JP2020046517A - Measuring device, image forming device, and image formation system - Google Patents

Abstract

To provide a measuring device capable of reducing the possibility foreign matter such as paper powder may affect the measurement results.SOLUTION: A measuring device (400) includes: a first transport path (430) for transporting a sheet discharged from image forming device toward a sheet handling unit connected to the measuring device, and a second transport path (431) branched from the first transport path. The second transport path has measuring means (700) disposed for measuring the image pattern of a sheet discharged from the image forming device. Blowing means (801) blows the air to the second transport path between a communication part (P2) where the second transport path communicates with the first transport path and a measuring position (P1) where the measuring means measures the image pattern of the sheet.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a measuring device for measuring an image pattern on a sheet, an image forming device for forming an image on a sheet, and an image forming system including the measuring device and the image forming device.

  2. Description of the Related Art Conventionally, there is known a technique in which a sensor for measuring an image pattern formed on a sheet is mounted on an image forming apparatus or an image forming system, and an image forming condition is changed based on a measurement result of the sensor. In Patent Document 1, a sensor for measuring the spectral reflectance of a patch image on a sheet is provided inside the image forming apparatus, and the process conditions of the electrophotographic unit (for example, a tone correction table or A technique for changing the values of various bias voltages) is described. Patent Document 2 discloses a technique in which an image of a sheet on which a chart image including vertical and horizontal reference lines is printed is read by a sensor, and the position and shape of an image formed by an image forming unit are corrected.

JP-A-2004-86013 JP 2017-228165 A

  However, in the configuration of Patent Literature 1 or 2, the sensor is disposed on the conveyance path of the sheet as a product, and there is a concern that a measurement defect or a decrease in measurement accuracy may occur due to foreign matter such as paper dust generated from the sheet. Was. For example, in the configuration of Patent Literature 2, when a foreign object appears in a read image and a linear image defect (streak image) occurs, the paper shape may be erroneously recognized, and the position or shape of the image may not be properly corrected. there were.

  Therefore, an object of the present invention is to provide a measuring device, an image forming apparatus, and an image forming system that can reduce the possibility that foreign matter such as paper dust affects the measurement result.

  One embodiment of the present invention is a measuring device connected to an image forming apparatus that forms an image on a sheet, and directs a sheet discharged from the image forming device to a sheet processing device connected to the measuring device. A first conveying path for conveying, a second conveying path branched from the first conveying path, and a measuring unit arranged on the second conveying path and measuring an image pattern of a sheet discharged from the image forming apparatus; A communication unit that connects the second transport path to the first transport path; and a blower that blows the second transport path between a measurement position where the measurement unit measures an image pattern of a sheet. A measuring device characterized by the following.

  Another aspect of the present invention is an image forming apparatus including an image forming unit that forms an image on a sheet, and discharges the sheet on which an image is formed by the image forming unit from the image forming apparatus. A first transport path for transporting toward the discharge unit, a second transport path branched from the first transport path, and an image pattern arranged on the second transport path and formed on the sheet by the image forming unit are measured. Between the measurement unit, the communication unit where the second conveyance path communicates with the first conveyance path, and the measurement position where the measurement unit measures the image pattern of the sheet. And an image forming apparatus.

  ADVANTAGE OF THE INVENTION According to this invention, the possibility that a foreign substance, such as paper powder, will affect a measurement result can be reduced.

1 is a schematic diagram of an image forming system according to an embodiment of the present disclosure. The schematic diagram of an adjustment unit. FIG. 2 is a block diagram illustrating a control configuration of the image forming system. The schematic diagram of a color sensor. FIG. 4 is a diagram for explaining a data structure of an ICC profile. FIG. 2 is a conceptual diagram for explaining the role of a color management module. Schematic diagram of the front and back register. The schematic diagram (a, b) which shows the pattern image for front and back register. The figure which shows the content of a sheet library. FIG. 9 is an image diagram showing a display screen of a sheet library (a) and a selection screen (b) of a parameter correction method. 5 is a flowchart illustrating a control example of the image forming system. 5A and 5B are schematic diagrams for explaining a sheet conveying operation in a normal job (a, b). FIGS. 4A and 4B are schematic diagrams (a, b) for explaining a sheet conveying operation in a colorimetric job. FIGS. 3A to 3D are schematic diagrams (a to d) illustrating a sheet conveying operation in a front and back register job. FIG. 3 is a perspective view of a paper dust removing unit according to the embodiment. The schematic diagram which shows the internal structure of the paper dust removal part which concerns on this embodiment. FIG. 4 is a schematic diagram illustrating a relationship between a paper dust removing unit and a guide shape according to the embodiment. The schematic diagram which shows the adjustment unit of a modification. The schematic diagram which shows the relationship between the paper dust removal part of a modification, and a guide shape.

  Hereinafter, typical embodiments for implementing the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic diagram illustrating an image forming system 100S according to the present embodiment. The image forming system 100S includes the image forming apparatus 100, an adjustment unit 400, and a finisher 600. The image forming apparatus 100 is the image forming apparatus of the present embodiment, the adjustment unit 400 is the measuring apparatus of the present embodiment, and the finisher 600 is the sheet processing apparatus of the present embodiment.

  The housing 101 of the image forming apparatus 100 has an image forming engine 102 mounted thereon, and a control board storage unit that houses a printer controller 103 described below that controls the operation of the image forming system 100S including the image forming apparatus 100. I have. The image forming engine 102 according to the present exemplary embodiment includes an optical processing mechanism and a fixing processing mechanism that form an image on a recording material by an electrophotographic process, and a feeding processing mechanism and a conveyance that feed and transport a sheet 1 used as a recording material. And a processing mechanism. As the recording material, paper such as plain paper or cardboard, coated paper such as coated paper or embossed paper, sheet material such as plastic film or cloth can be used.

  The optical processing mechanism includes stations 120, 121, 122, 123 for forming toner images of respective colors of yellow, magenta, cyan, and black, and an intermediate transfer belt 106. In each of the stations 120 to 123, the primary charger 111 charges the surface of the photosensitive drum 105, which is a drum-shaped photosensitive member. The laser scanner unit 107 performs an exposure process on the photosensitive drum 105 based on a command signal generated based on the image data and transmitted to the laser scanner unit 107. The laser scanner unit 107 has a laser driver that turns on and off a laser beam emitted from a semiconductor laser (not shown). The laser mirror 107 distributes the laser beam from the semiconductor laser in the main scanning direction by a rotating polygon mirror, and reflects the laser beam. Through the photosensitive drum 105. As a result, an electrostatic latent image corresponding to the image data is formed on the surface of the photosensitive drum 105.

  The developing device 112 contains a developer containing a toner therein, and supplies charged toner particles to the photosensitive drum 105. When the toner particles adhere to the drum surface according to the surface potential distribution, the electrostatic latent image carried on the photosensitive drum 105 is visualized as a toner image. The toner image carried on the photosensitive drum 105 is transferred (primary transfer) to the intermediate transfer belt 106 to which a voltage having a polarity opposite to the normal charge polarity of the toner is applied. When a color image is formed, the toner images formed by the four stations 120 to 123 are multiplex-transferred on the intermediate transfer belt 106 so as to overlap each other, so that a full-color toner image is formed on the belt. On the other hand, the feed processing mechanism feeds the sheets 1 one by one toward the transfer roller 114 from the storage 113 inserted so as to be able to be pulled out to the housing 101 of the image forming apparatus 100. The toner image carried on the intermediate transfer belt 106, which is an intermediate transfer member, is transferred (secondarily transferred) to the sheet 1 by the transfer roller 114.

