JP3940750B2 - Illumination light source - Google Patents

Description

  The present invention relates to an illumination light source including a light emitting diode.

A light-emitting diode (hereinafter, referred to as “LED”) is a semiconductor element that is small, efficient, and emits brightly colored light, and has high color purity due to its narrow spectral half-value width. In recent years, blue LEDs have been put into practical use, and as a result, three colors of red, green, and blue have been prepared, and it has been possible to emit white light using the LEDs.
International Publication No. 00/19141

  Conventionally, since LED has been mainly applied as a display element, there has not been much research and development in the case of using the LED as a light source for illumination. When an LED is used as a display element, the light emission color characteristic of the self-emission emitted from the LED may be considered as a problem. However, when the LED is used as a light source for illumination, the color rendering property when illuminating an object also Need to be a problem. In fact, the LED illumination light source that has been studied up to the optimization of the color rendering properties has not yet been developed.

  Since an LED is excellent in monochromaticity, when white light emitted from the LED is used for illumination, a number of problems arise from its high color purity and material characteristics unique to the LED. For example, in order to obtain white light emission suitable for illumination, the problem of what spectral spectrum should be included in the LED light source and the light emission spectrum and light emission efficiency differ depending on the light emitting material of the LED. For example, it is necessary to use an appropriate light emitting material.

  The present invention has been made in view of such various points, and a main object thereof is to provide an LED illumination light source exhibiting high efficiency and high color rendering.

The illumination light source according to the present invention is an illumination light source including four types of light-emitting diodes, and the four types of light-emitting diodes include blue light-emitting diodes that emit blue light, blue-green light-emitting diodes that emit blue-green light, and orange light. and the emitted orange light emitting diode, Ri red light emitting diode and der emitting red, when the correlated color temperature of the illumination light source is 5000K or more, the emission of the blue-green light emitting diodes the blue light-emitting diodes than the emission intensity of the The light emission distribution is high and the light emission intensity of the red light emitting diode is higher than that of the orange light emitting diode .

  In one embodiment, the blue light emitting diode has an emission wavelength peak at 420 to 470 nm, the blue-green light emitting diode has an emission wavelength peak at 500 to 550 nm, and the orange light emitting diode is 570 to 570 nm. The red light emitting diode has an emission wavelength peak at 610 to 660 nm.

  In a preferred embodiment, the blue light emitting diode has an emission wavelength peak at 450 to 470 nm, the blue-green light emitting diode has an emission wavelength peak at 510 to 540 nm, and the orange light emitting diode is 580. The red light emitting diode has an emission wavelength peak at 625 to 650 nm.

  In one embodiment, the peak of the emission wavelength for each of the four types of light emitting diodes is a peak different from an assumed peak calculated from a theoretical simulation result.

  The illumination light source preferably has an average color rendering index of 90 or more.

  The respective evaluation test colors are determined by the illumination light source, rather than the area of the color gamut formed by connecting four points on the chromaticity coordinates where the evaluation test colors of the special color rendering indexes R9 to R12 are rendered by the reference light source. It is preferable that the area of the color gamut formed by connecting the four points on the chromaticity coordinates to be rendered is larger.

  A color in which the evaluation test color is rendered by the illumination light source with respect to an area of a color gamut formed by connecting eight points on the chromaticity coordinates where each of the evaluation test colors R1 to R8 is rendered by the reference light source Four points on the chromaticity coordinates where each of the evaluation colors of the special color rendering indexes R9 to R12 is rendered by the reference light source, rather than the ratio (Ga) of the area of the color gamut formed by connecting the eight points on the chromaticity coordinates. It is preferable that the ratio (Ga4) of the area of the color gamut formed by connecting the four points on the chromaticity coordinates where the evaluation test color is rendered by the illumination light source to the area of the color gamut formed by connecting the gamut is larger.

  The illumination light source preferably has an average color rendering index of 90 or more.

  In one embodiment, a phosphor that emits light when excited by light emitted from the light emitting diode is further provided.

  The phosphor is a green phosphor or a yellow phosphor that is excited by light emission from the blue light emitting diode and emits green to yellow light, and the phosphor has a half width wider than the half width of the light emitting diode. It preferably has an emission distribution.

  In one embodiment, the illumination light source further includes emission intensity adjusting means for adjusting an emission intensity ratio for each of the four types of light emitting diodes.

  The light emitting part of the blue light emitting diode and the light emitting part of the orange light emitting diode are provided in one chip, and the light emitting part of the red light emitting diode and the light emitting part of the blue green light emitting diode are provided. It is preferable to be provided in one chip.

  In one embodiment, the illumination light source includes a power supply that supplies power to the four types of light emitting diodes. Further, it is preferable that a heat radiating portion for radiating heat of the light emitting diode is integrally formed. Furthermore, it is preferable to further include a reflecting plate that reflects light emitted from the light emitting diode.

  According to the present invention, it includes four types of light emitting diodes: a blue light emitting diode emitting blue light, a blue green light emitting diode emitting blue green, an orange light emitting diode emitting orange, and a red light emitting diode emitting red. Therefore, it is possible to provide an LED illumination light source exhibiting high efficiency and high color rendering with an LED having the minimum number of colors.

  Before describing the embodiment of the present invention, first, the study performed by the present inventor on a conventional illumination light source using LEDs will be described.

  2. Description of the Related Art Conventionally, a three-wavelength light source that combines light emission spectra of blue, green, and red light colors is widely known as an illumination light source that achieves an ideal spectral distribution with high efficiency and high color rendering. For example, in U.S. Pat. No. 4,176,294, in order to obtain a three-wavelength band of an ideal spectral distribution with high efficiency and high color rendering, theoretically, 430 to 485 nm, 515 to 570 nm, and 588 to 630 nm It is shown that the three wavelength bands are sufficient. The patent states that this can also be realized by using a solid-state light source (Junction-type emitters, Electroluminescence).

  However, if the above-described three wavelength bands are used, a solid light-emitting light source with high efficiency and high color rendering can be theoretically realized, but in reality it is difficult to realize it. The reason is that there is no practical and highly efficient LED that emits the spectrum corresponding to the green light emission of a theoretical three-wavelength light source even when trying to realize such a light source with an actual LED. It is. That is, as shown in FIG. 1, GaN-based LEDs have an emission peak wavelength from ultraviolet to about 530 nm, and AlInGaP-based LEDs have only an emission peak wavelength in the range of 580 nm to 660 nm. An efficient and practical LED has not been realized. Therefore, there is no practical and highly efficient LED at about 530 to 575 nm. This means that there is a large lack of emission spectrum in the portion corresponding to the green light emission of the theoretical three-wavelength light emission source with high color rendering and high efficiency.

  Therefore, even if the blue, green, and red LEDs that have been used for conventional displays are simply used, a light source with excellent color rendering properties can never be obtained. When the present inventor examined an average color rendering index (Ra) of an illumination light source composed of blue, green, and red LEDs for a conventional display, about 20 from a light bulb color near 3000K to a daylight color near 6600K. Only a very low average color rendering index was shown. In other words, even if the blue LED near the peak wavelength of 470 nm, the green near the peak wavelength of 525 nm, and the red LED near the peak wavelength of 640 nm used for conventional display display are used for illumination as they are, the color rendering property is low. Only a light source can be realized.

  Not only diverting blue, green, and red LEDs for display, but also blue and peak wavelengths near the peak wavelength of 470 nm in the three wavelength bands of an ideal spectral distribution that theoretically exhibits high efficiency and high color rendering. Even when a green LED near 525 nm and a red LED near peak wavelength 615 nm were used, the average color rendering index was found to be only around 60. Since a high color rendering light source is required to have an average color rendering index of 80 or more, it is very difficult to realize a high color rendering light source composed of LEDs based on the theory of a conventional three-wavelength light source. is there.

  Based on the theory of a conventional three-wavelength light-emitting type light source, the inventors of the present application have examined why it is difficult to realize a high color rendering light source. Conventionally, a simulation for designing a high color rendering light source has been executed by setting the emission spectrum of the light source on the assumption of a Gaussian distribution type or on the assumption of an asymmetric Gaussian distribution type (asymmetrical Gaussian). . However, in this setting, there is a factor that causes an error between the actual spectral distribution and the theory. Therefore, it has been difficult to realize a high color rendering light source using LEDs.

