JP2017175603A - Imaging system, image formation device, imaging method and program - Google Patents

Abstract

An object of an imaging target is imaged with high accuracy. An imaging unit that moves relative to an imaging target and images the imaging target, a detection unit that detects a predetermined relative position between the imaging unit and the imaging target, Control means 52 for switching from stop to supply of a system clock for controlling the timing of image pickup start by the image pickup means 15 in response to detection of the predetermined relative position by the detection means 80, and the control means 52 After stopping the supply of the system clock, the supply of the system clock to the imaging unit 15 is resumed in accordance with the relative movement of the imaging object based on the detection of the predetermined relative position by the detection unit 80. [Selection] Figure 8

Description

  The present invention relates to an imaging system, an image forming apparatus, an imaging method, and a program.

  Conventionally, an image forming apparatus picks up an image of a color pattern (imaging target) formed on a recording medium by an image pickup apparatus, and forms an image based on a color pattern RGB value or a colorimetric value converted from the RGB value obtained by the image pickup. A technique for adjusting the color of the apparatus is known (for example, see Patent Document 1).

  The above-described technique has an advantage that self-calibration processing can be performed with low cost and high accuracy with respect to variations due to temporal variations in the spectral distribution of the LED light source and the spectral sensitivity of the sensor.

  By the way, in an imaging apparatus using a low-cost CMOS (Complementary MOS) two-dimensional sensor or the like, the frame rate is fixed and the frame rate is lowered. When performing colorimetry or measurement of an imaging target using such an imaging apparatus, there has been a problem that the timing of imaging with respect to the imaging target does not match and an image of the imaging target cannot be acquired.

  The present invention has been made in view of the above, and an object of the present invention is to provide an imaging system, an image forming apparatus, an imaging method, and a program capable of imaging a target location in an imaging object with high accuracy. .

  In order to solve the above-described problems and achieve the object, the present invention relates to an imaging unit that moves relative to an imaging target and images the imaging target, the imaging unit, and the imaging target. Detection means for detecting a predetermined relative position; and control means for switching from stop to supply of a system clock for controlling the timing of imaging start by the imaging means in response to detection of the predetermined relative position by the detection means; The control means, after stopping the supply of the system clock, based on the detection of the predetermined relative position by the detection means, the system clock to the imaging means in accordance with the relative movement of the imaging object Restart supply.

  According to the present invention, there is an effect that a target location in an imaging object can be imaged with high accuracy.

FIG. 1 is an external view of an image forming apparatus according to an embodiment. FIG. 2 is a perspective view showing an appearance of the imaging system. FIG. 3 is an exploded perspective view of the imaging system. FIG. 4 is a longitudinal sectional view of the imaging system viewed from the X1 direction in FIG. FIG. 5 is a longitudinal sectional view of the imaging system viewed from the X2 direction in FIG. FIG. 6 is a plan view of the imaging system. FIG. 7 is a diagram illustrating a specific example of the reference chart. FIG. 8 is a block diagram illustrating a functional configuration example of the imaging system. FIG. 9 is a diagram for explaining the relationship between the system clock (SCLK) and the horizontal synchronization signal (HSYNC). FIG. 10 is a diagram for explaining the relationship between the horizontal synchronization signal (HSYNC) and the vertical synchronization signal (VSYNC). FIG. 11 is a diagram for explaining the relationship between the vertical synchronization signal (VSYNC) and the imaging (frame) cycle. FIG. 12 is a timing chart showing the relationship between signals when a timing signal is supplied from the moving body detection sensor within an imaging (frame) cycle of one screen. FIG. 13 is a schematic diagram illustrating a positional relationship between the moving object detection sensor and the moving object. FIG. 14 is a timing chart showing a modified example of the relationship between signals when a timing signal is supplied from a moving body detection sensor within an imaging (frame) cycle of one screen. FIG. 15 is a timing chart showing another modified example of the relationship between signals when a timing signal is supplied from a moving body detection sensor within an imaging (frame) cycle of one screen. FIG. 16 is a block diagram illustrating a hardware configuration example of the image forming apparatus.

  Hereinafter, embodiments of an imaging system, an image forming apparatus, an imaging method, and a program will be described in detail with reference to the accompanying drawings. In the embodiment described below, an electrophotographic image forming apparatus configured as a production printing machine is illustrated as an example of an image forming apparatus to which the present invention is applied. The present invention can be widely applied to various types of image forming apparatuses to be formed, and can naturally be applied to an ink jet method.

<Image forming apparatus>
FIG. 1 is an external view of an image forming apparatus 100 according to the embodiment. As shown in FIG. 1, the image forming apparatus 100 according to the present embodiment includes a main body unit 101 that performs electrophotographic image formation on a recording medium M (see FIG. 5). That is, the main unit 101 functions as an image forming unit.

  Then, a large-capacity paper feeding unit 102 that supplies the recording medium M to the main body unit 101, an inserter 103 that is used to supply a cover or the like, and a recording medium M on which an image is formed are folded. Peripheral machines such as a folding unit 104 to perform, a finisher 105 to perform stapling and punching, and a cutting machine 106 to perform cutting are combined in accordance with the application.

  The image forming apparatus 100 is connected to an external controller 200 called DFE (Digital Front End).

  The main unit 101 is supplied from a paper feed tray or a large-capacity paper supply unit 102 inside the main unit 101 by an electrophotographic image forming process based on raster image data subjected to RIP (Raster Image Processing) processing by the external controller 200. An image is formed on the recording medium M.

