LED ASSEMBLY WITH COLOR TEMPERATURE CORRECTION CAPABILITY
An illumination assembly is provided which is capable of correcting a color temperature. The assembly generally comprises a substrate and a light emitting device mounted on the substrate that further comprises a light emitting element and a resin containing a phosphor excitable by light emitted from the light emitting element. A reflectance factor of the substrate may be set corresponding to light emitted from the light emitting device, such that the light emitted by the light emitting device complies with a desired light emission for the illumination assembly. A translucent filling resin or translucent coating resin may further be applied on the light emitting device and the substrate, the translucent resin having a refractive index and correspondingly operable to suppress variations in color temperature. The assembly may comprise a plurality of light emitting devices having variable light color temperatures, wherein a plurality of substrate coatings may be provided having reflectance factors corresponding to the associated light color temperatures. One or more translucent resins may be applied on light emitting devices as desired to further suppress variations in color temperature.
A portion of the disclosure of this patent document contains material that is subject to copyright protection. The copyright owner has no objection to the reproduction of the patent document or the patent disclosure, as it appears in the U.S. Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever.
CROSS-REFERENCES TO RELATED APPLICATIONSThis application claims benefit of the following patent application which is hereby incorporated by reference: Japanese Patent Application No. JP2008-113315 filed Apr. 24, 2008
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENTNot Applicable
REFERENCE TO SEQUENCE LISTING OR COMPUTER PROGRAM LISTING APPENDIXNot Applicable
BACKGROUND OF THE INVENTIONThe present invention relates to an illumination device using a light emitting element such as a light emitting diode (hereinafter referred to as “LED”).
In a conventional illumination device using a light emitting element such as an LED, countermeasures are taken to make it waterproof in consideration of the outdoor installation. At least one waterproofing technique has previously been employed in which a case is filled with a transparent resin.
For example, Japanese Unexamined Patent Publication No. 2005-302483 discloses an illumination device providing: a substrate with an LED mounted thereon; and a transparent and nearly box-shaped case with a back surface formed as an opening, wherein: the substrate is stored in the case from the opening; the substrate is supported with a space provided between the substrate and a front inner wall of the case; a transparent filling material is injected and filled in the case along a following path from the opening to the case; the filling material is cured to fix the substrate and the case integrally; and thus the LED along with the substrate are embedded in the filling material in the case and hermetically sealed, thereby ensuring a sufficient waterproof property. When the LED is lighted, the light is emitted through the transparent filling material and the case.
BRIEF SUMMARY OF THE INVENTIONA white or blue-colored LED used for the purpose of the illumination typically has a structure in which an LED chip that emits blue light (light with wavelength of approximately 380 to 480 nm) is sealed with a resin containing a phosphor (e.g., silicon, epoxy). The conversion to a desired color of light is performed by means of the light with a wavelength region of approximately 480 to 780 nm that is converted by exciting the phosphor by the blue light emitted from the LED chip, and blue light that passes through the resin without being converted. Also, in the conversion to a desired color of light, the color of light is adjusted by, for example, changing a mixing ratio of the phosphor in the case where a top surface of the sealing resin containing the phosphor is an air layer. It is not premised on filling the top surface of the sealing resin containing the phosphor with the transparent resin (e.g., silicon).
When the case that stores the LED is filled with translucent silicon for the purpose of waterproofing, a refractive index of the sealing resin for the LED is almost equal to that of the silicon to be filled for the purpose of waterproofing. Therefore, there is a problem that the color temperature significantly shifts to a side of high color temperature due to a difference of the ratio between the light converted by exciting the phosphor by the blue light emitted from the LED chip, and the blue light that passes through without being converted, as compared to the case where the top surface of the sealing resin containing the phosphor is the air layer. An increase of the ratio of the blue light makes a white LED appear to be bluish white, and a bulb-colored LED appear to be yellowish white.
In view of the foregoing, an object of the present invention is to provide an illumination device capable of correcting the color temperature. In light of this object, an LED assembly with color correcting substrate in various embodiments may comprise one or more of the following aspects.
According to a first aspect of the LED assembly with color correcting substrate herein disclosed, in order to solve the problems described above, an illumination device as shown in
In a second aspect of the LED assembly, the LED assembly is provided with the light emitting device (the LED 1), the substrate 2, and a case 3 for storing the resin 4 applied on the light emitting device (the LED 1) and the substrate 2.
