JP2024079073A - Lighting equipment - Google Patents

Abstract

To provide a lighting device with an excellent color rendering property.SOLUTION: A lighting device according to one embodiment of the present invention includes a first LED and a second LED having different continuous spectra in a range of at least 410nm or more to 700nm or less, the lighting device emitting a mixed light of the first LED and the second LED. The first LED includes a first maximum peak wavelength in a first wavelength range of 410nm or more to 470nm, and a second maximum peak wavelength in a second wavelength range of 610nm or more to 700nm or less. The second LED includes a third maximum peak wavelength in the first wavelength range, and a fourth maximum peak wavelength in the second wavelength range. A first minimum peak wavelength in which an emission intensity of the first LED is minimum in a wavelength range from the first maximum peak wavelength to the second maximum peak wavelength, is different from a second minimum peak wavelength in which an emission intensity of the second LED is minimum in a wavelength range from the third maximum peak wavelength to the fourth maximum peak wavelength.SELECTED DRAWING: Figure 4

Description

The present invention relates to a lighting device that uses LEDs (Light Emitting Diodes) and to a technology for emitting illumination light with excellent color rendering properties.

In recent years, LED lighting devices have been used as light sources due to their long life span and low power consumption. Some of these LED lighting devices generate white light with excellent color rendering properties. For example, Patent Document 1 describes a lamp that has two phosphors and a blue LED, and generates white light by emitting a mixed light of three light sources: the light emitted from the two phosphors and the light emitted from the LED.

JP 2002-60747 A

However, in Patent Document 1, there is variation in the emission intensity between the central wavelengths of the light emitted within the wavelength range of the emitted light, making it difficult to provide this lighting in places where lighting with excellent color rendering is required.

In view of the above, the object of the present invention is to provide a lighting device with excellent color rendering properties.

In order to achieve the above object, an illumination device according to one aspect of the present invention includes a first LED and a second LED having different continuous spectra at least in a wavelength range of 410 nm or more and 700 nm or less, and emits a mixed light of light emitted by the first LED and light emitted by the second LED,
The first LED has a first maximum peak wavelength that is a maximum peak in a first wavelength range of 410 nm to 470 nm, and a second maximum peak wavelength that is a maximum peak in a second wavelength range of 610 nm to 700 nm,
the second LED has a third maximum peak wavelength that has a maximum peak at a wavelength different from the first maximum peak wavelength in the first wavelength range, and a fourth maximum peak wavelength that has a maximum peak at a wavelength different from the second peak wavelength in the second wavelength range,
A first minimum peak wavelength at which the emission intensity of the first LED reaches its minimum peak in the wavelength range from the first maximum peak wavelength to the second maximum peak wavelength, and a second minimum peak wavelength at which the emission intensity of the second LED reaches its minimum peak in the wavelength range from the third maximum peak wavelength to the fourth maximum peak wavelength are different.

According to the above lighting device, the maximum peak wavelengths of the two LEDs are different in the first wavelength range and the second wavelength range, and the first minimum peak wavelength at which the emission intensity of the first LED is at its minimum peak in the wavelength range from the first maximum peak wavelength to the second maximum peak wavelength is different from the second minimum peak wavelength at which the emission intensity of the second LED is at its minimum peak in the wavelength range from the third maximum peak wavelength to the fourth maximum peak wavelength. In other words, since two LEDs with different wavelengths at which the emission intensity is at its minimum are used, they can compensate for each other's low emission intensity. This makes it possible to provide light with excellent color rendering properties with reduced unevenness in the entire emission spectrum.

In the spectrum of the mixed light, the maximum emission intensity in the first wavelength range may be 50% or more of the maximum emission intensity in the second wavelength range, and in the spectrum of the mixed light, the minimum emission intensity in the wavelength range from the fifth maximum peak wavelength, which is the maximum peak in the first wavelength range, to the sixth maximum peak wavelength, which is the maximum peak in the second wavelength range, may be 40% or more of the maximum emission intensity in the second wavelength range.