  Around the intermediate transfer belt 106, an image formation start position detection sensor 115 for determining a print start position when performing image formation, a feed timing sensor 116 for timing sheet 1 feed, and a density sensor 117. Is arranged. The density sensor 117 measures the density of the patch image carried on the intermediate transfer belt 106. The printer controller adjusts the operation conditions of the optical processing mechanism (for example, the setting of the charging target potential of the primary charger 111 and the setting of the bias voltage of the developing device 112) based on the detection result of the density sensor 117.

  The fixing processing mechanism of the present embodiment includes a first fixing device 150 and a second fixing device 160. The first fixing device 150 includes a fixing roller 151 for applying heat to the sheet 1, a pressure belt 152 for pressing the sheet 1 against the fixing roller 151, and a second sensor that detects completion of the fixing process by the first fixing device 150. 1 includes a post-fixing sensor 153. Each roller including the fixing roller 151 is a hollow roller and has a heater inside. The first fixing device 150 applies heat and pressure to the toner image on the sheet while nipping and conveying the sheet 1 between the fixing roller 151 and the pressure belt 152, which are a pair of rotating members. As a result, the toner particles are melted and then fixed, whereby the image is fixed on the sheet 1.

  The second fixing device 160 is disposed downstream of the first fixing device 150 in the transport path of the sheet 1. The second fixing device 160 has a function of increasing the glossiness of the image on which the fixing process has been performed by the first fixing device 150 and securing the fixability of the image to the sheet 1. Similarly to the first fixing device 150, the second fixing device 160 includes a fixing roller 161 and a pressure roller 162 as a rotating body pair that heats and presses while conveying the sheet 1, and the completion of the fixing process by the second fixing device 160. And a second post-fixing sensor 163 for detecting the

  Note that, depending on the type of the sheet 1, it may not be necessary to pass the sheet through the second fixing device 160. In such a case, the image forming apparatus 100 has a bypass conveyance path 130 for discharging the sheet 1 without passing through the second fixing device 160 for the purpose of reducing energy consumption. The sheet 1 sent from the first fixing device 150 is guided to either the second fixing device 160 or the bypass conveyance path 130 by the first switching flap 131.

  The sheet 1 that has passed through the second fixing device 160 or the bypass conveyance path 130 is guided to either the discharge conveyance path 139 or the reverse conveyance path 135 by the second switching flap 132. The position of the sheet 1 conveyed into the reversing conveyance path 135 is detected by the reversing sensor 137, and the front and rear ends of the sheet 1 in the sheet conveyance direction are exchanged by the switchback operation performed by the reversing unit 136. In the case of double-sided printing, the sheet 1 on which an image is formed on the first surface is conveyed again to the transfer roller 114 via the re-conveying path 138 with the leading and trailing ends switched by the reversing unit 136, and An image is formed on the surface. The sheet 1 on which the image formation for one-sided printing has been completed or the sheet 1 on which the image formation on the second side has been completed for double-sided printing is discharged to the outside of the image forming apparatus 100 by a discharge roller 139a (discharge unit) provided in a discharge conveyance path 139. Is discharged. A switching flap 134 that guides the sheet 1 switched back by the reversing unit 136 toward the discharge conveyance path 139 is provided between the reverse conveyance path 135 and the discharge conveyance path 139, and is discharged from the image forming apparatus. The front and back of the sheet 1 can be selected. Note that an image reading device 190 that reads image information from a document is installed above the image forming apparatus 100.

  As shown in FIG. 3, the image forming apparatus 100 includes a printer controller 103 as a control unit that controls the operation of the image forming system 100S. The printer controller 103 is a control board on which at least one processor and a memory 304 are mounted. The memory 304 includes a temporary storage medium and a non-transitory storage medium, serves as a storage location for programs and data, and serves as a work space when the processor executes the programs. Further, the printer controller 103 has a functional unit (for example, a profile creation unit 301 and a CMM (color management module) 305) for exhibiting functions described below. These functional units may be individually implemented as independent hardware such as an ASIC, or may be implemented as software as functional units of a program executed by a central processing unit (CPU) of the printer controller 103.

  The engine control unit 312 causes the image forming engine 102 to perform the above-described image forming operation based on a command signal from the printer controller 103 to form an image on a sheet. For example, based on detection signals from the first post-fixing sensor 153, the second post-fixing sensor 163, and the reversing sensor 137, the engine control unit 312 includes a conveying motor 311 that drives a roller that conveys the sheet, the first switching flap 131, The operation of the second switching flap 132 is controlled.

  The image forming apparatus 100 is provided with an operation unit 180 serving as a user interface of the image forming system 100S (see also FIG. 1). The operation unit 180 includes a display as display means for displaying information to a user. The operation unit 180 includes, for example, physical keys such as a numeric keypad and a print execution button, and a touch panel function of a display as input means that allows a user to input commands and data to the image forming system 100S. By operating the operation unit 180, the user can input information representing sheet attributes such as the name, basis weight, and presence / absence of surface treatment of a sheet set in a storage 113 to the printer controller 103. The input sheet attributes are registered in the sheet library 900 stored in the memory 304.

  The printer controller 103 is connected to an external wired or wireless communication network via an external interface (I / F) 309, and can communicate with an external computer. The printer controller 103 is also connected to a control circuit of a device (in the present embodiment, the adjustment unit 400 and the finisher 600) that is connected to the image forming apparatus 100 and configures the image forming system 100S. The printer controller 103 communicates with these devices to coordinate operations of the image forming apparatus 100 and each device. The control configuration of the adjustment unit 400 will be described later.

(Adjustment unit)
Next, the adjustment unit 400, which is the measurement device of the present embodiment, will be described. In the image forming system 100S of FIG. 1, the adjustment unit 400 is installed between the image forming apparatus 100 and the finisher 600 in the horizontal direction (left and right directions in the figure). That is, the upstream device of the adjustment unit 400 in this embodiment is the image forming apparatus 100, and the downstream device of the adjustment unit 40 is the finisher 600. The finisher 600 has a processing unit 601 that performs processing such as binding processing and saddle processing on sheets, and performs image formation on the processed sheet bundle (if processing is not necessary, a sheet received from an upstream apparatus). It is discharged as a product of the system 100S.

  The devices connected upstream and downstream of the adjustment unit 400 change depending on the configuration of the image forming system 100S. For example, the adjustment unit 400 is not always directly connected to the image forming apparatus 100, and an intermediate unit is disposed between the image forming apparatus 100 and the adjustment unit 400, and the adjustment unit 400 receives a sheet from the intermediate unit. It may be configured. As an example of the intermediate unit, there is an apparatus that performs a coating process of attaching a transparent toner to an image surface of an image-formed sheet to impart gloss. Further, a sheet processing apparatus other than the finisher 600 may be connected to the downstream side of the adjustment unit 400 in some cases. Examples of such a sheet processing apparatus include an inserter that inserts a cover sheet into a sheet bundle, a trimmer that cuts and aligns the edges of the bound sheet bundle, and a cart that accommodates a large amount of products. There is a movable stacker.

  As shown in FIG. 2, the adjustment unit 400 includes a color sensor 500 and a front and back register 700, both of which are examples of a measurement unit, a through path 430 and a detection path 431 that constitute a sheet conveyance path in the adjustment unit, and a paper dust. And a removing unit 800. The through path 430 is a first transport path of the present embodiment, and the detection path 431 is a second transport path of the present embodiment.

