CN101852385A - Light distribution lens for LED street light - Google Patents

Abstract

The invention relates to a light distribution lens for an LED street lamp, wherein an LED comprises an LED chip and a packaging lens packaged together with the LED chip and provided with an optical axis, and the lens comprises: the continuous saddle-shaped light distribution curved surface is symmetrical about the optical axis and is used for distributing Lambertian-distributed light emitted by the corresponding LED chip into a batwing-shaped light intensity distribution with a large angle along the length direction of a road; the concave hemispherical surface is positioned at the bottom of the lens, is symmetrical about the optical axis and is matched with the shape of the corresponding LED packaging lens; and the connecting plane is positioned at the bottom of the lens and is used for connecting the light distribution curved surface and the hemispherical surface. The lens can match Lambertian light emitted by the corresponding LED chip into batwing-shaped light intensity distribution with a large angle along the length direction of a road, rectangular light spots are formed in the length direction of the road, the utilization rate of light is improved, the illuminance on the road surface between the street lamps is increased, and the road surface illumination is uniform.

Description

Light distribution lens for LED street light

technical field

The invention relates to the non-imaging optical technology of LED lighting, more specifically, to a light distribution lens for LED street lamps.

Background technique

The development of LED (Light Emitting Diode, light-emitting diode) technology has opened up a new era of lighting technology revolution. Because LED has many advantages such as small size, long life, high electro-optical efficiency, environmental protection and energy saving, LED street lighting technology has developed rapidly in recent years. Since the radiation angle distribution of most LED light sources is the Lambertian distribution (Lambertian distribution) of 110 degrees to 120 degrees, if there is no light distribution, the light pattern on the ground will be a large circular spot, about 50% of the light scattered outside the road is not utilized, and it will cause glare to distant vehicles or pedestrians, which does not meet the requirements of road lighting. Good road lighting requires the light distribution of street lamps to be a rectangular spot, distributing almost all the light on the road.

In addition, on some main roads, because the street lights are installed far apart, for example, the distance between the lights is 50 meters or 60 meters, it is difficult for the existing street lights to fully illuminate the road between the two lights. Sufficient lighting requires the use of large-angle LED light distribution lenses, such as light distribution lenses with a full beam angle of 135° to 145°. In order to make the illuminance on the road directly under the LED street lamp and between the LED street lamps similar, the LED street lamp also needs to be designed with a batwing-shaped light intensity distribution in the light distribution design. The light intensity distribution in the shape of bat wings can suppress the illuminance of the road directly under the street lamps, increase the illuminance of the road between the street lamps, and make the road lighting become very uniform. This is an urgent problem to be solved in this field.

Contents of the invention

The technical problem to be solved by the present invention is to provide a light distribution lens for LED street lamps, which can increase the distance between street lamps, in view of the defects in the prior art that the light utilization rate of LED street lamps is low, and the distance between lamps and lanterns makes the road surface uneven. The illuminance on the road surface makes the road surface lighting become very uniform.

The technical solution adopted by the present invention to solve the technical problem is to construct a light distribution lens for LED street lamps, the LED includes an LED chip and a packaging lens packaged with the LED chip, and has an optical axis, Wherein, the lens includes:

A continuous saddle-shaped light distribution surface, which is symmetrical about the optical axis, is used to match the light corresponding to the Lambertian distribution emitted by the LED chip into a batwing-shaped light intensity distribution with a large angle along the length direction of the road;

a concave hemispherical surface located at the bottom of the lens, symmetrical about the optical axis and matching the shape of the corresponding LED package lens; and

A connection plane, located at the bottom of the lens, is used to connect the curved light distribution surface and the hemispherical surface.

According to the light distribution lens of the present invention, on the section of the light distribution curved surface along the road width direction and passing through the optical axis, the light emitted by the corresponding LED chip has a common focus.

According to the light distribution lens of the present invention, the common focal point is located on the optical axis, and the common focal point, the optical axis and the central point of the light-emitting surface of the LED chip are mutually conjugate points.

