JP2021005696A - Light-emitting device and lighting unit - Google Patents

Abstract

To provide a light-emitting device and a lighting unit that can emit light that hardly gives discomfort to a human even though blue light is reduced.SOLUTION: A light-emitting device 10 emits illumination light specified in a light emission spectrum. The light emission spectrum has a first peak wavelength λ1 in a wavelength region of 360 nm to 415 nm, has a second peak wavelength λ2 in a wavelength region of 415 nm to 435 nm, and has a third peak wavelength λ3 in a wavelength region of 470 nm to 780 nm. The light emission spectrum has the minimum value of relative light intensity in a wavelength region of 450 nm to 470 nm.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a light emitting device and a lighting device.

A lighting device that cuts blue light is known (see, for example, Patent Document 1).

JP-A-2018-18982

The spectrum of light in which the component of blue light is simply reduced has a large difference from the spectrum of sunlight, which may give a sense of discomfort to humans.

An object of the present disclosure is to provide a light emitting device and a lighting device capable of emitting light that does not give a sense of discomfort to human beings although blue light is reduced.

The light emitting device according to the embodiment of the present disclosure emits illumination light specified by the light emission spectrum. The emission spectrum has a first peak wavelength in the wavelength region of 360 nm to 415 nm. The emission spectrum has a second peak wavelength in the wavelength region of 415 nm to 435 nm. The emission spectrum has a third peak wavelength in the wavelength region of 470 nm to 780 nm. The emission spectrum has a minimum value of relative light intensity in the wavelength region of 450 nm to 470 nm.

The lighting device according to the embodiment of the present disclosure includes at least one light emitting device and a control device for controlling the light emitting device. The control device emits illumination light specified in the emission spectrum to the at least one light emitting device. The emission spectrum has a first peak wavelength in the wavelength region of 360 nm to 415 nm. The emission spectrum has a second peak wavelength in the wavelength region of 415 nm to 435 nm. The emission spectrum has a third peak wavelength in the wavelength region of 470 nm to 780 nm. The emission spectrum has a minimum value of relative light intensity in the wavelength region of 450 nm to 470 nm.

The light emitting device and the lighting device according to the embodiment of the present disclosure can emit light that does not give a sense of discomfort to humans, although the blue light is reduced.

It is a block diagram which shows the structural example of the lighting apparatus which concerns on one Embodiment. It is a perspective view which shows the structural example of the lighting apparatus which includes a light emitting device. It is an external perspective view which shows the structural example of the light emitting device. FIG. 3 is a sectional view taken along the line AA of FIG. It is an enlarged view of the circled part of FIG. It is a graph which shows an example of the spectrum of the illumination light emitted by the illumination apparatus. It is a block diagram which shows the structural example of the lighting apparatus which concerns on other embodiment. It is a graph which shows an example of the sensitivity curve of the melatonin secreting cell.

Melatonin is secreted in the human body. Melatonin is a hormone that lowers human pulse, body temperature, blood pressure, and the like. The amount of melatonin secreted changes based on the circadian rhythm. Circadian rhythm is also called the biological clock. Melatonin is rarely secreted during the day and much at night. Humans feel drowsy due to the increased secretion of melatonin in the human body. Conversely, humans awaken by suppressing melatonin secretion in the human body.

Melatonin secretion is susceptible to light. When humans are exposed to light including blue light, melatonin secretion is suppressed. Humans are sensitive to light by photoreceptor cells. Photoreceptors include photoreceptor cells that secrete melatonin. Photoreceptor cells that secrete melatonin are also called melatonin-secreting cells. The melatonin-secreting cells sense the incident light with a predetermined sensitivity. As illustrated in FIG. 8, the sensitivity of light in melatonin-secreting cells has a wavelength characteristic. In FIG. 8, the horizontal axis and the vertical axis represent the wavelength of light and the relative sensitivity of each wavelength of the melatonin-secreting cell, respectively. The amount of light sensitivity in the melatonin-secreting cells is calculated as the product of the light intensity and the sensitivity for each wavelength of the incident light, and the product of each wavelength in the wavelength range included in the incident light. May be done. In melatonin-secreting cells, the greater the amount of light sensitivity, the more melatonin secretion is suppressed.

