Light source, inspection device, and inspection method

Abstract

To provide a light source that can detect a foreign substance approximate to an inspection object in optical absorption properties and light reflectance properties in a near-infrared region.SOLUTION: A solid light-emitting device emits primary light having a maximum intensity value within a wavelength range of 440 nm or more and less than 480nm. A phosphor includes a red phosphor that absorbs the primary light and emits red light having a maximum intensity value within a wavelength range of 600 nm or more and less than 660 nm, and a near-infrared phosphor that emits near-infrared light having a maximum intensity value within a wavelength range of 700 nm or more and less than 1000 nm. The spectral distribution of output light has one or two maximum values within a wavelength range of 600 nm or more and 900 nm or less. The maximum values are both within a wavelength range of 600 nm or more and 750 nm or less. For the maximum value, of the maximum values, which has the maximum spectral intensity, when the spectral intensity is defined as Pmax, the maximum value of the spectral intensity of a region having a wavelength longer than a wavelength of 750 nm is 20% of Pmax or more and less than Pmax, and the spectral intensity within a wavelength range of 500 nm or more and 550 nm or less is less than 20% of Pmax.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a light source, an inspection apparatus, and an inspection method.

Background Art

[0002] Conventionally, inspection apparatuses and inspection methods for foreign substances using white light and near-infrared light are known. Patent Document 1 discloses a detection method for detecting foreign substances contained in foods such as fruits. Specifically, first, the absorption spectra of visible light and near-infrared light of reflected light obtained by irradiating light on the food and the foreign substance are measured, second-order differential processing is performed on the absorption spectra, and a wavelength band showing different second-order differential spectra between the food and the foreign substance is selected. Subsequently, a second-order differential spectroscopic image of the selected wavelength band is created for the food. Thereby, foreign substances contained in the food are detected.

[0003] Patent Document 2 discloses a food inspection apparatus for grasping the presence or absence and the position of foreign substances contained in food. Specifically, a surface light source that irradiates first and second inspection lights having a center wavelength in the near-infrared region on the food, an imaging mechanism that outputs first and second images captured by the first and second inspection lights, and a differential image generation unit that generates a differential image of the first and second images are provided. Note that the food inspection apparatus of Patent Document 2 uses two types of superluminescent diodes (SLDs) having different wavelengths without using a phosphor as a light source.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

[0005] However, since the detection method in Patent Document 1 uses white light having light components over a wide wavelength range from short-wavelength visible light to near-infrared light, the light utilization efficiency is poor. Further, since the apparatus used in this detection method needs to emit white light having light components over a wide wavelength range, it has been difficult to make the light source small and high-output. Further, since the inspection apparatus in Patent Document 2 uses light components biased in the near-infrared region, it has been difficult to detect with high sensitivity foreign matters whose light absorption characteristics and light reflection characteristics in the near-infrared region are approximated to those of the inspection object.

[0006] The present invention has been made in view of such problems of the prior art. And an object of the present invention is to provide a light source, an inspection apparatus, and an inspection method capable of detecting foreign matters whose light absorption characteristics and light reflection characteristics in the near-infrared region are approximated to those of the inspection object.

[0007] In order to solve the above problems, a light source according to a first aspect of the present invention is a light source that combines a solid light-emitting element and a phosphor and emits output light, wherein the solid light-emitting element emits primary light having a maximum intensity within a wavelength range of 440 nm or more and less than 480 nm, and the phosphor includes a red phosphor that absorbs the primary light and emits red light having a maximum intensity within a wavelength range of 600 nm or more and less than 660 nm, and a near-infrared phosphor that emits near-infrared light having a maximum intensity within a wavelength range of 700 nm or more and less than 1000 nm. The spectral distribution of the output light has one or two maxima within a wavelength range of 600 nm or more and 900 nm or less, and all of the maxima are within a wavelength range of 600 nm or more and 750 nm or less. When the spectral intensity at the maximum value where the spectral intensity is maximum among the one or two maxima is defined as Pmax, the maximum value of the spectral intensity in the wavelength region longer than 750 nm is 20% or more and less than Pmax of the Pmax, and the spectral intensity within a wavelength range of 500 nm or more and 550 nm or less is less than 20% of the Pmax.

[0008] An inspection apparatus according to a second aspect of the present invention includes the above light source and a photodetector. The inspection method according to the third aspect of the present invention is an inspection method using the above inspection apparatus, and includes a step of irradiating an inspection object with inspection light, and a step of detecting reflected light of the inspection light reflected by the inspection object.

Brief Description of Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0010] Hereinafter, the inspection apparatus and inspection method according to the present embodiment will be described in detail with reference to the drawings. Note that the dimensional ratios in the drawings are exaggerated for convenience of explanation and may be different from the actual ratios.

[0011] [Principle of Inspection Apparatus and Inspection Method] After contaminating the object to be inspected with foreign matter, while irradiating the object to be inspected with light, the inventors investigated how foreign matter in the object to be inspected is detected by a photodetector by changing the spectral distribution of the irradiated light. Specifically, a bento was selected as the object to be inspected, and hairs with different color tones were mixed in as foreign matter. Then, while irradiating the bento with light, the spectral distribution of the irradiated light was changed, and the ingredients and hairs in the bento were imaged with a photodetector. As a result, it was found that when light having a specific spectral distribution is used, foreign matter can be detected with high sensitivity and good reproducibility regardless of the color tone of the foreign matter.

[0012] As a result of investigating the reason why foreign matter can be detected in this way, it was found that the appearance of foreign matter by the photodetector (imaging device) is related to the light reflection characteristics of the object to be inspected and the foreign matter. Also, it was found that good detection results can be obtained when the intensity of red light is strong, a certain amount of near-infrared light is included, and the spectral distribution is wide as the irradiation light.

[0013] Fig. 1 shows the results of investigating the wavelength dependence of the reflectance with respect to representative ingredients of a bento and hairs with different color tones. As the ingredients of the bento, nori seaweed, chicken karaage, broccoli, omelette, and rice were used. Also, as the hairs, black hair, brown hair, and white hair were used.

[0014] As shown in Fig. 1, it can be seen that many ingredients with dark color tones, such as nori seaweed, broccoli, and chicken karaage, lower their reflectance as the wavelength shortens from the near-infrared region to the red light region. Also, it can be seen that black hair and brown hair also lower their reflectance as the wavelength shortens from the near-infrared region. However, it can be seen that omelette, rice, and white hair are less likely to have their reflectance decreased even when the wavelength shortens from the near-infrared region to the red light region.

[0015] That is, it can be seen that the wavelength dependence of the reflectance spectra of the food ingredients and hair becomes significantly different within the wavelength range of 550 nm or more and 750 nm or less, particularly within the wavelength range of 600 nm or more and 700 nm or less. Specifically, nori, broccoli, and black hair have a significant decrease in reflectance within this wavelength range, while fried chicken and brown hair have a smaller decrease in reflectance than nori, broccoli, and black hair. Conversely, tamagoyaki, rice, and white hair do not have a significant decrease in reflectance within this wavelength range. Therefore, it can be seen that foreign objects can be detected by utilizing the difference in the reflectance of red light. For example, when black hair or brown hair is mixed into the surface of rice and tamagoyaki, the black hair and brown hair can be discovered by irradiating red light and detecting the reflected light, thereby utilizing the difference in reflectance.

