Evaluation Method and Evaluation System for Soft Magnetic Material

Abstract

To provide an evaluation method of magnetic properties of a soft magnetic material used for electromagnets capable of evaluating variations in coercive force in particular before assembling products such as electronic lenses.SOLUTION: The evaluation method of a soft magnetic material includes the steps of: imaging the surface of the soft magnetic material with an imaging unit to acquire a crystal structure image of the soft magnetic material; evaluating the coercive force variation of the soft magnetic material by processing the crystal structure image of the acquired soft magnetic material using an information processing system; and displaying information about the coercive force variation of the evaluated soft magnetic material on the display terminal.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a method and a system for evaluating soft magnetic materials.

Background Art

[0002] Soft magnetic materials are processed into a desired shape and then combined with a coil to form an electromagnet, which is applied to various industrial equipment and medical equipment. As the functions and accuracies required for these industrial and medical equipment become higher, the accuracy required for electromagnets is also increasing.

[0003] In the case of a scanning electron microscope (SEM) as an example of industrial equipment, for an electromagnetic lens that controls the trajectories of primary electrons and secondary electrons, it is required to be miniaturized with good controllability, and to minimize the variation (machine difference) in performance between devices to stabilize the quality.

[0004] Patent Document 1 describes that the miniaturization of a motor is achieved by improving the excitable magnetic flux density (saturation magnetic flux density).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In order to minimize the variation (machine difference) in performance between devices and stabilize the quality, it is desirable to minimize the variation in the characteristics of the magnetic material (soft magnetic material) used in the electromagnet.

[0007] In a scanning electron microscope (SEM), in order to reduce variation in machine differences and stabilize quality, it is important to suppress the magnetic characteristics of the soft magnetic material of the electromagnet (objective lens), particularly the variation in coercive force.

[0008] Patent Document 1 describes achieving miniaturization of a motor by improving the excitable magnetic flux density (saturation magnetic flux density), but does not touch on suppressing the magnetic characteristics of the soft magnetic material of the electromagnet, particularly the variation in coercive force, to minimize the variation in performance (machine differences) between devices and stabilize quality.

[0009] The quality of the soft magnetic material can be managed with a mill sheet, but in order to evaluate the variation in the coercive force (Hc) of the soft magnetic material, it is necessary to measure the magnetic characteristics, which takes time. Also, if the electron lens incorporated in the device does not exhibit the expected performance, a backward process of removing the electron lens from the device occurs, increasing the man-hours of work.

[0010] The present invention solves the above-described problems of the prior art and provides an evaluation method and evaluation system for a soft magnetic material that enables evaluation of the magnetic characteristics of the soft magnetic material used in an electromagnet, particularly the variation in coercive force, at a stage before assembling into products such as an electron lens.

Means for Solving the Problems

[0011] In order to solve the above-described problems, in the present invention, the structure of the soft magnetic material is imaged by an imaging unit to obtain a crystal structure image of the soft magnetic material, and the obtained crystal structure image of the soft magnetic material is processed by an information processing system and compared with the value of the measured coercive force variation to evaluate the coercive force variation of the soft magnetic material, and information regarding the evaluated coercive force variation of the soft magnetic material is displayed on a display terminal, which is an evaluation method for the soft magnetic material.

[0012] Also, in order to solve the above problems, in the present invention, an evaluation system for a soft magnetic material is configured to include an imaging unit that images the surface of the soft magnetic material to obtain a crystal structure image of the soft magnetic material, an information processing system that processes the crystal structure image of the soft magnetic material imaged by this imaging unit to evaluate the variation in the coercive force of the soft magnetic material, and a display terminal that displays information regarding the variation in the coercive force of the soft magnetic material evaluated by this information processing system.

Effect of the Invention

[0013] According to the present invention, it becomes possible to determine the magnetic properties of the soft magnetic material used for the electromagnet, particularly the variation in the coercive force, from the crystal structure image obtained by imaging the soft magnetic material, and it is made possible to evaluate the magnetic properties of the soft magnetic material, particularly the variation in the coercive force, at the stage before assembling it into the product.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

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Figure 6

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Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0015] When a permendur material, which is an alloy of iron (Fe) and cobalt (Co), is used as the soft magnetic material, particles of various sizes appear on the surface of the soft magnetic material. An example of the grain boundary image 11 of the permendur material is shown in FIG. 1(a).

