WO2022220309A1 - Method and device for determining a uv coverage percentage after real life stress - Google Patents

Method and device for determining a uv coverage percentage after real life stress Download PDF

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Publication number
WO2022220309A1
WO2022220309A1 PCT/JP2022/018496 JP2022018496W WO2022220309A1 WO 2022220309 A1 WO2022220309 A1 WO 2022220309A1 JP 2022018496 W JP2022018496 W JP 2022018496W WO 2022220309 A1 WO2022220309 A1 WO 2022220309A1
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WIPO (PCT)
Prior art keywords
target
light
image
protection product
coverage
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PCT/JP2022/018496
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French (fr)
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WO2022220309A8 (en
Inventor
Alexandre Nicolas
Ayako Nakamura
Sheila Qiu
Yuri NAKANO
Original Assignee
L'oreal
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Priority claimed from JP2021068391A external-priority patent/JP2022163456A/en
Priority claimed from FR2104957A external-priority patent/FR3122922B1/en
Application filed by L'oreal filed Critical L'oreal
Publication of WO2022220309A1 publication Critical patent/WO2022220309A1/en
Publication of WO2022220309A8 publication Critical patent/WO2022220309A8/en

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/8422—Investigating thin films, e.g. matrix isolation method
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
    • G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
    • G01N21/64—Fluorescence; Phosphorescence
    • G01N21/645—Specially adapted constructive features of fluorimeters
    • G01N21/6456—Spatial resolved fluorescence measurements; Imaging
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
    • G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
    • G01N21/64—Fluorescence; Phosphorescence
    • G01N21/6428—Measuring fluorescence of fluorescent products of reactions or of fluorochrome labelled reactive substances, e.g. measuring quenching effects, using measuring "optrodes"
    • G01N2021/6439—Measuring fluorescence of fluorescent products of reactions or of fluorochrome labelled reactive substances, e.g. measuring quenching effects, using measuring "optrodes" with indicators, stains, dyes, tags, labels, marks
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
    • G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
    • G01N21/64—Fluorescence; Phosphorescence
    • G01N21/645—Specially adapted constructive features of fluorimeters
    • G01N2021/6463—Optics
    • G01N2021/6471—Special filters, filter wheel
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/8422—Investigating thin films, e.g. matrix isolation method
    • G01N2021/8427—Coatings
    • G01N2021/8433—Comparing coated/uncoated parts

Definitions

  • the present invention relates to a method and a device for determining a UV coverage percentage after real life stress.
  • UV protection Protection of a target such as human skin from ultraviolet light (UV protection) is important for skin health and beauty.
  • a formulation having a UV protection effect i.e., sunscreen is applied onto a target
  • the sunscreen will eventually be removed by stresses on the sunscreen such as wetting the target, wiping the target with a towel, or by the passage of time. Therefore, the effect of the sunscreen will eventually be lost by stresses and by the passage of time.
  • For effective protection of the target it is necessary to measure the current protection effect.
  • ultraviolet light is invisible to the human eye, the UV protection effect also cannot be seen. Therefore, a consumer cannot visually check the degree to which the UV protection effect is maintained.
  • FIG. 10 shows a conventional method of determining the intensity of fluorescent light emitted from a target in response to the irradiation of UV light.
  • the method irradiates a target 1010 with light 1016 including UV light.
  • the target 1010 emits fluorescent light 1020 in response to the irradiation of light 1016.
  • the optical sensor 1006 outputs a signal depending on the intensity of the fluorescent light 1020.
  • the change of the intensity of the fluorescent light is calculated with the following equation ⁇
  • Timm represents the intensity of the fluorescent light measured immediately after applying a UV protection product onto the target
  • Ti represents an intensity of the fluorescent light measured after applying a predetermined number of stresses to the UV protection product
  • this conventional method can carry out the measurement on only one portion of the target at a time.
  • the target is a human face
  • Imaging systems which can obtain standard images of a human face as a target under certain irradiation conditions have been developed.
  • the Visia system of Canfield Scientific, Inc. is commercially available.
  • the UV imaging function of such an imaging system is often used to estimate and show pigmentation spots significantly absorbing UV light.
  • the UV imaging function is often used as an example showing the effect of a UV protection product.
  • Non-Patent Document 1 reported the use of a blue fluorescent pigment for estimating a resistance of a UV protection product for some types of water.
  • UV patch aim to obtain real time data and change of a UV protection level based on a photosensitive patch developed in response to UV irradiation.
  • the UV patch has the advantage of portability, the UV patch does not aim to evaluate the distribution of a UV protection product applied thereon.
  • the UV patch requires the intentional irradiation of UV light, in other words, the UV patch does not respond unless the patch is exposed to sunlight.
  • the present invention aims to quantify changes of a spatial distribution of a UV protection product and its uniformity with respect to an initial uniform application of a sufficient amount of the UV protection product, which is referred to as “UV coverage”. It should be noted that the present invention does not aim to estimate the Sun Protection Factor, SPF, of a UV protection product applied onto the surface of skin.
  • SPF Sun Protection Factor
  • a method of determining a UV coverage of a UV protection product by a measurement process comprises the steps of obtaining an image of a target by irradiating the target with light before applying a UV protection product onto the target; obtaining an image of the target by irradiating the target with light after applying the UV protection product onto the target; obtaining an image of the target by irradiating the target with light after applying a stress to the target on which the UV protection product is applied; setting at least one region of interest on the target in the image obtained in each image obtaining step; obtaining intensities of detected light in the regions of interest in the images obtained from the image obtaining steps; and determining a UV coverage of the UV protection product by comparing the intensities of the detected light in the regions of interest in the images obtained the image obtaining steps.
  • the step of obtaining the image of the target by irradiating the target with light after applying the stress to the target onto which the UV protection product is applied may be carried out one or more times.
  • the step of determining the UV coverage of the UV protection product may determine the UV coverage of the UV protection product based on the following equation:
  • the steps of obtaining the image of the target may comprise obtaining an image of fluorescent light emitted from the target in response to irradiating the target with light.
  • the steps of obtaining the image of the target may comprise reducing or blocking fluorescent light having a wavelength other than a range between 290 and 420 nm by filtering.
  • the target may be a human face or a dummy sample including a fluorescent substance similar to a fluorescent substance included in human skin.
  • the step of setting the at least one region of interest may comprise setting a plurality of regions of interest on a human face, and the step of determining the UV coverage may comprise determining the UV coverages in the plurality of regions of interest at the same time.
  • the light for irradiating the target may have a wavelength in the ultraviolet light range.
