Colorimeter, image forming apparatus, colorimeter method, and program

Abstract

The present invention provides a colorimeter, image forming apparatus, colorimeter, and program capable of accurately determining whether color is being measured at the correct position. [Solution] The colorimeter 1, which performs color measurement by reading a patch formed as an image on a recording medium, includes a control unit 15 that functions as a determination unit that determines whether the color measurement position is appropriate based on the color measurement result of a first position confirmation chart 300 which has a black patch 311 that is black or a low-luminance and low-saturation color similar to black.

Description

【Technical Field】 【0001】 The present invention relates to a color measuring device, an image forming device, a color measuring method, and a program. 【Background Art】 【0002】 Conventionally, as a color measuring device for measuring the color of a test chart, an in-line color measuring device installed inside a printer device that forms a test chart and whose color measurement result is used for calibration of image formation by an image forming device is known. 【0003】 In such an in-line color measuring device, if the color measuring device is not installed at the correct position inside the printer, errors will occur in the color measurement results. Therefore, Patent Document 1 describes a technique in which a chart in which patches having different lightness or chroma are arranged while being shifted by a predetermined pitch in the conveyance direction is measured by a color measuring device, and it is determined whether the color measuring device is performing color measurement at the correct position based on the pattern of the chart and the peak of the color measurement. 【Prior Art Documents】 【Patent Documents】 【0004】 【Patent Document 1】 Japanese Unexamined Patent Application Publication No. 2013-111777 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0005】 However, for example, even when trying to form patches having different lightness or chroma in an image forming device to which a color measuring device is attached, there is a possibility that the patches cannot be accurately formed due to the influence of image formation unevenness of the image forming device. In such a case, an error may occur in determining whether the color measuring device is performing color measurement at the correct position. 【0006】 This invention has been made in view of the above circumstances. Its purpose is to provide a colorimeter, an image forming apparatus, a colorimeter method, and a program that can accurately determine whether color is being measured at the correct position. [Means for solving the problem] 【0007】 To solve the above problems, the invention described in claim 1 is: A colorimeter that measures color by reading a patch formed as an image on a recording medium, The system includes a determination unit that determines whether the measurement position is appropriate based on the color measurement results of a first position confirmation chart which has black patches that are black or a low-luminosity, low-saturation color similar to black. 【0008】 The invention described in claim 2 is a colorimeter according to claim 1, The first position confirmation chart has the black patches repeatedly formed in the CD direction and FD direction at a predetermined period. 【0009】 The invention described in claim 3 is a colorimeter described in claim 2, The first position confirmation chart has substantially the same shape as the black patch and includes a white patch formed by the white area of ​​the recording medium. The black patches and white patches are formed alternately in the CD direction and the FD direction. 【0010】 The invention described in claim 4 is a colorimeter described in claim 3, The system includes an acquisition unit that extracts the color measurement values ​​of the black patch and / or the white patch from the color measurement results of the first position confirmation chart, and acquires statistical data of brightness based on the color measurement values ​​of the black patch and / or the white patch. The determination unit determines whether the color measurement position is appropriate based on the statistical data. 【0011】 The invention described in claim 5 is a colorimeter described in claim 4, The determination unit determines whether the color measurement position is appropriate based on the color measurement results of the first position confirmation chart and the second position confirmation chart, which is composed only of the white patches. 【0012】 The invention described in claim 6 is a colorimeter according to claim 5, The acquisition unit extracts the color measurement values ​​of the white patch from the color measurement results of the second position confirmation chart and obtains statistical data of brightness based on the color measurement values ​​of the white patch. The determination unit determines that the color measurement position is appropriate if the statistical data based on the color measurement values ​​of the white patches on the first position confirmation chart is within a predetermined range compared to the statistical data based on the color measurement values ​​of the white patches on the second position confirmation chart. 