[0016] In the grain boundary image 11 of FIG. 1(a), it can be seen that particles 111 with a relatively large particle size and particles 112 with a relatively small particle size are mixed on the material surface.

[0017] FIG. 1(b) shows a box plot: 12 representing the distribution of the particle size (particle diameter) of the particles in this grain boundary image 11. In FIG. 1(b), the vertical axis indicates the particle size, and the unit is μm. From this figure, it can be seen that the portion 121 from 25% to 75% of the particle size distribution is in the range of 20 μm to 60 μm, the median value 122 of the size is 35 μm, and the average value 123 is 45 μm.

[0018] Also, the graph 13 in Fig. 1(c) shows the particle size distribution represented by a histogram. The histogram in Fig. 1(c) divides the particle size into 10-μm pitches and represents it with histogram 131. From histogram 131, peaks can be confirmed at two locations: 20 μm to 40 μm and 60 μm. Also, curve 132 is the result of fitting the distribution represented by histogram 131 with a log-normal distribution curve. It can be seen that there is a peak in the distribution between 20 μm and 30 μm, that it is mostly distributed in the range of 10 μm to 60 μm, and that the larger ones are distributed up to about 150 μm. However, it can be seen that this fitting does not reproduce the two peaks that can be confirmed in the histogram. Also, the two peaks cannot be expressed in the box-and-whisker plot described above.

[0019] As a result of evaluating various particle size distributions, it was found that there is a certain relationship between the crystal particle size distribution and the variation (range of variation) of the coercive force.

[0020] That is, as shown in graph 21 of Fig. 2, a linear relationship represented by line 23 was found between the value obtained by dividing the first quartile in the distribution (range of variation) of particle size 22 appearing on the surface by the average value of the particle size and the coefficient of variation of the coercive force (the value obtained by dividing the standard deviation of the coercive force by the average value of the coercive force).

[0021] That is, it was found that the smaller the value obtained by dividing the first quartile in the distribution of particle size 22 by the average value of the particle size, the smaller the coefficient of variation of the coercive force and the smaller the variation of the coercive force, and conversely, the larger the value obtained by dividing the first quartile in the distribution of particle size 22 by the average value of the particle size, the larger the coefficient of variation of the coercive force and the larger the variation of the coercive force.

[0022] From this, by obtaining the relationship corresponding to the straight line 23 in FIG. 2 from the relationship between the particle size distribution obtained by analyzing the image obtained by inspecting the soft magnetic material with an optical microscope, a magnetic force microscope (Magnetic Force Microscopy; MFM), etc., and the coercive force of the soft magnetic material, for a new soft magnetic material, without actually measuring the coercive force, by analyzing the image obtained by inspecting the material with an optical microscope or the like, it can be understood that the variation in the coercive force of this new soft magnetic material can be estimated.

[0023] The present invention has been made based on the above-described new findings, and for a soft magnetic material used in an electron lens or the like, the variation in the magnetic characteristics (coercive force) of the soft magnetic material can be relatively easily determined from an image obtained by imaging the soft magnetic material instead of magnetic measurement.

[0024] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In all the drawings for explaining this embodiment, those having the same function are denoted by the same reference numerals, and the repeated description thereof will be omitted in principle.

[0025] However, the present invention is not to be construed as being limited to the description of the embodiments shown below. It will be easily understood by those skilled in the art that the specific configuration can be changed without departing from the spirit or gist of the present invention.

Example

[0026] FIG. 3 shows a schematic configuration of an evaluation system 100 for evaluating the magnetic characteristics of the soft magnetic material according to this example.

[0027] The evaluation system 100 according to this example includes a sample stage 1 on which a sample 20 is placed, an imaging unit 2 that images the surface of the sample 20 placed on the sample stage 1, an information processing system 8 that processes the image of the sample 20 imaged by the imaging unit 2, and an image display terminal 9 that displays the information processed by the information processing system 8.

[0028] The imaging unit 2 includes a light source 3, a half mirror 4 that reflects part of the light emitted from the light source 3 toward the sample 20 placed on the sample stage 1 and transmits part of the light reflected by the sample 20, and a detector 5 that receives the reflected light from the sample 20 transmitted through the half mirror 4 and detects an image of the surface of the sample 20.

