JP2012063594A - Image forming apparatus and method for controlling the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To constantly suppress a decrease in image quality due to toner density in a developing device and improve a processing throughput of a series of print jobs without temporarily interrupting an image forming process.
In an image forming apparatus, before execution of a print job, a toner density change amount due to toner consumption at the time of execution of each registered print job is predicted, and toner replenishment at the time of execution of each print job is performed. Predicting the toner density change amount, and executing each registered print job based on the detected current toner density in the developing device, a preset toner density target value, and each predicted toner density change amount After rearranging the order and notifying the user to that effect, only the first print job out of the rearranged print jobs is executed to perform image forming processing, and thereafter the same processing is repeated.
[Selection] Figure 4

Description

  The present invention relates to an electrophotographic image forming apparatus such as an electrophotographic digital copying machine, a digital multi-function peripheral (MFP), a facsimile machine, and a printer, and a control method thereof.

  The electrophotographic image forming apparatus as described above performs the following print (image forming) job. In other words, the surface of the photoreceptor, which is a rotating image carrier, is uniformly charged by a charging device, and the surface is exposed by scanning with a light beam such as a laser beam modulated according to image data emitted from the exposure device. Thus, an electrostatic latent image is formed. The electrostatic latent image is developed with toner from the developing device to be visualized as a toner image, and the toner image is transferred to a recording medium such as paper by a transfer device. Thereafter, the recording medium is passed through a fixing device to thermally fix the toner image and discharged outside the apparatus.

  By the way, as a developer accommodated in a developing device, one using a two-component developer composed of a toner and a carrier is known, and a two-component developer (hereinafter also simply referred to as “developer”) is used. When forming an image, it is necessary to maintain the toner density, which is the ratio of the toner with respect to the total amount of developer, within a predetermined range. Therefore, the toner density is detected by the toner density sensor, and the replenishment operation for replenishing the toner to the developing device is controlled so that the detected toner density becomes a predetermined target value.

  However, the amount of toner transferred from the developing device to the recording medium varies depending on complex conditions such as the pixel amount of the recording medium. Therefore, depending on the contents and order of the print job, it becomes difficult to control the toner density of the developing device, and it becomes impossible to control the toner density in the developing device to an appropriate density, and image quality may be deteriorated.

  With respect to such a problem, for example, Patent Document 1 aims to provide an image forming apparatus capable of suppressing toner consumption, a control method for the image forming apparatus, and a control program for the image forming apparatus. As a technology that can reduce image quality degradation due to toner density in the developing device and improve the processing throughput of a series of print jobs without temporarily interrupting image forming processing, Based on the amount of toner and the estimated amount of toner consumption for the next print job, if the amount of staying toner in the current developing device or the amount of staying toner after executing the print job satisfies a predetermined condition, A method for changing the job execution order is disclosed.

  However, as described in Patent Document 1, based on the current amount of staying toner in the developing device and the predicted toner consumption amount of the next print job, the amount of staying toner in the current developing device or after execution of the print job The method of changing the execution order of print jobs when the amount of staying toner satisfies a predetermined condition has the following problems (a), (b), and (c).

(A) What affects the image quality is the toner concentration, which is the ratio of the toner to the total amount of developer, and not the amount of staying toner.
(B) The amount of staying toner or the toner concentration varies depending on the toner replenishment performed during execution of the print job, but this is not taken into consideration.
(C) Even when a plurality of print jobs are registered, the execution order of the print jobs is changed without considering only the staying toner amount state up to the print job one step ahead, It does not take into account the results of job execution.

  That is, for the next print job, it is guaranteed that the toner density falls within the predetermined range, but when all of the registered print jobs are executed, the toner density is predetermined during or after that. Since it is not guaranteed whether it is within the range and the response will be followed, it may not be possible to suppress deterioration in image quality due to toner density in the developing device, and a series of operations without temporarily interrupting image formation processing There has been a problem that the processing throughput of the print job cannot be improved.

  The present invention has been made in view of the above points, and always suppresses a decrease in image quality due to toner density in the developing device, and processing throughput of a series of print jobs without temporarily interrupting image forming processing. It aims at improving.

In order to achieve the above object, the present invention provides the following image forming apparatus and control method thereof.
An image forming apparatus according to the present invention includes a developing device that develops an electrostatic latent image formed on an image carrier with toner, a toner concentration detecting unit that detects a toner concentration in the developing device, and a plurality of image forming devices. An image forming apparatus having an image forming job holding unit for holding a job, wherein the toner density change due to toner consumption at the time of execution of each image forming job held by the image forming job holding unit before executing the image forming job A first prediction unit that predicts the amount, and a second prediction that predicts a toner density change amount due to toner replenishment at the time of execution of each image forming job held by the image forming job holding unit before executing the image forming job. And a current toner density detected by the toner density detecting means, a preset toner density target value, The execution order of the image forming jobs held by the image forming job holding unit is arranged based on the toner density change amount predicted by the second predicting unit and the toner density change amount predicted by the second predicting unit. A rearranging means for changing and an image forming processing means for performing an image forming process based on each of the image forming jobs rearranged thereby are provided.

