JP7546205B2 - Light source device and inspection device - Google Patents

Description

The present invention relates to a light source device and an inspection device.

Conventionally, lighting devices that irradiate light toward an object when performing visual inspection of the object are known (see, for example, Patent Document 1).

JP 2017-156132 A

Light source devices for inspection purposes are required not to degrade the quality of the objects being inspected onto which the light is irradiated. They are also required to be highly versatile so that they can be used to inspect as many different types of objects as possible.

The present invention aims to provide a light source device and inspection device that can suppress deterioration of the quality of the object being inspected and is highly versatile.

A light source device according to one aspect of the present invention is a light source device used for inspection, and includes a light source that emits a first light, and an optical member that includes a plurality of wavelength converters that absorb a portion of the first light and emit a second light having a different wavelength from the first light, the optical member having an entrance surface on which the first light is incident, and an exit surface that emits an exit light that includes the second light and another portion of the first light that is incident from the entrance surface, the exit light having an intensity of 5% or more of the peak intensity over a wavelength band of 450 nm or more and less than 800 nm, and the exit surface being an emission surface for the second light.

An inspection device according to one aspect of the present invention includes a light source device according to the above aspect that emits the emitted light toward an object to be inspected, and a light receiving device that receives reflected light of the emitted light from the object to be inspected and outputs an electrical signal according to the intensity of the received reflected light.

The present invention can provide a light source device and inspection device that can suppress deterioration of the quality of the object being inspected and are highly versatile.

FIG. 1 is a perspective view of a light source device according to an embodiment. FIG. 2 is a cross-sectional view of an optical member of the light source device according to the embodiment. FIG. 3 is a diagram showing a spectrum of the emitted light from the light source device according to the embodiment. FIG. 4 is a diagram showing the fluorescence spectra of a plurality of phosphors contained in the optical member of the light source device according to the embodiment. FIG. 5A is a diagram showing an example of the luminance distribution on the emission surface of the optical member of the light source device according to Reference Example 1. FIG. FIG. 5B is a diagram showing another example of the luminance distribution on the exit surface of the optical member of the light source device according to Reference Example 2. FIG. 6 is a diagram showing a configuration of an inspection device including a light source device according to an embodiment, and an object to be inspected. FIG. 7 is a diagram showing an image at a specific wavelength obtained by the inspection device according to the embodiment.

The light source device and the light emitting device according to the embodiments of the present invention will be described in detail below with reference to the drawings. Note that each of the embodiments described below shows a specific example of the present invention. Therefore, the numerical values, shapes, materials, components, arrangement and connection of the components, steps, and order of steps shown in the following embodiments are merely examples and are not intended to limit the present invention. Therefore, among the components in the following embodiments, components that are not described in the independent claims will be described as optional components.

In addition, each figure is a schematic diagram and is not necessarily an exact illustration. Therefore, for example, the scales of each figure do not necessarily match. In addition, in each figure, substantially the same configuration is given the same reference numerals, and duplicate explanations are omitted or simplified.

In addition, in this specification, terms indicating the relationship between elements, such as vertical, terms indicating the shape of elements, such as circular or rectangular, and numerical ranges are not expressions that express only a strict meaning, but are expressions that include a substantially equivalent range, for example, a difference of about a few percent.

In addition, in this specification, the "peak wavelength" refers to the wavelength at which the emission intensity is maximum within a specified wavelength band. The intensity at the peak wavelength is referred to as the "peak intensity." The peak intensity does not have to be the maximum intensity in the entire wavelength band. In other words, a peak with an intensity higher than the peak intensity within a specified wavelength band may exist in a band other than the specified wavelength band.

In addition, in this specification, ordinal numbers such as "first" and "second" do not refer to the number or order of components, unless otherwise specified, but are used for the purpose of avoiding confusion and distinguishing between components of the same type.

(Embodiment)
[composition]
First, the configuration of a light source device according to the embodiment will be described with reference to FIG.

Figure 1 is a perspective view of a light source device 1 according to the present embodiment. The light source device 1 is a light source device used for inspection. The inspection may be, for example, an inspection of an object to be inspected for defects in appearance, or an inspection of a foreign object mixed in the object to be inspected. The object to be inspected may be food, medicine, industrial product, etc.

As shown in FIG. 1, the light source device 1 includes a base 10, a light source 20, and an optical member 30.

