JP2006267564A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily adjust a misalignment occurring even in a single job. <P>SOLUTION: The image forming apparatus includes; an image forming means 3 for forming an image on a paper sheet; a correction control means 21 for performing the correction related to the image formation in the case of forming the image by the image forming means 3; state detecting means 22 to 25 for detecting the state in the apparatus; an information storage means 26 for storing information on a relation between the correction amount related to the image formation and the state of the apparatus; and a correction amount predicting means 27 for predicting the correction amount in the case of performing the correction by the correction control means 21 based on the detection results by the state detecting means 22 to 25 and the information stored by the information storage means 26, and then, giving instructions to the correction control means 21. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus that forms and outputs an image on paper using an electrophotographic system, such as a copying machine or a printer.

  In general, in an image forming apparatus using an electrophotographic method, an electrostatic latent image corresponding to an image signal is formed on a photoconductor, and a toner image obtained by developing the image is transferred onto a sheet, and then on the sheet. An image is formed on a sheet by fixing the toner image. For example, an image forming unit corresponding to the formation of a color image includes four image forming units arranged in parallel corresponding to each color component of yellow (Y), magenta (M), cyan (C), and black (K). The toner images of each color component of YMCK, which are sequentially formed by each of these image forming units, are transferred (primary transfer) onto an intermediate transfer belt as an image carrier, and then collectively transferred from the intermediate transfer belt onto a sheet ( Secondary transfer), and the toner image formed on the paper is fixed.

  In an image forming apparatus using such an electrophotographic system, usage conditions of an apparatus component for performing an image forming operation such as a paper conveyance system or an image forming unit (for example, an installation position of the apparatus component, a driving timing thereof) Depending on the environmental conditions (for example, temperature and humidity) at the time of image forming operation, the alignment of the image formed on the paper (for example, the vertical magnification, horizontal magnification, parallelism, squareness of the image) , Lead registration, side registration, side skew) may occur.

  Therefore, conventionally, in an image forming apparatus, an image formed by the image forming apparatus is read, and based on the read result, the use conditions of the apparatus constituent elements used for image formation are adjusted, whereby the image is formed. Some image alignment devices can be adjusted during actual use of the forming apparatus, preventing the occurrence of positional deviation and shape change of the formed image, and obtaining a high-quality and high-quality image (for example, Patent Documents). 1). The alignment adjustment of the formed image is performed at the time of shipment of the image forming apparatus from the factory, and is generally performed as necessary even when installed in the environment used by the user. Furthermore, even after the installation of the apparatus, it has been proposed to make adjustments at times such as when the paper size is changed, when the paper type is changed, or when the temperature changes rapidly, such as early morning or noon (for example, Patent Document 1). Such adjustment after the installation of the apparatus is intended to cope with a difference in environmental conditions when performing an image forming operation, such as a difference in sheet shrinkage due to the moisture content of the sheet and a change in dimension of the adjusting member.

JP 2004-271746 A

  Incidentally, some image forming apparatuses support processing of jobs with a large number of printed sheets (for example, 1000 sheets or more) in order to meet the demand for realizing high productivity. However, in recent verification, it is known that a slight misalignment occurs in a job with a large number of prints, and a positional deviation or a shape change occurs in a formed image. Specifically, there may be a difference between the average value of image positions and the like for several sheets immediately after the start of job processing and the average value of several image positions and the like immediately before the end of the job.

  Such misalignment that can occur in a single job cannot be dealt with by the above-described alignment adjustment at the time of factory shipment, installation of the apparatus, or a specific time zone. Further, in the above-described conventional image forming apparatus, it is necessary to read an image formed by the image forming apparatus and make the processing based on the read result when performing alignment adjustment. I can't say that.

  Therefore, the present invention provides an image forming apparatus capable of easily adjusting misalignment that may occur even within a single job, thereby realizing high-production, high-quality, and high-quality image formation. The purpose is to provide.

  The present invention is an image forming apparatus devised to achieve the above object, and an image forming unit that forms an image on a sheet, and a correction related to the image formation when the image forming unit forms an image. Correction adjustment means for performing, state detection means for detecting the state in the apparatus including the image forming means, and information storage means for storing information on the relationship between the amount of correction relating to the image formation and the state in the apparatus And a correction amount prediction unit that predicts a correction amount when the correction adjustment unit performs correction based on a detection result of the state detection unit and information stored in the information storage unit, and instructs the correction adjustment unit. Are provided.

