Image forming apparatus, maintenance method for color measuring unit, and chart printing paper for color measurement

Abstract

To facilitate execution of maintenance of in-line color measurement unit of an image forming apparatus.SOLUTION: An image forming apparatus 10 comprises an image forming unit 12, an in-line color measurement unit 16, and an image processing unit 15 that executes color adjustment on the basis of a color measurement value. The image processing unit 15 combines pieces of divided color measurement data 41a obtained by measuring the colors of a plurality of color patterns 34 obtained by dividing a chart having a common arrangement with that of a color chart 31. The image processing unit 15 can acquire color measurement values of a plurality of color patches 30 formed on the color chart from the plurality of pieces of divided color measurement data 41a combined with each other.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus, a maintenance method for a color measurement unit, and a color measurement chart printing paper. [Background technology]

[0002] Conventionally, there has been known an image forming apparatus in which a color chart printed in an image forming unit is passed through an in-line colorimetric unit for color measurement, and color adjustment is performed based on the colorimetric values of a large number of color patches included in the color chart.

[0003] Various devices have been proposed for color measurement units that measure the color of a large number of color patches. For example, the color measurement device described in Patent Document 1 listed below claims that the color measurement head can move without stopping during color measurement, thereby enabling efficient color measurement of a large number of color patches. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-283852 Summary of the Invention [Problem to be solved by the invention]

[0005] In image forming apparatuses equipped with an in-line colorimeter, it may be impossible to measure the color of a color chart due to a malfunction of the in-line colorimeter or maintenance such as calibration. In such cases, it may be possible to measure the color using an external colorimeter to enable printing. However, the size of a color chart that can be measured with an external colorimeter is often smaller than the size that can be measured with an in-line colorimeter. If color adjustment is performed by measuring the color of multiple color patches one by one multiple times using such an external colorimeter, the amount of work required for color measurement and color adjustment can become significantly increased.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an image forming apparatus that allows easy maintenance of an in-line colorimetric unit, a maintenance method for the colorimetric unit, and chart printing paper that is easy to use for maintenance. [Means for solving the problem]

[0007] To solve the above problems, the image forming apparatus of the present invention includes an image forming unit that prints a color chart, an inline colorimetric unit that measures the color patches of the color chart, and an image processing unit that performs color adjustment based on the colorimetric values of the color patches. The image processing unit then combines multiple pieces of split colorimetric data obtained by measuring multiple color patterns obtained by dividing a chart in which color patches are arranged in common with the color chart. Furthermore, the image forming unit can obtain the colorimetric values of the multiple color patches formed on the color chart from the combined multiple pieces of split colorimetric data.

[0008] The maintenance method for the colorimetry unit of the present invention involves printing a color chart, measuring the color patches of the color chart with an in-line colorimetry unit, and performing color adjustments based on the colorimetric values of the color patches. This maintenance method involves measuring multiple color patterns obtained by dividing a chart with the same layout as the color chart, combining the divided colorimetric data to obtain the colorimetric values of the multiple color patches. Furthermore, this maintenance method determines whether maintenance of the in-line colorimetry unit is necessary by comparing the colorimetric values obtained from the color chart with the colorimetric values obtained from the multiple color patterns.

[0009] The color measurement chart printed paper of the present invention is a color measurement chart printed paper on which a color chart having a plurality of color patches is printed. The color chart has a plurality of separable color patterns each having a plurality of color patches. The color chart is further cut between the plurality of color patterns to form a plurality of pattern-printed papers on which the color patterns are printed. [Effects of the Invention]

[0010] According to the present invention, it is possible to facilitate maintenance of an in-line color measurement unit of an image forming apparatus. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram illustrating the configuration of an image forming apparatus according to an embodiment of the present invention. [Figure 2] 1 is a schematic block diagram of an image forming apparatus according to an embodiment of the present invention. [Figure 3] 1A is a diagram showing a chart-printed paper according to an embodiment of the present invention, and FIG. 1B is a diagram showing a pattern-printed paper produced by cutting the chart-printed paper. [Figure 4] 1A is a diagram illustrating a method for measuring colors in an in-line color measurement unit according to an embodiment of the present invention, and FIG. 1B is a diagram illustrating a method for measuring colors of pattern-printed paper in an external color measurement unit. [Figure 5] 1A is a diagram showing an example of one pattern-printed paper in an embodiment of the present invention, and FIG. 1B is a diagram showing an example of colorimetric division data of the pattern-printed paper. [Figure 6] 10A is a diagram showing an example of another pattern-printed paper in an embodiment of the present invention, and FIG. 10B is a diagram showing an example of colorimetric division data of the pattern-printed paper. [Figure 7] 10 is a flowchart showing a procedure for acquiring colorimetric values of all color patches from colorimetric data of an in-line colorimetric unit in an image processing unit according to an embodiment of the present invention. [Figure 8] FIG. 1A shows an example of a color chart in an embodiment of the present invention, FIG. 1B shows an example of colorimetric data of the color chart, and FIG. 1C shows an example of colorimetric data after discarding the colorimetric values of the cutting area. [Figure 9] 10 is a flowchart showing a procedure for acquiring colorimetric values of all color patches from colorimetric division data of an external colorimetric unit in an image processing unit according to an embodiment of the present invention. [Figure 10]FIG. 1A shows an example of one color pattern in an embodiment of the present invention, FIG. 1B shows an example of the other color pattern, FIG. 1C shows an example of colorimetric split data for each color pattern, and FIG. 1D shows an example of colorimetric split data for each color pattern. [Figure 11] FIG. 1A shows an example in which two pieces of colorimetric split data are combined and rearranged in an embodiment of the present invention, and FIG. 1B shows another example in which two pieces of colorimetric split data are combined and rearranged. [Figure 12] FIG. 1A shows a chart-printed paper according to a modified example of the present invention, FIG. 1B shows one pattern-printed paper produced by cutting the chart-printed paper, and FIG. 1C shows the other pattern-printed paper produced by cutting the chart-printed paper. [Figure 13] 10A is a diagram showing a chart printing paper according to another modified example of the present invention, and FIG. 10B is a diagram showing a chart printing paper according to another modified example. [Figure 14] FIG. 10 is a diagram showing a chart printing paper according to another modified example of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] An example of an image forming apparatus according to an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described below with reference to the drawings. In the following embodiment, a single-pass inkjet printer will be used as an example. However, the present invention is not limited to the following example. In each of the drawings described below, common components are designated by the same reference numerals.