Furthermore, you may make it show in either of the following (1)-(4).
(1) The image forming processing unit sequentially executes all the image forming jobs rearranged by the rearranging unit to perform image forming processing.
(2) The image forming processing means is a means for executing image forming processing by executing only the first print job among the image forming jobs rearranged by the rearranging means, and the first predicting means. After the execution of only the first print job by the image forming processing means, and before the execution of the next image forming job, the toner at the time of execution of the remaining image forming jobs held by the image forming job holding means The second predicting unit is configured to predict the toner density change amount due to consumption, and after the first print job is executed only by the image forming processing unit, the remaining image forming job is executed before the next image forming job is executed. Means for predicting the amount of toner density change due to toner replenishment at the time of execution of each image forming job, and the rearranging means are controlled by the image forming processing means. After only the first print job is executed before the next image forming job execution, sort also arranges the execution order of said each remaining image forming job.

(3) The image forming processing means is a means for executing image forming processing by executing a predetermined number of print jobs from the beginning among the image forming jobs rearranged by the rearranging means, and After the predetermined number of print jobs are executed by the image forming processing means from the beginning, the remaining image formation held by the image forming job holding means is executed before the next image forming job is executed. A means for predicting a toner density change amount due to toner consumption at the time of execution of a job is used, and the second prediction means is used for the next image after a predetermined number of print jobs have been executed from the beginning by the image forming processing means. Prior to execution of the forming job, means for predicting a toner density change amount due to toner replenishment at the time of execution of each of the remaining image forming jobs is provided. After the print job of the predetermined number from the beginning it is executed by forming the processing means, prior to the next image forming job execution, sort also arranges the execution order of said each remaining image forming job.

(4) A new image forming job is additionally held in the image forming job holding unit while the first predicting unit is executing the image forming job rearranged by the rearranging unit. In this case, before executing the next image forming job, the second image forming unit is also configured to predict a toner density change amount due to toner consumption when executing the remaining image forming jobs held by the image forming job holding unit. When a new image forming job is additionally held in the image forming job holding unit while the image forming processing unit executes each image forming job rearranged by the rearranging unit, the predicting unit performs the next image. Before execution of the forming job, the image forming apparatus is configured to predict a toner density change amount due to toner replenishment when each of the remaining image forming jobs is executed. When a new image forming job is additionally held in the image forming job holding means while the image forming job is being executed by the image forming job sorted by the sorting means, before the next image forming job is executed, The execution order of the remaining image forming jobs is rearranged.

  Further, as a result of the rearrangement by the rearrangement unit, when there is an image formation job whose toner density does not fall within the preset allowable range, an image formation job division unit for dividing the image formation job is provided. The first predicting means includes means for predicting a toner density change amount due to toner consumption at the time of execution of each image forming job for each image forming job divided by the image forming job dividing means. The second predicting means includes means for predicting a toner density change amount due to toner replenishment at the time of execution of each image forming job for each image forming job divided by the image forming job dividing means. The toner density change amount is predicted by the first and second predicting means for each image forming job divided by the image forming job dividing means. After being it may also be subjected to the sort.

Furthermore, notification means for notifying the user of the result of rearrangement by the rearrangement means may be provided.
Moreover, you may provide the selection means to select whether to perform the rearrangement by the said rearrangement means. In this case, the selection means may select according to an instruction from the outside.

  A control method according to the present invention includes a developing device that develops an electrostatic latent image formed on an image carrier with toner, a toner concentration detection unit that detects a toner concentration in the developing device, and a plurality of image forming jobs. A control method for an image forming apparatus having an image forming job holding unit that holds toner, wherein toner is consumed by toner consumption when each image forming job held by the image forming job holding unit is executed before the image forming job is executed. A first predicting step for predicting a density change amount, and a second for predicting a toner density change amount due to toner replenishment at the time of execution of each image forming job held by the image forming job holding unit before executing the image forming job. Prediction process, and the current toner density detected by the toner density detection means before the execution of the image forming job. Each image forming job held by the image forming job holding unit based on the value, the toner density change amount predicted by the first prediction step, and the toner density change amount predicted by the second prediction step A rearrangement step for rearranging the execution order of the first and second image formation processing steps, and an image formation processing step for performing image formation processing based on the image formation jobs rearranged thereby.

  According to the present invention, before execution of an image forming job, a toner density change amount due to toner consumption at the time of execution of each held image forming job is predicted, and toner by toner replenishment at the time of execution of each image forming job is used. The execution order of each held image forming job based on the detected current toner density in the developing device, the preset toner density target value, and the predicted toner density change amount The image forming process is performed based on the rearranged image forming jobs, so that the deterioration of the image quality due to the toner density in the developing device is always suppressed, and the image forming process is not temporarily interrupted. The processing throughput of a series of image forming jobs can be improved.

1 is a block diagram illustrating an example of a system configuration of an image processing system of an MFP according to the present invention. FIG. 2 is a diagram illustrating a schematic configuration example of a mechanism unit of a color printer including the image forming unit of FIG. FIG. 3 is a diagram illustrating a configuration of a toner replenishing device that replenishes toner from a toner cartridge 230 to the developing device 221 of FIG. 2. FIG. 2 is a flowchart showing an example of print job rearrangement processing before execution of a print job by the system controller 106 in the ACP 100 and the process controller 203 in the color printer 200 in FIG. 1.