  In the image forming apparatus configured as described above, the correction adjustment unit performs correction related to image formation. Here, “correction relating to image formation” refers to correction of at least one of vertical magnification, horizontal magnification, parallelism, squareness, lead registration, side registration, and side skew of an image formed by the image forming unit, for example. This corresponds to the alignment adjustment of the formed image. However, the correction by the correction adjustment unit is performed based on an instruction from the correction amount prediction unit. The correction amount at that time is predicted by the correction amount prediction unit based on the detection result of the state in the apparatus by the state detection unit and the information stored in the information storage unit. Here, the “state in the apparatus” refers to, for example, temperature and humidity in the image forming apparatus, and corresponds to an environmental condition when performing a so-called image forming operation. Therefore, the correction adjustment means adjusts the alignment of the formed image according to the environmental conditions when performing the image forming operation.

As described above, in the image forming apparatus according to the present invention, the alignment of the formed image is adjusted according to the environmental conditions when performing the image forming operation. Therefore, the formed image is read for the alignment adjustment. This is not necessary, and the alignment can be easily adjusted. In addition, if the environmental conditions change, the alignment adjustment can be performed accordingly. Therefore, even if there is an alignment shift that may occur within a single job, the adjustment can be performed.
Therefore, according to the image forming apparatus of the present invention, a high-quality and high-quality formed image can be obtained even with a large number of jobs, so that high-production, high-quality and high-quality image formation is realized. be able to.

  Hereinafter, an image forming apparatus according to the present invention will be described with reference to the drawings.

  First, a schematic configuration of the entire image forming apparatus will be described. FIG. 1 is an explanatory diagram showing a schematic configuration example of an image forming apparatus according to the present invention. As shown in the figure, an image forming apparatus 1 described here is of a so-called tandem type and intermediate transfer type, and includes an image reading unit 2 that reads an image of a document, and an image forming unit that forms an image on a sheet. 3, a sheet supply unit 4 that supplies sheets to the image forming unit 3, a sheet discharge unit 5 that discharges an image-formed sheet, and a control unit 6 that controls operations of these units. Is done. Note that the details of the image reading unit 2, the paper supply unit 4, and the paper discharge unit 5 are configured using a known technique, and thus the description thereof is omitted here.

  The image forming unit 3 includes a plurality of image forming units 10 (10Y, 10M, 10C, and 10K) on which toner images of each color component are formed by an electrophotographic method, and each color component toner formed by each image forming unit 10. An intermediate transfer belt 11 that sequentially transfers (primary transfer) and holds an image, and an overlapping toner image transferred on the intermediate transfer belt 11 is collectively transferred (secondary transfer) to a sheet of recording material (transfer material). The image forming apparatus includes a next transfer unit 12 and a fixing unit 13 that fixes the second transferred image on the sheet.

In the image forming apparatus 1 configured as described above, when an image of a document is read by the image reading unit 2, a toner image is formed by the image forming unit 3 based on an image signal obtained thereby. In the image forming unit 3, toner images of each color of YMCK are formed by the four image forming units 10. The toner images of the respective colors formed in this way are sequentially transferred onto the intermediate transfer belt 11. As a result, a multicolor (full color) toner image is formed on the intermediate transfer belt 11 by superimposing four color toner images. The toner image formed on the intermediate transfer belt 11 is sent to the secondary transfer unit 12 while being carried on the intermediate transfer belt 11.
On the other hand, the tray image selected by the user using an operation panel (not shown) or the tray paper selected by the automatic selection function causes the toner image on the intermediate transfer belt 11 to reach the secondary transfer unit 12. The paper is fed from the paper supply unit 4 to the image forming unit 3 in accordance with the timing of the image.
In the secondary transfer unit 12, the toner image (full color image) carried on the intermediate transfer belt 11 is batch-transferred (secondarily transferred) onto the paper. Thereafter, the sheet on which the toner image has been transferred is sent to the fixing unit 13 and is heated and pressed and fixed, and then discharged to the sheet discharge unit 5.
In addition, when image formation is performed on both sides of the paper, the paper on which the image is formed on one side is turned upside down and the timing is adjusted, and then sent to the secondary transfer unit 12 to the other side. An image is formed.
Here, a mode in which the image reading unit 2 is mounted on the main body is taken as an example, but a mode in which a so-called printer and a single scanner are connected may be used. Further, it goes without saying that the image forming apparatus 1 is also applicable to only a monochrome monochrome function.

