An LED light source for plant lighting, a preparation method and a lighting fixture

Abstract

The present invention discloses an LED light source for plant lighting, a preparation method thereof, and a lamp. The LED light source for plant lighting includes a bracket, on the surface of which there are steps, and a transparent cover is covered on the upper surface of the steps. A containing cavity is formed between the transparent cover and the bracket; blue-light LED chips and red-light LED chips connected in series or in parallel are arranged in the containing cavity; a first fluorescent glue layer is coated on the surface of the blue-light LED chips, and the first fluorescent glue layer includes a first fluorescent powder group and a first transparent glue that are fully and uniformly mixed, wherein the first fluorescent powder group emits white light under the excitation of the blue light generated by the blue-light LED chips; a second fluorescent glue layer is coated on the first fluorescent glue layer and the red-light LED chips, and the second fluorescent glue layer includes a second fluorescent powder group and a second transparent glue that are fully and uniformly mixed, wherein the second fluorescent powder group emits near-infrared light under the excitation of the blue-light and red-light LED chips.

Description

Technical Field

[0001] The present invention relates to the technical field of lighting, and more specifically, to an LED light source for plant lighting, a preparation method thereof, and a lamp equipped with the LED light source. Background Art

[0002] The light environment is one of the important physical environmental factors for plant growth and development. The effects of light on plants are mainly reflected in two aspects: on the one hand, light provides the necessary radiant energy for plant photosynthesis, which is the basis for plants to obtain energy and grow; on the other hand, light acts as a signaling molecule to regulate many physiological processes in the entire life cycle of plants, including growth, flowering, fruiting, etc. During the growth process of plants, appropriate spectral components are crucial for promoting photosynthesis and improving growth efficiency. To meet the diverse light requirements of plants at different growth stages, a comprehensive LED plant lighting solution often needs to integrate blue light, red light, and appropriate amounts of white light and infrared light. Blue light in the range of 400 - 450 nm is beneficial for plants to form anthocyanins and inhibit the growth of branches and leaves; red light in the range of 650 - 660 nm promotes the overall growth of plants, especially during the flowering and fruiting periods, increasing the growth rate, the number of fruits, and reducing the incidence of deformed fruits. Near-infrared light around 730 nm has a positive promoting effect on plant growth, such as regulating the plant growth cycle, promoting seed germination, and regulating seedling morphology.

[0003] Currently, the light source of commonly used LED plant growth lights in the market is an LED surface mount lamp bead, and each lamp bead seals a chip to excite the phosphor to obtain a single light source. For example, a white LED light source obtained by exciting the phosphor with a 450 nm blue LED chip, an LED light source that directly emits red light with a 660 nm red LED chip, and an LED light source that directly emits near-infrared light with a 730 nm chip. The light source formed by mixing multiple such light sources has drawbacks such as poor light emission uniformity and serious scattering phenomenon, resulting in uneven illumination surfaces, uneven light reception by plants, and uneven growth surfaces. At the same time, a large amount of light is scattered, causing energy consumption waste. In addition, limited by chip materials and technical levels, the potential for improving the photoluminescence quantum efficiency of 730 nm chips is limited, and its price is 10 to 20 times that of 450 nm chips, exacerbating the pressure on the preparation cost. Summary of the Invention

[0004] The present invention proposes an LED light source for plant lighting, aiming to solve the problem in the prior art that the light emission uniformity of plant growth lights is poor and not conducive to use. In addition, while solving the current problem of light source uniformity of plant lights, the photosynthetic photoluminescence quantum efficiency of the LED light source is greatly improved.

