JP2009111273A - Light emitting device - Google Patents

Abstract

In a light emitting device (for example, a COB module), a change in light emission chromaticity from a phosphor accompanying a temperature change is suppressed, and white light emission with high luminance and high color rendering properties and little variation due to temperature of light emission chromaticity is obtained.
A light emitting device (COB module) 10 of the present invention includes a plurality of blue LED chips 2 mounted on a device substrate 1 and a main wavelength of 545 to 575 nm excited by light from the blue LED chips 2. The phosphor layer includes one or more phosphors that emit visible light having a half-value width of 120 to 150 nm, and the phosphor exhibits a temperature of 90 to 140 ° C. in a normal operation state. This light emitting device emits white light having an average color rendering index Ra of 70 or more.
[Selection] Figure 2

Description

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

  LED lamps using light emitting diodes (LEDs) are rapidly expanding in various fields such as backlights for liquid crystal displays, mobile phones, information terminals, and indoor / outdoor advertisements. In addition, LED lamps have features such as long life and high reliability, and low power consumption, impact resistance, high purity display color, lightness, thinness, and other features. Application of is also being attempted. When such an LED lamp is applied to general illumination applications, it is important to obtain white light emission.

  Typical methods for realizing white light emission with an LED lamp are (1) a method using three LED chips that emit light in blue, green and red colors, and (2) a blue light emitting LED chip and yellow or orange light emission. (3) a method of combining an LED chip emitting ultraviolet light and a three-color mixed phosphor emitting blue, green and red light. Of these, the method (2) is generally widely used. Then, for the purpose of increasing the brightness of the LED lamp to which the method (2) described above is applied, a transparent resin mixed with a phosphor is applied onto a large number of LED chips mounted on a substrate (board). A chip-on-board (COB) structure in which a body-containing resin layer is formed has been developed.

  The LED lamp for general lighting is required to have good color rendering as an index of color appearance in addition to high luminous efficiency. Color rendering is an evaluation of the color appearance of a light source using illumination close to natural light as the reference light, and the color shift when the test color specified in JIS is illuminated with the sample light source and the reference light, respectively. The numerical value of the size is the color rendering index. 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 the color rendering index of 1 to 8, and in principle, the color rendering property is better as the value is closer to 100.

  A so-called high color rendering type white LED lamp having a high average color rendering index Ra emits light having a wavelength of about 620 nm to yellow light emitted from a yellow phosphor that emits light having a wavelength of 540 nm to 560 nm by blue light emission from the LED chip. White light with excellent color rendering properties is synthesized by adding red light from a red light emitter that emits light and green light from a green light emitter that emits light having a wavelength of about 520 nm. Conventionally, in order to increase the luminous efficiency, a combination of two or more phosphors that emit visible light with a narrow half-value width (for example, 110 nm or less) is used in combination, and the white light with high color rendering properties with little decrease in luminous efficiency is used. Has been proposed (see, for example, Patent Document 1).

However, a phosphor having a narrow half-value width used in such an LED lamp does not have a good temperature characteristic of light emission, and the chromaticity changes greatly when the temperature of the phosphor changes. In particular, in the LED lamp (COB module) having the COB structure and the LED lamp having a power LED chip, when the current supplied to the LED chip increases and the temperature of the phosphor rises accordingly, the phosphor Since the chromaticity of the emitted light greatly changes, there is a problem that a deviation (color deviation) occurs in the chromaticity of the white light emitted from the LED lamp.
Japanese Patent Application No. 2006-296801

  An object of the present invention is to provide a light emitting device, for example, a COB capable of suppressing white light emission that suppresses a change in chromaticity due to the temperature of light emission from a phosphor, and has high luminance and high color rendering properties and little variation in temperature of light emission chromaticity. To provide a module.

  The light-emitting device according to claim 1 is a substrate; a plurality of light-emitting elements disposed on the substrate; a phosphor layer excited by the light-emitting element, and excited by light emitted from the light-emitting element. Fluorescence containing one type of phosphor that emits visible light having a dominant wavelength of 545 to 575 nm and a half-value width of 120 to 150 nm, and at least a part of the phosphor exhibits a temperature of 90 to 140 ° C. in a normal operating state And a body layer, and emits white light having an average color rendering index Ra of 70 or more.

