JP3705095B2 - Method and apparatus for evaluating color tone of design pattern colored on object surface - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a color tone evaluation method and apparatus for evaluating the color tone of a design pattern by coloration of dot-like color elements applied to an object surface by laser decoration or the like.
[0002]
[Prior art]
Conventionally, when evaluating the color tone of the surface of an object on which a design pattern is colored with dot-like color elements, there has been a problem that the measured value changes greatly even if the position of the measurement region is slightly shifted. The reason is that, for example, even in a measurement region having the same area, as shown in FIG. 14, the color tone measurement values differ depending on whether a large number of dot-like color elements are included in the measurement area.
[0003]
In a conventional color tone measuring device, a region for measuring a color tone is determined and positioned to measure the color tone. For example, an apparatus disclosed in Japanese Patent Application Laid-Open No. 10-329308 measures a moving distance of an object to be measured with a rotary encoder and measures a color tone by integrating a spectral amount according to a predetermined travel length. It measures the color tone.
[0004]
According to this apparatus, since an area to be measured is determined from the amount of movement and the color is measured after being accurately measured, an average color measurement result can be obtained in a relatively large measurement area.
[0005]
[Problems to be solved by the invention]
However, based on the design data of the product design, the surface of a molded product, metal, etc. is irradiated with laser light sequentially, and the laser light irradiation part is colored to mark the design by laser decoration. The appearance of the object surface with the design pattern colored by the color element may not only be different in color tone and uneven color due to fluctuations in the laser processing conditions, but the same laser processing conditions must be maintained accurately. However, (1) if the object to be colored is different, the color tone will be different due to differences in material lots, molding conditions, leaving time after molding, etc. If they are different, surface roughness and color developability are uneven due to partial differences in molding conditions and material variations, and color unevenness often occurs.
[0006]
For this reason, it is necessary to accurately evaluate the color tone of fine partial areas and minute areas, but the color tone of the object surface colored with a pattern pattern by fine dot-like color elements such as by laser decoration is fine. Even if the color tone of the decorative part and the color tone of the non-decorated part are the same in a small measurement area, it will be measured as a mixed color of the dotted decorative part and the non-decorative part that is the background, If the ratio of the decorative part and the non-decorative part is different, there is a problem that the measured color tone is different.
[0007]
However, in the conventional method, it has been difficult to accurately evaluate the color tone of such a small region composed of the decorative portion and the non-decorative portion.
[0008]
The present invention has been proposed to solve such a problem, and a color tone evaluation method capable of accurately evaluating the color tone of an inspection area of an object surface colored with a pattern pattern by dot-like color elements, and its An object is to provide an apparatus.
[0009]
[Means for Solving the Problems]
In order to solve the above problem, the color tone evaluation method according to claim 1 includes dot-like color elements. Figure with periodicity Scan the spectroscopic camera on the surface of the object with the design pattern applied to capture the image of the design pattern, and perform arithmetic processing on the captured image according to the following procedure to determine the quality of the design pattern color. Features.
[0010]
1) When an image having a pattern pattern is divided into image processing units, dot-like color elements are uniformly included therein, and the positional relationship between the pattern pattern and the image processing unit is synchronized, or one or more cycles The pattern composed of the pattern of Image of the pattern of the object surface captured as an inspection area through the spectroscopic camera In order of attention Break down.
2) For each image processing unit in the inspection area, the spectral intensity distribution information decomposed into color components by the spectroscopic camera is subjected to predetermined calculation processing to be sequentially converted into color tone information.
3) The average value of the tone information is sequentially calculated for each field of view, and it is determined whether each average value does not exceed a predetermined upper limit value and lower limit value set in advance for each field of view.
4) The average value calculated for each field of interest And the difference value between the average value of the previous visual field of interest It is judged whether or not the variation range is exceeded.
5) When the judgment condition is satisfied by using at least one of the above conditions 3) and 4) or a combination thereof, the design pattern applied to the object surface is good. It is determined to be bad.
[0011]
Here, the image processing unit is a minimum unit for calculating spectral intensity distribution information, and is generally calculated in units of one pixel.
[0012]
In claim 2, dot-like color elements are included by laser decoration. Figure with periodicity The spectroscopic camera is scanned over the surface of the object on which the pattern pattern has been applied, the image of the pattern pattern on the surface of the object is captured, and the captured image is processed according to the following procedure to obtain the color tone of the pattern pattern. It is characterized by judging pass / fail.