  By the way, the image forming apparatus 1 having the above-described configuration has a function of adjusting the alignment of an image formed on a sheet when the image is formed on the sheet.

  Here, the alignment elements to be adjusted will be described. FIG. 2 is an explanatory view showing a specific example of the alignment element. As shown in the figure, examples of alignment elements to be adjusted include, for example, image magnification (vertical magnification or horizontal magnification), rotation (parallelism), skew (perpendicularity), skew, misregistration (lead registration or At least one of the side registration), left-right difference due to in-out expansion / contraction difference, and bow (bow deformation). The vertical magnification is a scale indicating the expansion / contraction of the image in the paper transport direction. The lateral magnification is a scale indicating the expansion and contraction of an image in a direction orthogonal to the paper conveyance direction. The degree of parallelism is a scale indicating whether an image can be drawn in parallel with the paper conveyance direction. The squareness is a scale indicating whether or not an image can be drawn at right angles to a direction orthogonal to the paper conveyance direction. The skew is a measure indicating whether or not the sheet is inclined with respect to the sheet conveyance direction when an image is formed on the sheet. The lead registration is a scale indicating whether or not the position in the sheet conveyance direction is shifted to one end side (front side or rear side as viewed from the sheet conveyance direction) when an image is formed on the sheet. The side register is a scale indicating whether or not the position in the direction orthogonal to the paper transport direction is shifted to one end side (right side or left side when viewed from the paper transport direction) when an image is formed on the paper. The left-right difference due to the in-out expansion / contraction difference is a scale indicating a difference in expansion / contraction of the image on the right paper end side and the left paper end side when viewed from the sheet conveyance direction. The arcuate deformation is a scale indicating whether or not the image is curved in a direction orthogonal to the paper conveyance direction.

  These alignment elements can be adjusted as described below. 3-7 is explanatory drawing which shows the specific example of alignment adjustment. When image formation is performed on both sides of a sheet, the following adjustments can be made independently on each side.

  The adjustment of the vertical magnification is performed by adjusting the speed of a belt drive motor that drives the intermediate transfer belt 11. Further, as shown in FIG. 3, the lateral magnification is adjusted by changing the laser writing frequency of the laser exposure device in each image forming unit 10. That is, it can be considered that the vertical magnification adjustment is performed using the speed of the belt drive motor as an adjustment parameter, and the horizontal magnification adjustment is performed using the laser writing frequency of the laser exposure device as an adjustment parameter.

  For adjusting the parallelism, as shown in FIG. 4, a transfer nip width adjusting motor (not shown) for adjusting the nip pressure distribution of the secondary transfer roll 12a and the backup roll 12b in the secondary transfer section 12 is provided. This is done by changing the nip pressure distribution of the secondary transfer roll 12a and the backup roll 12b using a nip width adjusting motor. That is, it is conceivable that the parallelism adjustment is performed using the operation amount of the transfer nip width adjustment motor as an adjustment parameter.

The perpendicularity is adjusted by adjusting the attachment angle of the skew mirror of the laser exposure device in each image forming unit 10 with a mirror drive motor that changes the attachment angle, and the idle roll that stretches the intermediate transfer belt 11. The position is adjusted by a belt displacement motor that displaces the position of the idle roll. However, the main is just adjusting the attachment angle of the skew mirror, and the displacement of the idle roll is used as a sub-adjustment method. Therefore, it is conceivable that the squareness adjustment is performed using the drive amount of the mirror drive motor as an adjustment parameter, and in some cases, the drive amount of the belt displacement motor as an adjustment parameter.
Further, with regard to the adjustment of the arcuate deformation, it can be considered that the amount of displacement for deflecting the optical mirror that reflects the exposure laser in each image forming unit 10 is used as an adjustment parameter.

  As shown in FIG. 5, the skew is adjusted by changing the mounting angle of the side guide 15 provided in the paper transport system in the preceding stage of the secondary transfer unit 12 to a side guide driving motor (not shown). By adjusting by. That is, it is conceivable that the skew adjustment is performed using the drive amount of the side guide drive motor as an adjustment parameter.

  As shown in FIG. 6A, the lead registration is adjusted by adjusting the rotation start timing or the rotation speed of the registration roll 16 that feeds the sheet toward the secondary transfer unit 12 according to the registration roll driving motor that drives the registration roll 16. However, it is performed by adjusting according to (not shown). However, as shown in FIG. 6B, it may be performed by adjusting the laser writing start timing of the laser exposure device in each image forming unit 10. That is, it is conceivable that the lead registration adjustment is performed using the rotation start timing or rotation speed of the registration roll drive motor or the laser writing start timing of the laser exposure device as an adjustment parameter.