  • a device for determining a UV coverage of a UV protection product comprises: a light source for irradiating a target with light; a detector for obtaining images of the target in response to irradiating the target with light; and a controller for determining a UV coverage of a UV protection product applied onto the target based on the images of the target obtained by the detector, wherein the controller is configured to set at least one region of interest on the target in the images, and wherein the controller is configured to determine the UV coverage of the UV protection product by comparing intensities of the detected light in the regions of interest in an image of the target before applying the UV protection product onto the target, an image of the target after applying the UV protection product onto the target, and an image of the target after applying a stress to the target onto which the UV protection product is applied.
  • the image of the target after applying the stress to the target onto which the UV protection product is applied may be obtained one or more times.
  • the controller may be configured to determine the UV coverage of the UV protection product based on the following equation:
  • Timm represents the intensity of the detected light obtained from the image of the target after applying the UV protection product onto the target
  • Ti represents the intensity of the detected light obtained from the image of the target after applying an ith stress to the target onto which the UV protection product is applied
  • i represents an integer larger than or equal to 1.
  • the detector may be configured to obtain an image of fluorescent light emitted from the target in response to irradiating the target with light.
  • the detector may comprise a filter configured to reduce or block fluorescent light having a wavelength other than a range between 420 and 520 nm by filtering.
  • the target may be a human face or a dummy sample including a fluorescent substance similar to a fluorescent substance included in human skin.
  • the at least one region of interest may be a plurality of regions of interest on a human face, and the controller may be configured to determine the UV coverage in the plurality of regions of interest at the same time.
  • the light source may be configured to irradiate the target with light having a wavelength in the ultraviolet light range.
  • a method and device for determining a UV coverage of a UV protection product are provided.
  • Figure 1 shows a schematic view of a device for determining the UV coverage of a UV protection product according to some embodiments of the present invention.
  • Figure 2 schematically shows a flow chart of a method of determining the UV coverage of a UV protection product according to some embodiments of the present invention.
  • Figure 3A shows an illumination spectrum of a Visis UV light having a range from 290 nm to 420 nm.
  • Figure 3B shows intensities in R, G, and B channels of fluorescent light emitted from human skin in response to UV light irradiation in the method of determining the UV coverage of a UV protection product according to some embodiments of the present invention.
  • Figure 4 shows images of the fluorescent light obtained in R, G, and B channels in the method of determining the UV coverage of a UV protection product according to some embodiments of the present invention.
  • Figure 5 shows an example of setting regions of interest on the target in the method of determining the UV coverage of a UV protection product according to some embodiments of the present invention.
  • Figure 6 shows UV coverages obtained by the method of determining the UV coverage of a UV protection product according to some embodiments of the present invention.
  • Figure 7 shows changes of fluorescent light obtained by a conventional method for comparison.
  • Figure 8 shows a correlation relationship between the UV coverages obtained by the method according to some embodiments of the present invention and the changes of fluorescent light obtained by the conventional method.
  • Figure 9 shows UV coverages obtained for different kinds of UV protection products by the method of determining the UV coverage of the UV protection product according to some embodiments of the present invention.
  • Figure 10 shows a conventional method of measuring the intensity of fluorescent light emitted from a target in response to irradiating the target with UV light.
  • a device 1 for determining an ultraviolet light coverage (UV coverage) may comprise: a light source 2 for irradiating a target 10 with light 16; a detector 6 for obtaining an image of the target 10 in response to irradiating the target 10 with the light 16; and a controller 8 for determining the UV coverage of an ultraviolet light protection product (UV protection product) 12 applied on the target 10 based on the image obtained by the detector 6 as shown in Figure 1.
  • a light source 2 for irradiating a target 10 with light 16
  • a detector 6 for obtaining an image of the target 10 in response to irradiating the target 10 with the light 16
  • a controller 8 for determining the UV coverage of an ultraviolet light protection product (UV protection product) 12 applied on the target 10 based on the image obtained by the detector 6 as shown in Figure 1.
  • the light source 2 may emit the light 16 including ultraviolet light (UV light).
  • the light source 2 may be a known light source, for example, a mercury light or an LED.
  • the light source 2 may emit light having a wavelength in a wide range including UV light, visible light, and infrared light.
  • the light source 2 may comprise an optional filter 22 to transmit only light having a desirable wavelength range.
  • Such a filter 22 may allow light having a wavelength in, for example, the UV light range, to pass through.
  • the filter 22 may allow UV light, for example, light having a UVA or UV-B wavelength, or in particular, UV light including a wavelength of 365 nm, to pass through.
  • the light source 2 may emit only UV light.
  • the light source 2 may emit monochromatic UV light, for example, light having a UVA or UV-B wavelength.
  • the light source 2 may be a UV LED emitting UV light including a wavelength of 365 nm. If the light source 2 emits only UV light, the light source 2 does not have to comprise the filter 22.
  • the target 10 may be, for example, human skin, in particular, a human face.
  • the human skin may include at least one fluorescent substance which may emit fluorescent light 20 in, for example, the visible light range in response to irradiation of light, in particular, irradiation of UV light.
  • a fluorescent substance may be, for example, collagen, NADPH, or an amino acid.
  • the target 10 may be a dummy sample including a fluorescent substance similar to the fluorescent substance included in the human skin.
  • a dummy sample may be, for example, a pig’s skin, cultivated human skin, or a gel modeling human skin.
  • the UV protection product 12 applied onto the target 10 may be, for example, sunscreen.
  • the UV protection product 12 may include a material absorbing and/or reflecting UV light. Since a part of the light 16 affecting the target 10 is blocked by the UV protection product 12, the intensity of the light 16 affecting the target 10 depends on the amount of the UV protection product 12 applied onto and remaining on the target 10. Since the intensity of the fluorescent light 20 emitted from the target 10 also depends on the intensity of the light 16 incident on the target 10, the intensity of the fluorescent light 20 emitted from the target 10 and affecting the detector 6 also depends on the amount of the UV protection product 12.
  • the detector 6 may detect the intensity of the fluorescent light 20 emitted from the target 10 in response to the irradiation of the light 16 and generate a signal depending on the intensity. Alternatively, the detector 6 may detect a two- dimensional distribution of the intensity of the detected fluorescent light 20 to generate a two-dimensional image having a distribution of brightness corresponding to the intensity of the fluorescent light 20. Such a detector 6 may be a known photodetector having photosensitive elements arranged in an array. The detector 6 may be, for example, a CMOS camera or a CCD camera. The intensity of the light 16 reflected on the target 10 is generally much larger than the intensity of the fluorescent light 20.
