CN101586779A - Design method of LED homogeneous reflector based on optical extension and use thereof - Google Patents

Abstract

The invention discloses a design method and application of an LED uniform reflector based on etendue. According to the analysis of the luminous characteristics of the LED light source and the illumination requirements of a specific target plane, the etendue conservation theory in non-imaging optics is used to establish a reflection reflector. The general mathematical model of the device, the reflective surface is a curved surface determined by the rotation of the curve defined by the curve equation described in the specification. Uniform illumination can be achieved by using a single reflector, and high illumination uniformity and energy utilization efficiency are obtained on the target plane. The design method of the uniformly illuminated reflector of the present invention can be used in systems requiring high uniform illumination, such as in microscope illumination systems, indoor illumination, projection systems and other illumination systems using LEDs as light sources. It can not only simplify the structure of the system but also increase the utilization rate of light energy, and the uniformity of illuminance is also greatly improved. Therefore the present invention has very good application prospect.

Description

Design method and application of LED uniform illumination reflector based on etendue

technical field

The invention relates to LED lighting technology, in particular to a design method of a uniform lighting reflector and a reflector obtained by the design method.

Background technique

With the development of semiconductor lighting technology, LED, as a new artificial light source, has shown a very broad application prospect due to its small size, low energy consumption, good monochromaticity and other advantages. LEDs are gradually replacing traditional light sources and becoming a new generation of light sources. However, there are still many deficiencies in LEDs at present. The total luminous energy of a single LED is low, and most LED products have a Lambertian distribution luminous curve with a large divergence angle, so they cannot be used alone in lighting systems. In most applications, People need additional optical elements to cooperate with LEDs to achieve uniform illumination within a certain range.

In the prior art, there are secondary reflective concentrators mentioned in patent documents with publication numbers CN1948823A and CN2760613Y and optical rods for uniform light. There are also methods such as adopting reflective compound eyes or transmissive fly eyes for uniform light as mentioned in the patent documents whose publication numbers are CN1554983A and CN2891006Y.

However, although these methods based on traditional imaging optics have solved the problem of uniform illumination within a certain range, due to the limitations of their own nature, there is a certain collection angle, so they cannot achieve the purpose of high utilization of LED light energy. The effect of uniform light is good for a long enough time, but it wastes energy at the cost of sacrificing the utilization rate of light energy. At the same time, the whole system is more complicated. Today, as miniaturization is increasingly becoming the trend, the uniformity limitations of traditional lighting systems are becoming more and more obvious.

Some people also use non-imaging optical theory to achieve uniform illumination design. For example, J.M.Gordon and Ari Rabl use TEDs (Tailored Edge-ray Device) design method to design axisymmetric reflectors to achieve uniform illumination in the far field. Ding Yi et al. established partial differential equations based on catadioptric equations and energy conservation, and obtained free-form surface lenses and free-form surface reflectors for uniform illumination through numerical solutions. However, this method is cumbersome for the design of rotationally symmetric reflectors. .

In addition, with the application of three-dimensional aided design, more and more reflector structures are expressed by equations, and then realized in industrial production through three-dimensional aided design. For example, a backlight system and its reflector are disclosed in Chinese invention patent 200510037129.0, including A plurality of light sources, a reflector and a light guide plate, the light guide plate includes a light incident surface, a light exit surface connected to the light incident surface and a bottom surface opposite to the light exit surface, the light source is arranged opposite to the light incident surface, and the reflector There are a plurality of reflection units, the plurality of reflection units respectively accommodate the plurality of light sources, each reflection unit has two opposite reflection surfaces, the two reflection surfaces are opposite to the light incident surface and the cross-sectional shape of the two reflection surfaces is Defined by a specific equation in a polar coordinate.

However, the combined structure of the reflector and the light guide plate in the prior art is too complicated and inconvenient to process. Although some optical transmission devices are used to solve the problem of uniform illumination, the optical transmission device consumes a part of energy, and the energy utilization rate is very low.

Contents of the invention

According to the characteristics of the LED light source and the distribution requirements of the illuminance of the target plane, and based on the etendue conservation theory in non-imaging optics, the invention provides a reflector design method with uniform illumination and simple structure.

