JP2018097139A - Image formation system and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image formation system and program which can perform the gradation expression intended by a user without restricting the total amount of toner that can be printed.SOLUTION: An image formation system in which a plurality of image formation apparatuses are arranged in series includes: determination means which determines whether or not a toner amount per one pixel in at least a partial image exceeds a prescribed threshold in a case where the image based on the image data is formed with respect to the acquired image data; division means which generates divided image data by dividing the image data for which the determination means determines that the toner amount per one pixel in at least the partial image exceeds the prescribed threshold so that the toner amount per one pixel does not exceed the prescribed threshold; and control means which performs control so that image formation of the divided image data divided by the division means is shared by the plurality of image formation apparatuses.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an image forming system and a program.

  2. Description of the Related Art Conventionally, an image forming system configured by connecting a plurality of (for example, two) image forming apparatuses in series along a sheet conveyance direction is known (for example, see Patent Document 1). According to this image forming system, in the case of double-sided printing, for example, the back side of the sheet is printed by the first image forming apparatus positioned upstream in the sheet conveying direction, and the second position positioned downstream in the sheet conveying direction. The surface of the paper can be printed by the image forming apparatus.

  In such an image forming system, an electrophotographic image forming apparatus is generally used. In an electrophotographic image forming apparatus, for example, yellow (Y), magenta (M), cyan (C), and black (K) toner images are developed on a plurality of photoconductors, and these toner images are intermediated. Images are formed by an intermediate transfer method in which toner images are sequentially transferred onto a transfer member and superimposed, and then the superimposed toner images are collectively transferred to a sheet. The image formed on the paper is heat-fixed in the fixing device, and the image formation is completed.

  By the way, if the total value of the density of each of the YMCK toners arranged to overlap each other exceeds a predetermined value, there is a possibility that toner peeling or the like due to insufficient toner fixing may occur. This is presumably because when a large amount of toner is stacked at the same location, all the toner cannot be heated sufficiently, and the toner image is easily peeled off from the paper due to insufficient fixing temperature.

  In order to cope with such a problem, conventionally, toner density adjustment is generally performed to limit the total amount of toner that can be printed in the same place (for example, Patent Document 2). For example, as shown in FIG. 7, when the maximum printable density (Dmax) at which toner peeling does not occur is set to 200%, when printing data having a total toner amount of 300% is input, the total toner amount is 200. Each channel is compressed at an equal ratio so that it becomes%.

  Note that, in an image forming system configured by connecting two image forming apparatuses in series as in Patent Document 1, different surfaces are printed by the first image forming apparatus and the second image forming apparatus. , Form different images. Therefore, a method has been used in which the toner density is adjusted so as not to exceed the maximum printable density for each image, and image data is transmitted to each image forming apparatus.

JP 2013-57748 A JP 2003-186277 A

  However, if printing is performed with the maximum printable density limited as described above, the gradation is limited as compared with the case where all YMCK are printed at a density of 100%. For this reason, it is difficult to express the gradation intended by the user.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming system and a program capable of expressing a gradation intended by a user without limiting the total amount of toner that can be printed. And

In order to solve the above problems, an image forming system according to claim 1 is provided.
In an image forming system in which a plurality of image forming apparatuses are arranged in series,
Determination means for determining whether the toner amount per pixel exceeds a predetermined threshold in at least some of the images when an image based on the acquired image data is formed on the acquired image data;
The image data determined by the determination means that the toner amount per pixel exceeds a predetermined threshold in at least some images is divided and divided so that the toner amount per pixel does not exceed the predetermined threshold. A dividing means for generating image data;
Control means for controlling the plurality of image forming apparatuses to share the image formation of the divided image data generated by the dividing means.

According to a second aspect of the present invention, in the image forming system according to the first aspect,
Having a plurality of transport routes, comprising transport means for transporting paper using the transport routes,
The control unit determines the transport route used for transporting a sheet based on a determination result by the determination unit.

According to a third aspect of the present invention, in the image forming system according to the first or second aspect,
The dividing unit generates divided image data including image data of only a specific color toner among the entire image data.

According to a fourth aspect of the present invention, in the image forming system according to the third aspect,
The plurality of image forming apparatuses perform image formation using yellow, magenta, cyan, and black toners,
The dividing means generates divided image data composed of image data of only yellow toner among the entire image data.

According to a fifth aspect of the present invention, in the image forming system according to any one of the first to fourth aspects,
The dividing unit selects one division pattern from the plurality of division patterns based on the remaining amount of toner of the plurality of image forming apparatuses, and generates divided image data by dividing the image data based on the selected division pattern. It is characterized by doing.

The program according to claim 6 is:
A computer in an image forming system in which a plurality of image forming apparatuses are arranged in series,
Determining means for determining whether the amount of toner per pixel exceeds a predetermined threshold in at least some of the images when an image based on the acquired image data is formed on the acquired image data;
A dividing unit that divides the image data for which the toner amount per pixel is determined to exceed a predetermined threshold in at least a part of the image so that the toner amount per pixel does not exceed the predetermined threshold. ,
Control means for controlling the plurality of image forming apparatuses to share image formation of the divided image data divided by the dividing means;
To function as.

