WO2012035714A1

WO2012035714A1 - Led light bulb

Info

Publication number: WO2012035714A1
Application number: PCT/JP2011/004956
Authority: WO
Inventors: 恭正大屋; 達規糸賀; 勝利中川; 康博白川
Original assignee: 株式会社東芝; 東芝マテリアル株式会社
Priority date: 2010-09-14
Filing date: 2011-09-05
Publication date: 2012-03-22
Also published as: CN102959312B; JP5509333B2; CN102959312A; JPWO2012035714A1

Abstract

This LED light bulb is equipped with an LED module, a base part on which the LED module is positioned, and a globe attached to the base part. On the base part, the LED module is provided with an LED chip for emitting light in a range from ultraviolet to violet. A lighting circuit and a base are provided in the base part. The inside surface of the globe is provided with a fluorescent screen (9) for absorbing the ultraviolet to violet light emitted by the LED chip and emitting white light. The fluorescent screen (9) has at least two fluorescent body layers (11A, 11B), and the first fluorescent body layer (11A) positioned on the inner wall surface of the globe (4) contains a fluorescent body having a whitish body color.

Description

LED bulb

Embodiments of the present invention relate to an LED bulb.

2. Description of the Related Art Light emitting devices using light emitting diodes (LEDs) are widely used in lighting devices such as backlights for liquid crystal display devices, signal devices, various switches, in-vehicle lamps, and general lighting. White light emitting LED lamps that combine LEDs and phosphors are attracting attention as an alternative to incandescent bulbs, and their development is rapidly progressing. As a light bulb to which an LED lamp is applied (hereinafter referred to as an LED light bulb), for example, a globe is attached to a base portion provided with a bulb base, an LED chip is disposed in the globe, and an LED chip lighting circuit is further provided in the base portion. One having an integral lamp structure provided with a lamp is known.

In a conventional LED bulb, a combination of a blue light emitting LED chip (blue LED) and a yellow phosphor (YAG phosphor, etc.) that absorbs blue light emitted from the blue LED and emits yellow light is applied. The white light is obtained by mixing the blue light emitted from the blue LED and the yellow light emitted from the yellow phosphor by absorbing the blue light. An LED bulb combining a blue LED and a yellow phosphor has a feature that it is easy to ensure brightness. However, white light based on a mixed color of blue light from a blue LED and yellow light from a yellow phosphor is inferior in color rendering as evaluated by an average color rendering index (Ra) or the like.

LED bulbs that combine conventional blue LEDs and yellow phosphors have a light distribution that is biased toward the blue and yellow components, and the red component is insufficient. The reflected light when viewed is different from the natural color seen under sunlight. In a conventional LED bulb, light emitted from a blue LED is used to generate white light, and thus the luminance of the entire bulb tends to be uneven. For this reason, it is difficult to reduce glare of the light bulb, local glare, so-called glare. In an LED bulb combining a blue LED and a yellow phosphor, it has been proposed to form a phosphor film on the inner surface of the globe. In this case, the appearance color when not lit is a phosphor film (yellow phosphor). It will be limited to colors close to the body color.

JP 2005-005546 A JP 2009-170114 A

The problem to be solved by the present invention is to provide an LED bulb that achieves an improvement in color rendering and a reduction in glare, and allows the appearance color when not lit to be white or a color close thereto. is there.

The LED bulb according to the embodiment includes an LED module, a base portion on which the LED module is installed, and a globe attached to the base portion so as to cover the LED module. The LED module includes an ultraviolet or purple LED chip mounted on a substrate. The base portion is provided with a lighting circuit for lighting the LED chip and a base electrically connected to the lighting circuit. A fluorescent film is provided on the inner side of the globe so as to be separated from the LED chip. The phosphor film has two or more phosphor layers, and the first phosphor layer provided on the inner wall surface of the globe contains a phosphor having a white body color.

It is a figure which shows the LED light bulb by 1st Embodiment in a partial cross section. It is a front view which shows the LED light bulb by 2nd Embodiment. It is a figure which shows an example of the light distribution angle of the LED bulb of embodiment. It is a figure which shows an example of the light distribution angle of the LED bulb which covered the LED chip with the resin layer containing a fluorescent substance. It is sectional drawing which shows the structural example of the fluorescent film in the LED bulb of embodiment. It is sectional drawing which shows the other structural example of the fluorescent film in the LED bulb of embodiment.

Hereinafter, the LED bulb according to the embodiment will be described with reference to the drawings. FIG. 1 is a partial cross-sectional view showing the configuration of the LED bulb according to the first embodiment. FIG. 2 is a view showing an LED bulb according to the second embodiment. The LED bulb 1 shown in these drawings includes an LED module 2, a base portion 3 on which the LED module 2 is installed, a globe 4 attached on the base portion 3 so as to cover the LED module 2, and the base portion 3. A base 6 attached to the lower end through an insulating member 5 and a lighting circuit (not shown) provided in the base 3 are provided.

The LED module 2 includes an ultraviolet or purple LED chip 8 mounted on a substrate 7. A plurality of LED chips 8 are surface-mounted on the substrate 7. For the LED chip 8 emitting ultraviolet to purple light, a light emitting diode of InGaN, GaN, AlGaN or the like is used. A wiring network (not shown) is provided on the surface of the substrate 7 (and further inside if necessary), and the electrodes of the LED chip 8 are electrically connected to the wiring network of the substrate 7. A wiring (not shown) is drawn out on the side surface or bottom surface of the LED module 2, and this wiring is electrically connected to a lighting circuit (not shown) provided in the base portion 3. The LED chip 8 is lit by a DC voltage applied through a lighting circuit.

