CN104279509A - LED (Light-emitting Diode) uniform light intensity lens - Google Patents

Abstract

The invention discloses an LED (Light-emitting Diode) uniform light intensity lens. The lens is in a central axle symmetry shape, and the emergent surface of the lens is a free-form surface. A cross section passing a central axle of the lens is adopted as a reference plane, a coordinate system is built, the central axle is adopted as Z-axle, an original point is on the central axle, an LED chip is placed on the original point, the direction passing the original point and being vertical to the central axle is adopted as X-axle, an energy corresponding relation of the chip and a target surface is built through setting the virtual target surface, a lens free-form surface forming curve is obtained, and the forming curve is rotated by a circle around the Z-axle to obtain a free-form surface shape of the emergent surface of the LED uniform light intensity lens. The LED uniform light intensity lens is relatively intuitive, simple and convenient to calculate, larger in design target angle selection range, and better in light intensity uniformity, and has favorable application prospect in the fields of beacon lights, traffic lights and other signal indicators or indoor illumination and the like which require uniform light intensity distribution.

Description

The even power lenses of a kind of LED

Technical field

The present invention relates to technical field of LED illumination, particularly the even power lenses of a kind of LED.

Background technology

LED, because of advantages such as its light efficiency are high, energy consumption is low, the life-span is long, the response time is short and pollution-free, just progressively replaces conventional light source, becomes the competitive novel solid light source of 21 century most.LED chip light distribution becomes nearly lambert's type, is different from conventional light source, need carry out luminous intensity distribution design for it.Freeform optics relies on that it can realize the redistributing of luminous energy, optical system volume is little, efficiency is high and the advantage such as light type is controlled, be widely used in, in the face type design of spot light and expansion light source uniform illumination light distribution device, becoming the effective means that LED optical system realizes uniform illumination luminous intensity distribution.

Need to realize even light distribution in the signal lamp such as navigation light, traffic lights or room lighting, freeform optics is applied less in this.Have researcher to use the conservation of energy to set up partial differential equation, realize the design of spot light even power lenses, or by edge-light collimation method principle, realize the even power lenses of expansion light source and design, two kinds of calculating are loaded down with trivial details, not easily promote.

Summary of the invention

Technical problem to be solved by this invention is for above-mentioned the deficiencies in the prior art, provides even power lenses of a kind of LED and preparation method thereof, and this method for designing relative straightforward, calculates easy, and design object angle Selection leeway is comparatively large, and uniform intensity degree is better.

Technical scheme of the present invention is as follows:

The even power lenses of a kind of LED, axisymmetric shape centered by the even power lenses of LED, lens exit facet is free form surface.

The light that LED chip sends, through the refraction of the even power lenses exit facet of LED, realizes isocandela outgoing.

The another preparation method being to provide the even power lenses of a kind of LED with object of the present invention, the even power lenses exit facet of LED is free form surface; Lens exit facet free form surface is determined by the following method:

To cross the cross section of the even power lenses central shaft of LED for datum level, set up coordinate system, central shaft is Z axis, initial point on center shaft, LED chip is placed on initial point, crosses initial point and be X-axis with the direction of central axis, sets up the energy corresponding relation of chip and target face, lens free form surface forming curve, forming curve to be rotated a circle to obtain LED even power lenses exit facet free form surface shape around Z axis.

Described target face is hemispherical virtual target face.

The forming curve of described lens exit facet free form surface is determined as follows:

LED chip light distribution is I _θ=I _ocos θ, wherein I ₀centered by light intensity, θ is the angle of LED emergent ray and central shaft;

1) even light intensity is obtained by the conservation of energy:

The light of θ=0 is propagated along Z axis, and after lens luminous intensity distribution, the line of the intersection point of maximum angle of emergence light on virtual target face and the origin of coordinates with the angle of Z axis is the light refraction of θ=pi/2 arrives with the point of intersection in virtual target face, obtain even light intensity according to the conservation of energy:

2) angle of line with Z axis of intersection point on virtual target face of incident ray and Z axis angle theta and emergent ray and the origin of coordinates is obtained by energy corresponding relation corresponding relation:

3) recursion tries to achieve point coordinates on forming curve:

Will be divided into M decile, sleeping article i-th, emergent ray O _iintersection point on virtual target face and the line of the origin of coordinates with the angle of Z axis are:

Corresponding i-th incident ray i is tried to achieve by formula (2) _iwith the angle of optical axis Z axis be:

