Light-emitting diode unit

FIELD: physics, optics.

SUBSTANCE: LED unit, having a LED chip (10), a phosphor layer (12) and a filter layer (14), which is arranged such that light rays emitted from the LED chip (10), with a radiation angle less than a predetermined angle to the normal of the filter, are at least partially reflected, and light rays emitted from the LED chip higher than said predetermined angle to the normal of the filter layer (14) are transmitted.

EFFECT: invention enables to make a LED unit which solves the problem of yellow ring without reducing the efficiency of the LED unit.

14 cl, 2 tbl, 5 dwg

The technical FIELD TO WHICH the INVENTION RELATES

The present invention relates to the field blocks light emitting diodes (LED). In particular, the invention relates to blocks light LED devices with improved phosphors radiation (pcLED). Such assemblies are often used to provide white light.

PRIOR art

LED emitting white light, as a rule, contain LED blue light, combined with a layer of phosphor which is stimulated by blue light LED in the emitted yellow light, the combination of yellow and blue radiation, provides white light. For the direction of the normal perpendicular to the surface of the LED crystal or vertically to the surface of the phosphor layer with a radiation angle of 0°, the path length of light rays in the phosphor layer emitted by the LED blue light, equal to the thickness of the layer of phosphor. To increase the angles of the radiation path length of the blue light rays increases. Thus, the proportion of blue light rays being absorbed by the phosphor layer below the light with the emission angle of 0°than for light rays with increasing angle of radiation. Because the converted light emitted by the phosphor layer always has an angular distribution according to the law of Lambert, white light emitted by the LED has a higher correlated color temperature is the tour for normal radiation with a radiation angle of approximately 0°. Typically, the phosphor layer is a Y₃Al₅O₁₂:Ce³⁺(YAG:Ce). In the case of a YAG:Ce phosphor layer emitted light becomes yellowish with increasing angle of radiation, and is perceived as yellow ring. To solve the yellow ring is known to increase the scattering capability of the layer of phosphor and/or adding a scattering layer over a layer of phosphor. For both solutions reduce the problem of the yellow ring reduces the efficiency of the LED, because the scattering is accompanied by a reflection of light, leading to the loss of light. In particular, the dispersion of the phosphor with the low frequency of the radiated light leads to reflection with accompanying losses in the reflection.

The INVENTION

The objective of the invention is the provision of a unit light-emitting diode (LED), which solves the above problem of the yellow ring without reducing the efficiency of the LED unit.

The unit light-emitting diode (LED) according to the invention contains the LED chip, the phosphor layer and the filter layer, the filter layer is designed so that light rays with a wavelength of approximately 400 nm to 500 nm, preferably from about 420 nm to 490 nm, emitted by the LED crystal at least partially reflected depending on the angle of radiation relative to the normal to Phil who traymenu layer.

LED crystal preferably is a blue LED radiation. The phosphor layer preferably is a Y₃Al₅O₁₂:Ce³⁺(YAG:Ce). The filter layer preferably is a dielectric filter layer. This filtering layer allows full transmission of light rays emitted by the LED crystal, regardless of their wavelength within the range of visibility for large angles of radiation, preferably radiation angle between 30° and 90° to the normal of the filter. For smaller angles of radiation preferred angles of radiation between 0° and 30° relative to the normal to the filter layer, provided partial reflection of light rays with a wavelength of approximately 400 nm to 500 nm. Light rays with a wavelength of approximately 400 nm to 500 nm are blue light rays emitted by the LED chip. Partial reflection of the blue light rays emitted by the LED chip, depending on their angle of radiation relative to the normal to the filter layer, provide uniformity in the corners of radiation without loss of efficiency of the light emitted by the LED. The normal to the filter layer is a vertical axis to a flat surface of the filter layer.

