CN104566217B - Double optical lens with free curved surface for ultra-thin direct-light type LED backlight system - Google Patents
Double optical lens with free curved surface for ultra-thin direct-light type LED backlight system Download PDFInfo
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
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Abstract
The present invention is provided to double optical lens with free curved surface of ultra-thin direct-light type LED backlight system.It includes two free form surfaces, respectively constitutes the plane of incidence and exit facet；The shape of free-form surface lens is defined below：Using LED light source as originOEstablish rectangular coordinate system in space, using plane where LED bottom surfaces asPlane, excessively origin are simultaneously vertical with planeAxle beAxle, light source solid angle is divided first, and the illumination region on target illumination face is carried out annulus division, then law of conservation of energy is used, the mapping for establishing ring belt area on light source solid angle and target illumination face is closed, then catadioptric law is used, double free-form surface lens to the end are obtained by geometrical relationship.Compact of the present invention, after the light being emitted from LED is by double free-form surface lens, the uniform circular light spot of Illumination Distribution can be formed on target illumination face, and the delivery efficiency of lens is very high.
Description
Technical Field
The invention relates to the field of LED display, in particular to a double-free-form-surface optical lens for an ultrathin direct type LED backlight system.
Background
In recent years, with the rapid development of liquid crystal display technology, backlight technology, which is one of the core technologies of LCD display, has been greatly developed. As a new light source, the LED gradually replaces the traditional light source to become the main light source of the backlight system by virtue of the advantages of quick response, small volume, long service life, excellent color temperature, strong shock resistance, energy conservation, environmental protection and the like.
LED backlight systems can be classified into edge type and direct type according to the position of the LED light source. The side-light type backlight system places the LED light source at the side of the specially designed light guide plate, and generally, the number of the LEDs is small. Because the LED light source is arranged on the side surface of the backlight system, the backlight system has the advantages of lightness, thinness, simple structure and the like, but the energy utilization rate of the light source is smaller and the utilization rate is smaller when the system is thinner due to the limitation of the number of the LEDs and the brightness. In addition, the edge-lit backlight system relies on the light guide plate to distribute light, which makes it difficult to achieve area control and energy saving of the system, and cannot improve the dynamic contrast value and the dynamic image quality of the system. This design is mainly applied to medium and small size backlight systems, and if it is applied to large size backlight systems, the weight and cost of the light guide plate will increase with the increase of the system size, and the disadvantages of low light emitting brightness and poor uniformity will be more obvious.
The direct type LED backlight system does not need a light guide plate and has simple process. The direct type is mainly adopted in the large-size backlight system. In the system, the LED array is positioned at the bottom of the module, and light emitted from the LEDs passes through the light distribution unit at the bottom of the module and is diffused by the diffusion plate on the surface and then is uniformly emitted. The thickness of the direct type backlight system is determined by the distance between the bottom module and the diffuser plate, and generally, the larger the thickness of the system is, the better the uniformity is. Currently, LED light sources used in backlight systems are mainly of both edge-emitting and lambertian types. The scheme of the edge-emitting type LED mainly utilizes the property of medium total reflection to realize the control of light, but due to the limitation of total reflection angle, the scheme cannot accurately control the angular distribution of light intensity. Meanwhile, the center light intensity of the edge-emitting LED is low, so that dark spots are easily caused, and the uniformity of the backlight system is greatly influenced. The light intensity of the lambertian LED light source is distributed in a cosine mode, the central light intensity is large, and the central light intensity is gradually reduced from the center to two sides, so that the illumination formed on the target illumination surface is rapidly attenuated along with the increase of the emergence angle, and the requirement for uniform illumination is difficult to meet.