[0029] The information processing system 8 includes an information processing unit 6 that receives and processes a signal from the detector 5 that has imaged the surface of the sample 20, and an information storage unit 7 that stores the information processed by the information processing unit 6.

[0030] The internal configuration of the information processing unit 6 is shown in FIG. 4. The information processing unit 6 includes a coercive force data storage unit 61, an image storage unit 62, a particle size measurement unit 63, a particle size analysis unit 64, a database 65, a coercive force variation coefficient calculation unit 66, a coercive force dispersion evaluation unit 67, a network adapter 68, and a CPU 69. These are connected to each other by a common line 60 and are connected to a network 70.

[0031] In the coercive force data storage unit 61, data on the coercive force at a plurality of locations of the sample 20 obtained by measuring with a coercive force measuring device (for example, a direct current magnetization measuring device), not shown, mounted on the sample stage 1, is stored in association with the sample 20.

[0032] An image of the sample 20 captured by the imaging unit 2 (corresponding to the grain boundary image 11 in FIG. 1) is stored in the image storage unit 62. In the particle size measurement unit 63, the diameter of particles (corresponding to the particles 111 and 112 in FIG. 1) on the surface of the sample 20 is measured from the image of the sample 20 stored in the image storage unit 62. Here, the measurement of the particle size on the surface of the sample 20 from the image of the sample 20 is calculated using general image analysis software.

[0033] The information on the particle size measured by the particle size measurement unit 63 is sent to the particle size analysis unit 64, where the first quartile and the average value of the particle diameters in the particle size distribution are obtained, and a value obtained by dividing the value of the first quartile by the average value of the particle diameters (hereinafter, this is referred to as the particle size index value) is calculated.

[0034] On the other hand, in the coercive force variation coefficient calculation unit 66, the coercive force variation coefficient of the sample 20 (the value obtained by dividing the standard deviation of the variation in coercive force by the average value of the coercive force) is calculated from the coercive forces at a plurality of locations of the sample 20 stored in the coercive force data storage unit 61.

[0035] The particle size index value obtained by the particle size analysis unit 64 is sent to the database 65 in association with the information on the coercive force variation coefficient calculated by the coercive force variation coefficient calculation unit 66.

[0036] After a predetermined number of pieces of information on the particle size index value associated with the information on the coercive force variation coefficient are accumulated in the database 65, these data are sent to the coercive force variation evaluation unit 67. In the coercive force variation evaluation unit 67, the relationship between the coercive force variation coefficient and the particle size index value, such as the straight line 23 in FIG. 2, is obtained by performing a regression analysis on the variation in the combination of the coercive force variation coefficient and the particle size index value, and stored in the database 65.

[0037] The operations of the coercive force data storage unit 61, the image storage unit 62, the particle size measurement unit 63, the particle size analysis unit 64, the database 65, the coercive force variation coefficient calculation unit 66, and the coercive force variation evaluation unit 67 are controlled by the CPU 69 connected by the common line 60.

[0038] A procedure for creating a database for evaluating the variation in the coercive force of the sample 20 from the crystal structure image of the sample 20 using such an evaluation system 100 will be described with reference to the flowchart of FIG. 5.

[0039] In creating the database, since data is acquired for a plurality of samples, n is set to 1 in S501, and the coercive forces at a plurality of locations of the first sample 20 are measured using a coercive force measuring means (not shown) and stored in the coercive force data storage unit 61 (S502). At the same time, the standard deviation and the average value of the measured coercive force are obtained in the coercive force variation coefficient calculation unit 66.

[0040] Next, the sample 20 for which the coercive force has been measured is placed on the sample stage 1 of the evaluation system 100 shown in FIG. 3, and the crystal structure image of the sample 20 is captured by the imaging unit 2 and recorded in the information processing unit 6 (S503). Specifically, the light from the light source 3 is irradiated onto the sample 20 placed on the sample stage 1, the crystal structure image is detected by the detector 5, and the data of the detected crystal structure image is stored in the image storage unit 62 of the information processing unit 6.

[0041] Next, in the particle size measurement unit 63 of the information processing unit 6, the data of the crystal structure image stored in the image storage unit 62 is processed to measure the particle size included in this crystal structure image. In the particle size analysis unit 64, the particle size distribution is analyzed to obtain the particle size of the first quartile and the average value of the particle size (S504).