For homogeneous white light emitted by the LED chip, the ratio of the intensity of halogen with exceptiona is directly emitted light from the LED chip, and is converted by the phosphor layer of the light is constant for all angles. Normally, the light emitted by the LED, provides a conical shape in the region of small angle of radiation, preferably radiation angle of approximately 0° to 30° relative to the normal to the filter layer. However, the yellow light emitted by the LED chip, usually provides a spherical shape at all angle of radiation of from about 0° to 90°. Thus, there are areas, especially at high angles of radiation, preferably between 30° and 90°, where the ratio of blue light to yellow decreases. Radiation under these angles are caused by the problem of the yellow ring. Through reflection, a certain amount of blue light at low angles of radiation of from about 0° to 30° is possible transformation of cone-shaped blue light in a spherical shape so that the blue and yellow light had the same attitude at all angle of radiation from 0° to 90°. Thus, the superposition of yellow and blue light in the entire angle of radiation received so that a homogeneous white light was radiated by the LED unit on the entire angle of radiation without problems yellow rings.

Preferably, the filter layer reflects light rays from a radiation angle of approximately 0° to 30°, preferably from 0° to 20°relative to the normal to the filter layer. The reflected light rays are blue light rays emitted from the ETA LED crystal with a wavelength of approximately 400 nm to 500 nm, preferably from about 420 nm to 490 nm.

In a preferred embodiment of the invention from about 10% to 50%, preferably from about 15% to 30% of the light rays emitted by the LED chip, reflected by the filter layer depending on their angle of radiation. The reflected light rays are blue light rays emitted light LED crystal with a wavelength of approximately 400 nm to 500 nm, preferably from about 420 nm to 490 nm. Thus, approximately 10% to 50%, preferably from 15% to 40% of blue light rays emitted by the LED to radiation angle of approximately 0° to 40°, preferably from approximately 0° to 30° relative to the normal to the filter layer, are shown. The remaining blue light rays emitted by the LED to radiation angle of approximately 0° to 40°, preferably from approximately 0° to 30°, pass through the filter layer without reflection.

The filter layer preferably contains a layer of dielectric coatings consisting of alternating materials of high and low refractive index. Alternating materials of high and low refractive index can be selected in such a way that can be achieved accurately directed to the reflection of the blue light emitted by LED Krista is La.

The material layer dielectric coatings are preferably permeable to the wavelength between 400 nm and 800 nm with a refractive index of materials of high refractive index in the range from 1.6 to 3 and with a refractive index of a material of low refractive index in the range from 1.2 to 1.8. The absorption coefficient of the designated materials is <0,00001 for wavelength >480 nm and <0,003 for wavelength >400 nm. Nb₂O₅(niobium oxide) is preferably used as a material with a high refractive index, and SiO₂(silicon oxide) is preferably used as a material with low refractive index.

Preferably, the filter layer contains nine layers of materials with high refractive index and nine layers of materials with low refractive index. Layers can be deposited by techniques of deposition of thin film coatings, such as chemical vapor deposition or sputtering.

According to a preferred variant of the invention, the filter layer is located between the LED chip and the phosphor layer. Thus, the filter layer is located above the LED chip, and the phosphor layer is located on top of the filter layer.

According to another variant of the invention, the phosphor layer offers the wives top LED crystal and the filter layer is the top layer of phosphor.

Additionally, according to an additional variant of the invention, it is possible to provide the LED unit is the first layer of phosphor and the second phosphor layer, where the filter layer is located between the first layer of phosphor and the second phosphor layer. Preferably, the first phosphor layer is located above the LED chip.

The phosphor layer may contain a plate Lumiramic and/or the phosphor is placed in a transparent matrix material. Plate Lumiramic is a polycrystalline ceramic plate Ce (III), alloy yttrium-gadolinium garnet (Y, GdAG:Ce). A significant advantage is the combination of such plates Lumiramic LED crystal blue light to produce white light in the range of 5000 K correlated color temperature. The dispersion and isolation of light through the ceramic svetoprozrachnymi plates Lumiramic makes it possible to manufacture a reliable and efficient white pcLED. Measurement of the optical properties of the plates Lumiramic to the final Assembly LED allows you to choose and place a layout with exact positioning of the desired white point color LED.

