JP2009260319A - Lighting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an lighting device which is difficult to deviate from a specified color temperature and an average color rendering index in using an LED. <P>SOLUTION: The lighting device includes: a light emitting element 2 emitting blue light; and a yellow phosphor and a red phosphor being mixed so as to be a lower color temperature than a specified color temperature value and so as to be plus (+) in deviation (duv) from the locus of black-body radiation by adding color and mixing light with the blue light. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a lighting device such as a light emitting diode.

Light emitting diode (LED: Light
When using Emitting Diode) for lighting,

As characteristics of LEDs, in addition to high luminous efficiency, a wide color temperature and color rendering properties as an index of color appearance, particularly an average color rendering index Ra are required. A lineup of Ra 80 to 85, Ra 90 or higher is required so that this color rendering property is not different from that of a fluorescent lamp or the like. Color rendering is an evaluation of the color appearance of the light source using illumination close to natural light as the reference light, and the colors when the test colors specified in JIS are illuminated with the sample light source and the reference light, respectively. The color rendering index is obtained by quantifying the magnitude of the deviation.

  The color rendering index includes an average color rendering index Ra and a special color rendering index Ri. It is expressed as an average value of 1 to 8 color rendering evaluation values. The special color rendering index Ri is the test No. Expressed as individual special color rendering evaluation values of 9 to 15. The color rendering index Ra is an index indicating whether the color of the white light source that is the reference light source is faithfully reproduced. As a rule, the color rendering index Ra is better as it is closer to 100.

  As for the color temperature, when HID lamps, light bulbs, and fluorescent lamps are taken into consideration, the same color rendering properties as those of HID lamps and three-wavelength fluorescent lamps, such as average color rendering index Ra83, and higher color rendering properties. In the average color rendering index Ra90 specification, a lineup of various color temperatures from 3000K to 6700K is required.

JP 2001-148516 A

  However, in the LED, even if the color temperature and the average color rendering index are set to the prescribed values, the color temperature and the average color rendering index may change during use, and characteristics equivalent to those of a fluorescent lamp or the like. It has become difficult to maintain.

  Accordingly, an object of the present invention is to provide an illumination device that is unlikely to deviate from a desired color temperature and average color rendering index during use when an LED is used.

  According to the first aspect of the present invention, a light emitting element that emits blue light, and the blue light and additive color mixing result in a color temperature lower than a specified color temperature and a deviation from the locus of black body radiation ( The yellow phosphor and the red phosphor are mixed so that duv) becomes plus (+).

  The lighting device according to claim 2 is the lighting device according to claim 1, wherein the color temperature lower than the specified color temperature and the plus (+) of the deviation (duv) are in accordance with the specified color temperature. It is characterized by being different.

  The illumination device according to claim 3 includes: a light emitting element that emits blue light; a yellow phosphor that emits yellow light when excited by blue light emitted from the light emitting element; and a blue light emitted from the light emitting element. A second phosphor that emits red light and / or green light by being excited by: blue light emitted from the light emitting element, yellow light emitted from the yellow phosphor, and emitted light emitted from the second phosphor And a white light set at a predetermined color temperature in the range of 2800K to 7200K. The white light has a color temperature that increases when the junction temperature of the light emitting element changes to the positive side. The white light is provided such that the deviation from the locus of black body radiation changes to the negative side when the junction temperature of the light emitting element changes to the positive side. Further, the white light is characterized in the that provided to a predetermined color temperature when the junction temperature of the light-emitting element is any value of more than 0 degrees.

  In the present invention and the following inventions, definitions and technical meanings of terms are as follows unless otherwise specified.

  A light emitting element that emits blue light emits blue light having a dominant wavelength of 420 to 480 nm (for example, 460 nm), and excites a phosphor with the emitted blue light to emit visible light. Examples of the light emitting element that emits blue light used in the present invention include, but are not limited to, a blue light emitting type LED chip.