According to the light distribution lens of the present invention, on the section of the light distribution curved surface along the road width direction and passing through the optical axis, the angle between the edge light of the lens and the optical axis is

为32°。According to the light distribution lens of the present invention,

is 32°.

According to the light distribution lens of the present invention, on the section of the curved light distribution surface along the road length direction and passing through the optical axis, the angle between the light with the largest exit angle and the optical axis is ω, 60°<ω< 75°.

According to the light distribution lens of the present invention, ω is 70°.

According to the light distribution lens of the present invention, the section curve of the light distribution curved surface along the long direction of the road and passing through the optical axis satisfies the following conditions:

The light emitted from the center of the LED chip, when the angle is smaller than ω, the light is divergent after passing through the lens, and its exit angle δ' conforms to:

${\mathrm{<span\; class="notranslate">\; \&delta;</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; the\; tan</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; [</span>\frac{\mathrm{<span\; class="notranslate">\; \&delta;</span>}}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}\mathrm{<span\; class="notranslate">\; the\; tan</span>}\mathrm{<span\; class="notranslate">\; \&omega;</span>}<span\; class="notranslate">\; ]</span>$

When the light emitted from the center of the LED chip, when the angle is greater than ω, the light converges to the middle of the spot, and its exit angle conforms to:

${\mathrm{<span\; class="notranslate">\; \&delta;</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; the\; tan</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; [</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; \&omega;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&delta;</span>}}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}\mathrm{<span\; class="notranslate">\; the\; tan</span>}\mathrm{<span\; class="notranslate">\; \&omega;</span>}<span\; class="notranslate">\; ]</span>$

δ is the angle of light emitted from the LED chip, and δ' is the outgoing angle after being refracted by the lens.

The light distribution lens for LED street lamp implementing the present invention has the following beneficial effects: the light corresponding to the Lambertian distribution emitted by the LED chip can be matched into a batwing-shaped light intensity distribution with a large angle along the length direction of the road. Rectangular light spots are formed in the long direction, which improves the utilization rate of light, increases the illuminance on the road between street lamps, and makes the road lighting more uniform.

Description of drawings

The present invention will be further described below in conjunction with accompanying drawing and embodiment, in the accompanying drawing:

Fig. 1 is the isometric view of lens among the present invention;

Fig. 2 is a top view of the lens in the present invention; wherein the A-A section is a section along the road width direction and passing through the optical axis, and the B-B section is a section along the road length direction and passing through the optical axis.

Fig. 3 is the side view of lens among the present invention;

Fig. 4 is the front view of lens among the present invention;

Fig. 5 is the bottom view of lens among the present invention;

Fig. 6 is a sectional view along A-A in Fig. 2;

Fig. 7 shows the mathematical model of the outline of the section in Fig. 6;

Fig. 8 is a sectional view along B-B in Fig. 2;

Fig. 9 shows the mathematical model of the outline of the section in Fig. 8;

Fig. 10 shows the numerical calculation result of the cross-sectional outline coordinates of A-A, B-B in Fig. 2;

Fig. 11 shows cross-sectional curves at different angles to the Z axis through the O point;

Figure 12 shows the position of the light rays of the lens at different angle sections;

Figure 13 shows the contour lines of the lens at different angle sections;

Figure 14 shows a solid model of a lens;

Figure 15 shows the ray trace of the lens;

Figures 16a-16c show the illuminance distribution of the lens at a distance of 12 meters;

Figure 17 shows a polar plot of the far-field angular distribution of lens intensity in a batwing shape;

Figure 18 shows a Cartesian plot of the far-field angular distribution of lens intensity;

Figure 19 shows the arrangement of lenses on the PCB;

Figure 20 shows the ray tracing of the LED street lamp;

Figures 21a-21c show the illuminance distribution of LED street lights at a distance of 12 meters;

Fig. 22 shows a polar coordinate diagram of the far-field angular distribution of street light intensity in a batwing shape;

Fig. 23 shows a Cartesian plot of the far-field angular distribution of street light intensity.