【0013】 The invention described in claim 7 is a colorimeter according to any one of claims 1 to 6, A colorimeter head that performs color measurement by reading a patch formed as an image on a recording medium, A moving unit that moves the colorimeter head back and forth in the direction of the CD, It includes a transport unit that transports the recording medium in the direction of the floppy disk. 【0014】 The invention described in claim 8 is a colorimeter described in claim 7, The colorimetric head includes a colorimetric sensor for measuring the color of patches formed as images on the recording medium, and a position sensor for reading positional information of positional patches formed as images on the recording medium. 【0015】 The invention described in claim 9 is a colorimeter described in claim 8, The first position confirmation chart comprises an FD position patch whose primary purpose is to show position information in the FD direction, and a CD position patch whose primary purpose is to show position information in the CD direction. Both the FD position patch and the CD position patch are black or a low-luminosity, low-saturation color that approximates black. 【0016】 The invention described in claim 10 is an image forming apparatus, A color measuring device according to any one of claims 1 to 6, an image forming unit that forms an image of the first position confirmation chart, and is provided with. 【0017】 The invention according to claim 11 is a color measurement method by a color measuring device that performs color measurement by reading a patch formed on a recording medium, and includes a determination step of determining whether the color measurement position is appropriate by measuring a first position confirmation chart including a black patch that is black or a color with low brightness and low chroma approximating black. 【0018】 The invention according to claim 12 is a program, a computer of a color measuring device that performs color measurement by reading a patch formed on a recording medium, is made to function as a determination unit that determines whether the color measurement position is appropriate by measuring a first position confirmation chart including a black patch that is black or a color with low brightness and low chroma approximating black. 【Effect of the Invention】 【0019】 According to the present invention, it is possible to accurately determine whether color measurement is being performed at the correct position. 【Brief Description of the Drawings】 【0020】 [Figure 1] It is a schematic configuration diagram of an embodiment of an image forming apparatus. [Figure 2] It is a block diagram showing the functional configuration of an embodiment of an image forming apparatus. [Figure 3] It is a schematic configuration diagram of an embodiment of a color measuring device. [Figure 4] It is a diagram showing an example of a color measurement chart. [Figure 5] It is a diagram showing an example of the operation of a color measurement head. [Figure 6] It is a diagram showing an example of a first position confirmation chart. [Figure 7] It is a flowchart of a position confirmation job according to the first embodiment. [Figure 8] This graph shows an example of colorimetric data. [Figure 9] This graph shows an example of colorimetric data. [Figure 10] This graph shows an example of colorimetric data. [Figure 11] This graph shows an example of colorimetric data. [Figure 12] This figure shows an example of a second position confirmation chart. [Modes for carrying out the invention] 【0021】 The following description illustrates several embodiments of the present invention with reference to the drawings. The effects and features of the embodiments of the present invention will be understood from the following detailed description and drawings. The following detailed description and drawings are provided for illustrative purposes only and do not limit the scope of the present invention. 【0022】 [First Embodiment] [Image forming apparatus] Figure 1 is a schematic diagram of one embodiment of an image forming apparatus 100 equipped with the colorimeter 1 of the present invention. Figure 2 is a block diagram showing the functional configuration of one embodiment of the image forming apparatus 100 equipped with the colorimeter 1 of the present invention. Figures 1 and 2 show an inkjet recording device, in which the image forming method is an inkjet method, as an example of the image forming apparatus 100. However, the image forming method of the image forming apparatus 100 is not limited to the inkjet method, and may be, for example, an electrophotographic method, and the image forming apparatus 100 may be a laser printer. 【0023】 As shown in Figures 1 and 2, the image forming apparatus 100 comprises a colorimeter 1, a paper feeding unit 2, a transport unit 3, an image forming unit 4, a scanning unit 5, a paper discharge unit 6, a DFE (Digital Front End) 7, a main unit control unit 8, and a main unit operation unit 9. 【0024】 (Paper feed section) The paper feeding unit 2 stores the recording medium. The paper feeding unit 2 has, for example, a tray. Examples of recording media include paper, fabric, and sheet-like resin. Examples of paper include plain paper and coated paper. Sheet paper is preferred as the recording medium. 【0025】 (Transportation section) As shown in Figure 1, the transport unit 3 includes, for example, a feeder board 31, a first transfer drum 32, a transport drum 33, a second transfer drum 34, and an unloading unit 35. 【0026】 {Feeder board, first handover drum} The feeder board 31 transports the recording medium from the paper feeding unit 2 to the first transfer drum 32. The first transfer drum 32 holds one end of the recording medium transported by the feeder board 31, picks it up, and transfers it to the transport drum 33. 