Disclosure of Invention
Aiming at the main problems in the ultra-thin design of a direct type backlight system and the Lambert type LED light distribution design, the invention provides a double-free-form surface optical lens for the ultra-thin direct type LED backlight system, which has the advantages of small volume, high light energy utilization rate, convenience in manufacturing and installation and capability of generating uniform illumination distribution. The invention adopts the following technical scheme:
the double-free-form surface optical lens for the ultrathin direct type LED backlight system is characterized by comprising two free-form surfaces which respectively form an incident surface and an emergent surface; the center of the bottom surface of the lens is provided with a cavity for the LED to be arranged in the cavity, and the cavity wall of the cavity is a free-form surface, namely an inner free-form surface, so as to form the incident surface; the outer side surface of the lens is also a free-form surface, namely an outer free-form surface, and forms the emergent surface;
the shape of the free-form surface lens is determined as follows:
a spatial rectangular coordinate system is established by taking an LED light source as an original point O, a plane where an LED bottom surface is located is an XOY plane, an axis which passes through the original point and is perpendicular to the plane is a z-axis, a light source solid angle is divided, an illumination area on a target illumination surface is divided into annular zones, then a mapping relation between the light source solid angle and the annular zone area on the target illumination surface is established by applying an energy conservation law, and then a final double-free-form-surface lens is obtained by applying a catadioptric law through a geometric relation.
Further, the two free-form surfaces are determined as follows:
firstly, the distance between the target illumination surface and the LED is h, the target illumination area is a circular area with the radius of r, and the total luminous flux of the LED light source is phisourceCentral light intensity of I0＝Φsourceπ, average illumination of the target illumination area is EaverageIn a coordinate systemIs the included angle between the emergent ray and the positive direction of the Z axis; discretizing the solid angle of the light sourceIs equally divided into M parts, thus obtainingAnd 0 is<i≤M；
For the free-form surface forming the incident surface, the main function is to control the emergent angle of the light, and the numerical range of the controlled emergent angle is set to be 0, thetamax]And is andand dividing the exit angle into M parts, each part being denoted as theta (i), to make it have a solid angle with the light sourceThe arrays are in one-to-one correspondence;
in each portionAngle of the object of study and luminous flux of：
Wherein,in generalRepresents the maximum half angle of scattering of light from the LED;
discretizing a circular illumination area corresponding to a source solid angleR is also divided equally into M parts, denoted as r (i); solid angle between circular illumination area r (i) and light source on target illumination surfaceEstablishing a one-to-one correspondence relationship between the arrays;
the relation between the average illumination intensity of the target illumination area and the total luminous flux of the LED light source is
Can be obtained by the above formulaaverageA value of (d);
establishing a corresponding relation between a solid angle of a light source and a ring belt region through energy conservation to obtain the following formula:
s (i) is the area of the ring belt region on the target surface, and S (i) ═ pi i [ r (i)2-r(i-1)2]By the above formula, the relative can be calculatedRadius r (i) of each ring belt region;
the included angle between the emergent ray of the LED and the z axis isAnd intersects with the inner free-form surface at Bi(x1(i),z1(i) Point intersecting with the outer free-form surface at C after refraction by the inner free-form surfacei(x2(i),z2(i) Point, through the outer free-form surface, intersects the target illumination surface at Di(r (i), H) points, BiUnit normal vector at pointCiUnit normal vector at point
The normal vector of a point on the curved surface is obtained according to the law of catadioptric reflection, the tangent plane is obtained by utilizing the normal vector, the coordinate of the point on the curve is obtained by obtaining the intersection point of the tangent plane and the incident ray, and the formula of the law of catadioptric reflection is as follows:
wherein n is the refractive index of the lens, the value of which depends on the lens material,is the unit vector of the incident light ray,is a unit vector of the outgoing light,is a unit normal vector;
for inside free-form surfaces, the angle formed by the light sourceThe incident vector can be obtained, the emergent vector can be obtained from theta (i), and the coordinate values of the upper point and the lower point of the inner free-form surface can be obtained by combining the catadioptric law:
and is
For the outer free-form surface, coordinate values of a point above and below the outer free-form surface can be obtained by combining the formula with the catadioptric law:
and is
a, b, c and d are obtained by the catadioptric law, and specifically are as follows:
(1) respectively determining the starting points of the inner free-form surface and the outer free-form surface;
(2) for the inner free-form surface, theAnd theta can obtain an incident vector and an emergent vector, the normal vector of the starting point can be calculated through the catadioptric law so as to determine a tangent plane of the point, and the second incident ray is intersected with the tangent plane so as to determine a second point;
(3) for the outer free-form surface, calculating a tangent plane of a starting point by using a catadioptric theorem, taking a second ray emergent vector of the inner curved surface as an incident vector of a second ray of the outer curved surface, and obtaining a second point by intersecting a straight line where the tangent plane of the starting point and the incident vector of the second ray are located;
(4) in the same way, the coordinates of the next point can be obtained by intersecting the tangent plane of the previous point with the straight line where the incident vector of the next light ray is located, the coordinates of all points on the inner side free-form surface and the outer side free-form surface are obtained through iteration, so that the lens contour curve is determined, and then the lens contour curve is rotated around the central axis to form the whole free-form surface.