Hereinafter, embodiments for carrying out the present invention will be specifically described with reference to the drawings.
The following embodiments have the following characteristics when processing a print (image forming) job. In other words, the amount of toner density change due to toner consumption when a toner image is transferred to a recording medium (when executing a print job) and the replenishment of toner when the print job is executed before each print job is executed. The amount of toner density change due to each is predicted, and the order of execution of all print jobs is rearranged so that the toner density difference from the toner density target value is the smallest, and scheduling is performed sequentially from the first print job of the rearranged result It is characterized by executing and rescheduling as appropriate.

Therefore, the feature will be described in detail.
First, a system configuration of an image processing system of a digital multifunction peripheral (hereinafter referred to as “MFP”) copier according to the present invention will be described.
FIG. 1 is a block diagram showing a system configuration example of an image processing system of the MFP.
In this MFP system, a color document scanner 10 including a reading unit 11 and an image data output interface (hereinafter, “interface” is also referred to as “I / F”) 12 is included in an image data processing apparatus (hereinafter, referred to as “ACP”) 100. An image data I / F control unit (hereinafter referred to as “CDIC”) 101 is connected.

A color printer 200 is also connected to the ACP 100.
The color printer 200 receives the recorded image data from the image data processor (hereinafter referred to simply as “IPP”) 102 of the ACP 100 to the writing I / F 201, and uses the image forming unit 202 (to be described later) Printout (printing) to the transfer material).

  The ACP 100 includes a parallel bus Pb, a local bus Rb, a CDIC 101, an IPP 102, a memory access control unit (hereinafter referred to as “IMAC”) 103, a memory module that is an image memory (hereinafter referred to as “MEM”) 104, and a hard disk device that is a nonvolatile memory. (Hereinafter referred to as “HDD”) 105, system controller 106, RAM 107, nonvolatile memory 108, font ROM 109, parallel bus I / F 110, serial bus I / F 111, local bus I / F 112, network I / F 113, and external serial A port board 114 is provided.

A facsimile control unit (hereinafter simply referred to as “FCU”) 500 is connected to the parallel bus Pb.
The operation board 20 is connected to the system controller 106. The operation board 20 includes an operation panel having various operation keys and a display for inputting an operation request (instruction) to the image forming unit 202 or the like by a user operation.

  A reading unit 11 that optically reads an original image of the color original scanner 10 photoelectrically converts reflected light of lamp irradiation on the image surface of the original by a CCD on a sensor board unit (hereinafter simply referred to as “SBU”) 13. R, G, B image signals are generated, converted to RGB image data by an A / D converter, then subjected to shading correction, and sent to the CDIC 101 via the output I / F 12. The RGB image data is multi-value image data (for example, 8-bit configuration) representing multi-gradation having a configuration of 3 bits or more.

The CDIC 101 relates to image data, and transfers data between the output I / F 12 of the color document scanner 10, the parallel bus Pb, and the IPP 102, and communication between the process controller 203 of the color printer 200 and the system controller 106 that controls the ACP 100. Control.
A RAM 204 of the color printer 200 is used as a work area of a process controller 203 composed of a CPU (microprocessor), and a ROM 205 stores an operation program of the process controller 203 and the like.

The IMAC 103 controls writing / reading of image data and control data with respect to the MEM 104 and the HDD 105.
The system controller 106 controls the operation of each component connected to the parallel bus Pb.
A RAM 107 is used as a work area of a system controller 106 composed of a CPU, a nonvolatile memory 108 stores an operation program of the system controller 106, and a font ROM 109 stores font data.

The operation board 20 instructs processing to be performed by the ACP 100. For example, the processing type (copying, facsimile transmission, image reading, printing, etc.), the number of processings, and the like are input. Thereby, the image data control information can be input.
The image data read from the reading unit 11 of the scanner 10 is subjected to shading correction by the SBU 13 of the scanner 10 and then subjected to image processing for correcting reading distortion such as noise line removal, background removal, scanner gamma correction, and filter processing by the IPP 102. And stored in the MEM 104 or the HDD 105.

  When printing out the image data in the MEM 104 or the HDD 105, the IPP 102 converts the RGB image data into YMCK image data, and performs image quality such as printer gamma conversion, gradation conversion, and gradation processing such as dither processing or error diffusion processing. Process. The image data after the image quality processing is transferred from the IPP 102 to the writing I / F 201 of the color printer 200. The writing I / F 201 performs laser control with respect to image data subjected to gradation processing by pulse width and power modulation. Thereafter, the image data is sent to the image forming unit 202, and the image forming unit 202 forms a reproduced image on a sheet.

The IMAC 103 of the ACP 100 is based on the control of the system controller 106, access control of the image data and the MEM 104 or the HDD 105, and a LAN (local area network).
) Expansion of print data from personal computers (hereinafter abbreviated as “PC”) 601 and 602 connected on 600, and compression / decompression of image data for effective use of the MEM 104 and the HDD 105.

