JP6787050B2 - Image formation system and control program of image formation system - Google Patents

Description

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

In recent years, in the color printing industry, an image forming apparatus such as an electrophotographic printer has been widely used in place of the conventional offset printing apparatus.

In such a printer, in order to stabilize the color of the image and the formation position of the line with high accuracy, a test chart formed on the paper by a reading unit arranged on the downstream side in the transport direction of the image forming unit, or Optically read the color of the actual output image. Then, there is an image forming apparatus for stabilizing the image quality by changing the image forming conditions and the like according to the result (for example, Patent Document 1).

In this reading unit, a light source and a sensor array in which a plurality of optical elements are arranged in a line in the main scanning direction are used to irradiate the image-formed paper with light, and the reflected light is used as an optical system such as an optical lens. Reading is performed by forming an image on the optical element through the image.

Since the reading signal of the optical element of the reading unit varies from optical element to optical element, shading correction is generally performed based on the reading signal obtained by reading the white reference plate to correct the variation among the optical elements.

However, the temperature of the optical element, optical system, etc. of the reading unit rises due to heat generated from the light source and radiant heat from the paper to be read, and this temperature rise increases the sensitivity of the optical element and the optical system due to thermal deformation. Due to the distortion of the reading signal, the read signal fluctuates.

In response to such a problem, in the image reading device disclosed in Patent Document 2, a first generation unit that generates reference shading data indicating a reference reading level for each pixel from the reading data of the white reference plate, a pixel of interest, and a pixel of interest Corrected shading data is generated by correcting the reference reading level of the reference shading data for each pixel of interest to the reading level at the position shifted in the pixel arrangement direction, based on the reference reading level of the peripheral pixels of the pixel of interest. When each of the plurality of lenses forms an image of the reflected light or transmitted light of the light emitted by the second generation unit and the irradiation unit on the reading target, the photoelectric conversion element performs photoelectric conversion of the plurality of pixel data. By having a calculation unit that performs a correction calculation based on the correction shading data, fluctuations in the read signal due to temperature changes are prevented.

JP-A-2015-230352 JP-A-2015-39146

However, the technique disclosed in Patent Document 2 aims to solve the problem of preventing fluctuations in the read signal due to temperature changes, and Patent Document 2 considers the timing of generating reference shading data and the like. Absent.

In particular, in a reading device that reads an image on an image-formed paper as in Patent Document 1, there is a case where the image is continuously formed on a plurality of sheets while reading and feeding back to the image forming conditions. .. In such a case, if the reference shader data generated before the temperature rise is applied even though the temperature has risen, there is a possibility that the color and density cannot be read accurately.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an image forming system capable of estimating the influence of a temperature change of a reading unit and performing calibration at an appropriate timing.

The above object of the present invention is achieved by the following means.

(1) A transport unit that transports paper and
An image forming unit that forms an image on the paper conveyed by the conveying unit,
A reading unit provided on the downstream side in the transport direction from the image forming unit and reading an image on paper formed by the image forming unit.
A temperature sensor that detects the temperature of the CCD substrate of the reading unit, and
A proofreading unit that calibrates the reading unit and
A storage unit that stores temperature characteristics indicating the amount of change in the color difference of the reading unit with respect to the temperature change amount of the reading unit.
During execution of a continuous printing job for forming an image on a plurality of sheets of continuously conveyed sheets, the proofreading unit calibrates the reading unit based on the temperature characteristics and the amount of temperature change of the reading unit. The control unit that determines the timing and
An image forming system comprising.

(2) The control unit changes the color difference from the previous calibration based on the temperature change amount calculated from the temperature of the reading unit and the current temperature when the calibration was executed immediately before, and the temperature characteristics. The image forming system according to (1) above, wherein the timing at which the amount reaches a predetermined allowable threshold value is calculated, and the calculated timing is determined as the timing at which the calibration is next executed.

(3) The image forming system according to (2) above, comprising a setting reception unit that accepts the setting of the allowable threshold value by the user.

(4) The setting receiving unit can accept a hold setting for suspending execution of a continuous print job using the reading unit.
The continuous printing job is suspended until the temperature change amount per unit time of the reading unit becomes equal to or less than a predetermined value when the hold setting is accepted, according to the above (3). Image formation system.

(5) The control unit determines, based on the setting of the continuous printing job, whether or not the determined execution timing of the proofing is in the process of transporting any of a plurality of sheets. When it is determined that the paper is being conveyed, the execution timing is changed between the sheets immediately before the paper, and / or the transfer timing of the paper is delayed, from the above (1) to (4). The image forming system according to any one.

(6) The calibration unit is provided with a reference plate for calibration.
The image forming system according to any one of (1) to (5) above, wherein the calibration is a shading correction using the reference plate, and the shading correction includes different types of shading correction.

(7) When the control unit is set to read the reading unit in the printing setting of the continuous printing job, and the temperature change amount per unit time of the reading unit exceeds a predetermined value. Suspends the execution of the continuous print job and starts the execution of the suspended continuous print job when the value falls below the predetermined value, from the above (1) to the above (3), the above (5), and The image forming system according to any one of (6) above.