  The through path 430 is a conveyance path that receives a sheet discharged from the image forming apparatus and conveys the sheet toward the finisher, and extends in a substantially horizontal direction. In the through path 430, a first roller 401, a second roller 402, a third roller 403, and a fourth roller 404 are arranged in this order from upstream to downstream in the sheet conveying direction.

  The detection path 431 is a path in which the color sensor 500 and the front and back register 700 described later are arranged, and is formed so as to bypass below the through path 430. That is, the detection path 431 includes a descending portion 431 a that branches downward from the through path 430 and extends downward, a horizontal portion 431 b that extends substantially in the horizontal direction, and an ascending portion 431 c that extends upward from the horizontal portion 431 b and joins the through path 430. . Therefore, the detection path 431 has two portions: a branch portion that branches from the through path 430 between the first roller 401 and the second roller 402, and a junction portion that joins the through path 430 on the upstream side of the third roller 403. It communicates with the through path 430. A switching flap 421, which is a guide member capable of switching the sheet conveyance path between the through path 430 and the detection path 431, is disposed at a branch of the detection path 431 from the through path 430. In the detection path 431, conveyance rollers 405a to 414 for conveying a sheet are arranged at a plurality of positions along the sheet conveyance direction in the detection path 431.

  The color sensor 500 and the front / back register 700 are arranged in sections where the horizontal portion 431b and the ascending portion 431c extend linearly when viewed from the width direction. The ascending portion 431c is inclined so as to move away from the side of the adjustment unit 400 on the finisher side (the left side in the drawing) as it goes upward, so as to secure a straight section as long as possible. Further, the paper dust removing unit 800 has a function of preventing the paper dust generated in the through path 430 from entering the front and back register 700 by forming an air curtain that crosses the detection path 431. The detailed configuration of the paper dust removing unit 800 will be described later.

  As shown in FIG. 3, the operation of the adjustment unit 400 is controlled by a control unit 451 mounted on the adjustment unit 400. The control unit 451 controls the transport motor 452 that drives the transport rollers and the flap switching motor 454 that switches the positions of the switching flap 421 and the second flap 422 based on the detection signal of the transport path sensor 453 disposed on each transport path in the adjustment unit. Control the operation of. The control unit 451 controls the operation of the fan (paper dust removing fan 801) of the paper dust removing unit 800 based on a command received from the printer controller 103 of the image forming apparatus 100 via the communication unit 450. In addition, the control unit 451 instructs the color sensor 500 and the image sensors (701, 702) of the front and back register 700 to execute measurement based on a command from the printer controller 103. The measurement result of the color sensor 500 or the image sensor (701, 702) is transmitted to the printer controller 103 via the communication unit 450 after the image processing unit 460 performs image processing as necessary.

<1. Color Sensor>
Hereinafter, the structure of the color sensor 500, which is the first measurement unit included in the adjustment unit 400, and color management using the color sensor 500 will be described. FIG. 4 is a schematic diagram illustrating the color sensor 500 according to the present embodiment. The color sensor 500 includes a white LED 501 that is a light source, a line sensor 503 that detects light intensity, and an optical system that irradiates the sheet with light from the light source and guides reflected light from the sheet to the line sensor 503. It is a sensor unit. The white LED 501 irradiates the patch image 520 on the sheet 1 with light having a continuous spectrum. The diffraction grating 502 disperses the light reflected by the patch image 520 for each wavelength. The line sensor 503 is configured by imaging elements 503-1,..., 503-n of n pixels, and measures the intensity of light decomposed by the diffraction grating 502 for each wavelength.

  The wavelength region that can be detected by the line sensor 503 substantially covers the entire visible light region, and is set, for example, in the range of 380 nm to 720 nm. , 503-n of the line sensor 503 can be CMOS sensors. In the illustrated configuration example, a lens 506 that condenses the reflection terms from the patch image 520 on the diffraction grating 502 is arranged.

  The detection signal of the line sensor 503 is processed by the calculation unit 504 mounted on the color sensor 500, and the calculation result is stored in the memory 505. The calculation unit 504 includes, for example, a spectral calculation unit that calculates a spectral reflectance of each patch image 520 by performing a spectral calculation from a light intensity value.

(Color management system)
A method for feeding back a measurement result of the color sensor 500 to the image forming apparatus 100 and managing colors will be described. In the present embodiment, an ICC (International Color Consortium) profile that has recently been accepted in the market is used as a profile that realizes excellent color reproducibility. However, another color management system may be adopted instead of the ICC profile. For example, it is possible to use a CRD (Color Rendering Dictionary) adopted in PostScript (registered trademark) proposed by Adobe and a color separation table mounted in Adobe Photoshop (registered trademark). Also, a CMYK simulation which is a function of ColorWise (registered trademark) of EFI, which maintains black plate information, can be used.

  FIG. 6 is a conceptual diagram for explaining color management by a CMM (color management module). The image data input to the image forming apparatus 100 does not always adopt the expression of colors in the L * a * b * color space, and various data formats (color system) such as RGB, CMYK, and CIE XYZ. Can be expressed as Further, even between image data having a common data format, the perceived color of the original image to be reproduced by the image forming apparatus 100 differs depending on the characteristics of the input device (for example, by setting the gamma value and the color temperature of the monitor). May be.

  Therefore, the CMM converts the input image data into L * a * b * data once expressed in a device-independent color space (in the present embodiment, the CIE L * a * b * color space). Then, the CMM generates a command (CMYK signal) for causing the image forming engine to form an image from the L * 'a *' b * 'data obtained by performing necessary correction on the L * a * b * data. At this time, the input ICC profile is used for conversion from the color system of the input device to the L * a * b * color space. The output ICC profile is used for conversion from the L * a * b * color space to the color space handled by the image forming engine (the space of values that the CMYK signals can take). In this embodiment, CIE L * a * b * is used as a device-independent color space, but another color space (for example, CIE1931 XYZ color space) may be used instead.

  The CMYK signal specifies the exposure level of the laser scanner 107 of each of the stations 120 to 123 for yellow, magenta, cyan, and black. That is, the value of the CMYK signal corresponds to the toner density level of each pixel of the monochrome image formed by each of the stations 120 to 123. The CMYK signal is transmitted from the printer controller 103 to the engine control unit 312 and then input to the laser scanner unit 107 as a video signal.

(Measurement by color sensor)
Since the image forming system 100S of the present embodiment includes the adjustment unit 400 on which the color sensor 500 is mounted, it is possible to create its own output ICC profile. The output ICC profile is a color conversion profile that represents a correspondence between the CMYK signal to the image forming engine 102 and the color of an image actually formed on a sheet by the image forming engine 102.

  When creating an output ICC profile of the image forming apparatus 100, first, in the image forming apparatus 100, a patch image is formed on a sheet in a pattern designated in advance, and an image pattern for color measurement is formed on the sheet. The sheet on which the image pattern is formed is sent to the adjustment unit 400, and the color sensor 500 measures the spectral reflectance. That is, the light emitted from the white LED 501 and reflected by the patch image in the image pattern is dispersed by the diffraction grating 502, and the line sensor 503 measures the light intensity for each wavelength.