  The phosphor is excited by the blue light emitted from the light emitting element to emit predetermined visible light, and desired light emission as an illuminating device by the additive color mixture of the visible light and the blue light emitted from the light emitting element. Get color. In the present invention, the yellow phosphor and the red phosphor may be mixed so that the color temperature is lower than the specified color temperature and the deviation (duv) from the locus of black body radiation is plus (+). . In addition, in order to improve the light emission efficiency, a green light-emitting phosphor having good specific visibility may be used. For example, a total of a green phosphor having an emission peak in a wavelength range of 510 to 530 nm, a red phosphor having an emission peak in a wavelength range of 620 to 650 nm, and a yellow phosphor having an emission peak in a wavelength range of 555 ± 10 nm. Three types of phosphors can be mixed and used. In this case, the types and blending ratios of these three phosphors are adjusted so that the average color rendering index Ra of light emission from the lighting device is high and high light emission efficiency is obtained.

  In addition, since the yellow phosphor and the green phosphor can be combined, the “second phosphor” according to claim 2 may be either a red phosphor or a green phosphor. And a state in which a red phosphor and a green phosphor are mixed.

  The “junction temperature” indicates the temperature at a predetermined location of the light emitting element, and this temperature detection is a value if the location can be detected directly. For example, the location can be detected directly. If not, a method may be used in which the value is confirmed by predicting the junction temperature during use and detecting the junction temperature indirectly. Therefore, if the light emitting element can be confirmed or estimated using the concept defined as the junction temperature of the light emitting element in a state where the light emitting element emits light, it can be appropriately defined.

  Further, in the present invention, when the junction temperature rises, the temperature of each phosphor generally tends to rise. Therefore, in realizing the present invention, it is also effective to set the color temperature using the junction temperature. .

  In addition, when using a phosphor in which a green phosphor having a peak wavelength of 510 to 530 nm, a red phosphor having a wavelength of 620 to 650 nm, and a yellow phosphor having a wavelength of 555 ± 10 nm is used, the degree of change in emission peak intensity with temperature It is preferably used as an index (temperature characteristic index) indicating the temperature characteristics of the phosphor, and the phosphors are combined in combination so that the values of this index are close, that is, the difference in temperature characteristic index is a certain value or less. . Specifically, among the phosphors of the respective colors, the emission peak intensity ratio of the phosphor with the smallest change in the emission peak intensity with temperature (predetermined temperature, for example, emission peak intensity a at 80 ° C./emission peak intensity a0 at room temperature) Where A is the emission peak intensity ratio of the phosphor with the greatest change in the emission peak intensity depending on the temperature (emission peak intensity b at a predetermined temperature, eg, 80 ° C./emission peak intensity b 0 at room temperature) is B, As a temperature characteristic index, the difference between these values (A−B) is 0.15 or less (15% or less) at a temperature of 80 ° C., 0.2 or less (20% or less) at a temperature of 100 ° C., and 120 ° C. It is preferable to make it 0.3 or less (30% or less) and 0.35 or less (35% or less) at a temperature of 170 ° C. In addition, normal temperature which is a reference temperature for obtaining the emission peak intensity ratio is a temperature appropriately set in the range of 20 to 30 ° C.

  And the change of the luminescent color (color temperature and average color-rendering evaluation number Ra) which arises by a temperature change by mix | blending and combining the phosphor whose emission peak intensity ratio difference (AB) is below the said value in this way. Can be suppressed.

  Here, the deviation (duv) represents the color shift of light emission (white light) from the illumination device as a deviation from the locus of black body radiation in the chromaticity diagram. For example, a green phosphor (for example, a peak wavelength of 520 nm), a red phosphor (for example, a peak wavelength of 650 nm), and a yellow phosphor (for example, a peak wavelength of 555 nm) are used. In this case, the change in emission chromaticity with temperature is the largest in the green phosphor, and as the phosphor temperature increases, the emission chromaticity decreases in the direction in which the x and y values in the CIE chromaticity diagram decrease (the chromaticity of blue light). Direction).