In the spectrum of the mixed light, the maximum emission intensity in the first wavelength range may be 70% or more of the maximum emission intensity in the second wavelength range, and in the spectrum of the mixed light, the minimum emission intensity in the wavelength range from the fifth maximum peak wavelength to the sixth maximum peak wavelength may be 50% or more of the maximum emission intensity in the second wavelength range.

The correlated color temperature of the first LED may be 5000K, the correlated color temperature of the second LED may be 3000K or more and 4000K or less, and the correlated color temperature of the mixed light may be 4000K or more and 5000K or less.

The first maximum peak wavelength may be in the range of 415 nm to 430 nm, the second maximum peak wavelength may be in the range of 610 nm to 660 nm, and the correlated color temperature of the first LED may be 5000K.

The third maximum peak wavelength may be in the range of 430 nm to 460 nm, the fourth maximum peak wavelength may be in the range of 630 nm to 680 nm, and the correlated color temperature of the second LED may be 4000K.

The average color rendering index Ra of the mixed light may be 90 or greater.

As described above, the present invention can provide a lighting device with excellent color rendering properties.

1 is a diagram showing a front view of an illumination device according to a first embodiment of the present invention. FIG. 2 is a diagram showing an emission spectrum of a first LED according to a first embodiment of the present invention. FIG. 4 is a diagram showing an emission spectrum of a second LED according to the first embodiment of the present invention. FIG. 2 is a diagram showing an emission spectrum of the lighting device according to the first embodiment of the present invention. FIG. 11 is a front view of an illumination device according to a second embodiment of the present invention. FIG. 11 is a diagram showing an emission spectrum of a third LED according to a second embodiment of the present invention. FIG. 11 is a diagram showing an emission spectrum of an illumination device according to a second embodiment of the present invention. FIG. 1 is a diagram showing a McCree curve.

The following describes an embodiment of the present invention with reference to the drawings.

First Embodiment
Fig. 1 is a diagram showing a front view of a lighting device 1 according to a first embodiment of the present invention. Fig. 2 is a diagram showing an emission spectrum of a first LED of the lighting device 1. Fig. 3 is a diagram showing a second emission spectrum of the lighting device 1. Fig. 4 is a diagram showing an emission spectrum of the lighting device 1. The lighting device 1 of the present invention is installed in a place where lighting with excellent color rendering properties is required. For example, it can be used in a museum where color reproducibility is required, an apparel shop where it is required that the color of clothes look the same indoors and outdoors, etc.

Here, color rendering is a numerical index that indicates the degree to which the color of an object illuminated by light is reproduced to be similar to that of sunlight, compared to when viewed under sunlight. Excellent color rendering (also called high color rendering) means that the color appearance is close to that when viewed under natural light (sunlight). Color rendering is determined by the JIS color rendering evaluation method, which is based on the evaluation method of the CIE (International Commission on Illumination), and is expressed using the average color rendering index (Ra). The average color rendering index has a maximum value of 100, and the closer to 100 the index is, the better the color rendering is evaluated to be.

The lighting device 1 has an overall shape of a straight tube fluorescent lamp, and emits light when inserted into a fluorescent lamp socket. The lighting device 1 has a case 10 and an LED board 20. In this embodiment, the lighting device 1 is described as a straight tube type, but of course it is not limited to this and may be a circular fluorescent lamp or a bulb-type fluorescent lamp, and may have a structure in which a light source and a power supply are housed in a housing, not limited to a lamp shape with a base.

The case 10 is a structure for housing the LED board 20. Its length is, for example, about 120 cm, which is the size of a typical fluorescent lamp. The case 10 is cylindrical and has a light diffusion section 11, an electrode 12, and a power source (not shown).

The light diffusion section 11 has a cylindrical structure that covers the LED board 20 and also serves to protect the LED board 20. It is made of a transparent or translucent material such as glass or a resin such as acrylic or polycarbonate, and diffuses the light from the LED board 20.

The electrode 12 is a terminal for supplying power from the outside to the LED board 20. It is inserted into a fluorescent light socket, and commercial power such as 100V is supplied from the socket to the inside of the case 10 via the electrode 12. It is not limited to this, and a DC power source may be connected from a power supply device to supply power to the inside of the case 10.