[0016] However, when the intensity of the red light contained in the irradiation light is low, even if the reflected light is detected by a photodetector, the S / N (signal-to-noise ratio) deteriorates, and the red light cannot be accurately detected. Therefore, by irradiating the inspection object with strong red light, the signal intensity of the red light detected by the photodetector increases, the S / N is improved, and the difference in signal intensity between the inspection object and the foreign object becomes clear.

[0017] Thus, there are many combinations in which the wavelength dependence of the reflectance spectra of the bento ingredients and hair becomes significantly different within the wavelength range of 550 nm or more and 750 nm or less, particularly within the wavelength range of 600 nm or more and 700 nm or less. Therefore, when the intensity of the light component within this wavelength range is high, it is considered to be effective in detecting hair as a foreign object.

[0018] Here, as shown in FIG. 1, since nori, broccoli, and black hair have a dark color tone, within the wavelength range of 600 nm or more and 700 nm or less, the behavior of the reflected light is almost the same. Therefore, when red light is used as the irradiation light, it is difficult to discover black hair even if black hair is mixed into the surface of nori and broccoli.

[0019] However, black hair has the property of easily absorbing near-infrared light and hardly reflecting it. That is, when comparing the reflectance of black hair and the ingredients of the bento, within the wavelength range of at least 750 nm to 900 nm, almost all of the ingredients exhibit a relatively high reflectance of about 50% or more, while the reflectance of black hair is less than 20%, and the difference is significant. Therefore, it can be seen that black hair in the ingredients can be detected with high sensitivity by the reflected light of near-infrared light.

[0020] Here, as shown in FIG. 1, the reflectance of brown hair and white hair within the wavelength range of 750 nm to 900 nm is equivalent to that of the ingredients. Therefore, it is difficult to detect brown hair and white hair from the ingredients using near-infrared light. However, as described above, the reflectance of brown hair and white hair within the wavelength range of 550 nm to 750 nm has a certain difference from the reflectance of the ingredients. Therefore, it can be seen that brown hair and white hair in the ingredients can be detected with high sensitivity by the reflected light of red light.

[0021] In this way, strong red light is effective in detecting brown hair and white hair and improving their signal-to-noise ratio, and near-infrared light is effective in detecting black hair. Therefore, by using light containing a near-infrared light component and a strong red light component as the inspection light, it becomes possible to detect foreign substances with high sensitivity regardless of the color tone.

[0022] The inspection apparatus and inspection method of the present embodiment are made based on such findings, and are characterized by using light that is particularly convenient for detecting hair mixed in the ingredients of the bento. In addition to detecting hair mixed in the ingredients of the bento, it is possible to apply the inspection apparatus and inspection method of the present embodiment. That is, considering that both the ingredients and the hair can be regarded as organic substances, and that the ingredients are food and the hair is not food, it can also be applied to the detection of other organic foreign substances contained in specific organic substances, and the detection of organic foreign substances contained in foods and consumer products. Therefore, the inspection apparatus and inspection method of the present embodiment are not limited to the inspection of hair contained in the ingredients of the bento, and can also be used for other inspections.

[0023] [Configuration of the inspection device] In FIG. 2, the configuration of the inspection device according to this embodiment is schematically shown. The inspection device 100 of this embodiment includes at least a light source 10 provided with a phosphor and a photodetector 20. Then, after irradiating the inspection object 30 with the inspection light 11 emitted from the light source 10, the photodetector 20 detects the reflected light 12 of the inspection light 11 reflected by the inspection object 30.

[0024] In such an inspection device 100, the inspection light 11 emitted from the light source 10 has, for example, the spectral distribution shown in FIG. 3 or FIG. 4. Specifically, the spectral distribution of the inspection light 11 has at least one maximum value 11A, 11B derived from the fluorescence emitted by the phosphor. And at least the maximum value 11A is preferably within the wavelength range of 600 nm or more and 750 nm or less, more preferably within the wavelength range of 610 nm or more and 700 nm or less, and even more preferably within the wavelength range of 620 nm or more and 680 nm or less.

[0025] When the spectral intensity of the maximum value 11A where the spectral intensity is maximum among at least one maximum value 11A, 11B is defined as Pmax, the maximum value of the spectral intensity in the wavelength range longer than 750 nm is preferably 20% or more and less than Pmax of Pmax. Also, the maximum value of the spectral intensity in the wavelength range longer than 750 nm is more preferably 30% or more and less than 80% of Pmax, and even more preferably 50% or more and less than 70% of Pmax. And the spectral intensity within the wavelength range of 500 nm or more and 550 nm or less is preferably less than 20% of Pmax, more preferably less than 18% of Pmax, and even more preferably less than 16% of Pmax.

[0026] As described above, by using light including a near-infrared light component and a strong red light component as the inspection light 11, foreign matters can be detected with high sensitivity. Then, as shown in FIGS. 3 and 4, the inspection light 11 has red light having a maximum value in a wavelength range of 600 nm or more and 750 nm or less, and near-infrared light in a wavelength region longer than 750 nm. Further, the spectral intensity of the red light is larger than the spectral intensity of the near-infrared light. In this way, since the inspection light 11 uses light including both red and near-infrared light components having a wavelength difference, even similar foreign matters (for example, hairs having different color tones) that are difficult to detect only with near-infrared light can be detected with red light. Therefore, the detection probability of foreign matters increases, and it becomes possible to improve the inspection accuracy. Furthermore, since light with a strong intensity of red light is irradiated onto the inspection object 30 together with the near-infrared light, the inspection accuracy of the inspection object and foreign matters having a lower reflectance in the red wavelength region than in the near-infrared region becomes higher.

[0027] Further, the inspection light 11 has a spectral intensity within a wavelength range of 500 nm or more and 550 nm or less of less than 20% of Pmax. That is, while increasing the intensity of the red light, the inspection light 11 decreases the intensity of the green light. As a result, the light components are concentrated in a specific wavelength region for determining the quality of the inspection, so that the utilization efficiency of light and the electro-optical conversion efficiency of the light source 10 can be increased. As a result, the inspection apparatus 100 is advantageous for miniaturization and high output and high efficiency.

[0028] In this way, the inspection apparatus 100 can accurately detect similar foreign matters that are difficult to detect only with near-infrared light by using both near-infrared light and red light, and can further reduce the size of the apparatus.

[0029] In the spectral distribution of the inspection device 100, the number of maxima 11A and 11B within the wavelength range of 500 nm or more and 1000 nm or less is preferably one or two. Further, it is more preferable that the number of maxima 11A and 11B within the wavelength range of 600 nm or more and 900 nm or less is one or two. Also, the maximum 11A derived from the fluorescent component emitted by the phosphor preferably takes the maximum intensity value of the spectral distribution. By doing so, the inspection light 11 becomes light in which the light components are concentrated in the red to near-infrared wavelength region that determines the quality of the inspection. Therefore, since it becomes easy to design a light source with high electro-optical conversion efficiency and the inspection light 11 with high utilization efficiency, it is advantageous for miniaturization and high output of the light source 10 and compactification of the inspection device 100.