Detailed ways

As shown in Figures 5 and 6, the LED street lamp of the present invention includes: a circuit board (not shown), a plurality of LEDs 4 connected to the circuit board, and a light distribution lens 5 covering a single LED 4. The LED 4 includes an LED chip 7 and a spherical packaging lens 6 packaged together with the LED chip 7.

The shape of the lens 5 is shown in FIGS. 1-6 , including an optical axis OY, which passes through the center of the light-emitting surface of the LED chip 7 and is perpendicular to the light-emitting surface of the LED chip 7 . The lens 5 has a continuous saddle-shaped light distribution curved surface 1, the light distribution curved surface 1 is symmetrical about the optical axis OY, and is not composed of two partial spherical surfaces and a transition surface between the two partial spherical surfaces. 4. The Lambertian distributed light is matched to a batwing-shaped light intensity distribution with a large angle along the road direction, forming a uniformly distributed rectangular light spot covering the road. There is a concave hemispherical surface 2 at the bottom of the lens 5, and the hemispherical surface 2 takes the center position O of the LED chip 7 as the center of the sphere, and the shape matches the shape of the spherical package lens 6 of the LED 4. The main function of the hemispherical surface 2 is to buckle the lens 5 above the LED 4, and at the same time, the hemispherical surface 2 can keep the light propagation direction from the LED 4 unchanged, and only the saddle-shaped curved surface 1 above distributes the light emitted by the LED 4 . The bottom of the lens 5 also has a connection plane 3 between the saddle-shaped curved surface 1 and the hemispherical surface 2. The connection plane 3 has no influence on the optical properties of the lens 5, and any shape can be arranged on it for installing the lens 5. Stuck feet.

为大于等于30°的一个角度，此发明优选为32°。Referring to Figure 6, on the AA cross-section obtained by the light distribution curved surface 1 along the road width direction and through the optical axis OY, the beam angle from the lens 5 needs to just cover the width of the road. Assuming that the road has three lanes, then the light spot The width needs to cover exactly the range of 3 lanes, so this direction needs to carry out converging light distribution for LED4, and the angle of light distribution needs to be determined according to the width of the road and the installation height of the lights. Generally, the full angle of the beam in this direction is designed to be 60 ° around. In Fig. 6, point O is the center position of the LED chip 7 with Lambertian distribution. In the AA cross-section, all the light emitted from the center position O of the LED chip 7 passes through the hemispherical surface 2 and the saddle-shaped curved surface 1, and then extends in the opposite direction. The lines all intersect at the focal point F, and F is located on the optical axis OY. The angle between the edge ray FBC of the lens 5 and the optical axis OY is

It is an angle greater than or equal to 30°, preferably 32° in this invention.

F点的位置由边缘光线角度和B点的位置决定：Referring to FIG. 7 , the contour line of the lens 5 along the AA cross section is calculated by the mathematical model using the integral iteration method. Suppose P(x, y) is a point on the contour line; NN is the normal line of point P; KK is the tangent line of point P; VV is the vertical line passing through point P; HH is the horizontal line passing point P; FC is the lens 5 edge rays, the angle between FC and OY axis is

The position of point F is determined by the marginal ray angle and the position of point B is determined by:

Point B is the initial point of the contour line, assuming that its corresponding coordinate value is (3.5, 0). Point P corresponds to the outgoing angle of the light emitted from the center O of the LED chip 7 is θ, and the angle between the outgoing light and the vertical line VV after refraction by the curved surface is θ′, then

$\mathrm{<span\; class="notranslate">\; the\; tan</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; x</span>}}{\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; OF</span>}}$

${\mathrm{<span\; class="notranslate">\; \&theta;</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; the\; tan</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}\frac{\mathrm{<span\; class="notranslate">\; x</span>}}{\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; OF</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

i is the angle between the incident ray OP at point P and the normal NN; o is the angle between the outgoing ray PR at point P and the normal NN; γ is the angle between the tangent KK and the horizontal line HH . According to the right angle ∠VPH, there are:

$<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&gamma;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; o</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ,</span>$

o＝γ-θ′ (3)

According to the coordinates of point P, there are:

$\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; the\; tan</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}\frac{\mathrm{<span\; class="notranslate">\; x</span>}}{\mathrm{<span\; class="notranslate">\; the\; y</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

From the triangle OFP there is:

θ=β+θ'

Then from the right angle/HPV, we have:

$<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&gamma;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&beta;</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}$

$<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&gamma;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}$

i=γ-θ (5)

According to Snell's law of refraction at point P:

nsini=sin o

nsin(γ-θ)=sin(γ-θ′)

nsinγcosθ-ncosγsinθ=sinγcosθ′-cosγsinθ′

inferred:

$\mathrm{<span\; class="notranslate">\; the\; tan</span>}\mathrm{<span\; class="notranslate">\; \&gamma;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; no</span>}\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; sin</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}^{<span\; class="notranslate">\; \&prime;</span>}}{\mathrm{<span\; class="notranslate">\; no</span>}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; cos</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}^{<span\; class="notranslate">\; \&prime;</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 6</span>}<span\; class="notranslate">\; )</span>$

In the above formula, n is the refractive index of the lens 5, which is determined by the material of the lens 5, and the material of the lens 5 is PMMA or PC. Since the differential of the position coordinates of the point P on the curve has the following relationship with the tangent angle of the tangent line KK:

$\frac{\mathrm{<span\; class="notranslate">\; dy</span>}}{\mathrm{<span\; class="notranslate">\; dx</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; the\; tan</span>}\mathrm{<span\; class="notranslate">\; \&gamma;</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 7</span>}<span\; class="notranslate">\; )</span>$

Among them, dx and dy are the finite elements of X and Y coordinates, and the coordinates of the next point of point P are:

x _next = x+dx (8)

y _next = y+dy

Assuming that the microelement dy=0.01mm, combined with formula (1) to formula (8), the coordinate point data of the contour line of the AA section can be calculated by the integral iteration method.

Referring to Fig. 8, on the cross-section B-B of the light distribution curved surface 1 along the long direction of the road and passing through the optical axis OY, the light distribution of the lens 5 along this cross-section is mainly responsible for the illumination in the long direction of the road, and the angle of the light distribution needs to be determined according to the distance between the lamps and the installation of the lamps. height to decide. For example, when the lamp distance is 32 meters and the installation height of the lamp is 10 meters, the light distribution angle (full beam angle) in the road direction is about 120°. On some main roads, because the street lights are installed far apart, such as 50 meters or 60 meters, in order to fully illuminate the area between the two lights, it is necessary to use a large-angle light distribution lens 5, for example, a beam with a full angle of 135 °～145°lens. In the present invention, the full angle of divergence of the preferred beam is 140°. In order to make the illuminance on the road directly under the LED street lamps and between the LED street lamps similar, the lens 5 needs to be designed to have a batwing-shaped light intensity distribution when designing the light distribution. The batwing-shaped light intensity distribution can suppress the illuminance of the road directly under the street lamps, increase the illuminance of the road between the street lamps, and make the road lighting more uniform.

In Figure 8, the ray with an angle of ω is the edge ray of the lens 5, that is, the light with the largest exit angle. ω determines the farthest lighting position of the street light spot along the road. The size of ω determines the allowable distance between the two lights. The lamp distance, ω is greater than 60° and less than 75°, and this invention ω is preferably 70°. The light emitted from the center O of the LED chip 7, when the angle is smaller than ω, the light is divergent after passing through the lens 5, and its exit angle δ' satisfies the following conditions:

${\mathrm{<span\; class="notranslate">\; \&delta;</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; the\; tan</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; [</span>\frac{\mathrm{<span\; class="notranslate">\; \&delta;</span>}}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}\mathrm{<span\; class="notranslate">\; the\; tan</span>}\mathrm{<span\; class="notranslate">\; \&omega;</span>}<span\; class="notranslate">\; ]</span>$

When the light emitted from the center of the LED chip, when the angle is greater than ω, the light converges to the middle of the spot, and its exit angle satisfies:

${\mathrm{<span\; class="notranslate">\; \&delta;</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; the\; tan</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; [</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; \&omega;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&delta;</span>}}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}\mathrm{<span\; class="notranslate">\; the\; tan</span>}\mathrm{<span\; class="notranslate">\; \&omega;</span>}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 10</span>}<span\; class="notranslate">\; )</span>$

In the above formula, δ is the angle of light emitted from the center O of the LED chip 7 , δ′ is the outgoing angle after being refracted by the lens 5 , and ω is the angle of the peripheral light of the lens 5 . When the outgoing light satisfies the above formulas (9) and (10), the formed light distribution is the far-field angular distribution of light intensity in the shape of a batwing. For detailed simulation results, refer to the subsequent content.

The contour line of the B-B section is calculated by the mathematical model in Fig. 9 by the integral iteration method. As shown in Figure 9, O in the figure is the center position of the LED chip, Q(x, y) is a point on the cross-sectional contour line, the incident light corresponding to this point is OQ, and the angle between OQ and the optical axis OS is δ; QR is the outgoing light, and the angle between it and the vertical line VV is δ′; NN is the normal line of point Q; KK is the tangent line of point Q, and the angle between it and the horizontal line HH is γ; i is the incident light OQ and the normal line NN The included angle; o is the included angle between the outgoing light QR and the normal NN. The relationship between δ′ and δ angle is as follows:

${\mathrm{\&delta;}}^{\&prime;}={\mathrm{the\; tan}}^{-1}\left[\frac{\mathrm{\&delta;}}{\mathrm{\&omega;}}\mathrm{the\; tan}\mathrm{\&omega;}\right],$ When δ≤ω

${\mathrm{\&delta;}}^{\&prime;}={\mathrm{the\; tan}}^{-1}\left[\frac{2\&times;\mathrm{\&omega;}-\mathrm{\&delta;}}{\mathrm{\&omega;}}\mathrm{the\; tan}\mathrm{\&omega;}\right],$ When ω＜δ≤90° (11)

From the right angle ∠KQN, we have:

$\mathrm{<span\; class="notranslate">\; o</span>}<span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&delta;</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&gamma;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}$

o＝δ′-γ (12)

From the other side of the right angle ∠KQN, there are:

$\mathrm{<span\; class="notranslate">\; \&gamma;</span>}<span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&delta;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}$

i=δ-γ (13)

According to Snell's law of refraction at point Q:

n sini = sin o

n sin(δ-γ)=sin o

n sinδcosγ-n cosδsinγ=sinδ′cosγ-cosδ′sinγ

$\mathrm{<span\; class="notranslate">\; the\; tan</span>}\mathrm{<span\; class="notranslate">\; \&gamma;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; no</span>}\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&delta;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; sin</span>}{\mathrm{<span\; class="notranslate">\; \&delta;</span>}}^{<span\; class="notranslate">\; \&prime;</span>}}{\mathrm{<span\; class="notranslate">\; no</span>}\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&delta;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; cos</span>}{\mathrm{<span\; class="notranslate">\; \&delta;</span>}}^{<span\; class="notranslate">\; \&prime;</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 14</span>}<span\; class="notranslate">\; )</span>$

In the above formula, n is the refractive index of the lens 5, because the differential of the position coordinates of the point Q of the curve has the following relationship with the tangent angle of the tangent line KK:

$\mathrm{<span\; class="notranslate">\; the\; tan</span>}\mathrm{<span\; class="notranslate">\; \&gamma;</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; dy</span>}}{\mathrm{<span\; class="notranslate">\; dx</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 15</span>}<span\; class="notranslate">\; )</span>$

y _next = y+dy (16)

x _next = x+dx

Taking the coordinates of point S calculated by the mathematical model of the A-A section contour line as the starting point, combined with formulas (11) to (16), the numerical coordinates of the B-B section contour line can also be calculated by the integral iteration method.

According to the mathematical models in Fig. 7 and Fig. 9, the numerical calculation results of the coordinates of the A-A section and the B-B section contour line shown in Fig. 10 are obtained.