  The image data sent to the IMAC 103 is stored in the MEM 104 or the HDD 105 after data compression, and the stored image data is read out as necessary. The read image data is expanded, returned to the original image data, and returned from the IMAC 103 to the CDIC 101 via the parallel bus I / F 110 and the parallel bus Pb. After transfer from the CDIC 101 to the IPP 102, image quality processing is performed and output to the writing I / F 201, and a reproduced image is formed on the paper in the image forming unit 202.

In the flow of image data, the functions of the digital multifunction peripheral (MFP) are realized by the bus control by the parallel bus Pb and the CDIC 101.
Facsimile transmission is performed by performing image processing (image quality processing) on the read image data in the IPP 102 and transferring it to the FCU 500 via the CDIC 101 and the parallel bus Pb.

  The FCU 500 converts the transferred image data to a communication network, and transmits it to the public line (PN) 501 as facsimile data. Facsimile reception is performed by converting line data from the public line 501 into image data by the FCU 500 and transferring it to the IPP 102 via the parallel bus Pb and the CDIC 101. In this case, no special image quality processing is performed and the image is output to the writing I / F 201 and a reproduced image is formed on the paper in the image forming unit 202.

In the situation where a plurality of jobs (including print jobs), for example, a copy function, a facsimile transmission / reception function, and a printer output function operate in parallel, the usage rights of the reading unit 11, the image forming unit 202, and the parallel bus Pb are allocated to the jobs. Are controlled by the system controller 106 and the process controller 203. The requested job (request data) is stored and registered (registered) in the RAM 107.
The process controller 203 controls the flow of image data, and the system controller 106 controls the entire system and manages the activation of each resource. Further, the function selection of the MFP is performed on the operation board 20, and processing contents such as a copy function and a facsimile function are set by the selection input of the operation board 20.

  The system controller 106 and the process controller 203 communicate with each other via the parallel bus Pb, the CDIC 101, and the serial bus Sb. Specifically, in the CDIC 101, communication between the system controller 106 and the process controller 203 is performed by performing data format conversion for data and interface between the parallel bus Pb and the serial bus Sb.

Various bus interfaces such as a parallel bus I / F 110, a serial bus I / F 111, a local bus I / F 112, and a network I / F 113 are connected to the IMAC 103.
In order to maintain independence in the entire ACP 100, the system controller 106 is connected to related units via a plurality of types of buses.

  The system controller 106 controls other functional units via the parallel bus Pb. The parallel bus Pb is used for transferring image data. The system controller 106 issues an operation control command for storing image data in the MEM 104 or the HDD 105 to the IMAC 103. This operation control command is sent via the IMAC 103, the parallel bus I / F 110, and the parallel bus Pb. In response to this operation control command, the image data is sent from the CDIC 101 to the IMAC 103 via the parallel bus Pb and the parallel bus I / F 110. The image data is stored in the MEM 104 or the HDD 105 under the control of the IMAC 103.

On the other hand, the system controller 106 of the ACP 100 functions as a printer controller, network control, and serial bus control when calling from the PC 601 or 602 as a printer function.
In the case of via the network (wide area communication network) 700, the IMAC 103 receives print output request data (print job) or storage (storage) request data via the network 700 via the network I / F 113. Request data (foreign command) via the network 700 is notified to the system controller 106, and the IMAC 103 transfers or receives and accumulates the accumulated data via the network 700 in accordance with a command from the system controller 106 in response thereto.

In the case of a general-purpose serial bus connection, the IMAC 103 receives print output request data via the serial bus I / F 111. The general-purpose serial bus I / F 111 corresponds to a plurality of types of standards, and corresponds to an interface of a standard such as USB (Universal Serial Bus) 1284 or 1394, for example.
Print output request data from the PC 601 or 602 is stored and held in the RAM 107 by the system controller 106, and is developed into image data when a print job is started. The development destination is an area in the MEM 104. Font data necessary for expansion is obtained by referring to the font ROM 109 via the local bus I / F 112 and the local bus Rb. The local bus Rb connects the system controller 106 to the nonvolatile memory 108 and the RAM 107.

Regarding the serial bus Sb, in addition to the external serial port board 114 for connection to the PC 601 or 602, there is also an interface for transfer to the operation board 20 which is the operation unit of the ACP 100. This communicates with the system controller 106 via the IMAC 103 instead of the print development data, accepts processing procedures, displays the system status, and the like.
Data transmission / reception between the system controller 106, the MEM 104, the HDD 105, and various buses is performed via the IMAC 103. Jobs using the MEM 104 and the HDD 105 are centrally managed in the entire ACP 100.

  Here, the system controller 106 in the ACP 100 and the process controller 203 of the color printer 200 execute corresponding operation programs to control the image forming unit 202 and the like in the color printer. Functions of the second prediction unit, rearrangement unit, image formation processing unit, image formation job division unit, notification unit, and selection unit can be achieved.

Next, an outline of the configuration of the mechanism unit of the color printer 200 including the image forming unit 202 of FIG. 1 will be described.
FIG. 2 is a diagram illustrating a schematic configuration example of a mechanism unit of the color printer 200.
The color printer 200 constitutes an MFP by being connected to the color original scanner 10 shown in FIG.
This color printer 200 is an indirect transfer type tandem color printer, and as shown in FIG. 2, K (black), M (magenta), C (cyan), Y constituting the image forming unit 202 of FIG. Each photosensitive unit 212 (212K, 212M, 212C, 212Y) that performs image formation of each color of (yellow) is provided.