[0030] Regarding the spectral distribution of the inspection device 100, in the spectral intensity within the wavelength range of 550 nm or more and 850 nm or less, the amount of change with respect to the wavelength is preferably less than 5% per 1 nm of wavelength. Further, in the spectral intensity within the wavelength range of 550 nm or more and 950 nm or less, the amount of change with respect to the wavelength is more preferably less than 5% per 1 nm of wavelength. By making the spectral distribution derived from the fluorescent component emitted by the phosphor wide in this way, the intensity change with respect to the wavelength is small, and furthermore, it has light components within all the above wavelength ranges. Therefore, even when the inspection object 30 has a large wavelength dependence of the light reflection characteristic or the light absorption characteristic, it becomes possible to inspect with relatively high accuracy.

[0031] (Light source) The light source 10 of the inspection device 100 is preferably composed of a combination of a solid-state light-emitting element 3 and a phosphor. The wavelength-converting light-emitting element combining the solid-state light-emitting element 3 and the phosphor is a full-solid-state light source with a long lifespan, excellent reliability, and easy circuit design. By using such a wavelength-converting light-emitting element, it becomes possible to reduce the burden of inspection and maintenance of the light source over a long period.

[0032] More specifically, as shown in FIGS. 2 and 5, the light source 10 includes a solid-state light-emitting element 3, a first wavelength converter 1A including a red phosphor that emits first wavelength-converted light 1B, and a second wavelength converter 2A including a near-infrared phosphor that emits second wavelength-converted light 2B. The solid-state light-emitting element 3 emits primary light 3B. The first wavelength converter 1A absorbs at least a part of the primary light 3B and converts it into first wavelength-converted light 1B mainly including a red light component. The second wavelength converter 2A absorbs a part of the primary light 3B and converts it into second wavelength-converted light 2B mainly including a near-infrared light component.

[0033] Specifically, the first wavelength converter 1A receives the primary light 3B at the front surface 1Aa and emits the primary light 3B and the first wavelength-converted light 1B from the back surface 1Ab. Further, the second wavelength converter 2A receives the primary light 3B at the front surface 2Aa and emits the primary light 3B and the second wavelength-converted light 2B from the back surface 2Ab. Then, the mixed light (inspection light 11) of the first wavelength-converted light 1B, the second wavelength-converted light 2B, and the primary light 3B is output from the output surface 10a of the light source 10.

[0034] As shown in FIG. 2, the light source 10 can be configured such that the first wavelength converter 1A and the second wavelength converter 2A are arranged in parallel along the light output surface of one solid-state light-emitting element 3. Further, as shown in FIG. 5, the light source 10 can also be configured such that a first wavelength-converted light-emitting element combining the solid-state light-emitting element 3 and the first wavelength converter 1A and a second wavelength-converted light-emitting element combining the solid-state light-emitting element 3 and the second wavelength converter 2A are arranged in parallel.

[0035] Further, the light source 10 can also be configured by combining the solid-state light-emitting element 3 and a laminate of a plurality of wavelength converters. At this time, the laminate can be configured by laminating a first wavelength converter 1A containing a red phosphor and a second wavelength converter 2A containing a near-infrared phosphor. The first wavelength converter 1A absorbs at least a part of the primary light 3B and converts it into first wavelength-converted light 1B. Also, the second wavelength converter 2A also absorbs at least a part of the primary light 3B and converts it into second wavelength-converted light 2B. Then, the laminate receives the primary light 3B on the front surface and emits the primary light 3B, the first wavelength-converted light 1B, and the second wavelength-converted light 2B from the back surface. Note that the second wavelength converter 2A can also be configured to exclusively absorb the first wavelength-converted light 1B emitted by the first wavelength converter 1A and emit the second wavelength-converted light 2B.

[0036] In addition, the light source 10 can be configured by combining the solid-state light-emitting element 3 and a single wavelength converter, and the wavelength converter can be configured to contain both a red phosphor and a near-infrared phosphor. In this case, the wavelength converter absorbs at least a part of the primary light 3B and converts it into first wavelength-converted light 1B and second wavelength-converted light 2B. Then, the wavelength converter receives the primary light 3B on the front surface and emits the primary light 3B, the first wavelength-converted light 1B, and the second wavelength-converted light 2B from the back surface.

[0037] <Solid-state light-emitting element> In the light source 10, the solid-state light-emitting element 3 preferably emits light having a maximum intensity value within a wavelength range of 440 nm or more and less than 480 nm. Specifically, the solid-state light-emitting element 3 is preferably a blue light-emitting element that emits light having a maximum intensity value within a wavelength range of 440 nm or more and less than 480 nm, particularly 445 nm or more and less than 470 nm. With such a configuration, the light emitted by the solid-state light-emitting element 3 becomes light having a shorter wavelength than the maximum value formed from the fluorescent component emitted by the phosphor. Therefore, by irradiating the phosphor with the blue light emitted by the solid-state light-emitting element 3, light components of red and near-infrared can be easily obtained as the wavelength-converted light of the phosphor. Also, since the solid-state light-emitting element 3 that emits blue light is easily available, the inspection apparatus 100 is advantageous for industrial production.

[0038] The solid-state light-emitting element 3 is preferably a light-emitting diode or a laser diode. Also, by using an LED module or a laser diode that emits high-energy light of 1 W or more as the solid-state light-emitting element 3, the inspection apparatus 100 can expect a light output including a near-infrared light component in the order of several hundred mW. By using an LED module that emits light of 3 W or more or 10 W or more as the solid-state light-emitting element 3, the inspection apparatus 100 can expect a light output in the order of several W. By using an LED module that emits light of 30 W or more as the solid-state light-emitting element 3, the inspection apparatus 100 can expect a light output exceeding 10 W. By using an LED module that emits light of 100 W or more as the solid-state light-emitting element 3, the inspection apparatus 100 can expect a light output exceeding 30 W. Note that as the laser diode, for example, an edge-emitting laser (EEL) or a vertical cavity surface-emitting laser (VCSEL) can be used.

[0039] Preferably, there are a plurality of solid-state light-emitting elements 3. Thereby, the output of the primary light 3B can be increased, and the inspection apparatus is advantageous for high output. Note that the number of solid-state light-emitting elements is not particularly limited, and can be, for example, 9 or more, 16 or more, 25 or more, 36 or more, 49 or more, 64 or more, 81 or more, or 100 or more. Also, the upper limit of the number of solid-state light-emitting elements is not particularly limited, and can be, for example, 9, 16, 25, 36, 49, 64, 81, or 100.

[0040] In the inspection apparatus 100, the solid-state light-emitting element 3 is preferably a surface-emitting type surface light source. Thereby, variations in the intensity distribution and color tone unevenness of the primary light 3B are suppressed, and the inspection apparatus is advantageous for suppressing intensity unevenness of the output light.