  The recording medium M on which an image is formed by the main unit 101 is conveyed to the subsequent stage of the main unit 101. The recording medium M is bound by, for example, a cover sheet supplied from the inserter 103 and the like by folding processing by the folding unit 104, stapling and punching by the finisher 105, and cutting by the cutting machine 106 as necessary. Since the electrophotographic image forming process executed by the main unit 101 and the processing in each peripheral device connected to the main unit 101 are both known, detailed description thereof will be omitted.

  The color of an image formed on the recording medium M by the main unit 101 may not necessarily have a desired color due to characteristics inherent to the main unit 101 and changes in characteristics over time. Therefore, the image forming apparatus 100 according to the present embodiment performs calibration such as color adjustment at a predetermined timing in order to improve the color reproducibility of image formation by the main unit 101.

  At the time of calibration, the image forming apparatus 100 forms a color pattern (an example of an imaging object) of a predetermined color on the recording medium M by the main body unit 101, and the color pattern is formed by an imaging system 10 (see FIG. 2) described later. read. Then, the image forming apparatus 100 is based on the RGB value of the obtained color pattern or a colorimetric value of the color pattern calculated based on the RGB value (RGB value and colorimetric value are examples of color information). By adjusting various parameters of the image forming process, the color of the image formed by the main unit 101 is brought close to the target color.

  The imaging system 10 that reads the color pattern formed on the recording medium M by the main unit 101 includes a two-dimensional sensor 15a (see FIG. 4) disposed in the conveyance path of the recording medium M on which the color pattern is formed. In the present embodiment, the two-dimensional sensor 15a is configured as a main body of an imaging device 15 (see FIG. 3) which is an imaging unit described later. As will be described in detail later, the imaging device 15 is configured to capture an image including a color pattern with the imaging device 15 and calculate a colorimetric value of the color pattern based on the captured image.

  The colorimetric values of the color pattern calculated by the two-dimensional sensor 15a constituting the imaging device 15 are sent to the main unit 101.

  Then, the main unit 101 adjusts various parameters in the image forming process based on the color measurement values of the color pattern sent from the two-dimensional sensor 15a. As a result, color adjustment for adjusting the amount of toner used as a color material on the recording medium M is performed, and the color of the image formed by the main unit 101 is brought close to the target color.

  Note that the main unit 101 in the image forming apparatus 100 of the present embodiment is configured to adjust various parameters in the image forming process based on the colorimetric values of the color pattern, but is not limited to this. For example, the main unit 101 may be configured to adjust various parameters in the image forming process based on the RGB values of the color pattern. In this case, the two-dimensional sensor 15a configuring the imaging device 15 may be configured to capture an image including a color pattern and output an RGB value, and may not have a function of calculating a colorimetric value of the color pattern. Good.

  In the present embodiment, the two-dimensional sensor 15a is used as the imaging device 15 that reads a color pattern. However, the present invention is not limited to this. For example, the imaging device 15 may be configured to acquire at least color information of a color pattern. Therefore, instead of the two-dimensional sensor 15a, a detector having a simple configuration including a light receiving element that receives reflected light is used, and such a detector is arranged in the conveyance path of the recording medium M on which the color pattern is formed. The imaging device 15 may be configured.

  In the present embodiment, a configuration in which the imaging system 10 that reads a color pattern is incorporated in the image forming apparatus 100, that is, a configuration in which the image forming apparatus 100 includes the imaging system 10 is illustrated, but the present invention is not limited thereto. For example, as an apparatus different from the image forming apparatus 100, an imaging system that reads a color pattern formed on the recording medium M by the image forming apparatus 100 may be configured. Also in this case, the imaging system is configured by an imaging device or a detector arranged in the conveyance path of the recording medium M on which the color pattern is formed.

  In the present embodiment, the imaging device 15 is stopped and the imaging object (color pattern formed on the recording medium M) moves in the transport direction. However, the present invention is not limited to this. The imaging target object (color pattern formed on the recording medium M) may be stopped and the imaging device 15 may move in the main scanning direction. In other words, any object may be used as long as the imaging device 15 moves relative to the imaging object (color pattern formed on the recording medium M) and images the imaging object.

  In addition, in the present embodiment, the main unit 101 is a moving body that is a detection unit at a predetermined position on the conveyance path of the recording medium M (see FIG. 5) and upstream of the imaging system 10 in the conveyance direction. A detection sensor 80 (see FIG. 8) is provided.

  The moving body detection sensor 80 is a photosensor that optically detects the tip of the recording medium M (moving body) that passes a predetermined position on the transport path toward the imaging system 10.

  Specifically, when the leading end of the conveyed recording medium M is detected, the moving body detection sensor 80 outputs the information (timing signal) to the imaging system 10.

<Imaging system>
Next, a specific example of the imaging system 10 of the present embodiment will be described. 2 is a perspective view showing an appearance of the imaging system 10, FIG. 3 is an exploded perspective view of the imaging system 10, FIG. 4 is a longitudinal sectional view of the imaging system 10 viewed from the X1 direction in FIG. 2, and FIG. FIG. 6 is a plan view of the imaging system 10 as viewed from the X2 direction.

  The imaging system 10 includes a housing 11 formed in, for example, a rectangular box shape. The housing 11 includes, for example, a bottom plate portion 11a and a top plate portion 11b that are opposed to each other with a predetermined interval, and side wall portions 11c, 11d, 11e, and 11f that connect the bottom plate portion 11a and the top plate portion 11b. The bottom plate portion 11a and the side wall portions 11d, 11e, and 11f of the housing 11 are integrally formed by, for example, molding, and the top plate portion 11b and the side wall portion 11c are configured to be detachable. In FIG. 3, the state which removed the top-plate part 11b and the side wall part 11c is shown.