(Specification of color space coordinates of patch image)
Next, from the spectral reflectance read by the color sensor 500, coordinates representing the color of each patch in a device-independent color space (here, an L * a * b * color space defined by the CIE) are calculated. How to do it. The coordinates in the L * a * b * color space can be calculated from the spectral reflectance by a procedure based on ISO 13655, for example, as described below.

a. The spectral reflectance R (λ) of the sample is determined. (Λ: 380 nm to 780 nm)
b. A color matching function x (λ), y (λ), z (λ) and a standard light spectral distribution SD50 (λ) are prepared. The color matching function is defined by JIS Z8701. SD50 (λ) is defined in JIS Z8720 and is also called auxiliary standard illuminant D50. In addition, x (λ), y (λ), and z (λ) are usually represented by notations with overlines, but are omitted in the following description.
c. The spectral reflectance R (λ), the color matching functions x (λ), y (λ), z (λ) and the standard light spectral distribution SD50 (λ) are multiplied for each wavelength.
R (λ) × SD50 (λ) × x (λ)
R (λ) × SD50 (λ) × y (λ)
R (λ) × SD50 (λ) × z (λ)
d. The product of (c) is integrated over the entire wavelength range.
{R (λ) × SD50 (λ) × x (λ)}
{R (λ) × SD50 (λ) × y (λ)}
{R (λ) × SD50 (λ) × z (λ)}
e. The integrated value of the product of the color matching function y (λ) and the standard light spectral distribution SD50 (λ) is obtained.
{SD50 (λ) × y (λ)}
f. Calculate the coordinates in the XYZ color space.
X = 100 × {SD50 (λ) × y (λ)} / {R (λ) × SD50 (λ) × x (λ)}
Y = 100 × {SD50 (λ) × y (λ)} / {R (λ) × SD50 (λ) × y (λ)}
Z = 100 × {SD50 (λ) × y (λ)} / {R (λ) × SD50 (λ) × z (λ)}
g. The XYZ coordinates obtained in (f) are converted to an L * a * b * color space.
L * = 116 × (Y / Yn) ＾ (1/3) -16
a * = 500 {(X / Xn)} (1/3)-(Y / Yn) {(1/3)}
b * = 200 {(Y / Yn)} (1/3)-(Z / Zn) {(1/3)}

In (g), Xn, Yn, and Zn are values (standard light tristimulus values) representing the coordinates of the reference white point. The above is the conversion formula when Y / Yn ≧ 0.008856, and in the region of Y / Yn <0.008856, the following is replaced.
(X / Xn) ＾ (1/3) → 7.78 (X / Xn) ＾ (1/3) +16/116
(Y / Yn) ＾ (1/3) → 7.78 (Y / Yn) ＾ (1/3) +16/116
(Z / Zn) ＾ (1/3) → 7.78 (Z / Zn) ＾ (1/3) +16/116

(Profile creation processing)
Next, the contents of a profile creation process in which the image forming apparatus 100 creates an ICC profile will be described. The profile creation process can be executed at an arbitrary timing by the user operating the operation unit 180 to issue an explicit instruction. For example, when parts are replaced by a customer engineer, before executing an image forming job requiring high color reproducibility, and further, when it is desired to know the color of the final output at the design concept stage, a profile is created. Processing may be performed.

  In FIG. 3, when an operation for creating an ICC profile is performed on the operation unit 180, a signal instructing creation of a profile is input to the profile creation unit 301 of the printer controller 103. The profile creation unit 301 transmits a CMYK signal for outputting a 928 patch test form (CMYK color chart) specified in ISO 12642 to the engine control unit 312 without performing color conversion based on the output ICC profile. That is, in the present embodiment, a test form specified in ISO 12642 is used as an image pattern for performing color management. In parallel with the transmission of the CMYK signal, the profile creation unit 301 sends an instruction for performing measurement using the color sensor 500 to the adjustment unit 400.

  The image forming apparatus 100 performs an image forming operation based on the CMYK signal input to the engine control unit 312, and forms a test form on a sheet. The sheet on which the test form is formed is conveyed to the adjustment unit 400, and the color of the test form is measured by the color sensor 500. The spectral reflectance data of each of the 928 patches measured by the color sensor 500 is notified to the Lab operation unit 303 of the printer controller 103, and is converted into data of the L * a * b * color space by the Lab operation unit 303. .

  The profile creating unit 301 creates an output ICC profile by associating the CMYK signal transmitted to the engine control unit 312 with the color measurement result of the color sensor 500. Further, the profile creation unit 301 replaces the current output ICC profile stored in the memory 304 with a newly created output ICC profile.

  The output ICC profile has, for example, a structure as shown in FIG. 5, and includes a header, a tag, and data thereof. The profile creation unit 301 converts a CMYK → L * a * b * conversion table (A2Bx tag) based on the CMYK signal used for outputting the test form and the L * a * b * value obtained from the color measurement result. Create Also, based on this conversion table, an inverse conversion table (B2Ax tag) of L * a * b * → CMYK is created. As the tags representing other data, a white point (wtpt), a tag (gamt) describing whether a certain color is inside or outside the color gamut of a hard copy output by the image forming apparatus 100, and the like are also described in the output ICC profile. .

  When the execution command of the profile creation process is input via the external I / F 309, the ICC profile created by the profile creation unit 301 may be transmitted to the external device that has issued the execution command. In this case, it is possible for the user to perform color conversion in an application corresponding to the ICC profile on an external device.

As an index for color matching accuracy and color stability, for example, a color matching accuracy standard described in ISO 12647-7 (IT8.7 / 4 (ISO 12642: 1617 patch) [4.2.2]) ΔE is specified to be 4.0 on average. Further, the reproducibility [4.2.3], which is a standard for stability, stipulates that ΔE of each patch is 1.5 or less. In order to satisfy the above specifications, the detection accuracy of the color sensor 500 is desirably ΔE1.0 or less. Here, ΔE is a parameter represented by the following equation, and means a three-dimensional distance between two points (L1, a1, b1) (L2, a2, b2) in the L * a * b * color space. .
ΔE = ((L1−L2) ＾ 2 + (a1−a2) ＾ 2 + (b1−b2) ＾ 2) ＾ (1/2)

(Color conversion processing)
Next, a color conversion process performed on input image data when an image forming job instructing the image forming apparatus 100 to form an image is input will be described. In the block diagram shown in FIG. 3, image data received by the printer controller 103 via the external I / F 309 is input to the CMM 305. In normal color printing, image data is often represented by standard printing CMYK signal values such as RGB values and JapanColor. In this case, the input side color space conversion unit 306 of the CMM 305 performs color conversion of RGB → L * a * b * or CMYK → L * a * b * with reference to the input ICC profile stored in the memory 304. , The input image data is converted into L * a * b * data. The input ICC profile includes a one-dimensional LUT (look-up table) for controlling gamma of an input signal, a multi-order color LUT called direct mapping, and a one-dimensional LUT for controlling gamma of generated conversion data.

  The adjustment unit 307 of the CMM 305 performs necessary correction on the L * a * b * data in order to adjust the color of the product. An example of the correction processing includes GAMUT conversion for correcting a mismatch between the color gamut of the input device and the color gamut reproducible by the image forming apparatus 100. Another example is color conversion for adjusting a mismatch (also referred to as a mismatch in color temperature setting) between the light source type on the input side and the light source type when observing the product of the image forming apparatus 100. Still another example is a black character determination for determining a character part in a color image and converting the character part into a color suitable for the character color in order to improve the readability of the character in the product. Through these correction processes, L * a * b * data is converted into L * 'a *' b * 'data. The adjustment unit 307 of the CMM 305 also performs a correction process as needed to perform L * processing when input image data input via the external I / F 309 is expressed in the L * a * b * color space. Convert to 'a *' b * 'data.

