JP2005145700A - Image forming device, controller, control method, and control program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable grasping of variation with time of printing image quality, when printing processing is applied to a plurality of paper sheets in an image forming processing. <P>SOLUTION: Conveying timing of paper sheets 480 and 482 and forming timing of images 470 and 472 formed by corresponding printing processing are controlled to coincide with a rotation period of rotators for printing such as a photo conductor drum 22a and an electrostatic charge roller 24a. Thus, respective places where concentration unevenness or the like occurs based on a physical factor of the rotator for printing in the paper sheets are matched with each other. Thus, the variation with time of printing image quality is easily grasped based on inspection image data obtained by reading a printing image with a reading sensor 74. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a control technique in the case where printing is performed on a conveyed sheet using a printing rotator, and more particularly to a technique for sharing printing conditions caused by a printing rotator.

  For example, in an image forming apparatus using an electrophotographic system, a print image is printed on a sheet by using a rotary member for printing such as a photosensitive drum, a transfer roller, a developing roller, and an intermediate transfer member. In the printed image, there may be a non-uniformity such as a density related to the rotation of the printing rotating body.

  Japanese Patent Application Laid-Open No. 2004-228561 prevents the unevenness of density due to each printing rotating body from occurring irregularly at different locations by increasing the outer peripheral ratio between the intermediate transfer member and the photosensitive drum to an integral multiple. Technology is disclosed. Japanese Patent Application Laid-Open No. 2005-228561 describes contents that simplify the cycle in which density fluctuations occur by making the diameters of the photosensitive drum, charging roller, developing roller, and transfer roller the same. Here, correction is performed based on the reading result of the image on the intermediate transfer member, and density unevenness or the like caused by each printing rotating member is prevented from occurring in different places.

JP-A-6-202492 Japanese Patent Laid-Open No. 10-20579

  It is desirable that the image forming apparatus can print a print image having the same quality on a large number of sheets such as several tens of sheets. However, if density unevenness or the like due to the rotating body for printing occurs at different locations during printing, there arises a problem of non-uniform image quality that the quality of the printed image on each paper is different. In addition, in the case of controlling the change in the image quality of the print image based on the inspection image data obtained by reading the print image, whether the change in the image quality found is a change caused by the rotating body for printing, There arises a problem in the temporal change inspection that it is difficult to determine whether the result is a change with time due to printing. However, this problem cannot be solved by the techniques of Patent Documents 1 and 2 above.

  An object of the present invention is to make common the printing conditions of the rotary body for printing on paper in the image forming process.

  Another object of the present invention is to find a change with time in printing based on inspection image data.

  The image forming apparatus of the present invention includes a paper transport path for transporting paper according to the transport timing, and a rotating body for printing that rotates corresponding to the transport of the paper, and the paper transport according to the print processing timing corresponding to the transport timing. A printing unit that performs a printing process on a sheet using a surface of the printing rotating body on a road; and a control unit that controls the conveyance timing and a corresponding printing process timing. For one sheet, the conveyance timing and the corresponding printing process so that the corresponding part on the surface of the printing rotating body for the sheet coincides with the corresponding part for a certain sheet on which printing processing has been performed previously. A coincidence control means for controlling the timing is provided.

  The image forming apparatus is an apparatus that forms a print image on paper based on electronic image data, such as a printer or a copying machine. The paper transport path is a path for transporting unprinted paper to the printing unit and further transporting it to a printed paper storage area. A path for duplex printing may also be included. The printing unit is a part that performs a printing process based on image data and prints a print image on paper. Printing may be monochrome or color. The printing method is not particularly limited as long as the printing method includes a plurality of rotating rotating bodies for printing such as an electrophotographic method and an inkjet method. The rotator for printing is a rotator directly related to the printing process using its surface. Taking an electrophotographic method as an example, a rotator having an image forming surface such as a photosensitive drum or an intermediate transfer member, Examples thereof include an image forming rotator such as a roller and a developing roller, a transfer rotator such as a transfer roller, and a printing result fixing rotator such as a fixing roller. The paper refers to not only so-called paper made from plant fibers but also general printed matter including synthetic fibers and OHP sheets, and the size and thickness are not particularly limited.