A design method of LED uniform illumination reflector based on etendue, comprising:

(1) Establish a polar coordinate system with the LED light source as the origin,

(2) Determine the target area to be illuminated at the opposite direction of the beam emission of the LED light source;

(3) Use the following curve equation to establish the reflective surface curve at the positive direction of the beam emission of the LED light source,

$\frac{\mathrm{<span\; class="notranslate">\; dr</span>}}{\mathrm{<span\; class="notranslate">\; d\&theta;</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; the\; tan</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; arctan</span>}\frac{\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}}{\mathrm{<span\; class="notranslate">\; sin</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}}\mathrm{<span\; class="notranslate">\; R</span>}}{\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>$

In the formula:

r is the distance between the center of the light-emitting surface of the LED light source and any point P on the reflective surface;

θ is the angle between the light emitted from the center of the light-emitting surface of the LED light source to any point P on the reflective surface and the normal line of the light-emitting surface of the LED light source;

θ _max is the maximum divergence angle of the output beam of the light-emitting surface of the LED light source;

_x0 is the distance between the lighting target plane and the center of the LED light emitting surface;

R is the radius of the illumination area on the target plane;

(4) Rotating the reflective surface curve around the normal line of the center of the light-emitting surface of the LED light source to obtain the reflective surface of the LED uniform illumination reflector based on etendue.

In the design method of the present invention, the illumination range R and the position _x0 of the target surface relative to the LED light source are taken as structural parameters of the equation. Since different lighting ranges R and different positions x ₀ can be selected according to specific lighting requirements, the application range of the design method is expanded.

When performing design calculations, you can:

a) Select the polar radius r of the initial point as the distance r ₀ from the center vertex of the reflector to the center of the light-emitting surface of the LED light source, θ starts at 0°, and ends at θ _max as the end point;

Or b) select the initial point from the semi-diameter h of the reflector, the polar radius r ₀ =h/sinθ _max at this time, the polar angle is θ _max , and end when θ is 0°.

The LED light source in the present invention can be light-emitting diodes (LEDs) of various powers and colors. The light intensity distribution of the LED has a Lambertian or Lambertian-like distribution. The reflectivity of the reflector can be a commonly used reflective film.

The LED light source emits light toward the reflective surface coated with reflective film. After reflection, almost all the light can reach the target plane, which improves the utilization rate of light energy and the uniformity of illuminance.

The present invention also provides an etendue-based LED uniform lighting reflector obtained by using the design method, including an LED light source and a reflector for reflecting light emitted by the LED light source to a target plane that needs to be illuminated. The two-dimensional profile curve of the reflector is defined by the following equation:

$\frac{\mathrm{<span\; class="notranslate">\; dr</span>}}{\mathrm{<span\; class="notranslate">\; d\&theta;</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; the\; tan</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; arctan</span>}\frac{\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}}{\mathrm{<span\; class="notranslate">\; sin</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}}\mathrm{<span\; class="notranslate">\; R</span>}}{\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>$

In the formula:

r is the distance between the center of the light-emitting surface of the LED light source and any point P on the reflective surface

θ is the angle between the light emitted from the center of the light-emitting surface of the LED light source to any point P on the reflective surface and the normal line of the light-emitting surface of the LED light source;

θ _max is the maximum divergence angle of the output beam of the light-emitting surface of the LED light source;

_x0 is the distance between the lighting target plane and the center of the LED light emitting surface;

R is the radius of the illumination area on the target plane;

The curved surface mentioned above is a curve determined by the above curve equation, which is formed by rotating around the normal line of the center of the light-emitting surface of the LED light source.

The reflective surface can be made of general reflective materials in the prior art, and the reflective surface is concave, which expands the light energy of the LED light source to the surroundings, so that the energy distribution is uniform. The LED light source emits light toward the reflective surface. After reflection, almost all the light can reach the target plane, which improves the utilization rate of light energy and the uniformity of illumination.

Etendue is an important concept in non-imaging optics theory (see W.Cassarly. "Non-imaging Optics: Concentration and Illumination," OSA Handbook of Optics, ^2nd edition, Vol 3.Chap 2.McGraw-Hill, New York (2001).), describing the integral of the area passed by the beam and the solid angle occupied by the beam, which is used to weigh the required area and solid angle, determine the energy collection rate of the system, and then determine the structural parameters. Etendue is defined as:

U＝n ² ∫∫cos θdAdΩ(1)

In the formula, n is the refractive index, and θ is the angle between the normal of the microelement area dA and the central axis of the microelement solid angle dΩ.

For an ideal optical system, without considering losses such as refraction, reflection, scattering, and absorption, the etendue is conserved after the beam passes through the optical system. Etendue matching is the most important consideration in the design of non-imaging optical systems. The smaller the etendue of the light source, the better, and the larger the etendue of the optical element, the better. However, an increase in the amount of expansion does not necessarily lead to an increase in energy efficiency to the same degree, and it also causes an increase in system complexity and cost. Therefore, it is necessary to reasonably design the lighting system, control the light direction, and realize the matching of the etendue, so as to obtain a higher light energy utilization rate and the required lighting uniformity.