[0013]
1) When an image having a pattern pattern is divided into image processing units, dot-like color elements are uniformly included therein, and the positional relationship between the pattern pattern and the image processing unit is synchronized, or one or more cycles The pattern composed of the pattern of Image of the pattern of the object surface captured as an inspection area through the spectroscopic camera In order of attention Break down.
2) For each image processing unit in the inspection area, the spectral intensity distribution information decomposed into color components by the spectroscopic camera is subjected to predetermined calculation processing to be sequentially converted into color tone information.
3) The average value of the tone information is sequentially calculated for each field of view, and it is determined whether each average value does not exceed a predetermined upper limit value and lower limit value set in advance for each field of view.
4) The average value calculated for each field of interest And the difference value between the average value of the previous visual field of interest It is judged whether or not the variation range is exceeded.
5) When the judgment condition is satisfied by using at least one of the above conditions 3) and 4) or a combination thereof, the design pattern applied to the object surface is good. It is determined to be bad.
[0014]
A third aspect of the present invention is the method according to the first or second aspect, wherein the spectroscopic camera is scanned at a predetermined angle with respect to the design pattern on the object surface, and an image of the design pattern on the object surface is captured. In order to reduce the color tone variation due to the shift, it is characterized in that it is sequentially divided into a visual field of interest constituted by a plurality of image processing units.
[0015]
According to claim 4, in any one of claims 1 to 3, the average value is not calculated for the entire visual field of interest, but the average value is calculated separately for each image processing unit depending on whether or not the pattern pattern in the visual field of interest is present. According to the above-mentioned procedures 1) to 5) according to claim 1 or 2, the color tone is evaluated independently of the presence or absence of a design pattern for each visual field of interest.
[0016]
A fifth aspect of the present invention is the method according to any one of the first to fourth aspects, wherein a portion with the smallest amount of change in color tone is set as a start end of a visual field of interest among a series of color tone information calculated and converted for each image processing unit. According to the above-described procedures 1) to 5) according to claim 1 or 2, the design pattern colored on the object surface is evaluated.
[0017]
A sixth aspect of the present invention provides a pattern pattern dot included in a field of interest by capturing an image of an object surface in the spectroscopic camera using a light image scaling unit such as a zoom lens according to any one of the first to fifth aspects. The arrangement of the color elements can be adjusted.
[0018]
According to a seventh aspect of the present invention, in any one of the first to sixth aspects, a process for determining the position of the visual field of interest with respect to the design pattern by performing a difference process on the color tone information is further added.
[0019]
In claim 8, claims 1 to Any of 7 In this case, a color camera is used instead of the spectroscopic camera to capture an image of the design pattern on the object surface.
[0020]
In claim 9, claims 1 to Any of 8 In this case, a specific wavelength component of the symbol pattern is extracted, the position of the symbol pattern is detected, and the field of interest is determined in accordance with the symbol pattern position.
[0021]
The color tone evaluation apparatus according to claim 10 includes a dot-like color element. Figure with periodicity A spectroscopic camera for scanning an object surface colored with a pattern and capturing an image of the pattern pattern on the surface and an image captured by the spectroscopic camera are processed according to the following procedures 1) to 5). Arithmetic processing means.
[0022]
1) When an image having a pattern pattern is divided into image processing units, dot-like color elements are uniformly included therein, and the positional relationship between the pattern pattern and the image processing unit is synchronized, or one or more cycles The pattern composed of the pattern of Image of the pattern of the object surface captured as an inspection area through the spectroscopic camera In order of attention Break down.
2) For each image processing unit in the inspection area, the spectral intensity distribution information decomposed into color components by the spectroscopic camera is subjected to predetermined calculation processing to be sequentially converted into color tone information.
3) The average value of the tone information is sequentially calculated for each field of view, and it is determined whether each average value does not exceed a predetermined upper limit value and lower limit value set in advance for each field of view.
4) The average value calculated for each field of interest And the difference value between the average value of the previous visual field of interest It is judged whether or not the variation range is exceeded.
5) When the judgment condition is satisfied by using at least one of the above conditions 3) and 4) or a combination thereof, the design pattern applied to the object surface is good. It is determined to be bad.
[0023]
The eleventh aspect of the present invention further comprises scanning alignment means for moving at least one of the spectroscopic camera and the object surface colored with the pattern pattern according to claim 10, wherein the scanning alignment means is an image processing unit. The positioning is automatically performed so that the difference amount of the color tone information for each of them becomes small.