[0041] The light energy density of the primary light 3B emitted by the solid-state light-emitting element 3 preferably exceeds 0.3 W / mm 2 and preferably exceeds 1.0 W / mm 2It is more preferable that it exceeds this. By doing so, since the light energy density of the primary light 3B is large, when configured to irradiate the diffused primary light 3B onto the first wavelength converter 1A and the second wavelength converter 2A, a relatively strong inspection light 11 can be emitted. Also, when configured to directly irradiate the non-diffused primary light 3B onto the first wavelength converter 1A and the second wavelength converter 2A, an inspection light 11 with a large light energy density can be emitted. Note that the upper limit of the light energy density of the primary light 3B emitted by the solid light-emitting element 3 is not particularly limited, but for example, it can be 30 W / mm 2 can be set as such.

[0042] <First wavelength converter> The first wavelength converter 1A can be a wavelength converter in which a red phosphor is encapsulated with a silicone resin. Also, the first wavelength converter 1A can be an all-inorganic wavelength converter in which a red phosphor is encapsulated with a low-melting-point glass. Furthermore, the first wavelength converter 1A can also be an all-inorganic wavelength converter mainly composed of a red phosphor using a binder or the like. The first wavelength converter 1A can also be a sintered body obtained by sintering a red phosphor, that is, a fluorescent ceramic.

[0043] The thickness of the first wavelength converter 1A is not particularly limited, but it is preferably such that the maximum thickness is 100 μm or more and less than 5 mm, and more preferably 200 μm or more and less than 1 mm.

[0044] The first wavelength converter 1A preferably has translucency. Thereby, the primary light 3B and the light component wavelength-converted inside the wavelength converter can be emitted through the first wavelength converter 1A.

[0045] The red phosphor contained in the first wavelength converter 1A is a phosphor that absorbs the primary light 3B and converts it into the first wavelength-converted light 1B. The red phosphor preferably emits red light having a maximum intensity within a wavelength range of 600 nm or more and less than 660 nm, and more preferably emits red light having a maximum intensity within a wavelength range of 610 nm or more and less than 650 nm. By doing so, the primary light 3B emitted by the solid light-emitting element 3 can be easily wavelength-converted into a red light component, which is advantageous for obtaining the red light component required for the inspection light 11.

[0046] As the red phosphor, a phosphor activated by at least one of a rare earth ion and a transition metal ion and emitting red light can be used. The rare earth ion is preferably at least one of Ce 3+ and Eu 2+ . The transition metal ion is preferably Mn 4+ . The red phosphor is preferably an oxide, sulfide, nitride, halide, oxysulfide, oxynitride, or oxyhalide containing the fluorescent ion.

[0047] The red phosphor is more preferably an oxide, sulfide, nitride, halide, oxysulfide, oxynitride, or oxyhalide containing Eu 2+ as a luminescence center. Further, the red phosphor is preferably a phosphor composed of a metal composite nitride or a metal composite oxynitride activated by Eu 2+ . Examples of such Eu 2+ -activated nitride-based phosphors include alkaline earth metal silicon oxynitrides, alkaline earth metal aluminum silicon oxynitrides, alkaline earth metal silicon oxynitrides, and alkaline earth metal aluminum silicon oxynitrides. Further, examples of Eu 2+ -activated nitride-based phosphors include MAlSiN3:Eu 2+ , M2Si5N8:Eu 2+ , MAlSi4N7:Eu 2+ . Here, M is at least one element selected from the group consisting of Ca, Sr, and Ba. Furthermore, examples of Eu 2+ -activated nitride-based phosphors include Si in the crystal constituting the above compound4+ -N 3+ Part of the combination of which Al 3+ -O 2- The phosphor in which is replaced can also be mentioned.

[0048] Eu 2+ The red phosphor having Eu as a luminescence center can absorb blue light and convert it into red light with a wide spectral distribution. Further, such a red phosphor has been improved with the development of the technology of light-emitting diodes (LEDs). And since a red phosphor that can convert the absorbed blue light with a photon conversion efficiency close to the theoretical limit is commercially available for LED lighting, it is easy to procure. Therefore, by using such a red phosphor, not only the primary light 3B emitted from the solid light-emitting element 3 can be reduced, but also red light having a wide spectral distribution required for inspection can be easily obtained.

[0049] <Second wavelength converter> The second wavelength converter 2A can be a wavelength converter in which a near-infrared phosphor is encapsulated with a silicone resin. Further, the second wavelength converter 2A can be an all-inorganic wavelength converter in which a near-infrared phosphor is encapsulated with a low-melting glass. Furthermore, the second wavelength converter 2A can also be an all-inorganic wavelength converter mainly composed of a near-infrared phosphor using a binder or the like. The second wavelength converter 2A can also be a sintered body obtained by sintering a near-infrared phosphor, that is, a fluorescent ceramic. Since the shape of the second wavelength converter 2A is the same as that of the first wavelength converter 1A, duplicate explanations are omitted.

[0050] The second wavelength converter 2A preferably has translucency. Thereby, in addition to the primary light 3B, the light component wavelength-converted inside the wavelength converter can also be transmitted through the second wavelength converter 2A and emitted. Further, the second wavelength converter 2A preferably transmits light having a wavelength of 750 nm. Thereby, since the second wavelength converter 2A transmits near-infrared light, the absorption of photons by the wavelength converter itself inside the wavelength converter and the disappearance thereof are suppressed.

[0051] The near-infrared phosphor contained in the second wavelength converter 2A is a phosphor that absorbs the primary light 3B and converts it into the second wavelength-converted light 2B. The near-infrared phosphor preferably emits near-infrared light having a maximum intensity within a wavelength range of 700 nm or more and less than 1000 nm, and more preferably emits near-infrared light having a maximum intensity within a wavelength range of 720 nm or more and less than 900 nm. This facilitates wavelength conversion of the primary light 3B emitted by the solid-state light-emitting element 3 into a near-infrared light component, which is advantageous for obtaining the near-infrared light component required for the inspection light 11.

[0052] As the near-infrared phosphor, for example, various inorganic phosphors known for use as near-infrared light sources can be used. Specifically, as the near-infrared phosphor, a phosphor activated with at least one of rare earth ions and transition metal ions, which emits fluorescence containing a near-infrared light component, can be used. The rare earth ions include Nd 3+ ,EU 2+ , Ho 3+ , Er 3+ , Tm 3+ and Yb 3+ The transition metal ion is preferably at least one selected from the group consisting of Ti 3+ , V 4+ , Cr 4+ , V 3+ , Cr 3+ , V 2+ , Mn 4+ , Fe 3+ , Co 3+ , Co 2+ and Ni 2+ It is preferable that the near-infrared phosphor is at least one selected from the group consisting of: and it is preferable that the near-infrared phosphor is an oxide, sulfide, nitride, halide, oxysulfide, oxynitride, or oxyhalide containing the fluorescent ion.