  The control unit controls the transport timing for transporting the paper and the corresponding print processing timing so that the printing process in the printing unit is performed on an appropriate portion of the transported paper. The coincidence control means is configured so that a corresponding portion on the surface of the printing rotator for a certain sheet and a corresponding portion on the surface of the printing rotator for another certain sheet that has undergone printing processing are matched. It controls the timing for transporting the paper and the corresponding print processing timing. As a result, the printing on the two papers that are transported and printed is performed by the physically same part of the printing rotating body (of course, it may include a slight deviation such as an error due to control). Become. Therefore, the physical printing conditions of the rotary body for printing on these two sheets can be made uniform. The coincidence control means may adjust the rotation speed of the rotary body for printing to match the corresponding portions, but from the viewpoint of avoiding a decrease in printing accuracy, the speed of the rotary body for printing is constant. It is particularly desirable to perform control as

  According to this configuration, the corresponding portions on the surface of the printing rotator corresponding to the sheets coincide with each other in the sheets to be controlled. Therefore, when there is a disturbance in the image quality due to the printing rotator, it appears at the same portion. . Therefore, even when printing is performed on a large number of sheets, it is possible to maintain the same image quality between the sheets. It is also easy to detect changes over time. The contents of the print image, that is, the contents of the image data used for creating the print image may be completely different from each other, but it is particularly preferable that they are completely the same or partially the same.

  In order to perform this control, the coincidence control unit, for example, includes rotation timing information (such as information about a rotation period and angle position information of a specific portion) of a target printing rotating body, and paper conveyance timing information (conveyance). Information related to the cycle, position information of the paper in the conveyance path, size (length) information, etc.), print timing information (information related to the cycle of the printing process, and information on which part of the rotating body for printing is printed) Etc.), necessary information can be acquired from the information such as the corresponding part information of the printing rotator for the past paper. Although the user may set the selection of the paper to be controlled each time, it is preferable to automatically perform the setting based on the programming content. In setting, it is particularly desirable to set the control so that the corresponding portions of the printing rotating body for each sheet coincide with each other, including every other sheet (that is, all sheets). As a result, it is possible to obtain a sheet printed under the same conditions periodically, and to monitor the printing accuracy and the like under the same conditions periodically. In addition, the user may set the selection of a specific sheet for which printing processing has been performed before that time, but it is preferable to automatically set it based on the contents of programming. Note that the selection of the specific sheet does not need to be selected from a series of groups that are successively conveyed by one job command or the like. For example, in order to standardize a plurality of sets of printing conditions performed with interruptions such as paper replenishment, it is possible to set the first sheet of the first group. It is also effective to always set the corresponding location of the printing rotator for the first sheet of each set as a predetermined location.

  Preferably, in the image forming apparatus of the present invention, the control unit controls the conveyance timing and the corresponding print processing timing for each sheet earlier than the conveyance timing and the corresponding print processing timing controlled by the coincidence control unit. Thus, a normal printing control unit that improves the efficiency of the printing process, and a switching unit that switches between the coincidence control unit and the normal printing control unit are provided.

  The early and late of the transport timing and the corresponding print processing timing are measured by how long after the transport and print processing for the previous paper is performed, the target paper transport and print processing are performed. be able to. Since the conveyance timing and the corresponding print processing timing realized by the coincidence control unit are generally later than the limit timing defined by the printing unit or the paper conveyance path, the efficiency of the printing process is reduced. Therefore, when there is little need to consider common printing conditions, or when it is desired to improve printing processing efficiency, control by the coincidence control means is not performed. Instead, it is defined by the printing unit or paper transport path. It is desirable that the sheet conveyance and printing process can be executed at an appropriate timing until reaching the limit timing. The normal printing control means is provided based on this viewpoint. From another viewpoint, it is considered that a general image forming apparatus having a normal printing control unit for efficient processing is incorporated with an option that enables matching of corresponding parts by adding a matching control unit. be able to. Note that the control content to be switched by the switching unit need not be limited to two, and can be set in other ways.

  Preferably, in the image forming apparatus of the present invention, the printing unit includes at least two printing rotators that rotate at mutually different rotation cycles, and the coincidence control unit is configured to change from a printing rotator having a certain rotation cycle to another one. Changing means for changing a control object to a printing rotating body having a rotation cycle is provided. That is, in general, it is desirable to select a printing rotator that is most likely to cause unevenness in image quality such as density fluctuations as a target printing rotator, but other printing rotators should be appropriately controlled. Can do. For example, in the case of the electrophotographic system, when the photosensitive drum and the developing roller rotate with mutually different rotation cycles, a target to be matched in each sheet every predetermined number of sheets is set as a corresponding portion of the photosensitive drum or a corresponding portion of the developing roller. You can select and change.

  The change may be performed by a user's instruction or automatically according to a program. For example, when periodic image quality disturbance is found based on the inspection result of an image, it is effective to set so that the rotating body for printing having a rotation period corresponding to the period is targeted. When changed, the sheet to be controlled may be changed at the same time. For example, a predetermined number of sheets that are matched every predetermined number of sheets can be changed to another predetermined number. Specifically, when the paper conveyance interval becomes large with the previous predetermined number of sheets and the printing processing efficiency is lowered, the new predetermined number of sheets is determined so as to be within a predetermined conveyance interval (conveying cycle). An example can be given. According to this configuration, when a plurality of printing rotators have different rotation periods, the rotation rotator to be synchronized by the changing unit is changed to identify the printing rotator that causes image quality disturbance. In addition, it becomes easy to detect a change with time excluding the influence of the printing rotating body.