  The light-emitting device according to claim 2 is a substrate; a plurality of light-emitting elements disposed on the substrate; a phosphor layer excited by the light-emitting element, and excited by light emitted from the light-emitting element. And two or more kinds of phosphors that emit visible light having a dominant wavelength of 545 to 575 nm and a half width of 120 to 150 nm, respectively, and at least a part of the two or more kinds of phosphors is 90 in a normal operation state. A phosphor layer exhibiting a temperature of ˜140 ° C., and emitting white light having an average color rendering index Ra of 75 or more.

  The light emitting device according to claim 3 is the light emitting device according to claim 1 or 2, wherein the light emitting element is a light emitting diode chip that emits blue light.

  In the above-described inventions according to claims 1 to 3, the definitions and technical meanings of terms are as follows unless otherwise specified.

  A board | substrate is a board | substrate which has wiring parts, such as a circuit pattern and a lead terminal, for example, and a light emitting element is mounted on it. A frame having a recessed portion opened to the outside may be disposed on the substrate, and the recessed portion may be directly formed on the substrate without using the frame.

  The light emitting element emits visible light by exciting a phosphor with emitted light. Examples of the light emitting element used in the present invention include an LED chip that emits blue light having a dominant wavelength of 420 to 480 nm (for example, 460 nm) and an LED chip that emits near ultraviolet light having a dominant wavelength of 380 to 410 nm. However, the light-emitting element is not limited thereto, and various light-emitting elements can be used depending on the use of the light-emitting device, the target light emission color, etc. as long as the light-emitting element can excite the phosphor and emit visible light. Can be used.

  A phosphor is excited by light emitted from such a light emitting element (for example, blue light) to emit visible light, and a desired emission color is obtained by mixing the visible light and the light emitted from the light emitting element. It is.

  The temperature indicated by at least a part of the phosphor (hereinafter referred to as phosphor temperature) is the case where the phosphor is contained in a resin for sealing or the like and the phosphor-containing resin layer covers the semiconductor element. The junction temperature, which is the maximum temperature of the peripheral member in direct contact with the semiconductor element, shall be indicated. In addition, when the phosphor layer is disposed away from the semiconductor element, the phosphor temperature is not the junction temperature but a temperature obtained by directly measuring the phosphor.

  The light emitting device of the present invention emits good white light with no color shift when the phosphor temperature is in the range of 90 ° C to 140 ° C. In the usage mode in which the phosphor temperature is less than 90 ° C., even when a phosphor having a half-value width of less than 120 nm is used, the temperature characteristics of emission chromaticity are the same as when a phosphor having a half-value width of 120 to 150 nm is used. There is almost no difference. Moreover, the aspect in which the phosphor temperature exceeds 140 ° C. exceeds the use limit temperature of the light emitting element, the sealing resin, and the like, and these materials are deteriorated, so that sufficient light emission characteristics cannot be obtained.

  As the phosphor in the present invention, a phosphor having an emission spectrum having a dominant wavelength of 545 to 575 nm and a full width at half maximum of 120 to 150 nm is used alone or in combination of two or more. The full width at half maximum refers to the spread width (wavelength) of the spectrum at a height that is ½ of the emission peak. A phosphor having a narrow emission spectrum with a half width of less than 120 nm (for example, a silicate phosphor or a sialon phosphor) has a large change in chromaticity of light emission due to a temperature change (rise). Alternatively, when two or more kinds are mixed and used, the change in the chromaticity of white light (color shift) is larger in the mode in which the phosphor temperature is 90 to 140 ° C. than in the use mode at a lower temperature.

  When one type or two or more types of phosphors having an emission spectrum with a half width exceeding 150 nm are used, it is difficult to achieve high luminous efficiency.