  Due to such a change in the emission color of the green phosphor, the chromaticity of the white light emitted from the LED lamp having the phosphor layer in which the phosphors of the three colors are mixed increases the color temperature and has a deviation (duv). ) In the direction of decreasing value. Therefore, when the initial color temperature is set lower than the specified value and the deviation (duv) value is set to 0.003 to 0.005 on the plus (+) side, the temperature of the phosphor increases. In addition, white light having a deviation (duv) value of 0 or very close to 0 at a desired color temperature, that is, white light having no color shift can be obtained. The color temperature lower than the specified color temperature and the plus (+) of the deviation (duv) differ depending on the specified color temperature, and are different as follows, for example.

  In the case of a color temperature of 3000K, the specified value of the color temperature is 3045 ± 175K (high color temperature side 3220K, low color temperature side 2870K), and the deviation (duv) is 0.000 ± 0.006 (plus (+) side 0. 006, minus (−) side−0.006).

  In the case of a color temperature of 4000K, the specified value of the color temperature is 3985 ± 275K (high color temperature side 4260K, low color temperature side 3710K), and the deviation (duv) is 0.001 ± 0.006 (plus (+)).

Side 0.007, minus (-) side -0.005).

  In the case of a color temperature of 5000K, the specified value of the color temperature is 5028 ± 283K (high color temperature side 5311K, low color temperature side 4745K), and the deviation (duv) is 0.002 ± 0.006 (plus (+))

Side 0.007, minus (-) side -0.004).

  When the color temperature is 6500K, the specified value of the color temperature is 6530 ± 510K (high color temperature side 7040K, low color temperature side 6020K), and the deviation (duv) is 0.003 ± 0.006 (plus (+)).

Side 0.009, minus (−) side −0.003).

  Therefore, in the present invention, when the color temperature is 3000K, the color temperature of the specified value of the color temperature is set.

More than 2870K, which is a color temperature lower than 3000K, the deviation (duv) is on the plus (+) side

It is preferable to mix the yellow phosphor and the red phosphor so that the value is 0.006 or less. The same applies to other color temperatures.

  Further, in the present invention, the color temperature change and deviation characteristics at the phosphor temperature described above are also characteristic changes accompanying temperature changes of the junction temperature (including the estimated junction temperature) when used as a lighting device. Since the same is true, for example, the ratio of each phosphor may be set so that a predetermined color temperature is obtained when the junction temperature of an arbitrary value is set to 60 degrees.

  According to the lighting device of the first or second aspect, it is possible to make it difficult to deviate from the specified color temperature and the average color rendering index when the LED is used.

  According to the illumination device of the third aspect, it becomes easy to obtain a desired color temperature and average color rendering index when the LED is used.

It is sectional drawing which shows the structure of one Embodiment which applied the illuminating device of this invention to the LED lamp. It is a top view which shows an example of the LED module which has arrange | positioned two or more LED lamps shown in FIG. FIG. 3 is a cross-sectional view taken along line AA ′ in FIG. 2. It is a graph which shows the result of having calculated | required emission peak intensity ratio at each temperature about green fluorescent substance, red fluorescent substance, and yellow fluorescent substance. It is a graph which shows the change of emission chromaticity when changing fluorescent substance temperature from room temperature to 200 degreeC about green fluorescent substance, red fluorescent substance, and yellow fluorescent substance. It is a graph which shows the temperature characteristic of the color temperature in the use condition of the LED lamp shown in FIG.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a configuration of an embodiment in which the lighting device of the present invention is applied to an LED. FIG. 2 is a diagram showing a plurality of LED lamps shown in FIG. FIG. 3 is a cross-sectional view taken along the line AA ′ of FIG. 2, and FIG. 3 is a plan view showing an example of an LED module as a lighting device arranged in a shape.

  The LED lamp 1 shown in FIG. 1 has a blue light emitting type LED chip 2 as a light emitting element. The LED chip 2 is mounted on a substrate 4 having a circuit pattern 3.

  The substrate 4 is a flat plate made of aluminum (Al), nickel (Ni), glass epoxy resin, or the like having heat dissipation and rigidity. Circuits on the cathode side and the anode side are disposed on the substrate 4 with an electrical insulating layer 5 interposed therebetween. Each pattern 3 is formed. The circuit pattern 3 is made of an alloy of Cu and Ni, Au, or the like.