  Preferably, in the image forming apparatus of the present invention, the printing unit includes at least two printing rotators that rotate synchronously at the same rotation period, and the coincidence control unit controls the two printing rotators. Control as a target. In the case where some of the plurality of printing rotators are rotating synchronously with the same rotation period, the portions of these printing rotators correspond to each other. By controlling the control unit so that the corresponding portions of the paper in the printing rotator coincide with each other, the problem of inhomogeneity in image quality and the problem of temporal change inspection caused by these rotators for printing are collectively dealt with. It becomes possible to do. From this point of view, it is preferable that the plurality of rotating bodies are designed so as to have the same rotation period, or to have a rotation period that is a natural number multiple (1 / natural number).

  Preferably, in the image forming apparatus of the present invention, the coincidence control unit is configured to control the conveyance timing of each sheet so that the ratio of the conveyance period in which each sheet is conveyed to the rotation period of the printing rotator is kept at a rational number. And control the corresponding print processing timing. That is, the coincidence control unit controls the paper transport interval and the corresponding print processing interval so that the ratio of the paper transport cycle to the rotation cycle of the printing rotator is kept at a rational number (an integer corresponding to an integer). For example, when the rotation period is 1 second and the conveyance period is 3 seconds, that is, the ratio is 1/3, one sheet is conveyed while the target printing rotator is rotated three times. In this way, when the numerator in the irreducible fraction display is 1, the corresponding portions of the target printing rotator with respect to the paper for all the papers coincide with each other. For example, when the ratio is 3/1, three sheets of paper are conveyed while the target rotating body for printing is rotated once. In this way, when the denominator in the irreducible fraction display is represented by 1, there is a corresponding portion of at least one printing rotator for each sheet for each sheet for every denominator minus one (every two in this example). Match. In addition, when 1 does not appear in the denominator or the numerator in the irreducible fraction display, such as a ratio of 3/2 or 2/3, every product of the numerator and denominator minus one (both 5 in this example). Every other sheet) corresponds to the corresponding portion of the target printing rotator for each sheet. In this way, by making fine settings so that the ratio between the rotation period and the conveyance period is a rational number, control that achieves both synchronization every predetermined number of sheets and prevention of decrease in printing efficiency for various sizes of paper. It becomes possible to do. Since there is a normal error in control, the ratio between the two can usually be regarded as an approximate rational number only, and there is a concern that it cannot be distinguished from an irrational number in the first place. However, those skilled in the art have the intention of the present invention to match corresponding parts every common number of sheets (for example, about 100 sheets or less, preferably about 10 sheets or less), and perform such control. You can see that the ratio is expressed as a rational number.

  Preferably, in the image forming apparatus of the present invention, the coincidence control unit performs control for all sheets conveyed one after another. As a result, it is possible to perform printing with the same physical conditions of the printing rotator on a series of all sheets conveyed one after another. Therefore, it is possible to take measures to solve the problem of inhomogeneity in image quality and the problem of inspection over time for all sheets. In particular, in a normal image forming apparatus, printing on a plurality of papers progresses until the result of image quality inspection or the like is fed back to the printing process. Therefore, in order to shorten the blank time from the occurrence of a problem to the feedback, It is desirable to control the paper. Further, for example, when the inspection is performed only on a part of the sheets, it is not necessary to select a comparable sheet when selecting the part of the sheets, and the inspection is performed on the arbitrarily selected sheets. It becomes possible.

  Preferably, in the image forming apparatus of the present invention, an inspection for performing image quality inspection using inspection image data obtained by reading a print image printed on the paper by the printing unit, with respect to the paper corresponding to the corresponding portion. Means. The inspection image data is electronic data generated by reading a print image printed on a sheet with a reading device such as an image scanner. This reading device may be attached to the image forming apparatus or may be attached to the outside. The inspection means acquires inspection image data, and inspects the image quality for a sheet having the corresponding corresponding part. As a result, it is possible to perform the inspection while eliminating the influence of density unevenness and color unevenness that occur periodically with the rotation of the printing rotator as a target in the coincidence control means.

  As inspection contents, various types of inspections known in the past can be used. In particular, in the electrophotographic method in which the image density inspection tends to cause a change over time, a plurality of sheets are inspected. This is important for stable printing. Although the inspection can be performed by extracting information from only the inspection image data depending on the inspection contents, it is preferable to compare with appropriate image data when examining the change over time. As reference image data, when printing on a plurality of sheets, an example of selecting inspection image data corresponding to the first printed sheet, or an image based on when the printing unit performs printing An example of selecting data can be given.