  For example, the imaging system 10 is installed in the conveyance path of the recording medium M on which the color pattern is formed in a state where a part of the housing 11 is supported by a predetermined support member. At this time, as shown in FIGS. 4 and 5, the imaging system 10 is configured so that the bottom plate portion 11 a of the housing 11 faces the recording medium M being conveyed in a substantially parallel state with a gap d therebetween. It is supported by a predetermined support member.

  An opening 13 is provided in the bottom plate portion 11a of the housing 11 facing the recording medium M on which the color pattern is formed, so that a color pattern outside the housing 11 can be imaged from the inside of the housing 11. Yes.

  Further, a reference chart 30 is arranged on the inner surface side of the bottom plate portion 11 a of the housing 11 so as to be adjacent to the opening portion 13 through the support member 23. The reference chart 30 is imaged together with the color pattern by the imaging device 15 described later when performing colorimetry of the color pattern and acquisition of RGB values. Details of the reference chart 30 will be described later.

  On the other hand, a circuit board 14 is disposed on the top plate portion 11 b side inside the housing 11. As shown in FIG. 6, a square box-shaped casing 11 whose surface on the circuit board 14 side is open is fixed to the circuit board 14 by a fastening member 14 b. The casing 11 is not limited to a square box shape, and may be, for example, a cylindrical box shape having a bottom plate portion 11a in which an opening 13 is formed, an elliptic cylinder box shape, or the like.

  An imaging device 15 that captures an image is disposed between the top plate portion 11 b of the housing 11 and the circuit board 14. As illustrated in FIG. 4, the imaging device 15 includes a two-dimensional sensor 15 a such as a two-dimensional sensor 15 a such as a CCD (Charge Coupled Device) sensor or a CMOS (Complementary Metal Oxide Semiconductor) sensor, and an imaging range of the imaging device 15. And a lens 15b that forms an image on the light receiving surface (imaging region). The two-dimensional sensor 15a is a light-receiving element array in which light-receiving elements that receive reflected light from a subject are arranged two-dimensionally.

  For example, the imaging device 15 is held by a sensor holder 16 formed integrally with the side wall portion 11e of the housing 11. The sensor holder 16 is provided with a ring portion 16 a at a position facing the through hole 14 a formed in the circuit board 14. The ring portion 16a has a through hole having a size that follows the outer shape of the protruding portion of the imaging device 15 on the lens 15b side. The imaging device 15 inserts the protruding portion on the lens 15 b side into the ring portion 16 a of the sensor holder 16 so that the lens 15 b faces the bottom plate portion 11 a side of the housing 11 through the through hole 14 a of the circuit board 14. And held by the sensor holder 16.

  At this time, in the imaging device 15, the optical axis indicated by the one-dot chain line in FIG. 4 is substantially perpendicular to the bottom plate portion 11a of the housing 11, and the opening 13 and a reference chart 30 described later are included in the imaging range. As described above, the sensor holder 16 is held in a positioned state. Thereby, the imaging device 15 images a color pattern outside the housing 11 through the opening 13 in a part of the imaging region of the two-dimensional sensor 15a. In addition, the imaging device 15 can image the reference chart 30 arranged inside the housing 11 in another part of the imaging region of the two-dimensional sensor 15a.

  The imaging device 15 is electrically connected to the circuit board 14 on which various electronic components are mounted via, for example, a flexible cable. The circuit board 14 is provided with an external connection connector 17 to which a connection cable for connecting the imaging system 10 to the main control board of the image forming apparatus 100 is attached.

  In the imaging system 10, the circuit board 14 is positioned on the center line Lo in the sub-scanning direction passing through the center of the imaging device 15 and at a predetermined distance from the center of the imaging device 15 in the sub-scanning direction. A pair of light sources 18 are provided. The light source 18 illuminates the imaging range substantially uniformly during imaging by the imaging device 15. As the light source 18, for example, an LED (Light Emitting Diode) advantageous for space saving / power saving is used.

  In the present embodiment, as shown in FIGS. 5 and 6, a pair of LEDs that are evenly arranged in a direction orthogonal to the direction in which the opening 13 and the reference chart 30 are arranged with respect to the center of the lens 15 b as a light source 18. It is used as.

  The two LEDs used as the light source 18 are mounted on the surface of the circuit board 14 on the bottom plate part 11a side, for example. However, the light source 18 only needs to be disposed at a position where the imaging range of the imaging device 15 can be illuminated substantially uniformly by the diffused light, and is not necessarily mounted directly on the circuit board 14. Further, the positions of the two LEDs are arranged at symmetrical positions with the two-dimensional sensor 15a as the center, thereby enabling the imaging surface to be imaged under the same illumination conditions as the reference chart 30 side. Moreover, in this embodiment, although LED was used as the light source 18, the kind of light source 18 is not limited to LED. For example, an organic EL or the like may be used as the light source 18. When the organic EL is used as the light source 18, illumination light close to the spectral distribution of sunlight can be obtained, so that improvement in colorimetric accuracy can be expected.