  The phosphor layer is a layer that holds the phosphor, and can be formed as a layer in which the one or more phosphors are mixed and dispersed in a transparent resin such as a silicone resin or an epoxy resin. The phosphor layer can be formed so as to directly cover the outside of the light-emitting element, but it is also possible to form a transparent resin layer so as to directly cover the light-emitting element and to provide a layer containing the above-described phosphor on the transparent resin layer. It is. Furthermore, a phosphor sheet obtained by forming a phosphor-containing resin into a sheet shape and heat-curing it can be disposed on a transparent resin layer formed so as to directly cover the light emitting element.

  The average color rendering index Ra is obtained by quantifying the magnitude of the color shift when the test color is illuminated with the sample light source and the reference light. Ra of 70 or more has a sufficiently high color rendering property as a general lighting device.

  According to the light emitting device of claim 1, the phosphor contains one type of phosphor that emits visible light having a dominant wavelength of 545 to 575 nm and a half width of 120 to 150 nm, and the phosphor has a temperature of 90 to 140 ° C. Therefore, it is possible to obtain white light emission that has high color rendering properties and that suppresses changes and variations in chromaticity due to temperature changes, that is, has a small deviation (duv) from the locus of black body radiation. In addition, since the phosphor layer including the phosphor is disposed so as to cover the light emitting element group composed of a plurality of light emitting elements arranged on the substrate, the light emitting device having high luminance (a large amount of light emission) is provided. Obtainable.

  According to the light emitting device according to claim 2, the phosphor contains two or more kinds of phosphors emitting visible light having a dominant wavelength of 545 to 575 nm and a half width of 120 to 150 nm, and these phosphors are 90 to Since it is used in a high temperature range of 140 ° C., it is possible to obtain white light emission with high luminance and suppressed chromaticity change / variation due to temperature change and further improved color rendering.

  According to the light emitting device of the third aspect, it is possible to obtain white light emission with high luminance and high color rendering properties, in which changes and variations in chromaticity due to temperature changes are suppressed.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. 1 and 2 show a light emitting device according to an embodiment of the present invention. FIG. 1 is a plan view of the light emitting device, and FIG. 2 is a longitudinal sectional view of the light emitting device shown in FIG. 1 cut along the line FF.

  A light-emitting device (COB module) 10 shown in FIGS. 1 and 2 includes a package substrate, for example, a device substrate 1, and a plurality of, preferably a large number of semiconductor light-emitting elements, blue LED chips 2 mounted on the device substrate 1. A circuit pattern 3, a phosphor-containing resin layer 4, a reflective layer 31, an adhesive layer 32, a light diffusing member 33, and a reflector 34 are provided. The phosphor-containing resin layer 4 also functions as a sealing member.

  The blue LED chip 2 which is a semiconductor light emitting element is composed of, for example, a double-wire type blue LED chip using a nitride semiconductor, and is formed by laminating a semiconductor light emitting layer 2a on one surface of a light transmitting element substrate 2b. Yes. The element substrate 2b is made of, for example, a sapphire substrate. The element substrate 2b is thicker than the circuit pattern 3, for example, 90 μm.

  The semiconductor light emitting layer 2a is formed by sequentially stacking a buffer layer, an n-type semiconductor layer, a light emitting layer, a p-type cladding layer, and a p-type semiconductor layer on the main surface of the element substrate 2b. The light emitting layer has a quantum well structure in which barrier layers and well layers are alternately stacked. An n-side electrode is provided on the n-type semiconductor layer, and a p-side electrode is provided on the p-type semiconductor layer. This semiconductor light emitting layer 2a does not have a reflective film, and can emit light in both thickness directions.

