JP2011232192A - Surface texture measurement device and surface texture measurement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a quantitative evaluation of degree of cloudiness when a surface of stainless steel plate, of mill roll, of metal mold or the like looks cloudy.SOLUTION: A surface texture measurement device 1 is made up so as to conduct following steps: a step to reflect a pattern displayed on a display 11 with a half mirror 13; a step to project the pattern on a surface of a measuring object 21 approximately vertically; a step to take a picture of the reflected pattern with an image pickup device 12 after transmitting the reflected pattern through the half mirror 13, and to implement data processing of image signals with a computer 3. In a surface texture measurement method, the surface texture measurement device 1 achieves a measurement condition which highlights an influence of irregular reflection of surrounding light on a pattern image partially reflecting within a range of pattern projection area on the surface of the measuring object 21, based on a mode of pattern setting, and it quantitatively evaluates a degree of cloudiness on the surface of the measuring object due to the influence of irregular reflection of light.

Description

  In the present invention, the surface of a product such as a stainless steel plate, which is required to have a smooth surface close to a mirror surface, or a processing machine or processing tool such as a rolling roll or a die that affects the surface properties of the product appears cloudy. In this case, the present invention relates to a surface texture measuring device and a surface texture measuring method for quantitatively evaluating the degree of white turbidity as surface texture.

  As a device for measuring the surface property of a smooth surface close to a mirror surface, a surface roughness meter (abbreviated as a roughness meter for short) that measures surface roughness (roughness of fine irregularities) with a stylus type. In addition, a specular gloss meter (also referred to as a gloss meter for short) that measures glossiness with the amount of light received by regular reflection (specular reflection) has been used.

  There is also a device that measures the surface roughness and glossiness by taking a reflected image instead of measuring only the amount of received light.For example, a monochrome pattern of light is projected obliquely at a predetermined angle with respect to the measurement target surface, and the same angle. It is conventionally known to measure the surface properties in a non-contact manner by reflecting the pattern back to the opposite side (regular reflection), taking a pattern reflection image with a camera, and processing the image signal with a computer. (For example, refer to Patent Documents 1 and 2.)

  In addition, the applicant plots the luminance distribution of the captured pattern reflection image (graphs a part of the pattern), obtains the standard deviation of the luminance waveform (variation in luminance from the average luminance), and calculates the standard deviation based on the standard deviation. Developed a surface texture measurement method and device for measuring roughness, surface reflectance, etc., and also calculated the relative value of the standard deviation of the brightness value of the pattern reflection image with the standard deviation used as a reference in the case of a mirror surface. ”, And the fact that the rectangular waveform of the luminance waveform is narrowed and the edges are sagged with the specularity, which is the relative value of the standard deviation, makes it possible to map the sample surface (the pattern is accurate). Specularity evaluation method that quantitatively evaluates surface properties such as surface roughness and glossiness caused by minute surface irregularities by adding other information such as reflectance And run it It has developed a device for (e.g., see Patent Documents 3 and 4.).

JP-A-61-75236 JP 2006-84452 A JP 2001-99632 A JP 2007-155709 A

  The surface of a stainless steel plate or the like may appear cloudy with a streak-like white line on visual inspection even if there is almost no difference from the mirror surface when measured with a surface roughness meter or specular gloss meter. However, depending on how you look at it, the cloudiness may stand out, or you may not be able to see it at all if you change the angle slightly. And when you look at the cloudy surface with a microscope, you can see that there are scratches. The surface roughness meter and specular gloss meter do not provide numerical information that can be obtained visually.

  In a stylus-type surface roughness meter (roughness meter), the size of the probe tip is the limit of measurement resolution, and it is difficult to identify scratches that cause white turbidity with a roughness curve. In the case of a clean mirror surface without scratches, the roughness curve is almost flat. On the other hand, when there is a scratch that causes white turbidity, the roughness curve is flat as a whole, and a minute portion partially protrudes. However, even if it partially protrudes in this way, when viewed from the roughness curve, most of it is flat, and Ra (arithmetic average roughness) is hardly affected.

  In the specular gloss meter, even when there is a flaw and it appears cloudy, the flaw is a very small part of the surface, has little effect on the amount of received light, and there is almost no difference in measured values. The JIS specular gloss measurement method uses a measuring device that measures specular gloss and reflectance, and measures the reflected light flux (energy). However, the influence of irregular reflection is extremely small in terms of energy, and light is reflected almost without being affected by scratches as energy, and thus hardly affects.

  Further, even in the specularity evaluation apparatus developed by the present applicant, white turbidity does not appear as a clear numerical value. The specularity evaluation device quantitatively evaluates the surface properties such as roughness and glossiness of the sample surface based on the reflection of the pattern reflected image reflected on the sample surface (image quality). Therefore, the luminance waveform of the pattern reflection image hardly shows a difference from the case where there is no scratch, and the cloudiness cannot be quantitatively evaluated.

  Thus, when the surface of a stainless steel plate or the like appears clouded when viewed visually, the conventional device or method cannot quantitatively evaluate the cloudiness. For this reason, it is only possible to visually check whether it is cloudy, but depending on how you see it, the cloudiness may be noticeable, or if you change the angle slightly, it may not be visible at all, and people may see it differently. Therefore, an objective evaluation was not possible.

