Patent Application
20050274972
1. Field of the Invention
The invention relates to light emitting devices and more particularly to light emitting devices including at least one light-emitting diode and phosphor, the phosphor including lead and/or copper doped chemical compounds and converting the wavelength of light.
2. Description of the Related Art
Light emitting devices (LEDs), which used to be used for electronic devices, are now used for automobiles and illumination products. Since light emitting devices have superior electrical and mechanical characteristics, demands for light emitting devices have been increased. In connection to this, interests in white LEDs are increasing as an alternative to fluorescent lamps and incandescent lamps.
In LED technology, solution for realization of white light is proposed variously. Normally, realization of white LED technology is to put the phosphor on the light-emitting diode, and mix the primary emission from the light emitting diode and the secondary emission from the phosphor, which converts the wavelength. For example, as shown in WO 98/05078 and WO 98/12757, use a blue light emitting diode, which is capable of emitting a peak wavelength at 450-490 nm, and YAG group material, which absorbs light from the blue light emitting diode and emits yellowish light (mostly), which may have different wavelength from that of the absorbed light.
However, in such a usual white LED, color temperature range is narrow which is between about 6,000-8,000K, and CRI (Color Rendering Index) is about 60 to 75. Therefore, it is hard to produce the white LED with color coordination and color temperature that are similar to those of the visible light. It is one of the reasons why only white light color with a cold feeling could be realized. Moreover, phosphors which are used for white LEDs are usually unstable in the water, vapor or polar solvent, and this unstableness may cause changes in the emitting characteristics of white LED.
Wavelength conversion light emitting device are provided. In one embodiment consistent with this invention, a device is provided for emitting light. The device can include a substrate, a plurality of electrodes provided on the substrate, a light emitting diode configured to emit light, the light emitting diode being provided on one of the plurality of electrodes, phosphors configured to change a wavelength of the light, the phosphors substantially covering at least a portion of the light emitting diode, and an electrically conductive device configured to connect the light emitting diode with another of the plurality of electrodes.
In another embodiment consistent with this invention, a light emitting device can include a plurality of leads, a diode holder provided at the end of one of the plurality of lead, a light emitting diode provided in the diode holder, the light emitting diode including a plurality of electrodes, phosphors configured to change a wavelength of the light, the phosphors substantially covering at least a portion of the light emitting diode; and an electrically conductive device configured to connect the light emitting device with another of the plurality of leads.
In another embodiment consistent with this invention, a light emitting device may include a housing, a heat sink at least partially provided in the housing, a plurality of lead frames provided on the heat sink, a light emitting diode mounted on one of the plurality of lead frames, phosphors configured to change a wavelength of the light, the phosphors substantially covering at least a portion of the light emitting diode, and an electrically conductive device configured to connect the light emitting diode with another of the plurality of lead frames.
The phosphor in consistent with this invention may include aluminate type compounds, lead and/or copper doped silicates, lead and/or copper doped antimonates, lead and/or copper doped germanates, lead and/or copper doped germanate-silicates, lead and/or copper doped phosphates, or any combination thereof. Formulas for phosphors consistent with this invention are also provided.
Further aspects of the invention may be apparent upon consideration of the following detailed description, taken in conjunction with the accompanying drawings, in which like reference characters refer to like parts throughout, and in which:
Refer to the attached drawing, the wavelength conversion light emitting device is going to be explained in detail, and the light emitting device and the phosphor are separately explained for easiness of explanation as below.
(Light Emitting Device)
Light emitting diodes may emit light with a wide range of wavelengths, for example, from ultraviolet light to visible light. In one embodiment consistent with this invention, a UV light emitting diode and/or blue light emitting diode may be use.
Phosphor, i.e., a phosphorescent substance, 3 may be placed on the top and side faces of the light emitting diode 6. The phosphor in consistent with this invention may include lead and/or copper doped aluminate type compounds, lead and/or copper doped silicates, lead and/or copper doped antimonates, lead and/or copper doped germanates, lead and/or copper doped germanate-silicates, lead and/or copper doped phosphates, or any combination thereof. Phosphor 3 converts the wavelength of the light from the light emitting diode 6 to another wavelength or other wavelengths. In one embodiment consistent with this invention, the light is in a visible light range after the conversion. Phosphor 3 may be applied to light emitting diode 6 after mixing phosphor 3 with a hardening resin. The hardening resin including phosphor 3 may also be applied to the bottom of light emitting diode 6 after mixing phosphor 3 with electrically conductive paste 9.