Further, an intermediate transfer member 213 made of an endless belt is disposed facing each photoconductor unit 212, and the intermediate transfer member 213 is wound around a plurality of support rollers and travels in the direction indicated by an arrow A.
Further, by the image forming unit 202 including each photoconductor unit 212, each of the photoconductors 220 (220K, 220M, 220C, 220Y), which is an image carrier, based on a known electrophotographic method, respectively, A toner image, a C toner image, and a Y toner image are formed.

  That is, the surface of each photoconductor 220 is uniformly charged by each charging device, and the surface of each photoconductor 220 is a light beam such as each laser beam modulated according to image data emitted from the exposure device. An electrostatic latent image is formed by exposure by scanning. Each electrostatic latent image is developed with toner from each developing device (developer) 221 (221K, 221M, 221C, 221Y) to be visualized as a toner image, and these toner images are intermediately transferred. The images are electrostatically transferred by being sequentially stacked on the body 213. Here, the order of image formation is the order of K, M, C, and Y. However, the order is not limited to this, and the characteristics of the toner and the finishing effect of the color image finally formed on the paper It may be determined according to.

  A sheet feeding device 214 is disposed in the lower part of the color printer 200, and a sheet (transfer material) sent out from the sheet feeding device 214 is conveyed along a conveying path, and is transferred to an intermediate transfer member 213 via a registration roller 215. And the transfer device 216. When the sheet passes between the intermediate transfer member 213 and the transfer device (transfer roller) 216, the toner images superimposed on the intermediate transfer member 213 are transferred onto the sheet. Next, the sheet passes through the fixing device 217, and at this time, the image on the sheet is fixed to the sheet by the action of heat and pressure. The sheet that has passed through the fixing device 217 is discharged to the discharge unit 218.

A set unit 219 to which four toner cartridges 230 (230K, 230M, 230C, 230Y) are mounted is provided between the discharge unit 218 and the intermediate transfer member 213 of the color printer 200.
Each toner cartridge 230 includes a toner bottle (toner container) containing toner to be supplied to the developing device 221 (221K, 221M, 221C, 221Y) of each photoconductor unit 212, and is detachably attached to the set unit 219. Is done.

FIG. 3 is a diagram illustrating a configuration of a toner supply device that supplies toner from the toner cartridge 230 to the developing device 221 of FIG. This toner replenishing device is actually provided for each developing device 221 of each color.
In FIG. 3, a toner image is formed on the photosensitive member 220 of FIG. 2 by the developing device 221 of the color printer 200 by a known electrophotographic method. The developing device 221 includes a powder pump 300, and the toner in the toner cartridge 230 is replenished into the developing container 221a through a tube 305 that is a toner transfer member by the operation of the powder pump 300. The tube 305 communicates with the inside of the toner cartridge 230 through the nozzle 231.

  The powder pump 300 uses a suction type uniaxial eccentric powder pump (commonly known as “Mono pump”) or the like. The structure is composed of a rotor 301 formed in a screw shape eccentric with a material having rigidity such as metal, a stator 302 in which two screw-shaped holes are formed by rubber material and fixedly installed, and these are wrapped and powdered. The housing 303 is formed of a resin material or the like that forms a body transfer path. Due to the rotation of the rotor 301, a strong self-priming force (suction pressure) is generated in the pump, and the toner can be sucked from the toner cartridge 230.

  The tube 305 is a tube having an inner diameter of 4 to 10 mm, and is made of a flexible rubber material (ex polyurethane, nitrile, EPDM, silicon, etc.) and a plastic material (polyethylene, nylon, etc.) excellent in toner resistance. It is valid. The sucked toner falls into the developing container 221a from the toner introduction hole 222 provided in a part of the developing device 221, and is further transferred to the developing unit by a stirring screw (not shown). When the two-component development method is used, the toner (sucked toner) replenished during this transfer process is agitated and mixed with the developer in the developing container 221a, so that the uniform agent concentration and an appropriate charge amount are obtained.

  The toner cartridge 230 requires that the toner is always present in the vicinity of the toner suction portion 232 indicated by hatching in order to suck and convey the toner by the powder pump 300. Some containers have a spiral projection on the inner wall of the container and convey toner to the tip of the container by rotation of the cartridge body.

  In such a toner replenishing device, the mixing ratio of the toner and the carrier in the developing container 221a is based on a magnetic permeability detector (toner concentration sensor) corresponding to a toner concentration detecting means (not shown) provided in a part of the developing device 221. When the change is detected and it is detected that the toner amount is small, the drive shaft 304 of the powder pump 300 is driven to rotate, the powder pump 300 is operated, and the powder pump 300 is transferred into the developing container 221a. When the toner reaches a certain amount or more, the driving can be interrupted by the output signal of the magnetic permeability detector and the operation of the powder pump 300 can be stopped.

Next, print job rearrangement (hereinafter also referred to as “scheduling”) processing prior to print job execution by the system controller 106 in the ACP 100 and the process controller 203 in the color printer 200 in FIG. 1 will be described. This scheduling process is actually performed for each toner color (each developing device). For convenience of explanation, a process corresponding to one toner color will be described.
FIG. 4 is a flowchart showing an example of the scheduling process before execution of the print job.