[0005] To achieve the above technical purpose, the present invention adopts the following technical solutions:

[0006] An LED light source for plant lighting, comprising a bracket, on the surface of which there are steps, and a transparent cover is covered on the upper surface of the steps, and a containing cavity is formed between the transparent cover and the bracket; blue light LED chips and red light LED chips connected in series or parallel, which are arranged in the containing cavity; a first fluorescent glue layer is coated on the surface of the blue light LED chips, and the first fluorescent glue layer includes a first phosphor group and a first transparent glue which are fully and uniformly mixed, wherein the first phosphor group emits white light under the excitation of the blue light generated by the blue light LED chips; a second fluorescent glue layer is coated on the first fluorescent glue layer and the red light LED chips, and the second fluorescent glue layer includes a second phosphor group and a second transparent glue which are fully and uniformly mixed, wherein the second phosphor group emits near-infrared light under the excitation of the blue light and red light LED chips.

[0007] Preferably, the first phosphor group includes a green phosphor with an emission peak wavelength of 500-550 nm and a red phosphor with an emission peak wavelength of 600-660 nm; the second phosphor group includes a near-infrared phosphor with an emission peak wavelength of 700-750 nm.

[0008] Preferably, the first phosphor group includes a green phosphor with an emission peak wavelength of 530-540 nm and a red phosphor with an emission peak wavelength of 620-630 nm; the second phosphor group includes a near-infrared phosphor with an emission peak wavelength of 710-730 nm.

[0009] Preferably, the emission peak wavelength of the blue light LED chips is 430-460 nm, and the emission peak wavelength of the red light LED chips is 620-660 nm.

[0010] Preferably, the emission peak wavelengths of the blue light LED chips are a combination of 435-440 nm, 445-450 nm, and 455-460 nm, and the emission wavelength of the red light LED chips is 655-660 nm.

[0011] Preferably, the radiation intensity ratio of the emission peak wavelengths of the blue light LED chips of 435-440 nm, 445-450 nm, and 455-460 nm is 1:(0.95-0.99):(0.90-0.94).

[0012] Preferably, the light radiation power ratio of the blue light LED chips and the red light LED chips is 1:(3-9).

[0013] Preferably, the proportion of the first phosphor group in the first fluorescent glue layer is 15-50%, and the proportion of the first transparent glue is 50-85%; and the lower the color temperature, the higher the proportion of the first phosphor group; the ratio of the second phosphor group and the second transparent glue in the second fluorescent glue layer is 1:(10-20).

[0014] Preferably, the transparent cover is a silicone lens, and the refractive index ratio of the silicone lens to the refractive index of the second transparent adhesive is (1.01 - 1.03):1.

[0015] The present invention also proposes a method for preparing the above-mentioned LED light source for plant lighting, including the following steps: Step 1, encapsulating series-connected or parallel-connected blue LED chips and red LED chips on the upper surface of the bracket; Step 2, preparing a first fluorescent adhesive layer, fully mixing the first phosphor group with the first transparent adhesive; coating the first fluorescent adhesive on the blue LED chips; Step 3, preparing a second fluorescent adhesive layer, fully mixing the second phosphor group with the second transparent adhesive; uniformly coating the second fluorescent adhesive below the step of the bracket to cover the first fluorescent adhesive layer and above the red LED chips; Step 4, dotting or molding a transparent cover on the upper surface of the step of the bracket.

[0016] In addition, the present invention also proposes a plant lighting fixture, which includes the above-mentioned LED light source for plant lighting.

[0017] Due to the adoption of the above technical solutions, the advantages of the present invention are as follows:

[0018] 1. By coupling phosphor to encapsulate blue LED chips and red LED chips into the same LED light source, the uniform distribution of spectral components is achieved, avoiding the problem of uneven distribution of spectral components in traditional plant lighting fixtures.

[0019] 2. The design of using infrared phosphors to replace infrared chips reduces the production cost of the fixture, further enriches the spectral components, and improves the comprehensive efficiency of the plant lighting fixture.

[0020] 3. The LED plant lighting source of the present invention greatly improves the photosynthetic photon efficiency of the light source on the premise of ensuring spectral uniformity by optimizing the encapsulation structure, optimizing the chip wavelength and optical power, and optimizing the phosphor ratio.