  By the way, in the specularity evaluation apparatus, the focus of the camera is matched to the pattern reflection image. In this case, instead of looking at the sample surface, the sample surface is treated as a mirror, a pattern is copied on the sample surface, and the image of the reflected pattern is in focus. In contrast, when a human visually observes the surface of a sample such as a stainless steel plate and sees white turbidity, the eye is focused on the white turbid sample surface. When looking at a sample on the surface of the sample, the eyes are focused on the reflected face, and at that time, the cloudy part of the sample surface is not clearly visible. However, humans can easily change the focus of their eyes, and even if they are capturing a face, if they are concerned that the sample surface is cloudy, they will immediately focus on the cloudy sample surface. However, the specularity evaluation apparatus focuses on the pattern reflection image, and does not focus on the sample surface as viewed visually. Therefore, the cloudiness cannot be clearly seen.

  Even in the case of the specularity evaluation apparatus, it is considered that the white turbidity can be evaluated by a measuring instrument if the surface of the sample is focused as in the case of visual observation. However, the specularity evaluation apparatus originally evaluates the image clarity, and it is necessary to focus on the pattern reflection image. In order to use this for the evaluation of the cloudiness of the sample surface, Must be adjustable, not fixed. Then, the apparatus becomes too large as a measuring instrument, and since the focus is not fixed, a troublesome operation is required for focusing, and a decrease in measurement accuracy due to an error in focusing becomes inevitable. Therefore, a commercially available measuring instrument is not practical unless the focus position is fixed. Also, if a separate measuring instrument with only the focus setting changed is prepared and used separately, the burden will increase in terms of space and cost.

  The present invention solves such a problem, and the surface of a product such as a stainless steel plate, which is required to have a smooth surface close to a mirror surface, and a processing machine such as a rolling roll and a die that influence the surface properties of the product. Alternatively, when the surface of a processing tool appears cloudy, the degree of cloudiness can be quantitatively evaluated, and the apparatus does not become overly large and does not require troublesome operations. The purpose is to provide.

  The surface texture measuring apparatus of the present invention forms a pattern showing a two-dimensional distribution shape of optical brightness with a display that can be controlled by a computer, reflects the pattern with a half mirror, and projects the pattern substantially perpendicularly onto the surface to be measured. A projection optical system and an imaging optical system that takes a pattern reflected by the measurement target surface and reflected by the measurement target surface through the half mirror and captures an image from the direction substantially perpendicular to the measurement target surface. A surface texture measuring device that measures the surface texture of a measurement target surface by processing the video signal obtained by the element with a computer, to a pattern image reflected in a part of the pattern projection area on the measurement target surface Pattern setting means for realizing the measurement conditions that emphasize the influence of the irregular reflection of light from around the pattern according to the pattern setting mode. Based on the video signal obtained by emphasizing measurement conditions Hibiki, the degree of influence of light irregularly reflected measurement, by the degree of influence, and evaluating the turbidity degree by irregular reflection of light of the measurement target surface.

  In this surface texture measuring device, the pattern setting means projects the first pattern setting for projecting an optical bright / dark pattern over the entire area of the pattern projection area, and projects the optical bright / dark pattern over a partial area of the pattern projection area. Then, it is possible to set the second pattern to darken the surroundings, and by comparing the video signal obtained by the first pattern setting with the video signal obtained by the second pattern setting, the degree of influence of irregular reflection of light can be set. Measurement may be performed to evaluate the degree of white turbidity due to irregular reflection of light on the surface to be measured.

  In addition, this surface texture measuring device can set a pattern that darkens a part of the pattern projection area and brightens the surroundings by the pattern setting means, and the degree of influence of irregular reflection of light by the video signal obtained by this pattern setting And the degree of white turbidity due to irregular reflection of light on the surface to be measured may be evaluated.

  The surface texture measuring device may be provided with a brightness value calculating means for processing the video signal to obtain the brightness value of the pattern image, and measure the degree of influence of irregular reflection of light based on the brightness value.

  In the surface texture measuring method of the present invention, a pattern showing a two-dimensional optical bright / dark distribution shape is formed by a display that can be controlled by a computer, and the pattern is reflected by a half mirror to be substantially perpendicular to the surface to be measured. The pattern reflected on the surface to be measured and reflected by the surface to be measured is transmitted through the half mirror, photographed with an image sensor from a direction substantially perpendicular to the surface to be measured, and the video signal obtained by the image sensor is processed with a computer. Is a surface property measurement method for measuring the surface property of a measurement target surface by a measurement condition that emphasizes the influence of irregular reflection of light from the surroundings on a pattern image reflected in a partial area of the pattern projection area on the measurement target surface Is realized by the pattern setting mode, and the degree of influence of diffused light reflection is measured based on video signals obtained under measurement conditions that emphasize the influence of diffused light reflection. And, by the degree of influence, and evaluating the turbidity degree by irregular reflection of light of the measurement target surface.