(8) An image forming system provided on the downstream side in the transport direction with respect to the image forming section and including a reading section for reading an image on paper formed by the image forming section and a calibration section for calibrating the reading section. It is a control program of
A step to start execution of a continuous printing job that forms an image on multiple sheets of continuously conveyed paper, and
A step of reading from the storage unit a temperature characteristic indicating the amount of change in the color difference of the reading unit with respect to the amount of temperature change of the reading unit.
The timing for calibrating the reading unit by the calibration unit is determined from the read temperature characteristics and the amount of temperature change of the reading unit calculated from the detection temperature of the temperature sensor that measures the temperature of the CCD substrate of the reading unit. Steps to do and
A control program for causing the image forming system to execute the step of executing the proof during the execution of the continuous printing job according to the determined timing.

(9) In the step of determining,
Based on the temperature change amount calculated from the temperature of the reading unit and the current temperature when the calibration was executed immediately before, and the temperature characteristics, the variation amount of the color difference from the immediately preceding calibration becomes a predetermined allowable threshold value. The control program according to (8) above, which calculates the arrival timing and determines the calculated timing as the timing for executing the calibration next.

According to the present invention, during execution of a continuous printing job for forming an image on a plurality of sheets of continuously conveyed sheets, the proofreading unit calibrates the reading unit based on the temperature characteristics of the reading unit and the amount of temperature change. Decide when to execute. As a result, color monitoring by the reading unit can be appropriately executed without unnecessarily reducing the productivity.

It is a figure which shows the schematic structure of the image formation system. It is a block diagram which shows the hardware structure of an image formation system. It is a figure which shows the structure of the reading part and the reading calibration part. It is a graph which shows the relationship between the temperature of a reading part and a color difference ΔE00. It is a graph which shows the temperature transition of a reading part. It is a schematic diagram which shows the transition of ΔE00 when the print job which performs the color audit in the conventional example is executed. It is a schematic diagram which shows the transition of ΔE00 when the print job which performs the color audit in the comparative example is executed. It is a schematic diagram which shows the transition of ΔE00 when the print job which performs the color audit in an Example is performed. It is a flowchart which shows the print control which concerns on 1st Embodiment. It is a figure which shows the subroutine of the process of FIG. It is a schematic diagram for demonstrating the calculation procedure of time Ta. It is a figure which shows typically the process of step S314. It is a figure which shows typically the process of step S322. It is a figure which shows typically the process of step S324. It is a figure which shows the setting screen of the operation panel in the modification 1. FIG. It is a flowchart which shows the print control which concerns on the modification 1. It is a schematic diagram which shows the transition of ΔE00 when the print job which performs the color audit in the modification 4 is performed.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same elements are designated by the same reference numerals, and duplicate description will be omitted. In addition, the dimensional ratios in the drawings are exaggerated for convenience of explanation and may differ from the actual ratios.

FIG. 1 is a diagram showing a schematic configuration of an image forming system according to an embodiment of the present invention. FIG. 2 is a block diagram showing a hardware configuration of an image forming system. FIG. 3 is a diagram showing a configuration of a reading unit and a reading proofreading unit.

As shown in FIGS. 1 to 3, the image forming system 100 includes an image forming device A1, a first post-processing device A2 including a reading unit 60, and a second post-processing device including a post-processing unit 80 that performs staple processing. It is composed of A3.

As shown in FIG. 2, the image forming system 100 includes a control unit 10, a storage unit 20, an image forming unit 30, a paper feed transport unit 40, an operation panel 50, a reading unit 60, a colorimeter 70, and a post-processing unit 80. And a communication interface (I / F) 90, which are interconnected via a bus for exchanging signals.

The control unit 10 is a CPU, and controls each unit of the device and performs various arithmetic processes according to a program. Further, the control unit 10 functions as an adjustment unit that adjusts the color of the image and the image formation position based on the image data obtained by reading the reading unit 60. As the color adjustment of the image, for example, the LUT for color conversion is adjusted from the image data (image signal) obtained by reading the image of the color chart, or the image formation condition of the image forming unit 30 is adjusted. As the image position adjustment, for example, the image formation position is adjusted from the detected edge of the paper or the position of the register mark image (mark image).

The storage unit 20 includes a ROM for storing various programs and various data in advance, a RAM for temporarily storing programs and data as a work area, a hard disk for storing various programs and various data, and the like. Image data for a color chart for color adjustment, temperature characteristic data of the reading unit 60, and the like are stored in the storage unit 20.

The image forming unit 30 includes an intermediate transfer belt 31, a photoconductor drum 32, a developing unit 33, a writing unit 34, a secondary transfer unit 35, and a fixing unit 36. The photoconductor drum 32, the developing unit 33, and the writing unit 34 each have a configuration corresponding to each color of yellow (Y), magenta (M), cyan (C), and black (K). For these, the notation of symbols other than Y is omitted.