[0013] [First embodiment] Fig. 1 is a schematic diagram of an image forming apparatus according to this embodiment, and Fig. 2 is a block diagram thereof. The image forming apparatus 10 includes a DFE (Digital Front End) 11, an image forming unit 12, an operation unit 13, a control unit 14, an image processing unit 15, an in-line colorimetric unit 16, and an external colorimetric unit 17. The DFE 11 is a print controller that generates image data for print images based on print jobs received from external devices such as client PCs. The DFE 11 processes the image data included in the print job using a Raster Image Processor (RIP), corrects the colors, and generates image data in bitmap format. The DFE 11 generates image data of the color chart 31 for color measurement. This image data may be data that has been created and saved in advance. The generated image data may be subjected to image processing such as correction processing according to unevenness of the print head by the image processing unit 15 described later.

[0014] Under the control of the control unit 14, the image forming unit 12 uses various settings of the operation unit 13 to print an image on paper from the paper feed unit 18 based on the image data generated by the DFE 11, and discharges the paper to the paper discharge unit 19. The image forming unit 12 includes a print engine 25 and an in-line sensor 24. The print engine 25 includes a main cylinder 21, a head unit 22 (CMYK), and a UV irradiation unit 23.

[0015] The print engine 25 then forms an image on the paper conveyed by the main cylinder 21 using UV ink from the head unit 22, and hardens the image using the UV irradiation unit 23. The in-line sensor 24 reads the printed image to inspect it for defects, etc., and discharges the image to the paper discharge unit 19. In this image forming unit 12, image data of a color chart 31 (see A in FIG. 3) for color measurement generated by the DFE 11 is printed on paper, and a chart printing paper 32 is produced. This chart printing paper 32 is transported directly and continuously from the image forming unit 12 to the in-line colorimetric unit 16 based on a purge processing signal from the control unit 14 .

[0016] Here, the chart printing paper 32 will be described. Fig. 3A shows the chart printing paper 32 on which a color chart is printed. The color chart 31 of this embodiment is a chart in which a plurality of color patches 30 are arranged vertically and horizontally. A margin 33 is provided around the periphery of the color chart 31. A large number of rectangular color patches 30 are arranged in a matrix on the color chart 31. In this embodiment, the color chart 31 has color patches 30 for all the colors included in the image data.

[0017] In this color chart 31, a large number of color patches 30 are arranged and separated into a plurality of color patterns 34. The plurality of color patterns 34 are arranged so as to be separable from one another. The large number of color patches 30 all have the same shape. The chart-printed paper 32 is cut between the plurality of color patterns 34 to form a plurality of pattern-printed papers 35 on which the color patterns 34 are printed. As shown in Fig. 3B, the chart-printed paper 32 of this embodiment has two pattern-printed papers 35 formed thereon.

[0018] The pattern-printed paper 35 on which the color pattern is printed is formed by cutting the chart-printed paper 32. Therefore, the shape of the color patches 30 is the same among the color patterns 34 of the multiple pattern-printed papers 35, and the shape of the color patches 30 within each color pattern 34 is also the same. In other words, the multiple pattern-printed papers 35 have multiple color patterns 34 obtained by dividing a chart with the same arrangement as the color chart 31. In this embodiment, the multiple color patterns 34 are cut so that the number of vertical and horizontal arrangements of the color patches 30 of each color pattern 34 is the same among the multiple color patterns 34.

[0019] As shown in FIG. 3A, the chart printing paper 32 is provided with cutting marks 36 to indicate the positions where the plurality of color patterns 34 should be cut. Furthermore, the cutting mark 36 of this embodiment has a cutting area 36a provided between two color patterns 34. The cutting area 36a is provided between the color patterns 34 with a width that is an integral multiple of the width of the color patch 30. Generally, it is preferable that the cutting area 36a be colorless. Furthermore, in the cutting marks 36 of this embodiment, cutting lines 36b are drawn between the color patterns 34. These cutting lines 36b are drawn continuously so as to surround the periphery of each color pattern 34. The two pattern-printed papers 35 shown in Fig. 3B are produced by cutting the chart-printed paper 32 along the cutting lines 36b.

[0020] Returning to FIG. 1 , the operation unit 13 of the image forming apparatus 10 inputs various settings, information, and the like. For example, the operation unit 13 inputs various settings for adjusting the print engine 25. The operation unit 13 also inputs information, commands, and the like for creating an ICC profile. Furthermore, the operation unit 13 inputs divided colorimetric data 41a of a large number of color patches 30 measured by the external colorimetric unit 17.

[0021] The control unit 14 controls each unit of the image forming unit 12. The control unit 14 performs job control to execute a print job. The control unit 14 also performs purge processing to perform colorimetry in the in-line colorimetry unit 16. This purge processing is a process of purging the chart printing paper 32 discharged from the image forming unit 12 so that it is not conveyed to the in-line colorimetry unit 16.

