Lighting device

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

Technical Field

[0001] The present invention relates to a lighting device using an LED (Light Emitting Diode), and relates to a technique for emitting illumination light with excellent color rendering properties.

Background Art

[0002] In recent years, LED lighting devices have been used as light sources due to their long service life 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 emits mixed light of three light sources, namely the light emitted from the two phosphors and the light emitted from the LED, to generate white light.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in Patent Document 1, there is unevenness in the emission intensity between the central wavelengths of the respective emitted lights within the wavelength range of the emitted light, so it has been difficult to provide the illumination in places where illumination with excellent color rendering properties is required.

[0005] In view of the circumstances described above, an object of the present invention is to provide a lighting device with excellent color rendering properties.

Means for Solving the Problems

[0006] To achieve the above objective, an illumination device according to one embodiment of the present invention has a first LED and a second LED having different continuous spectra in a wavelength range of at least 410 nm to 700 nm, and emits a mixed light of light emitted from the first LED and the second LED, The first LED described above has a first maximum peak wavelength that occurs in a first wavelength range of 410 nm to 470 nm, and a second maximum peak wavelength that occurs in a second wavelength range of 610 nm to 700 nm. The second LED has a third maximum peak wavelength that is at a different wavelength from the first maximum peak wavelength in the first wavelength range, and a fourth maximum peak wavelength that is at a different wavelength from the second peak wavelength in the second wavelength range. In the wavelength range from the first maximum peak wavelength to the second maximum peak wavelength, the first minimum peak wavelength at which the emission intensity of the first LED is at its minimum peak 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.

[0007] According to the above lighting device, the maximum peak wavelengths of the two LEDs differ in the first wavelength range and the second wavelength range. In the wavelength range from the first to the second maximum peak wavelength, the first minimum peak wavelength at which the emission intensity of the first LED is at its lowest peak differs, and in the wavelength range from the third to the fourth maximum peak wavelength, the second minimum peak wavelength at which the emission intensity of the second LED is at its lowest peak differs. In other words, because two LEDs with different wavelengths at which their emission intensity is at its lowest are used, they can compensate for each other's low emission intensity regions. As a result, unevenness in the overall emission spectrum is suppressed, and light with excellent color rendering can be provided.

[0008] In the spectrum of the mixed light described above, the maximum emission intensity in the first wavelength range is 50% or more of the maximum emission intensity in the second wavelength range, and in the spectrum of the mixed light described above, 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.

[0009] In the spectrum of the mixed light described above, the maximum emission intensity in the first wavelength range is 70% or more of the maximum emission intensity in the second wavelength range, and in the spectrum of the mixed light described above, 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.

[0010] The correlated color temperature of the first LED is 5000K, the correlated color temperature of the second LED is 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.

[0011] 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, and the correlated color temperature of the first LED may be 5000 K.

[0012] 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, and the correlated color temperature of the second LED may be 4000 K.

[0013] The average color rendering index Ra of the above mixed light may be 90 or higher. [Effects of the Invention]

[0014] As described above, the present invention provides a lighting device with excellent color rendering properties.

Brief Description of the Drawings

[0015] [Figure 1] This is a diagram showing the front face of the lighting device according to the first embodiment of the present invention. [Figure 2] This is a diagram showing the emission spectrum of the first LED according to the first embodiment of the present invention. [Figure 3] This is a diagram showing the emission spectrum of the second LED according to the first embodiment of the present invention. [Figure 4] This is a diagram showing the emission spectrum of the lighting device according to the first embodiment of the present invention. [Figure 5] This is a diagram showing the front face of the lighting device according to the second embodiment of the present invention. [Figure 6] This is a diagram showing the emission spectrum of the third LED according to the second embodiment of the present invention. [Figure 7] This is a diagram showing the emission spectrum of the lighting device according to the second embodiment of the present invention. [Figure 8] This is a diagram showing the MacAdam curve.