In a third aspect of the LED assembly, the setting of the reflectance factor of the substrate 2 is to set the color of the substrate surface so as to suppress the change of the color temperature before and after applying the transparent resin 4.
In a fourth aspect of the LED assembly, an LED chip 5 is used as the light emitting element.
In a fifth aspect of the LED assembly, a plurality of LED chips is included.
In a sixth aspect of the LED assembly, each of the plurality of LED chips falls into various types having a different light spectra from each other.
In a seventh aspect of the LED assembly, the light emitting device uses an LED chip 5 emitting blue light with wavelength of approximately 380 to 480 nm, a phosphor emits light with a wavelength region of approximately 480 to 780 nm by being excited by the blue light; and the color of the substrate surface is color absorbing the blue light.
In an eighth aspect of the LED assembly, a coating 8 having the color absorbing the blue light is applied on the substrate surface, as shown in
In a ninth aspect of the LED assembly, the transparent resin 4 to be applied on the light emitting device and the substrate 2 contains a pigment 9 absorbing light with a specified wavelength, as shown in
In a tenth aspect of the LED assembly, the transparent resin 4 to be applied on the light emitting device and the substrate 2 contains a phosphor 10 exciting light with a specified wavelength, as shown in
In an eleventh aspect of the LED assembly, a plurality of light emitting devices (LEDs 1) is included, as shown in
In a twelfth aspect of the LED assembly, the color temperature is set lower for the substrate surface provided the light emitting device mounted thereon with higher color temperature, upon the plurality of light emitting devices 1a, 1b and 1c having the different color temperatures from one another (
In a thirteenth aspect of the LED assembly, the resin having a lower refractive index is applied to the light emitting device with higher color temperature, and to the periphery of the substrate providing such light emitting device mounted thereon, upon the plurality of light emitting devices having the different color temperatures from one another (
In a fourteenth aspect of the LED assembly, the inside of the case 3 is completely filled with the translucent resin 4 applied on the light emitting device (the LED 1) and the substrate 2.
In a fifteenth aspect of the LED assembly, the color temperature of the light emitted from the light emitting device is set to be lower than the color temperature required for the illumination device.
In an illumination device according to a preferred embodiment of the disclosed LED assembly, a light emitting device in which a light emitting device is sealed with a resin containing a phosphor is mounted on a substrate, and a translucent resin is applied to the light emitting device and the substrate. A reflectance factor of the substrate is set corresponding to the light emitted from the light emitting device, so that the color temperature can be readily corrected at low cost by changing the reflectance factor of the substrate even if the emission color deviates from the desired color temperature due to the relationship between a refractive index of a resin sealing the light emitting element and that of a resin containing the sealing resin which fills the light emitting device and the substrate.
The LED 1 comprising the light emitting device may be provided with a blue LED chip 5 which emits light with a wavelength of approximately 380 to 480 nm, the blue LED chip sealed with a resin 6 (e.g., silicon) containing a phosphor. One sealing resin 6 may encompass a plurality of LED chips 5.
The substrate 2 on which the LED 1 is mounted comprises a base material 7, and a coating (ink) 8 applied on the base material 7. The LED 1 and the substrate 2 are embedded and hermetically sealed in the resin 4. The case 3 is transparent, so that, upon lighting the LED 1, the light therefrom is emitted through the translucent resin 4 and the case 3.
Conventionally, a white coating (ink) has been generally used as the coating (ink) 8 to apply on the base material 7, in consideration of a reflection efficiency for reflecting light reflected by the case 3 and an air layer at the surface of the substrate 2 to emit the light to the outside of the case 3; whereas a yellow coating (ink) is applied in the present embodiment.
Thus, the substrate surface reflects only light within a high luminosity region (yellow light) and absorbs the blue light among the light reflected by the case 3 and the air layer. This can reduce the shift of the color temperature to a higher color temperature, without decreasing an optical output.
In alternative embodiments, the same effect as those described above can be achieved by applying on the substrate surface a substance such as a film 8 which reflects the light within a high luminosity region and absorbs the blue light, instead of coating the base material 7 with the ink 8. Such effect also can be achieved by employing a translucent material other than a resin as the resin 4 for filling the case 3.
In another embodiment as shown in
In another embodiment as shown in
In an embodiment as shown in
In an embodiment as shown in
The translucent filling material 4 may in certain embodiments comprise both of the phosphor 10 and the pigment 9 in conjunction with each other. An adjustment of the mixing ratio between the phosphor 10 and the pigment 9 within the translucent filling material 4 or resin 4 further enables the color temperature to be adjusted.