[0022] The in-line colorimetric unit 16 measures the color of all of the color patches 30 on the color chart 31 and transfers the colorimetric data 41 to the image processing unit 15 . The in-line colorimetric unit 16 is an automatic paper-feeding colorimeter. Chart printing paper 32 is fed into the in-line colorimetric unit 16 directly and continuously from the image forming unit 12. Therefore, the in-line colorimetric unit 16 has a paper feed width that is the same as the maximum width of paper that can be fed through the image forming unit 12. Since the image forming apparatus 10 of this embodiment is capable of printing on large-sized paper exceeding 320 mm, the in-line color measurement unit 16 also has a paper transport width exceeding 320 mm.

[0023] FIG. 4A is a diagram illustrating a color measurement method in the in-line color measurement unit 16 according to this embodiment. That is, the in-line colorimetric unit 16 measures the color of each color patch 30 by moving the colorimetric head in a direction perpendicular to the paper transport direction D1 while feeding the chart printing paper 32 in the paper transport direction D1. 4A shows the paper transport direction D1 and colorimetry direction of the chart printing paper 32 in the in-line colorimetry unit 16. In the in-line colorimetry unit 16, the chart printing paper 32 is transported line by line of the color chart 31. The colorimetry head moves in the opposite direction for each line to measure the color.

[0024] 3A, the chart printing paper 32 of this embodiment has colorless cutting areas 36a between the color patterns 34, each having a width that is an integral multiple of the width of the color patch 30. Therefore, the inline colorimetric unit 16 measures the color of each color patch 30 in the color pattern 34, and also measures the cutting areas 36a. The colorimetric data of the chart printing paper 32 includes these colorimetric values. The colorimetric data 41 of all the color patches 30 acquired by the in-line colorimetric unit 16 is transferred to the image processing unit 15 .

[0025] The external colorimetric unit 17 is an automatic paper-feeding colorimeter and is provided separately from the inline colorimetric unit 16. The external colorimetric unit 17 may be provided integrally with the image forming apparatus 10, but in this embodiment it is provided separately. The external colorimetric unit 17 in this embodiment has a paper transport width narrower than that of the inline colorimetric unit 16. The paper transport width of the external colorimetric unit 17 is 320 mm or less. The external colorimetric unit 17 measures the color of all of the multiple color patches 30 in the multiple color patterns and transfers the colorimetric data 41 to the image processing unit 15.

[0026] 4B shows the paper transport direction D2 and color measurement direction of the pattern-printed paper 35 in the external colorimetric unit 17. The multiple pattern-printed papers 35 are formed by cutting the chart-printed paper 32 in a direction perpendicular to the paper transport direction D1 of the chart-printed paper 32. The paper transport direction D2 of each pattern-printed paper 35 during color measurement in the external colorimetric unit 17 is perpendicular to the paper transport direction D1 during color measurement of the chart-printed paper 32. The paper transport width of each pattern-printed paper 35 is 320 mm or less. In this embodiment, the paper transport direction D2 of the pattern-printed paper 35 after cutting is depicted in the area of each pattern-printed paper 35 that corresponds to the margin of each pattern-printed paper 35.

[0027] As shown in FIG. 4B, the external colorimetric unit 17 measures the color of each color patch 30 by moving the colorimetric head in a direction perpendicular to the paper transport direction D2 while passing the pattern-printed paper 35 in the paper transport direction D2. In the external colorimetric unit 17, the pattern-printed paper 35 is conveyed for each line of the color pattern 34, and the colorimetric head moves in the opposite direction for each line, thereby performing colorimetry.

[0028] Figures 5A and 6A show examples of multiple pattern-printed papers, and Figures 5B and 6B show examples of the respective divided colorimetric data. In the inline colorimetry unit 16 and external colorimetry unit 17 of this embodiment, the colorimetry values of each color patch 30 are acquired as values digitized in the Lab color space. Each pattern-printed sheet 35 shown in Figures 5A and 6A is colorimetrically measured, thereby acquiring divided colorimetry data 41a shown in Figures 5B and 6B. In this divided colorimetry data, the colorimetry values are recorded in the order of colorimetry by sequentially measuring the colorimetry of a large number of color patches 30 along the paper transport direction D2 and the movement direction of the colorimetry head.

[0029] 1, the image processing unit 15 appropriately processes the image data generated by the DFE 11 and transfers it to the print engine 25 of the image forming unit 12. The image processing unit 15 also processes and utilizes the colorimetric data 41 acquired by the inline colorimetric unit 16 and the divided colorimetric data 41a acquired by the external colorimetric unit 17. Furthermore, the image processing unit 15 compares the colorimetric data 41 acquired by the inline colorimetric unit 16 and the divided colorimetric data 41a acquired by the external colorimetric unit 17 with each other and with a specified value or a set value in the comparison unit 15a. This allows the image processing unit 15 to evaluate each of the colorimetric units 16 and 17.

[0030] Here, when using the colorimetric data 41 acquired by the inline colorimetric unit 16, the entire color chart 31 is printed on a single sheet of chart printing paper 32. Therefore, the image processing unit 15 can perform data processing by matching the setting value at each coordinate of the color chart 31 with the colorimetric value at that coordinate in the colorimetric data 41 of the inline colorimetric unit 16. Here, the coordinates refer to the vertical and horizontal positions of each color patch 30. The colorimetric data 41 of the inline colorimetric unit 16 includes the colorimetric values of the cutting areas 36a between the color patterns 34 as well as the colorimetric values of each color patch 30. Therefore, the image processing unit 15 can obtain the colorimetric values corresponding to all the color patches 30 of the color chart 31 by discarding the colorimetric values of the cutting areas 36a.

[0031] When using the divided colorimetric data 41a acquired by the external colorimetric unit 17, the color chart 31 is divided into multiple color patterns 34 and printed on multiple pattern-printed sheets 35. Therefore, the image processing unit 15 combines the divided colorimetric data 41a of the multiple pattern-printed sheets 35. Furthermore, the image processing unit 15 rearranges the colorimetric values in the multiple divided colorimetric data 41a in the order of the multiple color patches 30 on the color chart 31. This allows the image processing unit 15, like the inline colorimetric unit 16, to acquire the measurement values of all the color patches 30 on the color chart 31.