Modes for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0017] <First Embodiment> Figure 1 is a diagram showing the front face of the lighting device 1 according to the first embodiment of the present invention. Figure 2 is a diagram showing the emission spectrum of the first LED of the lighting device 1. Figure 3 is a diagram showing the second emission spectrum of the lighting device 1. Figure 3 is a diagram showing the emission spectrum of the lighting device 1. The lighting device 1 of the present invention is installed in places where lighting with excellent color rendering properties is required. Examples include museums where color reproducibility is required, and apparel shops where the color appearance of clothing is required to be the same indoors and outdoors.

[0018] Here, the color rendering property is an index expressed by a numerical value that indicates how close the light can reproduce light similar to sunlight, in comparison with the color tone of an object illuminated by light when viewed under sunlight. Excellent color rendering property (also referred to as high color rendering property) means that the appearance of colors is close to that when viewed under natural light (sunlight). Here, the color rendering property is determined by the JIS color rendering evaluation method based on the evaluation method of the CIE (International Commission on Illumination), and is expressed using the general color rendering index (Ra). The maximum value of the general color rendering index is 100, and the closer the value is to 100, the more excellent the color rendering property is evaluated to be.

[0019] The lighting device 1 has a shape of a straight-tube fluorescent lamp as a whole, and emits light by being inserted into a socket for a fluorescent lamp. The lighting device 1 includes a case 10 and an LED substrate 20. In the present embodiment, the lighting device 1 is described as a straight-tube type, but is of course not limited thereto, and may be a circular fluorescent lamp or a bulb-type fluorescent lamp. The lighting device is not limited to a lamp shape provided with a base, and may have a structure in which a light source and a power supply device are housed in a housing.

[0020] The case 10 has a structure for accommodating the LED substrate 20. The length is, for example, about 120 cm, which is the size of a general fluorescent lamp. The case 10 has a cylindrical shape, and includes a light diffusion portion 11, electrodes 12, and a power supply (not shown).

[0021] The light diffusion portion 11 has a structure that covers the LED substrate 20 in a cylindrical shape, and also has a role of protecting the LED substrate 20. The material is, for example, transparent or translucent made of resin such as glass, acrylic, or polycarbonate, and diffuses light from the LED substrate 20.

[0022] The electrodes 12 are terminals for supplying electric power to the LED substrate 20 from the outside. The electrodes are inserted into the socket of the fluorescent lamp, and commercial power of 100V or the like is supplied from the socket into the case 10 via the electrodes 12. The present invention is not limited to this, and a DC power supply may be connected from a power supply device to supply power into the case 10.

[0023] The power supply unit is located on the back side of the LED board 20 (opposite the side on which the first LED 30 and the second LED 31 are placed), and rectifies an AC voltage such as 100V supplied from an external source, converting it into a DC voltage suitable for supplying to the LED board 20 (not shown).

[0024] The LED substrate 20 has a first LED 30 and a second LED 40 arranged on it. The LED substrate 20 is a rectangular substrate, and its length in the longitudinal direction is about 120 cm, which is close to the length of the case 10 of the lighting device 1. Its width is several centimeters. On the LED substrate 20, the first LED 30 and the second LED 40, which are approximately 3 mm square, are arranged alternately at equal intervals. In this embodiment, the first LED 30 and the second LED 40 are arranged at 10 mm intervals, but of course, it is 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 connected to conduct electricity and emits light using power generated by the power supply.

[0025] As shown in Figure 2, the first LED 30 has a continuous spectrum in a wavelength range of at least 410 nm to 700 nm and comprises 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 is not limited to this, and may have a correlated color temperature of 4000 K or 6000 K. In this embodiment, the average color rendering index Ra of the first LED 30 is 95.

[0026] A DC voltage is applied to the first light-emitting diode 30A from the LED substrate 20. The first light-emitting diode 30A lights up and emits light in accordance with the applied DC voltage. The first light-emitting diode 30A emits light having a first maximum peak wavelength 31, which is the position of maximum peak (maximum peak) in the wavelength range of 410 nm to 470 nm (the wavelength range of blue light). A blue light-emitting diode is used as the first light-emitting diode 30A.