Humans often live in a 24-hour cycle that matches the movement of the sun. On the other hand, the circadian rhythm of human melatonin secretion has a cycle of about 25 hours. There is a difference of about 1 hour between the circadian rhythm of melatonin secretion and the human daily life cycle. When humans are exposed to sunlight containing blue light, the phase of the circadian rhythm of melatonin secretion is corrected to match the phase of the movement of the sun, that is, the phase of the human daily life cycle. As a result, even if there is a difference between the circadian rhythm of melatonin secretion and the daily life cycle of humans, humans are less likely to feel the effect of the difference.

When humans are exposed to light regardless of the movement of the sun, the phase of the circadian rhythm of melatonin secretion tends to shift with respect to the human daily life cycle. For example, when humans are exposed to light other than sunlight at night, the amount of melatonin secreted at night can be reduced. As a result, sleep disorders may be caused. When light other than sunlight enters the melatonin-secreting cells, it is required to reduce the amount of light sensed by the melatonin-secreting cells so that the light does not easily affect the amount of melatonin secreted. Specifically, it is required to reduce the wavelength component corresponding to the high relative sensitivity of the light incident on the melatonin-secreting cells. In the example of FIG. 8, the wavelength at which the relative sensitivity of the melatonin-secreting cells peaks is 464 nm. For example, light with reduced components in the wavelength region of 450 nm to 470 nm does not easily affect the amount of melatonin secreted by melatonin-secreting cells. In the present embodiment, light having a peak wavelength in the wavelength region of 450 nm to 470 nm is referred to as blue light. The wavelength region of 450 nm to 470 nm is referred to as a blue light region. Blue light is required to be reduced from the light that humans are exposed to so that the amount of human melatonin secreted is less affected.

On the other hand, the spectrum of light in which the component of blue light is simply reduced has a large difference from the spectrum of sunlight. For example, light with a reduced blue light component is easily recognized by humans as a color close to yellow. As a result, the light with the reduced blue light component can give a sense of discomfort to humans. It is required not only to reduce blue light but also to illuminate with light that does not give a sense of discomfort to humans.

(Embodiment)
As shown in FIG. 1, the lighting device 20 according to the embodiment includes a light emitting device 10 and a control device 22. The light emitting device 10 emits light that illuminates the illumination target 50. The light that illuminates the illumination target 50 is also referred to as illumination light. The illumination target 50 may include a predetermined space or a person or an object in the space. The control device 22 controls the light emitting device 10.

As will be described later, the light emitting device 10 emits light specified in a predetermined spectrum as illumination light. The predetermined spectrum may have a peak wavelength in the wavelength region of 360 nm to 415 nm and a peak wavelength in the wavelength region of 360 nm to 780 nm, for example. Light having a peak wavelength in the wavelength region of 360 nm to 415 nm is also referred to as purple light. The wavelength region of 360 nm to 415 nm is also referred to as a violet light region. Light having a peak wavelength in the wavelength region of 360 nm to 780 nm is also referred to as visible light. Visible light is assumed to include purple light. The wavelength region of 360 nm to 780 nm is also referred to as a visible light region. It is assumed that the visible light region includes a purple light region. The spectrum that identifies light is measured by spectroscopic methods using, for example, a spectrophotometer. In the present embodiment, the peak wavelength corresponds to the wavelength at which the relative light intensity becomes the maximum value in the graph of the spectrum. That is, the peak wavelength corresponds to the wavelength of the peak of the mountain located between the valley-shaped parts of the spectrum graph. However, the spectrum of light transformed by the phosphor to include various colors has tiny peaks and valleys. In the present embodiment, when the width from valley to valley is equal to or less than a predetermined value, the wavelength of the apex of the mountain located between these valleys is not regarded as the peak wavelength. The predetermined value may be set to, for example, 20 nm, or may be set to various other values. Further, the peak wavelength may be associated with the wavelength at which the relative light intensity becomes the maximum value in the spectrum obtained by smoothing the peaks and valleys having a width equal to or less than a predetermined value.

The control device 22 outputs a control instruction to each component of the lighting device 20 and acquires various information from each component. For example, the control device 22 controls the spectrum and intensity of the light emitted by the light emitting device 10 as illumination light. The light emitting device 10 can emit light specified in various spectra based on a control instruction from the control device 22. The control device 22 may be configured as a device separate from the lighting device 20.

The control device 22 may include at least one processor to provide control and processing power to perform various functions. The processor can execute a program that realizes various functions of the control device 22. The processor may be implemented as a single integrated circuit. The integrated circuit is also called an IC (Integrated Circuit). The processor may be implemented as a plurality of communicably connected integrated circuits and discrete circuits. The processor may be implemented on the basis of various other known techniques.