Further, an optimization coefficient a is set for each ring belt region r (i)iChanging this optimization factor changes the radius of the girdle area and thus the amount of energy projected onto each girdle area.
After increasing the optimization coefficient, the energy of each ring band region is expressed as:
Φ(i)＝ai×Eaverage×π×[r(i)2-r(i-1)2]
where a isiIs constant and 0<ai，0<i≤M；
From the conservation of energy one can obtain:
the following two formulas can be obtained:
according to the formula, a new radius sequence can be obtained through iteration, a lens contour curve is obtained again by using the new radius sequence, then the new lens contour curve is fitted into an entity, and a is repeatedly modifiediUntil the illuminance on the target surface reaches a uniform distribution.
Further, the size of the value of i determines the accuracy of the shape of the free-form surface, and the smaller the value is, the more accurate the shape of the free-form surface is.
After the technical scheme is adopted, the double-free-form-surface lens which is small in size and used for the ultrathin direct type backlight system can be obtained. After light rays emitted from the LED pass through the double-free-form-surface lens, circular light spots with uniform illumination distribution can be formed on a target illumination surface, and the output efficiency of the lens is high.
The invention has the advantages that: due to the adoption of the double-free-form-surface lens, the LED light source has high luminous efficiency, light rays emitted from the light source can be completely collected and utilized, the output efficiency of the lens is very high, and meanwhile, the light ray emitting direction of the LED light source and the illumination distribution on the target illumination can be well controlled. Through area optimization, uniform illumination distribution on the target surface can be finally obtained. In addition, the middle part of the bottom surface of the lens is provided with a cavity for installing the LED, so that the LED light source is easy to install. Because the lens is small in size, a large amount of space is reserved, and heat dissipation of the system is facilitated. The invention can be applied to primary light distribution of the LED and the optics of the LED integrated light source, and can further improve the performance of an optical system by reasonably selecting parameters to achieve better illumination effect. Because the lens, the chip of the LED light source and the volume of the lens are smaller, the whole thickness of the backlight illumination system can be reduced, and the purpose of ultra-thin design is achieved. The invention is very beneficial to the light distribution design of Lambert type LEDs and the ultra-thin design of a direct type backlight system.
Drawings
Fig. 1 is a schematic diagram of uniform solid angle division of an LED light source in an embodiment.
Fig. 2 is a schematic diagram of uniform division of the target illumination area in the embodiment.
Fig. 3 is a schematic diagram illustrating the propagation of light rays emitted from the LED light source in the lens according to the embodiment.
Fig. 4 is a schematic diagram of optimization of the target illumination area in the embodiment.
Fig. 5 is a side sectional view of a dual free-form lens in an embodiment.
Fig. 6 is a side three-dimensional perspective view of a dual-free-form lens of an embodiment.
Fig. 7 is a bottom three-dimensional perspective view of a dual-free-form surface lens according to an embodiment.
Fig. 8 is a right three-dimensional perspective view of a dual-free-form surface lens in an embodiment.
Fig. 9 is a top three-dimensional perspective view of a dual-free-form surface lens in an embodiment.
Detailed Description
The following detailed description of the embodiments of the present invention will be made with reference to the accompanying drawings and examples, but the embodiments of the present invention are not limited thereto.
A double free-form surface optical lens for an ultrathin direct type LED backlight system is made of a transparent material, the transparent material is optical glass or PMMA or PC, and the lens comprises two free-form surfaces which respectively form an incident surface and an emergent surface. The center of the bottom surface of the lens is provided with a cavity for installing the LED in the lens, and the cavity wall of the cavity is a free-form surface to form the incident surface; the outer side surface of the lens is also a free-form surface, and constitutes the emission surface.