[0021] Therefore, the LED light source of the present invention has a very wide application prospect in plant lighting. Description of the Drawings

[0022] Figure 1 Shown is a schematic structural diagram of the LED light source for plant lighting in the embodiment;

[0023] Figure 2 Shown is a flowchart of the preparation method of the LED light source for plant lighting in the embodiment;

[0024] Figure 3 Shown is the spectral diagram of the LED light source in the first embodiment, with the abscissa being the wavelength and the ordinate being the light intensity; Detailed Embodiments

[0025] The technical solution of the present invention will be further specifically described below through embodiments in conjunction with the accompanying drawings.

[0026] Referring to Figure 1 As shown, the LED light source for plant lighting in this embodiment includes a bracket 1, a blue light LED chip 2, a red light LED chip 3, a first fluorescent glue layer 4, a second fluorescent glue layer 5, and a transparent cover 6.

[0027] The bracket 1 serves as a support for encapsulation. A step 11 is provided on the surface of the bracket 1, and the transparent cover 6 is covered on the upper surface of the step 11 to achieve sealing. A receiving cavity is formed between the cover 6 and the bracket 1. The blue light LED chip 2 and the red light LED chip 3 are arranged in the receiving cavity in series or in parallel and are electrically connected to an external power supply. The first fluorescent glue layer 4 is coated on the blue light LED chip 2, and the second fluorescent glue layer 5 is coated on the first fluorescent glue layer 4 and the red light LED chip 3.

[0028] The bracket 1 can be made of PPA, PCT, and EMC materials. Among them, PCT and EMC are better, with fast heat dissipation. In one embodiment, an EMC bracket is selected, which has fast heat dissipation and can increase the light output efficiency. The EMC bracket can be used for higher power, which is beneficial to encapsulating multiple chips. By adjusting the number and ratio of the blue light LED chip 2 and the red light LED chip 3, the spectrum and photosynthetic photon efficiency (PPE) can be adjusted.

[0029] In one embodiment, the emission wavelength of the blue light LED chip 2 is 430 - 460 nm, and the emission wavelength of the red light LED chip 3 is 620 - 660 nm. These two bands have the strongest effect on plant photosynthesis. Preferably, the peak wavelength of the emission wavelength of the blue light LED chip 2 is a combination of 435 - 440 nm, 445 - 450 nm, and 455 - 460 nm, and the emission wavelength of the red light LED chip 3 is 655 - 660 nm. The radiation intensity ratio of the peak wavelengths of the emission wavelength of the blue light LED chip 2 at 435 - 440 nm, 445 - 450 nm, and 455 - 460 nm is 1:(0.95 - 0.99):(0.90 - 0.94). The blue light LED chip 2 can achieve a higher photosynthetic photon efficiency (PPE) by regulating the epitaxy to achieve a combination of multiple peak bands to excite the phosphor. The optimized peak combination has a higher PPE.

[0030] Preferably, the light radiation power ratio of the blue light LED chip 2 and the red light LED chip 3 is 1:(3 - 9). This ratio is to optimize the entire spectrum and PPE. If the ratio is too small, the red light is too strong and the white light spectral component is too low, which is not suitable for the needs of plant cultivation; if the ratio is too high, the white light is too strong and the PPE value is too low.

[0031] The first fluorescent glue layer 4 includes a first phosphor group and a first transparent glue that are fully and evenly mixed, and the first phosphor group emits white light and near-infrared light under the excitation of the blue light. The first fluorescent glue layer 4 is evenly coated on the surface of the blue LED chip 2, and the second fluorescent glue layer 5 can be dot-coated on the step surface of the bracket 1, the first fluorescent glue layer 4, the red LED chip 3, and the inner surface of the cover.

[0032] In the second fluorescent glue layer 5, the ratio of the second phosphor to the second transparent glue is 1:(10 - 20). If this ratio is too high, the far-red light intensity is too low to achieve the planting effect; if the ratio is too low, the proportion of the infrared phosphor is too large, which will cause serious absorption of white light and red light, thereby reducing the PPE of the entire light source.

