JP6911647B2 - Measuring method - Google Patents

Description

The present invention relates to a measuring method for determining the thickness of a lubricating oil.

For example, when two members slide into contact with each other, lubricating oil is used. As a result, an oil film is formed between the contact surfaces of the two members, and damage such as seizure can be prevented. Since a preferable lubricating state can be obtained by setting the thickness of the oil film between the two members and the oil film around the two members to appropriate values, efforts are being made to measure the thickness of the oil film in the study of lubricating oil.

As a measurement method thereof, for example, as described in Patent Document 1, a lubricating oil in which a fluorescent substance is dispersed is applied between two members, and the brightness of fluorescence emitted from the fluorescent substance is measured by irradiating the two members with laser light. There is a method to do (laser-induced fluorescence method). This is a measurement method utilizing the fact that the amount of fluorescent substance increases as the oil film becomes thicker, so that the brightness due to fluorescence (photoexcitation) increases in proportion to the oil film thickness. As a mechanical element in which one member (object) comes into contact with another member to form an oil film as described above, for example, there is a sealing device (seal).

Japanese Unexamined Patent Publication No. 06-174431

In the case of the above-mentioned measuring method, a correlation between the thickness of the lubricating oil containing a fluorescent substance and the brightness (luminance value) of the fluorescent substance is obtained in advance using a test gauge. For example, as shown in FIG. 9A, a lubricating oil 93 containing a fluorescent substance is sandwiched between a flat surface 91 and a transparent flat plate 92, and the end portion of the flat plate 92 is placed on a block gauge 94 having a specified thickness. Therefore, the value Dn of the gap at each position Pn in the horizontal direction between the plane 91 and the flat plate 92 can be obtained by calculation. Then, a laser beam is irradiated and the brightness at each position Pn in the horizontal direction is measured by a camera (not shown) on the flat plate 92 (see FIG. 7B). Thereby, the correlation between the thickness of the oil film and the brightness can be obtained.

Then, a lubricating oil containing a fluorescent substance is applied to the object to be measured, irradiated with a laser beam, and an image showing the brightness distribution of the oil film formed on the object is acquired. From the brightness in the acquired image information, the thickness of the oil film of the object can be obtained based on the correlation.

By irradiating an object on which an oil film is formed with a laser beam of a predetermined wavelength, the fluorescent substance emits light having a specific fluorescence wavelength. However, if the object is an organic material such as rubber or resin, the fluorescence wavelength Wavelength shifts that also emit light with longer and shorter wavelengths may occur (Stokes scattering, anti-Stokes scattering), and organic materials may have weak fluorescence characteristics. In this case, the light due to the wavelength shift or the like becomes noise and the image information is acquired, and even if the thickness of the oil film of the object is obtained based on the correlation, it may be inaccurate. ..

Therefore, an object of the present invention is to provide a measuring method capable of accurately obtaining the thickness of an oil film while suppressing the influence of noise as described above.

The present invention is a measuring method for determining the thickness of an oil film formed on an object by an induced fluorescence method in which a fluorescent substance contained in a lubricating oil is photoexcited, and the oil film is irradiated with light and the oil film is irradiated with light. An imaging step of photographing the oil film by an imaging device having an image sensor, an acquisition step of acquiring brightness information regarding the brightness of each position from the image information obtained by the imaging device for each RGB color component, and the image. Of the RGB color components indicated by the spectral characteristics of the sensor, the luminance information acquired in the acquisition step for the color component close to the wavelength of the excitation light of the fluorescent substance is used as the basic luminance information and is far from the wavelength of the excitation light. Regarding the color component, the brightness information acquired in the acquisition step is used as correction information, and the correction step for correcting the basic brightness information using the correction information and the corrected basic brightness information are used as the oil film thickness and the fluorescence. It includes a measurement step of obtaining the oil film thickness by converting it by correlation with the brightness information regarding the brightness due to photoexcitation of the substance.

