Lighting light source

Abstract

Illumination light source (1), comprising: a light-emitting solid element (11); and a wavelength converter (12), wherein the wavelength converter (12) includes a wavelength conversion material which performs a wavelength conversion of a portion of the light emitted by the light-emitting solid element (11) and emits light of a different wavelength, the wavelength converter (12) emits a composite light consisting of the light emitted by the light-emitting solid element (11) and the light emitted by the wavelength conversion material, a correlated color temperature of the composite light lies in a range of 5700 K to 7100 K, a spectral distribution of the composite light exhibiting a first peak wavelength in a range of 430 nm to 470 nm, a second peak wavelength in a range of 490 nm to 540 nm, a third peak wavelength in a range of 600 nm to 640 nm, a first minimum value of intensity between the first peak wavelength and the second peak wavelength, and a second minimum value between the second peak wavelength and the third peak wavelength. a difference between the second peak value, which is of intensity in the second peak wavelength, and the first minimum value lies in a range of 30% to 55% with respect to the second peak value, a difference between the second peak and the second minimum value is in the range of 20% to 45% with respect to the second peak, the light-emitting solid element (11) is a blue light-emitting diode with a peak wavelength in the range of 430 nm to 470 nm, and The wavelength conversion material includes a blue-green fluorescent material with a peak wavelength in the range of 490 nm to 540 nm, a yellow fluorescent material with a peak wavelength in the range of 530 nm to 600 nm, and a red fluorescent material with a peak wavelength in the range of 600 nm to 670 nm.

Description

Background of the invention 1. Field of the invention

[0001] The present disclosure relates to an illumination light source that can suppress melatonin secretion in a biological body. 2. Description of the state of the art

[0002] The publication of the unexamined Japanese patent JP 2011072388 A, for example, discloses a lighting light source which produces an effect that suppresses melatonin secretion in order to promote the adaptation of the biorhythm and wakefulness of the biological body.

[0003] US Patent 2002 / 0070681 A1 describes an LED lamp containing blue and red LEDs and a phosphor. The blue LED emits light at a wavelength in the blue wavelength range. The red LED emits light at a wavelength in the red wavelength range. The phosphor is excited by the emission from the blue LED to emit luminescence with an emission spectrum in an intermediate wavelength range between the blue and red wavelength ranges.

[0004] US 2012 / 0256560 A1 describes a package for a light-emitting device comprising a packaging body; a first light-emitting device mounted on the packaging body that emits light of a specific color; a second light-emitting device mounted on the packaging body adjacent to the first light-emitting device that adjusts the amount of light according to an applied current value in order to control a color temperature and that emits orange light; and a resin part that seals the first and second light-emitting devices and contains at least one or more types of phosphors. Summary of the invention

[0005] An illumination light source according to one aspect of the present disclosure comprises a light-emitting solid element and a wavelength converter. The wavelength converter comprises a wavelength conversion material that partially performs a wavelength conversion of the light emitted by the light-emitting solid element and emits light with a different wavelength. The wavelength converter emits composite light consisting of the light emitted by the light-emitting solid element and the light emitted by the wavelength conversion material. A correlated color temperature of the composite light lies in the range of 5700 K to 7100 K. A spectral distribution of the composite light exhibits a first peak or maximum wavelength in the range of 430 nm to 470 nm, a second peak or maximum wavelength in the range of 490 nm to 540 nm, and a third peak or maximum wavelength in the range of 490 nm to 540 nm.The maximum wavelength is in the range of 600 nm to 640 nm. The spectral distribution of the composite light exhibits a first minimum intensity value between the first peak wavelength and the second peak wavelength, and a second minimum intensity value between the second peak wavelength and the third peak wavelength. The difference between the second peak (maximum value) and the first minimum value is in the range of 30% to 55% relative to the second peak value. The difference between the second peak value and the second minimum value is in the range of 20% to 45% relative to the second peak value. The light-emitting solid element is a blue light-emitting diode with a peak wavelength in the range of 430 nm to 470 nm.The wavelength conversion material includes a blue-green fluorescent material with a peak wavelength in the range of 490 nm to 540 nm, a yellow fluorescent material with a peak wavelength in the range of 530 nm to 600 nm, and a red fluorescent material with a peak wavelength in the range of 600 nm to 670 nm.

[0006] Accordingly, the melatonin secretion suppression effect of a biological body can be improved in the lighting light source when the light source color is daylight color. Brief description of the drawing Fig. Figure 1 is an illustrative view showing a spectral distribution of an illumination light source according to a preferred embodiment of the present disclosure. Fig. Figure 2 is a schematic sectional view illustrating the light source module of the preferred embodiment. Fig.Figure 3 is an explanatory view illustrating an action function of melatonin secretion suppression and a relative luminance function. Fig. Figure 4 is an explanatory view to illustrate a relationship between a biological effect and a conversion efficiency of a blue-green fluorescent material. Fig. Figure 5 is an explanatory view showing a characteristic curve of a wavelength conversion material in the illumination light source of the preferred embodiment. Fig. Figure 6 is a schematic sectional view illustrating an illumination light source according to a first modification of the preferred embodiment. Fig. Figure 7 is a schematic sectional view illustrating an illumination light source according to a second modification of the preferred embodiment. Fig.Figure 8 shows a spectral distribution of composite light emitted by the illumination light source of Example 1. Fig. Figure 9 shows a spectral distribution of composite light emitted by an illumination light source of Example 2. Fig. Figure 10 shows a spectral distribution of composite light emitted by an illumination light source of Example 3. Fig. Figure 11 shows a spectral distribution of composite light emitted by an illumination light source of comparison example 1. Fig. Figure 12 shows a spectral distribution of composite light emitted by an illumination light source of comparison example 2. Fig. Figure 13 shows a spectral distribution of composite light emitted by an illumination light source of comparison example 3. Fig.Figure 14 shows a spectral distribution of composite light emitted from an illumination light source of comparison example 4. Fig. Figure 15 shows a spectral distribution of composite light emitted by an illumination light source of comparison example 5. Detailed description of the preferred embodiment

[0007] A problem with the light source module of the related technology is described before the description of a preferred embodiment. In the illumination light source disclosed in the publication of unexamined Japanese Patent No. 2011-72388, a correlated color temperature exceeds 7100 K, and an illuminated room appears slightly more blue to a user when the light source is used in an ordinary indoor space. Generally, the melatonin secretion suppression effect of a biological body deteriorates when the light source color approaches a low color temperature.