  It is also possible to perform feedback processing for adjusting the printing processing content of the printing unit based on the inspection result. For example, when the density of the blue component decreases with time, the temporal change can be eliminated by increasing the density of the blue component in the printing unit. The feedback process can be performed in various forms such as switching the output LUT (lookup table) and changing the development potential.

  The control apparatus according to the present invention includes a paper transport path for transporting paper according to the transport timing, and a rotating body for printing that rotates corresponding to the transport of the paper, and is on the paper transport path according to a print processing timing corresponding to the transport timing. A control unit that controls the image forming system including a printing unit that performs a printing process on the sheet by using the surface of the rotating body for printing, the sheet conveying path and the printing from the image forming system Operation information acquisition means for acquiring operation information related to the rotating body for control, control instruction means for generating a signal for controlling the conveyance timing and the corresponding print processing timing based on the operation information, and transmitting the signal to the image forming system The control instructing means has at least one corresponding position on the surface of the rotary body for printing with respect to at least one sheet. Wherein for a sheet subjected to printing processing to match the corresponding portion, and a match control instruction means for generating a control signal of a printing process timing at which the conveying timing and the corresponding.

  Preferably, in the control device of the present invention, the image forming system includes an inspection unit that performs an image quality inspection using inspection image data obtained by reading a print image printed on the paper by the printing unit, The control device includes an inspection instructing unit that instructs the image forming system to perform an image quality inspection by the inspection unit on a sheet of which the corresponding part matches. Preferably, the control apparatus according to the present invention includes an inspection result acquisition unit that acquires a result of an image quality inspection performed based on the inspection instruction unit from the image forming system, and the image based on the acquired inspection result. Adjustment instruction means for instructing the forming system to adjust the printing process.

  This control device is a device that controls the operation of the image forming system. The image forming system may be configured using a single casing, or may be configured by connecting a plurality of casings by communication means. The control device may be built in the image forming system or may be installed separately. In the case of being built in, an arithmetic processing unit dedicated to the control device may be provided, or the image forming system and the arithmetic processing unit may be shared. Moreover, when installing separately, it can comprise using general PC (personal computer) etc., for example. The control device may be directly connected to the image forming system or may be connected via a network.

  The control method of the present invention includes a paper transport path for transporting paper according to the transport timing, and a rotating body for printing that rotates corresponding to the transport of the paper, and is arranged on the paper transport path according to the print processing timing corresponding to the transport timing. A computer that controls an image forming system including a printing unit that performs a printing process on a sheet by using a surface of the rotating body for printing, the paper transport path and the paper from the image forming system An operation information acquisition step for acquiring operation information relating to the rotating body for printing, and a control instruction step for generating a signal for controlling the conveyance timing and the corresponding print processing timing based on the operation information and transmitting the signal to the image forming system The control instruction step includes, for at least one sheet, a table of the printing rotator for the sheet. As the corresponding part of the upper match with the corresponding portion for a sheet subjected to the printing process before that, including a match control instruction step of generating a control signal of a printing process timing at which the conveying timing and the corresponding.

  The control program of the present invention has a paper transport path for transporting paper according to the transport timing and a rotating body for printing that rotates corresponding to the transport of the paper, and is on the paper transport path according to the print processing timing corresponding to the transport timing. And a printing unit that performs a printing process on a sheet by using the surface of the printing rotating body, the program controlling the image forming system from the image forming system to the sheet conveyance path and the printing An operation information acquisition procedure for acquiring operation information relating to the rotating body, a control instruction procedure for generating a signal for controlling the conveyance timing and the corresponding print processing timing based on the operation information, and transmitting the signal to the image forming system; The control instruction procedure includes, for at least one sheet, a corresponding location on the surface of the printing rotating body for the sheet. To match the corresponding portion with respect to a particular paper done it before print processing, including matching control instruction step of generating a control signal of a printing process timing at which the conveying timing and the corresponding.

  Embodiments of the present invention will be described below.

  FIG. 1 is a block diagram showing an outline of a device configuration according to the present embodiment. Here, an image forming system including the image forming apparatus 10 and the inspection / control apparatus 100 directly connected to the image forming apparatus with a cable will be described as an example. The inspection / control apparatus 100 is connected to a LAN 200, and a client PC 300 of a general user is also connected to the LAN 200. The image forming system is a system that executes print processing based on a print job command sent from the client PC 20.

  The image forming apparatus 10 is an apparatus that actually performs print processing in the image forming system, and operates under the control of the inspection / control apparatus 100. The main configuration includes a printing unit 20 that prints on a sheet, a sheet conveyance path 50 that conveys the sheet, and an inspection image data generation unit 70 that reads the print image printed on the sheet and generates inspection image data. .