The writing unit 34 of the image forming unit 30 exposes the surface of the charged photoconductor drum 32 based on the image data to form an electrostatic latent image. The developing unit 33 develops the formed electrostatic latent image with the toner of the developing unit 33 to form a toner image of each color on the surface of each photoconductor drum 32. This is sequentially superimposed on the intermediate transfer belt 31 by the primary transfer unit (not shown) of each color to form a full-color toner image. This toner image is transferred onto the paper S by the secondary transfer unit 35, and then heated and pressed by the fixing unit 36 to form a full-color image on the paper S.

(Paper feed transport unit 40)
The paper feed transport unit 40 includes a paper feed tray 41, a transport path 42 (42a to 42d), a plurality of transport rollers 43 (43a to 43c), a drive motor (not shown) for driving the paper feed tray 41, and a paper output tray 46. Be prepared.

The paper feed transport unit 40 rotates each transport roller 43 by driving a drive motor, feeds the paper S from the paper feed tray 41, and transports the paper S in the transport path 42.

The transport path 42 is composed of transport paths 42a and 42b in the image forming apparatus A1, a transport path 42c in the first post-processing device A2, and a transport path 42d in the second post-processing device A3.

The paper S fed from the paper feed tray 41 is conveyed in the transport path 42a. A resist roller 43a that adjusts the paper transfer timing by rotating and stopping by a clutch is arranged in the transfer path 42a.

The paper S transported through the transport path 42a and formed into an image by the image forming unit 30 is subjected to various processes according to the print settings of the print job via the transport paths 42c and 42d on the downstream side, and then outside the machine. It is ejected and placed on the output tray 46.

If the print setting of the print job is double-sided printing, the paper S on which an image is formed on one side is conveyed to the ADU transfer path 42b below the image forming apparatus A1. The paper S transported to the ADU transport path 42b is turned upside down in the switchback path, merges with the transport path 42a, and is image-formed again by the image forming unit 30.

(Operation panel 50)
The operation panel 50 is provided with a touch panel, a numeric keypad, a start button, a stop button, etc., and inputs various settings such as printing conditions and allowable thresholds for color difference fluctuation (described later), displays the state of the device, and inputs various instructions. Used for. The operation panel 50 functions as a "setting reception unit" that receives various settings in cooperation with the control unit 10.

(Colorimeter 70)
Before explaining the reading unit 60, the colorimeter 70 will be described. The reading unit 60 will be described later. The colorimeter 70 is provided on the downstream side in the transport direction with respect to the reading unit 60 in the transport path 42b. The colorimeter 70 spectrally measures the color of each color patch of the evaluation image formed on the paper S by the image forming unit 30, and acquires the color measurement data. The color measurement data is output in a color system such as XYZ. Each color patch of this evaluation image is similarly read by the reading unit 60 and converted into the same color system data such as XYZ. Then, the reading unit 60 is calibrated by comparing both data.

(Post-processing unit 80)
The post-processing unit 80 is provided in the transport path 42c. The post-processing unit 80 has a stacking unit and a staple unit for stacking papers, and after stacking a plurality of sheets of paper S at the stacking unit, the staple unit performs a flat binding process using staples. The bundle of flat-bound paper S is ejected onto the output tray 46. Further, the non-flat bound paper S is discharged as it is via the transport path 42c.

(Communication interface 90)
The communication interface 90 uses various local connection interfaces such as a network interface based on standards such as SATA, PCI ExpressS, USB, Ethernet (registered trademark), and IEEE 1394, and a wireless communication interface such as Bluetooth (registered trademark) and IEEE 802.11. Be done. A print job composed of print data and print settings from an external terminal such as a PC is received through the communication interface 90.

(Structure of reading unit 60)
Next, the reading unit 60 will be described. First, the configuration of the reading unit 60 will be described, and then the temperature characteristics of the reading unit 60 will be described.

As shown in FIGS. 1 and 3, the reading unit 60 is arranged in the transport path 42b and reads an image formed on the surface of the paper S transported from the transport path 42a on the upstream side. The control unit 10 adjusts the color and the image position from the image data obtained by the reading unit 60. The reading unit 60 includes a sensor array 61, an optical system 62, an LED (Light Emitting Diode) light source 63, a document glass 64, a temperature sensor 65, and a housing 66 for accommodating these.

The sensor array 61 is a color line sensor in which a plurality of optical elements (for example, CCD (Charge Coupled Device)) are arranged in a line along the main scanning direction, and the entire width range in the width direction of the paper S can be read. Is. The optical system 62 is composed of a plurality of mirrors and lenses. The light from the LED light source 63 passes through the original glass and illuminates the surface of the paper S passing through the reading position P1. The image at the reading position P1 is guided by the optical system 62 and is imaged on the sensor array 61. The document glass 64 faces the transport path 42b and prevents the inside of the housing 66 from becoming dirty. The temperature sensor 65 is arranged inside the housing 66 and detects the temperature in the vicinity of the CCD substrate on which the sensor array 61 is arranged.

The reading unit 60 reads an image from an optical element obtained by reading a pure white reference plate in order to compensate for density unevenness between optical elements caused by non-uniformity of the light source 63, variation in sensitivity of the optical element, and the like. Shading correction is performed from the signal to generate a correction value that compensates for sensitivity unevenness between pixels.