[0053] In near-infrared phosphors, the preferred fluorescent ion is Cr. 3+ Cr as a fluorescent ion 3+By using this, it becomes easy to obtain a near-infrared phosphor that absorbs visible light, particularly blue light or red light, and converts it into a near-infrared light component. Also, depending on the type of matrix, it becomes easy to change the light absorption peak wavelength and the fluorescence peak wavelength, which is advantageous in changing the excitation spectrum shape and the fluorescence spectrum shape.

[0054] The near-infrared phosphor has many practical achievements, and a phosphor having a garnet-type crystal structure is preferable. Also, the near-infrared phosphor is preferably a phosphor composed of a metal composite oxide activated with Cr 3+ . Specifically, as the near-infrared phosphor, Ln3B’2(AlO4)3:Cr 3+ , Ln3B’2(GaO4)3:Cr 3+ garnet phosphors represented by the general formula are exemplified. Here, Ln is a rare earth element, and B’ is at least one element selected from Al, Ga, and Sc. And it is preferable that Ln is at least one element selected from the group consisting of Y, La, Gd, and Lu. Also, as the near-infrared phosphor, a part of the combination of Ln 3+ -B’ 3+ in the crystal constituting the above garnet phosphor is replaced with a combination of M 2+ -Si 4+ phosphors can also be mentioned. Here, M is an alkaline earth metal, and it is preferably at least one element selected from the group consisting of Ca, Sr, and Ba. Also, as the near-infrared phosphor, a solid solution of the above garnet phosphors may be used.

[0055] The near-infrared phosphor is preferably at least one of a rare earth aluminum garnet phosphor and a rare earth gallium garnet phosphor. Specifically, the near-infrared phosphor is Y3Al2(AlO4)3:Cr 3+ , La3Al2(AlO4)3:Cr 3+ , Gd3Al2(AlO4)3:Cr 3+ , Y3Ga2(AlO4)3:Cr 3+ , La3Ga2(AlO4)3:Cr 3+ , Gd3Ga2(AlO4)3:Cr 3+, Y3Sc2(AlO4)3:Cr 3+ , La3Sc2(AlO4)3:Cr 3+ , Gd3Sc2(AlO4)3:Cr 3+ , Y3Ga2(GaO4)3:Cr 3+ , La3Ga2(GaO4)3:Cr 3+ , Gd3Ga2(GaO4)3:Cr 3+ , Y3Sc2(GaO4)3:Cr 3+ , La3Sc2(GaO4)3:Cr 3+ , Gd3Sc2(GaO4)3:Cr 3+ It is preferably at least one selected from the group consisting of. Further, the near-infrared phosphor may be a solid solution having these phosphors as end components.

[0056] Such Cr 3+ The near-infrared phosphor having as a luminescence center can absorb not only blue light but also red light and convert it into near-infrared light with a wide spectral distribution. Further, such a near-infrared phosphor can convert the absorbed light with a photon conversion efficiency close to the theoretical limit. Therefore, by using such a near-infrared phosphor, not only the primary light 3B emitted from the solid light-emitting element 3 can be reduced, but also near-infrared light having a wide spectral distribution required for inspection can be easily obtained.

[0057] (Photodetector) As long as the photodetector 20 can detect the reflected light 12 of the inspection light 11 reflected by the inspection object 30, various detectors can be used. Specifically, a quantum type photodetector that detects charges generated when light is incident on a PN junction of a semiconductor, such as a photodiode, a phototransistor, a photo IC, a CCD image sensor, a CMOS image sensor, etc. can be used. Also, a thermal type photodetector that detects changes in electrical properties due to a temperature rise caused by the heat generated when light is received, such as a thermopile using the thermoelectric effect and a pyroelectric element using the pyroelectric effect, can also be used. Furthermore, an infrared film sensitive to light can also be used as the photodetector.

[0058] As the photodetector 20, a single element using a photoelectric conversion element alone may be used, or an imaging device in which photoelectric conversion elements are integrated may be used. The form of the imaging device may be linear arranged one-dimensionally or may be planar arranged two-dimensionally.

[0059] A method for inspecting the inspection object 30 by the inspection apparatus 100 having such a configuration will be described. As shown in FIG. 2, the inspection object 30 is placed on the surface 31a of the conveyor 31 and is continuously moving in the direction of the arrow in the figure. And a light source 10 is installed obliquely above the conveyor 31, and a photodetector 20 is installed above the conveyor 31.

[0060] In such an inspection apparatus 100, inspection light 11 is irradiated from the light source 10 toward the inspection object 30. On the surface of the inspection object 30 irradiated with the inspection light 11, red light and near-infrared light are reflected according to the light absorption characteristics and light reflection characteristics of the irradiated object. Then, the reflected light 12 of the inspection light 11 reflected by the inspection object 30 is detected by the photodetector 20.

[0061] Here, as described above, when the inspection object 30 is a food ingredient of a bento and the foreign object is hair, gray hair and white hair in the ingredient can be detected from the image of the red light captured by the photodetector 20, and black hair in the ingredient can be detected from the image of the near-infrared light. For example, in the image, a substance with high light absorption characteristics is displayed in black, and a substance with low light absorption characteristics is displayed in white, so that foreign objects can be detected.

[0062] And as a result of the inspection, when it is determined that the inspection object 30 does not contain foreign objects, the inspection object 30 is moved to the subsequent process. On the other hand, as a result of the inspection, when it is determined that the inspection object 30 contains foreign objects, the inspection object 30 is moved to, for example, a separate line, so that products mixed with foreign objects can be removed.

[0063] In the inspection device 100, the object to be inspected 30 can be food. Note that "food" is a general term for items that people consume, such as ingredients for bento, grains, vegetables, fruits, meat, fish, processed foods, beverages, etc.

[0064] As described above, the inspection device 100 inspects whether a foreign object is contained in the object to be inspected. For example, the inspection device 100 can be used for detecting the presence or state of foreign objects mixed in food. In particular, the inspection device 100 can detect organic substances, especially hair, as foreign objects.

[0065] Here, in food-related factories where work is done by people, not only foreign objects derived from inorganic substances (such as metals and inorganic compounds) that are easy to detect by X-rays, but also foreign objects derived from people, petroleum products, and plants that are difficult to detect by X-rays may be mixed into food. However, by using the inspection device 100, it is possible to detect foreign objects derived from organic substances, so it is possible to reduce the risk of foreign object contamination.

[0066] The inspection device 100 may further include sorting means for sorting the object to be inspected 30 in which a foreign object is detected. Sorting can be carried out by means such as mechanically moving the object to be inspected (abnormal product) in which a foreign object is detected to another line or blowing it away with an air gun. In this way, it is possible to sort the normal products and abnormal products of the object to be inspected, so that the abnormal products can be grouped together. Therefore, it is convenient for the work of grasping the abnormal state and the work for normalization.

[0067] The inspection device 100 may further include visualization means for visualizing the foreign object. Visualization of the foreign object can be carried out by known means using, for example, an image pickup tube or an image pickup element. As a result, the abnormal state of the object to be inspected can be immediately understood by the human eye, so that the operator can correctly understand the abnormal state of the object to be inspected.