The base 10 is a member that supports the light source 20. The base 10 is, for example, a flat plate-like member formed using a material with high heat dissipation properties, such as metal, but the shape and material of the base 10 are not particularly limited.

The light source 20 emits a first light L1 (see FIG. 2). The light source 20 is an LED (Light Emitting Diode) element. In the present embodiment, the first light L1 is blue light having a peak wavelength in a wavelength band of 430 nm or more and 495 nm or less. For example, the light source 20 is a blue LED element having a peak wavelength of 459 nm. The energy of the first light L1 is 1 W or more, but is not limited thereto. The energy of the first light L1 may be 10 W or more, or may be 20 W or more. The energy of the first light L1 may be 0.2 W or more, or may be 0.5 W or more. As an example, the energy of the first light L1 is 24.7 W, and the irradiance is 6.25 W/cm ² .

The optical member 30 is a member that includes multiple wavelength converters. The multiple wavelength converters absorb a portion of the first light L1 and emit a second light L2 (see FIG. 2) that has a different wavelength from the first light L1. The multiple wavelength converters are, for example, particulate matter. The optical member 30 is an aggregate (for example, a ceramic sintered body) in which the multiple wavelength converters are aggregated.

Alternatively, the optical member 30 may have a plate-shaped resin substrate (not shown) in which a plurality of wavelength converters are mixed and dispersed. The optical member 30 may also have a transparent plate material in which a plurality of wavelength converters are mixed and dispersed in a transparent resin applied to the surface of the plate material.

Figure 2 is a cross-sectional view of the optical member 30 of the light source device 1 according to this embodiment. As shown in Figure 2, the optical member 30 has an incident surface 30a on which the first light L1 is incident, and an exit surface 30b from which the exit light L is emitted. The exit surface 30b is an emission surface for the second light L2. In this embodiment, the intensity distribution (specifically, the luminance distribution) of the exit light L on the exit surface 30b is constant or changes smoothly along an arbitrary direction. Note that "changing smoothly" means that the change in luminance is continuous, and that the rate of change in luminance along one direction is constant or within a predetermined range.

The optical member 30 is a plate material in which the entrance surface 30a and the exit surface 30b face each other. As shown in FIG. 1, the optical member 30 is a flat plate with the exit surface 30b having a circular shape, but is not limited to this. The shape of the exit surface 30b may be a square or rectangle, or may be a polygon such as a hexagon or octagon.

The thickness T of the optical member 30 is, for example, 1 mm or less. The maximum length W of the exit surface 30b of the optical member 30 is, for example, 5 mm or more and 30 mm or less. The maximum length W is the diameter of the circular exit surface 30b. In this embodiment, the ratio (W/T) of the maximum length W of the exit surface 30b to the thickness T of the optical member 30 is 20 or more. W/T may be 10 or more. W/T may be 100 or more.

The emitted light L includes a part of the first light L1 and the second light L2. The energy of the emitted light L is 1 W or more, but is not limited to this. The energy of the emitted light L may be 10 W or more, or may be 20 W or more. As an example, the energy of the emitted light L is 11.4 W, and the irradiance is 2.75 W/ ^cm2 .

Figure 3 is a diagram showing the spectrum of the emitted light L of the light source device 1 according to this embodiment. Figure 4 is a diagram showing the fluorescence spectrum of multiple phosphors contained in the optical member 30 of the light source device 1 according to this embodiment. In Figures 3 and 4, the horizontal axis represents the wavelength, and the vertical axis represents the relative value of the emission intensity.

As shown in FIG. 3, the emitted light L has an intensity equal to or greater than a predetermined percentage of the peak intensity over the wavelength band of 450 nm or more and less than 800 nm. The predetermined percentage is, for example, 5%, but may be 3%, 10%, or 20%. In other words, the emitted light L is broad light that has an intensity equal to or greater than a certain level over the entire wavelength band of 450 nm or more and less than 800 nm. The emitted light L has an intensity less than a predetermined percentage of the peak intensity in the wavelength band of 430 nm or less and the wavelength band of 900 nm or more. The predetermined percentage here is, for example, 5%, but may be 3%, 10%, or 20%.