  In this surface texture measuring method, the video signal is acquired with a first pattern setting for projecting an optical bright / dark pattern over the entire range of the pattern projection area, and the optical brightness / darkness is only applied to a partial range of the pattern projection area. The video signal is acquired with a second pattern setting in which a pattern is projected and the surroundings are darkened, and the video signal obtained with the first pattern setting is compared with the video signal obtained with the second pattern setting. The degree of influence of light irregular reflection may be measured, and the degree of white turbidity due to light irregular reflection on the measurement target surface may be evaluated.

  In addition, this surface texture measurement method acquires a video signal with a pattern setting that darkens a part of the pattern projection area and brightens the surroundings, and measures the influence of diffuse reflection of light using the video signal obtained by this pattern setting. Then, the degree of white turbidity due to irregular reflection of light on the surface to be measured may be evaluated.

  This surface texture measuring method may be a method of processing the video signal to obtain a luminance value of the pattern image and measuring the influence degree of the irregular reflection of the light based on the luminance value.

  The display for forming the pattern may be a display other than a liquid crystal display, such as plasma, organic / inorganic EL, or the like.

  When the surface is visually observed, the surface appears cloudy because of the presence of streak-like scratches that are unusual irregularities with a large irregularity angle compared to normal surface irregularities that can be measured with a surface roughness meter. If there is a scratch with such a large unevenness angle, the main reason is that the light that enters from the surroundings is reflected in a direction that is not reachable in the case of normal surface unevenness, diffusely reflected and scattered at the scratched part. It is influenced by the fact that it enters the eyes as light. Therefore, it is basically possible to measure under measurement conditions that emphasize the influence of irregular reflection of light entering from the surroundings, using the measurement method of the specularity evaluation device that measures the surface properties by processing the pattern reflection image. By doing so, it is possible to quantitatively evaluate the degree of white turbidity due to the influence of irregular reflection of light from the surroundings. The present invention has been made based on these findings.

  In the present invention, a pattern showing a two-dimensional distribution shape of optical brightness is formed by a display such as liquid crystal that can be controlled by a computer. Then, the pattern formed by the display is reflected by the half mirror and projected onto the surface to be measured approximately perpendicularly, and the reflected pattern is transmitted through the half mirror and transmitted from the direction substantially perpendicular to the surface to be measured by the image sensor. The pattern reflection image is taken with the focus of the image sensor, and the video signal is processed by a computer. In that case, the measurement conditions which emphasize the influence of the irregular reflection of the light from the circumference | surroundings on the pattern image reflected in the partial range of the pattern projection area | region on a measurement object surface are implement | achieved by the aspect of pattern setting. Then, based on the video signal obtained under the measurement condition that emphasizes the influence of the irregular reflection of light, for example, the luminance value of the pattern image is obtained by data processing of the video signal, and the influence degree of the irregular reflection of the light based on the luminance value And the degree of white turbidity due to irregular reflection of light on the measurement target surface is evaluated based on the degree of influence.

  The pattern setting mode for realizing the measurement condition that emphasizes the influence of irregular reflection of light is, for example, the first pattern setting for projecting an optical bright / dark pattern (for example, a black and white striped pattern) over the entire pattern projection area. The second pattern setting is switched so that an optical bright / dark pattern is projected only in a part of the pattern projection area and the surrounding area is darkened. The degree of influence of irregular reflection of light is measured by comparing the image signals, and the degree of white turbidity due to irregular reflection of light on the measurement target surface is evaluated. In this case, the pattern settings can be switched by a computer that displays an optical bright / dark pattern on the entire display surface (a setting that makes the light source wider), and an optical bright / dark pattern that is displayed only at the center of the display. This can be done easily by switching the setting to darken the whole (setting to narrow the light source). When the entire surface pattern is set (shown on the entire surface of the display), an optical bright / dark pattern is projected over a wide area on the measurement target surface, and a partial pattern (the pattern is projected only at the center of the display and the surrounding area is displayed). When the part is set to be completely dark), an optical bright / dark pattern is projected only on a limited narrow area on the measurement target surface.

  Since the light from the display has an opening angle, not only light enters the pattern projection area on the measurement target surface at the set projection angle, but also light from the surroundings. come. If the surface to be measured is not damaged, the light that enters at the set projection angle is specularly reflected and enters the image sensor, but the light from the surroundings is reflected in a direction that does not reach the image sensor. And if there is a scratch that causes white turbidity on the measurement target surface, in the case of a full pattern, since the light source is wide, each part of the area to be measured (part of the pattern projection area) from around There is a lot of incoming light, and the light that enters from the surroundings is irregularly reflected at the scratched part and becomes scattered light, and part of it reaches the image sensor. For this reason, the video signal obtained by photographing is greatly influenced by irregular reflection of light entering from the surroundings. On the other hand, in the case of a partial pattern, since the light source is narrow and light hardly enters from the surroundings, the influence of irregular reflection of the light from the surroundings becomes small. Therefore, the image signal in the first pattern setting for projecting the optical bright / dark pattern to the entire range of the pattern projection area and the optical bright / dark pattern are projected only to a partial range of the pattern projection area to darken the surroundings. By comparing the video signal with the second pattern setting, it is possible to quantitatively evaluate the degree of white turbidity due to the influence of diffuse reflection of light from the surroundings.