The power supply unit is disposed on the rear surface of the LED board 20 (the side opposite to the surface on which the first LED 30 and the second LED 31 are disposed) and rectifies an AC voltage of, for example, 100 V supplied from the outside and converts it into a DC voltage suitable for supply to the LED board 20 (not shown).

The LED board 20 has a first LED 30 and a second LED 40 arranged thereon. The LED board 20 is a rectangular board, and the length in the longitudinal direction is about 120 cm, which is close to the length of the case 10 of the lighting device 1. The width direction is several centimeters. On the LED board 20, the first LEDs 30 and the second LEDs 40, each about 3 mm square, are arranged alternately at equal intervals. In this embodiment, the first LEDs 30 and the second LEDs 40 are arranged at 10 mm intervals, but this is of course not limited to this. For example, two first LEDs 30 may be arranged at 10 mm intervals, and two second LEDs 40 may be arranged next to them at 10 mm intervals. Each LED is electrically connected to be conductive and emits light using the power generated by the power supply device.

As shown in FIG. 2, the first LED 30 has a continuous spectrum in at least a wavelength range of 410 nm to 700 nm, and includes a first light-emitting diode 30A and a first phosphor film 30B. In this embodiment, the first LED 30 emits white light with a correlated color temperature of 5000 K, but of course this is not limited thereto, and the correlated color temperature may be 4000 K or 6000 K. In this embodiment, the average color rendering index Ra of the first LED 30 is 95.

A DC voltage is applied to the first light-emitting diode 30A from the LED board 20. The first light-emitting diode 30A lights up and emits light in response to the applied DC voltage. The first light-emitting diode 30A emits light having a first maximum peak wavelength 31 in which the emission intensity is maximum (maximum peak position) in the wavelength range of 410 nm or more and 470 nm or less (wavelength range of blue light). A blue-emitting diode is used as the first light-emitting diode 30A.

The first phosphor film 30B is formed so as to cover the first light-emitting diode 30A. After the light of the first light-emitting diode 30A is absorbed by the first phosphor film 30B, it emits light having a second maximum peak wavelength 32 at which the emission intensity is maximum (at the maximum peak position) in the wavelength range of 610 nm or more and 700 nm or less (the wavelength range of red light).

In other words, the first phosphor film 30B is excited by the light from the first light-emitting diode 30A and emits light having a second maximum peak wavelength 32.

Light having the desired correlated color temperature (5000K in this embodiment) is emitted by combining the light emitted from the first light-emitting diode 30A and the light emitted from the first phosphor film.

In addition, in this embodiment, the first LED 30 is composed of a first light-emitting diode 30A and a first phosphor film 30B, but of course this is not limited to this, and light having the desired correlated color temperature may be emitted by multiple light-emitting diodes.

The emission spectrum of the first LED 30 will be described in detail. As shown in FIG. 2, the first LED has a continuous spectrum in the wavelength range of 410 nm to 750 nm. The vertical axis of FIG. 2 is the relative emission intensity (relative value), and the horizontal axis is the wavelength (nm). Here, emission intensity is the degree of brightness of light. Emission intensity is, for example, luminous intensity, which is the amount of luminous flux per unit solid angle. Below, the relationship between the vertical axis and the horizontal axis shown in the figures will be the same as in FIG. 2.

The first maximum peak wavelength 31 is more specifically in the wavelength range of 415 nm to 430 nm, and its center wavelength is approximately 420 nm. The second maximum peak wavelength 32 is more specifically in the wavelength range of 610 nm to 660 nm, and its center wavelength is approximately 620 nm.

The emission intensity of the second maximum peak wavelength 32 is approximately 0.7 (70%) compared to the emission intensity of the first maximum peak wavelength 31 (100%). The first minimum peak wavelength 33, where the emission intensity of the first LED 30 in the wavelength range from the first maximum peak wavelength 31 to the second maximum peak wavelength 32 is minimum (minimum peak position), is approximately 440 nm. The emission intensity of the first minimum peak wavelength 33 is approximately 0.38 (38%). The emission intensity in the wavelength range of 470 nm to 610 nm (between the first wavelength range and the second wavelength range, the yellow and green wavelength range) is approximately 0.6 (60%) to 0.7 (70%).

