CN1677695A - white light emitting diode unit - Google Patents

Abstract

The invention relates to a white light LED unit, which comprises a substrate; at least one blue light emitting diode on the substrate; a mixed phosphor comprising a red phosphor, a green phosphor and a yellow phosphor; and is coated outside the blue light emitting diode. The red phosphor can adopt CaS: Eu or SrS: Eu; the yellow silvery substance can be YAG Ce or TbAG Ce; as the green phosphor, SrGa is used₂S₄Eu or Ca₈EuMnMg(SiO₄) ₄C₁₂So as to mix the blue light of the blue light emitting diode to obtain the white light with high color rendering.

Description

white light emitting diode unit

technical field

The invention relates to a white light emitting diode unit, in particular to a white light emitting diode unit having both luminous efficiency and color rendering.

Background technique

White light is multi-color mixed light, which can be perceived as white light by human eyes, and includes at least two or more wavelengths of mixed light. For example, when the human eye is stimulated by red, blue, and green light at the same time, or when it is stimulated by blue light and yellow light at the same time, it can be perceived as white light. Therefore, a semiconductor light emitting device capable of emitting white light can be manufactured according to this principle. The manufacturing methods of the existing white light semiconductor light emitting devices are described as follows.

The first way is to use three red, blue and green light-emitting diodes made of aluminum gallium indium phosphide (AlInGaP), indium gallium nitride (InGaN) and gallium phosphide (GaP) to control the current passing through each light-emitting diode, while Make it emit red, green and blue light respectively. The three LED chips are arranged in the same lamp, and the three colors of light are mixed by a lens to generate white light. As shown in FIG. 1A , a red light emitting diode LR, a green light emitting diode LG and a blue light emitting diode LB can be arranged on a substrate 10 and covered with an encapsulant 11 for protection. FIG. 1B shows the emission spectrum of this existing white light unit. It can be seen that the emission spectra of the red LED LR, the green LED LG and the blue LED LB are separated in the center and not widely distributed. Since the white light is formed by the spectrum continuously distributed between 400-720nm, the color saturation of the existing white light emitting diode is low. Although human eyes can ignore this phenomenon and only see white light, under the sensing of some high-precision optical detectors, such as video cameras or cameras, the color rendering property (color rendering property) is still essentially the same. On the low side. Furthermore, when one of the LEDs with different light colors breaks down, normal white light cannot be obtained, and overall, the luminous efficiency is poor.

The second method is the technology developed by Nichia Chemical Company in Japan in 1996. It uses indium gallium nitride blue light-emitting diodes combined with yttrium-aluminum-garnet-type phosphors that can emit yellow light when excited. Make a white light source. Since this method only needs to use a set of light-emitting diode chips, the manufacturing cost can be greatly reduced. Referring to Fig. 2, for the schematic diagram of the prior art, a blue light-emitting diode LB can be placed on the substrate 10, and a yellow phosphor PY is covered on it, so as to absorb the blue light-emitting diode LB and emit yellow light, which is mixed with the blue light become white light. Now, the phosphor modulation technology that it is matched with has reached maturity, so there are already commercial products. However, the color rendering of this white light emitting diode is even worse.

Contents of the invention

The main purpose of the present invention is to provide a white light emitting diode unit capable of both luminous efficiency and color rendering, so as to solve the above-mentioned shortcomings of the existing white light emitting diodes.

In order to achieve the above object, the present invention provides a white light emitting diode unit, which includes a base material, such as an insulating base material; at least one blue light emitting diode, located on the base material, and can be made of a nitride compound semiconductor It is made; a mixed fluorescent body, including red fluorescent body, green fluorescent body and yellow fluorescent body; and coated on the outside of the blue light-emitting diode. The red phosphor can be Cas:Eu or SrS:Eu; the yellow silver phosphor can be YAG:Ce or TbAG:Ce; the green phosphor can be SrGa ₂ S ₄ :Eu or Ca ₈ EuMnMg(SiO ₄ ) ₄ C ₁₂ , in order to match the blue light of the blue light-emitting diode to mix high color rendering white light. In addition, the white light emitting diode unit may be a surface mount type light emitting diode unit or a light bulb type light emitting diode unit. The light emitting wavelength of the blue light emitting diode is 400-490nm. Moreover, the red phosphor, the green phosphor and the yellow phosphor can be prepared in a certain proportion to change the light emitting color temperature of the white light emitting diode unit.

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments, but not as a limitation of the present invention.

Description of drawings

FIG. 1A is a schematic diagram of an existing white light unit;

Fig. 1B is a spectrum diagram of an existing white light unit;

2 is a schematic diagram of another conventional white light unit;

Fig. 3 is a schematic diagram according to a preferred embodiment of the present invention;

Fig. 4A is a schematic diagram according to another preferred embodiment of the present invention;

Fig. 4B is a spectral diagram of the assembly of Fig. 4A.

Detailed ways

As shown in FIG. 3 , it is a schematic diagram of a white light emitting diode unit 2 according to a preferred embodiment of the present invention. The white light emitting diode comprises a substrate 20, a blue light emitting diode LB positioned on the substrate 20, and a red phosphor PR and a green phosphor PG positioned on the blue light emitting diode LB, the red phosphor PR and the green phosphor The phosphor PG can absorb the blue light of the blue light-emitting diode LB to emit red light and green light respectively, and mix with the blue light of the blue light-emitting diode LB to form white light.

