apparatus 100 can accurately correct the deviation amount when performing correction in consideration of the magnification.

[0108] Hereinafter, without changing the magnification, that is, at the intervals shown in FIG. 8, the interval between the first black horizontal line K1 and the first cyan horizontal line C1 is referred to as "Tc" (the unit is time). Similarly, at the intervals shown in FIG. 8, the interval between the first black horizontal line K1 and the first magenta horizontal line M1 is referred to as "Tm". Further, at the intervals shown in FIG. 8, the interval between the first black horizontal line K1 and the first yellow horizontal line Y1 is referred to as "Ty". That is, "Tc", "Tm", and "Ty" are ideal times with no deviation amount.

[0109] On the other hand, as a result of the detection by the first sensor SN1, assume that the time from the first black horizontal line K1 to the first cyan horizontal line C1 is "TKC1".

[0110] In this case, the deviation amount is calculated as, for example, "TKC1 - Tc". To correct such a deviation amount in the sub-scanning direction, the image forming apparatus 100 changes the timing of the sub-scanning control signal XFGATE. Using correction data indicating such correction content, color misregistration can be corrected.

[0111] The magnification can be grasped, for example, from a previous setting. Hereinafter, the variable amount due to enlargement or reduction is set as "x"%. When such a magnification is set, the image forming apparatus 100 calculates the deviation amount as, for example, "TKC1 - Tc×(100 + x) / 100" in the case of black.

[0112] In this way, when correcting in consideration of the magnification, the deviation amount can be calculated as follows.

[0113] FIG. 11 is a diagram showing an example of calculating the deviation amount when there is no magnification change.

[0114] FIG. 12 is a diagram showing an example of calculating the deviation amount when there is a magnification change.

[0115] "Color plate" indicates the type of color. "a)" is the ideal position, that is, the reference position. "b)" is the detected position. "c)" is the result of calculating the deviation amount without considering the change in magnification.

[0116] As shown in FIG. 11, when there is no magnification change, the deviation amount, that is, "c)", is calculated as the difference between "a)" and "b)".

[0117] For example, taking cyan (C) in FIG. 12 as an example. "1040.4" shown in "b)" is the result calculated as "1020×(100 + 2) / 100" based on " TKC1 = TKC1 (equal magnification) × magnification ".

[0118] "-31" shown in "c)" is the result calculated as " TKC1 - Tc " based on " 969-1000 ".

[0119] "19" shown in "d)" is the result calculated as "{1020×(100 - 5) / 100}-{1000×(100 - 5) / 100}".

[0120] "20" shown in "e)" is the result calculated as "19×{100 / (100 - 5)}".

[0121] "d)" indicates the deviation amount in the zoomed state. On the other hand, "e)" indicates the deviation amount in the non-zoomed state. For example, when the magnification is "-5%", and the next image has no magnification change, using the result of "d)", the image forming apparatus 100 can accurately correct the deviation amount. In addition, even when the deviation amount is calculated in the state where the magnification is "-5%", and the next image has a magnification of "+2%", the image forming apparatus 100 can accurately correct the deviation amount.

[0122] On the other hand, if the magnification is set but not taken into account, the image forming apparatus 100 may erroneously recognize that there is a deviation. Therefore, as described above, when calculating while taking the magnification into account, the image forming apparatus 100 can reduce the erroneous recognition of the deviation amount.

[0123] [Second Embodiment] FIG. 13 is a diagram showing an example of a pattern in the second embodiment. In the second embodiment, the image forming apparatus 100 uses a pattern as shown in the figure, for example.

[0124] In the second embodiment, the image forming apparatus 100 is different in that it uses patterns with different magnifications. Specifically, as shown in the figure, among a plurality of sets, the 21st pattern PTN21 which is an example of the first pattern is a pattern formed with the normal magnification, that is, the setting without magnification change.

[0125] On the other hand, among a plurality of sets, the 22nd pattern PTN22 which is an example of the second pattern is a pattern formed with an enlarged magnification setting.

[0126] Therefore, assuming that the magnification is based on the first magnification and the second magnification is larger than the first magnification.

[0127] Note that the combination and order of magnifications are not limited to the example shown in the figure.

[0128] In the second embodiment, the image forming apparatus 100 calculates the deviation amount for each pattern using the magnification at which each pattern is formed.

[0129] When the deviation amount is calculated as described above, even when the magnification is changed midway, the image forming apparatus 100 can accurately calculate the deviation amount and perform accurate correction.