According to this measurement method, the object is made of an organic material such as resin or rubber, and in addition to the original fluorescence of the fluorescent substance contained in the oil film on the surface (light emission by photoexcitation), the irradiation light is emitted. Even if light due to wavelength shift during scattering and weak fluorescence due to organic materials are included in the image information as noise, the brightness information at each position is acquired separately for each RGB color component from the image information. .. Then, among the RGB color components indicated by the spectral characteristics of the image sensor, the brightness information acquired for the color component close to the wavelength of the excitation light of the fluorescent substance (that is, the original fluorescence wavelength) is used as the basic luminance information. On the other hand, the luminance information acquired for the color component far from the wavelength of the excitation light of the fluorescent substance is considered to contain a large amount of the noise, and the luminance information considered to contain a large amount of such noise is corrected. Information for use. Then, the noise can be reduced by correcting the basic luminance information using this correction information, which makes it possible to accurately obtain the oil film thickness based on the correlation.

Although it is possible to use the photographing device as a high-speed camera, the photographing device is a color digital camera, and the image information is preferably information based on a still image having an exposure time of 100 milliseconds or more. As a result, high-resolution image information can be acquired, and the resolution of oil film thickness measurement can be improved.

Further, as the correction process, the brightness value of the correction information may be subtracted from the brightness value of the basic brightness information. By this correction, the noise component can be reduced. The brightness value of the basic brightness information and the brightness value of the correction information may be normalized values.

Further, the uneven shape of the adhesion surface of the oil film of the object is measured, and based on the depth of the concave portion included in the concave-convex shape and the brightness of fluorescence by the fluorescent substance in the lubricating oil existing in the concave portion. , The preliminary step for obtaining the correlation can be further included. In this case, the method is to obtain the correlation using the actual product (object to be measured). This eliminates the need to obtain the correlation using a test piece different from the object.

According to the present invention, for example, even if light due to wavelength shift during scattering of irradiation light or weak fluorescence due to an organic material is included in image information as noise, it is possible to accurately determine the oil film thickness. It becomes.

It is a block diagram which shows an example of the measuring apparatus for carrying out the measuring method of this invention. It is explanatory drawing which shows the intensity distribution of the light emission (excitation light by a laser) of the fluorescent substance which consists of coumarin 6. It is a flow chart which shows the measurement method. It is an image diagram of a two-dimensional image based on the acquired image information. It is explanatory drawing which shows the information about the brightness of each position of the 2D image based on the acquired image information. It is explanatory drawing which shows the spectroscopic characteristic of RGB of the image sensor provided in the photographing apparatus. It is explanatory drawing which arrange | arranged the spectroscopic characteristic shown in FIG. 6 and the fluorescence characteristic of the fluorescent substance used shown in FIG. 2 with the wavelength of the horizontal axis aligned. It is a graph of the luminance value obtained by executing the correction. It is a figure explaining the conventional measurement method.

[Outline of measuring device]
The measuring method of the present invention is a method for determining the thickness of an oil film formed on an object, and is based on an induced fluorescence method performed by photoexciting a fluorescent substance contained in a lubricating oil forming the oil film. FIG. 1 is a configuration diagram showing an example of a measuring device 10 for carrying out the measuring method of the present invention.

In the measuring device 10 shown in FIG. 1, the object to be measured is a rubber sealing member 50. In FIG. 1, the seal member 50 and its periphery are shown as a cross section. The seal member 50 is annular and has a contact portion 51. The contact portion 51 is a portion that is provided so as to project from the annular main body portion 53 to one side (upward in the drawing), and is annular. The tip of the contact portion 51 contacts the flat plate member 55 having a disk shape over the entire circumference. The lubricating oil 40 is interposed between the contact portion 51 and the flat plate member 55, and an oil film 41 of the lubricating oil 40 is formed between the contact surfaces of the contact portion 51 and the flat plate member 55. In the present embodiment, a large amount of lubricating oil 40 is provided on the inner peripheral side of the contact portion 51, and no lubricating oil 40 is provided on the outer peripheral side. The flat plate member 55 is made of a transparent material (glass or resin) that transmits light. The seal member 50 and the flat plate member 55 can rotate relative to each other around the central axis C of the annular seal member 50.

The lubricating oil 40 is oil or grease. A fluorescent substance 42 is added to the lubricating oil 40, and the fluorescent substance 42 is dispersed and present in the lubricating oil 40. The fluorescent substance 42 emits fluorescence having a specific excitation wavelength by light having a predetermined wavelength. The fluorescent substance 42 can be a fluorescent dye or fluorescent particles, and rhodamine B, coumarin, or the like can be used. The fluorescent substance 42 used in this embodiment is coumarin 6.