  In addition, the pattern setting mode that realizes the measurement condition that emphasizes the influence of irregular reflection of light is a pattern that darkens a part of the pattern projection area and brightens the surroundings (for example, there is only a black part at the center of the display image). In this case, the degree of influence of irregular reflection of light is measured by the video signal obtained by this pattern setting, and the degree of white turbidity due to irregular reflection of light on the measurement target surface is evaluated. This pattern setting can be easily performed by a computer.

  In this case as well, since the light from the display has an opening angle, not only does the light enter the pattern projection area on the measurement target surface at the set projection angle, but also from the surroundings. Light enters. However, the pattern in this case is a pattern that darkens a part of the pattern projection area and brightens the surroundings (a dot pattern with only a black part at the center of the display image). Light does not enter at the set projection angle, and light mainly enters from the surroundings. If there is no scratch on the surface to be measured, the light from the surroundings will be reflected in a direction that does not reach the image sensor, but if there is a scratch on the surface to be measured causing white turbidity, the light entering from the surroundings will be reflected. It is irregularly reflected at the scratched part and becomes scattered light, and part of it reaches the image sensor. Therefore, the video signal obtained by photographing is mainly influenced by the irregular reflection of light entering from the surroundings. Therefore, based on the video signal obtained by setting a pattern that darkens the partial area of the pattern projection area and brightens the surrounding area, it is a quantitative measure of the degree of white turbidity caused by the diffuse reflection of light from the surroundings. Can be evaluated.

  In the present invention, the light of the pattern is reflected by the half mirror and projected on the measurement target surface substantially perpendicularly, and the pattern reflection image is transmitted through the half mirror and photographed by the image sensor from the direction substantially perpendicular to the measurement target surface. As a result, the characteristics of each video signal when the measurement target surface with scratches that cause white turbidity is measured with the full pattern setting and with the partial pattern setting are emphasized. Therefore, it becomes easy to measure the influence of irregular reflection due to scratches, and the degree of cloudiness can be easily evaluated with high accuracy.

  If the pattern is projected obliquely onto the surface to be measured and photographed from the opposite side, a video signal that emphasizes the influence of irregular reflection of light cannot be obtained even if there is a scratch that causes white turbidity. However, when a pattern is projected substantially perpendicularly on the measurement target surface, a video signal in which the influence of light irregular reflection is emphasized can be obtained in the case of the entire pattern and the case of the partial pattern. This is related to the nature of the wound.

  In the case of a scratch with a large uneven angle that causes white turbidity on the surface to be measured, it is more likely that light from the surroundings enters the direction relatively close to the top rather than entering obliquely from the side. The probability of reaching the image sensor when reflected by the inclined surface increases. In this case, the angle of the inclined surface of the scratch (unevenness angle) tends to satisfy such a condition in relation to the incident and reflection directions. When a pattern is projected substantially perpendicularly to the measurement target surface and the reflected pattern image is photographed from a direction substantially perpendicular to the measurement target surface, the light entering from the surroundings enters obliquely from the side. Rather, light enters from a direction that is relatively close to the top, and light reflected from the inclined surface of the scratch is likely to enter the image sensor. For this reason, when light is irregularly reflected, the effect is likely to appear in the video signal, and the effect of irregular reflection can be quantitatively evaluated by adjusting the conditions for emphasizing it. On the other hand, if the pattern is projected obliquely to the surface to be measured and photographed from the opposite side, for example, the relationship between the angle of the scratched surface and the incidence and reflection direction is because the light reflected by the scratched surface reaches the image sensor. It is difficult to meet the conditions. For this reason, the influence of irregular reflection of light hardly appears and measurement is difficult.

  According to the present invention, the surface of a product such as a stainless steel plate that is required to have a smooth surface close to a mirror surface, or the surface of a processing machine or processing tool such as a rolling roll or a mold that affects the surface properties of the product. When it appears cloudy, the degree of cloudiness can be accurately and quantitatively evaluated without making the apparatus large and troublesome operation.

It is the schematic of the surface property measuring system which concerns on embodiment of this invention. FIG. 4A shows a first example of pattern setting, where FIG. 5A is a diagram showing a display screen when setting a full pattern, and FIG. 5B is a diagram showing a display screen when setting a partial pattern. FIGS. 2A and 2B show a second example of pattern setting, in which FIG. 3A is a diagram showing a display screen when setting a point pattern, and FIG. It is a cross-sectional schematic diagram which shows the relationship between the incident direction of the light from the circumference | surroundings with respect to the damage | wound of a measuring object surface, and a reflection direction. It is a graph explaining the aspect of the luminance distribution which changes at the time of the whole surface pattern setting and the partial pattern setting. It is a photograph of the sample in the Example of this invention. The example of the luminance distribution in the sample surface in the Example of this invention is shown, (a) is a graph of the luminance distribution in the surface without a flaw, (b) is the luminance in the surface with a flaw by 1500th sandpaper. A distribution graph, (c), is a graph of a luminance distribution on a surface having scratches due to the 1200th sandpaper.