On the inner surface of the globe 4 is provided a fluorescent film 9 that absorbs ultraviolet or violet light emitted from the LED chip 8 and emits white light. The emission color of the LED bulb 1 is determined by the combination of the emission wavelength of the LED chip 8 and the phosphor constituting the fluorescent film 9. In obtaining white light in combination with the UV to purple LED chip 8, the phosphor film 9 is composed of a mixed phosphor (BGR or BYR phosphor) containing a blue phosphor, a green to yellow phosphor, and a red phosphor. It is preferable to do. The mixed phosphor may further contain at least one phosphor selected from a blue-green phosphor and a deep red phosphor. The phosphor film 9 includes a mixed phosphor that can obtain white light only by light emission from the phosphor film 9 (not including light emitted from the LED chip 8).

The shape of the globe 4 is not particularly limited, and a dome shape as shown in FIG. 1 or a eggplant shape as shown in FIG. 2 can be applied. Although illustration of the structure in the globe 4 is omitted in FIG. 2, the LED bulb 1 shown in FIG. 2 has the same configuration as the LED bulb 1 shown in FIG. 1 except that the shape of the globe 4 is different. The globe 4 is preferably formed of a material having a transparent or white body color with a visible light transmittance of 90% or more, such as glass or resin. Thereby, the white light emitted from the fluorescent film 9 can be efficiently extracted outside the bulb. Moreover, the external appearance color at the time of the non-lighting of the LED bulb 1 mentioned later can be made favorable. The globe 4 has a size equivalent to, for example, an incandescent bulb.

The fluorescent film 9 in the LED bulb 1 of this embodiment is provided on the inner surface of the globe 4 so as to be separated from the LED chip 8, unlike the LED module in which the conventional phosphor particles are dispersed in the sealing resin of the LED chip. It has been. The electrical energy applied to the LED bulb 1 is converted into ultraviolet to violet light by the LED chip 8, and further converted into light having a longer wavelength by the fluorescent film 9, and emitted as white light. The white light emitted from the LED bulb 1 is constituted only by the light emission of the fluorescent film 9, unlike a conventional LED bulb combining a blue LED and a yellow phosphor.

In the LED bulb 1, the fluorescent film 9 provided on the entire inner surface of the globe 4 emits light. Therefore, unlike the LED module in which the conventional phosphor particles are dispersed in the sealing resin, the entire fluorescent film 9 emits light. The white light spreads from the fluorescent film 9 in all directions. Furthermore, unlike a conventional LED light bulb combining a blue LED and a yellow phosphor, white light is obtained only by light emission from the phosphor film 9, so that local luminance unevenness and the like can be suppressed. As a result, uniform and soft white light can be obtained without glare. That is, the glare of the LED bulb 1 can be greatly reduced as compared with a conventional LED bulb combining a blue LED and a yellow phosphor.

When an LED chip 8 that emits ultraviolet to purple light is used as an excitation source for the LED bulb 1, the fluorescent film 9 is composed of various phosphors, unlike a conventional LED bulb that combines a blue LED and a yellow phosphor. can do. That is, since the selection range of the phosphor species constituting the fluorescent film 9 is widened, the color rendering property of white light emitted from the LED bulb 1 can be enhanced. Specifically, white light having a correlated color temperature of 6500 K or less and an average color rendering index Ra of 85 or more can be easily obtained. By obtaining such white light, it is possible to improve the practicality of the LED bulb 1 as an alternative to the incandescent bulb.

The LED chip 8 may be any LED of ultraviolet to violet emission type (emission peak wavelength is 350 to 430 nm), but an LED having an emission peak wavelength in the range of 370 to 415 nm and a half width of the emission spectrum of 10 to 15 nm. It is preferable to use a chip 8. A combination of such an LED chip 8 and a phosphor film 9 composed of the above-described mixed phosphor (BGR or BYR phosphor, and further mixed blue phosphor or deep red phosphor as required). When used, stable white light can be obtained for the correlated color temperature (emission color) regardless of the output variation of the LED chip 8, and the yield of the LED bulb 1 can be increased. In the conventional combination of a blue LED and a yellow phosphor, the output variation of the LED chip directly affects the correlated color temperature (light emission color), and thus the yield of the LED bulb is likely to be reduced.

The plurality of LED chips 8 mounted on the substrate 7 are preferably covered with a transparent resin layer 10. That is, the LED module 2 preferably includes a plurality of LED chips 8 mounted on the substrate 7 and a transparent resin layer 10 provided on the substrate 7 so as to cover the plurality of LED chips 8. For the transparent resin layer 10, for example, a silicone resin or an epoxy resin is used, and it is preferable to use a silicone resin having excellent ultraviolet resistance. Thus, by covering the plurality of LED chips 8 with the transparent resin layer 10, the light emitted from each LED chip 8 propagates to each other, and local light intensity that contributes to glare is alleviated. The light extraction efficiency can be increased.

Furthermore, by providing the fluorescent film 9 that emits white light on the inner surface of the globe 4, the light distribution angle of the LED bulb 1 can be increased. In addition, it is possible to suppress a decrease in luminance over time due to a temperature rise of the fluorescent film 9 or the like. Here, the light distribution angle indicates the spread of light around the bulb, and if the light distribution angle is small, even if the luminance directly under the bulb is high, the overall light bulb feels insufficient. Is. The light distribution angle in this embodiment is obtained by obtaining an angle at which the luminance becomes ½ with respect to the central luminance of the bulb on both the left and right sides, and adding the angles of both. In the case of left-right symmetry, the value is twice the one-side angle.

That is, in the structure in which the LED chip is covered with a resin layer containing a conventional phosphor, the energy radiated from the LED chip is converted into visible light by the phosphor in the resin layer, and this visible light is changed from the resin layer to various kinds of light. Diffuse in the direction. However, the light that travels horizontally with the surface of the substrate on which the LED chip is mounted travels straight, and does not spread on the back side (below the substrate) of the substrate. For this reason, as shown in FIG. 4, the light distribution angle of the LED bulb which covered the LED chip with the resin layer containing the conventional fluorescent substance is about 120 degree | times.