The measuring device 10 shown in FIG. 1 executes a measuring method described later, and determines the thickness of the oil film 41 formed on the seal member 50 (contact portion 51). The measuring device 10 includes an irradiation device 11, a photographing device 12, and an arithmetic device 13.

The irradiation device 11 is installed on the side opposite to the seal member 50 (above the flat plate member 55 in the figure) with the flat plate member 55 interposed therebetween, and has a predetermined wavelength toward a part of the contact portion 51 of the seal member 50. Irradiate with light. The irradiation device 11 of the present embodiment irradiates a laser beam (semiconductor laser) having a predetermined wavelength. The irradiation device 11 may be composed of LEDs. The fluorescent substance 42 contained in the lubricating oil 40 receives the irradiation light from the irradiation device 11 and emits light. FIG. 2 is an explanatory diagram showing the intensity distribution of the emission (excitation light by the laser) of the fluorescent substance 42 made of coumarin 6, where the horizontal axis is the emission wavelength and the vertical axis is the emission intensity.

In FIG. 1, the photographing apparatus 12 of the present embodiment is configured by a color digital camera (also referred to as a color digital still camera). The photographing device 12 is installed on the same side as the irradiation device 11, that is, on the side opposite to the seal member 50 with the flat plate member 55 interposed therebetween. The photographing device 12 photographs the light irradiation region by the irradiation device 11 through the transparent flat plate member 55, and generates information of a two-dimensional image in the range included in the irradiation region. A filter 19 that cuts the laser wavelength is provided between the photographing device (camera) 12 and the flat plate member 55.

In order to generate the information of the two-dimensional image, the photographing device 12 includes an image sensor 14 (image sensor). The image sensor 14 has a large number of light receiving elements arranged on a plane, and each light receiving element outputs a signal of a level corresponding to the brightness of the light received by each of the light receiving elements. In particular, the image sensor 14 separates each of the R (red), G (green), and B (blue) color components and outputs a signal at a level corresponding to the brightness of the received light. The information of the photographed image (two-dimensional image) handled in this embodiment is a JPEG method, is processed by 8 bits, and has 256 steps (256 steps) for each of the R (red), G (green), and B (blue) color components. A signal with a level of 0 to 255) is output. The image format may be other than the JPEG method, and may be, for example, the RAW method. The signal output from the image sensor 14 indicates the brightness value at each position in the captured image. Therefore, the photographing device 12 generates information on the brightness of each of the RGB color components at each position in the captured image. The captured image may be 12 bits, 14 bits, or the like, in addition to 8 bits.

From the above, the photographing device 12 generates information on the brightness of each GRB color component at each position of the acquired photographed image (two-dimensional image) as image information (digital image information). The "information on the brightness" of the present embodiment is the brightness value. This image information is transferred from the photographing device 12 to the arithmetic unit 13, and the arithmetic unit 13 executes various processes based on the image information.

The arithmetic unit 13 is composed of a computer, a storage unit 16 for storing various information (data), an arithmetic processing unit 17 composed of a CPU, and an output unit 18 for outputting various information (for example, an image of information). It is equipped with a display that outputs as. The arithmetic unit 13 acquires the image information from the photographing device 12 and executes a predetermined process on the image information. The specific processing performed by the arithmetic unit 13 will be described later.

〔Measuring method〕
A method for determining the thickness of the oil film 41 performed by the measuring device 10 configured as described above will be described. FIG. 3 is a flow chart showing a measurement method. This measurement method includes an imaging step S1, an acquisition step S2, a correction step S3, and a measurement step S4. The measuring method of the present embodiment further includes a preliminary step S11.

[Shooting step S1]
In the photographing step S1, the irradiation device 11 irradiates the oil film 41 formed on the seal member 50 (see FIG. 1) with light, and the photographing device 12 photographs the oil film 41. As described above, the photographing device 12 generates information including the brightness value for each color component of GRB at each position of the two-dimensional image acquired by photographing as image information (digital image information). The image information is output and acquired by the arithmetic unit 13.

