CN213712697U

CN213712697U - LED lighting device

Info

Publication number: CN213712697U
Application number: CN202022311907.3U
Authority: CN
Inventors: 颜劲仁; 李敏; 王海蓉
Original assignee: YUNNAN OPEN UNIVERSITY
Current assignee: YUNNAN OPEN UNIVERSITY
Priority date: 2020-10-16
Filing date: 2020-10-16
Publication date: 2021-07-16
Anticipated expiration: 2030-10-16

Abstract

The utility model relates to the technical field of non-imaging optical free-form surface lighting, in particular to a LED lighting device, which comprises a substrate, an LED chip which is fixedly arranged on the substrate and the surface of which is coated with fluorescent powder, a free-form surface lens which is fixedly arranged on the substrate and is sleeved on the LED chip, and a reflector which is fixedly arranged on the substrate and is arranged around the free-form surface lens; the free-form surface lens comprises a first curved surface lens part which is annular and has an opening at the upper end, and a second curved surface lens part connected with the upper end of the first curved surface lens part; the first curved lens part is convex; the second curved lens part is concave. The utility model discloses can realize better colour homogeneity when realizing the even illumination in the angle within range of 40 ~ 60 degrees, can satisfy the illumination application field of most of reality.

Description

LED lighting device

Technical Field

The utility model relates to a non-imaging optics free-form surface illumination technical field especially relates to a LED lighting device.

Background

With the development of semiconductor LED lighting technology, LED light sources have been widely used in various lighting fields. At present, there are two main methods for realizing white light LED: one is to form a white LED light source by mixing light of three colors of red, green and blue; the other is that a blue LED light source is used for exciting YAG fluorescent powder, part of blue light can be absorbed by the YAG fluorescent powder to generate yellow light through a photoluminescence effect, and the unabsorbed blue light and the yellow light generated by excitation are mixed to form white light. The second method is widely used in the field of daily lighting due to its simple implementation and low cost.

For a white LED light source formed by blue LED and YAG fluorescent powder, because the light intensity distribution emitted by a blue LED chip is Lambert distribution, the white LED light source has the phenomenon of uneven tinting strength spatial distribution, namely more blue light at the central part, higher color temperature, more yellow light at the edge part and lower color temperature. In order to improve the color space distribution of the white light LED formed by the blue light LED + YAG phosphor, the thickness of the YAG phosphor layer is usually precisely designed to achieve good color space distribution, this method requires a better processing technique to ensure that the processing thickness of the phosphor layer is consistent with the designed thickness, the precision requirement on the production equipment is higher, and further the production cost is higher, and in practical application, the secondary optical device needs to be reused to adjust the light energy distribution of the LED, so that uniform illumination distribution can be achieved on the target surface, and the requirement of daily illumination is met.

Disclosure of Invention

The features and advantages of the present invention are set forth in part in the description which follows, or may be obvious from the description, or may be learned by practice of the invention.

In order to overcome the defect of uneven color space distribution in the traditional white light LED light source of blue light LED + YAG fluorescent powder in the prior art, the utility model provides an LED lighting device, which comprises a substrate, an LED chip which is fixedly arranged on the substrate and coated with the fluorescent powder on the surface, a free-form surface lens which is fixedly arranged on the substrate and sleeved on the LED chip, and a reflector which is fixedly arranged on the substrate and arranged around the free-form surface lens; the free-form surface lens comprises a first curved surface lens part which is annular and has an opening at the upper end, and a second curved surface lens part connected with the upper end of the first curved surface lens part; the first curved lens part is convex; the second curved lens part is concave.

Specifically, the first curved lens portion and the second curved lens portion are smoothly connected.

In particular, a high reflectivity film is also included that is applied to the reflective surface of the reflector.

Specifically, the opening angle of the reflector is 40-60 degrees;

and/or;

the reflector is a free-form surface reflector.

Specifically, the heat sink is arranged on the substrate.