The emitted light L has peaks at approximately 460 nm, approximately 540 nm, and approximately 730 nm. The first peak at approximately 460 nm is a peak based on the first light L1 emitted from the light source 20. The second peak at approximately 540 nm and the third peak at approximately 730 nm are each peaks based on the second light L2 emitted by the multiple wavelength converters.

In this embodiment, as shown in FIG. 2, the multiple wavelength converters include three or more types of phosphors having different emission wavelengths. As shown in FIG. 2, the multiple wavelength converters include phosphors 31 to 33. The first light L1 functions as excitation light for each of the phosphors 31 to 33.

The phosphor 31 absorbs a part of the first light L1 and emits a second light L21 having a wavelength different from that of the first light L1. The peak wavelength of the second light L21 is longer than that of the first light L1. Specifically, as shown in FIG. 4, the second light L21 is green light having a peak wavelength in a wavelength band of 505 nm or more and less than 525 nm. The second light L21 has an intensity equal to or greater than a predetermined ratio of the peak intensity over a wavelength band of 500 nm or more and 600 nm or less. The predetermined ratio is, for example, 5%, but may be 3%, 10%, or 20%. That is, the second light L21 is a light having a larger half-width and a broader spectrum than the first light L1. For example, the phosphor 31 is a Lu ₃ Al ₅ O ₁₂ :Ce ³⁺ phosphor (LuAG:Ce ³⁺ ) having an excitation wavelength of 455 nm and a peak wavelength of 512 nm. The phosphor 31 may be any phosphor having a fluorescence spectrum equivalent to that of LuAG:Ce ^{3+ , and other green phosphors may be used instead of or in addition to LuAG:Ce 3+. Examples of other green phosphors that can be used include Ca 3 Sc 2 Si 3 O 12 :Ce 3+ and} _{Ca ( Sc ,} ^Lu ) ₂ O ₄ :Ce ³⁺ .

The second light L21 may be red light having a peak wavelength in a wavelength band of 600 nm or more and less than 660 nm. When the second light L21 is red light, the second light L21 has an intensity equal to or greater than a predetermined ratio of the peak intensity over a wavelength band of 580 nm or more and 700 nm or less. The predetermined ratio is, for example, 5%, but may be 3%, 10%, or 20%. That is, the second light L21 is a light having a larger half-width and a broader intensity than the first light L1. When the second light L21 is red light, for example, the phosphor 31 is a (Sr, Ca)AlSiN ₃ :Eu ²⁺ phosphor (SCASN:Eu ²⁺ ) having an excitation wavelength of 455 nm and a peak wavelength of 625 nm. Phosphor 31 may be any phosphor having a fluorescence spectrum equivalent to that of SCASN:Eu ²⁺ , and other red phosphors may be used instead of or in addition to SCASN:Eu ^{2+ .}

The phosphor 32 absorbs another part of the first light L1 and emits a second light L22 having a wavelength different from that of the first light L1. The peak wavelength of the second light L22 is longer than the peak wavelengths of the first light L1 and the second light L21. Specifically, as shown in FIG. 4, the second light L22 is a yellow light having a peak wavelength in a wavelength band of 525 nm to 600 nm. The second light L22 has an intensity equal to or greater than a predetermined ratio of the peak intensity over a wavelength band of 500 nm to 600 nm. The predetermined ratio is, for example, 5%, but may be 3%, 10%, or 20%. In other words, the second light L22 is a light having a larger half-width and a broader intensity than the first light L1. For example, the phosphor 32 is _{a Y3Al5O12} :Ce3 ⁺ phosphor (YAG:Ce3 ⁺ ) having an excitation wavelength of 455 nm and a peak wavelength of 545 _nm . Note that the phosphor 32 may be any phosphor having a fluorescence spectrum equivalent to that of YAG: ^{Ce3 +} , and other yellow phosphors may be used instead of or in addition to YAG:Ce3 ⁺ .