[Acquisition step S2]
The arithmetic unit 13 stores the image information in the storage unit 16. This image information includes the luminance value for each color component of GRB at each position. Therefore, in the acquisition step S2, the luminance information regarding the brightness of each position of the two-dimensional image based on the acquired image information is acquired for each color component and stored in the storage unit 16. The acquisition step S2, the subsequent correction step S3, and the measurement step S4 are executed according to a computer program preset in the arithmetic unit 13, and are executed by the function of the arithmetic processing unit 17 of the arithmetic unit 13. NS.

The process performed in the acquisition step S2 will be specifically described. 4 (A) and 4 (B) are image diagrams of a two-dimensional image based on the acquired image information. In the acquisition step S2, the luminance information regarding the brightness of each position is acquired for each RGB color component from the image information acquired by the photographing apparatus 12. Therefore, FIG. 4 (A) is an image diagram in which the color component of R (red) is imaged based on this luminance information, and FIG. 4 (B) is an image diagram in which the color component of G (green) is imaged. In each of FIGS. 4A and 4B, for the sake of explanation, a region having a higher luminance value has a finer crosshatch (darker color), and a region having a lower luminance value is shown in white. In this way, image information indicating the brightness distribution is acquired for each RGB color component.

In each of FIGS. 4A and 4B, the region having a low luminance value in the center in the vertical direction is the contact region between the tip of the contact portion 51 of the seal member 50 (see FIG. 1) and the flat plate member 55. A thin oil film 41 is formed in this region, the amount of the fluorescent substance 42 is relatively small, and the brightness value is low. However, in this region (see FIG. 4B), there are a plurality of portions Q in which the fluorescent substance 42 is locally larger than the surroundings and the brightness is high. This is because a recess is formed on the surface (contact surface with the flat plate member 55) of the contact portion 51 of the seal member 50 (see FIG. 1), and the lubricating oil 40 containing the fluorescent substance 42 is discharged from the periphery of the recess. This is because there are many. That is, the portion Q whose brightness is locally high indicates a recess on the surface of the contact portion 51. This recess is, for example, several tens of micrometers. In each of FIGS. 4 (A) and 4 (B), a large amount of lubricating oil 40 is present between the seal member 50 and the flat plate member 55, and a large amount of fluorescent substance 42 is present in the region having a high brightness value on the lower side in the vertical direction. ..

FIG. 5 is an explanatory diagram showing information on the brightness of each position of the two-dimensional image based on the acquired image information, and shows the brightness value of the color component of R (red) and the brightness value of the color component of G (green). ing. The vertical axis of FIG. 5 is the luminance value, and the horizontal axis is the position. The graph of the brightness value of the color component of G (green) is shown by a solid line, and the graph of the brightness value of the color component of R (red) is shown by a broken line. In FIG. 5, the luminance value of the B (blue) color component is omitted. Each position shown on the horizontal axis of FIG. 5 is a part of the two-dimensional image, and is a position in the range K along the alternate long and short dash line shown in FIGS. 4 (A) and 4 (B). In FIG. 5, the luminance value on the vertical axis is a normalized value.

In FIG. 5, the brightness values are higher at the two positions P1 and P2 as compared with those before and after the positions P1 and P2. These positions P1 and P2 correspond to the portion Q (recess on the surface) where the brightness is locally increased at two locations along the alternate long and short dash line in the range K shown in FIG. 4 (B).

As described above, the luminance information for each color component relating to the luminance at each position as shown in FIG. 5 is acquired by the function of the arithmetic processing unit 17 and stored in the storage unit 16. As described above, in the acquisition step S2, the luminance information regarding the brightness of each position is acquired for each RGB color component from the image information acquired by the photographing apparatus 12.

[Correction step S3]
Here, FIG. 6 is an explanatory diagram showing the RGB spectral characteristics of the image sensor 14 included in the photographing apparatus 12 (color digital camera) used in the present embodiment. That is, the image sensor 14 of the photographing apparatus 12 (color digital camera) used has the RGB spectral characteristics shown in FIG. The vertical axis of FIG. 6 is the spectral sensitivity, and the horizontal axis is the wavelength. The peaks of spectral sensitivity occur at different wavelengths for each of RGB. The spectral characteristics vary depending on the type of image sensor 14 used.