  The output-side color space conversion unit 308 of the CMM 305 performs L * a * b * → CMYK color conversion with reference to the output ICC profile stored in the memory 304 to convert L * ′ a * ′ b * ′ data. Convert to CMYK signal. At this time, when the output ICC profile is updated by the profile creation unit 301, even if the L * 'a *' b * 'data is the same, the CMYK signal generated in the state before the update and the state after the update Will be different. That is, the output ICC profile as the image forming condition of the image forming apparatus 100 is changed according to the measurement result of the adjustment unit 400 which is the measuring apparatus of the present embodiment.

<2. Front and Back Register>
Next, the configuration and operation of the front and back register 700 (see FIG. 2), which is the second measuring means included in the adjustment unit 400, will be described. The front and back register 700 measures the sheet shape and the shape and positional relationship of the image pattern on the sheet. In order to obtain high-precision measurement results, it is necessary to average out shape variations and image position variations for each sheet. Therefore, a plurality of sheets are measured. Therefore, in this embodiment, a contact image sensor (CIS) is employed as a sensor unit for performing measurement. By using the CIS, measurement can be performed while conveying the sheet (instead of moving the sensor unit), and the time required for measurement can be reduced. Further, by using an image sensor of the same magnification optical system, the size of the apparatus can be reduced as compared with a reduction optical system (a so-called CCD system).

  As shown in FIG. 7, the front and back register 700 has a front surface CIS 701 and a back surface CIS 702. The front surface CIS 701 reads image information from the first surface 1a of the sheet 1, and the back surface CIS 702 reads image information from the second surface 1b (the surface opposite to the first surface 1a) of the sheet 1. The front CIS 701 and the back CIS 702 are arranged as close as possible (adjacent to each other with the transport roller 212 interposed therebetween in the illustrated configuration), and the pattern images formed on the front 1a and the back 1b of the sheet 1 are almost simultaneously. It is possible to read.

  The configuration of the front surface CIS 701 and the rear surface CIS 702 is common. That is, the CISs 701 and 702 include an LED array as a light source, a sensor array including an image sensor such as a CMOS, and a plurality of lenses (lens arrays) that form an image of reflected light from the sheet 1 on the sensor array. The LED array, the sensor array, and the lens array are arranged in the width direction across the entire length of the CISs 701 and 702 where image information can be read in the width direction orthogonal to the sheet conveyance direction in the front and back register 700. ing.

  The sheet 1 arriving at the front and back register 700 sequentially passes through the reading positions of the back CIS 702 and the front CIS 701 while being conveyed by the conveyance rollers 211, 212, and 213. The reading position of the back CIS 702 is a space between the transparent guide 704 and the black guide 706, and the reading position of the front CIS 701 is a space between the transparent guide 703 and the black guide 705. The black guides 705 and 706 are conveyance guides for guiding the sheet 1 and are members serving as backgrounds when the CISs 701 and 702 scan the sheet 1, and have a black contrast with the sheet 1. The transparent guides 703 and 704 are opposed to the opposed black guides 705 and 706 with a predetermined gap therebetween, and stabilize the position of the sheet 1 at the reading position in the depth of focus direction.

(Front and back register feedback)
Next, the measurement by the front and back register 700 and the feedback of the measurement result will be described. A sheet library 900 (see FIG. 3) held by the printer controller 103 in the memory 304 stores a list of sheets that can be used as a recording material by the image forming apparatus 100 with attributes such as length in the sub / main scanning direction and basis weight. This is the data stored in association with the information. Among the information included in the sheet library 900, the geometric adjustment amounts 901 and 902 are parameters for correcting the position and shape of an image when performing an image forming operation using the sheet.

  As shown in FIG. 10A, the contents of the sheet library 900 can be confirmed by displaying the library display screen 1001 on the operation unit 180. When the “print position adjustment” button 1002 on the library display screen 1001 is operated, a correction method selection screen 1003 shown in FIG. 10B is displayed. When the “manual adjustment” option 1004 is selected, the user can directly specify the values of the geometric adjustment amounts 901 and 902 by inputting a numerical value using a numeric keypad or the like. On the other hand, when the option 1005 of “Read test page and adjust” is selected, image forming apparatus 100 forms a pattern image for front and back registration, and front and back registration unit 700 of adjustment unit 400 performs measurement of the sheet. Thus, the geometric adjustment amounts 901 and 902 are automatically adjusted.

  In the front and back register processing according to this embodiment, as shown in FIGS. 8A and 8B, test patterns 820 in which square patches are arranged near four corners of the sheet surface are formed on both sides of the sheet 1. After the sheet 1 is fed from the sheet storage housing the sheet designated as the front and back register processing target, and the test pattern 820 is formed by the image forming engine 102, the sheet 1 is conveyed to the adjustment unit 400. . The front and back register 700 of the adjustment unit 400 reads a line image by the CIS 701 and 702 from the sheet 1 passing through the reading position while transporting the sheet 1 by the transport rollers 211, 212 and 213. Then, by linking the line images in the sub-scanning direction (the conveying direction of the sheet 1), the image data including the test pattern 820 on the sheet 1 and the sheet is synthesized.

The image processing unit 460 (see FIG. 3) of the adjustment unit 400 detects the contour of the sheet 1 and the test pattern 820 from the combined image data, and calculates the corner coordinates of the sheet 1 and the coordinates of each patch of the test pattern 820. Identify. The corner coordinates of the sheet 1 are the positions of four corners of the sheet 1 when the X axis is the main scanning direction (the width direction of the sheet 1) and the Y axis is the sub scanning direction, ｛(X ₀₁ , Y _{01) ~ (X 31, Y} 31), representing the _{(X 02, Y 02) ~} (X 32, Y 32)}. The corner coordinates of the sheet 1 include information on the sheet shape such as the long side length (A) and the short side length (B) of the sheet and the right angle of the corner. In addition, the coordinates of the test pattern 820 are the positions 特定 (X ₄₁ , Y ₄₁ ) to (X ₇₁ , Y ₇₁ ), (X ₄₂ , Y ₄₂ ) of the specific portion of the pattern image in the same coordinate system as the coordinates of the corners. ) To (X ₇₂ , Y ₇₂ )}. The coordinates of the test pattern 820 include information relating to the displacement of the image with respect to the sheet and the distortion of the image.

  The image processing unit 460 further calculates the geometric adjustment amount for the sheet 1 using the corner coordinates of the sheet 1 and the coordinates of the test pattern 820. Among the geometric adjustment amounts, the lead position is a parameter that defines the image position of the sheet 1 in the sub-scanning direction. The side position is a parameter that defines the image position of the sheet 1 in the main scanning direction. The main scanning magnification is a parameter that defines a magnification for enlarging or reducing image data in the main scanning direction. The sub-scanning magnification is a parameter that defines a magnification for enlarging or reducing image data in the sub-scanning direction. For these parameters, for example, assuming that the image shape is corrected, the distance from the test pattern 820 to the edge of the sheet (C to J in FIGS. 8A and 8B) is set in advance. Determined to be equal to the value.

  Here, the four parameters of the lead position, the side position, the main scanning magnification, and the sub-scanning magnification are described as the geometric adjustment amounts, but the image processing unit 460 may calculate other parameters. For example, a parameter for performing trapezoidal correction of an image or a parameter for defining a rotation angle of an image with respect to a sheet can be considered.

