JP2007205722A - Measuring system and measuring method for measuring reflection characteristic - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure a reflection characteristic of each measuring point by determining measuring points properly, even for a printing medium on which a monochromatic image having a uniform density is printed. <P>SOLUTION: This measuring system includes, for example, a setting means, a designation means, a determination means and a movement measuring means. The setting means sets two or more reference points in a monochromatic printing domain provided on the printing medium. The designation means designates a measuring condition for determining a plurality of measuring domains in the printing domain. The determination means determines the coordinate of each measuring point in the plurality of measuring domains, based on the reference points and the measuring condition. The measuring means measures the reflection characteristic of each measuring point by moving successively according to the determined coordinate of each measuring point. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a technique for measuring reflection characteristics of a print medium.

  Measuring the reflection characteristics of the print medium, for example, spectral reflectance (so-called colorimetry) is very important in evaluating the quality of each print medium. In order to measure the reflection characteristics of the print medium, it is desirable that the coordinates of the measurement area in the print medium can be determined as easily as possible.

According to Patent Document 1, a method is proposed in which, on a print medium on which the same pattern is regularly printed, the coordinates of one pattern are determined based on the regularity of the pattern just by inputting the coordinates of one pattern. Has been.
JP-A-8-261829

  By the way, when evaluating printing unevenness or the like, in general, an image having a single color and a uniform density is often printed on a printing medium. In such a print medium, there is no regular pattern that can be identified. Therefore, the technique described in Patent Document 1 has a drawback that the measurement point cannot be automatically determined.

  If a regular mark is printed on the print medium, the measurement area may be detected based on the mark. However, in an electrophotographic printing apparatus, the formation of this mark may cause toner scattering or a close-up phenomenon, which is not preferable in evaluating the spectral reflectance.

  Therefore, an object of the present invention is to solve at least one of such problems and other problems. Other issues can be understood throughout the specification.

  The present invention is implemented, for example, in a measurement system that measures the reflection characteristics of a print medium. The measurement system includes, for example, setting means, designation means, determination means, and movement measurement means. The setting means sets two or more reference points in a single color print area provided on the print medium. The designation means designates measurement conditions for determining a plurality of measurement areas in the print area. The determining means determines the coordinates of each measurement point in the plurality of measurement regions based on the reference point and the measurement conditions. The measurement means sequentially moves according to the determined coordinates of each measurement point, and measures the reflection characteristics of each measurement point.

  According to the present invention, there is an advantage that even a print medium on which an image having a single color and uniform density is printed can suitably determine measurement points and measure the reflection characteristics of each measurement point.

  An embodiment of the present invention is shown below. Of course, the individual embodiments described below will be helpful in understanding various concepts such as the superordinate concept, intermediate concept and subordinate concept of the present invention. Further, the technical scope of the present invention is determined by the scope of the claims, and is not limited by the following individual embodiments.

<Outline of measurement and evaluation system>
FIG. 1 is a diagram illustrating an example of a system for performing measurement and evaluation according to the embodiment. In this system, for example, color unevenness can be evaluated by measuring reflection characteristics of an image printed on a print medium. Examples of the reflection characteristics include spectral reflectance, optical density, chromaticity, and glossiness. Here, spectral reflectance will be described as an example.

  This system includes a measuring apparatus 100 that measures spectral reflectance and a personal computer (PC) 150 that controls the measuring apparatus 100. The measuring apparatus 100 is, for example, an automatic colorimeter. The PC 150 is an example of an information processing apparatus that uses the measurement apparatus 100.

  The measurement apparatus 100 includes a measurement table 101, rails 102 and 103 provided on the measurement table, a movable unit 104 that moves on the rail, and a spectrophotometer 105 that is attached to the movable unit. A print medium 106 to be measured is placed on the measurement table 101. The measurement table 101 is sometimes called an XY table or an XY stage.

  The movable unit 104 moves in the horizontal direction (X direction) in the figure. The spectrophotometer 105 is moved in the vertical direction (Y direction) by the movable unit 104. That is, the spectrophotometer 105 can freely move on the XY coordinates. The movable unit 104 moves the spectrophotometer 105 to designated coordinates from the PC 150. The spectrophotometer 105 performs measurement at the coordinates.