  • the detector 6 may comprise a shield 26 for blocking the light 16 reflected on the target 10. Furthermore, the detector 6 may detect fluorescent light 20 having only a wavelength in a range desirable for determining the UV coverage. For example, the detector 6 may have relatively small sensitivity, or more preferably, no sensitivity to light having a wavelength other than the desirable wavelength range. Alternatively, the detector 6 may comprise a filter 24 at least reducing, preferably blocking, the fluorescent light 20 having a wavelength other than the preferable wavelength range. The filter 24 may be configured to reduce or block fluorescent light of a wavelength other than between 290 and 420 nm by filtering. The filter 24 may also comprise a function of blocking the light 16 reflected on the target 10.
  • the controller 8 may be configured to control the emission of the light 16 from the light source 2, the detection of the fluorescent light 20 emitted from the target 10 by the detector 6, and the generation of the image.
  • the controller 8 may also be configured to determine the UV coverage of the UV protection product from the images obtained by the detector 6. The determination of the UV coverage of the UV protection product will be described in detail below.
  • Figure 2 is a flow chart schematically showing a method 100 of determining a UV coverage of a UV protection product using the device 1.
  • the method 100 comprises a measurement process including steps 102 to 116.
  • step 102 a target 10 before applying a UV protection product 12 thereon is irradiated with the light 16, and fluorescent light 20 emitted from the target 10 is detected to obtain a first image of the target 10.
  • step 104 a predetermined amount of the UV protection product 12 is applied onto the target 10.
  • step 106 the target 10 is irradiated with the light 16, and the fluorescent 20 emitted from the target 10 is detected to obtain a second image of the target 10.
  • step 108 a predetermined stress is applied to the target 10 onto which the UV protection product 12 is applied. For example, as a stress, water may be sprayed on the target 10 and then the target 10 may be wiped with a dry cloth. If the target 10 is a human face, the subject may do an exercise such as running or riding a bike and then wipe sweat. The stress may also be the mere passage of time. Stress may also be a daily activity such as work or household chores.
  • step 110 the target 10 is irradiated with light 16 and the fluorescent light 20 emitted from the target 10 is detected to obtain an image of the target 10 after applying the stress.
  • Steps 108 and 110 may be carried out one or more times, for example, i times (i is an integer equal to or larger l) as needed, and images may be obtained a plurality of times. If step 108 is carried out a plurality of times, step 110 may be carried out for each step 108. Step 110 may be omitted after carrying out step 108 several times. In other words, step 110 may be carried out once after repeating step 108 a predetermined number of times. A set carrying out step 110 once after repeating step 108 predetermined times may be carried out a predetermined number of times. The image obtained in step 110 after carrying out step 108 i times is referred to as the image after the ith stress. If step 110 is carried out after each step 108, the number of the obtained images is i. In case of omitting the step 110, fewer than i images are obtained.
  • the positions of the target 10 in the images obtained in steps 102, 106, and 110 are preferably at least similar throughout all of the images, more preferably, identical. Furthermore, the images are preferably obtained from at least similar directions, more preferably, from the same directions. Therefore, in order to make the position of the target 10 in the image match the direction of the image when obtaining the image in the step after step 106 with the first image obtained in step 102, a step of adjusting the position and the direction of the detector 6 may be carried out before obtaining the image. Such an adjustment may be carried out by an input of an operator, or may be automatically carried out by the controller 6 based on the comparison with the first image. The adjustment by the operator may be carried out with or without the controller 6.
  • step 112 at least one region of interest is set on the target 10 in the images obtained from the image obtaining steps.
  • the region of interest may preferably be a common position throughout all of the images. If the target 10 is, for example, a human face, the regions of interest may be set on, for example, the forehead, the right cheek, and the left cheek. If the images have been adjusted such that the positions of the target in the images are similar or identical, the regions of interest may be set at common positions without any need of fine adjustment of the positions for all of the images only if the regions of interest are set for one image.
  • the controller 6 may set the regions of interest. The number, positions, and sizes of the regions of interest may be appropriately set with respect to the purpose of measurement. Setting a plurality of regions of interest may result in obtaining the distribution of the applied UV protection product 12 applied onto the target 10.
  • step 114 intensities of the detected light in the regions of interest set in the images are obtained.
  • the intensity of the detected light may correspond to the brightness in the region of interest, in other words, the gray scale value. Therefore, the gray scale value may be employed as an indicator representing the intensity of the detected light.
  • the gray scale value may be obtained by, for example, averaging the gray scale values of the pixels in the region of interest.
  • the UV coverage of the UV protection product 12 may be determined by comparing the intensities of the detected light, for example, the gray scale values in the regions of interest of the images in the image obtaining steps.
  • the UV coverage is defined by the following equation:
  • T 0 - T t i mm To is the intensity of the detected light obtained from the first image of the target 10 before applying the UV protection product 12 thereon, Timm is the intensity of the detected light obtained from the second image of the target 10 after applying the UV protection product 12 thereon, and Ti is the intensity of the detected light obtained from the image after the ith stress obtained after applying the ith stress to the target 10 onto which the UV protection product 12 is applied.
  • the gray scale values in the regions of interest in the images may be used as the intensities of the detected light as discussed above.
  • the detector 6 may preferably detect light in the blue range among the fluorescent light 20.
  • the detector 6 is a conventional CMOS camera or CCD camera having R, G, and B channels
  • images may preferably be obtained by using only the data of the B channel.
  • Figure 3A shows an illumination spectrum of a Visis UV light having a peak at 365.9 nm and a range from 290 to 420 nm.
  • Figure 3B shows the intensities of fluorescent light in the R, G, and B channels, which is emitted from human skin in response to the irradiation of UV light. It is shown that the intensity in the B channel is highest.
  • Figure 4 shows images of fluorescent light in the R, G, and B channels emitted from a human face in response to the irradiation of UV light. It is shown that the image of the B channel has the largest brightness and the highest contrast. Therefore, when the data in the B channel is used, the UV coverage may be determined with a high resolution and a high accuracy.
  • the detector 6 may comprise a filter 24 for reducing or blocking light having a wavelength other than the B channel wavelength.
  • the filter 24 may reduce or block light having a wavelength other than the range between 290 and 420 nm.
  • the measurement was then carried out before applying a UV protection product.
  • the subject’s face was irradiated with UV light by using the device 1, and a first image was obtained based on fluorescent light emitted from the face.
  • the left and right sides of the forehead and the left and right cheeks were irradiated with UV light and the intensities of the emitted fluorescent light were measured by the conventional method.
  • the measurement was then carried out after applying the UV protection products. Specifically, the second image was obtained by using the device 1. The intensities of the fluorescent light were also measured by the conventional method. [0061] Next, the subject had a light meal in an environment at 22°C and 45% humidity within 30 minutes. After the meal, an operator sprayed 2.5 g of water mist on the entire face for 3 seconds from a distance of 20 cm as the first stress. A paper towel was then put on the entire face to remove moisture.