[0024]
A twelfth aspect is characterized in that, in any one of the tenth and eleventh aspects, an image of a design pattern on the surface of an object is captured using a color camera instead of the spectroscopic camera.
[0025]
According to a thirteenth aspect of the present invention, in any one of the tenth to twelfth aspects, the spectroscopic camera or the color camera further includes an optical image scaling unit that makes it possible to adjust the arrangement relationship of the dot-like color elements of the pattern pattern to be included in the field of interest. Further, the optical image scaling means is configured to automatically adjust the scaling ratio so that the arrangement of the dot-shaped color elements of the pattern pattern included in the field of interest can be adjusted.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0027]
FIG. 1 is a diagram showing an example of a design pattern in which a surface of a molded product or metal is colored with dot-like color elements by laser decoration as an appearance design of a product. This laser decoration is also intended to give the product a high-class feeling, but such pattern patterns having periodicity and regularity tend to have poor color tone and require more accurate tone evaluation.
[0028]
FIG. 1A shows an object (evaluation target) on which a dot-shaped marking is applied to the surface by a laser, and an enlarged portion surrounded by a circle of reference A is shown in FIG. In addition, although the thing by laser decoration is mentioned as an example here, the object of evaluation is not limited to this, and the thing applied by changing the color by adding energy like laser decoration, ink jet, Also included are those that are colored with a dye attached by dot printing or the like.
[0029]
As can be understood from FIG. 1 (b), a plurality of dots applied by the laser gather to form one line, and the plurality of lines are parallel to form a striped pattern. . Here, the design pattern is not limited to the above-described pattern, but also includes pictures and characters, and the color is not limited to a single color but may be a color.
[0030]
FIG. 2 shows a configuration of a color tone evaluation apparatus for evaluating the color tone of a design pattern laser-decorated on the surface of the object. FIG. 3A shows a configuration of a main part of a spectral camera used in this apparatus. A graph for explaining the color tone (in this case, brightness) is shown in FIG.
[0031]
As shown in FIG. 2, the color tone evaluation apparatus 20 includes a spectral camera 1 that captures a spectral image, an object movement table 2 that constitutes a scanning alignment unit, and information processing that converts the captured spectral image into color tone information. An apparatus 3, an output unit 4 configured with a monitor television and the like, and an input unit 5 configured with a keyboard and the like are provided. Further, the information processing apparatus 3 includes a control unit 3a that controls the spectral camera 1 and the scanning alignment unit 2, a color tone storage unit 3b that stores color tone information of the spectral image, and a color tone calculation unit that calculates and analyzes the color tone information. And an analyzing unit 3c to be configured.
[0032]
Here, the object moving table 2 can move the evaluation object T horizontally and vertically with respect to the spectroscopic camera 1 or rotate it. Here, although the evaluation target T is moved using the object movement table 2, the spectroscopic camera 1 may be moved.
[0033]
As shown in FIG. 3A, the spectroscopic camera 1 includes a prism 1c as a spectroscopic element between a lens 1a and a CCD element 1b. Light that has passed through the slit 1d from the lens 1a is split into light for each wavelength by the prism 1c. As the spectroscopic element, there is a diffraction grating in addition to the prism 1c.
[0034]
If the width of the slit 1d is made sufficiently narrow, the light passing through the slit 1d can be regarded as one line, and when this linear light is split by the prism 1c, light of a specific short wavelength is It reaches each CCD element 1b separately for each angle corresponding to the wavelength.
[0035]
Focusing on one plane of the CCD element 1b, it can be understood that the horizontal direction of the plane is a position axis corresponding to the direction of the slit 1d, and the vertical direction is a wavelength axis indicating the magnitude of the wavelength. The spectral intensity for each wavelength at a certain position is determined by the charge applied to the CCD element at the coordinate position. The third coordinate axis in FIG. 3B, that is, the height of the “mountain” on the plane in the figure represents the spectral intensity for each wavelength. In FIG. 3, the spectral intensity distribution information S relating to this pixel is shown by focusing on one pixel which is the minimum unit for calculating the color tone information, that is, the image processing unit.
[0036]
Here, the spectroscopic camera may be replaced with a normal color camera, and the color output may be calculated by calculating the RGB output value of the color camera. Although the color tone measurement accuracy is lowered, the apparatus is simplified and the cost is reduced. it can.