  FIG. 2 is a block diagram illustrating an example of a control unit of the measurement apparatus according to the embodiment. The CPU 201 is a control unit that comprehensively controls each unit of the measuring apparatus 100 based on a computer program. The ROM 202 is a non-volatile storage unit that stores a computer program such as firmware. The RAM 203 is a volatile storage unit that functions as a work area. The display device 205 is a display unit for displaying various information to the user. The operation unit 206 is an input unit including, for example, up / down / left / right movement keys, a determination key, and a cancel key. Through the operation unit 206, the user can move the spectrophotometer 105 by manual operation.

  The communication interface 207 is a communication unit for communicating with the PC 150 such as a USB interface. Data measured by the spectrophotometer 105 is transferred to the PC 105 via the communication interface 207. The A / D converter 210 is a unit that converts an analog signal output from the spectrophotometer 105 into a digital signal. The drive control unit 211 controls the drive motor 212. The drive motor 212 is a motor for moving the movable unit 104 in the X-axis direction, a motor for moving the spectrophotometer 105 attached to the movable unit 104 in the Y-axis direction, or the like.

  FIG. 3 is a block diagram illustrating an example of a PC according to the embodiment. The CPU 301 is a control unit that comprehensively controls each unit of the PC 150 based on a computer program. The ROM 302 is a non-volatile storage unit that stores a computer program such as firmware. The RAM 303 is a volatile storage unit that functions as a work area. A hard disk drive (HDD) 304 is a large-capacity storage unit. The HDD 304 stores measurement data received from the measurement apparatus 100, measurement data evaluation programs, and the like.

  The display device 305 is a display unit for displaying various information to the user. The operation unit 306 is an input unit such as a pointing device or a keyboard. The communication interface 307 is a communication unit for communicating with the measurement apparatus 100 such as a USB interface.

<Outline of measurement process>
FIG. 4 is a flowchart illustrating an example of a measurement process according to the embodiment. This flowchart corresponds to the main routine of the computer program for measurement. The computer program for measurement may be integrated with an evaluation computer program for evaluating measurement data.

  In step S <b> 401, the CPU 301 of the PC 150 displays a measurement condition designation screen on the display device 305 and sets measurement conditions based on information input from the operation unit 306.

  FIG. 5 is a diagram illustrating an example of a measurement condition input screen according to the embodiment. The input screen 500 is an example of a screen for inputting measurement conditions necessary for determining a measurement region (mainly coordinates of measurement points). The input screen 500 includes a radio button 501 for designating a method for determining a measurement point, a text box 502 for designating parameters such as the number of rows L and the number of columns M, and a decision button for confirming input contents. 503 etc. are arranged. For example, when the determination method 1 is designated, the print area is divided into N = L × M measurement areas.

  In step S402, the CPU 301 executes reference point setting. For example, the CPU 301 instructs the measurement apparatus 100 to set a reference point via the communication interface 307. When receiving an instruction from the PC 150, the CPU 201 of the measuring apparatus 100 displays a message on the display device 205 so as to set a reference point.

  FIG. 6 is a diagram for explaining reference point setting processing according to the embodiment. In this example, there is a print area 600 where an image is printed on the print medium 106. Here, the printing area is rectangular. Note that the print area is not necessarily rectangular.

  There are four vertices in the rectangle. In the present embodiment, the four vertexes are a first reference point 601, a second reference point 602, a third reference point 603, and a fourth reference point 604. As is apparent from the figure, the first reference point 601 and the fourth reference point 604 are located on a diagonal line. Further, the second reference point 602 and the third reference point 603 are located on the diagonal line.

  FIG. 7 is a flowchart illustrating an example of a reference point setting process according to the embodiment. In step S <b> 701, the CPU 201 of the measurement apparatus 100 determines whether a movement instruction is input from the operation unit 206. If it has been input, the process proceeds to step S702. If it has not been input, the process proceeds to step S703.

  In step S <b> 702, the CPU 201 moves the spectrophotometer 105 in response to depression of the up / down / left / right key of the operation unit 206. The user moves the spectrophotometer 105 to at least two vertices by pressing the up / down / left / right keys, and aligns the target cross mark provided on the spectrophotometer 105 with the vertices.

  In step S703, the CPU 201 determines whether or not the enter key has been pressed. If it has been pressed, the process proceeds to step S704. If it has not been pressed, the process returns to step S701.

  In step S704, the CPU 201 acquires the coordinates (x, y) at that time as reference point data. In step S <b> 705, the CPU 201 determines whether acquisition of data relating to two or more reference points has been completed. If completed, the process advances to step S705, and the CPU 201 transfers the acquired coordinate data of the reference point to the PC 150. On the other hand, if not completed, the process returns to step S701. In this way, the coordinate data of the reference point is set.