  Such a blue LED chip 2 is mounted on the device substrate 1 having the circuit pattern 3 via a reflective layer 31 and an adhesive layer 32. The device substrate 1 is made of a flat plate made of metal or an insulating material, for example, a synthetic resin, and has a predetermined shape, for example, a rectangular shape, in order to obtain a light emitting area required for the light emitting device 10. When the device substrate 1 is made of a synthetic resin, it can be formed of, for example, an epoxy resin containing glass powder. When the device substrate 1 is made of metal, the heat radiation from the back surface of the device substrate 1 is improved, the temperature of each part of the device substrate 1 can be made uniform, and a semiconductor light emitting element that emits light in the same wavelength range. Variations in the emission color of a certain blue LED chip 2 can be suppressed. In addition, as a metal material which has such an effect, the material excellent in the heat conductivity of 10 W / m * K or more, specifically, aluminum or its alloy can be illustrated.

  Circuit patterns 3 on the cathode side and the anode side are respectively formed on the device substrate 1 via the reflective layer 31. The circuit pattern 3 is made of an alloy of Cu and Ni, Au, or the like. And the fluorescent substance containing resin which mixed and disperse | distributed the fluorescent substance mentioned later to the transparent resin is apply | coated and filled in the upper part and peripheral part of the blue LED chip 2, and the blue LED chip 2 is such fluorescent substance containing resin. Covered by layer 4. As the transparent resin, for example, a thermosetting resin such as a silicone resin or an epoxy resin is used.

  As the phosphor, a phosphor which is excited by blue light emitted from the blue LED chip 2 and has an emission spectrum having a dominant wavelength of 545 to 575 nm and a half width of the dominant wavelength of 120 to 150 nm is used alone or Two or more types are used in combination. When a phosphor having a narrower emission spectrum with a half-value width of less than 120 nm is used, or a mixture of two or more phosphors, the lower temperature when the phosphor temperature is as high as 90 to 140 ° C. As compared with the case of using the above, the emission chromaticity deviation (duv) increases and the color shift increases. In addition, when one type or two or more types of phosphors having an emission spectrum with a half width exceeding 150 nm are used, it is difficult to realize high luminous efficiency.

Examples of the phosphor excited by blue light and having an emission peak having a dominant wavelength of 545 to 575 nm and a half width of 120 to 150 nm include RE ₃ (Al, Ga) ₅ O ₁₂ : Ce phosphor (RE is Y, YAG phosphor such as at least one selected from Gd and La.) And oxide phosphor such as Ca ₃ Sc ₂ O ₄ : Ce phosphor. In addition, among the silicate phosphors such as AE ₂ SiO ₄ : Eu phosphor (AE represents an alkaline earth element such as Sr, Ba, Ca) phosphor, etc., the main wavelength and the half-value width of the above range. It is also possible to use a phosphor having

  The reflective layer 31 is sized so that a predetermined number of blue LED chips 2 can be disposed, and is, for example, attached to the entire surface of the device substrate 1. The reflective layer 31 can be made of a white insulating material having a reflectance of 85% or more in the wavelength region of 400 to 740 nm. As such a white insulating material, a prepreg made of an adhesive sheet can be used. Such a prepreg can be formed, for example, by impregnating a sheet base material with a thermosetting resin mixed with a white powder such as aluminum oxide. The reflective layer 31 is bonded to one surface which is the surface of the device substrate 1 by its own adhesiveness.

  The circuit pattern 3 is bonded to the surface of the reflective layer 31 opposite to the surface to which the device substrate 1 is bonded as an energization element to each blue LED chip 2. The circuit pattern 3 is formed in two rows interspersed at predetermined intervals in the longitudinal direction of the device substrate 1 and the reflective layer 31, for example, in order to connect the blue LED chips 2 in series. The end-side circuit pattern 3a located on one end side of the row of one circuit pattern 3 is integrally formed with a power feeding pattern portion 3c. Similarly, the end located on one end side of the row of the other circuit pattern 3 The side circuit pattern 3a is integrally formed with a power feeding pattern portion 3d. The power feeding pattern portions 3 c and 3 d are provided side by side at one end in the longitudinal direction of the reflective layer 31, and are separated from each other and insulated by the reflective layer 31. An electric wire (not shown) that reaches the power source is individually connected to each of the power supply pattern portions 3c and 3d by soldering or the like.