  As shown in FIG. 6, the imaging device 15 includes a light absorber 15c immediately below the light source 18 and the two-dimensional sensor 15a. The light absorber 15c reflects or absorbs light from the light source 18 in a direction other than the two-dimensional sensor 15a. The light absorber 15c has an acute shape and is formed such that incident light from the light source 18 is reflected to the inner surface of the light absorber 15c, and does not reflect in the incident direction.

  An optical path length changing member 19 is disposed inside the housing 11 in the optical path between the imaging device 15 and a color pattern outside the housing 11 that is imaged by the imaging device 15 through the opening 13. Has been. The optical path length changing member 19 is an optical element having a refractive index n and having a sufficient transmittance for the light from the light source 18. The optical path length changing member 19 has a function of bringing the imaging surface of the optical image of the color pattern outside the housing 11 closer to the imaging surface of the optical image of the reference chart 30 inside the housing 11. That is, in the imaging system 10, the optical path length is changed by arranging the optical path length changing member 19 in the optical path between the imaging device 15 and the subject outside the housing 11. Thereby, the imaging system 10 receives both the imaging surface of the optical image of the color pattern outside the housing 11 and the imaging surface of the reference chart 30 inside the housing 11 by the two-dimensional sensor 15a of the imaging device 15. I try to match the surface. Therefore, the imaging device 15 can capture an image focused on both the color pattern outside the housing 11 and the reference chart 30 inside the housing 11.

  As shown in FIG. 4, for example, the optical path length changing member 19 is supported by a pair of ribs 20 and 21 at both ends of the surface on the bottom plate portion 11a side. In addition, since the pressing member 22 is disposed between the surface of the optical path length changing member 19 on the top plate portion 11 b side and the circuit board 14, the optical path length changing member 19 is prevented from moving inside the housing 11. Yes. The optical path length changing member 19 is disposed so as to close the opening 13 provided in the bottom plate portion 11 a of the housing 11. Therefore, in the optical path length changing member 19, impurities such as ink mist and dust that enter the housing 11 from the outside of the housing 11 through the opening 13 adhere to the imaging device 15, the light source 18, the reference chart 30, and the like. It also has a function to prevent this.

  The mechanical configuration of the imaging system 10 described above is merely an example, and the present invention is not limited to this. In the imaging system 10, at least while the light source 18 provided inside the casing 11 is lit, the imaging device 15 provided inside the casing 11 applies the color pattern outside the casing 11 to the opening 13. Any configuration may be used as long as the image is captured through the network. The imaging system 10 can be variously modified and changed with respect to the above configuration.

  For example, in the imaging system 10 described above, the reference chart 30 is arranged on the inner surface side of the bottom plate portion 11 a of the housing 11. However, an opening other than the opening 13 is provided at a position where the reference chart 30 of the bottom plate portion 11a of the housing 11 is disposed, and the reference chart 30 is provided from the outside of the housing 11 at a position where the opening is provided. The structure which attaches may be sufficient. In this case, the imaging device 15 captures an image of the color pattern formed on the recording medium M through the opening 13, and is applied to the bottom plate portion 11 a of the housing 11 through an opening different from the opening 13. The reference chart 30 attached from the outside is imaged. In this example, there is an advantage that replacement can be easily performed when a defect such as a stain occurs in the reference chart 30.

  Next, a specific example of the reference chart 30 arranged in the housing 11 of the imaging system 10 will be described with reference to FIG. FIG. 7 is a diagram illustrating a specific example of the reference chart 30.

  The reference chart 30 shown in FIG. 7 includes a plurality of colorimetric patch rows 31 to 34 in which colorimetric patches for colorimetry are arranged, a distance measurement line 35, and a chart position specifying marker 36.

  The color measurement patch sequences 31 to 34 are a color measurement patch sequence 31 in which YMCK primary color measurement patches are arranged in gradation order, and a color measurement patch sequence in which RGB secondary color measurement patches are arranged in gradation order. 32, a colorimetric patch array (achromatic color gradation pattern) 33 in which grayscale colorimetric patches are arranged in order of gradation, and a colorimetric patch array 34 in which tertiary colorimetric patches are arranged.

  The distance measurement line 35 is formed as a rectangular frame surrounding the plurality of colorimetric patch rows 31 to 34. The chart position specifying markers 36 are provided at the positions of the four corners of the distance measuring line 35 and function as markers for specifying the positions of the colorimetric patches. By specifying the distance measurement line 35 and the chart position specifying markers 36 at the four corners thereof from the image of the reference chart 30 captured by the imaging device 15, the position of the reference chart 30 and the position of each colorimetric patch are specified. be able to.

  Each colorimetric patch constituting the colorimetric patch rows 31 to 34 for colorimetry is used as a color reference reflecting the imaging conditions of the imaging device 15. The configuration of the colorimetric patch rows 31 to 34 for colorimetry arranged on the reference chart 30 is not limited to the example shown in FIG. 7, and any colorimetric patch row can be applied. It is. For example, a colorimetric patch that can specify a color range as wide as possible may be used, and the colorimetric patch row 31 of the primary color of YMCK and the colorimetric patch row 33 of the gray scale may be used as the image forming apparatus 100. It may be composed of patches of colorimetric values of the color material used in the above. The RGB secondary color measurement patch array 32 may be composed of patches of color measurement values that can be developed with a color material used in the image forming apparatus 100, and color measurement such as Japan Color. A reference color chart having a predetermined value may be used.

  In this embodiment, the reference chart 30 having the colorimetric patch rows 31 to 34 having a general patch (color chart) shape is used. However, the reference chart 30 is not necessarily limited to such a colorimetric patch row 31. It may not be the form which has -34. The reference chart 30 may have a configuration in which a plurality of colors that can be used for colorimetry are arranged so that their positions can be specified.