  For example, in Japanese Patent Application Laid-Open No. 10-209504, the light emission spectrum of a light source is calculated on the assumption of a Gaussian distribution type, and when an LED is used for illumination, three wavelength bands for improving color rendering are 455 to 490 nm, 530 to It is stated that the average color rendering index is 80 or more if there is light emission in this range at 570 nm and 605 to 630 nm. The contents of this publication are simulations, and therefore the green light emission band of about 530 to 575 nm where no high-efficiency LED actually exists is assumed, but the assumption is considered for the time being. In view of the fact that the reality using the spectral distribution of the actual LED is only in the vicinity of the average color rendering index of 60, there is a large gap between the theory and the reality of the Gaussian spectral distribution that has been conventionally used for theoretical simulations. You can see that there is a gap.

  The present inventor has assumed that the light emission principle is that of light emission by an LED, and pursued this error factor from a theoretical aspect. In the case of an emission spectrum with a narrow half-value width such as an LED, the Gaussian spectral distribution is It was found that a large error occurs between the assumed spectral distribution and the actual spectral distribution. It was also found that this error becomes larger as the half width is narrower and the color purity is higher.

  The error between this theory and reality is that an asymmetrical Gaussian spectral distribution that assumes Stokes shift, etc. (in consideration of Stokes shift, etc., the emission spectrum on the longer wavelength side and the emission on the shorter wavelength side than the spectral distribution peak) It was not able to be absorbed sufficiently even if a spectrum was distorted. In other words, even when an asymmetrical Gaussian spectral distribution is used, in the case of a spectral distribution with a narrow half-value width such as an LED, a deviation occurs between theory and reality.

  In addition, the gap between theory and reality is further increased in consideration of the characteristics of actual materials and element configurations. This is because an actual LED has distortion of spectral distribution inherent to the material. Theoretically, the error of an LED having an emission peak close to both ends of the short wavelength side and the long wavelength side of the visible light emission band and the error due to the shape of the broad part of the spectral distribution cannot be absorbed in theory.

  Hereinafter, the deviation between theory and reality will be further described with reference to FIGS. 2 (a) and 2 (b). FIGS. 2A and 2B show the light emission distribution of an LED light source composed of three types of LEDs having emission peak wavelengths of 450 nm, 530 nm, and 610 nm.

  FIG. 2A shows a spectral distribution simulated by a spectral distribution of an asymmetrical Gaussian type (asymmetrical Gaussian). In the example shown in FIG. 2A, correlated color temperature = 6500 [K] and Duv = 0. The luminous flux ratio of each LED obtained by the simulation is uniquely determined to be 450 nm = 0.3277, 530 nm = 0.3820, 610 nm = 0.2903, and the average color rendering index Ra is 82.8. It becomes.

  On the other hand, FIG. 2B shows a light emission distribution based on actual measurement. That is, the spectral distribution obtained by combining the LEDs having the same emission peak wavelength and half-value width in actual measurement in response to the simulation result shown in FIG. In the example shown in FIG. 2B, the luminous flux ratio of each LED is set to 450 nm = 0.3277, 530 nm = 0.3820, and 610 nm = 0.903, as in FIG. In this case, the correlated color temperature = 5890 [K], Duv = 15, and the average color rendering index Ra was 88.6.

  The examples shown in FIGS. 2 (a) and 2 (b) are just an example. Under the application of lighting, understand the difference between conventional theoretical simulation and actual measurement when considering the spectral distribution of LEDs. I can. A number of differences between theory and reality exist in the prior art as parts that cannot be easily estimated, and have not been pointed out in the past. The inventor of the present application has considered a combination of a simulation study and a measurement study in consideration of the limitations of conventional theoretical estimation. As a result, it was found that the half-value width increases if the peak wavelength shifts to the longer wavelength side for each light emitting material. In addition, it has been found that it is effective to optimize the spectral distribution unique to the LED while applying correction based on actual measurement for distortion of the spectral distribution peculiar to each luminescent material.

  Another conventional example is disclosed in Japanese Patent Application Laid-Open No. 11-177143. This publication suggests that the average color rendering index is low when the spectral distribution of the three-wavelength emission type of blue, green, and red is the main emission wavelength, based on the actual measurement of the spectral distribution. The publication also discloses a six-wavelength light emitting type LED light source that obtains an emission spectrum to be added to the blue, green, and red three-wavelength light emission forms based on the actual measurement and has an average color rendering index Ra of 88 or more. ing.

  However, the six-wavelength light-emitting type light source (light source using six types of LEDs) has the following problems. Since LEDs have different emission characteristics and lifetime depending on the ambient temperature for each type with different emission wavelengths, the more the number of colors to be mixed, the more stable white light is emitted under various conditions. It becomes difficult to do in reality. That is, the LED has temperature characteristics and lifetime characteristics due to the material for each wavelength, and the more light is combined with a large number of LEDs to form a light source having a large number of peak wavelengths (for example, white). ), It becomes difficult to combine the LEDs. Therefore, from a practical point of view, it is desirable to realize a sufficient color rendering property with an LED having a minimum required light color. In Japanese Patent Application Laid-Open No. 11-177143, the actual measured value itself is studied, but the relationship between the emission spectral distribution and the luminous efficiency at that time is not considered. For this reason, conditions for high color rendering and high efficiency are not described.

  As mentioned above, it is as follows when the examination which this inventor performed with respect to the conventional LED illumination light source is summarized.

  1. When a conventional three-wavelength light source is realized with LEDs, there is no highly efficient and practical LED in the region corresponding to the green light emission wavelength. However, it is difficult to realize an LED illumination light source with high efficiency and high color rendering.

  2. Even if the conventional theory is applied to an LED having a narrow half-value width and high color purity, a slight error causes a large error between the theory and reality.

  3. When white light is obtained by combining a plurality of LEDs of emitted light color, excellent color rendering is easily obtained, but the light color of the illumination light due to the difference in LED temperature and life characteristics for each emitted light color It becomes difficult to control and control the constant. Therefore, it is required for practical use to realize a high-efficiency and high-color rendering LED illumination light source with a combination of minimum configurations.

  Here, FIG. 3 shows the relationship between the number of peak wavelengths of LEDs and the average color rendering index. The results shown in FIG. 3 are based on the values shown in the experiment of the present inventor and the above publication.

  It can be understood from FIG. 3 that the average color rendering index increases as the peak wavelength of the LED increases. In addition, it can be seen that a light source exhibiting sufficiently excellent color rendering can be realized with a four-wavelength light source even if it is not a six-wavelength light source. That is, a light source having a high average color rendering index that could not be overcome with a three-wavelength light emitting type LED light source using a high-efficiency LED that actually exists can be realized with a four-wavelength light source. More specifically, a four-wavelength light source that is a color rendering property group 1A (Ra ≧ 90) as referred to in the color rendering properties category of the CIE (International Commission on Illumination) and can be used sufficiently for applications that require strict color rendering properties. It can be realized with a light source. Accordingly, it has been found that it is not necessary to use a large number of kinds of LEDs of the six-wavelength light emitting type, which has been said to be necessary in the past. As can be understood from the results shown in FIG. 3, the light emission type of four wavelengths is a condition for the number of light emission peaks of the minimum LED when the current LED is used for high efficiency and high color rendering (Ra is 90 or more).

Embodiments according to the present invention will be described below with reference to the drawings. In the following drawings, components having substantially the same function are denoted by the same reference numerals for the sake of brevity. In addition, this invention is not limited to the following embodiment.
(Embodiment 1)
The illumination light source according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 4 schematically shows the configuration of the LED illumination light source according to this embodiment, and FIG. 5 schematically shows the spectral distribution of the illumination light source.

  The illumination light source shown in FIG. 4 is an illumination light source including four types of LEDs (11, 12, 13, 14). Specifically, the illumination light source of the present embodiment includes a blue LED 11 that emits blue, a blue-green LED 12 that emits blue-green, an orange LED 13 that emits orange, and a red LED 14 that emits red. .

The blue LED 11 and the blue-green LED 12 include, for example, GaN (including not only GaN but also InGaN, AlGaN, and AlInGaN. That is, the general formula In _i Ga _j Al _k N, where 0 ≦ i, 0 <j, 0 ≦ k, i + j + k = 1). The orange LED 13 and the red LED 14 are, for example, AlInGaP-based, GaAsP-based, or GaAlAs-based LEDs. Commercially available products can be used for these LEDs.