  As shown in FIG. 7A, the side registration is adjusted by a side shift motor (not shown) that moves the registration roll 16 in the axial direction to the position of the registration roll 16 that feeds the sheet toward the secondary transfer unit 12. ) To adjust. However, as shown in FIG. 7B, it may be performed by adjusting the laser writing start timing of the laser exposure device in each image forming unit 10. That is, it is conceivable that the side registration adjustment is performed using the drive amount of the side shift motor or the laser writing start timing of the laser exposure device as an adjustment parameter.

  The adjustment of the left / right difference due to the in-out expansion / contraction difference may be performed using the operation amount of the transfer nip width adjustment motor as an adjustment parameter, as in the case of the parallelism adjustment described above.

  Note that the adjustment of the alignment elements mentioned here is merely a specific example, and the adjustment may be performed by a method using other known techniques.

  By the way, the displacement of each alignment element described above can occur due to the following factors. FIG. 8 is an explanatory diagram illustrating an example of the cause of the misalignment. As shown in the figure, there are environmental factors and paper factors that cause misalignment. The environmental factors are environmental factors such as the temperature, humidity, the number of sheets on which image formation has been performed (the number of running sheets), the elapsed time after the operation of the apparatus, and the like. In addition, the paper factor is a factor for paper such as paper type (basis weight, difference in surface treatment, etc.), paper size (A4, A3, etc.), printing surface (front surface or back surface), and the like. Of these environmental factors and paper factors, the environmental factors may change within a single job. Therefore, when processing a job with a large number of prints (for example, 1000 sheets or more), the environmental factor immediately after the start of job processing and the environmental factor immediately before the end of the job change, resulting in a difference in the amount of misalignment. May occur. That is, there is a possibility that the alignment that can occur in a single job is different.

  In order to cope with such a difference in the amount of occurrence of misalignment within a single job, the image forming apparatus 1 described in the present embodiment controls a function for performing the above-described alignment adjustment, that is, a control function for alignment adjustment. Has major features.

  Here, a functional configuration of the image forming apparatus 1 according to the present exemplary embodiment will be described. FIG. 9 is an explanatory diagram showing a functional configuration example of the image forming apparatus according to the present invention. As illustrated, the image forming apparatus 1 includes, in addition to the image forming unit 3, a correction adjustment unit 21, a temperature detection unit 22, a humidity detection unit 23, a time detection unit 24, and a processed number detection unit 25. , An information storage unit 26, a correction amount prediction unit 27, and a setting unit 28.

  The correction adjustment unit 21 performs correction related to image formation when the image forming unit 3 performs image formation. “Correction for image formation” refers to correction for displacement of each alignment element described above, and corresponds to so-called alignment adjustment of a formed image. That is, the correction adjustment unit 21 adjusts the alignment elements described above. However, the correction adjustment unit 21 does not necessarily need to adjust all the alignment elements described above, and may be any one that adjusts at least one of them.

The temperature detection unit 22 detects the temperature in the image forming apparatus 1 including the image forming unit 3 using, for example, a temperature sensor.
The humidity detector 23 detects the humidity in the image forming apparatus 1 including the image forming unit 3 by using, for example, a humidity sensor.
The time detection unit 24 detects an elapsed time from the start of job processing in the image forming apparatus 1, that is, the start of image formation processing in the image forming unit 3, using, for example, a timer function.
The processing number detection unit 25 detects the number of sheets processed in the image forming unit 3 from the start of job processing in the image forming apparatus 1, that is, the start of image forming processing in the image forming unit 3, for example using a counter function. To do.
That is, the temperature detection unit 22, the humidity detection unit 23, the time detection unit 24, and the processing number detection unit 25 are in the state of the image forming apparatus 1, that is, the environmental conditions when the image forming unit 3 performs the image forming operation. Is detected.

