Light-emitting device

Abstract

The present invention provides a light-emitting device capable of emitting light with a discontinuous spectral distribution. [Solution] The device comprises an excitation light source that emits excitation light having a peak wavelength of 340 nm or more and 410 nm or less, and a phosphor having at least one type of fluorescent substance, which is arranged in the direction of propagation of the excitation light emitted from the excitation light source, wherein the phosphor is excited by the excitation light and the light emitted from the phosphor has a predetermined spectral distribution in the range of 320 nm or more and 700 nm or less, and the predetermined spectral distribution includes at least one discontinuous spectral region.

Description

Technical Field

[0001] The present invention relates to a light-emitting device that emits light for illuminating an object.

Background Art

[0002] Currently, when inspecting unevenness in the thickness of a film or the like, a three-wavelength fluorescent lamp is used. The spectral distribution of the three-wavelength fluorescent lamp has peaks in blue, green, and red. Further, the three-wavelength fluorescent lamp has a spectral distribution in which a part between blue and green and a part between green and red are discontinuous.

[0003] Despite having such usefulness, in recent years, the production and sales of fluorescent lamps have been shrinking, and fluorescent lamp manufacturers plan to discontinue production in a few years. In such a situation, there has been a movement to replace fluorescent lamps with LED lighting. However, general, for example, white LED lighting uses a 450 nm blue LED as an excitation source and uses a phosphor of yellow or green and red to create white. Its spectral distribution becomes a continuous spectrum from around 400 nm, which is slightly shorter wavelength than the 450 nm excitation source, to about 780 nm. For achieving high reproducibility of all colors for general illumination, LED lighting having such a continuous spectrum is more advantageous. <​​​​​​​​​​​​​​​​​​​ [Problems that the invention aims to solve]

[0006] Three-wavelength fluorescent lamps have been used to inspect for inconsistencies in film thickness because a discontinuity in the spectrum is necessary. By using a discontinuous spectrum, inconsistencies in film thickness appear as interference fringes, making inspection possible. However, when using solid-state light sources such as LEDs, it is difficult to obtain a discontinuous spectrum.

[0007] The present invention has been made in view of the above-mentioned points. Its objective is to provide a light-emitting device that can emit light having a discontinuous spectral distribution even when a solid-state light source is used. [Means for solving the problem]

[0008] The features of the light-emitting device according to the present invention are: An excitation light source that emits excitation light with a peak wavelength of 340 nm or higher and 410 nm or lower, A blue light source that emits blue light with a peak wavelength of 410 nm or higher and 450 nm or lower, A phosphor comprising at least one type of fluorescent substance, wherein the phosphor is arranged in the direction of propagation of the excitation light emitted from the excitation light source, The phosphor is excited by the excitation light, and the light emitted from the phosphor has a predetermined spectral distribution in the range of 320 nm or more and 700 nm or less. The blue light emitted from the blue light source passes through the phosphor without being converted by the phosphor and is emitted from the light-emitting device. The predetermined spectral distribution is A first discontinuous region is formed in the range of approximately 405 nm or more and 430 nm or less, A second discontinuous region is formed in the range of approximately 470 nm or more and 540 nm or less, A third discontinuous region is formed in the range of approximately 560 nm or more and 610 nm or less, Includes, Let M0 be the intensity at the peak of the excitation light. The maximum intensity M1 in the first discontinuity region, the maximum intensity M2 in the second discontinuity region, and the maximum intensity M3 in the third discontinuity region are all less than or equal to one-tenth of M0. That is the case. [Effects of the Invention]

[0009] We can provide a light-emitting device that can emit light with a discontinuous spectral distribution. [Brief explanation of the drawing]

[0010] [Figure 1] It is a cross-sectional view showing the structure of the light-emitting device 10 according to the first embodiment. [Figure 2] It is a perspective view showing the structure of the light-emitting device 10 according to the first embodiment. [Figure 3] It is a cross-sectional view showing the structure of the light-emitting device 20 according to the second embodiment. [Figure 4] It is a perspective view showing the structure of the light-emitting device 20 according to the second embodiment. [Figure 5] It is a cross-sectional view showing the structure of the light-emitting device 30 according to the third embodiment. [Figure 6] It is a perspective view showing the arrangement of the phosphor 360 of the light-emitting device 30 according to the third embodiment. [Figure 7] It is a graph showing the spectrum of the light emitted from the light-emitting device 10. [Figure 8] It is a graph showing the spectrum of the light emitted from the light-emitting device 10.