[0042] Next, it is determined whether the value of n has reached a preset N (S505). If it has not reached N (No), 1 is added to n (S508) and the process returns to S502.

[0043] On the other hand, when the value of n has reached the preset N (Yes), the process proceeds to the next step, the relationship between the coefficient of variation of the coercive force and the first quartile / average particle size is evaluated, and the relationship between the coefficient of variation of the coercive force and the particle size index value as shown by the straight line 23 in FIG. 2 is obtained (S506), and it is stored in the database 65 (S507).

[0044] Next, a method for estimating the variation in the coercive force from the crystal structure image of the sample 20 formed of a soft magnetic material using the database created in this way will be described.

[0045] FIG. 6 shows the flow of processing when the present invention is applied to the incoming inspection performed when purchasing a soft magnetic material from a material manufacturer.

[0046] First, for the incoming soft magnetic material, an imaging unit 2 of the evaluation system 100 shown in FIG. 3 acquires a crystal structure image of the soft magnetic material (S601). Using the particle size data measured by a particle size measurement unit 63, a particle size analysis unit 64 analyzes the particle size (S602), obtains the first quartile and the average particle size (S603), and determines the magnetic coercivity variation coefficient from the relationship between the magnetic coercivity variation coefficient and the particle size index value stored in the database (corresponding to the straight line 23 in FIG. 2). Then, it is determined whether the obtained magnetic coercivity variation coefficient is smaller than a preset reference value (S604).

[0047] If, as a result of the determination, the obtained magnetic coercivity variation coefficient is larger than the preset reference value (NG), it is determined that the acceptance reference value is not met, and the incoming soft magnetic material is returned to the manufacturer (S605).

[0048] On the other hand, if the obtained magnetic coercivity variation coefficient is smaller than the preset reference value (OK), since the acceptance reference value is met, the acceptance of the incoming soft magnetic material is approved (S606).

[0049] For the incorporated soft magnetic material, according to the magnitude of the magnetic coercivity variation coefficient, it is divided into those with a magnetic coercivity variation coefficient A determination that is closer to 0 than the reference value and those with a magnetic coercivity variation coefficient B determination that is closer to the reference value. The soft magnetic material with a magnetic coercivity variation coefficient A determination is adopted in the process corresponding to the product that requires a relatively small variation range of the magnetic coercivity. After going through the component manufacturing process (S607), it is assembled into the product in the product assembly process (S608).

[0050] On the other hand, for the soft magnetic material determined to have a magnetic coercivity variation coefficient B, it is adopted in the process corresponding to the product that allows a relatively large variation range of the magnetic coercivity. After going through the component manufacturing process (S609), it is assembled into the product in the product assembly process (S610).

[0051] In this case, since it is known whether the soft magnetic material used in the assembled product is of type A determination or type B determination, the product to be applied can be changed according to the magnitude of the variation range of the magnetic coercivity required for each product.

[0052] Next, a procedure for evaluating the coercivity variation coefficient, which is performed at the stage of processing the soft magnetic material that has passed the acceptance inspection and been delivered as described with reference to FIG. 6, will be described with reference to FIG. 7.

[0053] Regarding the soft magnetic material that has passed the acceptance inspection and been delivered as described with reference to FIG. 6, even if it has been judged as A or B, there may be portions within the plane of the material where the coercivity variation coefficient is large (where the variation in coercivity is large) or where the coercivity variation coefficient is small (where the variation in coercivity is small).

[0054] That is, among the members evaluated as A in the acceptance inspection described with reference to FIG. 6, there may be portions where the coercivity variation coefficient at the B evaluation level is large, or among the members evaluated as B, there may be portions where the coercivity variation coefficient at the A evaluation level is small.

[0055] Therefore, as shown in FIG. 7, before processing the soft magnetic material, the distribution of the coercivity variation coefficient is examined for the entire surface of the soft magnetic material to be processed, and regions with large and small variations in coercivity within the plane of the soft magnetic material to be processed are discriminated. This makes it possible to identify the region to be processed for products that require small variation in coercivity and the region to be processed for products that are acceptable even with relatively large variation in coercivity.

[0056] The flow of FIG. 7 will be described below. First, the entire surface of the soft magnetic material to be processed is sequentially imaged with the field of view size of the detector 5 in the imaging unit 2 of the evaluation system 100 shown in FIG. 3, and images are comprehensively acquired for the entire surface of the soft magnetic material to be processed (S701).