  The geometric adjustment amount calculated by the image processing unit 460 is sent to the printer controller 103 of the image forming apparatus 100 via the communication unit 450 and registered in the sheet library 900. When the image forming apparatus 100 executes an image forming job, the image shape correction unit 320 refers to the sheet library 900 and obtains sheet information 910, 911, 912,. get. Then, the image shape correction unit 320 corrects the image data based on the geometric adjustment amounts 901 and 902 of the acquired sheet information. Thereby, the displacement and distortion of the output image are reduced. That is, the geometric adjustment amounts 901 and 902 are another example of the image forming conditions that are changed based on the measurement result of the adjustment unit 400.

  Although the case where the test pattern 820 for front and back registration is formed based on an explicit instruction from the user has been described here, the test pattern 820 may be formed in other cases. For example, when an image forming job is input, as a preparatory operation before executing the job, a test pattern 820 is formed on the same sheet as that specified by the job to acquire a geometric adjustment amount. You may. In addition, during execution of an image forming job requiring a large number of products, calibration may be performed by automatically inserting a job for forming a test pattern 820 every time a predetermined number of products are output. .

(Control method)
In the image forming system 100S configured as described above, a method of controlling the sheet conveyance operation and the measurement operation in the adjustment unit 400 will be described with reference to the block diagram of FIG. 3 and the flowchart of FIG.

  In the following description, among the image forming jobs, a job that requests output of a product and does not require the adjustment unit 400 to measure an image pattern is referred to as a “normal job”. Among the image forming jobs, those in which the adjustment unit 400 measures an image pattern for performing color management by the color sensor 500 are referred to as “colorimetric jobs”. Further, among the image forming jobs, those in which the adjustment unit 400 measures the image patterns for performing the front and back registration by the CISs 701 and 702 of the front and back registration unit 700 are referred to as “front and back registration jobs”. Note that a normal job is input to the printer controller 103 when it is input from an external computer via the external I / F 309 or when the user instructs the start of a copying operation via the operation unit 180. As described above, the colorimetric job and the front / back register job may be executed by an explicit command from the user, or may be spontaneously executed by the image forming system 100S.

  At the start of the image forming job (S1), the printer controller 103 determines whether the job is a normal job, a colorimetric job, or a front / back register job (S2, S3). In the case of a normal job (S2: Y), members involved in sheet conveyance in the image forming apparatus 100 and the adjustment unit 400 wait at a default position (home position). In the case of the adjustment unit 400, the switching flap 421 is positioned at a position for guiding the sheet to the through path 430 (S4). That is, as shown in FIG. 12A, the switching flap 421 is held at the lower position. In the case of a normal job, the paper dust removing fan 801 (see FIG. 3) is energized to perform a blowing operation to the detection path 431 (S4).

  After the image forming apparatus 100 forms an image on a sheet according to the image data requested to be output by the image forming job (S5), the adjustment unit 400 receives the sheet (S6). Then, as shown in FIGS. 12A and 12B, the sheet 1 is sequentially passed through the first roller 401 to the fourth roller 404 and passes through the through path 430. Then, the sheet 1 is discharged to the finisher 600 by the fourth roller 404 (S7), and is stacked as a product on the tray of the finisher 600.

  In the case of a color measurement job (S3: Y), the switching flap 421 is positioned at a position for guiding the sheet to the detection path 431 (S10). That is, as shown in FIG. 13A, the switching flap 421 is held at the upper position. In the case of a colorimetric job, the power supply to the paper dust removing fan 801 is cut off, and the blowing to the detection path 431 stops (S10).

  After the image forming apparatus 100 forms an image of a colorimetric image pattern on a sheet based on a command from the profile creation unit 301 (S11), the adjustment unit 400 receives the sheet (S12). The sheet 1 first carried into the through path 430 is guided to the detection path 431 by the switching flap 421 (S13, FIG. 13A). When the sheet 1 reaches the horizontal portion 431b of the detection path 431 and passes the reading position of the color sensor 500, a colorimetric operation is performed by the color sensor 500, and the spectral reflectance of each patch image in the image pattern is measured. (S14, FIG. 13 (b)). Before the image pattern on the sheet reaches the reading position of the color sensor 500, the control unit 451 of the adjustment unit 400 reduces the transport speed of the sheet 1 to a transport speed V1 suitable for the measurement of the color sensor 500. The transport speed V1 is lower than the transport speed V0 (see FIGS. 12A and 12B) when the sheet 1 is transported through the through path 430 without passing through the detection path 431.

  The color measurement result of the color sensor 500 is transmitted to the image forming apparatus 100 via the communication unit 450, and is notified to the Lab operation unit 303 (S15). The Lab operation unit 303 converts the spectral reflectance of each patch image into coordinates in the L * a * b * color space according to the method described above, and calculates the ΔE value. The profile creation unit 301 creates an output ICC profile based on the calculation result of the Lab calculation unit 303 and the CMYK signal used for outputting the image pattern, and updates the output ICC profile stored in the memory 304 (S16).

  The sheet 1 that has passed the reading position of the color sensor 500 reaches the junction with the through path 430 via the ascending section 431c of the detection path 431, and is carried into the through path 430 (S17). Thereafter, the sheet 1 is transferred to the finisher 600 via the third roller 403 and the fourth roller 404 of the through path 430 (S7).

  In the case of the front and back register job (S3: N), the processing related to sheet conveyance is common to the case of the color measurement job. That is, when the front / back register job is executed, the switching flap 421 is positioned at a position for guiding the sheet to the detection path 431 (S20). Also, in the case of the front and back register job, the power supply to the paper dust removing fan 801 is cut off and the blowing to the detection path 431 is stopped (S20).

  After the image forming apparatus 100 forms an image of a front and back register image pattern on a sheet based on a command from the profile creation unit 301 (S21), the adjustment unit 400 receives the sheet (S22). The sheet 1 first carried into the through path 430 is guided to the detection path 431 by the switching flap 421 (S23, FIG. 14A). When the sheet 1 reaches the ascending section 431c of the detection path 431 and passes through the reading positions of the CIS 701 and 702 of the front and back register 700, the CIS 701 and 702 reads the sheet 1 and the test pattern on the sheet (S24, FIG. b), (c)). Before the image pattern on the sheet reaches the reading position of the back surface CIS 702, the control unit 451 of the adjustment unit 400 reduces the conveying speed of the sheet 1 to the conveying speed V2 suitable for reading the CIS 701 and 702. The transport speed V2 is lower than any of the transport speeds V0 and V1.

  The image data read by the CISs 701 and 702 is processed by the image processing unit 460, and a geometric adjustment amount is calculated (S25). The calculated geometric adjustment amount is transmitted to the image forming apparatus 100 via the communication unit 450 and registered in the sheet library 900 (S26).

  The sheet 1 that has passed the reading positions of the CISs 701 and 702 of the front and back register 700 reaches the junction with the through path 430 via the ascending section 431c of the detection path 431, and is carried into the through path 430 (S27). Thereafter, the sheet 1 is delivered to the finisher 600 via the third roller 403 and the fourth roller 404 of the through path 430 (S7, FIG. 14D).

  The above processing is repeatedly performed for each sheet of the number of sheets specified in the job, and after the processing for the last sheet is completed (S8: Y), the job ends (S9). In the control example shown in FIG. 11, the type of the job is determined for each sheet during the processing of the same job. However, the type is determined at the start of the job. The same processing as that for the sheet may be applied.