The control device 22 may include a storage unit. The storage unit may include an electromagnetic storage medium such as a magnetic disk, or may include a memory such as a semiconductor memory or a magnetic memory. The storage unit stores various information and programs executed by the control device 22. The storage unit may function as a work memory of the control device 22. At least a part of the storage unit may be configured as a separate body from the control device 22.

As shown in FIG. 2, the lighting device 20 may further include a housing 26. The housing 26 may hold the light emitting device 10. The light emitting device 10 may be arranged concentrically as illustrated in FIG. 2, but is not limited to this arrangement and may be arranged in various modes. The lighting device 20 may be configured as medical lighting. The lighting device 20 may be used to illuminate a part of the patient's body or the affected area. When the lighting device 20 is used as medical lighting, the human being as the lighting target 50 may include a patient or a medical worker such as a doctor or a nurse. The lighting device 20 may be configured as a shadowless lamp that does not easily form a shadow when illuminating the illumination target 50. When the lighting device 20 is configured as a surgical light, it may be used as surgical lighting for illuminating the operating room.

<Light emitting device>
As shown in FIGS. 3, 4 and 5, the light emitting device 10 includes a light emitting element 3 and a wavelength conversion member 6. The light emitting device 10 may further include an element substrate 2, a frame body 4, and a sealing member 5.

The light emitting element 3 emits light having a peak wavelength in a wavelength region of 360 nm to 415 nm, that is, a wavelength region of purple light. The wavelength conversion member 6 converts the light incident on the wavelength conversion member 6 from the light emitting element 3 into light having a peak wavelength in the visible light region, and emits the converted light. The light emitted by the light emitting element 3 excites the wavelength conversion member 6 to emit light of another wavelength. The light emitted by the light emitting element 3 is also referred to as excitation light.

The light emitting device 10 may have a plurality of wavelength conversion members 6. The plurality of wavelength conversion members 6 may emit light having different peak wavelengths. The light emitting device 10 can emit light having various spectra by controlling the intensity of the light emitted by each wavelength conversion member 6.

The element substrate 2 may be formed of, for example, a material having an insulating property. The element substrate 2 may be formed of, for example, a ceramic material such as alumina or mullite, a glass ceramic material, or a composite material obtained by mixing a plurality of these materials. The element substrate 2 may be formed of a polymer resin material or the like in which metal oxide fine particles whose thermal expansion can be adjusted are dispersed.

The element substrate 2 may include a wiring conductor that electrically conducts components such as a light emitting element 3 mounted on the element substrate 2 inside the main surface 2A of the element substrate 2 or the element substrate 2. The wiring conductor may be made of a conductive material such as tungsten, molybdenum, manganese, or copper. The wiring conductor is formed, for example, by printing a metal paste obtained by adding an organic solvent to tungsten powder on a ceramic green sheet to be an element substrate 2 in a predetermined pattern, laminating a plurality of ceramic green sheets, and firing them. May be done. A plating layer such as nickel or gold may be formed on the surface of the wiring conductor to prevent oxidation.

The element substrate 2 may be provided with a metal reflective layer at intervals from the wiring conductor and the plating layer in order to efficiently emit the light emitted by the light emitting element 3 to the outside. The metal reflective layer may be formed of, for example, a metal material such as aluminum, silver, gold, copper or platinum.

In this embodiment, the light emitting element 3 is an LED. An LED emits light to the outside by recombination of electrons and holes in a PN junction in which a P-type semiconductor and an N-type semiconductor are bonded. The light emitting element 3 is not limited to the LED, and may be a laser (LD) or another light emitting device.

The light emitting element 3 is mounted on the main surface 2A of the element substrate 2. The light emitting element 3 is electrically connected to the plating layer provided on the surface of the wiring conductor provided on the element substrate 2 via, for example, a brazing material or solder. The number of light emitting elements 3 mounted on the main surface 2A of the element substrate 2 is not particularly limited.

The light emitting element 3 may include a translucent substrate and an optical semiconductor layer formed on the translucent substrate. The translucent substrate includes a material capable of growing an opto-semiconductor layer on it by using, for example, a chemical vapor deposition method such as an organic metal vapor phase growth method or a molecular beam epitaxial growth method. The translucent substrate may be formed of, for example, sapphire, gallium nitride, aluminum nitride, zinc oxide, zinc selenide, silicon carbide, silicon (Si), zirconium dibodium or the like. The thickness of the translucent substrate may be, for example, 50 μm or more and 1000 μm or less.