(Reading and proofreading unit 69)
Further, below the transport path 42b, a reading proofreading unit 69 provided with a proofreading plate is provided so as to face the original glass 64 of the reading unit 60. The reading and proofreading unit 69 functions as a "calibrating unit" in cooperation with the control unit 10.

The reading calibration unit 69 includes a rotating body 691, a rotating shaft 692, and a cleaning brush 693. A reading surface c1, a white surface c2, a black surface c3, and a cleaning brush 693 are formed on the outer peripheral surface of the rotating body 691. The rotating body 691 can be rotated by a drive motor (not shown) with the rotating shaft 692 as the center of rotation, and by rotating at a predetermined angle, each surface is moved to the reading position P1.

Normally, when the paper S is conveyed and the image of the surface of the paper S is read, the position is as shown in FIG. 3, and the white reading surface c1 is at the reading position P1 of the transfer path 42b.

The white surface c2 functions as a white reference plate (calibration plate) for determining a correction value of shading correction used when reading an image. The black surface c3 is used when detecting the edge of the conveyed paper S, and is colored black so as to be easily distinguishable from the color of the paper (usually white).

The cleaning brush 693 comes into contact with the original glass 64 and cleans the dirt adhering to the surface thereof. When cleaning the original glass 64, the rotating body 691 is rotated, for example, 5 to 10 times.

(Temperature characteristics of reader 60)
Next, the temperature characteristics of the reading unit 60 will be described with reference to FIGS. 4 and 5. FIG. 4 is a graph showing the relationship between the detected temperature of the temperature sensor 65 and the color difference ΔE00, and FIG. 5 is a graph showing the temperature transition of the reading unit 60. In the following, the evaluation and determination of the color difference will be described using ΔE00 of the CIE2000 color difference equation, but the present invention is not limited to this, and the evaluation and determination of the color difference may be performed using general ΔE. Here, the CIE2000 color difference formula is a color difference formula that corrects the difference between the measurement result and the visual evaluation. The color difference ΔE00 in FIG. 4 is based on the temperature when the white reference plate is read and shading correction is performed, and the temperature difference from the reference temperature (ΔT (° C.)) and the reading data (read signal) of the same white reference plate are used. ) Is converted to ΔE00.

As shown in FIG. 4, the color difference also increases as the amount of temperature change of the reading unit 60 increases. Further, as shown in FIG. 5, it can be seen that after the power of the image forming system 100 is turned on, the temperature change continues for a while, and it takes 10 minutes or more from the power on to the stabilization.

The temperature characteristic data is stored in the storage unit 20 in advance. The temperature characteristic data is a table that associates the relationship between the amount of temperature change and the color difference (ΔE00) (see FIG. 4), but is not limited to this, and is a linear function or 2 showing the relationship between the amount of temperature change and the color difference (ΔE00). It may be expressed by an nth-order function of the following or higher.

(Color audit)
Here, the color audit will be described. In commercial printing, there are colors that require accurate color reproducibility (hereinafter referred to as spot colors), such as corporate colors used in company logos and the like. Information (tag) indicating that the spot color is a spot color is attached to the print data of the print job for such a spot color. When image formation of print data including spot colors is performed, the output is subject to "color audit", and the tint is strictly controlled as compared with ordinary colors other than spot colors. When it is subject to color auditing, the reading unit 60 reads an image area on the paper in which an image is formed by the color signal of the special color. Then, the color data (L ^* a ^* b ^* ) calculated and converted from the read data is compared with the original color information (L ^* a ^* b ^* ) of the spot color to calculate ΔE00, which is within the permissible range. Judge whether or not.

FIG. 6 is a schematic diagram showing the transition of ΔE00 calculated from the reading data of the reading unit 60 when the print job for performing the color audit in the conventional example is executed. In the figure, shading correction is performed using the white reference plate (white surface c2) during the time 0 to 5 (sec). After that, two sheets of paper S on which a spot color (here, "RED") image is formed on the entire surface are continuously conveyed between 15 to 20 (sec) and 25 to 30 (sec), and at the reading position P1. It is read by the reading unit 60. The vertical length of the rectangular frame in FIG. 6 indicates the permissible range of the spot color audit, and the horizontal length indicates the audit timing (position of the spot color image) (the same applies to the following figures). In the example shown in the figure, it is shown that the allowable range is out of the range in a part of the second sheet. Color monitoring is performed in this way.

7 and 8 are schematic views showing the transition of ΔE00 calculated from the reading data of the reading unit 60 when the printing job for performing the same color audit as in FIG. 6 is executed. FIG. 7 is a comparative example, and FIG. 8 is an embodiment of the present embodiment. In FIG. 7, unlike FIG. 6, the print job is executed during a period in which the temperature change of the reading unit 60 is large, such as immediately after the power is turned on. Therefore, although the shading correction is performed in 0 to 5 sec, the color difference of the read data fluctuates due to the influence of the subsequent temperature change. Therefore, at the time of reading the first and second sheets of paper S for color monitoring, even if the image of the spot color formed in the image itself is normal, it is determined to be abnormal from the read data of the reading unit 60. ..