  • the subject spent 40 minutes in an environment at 30 to 32°C and 30% of humidity, and performed an exercise on a fitness bike in an environment of 20 to 30°C and 30% humidity for tern minutes. During the exercise, the subject was requested to maintain the heart rate at 130 beats/minute. Next, a paper towel was put on the entire face to remove sweat. The acclimation was carried out at 22°C and 45% humidity for 30 minutes.
  • the measurement was then carried out after the second stress. Specifically, the image after the second stress was obtained by using the device 1. The intensities of the fluorescent light were also measured by the conventional method.
  • the measurement was carried out after the third stress. Specifically, the image after the third stress was obtained by using the device 1. The intensities of the fluorescent light were also measured by the conventional method.
  • regions of interest were set on the left and right sides of the forehead and left and right cheeks by using the device 1 as shown in Figure 5.
  • the regions of interest were set such that the regions where the intensities of fluorescent light were measured by the conventional method were included in the regions of interest.
  • the gray scale values of the regions of interest were determined by averaging the gray scale values in the regions of interest in the images.
  • T 0 - mm T 0 - mm
  • Timm is the gray scale value obtained from the second image of the subject’s face after applying the UV protection products thereon
  • Ti is the gray scale value obtained from the image after the ith stress was applied to the subject’s face onto which the UV protection product was applied.
  • the gray scale values correspond to the intensities of the fluorescent light emitted from the subject’s face and detected.
  • the change of fluorescent light obtained by the conventional method after the ith stress was determined by the following equation: 100 where Timm is the intensity of the fluorescent light from the subject’s face which was measured based on the conventional method after applying the UV protection products onto the subject’s face, and Ti is the intensity of the fluorescent light which was measured based on the conventional method after applying the ith stress to the subject’s face onto which the UV coverage was applied.
  • FIG. 6 shows the UV coverage obtained by the method of the present invention. It can be seen that the UV coverage decreases for each application of stress regarding the two types of UV protection products (858419 5) and (884474 l) which were applied onto the forehead and cheeks.
  • Figure 7 shows the change of the intensity of the fluorescent light obtained by the conventional method shown in Figure 10 for comparison. It can be seen that the intensity of the fluorescent light increases for each application of stress regarding the two types of UV protection products (858419 5) and (884474 l) which were applied onto the forehead and cheeks.
  • FIG. 8 shows the correlation relationship between the UV coverage obtained by the method of the present invention and the change of the intensity of the fluorescent light obtained by the conventional method.
  • the UV coverage exhibits a good correlation with the change of the intensity of the fluorescent light, and therefore it can be seen that the UV protection effect of a UV protection product can be evaluated by measuring the UV coverage instead of the change of the intensity of the fluorescent light.
  • the method of the present invention can obtain UV coverages at a plurality of portions in an image of a target at the same time, the UV protection effect of a UV protection product at a plurality of portions in the target can be evaluated at the same time, and the distribution of the UV protection product can be also evaluated.
  • Figure 9 shows the UV coverages obtained by the method of the present invention for two types of UV protection products (858419 5) and (884474 l).
  • Figure 9 shows that (884474 1) has a higher resistance for stresses than (858419 5). Since the method of the present invention can evaluate UV coverages of a plurality of types of UV protection products applied on different portions on a target, different types of UV protection products can be easily and accurately compared.
  • UV protection product 16 Light

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Abstract

The present invention provides a method of determining a UV coverage of a UV protection product. The method of determining a UV coverage of a UV protection product by a measurement process comprises the steps of obtaining an image of a target by irradiating the target with light before applying a UV protection product onto the target; obtaining an image of the target by irradiating the target with light after applying the UV protection product onto the target; obtaining an image of the target by irradiating the target with light after applying a stress to the target onto which the UV protection product is applied; setting at least one region of interest on the target in the image obtained in each image obtaining step; obtaining intensities of detected light in the regions of interest in the images obtained from the image obtaining steps; and determining a UV coverage of the UV protection product by comparing the intensities of the detected light in the regions of interest in the images obtained the image obtaining steps.

Description

DESCRIPTION
Title of Invention
METHOD AND DEVICE FOR DETERMINING A UV COVERAGE PERCENTAGE AFTER REAL LIFE STRESS
Technical Field
[0001] The present invention relates to a method and a device for determining a UV coverage percentage after real life stress.
Background
[0002] Protection of a target such as human skin from ultraviolet light (UV protection) is important for skin health and beauty. After applying a formulation having a UV protection effect, i.e., sunscreen is applied onto a target, the sunscreen will eventually be removed by stresses on the sunscreen such as wetting the target, wiping the target with a towel, or by the passage of time. Therefore, the effect of the sunscreen will eventually be lost by stresses and by the passage of time. For effective protection of the target, it is necessary to measure the current protection effect. However, since ultraviolet light is invisible to the human eye, the UV protection effect also cannot be seen. Therefore, a consumer cannot visually check the degree to which the UV protection effect is maintained.
[0003] When a target is irradiated with UV light, fluorescent substances such as collagen, NADPH, and amino acids included in the target emit, for example, fluorescent light in a visible range. The amount of UV light reaching the irradiation target, in other words, the UV protection effect of the sunscreen applied onto the irradiation target, can be determined by measuring the amount of the fluorescent light. [0004] Figure 10 shows a conventional method of determining the intensity of fluorescent light emitted from a target in response to the irradiation of UV light. The method irradiates a target 1010 with light 1016 including UV light. The target 1010 emits fluorescent light 1020 in response to the irradiation of light 1016. When the fluorescent light 1020 is incident on an optical sensor 1006, the optical sensor 1006 outputs a signal depending on the intensity of the fluorescent light 1020. The change of the intensity of the fluorescent light is calculated with the following equation^
Afluorescence 100
Figure imgf000003_0001
[0005] where Timm represents the intensity of the fluorescent light measured immediately after applying a UV protection product onto the target, and Ti represents an intensity of the fluorescent light measured after applying a predetermined number of stresses to the UV protection product.
[0006] However, this conventional method can carry out the measurement on only one portion of the target at a time. For example, when the target is a human face, it is difficult to evaluate the UV protection effect at a plurality of portions of the face such as the forehead and left and right cheeks at the same time, and to evaluate the distribution of the UV protection effect.
[0007] Imaging systems which can obtain standard images of a human face as a target under certain irradiation conditions have been developed. For example, the Visia system of Canfield Scientific, Inc. is commercially available. The UV imaging function of such an imaging system is often used to estimate and show pigmentation spots significantly absorbing UV light. Furthermore, the UV imaging function is often used as an example showing the effect of a UV protection product. However, to the best of the inventor’s knowledge, such imaging systems have not been used to directly quantify a temporal change of the distribution of a UV protection product on the skin’s surface. Non-Patent Document 1 reported the use of a blue fluorescent pigment for estimating a resistance of a UV protection product for some types of water.