  FIG. 1 shows an example of a surface texture measuring system according to an embodiment of the present invention. In the figure, 1 is a surface texture measuring device, 2 is an object to be measured, and 3 is a computer.

  The surface texture measuring device 1 includes a pattern forming display 11 that can be controlled by a computer 3, a photographing device 12 that captures a reflection image of the pattern, and a half mirror 13. The surface texture measuring device 1 has a two-dimensional distribution of optical brightness. For example, a black and white striped pattern or a dot-like pattern indicating the shape is formed on the display 11, the pattern is reflected by the half mirror 13 and projected substantially perpendicularly onto the measurement target surface 21, and the projection optical system projects the pattern. And an imaging optical system that captures the reflected image of the pattern reflected by the measurement target surface 21 through the half mirror 13 and captures the image with the imaging element (imaging device 12) from a direction substantially perpendicular to the measurement target surface 21. A pattern indicating a two-dimensional distribution pattern of optical brightness is formed on the display 11, and the pattern itself becomes a light source and is substantially flat on the measurement target surface 21 of the measurement target 2. The pattern reflected by the measurement target surface 21 is reflected by the half mirror 13, reflected by the half mirror 13, projected substantially perpendicular to the measurement target surface 21 (projected at an angle of 90 degrees in the figure), The imaging device 12 is configured to transmit the image through the mirror 13.

  The display 11 is a liquid crystal display, for example. In addition, a display such as plasma and organic / inorganic EL may be used.

  The pattern formed by the display 11 can be freely set by operating the computer 3. For example, in the case of a black and white striped pattern, the pattern is projected on the entire screen of the display 11 as shown in FIG. In addition, as shown in FIG. 2B, the pattern is projected only at the center of the screen of the display 11, and the entire periphery is completely darkened to narrow the light source. Some patterns can be set, and these settings can be easily switched. Also, as shown in FIG. 3, it is possible to set a point pattern in which there is only a black portion at the center of the image (which is a circle in the example of the figure, but may have a shape other than a circle). Setting and switching of the shape, size, etc. of the part can be easily performed.

  The imaging device 12 includes an area image sensor such as a CCD, CMOS, or digital camera as an image sensor. The focus of the imaging device is adjusted to the position of the virtual image plane 4 where the pattern reflected through the measurement target surface 21 connects the images. The focusing is simply performed by adjusting the height of the surface texture measuring device 1 itself and / or the height of the table on which the measurement object 2 is placed while the focal length of the image sensor is fixed. be able to.

  In the surface texture measuring apparatus 1, as shown in FIG. 1, the measurement object surface 21 of the measurement object 2 is arranged so as to be perpendicular to the screen of the display 11 (in the example shown, the display 11 is in the vertical direction). In this arrangement, the measurement target surface 21 is arranged in the horizontal direction.) The pattern (image) formed on the display 11 is irradiated in a direction substantially parallel to the measurement target surface 21, reflected by the half mirror 13, and projected onto the measurement target surface 21 substantially perpendicularly. In the example of the figure, the pattern is irradiated in a direction (horizontal direction) parallel to the measurement target surface 21 of the measurement target 2. The half mirror 13 is disposed at an angle of 45 degrees with respect to the horizontal direction, and the pattern reflected by the half mirror 13 is projected onto the measurement target surface 21 at an angle of 90 degrees. At this time, the reflected image of the pattern projected on the measurement target surface 21 appears perpendicular to the screen of the display 11. The pattern reflection image is photographed by the image sensor of the photographing device 12 through the half mirror 13. Then, the obtained video signal is processed by the computer 3 to measure the surface roughness and the like of the measurement target surface 21.

  For example, a stripe pattern as shown in FIG. Then, the pattern is reflected by the half mirror 13 and projected onto the measurement target surface 21, and the reflected pattern is transmitted through the half mirror 13 and photographed by the photographing device 12 (imaging device). Processing and plotting the luminance distribution of the captured pattern reflection image (graphing part of the pattern) to obtain the standard deviation of luminance value (variation of luminance from the average luminance), and based on the standard deviation, the surface roughness Measure. There is a relatively linear correlation between the standard deviation of the luminance value and the standard deviation of the surface inclination angle distribution due to surface irregularities, and the surface roughness can be evaluated by the standard deviation of the luminance distribution. Also, the specularity that is a relative value of the standard deviation of the luminance distribution of the pattern reflection image to the standard deviation as a reference is calculated (for example, the standard deviation of the reference sample is assumed to be a specularity of 1000, and the relative measurement target surface The surface roughness due to surface irregularities is evaluated by evaluating the image clarity of the sample surface (whether the pattern is accurately reflected) and adding other information such as reflectance. It is also possible to comprehensively and quantitatively evaluate surface properties such as sheath and glossiness.