[0068] The inspection device 100 preferably also includes an integration means for connecting the visualized foreign object and the inspection object. The integration can be implemented by a display means that displays a composite image obtained by superimposing the image of the foreign object captured by the imaging device and the image of the inspection object. As a result, the defective product itself and the defect information (foreign object information) it has are integrated, so that it is possible to correctly understand the defective state of the product in front of one's eyes and take appropriate measures. The integration can also be implemented by a means for attaching a tag (mark) to the inspection object in which foreign object contamination has been detected. This makes it possible to easily distinguish between normal and defective products even from a distance.

[0069] As described above, the inspection device 100 of the present embodiment includes a light source 10 including a phosphor and a light detector 20. After irradiating the inspection object 30 with the inspection light 11 emitted from the light source 10, the light detector 20 detects the reflected light 12 of the inspection light 11 reflected by the inspection object 30. The spectral distribution of the inspection light 11 has at least two maxima 11A and 11B derived from the fluorescence emitted by the phosphor, and the maxima 11A and 11B are within a wavelength range of 600 nm or more and 750 nm or less. Let the spectral intensity of the maximum value 11A, where the spectral intensity is the maximum at at least one of the maxima 11A and 11B, be Pmax. At this time, the maximum value of the spectral intensity in the wavelength range longer than 750 nm is 20% or more and less than Pmax of Pmax, and the spectral intensity in the wavelength range of 500 nm or more and 550 nm or less is less than 20% of Pmax.

[0070] In addition, the inspection method of this embodiment includes a step of irradiating the inspection object 30 with the inspection light 11, and a step of detecting the reflected light 12 of the inspection light 11 reflected by the inspection object 30. The spectral distribution of the inspection light 11 has at least one maximum value 11A, 11B derived from fluorescence, and the maximum values 11A, 11B are within the wavelength range of 600 nm or more and 750 nm or less. Let the spectral intensity of the maximum value 11A where the spectral intensity is the maximum at at least one maximum value 11A, 11B be Pmax. At this time, the maximum value of the spectral intensity in the wavelength region longer than 750 nm is 20% or more and less than Pmax of Pmax, and the spectral intensity within the wavelength range of 500 nm or more and 550 nm or less is less than 20% of Pmax.

[0071] In the inspection apparatus 100 and the inspection method of this embodiment, since both red and near-infrared light components are used, it is possible to improve the inspection accuracy for similar foreign substances that are difficult to detect only with near-infrared light, such as hairs with different color tones. Furthermore, since the light components are concentrated in the wavelength range for determining the quality of the inspection, it is possible to increase the electro-optical conversion efficiency. In addition, since the inspection object 30 is irradiated with high-intensity red light together with near-infrared light, it is possible to inspect organic foreign substances with a lower reflectance in the red wavelength range than in the near-infrared wavelength range with high accuracy.

[0072] In addition, the phosphor provided in the light source 10 preferably includes a red phosphor that emits red light having a maximum intensity within the wavelength range of 600 nm or more and less than 660 nm, and a near-infrared phosphor that emits near-infrared light having a maximum intensity within the wavelength range of 700 nm or more and less than 1000 nm. Furthermore, it is also preferable that the phosphor consists only of a red phosphor and a near-infrared phosphor. By doing so, the primary light 3B emitted from the solid light-emitting element 3 can be easily wavelength-converted into red and near-infrared light components, which is advantageous for obtaining the red and near-infrared light components required for the inspection light 11.

Example

[0073] Hereinafter, this embodiment will be described in more detail with reference to examples, but this embodiment is not limited to these examples.

[0074] [Fabrication of Light Source] First, a first wavelength conversion type light emitting element composed of a solid light emitting element 3 that emits primary light 3B which is blue light (peak wavelength: 400 to 455 nm) and a first wavelength converter 1A was fabricated.

[0075] As the solid light emitting element 3, a blue LED chip was used. The blue LED chip was manufactured by Osram Opto Semiconductors, product number: LE B P2MQ. Also, the first wavelength converter 1A was a resin phosphor film containing Y3Al2(AlO4)3:Ce 3+ phosphor (YAG phosphor) and (Sr,Ca)AlSiN3:Eu 2+ phosphor (SCASN phosphor). Then, the first wavelength converter 1A and the first wavelength conversion type light emitting element were fabricated as follows.

[0076] First, as phosphor powders, YAG phosphor and SCASN phosphor were prepared. The YAG phosphor was manufactured by Tokyo Chemical Industry Co., Ltd., and the one with a median particle diameter D 50 of about 24 μm was used. This YAG phosphor had a fluorescence peak near a wavelength of 540 nm and emitted yellow - green light. The SCASN phosphor was manufactured by Mitsubishi Chemical Corporation, and the one with a median particle diameter D 50 of about 14 μm was used. This SCASN phosphor had a fluorescence peak near a wavelength of 625 nm and emitted red light. Further, as a sealant for the phosphor powder, a two - component mixed thermosetting silicone resin (manufactured by Shin - Etsu Chemical Co., Ltd., product name: KER - 2500A / B) was prepared.

[0077] Next, YAG phosphor (2.352 g), SCASN phosphor (0.504 g), and silicone resin (0.75 g of agent A and 0.75 g of agent B) were mixed using a stirring and degassing device and further degassed. At this time, the stirring and degassing device was manufactured by Shinki Co., Ltd., product name: Awatori Rentaro (registered trademark), model: ARE - 310. Also, the rotation speed of the stirring and degassing device was set to about 2000 rpm, and the treatment was performed for 3 minutes. In this way, a phosphor paste composed of YAG phosphor, SCASN phosphor, and silicone resin was fabricated.

[0078] The phosphor paste thus obtained was dropped into a frame with a height of about 210 μm provided around a blue LED chip using a dispenser (model: ML-5000XII, manufactured by Musashi Engineering, Inc.). Then, the phosphor paste was heated in the air at 150 °C for 2 hours to cure it. In this way, a resin phosphor film with a thickness of about 200 μm was formed on the main light extraction surface of the blue LED, thereby obtaining the first wavelength converter 1A (5 mm in length, 5 mm in width, and about 200 μm in thickness) and the first wavelength conversion type light emitting element.

[0079] Next, a second wavelength conversion type light emitting element composed of a solid light emitting element 3 and a second wavelength converter 2A was fabricated. The solid light emitting element 3 used a blue LED chip, similar to the first wavelength conversion type light emitting element. The second wavelength converter 2A was a resin phosphor film containing a phosphor mainly composed of a composite metal oxide activated by Cr 3+ and having a fluorescence peak around a wavelength of 750 nm. The phosphor was a (Gd 0.95 La 0.05 )3(Ga 0.97 Cr 0.03 )2(GaO4)3-based (Gd,La)3Ga2(GaO4)3:Cr 3+ phosphor (GLGG phosphor), which has a garnet-type crystal structure.