[0008] Other systems developed by L’Oreal, for example, a UV patch, aim to obtain real time data and change of a UV protection level based on a photosensitive patch developed in response to UV irradiation. Although the UV patch has the advantage of portability, the UV patch does not aim to evaluate the distribution of a UV protection product applied thereon. Furthermore, the UV patch requires the intentional irradiation of UV light, in other words, the UV patch does not respond unless the patch is exposed to sunlight.
Non-Patent Document L Chutima Rungananchai, et al., “Sunscreen Application to the Face Persists beyond 2 Hours in Indoor Workers; an Open-Label Trial”, Journal of Dermatological Treatment, Volume 30, 2019, Issue 5, Pages 483-486
Summary of Invention
[0009] The present invention aims to quantify changes of a spatial distribution of a UV protection product and its uniformity with respect to an initial uniform application of a sufficient amount of the UV protection product, which is referred to as “UV coverage”. It should be noted that the present invention does not aim to estimate the Sun Protection Factor, SPF, of a UV protection product applied onto the surface of skin. [0010] A method of determining a UV coverage of a UV protection product by a measurement process according to one embodiment of the present invention comprises the steps of obtaining an image of a target by irradiating the target with light before applying a UV protection product onto the target; obtaining an image of the target by irradiating the target with light after applying the UV protection product onto the target; obtaining an image of the target by irradiating the target with light after applying a stress to the target on which the UV protection product is applied; setting at least one region of interest on the target in the image obtained in each image obtaining step; obtaining intensities of detected light in the regions of interest in the images obtained from the image obtaining steps; and determining a UV coverage of the UV protection product by comparing the intensities of the detected light in the regions of interest in the images obtained the image obtaining steps.
[0011] In one embodiment of the present invention, the step of obtaining the image of the target by irradiating the target with light after applying the stress to the target onto which the UV protection product is applied may be carried out one or more times. [0012] In one embodiment of the present invention, the step of determining the UV coverage of the UV protection product may determine the UV coverage of the UV protection product based on the following equation:
UV Coverage[ 100
Figure imgf000005_0001
where To represents the intensity of the detected light obtained from the image of the target before applying the UV protection product, Timm represents the intensity of the detected light obtained from the image of the target after applying the UV protection product onto the target, Ti represents the intensity of the detected light obtained from the image of the target after applying an ith stress to the target onto which the UV protection product is applied, and i represents an integer equal to or larger than 1.
[0013] In one embodiment of the present invention, the steps of obtaining the image of the target may comprise obtaining an image of fluorescent light emitted from the target in response to irradiating the target with light.
[0014] In one embodiment of the present invention, the steps of obtaining the image of the target may comprise reducing or blocking fluorescent light having a wavelength other than a range between 290 and 420 nm by filtering.
[0015] In one embodiment of the present invention, the target may be a human face or a dummy sample including a fluorescent substance similar to a fluorescent substance included in human skin.
[0016] In one embodiment of the present invention, the step of setting the at least one region of interest may comprise setting a plurality of regions of interest on a human face, and the step of determining the UV coverage may comprise determining the UV coverages in the plurality of regions of interest at the same time.
[0017] In one embodiment of the present invention, the light for irradiating the target may have a wavelength in the ultraviolet light range.
[0018] A device for determining a UV coverage of a UV protection product according to one embodiment of the present invention comprises: a light source for irradiating a target with light; a detector for obtaining images of the target in response to irradiating the target with light; and a controller for determining a UV coverage of a UV protection product applied onto the target based on the images of the target obtained by the detector, wherein the controller is configured to set at least one region of interest on the target in the images, and wherein the controller is configured to determine the UV coverage of the UV protection product by comparing intensities of the detected light in the regions of interest in an image of the target before applying the UV protection product onto the target, an image of the target after applying the UV protection product onto the target, and an image of the target after applying a stress to the target onto which the UV protection product is applied.
[0019] In one embodiment of the present invention, the image of the target after applying the stress to the target onto which the UV protection product is applied may be obtained one or more times.
[0020] In one embodiment of the present invention, the controller may be configured to determine the UV coverage of the UV protection product based on the following equation:
UV Coverage [ 100
Figure imgf000006_0001
where To represents the intensity of the detected light obtained from the image of the target before applying the UV protection product onto the target, Timm represents the intensity of the detected light obtained from the image of the target after applying the UV protection product onto the target, Ti represents the intensity of the detected light obtained from the image of the target after applying an ith stress to the target onto which the UV protection product is applied, and i represents an integer larger than or equal to 1.
[0021] In one embodiment of the present invention, the detector may be configured to obtain an image of fluorescent light emitted from the target in response to irradiating the target with light.
[0022] In one embodiment of the present invention, the detector may comprise a filter configured to reduce or block fluorescent light having a wavelength other than a range between 420 and 520 nm by filtering.
[0023] In one embodiment of the present invention, the target may be a human face or a dummy sample including a fluorescent substance similar to a fluorescent substance included in human skin.
[0024] In one embodiment of the present invention, the at least one region of interest may be a plurality of regions of interest on a human face, and the controller may be configured to determine the UV coverage in the plurality of regions of interest at the same time.
[0025] In one embodiment of the present invention, the light source may be configured to irradiate the target with light having a wavelength in the ultraviolet light range.
Effect of the Invention
[0026] According to the present invention, a method and device for determining a UV coverage of a UV protection product are provided.
Brief Descriptions of Figures
[0027] Figure 1 shows a schematic view of a device for determining the UV coverage of a UV protection product according to some embodiments of the present invention. [0028] Figure 2 schematically shows a flow chart of a method of determining the UV coverage of a UV protection product according to some embodiments of the present invention.
[0029] Figure 3A shows an illumination spectrum of a Visis UV light having a range from 290 nm to 420 nm.
[0030] Figure 3B shows intensities in R, G, and B channels of fluorescent light emitted from human skin in response to UV light irradiation in the method of determining the UV coverage of a UV protection product according to some embodiments of the present invention.
[0031 ] Figure 4 shows images of the fluorescent light obtained in R, G, and B channels in the method of determining the UV coverage of a UV protection product according to some embodiments of the present invention.
[0032] Figure 5 shows an example of setting regions of interest on the target in the method of determining the UV coverage of a UV protection product according to some embodiments of the present invention.
[0033] Figure 6 shows UV coverages obtained by the method of determining the UV coverage of a UV protection product according to some embodiments of the present invention.
[0034] Figure 7 shows changes of fluorescent light obtained by a conventional method for comparison.