The phosphor 33 absorbs another part of the first light L1 and emits a second light L23 having a wavelength different from that of the first light L1. The peak wavelength of the second light L23 is longer than the peak wavelengths of the first light L1, the second light L21, and the second light L22. Specifically, as shown in FIG. 4, the second light L23 is near-infrared light having a peak wavelength in a wavelength band of 700 nm or more. The second light L23 has an intensity equal to or greater than a predetermined ratio of the peak intensity over a wavelength band of 700 nm or more and 800 nm or less. The predetermined ratio is, for example, 5%, but may be 3%, 10%, or 20%. In other words, the second light L23 is a light having a larger half-width and a broader intensity than the first light L1. For example, the phosphor 33 is _{a ( Gd0.8La0.2 ) 3} ( _{Ga0.47Sc0.50Cr0.03} ) _2Ga5O12 phosphor (GGG) having an excitation wavelength of 455 nm and a peak wavelength of ₇₆₅ nm. Note that the phosphor 33 may be any phosphor having a fluorescence spectrum equivalent to that of GGG, _and other near-infrared phosphors may be used instead of or in addition to GGG.

The optical member 30 may contain only one type of phosphor, two types, or four or more types. The mixing ratio of each phosphor is not particularly limited, as long as the emitted light L is broad light in the wavelength band of 450 nm or more and less than 800 nm. The optical member 30 may contain one or more types of visible light phosphors and may not contain a near-infrared phosphor.

[Example]
Next, a specific example of the optical member 30 of the light source device 1 described above will be described.

For the optical member 30 used in the examples, a phosphor having a fluorescence peak in the wavelength band of near-infrared light (near-infrared phosphor) was used as an example of phosphor 33, and a phosphor having a fluorescence peak in the wavelength band of visible light (visible light phosphor) was used as an example of phosphors 31 and 32. The near-infrared phosphor was made in-house, and the visible light phosphor was obtained from an external source. The chemical composition of the visible light phosphor and the source of its acquisition are as shown below.

_Lu3Al5O12 : _{Ce3 +} , Nemoto Specialty Chemicals Co., Ltd. _CaAlSiN3 ^: Eu2 ⁺ , Mitsubishi Chemical Corporation

First, the near-infrared phosphor used in _the examples was synthesized by a preparation method using a solid-state reaction. The near-infrared phosphor used in the examples is an oxide phosphor represented by the composition formula ( _Gd0.95La0.05 ) ₃ ( _Ga0.97Cr0.03 ) _2Ga3O12 . The near-infrared phosphor used in the examples is a _Cr3 ⁺ activated phosphor. The near-infrared phosphor used in the examples uses the following compound _powder as a _raw material.

Gadolinium oxide (Gd ₂ O ₃ ): Purity 3N, Wako Pure Chemical Industries, Ltd. Lanthanum oxide (La ₂ O ₃ ): Purity 3N, Wako Pure Chemical Industries, Ltd. Gallium oxide (Ga ₂ O ₃ ): Purity 4N, Wako Pure Chemical Industries, Ltd. Chromium oxide (Cr ₂ O ₃ ): Purity 3N, Kojundo Chemical Laboratory Co., Ltd.

The raw materials were weighed out to obtain a compound with a stoichiometric composition ( _Gd0.95La0.05 ) ₃ ( _Ga0.97Cr0.03 ) _{2Ga3O12 .} The weighed _raw materials were then mixed by hand using _a mortar and _pestle . In this manner, a mixed raw material was obtained.

The mixed raw materials were placed in an alumina crucible and sintered in an electric furnace. The sintering temperature was 1600°C. The sintering atmosphere was air.

The fired product was lightly crushed by hand using a mortar and pestle. In this way, the near-infrared phosphor used in the examples was obtained. Note that the near-infrared phosphor used in the examples is a particulate phosphor.

The near-infrared phosphor obtained by the above procedure was dispersed in silicone resin. The volume ratio of the near-infrared phosphor to the silicone resin was 30%. Then, the paste in which the near-infrared phosphor was dispersed in the silicone resin was applied onto a blue LED element, which is an example of a light source 20, using a dispenser. Then, a heat treatment was performed at a temperature of 150°C using a dryer to harden the paste. In this way, an LED element coated with the near-infrared phosphor was obtained.

Next, the visible light phosphor used in the embodiment was dispersed in silicone resin. Specifically, Lu ₃ Al ₅ O ₁₂ : Ce ³⁺ phosphor and CaAlSiN ₃ : Eu ²⁺ phosphor were dispersed in silicone resin. The volume ratios of Lu ₃ Al ₅ O ₁₂ : Ce ³⁺ phosphor and CaAlSiN ₃ : Eu ²⁺ phosphor to silicone resin were 4% and 6%, respectively. Then, the paste in which the visible light phosphor was dispersed in the silicone resin was applied on the near-infrared phosphor applied on the LED element using a dispenser. Then, the paste was heat-treated at a temperature of 150°C using a dryer to harden the paste. In this way, a light source device 1 consisting of a blue LED element, a near-infrared phosphor layer, and a visible light phosphor layer was obtained.