  When the start of the print job is requested, the system controller 106 first proceeds to step S1 to determine whether or not to rearrange (schedule) the print jobs. If not, the system controller 106 proceeds to step S11. Proceed to S2. The selection of whether or not to rearrange print jobs is performed by, for example, a command (external) issued when the user performs a predetermined operation on the print screen on the operation board 20 (operation panel) or the PC 601 or 602. (Instructions from This processing function corresponds to a function as a selection unit according to the present invention.

In step S11, the print jobs are executed in the order of registration for all the registered print jobs (hereinafter also simply referred to as “jobs”), and the processing in FIG. 4 ends.
In step S <b> 2, for each registered print job, the process controller 203 predicts a toner density change amount due to toner consumption at the time of job execution. A specific method for predicting the toner density change amount will be described in detail later. The processing function in step S2 corresponds to a function as a first prediction unit according to the present invention.
In the next step S3, for each registered print job, the process controller 203 predicts the toner density change amount due to toner supply at the time of job execution. A specific method for predicting the toner density change amount will be described in detail later. The processing function in step S3 corresponds to a function as a second prediction unit according to the present invention.

In the next step S4, the current toner density in the developing device detected by the magnetic permeability detector (toner density sensor), a preset toner density target value (stored in the HDD 105 or the non-volatile memory 108 in FIG. 1). Based on the toner density change amounts predicted in steps S2 and S3, the execution order of all print jobs is rearranged and scheduling is performed. A specific scheduling method will also be described in detail later. The processing function in step S4 corresponds to a function as a rearranging unit according to the present invention.
In the next step S5, whether or not there is a job whose toner density does not fall within the allowable range as a result of rearranging the execution order of the print jobs in step S4 (whether toner density control is likely to be difficult during job execution). Determine.

If the result of the determination is that there is a print job in which the toner density does not fall within the allowable range (the toner density control is likely to be difficult during job execution), the process proceeds to step S6. If there is no print job whose toner density does not fall within the allowable range (it is unlikely that toner density control will be difficult during job execution), the process proceeds to step S8.
Here, within the allowable range, an upper limit value and a lower limit value of the difference between the toner density and the toner density target value are set, for example, as a toner density target value ± 0.1V.

  In step S6, the print job is divided so that the toner density falls within the allowable range with respect to the print job whose toner density does not fall within the allowable range. Further, for each of the divided print jobs, the process controller 203 predicts each toner density change amount similarly to steps S2 and S3. For example, by dividing the print job into two print jobs, it can be expected that each print job falls within an allowable range. The processing function in step S6 corresponds to the functions as the image forming job dividing unit and the first and second predicting units according to the present invention.

In the next step S7, the execution order of all print jobs is rearranged again based on the toner density change amounts predicted in steps S2, S3, and S6, and scheduling is performed. This processing function corresponds to the function as the rearranging means according to the present invention, like the processing function in step S4.
In the next step S8, the user is notified that the print jobs have been rearranged in step S4 or S7. For example, the user is notified by displaying on the display on the operation board 114 that the print jobs have been rearranged, or transmitted to an external device such as the PC 601 or 602 and displayed on the display to the user. You can be notified. This processing function corresponds to a function as notification means according to the present invention.

  In the next step S9, the process controller 203 executes only the first print job as a result of rearranging the print jobs in step S4 or S7, and performs printing (image forming processing) using the image forming unit 202. . In this example, only the first job is executed, but all jobs may be executed at once, a predetermined number of jobs may be executed at once, or a new job is added. May be executed. The processing function in step S9 corresponds to a function as an image forming processing unit according to the present invention.

  In the next step S10, it is checked whether or not there is a next print job (unexecuted print job). If there is a next print job, the process returns to step S2 and the same processing is performed again. However, for each remaining print job registered, in step S2, a toner density change amount due to toner consumption at the time of job execution is predicted, and in step S3, a toner density change amount due to toner supply at the time of job execution is predicted. If there is no next print job, the processing in FIG. 4 is terminated. Even when a new print job is added during the process of step S9, it is determined in step S10 that there is a next print job, and the process returns to step S2.

As described above, only the first print job is executed (or a predetermined number of print jobs are executed at once), and the process returns to step S2 to perform scheduling again, so that after the first job execution (or the predetermined number of job executions) Even if the toner density of (after) greatly differs from the predicted value, it can be corrected immediately at the next job execution.
After that, if it is determined in step S10 that there is no next print job, all print jobs have been executed, and the processing in FIG. 4 is terminated.

Next, a method for predicting a toner density change amount due to toner consumption at the time of execution of a print job in step S2 in FIG. 4 will be specifically described.
Table 1 is an explanatory diagram for specifically explaining a method of predicting a toner density change amount due to toner consumption at the time of execution of the print job.

For example, a function table is prepared in which a change in toner density per sheet is associated with each sheet that can be specified and its size and orientation.
Here, in order to simplify the description, it is assumed that there is no difference in the toner density change amount for each toner color, but a function table may be prepared for each toner color.
The function table used here is represented by, for example, a function using “pixel amount” as a parameter (“f11 to f24” in this example).