FIG. 7 is an explanatory diagram in which the spectral characteristics shown in FIG. 6 and the fluorescence characteristics of the fluorescent substance 42 (coumarin 6) used shown in FIG. 2 are arranged with the wavelengths on the horizontal axis aligned. In the correction step S3, as the first process, the luminance information acquired for each of the RGB color components in the acquisition step S2 is distinguished (separated) into "basic luminance information" and "correction information". In the present embodiment, the luminance information of the G (green) color component is set as "basic luminance information", and the luminance information of the R (red) color component is set as "correction information". Then, as will be described later, the "basic luminance information" is corrected by using the "correction information" as the second process.

The criteria for distinguishing between "correction information" and "basic luminance information" as described above are as follows. That is, among the RGB color components indicated by the spectral characteristics of the image sensor 14, the luminance information acquired in the acquisition step S2 for the color components close to the wavelength of the excitation light of the fluorescent substance 42 is referred to as “basic luminance information”. On the other hand, among the RGB color components indicated by the spectral characteristics of the image sensor 14, the luminance information acquired in the acquisition step S2 for the color components far from the wavelength of the excitation light of the fluorescent substance 42 is referred to as “correction information”. ..

The first treatment performed using this distinction standard will be described in more detail. In FIG. 7, the light emission distribution of the fluorescent substance 42 (cumarin 6) due to the excitation light (lower part of FIG. 7) and the distribution of the spectral sensitivities of each of RGB indicated by the spectral characteristics of the image sensor 14 (upper part of FIG. 7). The brightness information acquired in the acquisition step S2 is obtained for the color component closest to the emission distribution due to the excitation light (lower part of FIG. 7) from the distribution of the spectral sensitivities of each of RGB (upper part of FIG. 7). "Basic brightness information". The "near (far)" when compared as described above may be based on the contrast of the peak wavelengths of each distribution, that is, the magnitude of the difference between the peak wavelengths. Based on the integral value of each distribution. In the present embodiment shown in FIG. 7, the emission distribution due to the excitation light (lower part of FIG. 7) is closest to the distribution of the spectral sensitivity of G (green) indicated by the spectral characteristics of the image sensor 14 (upper part of FIG. 7). Therefore, the luminance information acquired in the acquisition step S2 for the color component of G (green) is referred to as “basic luminance information”.

Similarly, the light emission distribution due to the excitation light (bottom of FIG. 7) is compared with the distribution of the spectral sensitivities of each of RGB (top of FIG. 7) shown by the spectral characteristics of the image sensor 14, and the distribution of the spectral sensitivities of each of RGB is compared. The luminance information acquired in the acquisition step S2 for the color component farthest from the emission distribution due to the excitation light (lower part of FIG. 7) from (upper part of FIG. 7) is referred to as “correction information”. In the present embodiment shown in FIG. 7, since the emission distribution due to the excitation light (lower part of FIG. 6) is the farthest from the distribution of the spectral sensitivity of R (red), the color component of R (red) is acquired in the acquisition step S2. The obtained luminance information is referred to as "corrected luminance information". The "far" when compared as described above is that the overlap between the emission distribution of the excitation light of the fluorescent substance 42 and the spectral sensitivity distribution of R (red) is small (compared to other color components). Has the same meaning.

As described above, the emission distribution of the fluorescent substance 42 due to the excitation light (bottom of FIG. 7) and the sensitivity distribution of R (red) indicated by the spectral characteristics of the image sensor 14 (top of FIG. 7) are far from each other in terms of wavelength. There is a relationship (separate relationship). Therefore, as shown in FIG. 4 (A), the R (red) acquired in the acquisition step S2 is compared with the image diagram imaged based on the luminance information of the color component of G (green) shown in FIG. 4 (B). In the image diagram imaged based on the brightness information of the color components of the above, the portion Q whose brightness is locally increased due to the presence of a large amount of lubricating oil containing the fluorescent substance 42 does not appear. Then, as shown in FIG. 5, in the graph of the luminance information based on the color component of G (green), the luminance is higher at the two positions P1 and P2 as compared with the surroundings, but R (red). In the graph of the luminance information based on the color components of, even at the two positions P1 and P2, the luminance does not change significantly as compared with the surroundings.

The second process of the correction step S3 will be described. In the second process, the "basic luminance information" which is the luminance information of the G (green) color component is corrected by the "correction information" which is the luminance information of the R (red) color component.