The optical semiconductor layer may include a first semiconductor layer formed on a translucent substrate, a light emitting layer formed on the first semiconductor layer, and a second semiconductor layer formed on the light emitting layer. The first semiconductor layer, the light emitting layer, and the second semiconductor layer are, for example, a group III nitride semiconductor, a group III-V semiconductor such as gallium phosphorus or gallium arsenide, or a group III such as gallium nitride, aluminum nitride, or indium nitride. It may be formed of a nitride semiconductor or the like.

The thickness of the first semiconductor layer may be, for example, 1 μm or more and 5 μm or less. The thickness of the light emitting layer may be, for example, 25 nm or more and 150 nm or less. The thickness of the second semiconductor layer may be, for example, 50 nm or more and 600 nm or less.

The frame 4 may be formed of, for example, a ceramic material such as aluminum oxide, titanium oxide, zirconium oxide or yttrium oxide. The frame body 4 may be made of a porous material. The frame 4 may be formed of a resin material mixed with a powder containing a metal oxide such as aluminum oxide, titanium oxide, zirconium oxide or yttrium oxide. The frame body 4 is not limited to these materials, and may be formed of various materials.

The frame body 4 is connected to the main surface 2A of the element substrate 2 via, for example, resin, brazing material, solder, or the like. The frame body 4 is provided on the main surface 2A of the element substrate 2 so as to surround the light emitting element 3 at a distance from the light emitting element 3. The frame body 4 is provided so as to be inclined so that the inner wall surface expands outward as the distance from the main surface 2A of the element substrate 2 increases. The inner wall surface functions as a reflecting surface that reflects the light emitted by the light emitting element 3. The inner wall surface may include, for example, a metal layer formed of a metal material such as tungsten, molybdenum, or manganese, and a plating layer covering the metal layer and formed of a metal material such as nickel or gold. The plating layer reflects the light emitted by the light emitting element 3.

The shape of the inner wall surface of the frame body 4 may be circular in a plan view. Since the shape of the inner wall surface is circular, the frame body 4 can reflect the light emitted by the light emitting element 3 substantially uniformly toward the outside. The inclination angle of the inner wall surface of the frame body 4 may be set to, for example, an angle of 55 degrees or more and 70 degrees or less with respect to the main surface 2A of the element substrate 2.

The sealing member 5 is filled in the inner space surrounded by the element substrate 2 and the frame body 4, leaving a part of the upper part of the inner space surrounded by the frame body 4. The sealing member 5 seals the light emitting element 3 and transmits the light emitted by the light emitting element 3. The sealing member 5 may be made of, for example, a light-transmitting material. The sealing member 5 may be formed of, for example, a light-transmitting insulating resin material such as a silicone resin, an acrylic resin or an epoxy resin, or a light-transmitting glass material. The refractive index of the sealing member 5 may be set to, for example, 1.4 or more and 1.6 or less.

When the light emitting device 10 includes the sealing member 5, the purple light emitted from the light emitting element 3 passes through the sealing member 5 and is incident on the wavelength conversion member 6. As described above, the wavelength conversion member 6 converts the purple light incident from the light emitting element 3 into light having various peak wavelengths included in the visible light region. The light emitting element 3 is positioned so that the emitted purple light is incident on the wavelength conversion member 6. In other words, the wavelength conversion member 6 is positioned so that the light emitted from the light emitting element 3 is incident. In the configurations illustrated in FIGS. 3 to 5, the wavelength conversion member 6 is located along the upper surface of the sealing member 5 in a part of the upper part of the inner space surrounded by the element substrate 2 and the frame body 4. ing. Not limited to this example, for example, the wavelength conversion member 6 may be positioned so as to protrude from the upper part of the inner space surrounded by the element substrate 2 and the frame body 4.

As shown in FIG. 5, the wavelength conversion member 6 includes a translucent member having translucency, a first phosphor 61, a second phosphor 62, a third phosphor 63, a fourth phosphor, and a fifth fluorescence. You may have a body. The first phosphor 61, the second phosphor 62, the third phosphor 63, the fourth phosphor, and the fifth phosphor are also simply referred to as phosphors. It is assumed that the phosphor is contained inside the translucent member. The phosphor may be dispersed substantially uniformly inside the translucent member. The phosphor converts the purple light incident on the wavelength conversion member 6 into light having a peak wavelength included in the wavelength region of 360 nm to 780 nm, and emits the converted light.

The translucent member may be formed of, for example, a translucent insulating resin such as a fluororesin, a silicone resin, an acrylic resin or an epoxy resin, or a translucent glass material or the like.