The utility model has the advantages that:

1) the utility model provides a LED lighting device simple structure realizes easily, and optical device easily processes, in addition, through the primary encapsulation of free-form surface lens and reflector, can mix light and secondary grading simultaneously, has avoided in the traditional design method need respectively solitary design mix light sum secondary grading device, has reduced the complexity of system design and the figure of component, has more increased entire system's light energy utilization ratio.

2) The utility model provides a LED lighting device can realize the homogeneity of colourity and illuminance simultaneously, simple structure not only, and the space occupies for a short time, and can satisfy the lighting needs of majority, and application scope is wider.

3) The utility model discloses to the required precision of phosphor powder thickness and shape when can reduce the phosphor powder coating, reduce the technological requirement to the phosphor powder coating, and then reduce the requirement to the coating equipment precision, greatly reduced production facility cost to the production yield of LED product has been improved, thereby greatly reduced LED's manufacturing cost.

4) The utility model discloses can realize better colour homogeneity when realizing the even illumination in the angle within range of 40 ~ 60 degrees, can satisfy the illumination application field of most of reality.

Drawings

The advantages and mode of realisation of the invention will become more apparent hereinafter by describing in detail the invention with reference to the attached drawings, wherein the content shown in the drawings is only for explaining the invention, without constituting any limitation to the meaning of the invention, in which:

fig. 1 is a schematic structural diagram of an LED lighting device according to an embodiment of the present invention;

fig. 2 is a schematic diagram of a design of an LED lighting device according to an embodiment of the present invention;

fig. 3 is a schematic diagram of a free-form surface construction of an LED lighting device according to an embodiment of the present invention;

fig. 4 is a graph showing the variation of optical power distribution, relative color temperature and color coordinates corresponding to the LED light source in the embodiment of the present invention;

FIG. 5 shows an embodiment of the present invention in which a LED lighting device

The corresponding optical power distribution, the related color temperature and the color coordinate change curve at 40 ℃;

FIG. 6 shows an embodiment of the present invention in which a LED lighting device

The corresponding optical power distribution, the related color temperature and the color coordinate change curve at 50 ℃;

FIG. 7 shows an embodiment of the present invention in which a LED lighting device

The corresponding optical power distribution, the related color temperature and the color coordinate change curve at 60 degrees;

in the drawings, the corresponding relationship between the component names and the reference numbers is as follows:

the LED chip comprises an LED chip-1, fluorescent powder-2, a free-form surface lens-3, a first curved lens part-31, a second curved lens part-32, a substrate-4 and a reflector-5.

Detailed Description

The following describes embodiments of the present invention in further detail with reference to the accompanying drawings and examples. The following examples are intended to illustrate the invention, but are not intended to limit the scope of the invention.

In the description of the present invention, "a plurality" means two or more unless otherwise specified; the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "connected" and "connected" are to be interpreted broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; may be directly connected or indirectly connected through an intermediate. The specific meaning of the above terms in the present invention can be understood according to specific situations by those skilled in the art.

As shown in fig. 1, the present invention provides an LED lighting device, which includes a substrate 4, an LED chip 1 fixed on the substrate 4 and coated with phosphor 2 on the surface, a free-form lens 3 fixed on the substrate 4 and covering the LED chip 1, and a reflector 5 fixed on the substrate 4 and surrounding the free-form lens 3; the free-form surface lens 3 comprises a first curved lens part 31 which is annular and has an opening at the upper end, and a second curved lens part 32 connected with the upper end of the first curved lens part 31; the first curved lens portion 31 is convex; the second curved lens portion 32 is concave. The phosphor 2 is completely immersed inside the free-form lens 3. The free-form surface lens 3 not only protects the LED light source, but also modulates the light energy emitted by the LED light source; the light with higher color temperature emitted by the LED light source is refracted by the second curved lens part 32 and then dispersed, and the light with lower color temperature emitted by the LED light source is refracted by the first curved lens part 31 and then reflected by the reflector 5, so that a light spot with uniform illumination and chromaticity is finally formed on the target surface.