The light emitting diode 6 mounted on substrate 1 may be sealed with one or more sealing materials 10. Phosphor 3 may be placed on the top and side faces of light emitting diode 6. Phosphor 3 can also be distributed in the hardened sealing material during the production. Such a manufacturing method is described in U.S. Pat. No. 6,482,664, which is hereby incorporated by reference in its entirety.
Phosphor 3 may comprise lead and/or copper doped chemical compound(s). Phosphor 3 may include one or more single chemical compounds. The single compound may have an emission peak of, for example, from about 440 nm to about 500 nm, from about 500 nm to about 590 nm, or from about 580 nm to 700 nm. Phosphor 3 may include one or more single phosphors, which may have an emission peak as exemplified above.
In regard to light emitting device 40, light emitting diode 6 may emit primary light when light emitting diode 6 receives power from a power supply. The primary light then may stimulate phosphor(s) 3, and phosphor(s) 3 may convert the primary light to a light with longer wavelength(s) (a secondary light). The primary light from the light emitting diode 6 and the secondary light from the phosphors 3 are diffused and mixed together so that a predetermined color of light in visible spectrum may be emitted from light emitting diode 6. In one embodiment consistent with this invention, more than one light emitting diodes that have different emission peaks can be mounted together. Moreover, if the mixture ratio of phosphors is adjusted properly, specific color of light, color temperature, and CRI can be provided.
As described above, if the light emitting diode 6 and the compound included in phosphor 3 are properly controlled then desired color temperature or specific color coordination can be provided, especially, wide range of color temperature, for example, from about 2,000K to about 8,000K or about 10,000K and/or color rendering index of greater than about 90. Therefore, the light emitting devices consistent with this invention may be used for electronic devices such as home appliances, stereos, telecommunication devices, and for interior/exterior custom displays. The light emitting devices consistent with this invention may also be used for automobiles and illumination products because they provide similar color temperatures and CRI to those of the visible light.
In top-type package light emitting device 50, more than one light emitting diodes can be mounted. Each of such light emitting diodes may have a different peak wavelength from that of others. Phosphor 3 may comprise a plurality of single compounds with different emission peak. The proportion of each of such plurality of compounds may be regulated. Such a phosphor may be applied to the light emitting diode and/or uniformly distributed in the hardening material of the reflector 31. As explained more fully below, the phosphor in consistent with this invention may include lead and/or copper doped aluminate type compounds, lead and/or copper doped silicates, lead and/or copper doped antimonates, lead and/or copper doped germanates, lead and/or copper doped germanate-silicates, lead and/or copper doped phosphates, or any combination thereof.
In one embodiment consistent with this invention, the light emitting device of the
Regular volume of phosphor 3, which may be mixed in the epoxy resin, may be provided in diode holder 53. As explained more fully below, phosphor 3 may include lead and/or copper doped components.
Moreover, the diode holder may include the light emitting diode 6 and the phosphor 3 may be sealed with hardening material such as epoxy resin or silicon resin.
In one embodiment consistent with this invention, the lamp type package light emitting device may have more than one pair of electrode pair leads.
One or more light emitting diodes may be mounted one lead frame 74, and an electrode of the light emitting diode 6 and another lead frame 74 may be connected via electrically conductive wire. Electrically conductive pate 9 may be provided between light emitting diode 6 and lead frame 74. The phosphor 3 may be placed on top and side faces of light emitting diode 6.
Light emitting device for high power 80 may have housing 63, which may contain light emitting diodes 6, 7, phosphor 3 arranged on the top and side faces of light emitting diodes 6, 7, one or more heat sinks 61, 62, and one or more lead frames 64. The lead frames 64 may receive power from a power supplier and may protrude from housing 63.
In the light emitting devices for high power 70, 80 in the
In a light emitting device for high power consistent with this invention, one or more light emitting diodes can be used selectively and the phosphor can be regulated depending on the light emitting diode. As explained more fully below, the phosphor may include lead and/or copper doped components.
A light emitting device for high power consistent with this invention may have a radiator (not shown) and/or heat sink(s). Air or a fan may be used to cool the radiator.
The light emitting devices consistent with this invention is not limited to the structures described above, and the structures can be modified depending on the characteristics of light emitting diodes, phosphor, wavelength of light, and also applications. Moreover, new part can be added to the structures.
An exemplary phosphor consistent with this invention is as follows.
(Phosphor)
Phosphor in consistence with this invention may include lead and/or copper doped chemical compounds. The phosphor may be excited by UV and/or visible light, for example, blue light. The compound may include Aluminate, Silicate, Antimonate, Germanate, Germanate-silicate, or Phosphate type compounds.