  Here, in order to acquire the coordinate data of the reference point, the spectrophotometer 105 is manually moved to the apex, but the spectrophotometer 105 may be automatically moved. For example, by providing an image sensor such as a CCD in the spectrophotometer 105, the CPU 201 can recognize the vertex from the image data of the captured print area. Further, the CPU 201 may acquire the coordinates of the vertexes that have been image-recognized based on the image data.

  Returning to the description of FIG. In step S403, the CPU 301 of the PC 150 determines the coordinates of each measurement point according to the measurement conditions and the coordinate data of the reference point. Here, three examples will be described.

<First determination method>
FIG. 8 is a diagram for explaining a method of determining the first measurement point according to the embodiment. In this example, the print area 600 is divided into blocks of L rows × M columns. Each block corresponds to the above-described measurement region. Note that the measurement region actually measured by the spectrophotometer 105 is a region determined by a so-called observation viewing angle or the like. The measurement point is, for example, the center position of this region. Note that these parameters such as the number of rows L and the number of columns M are specified via the operation unit 306 in step S401.

  FIG. 9 is a flowchart illustrating an example of a measurement point determination method according to the embodiment. This flowchart is a subroutine of step S403 described above. In addition, in FIG. 9 and another figure, it cannot be overemphasized that the order of each step is interchangeable as long as it does not contradict.

  Further, two vertices on the diagonal line among the four vertices in the rectangular print area are set as two reference points. For example, the first reference point 601 and the fourth reference point 604 form a reference point pair. The second reference point 602 and the third reference point 603 form a reference point pair.

  In step S <b> 901, the CPU 301 of the PC 150 reads the coordinate data for the two reference points from the RAM 303 and determines the width (lateral length) Lw of the print area. For example, if the coordinates of the first reference point are (X1, Y1) and the coordinates of the second reference point are (X4, Y4), the width Lw of the print area is calculated from the following equation.

Lw = | X4-X1 |
In step S <b> 902, the CPU 301 reads the coordinate data for the two reference points from the RAM 303 and determines the height (length in the vertical direction) Lh of the print area. For example, if the coordinates of the first reference point are (X1, Y1) and the coordinates of the fourth reference point are (X4, Y4), the height Lh of the print area is calculated from the following equation.

Lh = | Y4-Y1 |
In step S903, the CPU 301 determines the width Tw per block obtained when the print area is divided into L rows × M columns based on the width Lw of the print area. For example, Tw is calculated from the following equation.

Tw = Lw / M
In step S904, the CPU 301 determines the height Th per block obtained when the print area is divided into L rows × M columns based on the height Lh of the print area. For example, Th is calculated from the following equation.

Th = Lh / L
In step S905, the CPU 301 determines the X of the measurement point in the P (1 ≦ P ≦ L) row Q (1 ≦ Q ≦ M) column based on the x coordinate X1 of the reference point 1 and the width Tw per block. The coordinates MEx are determined. MEx is calculated from the following equation, for example.

MEx = X1 + Tw × (Q−1) + Tw / 2
= X1 + Tw x (Q-0.5)
In step S906, the CPU 301 determines the y coordinate MEy of the measurement point in the Pth row and the Qth column based on the y coordinate Y1 of the reference point 1 and the height Th per block. MEy is calculated from the following equation, for example.

MEy = Y1 + Th × (P−1) + Th / 2
= Y1 + Th x (P-0.5)
In the example described above, the coordinates of each measurement point are determined using the first reference point 601 and the fourth reference point 604. Of course, the coordinates of each measurement point may be determined using the second reference point 602 and the third reference point 603.

  For example, if the coordinates of the second reference point are (X2, Y2) and the coordinates of the third reference point are (X3, Y3), the width Lw of the print area and the height Lh of the print area are calculated from the following equations. The

Lw = | X2-X3 |
Lh = | Y3-Y2 |
The measurement point (MEx, MEy) in the Pth row and the Qth column is calculated from the following equation, for example.

MEx = X3 + (Lw / M) × (Q-1) + (Lw / M) / 2
= X3 + Tw x (Q-0.5)
MEy = Y2 + (Lh / L) × (P-1) + (Lh / L) / 2
= Y2 + Th x (P-0.5)
As described above, according to the present embodiment, the coordinates of each measurement point can be suitably determined based on the coordinates of two reference points that can determine the print area.