[0057] Next, the information processing unit 6 processes the acquired images, analyzes the particle size of the soft magnetic material to be processed for each image (each imaging region) (S702), obtains the first quartile and the average particle size of the particle size in each image (each imaging region), and extracts a particle size index value obtained by dividing the first quartile by the average particle size value (S703).

[0058] Next, based on the particle size index value obtained in S703, the coercivity variation coefficient in the range of each image (each imaging region) is obtained from the relationship between the coercivity variation coefficient and the particle size index value shown by the straight line 23 in FIG. 2 stored in the database 65, and it is determined whether the obtained coercivity variation coefficient is greater than or less than a preset threshold value (S704).

[0059] As a result of the determination, if the coercivity variation coefficient is smaller than the preset threshold value (YES), it is determined that the coercivity variation is small in the range of the image (each imaging region) (S705), and if the coercivity variation coefficient is greater than the preset threshold value (NO), it is determined that the coercivity variation is large in the range of the image (each imaging region) (S706).

[0060] Next, for each of those determined to have a small coercivity variation (S705) and those determined to have a large coercivity variation (S706), a coercivity variation mapping of the area where the coercivity is analyzed is created (S707), and the result is marked on the GUI (Graphic User Interface) (S708).

[0061] FIG. 8 shows an example of a GUI 80 that displays the results of the inspection during the material acceptance inspection described in the flowchart of FIG. 6.

[0062] The GUI 80 includes an information input area 82, an acquired image display area 83 for displaying the acquired images of the material surface, a particle size distribution display area 84 for displaying information regarding the particle size included in the image obtained by processing the grain boundary image of the acquired material by the information processing unit 6, a coercivity variation coefficient correlation formula display area 85 for displaying information regarding the coercivity variation coefficient of the sample, an analysis result display area 86 for displaying the analysis result, and a determination result display area 87 for displaying the determination result.

[0063] The information input area 82 is provided with a material name input unit 821 for inputting the material name of the material to be inspected, a composition ratio data input unit 822 for inputting data on the composition ratio of the material input to the material name input unit 821, a mill sheet number input unit 823 for inputting the number of the mill sheet attached to the material input to the material name input unit 821, a coercive force input unit 824 for inputting the coercive force of the material to be inspected displayed on the mill sheet, a magnetic flux density input unit 825 for inputting the magnetic flux density, a magnetic permeability input unit 826 for inputting the magnetic permeability, and a DB call unit 827 for calling the information stored in the database 65.

[0064] In the acquired image display area 83, an image 831 of the material surface acquired by the imaging unit 2 and stored in the image storage unit 62 of the information processing unit 6 is displayed. In the particle size distribution display area 84, a graph display area 841 for displaying data corresponding to a histogram 131 of the particle size distribution on the material surface in the image 831 measured by the particle size measurement unit 63 of the information processing unit 6 from the image 831 marked in the acquired image display area 83 and analyzed by the particle size analysis unit 64 as described in FIG. 1(c), and a curve 132 obtained by fitting the data of this histogram 131 with a lognormal distribution curve, and a box-and-whisker plot display area 842 for displaying the particle size distribution displayed in this histogram as a box-and-whisker plot are provided.

[0065] In the coercive force variation coefficient correlation formula display area 85, a graph 851 showing the relationship between the particle size index value obtained by dividing the first quartile of the particle size by the average value of the particle size and the coercive force variation coefficient based on the data corresponding to the material input to the material name input unit 821 among the data stored in the database 65 by clicking the DB call unit 827 of the information input area 82, and the material name 854 input to the material name input unit 821 are displayed. On the graph 851, a straight line 852 obtained by linearly approximating the relationship between the value obtained by dividing the first quartile of the particle size by the average value of the particle size and the coercive force variation coefficient, and a reference value for determining the coercive force variation coefficient at the time of acceptance inspection are displayed as a straight line 853.

[0066] In the analysis result display area 86, the image 831 of the material surface displayed in the acquired image display area 83 is measured by the particle size measurement unit 63 of the information processing unit 6, analyzed by the particle size analysis unit 64, and evaluated by the coercivity variation evaluation unit 67. The result 863 is displayed in the same graph as the graph 851, and the average value display unit 865 that displays the average value of the particle size corresponding to the evaluated result 863, and the first quartile data display unit 866 that displays the data of the first quartile of the particle size distribution are provided. In the graph 861, a straight line 862 corresponding to the straight line 852 of the graph 851 and a straight line 864 corresponding to the straight line 853 indicating the reference value for the determination of the coercivity variation coefficient during the incoming inspection are displayed.