The phosphor converts the incident purple light into light having various peak wavelengths.

The first phosphor 61 may convert violet light into light specified in a spectrum having a peak wavelength in, for example, a wavelength region of 400 nm to 500 nm, that is, blue light. The first phosphor 61 is, for example, BaMgAl ₁₀ O ₁₇ : Eu, or (Sr, Ca, Ba) ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu, (Sr, Ba) ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu. Etc. can be used.

The second phosphor 62 may convert violet light into light specified in the spectrum having a peak wavelength in the wavelength region of, for example, 450 nm to 550 nm, that is, blue-green light. As the second phosphor 62, for example, (Sr, Ba, Ca) ₅ (PO ₄ ) ₃ Cl: Eu, Sr ₄ Al ₁₄ O ₂₅ : Eu and the like can be used.

The third phosphor 63 may convert violet light into light specified in the spectrum having a peak wavelength in, for example, a wavelength region of 500 nm to 600 nm, that is, green light. The third phosphor 63 is, for example, SrSi ₂ (O, Cl) ₂ N ₂ : Eu, (Sr, Ba, Mg) ₂ SiO ₄ : Eu ²⁺ , or ZnS: Cu, Al, Zn ₂ SiO ₄ : Mn, etc. Can be used.

The fourth phosphor may convert violet light into light specified in the spectrum having a peak wavelength in the wavelength region of, for example, 600 nm to 700 nm, that is, red light. As the fourth phosphor, for example, Y ₂ O ₂ S: Eu, Y ₂ O ₃ : Eu, SrCaClAlSiN ₃ : Eu ²⁺ , CaAlSiN ₃ : Eu, CaAlSi (ON) ₃ : Eu, or the like can be used.

The fifth phosphor may convert violet light into light specified in the spectrum having a peak wavelength in the wavelength region of, for example, 680 nm to 800 nm, that is, near infrared light. Near-infrared light may include light in the wavelength region of 680 to 2500 nm. As the fifth phosphor, for example, 3Ga ₅ O ₁₂ : Cr or the like can be used.

The combination of types of phosphors contained in the wavelength conversion member 6 is not particularly limited. As shown in the region X of FIGS. 4 and 5, the wavelength conversion member 6 has a first phosphor 61, a second phosphor 62, a third phosphor 63, a fourth phosphor, and a fifth phosphor. You can. The wavelength conversion member 6 may have other types of phosphors. The wavelength conversion member 6 may contain each phosphor in various ratios.

The light emitting device 10 may include a plurality of wavelength conversion members 6. Each wavelength conversion member 6 may have a different combination of phosphors. The light emitting device 10 may include a light emitting element 3 that emits purple light to each wavelength conversion member 6. The light emitting device 10 can emit light having various spectra by controlling the intensity of purple light incident on each wavelength conversion member 6. In other words, the light emitting device 10 can emit light having various colors.

The lighting device 20 may have a plurality of light emitting devices 10. The plurality of light emitting devices 10 may include a first light emitting device and a second light emitting device. The control device 22 may independently control the intensity of the light emitted by the first light emitting device and the intensity of the light emitted by the second light emitting device, or may control them in association with each other. The spectrum of the light emitted by the first light emitting device may be different from the spectrum of the light emitted by the second light emitting device. The ratio of each phosphor contained in the wavelength conversion member 6 of the first light emitting device and the ratio of each phosphor contained in the wavelength conversion member 6 of the second light emitting device may be different. The control device 22 controls the intensity of the light emitted by the first light emitting device in association with the intensity of the light emitted by the second light emitting device so that the light emitted by the first light emitting device and the second light emitting device can be controlled. You may control the spectrum of the light combined with the emitted light. The light obtained by combining the light emitted by the first light emitting device and the light emitted by the second light emitting device is also referred to as synthetic light. The lighting device 20 may emit synthetic light as illumination light.

<Spectrum control of illumination light>
The control device 22 can control the spectrum of the illumination light as described above. The spectrum of illumination light is measured by spectroscopic methods using, for example, a spectrophotometer. The control device 22 may control the light emitting device 10 so that the spectrum of the illumination light is represented by the spectrum illustrated in FIG. In the graph of FIG. 6, the horizontal axis and the vertical axis represent the wavelength of the illumination light emitted by the illumination device 20, and the relative light intensity at each wavelength, respectively. In FIG. 6, the emission spectra SP1 and SP2 are shown by solid lines and broken lines, respectively.

