TW201324875A - Method of enhancing color rendering index of a white LED - Google Patents

Abstract

The present invention discloses a method of enhancing color rendering index of a white light emitting diode (white LED), and particularly discloses a method of enhancing color rendering index of a white LED by adding a blue-green (or aquamarine) phosphor which can emit a light having wavelength of 485 nm to 519 nm.

Description

Method for enhancing color rendering of white light emitting diode

The invention provides a method for enhancing the color rendering of a white light emitting diode, in particular to a method for enhancing the color rendering of a white light emitting diode by using blue-green fluorescent powder.

Recently, Light Emitting Diode (LED) has the advantages of power saving, environmental protection, long service life and fast response speed, and gradually replaces traditional U-shaped bulbs or fluorescent lamps as emerging lighting tools, and is applied to Various fields, such as liquid crystal displays, road lighting, road signs and other fields. In general, the most widely used LEDs are white LEDs that mimic sunlight.

Most of today's white LEDs are packaged in a blue light-emitting diode with different phosphors to form a white LED that produces white light. The main technology of white LED manufacturing is to apply a layer of yellow phosphor powder, such as YAG yellow phosphor powder, TAG yellow phosphor powder, etc., to a blue light-emitting diode (wavelength 430nm-480nm), and emit light by blue light. The blue light emitted by the diode grains excites the yellow phosphor to emit yellow light, and the yellow light emitted by the yellow phosphor is mixed with the blue light emitted by the blue light emitting diode crystals, and the blue light and the yellow light The complementary effect produces white light.

Referring to the first figure and Table 1, the first picture shows the spectrum of the white light LED made of blue light emitting diode crystal and yellow fluorescent powder (YAG), and the first one shows the brightness and color rendering of the white light LED (Color Rendering) Index; CRI) test results.

Table I

It can be seen from the first figure and Table 1 that the average brightness of white LEDs made of blue light-emitting diode grains and yellow phosphor powder (YAG) is about 6.1505 lm, and the average color rendering is about 75.3582. Most of its color rendering is between 70-75.

Therefore, the color rendering of the white LED produced by this technology obviously does not meet the requirements of the current requirement that the color rendering of the white LED needs to reach 80 or more. In view of this, a white LED incorporating a red phosphor and a yellow phosphor is further developed to achieve high color rendering (CRI > 80). However, since the addition of red phosphor powder can increase the color rendering of white LEDs, the increase is not large, so a large amount of red phosphor needs to be added to achieve high color rendering requirements, and this approach has two disadvantages: (1) Adding a large amount of red fluorescent powder will cause the light emitted by the white LED to change color and not emit white light. Therefore, it is necessary to add green fluorescent powder for correction so that the white LED can emit white light; (2) due to the addition of a large amount of The red fluorescent powder and the green fluorescent powder have a certain improvement in the color rendering of the white LED, and the color rendering property can be increased to more than 80, and the color rendering property is increased, but the brightness thereof is greatly reduced.

In addition, another technology has been developed to make white LEDs, which add red and green phosphors to the blue light-emitting diode, red and green phosphors to blue by the blue light-emitting diode. The excitation of the chromatic light emits red light and green light, respectively, and white light is produced by mixing blue light, red light, and green light. Referring to the second and second tables, the second figure shows the spectrum of the white LEDs made of blue light-emitting diode crystals, red phosphor powder and green phosphor powder, and the second table shows the brightness and color rendering of the white LEDs. Sexual test results.

Table II

It can be seen from the second figure and the second table that the average brightness of the white LEDs prepared by adding the red phosphor powder and the green phosphor powder to the blue light emitting diode crystal grains is about 4.847952 lm, and the average color rendering property is about 78.181. Left and right, its color rendering is mostly between 75-79. Therefore, the color rendering (CRI) of the white LED produced by this technology cannot meet the requirement of producing high color rendering (CRI>80), and conversely, the brightness of the white LED is greatly reduced.

Therefore, there is an urgent need for a method for enhancing the color rendering of a white LED, which can greatly increase the color rendering of a white LED without changing the color of the light emitted by the white LED, nor greatly Reduce the brightness of white LEDs.