As shown in FIG. 3, the second LED 40 has a continuous spectrum in at least the wavelength range of 410 nm to 700 nm, and includes a second light-emitting diode 40A and a second phosphor film 40B. In this embodiment, the second LED 40 emits white light with a correlated color temperature of 4000 K, but of course this is not limited to this, and the correlated color temperature may be 3500 K or 4500 K. In this embodiment, the average color rendering index Ra of the second LED 40 is 95.

A DC voltage is applied to the second light-emitting diode 40A from the LED board 20. The second light-emitting diode 40A lights up and emits light in response to the applied DC voltage. The second light-emitting diode 40A emits light having a third maximum peak wavelength 41 where the emission intensity is maximum (maximum peak position) in the wavelength range of 410 nm or more and 470 nm or less (wavelength range of blue light). A blue-emitting diode is used as the second light-emitting diode 40A.

The second phosphor film 40B is formed so as to cover the second light-emitting diode 40A. After the light of the second light-emitting diode 40A is absorbed by the second phosphor film, it emits light having a fourth maximum peak wavelength 42 at which the emission intensity is maximum (at the maximum peak position) in the wavelength range of 610 nm or more and 700 nm or less (the wavelength range of red light).

That is, the second phosphor film 40B is excited by the light of the second light-emitting diode 40A and emits light having a fourth maximum peak wavelength 42.

Light having the desired correlated color temperature (4000K in this embodiment) is emitted by combining the light emitted from the second light-emitting diode 40A and the light emitted from the second phosphor film 40B.

In addition, in this embodiment, the second LED 40 is composed of a second light-emitting diode 40A and a second phosphor film 40B, but of course this is not limited to this, and light having the desired correlated color temperature may be emitted by multiple light-emitting diodes.

The emission spectrum of the second LED 40 will now be described in detail. As shown in FIG. 3, the second LED has a continuous spectrum in the wavelength range of 410 nm to 750 nm. The vertical axis of FIG. 3 is the relative emission intensity, and the horizontal axis is the wavelength (nm).

The third maximum peak wavelength 41 is more specifically in the wavelength range of 430 nm to 460 nm, and its center wavelength is approximately 445 nm. The fourth maximum peak wavelength 42 is more specifically in the wavelength range of 630 nm to 680 nm, and its center wavelength is approximately 660 nm.

The emission intensity of the third maximum peak wavelength 41 is 1 (100%), while the emission intensity of the fourth maximum peak wavelength 42 is approximately 1 (100%). The second minimum peak wavelength 43, where the emission intensity of the second LED 40 is minimum (minimum peak position) in the wavelength range from the third maximum peak wavelength 41 to the fourth maximum peak wavelength 42, is approximately 465 nm. The emission intensity of the second minimum peak wavelength 43 is approximately 0.3 (30%). The emission intensity in the wavelength range of 470 nm to 610 nm (yellow and green wavelength range between the first and second wavelength ranges) is approximately 0.3 (30%) to 0.8 (80%).

As shown in FIG. 4, the emission spectrum of the first mixed light 50 of the first LED 30 and the second LED 40 will be described. The first mixed light 50 has a continuous spectrum in the wavelength range of 410 nm to 750 nm. In this embodiment, the mixed light 50 emits white light with a correlated color temperature of 4500 K, but of course this is not limited to this, and by changing the output of the first LED 30 and the second LED 40, it is possible to change the correlated color temperature, for example, from 4000 K to 5000 K.

The first mixed light 50 emits light having a fifth maximum peak wavelength 51 in which the emission intensity is maximum (maximum peak position) in the wavelength range of 410 nm or more and 470 nm or less (wavelength range of blue light).