The spectrum of the illumination light illustrated in FIG. 6 has a first peak wavelength λ1 in the wavelength region of 360 nm to 415 nm, a second peak wavelength λ2 in the wavelength region of 415 nm to 435 nm, and a wavelength of 470 nm to 780 nm. It has a third peak wavelength λ3 in the region. In FIG. 6, the third peak wavelength λ3 is about 630 nm, but may have other values. Light having a peak wavelength in the wavelength region of 415 nm to 435 nm is also referred to as indigo light. The wavelength region of 415 nm to 435 nm is also referred to as an indigo light region. The spectrum of illumination light illustrated in FIG. 6 further has a minimum value of relative light intensity in the wavelength region of 450 nm to 470 nm. The light emitting device 10 may emit illumination light specified by a spectrum having a peak wavelength in a purple light region and an indigo light region and having a minimum value of relative light intensity in a blue light region. The control device 22 may emit the illumination light specified in the above spectrum to the light emitting device 10.

Since the spectrum of the illumination light has a minimum value of the relative light intensity in the blue light region, the illumination light is less likely to affect the amount of melatonin secreted. Further, since the spectrum of the illumination light has a peak wavelength in the indigo light region, the difference in the spectrum between the illumination light and the sunlight can be reduced. Also, the color of the illumination light does not come too close to yellow when viewed from humans. As a result, the illumination light with reduced blue light is less likely to give a sense of discomfort to humans. Further, since the spectrum of the illumination light has a peak wavelength in the wavelength region of 470 nm to 780 nm, the spectrum of the illumination light becomes close to the spectrum of sunlight. As a result, the illumination light does not give a sense of discomfort to humans. The half width of the peak in the wavelength region of 470 nm to 780 nm may be larger than the half width of the peak in the wavelength region of 360 nm to 415 nm and the half width of the peak in the wavelength region of 415 nm to 435 nm. As a result, the illumination light can have a spectrum close to that of sunlight, and the illumination light is less likely to give a sense of discomfort to humans.

In the spectrum of illumination light, the minimum value of the relative light intensity in the wavelength region of 450 nm to 470 nm may be smaller than the relative light intensity in the first peak wavelength λ1. Further, the relative light intensity at the wavelength at which the relative sensitivity of the melatonin-secreting cells reaches the peak value may be smaller than the relative light intensity at the first peak wavelength λ1. By doing so, the illumination light is less likely to affect the secretion of melatonin.

In the spectrum of the illumination light, the relative light intensity of the wavelength at which the relative sensitivity of the melatonin-secreting cells reaches the peak value may be a predetermined ratio or less with respect to the relative light intensity at the second peak wavelength λ2 or the third peak wavelength λ3. .. The predetermined ratio may be, for example, 40% or 25%. The predetermined ratio is not limited to these values, and may be various values. By doing so, the illumination light is less likely to affect the secretion of melatonin.

In the spectrum of the illumination light, the relative light intensity at the second peak wavelength λ2 may be made larger than the relative light intensity at the first peak wavelength λ1. Further, when the relative light intensity at the first peak wavelength λ1 is 1, the relative light intensity at the second peak wavelength λ2 may be 1.5 or more. By doing so, the difference in spectrum between the illumination light and the sunlight can be reduced. Also, the color of the illumination light does not come too close to yellow when viewed from humans. As a result, it becomes difficult for humans to feel uncomfortable with the illumination light.

In the light emitting device 10 or the lighting device 20, the relative light intensity in the wavelength region of 500 nm to 650 nm of the illumination light spectrum is 15% or less different from the relative light intensity of the sunlight spectrum of the ASTM G173-03 standard. May be configured in. By doing so, it becomes difficult for humans to feel uncomfortable with the illumination light.

When the light emitting device 10 or the lighting device 20 is used as medical lighting, doctors and the like may be exposed to the illumination light at a high illuminance and are easily affected by the illumination light. By using the light emitting device 10 and the lighting device 20 according to the present embodiment as medical lighting, it is less likely to affect the secretion of melatonin in the body of a doctor or the like, and it is less likely to give a sense of discomfort to the doctor or the like.

As shown in FIG. 7, the illuminator 20 may further include a filter 24. The filter 24 may have a function of attenuating light in the wavelength region of 450 nm to 470 nm. That is, the filter 24 may reduce the relative light intensity in the wavelength region of 450 nm to 470 nm in the spectrum of light passing through the filter 24. The filter 24 may be composed of, for example, a resin containing a dye that absorbs light of a specific wavelength.