  Further, in this surface texture measuring device 1, by adjusting the setting mode of the pattern formed by the display 11, the light from the surroundings to the pattern image reflected in a partial range of the pattern projection area on the measurement target surface 21. A measurement condition that emphasizes the influence of diffuse reflection can be realized. Based on the video signal obtained under the measurement condition that emphasizes the influence of diffuse reflection of light, for example, the luminance value of the pattern image is obtained by processing the video signal. The degree of influence of light irregular reflection is measured based on the luminance value, and the degree of white turbidity due to light irregular reflection on the measurement target surface can be evaluated based on the degree of influence.

  For example, as shown in FIG. 2A, a measurement condition for emphasizing the influence of irregular reflection of light is a pattern on the entire surface of the display 11 that is projected on the entire surface of the display 11 to widen the light source. A first pattern setting for projecting an optical bright / dark pattern (in the figure, a black and white striped pattern, but not limited to this) in the entire pattern projection area, and FIG. As shown in the figure, a pattern is projected only at the center of the screen of the display 11, and a peripheral pattern is projected as an optical bright / dark pattern only in a partial area of the pattern projection area as a partial pattern that darkens the whole and narrows the light source. Then, it can be realized by switching to the second pattern setting for making the surroundings dark.

  The measurement conditions for emphasizing the influence of irregular reflection of light are, for example, as a point pattern in which there is only a black portion at the center of the display image, and a part of the pattern projection area on the measurement target surface 21 is darkened and the surroundings are brightened. This can also be realized.

  Since the light from the display 11 has an opening angle, as shown in FIG. 4, the light a just enters the respective parts of the measurement target surface 21 substantially vertically (set projection angle). There is also light b from around. Then, if the pattern formed by the display 11 is a full pattern as shown in FIG. 2 (a), the light source area is enlarged. If there is irregular reflection, each part (partial range) of the pattern projection area The influence of irregular reflection of light from the surroundings becomes large. On the other hand, when a partial pattern as shown in FIG. 2B is used, the light source region is reduced, so that light entering from the surroundings is reduced and the influence of irregular reflection is reduced. That is, if there is a flaw 22 that causes white turbidity on the measurement target surface 21, in the case of the entire surface pattern, since the light source is wide, there is a lot of light b entering from the surroundings, and light b entering from the surroundings. However, the light is irregularly reflected at the portion of the scratch 22 and becomes scattered light, and a part of the light reaches the image sensor. For this reason, the video signal obtained by photographing is greatly influenced by irregular reflection of light entering from the surroundings. On the other hand, in the case of a partial pattern, since the light source is narrow and almost no light b enters from the surroundings, the influence of irregular reflection of light from the surroundings is small. Therefore, the image signal in the first pattern setting for projecting the optical bright / dark pattern to the entire range of the pattern projection area and the optical bright / dark pattern are projected only to a partial range of the pattern projection area to darken the surroundings. By comparing with the video signal in the second pattern setting, the influence of diffuse reflection of light from the surroundings can be emphasized, and quantitative evaluation of the degree of white turbidity due to the influence of diffuse reflection It can be carried out.

  Further, as shown in FIG. 3, the pattern formed by the display 11 is a dot pattern having only a black portion at the center of the image, and a part of the pattern projection area on the measurement target surface 21 is darkened and the surroundings are brightened. When set, light does not enter the region to be measured (part of the pattern projection region) at the set projection angle, and light mainly enters from the surroundings. If the measurement target surface 21 is not damaged, light from the surroundings is reflected in a direction that does not reach the image sensor, but if the measurement target surface 21 has a scratch that causes white turbidity, it enters from the periphery. The light is diffusely reflected at the scratched part and becomes scattered light, and part of the light reaches the image sensor. Therefore, the video signal obtained by photographing is mainly due to the influence of irregular reflection of light entering from the surroundings. Therefore, based on the video signal obtained by setting a pattern that darkens the partial area of the pattern projection area and brightens the surrounding area, it is a quantitative measure of the degree of white turbidity caused by the diffuse reflection of light from the surroundings. Can be evaluated.

  Then, the surface texture measuring apparatus 1 projects the pattern light onto the measurement target surface 21 through the half mirror 13 and transmits the pattern reflection image through the half mirror 13 so as to be substantially perpendicular to the measurement target surface 21. By photographing with the photographing device 12 (imaging device) from various directions, the measurement target surface 21 with the scratch 22 that causes white turbidity is measured with the setting of the entire pattern and when measured with the setting of the partial pattern. Thus, the degree of influence of irregular reflection of each video signal can be made to stand out, and the degree of influence of diffuse reflection in the case of a point pattern can be made to stand out. Therefore, measurement of the degree of influence of irregular reflection is easy, evaluation of the degree of white turbidity is easy, and accurate measurement and evaluation can be performed.

  When the luminance distribution of the pattern reflection image is plotted from each video signal with the setting of the entire surface pattern as shown in FIG. 2A and the setting of the partial pattern as shown in FIG. A luminance distribution as shown in FIG. 5 is obtained. In FIG. 5, the thin line is the waveform of the luminance distribution when the entire surface pattern is used, and the thick line is the waveform of the luminance distribution when the partial pattern is used. If there is a flaw that causes white turbidity on the measurement target surface 21, the luminance value is shifted in the direction of decreasing the entire pattern as compared with the entire pattern. By obtaining this shift amount by the difference between the average values of the luminance values, the degree of cloudiness can be quantitatively evaluated.