[0008] An illumination light source capable of improving the melatonin secretion suppression effect of the biological body, the optical quality of skin color, and color rendering, regardless of the fact that the light source color is a daylight color, is described below with reference to the drawing. Each of the following preferred embodiments represents a preferred specific example. A numerical value, shape, material, component, arrangement and connection mode of components, process, and process sequence are given in the following preferred embodiments purely by way of example and are not intended to limit the present disclosure.

[0009] Each figure is a schematic representation and is not exact. In the drawing, an essentially identical structure is labelled with the same reference symbol, and any duplicate description is simplified or omitted.

[0010] An illumination light source 1 according to a preferred embodiment of the present disclosure is based on Fig. 1 to 5 described. Fig. Figure 1 is an explanatory view illustrating the spectral distribution of the illumination light source 1. Fig. Figure 2 is a schematic sectional view to illustrate the illumination light source 1. Fig. Figure 3 is an explanatory view illustrating an action function of melatonin secretion suppression and a relative luminance function. Fig. Figure 4 is an explanatory view to illustrate a relationship between a biological effect and a conversion efficiency of a blue-green fluorescent material. Fig. Figure 5 is an explanatory view showing a characteristic curve of a wavelength conversion material in the illumination light source 1.

[0011] As in Fig.As shown in Figure 2, the illumination light source 1 includes a light-emitting solid element 11 and a wavelength converter 12. The wavelength converter 12 includes a wavelength conversion material that partially converts the wavelength of the light emitted by the light-emitting solid element 11 and emits light with a different wavelength. The wavelength converter 12 emits composite light consisting of the light emitted by the light-emitting solid element 11 and the light emitted by the wavelength conversion material. The correlated color temperature of the composite light emitted by the wavelength converter 12 is in the range of 5700 K to 7100 K. As shown in Figure 2, the wavelength conversion material is 11. Fig.As shown in Figure 1, the spectral distribution of the composite light from the illumination source 1 exhibits a first peak or maximum wavelength in the range of 430 nm to 470 nm, a second peak or maximum wavelength in the range of 490 nm to 540 nm, and a third peak or maximum wavelength in the range of 600 nm to 640 nm. The spectral distribution of the composite light from the illumination source 1 includes a first minimum intensity value x1 between the first peak wavelength and the second peak wavelength, and a second minimum intensity value x2 between the second peak wavelength and the third peak wavelength. The difference (X - x1) between a second peak or maximum value X, which is the intensity at the second peak wavelength, and the first minimum value x1 is in the range of 30% to 55% with respect to the second peak value X.A difference (X-x2) between the second peak value X and the second minimum value x2 lies in a range of 20% to 45% with respect to the second peak value X. Therefore, with illumination light source 1, the melatonin secretion suppression effect of the biological body can be improved, even though the light source color is daylight color, and the optical quality of skin color and color rendering can be improved.

[0012] Each component of the lighting light source 1 is described in detail below.

[0013] The light-emitting solid element 11 can, for example, be constructed with a light-emitting diode (LED). The illumination light source 1 is a light source in which the LED is used. The light-emitting solid element 11 can, for example, be constructed with an LED that has a peak wavelength in the wavelength range of 430 nm to 470 nm. This means that the light-emitting solid element 11 can be constructed with a blue LED that has a peak wavelength in the wavelength range of 430 nm to 470 nm. Therefore, the number of wavelength conversion material options for the illumination light source 1 increases with the combination of the LED and the wavelength conversion material.

[0014] The blue LED can be constructed with an LED chip that emits blue light. For example, a blue gallium nitride LED chip can be used as the LED chip that emits the blue light. A package in which the LED chip is housed can, for example, be used as the LED. One or more LED chips can be housed in the package. The light-emitting solid element 11 is not limited to the LED. The light-emitting solid element 11 can, for example, be constructed with a laser diode (LD).

[0015] The LED chip can be used in planar dimensions of, for example, 0.3 mm x 0.3 mm, 0.45 mm x 0.45 mm, or 1 mm x 1 mm. The planar shape of the LED chip is not limited to a square form. For example, the LED chip can also be rectangular. A rectangular LED chip measuring 0.5 mm x 0.24 mm in planar dimension can be used, for instance.

[0016] The light-emitting solid element 11 includes a first electrode (not shown) and a second electrode (not shown). One of the first and second electrodes is used as the anode electrode, while the other is used as the cathode electrode.

[0017] The illumination light source 1 includes a mounting plate 13 on which the light-emitting solid element 11 is mounted. When the illumination light source 1 includes the mounting plate 13, an LED module can be formed. The light-emitting solid element 11 is mounted on the mounting plate 13.

[0018] The mounting plate 13 includes a holding body 14 and a wiring part (not shown) which is held by the holding body 14 and is electrically connected to the light-emitting solid element 11.

[0019] The wiring part includes first and second conductors (not shown) which are electrically connected to the first and second electrodes of the light-emitting solid element 11.