1. Initial conditions were set and the LED light source solid angle was divided.
Firstly, the distance between the target illumination surface and the LED is 12mm, the target illumination area is a circular area with the radius of 30mm, the total luminous flux of the LED light source is 200lm, and the central light intensity is I0200/pi cd, the average illumination intensity of the target illumination area is Eaverage. In a coordinate systemIs the outgoing ray is square to the Z axisAngle of direction isDiscretizing the solid angle of the light sourceAre equally divided into 200 parts, thus obtainingAnd 0 is<i is less than or equal to 200, i represents the number of equal parts. As shown in fig. 1.
For the inner free-form surface, the main function is to control the emergent angle of the light, and the emergent angle can be set according to the requirement, wherein the value range of the controlled angle is set to be [0, theta ]max]And is andand divided uniformly into 200 parts, each part being designated as theta (i), making it have a solid angle with the light sourceThe arrays are in one-to-one correspondence.
In each portionThe angle is the subject of study, and its luminous flux is:
here, theAnd isRepresenting the maximum half angle of scattering of light from the LED.
2. And (4) performing zone division on the target illumination area by using an energy conservation law.
Discretizing a circular illumination area corresponding to a source solid angleR is also divided equally into 200 parts, denoted as r (i). So as to form a solid angle between the circular illumination area r (i) and the light source on the target illumination surfaceOne-to-one correspondence is established between the arrays as shown in fig. 2.
The relation between the average illumination intensity of the target illumination area and the total luminous flux of the LED light source can be expressed as
E can be calculated by the above formulaaverageThe value of (c).
By establishing the correspondence between the solid angle of the light source and the ring belt region through energy conservation, an equation 1 can be obtained, as follows:
s (i) is the area of the ring belt region on the target surface, and S (i) ═ pi i [ r (i)2-r(i-1)2]The radius r (i) of each corresponding girdle region can be calculated by equation 1.
3. Discrete coordinates of the dual-free-form lens are calculated.
As shown in FIG. 3, assume that the angle between the outgoing light from the LED and the z-axis isAnd intersects with the inner free-form surface at Bi(x1(i),z1(i) Point intersecting with the outer free-form surface at C after refraction by the inner free-form surfacei(x2(i),z2(i) Point, through the outer free-form surface, intersects the target illumination surface at Di(r (i), H) points, BiUnit normal vector at pointCiUnit normal vector at point
When the free-form surface is constructed, the normal vector of a point on the surface is obtained according to the catadioptric law, the tangent plane is obtained by utilizing the normal vector, and the coordinate of the point on the curve is obtained by obtaining the intersection point of the tangent plane and the incident ray. The catadioptric law equation is as follows:
wherein n is the refractive index of the lens, the value of which depends on the lens material,is the unit vector of the incident light ray,is a unit vector of the outgoing light,is a unit normal vector.
For inside free-form surfaces, the angle formed by the light sourceThe incident vector can be obtained, the emergent vector can be obtained according to theta (i), the coordinate values of the upper point and the lower point of the inner free-form surface can be obtained by combining the catadioptric law, and the coordinate values are recorded as a formula 2, and the formula is as follows:
and is
For the outer free-form surface, coordinate values of a point above and below the outer free-form surface can be obtained by combining the formula 2 and the catadioptric law:
and is
a, b, c, d can be calculated from the law of catadioptric reflection.
The specific calculation method comprises the following steps:
(1) the starting points of the inner and outer free-form surfaces are determined respectively and have the values of (0, 2.9), (0, 3.2) in mm.
(2) For the inner free-form surface, theAnd theta can obtain an incident vector and an emergent vector, the normal vector of the starting point can be calculated through the catadioptric law so as to determine the tangent plane of the point, and the second incident ray intersects the tangent plane so as to determine the second point.
(3) And for the outer free-form surface, calculating a tangent plane of the starting point by using a catadioptric theorem, taking a second ray emergent vector of the inner curved surface as an incident vector of a second ray of the outer curved surface, and obtaining a second point by intersecting a straight line where the tangent plane of the starting point and the incident vector of the second ray are located.
(4) In the same way, the coordinates of the next point can be obtained by intersecting the tangent plane of the previous point with the straight line where the incident vector of the next light ray is located, the coordinates of all points on the inner-layer free-form surface and the outer-layer free-form surface can be respectively obtained through computer iteration, so that the contour curve of the lens is determined, and then the contour curve of the lens is rotated around the central shaft to form the whole free-form surface.