In a conventional LED bulb combining a blue LED and a yellow phosphor, etc., when a phosphor film made of a yellow phosphor or the like is formed on the inner surface of the globe, the light emission from the phosphor film diffuses to the surroundings, so the phosphor is contained. The light distribution angle is larger than that of the LED bulb in which the LED chip is covered with the resin layer. However, the light emitted from the blue LED that constitutes a part of the white light has high straightness and is transmitted to the outside through the globe in this state, so that it does not spread to the back side (below the substrate) of the substrate. . Therefore, there is a limit to improving the light distribution angle of the LED bulb.

In contrast, the LED bulb 1 of the embodiment causes the entire fluorescent film 9 provided on the inner surface of the globe 4 to emit light, and white light is obtained only by light emission from the fluorescent film 9. For this reason, white light spreads from the fluorescent film 9 in all directions. That is, since all of the light emitting components constituting the white light are emitted inside the globe 4 and the white light is diffused from the entire surface of the fluorescent film 9 to the surroundings, the spread of the white light itself to the back of the bulb is increased. Therefore, the light distribution angle of the white light of the LED bulb 1 can be increased more effectively. As shown in FIG. 3, the light distribution angle of the LED bulb 1 is 200 degrees or more.

With regard to the decrease in luminance over time caused by the temperature increase of the phosphor film 9, in the structure in which the LED chip is covered with a conventional phosphor-containing resin layer, when the LED bulb is continuously lit, the LED chip temperature increases. The temperature of the phosphor tends to rise. For this reason, luminance degradation is likely to occur due to the temperature rise of the phosphor. On the other hand, by providing the fluorescent film 9 on the inner surface of the globe 4 so as to be separated from the LED chip 8, even when the temperature of the LED chip 8 is increased, the temperature increase of the fluorescent film 9 can be suppressed. When there is a sufficient distance between the fluorescent film 9 and the LED chip 8, for example, the temperature of the fluorescent film 9 rises only to around 60 ° C. Accordingly, it is possible to suppress a decrease in luminance over time while the LED bulb 1 is lit.

As described above, the fluorescent film 9 is a mixed phosphor (BGR or BYR phosphor) containing a blue phosphor, a green to yellow phosphor, and a red phosphor, and further, a blue-green phosphor and a deep red phosphor as required. It is comprised with the mixed fluorescent substance containing at least 1 sort (s) chosen from a body. Each phosphor constituting the mixed phosphor is combined with ultraviolet to violet light from the LED chip 8, the color temperature and color rendering property (average color rendering index Ra, etc.) of the obtained white light, and when the LED bulb 1 is not lit. It is preferable to use the following phosphor from the viewpoint of the appearance color and the like.

As the blue phosphor, a phosphor having an emission peak wavelength in the range of 430 to 460 nm is used. For example, a europium (Eu) activated alkaline earth chlorophosphate phosphor having a composition represented by the formula (1) is used. It is preferable to use it.
General _{_{formula: (Sr 1-xyz Ba x}} Ca y Eu z) 5 (PO 4) 3 · Cl ... (1)
(Wherein x, y and z are numbers satisfying 0 ≦ x <0.5, 0 ≦ y <0.1, 0.005 ≦ z <0.1)

As the green to yellow phosphor, a phosphor having an emission peak wavelength in the range of 490 to 580 nm is used. For example, europium (Eu) and manganese (Mn) activated alkaline earth having a composition represented by the formula (2) Aluminate phosphors, europium (Eu) and manganese (Mn) activated alkaline earth silicate phosphors having the composition represented by formula (3), cerium having the composition represented by formula (4) Ce) activated rare earth aluminate phosphor, europium (Eu) activated sialon phosphor having a composition represented by formula (5), and europium (Eu) activated having a composition represented by formula (6) It is preferable to use at least one selected from sialon phosphors.

General _{_{formula: (Ba 1-xyz Sr x}} Ca y Eu z) (Mg 1-u Mn u) Al 10 O 17 ... (2)
(In the formula, x, y, z, and u satisfy 0 ≦ x <0.2, 0 ≦ y <0.1, 0.005 <z <0.5, and 0.1 <u <0.5. Is the number to do)
General _{_{formula: (Sr 1-xyzu Ba x}} Mg y Eu z Mn u) 2 SiO 4 ... (3)
(Wherein x, y, z and u are 0.1 ≦ x ≦ 0.35, 0.025 ≦ y ≦ 0.105, 0.025 ≦ z ≦ 0.25, 0.0005 ≦ u ≦ 0. 0.02)
General _{_{_{formula: RE 3 A x Al 5-}}} xy B y O 12: Ce z ... (4)
(In the formula, RE represents at least one element selected from Y, Lu, and Gd, A and B are paired elements, and (A, B) is (Mg, Si), (B, Sc), (B, In), and x, y, and z are x <2, y <2, 0.9 ≦ x / y ≦ 1.1, 0.05 ≦ z ≦ 0.5. Is a number that satisfies
General formula: (Si, Al) ₆ (O, N) ₈ : Eu _x (5)
(Wherein x is a number satisfying 0 <x <0.3)
General formula: (Sr _1-x Eu _x ) _α Si _β Al _γ O _δ N _ω (6)
(Where x, α, β, γ, δ, and ω are 0 <x <1, 0 <α ≦ 3, 12 ≦ β ≦ 14, 2 ≦ γ ≦ 3.5, 1 ≦ δ ≦ 3, 20 ≦ ω ≦ 22)

As the red phosphor, a phosphor having an emission peak wavelength in the range of 580 to 630 nm is used. For example, a europium (Eu) activated lanthanum oxysulfide phosphor having a composition represented by the formula (7), a formula (8 ) Europium (Eu) and bismuth (Bi) activated yttrium oxide phosphors having the composition represented by formula (9), europium (Eu) activated couun phosphor having the composition represented by formula (9), and formula (10) It is preferable to use at least one selected from europium (Eu) -activated sialon phosphors having a composition represented by:

The general _{_{formula: (La 1-xy Eu x}} M y) 2 O 2 S ... (7)
(In the formula, M represents at least one element selected from Sm, Ga, Sb, and Sn, and x and y satisfy 0.08 ≦ x <0.16 and 0.000001 ≦ y <0.003. Is the number to do)
General formula: (Y _1-xy Eu _x Bi _y ) ₂ O ₃ (8)
(Wherein x and y are numbers satisfying 0.01 ≦ x <0.15 and 0.001 ≦ y <0.05)
General formula: (Ca _1-xy Sr _x Eu _y ) SiAlN ₃ (9)
(Wherein x and y are numbers satisfying 0 ≦ x <0.4 and 0 <y <0.5)
General formula: (Sr _1-x Eu _x ) _α Si _β Al _γ O _δ N _ω (10)
(Where x, α, β, γ, δ, and ω are 0 <x <1, 0 <α ≦ 3, 5 ≦ β ≦ 9, 1 ≦ γ ≦ 5, 0.5 ≦ δ ≦ 2, 5 ≦ ω ≦ 15)

As the blue-green phosphor, a phosphor having a light emission peak wavelength in the range of 460 to 490 nm is used. For example, europium (Eu) and manganese (Mn) activated alkaline earth having the composition represented by the formula (11) It is preferable to use a silicate phosphor.
General _{_{formula: (Ba 1-xyzu Sr x}} Mg y Eu z Mn u) 2 SiO 4 ... (11)
(Wherein x, y, z and u are 0.1 ≦ x ≦ 0.35, 0.025 ≦ y ≦ 0.105, 0.025 ≦ z ≦ 0.25, 0.0005 ≦ u ≦ 0. 0.02)

As the deep red phosphor, a phosphor having an emission peak wavelength in the range of 630 to 780 nm is used. For example, a manganese (Mn) -activated magnesium fluorogermanate phosphor having a composition represented by the formula (12) is used. It is preferable to use it.
General formula: αMgO · βMgF ₂ · (Ge _1−x Mn _x ) O ₂ (12)
(In the formula, α, β, and x are numbers satisfying 3.0 ≦ α ≦ 4.0, 0.4 ≦ β ≦ 0.6, and 0.001 ≦ x ≦ 0.5)

The ratio of each phosphor composing the mixed phosphor is appropriately set according to the emission color of the LED bulb 1, etc., for example, the mixed phosphor is a blue phosphor in the range of 10 to 60% by mass, Blue-green phosphor in the range of 0 to 10% by mass, green to yellow phosphor in the range of 1 to 30% by mass, red phosphor in the range of 30 to 90% by mass, and deep red in the range of 0 to 35% by mass It is preferable to contain the phosphor so that the total amount of each phosphor is 100% by mass. According to such a mixed phosphor, a wide range of white light having a correlated color temperature of 6500K to 2500K can be obtained with the same fluorescent species. In the case of a combination of a conventional blue LED and a yellow phosphor, it is difficult to adjust the light bulb color of 2800K including the deviation with only a combination of two colors, and a red phosphor that emits light by blue excitation should be added. Is required.

By the way, in conventional incandescent bulbs, transparent glass, milky white glass, etc. are used for the material of the globe, and it is common sense that the appearance of the bulb globe is transparent or white for the user, and it has been familiar for many years Color. On the other hand, depending on the type of phosphor in the LED bulb, the external color when not lit may be yellow or orange. In particular, in a conventional LED light bulb combining a blue LED and a yellow phosphor, when the phosphor film is formed on the inner surface of the globe, an appearance color close to the body color of the phosphor (yellow phosphor, etc.) constituting the phosphor film tends to be obtained. .

The appearance color of the LED bulb when not lit is not directly related to the light emission characteristics of the lamp, but it gives a misunderstanding that the appearance color when not lit is the same as the emission color of the bulb, or a specific color. If it is limited to, various requests for LED bulbs cannot be answered, and the commercial value is reduced. For this reason, the external color when the LED bulb is not lit is preferably white or transparent, and even when it is colored, it is desired to be as close to white as possible.

In the LED electrode 1 of this embodiment, the phosphor film 9 has two or more phosphor layers. For example, as shown in FIG. 5, the phosphor film 9 has a first phosphor layer 11A provided on the inner wall surface of the globe 4 and a second phosphor layer 11B provided thereon. Yes. Alternatively, as shown in FIG. 6, the phosphor film 9 includes a first phosphor layer 11 </ b> A provided on the inner wall surface of the globe 4, and second and third phosphor layers 11 </ b> B provided in order on the first phosphor layer 11 </ b> B. 11C. The phosphor film 9 may have four or more phosphor layers 11.

Among the phosphor layers 11 described above, the first phosphor layer 11A provided directly on the inner wall surface of the globe 4, in other words, the first phosphor layer 11A located at the outermost layer has a white body color. It contains one or more phosphors. The emission color of the phosphor contained in the first phosphor layer 11A is not particularly limited as long as the body color (the color of the phosphor powder itself) is a white phosphor. The body color of the phosphor contained in the phosphor layers (11B, 11C) other than the first phosphor layer 11A is not particularly limited, and the phosphor contained in the first phosphor layer 11A What is necessary is just 1 type, or 2 or more types of fluorescent substance which can obtain white light emission in combination.

For example, even if the body color of the phosphor contained in the second phosphor layer 11B or the third phosphor layer 11C is dark or dark, the outermost first phosphor layer 11A has a body color. By configuring with a white phosphor, the color of the first phosphor layer 11A is dominant in the appearance color of the globe 4 when not lit. Therefore, it is possible to realize the LED light bulb 1 having a hue of white to light green or light yellow when it is not lit. Thus, it becomes possible to raise the commercial value of the LED bulb 1 by bringing the appearance color when the LED bulb 1 is not lit close to the incandescent bulb.