[0032] Next, the operation of the image forming apparatus 10 will be described. Image forming apparatus 10 generates image data in DFE 11 based on a print job received from an external device. Then, image forming apparatus 10 prints an image in image forming unit 12 under the control of various settings via operation unit 13 and control by control unit 14. During operation, a color chart 31 for color measurement is printed on paper periodically or at a timing specified by the operation unit 13. The in-line colorimetric unit 16 then measures the color of each color patch 30 on the color chart 31. Based on the measured colorimetric values, the image forming unit 12 adjusts the color of the image data.

[0033] In this embodiment, during such an operating period, the image processing unit 15 determines whether maintenance such as calibration of the inline colorimetric unit 16 is necessary, either periodically or at a timing specified by the operation unit 13. If maintenance is necessary, the image processing unit 15 operates the image forming apparatus using the multiple divided colorimetric data 41a of the external colorimetric unit 17. During this period, an operator removes the inline colorimetric unit 16 from the image forming apparatus 10 and performs maintenance.

[0034] The necessity of maintenance is determined by comparing the colorimetric data 41 acquired by the in-line colorimetric unit 16 with the plurality of divided colorimetric data 41 a acquired by the external colorimetric unit 17 . The colorimetric data 41 including the colorimetric values of all the color patches 30 of the color chart 31 can be obtained by the in-line colorimetric unit 16, for example, as follows. FIG. 7 is a flowchart showing the procedure for acquiring the colorimetric values of all color patches 30 from the colorimetric data 41 of the in-line colorimetric unit.

[0035] First, the DFE 11 generates image data of the color chart 31 based on a signal from the operation unit 13. Then, the image forming unit 12 outputs the chart printing paper 32 on which the color chart 31 is printed (step S11). Next, based on a purge processing signal from the control unit 14, the chart printing paper 32 is continuously passed from the image forming unit 12 to the in-line colorimetry unit 16. Then, the in-line colorimetry unit 16 measures the color of each color patch 30 of the color chart 31 on the chart printing paper 32 (step S12). Next, it is determined whether the number of chart printing papers 32 that have been color-measured by the in-line colorimetric unit 16 has reached a predetermined number (step S13). In step S13, if the number of chart printing papers 32 on which colorimetry has been performed does not reach the predetermined number (NO in step S13), the process returns to step S11.

[0036] The color measurement data 41 thus obtained appears as shown in FIG. 8B when viewed on the color chart 31 shown in FIG. 8A, for example. Since the color measurement head is moved in the opposite direction for each row to measure the colors, after the color measurement values from coordinates (1,11) to (1,4) of the color patch 30, the order of the rows is reversed, such as from coordinates (2,4) to coordinates (2,1) of the color patch 30. In the inline colorimetric unit 16, by measuring the colors of a large number of color patches 30 in this coordinate order, the color measurement values for each coordinate are obtained sequentially.

[0037] In step S13, if the number of chart printing papers 32 that have been measured reaches a predetermined number (YES in step S13), the image processing unit 15 ends the colorimetry of all chart printing papers 32. Then, the image processing unit 15 reads and discards the colorimetry values of the coordinates corresponding to the cutting area 36a between the color patterns 34 (step S14). For example, in the color chart 31 shown in FIG. 8A, the coordinates (3,1) to (3,4) are the colorless cutting area 36a, and the image processing unit 15 discards the colorimetry values of the coordinates (3,1) to (3,4) as shown in FIG. 8B.

[0038] Then, after discarding the colorimetric values of the colorless cutting area 36a, the image processing unit 15 rearranges the colorimetric data 41 with the coordinates and colorimetric values corresponding to each other (step S16), and stores the colorimetric data 41 in a memory unit not shown (step S16). For example, in a state where the coordinates (3,1) to (3,4) are discarded as shown in Fig. 8C, the image processing unit 15 may arrange the colorimetric values in the order of the colorimetric values. Alternatively, the image processing unit 15 may arrange the colorimetric values in the order of the coordinates as shown in Fig. 11B.

[0039] The external colorimetric unit 17 can obtain the colorimetric values of all the color patches 30 of the color chart 31 from the plurality of divided colorimetric data 41a, for example, as follows. FIG. 9 is a flowchart showing the procedure for acquiring the colorimetric values of all the color patches 30 from the divided colorimetric data 41a of the external colorimetric unit.

[0040] First, based on a signal from the operation unit 13, the DFE 11 generates image data for the color chart 31, and the image forming unit 12 outputs the chart printing paper 32 on which the color chart 31 is printed (step S21). The chart printing paper 32 is discharged to the paper discharge unit 19. Next, the image processing unit 15 determines whether the number of chart printing papers 32 on which colorimetry has been performed has reached a predetermined number (step S22). In step S22, if the predetermined number has not been reached (NO in step S22), the process returns to step S21, and chart printing sheets 32 are repeatedly printed and output until the predetermined number is reached.

[0041] If the predetermined number of sheets has been reached in step S22 (YES in step S22), the operator cuts the chart printing paper 32 along the cutting lines 36b of the cutting marks 36 on the printed chart printing paper 32 (step S23). The cutting in step S23 produces a plurality of pattern-printed sheets 35 on which the color patterns 34 are printed. Each pattern-printed sheet 35 has a color pattern 34 printed thereon, which is a chart having the same arrangement as the color chart 31 and which is divided into a plurality of pieces.