[0033] In one embodiment, the first phosphor group includes a green phosphor with an emission peak wavelength in the range of 500 - 550 nm, a red phosphor with an emission peak wavelength in the range of 600 nm - 660 nm, a second phosphor group, and a near-infrared phosphor with an emission peak wavelength in the range of 710 nm - 730 nm. The chemical formula of the green phosphor is at least one of Y3(Al, Ga)5O12:Ce3+ and Lu3Al5O12:Ce3+; the red phosphor is at least one of (Sr, Ca)AlSiN3:Eu2+ and Sr2Si5N8:Eu2+; the chemical formula of the near-infrared phosphor is at least one of Y3Al5O12:Cr3+ and Lu3Si5N11:Cr. The first phosphor group emits white light under the excitation of the blue light generated by the blue LED chip.

[0034] In another embodiment, the first phosphor group includes a green phosphor with an emission peak wavelength in the range of 530 - 540 nm and a red phosphor with an emission peak wavelength of 620 nm - 630 nm; the second phosphor group includes a near-infrared phosphor with an emission peak wavelength in the range of 710 nm - 730 nm.

[0035] In the first fluorescent glue 41, the proportion of the first phosphor group is 15 - 50%, and the proportion of the first transparent glue is 50 - 85%; and the lower the color temperature, the higher the proportion of the first phosphor group; in the second fluorescent glue, the ratio of the second phosphor group to the second transparent glue is 1:(10 - 20). The proportion of the phosphor can be adjusted according to the color temperature range. Usually, the color temperature range is between 2700 K and 7500 K, and the lower the color temperature, the higher the proportion of the phosphor.

[0036] The transparent cover 6 is a silica gel lens, and the refractive index ratio of the silica gel lens to that of the second transparent adhesive is (1.01 - 1.03):1. The main purpose of setting this refractive index ratio is to further improve the PPE of the device, mainly by optimizing the refractive index between the silica gels, thereby extracting more outgoing light and reducing the losses caused by light scattering and refraction. If the ratio is too low, the improvement of PPE is not obvious. If the ratio is too high, it is not conducive to the stability of the device at high temperatures and is likely to cause delamination or cracking of the silica gel.

[0037] The LED light source for plant lighting provided by the present invention generates white light components by exciting green phosphor and red phosphor with the blue light emitted by the blue LED chip 2. As the basic light source for plant photosynthesis, the uniform distribution of white light is crucial for the overall growth of plants. The blue LED chip 2 can also excite near-infrared phosphor to generate near-infrared components beneficial to plants, further enriching the spectral components and improving the comprehensive efficiency of the plant supplementary light. The red LED chip 3 directly emits red light to increase the red light component of the spectrum, and this red light component has a significant effect on promoting plant photosynthesis and flowering and fruiting. Since the red LED chip 3 and the blue LED chip 2 are encapsulated in the same light source, the red light can be more evenly distributed on the plant surface, avoiding the problems caused by the too large spacing of the red light sources in traditional supplementary lights. The LED light source of the present invention realizes the uniform distribution of spectral components by encapsulating the blue LED chip 2 and the red LED chip 3 in the same LED light source, avoiding the problem of uneven distribution of spectral components in traditional plant lighting fixtures. The design of replacing the infrared chip with infrared phosphor reduces the production cost of the lighting fixture, further enriches the spectral components, and improves the comprehensive efficiency of the plant lighting fixture.