(Paper dust removal section)
Next, the paper dust removing unit 800 of the adjustment unit 400 will be described. As shown in FIG. 2, the paper dust removing unit 800 generates an air curtain that crosses the detection path 431 between the communication part P2 where the detection path 431 communicates with the through path 430 and the measurement position P1 of the front and back register 700. Thus, the intrusion of the paper dust into the measurement position P1 is reduced. However, the measurement position P1 of the front and back register 700 in the present embodiment refers to the reading position of the front CIS 701 and the back CIS 702 which is closer to the communication portion P2 (that is, the reading position of the front CIS 701 in the present embodiment). The communication portion is a portion where the sheet conveyance space in the two conveyance paths is connected, and the branch portion (the communication portion P3 of the present embodiment), the junction where the paths merge (the communication portion P2), and the path intersect. Including intersections. In addition, foreign substances that may enter the detection path 431 include substances other than paper dust (for example, worn pieces (rubber scum) of the transport roller and toner powder peeled off from the sheet). As an example, “paper powder” will be described.

  The paper dust removing unit 800 is disposed above the front and back register 700 and below the through path 430 in the vertical direction. In the present embodiment, the paper dust removing unit 800 is disposed in a space formed by the ascending portion 431c of the detection path 431 that is inclined with respect to the vertical direction. In other words, at least a part of the ascending portion 431c is arranged upward from the side surface 400s on the downstream device side (the left side in FIG. 2) of the adjustment unit 400 in order to secure the length of the straight section in which the front and back register portions 700 can be arranged. It is inclined with respect to the vertical direction so as to be separated. The paper dust removing section 800 is arranged in a space surrounded by the ascending section 431c, the side surface 400s, and the through path 430.

  As shown in FIGS. 15 and 16, the paper dust removing unit 800 includes a paper dust removing fan (hereinafter simply referred to as “fan”) 801 and a paper dust removing duct (hereinafter simply referred to as “duct”) 802. You. The fan 801 is a blower of the present embodiment, and the duct 802 is an airflow guide of the present embodiment.

  The fan 801 takes in air from outside the paper dust removing unit 800 and blows the air toward the duct 802. The fan 801 uses two sirocco fans, and is arranged so that the opening direction of the intake section is opposite between the upper side and the lower side. Further, the two fans 801 and 802 are arranged symmetrically with respect to the center position in the width direction of the detection path 431. The duct 802 disperses the airflow generated by the fan 801 in the width direction of the sheet by the guide plate 802a (FIG. 16) and discharges the airflow from the slit 802b (FIG. 15) extending in the width direction. The internal shape of the duct 802 (for example, the opening area of the air path entrance from the fan 801 to the duct 802), the amount of air blown by the fan 801 and the opening area of the slit 802b are 6 m / s over the entire detection path 431 in the width direction. It is adjusted so that the wind speed becomes s or more.

  As shown in FIG. 17, in the vicinity of the paper dust removing unit 800, a gap 805 is provided in the detection path 431 between the upstream transport guides 803a and 803b and the downstream transport guides 804a and 804b. The gap 805 has a first opening 805a provided on one guide surface of the sheet passing through the detection path 431, and a second opening 805a provided on the other guide surface facing the first opening 805a. 2 opening 805b. In other words, the first opening 805a is an opening formed in the first guide (803a, 804a) for guiding one surface of the sheet, and the second opening 805b is formed in the first guide with the sheet interposed. An opening provided in the opposing second guide (803b, 804b). The airflow generated by the paper dust removing unit 800 flows into the inside of the detection path 431 from the first opening 805a, and exits outside the detection path 431 from the second opening 805b.

  The first opening 805a and the second opening 805b are formed substantially over the entire length of the detection path 431 in the width direction so that an airflow flows in the entire area of the detection path 431 in the width direction. For example, the gap 805 is ensured by arranging the upstream transport guides 803a and 803b and the downstream transport guides 804a and 804b so as to be separated from each other in the sheet transport direction. The upstream portion of the downstream transport guides 804a and 804b has a shape in which the distance between the guide surfaces increases toward the upstream in the sheet transport direction so that the leading end of the sheet is not caught.

  As shown in the flowchart of FIG. 11, the fan 501 of the paper dust removing unit 800 performs the blowing operation during the execution of the normal job (S4), and stops during the execution of the color measurement job and the front / back registration job (S10, S20). ) Is controlled as follows. Further, in the case of the present embodiment, control is performed such that the blowing operation is performed even during the standby of the job. The reason why the fan 501 is operated during the execution of the normal job and the standby state of the job is that the paper dust generated from the sheet passing through the through path 430 (mainly, the paper dust derived from the sheet of the normal job) enters the detection path 431. This is to prevent it. In addition, the reason why the fan 501 is stopped during the execution of the colorimetric job and the front / back register job is that the airflow obstructed by the sheet flows into the detection path 431 to disturb the posture of the sheet, and the color sensor 500 and the CIS This is to prevent the measurement accuracy from lowering.

  As described above, in the present embodiment, in the configuration in which the detection path 431 is branched from the through path 430, air is blown between the measurement position P1 of the front and back register 700 and the communication portion P2 of the detection path 431 and the through path 430. A paper dust removing unit 800 is provided. In other words, air is blown toward the second transport path between the communication section (P2) where the second transport path communicates with the first transport path and the measurement position (P1) where the measurement unit measures the image pattern of the sheet. A ventilation means is provided. This can reduce the possibility that the paper dust generated in the through path 430 enters the measurement position P1 of the front and back register 700 in the detection path 431 and causes a reading failure of the front and back register 700. As a result, it is possible to set a longer interval for performing maintenance such as checking and cleaning of the front and back register 700, thereby reducing downtime of the apparatus and contributing to an improvement in the operation rate of the image forming system 100S.

  In the case of the present embodiment, the sheet passing the detection path 431 is a sheet on which an image pattern for measurement is formed, and the sheet of the normal job representing most of the entire sheet passing the adjustment unit 400 has only the through path 430. And transported to downstream equipment. Therefore, the amount of paper dust generated in the detection path 431 is much smaller than that generated in the through path 430 (for example, less than one tenth). Therefore, by arranging the paper dust removing unit 800 at the above-described position where the paper dust is prevented from entering through the through path 430, it is possible to effectively reduce the influence of the paper dust on the front and back register 700.

  Further, in the present embodiment, in the configuration in which the detection path 431 bypasses below the through path 430, the paper dust removing unit 800 is configured to blow air toward the position between the measurement position P1 and the communication unit P2 in the vertical direction. . By arranging the front and back register 700 below the through path 430, it is possible to reduce the temperature rise of the CIS 701 and 702 due to the heat radiated from the sheet of the normal job, and to reduce the decrease in the reading accuracy due to the thermochromism phenomenon and the thermal noise. . Further, since the paper dust removing unit 800 blows air toward the position between the measurement position P1 and the communication unit P2 in the vertical direction, it is possible to prevent the paper dust generated in the through path 430 from dropping into the detection path 431 due to gravity. Is possible. That is, with the configuration of the present embodiment, it is possible to minimize the influence of the intrusion of paper dust on the measurement result while reducing the influence of heat on the measuring means.