[0042] Next, the plurality of pattern-printed papers 35 are passed through the external colorimetric unit 17, and the external colorimetric unit 17 measures the color of each color patch 30 of the color pattern on each pattern-printed paper 35 (step S24). As a result, a plurality of divided colorimetric data 41a are obtained. Next, the external colorimetric unit 17 determines whether or not the number of measured pattern-printed sheets 35 has reached a predetermined number (step S25). If it is determined in step S25 that the number of measured pattern-printed sheets 35 has not reached the predetermined number (NO in step S25), the process returns to step S24, and repeated pattern-printed sheets 35 are produced and measured by the external colorimetric unit 17.

[0043] If it is determined in step S25 that the number of pattern-printed sheets 35 on which colorimetry has been performed has reached the predetermined number (YES in step S25), the external colorimetric unit 17 obtains the colorimetric values of the many color patches 30 in each color pattern 34 in the order of colorimetry.

[0044] Then, the external colorimetric unit 17 transfers the plurality of divided colorimetric data 41a acquired by colorimetric measurement as a colorimetric file to the image processing unit 15 using a transfer means (step S26). Here, the transfer means may be, for example, a device that connects a recording medium on which the colorimetric file is recorded to a transfer port of the operation unit 13 or the image processing unit 15. Alternatively, the transfer means may be a LAN or a transfer line that connects the external colorimetric unit 17 and the operation unit 13 or the image processing unit 15 by wire or wirelessly.

[0045] The image processing unit 15, to which the colorimetry file has been transferred, analyzes the colorimetry file (step S27). The image processing unit 15 reads and discards the colorimetry values of the coordinates corresponding to the cutting area 36a between the color patterns 34 in the color chart 31 before cutting (step S28).

[0046] In analyzing the colorimetry file, the image processing unit 15 associates the colorimetry values of each color chart 31 in the two color patterns 34 with coordinates in the color chart 31 before division. When the external colorimetric unit 17 measured the colors of each pattern-printed paper 35, the paper transport direction D2 was perpendicular to the paper transport direction D1 of the chart-printed paper 32. Therefore, the coordinates of each colorimetric value in the divided colorimetric data 41a of each color pattern 34 are swapped between rows and columns in the coordinates of the color chart 31. Furthermore, the order of one of the rows and columns is reversed. Therefore, the order of color measurement values in each color pattern 34 changes in a complex and regular manner from the arrangement of the color chart 31 before division.

[0047] For example, the color pattern 34 shown in Figures 10A and 10B is obtained by dividing the color chart 31 shown in Figure 8A. Each divided colorimetric data 41a is as shown in Figures 10C and 10D. Rows 1, 2, 4, and 5 in color chart 31 in Fig. 8A correspond to columns 1 and 2 in Fig. 10A and columns 4 and 5 in Fig. 10B. Also, columns 1, 2, 3, and 4 in color chart 31 in Fig. 8A correspond to rows 4, 3, 2, and 1 in Figs. 10A and 10B.

[0048] 10A and 10B by moving the color measurement head in the opposite direction for each row. Therefore, after the color measurement values of coordinates (1,4) and (2,4), the order is reversed to coordinates (2,3) and (1,3). Similarly, after the color measurement values of coordinates (4,4) and (5,4), the order is reversed to coordinates (5,3) and (4,3).

[0049] As a result, the colorimetric values recorded in the colorimetric data segments 41a in the order of color measurement are shown in the coordinates of the original color chart 31 as shown in FIGS. 10C and 10D, respectively. Therefore, the image processing unit 15 associates the colorimetric values of each divided colorimetric data 41a in the colorimetric order with the coordinates on the color chart 31 before division, and combines and rearranges the plurality of divided colorimetric data 41a (step S29).

[0050] When combining and rearranging the divided colorimetric data 41a, the image processing unit 15 can arrange the colorimetric values in various orders. For example, as shown in FIG. 8C, the image processing unit 15 may arrange the colorimetric values in the same order as the colorimetric order of the color chart 31 before division. Alternatively, the image processing unit 15 may simply concatenate two divided colorimetric data 41a as shown in FIG. 11A. Furthermore, the image processing unit 15 may arrange the colorimetric values in the coordinate order of the color chart 31 as shown in FIG. 11B.

[0051] The image processing unit 15 can also use the colorimetric values of some of the color patches 30 included in the divided colorimetric data 41a of each color pattern 34 to estimate the positions on the color chart 31 and perform synthesis. For example, the color chart 31 shown in Figure 12A is divided into two color patterns 34 shown in Figure 12B and Figure 12C. This color chart 31 is made up of color patches 30 of all different colors.

[0052] Therefore, the external colorimetric unit 17 can estimate the position on the color chart 31 shown in FIG. 12A using the colorimetric values of part of each color pattern 34 shown in FIGS. 12B and 12C. The external colorimetric unit 17 then combines the divided colorimetric data 41a together so that the multiple color patterns 34 are located at the estimated positions. This allows the external colorimetric unit 17 to synthesize colorimetric data 41 corresponding to all color patches of the color chart 31.

[0053] Thereafter, the combined and rearranged colorimetric data 41 is saved (step S30), which allows the image processing unit 15 to acquire the colorimetric values of all the color patches 30 on the color chart 31.

[0054] Next, the inline colorimetric unit 16 compares the acquired colorimetric data 41 with the colorimetric data 41 acquired and combined by the external colorimetric unit 17 to determine whether maintenance is required. The inline colorimetric unit 16 makes this determination by comparing the colorimetric values of the same coordinates on the color chart 31 for all color patches 30. That is, the inline colorimetric unit 16 determines whether the difference between the acquired colorimetric data 41 and the colorimetric data 41 acquired and combined by the external colorimetric unit 17 is within a predetermined reference range. That is, the inline colorimetric unit 16 determines that maintenance is required if the difference exceeds the predetermined reference range.