<Second determination method>
FIG. 10 is a diagram for explaining a method of determining the second measurement point according to the embodiment. In this example, first, the print area 600 is divided into L rows. Further, Mi is the distance between two adjacent measurement points (measurement interval). Also, the shortest distance from one side (left side) of the print area along the direction (y-axis direction in the figure) perpendicular to the direction in which the row extends (x-axis direction in the figure) to the first measurement point Let the distance be Md. These parameters are specified via the operation unit 306 in step S401.

  FIG. 11 is a flowchart illustrating an example of a measurement point determination method according to the embodiment. This flowchart is a subroutine of step S403 described above. It should be noted that parts already described are denoted by the same reference numerals, and description thereof is omitted. Again, the first reference point 601 and the fourth reference point 604 are taken as a reference point pair.

  After executing Steps S901, S902, and S904 described above, the process proceeds to Step S1104. In step S1104, the CPU 301 determines the x coordinate MEx of the measurement point in the P-th row using the x coordinate X4 of the fourth reference point, the shortest distance Md, and the measurement interval Mi. For example, MEx is calculated by the following formula.

MEx = (X4−Md) + Mi × a
Here, a is a positive integer in a range where MEx is not smaller than X1 and is not larger than X4. Note that the y-coordinate MEy of each measurement point is calculated in step S906 as described above.

  In the example described above, the coordinates of each measurement point are determined using the first reference point 601 and the fourth reference point 604. Of course, the coordinates of each measurement point may be determined using the second reference point 602 and the third reference point 603. In this case, for example, the coordinates are determined by the following formula.

MEx = (X2−Md) + Mi × a
MEy = Y2 + (Lh / L) × (P−1) + (Lh / L) / 2
= Y2 + Th x (P-0.5)
As described above, according to the second determination method, the coordinates of each measurement point can be determined by the measurement interval Mi. Since the measurement interval Mi corresponds to a measurement cycle, the second determination method may be convenient when performing periodic color evaluation.

<Third determination method>
The third determination method is a modification of the first determination method. In the first determination method, the entire print area having the width Lw and the height Lh is divided into L rows × M columns. In the third determination method, an area having a width of Mw is further divided into M columns. Note that Mw is a width that is equal to or smaller than the width Lw of each row obtained by being divided into L rows.

  FIG. 12 is a diagram for explaining a method of determining the third measurement point according to the embodiment. As can be seen from the figure, the entire print area is divided into L lines. That is, the total number of rows is L. Here, of the horizontal length (width) Lw of each row, a partial region having a length of Mw is divided into M columns. As a result, the total number of columns in the area is M. Here, Mw is referred to as a measurement width. These parameters are specified via the operation unit 306 in step S401.

  FIG. 13 is a flowchart illustrating an example of a measurement point determination method according to the embodiment. This flowchart is a subroutine of step S403 described above. It should be noted that parts already described are denoted by the same reference numerals, and description thereof is omitted. Further, the first reference point 601 and the fourth reference point 604 are set as a reference point pair.

  If the print area height Th is determined in step S902, the process advances to step S1303. In step S1303, the CPU 301 determines a block width Tw ′ per block obtained when the measurement area having the measurement width Mw is divided so that the total number of columns is M. For example, the width Tw ′ of one block is calculated by the following equation.

Tw '= Mw / M
Next, in step S904, the height Th of the measurement region is calculated. Subsequently, in step S1305, the CPU 301 determines the x coordinate MEx of the measurement point in the P-th row based on the x coordinate X4 of the fourth reference point, the measurement width Mw, and the width Tw ′ of one block. For example, the x coordinate MEx is calculated by the following equation.

MEx = (X4−Mw) + Tw ′ / 2 + Tw ′ × b
= (X4−Mw) + Tw ′ × (b + 0.5)
At this time, b is an integer satisfying 0 ≦ b <M.

  Thereafter, in step S906, the y coordinate MEy of the measurement point is determined. Note that the coordinates of each measurement point may be determined using the second reference point 602 and the third reference point 603 also in the third determination method.

MEx = (X2−Mw) + Tw ′ × (b + 0.5)
MEy = Y2 + Th × (P−0.5)
As described above, according to the third method, the coordinates of each measurement point in a partial area having the measurement width Mw in the print area can be determined. Note that the measurement width Mw may be the measurement interval Mi described above. In this case, the measurement width Mw is a kind of measurement cycle. Therefore, if each measurement point determined by the third determination method is color-measured, it will be possible to evaluate color unevenness within one period.