Further, the first curved lens portion 31 and the second curved lens portion 32 are smoothly connected. The first curved lens part 31 and the second curved lens part 32 are formed by rotating free curves with different radians, wherein the first curved lens part 31 is formed by rotating a first curve which is intersected with the substrate and slightly convex, the second curved lens part 32 is formed by rotating a second curve which is intersected with the optical axis and slightly concave, and the joint of the first curve and the second curve is smoothly connected to reduce the optical energy loss and avoid the influence on the refraction angle of light.

Further, a high-reflectivity film coated on the reflecting surface of the reflector 5 is also included. The reflectance of light is greatly enhanced by the high reflectance film.

Further optimize above-mentioned technical scheme, as a preferred embodiment of the utility model. The opening angle of the reflector 5 is 40-60 degrees; the aperture of the reflector 5 can be designed according to the requirements of the actual lighting application.

Further, the reflector 5 is a free-form surface reflector. The surface of the free-form surface reflector is smooth, so that the light reflection effect is ensured, and the uniformity of the illumination and the chromaticity of light spots is ensured. The free-form surface reflector can be made of metal materials or plastics.

Further, the heat sink is disposed on the substrate 4. The normal operation of the LED lighting device is ensured through the radiator, the optical device is prevented from aging, and the service life of the LED lighting device is prolonged.

Further, the LED illuminating device also comprises a circuit arranged on the substrate 4 so as to ensure the normal operation of the LED illuminating device.

Further, the material of the free-form surface lens 3 should be an optical material with good light transmittance, and may be an optical plastic such as PMMA or PC, or may be another glass material with good light transmittance, that is, the light transmittance is good, and is not limited specifically herein.

As shown in fig. 1 and fig. 2, the design principle of the LED lighting device of the present invention is as follows:

establishing a rectangular coordinate system (u, v, z) by using the LED light source as the origin of coordinates, wherein the v direction is perpendicular toThe plane faces outwards; the light ray exit angle corresponding to the connection between the first curved lens portion 31 and the second curved lens portion 32 is

The reflector 5 has an opening angle of

(u_l0,z_l0) Is the dividing point of the first curved lens and the second curved lens;

setting the light energy emitted by the LED chip 1 in the LED lighting device to be divided into two parts according to the included angle between the light ray emitted by the LED chip 1 and the optical axis

Is divided into

The situation of the time and

the case (1);

to pair

Part of the light is designed to be refracted by the second curved lens part 32 and then emitted, and is distributed with light

Within the angle range, the relationship between the incident light and the refracted light at the second curved lens part 32 is obtained; emitted from the LED chip 1 through the second curved lens part 32

Light within the angular range is dispersed to

The angle range enables the light with higher energy to be uniformly distributed on the target surface to form uniform illumination and chromaticityUniform light spots;

to pair

Part of the light is reflected by the reflector 5 after being refracted by the first curved lens part 31, so that the emergent light is distributed

In the angle range, the relationship between the incident light and the refracted light of the first curved lens part 31 and the relationship between the incident light and the reflected light of the reflector 5 after the refraction of the first curved lens part 31 are obtained; the LED chip 1 is irradiated by the first curved lens part 31 and the reflector 5

The light rays within the angle range are refracted firstly and then reflected to the target surface, so that the light energy is uniformly distributed on the target surface;

according to

The relationship between the incident light and the refracted light at the second curved lens part 32,

The relationship between the incident light and the refracted light of part of the light at the first curved lens part 31,

After partial light rays are refracted by the first curved lens part 31, discrete data points corresponding to the free-form surface lens 3 and the reflector 5 are obtained according to the relationship between incident light rays and reflected light rays on the reflector 5; according to

The relation between the incident light and the refracted light of part of the light at the second curved lens part 32 and the snell's law obtain discrete data points of the second curved lens part 32; root of herbaceous plantAccording to

Obtaining discrete data points of the first curved lens part 31 by the relation between the incident light and the refracted light of part of the light at the first curved lens part 31 and the snell's law; according to

After part of the light rays are refracted by the first curved lens part 31, the relation between incident light rays and reflected light rays on the reflector 5 and the snell's law obtain discrete data points of the reflector 5;

and constructing the free-form surface lens 3 and the reflector 5 by a curve fitting method according to discrete data points corresponding to the free-form surface lens 3 and the reflector 5 respectively.