[0067] In the determination result display area 87, a coercivity variation display unit 871 that displays the variation of the coercivity corresponding to the evaluated result 863 marked on the graph 861 of the analysis result display area 86, and an applicable product display unit 872 that displays the product name of the object to be processed and incorporated by processing the soft magnetic material to be inspected this time are displayed. A determination display unit 873 that displays the result of determining whether the material evaluated by the coercivity variation evaluation unit 67 can be accepted as a material applicable to the product displayed by the applicable product display unit 872, and a DB registration button 874 for registering the determined result in the database 65 are provided.

[0068] In this way, since the evaluation result of the coercivity variation range of the material obtained based on the crystal structure image obtained by imaging the surface of the material at the time of material receipt is marked on the GUI80, it is possible to determine whether the material can be accepted relatively quickly and easily compared to the case of measuring using the conventional coercivity measurement means. Furthermore, an optimal processing policy can be established.

[0069] FIG. 9 shows a GUI90 showing the result of evaluating the coercivity variation coefficient performed at the stage of processing the soft magnetic material that has passed the incoming inspection and has been delivered as described in the flowchart of FIG. 7.

[0070] The GUI 90 shown in FIG. 9, similar to the GUI 80 described in FIG. 8, includes an information input area 92, an acquired image display area 93 for displaying an image of the acquired material surface, a particle size distribution display area 94 for displaying information regarding the particle size included in the image obtained by processing the image of the acquired material surface by the information processing unit 6, a coercive force variation coefficient correlation formula 95 and an analysis result display area 96 for displaying information regarding the coefficient of variation of the coercive force of the sample, and a determination result display area 97 for displaying the determination result.

[0071] In a portion corresponding to the analysis result display area 86 for displaying the analysis result of FIG. 8, a coercive force variation mapping display area 96 showing the variation in the coercive force at locations corresponding to a plurality of images is displayed.

[0072] The information input area 92 includes a material name input unit 921 for inputting the name of the material to be inspected, a composition ratio data input unit 922 for inputting data on the composition ratio of the material input to the material name input unit 921, a mill sheet number input unit 923 for inputting the number of the mill sheet attached to the material input to the material name input unit 921, a coercive force input unit 924 for inputting the coercive force of the material to be inspected displayed on the mill sheet, a magnetic flux density input unit 825 for inputting the magnetic flux density, a permeability input unit 926 for inputting the permeability, and a DB call unit 927 for calling information stored in the database 65.

[0073] In the acquired image display area 93, an image display unit 931 for displaying an image of the material surface acquired by the imaging unit 2 and stored in the image storage unit 62 of the information processing unit 6, and a display area setting unit 932 for setting the area for displaying this image are displayed.

[0074] In the particle size distribution display area 94, the graph display area 941 displays data corresponding to the histogram 131 of the particle size distribution on the material surface measured by the particle size measurement unit 63 of the information processing unit 6 from the image displayed on the image display unit 931 of the acquired image display area 93 and analyzed by the particle size analysis unit 64, as explained in FIG. 1(c), and the curve 132 obtained by fitting the data of this histogram 131 with a log-normal distribution curve. The box-and-whisker plot display area 942 displays the distribution of the particle sizes displayed in this histogram as a box-and-whisker plot.

[0075] However, when the all-region button 962 in the coercivity variation mapping display area 96 described later is set, the graph display area 941 displays the distribution of the particle sizes of the entire imaged area of the material to be inspected as a histogram, and the curve obtained by fitting it with a log-normal distribution curve corresponding to the histogram is displayed. Also, in the box-and-whisker plot display area 942, data corresponding to the distribution of the particle sizes of the entire region is displayed.

[0076] In the coercivity variation coefficient correlation formula and analysis result display area 95, by clicking the DB call unit 927 in the information input area 92, among the data stored in the database 65, based on the data corresponding to the material name input in the material name input unit 921, the graph 951 showing the relationship between the particle size index value obtained by dividing the first quartile of the particle size by the average value of the particle size and the coercivity variation coefficient as shown in FIG. 2 and the material name 955 input in the material name input unit 921 are displayed.