  Since the reference chart 30 is arranged on the inner surface side of the bottom plate portion 11a of the housing 11 so as to be adjacent to the opening portion 13 as described above, the imaging device 15 simultaneously captures the color pattern outside the housing 11. can do. Note that the simultaneous imaging here means that one frame of image data including the color pattern outside the housing 11 and the reference chart 30 is acquired. That is, even if there is a time difference in data acquisition for each pixel, if the image data including the color pattern outside the housing 11 and the reference chart 30 is acquired in one frame, the color pattern outside the housing 11 and the reference chart 30 is imaged at the same time. That is, the color pattern outside the housing 11 and the reference chart 30 need only be arranged at a position where images can be simultaneously captured, and an image obtained by simultaneously capturing the color pattern outside the housing 11 and the reference chart 30 is used. There is no need.

  Next, a functional configuration of the imaging system 10 will be described with reference to FIG. FIG. 8 is a block diagram illustrating a functional configuration example of the imaging system 10.

  As illustrated in FIG. 8, the imaging system 10 includes a control unit 50. The control unit 50 receives the system clock (SCLK), receives the vertical synchronization signal (VSYNC), the horizontal synchronization signal (HSYNC), and the image data from the imaging device 15, and processes the received image data.

  The control unit 50 includes a light source drive control unit 51, a clock signal generation unit 52, a frame memory 53, an averaging processing unit 54, a colorimetric calculation unit 55, and a nonvolatile memory 56. Each of these units is realized using, for example, a computer system including a processor and a memory, or dedicated hardware such as an FPGA or an ASIC. The hardware that realizes the functions of these units is mounted on, for example, a circuit board 14 disposed inside the casing 11 of the imaging system 10.

  The imaging device 15 converts light incident through the lens 15b into an electrical signal by the two-dimensional sensor 15a, and outputs image data in the imaging range illuminated by the light source 18. The imaging device 15 AD converts an analog signal obtained by photoelectric conversion of the two-dimensional sensor 15a into digital image data. The imaging device 15 outputs the image data after performing various image processing such as shading correction, white balance correction, γ correction, and image data format conversion. Various operation conditions of the two-dimensional sensor 15a are set according to various setting signals from the CPU 110 mounted on the main control board of the image forming apparatus 100, for example. Note that some or all of the various types of image processing on the image data may be performed outside the imaging device 15.

  The light source drive control unit 51 generates a light source drive signal for turning on the light source 18 and supplies the light source 18 to the light source 18 when an image is captured by the imaging device 15.

  The clock signal generation unit 52 generates a system clock (SCLK) signal that controls the timing of image capturing start by the image capturing device 15 and supplies the system clock (SCLK) signal to the image capturing device 15. The clock signal generation unit 52 functions as a control unit that switches from a stop to a supply of a system clock (SCLK) signal that controls the timing of imaging start by the imaging device 15.

  FIG. 9 is a diagram for explaining the relationship between the system clock (SCLK) and the horizontal synchronization signal (HSYNC). As illustrated in FIG. 9, the horizontal synchronization signal (HSYNC) is output from the imaging device 15 in accordance with the number of system clocks for horizontal pixels supplied from the clock signal generation unit 52.

  FIG. 10 is a diagram for explaining the relationship between the horizontal synchronization signal (HSYNC) and the vertical synchronization signal (VSYNC). As illustrated in FIG. 10, the vertical synchronization signal (VSYNC) is output from the imaging device 15 with the number of horizontal synchronization signal clocks equal to the number of vertical pixels.

  FIG. 11 is a diagram for explaining the relationship between the vertical synchronization signal (VSYNC) and the imaging (frame) cycle. As shown in FIG. 11, one cycle of the vertical synchronization signal (VSYNC) is an imaging (frame) cycle of one screen in the imaging device 15. As shown in FIG. 11, the frame period is composed of vertical synchronization signal = H (substantial image capturing engine) and vertical synchronization signal = L (idle period). In the idle period, internal calculation processing such as gamma conversion inside the sensor is performed on the frame data. In the present embodiment, the frame period is 33.3 [ms] = 30 [fps (frame per sec)].

  The frame memory 53 temporarily stores the image output from the imaging device 15.

  When the color measurement is performed on the color pattern, the averaging processing unit 54 uses an image area (delimited by the opening 13 of the housing 11) from the image output from the imaging device 15 and temporarily stored in the frame memory 53. Hereinafter, this image region is referred to as “subject image region”) and an image region in which the reference chart 30 is projected (hereinafter, this image region is referred to as “reference chart image region”). The averaging processing unit 54 averages the image data of a predetermined size area in the center of the subject image area, and outputs the obtained value as the RGB value of the color pattern. The averaging processing unit 54 averages the image data of each colorimetric patch area in the reference chart image area, and outputs the obtained value as the RGB value of each colorimetric patch. The RGB values of these color patterns and the RGB values of each colorimetric patch in the reference chart 30 are passed to the colorimetric calculation unit 55.