  The blue LED 11 and the blue-green LED 12 may be not only a GaN-based LED but also a ZnO-based or ZnSe-based LED. A ZnO-based LED is a light-emitting diode in which a p-type is made of copper oxide or some other metal oxide, and an n-type is made of zinc oxide to form a pn bond. In the ZnO-based LED, the wavelength can be freely set, for example, from about 380 nm to about 500 nm by changing the substance to be mixed. Further, light emitting elements that emit light by converting light emitted from a red laser diode into, for example, blue light emitted by an element made of a nonlinear optical crystal may be used as the blue LED 11 and the blue green LED 12. That is, the blue LED 11 and the blue-green LED 12 may be configured by a light emitting element including a non-linear optical crystal element and a red laser diode. The element made of this nonlinear optical crystal is made of, for example, lithium niobium and is called an SHG (second harmonic generation) element, and can convert the wavelength of the red laser into, for example, a half wavelength.

  In the present embodiment, the LEDs (11 to 14) are disposed on, for example, a plate-shaped (or cup-shaped) pedestal 21 formed as a part of the lead frame 20. The lower end (lower terminal) of the LED is disposed so as to contact the pedestal 21, and the upper end (upper terminal) of the LED is electrically connected to the lead 23 via the bonding wire 22.

  In this embodiment, the example in which the anode and the cathode that are the electrodes of the LED are provided above and below the LEDs (11 to 14) is shown, but the present invention is not limited to this, and the anode and the cathode are provided on one side of the LED. A configuration may be used. The configuration of the lead frame 20 is also an example, and a configuration in which two or more kinds of LEDs are arranged on the pedestal 21 may be used, or a configuration in which each lead frame 20 is electrically connected may be used. Moreover, although LED is wire-bonded and electrical connection is performed, it is not restricted to this, You may carry out LED flip chip mounting. In this case, the bonding wire 22 can be omitted. The lead frame 20 is electrically connected to an external circuit (for example, a lighting circuit) (not shown), and when power is supplied to the lead frame 20 to operate the LEDs (11 to 14), as shown in FIG. Illumination light having a light emission distribution can be obtained.

  As shown in FIG. 5, the spectral distribution by the illumination light source according to the present embodiment has emission peaks of the blue LED 11, the blue-green LED 12, the orange LED 13, and the red LED 14. The blue LED 11 has an emission peak at 420 to 470 nm, the blue-green LED 12 has an emission peak at 500 to 550 nm, the orange LED 13 has an emission peak at 570 to 600 nm, and the red LED 14 has 610 It has an emission peak at ˜660 nm. By combining these four types of LEDs 11 to 14, it is possible to realize an LED illumination light source having high efficiency and high color rendering (average color rendering index of 80 or more, and further 90 or more). More preferably, the blue LED 11 has an emission peak at 450 to 470 nm, the blue-green LED 12 has an emission peak at 510 to 540 nm, the orange LED 13 has an emission peak at 580 to 600 nm, and The red LED 14 has an emission peak at 625 to 650 nm.

  As can be understood from the relationship between the LED shown in FIG. 1 and the efficiency for each emission peak wavelength, the LED has a high emission efficiency of the GaN-based light emitting material on the short wavelength side, and the AlInGaP-based light emitting material on the long wavelength side. High luminous efficiency. And in the light emission band (green) of about 530-575 nm, highly efficient LED is not implement | achieved. Therefore, the configuration of the present embodiment has a great significance in realizing an LED illumination light source with high efficiency and high color rendering in practice.

  Moreover, it is also significant from the viewpoint of production / manufacturing that manufactures an LED composed of a GaN-based light emitting material. That is, since productivity is poor for an LED having an emission peak exceeding 530 nm, it is poor in productivity that an illumination light source having a very high average color rendering index of Ra 90 or more can be realized using an LED having an emission peak of 530 nm or less. You don't have to use things. Therefore, the merit in production and manufacturing is very large.

  Furthermore, if only aiming at high color rendering, it is sufficient to increase the light emission color to be combined. However, in practice, the control is complicated, so as to improve color rendering as in this embodiment. The construction of an illumination light source using four kinds of LEDs, which are a combination of the minimum emission light colors, also has great significance. The respective emission peaks of the LEDs 11 to 14 in the present embodiment are simply calculated from simulation results based on a theoretical model (for example, a model in which the emission spectrum is assumed to be a Gaussian distribution type, a model in which an asymmetric Gaussian distribution type is assumed). It is different from the peak. In addition, the suitable combination of the light emission peak of LED11-14 is mentioned later.

  6A and 6B show suitable examples of the spectral distribution of the illumination light source according to the present embodiment. 6A is an example when the correlated color temperature is relatively low (2800K), and FIG. 6B is an example when the correlated color temperature is relatively high (6500K). In the spectral distribution shown in FIG. 6, the emission peaks of the blue LED 11, the blue-green LED 12, the orange LED 13, and the red LED 14 are combinations of 455 nm, 530 nm, 585 nm, and 625 nm.

  The average color rendering index Ra of the example shown in FIG. 6A was 93, and the average color rendering index Ra of the example shown in FIG. Both are color rendering properties group 1A (Ra ≧ 90) as referred to in the color rendering properties classification of CIE (International Commission on Illumination). In other words, it can be used sufficiently for applications that require strict color rendering (for example, for art museums), both of which can be correlated by adjusting the light emission ratio (light flux ratio) of the same four types of LEDs (11 to 14). Whether the color temperature is relatively low or high, an illumination light source having an excellent color rendering property with an Ra of 90 or more can be realized.

  In order to find a combination of LEDs (11 to 14) exhibiting excellent color rendering properties as shown in FIG. 6, the inventor of the present application has four types of LEDs (11 having emission colors of blue, blue-green, orange and red). -14) were combined in a matrix for each peak wavelength of 5 nm, and various color renderings were calculated. As a result, combinations having excellent color rendering properties while having the same emission peak at all correlated color temperatures at a correlated color temperature of about 3000 K to 6500 K were as shown in Table 1 below.

The details of “Ga” and “Ga4” in Table 1 will be described later in the second embodiment, but briefly, “Ga” is a test color (R1 to R8) for calculating the average color rendering index. ), And “Ga4” is a color gamut area ratio composed of test colors (R9 to R12) for calculating the special color rendering index.

  As can be understood from Table 1, when LEDs (11 to 14) having peak emission wavelengths near 455 nm, 525 nm, 580 nm, and 625 nm are combined, the emission ratio (light flux ratio) is changed by the same LED combination. As a result, it is possible to realize a high color rendering illumination light source with Ra close to 95 in all practical correlated color temperatures. Considering the manufacturing variation of the actual LED emission peak, it can be said that the practical optimum point is around 10 nm before and after each peak emission wavelength of the above combination. That is, it is possible to realize a high color rendering illumination light source with a combination of 455 nm, 525 nm, 580 nm, and 625 nm, and a combination when each emission peak wavelength is slightly shifted (for example, about ± 5 to 10 nm). it can.

  When the average color rendering index Ra of the general light bulb is 100, Ra of the illumination light source of this embodiment is close to 95. Therefore, from the viewpoint of color rendering, replacement with a general light bulb is sufficiently possible. Moreover, in this embodiment, since the illumination light source is comprised from LED (11-14) with favorable luminous efficiency, compared with a general light bulb, the illumination light source excellent in luminous efficiency can be provided.

  In addition, it is shown that a light source with Ra = 90 or more can be realized in the correlated color temperature range usable for illumination, and further, these can be achieved only by adjusting the emission intensity of LEDs having the same emission peak. The point means that, on the premise of industrial mass production, LEDs having a specific emission peak may be mass-produced (mass production). Therefore, the illumination light source of the present embodiment has a configuration that is extremely effective for increasing the mass production effect and has a configuration that is suitable for cost reduction.

In addition, in order to obtain a high color rendering of Ra 90 or higher, when the LED illumination light source having various correlated color temperatures is configured by the LEDs 11 to 14, the LED illumination light source is not limited to the combination of 455 nm, 525 nm, 580 nm, and 625 nm, In consideration of the color shift during lighting, the emission peak of each LED may be in the respective ranges of 450 to 470 nm, 510 to 540 nm, 580 to 600 nm, and 625 to 650 nm.
(Embodiment 2)
In the present embodiment, optimization of the combination of the blue LED 11, the blue-green LED 12, the orange LED 13, and the red LED 14 will be described. According to Embodiment 1 described above, since four types of LEDs (11 to 14) are used, as described above, an LED having better color reproducibility than a conventional illumination light source using three types of LEDs is realized. can do. However, when evaluating the color reproducibility of an illumination light source composed of LEDs, the color reproducibility evaluation method becomes a problem. Hereinafter, this problem will be described.