[0020] The retaining body 14 of the mounting plate 13 is designed in the form of a flat plate. The shape of the retaining body 14 is not limited to the flat plate shape. For example, a recess in which the light-emitting solid element 11 is housed can be formed in the retaining body 14.

[0021] The outer shape of the retaining body 14 is rectangular. Alternatively, the outer shape of the retaining body 14 can be, for example, polygonal or circular. The planar size of the retaining body 14 is larger than that of the light-emitting solid element 11.

[0022] There is no specific limitation regarding the number of light-emitting solid elements 11 that can be mounted on the mounting plate 13. For example, a plurality of light-emitting solid elements 11 can be mounted on the mounting plate 13. In the lighting light source 1, a plurality of light-emitting solid elements 11 can be connected in series, in parallel, or in series-parallel.

[0023] Preferably, the wavelength converter 12 consists of a mixture of the wavelength converter material and a visible light-transmitting translucent material, and the wavelength converter 12 covers the light-emitting solid element 11. Therefore, in a case where the LED chip is used as the light-emitting solid element 11, the wavelength converter 12 also acts as a sealing element that seals the light-emitting solid element 11. Although the wavelength converter 12 has a hemispherical shape, the retaining body 14 is not limited to a hemispherical shape. For example, the wavelength converter 12 can have a semi-elliptical shape, a dome shape, or a rectangular parallelepiped shape. The recess in which the light-emitting solid element 11 is housed can be formed in the retaining body 14.In this case, for example, the hemispherical shape, the semi-elliptical shape, the dome shape and the rectangular parallelepiped shape can be used as the shape of the wavelength converter 12.

[0024] In the illumination light source 1, a light-emitting solid element 11 is covered with a wavelength converter 12. Alternatively, a plurality of light-emitting solid elements 11 can be covered with a wavelength converter 12. In this case, the shape of the wavelength converter 12 is preferably adapted based on an arrangement of the plurality of light-emitting solid elements 11. For example, in a case where a plurality of light-emitting solid elements 11 are arranged in a field-like manner in a longitudinal direction of the mounting plate 13 with a long and thin rectangular shape when viewed planar, the wavelength converter 12 can be designed in a semi-cylindrical shape that covers a plurality of the light-emitting solid elements 11.

[0025] A fluorescent material that is excited by the light emitted by the light-emitting solid element 11 and emits light of a color different from the emission color of the light-emitting solid element 11 can be used as a wavelength conversion material. A silicon resin is used as the translucent material. An acrylic resin, glass, and an organic or inorganic hybrid material can be used, for example.

[0026] The composite light emitted by the wavelength converter 12 is a mixture of light emitted by the light-emitting solid element 11 and emitted by the wavelength converter 12 without performing wavelength conversion, and light emitted by the wavelength converter 12 and thereby subjected to wavelength conversion using the wavelength conversion material.

[0027] The composite light from illumination source 1 exhibits correlated color temperatures ranging from 5700 K to 7100 K. The correlated color temperature describes the color of a light source (in this case, illumination source 1). It is the absolute temperature of the blackbody radiation with a chromaticity coordinate closest to the UV chromaticity coordinate of the light source. For example, JIS Z8113:1998 and IEC 60050-845 define the correlated color temperature. The correlated color temperature is also a value obtained through a method for measuring the correlated color temperature as defined in JIS Z8725:1999.The chromaticity coordinate of the blackbody radiation closest to the chromaticity coordinate of the light source is obtained by drawing a perpendicular line from a point on the chromaticity coordinate of the light source to the chromaticity coordinate of CIE 1960 UCS (Uniform Chromaticity Scale). 5700 K is a lower limit of a range of correlated color temperatures (5700 K to 7100 K) of daylight color as defined in JIS Z9112:2012. 7100 K is an upper limit of the correlated color temperature of daylight color and an upper limit of the correlated color temperature of a fluorescent lamp used in the daylight simulator D. 65 as defined in IEC 60050.

[0028] For illumination light source 1, the biological effect calculated from the spectral distribution of the composite light output from wavelength converter 12 using equation (1) to represent the melatonin secretion suppression effect is greater than or equal to 0.85. Biological effect = ∫S(λ)⋅A(λ)dλ∫S(λ)⋅V(λ)dλ

[0029] Here, S(λ) is a spectral distribution of the illumination light source 1 and a function of the wavelength λ. S(λ) can be a relative spectral distribution based on a maximum value of the spectral distribution of the illumination light source 1. For example, JIS Z8113:1998 or IEC 60050-845 define the spectral distribution and the relative spectral distribution.

[0030] A(λ) is an action function of melatonin secretion suppression and a function of wavelength λ. The action function of melatonin secretion suppression is an action-effect curve that suppresses melatonin secretion to promote the adaptation of the circadian rhythm and wakefulness of the biological body, where the action function is a curved line, as represented by the solid line in Fig.Figure 3 illustrates this. Regarding the shape of the action function A(λ) of melatonin secretion suppression, the action function A(λ) is a curve that is convex upwards in a range from approximately 400 nm to approximately 600 nm and exhibits a peak or maximum at a wavelength λ of approximately 464 nm. The action function of melatonin secretion suppression is described, for example, in "Action Spectrum for Melatonin Regulation in Humans: Evidence for a Novel Circadian Photoreceptor" by GC Brainer, published in "The Journal of Neuroscience", August 15, 2001, 21(16), pages 6405 to 6412.

[0031] V(λ) is the relative luminance. λ is the wavelength. A standard relative luminance curve is one represented by a dash-dot line in Fig.Figure 3 is shown. JIS Z8113:1998 or IEC 60050-845 define relative luminance in this way. Preferably, the CIE standard photopic relative luminance is used as the relative luminance.