  A colorimetric calculation unit 55 that is a colorimetric calculation unit calculates a colorimetric value of a color pattern based on the RGB value of the color pattern acquired from the averaging processing unit 54 and the RGB value of each colorimetric patch of the reference chart 30. calculate. The color measurement value of the color pattern calculated by the color measurement calculation unit 55 is sent to the CPU 110 mounted on the main control board of the image forming apparatus 100. Note that the colorimetric calculation unit 55 can calculate the colorimetric values of the color pattern by, for example, the method disclosed in Patent Document 1, and therefore a detailed description of the processing of the colorimetric calculation unit 55 is omitted here. The RGB values of each colorimetric patch in the reference chart 30 are used for drive control such as error correction caused by fluctuations in the light source 18, etc., integration time in the two-dimensional sensor 15a such as a CMOS sensor, white balance adjustment, It may be used for gamma correction.

  The nonvolatile memory 56 stores various data necessary for the colorimetric calculation unit 55 to calculate a colorimetric value of the color pattern.

  The imaging system 10 configured as described above is disposed in the conveyance path of the recording medium M on which the color pattern is formed by the main body unit 101 of the image forming apparatus 100. For example, the imaging system 10 is arranged on the conveyance path of the recording medium M in the finisher 105 of the image forming apparatus 100. When the recording medium M on which the color pattern is formed is discharged from the main unit 101, the imaging system 10 turns on the light source 18. Then, the imaging system 10 performs imaging by the imaging device 15 at a timing when the color pattern on the recording medium M comes to a position facing the opening 13 provided in the housing 11 as the recording medium M is conveyed. Then, the colorimetric calculation unit 55 calculates the colorimetric value of the color pattern based on the image obtained by the imaging of the imaging device 15, and the CPU 110 mounted on the main control board of the image forming apparatus 100 with the calculated colorimetric value. Send to etc. Then, under the control of the CPU 110, color adjustment is performed in the main unit 101 of the image forming apparatus 100 according to the colorimetric values based on the color pattern imaging results.

  Note that the color adjustment in the main unit 101 of the image forming apparatus 100 can be performed using the RGB values of the color pattern obtained by imaging as described above. In this case, the imaging system 10 images the color pattern together with the reference chart 30 by the imaging device 15. Then, the imaging system 10 performs a process of correcting an error caused by a change in the light source 18 using the RGB value of each colorimetric patch of the reference chart 30 with respect to the RGB value of the color pattern obtained from the captured image. . The corrected RGB value of the color pattern is sent to, for example, the CPU 110 mounted on the main control board of the image forming apparatus 100 and used for color adjustment in the main body unit 101.

  Next, the stop / restart control of the system clock (SCLK) signal by the clock signal generation unit 52 will be described.

  FIG. 12 is a timing chart showing the relationship between signals when a timing signal is supplied from the moving object detection sensor 80 within an imaging (frame) cycle of one screen. FIG. 12 shows the relationship between signals when the timing signal from the moving body detection sensor 80 is supplied to the control unit 50 within the substantial imaging period. FIG. 13 is a schematic diagram showing the positional relationship between the moving object detection sensor 80 and the moving object (recording medium M).

  The timing signal shown in FIG. 12 represents the timing when the recording medium M passes over the moving body detection sensor 80 as shown in FIG. At this time, the recording medium M is moving at a speed V (mm / s) which is a known speed. Further, the interval from the imaging device 15 to the tip of the recording medium M is Lse.

  As shown in FIG. 12, when the timing signal is supplied from the moving body detection sensor 80, the clock signal generator 52 waits for an interrupt at the end of the next frame capture (substantially complete imaging period).

Here, as shown in FIG. 13, the distance from the leading end of the recording medium M to the position of the leading colorimetric patch 1 is Lsp. When the timing signal is supplied from the moving body detection sensor 80 to the control unit 50, the colorimetric patch 1 to be imaged by the imaging device 15 is at a distance of Lse + Lsp from the imaging device 15 and is moving at a constant speed V. It is. That is, the time T for the colorimetric patch 1 to reach the center position of the imaging device 15 after the timing signal is supplied to the clock signal generator 52 is expressed by the following equation.
T = (Les + Lsp) / V

  Therefore, if the next substantial imaging period is started T seconds after the timing signal is supplied to the clock signal generator 52, the colorimetric patch 1 is photographed at the center of the imaging range of the imaging device 15. .

  When the completion of the substantial imaging period is received, the clock signal generator 52 stops supplying the system clock (SCLK) from the clock signal generator 52 to the imaging device 15. At this time, the imaging device 15 enters L (idle period) in the vertical synchronization signal (VSYNC). Note that the idle period is a fixed period. Therefore, it may be stopped at any timing as long as it is within the idle period, but in the present embodiment, for the sake of simplicity, an immediate stop is performed.

  At this time, the clock signal generator 52 stores the time (stop standby time: tw) from when the timing signal is supplied until the system clock (SCLK) to the imaging device 15 is stopped by the frame capture end interrupt ( To be exact, the number of CPU system clocks).

The clock signal generator 52 manages how many pulses the imaging (frame) cycle starts after the supply of the system clock (SCLK) is started (in this embodiment, the idle period ta is entered). Since it is immediately stopped, a period from the start of supply of the system clock (SCLK) to the start of imaging (frame) is set as an idle period ta). Here, assuming that the time ts when the system clock for the image pickup apparatus 15 is stopped, the time T during which the colorimetric patch 1 is predicted to reach the center position of the image pickup apparatus 15 is expressed by the following equation.
T = (Les + Lsp) / V = tw + ts + ta
That is, the system clock stop time ts is expressed by the following equation.
ts = (Les + Lsp) / V−tw−ta

  The clock signal generation unit 52 performs the above calculation processing after stopping the supply of the system clock (SCLK) to the imaging device 15, and restarts the supply of the system clock (SCLK) to the imaging device 15 after the system clock stop time ts has elapsed. To do.