[0080] The GLGG phosphor was prepared by an orthodox solid-state reaction using the following compound powders as the main raw materials. Gadolinium oxide (Gd2O3): purity 3N, manufactured by Nippon Yttrium Co., Ltd. Lanthanum hydroxide (La(OH)3): purity 3N, manufactured by Shin-Etsu Chemical Co., Ltd. Gallium oxide (Ga2O3): purity 4N, manufactured by Asian Materials Co., Ltd. Chromium oxide (Cr2O3): purity 3N, manufactured by High Purity Chemical Research Institute Co., Ltd.

[0081] Specifically, first, a compound (Gd 0.95 La 0.05 )3(Ga 0.97 Cr 0.03)2(GaO4)3) was produced, and the raw materials were weighed as shown in Table 1 for the weighed values of the raw materials.

[0082]

Table 1

[0083] Next, 20 g of the weighed raw materials were put into an alumina pot mill (capacity 250 ml), together with 200 g of alumina balls (diameter φ3 mm) and 60 ml of ethanol. Then, using a planetary ball mill (manufactured by Fritsch, product number P-5), the pot mill was rotated at a rotational speed of 150 rpm for 30 minutes to wet-mix the raw materials.

[0084] Subsequently, the alumina balls were removed using a sieve to obtain a slurry-like mixed raw material composed of the raw materials and ethanol. Then, the mixed raw material was dried at 125°C using a dryer. And the dried mixed raw material was gently mixed using a mortar and a pestle to obtain a phosphor raw material.

[0085] Next, the phosphor raw material was put into an alumina firing container (material SSA-H, B3 size, with a lid), and fired in the atmosphere at 1500°C for 2 hours using a box-type electric furnace. The heating and cooling rates during firing were set at 300°C / h.

[0086] The obtained fired product was manually crushed using an alumina mortar and pestle, and then passed through a nylon mesh (mesh opening 95 μm) to remove coarse particles, thereby obtaining a powdery GLGG phosphor.

[0087] Although the data was omitted, when the crystal structure of the obtained GLGG phosphor was evaluated using an X-ray diffractometer (desktop X-ray diffractometer, MiniFlex, manufactured by Rigaku Corporation), it was found to be a garnet compound with a nearly single crystal phase. Furthermore, the particle shape and particle size of the GLGG phosphor were evaluated using an electron microscope (desktop microscope Miniscope (registered trademark) TM4000, manufactured by Hitachi High-Technologies Corporation). As a result, the particle shape of the GLGG phosphor was monodisperse particles, and the particle shape could be considered to be derived from the garnet crystal, and the main body of the particle size was around 15 μm.

[0088] Then, the fluorescence characteristics of the GLGG phosphor were evaluated using an absolute PL quantum yield measurement device (C9920-02, manufactured by Hamamatsu Photonics K.K.) under irradiation with blue light having a wavelength of 450 nm. As a result, the fluorescence peak wavelength was 747 nm, the internal quantum efficiency (IQE) was 92%, and the light absorption rate (Abs.) of the blue light was 57%. Also, as a result of evaluation under irradiation with red light having a wavelength of 628 nm, the fluorescence peak wavelength was 746 nm, the internal quantum efficiency (IQE) was 93%, and the light absorption rate (Abs.) of the red light was 45%.

[0089] Using the thus-prepared GLGG phosphor (4.57 g), in the same procedure as the first wavelength converter 1A, a second wavelength converter 2A (5 mm in length, 5 mm in width, thickness: 310 μm) and a second wavelength conversion type light emitting element were prepared.

[0090] Then, using a first wavelength conversion type light emitting element composed of a blue LED and the first wavelength converter 1A and a second wavelength conversion type light emitting element composed of a blue LED and the second wavelength converter 2A, a light source 10 as shown in FIG. 5 was prepared.

[0091] [Evaluation] The light emission characteristics of the obtained light source were evaluated. First, when a current of 500 mA was passed through the blue LED chip of the first wavelength conversion type light emitting element, blue light as primary light 3B was emitted from the blue LED chip. Further, a part of it was converted by the first wavelength conversion body 1A into visible light (orange light by additive mixing of a weak green light component and a strong red light component) as the first wavelength conversion light 1B. Then, the first mixed light composed of the blue light as the primary light 3B and the visible light as the first wavelength conversion light 1B was emitted from the first wavelength conversion type light emitting element. Since the output ratio of the blue light component was sometimes small, the appearance of the mixed light was substantially orange light, and it was light with a color tone that could not be regarded as white light.

[0092] Next, when a current of 500 mA was passed through the blue LED chip of the second wavelength conversion type light emitting element, blue light as primary light 3B was emitted from the blue LED chip. Further, a part of it was converted by the second wavelength conversion body 2A into near-infrared light as the second wavelength conversion light 2B. Then, the second mixed light (purple light) composed of the blue light as the primary light 3B and the near-infrared light as the second wavelength conversion light 2B was emitted from the second wavelength conversion type light emitting element.

[0093] Then, by further mixing the first mixed light and the second mixed light, a mixed light composed of the primary light 3B, the first wavelength conversion light 1B, and the second wavelength conversion light 2B was emitted as output light (inspection light 11). The spectral distribution shown in FIG. 3 is the spectral distribution of the output light emitted from the light source of this example.

[0094] As can be seen from FIG. 3, the spectral distribution of the inspection light 11 has two maxima 11A and 11B derived from the fluorescent components emitted by the phosphor. Among the two maxima 11A and 11B, the maximum 11A with the higher spectral intensity is at a wavelength of 618 nm. When the spectral intensity of the maximum 11A is set to 100%, the maximum value of the spectral intensity in the wavelength range longer than 750 nm is 61% of the spectral intensity at the wavelength where the maximum 11A is located. Note that "61%" is the value at a wavelength of 750 nm. Also, the spectral intensity within the wavelength range of 500 nm or more and 550 nm or less is 16% of the spectral intensity at the wavelength where the maximum 11A is located. Note that "16%" is the value at a wavelength of 550 nm.

[0095] Also, in the spectral intensity within the wavelength range of 550 nm or more and 850 nm or less, the maximum change amount with respect to the wavelength is 4.6% per 1 nm wavelength.

[0096] For reference, FIG. 6(a) shows the spectral distribution of the primary light 3B emitted by the blue LED chip. FIG. 6(b) shows the spectral distribution of the mixed light of the primary light 3B transmitted through the first wavelength converter 1A and the first wavelength-converted light 1B. FIG. 6(c) shows the spectral distribution of the mixed light of the primary light 3B transmitted through the second wavelength converter 2A and the second wavelength-converted light 2B. FIG. 6(d) shows the spectral distribution of the inspection light 11 formed by further mixing the mixed light of FIG. 6(b) and the mixed light of FIG. 6(c).

[0097] As can be seen from FIG. 6(a), the primary light 3B is a single-peak type blue light having a fluorescence peak at a wavelength of 455 nm, and the full width at half maximum is about 22 nm (more than 15 nm and less than 30 nm).