On the other hand, in the embodiment shown in FIG. 8, the timing is delayed as much as possible, the first shading correction is executed immediately before the scanning is executed, and then the shading correction is additionally executed between the papers. By doing so, even if a temperature change occurs, the reading data can be appropriately read at the time of reading the first and second sheets S for color audit by each shading correction executed immediately before. Can be obtained.

However, although high-precision reading can be performed by performing shading correction immediately before each paper transfer, shading correction cannot be performed between the sheets depending on the length (time) between the sheets to be conveyed. In some cases, it is necessary to widen the space between the sheets or interrupt the transportation, which deteriorates the productivity. Therefore, in the control of the present embodiment described below, by appropriately determining the execution timing, the color monitoring by the reading unit can be appropriately performed without unnecessarily reducing the productivity.

(Control to determine execution timing)
FIG. 9 is a flowchart showing a print control executed by the control unit 10 of the image forming system 100 according to the first embodiment, particularly a print control for executing shading correction during execution of a continuous print job. FIG. 10 is a diagram showing a subroutine of the processing of FIG.

(S101)
First, the control unit 10 is a print job in which the print job received via the communication interface 90 or the like executes reading by the reading unit 60, that is, a printing job including information on spot colors to be subject to color audit. Judge whether or not. If it is a print job for executing image reading (S101: YES), the process proceeds to step S102. On the other hand, if it is not a print job for executing image reading (S101: NO), the process proceeds to step S110.

(S110)
All image formation is executed on the paper to be sequentially conveyed based on the print job, and the print control is terminated (end).

(S102)
In this process, the control unit 10 executes shading correction. Specifically, the rotating body 691 of the reading calibration unit 69 is rotated by a predetermined amount, the white surface c2 is moved to the reading position P1, the reading by the reading unit 60 is executed, and the correction value of the shading correction is determined from the reading data. To do. After the shading correction is completed, the rotating body 691 is rotated again to move the reading surface c1 to the reading position P1.

It should be noted that this shading correction is executed at a preset timing (first time) or at a timing determined in step S103 described later (second and subsequent times). The shading correction performed first (first time) after receiving the print job may be executed when the print job is received, but it is better to execute it at the latest possible timing. Preferably, it is the timing immediately before the paper S to be read is conveyed to the reading unit 60 (see FIG. 8). Then, the time when this shading correction is executed and the detected temperature of the temperature sensor 65 are stored in the storage unit 20.

(S103)
In the next process, the execution timing of the shading correction to be executed next is calculated based on the shading correction performed immediately before.

(Subroutine of calculation of shading correction execution timing (S103))
FIG. 10 is a diagram showing a subroutine in step S103. In the subroutine shown in FIG. 10, the execution timing (time Ta) of the shading correction is tentatively determined in the previous processing (S301 to S305). Then, in the subsequent processing (S311 to S325), the execution timing (time Ta) tentatively determined in the previous stage is assigned. That is, whether or not the execution is actually possible at the time Ta is determined in consideration of the paper transport timing, and the provisionally determined execution timing is changed or the paper transport timing is changed as necessary.

Here, the time of the execution timing may be a relative time based on the time of the shading correction immediately before (the time when the correction is completed, the same shall apply hereinafter), or an absolute time may be adopted. Good. In the following description, it is assumed that the former relative time is adopted.

(Previous process)
FIG. 11 is a schematic diagram for explaining a procedure for calculating the time Ta. Hereinafter, the processing in the first stage of steps S301 to S305 will be described with reference to FIG.

(S301)
First, the control unit 10 acquires the current temperature from the detected temperature of the temperature sensor 65. The storage unit 20 stores the detection temperature of the temperature sensor 65 and the time in association with each other. This process is continuously executed after the power of the apparatus main body is turned on, for example, in a predetermined cycle (for example, 10 sec).

(S302)
In the next process, the temperature before a predetermined time is acquired from the storage unit 20. This predetermined time is, for example, 1 minute.

(S303)
Next, the reading unit 60 temperature characteristic data stored in the storage unit 20 is read out. Then, the color difference variation amount is calculated from the temperature difference (temperature change amount) between the detected temperature before the predetermined time acquired in step S302 and the current temperature and the temperature characteristic data read out in this step S303.

For example, when the temperature characteristic data as shown by the shading in FIG. 4 is used, if the amount of temperature change from 1 minute before is 1.2 ° C., the amount of color difference change is 0.18.

(S304)
Then, the color difference fluctuation amount (ΔE00 / sec) per unit time (hereinafter, simply referred to as “tilt amount”) is calculated from this color difference fluctuation amount. In the above example, the amount of inclination (ΔE00 / sec) = 0.003 (= 0.18 / 60).

(Color difference fluctuation allowance)
Here, the allowable amount of color difference fluctuation (hereinafter, also simply referred to as “allowable threshold value”) will be described. This permissible threshold value is a predetermined threshold value and is stored in the storage unit 20. This permissible threshold value may be set for each spot color, or the same permissible amount may be set for all the spot colors. In addition, the user may be able to change this allowance through the setting screen. An example of this setting screen will be described later.