The phosphor contained in the first phosphor layer 11A has a * of −35 or more and +15 or less, b * of −10 or more and +30 or less, when the body color is expressed in the L * a * b * color system. L * preferably has a body color of +40 or more. By configuring the first phosphor layer 11A with the phosphor having such a body color, the appearance color when the LED bulb 1 is not lit can be white to light green or light yellow. The L * a * b * color system (Elster, Aster, and Beaster color systems) is a method used to represent object colors. It was standardized by the International Commission on Illumination (CIE) in 1976, and JIS Z -8729. L * represents lightness, and a * and b * represent hue and saturation. Larger L * indicates brighter. a * and b * indicate the color direction, a * indicates the red direction, -a * indicates the green direction, b * indicates the yellow direction, and -b * indicates the blue direction.

Of the numerical values of the L * a * b * color system representing the body color of the phosphor contained in the first phosphor layer 11A, if a * is less than −35, a strong green body color is obtained, and +15 is set. Beyond that, it becomes a reddish body color. When b * is less than −10, the body color becomes strong blue, and when it exceeds +15, the body color becomes strong yellow. When L * is less than +40, the body color is inferior in brightness. In any case, the appearance color when the LED bulb 1 is not lit becomes a dark color or a dark color with a low commercial value. As for the body color of the phosphor contained in the first phosphor layer 11A, it is more preferable that a * is −5 to +5, b * is −8 to +15 and L * is 70 or more. This L * a * b * means that the body color of the phosphor is closer to white. Therefore, by configuring the first phosphor layer 11A with such a phosphor, the appearance color when the LED bulb 1 is not lit can be made closer to white.

Table 1 shows the body color of each phosphor described above. The body colors shown in Table 1 are obtained by applying each phosphor alone to the inner surface of the globe and expressing the body color of each phosphor film in the L * a * b * color system. The body color (L * a * b *) is an average value of values measured by using a spectrophotometer CM2500d manufactured by Konica Minolta Co., Ltd. and by directly contacting the colorimetric unit with any three points on the surface of the fluorescent film. . The body color of each phosphor was measured using a phosphor having an arbitrary representative composition within the composition range allowed for each phosphor. Although the body color of the phosphor differs due to subtle compositional deviations within the allowable composition range, the body color difference due to the phosphor type and emission color is better than the body color difference due to the composition difference within the tolerance range. large. For this reason, in Table 1, comparative evaluation is performed for each representative composition.

The body colors of the 12 types of fluorescent films shown in Table 1 are roughly divided into three groups. The phosphors marked with ◎ and ○ in the table have white or a body color similar to white (light green, light yellow, etc.) and can be used as the phosphor to be contained in the first phosphor layer 11A described above. It is a thing. In particular, the phosphor marked with ◎ has a body color close to white, and is therefore suitable as a phosphor to be contained in the first phosphor layer 11A. Since the phosphors marked with x have body colors such as deep yellow, dark green, and dark pink, they cannot be used as the phosphors contained in the first phosphor layer 11A. For this reason, the fluorescent substance which attached | subjected x mark is used as a fluorescent substance contained in the 2nd fluorescent substance layer 11B and the 3rd fluorescent substance layer 11C.

The first phosphor layer 11A is composed of Eu-activated alkaline earth chlorophosphate phosphor, Eu and Mn-activated alkaline earth aluminate phosphor, Eu-activated lanthanum oxysulfide phosphor, Eu and Bi-activated oxidation. It is preferable to contain at least one selected from an yttrium phosphor and an Mn-activated magnesium fluorogermanate phosphor. Eu-activated alkaline earth chlorophosphate phosphor, Eu- and Bi-activated yttrium oxide phosphor And at least one selected from Mn-activated magnesium fluorogermanate phosphors is more preferable.

The first phosphor layer 11A preferably contains only a phosphor having a white body color as described above, but the amount does not affect the color of the first phosphor layer 11A (the first phosphor layer 11A). As long as it is about 1% by mass or less of the total amount of phosphors to be contained in the phosphor layer 11A). Various combinations can be applied to the first phosphor layer 11A and the other phosphor layers (11B, 11C). The other phosphor layers (11B, 11C) only need to be capable of obtaining white light emission in combination with the first phosphor layer 11A, and the phosphor layers contained in the other phosphor layers (11B, 11C). There are no particular restrictions on the emission color or type.

For example, when the first phosphor layer 11A is composed of an Eu-activated alkaline earth chlorophosphate phosphor that is a blue phosphor, the other phosphor layers (11B and 11C) have a fluorescence color other than blue. It may be composed of a body or a mixed phosphor containing a blue phosphor. When the first phosphor layer 11A is composed of Eu and Bi activated yttrium oxide phosphors which are red phosphors, the other phosphor layers (11B and 11C) are composed of phosphors having emission colors other than red. Alternatively, a mixed phosphor including a red phosphor other than Eu and Bi-activated yttrium oxide phosphors may be used. Thus, the phosphors contained in the other phosphor layers (11B, 11C) can be appropriately selected within a range where white light emission can be obtained.

The film thickness of the fluorescent film 9 is preferably in the range of 80 to 800 μm. When the LED chip 8 emitting ultraviolet to violet light is used as the excitation source of the fluorescent film 9, it is preferable to suppress leakage of ultraviolet rays from the globe 4. The ultraviolet rays leaking from the globe 4 may adversely affect printed matter, food, medicine, human body, etc. existing in the vicinity of the LED bulb 1 or in the arrangement space. When the thickness of the fluorescent film 9 is less than 80 μm, the leakage amount of ultraviolet rays increases. When the film thickness of the fluorescent film 9 exceeds 800 μm, the brightness of the LED bulb 1 decreases.