The thicknesses of the near-infrared phosphor layer and the visible light phosphor layer were 240 μm and 60 μm, respectively. In other words, the thickness T of the optical member 30 consisting of the near-infrared phosphor layer and the visible light phosphor layer was 300 μm.

The optical member 30, which is made up of a near-infrared phosphor layer and a visible light phosphor layer, has an exit surface 30b for the emitted light L that is perpendicular to the thickness direction, and the shape of the exit surface 30b in a plan view is rectangular. The maximum length W of the exit surface 30b was 7000 μm. In other words, the ratio (W/T) of the maximum length W of the exit surface 30b to the thickness T of the optical member 30 was approximately 23.

Next, the spectrum of the output light L emitted by the light source device 1 was evaluated using an integrating sphere and a multichannel spectrophotometer. Figure 3 shows the spectrum of the output light emitted by the light source device 1 according to the embodiment. As shown in Figure 3, the output light L emitted by the light source device 1 according to the embodiment had a ratio of the minimum fluorescence intensity to the maximum fluorescence intensity of 0.05 or more in the wavelength band of 450 nm or more and less than 800 nm. In other words, the output light L emitted by the light source device 1 according to the embodiment had light components over the entire wavelength band of 450 nm or more and less than 800 nm.

The intensity distribution of the emitted light L on the emission surface 30b of the light source device 1 according to the embodiment will be described with reference to Figures 5A and 5B. Figures 5A and 5B are diagrams showing the luminance distribution on the emission surface of the light source devices according to Reference Examples 1 and 2, respectively. In Figures 5A and 5B, the darkness of the shading corresponds to the luminance, with the darker the area, the higher the luminance.

The light source device according to Reference Example 1 is a light source device made by the same procedure as in the Examples, and is composed of a blue LED element and a near-infrared phosphor layer. In other words, the light source device according to Reference Example 1 has a configuration in which the visible light phosphor layer is removed from the light source device 1 according to the Examples. The light source device according to Reference Example 2 is a light source device made of a blue LED element and a visible light phosphor layer. In other words, the light source device according to Reference Example 2 has a configuration in which the near-infrared phosphor layer is removed from the light source device 1 according to the Examples.

As shown in Fig. 5A, the luminance of the emitted light on the emission surface of the light source device according to Reference Example 1 was 14.95 cd/ ^cm2 or more in all regions. That is, the emission surface of the light source device according to Reference Example 1 had light intensity in all regions, and the intensity distribution (luminance distribution) of the emitted light on the emission surface of the light source device according to Reference Example 1 was continuous. That is, the intensity distribution on the emission surface of the light source device according to Reference Example 1 changed constantly or smoothly along any direction.

As shown in Fig. 5B, the luminance of the emitted light on the emission surface of the light source device according to Reference Example 2 was 306.4 cd/ ^cm2 or more in all regions. That is, the emission surface of the light source device according to Reference Example 2 had light intensity in all regions, and the intensity distribution (luminance distribution) of the emitted light on the emission surface of the light source device according to Reference Example 2 was continuous. That is, the intensity distribution on the emission surface of the light source device according to Reference Example 2 changed constantly or smoothly along any direction.

From the above results, it is self-evident that the intensity distribution of the emitted light on the exit surface 30b is continuous, even when the light source device 1 according to the embodiment is made up of a blue LED element, a near-infrared phosphor layer, and a visible light phosphor layer. In other words, the intensity distribution on the exit surface 30b of the light source device 1 is constant or changes smoothly along any direction.

[Inspection equipment]
Next, an inspection using the light source device 1 according to the present embodiment will be described.

Figure 6 is a diagram showing the configuration of an inspection device 100 equipped with a light source device 1 according to this embodiment, and an inspection object 101. The inspection object 101 is, for example, black paper, but it may also be food such as seaweed or hijiki. A foreign object 102 is mixed into the inspection object 101. The foreign object 102 is, for example, a hair. It is difficult to find the foreign object 102 with the naked eye. The inspection device 100 according to this embodiment inspects the presence or absence of the foreign object 102 in the inspection object 101.