[0032] The integral wavelength range in the denominator and numerator on the right-hand side of equation (1) can be chosen from the wavelength range of visible light. For example, the integral wavelength range can be chosen from 380 nm to 780 nm. Therefore, equation (1) can be expressed as equation (2). Biological effect = ∫380780S(λ)⋅A(λ)dλ∫380780S(λ)⋅V(λ)dλ

[0033] The shortwavelength limit of the visible light wavelength range falls within a range of 360 nm to 400 nm. The longwavelength limit of the visible light wavelength range falls within a range of 760 nm to 830 nm. Therefore, the integral wavelength range can be selected within a range of 360 nm to 830 nm.

[0034] For illumination light source 1, the preference index of skin color (PS), which is calculated from the spectral distribution of the composite light, is preferably greater than or equal to 80.

[0035] The PS is a value that indicates skin color preference. The PS can be derived based on a process disclosed in "Method for Evaluating Preference of Skin Color of Japanese Woman under Illuminating Light" by Kenjiro Hashimoto et al., published in the "Journal of Illuminating Engineering Institute of Japan," Volume 82, No. 11, page 895, 1998, or in the publication of unexamined Japanese patent No. 11-258047. This means that the PS can be derived using the spectral distribution and chromaticity coordinate of the illumination light source 1 instead of the spectral distribution and chromaticity coordinate of the illumination lamp, in a calculation procedure as described in the aforementioned publications.In the PS calculation procedure, the PS can be calculated using the formula PS = 4 × 5P, after determining a calculated rating value P regarding skin color preference. As described above, the PS is the value that indicates skin color preference. In other words, the PS is the value that indicates the perceived quality of human skin color.

[0036] The value of the PS in light from the daylight simulator D 65 is defined as 80. Accordingly, in illumination light source 1, because the PS of the composite light is greater than or equal to 80, the skin color can be preferably greater than or equal to the light from the daylight simulator D. 65 be.

[0037] For light source 1, if the correlated color temperature is in the range of 5700 K to 7100 K, the biological effect is preferably greater than or equal to 0.85, the PS is greater than or equal to 80, and the average color rendering evaluation number (Ra) is greater than or equal to 90. Therefore, light source 1 can achieve a balance between the biological effect, which adjusts the circadian rhythm, and the optical quality of skin color. For light source module 6500, if the correlated color temperature is greater than or equal to 6500 K, the biological effect is preferably greater than or equal to 0.9, the PS is greater than or equal to 85, and the average color rendering evaluation number (Ra) is greater than or equal to 90.Illumination light source 1 can, for example, be used as a light source during the daytime, starting from the moment a resident or patient wakes up in a nursing home or hospital. In this case, illumination light source 1 suppresses the melatonin secretion of the biological body present in the illumination room, adjusts the circadian rhythm, and creates an environment that improves the optical quality of skin tone. The illumination room refers to a space illuminated by compound light emitted by illumination light source 1. Examples of illumination rooms include a nursing home and a hospital. The circadian rhythm refers to a rhythm that occurs as a behavior or bodily function in human beings on Earth and has a period of approximately 24 hours. The period of approximately 24 hours refers to a period of 24 ± 4 hours or 24 ± 5 ​​hours.

[0038] In the case of the illumination light source 1, the composite light preferably has an average color rendering index (CRI) of 90 or higher. The increased average CRI of the light emitted by the illumination light source 1 can make the color appearance of various substances appear natural. As a result, a comfortable lighting environment can be provided for an elderly person or a hospital patient who is the user. For example, an average CRI of Ra can be determined according to a calculation procedure as defined in JIS Z 8726-1990.

[0039] The spectral distribution of the composite light from the illumination light source 1 exhibits three peaks or maxima, as shown in Fig.Figure 1 shows the spectrum. A first peak or maximum wavelength corresponds to the peak or maximum on the shortest wavelength on the same side as the three peaks and lies in the range of 430 nm to 470 nm. A second peak or maximum wavelength corresponds to the peak or maximum in the middle of the three peaks and lies in the range of 490 nm to 540 nm. A third peak or maximum wavelength corresponds to the peak or maximum on the longest wavelength on the same side as the three peaks and lies in the range of 600 nm to 640 nm. The spectral distribution is shown as an example in Figure 1. Fig. 1 shown, however, the present disclosure does not relate to the spectral distribution of Fig.1 is limited. The spectral distribution can be measured, for example, according to JIS Z8724-1997 4.2 (Spectral Distribution Measurement Method) under a test condition as defined in JIS C8155:2010 5.3 (Test Condition).

[0040] As in Fig. As shown in Figure 1, the first minimum value x1 is a minimum intensity value between the first peak wavelength and the second peak wavelength in the spectral distribution of the composite light. In other words, the first minimum value x1 is the minimum intensity value in the wavelength range between the first peak wavelength and the second peak wavelength and is a value greater than 0. As shown in Figure 1, the first minimum value x1 is the minimum intensity value in the wavelength range between the first peak wavelength and the second peak wavelength and is a value greater than 0. Fig.As shown in Figure 1, the second minimum value x2 is the minimum intensity value between the second and third peak values ​​in the spectral distribution of the composite light. In other words, the second minimum value x2 is the minimum intensity value in the wavelength range between the second and third peak wavelengths and is a value greater than 0.

[0041] The second peak value X is the intensity at the second peak wavelength in the spectral distribution of the composite light.