  Compared to the light emitted from fluorescent lamps, light bulbs, and HID light sources, which are conventionally used as illumination light sources, the light emission of LEDs has a tendency to make the colors look very vivid, but the conventional average color rendering evaluation The evaluation of only the number and the special color rendering evaluation number cannot fully capture the characteristics of color rendering when an LED is used as a light source. The fact that LEDs emit light very vividly is a characteristic phenomenon when LEDs are used for illumination, and has a narrow spectral bandwidth with a narrow half-value width and no secondary emission wavelength. This is due to the characteristics of the LED that it has.

  The illumination light source of Embodiment 1 has light emission with a narrow half-value width of the LEDs (11 to 14) as shown in FIG. Therefore, it is possible to make the color look very vivid compared to a light source such as a fluorescent lamp. The inventor of the present application has succeeded in deriving a spectral distribution suitable for an LED illumination light source through numerous experiments and examinations. Hereinafter, the method for optimizing the color reproducibility of the LED illumination light source performed by the present inventor will be described first, and then an example of the optimum spectral distribution for the LED illumination light source to exhibit excellent color reproducibility will be described.

  First, the problem of evaluation based on the conventional color rendering index will be described. The conventional color rendering index is an evaluation to be performed when the color reproduction of various color rendering evaluation color charts with a reference light source such as synthetic daylight or blackbody radiation having a correlated color temperature equivalent to the light source to be evaluated is 100. It evaluates and indexes how much the color reproduction of the various color rendering evaluation color charts with the light source is different from the color reproduction with the reference light source. Therefore, the evaluation is highest when the color rendering with the evaluation light source matches the color rendering with the reference light source. If the evaluation color chart looks duller than the color rendering with the reference light source and, as a result, looks unfavorable, the color rendering evaluation is naturally lower, but conversely, the evaluation color chart looks more vivid than the color rendering with the reference light source, As a result, the color rendering evaluation also becomes low when it looks favorable. That is, there is a problem that the color rendering evaluation is lowered even when the image looks more vivid or the color looks conspicuous.

  Today, the things that surround human beings in everyday life are not only natural objects with medium saturation such as trees and stones, but also industrial products with artificially vibrant colors such as vivid blue and yellow. It's full. For this reason, when the evaluation color chart looks brighter than the color rendering with the reference light source, giving a low evaluation to the light source is not necessarily an appropriate evaluation. Therefore, the inventor of the present application has optimized the spectral distribution of the LED illumination light source in order to take advantage of the characteristics of the LED illumination light source. Hereinafter, the optimization method performed by the present inventor will be described.

  The color rendering property evaluation method of the light source has international consistency, and is disclosed in JIS Z8726 in Japan. Among them, although not defined by international standards, a method based on a color gamut area ratio is generally indicated as an authorized method as a “color rendering property evaluation method other than based on the color rendering index”. This method is a method of evaluating by the ratio of the color gamut area composed of the test colors (R1 to R8) for calculating the average color rendering index. More specifically, the chromaticity coordinates from R1 to R8 used for calculating the average color rendering index are used, and the chromaticity coordinates when 8 points on the chromaticity coordinates rendered by the reference light source are connected. This is an evaluation method in which the ratio between the upper area and the area on the chromaticity coordinates when connecting the eight points on the chromaticity coordinates rendered by the evaluation light source is determined and used as the color gamut area ratio Ga.

  According to this evaluation method, when Ga is less than 100, the color appears to be dull because the saturation is reduced. On the other hand, when Ga is greater than 100, the color appears to have increased saturation. Therefore, it tends to look vivid. As described above, when the evaluation based on the color gamut area ratio is used instead of the evaluation based on the color reproduction deviation from the reference light source, it is possible to obtain an evaluation showing a favorable appearance even when Ra is low when the image looks vivid. it can. This evaluation method seems to be an effective evaluation index for evaluating the vivid color rendering characteristic of the LED. However, when only this index is used, Ra is evaluated better when Ga is increased, but Ra evaluated using the same evaluation test color is lowered, and a sense of incongruity due to color reproduction deviation from the reference light source is increased. End up. That is, when only the Ga index is used, consistency with the Ra index cannot be obtained.

  Therefore, the inventor of the present application introduced a color gamut area ratio using R9 to R12, which are special color rendering evaluation numbers for vivid red, yellow, green, and blue, as a new evaluation index. The evaluation method based on this evaluation index will be described. By taking over the calculation method shown in JISZ8726 similar to Ga using the evaluation test colors R1 to R8 described above, R9 to R12 are substituted for the evaluation test colors R1 to R8. This is a method for obtaining the color gamut area ratio by using it. Hereinafter, in this specification, the color gamut area ratio according to the special color rendering index R9 to R12 is referred to as “Ga4”.

  Originally, R1 to R8 are selected in order to evaluate a subtle difference in appearance of a natural object, and are test colors of medium saturation. On the other hand, R9 to R12 are evaluation color charts selected for evaluating the appearance of originally vivid objects. For this reason, by using Ga4, it is possible to extract and accurately evaluate whether or not an object that the user wants to show vividly appears. In other words, for objects that require subtle and accurate color appearance with medium saturation, color reproduction that is faithful to the colors of natural objects with Ga and Ra close to 100 and vivid colors As for the appearance of an object to be color-reproduced, performing color reproduction that increases Ga4 is the optimum color reproduction. By performing such optimization, more natural color reproduction can be performed with high contrast of color saturation and sharpness.

  This inventor performed the optimization process with respect to the LED illumination light source of the said Embodiment 1, and obtained the following knowledge.

  (1) When the emission peaks of the LEDs 11 to 14 are 420 to 470 nm, 500 to 550 nm, 570 to 600 nm, and 610 to 660 nm, the average color rendering index Ra can be increased, and 450 to 470 nm, 510 to 540 nm, In the case of 580 to 600 nm and 625 to 650 nm, Ra can be further increased.

  (2) When the correlated color temperature is relatively low (less than 5000 K), and the reference light source for color rendering evaluation is blackbody radiation, the peak wavelength is short compared with the spectral distribution as shown in FIG. In order, that is, in the order of LEDs 11, 12, 13, and 14, when the light emission distribution is such that the peak intensity of the LED is increased, Ga 4 can be increased while Ra is increased, and Ga 4 can be made higher than Ga. In other words, within this range, it is possible to faithfully reproduce a medium chroma color for which subtle and precise color reproduction is desired, and vivid color reproduction can be performed for a high chroma color. From the viewpoint of increasing Ra, the peak wavelengths of the LEDs 11 to 14 are preferably in the ranges of 450 to 470 nm, 510 to 540 nm, 580 to 600 nm, and 625 to 650 nm, respectively.

  (3) When the correlated color temperature is relatively high (5000 K or higher) and the reference light source for color rendering evaluation is synthetic daylight, the peak wavelength is the shortest compared with the spectral distribution as shown in FIG. The blue LED 11 has a higher peak intensity than the blue-green LED 12 and the red LED 14 has a higher peak intensity than the orange LED 13 with respect to the blue-green LED 12 and the orange LED 13 sandwiched between the blue LED 11 and the longest red LED 14. When the emission distribution is increased, Ga4 can be increased while Ra is increased, and Ga4 can be made higher than Ga. In other words, within this range, it is possible to faithfully reproduce a medium chroma color for which subtle and precise color reproduction is desired, and vivid color reproduction can be performed for a high chroma color. As in the case where the correlated color temperature in (2) is relatively low, from the viewpoint of increasing Ra, the peak wavelengths of the LEDs 11 to 14 are 450 to 470 nm, 510 to 540 nm, 580 to 600 nm, and 625, respectively. It is suitable to be in the range of ˜650 nm.

  Examples of LED illumination light sources that have been optimized for color reproduction are shown in FIGS. 8 to 10 and Tables 2 to 4. FIG.

  FIG. 8A shows an example of the spectral distribution of the LED illumination light source optimized for the case of 3000 K as a representative of those having a low correlated color temperature. 3000K is a level close to the lower limit of the correlated color temperature in a commonly used illumination light source. In the case of 3000K, the reference light source to be compared when calculating Ra is blackbody radiation. The emission peak wavelengths of the LEDs 11, 12, 13, and 14 in this example are 455 nm, 525 nm, 580 nm, and 625 nm, respectively, and their luminous flux ratios are 1.53, 37.64, 34.83, respectively. 26.00.