  According to the present invention, it is possible to provide an image forming system and program capable of expressing gradations intended by a user without limiting the total amount of toner that can be printed.

1 is a diagram illustrating a schematic configuration of an image forming system. FIG. 2 is a block diagram illustrating functional configurations of a first image forming apparatus and a second image forming apparatus. It is a figure which shows an example of the paper conveyance method which concerns on this embodiment. It is a figure which shows an example of the division method of the image data which concerns on this embodiment. 4 is a flowchart illustrating an operation of the image forming system according to the present embodiment. 4 is a flowchart illustrating an operation of the image forming system according to the present embodiment. It is a figure explaining the conventional toner density adjustment method.

Embodiment
Hereinafter, an image forming system according to an embodiment of the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples. In addition, in the following description, what has the same function and structure attaches | subjects the same code | symbol, and abbreviate | omits the description.

(Configuration of image forming system)
FIG. 1 shows a schematic configuration diagram of an image forming system 1 in the present embodiment.
As shown in FIG. 1, the image forming system 1 includes a sheet feeding device 10, a first image forming device 20, a reversing device 30, a second image forming device 40, and a post-processing device from the upstream side of the sheet conveyance path. It has a series tandem configuration in which 50 etc. are connected in series.

  In the image forming system according to the present embodiment, when the total amount of toner per pixel of an image to be formed does not exceed the maximum printable density (Dmax), the first image forming apparatus 20 and the second image forming apparatus Each of 40 performs image formation on one side of the paper. Therefore, when a single-side mode job for forming an image on one side of a sheet is executed, an image is formed on the surface of the sheet by operating the first image forming apparatus 20 or the second image forming apparatus 40. The When a duplex mode job for forming an image on both sides of a sheet is executed, the first image forming apparatus 20 is operated to form an image on one side (for example, the back side) of the sheet, and the second When the image forming apparatus 40 is operated, an image is formed on the other surface (for example, the front surface) of the sheet. In the present embodiment, in the double-side mode, the first image forming apparatus 20 forms an image on the back side of the sheet and the second image forming apparatus 40 forms an image on the front side of the sheet. The image forming apparatus 20 may form an image on the front side of the sheet, and the second image forming apparatus 40 may form an image on the back side of the sheet.

  The paper feeding device 10 is called a PFU (Paper Feeder Unit), and includes a plurality of paper feeding trays, paper feeding means including a paper feeding roller, a separation roller, a paper feeding / separation rubber, a feeding roller, and the like. Prepare. Each paper feed tray stores papers identified in advance for each paper type (paper type, basis weight, paper size, etc.), and the first image is fed from the top of the paper one by one by the paper feeding means. The paper is conveyed to the paper conveyance unit of the forming apparatus 20.

  The first image forming apparatus 20 reads an image from a document, forms an image of the read image on a sheet, or print data in a page description language format such as a PDL (Page Description Language) format or a Tiff format from an external device or the like. Print setting data is received, and an image is formed on a sheet based on the received print data, print setting data, and the like. The first image forming apparatus 20 includes an image reading unit 21, an operation display unit 22, a print unit 23, and the like.

  The image reading unit 21 includes an automatic document feeding unit called ADF (Auto Document Feeder) and a reading unit, and reads images of a plurality of documents based on setting information received by the operation display unit 22. The document placed on the document tray of the automatic document feeder is conveyed to a contact glass that is a reading location, an image on one or both sides of the document is read by an optical system, and an image of the document is read by a CCD (Charge Coupled Device) 211. Is read. Here, the image means not only image data such as graphics and photographs but also text data such as characters and symbols.

  The operation display unit 22 includes an LCD (Liquid Crystal Display) 221, a touch panel provided to cover the LCD 221, various switches and buttons, a numeric keypad, an operation key group, and the like.

  The print unit 23 performs electrophotographic image forming processing, and includes various units related to print output, such as a paper feeding unit 231, a paper transport unit 232, an image forming unit 233 for each color, and a fixing unit 234. The

  The sheet feeding unit 231 includes a plurality of sheet feeding trays and sheet feeding means including a sheet feeding roller, a separation roller, a sheet feeding / separating rubber, a feeding roller, and the like provided for each sheet feeding tray. Each paper tray stores paper that has been identified in advance for each paper type (paper type, basis weight, paper size, etc.), and feeds the paper from the top of the paper one by one to the paper transport section. It is conveyed toward.

  The sheet conveying unit 232 conveys the sheet conveyed from the sheet feeding device 10 or the sheet feeding unit 231 onto a sheet conveying path to the image forming unit 233 that passes through a plurality of intermediate rollers, registration rollers, and the like, and forms an image. The sheet is conveyed to the secondary transfer position of the unit 233.

  The paper transport unit 232 includes a reverse transport unit 232a. The reverse conveyance unit 232 a switches back the paper discharged from the fixing unit 234 by using a reverse roller or the like, and conveys the paper to the printing unit 23.

  The image forming unit 233 includes a photosensitive drum, a charging device, an exposure device, a developing device, a primary transfer roller, a cleaning device, and the like, and generates an output product in which an image is formed on a sheet based on print image data. When the first image forming apparatus 20 forms a color image, an image forming unit 233 is provided for each color.