<About measurement (colorimetry)>
FIG. 14 is a flowchart illustrating an example of a measurement process according to the embodiment. This flowchart corresponds to step S404 described above. The CPU 201 of the measuring apparatus 100 starts measurement in response to a measurement execution instruction from the PC 150.

  In step S1401, the CPU 201 of the measuring apparatus 100 executes calibration of the spectrophotometer 105. The calibration is executed, for example, by measuring the color of a white reference plate with the spectrophotometer 105.

  In step S1402, the CPU 201 moves the spectrophotometer 105 to the corresponding measurement point according to the coordinate data of each measurement point designated from the PC 150. Note that the coordinate data of each measurement point is transferred from the PC 150 to the measurement apparatus 100 in step S403, for example.

  In step S1403, the CPU 201 performs measurement using the spectrophotometer 105 that has reached a desired measurement point. The acquired measurement data is held in the RAM 203. In step S <b> 1404, the CPU 201 reads measurement data from the RAM 203 and transfers it to the PC 150. Note that the CPU 301 of the PC 150 stores the received measurement data in the RAM 303 or the HDD 304 together with the coordinate data of the corresponding measurement point.

  In step S1405, the CPU 201 determines whether measurement has been completed for all measurement points. If not completed, the process returns to step S1402, and the CPU 201 performs measurement for the next measurement point.

<Evaluation process>
FIG. 15 is a flowchart illustrating an example of the evaluation process according to the embodiment. In step S1501, the CPU 301 of the PC 150 functioning as a color evaluation apparatus reads measurement data from the RAM 303 or the like.

  In step S <b> 1502, the CPU 301 selects a measurement data set to be used as reference data among all the read measurement data in accordance with an instruction from the operation unit 306. The set of reference data is, for example, a group of measurement data in the rightmost position in the print area. This is only an example. For example, a set of reference data may be freely selected through the operation unit 306 and the display device 305.

  In step S1503, the CPU 301 calculates a color difference between the selected reference data set and all measurement data sets. Note that one set means, for example, each measurement data for the measurement points forming one line in the print area.

  In step S1504, the CPU 301 executes, for example, statistical processing for displaying a calculation result in a graph. Any statistical process may be employed as long as a user such as an evaluator can appropriately evaluate the color difference. In step S1505, the CPU 301 displays the result obtained by the statistical processing on the display device 305 as a graph. Any display format may be adopted as the display format of the statistical processing results as long as the evaluator can appropriately perform the evaluation.

  As described above, according to this embodiment, the CPU 301 determines the measurement conditions for determining a plurality of measurement areas for a single color print area provided on the print medium, and two or more reference points in the print area. Based on the above, the coordinates of each measurement point in a plurality of measurement regions can be determined. Therefore, even if the same pattern is not regularly arranged, the coordinates of the measurement point can be determined by a relatively simple method. Further, it is not necessary to print a mark or a patch frame in order to determine the measurement point. In particular, a mark or the like is not preferable when evaluating color unevenness because the image quality may be deteriorated. Therefore, the invention according to this embodiment will be effective.

  The measurement apparatus 100 includes a measurement table 101 for placing a print medium, and a spectrophotometer 105 that measures spectral reflectance while moving above the table according to designated coordinates. By controlling such a measuring apparatus 100 from the PC 150, there is an advantage that measurement data necessary for evaluating color unevenness can be acquired automatically.

  As described above, it is preferable that the two or more reference points include at least two vertices on the diagonal line among the four vertices in the rectangular print region. This is because if the print area is rectangular, the outline of the print area can be specified if the coordinates of the two vertices on the diagonal line are known.

  As described with respect to the first determination method, dividing the rectangular print region into L rows × M columns may be specified as the measurement condition. In this case, the CPU 301 can determine the coordinates of the center positions of the N measurement areas obtained when the rectangular print area is divided into L rows × M columns as the coordinates of the measurement points. It should be noted that by dividing the printing area into L lines, it is possible to evaluate periodic color unevenness in the main scanning direction of the printing apparatus. In addition, by dividing the printing area into M columns, periodic color unevenness in the sub-scanning direction of the printing apparatus can be evaluated.