[0055] If it is determined that maintenance is necessary, for example, if the in-line colorimeter 16 has broken down or if the in-line colorimeter needs to be calibrated, the in-line colorimeter 16 is removed and maintenance is performed. During maintenance, as during normal operation, a color chart 31 for color measurement is printed on paper periodically or at a timing designated by the operation unit 13, and each color patch 30 is measured, and color adjustment is performed.

[0056] At this time, because the inline colorimetric unit 16 is removed, the external colorimetric unit 17 cuts the chart printing paper 32 to create pattern printing paper 35 and measures the color. As a result, in the same manner as described above, divided colorimetric data 41a of multiple color patterns 34 obtained by dividing a chart with the same arrangement as the color chart 31 is obtained. The external colorimetric unit 17 obtains the colorimetric values of all color patches 30 of the color chart 31 by combining the multiple divided colorimetric data 41a. This allows the external colorimetric unit 17 to perform color adjustment based on colorimetric values obtained by synthesizing multiple color patterns 34, making it possible to perform maintenance on the inline colorimetric unit 16 while the image forming apparatus 10 is operating.

[0057] Next, the effects and advantages obtained by the image forming apparatus 10, the colorimetric unit maintenance method, and the colorimetric chart printing paper 32 of this embodiment will be described. First, in this embodiment, the image processing unit 15 can acquire the colorimetric values of all color patches 30 of the color chart 31 from the colorimetric data 41 of the inline colorimetric unit 16. The image processing unit 15 can also acquire the colorimetric values of all color patches 30 by combining the divided colorimetric data 41a of a color pattern 34 obtained by dividing a chart having the same arrangement as the color chart 31.

[0058] Therefore, the image processing unit 15 can compare the colorimetric values obtained using the color chart 31 with the colorimetric values obtained using the multiple color patterns 34. Furthermore, the image processing unit 15 can substitute the colorimetric values obtained by combining the multiple color patterns 34 for the colorimetric values obtained using the color chart 31.

[0059] Moreover, in either case, the image processing unit 15 can collectively acquire multiple colorimetric values using the colorimetric data 41 of the color chart 31 or the divided colorimetric data 41a of multiple color patterns 34. This eliminates the need for the operator to take the trouble of acquiring multiple colorimetric values individually. Furthermore, even if the number of color patches 30 is large, the image processing unit 15 can easily evaluate or substitute the inline colorimetric unit 16. As a result, even if the in-line colorimetric unit 16 is capable of measuring the color of a large color chart 31, the worker can easily perform maintenance on the in-line colorimetric unit 16.

[0060] In this embodiment, the chart printing paper 32 on which the color chart 31 is printed is large in size. That is, the chart printing paper 32 has a width exceeding 320 mm, which makes it impossible for a typical automatic paper-feeding colorimeter to pass through it. However, in this embodiment, the chart printing paper 32 is cut so that the width of each of the multiple chart printing papers 32 on which color patterns 34 are printed is 320 mm or less. Therefore, the external colorimeter 17 can easily measure the color of all the color patches 30 of the color chart 31 by dividing them and passing them through a typical automatic paper-feeding colorimeter.

[0061] In this embodiment, pattern-printed paper 35 on which color patterns 34 are printed is formed by cutting chart-printed paper 32 on which color chart 31 is printed. Therefore, in this embodiment, a plurality of color patterns 34 in which the common arrangement with color chart 31 is divided can be reliably and easily obtained.

[0062] In this embodiment, the chart print paper 32 is provided with cutting marks 36 that indicate the positions for cutting between the multiple color patterns 34. This allows the operator to easily create multiple pattern print papers with appropriate color patterns 34.

[0063] In this embodiment, the cutting marks 36 have colorless cutting regions 36a that are provided between the multiple color patterns 34 and have a width that is an integral multiple of the width of the color patches 30. Therefore, when measuring the multiple color patches 30 of the color chart 31, there is no need to perform control such as changing the amount of movement of the color measurement head between the color patterns 34. This simplifies the control during color measurement in the inline colorimetry unit 16.

[0064] In this embodiment, the image processing unit 15 measures the color of the cutting area 36a in the color chart 31 together with the multiple color patches 30 of the color pattern 34, and discards the colorimetric values of this cutting area 36a. Therefore, the image processing unit 15 can perform control so that the multiple color patches 30 of each color pattern 34 are continuously measured, regardless of whether they are in the cutting area 36a or not. Therefore, the image processing unit 15 can simplify the control during colorimetric measurement.

[0065] In this embodiment, multiple pattern-printed papers 35 are formed by cutting the chart printing paper 32 in a direction perpendicular to the paper transport direction D1 during color measurement of the chart printing paper 32. These multiple pattern-printed papers 35 are produced by cutting the chart printing paper 32 so that the length of the chart printing paper 32 along the paper transport direction D1 during color measurement is shorter than the length in the perpendicular direction. The paper transport direction D2 during color measurement of the pattern-printed paper 35 is perpendicular to the paper transport direction D1 during color measurement of the chart-printed paper 32.

[0066] Therefore, even if the color chart 31 is a wide chart printing paper 32, by dividing it into a plurality of pattern printing papers 35, it is possible to narrow the width during color measurement and perform color measurement. This allows the color chart 31 to be measured even if it is a wide color chart on the chart printing paper 32, using a colorimeter that cannot measure the width of the chart printing paper 32. For example, it is possible to measure the color of the color chart 31 using a general colorimeter.

[0067] In this embodiment, the paper transport direction D2 of the pattern-printed paper 35 after cutting is depicted on the chart-printed paper 32. This allows the worker to avoid mistakes in the paper transport direction D2 of the multiple pattern-printed papers 35, preventing paper-feeding errors.