  In the image forming unit 233y that forms a yellow (Y) image, the surface of the photosensitive drum charged by the charging device is irradiated with light according to the yellow (Y) print image data from the exposure device, and the electrostatic latent image. Is written. Then, a charged yellow (Y) toner is attached to the surface of the photosensitive drum on which the electrostatic latent image is written by the developing device, and the electrostatic latent image is developed. The toner adhering to the photosensitive drum by the developing device is transferred to the intermediate transfer belt 233a at the primary transfer position where the primary transfer roller is arranged by rotating the photosensitive drum at a constant speed. After the toner is transferred to the intermediate transfer belt 233a, the cleaning device removes residual charges, residual toner, and the like on the surface of the photosensitive drum, and the removed toner is collected in a toner collection box.

  Similarly, the image forming units 233m, 233c, and 233k for each color include a charging device, an exposure device, a developing device, a primary transfer roller, a cleaning device, and the like disposed around the photosensitive drum, and are provided with magenta (M), cyan ( C) and black (K) toner images are formed.

  The toner images of the respective colors transferred to the intermediate transfer belt 233a are collectively transferred onto the sheet at the secondary transfer position where the secondary transfer roller is disposed.

  The fixing unit 234 includes a fixing heater, a fixing roller, a fixing external heating unit, and the like, and heat-fixes the toner image transferred onto the sheet.

  The paper fixed by the fixing unit 234 is conveyed to the reversing device 30 by a paper discharge roller or the like, or is conveyed to the reverse conveying unit 232a of the paper conveying unit 232.

The reversing device 30 includes a discharge tray T1, a stacker 31 having a reversing roller, and the like, and is installed between the first image forming apparatus 20 and the second image forming apparatus 40.
The reversing device 30 functions as a conveying unit, and in accordance with an instruction from the first image forming device 20, the sheet on which one image is formed by the first image forming device 20 is transferred to the second image forming device 40. It is conveyed or discharged to the paper discharge tray T1. When the sheet conveyed to the second image forming apparatus 40 needs to be reversed, the sheet is reversed by switching back the sheet with a reversing roller or the like included in the stacker 31, and the second image forming apparatus 40. Transport to.

The second image forming apparatus 40 includes a print unit 43 and the like, and forms an image on a sheet in accordance with an instruction from the first image forming apparatus 20.
Note that the print unit 43 included in the second image forming apparatus 40 has the same configuration as the print unit 23 included in the first image forming apparatus 20, and thus description thereof is omitted.

  The post-processing device 50 includes various post-processing units such as a reversing unit, a sorting unit, a stapling unit, a punch unit, and a folding unit, and a plurality of paper discharge trays T2 to T4, etc., and instructions from the first image forming apparatus 20 Accordingly, various types of post-processing are performed on the paper conveyed from the second image forming apparatus 40, and the post-processed paper is discharged to one of the paper discharge trays T2 to T4.

  In the image forming system 1 according to the present exemplary embodiment, when a job in the single-side mode is executed in the first image forming apparatus 20, the sheet is discharged to the paper discharge tray T <b> 1 and the second image forming apparatus 40. When the single-sided mode job is executed, the paper is discharged to the paper discharge tray T2. Further, when a job in the duplex mode is executed, the sheet is discharged to the discharge tray T3.

  Not limited to this, when a job in the single-side mode is executed in the first image forming apparatus 20, paper is temporarily stored in the stacker 31 of the reversing device 30, and the stacker 31 is used as a discharge tray. It may be used. In addition, a paper transport path is provided through the reversing device 30, the second image forming apparatus 40, and the post-processing device 50 from the carry-out port of the first image forming apparatus 20. The paper discharge tray T4 may be used as a paper discharge tray from which paper is discharged when a job in the single-side mode is executed in the first image forming apparatus 20.

  In the present embodiment, the first image forming apparatus 20 including the image reading unit 21, the operation display unit 22, and the controller 24 is located upstream of the second image forming apparatus 40 in the sheet conveyance path of the image forming system 1. However, the present invention is not limited to this, and the first image forming apparatus 20 and the second image forming apparatus 40 may be provided in an opposite positional relationship.

FIG. 2 shows a functional configuration of the first image forming apparatus 20 and the second image forming apparatus 40 in the present embodiment.
As shown in FIG. 2, the first image forming apparatus 20 includes an image reading unit 21, an operation display unit 22, a printing unit 23, a controller 24, an image control board 25, a communication unit 26, and the like. The first image forming apparatus 20 is connected to an external apparatus 2 on the network 3 via a LANIF (Local Area Network InterFace) 244 of the controller 24 so that data can be transmitted and received between them.

  The image reading unit 21 includes the automatic document feeding unit and reading unit described above, and the image reading control unit 210. The image reading control unit 210 controls the automatic document feeding unit, the reading unit, and the like based on an instruction from the control unit 250 to realize a scanner function for reading images of a plurality of documents. The analog image data read by the image reading unit 21 is output to the reading processing unit 253, where the reading processing unit 253 performs A / D conversion and various image processing.