  Further, in the point pattern setting as shown in FIG. 3, if there is a flaw that causes white turbidity on the measurement target surface 21, the luminance value measured within a certain range of the black portion at the center of the image is the standard mirror surface. The luminance value is higher than the luminance value in the case, and the difference is noticeable. By comparing the average values of the luminance values, quantitative evaluation of the degree of white turbidity can be performed more easily.

  In this way, when the surface of a product such as a stainless steel plate, which is required to have a smooth surface close to a mirror surface, or a processing machine or processing tool such as a rolling roll or mold that affects the surface properties of the product appears cloudy. The degree of white turbidity can be accurately and quantitatively evaluated without making the apparatus large and troublesome.

  In addition, this invention is not limited to the said embodiment, The measurement conditions which emphasize the influence of the irregular reflection of the light from the circumference | surroundings to the pattern image reflected in the partial range of the pattern projection area | region on a measurement object surface are set. The embodiment can be variously changed without departing from the measurement principle of the present invention, which is realized by the pattern setting mode and measures the degree of white turbidity of the measurement target surface by the degree of influence of diffused reflection of light. is there. The mode of pattern setting is not limited to the switching of black and white striped patterns and the use of point patterns described in the above embodiment.

  FIG. 6 shows a photograph of a sample in which a polished surface of a stainless steel plate is partially scratched with a 1200th sandpaper and a 1500th sandpaper.

  As shown in FIG. 6, on the surface of the sample, the unscratched part (A part) looks beautiful (small cloudiness), and the part (B part) scratched with 1500 sand paper appears cloudy (white turbidity). Middle), the part (C part) scratched with coarse sandpaper (No. 1200) appears more cloudy (large cloudiness).

  Even if there are scratches such as B and C in FIG. 6 that appear to be cloudy, the enlarged parts are mostly smooth and clean, and the scratches are only a small part. It is. Such a scratch cannot be clearly identified even when measured with a surface roughness meter or a specular gloss meter. In the surface roughness meter, the effect of the probe tip size appears in the roughness curve, so the measurement resolution is limited, and it is difficult to identify scratches that cause white turbidity. Further, even in the specular gloss meter, scratches are a very small part of the surface and hardly affect the amount of received light, so there is almost no difference in measured values.

  Therefore, the surface texture measuring apparatus 1 shown in FIG. 1 is used, a liquid crystal display is used for the display 11, and the pattern projected on the liquid crystal display is set to the full surface pattern shown in FIG. In the setting of the partial pattern shown in (b) of FIG. 6 (a circle with a diameter of 100 pixels in the center is a black and white stripe and the surrounding is true black), the A part, the B part, and the C part are measured, and the pattern is obtained from each video signal The luminance distribution of the reflected image was plotted.

  The brightness distribution thus obtained is shown in FIG. (A) Luminance distribution on the non-scratched surface (A part), (b) Luminance distribution on the scratched surface (B part) by 1500 sandpaper, (c) Scratch by 1200 sandpaper It is a luminance distribution in a certain surface (C section). In FIG. 7, the thin line is the waveform of the luminance distribution when the entire surface pattern is used, and the thick line is the waveform of the luminance distribution when the partial pattern is used. In either case, the horizontal axis represents pixels (that is, measurement positions), and the vertical axis represents luminance values (indicated by standard deviation).

  As shown in FIG. 7A, on the sample surface without scratch (A part), the luminance waveforms are almost the same in the case of the full pattern and the case of the partial pattern. However, as shown in FIG. 7 (b), on the surface with scratches due to the 1500th sandpaper (B section), the luminance waveform in the case of the partial pattern is generally lower than the luminance waveform in the case of the entire pattern. Shifted to the luminance side. In addition, on the surface (C portion) having a scratch due to the coarse sandpaper of No. 1200, as shown in FIG. 7C, the luminance waveform in the case of a partial pattern as compared to the luminance waveform in the case of the entire pattern. Is larger and shifted to the lower luminance side as a whole. The shift amount was determined by the difference between the average values of luminance values (standard deviation).

  The difference between the average values of the luminance values thus obtained is taken as the measured values of the A part, the B part, and the C part, and Table 1 shows the measured values and the comparative values of the A part standard.

  Each measurement result (difference in the average value of the luminance values) of A part, B part and C part shown in Table 1 quantitatively shows the difference (degree of white turbidity) that appears white due to irregular reflection of light due to scratches. is there.

  Further, the surface texture measuring apparatus 1 shown in FIG. 1 is used, a liquid crystal display is used for the display 11, and a pattern projected on the liquid crystal display is a dot pattern having a black circle at the center of the image as shown in FIG. As the setting, the same sample as in Example 1 was measured, and the luminance value of the pattern reflection image was obtained from the video signals obtained in the A part, the B part, and the C part.

  In this case, on the sample surface without scratches (A portion), the pattern reflection image has a low luminance value at the center black portion because there is little influence of irregular reflection of light, but the scratched surfaces (B portion, C portion) ), The rougher the flaw, the higher the luminance value of the black part due to the effect of irregular reflection.