Referring to Figure 11, after the A-A section and B-B section outlines are calculated, the angles between the point O and the Z axis are: δ=15°, 30°, 45°, 60°, 75°, 90° of each section Contour line coordinate values can also be calculated sequentially.

，可以根据图12的几何关系算出。图中O为透镜5所在位置，ABCD为LED发出的光经过透镜5之后在距离为h的位置所形成的照射范围，形状为长方形，光线OL为截面OLL′内的边缘光线，∠LOH＝ω，这里优选为70°。中间的三角形ΔOWW′为δ＝0时候的光束截面，其边缘光线OW的角度为

往左的各个截面依次为δ＝15°、30°、45°、90°、60°、75°、70°的光束截面，其边缘光线的角度分别为：

22.05°、17.1°、15.9°、13.7°、12.07°、12.06°，δ＝75°和90°时的光束截面在δ＝70°之内，是因为δ＝70°是边缘光线，当δ超过了边缘光线之后，其光线的出射角将向光斑中间会聚，见公式(11)。According to Figure 9 and formula (11), when the angle ω=70° of the marginal ray, when the incident angle δ in the BB section is 15°, 30°, 45°, 60°, 75°, 90°, the exit angles are respectively It is: δ'=30.5°, 49.6°, 60.5°, 67°, 68.6°, 62.9°. The angle of the marginal rays passing through each section of O

, can be calculated according to the geometric relationship in Figure 12. In the figure, O is the position of the lens 5, and ABCD is the irradiation range formed by the light emitted by the LED at a distance h after passing through the lens 5. , which is preferably 70° here. The middle triangle ΔOWW' is the beam section when δ=0, and the angle of the edge ray OW is

Each section to the left is the beam section of δ=15°, 30°, 45°, 90°, 60°, 75°, and 70°, and the angles of the edge rays are:

22.05°, 17.1°, 15.9°, 13.7°, 12.07°, 12.06°, the beam cross sections at δ=75° and 90° are within δ=70°, because δ=70° is a marginal ray, when δ exceeds After the edge rays are detected, the exit angle of the rays will converge toward the center of the spot, see formula (11).

用同样的方法根据公式(1)至公式(8)可以算出图11中这些截面轮廓线的坐标数值。将这些截面的轮廓线放在同一个二维的直角坐标轴上，轮廓线的相对位置和形状如图13所示。The angles of the edge beams of different sections calculated according to the above

In the same way, the coordinate values of these section contour lines in Fig. 11 can be calculated according to formula (1) to formula (8). Put the contour lines of these sections on the same two-dimensional rectangular coordinate axis, and the relative position and shape of the contour lines are shown in Figure 13.

Import the coordinates of different cross-section contour lines calculated above into the 3D modeling software, use these contour lines as the skeleton, and envelop a layer of curved surface to form a lens entity. At the same time, a solid model of the LED is established according to the geometric dimensions of the high-power Lambertian LED. The saddle-shaped lens 5 and the solid model of the LED are shown in FIG. 14 .

Input the physical model of lens 5 and LED into ray tracing software such as LightTools, assign the light-emitting surface of the LED chip to the characteristics of the light source, and place a receiving screen 12 meters away, then ray tracing and photometric analysis can be performed on lens 5 , the ray tracing of a single lens 5 is shown in FIG. 15 .

The illuminance distribution of the lens 5 at 12 meters is shown in Figure 16a-16c. The shape of the light spot is rectangular, the length and width of the light spot are about 70 meters x 16 meters, the length direction is the direction of the road, the width direction is the direction perpendicular to the road, and the peak illuminance Half of the position is about ±32 meters. The far-field angular distribution of the light intensity of lens 5 is shown in Figure 17 and Figure 18. In the direction of the road, the far-field angular distribution curve of the light intensity is in the shape of a batwing, and the angular width at half of the peak light intensity is about ±70°. In the direction of the road, the angular width at half of the peak light intensity is about ±32°.