  Each blue LED chip 2 is disposed between circuit patterns 3 adjacent to each other in the longitudinal direction of the device substrate 1, and is bonded to the same surface of the white reflective layer 31 by an adhesive layer 32. Specifically, the other surface parallel to one surface of the element substrate 2 b on which the semiconductor light emitting layer 2 a is laminated is bonded to the reflective layer 31 by the adhesive layer 32. By this adhesion, the circuit pattern 3 and the blue LED chip 2 are arranged in a straight line on the same surface of the reflective layer 31, so that the side surface of the blue LED chip 2 positioned in this arrangement direction and the circuit pattern 3 are close to each other. It is provided so as to face each other. The thickness of the adhesive layer 32 can be, for example, 5 μm or less. For the adhesive layer 32, for example, a translucent adhesive having a thickness of 5 μm or less and a light transmittance of 70% or more, for example, a silicone resin-based adhesive can be suitably used.

  The electrode of each blue LED chip 2 and the circuit pattern 3 arranged close to both sides of the blue LED chip 2 are connected by a bonding wire 5. Further, the end-side circuit patterns 3 b positioned on the other end side of the two rows of circuit patterns 3 rows are also connected by the bonding wires 5. Therefore, in the case of this embodiment, each blue LED chip 2 is connected in series. The surface light source of the light emitting device 10 is formed by the device substrate 1, the reflective layer 31, the circuit pattern 3, each blue LED chip 2, the adhesive layer 32, the phosphor-containing resin layer 4, the bonding wire 6, and the like.

  The reflector 34 is not individually provided for each one or several blue LED chips 2 but is a single one that surrounds all the blue LED chips 2 on the reflective layer 31, and is formed of, for example, a rectangular frame. The blue LED chip 2 is disposed in a recess 6 formed by the frame. The reflector 34 is bonded to the reflective layer 31, and a plurality of blue LED chips 2 and a circuit pattern 3 are accommodated therein, and the pair of power feeding pattern portions 3c and 3d are positioned outside the reflector 34. ing. The reflector 34 can be formed of, for example, a synthetic resin, and the inner peripheral surface is a reflective surface. The reflecting surface of the reflector 34 can be formed by depositing or plating a metal material having a high reflectivity such as Al or Ni, or can be formed by applying a white paint having a high visible light reflectivity. Alternatively, white powder can be mixed into the molding material of the reflector 34 to make the reflector 34 itself white with high visible light reflectivity. As the white powder, a white filler such as aluminum oxide, titanium oxide, magnesium oxide, barium sulfate can be used. Note that the reflecting surface of the reflector 34 is desirably formed so as to gradually expand in the irradiation direction of the light emitting device 10.

  The phosphor-containing resin layer 4 is formed by aligning the liquid thermosetting resin obtained by mixing the above-described predetermined phosphors with a predetermined blending amount on the surface of the reflective layer 31 and in a straight line using an injection device such as a dispenser. The blue LED chips 2 and the bonding wires 5 are filled and filled so as to be evenly filled, and the thermosetting resin is cured by heating.

  In the light emitting device (COB module) 10 of the embodiment configured as described above, the electric energy applied by supplying the current is converted into blue light (for example, a main wavelength of 460 nm) and emitted by the blue LED chip 2, The emitted blue light is a longer wavelength (main wavelength 545 to 575 nm) and a wider half-value width (half-value width 120) due to the phosphor having a high temperature of 90 to 140 ° C. contained in the phosphor-containing resin layer 4. To 150 nm). Then, white light, which is a color obtained by mixing the blue light emitted from the blue LED chip 2 and the emission colors of these phosphors, is emitted from the light emitting device 10.

  In this way, in the light emitting device (COB module) 1 of the embodiment, white light emission in which Ra is 70 or more and color rendering is high and a change in chromaticity due to a temperature change is suppressed can be obtained. Further, since the phosphor layer including the phosphor is disposed so as to cover the light emitting element group composed of the plurality of blue LED chips 2 mounted on the device substrate 1, the luminance is high (the amount of emitted light is large). ) A light emitting device can be obtained.