[0027] The first phosphor film 30B is formed so as to cover the first light-emitting diode 30A. The light from the first light-emitting diode 30A is absorbed by the first phosphor film 30B and then emits light having a second maximum peak wavelength 32, which is the position of maximum peak emission intensity in the wavelength range of 610 nm to 700 nm (the wavelength range of red light).

[0028] 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.

[0029] Light is emitted from the first light-emitting diode 30A and the first phosphor film, resulting in the emission of light having a desired correlated color temperature (5000K in this embodiment).

[0030] 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, it is not limited to this, and light with a desired correlated color temperature may be emitted by multiple light-emitting diodes.

[0031] The emission spectrum of the first LED 30 will now be described in detail. As shown in Figure 2, the first LED has a continuous spectrum in the wavelength range of 410 nm to 750 nm. In Figure 2, the vertical axis represents relative emission intensity (relative value), and the horizontal axis represents 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. The relationship between the vertical and horizontal axes in the following figures will be the same as in Figure 2.

[0032] The first maximum peak wavelength 31 is more specifically in the wavelength range of 415 nm to 430 nm, with a central wavelength of approximately 420 nm. The second maximum peak wavelength 32 is more specifically in the wavelength range of 610 nm to 660 nm, with a central wavelength of approximately 620 nm.

[0033] The emission intensity at the second maximum peak wavelength 32 is approximately 0.7 (70%) compared to the first maximum peak wavelength 31, which has an emission intensity of 1 (100%). Furthermore, the first minimum peak wavelength 33, which is the minimum peak position (minimum peak position) where the emission intensity of the first LED 30 is minimum in the wavelength range from the first maximum peak wavelength 31 to the second maximum peak wavelength 32, is approximately 440 nm. The emission intensity at the first minimum peak wavelength 33 is approximately 0.38 (38%). In addition, the emission intensity in the wavelength range from 470 nm to 610 nm (between the first and second wavelength ranges, representing the yellow and green wavelength ranges) is approximately between 0.6 (60%) and 0.7 (70%).

[0034] Next, as shown in Figure 3, the second LED 40 has a continuous spectrum in a wavelength range of at least 410 nm to 700 nm and comprises 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 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.

[0035] A DC voltage is applied to the second light-emitting diode 40A from the LED substrate 20. The second light-emitting diode 40A lights up and emits light in accordance with the applied DC voltage. The second light-emitting diode 40A emits light having a third maximum peak wavelength 41, which is the position of maximum peak, with maximum emission intensity in the wavelength range of 410 nm to 470 nm (the wavelength range of blue light). A blue light-emitting diode is used as the second light-emitting diode 40A.

[0036] The second phosphor film 40B is formed so as to cover the second light-emitting diode 40A. After the light from the second light-emitting diode 40A is absorbed by the second phosphor film, it emits light having a fourth maximum peak wavelength 42, which is the position where the emission intensity is maximized (maximum peak position) in the wavelength range of 610 nm to 700 nm (the wavelength range of red light).

[0037] In other words, the second phosphor film 40B is excited by the light from the second light-emitting diode 40A and emits light having a fourth maximum peak wavelength 42.

[0038] Light is emitted from the second light-emitting diode 40A and the second phosphor film 40B, resulting in the emission of light having a desired correlated color temperature (4000K in this embodiment).

[0039] 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, it is not limited to this, and light with a desired correlated color temperature may be emitted by multiple light-emitting diodes.

[0040] The emission spectrum of the second LED 40 will now be described in detail. As shown in Figure 3, the second LED has a continuous spectrum in the wavelength range from 410 nm to 750 nm. In Figure 3, the vertical axis represents relative emission intensity, and the horizontal axis represents wavelength (nm).

[0041] The third maximum peak wavelength 41 is more specifically in the wavelength range of 430 nm to 460 nm, with its center wavelength being approximately 445 nm. The fourth maximum peak wavelength 42 is more specifically in the wavelength range of 630 nm to 680 nm, with its center wavelength being approximately 660 nm.