(S305)
In the next process, the control unit 10 calculates the time Ta exceeding the permissible threshold value from the calculated color difference fluctuation amount per unit time. Here, it is estimated that the subsequent time will also change with the same amount of inclination (color difference fluctuation amount per unit time).

Here, it will be described with reference to FIG. The horizontal axis of FIG. 11 shows the time of shading correction immediately before as the reference time (time 0). The vertical axis shows the value when the power of the apparatus main body is turned on (cold start) and the shading correction is first performed as a reference (ΔE00 = 0).

For example, if the permissible threshold value is "0.2", the temperature difference calculated in step S304 from the temperature obtained by shading correction in the past (1 minute ago) and immediately before, and the inclination amount obtained from the temperature characteristic data. From (0.003), the time Ta is 67 sec (= 0.2 / 0.003).

The above is the process related to the provisional determination of the execution timing of the shading correction in the previous stage. Next, the subsequent processing for assigning the shading correction to the actually determined execution timing will be described.

(Second stage processing)
(S311)
First, the control unit 10 determines the position of the paper at each time from the print settings such as the paper type of the print job and the post-processing mode, and more specifically, the transfer timing of each paper passing through the reading position P1 of the reading unit 60. Plan) is calculated.

(S312)
Then, from the calculated paper transport timing, it is determined whether or not any of the papers is scheduled to be transported at the time Ta. If the paper is not conveyed at time Ta (S312: NO), the process proceeds to step S313, and if it is conveyed (S312: YES), the process proceeds to step S321.

(S313)
Here, it is determined whether or not the shading correction can be executed between the sheets (time). If it is feasible (S313: YES), the process proceeds to step S315, and if not possible (S313: NO), the process proceeds to step S314.

(S314)
In this case, since the shading correction cannot be executed between the papers set based on the print settings, the image formation timing (paper feeding, conveying timing) of the paper immediately after the time Ta is delayed.

Specifically, the shading correction execution time t1 (hereinafter, simply referred to as “execution time t1”) is secured. Here, the execution time t1 is a time from the start to the completion of the shading correction, and then the reading surface c1 is moved to the reading position P1 until the paper S can be read. FIG. 12 is a diagram schematically showing the process of step S314. The figure shows a state when a plurality of sheets (S1 to Sn) are continuously conveyed.

As shown in FIG. 12A, the time Ta is between the n-1th sheet Sn-1 and the nth sheet Sn, and the sheets are not conveyed. However, since the execution time t1 cannot be secured between the papers, the image formation timing of the nth sheet Sn is delayed and secured as shown in FIG. 12B.

(S315)
In this process, the execution timing of the shading correction is fixed at the time Ta calculated in step S305, and the process returns to the flow of FIG.

(S321)
Here, it is determined whether or not shading correction can be performed between the sheets. That is, it is determined whether or not the paper S is conveyed between the time Ta and the time Ta + t1. If it is feasible, the process proceeds to step S322 (S321: YES), and if not, the process proceeds to step S324 (S321: NO).

(S322)
FIG. 13 is a diagram schematically showing the process of step S322. In this process, since the nth sheet Sn is conveyed at the time Ta, the transfer end time of the sheet Sn-1 immediately before the time Ta, that is, the time Tb at which the rear end of the sheet Sn-1 passes through the reading position P1. Is calculated.

(S323)
In this process, the execution timing of the shading correction is fixed at the time Tb calculated in step S322, and the process returns to the flow of FIG.

(S324)
FIG. 14 is a diagram schematically showing the process of step S324. In this process, the image formation timing of the paper Sn at time Ta is delayed, and the shading correction execution time t1 is secured.

(S325)
In this process, the execution timing of the shading correction is fixed at the time Ta calculated in step S305, and the process returns to the flow of FIG.

(S104)
In this process, the control unit 10 controls the image forming unit 30 to form an image on the conveyed paper S according to the print setting of the print job. The paper S at this time is conveyed at the transfer timing based on the print settings of the print job, or at the transfer timing after the delay if the delay process is determined in step S103.

(S105)
The reading unit 60 reads the paper S on which the image is formed and conveyed.

(S106)
If the print job is not completed (S106: NO), the process proceeds to step S107. On the other hand, when the print job is completed, that is, when all the image formation is completed (S106: YES), the print control is terminated (end).

(S107)
It is determined whether or not it is the timing to execute the shading correction determined in step S103, and if it is the execution timing (S107: YES), the process proceeds to step S102 and the shading correction is executed. On the other hand, if it is not the execution timing (S107: NO), the process proceeds to step S104, and the subsequent processes are performed.

As described above, in the present embodiment, during the execution of the continuous printing job, the timing for executing the shading correction of the reading unit is determined from the temperature characteristics of the reading unit and the amount of temperature change, and the continuous printing job is determined according to the determined timing. Perform shading correction during execution of. By doing so, the implementation of unnecessary shading correction is suppressed, and the productivity is not unnecessarily reduced. In addition, it is possible to prevent the fluctuation of the color difference from exceeding a predetermined allowable amount, and the color audit can be appropriately executed.