Aluminate type compounds may comprise compounds having formula (1), (2), and/or (5)
a(M′O).b(M″2O).c(M″X).dAl2O3.e(M′″O).f(M″″2O3).g(M′″″oOp).h(M″″″xOy) (1)
The preparation of copper as well as lead doped luminescent materials may be a basic solid state reaction. Pure starting materials without any impurities, e.g. iron, may be used. Any starting material which may transfer into oxides via a heating process may be used to form oxygen dominated phosphors.
Examples of Preparation:
Preparation of the Luminescent Material Having Formula (3)
Cu0.02Sr3.98Al14O25:Eu (3)
Starting materials: CuO, SrCO3, Al(OH)3, Eu2O3, and/or any combination thereof.
The starting materials in the form of oxides, hydroxides, and/or carbonates may be mixed in stoichiometric proportions together with small amounts of flux, e.g., H3BO3. The mixture may be fired in an alumina crucible in a first step at about 1,200° C. for about one hour. After milling the pre-fired materials a second firing step at about 1,450° C. in a reduced atmosphere for about 4 hours may be followed. After that the material may be milled, washed, dried and sieved. The resulting luminescent material may have an emission maximum of about 494 nm.
Preparation of the Luminescent Material Having Formula (4)
Pb0.05Sr3.95Al14O25:Eu (4)
Starting materials: PbO, SrCO3, Al2O3, Eu2O3, and/or any combination thereof.
The starting materials in form of very pure oxides, carbonates, or other components which may decompose thermically into oxides, may be mixed in stoichiometric proportion together with small amounts of flux, for example, H3BO3. The mixture may be fired in an alumina crucible at about 1,200° C. for about one hour in the air. After milling the pre-fired materials a second firing step at about 1,450° C. in air for about 2 hours and in a reduced atmosphere for about 2 hours may be followed. Then the material may be milled, washed, dried, and sieved. The resulting luminescent material may have an emission maximum of from about 494.5 nm.
Example of Preparation:
Preparation of the Luminescent Material Having Formula (6)
Cu0.05Sr0.95Al1.9997Si0.0003O4:Eu (6)
Starting materials: CuO, SrCO3, Al2O3, SiO2, Eu2O3, and/or any combination thereof.
The starting materials in the form of, for example, pure oxides and/or as carbonates may be mixed in stoichiometric proportions together with small amounts of flux, for example, AlF3. The mixture may be fired in an alumina crucible at about 1,250° C. in a reduced atmosphere for about 3 hours. After that the material may be milled, washed, dried and sieved. The resulting luminescent material may have an emission maximum of about 521.5 nm.
Preparation of the Luminescent Material Having Formula (7)
Cu0.12BaMg1.88Al16O27:Eu (7)
Starting materials: CuO, MgO, BaCO3, Al(OH)3, Eu2O3, and/or any combination thereof.
The starting materials in the form of, for example, pure oxides, hydroxides, and/or carbonates may be mixed in stoichiometric proportions together with small amounts of flux, for example, AlF3. The mixture may be fired in an alumina crucible at about 1,420° C. in a reduced atmosphere for about 2 hours. After that the material may be milled, washed, dried, and sieved. The resulting luminescent material may have an emission maximum of about 452 nm.
Preparation of the Luminescent Material Having Formula (8)
Pb0.1Sr0.9Al2O4:Eu (8)
Starting materials: PbO, SrCO3, Al(OH)3, Eu2O3, and/or any combination thereof.
The starting materials in form of, for example, pure oxides, hydroxides, and/or carbonates may be mixed in stochiometric proportions together with small amounts of flux, for example, H3BO3. The mixture may be fired in an alumina crucible at about 1,000° C. for about 2 hours in the air. After milling the pre-fired materials a second firing step at about 1,420° C. in the air for about 1 hour and in a reduced atmosphere for about 2 hours may be followed. After that the material may be milled, washed, dried and sieved. The resulting luminescent material may have an emission maximum of about 521 nm.
Results obtained in regard to copper and/or lead doped aluminates are shown in table 7.
A lead and/or copper doped silicates having formula (9)
a(M′O).b(M″O).c(M′″X).d(M′″2O).e(M″″2O3).f(M′″″oOp).g(SiO2).h(M″″″xOy) (9)
Example of Preparation:
Preparation of the Luminescent Material Having Formula (10)
Cu0.05Sr1.7Ca0.25SiO4:Eu (10)
Starting materials: CuO, SrCO3, CaCO3, SiO2, Eu2O3, and/or any combination thereof.