  The operation display unit 22 includes the above-described LCD 221, touch panel, and the like, and an operation display control unit 220. The operation display control unit 220 displays various screens for inputting various setting conditions, various processing results, and the like on the LCD in accordance with a display signal input from the control unit 250. The operation display control unit 220 outputs operation signals input from various switches, buttons, numeric keys, operation key groups, a touch panel, and the like to the control unit 250.

  The print unit 23 as the first image forming unit includes the above-described units related to print output, such as the paper feeding unit 231, the paper transport unit 232, the image forming unit 233 of each color, the fixing unit 234, and the print control unit 230. Prepare. The print control unit 230 controls the operation of each unit of the print unit 23 such as the image forming unit 233 for each color in accordance with an instruction from the control unit 250, and forms an image based on the print image data input from the writing processing unit 258. To do.

The controller 24 manages and controls data input to the image forming system 1 from the external device 2 connected to the network 3, and prints target data (print data and print setting data) from the external device 2. The image data received and developed by developing the print data and the print setting data are transmitted to the image control board 25.
The controller 24 includes a controller control unit 241, a DRAM (Dynamic Random Access Memory) control IC 242, an image memory 243, a LANIF 244, and the like.

  The controller control unit 241 comprehensively controls the operation of each unit of the controller 24 and develops print data input from the external apparatus 2 via the LANIF 244 to generate bitmap format image data.

  The DRAM control IC 242 controls transfer of print data received by the LANIF 244 to the controller control unit 241 and writing / reading of image data and print setting data to / from the image memory 243. The DRAM control IC 242 is connected to the DRAM control IC 255 of the image control board 25 via a PCI (Peripheral Components Interconnect) bus. The image data and print setting data to be printed are displayed in accordance with instructions from the controller control unit 241. Read from the memory 243 and output to the DRAM control IC 255.

  The image memory 243 is composed of a volatile memory such as a DRAM, and temporarily stores image data and print setting data.

  The LANIF 244 is a communication interface for connecting to a network 3 such as a network interface card (NIC) or a modem such as a modem, and receives print data and print setting data from the external device 2. The received print data and print setting data are output to the DRAM control IC 242.

  The image control board 25 includes a control unit 250, a nonvolatile memory 251, a RAM (Random Access Memory) 252, a reading processing unit 253, a compression IC 254, a DRAM control IC 255, an image memory 256, a decompression IC 257, a writing processing unit 258, and the like.

  The control unit 250 is configured by a CPU (Central Processing Unit) or the like, reads a system program and various application programs stored in the nonvolatile memory 251, expands them in the RAM 252, and expands them in the RAM 252. Various processes are executed in cooperation with the program, each part of the first image forming apparatus 20 is centrally controlled, and the entire image forming system 1 is comprehensively managed.

  Further, the control unit 250 is based on image data and print setting data input from the external device 2 via the controller 24, or image data input from the image reading unit 21 and setting information set by the operation display unit 22. Job data and compressed image data are generated. Then, the control unit 250 transmits the generated job data and compressed image data to the second image forming apparatus 40 and executes the job in cooperation with the second image forming apparatus 40.

  A job is a series of operations related to image formation. For example, when a copy made of a document of a predetermined page is created, a series of operations related to image formation of a document of a predetermined page is one job. Data for executing this job operation is job data.

  The nonvolatile memory 251 stores the above-described system program, various application programs, various data, and the like. These programs are stored in the form of computer readable program codes, and the control unit 250 sequentially executes operations according to the program codes.

The RAM 252 is, for example, a “DDR3 SDRAM (Double-Data-Rate3 Synchronous Dynamic Random Access Memory)” semiconductor memory, and is configured to be capable of high-speed data transfer. Note that the memory standards applied to the RAM 252 are not limited to those described above, and those having an appropriate data transfer rate can be appropriately selected.
The RAM 252 forms a work area that temporarily stores various programs executed by the control unit 250 and various data related to these programs.
The RAM 252 also has image data and print setting data input from the controller 24, or image data input from the image reading unit 21 and settings set by the operation display unit 22 when the image data is acquired. The job data generated by the control unit 250 based on the information is temporarily stored. The RAM 252 temporarily stores data transmitted / received via the communication unit 26.

  The reading processing unit 253 generates digital image data after performing various processing such as analog processing, A / D conversion processing, and shading processing on the analog image data input from the image reading unit 21. The generated image data is output to the compression IC 254.

  The compression IC 254 performs a compression process on the input digital image data and outputs it to the DRAM control IC 255.

  The DRAM control IC 255 controls the image data compression processing by the compression IC 254 and the decompression processing of the compressed image data by the decompression IC 257 in accordance with an instruction from the control unit 250, and performs input / output control of image data to the image memory 256. .

  For example, when an instruction to save image data read by the image reading unit 21 is input from the control unit 250, the DRAM control IC 255 causes the compression IC 254 to perform compression processing of the image data input to the reading processing unit 253. The compressed image data is stored in the compression memory 256a of the image memory 256. In addition, when image data is input from the DRAM control IC 242 of the controller 24, the DRAM control IC 255 causes the compression IC 254 to execute compression processing of the image data, and stores the compressed image data in the compression memory 256a of the image memory 256.