Among the red and green phosphors described above, Cas:Eu or SrS:Eu can be used for the red phosphor; YAG:Ce or TbAG:Ce can be used for the yellow silver phosphor; SrGa ₂ S ₄ :Eu can be used for the green phosphor or Ca ₈ EuMnMg(SiO ₄ ) ₄ C ₁₂ . However, it should be noted that there are other phosphors that can be used besides the above-mentioned phosphors, but it does not mean that the invention of this case is limited to the above-mentioned phosphors, and also includes other phosphor materials that can be excited by blue light wavelength (400-490nm).

Please refer to FIG. 4A , which is a schematic diagram of a white light emitting diode unit 2 according to another preferred embodiment of the present invention. The white light emitting diode unit 2 includes a base material 20 (such as an insulating base material), a blue light emitting diode LB (which can be made of a nitride compound semiconductor) on the base material 20, and a blue light emitting diode LB on the base material 20. The red, green and yellow mixed phosphor PRG on the color light-emitting diode LB, wherein the mixed phosphor RGY includes the mixed result of the red phosphor PR, the green phosphor PG and the yellow phosphor PY.

The above-mentioned white light emitting diode unit 2 is provided with a wire part (not shown), and the cathode and anode of the blue light emitting diode LB can be connected to the electrical connection part (not shown) of the base material 20 to supply power to the blue light emitting diode unit 2. LED on LB. However, the electrode connection technology of the blue light-emitting diode LB is a prior art, which is not the focus of the present invention, so it will not be repeated here. Furthermore, the above-mentioned white light emitting diode unit is a surface mount package, but it should be noted that the white light emitting diode unit may also be packaged in other forms, such as a light bulb package.

When the above-mentioned blue LED chip LB is proficient in current and emits blue light, it can excite the red phosphor PR, green phosphor PG and yellow phosphor PY in the mixed phosphor RGY, and generate red light and green light. and yellow light emission.

Please refer to FIG. 4B, which is the emission spectrum of the white light emitting diode unit 2 of a preferred embodiment of the present invention, from left to right are the spectrum of the blue light emitting LB, the emission spectrum of the green phosphor PG, and the emission of the yellow phosphor PY The spectrum is the same as the emission spectrum of the red phosphor PR and the spectrum of the prior art (see FIG. 1B ). The emission spectrum of the white light emitting diode unit 2 of the present invention covers a broader visible light band, so it has better color rendering. Furthermore, generally speaking, the emission spectrum of the phosphor is wider than that of the light-emitting diode, because better color rendering can be achieved.

Because the color rendering of white light is not good when only yellow light phosphor is used, red and green light phosphors are added to the fluorescent glue to increase its color rendering. The red, yellow, and green phosphors can be mixed in an appropriate proportion to obtain white light or to adjust various color temperatures and shades.

In the red, green and yellow mixed phosphor PGY of the present invention, the red phosphor can be Cas:Eu or SrS:Eu; the yellow silver phosphor can be YAG:Ce or TbAG:Ce; and the green phosphor can be SrGa ₂ S ₄ : Eu or Ca ₈ EuMnMg(SiO ₄ ) ₄ C ₁₂ . However, it should be noted that there are other available phosphors in addition to the above-mentioned phosphors, but it does not mean that the present invention is limited to the above-mentioned phosphors, and also includes other phosphor materials that can be excited by blue light wavelengths (400-490nm).

In summary, the white light emitting diode unit of the present invention can have both luminous efficiency and color rendering.

Of course, the present invention can also have other various embodiments, and those skilled in the art can make various corresponding changes and deformations according to the present invention without departing from the spirit and essence of the present invention, but these corresponding Changes and deformations should belong to the scope of protection of the appended claims of the present invention.

Claims (10)

1. A white light emitting diode unit, characterized in that it comprises: a substrate; at least one blue light emitting diode located on the substrate; A mixed phosphor includes red phosphor, green phosphor and yellow phosphor; and is coated on the outside of the blue light-emitting diode. 2. The white light emitting diode unit according to claim 1, wherein the red phosphor can be Cas:Eu or SrS:Eu. 3. The white light emitting diode unit according to claim 1, wherein the green phosphor can be SrGa ₂ S ₄ :Eu or Ca ₈ EuMnMg(SiO ₄ ) ₄ C ₁₂ . 4. The white light emitting diode unit according to claim 1, wherein the yellow phosphor can be YAG:Ce or TbAG:Ce. 5. The white light emitting diode unit according to claim 1, wherein the white light emitting diode unit is a surface mount type light emitting diode unit. 6. The white light emitting diode unit according to claim 1, wherein the white light emitting diode unit is a light bulb type light emitting diode unit. 7. The white light emitting diode unit according to claim 1, wherein the base material is an insulating material. 8. The white light emitting diode unit according to claim 1, wherein the blue light emitting diode is made of a nitride compound semiconductor. 9. The white light emitting diode unit according to claim 1, characterized in that, the light emitting wavelength of the blue light emitting diode is 400-490nm. 10. The white light emitting diode unit according to claim 1, wherein the red phosphor, the green phosphor and the yellow phosphor can be mixed in a certain ratio to change the color temperature of the white light emitting diode unit.

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