According to the fluorescent film 9 having a thickness of 80 to 800 μm, the brightness of the LED bulb 1 is reduced while reducing the amount of ultraviolet rays (energy amount of ultraviolet rays) leaking from the globe 4 to, for example, 0.3 mW / nm / lm or less. Can be suppressed. The film thickness of the fluorescent film 9 is more preferably in the range of 150 to 600 μm. The thickness of the first phosphor layer 11A in the phosphor film 9 is 40 μm or more so that the appearance color of the globe 4 when not lit is the same color as the body color of the first phosphor layer 11A. Is preferred. If the thickness of the first phosphor layer 11A is less than 40 μm, it reflects the body color of the other phosphor layers (11B, 11C), and other phosphors with respect to the appearance color of the globe 4 when not lit. The body color of the layer (11B, 11C) may become dominant.

The LED bulb 1 of this embodiment is manufactured as follows, for example. First, a phosphor slurry used for forming the first phosphor layer 11A and a phosphor slurry used for forming other phosphor layers (11B, 11C) are prepared. The phosphor slurry is prepared, for example, by mixing phosphor powder with a binder resin such as silicone resin, epoxy resin, or urethane resin, and filler such as alumina or silica. The mixing ratio of the phosphor and the binder resin is appropriately selected depending on the type and particle size of the phosphor. For example, when the phosphor is 100 parts by mass, the binder resin is in the range of 20 to 1000 parts by mass. Is preferred. It is preferable to appropriately set the type, average particle size, mixing ratio, etc. of the phosphor from the above-described condition range according to the target white light.

Next, the phosphor slurry for the first phosphor layer 11A and the phosphor slurry for the other phosphor layers (11B, 11C) are sequentially applied to the inner surface of the globe 4. The phosphor slurry is applied by, for example, a spray method, a dip method, or a method of rotating the globe 4, and uniformly applied to the inner surface of the globe 4. Next, the first phosphor layer 11 </ b> A and the other phosphor layers (on the inner surface side of the globe 4 are formed on the inner surface of the globe 4 by drying the laminated film of the coating films of the phosphor slurries using a heating device such as a dryer or an oven. 11B, 11C). Thereafter, the target LED bulb 1 is manufactured by attaching the globe 4 having the fluorescent film 9 to the base portion 3 on which the LED module 2 and the base 6 are installed.

Next, specific examples and evaluation results will be described.

(Examples 1 to 7)
First, as a blue (B) phosphor, an Eu-activated alkaline earth chlorophosphate ((Sr _0.604 Ba _0.394 Eu _0.002 ) ₅ (PO ₄ ) ₃ Cl) phosphor, blue-green (BG) fluorescence having an average particle size of 40 μm Eu and Mn-activated alkaline earth silicate ((Sr _0.225 Ba _0.65 Mg _0.0235 Eu _0.1 Mn _0.0015 ) ₂ SiO ₄ ) phosphor having an average particle diameter of 20 μm as a body, and an average particle diameter as a green to yellow (GY) phosphor There were prepared Eu and Mn-activated alkaline earth silicate _{_{17μm ((Sr 0.675 Ba 0.25 Mg}} 0.0235 Eu 0.05 Mn 0.0015) 2 SiO 4) phosphor (GY2).

Further, as red (R) phosphor, Eu-activated lanthanum oxysulfide ((La _0.9 Eu _0.1 ) ₂ O ₂ S) phosphor (R1) having an average particle size of 45 μm, Eu and Bi-activated having an average particle size of 4 μm. Yttrium oxide ((Y _0.89 Eu _0.1 Bi _0.01 ) ₂ O ₃ ) phosphor (R2), Eu-activated sialon ((Sr _0.6 Eu _0.4 ) ₂ Si ₇ Al ₄ ON ₁₄ ) phosphor (R4) having an average particle diameter of 11 μm ), A Mn-activated magnesium fluorogermanate (3.5MgO.0.5MgF _2. (Ge _0.75 Mn _0.25 ) O ₂ ) phosphor having an average particle size of 12 μm was prepared as a deep red (DR) phosphor.

Applying the combination of phosphors shown in Table 2, the first phosphor layer and the second phosphor layer were formed on the inner surface of the globe as follows. First, the phosphor powder for the first phosphor layer was dispersed in a silicone resin as a binder resin, and then defoamed to prepare a first phosphor slurry. Similarly, the phosphor powder for the second phosphor layer was dispersed in a silicone resin as a binder resin, and then defoamed to prepare a second phosphor slurry.

Next, an amount of the first phosphor slurry having a desired film thickness was put into the globe, and the globe was rotated while changing the angle so as to spread uniformly on the inner surface of the globe. Using an infrared heater or a dryer, heating was performed until the first phosphor slurry began to harden and the coating film did not flow. Next, the second phosphor slurry in an amount to achieve a desired film thickness was put into the globe, and the globe was rotated while changing the angle in the same manner. Similarly, heating was performed until the phosphor slurry began to harden and the coating film did not flow. Then, it heat-processed on condition of about 100 degreeC x 5 hours using oven etc., and the coating film of the 1st and 2nd fluorescent substance slurry was hardened | cured completely. The thickness of the phosphor film was 300 to 600 μm, and the thickness of the first phosphor layer was 80 to 300 μm.

The LED module uses 112 LED chips having an emission peak wavelength of 405 nm and an emission spectrum half-value width of 15 nm, these LED chips are surface-mounted on a substrate, and further covered with a silicone resin. The globe was made of a translucent polycarbonate having a visible light transmittance of 88% and having a dome shape with a thickness of about 1 mm. LED bulbs were each assembled using these components. The LED bulb thus obtained was subjected to the characteristic evaluation described later.

(Comparative Examples 1 to 5)
As shown in Table 3, the same phosphors as in Examples 1 to 5 were used, and these phosphors were mixed to form a phosphor film (a mixed phosphor layer having a single layer structure). An LED bulb was produced in the same manner. These LED bulbs were subjected to the characteristic evaluation described later.

(Comparative Example 6)
The LED bulb is manufactured in the same manner as in Example 1 except that a blue light emitting LED chip (emission peak wavelength: 450 nm) is used and a fluorescent film containing only a yellow phosphor (YAG phosphor) is formed on the inner surface of the globe. Produced. This was used for characteristic evaluation described later.