  The bottom electrode of the LED chip 2 is disposed on and electrically connected to the circuit pattern 3 on one electrode side, and the bonding electrode 6 such as a gold wire is connected to the circuit pattern 3 on the other electrode side. It is electrically connected via. As an electrode connection structure of the LED chip 2, a flip chip connection structure can also be applied. According to these electrode connection structures, the light extraction efficiency to the front surface of the LED chip 2 is improved.

  On the substrate 4, a frame 8 made of resin or the like having a recess 7 is provided. The frame 8 having the recess 7 is made of a synthetic resin such as PBT (polybutylene terephthalate), PPA (polyphthalamide), PC (polycarbonate), etc., and the LED chip 2 is disposed and accommodated in the recess 7. . In the recess 7 in which the LED chip 2 is accommodated, a green phosphor having an emission peak in the wavelength range of 510 to 530 nm, a red phosphor having an emission peak in the wavelength range of 620 to 650 nm, and a wavelength of 555 ± A phosphor-containing resin in which a total of three types of phosphors, a yellow phosphor having an emission peak in the range of 10 nm, is mixed and dispersed in a transparent resin is applied and filled, and the LED chip 2 is such a phosphor. The resin layer 9 is covered. As the transparent resin, for example, a silicone resin or an epoxy resin is used.

  The green phosphor is, for example, a YAG phosphor such as RE3 (Al, Ga) 5O12: Ce phosphor (RE represents at least one selected from Y, G and La), AE2SiO4: Eu phosphor (AE is Silicate phosphors such as Ca3Sc2Si3O12: Ce phosphor, sialon-based phosphors (eg, CaXSiyAlZON: Eu2 +), and Ca3Sc2O4: Ce phosphors. It is selected from the inside.

  As the red phosphor, an oxysulfide phosphor such as a La2O2S: Eu phosphor, a nitride-based phosphor (for example, AE2Si5N8: Eu2 + or CaAlSiN3: Eu2 +) is used, but is not particularly limited.

  The yellow phosphor is, for example, a YAG phosphor such as RE3 (Al, Ga) 5O12: Ce phosphor (RE represents at least one selected from Y, Gd and La), (Tb, Al) 5O12: Ce. TAG phosphors such as phosphors, sialon phosphors (for example, CaXSiYAlZON: Eu2 +), AE2SiO4: Eu phosphors (AE represents an alkaline earth element such as Sr, Ba, Ca, etc.) and Sr3Si3O5: Eu2 + phosphors The silicate phosphor is selected according to the characteristics and application of the phosphor. As for the characteristics of each yellow phosphor, the YAG phosphor has a high emission spectrum peak obtained when excited by blue light, but has a wide half-value width (a broad emission peak), and the overall emission efficiency is slightly higher. TAG phosphors, sialon phosphors, and silicate phosphors are preferred from the viewpoint of luminous efficiency because they may decrease. That is, TAG phosphors, sialon phosphors, and silicate phosphors have a narrow half-value width of the emission spectrum and good emission efficiency. Note that the YAG phosphor is preferable in terms of a small change in light emission efficiency with respect to humidity, and a nitride phosphor such as a sialon-based phosphor is preferable in terms of a small change in light emission efficiency with respect to temperature.

  In the LED lamp 1, the applied electric energy is converted into blue light having a dominant wavelength of 420 to 480 nm (for example, 460 nm) and emitted from the LED chip 2, and the emitted blue light enters the phosphor-containing resin layer 9. It is a phosphor composed of a total of three types of contained green phosphor, red phosphor and yellow phosphor, and is converted into light having a longer wavelength. And the white light which is a color based on the blue light radiated | emitted from LED chip 2, and the luminescent color of these fluorescent substance is discharge | released from the LED lamp 1. FIG.

  In the LED lamp 1, the emission spectrum from the phosphor does not exist in the emission spectrum of the conventional LED lamp 1 together with the emission peak in the wavelength range of 510 to 530 nm and the emission peak in the wavelength range of 620 to 650 nm. In addition, since the main wavelength having a very high specific visibility has a light emission peak at 550 ± 10 nm, the energy conversion efficiency is high, so that the light emission efficiency can be improved.