  FIG. 8B is a graph showing the color gamut area ratio by Ga for the LED illumination light source having the spectral distribution shown in FIG. 8A, and FIG. 8C is the color gamut area by Ga4. It is a graph which shows ratio. In Table 1 below, in addition to the above conditions, the chromaticity values (x, y), Duv, color rendering properties (Ra, R1 to R15), and color gamut area ratio of the LED illumination light source for FIG. It shows.

  Similar to FIG. 8A, FIG. 9A shows an example of the spectral distribution of an LED illumination light source optimized for a case where the correlated color temperature is 5000K as a representative one having a medium correlated color temperature. 5000K is a point at which the reference light source to be compared switches from black body radiation to synthetic daylight when calculating Ra. The emission peak wavelengths of the LEDs 11, 12, 13, and 14 in this example are 455 nm, 525 nm, 580 nm, and 625 nm, respectively, and their luminous flux ratios are 3.54, 47.25, 30.86, respectively. 18.34.

  FIGS. 9B and 9C are graphs showing the color gamut area ratios of Ga and Ga4, respectively. Similar to Table 2, Table 3 below shows the chromaticity values (x, y), Duv, color rendering properties (Ra, R1 to R15) of the LED illumination light source for FIG. 9 in addition to the above conditions, The gamut area ratio is also shown.

  FIG. 10A shows an example of the spectral distribution of an LED illumination light source optimized for a correlated color temperature of 6700K. 6700K is a level close to the upper limit of the correlated color temperature in a commonly used illumination light source. In the case of 6700K, the reference light source to be compared in the calculation of Ra is synthetic daylight. The emission peak wavelengths of the LEDs 11, 12, 13, and 14 in this example are 455 nm, 525 nm, 580 nm, and 625 nm, respectively, and their luminous flux ratios are 4.80, 50.02, 29.46, respectively. 15.72.

  Similar to Table 2, the following Table 4 shows, in addition to the above conditions, the chromaticity values (x, y), Duv, color rendering properties (Ra, R1 to R15) of the LED illumination light source for FIG. The gamut area ratio is also shown.

  An example of an LED illumination light source that has not been optimized for color reproduction is shown in FIG. 11 and Table 5 as a reference.

  FIG. 11A shows an example of the spectral distribution of the LED illumination light source for a case where the correlated color temperature is 5000K as a representative one having a medium correlated color temperature, as in FIG. It is. The emission peak wavelengths of the LEDs 11, 12, 13, and 14 in this example are 445 nm, 515 nm, 580 nm, and 630 nm, respectively, and their luminous flux ratios are 2.01, 43.06, 39.10, respectively. 15.82.

  FIGS. 11B and 11C are graphs showing the color gamut area ratios of Ga and Ga4, respectively. In Table 5 below, in addition to the above conditions, the chromaticity values (x, y), Duv, color rendering properties (Ra, R1 to R15) and color gamut area ratio of the LED illumination light source for FIG. It shows.

  The inventor of the present application, when optimizing the color reproduction performed in the present embodiment, combines the spectral distribution of actual LEDs in a matrix at various correlated color temperatures and every wavelength of 5 nm, and optimizes it by mathematical programming (simplex method). The value was verified. When optimizing the color reproduction, when the same Ra, Ga, and Ga4 are shown, the chromaticities of various evaluation color charts are plotted as shown in FIG. Since a condition that the color deviation of the test color chart in the direction (for example, clockwise) is selected more is selected, unfavorable color deviation in the hue direction is minimized. Based on the results of FIGS. 8 to 11 and Tables 2 to 5, the findings of the inventor will be described in detail.

  1. When the emission peak of the blue LED 11 was made smaller than 450 nm, the blue test color was vividly reproduced, Ga and Ga4 were increased, and Ra was decreased. On the other hand, when it was set larger than 470 nm, the blue test color was not dull and reproduced, and Ga and Ga4 were lowered and Ra was lowered. In addition, the interval between the emission peaks with the blue-green emission becomes too narrow, and the color shift in the hue direction between the blue and blue-green color charts becomes large. From this result, it was found that the interval between the blue and blue-green emission peaks is preferably about 60 nm to 70 nm. And this is the point which raises Ra.

  However, if the same LED is used with various color temperatures in common and only the Ra is increased without considering the realization of a high color rendering light source only by changing the emission intensity, the range for the blue LED 11 is considered. Is relaxed to 420 nm to 470 nm.

  2. If the light emission peak of the blue-green LED 12 is set to the vicinity of 530 nm on the relatively long wavelength side, it works advantageously in increasing Ra. However, it was found that Ra tends to decrease when the emission peak is increased to 530 or more, for example, 540 nm or 550 nm. In addition, when the emission wavelength of the blue-green LED 12 exceeds 540 nm, the industrial yield of LEDs typified by the GaN system is lowered. Further, since the interval between the emission peaks of the blue LED 11 and the blue-green LED 12 is preferably about 60 nm to 70 nm, the lower limit of the emission peak of the blue-green LED 12 is at least 500 nm, and 510 nm when higher color rendering is desired. It is preferable to do. Here, when aiming to improve not only the efficiency in photopic vision but also the effective brightness feeling in dimmed vision or scotopic vision, the peak of the light sensitivity of human rod photoreceptors is about 505 nm. Therefore, the emission peak of the blue-green LED 12 may be positively selected in the vicinity of this wavelength.

  3. If the emission peak of the orange LED 13 is in the vicinity of 570 nm to 600 nm on the relatively short wavelength side, it works advantageously in increasing Ra. It was found that Ra tends to decrease when the emission peak has a wavelength shorter than this. When the emission wavelength of the orange LED 13 starts to fall below 580 nm, the industrial productivity of the LED represented by the AlInGaP system decreases, but when it falls below 570 nm, it further decreases. Further, when the emission peak of the orange LED 13 exceeds 600 nm, the interval between the emission peaks of the blue-green LED 12 and the orange LED 13 becomes too wide, and the interval of the emission peak between the orange LED 13 and the red LED 14 becomes too narrow. The distribution of Ga or Ga4 is distorted in the hue direction, and as a result, Ra is lowered.

  4). When the emission peak of the red LED 14 is in the vicinity of 620 nm to 630 nm, it works advantageously in increasing Ra. The lower limit of the emission peak of the red LED 14 is 610 nm when viewed moderately, and is 625 nm, which is an intermediate between 620 and 630 nm when viewed strictly. When set larger than 650 nm, the test color of red was vividly reproduced, Ga and Ga4 were increased, and Ra was decreased. On the other hand, when it was set to be smaller than 625 nm, the red test color was not dull and reproduced, and Ga and Ga4 were lowered and Ra was reduced.

  However, this range is reduced to 610 nm if only Ra is raised without considering realizing a high color rendering light source by using the same LED with various color temperatures in common and changing the emission intensity. To 660 nm. Here, in particular, considering only the case where a light source with a relatively low color temperature in which the reference light source is a black body radiation is realized, it can be seen that the optimum solution deviates specifically, even within the peak wavelength range of the red LED 14. It was found that Ra increases when the emission peak is on the long wavelength side exceeding 630 nm. This phenomenon was remarkable when the target was a low color temperature light source in which the reference light source was black body radiation.

As can be understood from FIG. 11 and Table 5, in this example, although Ra shows a good value exceeding 90, since the emission peak of the orange LED 13 is higher than the emission peak of the red LED 14, the value of Ga4 is It is smaller than the value of Ga. That is, the value of Ga is too high, and the faithful color reproducibility for a medium-saturation color for which subtle and precise color reproduction is desired is slightly deteriorated. If the focus is on making the colors appear more vivid, the Ga value may be high and Ra need not be higher than necessary. Will be available. Therefore, the range in which such an LED illumination light source can be realized is wider than the optimization range described above.
(Embodiment 3)
The illumination light source according to the third embodiment of the present invention will be described with reference to FIG. FIG. 12 schematically shows the spectral distribution of the LED illumination light source according to this embodiment.

  The LED illumination light source of the present embodiment includes a phosphor 15 that emits light when excited by light emitted from the LED, in addition to the blue LED 11, the blue-green LED 12, the orange LED 13, and the red LED 14 in the first and second embodiments. Since the phosphor 15 has a broad emission spectrum as compared with the emission spectra of the LEDs 11 to 14, the phosphor 15 can improve the color mixture of the LEDs 11 to 14. Moreover, if the phosphor 15 is provided around the LEDs 11 to 14, the color mixture of the LEDs 11 to 14 can be improved by scattering of the phosphor 15.