The information storage unit 26 describes the amount of correction related to image formation performed by the correction adjustment unit 21 and the state in the apparatus detected by the temperature detection unit 22, the humidity detection unit 23, the time detection unit 24, and the processed number detection unit 25. Information for specifying the relationship is stored using, for example, a nonvolatile memory.
The information stored in the information storage unit 26 is obtained by experimentally outputting continuous images of about 100 to 1000 sheets by the image forming apparatus 1 and measuring the state change in the apparatus at that time and using a scanner device or the like. Thus, the correlation, that is, the information may be specified by obtaining the alignment shift amount in the output result. As an image at this time, it is conceivable to use an image depicting a lattice pattern. The information storage unit 26 stores and holds the information specified in this way at least before starting job processing in the image forming apparatus 1. Specifically, many of the changes occur in the initial stage of printing, and when the running time and number of sheets are accumulated to some extent, the change tends to saturate. It is conceivable to store information such as a curve, a humidity characteristic curve, and a traveling number characteristic curve.
As long as the information storage specifies the relationship between the correction amount and the state in the apparatus, for example, the information can be stored in a table format that enables quick and fine control, or the memory capacity can be reduced. It may be a function type.
The information stored in the information storage unit 26 may be common to the plurality of image forming apparatuses 1 after sampling the plurality of image forming apparatuses 1 and grasping the change tendency of each element. Alternatively, experimental data sampling may be performed for each image forming apparatus 1 at the time of factory shipment, and characteristic data unique to each apparatus may be obtained.

  The correction amount prediction unit 27 is based on the detection results of the temperature detection unit 22, the humidity detection unit 23, the time detection unit 24, and the processed number detection unit 25, and information stored in the information storage unit 26. Predicts the correction amount when performing correction, and instructs the correction adjustment unit 21 of the prediction result. However, the correction amount prediction unit 27 holds time information or processing number information set in advance, and determines the timing of detection result acquisition and correction amount prediction based on the held information. Further, the correction amount prediction unit 27 holds preset threshold information, compares the predetermined threshold specified from the threshold information with the prediction result of the correction amount, and the correction amount prediction result is the predetermined threshold value. Only when the value exceeds the value, an instruction is given to the correction adjustment unit 21.

  The setting unit 28 is used by the user of the image forming apparatus 1 or maintenance personnel to set various information. Examples of the information set by the setting unit 28 include information in the information storage unit 26, time information held by the correction amount prediction unit 27, information on the number of processed images, threshold information, and the like.

  It is conceivable that these units 21 to 28 are realized by an operation program installed in the image forming apparatus 1 operating hardware resources of the image forming apparatus 1. In this case, the operation program may be installed in the image forming apparatus 1 in advance, or may be provided by being stored in a computer-readable storage medium instead of being installed in advance. Or may be distributed via wired or wireless communication means.

  Next, a processing operation example in the image forming apparatus 1 having the above functional configuration will be described. FIG. 10 is a flowchart showing an example of processing operation in the image forming apparatus according to the present invention.

  In the image forming apparatus 1, when a job to be processed using the image forming unit 3 is issued, the correction amount predicting unit 27 includes a temperature detecting unit 22, a humidity detecting unit 23, and a time detecting unit 24 at the start of processing of the job. And the detection result about the state in an apparatus is acquired from each of the process number detection part 25 (step 101, a step is hereafter abbreviated as "S"). Then, the correction amount prediction unit 27 holds these acquisition results until the end of the job.

  Thereafter, the correction amount prediction unit 27 continues to monitor the detection result by either the time detection unit 24 or the processing number detection unit 25, and when the detection result matches the time information or the processing number information, the temperature detection unit again. The detection result about the state in an apparatus is acquired from each of 22 and the humidity detection part 23 (S102). For example, if the correction amount prediction unit 27 is based on time information, the correction amount prediction unit 27 acquires a detection result about the state in the apparatus at every predetermined time specified by the time information. Further, for example, if the processing number information is used as a basis, each time the image forming unit 3 forms a predetermined number of images specified by the processing number information, a detection result about the state in the apparatus is acquired. . In other words, the correction amount prediction unit 27 obtains the detection result of the state in the apparatus at intervals (timing) specified by the time information or the processing number information set by the setting unit 28 and held by the correction amount prediction unit 27. To do.

  And if the detection result about the state in an apparatus is acquired, the correction amount estimation part 27 will calculate | require the correction amount corresponding to the acquired detection result based on the information which the information storage part 26 has memorize | stored. That is, the correction amount prediction unit 27 predicts an alignment deviation amount corresponding to the acquired detection result from the alignment deviation amount characteristic curve stored in the information storage unit 26 (S103).