An object of the present invention is to provide a method for enhancing the color rendering of a white LED, which can greatly increase the color rendering of a white LED without changing the color of the light emitted by the white LED, nor will it Greatly reduce the brightness of white LEDs.

It is an object of the present invention to provide a method for enhancing the color rendering of a white LED, which can be applied to any conventional LED package process in a simple and without significantly changing the original process steps. Effectively enhances the color rendering of white LEDs while maintaining sufficient brightness.

According to one aspect of the present invention, a method for enhancing the color rendering of a white LED (white LED) includes: providing a light emitting diode die for white LED packaging, and emitting LED crystals a package of particles to form a white light emitting diode; and a blue-green phosphor added to the packaged light-emitting diode process to absorb a portion of the light emitted by the light-emitting diode die to excite The light of the blue-green wavelength is mixed with the light emitted by the light-emitting diode to enhance the color rendering of the white light-emitting diode. The blue-green phosphor is a phosphor that emits light having a wavelength of 485 nanometers (nm) to 519 nanometers (nm).

Accordingly, the present invention provides a method of not significantly changing the color of light emitted by a white LED and greatly reducing the brightness of the white LED, but greatly enhancing the color rendering of the white LED.

Some embodiments of the invention are described in detail below. However, the present invention may be widely practiced in other embodiments in addition to the detailed description. That is, the scope of the present invention is not limited by the embodiments of the present invention, and the scope of the patent application proposed by the present invention shall prevail. In the following, when the elements or steps in the embodiments of the present invention are described in a single element or step description, the present invention should not be construed as limiting, that is, the following description does not particularly emphasize the numerical limitation. The spirit and scope of application can be derived from the structure and method in which many components or structures coexist. In addition, in the present specification, the various parts of the elements are not drawn in full accordance with the dimensions, and some dimensions may be exaggerated or simplified compared to other related dimensions to provide a clearer description to enhance the understanding of the present invention. The prior art of the present invention, which is used in the prior art, is only referred to herein by reference.

Referring to the third figure, it is a flowchart of a method for enhancing the color rendering of a white light emitting diode according to an embodiment of the present invention. First, a light emitting diode die is provided, and a white light emitting diode is packaged by the light emitting diode die (white LED) to form a white light emitting diode (step 100). Wherein, the light-emitting diode crystal grains are blue light-emitting diode crystal grains, but not limited thereto, but may adopt other light-emitting according to the design, planning, demand or white LED structure of the white LED packaging process. The diode is packaged, such as a violet light emitting diode. Secondly, the encapsulation process of the light-emitting diode die comprises a solid crystal, and the light-emitting diode is fixed on a substrate by a solid crystal glue; baking is used to solidify the solid crystal glue to fix the light-emitting diode die On the substrate; a bonding wire for wire bonding the LED electrode to the substrate guide pin; dispensing for adding a phosphor glue to form a white LED capable of exciting white light; baking for curing the package Colloid; and testing, for functional testing and judging good and other steps. However, the packaging process of the light-emitting diode die adopted by the present invention is not limited to the above steps, but may be increased, decreased, or according to the design, planning, requirements, or white LED structure of the white LED packaging process. It is to change the process steps.

Then, a blue-green phosphor is added to the packaged LED process (step 102), and the blue-green phosphor can absorb a part of the light emitted by the LED chip to excite the wavelength. The blue-green light in the range of 485 nanometers (nm) to 519 nanometers (nm) is mixed with the light emitted by the light-emitting diode crystal grains to enhance the color rendering of the white light-emitting diode. The cyan phosphor is a blue-green phosphor that emits (cyan) light in the wavelength range of 485 nanometers (nm) to 519 nanometers (nm) by excitation of light emitted by the light-emitting diode crystal grains. It may comprise at least one of the following fluorescent substances: LuAG: (Lu, Y) 3Al5O12: Ce, Ga-YAG: Y3 (Al, Ga) 5O12: Ce, TAG: Tb3Al5O12: Ce, (Ba, Sr, Ca) 2 SiO4 , Sr3SiO5, CaAlSiN3, (Sr, Ca, Ba, Eu) 2Si5N8-x-yOxCy, green SrSi2(O, Cl) 2N2, or yellow (Ba, Sr)Si2(O, Cl) 2N2. In general, the addition of blue-green fluorescent powder is added in the above-mentioned packaging process, but it is not limited to this. Instead, it can be selected in other process steps depending on the design, planning and requirements of the process. The addition of light powder. The amount of blue-green fluorescing powder added is about 0.01 gram or more or when the dispensing step is added. The blue-green fluorescing powder accounts for about the powder used in dispensing (ie, the phosphor glue used). The weight ratio is about 0.25%, but it can be changed according to different needs and the type of white LED produced.