Here, as described above, the emission distribution due to the excitation light of the fluorescent substance 42 (lower part of FIG. 7) and the sensitivity distribution for R (red) indicated by the spectral characteristics of the image sensor 14 (upper part of FIG. 7) are There is a distant relationship (distant relationship) with respect to wavelength. Therefore, the luminance information of the color component of R (red) does not (mostly) include the component of light emission due to the excitation light of the fluorescent substance 42. That is, most of the luminance information (luminance value) of the R (red) color component is based on the luminance other than the light emitted by the excitation light of the fluorescent substance 42. In the image diagram (image with the color component of R (red)) shown in FIG. 4 (A), the fluorescent component of the fluorescent substance 42 is (almost) not contained. On the other hand, in the image diagram (image with the color component of G (green)) shown in FIG. 4 (B), the fluorescent component of the fluorescent substance 42 is included, and components other than the fluorescent component are also included.

Therefore, in the present embodiment, the brightness of the color component of R (red) is regarded as an unnecessary component (noise) for light emission by the excitation light of the fluorescent substance 42.

Therefore, in the second process, as the correction process, the brightness value of the "basic luminance information" which is the luminance information of the G (green) color component is changed to the "correction information" which is the luminance information of the R (red) color component. The brightness value of "" is subtracted. FIG. 8 is a graph of the luminance value obtained by executing this correction. In FIG. 8, the thick solid line is a graph showing the corrected luminance value, and at each position, the luminance information of the R (red) color component is obtained from the luminance value indicated by the luminance information of the G (green) color component. The value obtained by subtracting the indicated brightness value is shown.

In this way, the luminance information of the R (red) color component, which is considered to contain a lot of noise, is referred to as "correction information", and the luminance information of the G (green) color component is used using this "correction information". The noise can be reduced by correcting the "basic luminance information".

[Measurement step S4]
In the measurement step S4, the "basic luminance information" corrected by the second process of the correction step S3 is converted by the correlation between the oil film thickness and the information on the luminance due to photoexcitation of the fluorescent substance 42 (in the present embodiment, the luminance value), and the oil film is converted. Find the thickness. The correlation may be obtained by a conventionally used method (see FIG. 9), but in the present embodiment, it is based on the correlation obtained by using the seal member 50 to be measured in the preliminary step S11 described later. ..

The corrected "basic luminance information" indicates the luminance value at each position in FIG. Since the luminance value has a correlation with the thickness of the oil film 41 due to the lubricating oil 40 containing the fluorescent substance 42, the thickness of the oil film 41 at each position can be obtained by this correlation based on the luminance value at each position.

[Preliminary step S11]
Preliminary step S11 is performed independently of steps S1 to S4 (see FIG. 3). In the preliminary step S11, the uneven shape (three-dimensional shape) of the adhesion surface of the oil film formed on the surface of the seal member 50 (contact portion 51) is measured. This measurement is performed by precisely measuring the depth of the recess with, for example, a three-dimensional shape measuring device. Then, the lubricating oil 40 containing the fluorescent substance 42 is present in the specific concave portion whose depth is measured, and the concave portion is photographed by the photographing device 12 to obtain the brightness value (signal at a level corresponding to the brightness). .. Since the measured depth of the recess coincides with the thickness of the lubricating oil 40 existing in the recess, the relationship (correlation) between the thickness of the lubricating oil 40 and the brightness value can be obtained.

In this way, the uneven shape of the adhesion surface of the oil film 41 of the sealing member 50 (contact portion 51) is measured, and the depth of the concave portion included in the uneven shape and the fluorescent substance 42 in the lubricating oil 40 existing in the concave portion are used. The correlation may be determined based on the brightness of fluorescence. In this case, it is not necessary to obtain the correlation by using a test piece different from the object (seal member 50) as in the conventional case (see FIG. 9).

[Measurement method]
From the above, in the present embodiment, the object on which the oil film 41 is formed is the seal member 50, and the seal member 50 is made of an organic material such as rubber. Therefore, in the photographing step S1, in addition to the original fluorescence of the fluorescent substance 42 contained in the oil film 41 on the surface thereof (light emission by light excitation), light due to wavelength shift when the irradiation light is scattered and weak fluorescence due to the organic material are generated. , It becomes noise and is included in the image information acquired by the photographing apparatus 12.