Embodiments for Carrying Out the Invention

[0011] <<<<Summary of the Present Embodiment>>>> <<First Feature>> According to the first feature, an excitation light source that emits excitation light having a peak wavelength of 340 nm or more and 410 nm or less, a phosphor having at least one kind of fluorescent substance, the phosphor being arranged in the traveling direction of the excitation light emitted from the excitation light source, and the phosphor is excited by the excitation light, and the light emitted from the phosphor has a predetermined spectral distribution in the range of 320 nm or more and 700 nm or less, the predetermined spectral distribution includes at least one discontinuous spectral region, and a light-emitting device is provided.

[0012] The light-emitting device according to the first feature comprises an excitation light source and a phosphor. The excitation light source emits excitation light with a peak wavelength of 340 nm or more and 410 nm or less. The phosphor has at least one type of fluorescent substance. Furthermore, the phosphor is positioned in the direction of propagation of the excitation light emitted from the excitation light source. The excitation light emitted from the excitation light source is incident on the phosphor.

[0013] When a phosphor (fluorescent substance) is excited by excitation light emitted from an excitation light source, fluorescence is emitted from the phosphor. The fluorescence emitted from the phosphor (fluorescent substance) has a predetermined spectral distribution in the range of 320 nm or more and 700 nm or less. The fluorescence emitted as fluorescence from the phosphor (fluorescent substance) is light with wavelengths of so-called visible light.

[0014] <Discontinuity> This predetermined spectral distribution includes at least one discontinuous spectral region. A discontinuity means that the predetermined spectral distribution has a region where the intensity is lower than the predetermined intensity. Specifically, a discontinuity means that there is a region where the intensity is preferably 10% or less of the maximum intensity included in the predetermined spectral distribution. This 10% standard is a guideline for creating an intensity difference that can be clearly distinguished from other wavelength components in the spectral distribution, and is a range that is empirically effective in improving the visibility of interference fringes.

[0015] Furthermore, preferably, there is a region where the intensity is 20% or less. Moreover, there should be a region where the intensity is at least 30% or less. There should be discontinuous regions in the spectral distribution so that interference fringes are formed for inspection of the illuminated object. Interference fringes are striped patterns formed by the interference of different waves and are visible when light overlaps under specific conditions.

[0016] The definition of discontinuity is based on the maximum intensity included in a given spectral distribution, but is not limited to this. For example, it may also be defined as a region where the intensity of the area between two adjacent intensity peaks in a given spectral distribution is 10% or less of the intensity of either of the two peaks. Alternatively, the average intensity of two adjacent intensity peaks in a given spectral distribution may be used as the reference. Furthermore, if there are three or more intensity peaks in a given spectral distribution, the average intensity of these peaks may be used as the reference.

[0017] <<Second characteristic>> The second characteristic is, in the first characteristic, There are two types of fluorescent substances.

[0018] <<Third characteristic>> The third characteristic is, in the first characteristic, There are three types of fluorescent substances.

[0019] <<Fourth characteristic>> The fourth characteristic is, in the first characteristic, The excitation light has a peak wavelength that falls within the range of 340 nm or more and 410 nm or less.

[0020] <<The fifth characteristic>> The fifth characteristic is, in the first characteristic, The predetermined spectral distribution includes one discontinuous spectral region.

[0021] A given spectral distribution has two peaks because it includes one discontinuous spectral region.

[0022] <<Feature #6>> The sixth feature is, in the first feature, The aforementioned predetermined spectral distribution includes two discontinuous spectral regions.

[0023] A given spectral distribution has three peaks because it includes two discontinuous spectral regions.

[0024] <<Characteristic 7>> The seventh feature is, in the first feature, The aforementioned predetermined spectral distribution includes three discontinuous spectral regions.

[0025] By including three discontinuous spectral regions, a given spectral distribution has four peaks.

[0026] <<Feature #8>> The eighth feature is, in the first feature, It is further equipped with a blue light source that emits blue light with a peak wavelength of 410 nm or higher and 450 nm or lower.

[0027] In other words, the light-emitting device includes a blue light source in addition to the excitation light source. The blue light emitted from the blue light source is not excited by the phosphor and does not function as excitation light. The blue light emitted from the blue light source passes through the phosphor without being converted by it and is emitted from the light-emitting device.

[0028] <<Characteristic 9>> The ninth characteristic is, as mentioned in the eighth characteristic, The aforementioned blue light source is an LED or a semiconductor laser.

[0029] <<Feature #10>> The tenth feature is, in the first feature, The predetermined spectral distribution is The spectral region includes a discontinuous region within the range of 470 nm or more and 540 nm or less. The spectrum includes a discontinuous region within the range of 560 nm or more and 610 nm or less.