  The printing unit 20 performs color printing processing using an electrophotographic method. In the electrophotographic system, first, a charge is applied to the surface of the photosensitive drum 22 using the charging roller 24. Then, the exposure unit 26 irradiates light based on the image data to release charges, thereby forming an electrostatic latent image on the surface of the photosensitive drum 22. The timing of this light irradiation, that is, the timing of the printing process is performed in accordance with the conveyance timing of the paper. Next, processing for developing the electrostatic latent image using toner that is charged powder is performed by the developing roller 28. In color printing, the above processing is typically performed for each color. That is, the photosensitive drum 22 or the like is prepared for each color, and development corresponding to the color is performed.

  Subsequently, the image revealed by the development is transferred to the intermediate transfer body 32 by using an electric force using the transfer roller 30. In the case of color printing, transfer is performed so that the images of the respective colors overlap. The image formed on the intermediate transfer member is transferred onto the paper by the secondary transfer roller 34. The fixing roller 36 is heated and pressed to form a print image on the paper.

  In many of these configurations, each processing is generally performed while rotating according to the sheet to be conveyed, and can be called a rotating body for printing. That is, the photosensitive drum 22, the charging roller 24, the developing roller 28, the transfer roller 30, and the fixing roller composed of two rotating bodies sandwiching the paper are usually formed in a cylindrical shape, and are prepared for each color. It is a rotating body for printing that rotates according to conveyance. The intermediate transfer body 32 is a printing rotating body configured in a wide belt shape that rotates in accordance with the conveyance of the paper. When there is a belt seam in the intermediate transfer member 32, the paper feeding interval is generally made so that the paper does not overlap the belt seam. However, if the belt is seamless and seamless, the paper feeding cycle is not constrained by the belt rotation cycle.

  The rotational driving of these printing rotators is generally constant speed, and is performed with a rotation period corresponding to each size. A sensor 38 can be provided in order to grasp the situation of this rotational movement, that is, the rotation cycle, the rotation angle at a specific location, and the like.

  The paper transport path 50 is a path for transporting paper. A take-in unit 52 is provided that takes in paper from a paper tray on which unprinted paper is set at a timing corresponding to the print processing timing. The captured paper is transported along a route to a printed paper storage place by a paper feed mechanism provided at various locations on the paper transport path 50. The secondary transfer and fixing processing in the printing unit 20 and the processing in the inspection image data generation unit 70 described below are performed on the paper being conveyed. The paper transport path 50 is provided with a sensor 54 for grasping the position of the paper being transported, and the timing of feeding to the printing unit 20 can be adjusted based on the detection result. In this way, the paper transport path 50 can transport paper of various sizes at various timings corresponding to the print processing timing.

  The inspection image data generation unit 70 performs a print image reading process on the paper that has been printed on the paper transport path 50 and generates inspection image data. For this purpose, a lamp 72 that illuminates the printed image with light and a reading sensor 74 that converts reflected light from the printed image into an electrical signal are provided. Thus, by obtaining inspection image data that is electronic information based on the image information of the print image, it is possible to easily perform image quality inspection of the print image.

  Next, an outline of the configuration of the inspection / control apparatus 100 will be described. The inspection / control apparatus 100 is an apparatus that controls the image forming apparatus 10 and inspects the print processing result performed by the image forming apparatus 10. For example, the inspection / control apparatus 100 describes the contents of the inspection / control for a general PC or the like. This can be realized by installing an application program. The inspection / control apparatus 100 includes a control unit 110, a storage unit 130, a user setting unit 140, an image quality inspection unit 150, and the like as main components.

  The control unit 110 is a part constituted by hardware such as an MPU and a main storage device and software such as a program for defining the operation content, and controls the operation of the inspection / control device 100 itself and also the image forming apparatus. 10 control is also performed.

  One of the very characteristic features of the control unit 110 is that it includes a coincidence control unit 112. In the printing process in the printing unit 20, the coincidence control unit 112 sets the position on the paper corresponding to the physical location of at least one printing rotating body for a certain sheet to another sheet on which printing has been performed previously. On the other hand, control is performed so that the physical location of the printing rotating body coincides with the corresponding position on the paper. For example, when the printing rotator to be controlled is the photosensitive drum 22, printing on the two sheets is performed by an image formed from a specific location on the outer periphery of the photosensitive drum 22 to another specific location. Will be made. The coincidence control unit 112 typically instructs the sheet conveyance path 50 to convey the sheet so that the rotation cycle of the target printing rotator is equal to the sheet conveyance cycle, and at an interval corresponding to this interval. The exposure unit 26 instructs the photosensitive drum 22 to form a latent image. This makes it possible to align the corresponding portions of the printing rotator on each sheet. It is also effective to simply match the rotation period and the conveyance period from a time point of view. However, when printing is performed on a large number of sheets, errors gradually accumulate and the rotation of the printing rotating body on the sheet gradually increases. Corresponding parts may be shifted. Therefore, based on the result of monitoring the position of the actually conveyed paper by the sensor 54 and the result of monitoring the rotation angle of the corresponding portion of the printing rotating body by the sensor 38, the rotation cycle from a spatial viewpoint. It is also effective to match the conveyance cycle.