[0068] In this embodiment, the image processing unit 15 can rearrange and combine the multiple colorimetric values in the divided colorimetric data 41a of the multiple color patterns 34. Therefore, when rearranging the colorimetric values, the image processing unit 15 can rearrange the multiple colorimetric values in the order of the multiple color patches 30 on the color chart 31. Therefore, the color measurement values of each color patch 30 on the color chart 31 can be easily grasped, and the control of color adjustment and tone adjustment can be simplified.

[0069] In this embodiment, the shapes of the color patches 30 are the same across the color patterns 34. Therefore, when measuring colors using the color measurement head, the inline colorimeter 16 does not need to change settings for each of the color patterns 34, and color measurement accuracy can be made uniform. This simplifies the control and operation of the colorimeter and improves the ease of use of the image forming apparatus.

[0070] In this embodiment, the number of horizontal and vertical arrangements of color patches 30 in a color pattern 34 is the same across multiple color patterns 34. Therefore, when measuring colors using the color measurement head, the external colorimeter 17 does not need to change settings for each color pattern 34, and color measurement accuracy can be made uniform. This simplifies the control and operation of the colorimeter and improves the ease of use of the image forming apparatus.

[0071] In this embodiment, the image processing unit 15 estimates the arrangement of a color pattern 34 on the color chart 31 based on the colorimetric values of some of the color patches 30 in the color pattern 34. Based on the estimated arrangement, the image processing unit 15 also combines the divided colorimetric data 41a of that color pattern 34 with the divided colorimetric data 41a of other color patterns 34. Furthermore, by making the estimation based on the colorimetric values of multiple color patches 30, the influence of noise and the like is reduced.

[0072] Therefore, the image processing unit 15 can easily perform processing to combine the divided colorimetric data 41a obtained from the plurality of color patterns 34, and therefore the structure for data processing can be simplified. Furthermore, the image processing unit 15 does not require special processing, such as determining the order of colorimetry or specifying the position, when measuring each color pattern 34 or synthesizing multiple divided colorimetry data 41a, thereby improving the ease of use of the image forming device.

[0073] In this embodiment, the colorimetric values of the multiple color patches 30 obtained from the colorimetric data 41 of the color chart 31 are compared with the colorimetric values of the multiple color patches 30 obtained by combining the divided colorimetric data 41a of the multiple color patterns 34. Then, the image processing unit 15 determines whether maintenance such as calibration of the colorimetric head of the inline colorimeter is necessary based on the comparison result.

[0074] Therefore, the image processing unit 15 can easily compare differences between the color patches 30, reducing the effort required for control and operation to determine whether calibration is necessary, and can detect differences even if they occur in some colors. As a result, the image forming apparatus 10 can properly maintain the in-line colorimeter for a long period of time.

[0075] In this embodiment, the colors of a plurality of color patterns 34 are measured using an external colorimeter 17 that is separate from the inline colorimeter 16. Here, the color patterns 34 are formed by dividing the color chart 31, so the width of the pattern-printed paper 35 is narrower than the chart-printed paper 32. Therefore, an external colorimeter with a maximum paper feed width narrower than that of the inline colorimeter 16 can be used. This improves the ease of use of the image forming apparatus.

[0076] The above-described embodiment can be modified as appropriate within the scope of the claims of the present invention. For example, in the above embodiment, an example has been described in which each color pattern 34 on the multiple pattern-printed sheets 35 is measured by the external colorimetry unit 17, but this is not particularly limited. For example, the pattern-printed sheets 35 may be supplied separately to the inline colorimetry unit 16, discontinuously from the image forming unit 12, and measured. The image processing unit 15 may acquire the colorimetry values of all the color patches 30 on the color chart 31 by combining the divided colorimetry data 41a of the multiple color patterns 34 obtained in this way.

[0077] In the above-described embodiment, an example has been described in which the image processing unit 15 acquires the colorimetric values of all the color patches 30 of the color chart 31, but this is not particularly limited. The present invention is also applicable to cases in which the image processing unit 15 acquires the colorimetric values of some of the color patches 30 of the color chart 31 to perform color adjustment. Furthermore, in the above embodiment, an example was described in which the color pattern 34 on the pattern-printed paper 35 was measured by the external colorimetric unit 17, but the pattern-printed paper 35 may also be measured in the in-line colorimetric unit 16.

[0078] In addition, in the above-described embodiment, the color pattern 34 obtained by dividing a chart having the same arrangement as the color chart 31 is exemplified by dividing the color chart 31 itself, which is measured by the inline colorimetry unit 16, but this is not particularly limited. The chart having the same arrangement as the color chart 31 may be, for example, a chart formed separately from the color chart 31 whose colors are measured by the inline colorimetric unit 16. Also, the chart having the same arrangement as the color chart 31 may be a chart on which a plurality of color patterns 34 are printed separately. Furthermore, in the above-described embodiment, it is sufficient that the numerous color patches 30 are arranged in the same order as the color chart 31, so that charts with different shapes and sizes of the color patches 30 can also be used as the color pattern 34.

[0079] For example, a chart in which rectangular color patches 30 are arranged adjacent to one another as shown in Fig. 13A can be used as the color chart 31 to be measured by the inline colorimetric unit 16. At the same time, a chart in which color patches 30 smaller than those in Fig. 13A are arranged as shown in Fig. 13B can be used as the color chart 31 for creating a plurality of color patterns 34 to be measured by the external colorimetric unit 17. Furthermore, the color chart 31 or color pattern 34 may be printed on only a portion of the paper, such as on chart-printed paper 32 or pattern-printed paper 35 shown in Fig. 14. In this case, by ensuring that the color chart 31 or color pattern 34 is always printed in the same position, it is possible to prevent the effects of unevenness due to placement.