[0030] <<Feature #11>> The eleventh feature is, in the first feature, The excitation light source is an LED or a semiconductor laser.

[0031] <<Feature #12>> The twelfth feature is, in the first feature, The phosphor is formed by mixing the fluorescent substance with a resin. The phosphor is arranged so that excitation light emitted from the excitation light source can be incident on it.

[0032] In the twelfth characteristic, a phosphor is formed by mixing a fluorescent substance with a resin. The fluorescent substance is mixed with a liquid resin, and after the fluorescent substance is dispersed (uniformly) within the resin, it is solidified to become a solid phosphor. Excitation light emitted from an excitation light source illuminates the phosphor and is incident on the phosphor.

[0033] <<Feature #13>> The 13th characteristic is, in the first characteristic, The phosphor is formed by coating the fluorescent substance onto a light-transmitting member. The phosphor is arranged so that excitation light emitted from the excitation light source can be incident on it.

[0034] In the 13th feature, a phosphor is formed by coating a light-transmitting member having a certain shape, such as a transparent sheet or film, with a fluorescent substance dispersed in a solvent. The excitation light emitted from the excitation light source illuminates the phosphor and is incident on the phosphor.

[0035] <<Feature #14>> The 14th feature is, in the first feature, The phosphor is formed by coating the fluorescent material onto a reflective member. The phosphor is arranged so that excitation light emitted from the excitation light source can be incident on it.

[0036] In the 14th feature, a phosphor is formed by coating a reflective material having a certain shape, such as a mirror or metal that reflects light, with a fluorescent substance dispersed in a solvent. Excitation light emitted from an excitation light source illuminates the phosphor and is incident on the phosphor.

[0037] <<<<Details of this embodiment>>>> The embodiments will be described below with reference to the drawings.

[0038] <<<<First Embodiment>>>> In the first embodiment, the phosphor 160 has a structure in which it is in close contact with the light-emitting surface 102a of the excitation light source 100a. On the other hand, in the second and third embodiments, which will be described later, the phosphors 260 and 360 are positioned at a distance from the light-emitting surface 102a of the excitation light source 100a, which is different from the phosphor 160 of the first embodiment.

[0039] <<<Light-emitting device 10>>> Figure 1 is a cross-sectional view showing the configuration of the light-emitting device 10 according to the first embodiment. Figure 2 is a perspective view showing the overall configuration of the light-emitting device 10 according to the first embodiment.

[0040] The light-emitting device 10 mainly comprises a solid-state light source 100 (excitation light source 100a and blue light source 100b), a substrate 140, and a phosphor 160.

[0041] <<<Solid-state light source 100>>> The solid-state light source 100 emits light with wavelengths within a range that includes a predetermined peak wavelength when powered. The solid-state light source 100 can be, for example, an LED or a laser diode. The solid-state light source 100 may be a single light-emitting element such as an LED chip or a laser diode chip (for example, a chip-on-board), a packaged version (for example, an SMD package), or a modularized version. It can be appropriately selected and used depending on the desired balance of focusing characteristics and intensity, and ease of mounting to the substrate 140 described later. Furthermore, other solid-state light sources may be provided in order to emit light with a desired spectral distribution from the light-emitting device 10.

[0042] At least one excitation light source 100a and at least one blue light source 100b are arranged on the surface 142 of the substrate 140. The excitation light source 100a and the blue light source 100b are spaced apart by an interval d. The excitation light source 100a and the blue light source 100b are arranged so that their optical axes are parallel. In the examples shown in Figures 1 and 2, multiple excitation light sources 100a and multiple blue light sources 100b are arranged alternately, one at a time, along a straight line. Note that in addition to the configuration in which multiple excitation light sources 100a and multiple blue light sources 100b are arranged alternately, a predetermined number of them may also be arranged alternately. The number and arrangement of multiple excitation light sources 100a and multiple blue light sources 100b can be appropriately determined according to the size and shape of the object to be illuminated.

[0043] <<Excitation light source 100a>> The excitation light source 100a emits excitation light with a peak wavelength of 340 nm or more and 410 nm or less. The excitation light has a peak wavelength that falls within the range of 340 nm or more and 410 nm or less. The excitation light source 100a can be an LED or a semiconductor laser, etc. The excitation light source 100a has an emission surface 102a. Excitation light is emitted from the emission surface 102a.

[0044] <<Blue light source 100b>> The blue light source 100b emits blue light with a peak wavelength of 410 nm or more and 450 nm or less. The blue light has a peak wavelength that falls within the range of 410 nm or more and 450 nm or less. The blue light source 100b can be an LED or a semiconductor laser, etc. The blue light source 100b has a light-emitting surface 102b. Excitation light is emitted from the light-emitting surface 102b.