  Further, the front and back register 700 of the present embodiment employs an image sensor of the same magnification optical system (the front surface CIS 701 and the back surface CIS 702). In general, an image sensor of the same magnification optical system generally has a shallower depth of focus compared to an image sensor of a reduction optical system, and forms a linear image when paper dust adheres to the transparent guides 703 and 704 (see FIG. 7). It is known that a defect (streak image) easily occurs. It is conceivable to dispose a fan that blows off the paper dust attached to the transparent guides 703 and 704. However, if the paper dust is strongly adsorbed by static electricity or the like, the removal of the paper dust may be insufficient. On the other hand, since the paper dust removing unit 800 of the present embodiment reduces the penetration of the paper dust into the measurement position P1 of the front and back register 700, the paper dust removal unit 800 reduces the adhesion of the paper dust to the transparent guides 703 and 704. It can be reduced. In other words, by arranging the paper dust removing unit 800, it is possible to reduce the possibility of occurrence of a CIS reading failure while taking advantage of the CIS that is compact and capable of reading while conveying a sheet.

(Modification)
In the above-described embodiment, the paper dust removing unit 800 is disposed on the downstream device side (left side in FIG. 2) with respect to the detection path 431. However, as shown in FIG. It may be arranged on the upstream device side (right side in the figure). In this case, although the flow direction of the air flow is opposite, as shown in FIG. 19, the air flow generated by the paper dust removing unit 800 is arranged so as to form an air curtain that crosses the detection path 431, so that the front and back register unit 700 can be reduced.

  Further, in the present embodiment, the paper dust removing unit 800 is provided between the communication part P2 on the exit side of the detection path 431 and the measurement position P1 of the front and back register 700 among the two communication parts of the detection path 431 and the through path 430. Have a configuration that forms an air curtain. However, for example, the paper dust removing unit that forms the air curtain between the communication part P3 on the entrance side of the detection path 431 (see FIG. 2) and the measurement position P4 of the color sensor 500 is replaced with the paper dust removing unit 800 of the present embodiment. Or in place of the paper dust removing unit 800. The present technology is also applicable, for example, when the detection path 431 communicates with the through path 430 at one end and has a dead end shape (a configuration in which the sheet to be measured is switched back) at the other end. . In this case, the paper dust removing unit 800 may be arranged so as to form an air curtain between the communicating portion between the detection path 431 and the through path 430 and the measurement position of the measuring unit arranged on the detection path 431.

  The above-mentioned fan 501 is an example of a blowing means, and a centrifugal fan other than an axial fan or a sirocco fan may be used, and the number and arrangement can be changed as appropriate. Further, the air curtain is not limited to the air blower installed mainly for removing paper dust, and a part of the air current generated by the air blower for cooling the inside of the adjustment unit 400 is guided to the detection path 431 to form an air curtain. May be configured.

  Further, in the present embodiment, the internal space of the through path 430 and the measurement position P1 of the front and back register 700 in the detection path 431 are blocked by the air curtain. However, it is possible to reduce the intrusion of paper dust to the measurement position P1. For example, a configuration without using an air curtain may be adopted. For example, the airflow generated by the paper dust removing unit 800 flows into the detection path 431 at a position between the measurement position P1 and the communication part P2, and flows toward the communication part P2 so that the paper dust is pushed back to the through path 430. It may be. In this case, an opening is provided in any part of the through path 430 so that the airflow generated by the paper dust removing unit 800 is released.

(Other embodiments)
In the above-described embodiment, the electrophotographic image forming engine 102 is used as an image forming unit. The present technology is also applicable.

  The present invention supplies a program for realizing one or more functions of the above-described embodiments to a system or an apparatus via a network or a storage medium, and one or more processors in a computer of the system or the apparatus read and execute the program. This processing can be realized. Further, it can also be realized by a circuit (for example, an ASIC) that realizes one or more functions.

100 image forming apparatus / 100S image forming system / 102 image forming means (image forming engine) / 400 measuring device (adjusting unit) / 400s side surface of measuring device (side surface of adjusting unit) / 430 first conveyance Path (through path) / 431: Second transport path (detection path) / 431c ... Ascending part / 500, 700 ... Measurement means (color sensor, front / back register) / 600 ... Sheet processing device (finisher) / 801 ... Blowing means ( Paper dust removal fan) / 802 Airflow guide (paper dust removal duct) / 803a, 804a First guide (conveyance guide) / 803b, 804b Second guide (conveyance guide) / 805a, 805b Opening / P1 Measurement position / P2 ... Communication part

Claims (9)

A measurement device connected to an image forming apparatus that forms an image on a sheet,
A first transport path for transporting the sheet discharged from the image forming apparatus toward a sheet processing apparatus connected to the measuring apparatus;
A second transport path branched from the first transport path,
A measuring unit disposed on the second transport path, for measuring an image pattern of a sheet discharged from the image forming apparatus;
A communication unit that connects the second conveyance path to the first conveyance path; and a blowing unit that blows the second conveyance path between a measurement position where the measurement unit measures an image pattern of a sheet. ,
A measuring device characterized by the above-mentioned. The measuring means is provided below the first transport path,
The blowing means blows air in a direction above the measurement position in the vertical direction in the second transport path, and toward a portion below the communication portion.
The measuring device according to claim 1, wherein: The second conveyance path extends downward from the first conveyance path, and extends downward in the sheet conveyance direction of the second conveyance path. Having an ascending section that joins the transport path,
The measuring means is arranged in the ascending part,
The measuring device according to claim 2, wherein: The second transport path has a first guide and a second guide opposed to the sheet passing through the second transport path with a sheet interposed therebetween, and an airflow generated by the air blowing unit generates the airflow generated by the first guide and the second guide. Configured to traverse the second transport path through an opening provided in the guide,
The measuring device according to claim 1, wherein: An airflow guide that distributes the airflow generated by the blowing unit in a width direction orthogonal to a sheet conveyance direction in the second conveyance path and guides the airflow to the second conveyance path;
The measuring device according to any one of claims 1 to 4, wherein: A control unit that controls an operation of the blowing unit, wherein when the sheet discharged from the image forming apparatus is transported to the sheet processing apparatus without passing through the second transport path, the blowing unit performs a blowing operation on the blowing unit. When the measurement unit is configured to convey the sheet discharged from the image forming apparatus to the second conveyance path and perform measurement by the measurement unit, the control unit stops the blowing operation of the blowing unit.
The measuring device according to any one of claims 1 to 5, wherein: The measurement unit includes a light source that irradiates light to a sheet passing through the measurement position, a plurality of image sensors arranged in a width direction orthogonal to a sheet conveyance direction in the second conveyance path, and arranged in the width direction. And a plurality of lenses for guiding the reflected light from the sheet to the plurality of imaging elements, and a contact image sensor having
The measuring device according to any one of claims 1 to 6, wherein: An image forming apparatus that forms an image on a sheet according to image forming conditions;
The measurement device according to claim 1, which is connected to the image forming device,
And a sheet processing device connected to the measuring device,
An image forming system in which an image forming condition of the image forming apparatus is changed according to a measurement result of the measuring device. An image forming apparatus including an image forming unit that forms an image on a sheet,
A first transport path for transporting a sheet on which an image is formed by the image forming unit toward a discharge unit that discharges a sheet from the image forming apparatus;
A second transport path branched from the first transport path,
A measuring unit that is arranged in the second transport path and measures an image pattern formed on a sheet by the image forming unit;
A communication unit that connects the second transport path to the first transport path; and a blower that blows the second transport path between a measurement position where the measurement unit measures an image pattern of a sheet. ,
An image forming apparatus comprising:

Images