  The phosphor 15 in the present embodiment is a phosphor that is excited by light emission from the blue LED 11 and emits any color in the range of green to yellow, and is, for example, a yellow light-emitting phosphor or a green light-emitting phosphor. Not only the blue LED 11 but also the blue green LED 12 may be excited by light emission. As the phosphor 15, a YAG phosphor or an inorganic phosphor having a Mn emission center can be used. Further, not only the inorganic phosphor but also an organic phosphor may be used.

  As can be seen from FIG. 12, by providing the phosphor 15, it is possible to supplement the spectrum of the emission wavelength that is insufficient for the LEDs (11 to 14). The phosphor 15 has a broad emission spectrum with a wide half width, and the half width of the phosphor 15 of the present embodiment is wider than the half width of the LEDs 11 to 14 (for example, 11). Have a broad emission spectrum of 50 nm or more.

Since the illumination light source of the present embodiment includes the phosphor 15, the light color variation is suppressed so that the emitted light color does not vary even when the lighting conditions of the light-colored LEDs (11 to 14) change. can do. That is, since the LED has a spectrum with a narrow band emission, the variation of the emitted light color becomes large with respect to the change of the lighting condition of each light color LED (11-14), and as a result, the control is difficult. By combining the light emission of the light emitting phosphor 15 and the light emission of the LED, it is possible to suppress a change in the color of the emitted light that may fluctuate with respect to a change in the lighting condition of the LED of each light color.
(Embodiment 4)
An illumination light source according to a fourth embodiment of the present invention will be described with reference to FIGS. FIG. 13 schematically shows a circuit configuration of the LED illumination light source according to the present embodiment.

  The LED illumination light sources according to the first to third embodiments can be a light color variable light source by adopting the circuit configuration shown in FIG.

  The circuit 51 shown in FIG. 13 includes emission intensity adjusting means (emission intensity adjuster) 56 that adjusts the emission intensity of each of the blue LED 11, the blue-green LED 12, the orange LED 13, and the red LED 14. It has a function to adjust the emission intensity of the LED. That is, the light emission intensity adjusting means 56 can adjust the light emission intensity ratio (light flux ratio) of each LED (11-14). In the present embodiment, a variable resistor is used as the light emission intensity adjusting means 56.

  The light emission intensity adjusting means 56 may be any means that can take means for changing the power supplied to each LED. Therefore, not limited to variable resistance, means for switching fixed resistance, means for using ladder resistance, means by frequency control, means by time-division lighting, means for changing the number of connected LEDs as viewed from the power source, or A means for switching the connection method can be used.

  The circuit configuration shown in FIG. 14 is a modification of that shown in FIG. As shown in FIG. 14, if the blue LED 11 and the orange LED 12 are controlled as a set, and the blue green LED 12 and the red LED 14 are controlled as a set, the number of emission intensity adjusting means (emission intensity adjusters) can be reduced. The circuit configuration can be simplified. Each combination is such that the LEDs have complementary colors. In the case of this configuration, the first-stage emission intensity adjusting means 57 seen from the LED side is accompanied by the operation of the comparator of the GaN-based LED and the AlInGaP-based LED. Further comparison and adjustment are performed by the two-stage emission intensity adjusting means 58. Thereby, it is possible to separate the circuit operation into a form including two comparisons between the GaN-based LED and the AlInGaP-based LED and one comparison between the respective comparison operations. Therefore, the operation of the LED illumination light source of the present invention can be made surely and simple. A variety of circuits that perform such an operation can be considered, and a representative example thereof is a feedback circuit using a comparator.

  According to the configuration of the present embodiment, since the intensity ratio of the LEDs (11 to 14) can be adjusted, an arbitrary light color can be emitted. Moreover, since the light emission intensity of each LED can be varied, the brightness of the illumination light source can be easily adjusted by this configuration.

  In addition, after making LED11-14 of each emitted light color into an individual element, it is not restricted to the case where it combines and comprises an illumination light source, You may make it the structure which has arrange | positioned LED11-14 in one LED element. When the LEDs 11 to 14 are integrally configured, it is possible to reduce color mixing unevenness. That is, when each of the light-colored LEDs 11 to 14 serving as a light emitting source is configured as an individual element and compared with a case where the LEDs 11 to 14 are integrally configured as compared with a case where light is emitted at spatially separated locations. Can reduce color mixing unevenness.

On the other hand, after the LEDs 11 to 14 are fabricated as individual elements, these elements may be clustered into one unit. In the case of this configuration, there is an advantage that each LED element design can be optimally designed individually. Moreover, since the non-defective product of each LED element can be selected and clustered into one unit, the industrial yield can be improved. Furthermore, even when the output luminous flux of each LED of the emitted light color is different, the ratio of the number of clusters can be arbitrarily set by configuring each LED as an individual element, so that the degree of freedom in lamp design can be set. Can be high. As a result, even when the output light beams of the LEDs 11 to 14 are different, it is possible to simply provide an illumination light source that exhibits good characteristics. In other words, such a configuration increases the degree of freedom in lamp design rather than clustering elements in which LEDs (11 to 14) of each emission color are preliminarily incorporated in a certain element at a certain ratio. Can do.
(Embodiment 5)
The illumination light source according to the fifth embodiment of the present invention will be described with reference to FIG. FIG. 15 schematically shows the configuration of the LED illumination light source 61 according to the present embodiment.

  As shown in FIG. 15, the LED illumination light sources in the first to fourth embodiments can be combined with a power supply device 64 that supplies power to the LEDs (11 to 14) to form a unit (lamp unit or illumination device). .

  The lamp unit 61 of the present embodiment supplies power to the LED 62 configured from one or more or all or all of the LEDs 11 to 14 of the above embodiment, the reflecting plate 63 that reflects light emitted from the LED 62, and the LED 62. And a base 65 connected to the power supplier 64.

  One or a plurality of LEDs 62 can be arranged on the bottom surface of the reflector 63, and for example, about 10 to 200 can be arranged. Furthermore, when the reflecting plate 63 is thermally coupled to the LED 62, the reflecting plate 63 serves as a heat sink, which can contribute to the improvement of the heat dissipation of the LED 62. As a result, the LED 62 can be used with a longer life. As the reflecting plate 62, a diffuse reflecting plate (for example, a white reflecting plate) or a specular reflecting plate (reflecting mirror) can be used.

  In the case of the lamp unit 61 provided with about 60 LEDs 62, the inventor of the present application has a beam luminous flux (luminous flux included in the beam angle) of 60 lm, a lamp life of 10,000 hours, and a luminous efficiency of about 30 to 50 lm / W. Confirmed. This characteristic is very excellent compared with the characteristics of a conventional lamp unit that combines a conventional halogen bulb and a dichroic mirror (beam luminous flux: about 60 lm, lifetime: 2000 hours, luminous efficiency: about 15 lm / W). I understand that. Further, the LED 62 attached to the lamp unit 61 is a semiconductor element, and therefore has an advantage that it is easy to handle.

  Further, in the conventional lamp unit of the same type combining so-called blue, green and red wavelengths, the average color rendering index Ra is 20 at various correlated color temperatures (3000K, 5000K, etc.), whereas blue / blue-green. In the lamp unit 61 of this embodiment in which LEDs of orange and red in the four wavelength regions are combined, the average color rendering index Ra can be about 95 at various correlated color temperatures. Furthermore, by adopting the configuration of the fourth embodiment, the lamp unit 61 of the present embodiment can be provided as a light color variable one. In this case, for example, the light intensity adjusting means (light intensity adjusting device) 51 shown in FIG.

  Furthermore, if the power supply 64 and the LED 62 are configured to be thermally shielded by a heat insulating means such as a heat insulating material, the rate at which the heat generated by the power supply 64 is transmitted to the LED 62 can be reduced. Thereby, heating of LED can be suppressed.

  In the present embodiment, the power supply unit 64 may be provided with an AC / DC converter, for example. In the example shown in FIG. 15, a light color variable switch 66 and a brightness variable dial 67 are attached to the power supply 64 so that the light color and brightness of the illumination can be adjusted by operating these dials. It is configured.