In an embodiment of the LED assembly as shown in
The inner space of the case 3 is filled with the translucent filling resins (for example, silicon) 4a, 4b and 4c within the respective portions where a plurality of LEDs 1a, 1b and 1c are mounted. The presetting is now made so as to be (a refractive index of the resin 4a)>(a refractive index of the resin 4b)>(a refractive index of the resin 4c).
When the filling is performed onto the LEDs 1a, 1b and 1c with the translucent filling resins 4a, 4b and 4c, the emission colors thereof shift to blue. The shift to blue, however, can be reduced by means of the yellow coatings (ink) 8a, 8b and 8c.
The presetting is now made so as to be (a color temperature of the yellow coating 8a)<(a color temperature of the yellow coating 8b)<(a color temperature of the yellow coating 8c). The higher the color temperatures of the yellow coatings (ink) 8a, 8b and 8c become, the more the substrate 2 absorbs the blue light, thereby reducing the shift to blue. Also, the lower the refractive indices of the translucent filling resins 4a, 4b and 4c become (the nearer the refractive index of the air become), the more the shift to blue is reduced.
Therefore, as shown in the present embodiment, even if the LEDs 1a, 1b and 1c emit light having varying color temperatures from one another, the variation of the color temperatures in the illumination device can be suppressed by adjusting the color temperatures of the yellow coatings (ink) 8a, 8b and 8c applied on the base material 7, as well as the refractive indices of the translucent filling resins 4a, 4b and 4c.
As described above, adjustment of the coloration of the coatings applied on the LED mounting substrate and the refractive indices of the filling resins can suppress the variation of the color temperatures in the illumination device with greater reliability and less cost than alternative methods.
In this case, the coatings (ink) 8a and 8c on the periphery of the LEDs 1a and 1c at both ends of the substrate are the ones having lower reflectance factors to the blue light, such as yellow. In contrast, the coating (ink) 8b on the periphery of the LED 1b in the middle of the substrate is the one having a higher reflectance factor to the blue light, such as white or blue. This structure also includes a coating material 4b (such as silicon) being applied on the substrate surface (the coating 8b) on the periphery of the LED 1b in the middle of the substrate.
Here, when the filling is performed onto the LED 1b with a translucent filling material 4b or translucent coating material 4b such as a translucent resin 4b, the emission color thereof shifts to blue. Furthermore, since the coating (ink) 8b with a higher reflectance factor to the blue light increases the reflection of the blue light, the light coming from the coating material 4b can be shifted to blue. This enables the color temperature thereof to shift to the higher temperature, thereby making it possible to be brought closer to the color temperatures of the LEDs 1a and 1c on both ends of the substrate.
Changing the coloration of the coatings on the mounting substrate for the LEDs and coating a part of LEDs with the filling resin can suppress the variation of the color temperatures in the illumination device, even if employing the LEDs with the color temperatures different from one another in the illumination device that requires no filling resin.
Still referring to
Table 1 shows the result of the measurement of the optical characteristics before and after the filling, and Table 2 shows the amount of change before and after the filling of the silicon.
In the case of the white LED, when the color temperature of 5000K is required for the illumination device and the color temperature of an output flux of the LED 1 is 5000K, employing a waterproof structure as shown in
In the case of the bulb-colored LED, when the color temperature of 2800K is required for the illumination device and the color temperature of an output flux of the LED 1 is 2800K, employing the waterproof structure as shown in
By use of embodiments described above, the color temperature can be corrected as desired and necessary for the illumination device.
Thus, although there have been described particular embodiments of the present invention of a new and useful LED Assembly with Color Correcting Substrate it is not intended that such references be construed as limitations upon the scope of this invention except as set forth in the following claims.
Claims
1. An illumination assembly, comprising:
- a substrate;
- a light emitting device mounted on the substrate, the light emitting device further comprising a light emitting element, and a resin containing a phosphor excitable by light emitted from the light emitting element; and
- a reflectance factor of the substrate set corresponding to light emitted from the light emitting device.
2. The illumination assembly of claim 1, wherein the substrate further comprises:
- a base material; and
- a coating having color absorbing a particular spectrum of light emitted from the light emitting device,
- wherein variations of a color temperature are suppressed.
3. The illumination assembly of claim 2, wherein the light emitting element further comprises an LED chip emitting blue light with a wavelength of approximately 380 to 480 nm, and a phosphor emitting light with a wavelength of approximately 480 to 780 nm by being excited by the blue light; and
- wherein the color of the substrate coating is operable to absorb the blue light.
