The Fresnel Lenses that is used for high-power LED light source
Technical field
The present invention relates to a kind of Fresnel Lenses, relate in particular to a kind of Fresnel Lenses for high-power LED light source or array of source, belong to the video display field of illuminating lamps.
Background technology
Fresnel Lenses also claims Fresnel lens, is characterized in lens surface simultaneously for the light face, the another side imprinting ascending concentric circles (being the ring grain Fresnel surface).Fresnel Lenses is used widely in fields such as Projection Display, optically focused cumulative, light opticses.For example traditional high-power light-projecting lamp generally is comprised of HID light source (high-density air body discharging lamp) and Fresnel Lenses with large-size.Since the HID light source be 360 ° luminous, wherein only have a fraction of light to realize assembling by the Fresnel Lenses by the place ahead, the utilization rate of luminous energy is lower.Therefore, in order to increase the utilization rate of luminous energy, need to place in the back of HID light source the speculum of a sphere.Yet the temperature of HID light source is very high, evaporates after pitch-dark roastingization with the structural member surface easily, and the chemical substance after the evaporation can stain speculum and Fresnel Lenses, thereby reduces the reflectivity of speculum and the transmitance of Fresnel Lenses.Therefore, the light decay of traditional high-power light-projecting lamp is very serious, and the life-span is also shorter.
At present, because the technology of power type LED light source comparative maturity, and had widely in a lot of fields and to use, increasing high-power light-projecting lamp begins to use instead the array of source that the integrated high-power LED light source of multi-chip or plurality of LEDs form.Only 180 ° scope is interior luminous forwardly for this type of light source, the far field angle distribution (being distribution curve flux) of its light intensity is Lang Baixing, the light beam full-shape width of half position of peak light intensity is approximately 120 °, therefore the reflector of a sphere need to be behind light source, do not placed again, and only just most light can be collected with a Fresnel Lenses.
In the prior art, the structure of Fresnel Lenses that is used for light fixture is all more similar, includes the plane of incidence and the refractive, concave surface relative with the plane of incidence.Wherein, the plane of incidence is smooth face, and refractive, concave surface is the ring grain Fresnel surface that the ring groove by a plurality of concentric settings is split to form, and this ring grain Fresnel surface has the effect of convergence to incident ray.For example publication number is disclosed Fresnel Lenses in the Chinese patent application of CN102537832A, namely is one of them example.Because the array of source that Fresnel Lenses forms the integrated high-power LED light source of multi-chip or plurality of LEDs only has the effect of convergence of rays, when this Fresnel Lenses is used for high power LED projector, and when light source is positioned at the focal plane position of Fresnel Lenses, Fresnel Lenses can project a LEDs chip of proper alignment or the picture of a LEDs, rather than circular uniform light spots.Although can improve the shape of hot spot by out of focus, beam angle will become larger after the out of focus, and because the existence of aberration, yellow circle also can appear in the hot spot edge sometimes.Therefore, the structural limitations of Fresnel Lenses its application in the high-power LED lamp field.
Summary of the invention
Technical problem to be solved by this invention is to provide a kind of improved Fresnel Lenses.This Fresnel Lenses is particluarly suitable for using in high-power LED light source or the array of source.
In order to reach above-mentioned goal of the invention, the present invention adopts following technical scheme:
A kind of Fresnel Lenses comprises the ring grain Fresnel surface, and the back side of described ring grain Fresnel surface is basal plane, and wherein, described basal plane is to arrange the fly_eye lens array face that forms by a plurality of fly lenses unit.
More preferably, described fly lens unit is distributed on the described basal plane centered by the optical axis of described basal plane ringwise.
More preferably, each described fly lens unit has identical mixed light angle.
More preferably, described mixed light angle is between 2 °~5 °.
More preferably, described basal plane is any one in plane, arc surface, the aspheric surface.
More preferably, described basal plane is the arc surface of indent.
More preferably, described fly_eye lens array face and described basal plane are one-body molded.
Fresnel Lenses array of source provided by the invention is by the combination of ring grain Fresnel surface and fly_eye lens array face, the optically focused effect of Fresnel Lenses and the mixed light effect of fly_eye lens array face can be combined, in the situation of the beam angle that changes hardly Fresnel Lenses, output beam is carried out the mixed light of small angle range, thereby the outgoing hot spot is modified to circular uniform light spots.When light source transferred near the lens lower surface from the focal plane position of lens always, the beam angle of output beam changed to greatly from little continuously, and output facula can change to floodlight continuously from optically focused, kept changing more uniformly, without significantly bright ring and blackening always.
Description of drawings
Fig. 1 is the top view of Fresnel Lenses provided by the invention;
Fig. 2 is the upward view of Fresnel Lenses provided by the invention;
Fig. 3 is the front view of Fresnel Lenses provided by the invention;
Fig. 4 is the profile of structure shown in Figure 3;
Fig. 5 is the partial enlarged drawing of A section among Fig. 4;
Fig. 6 is the mixed light schematic diagram of Fresnel Lenses provided by the invention.
The specific embodiment
Below in conjunction with the drawings and specific embodiments particular content of the present invention is described in further detail.