The filter 24 may be included in the light emitting device 10. When the light emitting device 10 includes the filter 24, the light in the wavelength region of 450 nm to 470 nm may be attenuated in the illumination light emitted by the light emitting device 10. By including the filter 24, the light emitting device 10 may emit the light specified by the spectrum illustrated in FIG. 6, regardless of whether or not it is incorporated in the lighting device 20. The light emitting device 10 may emit the light specified in the spectrum illustrated in FIG. 6 depending on the combination of phosphors, whether or not the filter 24 is provided. That is, the light emitting device 10 alone may emit illumination light specified by a spectrum having a peak wavelength in a purple light region and an indigo light region and a minimum value of relative light intensity in a blue light region. As a result, the illumination light emitted by the light emitting device 10 is less likely to affect the secretion of melatonin and is less likely to give a sense of discomfort to humans.

<Control of color temperature of illumination light>
The color of light is specified by the spectrum of the light and is also represented by the color temperature. Color temperature is a parameter associated with the temperature of the blackbody. The color temperature of the spectrum of light emitted by a blackbody having a temperature represented by T is represented by T. For example, the color temperature of the spectrum of light emitted by a 5000K (Kelvin) blackbody is represented as 5000K. The color of light having a color temperature of about 4000K to 5000K is also referred to as white. The lower the color temperature than white light, the more the color of the light can contain more red components. That is, light with a low color temperature looks reddish. The higher the color temperature than white light, the more the color of the light may contain a blue component. That is, light having a high color temperature looks bluish.

Not only the spectrum of the light emitted by the blackbody, but also the spectrum close to the spectrum of the light emitted by the blackbody may be represented by the color temperature. When a predetermined spectrum approximates the spectrum of light emitted by a blackbody having a temperature represented by T, the color temperature of the predetermined spectrum is represented by T. Whether or not the two light spectra are close to each other may be determined by various conditions. The condition for the two light spectra to be close to each other includes, for example, that the difference at each wavelength is within a predetermined range when the relative intensities of the two wavelengths are compared between the two light spectra. It's fine. The condition for the two light spectra to be close to each other may include, for example, that the difference in peak wavelength contained in each of the two light spectra is within a predetermined range. The conditions for the two light spectra to have an approximate relationship are not limited to these examples, and may include various conditions.

For example, the spectrum of sunlight around noon can be approximated to the spectrum of light emitted by a blackbody at about 5000K. In this case, the color temperature of sunlight around noon is expressed as about 5000K. The color of light represented by a color temperature of about 5000 K is also referred to as neutral white. The color of light represented by a color temperature of about 6500 K, which is higher than the color temperature of neutral white, is also called daylight color. The daylight color contains more blue light components than neutral white or components with shorter wavelengths than blue light, and looks bluish. On the contrary, neutral white looks closer to white than daylight color.

The light specified by the emission spectrum SP2 exemplified in FIG. 6 contains more indigo light than the light specified by the emission spectrum SP1. That is, it can be said that the color temperature of the light specified by the emission spectrum SP2 is higher than the color temperature of the light specified by the emission spectrum SP1. The control device 22 may control the color temperature of the illumination light by controlling the relative light intensity at the second peak wavelength λ2.

The control device 22 may determine the color temperature of the illumination light based on the operation by the user of the illumination device 20, or may determine the color temperature of the illumination light based on the information about the illumination target 50. The information regarding the illumination target 50 may include, for example, information regarding the color of the illumination target 50, or may include information indicating whether the illumination target 50 is a part of the human body. When the lighting device 20 is used as medical lighting, a doctor or the like can adjust the illumination light to a color temperature suitable for medical treatment.

(Comparison example)
The apparatus according to the comparative example emits illumination light including blue light and yellow light in which the blue light is converted by a phosphor. In the apparatus according to the comparative example, the greater the relative light intensity of the blue light contained in the illumination light, the greater the intensity of the entire illumination light including the relative light intensity of the light of other colors. That is, the apparatus according to the comparative example cannot independently control the relative light intensity of blue light and the intensity of the entire illumination light. Further, the apparatus according to the comparative example cannot independently control the relative light intensity of indigo light and the relative light intensity of blue light.