The LED uniform illumination reflector based on etendue of the present invention is designed based on the theory of etendue conservation in the non-imaging optical theory, that is, in an ideal optical system, without considering losses such as refraction, reflection, scattering, and absorption In this case, the etendue is conserved after the beam passes through the optical system. The smaller the etendue of the light source, the better, and the larger the etendue of the optical element, the better. However, an increase in the amount of expansion does not necessarily lead to an increase in energy efficiency to the same degree, and it also causes an increase in system complexity and cost. Therefore, it is necessary to reasonably design the lighting system, control the light direction, and realize the matching of the etendue, so as to obtain a higher light energy utilization rate and the required lighting uniformity.

According to the analysis of the luminous characteristics of the LED light source and the illumination requirements of a given target plane, and according to the etendue conservation theory in non-imaging optics, the present invention establishes a general mathematical model of the reflector, and uniform illumination can be realized by using a single reflector , and higher uniformity of illumination and energy utilization can be obtained on the target plane. The design method of the uniformly illuminated reflector of the present invention can be used in systems requiring high uniform illumination, such as in microscope illumination systems, indoor illumination, projection systems and other illumination systems using LEDs as light sources. It can not only simplify the structure of the system but also increase the utilization rate of light energy, and the uniformity of illuminance is also greatly improved. Therefore, the design method of the present invention has a good application prospect.

Description of drawings

Fig. 1 is that the light intensity distribution of light-emitting diode that the present invention adopts has the light intensity distribution figure of Lambertian characteristic,

The abscissa in the figure is the θ angle, and the ordinate is the normalized light intensity;

Fig. 2 is the schematic diagram of the principle of the reflector of the present invention;

Fig. 3 is the reflector model figure that the reflector of the present invention is used in microscope illumination system;

Fig. 4 is the simulation diagram of the microscope illumination system in Fig. 3;

Fig. 5 is the illuminance distribution diagram in the lighting area;

Figure 6 is the illuminance distribution curve in the horizontal and vertical directions; line A in the figure represents the illuminance distribution curve in the vertical direction; line B represents the illuminance distribution curve in the horizontal direction;

Detailed ways

The design method of the present invention is based on the analysis of the luminous characteristics of the LED light source and the specific target plane illumination requirements, and applies the etendue conservation theory in non-imaging optics to establish a general mathematical model of the reflector, and use a single reflector to achieve uniform illumination. And higher illumination uniformity and energy utilization rate can be obtained on the target plane.

Using etendue correlation theory, see Figure 2, establish a polar coordinate system, the center of the light-emitting diode light-emitting surface is placed at the origin (0, 0) of the coordinate system, and the normal of the light-emitting surface is along the negative direction of the x-axis. In polar coordinates, the differential equation of the profile of the reflective surface is:

$\frac{\mathrm{<span\; class="notranslate">\; dr</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; the\; tan</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; d\&theta;</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

In the formula, θ is the angle between the light emitted from the center of the LED light source to any point P of the reflector and the normal line of the light-emitting surface of the LED.

According to Figure 2, it can be obtained

$\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; arctan</span>}\frac{\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}}{\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

In the formula, x ₀ is the distance between the center of the light-emitting diode and the target plane, which can be selected according to the location of the lighting plane. y is the position where the light falls on the target plane after being reflected by point P. In the formula (1), n=1, then for the light reflected from any taper θ of the LED light source, it can be obtained

In the formula, U _s is the etendue of the light source in θ, and A _s is the light-emitting area of the LED light source. Obtain the illuminance on the target plane corresponding to the θ angle by calculation

${\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; LU</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}}{{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$

In the formula, L is the brightness of the illuminating surface, A _t is the illuminating area on the target plane, and U _t is the etendue on the target plane. In addition, the illuminance of the boundary point is

${\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; LU</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}{{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 6</span>}<span\; class="notranslate">\; )</span>$

According to the etendue conservation and iso-illuminance conditions

U _s =U _t

(7)

E _t =E ₀

get,

$\frac{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; 0</span>}}}{{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 8</span>}<span\; class="notranslate">\; )</span>$

U _s0 is the etendue corresponding to θ _max . Substituting A _t = πy ² , A ₀ = πR ² , U _s = πA _s sin ² θ, U _s0 = πA _s sin ² θ _max into formula (8), we get

$\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}}{\mathrm{<span\; class="notranslate">\; sin</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}}\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 9</span>}<span\; class="notranslate">\; )</span>$

In the formula, R can be designed according to the needs of the illuminated target plane, and R is the radius of the illuminated area. Substitute formula (9) and formula (3) into formula (2) to get formula (10),

$\frac{\mathrm{<span\; class="notranslate">\; dr</span>}}{\mathrm{<span\; class="notranslate">\; d\&theta;</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; the\; tan</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; arctan</span>}\frac{\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}}{\mathrm{<span\; class="notranslate">\; sin</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}}\mathrm{<span\; class="notranslate">\; R</span>}}{\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 10</span>}<span\; class="notranslate">\; )</span>$

It can be seen from the formula (10) that the discrete point coordinates of r and θ can be obtained by numerical integration method. These discrete points form a curve, and the curve rotates around the normal line of the center of the light emitting surface of the LED light source to obtain a surface composed of three-dimensional data points (which can be Use 3D modeling software to perform surface fitting) to obtain the reflective surface of the reflector.