  Each printing rotator generally has a different rotation period. Therefore, the coincidence control unit 112 includes a changing unit 114. The changing unit 114 changes the printing rotator to be controlled, and changes the processing timing of the exposure unit 26 and the corresponding conveyance timing of the paper conveyance path 50 in accordance with the rotation cycle of the printing rotator.

  The normal printing control unit 116 controls the sheet conveyance interval and the corresponding printing processing interval so as to increase the printing processing efficiency. That is, the normal print control unit 116 selects the paper transport timing and the corresponding print processing timing without being constrained by the matching condition of the physical location of the printing rotator. Therefore, it functions effectively in normal printing in which the difference in the physical location of the rotating body for printing is not a problem. The switching unit 118 switches between control by the coincidence control unit 112 and control by the normal print control unit 116. The switching may be performed by the user or may be performed automatically under programmed conditions. For example, the coincidence control unit 112 is automatically selected in the high-quality printing mode, and the normal print control unit 116 is automatically selected in the standard processing mode, the low-quality printing mode, or the high-speed printing mode. It is possible to set.

  The image quality adjustment control unit 120 issues an inspection image data generation instruction to the inspection image data generation unit 70 and an image quality inspection instruction using the inspection image data to the image quality inspection unit 150. Then, based on the inspection result, an adjustment instruction for improving the image quality is issued to the printing unit 20.

  The storage unit 130 is configured by a storage device such as a semiconductor memory or a hard disk. Although various data can be stored, one characteristic point is that the image data 132 for printing sent from the client PC 300 is set to be able to be held. Another characteristic point is that the inspection image data generated by the inspection image data generation unit 70 is set so as to be retained.

  The user setting unit 140 is provided for the user to instruct control of the inspection / control apparatus 100 or the image forming system using an input unit such as a keyboard. The user's instruction can be set so as to be issued from the client PC 300 or the image forming apparatus 10.

  The image quality inspection unit 150 can inspect the image quality of the inspection image data 134 from various viewpoints based on an instruction from the image quality adjustment control unit 120. For example, the inspection image data 134 may be compared based on the comparison of the corresponding image data 132, or the inspection image data 134 corresponding to a plurality of print images may be compared. It is also possible to perform inspection only with the inspection image data 134 corresponding to one print image. Also, the contents of the image quality inspection can be various, for example, a so-called white spot or character missing inspection in which toner is not placed in the place where it should be, or a print density inspection including the density of each color. it can. One of the characteristic matters in the present embodiment is that an image quality inspection such as density is performed on the paper whose corresponding portions of the printing rotator coincide with each other under the control of the coincidence control unit 112, and the change with time is inspected. It is possible to do that. In each sheet, image quality disturbance such as density unevenness may occur due to physical factors at appropriate portions of the printing rotating body. If this disturbance in image quality occurs at different positions on each sheet, it is difficult to grasp the change in density over time. However, in the paper subjected to the coincidence control, the image quality is disturbed at the same location on the paper, so that it is easy to inspect changes with time.

  In addition to the configuration of the image forming system described above, various image forming systems can be formed. For example, the image forming system may be configured not to include the inspection function, or may be configured to be included in a housing in which the image forming apparatus and its control unit are integrated.

  Next, the present embodiment will be described using a simplified cross-sectional view (FIGS. 2 and 4) of a main part of the image forming apparatus 10 and a schematic diagram of corresponding image quality inspection results (FIGS. 3 and 5). This will be described in detail. In the description, first, the situation controlled by the normal printing control unit 116 will be described with reference to FIGS. 2 and 3, and then the situation controlled by the coincidence control unit 112 will be described with reference to FIGS. 4 and 5.

  FIG. 2 is a simplified view of the cross section of the image forming apparatus 10 that performs CMYK four-color printing. Corresponding to these four colors, four photosensitive drums 22a, 22b, 22c, 22d, charging rollers 24a, 24b, 24c, 24d, developing rollers 28a, 28b, 28c, 28d, transfer rollers 30a, 30b, 30c and 30d are provided. Then, the images 410, 412, 414, 416,... Are supported on the intermediate transfer body 32 supported by the support rollers 400, 402, 404, and 406 and rotating clockwise. . . Will be formed. The intermediate transfer member 32 is moving at the same speed from the right to the left in the drawing at a slight angle with the rectilinear portion 420 constituting the sheet conveyance path 50 below the intermediate transfer member 32. This rectilinear portion 420 includes images 410, 412, 414, 416,. . . 430, 432, 434, 436,. . . Is transferred, and transfer using the secondary transfer roller 34 is performed. Then, fixing is performed using the fixing rollers 36a and 36b, and a printed image is formed on the paper. The lens 440 forms an image of light 442 reflected from the print image, and the reading sensor 74 converts the imaged light 442 into an electrical signal.