[0045] The light-emitting surface 102a of the excitation light source 100a and 102b of the blue light source 100b are positioned with the substrate 140 behind them. The light emitted from the light-emitting surfaces 102a and 102b travels away from the substrate 140 and towards the phosphor 160.

[0046] Both the excitation light source 100a and the blue light source 100b have electrodes (not shown) and are electrically connected to conductive wiring formed on the substrate 140. The excitation light source 100a and the blue light source 100b are powered via conductive wiring (not shown) formed on the substrate 140.

[0047] <<Substrate 140>> The substrate 140 is a component having a substantially flat (thin plate) shape. The substrate 140 extends in a planar manner. The substrate 140 is large enough to accommodate multiple excitation light sources 100a and multiple blue light sources 100b placed side by side.

[0048] The substrate 140 is preferably made of a material with high thermal conductivity, such as a metal substrate like aluminum, for heat dissipation. However, the substrate 140 is not limited to this and may be made of resin, ceramics, or the like.

[0049] The substrate 140 has a front surface 142 and a back surface 144 opposite to the front surface 142. The front surface 142 is the surface facing the phosphor 160. Conductor wiring (not shown) is formed on the front surface 142 and the back surface 144. The conductive wiring is an electrical conductor for supplying and controlling power to the excitation light source 100a and the blue light source 100b. Alternatively, power to the excitation light source 100a and the blue light source 100b may be supplied by connecting lead wires or the like, instead of forming conductive wiring on the front surface 142 or the back surface 144 of the substrate 140.

[0050] <<Phosphor 160>> The phosphor 160 contains fluorescent particles (not shown), which are fluorescent substances. The fluorescent particles are excited by excitation light having a predetermined peak wavelength and emit light with a wavelength longer than the peak wavelength (for example, light close to infrared light).

[0051] <Fluorescent particles (fluorescent substances)> Specifically, the excitation light source 100a emits light having a peak wavelength in the range of 340 nm or more and 410 nm or less. The light emitted from the excitation light source 100a is used as excitation light, and the excited fluorescent particles are converted to emit long-wavelength light. For example, the same fluorescent particles used in three-wavelength fluorescent lamps are used. Specifically, as fluorescent particles, narrow-band red phosphor KSF (K2SiF6:Mn4+) and "YOX" (Y2O3:Eu) are used. 3+ ) and other narrowband green phosphors such as InP quantum dot phosphors and "CAT" (CeMgAl 11 O 19 :Tb 3+ ), narrowband blue phosphor "BAM" (BaMgAl 10 O 17 :EU 2+ ) and the like can be used.

[0052] The phosphor 160 contains two types of fluorescent particles: fluorescent particles that emit green visible light and fluorescent particles that emit red visible light, using the light emitted from the excitation light source 100a as excitation light. Furthermore, the phosphor 160 may also contain three types of fluorescent particles: fluorescent particles that emit green visible light, fluorescent particles that emit red visible light, and fluorescent particles that emit blue visible light, using the light emitted from the excitation light source 100a as excitation light. The types of fluorescent particles contained in the phosphor 160 can be appropriately determined according to the wavelength of the light emitted from the excitation light source 100a and the wavelength of the light converted by the fluorescent particles.

[0053] Even when using solid-state light sources such as excitation light source 100a and blue light source 100b, the spectrum of a three-wavelength fluorescent lamp can be reproduced almost perfectly by using the same phosphors as those used in fluorescent lamps.

[0054] Furthermore, it is preferable to use narrowband phosphors as fluorescent particles. Narrowband phosphors have a narrow spectral width, high color purity, and high wavelength independence, making it easier to form interference fringes.

[0055] <Resin> The phosphor 160 according to the first embodiment has a form in which fluorescent particles are mixed with a resin and molded to have a certain shape. The resin is liquid when the fluorescent particles are mixed, and solidifies after the fluorescent particles are sufficiently dispersed to form the phosphor 160. The resin should be able to sufficiently disperse the fluorescent particles when liquid, and when solidified, transmit light and stably maintain a certain shape. Furthermore, it is preferable that the resin has heat resistance. The resin in which the fluorescent particles are mixed and sufficiently dispersed is called the phosphor resin. By sufficiently dispersing the fluorescent particles in the resin, the density of fluorescent particles can be made constant throughout the phosphor 160.