Further, as shown in fig. 3, a method of constructing the free-form surface of the free-form surface lens 3 and the reflector 5 is as follows:

given free curve initial point P_j(u_j,z_j) According to the calculated unit vectors I of incident light and emergent light_j(I_uj,I_zj) And O_j(O_uj,O_zj) Obtaining P by Snell's law_jNormal vector N at point_j(N_uj,N_zj):

In the formula, n_IAnd n₀Respectively the refractive index of the medium in which the incident light and the emergent light are located. According to P_jNormal vector N found at point_jCan obtain P_jA straight line equation that is point and tangent to the free curve. P_j+1(u_(j+1),z_(j+1)) The coordinates of the points being rays I_j+1(I_u(j+1),I_z(j+1)) And over P_jOf straight lines which are point and tangent to the free curveAnd (4) an intersection point. Using Snell's law and P_j+1Point incident ray I_j+1(I_u(j+1),I_z(j+1)) And an emergent ray O_j+1(O_u(j+1),O_z(j+1)) In relation between them, P can be obtained_j+1Normal vector N at point_j+1(N_u(j+1),N_z(j+1)) The normal vector is also used to determine P_j+1And the equation of a straight line with the phase line of the free curve. Repeating the above steps to iteratively obtain all discrete data points P on the free-form surface_j+2,P_j+3,…,P_N。

Further optimizing the above technical solution, said

The relationship between the incident ray and the refracted ray of a part of the rays at the second curved lens portion 32 is obtained by the following specific process:

setting the light intensity distribution of the LED chip 1 to be any light intensity distribution within 0-90 degrees, and distributing light to the LED chip through the following mathematical relation (1)

Within the range of angles:

wherein,

for the light intensity distribution of the LED lighting device, the expression for the lighting system with uniform illumination is as follows:

is the light intensity distribution of the LED light source;

for the

The measurement can be performed by a photometer, and then the following polynomial fitting formula (2) is adopted for fitting:

wherein I₀As an intensity in the direction of the optical axis, i.e.

Intensity in degree, a_i(i ═ 0,1,2,3,4) is a polynomial fitting coefficient;

the following relation (5) is set according to the law of conservation of energy:

wherein,

is the angle between the incident ray and the optical axis z,

is the angle between the refracted ray and the optical axis z;

and (3) substituting the data expression fitted by the polynomial fitting formula (2) into a relational expression (5) set according to the law of conservation of energy to obtain a nonlinear equation, and solving by adopting a numerical method.

Further, the

The relationship between the incident ray and the refracted ray of a part of the rays at the first curved lens portion 31 is obtained using the following formula (3):

wherein,

is that it is

The included angle between the refracted ray after part of the ray is refracted by the first curved lens part 31 and the optical axis z;

wherein M is

The number of rays of the partial ray;

the above-mentioned

The relationship between the incident light and the reflected light at the reflector 5 after a part of the light is refracted by the first curved lens part 31 is obtained by the following specific process:

setting the light intensity distribution of the LED chip 1 to be any light intensity distribution within 0-90 degrees, and distributing light to the LED chip through the following mathematical relation (4)

Within the range of angles:

where ρ is the reflectance of the reflecting surface of the reflector 5,

is the light intensity distribution of the LED light source;

for the

wherein I₀As an intensity in the direction of the optical axis, i.e.