[0042] The emission intensity at the fourth maximum peak wavelength 42 is approximately 1 (100%), compared to the emission intensity of 1 (100%) at the third maximum peak wavelength 41. Furthermore, the second minimum peak wavelength 43, where the emission intensity of the second LED 40 is minimized (the minimum peak position) within the wavelength range from the third maximum peak wavelength 41 to the fourth maximum peak wavelength 42, is approximately 465 nm. The emission intensity at the second minimum peak wavelength 43 is approximately 0.3 (30%). Additionally, the emission intensity in the wavelength range from 470 nm to 610 nm (between the first and second wavelength ranges, representing the yellow and green wavelength ranges) is approximately between 0.3 (30%) and 0.8 (80%).

[0043] As shown in Figure 4, the emission spectrum of the first mixed light 50 from 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 it 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 from 4000 K to 5000 K, for example.

[0044] The first mixed light 50 emits light having a fifth maximum peak wavelength 51, which has the maximum emission intensity (maximum peak position) in the wavelength range of 410 nm to 470 nm (the wavelength range of blue light).

[0045] Furthermore, the first mixed light 50 emits light having a sixth maximum peak wavelength 52, which has the maximum emission intensity (position of maximum peak) in the wavelength range of 610 nm to 700 nm (the wavelength range of red light).

[0046] The fifth maximum peak wavelength 51 is more specifically in the wavelength range of 430 nm to 460 nm, with a central wavelength of approximately 445 nm. The sixth maximum peak wavelength 52 is more specifically in the wavelength range of 610 nm to 660 nm, with a central wavelength of approximately 620 nm.

[0047] The emission intensity at the 5th maximum peak wavelength 52 is approximately 0.78 (78%) compared to the emission intensity of 1 (100%) at the 6th maximum peak wavelength 52. Furthermore, the 3rd minimum peak wavelength 53, which is the position where the emission intensity of the 1st mixed light 50 is minimized (the position of the minimum peak) in the wavelength range from the 5th maximum peak wavelength 51 to the 6th maximum peak wavelength 52, is approximately 465 nm. The emission intensity at the 3rd minimum peak wavelength 53 is approximately 0.53 (53%). In addition, the emission intensity in the wavelength range from 470 nm to 610 nm (between the 1st and 2nd wavelength ranges, the yellow and green wavelength ranges) is approximately between 0.5 (50%) and 1 (100%).

[0048] Furthermore, the first peak wavelength 54 is in the wavelength range of 415 nm to 430 nm, with its center wavelength being 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, with its center wavelength being approximately 660 nm. The emission intensity of the second peak wavelength 55 is approximately 0.95 (95%). In this embodiment, the average color rendering index Ra of the first mixed light 50 is 98.

[0049] Here, the peak wavelength refers to a convex spectral portion, distinct from the fifth maximum peak wavelength 51, the sixth maximum peak wavelength 52, and the third minimum peak wavelength 53. Peak wavelength 54 is the light from the first light-emitting diode 30A, and peak wavelength 55 is a portion of the light excited by the second phosphor film 40B by the light from the second light-emitting diode 40A.

[0050] 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.

[0051] The wavelengths of the first LED 30 and the second LED 40 are different in the following ways: 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.

[0052] In other words, in the first mixed light 50 from the first LED 30 and the second LED 40, the wavelengths of the first minimum peak wavelength 33 and the second minimum peak wavelength 43 are different, so the areas where their light emission intensities are low do not overlap. This makes it possible to compensate for the areas where their light emission intensities are low, resulting in the emission of light with superior color rendering.

[0053] 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 luminescence intensity is increased compared to when only the second LED 40 is used (from 0.3 to 0.53).

[0054] Furthermore, because 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. As a result, light with better color rendering can be emitted than when using the first LED 30 and the second LED 40 individually.

[0055] Furthermore, the lighting device 1 of the present invention not only has excellent color rendering properties, but also contains almost no infrared or ultraviolet components, so it can be used for lighting art exhibitions and for lighting storage rooms where paintings are kept.