【0027】 {transport drum} The transport drum 33 is, for example, cylindrical. The side surface of the transport drum 33 serves as a transport surface that attracts and holds the recording medium. With the recording medium held on the transport surface, the transport drum 33 rotates in one direction around its central axis as the axis of rotation. As a result, the transport drum 33 transports the recording medium, which is attracted and held on the transport surface, along the transport surface. 【0028】 {Second handover drum} The second transfer drum 34 holds one end of the image-forming object conveyed by the transport drum 33, picks it up, and hands it over to the discharge unit 35. 【0029】 {Loading section} The discharge section 35 is the discharge path for the image-formed material, and it transports the image-formed material to the paper discharge section 6 or the colorimeter 1. The discharge section 35 is composed of, for example, a belt and rollers. The transport path in the discharge section 35 may branch along the way, as shown in Figure 1. 【0030】 (Image forming unit) The image forming unit 4 has, for example, one or more head units 41. The image forming unit 4 performs an image forming process to produce an image formed object using an inkjet method. The image forming unit 4 performs normal jobs, color measurement jobs, position confirmation jobs, etc. A normal job is an image forming job that produces a normal image formed object that is not subject to color measurement. A color measurement job is an image forming job that produces an image formed object that is subject to color measurement. The image formed in the color measurement job may be a color measurement chart 200 (see Figure 4), or it may be the same image as the image formed in the normal job. A position confirmation job is an image forming job that produces a position confirmation chart to confirm whether the color measurement device 1 is installed in the correct position. 【0031】 {Head Unit} Each head unit 41 is composed of one or more inkjet heads. The head unit 41 has an ink ejection surface positioned opposite the transport surface of the transport drum 33. The head unit 41 ejects ink onto the recording medium held in the transport drum 33 at an appropriate timing corresponding to the rotation of the transport drum 33 to form an image and produce an image-formed object. 【0032】 In the image forming apparatus 100 illustrated in Figure 1, four head units 41 are arranged at predetermined intervals, starting from the upstream side in the rotational direction of the transport drum 33. The four head units 41 correspond to, for example, four colors of ink: yellow, magenta, cyan, and black. In this embodiment, the image forming apparatus 100, which is an inkjet recording device, is illustrated as performing single-pass (one-pass) image recording with head units 41 extending across the CD direction (Cross Direction) of the image forming area of ​​the recording medium, but it is not limited to this. 【0033】 {Fixing part} The fuser unit 42 is located downstream of the head unit 41 in the transport direction. The fuser unit 42 irradiates energy rays such as ultraviolet light. If the ink is an ultraviolet-curable ink, the ink on the recording medium can be cured by providing the fuser unit 42 that irradiates energy rays. 【0034】 (Scanning section) The scanning unit 5 irradiates the image-forming object with light from a light source and reads the reflected image. The scanning unit 5 is composed of, for example, an inline sensor in which multiple detection elements are arranged along the width direction perpendicular to the transport direction of the recording medium. The image data read by the scanning unit 5 is sent to, for example, the DFE 7, the main unit control 8, etc. 【0035】 (Paper output section) The paper output section 6 discharges the image-formed material. The paper output section 6 has, for example, a tray. 【0036】 (DFE) The DFE (Digital Front End) 7 is an information processing device that converts data transmitted from an external device (not shown) and uses it as image forming data to form an image in the image forming unit 4. The DFE 7 includes a RIP (Raster Image Processor) 71, a color correction unit 72, a colorimetric chart generation unit 73, an ICC profile generation unit 74, and a job generation unit 75. 【0037】 (Main Unit Control) The main control unit 8 provides overall control for each part of the image forming apparatus 100. The main control unit 8 includes a job control unit 81, a transport control unit 82, a color measurement data processing unit 83, and an image quality adjustment unit 84. 【0038】 (Main unit control panel) The main unit operation unit 9 receives user operation instructions for the image forming apparatus 100. The main unit operation unit 9 includes a color measurement job instruction unit 91. 【0039】 [Color measurement device] As shown in Figure 1, the colorimeter 1 is installed inline with the image forming apparatus 100. As shown in Figures 2 and 3, the colorimeter 1 comprises a colorimeter head 11, a moving unit 12, a transport unit 13, a colorimeter data transfer unit 14, and a control unit 15. 