[0056] <<Enclosing character 120>> The surrounding body 120 is a partition or wall that defines the area into which the liquid phosphor resin is poured. As shown in Figure 2, the surrounding body 120 is formed on the substrate 140 so as to surround the plurality of excitation light sources 100a and the plurality of blue light sources 100b arranged on the substrate 140 along the surface 142. The surrounding body 120 has a low-profile rectangular tube shape.

[0057] <Formation of phosphor 160 1> Liquid phosphor resin is poured into the inner region surrounded by the surrounding body 120. The poured phosphor resin is dammed up by the surrounding body 120, and the inner region surrounded by the surrounding body 120 is filled with liquid phosphor resin. When the phosphor resin solidifies in the filled state, the phosphor resin has a certain shape corresponding to the surrounding body 120, the substrate 140, and the excitation light source 100a and blue light source 100b provided on the substrate 140.

[0058] In this way, a phosphor 160 having a specific shape is formed. The phosphor 160 is formed in close contact with both the upper surface (light-emitting surface 102a and 102b) and the side surface of the excitation light source 100a and the blue light source 100b (see Figure 1(a)). Furthermore, as shown in Figure 1(a), the phosphor 160 is also formed in close contact with the surface 142 of the substrate 140. The approximate thickness of the phosphor 160 is determined by the height of the surrounding material 120. Note that the surrounding material 120 may be removed from the substrate 140 after the phosphor 160 has been formed.

[0059] <Formation of phosphor 160 2> In addition to the formation method 1 of the phosphor 160 described above, the phosphor 160 can also be formed using a mold having a certain shape. For example, a thin plate-shaped or sheet-shaped phosphor 160 can be formed by pouring liquid phosphor resin into a mold having a thin plate-shaped or sheet-shaped shape. When this phosphor 160 is used, the phosphor 160 can be attached in close contact with the upper surfaces (light-emitting surfaces 102a and 102b) of the excitation light source 100a and the blue light source 100b (see Figure 1(b)). As shown in Figure 1(b), the phosphor 160 is positioned at a distance from the surface 142 of the substrate 140.

[0060] Furthermore, in the case of phosphors 160 in the form of thin plates or sheets, it is preferable that they be flexible. They can be placed in close contact with the light-emitting surface 102a of the excitation light source 100a and the light-emitting surface 102b of the blue light source 100b. The shape of the mold can be appropriately determined according to the desired shape of the phosphor 160.

[0061] According to the first embodiment of the phosphor 160, the phosphor 160 can be provided in close contact with at least the light-emitting surface 102a of the excitation light source 100a and the light-emitting surface 102b of the blue light source 100b. By immediately directing the excitation light emitted from the excitation light source 100a onto the phosphor 160, it can be efficiently converted into fluorescence and emit fluorescence. In addition, the blue light emitted from the blue light source 100b can be immediately directed onto the phosphor 160, allowing light to be efficiently emitted from the light-emitting device 10.

[0062] <<<<Second Embodiment>>>> In the second embodiment, the phosphor 260 is positioned at a location separated from the light-emitting surface 102a of the excitation light source 100a.

[0063] <<<Light-emitting device 20>>> Figure 3 is a cross-sectional view showing the configuration of the light-emitting device 20 according to the second embodiment. Figure 4 is a perspective view showing the overall configuration of the light-emitting device 20 according to the second embodiment.

[0064] The light-emitting device 20 of the second embodiment differs from the light-emitting device 10 of the first embodiment in that it has a phosphor 260. The differences from the light-emitting device 10 of the first embodiment will be described below.

[0065] <<Phosphor 260>> The phosphor 260, like the phosphor 160 according to the first embodiment, contains fluorescent particles (not shown) which are fluorescent substances. The type of fluorescent particles is the same as that of the phosphor 160.

[0066] The phosphor 260 is positioned at a height h away from the substrate 140. The phosphor 260 has a flat, thin plate shape. The phosphor 260 is supported by a support member (not shown) and positioned parallel to the substrate 140.

[0067] <Light-transmitting member 270> The phosphor 260 has a light-transmitting member 270. The light-transmitting member 270 has a lower surface 272 and an upper surface 274. A phosphor resin is applied to the lower surface 272, and the light-transmitting member 270 coated with the phosphor resin functions as the phosphor 260. The light-transmitting member 270 can be any material that transmits light. For example, the light-transmitting member 270 can be glass, alumina, resin, etc.

[0068] Furthermore, a material that does not easily transmit light below 400 nm may be used as the light-transmitting member 270. Specifically, float glass plates or glass with long-pass filters can be used as the light-transmitting member 270. Light transmitted through the phosphor 160 immediately enters the lower surface 272 of the light-transmitting member 270, where light below 400 nm is attenuated, and only light with wavelengths longer than 400 nm is emitted from the upper surface 274. With this configuration, light below 400 nm, which is harmful to the human body, is not emitted from the light-emitting device 20. It is possible to provide a light-emitting device that emits light almost equivalent to the spectrum of a three-wavelength fluorescent lamp while blocking light below 400 nm, which is harmful to the human body, and without using mercury.