[0037]
The analysis unit 3c of the information processing device 3 performs predetermined calculation processing on the spectral intensity distribution information S for each pixel and converts it into color tone information. In the predetermined calculation process, for example, spectral information (intensity of each wavelength) decomposed into color components by the spectroscopic camera 1 is converted into XYZ, and a predetermined conversion formula process is further performed to obtain Lab information indicating the color tone. This conversion formula is shown as conversion formula 1 in FIG. 4A and conversion formula 2 in FIG. The color tone information Lab converted for each pixel is stored in the color tone storage unit 3b. The properties indicated by the respective values, L value, a value, and b value of the color tone information Lab are shown in the table of FIG. The L value is a numerical value representing brightness, the a value is a numerical value representing a reddish color, and the b value is represented by a numerical value representing yellow. For example, if the values of a and b are both 0, an achromatic color represented only by lightness L is obtained.
[0038]
Next, a specific color tone evaluation method using the spectral camera 1 will be described with reference to FIGS.
[0039]
As shown in FIG. 6, the spectroscopic camera 1 is arranged on the evaluation target T patterned with the design pattern as shown in FIG. 1, and the spectroscopic image of the inspection region T1 is measured. Further, the spectral camera 1 or the evaluation target T is shifted to the left and right to capture a spectral image while changing the inspection region T1. Based on the spectral image captured by the information processing device 3, the color tone information Lab is calculated for each pixel.
[0040]
FIG. 7A is an enlarged view of a part of the inspection region T1 imaged by the spectroscopic camera 1 in FIG. 6, and FIG. 7B shows the color tone information Lab corresponding to each pixel in FIG. 3 is a graph representing L. Instead of the lightness L, chromaticity a value and b value may be adopted.
[0041]
As shown in FIG. 7B, when attention is paid to the lightness L in the color tone information Lab corresponding to the color elements marked in a dot shape, the lightness L varies. This variation is slightly caused by comparing the marked symbol pattern shown in (a) with the pixel when comparing (1), (2) and (3), and this variation is caused.
[0042]
However, in the pattern (4), the position corresponding to the pixel matches with (1), and the pattern (5) matches with (2). In other words, in the present embodiment, the pattern of the patterned pattern is that the spectral camera pixels and dot markings are synchronized with a period of three linear patterns ((1) to (3)). One period is defined as one target visual field V, and the color tone is evaluated for each target visual field V.
[0043]
The target visual field V is sequentially shifted in the order of (1) to (3), (2) to (4), (3) to (5), and so on, and the moving average value of the color tone information Lab is changed for each target visual field V. Calculate sequentially. Then, the color tone is evaluated according to the following procedure.
[0044]
1) The color tone moving average value of the visual field of interest V is compared with a predetermined upper limit value and lower limit value set in advance, and it is determined whether or not they are within those ranges. Thereby, it can be determined for each field of view V whether the color tone is within a predetermined level range.
[0045]
2) A difference value between the color tone moving average value of the target visual field V and the color tone moving average value of the previous target visual field V is obtained, and whether or not the difference value is within a preset variation range based on the magnitude of the difference value and the tendency of change. Judging.
[0046]
The judgment of 1) is mainly an inspection of whether the color tone of each part of the evaluation object is within the standard range of the non-defective product, and the judgment of 2) is mainly the color unevenness and decoration of each part of the evaluation object. This is for detecting defects such as fading, chipping and deformation of patterns.
[0047]
Detects sudden changes such as fading, chipping, and deformation depending on the size of each difference value, and adds a number of consecutive difference values to obtain a trend value that is obtained sequentially to make comparative smoothness such as color unevenness. Detects any changes.
[0048]
The reference value for determination is set based on the product standard, but may be set as a process standard based on statistical data of good products obtained by measuring a number of good products manufactured in advance in advance. Moreover, a decoration part is evaluation of decoration quality, a non-decoration part is mainly evaluation of shaping | molding quality, and a process specification is set so that each abnormality can be detected.
[0049]
For example, when the determination conditions 1) and 2) are satisfied at the same time, the design pattern applied to the surface of the object is good. Of course, the quality may be judged only by the judgment condition of 1) or 2), or the judgment may be divided into various cases by the combination of 1) and 2). For example, when the color tone of 1) is low, the combination condition is set such that the allowable range of variation of 2) is reduced. This makes it possible to detect a conspicuous defect according to the color tone level.
[0050]
Here, the visual field of interest V is measured while being overlapped, but it is not necessary to overlap such as (1) to (3), (4) to (6),. Of course, in this case, a normal average value, not a moving average value, is calculated and the above determination is made.