4. The illumination assembly of claim 1, further comprising a translucent resin applied on the light emitting device and the substrate, the translucent resin having a refractive index and correspondingly effective to suppress variations in color temperature.
5. The illumination assembly of claim 4, further comprising a transparent case encompassing the light emitting device, the substrate and the translucent resin applied on the light emitting device and the substrate.
6. The illumination assembly of claim 5, wherein the inside of the case is completely filled with the translucent resin applied on the light emitting device and the substrate.
7. The illumination assembly of claim 4, the translucent resin applied on the light emitting device and the substrate further comprises a pigment absorbing light with a specified wavelength region.
8. The illumination assembly of claim 4, wherein the transparent resin applied on the light emitting device and the substrate further comprises a phosphor exciting light with a specified wavelength region.
9. The illumination assembly of claim 4, wherein the translucent resin applied on the light emitting device and the substrate further comprises both of a pigment absorbing light with a specified wavelength region and a phosphor exciting light with a specified wavelength region, wherein a mixing ratio between the amounts of pigment and phosphor may be adjusted to produce a desired refractive index for the translucent resin.
10. An illuminating assembly the assembly comprising:
- a plurality of light emitting devices, each light emitting device further comprising a light emitting element, and a resin containing a phosphor excitable by light emitted from the light emitting element;
- a substrate on which the plurality of light emitting devices are mounted, the substrate further comprising a base material, and a plurality of coatings, each coating associated with one of the plurality of light emitting elements; and
- a color temperature of each substrate coating set corresponding to light emitted from the associated light emitting device.
11. The assembly of claim 10, the plurality of light emitting elements further comprising a plurality of blue LED chips functional to emit light having a wavelength of approximately 380 to 480 nm, each blue LED chip further sealed with the resin containing a phosphor excitable by the light emitted from the associated blue LED chip.
12. The assembly of claim 11, the plurality of coatings further comprising yellow ink coatings of variable color temperatures, wherein setting higher substrate coating color temperatures corresponds with increasing absorption of blue light emitted from the associated light emitting devices.
13. The assembly of claim 11, further comprising:
- a transparent case containing the plurality of light emitting devices and the substrate, and
- a plurality of translucent resins filling the inner space of the case, a translucent resin associated with each of the plurality of light emitting devices,
- each translucent resin having a refractive index set corresponding to light emitted from the associated light emitting device.
14. The assembly of claim 13, wherein setting lower refractive indices corresponds with increasing absorption of blue light emitted from the associated light emitting devices.
15. An illuminating assembly for suppressing variation of color temperatures in the assembly, the assembly comprising:
- a plurality of light emitting devices, each light emitting device further comprising a light emitting element, and a resin further comprising phosphor excitable by light emitted from the light emitting element, a compounding ratio of the phosphor corresponding to a color temperature of the light emitted by the light emitting element;
- a substrate on which the plurality of light emitting devices are mounted, the substrate further comprising a plurality of coatings associated with the plurality of light emitting elements mounted thereon; and
- one or more translucent coating resins applied to one or more light emitting devices, a refractive index for each translucent coating resin set corresponding to the light emitted from the corresponding light emitting device.
16. The assembly of claim 15, wherein one or more light emitting devices are not coated with a translucent coating resin.
17. The assembly of claim 15, further comprising a color temperature of each substrate coating set corresponding to light emitted from the associated light emitting device.
18. The assembly of claim 17, wherein the one or more translucent coating resins may be applied after setting a color temperature for each substrate coating, wherein variation of color temperatures of light emitted by the plurality of light emitting devices is suppressed.
19. The assembly of claim 15, wherein a color temperature of the light emitted from each of the plurality of light emitting devices is set to be lower than the color temperature required for the illumination device.
20. The assembly of claim 19, wherein each light emitting device further comprises a resin further comprising phosphor excitable by light emitted from the light emitting element,
- wherein a compounding ratio of the phosphor corresponds to a color temperature of the light emitted by the light emitting element, the compounding ratio adjustable to set the color temperature of the light emitted from each of the plurality of light emitting devices to be lower than the color temperature required for the illumination device.
Type: Application
Filed: Apr 24, 2009
Publication Date: Jan 7, 2010
Inventors: Jun Takashima (Osaka), Norio Kanai (Osaka)
Application Number: 12/429,787
International Classification: H01L 27/15 (20060101); H01L 33/00 (20060101);