Example (c): for the inner free-form surface, the angle range controlled by the inner free-form surface is set to be [0, theta ]max]And is anduniformly dividing the light source into 200 parts, each part being denoted as theta (i), and discretizing the solid angle of the light sourceAre divided into 200 portions, and each portion is marked asSo as to correspond one-to-one to the theta (i) arrays. The starting point on the boundary line of the inner free-form surface is set to be (0, 2.9), that is, the distance from the LED to the top of the inner free-form surface of the lens is 2.9 mm. For the starting point, the normal vector of the starting point can be obtained by the law of refraction and reflectionThe normal vector and the initial point coordinate can obtain that the tangent line is z + 2.9-0, which is 3 formula; at an angle ofThe equation of the straight line of (1) is:this is formula 4; the two straight lines obtained by the formulas 3 and 4 are intersected, and x (2) and z (2) are obtained through an equation system consisting of the formulas 3 and 4.
And so on: the linear equation corresponding to the k-th point isThe corresponding tangent plane equation is Nx[k-1](x-x(k-1))+Nz[k-1](z-z (k-1)) ═ 0. And (4) obtaining the coordinates of the kth point by intersecting two straight lines, and obtaining the coordinate array of all data points on the boundary line of the inner free-form surface when k is 200.
4. And optimizing the ring belt area.
The invention provides a simple and feasible optimization scheme. Setting an optimization coefficient a for each ring belt region r (i)iVarying this optimization factor changes the radius of the girdle area and thus the amount of energy projected onto each girdle area, as shown in FIG. 4.
With the addition of the optimization coefficients, the energy of each ring band region can be represented by equation 5, as follows:
Φ(i)＝ai×Eaverage×π×[r(i)2-r(i-1)2]
where a isiIs constant and 0<ai，0<i≤200。
From the conservation of energy, equation 6 can be obtained as follows:
from the two formulae 5, 6, formula 7 can be derived as follows:
according to equation 7, a new radius sequence can be obtained by iterative calculation, and the lens profile curve is recalculated using this new radius sequence. Then, fitting the new lens contour curve to an entity and simulating the entity, and repeatedly modifying a according to the actual simulation resultiUntil the illuminance on the target surface reaches a uniform distribution.
5. Fitting the resulting points to an entity using mechanical modeling software
And sequentially importing the obtained coordinates of the discrete points into mechanical modeling software for fitting, and then rotating the obtained curve around a central axis to obtain a final double-free-form-surface optical lens solid model.
Fig. 1 is a spherical coordinate diagram of an LED light source in an embodiment, and a solid angle of the LED light source is uniformly divided according to the spherical coordinate diagram. A uniformly divided ith solid angle 101 is shown.
Fig. 2 is a schematic diagram of division of the annular zone of the target illumination area in the embodiment, wherein the annular zone comprises an LED light source 202, and the target illumination area 203 is a divided annular zone 204.
Fig. 3 is a schematic diagram illustrating the propagation of light rays emitted from the LED light source in the lens according to the embodiment. Including the inner free-form surface 301 of the lens, the outer free-form surface 302 of the lens; the two cooperate to achieve uniform illumination at the target illumination area. The target illumination surface 303.
Fig. 4 is a schematic diagram of optimization of the target illumination area in the embodiment, which includes a target illumination area 401, an optimized girdle area 402, and an optimization coefficient 403.
Fig. 5 is a side sectional view of the double free-form surface lens obtained by the above-described arrangement, and the lens has two free-form surfaces, including an outer free-form surface 501 of the lens and an inner free-form surface 502 of the lens.
Fig. 6 is a side three-dimensional perspective view of the double-free-form-surface lens obtained by the above scheme, wherein the lens comprises an outer free-form surface 601 and an inner free-form surface 602; a bottom circular region 603 of the lens into which the LED can be mounted; and a bottom planar surface 604 of the lens.
Fig. 7 is a bottom three-dimensional perspective view of the double-free-form-surface lens obtained by the above solution, wherein the lens comprises an outer free-form surface 701 and an inner free-form surface 702; a bottom circular region 703 of the lens; and a bottom planar surface 704 of the lens.