[0051]
Moreover, although it judges with the average value of the attention visual field V whole, it divides into the pixel of the marking part M and the pixel of the non-marking part S in the attention visual field V, totals the pixel of each area, and calculates | requires an average value. The marking part M and the non-marking part S may be evaluated. At this time, since the color tone of the boundary portion B between the marking portion M and the non-marking portion S varies, it is better to exclude the boundary portion B and perform the average value calculation.
[0052]
When the average value is calculated and evaluated as a whole, although the individual dot markings have poor color tone, the ratio to the overall color tone is small, and the average value may be judged as good as a result. If the marking part M and the non-marking part S are evaluated separately, such a wrong determination is not made and a highly accurate color tone evaluation can be performed. In addition, the poor color tone of the marking part M is often caused by laser decoration conditions and the like, and the poor color tone of the non-marking part S is often caused by the manufacturing state of the molded product that is the object, and measures are taken. Since the targets to be different are different, it is preferable to evaluate each of the marking part M and the non-marking part S because an accurate cause search and countermeasure can be performed.
[0053]
FIG. 8 is a diagram showing the relationship between the periodicity of the symbol pattern and the visual field V of interest. As shown in FIG. 8 (a), even if the dot pattern has periodicity, the dot pattern on the field of interest is asynchronous, so the brightness varies for each field of interest as shown in FIG. 8 (b). When the dot pattern on the visual field of interest is synchronized, the brightness is almost uniform.
[0054]
Therefore, if the brightness is measured with an optimal field of interest, highly accurate evaluation can be performed.
[0055]
Note that black circles and white circles in FIG. 8 indicate two color dots, and the design pattern may be a mixture of multicolor dots.
[0056]
Further, if the one field of view V shown in FIG. 7A is set so that the starting point is located at the non-marking portion S, the measurement can be stably performed even for a slight misalignment.
[0057]
FIG. 9 is a diagram showing a pattern in which the period of the symbol pattern due to dots changes midway. In the case of such a pattern, since the pattern 1 is synchronized with the pixels of the spectroscopic camera with three linear patterns, the period of three lines is one field of view V, and the pattern 2 is synchronized with two linear patterns. The color tone may be evaluated with this period as one field of view V.
[0058]
Next, a method for evaluating the color tone by adjusting the angle between the spectroscopic camera and the evaluation target will be described with reference to FIG.
[0059]
As shown in FIGS. 10A and 10B, in the case where a plurality of pixels are included in the field of interest, when the area to be measured for each pixel and the arrangement of dots are shifted, (a) and (b) However, as shown in (c), if an angle is provided between the slits of the spectroscopic camera and the evaluation object, the proportion of dots in each pixel varies appropriately, so multiple pixels are averaged. By doing so, the variation in brightness due to the difference between the visual field of interest V and the dots is reduced. This angle can be provided by rotating the object moving table 2.
[0060]
However, when the dots are arranged at equal intervals in the vertical and horizontal directions as shown in FIG. 10, if the angle is set to 45 degrees, the variation increases as in (a) and (b). Variation can be reduced by setting the angle.
[0061]
FIG. 11 is a diagram illustrating an image captured by a spectroscopic camera with a zoom lens attached.
[0062]
Here, the spectroscopic camera 1 is further provided with a zoom lens 1e, and the zoom lens 1e is adjusted so that the sizes of dots and pixels are optimal for color tone evaluation (see FIG. a)). That is, in FIG. 11B, adjacent dots are arranged at the end of one pixel in the vertical and horizontal directions, but in FIG. 11C, since one dot corresponds to one pixel, variation can be suppressed. .
[0063]
As another method, an object moving table 2 that can adjust the distance between the spectroscopic camera 1 and the evaluation target T, that is, can move up and down may be used.
[0064]
FIG. 12 is a diagram for explaining that the color tone information Lab differs depending on the range of the visual field of interest V using the lightness L.
[0065]
As shown in FIG. 12A, when a part of the dot is applied to the end of the pixel, the color tone information Lab of each pixel fluctuates and the difference value becomes large. Conversely, as shown in (b), when the target visual field V and the dot do not overlap, the difference value becomes small.
[0066]
Therefore, when the variation width is reduced, it is possible to evaluate the color tone with one pixel as one field of view V, and it is not an average value but a measured value for each pixel, so that precise evaluation can be realized.
[0067]
When difference processing is performed on the color tone information Lab, the amount of variation is emphasized. In the case of FIG. 12A, the boundary between the laser marking portion and the non-marking portion is most emphasized by performing the difference process (see the difference value graphs W1 and W2 above). Further, if there is a change in the lightness L in the laser marking portion, the difference value shows a large value. Using this property, a laser marking portion sandwiched between places having a large difference value is extracted, and feedback control is performed so as to minimize the variation of the difference value in the laser marking portion, thereby determining the optimum field of view V. .