(Modification example 1)
In the first embodiment described with reference to FIGS. 9 and 10, shading correction is executed when the print job setting performs reading by the reading unit 60, that is, when information on spot colors for color monitoring is included. The process of determining the timing was being performed. In the first modification described below, when it is estimated that the color difference fluctuates greatly, the execution of the print job itself is suspended.

FIG. 15 is a diagram showing a setting screen of the operation panel 50 in the modified example. FIG. 16 is a flowchart showing the print control according to the modified example.

The user sets the print job for performing the color audit through the setting screen of the operation panel 50 shown in FIG. The user can select either the check buttons b1 and b2 on the setting screen. In the figure, the check button b2 "allows printing before the reading accuracy stabilizes" (first mode) is selected. In this state, the first embodiment described above is executed. When the check button b2 is selected, the color difference variation permissible amount (permissible threshold value) can be further set in the input field b3. In the example of FIG. 15, “0.2” is set as ΔE00. By reducing the setting of the allowable threshold value, the accuracy of the color audit can be prioritized, and by increasing the setting of the allowable threshold value, the productivity can be prioritized.

In the process of the modification 1 described below, when the check button b1 "printing is not allowed until the reading accuracy is stable" (second mode (hold setting)) is selected and the second mode is executed. Applies to. In addition, when the check button b1 is selected and the process of the modification 1 is applied, when the hold of the execution of the print job is released, the process of the first embodiment is continuously performed thereafter. .. The value in the input field b3 is applied as the allowable amount of color difference fluctuation at that time. The lower limit of the input field b3 is, for example, ΔE00 = 0.1.

(S601)
First, as in step S101, the control unit 10 includes a print job in which the print job received via the communication interface 90 or the like executes reading by the reading unit 60, that is, information on spot colors to be subject to color auditing. Determine if it is a printed job. If it is a print job for executing image reading (S601: YES), the process proceeds to step S602. On the other hand, if it is not a print job for executing image reading (S601: NO), the process proceeds to step S110 (FIG. 9).

(S602)
In this process, the temperature transition data of the reading unit 60 is acquired from the storage unit 20.

(S603)
The control unit 10 determines whether or not the temperature of the reading unit 60 is stable from the temperature transition data acquired in step S602. Specifically, the amount of temperature change per hour is calculated from the current temperature and the temperature one minute before, and it is determined whether or not this exceeds a predetermined value, for example, 2 (° C./min). If the value exceeds the predetermined value and is not stable (S603: NO), the process proceeds to step S604. On the other hand, if it is 2 (° C./min) or less and stable (S603: YES), the process proceeds to step S102 (FIG. 9), and printing is executed.

It should be noted that this predetermined value is predetermined so that the amount of color difference fluctuation per unit time is equal to or less than the reference value. Further, this predetermined value may also be set by the user through the operation panel 50.

(S604)
In this process, the execution of the print job received in step S601 is suspended. This hold continues until it is determined in step S603 that the temperature has stabilized (S603: YES).

As described above, in the modified example 1, the first and second modes can be selected from the setting screen and the like shown in FIG. 15, and when the second mode is selected, the temperature change of the reading unit 60 is stable. Holds print job execution until By doing so, it is possible to prevent the shading correction from being executed with high frequency even though the print job is started.

(Modification 2)
In the first embodiment, as shown in FIGS. 12 and 14, in steps S315 and S325, the execution of the next shading correction is controlled to start at the time Ta, but the time Ta is not limited to this. You may shift to a slightly earlier time. For example, the time at which the execution of the next shading correction is started is shifted forward to the transfer end time of the paper Sn-1 conveyed immediately before, and the transfer time of the paper Sn is also shifted forward by the same amount. As a result, the processing time is shortened as a whole and the productivity is improved.

(Modification 3)
Further, in the first embodiment, shading correction has been described as an example of "calibration" for determining the timing according to the temperature change of the reading unit, but the timing is not limited to this and the timing is determined for other calibrations. You may do so. For example, the calibration of the reading unit using the colorimeter 70 may be the target for determining the timing.

(Modification example 4)
A plurality of types of shading corrections may be applied as shading corrections. For example, the shading correction performed first after the start of execution of the print job is different from the shading correction performed the second and subsequent times.

FIG. 17 is a diagram schematically showing the processing of the modified example 4. In the figure, the shading correction A is executed during the time 8 to 15 (sec), and a different type of shading correction B is executed during the time 21 to 24 (sec).

Here, the shading correction B is the shading correction described in the first embodiment using the white surface c2 of the rotating body 691. The shading correction A is for cleaning the original glass in addition to the shading correction B. Specifically, the original glass 64 is first cleaned with the cleaning brush 693 of the rotating body 691 for several seconds, and then the shading correction is performed. In the fourth modification, the shading correction A is executed only at the first time (first time) after the print job is started, and the shading correction B is executed after the second time. Shading correction A, which has a long execution time, is performed during the time until the first paper S, which can secure a relatively long time, reaches the reading position P1, and shading correction B, which has a short execution time, is performed between papers whose time is difficult to secure. .. By doing so, it is possible to prevent the fluctuation of the color difference from exceeding a predetermined allowable amount, and it is possible to maintain the productivity.