【0040】 {Colorimeter Head} The colorimeter head 11 measures the color of the colorimeter chart 200, which is an image formed on the recording medium. As shown in Figure 3, the colorimeter head 11 includes a colorimeter sensor 11a for measuring the color of the colorimeter patch 201 and a position sensor 11b for reading the position information of the position patch. Colorimetering is the measurement of color information, such as measuring color values ​​such as L*a*b* values. As the colorimeter sensor 11a, for example, a spectrophotometer that measures color by spectrally analyzing the reflected light from the colorimeter patch 201 can be used. 【0041】 {Position sensor} The position sensor 11b is mechanically mounted adjacent to the colorimeter sensor 11a, for example, and is movable in the CD direction together with the colorimeter sensor 11a when the colorimeter head 11 moves. The measuring diameter of the position sensor 11b is preferably smaller than the measuring diameter of the colorimeter sensor 11a. This improves the accuracy of position measurement. The measuring diameter of the position sensor 11b is, for example, less than 1 mm. The measuring diameter of the colorimeter sensor 11a is, for example, about 3 to 4 mm. 【0042】 {Moving unit, transport unit, color measurement data transfer unit} The moving unit 12 moves the colorimetric head 11 back and forth in the CD direction. The transport unit 13 transports the recording medium in the FD direction (Feed Direction), which is perpendicular to the CD direction. The colorimetric data transfer unit 14 transfers the colorimetric data to, for example, the DFE 7. 【0043】 {control unit} The control unit 15 can control the operation of not only the colorimetric head 11, the moving unit 12, the transport unit 13, and the colorimetric data transfer unit 14, but also other components. The control unit 15 is a computer and includes, for example, a CPU (Central Processing Unit). The CPU executes various control programs to perform drive control of the measuring device, various calculation processing, etc. 【0044】 (Colorimetric chart) As shown in Figure 4, the colorimetric chart 200 has multiple colorimetric patches 201 and multiple position patches 202A-D and 203A-J... When there is no tilt, the multiple colorimetric patches 201 are arranged parallel to each other in the CD and FD directions. The size of the colorimetric chart 200 is not particularly limited, for example, B2 size (515mm x 728mm). In the colorimetric chart 200 illustrated in Figure 4, the multiple colorimetric patches 201 constitute multiple columns arranged in the CD direction and multiple rows arranged in the FD direction. Specifically, the multiple colorimetric patches 201 constitute columns C1 to C12 and rows R1 to R10. 【0045】 As shown in Figure 4, it is preferable that position patches 202A-D and 203A-J are positioned away from the colorimetric patch 201. This makes it easier for the position sensor 11b to acquire position information of the edges of position patches 202A-D and 203A-J. It is preferable that position patches 202A-D and 203A-J are black. This increases the contrast with the recording medium when the recording medium is white, improving the accuracy of position measurement. It is preferable that position patches 202A-D and 203A-J are rectangular. 【0046】 Multiple position patches consist of CD position patches 202A to D, whose primary purpose is to indicate position information in the CD direction, and FD position patches 203A to J, etc., whose primary purpose is to indicate position information in the FD direction. 【0047】 Multiple FD position patches 203A to J… are positioned on either the left or right side of the colorimetric patch 201, or both sides, spaced apart from each other in the FD direction. Each FD position patch 203A to J is positioned such that its position in the FD direction coincides with each row of the colorimetric patch 201. Specifically, FD position patches 203A, C, E, G, and I… arranged in the FD direction to the left of the colorimetric patch 201 are positioned such that their positions in the FD direction coincide with each odd-numbered row of the colorimetric patch 201. On the other hand, FD position patches 203B, D, F, H, and J… arranged in the FD direction to the right of the colorimetric patch 201 are positioned such that their positions in the FD direction coincide with each even-numbered row of the colorimetric patch 201. In this invention, "left" refers to the left side in the direction of transport of the recording medium, and "right" refers to the right side in the direction of transport of the recording medium. 【0048】 Multiple CD position patches 202A to D are located upstream of the colorimetric patch 201 in the FD direction, and are spaced apart from each other in the CD direction. CD position patch 202A has the same vertical edge position in the CD direction as FD position patches 203A, C, E, G, and I… located to the left of the colorimetric patch 201. CD position patch 202D has the same vertical edge position in the CD direction as FD position patches 203B, D, F, H, and J… located to the right of the colorimetric patch 201. The vertical edge position refers to the position of the edge of the position patch along the FD direction. CD position patches 202A and D are used, for example, to control the colorimetric start position 204 of the colorimetric patch 201 in the first row R1. 【0049】 CD position patches 202B and 202C align in the CD direction with the columns at both ends of colorimetric patch 201. Specifically, CD position patch 202B aligns in the CD direction with column 1 C1 of colorimetric patch 201. CD position patch 202C aligns in the CD direction with column 12 C12 of colorimetric patch 201. 【0050】 By providing the colorimetric chart 200 with multiple CD position patches 202A-D and FD position patches 203A-J, the accuracy of automatic color measurement can be improved even if the colorimetric chart 200 is tilted. 