[0035] Figure 8 shows a correlation relationship between the UV coverages obtained by the method according to some embodiments of the present invention and the changes of fluorescent light obtained by the conventional method.
[0036] Figure 9 shows UV coverages obtained for different kinds of UV protection products by the method of determining the UV coverage of the UV protection product according to some embodiments of the present invention.
[0037] Figure 10 shows a conventional method of measuring the intensity of fluorescent light emitted from a target in response to irradiating the target with UV light.
Embodiments
[0038] A device 1 for determining an ultraviolet light coverage (UV coverage) according to some embodiments of the present invention may comprise: a light source 2 for irradiating a target 10 with light 16; a detector 6 for obtaining an image of the target 10 in response to irradiating the target 10 with the light 16; and a controller 8 for determining the UV coverage of an ultraviolet light protection product (UV protection product) 12 applied on the target 10 based on the image obtained by the detector 6 as shown in Figure 1.
[0039] The light source 2 may emit the light 16 including ultraviolet light (UV light). The light source 2 may be a known light source, for example, a mercury light or an LED. For example, the light source 2 may emit light having a wavelength in a wide range including UV light, visible light, and infrared light. In this case, the light source 2 may comprise an optional filter 22 to transmit only light having a desirable wavelength range. Such a filter 22 may allow light having a wavelength in, for example, the UV light range, to pass through. For example, the filter 22 may allow UV light, for example, light having a UVA or UV-B wavelength, or in particular, UV light including a wavelength of 365 nm, to pass through. Alternatively, the light source 2 may emit only UV light. For example, the light source 2 may emit monochromatic UV light, for example, light having a UVA or UV-B wavelength. Alternatively, in particular, the light source 2 may be a UV LED emitting UV light including a wavelength of 365 nm. If the light source 2 emits only UV light, the light source 2 does not have to comprise the filter 22.
[0040] The target 10 may be, for example, human skin, in particular, a human face. The human skin may include at least one fluorescent substance which may emit fluorescent light 20 in, for example, the visible light range in response to irradiation of light, in particular, irradiation of UV light. Such a fluorescent substance may be, for example, collagen, NADPH, or an amino acid. Alternatively, the target 10 may be a dummy sample including a fluorescent substance similar to the fluorescent substance included in the human skin. Such a dummy sample may be, for example, a pig’s skin, cultivated human skin, or a gel modeling human skin.
[0041] The UV protection product 12 applied onto the target 10 may be, for example, sunscreen. The UV protection product 12 may include a material absorbing and/or reflecting UV light. Since a part of the light 16 affecting the target 10 is blocked by the UV protection product 12, the intensity of the light 16 affecting the target 10 depends on the amount of the UV protection product 12 applied onto and remaining on the target 10. Since the intensity of the fluorescent light 20 emitted from the target 10 also depends on the intensity of the light 16 incident on the target 10, the intensity of the fluorescent light 20 emitted from the target 10 and affecting the detector 6 also depends on the amount of the UV protection product 12.
[0042] The detector 6 may detect the intensity of the fluorescent light 20 emitted from the target 10 in response to the irradiation of the light 16 and generate a signal depending on the intensity. Alternatively, the detector 6 may detect a two- dimensional distribution of the intensity of the detected fluorescent light 20 to generate a two-dimensional image having a distribution of brightness corresponding to the intensity of the fluorescent light 20. Such a detector 6 may be a known photodetector having photosensitive elements arranged in an array. The detector 6 may be, for example, a CMOS camera or a CCD camera. The intensity of the light 16 reflected on the target 10 is generally much larger than the intensity of the fluorescent light 20. Therefore, the reflected light 16 incident on the detector 6 may cause large noise, and accurate measurement of the intensity of the fluorescent light 20 may become difficult. Furthermore, if the light 16 incident on the detector 6 has a large intensity, the detector 6 may be damaged. Therefore, the detector 6 may comprise a shield 26 for blocking the light 16 reflected on the target 10. Furthermore, the detector 6 may detect fluorescent light 20 having only a wavelength in a range desirable for determining the UV coverage. For example, the detector 6 may have relatively small sensitivity, or more preferably, no sensitivity to light having a wavelength other than the desirable wavelength range. Alternatively, the detector 6 may comprise a filter 24 at least reducing, preferably blocking, the fluorescent light 20 having a wavelength other than the preferable wavelength range. The filter 24 may be configured to reduce or block fluorescent light of a wavelength other than between 290 and 420 nm by filtering. The filter 24 may also comprise a function of blocking the light 16 reflected on the target 10.
[0043] The controller 8 may be configured to control the emission of the light 16 from the light source 2, the detection of the fluorescent light 20 emitted from the target 10 by the detector 6, and the generation of the image. The controller 8 may also be configured to determine the UV coverage of the UV protection product from the images obtained by the detector 6. The determination of the UV coverage of the UV protection product will be described in detail below.
[0044] Figure 2 is a flow chart schematically showing a method 100 of determining a UV coverage of a UV protection product using the device 1.
[0045] The method 100 comprises a measurement process including steps 102 to 116. In step 102, a target 10 before applying a UV protection product 12 thereon is irradiated with the light 16, and fluorescent light 20 emitted from the target 10 is detected to obtain a first image of the target 10.
[0046] In step 104, a predetermined amount of the UV protection product 12 is applied onto the target 10.
[0047] In step 106, the target 10 is irradiated with the light 16, and the fluorescent 20 emitted from the target 10 is detected to obtain a second image of the target 10. [0048] In step 108, a predetermined stress is applied to the target 10 onto which the UV protection product 12 is applied. For example, as a stress, water may be sprayed on the target 10 and then the target 10 may be wiped with a dry cloth. If the target 10 is a human face, the subject may do an exercise such as running or riding a bike and then wipe sweat. The stress may also be the mere passage of time. Stress may also be a daily activity such as work or household chores.
[0049] In step 110, the target 10 is irradiated with light 16 and the fluorescent light 20 emitted from the target 10 is detected to obtain an image of the target 10 after applying the stress.
[0050] Steps 108 and 110 may be carried out one or more times, for example, i times (i is an integer equal to or larger l) as needed, and images may be obtained a plurality of times. If step 108 is carried out a plurality of times, step 110 may be carried out for each step 108. Step 110 may be omitted after carrying out step 108 several times. In other words, step 110 may be carried out once after repeating step 108 a predetermined number of times. A set carrying out step 110 once after repeating step 108 predetermined times may be carried out a predetermined number of times. The image obtained in step 110 after carrying out step 108 i times is referred to as the image after the ith stress. If step 110 is carried out after each step 108, the number of the obtained images is i. In case of omitting the step 110, fewer than i images are obtained.