The configuration of the image forming system described above is not limited to the above configuration, as the main configuration has been described in explaining the features of the above-described embodiment and modification. Moreover, the configuration provided in a general image forming system is not excluded.

Further, the program for operating the image forming system may be provided by a computer-readable recording medium such as a USB memory, a flexible disk, or a CD-ROM, or may be provided online via a network such as the Internet. .. In this case, the program recorded on the computer-readable recording medium is usually transferred to a memory, a storage, or the like and stored. Further, this program may be provided as a single application software, or may be incorporated into the software of each device as a function of the image forming system.

100 Image formation system A1 Image formation device A2 First post-processing device A3 Second post-processing device 10 Control unit 20 Storage unit 30 Image formation unit 31 Intermediate transfer belt 32 Photoreceptor drum 33 Development unit 34 Writing unit 35 Secondary transfer unit 36 Fixing unit 40 Paper feed transport unit 41 Paper feed tray 42, 42a to 42d Transport path 43 Transport roller 43a Resist roller 46 Paper discharge tray 50 Operation panel 60 Reading unit 61 Sensor array 62 Optical system 63 Light source 64 Original glass 65 Temperature sensor 66 Housing 69 Reading calibration unit 691 Rotating body c1 Reading surface c2 White surface c3 Black surface 692 Rotating shaft 693 Cleaning brush P1 Reading position 70 Colorimeter 80 Post-processing unit 90 Communication interface

Claims (9)

A transport unit that transports paper and
An image forming unit that forms an image on the paper conveyed by the conveying unit,
A reading unit provided on the downstream side in the transport direction from the image forming unit and reading an image on paper formed by the image forming unit.
A temperature sensor that detects the temperature of the CCD substrate of the reading unit, and
A proofreading unit that calibrates the reading unit and
A storage unit that stores temperature characteristics indicating the amount of change in the color difference of the reading unit with respect to the temperature change amount of the reading unit.
During execution of a continuous printing job for forming an image on a plurality of sheets of continuously conveyed sheets, the proofreading unit calibrates the reading unit based on the temperature characteristics and the amount of temperature change of the reading unit. The control unit that determines the timing and
An image forming system comprising. The control unit determines the amount of change in color difference from the previous calibration based on the temperature change amount calculated from the temperature of the reading unit and the current temperature when the calibration was executed immediately before, and the temperature characteristics. The image forming system according to claim 1, wherein the timing at which the permissible threshold value is reached is calculated, and the calculated timing is determined as the timing at which the calibration is next executed. The image forming system according to claim 2, further comprising a setting reception unit that accepts the setting of the allowable threshold value by the user. The setting receiving unit can accept a hold setting for suspending execution of a continuous printing job using the reading unit.
The image according to claim 3, wherein the control unit suspends execution of the continuous printing job until the temperature change amount per unit time of the reading unit becomes a predetermined value or less when the hold setting is accepted. Forming system. Based on the setting of the continuous printing job, the control unit determines whether or not the determined proofing execution timing is during the transfer of any of a plurality of sheets, and the transfer of the sheets. If it is determined that the paper is in the middle, the execution timing is changed between the papers immediately before the paper, and / or the transfer timing of the paper is delayed, according to any one of claims 1 to 4. The image forming system described. The calibration unit includes a reference plate for calibration.
The image forming system according to any one of claims 1 to 5, wherein the calibration is a shading correction using the reference plate, and the shading correction includes different types of shading correction. When the print setting of the continuous printing job is set to read the reading unit, the control unit performs the continuous printing when the amount of temperature change per unit time of the reading unit exceeds a predetermined value. Any one of claims 1 to 3, claim 5, and claim 6 that suspends the execution of the print job and starts the execution of the suspended continuous print job when the value falls below the predetermined value. The image forming system according to one. A control program for an image forming system provided on the downstream side of the image forming section in the transport direction and including a reading section for reading an image on paper formed by the image forming section and a proofreading section for proofreading the reading section. And
A step to start execution of a continuous printing job that forms an image on multiple sheets of continuously conveyed paper, and
A step of reading from the storage unit a temperature characteristic indicating the amount of change in the color difference of the reading unit with respect to the amount of temperature change of the reading unit.
The timing for calibrating the reading unit by the calibration unit is determined from the read temperature characteristics and the amount of temperature change of the reading unit calculated from the detection temperature of the temperature sensor that measures the temperature of the CCD substrate of the reading unit. Steps to do and
A control program for causing the image forming system to execute the step of executing the proof during the execution of the continuous printing job according to the determined timing. In the decision step
Based on the temperature change amount calculated from the temperature of the reading unit and the current temperature when the calibration was executed immediately before, and the temperature characteristics, the variation amount of the color difference from the immediately preceding calibration becomes a predetermined allowable threshold value. The control program according to claim 8, wherein the timing of reaching is calculated, and the calculated timing is determined as the timing for executing the calibration next.