【0051】 For example, as shown in Figure 5, the control unit 15 moves the colorimetric head 11 from its home position a, through position b where FD position patches 203A, C, E, G, and I are aligned in the FD direction, to position c where FD position patches 203B, D, F, H, and J are aligned in the FD direction. At this time, the position sensor 11b reads the position information of each left edge of CD position patches 202A to D. The control unit 15 then calculates the amount of movement of the colorimetric head 11 required for each colorimetric patch 201 from the position information of CD position patches 202B and C. The control unit 15 then returns the colorimetric head 11 to its home position a. 【0052】 Next, the control unit 15 moves the colorimetric head 11 to position b, then transports the recording medium in the FD direction to move it to the upper position of the first row of colorimetric patches 201. After that, the control unit 15 returns the colorimetric head 11 to its home position a and acquires the position information of the left edge of the FD position patch 203A. 【0053】 The control unit 15 then calculates the tilt amount of the colorimetric patch 201 from the difference in position information of the left edge of the CD position patch 202A and the FD position patch 203A, and the amount of recording medium transported. The control unit 15 also determines the starting position of colorimetric measurement in the FD direction of the colorimetric head 11 based on the calculated tilt amount of the colorimetric patch 201. By repeating the calculation of the tilt amount of the colorimetric patch 201 and the determination of the starting position of colorimetric measurement in the FD direction for each row, the reading position of the colorimetric sensor 11a is less likely to shift even if the colorimetric chart 200 is tilted. As a result, errors in the measured color values ​​are less likely to occur, and the accuracy of colorimetric measurement can be improved. 【0054】 [First position confirmation chart] The first position confirmation chart 300 is one of the position confirmation charts formed by the image forming unit 4 in a position confirmation job. As shown in Figure 6, the first position confirmation chart 300 comprises a plurality of position patches 202A to D, 203A to, and a black and white pattern 310. The black and white pattern 310 is composed of a plurality of black patches 311 and white patches 312. The black patches 311 are roughly rectangular patches in which a*b*L* is 0 or approximately 0. The white patches 312 are patches that are roughly the same shape as the black patches 311, and are colored by the color of the recording medium itself, without the addition of ink. 【0055】 In the black and white pattern 310, multiple black patches 311 and white patches 312 are arranged alternately in the CD direction and FD direction to form a grid pattern. For example, if the recording medium is B2 size, the black and white pattern 310 is composed of 44 rows x 37 columns = 1628 patches, of which there are 814 black patches 311 and 814 white patches 312. By measuring the color of the black and white pattern 310, in which black patches 311 and white patches 312 are arranged alternately in this way, if the colorimeter 1 is not measuring at the correct position, the color measurement result of the black patches 311 will be more easily affected by the white patches 312 (or vice versa). Therefore, it becomes easy to determine whether the colorimeter 1 is measuring at the correct position or not. 【0056】 [Color measurement position determination process] The color measurement position determination process using such a first position confirmation chart 300 will be explained based on the flowchart in Figure 7. The color measurement position determination process is performed, for example, when installing the colorimeter 1 or when adjusting or inspecting when using different recording media. 【0057】 First, the image forming unit 4 forms a first position confirmation chart 300 image on the recording medium (step S1). The main control unit 8 transports the recording medium on which the first position confirmation chart 300 has been formed to the colorimeter 1 (step S2), and starts color measurement by the colorimeter 1. 【0058】 First, the control unit 15 moves the colorimeter head 11 from position a to position b and then to position c. At this time, the position sensor 11b reads the position information of the left edge of each CD position patch 202A to D. From the position information of the left edges of CD position patches 202B and C, the control unit 15 calculates the amount of movement of the colorimeter head 11 required for each black patch 311 or white patch 312 (step S3). After that, the control unit 15 returns the colorimeter head 11 to its home position at position a. 【0059】 The control unit 15 moves the colorimetric head 11 alternately in the CD direction and the FD direction, thereby repeatedly measuring the color of the black patch 311 and the white patch 312 and calibrating the colorimetric sensor 11a (steps S4 to S8). In this embodiment, the colorimetric device 1 is equipped with a calibration plate (not shown) at the home position of position a. Therefore, the control unit 15 calibrates the colorimetric sensor 11a every even row (step S7). Once colorimetric measurement is completed up to the last row (steps S5, S8; Yes), the colorimetric data transfer unit 14 transfers and saves the colorimetric data to, for example, the colorimetric data processing unit 83 (step S9). 