The starting materials in the form of pure oxides and/or carbonates may be mixed in stoichiometric proportions together with small amounts of flux, for example, NH4Cl. The mixture may be fired in an alumina crucible at about 1,200° C. in an inert gas atmosphere (e.g., N2 or noble gas) for about 2 hours. Then the material may be milled. After that, the material may be fired in an alumina crucible at about 1,200° C. in a slightly reduced atmosphere for about 2 hours. Then, the material may be milled, washed, dried, and sieved. The resulting luminescent material may have an emission maximum at about 592 nm.
Preparation of the Luminescent Material Having Formula (11):
Cu0.2Ba2Zn0.2Mg0.6Si2O7:Eu (1)
Starting materials: CuO, BaCO3, ZnO, MgO, SiO2, Eu2O3, and/or any combination thereof.
The starting materials in the form of very pure oxides and carbonates may be mixed in stoichiometric proportions together with small amounts of flux, for example, NH4Cl. In a first step the mixture may be fired in an alumina crucible at about 1,100° C. in a reduced atmosphere for about 2 hours. Then the material may be milled. After that the material may be fired in an alumina crucible at about 1,235° C. in a reduced atmosphere for about 2 hours. Then that the material may be milled, washed, dried and sieved. The resulting luminescent material may have an emission maximum at about 467 nm.
Preparation of the Luminescent Material Having Formula (12)
Pb0.1Ba0.95Sr0.95Si0.998Ge0.002O4:Eu (12)
Starting materials: PbO, SrCO3, BaCO3, SiO2, GeO2, Eu2O3, and/or any combination thereof.
The starting materials in the form of oxides and/or carbonates may be mixed in stoichiometric proportions together with small amounts of flux, for example, NH4Cl. The mixture may be fired in an alumina crucible at about 1,000° C. for about 2 hours in the air. After milling the pre-fired materials a second firing step at 1,220° C. in air for 4 hours and in reducing atmosphere for 2 hours may be followed. After that the material may be milled, washed, dried and sieved. The resulting luminescent material may have an emission maximum at about 527 nm.
Preparation of the Luminescent Material Having Formula (13)
Pb0.25Sr3.75Si3O8Cl4:Eu (13)
Starting materials: PbO, SrCO3, SrCl2, SiO2, Eu2O3, and any combination thereof.
The starting materials in the form of oxides, chlorides, and/or carbonates may be mixed in stoichiometric proportions together with small amounts of flux, for example, NH4Cl. The mixture may be fired in an alumina crucible in a first step at about 1,100° C. for about 2 hours in the air. After milling the pre-fired materials a second firing step at about 1,220° C. in the air for about 4 hours and in a reduced atmosphere for about 1 hour may be followed. After that the material may be milled, washed, dried and sieved. The resulting luminescent material may have an emission maximum at about 492 nm.
Results obtained with respect to copper and/or lead doped silicates are shown in table 12.
With lead and/or copper doped antimonates having formula (14)
a(M′O).b(M″2O).c(M″X).d(Sb2O5).e(M′″O).f(M″″xOy) (14)
Examples of Preparation:
Preparation of the Luminescent Material Having Formula (15)
Cu0.2Mg1.7Li0.2Sb2O7:Mn (15)
Starting materials: CuO, MgO, Li2O, Sb2O5, MnCO3, and/or any combination thereof.
The starting materials in the form of oxides may be mixed in stoichiometric proportion together with small amounts of flux. In a first step the mixture may be fired in an alumina crucible at about 985° C. in the air for about 2 hours. After pre-firing the material may be milled again. In a second step the mixture may be fired in an alumina crucible at about 1,200° C. in an atmosphere containing oxygen for about 8 hours. After that the material may be milled, washed, dried and sieved. The resulting luminescent material may have an emission maximum at about 626 nm.
Preparation of the Luminescent Material Having Formula (16)
Pb0.006Ca0.6Sr0.394Sb2O6 (16)
Starting materials: PbO, CaCO3, SrCO3, Sb2O5, and/or any combination thereof.
The starting materials in the form of oxides and/or carbonates may be mixed in stoichiometric proportions together with small amounts of flux. In a first step the mixture may be fired in an alumina crucible at about 975° C. in the air for about 2 hours. After pre-firing the material may be milled again. In a second step the mixture may be fired in an alumina crucible at about 1,175° C. in the air for about 4 hours and then in an oxygen-containing atmosphere for about 4 hours. After that the material may be milled, washed, dried and sieved. The resulting luminescent material may have an emission maximum at about 637 nm.
Results obtained in respect to copper and/or lead doped antimonates are shown in table 15.