[0056] It can also be used for lighting indoors for plant cultivation. This is because the lighting device 1 of the present invention, as shown in Figure 8, is similar in shape to the McCree curve, a graph that shows the average wavelength and photosynthetic efficiency of 22 plant species. In other words, it can be used for lighting in plant factories where plants are grown, and in factories that produce other products (plants) where the appearance and color are important.

[0057] <Second Embodiment> Next, a second embodiment of the present invention will be described. Hereinafter, configurations different from the first embodiment will be mainly described, while components similar to those in the first embodiment will be given the same reference numerals, and their descriptions will be omitted or simplified.

[0058] Figure 5 is a front view 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.

[0059] The lighting device 1A has a configuration substantially the same as the lighting device 1 of the first embodiment, the difference being that the LED substrate 20A has a first LED 30 and a third LED 60.

[0060] As shown in Figure 6, the third LED 60 has a continuous spectrum in the wavelength range of 410 nm to 750 nm and comprises 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 is not limited to this, and may have a correlated color temperature of 2500 K or 3500 K. In this embodiment, the average color rendering index Ra of the third LED 60 is 95.

[0061] A DC voltage is applied to the third light-emitting diode 60A from the LED substrate 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 maximum (the position of the maximum peak) in the wavelength range of 410 nm to 470 nm (the wavelength range of blue light). A blue light-emitting diode is used as the third light-emitting diode 60A.

[0062] The third phosphor film 60B is formed so as to cover the third light-emitting diode 60A. The light 60A from the third light-emitting diode is absorbed by the third phosphor film 60B and then emits light having an eighth maximum peak wavelength 62, which is the position where the emission intensity is maximum (maximum peak position) in the wavelength range of 610 nm to 700 nm (the wavelength range of red light).

[0063] 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.

[0064] Light is emitted from the third light-emitting diode 60A and the third phosphor film 60B, resulting in the emission of light having a desired correlated color temperature (3000K in this embodiment).

[0065] Furthermore, 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, it is not limited to this, and light with a desired correlated color temperature may be emitted by multiple light-emitting diodes.

[0066] The emission spectrum of the third LED 60 will now be described in detail. As shown in Figure 6, the third LED 60 has a continuous spectrum in the wavelength range of at least 410 nm to 700 nm. In Figure 6, the vertical axis represents relative emission intensity, and the horizontal axis represents wavelength (nm).

[0067] The seventh maximum peak wavelength 61 is, more specifically, in the wavelength range of 430 nm to 460 nm, with a central wavelength of approximately 445 nm. The eighth maximum peak wavelength 62 is, more specifically, in the wavelength range of 630 nm to 680 nm, with a central wavelength of approximately 660 nm.

[0068] The emission intensity at the eighth maximum peak wavelength 62 is 1 (100%), while the emission intensity at the seventh maximum peak wavelength 61 is approximately 0.5 (50%). Furthermore, 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 at the fourth minimum peak wavelength 63 is approximately 0.1 (10%). In addition, the emission intensity in the wavelength range from 470 nm to 610 nm (between the first and second wavelength ranges, the yellow and green wavelength range) is approximately between 0.1 (10%) and 0.8 (80%).

[0069] As shown in Figure 7, the emission spectrum of the second mixed light 70 from 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 it 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 from 3000 K to 5000 K, for example.

[0070] The second mixed light 70 emits light having a ninth maximum peak wavelength 71, which is the position where the emission intensity is maximum (maximum peak) in the wavelength range of 410 nm to 470 nm (the wavelength range of blue light).

[0071] Furthermore, the second mixed light 70 emits light having a 10th maximum peak wavelength 72, which has the maximum emission intensity (position of maximum peak) in the wavelength range of 610 nm to 700 nm (the wavelength range of red light).

[0072] The ninth maximum peak wavelength 71 is, more specifically, in the wavelength range of 430 nm to 460 nm, with a central wavelength of approximately 445 nm. The tenth maximum peak wavelength 72 is, more specifically, in the wavelength range of 610 nm to 660 nm, with a central wavelength of approximately 620 nm.