【0060】 The control unit 15 extracts the brightness component from the color measurement data to obtain statistical data such as the average value, maximum value, minimum value, and range (difference between the maximum and minimum values) of brightness for the black patch 311 and the white patch 312. In this way, the control unit 15 functions as an acquisition unit that extracts the color measurement values ​​of the black patch 311 and / or the white patch 312 from the color measurement results of the first position confirmation chart 300 and obtains statistical data of brightness based on the color measurement values ​​of the black patch 311 and / or the white patch 312. 【0061】 The control unit 15 performs an analysis based on the statistical data (step S10) and determines whether the color measurement position of the colorimeter 1 is appropriate (step S11). The control unit 15 determines that the color measurement position of the colorimeter 1 is appropriate if the value in the statistical data is within a predetermined range. In this way, the control unit 15 functions as a determination unit that determines whether the color measurement position is appropriate based on the color measurement result of the first position confirmation chart. 【0062】 Steps S10 and S11 will be explained in detail. Figure 8 is a graph plotting the colorimetric data of the white patch 312, with the horizontal axis being rows and the vertical axis being lightness L*. Figure 9 is a graph plotting the colorimetric data of the black patch 311, with the horizontal axis being rows and the vertical axis being lightness L*. Figure 10 is a graph plotting the colorimetric data of the white patch 312, with the horizontal axis being columns and the vertical axis being lightness L*. Figure 11 is a graph plotting the colorimetric data of the black patch 311, with the horizontal axis being columns and the vertical axis being lightness L*. 【0063】 If the colorimeter 1 is not measuring color at the correct position, when the colorimeter sensor 11a moves by the width of one patch to measure either the black patch 311 or the white patch 312, it may measure across the other patch. In this case, the colorimeter result of the black patch 311 may be affected by the white patch 312, causing its brightness to increase, or the colorimeter result of the white patch 312 may be affected by the black patch 311, causing its brightness to decrease. In such cases, as shown by the dotted lines in Figures 8 and 10, an abnormal value is generated in the colorimeter result of the white patch 312 where the brightness L* is extremely low compared to other colorimeter results. Alternatively, as shown by the dotted lines in Figures 9 and 11, an abnormal value is generated in the colorimeter result of the black patch 311 where the brightness L* is extremely high compared to other colorimeter results. Therefore, depending on whether the values ​​in the statistical data are within a predetermined range, the colorimeter data processing unit 83 can determine whether the colorimeter position of the colorimeter 1 is appropriate. 【0064】 If the color measurement position of the colorimeter 1 is inappropriate (step S11; No), the control unit 15 notifies the user of the color measurement result and the correction of the color measurement position using a known notification unit (not shown) (step S12). Based on the color measurement result, the user checks the mounting position of the colorimeter 1 and the presence or absence of dust in the transport unit 3. On the other hand, if the color measurement position of the colorimeter 1 is appropriate (step S11; Yes), there is no need to correct the color measurement position, and the position confirmation job is terminated. 【0065】 [Effects of the First Embodiment] The colorimeter 1 according to the first embodiment includes a control unit 15 that functions as a determination unit that determines whether the color measurement position is appropriate based on the color measurement result of a first position confirmation chart 300 which has a black patch 311 that is black or a low-luminance and low-saturation color that approximates black. In this invention, "low luminance" refers to a luminance L* of, for example, 15 or less, and "low saturation" refers to a saturation C* of, for example, 10 or less. As described above, the black patch 311 is low-luminance and low-saturation, and so-called color unevenness hardly occurs, so the colorimeter 1 can accurately confirm whether it is measuring color at the correct position without being affected by these factors. 【0066】 Furthermore, as a method to eliminate the effects of color unevenness, a configuration in which a recording medium with a chart that has been confirmed to be free of color unevenness is stored in advance is also conceivable. However, in this configuration, it is necessary to store the recording medium with the chart that has been pre-formed and confirmed to be free of color unevenness in the paper feed unit 2, etc., which is time-consuming. On the other hand, according to the configuration of this embodiment, in order to confirm whether color measurement is being performed at the correct position using the easily formed black patch 311, it is possible to easily confirm whether the color measuring device 1 is performing color measurement at the appropriate position, especially in a configuration in which the color measuring device 1 is installed inside the image forming apparatus 100. 