[0068]
Thus, by setting the optical system so as to minimize the fluctuation of the lightness L of the color tone information Lab, it is possible to determine the optimum field of view V, and as a result, it is possible to achieve more accurate evaluation.
[0069]
In addition, although it demonstrated by the lightness L here, when there is little change in lightness and there is a characteristic in chromaticity a or chromaticity b among the color tone information Lab, it is better to employ them.
[0070]
FIG. 13 is a diagram showing spectral intensity distribution information when the pattern pattern of the evaluation target T is imaged by the spectral camera.
[0071]
When the wavelength characteristics of the dot-like color elements constituting the design pattern are known, for example, when the periodicity of the pattern is best represented by a red color having a wavelength of 600 nm, the obtained spectral intensity distribution information is represented by the symbol B. When only the indicated wavelength of 600 nm is extracted and the spectral intensity with respect to the position is obtained, the waveform indicated by the symbol B1 is obtained. This waveform B1 has a clear resolution and a clear feature compared to the waveform indicated by the symbol C1 obtained by extracting and converting another wavelength indicated by the symbol C. Therefore, a specific wavelength component may be extracted in this way to detect the position and period of the symbol pattern, and the optimum field of view may be determined according to this position and period.
[0072]
Here, in the waveforms B1 and C1, the horizontal axis represents the measurement position, and the vertical axis represents the spectral intensity.
[0073]
【The invention's effect】
As can be understood from the above description, according to the color tone evaluation method according to claim 1 or the color tone evaluation apparatus according to claim 10, the color tone is evaluated for each visual field of interest in which dot-like color elements are uniformly included. Therefore, highly accurate color tone evaluation can be realized. In addition, since a predetermined calculation is performed on the spectral intensity distribution information decomposed into the color components by the spectral camera, it is easy to use the conversion formula for the color information (Lab) that can quantitatively represent the color tone. Can be calculated.
[0074]
In addition, if the average value of each of the marking part and the non-marking part is obtained by dividing the pixel of the marking part and the non-marking part in the field of interest, In spite of the poor color tone of the dot marking, the average value is not judged to be good as a result, and a highly accurate color tone evaluation can be performed.
[0075]
According to the method of claim 2, the color tone can be evaluated in the same manner as in claim 1 even in the case of dots by laser decoration.
[0076]
According to claim 3, since the angle can be provided in the arrangement relationship between the slit of the spectroscopic camera and the evaluation target, the proportion of dots in the field of interest can be appropriately dispersed and averaged, and as a result, It is possible to prevent variations in color tone due to misalignment of dots for each field of interest.
[0077]
According to the fourth aspect, since the color quality can be evaluated independently of the presence or absence of the design pattern, it is possible to prevent subtle defects from becoming difficult to detect by the entire averaging process, and to add and evaluate each of the plurality of parts collectively. The detection accuracy of the defect of the decoration part and the defect of the non-decoration part is improved, and it can be distinguished whether the defect is a decoration part defect or a non-decoration part defect.
[0078]
According to the fifth aspect, since the start end of the visual field of interest is set to the non-marking portion where the change in color tone is relatively stable, the measurement can be performed stably and the color tone evaluation with high accuracy can be performed.
[0079]
According to the sixth or thirteenth aspect, since the number of dot-like color elements included in the visual field of view and the arrangement relation can be adjusted, the evaluation accuracy can be improved by eliminating the uniformity of the number of dots and the lack of dots. Can be up.
[0080]
According to the seventh aspect of the present invention, it is possible to easily measure the difference between the color tone information and the measurement area, the dot, and the shift for each pixel. By performing this process as a feedback process, it is possible to determine an optimum field of view. If the field of interest obtained in this way is used, more accurate evaluation can be realized.
[0081]
According to the eighth or twelfth aspect, since a color camera is used in place of the spectroscopic camera, the calculation method is simple and the apparatus is inexpensive, so that a simple color tone evaluation can be realized.
[0082]
According to the ninth aspect, since the spectral intensity is measured by extracting a specific wavelength component of the design pattern that clearly shows the spectral intensity characteristics, it is appropriate to match the position of the main color component of the design pattern. It is possible to set a particular field of interest.