Intensity in degree, a_i(i ═ 0,1,2,3,4) is a polynomial fitting coefficient;

the following relation (6) is set according to the law of conservation of energy:

wherein,

the angle between the outgoing light ray from the LED chip 1 and the optical axis z,

the included angle between the reflected light ray and the optical axis z is formed by the emergent light ray emitted from the light source, refracted by the free-form surface lens 3 and reflected by the reflector 5;

and (3) substituting the data expression fitted by the polynomial fitting formula (2) into a relational expression (6) set according to the law of conservation of energy to obtain a nonlinear equation, and solving by adopting a numerical method.

Example 1

An LED light source with the average color temperature of about 5600K and the correlated color temperature change from the center to the edge of 8071K is adopted for optical design, and an illumination spot with the uniformity of illumination larger than 80% and the change of color temperature smaller than 300K is formed on a target surface. As can be seen from FIG. 4, the central region of the light emitted from the LED light source is blue compared to blueAnd the color temperature is higher, the yellow light in the edge area is more, the color temperature is lower, and the color temperature change from the central area to the edge area is more than 8000K. The light intensity distribution curve of the light source can be obtained by utilizing a curve fitting mode, and the obtained curve fitting coefficient is as follows: a0 ═ 0.9741; a1 ═ -0.5842; a2 ═ -0.02312; a3 is 0.1013; a4 ═ 0.02343. As shown in fig. 5 to 7, the LED light source model is used to design

The LED lighting devices at 40 degrees, 50 degrees and 60 degrees respectively obtain the light energy distribution, color temperature (CCT) distribution, color coordinate (x, y) distribution and light energy uniformity corresponding to the LED light source, as shown in table 1:

TABLE 1. different

Corresponding optimal energy split angle

And the corresponding calculation result:

as can be seen from the calculation results in the table, the difference is

The obtained correlated color temperature changes (delta CCT is the maximum value of the correlated color temperature-the minimum value of the correlated color temperature) are all less than 300K; the color coordinate x change (Δ x ═ x coordinate maximum-x coordinate minimum) is less than 0.01, and the color coordinate y change (Δ y ═ y coordinate maximum-y coordinate minimum) is less than 0.02; the light energy distribution uniformity on the illumination surface is more than 80%, and the calculation result meets the requirements of the related illumination standard on high chroma uniformity and uniform illumination. The utility model provides a LED lighting device and design method can realize illuminance and colourity homogeneity simultaneously on the target surface, have stronger practical application and worth.

The preferred embodiments of the present invention have been described with reference to the accompanying drawings, and those skilled in the art can implement the present invention in various modifications without departing from the scope and spirit of the present invention. For instance, features illustrated or described as part of one embodiment, can be used with another embodiment to yield a still further embodiment. The above description is only a preferred and practical embodiment of the present invention, and not intended to limit the scope of the present invention, and all equivalent changes made by using the contents of the specification and the drawings of the present invention are included in the scope of the present invention.

Claims

1. An LED lighting device is characterized by comprising a substrate, an LED chip which is fixedly arranged on the substrate and coated with fluorescent powder on the surface, a free-form surface lens which is fixedly arranged on the substrate and sleeved on the LED chip, and a reflector which is fixedly arranged on the substrate and arranged around the free-form surface lens; the free-form surface lens comprises a first curved surface lens part which is annular and has an opening at the upper end, and a second curved surface lens part connected with the upper end of the first curved surface lens part; the first curved lens part is convex; the second curved lens part is concave.

2. The LED lighting device of claim 1, wherein the first curved lens portion is smoothly connected to the second curved lens portion.

3. The LED lighting device of claim 1, further comprising a high reflectivity film applied to the reflective surface of the reflector.

4. The LED lighting device according to claim 1, wherein an opening angle of the reflector is 40-60 degrees;

and/or;

the reflector is a free-form surface reflector.

5. The LED lighting device of claim 1, further comprising a heat sink disposed on the substrate.