(Comparative Example 7)
A fluorescent lamp was prepared as a reference for the appearance color.

Next, for each of the LED bulbs of Examples 1 to 7 and Comparative Examples 1 to 6, and further for the fluorescent lamp of Comparative Example 7, the external color (L * a * b *) when not lit was spectrophotometer manufactured by Konica Minolta. Measured with CM 2500d. Each LED bulb was turned on, and the brightness of white light emitted from each LED bulb and the average color rendering index Ra were measured. These characteristics were measured by a SLMS total luminous flux measurement system manufactured by Loves Fair. Although the brightness of white light is at a practical level, the brightness was evaluated in three stages (◎, ○, Δ) for characteristic comparison.

As is apparent from Tables 2 to 3, it can be seen that the LED bulbs according to Examples 1 to 7 have a good appearance color when not lit. That is, when the chromaticity b * is compared between the example and the comparative example, the value of the example is smaller than that of the comparative example. In other words, it can be seen that the appearance color of the example is whiter when not lit. Even in the mixed phosphor layer having a single layer structure as in Comparative Examples 3 and 4, those having a low coloring level are close to the conventional fluorescent lamp (Comparative Example 7) by forming two layers as in Examples 3 and 4. The appearance color (white) can be improved. On the other hand, even if the mixed phosphor layer having a single-layer structure as in Comparative Example 5 is colored deeply, it can be improved to a light coloring level as shown in Examples 5 to 7. Moreover, it turns out that a coloring level is improved by 2 layers also about the comparative example of both middle. Further, it was confirmed that the LED bulbs according to the respective examples were excellent in the color rendering of white light and the glare was reduced.

(Examples 8 to 9)
Similar to Example 1 except that the phosphor combinations shown in Table 4 are applied and the first phosphor layer, the second phosphor layer, and the third phosphor layer are sequentially formed on the inner surface of the globe. Thus, an LED bulb was produced. The characteristics of these LED bulbs were measured and evaluated in the same manner as in Example 1. These measurement / evaluation results are shown in Table 4. Since Examples 8 to 9 use the same phosphor as Comparative Examples 2 and 4, Table 4 shows the measurement and evaluation results of Comparative Examples 2 and 4 together. Even when a phosphor layer having a three-layer structure is used, the coloring level of the appearance color can be improved.

In addition, although several embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