From this function table, a toner density change amount due to toner consumption at the time of execution of a print job is predicted.
For example, assuming that the content of a print job is plain paper, A4 portrait, N sheets, and a black K pixel amount A11, the toner density change amount V11 due to black K toner consumption at the time of job execution is as follows. Can be predicted by the formula.
V11 = B11 × N = f1 (A11) × N

Next, a method for predicting a toner density change amount due to toner replenishment at the time of execution of a print job in step S3 in FIG. 4 will be specifically described.
Table 2 is an explanatory diagram for specifically explaining a method for predicting a toner density change amount due to toner replenishment at the time of execution of the print job.

For example, a function table is prepared in which a change in toner density per print job is associated with each specifiable paper and its size and orientation.
Here, for the sake of simplicity, it is assumed that there is no difference in toner density change amount for each toner color, but a function table may be prepared for each toner color.
The function table used here is represented by a function (“g11 to g24” in this example) using, for example, the toner density before the job execution, the toner density target value, and the number of printed sheets as parameters.

From this function table, the amount of change in toner density due to toner replenishment when a print job is executed is predicted.
For example, assuming that the content of the print job JOB1 is plain paper, A4 portrait, N1 sheets, toner density C11 before execution of a black K job, and toner density target value D11, black K toner at the time of job execution at this time The toner density change amount W11 due to replenishment can be predicted by the following equation.
W11 = g1 (C11, D11, N1)

Next, the scheduling method of the print job execution order in step S4 in FIG. 4 will be specifically described.
Table 3 is an explanatory diagram for specifically explaining the print job execution order scheduling method.

  The total number of print jobs is n, and a set of the toner density target value and the toner density change amount of the print job k (k = 1,... N) is expressed by Formula 1 for each toner color (that is, for each developing device 221). It is related. Here, referring to Tables 1 and 2 for the toner density change amount.

  A set of the toner density target value and the toner density change amount of the kth (k = 1,... N) print job from the beginning of the rearranged result has the relationship shown in Formula 2 for each toner color.

  Further, the current toner density detected by the magnetic permeability detector (hereinafter simply referred to as “current toner density”) is represented by Equation 3 for each toner color.

  At this time, the difference between the toner density target value before execution of the first print job as a result of the rearrangement and the current toner density has the relationship shown in Formula 4 for each toner color.

  Further, the difference between the toner density target value after execution of the print job and the current toner density has the relationship shown in Formula 5 for each toner color.

  Similarly, the difference between the toner density target value before execution of the k (k = 2,..., N) -th print job and the current toner density as a result of the rearrangement is as shown in Equation 6 for each toner color. Become.

  Further, the difference between the toner density target value after execution of the print job and the current toner density has the relationship shown in Equation 7 for each toner color.

  When all of these are added for each toner color, the relationship shown in Equation 8 is obtained.

For example, the print jobs are rearranged so that the value for each toner color is minimized on average, that is, the value obtained by adding all the four expressions of Equation 8 is minimized.
Here, for the sake of simplicity, the same weight is assigned to each toner color. However, a value obtained by adding a weight to each toner color may be minimized, or may be minimized only for a specific toner color. It may be made to become.
Thus, scheduling can be performed by rearranging the execution order of all print jobs so that the toner density difference from the toner density target value is the smallest.

  Thus, before executing a print job, the toner density change amount due to toner consumption at the time of execution of each registered print job is predicted, and the toner density change amount due to toner supply at the time of execution of each print job is estimated. Based on the predicted and detected current toner density in the developing device, a preset toner density target value, and each predicted toner density change amount, the execution order of each registered print job is rearranged, By performing image formation processing based on each of the rearranged print jobs, a series of print job processing can be performed without suppressing image quality degradation due to toner density in the developing device at all times and without temporarily interrupting image formation processing. Throughput can be improved.

  As described above, the present invention is applied to an indirect transfer type MFP in which a toner image of each color is sequentially transferred and transferred onto an intermediate transfer member from the photosensitive member of each photosensitive unit, and then the full color toner image is collectively transferred to a transfer material. However, the present invention is not limited to this, and various image forming apparatuses such as an indirect transfer type digital copying machine, a facsimile machine, and a printer, of course, transfer from the photoreceptor of each photoreceptor unit. The present invention can also be applied to various image forming apparatuses of a direct transfer system that directly transfer toner images of respective colors onto a material. Alternatively, the present invention can also be applied to a monochromatic image forming apparatus such as monochrome, or an image forming apparatus having two or three colors.

  The present invention can be used in various image forming apparatuses such as a copying machine, a printer, a facsimile machine, and a digital multi-function peripheral (MFP), such as electrophotographic single color to full color.