[0042] As described above, the difference between the second peak value X and the first minimum value x1 lies in a range of 30% to 55% with respect to the second peak value X. In other words, for the illuminating light source 1, the ratio Xa of the difference between the second peak value X and the first minimum value x1 to the second peak value X preferably lies in a range of 30% to 55%, the ratio Xa being determined by equation (3). Xa=(X−x1)X×100

[0043] Preferably, the difference between the second peak value X and the second minimum value x2 lies in a range of 20% to 45% with respect to the second peak value X. In other words, for the illumination light source 1, the ratio Xb of the difference between the second peak value X and the second minimum value x2 to the second peak value X preferably lies in a range of 20% to 45%, wherein the ratio Xb is determined by equation (4). Xb=(X−x2)X×100

[0044] Equation (3) shows that the ratio Xa increases when the first minimum value x1 decreases. If the ratio Xa exceeds 55% at correlated color temperatures from 5700 K to 7100 K, the excessive reduction of the first minimum value x1 leads to a tendency for the conditions that the biological effect is greater than or equal to 0.85, the PS is greater than or equal to 80, and the average color rendering index Ra is greater than or equal to 90 are not met. If the ratio Xa is less than 30%, the ratio Xb tends to increase in comparison due to the excessively high first minimum value x1. Therefore, if the ratio Xa is less than 30%, the average color rendering index Ra tends to decrease to below 90.

[0045] Equation (4) shows that the ratio Xb increases when the second minimum value x2 decreases. If the ratio Xb exceeds 45% at correlated color temperatures from 5700 K to 7100 K, the average color rendering index Ra tends to fall below 90 due to the excessive decrease in the second minimum value x2. If the ratio Xa is less than 20%, the ratio Xa tends to decrease due to the excessive increase in the second minimum value X2. Therefore, if Xb is less than 20%, the biological effect tends to fall below 0.9 at the correlated color temperature of 6500 K. In this case, a sufficient melatonin secretion suppression effect is unlikely.

[0046] With light source 1, if the ratio Xa is in the range of 30% to 55%, while the ratio Xb is in the range of 20% to 45%, the melatonin secretion suppression effect of the biological body can be improved, even though the light source color is daylight. Furthermore, the color rendering is high, and an environment with good optical quality for skin tone can be created. Daylight color is defined in JIS Z9112:2012. The light source color of the LED is categorized into daylight, daylight white, white, warm white, and incandescent bulb color by its chromaticity in an XYZ color system.

[0047] In the illumination light source 1, the light-emitting solid element 11 is preferably a blue LED with a peak wavelength in the range of 430 nm to 470 nm. In the wavelength converter 12, the wavelength conversion material preferably comprises the blue-green fluorescent material with a peak wavelength in the range of 490 nm to 540 nm, the yellow fluorescent material with a peak wavelength in the range of 530 nm to 600 nm, and the red fluorescent material with a peak wavelength in the range of 600 nm to 670 nm. Therefore, with the illumination light source 1, the melatonin secretion suppression effect of the biological body can be improved even though the light source color is daylight.In the illumination light source 1, the peak wavelength of the yellow fluorescent material is particularly preferably in the range of 530 nm to 540 nm in order to obtain the spectral distribution that satisfies the ratios Xa and Xb. In the illumination light source 1, the peak wavelength of the red fluorescent material is particularly preferably in the range of 600 nm to 650 nm in order to obtain the spectral distribution that satisfies the ratios Xa and Xb.

[0048] The blue-green fluorescent material is excited by the light emitted by the light-emitting solid element 11 and emits blue-green light. The yellow fluorescent material is excited by the light emitted by the light-emitting solid element 11 and emits yellow light. The red fluorescent material is excited by the light emitted by the light-emitting solid element 11 and emits red light.

[0049] A fluorescent oxynitride material, a fluorescent halosilicate material, and a fluorescent sulfide material can be cited as examples of blue-green fluorescent materials. (Ca, Eu)8Mg(SiO4)4Cl2 can be cited as an example of a fluorescent halosilicate. A fluorescent YAG (yttrium aluminum garnet) material and a fluorescent oxynitride material can be cited as examples of yellow fluorescent materials. A fluorescent nitride material can be cited as an example of a red fluorescent material. Eu-activated (Sr, Ca)AlSiN3 (commonly called "SCASN") and Eu-activated CaAlSiN3 (commonly called "CASN") can be cited as examples of fluorescent nitride materials.

[0050] Preferably, the full width at half maximum (FWHM) of the emission spectrum of the fluorescent blue-green material lies in the range of 30 nm to 80 nm. Therefore, with the illumination light source 1, the improvement in the intensity of the spectral distribution in the emission spectrum of the blue-green fluorescent material can be limited in the wavelength range that overlaps the emission spectrum of the blue LED. As a result, the elimination of the first minimum value x1 in the spectral distribution can be limited.

[0051] As in Fig. As shown in Figure 4, the biological effect increases when the peak wavelength of the blue-green fluorescent material is shifted towards the shorter wavelength. Conversely, the average color rendering index (Ra) decreases when the peak wavelength of the blue-green fluorescent material is shifted towards the shorter wavelength. As shown in Figure 4, the biological effect increases when the peak wavelength of the blue-green fluorescent material is shifted towards the shorter wavelength. Fig.As shown in Figure 4, the conversion efficiency of the blue-green fluorescent material increases when the biological effect is shifted towards the shorter wavelength. Therefore, for the illumination light source 1, the peak wavelength of the blue-green fluorescent material preferably lies in the range of 510 nm to 520 nm, and the second peak wavelength in the spectral distribution of the composite light lies in the range of 500 nm to 520 nm. Sometimes, the second peak wavelength in the spectral distribution of the composite light is shifted towards the shorter wavelength range by the peak wavelength of the emission spectrum of the blue-green fluorescent material due to the overlap of the emission spectrum of the blue LED with that of the blue-green fluorescent material.