【0067】 Furthermore, in the colorimeter 1 according to the first embodiment, the first position confirmation chart 300 has black patches 311 repeatedly formed in the CD direction and FD direction at a predetermined period. With this configuration, if there is an abnormality in the colorimeter result, the abnormality will appear at a predetermined period, making it easier to identify the nature of the abnormality. 【0068】 Furthermore, in the colorimeter 1 according to the first embodiment, the first position confirmation chart 300 includes a white patch 312 which is substantially the same shape as the black patch 311 and is formed by the white area of ​​the recording medium. The black patch 311 and the white patch 312 are arranged alternately in the CD direction and the FD direction. With this configuration, if the colorimeter position of the colorimeter 1 is not appropriate, when reading one patch, it will be affected by the other patch, making detection easier. 【0069】 Furthermore, in the colorimeter 1 according to the first embodiment, the control unit 15 functions as an acquisition unit that acquires statistical data of brightness based on the measured color value of the black patch 311 and / or the measured color value of the white patch 312 from the colorimeter results of the first position confirmation chart 300. The determination unit then determines whether the colorimeter position is appropriate based on the statistical data. As described above, the black patch 311 has a brightness of zero or an approximate value of zero. Also, since the white patch 312 is the white area of ​​the recording medium, its brightness is a predetermined constant value. Therefore, if the colorimeter position of the colorimeter 1 is inappropriate and the reading of one patch is affected by the other patch, detection becomes easier. 【0070】 In the above example, the control unit 15 calibrates the colorimeter sensor 11a every even-numbered row, but this is not the only configuration. That is, after calibrating the colorimeter sensor 11a when measuring the black patch 311 and white patch 312 of the first row, the system may only measure the color of each row to acquire the colorimeter data. 【0071】 [Second Embodiment] Next, a colorimeter 1 according to the second embodiment will be described. In the following description, the same reference numerals are used for components similar to those in the colorimeter 1 according to the first embodiment, and detailed explanations will be omitted. The colorimeter 1 according to the second embodiment differs from the colorimeter 1 according to the first embodiment in that it determines whether the color measurement position of the colorimeter 1 is appropriate by measuring the color of not only the first position confirmation chart 300 but also the second position confirmation chart 400. 【0072】 As shown in Figure 12, the second position confirmation chart 400 does not have black patches 311, but only multiple position patches and white patches 312. Therefore, for example, if the recording medium is B2 size, the second position confirmation chart 400 has 44 rows × 37 columns = 1628 white patches 312. In Figure 12, dotted lines are shown on the recording medium to represent the white patches 312, but in reality, the image forming unit 4 does not form images of these dotted lines. 【0073】 If the recording medium on which the first position confirmation chart 300 is formed and the recording medium on which the second position confirmation chart 400 is formed are of the same type, the color measurement results of both white patches 312 should be approximately identical. Therefore, by measuring the color of such a second position confirmation chart 400 and comparing it with the color measurement data of the white patches 312 of the first position confirmation chart 300, the control unit 15 can more accurately determine whether the colorimeter 1 is measuring at the correct position. 【0074】 [Effects of the second embodiment] As described above, in the colorimeter 1 according to the second embodiment, the control unit 15 determines whether the color measurement position is appropriate based on the color measurement results of the first position confirmation chart 300 and the second position confirmation chart 400, which is composed only of white patches 312. With this configuration, statistical data on the brightness of the white patches 312, which are not affected by the black patches 311, can be obtained from the color measurement results of the second position confirmation chart 400. Therefore, the influence of the black patches 311 on the white patches 312 of the first position confirmation chart 300 becomes clearer, and it becomes clearer whether the color measurement position is appropriate. 【0075】 In the above description, the first position confirmation chart 300 is color-measured before the second position confirmation chart 400 is color-measured. However, this is not limited to this procedure, and it is also possible to color-measure the second position confirmation chart 400 before the first position confirmation chart 300. 【0076】 Furthermore, in the above example, the recording medium was given as being B2 size, and therefore the position confirmation chart was assumed to have 44 rows x 37 columns = 1628 patches. However, the number of patches in the position confirmation chart may vary depending on the size of the recording medium. Nevertheless, it is preferable to determine whether the color measurement position of the colorimeter 1 is appropriate based on color measurement data consisting of the color measurement results of a larger number of patches, as this will yield more accurate results. 