In the present embodiment, the lamp unit 61 with the reflector 63 and the base 65 has been described, but the present invention is not limited to this. The reflector 63 and the base 65 of the lamp unit 61 can be provided or not provided depending on various uses. It is also possible to employ a configuration in which about 60 LEDs 62 are used as one unit, and that one unit is used as one light source. Moreover, you may make it the structure which uses the 1 unit in multiple numbers. The LED 62 shown in FIG. 15 is a through-hole type bullet-type element. However, the LED 62 is not limited by the shape of the element, and may be a surface-mount type chip-type element, or an LED bare chip is directly mounted on a substrate. It does not matter if it is
(Embodiment 6)
The illumination light source according to the sixth embodiment of the present invention will be described with reference to FIG.

  The LED illumination light source in Embodiments 1 to 5 can be configured as a unit in which an LED is mounted on a heat-dissipating substrate and combined with a power supply unit that supplies power to the LED. FIG. 16 schematically shows a configuration of a lamp unit (LED illumination light source) 71 according to the present embodiment.

  The lamp unit 71 of the present embodiment includes an LED 72 composed of one or more or all of the LEDs 11 to 14 of the above embodiment, a heat dissipating substrate 73 on which the LED 72 is mounted, and heat of the heat dissipating substrate. A heat sink 74 that dissipates, a reflector 75 that reflects light emitted from the LED 72, and a power supplier 76 that supplies power to the LED 72 are provided.

  One or a plurality of LEDs 72 can be arranged on the heat dissipating substrate 73, and for example, about 10 to 200 can be arranged. In the present embodiment, the LED 72 is in the form of a bare chip. When the LED 72 is thermally coupled to the heat sink 74, it is possible to contribute to the improvement in heat dissipation of the LED 72. As a result, the LED 72 can be used with a longer life. As the heat dissipation substrate 73, a glass epoxy substrate, a composite substrate, or a ceramic substrate is suitable. It is preferable that these substrates have a metal base because heat dissipation can be further improved. These substrates may be multilayer substrates.

As the reflector 73, a diffuse reflector (for example, a white reflector) or a specular reflector (reflector) can be used. Further, instead of providing the reflector 73 separately, it is also possible to use a diffused reflector as a white finish on the surface of the heat dissipating substrate, or as a mirror reflector (reflector) as a mirror finish.
(Embodiment 7)
The illumination light source according to the seventh embodiment of the present invention will be described with reference to FIG. In the present embodiment, the light emitting part of the blue LED 11 and the light emitting part of the orange LED 13 are provided in one chip, and the light emitting part of the red LED 14 and the light emitting part of the blue green LED 12 are one. It is provided in the chip. This point is different from the first to sixth embodiments. The other points are the same as in the above embodiment, and therefore, the description of the same points as in the above embodiment is omitted or simplified for the sake of simplicity. In addition, it is also possible to combine the structure of said Embodiment 1-6 with the structure of this embodiment.

  In the illumination light source of this embodiment, the light emitting layer of the blue LED 11 and the light emitting layer of the orange LED 13 are integrally configured as one LED bare chip, and the light emitting layer of the blue green LED 12 and the light emitting layer of the red LED 14 are integrated as one LED chip. It is composed. In the case of such a configuration, what normally needs to be arranged in four colored bare chips is only two bare chips. Both LEDs in one bare chip are in a complementary color relationship with each other, and the light emission positions of the two LEDs are almost the same in the form of one LED bare chip, which is more advantageous for color mixing. Furthermore, since the two are joined more thermally, the temperature between the two light emitting layers is made uniform, and both can be regarded as being thermally the same. As a result, it is easy to perform feedback control of the influence of heat on the light output. The advantage of becoming is also obtained.

  In addition, blue light emission and orange light emission are a combination of a GaN light emitting material and an AlInGaP light emitting material, and blue green light emission and red light emission can be formed by a combination of a GaN light emitting material and an AlInGaP light emitting material. It is possible to make the combination of the light emitting materials of the bare chips bonded to one the same. Therefore, since the combination of materials can be made the same, it becomes easier to perform feedback control of the influence of heat.

  First, a process for manufacturing an LED bare chip having two light emitting layers will be described with reference to FIGS.

  First, as shown in FIG. 17A, a first LED light-emitting layer 111 including at least a P-type semiconductor layer, an N-type semiconductor layer, and an active layer is formed on a substrate 116 for LED film formation.

  Next, as shown in FIG. 17B, the substrate 116 is peeled off to obtain the first LED light emitting layer 111. The substrate 116 may be peeled off as appropriate depending on the types of the substrate 116 and the LED light emitting layer. For example, polishing of the substrate 116, mechanical peeling, removal of the substrate 116 by etching, peeling due to thermal stress, laser or microwave is used. Techniques such as stripping may be employed.

  Next, as shown in FIG. 17C, when the first LED light-emitting layer 111 is attached to a substrate 116 ′ on which another LED light-emitting layer 113 is formed, an LED bare chip that emits two light emission colors is obtained. can get. Thus, after each or any of the light emitting layer of 1st LED and another LED is peeled, it bonds together and it is set as one LED bare chip. In this example, the description mainly focuses on bonding of different types of light emitting layers, but of course, bonding of the same kind of materials is also possible. In pasting, techniques such as vacuum bonding performed using high vacuum, bonding (adhesion) using an adhesive, bonding performed using pressure, bonding performed using heating, and the like can be employed. In addition, a combination of these methods can be employed.

  Hereinafter, with reference to FIGS. 18 to 21, an example of a combination pattern of bonding is illustrated. There are many variations of this bonding, but the main patterns are shown below. For convenience, the light-emitting layers of the blue LED 11, the blue-green LED 12, the orange LED 13, and the red LED 14 are referred to as light-emitting layers 111, 112, 113, and 114, respectively. You may form the fluorescent substance 15 shown in the said Embodiment 3 around these LED light emitting layers.

  FIG. 18A shows an example of a double-sided electrode structure when the substrate 116 is conductive. In this structure, one electrode is provided on the upper surface of each upper light emitting layer (111, 112) and one electrode is provided on the lower surface of each lower light emitting layer (113, 114) with the substrate 116 interposed therebetween. That's fine.

  FIG. 18B shows an example of a single-sided electrode structure when the light-emitting diode substrate is non-conductive. In this structure, two electrodes may be provided on the upper surface of each upper light emitting layer and two electrodes on the lower surface of each lower light emitting layer with the substrate 116 interposed therebetween.

  FIG. 18C shows an example in which the single-sided electrode structure and the double-sided electrode structure are combined when the substrate 116 is conductive. In the case of this structure, one electrode may be provided on the upper surface of each upper light emitting layer and two electrodes on the lower surface of each lower light emitting layer with the substrate 116 interposed therebetween.

  FIG. 19A shows an example in which LED light emitting layers are stacked on one side of each substrate 116 when the substrate 116 is conductive. In the case of this structure, one electrode may be provided on the upper surface of each upper light emitting layer and one electrode on the lower surface of each substrate 116.

  FIG. 19B shows an example in which a double-sided electrode and a single-sided LED light emitting layer are stacked on one side of each substrate 116 when the substrate 116 is conductive. In the case of this structure, it is only necessary to provide one electrode on the upper surface of each substrate 116 and two electrodes on the lower surface of each lower LED light emitting layer.

  In FIG. 19C, LED light emitting layers (111, 112) that emit light having a short wavelength are disposed on the lower side of the substrate 116, and excitation light emission is performed by light from the LED light emitting layer that emits light of the short wavelength. The LED active layer (113 ', 114') to be arranged is shown on the upper side. In the case of this structure, two electrodes may be provided on the lower surfaces of the LED light emitting layers 111 and 112, respectively.

  The structure shown in FIGS. 18 and 19 is an example of a number of possible combinations. In addition to variations in the rearrangement of the LED light-emitting layers of the respective emission colors, FIGS. 18C and 19A to 19C are used. In the structure shown in (2), there is also an inversion pattern for the vertical relationship.

  Further, instead of laminating each LED light emitting layer on one side or both sides of the substrate 116, a structure in which the LED light emitting layers are spatially juxtaposed on the same substrate 116 is also possible. An example of such a structure is shown in FIGS.

  FIG. 20A shows a structure in which LED light emitting layers (111 to 114) of the respective colors are formed on one conductive substrate 116. FIG. In the case of this structure, a common electrode may be provided on the lower side of the substrate 116, and one electrode may be provided on the upper surface of each LED light emitting layer.

  FIG. 20B shows a structure in which each color LED light emitting layer is formed on one non-conductive substrate 116. In the case of this structure, two electrodes may be provided on the upper surface of each LED light emitting layer.

  FIG. 20C shows a pattern in which the vertical relationship of the structure shown in FIG.