[0038] First Embodiment: An LED light source for plant lighting, comprising a bracket, on the surface of which there are steps, and a transparent cover is covered on the upper surface of the steps, and a receiving cavity is formed between the transparent cover and the bracket; a series-connected blue LED chip (wavelengths are 437nm, 445nm, 457nm, and the blue light intensity ratio is 1:0.96:0.92) and a red LED chip (peak wavelength 657nm), which are arranged in the receiving cavity; a first fluorescent glue layer is coated on the surface of the blue LED chip, and the first fluorescent glue layer includes a first phosphor group and a first transparent glue that are fully and evenly mixed, wherein the phosphor wavelengths of the first phosphor group are a green phosphor of 525nm and a red phosphor of 625nm, and white light is emitted under the excitation of the blue light generated by the blue LED chip; a second fluorescent glue layer is coated on the first fluorescent glue layer and the red LED chip, and the second fluorescent glue layer includes a second phosphor group and a second transparent glue that are fully and evenly mixed, wherein the second phosphor group is a phosphor with a peak wavelength of 725nm, and near-infrared light is emitted under the excitation of the blue and red LED chips. The radiation power ratio of the blue chip to the red chip is 1:3, and the refractive index ratio of the silica gel lens to the second transparent glue is 1.02:1. See Figure 3 , the wavelength-light intensity chart of the LED light source for plant lighting in this embodiment.

[0039] In order to further illustrate the technical effects of the LED light source of the present invention, the following is a comparison through specific examples and comparative examples:

[0040] Examples 1-8, Comparative Examples 1-4: An LED light source for plant lighting, the specific preparation method thereof is as above, and the relevant parameters such as the specific chip wavelength and radiation power ratio are shown in Table 1.

[0041] Comparative Example 5: A plant light source, specifically including two light sources of white light and red light, and the spectrum realized by their mixing is the same as that of Example 4, and the parameters under the same power are shown in Table 2.

[0042] Table 1

[0043]

[0044]

[0045] Table 2

[0046]

[0047]

[0048] Note: The uniformity of the spectrum refers to the uniformity of the spectrum during different tests of the lamp, including comprehensive references such as brightness and spectral changes; the balance of the spectrum refers to the proportional coordination of various visible spectra when growing plants; the photoquantum efficiency of the lamp refers to the PPE value tested by a 100W lamp strip.

[0049] As can be seen from Table 1 and Table 2, using different wavelength bands of blue light and optimizing different ratios helps to improve the photoquantum efficiency of the light source and the lamp; when the red-blue ratio is in the range of 1:(3 - 9), it can be compatible with both spectral balance and photoquantum efficiency. If the ratio is too high, the photoquantum efficiency is too low, and if the ratio is too low, the spectral balance is too poor; when the refractive index ratio of the silica gel lens to the second transparent adhesive is (1.01 - 1.03):1, it can take into account the stability of the device and the photoquantum efficiency. If the ratio is too low, the improvement of the photoquantum efficiency is not obvious, and if the ratio is too high, the light decay of the device is too large and it is prone to failure.

[0050] Participate Figure 2 As shown, the present invention also provides a method for preparing the above-mentioned LED light source for plant lighting, including the following steps:

[0051] Step S1, encapsulate the series-connected or parallel-connected blue LED chips and red LED chips on the upper surface of the bracket;

[0052] Step S2, prepare a first fluorescent glue layer, and fully mix the first phosphor group with the first transparent adhesive; coat the first fluorescent glue on the blue LED chips;

[0053] Step S3, prepare a second fluorescent glue layer, and fully mix the second phosphor group with the second transparent adhesive; evenly coat the second fluorescent glue below the step of the bracket to cover the first fluorescent glue layer and above the red LED chips;

[0054] Step S4, dot or mold a transparent cover on the upper surface of the step of the bracket.

[0055] In addition, the present invention also provides a plant lighting lamp, and the lamp includes the above-mentioned LED light source for plant lighting. The plant lighting LED lamp of the present invention has a simple structure, is easy to manufacture and maintain, and is suitable for the growth environment of various plants. Therefore, the LED light source of the present invention has a very wide application prospect in plant lighting.

[0056] The above-described embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. Equivalent changes and modifications made by those skilled in the art to the present invention shall fall within the scope covered by the appended claims of the present invention.