【0077】 Furthermore, while the above describes examples in which hard disks, semiconductor non-volatile memory, etc., are used as ROMs as computer-readable media for the program according to the present invention, the invention is not limited to these examples. Portable recording media such as CD-ROMs can also be used as other computer-readable media. In addition, carrier waves can be used as a medium for providing the data of the program according to the present invention via a communication line. [Explanation of symbols] 【0078】 1 Colorimetric device 11 Colorimeter head 12. Mobile section 13 Conveying section 15 Control Unit (Determination Unit, Acquisition Unit) 300 Chart for confirming the first position 311 Black Patch 312 White Patch 400 Chart for confirming the second position

Claims

[Claim 1] A colorimeter that measures color by reading a patch formed as an image on a recording medium, A colorimeter comprising a determination unit that determines whether the color measurement position is appropriate based on the color measurement result of a first position confirmation chart having black patches which are black or a low-luminosity and low-saturation color similar to black. [Claim 2] The first position confirmation chart is a colorimeter according to claim 1, wherein the black patches are repeatedly formed in the CD direction and FD direction at a predetermined period. [Claim 3] The first position confirmation chart has substantially the same shape as the black patch and includes a white patch formed by the white area of ​​the recording medium. The colorimeter according to claim 2, wherein the black patch and the white patch are formed alternately in the CD direction and the FD direction. [Claim 4] The system includes an acquisition unit that extracts the color measurement values ​​of the black patch and / or the white patch from the color measurement results of the first position confirmation chart, and acquires statistical data of brightness based on the color measurement values ​​of the black patch and / or the white patch. The colorimeter according to claim 3, wherein the determination unit determines whether the color measurement position is appropriate based on the statistical data. [Claim 5] The colorimeter according to claim 4, wherein the determination unit determines whether the color measurement position is appropriate based on the color measurement results of the first position confirmation chart and the second position confirmation chart composed only of the white patches. [Claim 6] The acquisition unit extracts the color measurement value of the white patch from the color measurement result of the second position confirmation chart and obtains statistical data of brightness based on the color measurement value of the white patch. The colorimeter according to claim 5, wherein the determination unit determines that the color measurement position is appropriate if the statistical data based on the color measurement value of the white patch of the first position confirmation chart is within a predetermined range with respect to the statistical data based on the color measurement value of the white patch of the second position confirmation chart. [Claim 7] A colorimeter head that performs color measurement by reading a patch formed as an image on a recording medium, A moving unit that moves the colorimeter head back and forth in the direction of the CD, A colorimeter according to any one of claims 1 to 6, comprising a transport unit for transporting a recording medium in the FD direction. [Claim 8] The colorimeter according to claim 7, wherein the colorimeter head comprises a colorimeter sensor for measuring the color of patches formed as images on a recording medium, and a position sensor for reading position information of position patches formed as images on a recording medium. [Claim 9] The first position confirmation chart comprises an FD position patch whose primary purpose is to show position information in the FD direction, and a CD position patch whose primary purpose is to show position information in the CD direction. The colorimeter according to claim 8, wherein both the FD position patch and the CD position patch are black or a low-luminosity and low-saturation color that approximates black. [Claim 10] A colorimeter according to any one of claims 1 to 6, An image forming unit that forms an image of the first position confirmation chart, An image forming apparatus equipped with the following features. [Claim 11] A colorimetric method using a colorimetric device that measures color by reading a patch formed as an image on a recording medium, A color measurement method comprising a determination step of determining whether the color measurement position is appropriate by measuring the color of a first position confirmation chart that has black patches which are black or a low-luminosity and low-saturation color similar to black. [Claim 12] The computer of a colorimeter that performs color measurement by reading the patch formed as an image on the recording medium, A program that functions as a determination unit to determine whether the measurement position is appropriate by measuring the color of a first position confirmation chart equipped with black patches that are black or a low-luminosity, low-saturation color similar to black.

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