As shown in FIG. 6, the inspection device 100 includes a light source device 1, a light receiving device 110, and a signal processing circuit 120.

The light source device 1 emits light L toward the object to be inspected 101.

The light receiving device 110 receives reflected light Lr of the emitted light L from the inspection target 101 and outputs an electrical signal according to the intensity of the received reflected light Lr. The light receiving device 110 is, for example, a hyperspectral camera. The light receiving device 110 can obtain the spectrum of the reflected light Lr for each pixel.

The signal processing circuit 120 detects the foreign matter 102 on the inspection target 101 by processing the electrical signal output from the light receiving device 110. For example, the signal processing circuit 120 can obtain an image of a specific wavelength shown in FIG. 7 by extracting the intensity of a specific wavelength component for each pixel.

Figure 7 is a diagram showing an image 121 at a specific wavelength obtained by the inspection device 100 according to this embodiment. In the image 121, the foreign object 102 is emphasized. This is based on the difference in the light reflection characteristics between the foreign object 102 and the object to be inspected 101. For example, at a specific wavelength, the reflectance of the foreign object 102 is higher than the reflectance of the object to be inspected 101. Therefore, in the image 121 at the specific wavelength, the foreign object 102 and the object to be inspected 101 are displayed in different colors. This makes it possible to detect the foreign object 102.

The light receiving device 110 does not have to be a hyperspectral camera, and may include, for example, a filter that passes specific wavelength components and an image sensor that receives the light that passes through the filter. The light receiving device 110 may include multiple filters with different pass bands. The multiple filters may be switchable depending on the reflection characteristics of the inspection target object 101 or the foreign object 102.

[Effects, etc.]
As described above, the light source device 1 according to the present embodiment is a light source device used for inspection, and includes a light source 20 that emits a first light L1, and an optical member 30 that includes a plurality of wavelength converters that absorb a portion of the first light L1 and emit a second light L2 having a wavelength different from that of the first light L1. The optical member 30 has an incident surface 30a on which the first light L1 is incident, and an exit surface 30b that emits an exit light including another portion of the first light L1 incident from the incident surface 30a and the second light L2. The exit light L has an intensity of 5% or more of the peak intensity over a wavelength band of 450 nm or more and less than 800 nm. The exit surface 30b is an emission surface of the second light L2.

As a result, by utilizing the broad emitted light L, it becomes possible to extract reflected light of a specific wavelength. This makes it possible to inspect not only specific inspection objects and/or specific foreign bodies, but also various inspection objects for various foreign bodies. In other words, a highly versatile light source device 1 can be realized.

For example, halogen lamps and the like are known as light sources that emit broad light. However, when a halogen lamp is used, the heat generated by the halogen lamp reduces the quality of the object to be inspected. In contrast, the light source device 1 according to the present embodiment uses the first light L1 from the light source 20 and the second light L2 from the wavelength converter included in the optical member 30 as the emitted light L, thereby making it possible to suppress deterioration in the quality of the object to be inspected.

In this way, deterioration of the quality of the object being inspected can be suppressed, and a highly versatile light source device 1 can be realized.

Furthermore, for example, the intensity distribution of the emitted light L at the exit surface 30b is constant or changes smoothly along any direction.

This makes it possible to suppress unevenness in the intensity of the emitted light L, and therefore to suppress unevenness in the image generated by receiving the light reflected by the object being inspected. This makes it possible to support highly accurate inspections.

For example, the optical member 30 is a plate material in which the incident surface 30a and the exit surface 30b face each other. The ratio of the maximum length W of the exit surface 30b to the thickness T of the optical member 30 is 20 or more.

This makes it possible to realize a low-profile light source device 1 that emits light L over a wide range.

Also, for example, the energy of the emitted light L is 1 W or more.

This allows the object to be irradiated with emitted light L of sufficient intensity for inspection. In addition, since the light source device 1 can be spaced apart from the object to be inspected, it is possible to prevent the heat generated by the light source device 1 from being transmitted to the object to be inspected. This makes it possible to prevent deterioration in the quality of the object to be inspected.

For example, the multiple wavelength converters include phosphors having a peak wavelength in a wavelength band of 700 nm or more.