[0130] Also, when there are patterns with multiple magnifications, the image forming apparatus 100 may select the pattern with a larger number and calculate the deviation amount. In the illustrated example, the first pattern is two sets. On the other hand, the second pattern is three sets. On the other hand, the two sets of patterns are not used for calculating the deviation amount using detection results or the like.

[0131] In such a case, the image forming apparatus 100 may select the second pattern with a larger number and calculate the deviation amount. By doing so, even when patterns with different magnifications are mixed, the image forming apparatus 100 can accurately calculate the deviation amount.

[0132] [Third Embodiment] FIG. 14 is a diagram showing an example of a pattern in the third embodiment. When compared with FIG. 13, the point where the magnification changes is different. Specifically, the 31st pattern PTN31 is a pattern formed with the normal magnification, that is, the setting without magnification change. On the other hand, the 32nd pattern PTN32 is a pattern formed with an enlarged magnification setting.

[0133] In the illustrated example, there are four horizontal lines constituting the pattern. Among these horizontal lines, the upper two lines in the figure (black and cyan) and the lower two lines (magenta and yellow) have different magnifications.

[0134] A pattern in which the magnification is changed during formation may be excluded from the calculation of the deviation amount. By doing so, even when a pattern in which the magnification is changed midway is mixed, the image forming apparatus 100 can accurately calculate the deviation amount.

[0135] [Functional Configuration Example] FIG. 15 is a diagram showing a functional configuration example. For example, the image forming apparatus 100 includes an image forming unit FN1, a correction unit FN2, a change unit FN3, and a calculation unit FN4.

[0136] The image forming unit FN1 performs an image forming procedure for forming an image. For example, the image forming unit FN1 is realized by an image forming device 20 or the like.

[0137] The correction unit FN2 performs a correction procedure for correcting the deviation amount based on the pattern to be formed. For example, the correction unit FN2 is implemented by the printer control device 1 or the like.

[0138] The changing unit FN3 performs a changing procedure for changing the magnification of the pattern. For example, the changing unit FN3 is implemented by the printer control device 1 or the like.

[0139] The calculation unit FN4 performs a calculation procedure for calculating the deviation amount based on the magnification. For example, the calculation unit FN4 is implemented by the printer control device 1 or the like.

[0140] The pattern may change based on the magnification of the image. For example, there may be a case where image formation is performed while the magnification fluctuates. Also, when the settings vary by page, the magnification may also be different.

[0141] Therefore, if the deviation amount is calculated without considering the magnification, there may be an incorrect recognition such as a deviation occurring. If correction is performed with such an incorrectly recognized deviation amount, the deviation may instead increase. Thus, when calculating the deviation amount considering the magnification, the image forming apparatus 100 can accurately calculate the deviation amount. Using such a deviation amount, the image forming apparatus 100 can accurately perform correction even when the magnification of the image changes.

[0142] [Other Embodiments] The image forming method described above may be implemented, for example, by a program such as firmware for some of the processes. That is, the image forming method is a method executed by a computer by causing an arithmetic unit, a storage unit, an input unit, an output unit, and a control unit to operate in cooperation based on a program. Also, the program may be written and distributed in a storage device or a storage medium, or distributed through an electric communication line or the like.

[0143] Each of the devices described above does not have to be a single device. That is, each device may be an image forming system or the like configured by a plurality of devices.

[0144] The image forming apparatus 100 may be, for example, a commercial printing machine (such as a large electrophotographic printer or an inkjet printer, etc.).

[0145] The recording medium is, for example, paper (also referred to as "plain paper", etc.). However, the recording medium may be coated paper, label paper, etc. other than paper, overhead projector sheets, films, or flexible thin plates, etc. Further, the recording medium may be roll paper, etc.

[0146] Specifically, the recording medium is a recording medium such as paper, film, or cloth, etc.

[0147] Thus, the material of the recording medium is paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, or a combination thereof, etc.

[0148] Note that the present invention is not limited to each of the embodiments exemplified above, and various modifications are possible without departing from the technical gist, and all of the technical matters included in the technical idea described in the claims are the subject of the present invention.

[0149] The above embodiments show preferred examples, but those skilled in the art can realize various modified examples from the disclosed content. Such modified examples are also included in the technical scope described in the claims.