The above method for enhancing the color rendering of a white light emitting diode of the present invention can be applied to various white LEDs fabricated by different techniques. For example, in a process of forming a white LED using a blue light emitting diode die and a yellow phosphor, in addition to enhancing the color rendering by the above method, it is also necessary to add a blue light emitting diode. A yellow phosphor that emits yellow light when excited by blue light, such as YAG yellow phosphor, TAG yellow phosphor, yellow silicate (SILICATE) phosphor, yellow nitride Nitride phosphor, yellow nitrous oxide Fluorescent powder, or other yellow fluorescent powder, produces white light by the complementary action of blue and yellow. Please refer to the fourth and third tables at the same time. The fourth picture shows the spectrum of white LEDs made of blue light-emitting diode crystals, yellow fluorescent powder (YAG) and blue-green fluorescent powder, while Table 3 shows this. Test results of brightness and color rendering of white LEDs.

Table 3

It can be seen from the fourth figure and the third table that the average brightness of the white LEDs prepared by adding the yellow fluorescent powder (YAG) and the blue-green fluorescent powder to the blue light-emitting diode crystal grains is about 5.9254 lm, and the average color rendering property is obtained. It is about 86.2301, and its color rendering is mostly between 84-87. Compared with the conventional white light LED (YAG) prepared by adding blue phosphorescent diode (YAG), the white LED of the present invention is indeed added with blue-green fluorescent powder (body). Reinforces the spectrum of white LEDs in the range of 485 nm (nm) to 519 nm (nm), and greatly enhances the color rendering of traditional white LEDs, enabling white LEDs to achieve high color rendering (>80 or more) Requirements. Secondly, it can be seen from Table 3 that the average brightness of the white LED is about 5.9254 lm, compared with the traditional white light LED (YAG) made of blue light emitting diode crystal (refer to the first figure and table). a) The average luminosity of 6.1505 lm, only reduced by 0.2251 lm, compared to the traditional methods of enhancing color rendering, such as adding red phosphor powder, obviously has little effect on brightness, but can increase by about 14.42% The color rendering property, therefore, the white LED produced by the method provided by the invention is obviously superior to the white LED produced by the conventional method in color rendering, and can greatly improve the color rendering of the white LED without greatly reducing the brightness. It meets the current requirements for high color rendering (>80) of white LEDs.

In another embodiment of the present invention, in a (package) process in which a blue light emitting diode die is conventionally added and a red phosphor is added and a green phosphor is used to fabricate a white light LED, a method of enhancing color rendering according to the present invention is A blue-green phosphor (powder) is added to the (package) process to reinforce the color rendering of the white LED. Wherein, the red phosphor is a red phosphor that is excited by the blue light emitted by the blue light emitting diode crystal to emit red light, such as red silicate (SILICATE) phosphor, red nitride Nitride fluorescent Powder, red oxynitride fluorescein, or other red phosphor, and the green phosphor is a green phosphor that emits green light when excited by the blue light emitted by the blue light-emitting diode crystal, for example Green silicate (SILICATE) fluorescing powder, green nitride Nitride fluorescing powder, green NOx fluorescing powder, or other green fluorescent powder. Please refer to the fifth and fourth tables at the same time. The fifth picture shows the spectrum of white LEDs made of blue light-emitting diode crystal, red fluorescent powder, green fluorescent powder and blue-green fluorescent powder, while Table 4 shows The test results of the brightness and color rendering of this white LED.