However, according to the measurement method using the measuring device 10 as described above, the luminance information of each position is separately acquired for each RGB color component from the image information acquired by the photographing device 12 (photographing step S1). Acquisition step S2). Then, among the RGB color components indicated by the spectral characteristics of the image sensor 14 of the photographing apparatus 12 to be used, the color components close to the wavelength of the excitation light of the fluorescent substance 42 (that is, the original fluorescence wavelength) (in the present embodiment, The brightness information acquired for (the color component of G) is referred to as "basic brightness information". On the other hand, it is considered that the luminance information acquired for the color component far from the wavelength of the excitation light of the fluorescent substance 42 (in the present embodiment, the color component of R) contains a large amount of noise as described above. Luminance information that is considered to contain a large amount of such noise is referred to as "correction information". Then, the noise can be reduced by correcting the "basic luminance information" using this "correction information".

In the present embodiment, as the correction process, the brightness value of the "correction information" is subtracted from the brightness value of the "basic brightness information". This makes it possible to accurately determine the oil film thickness using the correlation. As a result, the lubrication state of the seal member 50 can be accurately known, and the reliability of the seal member 50 and the device including the seal member 50 can be improved and the life of the seal member 50 can be extended.

Although it is possible to use the photographing device 12 as a high-speed camera, in the present embodiment, the photographing device 12 is a color digital camera, and the signal to be processed is a color signal. The image information acquired by the color digital camera is preferably information based on a still image having an exposure time of 100 milliseconds or more. As a result, high-resolution image information can be acquired, and the resolution of oil film thickness measurement can be improved. The upper limit of the exposure time differs depending on the object to be measured.

As the photographing device 12, a monochrome camera may be used in addition to the color digital camera as described above. However, in this case, three monochrome cameras are required, and RGB optical filters are installed in each of these monochrome cameras. As a result, the signals of the color components of each of RGB are acquired from these monochrome cameras, and the same processing as in the above-described embodiment is performed. If it is known in advance that the signal of the B (blue) color component is not used as in the above embodiment, a monochrome camera to which the B (blue) optical filter is attached is unnecessary, and two monochrome cameras are not required. You only need a camera.

The embodiments disclosed as described above are exemplary in all respects and are not restrictive. That is, the measuring method of the present invention is not limited to the illustrated form, and may be another form within the scope of the present invention.
In the above embodiment, the object on which the oil film 41 is formed is the seal member 50, but the object may be a mechanical element other than the seal member 50. Further, even when the seal member 50 is used, the shape thereof may be other than the shape shown in the drawing.
Moreover, the fluorescent substance used can be another substance.

10: Measuring device 11: Irradiation device 12: Imaging device 13: Arithmetic device 14: Image sensor 40: Lubricating oil 41: Oil film 42: Fluorescent substance 50: Sealing member (object)

Claims (4)

It is a measurement method for determining the thickness of an oil film formed on an object by an induced fluorescence method in which a fluorescent substance contained in a lubricating oil is photoexcited.
A photographing step of irradiating the oil film with light and photographing the oil film with an imaging device having an image sensor.
From the image information obtained by the photographing apparatus, the acquisition step of acquiring the luminance information regarding the luminance of each position for each RGB color component, and the acquisition step.
Among the RGB color components indicated by the spectral characteristics of the image sensor, the luminance information acquired in the acquisition step for the color component close to the wavelength of the excitation light of the fluorescent substance is used as the basic luminance information, and the wavelength of the excitation light is used. A correction step in which the luminance information acquired in the acquisition step for a color component distant from the light is used as correction information, and the basic luminance information is corrected using the correction information.
A measurement step of converting the corrected basic brightness information by the correlation between the oil film thickness and the brightness information related to the brightness due to photoexcitation of the fluorescent substance to obtain the oil film thickness.
Measurement methods, including. The photographing device is a color digital camera.
The measuring method according to claim 1, wherein the image information is information based on a still image having an exposure time of 100 milliseconds or more. The measurement method according to claim 1 or 2, wherein as the correction process, the brightness value of the correction information is subtracted from the brightness value of the basic brightness information. The uneven shape of the adhesion surface of the oil film of the object is measured, and based on the depth of the concave portion included in the concave-convex shape and the brightness of fluorescence by the fluorescent substance in the lubricating oil existing in the concave portion, the said The measurement method according to any one of claims 1 to 3, further comprising a preliminary step for obtaining a correlation.

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