  After predicting the amount of misalignment, the correction amount prediction unit 27 compares the prediction result with a predetermined threshold specified from the threshold information held by the correction amount prediction unit 27, and whether or not the prediction result exceeds the predetermined threshold. That is, it is determined whether the alignment adjustment amount exceeds the allowable amount and correction by the correction adjustment unit 21 is necessary (S104). As a result, if the alignment deviation amount does not exceed the allowable amount, the job processing in the image forming unit 3 is continued without performing correction by the correction adjustment unit 21. That is, even if the state in the apparatus is regularly monitored, if the necessity for correction is low, the alignment adjustment is not performed, so that the processing load due to the alignment adjustment can be suppressed as much as possible.

  On the other hand, if it is determined that the alignment deviation amount exceeds the allowable amount and correction is required, the correction amount in the correction adjustment unit 21 is calculated and specified from the prediction result of the alignment deviation amount (S105). The correction adjustment unit 21 is instructed to perform correction with the corrected amount (S106). At this time, if the correction amount in the correction adjustment unit 21 has already been set (for example, the default value or the previous correction amount), the correction amount is updated to a newly specified value.

  In response to the instruction from the correction amount prediction unit 27, the correction adjustment unit 21 performs alignment adjustment when the image forming unit 3 performs image formation. At this time, the correction adjustment unit 21 adjusts at least one of the alignment elements described above in accordance with the instruction from the correction amount prediction unit 27. Therefore, since alignment adjustment is performed according to the environmental conditions at the time of performing the image forming operation, it is not necessary to read the formed image for the alignment adjustment, and the alignment adjustment can be easily performed. . In addition, since the state in the apparatus is periodically monitored, and if the state (environmental condition) changes, alignment adjustment can be performed accordingly, even if there is a misalignment that may occur even within a single job. It is possible to make adjustments.

  In a series of processing operations as described above, the image forming apparatus 1 uses a temperature detection unit 22, a humidity detection unit 23, a time detection unit 24, and a processing number detection unit 25 as the state in the apparatus, and a plurality of items are processed. Detection is to be performed. Therefore, the correction amount prediction unit 27 comprehensively predicts the correction amount based on the detection results for these multiple items. However, a plurality of items may be weighted in advance, at least one of the plurality of items may be selected according to the weighting, and the correction amount may be predicted based on the selected detection result.

  Here, the correction amount prediction process based on the detection result of the state in the apparatus will be described with a specific example for each item of the detection result.

First, temperature prediction control will be described. FIG. 11 is an explanatory diagram showing a specific example of the temperature characteristic curve.
When performing the temperature prediction control, it is assumed that the information storage unit 26 stores information on a temperature characteristic curve as shown in FIG. 11, for example. Then, the correction amount prediction unit 27 calculates the difference between the detection result acquired from the temperature detection unit 22 at the start of job processing and the detection result of the temperature detection unit 22 that is periodically sampled. When the deviation amount specified from the temperature characteristic curve exceeds a set allowable amount, the correction adjustment unit 21 is corrected so as to perform correction with a correction amount that cancels the specified deviation amount. Give instructions. The allowable amount can be arbitrarily set from the setting unit 28, but the extent to which the deviation can be seen is a standard. The correction adjustment unit 21 may perform correction every time sampling is performed without performing determination based on the allowable amount. The interval of temperature sampling may be every fixed time or every fixed number of sheets. When performing the relative comparison, a difference with respect to the detection result at the time of the previous alignment adjustment may be calculated instead of the detection result at the start of job processing.
As a specific example, for example, correction of the lateral magnification of an image will be described. In general, as a factor causing a change in lateral magnification, a change in the optical path length of a laser exposure device can be cited. On the other hand, when a temperature change occurs in the apparatus, the constituent members in the apparatus and the paper itself may expand and contract. Such expansion and contraction causes a change in the scanning length of the laser beam. Therefore, in alignment adjustment (laser writing frequency adjustment) before the start of job processing, even if the adjustment is set as a default value, it follows the temperature characteristic curve in the information storage unit 26 after the start of job processing. Meanwhile, the correction amount is finely adjusted according to the state in the apparatus. If the clock cycle of the laser writing frequency is delayed, the formed image is stretched, and conversely, if the clock cycle is shortened, the formed image is shrunk, so that the lateral magnification can be changed.