  In this configuration, each photosensitive drum 22a, 22b, 22c, 22d, each charging roller 24a, 24b, 24c, 24d, each developing roller 28a, 28b, 28c, 28d, each transfer roller 30a, 30b, 30c, 30d, and The secondary transfer roller 34 is formed in a cylindrical shape having the same radius. And it is rotated by the same drive mechanism corresponding to conveyance of a sheet | seat, and has the same rotation period. On the other hand, the intermediate transfer member 32 and the fixing rollers 36a and 36b rotate at different rotation periods.

  Paper 430, 432, 434, 436,. . . Transport timing and corresponding images 410, 412, 414, 416,. . . Is not synchronized with the rotation cycle of any of these printing rotators. Instead, the sheet conveyance interval 450 is sufficiently shortened to increase the number of sheets that can be printed per unit time.

  FIG. 3 is a diagram showing the correspondence between density unevenness (FIG. 3A) and paper (FIG. 3B) associated with the problem when there is a physical problem on the surface of the photosensitive drum 22a. . That is, the horizontal axis represents the position viewed in the transport direction. In FIG. 3A, the vertical axis expresses binary whether the density obtained as a result of the inspection is proper or inappropriate, and in FIG. 3B, the vertical axis expresses the presence / absence of the paper in binary. Yes. Referring to FIG. 3A, density unevenness 460, 461, 462,. . . Is generated at a period corresponding to one rotation of each photosensitive drum 22a. In contrast, sheets 430, 432, 434, 436,. . . Indicates the repetition period defined by the length of the sheet and its interval. For example, in the paper 430, the density unevenness 460 only appears in the vicinity of the center, but in the paper 432, the density unevenness 461 and 462 are in two places near the front end and the rear end. Appear in Therefore, it is difficult for the image quality inspection unit 150 to grasp the tendency when each of these sheets gradually changes in density.

  Next, an example in which the coincidence control unit 112 is used to cause the conveyance timing of each sheet to correspond to the photosensitive drum 22a will be described. 4 is substantially the same as FIG. 2, and the same components are denoted by the same reference numerals and description thereof is omitted. The difference from FIG. 2 is that the images 470, 472, 474,. . . Formation timing and corresponding paper 480, 482, 484,. . . Is the formation timing. That is, the conveyance timing is determined so as to correspond to the rotation cycle of the photosensitive drum 22a, and the conveyance interval 490 is larger than the conveyance interval 450 in FIG. This is due to the fact that the coincidence control unit 112 controls the image forming apparatus 10 at a conveyance timing of sending one sheet each time the photosensitive drum 22a rotates twice.

  FIG. 5 is a diagram corresponding to FIG. FIG. 5A is the same as FIG. 3A, and FIG. 5B corresponds to the control of the coincidence control unit 112 and the paper conveyance interval is longer than that in FIG. Is shown. In FIG. 5, sheets 480, 482, 484,. . . Is uneven density 460, 462, 464,. . . Appear only in one place near the center, and their positions are also consistent. Therefore, when each of these sheets gradually changes in density, the image quality inspection unit 150 can grasp the tendency.

1 is a schematic configuration diagram of an image forming system according to the present embodiment. 1 is a schematic cross-sectional view of a main part of an image forming apparatus. FIG. 6 is a diagram illustrating a correspondence example between paper and density unevenness when normal printing control is performed. 1 is a schematic cross-sectional view of a main part of an image forming apparatus. It is a figure which shows the example of a response | compatibility of the paper and density unevenness at the time of performing a coincidence control.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Image forming apparatus, 20 Printing part, 22 Photosensitive drum, 24 Charging roller, 26 Exposure part, 28 Developing roller, 30 Transfer roller, 32 Intermediate transfer body, 34 Secondary transfer roller, 36 Fixing roller, 38 Sensor, 50 Paper Conveyance path, 52 capture unit, 54 sensor, 70 inspection image data generation unit, 72 lamp, 74 reading sensor, 100 inspection / control device, 110 control unit, 112 coincidence control unit, 114 change unit, 116 normal print control unit, 118 switching unit, 120 image quality adjustment control unit, 130 storage unit, 132 image data, 134 inspection image data, 140 user setting unit, 150 image quality inspection unit.