An arrangement of LED 4 on the PCB is shown in Figure 19. The B-B direction of all lenses 5 is along the direction of the road, and the A-A direction is perpendicular to the direction of the road. As long as the directions of the lenses 5 are consistent, the arrangement of the lenses 5 There can be many ways, and they can be arranged in rectangles, circles, ellipses, stars and any other shapes, here they are arranged in ellipses. In addition, as long as the average illuminance of the road surface is above 20lux, the number of arrangements can be increased or decreased arbitrarily according to the output luminous flux of the LEDs and the installation height of the street lamps. The ray tracing of the overall LED street light is shown in Figure 20, and the receiving screen is placed 12 meters away for photometric analysis after ray tracing.

The illuminance distribution on the screen is shown in Figures 21a-21c. The lens 5 forms a uniformly distributed rectangular light spot with a length and width of about 70 meters x 16 meters. The length direction is the direction of the road, and the width direction is the direction perpendicular to the road. Half of the peak illuminance The location is about ±32 meters. The far-field angular distribution of the light intensity of lens 5 is shown in Figure 11 and Figure 23. In the direction of the road, the far-field angular distribution curve of the light intensity is in the shape of a batwing, and the angular width at half of the peak light intensity is about ±70°. In the direction of the road, the angular width at half of the peak light intensity is about ±32°.

The light distribution lens 5 of the present invention can form the light intensity distribution of the Lambertian distribution corresponding to the LED chip 7 into a batwing shape with a large angle along the length direction of the road, and form a rectangular spot on the long direction of the road, which improves the The utilization of light increases the illuminance on the road between street lamps, making the road lighting uniform.

Claims (8)

1. light-distribution lens that is used for the LED street lamp, described LED comprises led chip and the package lens that is packaged together with described led chip, and has optical axis, it is characterized in that, described lens comprise:

Continuous heterocoelous light distribution curved surface, about described symmetrical, the light that is used for lambertian distribution that corresponding led chip is sent is made into along the light distribution of the batswing tab shape of link length direction wide-angle;

The hemisphere face of depression is positioned at the bottom of described lens, is complementary about described symmetrical and with the shape of corresponding LED package lens; And

Connect the plane, be positioned at the bottom of described lens, be used to connect described light distribution curved surface and described hemisphere face.

2. light-distribution lens according to claim 1 is characterized in that, described light distribution curved surface is along the road cross direction and by on the cross section of described optical axis, the light that corresponding led chip sends has common focus after described hemisphere face and light distribution curved surface outgoing.

3. light-distribution lens according to claim 2 is characterized in that, described common focus is positioned on the described optical axis, and the central point of the light-emitting area of described common focus, described optical axis and led chip conjugate point each other.

4. light-distribution lens according to claim 3 is characterized in that, described light distribution curved surface is along the road cross direction and by on the cross section of described optical axis, the rim ray of lens and the angle of described optical axis are

5. light-distribution lens according to claim 4 is characterized in that, It is 32 °.

6. light-distribution lens according to claim 1 and 2 is characterized in that, described light distribution curved surface is along the road length direction and by on the cross section of described optical axis, the light of angle of emergence maximum and the angle of described optical axis are ω, 60 °＜ω＜75 °.

7. light-distribution lens according to claim 6 is characterized in that, ω is 70 °.

8. light-distribution lens according to claim 6 is characterized in that, described light distribution curved surface meets the following conditions along road length direction and the cross section curve by described optical axis:

The light that sends from the led chip center, when angle during less than ω, behind lens, light is dispersed, and its angle of emergence δ ' meets:

${\mathrm{\&delta;}}^{\&prime;}={\tan }^{-1}\left[\frac{\mathrm{\&delta;}}{\mathrm{\&omega;}}\tan \mathrm{\&omega;}\right]$

When the light that sends from the led chip center, when angle during greater than ω, light is assembled in the middle of hot spot, and its angle of emergence meets:

${\mathrm{\&delta;}}^{\&prime;}={\tan }^{-1}\left[\frac{2\&times;\mathrm{\&omega;}-\mathrm{\&delta;}}{\mathrm{\&omega;}}\tan \mathrm{\&omega;}\right]$

δ is the angle of the light that sends from led chip, and δ ' is for through the shooting angle after the lens refraction.

Images