  Further, when a print output instruction for compressed image data is input from the control unit 250, the DRAM control IC 255 once transfers the compressed image data transferred from the RAM 252 to the compression memory 256a. Thereafter, the DRAM control IC 255 reads the compressed image data stored in the compression memory 256a, performs decompression processing by the decompression IC 257, and stores it in the page memory 256b. Further, when a print output instruction for image data stored in the page memory 256 b is input, the image data is read from the page memory 256 b and output to the writing processing unit 258.

  The image memory 256 includes a compression memory 256a and a page memory 256b composed of DRAM (Dynamic RAM). The compression memory 256a is a memory for storing compressed image data, and the page memory 256b is a memory for temporarily storing image data for print output.

  The decompression IC 257 performs decompression processing on the compressed image data.

  The write processing unit 258 generates print image data for image formation based on the image data input from the DRAM control IC 255 and outputs the print image data to the print unit 23.

  The communication unit 26 is a communication interface for connecting to a network to which each device constituting the image forming system 1 is connected, and transmits / receives various data to / from each device. The communication unit 26 uses, for example, a “10G Ethernet (registered trademark)” communication standard having a transmission rate of 10 Gbps, and speeds up communication with each device. Note that the communication standards applied to the communication unit 26 are not limited to those described above, and those having an appropriate data transfer rate can be appropriately selected.

Next, a functional configuration of the second image forming apparatus 40 in the present embodiment will be described.
As shown in FIG. 3, the second image forming apparatus 40 includes a print unit 43, an image control board 45, a communication unit 46, and the like.

  Since the printing unit 43 as the second image forming unit is the same as the printing unit 23 of the first image forming apparatus 20, the same parts are denoted by the same reference numerals and description thereof is omitted.

  The image control board 45 includes a control unit 450, a nonvolatile memory 451, a RAM 452, a DRAM control IC 455, an image memory 456, a decompression IC 457, a writing processing unit 458, and the like.

The control unit 450 includes a CPU and the like, reads a specified program from among system programs and various application programs stored in the nonvolatile memory 451, expands the program in the RAM 452, and cooperates with the program expanded in the RAM 452. Thus, various processes are executed to centrally control each unit of the second image forming apparatus 40.
Further, the control unit 450 executes the job based on the job data and the compressed image data received from the first image forming apparatus 20.

  The nonvolatile memory 451 stores the above-described system program, various application programs, various data, and the like. These programs are stored in the form of computer readable program codes, and the control unit 450 sequentially executes operations according to the program codes.

The RAM 452 is, for example, a “DDR3 SDRAM” standard semiconductor memory, and is configured to be capable of high-speed data transfer. Note that the memory standards applied to the RAM 452 are not limited to those described above, and those having an appropriate data transfer rate can be selected as appropriate.
The RAM 452 forms a work area for temporarily storing various programs executed by the control unit 450 and various data related to these programs.
The RAM 452 temporarily stores job data and compressed image data input from the first image forming apparatus 20 via the communication unit 46.

  The DRAM control IC 455 controls decompression processing of the compressed image data by the decompression IC 457 according to an instruction from the control unit 450, and performs input / output control of image data to the image memory 456.

  For example, when the compressed image data is transferred from the RAM 452, the DRAM control IC 455 once transfers the compressed image data to the compressed memory 456 a of the image memory 456. Thereafter, the DRAM control IC 455 reads the compressed image data stored in the compression memory 456a, performs decompression processing by the decompression IC 457, and stores it in the page memory 456b. Further, when a print output instruction for image data stored in the page memory 456 b is input, the image data is read from the page memory 456 b and output to the write processing unit 458.

  The image memory 456 includes a compression memory 456a and a page memory 456b configured by DRAM. The compression memory 456a is a memory for storing compressed image data, and the page memory 456b is a memory for temporarily storing image data for print output.

  The decompression IC 457 performs decompression processing on the compressed image data.

  The write processing unit 458 generates print image data for image formation based on the image data input from the DRAM control IC 455 and outputs the print image data to the print unit 43.

  The communication unit 46 is a communication interface for connecting to a network to which each device constituting the image forming system 1 is connected, and transmits / receives various data to / from each device.

(Print operation in series tandem configuration)
Next, a printing operation of the image forming system 1 in the present embodiment will be described. In this embodiment, the maximum printable density (Dmax) per pixel is 200%. In the present embodiment, the toner amount D indicates the total amount of toner per pixel when an image based on image data is formed.