[0069] Since the light transmitted through the phosphor 260 immediately enters the lower surface 272, all of the light transmitted through the phosphor 260 can be guided to the light-transmitting member 270. In this way, it is possible to prevent light from leaking to the outside of the light-emitting device 20 from between the phosphor 260 and the light-transmitting member 270.

[0070] <<<<Third Embodiment>>>> In the third embodiment, the phosphor 360 is positioned at a location separated from the light-emitting surface 102a of the excitation light source 100a.

[0071] <<<Light-emitting device 30>>> Figure 5 is a cross-sectional view showing the configuration of the light-emitting device 30 according to the third embodiment. Figure 5(a) is a cross-sectional view showing the light-emitting device 30 cut along its longitudinal direction, and Figure 5(b) is a cross-sectional view showing the light-emitting device 30 cut along its short direction. Figure 6 is a perspective view showing the overall configuration of the light-emitting device 30 according to the third embodiment.

[0072] The light-emitting device 30 of the third embodiment differs from the light-emitting device 10 of the first embodiment and the light-emitting device 20 of the second embodiment in that the phosphor 360 is positioned at an angle with respect to the substrate 140. The differences between the light-emitting device 10 of the first embodiment and the light-emitting device 20 of the second embodiment will be described below.

[0073] <<Phosphor 360>> The phosphor 360, like the phosphor 160 of the first embodiment and the phosphor 260 of the second embodiment, contains fluorescent particles (not shown) which are fluorescent substances. The type of fluorescent particles is the same as that of the phosphors 160 and 260.

[0074] The phosphor 360 is positioned away from the substrate 140 and at an angle to the substrate 140. The phosphor 360 has a flat, thin plate-like shape.

[0075] <Reflective material 370> The phosphor 360 has a reflective member 370. The reflective member 370 has a reflective surface 372. A phosphor resin is applied to the reflective surface 372, and the reflective member 370 coated with the phosphor resin functions as the phosphor 360. The reflective member 370 can be any member that reflects light. For example, the light-transmitting member 270 can be a mirror, metal itself, or glass with a metal vapor-deposited on it.

[0076] As shown in Figures 5(b) and 6, the phosphor 360 is positioned at an angle of approximately 45 degrees with respect to the plane on which the substrate 140 extends (for example, the horizontal direction). The phosphor 360 is held in this inclined state by a predetermined support (not shown).

[0077] By using the phosphor 360, the light emitted from the excitation light source 100a can be used as excitation light to emit green visible light, red visible light, etc., and the direction in which the light such as green visible light and red visible light propagates can be controlled according to the tilt of the phosphor 360.

[0078] The angle of the substrate 140 with respect to the surface on which it extends (for example, the horizontal direction) can be appropriately determined according to the position of the object to be illuminated and the position of the light-emitting device 30.

[0079] <<<<Example of the spectral distribution of light emitted from the light-emitting device 10>>>> Below, we show the spectral distribution of light emitted from five prototype light-emitting devices 10. Figure 7 is a representative graph showing the spectral distribution of one of the five light-emitting devices 10. Figure 8 is a graph showing the spectral distributions of all five light-emitting devices 10 superimposed. Figures 7 and 8 are graphs with wavelength on the horizontal axis and intensity on the vertical axis. Note that the excitation light emitted from the excitation light source 100a is the spectral distribution when emitted from the light-emitting device 10 without being filtered or otherwise cut off.

[0080] As shown in Figure 7, the light-emitting device 10 emits: Excitation light and, Blue light and, The first fluorescence is green visible light, The second fluorescence is red visible light, It is uttered.

[0081] <Excitation light> Excitation light with a peak P0 at approximately 367 nm is emitted from the excitation light source 100a. As shown in Figure 7, the intensity at peak P0 is defined as M0.

[0082] <Blue light> Blue light with a peak P1 at approximately 440 nm is emitted from the blue light source 100b.

[0083] <The first fluorescence is green visible light> The excitation light from the excitation light source 100a is converted by the phosphor 160, emitting green visible light, which is a first fluorescence with a peak P2 at approximately 540 nm.

[0084] <The second type of fluorescence is red visible light> The excitation light from the excitation light source 100a is converted by the phosphor 160, emitting red visible light, which is a second fluorescence with a peak P3 at approximately 617 nm.