Next, humidity prediction control will be described.
The change in humidity mainly causes a change in the vertical (sub-scanning direction) magnification accompanying the expansion and contraction of the paper during fixing. Therefore, when performing the humidity prediction control, the correction amount prediction unit 27 predicts the correction amount by obtaining the detection result of the humidity detection unit 23 by periodic sampling as in the case of the temperature prediction control described above, and the prediction When the result exceeds the allowable amount, the correction adjustment unit 21 is caused to perform alignment adjustment (speed adjustment of the belt drive motor). In this case, the expansion / contraction amount of the paper greatly depends on the moisture content of the paper. Therefore, it is desirable that the humidity detection unit 23 detects the humidity in the apparatus using a humidity sensor arranged in the paper tray in the paper supply unit 4. In addition, when there are multiple paper trays, a humidity sensor is provided for each tray, so that alignment adjustment is performed with a correction amount suitable for the expansion and contraction of the paper in the tray, regardless of the tray from which the paper is supplied. Can do. Also, depending on the water vapor saturation state in the apparatus, the paper length at the time of printing on the back surface of the paper changes. Therefore, a humidity sensor may be arranged around the fixing unit 13 or near the paper reversal carrying path.

Next, output number prediction control will be described. FIG. 12 is an explanatory diagram showing a specific example of the running number characteristic curve.
For example, changes in parallelism and changes in side skew are mainly due to the fact that oil adhering to the paper during fixing reattaches to the paper conveyance system roll, transfer belt or roll, and the coefficient of friction with the paper changes. Caused by. For such misalignment, for example, information related to the running sheet characteristic curve in which the number of sheets running from the start of job processing and the amount of alignment change as shown in FIG. The correction amount prediction unit 27 may predict the correction amount while referring to the travel number characteristic curve in the information storage unit 26.
However, in this case, the oil adhering to the roll volatilizes with time, so it is necessary to consider the interval between jobs. For example, if multiple types of running number characteristic curves are prepared in advance and a plurality of jobs are processed in succession, a correction operation is performed on the assumption that the job to be performed later drags the previous state. If multiple jobs are processed with a certain interval, it is considered that the oil has dried out during each job in later jobs, so select the characteristic curve at the start of job processing. For example, a correction operation is performed. In this case, the threshold value of the job interval can be arbitrarily set from the setting unit 28.

Next, the elapsed time control will be described.
In the prediction correction by the temperature prediction control described above, in the temperature correction by the temperature sensor, the temperature is detected using a temperature sensor arranged at a specific place (a place where the relationship between the temperature change and the deviation amount is relatively stable). Therefore, it cannot be said that this detection result is representative of all temperature distributions in the apparatus. Therefore, for example, when a temperature sensor is arranged in the vicinity of the fixing unit 13, the adjustment of the site according to the temperature rise due to fixing in the fixing unit 13 can be handled by correction by the temperature sensor. It is not possible to cope with the adjustment due to the temperature rise in the part away from 13. Therefore, a characteristic curve that associates the amount of change over time, that is, a characteristic curve that takes into account the distance from the temperature sensor and heat propagation, is prepared, and the characteristic curve is selected according to the alignment element to be adjusted. It can also be used.

  As described above, the correction amount prediction processing may be performed by at least one of temperature prediction control, humidity prediction control, output number prediction control, or elapsed time control, or a combination of these. However, when a plurality of items are combined, detection of a plurality of items is performed as a state in the apparatus, and a correction amount is predicted based on a detection result of the plurality of items and stored information in the information storage unit 26. Assumed to be performed. Even if the state in the device can change in a complex manner by combining multiple items, it is based on the detection results for multiple items, so the state in the device that can change in a flexible and accurate manner is determined. Can be predicted. In this case, it is conceivable that the storage information in the information storage unit 26 obtains one prediction result from the detection results of a plurality of items. However, it is also possible to obtain one prediction result from the detection result of one item, that is, to obtain the prediction result for the number of items if there are detection results of a plurality of items, in which case the correction amount according to a predetermined standard The prediction unit 27 may select any one prediction result. For example, one prediction result is selected according to the priority order set for each item, or the one with the maximum correction amount as the prediction result is selected.

  Also, there may be a plurality of types of information stored in the information storage unit 26 such as various characteristic curves for the detection result of one item. In this case, the correction amount prediction unit 27 selects one of the storage information related to a plurality of types of characteristic curves, and predicts the correction amount based on the storage information related to the selected characteristic curves. Shall. The selection of the storage information related to the characteristic curve is based on preset criteria, more specifically, on the type of alignment element to be adjusted, the elapsed time from the start of the job, the job processing content, etc. You just have to do it. For example, when performing double-sided printing, different characteristic curves are selected for the front side and the back side. In this way, if any one of a plurality of types of stored information is selected and the correction amount is predicted, the processing form in the image forming unit 3 can be handled flexibly and accurately, such as when performing double-sided printing. The correction amount can be predicted.