[0098] As can be seen from Fig. 6(b), the mixed light of the primary light 3B that has passed through the first wavelength converter 1A and the first wavelength-converted light 1B contains the light components of the weak-intensity primary light 3B and the first wavelength-converted light 1B. And although the mixed light was red-orange light, the correlated color temperature could not be calculated, the duv, which is an index indicating the deviation from blackbody radiation, could not be calculated, and the average color rendering evaluation number Ra could not be calculated either. Incidentally, the chromaticity of the mixed light in the CIE chromaticity coordinates was (x, y) = (0.594, 0.398). Also, the light component of the first wavelength-converted light 1B had a peak at a wavelength of 618 nm and was a single-peak broad light component having light components over a wide wavelength range of at least 500 nm to 800 nm.

[0099] As can be seen from Fig. 6(c), the mixed light of the primary light 3B that has passed through the second wavelength converter 2A and the second wavelength-converted light 2B contains the light components of the primary light 3B and the second wavelength-converted light 2B. And although the mixed light was substantially blue light, the correlated color temperature could not be calculated, the duv could not be calculated, and the average color rendering evaluation number Ra could not be calculated either. Incidentally, the chromaticity of the mixed light in the CIE chromaticity coordinates was (x, y) = (0.159, 0.043). Also, the light component of the second wavelength-converted light 2B had a peak at a wavelength of 733 nm and was a single-peak broad light component having light components over a wide wavelength range of at least 650 nm to 950 nm.

[0100] As can be seen from Fig. 6(d), the inspection light 11 contained the light components of the primary light 3B, the first wavelength-converted light 1B, and the second wavelength-converted light 2B, and was slightly purple-red light with a white tint. Also, the inspection light 11 had a correlated color temperature of 1736 K, a duv of -49.6, an average color rendering evaluation number Ra of 60, and a chromaticity in the CIE chromaticity coordinates of (x, y) = (0.456, 0.286). Incidentally, the light component of the inspection light 11 had peaks at wavelengths of 453 nm, 618 nm, and 732 nm, and was a multi-peak broad light component having light components over a wide wavelength range of at least 410 nm to 950 nm.

[0101] Note that the inspection light 11 was irradiated onto a white paper placed 20 cm away from the light source, and as a result of visually checking the light irradiated onto the white paper, the irradiated light was homogeneous within at least a range of φ20 cm.

[0102] Next, using this light source 10, an inspection apparatus shown in FIG. 2 was fabricated. First, the photodetector 20 was installed directly above the inspection object 30 and at a position approximately 20 cm away from the inspection object 30. As the photodetector 20, a hyperspectral camera (manufactured by Ximea, model number: MQ022HG-IM-SM4X4-REDNIR) was used. Further, the above-described light source 10 was installed in a direction diagonally upward by approximately 45 degrees from the inspection object 30 and at a position approximately 20 cm away from the inspection object 30. In this way, the inspection apparatus of this example was obtained.

[0103] In this inspection apparatus, after energizing and lighting the light source 10, the emitted inspection light 11 is irradiated onto the inspection object 30, and the state is observed with a hyperspectral camera. Thereby, the state and condition of the inspection object 30 can be inspected.

[0104] Then, the inspection apparatus of this example outputs inspection light including strong visible light with light components concentrated in the wavelength region near 600 nm and deep red to near-infrared light with light components concentrated in the wavelength region near 730 nm. Therefore, it is possible to simultaneously detect a foreign object having a large reflectance difference with respect to the inspection object in the deep red to near-infrared wavelength region and a foreign object of the same type as the foreign object but having a small reflectance difference in the deep red to near-infrared wavelength region. Further, since strong red light is irradiated onto the inspection object, even a foreign object having a relatively small reflectance difference in the red wavelength region with respect to the inspection object can be detected with high sensitivity.

[0105] Furthermore, since the light source of the inspection apparatus of this example converts the input power into light concentrated on the light components minimally necessary for detection, it has excellent electro-optical conversion efficiency. Therefore, the inspection apparatus of this example is also advantageous for low power consumption, resource saving, and miniaturization with high output.

[0106] As described above, although the present embodiment has been described, the present embodiment is not limited to these, and various modifications are possible within the scope of the gist of the present embodiment.

[0107] The entire contents of Japanese Patent Application No. 2021-026793 (filing date: February 22, 2021) are incorporated herein by reference.

Industrial Applicability

[0108] According to the present disclosure, it is possible to provide an inspection apparatus and an inspection method that can detect foreign substances whose light absorption characteristics and light reflection characteristics in the near-infrared region are approximated to those of an object to be inspected, and that are also advantageous for reducing the size and increasing the output of a light source.

Explanation of Reference Numerals

[0109] 3 Solid light-emitting element 10 Light source 11 Inspection light 11A, 11B Maximum value 12 Reflected light 20 Photodetector 30 Object to be inspected 100 Inspection apparatus

Claims

1. A light source comprising a combination of a solid-state light-emitting element and a phosphor, and emitting output light, wherein the solid-state light-emitting element emits primary light having a maximum intensity within a wavelength range of 440 nm or more and less than 480 nm, the phosphor includes a red phosphor that absorbs the primary light and emits red light having a maximum intensity within a wavelength range of 600 nm or more and less than 660 nm, and a near-infrared phosphor that emits near-infrared light having a maximum intensity within a wavelength range of 700 nm or more and less than 1000 nm, the spectral distribution of the output light has one or two maxima within a wavelength range of 600 nm or more and 900 nm or less, both of the maxima are within a wavelength range of 600 nm or more and 750 nm or less, when the spectral intensity of the maximum value having the maximum spectral intensity among the one or two maxima is defined as Pmax, the maximum value of the spectral intensity in the longer wavelength region than 750 nm is 20% or more and less than Pmax of the Pmax, and the spectral intensity within a wavelength range of 500 nm or more and 550 nm or less is less than 20% of the Pmax. A light source.

2. The maximum value derived from the fluorescence emitted by the phosphor takes the maximum intensity of the spectral distribution. The light source according to claim 1.

3. In the spectral intensity within a wavelength range of 550 nm or more and 850 nm or less, the amount of change with respect to the wavelength is less than 5% per 1 nm of wavelength. The light source according to claim 1 or 2.

4. The red phosphor is a phosphor composed of a metal composite nitride or a metal composite oxynitride activated by Eu ２＋ and is a phosphor composed of a metal composite nitride or a metal composite oxynitride activated by Eu The near-infrared phosphor is a phosphor composed of a metal composite oxide activated by Cr ３＋ The light source according to any one of claims 1 to 3, which is a phosphor composed of a metal composite oxide activated by ３＋ .

5. The near-infrared phosphor is a phosphor having a garnet-type crystal structure. The light source according to any one of claims 1 to 4.

6. The solid-state light-emitting element emits 1 W or more of primary light. The light source according to any one of claims 1 to 5.

7. An inspection apparatus comprising the light source according to any one of claims 1 to 6 and a photodetector.

8. The inspection object is food. The inspection apparatus according to claim 7.

9. Inspecting whether the inspection object contains foreign matter. The inspection apparatus according to claim 7 or 8.

10. The foreign matter is hair. The inspection apparatus according to claim 9.

11. An inspection method using the inspection apparatus according to any one of claims 7 to 10, comprising a step of irradiating an inspection object with inspection light, and a step of detecting reflected light of the inspection light reflected by the inspection object. An inspection method having.

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