[0085] The light emitted from the light-emitting device 10 has a spectral distribution that is distributed in the range of approximately 320 nm or more and 700 nm or less.

[0086] <<Discontinuous regions DR1, DR2, and DR3>> Furthermore, as shown in Figure 7, the light emitted from the light-emitting device 10 has three discontinuous regions DR1, DR2, and DR3.

[0087] <First discontinuity region DR1> The first discontinuity region DR1 is formed in the range of approximately 405-430 nm. The maximum intensity M1 in the first discontinuity region DR1 is less than one-tenth of the intensity M0 at the excitation light peak P0. That is, in the first discontinuity region DR1, the relationship M0 / 10 > M1 holds true with respect to intensity.

[0088] <Second discontinuity region DR2> The second discontinuity region DR2 is formed in the range of approximately 470-540 nm. The maximum intensity M2 in the second discontinuity region DR2 is less than one-tenth of the intensity M0 at the excitation light peak P0. That is, in the second discontinuity region DR2, the relationship M0 / 10 > M2 holds true with respect to intensity.

[0089] <Third discontinuity region DR3> The third discontinuity region, DR3, is formed in the range of approximately 560-610 nm. The maximum intensity M3 in the third discontinuity region DR3 is less than one-tenth of the intensity M0 at the excitation light peak P0. That is, in the third discontinuity region DR3, the relationship M0 / 10 > M3 holds true with respect to intensity.

[0090] Thus, in each of the three discontinuous regions DR1, DR2, and DR3, the maximum intensities M1, M2, and M3 are less than one-tenth of the intensity M0 at the peak P0 of the excitation light. In this way, in the three discontinuous regions DR1, DR2, and DR3, the light intensity is lower than a predetermined intensity. The predetermined intensity can be appropriately determined according to the content of the inspection, such as unevenness in film thickness. A region where the light intensity is lower than a predetermined intensity can be defined as a discontinuous region.

[0091] Thus, the light emitted from the light-emitting device 10 has three spectral regions in the range of 320 nm or more and 700 nm or less, where the light intensity is discontinuous.

[0092] <<Half-width HW1, HW2, HW3>> As shown in Figure 7, peak P1 has a full width at half maximum (FWHM) HW1, peak P2 has a FWHM HW2, and peak P3 has a FWHM HW3.

[0093] <<When it emits green visible light, which is the first type of fluorescence>> Furthermore, from the light-emitting device 10, Excitation light and, The first fluorescence is green visible light, When configured to emit such emission, a discontinuous region can be formed in the range of approximately 405 to 530 nm (not shown).

[0094] <<When it emits a second type of fluorescence, red visible light>> As shown in Figure 7(c), from the light-emitting device 10, Excitation light and, The second fluorescence is red visible light, When configured to emit such emission, a discontinuous region can be formed in the range of approximately 405 to 560 nm (not shown).

[0095] <<<Variation in peak wavelength and full width at half maximum>>> Figure 8 is a graph showing the superimposed spectral distributions of five light-emitting devices 10. Note that the five light-emitting devices 10 shown in Figure 8 were manufactured from the same batch. Therefore, except for the excitation light peak P0, all peaks P1, P2, P3 and half-widths HW1, HW2, HW3 for blue light, green visible light, and red visible light overlapped.

[0096] However, if the light-emitting device 10 is manufactured using LED chips from different lots and phosphors from different lots, the peaks P1, P2, P3 and the full widths HW1, HW2, HW3 will naturally vary.

[0097] <<Regarding the half-value range>> As the half-width (FWHM) narrows, the purity of the color increases, and variations in film thickness become more likely to appear as interference fringes. As an extreme example, if the FWHM of green is wide, it will cover a range from blue-green to yellow-green, making the difference between green and blue or red unclear. In contrast, if the FWHM is narrow, blue-green and yellow-green components are not included, allowing for higher contrast with blue and red, and making interference fringes more likely to appear.

[0098] <<Regarding the peak location>> Furthermore, as the variation in peak position decreases, the color shifts of blue, green, and red also decrease, thus reducing individual differences in the light source used for inspection and stabilizing the color variation of interference fringes. For example, if the green peak position shifts towards shorter wavelengths, a color containing blue-green is produced, and if it shifts towards longer wavelengths, a color containing yellow-green is produced. Even if individual differences occur, the same color will be emitted as long as the peak position does not shift.