  Furthermore, in an embodiment using a phosphor in which a green phosphor having a peak wavelength of 510 to 530 nm, a red phosphor having a peak wavelength of 620 to 650 nm, and a yellow phosphor having a wavelength of 555 ± 10 nm is used, among the phosphors of each color, the emission peak The difference (A−B) between the emission peak intensity ratios A and B (emission peak intensity at a predetermined temperature / emission peak intensity at room temperature) between the phosphor having the smallest intensity change due to temperature and the phosphor having the largest intensity is expressed as a temperature of 80 ° C. Is preferably 20% or less at a temperature of 100 ° C, 30% or less at a temperature of 120 ° C, and 35% or less at a temperature of 170 ° C. Then, by combining and combining phosphors having a difference in emission peak intensity ratio (A-B) equal to or less than the above value, the emission color (color temperature and average color rendering index Ra) generated when the temperature is changed. ) Can be suppressed.

  Here, FIG. 4 shows the results of determining the emission peak intensity ratio at each temperature for a green phosphor having a peak wavelength of 520 nm, a red phosphor having a peak wavelength of 650 nm, and a yellow phosphor having a peak wavelength of 555 nm. Note that the temperature of the phosphor is a measurement of the temperature of the phosphor powder, and the phosphor temperature was changed from 30 ° C. to 200 ° C. by heating the phosphor powder with a heater. In addition, the emission peak intensity of the phosphor was measured using a spectrophotometer (manufactured by JASCO Corporation; FP-6500). The emission peak intensity ratio of each phosphor was determined as a relative value with the emission peak intensity at 30 ° C. being 1.

  In addition, at each of the phosphor temperatures of 80 ° C., 100 ° C., 120 ° C., 150 ° C. and 170 ° C., the emission peak intensity ratio A of the yellow phosphor, which is the phosphor with the smallest change in the emission peak intensity due to temperature, The difference (AB) from the emission peak intensity ratio B of the green phosphor, which is the phosphor with the greatest change in the emission peak intensity with temperature, was calculated. The results are shown in Table 1.

  From the graph shown in FIG. 4 and Table 1, in the phosphor obtained by mixing the green phosphor with the peak wavelength of 520 nm, the red phosphor with the peak wavelength of 650 nm, and the yellow phosphor with the peak wavelength of 555 nm, the emission peak intensity of the yellow phosphor The difference (A−B) between the ratio A and the emission peak intensity ratio B of the green phosphor is 15% or less at a temperature of 80 ° C., 20% or less at a temperature of 100 ° C., 30% or less at a temperature of 120 ° C., and 170 ° C. It can be seen that the emission peak intensity ratio of the three color phosphors including the red phosphor falls within a certain range and has approximate temperature characteristics. And in the LED lamp which used together the fluorescent substance which approximated the temperature characteristic in this way, the change of the luminescent color (color temperature and average color rendering index Ra) by a temperature change can be suppressed.

  Further, in an embodiment using a phosphor in which a green phosphor having a peak wavelength of 510 to 530 nm, a red phosphor having a wavelength of 620 to 650 nm, and a yellow phosphor having a wavelength of 555 ± 10 nm is used, the type of phosphor of each color (that is, the peak In the determination of the wavelength) and the composition, the white light from the lighting device is adjusted to have a color temperature lower than the specified value and the deviation (duv) value is in the range of +0.003 to +0.005. Is preferred.