Table 4

It can be seen from the fifth and fourth tables that the average brightness of white LEDs made of blue light-emitting diode grains, red phosphor powder, green phosphor powder and blue-green phosphor powder is about 4.596395 lm, and the average The color rendering is about 89.4163, and its color rendering is mostly between 87-91. The white LED of the present invention is indeed added with blue-green fluorescent powder (compared with the second and the second) in comparison with the conventional blue light-emitting diode die (red light-emitting powder and green fluorescent powder). Reinforces the spectrum of white LEDs in the range of 485 nm (nm) to 519 nm (nm), and greatly enhances the color rendering of traditional white LEDs, which is about 14.37%, making white LEDs Achieve high color rendering (>80 or more). This white LED can even achieve nearly 90 color rendering, which is the high color rendering of the current white LED, which has created a new milestone for the color rendering of white LED. Secondly, it can be seen from Table 4 that the average brightness of the white LED is about 4.596395 lm, compared with the conventional white light LED made by adding blue fluorescent powder and green fluorescent powder to the blue light emitting diode (refer to the second figure). And the average luminosity of Table 2) is only 4.848557 lm, which is only 0.248557 lm lower. It obviously has little effect on the brightness, but it can increase the color rendering of about 14.37%. Therefore, the white LED produced according to the method provided by the present invention is obviously It is superior to the traditional method of white LED in color rendering, and can greatly improve the color rendering of white LED without greatly reducing the brightness, reaching a higher color rendering performance than the current white LED required by the industry (> 80).

In another embodiment of the present invention, in a (packaging) process in which a white LED is newly formed by adding a yellow phosphor to a white light and adding a red phosphor to enhance color rendering, The method for enhancing color rendering of the present invention adds a blue-green phosphor (powder) in the (packaging) process to further enhance the color rendering of the white LED. The yellow phosphor is a yellow phosphor that is excited by blue light emitted by the blue light emitting diode to emit yellow light, such as YAG yellow phosphor, TAG yellow phosphor, and yellow sulfate (SILICATE). Light powder, yellow nitride Nitride phosphor powder, yellow NOx phosphor powder, or other yellow phosphor powder, and the red phosphor is excited by the blue light emitted by the blue light emitting diode crystal grains. Red red phosphors, such as red silicate (SILICATE) fluorescing powder, red nitride Nitride fluorescing powder, red oxynitride fluorescing powder, or other red fluorescing powder. Please refer to the sixth figure, which is a spectrum diagram of a white LED made of blue light emitting diode crystal, yellow fluorescent powder, red fluorescent powder and blue green fluorescent powder. Similarly, as can be seen from the sixth figure, in the spectrum of the white LED, the spectrum of the white LED in the range of 485 nm (nm) to 519 nm (nm) is obviously reinforced, so that the entire white LED The color rendering is greatly and effectively enhanced.

Therefore, it can be known from the above embodiments and test data and graphs that the present invention does provide a method for effectively enhancing the color rendering of white LEDs, which only needs to add a light-receiving process in the process of fabricating white LEDs. A blue-green phosphor (powder) that emits blue-green light with a wavelength between 485 nanometers (nm) and 519 nanometers (nm), which is large and effective without transitioning the original process steps. Enhance the color rendering of white LEDs (increased by at least 14%) and have no significant effect on their brightness, while achieving high color rendering requirements (>80 or higher), and can be substantially maintained while enhancing color rendering The original brightness, unlike the traditional method of reinforcing the color rendering of white LEDs with red phosphors, changes the color of the light emitted by the white LEDs.

100, 102. . . Steps to enhance the color rendering of white LEDs

B. . . Blue light

G. . . Green light

R. . . Red light

Y. . . Huang Guang

The first picture shows the spectrum of a conventional white LED made of blue light-emitting diode crystal grains and yellow phosphor powder.

The second picture shows the spectrum of a conventional white LED made of blue light-emitting diode crystal, red phosphor and green phosphor.

The third figure is a flow chart of a method for enhancing the color rendering of a white light emitting diode according to an embodiment of the present invention.

The fourth figure is a spectrum diagram of a white light emitting diode according to an embodiment of the present invention.