[0052] As described above, the wavelength converter 12 consists of a mixture of the wavelength conversion material and the visible light-transmitting translucent material, and the wavelength converter 12 covers the light-emitting solid element 11. In the case where the wavelength conversion material in the wavelength converter 12 includes the blue-green fluorescent material, the yellow fluorescent material, and the red fluorescent material, the yellow and red fluorescent materials are preferably arranged closer to the light-emitting solid element 11 compared to the blue-green fluorescent material. Therefore, the absorption of light emitted by the blue-green fluorescent material by the yellow or red fluorescent material at the illumination light source 1 can be prevented. As a result, the light extraction efficiency can be improved. Fig.5. The emission spectrum of the blue-green fluorescent material is indicated by a broken line, the absorption spectrum of the yellow fluorescent material is indicated by a dash-dot line, and the absorption spectrum of the red fluorescent material is indicated by a solid line.

[0053] In the case of the illumination light source 1, compared to an area that is comparatively further away from the light-emitting solid element 11 in the wavelength converter 12, an area that is relatively closer to the light-emitting solid element 1 can be designed in such a way that the blending ratio of the yellow and red fluorescent materials increases.

[0054] Fig.Figure 6 is a schematic sectional view illustrating the illumination light source 1b according to a first modification of the preferred embodiment. In the illumination light source 1b, the wavelength converter 12 comprises a first wavelength converter 121 and a second wavelength converter 122. The first wavelength converter 121 consists of a mixture of a first translucent material transmitting visible light, the yellow fluorescent material, and the red fluorescent material, and the first wavelength converter 121 covers the light-emitting solid element 11. The second wavelength converter 122 consists of a mixture of a second translucent material transmitting visible light and the blue-green fluorescent material, and the second wavelength converter 122 is arranged such that it covers the first wavelength converter 121.In the illumination light source 1b, the wavelength converter 12 can be formed by a process of creating the first wavelength converter 121 and a process of creating the second wavelength converter 122. Therefore, the extraction efficiency of the light from the emission of the blue-green fluorescent material in the second wavelength converter 122 can be improved. A silicon resin is used as the first and second translucent materials. For example, an acrylic resin, glass, or an organic or inorganic hybrid material can be used. The first and second translucent materials are not limited to the same material; different materials can also be used as the first and second translucent materials.

[0055] Fig.Figure 7 is a schematic sectional view illustrating an illumination light source 1c according to a second modification of the preferred embodiment. In the light source module 1c, the second wavelength converter 122 covers the first wavelength converter 121 but is not in contact with it. The light source module 1c differs from the light source module 1b only in this respect. Compared to the illumination light sources 1 and 1b, the temperature rise of the blue-green fluorescent material can be limited in the light source module 1c, where the temperature rise of the blue-green fluorescent material is a consequence of the heat generation of the light-emitting solid element 11 and the yellow and red fluorescent materials. Therefore, the light source module 1c can limit the change in the chromaticity of the composite light compared to the illumination light sources 1 and 1b.The gas layer 15 is formed between the second wavelength converter 122 and the first wavelength converter 121. The gas layer 15 can be composed of gas present in a space surrounded by the mounting plate 13 and the first and second wavelength converters 121 and 122. Air and a noble gas can be cited as examples of the gas.

[0056] In general, the conversion efficiency of the blue-green fluorescent material is largely temperature-dependent compared to the yellow and red fluorescent materials. Therefore, the rate of decrease in conversion efficiency tends to be large with increasing temperature. In illumination light source 1c, the second wavelength converter 122, which contains the blue-green fluorescent material, is arranged such that it is separated from the first wavelength converter 121, which contains the yellow and red fluorescent materials. Therefore, the change in the chromaticity of the composite light can be limited compared to illumination light sources 1 and 1b. Example 1

[0057] Example 1 is an illumination light source 1 of the preferred embodiment with the structure of Fig. 2.

[0058] The light-emitting solid element 11 is the blue LED with a peak wavelength of 450 nm. The blue LED is a blue gallium nitride chip. The wavelength converter 12 comprises (Ca, Eu)8Mg(SiO4)4Cl2:Eu 2+ with a peak wavelength of 520 nm, Y3AlsO 12 :Ce 3+ with a peak wavelength of 540 nm and (Sr, Ca)AlSiN3:Eu 2+ with a peak wavelength of 630 nm as the wavelength conversion material. In the illumination light source 1, the mixing ratio of the wavelength conversion materials in the wavelength converter 12 is adjusted such that the color temperature of the composite light is 6500 K and the DUV is equal to 0.

[0059] The DUV is defined in JIS Z8725-1999. The DUV denotes a value a thousand times greater than d. UV multiplied value (DUV = 1000 d UV), where a deviation from the blackbody radiation locus of the CIE-1960-UCS chromaticity coordinate is expressed by the following equation (5). The d UV and the DUV assume a positive value when the chromaticity coordinate of the light source (in this case, light source 1) is located above the blackbody radiation locus, while the d UV and the DUV takes on a negative value when the chromaticity coordinate of the light source (in this case, light source 1) is below the blackbody radiation locus. duv=±{(us−u0)2+(v2−v0)2}1 / 2

[0060] This includes u s and v s The CIE 1960 UCS chromaticity coordinate of the light source. u0 and v0 are coordinates of a point at the blackbody radiation locus in a CIE 1960 UCS chromaticity diagram, where the point is closest to the chromaticity coordinate of the light source.