Lead and/or copper doped germanates and/or a germanate-silicates having formula (17)
a(M′O).b(M″2O).c(M″X)·dGeO2.e(M′″O).f(M″″2O3).g(M′″″oOp).h(M″″″xOy) (17)
Example of Preparation:
Preparation of the Luminescent Material Having Formula (18)
Pb0.004Ca1.99Zn0.006Ge0.8Si0.2O4:Mn (18)
Starting materials: PbO, CaCO3, ZnO, GeO2, SiO2, MnCO3, and/or any combination thereof.
The starting materials in the form of oxides and/or carbonates may be mixed in stoichiometric proportions together with small amounts of flux, for example, NH4Cl. In a first step the mixture may be fired in an alumina crucible at about 1,200° C. in an oxygen-containing atmosphere for about 2 hours. Then, the material may be milled again. In a second step the mixture may be fired in an alumina crucible at about 1,200° C. in oxygen containing atmosphere for about 2 hours. After that the material may be milled, washed, dried and sieved. The resulting luminescent material may have an emission maximum at about 655 nm.
Preparation of the Luminescent Material Having Formula (19)
Cu0.46Sr0.54Ge0.6Si0.4O3:Mn (19)
Starting materials: CuO, SrCO3, GeO2, SiO2, MnCO3, and/or any combination thereof.
The starting materials in the form of oxides and/or carbonates may be mixed in stoichiometric proportions together with small amounts of flux, for example, NH4Cl. In a first step the mixture may be fired in an alumina crucible at about 1,100° C. in an oxygen-containing atmosphere for about 2 hours. Then, the material may be milled again. In a second step the mixture may be fired in an alumina crucible at about 1,180° C. in an oxygen-containing atmosphere for about 4 hours. After that the material may be milled, washed, dried and sieved. The resulting luminescent material may have an emission maximum at about 658 mm.
Lead and/or copper doped phosphates having formula (20)
a(M′O).b(M″2O).c(M″X).dP2O5.e(M′″O).f(M″″2O3).g(M′″″O2).h(M″″″xOy) (20)
Examples of Preparation:
Preparation of the Luminescent Material Having Formula (21)
Cu0.2Ca4.98(PO4)3Cl:Eu (21)
Starting materials: CuO, CaCO3, Ca3(PO4)2, CaCl2, Eu2O3, and/or any combination thereof.
The starting materials in the form of oxides, phosphates, and/or carbonates and chlorides may be mixed in stoichiometric proportions together with small amounts of flux. The mixture may be fired in an alumina crucible at about 1,240° C. in reducing atmosphere for about 2 hours. After that the material may be milled, washed, dried and sieved. The luminescent material may have an emission maximum at about 450 nm.
Meanwhile, the phosphor of the light emitting device consistent with this invention can comprise aluminate, silicate, antimonate, germanate, phosphate type chemical compound, and any combination thereof.
In such an embodiment, part of the initial about 405 nm wavelength emission light from the light emitting diode is absorbed by the phosphor, and it is converted to longer 2nd wavelength. The 1st and 2nd light is mixed together and the desire emission is produced. As the shown
The phosphor is composed of Cu0.05Sr1.7Ca0.25SiO4:Eu which may have peak wavelength at about 592 nm, Pb0.1Ba0.95Sr0.95Si0.998Ge0.002O4:Eu which may have peak wavelength at about 527 nm, and Cu0.05Li0.002Sr1.5Ba0.448SiO4:Gd, Eu which may have peak wavelength at about 557 nm.
In such an embodiment, part of the initial about 455 nm wavelength emission light from the light emitting diode is absorbed by the phosphor, and it is converted to longer 2nd wavelength. The 1st and 2nd light is mixed together and the desire emission is produced. As the shown
The phosphor of the light emitting device according to the invention can be applied by single chemical compound or mixture of plurality of single chemical compound besides the embodiments in relation to
According to the description above, light emitting device with wide range of color temperature about 2,000K or about 8,000K or about 10,000K and superior color rendering index more than about 90 can be realized by using the lead and/or copper doped chemical compounds containing rare earth elements.
In such a wavelength conversion light emitting device is capable of applying on mobile phone, note book and electronic devices such as home appliance, stereo, telecommunication products, but also for custom display's key pad and back light application. Moreover, it can be applied for automobile, medical instrument and illumination products.
According to the invention, it is also able to provide a wavelength conversion light emitting device with stability against water, humidity, vapor as well as other polar solvents.
In the foregoing described embodiments, various features are grouped together in a single embodiment for purposes of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the following claims are hereby incorporated into this Detailed Description of Embodiments, with each claim standing on its own as a separate preferred embodiment of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2004-0042396 | Jun 2004 | KR | national |