Fig. 5 is a spectrum diagram of a white light emitting diode according to another embodiment of the present invention.

Figure 6 is a spectrum diagram of a white light emitting diode according to still another embodiment of the present invention.

100, 102. . . Steps to enhance the color rendering of white LEDs

Claims (16)

A method for enhancing the color rendering of a white light emitting diode, comprising:
Providing a light emitting diode die for packaging to form a white light emitting diode; and adding a blue-green phosphor in the process of packaging the light emitting diode die, and absorbing the light emitting diode die A portion of the emitted light, the light that excites the blue-green wavelength is mixed with the light emitted by the light-emitting diode die, and enhances the color rendering of the white light-emitting diode. The method for enhancing the color rendering of a white light emitting diode according to claim 1, wherein the step of encapsulating a light emitting diode die comprises the following steps:
a solid crystal, wherein the light emitting diode die is fixed on a substrate by a solid crystal glue;
Baking for curing the silver paste to fix the light emitting diode crystal grains;
a bonding wire for wire bonding the electrode of the light emitting diode die to the substrate guiding pin;
Dispensing to add a phosphor glue to form a white light emitting diode that can excite white light;
Baking to cure the encapsulant; and testing for functional testing to judge the good. The method for enhancing the color rendering of a white light emitting diode according to the first aspect of the invention, wherein the light emitting diode crystal grain is a blue light emitting diode. The method for enhancing the color rendering of a white light emitting diode according to claim 2, wherein the blue-green fluorescent system is added in the dispensing step. The method for enhancing the color rendering of a white light emitting diode according to claim 1, wherein the blue-green phosphor has a wavelength of 485 nanometers (nm) to 519 nanometers (nm). The method for enhancing the color rendering of a white light emitting diode according to claim 5, wherein the blue-green phosphor comprises at least one of the following fluorescent substances: LuAG: (Lu, Y) 3Al5O12: Ce, Ga-YAG: Y3 (Al, Ga) 5O12: Ce, TAG: Tb3Al5O12: Ce, (Ba, Sr, Ca) 2 SiO 4 , Sr 3 SiO 5 , Ca Al Si N 3 , (Sr, Ca, Ba ,Eu)2Si5N8-x-yOxCy, green SrSi2(O,Cl)2N2, or yellow (Ba,Sr)Si2(O,Cl)2N2. The method for enhancing the color rendering of a white light emitting diode according to claim 1, wherein the blue-green phosphor is added in an amount greater than 0.01 gram. The method for enhancing the color rendering of a white light emitting diode according to claim 2, wherein the amount of the blue-green phosphor added is about 0.25% of the total weight ratio of the phosphor paste. The method of enhancing the color rendering of a white light emitting diode according to the first aspect of the invention, further comprising adding a yellow phosphor in the process of encapsulating the light emitting diode, the yellow phosphor receiving the blue light The blue light emitted by the light-emitting diode excites and glows yellow. The method for enhancing the color rendering of a white light emitting diode according to claim 9, wherein the yellow phosphor is a yellow phosphor. The method for enhancing the color rendering of a white light emitting diode according to claim 9 , wherein the method further comprises adding a red phosphor in the process of encapsulating the LED, and the red phosphor receives the blue light. The blue light emitted by the light-emitting diode excites and emits red light. The method for enhancing the color rendering of a white light emitting diode according to claim 11, wherein the red phosphor is a red phosphor. The method for enhancing the color rendering of a white light emitting diode according to the first aspect of the invention, further comprising adding a green phosphor in the process of encapsulating the light emitting diode, the green phosphor receiving the blue light The blue light emitted by the light-emitting diode excites and emits green light. The method for enhancing the color rendering of a white light emitting diode according to claim 13, wherein the green phosphor is a green phosphor. The method for enhancing the color rendering of a white light emitting diode according to claim 14, wherein the method further comprises adding a red phosphor in the process of encapsulating the light emitting diode, and the red phosphor receives the blue light. The blue light emitted by the light-emitting diode excites and emits red light. The method of enhancing the color rendering of a white light emitting diode according to claim 15, wherein the red phosphor is a red phosphor.