[0051] The positions of the target 10 in the images obtained in steps 102, 106, and 110 are preferably at least similar throughout all of the images, more preferably, identical. Furthermore, the images are preferably obtained from at least similar directions, more preferably, from the same directions. Therefore, in order to make the position of the target 10 in the image match the direction of the image when obtaining the image in the step after step 106 with the first image obtained in step 102, a step of adjusting the position and the direction of the detector 6 may be carried out before obtaining the image. Such an adjustment may be carried out by an input of an operator, or may be automatically carried out by the controller 6 based on the comparison with the first image. The adjustment by the operator may be carried out with or without the controller 6.
[0052] In step 112, at least one region of interest is set on the target 10 in the images obtained from the image obtaining steps. The region of interest may preferably be a common position throughout all of the images. If the target 10 is, for example, a human face, the regions of interest may be set on, for example, the forehead, the right cheek, and the left cheek. If the images have been adjusted such that the positions of the target in the images are similar or identical, the regions of interest may be set at common positions without any need of fine adjustment of the positions for all of the images only if the regions of interest are set for one image. For example, the controller 6 may set the regions of interest. The number, positions, and sizes of the regions of interest may be appropriately set with respect to the purpose of measurement. Setting a plurality of regions of interest may result in obtaining the distribution of the applied UV protection product 12 applied onto the target 10.
[0053] In step 114, intensities of the detected light in the regions of interest set in the images are obtained. The intensity of the detected light may correspond to the brightness in the region of interest, in other words, the gray scale value. Therefore, the gray scale value may be employed as an indicator representing the intensity of the detected light. The gray scale value may be obtained by, for example, averaging the gray scale values of the pixels in the region of interest.
[0054] In step 116, the UV coverage of the UV protection product 12 may be determined by comparing the intensities of the detected light, for example, the gray scale values in the regions of interest of the images in the image obtaining steps. Various ways may be provided for determining the UV coverage. Preferably, the UV coverage is defined by the following equation:
Ti - Tt mm
UV Coverage [%] 1 - x 100
T0 - Tt i mm where To is the intensity of the detected light obtained from the first image of the target 10 before applying the UV protection product 12 thereon, Timm is the intensity of the detected light obtained from the second image of the target 10 after applying the UV protection product 12 thereon, and Ti is the intensity of the detected light obtained from the image after the ith stress obtained after applying the ith stress to the target 10 onto which the UV protection product 12 is applied. The gray scale values in the regions of interest in the images may be used as the intensities of the detected light as discussed above.
[0055] The detector 6 may preferably detect light in the blue range among the fluorescent light 20. For example, if the detector 6 is a conventional CMOS camera or CCD camera having R, G, and B channels, images may preferably be obtained by using only the data of the B channel. Figure 3A shows an illumination spectrum of a Visis UV light having a peak at 365.9 nm and a range from 290 to 420 nm. Figure 3B shows the intensities of fluorescent light in the R, G, and B channels, which is emitted from human skin in response to the irradiation of UV light. It is shown that the intensity in the B channel is highest. Figure 4 shows images of fluorescent light in the R, G, and B channels emitted from a human face in response to the irradiation of UV light. It is shown that the image of the B channel has the largest brightness and the highest contrast. Therefore, when the data in the B channel is used, the UV coverage may be determined with a high resolution and a high accuracy.
Furthermore, the detector 6 may comprise a filter 24 for reducing or blocking light having a wavelength other than the B channel wavelength. The filter 24 may reduce or block light having a wavelength other than the range between 290 and 420 nm. [0056] In order to compare the device 1 and the method 100 with the conventional method shown in Figure 10, the UV coverage and the change of the intensity of the fluorescent light were determined by the following procedure.
[0057] First, preliminary preparations were carried out. A subject washed the face with a cleansing oil and a foaming cleanser. Thereafter, 1.0 mL of cosmetic water and 0.6 mL of milky lotion were applied onto the entire face to moisturize it. Acclimation was then carried out at 22°C and 45% humidity for 15 minutes.
[0058] The measurement was then carried out before applying a UV protection product. In particular, the subject’s face was irradiated with UV light by using the device 1, and a first image was obtained based on fluorescent light emitted from the face. Furthermore, the left and right sides of the forehead and the left and right cheeks were irradiated with UV light and the intensities of the emitted fluorescent light were measured by the conventional method.
[0059] After the measurement, 150 mg of two types of UV protection products (858419 5) and (884474 l)) were applied onto the left and right sides of the face, respectively. The acclimation was then carried out at 22°C and 45% humidity for 15 minutes.
[0060] The measurement was then carried out after applying the UV protection products. Specifically, the second image was obtained by using the device 1. The intensities of the fluorescent light were also measured by the conventional method. [0061] Next, the subject had a light meal in an environment at 22°C and 45% humidity within 30 minutes. After the meal, an operator sprayed 2.5 g of water mist on the entire face for 3 seconds from a distance of 20 cm as the first stress. A paper towel was then put on the entire face to remove moisture.
[0062] The measurement then was carried out after the first stress. Specifically, the image after the first stress was obtained by using the device 1. The intensities of the fluorescent light were also measured by the conventional method.
[0063] As the second stress, the subject spent 40 minutes in an environment at 30 to 32°C and 30% of humidity, and performed an exercise on a fitness bike in an environment of 20 to 30°C and 30% humidity for tern minutes. During the exercise, the subject was requested to maintain the heart rate at 130 beats/minute. Next, a paper towel was put on the entire face to remove sweat. The acclimation was carried out at 22°C and 45% humidity for 30 minutes.
[0064] The measurement was then carried out after the second stress. Specifically, the image after the second stress was obtained by using the device 1. The intensities of the fluorescent light were also measured by the conventional method.
[0065] As the third stress, the operator wiped each surface of the subject’s face twice with dry cotton.
[0066] Next, the measurement was carried out after the third stress. Specifically, the image after the third stress was obtained by using the device 1. The intensities of the fluorescent light were also measured by the conventional method.
[0067] Thereafter, regions of interest were set on the left and right sides of the forehead and left and right cheeks by using the device 1 as shown in Figure 5. The regions of interest were set such that the regions where the intensities of fluorescent light were measured by the conventional method were included in the regions of interest. The gray scale values of the regions of interest were determined by averaging the gray scale values in the regions of interest in the images.
[0068] The UV coverage after the ith stress was applied was then determined using the following equation based on the gray scale values in the regions of interest of the images:
Ti - 7 i mm
UV Coverage [%] 1 - X 100
T0 - mm where To is the gray scale value obtained from the first image of the subject’s face before applying the UV protection products thereon, Timm is the gray scale value obtained from the second image of the subject’s face after applying the UV protection products thereon, and Ti is the gray scale value obtained from the image after the ith stress was applied to the subject’s face onto which the UV protection product was applied. As discussed above, the gray scale values correspond to the intensities of the fluorescent light emitted from the subject’s face and detected.