If A _ipoint coordinates is (x _i, z _i), B again _ipoint coordinates is then incident ray i _iunit vector be:

${\stackrel{\→}{\mathrm{in}}}_i=\frac{1}{\sqrt{{x_i}^2+{z_i}^2}}(x_i,z_i)---\left(3\right)$

Emergent ray O _iunit vector be:

A can be obtained again according to snell law _ithe normal vector of point:

${\stackrel{\→}{N}}_i(N_{i\_x},N_{i\_z})=n\·{\stackrel{\→}{\mathrm{in}}}_i-{\stackrel{\→}{\mathrm{out}}}_i---\left(5\right)$

N is the refractive index of lens, then A _ithe tangential equation of point is:

$\frac{1}{-\frac{N_{i\_z}}{N_{i\_x}}}=\frac{z-z_i}{x-x_i}---\left(6\right)$

θ again _i+1corresponding incident ray i _i+1linear equation be:

z＝cot(θ _i+1)x (7)

Simultaneous formula (6), formula (7) can cross A _ithe tangent line of point and θ _i+1corresponding incident ray i _i+1intersection point, be approximately A _i+1;

θ ₀corresponding original light i ₀for the light along Z axis forward-propagating, its propagation path is selected initial point A ₀(0, d) as the starting point of lens optical surfaces, then recursion can obtain M discrete point A successively according to above-mentioned steps _i, i ∈ [1, M], connects M discrete point and obtains forming curve.

The present invention has the following advantages and effect relative to prior art tool: provide even power lenses of a kind of LED and preparation method thereof, by adopting hemispherical virtual target face, set up the integral relation of Flux conservation, recursion tries to achieve discrete data point on lens Free-Form Surface Profile curve, generates lens body model.This method for designing relative straightforward, calculates easy, and design object angle Selection leeway is comparatively large, and uniform intensity degree is better, needs to realize even light distribution field have a good application prospect at the signal lamp such as navigation light, traffic lights or room lighting etc.

Accompanying drawing explanation

Fig. 1 is the front view of even power lenses in embodiment;

Fig. 2 is the stereogram of evenly power lenses shown in Fig. 1;

The coordinate system schematic diagram of even power lenses free form surface is solved in Fig. 3 embodiment of the present invention;

Fig. 4 is the surface of intensity distribution in embodiment;

Detailed description of the invention

Below in conjunction with accompanying drawing, enforcement of the present invention is described in further detail.

As depicted in figs. 1 and 2, the even power lenses exit facet 101 of LED of the present invention is free form surface.As shown in Figure 3, the light that LED chip 201 sends, through the refraction of the even power lenses exit facet 101 of LED, realizes isocandela outgoing.Lens exit facet 101 free form surface is determined by the following method:

Lens thickness d=5mm, lens material is a lens common used material PC, refractive index n=1.591.

Forming curve, determine as follows:

Make lens shooting angle the angle of line with Z axis of intersection point on virtual target face of incident ray and Z axis angle theta and emergent ray and the origin of coordinates is obtained by energy corresponding relation corresponding relation:

Recursion tries to achieve point coordinates on forming curve:

Will be divided into 500 deciles, namely article i-th, emergent ray O _ithe line of 203 intersection points on virtual target face and the origin of coordinates with the angle of Z axis is:

Try to achieve corresponding i-th condition by formula (2) and penetrate light i _i202 with the angle of optical axis Z axis are:

If A _ipoint coordinates is (x _i, z _i), B again _ipoint coordinates is then incident ray i _ithe unit vector of 202 is:

${\stackrel{\→}{\mathrm{in}}}_i=\frac{1}{\sqrt{{x_i}^2+{z_i}^2}}(x_i,z_i)---\left(3\right)$

Emergent ray O _ithe unit vector of 203 is:

A can be obtained again according to snell law _ithe normal vector of point:

${\stackrel{\→}{N}}_i(N_{i\_x},N_{i\_z})=n\·{\stackrel{\→}{\mathrm{in}}}_i-{\stackrel{\→}{\mathrm{out}}}_i---\left(5\right)$

N is the refractive index of lens, then A _itangent line 204 equation of point is:

$\frac{1}{-\frac{N_{i\_z}}{N_{i\_x}}}=\frac{z-z_i}{x-x_i}---\left(6\right)$

θ again _i+1corresponding incident ray i _i+1the linear equation of 205 is:

z＝cot(θ _i+1)x (7)