Fig. 8 is a right three-dimensional perspective view of a double-free-form-surface lens obtained by the above-described scheme, in which an outer free-form surface 801 and an inner free-form surface 802 of the lens are broken; and a bottom plane 803 of the lens.
Fig. 9 is a top three-dimensional perspective view of the double-free-form-surface lens obtained by the above-described method, including an outer free-form surface 901 and an inner free-form surface 902 of the lens.
By adopting the technical scheme, the double-free-form-surface lens which is small in size and used for the ultrathin direct type backlight system can be obtained. After light emitted from the LED passes through the double-free-form-surface lens, a circular light spot with uniform illumination distribution can be formed on a target illumination surface, and the output efficiency of the lens is high. Due to the adoption of the double-free-form-surface lens, the LED light source has high luminous efficiency, light rays emitted from the light source can be completely collected and utilized, the output efficiency of the lens is very high, and meanwhile, the light ray emitting direction of the LED light source and the illumination distribution on the target illumination can be well controlled. Through area optimization, uniform illumination distribution on the target surface can be finally obtained. In addition, the middle part of the bottom surface of the lens is provided with a cavity for installing the LED, so that the LED light source is easy to install. Due to the small size of the lens, a large amount of space is reserved, which is beneficial to the heat dissipation design of the system.
Claims (1)
1. The double-free-form surface optical lens for the ultrathin direct type LED backlight system is characterized by comprising two free-form surfaces which respectively form an incident surface and an emergent surface; the center of the bottom surface of the lens is provided with a cavity for the LED to be arranged in the cavity, and the cavity wall of the cavity is a free-form surface, namely an inner free-form surface, so as to form the incident surface; the outer side surface of the lens is also a free-form surface, namely an outer free-form surface, and forms the emergent surface;
the shape of the free-form surface lens is determined as follows:
setting initial conditions and dividing solid angles of the LED light source;
firstly, the distance between the target illumination surface and the LED is 12mm, the target illumination area is a circular area with the radius of 30mm, the total luminous flux of the LED light source is 200lm, and the central light intensity is I0200/pi cd, the average illumination intensity of the target illumination area is Eaverage(ii) a In a coordinate systemIs the angle between the emergent ray and the positive direction of the Z axisDiscretizing the solid angle of the light sourceAre equally divided into 200 parts, thus obtainingAnd 0 is<i is less than or equal to 200, i represents the number of equal parts;
for the inner free-form surface, the main function is to control the emergent angle of the light, and the emergent angle can be set according to the requirement, wherein the value range of the controlled angle is set to be [0, theta ]max]And is andand divided uniformly into 200 parts, each part being designated as theta (i), making it have a solid angle with the light sourceThe arrays are in one-to-one correspondence;
in each portionThe angle is the subject of study, and its luminous flux is:
here, theAnd isRepresents the maximum half angle of scattering of light from the LED;
dividing the target illumination area into zones by using an energy conservation law;
discretizing a circular illumination area corresponding to a source solid angleEqually dividing r into 200 parts, which is denoted as r (i); so as to form a solid angle between the circular illumination area r (i) and the light source on the target illumination surfaceEstablishing a one-to-one correspondence relationship between the arrays;
the relation between the average illumination intensity of the target illumination area and the total luminous flux of the LED light source can be expressed as
E can be calculated by the above formulaaverageA value of (d);
the corresponding relation between the solid angle of the light source and the ring belt area is established through energy conservation:
s (i) is the area of the ring belt region on the target surface, and S (i) ═ pi · [ r (i)2-r(i-1)2]The radius r (i) of each corresponding girdle region can be calculated;
calculating discrete coordinates of the double-free-form-surface lens:
suppose that the angle between the outgoing light from the LED and the z-axis isAnd intersects with the inner free-form surface at Bi(x1(i),z1(i) Point intersecting with the outer free-form surface at C after refraction by the inner free-form surfacei(x2(i),z2(i) Point, through the outer free-form surface, intersects the target illumination surface at Di(r (i), H) points, BiUnit normal vector at pointCiUnit normal vector at point