The first mixed light 50 also emits light having a sixth maximum peak wavelength 52 at which the emission intensity is maximum (the position at which the maximum peak occurs) in the wavelength range of 610 nm or more and 700 nm or less (the wavelength range of red light).

The fifth maximum peak wavelength 51 is more specifically in the wavelength range of 430 nm to 460 nm, and its center wavelength is approximately 445 nm. The sixth maximum peak wavelength 52 is more specifically in the wavelength range of 610 nm to 660 nm, and its center wavelength is approximately 620 nm.

The emission intensity of the fifth maximum peak wavelength 52 is approximately 0.78 (78%) compared to the emission intensity of 1 (100%) of the sixth maximum peak wavelength 52. The third minimum peak wavelength 53, where the emission intensity of the first mixed light 50 in the wavelength range from the fifth maximum peak wavelength 51 to the sixth maximum peak wavelength 52 is minimum (the position of the minimum peak), is approximately 465 nm. The emission intensity of the third minimum peak wavelength 53 is approximately 0.53 (53%). The emission intensity in the wavelength range of 470 nm to 610 nm (between the first wavelength range and the second wavelength range, the yellow and green wavelength range) is approximately 0.5 (50%) to 1 (100%).

The first peak wavelength 54 is in the wavelength range of 415 nm to 430 nm, and its central wavelength is approximately 420 nm. The emission intensity of the first peak wavelength 54 is approximately 0.4 (40%). The second peak wavelength 55 is in the wavelength range of 630 nm to 680 nm, and its central wavelength is approximately 660 nm. The second peak wavelength 55 is approximately 0.95 (95%). In this embodiment, the general color rendering index Ra of the first mixed light 50 is 98.

Here, the peak wavelength refers to a spectral portion that has a convex shape, separate from the fifth maximum peak wavelength 51, the sixth maximum peak wavelength 52, and the third minimum peak wavelength 53. The peak wavelength 54 is the light of the first light-emitting diode 30A, and the peak wavelength 55 is a portion of the light of the second phosphor film 40B excited by the light of the second light-emitting diode 40A.

Of the first mixed light 50, the fifth maximum peak wavelength 51 corresponds to the third maximum peak wavelength 41 of the second LED 40, and the sixth maximum peak wavelength 52 corresponds to the second maximum peak wavelength 32 of the first LED 30. Also, of the first mixed light 50, the third minimum peak wavelength 53 corresponds to the first minimum peak wavelength 43 of the second LED 40. Furthermore, the first peak wavelength 54 corresponds to the first maximum peak wavelength 41 of the first LED 40, and the second peak wavelength 55 corresponds to the second maximum peak wavelength 42 of the second LED 40.

The first LED 30 and the second LED 40 have different wavelengths, that is, the first maximum peak wavelength 31 and the third maximum peak wavelength 41, the second maximum peak wavelength 32 and the fourth maximum peak wavelength 42, and the first minimum peak wavelength 33 and the second minimum peak wavelength 43.

In other words, in the first mixed light 50 of the first LED 30 and the second LED 40, the first minimum peak wavelength 33 and the second minimum peak wavelength 43 are different in wavelength, so that the areas where the emission intensities are low do not overlap. This makes it possible to compensate for the areas where the emission intensities are low, and thus light with better color rendering can be emitted.

Specifically, the third minimum peak wavelength 53 of the first mixed light 50 corresponds to the second minimum peak wavelength 43 of the second LED 40, but the relative emission intensity is increased (from 0.3 to 0.53) compared to the second LED 40 alone.

In addition, since the first maximum peak wavelength 31 and the third maximum peak wavelength 41, and the second maximum peak wavelength 32 and the fourth maximum peak wavelength 42 are different, an emission spectrum with high emission intensity is generated over a wide wavelength range. This makes it possible to emit light with better color rendering than when the first LED 30 and the second LED 40 are used individually.

In addition to having excellent color rendering properties, the lighting device 1 of the present invention contains almost no infrared or ultraviolet components, so it can also be used to illuminate art exhibitions and storage rooms where paintings are stored.