  Accordingly, the clock signal generation unit 52 can cause the colorimetric patch 1 to reach the center of the imaging range of the imaging device 15 after the supply of the system clock (SCLK) is resumed. That is, the imaging device 15 can capture an image of the first frame with the colorimetric patch 1 positioned at the center.

  The second and subsequent colorimetric patches are formed as follows.

As described above, since the frame period is 33.3 [ms], the distance Lp that the recording medium M moves at the speed V can be obtained from the following equation.
Lp = 0.033 * V [mm]

  That is, the color pattern is formed with the second and subsequent patch intervals of the colorimetric patch rows 31 to 34 as the distance Lp at which the recording medium M moves at the speed V. Thereby, the clock signal generation unit 52 sequentially causes the second and subsequent colorimetric patches in the colorimetric patch rows 31 to 34 to reach the center of the imaging range of the imaging device 15 without performing any special timing control. Can do.

  In the present embodiment, the timing signal is directly supplied from the moving object detection sensor 80. However, the present invention is not limited to this, and communication may be performed using a communication standard such as SPI (serial peripheral interface) via another CPU.

  As described above, according to the present embodiment, after the supply of the system clock is stopped, the object to be imaged (measurement of the color pattern formed on the recording medium M) is detected based on the detection of the predetermined relative position by the moving body detection sensor 80. The supply of the system clock to the imaging device 15 is resumed in accordance with the relative movement of the color patch 1). Thereby, since the imaging target (color pattern formed on the recording medium M) and the imaging timing of the imaging device 15 can be synchronized, a target portion in the imaging target can be imaged with high accuracy.

  In the present embodiment, as shown in FIG. 12, upon receiving the completion of the substantial imaging period, the clock signal generation unit 52 immediately stops the supply of the system clock (SCLK) to the imaging device 15. However, it is not limited to this.

  Here, FIG. 14 is a timing chart showing a modified example of the relationship of each signal when a timing signal is supplied from the moving body detection sensor 80 within the imaging (frame) cycle of one screen. For example, as illustrated in FIG. 14, the clock signal generation unit 52 may stop supplying the system clock (SCLK) to the imaging device 15 after entering an idle period that is not a substantial imaging period in the imaging device 15. .

  At this time, the clock signal generator 52 stores the time (stop standby time: tw) from when the timing signal is supplied until the system clock (SCLK) to the imaging device 15 is stopped by the frame capture end interrupt ( To be exact, the number of CPU system clocks).

Further, the clock signal generation unit 52 manages how many pulses after the start of the idle period the system clock (SCLK) is stopped (for convenience, the period ta ″). Since the idle period ta is known, the clock signal generator 52 also manages how many pulses the imaging (frame) cycle starts after the supply of the system clock (SCLK) is started next. (The period from the start of supply of the system clock (SCLK) to the start of imaging (frame) is ta ′). That is, the idle period ta is expressed by the following equation.
ta = ta ′ + ta ″

Here, assuming that the time ts when the system clock for the image pickup apparatus 15 is stopped, the time T during which the colorimetric patch 1 is predicted to reach the center position of the image pickup apparatus 15 is expressed by the following equation.
T = (Les + Lsp) / V = tw + ts + ta ′
That is, the system clock stop time ts is expressed by the following equation.
ts = (Les + Lsp) / V−tw−ta ′

  The clock signal generation unit 52 performs the above calculation processing after stopping the supply of the system clock (SCLK) to the imaging device 15, and restarts the supply of the system clock (SCLK) to the imaging device 15 after the system clock stop time ts has elapsed. To do.

  Accordingly, the clock signal generation unit 52 can cause the colorimetric patch 1 to reach the center of the imaging range of the imaging device 15 after the supply of the system clock (SCLK) is resumed. That is, the imaging device 15 can capture an image of the first frame with the colorimetric patch 1 positioned at the center.

  In the present embodiment, as shown in FIG. 12, the timing signal is received from the moving object detection sensor 80 when the clock signal generator 52 supplies the system clock (SCLK) to the imaging device 15. However, it is not limited to this.

  FIG. 15 is a timing chart showing another modified example of the relationship between signals when a timing signal is supplied from the moving object detection sensor 80 within an imaging (frame) cycle of one screen. For example, FIG. 15 illustrates a state in which the timing signal is supplied while the clock signal generation unit 52 stops supplying the system clock (SCLK) to the imaging device 15 (that is, the imaging device 15 is not capturing an image). Yes.

As described above, the idle period ta is expressed by the following equation.
ta = ta ′ + ta ″

  According to the example shown in FIG. 15, since ta ″ = 0, ta = ta ′.

In this case, assuming that the time ts when the system clock for the image pickup device 15 is stopped after the timing signal is supplied, the time T at which the colorimetric patch 1 is predicted to reach the center position of the image pickup device 15 is expressed by the following equation. .
T = (Les + Lsp) / V = ts + ta ′
That is, the system clock stop time ts is expressed by the following equation.
ts = (Les + Lsp) / V−ta ′

  The clock signal generation unit 52 performs the above calculation processing when the timing signal is supplied after stopping the supply of the system clock (SCLK) to the imaging device 15, and after the system clock stop time ts has elapsed, The supply of the system clock (SCLK) is restarted.