On the other hand, the lighting device 20 according to the present embodiment emits illumination light including light of various colors by exciting a phosphor with purple light. Therefore, the lighting device 20 according to the present embodiment can control the relative light intensity of the blue light of the lighting light independently of the intensity of the entire lighting light. By controlling the relative light intensity of the blue light of the illumination light independently of the intensity of the entire illumination light, only the relative light intensity of the blue light of the illumination light can be reduced. As a result, the lighting device 20 according to the present embodiment can reduce the influence of the lighting light on the secretion of melatonin. Further, the relative light intensity of indigo light among the illumination lights can be controlled independently of the relative light intensity of blue light. As a result, the lighting device 20 according to the present embodiment can emit illumination light that does not give a sense of discomfort to humans, although the blue light is reduced. In addition, the color temperature of the illumination light can be easily controlled.

The figure illustrating the embodiment according to the present disclosure is schematic. The dimensional ratios on the drawings do not always match the actual ones.

Although the embodiments according to the present disclosure have been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various modifications or modifications based on the present disclosure. It should be noted, therefore, that these modifications or modifications are within the scope of this disclosure. For example, the functions and the like included in each component and the like can be rearranged so as not to be logically inconsistent, and a plurality of components and the like can be combined or divided into one.

In the present disclosure, the descriptions such as "first" and "second" are identifiers for distinguishing the configuration. The configurations distinguished by the descriptions such as "first" and "second" in the present disclosure can exchange numbers in the configurations. For example, the first phosphor can exchange the identifiers "first" and "second" with the second phosphor. The exchange of identifiers takes place at the same time. Even after exchanging identifiers, the configuration is distinguished. The identifier may be deleted. The configuration with the identifier removed is distinguished by a code. Based solely on the description of identifiers such as "first" and "second" in the present disclosure, it shall not be used as a basis for interpreting the order of the configurations and for the existence of identifiers with smaller numbers.

10 Light emitting device (2: element substrate, 2A: main surface, 3: light emitting element, 4: frame body, 5: sealing member, 6: wavelength conversion member, 61 to 63: first to third phosphors)
20 Lighting device 22 Control device 24 Filter 26 Housing 50 Lighting target

Claims (10)

Illumination identified by an emission spectrum having a first peak wavelength in the wavelength region of 360 nm to 415 nm, a second peak wavelength in the wavelength region of 415 nm to 435 nm, and a third peak wavelength in the wavelength region of 470 nm to 780 nm. Emit light,
The emission spectrum is a light emitting device having a minimum value of relative light intensity in a wavelength region of 450 nm to 470 nm. The light emitting device according to claim 1, wherein the minimum value is smaller than the relative light intensity at the first peak wavelength. The light emitting device according to claim 1 or 2, wherein the relative light intensity at the second peak wavelength is larger than the relative light intensity at the first peak wavelength. The light emitting device according to claim 3, wherein the relative light intensity at the second peak wavelength is 1.5 or more when the relative light intensity at the first peak wavelength is 1. With at least one light emitting element that emits excitation light having the first peak wavelength,
A first phosphor that converts the excitation light into light having the second peak wavelength, and
The light emitting device according to any one of claims 1 to 4, further comprising a second phosphor that converts the excitation light into light having the third peak wavelength. It further has a plurality of wavelength conversion members having the first phosphor and the second phosphor.
The light emitting device according to claim 5, wherein the ratios of the first phosphor and the second phosphor in the plurality of wavelength conversion members are different from each other. With at least one light emitting device
A control device for controlling the light emitting device is provided.
The control device has an emission spectrum having a first peak wavelength in a wavelength region of 360 nm to 415 nm, a second peak wavelength in a wavelength region of 415 nm to 435 nm, and a third peak wavelength in a wavelength region of 470 nm to 780 nm. The illumination light specified in the above is emitted to at least one light emitting device.
An illumination device having an emission spectrum having a minimum value of relative light intensity in a wavelength region of 450 nm to 470 nm. The light emitting device includes a first light emitting device and a second light emitting device.
The lighting device according to claim 7, wherein the light obtained by synthesizing the light emitted by each of the first light emitting device and the second light emitting device is emitted as the illumination light. The first light emitting device and the second light emitting device each convert at least one light emitting element that emits excitation light having the first peak wavelength and the excitation light into light having the second peak wavelength. It has a first phosphor and a second phosphor that converts the excitation light into light having the third peak wavelength, and also
The ratio of the first phosphor and the second phosphor is different from that of the first light emitting device and the second light emitting device.
The lighting device according to claim 8, wherein the control device independently controls the relative light intensity of the first light emitting device and the relative light intensity of the second light emitting device. The lighting device according to any one of claims 7 to 9, which is used as a medical lighting.

Images