[0069] Similarly, the change of fluorescent light obtained by the conventional method after the ith stress was determined by the following equation: 100
Figure imgf000014_0001
where Timm is the intensity of the fluorescent light from the subject’s face which was measured based on the conventional method after applying the UV protection products onto the subject’s face, and Ti is the intensity of the fluorescent light which was measured based on the conventional method after applying the ith stress to the subject’s face onto which the UV coverage was applied.
[0070] Figure 6 shows the UV coverage obtained by the method of the present invention. It can be seen that the UV coverage decreases for each application of stress regarding the two types of UV protection products (858419 5) and (884474 l) which were applied onto the forehead and cheeks.
[0071] Figure 7 shows the change of the intensity of the fluorescent light obtained by the conventional method shown in Figure 10 for comparison. It can be seen that the intensity of the fluorescent light increases for each application of stress regarding the two types of UV protection products (858419 5) and (884474 l) which were applied onto the forehead and cheeks.
[0072] Figure 8 shows the correlation relationship between the UV coverage obtained by the method of the present invention and the change of the intensity of the fluorescent light obtained by the conventional method. The UV coverage exhibits a good correlation with the change of the intensity of the fluorescent light, and therefore it can be seen that the UV protection effect of a UV protection product can be evaluated by measuring the UV coverage instead of the change of the intensity of the fluorescent light. Different from the conventional method, since the method of the present invention can obtain UV coverages at a plurality of portions in an image of a target at the same time, the UV protection effect of a UV protection product at a plurality of portions in the target can be evaluated at the same time, and the distribution of the UV protection product can be also evaluated.
[0073] Furthermore, Figure 9 shows the UV coverages obtained by the method of the present invention for two types of UV protection products (858419 5) and (884474 l). Figure 9 shows that (884474 1) has a higher resistance for stresses than (858419 5). Since the method of the present invention can evaluate UV coverages of a plurality of types of UV protection products applied on different portions on a target, different types of UV protection products can be easily and accurately compared.
[0074] Although specific embodiments of the present invention were described, those skilled in the art would easily understand that various changes, modifications and improvements are possible without departing from the technical spirit and scope of the present invention.
Designations
1. Device for determining the UV coverage
2. Light source 6. Detector
8. Controller 10. Target
12. UV protection product 16: Light
20. Fluorescent light 22. Filter of the light source 24. Filter of the detector
26. Shield
1006. Optical sensor
1010. Target
1016. Light
1020. Fluorescent light

Claims

Claims
1. A method of determining a UV coverage of a UV protection product by a measurement process comprising the steps of obtaining an image of a target by irradiating the target with light before applying a UV protection product onto the target; obtaining an image of the target by irradiating the target with light after applying the UV protection product onto the target; obtaining an image of the target by irradiating the target with light after applying a stress to the target onto which the UV protection product is applied; setting at least one region of interest on the target in the image obtained in each image obtaining step; obtaining intensities of detected light in the regions of interest in the images obtained from the image obtaining steps; and determining a UV coverage of the UV protection product by comparing the intensities of the detected light in the regions of interest in the images obtained from the image obtaining steps.
2. The method of Claim 1, wherein the step of obtaining the image of the target by irradiating the target with light after applying the stress to the target onto which the UV protection product is applied is carried out one or more times.
3. The method of Claim 1, wherein the step of determining the UV coverage of the UV protection product determines the UV coverage of the UV protection product based on the following equation:
Ά - TL mm
UV Coverage [%] = 1 x 100
To - Ti mmJ where To represents an intensity of the detected light obtained from the image of the target before applying the UV protection product, Timm represents an intensity of the detected light obtained from the image of the target after applying the UV protection product onto the target, Ti represents an intensity of the detected light obtained from the image of the target after applying an ith stress to the target onto which the UV protection product is applied, and i represents an integer equal to or larger than 1.
4. The method of Claim 1, wherein the steps of obtaining the image of the target comprise obtaining an image of fluorescent light emitted from the target in response to irradiating the target with light.
5. The method of Claim 1, wherein the steps of obtaining the image of the target comprise reducing or blocking fluorescent light having a wavelength in a range other than between 290 and 420 nm by filtering.
6. The method of Claim 1, wherein the target is a human face or a dummy sample including a fluorescent substance similar to a fluorescent substance included in human skin.
7. The method of Claim 1, wherein the step of setting the at least one region of interest comprises setting a plurality of regions of interest on a human face, and wherein the step of determining the UV coverage comprises determining the UV coverages in the plurality of regions of interest at the same time.
8. The method of Claim 1, wherein the light for irradiating the target has a wavelength in the ultraviolet light range.
9. A device for determining a UV coverage of a UV protection product, comprising: a light source for irradiating a target with light; a detector for obtaining images of the target in response to irradiating the target with light; and a controller for determining a UV coverage of a UV protection product applied onto the target based on the images of the target obtained by the detector, wherein the controller is configured to set at least one region of interest on the target in the images, and wherein the controller is configured to determine the UV coverage of the UV protection product by comparing intensities of the detected light in the regions of interest in an image of the target before applying the UV protection product onto the target, an image of the target after applying the UV protection product onto the target, and an image of the target after applying a stress to the target onto which the UV protection product is applied.
10. The device of Claim 9, wherein the image of the target after applying the stress to the UV protection product applied onto the target is obtained one or more times.
11. The device of Claim 9, wherein the controller is configured to determine the UV coverage of the UV protection product based on the following equation:
UV Coverage[ 100
Figure imgf000019_0001
where To represents an intensity of the detected light obtained from the image of the target before applying the UV protection product onto the target, Timm represents an intensity of the detected light obtained from the image of the target after applying the UV protection product onto the target, Ti represents an intensity of the detected light obtained from the image of the target after applying an ith stress to the target onto which the UV protection product is applied, and i represents an integer equal to or larger than 1.
12. The device of Claim 9, wherein the detector is configured to obtain an image of fluorescent light emitted from the target in response to irradiating the target with light.
13. The device of Claim 9, wherein the detector comprises a filter configured to reduce or block fluorescent light having a wavelength in a range other than between 420 and 520 nm by filtering.
14. The device of Claim 9, wherein the target is a human face or a dummy sample including a fluorescent substance similar to a fluorescent substance included in human skin.
15. The device of Claim 9, wherein the at least one region of interest is a plurality of regions of interest on a human face, and wherein the controller is configured to determine the UV coverage in the plurality of regions of interest at the same time.
16. The device of Claim 9, wherein the light source is configured to irradiate the target with light having a wavelength in the ultraviolet light range.
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