  As described for the second determination method, the rectangular print area is divided into L lines, the interval Mi between the measurement points in each line, and the shortest distance Md from one side of the print area to the first measurement point are measured. It may be specified as a condition. In this case, the CPU 301 can determine the coordinates of each measurement point according to the total number L of rows, the measurement point interval Mi, and the shortest distance Md. In particular, depending on the parameter setting, the color unevenness of an arbitrary part in the print medium can be evaluated. For example, it will be possible to easily evaluate the color unevenness of a portion of the printing paper (such as the vicinity of the horizontal side in the printing direction or the central portion).

  Further, as described regarding the third determination method, the rectangular print region is divided into L rows, the measurement width Mw that is equal to or less than the full width of each row, and the region in the row that is the measurement width Mw is further divided into M columns. Dividing may be specified as a measurement condition. In this case, the CPU 301 can determine the coordinates of the center position of each measurement region as the coordinates of each measurement point according to the total number L of rows, the measurement width Mw, and the total number M of columns.

  In the second and third determination methods, the measurement interval Mi and the measurement width Mw may be set using the radius r of a circular part (transfer drum or the like) of the printing press. That is, the circumference of the circular part corresponds to one period in the printing area.

Mi = 2πr
Mw = 2πr
[Second Embodiment]
By the way, in the above-described embodiment, it is assumed that the print medium is accurately placed along the X axis and the Y axis. However, in reality, the print medium may be placed obliquely with respect to the X axis or the Y axis.

  FIG. 16 is a diagram illustrating a print medium placed obliquely with respect to the XY stage. For example, it is assumed that the PC 150 executes the method for recognizing the print region 600 based on the first reference point and the fourth reference point described above. In this case, the PC 150 erroneously recognizes the area 1601 as a print area. Therefore, in this embodiment, a method for determining a measurement point when the print medium 106 is placed obliquely will be described.

  Here, for example, at least three vertices out of four vertices in the rectangular print area are used as reference points. This is to detect the inclination of the print medium or print area. Specifically, the CPU 301 or the CPU 201 calculates the inclination of the print medium with respect to the XY stage based on the coordinates of two vertices that are not on the diagonal line among the three vertices. Further, the CPU 301 or the CPU 201 determines the coordinates of each measurement point in consideration of the calculated inclination.

  FIG. 17 is a flowchart illustrating an example of a method for determining a measurement point in consideration of the inclination of the print area according to the embodiment. Here, inclination correction is applied to the first determination method described above. Of course, inclination correction may be applied to the second determination method or the third determination method.

  Note that in step S <b> 402 described above, the CPU 301 acquires coordinate data of three reference points through the measuring apparatus 100. Here, the first reference point 601, the second reference point 602, and the third reference point 604 are used.

  In step S1701, the CPU 301 of the PC 150 reads the coordinate data for the three reference points from the RAM 303, and determines the width (lateral length) Lw of the print area. Lw is calculated by the following equation, for example.

  In step S <b> 1702, the CPU 301 reads coordinate data for three reference points from the RAM 303 and determines the height (vertical length) Lh of the print area. For example, the print area height Lh is calculated from the following equation.

  In step S 1703, the CPU 301 determines the inclination θ of the print medium 106 with respect to the X axis of the XY stage 101. For example, the inclination θ is calculated from the following equation.

tan <SUP> -1 </ SUP> θ = | Y2-Y1 | / | X2-X1 |
Thereafter, the above-described steps S903 to S906 are executed to calculate the measurement points (MEx, MEy) of P rows and Q columns.

  In step S <b> 1707, the CPU 301 determines the coordinates (MEx ′, MEy ′) of the measurement points whose inclination is corrected by rotating the coordinates (MEx, MEy) of the measurement points by θ around (X1, Y1). To do.

  As described above, according to the present embodiment, even when the print medium or the print area is placed obliquely, the reference points are at least three of the four vertices in the rectangular print area. It can measure suitably. More specifically, based on the coordinates of two vertices that are not on the diagonal line among the three reference points, the CPU 301 can calculate the inclination of the print medium or print area with respect to the table. Then, the CPU 301 can correct the calculated inclination and determine the coordinates of each measurement point.