Claims

1. An LED light source for plant lighting, characterized in that, including a bracket, on the surface of which there are steps, and a transparent cover is covered on the upper surface of the steps, and an accommodating cavity is formed between the transparent cover and the bracket; series-connected or parallel-connected blue light LED chips and red light LED chips, which are arranged in the accommodating cavity; a first fluorescent glue layer is coated on the surface of the blue light LED chip, and the first fluorescent glue layer includes a first fluorescent powder group and a first transparent glue which are fully and evenly mixed, wherein the first fluorescent powder group emits white light under the excitation of the blue light generated by the blue light LED chip; a second fluorescent glue layer is coated on the first fluorescent glue layer and the red light LED chip, and the second fluorescent glue layer includes a second fluorescent powder group and a second transparent glue which are fully and evenly mixed, wherein the second fluorescent powder group emits near-infrared light under the excitation of the blue light and red light LED chips; 2. The LED light source for plant lighting according to claim 1, wherein, the first fluorescent powder group includes a green fluorescent powder with an emission peak wavelength of 500-550 nm and a red fluorescent powder with an emission peak wavelength of 600-660 nm; the second fluorescent powder group includes a near-infrared fluorescent powder with an emission peak wavelength of 700-750 nm; 3. The LED light source for plant lighting according to claim 1, wherein the first fluorescent powder group includes a green fluorescent powder with an emission peak wavelength of 530-540 nm and a red fluorescent powder with an emission peak wavelength of 620-630 nm; the second fluorescent powder group includes a near-infrared fluorescent powder with an emission peak wavelength of 710-730 nm; 4. The LED light source for plant lighting according to claim 1, characterized in that, the emission peak wavelength of the blue light LED chip is 430-460 nm, and the emission peak wavelength of the red light LED chip is 620-660 nm; 5. The LED light source for plant lighting according to claim 4, wherein the emission wavelength peak wavelength of the blue light LED chip is a combination of 435-440 nm, 445-450 nm, and 455-460 nm, and the emission wavelength of the red light LED chip is 655-660 nm; 6. The LED light source for plant lighting according to claim 5, wherein the radiation intensity ratio of the emission wavelength peak wavelength of the blue light LED chip of 435-440 nm, 445-450 nm, and 455-460 nm is 1:(0.95-0.99): (0.90-0.94)。 7. The LED light source for plant lighting according to claim 4, wherein the light radiation power ratio of the blue light LED chip and the red light LED chip is 1:(3-9); 8. The LED light source for plant lighting according to claim 1, characterized in that, the proportion of the first fluorescent powder group in the first fluorescent glue layer is 15-50%, and the proportion of the first transparent glue is 50-85%; and the lower the color temperature, the higher the proportion of the first fluorescent powder group; the ratio of the second fluorescent powder group and the second transparent glue in the second fluorescent glue layer is 1:(10-20); 9. The LED light source for plant lighting according to claim 1, characterized in that, the transparent cover is a silica gel lens, the refractive index ratio of the silica gel lens to the refractive index of the second transparent glue is (1.01-1.03):1; 10. A method for preparing an LED light source for plant lighting according to any one of claims 1-9, characterized in that, including the following steps: Step 1, encapsulate series-connected or parallel-connected blue light LED chips and red light LED chips on the upper surface of the bracket; Step 2, prepare a first fluorescent glue layer, fully mix the first fluorescent powder group and the first transparent glue; coat the first fluorescent glue on the blue light LED chip; Step 3: Provide a second fluorescent glue layer, and fully mix the second phosphor group with the second transparent glue; uniformly coat the second fluorescent glue below the step of the bracket to cover the first fluorescent glue layer and above the red LED chip; Step 4: Dot-apply or mold a transparent cover on the upper surface of the step of the bracket.

11. A plant lighting fixture, characterized in that, The lamp includes the LED light source for plant lighting according to any one of claims 1-9.

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