[0077] In the graph 951, the straight line 952 obtained by linearly approximating the relationship between the particle size index value obtained by dividing the first quartile of the particle size by the average value of the particle size and the coercivity variation coefficient stored in the database 65 and the data 953 corresponding to a plurality of regions marked in the coercivity variation mapping display area 96 are displayed. Also, in the graph 951, the reference value for determining the coercivity variation coefficient during the acceptance inspection is displayed as the straight line 954.

[0078] In the coercive force variation mapping display area 96, the results of analyzing the images of the material surfaces in a plurality of regions are displayed for each region corresponding to the image captured by the imaging unit 2, distinguishing between cases above (large coercive force variation), for example, the straight line 954 marked on the graph 951, and cases below (small coercive force variation) according to the magnitude of the coercive force variation. A mapping display unit 961 is provided, and an all-region button 962 and a designated-region button 963 for designating the regions marked on this mapping display unit 961 are displayed.

[0079] When the all-region button 962 is clicked, the evaluation result of the coercive force variation for the entire region imaged by the imaging unit 2 for the material corresponding to the mill sheet input in the mill sheet number input unit 923 is displayed on the image display unit 931. When the designated-region button 963 is clicked, the evaluation result of the coercive force variation in the region set by the display region setting unit 932 and the surrounding regions is displayed.

[0080] In the determination result display area 97, a coercive force variation display unit 971 for displaying the variation in the coercive force of the regions marked on the mapping display unit 961 of the coercive force variation mapping display area 96, and an applicable product display unit 972 for displaying the product name of the product to be processed and incorporated by processing the soft magnetic material to be inspected this time are displayed. A determination display unit 973 for displaying the result of determining whether the material evaluated by the coercive force variation evaluation unit 67 is applicable as a material for the product displayed on the applicable product display unit 972, and a DB registration button 974 for registering the determined result in the database 65 are provided.

[0081] In this way, by displaying the evaluation result of the coercive force variation range of the material obtained based on the crystal grain size image obtained by imaging the surface of the material before processing the soft magnetic material on the GUI 90, it is possible to individually evaluate the variation in the coercive force for each material and then perform processing.

[0082] Accordingly, according to this embodiment, since the range of variation in the coercive force of the soft magnetic material in the assembled state of the processed product is guaranteed, it is possible to prevent the occurrence of a process of disassembling the once-assembled product due to a defect in the range of variation in the coercive force of the soft magnetic material (when the range of variation in the coercive force is larger than the reference value) and replacing the parts after assembly.

[0083] Also, according to this embodiment, since the variation in the coercive force is evaluated individually for each material and then processed and assembled into a product, stable quality can be ensured for the assembled product.

[0084] Note that in this embodiment, a method for evaluating the variation in the coercive force of the soft magnetic material at the stage before processing has been described. However, it may be possible to evaluate the variation in the coercive force at the stage after processing the soft magnetic material and before incorporating it into the product. By evaluating after processing, it is possible to evaluate the variation in the coercive force in a state closer to the product.

[0085] When this embodiment is applied to an electronic lens, since the variation in the coercive force of the soft magnetic material can be evaluated at the stage before winding the coil, it is possible to prevent the occurrence of a process of going back for the product after winding the coil by using the soft magnetic material that has passed the evaluation.

[0086] Also, although the case of a Permendur material as the soft magnetic material has been described, iron or an electromagnetic steel sheet can also be used.

[0087] As described above, the invention made by the present inventor has been specifically described based on the embodiments. However, it goes without saying that the present invention is not limited to the above embodiments and can be variously modified without departing from the gist thereof. For example, the above-described embodiments have been described in detail for easy understanding of the present invention and are not necessarily limited to those having all the configurations described. Also, it is possible to add, delete, or replace a part of the configuration of each embodiment with other configurations.