Preferably, the LED array can provide a transparent glass plate, which functions as a substrate for the filter layer. Thus, the filter layer is e must be applied directly on the LED chip, the phosphor layer. The filter layer can be easily deposited on a transparent glass plate and after application of the filtering layer on the glass plate it is made with the possibility of applying to the LED unit.

According to a preferred variant of the invention, the filter layer has a final thickness of from 750 nm to 950 nm, preferably from about 800 nm to 900 nm.

Additionally, according to a variant embodiment of the invention, the phosphor layer has a thickness of approximately 80 μm to 150 μm, preferably from about 100 μm to 130 μm.

In addition, the thickness of the layers of materials of high refractive index preferably ranges from 5 μm to approximately 70 μm and the thickness of the layers of materials of low refractive index preferably ranges from approximately 20 nm to 300 nm.

BRIEF DESCRIPTION of DRAWINGS

These and other aspects of the invention will become apparent and described with reference to options for implementation and accompanying drawings, in which:

Figure 1 depicts a schematic view of the first variant implementation unit of the led according to the invention;

Figure 2 depicts a graph showing the transmittance of the filter layer of the invention, depending on the angle of radiation and the wavelength of the light emitted by LED crystal;

Figure 3 depicts a chart on asiausa geometric distance of the color coordinates to the coordinates of the color in the normal radiation in a Uniform Color Space (CIE 1976) block white LED;

Figure 4 depicts a schematic view of the second variant implementation unit of the led according to the invention; and

Figure 5 depicts a schematic view of the third variant of the implementation unit of the led according to the invention.

DETAILED DESCRIPTION of embodiments of the INVENTION

Figure 1 shows a first variant implementation of the unit light emitting diode (LED) according to the invention with LED crystal 10, the phosphor layer 12 and the filter layer 14. LED crystal 10, the phosphor layer 12 and the filter 14 is preferably closed by a housing 16 semicircular shape, which may have a reflective coating on its inner wall. LED crystal 10, which emits blue light with a wavelength of approximately 400 nm to 500 nm is located on the substrate unit 18 LED. Top LED crystal 10 is a layer 12 of the phosphor. The layer 12 of the phosphor emits yellow light with a wavelength of from about 570 nm to 590 nm. The phosphor layer 12 may contain a plate Lumiramic and/or the phosphor is placed in a transparent binder material. The thickness of the layer 12 of the phosphor is from about 100 μm to 120 μm. The top layer 12 of the phosphor is filter layer 14. The filter layer 12 includes a layer of dielectric coating consisting of alternating materials of high and low refractive index, such as Nb₂O₅and SiO₂.

Figure 2 shows on agrama, showing the transmittance of the filter layer 14 according to the invention depending on the angle of radiation and the wavelength of the light emitted by the LED chip. The filter layer 14, shown in the diagram has the layer structure shown in the following table 1:

The various lines shown on the diagram represent different angles of radiation 0°, 26°, 40° and 77°. As you can see, for large angles of radiation, such as 40° and 77°, the light rays regardless of their wavelength is able to pass through the filter layer 14 without any reflection or absorption. When this angle radiation transmittance of the emitted light rays, especially the blue emitted light rays is approximately 100%. For small angles of radiation, such as 0° and 26°, blue light rays with a wavelength of from 400 nm to 500 nm is not able to fully pass through the filter layer. When this angle radiation transmittance of the emitted light rays is approximately 80%. Approximately 20% of the blue light rays reflected by the filter layer 14. Yellow light rays layer 12 phosphor with a wavelength of approximately 520 nm to 650 nm is able to pass through the filter layer regardless of the angle of radiation. Thus, the filter layer 14 only reflects a certain amount of blue emitted light rays. Partial reflection of the blue light rays emitted by LED crystal 10 depending on their angle of radiation relative to the normal to the filter layer 14 provide uniformity in the corners of radiation without loss of efficiency of the light emitted by the LED to what estalla 10, because the blue light is reflected from the filter layer, is absorbed by the phosphor layer and converted into radiation of the phosphor.