[0073] The emission intensity at the 10th maximum peak wavelength 72 is 1 (100%), while the emission intensity at the 9th maximum peak wavelength 71 is approximately 0.52 (52%). Furthermore, the 5th minimum peak wavelength 73, which is the position where the emission intensity of the second mixed light 70 is minimized (the position of the minimum peak) in the wavelength range from the 9th maximum peak wavelength 71 to the 10th maximum peak wavelength 72, is approximately 465 nm. The emission intensity at the 5th minimum peak wavelength 73 is approximately 0.4 (40%). In addition, the emission intensity in the wavelength range from 470 nm to 610 nm (between the first and second wavelength ranges, the yellow and green wavelength range) is approximately between 0.4 (40%) and 0.95 (95%).

[0074] The third peak wavelength 74 is in the wavelength range of 415 nm to 430 nm, with its center wavelength being 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, with its center wavelength being approximately 660 nm. The emission intensity of the fourth peak wavelength 75 is approximately 0.95 (95%). In this embodiment, the average color rendering index Ra of the second mixed light 70 is 98.

[0075] Here, the peak wavelength refers to a convex spectral portion, distinct 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 from the first light-emitting diode 30A, and the peak wavelength 75 is a portion of the light excited by the third phosphor film 60B by the light from the third light-emitting diode 60A.

[0076] 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.

[0077] The wavelengths of the first LED 30 and the third LED 60 differ in the following ways: 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.

[0078] In other words, in the second mixed light 70 from the first LED 30 and the third LED 60, the wavelengths of the first minimum peak wavelength 33 and the fourth minimum peak wavelength 63 are different, so the areas where their light emission intensities are low do not overlap. This makes it possible to compensate for the areas where their light emission intensities are low, resulting in the emission of light with superior color rendering.

[0079] 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 luminescence intensity is increased compared to when only the third LED 60 is used (from 0.1 to 0.4).

[0080] Furthermore, because 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. As a result, light with better color rendering can be emitted than when using the first LED 30 and the third LED 60 individually.

[0081] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and various modifications (for example, changing the correlated color temperature of the combined LEDs) are possible. [Explanation of Symbols]

[0082] 1…Lighting device 10... Cases 11…Light Diffusion Section 12...Electrode 20…LED board 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…6th maximum peak wavelength 53...Third minimum peak wavelength 60... The third LED 70...Second mixed light

Claims

1. An illumination device comprising a first LED and a second LED having different continuous spectra in a wavelength range of at least 410 nm to 700 nm, which emits a mixed light of light emitted from the first LED and light emitted from the second LED, The first LED has a first maximum peak wavelength which peaks in a first wavelength range of 410 nm to 470 nm, and a second maximum peak wavelength which peaks in a second wavelength range of 610 nm to 700 nm. The second LED has a third maximum peak wavelength which has the maximum peak at a wavelength different from the first maximum peak wavelength in the first wavelength range, and a fourth maximum peak wavelength which has the maximum peak at a wavelength different from the second maximum peak wavelength in the second wavelength range. 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 the spectrum of the mixed light, the maximum emission intensity in the first wavelength range is 50% or more of the maximum emission intensity in the second wavelength range. 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, is 40% or more of the maximum emission intensity in the second wavelength range. Lighting device.

2. A lighting device according to claim 1, In the spectrum of the mixed light, the maximum emission intensity in the first wavelength range is 70% or more of the maximum emission intensity in the second wavelength range. 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 is 50% or more of the maximum emission intensity in the second wavelength range. Lighting device.

3. A 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 between 3000K and 4000K. The correlated color temperature of the mixed light is between 4000K and 5000K. Lighting device.

4. A 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 correlated color temperature of the first LED is 5000K. Lighting device.

5. A 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 correlated color temperature of the second LED is 4000K. Lighting device.

6. A lighting device according to claim 1, The average color rendering index Ra of the mixed light is 90 or higher. Lighting device.

Images