  FIG. 5 shows a case where the phosphor temperature is changed from room temperature (30 ° C.) to 200 ° C. for each of a green phosphor having a peak wavelength of 520 nm, a red phosphor having a peak wavelength of 650 nm, and a yellow phosphor having a peak wavelength of 555 nm. The change in emission chromaticity is shown in the CIE chromaticity diagram. As can be seen from the graph of FIG. 5, the change in emission chromaticity with temperature is greatest in the green phosphor, and the emission chromaticity decreases in the x and y values as the phosphor temperature increases (blue light chromaticity). The direction of heading towards). Then, due to such a change in emission chromaticity of the green phosphor, the chromaticity of emission from the LED lamp having the phosphor layer in which the three colors of phosphors are mixed is shifted as indicated by an arrow. As a result, the color temperature of the white light emitted from the LED lamp 1 increases and the value of the deviation (duv) decreases. Therefore, as described above, by setting the initial color temperature lower than the specified value and setting the deviation (duv) value in the range of 0.003 to 0.005 on the plus (+) side, fluorescence When the body temperature rises, white light having a desired color temperature and having a deviation (duv) of 0 or very close to 0, that is, white light with no color shift can be obtained.

  Further, in the LED lamp 1, the ratio C of the emission intensity at a wavelength of 555 ± 10 nm to the emission intensity at 460 nm which is the peak wavelength of blue light is 1.25 to 1.45 at a color temperature of 2750 to 3150 K, and the color temperature is 4000. High color rendering by adjusting to 0.9 to 1.0 at 4400K, 0.6 to 0.8 at 4750 to 5250K, and 0.3 to 0.6 at 6150 to 7150K. Higher luminous efficiency can be obtained while maintaining the properties. When the value of C is out of the above range at the above color temperature, light emission with high color rendering properties and high light emission efficiency cannot be obtained. In the above embodiment, the LED module 21 in which a plurality of LED lamps 1 are arranged in a matrix has been described. However, the present invention is not limited to this, and for example, a plurality of LED lamps 1 are arranged in a row. The LED lamps 1 may be formed in a single arrangement.

  Moreover, the concept of the state which actually turned on the LED lamp 1 in this embodiment is shown in FIG. FIG. 6 shows characteristics (changes in chromaticity x and y) of the LED lamp 1 depending on the junction temperature.

  The LED lamp 1 is such that when the junction temperature changes from low temperature to high temperature, the color temperature changes to the plus side, but the characteristic of deviation from the locus of black body radiation is that the junction temperature changes from low temperature to high temperature. , Changes to the minus side.

  Therefore, in the case of this embodiment, when the junction temperature of the LED lamp 1 is 60 degrees, it is set to be the center of the standard for a predetermined color temperature. In addition, although this junction temperature is a temperature at the time of assuming that the LED lamp 1 was normally used as an illuminating device, the junction temperature of this embodiment has a value by the method of detecting the junction temperature of a lighting state indirectly. A setting method may be used, and if it can be directly detected, a setting method may be used depending on the value, and a method for setting the junction temperature is not particularly limited.

  DESCRIPTION OF SYMBOLS 1 ... LED lamp, 2 ... LED chip, 3 ... Circuit pattern, 4 ... Board | substrate, 6 ... Bonding wire, 7 ... Recessed part, 8 ... Frame, 9 ... Phosphor containing resin layer

Claims (3)

A light emitting element that emits blue light, and the blue light and additive color mixture result in a color temperature lower than a specified color temperature and a deviation (duv) from the locus of black body radiation is plus (+) An illuminating device comprising a mixture of a yellow phosphor and a red phosphor.   The lighting device according to claim 1, wherein a color temperature lower than the specified color temperature and a plus (+) of the deviation (duv) differ according to the specified color temperature. A light emitting device emitting blue light;
A yellow phosphor that emits yellow light when excited by blue light emitted from the light emitting element;
A second phosphor that emits red light and / or green light when excited by blue light emitted from the light emitting element;
Blue light emitted from the light emitting element, yellow light emitted from the yellow phosphor, and white light set at a predetermined color temperature in a range of 2800K to 7200K by the emitted light emitted from the second phosphor and:
A lighting device comprising:
The white light is provided such that when the junction temperature of the light emitting element changes to the plus side, the color temperature also changes to the plus side.
The white light is provided such that the deviation from the locus of black body radiation changes to the negative side when the junction temperature of the light emitting element changes to the positive side,
The illumination device according to claim 1, wherein the white light is provided so as to have the predetermined color temperature when a junction temperature of the light emitting element is an arbitrary value of 0 ° C. or more.
A lighting device characterized by that.

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