  Accordingly, the clock signal generation unit 52 can cause the colorimetric patch 1 to reach the center of the imaging range of the imaging device 15 after the supply of the system clock (SCLK) is resumed. That is, the imaging device 15 can capture an image of the first frame with the colorimetric patch 1 positioned at the center.

  FIG. 16 is a block diagram illustrating a hardware configuration example of the image forming apparatus 100. As shown in FIG. 16, for example, the image forming apparatus 100 described in the above-described embodiment includes a controller 210, an operation panel 220, a USB (Universal Serial Bus) device 240, an MLB (Media Link Board) 250, And a printer 260 as image forming means.

  The operation panel 220 is a user interface through which a user using the image forming apparatus 100 inputs various settings and displays various information presented to the user.

  The controller 210 is a control device that controls the operation of the image forming apparatus 100. As shown in FIG. 16, the controller 210 includes a CPU (Central Processing Unit) 211, a system memory 213, an HDD 3, a PHY (Physical Layer), and an ASIC (Application Specific Integrated Circuit). 215. The operation panel 220 is connected to the ASIC 215 of the controller 210. The USB device 240, MLB 250, and printer 260 are connected to the ASIC 215 of the controller 210 via the data transfer bus 280.

  In the image forming apparatus 100 described in the present embodiment, some or all of the functional components as the control unit 50 described above are mainly realized by the controller 210. That is, of the functional components described in the present embodiment, a part of the control unit 50 is realized by the ASIC 215 of the controller 210, for example. Further, a part of the control unit 50 is realized by the CPU 211 of the controller 210 executing a predetermined program (software) using the system memory 213, for example.

  The program is recorded in a computer-readable recording medium such as a CD-ROM, a flexible disk (FD), a CD-R, or a DVD in a format that can be installed in the image forming apparatus 100 or an executable format. Provided. Further, the program may be provided by being stored on a computer connected to a network such as the Internet and downloaded to the image forming apparatus 100 via the network. Furthermore, the program may be configured to be provided or distributed via a network such as the Internet. Further, the program may be provided by being incorporated in advance in, for example, the system memory 213 or the HDD 3 in the image forming apparatus 100.

  Although specific embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments as they are, and various modifications and changes are made without departing from the scope of the invention in the implementation stage. It can be embodied.

  For example, the above-described embodiment is an example in which the present invention is applied to the electrophotographic image forming apparatus 100. However, the present invention may be applied to other systems such as a line head ink jet printer and a serial head ink jet printer. The present invention can also be effectively applied to an image forming apparatus.

DESCRIPTION OF SYMBOLS 10 Imaging system 15 Imaging means 52 Control means 55 Colorimetric calculation means 80 Detection means 100 Image forming apparatus 101 Image forming means

Japanese Patent No. 5625666

Claims (12)

An imaging means that moves relative to the imaging object and images the imaging object;
Detecting means for detecting a predetermined relative position between the imaging means and the imaging object;
Control means for switching from stop to supply of a system clock for controlling the timing of imaging start by the imaging means in response to detection of the predetermined relative position by the detection means;
With
The control means, after stopping the supply of the system clock, restarts the supply of the system clock to the imaging means in accordance with the relative movement of the imaging object based on the detection of the predetermined relative position by the detection means. ,
An imaging system characterized by that. The control means predicts the time until the imaging object reaches the imaging object in the center of the imaging range of the imaging means.
The imaging system according to claim 1. The imaging object is a color pattern formed on a recording medium,
A colorimetric calculation unit that calculates a colorimetric value of the color pattern based on an image captured by the imaging unit;
The imaging system according to claim 1 or 2, wherein The detecting means detects a tip of the recording medium on which the imaging object is formed as a predetermined relative position of the imaging object;
The imaging system according to any one of claims 1 to 3, wherein When the control means receives the completion of the imaging period in the imaging means, it stops supplying the system clock to the imaging means.
The imaging system according to any one of claims 1 to 4, wherein The control unit stops supplying the system clock to the imaging unit immediately after receiving the completion of the imaging period in the imaging unit.
The imaging system according to claim 5. The control means stops supplying the system clock to the imaging means after entering an idle period that is not an imaging period in the imaging means after receiving completion of the imaging period in the imaging means.
The imaging system according to claim 5. The control means receives a detection signal of the predetermined relative position by the detection means when supplying a system clock to the imaging means.
The imaging system according to any one of claims 1 to 7, wherein The control means receives the detection signal of the predetermined relative position by the detection means when the supply of the system clock to the imaging means is stopped.
The imaging system according to any one of claims 1 to 7, wherein An imaging system according to any one of claims 1 to 9,
An image forming unit that performs color adjustment based on the imaging result of the imaging system and forms an image;
An image forming apparatus comprising: An imaging method in an imaging system, comprising: an imaging unit that moves relative to an imaging target and images the imaging target; and a detection unit that detects a predetermined relative position of the imaging unit and the imaging target. Because
The supply of the system clock for controlling the timing of the start of imaging by the imaging unit is stopped, and the system clock for the imaging unit is synchronized with the relative movement of the imaging object based on the detection of the predetermined relative position by the detection unit. Resume supply,
An imaging method characterized by the above. An imaging system that moves relative to the imaging object and that includes imaging means for imaging the imaging object and detection means for detecting a predetermined relative position of the imaging means and the imaging object is controlled. Computer
The supply of the system clock for controlling the timing of the start of imaging by the imaging unit is stopped, and the system clock for the imaging unit is synchronized with the relative movement of the imaging object based on the detection of the predetermined relative position by the detection unit. A program that functions as a means to resume supply.