  In addition, the light-emitting device (COB module) 10 of the embodiment of the present invention is used in such a manner that the phosphor temperature shows 90 to 140 ° C. for the following reason. That is, one type of phosphor having a main wavelength of 565 nm and a half width of 130 nm (a phosphor of Example 1 described later), a phosphor having a main wavelength of 540 nm and a half width of 120 nm, and a phosphor having a main wavelength of 575 nm and a half width of 105 nm. A phosphor containing resin obtained by mixing and dispersing a mixture (phosphor of a comparative example described later) in a silicone resin, a depth of 1.0 mm where an LED chip emitting blue light having a wavelength of 460 nm is disposed, After filling into a cup having an opening diameter of 3 mm, the silicone resin was cured. These LED lamps were made to emit light by changing the phosphor temperature in the range of 25 ° C. to 225 ° C., and the luminous efficiency (luminance) was measured using the gonio method. The measurement results are shown in FIG. The phosphor temperature refers to the junction temperature that is the highest temperature of the phosphor-containing resin layer that is in direct contact with the blue LED chip. The luminous efficiency (luminance) is a relative value when the luminous efficiency when the phosphor temperature is 25 ° C. is 100% for each phosphor.

  As can be seen from the graph of FIG. 3, in the usage mode in which the phosphor temperature is less than 90 ° C., even when the comparative phosphor, which is a mixture of phosphors having a narrow half-value width, is used, Example 1 having a wide half-value width is used. Even when the phosphor is used, there is almost no difference in temperature characteristics of luminous efficiency (luminance). Therefore, when the phosphor temperature is less than 90 ° C., the effect of using one type or two or more types of phosphors having a wide half-value width (120 to 150 nm) (suppression of color misregistration and prevention of luminance reduction due thereto) Hardly appears.

  Moreover, since the fluorescent substance temperature exceeds 140 degreeC, since it exceeds use limit temperatures, such as a light emitting element and sealing resin, these materials deteriorate and it cannot acquire sufficient light emission characteristics.

  Next, examples and comparative examples of the present invention will be described.

Examples 1 to 6 and Comparative Example Using one or two types of phosphors having the main wavelength and half-value width of light emitted from the blue LED chip (main wavelength 460 nm) shown in Tables 1 and 2, As shown, the light emitting device (COB module) 10 of FIG. 1 was produced.

  First, each phosphor was mixed and dispersed in a silicone resin at a predetermined ratio. The obtained phosphor-containing silicone resin was filled with a dispenser into the reflector 34 having an opening size of 60 mm × 60 mm, and then the silicone resin was cured. Thus, the phosphor-containing resin layer 4 having an optical path length of 1.0 mm was formed. The optical path length means the thickness of the phosphor-containing resin layer 4 on the light extraction side from the upper surface of the blue LED chip 2 (main wavelength 460 nm, 16 rows arranged, 4 straight).

  The light emitting device (COB module) 10 manufactured in this way was caused to emit light at a current value supplied to the blue LED chip 2 of 20 mA. The emission spectrum at this time was measured using a spectrophotometer (manufactured by Otsuka Electronics Co., Ltd., instantaneous spectrophotometer MCPD-7000), and the color temperature, color deviation (duv) and average color rendering index Ra were calculated from the emission spectrum. Each was calculated. These measurement results are shown in Tables 1 and 2. Further, the junction temperature corresponding to the phosphor temperature at this time (supply current value 20 mA) was measured and found to be 90 ° C.

Furthermore, the current values supplied to the blue LED chip 2 were 30 mA and 40 mA, the emission spectra at the respective current values were measured, and the color temperature and color deviation (duv) and the average color rendering index Ra were calculated from the emission spectra. . Then, for each supply current value, a fluctuation value Δduv from a deviation (duv) at a supply current value of 20 mA was obtained by the following equation.
Δduv = (deviation at 30 mA or 40 mA (duv)) − (deviation at 20 mA (duv))

  These measurement results are shown in Table 1 and Table 2, respectively. When the junction temperature corresponding to the phosphor temperature at this time was measured, the junction temperature was 115 ° C. when the supply current value was 30 mA, and the junction temperature was 130 ° C. when the supply current value was 40 mA.