First, the sheet conveying method according to the present embodiment will be described with reference to FIG.
When the toner amount D in the image data is 0% <D <200%, during the single-sided printing, as shown in FIG. 3 (A), the first image forming apparatus 20 (main machine) does not perform printing and inversion It is conveyed to the device 30. In the reversing device 30, the paper is turned upside down by the stacker 31 and conveyed to the second image forming device 40. In the second image forming apparatus 40 (sub machine), based on the image data transmitted from the first image forming apparatus 20, an image is formed on the surface of the sheet by the printing unit 43 and conveyed to the post-processing apparatus 50. Is done.
At the time of duplex printing, as shown in FIG. 3B, in the first image forming apparatus 20, an image is formed on the back surface of the sheet by the printing unit 23 based on the image data, and is conveyed to the reversing device 30. In the reversing device 30, the paper is turned upside down by the stacker 31 and conveyed to the second image forming device 40. In the second image forming apparatus 40, an image is formed on the surface of the sheet by the printing unit 43 based on the image data transmitted from the first image forming apparatus 20 and conveyed to the post-processing apparatus 50.
That is, when the toner amount D in the image satisfies D <Dmax, the image data is not divided and an image is formed on the back surface by the first image forming device 20 and on the front surface by the second image forming device 40. The

When the toner amount D in the image is 200% <D <400%, the image data is divided, and the first image forming apparatus 20 and the second image forming apparatus 40 share and form one image.
At the time of single-sided printing, as shown in FIG. 3C, printing is performed on the front surface by the first image forming device 20, and the reversing device 30 does not reverse the paper, and the second image forming device 40 again performs the front surface. Print on.
At the time of double-sided printing, as shown in FIG. 3D, after printing on the front surface by the first image forming apparatus 20, the paper is reversed and printed on the back surface by the reverse conveying unit 232 a, and the paper is put on the reverse apparatus 30 Transport. The reversing device 30 prints both sides again by the second image forming device 40 without reversing the paper.
That is, when D> Dmax, the image data is divided so that the toner amount D of the divided image data does not exceed Dmax to generate two divided image data, and the first image formation Different divided image data is transmitted to each of the apparatus 20 and the second image forming apparatus 40. Therefore, by performing each of image formation and fixing processing based on the divided image data, it is possible to perform image formation for image data exceeding Dmax without causing poor fixing.

  Next, a method for dividing image data will be described. FIG. 4 shows the concept of the image data dividing method.

  As shown in FIG. 4, four divided patterns of pattern A to pattern D are assumed. Note that the division pattern is not limited to this as long as the toner amount D of the image formed by each image forming apparatus can be controlled so as not to exceed Dmax.

In the pattern A, Y / M / C / K data is summed up in a predetermined order, and the portion where the sum exceeds 200% is divided, and the job (sub-side) executed by the second image forming apparatus 40 Job). Thereby, the division process by the control unit 250 can be simplified.
In the pattern B, only Y is divided into sub jobs, and M / C / K is a job (master job) executed by the first image forming apparatus 20. That is, in the present embodiment, the first image forming apparatus 20 and the second image forming apparatus 40 print twice at the same position, but there is a possibility that color misregistration may occur due to follow-up printing. Therefore, such a problem can be reduced by dividing only Y, which is the least noticeable of color misregistration.
In the pattern C, a portion exceeding 200% is divided into the sub-side jobs while maintaining the ratio of each color of Y / M / C / K. Thereby, a hue can be averaged.
In pattern D, Y / M / C / K is divided into two colors, and each of them is defined as a sub-side job and a master-side job. For example, it is divided into two colors, C / K and Y / M, and C / K toner is set in the first image forming apparatus 20 and Y / M toner is set in the second image forming apparatus 40. Thereby, material management can be facilitated.

In addition to this, for the purpose of increasing only the density of a specific color, for example, by setting only C / M of Y / M / C / K to be divided, the density of the two colors is increased. be able to.
The toner to be divided may be designated by the user from the external device 2 via the controller 24 or may be set by the user via the operation display unit 22.

Further, the division may be performed in consideration of the residual toner amount of each image forming apparatus. In the pattern C described above, the portion where the toner density exceeds 200% is set as the sub-side job, but the remaining toner amount of the first image forming apparatus 20 is small and the remaining toner amount of the second image forming apparatus 40 is. When there is a large amount of toner, the divided job is set as a master-side job, so that a shortage of toner can be avoided and the balance of consumption can be adjusted. Alternatively, a color with a high toner consumption speed may be targeted for division, and the color may be printed by the image forming apparatus with the larger remaining amount of toner.
Note that it is possible to divide the image data equally or to divide it at other ratios according to the remaining amount of toner.

  Note that the remaining toner amount of the first image forming apparatus 20 is stored in the nonvolatile memory 251, and the remaining toner amount of the second image forming apparatus 40 is stored in the first image forming apparatus 20 via the communication unit 46. And stored in the nonvolatile memory 251. The control unit 250 makes the above determination with reference to the remaining toner amount stored in the nonvolatile memory 251.

Next, processing performed by the image forming system 1 according to the first embodiment will be described using the flowchart of FIG.
First, the first image forming apparatus 20 receives a job (step S501). Here, the acceptance of the job is that image data and print setting data are input from the external apparatus 2 or image data read by the image reading unit 21 and setting information set by the operation display unit 22 are input. Point to.

  Next, the control unit 250 determines whether the received job is single-sided printing (step S502). When the control unit 250 determines that single-sided printing is performed (step S502: Yes), the control unit 250 determines whether there is a region where the toner amount D exceeds Dmax in the image as a determination unit (step S503). .