[0083]
According to the eleventh aspect, since the scanning position alignment means is provided, the inspection area can be easily changed, and further, the scanning position alignment means can be inclined at a predetermined angle. The effect of can be produced. Further, the scanning alignment means is configured to automatically perform alignment so that a high frequency component is not extracted from the color tone information for the calculated visual field of interest by the arithmetic processing means. The effect can be expected.
[Brief description of the drawings]
FIG. 1A is an object surface (evaluation target) on which a dot-shaped marking is applied by a laser, and FIG. 1B is an enlarged view of a part of the dot-shaped marking.
FIG. 2 is a diagram illustrating an example of a configuration of a color tone evaluation apparatus according to the present invention.
FIG. 3A is a diagram showing a main configuration of a spectroscopic camera that constitutes a part of the color tone evaluation apparatus of the present invention, and FIG. 3B is a graph for explaining the spectral intensity of a spectroscopic image.
FIG. 4 is a conversion formula for converting spectral intensity into color tone (Lab).
FIG. 5 is a list showing color tone (Lab) properties and numerical properties.
FIG. 6 is a diagram showing one aspect of spectral image measurement of an evaluation target by the color tone evaluation apparatus of the present invention.
7A is a diagram showing a part of an inspection region to be evaluated, and FIG. 7B is a graph showing the lightness of color tone information corresponding to each pixel of FIG.
FIG. 8 is a diagram showing the relationship between the periodicity of the symbol pattern and the set area.
FIG. 9 is a diagram illustrating an example of a symbol in which a cycle of a symbol pattern changes midway.
FIGS. 10A and 10B show a case where the visual field of interest is set parallel to the symbol pattern, and FIG. 10C shows a case where the angle of view is set.
FIGS. 11A and 11B are diagrams showing a spectroscopic camera equipped with a zoom lens, FIG. 11B is a view when the pattern pattern is the same magnification, and FIG. It is a figure which compares the relationship with a visual field.
FIG. 12 is a diagram for explaining that the color tone information varies depending on the range of the visual field of interest using lightness.
FIG. 13 is a diagram showing spectral intensity distribution information when a pattern pattern to be evaluated is captured by a spectral camera.
FIG. 14 is a diagram showing a relationship between dots constituting a design pattern to be evaluated and a measurement area.
[Explanation of symbols]
20. Color tone evaluation device
1 Spectroscopic camera
2 ... Object movement table
T: Object with a pattern pattern of dot-like color elements on the surface (object to be evaluated)
T1 ... Inspection area
V: Attention field of view
M: Marking part
S: Non-marking part
B ... Boundary part

Claims (13)

By scanning the spectroscopic camera on the surface of the object colored with a periodic design pattern including dot-like color elements, the image of the design pattern is captured, and the captured image is processed according to the following procedure. A color tone evaluation method characterized by determining whether the color tone of a design pattern is good 1) When an image having a design pattern is divided into image processing units, dot-like color elements are uniformly contained therein, A pattern composed of one or a plurality of periodic pattern patterns in which the positional relationship between the pattern and the image processing unit is synchronized is set as one field of view, and an image of the pattern pattern on the object surface captured as an inspection region through the spectroscopic camera is obtained. sequentially classified into the target field 2) this applying for each image processing unit in the examination region, a predetermined calculation process on the spectral intensity distribution information is decomposed into color components by the spectral camera 3) Sequentially convert the color information into color tone information 3) For each target visual field, sequentially calculate the average value of the color information, and each average value exceeds a predetermined upper limit value and lower limit value set in advance for each target visual field 4) In addition, it is determined whether the difference value between the average value calculated for each field of interest and the average value of the immediately preceding field of interest does not exceed a predetermined variation range. If this determination condition is satisfied with at least one of the above conditions 3) and 4) or a combination thereof as a determination condition, the design pattern applied to the object surface is good. Judged as bad. A spectroscopic camera is scanned on the surface of an object colored with a periodic pattern including dot-like color elements by laser decoration, and the image of the pattern on the surface of the object is captured. The color tone evaluation method is characterized in that the color tone of a design pattern is judged by performing arithmetic processing according to the following procedure: 1) When an image having a design pattern is divided into image processing units, dot shapes are included therein. A pattern composed of one or a plurality of periodic pattern patterns in which the color elements are uniformly included and the positional relationship between the pattern pattern and the image processing unit is synchronized is taken as one inspection field and taken as an inspection region through the spectroscopic camera. an image of the symbol pattern of the object surface to be, 2 are sequentially divided into the target field of view) for each image processing unit in the examination region is decomposed into color components by the spectral camera Sequential conversion into color tone information by applying predetermined calculation processing to the spectral intensity distribution information 3) Sequentially calculate the average value of the color tone information for each field of interest, and set each average value in advance for each field of interest 4) In addition, the difference value between the average value calculated for each of the fields of interest and the average value of the immediately preceding field of interest is a predetermined value . Determine whether or not the variation range is exceeded. 5) If the determination condition is satisfied using at least one of the above conditions 3) and 4) or a combination of these conditions, it is applied to the object surface. If the displayed symbol pattern is good, it is judged as bad if it is not. In claim 1 or 2,