It can also be used for lighting indoor plant cultivation. This is because the lighting device 1 of the present invention is close to the shape of the MacCree curve, which is a graph showing the average wavelength and photosynthetic efficiency of 22 types of plants (Figure 8). In other words, it can also be used for lighting in plant factories where plants are grown and in factories that manufacture products (plants) where the appearance of color is important.

Second Embodiment
Next, a second embodiment of the present invention will be described. Below, configurations different from the first embodiment will be mainly described, and configurations similar to those in the first embodiment will be given the same reference numerals, and descriptions thereof will be omitted or simplified.

Figure 5 is a diagram showing the front of the lighting device 1A according to the second embodiment, Figure 6 is a diagram showing the emission spectrum of the third LED 60 according to the second embodiment, and Figure 7 is a diagram showing the emission spectrum of the lighting device 1A according to the second embodiment.

The lighting device 1A has a configuration similar to that of the lighting device 1 of the first embodiment, except that the LED board 20A has a first LED 30 and a third LED 60.

As shown in FIG. 6, the third LED 60 has a continuous spectrum in the wavelength range of 410 nm to 750 nm, and includes a third light-emitting diode 60A and a third phosphor film 60B. In this embodiment, the third LED 60 emits white light with a correlated color temperature of 3000 K, but of course this is not limited to this, and the correlated color temperature may be 2500 K or 3500 K. In this embodiment, the average color rendering index Ra of the third LED 60 is 95.

A DC voltage is applied to the third light-emitting diode 60A from the LED board 20A. The first light-emitting diode 60A lights up and emits light in response to the applied DC voltage. The third light-emitting diode 60A emits light having a seventh maximum peak wavelength 61 where the emission intensity is at a maximum (maximum peak position) in the wavelength range of 410 nm to 470 nm (wavelength range of blue light). A blue-emitting diode is used as the third light-emitting diode 60A.

The third phosphor film 60B is formed so as to cover the third light emitting diode 60A. After the light 60A of the third light emitting diode is absorbed by the third phosphor film 60B, it emits light having an eighth maximum peak wavelength 62 at which the emission intensity is maximum (the position where the maximum peak occurs) in the wavelength range of 610 nm or more and 700 nm or less (the wavelength range of red light).

In other words, the third phosphor film 60B is excited by the light from the third light-emitting diode 60A and emits light having an eighth maximum peak wavelength 62.

Light having the desired correlated color temperature (3000K in this embodiment) is emitted by combining the light emitted from the third light-emitting diode 60A and the light emitted from the third phosphor film 60B.

In addition, in this embodiment, the third LED 60 is composed of a third light-emitting diode 60A and a third phosphor film 60B, but of course this is not limited to this, and light having the desired correlated color temperature may be emitted by multiple light-emitting diodes.

The emission spectrum of the third LED 60 will now be described in detail. As shown in FIG. 6, the third LED 60 has a continuous spectrum at least in the wavelength range of 410 nm to 700 nm. The vertical axis of FIG. 6 is the relative emission intensity, and the horizontal axis is the wavelength (nm).

The seventh maximum peak wavelength 61 is, more specifically, in the wavelength range of 430 nm to 460 nm, and its center wavelength is approximately 445 nm. The eighth maximum peak wavelength 62 is, more specifically, in the wavelength range of 630 nm to 680 nm, and its center wavelength is approximately 660 nm.

The emission intensity of the seventh maximum peak wavelength 61 is approximately 0.5 (50%), while the emission intensity of the eighth maximum peak wavelength 62 is 1 (100%). The fourth minimum peak wavelength 63, where the emission intensity of the third LED 60 is minimum (the position of the minimum peak) in the wavelength range from the seventh maximum peak wavelength 61 to the eighth maximum peak wavelength 62, is approximately 465 nm. The emission intensity of the fourth minimum peak wavelength 63 is approximately 0.1 (10%). The emission intensity in the wavelength range of 470 nm to 610 nm (between the first wavelength range and the second wavelength range, the yellow and green wavelength range) is approximately 0.1 (10%) to 0.8 (80%).