The filter layer 14 may also have a layer structure, shown in the following table 2:

Figure 3 shows the geometric distance of the color coordinates to the coordinates of the color in the normal radiation in a Uniform Color Space (CIE 1976) block white LED without (solid line) and with (dashed line) filter layer according to the invention, depending on the radiation angle of the emitted light rays. How can what to put on the chart, using the filter layer 14 according to the invention may receive almost constant color light rays emitted by LED blocks regardless of the angle of radiation of light rays.

Figure 4 shows a schematic view of the second variant implementation unit of the led according to the invention. In this embodiment, the filter layer 14 is located between the LED crystal 10 and the phosphor layer 12.

Figure 5 shows a schematic view of the third variant of the implementation unit of the led according to the invention, the LED array includes a first layer 12 of the phosphor and the second phosphor layer 20. The filter layer 14 is located between the first phosphor layer 12 and second layer 20 of the phosphor, the first phosphor layer 12 is located on the top LED crystal 10.

Although the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description should be considered illustrative or exemplary and not restrictive, the invention is not limited to the variants described here implement.

Other variations of the described embodiments can be understood and implemented in practice by experts in the area described in the application of the invention, by studying the drawings, the disclosure and the accompanying formula is subramania. In the claims, the word "comprising" does not exclude other elements or steps, and the reference objects of the invention in the singular not plural. The fact that certain measurements stated in mutually different dependent clauses, does not mean that the combination of these measures cannot be used as an advantage. Any instructions on the reference materials in the claims should not be construed as limiting the scope.

1. LED unit containing
LED crystal (10),
layer (12) of the phosphor and
the filter layer (14), which is located so that light rays emitted from the LED chip (10), with the angle of radiation below a predefined angle relative to the normal of the filter is at least partially reflected, and the light rays emitted from the LED crystal above this predetermined angle relative to the normal to the filter layer (14) are ignored.

2. The LED unit of claim 1, wherein the filter layer (14) partially completed with the possibility of reflection of light rays with an angle of radiation of from about 0° to 30°, preferably from about 0° to 20°relative to the normal to the filter layer (14).

3. The LED unit according to claim 1 in which from about 10% to 50%, preferably from 15% to 30%, of the light rays emitted by the LED chip (10) is reflected in the dependence the value of their radiation angle to the normal of the filter (14).

4. The LED unit of claim 1, wherein the filter layer (14) contains a layer of dielectric coating consisting of alternating materials of high and low refractive index.

5. The LED unit according to claim 4, in which the material layer dielectric coating permeable to the wavelength between 400 nm and 800 nm with a refractive index materials with high refractive index in the range from 1.6 to 3 and with a refractive index materials with a low refractive index in the range from 1.2 to 1.8.

6. The LED unit according to claim 4, which is provided with nine layers of materials with high refractive index and nine layers of materials with low refractive index.

7. The LED unit of claim 1, wherein the filter layer (14) is located between the LED chip (10) and the layer (12) of the phosphor.

8. The LED unit according to claim 1, in which the layer (12) of the phosphor is located on top of the LED chip (10) and the filter layer (14) is located on the top layer (12) of the phosphor.

9. The LED unit of claim 1, wherein the LED array includes a first layer (12) of the phosphor and the second layer (20) of the phosphor, while the filter layer (14) is located between the first layer (12) of the phosphor and the second layer (18) of the phosphor.

10. The LED unit according to claim 1, in which the layer (12) of the phosphor plate contains Lumiramic and/or the phosphor is placed in a transparent matrix material.

11. The LED unit according to claim 1, in which a transparent glass plate is provided as the mean is the LCD for the filter layer (14).

12. The LED unit of claim 1, wherein the filter layer (14) has a total thickness of from 750 nm to 950 nm, preferably from 800 nm to 900 nm.

13. The LED unit according to claim 1, in which the layer (12) of the phosphor has a thickness of approximately 80 μm to 150 μm, preferably from about 100 μm to 130 μm.

14. The LED unit according to claim 4, in which the thickness of the layers of materials with high refractive index varies from 5 nm to approximately 70 nm and the thickness of the layers of materials with low refractive index ranging from approximately 20 nm to 300 nm.