Claims

An LED module comprising a substrate and an ultraviolet or purple LED chip mounted on the substrate;
A base portion on which the LED module is installed;
A glove attached to the base so as to cover the LED module;
A fluorescent film that is provided inside the globe and spaced from the LED chip, and absorbs ultraviolet or violet light emitted from the LED chip to emit white light;
A lighting circuit provided in the base portion for lighting the LED chip;
Comprising a base electrically connected to the lighting circuit,
The phosphor film has two or more phosphor layers, and the first phosphor layer provided on the inner wall surface of the globe contains a phosphor having a white body color. LED bulb.
The LED bulb according to claim 1,
The phosphor contained in the first phosphor layer has a * of −35 or more and +15 or less, and b * of −10 or more and +30 when the body color is expressed in the L * a * b * color system. Hereinafter, an LED bulb characterized in that L * has a color of +40 or more.
The LED bulb according to claim 1,
The phosphor film has the first phosphor layer provided directly on the inner wall surface of the globe and a second phosphor layer provided on the first phosphor layer,
The first phosphor layer comprises europium activated alkaline earth chlorophosphate phosphor, europium and manganese activated alkaline earth aluminate phosphor, europium activated lanthanum oxysulfide phosphor, europium and bismuth activated oxidation. Containing a first phosphor composed of at least one selected from an yttrium phosphor and a manganese-activated magnesium fluorogermanate phosphor;
The second phosphor layer includes a second phosphor composed of one or more phosphors capable of obtaining white light emission in combination with the first phosphor. light bulb.
The LED bulb according to claim 1,
The LED bulb according to claim 1, wherein the phosphor film has a thickness in the range of 80 μm to 800 μm, and the first phosphor layer has a thickness of 40 μm or more.
The LED bulb according to claim 1,
The LED bulb according to claim 1, wherein the phosphor film includes a blue phosphor, a green to yellow phosphor, and a red phosphor.
The LED bulb according to claim 5,
The blue phosphor has the general formula: (Sr 1 -xyz Ba x Ca y Eu z ) 5 (PO 4 ) 3 Cl (1)
(Wherein x, y and z are numbers satisfying 0 ≦ x <0.5, 0 ≦ y <0.1, 0.005 ≦ z <0.1)
A europium-activated alkaline earth chlorophosphate phosphor having a composition represented by:
The green to yellow phosphor has the general formula: (Ba 1-xyz Sr x Ca y Eu z) (Mg 1-u Mn u) Al 10 O 17 ... (2)
(In the formula, x, y, z, and u satisfy 0 ≦ x <0.2, 0 ≦ y <0.1, 0.005 <z <0.5, and 0.1 <u <0.5. Is the number to do)
Europium and manganese activated alkaline earth aluminate phosphors having the composition represented by:
General formula: (Sr 1-xyzu Ba x Mg y Eu z Mn u) 2 SiO 4 ... (3)
(Wherein x, y, z and u are 0.1 ≦ x ≦ 0.35, 0.025 ≦ y ≦ 0.105, 0.025 ≦ z ≦ 0.25, 0.0005 ≦ u ≦ 0. 0.02)
Europium and manganese activated alkaline earth silicate phosphors having the composition represented by:
General formula: RE 3 A x Al 5- xy B y O 12: Ce z ... (4)
(In the formula, RE represents at least one element selected from Y, Lu, and Gd, A and B are paired elements, and (A, B) is (Mg, Si), (B, Sc), (B, In), and x, y, and z are x <2, y <2, 0.9 ≦ x / y ≦ 1.1, 0.05 ≦ z ≦ 0.5. Is a number that satisfies
A cerium-activated rare earth aluminate phosphor having a composition represented by:
General formula: (Si, Al) 6 (O, N) 8 : Eu x (5)
(Wherein x is a number satisfying 0 <x <0.3)
Europium activated sialon phosphor having a composition represented by the formula: (Sr 1-x Eu x ) α Si β Al γ O δ N ω (6)
(Where x, α, β, γ, δ, and ω are 0 <x <1, 0 <α ≦ 3, 12 ≦ β ≦ 14, 2 ≦ γ ≦ 3.5, 1 ≦ δ ≦ 3, 20 ≦ ω ≦ 22)
Is at least one selected from europium activated sialon phosphors having a composition represented by:
The red phosphor has the general formula: (La 1-xy Eu x M y) 2 O 2 S ... (7)
(In the formula, M represents at least one element selected from Sm, Ga, Sb, and Sn, and x and y satisfy 0.08 ≦ x <0.16 and 0.000001 ≦ y <0.003. Is the number to do)
A europium-activated lanthanum oxysulfide phosphor having a composition represented by:
General formula: (Y 1-xy Eu x Bi y ) 2 O 3 (8)
(Wherein x and y are numbers satisfying 0.01 ≦ x <0.15 and 0.001 ≦ y <0.05)
Europium and bismuth activated yttrium oxide phosphors having a composition represented by:
General formula: (Ca 1-xy Sr x Eu y ) SiAlN 3 (9)
(Wherein x and y are numbers satisfying 0 ≦ x <0.4 and 0 <y <0.5)
And a europium-activated couun phosphor having a composition represented by the general formula: (Sr 1-x Eu x ) α Si β Al γ O δ N ω (10)
(Where x, α, β, γ, δ, and ω are 0 <x <1, 0 <α ≦ 3, 5 ≦ β ≦ 9, 1 ≦ γ ≦ 5, 0.5 ≦ δ ≦ 2, 5 ≦ ω ≦ 15)
An LED bulb characterized by being at least one selected from europium-activated sialon phosphors having a composition represented by:
The LED bulb according to claim 6,
The phosphor film has the first phosphor layer provided directly on the inner wall surface of the globe and a second phosphor layer provided on the first phosphor layer,
The first phosphor layer contains the europium activated alkaline earth chlorophosphate phosphor as the blue phosphor,
The LED light bulb characterized in that the second phosphor layer contains the green to yellow phosphor and the red phosphor.
The LED bulb according to claim 6,
The phosphor film has the first phosphor layer provided directly on the inner wall surface of the globe and a second phosphor layer provided on the first phosphor layer,
The first phosphor layer contains the europium and bismuth activated yttrium oxide phosphor as the red phosphor,
The LED light bulb characterized in that the second phosphor layer contains the blue phosphor and the green to yellow phosphor.
The LED bulb according to claim 5,
The phosphor film comprises 10% by mass to 60% by mass of the blue phosphor, 1% by mass to 30% by mass of the green to yellow phosphor, and 30% by mass to 90% by mass of the red phosphor. An LED bulb comprising a mixed phosphor that is contained so that the total amount of each phosphor is 100% by mass.
The LED bulb according to claim 5,
The LED bulb according to claim 1, wherein the phosphor film further includes at least one phosphor selected from a blue-green phosphor and a deep red phosphor.
The LED bulb according to claim 10,
The blue-green phosphor has the general formula: (Ba 1-xyzu Sr x Mg y Eu z Mn u) 2 SiO 4 ... (11)
(Wherein x, y, z and u are 0.1 ≦ x ≦ 0.35, 0.025 ≦ y ≦ 0.105, 0.025 ≦ z ≦ 0.25, 0.0005 ≦ u ≦ 0. 0.02)
Europium and manganese activated alkaline earth silicate phosphors having the composition represented by:
The deep red phosphor is represented by the general formula: αMgO · βMgF 2. (Ge 1-x Mn x ) O 2 (12)
(In the formula, α, β, and x are numbers satisfying 3 ≦ α ≦ 4, 0.4 ≦ β ≦ 0.6, and 0.001 ≦ x ≦ 0.5)
An LED bulb characterized by being a manganese-activated magnesium fluorogermanate phosphor having a composition represented by:
The LED bulb according to claim 11,
The phosphor film has the first phosphor layer provided directly on the inner wall surface of the globe and a second phosphor layer provided on the first phosphor layer,
The first phosphor layer contains the manganese-activated magnesium fluorogermanate phosphor as the deep red phosphor,
The LED phosphor, wherein the second phosphor layer contains the blue phosphor, the green to yellow phosphor, and the red phosphor.
The LED bulb according to claim 10,
The phosphor film includes 10% by mass to 60% by mass of the blue phosphor, 0% by mass to 10% by mass of the blue-green phosphor, 1% by mass to 30% by mass of the green to yellow phosphor, Mixed fluorescence containing 30% by mass or more and 90% by mass or less of the red phosphor and 0% by mass or more and 35% by mass or less of the deep red phosphor so that the total amount of each phosphor is 100% by mass. An LED bulb characterized by including a body.
The LED bulb according to claim 1,
2. The LED bulb according to claim 1, wherein the globe has a transparent or white body color and is made of a material having a visible light transmittance of 90% or more.
The LED bulb according to claim 1,
The LED bulb is characterized in that ultraviolet to violet emission emitted from the LED chip has an emission peak wavelength in a range of 370 nm to 415 nm and a full width at half maximum of an emission spectrum of 10 nm to 15 nm.
The LED bulb according to claim 1,
The white light emitted from the fluorescent film has an correlated color temperature of 6500K or less and an average color rendering index Ra of 85 or more.
The LED bulb according to claim 1,
The LED module includes: a plurality of the LED chips surface-mounted on the substrate; and a transparent resin layer provided on the substrate so as to cover the plurality of LED chips. .
The LED bulb according to claim 1,
The globe has an LED bulb having a dome shape or an eggplant shape.