Explanation of Reference Numerals

[0088] 1 Sample stage 2 Imaging unit 3 Light source 4 Half mirror 5 Detector 6 Information processing unit 7 Information storage unit 8 Information processing system 9 Image display terminal 60 Common line 61 Coercive force data storage unit 62 Image storage unit 63 Particle size measurement unit 64 Particle size analysis unit 65 Database 66 Coercive force variation coefficient calculation unit 67 Coercive force dispersion evaluation unit 68 Network adapter 69 CPU 70 Network 80,90 GUI

Claims

A method for evaluating a soft magnetic material, comprising: imaging the surface of the soft magnetic material with an imaging unit to obtain a crystal structure image of the soft magnetic material; processing the obtained crystal structure image of the surface of the soft magnetic material with an information processing system to evaluate the variation in the coercive force of the soft magnetic material; displaying information regarding the evaluated variation in the coercive force of the soft magnetic material on a display terminal; In the information processing system, the crystal structure image of the surface of the soft magnetic material imaged by the imaging unit is processed by an image processing unit to measure the particle size of the soft magnetic material and determine the variation in the particle size. The relationship between the variation in the coercive force and the variation in the particle size measured in advance for a soft magnetic material different from the soft magnetic material is stored in a storage unit. Based on the data of the variation in the particle size of the soft magnetic material obtained by the image processing unit and the relationship between the variation in the coercive force and the variation in the particle size stored in the storage unit, a coercive force variation evaluation unit evaluates the variation in the coercive force of the soft magnetic material. A method for evaluating a soft magnetic material, characterized by the above. **Claim 2** In the method for evaluating a soft magnetic material according to Claim 1, as information regarding the variation in the coercive force of the soft magnetic material to be displayed on the display terminal, the variation in the coercive force of the soft magnetic material is divided for each region of the soft magnetic material and includes a mapping display. A method for evaluating a soft magnetic material, characterized by the above. **Claim 3** In the method for evaluating a soft magnetic material according to Claim 1, as information regarding the variation in the coercive force of the soft magnetic material to be displayed on the display terminal, it further includes the crystal structure image of the surface of the soft magnetic material imaged by the imaging unit and information regarding the distribution of the particle size on the surface of the soft magnetic material obtained by processing the crystal structure image of the surface of the soft magnetic material. A method for evaluating a soft magnetic material, characterized by the above. **Claim 4** In the method for evaluating a soft magnetic material according to Claim 1, as information regarding the variation in the coercive force of the soft magnetic material to be displayed on the display terminal, it includes the result of evaluating the variation in the coercive force of the soft magnetic material. A method for evaluating a soft magnetic material, characterized by the above. A system for evaluating the coercive force of a soft magnetic material, comprising: an imaging unit that images the surface of the soft magnetic material to obtain a crystal structure image of the soft magnetic material; An information processing system that processes the crystal structure image of the surface of the soft magnetic material captured by the imaging unit to evaluate the variation in the coercive force of the soft magnetic material, A display terminal that displays information regarding the variation in the coercive force of the soft magnetic material evaluated by the information processing system, and is provided with, The information processing system includes an image processing unit that processes the crystal structure image of the surface of the soft magnetic material captured by the imaging unit to measure the particle size of the soft magnetic material and obtain the variation in the particle size, a storage unit that stores in advance the relationship between the variation in the coercive force and the variation in the particle size measured for a soft magnetic material different from the soft magnetic material, and a coercive force variation evaluation unit that evaluates the variation in the coercive force of the soft magnetic material based on the data of the variation in the particle size of the soft magnetic material obtained by the image processing unit and the relationship between the variation in the coercive force and the variation in the particle size stored in the storage unit. A coercive force evaluation system for a soft magnetic material, characterized by the above.

6. In the coercive force evaluation system for a soft magnetic material according to claim 5, The display terminal is characterized in that, as information regarding the variation in the coercive force of the soft magnetic material, the variation in the coercive force of the soft magnetic material is divided for each region of the soft magnetic material and mapped and displayed. A coercive force evaluation system for a soft magnetic material.

7. In the coercive force evaluation system for a soft magnetic material according to claim 5, The display terminal is characterized in that, as information regarding the variation in the coercive force of the soft magnetic material, the crystal structure image of the surface of the soft magnetic material captured by the imaging unit and information regarding the distribution of the particle size of the surface of the soft magnetic material obtained by processing the crystal structure image of the surface of the soft magnetic material are further displayed. A coercive force evaluation system for a soft magnetic material.

8. In the coercive force evaluation system for a soft magnetic material according to claim 5, The display terminal is characterized in that, as information regarding the variation in the coercive force of the soft magnetic material, the result of evaluating the variation in the coercive force of the soft magnetic material is displayed. A coercive force evaluation system for a soft magnetic material.

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