In conjunction with Fig. 1 to Fig. 4 as can be known, Fresnel Lenses provided by the invention comprises circular ring grain Fresnel surface 1 and basal plane 2, and the back side of ring grain Fresnel surface 1 is basal plane 2.Wherein, basal plane 2 is the fly_eye lens array faces 3 that formed by a plurality of fly lenses unit dense arrangement.Because on basal plane 2, a plurality of fly lenses unit is similar to fly's eye with the form dense arrangement of array, so be referred to as fly_eye lens array face 3.In one embodiment of the invention, a plurality of fly lenses unit is on basal plane 2, centered by optical axis, circular array becomes array.In this Fresnel Lenses, basal plane 2 is plane of light incidence, and ring grain Fresnel surface 1 is the light outgoing plane.The light that the light source center of the led light source array 5 that forms from plurality of LEDs sends after basal plane 2 refractions, incides on the ring grain Fresnel surface 1.Wherein, 3 pairs of light of fly_eye lens array face play the low-angle mixed light, and 1 pair of light of ring grain Fresnel surface plays refraction and assembles.
The shape of basal plane 2 can be any one in plane, arc surface, the aspheric surface.This fly_eye lens array face 3 is one-body molded with basal plane 2.In one embodiment of the invention, basal plane 2 is arc surfaces (referring to profile shown in Figure 4 and A section enlarged drawing shown in Figure 5) of indent, and ring grain Fresnel surface 1 is outwardly arc surface.Wherein, basal plane 2 is planes of incidence.Compare with planar structure, the arc surface of indent has larger numerical aperture angle, can collect more light energy.
Be used for the light of incident is reflected in a plurality of fly lenses unit that this fly_eye lens array face 3 is arranged, reach the purpose of low-angle mixed light.All fly lens unit in this fly_eye lens array face 3 have identical mixed light angle, and this mixed light angle is determined by the numerical value at the numerical aperture angle of fly lens unit.In this Fresnel Lenses, mixed light angle delta θ is to be advisable between 2 °~5 °.Preferably, can adopt 3 ° as the mixed light angle of fly_eye lens array.
Such as Fig. 4 and shown in Figure 6, led light source array 5 is installed on the focal plane of this Fresnel Lenses, the light that sends from the light source center of this led light source array 5, after basal plane 2 refractions through indent circular arc, incide on the ring grain Fresnel surface 1 of upper surface, wherein, the light of 3 pairs of led light source arrays of fly_eye lens array face, 5 emissions has the effect of low-angle mixed light.Below, describe as an example of the mixed light principle of single fly lens unit shown in Figure 6 example.
The light OP that sends from the light source center O point of led light source array 5, incide on the center point P of a fly lens unit, its refracted ray PQ incides on the inclined-plane of ring grain Fresnel surface 1, after the inclined-plane refraction through ring grain Fresnel surface 1, its emergent ray QR penetrates along the direction collimation parallel with optical axis OZ.Send, incide light OP1 and the OP2 of this fly lens cell edges from the light source center O point of led light source array 5, after light P1Q1 after reflecting and P2Q2 pass through the inclined-plane refraction of ring grain Fresnel surface 1 again, its emergent ray Q1R1 and Q2R2 are crossed to first a bit, then become with emergent ray QR ± Δ θ angle is penetrated.Wherein ± Δ θ equals the mixed light angle of fly lens unit.All fly lens unit have identical mixed light angle, can guarantee that like this outgoing beam obtains more uniform mixed light.The size of this fly lens unit can be determined according to processing conditions.The radius of curvature of fly lens unit can be determined according to the numerical aperture of fly lens unit.The numerical aperture of each fly lens unit satisfies: N.A.=nsin (Δ θ), and in the formula, N.A. is the numerical aperture of fly lens unit, and n is medium refraction index, and for air, its numerical value is 1, and Δ θ is the mixed light angle.According to the diameter of this formula and fly lens unit, can calculate the radius of curvature of each fly lens unit.
In summary, Fresnel Lenses provided by the invention, combination by ring grain Fresnel surface and fly_eye lens array face, the optically focused effect of Fresnel Lenses and the mixed light effect of fly_eye lens array can be combined, in the situation of the beam angle that changes hardly Fresnel Lenses, output beam is carried out the mixed light of small angle range, eliminate the picture of a LEDs of proper alignment in the projected spot, and the outgoing hot spot is modified to circular uniform light spots, be applicable to the array of source that plurality of LEDs forms.Simultaneously, this Fresnel Lenses also is applicable to by the integrated high-power LED light source of multi-chip, wherein, fly_eye lens array has identical low-angle mixed light effect in the face of this high-power LED light source, can eliminate the picture of a LEDs chip of proper alignment in the outgoing hot spot, and its outgoing hot spot is modified to circular uniform light spots.
If use traditional Fresnel Lenses, when light source is positioned at focal plane position, the shadow that has led chip or LED in the hot spot of projection, although can improve the shape of hot spot by out of focus, but beam angle will become larger after the out of focus, and because the existence of aberration, yellow circle also can appear in the hot spot edge sometimes.And use Fresnel Lenses provided by the present invention, when Fresnel Lenses moves with respect to high-power LED light source, can effectively eliminate ring-type aperture and because the Huang circle at the hot spot edge that aberration causes.When the led light source array transfers near the lens lower surface from the focal plane position of lens always, can realize beam angle from small to large, the continuous variation of hot spot from optically focused to the floodlight, and keep changing more uniformly, without significantly bright ring and blackening always.
The above has been described in detail Fresnel Lenses provided by the present invention.For one of ordinary skill in the art, any apparent change of under the prerequisite that does not deviate from connotation of the present invention it being done all will consist of infringement of patent right of the present invention, will bear corresponding legal liabilities.