It is a figure which shows an example of the system for performing the measurement and evaluation which concern on embodiment. It is a block diagram which shows an example of the control part of the measuring device which concerns on embodiment. It is a block diagram which shows an example of PC concerning embodiment. It is a flowchart which shows an example of the measurement process which concerns on embodiment. It is a figure which shows an example of the input screen of the measurement conditions which concern on embodiment. It is a figure for demonstrating the setting process of the reference point which concerns on embodiment. It is a flowchart which shows an example of the setting process of the reference point which concerns on embodiment. It is a figure for demonstrating the determination method of the 1st measurement point which concerns on embodiment. It is a flowchart which shows an example of the determination method of the measurement point which concerns on embodiment. It is a figure for demonstrating the determination method of the 2nd measurement point which concerns on embodiment. It is a flowchart which shows an example of the determination method of the measurement point which concerns on embodiment. It is a figure for demonstrating the determination method of the 3rd measurement point which concerns on embodiment. It is a flowchart which shows an example of the determination method of the measurement point which concerns on embodiment. It is a flowchart which shows an example of the measurement process which concerns on embodiment. It is a flowchart which shows an example of the evaluation process which concerns on embodiment. It is a figure which shows the printing medium mounted diagonally with respect to the XY stage. 6 is a flowchart illustrating an example of a method for determining a measurement point in consideration of the inclination of the print area according to the embodiment.

Claims (11)

A measurement method for measuring the reflection characteristics of a print medium,
A designation step for designating measurement conditions for determining a plurality of measurement areas in a single color print area provided on the print medium;
A setting step of setting coordinates of two or more reference points in the print region;
A determination step of determining coordinates of each measurement point in the plurality of measurement regions based on the coordinates of the reference point and the measurement conditions;
A measurement step of causing the measuring device to measure the reflection characteristic of each measurement point in accordance with the determined coordinates of each measurement point.   In the measuring step, the measuring device including a table for placing the print medium and a reflection characteristic measuring device that measures reflection characteristics while moving on the table according to specified coordinates is used. The measuring method according to claim 1.   The measurement method according to claim 2, wherein the two or more reference points include at least two vertices on a diagonal line among four vertices in the rectangular print area.   When it is specified as the measurement condition that the rectangular print area is divided into L rows × M columns, the determination step is obtained when the rectangular print area is divided into L rows × M columns. The measurement method according to claim 3, wherein coordinates of a center position of each of the N measurement areas are determined as coordinates of the measurement points.   As the measurement conditions, the rectangular print area is divided into L rows, the interval between measurement points in each row obtained by the division, and the direction along the direction orthogonal to the extending direction of the rows. When the shortest distance from one side of the print area to the first measurement point is specified, in the determination step, the coordinates of each measurement point are determined according to the total number L of the rows, the interval between the measurement points, and the shortest distance. The measuring method according to claim 2, wherein:   As the measurement conditions, the rectangular print region is divided into L rows, a measurement width that is equal to or less than the full width of each row obtained by the division, and a region in the row that becomes the measurement width is further divided into M columns. In the determining step, the coordinates of the center position of each measurement region obtained by the division are determined as the coordinates of each measurement point according to the total number L of the rows, the measurement width, and the total number M of the columns. The measuring method according to claim 2, wherein:   The measurement method according to claim 2, wherein the two or more reference points include at least three vertices among four vertices in the rectangular print area. An inclination calculation step of calculating an inclination of the print medium or the print area with respect to the table based on coordinates of two vertices that are not on a diagonal line among the three vertices;
The measurement method according to claim 7, wherein in the determination step, the calculated inclination is corrected to determine the coordinates of each measurement point.   The measurement method according to claim 1, wherein the reflection characteristic is at least one of spectral reflectance, optical density, chromaticity, and glossiness. A measurement system for measuring reflection characteristics of a print medium,
Designating means for designating measurement conditions for determining a plurality of measurement areas for a single color print area provided on the print medium;
Setting means for setting coordinates of two or more reference points in the print region;
Determining means for determining the coordinates of each measurement point in the plurality of measurement regions based on the coordinates of the reference point and the measurement conditions;
A measurement system comprising: moving measurement means for sequentially moving according to the determined coordinates of each measurement point and measuring the reflection characteristic of each measurement point. A computer program that, when run on a computer,
A designation step for designating measurement conditions for determining a plurality of measurement areas in a single color print area provided on the print medium;
A setting step of setting coordinates of two or more reference points in the print region;
A determination step of determining coordinates of each measurement point in the plurality of measurement regions based on the coordinates of the reference point and the measurement conditions;
And a measurement step of measuring the reflection characteristic of each measurement point in accordance with the determined coordinates of each measurement point.

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