As shown in FIG. 7, the emission spectrum of the second mixed light 70 of the first LED 30 and the third LED 60 will be described. The second mixed light 70 has a continuous spectrum in the wavelength range of 410 nm to 750 nm. In this embodiment, the second mixed light 70 emits white light with a correlated color temperature of 4000 K, but of course this is not limited to this, and by changing the output of the first LED 30 and the third LED 60, it is possible to change the correlated color temperature, for example, from 3000 K to 5000 K.

The second mixed light 70 emits light having a ninth maximum peak wavelength 71 at which the emission intensity is maximum (the position at which the maximum peak occurs) in the wavelength range of 410 nm or more and 470 nm or less (the wavelength range of blue light).

The second mixed light 70 also emits light having a tenth maximum peak wavelength 72 at which the emission intensity is maximum (the position at which the maximum peak occurs) in the wavelength range of 610 nm or more and 700 nm or less (the wavelength range of red light).

The ninth maximum peak wavelength 71 is, more specifically, in the wavelength range of 430 nm to 460 nm, and its central wavelength is approximately 445 nm. The tenth maximum peak wavelength 72 is, more specifically, in the wavelength range of 610 nm to 660 nm, and its central wavelength is approximately 620 nm.

The emission intensity of the ninth maximum peak wavelength 71 is approximately 0.52 (52%) compared to the emission intensity of the tenth maximum peak wavelength 72 being 1 (100%). The fifth minimum peak wavelength 73, where the emission intensity of the second mixed light 70 in the wavelength range from the ninth maximum peak wavelength 71 to the tenth maximum peak wavelength 72 is minimum (the position where the minimum peak occurs), is approximately 465 nm. The emission intensity of the fifth minimum peak wavelength 73 is approximately 0.4 (40%). The emission intensity in the wavelength range of 470 nm to 610 nm (between the first wavelength range and the second wavelength range, the yellow and green wavelength range) is approximately 0.4 (40%) to 0.95 (95%).

The third peak wavelength 74 is in the wavelength range of 415 nm to 430 nm, and its central wavelength is approximately 420 nm. The emission intensity of the third peak wavelength 74 is approximately 0.4 (40%). The fourth peak wavelength 75 is in the wavelength range of 630 nm to 680 nm, and its central wavelength is approximately 660 nm. The fourth peak wavelength 75 is approximately 0.95 (95%). In this embodiment, the general color rendering index Ra of the second mixed light 70 is 98.

Here, the peak wavelength refers to a convex spectral portion different from the ninth maximum peak wavelength 71, the tenth maximum peak wavelength 72, and the fifth minimum peak wavelength 73, as described above. The peak wavelength 74 is the light of the first light-emitting diode 30A, and the peak wavelength 75 is a portion of the light of the third phosphor film 60B excited by the light of the third light-emitting diode 60A.

Of the second mixed light 70, the ninth maximum peak wavelength 71 corresponds to the seventh maximum peak wavelength 61 of the third LED 60, and the tenth maximum peak wavelength 72 corresponds to the second maximum peak wavelength 32 of the first LED 30. Also, of the second mixed light 70, the fifth minimum peak wavelength 73 corresponds to the fourth minimum peak wavelength 63 of the third LED 60. Furthermore, the third peak wavelength 74 corresponds to the first maximum peak wavelength 41 of the first LED 40, and the fourth peak wavelength 75 corresponds to the eighth maximum peak wavelength 62 of the third LED 60.

The first LED 30 and the third LED 60 have different wavelengths for the first maximum peak wavelength 31 and the seventh maximum peak wavelength 61, the second maximum peak wavelength 32 and the eighth maximum peak wavelength 62, and the first minimum peak wavelength 33 and the fourth minimum peak wavelength 63.

In other words, in the second mixed light 70 of the first LED 30 and the third LED 60, the first minimum peak wavelength 33 and the fourth minimum peak wavelength 63 are different in wavelength, so that the areas where the emission intensities are low do not overlap. This makes it possible to compensate for the areas where the emission intensities are low, and thus light with better color rendering can be emitted.