Claims (12)

A paper transport path for transporting the paper according to the transport timing;
A printing rotator that rotates corresponding to the conveyance of the paper, and performs a printing process on the paper on the paper conveyance path using the surface of the printing rotator in accordance with the printing processing timing corresponding to the conveyance timing. A printing section to perform,
Control means for controlling the transport timing and the corresponding print processing timing;
With
The control unit is configured to transfer the transporting unit so that a corresponding part on the surface of the rotating body for printing with respect to the sheet coincides with the corresponding part with respect to a certain sheet on which printing processing has been performed. A coincidence control means for controlling timing and corresponding print processing timing;
An image forming apparatus. The image forming apparatus according to claim 1.
The control means includes
Normal print control means for improving the efficiency of print processing by controlling the transport timing and corresponding print processing timing for each sheet earlier than the transport timing and corresponding print processing timing controlled by the coincidence control means; ,
Switching means for switching between the coincidence control means and the normal printing control means;
Comprising
An image forming apparatus. The image forming apparatus according to claim 1.
The printing unit includes at least two printing rotating bodies that rotate at mutually different rotation periods,
The coincidence control means includes a changing means for changing a control target from a printing rotator having a certain rotation period to a printing rotator having another rotation period.
An image forming apparatus. The image forming apparatus according to claim 1.
The printing unit includes at least two printing rotating bodies that rotate in synchronization with each other at the same rotation period,
The coincidence control means controls the two printing rotators as control targets.
An image forming apparatus. The image forming apparatus according to claim 1.
The coincidence control means controls the conveyance timing of each sheet and the corresponding print processing timing so as to keep a rational number ratio of the conveyance period in which each sheet is conveyed with respect to the rotation period of the printing rotator. An image forming apparatus. The image forming apparatus according to claim 1.
2. The image forming apparatus according to claim 1, wherein the coincidence control unit controls all sheets conveyed one after another. The image forming apparatus according to claim 1.
Image forming, comprising: an inspection unit that performs image quality inspection using inspection image data obtained by reading a print image printed on a sheet by the printing unit with respect to a sheet having the corresponding corresponding part apparatus. A paper transport path for transporting the paper according to the transport timing;
A printing rotator that rotates corresponding to the conveyance of the paper, and performs a printing process on the paper on the paper conveyance path using the surface of the printing rotator in accordance with the printing processing timing corresponding to the conveyance timing. A printing section to perform,
A control device for controlling an image forming system comprising:
Operation information acquisition means for acquiring operation information relating to the paper transport path and the rotating body for printing from the image forming system;
Control instruction means for generating a signal for controlling the transport timing and the corresponding print processing timing based on the operation information, and transmitting the signal to the image forming system;
With
The control instruction means, for at least one sheet, so that a corresponding position on the surface of the printing rotating body for the sheet coincides with the corresponding position for a certain sheet that has been previously printed. A coincidence control instruction means for generating a control signal for conveying timing and corresponding print processing timing;
A control device characterized by that. The control device according to claim 8, wherein
The image forming system includes an inspection unit that performs an image quality inspection using inspection image data obtained by reading a print image printed on the paper by the printing unit,
The control apparatus includes an inspection instruction unit that instructs the image forming system to perform an image quality inspection by the inspection unit with respect to a sheet of which the corresponding part matches. The control device according to claim 9,
An inspection result acquisition means for acquiring a result of an image quality inspection performed based on the inspection instruction means from the image forming system;
Adjustment instruction means for instructing the image forming system to adjust print processing based on the acquired inspection result;
A control device comprising: A paper transport path for transporting the paper according to the transport timing;
A printing rotator that rotates corresponding to the conveyance of the paper, and performs a printing process on the paper on the paper conveyance path using the surface of the printing rotator in accordance with the printing processing timing corresponding to the conveyance timing. A printing section to perform,
A computer controlling an image forming system comprising:
An operation information acquisition step of acquiring operation information related to the paper conveyance path and the printing rotating body from the image forming system;
A control instruction step of generating a signal for controlling the conveyance timing and the corresponding print processing timing based on the operation information, and transmitting the signal to the image forming system;
Including
In the control instruction step, for at least one sheet, the corresponding portion on the surface of the printing rotating body with respect to the sheet matches the corresponding portion with respect to a certain sheet on which printing processing has been performed previously. Including a coincidence control instruction step for generating a control signal of the conveyance timing and the corresponding print processing timing,
A control method characterized by that. A paper transport path for transporting the paper according to the transport timing;
A printing rotator that rotates corresponding to the conveyance of the paper, and performs a printing process on the paper on the paper conveyance path using the surface of the printing rotator in accordance with the printing processing timing corresponding to the conveyance timing. A printing section to perform,
A program for controlling an image forming system comprising:
An operation information acquisition procedure for acquiring operation information relating to the paper conveyance path and the printing rotating body from the image forming system;
A control instruction procedure for generating a signal for controlling the conveyance timing and the corresponding print processing timing based on the operation information and transmitting the signal to the image forming system;
Including
The control instruction procedure is such that, for at least one sheet, the corresponding part on the surface of the printing rotating body for the sheet coincides with the corresponding part for a specific sheet on which printing processing has been performed previously. Including a coincidence control instruction procedure for generating a control signal of the transport timing and the corresponding print processing timing,
A control program characterized by that.

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