Simultaneous formula (6), formula (7) can cross A _ithe tangent line 204 of point and θ _i+1corresponding incident ray i _i+1the intersection point of 205, is approximately A _i+1;

θ ₀corresponding original light i ₀for the light along Z axis forward-propagating, its propagation path is selected initial point A ₀(0,5) as the starting point of lens optical surfaces, then recursion can obtain 1500 discrete point A according to above-mentioned steps successively _i, i ∈ [1,1500], then discrete point coordinate is imported in three-dimensional graphics software Solidworks, selected rotating shaft, then pivots curve one week, obtains the rear surface free form surface of lens.

Fig. 1, Fig. 2, be respectively front view and the stereogram of the even power lenses obtained by such scheme.

Fig. 4 is the even power lenses surface of intensity distribution of this LED, can find out that design lens ensemble uniform intensity degree is higher.

Claims (4)

1. the even power lenses of LED, axisymmetric shape centered by the even power lenses of described LED, is characterized in that lens exit facet (101) is free form surface.

2. a preparation method for the even power lenses of LED, the even power lenses exit facet (101) of described LED is free form surface; It is characterized in that described lens exit facet (101) free form surface is determined by the following method: to cross the cross section of the even power lenses central shaft of LED for datum level, set up coordinate system, central shaft is Z axis, initial point on center shaft, LED chip (201) is placed on initial point, cross initial point and be X-axis with the direction of central axis, set up the energy corresponding relation of chip and target face, lens free form surface forming curve, forming curve to be rotated a circle to obtain LED even power lenses exit facet (101) free form surface shape around Z axis.

3. the even power lenses of LED according to claim 2, is characterized in that described target face (206) is for hemispherical virtual target face.

4. the even power lenses of LED according to claim 2, is characterized in that the forming curve of described lens exit facet (101) free form surface is determined as follows:

LED chip (201) light distribution is I _θ=I ₀cos θ, wherein I ₀centered by light intensity, θ is the angle of LED emergent ray and central shaft;

1) even light intensity is obtained by the conservation of energy:

The light of θ=0 is propagated along Z axis, and after lens luminous intensity distribution, the line of the intersection point of maximum angle of emergence light on virtual target face and the origin of coordinates with the angle of Z axis is the light refraction of θ=pi/2 arrives with the point of intersection in virtual target face, obtain even light intensity according to the conservation of energy:

2) angle of line with Z axis of intersection point on virtual target face of incident ray and Z axis angle theta and emergent ray and the origin of coordinates is obtained by energy corresponding relation corresponding relation:

3) recursion tries to achieve point coordinates on forming curve:

Will be divided into M decile, namely article i-th, emergent ray O _i(203) intersection point on virtual target face and the line of the origin of coordinates with the angle of Z axis are:

Corresponding i-th incident ray i is tried to achieve by formula (2) _i(202) with the angle of optical axis Z axis be:

If A _ipoint coordinates is (x _i, z _i), B again _ipoint coordinates is then incident ray i _i(202) unit vector is:

${\stackrel{\→}{\mathrm{in}}}_i=\frac{1}{\sqrt{{x_i}^2+{z_i}^2}}(x_i,z_i)---\left(3\right)$

Emergent ray O _i(203) unit vector is:

A can be obtained again according to snell law _ithe normal vector of point:

${\stackrel{\→}{N}}_i(N_{i\_x},N_{i\_z})=n\·{\stackrel{\→}{\mathrm{in}}}_i-{\stackrel{\→}{\mathrm{out}}}_i---\left(5\right)$

N is the refractive index of lens, then A _itangent line (204) equation of point is:

$\frac{1}{-\frac{N_{i\_z}}{N_{i\_x}}}=\frac{z-z_i}{x-x_i}---\left(6\right)$

θ again _i+1corresponding incident ray i _i+1(205) linear equation is:

z＝cot(θ _i+1)x (7)

Simultaneous formula (6), formula (7) can cross A _ithe tangent line (204) of point and θ _i+1corresponding incident ray i _i+1(205) intersection point, is approximately A _i+1;

θ ₀corresponding original light i ₀for the light along z-axis forward-propagating, its propagation path is selected initial point A ₀(0, d) as the starting point of lens optical surfaces, then recursion can obtain M discrete point A successively according to above-mentioned steps _i, i ∈ [1, M], connects M discrete point and obtains forming curve.