Use the above design method to manufacture the reflector, take the LED light source as the origin, the distance _r0 from the center vertex of the reflector to the center of the light-emitting surface of the LED light source is 5mm, the target plane position _x0 is 15mm, and the radius R of the illumination range is 45mm. The size of the light source is 1 mm×1 mm, the divergence angle θ _max of the LED light source is 90°, the luminous flux is set to 10 lm, and the reflectance of the reflector is set to 1.

The LED light source adopts light-emitting diodes with Lambertian characteristics of light intensity distribution. The light intensity distribution diagram can be seen in Figure 1. The abscissa in Figure 1 is the θ angle, and the ordinate is the normalized light intensity.

According to above-mentioned data, substitute formula (10), utilize matlab program, use Runge-Kutta numerical integration method to solve described reflector equation and obtain the discrete point data of reflector profile, obtain reflector model through rotation and three-dimensional software fitting, as shown in picture 2. At this time, the diameter of the reflector is 63.6mm.

The obtained reflector is used in the microscope illumination system, and the model diagram of the reflector and the simulation diagram of the microscope illumination system can be seen in Fig. 3 and Fig. 4 .

Turn on the LED light source, after the light is reflected by the reflector, a spot with a diameter of 90mm is formed on the target plane, and the uniformity is >85%. See Fig. 5 and Fig. 6 for the calculated results of ray tracing and illuminance distribution of the reflector designed by the present invention. Fig. 5 is the illuminance distribution diagram in the lighting area; Fig. 6 is the illuminance distribution curve in the horizontal and vertical directions; A line among the figures Represents the illuminance distribution curve in the vertical direction; line B represents the illuminance distribution curve in the horizontal direction; the illuminance uniformity of the reflector of the present invention reaches 90.6%, and the energy utilization rate reaches 99.6%.

Claims (2)

1, a kind of method for designing of the even illumination reflector of LED based on optical extend is characterized in that, comprising:

(1) be that initial point is set up polar coordinate system with the led light source,

(2) need to determine the illuminated target zone at the opposite direction place of the beam emissions of led light source;

(3) utilize following curvilinear equation to set up the reflecting surface curve at the positive direction place of the beam emissions of led light source,

$\frac{\mathrm{dr}}{\mathrm{d\&theta;}}=r\tan \left(\frac{\mathrm{\&theta;}-\arctan \frac{r\sin \mathrm{\&theta;}-\frac{\sin \mathrm{\&theta;}}{\sin {\mathrm{\&theta;}}_{\max }}R}{r\cos \mathrm{\&theta;}+x_0}}{2}\right)$

In the formula:

R is the distance between any point P on led light source light-emitting area center and the reflecting surface;

θ is that led light source light-emitting area center is transmitted into the light of any point P on the described reflecting surface and the angle of led light source light-emitting area normal;

θ _MaxThe maximum angle of divergence for led light source light-emitting area output beam;

x ₀Be the distance between illumination target plane and the led light source light-emitting area center;

R is the radius of field of illumination on the objective plane;

(4) the reflecting surface curve is obtained the reflecting surface of the described even illumination reflector of LED based on optical extend around led light source light-emitting area centre normal rotation.

2, the even illumination reflector of a kind of LED based on optical extend, comprise led light source and be used for the light of led light source emission is reflexed to the reflecting surface that needs the illuminated target plane, it is characterized in that: described reflecting surface is the curved surface that curve rotation that following curvilinear equation limited is determined:

$\frac{\mathrm{dr}}{\mathrm{d\&theta;}}=r\tan \left(\frac{\mathrm{\&theta;}-\arctan \frac{r\sin \mathrm{\&theta;}-\frac{\sin \mathrm{\&theta;}}{{\sin \mathrm{\&theta;}}_{\max }}R}{r\cos \mathrm{\&theta;}+x_0}}{2}\right)$

In the formula:

R is the distance between any point P on led light source light-emitting area center and the reflecting surface

θ is that led light source light-emitting area center is transmitted into the light of any point P on the described reflecting surface and the angle of led light source light-emitting area normal;

θ _MaxThe maximum angle of divergence for led light source light-emitting area output beam;

x ₀Be the distance between illumination target plane and the led light source light-emitting area center;

R is the radius of field of illumination on the objective plane;

Wherein said curved surface is that the curve negotiating that above-mentioned curvilinear equation is determined forms around the rotation of led light source light-emitting area centre normal.

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