Explanation of Reference Numerals

[0150] 100: Image forming apparatus SN1: First sensor SN2: Second sensor FN1: Image forming unit FN2: Correction unit FN3: Modifying unit FN4: Calculation unit PTN21: 21st pattern PTN22: 22nd pattern PTN31: 31st pattern PTN32: 32nd pattern C1: First cyan horizontal line C2: Second cyan horizontal line C3: Third cyan diagonal line C4: Fourth cyan diagonal line K1: First black horizontal line K2: Second black horizontal line K3: Third black diagonal line K4: Fourth black diagonal line M1: First magenta horizontal line M2: Second magenta horizontal line M3: Third magenta diagonal line M4: Fourth magenta diagonal line Y1: First yellow horizontal line Y2: Second yellow horizontal line Y3: Third yellow diagonal line Y4: Fourth yellow diagonal line

Prior Art Documents

Patent Documents

[0151]

Patent Document 1

Claims

1. A plurality of image forming units that perform image formation based on a set magnification, a detection unit that detects a plurality of patterns formed by the plurality of image forming units, a calculation unit that calculates a deviation amount between the plurality of patterns based on a detection result by the detection unit, and a correction unit that corrects an image formation timing at which the plurality of image forming units form an image based on the deviation amount. The image forming apparatus is provided with: The calculation unit When there is no change in the set magnification, the deviation amount is calculated as the difference between the detection time between the plurality of patterns detected by the detection unit when there is no change in the set magnification and the ideal time when there is no deviation amount between the plurality of patterns detected by the detection unit. When there is a change in the set magnification, the ideal detection time is corrected by multiplying the changed magnification due to the magnification change by the ideal time, and the difference between the detection time between the plurality of patterns detected by the detection unit and the corrected ideal time is calculated as the deviation amount. Image forming apparatus.

2. The image forming apparatus further includes a changing unit that changes the conveyance speed of the secondary transfer belt used by the image forming unit to change the magnification. The image forming apparatus according to claim 1.

3. The calculation unit uses a plurality of the patterns with different magnifications, and calculates the deviation amount by changing the magnification for each of the patterns. The image forming apparatus according to claim 1 or 2.

4. In the case of using a plurality of the patterns with different magnifications, the image forming unit forms a first pattern formed at a first magnification among the patterns, and a second pattern formed at a second magnification among the patterns, The calculation unit selects the pattern with a larger number among the first pattern and the second pattern and calculates the deviation amount. The image forming apparatus according to any one of claims 1 to 3.

5. A plurality of image forming units that perform image formation based on a set magnification, a detection unit that detects a plurality of patterns formed by the plurality of image forming units, a calculation unit that calculates a deviation amount between the plurality of patterns based on a detection result by the detection unit, and a correction unit that corrects an image formation timing at which the plurality of image forming units form an image based on the deviation amount. The image forming apparatus is provided with: The calculation unit corrects and calculates the deviation amount based on the set magnification, and calculates the deviation amount excluding a pattern whose magnification is changed during formation. Image forming apparatus.

6. A plurality of image forming units that perform image formation based on a set magnification, a detection unit that detects a plurality of patterns formed by the plurality of image forming units, a calculation unit that calculates a deviation amount between the plurality of patterns based on a detection result by the detection unit, and a correction unit that corrects an image formation timing at which the plurality of image forming units form an image based on the deviation amount and includes: The calculation unit: When there is no change in the set magnification, the deviation amount is calculated as the difference between the detection time between the plurality of patterns detected by the detection unit when there is no change in the set magnification and the ideal time when there is no deviation amount between the plurality of patterns detected by the detection unit, When there is a change in the set magnification, the ideal detection time is corrected by multiplying the changed magnification due to the magnification change by the ideal time, and the difference between the detection time between the plurality of patterns detected by the detection unit and the corrected time of the ideal time is calculated as the deviation amount An image forming system.

7. An image forming method performed by an image forming apparatus, including an image formation procedure for performing a plurality of image formations based on a set magnification, a detection procedure for detecting a plurality of patterns formed by the plurality of image formations, a calculation procedure for calculating a deviation amount between the plurality of patterns based on a detection result by the detection procedure, and a correction procedure for correcting an image formation timing at which an image is formed in the plurality of image formations based on the deviation amount and including: In the calculation procedure: When there is no change in the set magnification, the deviation amount is calculated as the difference between the detection time between the plurality of patterns detected by the detection procedure when there is no change in the set magnification and the ideal time when there is no deviation amount between the plurality of patterns detected by the detection procedure, When there is a change in the set magnification, the ideal detection time is corrected by multiplying the changed magnification due to the magnification change by the ideal time, and the difference between the detection time between the plurality of patterns detected by the detection procedure and the corrected time of the ideal time is calculated as the deviation amount An image forming method.

Images