This allows the emitted light L to contain strong near-infrared light. This makes it possible to perform inspections that are difficult to perform with the naked eye. Furthermore, the phosphor can be used semi-permanently, which extends the life of the light source device 1. This reduces the frequency of maintenance of the light source device 1.

For example, the multiple wavelength converters may include three or more types of phosphors that have different emission wavelengths.

This allows the spectrum of the emitted light L to be appropriately adjusted depending on the type and amount of phosphor. Therefore, the light source device 1 can emit emitted light L having an appropriate spectrum depending on the type of object to be inspected.

In addition, for example, by using an LED element as the light source 20, the cost of the light source device 1 can be reduced compared to when a laser element is used.

The inspection device 100 according to this embodiment also includes a light source device 1 that emits emitted light L toward an object to be inspected, and a light receiving device 110 that receives reflected light Lr of the emitted light L from the object to be inspected and outputs an electrical signal according to the intensity of the received reflected light Lr.

As a result, the inspection device 100 can inspect various foreign objects in various types of inspection objects by selecting an appropriate wavelength depending on the combination of the inspection object and foreign object, since the light source device 1 emits broad emission light L. This makes it possible to realize a highly versatile inspection device 100.

(others)
Although the light source device and the inspection device according to the present invention have been described based on the above-mentioned embodiment, the present invention is not limited to the above-mentioned embodiment.

For example, the intensity distribution of the emitted light at the exit surface does not have to be continuous. The intensity distribution of the emitted light at the exit surface may vary discretely along one direction.

For example, the shape of the optical member does not have to be a flat plate, but may be a curved plate. The optical member may be rod-shaped or block-shaped. For example, the optical member may be provided in direct contact with the light-emitting surface of the light source, or may be disposed at a distance from the light source.

In addition, the present invention also includes forms obtained by applying various modifications to each embodiment that a person skilled in the art may conceive, and forms realized by arbitrarily combining the components and functions of each embodiment within the scope of the spirit of the present invention.

Reference Signs List 1 Light source device 20 Light source 30 Optical member 30b Emission surface 31, 32, 33 Phosphor 100 Inspection device 101 Inspection target 102 Foreign matter 110 Light receiving device 120 Signal processing circuit L Emitted light L1 First light L2, L21, L22, L23 Second light Lr Reflected light

Claims (7)

A light source device used for inspection,
a light source that emits a first light having a peak wavelength in a wavelength band of 430 nm or more and 495 nm or less ;
an optical member including a plurality of types of wavelength converters each having a different emission wavelength ;
The plurality of types of wavelength converters are
a near-infrared phosphor that absorbs a portion of the first light and emits near-infrared light having a wavelength different from that of the first light;
a visible light phosphor that absorbs a portion of the first light and emits visible light having a wavelength different from that of the first light,
The near infrared phosphor is a Cr3+ activated phosphor ^,
The optical member is
an incidence surface on which the first light is incident;
an exit surface that emits exit light including another portion of the first light incident from the entrance surface , the near-infrared light, and the visible light;
a near-infrared phosphor layer containing only the near-infrared phosphor;
a visible light phosphor layer containing the visible light phosphor;
the emitted light has an intensity of 5% or more of a peak intensity over a wavelength band of 450 nm or more and less than 800 nm;
the near-infrared phosphor layer and the visible light phosphor layer are disposed in this order from the light source side,
The exit surface is an emitting surface of the visible light.
Light source device. The intensity distribution of the emitted light on the emission surface is constant or changes smoothly along an arbitrary direction.
The light source device according to claim 1 . the optical member is a plate material in which the incident surface and the exit surface are back-to-back with each other,
The ratio of the maximum length of the exit surface to the thickness of the optical member is 20 or more.
3. A light source device according to claim 1 or 2. The energy of the emitted light is 1 W or more.
The light source device according to any one of claims 1 to 3. The near-infrared phosphor has a peak wavelength in a wavelength band of 700 nm or more.
The light source device according to any one of claims 1 to 4. The plurality of types of wavelength converters include three or more types of phosphors having different emission wavelengths.
The light source device according to any one of claims 1 to 5. The light source device according to any one of claims 1 to 6, which emits the emitted light toward an object to be inspected;
a light receiving device that receives reflected light of the emitted light from the inspection object and outputs an electrical signal according to the intensity of the received reflected light.
Inspection equipment.

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