When the free-form surface is constructed, the normal vector of a point on the surface is obtained according to the catadioptric law, a tangent plane is obtained by utilizing the normal vector, the coordinate of the point on the curve is obtained by obtaining the intersection point of the tangent plane and the incident ray, and the catadioptric law formula is as follows:
wherein n is the refractive index of the lens, the value of which depends on the lens material,is the unit vector of the incident light ray,is a unit vector of the outgoing light,is a unit normal vector;
for inside free-form surfaces, the angle formed by the light sourceCan obtainThe outgoing vector can be obtained from θ (i) on the incident vector, and the coordinate values of the upper and lower points of the inner free-form surface can be obtained by combining the catadioptric law as follows:
and is
For the outer free-form surface, the coordinate values of the upper point and the lower point of the outer free-form surface can be obtained by combining the formula with the catadioptric law:
and is
a, b, c and d can be calculated by the catadioptric law;
the specific calculation method comprises the following steps:
(1) respectively determining the starting points of the inner and outer free-form surfaces, wherein the values are (0, 2.9), (0, 3.2) and the unit mm;
(2) for the inner free-form surface, theAnd theta can obtain an incident vector and an emergent vector, the normal vector of the starting point can be calculated through the catadioptric law so as to determine the tangent plane of the point, and the second incident ray is intersected with the tangent plane so as to determine a second point;
(3) for the outer free-form surface, calculating a tangent plane of a starting point by using a catadioptric theorem, taking a second ray emergent vector of the inner curved surface as an incident vector of a second ray of the outer curved surface, and obtaining a second point by intersecting a straight line where the tangent plane of the starting point and the incident vector of the second ray are located;
(4) in a similar way, the coordinates of the next point can be obtained by intersecting the tangent plane of the previous point with the straight line where the incident vector of the next light ray is located, the coordinates of all points on the inner-layer free-form surface and the outer-layer free-form surface can be respectively obtained through computer iteration, so that the contour curve of the lens is determined, and then the contour curve of the lens is rotated around the central shaft to form the whole free-form surface;
optimizing a girdle area:
setting an optimization coefficient a for each ring belt region r (i)iChanging the optimization coefficient can change the radius of the girdle area, thereby changing the energy projected to each girdle area;
with the addition of the optimization coefficients, the energy of each ring band region can be represented by equation 5, as follows:
Φ(i)＝ai×Eaverage×π×[r(i)2-r(i-1)2]
where a isiIs constant and 0<ai，0<i≤200；
From the conservation of energy one can obtain:
further obtaining:
a new radius sequence can be obtained through iterative calculation, and the lens contour curve is recalculated by using the new radius sequence; then, fitting the new lens contour curve to an entity and simulating the entity, and repeatedly modifying a according to the actual simulation resultiUntil the illuminance on the target surface reaches a uniform distribution;
fitting the obtained points into an entity by using mechanical modeling software; and sequentially importing the obtained coordinates of the discrete points into mechanical modeling software for fitting, and then rotating the obtained curve around a central axis to obtain a final double-free-form-surface optical lens entity.
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| CN106287572A (en) * | 2015-06-26 | 2017-01-04 | 核工业西南物理研究院 | Annular LED light fixture optical mask and light fixture thereof |
| CN105351886B (en) * | 2015-12-09 | 2023-12-22 | 欧普照明股份有限公司 | Diffusion lens and lighting device with same |
| CN107191861B (en) | 2017-07-21 | 2020-01-17 | 中山市华南理工大学现代产业技术研究院 | Double-free-form-surface lens with uniform color temperature |
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| CN107654962A (en) * | 2017-09-18 | 2018-02-02 | 佛山科学技术学院 | A kind of LED reflector design methods of high uniform illumination |
| CN108613136A (en) * | 2018-04-09 | 2018-10-02 | 深圳民爆光电技术有限公司 | A kind of control method and system generating free-form surface lens based on energy distribution method |
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| CN111797445A (en) * | 2020-07-14 | 2020-10-20 | 深圳市千百辉照明工程有限公司 | Design method of LED flower-shaped lighting lens and lens |
| CN115327681A (en) * | 2022-08-16 | 2022-11-11 | 广州奕至家居科技有限公司 | Method and system for generating optical lens surface shape |
| CN118169920A (en) * | 2024-04-01 | 2024-06-11 | 东莞市顺为光电有限公司 | Backlight module with light weight design |
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