[0061] Fig.Figure 8 shows a spectral distribution of the compound light emitted by the illumination light source 1 of Example 1. In the spectral distribution of the compound light, the first peak wavelength is 450 nm, the second peak wavelength is 515 nm, and the third peak wavelength is 610 nm. The ratios Xa and Xb are 40% and 35%, respectively, the biological effect is 0.94, the PS is 88, and the average color rendering index Ra is 94. Example 2

[0062] In the case of the illumination light source 1 of Example 2, the structure is similar to that of the illumination light source 1 of Example 1, and the mixing ratio of the wavelength conversion materials in the wavelength converter 12 is adjusted such that the color temperature of the composite light is equal to 7000 K and the DUV is equal to 0.

[0063] Fig.Figure 9 shows a spectral distribution of the compound light emitted by the illumination light source 1 of Example 2. In the spectral distribution of the compound light, the first peak wavelength is 450 nm, the second peak wavelength is 515 nm, and the third peak wavelength is 610 nm. The ratios Xa and Xb are 40% and 27%, respectively, the biological effect is 0.99, the PS is 88, and the average color rendering index Ra is 93. Example 3

[0064] In the case of the illumination light source 1 of Example 3, the structure is similar to that of the illumination light source 1 of Example 1, and the mixing ratio of the wavelength conversion materials in the wavelength converter 12 is adjusted such that the color temperature of the composite light is equal to 6000 K and the DUV is equal to 0.

[0065] Fig.Figure 10 shows a spectral distribution of the compound light emitted by the illumination light source 1 of Example 3. In the spectral distribution of the compound light, the first peak wavelength is 450 nm, the second peak wavelength is 515 nm, and the third peak wavelength is 610 nm. The ratios Xa and Xb are 43% and 35%, respectively, the biological effect is 0.89, the PS is 90, and the average color rendering index Ra is 94. Comparative example 1

[0066] The illumination light source of comparison example 1 is essentially identical to the illumination light source 1 of example 1, but differs from the illumination light source 1 of example 1 in that (Ca, Eu)8Mg(SiO4)4Cl2:Eu 2+ not included as a second wavelength conversion material. The illumination light source of comparison example 1 includes Y3AlsO.12 :Ce 3+ with a peak wavelength of 540 nm and (Sr, Ca)AlSiN3:Eu 2+ with a peak wavelength of 630 nm as the wavelength conversion material. In the illumination light source of comparison example 1, the mixing ratio of the wavelength conversion material is adjusted such that the color temperature of the composite light is 6500 K and the DUV is 0.

[0067] Fig. Figure 11 shows a spectral distribution of the compound light emitted by the illumination light source of comparison example 1. In the spectral distribution of the compound light, the first peak wavelength is 450 nm, the second peak wavelength is 515 nm, and the third peak wavelength is absent. The biological effect is 0.82, the PS is 49, and the average color rendering index Ra is 76. Comparative example 2

[0068] The illumination light source of comparison example 2 includes the blue LED with a peak wavelength of 450 nm and the green LED with a peak wavelength of 525 nm as a light-emitting solid element and contains only (Sr, Ca)AlSiN3:Eu 2+ with a peak wavelength of 630 nm as wavelength conversion material for the wavelength converter.

[0069] Fig. Figure 12 shows a spectral distribution of the compound light emitted by the illumination light source of comparison example 2. In the spectral distribution of the compound light, the first peak wavelength is 450 nm, the second peak wavelength is 525 nm, and the third peak wavelength is 630 nm. The ratios Xa and Xb are 85% and 80%, respectively, the biological effect is 0.88, the PS is 98, and the average color rendering index Ra is 74. Comparative example 3

[0070] The illumination light source of comparison example 3 is essentially identical to the illumination light source 1 of example 1. The illumination light source of comparison example 3 differs from the illumination light source 1 of example 1 in that the wavelength conversion material is not Y3AlsO. 12 :Ce 3+ The mixture includes the wavelength conversion materials, and the mixing ratio is adjusted such that the color temperature of the composite light is 6500 K and DUV is 0. Accordingly, the illumination light source of comparison example 3 includes (Ca, Eu)8Mg(SiO4)4Cl2:Eu. 2+ with a peak wavelength of 520 nm and (Sr, Ca)AlSiN3:Eu 2+ with a peak wavelength of 630 nm as a wavelength conversion material.

[0071] Fig.Figure 13 shows a spectral distribution of the compound light emitted by the illumination light source of comparison example 3. In the spectral distribution of the compound light, the first peak wavelength is 450 nm, the second peak wavelength is 510 nm, and the third peak wavelength is 625 nm. The ratios Xa and Xb are 72% and 68%, respectively, the biological effect is 0.95, the PS is 99, and the average color rendering index Ra is 74. Comparative example 4

[0072] The illumination source of comparison example 4 is essentially identical to illumination source 1 of example 1. The illumination source of comparison example 4 differs from illumination source 1 of example 1 in that Y3AlsO 12 :Ce 3+with a peak wavelength of 560 nm, it is used as a yellow fluorescent material. The illumination light source of comparison example 4 contains (Ca, Eu)8Mg(SiO4)4Cl2:Eu 2+ with a peak wavelength of 520 nm, Y3AlsO 12 :Ce 3+ with a peak wavelength of 560 nm and (Sr, Ca)AlSiN3:Eu 2+ with a peak wavelength of 630 nm as the wavelength conversion material. In the illumination light source of comparison example 4, the mixing ratio of the wavelength conversion material is adjusted such that the color temperature of the composite light is 6500 K and the DUV is 0.