20: Operation board 100: ACP 106: System controller 107, 204: RAM 108: Non-volatile memory 200: Color printer 202: Image forming unit 203: Process controller 205: ROM
212: Photoconductor unit 220: Photoconductor 221: Developing device 221a: Developing container 230: Toner cartridge 300: Powder pump 301: Rotor 601 and 602: PC

JP 2009-282447 A

Claims (10)

A developing device that develops an electrostatic latent image formed on an image carrier with toner, a toner density detecting unit that detects a toner density in the developing device, and an image forming job holding that holds a plurality of image forming jobs An image forming apparatus comprising:
A first predicting unit that predicts a toner density change amount due to toner consumption at the time of execution of each image forming job held by the image forming job holding unit before executing an image forming job;
A second predicting unit that predicts a toner density change amount due to toner replenishment at the time of execution of each image forming job held by the image forming job holding unit before executing an image forming job;
Prior to execution of the image forming job, the current toner density detected by the toner density detecting means, a preset toner density target value, the toner density change amount predicted by the first predicting means, and the second Reordering means for reordering the execution order of each image forming job held by the image forming job holding means based on the toner density change amount predicted by the predicting means;
An image forming apparatus comprising: an image forming processing unit configured to perform an image forming process based on each image forming job rearranged by the rearranging unit.   The image forming apparatus according to claim 1, wherein the image forming processing unit performs image forming processing by sequentially executing all the image forming jobs rearranged by the rearranging unit. The image forming processing means is a means for executing image forming processing by executing only the first print job among the image forming jobs rearranged by the rearranging means,
The first predicting unit performs the remaining image formation held by the image forming job holding unit after the image forming processing unit executes only the first print job and before executing the next image forming job. It is also a means to predict the amount of toner density change due to toner consumption during job execution.
The second predicting unit is configured to perform toner supply by toner supply at the time of executing each of the remaining image forming jobs after the image forming processing unit executes only the first print job and before executing the next image forming job. It is a means to predict the amount of concentration change,
The rearranging unit rearranges the execution order of the remaining image forming jobs after the image forming processing unit executes only the first print job and before executing the next image forming job. The image forming apparatus according to claim 1. The image forming processing means is a means for executing image forming processing by executing a predetermined number of print jobs from the beginning among the image forming jobs rearranged by the rearranging means,
The first predicting unit performs the remaining number of images held by the image forming job holding unit after the predetermined number of print jobs are executed by the image forming processing unit and before the next image forming job is executed. A means for predicting a change in toner density due to toner consumption during execution of each image forming job,
The second predicting unit is configured to execute toner for each remaining image forming job after the predetermined number of print jobs are executed by the image forming processing unit and before execution of the next image forming job. It is a means to predict the amount of toner density change due to replenishment,
The rearranging unit rearranges the execution order of the remaining image forming jobs after the predetermined number of print jobs are executed by the image forming processing unit and before the next image forming job is executed. The image forming apparatus according to claim 1. The first predicting unit is provided when a new image forming job is additionally held in the image forming job holding unit while the image forming processing unit executes each image forming job rearranged by the rearranging unit. A means for predicting a toner density change amount due to toner consumption at the time of execution of each of the remaining image forming jobs held by the image forming job holding means before execution of the next image forming job;
The second predicting means is provided when a new image forming job is additionally held in the image forming job holding means while the image forming processing means executes each image forming job rearranged by the rearranging means. And a means for predicting a toner density change amount due to toner replenishment at the time of executing each of the remaining image forming jobs before the next image forming job is executed,
The rearranging unit is configured to perform the following operation when a new image forming job is additionally held in the image forming job holding unit while the image forming processing unit executes each image forming job rearranged by the rearranging unit. The image forming apparatus according to claim 1, wherein the execution order of the remaining image forming jobs is also rearranged before the execution of the image forming job. The image forming apparatus according to any one of claims 1 to 5,
An image forming job dividing unit for dividing the image forming job when there is an image forming job whose toner density does not fall within a preset allowable range as a result of the rearranging by the rearranging unit;
The first predicting means includes means for predicting a toner density change amount due to toner consumption at the time of execution of each image forming job for each image forming job divided by the image forming job dividing means,
The second predicting means has means for predicting a toner density change amount due to toner replenishment at the time of execution of each image forming job for each image forming job divided by the image forming job dividing means,
The rearranger performs the rearrangement even after the toner density change amount is predicted by the first and second predictors for each image forming job divided by the image forming job divider. An image forming apparatus. The image forming apparatus according to any one of claims 1 to 6,
An image forming apparatus comprising notification means for notifying a user of a result of sorting by the sorting means. The image forming apparatus according to any one of claims 1 to 7,
An image forming apparatus comprising: a selection unit that selects whether or not to perform rearrangement by the rearrangement unit.   The image forming apparatus according to claim 8, wherein the selection unit performs selection according to an instruction from the outside. A developing device that develops an electrostatic latent image formed on an image carrier with toner, a toner density detecting unit that detects a toner density in the developing device, and an image forming job holding that holds a plurality of image forming jobs A control method in an image forming apparatus having
A first prediction step of predicting a toner density change amount due to toner consumption at the time of execution of each image forming job held by the image forming job holding unit before executing the image forming job;
A second prediction step of predicting a toner density change amount due to toner replenishment at the time of execution of each image forming job held by the image forming job holding unit before executing the image forming job;
Prior to execution of the image forming job, the current toner density detected by the toner density detector, a preset toner density target value, the toner density change amount predicted by the first prediction process, and the second A rearrangement step of rearranging the execution order of the image forming jobs held by the image forming job holding unit based on the toner density change amount predicted by the prediction step;
A control method comprising: an image forming process step of performing an image forming process based on each image forming job rearranged by the rearranging step.

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