The spectroscopic camera is scanned at a predetermined angle with respect to the pattern on the surface of the object, and an image of the pattern on the surface of the object is captured. A color tone evaluation method, characterized by sequentially dividing the field of interest into image processing units. In any one of Claims 1-3,
The average value is not calculated for the entire visual field of interest, but the average value is calculated separately for each image processing unit depending on the presence or absence of the pattern in the visual field of interest. A color tone evaluation method characterized by evaluating the color tone independently of the presence or absence of a design pattern for each field of interest in accordance with the procedure of 5-5. In any one of Claims 1-4,
3. The above-described 1) according to claim 1 or 2, wherein, in a series of color tone information calculated and converted for each image processing unit, a portion having the smallest color tone change amount is set as a start end of a visual field of interest. A color tone evaluation method characterized by evaluating a design pattern colored on the surface of an object in accordance with the procedure of ~ 5). In any one of Claims 1-5,
Color tone evaluation that makes it possible to adjust the arrangement of the dot-like color elements of the pattern pattern included in the field of interest by capturing the image of the object surface into the spectroscopic camera using optical image scaling means such as a zoom lens. Method. In any one of Claims 1-6,
A color tone evaluation method, further including a process of determining a position of a visual field of interest with respect to the symbol pattern by performing a difference process on the color tone information. In any one of Claims 1-7,
A color tone evaluation method, which uses a color camera instead of the spectral camera to capture an image of a design pattern on the surface of an object. In any one of Claims 1-8,
A color tone evaluation method, comprising: extracting a specific wavelength component of the symbol pattern, detecting a symbol pattern position, and determining a visual field of interest according to the symbol pattern position. A spectroscopic camera for scanning an object surface colored with a periodic design pattern including dot-like color elements and capturing an image of the design pattern on the surface;
An object surface design pattern color tone evaluation apparatus comprising an arithmetic processing means for processing an image captured by a spectroscopic camera in accordance with the following procedures 1) to 5): 1) An image having a design pattern as an image processing unit At the time of division, attention is paid to a pattern composed of one or a plurality of cycle pattern patterns in which dot-shaped color elements are evenly contained therein and the positional relationship between the pattern pattern and the image processing unit is synchronized. The image of the pattern pattern on the object surface taken as the field of view and taken as the inspection area through the spectroscopic camera is sequentially segmented into the field of interest 2) Spectral resolved into color components by the spectroscopic camera for each image processing unit in the inspection area Sequentially converted into color tone information by applying a predetermined calculation process to the intensity distribution information. 3) For each field of view, the average value of the color tone information is sequentially calculated, and each average value is Set for each order interest field, predetermined upper limit value, 4) also determines whether or not exceed the lower limit value, and the average value calculated for each of the target field, and the average value of the immediately preceding target field It is determined whether the difference value does not exceed a predetermined variation range. 5) When this determination condition is satisfied using at least one of the above conditions 3) and 4) or a combination thereof as a determination condition. Determines that the design pattern applied to the object surface is good, otherwise it is determined to be bad. In claim 10,
A scanning alignment means for moving at least one of the object surface colored with the spectral camera or the design pattern;
This scanning position alignment means is a color tone evaluation apparatus for a pattern on an object surface which is configured to automatically perform alignment so that the difference amount of color information for each image processing unit is reduced. In any one of Claims 10 and 11,
An apparatus for evaluating the color tone of a design pattern on an object surface, which uses a color camera instead of the spectral camera to capture an image of the design pattern on the object surface. In any one of Claims 10-12,
The spectroscopic camera or the color camera further includes a light image scaling unit that makes it possible to adjust the positional relationship of the dot-like color elements of the design pattern to be included in the field of interest.
This optical image scaling means is configured to automatically adjust the scaling ratio so that the arrangement of dot-shaped color elements of the pattern pattern included in the field of interest can be adjusted. apparatus.

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