[0073] Fig.Figure 14 shows a spectral distribution of the compound light emitted by the illumination light source of comparison example 4. In the spectral distribution of the compound light, the first peak wavelength is 450 nm, the second peak wavelength is 525 nm, and the third peak wavelength is 600 nm. The ratios Xa and Xb are 60% and 30%, respectively, the biological effect is 0.88, the PS is 71, and the average color rendering index Ra is 91. Comparative example 5

[0074] The light source in comparison example 5 is essentially identical to the light source 1 in example 1. The light source in comparison example 5 differs from the light source 1 in example 1 in that it uses BaSi2O2N2:Eu 2+with a peak wavelength of 550 nm, it is used as a yellow fluorescent material. The illumination light source of comparison example 5 contains BaSi2O2N2:Eu. 2+ with a peak wavelength of 500 nm, Y3AlsO 12 :Ce 3+ with a peak wavelength of 540 nm and (Sr, Ca)AlSiN3:Eu 2+ with a peak wavelength of 630 nm as the wavelength conversion material. In the light source module of comparison example 5, the mixing ratio of the wavelength conversion material is adjusted such that the color temperature of the composite light is 6500 K and the DUV is 0.

[0075] Fig.Figure 15 shows a spectral distribution of the compound light emitted by the illumination light source of comparison example 5. In the spectral distribution of the compound light, the first peak wavelength is 450 nm, the second peak wavelength is 500 nm, and the third peak wavelength is 610 nm. The ratios Xa and Xb are 2% and 45%, respectively, the biological effect is 0.96, the PS is 95, and the average color rendering index Ra is 93.

[0076] Table 1 shows key figures for examples 1 and 3 and comparison examples 1 to 5. [Table 1] correlated color temperature Duv ratioXa ratioXb biological effect Ra PS Example 1 6500 K 0 40% 35% 0,94 94 88 Example 2 7000 K 0 40% 27% 0,99 93 88 Example 3 6000 K 0 43% 35% 0,89 94 90 Comparative example 1 6500 K 0 0,82 76 49 Comparative example 2 6500 K 0 85% 80% 0,88 74 98 Comparative example 3 6500 K 0 72% 68% 0,95 74 99 Comparative example 4 6500 K 0 60% 30% 0,88 91 71 Comparative example 5 6500 K 0 2% 45% 0,96 83 95

[0077] As can be seen from Table 1, at a correlated color temperature of 5700 K to 7100 K, the illuminating light sources 1 of Examples 1 to 3 meet the conditions that the biological effect is greater than or equal to 0.85, the PS is greater than or equal to 80, and the average color rendering index Ra is greater than or equal to 90. With the illuminating light sources 1 of Examples 1 to 3, a pleasant and natural white light can be obtained in a living space if the correlated color temperature of the composite light is in the range of 5700 K to 7100 K. With the illuminating light sources 1 of Examples 1 to 3, if the biological effect of the composite light is greater than or equal to 0.85, the biological body is exposed to composite light during waking, thus facilitating a slight adjustment of the circadian rhythm.For the illumination light sources 1 of Examples 1 to 3, the optical freshness of the body irradiated with the composite light is enhanced when the average color rendering index Ra of the composite light is greater than or equal to 90. Accordingly, in a hospital, the light source units 1 and the light source module 30 are useful for diagnosing a patient. For the illumination light sources 1 of Examples 1 and 3, because the PS is greater than or equal to 80, the preferred skin color is perceptible in a patient irradiated with the composite light.

Claims

[1] Lighting light source (1), comprising: a light-emitting solid element (11); and a wavelength converter (12), wherein the wavelength converter (12) includes a wavelength conversion material which performs a wavelength conversion of a portion of the light emitted by the light-emitting solid element (11) and emits light of a different wavelength, the wavelength converter (12) emits a composite light consisting of the light emitted by the light-emitting solid element (11) and the light emitted by the wavelength conversion material, a correlated color temperature of the composite light lies in a range of 5700 K to 7100 K, a spectral distribution of the composite light exhibiting a first peak wavelength in a range of 430 nm to 470 nm, a second peak wavelength in a range of 490 nm to 540 nm, a third peak wavelength in a range of 600 nm to 640 nm, a first minimum value of intensity between the first peak wavelength and the second peak wavelength, and a second minimum value between the second peak wavelength and the third peak wavelength. a difference between the second peak value, which is of intensity in the second peak wavelength, and the first minimum value lies in a range of 30% to 55% with respect to the second peak value, a difference between the second peak and the second minimum value is in the range of 20% to 45% with respect to the second peak, the light-emitting solid element (11) is a blue light-emitting diode with a peak wavelength in the range of 430 nm to 470 nm, and The wavelength conversion material includes a blue-green fluorescent material with a peak wavelength in the range of 490 nm to 540 nm, a yellow fluorescent material with a peak wavelength in the range of 530 nm to 600 nm, and a red fluorescent material with a peak wavelength in the range of 600 nm to 670 nm. [2] Lighting light source (1) according to claim 1, wherein a half-width of an emission spectrum of the blue-green fluorescent material is in a range of 30 nm to 80 nm. [3] Illumination light source (1) according to claim 1 or 2, wherein the wavelength converter (12) consists of a mixture of the wavelength conversion material and a visible light transmitting translucent material and covers the light-emitting solid element (11) and the yellow fluorescent material and the red fluorescent material are arranged closer to the light-emitting solid element (11) than the blue-green fluorescent material. [4] Illumination light source (1) according to claim 1 or 2, wherein the wavelength converter (12) comprises a first wavelength converter (121) and a second wavelength converter (122), the first wavelength converter (121) consists of a mixture of the yellow fluorescent material, the red fluorescent material and a visible light transmitting first translucent material and covers the light-emitting solid element (11), and the second wavelength converter (122) consists of a mixture of a second translucent material transmitting visible light and the blue-green fluorescent material and covers the first wavelength converter (121). [5] Illumination light source (1) according to claim 4, wherein the second wavelength converter (122) covers the first wavelength converter (121) in a contact-free manner.

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