Specifically, the fifth minimum peak wavelength 73 of the second mixed light 70 corresponds to the fourth minimum peak wavelength 63 of the third LED 60, but the relative emission intensity is increased (0.1 to 0.4) compared to the third LED 60 alone.

In addition, since the first maximum peak wavelength 31 and the seventh maximum peak wavelength 61, and the second maximum peak wavelength 32 and the eighth maximum peak wavelength 62 are different, an emission spectrum with high emission intensity is generated over a wide wavelength range. This makes it possible to emit light with better color rendering than when the first LED 30 and the third LED 60 are used individually.

The above describes an embodiment of the present invention, but the present invention is not limited to the above embodiment, and various modifications (e.g., changing the correlated color temperature of the combined LEDs) can of course be made.

Reference Signs List 1: Illumination device 10: Case 11: Light diffusion portion 12: Electrode 20: LED substrate 30: First LED
31: First maximum peak wavelength; 32: Second maximum peak wavelength; 33: First minimum peak wavelength; 40: Second LED
41: third maximum peak wavelength 42: fourth maximum peak wavelength 43: second minimum peak wavelength 50: first mixed light 51: fifth maximum peak wavelength 52: sixth maximum peak wavelength 53: third minimum peak wavelength 60: third LED
70...Second mixed light

Claims (7)

A lighting device comprising a first LED and a second LED having different continuous spectra at least in a wavelength range of 410 nm to 700 nm, and emitting a mixed light of light emitted by the first LED and light emitted by the second LED,
the first LED has a first maximum peak wavelength that is a maximum peak in a first wavelength range of 410 nm to 470 nm and a second maximum peak wavelength that is a maximum peak in a second wavelength range of 610 nm to 700 nm,
the second LED has a third maximum peak wavelength that is a maximum peak at a wavelength different from the first maximum peak wavelength in the first wavelength range, and a fourth maximum peak wavelength that is a maximum peak at a wavelength different from the second peak wavelength in the second wavelength range,
a first minimum peak wavelength at which the emission intensity of the first LED reaches a minimum peak in the wavelength range from the first maximum peak wavelength to the second maximum peak wavelength, and a second minimum peak wavelength at which the emission intensity of the second LED reaches a minimum peak in the wavelength range from the third maximum peak wavelength to the fourth maximum peak wavelength, which are different from each other. 2. The lighting device according to claim 1,
In the spectrum of the mixed light, a maximum emission intensity in the first wavelength range is 50% or more of a maximum emission intensity in the second wavelength range,
in the spectrum of the mixed light, a minimum emission intensity in a wavelength range from a fifth maximum peak wavelength which is a maximum peak in the first wavelength range to a sixth maximum peak wavelength which is a maximum peak in the second wavelength range is 40% or more of a maximum emission intensity in the second wavelength range. 2. The lighting device according to claim 1,
In the spectrum of the mixed light, a maximum emission intensity in the first wavelength range is 70% or more of a maximum emission intensity in the second wavelength range,
a minimum emission intensity in a wavelength range from the fifth maximum peak wavelength to the sixth maximum peak wavelength in the spectrum of the mixed light is 50% or more of a maximum emission intensity in the second wavelength range. 2. The lighting device according to claim 1,
The correlated color temperature of the first LED is 5000K;
The correlated color temperature of the second LED is equal to or greater than 3000 K and equal to or less than 4000 K,
The mixed light has a correlated color temperature of 4000K or more and 5000K or less. 2. The lighting device according to claim 1,
the first maximum peak wavelength is in the range of 415 nm to 430 nm,
the second maximum peak wavelength is in the range of 610 nm to 660 nm,
The lighting device comprises: a first LED having a correlated color temperature of 5000K. 2. The lighting device according to claim 1,
the third maximum peak wavelength is in the range of 430 nm to 460 nm,
the fourth maximum peak wavelength is in the range of 630 nm to 680 nm,
The second LED has a correlated color temperature of 4000K. 2. The lighting device according to claim 1,
The mixed light has an average color rendering index Ra of 90 or more.

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