[0080] In the above embodiment, when it is determined that maintenance is necessary, color adjustment is performed using the colorimetric values of the color patch 30 obtained by combining the multiple pieces of divided colorimetric data 41a, but this is not particularly limited. It is also possible to perform color adjustment using colorimetric data obtained by combining the multiple pieces of divided colorimetric data 41a by the external colorimetric unit 17, without obtaining colorimetric data by the inline colorimetric unit 16. In the above, paper is used as the paper on which the color chart 31 and the color pattern 34 are printed, but other recording media such as film may also be used. [Explanation of symbols]

[0081] 10...image forming apparatus, 11...DFE, 12...image forming unit, 13...operation unit, 14...control unit, 15...image processing unit, 15a...comparison unit, 16...inline colorimetry unit, 17...external colorimetry unit, 18...paper feed unit, 19...paper discharge unit, 21...main cylinder, 22...head unit, 23...UV irradiation unit, 24...inline sensor, 25...print engine, 30...color patch, 31...color chart, 32...chart printed paper, 33...margin, 34...color pattern, 35...pattern printed paper, 36...cutting mark, 36a...cutting area, 36b...cutting line, 41...colorimetry data, 41a...divided colorimetry data

Claims

1. an image forming unit that prints a color chart on paper; an in-line color measurement unit that measures the color of a plurality of color patches formed on the color chart; an image processing unit that performs color adjustment based on colorimetric values of a plurality of color patches formed on the color chart, The image processing unit synthesizes a plurality of divided colorimetric data obtained by measuring a plurality of color patterns obtained by dividing a chart in which color patches are arranged in common with the color chart, and obtains colorimetric values of the plurality of color patches formed on the color chart from the synthesized plurality of divided colorimetric data.

2. The width of the chart printing paper on which the color chart is printed exceeds 320 mm, 2. The image forming apparatus according to claim 1, wherein the width of each of the plurality of pattern-printed papers on which the color patterns are printed is 320 mm or less.

3. 2. The image forming apparatus according to claim 1, wherein the pattern-printed paper on which the color pattern is printed is formed by cutting a chart-printed paper on which the color chart is printed.

4. 4. The image forming apparatus according to claim 3, wherein the chart printing paper is provided with cutting marks that indicate positions for cutting between the plurality of color patterns.

5. 5. The image forming apparatus according to claim 4, wherein the cutting marks have colorless cutting areas each having a width that is an integral multiple of the width of the color patch and are provided between the plurality of color patterns.

6. The image forming apparatus according to claim 5 , wherein the color measurement unit measures the color of the cutting area in the color chart together with the plurality of color patches of the plurality of color patterns, and discards the color measurement values of the cutting area.

7. the plurality of pattern-printed sheets are formed by cutting the chart-printed sheets in a direction perpendicular to a paper transport direction during color measurement of the chart-printed sheets, and such that the length along the paper transport direction is shorter than the length in the direction perpendicular to the paper transport direction; 4. The image forming apparatus according to claim 3, wherein a paper transport direction during color measurement of the pattern-printed paper is perpendicular to a paper transport direction during color measurement of the chart-printed paper.

8. 4. The image forming apparatus according to claim 3, wherein the chart printed paper has a mark indicating a paper transport direction of the pattern printed paper after cutting.

9. The image forming apparatus according to claim 1 , wherein the image processing unit is capable of combining the colorimetric values in the divided colorimetric data of the color patterns by rearranging them in the order of the color patches in the color chart.

10. The image forming apparatus according to claim 1 , wherein the shapes of the color patches are the same among the plurality of color patterns.

11. 2. The image forming apparatus according to claim 1, wherein the number of rows and columns of the color patches in the color patterns is the same among the plurality of color patterns.

12. 2. The image forming apparatus according to claim 1, wherein the image processing unit is capable of estimating the arrangement of the color patterns in the color chart based on the colorimetric values of some of the color patches in the color patterns, and synthesizing the divided colorimetric data of the plurality of color patterns based on the estimated arrangement.

13. 2. The image forming apparatus according to claim 1, wherein the image processing unit includes a comparison unit that compares the colorimetric data with the combined plurality of divided colorimetric data.

14. The image forming apparatus according to claim 13 , wherein the image processing unit is capable of determining whether maintenance of the in-line color measurement unit is required based on the comparison result of the comparison unit.

15. The image forming apparatus according to claim 1 , further comprising an external colorimetric unit separate from the in-line colorimetric unit, wherein the colorimetric units measure the colors of the plurality of color patterns.

16. Print the color chart on paper A plurality of color patches formed on the color chart are measured by an in-line colorimetric unit; a maintenance method for a colorimetric unit of an image forming apparatus that performs color adjustment based on colorimetric values of a plurality of color patches formed on the color chart, a colorimetric value of the plurality of color patches is obtained by combining divided colorimetric data obtained by measuring the color of a plurality of color patterns obtained by dividing a chart having the same arrangement as the color chart; A maintenance method for a colorimetric unit, the method comprising: comparing colorimetric values obtained using the color chart with colorimetric values obtained using the plurality of color patterns to determine whether maintenance of the in-line colorimetric unit is necessary.

17. Print the color chart on paper A plurality of color patches formed on the color chart are measured by an in-line colorimetric unit; a maintenance method for a colorimetric unit of an image forming apparatus that performs color adjustment based on colorimetric values of a plurality of color patches formed on the color chart, A maintenance method for a colorimetric unit, which combines divided colorimetric data obtained by measuring a plurality of color patterns obtained by dividing a chart having the same arrangement as the color chart, obtains colorimetric values of the plurality of color patches, performs color adjustment based on the colorimetric values, and maintains the in-line colorimetric unit.

18. a color measurement chart printing paper on which a color chart having a plurality of color patches is printed; the color chart is provided with a plurality of separable color patterns each having the plurality of color patches; The color measurement chart printed paper can be cut between the plurality of color patterns to form a plurality of pattern-printed papers on which the color patterns are printed.

Images