[0099] <<The range of variation that produces interference fringes>> The acceptable range of variation for causing interference fringes due to variations in film thickness is as follows:

[0100] <Preferred peak wavelength and full width at half maximum> For the blue light, peak P1 is between 430 nm and 460 nm, and the full width at half maximum (FWHM) HW1 is between 15 nm and 35 nm. For the green light, peak P2 is between 530 nm and 560 nm, and the FWHM HW2 is between 5 nm and 15 nm. For the red light, peak P3 is between 610 nm and 640 nm, and the FWHM HW3 is between 5 nm and 15 nm. In this way, at least two discontinuous regions with discontinuous intensity are formed between the three peaks P1, P2, and P3, making it possible to generate and inspect interference fringes.

[0101] <Preferred peak wavelength and full width at half maximum> For the blue light, peak P1 is between 445 nm and 455 nm, and the full width at half maximum (FWHM) HW1 is between 15 nm and 30 nm. For the green light, peak P2 is between 540 nm and 550 nm, and the FWHM HW2 is between 5 nm and 10 nm. For the red light, peak P3 is between 610 nm and 620 nm, and the FWHM HW3 is between 5 nm and 10 nm. In this way, at least two discontinuous regions with discontinuous intensity are formed between the three peaks P1, P2, and P3, making it possible to generate and inspect interference fringes.

[0102] <Best peak wavelength and full width at half maximum> For the blue light, peak P1 is between 445 nm and 450 nm, and the full width at half maximum (FWHM) HW1 is between 15 nm and 30 nm. For the green light, peak P2 is between 545 nm and 550 nm, and the FWHM HW2 is between 5 nm and 10 nm. For the red light, peak P3 is between 615 nm and 620 nm, and the FWHM HW3 is between 5 nm and 10 nm. In this way, at least two discontinuous regions with discontinuous intensity are formed between the three peaks P1, P2, and P3, generating interference fringes that can be used for inspection.

[0103] As the half-widths HW1, HW2, and HW3 narrow, the purity of the color increases, and interference fringes become more easily generated. Also, as the variation in the positions of peaks P1, P2, and P3 decreases, the color of the interference fringes, which is affected by individual differences in the inspection light source, becomes more stable.

[0104] <<<<Scope of the Embodiment>>>> As described above, the first to third embodiments have been presented. However, the descriptions and drawings that constitute part of this disclosure should not be understood as limiting. Various embodiments not described herein are included. [Industrial applicability]

[0105] It is suitable for devices that inspect the thickness of films and optical sheets, as well as optical inspection devices that use spectral interference. [Explanation of Symbols]

[0106] 10, 20, 30 Light-emitting devices 100a Excitation light source 100b blue light source 160,260,360 phosphors

Claims

1. An excitation light source that emits excitation light with a peak wavelength of 340 nm or higher and 410 nm or lower, A blue light source that emits blue light with a peak wavelength of 410 nm or higher and 450 nm or lower, A phosphor comprising at least one type of fluorescent substance, wherein the phosphor is arranged in the direction of propagation of the excitation light emitted from the excitation light source, The phosphor is excited by the excitation light, and the light emitted from the phosphor has a predetermined spectral distribution in the range of 320 nm or more and 700 nm or less. The blue light emitted from the blue light source passes through the phosphor without being converted by the phosphor and is emitted from the light-emitting device. The predetermined spectral distribution is A first discontinuous region formed in the range of approximately 405 nm or more and 430 nm or less, A second discontinuous region formed in the range of approximately 470 nm or more and 540 nm or less, A third discontinuous region is formed in the range of approximately 560 nm or more and 610 nm or less, Includes, A light-emitting device in which, with M0 being the intensity at the peak of the excitation light, the maximum intensity M1 in the first discontinuity region, the maximum intensity M2 in the second discontinuity region, and the maximum intensity M3 in the third discontinuity region are all one-tenth or less of M0.

2. The light-emitting device according to claim 1, wherein the aforementioned fluorescent material is of two types.

3. The light-emitting device according to claim 1, wherein the aforementioned fluorescent material is of three types.

4. The light-emitting device according to claim 1, wherein the blue light source is an LED or a semiconductor laser.

5. The light-emitting device according to claim 1, wherein the excitation light source is an LED or a semiconductor laser.

6. The phosphor is formed by mixing the fluorescent substance with a resin. The light-emitting device according to claim 1, wherein the phosphor is arranged so that excitation light emitted from the excitation light source can be incident on it.

7. The phosphor is formed by coating the fluorescent substance onto a light-transmitting member. The light-emitting device according to claim 1, wherein the phosphor is arranged so that excitation light emitted from the excitation light source can be incident on it.

8. The phosphor is formed by coating the fluorescent material onto a reflective member. The light-emitting device according to claim 1, wherein the phosphor is arranged so that excitation light emitted from the excitation light source can be incident on it.

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