  As is clear from Table 1, the light emitting devices (COB modules) obtained in Examples 1 to 3 emit one type of light (yellow light) having a dominant wavelength of 545 to 575 nm and a half width of 120 to 150 nm. Since it has a phosphor, the current value supplied to the blue LED chip increases from 20 mA to 30 mA and 40 mA, and even when the phosphor temperature rises to 90 ° C. or higher, Ra has a high color rendering property of 70 to 75 The variation of the emission chromaticity with temperature was very small, and the variation value Δduv of the deviation (duv) was extremely small.

  On the other hand, the COB module of the comparative example had a light emission chromaticity deviation (duv) of 0.0000 when the current value supplied to the blue LED chip was 20 mA, but the supply current value increased to 30 mA and 40 mA. When the phosphor temperature rose to 90 ° C. or higher, the light emission chromaticity changed greatly, and the deviation variation value Δduv exceeded the color change allowable value (± 0.0020).

  As is clear from Table 2, the light emitting devices (COB modules) obtained in Examples 4 to 6 emit light (yellow light) having a dominant wavelength of 545 to 575 nm and a half width of 120 to 150 nm. Since each type has a phosphor, the current value supplied to the blue LED chip is increased from 20 mA to 30 mA and 40 mA, and even when the phosphor temperature rises to 90 ° C. or higher, Ra is 75 to 80. And higher color rendering properties than those of Examples 1 to 3. In addition, the change in the emission chromaticity with temperature was small, and the fluctuation value Δduv of the deviation (duv) was small.

  Further, the phosphor used in Example 1 (one kind of phosphor having a main wavelength of 565 nm and a half width of 130 nm) and the phosphor used in the comparative example (a phosphor having a main wavelength of 540 nm and a half width of 120 nm and a main wavelength of 575 nm). For each of the above (a mixture with a phosphor having a half-value width of 105 nm), when the phosphor temperature (junction temperature) was increased from 25 ° C. to 120 ° C., the emission color shift (change in main wavelength) was determined. While the phosphor of Example 1 has a wavelength of −1 nm, the phosphor of Comparative Example has a color shift of light emission of −2 nm, confirming that the phosphor layer of Example 1 has less color shift.

It is a top view which shows the structure of embodiment which applied the light-emitting device of this invention to the COB module. It is the FF sectional view taken on the line of the COB module shown in FIG. It is a graph which shows the result of having measured luminous efficiency (luminance) by changing fluorescent substance temperature about each of the fluorescent substance of Example 1, and the fluorescent substance of a comparative example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... COB module, 1 ... Substrate, 2 ... Blue LED chip, 3 ... Circuit pattern, 4 ... Phosphor-containing resin layer, 5 ... Bonding wire, 31 ... Reflective layer, 32 ... Adhesive layer, 33 ... Light diffusion member, 34 ... reflector.

Claims (3)

A substrate;
A plurality of light emitting elements disposed on the substrate;
A phosphor layer that is excited by the light emitting element and is excited by light emitted from the light emitting element, and emits visible light having a dominant wavelength of 545 to 575 nm and a half width of 120 to 150 nm. And a phosphor layer in which at least a part of the phosphor exhibits a temperature of 90 to 140 ° C. in a normal operation state,
A light emitting device that emits white light having an average color rendering index Ra of 70 or more. A substrate;
A plurality of light emitting elements disposed on the substrate;
Two or more kinds of phosphors that are excited by the light emitted from the light emitting element and emit visible light having a dominant wavelength of 545 to 575 nm and a half-value width of 120 to 150 nm. And a phosphor layer in which at least a part of the two or more phosphors exhibits a temperature of 90 to 140 ° C. in a normal operation state,
A light emitting device that emits white light having an average color rendering index Ra of 75 or more.   The light emitting device according to claim 1, wherein the light emitting element is a light emitting diode chip that emits blue light.

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