  In FIG. 3 (b), the average value of the luminance values within the range indicated by the black squares is the measured values of the A part, the B part, and the C part, and the measured values and the comparative values of the A part reference are shown. It is shown in 2.

  Each measurement result (average value of luminance values) of A part, B part, and C part shown in Table 2 quantitatively shows a difference (degree of white turbidity) that appears white due to irregular reflection of light due to scratches.

  When Table 1 and Table 2 are compared, in the case of a sample with a high degree of white turbidity, setting a point pattern as shown in FIG. 3 rather than measuring the degree of whiteness by comparing the case of a black and white full pattern and the case of a partial pattern. It can be seen that the sensitivity is higher when measured by the luminance value measured in (1).

DESCRIPTION OF SYMBOLS 1 Surface property measuring device 11 Display 12 Image pick-up device 13 Half mirror 2 Measuring object 21 Measuring object surface 22 Scratch 3 Computer 4 Virtual image surface

Claims (8)

A projection optical system that forms a pattern showing a two-dimensional optical bright / dark distribution shape on a display that can be controlled by a computer, reflects the pattern with a half mirror, and projects it almost perpendicularly to the measurement target surface, and a projection optical system. The image signal obtained by the imaging device, which includes the imaging optical system that captures the pattern reflected and reflected by the measurement target surface through the half mirror and captures the image from the direction substantially perpendicular to the measurement target surface. A surface texture measuring device for measuring the surface texture of the surface to be measured by processing data with a computer,
A pattern setting unit that realizes a measurement condition that emphasizes the influence of irregular reflection of light from around a pattern image reflected in a partial range of a pattern projection area on the measurement target surface by the pattern setting mode;
The degree of influence of the irregular reflection of light is measured based on a video signal obtained under measurement conditions that emphasize the influence of the irregular reflection of light, and the degree of white turbidity due to the irregular reflection of light on the measurement target surface is evaluated based on the degree of influence. A surface texture measuring apparatus characterized by the above. The pattern setting means projects a first pattern setting for projecting an optical bright / dark pattern over the entire range of the pattern projection area, and projects an optical bright / dark pattern only over a partial range of the pattern projection area. The second pattern setting to be darkened is possible, and the influence degree of the irregular reflection of the light is measured by comparing the video signal obtained by the first pattern setting with the video signal obtained by the second pattern setting. The surface property measuring apparatus according to claim 1, wherein the degree of white turbidity due to irregular reflection of light on the measurement target surface is evaluated. The pattern setting means can set a pattern that darkens a part of the pattern projection area and brightens the surroundings. The degree of influence of the irregular reflection of the light is measured by the video signal obtained by the pattern setting, and the measurement target 2. The surface property measuring apparatus according to claim 1, wherein the degree of white turbidity due to irregular reflection of light on the surface is evaluated. 4. A brightness value calculation means for obtaining a brightness value of a pattern image by processing the video signal, and measuring the degree of influence of irregular reflection of the light based on the brightness value. The surface texture measuring apparatus as described. A pattern showing a two-dimensional distribution shape of optical brightness is formed by a display that can be controlled by a computer, the pattern is reflected by a half mirror, projected substantially perpendicular to the measurement target surface, and reflected by the measurement target surface The pattern is transmitted through the half mirror, photographed with an image sensor from a direction substantially perpendicular to the surface to be measured, and the video signal obtained by the image sensor is subjected to data processing by a computer to change the surface property of the surface to be measured. A surface texture measuring method for measuring,
A measurement condition that emphasizes the influence of irregular reflection of light from around the pattern image reflected in a partial range of the pattern projection area on the measurement target surface is realized by the setting mode of the pattern,
The degree of influence of the irregular reflection of light is measured based on a video signal obtained under measurement conditions that emphasize the influence of the irregular reflection of light, and the degree of white turbidity due to the irregular reflection of light on the measurement target surface is evaluated based on the degree of influence. A surface texture measuring method characterized by the above. The video signal is acquired with a first pattern setting for projecting an optical bright / dark pattern over the entire range of the pattern projection area, and an optical bright / dark pattern is projected only over a partial range of the pattern projection area. The video signal is acquired with a second pattern setting for darkening the surroundings, and the light signal is obtained by comparing the video signal obtained with the first pattern setting with the video signal obtained with the second pattern setting. 6. The surface property measuring method according to claim 5, wherein the degree of influence of irregular reflection is measured, and the degree of white turbidity due to irregular reflection of light on the surface to be measured is evaluated. The video signal is acquired with a pattern setting that darkens a part of the pattern projection region and brightens the surroundings, and measures the degree of influence of the irregular reflection of the light by the video signal obtained by the pattern setting, 6. The surface property measuring method according to claim 5, wherein the degree of white turbidity due to irregular reflection of light is evaluated. 8. The surface texture measuring method according to claim 5, wherein the video signal is subjected to data processing to obtain a luminance value of a pattern image, and an influence degree of irregular reflection of the light is measured based on the luminance value. .

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