  FIG. 21A shows a structure in which LED light emitting layers (111 to 114) of the respective colors are formed on one conductive substrate 116. In this structure, one common electrode is provided on the lower side of the substrate 116 and one electrode is provided on the upper surface of each LED light emitting layer, and two electrodes are provided on the upper surface of each LED light emitting layer. The provided ones are mixed.

  FIG. 21 (b) shows a structure in which the LED light emitting layers are juxtaposed. In the case of this structure, the substrate 116 is not necessary, and the bonding process shown in FIG.

  FIG. 21C shows a structure in which two LED light emitting layers of double-sided electrodes are laminated as they are. Even in this structure, the substrate 116 is not necessary. Further, in the case of this concept, there may be a variation in which the LED light emitting layers of single-sided electrodes and double-sided electrodes are laminated, or a variation in which four LED light emitting layers are laminated.

  The structures shown in FIGS. 20 and 21 are also examples of many possible combinations. In addition to variations in the rearrangement of the LED light-emitting layers of the respective emission colors, FIG. 20A, FIG. 21A and FIG. There is also a reversal pattern of the vertical relationship of the structure shown in FIG.

  As the LED used in the present embodiment, a laser diode having a DBR (Distributed Bragg Reflector) configuration, a Resonant Cavity light emitting diode, or a Non-Resonant Cavity light emitting diode can be adopted. It is also possible to employ a laser diode having a configuration of Vertical Cavity Surface Emitting Laser.

  As described above, the illumination light source according to the present invention is highly efficient and highly color-rendering with an LED having the minimum number of colors, and is useful as a lamp unit or an illumination device.

It is a graph which shows typically the efficiency for every luminescence peak wavelength of LED. (A) is a graph which shows the spectral distribution simulated by the spectral distribution of asymmetrical Gaussian, (b) is a graph which shows the spectral distribution based on measurement. It is a graph which shows the relationship between the number of peak wavelength of LED, and average color rendering index Ra. It is a figure which shows typically the structure of the LED illumination light source concerning Embodiment 1. FIG. 3 is a graph schematically showing a spectral distribution of the LED illumination light source according to the first embodiment. (A) is a graph showing the spectral distribution when the correlated color temperature is relatively low, and (b) is a graph showing the spectral distribution when the correlated color temperature is relatively high. (A) is a model showing a suitable spectral distribution when the correlated color temperature is relatively low, and (b) is a model showing a suitable spectral distribution when the correlated color temperature is relatively high. (A) is a graph which shows the spectral distribution of the LED illumination light source which optimized in the case of 3000K. (B) is a graph which shows the color gamut area ratio by Ga. (C) is a graph which shows the color gamut area ratio by Ga4. (A) is a graph which shows the spectral distribution of the LED illumination light source which optimized in the case of 5000K. (B) is a graph which shows the color gamut area ratio by Ga. (C) is a graph which shows the color gamut area ratio by Ga4. (A) is a graph which shows the spectral distribution of the LED illumination light source which optimized in the case of 6700K. (B) is a graph which shows the color gamut area ratio by Ga. (C) is a graph which shows the color gamut area ratio by Ga4. (A) is a graph which shows the spectral distribution of the LED illumination light source in the case of 5000K. (B) is a graph which shows the color gamut area ratio by Ga. (C) is a graph which shows the color gamut area ratio by Ga4. It is a graph which shows typically the spectrum distribution of the LED illumination light source concerning Embodiment 3. FIG. It is a figure which shows typically the circuit structure of the LED illumination light source concerning Embodiment 4. FIG. It is a figure which shows typically the circuit structure of the LED illumination light source concerning Embodiment 4. FIG. It is a figure which shows typically the structure of the LED illumination light source (lamp unit) 61 concerning Embodiment 5. FIG. It is a figure which shows typically the structure of the LED illumination light source (lamp unit) 71 concerning Embodiment 6. FIG. (A)-(c) is process sectional drawing for demonstrating the preparation process of a LED bare chip. (A)-(c) is a figure which shows typically the cross-sectional structure of the LED bare chip in Embodiment 7. FIG. (A)-(c) is a figure which shows typically the cross-sectional structure of the LED bare chip in Embodiment 7. FIG. (A)-(c) is a figure which shows typically the cross-sectional structure of the LED bare chip in Embodiment 7. FIG. (A)-(c) is a figure which shows typically the cross-sectional structure of the LED bare chip in Embodiment 7. FIG.

Explanation of symbols

11 Blue LED
12 Blue green LED
13 Orange LED
14 Red LED
DESCRIPTION OF SYMBOLS 15 Phosphor 20 Lead frame 21 Base 22 Bonding wire 23 Lead 51 Circuit 56 Light emission intensity adjustment means (light emission intensity controller) which adjusts light emission intensity
57 First-step emission intensity adjustment means (emission intensity adjuster) as seen from the LED side
58 Second level emission intensity adjustment means (emission intensity adjuster) seen from the LED side
61, 71 Lamp unit 62, 72 LED
63 Reflector that reflects light emitted from the LED 64 Power supply 65 Base 66 Light color variable switch 67 Brightness variable dial 73 Heat radiating board 74 Heat sink 75 Reflector 76 Power supply 111, 112, 113, 114 LED light emitting layer 116 substrate

Claims (11)

An illumination light source including a blue light-emitting diode that emits blue, a blue-green light-emitting diode that emits blue-green, an orange light-emitting diode that emits orange, and a red light-emitting diode that emits red,
When the correlated color temperature of the illumination light source is 5000 K or higher, the blue light-emitting diode has a light emission intensity higher than that of the blue-green light-emitting diode, and the red light-emitting diode has a light emission intensity that is higher than that of the orange light-emitting diode. An illumination light source having a light emission distribution with a high emission intensity. The blue light emitting diode has an emission wavelength peak at 420 to 470 nm,
The blue-green light emitting diode has an emission wavelength peak at 500 to 550 nm,
The orange light emitting diode has an emission wavelength peak at 570 to 600 nm,
The illumination light source according to claim 1, wherein the red light emitting diode has a light emission wavelength peak at 610 to 660 nm. The blue light emitting diode has an emission wavelength peak at 450 to 470 nm,
The blue-green light emitting diode has an emission wavelength peak at 510 to 540 nm,
The orange light emitting diode has an emission wavelength peak at 580 to 600 nm,
The illumination light source according to claim 2, wherein the red light emitting diode has a light emission wavelength peak at 625 to 650 nm. The illumination light source according to claim 1, wherein the illumination light source has an average color rendering index of 80 or more. The illumination light source according to claim 4 , wherein the illumination light source has an average color rendering index of 90 or more. Each evaluation test color of the special color rendering index R9 to R12 is more than the area of the color gamut formed by connecting four points on the chromaticity coordinates where the color rendering is performed by the reference light source. The illumination light source according to claim 1, wherein an area of a color gamut formed by connecting values of four points on the chromaticity coordinates to be rendered is larger. A color in which the evaluation test color is rendered by the illumination light source with respect to an area of a color gamut formed by connecting eight points on the chromaticity coordinates where each of the evaluation test colors R1 to R8 is rendered by the reference light source Four points on the chromaticity coordinates where each of the evaluation colors of the special color rendering indexes R9 to R12 is rendered by the reference light source, rather than the ratio (Ga) of the area of the color gamut formed by connecting the eight points on the chromaticity coordinates. to the area of the color gamut formed by connecting a is larger in the ratio of the area of the color gamut formed by connecting the four points on the chromaticity coordinates in which the evaluation test color is color rendering by said illumination source (Ga4), according to claim 6 The illumination light source described in 1. The illumination light source according to claim 1, further comprising a phosphor that emits light when excited by light emitted from the light emitting diode. The phosphor is a green phosphor or a yellow phosphor that is excited by light emission from the blue light emitting diode and emits green to yellow light,
The illumination light source according to claim 8 , wherein the phosphor has a light emission distribution having a half width wider than a half width of the light emitting diode. And the blue light emitting diode, the blue-green light emitting diode and the orange light emitting diode and said any one of red each light emitting diode to adjust the luminous intensity ratio of the emission intensity adjusting means further from claim 1, further comprising a 9 Illumination light source described in 1. The light emitting part of the blue light emitting diode and the light emitting part of the orange light emitting diode are provided in one chip, and the light emitting part of the red light emitting diode and the light emitting part of the blue green light emitting diode are provided. , it is provided in a single chip, the illumination light source according to any one of claims 1 to 10.

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