  In the present embodiment, the preferred specific examples of the present invention have been described. However, the present invention is not limited to the contents, and can be appropriately changed without departing from the gist thereof.

1 is an explanatory diagram illustrating a schematic configuration example of an image forming apparatus according to the present invention. It is explanatory drawing which shows the specific example of an alignment element. It is explanatory drawing (the 1) which shows the specific example of alignment adjustment, and is a figure which shows the outline | summary of horizontal magnification adjustment. It is explanatory drawing (the 2) which shows the specific example of alignment adjustment, and is a figure which shows the outline | summary of parallelism adjustment. It is explanatory drawing (the 3) which shows the specific example of alignment adjustment, and is a figure which shows the outline | summary of skew adjustment. It is explanatory drawing (the 4) which shows the specific example of alignment adjustment, and is a figure which shows the outline | summary of lead registration adjustment. It is explanatory drawing (the 5) which shows the specific example of alignment adjustment, and is a figure which shows the outline | summary of side registration adjustment. It is explanatory drawing which shows the example of the generation | occurrence | production factor of misalignment. It is explanatory drawing which shows the function structural example of the image forming apparatus which concerns on this invention. 4 is a flowchart illustrating an example of processing operation in the image forming apparatus according to the present invention. It is explanatory drawing which shows a specific example of a temperature characteristic curve. It is explanatory drawing which shows a specific example of a running number characteristic curve.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 2 ... Image reading part, 3 ... Image forming part, 4 ... Paper supply part, 5 ... Paper discharge part, 6 ... Control part, 10 ... Image forming unit, 11 ... Intermediate transfer belt, 12 ... Two Next transfer section, 12a ... secondary transfer roll, 12b ... backup roll, 13 ... fixing section, 15 ... side guide, 16 ... registration roll, 21 ... correction adjustment section, 22 ... temperature detection section, 23 ... humidity detection section, 24 ... Time detection unit, 25 ... Processed number detection unit, 26 ... Information storage unit, 27 ... Correction amount prediction unit, 28 ... Setting unit

Claims (12)

Image forming means for forming an image on paper;
Correction adjustment means for performing correction related to image formation when the image forming means performs image formation;
State detection means for detecting a state in the apparatus including the image forming means;
Information storage means for storing information on the relationship between the amount of correction relating to the image formation and the state in the apparatus;
A correction amount prediction unit that predicts a correction amount when the correction adjustment unit performs correction based on a detection result of the state detection unit and information stored in the information storage unit and instructs the correction adjustment unit. An image forming apparatus comprising the image forming apparatus. The state detection means detects a plurality of items as the state in the device,
The image forming apparatus according to claim 1, wherein the correction amount prediction unit predicts the correction amount based on a detection result of the plurality of items and information stored in the information storage unit. . The image forming apparatus according to claim 1, wherein the state detection unit detects a temperature in the apparatus as a state in the apparatus. The image forming apparatus according to claim 1, wherein the state detecting unit detects humidity in the apparatus as a state in the apparatus. The image forming apparatus according to claim 1, wherein the correction amount predicting unit predicts the correction amount every predetermined time. 5. The correction amount prediction unit predicts the correction amount each time the image forming unit forms a predetermined number of images. 5. Image forming apparatus. The image forming apparatus according to claim 5, further comprising a setting unit configured to set a correction amount prediction timing by the correction amount prediction unit. The image forming apparatus according to claim 1, wherein the information storage unit stores information in a table format. The image forming apparatus according to claim 1, wherein the information storage unit stores information in a function format. The correction amount prediction unit compares the predicted correction amount with a predetermined threshold value, and gives an instruction of the correction amount to the correction adjustment unit only when the correction amount exceeds the predetermined threshold value. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. The correction amount predicting means is based on the difference between the reference and the new detection result by the state detecting means, based on the detection result of the state detecting means based on the previous correction execution by the correction adjusting means. The image forming apparatus according to claim 1, wherein the correction amount is predicted. The information storage means stores information on the relationship between the amount of correction relating to the image formation and the state in the apparatus for a plurality of types of relationships,
The correction amount prediction means selects any one of the plurality of types of relationships and predicts the correction amount based on information about the selected relationship. The image forming apparatus according to any one of 1 to 11.

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