  When the control unit 250 determines that there is an area where D> Dmax (step S503: Yes), the control unit 250 uses the job (master-side job) executed by the first image forming apparatus 20 as the dividing unit. ) And the second divided image data of the job (sub-side job) executed by the second image forming apparatus 40 (step S504). Here, the control unit 250 performs control so that the toner amount D of the image formed by each divided image data does not exceed Dmax as described above.

  Next, the control unit 250 transmits the second divided image data of the sub-side job to the second image forming apparatus 40 via the communication unit 26 (step S505).

Next, in step S506, the control unit 250 controls the reverse conveyance unit 232a to reverse the paper.
In step S507, the control unit 250 controls the printing unit 23 to execute the master side job on the surface of the sheet. In other words, in the present embodiment, the sheet conveyed to the first image forming apparatus 20 is conveyed so that the back side is the image forming surface. Therefore, by reversing the sheet in step S506, the sheet is conveyed in step S507. An image can be formed on the surface.
In step S508, the control unit 250 controls the paper transport unit 232 to transport the paper to the reversing device 30, and the process proceeds to step S512.

  In step S503, when the control unit 250 determines that there is no region where D> Dmax (step S503: No), the control unit 250 processes image data that has not been divided via the communication unit 26 as a sub-side job. The second divided image data is transmitted to the second image forming apparatus 40 (step S509). Subsequently, the control unit 250 controls the paper transport unit 232 to transport the paper to the reversing device 30 (step S510).

  When the sheet is conveyed to the reversing device 30, the control unit 250 controls the stacker 31 as a control unit to reverse the sheet (step S511). In step S <b> 512, the reversing device 30 conveys the sheet to the second image forming device 40.

  In the second image forming apparatus 40, when the control unit 450 receives the second divided image data of the sub-side job via the communication unit 46 and the sheet is conveyed to the second image forming apparatus 40, the control unit 450 450 controls the print unit 43 to execute the sub-side job on the front side of the sheet (step S513). Thus, single-sided printing is completed, and the control is finished.

In step S502, if the control unit 250 determines that it is not single-sided printing (step S502: No), that is, if it is determined that it is double-sided printing, the process proceeds to step S514.
In step S514, the control unit 250 determines whether there is a region in which the toner amount D exceeds Dmax in the image on the back surface, the front surface, or both as a determination unit.
When the controller 250 determines that there is no region where D> Dmax (step S514: No), the process proceeds to step S515.

  In step S515, the control unit 250 transmits the image data of the front surface that is not divided via the communication unit 26 to the second image forming apparatus 40 as the second divided image data of the sub-side job. Subsequently, the control unit 250 controls the printing unit 23 to execute the master side job (step S516), and forms an image on the back side of the sheet. Next, the control unit 250 controls the paper transport unit 232 to transport the paper to the reversing device 30 (step S517).

  When the sheet is conveyed to the reversing device 30, the control unit 250 controls the stacker 31 as a control unit to reverse the sheet (step S511). In step S <b> 512, the reversing device 30 conveys the sheet to the second image forming device 40.

  In the second image forming apparatus 40, when the control unit 450 receives the second divided image data of the sub-side job via the communication unit 46 and the sheet is conveyed to the second image forming apparatus 40, the control unit 450 450 controls the print unit 43 to execute the sub-side job (step S513). As described above, double-sided printing is completed when there is no region where D> Dmax, and the control ends.

  When the control unit 250 determines that there is an area where D> Dmax (step S514: Yes), the process proceeds to step S601 in FIG. In step S <b> 601, the control unit 250 serves as the first divided image data of the job (master side job) executed by the first image forming apparatus 20 on the surface where the region where D> Dmax exists as the dividing unit. Then, it is divided into second divided image data of a job (sub-side job) executed by the second image forming apparatus 40. For example, when there is an area where D> Dmax exists on the back surface and there is no area where D> Dmax exists on the front surface, the control unit 250 divides image data only on the back surface, and divides image data for the front surface. Not performed.

  Next, the control unit 250 transmits the second divided image data of the sub-side job to the second image forming apparatus 40 via the communication unit 26 (step S602).

Next, in step S603, the control unit 250 controls the printing unit 23 to execute a master-side job for the back side of the sheet. In step S604, the control unit 250 controls the reverse conveyance unit 232a to invert the sheet, and then executes the master side job on the surface of the sheet (step S605). That is, at the time of duplex printing, the first image forming apparatus 20 performs image formation on the front surface and the back surface as described above.
In step S <b> 606, the control unit 250 controls the paper transport unit 232 to transport the paper to the reversing device 30.

  When the sheet is conveyed to the reversing device 30, the reversing device 30 conveys the sheet to the second image forming apparatus 40 (step S607).

  In the second image forming apparatus 40, when the control unit 450 receives the second divided image data of the sub-side job via the communication unit 46 and the sheet is conveyed to the second image forming apparatus 40, the control unit 450 450 controls the print unit 43 to execute the sub-side job on the surface of the paper (step S608). In step S609, the control unit 250 controls the reverse conveyance unit 232a to reverse the paper, and then executes the master side job on the back surface of the paper (step S610). As described above, double-sided printing is completed when there is a region where D> Dmax, and the control ends.

  As described above, in the image forming system 1 according to the present embodiment, the first image forming apparatus 20 and the second image forming apparatus 40 are connected to each other so as to be able to transmit and receive data. When the toner amount D exceeds Dmax, the control unit 250 divides the image data into the first divided image data of the master side job and the second divided image data of the sub side job. That is, the image data is divided so as not to exceed Dmax, and the first image forming apparatus 20 and the second image forming apparatus 40 perform image formation / fixing processing twice. Therefore, even when the toner amount D exceeds Dmax, an image can be formed without causing a fixing failure or the like, so that it is possible to form a high density image or an image with high gradation.

  In the present embodiment, the paper transport path is changed according to the toner density. That is, when the toner amount D does not exceed Dmax, image formation is performed by only one image forming apparatus for one image as in normal image formation, so that there is no possibility of reducing work efficiency.

  Note that if there is an area where D> Dmax on only one side in double-sided printing, the divided image data is generated only on the one side, and the image data is not divided on the other side. Accordingly, in such a case, only the first image forming apparatus 20 inverts the paper in the image forming apparatus and forms an image on both sides, and the second image forming apparatus 40 does not invert the sheet and only the image on one side is formed. Form. Or the reverse may be sufficient. By doing so, the number of sheet reversals in the image forming apparatus can be reduced, and the printing time can be shortened.

[Other Embodiments]
As mentioned above, although concretely demonstrated based on embodiment based on this invention, said embodiment is a suitable example of this invention, and is not limited to this.

For example, in the above-described embodiment, the generation of the divided image data is automatically performed by the control unit 250. However, the present invention is not limited to this, and the division condition set by the user by the external device 2 is set via the controller 24. Alternatively, it may be transmitted to the image control board 25 via the operation display unit 22.
When the generation of the divided image data is automatically controlled by the control unit 250, the user's trouble can be saved. On the other hand, when the user sets the division method, the user can freely set the division method according to the user's preference. For example, adjustment such as increasing the density of a specific color is possible.

  In the above embodiment, the image forming system 1 using two image forming apparatuses has been described. However, the present invention is not limited to this. Since the effect of the present invention can be obtained if the divided image data can be transmitted to a plurality of units to form an image, a configuration using three or more image forming apparatuses may be employed.

  In the above embodiment, the divided image data is generated only for the surface where the region where D> Dmax exists during double-sided printing. However, the present invention is not limited to this, and there is a region where D> Dmax exists. The divided image data may always be generated for both sides.

In the above embodiment, the control unit 250 functions as a determination unit, a division unit, and a control unit. However, the present invention is not limited to this. For example, a control unit such as a personal computer as the external device 2 has the same function. It is also possible to perform control separately from the image forming apparatus.

  In addition, the detailed configuration of each apparatus constituting the image forming system 1 and the detailed operation of each apparatus can be changed as appropriate without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Image forming system 2 External apparatus 3 Network 10 Paper feeding apparatus 20 1st image forming apparatus 23 Print part 24 Controller 25 Image control board 250 Control part (a judgment means, a dividing means, a control means)
26 communication unit 30 reversing device (conveying means)
31 Stacker 40 Second image forming apparatus 43 Print unit 45 Image control board 450 Control unit 46 Communication unit 50 Post-processing device

Claims (6)

In an image forming system in which a plurality of image forming apparatuses are arranged in series,
Determination means for determining whether the toner amount per pixel exceeds a predetermined threshold in at least some of the images when an image based on the acquired image data is formed on the acquired image data;
The image data determined by the determination means that the toner amount per pixel exceeds a predetermined threshold in at least some images is divided and divided so that the toner amount per pixel does not exceed the predetermined threshold. A dividing means for generating image data;
An image forming system comprising: control means for controlling the plurality of image forming apparatuses to share image formation of the divided image data generated by the dividing means. Having a plurality of transport routes, comprising transport means for transporting paper using the transport routes,
The image forming system according to claim 1, wherein the control unit determines the transport route used for transporting a sheet based on a determination result by the determination unit.   3. The image forming system according to claim 1, wherein the dividing unit generates divided image data including image data of only a specific color toner in the entire image data. The plurality of image forming apparatuses perform image formation using yellow, magenta, cyan, and black toners,
The image forming system according to claim 3, wherein the dividing unit generates divided image data including image data of only yellow toner out of the entire image data.   The dividing unit selects one division pattern from the plurality of division patterns based on the remaining amount of toner of the plurality of image forming apparatuses, and generates divided image data by dividing the image data based on the selected division pattern. The image forming system according to claim 1, wherein the image forming system is an image forming system. A computer in an image forming system in which a plurality of image forming apparatuses are arranged in series,
Determining means for determining whether the amount of toner per pixel exceeds a predetermined threshold in at least some of the images when an image based on the acquired image data is formed on the acquired image data;
A dividing unit that divides the image data for which the toner amount per pixel is determined to exceed a predetermined threshold in at least a part of the image so that the toner amount per pixel does not exceed the predetermined threshold. ,
Control means for controlling the plurality of image forming apparatuses to share image formation of the divided image data divided by the dividing means;
Program to function as.

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